An international calibration of Kerma-Area Product meters for patient dose optimisation study

The results of international calibration of Kerma Area Product (KAP) meters for European SENTINEL survey on patient dose optimisation of cardiac and interventional radiology practice are presented. Twelve countries were involved in the study. An investigation was conduced on 25 KAP meters fitted to undercouch X-ray tubes; 13 KAP meters were installed on cardiac units and the remaining 12 on interventional ones. The simplified calibration method has been applied, consisting of KAP estimation by multiplying the air kerma at the centre of the X-ray field by the irradiated area. The obtained values of calibration factors range from 0.4 to 0.9 and from 0.4 to 0.8 for KAP meters installed on cardiac and interventional units, respectively. They account also for table and mattress attenuation. For air kerma assessment, measurements with thermoluminescent dosemeters have been applied and when possible compared against an additional reference dosemeter. As the result of the investigation, the importance of calibration of KAP meters in clinical conditions that include mattress and table attenuation has been recognised.