Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
Int J Radiat Biol. 2012 Jan;88(1-2):209-12. doi: 10.3109/09553002.2011.595877. Epub 2011 Jul 19.
Stopping-power data enter at a number of different places in particle therapy and their uncertainties have a direct impact on the accuracy of the therapy, e.g., in treatment planning. Furthermore, for clinical quality assurance, the particle beam stopping-power ratios (STPR) have to be known accurately for dosimetry.
An open-source computer library called libdEdx (library for energy loss per unit path length, dE/dx, calculations) is developed, providing stopping-power data from data tables and computer programs as well as a stopping-power formula comprising a large list of target materials. Calculations of STPR in the case of spread-out Bragg-peaks (SOBP) are performed with the Monte Carlo transportation code SHIELD-HIT (SHIELD-Heavy Ion Transport) using different ions relevant for particle therapy.
For SOBP the water-to-air STPR depends on the residual range and is qualitatively very similar for different ions; however, small quantitative differences exist between the considered ion species.
libdEdx allows for a convenient and efficient treatment of stopping powers in numerical applications. It can be applied to estimate the dependence on the accuracy of the stopping power and to provide data for an extended number of target materials. The STPR for SOBP for different ions are found to be qualitatively the same which may allow for an analytical description valid for all ions.
在粒子治疗中，阻止本领数据出现在许多不同的地方，其不确定性直接影响治疗的准确性，例如在治疗计划中。此外，对于临床质量保证，粒子束阻止本领比（STPR）必须准确用于剂量测定。
开发了一个名为 libdEdx（用于能量损失与单位路径长度比（dE/dx）计算的开源计算机库）的开源计算机库，提供了来自数据表和计算机程序的阻止本领数据以及一个包含大量目标材料的阻止本领公式。使用与粒子治疗相关的不同离子，通过蒙特卡罗输运代码 SHIELD-HIT（SHIELD-Heavy Ion Transport）对扩展布拉格峰（SOBP）中的 STPR 进行计算。
对于 SOBP，水到空气的 STPR 取决于残余射程，对于不同的离子定性上非常相似；然而，在考虑的离子种类之间存在微小的定量差异。
libdEdx 允许在数值应用中方便有效地处理阻止本领。它可用于估计对阻止本领精度的依赖性，并为大量目标材料提供数据。不同离子的 SOBP 的 STPR 定性上是相同的，这可能允许对所有离子都有效的分析描述。
