Abstract: In radiography apparatus a moving slit collimator is disposed between an X-ray source and a patient undergoing examination. Radiation is detected with an X-ray image intensifier and television pickup chain. The field of view of the television pickup is limited to that area of the output screen of the X-ray image intensifier which corresponds to the image produced by direct radiation which passes through the moving slit. The view of the television pickup may be limited by a second slit, disposed between the X-ray image intensifier and television pickup which moves in synchronism with the first slit. Alternately, the view of a television pickup may be limited by synchronizing scan signals for the pickup of the with the motion of the slit collimator.