Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Radiology Department, Kabul University of Medical Sciences, Kabul, Afghanistan.
Radiol Phys Technol. 2022 Dec;15(4):387-397. doi: 10.1007/s12194-022-00680-4. Epub 2022 Sep 7.
This study aimed to evaluate the dose modulation potential of static and dynamic steel-shielded applicators using the Geant4 Application for Emission Tomography (GATE) Monte Carlo code for the treatment of vaginal cancer. The GATE TOOLKIT (version 9.0) was used to simulate vaginal cancer intensity-modulated brachytherapy (IMBT) in a pelvic water-equivalent phantom. IMBT performance of a multichannel static and single-channel dynamic steel-shielded applicator was compared to that of a conventional multichannel Plexiglas applicator. DoseActors were defined to calculate the absorbed dose and attached to the voxelized target and organs at risk (OARs). Co and Ir high-dose-rate seeds were used as irradiation sources. Dynamic IMBT decreased the D of the rectum and bladder by 28.67 and 28.11% using the Co source and by 40.00 and 36.34% using the Ir source, respectively. Static IMBT decreased the D for the rectum and bladder by 11.69 and 9.29% using the Co source and by 22.21 and 17.71% using the Ir source, respectively. In contrast, absorbed dose parameters (D, D, and D) for the target in the three techniques showed a mean relative variation of 0.96% (0.00-7.49%) for both sources. Static and dynamic IMBT using steel-shielded applicators provided relatively better OAR protection while maintaining similar target coverage in the treatment of vaginal cancer.
本研究旨在评估静态和动态钢屏蔽施源器的剂量调制潜力，使用 Geant4 应用于发射断层扫描 (GATE) 蒙特卡罗代码治疗阴道癌。使用 GATE TOOLKIT（版本 9.0）模拟盆腔水等效体模中的阴道癌强度调制近距离治疗（IMBT）。比较了多通道静态和单通道动态钢屏蔽施源器与传统多通道有机玻璃施源器的 IMBT 性能。定义了 DoseActors 来计算吸收剂量，并将其附加到体素化靶区和危及器官（OARs）上。Co 和 Ir 高剂量率种子被用作照射源。使用 Co 源，动态 IMBT 使直肠和膀胱的 D 分别降低了 28.67%和 28.11%，使用 Ir 源则分别降低了 40.00%和 36.34%。使用 Co 源，静态 IMBT 使直肠和膀胱的 D 分别降低了 11.69%和 9.29%，使用 Ir 源则分别降低了 22.21%和 17.71%。相比之下，三种技术的靶区吸收剂量参数（D、D 和 D）对于两种源均显示出 0.96%（0.00-7.49%）的平均相对变化。使用钢屏蔽施源器的静态和动态 IMBT 在治疗阴道癌时提供了相对更好的 OAR 保护，同时保持了类似的靶区覆盖。
