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目的探讨眼眶部螺旋CT检查螺距变化与图像质量、辐射剂量的相关性。方法分析80例眼眶部螺旋CT扫描的断面图像和重组图像,螺距分别为0.75、1.5各40例。同时记录容积CT剂量指数(CTDIvol)和剂量长度乘积(DLP)。图像质量从影像层次、背景噪声、解剖结构及能否满足诊断要求等方面进行综合评价;图像资料采用χ2检验。结果螺距0.75、1.5的CTDIvol和DLP分别为23.01 mGy、131.18 mGy.cm和11.51 mGy、69.04mGy.cm,呈负相关;两组断面图像和重组图像的质量间差异无统计学意义(P>0.05)。结论眼眶部螺旋CT检查螺距设置1.5时,既能获得良好的图像质量,又能有效地降低辐射剂量。
Objective To investigate the correlation between pitch change and image quality and radiation dose in orbital spiral CT examination. Methods 80 cases of orbital spiral CT scan of the cross-sectional images and recombinant images, pitch were 0.75, 1.5 each 40 cases. Volume CT dose index (CTDIvol) and dose length product (DLP) were also recorded. Image quality from the image level, background noise, anatomical structure and the ability to meet the diagnostic requirements and other aspects of a comprehensive evaluation; image data using χ2 test. Results The CTDIvol and DLP at the lead distances of 0.75 and 1.5 were negatively correlated with the values of 23.01 mGy, 131.18 mGy.cm and 11.51 mGy, 69.04 mGy.cm respectively. There was no significant difference between the two groups in the quality of images (P> 0.05) ). Conclusion When the pitch of orbital spiral CT is set to 1.5, the good image quality and the effective radiation dose can be achieved.