University of Florida Proton Therapy Institute, Jacksonville, FL 32206, USA.
J Appl Clin Med Phys. 2013 Jan 7;14(1):3949. doi: 10.1120/jacmp.v14i1.3949.
One of the most important aspects of quality assurance (QA) in radiation therapy is redundancy of patient treatment dose calculation. This work is focused on the patient-specific time and 3D dose treatment plan verification for stereotactic radiosurgery using Leksell Gamma Knife Perfexion (LGK PFX). The virtual model of LGK PFX was developed in MATLAB, based on the physical dimensions provided by the manufacturer. The ring-specific linear attenuation coefficients (LAC) and output factors (OFs) reported by the manufacturer were replaced by the measurement-based collimator size-specific OFs and a single LAC = 0.0065 mm-1. Calculation depths for each LGK PFX shot were obtained by ray-tracing technique, and the dose calculation formalism was similar to the one used by GammaPlan treatment planning software versions 8 and 9. The architecture of the QA process was based on the in-house online database search of the LGK PFX database search for plan-specific information. A series of QA phantom plans was examined to verify geometric and dosimetric accuracy of the software. The accuracy of the QA process was further evaluated through evaluation of a series of patient plans. The shot time/focus point dose verification for each shot took less than 1 sec/shot with full 3D isodose verification taking about 30 sec/shot on a desktop PC. GammaPlan database access time took less than 0.05 sec. The geometric accuracy (location of the point of maximum dose) of the phantom and patient plan was dependent on the resolution of the original dose matrix and was of the order of 1 dose element. Dosimetric accuracy of the independently calculated phantom and patient point (focus) doses was within 3.5% from the GammaPlan, with the mean = 2.3% and SD= 1.1%. The process for independent pretreatment patient-specific Gamma Knife Perfexion time and dose verification was created and validated.
放射治疗质量保证（QA）最重要的方面之一是患者治疗剂量计算的冗余性。这项工作专注于使用 Leksell Gamma Knife Perfexion（LGK PFX）进行立体定向放射外科的患者特定时间和 3D 剂量治疗计划验证。LGK PFX 的虚拟模型是在 MATLAB 中开发的，基于制造商提供的物理尺寸。制造商报告的环形特定线性衰减系数（LAC）和输出因子（OF）被基于测量的准直器尺寸特定 OF 和单个 LAC = 0.0065 mm-1 取代。每个 LGK PFX 射击的计算深度是通过射线追踪技术获得的，剂量计算形式与 GammaPlan 治疗计划软件版本 8 和 9 中使用的类似。QA 过程的体系结构基于内部在线数据库搜索 LGK PFX 数据库以搜索特定于计划的信息。检查了一系列 QA 体模计划，以验证软件的几何和剂量准确性。通过评估一系列患者计划进一步评估 QA 过程的准确性。对于每个射击，射击时间/焦点剂量验证需要不到 1 秒/射击，而完整的 3D 等剂量验证需要大约 30 秒/射击在台式 PC 上。GammaPlan 数据库访问时间不到 0.05 秒。体模和患者计划的几何精度（最大剂量点的位置）取决于原始剂量矩阵的分辨率，并且在 1 个剂量元素的顺序。独立计算的体模和患者点（焦点）剂量的剂量准确性与 GammaPlan 相差 3.5％以内，平均值= 2.3％，标准偏差= 1.1％。创建并验证了独立的预处理患者特定的伽玛刀 Perfexion 时间和剂量验证过程。
