Objective To select the appropriate noise index of the GE 64-Row VCT (Volume Computerized Tomography) Scanner in cranial CT (Computerized Tomography) so as to reasonably reduce radiation dose while meeting the requirements of clinical diagnosis. Methods Different noise indexes of the 64-Row VCT scanner were set for the patients with cerebral infarction who underwent a re-examination of cranial CT in the hospital. Then, comparisons were made through subjective and objective evaluation of the quality of images acquired in different noise indexes. Results Under the non-spiral mode, no obvious differences were found in the quality of images when the noise index < 4; the quality of images had indistinct differences but satisifed the diagnostic requirements when the noise index was between 4 to 6;the image quality was obviously decreased and could not meet the diagnostic requirements when the noise index>6. Conclusion The noise index should be set individually in consideration of the patient radiation dose while the requirements of the clinical diagnosis were also satisifed.%目的：探讨噪声指数对64排容积CT头颅扫描图像质量及辐射剂量的影响。方法对我院收治的90例脑梗塞患者复查时行64排容积CT扫描，设置不同的噪声指数，通过主观和客观评价对比说明噪声指数对图像质量的影响。结果在非螺旋模式下，当噪声指数＜4时，图像质量差异不明显；当噪声指数在4～6时，图像质量差异较为模糊；当噪声指数＞6时，图像质量明显下降，不能满足诊断要求。结论应在满足临床诊断前提下合理设置容积CT扫描的噪声指数。
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