SU-E-T-553: Dose-Mass Vs. Dose-Volume Optimization: A Phantom Study.
SU-E-T-553: Dose-Mass Vs. Dose-Volume Optimization: A Phantom Study.
复制标题
SU-E-T-553：剂量-质量与。
DOI：
10.1118/1.4735642
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发表时间：
2012
期刊：
影响因子：
3.8
通讯作者：
Siebers,J
中科院分区：
文献类型：
--
作者：
Mihaylov,I;Moros,E;Siebers,J
方法将基于体积直方图(DVH)的二次目标函数转换为基于剂量质量直方图(DMH)的目标函数，将目标内的单位体素体积乘以单位体素密度。构建了一个1.0g/cm3靶靶的数字体模，用于两束照射：一条光路包含0.2g/cm3感兴趣体积(VOI0.2)，而正交光路包含等体积0.8g/cm3VOI(VOI0.8)。结果对于通过VOI0.2的单束照射，VOI0.2的平均剂量为20.5cGy.对于VOI0.8的单束照射，VOI0.8的平均剂量为25.2cGy。穿过低密度体积可使∼剂量降低23%。当执行基于DVH和DMH的优化以使优化的目标剂量-体积-直方图匹配时，对于DVH优化，60%与40%的剂量通过VOI0.2与VOI0.8传递。对于DMH优化，VOI0.2和VOI0.8提供的剂量之差分别为70%和30%。结论当密度不变时，DVH优化和DMH优化之间没有差异。然而，在非均匀介质中，当低密度和高密度材料具有相同的剂量目标时，DMH和DVH溶液不同。由于衰减材料的减少，通过低密度VOI传递靶剂量促进了靶剂量沉积，而衰减的减少降低了低密度VOI的剂量。从数学和物理的角度来看，剂量-质量优化比剂量-体积优化更具一般性。
PurposeTo demonstrate the merits of mass‐based optimization in comparison with volume‐based optimization using a simple test phantom.MethodsDose‐volume‐histogram‐based (DVH‐based) quadratic objective functions are converted into dose‐mass‐histogram‐based (DMH‐based) objective functions by multiplying per‐voxel volumes by per‐voxel densities within the objective. A digital phantom with a 1.0 g/cm3target is constructed for irradiation with two beams: one beam path contains a 0.2 g/cm3volume‐of‐interest (VOI0.2) while the orthogonal beam‐path contains an equal‐volume 0.8 g/cm3VOI (VOI0.8). Monitor‐units are computed to achieve a 100 cGy average target dose for each individual beam, and for two‐beam DVH‐based and DMH‐based optimizations.ResultsFor single‐beam irradiation through VOI0.2, the average dose to VOI0.2 is 20.5 cGy. For single‐beam irradiation through VOI0.8, the average dose to VOI0.8 is 25.2 cGy. Traversing the low density volume results in ∼23% lower dose. When DVH‐ and DMH‐based optimizations are performed such that target dose‐volume‐histograms of the optimizations match, for the DVH optimization 60% vs. 40% of the dose is delivered through VOI0.2 vs. VOI0.8. For DMH‐optimization, the split between dose delivered through VOI0.2 vs. VOI0.8 is 70% vs. 30%.ConclusionsWhen density is constant, there is no difference between DVH‐ and DMH‐based optimizations. However, in heterogeneous media, DMH and DVH solutions differ when low and high density materials have the same dose objectives. Delivering target dose through lower density VOIs facilitates target dose deposition due to a decrease in attenuating material, and the decreased attenuation lowers dose to the low density VOI. From mathematical and physical points of view dose‐mass optimization is more general than dose‐volume optimization.