New York-Presbyterian/Columbia University Irving Medical Center (NYP/CUIMC), New York, NY, USA.
Rider University, Lawrenceville, NJ, USA.
J Appl Clin Med Phys. 2021 May;22(5):24-35. doi: 10.1002/acm2.13237. Epub 2021 Mar 31.
Two-dimensional (2D) IMRT QA has been widely performed in Radiation Oncology clinic. However, concerns regarding its sensitivity in detecting delivery errors and its clinical meaning have been raised in publications. In this study, a robust methodology of three-dimensional (3D) IMRT QA using fiducial registration and structure-mapping was proposed to acquire organ-specific dose information.
Computed tomography (CT) markers were placed on the PRESAGE dosimeter as fiducials before CT simulation. Subsequently, the images were transferred to the treatment planning system to create a verification plan for the examined treatment plan. Patient's CT images were registered to the CT images of the dosimeter for structure mapping according to the positions of the fiducials. After irradiation, the 3D dose distribution was read-out by an optical-CT (OCT) scanner with fiducials shown on the OCT dose images. An automatic localization algorithm was developed in MATLAB to register the markers in the OCT images to those in the CT images of the dosimeter. SlicerRT was used to show and analyze the results. Fiducial registration error was acquired by measuring the discrepancies in 20 fiducial registrations, and thus the fiducial localization error and target registration error (TRE) was estimated.
Dosimetry comparison between the calculated and measured dose distribution in various forms were presented, including 2D isodose lines comparison, 3D isodose surfaces with patient's anatomical structures, 2D and 3D gamma index, dose volume histogram and 3D view of gamma failing points. From the analysis of 20 fiducial registrations, fiducial registration error was measured to be 0.62 mm and fiducial localization error was calculated to be 0.44 mm. Target registration uncertainty of the proposed methodology was estimated to be within 0.3 mm in the area of dose measurement.
This study proposed a robust methodology of 3D measurement-based IMRT QA for organ-specific dose comparison and demonstrated its clinical feasibility.
二维（2D）调强放射治疗（IMRT）质量保证（QA）已在放射肿瘤学临床中广泛应用。然而，一些研究报告中对其检测治疗误差的敏感性及其临床意义提出了担忧。本研究提出了一种使用基准点注册和结构映射的三维（3D）调强放射治疗 QA 稳健方法，以获取器官特异性剂量信息。
在 CT 模拟前，将 CT 标记物放置在 PRESAGE 剂量计上作为基准点。随后，将图像传输到治疗计划系统，为所检查的治疗计划创建验证计划。根据基准点的位置，将患者的 CT 图像与剂量计的 CT 图像进行配准，以进行结构映射。照射后，使用带有基准点的光学 CT（OCT）扫描仪读取 3D 剂量分布。在 MATLAB 中开发了一种自动定位算法，用于将 OCT 图像中的标记与剂量计的 CT 图像中的标记进行配准。使用 SlicerRT 显示和分析结果。通过测量 20 次基准点配准的差异来获取基准点配准误差，从而估计基准点定位误差和靶区注册误差（TRE）。
呈现了各种形式的计算剂量分布与测量剂量分布的比较，包括 2D 等剂量线比较、带有患者解剖结构的 3D 等剂量曲面、2D 和 3D 伽马指数、剂量体积直方图和伽马失败点的 3D 视图。通过对 20 次基准点配准的分析，测量得到的基准点配准误差为 0.62mm，计算得到的基准点定位误差为 0.44mm。该方法的靶区注册不确定性估计在剂量测量区域内为 0.3mm 以内。
本研究提出了一种用于器官特异性剂量比较的稳健的基于 3D 测量的调强放射治疗 QA 方法，并证明了其临床可行性。
