Achieving consistent image quality and overall radiation dose reduction for coronary CT angiography with body mass index-dependent tube voltage and tube current selection

•BMI-dependent kVp and mA selection method may be established in CCTA.•BMI-dependent kVp and mA enables consistent CCTA image quality.•Overall dose reduction of 40% can be obtained with BMI-dependent kVp and mA.

AimTo develop a quantitative body mass index (BMI)-dependent tube voltage and tube current selection method for obtaining consistent image quality and overall dose reduction in computed tomography coronary angiography (CTCA).Methods and materialsThe images of 190 consecutive patients (group A) who underwent CTCA with fixed protocols (100 kV/193 mAs for 100 patients with a BMI of <27 and 120 kV/175 mAs for 90 patients with a BMI of >27) were retrospectively analysed and reconstructed with an adaptive statistical iterative reconstruction (ASIR) algorithm at 50% blending. Image noise was measured and the relationship to BMI was studied to establish BMI-dependent tube current for obtaining CTCA images with user-specified image noise. One hundred additional cardiac patients (group B) were examined using prospective triggering with the BMI-dependent tube voltage/current. CTCA image-quality score, image noise, and effective dose from groups B and C (subgroup of A of 100 patients examined with prospective triggering only) were obtained and compared.ResultsThere was a linear relationship between image noise and BMI in group A. Using a BMI-dependent tube current in group B, an average CTCA image noise of 27.7 HU (target 28 HU) and 31.7 HU (target 33 HU) was obtained for the subgroups of patients with BMIs of >27 and of <27, respectively, and was independent of patient BMI. There was no difference between image-quality scores between groups B and C (4.52 versus 4.60, p > 0.05). The average effective dose for group B (2.56 mSv) was 42% lower than group C (4.38 mSv; p < 0.01).ConclusionBMI-dependent tube voltage/current selection in CTCA provides an individualized protocol that generates consistent image quality and helps to reduce overall patient radiation dose.