Sherif Reham S, Kareem Hend M, El-Gebaly Reem H, Shehata Mohamed A, Aziz Reham A A
Department of Biophysics, Faculty of Science, Cairo University, Giza, Egypt.
Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, Menoufia University, Menoufia, Egypt.
Int J Risk Saf Med. 2025 Jun 19:9246479251353380. doi: 10.1177/09246479251353380.
BackgroundImage-guided brachytherapy became essential to cervical cancer treatment following chemo-radiotherapy. A variety of applicators including Tandem-Ring (TR) and Tandem-Ovoid (TO) applicators are used to apply brachytherapy.ObjectiveThis study aims to dosimetrically compare TR versus TO applicators by using two different optimization techniques.MethodsBoth applicator sets were applied to the 24 patients. The prescribed dose was 7 Gy/fraction, and the treatment plans were normalized to HR-CTV. Two different optimization techniques are applied, along the four treatment fractions. The first optimization technique was a theoretical assumption that aimed to deliver 7 Gy to 90 % of the volume of the HR-CTV. While the second was the clinical situation which aimed to preserve the organs at risk (OARs) according to the ICRU 89 dose-volume constraints, considering that, 90% of HR-CTV is covered by not less than 90% of the prescribed dose. DVHs were generated, and dosimetric parameters including point A, and D2cc of rectum, bladder, and sigmoid, as well as the dose at different volumes of HR-CTV and IR-CTV, were recorded and compared.ResultsThe results demonstrate that using Ovoid-Tandem applicators achieved significantly higher dose at point A, significantly higher coverage to both HR-CTV and IR-CTV, in addition to significantly better protection to the mean D2cc of the rectum in both optimization techniques. On the other hand, using Ring-Tandem applicators give significantly more protection to the mean D2cc of the bladder, but HR-CTV and IR-CTV have significantly lower coverage.ConclusionOvoid-Tandem and Ring-Tandem applicators are the most common interchangeable intracavitary gynecological applicators. In this study, the results demonstrated that Ovoid-Tandem applicators have the advantages of significantly higher coverage for HR-CTV, and IR-CTV, in addition to more protection for D2cc of the rectum. On the contrary, Ring-Tandem applicators can provide higher protection for D2cc of the bladder, and more comfort to the patients.
背景
图像引导近距离放射治疗在宫颈癌放化疗后成为关键的治疗手段。包括串珠-环形（TR）和串珠-卵形（TO）施源器在内的多种施源器被用于实施近距离放射治疗。
目的
本研究旨在通过使用两种不同的优化技术，对TR和TO施源器进行剂量学比较。
方法
将两种施源器套装应用于24例患者。处方剂量为7Gy/分次，治疗计划归一化至高危临床靶区（HR-CTV）。在四个治疗分次中应用两种不同的优化技术。第一种优化技术是一个理论假设，旨在使HR-CTV体积的90%接受7Gy剂量。而第二种是临床情况，旨在根据国际辐射单位与测量委员会（ICRU）89号报告的剂量体积限制来保护危及器官（OARs），即90%的HR-CTV接受不少于90%的处方剂量。生成剂量体积直方图（DVHs），记录并比较包括A点以及直肠、膀胱和乙状结肠的D2cc等剂量学参数，以及HR-CTV和中间临床靶区（IR-CTV）不同体积处的剂量。
结果
结果表明，在两种优化技术中，使用卵形-串珠施源器在A点实现了显著更高的剂量，对HR-CTV和IR-CTV的覆盖显著更高，此外对直肠的平均D2cc有显著更好的保护。另一方面，使用环形-串珠施源器对膀胱的平均D2cc有显著更多的保护，但HR-CTV和IR-CTV的覆盖显著更低。
结论
卵形-串珠和环形-串珠施源器是最常用且可互换的腔内妇科施源器。在本研究中，结果表明卵形-串珠施源器具有对HR-CTV和IR-CTV覆盖显著更高的优势，此外对直肠的D2cc有更多保护。相反，环形-串珠施源器可为膀胱的D2cc提供更高保护，并给患者带来更多舒适感。
