Designing a range modulator wheel to spread-out the Bragg peak for a passive proton therapy facility
Designing a range modulator wheel to spread-out the Bragg peak for a passive proton therapy facility
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DOI：
10.1016/j.nima.2015.10.006
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发表时间：
2016-01
影响因子：
1.4
通讯作者：
S. B. Jia;F. Romano;G. Cirrone;G. Cuttone;M. H. Hadizadeh;A. Mowlavi;L. Raffaele
中科院分区：
文献类型：
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作者：
S. B. Jia;F. Romano;G. Cirrone;G. Cuttone;M. H. Hadizadeh;A. Mowlavi;L. Raffaele
在质子束治疗中，使用外布拉格峰（SOBP）来在靶体积中建立均匀的剂量分布。为了创建SOBP，对应于不同入射能量的不同范围的具有一定强度（权重）的若干布拉格峰应彼此组合。在被动射束散射系统中，通常在整个治疗过程中以恒定能量从回旋加速器提取射束。因此，SOBP由范围调制器轮产生，该范围调制器轮基本上是具有可变厚度的台阶的旋转轮，或者通过使用脊形滤波器产生。在这项研究中，我们使用Geant4工具包来模拟一个典型的被动散射光束线。特别是，在卡塔尼亚的INFN Nazionali del Sud（LNS）的CATANA传输光束线已在这项工作中重现。一些初始属性的入射光束已检查基准模拟与实验数据。已经实现了一个专用于车轮调制器仿真的类。它已经被设计成易于修改，以模拟任何所需的调制器轮，因此，任何合适的光束调制。通过使用一些辅助的距离移位器，从模拟中获得了一组原始的布拉格峰。开发了一种数学算法，使用模拟的原始剂量曲线作为输入，以计算每个原始峰的权重，重现SOBP，并最终生成平坦的剂量分布。因此，一旦设计的调制器已经实现，它已在CATANA设施进行了测试，比较实验数据与仿真结果。
In proton beam therapy, a Spread-Out Bragg peak (SOBP) is used to establish a uniform dose distribution in the target volume. In order to create a SOBP, several Bragg peaks of different ranges, corresponding to different entrance energies, with certain intensities (weights) should be combined each other. In a passive beam scattering system, the beam is usually extracted from a cyclotron at a constant energy throughout a treatment. Therefore, a SOBP is produced by a range modulator wheel, which is basically a rotating wheel with steps of variable thicknesses, or by using the ridge filters. In this study, we used the Geant4 toolkit to simulate a typical passive scattering beam line. In particular, the CATANA transport beam line of INFN Laboratori Nazionali del Sud (LNS) in Catania has been reproduced in this work. Some initial properties of the entrance beam have been checked by benchmarking simulations with experimental data. A class dedicated to the simulation of the wheel modulators has been implemented. It has been designed in order to be easily modified for simulating any desired modulator wheel and, hence, any suitable beam modulation. By using some auxiliary range-shifters, a set of pristine Bragg peaks was obtained from the simulations. A mathematical algorithm was developed, using the simulated pristine dose profiles as its input, to calculate the weight of each pristine peak, reproduce the SOBP, and finally generate a flat dose distribution. Therefore, once the designed modulator has been realized, it has been tested at CATANA facility, comparing the experimental data with the simulation results.