Pinhole Collimator Virtual Sub-Pixel Segmentation
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Solution Overview
Problem
Conventional Nuclear Medicine (NM) imaging systems with multiple detectors face limitations in sensitivity due to the size of detector heads and the arrangement of Cadmium Zinc Telluride (CZT) wafers, which restricts the usable area and image quality.
Innovation Solution
The use of a pinhole collimator with an array of pinhole openings that correspond to single physical pixels, allowing radiation to be confined within a single pixel and improving image quality by dividing physical pixels into virtual sub-pixels, reducing statistical noise, and allowing for a shorter collimator height, enabling more detector heads to be placed around the object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional detector arrangements with thicker detectors or stacked identical layers are used, then sensitivity may be improved, but device complexity and detector head size increase, limiting the usable area and number of detector heads that can be placed around the subject
Solution Approach 1:
The patent divides each physical pixel into multiple virtual sub-pixels (e.g., 3x3=9 sub-pixels per pixel) through software processing. This segmentation allows the system to achieve improved sensitivity and reduced noise without physically increasing detector head size or stacking multiple detector layers, thereby resolving the contradiction between sensitivity and device complexity
Solution Approach 2:
The patent transitions from a two-dimensional physical pixel arrangement to a three-dimensional virtual sub-pixel space by introducing the depth dimension through multiple absorption depth assignments. This allows enhanced sensitivity through virtual stacking in the depth dimension without adding physical detector layers, thus improving sensitivity while maintaining compact detector head design
2Reliability
If more detector heads are placed around the subject to improve sensitivity, then the proportion of radiation received increases, but the detector head size and arrangement constraints limit the number of detectors that can be positioned
Solution Approach 1:
By segmenting physical pixels into virtual sub-pixels, the system effectively increases the detector area without physically expanding the detector head. This allows more virtual detection elements to be positioned around the subject, improving sensitivity while maintaining the same physical footprint and usable area for detector placement
3Measurement precision
If physical pixels are divided into virtual sub-pixels, then statistical noise is reduced and image quality improves, but processing complexity increases
Solution Approach 1:
The patent implements pixel segmentation into virtual sub-pixels with associated absorption depth assignments. While this does increase processing requirements, the structured approach (dividing pixels into regular grids of sub-pixels) and the use of lookup tables for absorption depth corrections help manage the processing complexity while achieving improved image quality and reduced statistical noise
4Device complexity
If collimator height is reduced to enable more compact detector head design, then device complexity decreases and more detector heads can be placed, but sensitivity may be compromised
Solution Approach 1:
The patent compensates for the reduced collimator height by introducing virtual depth information through multiple absorption depth assignments for each physical pixel. This creates an effective third dimension in the detection space, allowing the system to maintain sensitivity despite the physically shorter collimator, thus resolving the contradiction between compact design and sensitivity
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 enhances sensitivity, spatial resolution, and image quality by reducing radiation penetration to non-associated pixels and minimizing statistical noise, while allowing for a more compact detector head design.
Implementation Method 1
an array of pinhole openings are used in a collimator for a detector system. A pinhole collimator includes an array of pinholes that defines multiples cells. Each cell includes or corresponds to only a single physical pixel of the detector and only a single pinhole of the array.
Implementation Method 2
The semiconductor detector 110 produces signals in response to absorption events (e.g., photons produced in response to a radiopharmaceutical that has been administered to an object being imaged that impact the semiconductor detector 110).
Data Source
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AI summary
A detector assembly 100 is provided that includes a semiconductor detector 110, a pinhole collimator 130, and a processing unit 150. The semiconductor detector 110 has a first surface 112 and a second surface 114 opposed to each other. The first surface includes pixels, and the second surface includes a cathode electrode. The pinhole collimator 130 includes an array of pinhole openings corresponding to the pixels. Each pinhole opening is associated with a single pixel of the semiconductor detector, and the area of each pinhole opening is smaller than a corresponding area of the corresponding pixel. The processing unit 150 is operably coupled to the semiconductor detector 110 and configured to identify detected events within virtual sub-pixels distributed along a length and width of the semiconductor detector 110. Each pixel includes a plurality of corresponding virtual sub-pixels (as interpreted by the processing unit), wherein absorbed photons are counted as events in a corresponding virtual sub-pixel.