X-ray Detector with Solid-State Photomultiplier for Scatter Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional X-ray imaging systems face challenges in detecting contraband materials due to inadequate penetration depth and high scatter radiation, leading to poor image quality and inability to distinguish between benign and threat materials, especially in high-density cargo.
Innovation Solution
An advanced X-ray inspection system with a high dynamic range detector configuration, including multiple photodiodes of varying areas and a solid-state photomultiplier, coupled with energy-sensitive single-photon counting electronics and a processing unit that rejects scatter radiation below a threshold energy, enhancing penetration and image contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If higher intensity X-ray sources are used to enhance penetration, then penetration depth is improved, but scatter radiation increases causing image quality degradation
Solution Approach 1:
The patent utilizes Compton scattering physics to enable energy-sensitive detection. By measuring the energy of scattered photons, the system can distinguish between primary (useful) and scattered (harmful) radiation, converting the harmful scatter into a detectable signal that provides material composition information while enabling scatter rejection through energy thresholding.
Solution Approach 2:
The system changes the parameter of detection from simple intensity measurement to energy-resolved detection. By incorporating solid-state photomultipliers and single-photon counting electronics, the detector can resolve photon energy, allowing the system to filter scattered radiation based on its characteristic energy loss while maintaining sensitivity to primary high-energy photons for deep penetration imaging.
2Reliability
If conventional ADCs with 16-20 bits resolution are used, then electronic noise is reduced, but dynamic range is insufficient to detect both low and high intensity X-ray signals
Solution Approach 1:
The patent replaces conventional analog-to-digital conversion with a single-photon counting approach using solid-state photomultipliers. This substitution enables the system to achieve effectively 24-bit or higher dynamic range by counting individual photons and their energies, bypassing the noise limitations of high-resolution ADCs while maintaining compatibility with pulsed X-ray sources through time-gated detection.
3Object-affected harmful factors
If collimators are used to reduce scatter, then scatter radiation is reduced, but the collimators themselves produce scatter and device complexity increases
Solution Approach 1:
The patent extracts the scatter rejection function from the mechanical collimator and relocates it to the electronic detection stage. By using energy-sensitive single-photon counting, the system electronically filters scattered photons based on their reduced energy, eliminating the need for complex collimator structures that generate their own scatter while achieving superior scatter rejection.
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 effectively scans high-density cargo with improved penetration depth and reduced scatter radiation, achieving higher image contrast and resolution, enabling better detection of both low and high-intensity signals, thus enhancing the overall quality of radiographic images.
Implementation Method 1
the detectors comprise scintillating crystals that convert the X-rays to light rays
Implementation Method 2
coupled to silicon photodiodes that convert such light rays to a measureable electronic signal
Implementation Method 3
Scattered radiation is a type of unwanted signal or 'noise' in the image and tends to blur and obscure the image
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A
AI summary
The present specification provides an X-ray inspection system including an X-ray source and a corresponding detector for detecting transmitted X rays having a wide range of intensities. The detector includes at least one crystal for producing a light signal upon interaction with X-rays. Each crystal is connected to at least one photodiode and a photomultiplier. A processing unit connected with the crystal rejects all detected radiation having energies below a predefined threshold value.