A torus source and its application for non-primary radiation evaluation
A torus source and its application for non-primary radiation evaluation
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DOI：
10.1088/1361-6560/acede7
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发表时间：
2023-12-21
影响因子：
3.5
通讯作者：
Hong，Rui
中科院分区：
文献类型：
--
作者：
Cheng，Han-Long;Wang，Jin-Long;Hong，Rui
质子治疗对正常组织的非原发性辐射剂量可能与继发性恶性肿瘤的风险增加有关，特别是在长期生存者中。与传统的光子治疗系统不同，质子治疗系统是由多个子系统组成的，它们位于一个厚厚的掩体中。这些子系统都是威胁患者的非初级辐射的可能来源。作为一个案例研究，在P-Cure同步质子治疗系统中的7个源的蒙特卡罗（MC）代码建模：串联注入器，注入，同步加速器环，提取，束流传输线，扫描喷嘴和混凝土反射/散射。为了准确计算同步辐射束流损失和非初始剂量，提出了一种新的辐射源环模型。其参数方程定义了笛卡尔坐标系中离轨粒子轰击环面管壳的位置和方向。主要结果在15-50 cm和50-200 cm范围内，不同来源的非原发剂量与计划剂量2戈伊的比值均远小于IEC要求。因此，P-Cure同步加速器质子治疗系统是一种清洁、友好的质子治疗系统，加速器和患者之间不需要内部屏蔽混凝土。意义非原发辐射剂量水平是评价质子治疗系统质量的一个非常重要的指标。本文提出了一种新的束流损失模型，为基于同步加速器的质子治疗提供了一种可行的MC过程。这可以帮助人们在系统投入临床治疗之前准确地确定该水平是否符合IEC标准。此外，环面源模型还可广泛应用于门架和同步加速器中的弯曲磁体，以评估非初级剂量或其他辐射剂量。
ObjectiveNon-primary radiation doses to normal tissues from proton therapy may be associated with an increased risk of secondary malignancies, particularly in long-term survivors. Thus, a systematic method to evaluate if the dose level of non-primary radiation meets the IEC standard requirements is needed.ApproachDifferent from the traditional photon radiation therapy system, proton therapy systems are composed of several subsystems in a thick bunker. These subsystems are all possible sources of non-primary radiation threatening the patient. As a case study, 7 sources in the P-Cure synchrotron-based proton therapy system are modeled in Monte Carlo (MC) code: tandem injector, injection, synchrotron ring, extraction, beam transport line, scanning nozzle and concrete reflection/scattering. To accurately evaluate the synchrotron beam loss and non-primary dose, a new model called the torus source model is developed. Its parametric equations define the position and direction of the off-orbit particle bombardment on the torus pipe shell in the Cartesian coordinate system. Non-primary doses are finally calculated by several FLUKA simulations.Main resultsThe ratios of summarized non-primary doses from different sources to the planned dose of 2 Gy are all much smaller than the IEC requirements in both the 15–50 cm and 50–200 cm regions. Thus, the P-Cure synchrotron-based proton therapy system is clean and patient-friendly, and there is no need an inner shielding concrete between the accelerator and patient.SignificanceNon-primary radiation dose level is a very important indicator to evaluate the quality of a PT system. This manuscript provides a feasible MC procedure for synchrotron-based proton therapy with new beam loss model. Which could help people figure out precisely whether this level complies with the IEC standard before the system put into clinical treatment. What'more, the torus source model could be widely used for bending magnets in gantries and synchrotrons to evaluate non-primary doses or other radiation doses.