Newhauser Wayne D, Rechner Laura, Mirkovic Dragan, Yepes Pablo, Koch Nicholas C, Titt Uwe, Fontenot Jonas D, Zhang Rui
The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030, USA ; The University of Texas Graduate School of Biomedical Sciences at Houston, 6767 Bertner, Houston, TX 77030, USA ; Department of Medical Physics, Mary Bird Perkins Cancer Center, Baton Rouge, LA, 70809, USA.
The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030, USA ; The University of Texas Graduate School of Biomedical Sciences at Houston, 6767 Bertner, Houston, TX 77030, USA.
Radiat Meas. 2013 Nov 1;58:37-44. doi: 10.1016/j.radmeas.2013.08.001.
Monte Carlo simulations are increasingly used for dose calculations in proton therapy due to its inherent accuracy. However, dosimetric deviations have been found using Monte Carlo code when high density materials are present in the proton beam line. The purpose of this work was to quantify the magnitude of dose perturbation caused by metal objects. We did this by comparing measurements and Monte Carlo predictions of dose perturbations caused by the presence of small metal spheres in several clinical proton therapy beams as functions of proton beam range, spread-out Bragg peak width and drift space. Monte Carlo codes MCNPX, GEANT4 and Fast Dose Calculator (FDC) were used. Generally good agreement was found between measurements and Monte Carlo predictions, with the average difference within 5% and maximum difference within 17%. The modification of multiple Coulomb scattering model in MCNPX code yielded improvement in accuracy and provided the best overall agreement with measurements. Our results confirmed that Monte Carlo codes are well suited for predicting multiple Coulomb scattering in proton therapy beams when short drift spaces are involved.
由于其固有的准确性，蒙特卡罗模拟在质子治疗的剂量计算中越来越多地被使用。然而，当质子束流线路中存在高密度材料时，使用蒙特卡罗代码会发现剂量偏差。这项工作的目的是量化由金属物体引起的剂量扰动的大小。我们通过比较几种临床质子治疗束中小金属球存在时剂量扰动的测量值和蒙特卡罗预测值来做到这一点，这些剂量扰动是质子束射程、扩展布拉格峰宽度和漂移空间的函数。使用了蒙特卡罗代码MCNPX、GEANT4和快速剂量计算器（FDC）。测量值和蒙特卡罗预测值之间总体上有良好的一致性，平均差异在5%以内，最大差异在17%以内。MCNPX代码中多次库仑散射模型的修改提高了准确性，并与测量值提供了最佳的总体一致性。我们的结果证实，当涉及短漂移空间时，蒙特卡罗代码非常适合预测质子治疗束中的多次库仑散射。
