Dosimetry and safety of single-channel applicators for intracavitary brachytherapy in cervical cancer

Abstract

High-dose-rate intracavitary brachytherapy plays a crucial role in achieving local control in the treatment of unresectable uterine cervical cancer. In this treatment approach, the single-channel applicator (SCA) offers a simpler structure for implantation compared to the fletcher applicator set (FAS), easing the treatment planning. To evaluate the dosimetry and safety of the SCA for intracavitary brachytherapy in cervical cancer, the present study aims to assess its dose distribution in relation to the FAS. In this study, we compared the physical and dosimetric characteristics of the inferential reference points (A, cervix; B, bladder; and R, rectum) of the SCA to those obtained with tandem and FAS dosing. Dosimetric characteristics and dose distributions in a Chinese female anthropomorphic phantom were evaluated using RGD-3B thermoluminescent dosimetry. The SCA generated an oblate, pear-shaped dose distribution curve, resulting in a reduced high-dose area along the bladder-rectum axis. Compared to the tandem, the SCA resulted in dose reductions of 21% and 17% at the bladder and rectum, respectively. When compared to the FAS, the dosing with the SCA at the bladder and rectum did not show significant differences concerning the occurrence of severe toxic effects. The SCA demonstrated a dose distribution curve similar to the standard FAS but not the tandem. The results of the present study indicate that both SCA and FAS showed equally acute toxicity and resulted in late injuries to the rectum and bladder. Nevertheless, the SCA’s simpler structure, which allows for more convenient placement and planning, warrants further clinical investigations to assess its efficacy and practical application.