RESUMO
Objective To assess the feasibility of computed tomography angiography (CTA) in renal artery using the iterative reconstruction technique (iDose4) in Brilliance iCT (Philips Ltd.).Methods 90 patients (body weight 60-70 kg) supposed to undergo renal artery CTA were selected and randomly divided into three groups:A(120 kV,120 mAs),B(120 kV,60 mAs) and C(100 kV,100 mAs).CTA images from Group A were obtained using filtered back projection and those from the rest groups were generated by iDose4.Then CT number of renal artery,noise (denoted as standard deviation SD),signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of images for each group were measured and recorded.Images were post-processed using volume reformation (VR) 3D imaging and image quality were assessed in five-level grade (1-5).Results The five parameters (CT number of renal artery,SD value,SNR,CNR and VR grade) of group A and group B were statistically insignificant (P ＞ 0.05).While SD values of group C were comparable to those of group A and B,the rest four parameters of group C were apparently larger,which was statistically significant (tCT value =-12.326,tSNR =-7.136,tCNR =-7.649,ZVR =-2.690,PVR ＜ 0.05).Conclusions Image quality could still fit the diagnosis requirements using iDose4 when mAs decreased lower than 50％.The image quality increases when radiation dose is halved at 100 kVp kV.