Coronary CT angiography by modifying tube voltage and contrast medium concentration: Evaluation of image quality and radiation dose.

Abstract

Currently, there is an increasing interest in noninvasive imaging of cardiovascular system such as computed tomography coronary angiography (CCTA). The risks of radiation-induced cancer and contrast-induced nephropathy (CIN) have always been regarded as concerns which increased demand for CCTA using reduced radiation dose and iodine intake. We aimed to evaluate the image quality and radiation dose of CCTA by modifying tube voltage and concentration of contrast media. The present study includes 105 patients who underwent CCTA for clinical indications. Specific inclusion and exclusion criteria in terms of patient's weight, body mass index, calcium score, and stenting were used. First group of patients scanned by 120kV and 370mg I/mL contrast medium, compared with second and third groups for which scanning was performed using 100kV and 370mg I/mL and 100kV and 300mg I/mL, respectively. Image quality was evaluated both subjectively and objectively. The effective dose and iodine intake were also measured. Using low kV protocols led to radiation dose reduction up to 38% and applying low contrast medium concentration with consequent reduced iodine intake up to 21%. Moreover, there were significant differences in image quality of new scanning protocols. Reduction in tube voltage with lowering of contrast medium concentration can reduce radiation dose and iodine intake with acceptable image quality.