基于TPS和蒙特卡罗计算的12C肿瘤放射治疗In-beam PET剂量监测研究

In-beam PET成像是碳离子放射治疗剂量监测的有效手段，可以对碳离子放疗过程的物理剂量分布和生物剂量分布进行实时监测。结合放射治疗计划系统(TPS)和蒙特卡罗(MC)模拟分别对静态均匀水模体和腹部肿瘤CT图像进行治疗计划设计、MC计算和PET成像，比较TPS肿瘤靶区剂量分布、MC模拟剂量分布和PET成像三者之间的一致性。TPS和MC模拟中相对生物学效应(RBE)的计算均采用线性二次模型(LQ)。研究结果显示，TPS和MC计算的静态均匀水模体、单野治疗腹部肿瘤的物理剂量、RBE加权剂量在SOBP区域的平均误差均在0.5%和2%以内。碳离子束流能量为120~400 MeV/u时，束流方向剂量深度分布与PET成像在SOBP区域的位置差异均在8 mm以内。In-beam PET可作为碳离子放射治疗中位置验证和剂量验证的有效手段。

In-beam PET Dose Monitoring Study of 12C Tumor Radiotherapy Based on TPS and Monte Carlo Calculation

In-beam PET imaging provides an effective method to monitor the physical and biological dose distribution during carbon ion radiotherapy in real time. We investigate the dose distribution and In-beam PET image of a homogeneous water phantom and an abdominal tumor CT phantom by the Treatment Planning System(TPS) and Monte Carlo(MC) simulation. We compare the consistency of TPS dose distribution, the MC simulation dose distribution and the PET imaging profile at the tumor area. The relative biological effect values(RBE) were calculated using a linear quadratic model(LQ). Results show that the average error of the physical dose and RBE weighted dose in the water phantom and the abdominal tumor CT phantom were within 0.5% and 2% respectively. The carbon ion energy ranges from 120 to 400 MeV/u. The peak position difference between dose and PET imaging is within 8 mm. This paper proves the feasibility of using In-beam PET for dose monitoring during carbon ion radiotherapy.