PET scanner and image reconstruction method thereof
View Patent ↗A plurality of detector rings in which detectors arranged densely or spatially in a ring shape or in a polygonal shape are arranged, with an open space kept in the body axis direction, coincidences are measured for some of or all of detector pairs connecting the detector rings apart from the open space to perform three-dimensional image reconstruction, thereby imaging the open space between the detector rings as a tomographic image. Therefore, the open space is secured, with the deteriorated quality of an image suppressed, thus making it possible to easily gain access to a patient under PET scanning from outside a gantry and also provide irradiation of particle beams for cancer treatment as well as X-ray CT scanning.
1. A Positron Emission Tomography (PET) scanner comprising:
a gantry; and
a plurality of sets of detector rings, each set including a plurality of detector rings, with an open space between the sets of detector rings kept in the body axis direction, wherein
each detector ring comprises detectors that are arranged densely or spatially in a ring shape or in a polygonal shape,
coincidences are measured for some of or all of detector pairs connecting the sets of detector rings apart from the open space to perform three-dimensional image reconstruction, thereby imaging the open space between the sets of detector rings as a tomographic image, and
the gantry is completely or partially separated horizontally at the open space, allowing access to a patient from outside the gantry.
2. The PET scanner according to claim 1 , wherein the coincidences are measured not only for some of or all of detector pairs connecting the sets of detector rings apart from the open space but also for some of or all of detector pairs within the same detector rings to perform the three-dimensional image reconstruction, thus making it possible to image as a tomographic image a continuous region which combines a field-of-view within each of the detector rings with the open space.
3. The PET scanner according to claim 1 , wherein, among open spaces secured between sets of detector rings, detectors are arranged at open spaces among sets of detector rings, thus making it possible to improve the detector sensitivity and also improve the quality of a PET image.
4. The PET scanner according to claim 1 , wherein
each set of detector rings is structured so as to translate in the back and forth direction, and a clearance between the sets of detector rings in the body axis direction is made variable.
5. The PET scanner according to claim 1 , wherein the PET scanner is configured to monitor treatment to a site by a therapeutic beam, where the therapeutic beam is configured to pass through the open space between the sets of detector ring.
6. The PET scanner according to claim 1 , wherein when an X-ray Computed Tomography (CT) scanner is inserted at least partially into a clearance region between sets of detector rings to image a site, the PET scanner simultaneously images the site.
7. The PET scanner according to claim 1 , wherein
a sensitivity width defines a width of a field of view of the PET scanner in the open space between a first set of detector rings and a second set of detector rings,
a diameter and a width of the first set of detector rings, a diameter and a width of the second set of detector rings, and a width of the open space are configured such that the sensitivity width is greater than the width of the open space in a body axis direction,
the sensitivity width overlaps an edge of the first set of detector rings adjacent to the open space and an edge of the second set of detector rings adjacent to the open space in the body axis direction, and
a diameter of the field of view of the PET scanner in the open space is greater than an examination target region to be imaged.
8. An image reconstruction method for a Positron Emission Tomography (PET) scanner, wherein on calculating image reconstruction of the PET scanner described in claim 1 , a system matrix to be calculated or referred is changed in accordance with the arrangement of detectors.