TrueBeam直线加速器的机器性能检查应用程序评估
Evaluation of the Machine Performance Check application for TrueBeam Linac.
作者信息
Clivio Alessandro, Vanetti Eugenio, Rose Steven, Nicolini Giorgia, Belosi Maria F, Cozzi Luca, Baltes Christof, Fogliata Antonella
机构信息
IOSI, Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona, 6504, Switzerland.
Varian Medical Systems Imaging Laboratory, Baden-Dättwil, Switzerland.
出版信息
Radiat Oncol. 2015 Apr 21;10:97. doi: 10.1186/s13014-015-0381-0.
BACKGROUND
Machine Performance Check (MPC) is an application to verify geometry and beam performances of TrueBeam Linacs, through automated checks based on their kV-MV imaging systems. In this study, preliminary tests with MPC were analyzed using all photon beam energies of our TrueBeam, comparing whenever possible with external independent checks.
METHODS
Data acquisition comprises a series of 39 images (12 with kV and 27 with MV detector) acquired at predefined positions without and with the IsoCal phantom in the beam, and with particular MLC pattern settings. MPC performs geometric and dosimetric checks. The geometric checks intend to test the treatment isocenter size and its coincidence with imaging devices, the positioning accuracy of the imaging systems, the collimator, the gantry, the jaws, the MLC leaves and the couch position. The dosimetric checks: refer to a reference MV image and give the beam output, uniformity and center change relative to the reference. MPC data were acquired during 10 repetitions on different consecutive days. Alternative independent checks were performed. Geometric: routine mechanical tests, Winston-Lutz test for treatment isocenter radius. Dosimetric: the 2D array StarCheck (PTW) was used just after the MPC data acquisition.
RESULTS
Results were analyzed for 6, 10, 15 MV flattened, and 6, 10 MV FFF beams. Geometric checks: treatment isocenter was between 0.31 ± 0.01 mm and 0.42 ± 0.02 mm with MPC, compared to 0.27 ± 0.01 mm averaged on all energies with the Winston-Lutz test. Coincidence of kV and MV imaging isocenters was within 0.36 ± 0.0 and 0.43 ± 0.06 mm, respectively (0.4 ± 0.1 mm with external tests). Positioning accuracy of MLC was within 0.5 mm; accuracy of jaws was 0.04 ± 0.02, 0.10 ± 0.05, -1.01 ± 0.03, 0.92 ± 0.04 mm for X1, X2, Y1, Y2 jaws, respectively, with MPC. Dosimetric tests: the output stability relative to the baseline was in average 0.15 ± 0.07% for MPC to compare with 0.3 ± 0.2% with the independent measurement.
CONCLUSIONS
MPC proved to be a reliable, fast and easy to use method for checking the machine performances on both geometric and dosimetric aspects.
背景
机器性能检查（MPC）是一种通过基于TrueBeam直线加速器的kV-MV成像系统进行自动检查来验证其几何和射束性能的应用程序。在本研究中，使用我们TrueBeam的所有光子束能量对MPC的初步测试进行了分析，并尽可能与外部独立检查进行比较。
方法
数据采集包括在预定义位置采集的一系列39张图像（12张kV图像和27张MV探测器图像），束中有无IsoCal体模以及特定的多叶准直器（MLC）模式设置。MPC执行几何和剂量学检查。几何检查旨在测试治疗等中心尺寸及其与成像设备的重合度、成像系统、准直器、机架、钳口、MLC叶片和治疗床位置的定位精度。剂量学检查：参考一张MV参考图像，并给出相对于参考的射束输出、均匀性和中心变化。MPC数据在不同连续日期进行了10次重复采集。进行了替代独立检查。几何方面：常规机械测试、用于治疗等中心半径的温斯顿-卢茨测试。剂量学方面：在MPC数据采集后立即使用二维阵列StarCheck（PTW）。
结果
对6、10、15 MV扁平束以及6、10 MV FFF束的结果进行了分析。几何检查：使用MPC时，治疗等中心在0.31±0.01毫米至0.42±0.02毫米之间，而通过温斯顿-卢茨测试在所有能量下平均为0.27±0.01毫米。kV和MV成像等中心的重合度分别在0.36±0.0和0.43±0.06毫米内（外部测试为0.4±0.1毫米）。MLC的定位精度在0.5毫米内；使用MPC时，X1、X2、Y1、Y2钳口的精度分别为0.04±0.02、0.10±0.05、-1.01±0.03、0.92±0.04毫米。剂量学测试：相对于基线的输出稳定性，MPC平均为0.15±0.07%，而独立测量为0.3±0.2%。
结论
MPC被证明是一种在几何和剂量学方面检查机器性能的可靠、快速且易于使用的方法。
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