摘要:
Methods and systems for reconstructing a nuclear medical image from time-of-flight (TOF) positron emission tomography (PET) imaging data are disclosed. Measured three-dimensional (3D) TOF-PET data, including direct two-dimensional (2D) projections and oblique 3D projection data, are acquired from a PET scanner. A model 3D image is preset, a modeled 2D TOF sinogram is generated from the model 3D image, and a modeled 3D TOF sinogram is generated from the 2D TOF sinogram based on an exact inverse rebinning relation in Fourier space. The model 3D image is corrected based on the 3D TOF sinogram and is provided as the reconstructed nuclear medical image. Techniques disclosed herein are useful for facilitating efficient medical imaging, e.g., for diagnosis of various bodily conditions.
摘要:
The use of the ordinary Poisson iterative reconstruction algorithm in PET requires the estimation of expected random coincidences. In a clinical environment, random coincidences are often acquired with a delayed coincidence technique, and expected randoms are estimated through variance reduction (VR) of measured delayed coincidences. In this paper we present iterative VR algorithms for random compressed sinograms, when previously known methods are not applicable. Iterative methods have the advantage of easy adaptation to any acquisition geometry and of allowing the estimation of singles rates at the crystal level when the number of crystals is relatively small. Two types of sinogram compression are considered: axial (span) rebinning and transaxial mashing. A monotonic sequential coordinate descent algorithm, which optimizes the Least Squares objective function, is investigated. A simultaneous update algorithm, which possesses the advantage of easy parallelization, is also derived for both cases of the Least Squares and Poisson Likelihood objective function.
摘要:
A method of constructing a non-uniform attenuation map (460) of a subject for use in image reconstruction of SPECT data is provided. It includes collecting a population of a priori transmission images and storing them in an a priori image memory (400). The transmission images not of the subject. Next, a cross-correlation matrix (410) is generated from the population of transmission images. The eigenvectors (420) of the cross-correlation matrix (410) are calculated. A set of orthonormal basis vectors (430) is generated from the eigenvectors (420). A linear combination of the basis vectors (420) is constructed (440), and coefficients for the basis vectors are determined (450) such that the linear combination thereof defines the non-uniform attenuation map (460).