Cavallone Marco, Prezado Yolanda, De Marzi Ludovic
Centre de Protonthérapie d'Orsay, Department of Radiation Oncology, Institut Curie, Campus Universitaire, PSL Research University, 91898 Orsay, France.
Institut Curie, Université PSL, CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, 91400 Orsay, France.
Cancers (Basel). 2021 Dec 22;14(1):26. doi: 10.3390/cancers14010026.
Proton MiniBeam Radiation Therapy (pMBRT) is a novel strategy that combines the benefits of minibeam radiation therapy with the more precise ballistics of protons to further optimize the dose distribution and reduce radiation side effects. The aim of this study is to investigate possible strategies to couple pMBRT with dipole magnetic fields to generate a converging minibeam pattern and increase the center-to-center distance between minibeams. Magnetic field optimization was performed so as to obtain the same transverse dose profile at the Bragg peak position as in a reference configuration with no magnetic field. Monte Carlo simulations reproducing realistic pencil beam scanning settings were used to compute the dose in a water phantom. We analyzed different minibeam generation techniques, such as the use of a static multislit collimator or a dynamic aperture, and different magnetic field positions, i.e., before or within the water phantom. The best results were obtained using a dynamic aperture coupled with a magnetic field within the water phantom. For a center-to-center distance increase from 4 mm to 6 mm, we obtained an increase of peak-to-valley dose ratio and decrease of valley dose above 50%. The results indicate that magnetic fields can be effectively used to improve the spatial modulation at shallow depth for enhanced healthy tissue sparing.
质子微束放射治疗（pMBRT）是一种将微束放射治疗的优势与质子更精确的弹道学相结合的新策略，以进一步优化剂量分布并减少放射副作用。本研究的目的是研究将pMBRT与偶极磁场相结合以产生会聚微束模式并增加微束之间中心距的可能策略。进行磁场优化以在布拉格峰位置获得与无磁场的参考配置相同的横向剂量分布。使用再现实际笔形束扫描设置的蒙特卡罗模拟来计算水模体中的剂量。我们分析了不同的微束产生技术，例如使用静态多缝准直器或动态孔径，以及不同的磁场位置，即在水模体之前或内部。使用与水模体内的磁场相结合的动态孔径获得了最佳结果。对于中心距从4毫米增加到6毫米的情况，我们获得了峰谷剂量比的增加以及谷剂量降低超过50%。结果表明，磁场可有效地用于改善浅深度处的空间调制，以增强对健康组织的保护。
