Linsalata Stefania, Pensavalle Jake H, Perrone Franco, Barca Patrizio, Di Martino Fabio, Paiar Fabiola, Traino Antonio C
U.O. Fisica Sanitaria, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy.
Scuola di Specializzazione in Fisica Medica, Università degli Studi di Pisa, Pisa, Italy.
J Appl Clin Med Phys. 2025 Aug;26(8):e70167. doi: 10.1002/acm2.70167.
Despite the rapid growth in the clinical practice, no specific recommendations on pre-treatment patient-specific quality assurance of volumetric modulated arc therapy-based stereotactic body radiation therapy plans have been established.
In this contest, the study aims to identify optimal gamma analysis criteria and thresholds for the Sun Nuclear ArcCHECK and SRS MapCHECK arrays.
Twenty SBRT plans were delivered on both devices per plan and field-by-field. The measurements were compared with calculations and Gamma Passing Rates (GPRs), obtained using global normalization in absolute dose and 10% threshold, with six different Dose Difference (DD) / Distance To Agreement (DTA) criteria stricter than those universally suggested by the Report of the AAPM Task Group No. 218, were recorded. Receiver Operating Characteristics analysis was performed on GPRs while varying the threshold from 0% to 100%, the agreement between calculations and absolute dose measurements, obtained with a IBA Razor chamber at the isocenter in phantom at different levels (i.e., 1%, 2%, 3%, 4%, and 5%), being the Ground Truth. Significance of the resulting Areas Under Curve (AUCs) against the random guess was tested.
AUCs obtained with ArcCHECK are generally more significant than with SRS MapCHECK, while those measured field-by-field are more significant than per plan. Within the considered DD/DTA criteria, the most discriminative ones are device-specific, that is, 2%/2 mm or 1%/2 mm for ArcCHECK and 2%/1 mm or 1%/1 mm for SRS MapCHECK.
Our results on ArcCHECK confirm the indication of the AAPM Task Group No. 218, while for SRS MapCHECK, acceptable discriminating capabilities are possible with DTA = 1 mm, suggesting that devices with native higher spatial resolution, preferred in SBRT for the better sampling of the dose distribution, require tighter DTA.
尽管临床实践发展迅速，但尚未建立关于基于容积调强弧形治疗的立体定向体部放射治疗计划的治疗前患者特异性质量保证的具体建议。
在此背景下，本研究旨在确定适用于Sun Nuclear ArcCHECK和SRS MapCHECK阵列的最佳伽马分析标准和阈值。
每个计划在两种设备上逐野交付20个立体定向体部放射治疗计划。将测量结果与计算结果以及伽马通过率（GPR）进行比较，伽马通过率通过绝对剂量的全局归一化和10%阈值获得，记录了六种比美国医学物理学家协会第218任务组报告普遍建议的标准更严格的不同剂量差异（DD）/距离一致性（DTA）标准。在将阈值从0%变化到100%时，对伽马通过率进行了受试者操作特征分析，计算结果与在体模等中心不同水平（即1%、2%、3%、4%和5%）使用IBA Razor电离室获得绝对剂量测量值之间的一致性作为真实情况。测试了所得曲线下面积（AUC）相对于随机猜测的显著性。
使用ArcCHECK获得的AUC通常比使用SRS MapCHECK更显著，而逐野测量的AUC比按计划测量的更显著。在所考虑的DD/DTA标准中，最具区分性的标准是特定于设备的，即ArcCHECK为2%/2毫米或1%/2毫米，SRS MapCHECK为2%/1毫米或1%/1毫米。
我们关于ArcCHECK的结果证实了美国医学物理学家协会第218任务组的建议，而对于SRS MapCHECK，当DTA = 1毫米时具有可接受的区分能力，这表明在立体定向体部放射治疗中因能更好地采样剂量分布而更受青睐的具有更高固有空间分辨率的设备需要更严格的DTA。
