曝光条件、IP尺寸等与CR照片影像的空间分辨力

Influences on spatial resolution of CR system

目的 :探讨曝光条件、IP尺寸等与CR照片影像空间分辨力的关系。方法 :依据Siemens点数法曝光条件表 ,在点数不变的情况下换算出摄影部位手的数组曝光条件 ,选用四种不同尺寸的IP及大小焦点 ,分别对矩形波测试卡进行摄影。采用无放大和放大 2倍的后处理技术 ,视读并记录CR照片影像的空间分辨力数值 ,分析其影响CR照片影像空间分辨力的条件。结果 :①摄影部位、曝光条件相同 ,CR照片影像的空间分辨力 ,小焦点大于大焦点 ;②摄影部位、曝光条件及焦点大小相同 ,CR照片影像的空间分辨力随IP尺寸的增加而减小 ;③CR照片影像的空间分辨力 ,放大 2倍的照片影像明显高于无放大处理的照片影像 ;④适宜的曝光条件可提高CR照片影像的空间分辨力。结论 :影响CR照片影像空间分辨力的条件 :小尺寸IP大于大尺寸IP ;小焦点大于大焦点 ;适宜的后处理放大倍数大于无放大处理 ;适宜的曝光条件组合大于其它组合。

Objective:To explore the relationship between the conditions of exposure, the size of IP and the spatial resolution in CR.Methods:Based on Siemens, figured out the several exposure conditions of hands' under the same energy. Four various IP sizes and large or small focuses are used to radiograph of the X-ray patterns. The values of the spatial resolution are read and analyzed by no-magnification or 2-time magnification technology to get out the influences on the spatial resolutions of CR system.Results:First, the value of spatial resolution with small focus is high than with the large focus. Second, the values of spatial resolution of CR will be reduced when the imaging plate turns larger. Third,the spatial resolution of two magnification CR images is higher than the resolution of no magnified images. Last, a proper condition of exposure can improve the spatial resolution of CR images.Conclusion:These are conditions of influence on the spatial resolution of CR system. The image that have small size of IP or focus, and have proper magnification or condition of exposure can have higher resolution than others.