基于IAEA398号报告进行直线加速器输出量校准的实践与探索

Practice and explore of dose calibration for linear accelerator based on IAEA398 report

目的:基于国际原子能机构(IAEA)398号报告,实践和探索基于水模体吸收剂量校准因子N_W的直线加速器输出量校准。方法:测量每档光子线和电子线辐射质,根据辐射质通过查找IAEA398号报告中的图表,计算出我科加速器各档光子线和电子线K_Q因子、校准深度,并测量校准深度处的PDD值。结果:按照IAEA398号报告,对于光子线6和10 MV,其射线质分别为0.681和0.732,其测量深度均为10 cm,K_Q分别为0.990和0.982,与对应的K_(Q,277)分别相差-0.81%和-0.81%。对于电子线,包括6、8、10、12、15、18 Me V,其射线质分别为2.481、3.225、3.964、4.747、5.959、7.234 cm,测量深度分别为1.39、1.84、2.28、2.75、3.48、4.24 cm,K_Q分别为0.937、0.928、0.920、0.914、0.904、0.897,与对应的K_(Q,277)分别相差0.60%、0.97%、0.43%、0.66%、0.11%、-0.45%。结论:相比IAEA277号报告,IAEA398号报告在实践过程中更直观,更易操作,两个报告剂量标定结果差异小于1%。

Objective To practice and explore the dose calibration of linear acceleration based on the absorbed dose calibration factor NW of water phantom, according to International Atomic Energy Agency（IAEA） 398 report. Methods The radiation qualities of each photon beam and electron beam were measured. By looking up tables in IAEA398 report based on beam quality, the KQfactor, calibration depth of each photon beam, and electron beam of the linear accelerator in the Department of Radiotherapy, Shanghai Eastern Hepatobiliary Surgery Hospital, were calculated, and the PDD value at calibration depth were measured. Results According to IAEA398 report, for photon beams of 6 and 10 MV, the radiation quality was 0.681 and 0.732,respectively; the measured calibration depth was 10 cm for both; KQwas 0.990 and 0.982, respectively; the difference between KQand corresponding KQ,277was-0.81% and-0.81%, respectively. For electron beams of 6, 8, 10, 12, 15 and 18 Me V, the radiation quality was 2.481, 3.225, 3.964, 4.747, 5.959 and 7.234 cm, respectively; the measured calibration depth was 1.39,1.84, 2.28, 2.75, 3.48 and 4.24 cm, respectively; KQwas 0.937, 0.928, 0.920, 0.914, 0.904 and 0.897, respectively; the difference between KQand corresponding KQ,277 was 0.60%, 0.97%, 0.43%, 0.66%, 0.11% and-0.45%, respectively.Conclusion Compared to IAEA277 report, IAEA398 report is more intuitive and practicable. The difference in dose calibration between IAEA277 report and IAEA398 report is less than 1%.