Brooks Fre'Etta M D, Glenn Mallory C, Hernandez Victor, Saez Jordi, Pollard-Larkin Julianne M, Peterson Christine B, Howell Rebecca M, Nelson Christopher L, Clark Catharine H, Kry Stephen F
University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas; Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas.
Department of Medical Physics, Hospital Sant Joan de Reus, Institut d'Investigació Sanitària Pere Virgili, Tarragona, Spain.
Int J Radiat Oncol Biol Phys. 2025 Mar 1;121(3):811-821. doi: 10.1016/j.ijrobp.2024.09.053. Epub 2024 Oct 2.
The Imaging Radiation Oncology Core (IROC) head and neck (H&N) phantom is used to credential institutions for intensity modulated radiation therapy delivery for all anatomic sites where delivery of modulated therapy is a primary challenge. This study evaluated how appropriate the use of this phantom is for varied clinical anatomy by evaluating how closely the IROC H&N phantom described clinical dose errors from beam modeling compared with various anatomic sites.
The multileaf collimator (MLC) offset, transmission, percent depth dose, and 7 additional beam modeling parameters for a Varian accelerator were modified in RayStation to match community data at the 2.5th, 25th, 50th, 75th, and 97.5th percentile levels. Modifications were evaluated on 25 H&N phantom cases and 25 clinical cases (H&N, prostate, lung, mesothelioma, and brain), generating 2000 plan perturbations. Differences in mean dose delivered to clinical target volumes and maximum dose to organs at risk were compared between phantom and clinical plans to assess the relationship between dose deviations in phantom versus clinical target volumes and as a function of 18 different complexity metrics.
Perturbations to MLC offset and transmission parameters demonstrated the greatest impact on dose accuracy for phantom and clinical plans (for all anatomic sites). The phantom demonstrated equivalent or greater sensitivity to these parameter perturbations compared with clinical sites, largely aligning with treatment complexity. The mean MLC gap best described the impact of errors in treatment planning system beam modeling parameters in phantom plans and clinical plans from various anatomic sites.
When compared across various anatomic sites, the IROC H&N credentialing phantom exhibited similar or greater sensitivity to errors in the treatment planning system. As such, it is a suitable surrogate device for assessing institutional performance across various anatomic sites. If an institution successfully irradiates the phantom, that result confers confidence that intensity modulated radiation therapy to a wide range of anatomic sites can be successfully delivered by the institution.
影像放射肿瘤学核心（IROC）头颈部（H&N）体模用于对机构进行强度调制放射治疗（IMRT）的资格认证，适用于所有调制治疗实施面临主要挑战的解剖部位。本研究通过评估IROC H&N体模与不同解剖部位相比，在描述束流建模的临床剂量误差方面的吻合程度，来评估该体模对不同临床解剖结构的适用性。
在RayStation中修改了瓦里安加速器的多叶准直器（MLC）偏移、透射率、百分深度剂量以及7个额外的束流建模参数，以匹配第2.5、25、50、75和97.5百分位数水平的群体数据。在25例H&N体模病例和25例临床病例（H&N、前列腺、肺、间皮瘤和脑）上评估这些修改，产生2000个计划扰动。比较体模计划和临床计划中输送至临床靶区的平均剂量以及危及器官的最大剂量差异，以评估体模与临床靶区剂量偏差之间的关系，并作为18种不同复杂性指标的函数。
对MLC偏移和透射率参数的扰动对体模和临床计划（所有解剖部位）的剂量准确性影响最大。与临床部位相比，体模对这些参数扰动表现出同等或更高的敏感性，这在很大程度上与治疗复杂性相符。平均MLC间隙最能描述不同解剖部位的体模计划和临床计划中治疗计划系统束流建模参数误差的影响。
与不同解剖部位相比，IROC H&N资格认证体模对治疗计划系统中的误差表现出相似或更高的敏感性。因此，它是评估不同解剖部位机构性能的合适替代设备。如果一个机构成功照射了该体模，那么这一结果让人相信该机构能够成功地对广泛的解剖部位实施强度调制放射治疗。
