摘要
目的 :前瞻性评价机架旋转时间对胸部图像 ,包括横断面及多平面重建图像质量的影响。方法 :60例患者分为两组 ,采用GELightSpeedUltra 8层螺旋CT扫描仪直接增强扫描 ,机架旋转时间分别选择 0 .8s和 0 .5s。按照制订的标准 ,对比两组图像的图像质量 ,进行统计学分析。结果 :0 .8s和 0 .5s组显示野和扫描范围相似 ,两组扫描时间分别为(2 4 .9± 3 .2 )s和 (1 5 .6± 1 .7)s,差异有极显著性意义 (W =465 .0 ,P <0 .0 0 1 )。两组CTDIW(CT剂量指数 )分别为1 7.56mGy和 1 0 .98mGy,DLP(剂量长度乘积 )分别为 (480 .4± 62 .5)mGy·cm和 (30 2 .1± 35 .5)mGy·cm ,差异有极显著性意义 (W =465 .0 ,P <0 .0 0 1 )。两组图像质量平均得分为 4 .0 7± 0 .42和 4 .1 6± 0 .35 ,差异无显著性意义 (W =851 .0 ,P =0 .342 )。两组重建图像质量平均得分为 2 .43± 0 .68和 2 .50± 0 .63 ,差异无显著性意义 (W =848.0 ,P =0 .32 0 )。结论 :机架旋转时间 0 .5s组胸部图像质量略好于 0 .8s组 (差异无显著性意义 ) ;患者接受的X线剂量则明显降低 ,平均降低了 37%。建议将机架旋转时间 0 .
Objective:To determine if the shorter acquisition time of 0.5s multislice helical CT affects the image quality of thoracic CT scans,including axial image and multiplanar reconstruction (MPR) image.Methods:In 60 consecutive patients referred for thoracic CT,multislice helical CT was performed with 0.8s (n=30) or 0.5s (n=30) scanning time.All these patients were received intravenous contrast medium.2 radiologists graded all the images on a planned scale by a blind way.Statistically significant differences were determined with a Wilcoxon rank sum w test.Results:The study volume and the field of view was not statistically significant on both 0.8s and 0.5s CT scans.The total scanning time (15.6s±1.7s vs 24.9s±3.2s),CTDI W (10.98mGy vs 17.56mGy) and DLP (302.1±35.5m Gy·cm vs 480.4±62.5m Gy·cm) was statistically significant on 0.5s CT scans and on 0.8s CT scans (W=465.0, P <0.001).The axial image quality was not statistically significant on both 0.8s and 0.5s CT scans (W=851.0, P =0.342).The MPR image quality was not statistically significant on both 0.8s and 0.5s CT scans (W=848.0, P =0.320).Conclusion:Although the image quality was not statistically significant on both 0.8s and 0.5s CT scans,the score graded on 0.5s CT scans was little higher than on 0.5s CT scans.On the meanwhile,the X ray dose of patients was largely degraded by 37% on 0.5s CT scans.We suggest 0.5s gantry rotation be used routinely.
出处
《放射学实践》
2003年第4期286-289,共4页
Radiologic Practice
