X-ray CT Offset Correction via Readout Switch Control
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Solution Overview
Problem
Long-duration X-ray computed tomography scans face challenges in accurately correcting the drift component of output values due to large fluctuations, which existing techniques struggle to address effectively.
Innovation Solution
The X-ray computed tomography apparatus acquires offset data during scanning by turning readout switches to the OFF state, allowing for the collection of offset data instead of projection data, and uses interpolation to handle missing data, thereby enabling accurate offset correction even during long scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset data is acquired before the start of scan or after the end of scan, then offset correction can be performed, but drift component generated during long scan cannot be accurately corrected due to large fluctuation
Solution Approach 1:
The system performs preliminary offset data acquisition at multiple predetermined timings (before scan, during scan at intermediate points, after scan) to establish baseline offset values. These preliminary measurements enable correction of drift components that develop during long-duration scans, as each preliminary offset data set corresponds to a specific time point and can be used to correct projection data acquired at that same time point.
Solution Approach 2:
The system continuously monitors offset components at multiple time points during the scan process and uses this feedback to dynamically correct drift fluctuations. By comparing offset data acquired at different timings, the system can detect and compensate for drift components that develop during the scan, maintaining correction accuracy throughout the entire scan duration.
2Quantity of substance
If offset data is acquired during scan by turning readout switch OFF, then sufficient offset data can be acquired for correction, but projection data is missed at that timing
Solution Approach 1:
The system acquires offset data for only a predetermined number of lines (partial action) rather than all lines during the scan. This selective acquisition obtains sufficient offset data for correction while minimizing the amount of missed projection data. The predetermined number is optimized to provide adequate offset measurements without excessive data loss.
Solution Approach 2:
The readout switch acts as an intermediary mechanism that can be switched between ON and OFF states. When OFF, it prevents projection data from being read out but allows offset data to be acquired instead. This intermediary function enables the system to alternately acquire offset data and projection data, balancing the needs for both types of information.
3Productivity
If scan is performed for long time, then more projection data can be acquired, but drift component fluctuation increases making correction difficult
Solution Approach 1:
The long scan duration is segmented into multiple time intervals, with offset data acquisition scheduled at predetermined timings within each interval (before scan, during scan, after scan). This segmentation allows the system to capture offset components at different stages of the scan, enabling accurate correction of drift fluctuations that develop over the entire long-duration scan while maintaining high productivity.
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 ensures accurate offset correction during long scans, improving image quality by allowing sufficient offset data acquisition and interpolation of missing projection data, thus addressing the challenge of drift fluctuations.
Implementation Method 1
an X-ray detection element, which outputs an electric signal according to a detected X-ray
Implementation Method 2
an A/D convertor, which A/D-converts the electric signal
Implementation Method 3
a readout switch, which switches a connection between the X-ray detection element and the A/D convertor
Data Source
AI summary
According to one embodiment, an X-ray computed tomography apparatus includes an X-ray detection element, an A/D convertor, a readout switch, and readout control circuitry. The X-ray detection element outputs an electric signal corresponding to a detected X-ray. The A/D convertor A/D-converts the electric signal. The readout switch switches a connection between the X-ray detection element and the A/D convertor. The readout control circuitry acquires, as offset data, data which is output by the A/D convertor in a state where the readout switch is OFF instead of projection data which is output by the A/D convertor according to the electric signal in a state where the readout switch is ON, in a view during a scan.