MRI-Linac剂量测量研究进展

Research progress in dosimetry with MRI-Linac

MRI-Linac一体机实现了MRI实时引导放疗,加快了精确放疗进展。磁场中电子受到洛伦兹力作用,尤其是在组织-空气界面处出现电子回旋效应,改变了原有的电子平衡状态,这给MRI-Linac下的剂量测量带来挑战。近年来通过蒙特卡洛模拟和实验测量开展的系列研究表明常规剂量测量装置进行磁性材料替换后,即可以用于MRI-Linac下的剂量测量,但需要根据磁场强度、测量装置摆放角度、测量装置类型引入相应的修正因子。MRI-Linac下剂量测量的规范化、流程化以及实时剂量测量有待进一步研究。

The integration of MRI and linac has realized real-time MRI-guided radiotherapy and accelerated the progress of precision radiotherapy.Electrons are subjected to Lorentz force in the magnetic field,especially the electron cyclotron effect occurs at the tissue-air interface,which changes the original electron equilibrium state and brings challenges to dosimetry with MRI-Linac.In recent years,a series of studies carried out through Monte Carlo simulation and experimental measurement have suggested that the conventional dosimetry devices can be used for the dosimetry with MRI-Linac after replacing the magnetic materials,but corresponding correction factors should be introduced according to the magnetic field intensity,placement angle of the measuring device,type of the measuring device.The standardization,streamlining,and real-time dosimetry with MRI-Linac need to be further studied.