Indirect Photon-Counting X-Ray Detector With Signal Filtration
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Solution Overview
Problem
Conventional hybrid pixel array detectors (HPADs) face limitations such as small active areas due to tiling, parallax issues with higher-energy X-rays, and decreased quantum efficiency over time due to polarization, which hinder their application in analytical X-ray diffraction and other fields.
Innovation Solution
A two-dimensional indirect photon-counting X-ray detector with a thick scintillator screen and CMOS sensor, operating in non-destructive readout mode, uses real-time signal subtraction and filtration to maintain a high signal-to-noise ratio, eliminating direct interaction noise and parallax, and optimizing scintillator thickness and grain size for efficient X-ray absorption and light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick scintillator screen is used to absorb low-energy X-rays, then X-ray absorption efficiency is improved, but direct interaction between X-rays and the optical sensor increases
Solution Approach 1:
The patent introduces an intermediary layer (scintillator screen) between the X-ray source and optical sensor. This scintillator converts X-ray energy into optical photons, mediating the interaction and preventing direct X-ray contact with the sensor. The scintillator material and thickness are optimized to achieve high X-ray absorption while managing direct interaction events through statistical filtering.
Solution Approach 2:
The patent changes the parameter of scintillator thickness to optimize the balance between X-ray absorption and direct interaction suppression. By carefully selecting the thickness parameter, the system achieves sufficient absorption of low-energy X-rays while limiting the probability of direct X-ray sensor interactions to manageable levels.
2Measurement precision
If sequential frame collection is used to identify direct interaction events, then noise filtering capability is improved, but data acquisition time increases
Solution Approach 1:
The patent employs periodic action by collecting sequential frames at high speed and using statistical analysis across multiple frames to identify and filter direct interaction events. This periodic frame collection allows the system to distinguish noise from true signals through temporal patterns while maintaining efficient data acquisition.
Solution Approach 2:
The system maintains continuous data acquisition through high-speed sequential frame collection, ensuring that the useful action of X-ray detection continues uninterrupted. The filtering process operates in parallel through statistical analysis of the continuous data stream, preventing loss of acquisition time while achieving noise filtering.
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
Enables reliable photon counting of low-energy X-rays without gaps in large active areas, maintaining stable quantum efficiency and reducing noise, thus overcoming the limitations of conventional HPADs.
Implementation Method 1
a scintillator screen that absorbs an incident X-ray signal in a two-dimensional detection area and emits an optical signal in response thereto
Implementation Method 2
a two-dimensional optical sensor coupled directly to the scintillator screen that detects said optical signal emitted thereby and generates an electrical output signal
Data Source
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AI summary
An indirect, photon-counting X-ray detector capable of detecting the low-energy X-rays includes a scintillator screen that is directly coupled to a two-dimensional optical sensor. A signal filter receives an electrical output signal from the optical sensor and removes high intensity signal contributions therefrom that are indicative of direct interaction between said X-ray signal and said optical sensor. The scintillator screen has a sufficient thickness to ensure a high absorption of incident X-ray photons, and uses phosphor grains with a relatively small grain size. A cooling apparatus in thermal communication with the optical sensor may be used to control its temperature. The signal filter maintains a running average of changes in measured pixel output values for consecutive measurements, and replaces a measured value caused by a direct interaction event with a value equal to a previous measured value plus said running average.