High-dose-rate-intracavitary brachytherapy applications and the difference in the bladder and rectum doses: a study from rural centre of Maharashatra, India.

ABSTRACT

AIM: To report the difference in the bladder and rectum doses with different applications by the radiotherapists in the same patient of the carcinoma of the uterine cervix treated by multiple fractions of high-dose-rate (HDR) intracavitary brachytherapy (ICBT). MATERIALS AND METHODS: Between January 2003 to December 2004, a total of 60 cases of the carcinoma uterine cervix were selected randomly for the retrospective analyses. All 60 cases were grouped in six groups according to the treating radiotherapist who did the HDR-ICBT application. Three radiotherapists were considered for this study, named A, B and C. Ten cases for each radiotherapist in whom all three applications were done by the same radiotherapist. And 10 cases for each radiotherapist with shared applications in the same patient (A+B, A+C and B+C). The bladder and rectal doses were calculated in reference to point "A" dose and were limited to 80% of prescribed point "A" dose, as per ICRU-38 recommendations. Received dose grouped in three groups--less then 80% (< 80%), 80-100% and above 100% (>100%). A total of 180 applications for 60 patients were calculated for the above analyses. RESULTS: There is a lot of difference in the bladder and rectal doses with the application by the different radiotherapists, even in the same patient with multiple fractions of HDR-ICBT. Applications by 'A' radiotherapist were within the limits in the self as well as in the shared groups more number of times, by 'B' radiotherapist was more times exceeding the limit and by 'C' radiotherapist doses were in between the A and B. DISCUSSION AND CONCLUSION: For the rectal and bladder doses most important factors are patient's age, disease stage, duration between EBRT and HDR-ICRT and patient anatomy, but these differences can be minimized to some extent by careful application, proper packing and proper fixation.