The feasibility study on 80 kV low tube voltage combined with SAFIRE technique in high-pitch spiral scan of CT thoracic angiography

CHEN Dan; ZHOU Jiahui; ZHOU Zuhua; JIA Chongfu

Abstract：Objective To assess the image quality and radiation dose of high-pitch spiral scan of CT thoracic angiography (CTTA) using 80 kV tube voltage and SAFIRE.Methods 60 consecutive patients with 20 kg/m2<body mass index (BMI)≤25 kg/m2 who had suspected thoracic aortic disease underwent high-pitch CTTA, Two thoracic CTA protocols (group A: n=30, 80 kV;group B: n=30, 100 kV) were compared.The parameters of CT scans were 3.2 pitch, automatic tube current modulation (CARE dosed 4 D), SAFIRE and FBP for medium soft convolution kernel.First, we compared the image quality between SAFIRE and FBP reconstruction in the same group, then, compared the image noise,signal-to-noise ratio (SNR) , contrast-to-noise ratio (CNR) and radiation dose in matched groups (group A with SAFIRE, group B with FBP).Results In the each group, the image noise with SAFIRE was greatly better than with FBP.In matched groups, the image noise was significantly higher with SAFIRE in group A than with FBP in group B〔(42.4±9.6) HU, (29.8±6.8) HU, P<0.01〕.But there were no significant differences in SNR(15.5±3.1, 15.8±3.2, P>0.05), CNR(14.5±2.9, 14.3±2.8, P>0.05) beteen them.The effective radiation dose of group A and B was 〔(0.79±0.09) mSv, (1.72 ±0.13) mSv, P<0.01), reduced about 56% in group A than group B.Conclusion To compared with 100kV voltage and FBP, high-pitch spiral scan of CTTA using 80 kV and SAFIRE can greatly reduce the radiation dose, and the image quality has no obvious difference.