磁场对^(60)Co放射治疗剂量影响的蒙特卡罗研究

A Monte Carlo Study of the Influence on the Dose Distribution by the Magnetic Field

针对磁共振引导放射治疗新技术,研究了磁场对^(60)Co放射治疗剂量的影响。建立了具有“水-空气-水”非均质结构的几何模型,通过蒙特卡罗程序TOPAS模拟射线与物质相互作用以及带电粒子在磁场中的输运过程。结果显示:磁场对^(60)Co光子剂量的影响主要集中在高密度区-低密度区的界面位置,界面位置高密度区剂量得到明显增高,且增高的趋势随着磁场强度增加更加明显;当界面位于模体不同深度处,磁场对剂量的影响程度也有不同。该研究结果可为磁共振引导^(60)Co放射治疗新技术的剂量评估提供一定理论基础。

Aiming at the new technology of magnetic resonance guided radiotherapy, the influence of magnetic field on the dose of^(60)Co radiotherapy was studied. A geometric model with a "water-air-water" heterogeneous structure is established, and the interaction between rays and matter and the transport of charged particles in a magnetic field are simulated by the Monte Carlo toolkit TOPAS. The results show that the influence of the magnetic field on the photon dose of^(60)Co is mainly concentrated in the interface between the high-density region and the low-density region. At different depths of the phantom, the effect of the magnetic field on the dose is also different. The results of this study can provide a theoretical basis for the dose assessment of the new technology of magnetic resonance-guided^(60)Co radiotherapy.