Application Of Low Dose Iterative Reconstruction Combined With Low Contrast Agent In Cervical CTA

Part 1: Different tube voltage and tube current in combination with iterative reconstruction on CTA scanning: phantom studyObjective: To explore CT value change rule of Iodine contrast agent with different tube voltage and tube current, the role in reducing radiation dose with Lower tube voltage and tube current, the scan conditions of getting the best image SNR, SNR values,And the influence of image quality with FBP and i Dose41-6 reconstruction levels, By establishing an in-vitro model test, froming different concentrations iodine contrast agent, using different tube voltage, tube current and iterative reconstruction. Methods:1. Using the nonionic contrast medium(370 mgi/ml) respectively diluted into eight different concentrations iodine solution with saline water; The scan conditions of different tube voltage(120, 100 and 80 kv) and tube current(50, 100, 200, 250, 300, m As); And three groups of using 100 m As place image FBP and i Dose1-6 levels of image reconstruction. 2. Recording each group image volume CT Dose index(CT dosed index- volume, CTDIvol), all of the images of CT values, SNR, CNR and noise, and the subjective image quality scor, followed by statistical analysis.Results: 1. In the case of the same tube current, different tube voltage of CT value was statistically significant(P < 0.05), and with the loss of the tube voltage, the CT value increased gradually;And under the condition of the same tube voltage,different tube current of CT value difference is not statistically significant(P > 0.05).2. The radiation dose and tube voltage and tube current isproportional to the relationship. Image noise is decreased gradually with the increase of tube current.3. Scan conditions for 80 kv and 300 m As can get best CNR, SNR values. 4. FBP and i Dose1-6 groups of CNR, SNR, and the average SD comparison were statistically significant(P < 0.05), and the CT value difference of iodine contrast agent has no statistical significance(P > 0.05).Place(2) FBP and i Dose1-6 groups of the subjective image quality score difference was statistically significant(P < 0.05), and i Dose- 3, i Dose- 4 have the best image quality. Conclusion: 1. Tube voltage change can lead to iodine contrast agent CT value changes;And the change of the tube current to iodine contrast agent of CT is worth little impact. 2. using lower tube voltage,higher tube current can reduce noise and radiation dose,Scan conditions for 80 kv and 300 m As can get best CNR, SNR values.3. FBP CNR and the level of i Dose1-6 reconstruction image, SNR, and there are differences between the average SD, no obvious difference was found between CT value and iodine contrast agent. FBP and i Dose1-6 groups of the subjective image quality score difference was statistically significant, i Dose- 3, i Dose – 4 are the best image quality.Part 2: The value of using low doses and iterative reconstruction in combination with low contrast medium in Cranial CTAObjective: To explore the value of using low doses and iterative reconstructionin combination with low contrast medium in Cranial CTA, By Computing image objective indicators: CT value, CNR, SNR, radiation dose and the subjective image quality score. Methods: choose 60 patients of head CTA scanning from June 2014 to December, randomly divided into A, B two groups, each group 30 cases. Scanning conditions are as follows: group A(control group) : 120 kv, 250 mas, contrast medium 60 ml; Group B(experimental group), 80 kv, 300 mas, contrast medium 40 ml.2. Recording A, B two groups of radiation dose, calculating the average head CTA reinforcement CT value; And calculating each image SNR and CNR value.3. Two senior imaging diagnostic physicians evalue the subjective image quality score by double-blind method.(3) pass all the raw data of group B to GE AW4.4 image post-processing workstation, and compared with philips workstation post-processing images. Followed by statistical analysis. Results: 1. The comparison of two groups of radiation dose: group B than in group A decreased by 64.3%. 2. Image Objective evaluation: the average CT value, SNR and CNR value differences of A and B group are statistically significant(P < 0.05).And the average CT value, SNR and CNR value of group B are higher than the value of group A. 3. Image subjective evaluation: The image subjective image quality score of the two groups have no statistical difference(P > 0.05).And two doctors to assess the consistency of the CTA images(Kappa value > 0.75). 4. The comparison of two groups of contrast agent: The contrast agent of A, B groups are respectively 40, 60 ml, group B than in group A contrast agent was reduced by 33.3%.5. The comparison of two kinds ofpost-processing workstation: the post-processing time was statistically difference(P < 0.05) and the processing time of EBM are faster than AW4.4.And the image quality score of two post-processing workstation is not statistically significant(P > 0.05).Conclusion: using low doses and iterative reconstruction in combination with low contrast medium in Cranial CTA improve the SNR and CNR value of images, not only can satisfy the need of diagnosis, also can greatly reduce the patients accepted doses of radiation.