Beam angle selection incorporation of anatomical heterogeneities for pencil beam scanning charged-particle therapy.
Beam angle selection incorporation of anatomical heterogeneities for pencil beam scanning charged-particle therapy.
复制标题
笔形束扫描带电粒子治疗中结合解剖异质性的束角选择。
DOI：
10.1088/1361-6560/61/24/8664
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发表时间：
2016
影响因子：
3.5
通讯作者：
T
中科院分区：
文献类型：
--
作者：
Toramatsu;C., Inaniwa;T
在使用笔形束扫描（PBS）的带电粒子治疗中，布拉格峰中的剂量的局部化使得剂量分布对横向组织异质性敏感。PBS计划对横向组织异质性的敏感性可以通过选择适当的射束角度来降低。本研究的目的是发展一种快速准确的PBS光束角度选择方法。在给定的角度的笔形光束的路径周围的横向组织异质性进行量化与异质性数表示的布拉格峰深度的变化，使用的停止功率比的身体组织相对于水的光束的横截面。为了缩短计算时间，一维剂量优化进行了沿着的中心轴的笔形束，因为他们是由扫描磁铁。针对所有可能的治疗射束角度推导异质性数值。选择导致最小平均异质性数的角度作为最佳射束角度。三个头颈癌的临床病例被用来评估开发的方法。对所有测试角度的剂量分布及其对设置和范围误差的稳健性进行了评价，并研究了其与异质性数量的关系。在评价的病例中，平均异质性数量在1.2 mm-10.6 mm之间变化。通过选择具有低平均异质性数的射野，提高了靶剂量覆盖率和对设置和范围误差的稳健性。该方法简单、快速、准确，适用于PBS带电粒子治疗中束流角度的选择。
In charged particle therapy with pencil beam scanning (PBS), localization of the dose in the Bragg peak makes dose distributions sensitive to lateral tissue heterogeneities. The sensitivity of a PBS plan to lateral tissue heterogeneities can be reduced by selecting appropriate beam angles. The purpose of this study is to develop a fast and accurate method of beam angle selection for PBS. The lateral tissue heterogeneity surrounding the path of the pencil beams at a given angle was quantified with the heterogeneity number representing the variation of the Bragg peak depth across the cross section of the beams using the stopping power ratio of body tissues with respect to water. To shorten the computation time, one-dimensional dose optimization was conducted along the central axis of the pencil beams as they were directed by the scanning magnets. The heterogeneity numbers were derived for all possible beam angles for treatment. The angles leading to the minimum mean heterogeneity number were selected as the optimal beam angle. Three clinical cases of head and neck cancer were used to evaluate the developed method. Dose distributions and their robustness to setup and range errors were evaluated for all tested angles, and their relation to the heterogeneity numbers was investigated. The mean heterogeneity number varied from 1.2 mm–10.6 mm in the evaluated cases. By selecting a field with a low mean heterogeneity number, target dose coverage and robustness against setup and range errors were improved. The developed method is simple, fast, accurate and applicable for beam angle selection in charged particle therapy with PBS.