There are two types of simple collimator: wire-shielding plate and wire-shielding tube.
The wire-shielding plate type is to additionally install a lead plate with a square or circular hole of a certain size on the window of the x pipe sleeve. The opening of the lead plate is centered on the X-ray as the center of symmetry. When the projection is performed, an irradiation field suitable for the size of the hole can be obtained at a certain distance. Generally, an X-ray machine is equipped with a plurality of shielding plates with different apertures, and the size of the irradiation field at the corresponding distance is indicated on the top, so that it can be selected for use.
The shape of the wire-cutter tube beam limiter is a conical metal tube, and some are lined with thin lead to increase the protective effect. When projecting, it mainly restricts the irradiation field by blocking and absorbing X-rays on the wall of the cylinder. Therefore, the size of the irradiation field can be determined by the length and diameter of the reticle. The irradiation field is generally circular.