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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。
OBJECTIVE: To investigate the effect of ROI on CT value and GSI water (iodine) concentration by single-source dual-energy CT scanning of standard water film. Methods: A standard water film was scanned using GSI mode with a layer thickness of 1.25 mm and a pitch of 1.25 mm. Scanning parameters: scan field medium, speed 0.8 s / rev, pitch 0.984, detector width 40 mm, current 550 m A. Taking the center of the water film as the center, two ROIs with the area of (600 ± 30) mm2 and (3 000 ± 30) mm2 were respectively drawn in the center of the water film, which were ROI1 and ROI2, respectively. Single energy images (70ke V) were loaded into the GSI viewer software for energy spectrum analysis. The CT values (HU), water (iodine) values (mg / cm3) of ROI1 and ROI2 were measured and recorded. Sample t test, if P <0.05 for the difference was statistically significant. Results: The average CT value of ROI1 was (2.45 ± 1.83) HU, and the average CT value of ROI2 was (2.55 ± 1.68) HU. There was no significant difference between the two groups (P = 0.06) ) Value was (1 001.22 ± 0.86) mg / cm3, and the average water (iodine value) value of ROI2 was (1 001.31 ± 0.84) mg / cm3. There was no significant difference between them (P = 0.135). Conclusion: The change of ROI size does not affect the determination of CT value and water (iodine) content in single-source dual-energy CT images.