US 6,490,476 B1Granted

Combined PET and X-ray CT tomograph and method for using same

AssigneeCTI PET Systems, Inc.

InventorsDavid W. Townsend, Ronald Nutt

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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.

Claims16

Dependent claims

A method for acquiring PET and CT images sequentially within a combined PET and X-Ray CT tomograph, the combined PET and X-Ray CT tomograph including a CT scanner having a patient gantry, a PET scanner having a patient gantry, a patient support for supporting a patient positioned within each said CT scanner patient gantry and said PET scanner patient gantry, and a display device, said method comprising the steps of:

introducing a tracer into a patient for detection by said combined PET and X-Ray CT tomograph;
waiting for an uptake period to expire, the tracer being circulated through and absorbed by the patient during said uptake period;
placing the patient on said patient support;
moving said patient support to position the patient within said CT scanner patient gantry such that a selected region to be studied is within a field of view of said CT scanner;
acquiring a CT image of the selected region of the patient;
correcting said CT image for artifacts due to field of view truncation, said step of correcting said CT image includes the steps of:
obtaining a non-corrected PET image, said non-corrected PET image reconstructed without attenuation correction;
determining a boundary of a truncated portion of the selected region of the patient using said non-corrected PET image;
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
adding said volume to said CT image;
reconstructing said CT image to achieve a reconstructed CT image;
generating attenuation correction factors from said reconstructed CT image;
moving said patient support to position the patient within said PET scanner patient gantry such that the selected region to be studied is within a field of view of said PET scanner;
acquiring a PET image of the selected region of the patient;
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;
and
reconstructing said attenuation-corrected PET image to achieve a reconstructed PET image.

16 more elements

A method for acquiring PET and CT images sequentially within a combined PET and X-Ray CT tomograph, the combined PET and X-Ray CT tomograph including a patient gantry for use with both a CT scanner and a PET scanner, a patient support for supporting a patient positioned within said patient gantry, and a display device, said method comprising the steps of:

introducing a tracer into a patient for detection by said combined PET and X-Ray CT tomograph;
waiting for an uptake period to expire, the tracer being circulated through and absorbed by the patient during said uptake period;
placing the patient on said patient support;
moving said patient support to position the patient within said patient gantry such that a selected region to be studied is within a field of view of said CT scanner;
acquiring a CT image of the selected region of the patient;
correcting said CT image for artifacts due to field of view truncation, said step of correcting said CT image includes the steps of:
obtaining a non-corrected PET image, said non-corrected PET image reconstructed without attenuation correction;
determining a boundary of a truncated portion of the selected region of the patient using said non-corrected PET image;
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
adding said volume to said CT image;
reconstructing said CT image to achieve a reconstructed CT image;
generating attenuation correction factors from said reconstructed CT image;
moving said patient support to position the patient within said patient gantry such that the selected region to be studied is within a field of view of said PET scanner;
acquiring a PET image of the selected region of the patient;
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;
and
reconstructing said attenuation-corrected PET image to achieve a reconstructed PET image.

16 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/685,222Filed 10 Oct 2000 · us provisional application
Priority: 14 Oct 1999
Granted: 3 Dec 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

A61B 6/482
Diagnostic techniques: involving multiple energy imaging
A61B 6/032
Computed tomography [CT]: transmission computed tomography [CT]
A61B 6/037
Computed tomography [CT]: emission tomography
A61B 6/463
Displaying means of special interest: characterised by displaying multiple images or images and diagnostic data on one display