Comparison Of The Image Quality And Radiation Dose Of Different Scanning Modes In Head-neck CT Angiography

Objective:To analyze and compare the radiation dose and image quality of the different computed tomography(CT)scanning modes on head-neck CT angiography.Methods:A total of 180 patients who underwent head-neck CT angiography(CTA).The patients were divided into two groups(group A and group B)with 90 patients in each group.The groups were further subdivided according to different scanning modes:subgroups A1,A2,A3,B1,B2,and B3,with 30 patients in each subgroup.Subgroups A1 and B1 underwent the conventional CT examination;subgroups A2 and B2 underwent the k V Assist scan modes;subgroups A3 and B3 underwent the gemstone spectral imaging(GSI)protocol.All images were reconstructed with 40%pre-ASIR and 70%post-ASIR.The CT dose index(CTDIvol)and dose-length product(DLP)were recorded,and the mean values were recorded and calculated.The signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of all images were calculated when the head-neck CTA was completed.Each subjective image evaluation used a 5-point scoring method and was conducted by two independent radiologists.Results:The CT values of subgroups A1,A2,A3,B1,B2 and B3 were 361.5±44.3HU、416.6±88.5 HU、513.3±92.7 HU、352.7±43.4 HU、365.8±84.2 HU、505.7±90.6 HU.The SNRs of subgroups A1,A2,A3,B1,B2 and B3 were 35.8±7.4,37.1±9.7,44.3±13.7,28.7±7.1,28.4±7.3 and 45.6±12.7.The CNRs of subgroups A1,A2,A3,B1,B2 and B3 were 31.2±6.8,33.1±9.6,43.1±11.2,28.5±6.6,27.5±9.3 and 43.6±11.6.The EDs of subgroups A1,A2,A3,B1,B2 and B3 were 1.2±0.2 m Sv,0.7±0.1 m Sv,1.1±0.2 m Sv,1.3±0.4 m Sv,1.1±0.3 m Sv and1.2±0.4 m Sv.The subjective scores of subgroups A1,A2,A3,B1,B2 and B3 were 3.8±0.2,4.1±0.3,4.4±0.3,3.0±0.2,3.1±0.2 and 4.4±0.4.The SNRs,CNRs,and subjective scores of subgroups A3 and B3 were higher than the other subgroups(P<0.05).In subgroups B1 and B2,the subjective scores of nine patients and 12 patients were lower than 3,respectively.The subjective scores of subgroups B1 and B2 were lower than the other subgroups(P<0.05).There was no statistically significant difference in SNRs,CNRs,and subjective scores between subgroups A1and A2(P>0.05).The ED(0.7±0.1 m Sv)of subgroup A2 was 41.7%and 36.4%lower than that in subgroups A1(1.2±0.2 m Sv)and A3(1.1±0.2 m Sv),respectively(P<0.05).In group B,there were no statistically significant differences in CTDIvol,DLP,and ED(P>0.05).Conclusion:In the head-neck CTA,the k V Assist scan mode is recommended for patients with BMI of 18.5 kg/m~2≦BMI<34.9 kg/m~2;GSI scanning mode is recommended for patients with BMI of≥34.9 kg/m~2.