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X线摄影的目的,就是掌握和控制X线照片影像的形成,向医师提供赖以诊断的依据。一张X线照片能在多大程度上反映被照体的正常与异样变化,需要对影像质量进行评价。这种评价主要是通过测知照片影像反映出的密度与曝光量的关系、调制传递函数以及对颗粒度的评定来做出的,进而通过实验研究来提高影像质量。但是,要测知密度与曝光量之间的关系,则需要通过特性曲线的测定才能实现。下面我们就着重讨论这一问题。
The purpose of X-ray photography is to master and control the formation of X-ray images and provide doctors with a basis for diagnosis. To what extent an X-ray can reflect the normal and abnormal changes in the subject, the image quality needs to be evaluated. This evaluation is mainly through the detection of the relationship between the density of the photo image and exposure, modulation transfer function and the assessment of the particle size to make, and then through experimental research to improve image quality. However, to determine the relationship between density and exposure, you need to measure the characteristic curve to achieve. Below we will focus on this issue.