Huang Jianghua, Hu Jinyan, Lu Huanping, Liu Shijie, Gong Fengying, Wu Xiuxiu, Liu Yimin, Shi Juntian
Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, China; Department of Radiation Oncology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120, China.
Department of Oncology, Longhua District People's Hospital, Shenzhen, Guangdong Province, 518109, China.
Appl Radiat Isot. 2023 Feb;192:110567. doi: 10.1016/j.apradiso.2022.110567. Epub 2022 Nov 25.
To investigate the error detectability limitations of an EPID-based 3D in vivo dosimetry verification system for lung stereotactic body radiation therapy (SBRT).
Thirty errors were intentionally introduced, consisting of dynamic and constant machine errors, to simulate the possible errors that may occur during delivery. The dynamic errors included errors in the output, gantry angle and MLC positions related to gantry inertial and gravitational effects, while the constant errors included errors in the collimator angle, jaw positions, central leaf positions, setup shift and thickness to simulate patient weight loss. These error plans were delivered to a CIRS phantom using the SBRT technique for lung cancer. Following irradiation of these error plans, the dose distribution was reconstructed using iViewDose™ and compared with the no error plan.
All errors caused by the central leaf positions, dynamic MLC errors, Jaw inwards movements, setup shifts and patient anatomical changes were successfully detected. However, dynamic gantry angle and collimator angle errors were not detected in the lung case due to the rotation-symmetric target shape. The results showed that the γ and γ indicators can detect 13 (81.3%) and 14 (87.5%) of the 16 errors respectively without including the gantry angle error, collimator angle error and output error.
In summary, iViewDose™ is an appropriate approach for detecting most types of clinical errors for lung SBRT. However, the phantom results also showed some detectability limitations of the system in terms of dynamic gantry angle and constant collimator angle errors.
研究基于电子射野影像装置（EPID）的三维体内剂量验证系统在肺部立体定向体部放射治疗（SBRT）中的误差可检测性限制。
故意引入30种误差，包括动态和恒定的机器误差，以模拟治疗过程中可能出现的误差。动态误差包括与机架惯性和重力效应相关的输出、机架角度和多叶准直器（MLC）位置的误差，而恒定误差包括准直器角度、光阑位置、中心叶片位置、摆位偏移和厚度的误差，以模拟患者体重减轻。使用肺癌SBRT技术将这些误差计划照射到CIRS体模上。照射这些误差计划后，使用iViewDose™重建剂量分布，并与无误差计划进行比较。
由中心叶片位置、动态MLC误差、光阑向内移动、摆位偏移和患者解剖结构变化引起的所有误差均被成功检测到。然而，由于靶区形状的旋转对称性，在肺部病例中未检测到动态机架角度和准直器角度误差。结果表明，在不包括机架角度误差、准直器角度误差和输出误差的情况下，γ和γ指标分别可以检测出16种误差中的13种（81.3%）和14种（87.5%）。
总之，iViewDose™是检测肺部SBRT大多数类型临床误差的合适方法。然而，体模结果也显示了该系统在动态机架角度和恒定准直器角度误差方面的一些可检测性限制。
