Abstract: Disclosed herein too is a positron emission tomography calibration system comprising a positron emission tomography scanner having a ring detector that comprises at least one bin for receiving radiation; a patient that is placed at approximately the center of the ring detector where the patient is irradiated with at least one dose of a treatment radiation beam; a crystal efficiency calibration system that performs the following: measures activity generated by the at least one defined radiation dose in the at least one bin; takes projection data of the measured activity; calculates crystal efficiency from the projection data; re-estimates the measured activity of each bin based on the calculated crystal efficiency; and calibrates the detector based on the re-estimated measured activity.

Abstract: Normalization coefficients in are computed for positron emission tomography (PET) continuous bed motion acquisition (CBM). The normalization coefficients for the lines-of-response in CBM account for the change in decay of the injected isotope over time and/or changes in velocity of the bed motion.

Abstract: Motion correction is performed in time-of-flight (TOF) positron emission tomography (PET). Rather than applying motion correction to reconstructed images or as part of reconstruction, the motion correction is applied in the projection domain of the PET data. The TOF data from the PET scan is altered to account for the motion. The TOF data is altered prior to starting reconstruction. The motion in the patient or image domain is forward projected to provide motion in the projection domain of the TOF data. The projected motion of different phases is applied to the TOF data from different phases, respectively, to create a combined dataset of motion corrected TOF data representing the patient at a reference phase. The dataset is larger (e.g., similar size from projection data dimension point of view, but contains more counts per projection data unit or is more dense) than available at one phase of the physiological cycle and is then used in reconstruction.

Abstract: A method includes overlaying a grid on a set of dynamic PET, SPECT, CT or MR data, so as to define a set of voxels defining a plurality of cluster seeds; extracting a respective time activity curve (TAC) for dynamic PET or SPECT data or time varying signals in the case of dynamic CT or MR data, for each voxel based on the data; selecting a subset of the cluster seeds defined by the grid as initial cluster centroids of a set of clusters; assigning each TAC to a respective cluster in the set of clusters; computing a respective average TAC of each cluster; generating a parametric image based on the respective average TACs for the clusters; repeating the overlaying, determining, selecting, assigning, computing, and generating; and averaging the generated parametric images.

Abstract: A process for operating a PET scanner includes acquiring, at a plurality of detector blocks of the PET scanner, emission data of gamma photons of a first energy level originating from annihilation events associated with radioactivity of a phantom in a field of view of the PET scanner. Based on the emission data, an emission block-pair scattering model is generated. The process includes acquiring counts of gamma photons of a second energy level originating from intrinsic background radiation of scintillator crystals of the detector blocks, without any phantom in the field of view, to provide blank scan data for the second energy level. A sinogram is generated based on the blank scan data for the second energy level. The emission block-pair scattering model is added to a scaled version of the sinogram to yield a composite model.

Abstract: Methods and systems for processing data for medical imaging are disclosed. The method includes obtaining a set of continuous bed motion (CBM) data from a first imaging modality. The set of CBM data includes a plurality of gating signals. A CBM normalization matrix is calculated. The CBM normalization matrix calculation includes the plurality of gating signals. An image is reconstructed from the CBM data and the CBM normalization matrix. The first imaging modality can be a PET imaging device.

Abstract: Methods and systems for processing data for medical imaging are disclosed. The method includes obtaining a set of continuous bed motion (CBM) data from a first imaging modality. The set of CBM data includes a plurality of gating signals. A CBM normalization matrix is calculated. The CBM normalization matrix calculation includes the plurality of gating signals. An image is reconstructed from the CBM data and the CBM normalization matrix. The first imaging modality can be a PET imaging device.

Abstract: Disclosed herein too is a positron emission tomography calibration system comprising a positron emission tomography scanner having a ring detector that comprises at least one bin for receiving radiation; a patient that is placed at approximately the center of the ring detector where the patient is irradiated with at least one dose of a treatment radiation beam; a crystal efficiency calibration system that performs the following: measures activity generated by the at least one defined radiation dose in the at least one bin; takes projection data of the measured activity; calculates crystal efficiency from the projection data; re-estimates the measured activity of each bin based on the calculated crystal efficiency; and calibrates the detector based on the re-estimated measured activity.

Abstract: Reconstruction in positron emission tomography is performed with partially known attenuation. A PET-CT scanner is used to generate a PET image with time of flight emission information. To limit x-ray dose while providing increased sensitivity at the ends of the CT volume in the PET image, attenuation coefficients for oblique LORs passing outside the CT volume are determined from the time of flight emission information. The attenuation coefficients for LORs within the CT volume are derived from the CT data. An objective function may be maximized for the emission distribution without reconstructing the attenuation distribution.

Abstract: A process for operating a PET scanner includes acquiring, at a plurality of detector blocks of the PET scanner, emission data of gamma photons of a first energy level originating from annihilation events associated with radioactivity of a phantom in a field of view of the PET scanner. Based on the emission data, an emission block-pair scattering model is generated. The process includes acquiring counts of gamma photons of a second energy level originating from intrinsic background radiation of scintillator crystals of the detector blocks, without any phantom in the field of view, to provide blank scan data for the second energy level. A sinogram is generated based on the blank scan data for the second energy level. The emission block-pair scattering model is added to a scaled version of the sinogram to yield a composite model.

Abstract: The DCC (Data Consistency Condition) algorithm is used in combination with MLAA (Maximum Likelihood reconstruction of Attenuation and Activity) to generate extended attenuation correction maps for nuclear medicine imaging studies. MLAA and DCC are complementary algorithms that can be used to determine the accuracy of the mu-map based on PET data. MLAA helps to estimate the mu-values based on the biodistribution of the tracer while DCC checks if the consistency conditions are met for a given mu-map. These methods are combined to get a better estimation of the mu-values. In gated MR/PET cardiac studies, the PET data is framed into multiple gates and a series of MR based mu-maps corresponding to each gate is generated. The PET data from all gates is combined. Once the extended mu-map is generated the central region is replaced with the MR based mu-map corresponding to that particular gate.

Abstract: Random sinogram variance is reduced in continuous bed motion acquisition. The randoms are modeled as a product of transverse singles efficiencies. The random sinogram is assumed to be a smooth function in the axial direction, collapsing the parameterization for estimating the transverse singles efficiencies into a single, conceptual ring. By solving the product, the mean random values are used to smooth the randoms in image reconstruction with less noise and artifacts.

Abstract: Reconstruction in positron emission tomography is performed with partially known attenuation. A PET-CT scanner is used to generate a PET image with time of flight emission information. To limit x-ray dose while providing increased sensitivity at the ends of the CT volume in the PET image, attenuation coefficients for oblique LORs passing outside the CT volume are determined from the time of flight emission information. The attenuation coefficients for LORs within the CT volume are derived from the CT data. An objective function may be maximized for the emission distribution without reconstructing the attenuation distribution.

Abstract: Methods, and systems therefrom, for generating images from time of flight (TOF) data associated with a scan of at least one object using a positron emission tomography system are provided. The method includes providing initial values for an activity image to yield a current activity image. The method also includes estimating initial values for an attenuation map (?-map) image based on the TOF data to yield a current ?-map image. The method further includes repeating, until at least one termination condition is met, the steps of updating the current activity image based on at least the current ?-map and a first update algorithm and updating the current ?-map image based on at least on the updated activity image and a second update algorithm. The method also includes outputting an image of the at least one object based on the current ?-map and the current activity image.

Abstract: Normalization coefficients in are computed for positron emission tomography (PET) continuous bed motion acquisition (CBM). The normalization coefficients for the lines-of-response in CBM account for the change in decay of the injected isotope over time and/or changes in velocity of the bed motion.

Abstract: Random sinogram variance is reduced in continuous bed motion acquisition. The randoms are modeled as a product of transverse singles efficiencies. The random sinogram is assumed to be a smooth function in the axial direction, collapsing the parameterization for estimating the transverse singles efficiencies into a single, conceptual ring. By solving the product, the mean random values are used to smooth the randoms in image reconstruction with less noise and artifacts.

Abstract: The DCC (Data Consistency Condition) algorithm is used in combination with MLAA (Maximum Likelihood reconstruction of Attenuation and Activity) to generate extended attenuation correction maps for nuclear medicine imaging studies. MLAA and DCC are complementary algorithms that can be used to determine the accuracy of the mu-map based on PET data. MLAA helps to estimate the mu-values based on the biodistribution of the tracer while DCC checks if the consistency conditions are met for a given mu-map. These methods are combined to get a better estimation of the mu-values. In gated MR/PET cardiac studies, the PET data is framed into multiple gates and a series of MR based mu-maps corresponding to each gate is generated. The PET data from all gates is combined. Once the extended mu-map is generated the central region is replaced with the MR based mu-map corresponding to that particular gate.

Abstract: Point spread function (PSF) radial filtering in a line of response space. Modeling a radial component, R, of a point spread filter as a function of at least a radial projection index ?, a radial image space coordinate r, and an azimuth ?. The index ? is characterized by an asymmetrical Gaussian distribution having where ?left(r) and ?right(r) derived from point source measurements, and an adjustment ?J(r, ?) estimated from point source sinogram by Josephs' projector.

Abstract: A method and system is provided for performing medical imaging. The method and system includes at least one radiation detector to detect radiation from a subject, and an image processor which determines attenuation paths for an image point, groups substantially similar attenuation path lengths for the same image point to form a modified subset group, and processing image data using the modified subset group in order to provide a reconstructed image substantially similar to an original image.

Abstract: Methods, and systems therefrom, for generating images from time of flight (TOF) data associated with a scan of at least one object using a positron emission tomography system are provided. The method includes providing initial values for an activity image to yield a current activity image. The method also includes estimating initial values for an attenuation map (?-map) image based on the TOF data to yield a current ?-map image. The method further includes repeating, until at least one termination condition is met, the steps of updating the current activity image based on at least the current ?-map and a first update algorithm and updating the current ?-map image based on at least on the updated activity image and a second update algorithm. The method also includes outputting an image of the at least one object based on the current ?-map and the current activity image.