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目的:通过多项图像质量指标的检测和比较,探讨和分析双螺旋CT图像的各种分辨率.方法:采用双螺旋CT机做双螺旋与非螺旋(常规)CT扫描.检测模型:①空间分辨率;②密度分辨率;③水模;④线性CT值;⑤层厚.另收集42个病例作头部和体部扫描,在扫描条件相同的情况下,作下述分析:①常规和双螺旋CT的空间、密度分辨率、CT平均值及噪声的比较:②常规和双螺旋CT层厚敏感曲线(SSP)的比较;③从病人图像分析不同螺距和层厚对双螺旋CT纵向分辨率的影响.结果:①常规和双螺旋CT图像的空间分辨率相比无差别;密度分辨率相比,螺距=1时,双螺旋CT较常规ct好;CT平均值相比两者基本相同;图像噪声相比,双螺旋CT较低;②层厚较大时,双螺旋CT的SSP较常规CT明显增大;层厚较小时,两者的SSP基本相同;③从病人图像分析,层厚对纵向分辨率影响最大,适当选择层厚和螺距可获得良好的纵向分辨率.结论:双螺旋CT在主要质量指标和许多功能上等同于或优于常规CT,只是图像的纵向分辨率尚存不足.
Objective: To explore and analyze various resolutions of double helical CT images through the detection and comparison of a number of image quality indicators.Methods: Double helix and non-helical (conventional) CT scans were performed with double helical CT.The detection model: Resolution; ② density and resolution; ③ water model; ④ linear CT value; ⑤ layer thickness. Another 42 cases were collected for head and body scans, under the same scanning conditions for the following analysis: ① conventional and Spiral CT space, density resolution, CT average and noise comparison: ② Conventional and double helical CT layer thickness sensitivity curve (SSP) comparison; ③ From the patient image analysis of different pitch and layer thickness of the dual helical CT longitudinal resolution Rate.Results: ① There was no difference in the spatial resolution of conventional and double helical CT images. Compared with the density resolution, the helical pitch = 1, the double helical CT was better than the conventional ct; the CT average was basically the same as the two ; Compared with the image noise, the double helical CT is lower; (2) When the layer thickness is larger, the SSP of double helical CT is obviously higher than that of the conventional CT; when the layer thickness is small, the SSP of the two is basically the same; The thickness of the vertical resolution of the greatest impact, the appropriate choice of layer thickness and pitch to obtain a good longitudinal Conclusion Rate: double spiral CT in the main quality indicators and functionally equivalent to or better than many of the conventional CT, but less than the remaining vertical resolution of the image.