眼眶部螺旋CT检查螺距选择与辐射剂量的相关性探讨

The Research of the Relativity Between the Pitch and Radiation Dose at Orbital Helical CT

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 investingate the relativity of orbital helical CT pitch changes,image quality and radiation dose.Methods 80 cases of orbital spiral CT scan of the sectional images and reconstructive images were analyzed.The pitch were respectively 0.75,1.5 with 40 cases in each.At the same time CT dose index（CTDIvol） and the dose length product（DLP） were recorded.Image quality was evaluated according to its low-density resolution,background noise,anatomic structure and whether it could meet the diagnosis requirements.The image data were analyzed by χ2 test.Results The CTDIovl and DLP of Pitch 0.75,1.5 CTDIovl and DLP were 23.01 mGy、131.18 mGy·cm and 11.51 mGy、69.04 mGy·cm respectively,in a negative relationship;two sets of image quality difference had no statistical significance（P〉 0.05）.Conclusion Orbital helical CT with 1.5 pitch,not only obtain good image quality,but also can effectively reduce radiation dose.