Why do you use line filters in X-ray photography and what should you pay attention to when using them?

After X-ray passes through human body, it produces a continuous emission line with long wavelength and uncertain direction, that is, scattering line. The greater the energy of the original emission line, the thicker the penetrated limb, the higher the projection condition and the more scattered lines are produced. Scattered rays also have the functions of fluorescence and photography, which can make the film sensitive and reduce the contrast and clarity of the image. In order to reduce and eliminate the adverse effects of scattered light in projection, the most effective method is to use line filter. When using the wire filter, please pay attention to the following:

(1) line filters can be divided into parallel type and focusing type. When using the focusing line filter, we should pay attention to the focus direction, not the other way around, so as to avoid a large number of original emission lines being absorbed.

(2) The grid should be placed parallel to the film box, and the points should be aligned with the center of the film to make the film sensitive evenly.

(3) The focal length is generally not more than or less than 25% of the radius of the wire filter.

(4) The center line of the X-ray should illuminate the midpoint of the horizontal diameter of the quasi-grid. If the center line of X-ray deviates from the midpoint of the grid by 4cm, X-ray will be absorbed by about 20%, and if it deviates by 8cm, X-ray will be absorbed by more than 50%.

(5) Angle X-ray projection should be inclined along the vertical direction of the lead bar of the silk filter to avoid the original emission line being absorbed at a certain angle with the lead bar.

(6)X-rays are partially absorbed after passing through the grating, so the exposure conditions should be appropriately increased.

(7) Use the unidirectional movable linear filter to adjust the moving speed of the linear filter to make its moving time slightly longer than the exposure time.