Photon interaction characteristics from a subset of pixels
Inventors
Harris, Brian William • Tomita, Hidefumi
Assignees
Publication Number
US-11255984-B2
Publication Date
2022-02-22
Expiration Date
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Abstract
One embodiment provides a method, including: receiving a photon interaction occurring within a photon detector pixel array, wherein the photon detector pixel array comprises a plurality of pixels; determining a photoelectron cloud generated from the photon interaction, wherein the photon detector pixel array comprises an electric field, wherein an electrostatic repulsive force disperses a photon to the photoelectron cloud; identifying a subset of the plurality of pixels associated with the photon interaction, wherein each of the subset of the plurality of pixels corresponds to pixels activated by the photo electron cloud, wherein the subset of the plurality of pixels comprise a central pixel and a plurality of neighboring pixels, wherein the central pixel comprises the pixel having the highest amplitude response to the photon interaction; and determining, from the photoelectron cloud, a characteristic of the photon interaction, wherein the characteristic comprises at least one of: time, position, and energy of the interaction. Other aspects are described and claimed.
Core Innovation
One embodiment provides a method, device, and product that receive a photon interaction occurring within a photon detector pixel array comprising a plurality of pixels; determine a photoelectron cloud generated from the photon interaction where the photon detector pixel array comprises an electric field and an electrostatic repulsive force disperses a photon to the photoelectron cloud; identify a subset of the plurality of pixels associated with the photon interaction comprising a central pixel and a plurality of neighboring pixels where the central pixel comprises the pixel having the highest amplitude response to the photon interaction; and determine, from the photoelectron cloud, a characteristic of the photon interaction comprising at least one of time, position, and energy of the interaction.
The background describes a problem in which pixelated semiconductor detector arrays exhibit a distortion of the energy spectrum of individual pixels where some counts are recorded with a lower energy than the photopeak because of hole carrier trapping or charge sharing with neighbor pixels, causing counts in the lower energy spectral tail to be excluded from image formation and making the gamma camera apparently less efficient; additionally current systems may have difficulty in attributing detected charges to the correct interaction upon a pixel or subset of pixels such that loss of data from neighboring pixels or resolution within a pixel diminishes imaging resolution and can decrease efficiency in medical care.
The embodiments provide a technical improvement by capturing information from a central anode pixel and neighboring anode pixels and by using only the positive and negative peak amplitudes of anode pixel signals, without requiring cathode signals, to determine interaction characteristics; using these values the system can identify sub-pixel resolution, recombine shared-events, and correct characteristics regarding an interaction to improve energy resolution, which the patent states may be important for medical imaging and may enable lower patient dosing, reduced exam durations, and lower costs.
Claims Coverage
Independent claims: 1, 11, and 20. The following 5 inventive features are extracted from the independent claims.
Receiving a photon interaction within a photon detector pixel array
A step or code to receive a photon interaction occurring within a photon detector pixel array comprising a plurality of pixels.
Determining a photoelectron cloud dispersed by electrostatic repulsion in an electric field
A step or code to determine a photoelectron cloud generated from the photon interaction where the photon detector pixel array comprises an electric field and an electrostatic repulsive force disperses a photon to the photoelectron cloud.
Identifying a subset of pixels comprising a central pixel and neighboring pixels with central pixel having highest amplitude response
A step or code to identify a subset of the plurality of pixels associated with the photon interaction, wherein each of the subset corresponds to pixels activated by the photoelectron cloud and the subset comprises a central pixel and a plurality of neighboring pixels, the central pixel having the highest amplitude response to the photon interaction.
Determining interaction characteristics (time, position, energy) by adding correction factors based on energy ratios
A step or code to determine, from the photoelectron cloud, a characteristic of the photon interaction comprising at least one of time, position, and energy of the interaction, wherein the determining comprises adding a correction factor from each of the plurality of pixels to the central pixel based upon a ratio of energy of each of the plurality of pixels.
Implementing the method in a device or product with processor, memory, or stored code
Claimed apparatus and product embodiments comprising a photon detector pixel array and a processor with a memory storing instructions, or a non-transitory storage device storing code, executable to perform the receiving, determining, identifying, and determining steps.
The independent claims collectively cover (1) receiving photon interactions in a pixelated detector, (2) determining a photoelectron cloud under an electric field with electrostatic repulsion, (3) identifying a subset of pixels including a central pixel and neighboring pixels where the central pixel has the highest amplitude, (4) determining interaction characteristics (time, position, energy) with a correction factor added to the central pixel based on energy ratios, and (5) implementations as an apparatus with processor/memory or as stored code on a non-transitory storage device.
Stated Advantages
Provides sub-pixelation resolution and higher spatial, temporal, and energy resolution.
Does not require cathode signals; uses only positive and negative peak amplitudes of anode pixel signals, simplifying determination of interaction characteristics.
Recombines shared-event information to correct charge sharing and hole trapping spectral tail problems, improving energy resolution.
May enable lower patient dosing, reduced exam or procedure durations, and lower costs in medical imaging.
Enables more accurate imaging and can result in less device down-time.
Documented Applications
Nuclear medicine imaging applications including gamma cameras and pixelated detectors for PET and SPECT imaging.
X-ray imaging systems and x-ray computed tomography (CT) imaging systems, including cameras formed from pixelated detectors.
Security screening applications, including airport security checkpoints and baggage screening using multiple x-ray sources and pixelated photon detector arrays.
Hand-held devices for use by first responders, security, or assessment teams.
Manufacturing and environmental assessment uses where imaging devices may be utilized.
Integration into imaging systems with rotating or stationary gantries and rotors configured to support one or more pixelated cameras.
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