四维动态数字人体模型的开发及其在放疗计划中评估器官呼吸运动影响的研究

目的开发一种可以用于蒙特卡罗模拟的四维动态运动模型来研究不同放射治疗计划中器官运动造成的影响。方法本文阐述了一个用在放射治疗计划上来研究器官运动影响的四维数字化人体模型。该模型通过对器官控制点的采样和使用非均匀有理B样条方法,对现存的三维VIP-Man(visiblephotographicman)模型利用临床中得到的呼吸运动数据进行器官控制点的时间,空间变换,进而得到四维的数字化人体解剖模型。一种蒙特卡罗代码,EGS4(electrongammashower,version4),被用于对该四维VIP-Man模型进行放疗模拟。出于测试模型目的,我们模拟了四维VIP-Man左肺部产生一肿瘤,通过传统三维四束对穿(前,后,左,右)来模拟计算呼吸运动对肿瘤剂量分配的影响。结果在本次模拟研究中,从不同呼吸相位产生的剂量的差别可达40%。目标剂量容积直方图明显存在区别。结论初步的研究证明了四维数字人体模型用于蒙特卡罗模拟计算中的潜能。

Four-dimensional human modeling for respiratory motion and the impact on radiation treatment planning

Objective Developing a motion-simulating model for various radiation treatment plans to study the effects of organ motion using Monte Carlo simulations. Methods This paper presents a 4D digital anatomical model for studying effects of organ motion on radiation treatment and delivery. An existing 3D VIP-Man (visible photographic man) model has been reconstructed using sampled control points for organs and non-uniform rational B-splines (NURBS) method. Transformation on those control points, using the respiratory motion data obtained clinically, can be used to get the 4D partial-body anatomical model by time-dependent equations. EGS4 (electron gamma shower, version 4) code is used for Monte Carlo calculations. To test the model proposed, a simulation study of a lung lesion was created to study the impact of organ motion on delivered radiation dose. Results In this simulation study, the lesion dose could differ as much as 40% for different respiratory phases in the simulation study. Conclusion This preliminary study demonstrates the potential of 4D digital anatomical model utilizing Monte Carlo code for 4D dose calculations.