Leite A M M, Ronga M G, Giorgi M, Ristic Y, Perrot Y, Trompier F, Prezado Y, Créhange G, De Marzi L
Institut Curie, PSL Research University, Radiation Oncology Department, Proton Therapy Centre, Centre Universitaire, F-91898 Orsay, France.
Institut Curie, PSL Research University, University Paris Saclay, Inserm U 1021- CNRS UMR 3347, F-91898 Orsay, France.
Phys Med Biol. 2021 Nov 24;66(22). doi: 10.1088/1361-6560/ac3209.
The Orsay Proton therapy Center (ICPO) has a long history of intracranial radiotherapy using both double scattering (DS) and pencil beam scanning (PBS) techniques, and is actively investigating a promising modality of spatially fractionated radiotherapy using proton minibeams (pMBRT). This work provides a comprehensive comparison of the organ-specific secondary neutron dose due to each of these treatment modalities, assessed using Monte Carlo (MC) algorithms and measurements. A MC model of a universal nozzle was benchmarked by comparing the neutron ambient dose equivalent,(10), in the gantry room with measurements obtained using a WENDI-II counter. The secondary neutron dose was evaluated for clinically relevant intracranial treatments of patients of different ages, in which secondary neutron doses were scored in anthropomorphic phantoms merged with the patients' images. The MC calculated(10) values showed a reasonable agreement with the measurements and followed the expected tendency, in which PBS yields the lowest dose, followed by pMBRT and DS. Our results for intracranial treatments show that pMBRT yielded a higher secondary neutron dose for organs closer to the target volume, while organs situated furthest from the target volume received a greater quantity of neutrons from the passive scattering beam line. To the best of our knowledge, this is the first study to compare MC secondary neutron dose estimates in clinical treatments between these various proton therapy modalities and to realistically quantify the secondary neutron dose contribution of clinical pMBRT treatments. The method established in this study will enable epidemiological studies of the long-term effects of intracranial treatments at ICPO, notably radiation-induced second malignancies.
奥赛质子治疗中心（ICPO）在使用双散射（DS）和笔形束扫描（PBS）技术进行颅内放射治疗方面有着悠久的历史，并且正在积极研究一种有前景的使用质子微束（pMBRT）进行空间分割放射治疗的模式。这项工作全面比较了这些治疗模式各自产生的器官特异性次级中子剂量，使用蒙特卡罗（MC）算法和测量进行评估。通过将龙门室中的中子周围剂量当量*（10）与使用WENDI-II计数器获得的测量值进行比较，对通用喷嘴的MC模型进行了基准测试。针对不同年龄患者的临床相关颅内治疗评估了次级中子剂量，其中在与患者图像合并的人体模型中对次级中子剂量进行了评分。MC计算的*（10）值与测量值显示出合理的一致性，并遵循预期趋势，其中PBS产生的剂量最低，其次是pMBRT和DS。我们关于颅内治疗的结果表明，对于更靠近靶体积的器官，pMBRT产生的次级中子剂量更高，而距离靶体积最远的器官从被动散射束线接收的中子数量更多。据我们所知，这是第一项比较这些不同质子治疗模式在临床治疗中MC次级中子剂量估计值并实际量化临床pMBRT治疗的次级中子剂量贡献的研究。本研究中建立的方法将能够对ICPO颅内治疗的长期影响进行流行病学研究，特别是辐射诱发的第二原发性恶性肿瘤。
