Egor Titovich (N.N. Alexandrov National Cancer Centre of Belarus)
Objective: To preform dose-volume statistics comparison ofthe ultrasound and IBU-guided brachytherapy treatment plans in locally advanced cervical carcinoma using 3D CT and/or MR imaging. Material and methods: From April to September 2016, 14 patients with locally advanced cervix carcinoma were treated in N.N. Alexandrov National Cancer Centre of Belarus. All patients underwent EBRT 50Gy/25 fractions to the entire pelvis region (3D CT-based treatment planning). After that, all patients received 5Gy/fraction intracavitary brachytherapy (5 fractions in 3 weeks). All applications were performed under theultrasound control. The bladder was filled with 100 ml saline to ensure good visualization and to avoid the bulb. IU-channel for the ring applicator was selected according to the size of the uterus (obtained using ultrasound imaging). US-guided treatment planning enables visualization of the cervix and uterus and allows sparing ofthe normal tissues. This planning is aimed to cover a whole cervix volume with 100% of theprescribed dose. X-ray imaging was performed using IBU-Digital. 5Gy isodose was normalized to Manchester points A. According to GEC-ESTRO recommendations CTV High Risk (CTV HR) was identified using the CT and MRI fusedimage. The bladder, rectum and sigmoid were outlined as OARs. US and IBU-based calculated treatment plans were transferred to the 3D CT or MRI scans to define D2cc OARs and D90 CTV HR. The total accumulated dose value for EBRT and brachytherapy boost were evaluated in terms of equivalent dose in 2 Gy per fraction (EQD2), using a/b = 3 Gy for OARs and a/b = 10 Gy for CTV HR. Results: Figure 1 shows the relationships between the D90 of CTV HR and OARs. No clear relationships between D90 of CTV HR and OARs D2cc dose were observed. The OARs D2cc mean dose value in IBU-based treatment plans was higher than in US-based plans. Furthermore, themean total dose value was higher on US-based plans. Figure 1. Dose-volume statistics for the US and IBU-guided brachytherapy treatment plans Conclusion: Using ultrasound in gynaecologic brachytherapy to guide the applicator placement allows to avoid perforation and optimize the applicator position within the uterine canal, and thus to improve thequality of implants. Ultrasound-guided brachytherapy planning in locally advanced cervical carcinoma in comparison with IBU-based planning has increased target coverage and reduced overall dose to the OARs.
|Institution||N.N. Alexandrov National Cancer Centre of Belarus|
|Country||Republic of Belarus|
Dzianis Kazlouski (N.N. Alexandrov National Cancer Centre of Belarus)
Andrei Saroka (N.N. Alexandrov National Cancer Center of Belarus) Egor Titovich (N.N. Alexandrov National Cancer Centre of Belarus) Valiantsina Suslava (N.N. Alexandrov National Cancer Center of Belarus) Yuliya Kazlouskaya (N.N. Alexandrov National Cancer Center of Belarus)