X射线空气比释动能(治疗水平)标准装置的建立

为开展X射线在治疗水平剂量率下的量值溯源与传递工作,依据IEC 60731—1997标准的要求,建立了管电压为10~250 kV、剂量率范围为1.0×10^-3~10 Gy/h的X射线空气比释动能(治疗水平)标准装置。其中10~60 kV X射线空气比释动能(治疗水平)标准装置在1.0 m处非均匀性小于1%的辐射野为ø60 mm,散射对辐射场贡献小于1.2 %,在距离放射源1~5 m范围内反平方律在2.5 %内符合,使用标准电离室测得装置的稳定性为1.8％、重复性为0.1％。60~250 kV X射线空气比释动能(治疗水平)标准装置在1.0 m处非均匀性小于1%的辐射野为ø80 mm,散射对辐射场贡献小于1.2 %,在距离放射源1~5 m范围内反平方律在1.5 %内符合,使用标准电离室测得装置的稳定性为1.7％、重复性为0.03％。标准装置辐射场空气比释动能率的相对扩展不确定度为3.0％ (k=2),经测量,装置的各项性能指标均满足治疗水平剂量检测仪器的检定/校准要求。

Establishment of X-ray air kerma (radiotherapy level) standard device

In order to carry out the work of traceability and transmission of X-rays at the dose rate of radiotherapy, according to IEC 60731—1997 standard, a standard device of X-rays air kerma (radiotherapy) with tube voltage of 10-250 kV and dose rate range of 1.0×10^-3 -10 Gy/h was established. Of which 10-60 kV X-ray air kerma (radiotherapy) standard device at 1.0 m heterogeneity is less than 1% of the radiation field for ø60 mm, scattering contribution to radiation field is less than 1.2%, from the source 1 m-5 m within the inverse square law at 2.5%, within the scope of using standard ionization chamber stability of the measurement device is 1.8%, repeatability is 0.1%. 60-250 kV X-ray air kerma (radiotherapy) standard device at 1.0 m heterogeneity is less than 1% of the radiation field for ø80 mm, scattering contribution to radiation field is less than 1.2%, from the source 1 m~5 m within the inverse square law at 1.5%, within the scope of using standard ionization chamber stability of the measurement device is 1.7%, repeatability is 0.03%. The relative extended uncertainty of the radiation field air kerma (rare) of the standard device was 3.0% (k=2). The performance indexes of the measured device all met the verification/calibration requirements of the therapeutic level dose detection instrument.