Real-time measurement of radiation exposure to patients during diagnostic coronary angiography and percutaneous interventional procedures

OBJECTIVES The aim of this study was to accurately assess the radiation exp osure received by patients during cardiac catheterization in a large sample representative of the current state of practice in cardiac angiography. BACKGROUND Radiation exposure to patients and laboratory staff has been rec ognized as a necessary hazard in coronary angiography. The effects on x-ray exposure of the increased complexity of coronary angiographic procedures a nd, in particular, the increasing use of coronary artery stenting, have not been adequately addressed in previous studies. METHODS X-ray exposure measurements were performed on a consecutive series of 972 patients undergoing 992 diagnostic and interventional studies in the Mayo Clinic catheterization laboratory within an eight week period in late 1997. Data were acquired from 706 diagnostic procedures and 286 interventi onal procedures using a real-time exposure measurement system to continuous ly calculate and record the exposure rate and total exposure, reflecting al l parameters relevant to the specific patient and procedure situation. RESULTS The median exposure for all 992 procedures was 41.8 mC/kg (162.1 R) ; the corresponding values for diagnostic and interventional procedures wer e 34.9 and 95.6 mC/kg, respectively (135.3 vs. 370.5 R). There were signifi cant differences in the fluoroscopy exposure time between diagnostic and in terventional procedures: 4.7 min vs. 21.0 min. Heavier patients (>83 kg) re ceived x-ray exposures at a significantly higher rate than did lighter pati ents (<83 kg) during both fluoroscopy and cine; 44.9 mC/kg/min (173.9 R/min ) vs. 27.9 mC/kg/min (108.3 R/min) for cine exposure rate and 2.3 mC/kg/min (8.8 R/min) vs. 1.5 mC/kg/min (5.8 R/min) for fluoroscopy exposure rate. CONCLUSIONS Changes in practice have led to higher values for patient x-ray radiation exposures during cardiac catheterization procedures. The real-ti me display and recording of x-ray exposure facilitates the reduction of exp osure in the catheterization laboratory. (C) 1999 by the American College o f Cardiology.