Patent ID: 6490476
Filing Date: 2002-12-03
Classification: A61B,G01T

Abstract:
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.