X ray collimator. In the clinical application, the asymmetric collimation system has been developed with the requirement of high treatment precision and application expansion. The asymmetric collimator still retains a pair of rectangular collimators for symmetric motion, that is, symmetric opening and closing motion with respect to the center, and A pair of (generally the lower pair) rectangular collimators are asymmetrically opened or closed relative to the center, and the asymmetric collimators can move a distance (10-20 cm) from each other across the central axial countermeasure.
When a rectangular collimator is knocked at the position of the central axis of the ray, a tangential field is formed thereby, for the co-planar and co-planar adjacent fields, the tangent field irradiation of breast cancer and the tangential irradiation of the rotation therapy.
In addition to the head collimator, additional head-sized collimators of different sizes are required to be placed under the radiation head in a head stereotactic radiosurgery or stereotactic radiotherapy room using a medical electron linac.