层面位置对西门子CT模拟机图像噪声的影响

目的通过实验分析水模体的CT图像数据,探讨层面位置对西门子CT模拟机图像噪声的影响。方法调用西门子Sensation Open CT模拟机的日常质量检测程序,使用水模体进行10次测量,得到两种情形(标称管电压120 kV和140 kV)相邻的六层(S1~S6)CT图像。通过手工勾画得到感兴趣区CT值的标准偏差值(图像噪声)数据。对不同层面位置的图像噪声数据进行统计分析和比较研究。结果120 kV情形下,S1~S6层的图像噪声分别为(10.73±0.05)、(10.66±0.05)、(10.58±0.09)、(10.58±0.08)、(10.72±0.06)、(10.88±0.06)HU;140 kV情形下,S1~S6层的图像噪声分别为(10.09±0.09)、(10.02±0.04)、(9.90±0.07)、(9.93±0.05)、(10.1±0.09)、(10.17±0.12)HU。统计分析显示,不同层面的图像噪声数据总体上有统计学差异。结论层面位置对西门子CT模拟机图像噪声有影响,中心层面位置的图像噪声小于两端层面的数值。

Influence of Slice Position on Image Noise for a SIEMENS CT Simulator

Objective To study influence of the slice position on image noise for SIEMENS CT simulator by analyzing the experimental CT image data using the water phantom.Methods The daily quality check program for the SIEMENS Sensation Open CT simulator was utilized for 10 measurements with a water phantom,and the CT images of 6 neighboring slices(S1-S6)were obtained under two conditions of the nominal tube voltages of 120 kV and 140 kV,respectively.Then the values of image noise were obtained by manual delineation with the region of interest.Statistical analysis and comparative study were conducted on the image noise data for different slice positions.Results Under the case with the nominal tube voltages of 120 kV,the values of image noise for the first to sixth slices were(10.73±0.05),(10.66±0.05),(10.58±0.09),(10.58±0.08),(10.72±0.06),and(10.88±0.06)HU,respectively.Under the case with the nominal tube voltages of 140 kV,the corresponding values were(10.09±0.09),(10.02±0.04),(9.90±0.07),(9.93±0.05),(10.1±0.09),(10.17±0.12)HU,respectively.Statistical analysis showed that overall there was statistical difference in image noise at different slice positions.Conclusion The slice position has influence on the image noise of the SIEMENS CT simulator.The values of image noise in the middle slice position are smaller than those in the two ends.