X-ray CT Table Deflection Correction via Prescan
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Solution Overview
Problem
Conventional X-ray CT apparatuses fail to accurately correct for both displacement and inclination of the table during imaging, leading to potential misdiagnosis due to reliance on software correction methods that do not account for table inclination.
Innovation Solution
The X-ray CT apparatus includes a processing circuitry that performs a prescan to calculate and correct for both vertical displacement and inclination of the table, using a combination of table driving and tilt driving circuits to adjust the table and gantry position, ensuring accurate image acquisition by hardware correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If software correction is used to smooth displacement, then displacement correction is achieved, but inclination correction is not performed leading to potential misdiagnosis
Solution Approach 1:
The patent replaces software-based image correction with a hardware-based mechanical correction system. The table driving circuit and tilt driving circuit physically adjust the table position and gantry angle to compensate for deflection, rather than attempting to correct the image data after acquisition. This mechanical substitution ensures both displacement and inclination are corrected at the source, preventing misdiagnosis while maintaining image accuracy.
Solution Approach 2:
The system performs prescan measurements to calculate table deflection (displacement and inclination) before the actual imaging process. Based on these calculations, the table driving circuit and tilt driving circuit pre-adjust the table position and gantry angle to compensate for expected deflection. This preliminary correction action ensures accurate image acquisition without requiring post-processing software correction.
2Device complexity
If only one side of the table is supported, then the table structure is simplified, but deflection occurs during sliding leading to displacement and inclination
Solution Approach 1:
The system implements a feedback mechanism where the prescan process measures the actual table deflection (displacement dh and inclination dθ) during sliding. These measurements are fed back to the control system, which then calculates correction values and adjusts the table driving circuit and tilt driving circuit accordingly. This closed-loop feedback ensures high position accuracy is maintained despite the simplified single-sided support structure.
Solution Approach 2:
The system dynamically changes operational parameters (table position, gantry angle) based on measured deflection characteristics. The prescan data provides information about how the table deflects at different positions, and the control system adjusts driving parameters to compensate for these deflections, maintaining imaging precision without requiring a more complex table support structure.
Data Source
AI summary
According to one embodiment, an X-ray CT apparatus includes a gantry, a table on which an object is placed, a bed, and processing circuitry. The gantry is equipped with an X-ray source and an X-ray detector. The bed includes a moving mechanism which is configured to move the table in a horizontal direction and in a vertical direction. The processing circuitry performs a main scan and a prescan. The prescan is performed prior to the main scan. The processing circuitry calculates displacement of the table in the vertical direction and also calculates an angle of the table from the horizontal direction using data acquired in the prescan, and controls a position of the table and an angle of the gantry based on the displacement of the table and the angle of the table.