Asymmetric Two-Half PET Scanner Geometry
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Solution Overview
Problem
Conventional PET scanner designs are costly and inflexible, with limited options for optimizing the geometry to increase the number of event counts while providing adequate sampling for reconstruction, especially for larger diameters or specific organ scanning, which affects sensitivity and patient comfort.
Innovation Solution
The introduction of a two-half PET scanner geometry, where a first detector portion is arranged circumferentially around the patient with a predetermined axial extent subtending more than 180 degrees, and a second detector portion with a smaller radius opposing the first, allowing for reduced detector material usage and increased sensitivity by optimizing the detector arrangement and type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional full-ring PET scanner geometry is used, then complete transaxial sampling is achieved, but detector cost and device complexity increase significantly
Solution Approach 1:
The detector system is divided into two separate detector portions (first and second detector portions) with different geometries. The first detector portion is arranged circumferentially around the patient with a predetermined axial extent and transaxially subtends more than 180 degrees but less than 360 degrees. The second detector portion is arranged separately and opposes the first detector portion with a smaller radius of curvature and transaxially subtends less than 180 degrees. This segmentation allows each portion to be optimized for specific imaging functions, reducing overall system complexity while maintaining sampling completeness.
Solution Approach 2:
Different detector portions are assigned different geometric configurations optimized for their specific imaging roles. The first detector portion with larger radius and greater axial extent is optimized for general transaxial sampling, while the second detector portion with smaller radius is optimized for enhanced axial sensitivity and focused imaging tasks. This local optimization allows the system to achieve complete sampling without requiring a full-ring geometry, thereby reducing detector cost and complexity.
2Device complexity
If detector material is reduced to lower cost, then detector cost decreases, but sensitivity and event count capability deteriorate
Solution Approach 1:
The system employs asymmetric detector configuration where the first detector portion has a larger radius of curvature and greater axial extent, while the second detector portion has a smaller radius of curvature. This asymmetric arrangement concentrates detector material in strategic locations where it provides maximum imaging benefit, particularly enhancing axial sensitivity without requiring proportional increases in total detector material. The asymmetric geometry allows the system to maintain high sensitivity with reduced overall detector material usage.
Solution Approach 2:
The second detector portion is positioned at a different radial distance from the patient compared to the first detector portion, creating a multi-dimensional detector arrangement. This dimensional variation allows the system to optimize sensitivity in different spatial directions - the first detector portion provides broad transaxial coverage while the second detector portion, positioned closer to the patient, enhances axial sensitivity. This multi-dimensional arrangement improves sensitivity efficiency without proportionally increasing detector material.
3Ease of operation
If a larger diameter scanner aperture is used to improve patient comfort, then patient comfort increases, but sensitivity and event count capability decrease
Solution Approach 1:
The system employs a dynamic, multi-component detector arrangement where the first and second detector portions can be independently optimized for different imaging scenarios. The flexible geometry allows the system to maintain high sensitivity in a larger aperture configuration by strategically positioning detector portions at different radial distances and axial extents, rather than requiring a fixed, compact full-ring geometry. This dynamic arrangement enables the system to accommodate larger patient comfort requirements while preserving sensitivity through optimized detector placement.
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 achieves up to 50% savings in detector cost, maintains transaxial sensitivity, and enhances axial sensitivity, enabling improved imaging performance or reduced crystal thickness, while allowing for quasi-complete sampling and better spatial resolution, particularly beneficial for focused imaging tasks like cardiac or breast imaging.
Implementation Method 1
each detector element comprises a scintillation crystal in communication with a photosensor
Implementation Method 2
each detector element comprises a scintillation crystal in communication with a photosensor
Data Source
AI summary
A positron emission tomography (PET) scanner, including a first detector portion arranged circumferentially around a patient pallet, the first detector portion having a predetermined axial extent and transaxially subtending less than 360 degrees with respect to a central axis of the scanner defined by the first detector portion, wherein the first detector portion includes a plurality of first detector elements; and a second detector portion arranged separately from and opposing the first detector section, the second detector portion including a plurality of second detector elements, the second detector elements being of a different type than the first detector elements, wherein each of the first detector elements includes photomultiplier tubes (PMTs); and each of the second detector elements includes photosensors of a different type from the PMTs of the first detector elements.