Johnson Daniel, Chen Yong, Ahmad Salahuddin
Department of Radiation Oncology, Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma 73104, USA.
J Med Phys. 2015 Oct-Dec;40(4):214-9. doi: 10.4103/0971-6203.170785.
The factors influencing carbon ion therapy can be predicted from accurate knowledge about the production of secondary particles from the interaction of carbon ions in water/tissue-like materials, and subsequently the interaction of the secondary particles in the same materials. The secondary particles may have linear energy transfer (LET) values that potentially increase the relative biological effectiveness of the beam. Our primary objective in this study was to classify and quantify the secondary particles produced, their dose averaged LETs, and their dose contributions in the absorbing material. A 1 mm diameter carbon ion pencil beam with energies per nucleon of 155, 262, and 369 MeV was used in a geometry and tracking 4 Monte Carlo simulation to interact in a 27 L water phantom containing 3000 rectangular detector voxels. The dose-averaged LET and the dose contributions of primary and secondary particles were calculated from the simulation. The results of the simulations show that the secondary particles that contributed a major dose component had LETs <100 keV/µm. The secondary particles with LETs >600 keV/µm contributed only <0.3% of the dose.
影响碳离子治疗的因素可以通过准确了解碳离子在水/类组织材料中相互作用产生次级粒子的情况，以及随后这些次级粒子在相同材料中的相互作用来预测。次级粒子的线能量转移（LET）值可能会提高束流的相对生物效应。本研究的主要目的是对产生的次级粒子进行分类和量化，确定其剂量平均LET值及其在吸收材料中的剂量贡献。在一个几何结构和跟踪4蒙特卡罗模拟中，使用了直径为1毫米、每个核子能量分别为155、262和369兆电子伏的碳离子笔形束，使其在一个装有3000个矩形探测器体素的27升水体模中相互作用。根据模拟计算了剂量平均LET以及初级和次级粒子的剂量贡献。模拟结果表明，构成主要剂量成分的次级粒子的LET值<100千电子伏/微米。LET值>600千电子伏/微米的次级粒子仅贡献了<0.3%的剂量。
