Frustum-Shaped Crystal Array Module for PET Detector Photon Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In positron emission tomography (PET) detectors, the discontinuous photoelectric conversion array leads to a loss of visible light photons due to the smaller effective detection area compared to the package area, resulting in reduced detection efficiency and imaging quality.
Innovation Solution
A crystal-array module with a frustum-shaped crystal structure, where each unit crystal strip has a bevel edge for coupling with the photoelectric device, and an optional gengon-frustum combination, ensures that light is reflected and directed into the effective detection area, enhancing the number of photons entering the device, and introducing a windowing part to allow photon transfer between adjacent strips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If crystal strips are arranged with the same size as the package of photoelectric devices, then the detection area is maximized, but photons are lost due to the dead zone of the photoelectric detector
Solution Approach 1:
The patent introduces a light guide layer that extends the optical path from the crystal strip into the dead zone area of the photoelectric device. This adds a spatial dimension to photon transport, allowing photons that would normally be lost in the dead zone to be redirected and captured by the photoelectric conversion region, thus resolving the contradiction between maximizing detection area and minimizing photon loss.
Solution Approach 2:
The light guide layer acts as an intermediary between the crystal strip and the photoelectric device. It captures photons emitted in the dead zone region and redirects them toward the active photoelectric conversion area, effectively mediating the photon transport and eliminating the harmful effect of the dead zone while maintaining full crystal coverage.
2Loss of energy
If crystal strips are reduced to match the effective detection region, then photon acceptance is improved, but gaps between strips reduce detection efficiency
Solution Approach 1:
The light guide layer serves as an intermediary that bridges the gaps between adjacent crystal strips. Photons emitted at the boundaries or in the gaps can be captured and redirected by the light guide to the photoelectric conversion region, preventing photon loss in inter-stip regions while maintaining compact crystal geometry for high detection efficiency.
Solution Approach 2:
The light guide layer provides localized optical management at different positions. In regions where crystal strips are present, it enhances photon collection; in gap regions between strips, it prevents photon loss by redirecting stray photons. This local optimization resolves the contradiction between compact crystal arrangement and photon acceptance.
3Area of stationary object
If multiple photoelectric conversion devices are arranged to form a large detection area, then the detection coverage is increased, but discontinuous dead zones reduce overall performance
Solution Approach 1:
The light guide layers from multiple photoelectric conversion devices are merged to form a continuous or semi-continuous optical network across the entire detection array. This merging allows photons that would fall into dead zones between individual devices to be captured and redirected, effectively combining the optical paths and eliminating the harmful discontinuities while maintaining large detection coverage.
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 improves detection efficiency, sensitivity, and energy information precision by ensuring all photons are utilized, optimizing the detector's performance while maintaining high detection efficiency.
Implementation Method 1
A scintillation crystal is a material which can convert X-ray particles or γ-ray particles into visible light photons
Implementation Method 2
The photoelectric device is configured to receive the photons and convert the photons into an electrical signal
Implementation Method 3
each unit crystal strip has a bevel edge for coupling with the photoelectric device... ensures that light is reflected and directed into the effective detection area
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An array crystal module comprises a plurality of unit crystal strips (10). The exterior three-dimensional shape of the array crystal module is a frustum (12) or a combination of a right quadrangular prism (11) and the frustum (12), and the frustum (12) is used to be coupled with a photoelectric device (20). The frustum (12) comprises a first bottom face coupled with the photoelectric device (20) and a first top face opposed to the first bottom face, and the area of the first bottom face is smaller than that of the first top face. A fabrication method of the array crystal module includes: fabricating a crystal strip blank to obtain a unit crystal strip, performing the die cutting to obtain a unit crystal strip in the shape of a frustum or a unit crystal strip in the shape of a combination of a right quadrangular prism and a frustum according to a set obliquity and the thickness of the right quadrangular prism part, and assembling the unit crystal strips together to form an array crystal module. The above array crystal module, on the premise that the detection efficiency is guaranteed, can solve the problem of the light output loss of the crystal caused by the fact that the effective detection area of a photoelectric conversion device is smaller than a packaging area, thereby guaranteeing the sensitivity and performance of a detector.