Disclosed is detection system for detection an object being conveyed along a convey path, the detection system comprises a DR imaging apparatus and a CT imaging apparatus which is provided at the downstream or upstream of the DR imaging apparatus along the convey path, wherein an average speed at which the object passes the DR imaging apparatus is higher than an average speed at which the object passes the CT imaging apparatus. The present invention also relates to a DR imaging apparatus for forming an image of an object by scanning the object, the object being conveyed along a convey path, the DR imaging apparatus comprising: an X-ray source; a detector for detecting passing of the object; a digital image processing unit; and a DR. trigger module for data acquisition, wherein during the object passes the DR imaging apparatus, the DR trigger module triggers the DR imaging apparatus to perform data acquisition every time the object passes the DR imaging apparatus a predetermined distance A along the convey path.