A dosimetric comparison of brachytherapy sources for endometrial cancer: Iridium-192 and an electronic brachytherapy source with multichannel cylinders and a three-dimensional technique

Abstract

Abstract Background and purpose For patients with postoperative endometrial cancer (EC), Ir192 vaginal brachytherapy (IBT) was commonly used. We would devise a novel multi-channel vaginal applicator which could be equipped to an electronic brachytherapy (EBT) device. We aimed to explore the physical parameter differences between EBT and IBT. Materials and Methods This study retrospectively included 20 EC patients receiving adjuvant IBT from March 1, 2023 to May 1, 2023. The multi-channel vaginal cylinders were used and three-dimensional plans were performed. We designed a multi-channel vaginal applicator model and simulate a three-dimensional EBT plan. Results Twenty EBT plans were compared with 20 IBT plans. For mean dose of CTV, EBT was significantly higher (738.3 vs. 684.3cGy, p = 0.000). As to CTV coverage, there was no significant difference between EBT and IBT plan. For high-dose areas (V200% and V150%), EBT values were significantly higher. There were no significant differences in the maximum doses of vaginal mucosa between EBT and IBT, whether at the apex (median dose: 961.5 vs. 844.0cGy, p = 0.079) or in the middle segment. For bladder and rectum, both the low-dose area and high-dose area, values from EBT plans were significantly lower. For the conformity index, there was no significant difference between EBT and IBT plans. For the dose homogeneity index, EBT value was lower. Conclusion For patients who would use this novel multi-channel vaginal applicator and receive a three-dimensional radiotherapy plan, the target volume would get a higher dose while retaining the equivalent target coverage and organs at risk would get lower dose.