Leland Stanford Junior University

University of California

Koninklijke Philips Corporation N.v.

University of Illinois

Craig Steven Levin

Peter D Olcott

Garry Chinn

Guillem Pratx

Farhad Taghibakhsh

Alexander Mihlin

Mark A Horowitz

Sanjiv Sam Gambhir

Jaeha Kim

Jin Zhang

Henry Meyer Daghighian

Sven Prevrhal

Jingyu Cui

Ewout Van Den Berg

Edward J Hoffman

Emmanuel J Candes

Virginia Spanoudaki

Ruud Vinke

Angela M Foudray

James Matteson

Frances W Y Lau

Hwang Ho Choi

Shiva Abbaszadeh

Carlos Alberto Sing-Long Collao

A method of PET image reconstruction is provided that includes obtaining intra-patient tissue activity distribution and photon attenuation map data using a PET/MRI scanner, and implementing a Maximum Likelihood Expectation Maximization (MLEM) method in conjunction with a specific set of latent random variables, using an appropriately programmed computer and graphics processing unit, wherein the set of latent random variables comprises the numbers of photon pairs emitted from an electron-positron annihilation inside a voxel that arrive into two given voxels along a Line of Response (LOR), where the set of latent random variables results in a separable joint emission activity and a photon attenuation distribution likelihood function.

Simultaneous attenuation and activity reconstruction for positron emission tomography

Measuring in a first semiconductor crystal two anode channels and two cathode channels and measuring in a second semiconductor crystal one anode channel and one cathode channel; responsive to an energy of a sum of the two anode channels being within an energy window and an energy of the one anode channel being within the energy window: separating the two anode channels and the two cathode channels into combinations of anode-cathode channel pairs; for each of the anode-cathode channel pairs, determining a respective direction difference angle, each respective direction difference angle being determined via use of the one anode channel and one cathode channel; determining a determined one of the direction difference angles that has a smallest value; and setting as an initial interaction position of a photon a selected one of the anode-cathode channel pairs that corresponds to the determined direction difference angle. Additional embodiments are disclosed.

Method and system for increasing radiation sensitivity in semiconductor detectors

We provide improved maximum likelihood expectation maximization (MLEM) joint estimation of emission activity and photon attenuation from positron emission tomography (PET) data. Lines of response (LOR) are divided along their length into cells having equal length. MLEM computations assume all intersections between LOR cells and voxels have an intersection length of the LOR cell length. This way of discretizing the problem has the significant advantage of leading to MLEM update equations that have a closed form exact solution, which is important for fast, accurate and robust estimation.

Statistical data acquisition model for GPU based MLEM joint estimation of tissue activity distribution and photon attenuation map from PET data

A method for extracting photon depth-of-interaction of an incident photon in a crystal with a reflective coating optically coupled to all sides of the crystal, except for an opening, wherein a photodetector is optically coupled to the opening. A pulse shape of a photodetector output as a result of detection of scintillation photons from the crystal generated by the incident photon is measured, wherein the reflective coating optically coupled to all sides of the crystal, except for an opening optically coupled to the photodetector reflects the scintillation photons passing to all sides of the crystal, except for the opening optically coupled to the photodetector. The pulse shape is used to determine photon depth-of-interaction within the crystal.

Method to extract photon depth-of interaction and arrival time within a positron emission tomography detector

A detector is provided. A plurality of scintillation crystals is provided, where each scintillation crystal has a width, and wherein a first plurality of scintillation crystals is placed adjacent to each other so that first surfaces of the first plurality of scintillation crystals form a first rectangular surface. A reflective coating is formed over the first rectangular surface with an open region grid pattern, wherein each open region forms a space wherein each space has a width equal to the width of a scintillation crystal of the plurality of crystals. A plurality of photodetectors is provided, wherein each photodetector is placed over a space, wherein the photodetector has a width greater than the width of the space over which the photodetector is placed. At least one electronic readout is electrically connected to the plurality of photodetectors.

Dedicated cardiac PET

Simultaneous dual-isotope positron emission tomography (PET) is used to improve disease evaluation. Two distinct molecular probes are simultaneously provided to the imaging target. One of the probes is labeled with a radionuclide that emits positrons to provide double coincidence events in PET. The other probe is labeled with a radionuclide that emits positrons+prompt gammas to provide triple coincidence events in PET. One of the probes is a metabolic probe, and the other probe is a selective probe that includes a ligand or antibody that is biologically responsive to receptor/antigen status. A PET system is employed that can provide simultaneous double coincidence and triple coincidence PET images. The resulting images provide simultaneous metabolic imaging and receptor/antigen imaging. Applications include disease evaluation, such as cancer staging (e.g., for breast cancer, prostate cancer, etc.).

Dual-isotope position emitting tomography for disease evaluation

An integrated circuit in a PET imaging system with a plurality of photo detectors is provided. A plurality of differential transimpedance amplifiers with differential inputs and differential outputs is provided, wherein differential inputs for each differential transimpedance amplifier of the plurality of differential transimpedance amplifiers are electrically connected to a photodetector. A plurality of level crossing analog-to-digital converters is provided wherein differential inputs for each level crossing analog-to-digital converter of the plurality of level crossing analog-to-digital converters are electrically connected to differential outputs of a differential transimpedance amplifier, wherein each level crossing analog-to-digital converter of the plurality of level crossing analog-to-digital converters, comprises a plurality of differential comparators with differential inputs and differential threshold inputs, wherein the differential inputs are electrically connected to the output of the differential outputs of the differential transimpedance amplifier electrically connected to the level crossing analog-to-digital converter and a clock.

Time-based digitizer for PET photodetector

A method for providing an image from a device with a plurality of sensors and a plurality of time to digital converters (TDC) is provided. Data signals are generated by some of the plurality of sensors, wherein each sensor of the plurality of sensors provides output in parallel to more than one TDC of the plurality of TDCs and wherein each TDC of the plurality of TDCs receives in parallel input from more than one sensor of the plurality of sensors and where a binary matrix indicates which sensors are connected to which TDC. The data signals are transmitted from the sensors to the TDCs. TDC signals are generated from the data signals. Group testing is used to decode the TDC signals based on the binary matrix.

Digital multiplexing readout for sparse signals on imaging arrays

Embodiments of the invention provide a high energy photon detector. A first scintillation crystal is provided. A first plurality of photosensors is on a first face of the first scintillation crystal, wherein the first plurality is at least two. A second scintillation crystal is provided. A second plurality of photosensors is on a first face of the second scintillation crystal, wherein the second plurality is at least two. An optical coupling interface is between a second face of the first scintillation crystal and a second face of the second scintillation crystal, wherein the optical coupling interface provides an optical transmission between the first scintillation crystal and the second scintillation crystal, so that the distribution of scintillation light created in one crystal is allowed to spread into the second crystal.

Optical coupling technique for contiguous monolithic scintillation crystal detectors

Line segments are classified according to orientation to improve list mode reconstruction of tomography data using graphics processing units (GPUs). The new approach addresses challenges which include compute thread divergence and random memory access by exploiting GPU capabilities such as shared memory and atomic operations. The benefits of the GPU implementation are compared with a reference CPU-based code. When applied to positron emission tomography (PET) image reconstruction, the GPU implementation is 43&#xd7; faster, and images are virtually identical. In particular, the deviation between the GPU and the CPU implementation is less than 0.08% (RMS) after five iterations of the reconstruction algorithm, which is of negligible consequence in typical clinical applications.

Shift-varying line projection using graphics hardware

Positron emission tomography (PET) systems suitable for use with dirty (positron+prompt gamma) emitters are provided. One or more prompt gamma detectors are added to the PET system, where the prompt gamma detectors are responsive to the prompt gammas provided by the dirty emitter, but are not responsive to 511 keV annihilation photons. The prompt gamma detectors can surround the imaging PET detector array and/or be disposed as end caps relative to a generally cylindrical PET detector array. The prompt gamma detectors need not provide spatial resolution, because coincidence events in the PET detector array are classified as 2-photon or 3-photon events depending on whether or not there is a time-coincident signal from the prompt gamma detectors. One application of this approach is dual isotope PET where distinct tracers labeled with clean and dirty positron emitters are simultaneously imaged.

Methods and systems for increasing the sensitivity of simultaneous multi-isotope positron emission tomography

A method for extracting photon depth of interaction information in a positron emission tomography system is provided. A pulse is detected in a photodetector. A height of the pulse is measured. A determination of whether the pulse height is within a set range is made. Photon depth of interaction is extracted from the pulse height. An energy of interaction is calculated from the pulse height and calibration data. The extracted photon depth and calculated energy spectrum are used in image reconstruction.

High resolution positron emission tomography

An apparatus for detecting ionizing radiation from a source. A detector is disposed relative to the source to receive the ionizing radiation. The ionizing radiation causes ionization and/or excitation in the detector, wherein an optical property of the detector is altered in response to the ionization and/or excitation. A source of coherent probing light is disposed relative to the detector to probe the detector. The detector outputs the probing light, wherein the output light is modulated in response to the altered optical property. A receiver receives the output light and detects modulation in the output light.

Methods and systems for radiation detection

A front end for an imaging system. The front end comprises at least one magnetically-insensitive high-energy photon detector and an interface for converting an output of the at least one high-energy photon detector to an optical signal and transmitting the optical signal. A receiver is optically coupled to the interface to receive the optical signal and convert the optical signal into a voltage signal.

Optically coupled readout front-end for imaging system

Compressed sensing (CS) estimation approaches rely on a priori sparsity to significantly reduce the number of samples needed to provide high sampling fidelity, relative to the normal Shannon-Nyquist limit. Accordingly, CS approaches are of considerable interest for detector multiplexing in applications which have inherently sparse signals (e.g., the two correlated photon detection events in PET imaging). However, CS approaches also tend to fare poorly in the presence of noise, which has limited their applicability in practice. In this work, we show that CS estimation can be used to provide an estimate of the support of an image. This estimated support is then used as a constraint for maximum likelihood image reconstruction. This approach has robust noise performance and provides high reconstruction fidelity.

Growing community of inventors

Palo Alto, CA, United States of America

Craig Steven Levin