An SSDLs calibration method for the kerma-area product meter

The kerma-area product meter (KAP meter) is mainly used for quality assurance in medical imaging research, providing dose quality assessment or dose monitoring for patients. It can be calibrated either in the laboratory or on-site. The purpose of this study is to propose a method for calibrating the KAP meter using a plane-parallel transmission ionization chamber in the SSDLs. In the range of 50 kV–150 kV, under RQR (standard radiation qualities) and RQR additional filtering conditions of the KAP meter, the correction factor $N_Q^m$ of the transmission ionization chamber is calculated to select two types of KAP meters for the calibration of the transmitted beam. The collimators used to limit the size of the radiation field are respectively 50.07 mm in length, 30.03 mm in length, and 20.05 mm in radius. This method, with uncertainty not exceeding 3.0% while improving calibration efficiency, can replace the unit-specific correction of the laboratory method (Toroi et al., 2008).