What is the classification of the grid?

The grid is a device that passes the original emission line and filters out the scattered lines to improve the image quality. The definitions of the original emission line and the secondary ray are the original emission line and the primary ray and the radiation emitted from the X-ray tube, and the scattered line and the secondary ray and the original emission line are injected into the human body to have a special effect on the human tissue. The generated wavelength is longer than the original emission line and the radiation direction is disordered.