X-ray CT Reference Frame Sensor Calibration
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Solution Overview
Problem
The geometrical positional relationship between the X-ray source, detector, and rotating table in X-ray CT apparatuses changes due to heat generation and environmental variations, affecting image quality and precision.
Innovation Solution
Incorporating a reference frame and sensors to continuously monitor and adjust the geometrical positional relationship during the CT scan, using displacement meters, cameras, or laser interferometers to obtain calibration values for improved precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed in advance for the geometrical positional relationship, then measurement precision is improved, but the precision deteriorates due to heat generation and environmental changes during operation
Solution Approach 1:
The patent applies preliminary action by performing calibration before measurement and storing calibration values. The calibration establishes the initial geometrical positional relationship between the X-ray source, detector, and rotating table, which is saved and used as a reference for subsequent measurements.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual geometrical positional relationship during CT scanning using sensors (displacement meters, cameras, or laser interferometers). The monitored values are compared with calibration values, and correction is applied based on the deviation detected, thereby maintaining measurement precision despite environmental changes.
2Measurement precision
If continuous monitoring and adjustment is implemented, then measurement precision is maintained, but device complexity increases
Solution Approach 1:
The patent introduces intermediary components (sensors such as displacement meters, cameras, or laser interferometers) that mediate between the geometrical positional relationship and the control system. These sensors detect positional deviations and transmit information to the arithmetic control unit, which processes the data and applies corrections without requiring direct manual intervention.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms with sensor-based detection and computational correction. Instead of using mechanical devices to physically adjust and maintain positional relationships, the system uses optical or electromagnetic sensors to detect deviations and applies software-based corrections during image reconstruction.
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
Enables high-precision X-ray CT measurements of entire objects, including internal structures, by reducing the impact of positional changes, thereby enhancing the quality and accuracy of volume data.
Implementation Method 1
laser interferometers to obtain calibration values
Implementation Method 2
The X-ray source 12 emits X-rays. An example of the X-ray source 12 is an X-ray tube. The X-ray detector 14 detects an X-ray beam 13 that is emitted from the X-ray source 12 and transmitted through the periphery and interior of a work 10
Data Source
AI summary
A measurement X-ray CT apparatus calibrates a geometrical positional relationship between a focus of an X-ray source, an X-ray detector, and a rotation center of a rotating table in advance. The measurement X-ray CT apparatus then obtains projection images by irradiating the object to be measured with X-rays to perform a CT scan, and generates a three-dimensional image of the object to be measured by CT reconstruction of the projection images. The measurement X-ray CT apparatus further includes a reference frame that is made of a material and has a structure less susceptible to environmental changes, and sensors that are located on the reference frame and intended to successively obtain calibration values of the geometrical positional relationship between the focus of the X-ray source and the X-ray detector during the CT scan. The calibration values are used as parameters of the CT reconstruction.