Edge-On Semiconductor Crystal Imager for High Resolution PET
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Solution Overview
Problem
Conventional PET devices face challenges in achieving high spatial resolution and detection sensitivity due to the complexity and cost of manufacturing finely pixellated scintillation crystal arrays, with scintillation crystal sheet detectors suffering from low efficiency in stopping high-energy photons and requiring precise alignment of minute crystal elements with photodetector elements.
Innovation Solution
The use of semiconductor crystal detectors arranged edge-on with respect to incoming photons, such as Cadmium-Zinc-Telluride (CZT) crystals, which directly absorb photons to produce electric pulses for position determination, allowing for superior photon detection efficiency and energy resolution without the need for scintillation crystals, and employing a cross-strip or pixellated electrode configuration for 3-D event localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scintillation crystal arrays are made finely pixellated to achieve high spatial resolution, then measurement precision improves, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent extracts and eliminates the scintillation crystal component from the detection system, replacing it with direct semiconductor photon detection. This removes the need for finely pixellated crystal arrays and their associated manufacturing complexities while maintaining high spatial resolution through direct electronic detection methods
Solution Approach 2:
The patent replaces the mechanical/optical system of scintillation crystals converting photons to light and then to electrical signals with a direct semiconductor electronic detection system. This substitution eliminates the need for precise mechanical alignment of crystal elements with photodetectors while achieving comparable or superior measurement precision
2Measurement precision
If scintillation crystal sheets are made thin to reduce beam spread for better resolution, then measurement precision improves, but detection efficiency decreases due to low photon stopping power
Solution Approach 1:
The patent changes the fundamental detection parameter from optical signal generation (scintillation) to direct electrical signal generation (semiconductor detection). This parameter change enables thin detector designs to maintain high detection efficiency because semiconductor materials have superior photon absorption coefficients compared to scintillation materials, eliminating the trade-off between thickness and detection efficiency
3Reliability
If crystal sheet thickness is increased to improve photon stopping efficiency, then detection efficiency improves, but spatial resolution deteriorates due to increased beam spread
Solution Approach 1:
The patent replaces the mechanical constraint of crystal thickness with an electronic solution in semiconductor detectors. The direct electronic detection mechanism allows for thin detector designs that maintain high detection efficiency without the beam spread issues that plague scintillation crystal systems, as electronic signals do not undergo optical scattering
4Reliability
If conventional scintillation crystal systems are used, then detection capability is achieved, but manufacturing cost and complexity increase due to precise alignment requirements
Solution Approach 1:
The patent extracts and removes the scintillation crystal component entirely, replacing it with a monolithic semiconductor detector structure. This elimination of the two-component system (crystal + photodetector) and their precise alignment requirements dramatically simplifies manufacturing while maintaining full detection capability
Solution Approach 2:
The patent merges the photon absorption and electrical signal generation functions into a single semiconductor detector component. This consolidation eliminates the need for separate scintillation crystals and photodetectors, removing alignment requirements and simplifying the manufacturing process while preserving detection functionality
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 approach significantly increases image counts, reduces random and scatter coincidence background, and enhances image data quantification and contrast resolution, while being cost-effective and simpler to manufacture than traditional scintillation crystal systems, with improved spatial and energy resolutions leading to a log order increase in molecular probe sensitivity.
Implementation Method 1
semiconductor crystal detectors arranged in an edge-on orientation with respect to emitted photons from a subject to directly detect the emitted photons
Implementation Method 2
which directly absorb photons to produce electric pulses for position determination
Data Source
AI summary
A radiation imaging device (10). The radiation image device (10) comprises a subject radiation station (12) producing photon emissions (14), and at least one semiconductor crystal detector (16) arranged in an edge-on orientation with respect to the emitted photons (14) to directly receive the emitted photons (14) and produce a signal. The semiconductor crystal detector (16) comprises at least one anode and at least one cathode that produces the signal in response to the emitted photons (14).