PET Detector Depth of Interaction Determination
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Solution Overview
Problem
Conventional PET scanners experience a progressive reduction in spatial resolution with increased distance from the center of their field of view due to uncertainty in assigning lines of response (LOR) to detected coincident events, leading to non-uniform resolution across the field of view.
Innovation Solution
A PET detector system comprising a crystal array with a single-end read-out structure and optical separators, where a photon-sensor array is optically coupled to the crystal array, allowing for accurate determination of the depth of interaction (DOI) within the crystal elements, thereby improving LOR assignment and resolution uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PET scanners use standard detector modules without depth information, then the device complexity is low, but the spatial resolution deteriorates with increased distance from the center of field of view
Solution Approach 1:
The patent introduces depth of interaction (DOI) information as an additional dimension to the conventional 2D detector readout. By determining the depth position of photon interactions within crystal elements and incorporating this z-dimension information into the detection system, the patent achieves uniform spatial resolution across the entire field of view, effectively transforming the detection from a planar to a volumetric measurement approach.
Solution Approach 2:
The patent segments the detector crystal elements into multiple depth sections and uses multiple photon sensors to readout from different ends. This segmentation allows independent measurement of light photons from different depth regions, enabling accurate DOI determination and improving spatial resolution without requiring a complete redesign of the entire detector system.
2Measurement precision
If multiple photon sensors are coupled to both ends of crystal elements for DOI determination, then the measurement precision of interaction position is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges multiple crystal elements that share common readout electronics into detector modules. By combining several crystal elements with identical photodetector readout circuits, the patent reduces the number of individual readout channels required and simplifies the manufacturing process while still enabling DOI determination through the shared sensor array.
Solution Approach 2:
The patent designs detector modules where the same photon sensors serve multiple functions: detecting light photons from different crystal elements and simultaneously providing depth of interaction information. This multi-functionality reduces the overall component count and simplifies the detector architecture compared to dedicated DOI measurement systems.
3Area of stationary object
If detector modules are located far from the central axis to expand field of view coverage, then the area of coverage is improved, but the spatial resolution deteriorates due to increased LOR assignment uncertainty
Solution Approach 1:
The patent introduces depth of interaction information as an intermediary parameter that mediates between the detector position and the line of response assignment. By incorporating DOI measurements, the system can more accurately determine the three-dimensional position of photon interactions, which improves LOR assignment accuracy even for detector modules located far from the central axis, thereby maintaining high measurement precision across the expanded field of view.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution enhances imaging resolution by accurately determining the position and depth of photon interactions within the PET detector, leading to more uniform resolution across the field of view and improved accuracy in assigning LORs.
Implementation Method 1
The tracer may undergo positron emission decay and emit a positron. The positron may annihilate with an electron, generating a pair of annihilation photons (e.g., gamma photons) that move in approximately opposite directions. The annihilation photons may be absorbed by a plurality of crystal elements (e.g., arranged in the form of one or more rings) that create bursts of optical photons
Implementation Method 2
The annihilation photons may be absorbed by a plurality of crystal elements (e.g., arranged in the form of one or more rings) that create bursts of optical photons (e.g., visible light photons) that, in turn, may be detected by photodetectors
Data Source
AI summary
The present disclosure relates to devices, systems and methods for determining a position of a photon gamma interaction in a PET detector. The PET detector may include a crystal array and a single-end read-out structure. The single-end read-out structure may include a photon-sensor array optically coupled with the crystal array. The crystal array may include a plurality of crystal elements arranged along a first direction and a second direction. The crystal elements may form a plurality of crystal groups along the first direction. The PET detector may further include a plurality of optical separators of the same or different lengths configured to control light transmission in the PET detector. The position of the photon gamma interaction in a crystal group may be determined based on output information of the photon-sensor array optically coupled with the crystal group.