Performance of a hybrid MC dose algorithm for IMRT optimization dose evaluation.
Performance of a hybrid MC dose algorithm for IMRT optimization dose evaluation.
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DOI：
10.1118/1.2745236
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发表时间：
2007-07
期刊：
影响因子：
3.8
通讯作者：
J. Siebers;I. Kawrakow;Viswanathan Ramakrishnan
中科院分区：
文献类型：
--
作者：
J. Siebers;I. Kawrakow;Viswanathan Ramakrishnan
本文提出了一种混合调强放射治疗（IMRT）优化策略，结合笔形束（PB）的速度和蒙特卡罗（MC）剂量计算的准确性。在使用PB算法进行初始的基于可输送量的优化之后，使用VMC++ MC代码重新计算剂量以确定剂量校正因子，然后在进一步的基于PB的优化期间使用剂量校正因子。混合方法的基准相对于10个前列腺和10个头颈部调强放射治疗计划的完全MC可交付的优化。最后优化的计划进行比较，在剂量-体积指数用于计划优化。剂量预测误差（DPE）和优化收敛误差（OCE）的混合序列的中间步骤进行了评价。混合方法被发现，以产生优化的计划，在临床上相当于完全MC为基础的优化，但只需要40%的MC剂量计算的数量。使用本文提出的混合策略，在适度的计算集群上在35分钟或更短的时间内实现基于MC的优化结果。虽然发现初始的基于PB-可交付物的优化相对于65-73戈伊处方剂量具有高达3戈伊的DPE和OCE，但是第一次MC校正的应用将前列腺计划的平均DPE降低到小于0.3戈伊，并且将头颈部计划的平均DPE降低到小于0.06戈伊。1 MC剂量校正后，观察到的最大DPE或OCE为0.7戈伊，表明单次MC剂量计算校正可能足以进行IMRT优化。
This paper presents a hybrid intensity modulated radiation therapy (IMRT) optimization strategy which combines the speed of pencil beam (PB) and the accuracy of Monte Carlo (MC) dose calculations. After an initial deliverable-based optimization using a PB algorithm, doses are recomputed using the VMC++ MC code to determine dose correction factors, which are then utilized during further PB-based optimization. The hybrid method is benchmarked with respect to full MC deliverable-based optimization for ten prostate and ten head-and-neck IMRT plans. Final optimized plans are compared in terms of dose-volume indices used for the plan optimization. Dose prediction errors (DPEs) and optimization convergence errors (OCEs) at intermediate steps of the hybrid sequence are evaluated. The hybrid method is found to produce optimized plans that are clinically equivalent to full MC-based optimization, yet requires only 40% of the number of MC dose calculations. With the hybrid strategy presented here, MC-based optimization results are achieved in 35 min or less on a modest computing cluster. While the initial PB-deliverable-based optimization is found to have DPEs and OCEs of up to 3 Gy relative to the 65-73 Gy prescription doses, application of the first MC correction reduces the average DPEs to less than 0.3 Gy for the prostate plans and less than 0.06 Gy for the head and neck plans. The maximum observed DPE or OCE is 0.7 Gy after 1 MC dose correction, indicating that a single MC dose calculation correction might be sufficient for IMRT optimization.