The Clinical Application Of Low Dose Technique And Reducing The Artifact On Head With Dual-source CT

Objective(1) To evaluate the feasibility of the head plain scan of100kV with Sinogram Affirmed Iterative Reconstruction(SAFIRE) reconstruction technique of the new dual-source.(2) To explore the value of the head plain scan of intelligent optimal kV scanning technology (CARE kV) in the new dual-source CT.Materials and Methods(1)Dual-source CT head plain scan was performed in60consecutive patients. Patients in group A(n=30) underwent120kV scanning with CARE Dose4D techniques(Ref. kV=120,Quality ref.mAs/rot=320).Patients in group B(n=30) underwent1OOkV scanning with CARE Dose4D techniques(Ref.kV=120, Quality ref.mAs/rot=320).Group C was reconstructed using SAFIRE reconstruction at1strengths.Group D was reconstructed using SAFIRE reconstruction at2strengths.Group E was reconstructed using SAFIRE reconstruction at3strengths.Group F was reconstructed using SAFIRE reconstruction at4strengths.Group G was reconstructed using SAFIRE reconstruction at5strengths.The difference between seven groups in image quality, mean CT values, images noise, Signal-to-noise ratio, Contrast-to-noise ratio and radiation dose were compared. (2) Dual-source CT head plain scan was performed in60consecutive patients. Patients in group A(n=30) underwent CARE kV(On) combined with CARE Dose4D techniques(Ref. kV=120,Quality ref.mAs/rot=320).Patients in group B(n=30) underwent CARE kV(Off) combined with CARE Dose4D techniques(Ref.kV=120, Quality ref.mAs/rot=320).The difference between two groups in image quality, mean CT values, images noise, Signal-to-noise ratio, Contrast-to-noise ratio and radiation dose were compared.Results(1)The mean CT value has no statistical significance difference between seven groups (P>0.05).The image noise has significant differences between seven groups (P<0.05). With LSD-t method of cerebral white matter and gray matter SD values are compared, and out of group A and group C, group F and G group, between the other groups were statistically significant (P<0.05). Group B to group G SD value gradually reduced. Group B than in group A of cerebral white matter SD value increased by10.33%, C to G group compared with group B SD value by14.89%,24.68%,32.34%,42.13%,45.53%. Group B than in group A gray matter SD value increased by15.2%, C to G group compared with group B SD value by10.76%,19.44%,27.78%,37.15%,43.75%.The white matter and gray matter of SNR and CNR was statistically difference (P<0.05), and then using LSD-t method of7groups of SNR and CNR pairwise comparison, and out of group A and group B, group A and group C,group F and G has no statistical difference, the other groups were statistically significant (P<0.05); Gray matter SNR out of group A and group C, group B and group C, group F and G group has no statistical difference, the other groups were statistically significant (P<0.05). CNR out of group A and group B, group A and group C, group A and group D, group B and group C, group C and group D has no statistical difference,the other groups were statistically significant. The mean image quality scores in patients scanned with seven groups were (4.03±0.67),(4.00±0.69),(4.03±0.67),(4.10±0.55),(4.20±0.48),(4.10±0.55) and (3.93±0.78), there was no statistical difference between the three groups (P>0.05). The effective radiation dose was (2.11±0.24) mSv for group A,(1.73±0.26) for group B,which the difference was statistically significant between two groups (P<0.05),and group B reduce by18%.. (2) The mean CT value has no statistical significance difference between seven groups (P>0.05).The image noise has significant differences between seven groups (P<0.05). The white matter image noise of group A compared with group B increased by4.33%, the gray matter image noise compared with group B increased by3.32%.And the SNR and CNR was no statistic difference between the five groups (P>0.05). The white matter SNR of group A than group B by2.72%, the gray matter SNR1.88%lower than group B, CNR reduced by3.86%. The mean image quality scores in patients scanned with two groups were(4.00±0.59) and (4.10±0.55), there was no statistical difference between the three groups (P>0.05) The effective radiation dose was (1.63±0.12) mSv for group A,(2.10±0.25) for group B.which the difference was statistically significant between two groups (P<0.05),and group B reduce by22.6%..Conclusion(1) Using100kV tube voltage scan protocol with SAFIRE reconstruction technique is feasible in patients with head plain CT scan. The scan protocol can substantially reduce radiation doses while preserve good diagnostic image quality.And the best SAFIRE reconstruction strengths is level3.(2) Using CARE kV (On) combined CARE Dose4D techniques (Ref. kV=120, Quality ref. mAs/rot=320) with dual-source CT head plain CT scan is feasible in patients The scan protocol can substantially reduce radiation doses while preserve good diagnostic image quality. Part II the Application of Reducing the Artifact on Head with Dual-source CTObjective(1) Our study was to evaluate,provide new image selection and prognostic evaluation for the clinical application with dual energy monoenergetic in the clipped intracranial aneurysms through the aneurysm patients with dual-source CT scans and monoenergetic software.(2) Our study was to evaluate multiple post-processing methods to reduce the application value of posterior fossa artifact.Materials and Methods(1) The40consecutive patients clipped intracranial aneurysms were performed in Dual-source brain CT angiography,then using Monoenergetic software for image analysis and divided into sixteen groups which were10keV interval to do the postprocessing with metal artifacts.Evaluating the mixture group and every10keV groups in the objective indicator and imaging artifacts.(2) The40consecutive patients who need head CT scan and have posterior fossa artifacts do the multiple post-processing methods to reduce the application value of posterior fossa artifact. Group A’s kernel is D30,group B’s kernel is D24, group C’s kernel is D34, group D is Q3that group A after SAFIRE3reconstruction, group E of16is the Monoenergetic software group images, group F is Q3after Monoenergetic software. Evaluate separately in group A to D and E, F group16groups of the posterior fossa of the image artifact, and analysis artifacts index and contrast to noise ratio of region of interest.Results(1) Artifacts index of40-90kev groups are higher than the mixed group, there was no difference in the90kev group and mixed group, and100-190kev group were lower than mixed group. Contrast-to-noise ratio of40-60kev group and120-190kev groups are lower than the mixed group, and there was no difference in the70-110kev group and mixed group, but the number of80-100kev groups are higher than the mixed group. The artifacts of40-90kev groups in subjective image quality of soft tissue reduce not obvious, but100-190kev groups were obviously reduced and the score increased. The metal clip of40-90kev groups in image quality is improved, the artifacts of100-190kev groups decreased significantly than mixed group.(2)There was no statistical significance difference in the mean CT value of the sixr groups (P>0.05), the SD value and SNR were statistically significant (P<0.05), and the group F’s SD is the minimum and SNR is the largest. Two groups of16subgroups in E,F’s CT value descending with the keV ihcrease,the80keV’s SD is the minimum,the SNR maximum.Conclusion(1)Dual energy CT Monoenergetic can eliminate or reduce the artifacts caused by metal clip after selecting appropriate energy, the influence of the processed image is made more conforms to the needs of the clinical work.(2)The D30after SAFIRE level3reconstruction image can reduce the artifacts; D30after SAFIRE level3and the monoenergetic software image has better effect to reduce the artifacts. The simple convolution kernels D24is the best.