螺旋CT实际层厚的影响因素与CT图像质量的关系

目的 通过实验分析影响螺旋CT实际层厚的因素，并分析实际层厚与CT图像质量的关系。方法 应用GE Hispeed DX/1 CT机及Elscinet的QC水模在不同扫描层厚及不同螺距情况下进行扫描，测量螺旋CT实际层厚并分析。结果 螺旋CT实际层厚随扫描层厚及螺距减小而减小：Z轴分辨率及扫描时间、病人接受的放射剂量随螺距增大而增大；螺旋扫描图像噪声与螺距呈非线性关系，螺距为1、5时噪声较螺距为1.0时要小。结论 螺旋CT实际层厚与扫描层厚、螺距有密切关系，选择合适的扫描层厚及螺距对提高CT图像质量、减少扫描时间、减少病人接受的放射剂量均大有益处。

Factors affecting the real thickness of helical CT and how the real thickness relates to the quality of CT image

Objective This paper studies the real thickness of helical CT and its influencing factors by experimental analysis. Methods QC photon was scanned on helical CT (GE Hispeed DX/i) with different scan slice and pitch,the real thicknesses were measured and analysted. Results the real thickness of helical CT decrease with scan slice and pitch deceased; the resolution of Z algorithm and the roent-gen patient taken, scan time increase with pitch increased; the helical CT noise was related to the pitch. Conclusion CT scan with suitable scan slice and pitch can provide better quality of CT image, and decrease the examining time and the roentgen patient taken.