剂量计算分辨率对肺部放射治疗剂量准确性的影响。第一部分。肺部的蒙特卡罗模型。

The effects of dose calculation resolution on dose accuracy for radiation therapy treatments of the lung. Part I. A Monte Carlo model of the lung.

机构信息

Department of Physics, University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada.

出版信息

Med Phys. 2010 Feb;37(2):675-86. doi: 10.1118/1.3285042.

DOI:10.1118/1.3285042

PMID:20229877

Abstract

PURPOSE

The purpose of this work was to create an anatomically detailed EGSnrc Monte Carlo based model of the right lung. The resulting model, called BRANCH, includes an accurate representation of the right bronchial, arterial, and venous branching networks down to a scale of 0.1 mm. The model may be varied to represent lung shape and density at any phase of the respiration cycle.

METHODS

Polynomial surfaces were used to approximate the anatomic boundaries that define the right lung surface at several phases of the respiration cycle. A branching network algorithm was used to generate the bronchial, arterial, and venous trees within the anatomic boundaries. The branching networks were modeled as a series of bifurcating cylinders connected by spherical junctions. The validity of the BRANCH dose calculation was verified using an all-water version of the model.

RESULTS

The geometric dimensions of the BRANCH model corresponded well with published data. The bronchial tree model contained 27 798 branches ranging from 0.02 to 0.54 cm in diameter. The arterial tree model had 27,957 branches ranging from 0.02 to 1.2 cm in diameter. The venous model tree had 26 347 branches ranging from 0.02 to 0.34 cm in diameter. A gamma analysis indicated that the all-water BRANCH Monte Carlo code produced dose distributions that agreed within 0.1 cm and 0.5% to conventional DOSXYZnrc results.

CONCLUSIONS

The BRANCH model is a useful tool for performing detailed dosimetric studies within a realistic representation of the lung.

摘要

目的

本研究旨在创建一个基于 EGSnrc Monte Carlo 的解剖学上详细的右肺模型。该模型名为 BRANCH，能够精确地表示右支气管、动脉和静脉的分支网络，达到 0.1 毫米的尺度。该模型可以根据呼吸周期的任何阶段来改变，以表示肺的形状和密度。

方法

使用多项式曲面来近似定义呼吸周期几个阶段的右肺表面的解剖边界。使用分支网络算法在解剖边界内生成支气管、动脉和静脉树。分支网络建模为通过球形连接连接的分叉圆柱的系列。BRANCH 剂量计算的有效性通过全水模型进行验证。

结果

BRANCH 模型的几何尺寸与发表的数据吻合良好。支气管树模型包含 27988 个分支，直径从 0.02 到 0.54 厘米不等。动脉树模型有 27957 个分支，直径从 0.02 到 1.2 厘米不等。静脉模型树有 26347 个分支，直径从 0.02 到 0.34 厘米不等。伽马分析表明，全水 BRANCH Monte Carlo 代码生成的剂量分布与传统 DOSXYZnrc 结果在 0.1 厘米和 0.5%以内一致。