Purpose To explore the feasibility of"one key"individualized low-dose CT colonography(CTC)via auto-prescription technique.Materials and Methods A total of 131 patients who underwent CTC examination were prospectively collected from October 2021 to June 2022 in the First Affiliated Hospital of Dalian Medical University.All patients were scanned twice in prone(group A)and supine positions(group B).The tube voltage in prone position was 120 kVp combined with 30%adaptive statistical iterative reconstruction-veo(ASIR-V).The tube voltage in supine position was in auto-prescription mode,combining with 70%ASIR-V.The rest scanning parameters were remained the same.The body mass index,volume CT dose index(CTDIvol)and dose length product(DLP)were recorded,respectively.The signal-to-noise ratio(SNR)and contrast noise ratio(CNR)were calculated by measuring the CT and standard deviation(SD)values of air of intestine(background)and liver parenchyma on axial images.Two observers used a 5-point scale to evaluate the image quality of the two groups,and the consistency test was performed to test the inter-observer consistency.The differences in image quality and radiation dose were compared between the two groups.Results The kVp value in group B(body mass index:17.96-32.05 kg/m2)were 70 kVp(4/131),80 kVp(64/131),100 kVp(61/131),120 kVp(2/131),respectively.Compared with group A[(5.57±0.13)mGy and(291.80±7.46)mGy·cm],the CTDIvol and DLP of group B[(3.79±0.14)mGy and(189.70±7.48)mGy·cm]decreased by 33.94%and 36.91%(Z=9.931,both P<0.05),respectively.There was no statistically significant difference in the liver and air CT value between group B and group A(t=1.888,-1.218,P>0.05),SD value of group B was significantly lower than that of group A,the SNR and CNR of group B were significantly higher than those of group A(t=-33.200,-41.617,16.083,57.748,all P<0.05).Conclusion Application of auto-prescription technique in low-dose CTC can further reduce the radiation dose with maintaining the image quality,and can realize"one-click"individualized low-dose CTC,which has important clinical application value.
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