Photon Counting CT Detector Electric Field Optimization
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Solution Overview
Problem
Photon counting X-ray computed tomography (CT) imaging systems suffer from poor count rate stability due to insufficient electric fields in semiconductor detectors, despite having sufficient thickness and applied voltage within safety limits.
Innovation Solution
An X-ray radiation detector with a semiconductor material plate thickness of at least 1.9 mm and an applied bias voltage of 1050 VDC to 1500 VDC, generating an electric field of at least 550 VDC/mm, is used to enhance count rate stability in photon counting CT imaging systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor detector thickness is increased to improve X-ray absorption, then the absorption efficiency is improved, but the count rate stability deteriorates due to insufficient electric field strength
Solution Approach 1:
The patent applies parameter changes by increasing the applied bias voltage from conventional levels to 1050-1500 VDC, which directly increases the electric field strength to at least 550 VDC/mm. This parameter change resolves the contradiction by providing sufficient electric field strength in thick detectors (at least 1.9 mm) to maintain count rate stability while preserving X-ray absorption efficiency.
2Reliability
If the applied bias voltage is increased to improve count rate stability, then the count rate stability is improved, but the safety compliance deteriorates due to approaching maximum voltage limits
Solution Approach 1:
The patent applies partial or excessive action by implementing a specific voltage range (1050-1500 VDC) that provides sufficient electric field strength for count rate stability while remaining within safety compliance limits. This approach achieves the necessary performance improvement without exceeding maximum safe voltage levels, balancing effectiveness with safety.
3Object-affected harmful factors
If the semiconductor detector thickness is increased to reduce X-ray radiation dose, then the radiation dose to patient is reduced, but the diagnostic efficacy deteriorates due to poor count rate stability
Solution Approach 1:
The patent applies parameter changes by optimizing both detector thickness (at least 1.9 mm) and applied bias voltage (1050-1500 VDC) to achieve sufficient electric field strength (at least 550 VDC/mm). This combination allows thick detectors that reduce patient radiation dose while maintaining count rate stability through the enhanced electric field, thereby preserving diagnostic efficacy.
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 improves count rate stability, reduces the number of non-conforming pixels, and achieves higher diagnostic efficacy with reduced X-ray radiation dose, while maintaining compliance with safety standards.
Implementation Method 1
the charge cloud resulting from an X-ray photon impinging on a sensor
Implementation Method 2
an electric field of at least 550 VDC/mm is generated in the semiconductor material plate
Data Source
AI summary
An X-ray radiation detector includes a semiconductor material plate, at least one cathode located on a first side of the semiconductor material plate, and at least one anode located on a second side of the semiconductor material plate. The semiconductor material plate thickness is at least 1.9 mm. The X-ray radiation detector is configured to operate at an absolute value of applied bias voltage of 1050 VDC to 1500 VDC, such that an electric field of at least 550 VDC/mm is generated in the semiconductor material plate.