Physical and biophysical properties of proton tracks of energies 1 keV to 300 MeV in water
Physical and biophysical properties of proton tracks of energies 1 keV to 300 MeV in water
复制标题
水中能量为 1 keV 至 300 MeV 的质子径迹的物理和生物物理特性
DOI：
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发表时间：
2011
影响因子：
2.6
通讯作者：
H. Nikjoo
中科院分区：
文献类型：
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作者：
T. Liamsuwan;S. Uehara;D. Emfietzoglou;H. Nikjoo
目的：用蒙特卡罗径迹结构方法研究1 keV-300 MeV质子径迹的物理和生物物理性质。 材料和方法：我们目前的模型计算的横截面和方法模拟全慢质子轨道。 考虑到弹性散射、电离、激发和电荷转移，质子和电子被逐个相互作用地跟踪到截止能量。结果：模型计算的单微分和总截面，路径长度和阻止功率作为衡量的代码评估。 160 MeV质子的深度剂量分布与实验数据进行了比较。由电子相互作用引起的能量损失频率从10 keV的1.3%增加到300 MeV质子的1.77%，并且电子存款>70%的剂量在160 MeV轨道中。 从微剂量计算，1 MeV的质子被发现是更有效的比5-300 MeV的能量沉积大于25，50，和500 eV的直径和长度分别为2，10，和100 nm的圆柱体。对于低能沉积，高能质子更有效。减小靶的尺寸会导致<1 MeV的质子的频率和剂量平均线性能量的降低，而对于更高能量的质子则相反。结论：在分子水平上的质子轨道的描述有利于轨道的性质，能量损失和微剂量学参数的辐射生物物理学，放射治疗和空间辐射研究的调查。
Purpose: To investigate physical and biophysical properties of proton tracks 1 keV–300 MeV using Monte Carlo track structure methods. Materials and methods: We present model calculations for cross sections and methods for simulations of full-slowing-down proton tracks. Protons and electrons were followed interaction-by-interaction to cut-off energies, considering elastic scattering, ionisation, excitation, and charge-transfer. Results: Model calculations are presented for singly differential and total cross sections, and path lengths and stopping powers as a measure of the code evaluation. Depth-dose distributions for 160 MeV protons are compared with experimental data. Frequencies of energy loss by electron interactions increase from ∼3% for 10 keV to ∼77% for 300 MeV protons, and electrons deposit >70% of the dose in 160 MeV tracks. From microdosimetry calculations, 1 MeV protons were found to be more effective than 5–300 MeV in energy depositions greater than 25, 50, and 500 eV in cylinders of diameters and lengths 2, 10, and 100 nm, respectively. For lower-energy depositions, higher-energy protons are more effective. Decreasing the target size leads to the reduction of frequency- and dose-mean lineal energies for protons <1 MeV, and conversely for higher-energy protons. Conclusions: Descriptions of proton tracks at molecular levels facilitate investigations of track properties, energy loss, and microdosimetric parameters for radiation biophysics, radiation therapy, and space radiation research.