80 kV 64排多层螺旋CT低辐射肺动脉成像

Objective To assess the feasibility of minimizing radiation doses using 80 kV 64-row muhidetector computed tomography on pulmonary angiography.Methods 64 volunteers were derided into 2 groups to undergo MDCT pulmonary angiography(collimation,64×0.625 mm;pitch,1.204).The observed group consisting of 35 patients were for pulmonary angiography with 80 kV voltage,300 mAs,0.75 s/roation.The control group consisting of 29 patients were for pulmonary angiography with the standard tube voltage (120 kV),200 mAs,0.5 s/roation and time delay using the peak time on bolus test added 0.7 s.Volume computed tomography dose index (CTDIvol),dose length product (DLP),pulmonary vessel enhancement and back noise were quantified.Signal-noise-ratio (SNR),contrast-to-noise-ratio (CNR),weighted computed tomography dose index (CTDIw) and effective dose (E) were calculated.Results of the two protocols were compared by using t test.Two radiologists used five-point scale to subjectively score arterial enhancement and depiction of small arterial detail.The scores were compared with Mann-Whitney U test.Results The 80 kV protocol had a significantly lower DLP and E than the 120 kV protocol[(146.5±7.6)mGy·cm vs(313.4±13.5)mGy·cm,P<0.001]and [(2.5m±0.1)mGy vs (5.3±0.2)mGy,P<0.001],respectively.The 80 kV protocol and the 120 kV protocol had identical SNR(32.6±3.6 vs 31.3±2.3;P=0.089) and CNR (28.5±3.4 vs 27.6±1.1;P=0.18).No significant difference was found between the two protocols on scores for arterial enhancement and depiction of small arterial detail ( P=0.76).Conclusions 80 kV 64 slices MDCT combined with right brachiocephalic vein as the monitoring site for bolus tracking could be the first choice of pulmonary angingraphy.It can reduce the radiation dose without sacrificing the image quality.

Minimizing radiation dose of pulmonary angiography with 80 kV 64-row multidetector CT