X ray filter is the use of adjustable gap lead plate, obscured by the window to emit unnecessary primary rays, thereby controlling the size of the beam, changing the actual use of X-ray irradiation field.
Since X-rays are invisible rays, it is impossible to predict whether the opening size of the movable lead leaf meets the actual needs. Therefore, a point light source is placed in the x ray collimator to simulate the position of the X-ray tube focus with a light bulb. The light is reflected to the part to be illuminated by a reflector and the X-ray field is judged by the visible light field. The opening degree of lead leaves can be adjusted according to the required irradiation.
In order to make the simulated illumination field of the x ray filter reflect the X-ray illumination field correctly, the position of X-ray focus, point source and reflector is very important.
The position relation of the three is that the position of the point source and the X-ray focus must be symmetrical with the mirror as the symmetrical central axis.