X-ray detector sensitive volume control for pile-up reduction
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Solution Overview
Problem
X-ray devices face challenges with the pile-up effect, where multiple photons detected within a short time interval are registered as a single event with incorrect energy, leading to lost counts and distorted energy spectra, particularly in regions with high photon flux or weak attenuation, such as lung tissue, and existing solutions like dynamic beam-shaping filters are complex and costly.
Innovation Solution
An x-ray device with adjustable detector elements that control their sensitive volume based on the geometric structure of the object being imaged, reducing the sensitive volume in areas exposed to high photon flux and maintaining it in areas with lower flux to minimize pile-up and optimize energy resolution, without the need for complex dynamic filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intensity of the x-ray beam is reduced to avoid pile-up, then the pile-up effect is reduced, but the signal-to-noise ratio deteriorates and image quality decreases
Solution Approach 1:
The patent applies local quality by making different regions of the detector have different sensitive volumes. Detector elements receiving high photon flux (direct beam or weakly attenuated regions) have reduced sensitive volumes to minimize pile-up, while elements receiving lower flux maintain full sensitive volume for optimal signal detection. This spatially varying sensitive volume configuration allows the system to maintain high signal-to-noise ratio in low-flux regions while preventing pile-up in high-flux regions.
2Reliability
If dynamic beam-shaping filters are used to reduce pile-up in high-flux regions, then the pile-up effect is reduced, but the device complexity and cost increase significantly
Solution Approach 1:
The patent replaces the mechanical dynamic beam-shaping filter system with an electronic control system that adjusts the sensitive volume of detector elements. Instead of physically moving filters or changing beam shape mechanically, the system electronically modulates the detection sensitivity of individual detector elements based on their received photon flux. This substitution eliminates complex mechanical components while achieving the same pile-up reduction effect.
3Reliability
If the sensitive volume of detector elements is reduced to minimize pile-up, then the pile-up effect is reduced, but the detection efficiency and energy resolution deteriorate
Solution Approach 1:
The patent applies dynamics by making the sensitive volume of detector elements adjustable rather than fixed. The sensitive volume is dynamically modified based on the photon flux conditions: reduced in high-flux regions to prevent pile-up, and maintained at full size in low-flux regions to preserve detection efficiency and energy resolution. This dynamic adaptation allows the detector to optimize performance for different local conditions without compromising overall measurement precision.
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 effectively reduces the pile-up effect and improves energy resolution by adapting the detector sensitivity to the object's geometry, allowing for accurate imaging without the complexity and cost of dynamic filters, even in regions with varying attenuation coefficients.
Implementation Method 1
an x-ray photon entering the sensitive volume produces an electric signal used for generating the image data
Implementation Method 2
when two or more photons arrive at the radiation detector within a time interval that is shorter than the so-called deadtime of the detector, they are registered as a single event with a very high (wrong) energy
Data Source
AI summary
The invention relates to an x-ray device (1) for imaging an object (41). A radiation detector (3) of the x-ray device includes detector elements (21) for detecting radiation, each detector element (21) comprising an adjustable sensitive volume, where an x-ray photon entering the sensitive volume produces an electric signal used for generating the image data. Further, the device comprises a control unit (9) configured to control the sensitive volume of at least one of the detector elements (21) in accordance with a geometric structure of the object (41) to be imaged in order to reduce a pile-up effect in the detector element. Moreover, the invention relates to a method for operating the device (1) and to a computer program for carrying out the method.