Collimator with divergent aperture for beam of particles - esp. for neutron therapy, using stacks of lead or tungsten blocks moved synchronously to vary area of aperture

摘要

The collimator has a principal axis of symmetry which can be aligned with a source of radiation. A square or rectangular aperture is obtd. by using four stacks of blocks. Each stack slides along the adjacent stacks to increase or decrease the area of the aperture; and each stack contains the same number of blocks which are aligned along the axis and absorb the radiation. Each block is located on a pivot lever so the stacks can slide w.r.t. each other; and the pivot levers are mounted on stacks of slides. In each stack, a single motor is used to move all the slides in a homothetic manner so the slope of the aperture remains constant An efficient biological shield is formed by the blocks, and a desired aperture with accurate dimensions is easily obtd..