This study investigates the factors associated with higher doses for both single-plane and biplane procedures and establishes centre-specific 75th percentile levels.
602 patients undergoing coronary angiography in a large hospital at Sydney were recruited to the study, and causal agents for high radiation doses were investigated: gender, procedural complexity, severity of coronary artery disease, presence of coronary bypass grafts, entry approach (radial or femoral), level of operator experience; and a single-plane or a biplane imaging system was employed.
The 75th percentile levels were calculated. The results demonstrated that, for both systems, higher exposures were associated with patients who were male (p<0.001), had coronary vessel disease (p<0.001) and had a history of coronary bypass grafts (p<0.001). In addition, for biplane systems, procedural complexity (p<0.001), types of entry approach (p<0.001) and levels of operator experience (p<0.001) significantly impacted upon the dose. Biplane examinations recorded higher doses than single-plane procedures (p<0.001) and the inclusion of left-sided ventriculography contributed to the overall dose by up to 10%.
The 75th percentile levels in this study represent the tentative reference levels and are 48.9, 44.2 and 56 Gy cm2 for all exposures, single-plane- and biplane-specific exposures, respectively, and compare favourably with the diagnostic reference level values established elsewhere internationally, with only the UK and Irish data being lower.
Advances in knowledge:
Specific agents have been identified for dose-reducing strategies and the importance of operator training is highlighted. The assumption that biplane procedures may reduce the patient dose should be treated with caution.