Depth-of-Interaction PET Scanner with Embedded Shielding
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Solution Overview
Problem
Current positron emission tomography (PET) scanners face challenges in achieving high sensitivity and cost-effectiveness due to the need for extensive room shielding and depth-of-interaction blurring, which affects image quality and scan time.
Innovation Solution
The design incorporates a depth-of-interaction scanner with a plurality of scintillation crystals and photodetectors arranged in a grid pattern for improved depth resolution and time-of-flight measurement, along with an optically transparent high energy photon shield for reduced shielding costs and improved patient access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If extensive room shielding is used to protect against high energy photons, then radiation safety is improved, but cost and device complexity increase
Solution Approach 1:
The patent extracts the shielding function from the room structure and integrates it directly into the scanner assembly. The lead-lined shielding is attached to the scanner's support structure, creating a self-contained shielded enclosure that moves with the scanner, thereby reducing the need for extensive permanent room shielding.
Solution Approach 2:
The shielding structure is nested within the scanner assembly, with lead-lined barriers integrated into the support structure and positioning mechanisms. This nested configuration provides radiation protection while minimizing the overall footprint and complexity of the shielding system.
2Measurement precision
If depth-of-interaction detection is implemented, then image quality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent measures depth-of-interaction in a dimensional direction perpendicular to the photodetector surface, rather than requiring precise lateral positioning. By detecting the depth coordinate along the photon penetration path, the system achieves improved image quality without demanding extremely tight manufacturing tolerances for lateral crystal positioning.
Solution Approach 2:
The patent introduces an intermediate measurement approach using the ratio of signals from multiple photodetectors to infer depth-of-interaction. This intermediary calculation method converts complex three-dimensional positioning requirements into a ratio-based measurement that is more tolerant of manufacturing variations.
3Use of energy by moving object
If photodetectors with width greater than space width are used, then light collection efficiency is improved, but cross-talk between adjacent crystals increases
Solution Approach 1:
The patent applies different properties to different regions of the photodetector array. Each photodetector is assigned to read out specific scintillation crystals based on local geometric relationships, creating a customized readout mapping that maximizes light collection for each crystal while preventing cross-talk through selective signal assignment.
Solution Approach 2:
The patent changes the operational parameters of the photodetectors by adjusting their readout assignments and signal processing characteristics. By dynamically controlling which photodetector reads which crystal based on geometric parameters, the system optimizes light collection efficiency while suppressing cross-talk through parameter-based signal differentiation.
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
This configuration enhances image quality by reducing depth-of-interaction blurring and transit time variance, while minimizing shielding costs and claustrophobic effects, resulting in improved sensitivity and efficiency in PET scans.
Implementation Method 1
The annihilation photon can interact in the high-Z dense scintillation crystal, which in turn emits blue photons
Implementation Method 2
The blue optical photons propagate inside the crystal and are absorbed by a photodetector converting the light into an electrical signal
Implementation Method 3
the arrival time of the photons are recorded to such an extent that the annihilation location can be estimated
Data Source
AI summary
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.