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 exposure 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 recognized as a necessary hazard in coronary angiography. The effects on x-ray exposure of the increased complexity of coronary angiographic procedures and, 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 interventional procedures using a real-time exposure measurement system to continuously calculate and record the exposure rate and total exposure, reflecting all 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 were 34.9 and 95.6 mC/kg, respectively (135.3 vs. 370.5 R). There were significant differences in the fluoroscopy exposure time between diagnostic and interventional procedures: 4.7 min vs. 21.0 min. Heavier patients (>83 kg) received x-ray exposures at a significantly higher rate than did lighter patients (<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-time display and recording of x-ray exposure facilitates the reduction of exposure in the catheterization laboratory.