Malusek A, Sandborg M, Carlsson G Alm
Medical Radiation Physics, Department of Medical and Health Sciences and Center for Medical Image Science and Visualisation, Linköping University, Linköping SE 58185, Sweden
Medical Radiation Physics, Department of Medical and Health Sciences and Center for Medical Image Science and Visualisation, Linköping University, Linköping SE 58185, Sweden.
Radiat Prot Dosimetry. 2016 Jun;169(1-4):353-9. doi: 10.1093/rpd/ncv524. Epub 2016 Jan 7.
Modern X-ray units register the air kerma-area product, PKA, with a built-in KAP meter. Some KAP meters show an energy-dependent bias comparable with the maximum uncertainty articulated by the IEC (25 %), adversely affecting dose-optimisation processes. To correct for the bias, a reference KAP meter calibrated at a standards laboratory and two calibration methods described here can be used to achieve an uncertainty of <7 % as recommended by IAEA. A computational model of the reference KAP meter is used to calculate beam quality correction factors for transfer of the calibration coefficient at the standards laboratory, Q0, to any beam quality, Q, in the clinic. Alternatively, beam quality corrections are measured with an energy-independent dosemeter via a reference beam quality in the clinic, Q1, to beam quality, Q Biases up to 35 % of built-in KAP meter readings were noted. Energy-dependent calibration factors are needed for unbiased PKA Accurate KAP meter calibration as a prerequisite for optimisation in projection radiography.
现代X射线设备通过内置的空气比释动能面积乘积（PKA）测量仪来记录空气比释动能面积乘积。一些PKA测量仪显示出与国际电工委员会（IEC）明确的最大不确定度（25%）相当的能量依赖性偏差，这对剂量优化过程产生了不利影响。为了校正这种偏差，可以使用在标准实验室校准的参考PKA测量仪以及这里描述的两种校准方法，以达到国际原子能机构（IAEA）推荐的小于7%的不确定度。参考PKA测量仪的计算模型用于计算在标准实验室校准系数Q0转换到临床中任何射束质Q时的射束质校正因子。或者，通过临床中的参考射束质Q1到射束质Q，使用与能量无关的剂量仪测量射束质校正。注意到内置PKA测量仪读数的偏差高达35%。无偏差的PKA需要能量依赖性校准因子。准确的PKA测量仪校准是投影放射成像优化的前提条件。
