加速器一年QUICKCHECK检测结果与评价

The Results and Evaluation of the Quick Check Examination on the Linear Accelerator in One Year

目的对加速器射野参数一年的QUICKCHECK结果进行统计和分析,评估加速器射野中心轴剂量、平坦度、对称性、射线质、剂量率的一致性。方法 2012年2月至2013年2月间,加速器正常运行216天,故障47天。利用QUICKCHECK共对加速器共进行216次检测,检测的参数包括中心轴剂量、平坦度、对称性(G/T方向和L/R方向)、射线质、剂量率。对检测的数据进行统计和分析,评估加速器的稳定性。结果对于10 cm×10 cm射野,中心轴剂量为(100±2.3)MU,有11次(5.09%)检测结果超过2%。平坦度检测值为(100±2.6)%,有4次(1.85%)超过2%。对称性(G/T方向)检测值为(100±1.4)%。对称性(L/R方向)检测值为100±2.7%,有4次(1.85%)超过2%。射线质检测值为(100±2.79)%,有3次(1.39%)超过2%。剂量率检测值为(300±11.2)MU/min。对于20 cm×20 cm射野,中心轴剂量为(100±2.1)MU,有11次(5.09%)检测结果超过2%。平坦度检测结果为(100±1.2)%。对称性(G/T方向)为(100±0.27)%,对称性(L/R方向)为(100±1.27)%,射线质为(100±0.35)%。结论中心轴剂量合格率为94.91%,平坦度合格率为98.15%,对称性合格率为100%,射线质合格率为100%,剂量率合格率为100%。除中心轴剂量外,加速器各项参数的一致性合格率都在98%以上,具有很好的稳定性。

Objective To collect data about the QUICK CHECK on a linear accelerator＇ s field parameters, analyze the results, and evaluate the consistency of central axis dose, the flatness, symmetry, radiation quality and dose rate of the ac celerator＇ s fields. Methods During February 2012 and February 2013, the accelerator worked normally for 216 days and had breakdown for 47 days. We utilized QUICK CHECK to examine the two fields of 10 cmx 10 cm and 20 cm x 20cm and used the check results as a standard for following detection. We used QUICK CHECK to examine the linear accelerator for 216 times. Detected parameters included central axis dose, flatness, symmetry （along directions of （ gun - target） G/T and L/R （left -right） ） , radiation quality and dose rate. We collected and analyzed the detection data, and then evaluated the stability of the accelerator. Results For the field of 10 cm x 10 cm, the central axis dose was （ 100 ± 2.3） MU, and detected results exceeded 2% for 11 times （5.09%）. The detection value of flatness was （ 100 ± 2.6） % , and the results exceeded 2% for d times （ 1.85% ）. The detection value of symmetry （direction of G/T） was （ 100 ± 1.4） % , the value of symmetry （ direction of L/R） was （ 100 ± 2.7 ） % , and 4 （ 1.85% ） of the results exceeded 2%. The detection value of radiation quality was （ 100± 2.79） % , and exceeded 2% for 3 times （ 1.39% ）. The detection value of dose rate was 300 ±11.2 MU/min. For the field of 20 cm x 20 cm, the central axis dose was （ 100 ± 2.1 ） MU, and detected results exceeded 2% for 11 times （5.09%）. The detection value of flatness was （ 100± 1.2） %. The value of symmetry （ direction of G/T） was （ 100 ± 0.27 ） % , the one of symmetry （ direction of L/R） was （ 100± 1.27 ） %, radiation quality （ l00 ± 0. 35% ）. Conclusion The qualified rate of central axis dose was 94.91% , flatness 98.15% , symmetry 100% , radiation quality 100% and dose rate 100%. Except for the central axis dose, the qualified rates of consistency of the parameters were all above 98%. Therefore the accelerator＇ s sta bility was excellent.