Direct Conversion X-Ray Detector Using Composite Electrodes
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Solution Overview
Problem
Current x-ray detection methods, both indirect and direct, face inefficiencies such as poor absorption efficiency in gas-filled ion-chambers, high costs and quality issues with compound semiconductors like CZT, and limitations in measuring both attenuation and energy of x-rays without wasting signals or increasing patient dose.
Innovation Solution
A direct conversion x-ray detector design utilizing electrodes of varying thicknesses and dielectric materials between them, where x-ray absorption occurs primarily in the electrodes, enabling nearly 100% absorption and energy-sensitive signals without the need for scintillator materials or complex filtration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If gas-filled ion-chambers are used for direct conversion, then the afterglow effect is reduced, but the x-ray absorption efficiency becomes poor
Solution Approach 1:
The patent uses composite structures combining high-Z electrode materials (for x-ray absorption) with dielectric materials (for signal generation). This composite approach allows the system to achieve both high absorption efficiency and fast signal decay characteristics that neither material alone could provide.
Solution Approach 2:
The patent changes the physical state from gas-filled chambers to solid-state structures with varying dielectric thicknesses. By adjusting the thickness parameter of the dielectric layer and the composition of electrodes, the system optimizes both absorption efficiency and signal characteristics simultaneously.
2Use of energy by moving object
If scintillator material is used for indirect detection, then the x-ray to light conversion is achieved, but the afterglow effect persists for tens of milliseconds
Solution Approach 1:
The patent extracts and eliminates the scintillator material from the detection system, using direct conversion through dielectric materials and electrodes. This removes the source of the afterglow effect while maintaining energy conversion capability through radiation-induced conductivity.
3Quantity of substance
If compound semiconductors like CZT are used for direct conversion, then the x-ray absorption efficiency is improved, but the cost and quality issues arise
Solution Approach 1:
The patent replaces expensive compound semiconductor materials with more readily manufacturable dielectric materials and standard electrodes. While the individual components are simpler, their combination achieves comparable absorption efficiency at lower cost and with better manufacturing scalability.
Solution Approach 2:
The patent changes the material composition parameters from rare compound semiconductors to common dielectric materials with optimized thickness parameters. This parameter optimization allows achieving high absorption efficiency using materials that are easier and cheaper to manufacture.
4Measurement precision
If stacked detectors are used for energy discrimination, then the energy sensitivity is improved, but the signal loss occurs due to absorption in intermediate materials
Solution Approach 1:
The patent transitions from a vertical stacking architecture to a lateral multi-layer architecture where detectors are arranged side-by-side rather than stacked vertically. This dimensional change eliminates the need for intermediate absorbing materials between layers, reducing signal loss while maintaining energy discrimination capability through differential absorption paths.
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 design achieves high x-ray absorption efficiency and energy sensitivity, reducing signal loss and afterglow effects, while allowing for detection across a range of energies without the need for costly materials or increased patient exposure.
Implementation Method 1
utilizing the radiation induced conductivity ("RIC") effect in solid insulating materials
Implementation Method 2
the incoming photons ionize the material of which the detector is made, releasing energetic electrons through interactions such as the photoelectric effect
Data Source
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AI summary
An x-ray detector capable of directly converting x-ray radiation into electrical signals utilizes the radiation induced conductivity of various solid, electrically insulating materials. The detector is configured comprising one or more anodes and cathodes separated by various thicknesses of dielectric material wherein ionization occurs primarily in the electrodes of such detector structure. The radiation induced conductivity of the dielectric material can be modulated by controlling the size, orientation and composition of the electrodes and the dielectric materials as well as the electrical bias between anode and cathode.