Proposal of reference levels for cardiac interventional procedures. An European Coordination Action

Interventional cardiology is a medical specialty widely known to deliver high radiation dose to patients, who may receive, in some complex cases, skin doses over the threshold for deterministic effects. Because several studies have demonstrated large variability in delivered doses, European SENTINEL consortium has carried out a patient dose survey to propose regional Reference Levels (RL) as a tool to reduce dose variability and aid in the optimisation of radiation protection. The survey, performed in cardiac centres from 9 European countries, investigated doses in selected cardiac procedures: coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA) and electrophysiology, collecting data on near 2,000 procedures. All examined doses, air kerma area product (KAP) and cumulative dose (CD) at the Interventional Reference Point, or dose analogues, fluoroscopy time and number of acquired images, exhibit a large variability. The examinations have been pooled and RL assessed as the 75° percentile of distributions. Proposed European RL for kerma-area product (KAP) are: 45, 85 and 35 Gycm2, for fluoroscopy time: 6.5, 15.5 and 21 min, respectively for CA, PTCA and diagnostic electrophysiology procedures. Because equipment performance is one of the factors contributing to patient dose variability, RL for air kerma for fluoroscopy and image acquisition measured (in low dose modes) at the entrance of a 20 cm PMMA phantom, are also proposed: 13 Gy/min and 100 μGy/image respectively. The study confirms a large variability of patient doses across Europe and the need of a set of European RL as a tool for the optimisation of radiation protection for patients. The complexity of the procedures should be introduced in the future to refine RL in fluoroscopy guided procedures (SENTINEL EURATOM Research contract No. 012909).