铝楔双倍曝光法测试X线胶片特性曲线及应用的实验探讨

Experiment on plotting the X-ray film characteristic curve using aluminum wedge double exposure and the application

目的 利用铝楔双倍曝光法测试X线胶片特性曲线。方法 分别对铝楔、铝梯进行单倍和双倍曝光 ,将所得到铝楔、铝梯照片的单倍曝光部分和双倍曝光部分 ,用显微密度计分别进行扫描 ,把所得数据用计算机编程处理 ,得到胶片特性曲线 ,并计算出γ值 ;将两种方法所测结果相比较。结果 铝楔双倍曝光法可以测试得到连续的胶片特性曲线 ,曲线的足部和直线部显示较好 ;用该方法测出的γ值与铝梯双倍曝光法所测结果的差别在允许范围之内 ;两种方法测试所得曲线的形状相似。结论 铝楔双倍曝光法可以作为一种胶片特性曲线测试方法 ;铝楔双倍曝光法与铝梯双倍曝光法相比 ,所测曲线更连续 ,这对于程序化测试屏 片MTF曲线。

Objective: To explore a new method of plotting film characteristic curve using aluminum wedge double exposure Methods: The aluminum wedge and aluminum stairs were exposed separately, half of the wedge and the stairs was exposed once while the other half double exposed, then the image along single exposure part and the double exposure part were scanned respectively by the use of microdensitometer The data files were processed by the computer, and the film characteristic curve was plotted The γ value was also measured, then the results were compared Results: The foot part and the linear part of film characteristic curve were displayed very well; the curve and the γ value measured in this way were similar to that measured through double exposure towards aluminum stairs method Conclusion: Aluminum wedge double exposure can be used to plot film characteristic curve; and the curve is more continuous than aluminum stairs double exposure, which has the advantage in testing screen film system modulation transfer function (MTF)?Ws, etc