感兴趣区大小对单源双能CT能谱成像CT值及水（碘）浓度值影响

目的:应用单源双能CT对标准水膜进行能谱扫描,探讨不同大小感兴趣区(ROI)对CT值及宝石能谱成像(GSI)水(碘)浓度值的影响。方法:利用GSI模式扫描标准水膜,层厚1.25 mm,间距1.25 mm。扫描参数:扫描视野medium,转速0.8 s/转,螺距0.984,探测器宽度40 mm,电流550 m A。以水膜中心为圆心,在水膜中心位置分别画两个面积为(600±30) mm2、(3 000±30) mm2的ROI,分别为ROI1、ROI2。将单能量图像(70ke V)载入能谱成像分析软件GSI viewer进行分析,分别测量ROI1、ROI2的CT值(HU)、水(碘)值(mg/cm3)并记录,统计学分析采用配对样本t检验,若P<0.05为差异有统计学意义。结果:ROI1的平均CT值为(2.45±1.83) HU,ROI2的平均CT值为(2.55±1.68) HU,两者之间的差异无统计学意义(P=0.06);ROI1的平均水(碘)值为(1 001.22±0.86) mg/cm3,ROI2的平均水(碘)值为(1 001.31±0.84) mg/cm3,两者之间的差异无统计学意义(P=0.135)。结论:改变ROI大小不影响单源双能CT图像中CT值和水(碘)含量的测定。 

Influence of the Size of Regions of Interest on CT Value and Material Decomposition Measurement in Water Phantom by Single-source Dual Energy CT

Objective: To investigate the effect of different size of Region of interest (ROI) on CT value and material decomposition measurement in the standard water phantom using single-source dual-energy CT. Methods: The standard water phantom provided by GE company was scanned by single-source dual-energy CT machine (Discovery CT 750HD, America GE Company). The image processing was performed on GSI Viewer browser to acquire and record CT value (HU), the concentration value of water-iodine (mg/cm3). The scanning parameters were as follows: scanning visual field: medium, rotating speed of 0.8 seconds/rotation, pitch 0.984, detector width 40 mm, current: 550mA. The two drawn ROIs were round, located in the central part of the water phantom. Their areas were (600±30) mm2 and (3000±30) mm2, and then recorded as ROI1 and ROI2 respectively. Paired samplet test was used for statistical analysis. Results: ROI1 CT value was (2.45±1.83) HU, ROI2 CT value was(2.55±1.68) HU, there was no statistical significance between CT value of ROI1 and ROI2 (P=0.06); The water-iodine value was (1001.22±0.86) mg/cm3 in ROI1, and that of ROI2 was (1001.31±0.84) mg/cm3, there was no statistical significance between water iodine value of ROI1 and ROI2 (P=0.135). Conclusions: Different ROI size will have no effect on the measurement of CT value and the concentration of water-iodine from single-source dual energy CT.