Updating national diagnostic reference levels for interventional cardiology and methodological aspects.

The aim of this study is to propose national diagnostic reference levels (DRL) for updating in the field of interventional cardiology and to include technical details to help plan optimization. Medical physics experts and interventional cardiologists from 14 hospitals provided patient dose indicators from coronary angiography and percutaneous coronary interventions. Information about X-ray system dose settings and image quality was also provided. The dose values from 30,024 procedures and 26 interventional laboratories were recorded. The national DRLs proposed for coronary angiography and percutaneous coronary interventions were respectively 39 and 78 Gy·cm for air kerma area product (P), 530 and 1300 mGy for air kerma at reference point (K), 6.7 and 15 min of fluoroscopy time and 760 and 1300 cine images. 36% of the KAP meters required correction factors from 10 to 35%. The dose management systems should allow these corrections to be included automatically. The dose per image in cine in reference conditions differed in a factor of 5.5. Including X-ray system dose settings in the methodology provides an insight into the differences between hospitals. The DRLs proposed for Spain in this work were similar to those proposed in the last European survey. The poor correlation between X-ray systems dose settings and patient dose indicators highlights that other factors such as operation protocols and complexity may have more impact in patient dose indicators, which allows a wide margin for optimization. Dose reduction technology together with appropriate training programs will be determinant in the future reduction of patient dose indicators.