X线照片影像颗粒度及其相关影响因素的探讨

Investigation of granularity of radiographic photograph image and relevant factors

目的评价不同屏片组合下Ｘ线照片影像的颗粒性，以期掌握照片颗粒性的客观评价方法，并获得影响影像颗粒度的相关因素。方法利用显微密度计对测试样本进行扫描，通过均方根（ｒｏｏｔｍｅａｎｓｑｕａｒｅ，ＲＭＳ）值的计算，对不同屏片组合的Ｘ线影像进行颗粒度的物理评价。结果通过测试和数据整理，得出颗粒度与管电压、密度、对比度及清晰度的关系。结论Ｘ线照片影像颗粒度随着管电压、清晰度和对比度的升高而升高。

Purpose To evaluate granularity of X ray film in different screen film combinations and to learn the objective method of evaluating photo graininess and obtain relative factors that influence image granularity. Methods Using microdensitometer to scan the samples and calculating the root mean square (RMS) value, physical evaluation of X ray image granularity of different screen film combinations was made. Results Through measuring and calculating data , the relation of granularity versus tube voltage, photo density, contrast or definition was obtained. Conclusion Higher tube voltage, definition or contrast, lower density yield better X ray image graininess.