A dosimetric correlation between the bladder filling volume and its effects on radiation dose during high-dose-rate intracavitary brachytherapy in patients with cervical cancer.

BACKGROUND

The purpose of this study was to establish a dosimetric correlation between the bladder filling volume and its effects on the dose received by the organs at risk (OARs) (bladder, rectum, sigmoid colon and small intestine) during computed tomography (CT)-guided high-dose-rate intracavitary brachytherapy (HDR-ICBT) in patients with cervical cancer and to determine the optimized bladder filling volume.

METHODOLOGY: In this retrospective study, the dosimetric parameters of 230 cervical cancer patients (stage IIa, IIb, IIIa, IIIb, IIIc, and IV) treated with external beam radiotherapy followed by CT-guided HDR-ICBT at our institute between June 2021 and September 2023 were studied.

RESULTS

The dose-volume histogram (DVH) parameters of the bladder increased with increasing volume of the bladder. The minimum dose to the bladder was observed when the bladder volume was less than 80 ml. The minimum dose to the small intestine was recorded when the bladder volume was greater than 120 ml. The correlations between the bladder volume and the doses received by the rectum and the sigmoid were not statistically significant.

CONCLUSION

There is a relationship between the bladder filling volume and the dose received by the bladder and small intestine. A bladder filling volume of approximately 80 ml or less was well tolerated and achieved a reasonably reproducible bladder volume during cervical brachytherapy, although small intestine doses are lower with greater bladder filling volumes.