Photon Counting Detector Layout for Wide Flux Dynamic Range
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Solution Overview
Problem
Photon counting detectors face inaccuracies due to wide dynamic ranges of photon flux rates, leading to issues like deadtime losses, pulse pileup, and statistical errors, especially when scanning large subjects with varying tissue thicknesses.
Innovation Solution
Implementing a radiographic scanning system with a photon source that emits beams at alternating flux rates and a detector with alternating pixel sizes and configurations, including slit apertures and photon absorbers to manage photon flux effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single uniform pixel size is used in the photon counting detector, then the detector structure is simple, but measurement precision deteriorates due to inability to handle wide dynamic ranges of photon flux rates
Solution Approach 1:
The detector is divided into multiple pixel types with different sizes (first pixels with first size, second pixels with second size) to handle different photon flux rates. This segmentation allows each pixel type to be optimized for specific flux conditions, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
Different regions of the detector are assigned different pixel sizes based on the expected photon flux in each region. Areas with higher photon flux use smaller pixels to avoid saturation, while areas with lower flux use larger pixels to improve statistical accuracy, thereby achieving local optimization of measurement precision.
2Productivity
If the photon source emits at high flux rates, then productivity is improved, but measurement precision deteriorates due to deadtime losses and pulse pileup
Solution Approach 1:
The system dynamically switches between different pixel types based on the detected photon flux rate. When high flux rates are detected, the system activates smaller pixels that can handle high count rates without saturation, while maintaining the ability to switch to larger pixels for lower flux conditions, thus maintaining measurement precision across varying productivity levels.
Solution Approach 2:
The detector operates in periodic cycles, alternating between different pixel types based on the photon flux conditions. This periodic switching allows the system to maintain optimal measurement precision across a wide range of flux rates while sustaining high productivity.
3Measurement precision
If the pixel density is uniform across the detector, then manufacturing is easier, but measurement precision deteriorates when scanning large subjects with varying tissue thicknesses
Solution Approach 1:
The detector implements non-uniform pixel density where central regions have different pixel densities compared to outer regions. This local quality variation allows the detector to handle varying tissue thicknesses in different body regions, improving measurement precision while accepting increased manufacturing complexity.
Solution Approach 2:
The detector is segmented into regions with different pixel density characteristics to match the varying attenuation properties of different body parts. This segmentation enables optimized photon counting for each region while requiring more complex manufacturing processes.
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
The system enhances accuracy and reproducibility by accurately recording photon counts across varying flux rates, reducing errors and maintaining image quality in both thin and thick target regions.
Implementation Method 1
a photon absorber positioned adjacent an outer portion of the slit aperture to absorb a portion of the photons emitted from the photon source
Implementation Method 2
The radiation detector elements receiving the transmitted radiation produce electrical signals
Data Source
AI summary
Systems and methods for improving radiographic scanning. In an example, the technology relates to a system for performing radiographic scanning. The system includes a photon source configured to emit photons. The system also includes a photon counting detector for detecting photons emitted from the photon source after passing through a target. The photon counting detector comprising first pixels having a first size and second pixels having a second size, and the first size is greater than the second size.