Imaging Detector Residual Charge Circuit for Spatial Accuracy
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Solution Overview
Problem
Current CT scanner systems face limitations in spatial accuracy during low signal, low-dose imaging procedures due to the use of current-to-frequency converters, which result in data skewing and increased circuitry area, cost, and power requirements.
Innovation Solution
Incorporating a residual charge collection circuit electrically coupled to the current-to-frequency converter to store charge from the end of one integration period to the start of the next, allowing for accurate measurement of total charge without increasing circuit complexity or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a current-to-frequency converter is used as the A/D converter, then the circuit implementation is simple, but the spatial accuracy is limited in low signal, low-dose imaging procedures
Solution Approach 1:
The patent applies preliminary action by capturing and storing the residual charge at the end of each integration period before it is lost. The residual charge storage circuit holds this charge until it can be properly processed and added to the next integration period's charge, preventing data loss and maintaining spatial accuracy without requiring a completely different converter architecture
Solution Approach 2:
The patent introduces an intermediary residual charge storage circuit that acts as a buffer between the current-to-frequency converter and the data processing system. This intermediary component captures the residual charge that would otherwise be lost and facilitates its proper incorporation into the measurement data, resolving the conflict between simple circuit implementation and measurement precision
2Reliability
If data re-alignment is performed to compensate for charge overlap, then signal to noise is improved, but spatial accuracy is reduced due to skewing
Solution Approach 1:
The patent applies preliminary action by proactively capturing the residual charge at the end of each integration period and storing it in a dedicated storage circuit. This preliminary capture prevents the charge overlap problem from occurring in the first place, eliminating the need for subsequent data re-alignment operations that would cause spatial skewing while still maintaining signal quality
3Measurement precision
If approaches are taken to overcome spatial skewing, then spatial accuracy is improved, but circuitry area, cost and power requirements increase
Solution Approach 1:
The patent applies the taking out principle by extracting and isolating the residual charge from the main integration process into a separate storage circuit. This extraction allows the residual charge to be handled independently and properly incorporated into the measurement data without requiring complex circuitry to prevent or correct spatial skewing, thus improving spatial accuracy without significantly increasing circuitry area, cost, or power requirements
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 approach enhances spatial accuracy by eliminating data skewing and reducing the need for additional circuitry, while maintaining efficient data collection and processing, even with fast x-ray tube operations.
Implementation Method 1
A CT scanner includes an x-ray tube mounted on a rotatable gantry that rotates around an examination region about a longitudinal or z-axis. A detector array subtends an angular arc opposite the examination region from the x-ray tube. The detector array detects radiation that traverses the examination region and a subject or object therein and generates a signal indicative thereof.
Implementation Method 2
The scintillator array generates light indicative of radiation impinging thereon, the photosensor array generates an electrical signal indicative of the light
Implementation Method 3
the photosensor array generates an electrical signal indicative of the light
Data Source
AI summary
A detector array (112) of an imaging system (100) includes a radiation sensitive detector (202/204/206) configured to detect radiation and generates a signal indicative thereof and electronics (208) in electrical communication with the radiation sensitive detector. The electronics include a current-to-frequency converter (300) configured to convert the signal into a pulse train having a frequency indicative of a charge collected during an integration period. The electronics further include a residual charge collection circuit (322) electrically coupled to current-to-frequency converter. The residual charge collection circuit is configured to store charge collected by the integrator for an end portion of the integration period that does not results in a pulse of the pulse train, utilizing much of the electronics already in the current-to-frequency converter electronics.