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International Conference on Advances in Radiation Oncology #ICARO3

Europe/Vienna
Description

ICARO-3-Banner

The International Atomic Energy Agency (IAEA) is organizing the third International Conference on Advances in Radiation Oncology (ICARO3), following the success of the previous conferences (ICARO and ICARO2) in 2009 and 2017. The advances in radiotherapy in the last years have been striking, although numerous challenges are still to be faced, including achieving access to high standard cancer care in many countries. New radiotherapy techniques have been implemented in the past decade, including three-dimensional conformal therapy, stereotactic radiotherapy, intensity modulated radiation therapy, image guided radiation therapy, tomotherapy, new brachytherapy and unsealed-source techniques, and proton and heavy ion therapy. The increased use of these complex techniques, coupled with the need to treat more patients in less time, will continue to drive a reliance on high-end technologies and impose a financial burden on health care programmes. In addition, the development and implementation of a quality assurance programme for these new techniques is a major challenge in Member States.

The conference, which will be held online as a virtual event from 16-19 February 2021, will give health care professionals an opportunity to review the current developments in clinical applications in the fields of radiation oncology, radiation biology and medical physics, with a view to addressing the challenge of cancer management in Member States.

It will also critically examine the pivotal role of emerging radiotherapy techniques in tackling the health challenges common to many Member States.

The virtual educational event will consist of keynote lectures which will be available both as a broadcast and on-demand, thematic refresher courses and workshops, and e-poster showcases.

An appropriate number of accredited continuing medical education (CME) credits will be awarded to participants.

ICARO3 Focal Point
    • 08:00 08:30
      Opening Addresses
      • 08:00
        ICARO-3 Official Opening 5m
        Speaker: Rafael Mariano Grossi (Director General International Atomic Energy Agency (IAEA))
      • 08:05
        Welcome remarks 8m
        Speaker: Najat Mokhtar (Deputy Director General, Department of Nuclear Sciences and Applications, IAEA)
      • 08:13
        Welcome remarks 8m
        Speaker: May Abdel Wahab (International Atomic Energy Agency, Director Division of Human Health)
    • 08:30 09:00
      From ICARO 2 to ICARO 3: Opening Keynotes

      Learning Objective(s):
      Describe developments and challenges in radiation oncology and medical physics in the last 5 years since ICARO 2
      Discuss hypofractionation as an example of COVID-19 impact on radiotherapy practice

      • 08:30
        From ICARO 2 to ICARO 3: Radiation Oncology 15m
        Speaker: Eduardo Rosenblatt
      • 08:45
        From ICARO 2 to ICARO 3: Physics 15m
        Speaker: Geoffrey Ibbott (UT MD Anderson Cancer Center)
    • 09:00 10:00
      Panel Discussion: Global Initiatives

      Learning objective(s):
      Discuss challenges in the access and implementation of radiation oncology globally
      Identify innovations and solutions to address challenges

      • 09:00
        Global Initiatives 1h

        The panel will discuss the challenges in the access and implementation of radiation oncology globally and identify innovations and solutions to address challenges.

        Speaker: May Abdel Wahab (International Atomic Energy Agency, Director Division of Human Health)
        • Hub and Spoke Model 10m
          Speaker: Rajendra Achyut Badwe (TATA Memorial Centre)
        • Oncology Commissions and Impact in Global Cancer 10m
          Speaker: David Collingridge (Lancet Oncology )
        • Current Global Initiatives 10m
          Speaker: Minghui Or Nono Ren (World Health Organization (WHO))
        • Non traditional solutions for Setting up an Oncology Dept 10m
          Speaker: Sherif Abouelnaga (Pediatric Oncology Hospital )
        • Global Network Approach 10m
          Speaker: Tomislav Mijalshevic (Cleveland Clinic)
        • Experience and Challenges 10m
          Speaker: Hugo Marsiglia (Médico del Instituto Oncológico Fundación Arturo López Pérez (FALP))
    • 10:00 10:30
      Addressing technological gap: Addressing Technological Gap

      Learning objective(s):
      Discuss requirements to ensure safe and effective transition to new technologies

      • 10:00
        Technological Gap: Clinical Perspective 15m
        Speaker: Michael Barton (University of New South Wales, Australia)
      • 10:15
        Technological Gap: Physics Perspective 15m
        Speaker: Jacob Van Dyk (Departments of Oncology and Medical Biophysics, Western University, London, Ontario, Canada)
    • 10:30 11:00
      Artificial intelligence: Advanced Technologies

      Learning objective(s):
      Discuss recent advances in artificial intelligence / machine learning and their applications in radiation oncology
      Discuss challenges and considerations in the implementation

      • 10:30
        Advanced Technologies - IT/AI 30m

        The keynote lecture will discuss the recent advances in artificial intelligence / machine learning and their applications in radiation oncology. It will also discuss the challenges and considerations in implementation.

        Speaker: Ben Heijmen (ESTRO)
    • 11:00 11:30
      Paper Session 1:Clinical Research: Proffered Papers & e-Posters

      Session for the presentation of Oral presentations on Clinical Research

      • 11:00
        Is Watch and wait approach feasible for patients with complete response post neoadjuvant therapy in Low Middle Income Countries? 7m

        Background - Neoadjuvant chemoradiation (NACTRT) followed by surgery and adjuvant systemic therapy remains the management option for locally advanced (T3-T4N+) rectal tumours.
        APR remains the surgery of choice for distal rectal tumours which leads to permanent colostomy , loss of urinary and sexual functions and altered quality of life. This colostomy also leads to stigmatization of patients who are relatively young (median age 47 years) especially in the Low Middle Income Countries leading to a dropout rate or refusal for APR in more than 20% of the patients [1-2].
        For patients achieving good and complete clinicoradiological response the Watch and Wait strategy was proposed by Habr-Gama and hence been implemented and reported in many studies [3-4]. However, this strategy involves strict follow up schedule and doing surgery at the time of regrowth. Can this strategy be implemented in LMIC’s where the understanding of this approach and adherence to follow up schedule may be difficult. Also is it more economical compared to the patients undergoing surgery. In this study we retrospectively analyzed the outcomes of patients managed by wait and watch approach in terms of organ preservation rate, recurrence rate and survival. We also looked at the compliance and cost benefit compared to the patients undergoing surgery at our institution.
        Methods and materials- Patients with rectal tumours, clinically T2-T4 N+ tumours, were included in the study. All the patients were staged with MRI pre and post 6 -8 weeks of NACRT.
        All patients received NACTRT – EBRT to a dose of 45-50Gy in 1.8-2Gy/# with concurrent capecitabine.
        All patients were assessed at end of radiation for response.
        Twenty-two (40%) patients with near complete or complete clinical response (cCR) on DRE, escalated dose of radiation were given in form of endorectal brachytherapy mostly 8Gy/2# or EBRT 5.4Gy/3# (if DRE was painful).
        Further response evaluation was done at 6th week and 12th week post treatment completion.
        Patients with near complete or cCR response at 12th week were given option of immediate surgery vs wait and watch, and patients refusing surgery, after obtaining consent, were observed with 3 monthly with DRE, MRI pelvis and sigmoidoscopy.
        Here we present the results of the patients attaining near complete or cCR at 12th week and kept on wait and watch.
        Results- 55 patients were followed up from December 2013 to December 2019, among which 39 had cCR (71%) while 16 had nCR(29%) post NACTRT.
        Majority (80%) were distal rectal tumours (0-5 cm from anal verge) and 74.5% were T3 tumours. Tweny-two (40%) of the patients received brachytherapy boost.
        61.5% of patients had achieved cCR at 12th week post NACTRT and rest continued to have nCR.
        At a median follow-up of 33 months, overall 11(20%) patients have local regrowth; six patients with nCR and 5 with cCR.
        Out of the 11 patients who had local regrowth, seven underwent surgery (4 APR, 2 ISR and 1 LAR), 4 refused surgery and is still alive with disease. Overall compliance rate to the protocol was 92.7%.
        The overall organ preservation rate was 87%.
        Six (11%) patients developed distant metastasis (3 along with local regrowth and 3 without). Three patients had metastasis in liver , 2 lung and 1 leptomeningeal.
        Five of 6 patients with DM underwent metastatectomy and are disease free till follow up, whereas only one patient in the entire cohort died of leptomeningeal metastasis.
        The 3 year colostomy free survival, non regrowth recurrence free survival, and OAS was 92.7%,94.5% and 98%.
        On performing cost benefit analysis patients on W&W approach mean cost per patient in the W&W group was 1.4 Lacs INR (1854 USD) where as it was 4.5 Lacs (5960 USD) in patients undergoing routine NACRT followed by surgery.
        Conclusions- This study has shown wait and watch approach is a possible alternative management option for patients attaining cCR after NACTRT with local regrowth risk being 20% but majority of which is surgically salvageable. This leads to excellent survival with added benefit of organ preservation in majority.
        It is acceptable and feasible with a good compliance and economically 3 times cost effective compared to patients undergoing surgery. This is very relevant for patients in Low Middle Income Countries where expertise is available.
        References
        1. Patil PS, Saklani A, Gambhire P, et al. Colorectal Cancer in India: An Audit from a Tertiary Center in a Low Prevalence Area. Indian J Surg Oncol. 2017;8(4):484-490.
        2. Shinde RS, Katdare N, Kumar NAN, Bhamre R, Desouza A, Ostwal V, Engineer R, Saklani A. Acta Oncol. 2018 Dec;57(12):1721-1723 Impact of histological subtype on treatment outcomes in locally advanced rectal adenocarcinoma treated with neoadjuvant chemoradiation

        Speaker: Reena Engineer (Tata Memorial Centre, Mumbai, India)
      • 11:07
        Modern possibilities of nuclear medicine in the treatment of patients with recurrence prostate cancer after radical prostatectomy 7m

        Purpose or Objective
        The aim of our study is to analyze the long-term results of salvage radiation therapy (SRT) for patients with recurrence of prostate cancer (PCa) after radical prostatectomy (RP) using modern diagnostic capabilities of nuclear medicine.
        Material and Methods
        Biochemical recurrence after radical prostatectomy – subsequent detectable PSA level after radical prostatectomy that increases on 2 or more subsequent laboratory determination. Clinical recurrence – is a type of biochemical recurrence in which a substrate of a locoregional recurrence tumor is detected by modern high-tech diagnostic capabilities, including multiparametric MRI (mp-MRI) and positron emission tomography/computed tomography (PET/CT) with 68Ga-PSMA. Using this diagnostic approach, among all this group of patients, locoregional recurrence tumor was visualized in 261 (63.5%) patients: 53% - in prostate bed, 10.5% - in regional pelvic lymph nodes.
        In 2009 we developed and implemented in clinical practice variant of SRT in classical fractionation, which consists in irradiating the regional pelvic lymph nodes to 44 Gy, the fossa of prostate gland to 66 Gy and the area of recurrence to 72 Gy. In 2013 we created and patented the technique of hypofractionation SRT. Radiotherapy have been prescribed to the pelvic lymphatic nodes to 46.8 Gy of 1.8 Gy per fraction, to the prostate bed - 61.1 Gy of 2.35 Gy per fraction and clinical recurrence - 65 Gy of 2.5 Gy each, in 26 fractions using simultaneous integrated boost. Some patients receive сombination SRT and hormonal therapy (HT) (6-8 months (agonists LHRH).
        Results
        411 patients were treated from March 2009 to December 2018. Median of follow up – 48 (18-131) months. 42 (10.2%) of 411 patients were treated by classic fractionation SRT, 369 (89.8%) - by hypofractionation SRT. Survival rates were 3-year and 5-year disease free survival (DFS) - 81.3% and 77.6%, respectively. Locoregional control - 100%. The results of our study indicate two main negative factors in the prognosis of the efficacy of SRT – the period of prostate specific antigen (PSA) doubling time less than 6 months (p = 0.035) after RP and a higher PSA level, especially more than 0.5 ng/ml before SRT (p = 0.037). In our study, 247 (60.1%) of 411 patients were treated by combination SRT and HT. It was found that 5-year DFS among patients who received a combination of SRT and HT, is higher rates - 81%, compared with patients who were treated by monotherapy SRT - 73.5% (p = 0.5). However, retrospectively analyzing, we noted that patients who were treated by combination SRT and HT had more unfavorable prognosis factors: pT3a-b, pN1, Pn1, PSA level > 1 ng/ml at time the beginning of treatment, the period of PSA doubling time less than 6 months, the presence of regional relapses after RP, the size of the recurrent tumor more than 10 mm. We also have found that pN1 is a reliable adverse prognosis factor effectiveness of SRT. So, a 5-year DFS is significantly (p=0.012) lower in patients with pN1 than with pN0, it is 52% and 83%, respectively.
        Conclusion
        Excellent survival rates and locoregional controls of disease is the result of combination nuclear medicine advanced diagnostic approaches and high-precision radiation therapy in the treatment of patients with prostate cancer recurrence after radical prostatectomy

        Speaker: Petr Bulychkin
      • 11:14
        Survival benefits of adding palliative whole brain radiotherapy in non-small cell lung cancer with brain metastases unsuitable for resection or radiosurgery: A clinical prediction rule 7m

        INTRODUCTION: The QUARTZ trial demonstrated heterogeneous survival benefits of whole brain radiotherapy (WBRT) in non-small cell lung cancer (NSCLC) patients with brain metastases inappropriate for surgery or stereotactic radiosurgery/radiotherapy (SRS/SRT) which showed a favourable survival outcome with WBRT for those who were younger than 60 years old and potential benefits in patients with good Karnofsky Performance Status (KPS); ≥70%, no extra-cranial metastases and controlled primary NSCLC. The National Institute for Health and Care Excellence (NICE) guideline (NG99) recommends omission of WBRT for NSCLC patients with brain metastases who are not suitable for surgery or SRS/SRT with KPS<70%, while the National Comprehensive Cancer Network guideline (NCCN Version 2.2020) states that it is reasonable to hold on WBRT in selected NSCLC patients with extensive brain metastases if available CNS active agents exist. A question regarding proper selection of these patients to receive WBRT is to be solved. The objective of this study is to evaluate the added survival benefits of WBRT by developing and internal validating the individual survival prediction model for NSCLC patients with brain metastases inappropriate for surgery or SRS/SRT by using WBRT as a main prognostic factor.

        METHODS: We retrospectively collected 479 NSCLC patients with brain metastases treated with either WBRT or optimal supportive care (OSC) from January 2004 to December 2019 from Siriraj hospital database using clinical characteristics as potential predictors, previously established elsewhere. The primary outcome was overall survival. By the time of analysis, 452 patients found dead. According to the rule of thumb of 10 events per predictor, 45 predictors were adequately examined in our model. The Cox proportional hazard regression was used for survival analyses. Linearity of continuous variable was checked using Martingale residuals. The Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) statement was followed. To handle with missing predictors, multiple imputation by chain equations (MICE) with thirty imputations performing on the complete data set of all participants using identical known information generated primary analysis model. A backward elimination method was used to decide which of the potential predictors should be included in our reduced model based on Akaike information criterion (AIC), keeping predictors with a p-value of less than 0.157. The bootstrap procedure, a random resampling with replacement was performed for optimism-correction model. We combined the estimates across imputed data sets using Rubin’s rules to produce final parameter estimates for the final model including baseline survival and slope. The model performance included Harrell’s C-index and calibration plot. Finally, the nomogram and web-based individual calculator were generated. All the above analyses were carried out using Stata version 14 and R.

        RESULTS: Of 479 patients, 389 (81.2%) received WBRT. There was less female gender in WBRT group, they had better KPS; ≥70% (65.5% vs 38.5%), presented with milder symptoms (39.8% vs 25.3%), had greater number of measurable lesions (87.4% vs 63.8%), were more likely to receive further systemic treatment (35.7% vs 15.2%) and had better prognosis by Graded Prognostic Assessment for Lung Cancer Using Molecular Markers (Lung-molGPA). Genetic mutation was not tested in three-quarters of the whole cohort. Better survival in WBRT group was observed (5.1 vs 2.3 months). Median follow up time was 4.3 (1.0-8.4) months. Potential predictors included age, gender, KPS, histology, EGFR/ALK status, neurological symptom, extracranial disease, previously received systemic treatment, presence of measurable lesions, received further systemic treatment and WBRT. Extra-cranial disease status and presence of measurable lesions were critical missing values. After MICE and dropping the candidate predictors step wise based on AIC, the following predictors were included in the reduced survival model: gender, KPS, neurological symptom, extra-cranial disease, previously received systemic treatment, received further systemic treatment and WBRT. WBRT exhibits a negative score, a good predictor. The final optimism-correction model was generated using shrinkage factor generated by bootstrapping with a C-index of 70.9% (69.1-73.8%) and an acceptable calibration. A model-transformed nomogram and web-based calculator were generated and available online at https://siriraj.cloud:9001/survival/. To put it simply, there were two characteristics demonstrated greatest benefit of WBRT: (1) patients who had controlled primary NSCLC and no extra-cranial metastases and (2) those who received further systemic treatment.
        We also did a separate analysis for 117 patients with known genetic mutation status. The final model included only three predictors: extra-cranial disease, received further systemic treatment and WBRT. The genetic status variable was dropped out of the model in the same fashion as we did for the whole cohort. There was only ten percent of the patients received further targeted drug which could obscure the strength of genetic mutation variable. We are planning on updating our model in the modern era database and external validating thereafter.

        CONCLUSION: This nomogram is able to help clinicians to make decision making for whole brain radiotherapy in the tough situation. Further external validation is encouraged to be performed.

        Speaker: Kyrhatii Trikhirhisthit (Sawanpracharak hospital, Collaborative Project to Increase Production of Rural Doctor (CPIRD) Medical Education Center affiliated to Mahidol University, Nakhonsawan, Thailand)
      • 11:21
        EVOLUTION AND PROGNOSIS OF JUVENILE NASOPHARYNGEAL CARCINOMA: results from of a study on 68 children in Salah Azaiz Institute in Tunisia 7m

        Abstract

        Introduction: Juvenile nasopharyngeal carcinoma (NPC) is relatively common in Tunisia. The classification and treatment of NPC have been impacted by the increased rate of early diagnosis and advances in imaging techniques over time. The objective of our work was to study the epidemiological, clinical, therapeutic and evolutive aspects of juvenile NPC during the period between January 2004 and December 2014.

        Methods: Our study was retrospective done on 68 patients younger than 18 years old with a CNP treated at Salah Azaiez Institute between January 2004 and December 2014. Patients with histological cavum cancer other than undifferentiated carcinoma (UCNT type) or poorly differentiated carcinoma were excluded. All our patients had a clinical and paraclinical assessment allowing staging of the tumor according to the TNM 2010 classification. The study of survival and prognostic factors was done after a descriptive analysis. These prognostic factors were studied in uni and multivariate analysis. The chosen significance level was 0,05.

        Results: The median age of our patients was 14,7 years with a sex ratio of 2. The average consultation delay was 4 months. Rhinological signs were the most frequent reason for consultation. According to 2010 TNM classification, T3-T4 tumors accounted for 78% of all cases and nodal involvement was classified as N2-N3 in 63% of patients. Non-metastatic patients had radiotherapy (on the cavum and lymph nodes areas) associated (differently) with chemotherapy in 97% of cases. For metastatic patients, the treatment consisted of radiotherapy contracted on bone metastasis and first chemotherapy and radiotherapy (+/- concomitant chemotherapy) on the primitive and lymph nodes areas. After an average follow-up of 94 months, 78% of our patients were alive and in complete remission, 19% were in therapeutic failure with 16% of metachronous metastases. The overall survival at 5 years in the absence of therapeutic failure was 95% and that in the presence of therapeutic failure was 30%. Late toxicity was dominated by hyposialia and dystrophic complications.

        Conclusion: Treatment of NPC is based on the combination of chemotherapy and radiotherapy. However, metastatic relapses are a common mode of failure. High radiotherapy doses are associated with excellent local control rates with increased late sequelae. Innovative radiotherapy techniques, including conformal radiotherapy with or without intensity modulation, are promising and could overcome toxicity problems while maintaining an excellent local control rate.
        Key-words : Nasopharyngeal carcinoma, Child, Prognosis, Survival

        Speaker: Semia Zaraa (Salah azaiz institute, Department of Radiotherapy)
    • 11:30 12:00
      Paper Session 2: Implementation of New Technologies

      Session for the presentation of Oral presentations on Implementation of New Technologies

      • 11:30
        Optimization parameters in bladder and rectum for gynecologic cancer treatment with VMAT Technique through ProKnow platform 7m

        Optimization parameters in bladder and rectum for gynecologic cancer treatment with VMAT Technique through ProKnow platform.

        M. Bertero, R. Gonzalez Armesto, J. De Brida, M. S. Gallo, R. Ruggeri.
        Centro Oncológico Integral, Leben Salud.

        Introduction
        Gynecologic cancer represents 14% of new cancer cases in women in Argentina (Ministerio de Salud, 2018). The main treatment options to this disease are external radiotherapy, brachytherapy and chemotherapy. In the first two, the predominant concern are the dose levels administered to organs at risk (OARs), where bladder and rectum are considered critical organs due to their proximity to the treatment region.
        Although the tolerance doses defined for these organs (in QUANTEC) are higher than the prescription dose recommended for pelvic irradiation, it represents good practice to optimize dose to healthy tissues to the minimum values achievable, according to ALARA principle. Volumetric Arc Therapy (VMAT) technique allows optimization of the dose delivered to these organs without compromising the dose to the target volume (PTV). That is the reason why sometimes this technique is chosen over Tridimensional Conformal Therapy (3D-CRT) technique, where dose optimization is limited.
        In this work, Dose Volume Histograms (DVH) from gynecologic treatment plans using VMAT techniques are analyzed with Elekta’s ProKnow platform, to collect statistical data from our population and identify average dose distributions in OARs, with the objective of establishing dose optimization parameters.

        Methodology
        Whole pelvic radiotherapy plans for gynecological malignancies, with a prescription dose of 46 Gy, in fractions of 2 Gy per day, planned in Elekta’s TPS Monaco with VMAT technique and treated between June 2018 and June 2020 at Centro Oncologico Integral and Fundación Médica de Río Negro y Neuquén were identified. The selected plans were anonymized and uploaded to Elekta’s platform Proknow, grouping these patients in a data collection destined to investigation. A scorecard was created in order to evaluate the dose delivered to organs at risk, as well as the PTV dose coverage.
        In the development of the scorecard, evaluation metrics were defined: V10, V15, V20, V25, V30, V35, V40, V45, medium dose and maximum dose both in bladder and rectum and, homogeneity and conformality index, as well as D95 to evaluate the PTV. Lastly, the number of monitor units (MU) were included in the analysis as an indicator of the treatment plan’s level of complexity. For statistical analysis, the median of each evaluated metric was selected. These values were used to define optimization parameters.
        Next, the plans were replanned using the optimization values established. These plans were then uploaded to ProKnow platform and subjected once again to evaluation by scorecards to assess the results of optimization.

        Results
        A comparison of the DVH of the original and optimized plans shows a reduction in the evaluated metrics. With regards to the rectum, the median of low dose values (V10-V20) decreased by up to 18%. At medium dose levels (V20-V35), the reduction in the median had greater impact, achieving a decrease of up to 23%; for the high dose range, (V35-V45), a decrease in the median of up to 11% was achieved. The median dose distribution in the rectum was reduced by 10%, from 30 Gy to 27 Gy.
        In the bladder, the median of the low dose values (V10-V20) decreased by 19%; for medium doses (V20-V35), the median decreased by 21% and for high doses (V35-V45), the decrease in doses had a considerable result, reaching a decrease of 36% for V40 and 47% for V45. The median dose was reduced by 12%.
        As for PTV and the complexity of the plan, no significant variations were observed.

        Conclusion
        Considering that the dose constraints for OARs involved in the irradiation of gynecological malignancies are higher than the dose levels administered in whole pelvic irradiation, all the plans analysed in the first instance comply with the reference values adopted.
        With the implementation of ProKnow platform it was possible to quickly and effectively identify the dose distributions of our population, and determine optimization parameters for these treatment plans.
        As expected, the dose distributions of our population were homogenized, showing less variability in values since all treatment plans were executed under the same optimization criteria. In most cases, a decrease in the dose values delivered to the risk organs was found without a considerable compromise to PTV coverage and plan complexity.
        ProKnow proved to be a useful tool for statistical analysis of the population that allows continuous improvement in treatment planning and optimization of workflow, streamlining the evaluation and comparison of plans for clinical decision-making.

        Speaker: Micaela Agustina Bertero (Leben Salud)
      • 11:37
        Evaluation of artificial intelligence based contouring tools in prostate cancer radiation therapy planning 7m

        Introduction of the study
        Organs at risk (OAR) and target volume contouring is a labour intensive part of the radiation therapy (RT) treatment planning process. Recently, multiple vendors have introduced a segmentation tools based on artificial intelligence (AI) to reduce planning time through automation. In this study, the accuracy and efficiency gain for prostate cancer patient contouring was assessed for three vendors: Mirada Medical, Mvision AI OY and TheraPanacea ART-Plan.annotate.

        Methodology
        CT scans of 5 prostate cancer patients that had not undergone prostatectomy and did not have hip replacements were selected for this study. Following structures were manually segmented on all of the CT scans by experienced radiation therapy technologists (RTT): body, bladder, rectum, prostate, seminal vesicles, femoral heads and penile bulb. Contouring time for each patient was measured. In order to estimate the time realistically, the contouring conditions were in line with the Centre's usual practice. Contours were created using Elekta MonacoSIM (5.11) TPS and its semi-automatic tools until the clinically acceptable results were achieved.
        The same 5 CT scans, excluding the structure sets, were anonymized and sent to three different vendors to be segmented automatically. Segmentation accuracy was evaluated by comparing the automatically segmented structures to the ones created manually. Standard Imaging StructSure software was used to calculate the Dice similarity coefficient and to evaluate the differences in the volumes of the OARs.
        To evaluate the efficiency gain of each AI algorithm, automatically created structures were manually edited to clinically acceptable results and time required for completing that task was measured. There were some discrepancies between the datasets received by the different vendors (e.g. body contour was added only by MVision algorithm), therefore, missing structures were contoured manually and time was added to the editing task. Average time per patient was calculated for manual contouring and for the editing task for each vendor.
        The data used for training of MVision algorithm, includes prostate cases from NEMC (without femoral heads) although not the ones used for this study.

        Results
        Mirada Medical returned structure sets of 4 patients, MVision and TheraPanacea returned contours for all of the 5 patients. Table 1 shows both the accuracy of the different AI algorithms as well as the efficiency results. Bladder, rectum and prostate show highest accuracy results for all vendors (Dice 0.77-0.92). For prostate, MVision contouring tool systematically added extra contour on one CT slice above and below those outlined manually, which partly explains the larger volumes obtained. Largest differences in volume were observed amongst the femoral head contours, ranging from 31.64% smaller for MVision to 10.35% bigger for TheraPanacea compared to the manually contoured average volume. The larger difference for femoral heads could be due to the different definition of these structures in the AI training sets. For penile bulb, accuracy results are expectedly low due to its small volume, even a slight difference in contouring adds to a large difference in volume.
        TheraPanacea had the highest accuracy results and it reflects on 50.7% less time required for the delineation task, compared to manual contouring. Manual contouring took on average 43.14 min per patient. The use of MVision automatic segmentation algorithm reduced the contouring time by 20.5% and Mirada Medical reduced contouring time by 1.1%.

        Table 1. Accuracy and efficiency results for different AI algorithms compared to manually segmented structures. Average manual contouring time per patient is 43.14 minutes.
        /Table1/

        Conclusion
        All AI based contouring tools were able to reduce the contouring time. Smaller gain in efficiency for Mirada Medical might imply that different contouring protocols were used by the clinics that contributed to the development of the algorithm compared to the protocols followed by NEMC Radiotherapy Centre. The structure definition in the training set is important and could be used for harmonization of the contouring practices among different clinics. While the manual editing is still needed, AI based contouring can reduce the OAR delineation time significantly.

        Speaker: Anni Borkvel (NEMC)
      • 11:44
        Current opportunities and challenges in a period of 2D to 3D transition in Radiation therapy in Mongolia 7m

        The NCCM has taken number of measures to increase its diagnostic and therapeutic capacity by financial support of Ministry of Health, one of which was to build a three-storey expansion building with 5 bunkers for radiotherapy in 2009-2017 and an implementation of the project "Improving quality and access to cancer diagnostics and treatment" funded by soft loans of Austrian Government.
        Phase I project implemented through soft loans from Austrian government resulted in big advance in a history of radiation therapy in Mongolia which is an introduction of Linear accelerators first time in June 2019 and 3D conformal radiation therapy has become available.
        Up to this point, many efforts have been made and step-by-step measures have been taken to improve radiotherapy facility.
        i. 2006: Introduction of shaped Cerrobend blocks improved the protection of healthy tissues during radiation therapy
        ii. 2007: With the installation of SOMATOM Emotion 6 CT simulator for radiation therapy planning it became possible to accurately determine the location of tumor and nearby healthy organs and to plan volume based treatment.
        iii. 2010: With the introduction of CMS XiO 3 dimentional treatment planning system volume based calculations have become available
        iv. 1995 – 2006: In a part of quality control, quality control of radiation therapy equipment became available with the introduction of dosimetry system through the IAEA project.
        v. After receiving complete PTW dosimetry system the commissioning of radiation monitoring measurements for the installation of linear accelerators with automatic water phantom, as well as radiation monitoring and annual measurements of Cobalt-60 teletherapy units and linear accelerators were carried out in accordance with IAEA standards.

        Cervical cancer is the second leading cancer for women in Mongolia and patients with cervical cancer occupy 38% of patients undergoing radiation therapy. Over 200 cervical cancer patients receive Brachytherapy and about 800 applications are performed each year.
        Brachytherapy has reached its current level through the following steps:
        i. 2002: The installation of mobile C-arm unit has improved the quality of treatment by introducing brachytherapy x-ray image guidance.
        ii. 2010: With the installation of “Gynesource” brachytherapy unit it has become possible to accurately calculate treatment dose at the point in accordance with international standards using Manchester method of calculation.
        iii. 2018: Volume based accurate treatment calculation has been started with the introduction of CT based 3D technique.
        The successful implementation of this project will contribute towards national efforts to respond to the growing demand for radiotherapy in the country with the latest techniques and quality in line with international best practices and standards. We face following issues to solve:
        1. In order to further improve access to radiation therapy technological advancement in radiation therapy such as intensity modulated radiation therapy (IMRT), 4D gating, stereotactic body radiation therapy (SBRT) has to be introduced for reduced damage to normal tissue, enhanced quality of life for cancer patients and increased survival rate.
        2. Delayed building of Premise of linacs that caused warranty period to expire only after 1 year. It has been built with insufficient air circulation system,
        3. Commissioning: It was a first experience for medical physicists to commission our first linacs and it was a learning process at the same time. As a Member State of the IAEA since 1973, Mongolia has been closely involved with the Agency for decades, and it was one of many assistance that Mongolia has received in using nuclear applications to better the lives of its people.
        4. Mongolia also suffered some very significant exogenous shocks during the transition, including insufficient supply of some devices and applications of the linear accelerators
        5. Maintenance of equipment: as a landlocked nation located within the interior of a vast continent, Mongolia faces extraordinary challenges given by its topography. Sometimes it takes hours or days, even weeks to repair linear accelerators
        6. Along with introduction of new technologies and equipment, there is need to improve radiation control and protection, and safety practices in accordance with IAEA’s and other international standards and guidelines.
        Any transition period in implementing higher technology needs solid experience of its previous adopted technology and successful cooperation with international organization like IAEA with excellent experts would help us in safe introduction of new nuclear technology.

        Speaker: Minjmaa Minjgee (National Cancer Center of Mongolia)
      • 11:51
        Implementing compensator IMRT using Low Cost Effective Solution - A Zambian Experience 7m

        Kennedy Lishimpi, Lewis Banda, Susan C Msadabwe, Dorothy Lombe, Mulape Kanduza, Augustine N Mwale, Barbara C. M’ule, Anthony Sinalume, Ernest Chanda, Cain Chintala, Sha Chung, Catherine Mwaba
        Purpose IMRT is now the standard radiotherapy delivery mode. It was not available at the Cancer Diseases Hospital (CDH) of Zambia and many RT clinics in Low- and Middle-Income Countries. CDH has one Primus LINAC and two cobalt machines, all without MLC. There are two planning systems Oncentra External Beam and Brachytherapy and the Prowess planning system. CDH currently can deliver 3D EBRT and BT very well and has a mould room which is equipped to fabricate blocks and compensators and other immobilization devices. We report here our initial experience of implementing a recyclable compensator-IMRT solution. The solution is based on an in-house compensator-IMRT solution of the University of North Carolina that treated 1500 patients. We evaluated the feasibility of the IMRT solution from US in a LMIC clinic for clinical implementation.
        Methods The Government of the Republic of Zambia (MoH/CDH) and EmpowerRT signed a memorandum of understanding to bring the EmpowerRT solution to Zambia. The solution includes software (treatment planning software PLUNC and an eChart designed for manual operation clinics), hardware (milling machine and compensator fabrication materials), service (commissioning and local network setup), and training (software, QA, and procedures). The training consisted of weekly remote training and one onsite training to CDH physicists, radiation oncologists, and RTTs.
        Results EmpowerRT provided the 3D and IMRT commissioning of Primus Linac. The training included CDH staff teaching each other, a crucial step for us to make the solution our own. We found two PLUNC features particularly useful. Plan Comparison allows us to compare plans (i.e., a 3D and an IMRT) and make a clinical decision on which plan to use. Plan Motion-Effect shows the patient setup uncertainty on cumulative Dosimetry of a fraction treatment course. It allows us to use IMRT safely and sensibly as we do not have online imaging. We use standard immobilization devices. Estimated patient setup uncertainty is used to compute the cumulative dosimetry of an IMRT plan to determine if the IMRT plan safe to use. Our RTTs found EmpowerRT’s color-coding system (each block and compensator pair labeled with a unique color dot) easy to use and the compensator fabrication and QA procedures are easy to follow to constantly produce high quality compensators. We have done initial testing of eChart, a new product of EmpowerRT for clinics that still use paper charts. In PLUNC users can export to the eChart treatment prescription, machine parameters of each field, DRRs of setup and treatment fields, isodose distribution, DVHs, plan goal sheet, and other information. The eChart is not linked to our analog treatment machines that we operate manually but it highlights the field and its machine parameters to be treated next, records the actual MU/time delivered provided by RTT, computes the delivered total dose so far, and highlights any deviations. Both the eChart and PLUNC run on a server and available to all connected CDH computers.
        Conclusion It is feasible to implement EmpowerRT’s compensator-IMRT solution in Zambia using existing resources. The approach of training a trainer ensures local knowledge retention.

        Speaker: Kennedy Lishimpi (Cancer Diseases Hospital - Radiation Oncology)
    • 12:00 15:00
      Brachytherapy in the real world: Parallel Sessions: Refresher Courses

      Brachytherapy is a treatment modality that has been used for more than a century in the treatment of cancer. During golden age, the intrinsic properties of brachytherapy compensated the lack of conformation of external beam radiotherapy. In modern times, advances in the field of surgery and external beam radiotherapy have relegated brachytherapy to some niche indications. However, its role is still very relevant in many real-life indications and contexts.

      The goal of this RC is to give an overview of the main indications of brachytherapy, standard procedures and advanced technologies, quality assurance and safety and health economics considerations.

      Learning objectives:
      The learning objectives for this RC are:
      • To understand what are the main indications for brachytherapy
      • To understand how to transition from basic to more advanced brachytherapy techniques
      • To learn the basis of quality and safety in brachytherapy
      • To understand how brachytherapy can be used to reduce costs in radiotherapy

      Convener: Alfredo Polo (IAEA)
      • 12:00
        Status of Brachytherapy Worldwide: a DIRAC study 5m
        Speaker: Alfredo Polo (IAEA)
      • 12:05
        Health Economic Evaluation of Brachytherapy for cancer treatment 15m
        Speaker: Alfredo Polo (IAEA)
      • 12:20
        Technological advances in Brachytherapy -TPS, new sources, new applicators, AI 15m
        Speaker: Mauro CARRARA (IAEA)
      • 12:35
        Comprehensive Quality Management in Brachytherapy 15m
        Speaker: Daniel BERGER
      • 12:50
        Education and Training of New Generations of Brachytherapy Practitioners 20m
        Speakers: Mauro CARRARA (IAEA) , Supriya Chopra (Professor, Radiation Oncology, Tata Memorial Centre)
      • 13:10
        Omitting brachytherapy in gynecological cancer is deleterious for your patients 15m
        Speaker: Supriya Chopra (Professor, Radiation Oncology, Tata Memorial Centre)
      • 13:25
        Cervix Cancer as a Model for Image Guided Brachytherapy 15m
        Speaker: Umesh Mahantshetty (Professor, Radiation Oncology)
      • 13:40
        The migration from 2D to 3D and IGBT: implementation challenges 20m
        Speakers: Daniel BERGER, Umesh Mahantshetty (Professor, Radiation Oncology)
      • 14:00
        Leading the change: opportunities and challenges for brachytherapy in the management of cancer (Panel Discussion) 30m
        Speaker: Alfredo Polo (IAEA)
      • 14:30
        Practical Educational Session 20m
        Speakers: Daniel BERGER, Umesh Mahantshetty (Professor, Radiation Oncology)
    • 12:00 15:00
      Educational Milestones in the Profession of RTT: Parallel Sessions: Refresher Courses

      The learning objectives for the Educational Milestones in the Profession of RTT Refresher Couse are:
      1. To discuss the current status of RTT education worldwide
      2. To identify the challenges and future directions for the RTT profession

      Convener: Ms Michelle Leech (Trinity College Dublin, Ireland )
      • 12:00
        Current Status of RTT education globally 15m
        Speaker: Michelle Leech (Trinity College Dublin, Ireland )
      • 12:15
        The advancing and changing role of the RTT 15m
        Speaker: Aidan Leong (University of Otago, New Zealand )
      • 12:30
        Where are we going?: Future Directions for the RTT profession 15m
        Speaker: Mary Coffey (Trinity College Dublin, Ireland )
      • 12:45
        Panel Discussion: RT education, challenges and opportunities in the coming decade 40m
        Speakers: Aidan Leong (University of Otago, New Zealand ) , Colette Dijcks (Maastro Clinic, Maastricht Netherlands) , Gurvinder Singh Dhawan (Rajiv, Gandhi Cancer Institute and Research Centre, India) , John Ryan (RMIT University Australia) , Mary Coffey (European Society of Radiotherapy and Oncology) , Michelle Leech (Trinity College Dublin, Ireland ) , Samuel Opoku (University of Ghana, Ghana)
      • 13:25
        Break 1h 35m
    • 12:00 15:00
      Proton Radiotherapy: Parallel Sessions: Refresher Courses

      The learning objectives of this Refresher Course are:
      • To understand how the multidisciplinary proton team research, update and deliver state of the art proton therapy
      • To highlight conundrums that proton beam therapy presents in medical physics and radiobiology
      To review the specific role and evidence for proton therapy in the management of children with cancer

      Convener: Ms Karen Kirkby (Professor of Proton Beam Physics, University of Manchester, UK)
      • 12:00
        Does it work: Developing and implementing clinical trials of PBT 20m
        Speaker: Cai Grau (Aarhus University, Denmark)
      • 12:20
        Medical Physics Issues in Proton Therapy: Changing from 2 phases to single phase simultaneous integrated boost (to better use the optimiser) and use of EUD for plan assessment 20m
        Speaker: Matthew Lowe (University of Manchester, UK )
      • 12:40
        The patient-centred PBT pathway 15m
        Speaker: Vicky Hughes (The Christie NHS Foundation Trust, UK )
      • 12:55
        Image Guidance in proton therapy 15m
        Speaker: Katja Langen (Emory University, USA)
      • 13:10
        Dose Accumulation in Proton Therapy 15m
        Speaker: Tony Lomax (Paul Scherrer Institute, Switzerland )
      • 13:25
        FLASH proton therapy? 15m
        Speaker: Jack Aylward (Gloucestershire Hospitals NHS Foundation Trust, UK )
      • 13:40
        Paediatric Proton Therapy 20m
        Speaker: Thomas Merchant (St. Jude Children's Research Hospital, USA)
      • 14:00
        Break 1h
    • 12:00 15:00
      Radiation Oncology Education in the Interconnected World: Parallel Sessions: Refresher Courses

      The learning objectives of this Refresher Course are:
      1. To discuss the needs and innovative methods to integrate perspectives and skills for international collaboration and advocacy roles into radiation oncology education
      2. To share best practices on the integration of oncology education and research
      3. To discuss the value of interprofessional education and propose innovative educational methods to teach and assess interprofessional collaboration skills
      4. To discuss various initiatives to strengthen radiation oncology through world-wide education

      Conveners: Mr Jesper Grau Eriksen (Aarhus University, Denmark) , Ms Sandra Turner (The University of Sydney, Australia)
      • 12:00
        Global health competencies in radiation oncology education 15m
        Speaker: Meredith Guiliani (University of Toronto, Canada)
      • 12:15
        Integrating radiation oncology education and research 15m
        Speaker: Miriam Mutebi (Aga Khan University Hospital, Nairobi, Kenya )
      • 12:30
        Interprofessional education 15m
        Speaker: Michelle Leech (Trinity College Dublin, Ireland )
      • 12:45
        Strengthening Networks in Worldwide Radiation Oncology Education: HIC Perspectives 15m
        Speaker: Daniel Golden (UChicago Medicine, USA)
      • 13:00
        Strengthening Networks in Worldwide Radiation Oncology Education: LMIC Perspectives 15m
        Speaker: Lotfi Kochbati (Institut Salah-Azaïz de Cancerologie, Tunisia)
      • 13:15
        Panel Discussion: Strengthening Networks in Worldwide Radiation Oncology Education 45m
        Speakers: Daniel Golden (UChicago Medicine, USA) , Jesper Grau Eriksen (Aarhus University, Denmark) , Lotfi Kochbati (Institut Salah-Azaïz de Cancerologie, Tunisia) , Meredith Giuliani (Princess Margaret Cancer Centre) , Ms Michelle Leech (Trinity College Dublin, Ireland ) , Sandra Turner (The University of Sydney, Australia;)
      • 14:00
        Break 1h
    • 12:00 15:00
      Technological developments in radiation therapy practice: Parallel Sessions: Refresher Courses

      The learning objectives for this Refresher course on Technological developments in radiation therapy practice are:
      1. To discuss the impact of new technologies on the development of the RTT profession;
      2. To discuss the changing role of the RTT in meeting the challenges of rapid technological developments.

      Convener: Ms Michelle Leech (Trinity College Dublin, Ireland )
      • 12:00
        A changed set up?: Implementation of surface guided radiation therapy 15m
        Speaker: Kenton Thompson (Peter MacCallum Cancer Centre, Australia)
      • 12:15
        Advancing and changing practices: bringing the MRI-linear accelerator into clinical reality 15m
        Speaker: Veronica Pollutri (Fondazione Policlinico Universitario "A. Gemelli", Italy)
      • 12:30
        Proton therapy- new directions in treatment delivery for RTTs. 15m
        Speaker: Sharon Wong (Singapore Institute of Technology, Singapore )
      • 12:45
        Panel Discussion: The Impact of New Technologies and the Changing Role of the RTT Profession 40m
        Speakers: Helen McNair (The Royal Marsden NHS Foundation, UK) , Michelle Leech (Trinity College Dublin, Ireland ) , Nicola Bizzochi (Paul Scherrer Institute, Switzerland) , Sharon Wong (Singapore Institute of Technology, Singapore) , Veronica Pollutri (Fondazione Policlinico Universitario "A. Gemelli", Italy)
      • 13:25
        Break 1h 35m
    • 15:00 15:30
      e-Contouring Workshop: SABR for Lung Cancer 30m
      Speaker: Billy Loo (Stanford University)
    • 15:30 16:00
      e-Contouring Workshop: Prostate Cancer 30m
      Speaker: Mr Mack Roach III (Professor Departments of Radiation Oncology & Urology University of California, San Francisco)
    • 07:45 08:15
      Brachytherapy

      Learning objective(s):
      Discuss the role of brachytherapy in modern radiation oncology
      Identify challenges and future directions

      • 07:45
        Clinical relevance of brachytherapy in the global oncological landscape 30m
        Speaker: Christine Haie-Meder (Gustave Roussy Cancer Center)
    • 08:15 09:00
      Translational Radiation Biology

      Learning objective(s):
      To review advances in translational radiation biology and their applications in radiation oncology

      • 08:15
        Radiobiology of High Dose per Fraction 30m

        The goal of this keynote lecture is to present an overview of the rationale and pitfalls of hypofractionation from the perspectives of radiobiology

        Speaker: Mike Joiner (Wayne State University School of Medicine, MI, USA)
      • 08:45
        Recent Developments in Radiobiology 15m

        The goal of this lecture is to present an overview of contemporary radiobiology, the main indications and available technologies, and the best practices for the implementation of radiobiological findings in radiation oncology.

        Speaker: Loredana Marcu (Faculty of INFORMATICS & Science, University of Oradea, Romania CANCER RESEARCH INSTITUTE, University of South Australia, Australia)
    • 09:00 09:30
      Education and Training

      Learning objective(s):
      Discuss challenges and future directions of competency-based radiation oncology education

      • 09:00
        Competency Based Education in Radiation Oncology: Global Perspectives on the Assessment of Learning 30m

        The Keynote Lecture will discuss recent developments and challenges in the assessment and certification aspect of radiation oncology education globally. The goal is to disseminate best practices and invite discussion towards the assessment of learning at the global level.

        Speaker: Kim Benstead (Gloucestershire Hospitals NHS Foundation Trust , UK )
    • 09:30 10:00
      The RTT Profession

      Learning objective(s):
      Identify the need to advance the education of radiation therapists worldwide
      Discuss challenges and solutions

      • 09:30
        The RTT Profession 30m

        The keynote lecture will look to identify the need to advance the education of radiation therapists worldwide and discuss challenges and solutions.

        Speaker: Mary Coffey (School of Medicine - Trinity College Dublin, Ireland)
    • 10:00 10:30
      Clinical Research

      Learning objective(s):
      Describe challenges and solutions in ensuring equity in radiation oncology research
      Identify solutions to increase participation of LMICs in clinical research

      • 10:00
        Clinical Research 30m

        The keynote lecture will describe the challenges and solutions in ensuring equity in radiation oncology research: as well as identifying solutions to increase the participation of LMICs in clinical research.

        Speaker: Jai Prakash Agarwal (Tata Memorial Hospital, India)
    • 10:30 11:00
      Health Systems Research

      Learning objective(s):
      Describe the concept and application of health systems research
      Discuss the importance of health systems research in addressing the issue of access and sustainability

      • 10:30
        Health Systems Research 30m

        This keynote lecture will describe the concept and application of health systems research; and will discuss the importance of health systems research in addressing the issue of access and sustainability

        Speaker: Yolande Lievens (University Hospital Ghent, Belgium)
    • 11:00 11:30
      Paediatric Radiotherapy

      Learning objective(s):
      Discuss challenges in the management of teenage and young adults with cancer
      Identify directions to improve treatment outcomes with radiotherapy

      • 11:00
        Radiotherapy in Teenagers and Young Adults with cancer: Providing Care and Improving Outcomes 30m

        This keynote lecture will discuss the challenges in the management of teenage and young adults with cancer and
        identify directions to improve treatment outcomes with radiotherapy.

        Speaker: Ed Smith (The Christie NHS Foundation Trust, UK)
    • 11:30 12:05
      Paper Session 3: Health Economics and Health Systems Research

      Session for the presentation of Oral presentations on Health Economics and Health Systems Research

      • 11:30
        Revitalizing and strengthen the capacity of cancer management in Cambodia: Past-Present and future involvement of multi-stakeholders. 6m

        Not only after 2003 that the installation of a Cobalt machine with the efforts of Cambodian Government and the French NGOs (Physiciens san Frontière and Cancérologue sans Frontière), an oncology department has reopened again at (Khmer-Soviet Friendship Hospital) to serve Cambodian population suffering from cancers. Alongside with the medical equipment and facilities, the need in term of the competent medical staffs are in a priority for helping policy. Due to the recent data estimated by Globocan 2012, there were at least 15116 new cases of cancer patients in Cambodia. With a population of 16 million and the huge number of new cancer cases, at least 60% of cancer cases might need more radiation therapy facilities. Under support of health policy, National Strategic Plan 2008-2015 for Non-Communicable Disease and with the recommendation of imPACT mission report by the International Atomic Energy Agency in 2013 and Country Program Framework 2017-2023, has triggered stakeholders to get involved. A proposal made since 2013 and submitted to the World Bank via the Second Health Sector Support Project (HSSP2) of the Ministry of Health to support upgrading the radiotherapy unit at the department of oncology at Khmer Soviet Friendship Hospital, a non-profit healthcare institution affordable for poor people. The new radiotherapy machine using 6MV Linear Accelerator is now treating 40-45 patients per day and it replaced the old Cobalt 60 unit since March 2016. At the same time with efforts of the Cambodian government, Ministry of Health, and under the funding and technical support from the IAEA (Technical Cooperation), a new National Cancer Cancer was established since January 2018. For the perspectives to achieve sustainable success, the situation indicates that; the need for human resources (for better functioning of the cancer centers as well as to create a hub of local academic degrees for medical specialists, medical physics and radiation therapy technologies) with standard quality in the field of radiation therapy will play a crucial role in term of the current and future improvement of cancer management in Cambodia. So far, Stakeholders including National Hospitals, Medical universities and the TC program of the IAEA since 2012-2021, NGOs play major roles in capacity building of medical professionals, enhancing cancer center facilities to the need of Cambodian people which follow the recommendation of United Nations’ Millennium goals of sustainable development.

        Speaker: Socheat Touch (Khmer Soviet Friendship Hospital-University of Health Sciences)
      • 11:36
        The basic situation of radiotherapy in mainland China:a national survey in 2019 6m

        Purposes: To investigate the basic situation of radiotherapy in all hospitals of mainland china and provide a basis for developing radiotherapy standard.
        Methods: From Apr. 10th, 2019 to Sep. 20th, 2019, the 9th national survey on radiation oncology departments was conducted by Chinese Society of Radiation Oncology (CSTRO) of Chinese Medical Association. The investigation method was adopted with the electronic questionnaire which required the information about the staffs, devices, techniques, annual person-times of radiotherapy and the treated tumor sites.
        Results: All 1463 radiation oncology departments answered the questionnaire in mainland. The number of radiation department increased rapidly from 264 in 1986 to 1413 in 2015, and steadily from 2015 to 2019 owing to the reduction of the military hospital. The provinces of Shandong, Henan and Jiangsu got the largest number of radiation department in mainland China with 180, 149 and 106 departments, respectively. A total of 29096 staffs were employed, including 14575 clinical radiation oncologists, 8940 technical therapists, 4172 physicists, and 1409 maintenance engineers. The number of radiation oncologists increased from 1715 in 1986 to 16301 in 2015, however decreased to 14575 in 2019 due to the compulsory resident program in 2015. As the report of Chinese Medical Doctor Association, the number of residents in radiation oncology were 1209, 1316, 1353 and 1365 from 2015 to 2018. All other radiation personnel raised rapidly with the decreasing ratio of physician to physicist from 9.53 in 1986 to 3.51 in 2019. The rate of senior physicist was up to 51.9% in 2019, however, the rate of senior therapist was only 33.1%. In the aspect of radiotherapy equipment, there were 2021 linear accelerators, 66 Cobalt-60 teletherapy units, 339 brachytherapy units, 5 photon or heavy ion units, 1453 X-ray simulators, and 355 CT simulators. The number of accelerator and Co-60 per million population was 1.5, lower than the 2-4 according to the WHO standard. Beijing, Shanghai, and Shandong provinces fulfilled the WHO request with 3.73, 2.54 and 2.35, respectively. Yunnan, Guizhou, and Ningxia provinces were far below the WHO requirement with less than 1. However, the number of accelerator and Co-60 per million population were 1.04 and 1.07 in the economically developed provinces like Guangdong and Zhejiang. In this survey, three-dimensional conformal radiotherapy technique, intensity-modulated radiotherapy, stereotactic surgery or stereotactic body radiotherapy and Tomotherapy were more conducted in 1272 (86.9%) radiation departments in 2019 than 70.6% in 2015, 1121 (76.6%) than 50.1%, 297 (20.3%) than 16.3%, and 38 (2.6%) than 1.1%, respectively. Only 5 department had or were going to conduct the proton or heavy ion radiotherapy. The number of patients receiving radiotherapy reached 1259602 per-year accompany with the 37.0% increase compared with 919339 per-year.
        Conclusions: There is a slowly increase of radiotherapy units, personnel, and equipment in, as well as radiotherapy personnel and equipment which are far less than the requirements of World Health Organization. The disequilibrium exists in mainland China, even in the economically developed provinces

        Speaker: Junlin Yi (National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences)
      • 11:42
        Competences of Medical Dosimetrists and Radiation Therapy Technologists working in a Costa Rican Radiotherapy Department: A benchmarking approach to the recommended ESTRO Core Curriculum using a Training/Competency Matrix 6m

        Abstract

        Introduction: The European Qualification Framework (EQF) published a definition of competency, it means the proven ability to use knowledge, skills and personal, social and methodological abilities, in work or study situations and in professional and personal development. In the context of the EQF, competency is described in terms of responsibility and autonomy. The literature identifies various competences required for Medical Dosimetrists (CMD) and Radiation Therapy Technologists (RTT), however, these are varied and scattered among different publications. The aim of this study was to identify the actual competences of CMD and RTT practicing on treatment planning (TP) with tri-dimensional conformal (3DC) or intensity modulated (IM) radiation therapy (RT) and linear accelerator (LINAC) respectively, and their future training needs in Hospital San Juan de Dios Radiotherapy Department (RT-HSJD) according to a benchmarking approach over the recommended ESTRO Core Curriculum for RTTs.
        Methods: The recommended ESTRO Core Curriculum for RTTs was scrutinized for competences practiced by CMD and RTT. A systematic approach was performed by direct observation of the CMD and RTT daily practices to find relevant competences and training needs. A thematic analysis was performed to organize the competences according to themes. The themes described vary with regard to how technical and how specific the competences are to the CMD and RTT.
        Technical competences are those required to perform a specific job (or group of jobs) and are aligned with the autonomous and responsible application of knowledge and skills in specialized fields such as radiation therapy. These are complemented by non-technical competences (“soft skills”) which can be applied to several professions.
        The themes analyzed were: 1) Non-technical competences (Quality and risk management, Decision making and critical analysis, Management and leadership, Team work and multi-disciplinarity, Communication). 2) General technical competences in RT (Professionalism, Patient Care, Research, Education, Equipment quality assurance, File verification). 3) Technical competences in TP (Simulation, Contouring, 3DCRT-TP, IMRT-TP, Planning quality assurance). 4) Technical competences in LINAC (Positioning and immobilization, Delivery of treatment, Verification of patient setup, IGRT Image Verification).
        Then, a Training/Competency Matrix (T/C-M) was created to identify the relationship of the competences and the actual level achieved by each CMD and RTT in the RT department (Table 1). The competency level was set in the following qualifications: Great competency, autonomy and can teach others (4 points, purple color), Advanced competency and independent decision making (3 points, green color), Basic competency and dependent decision making (2 points, light blue color), In training (1 point, orange color) and Needs training (0 points, red color).
        Results: The actual level, distribution and results achieved by each CMD and RTT in RT-HSJD can be observed in Table 1. A T/C-M is a tool used to document and compare the required competences for a position with the current skill level of the employees performing the role. It is used in a gap analysis for determining where an organization have critical training needs and as a tool for managing people development. It can also be used in succession planning as a means of identifying employees who have critical skills needed for promotion. The multiple competences of the CMD and RTT described, encompass multiple themes and it’s an evidence of the complexity of the role of these professionals.
        Conclusion: The T/C-M provides a comprehensive view of all the skills and behaviors needed in a RT department. Aids in managing the training budget because it identifies skill gaps across the organization rather than just one person at a time. Assists with planning by helping identify and target new skill areas that RT departments might need for the long term. Helps managers with development planning by providing a framework of common skills required.
        The RT-HSJD has only two of nine fixed employees with professional training and they summarizes the highest competency levels (Table 1). Both has a Licentiate degree in Diagnostic Imaging and Radiotherapeutics from the University of Costa Rica (LIC-IDT-UCR) with specific training in Radiation Oncology, the other team members are radiographers with empiric training in this specialized area. The actual CMD and RTT across RT-HSJD must be formal trained to bridge the gap with professional standards or recommendations published such as the ESTRO Core Curriculum for RTTs and ensure the best care possible is given to patients. This study also promotes and emphasizes in the importance to incorporate professionals on CMD and RTT roles, as the ones with LIC-IDT-UCR.

        Speaker: Jorge Andres Villalobos-Rosales (CCSS-HSJD / UCR / ICAP)
      • 11:48
        Closing the Radiotherapy Gap in Indonesia: Reflection on National Roadmap Program 6m

        Introduction: Cancer has been increasingly become a burden in the world, particularly in developing countries such as Indonesia. Based on GLOBOCAN 2018, Indonesia cancer cases is expected to rise from 348,809 to 575,814 in 2040 or a 65.1% increase. Moreover, cancer attributable deaths will also spike up 76.9% from 207,210 to 366,567 deaths in 2040. Out of those number, the five most prevalent cases are breast, cervix uteri, lung, colorectum and liver. There are three mainstay treatments for cancer, including surgery, radiotherapy and chemotherapy. As one of the mainstay treatments, radiotherapy is an essential part of cancer management. It is estimated that around 50% of cancer patients need this type of treatment. Looking into the number of cancer cases in 2018, around 174 thousand cancer patients need radiation therapy. This number of cancer cases can be translated into 343 machines needed for the treatment of cancer using conventional fractionation. Using hypofractionation strategy, it is estimated that 268 teletherapy machines are needed. Talking about teletherapy machines needed per million population, Indonesia with over 270 million population, if 1 MV is needed for every 1 million population, 270 teletherapy machines are needed to ensure radiation treatment for every Indonesian citizen. Currently, RT machines available across the country only covered 34.7% of the country’s needs (using hypofractionation strategy). This study aims to present the reflection on Indonesian Radiation Oncology Society (IROS) national roadmap program to close the gap of radiotherapy services in Indonesia.
        Methodology: Roadmap of Indonesia radiotherapy services were established in 2010 for the escalation of radiotherapy services. Moreover, this roadmap was updated every 5 year to calculate the accomplishment of the projected outcome. Further update is conducted in certain year whenever needed, especially if newest available data is needed for advocacies.
        Results: These 5 yearly programs were divided into 9 different regions in Indonesia, each consisted of several provinces with different aims on the number of teletherapies needed. The rationalization on calculating the number needed are based on the number of populations, developing and archipelagic setting of the country, integration with national cancer control plan, cancer awareness among citizen, health promotion and continuing medical education for health professionals (especially oncologists). Multidisciplinary approach and guideline should also be obeyed by all oncologists to increase the utility of radiation therapy. Due to the circumstances that not all the criteria are able to be fulfilled, the society decided that this program aims to achieve 189 teletherapy machines by the end of 2035, or around 70% of 268 machines needed based on hypofractionation strategy calculation.
        Currently, this program has reached the second 5-yearly evaluation. By the end of 2020, is is projected that 94 RT machines will be available in Indonesia with five out of nine regions that have fulfilled the target needed by 2020. From table 1, we can see that most teletherapies are available in region 3 (DKI Jakarta, West Java and Banten) and region 4 (Central Java and Jogjakarta). However, despite being set up from 2010, there is one region (Maluku and Papua) which has no teletherapies at all.
        Conclusion: Cancer is an emerging problem in Indonesia. Radiation therapy plays a great role as one of the mainstay treatments for cancer, but the number of teletherapies is far from the needs. IROS has set up the 5-yearly roadmap for radiotherapy from 2010 to 2035 to scale up and fulfill the demand. By the end of 2020, some region is expected to meet the radiotherapy demand for the second program, but efforts are needed for the rest of the region, especially in the East part of Indonesia. To fill up the disparities across countries, multiple advocacies from the society to national and local government or private sectors have been conducted. This roadmap of radiotherapy has been given to the stakeholders in the Ministry of Health and incorporated into the National Cancer Control Plan (2015-2019). Further set up of the radiotherapy program has also been done with private hospitals or investors through public-private partnership framework (build operate transfer or joint cooperation). Additionally, to increase the utility of radiotherapy, setting up radiotherapy program should integrate multidiscipline and involve stakeholders. Nevertheless, in 2020, due to the pandemic problem of COVID-19 infection across the country, there might be some delay in fulfilling the demand of radiotherapy services in Indonesia.

        Speaker: Soehartati A Gondhowiardjo (Faculty of Medicine, Universitas Indonesia – Department of Radiation Oncology, Dr. Cipto Mangunkusumo National General Hospital – Jakarta, Indonesia)
      • 11:55
        Weighted Goal Programming Approach for Solving Budgetary Radiation Therapy Treatment 6m

        I.INTRODUCTION
        In today’s fast paced and competitive era of healthcare service provision, optimal allocation of budgeted expenditure poses a critical concern among patients under radiation therapy treatment. In this study, a goal programming model was developed to allocate budgetary expenditure for radiation therapy of inpatients at a medical facility. The relevant components of budgetary expenditure considered included drugs/materials, labor and miscellaneous costs. In order to test the proposed model, data for budgetary expenditure was obtained on a monthly basis at Mulago Cancer Institute in Uganda. The study primarily examined cost requirements for two categories of patients. Category 1 patients showed symptoms of initial stages when cancer had just spread to nearby tissues of the body. Category 2 patients had the spread of cancer to several parts of the body.
        2. METHODOLOGY
        A weighted goal programming model is developed and initially, the objective function is defined. The model seeks to minimize the deviation variables of the objective function.; subject to the goal values of budgetary expenditure allocated for treating category 1 and category 2 patients. The sum of weighted deviations is minimized so that actual expenditure on drugs/materials, labor and miscellaneous costs meets the projected expenditure. Resource leveling is achieved by using the simplex method for linear goal programming; that requires solving the standard minimization problem. A numerical example is presented for illustration; that determines the optimal allocation of expenditure on drugs/materials, labor and miscellaneous costs for inpatients under radiation therapy treatment.
        3. RESULTS
        Results from the numerical example presented indicate that certain goals on drugs/materials, labor and miscellaneous costs can be fully or partially achieved. This however depends upon the priority levels and targets set for budgeted expenditure; in line with the two categories of patients under treatment. The application of this solution approach allows hospitals to identify satisfactory allocation of expenditure; based on the priority levels or goals set for meeting budgetary projected costs during radiation therapy treatment among patients.
        4. CONCLUSION
        The weighted goal programming approach for inpatient radiation therapy can be effective; where relevant cost categories can be prioritized if necessary. This ensures cost-effective medical treatment in hospitals; a core ingredient of sustainable healthcare service provision.

        Speaker: Kizito Mubiru (Kyamboto University)
    • 12:06 12:30
      Paper Session 4: Radiobiology

      Session for the presentation of Oral presentations on Radiobiology

      • 12:06
        NTCP and estimation of secondary cancer risk in Modulated Arc Therapy for prostate carcinoma using in-house software. 6m

        NTCP and estimation of secondary cancer risk in Modulated Arc Therapy for prostate carcinoma using in-house software.

        1A.Boughalia, 2M.Fellah, 3 Ben Amirouche, 3A.Nekaa

        1Medical Physics Department, Nuclear Research of Algiers, Algeria
        a.boughalia@crna.dz
        2Physics Faculty, Houari Boumedienne University Bab Ezzouar Algiers, Algeria
        Fellahm1@yahoo.fr
        3Radiotherapy Oncology Department, Fatima El Azhar Centre Dely Ibrahim, Algiers, Algeria
        a.nekaa@cliniquealazhar.com
        benamirouche@ cliniquealazhar.com

        Introduction of the study
        This study evaluates the toxicity for organs-at-risk and estimates the secondary cancer risk from Volumetric Modulated Arc Therapy for a cohort of prostate carcinoma patients using in-house software (Coupôle).

        Methodology
        A cohort of twelve patients was treated with 76 Gy using daily 2Gy fractions. The 18 MV (Elekta) treatment was planned using the Monaco TPS.
        Normal tissue complication probability (Lyman-Kutcher-Burman) and secondary cancer probability (linear model rectum: α1=0.017,α2=0.25 and (α/β)=4.5; bladder: α1=0.006,α2=0.25 and (α/β)=7.5) were calculated for rectum and bladder using in-house software and the NTCP values were compared to those obtained with Biosuite.

        Results
        The mean NTCP for rectal bleeding (grade≥2) was 7.14% (range 4.38-9.72%) obtained with Coupôle versus 7.50% (range 4.2-10.1%) with Biosuite and for fecal incontinence we have obtained 5.43 % (range 3.7-7.3) versus 5.33% (range 3.66-7.15) respectively. The estimated risk for secondary cancer is 1.30% for rectum and it was 0. 73% for bladder. Regarding the risk for secondary malignancies, the VMAT plans showed the highest values for both rectum and bladder for certain patients of studied cohort.

        Conclusion
        Our in-house software Côupole was valdated against Biosuite; twelve prostate treatment plans were evaluated in terms of toxicity and second cancer risk. Evaluation of NTCP and second cancer estimates can improve treatment quality, particulary when complex treatment modalities are involved.

        Keys words: NTCP, secondary cancer risk, rectum, bladder, VMAT, prostate carcinoma.

        Speaker: Assya Boughalia (Medical Physics Department, Nucleaire Research of Algiers)
      • 12:12
        Neutron Capture Enhanced Particle Therapy (NCEPT): In vitro proof of concept 6m

        Introduction

        Neutron Capture Enhanced Particle Therapy (NCEPT) is a novel adjunct to proton and heavy ion therapy, which enhances the radiation dose delivered to a tumour relative to surrounding healthy tissue by capturing thermal neutrons produced during ion irradiation. NCEPT utilises $^{10}$B and $^{157}$Gd-enriched tumour-specific neutron capture agents presently approved or in development for neutron capture therapy. NCEPT improves tumour control by increasing the dose to the target volume, while reducing the normal tissue complication probability by reducing the primary radiation dose, hence reducing the radiation dose to normal tissue. Additionally, NCEPT can target nearby satellite lesions outside of the primary treatment volumes with a therapeutic dose. In this work, we report the outcome of three successful rounds of in vitro experiments, conducted at the National Institutes for Quantum and Radiological Science and Technology (NIRS, QST) Heavy Ion Beam research facility, which have provided the first experimental proof of concept for NCEPT.

        Methodology

        Experiments were conducted at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan in July 2018, February 2019 and February 2020. T98G (human glioblastoma) cells were cultured in T25 flasks and inserted into a 300 mm cube of PMMA, such that the cell layer was positioned at the middle of the depth range of the spread-out Bragg peak and normal to the the beam. Two flasks were located within the planned target volume, with a further two flasks laterally offset such that they were just outside of the target volume (one on the left and one on the right). The cells were then irradiated with polyenergetic beams of either $^4$He or $^{12}$C (100 mm $\times$ 100 mm $\times$ 60 mm SOBPs).

        Flasks placed in the two middle positions received a heavy ion dose of 0 to 10 Gy, with or without pre-irradiation treatment with the neutron capture agents (NCAs) $^{10}$B-BPA and $^{157}$Gd-TPP-DOTA. The two flasks outside of the primary target volume were used evaluate the effect of NCEPT on satellite lesions (since the neutron field extends well beyond the target volume). The effects of irradiation on cell proliferation and survival with and without the NCAs, both inside and outside the target volume, were quantified using the Resazurin Cell Viability Assay and clonogenic assay.

        Additionally, the effect of NCA concentration on the efficacy of NCEPT in-beam (in the middle of the SOBP), both for $^{10}$B-BPA and $^{157}$Gd-TPP-DOTA was assessed for $^4$He or $^{12}$C ion beams, with a fixed radiation dose of 3 Gy.

        Results

        Dose responses obtained via clonogenic assay for both NCAs and ion species are shown in Figure 1(a). A progressive reduction of cell viability in response to dose escalation (0 to 10 Gy) can be observed. A dramatic reduction in cell viability is observed at doses exceeding 2 Gy. The dose at which 50\% reduction in cell mass is achieved (IC50) was also estimated for carbon and helium ion therapy, with and without the presence of NCAs. To achieve a 50\% reduction in the mass of viable cells treated with carbon and helium ions alone, 3.1$\pm$0.1~Gy and 3.54$\pm$0.4 Gy are required, respectively. The addition of $^{10}$B-BPA and $^{157}$Gd-TPP-DOTA reduces the IC50 dose by 42\% and 68\%, respectively.

        Concentration response results are shown in Figure 1(b). At a primary carbon and helium ion dose of 3 Gy, 100-250 uM concentrations of both NCAs are sufficient to obtain a reduction in viable cell mass comparable to 8 Gy of carbon and 10 Gy of helium ion irradiation in the absence of the NCA. Concentrations in excess of approximately 10 uM are sufficient to obtain a measurable decrease in viable cell mass.

        Out-of-field dose responses are shown in Figure 1(c). A very strong (and approximately linear) response to escalating primary ion dose is observed out-of-field with both ion species and NCAs. Without the presence of the NCA, the impact on cell viability outside of the primary treatment volume is minimal (less than 20% reduction in viable cell mass at 10 Gy primary dose, compared to more than than 95% reduction in the presence of NCAs.

        Conclusion

        The effectiveness of NCEPT on cell cultures inside and adjacent to the target volume has been evaluated. NCEPT achieves substantial reductions in T98g cell viability with both boron and gadolinium-based neutron capture agents in the target volume compared to untreated control cell cultures subjected to an equivalent primary radiation dose. Although cells outside of the primary target volume receive little dose from the heavy ion beam, the addition of neutron capture agents to these cells also results in a substantial reduction in cancer cell viability. This is due to the extension of the thermal neutron field beyond the target volume. The next steps for NCEPT include (1) evaluating NCEPT in vitro with proton therapy and (2) in vivo evaluation of NCEPT for heavy ions and protons using both neutron capture agents.

        Speaker: Mitra Safavi-Naeini (Australian Nuclear Science and Technology, ANSTO)
      • 12:18
        MECHANISM-BASED COMBINATION THERAPY IN CANCER: STUDIES ON CANCER CELLS 6m

        Telomeres play a critical and opposing role in the process of carcinogenesis, serving as an obstacle e during early stages of cell transformation and later a cancer hallmark for unlimited cell proliferation. . Reactivation of telomerase is essential for telomere maintenance in human cancer cells ensuring indefinite proliferation. Targeting telomere homeostasis has become one of the promising strategies in the therapeutic management of tumours. We have recently shown that inhibition of DNA repair factors and telomerase renders cells more sensitive to DNA damaging agents. In addition to inducing telomere dysfunction, inhibition of telomerase decreased tumour cell viability, induced cell cycle arrest and DNA damage. The observed therapeutic potential in the cancer cells improved when they were combined with the inhibition of certain selective DNA repair factors such as poly(ADP-ribose) polymerase-1, DNA-depndent protein kinase (DNA-PKcs), Ataxia Telangiectasia Mutated (ATM) and/or radiation. Interestingly, telomerase inhibitors impede the cell survival and proliferative ability to a greater extent in telomerase-positive cells as compared to alternative lengthening of telomeres-positive cells both in acute and chronic treatments. In addition, our in vitro studies suggest that inhibition of DNA repair pathways and that of telomerase could sensitise cancer cells to radiation and enhance anti-tumour effects. Taken together, our in vitro studies in cancer cells demonstrate that inhibition of DNA repair pathways and that of telomerase could be an alternative strategy to enhance anti-tumour effects and circumvent the possibility of drug resistance.

        Speaker: Manoor Prakash Hande (National University of Singapore)
      • 12:24
        Concomitant boost in preoperative irradiation of rectal cancer 6m

        The question of delivery of concomitant boost – additional small dose about 0.3 Gy locally to the tumor in the same fraction of external irradiation - is still under consideration. It was discussed in the literature from time to time. Especially it concerns the irradiation of rectal cancer. An obvious obstacle to this regime of irradiation is the additional time spent on an additional planning involving medical physicist and radiotherapist and additional load on the accelerator. Nevertheless, the analysis of the results in comparing of the treatment with and without concomitant boost could be of help in gaining deeper knowledge in radiobiology of tumor response to different regimes.
        The aim of the work was to evaluate tumor regression after irradiation of the rectum cancer with and without additional dose 0.3 Gy locally in the same radiation session.
        Groups of the patients. 39 patients with confirmed colorectal cancer and the same clinical status have been involved into the study.
        Colonoscopy has been performed followed by histological analysis.
        In CT and MRI studies pathological lymph nodes in the iliac region have been diagnosed in 22 patients (N1-N2), in 17 patients the affected lymph nodes were absent at CT/MRI studies.
        In all patients, histological examination confirmed squamous cell carcinoma. No distant metastases were detected (M0).
        Patients were divided into two randomized groups.
        The first group before the operation received 2 Gy for the small pelvis by opposite fields up to 46 Gy. In the second group after delivery of 1.8 Gy to the small pelvis by opposite fields, rectum was irradiated locally by three fields technique up to 0.3 Gy.
        The dose was administered over 23 fractions 5 times per week. Thus, in the second group, the pelvis received 41.4 Gy and the rectum – 52.9 Gy respectively.
        Supportive care was the same in the first and the second groups. 5-FU with the aim of immunomodulation was prescribed in both groups according to protocol.
        Results. The degree of tumor response was assessed by comparing CT/MRI scans before irradiation and two weeks after it. Surgical evaluation of treatment outcomes was also taken into account. From the side of critical organs, there was no difference in the number of reactions to irradiation in both groups. Vomiting, frequent urination, problems with bowel emptying in a percentage value was actually equal in both groups. About 75 % of patients in both groups experienced discomfort with the indicated symptoms during the treatment period.
        Nevertheless patients in the second group not reliably were in a better state during irradiation.
        In the first group where patients received standard fractionation, the degree of tumor regression amounted to 20 % of the initial volume in average (from 0 to 55 %). In the second group – up to 40 % on average (from 0 to 80%). In the independent assessment of surgeons it was indicated that the second regime with additional dose was preferable. It is interesting to note that we used concomitant boost in not-operable patients with brachytherapy followed external irradiation. It was based on more tumor regression in concomitant boost treatment. It facilitates brachytherapy. In the case of the large tumors it is necessary to introduce needles into the pararectal zone for appropriate tumor irradiation. And in the case of sufficient tumor response, it is enough to indicate intracavitary brachytherapy with standard normalization 0.5 cm from the mucous.
        Conclusion. Concomitant boost (0.3 Gy additionally to 1.8 – 2 Gy) in preoperative irradiation of rectal cancer results in more significant tumor regression compared with the standard fractionation. Patients tolerate this regime with the same degree of radiation reactions as in standard fractionation.
        Concomitant boost can be used before brachytherapy giving the possibility to irradiate tumor intracavitary in the case of essential tumor regression.

        Speaker: Elena Yermilova
    • 12:30 14:30
      Advanced Technologies / Beyond 3D: (Parallel Sessions: Refresher Courses)

      The learning objectives for this Refresher Course are:
      • To understand the basic principles of advanced radiotherapy techniques
      • To understand how to transition from basic to more advanced radiotherapy techniques
      • To learn the basis of quality and safety in advanced radiotherapy
      • To understand the cost-benefit of advanced radiotherapy

      • 12:30
        Multimodality imaging and deformable image registration 20m
        Speaker: Vincenzo Valentini (Gemelli, Universita Catolica del Sacro Cuore, Italy)
      • 12:50
        Automated target volume / organs at risk delineation and treatment planning 20m
        Speaker: Vincent Gregoire (ICRU, University Catholique de Louvain, Belgium)
      • 13:10
        Management of interfraction motion (IGRT, Adaptive RT) 20m
        Speaker: X. Allen Li (Medical College of Wisconcin, USA)
      • 13:30
        Advances in dose delivery (MRI linac, transponders, FLASH...) 20m
        Speaker: M. Saiful Huq (University of Pittsburgh, School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, United States of America)
      • 13:50
        Break 40m
    • 12:30 14:30
      Expanding Access to Radiotherapy: (Parallel Sessions: Refresher Courses)

      The learning objectives for this Refresher Course are:
      • To review current initiatives and identify global challenges in improving;
      • To provide an understanding about the different methods for calculating needs;
      • To explain and facilitate the available tools for the calculation of radiotherapy resources and the costs associated;
      • To discuss strategies in developing investment cases for radiotherapy;
      • To understand the meaning of Valued-based healthcare in radiotherapy.

      • 12:30
        Global efforts 20m
        Speaker: Mary Gospodarowicz (University of Toronto, Canada)
      • 12:50
        Challenges 20m
        Speaker: Surbhi Grover (Hospital of the University of Pennsylvania, USA)
      • 13:10
        Translating incidence into needs 20m
        Speaker: Michael Barton (University of New South Wales, Australia)
      • 13:30
        Sustainability and access 20m
        Speaker: Alfredo Polo (IAEA)
      • 13:50
        Resources and costs 20m
        Speaker: Eduardo Zubizarreta (Section Head ARBR - NAHU - IAEA)
      • 14:10
        Investment framework 20m
        Speaker: Danielle Rodin ( University of Toronto, Canada)
    • 12:30 14:30
      Paediatric Radiotherapy: Parallel Sessions: Refresher Courses

      The learning objectives of this Refresher Course are:
      • To highlight the benefits and opportunities of global partnerships
      • To refresh the processes for multidisciplinary management of children with cancer including treatment of late effects and follow up into adulthood
      • To refresh contouring skills in common challenging sites in paediatric radiation therapy
      • To review current training in paediatric radiotherapy and identify innovative ideas in diverse global settings

      • 12:30
        Global Partnerships including St Jude’s activities and the GICC workshops 15m
        Speaker: Paola Friedrich (St. Jude Children's Research Hospital, USA )
      • 12:45
        Delivering Paediatric Radiotherapy within Multidisciplinary team care 15m
        Speaker: Karen Marcus (Harvard Medical School, USA )
      • 13:00
        CNS 25m
        Speaker: Sahaja Acharya (St Jude Children's Research Hospital, USA )
      • 13:25
        Non-CNS 25m
        Speaker: Susan Hiniker (Stanford University Medical Center, USA )
      • 13:50
        Management of late effects and follow up of the child into adulthood 15m
        Speaker: Stephanie Perkins (Washington University School of Medicine in St. Louis, USA )
      • 14:05
        Panel Discussion 20m

        "What training in Paediatric Radiotherapy is delivered in your country for:
        • Radiation Oncology residents
        • Radiation Oncologists taking a substantive role in Paediatric Radiotherapy"

        Speakers: Kirsten Hopkins (IAEA) , Mohammed Zaghloul (Cairo University, Egypt) , Rosangela Villar (Centro Infantil Boldrini) , Verity Ahern (University of Sydney, Australia) , Wondemagegnhu Tigeneh (Addis Ababa University, Ethiopia)
      • 14:25
        Break 5m
    • 12:30 14:30
      Planning Quality Radiotherapy Services: A City Approach: (Parallel Sessions: Side Events)

      The learning objectives for this Refresher Course are:
      i) to identify key methodological elements to estimate the demand of radiotherapy services within a defined catchment area (city), and
      ii) to become familiar with key success factors and strategies when designing city-wide approaches.

      • 12:30
        C/Can model: Planning quality radiotherapy services 15m
        Speaker: Mr Diogo Neves (City Cancer Challenge Foundation)
      • 12:45
        Demand and supply analysis: a city framework 15m
        Speaker: Rodolfo Alfonso-Laguardia (High Institute for Applied Technologies and Sciences (InSTEC), Havana, Cuba)
      • 13:00
        Building a successful public-private partnership in the health sector: key elements 15m
        Speaker: Dhawal Jhamb (Senior Investment Officer, PPP Transaction Advisory Services, IFC)
      • 13:15
        A Practical Example: Yangon, Myanmar 15m
        Speakers: Khin Cho Win (President, Myanmar Society for Radiation Oncology) , Thet Ko Aung (Technical Assistance Officer, C/Can)
      • 13:30
        Break 1h
    • 12:30 14:30
      Radiobiology: (Parallel Sessions: Refresher Courses)

      The learning objectives for this Refresher Course are:
      • To learn the basic and advanced concepts of radiobiology
      • To review advances in translational radiation biology and their applications in radiation oncology
      • To understand what the main methods and implications of radiation biology to radiation medicine are

      • 12:30
        Radiobiology of High Dose per Fraction 30m
        Speaker: Mike Joiner (Wayne State University School of Medicine, MI, USA)
      • 13:00
        Radiobiology of FLASH Therapy 25m
        Speaker: Jolyon Hendry (The University of Manchester, UK)
      • 13:25
        Personalized Radiotherapy 25m
        Speaker: Loredana Marcu (University of Oradeaa, Romania)
      • 13:50
        Radiobiological advances in Radiation Medicine 25m
        Speaker: Marjan Boerma
      • 14:15
        Break 15m
    • 14:30 15:30
      e-Contouring Workshop: e-Contouring Workshop (ESTRO)

      Learning objective(s):
      Describe clinical and anatomical rationale for target volume and organs at risk delineation
      Discuss common pitfalls in delineation
      Demonstrate accurate delineation of target volumes and organs at risk

      • 14:30
        e-contouring Workshop: CNS 1h
        Speaker: Sarah Jefferies
    • 08:20 10:05
      Advanced Technologies and Techniques in Radiation Oncology
      Conveners: Mr Daniel Berger (IAEA) , Mr Mauro Carrara
      • 08:30
        Prescribing,Recording and Reporting Proton and Light Ion Beam Therapy (ICRU 78 and 93) 20m
        Speaker: Mr Oliver Jaekel (ICRU)
      • 08:50
        Out of Field Doses 20m
        Speaker: Geoffrey Ibbott (UT MD Anderson Cancer Center)
      • 09:10
        Spatially fractionated radiation therapy: from photons to charged particles 10m
        Speaker: Mrs Yolanda Prezado (EFOMP)
      • 09:20
        kV Therapy Dosimetry Updates and Challenges 10m
        Speaker: Robin Hill (Chris O'Brien Lifehouse)
      • 09:30
        Radiation Planning Assistant: Automated contouring and treatment planning 10m
        Speaker: Mr Laurence Edward Court
      • 09:40
        The UNSCEAR 2020 report on medical exposure: approach, trends and challenges in the field of radiation therapy 20m
        Speakers: Dr Ferid Shannoun (United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)) , Dr Peter Thomas (Australian Radiation Protection and Nuclear Safety Agency, AUSTRALIA)
    • 10:05 11:25
      Physics Papers 1
      • 10:05
        Characterization of helical tomotherapy plans complexity 10m

        Introduction
        Complexity analysis has proven to be an important tool for treatment plans characterization and comparison, contributing to improve the quality, efficiency and safety of the planning and delivery processes [1]. The purpose of this work is to evaluate the complexity of helical tomotherapy (HT) plans using some indicators recently proposed [2] and assess their potential to predict the plan deliverability.

        Methodology
        100 head and neck HT clinical treatment plans generated with simultaneously integrated boost for two and three dose levels were retrospectively analysed. The prescribed dose per fraction to the high-risk planning target volume was either 2 or 2.12 Gy. All plans were created in the Tomotherapy treatment planning system v.5.1.1.6 and delivered by a Tomotherapy HD unit (Accuray Inc., Sunnyvale, CA, USA). For each plan, six complexity indicators have been calculated from the planned sinogram saved in the corresponding DICOM RT file, using a home-made MATLAB program (Mathworks, Natick, MA, USA). The computed parameters and indices included: the modulation factor (MF), the percentage of leaves with an opening time below 100 ms (%LOT < 100 ms), the percentage of leaves with an opening time close to the projection duration (%LOT > pT-20 ms), leaf open time variability (LOTV), plan sinogram time variability (PSTV) and modulation index (MI) recently adapted for HT [2].
        To assess the plans deliverability, pre-treatment quality assurance (QA) verifications were performed. Plans were recalculated in the Tomotherapy phantom (Cheese phantom) and delivered in the HT unit with the couch out of the bore. Dosimetry Check software v.5.5 (LifeLine Software Inc., Austin, TX, USA) was used to reconstruct the measured dose distribution from the acquired sinogram. The agreement between the planned and reconstructed dose, was evaluated using 3D global gamma analysis. The passing rate acceptance limit was 95% for a 3%/3 mm and 10% dose threshold (TH) criterion. In this work, more stringent criteria were also adopted, namely 3%/2 mm 10% TH, 2%/2 mm 10% TH and 2%/1 mm 10% TH.
        The correlation between the complexity metrics and the pre-treatment verification results was investigated using Spearman’s rank correlation coefficients rs. The identified dependencies were classified as: |rs| < 0.4 “weak”, 0.4 ≤ |rs| < 0.6 “moderate” and |rs| ≥ 0.6 “strong”, for a significance level of 5%.

        Results
        The average values of the complexity indicators and corresponding standard deviation for the head and neck HT plans were: MF 2.096 ± 0.175, %LOT< 100 ms 27.792 ± 3.571, %LOT > pT-20 ms 8.658 ± 3.746, LOTV 0.931 ± 0.010, PSTV 5.406 ± 0.729 and MI 10.726 ± 0.895.
        All plans were considered clinically deliverable, with an average passing rate of 98.6 ± 1.0 % (3%/3 mm, 10% TH) for the entire group. The use of more stringent criteria for gamma analysis, resulted in a wider spread in the obtained passing rates, as expected.
        Only weak associations have been identified between the complexity indicators and the verification results, regardless the adopted criteria, as can be seen in Table 1.

        The lack of correlations may be explained by the homogeneity of the considered set of plans, which led to a limited variation of both the complexity indicators and the deliverability results.

        Conclusion
        Despite the reported lack of correlations, the complexity indicators values can be taken as reference in our clinic to evaluate future plans, given that the pre-treatment QA results of the entire set included in this study were all clinically acceptable. Treatment plans with a complexity out of these limits for any of the computed metrics should be further evaluated and eventually be subjected to a more rigorous QA.

        References
        [1] Santos T, Ventura T, Lopes MC. Evaluation of the complexity of treatment plans from a national IMRT/VMAT audit – Towards a plan complexity score. Phys Med. 2020; 70:75-84; doi:10.1016/j.ejmp.2020.01.015
        [2] Santos T, Ventura T, Mateus J, Capela M, Lopes MC. On the complexity of helical tomotherapy treatment plans. J Appl Clin Med Phys. 2020; doi:10.1002/acm2.12895

        Speaker: Ms Tania Santos (University of Coimbra | IPOCFG,E.P.E.)
      • 10:15
        Clinical implementation of the MRLinac in Odense, Denmark 10m

        MRLinacs provide the means of high resolution soft-tissue image contrast at the time of treatment to visualize the target and the surrounding normal tissue for image guided radiotherapy (RT).
        The MRLinac is currently used for adaptation of the treatment based on the daily anatomical changes. This may lead to smaller margins and increased use of hypofractionation. The potential is to adapt the treatment not only based on anatomical changes but also biological response, e.g. observed from Diffusion-Weighted Imaging (DWI).
        At Odense University Hospital (OUH), the MRLinac, UNITY, Elekta, was installed during 2018. The implementation of the MRLinac was performed in close collaboration with an international group of institutions, all having the UNITY system installed.
        The local implementation is based on a multidisciplinary team of clinicians, physicists, and RTTs. All had experience in conventional RT in a department, where both CT and MR are used for RT planning. Most treatments are performed using VMAT and daily Cone Beam CT verification. All patients treated at the MRLinac are treated within clinical protocols focusing on treatment outcome and side-effects.
        The MRLinac workflow differs from conventional RT, as it offers the opportunity of daily adaptation of the treatment. The workflow comprises of a pre-treatment workflow and an online workflow. During pre-treatment, a CT and an MR scan are acquired. All contouring is based on the MR scan, while the electron density information is linked from the CT to the MR scan using deformable image registration. In addition to the standard target and organ at risk (OAR) volumes used for the treatment optimization, a set of MR-Linac specific volumes are auto-generated:
        • DelineationVolume: the volume close to the target, where OAR re-delineation is required on the daily MR scan to include the anatomical changes during the online plan adaptation.
        • ActionVolume: the volume which determines if second adaptation is required.
        • TrackingVolume: the volume that the CTV should stay within during irradiation.
        A reference treatment plan is optimised in the treatment planning system, Monaco, based on the planning MR scan. This plan is independently checked and verified using the ArcCheck phantom. The reference-treatment plan is never used, it only serves as a starting point for the optimisation of the online created adaptive treatment plans.
        The Online workflow is used after the patient is set-up in the MRLinac including the MR-coil positioning. A 3D MR is acquired, which is automatically fused to the planning MR scan. Based on the daily anatomy of the patient, the target structures from the initial pre-treatment planning scan may be shifted and rotated or possibly re-delineated while the OAR structure may require daily adjustment within the DelineationVolume. Based on the adapted contours, a new plan and dose distribution is optimised, and this new treatment plan is checked independently prior to delivery. While the delineation and re-planning are being performed, a DWI image sequence is acquired in the background for research purposes. Immediate prior to treatment, a fast 3D MR validation scan is acquired to evaluate whether the patient’s anatomy has changed during re-delineation and re-planning. If part of the target is outside the ActionVolume, the treatment beams are repositioned, and a fast re-calculation of the delivered dose is performed. Finally, during patient irradiation, a 2D MR scan is run in cine mode to validate the target position within the TrackingVolume. At the very last part of the treatment delivery, an additional fast 3D MR scan is acquired for evaluation purposes.
        The total treatment time from the patient is entering the room to the patient is leaving the treatment room is in the range of 21-60 min.
        Treatments on the MRLinac at OUH were initially only related to the pelvic region. However, currently, patients with abdominal cancers are also treated at the Unity system. Until 1st of July 2020 129 patients have been treated on the Unity system – most of the treatments are based on either a hypofractionation or SBRT scheme. Figure 1 shows the different sites treated and related fractionations; only prostate cancer patients are treated with 20 fractions.
        Implementing the MRLinac in a clinical setting requires education of a multidisciplinary team. The institutions of the MRLinacs are accumulating clinical data in a joint registration protocol, that may form the basis for selecting future patients for MRLinac treatment based on the possible gains relative to standard linac treatment. The MRLinac gives the RT community a new opportunity to “see what is being treated while treating”. This can be used to evaluate, not only what is treated on the MRLinacs, but the knowledge can feed into margins and patterns of known anatomical movements during RT. The DWI research could provide biological response information, such that the treatments can be adapted based on the likely tumor and toxicity outcome of the individual patient.

        Speaker: Dr Vibeke Nordmark Hansen (Laboratory of Radiation Physics, Odense University Hospital)
      • 10:25
        A novel quantitative metrics for assessing IMRT plan complexity: A virtual phantom study 10m

        Introduction: In IMRT treatment planning, there has been little interest in defining parameters to assess the quality of the treatment plan using quantitative metrics. This work was carried out for the first time to develop a series of virtual phantom to assess the IMRT planning complexity. Methods: A series of virtual phantoms were designed by using MATLAB® software (MathWorks, Natick, MA, United States), simulating a cylindrical-shaped planning target volume (PTV) surrounded by two cylindrical-shaped organ-at-risk (OARs). The separation of PTV-OARs was designed to have variable distances. Three different IMRT techniques were investigated: step-and-shoot IMRT (SSIMRT), volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT). Later, there were two complexity metrics being established to quantify the complexity of an IMRT treatment plan. The first was the wiggliness of dose profile for treatment plan. This was chosen as an approach to represent the complexity of a treatment plan and it was quantified as spatial complexity matrix (SCM). Both the dose profile and 3-D surface plot for 120 IMRT plans were plotted and analysed by using MATLAB® software. The second, the metric of spatial frequency ratio (SFR) was established. The proportion of rapidly varying dose with distance in a treatment plan was used to predict the complexity of a plan. The 1-D power spectral density (1D PSD) for the dose surface was generated to characterise the high and low frequency components of the dose surface. Results: For SCM analysis, the dose profiles and 3-D plots for 7-field SSIMRT plans presented a noticeable seven dose peak with higher value of maximum dose compared with VMAT and HT. The planning complexity in SSIMRT was decisive in the outcome of comparison against VMAT and HT. The calculated SCM value for SSIMRT is found to be higher than VMAT and HT. For SFR analysis, HT was having the highest SFR, followed by VMAT and SSIMRT. The higher SFR indicated that the high frequency dose was varying rapidly with the distance. This was then considered a good surrogate to represent the level of complexity for a treatment plan. Conclusion: This study has demonstrated the complexity assessments on all the IMRT plans generated using the virtual phantoms. The 3-D surface plots and 1D PSD plots generated in this study clearly presented a landscape view of the dose surface roughness and the spatial variation of high frequency dose component. The results of these studies have shown for the first time, the feasibility of using the self-developed metrics of SCM and SFR on virtual phantoms for assessing plan complexity.

        Speaker: Hwee Shin Soh (Ministry of Health Malaysia)
      • 10:35
        Effect of detector choice for commissioning measurements propagated trough beam modelling to final dose calculation 10m

        Introduction of the study
        Different small field detectors are available for commissioning measurements. For each task, i.e. depth dose curves, profiles and output factor measurements, the detector response depends on properties such as the active volume size, material composition and density relative to water. In the absence of an ideal detector, measurements are typically a compromise between detectors available and the need to address different measurement tasks correctly.
        In the treatment planning system, a beam model is fitted to match the measured data. Beam characteristics, such as the photon energy spectrum, the focal spot size and electron contamination, are tuned to reproduce dose distributions that follow the measured data. The goal of this work was to investigate how changes in the measured data affect the final dose computation.
        Methodology
        The clinical beam model of a 6 MV Elekta Versa HD accelerator was copied in the Philips Pinnacle treatment planning system and eight alternative models were created, each differing from the initial reference model in one aspect. One model parameter was altered, such that the newly modelled curve deviated by an amount typical for choosing a non-ideal but reasonable detector, for example small ionization chambers of different sizes for profiles or different diodes for output factor measurements and depth dose curves. Detector response differences were taken from measurements and from literature data.
        Three clinical VMAT plans per category head and neck, prostate, vertebrae, three breast step-and-shoot IMRT, three 3D-conformal breast tangent plans and three cranial stereotactic treatments were recalculated using the alternative models. Representative dose parameters for target volumes or organs at risk (OAR) were evaluated.
        Additionally, all plans were measured using the Sun Nuclear ArcCHECK cylinder phantom including a central dose measurement using a 0.125 ccm ionization chamber. Measurements were compared with the calculated dose distributions of the original and alternative models using gamma analysis.
        Results
        Many of the implemented changes only led to minute changes in the dose calculation for DVH parameters representing the target volume prescriptions (often < 0.3 %). The magnitude of the observed deviations depended on the body region and technique. Modifications of the depth dose distribution became apparent for targets at large depths (prostate plans) and with vertebrae plans due to dense bone material (changes approximately 1-2 %). Changes in the build-up region were generally not observable, even with surface-near target volumes (breast, head and neck). Changes in output factor tables influenced small stereotactic fields (up to around 6% change) and to a much smaller degree some of the VMATs (approximately 0.5% change). Modified penumbra did not affect the 3D-conformal breast plans, but introduced dose changes in most other plans, exceeding 1% in four of the VMAT plans. Especially dose to spared OAR, adjacent to the target volume, differed for this modification. Stereotactic treatments changed the most (3%-6% prescription dose changes).
        Results of the gamma analysis on the phantom differing from the body geometry did not always coincide with the changes in DVH. Modifications of the depth dose curve led to dose changes most apparent in prostate plans, but notably reduced gamma passing rates only for the 3D-conformal breast and the stereotactic plans. Changes of the electron contamination in the surface-near region are not accessible for the detector array measuring at approximately 3 cm depth. Substantial reductions of the gamma passing rate for most treatment techniques were only observed for the modified penumbra, with the largest changes for the stereotactic treatment and hardly any changes for the prostate and head and neck plans.
        The predicted central dose obtained with the ionization chamber changed by 1-2% for all plans for the depth dose modification and approximately 10% for the penumbra cases when the position of the ionization chamber corresponds to an organ at risk adjacent to the target volume.
        Conclusions
        In practice, choosing a non-optimal detector and consequently creating small errors of the beam model affects only dose calculations under certain conditions. However lacking correlation between dose calculation errors and quality assurance metrics, poor modelling may go unnoticed. Critical modelling parameters for most plans are the penumbra, the depth dose curve for deep targets and output factors especially for small targets. It seems necessary to validate a new beam model not only in one phantom geometry and not only with typical clinical plans (head and neck, prostate), but with dedicated or challenging plans to encompass typical errors (complex VMAT, 3D-conformal, small fields) independent of the treatment scope of the linac.

        Speaker: Sonja Wegener (University of Wuerzburg, Radiation Oncology)
      • 10:45
        FRICKE DOSIMETRY FOR BLOOD IRRADIATORS 10m

        Irradiation of blood and blood components is practiced with the main purpose of preventing graft versus host disease in immunodeficient patients. Transfusion-associated graft-versus-host disease (TA-GVHD) is a possible transfusion reaction and can often be a fatal complication occurring in patients receiving cellular blood components. Inactivation of transfused lymphocytes by the use of ionizing irradiation of blood components remains the most efficient method for inhibiting lymphocyte blast transformation and mitotic activity, hence preventing TA-GVHD. Chemical dosimetry using a standard FeSO4 solution, Fricke solution, has shown potential in being a reliable standard of absorbed dose for blood irradiation and other applications. The linearity for this dosimeter and reproducibility tests have been investigated by this group. Thus, considering all these issues, we propose the use of a Fricke dosimeter to perform blood irradiation dosimetry, for this we have provided the dose distribution in the irradiator container.
        The use of an equivalent water phantom and the control of organic and inorganic impurities in the Fricke solution are important factors to ensure that less correction is necessary for the measurements of radiation dose inside the blood irradiator. For this purpose, a specific phantom was constructed and patented by the Radiological Sciences Laboratory to perform the measurements. The phantom created by the authors consists of a cylindrical container made in a 3D printer using acrylonitrile butadiene styrene (ABS) with a density (ρ = 1.03 g.cm-3) close to that of water. It has a design suitable for the Fricke solution to be placed in small polyethylene bags of approximately 4 x 4 x 0.2 cm3. The phantom has 19 cavities with dimensions of 4 x 4 x 0.4 cm3, to accommodate the polyethylene bags filled with Fricke solution, that are spatially homogeneous distributed throughout the cylindrical volume.
        All measurements were performed under normal irradiation conditions for blood bags, including rotation of the canister and a current time for irradiation. Five bags were used as the control solution and submitted to the same conditions but were not irradiated. The absorbance was read using a Varian Cary 50 Bio spectrophotometer for the control and the irradiated solutions maintained at a temperature of 25 °C. All measurements were performed in a Gammacell 3000 Elan (Best Theratronics) blood irradiator located at the Hemocenter in Rio de Janeiro, Brazil, which uses two 137Cs sources for irradiation. The measurements were performed as a routine irradiation procedure, of 5 minutes and 49 seconds, with an expected dose of 25.7 ± 1.5 Gy in the centre of the cylinder.
        The cavities of the phantom can be grouped into three regions: the center, the top and the bottom. Five sets of measurements using 19 bags each were performed. The mean doses were calculated and were as follows: 29.28 Gy with a type A uncertainty of 1.06% for the bottom part, 30.40 Gy with a type A uncertainty of 1.10% for the central part, and 26.39 Gy with a type A uncertainty of 1.15% for the top part. The upper doses were lower than the bottom doses, and the center of the canister received the highest dose. Type A uncertainties were calculated as the standard deviation of the absorbed dose to water obtained for each group of bags, bottom, central and top, separately. Figure 1 shows the mean values for all measurements for each individual cavity. It is important to note that the nonuniformity of the source causes this high standard deviation. The increasing tendency shown in Figure 1 is due to the position within the cylinder. The dose is higher in the external part of the cylinder (C) due to its proximity to the source.

        Fig 1. Average doses and standard deviation for all 19 cavities. The dashed dotted line indicates the expected dose (25.7 Gy) and the short dashed line indicates the standard deviation of average doses.

        Fricke dosimetry provided a volumetric dose distribution evaluation with a final uncertainty of 2.07% (k=1). The obtained results showed that the setup, the Fricke dosimeter and the phantom, is able to perform dosimetry for blood irradiators. Using the Fricke system reduces the uncertainty of the dose in the centre of the mid plane of the canister by about a factor of 4 compared to that achievable using EBT film. The mean value of Fricke solution resulted in 28.7 Gy, which is about 12% greater than the expected value of 25.7 Gy, but this is not statistically significant since the 2 sigma uncertainty using EBT film is about 12%.
        We intend to implement a standard for absorbed dose to water based on Fricke chemical dosimetry and supply the need for hemocenters, hospitals and clinics to perform annual dosimetry for the irradiation of blood components as required by the Brazilian Health Regulatory Agency (ANVISA), American Association of Blood Bank (AABB) and the Brazilian National Commission of Nuclear Energy (CNEN).

        Speaker: Prof. Carla L. Mota
      • 10:55
        Development of Contact Lens-Type Ocular In Vivo Dosimeter For Accurate Evaluation Of Radiation Dose To Lens 10m

        Introduction: This study aimed to develop a contact lens-type ocular in vivo dosimeter that can be worn directly on the eye and assess its dosimetric characteristics and biological stability for radiation therapy.
        Methods: The molder of a soft contact lens was directly used to create the dosimeter, which included a radiation-sensitive component to measure the delivered dose. A flatbed scanner with a reflection mode was used to measure the change in optical density due to irradiation. The sensitivity, energy, dose rate, and angular dependence were tested, and the uncertainty in determining the dose was calculated using error propagation analysis. Sequential biological stability tests, specifically, cytotoxicity and ocular irritation tests, were conducted to ensure the safe application of the CLOD to patients.
        Results: The dosimeter demonstrated high sensitivity in the low dose region, and the sensitivity linearly decreased with the dose. A strong dose rate dependence was not obtained for the CLOD. Angular dependence was observed from 90° to 180° with a difference in response from 1% to 2%. The total uncertainty in error propagation analysis decreased as a function of the dose in the red channel. Quantitative evaluation using the MTT assay presented no cytotoxicity. Further, no corneal opacity, iris reaction, or conjunctival inflammation was observed.
        Conclusions: The CLOD is the first dosimeter that can be worn close to the eye. The results of cytotoxicity and irritation tests indicate that it is a stable medical device.

        Speaker: Hong-Gyun WU (Seoul National University Hospital)
      • 11:05
        Accuracy of an Eclipse treatment planning system for SRS 10m

        Introduction: The Royal Hospital in Muscat, Oman, obtained a Varian TrueBeam ver 2.5 SRT linac in 2016. 6 MV and 6 FFF photon beams were commissioned on an Eclipse treatment planning system (Ver 13.7) using dosimetric data ranging from 40x40 cm2 to 4x4 cm2 as recommended by the vendor. Although a dedicated iPlan treatment planning system is routinely used for stereotactic radio-surgery (SRS) planning, we wanted to investigate the feasibility of using Eclipse treatment planning system in dosimetry of treatment fields typically used in SRS treatments with dimensions smaller than those recommended by the vendor.

        Materials and methods: PDDs, OARs and output factors were measured for 6 MV and 6 FFF photon beams using a pinpoint chamber for 3x3, 2x2 and 1x1 cm2 fields. Separate beams were configured in the planning system with one being configured with beam data containing the vendor recommended dosimetric data ( fields between 40x40 and 4x4) and the other with dosimetric data for the small fields in addition to vendors recommended dosimetric data. To test the performance of the Eclipse treatment planning system we first compared PDDs of 3x3, 2x2 and 1x1 cm2 field sizes to measurements. In addition, VMAT plans for single and multiple SRS type lesions were optimized and calculated. The optimized plans were then recalculated in a standard 30x30x15 cm3 QA Solid Water phantom. Using a small thimble ionization chamber, measured and calculated doses within the QA phantom were compared.

        Results:
        Measured PDDs for 6 MV and 6FFF beams were compared to Eclipse calculated PDDs for beam configured with small fields dosimetric data. The calculated PDDs for depths 5 and 10 cm and 3x3 cm2 field size were less than 0.2% from measurements,however, for the 2x2 cm2 field size the discrepancy increased to 2.0%.
        Moreover, plans optimized and calculated with 6 MV beam configured with small field dosimetric data, the calculated and measured doses in the QA phantom were in closer agreement with one another in comparison to plans optimized with 6 MV beam configured without including small fields dosimetric data. We also noticed that the agreement between calculated and measured doses improved when jaw-tracking is disabled in plan optimization.

        Conclusion: It is important to include dosimetric data for small fields in treatment planning beam data when planning to treat small lesions. To further reduce discrepancies between calculation and measurements, we recommend using fixed-jaws positions when optimizing plans for small lesions.

        Speaker: Ms Iqbal AL AMRI (Royal hospital)
      • 11:15
        Retrospective evaluation of portal dosimetry pre-treatment quality assurance for volumetric-modulated arc therapy (VMAT) and stereotactic radiotherapy (SRT) plans 10m

        Introduction of the study
        Electronic portal imaging device (EPID) offers high-resolution digital image that can be used to quantitatively compare a measured and calculated dose distribution that is routinely used for quality assurance (QA) of volumetric-modulated arc therapy (VMAT) and stereotactic radiation therapy (SRT) treatment plans by the evaluation of the gamma index. The aim of this investigation was to evaluate the gamma passing rate (%GP), maximum gamma (γmax), average gamma (γave), maximum dose difference (DDmax) and the average dose difference (DDave) for various regions of interest using Varian’s portal dose prediction (PDP) algorithm.

        Methodolgy
        For this study, SRT and VMAT plans which were already used for patient treatment were retrospectively selected. A total of 310 treatment plans were analyzed in this study (252 VMAT plans and 73 SRT plans). The treatment sites were various, which were brain, head and neck (H&N), prostate and cervix. For VMAT and SRT treatment delivery, ton a Varian iX23 with millenium 120 MLC , Brainlab ExacTrac positioning system and 6D Robotics couche was used.

        Results:
        Our data show that the %GP, γmax and γave depend on the gamma calculation method and the acceptance criteria. Higher %GP values were obtained compared with both our current institutional action level and the American Association of Physicists in Medicine Task Group 119 recommendations.

        Conclusions:
        The results of this study can be used to establish stricter action levels for pre-treatment QA of SRT and VMAT plans. A stricter 3%/3 mm improved gamma criterion with a passing rate of 97% or the 2%/2 mm improved gamma criterion with a passing rate of 95% can be achieved without additional measurements or configurations.

        Speaker: Abdelkader Toutaoui (Hôpital Chahids Mahmoudi, Tizi Ouzou)
    • 11:25 12:00
      Poster Viewing 35m
    • 12:00 14:00
      Medical Physics Education
      Convener: Debbie Van Der Merwe
      • 12:00
        IAEA Education and Training Initiatives 20m
        Speaker: Giorgia Loreti (IAEA)
      • 12:20
        IOMP activities in medical physics education and training 20m
        Speaker: Geoffrey Ibbott (UT MD Anderson Cancer Center)
      • 12:40
        EFOMP activities in education and training of medical physicists in Europe 20m
        Speaker: Mr Brendan McClean (EFOMP)
      • 13:00
        Global Access to Medical Physics: Challenges and Opportunities (Round Table Discussion) 1h
        • Virtual mentoring in global medical physics education and training 10m
          Speaker: Mr Jacob Van Dyk
        • Challenges in establishing a clinical training programme for MP 10m
          Speaker: Mrs Graciela VELEZ (IAEA)
        • The “Open Syllabus” project – improving global access to radiation oncology medical physics residency training content 10m
          Speaker: Mr Parminder S. Basran ( MPWB)
        • Experience as a remote supervisor under the IAEA Doctoral CRP Programme 10m
          Speaker: Mr Daniel Venencia
        • Monitoring and Evaluation of IAEA e-learning Courses in Medical Physics 10m
          Speaker: Giorgia Loreti (IAEA)
    • 14:00 14:50
      Physics Papers 2
      • 14:00
        Volumetric Modulated Arc Therapy (VMAT): The gold standard for the present and future of radiotherapy? 10m

        Introduction:
        External beam radiotherapy has advanced from two-dimensional planning to intensity modulated and arc therapies. Clinical use of advanced photon therapy is increasing significantly with intensity modulated radiotherapy (IMRT) use rates constant over three decades.

        An Australian and New Zealand survey recorded 46% facilities utilize both IMRT and VMAT and 27% facilities use IMRT only. Additional publications record a decline in 3DCRT usage (67.5 % to 4.3%) and increased VMAT usage (0% to 54.8%) between 2009 and 2017 for non-small cell lung cancer (NSCLC). This trend has been observed in several other treatment sites.

        Previously two review papers were published on the clinical use of VMAT and its outcomes, assessing VMAT at the start of its implementation (2000-2010) and looking at the clinical outcomes of its implementation (2009-2016). Both found that although the use of VMAT was increasing, based on planning and feasibility studies, clinical outcome studies were scarce and report only acute toxicities. Little data on long term clinical outcomes of VMAT were cited.

        We review the current treatment techniques of six clinical sites (2017-2020), the dosimetric and clinical studies and the future role of VMAT.

        Methodology: Searches were performed through google scholar and the National Library of Medicine -PubMed using the terms “VMAT” “clinical outcomes” and “dosimetric outcomes” for the period January 2017 to present.

        Results:
        Forty-one papers were assessed involving 5,841 patients; 20 clinical outcome studies, 21 dosimetric studies; 36 analysed doses to patients; 5 assessed doses to phantoms or CT scans; 31 retrospective studies; 10 prospective studies.

        Carcinoma of prostate and cervix widely use VMAT, reporting few late toxicities and comparable acute toxicities to IMRT. VMAT utilizing hypofractionated radiotherapy schemes and simultaneous integrated boost produce reduced toxicity rates and improved tumour control for patients with prostate cancer and are beneficial for patients where brachytherapy is not feasible.

        Anorectal case studies advocate VMAT to become the gold standard, owing to anal sphincter sparing, hot spot dose reduction, better conformity and homogeneity indices, toxicity reduction and successful treatment results. Dosimetric studies have reported comparable tumour coverage between 5F-IMRT, 7F-IMRT and VMAT. However, conformity indices are better with VMAT. IMRT is only preferred for those who require intestinal protection. Significant sparing of OARs is reported for intensity modulated proton therapy (IMPT) compared to VMAT.

        3DCRT has been the gold standard for breast cancer radiotherapy. However, many centres have adopted VMAT from the outcomes of dosimetric investigations, which found superior tumour coverage with one main drawback, low-dose baths to OARs which exceed that of 3DCRT. There are several scenarios where 3DCRT is still preferred. However, new techniques like tangential VMAT meet lower OAR constraints with improved target coverage.

        Treatment of the lung has widely used VMAT techniques and flattening filter free (FFF) beams and jaw-tracking technology to reduce low-dose spillage to OARs. Wide retrospective studies revealed longer overall survival rates with IMRT and VMAT compared with 3DCRT and as such VMAT and IMRT are recommended for the management of patients with stage III NSCLC.

        Many studies for nasopharyngeal cancer (NPC) reveal IMRT and VMAT plans do not differ vastly and both techniques can meet the clinical requirements. Additionally, tumour control, survival and changes in quality of life are comparative for NPC with IMRT or VMAT.

        Although VMAT has been widely applied in clinical practice to oesophageal cases, 3DCRT remains the standard technique. Numerous planning studies demonstrated the superiority of IMRT over 3DCRT however, due to lack of clinical trials it is difficult to say if these dosimetric benefits translate into favourable clinical outcomes. One study suggests modern techniques were effective with toxicities less than grade IV however, local-regional failure was still the most common failure pattern. Dosimetric studies point to proton therapy for clinical improvement linked to dosimetric metrics.

        Prospective proton therapy studies also show clinical benefits for oropharyngeal cancer with reduced rates of PEG-tube replacement, acute hospitalization and narcotic requirements compared to VMAT. Although longer follow up is needed to determine long-term effects, initial findings show a reduction in acute toxicity and hence improved quality of life.

        Treatment of brain metastases can employ VMAT, CyberKnife (CK) or GammaKnife platforms. 6MV FFF beams can significantly improve target prescription dose conformity compared to CK. VMAT SRS has been used forsingle and multiple metastatic lesions however statistically significant low-dose spillage occur. VMAT for brain metastases reveal lower mean OARs doses, better conformities and hippocampal avoidance while maintaining target conformity and homogeneity.

        Conclusion:
        Current publications for different clinical sites suggest though 3DCRT, IMRT, VMAT and IMPT are implemented, VMAT and IMRT are most used with greater advantages of VMAT usage in most cases. Few clinical outcome studies are published with the majority reporting only acute toxicities. The need is evident for long-term, multi-centre, prospective clinical trials to fully access and accept best practices distinct to sites.

        Speaker: Mrs Sherisse Hunte (IAEA Member state- Trinidad and Tobago)
      • 14:10
        A study on the determination of relative output factors for very small fields in stereotactic radiosurgery 10m

        INTRODUCTION
        Small field dosimetry provides many challenges which are still being resolved so that radiotherapy services can have accurate radiation dosimetry. For small radiation fields, there are various physical conditions that occur including a lack of lateral charged particle equilibrium on the beam axis, the size of the detector is comparable or larger than the field size and there is partial occlusion of the primary photon source by the collimators and differences in the radiological water equivalence of the water. The IAEA TRS-483 Code of Practice (COP) provides advice on how to measure small field dosimetry data as well as correction factors for commonly used detectors for a range of field sizes and beam energies. However the COP does not include data for recently released detectors such as the IBA Razor diode and there is minimal data for very small fields with dimensions less than 5 mm. This provides a challenge for clinical radiation oncology departments which have a stereotactic radiosurgery (SRS) program using cones with beam diameters down to 4 mm as defined at the isocentre. The purpose of this work was to determine relative output factors (ROFs) for SRS cone defined fields and determine correction factors for the IBA Razor diode using the TRS-483 COP framework.

        METHODS
        All of the radiation dose measurements were performed on Varian TrueBeam STx for 6X-WFF and 6X-FFF with SRS cone sizes ranging from 4 to 17.5 mm diameter. The detectors used were the IBA Razor diode, IBA Razor ionization chambers and Gafchromic EBT3 film. The Razor diode is p-type unshielded silicon diode which was introduced by IBA as a replacement for their earlier model being the IBA SFD diode. Both of the IBA diodes are customized for measurements in small radiation fields, having an active area of 0.6 mm in diameter with a chip size of 0.95/0.4 mm (side/thickness). For comparison, the Gafchromic EBT3 film was taken as the reference dosimeter. The EBT3 film were scanned using an Epson Scanner XL11000 with 1200 dpi resolution 24 hours after exposure to radiation to allow the film to completely develop. Gafchromic EBT3 film is nearly energy-independent, has almost radiological water-equivalence, gives high spatial resolution and has been shown not to need any corrections for small field dosimetry provided a suitable methodology for the film is applied. All measurements were performed in an IBA Blue Phantom2 scanning water tank at a 5 cm depth with a source-to-surface distance of 95 cm. This geometry was selected to be consistent with the geometry of the radiotherapy treatment planning system. All ROFs were normalized to a 5 × 5 cm2 field for both 6X-WFF and 6X-FFF beams and k correction factors for the IBA Razor diode were determined using the TRS-483 COP.

        RESULTS
        A plot of the ROFs for the 6X-FFF beams is shown in figure 1 along with comparisons with other published data. There was good agreement between our measurements of the ROFs with the IBA Razor diode as compared to data provided by Cheng et al which was measured with the earlier IBA SFD. There was a maximum difference of about 1.5% for the 4 mm diameter cone. However, there are larger differences between the ROFs measured with the Razor diode in comparison to the representative data provided by Varian. The maximum difference is 4.7% for the 5 mm diameter cone and 2.6% for the 7.5 mm diameter cone for 6X-WFF and 6X-FFF beams respectively. The comparison with Peyton Irmen et al for 6X-WFF beam showed generally a good agreement most of the SRS cones sizes with less than 1% difference. However, there were differences of up to 5.8% for the smallest cone and 2.5% for the largest cone. A similar pattern was found for the 6X-FFF beam where there was a maximum difference of 5% for the smallest cone.

        CONCLUSIONS
        This work has demonstrated that the IBA Razor diode is suitable for the dosimetry of very small radiation fields as found in SRS and consistent in response to the earlier IBA SFD. There is however the need for additional work to determine suitable correction factors for this detector within the methodology of the TRS-483 COP in order to provide accurate radiation dosimetry.

        Speakers: Mr Chi Do Duc (Author) , Dr Robin Hill
      • 14:20
        Establishment of an Incident reporting and learning System as a tool for Quality Management in Uganda’s radiotherapy services: A case of the low resource setting 10m

        Introduction: The quality and safety of radiotherapy (RT) services in Sub-Saharan Africa has been a subject of major concern, as highlighted in several reports. As for Uganda, it has been delivering 2D treatments since the establishment of radiotherapy services in 1995. In 2016, the only available cobalt-60 teletherapy machine broke down. With the support of IAEA, the service was restored in 2017 with the installation of a new cobalt unit. In a bid to reduce reliance on a single machine, another cobalt unit was installed, and a linear accelerator (linac) ordered. The introduction of the linac will induce a move from 2D treatments to more advanced techniques. In order to make the move safer, it was decided to evaluate the current quality and safety of the RT treatments delivered. The main objective of this study is therefore to identify errors/incidents that happened in the last few years and develop a reporting and learning system -the first step of a broader Quality Management system.
        Methodology: To identify the errors/incidents that happened between January 2018 and December 2019, records of 731 patients out of the 3435 treated during this period of time were randomly selected and reviewed. Several parameters were checked: prescribed total and daily doses, number of fractions, normalization depths, treatment times, completeness of treatment charts, setup instructions, etc. Treatment times were recalculated and compared with the values in the treatment chart and in the record and verification system (R&V).

        Results: The errors found ranged from under-dosing (potentially leading to recurrences) to overdosing (potentially causing toxicities) of the patients, and were in different categories: dosimetry and procedures.
        Dosimetry: Dose errors were mainly due to omission of the block tray factor (43) or of the bolus (10) in the treatment time calculation, incorrect fractionation (15), and incorrect normalization depths (11).
        The comparison of the recalculated treatment times with the times used for treatment delivery to the 731 patients in 865 treatment courses, demonstrated that 84.9% of the treatments had been delivered within ±5% of the prescribed dose.
        Verification of the 1673 field sizes (FS) used for treatment, compared to the field sizes used for treatment time calculations showed a discrepancy in 11.2% of the cases. When analysed along time, a higher alteration in the field sizes was observed in 2018 with 22.4% of the cases (647), compared to 4.1% of the cases (949 in 2019.
        Procedures: Identified issues were: incomplete setup instructions (405), treatment plans not signed by RTT (478), calculations not signed by physicist (386), missing patient data in R&V (328), incomplete chart filling at the treatment stage (14).
        Waiting time from planning to start of treatment, considered as a quality index in radiotherapy, was also checked and showed a clear increasing trend: from an average of 8 days in 2018 to 21 days in 2019, with a group of 16 patients waiting for more than 100 days.
        Of the 846 total treatment courses, 44.9% were not recorded in the R&V system.

        Discussions and Conclusions:
        Some of the important differences in error occurrence along time can be explained by staff shortage or equipment problems:
        The difference in the number of field size discrepancies between 2018 and 2019 might be resulting from the fact that in 2018, planning was done by direct clinical markings due to the breakdown of the conventional simulator.
        The presence of 7 RTTs in 2018 as compared with only 2 in early 2019, could be the reason for a better compliance with procedures: a much higher number of patients’ data recorded in the R&V system, a higher agreement between chart records and the R&V system and the highest percentage of chart activities documented.
        The increase in waiting time along the years might be attributed to the conjunction of a few factors: the reduction of the number of RTTs, machine breakdowns and the introduction of a $3.2 payment per treatment fraction.
        Calculation errors by the physicists might be due to inadequate training, high workload and lack of clear setup instructions.
        Analysis of the errors show that they happen at different stages of the radiotherapy process, and that all the professional teams were involved. Improving treatment quality and safety will require changes all along the process of radiotherapy treatment: prescription, planning, calculation, treatment delivery.
        In parallel to the analysis of past treatments, we started to establish a reporting system in our department. This allowed us to identify incidents and near-misses that frequently occur in our radiotherapy practice. In order to address the problems, a series of Quality Management measures were taken: implementation of a weekly chart reviews/planning meetings and the second check of calculated treatment times.
        The last years’ incident analysis was done as the first step of a process of establishing a quality and safety management system for radiotherapy in Uganda and as a model to low-income countries.

        Speaker: Mr Ignatius Komakech (Radiotherapy Department, Uganda Cancer Institute)
      • 14:30
        Evaluation of positionning and dosimetry uncertainties in patients treated with intensity modulation radiotherapy (IMRT) for nasopharyngeal cancers in Tunisia 10m

        Purpose: The success of the IMRT treatment for nasopharyngeal patients is hampered by many sources of geometric errors and imprecision that can potentially deviate the delivered dose from the planned one, of which positioning errors are essentially noted. In fact, the radiotherapy treatment is spread over several weeks while the ballistics of the treatment are defined on a single fixed CT scan acquired during the preparation of the treatment. The reproducibility of this planned position during irradiation sessions is then of critical importance. An error in positioning or placement may be responsible for an underdosing of the target volume and/or an overdosing of the organs at risk. The aim of the work was to detect potential setup and dosimetry errors using daily kilovoltage images and EPID measurements of repeatability of the dose distribution during irradiation of IMRT patients.

        Methodology: A Varian Clinac iX, equipped with an amorphous-silicon EPID aS1000, was used in this study. We evaluated nine nasopharyngeal patients treated with IMRT. The dose prescribed was 60-70 Gy in 30-35 fractions. Immobilization of the patient was taken with masks 5 points. During the treatment, two orthogonal Kilovoltage images are obtained and compared with reference bone anatomy using automatic fusion to DRR images. The result of comparison gives the setup uncertainty in 3 directions (vertical, lateral and longitudinal). Deviations generated in the translational coordinates were analyzed and expressed in terms of mean values and their standard deviations. Additionally, portal imaging is often used for pre and during treatment anatomical setup verification. Images were collected with an EPID device for each IMRT subfield daily and compared to reference images (the first fluence treatment map) using the gamma method (DTA 3 mm, DD3%).

        Results: A total of 610 KV images and 2622 portal images were acquired over the course of the study. Setup errors were characterized by their mean values and standard deviations: -0.2±2 mm in the vertical direction, 0.6±5.2 mm in the longitudinal direction and -0.7±5.4mm in the lateral direction. For the dosimetry part, the average gamma index results were about 95.2% ± 3%. For 66% evaluated subfields, gamma index values were above 97% of analyzing fields. Only 2% of all evaluated data were with the Gamma index below 70%.

        Conclusion: The magnitude of the random, systematic and overall errors was quantified. A systematic error may be understood as an average variation occurred during the treatment. A random error on the other hand, can be defined as the dispersion of systematic errors over time of treatment. This study emphasizes the importance of daily imaging in order to reduce setup errors and daily verification of the fluence map in order to provide extra information about day-to-day repeatability of treatment.

        Speaker: Nesrine ELAMRI (University Tunis El Manar I, Medical physics unit, Radiotherapy department of Institute Salah Azaiz ,Tunis)
      • 14:40
        Determination and comparison of output factors in small field for field square and rectangular field with 5 detectors for For 6 Mv. 10m

        This is a preliminary work of the comparisons of output factor measurements for small fields in different equipment.
        Its in process the measurement with being made with EBT3 dosimetry films for the same fields. Measuring small field factors turns out to be a challenge since the ideal detector does not exist. And it is important to take this factor into account because it contributes very significantly in the calculation of delivery doses in patients. To analyze the response of each detector in relation to the square and rectangular field shape, 5 different detectors (Pinpoint 31016, Diode E 60012, Diode P 60008, Diode SRS 60018, Diamond 60019) were measured on an Elekta 6Mv accelerator. , Infinity with Agility head, 5mm multilayer, the results were compared.
        The measured fields were a total of 66 fields per camera. It was measured in the following way taking into account (table 1), the equivalent square was found, and the calculate the K-QQint for each equivalent field taking into account the field formed by the accelerator and the type of camera used by interpolating with the output corrections factor tables of TRS 483 (Table 2). The readings were performed three times at the TRS-483 small field reference conditions (Table 3).
        This study provides information on the effect of the orientation of the sheets, as well as the difference of the equivalent fields taking into account square and rectangular fields with different cameras and diodes. The measurements were made taking into account the formalism of TRS 483.
        Table (4) shows the final graph of all measurements and it is observed that for fields smaller than 2x2cm the response is very similar, however for larger fields is difference and the response of the SRS and Diamond Diodes are very similar a greater field

        Speaker: BERTHA GARCIA (RED AUNA - CLINICA DELGADO)
    • 14:50 15:30
      Poster Viewing 40m
    • 15:30 16:50
      Audits, Quality, Safety: Audits, Quality and Safety
      Conveners: Debbie Van Der Merwe, Ola Holmberg
      • 15:30
        What is New? 15m
        Speaker: Mr Andrew Nisbet
      • 15:45
        QUATRO Auditor / Update 10m
        Speaker: Mr Stefaan Vynckier
      • 15:55
        Designing a framework for improving Radiotherapy Safety and Quality in Israel 10m
        Speaker: Mrs Annette Wygoda
      • 16:05
        Enhancing quality in radiotherapy through dosimetry audits (the IROC experience) 20m
        Speaker: Mr Stephen Kry
      • 16:25
        IAEA/WHO dosimetry audits: present and future 15m
        Speaker: Pavel Kazantsev (IAEA)
      • 16:40
        Enhancing safety in radiotherapy: the IAEA Safety Standards for Medical Uses 10m
        Speaker: Ola Holmberg (IAEA)
    • 16:50 17:40
      Physics Papers 3
      • 16:50
        Dose verification from imaging to delivery during site visits in radiotherapy 10m

        Materials
        A lightweight, portable and water filled phantom was developed in STUK for radiotherapy site vis-its to verify the dose from imaging to delivery, especially for VMAT and IMRT beams, but suits for conventional beams as well. The phantom has been manufactured in STUK mechanical work-shop from PMMA and it is light to transport when empty and easy to fill and set up in hospital. Different type of detectors can be fitted in the phantom easily. Most measurements are done as point measurements with a waterproof 0.6cc chamber or Semiflex IC. Micro-ionization chamber, diamond detector or semiconductor are used seldom. If a dose distribution is needed, a piece of Gaf-Chromic radiochromic film EBT3 can be inserted in the phantom. Normally the phantom is used without any inhomogeneities, but different type of inhomogeneities can be inserted in several positions when needed. Mostly used inserts are lung and bones, but e.g. hip replacement prosthesis can also be inserted. In order to avoid artefacts and calculation errors from IC chamber, a plastic dummy IC is placed in the phantom during CT scan.

        Methods
        The phantom has been in regular use since 2014 and over 2000 photon beams has been measured during site visits. The phantom has been measured with all accelerators in Finland more than three times and has been used in some clinics abroad. The phantom has been scanned in each hospital with the local CT scanner, the same what is used for cancer patients. If there was a need for verify the image quality parameters, a CT-quality insert is added inside the phantom. This allows to verify HU values, image and contrast resolution. After analysing image parameters in CT scanner, the images are transferred to planning station and several type of treatment beams will be planned. If conventional beams are verified, usually only point dose at isocentre is calculated and measured. If VMAT or IMRT beams are verified, a CTV is drawn to detector volume and PTV and some OAR according local procedures to mimic pelvis area if no inserts are set or lung tumour region if lung insert is used.

        Results
        Most of the measured beams were in excellent agreement. The difference between calculated and measured dose has been less than 1% over half of the beams. The rest of the beams has been in good agreement to be within 3%, except for few findings with large deviation. Single cases with large dose deviation over 5% up to 12% was found during commissioning and dose error could be corrected before patient treatments.

        Conclusion
        Portable, water filled phantom with interchangeable inhomogeneities, and online measurements has been found very suitable instrument for verifying the correct dose to radiotherapy patients. If too large deviation is found, the root cause for the discrepancy can me solved at site. The measure-ments should be done first without any inhomogeneities and if agreement for the dose is within tolerances, inhomogeneities can be used.

        Speaker: Mr Petri Sipilä (STUK)
      • 17:00
        Small field absorbed dose to watwr determinations in LINC MV photon beams during site visit authority control of radiotherapy 10m

        Small field absorbed dose to water determinations in LINAC MV photon beams during site visit authority inspection of radiotherapy
        Abstract for IAEA ICARO-3 2021

        I. Jokelainen and P. Sipilä
        Radiation and Nuclear Safety Authority (STUK)

        Materials
        As a part of an authority control of radiation therapy the doses calculated by hospital dose planning systems for small static fields in LINAC photon beams were verified by absorbed dose to water measurements during the STUK site visits inspections. The absorbed doses to water were determined by ionization measurements using ionization chambers and synthetic diamond as the detectors. The calibrations of 0,6cm3 Farmer-type ionization chamber PTW30013 and the used electrometer PTW UNIDOS E are traceable to calibration laboratory SSDL-Helsinki. The small volume (0,03 cm3) Pin-Point-type ionization chamber PTW31015 and diamond detector PTW60019 (0,004 mm3) were cross calibrated during the inspections with each hospital LINAC MV photon qualities with Farmer cham-ber as a reference instrument. The measurements were made in hospitals water phantoms (50cm x 50cm x50cm).

        Methods
        During the period 2015 – 2019 a total of 1500 absorbed dose to water determinations performed as part of authority inspections of 45 linear accelerators in 13 Finnish radiotherapy centers photon radia-tion beams with different field sizes. The absorbed dose to water determinations were made in Vari-an and Elekta accelerator conventionally filtered beams (WFF: 6MV, 10MV, 15MV and 18MV) and in beams without flattening filter (FFF: 6MV and 10MV). For Farmer- and PinPoint-chamber the recombination corrections (krec) were determined for every accelerator photon qualities and the beam profile specific chamber volume averaging correction factors (kvol) were determined for every acceler-ator FFF photon qualities.
        All dose determination and dose plans were made with SSD 100 cm and in depth of 10 cm. The Pin-Poin-chamber PTW31015 and diamond detector PTW60019 were calibrated in reference geometry (SSD 100 cm, FS 10x10 cm2, depth 10 cm) for all measured photon energies of every used LINAC. Dose plans were calculated for field sizes from 30x30 cm2 to 2x2 cm2. Farmer-type chamber was used for dose determinations in fields from 5x5 cm2 to 30x30 cm2, PinPoint chamber and diamond detector in fields from 2x2 cm2 to 10x10 cm2.

        Results
        Most of the dose plans were in good agreement with doses measured by STUK to be within ±2 %.
        In one hospital the dose deviation exceeded the STUK acceptance criteria (±3 %) with field sizes 4x4 cm2, 3x3 cm2 and 2x2 cm2 in 6 MV beam and with 2x2 cm2 field size in 15 MV beam, having max. deviation of 7 % in 6 MV 2x2 cm2 field. After updating the hospital dose planning system algo-rithm and the input data the deviation decreased below 4 %. The agreement with doses measured with cross calibrated diamond detector and PinPoint chamber was within 0,5 %, except for 2x2 cm2 field size were the deviations of 1 % were found. The deviation in the calibration factors of cross calibrated diamond detector PTW60019 and ionization chamber PTW31015 in different LINAC beams having same nominal energy were within ±0,6 %.

        Conclusion
        For verifying the input data of hospital dose planning system the absorbed dose to water measure-ments during the authority site visits with field sizes bellow 10x10 cm2 has been found useful. The synthetic diamond detector having small energy dependence in LINAC MV beams has been found suitable cross calibrated detector for small field dosimetry with field sizes down to 2x2 cm2, and PinPoint ionization chamber PTW31015 down to 3x3 cm2.

        Speaker: Mr Ilkka Jokelainen (Radiation and Nuclear Safety Authority)
      • 17:10
        Introduction of the IAEA/WHO Electron Beam Dosimetry Audit Service 10m

        Introduction

        The International Atomic Energy Agency (IAEA) together with the World Health Organization (WHO) have been providing dosimetry audits for radiotherapy facilities primarily in low- and middle-income countries around the world for over 50 years. Until recently, the regular audit service was limited to checking of absorbed dose to water in high energy photon beams in reference conditions. The new electron beam audit service has been thoroughly tested prior to conducting a multi-centre pilot study and eventually launching as a routine service.

        Methodology

        The IAEA/WHO audit service employs radiophotoluminescent glass dosimeters (RPLDs) for determining absorbed dose to water. The RPL dosimeter consists of a 12 mm long and 1.5 mm diameter GD-302M glass rod encapsulated in a watertight capsule made of high-density polyethylene. Each dosimeter set consists of two RPLDs for irradiation in one beam and one RPLD used for background monitoring. During a photon beam audit, RPLDs are irradiated in the reference conditions according to TRS-398 using the standard IAEA holder (10 cm depth in water, 10×10 cm2 field, SSD or SAD geometry). Upon return to the IAEA, the dose (D) to an RPLD is calculated using the following equation:


        D = M · N · SCF · fenergy · fholder · fnon-linearity · ffading

        Where M is the counts of photoluminescence corrected for readout magazine position, N is the calibration coefficient of the RPLD system, SCF is the sensitivity correction factor for the RPLD used and f are the associated correction factors for the stated subscripts.


        The reference depth for electron beams depends on the beam energy (TRS-398), thus a special RPLD holder was developed to allow for a precise dosimeter positioning at any depth. The holder comprises of a 1 cm thick disk made of PMMA with a hollow channel in the mid-plane, which has a variable diameter, so the RPLD can be tightly positioned in the middle of the disk. The disk can be mounted either on top of a Roos or Markus chamber holder using two adapter rings of corresponding diameters in a water tank. The audit participants would be expected to perform a measurement with a calibrated chamber to determine the absorbed dose to water in the electron beam audited, replace the chamber with the RPLD holder, insert glass dosimeters and irradiate them one by one in the same conditions.

        Commissioning tests for the audit methodology were conducted at the IAEA Dosimetry Laboratory using a Varian TrueBeam linac with seven electron beams with energies ranging from 6 MeV to 22 MeV. These tests were performed to evaluate the electron beam specific energy (fenergy) and holder correction factors (fholder) for RPLDs. The energy correction factor was measured as the ratio of the RPLD responses in a 60Co beam to each of the other seven electron beam energies. The holder correction factor was determined as the ratio of a detector’s response in water without and with the holder in the same irradiation geometry. The measurements were done using an Exradin W1 plastic scintillation detector and an IBA Razor diode. The experimental setup was established in a PTW MP3 water tank with the detectors positioned at the reference depths for each electron energy using a 10 × 10 cm2 applicator, 100 cm SSD. Reference depths were determined using a Roos chamber through PDD curve measurements.

        Additional developments were performed on an organisational level to facilitate the execution of electron beam audits. These included the preparation of instructions, datasheets and database developments. Finally, several blind dose irradiations following the developed methodology were conducted to test it internally, in preparation for a multi-centre pilot study and international service roll out.

        Results

        The results of the holder and energy correction factor determination are shown in Figure 1. The holder correction factor values are based on the results of 10 measurement sessions per energy for each of the two detectors used and the type A relative standard uncertainty ur (fholder) of the factors measured is 0.1%. The energy correction factor values are based on the response of 20 RPLDs per beam energy and the associated type A ur(fenergy) is 0.5%. For the electron beam energies used, the product of the two correction factors described ranges between 1.04 and 1.05, compared to photons where it ranges from 1.01 to 1.04 in the therapeutic energy range. While holder corrections are of comparable magnitude for both modalities, energy corrections are substantially larger for electron beams and do not exhibit a linear dependence like for photon beams.

        Conclusion

        A new RPLD holder was developed and the required correction factors specific for electron audits were measured. In combination with the administrative developments described, they will enable the new service for auditing electron beams to be available in 2021, following a multi-centre pilot audit.

        Speakers: Mr Alexis DIMITRIADIS (IAEA) , Mr Pavel KAZANTSEV (IAEA)
      • 17:20
        Medical physics outsourcing in radiotherapy in France: services, practices, limits and points of vigilance 10m

        Introduction
        The practice of radiotherapy includes medical physics activities prior to patient treatments (acceptance and commissioning of medical devices), during the care of each patient (dosimetry planning) and concomitantly with clinical activity (quality control). These activities, which guarantee the quality and effectiveness of the treatment delivered to each patient, are partly or totally distinct from clinical activity, temporally and/or materially. Consequently, radiation therapy departments are exploring the possibility of outsourcing some of these activities when they can be carried out remotely - this is the case with dosimetry planning - or of delegating them to external service providers for those that require additional staff or are heavy consumers of medical physics human resources and "machine time" resources. In France, consulting medical companies and physicists, independent or employees of medical establishments, offer occasional services for the commissioning of medical devices or the deployment of new techniques, and recently, routine services linked to clinical management and individual patients. If the carrying out of certain activities remotely can make it possible to offer equity in access to care, the fact remains that the benefits / risks balance induced by these practices must be assessed. If necessary, the activity should be supervised, in particular in an area such as radiotherapy.
        In this study, the IRSN did an inventory of the practices of outsourcing in radiotherapy in France and has evaluated the limits, points of vigilance from the technical, organizational and human points of view.
        • Methodology
        This study is based on a literature review and survey analysis. One survey was sent to 16 external service providers identified as working in France. The survey was defined in order to make an inventory of the services provided in medical physics in radiotherapy currently in France and to collect information on the progress of the services, the staff involved, the risk analysis and control, the relations with the manufacturers and the responsibilities. Two other surveys are planned to be sent to customers and manufacturers.

        • Results
        In France, the services provided by the external providers are machine commissioning, clinical implementation of advanced treatments (VMAT, stereotactic treatment or other advanced techniques), radiation protection, clinical “routine” task (quality control, treatment planning), audit and consulting. No service provider declared to be concerned by the outsourcing of a long-term activity. All companies involved in "routine" activities offer treatment planning. Regarding exchanges with on-site medical physicists, half of the providers specified to interact with them before establishing a quote, unlike the others. Half of the service providers declare that they provide feedback at the end of the service. In half of the cases, the services are provided during treatment hours. An external service provider indicated that its company routinely carries out activities outside of these time slots. All the answers pointed to a responsibility transferred to the customer during the validation of the service. The two most cited positive aspects of external services are providing a strong expertise and saving time.
        From external provider’s survey, one point of vigilance is about conflict situations between hospital management and physicists: providers need a framework to be able to work properly with on-site physicists, transmit the necessary information and provide the necessary skills.
        Regarding outsourcing, some regulations exist in other domains than radiotherapy as bank and operating nuclear power plants. For example, for activities related to the core business, skills are required. Preliminary results on medical physicists interviews show two first points of vigilance: the need to frame the clinical validation of the service (the responsibility transfer to the clinical physicist appears not clear) and the need to manage services provider’s skills and specially training followed. Medical physicists and radiotherapy departments also need to have information on the quality of the service offered.
        • Conclusion
        There is no regulation for radiotherapy outsourcing in France. The provider’s practices are heterogeneous. The surveys made by the IRSN started to highlight points of vigilance that deserve to be processed with regulation or good practice guides. They concern provider’s training and skills, clinical validation but also risk management for conflict situations.

        Speaker: Magali EDOUARD (IRSN)
      • 17:30
        Following up on radiotherapy dosimetry audit discrepancies (2018-2020): the IAEA experience 10m
        Speaker: Mr Godfrey AZANGWE
    • 17:40 18:00
      Poster Viewing 20m
    • 10:00 10:30
      Radiotherapy in National Cancer Control Programmes: Keynote Lecture: Live Broadcast
      • 10:00
        Programme of Action for Cancer Therapy 30m
        Speaker: Lisa STEVENS (International Atomic Energy Agency, Department of Technical Cooperation)
    • 10:30 11:00
      IAEA Quality Assurance Team for Radiation Oncology: Keynote Lecture: Live Broadcast

      Learning Objectives: To understand the role of independent external audits are a necessary part of a comprehensive quality assurance (QA) programme in radiation oncology. A comprehensive audit of a radiotherapy programme reviews and evaluates the quality of all elements involved in radiation therapy, including staff, equipment and procedures, patient protection and safety, and overall performance of the radiotherapy department, as well as its interaction with external service providers. Possible gaps in technology, human resources and procedures will be identified so that the institutions audited will be able to document areas for improvement.

      • 10:30
        The IAEA Quality Assurance Team for Radiation Oncology 15m

        The keynote lecture will contribute to the understanding of the role of independent external audits which are a necessary part of a comprehensive quality assurance (QA) programme in radiation oncology. A comprehensive audit of a radiotherapy programme reviews and evaluates the quality of all the elements involved in radiation therapy, including staff, equipment and procedures, patient protection and safety, and, overall performance of the radiotherapy department, as well as its interaction with external service providers. Possible gaps in technology, human resources and procedures will be identified so that the institutions audited will be able to document areas for improvement.

        Speaker: Stefaan VYNCKIER (Université Catholique de Louvain)
      • 10:45
        Building National Quality Audit Programme for Radiotherapy 15m

        The keynote lecture will describe the implementation of the IAEA QUATRO at the national level, with Belgium as a model.

        Speaker: Aude VAANDERING
    • 11:00 11:30
      COVID
      • 11:00
        Strategies in Ensuring Continuity of Radiotherapy Services in the Context of COVID-19 30m
        Speaker: Matthias GUCKENBERGER (University Hospital Zurich, University of Zurich)
    • 11:30 12:00
      Proton and ion beam therapy: Proton and Ion Beam Therapy

      Learning objective(s):
      Discuss the concept and limits of proton therapy

      • 11:30
        Proton: Truths and Lies 30m
        Speaker: Damien WEBER ( Paul Scherrer Institute (PSI) Centre for Proton Therapy (CPT))
    • 12:00 12:30
      Telemedicine

      Learning objective(s):
      1. Discuss the scope of telemedicine in radiotherapy
      2. Discuss feasibility of telemedicine in the field of radiotherapy in low and middle income countries

      • 12:00
        Telemedicine in Radiation Oncology 30m

        The keynote lecture will address the following points:
        1. Discuss the scope of telemedicine in radiotherapy
        2. Discuss feasibility of telemedicine in the field of radiotherapy in low and middle income countries

        Speaker: Iain WARD (St George's Cancer Care, Christchurch, New Zealand)
    • 12:30 13:00
      60 years of the Directory of Radiotherapy Centres (DIRAC): Keynote Lecture: Live Broadcast

      Learning objective(s):
      Review the 60 years experience of DIRAC

      • 12:30
        Directory of Radiotherapy Centres (DIRAC): 60 Years and Beyond 30m

        The goal of this keynote lecture is to present an overview of the history of DIRAC, the current and planned functionalities, data quality assurance workflow; and to present a snapshot of the current situation of radiotherapy in 2020.

        Speaker: Jose Alfredo Polo Rubio (International Atomic Energy Agency, Division of Human Health)
    • 13:00 14:00
      Live session: Q&A: Ask the Experts
    • 14:00 14:30
      Closing Remarks