1. A radiological imaging apparatus comprising: a plurality of radiation detectors for detecting a plurality of radiations from a subject; a signal processing apparatus connected to one of said plurality of radiation detectors, for processing radiation detection signals detected by said radiation detectors; and a computer for reconstructing a PET image or a SPECT image by performing in-vivo attenuation correction to a PET image or a SPECT image using a rate of attenuation of X-ray detection signals from an X-ray CT apparatus located separately, wherein a phenomenon that radiations scatter in a body of a subject is corrected by said in-vivo attenuation correction.