Pet reconstruction for adjustable pet system

Patent metadata

Field	Value
Publication number	US-12318232-B2
Application number	US-202217963737-A
Country	US
Kind code	B2
Filing date	Oct 11, 2022
Priority date	Oct 11, 2022
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

A PET scanner includes gamma-ray detector rings that form a bore through which an imaging subject is translated, a length of the bore defining an axial length of the PET scanner, the gamma-ray detector rings being movable along the axial length, the gamma-ray detector rings including gamma-ray detector modules therein, and processing circuitry configured to receive PET data associated with a plurality of transaxial slices of the imaging subject, the PET data including a first set of spatial information and timing information corresponding to a first data acquisition period for the gamma-ray detector modules in a first axial position and a second set of spatial information and timing information corresponding to a second data acquisition period for the gamma-ray detector modules in a second axial position, and reconstruct a PET image based on the first set of spatial and timing information and the second set of spatial and timing information.

First claim

The invention claimed is:

1. A positron emission tomography (PET) scanner, comprising:
a plurality of gamma-ray detector rings that form a bore through which an imaging subject is translated, a length of the bore defining an axial length of the PET scanner, the plurality of gamma-ray detector rings being movable along the axial length, the plurality of gamma-ray detector rings each including gamma-ray detector modules therein, and
processing circuitry configured to
receive PET data associated with a plurality of transaxial slices of the imaging subject, the PET data including a first set of spatial information and timing information corresponding to a first data acquisition period for the gamma-ray detector modules in a first axial position along the axial length and a second set of spatial information and timing information corresponding to a second data acquisition period for the gamma-ray detector modules in a second axial position along the axial length, and
reconstruct a PET image based on the received PET data, including the first set of spatial information and timing information and the second set of spatial information and timing information,

wherein for each line of response (LOR) and for each position of the first axial position and the second axial position:
the corresponding spatial information includes respective positions of two crystals defining the LOR, and
the corresponding timing information includes a start time and an end time of data acquisition for each of the two crystals,

wherein the gamma-ray detector modules are disposed in at least two axial positions during a scan of the imaging subject,
wherein the start time and the end time are saved separately for each position of the gamma-ray detector modules, and
wherein the processing circuitry is further configured to reconstruct the PET image using a sinogram-based iterative reconstruction process based on each line of response (LOR) connecting corresponding locations within two of the gamma-ray detector modules detecting an annihilation event having a different start time and end time corresponding to each of the at least two axial positions, the sinogram-based iterative reconstruction process being further based on a geometry normalization factor, a scatter correction factor, and a random correction factor.

2. The positron emission tomography scanner according to claim 1 , wherein the at least two axial positions are different for any particular gamma-ray detector module of the plurality of gamma-ray detectors.

3. A positron emission tomography scanner, comprising:
a plurality of gamma-ray detector rings that form a bore through which an imaging subject is translated, a length of the bore defining an axial length of the PET scanner, the plurality of gamma-ray detector rings being movable along the axial length, the plurality of gamma-ray detector rings each including gamma-ray detector modules therein, and
processing circuitry configured to
receive PET data associated with a plurality of transaxial slices of the imaging subject, the PET data including a first set of spatial information and timing information corresponding to a first data acquisition period for the gamma-ray detector modules in a first axial position along the axial length and a second set of spatial information and timing information corresponding to a second data acquisition period for the gamma-ray detector modules in a second axial position along the axial length, and
reconstruct a PET image based on the received PET data, including the first set of spatial information and timing information and the second set of spatial information and timing information,

wherein for each line of response (LOR) and for each position of the first axial position and the second axial position:
the corresponding spatial information includes respective positions of two crystals defining the LOR, and
the corresponding timing information includes a start time and an end time of data acquisition for each of the two crystals,

wherein the gamma-ray detector modules are disposed in at least two axial positions during a scan of the imaging subject,
wherein the start time and the end time are saved separately for each position of the gamma-ray detector modules, and
wherein the processing circuitry is further configured to reconstruct the PET image data using a list mode-based iterative reconstruction process based on each line of response (LOR) having a different start time and end time corresponding to each of the at least two axial positions, the list mode-based iterative reconstruction process being further based on a system matrix, a total number of voxels in the image, a total number of detected events, a decay correction factor, a duration correction factor, a crystal efficiency normalization factor, a geometry normalization factor, an attenuation correction factor, a scatter correction factor, and a random correction factor.

4. The positron emission tomography scanner according to claim 1 , wherein the scatter correction factor is determined by applying a decay correction and a duration correction before applying a tail fitting to the scatter correction.

5. The positron emission tomography scanner according to claim 1 , wherein the random correction factor is determined by applying a decay correction and a duration correction before applying a smoothing to the random correction.

6. The positron emission tomography scanner according to claim 1 , wherein the random correction factor is determined by determining a randoms ratio for said each LOR based on delay and primary window events, generating a new sinogram based on the determined randoms ratio, and smoothing the sinogram based on the randoms ratio.

7. The positron emission tomography scanner according to claim 1 , wherein the geometry normalization factor is determined by measuring a geometry normalization at a largest field of view of the PET scanner with the gamma-ray detector modules disposed at predetermined first positions and interpolating a geometry normalization for the gamma-ray detector modules at predetermined second positions between the predetermined first positions.

8. A positron emission tomography scanner, comprising:
a plurality of gamma-ray detector rings that form a bore through which an imaging subject is translated, a length of the bore defining an axial length of the PET scanner, the plurality of gamma-ray detector rings being movable along the axial length, the plurality of gamma-ray detector rings each including gamma-ray detector modules therein, and
processing circuitry configured to
receive PET data associated with a plurality of transaxial slices of the imaging subject, the PET data including a first set of spatial information and timing information corresponding to a first data acquisition period for the gamma-ray detector modules in a first axial position along the axial length and a second set of spatial information and timing information corresponding to a second data acquisition period for the gamma-ray detector modules in a second axial position along the axial length, and
reconstruct a PET image based on the received PET data, including the first set of spatial information and timing information and the second set of spatial information and timing information,

wherein for each line of response (LOR) and for each position of the first axial position and the second axial position:
the corresponding spatial information includes respective positions of two crystals defining the LOR, and
the corresponding timing information includes a start time and an end time of data acquisition for each of the two crystals,

wherein the gamma-ray detector modules are disposed in at least two axial positions during a scan of the imaging subjec

Assignees

• Canon Medical Systems Corp

Inventors

• Qi Wenyuan
• Burr Kent C
• Qiang Yi
• Asma Evren
• Kolthammer Jeffrey

Classifications

• G06T12/00

  Tomographic reconstruction from projections · CPC title

• G01T1/1641

  Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras · CPC title

• A61B6/54

  Control of apparatus or devices for radiation diagnosis · CPC title

• G01T1/2985

  In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); (using external radiation sources A61B6/02) · CPC title

• A61B6/4258

  for detecting non x-ray radiation, e.g. gamma radiation (A61B6/037 takes precedence) · CPC title