A direct voxel tracking method for four-dimensional Monte Carlo dose calculations in deforming anatomy
A direct voxel tracking method for four-dimensional Monte Carlo dose calculations in deforming anatomy
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DOI：
10.1118/1.2163252
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发表时间：
2006-02-01
期刊：
影响因子：
3.8
通讯作者：
Seuntjens, J
中科院分区：
文献类型：
--
作者：
Heath, E;Seuntjens, J
在这项工作中，我们提出了一种计算变形解剖学中剂量的方法，其中每个剂量体素的位置和形状随着解剖学的变化而被跟踪。修改了EGsnrc/Dosxyznrc蒙特卡罗程序，以根据从非线性图像配准算法获得的变形向量来计算变形的体素中的剂量。DefDOSXYZ代码通过一致性检查以及通过将计算与DOSXYZnrc计算进行比较来验证。将形变模体的计算结果与采用三线性插值法的剂量重映射方法进行了比较。用形变体素计算的剂量与DOSXYZnrc的计算在1%以内一致。在简单的变形矩形体模中，对于1.0 cm体素大小的视野，三线性剂量重映射方法被发现低估了高达29%的剂量，在剂量梯度较大的区域有较大的差异。两种计算方法之间的一致性有所提高，体素大小和变形幅度更小。在一个解剖呼吸模体中，从吸气到呼气的剂量重新映射的比较表明，使用三线性插值法，半影处的剂量形变被低估了16%，表面附近的剂量形变被低估了8%。(C)2006年美国医学物理学家协会。
In this work we present a method of calculating dose in deforming anatomy where the position and shape of each dose voxel is tracked as the anatomy changes. The EGsnrc/Dosxyznrc Monte Carlo code was modified to calculate dose in voxels that are deformed according to deformation vectors obtained from a nonlinear image registration algorithm. The defDOSXYZ code was validated by consistency checks and by comparing calculations against DOSXYZnrc calculations. Calculations in deforming phantoms were compared with a dose remapping method employing trilinear interpolation. Dose calculations with the deforming voxels agree with DOSXYZnrc calculations within 1%. In simple deforming rectangular phantoms the trilinear dose remapping method was found to underestimate the dose by up to 29% for a 1.0 cm voxel size within the field, with larger discrepancies in regions of steep dose gradients. The agreement between the two calculation methods improved with smaller voxel size and deformation magnitude. A comparison of dose remapping from Inhale to Exhale in an anatomical breathing phantom demonstrated that dose deformations are underestimated by up to 16% in the penumbra and 8% near the surface with trilinear interpolation. (c) 2006 American Association of Physicists in Medicine.