Bellezzo Murillo, Fonseca Gabriel P, Verrijssen An-Sofie, Voncken Robert, Van den Bosch Michiel R, Yoriyaz Hélio, Reniers Brigitte, Berbée Maaike, Van Limbergen Evert J, Verhaegen Frank
Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands; Centro de Engenharia Nuclear, Instituto de Pesquisas Energéticas e Nucleares IPEN-CNEN/SP, São Paulo, Brazil.
Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.
Brachytherapy. 2018 Nov-Dec;17(6):1037-1044. doi: 10.1016/j.brachy.2018.07.012. Epub 2018 Aug 16.
Dose escalation to rectal tumors leads to higher complete response rates and may thereby enable omission of surgery. Important advantages of endoluminal boosting techniques include the possibility to apply a more selective/localized boost than using external beam radiotherapy. A novel brachytherapy (BT) rectal applicator with lateral shielding was designed to be used with a rectoscope for eye-guided positioning to deliver a dose distribution similar to the one of contact x-ray radiotherapy devices, using commonly available high-dose-rate Ir BT sources.
A cylindrical multichannel BT applicator with lateral shielding was designed by Monte Carlo modeling, validated experimentally with film dosimetry and compared with results found in the literature for the Papillon 50 (P50) contact x-ray radiotherapy device regarding rectoscope dimensions, radiation beam shape, dose fall-off, and treatment time.
The multichannel applicator designed is able to deliver 30 Gy under 13 min with a 20350 U (5 Ci) source. The use of multiple channels and lateral shielding provide a uniform circular treatment surface with 22 mm in diameter. The resulting dose fall-off is slightly steeper (maximum difference of 5%) than the one generated by the P50 device with the 22 mm applicator.
A novel multichannel rectal applicator for contact radiotherapy with high-dose-rate Ir sources that can be integrated with commercially available treatment planning systems was designed to produce a dose distribution similar to the one obtained by the P50 device.
增加直肠肿瘤的照射剂量可提高完全缓解率，从而有可能省略手术。腔内增敏技术的重要优势包括，与使用外照射放疗相比，有可能进行更具选择性/局部性的增敏。设计了一种带有侧向屏蔽的新型近距离放射治疗（BT）直肠施源器，用于与直肠镜配合，进行眼视引导定位，以使用常用的高剂量率铱BT源，提供与接触式X射线放射治疗设备相似的剂量分布。
通过蒙特卡罗建模设计了一种带有侧向屏蔽的圆柱形多通道BT施源器，通过胶片剂量测定法进行实验验证，并与文献中关于Papillon 50（P50）接触式X射线放射治疗设备的直肠镜尺寸、辐射束形状、剂量衰减和治疗时间的结果进行比较。
所设计的多通道施源器使用20350 U（5居里）源，能够在13分钟内给予30 Gy的剂量。使用多个通道和侧向屏蔽可提供直径为22 mm的均匀圆形治疗表面。产生的剂量衰减比使用22 mm施源器的P50设备产生的剂量衰减略陡（最大差异为5%）。
设计了一种新型的用于接触式放疗的多通道直肠施源器，可与高剂量率铱源配合使用，并可与市售治疗计划系统集成，以产生与P50设备获得的剂量分布相似的剂量分布。
