基于危及器官预测剂量分布与gEUD混合目标的调强放疗计划优化

目的 提出一种可充分利用危及器官预测剂量分布信息，同时最大限度地改善输出计划质量的调强放疗计划优化方法。方法 构建以危及器官预测剂量分布作为优化引导的新型通量分布优化模型，考虑到预测的不确定性，模型中同时耦合了危及器官的等效均匀剂量目标（gEUD）以在预测引导的基础上进一步改善最优化求解空间。为验证优化方法的有效性，实验选取8例宫颈癌调强放射治疗（IMRT）计划，利用该方法对其重新优化后比较所得计划与原始计划间在剂量分布和特定剂量学指征项上的质量差异。结果 该优化方法具有可行解且收敛快速，所得优化计划与原始计划相比，靶区内热点减少，其剂量均匀性提高；危及器官受量也均有改善，直肠V₃₀和V₄₅分别减小了（6.60±3.53）%和（17.03±7.44）%，差异有统计学意义（t=-4.954、-6.055，P<0.05），膀胱V₃₀和V₄₅分别减小（14.74±5.61）%和（14.99±4.53）%，差异有统计学意义（t=-6.945、-8.759，P<0.05）。结论 所提出的基于预测剂量分布和gEUD混合目标的调强放疗计划优化方法可有效地利用预测剂量分布，并保障输出计划的优质性。

OAR predicted dose distribution and gEUD based treatment planning optimization for IMRT

Objective To propose a treatment planning optimization algorithm which can make full use of OAR dose distribution prediction meanwhile improving the output planning quality as much as possible. Methods We had reformulated an FMO function under the guidance of dose distribution prediction and also integrated equivalent uniform dose (gEUD) based on the consideration of prediction uncertainty, for providing optimal solution. Performance of the method was evaluated by comparing the optimized IMRT plan quality of 8 cervical cancers in the term of DVH curves, dose distribution and dosimetric endpoints with the original ones. Results The proposed method had a feasible, fast solution. Compared with original plan, its output plan had better plan quality in better dose homogeneity, less hot spot and further dose sparing for OARs. V₃₀, V₄₅ of rectum was decreased by (6.60±3.53)% and (17.03±7.44)%, respectively, with the statistically significant difference (t=-4.954,-6.055, P<0.05). V₃₀, V₄₅ of bladder was decreased by (14.74±5.61)% and (14.99±4.53)%, respectively, with the statistically significant difference (t=-6.945,-8.759, P<0.05). Conclusions We have successfully developed a predicted dose distribution and equivalent uniform dose-based planning optimization method, which is able to make good use of 3D dose prediction and ensure the output plan quality for intensity modulated radiation therapy.