Combined PET and X-ray CT tomograph

• US 6,631,284 B2
• Filed: 06/12/2002
• Issued: 10/07/2003
• Est. Priority Date: 10/14/1999
• Status: Active Grant

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: CTI PET Systems, Inc. (Siemens AG)
• Inventors: Nutt, Ronald, Townsend, David W.
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US10/167,837
• Publication Number:
  US 20030004405A1
• Time in Patent Office: 482 Days
• Field of Search: 600/411, 600/427, 600/431, 600/436, 378/4, 378/21, 378/209, 250/363.03, 250/363.04
• US Class Current: 600/427
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/037 Emission tomography
• CPC Class Codes: A61B 6/405 Source units specially adapted to modify characteristics of the beam during the data acquisition process A61B6/4021, A61B6/4035 take precedence
• CPC Class Codes: A61B 6/4488 Means for cooling A61B6/045 takes precedence
• CPC Class Codes: A61B 6/463 characterised by displaying multiple images or images and diagnostic data on one display
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/5235 combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G01T 1/1611 using both transmission and emission sources sequentially SPECT imaging G01T1/1642; PET imaging G01T1/2985; detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects G01V5/20
• CPC Class Codes: G01T 1/2985 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

Abstract

A combined PET and X-Ray CT tomograph for acquiring CT and PET images sequentially in a single device, overcoming alignment problems due to internal organ movement, variations in scanner bed profile, and positioning of the patient for the scan. In order to achieve good signal-to-noise (SNR) for imaging any region of the body, an improvement to both the CT-based attenuation correction procedure and the uniformity of the noise structure in the PET emission scan is provided. The PET/CT scanner includes an X-ray CT and two arrays of PET detectors mounted on a single support within the same gantry, and rotate the support to acquire a full projection data set for both imaging modalities. The tomograph acquires functional and anatomical images which are accurately co-registered, without the use of external markers or internal landmarks.

Claims

1. A combined positron emission tomography (PET) and X-Ray computerized tomography (CT) tomograph for acquiring PET and CT images sequentially in a single device, said combined PET and X-Ray CT tomograph comprising:

a CT scanner having a patient gantry, said CT scanner including a plurality of detectors mounted on a rotating support, said CT scanner being provided for acquiring a CT image;

a PET scanner having a patient gantry separate from said CT scanner patient gantry, said PET scanner including a plurality of detectors, said PET scanner being provided for acquiring a PET image;

a patient support for supporting a patient positioned within each of said CT scanner patient gantry and said PET scanner patient gantry, said patient support being movable axially within each of said CT scanner patient gantry and said PET scanner patient gantry;

a processor for correcting said CT image for artifacts due to field of view truncation, for reconstructing said CT image to achieve a reconstructed CT image, for generating attenuation correction factors from said reconstructed CT image, for correcting said PET image for scatter to achieve a scatter-corrected PET image, applying said attenuation correction factors to said scatter-corrected PET image to achieve an attenuation-corrected PET image, for reconstructing said attenuation-corrected PET image to achieve a reconstructed PET image, and for fusing the reconstructed CT image and the reconstructed PET image to achieve a fused PET/CT image, wherein said processor corrects said CT image for artifacts by obtaining a non-corrected PET image reconstructed without attenuation correction, by determining a boundary of a truncated portion of a selected region of the patient using said non-corrected PET image, by estimating a volume within said boundary of the truncated portion of the selected region using an average linear attenuation coefficient for the truncated portion of the selected region and by adding said volume to said CT image; and

a display device for displaying at least one of the reconstructed CT image, the reconstructed PET image and the fused PET/CT image generated by said combined PET and X-Ray CT tomograph.

2. The combined PET and X-Ray CT tomograph of claim 1 wherein said CT scanner patient gantry is fixed relative to said PET scanner patient gantry, said patient support being movable between said CT scanner patient gantry and said PET scanner patient gantry.

3. The combined PET and X-Ray CT tomograph of claim 1 wherein at least one of said CT scanner patient gantry and said PET scanner patient gantry is movable with respect the other, and wherein said patient support is movable between said CT scanner patient gantry and said PET scanner patient gantry.

4. A combined positron emission tomography (PET) and X-Ray computerized tomography (CT) tomograph for acquiring PET and CT images sequentially in a single device, said combined PET and X-Ray CT tomograph comprising:

a CT scanner including a plurality of detectors mounted on a rotating support, said CT scanner being provided for acquiring a CT image;

a PET scanner including a plurality of detectors, said PET scanner being provided for acquiring a PET image, said PET scanner plurality of detectors being mounted on said rotating support in fixed relationship to said CT scanner plurality of detectors;

a patient gantry for use with both said CT scanner and said PET scanner;

a patient support for supporting a patient positioned within said patient gantry, said patient support being movable axially within said patient gantry;

a processor for correcting said CT image for artifacts due to field of view truncation, for reconstructing said CT image to achieve a reconstructed CT image, for generating attenuation correction factors from said reconstructed CT image, for correcting said PET image for scatter to achieve a scatter-corrected PET image, applying said attenuation correction factors to said scatter-corrected PET image to achieve an attenuation-corrected PET image, for reconstructing said attenuation-corrected PET image to achieve a reconstructed PET image, and for fusing the reconstructed CT image and the reconstructed PET image to achieve a fused PET/CT image, wherein said processor corrects said CT image for artifacts by obtaining a non-corrected PET image reconstructed without attenuation correction, by determining a boundary of a truncated portion of a selected region of the patient using said non-corrected PET image, by estimating a volume within said boundary of the truncated portion of the selected region using an average linear attenuation coefficient for the truncated portion of the selected region and by adding said volume to said CT image; and

a display device for displaying at least one of the reconstructed CT image, the reconstructed PET image and the fused PET/CT image generated by said combined PET and X-Ray CT tomograph.