Objective Prospective ECG gated coronary CT angiography (pECG-CCTA) has become an alternative CT protocol. It limits radiation exposure at a narrowed predefined end diastolic time segment instead of during the entire phase of the cardiac cycle, as compared with the retrospective ECG gated coronary CT angiography (rECG-CCTA). In this study, we determined the difference in radiation dose between pECG-CCTA and rECG-CCTA.
Methods Consecutive patients who underwent CCTA were selected for our study; 29 patients underwent pECG-CCTA and 29 patients underwent rECG-CCTA. Inclusion criteria were Body mass index (BMI) of ≤30, sinus rhythm, HR≤70 bpm. Exclusion criteria were BMI ≥30, irregular rhythm, HR>70 bpm. All the patients were given β-adrenergic blockers and bromazepam to obtain heart rate of ≤70 bpm. Patients were given 50 ml of IV Iopamiro 370 at 4.0–5.0 ml/s and 50 ml saline at 4.0–5.0 ml/s. The tube voltage was constant at 100 Kvp and effective tube current was adapted according to the individual patient's body mass index. Effective radiation dose was calculated for both groups.
Results The mean effective radiation dose for the normal BMI group using pECG-CCTA and rECG-CCTA protocols were 1.7±0.2 mSv and 2.9±0.9 mSv respectively. Similarly for overweight BMI group using pECG-CCTA and rECG-CCTA protocols were 1.7±0.1 mSv and 3.8±1.7 mSv respectively. (See table 1) None of the studies had coronary images which prevented an accurate assessment of the coronary segments.
Conclusions Using a pECG-CCTA protocol as compared to a rECG-CCTA protocol, there was 41.4% and 65.3% mean radiation dose reduction for the normal and overweight BMI groups respectively.
- Coronary CT angiogram
- effective radiation dose