X-ray Detector Collimator Threshold Plate Thickness
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Solution Overview
Problem
In X-ray CT apparatuses, the integration of the X-ray detector and data acquisition system (DAS) leads to the DAS being exposed to unabsorbed X-rays, causing potential breakdowns and preventing tiling arrangements of detection elements.
Innovation Solution
The X-ray CT apparatus incorporates a collimator with a threshold plate and light reflectors between scintillators, ensuring that the DAS is not exposed to unabsorbed X-rays by setting the threshold plate thickness greater than or equal to the gap thickness between scintillators, thereby blocking scattered radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the X-ray detector and DAS are integrally formed, then the detection element and DAS can be arranged in a tiling fashion improving manufacturing efficiency, but the DAS becomes exposed to unabsorbed X-rays causing potential breakdowns
Solution Approach 1:
A collimator is introduced as an intermediary component between the X-ray detector and the DAS. The collimator absorbs unabsorbed X-rays that would otherwise reach the DAS, acting as a mediator that protects the DAS from radiation while allowing the integral formation of the detector and DAS modules.
Solution Approach 2:
The harmful function of unabsorbed X-rays is extracted and isolated by the collimator, which captures and absorbs these radiation before they can reach the DAS. This separation protects the DAS from the harmful effects while maintaining the integrated structure.
2Reliability
If the DAS is arranged at a position not exposed to X-rays in an integral structure, then DAS reliability is improved, but the detection element and DAS cannot be arranged in a tiling fashion reducing manufacturing efficiency
Solution Approach 1:
The collimator serves as a mediator that enables the DAS to be positioned in an integrated configuration while still protecting it from X-ray exposure. This intermediary allows both tiling arrangement for manufacturing efficiency and reliable DAS positioning.
3Reliability
If the threshold plate thickness is increased to block scattered radiation, then DAS protection from X-rays is improved, but the overall detector size and complexity increase
Solution Approach 1:
The collimator is positioned specifically at the boundary between the detection elements and the DAS, providing localized protection only where needed. This targeted approach protects the DAS from scattered radiation without requiring the entire detector structure to be more complex or larger.
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 configuration prevents X-ray leakage to the DAS, even when the X-ray detector and DAS are integrally formed, thus avoiding potential breakdowns and allowing for tiling arrangements of detection elements.
Implementation Method 1
The scintillator absorbs X-rays collimated at a preceding stage to thereby produce light (fluorescence)
Implementation Method 2
The PD converts the light into an electric signal by the optical sensor
Implementation Method 3
a collimator having a threshold plate with a thickness Wc to eliminate scattered radiation from the X-ray
Data Source
AI summary
An X-ray detector of an X-ray CT apparatus has a collimator, a plurality of scintillators, a light reflector and a plurality of photodiodes. The collimator has a threshold plate with a thickness Wc to eliminate scattered radiation from an X-ray. The plurality of scintillators emit light based on the X-ray. The light reflector is provided in a gap between adjacent scintillators of the plurality of scintillators. The plurality of photodiodes convert the light of each of the plurality of scintillators into the electric signal. The thickness Wc of the threshold plate mounted on the X-ray incident side of the adjacent scintillators, and a thickness Ws of the gap has a relationship shown in a following expression: Wc≧Ws.