X-Ray Detection Structure Using Wavelength-Shifting Fibers
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Solution Overview
Problem
Existing backscatter x-ray imaging systems using scanning pencil beams face challenges in achieving high-resolution transmission images due to the limitations of monolithic scintillating detectors, which are either expensive or result in low-resolution images when using wide scanning beams.
Innovation Solution
A dual-energy transmission detector design incorporating wavelength-shifting fibers (WSFs) optically coupled to scintillator volumes, with a signal combiner and photodetectors to enhance spatial resolution by selectively combining signals from multiple ribbons, allowing for higher imaging resolution even with wide scanning beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large monolithic scintillating medium is used to intercept the scanning beam, then transmission images can be created, but the system becomes expensive and less compact
Solution Approach 1:
The patent divides the monolithic scintillating medium into multiple scintillator blocks arranged in an array. Each block is read out by wavelength-shifting fibers, creating a segmented detector structure that reduces complexity and cost while maintaining imaging resolution capability
Solution Approach 2:
The patent introduces wavelength-shifting fibers that extend along the scan direction, adding a dimensional element that allows signal collection from multiple scintillator blocks. This fiber-based readout approach transforms the detector architecture from a simple monolithic structure to a multi-dimensional array with improved resolution capabilities
2Volume of moving object
If wavelength-shifting fibers are used to read out scintillation light, then a compact low-profile design is achieved, but manufacturing cost increases
Solution Approach 1:
The detector uses multiple smaller scintillator blocks instead of one large monolithic crystal, allowing the use of shorter wavelength-shifting fibers. This segmentation reduces the total fiber length required and lowers manufacturing costs while maintaining the compact form factor
Solution Approach 2:
The patent optimizes the dimensions and arrangement of scintillator blocks to minimize the required fiber length and improve manufacturing efficiency. By adjusting geometric parameters of the detector components, the system achieves compactness without proportionally increasing manufacturing complexity
3Ease of manufacture
If a single large scintillator is used, then the detector is less expensive, but imaging resolution decreases
Solution Approach 1:
The patent employs an array of smaller scintillator blocks rather than a single large crystal. Each block can be manufactured more easily and at lower cost, while the collective array provides the spatial resolution needed for high-quality imaging
Solution Approach 2:
Wavelength-shifting fibers act as intermediaries between the segmented scintillator blocks and the photodetector array. These fibers collect and transport light signals from multiple small blocks, enabling them to function collectively as a high-resolution detector while keeping individual component costs low
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 detector system achieves higher imaging resolution compared to equivalent systems using prior art x-ray detector systems, enabling effective transmission imaging with enhanced spatial resolution and cost-effectiveness.
Implementation Method 1
one or more scintillator volumes configured to receive x-rays from the scanning beam transmitted through a target, as well as to produce scintillation photons responsive to receiving the x-rays
Implementation Method 2
a plurality of ribbons of wavelength-shifting fibers optically coupled to one or more scintillator volumes, wherein the ribbons are arranged to couple to the scintillator volume in a repeating pattern
Data Source
AI summary
A system for detecting a scanning beam of x-rays includes one or more scintillator volumes oriented along an x-ray scan axis. The scintillator volume(s) receive x-rays transmitted through a target and produce scintillation photons responsively. Two or more ribbons of wavelength-shifting fibers (WSFs) are optically coupled to the scintillator volume(s) along the axis via a spatial periodic adjacency of the ribbons to the axis. The ribbons receive scintillation photons from the scintillator volume(s) via the spatial periodic adjacency as the x-ray beam scans over the scan axis. At least one respective photodetector coupled to an end of each respective ribbon detects the scintillation photons carried by the respective ribbon produces a respective signal. A signal combiner selectively combines signals from one or more ribbons, for beam positions along the scan axis, to create a combined signal representing a scan of the target. The scan can have enhanced spatial resolution.