Supplemental transmission information for attenuation correction in positron emission tomography imaging

摘要

Supplemental transmission information is used in PET imaging with a hybrid PET/MR system. The magnetic field of the MR portion is used to direct positrons from one or more sources outside or inside the PET field of view to within the PET field of view. An oblique target or targets create an annihilation source within the PET field of view from the positron beam or beams. The resulting radiation may be detected. In combination with measurements made with the sources shielded (e.g., no positron beam-target annihilation sources), the attenuation or other characteristics outside the uniform region of the MR field of view is determined, such as calculating attenuation of arms of a patient for attenuation correction in PET imaging.

主权项

1. A method for attenuation correction for positron emission tomography (PET) in a combined PET and magnetic resonance (MR) imaging system, the method comprising:
generating, with a positron source in a magnetic field, a positron beam extending into a field of view of PET detectors of the combined PET and MR system; intersecting the positron beam with a target within the field of view of the PET detectors; detecting, with the PET detectors, gamma radiation resulting from the intersection of the positron beam with the target; determining attenuation correction factors as a function of the detected gamma radiation; retracting the positron source into a shield; and detecting, with the PET detectors, gamma radiation while the positron source is retracted into the shield; wherein determining comprises subtracting data representing the gamma radiation detected while the positron source is retracted from data representing the gamma radiation detected while the target intersects the positron beam.