Institut de Cancérologie de l'Ouest, Centre Paul Papin, 49055 Angers, France.
Institut de Sciences et Techniques de l'Ingénieur d'Angers, 49000 Angers, France.
Phys Med. 2019 May;61:103-111. doi: 10.1016/j.ejmp.2019.04.014. Epub 2019 May 3.
Design of experiments (DoE) provides a methodology to reveal the influence of input values on the measured output with a limited number of trials. The purpose of this study was to describe how DoE can be used to evaluate the performances of several dose calculation systems in heterogeneous media, including algorithms like Pencil Beam (PB), Anisotropic Analytical Algorithm (AAA), Acuros XB (AXB), Monte Carlo (MC) and Collapsed Cone Volume (CCV).
This study was carried out using a CIRS Model 002LFC IMRT Thorax Phantom customized with a water-equivalent heterogeneity inside the lung. The calculated dose distributions were compared to Gafchromic® EBT3 film measurements. The beam configurations were selected using DoE to study the influence of five parameters simultaneously (energy, collimator angulation, gantry angulation, X and Y jaws) and to optimize the number of experiments. An analysis of variance was performed over the entire irradiation field and over various regions of interest (tumour, shadow of tumour and lungs).
DoE enabled to quantify and determine the statistically significant factors, leading to an evaluation of the dose calculation systems in the lung case. The resulting scoring could be as follow (from best to worst): AXB_D, CCV, AXB_D, XVMC_D, XVMC_D, AAA and last PB. Differences between the algorithms were specially observed in the tumour and the shadow regions.
DoE is a robust statistical method to compare several dose calculation systems. The various analyses lead to the conclusion that AXB handled more accurately most of the situations investigated in heterogeneous media.
实验设计（DoE）提供了一种方法，可以在有限的试验次数下揭示输入值对测量输出的影响。本研究的目的是描述如何使用 DoE 来评估几种剂量计算系统在不均匀介质中的性能，包括铅笔束（PB）、各向异性解析算法（AAA）、Acuros XB（AXB）、蒙特卡罗（MC）和Collapsed Cone Volume（CCV）等算法。
本研究使用 CIRS 模型 002LFC IMRT 胸部体模进行，该体模在肺部内部具有水等效不均匀性。计算的剂量分布与 Gafchromic® EBT3 胶片测量结果进行比较。使用 DoE 选择射束配置，以同时研究五个参数（能量、准直器角度、机架角度、X 和 Y 准直器）的影响，并优化实验次数。对整个照射场和不同感兴趣区域（肿瘤、肿瘤阴影和肺部）进行方差分析。
DoE 能够量化和确定有统计学意义的因素，从而对肺部情况下的剂量计算系统进行评估。由此产生的评分可以如下所示（从最好到最差）：AXB_D、CCV、AXB_D、XVMC_D、XVMC_D、AAA 和最后 PB。在肿瘤和阴影区域特别观察到算法之间的差异。
DoE 是一种强大的统计方法，可以比较几种剂量计算系统。各种分析得出的结论是，AXB 在不均匀介质中研究的大多数情况下更准确地处理了大部分情况。
