Abstract: A radiological imaging apparatus includes an imaging apparatus having an opening for insertion of a bed thereinto, and an attenuation correction data creating device. The imaging has a plurality of radiation detectors disposed around the opening and a plurality of gamma ray generation units residing between the opening and the radiation detectors disposed at a position nearest to the opening and being placed in a longitudinal direction of the bed. Each ?-ray generation unit has ?-ray sources of single photon emission nuclear species and is arranged to externally radiate a ?-ray alternately from either one of the ?-ray generators toward the opening. The data creator prepares attenuation correction data based on a detection signal as output from the radiation detector due to the incoming radiation of ?-rays from the ?-ray generator.

Abstract: A disk reproducing apparatus is provided with first and second trays which can reciprocate between a reproducing area for storing therein a reproducing unit and a stand-by area adjacent to the reproducing area. The first and second trays are interchangeable by moving the second tray in an opposite direction to the first tray along a path formed at a higher position than that for the first tray. In this interchanging operation, the second tray being moved from said stand-by area to said reproducing area is lowered from a height position of the path situated above the first tray preferably to the same height position as the first tray set in said reproducing area. Since the described arrangement offers a smaller height difference between the first and second trays in the reproducing area, a stroke of the up-and-down movement of the reproducing unit can be made smaller, thereby achieving a reduction in size of the apparatus.