降低辐射剂量在成人颅脑CT复查中的应用及意义

目的探讨螺旋cT降低剂量扫描在成人颅脑病变复查中的应用。方法随机选取并分析2010年至011年在我院行头部cT复查的颅脑病变患者共l30例，二年内复查cT次数为2—5次．．首次复查时电流时间值降为18omAS，扫描后的图像请两位高年资CT诊断医师和二位高年资神经科医生进行盲氏阅片。评判降低剂量和常规刺量扫描图像中病变和主要结构的分辨率，以图像清晰度能满足临床诊断，可发出诊断报告作为合格标准。将图像分成”清晰”、”较清晰”、”不清晰”三级。当图像质量获得满意后将电流时问值降为15OmAS后不再继续降低。结幂130例颅脑疾病患者降低剂量后所有图像均达到诊断要求。常规剂量扫描CTDIVOl平均每次57．38mGy，采用降低剂量扫描时最低cTDIvOl为36mGY，辐射刺量降低37．3％。虽然图像质量略有下降，但不影响疾病诊断。结论有明确颅脑疾病的患者cT复查时采用150mAS扫描，图像诊断不受剂量影响，但能降低辐射刺量，具有积极的放射防护意义。

The Application and Significance of Reducing Ra- diation Dose in the Reexamining of Adult Brain CT

Objective To explore the application of reducing radiation dose in the reexam- ining of adult brain with spiral CT. Methods Selected randomly and analyzed 130 peoples with brain diseases who reexamined CT in my hospital from 2010 to 201 l year, the numbers of reexamination CT were 2-5 times in two years. The mAs was 180mAs while the first reexamining CT. Two advanced doctors of CT diagnosis and two advanced neu- rologists evaluated the quality of CT image after scanning by a bland method. Compared the disease and the resolution of main structure in the images with low doses and the normal doses. If the image clarity can meet the clinical diagnosis and can send out diagnosis report, it is a qualified standard. Divided CT images into ＂clear＂, ＂ relatively clearer＂, ＂not clear ＂ three classes. After the image quality acquired a satisfaction, the mAs was 150 mAs, and not continue to reduce radiation dose. Results The 130 peoples with brain disease reexamed CT, all images attained the diagnosis request after reducing dose. The CTDIvol of normal scans were 57.38 mGy on the average each time. The lowest CTDIvol was 36 mGy after declining doses to scan, the radiation amount reduced 37.3%. Although the image quality declined partly, it was not influence disease diagnosis. Conclusion The patients who had explicit cerebral disease were scanned by 150 mAs when they reexamined CT. The image diagnosis was not affected, but it could lower the radiation dose. It had an active signifi- cance to prevent radiation.