Application And Analysis Of 320-Raw CCTA With Lower Radiation Dose And Lower Contrast Medium In Clinical Diagnosis

Objective:To explore the clinical application of lower radiation dose and lower contrast medium technology on 320-row CT in the check of coronary diseases.Methods:120 patients suspected with coronary arterial disease underwent Coronary Computed Tomography Angiography(CCTA) from November 2014 to November 2015, and randomly divided into conventional dose group(A) and low dose group (B1,B2). Group A (n=40) used 100kV,350mg/mL iohexol 55-60ml,Group B1 (n=40) used 80kV,350mg/mL iohexol 40-45m,and Group B2 (n=40) used 80kV,320mg/mL loversol 40-45mL. Use Prospective ECG gated scan and Adaptive iterative dose reduction(AIDR) of 320-row CT.All coronary arteries were segmented according to 15 segmental approach.A 4-point method was used for assessing the overall coronary image qualities. Measure CT values of the root of ascending aorta, left coronary artery main stem, proximate right coronary artery and fat tissues around ascending aorta.Measure standard deviat (SD) of ascending aorta and calculate signal to noise ratio(SNR) and contrast to noise ratio(CNR).Record CT dose index(CTDI),dose length products(DLP),and calculate effective dose(ED). The effective iodine uptakes were calculated.Results:1. There was no significant difference on subjective assessment of image qualities in conventional dose group and low dose group(.P>0.05).2. In the objective assessment, there were no significant differences among SD, CT value of vessels,CNR of left coronary artery main stem, SNR and CNR of proximate right coronary artery(P>0.05), however, there was statistical difference in SNR of left coronary artery main stem in two groups(P<0.05),and the SNR of Group B2 was lower than the one of Group A and B1.All of them could satisfy diagnostic standards.3. The mean radiation dose of the conventional dose group was 5.323±0.992mSv, the ones of the low dose group(B1 and B2) were 1.750±0.744mSv、1.783±1.142mSv, respectively, and there were significant differences(P<0.05). Compared with Group A, ED values decreased 67.12% and 66.50% in Group B1 and B2,respectively.4. The mean effective iodine uptake of the conventional dose group was 20.125±0.886g, the ones of the low dose group(B1 and B2) were 14.875±0.886g、 13.600±0.810g,respectively, and there were statistical differences(P<0.05). Compared with Group A, the effective iodine uptakes decreased 26.09% and 32.42% in Group B1 and B2, respectively.Group B2 had the lowest iodine uptake and compared with Bl,the iodine uptake decreased 8.57%.Conclusions:1. Reducing tube voltage can obviously decrease the radiation doses,but there is no influence for image quality of 320-row CCTA.2. Reducing contrast medium concentration and dose can decrease the effective intake of iodine,but does not affect image quality of CCTA.Double-low technique is worth using widely.