QuickCheck检测加速器的能力测试与评估

目的：在改变测量条件和标准条件的情况下进行测量，对比测量结果，检测QuickCheck的性能，为加速器的晨检及检测结果判读提供依据。方法：通过改变输出剂量、射野大小、SSD、准直器角度和机架角，评估QuickCheck的检测能力。QuickCheck检测的射野参数与三维水箱等测量进行对比。结果：输出剂量增大1 cGy或减小6 cGy，射野改变≥0.2 cm；SSD减小2 cm或增大1 cm，准直器旋转≥2 o，机架角旋转≥6 o，检测结果超过阈值。与三维水箱测量的结果相比，平坦度、对称性（G/T）和（L/R）及剂量率分别相差3.84%、0.67%、0.47%，1.2 MU/min。结论：QuickCheck在检测输出剂量、射野大小、准直器角度、平坦度、对称性及剂量率方面准确度很高，能够满足日常加速器质量保证的需要。在检测SSD、机架角偏差方面能力较弱。

Research on the capability test and evaluation of the QuickCheck＇s accelerator

Objective：To give the test in cases of changing the conditions of measurement and reference value, compare the test results, and detect the capacity of QuickCheck, so as to offer reference for the daily morning check of accelerator and the evaluation of test results. Methods：Change the output dose, field size, SSD, angle of collimator and gantry angle of the accelerator, and then evaluate QuickCheck’s capacity of monitoring accelerator accordingly. Compare the field parameters measured by QuickCheck with the data from the 3D water tank. Results：When the output dose was 1 cGy higher than the reference value or 6 cGy lower than it, the field size expanded or contracted more than 2 cm simutaneouly, SSD was 2 cm higher or 1 cm lower than reference value, the collimator rotated more than 2 °, the gantry angle rotated more than 6 °, and then the test results of QuickCheck surpassed threshold. Comparing the measuring results of QuickCheck with 3D water tank, the difference between the flatness of the two was 3.84%, symmetry （G/T） 0.67%, symmetry （L/R） 0.47%and dose rate 1.2 MU/min. Conclusion：QuickCheck is rather accurate in testing the output dose, field size, angle of collimator, flatness, symmetry and dose rate, so it could meet the requirement of accelerator’s daily QA. However, its capability is relatively poor on examining SSD and the deviation of gantry angle.