The Study Of Using The Shoot-and-step Model To Reduce Radiation Dose In Cervical Spine CT Scanning

The First PartObjective：Conduct basic research, compare the shoot-and-step model with the spiralsanning and explore the superiority of the shoot-and-step model in low radiation scanningand high quality image construction. Analyze feasibility in Cervical-spine scanning.Methods:1、Review CT`s development process and characteristics;2、explore thedifferences between shoot-and-step model and the spiral sanning, different sanning modelslead to different radiation dose and image quality;3、In image construction, differentscanning models have a great influence on image duality.Result: In spiral scanning, because of the pitch with overlapping scanning andinterpolation reconstruction with oversan, it has a higher radiation dose; because of themovement of the table and cone-beam effect, its image construction cannot be as good asshoot-and-step model.Conclusion: Lower radiation dose and better image quality, shoot-and-step model can beused in Cervical-spine scanning.The Second PartObjective: In this examination, we use shoot-and-step model in Cervical-spine scanning toVerify its feasibility and the ability of reducing radiation dose.Methods: Clinical examination Eighty patients underwent Cervical CT scan wererandomly divided into the shoot-and-step model group（experimental group A,B）and theSpiral CT group（control group C,D）,each of20cases.The new protocol of axial scan were performed in the experimental group，group A were low-dose group and the parameter:120kV,200mAs,collimation128×0.625,1mm slice thickness and1mm increment，FOV200mm. Group B were routine-dose group and the scanning parameter:120kV,250mAs,theother parameters were the same to group A.The control group were scanned with theconventional spiral protocol.Group C were low-dose group and the scanning parameter：120kV,200mAs, collimation128×0.625,1mm reconstruction slice thickness and1mmincrement, pitch0.993,FOV200mm.Group D were rotuine-dose group and the scanningparameter:120kV,250mAs, other parameters were the same to group C. The originalimage and the MPR were transferred to the PACS to be evaluated by experienced doctors.Results：All images can be used to diagnose diseases and no patients need to do again forbad image quality..The density resolution and noise of shoot-and-step model are betterthan the conventional helical scan protocol Patients of the experimental group receivingradiation dose was lower than that of the control group, the dose (1.17mSv) of group Awas lower than that of group C(1.33mSv)12%, the dose (1.46mSv) of group B waslower than that of group D (1.69mSv)14%(P <0.05), the dose of group A lower thanthat of group D31%; the image quality of group A have no difference with group D, theimage quality of groupA was significantly better than group C (P <0.05), the group B andgroup D have no significant difference (P>0.05) in image quality.Conclusion: Clinical experiment shows that: in the patient Cervical scanning, withthe same scanning parameters,the density resolution and noise of axial protocol are betterthan the helical protocol scan. with the same image quality, axial protocol can reduceradiation dose for30%, are the same with the basic experimental results.Low dose CervicalCT scan using shoot-and-step model is practicable, can greatly reduce radiation dose...