“EVALUATION OF CUSTOMIZED TREATMENT PLANNING FOR IMAGE-GUIDED HIGH-DOSE-RATE BRACHYTHERAPY FOR CERVICAL CANCER.” Niemann I, van Niekerk L, African Journal of Medical Physics, Volume 2 (Suppl), 2019, https://globalmedicalphysics.org/wp-content/uploads/2020/05/AJMP-2Supplement-SAAPMB.pdf
I Niemann, L van Niekerk - Netcare Hospitals Pty. Ltd
High-dose-rate (HDR) Brachytherapy has been highly adopted in recent years and it has been recommended that the use of MRI imaging is the best practice for cervical Brachytherapy treatment. This approach is not frequently used in South Africa due to the lack of MRI scanner availability therefore CT scanning is a more accessible approach. The Single Plan (SP) approach is used widely which involves contouring and treatment planning at the first fraction and then applying the same treatment plan to the remaining fractions. Customized planning (CP) is a widely implemented approach which involves contouring and treatment planning at each fraction. The purpose of this study was to investigate the various differences to Organ at Risk (OAR) doses when CP is used instead of the SP approach
Materials and Methods:
22 CT-based treatment plans were evaluated for 6 patients receiving HDR Cervical brachytherapy prescribed to point A. For each patient approximately 4 treatment fractions were planned with varying prescription sizes. For each fraction the OARs (Bladder and Rectum) was contoured. CP and SP were used for each patient. For the SP approach the first fraction CT scan was adapted for subsequent treatment fractions and dwell times were replicated.
The dose per fraction for each patient to point A and theD2cc to the OARs was obtained. The average dose per fraction during the CP approach to Point A was 6,42 Gy2, 7,42 Gy2 to the Bladder and 4,84 Gy2 to the Rectum. For the SP approach the average dose per fraction to Point A was 6,76 Gy2, 8,21 Gy2 to the Bladder and 5,66 Gy2 to the Rectum.
Conclusion: Dose values for the SP approach were generally higher than for the CP approach. In particular, a significant increase in the total dose to the Rectum (D2cc) from 23.0 to 31.2 Gy3 was observed for one patient. Variation in prescription made it difficult to obtain comparable results amongst patients. Due to lack of statistics a follow up study is required to draw a more accurate conclusion..