Acceleration of dose calculations for intensity-modulated radiotherapy
Acceleration of dose calculations for intensity-modulated radiotherapy
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DOI：
10.1118/1.1373404
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发表时间：
2001-06-01
期刊：
影响因子：
3.8
通讯作者：
Mohan, R
中科院分区：
文献类型：
--
作者：
Siebers, JV;Tong, SD;Mohan, R
放射治疗剂量计算的精度和速度之间的要求和权衡已经讨论了几十年。用于调强放射治疗（IMRT）优化的逆向计划对剂量计算提出了额外的要求，因为它是一个迭代过程，其中剂量计算可能重复许多次（10次到1000次）。这项工作讨论了有关IMRT剂量计算的准确性和速度问题。提出并应用了一种加速优化过程的混合剂量计算方法，其中快速笔形束（PB）模型用于初始优化迭代，然后进行叠加/卷积（SC）计算。比较了纯PB优化、纯SC优化和PB优化后SC优化的优化剂量结果。计划进行了评价，在等剂量覆盖，剂量体积直方图，和总剂量计算时间的5个头部和颈部的情况下，不同的位置，大小和形状的肿瘤和关键结构。患者计划设计为九个等间距射束。对于1名患者，测试了额外的5束配置。我们发现，从所有计划产生的强度分布的总体特征是相似的，但有细微的细节差异。PB和SC方法优化的复合剂量分布之间的差异很小，但在个人束剂量分布的差异是相当显着的。当SC方法用于计算剂量与PB方法的优化后，剂量差异显着减少的复合计划和个人束。观察到大量的总体时间节省，使调强放射治疗剂量计划成为一个更具互动性的活动。(C)2001年美国医学物理学家协会。
The requirements and trade-offs between accuracy and speed for radiotherapy dose computations have been discussed for decades. Inverse planning used for intensity-modulated radiotherapy (IMRT) optimization imposes additional demands on dose calculation since it is an iterative process in which dose calculations might be repeated many (10's to 1000's) of times. This work discusses the accuracy and speed issues as related to IMRT dose calculations. A hybrid dose calculation method which accelerates the optimization process is proposed and applied in which a fast-pencil beam (PB) model is used for initial optimization iterations, followed by superposition/convolution (SC) calculations. Optimization dose results are compared for pure PB optimization, pure SC optimization, and PB optimization followed by SC optimization. Plans were evaluated in terms of isodose coverage, dose-volume histograms, and total dose calculation time for five head and neck cases with diverse locations, sizes, and shapes for tumors and critical structures. Patient plans were designed fur nine equispaced beams. For one patient, an additional five-beam configuration was tested. We found that gross features of intensity distributions resulting from all schemes were similar, however there were differences in the fine detail. Differences were small between composite dose distributions optimized with PB and SC methods, yet differences in individual beam dose distributions were quite significant. When the SC method was used to compute dose following optimization with PB method, dose differences were reduced significantly both for composite plans and for individual beams. Substantial overall timesavings were observed, allowing IMRT dose planning to become a more interactive activity. (C) 2001 American Association of Physicists in Medicine.