Abstract: An image is reconstituted by iterative approximation, a PET event updated image is produced by updating a current image using a PET event, a Compton event updated image is produced by updating the current image using a Compton event, the PET event updated image and the Compton event updated image that have been independently produced are weighted and added together, and the current image is updated using an image obtained by addition processing. In this way, PET events and Compton events, which have different properties, can be used in combination to efficiently and stably reconstitute images, improving image quality.

Abstract: A partial-ring PET device, in which some of coincidence radiation detectors to be arranged in a ring shape around a field of view for detecting lines of response of annihilation radiations are missing, is compensated for a drop in image quality due to the missing of the coincidence radiation detectors by including single gamma-ray radiation detectors for detecting at least either one of the annihilation radiations as a single gamma-ray. This can reduce missing of projection angles and reduce artifacts in PET images.

Abstract: A partial-ring PET device, in which some of coincidence radiation detectors to be arranged in a ring shape around a field of view for detecting lines of response of annihilation radiations are missing, is compensated for a drop in image quality due to the missing of the coincidence radiation detectors by including single gamma-ray radiation detectors for detecting at least either one of the annihilation radiations as a single gamma-ray. This can reduce missing of projection angles and reduce artifacts in PET images.

Abstract: An inclined PET device is provided in which the cut plane of a detector ring upon which a plurality of PET detectors are disposed is inclined so that it does not intersect perpendicularly with the long axis of a bed that carries a subject to be examined and in which an open space that passes through the bed in a direction perpendicular to the long axis thereof is formed, in order to enable access to the subject to be examined. The PET detectors are disposed and stacked in a direction parallel to the long axis of the bed. Thereby, the number of PET detectors is reduced and device cost is reduced, while the detector ring as well as the device can be miniaturized. At the same time, the open space that passes through the bed in a direction perpendicular to the long axis can be preserved.

Abstract: A helmet-type PET device includes a helmet portion (hemispherical detector) and an added portion (jaw portion detector, an ear portion detector, or a neck portion detector). The helmet portion includes a PET detector so as to cover a parietal region of an examination target. The added portion is positioned to dispose a PET detector at a part other than the parietal region of the examination target. PET measurement is performed using both an output from the PET detector at the helmet portion and an output from the PET detector at the added portion.

Abstract: A helmet-type PET device includes a helmet portion (hemispherical detector) and an added portion (jaw portion detector, an ear portion detector, or a neck portion detector). The helmet portion includes a PET detector so as to cover a parietal region of an examination target. The added portion is positioned to dispose a PET detector at a part other than the parietal region of the examination target. PET measurement is performed using both an output from the PET detector at the helmet portion and an output from the PET detector at the added portion.

Abstract: An inclined PET device is provided in which the cut plane of a detector ring upon which a plurality of PET detectors are disposed is inclined so that it does not intersect perpendicularly with the long axis of a bed that carries a subject to be examined and in which an open space that passes through the bed in a direction perpendicular to the long axis thereof is formed, in order to enable access to the subject to be examined. The PET detectors are disposed and stacked in a direction parallel to the long axis of the bed. Thereby, the number of PET detectors is reduced and device cost is reduced, while the detector ring as well as the device can be miniaturized. At the same time, the open space that passes through the bed in a direction perpendicular to the long axis can be preserved.