应用步进式扫描降低腰椎CT辐射剂量的研究

目的 探讨步进式扫描应用于腰椎CT扫描以降低辐射剂量的可行性及其临床应用价值。方法 应用体模进行基础研究,设计出可应用于腰椎扫描的新程序并得出相应扫描参数。将需行腰椎扫描的患者200例,随机分为步进式扫描组(实验组A、B)和螺旋扫描组(对照组C、D),各50例。实验组应用步进式扫描新程序进行扫描,A组为常规剂量扫描,管电压120 kV,管电流300 mAs;B组为低剂量扫描,管电压120 kV,管电流200 mAs。对照组应用螺旋扫描,C组为常规剂量扫描,管电压120 kV,管电流300 mAs,螺距0.993;D组为低剂量扫描,管电流200 mAs,余参数同C组。各组均采用标准重建算法,准直128×0.625,重建层厚1 mm,重建层间隔0.5 mm,FOV 180 mm。分别记录各组辐射剂量指数(CTDI)及有效剂量(ED),原始图像及重建图像均传输至PACS,由诊断医师对所扫图像的质量进行盲法评分(5分制)。应用SPSS统计软件对实验组和对照组的辐射剂量和质量评分进行统计分析。结果 实验组病人所受辐射剂量均低于对照组,实验组A剂量(7.16 mSv)低于对照组C(7.96±0.2 mSv)10%,实验组B剂量(4.77 mSv)低于对照组D(5.55±0.1 mSv)14%(P<0.05),实验组B剂量(4.77 mSv)低于对照组C(7.96±0.23mSv)40%。实验组A图像质量与对照组C相比差异无统计学意义,实验组B图像质量优于对照组D,差异有统计学意义(P<0.05),实验组B与对照组C图像质量差异无统计学意义(P>0.05)。结论 步进式轴扫应用于腰椎扫描存在可行性,并可大幅度降低辐射剂量。

The Research of Applications with Step-shot Scaning to Reduse Radiation Dose in Lumbar Spine CT

Objective To discuss the clinical significance and the possibilities of low dose CT scaning with stepshoot CT technology in lumbar vertebra. Methods The phantom of abdomen is needed for the basic study of the new protocol. 200 patients who underwent lumber CT scan were randomly divided into the stepshoot CT group（ experimental group A,B） and the Spiral CT group（ control group C,D）,each of 50 cases. The new protocol with stepshoot technology were performed in the experimental group; group A was routinedose group： 120 kV,300 mAs; Group B was lowdose group ： 120 kV, 200 mAs. The control group was scanned with the conventional spiral CT. Group C was routinedose group： 120 kV, 300 mAs,pitch factor of 0. 993; Group D was lowdose group： 120 kV,200 mAs,collimation128 × 0. 625,1mm slice thickness and 0. 5 mm increment,FOV 180 mm. Computed Tomography Dose Index（ CTDI） and Effective Dose（ ED） were recorded separately. The original and MPR images were transferred to the PACS and evaluated by radiologists. The data were analyzed by SPSS. Results Radiation dose of the patients of the experimental group was lower than that of the control group; the dose（ 7. 16 mSv） of group A was lower than that of group C（ 7. 96 ± 0. 23 mSv）; the dose（ 4. 77 mSv） of group B was lower than that of group D（ 5. 55 ± 0. 1 mSv）; the dose of group B was lower than that of group C（ P 0. 05）. The image quality of group A had no difference with group C（ P 0. 05）; the image quality of group B was better than group D（ P 0. 05）; there was no significant difference between the group B and C in image quality（ P 0. 05）. Conclusion Low dose CT scaning with stepshoot technology in lumbar vertebra is practicable and the radiation dose can be greatly reduced.