Medical Physics Unit, McGill University, Montreal General Hospital, Montreal, Quebec, Canada.
Phys Med Biol. 2012 Jun 7;57(11):3259-72. doi: 10.1088/0031-9155/57/11/3259. Epub 2012 May 9.
The potential benefit of using scattering foil free beams for delivery of modulated electron radiotherapy is investigated in this work. Removal of the scattering foil from the beamline showed a measured bremsstrahlung tail dose reduction just beyond R(p) by a factor of 12.2, 6.9, 7.4, 7.4 and 8.3 for 6, 9, 12, 16 and 20 MeV beams respectively for 2 × 2 cm(2) fields defined on-axis when compared to the clinical beamline. Monte Carlo simulations were matched to measured data through careful tuning of source parameters and the modification of certain accelerator components beyond the manufacturer's specifications. An accelerator model based on the clinical beamline and one with the scattering foil removed were imported into a Monte Carlo-based treatment planning system (McGill Monte Carlo Treatment Planning). A treatment planning study was conducted on a test phantom consisting of a PTV and two distal organs at risk (OAR) by comparing a plan using the clinical beamline to a plan using a scattering foil free beamline. A DVH comparison revealed that for quasi-identical target coverage, the volume of each OAR receiving a given dose was reduced, thus reducing the dose deposited in healthy tissue.
本工作研究了在调制电子放射治疗中使用无散射箔自由束传输的潜在益处。从束流线上移除散射箔后，在轴上 2×2cm² 射野下，对于 6、9、12、16 和 20MeV 的束流，分别测量到 12.2、6.9、7.4、7.4 和 8.3 的 Bremsstrahlung 尾部剂量减少，与临床束线相比。通过仔细调整源参数并根据制造商的规格修改某些加速器组件，蒙特卡罗模拟与测量数据相匹配。基于临床束线和移除散射箔的加速器模型被导入到基于蒙特卡罗的治疗计划系统（McGill Monte Carlo Treatment Planning）中。通过将使用临床束线的计划与使用无散射箔自由束线的计划进行比较，对一个由 PTV 和两个远端危及器官（OAR）组成的测试体模进行了治疗计划研究。DVH 比较表明，对于近乎相同的靶区覆盖，每个 OAR 接受给定剂量的体积减小，从而减少了健康组织中的剂量沉积。
