Being related to technical are of radiation scanning imaging detection, the invention includes collimation block, correction block, servomotor, and lead screw. Being connected to output end of the servomotor, the lead screw is supported by two bearing seats. Servomotor and each bearing seat are fixed on base plate. Nut matched to the lead screw is installed on it. Characters of structure are that collimation block, and correction block arranged with gap are installed on a mounted plate so as to form an integral structure. Srpporting board is setup underside the mounted plate. Sliding plates are installed on two sides of the supporting board. Joint plate is at middle part of the supporting board. Sliding plates are placed on guide rails. The joint plate is fixed to the said nut. When the servomotor is started, collimation block, and correction block are moving integrally. Comparing with prior art, the invention saves installation space and reduces weight of equipment.