| Objective: At present, with the rapid development of our economic level,people’s living standard has improved, meanwhile, with the aging aggravationof our country social component, coronary atherosclerosis (coronary heartdisease) has become the most common factor which threat people’s health. As anon-invasive coronary artery examination, Multi-slice spiral CT (MSCT)coronary artery imaging which has the advantages such as safe, rapid, fewercomplications, is widely used and obtained the clinical acceptance. MSCTcoronary artery imaging generally uses retrospective electrocardiographicgating, which uses low pitch overlapping scan, and its radiation dose is high.Studies have shown that radiation dose has the potential risk to cancer for thepatients. So, more and more studies are trying to explore that how to reduce theradiation dose which patients receive.Appropriate decrease tube voltage can reduce the radiation dose from CTexamination, however, we can not blindly reduce tube voltage. Reasonable tubevoltage should be the minimum tube voltage which can guarantee imagequality and satisfy the demand of diagnosis. How to provide patients withappropriate tube voltage, improve the utilization rate of X line and reduce theradiation dose in the examination, become the most concern in the field ofradiation protection at present.The core characteristic of iDose4is double space and multiple model, itcan run the iterative calculation based on anatomical model system and noisemodel system by the double space–projection space and image space. At thesame time of without changing the image quality, eliminate the artifacts of lowphoton, reduce the image noise ratio and improve the image effect.This study which applicate iDose4technology, meanwhile, appropriate decrease the tube voltage of MSCT, runs coronary artery imaging examination,compares the image quality with the retrospective electrocardiographic gating,and compares the radiation dose in the process of examination in the two ways,explores the application of decrease tube voltage in iDose4iterativereconstructive technique in the cardiac CT coronary artery imaging.Methods:60patients were selected (BMI≤28kg/m2), male34cases,female26cases, aged39-72, the average age was54.4years. Heart rate was50-78times/minute, the average heart rate was63.48times/minute.Consecutively select30patients,19cases of male, and female in11cases, afterroutine scan, use FBP technology reconstruction, as the A1group; at the sametime and with the same patients, use iDose4technology reconstruction, thereconstructive data as the A2group; then consecutively select another30patients applying iDose4technology, at the same time, decrease the tube currentfor CT coronary artery imaging scan (group B),15cases of male and female15cases. Compare A1with A2group, and compare A2group with group B, checkthe image quality obtained on subjective evaluation and objective evaluation.Subjective evaluation compare by giving score for evaluation. Objectiveevaluation compare by image signal noise ratio and contrast noise ratio.Meanwhile, compare the radiation dose of the two groups by the machineautomatically records.Results: The subjective image quality evaluation of A1and A2, the resultis: A1group image quality average score is3.15points, A2group image qualityaverage score is3.25points, the difference was statistically significant(t=-1.87，P=0.08).The objective image quality evaluation of A1and A2, the SNR of A1is ((13.29±2.68), the SNR of A2is (17.28±3.64), the difference wasstatistically significant (P <0.05). The CNR of A1is (12.03±0.98), the CNRof A2is (15.07±3.29), the difference has no statistically significant (t=-1.08，P=0.28). The subjective image quality evaluation of A and B, the result is: A group image quality average score is3.26points, B group image qualityaverage score is3.30points, the difference has no statisticallysignificant(P=0.61). The objective image quality evaluation of A and B, theSNR of A1is (14.41±1.05), the SNR of A2is (15.07±3.29), the differencehas no statistically significant (t=-1.07， P=0.29). The CNR of A1is(12.03±0.98), the CNR of B is (13.19±2.77), the difference has nostatistically significant (t=-1.10，P=0.28). Compare the effective dose of A, Btwo groups of patients received in the process of examination, the result is: theeffective dose of A group is (11.43±10.07mSv), the effective dose of B groupis (6.60±2.50) mSv, difference was statistically significant (t=13.34, P <0.001).Conclusion: In the examination of256slice CT coronary artery imaging,application of FBP and iDose4reconstruction technology for the same case,iDose4technology can obtain better image quality. Application of iDose4technology in256slice CT coronary artery imaging, there is no differencebetween conventional scanning and decreasing tube voltage scanning in imagequality, however, radiation dose reduces about20.2%by decreasing tubevoltage. Application of iDose4technology in256slice CT coronary arteryimaging, limited decreasing tube voltage will not reduce the quality of theimage, but can reduce the radiation dose. |
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