X-ray CT Reference Correction for Protrusion Artifacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing X-ray CT apparatus methods for reference correction are inadequate when an object protrudes, as they rely on previous views for calibration, leading to inaccurate normalization with real-time X-ray output changes.
Innovation Solution
A data processing device that calculates a unit air calibration reference value and an estimated reference value based on the X-ray tube current during scanning, normalizes and corrects measured data to account for X-ray output changes, and performs inverse normalization to obtain corrected reference data for accurate reference correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference correction uses data from previous views when protrusion occurs, then protrusion artifacts are reduced, but real-time X-ray output normalization is lost
Solution Approach 1:
The system performs preliminary air calibration to establish baseline reference values before actual scanning. These pre-acquired reference values are stored and used for comparison during scanning to detect protrusion conditions and trigger appropriate correction mechanisms.
Solution Approach 2:
The system continuously monitors reference detector signals during scanning and compares them against expected values. When protrusion is detected through signal deviation, the system provides feedback to switch correction modes - using interpolated values from non-protruding views when needed, while maintaining awareness of real-time X-ray output changes through tube current data.
Solution Approach 3:
The system changes the correction parameter source dynamically - switching between using previous view data (when protrusion detected) and real-time reference data (when no protrusion). Additionally, tube current values are incorporated as a varying parameter to maintain normalization accuracy across different X-ray output conditions.
2Area of stationary object
If reference detectors are used at both ends of the X-ray detector, then reference correction coverage is improved, but vulnerability to object protrusion blocking increases
Solution Approach 1:
The system uses more reference detector channels than the minimum required (one channel), placing detectors at both ends of the X-ray detector array. This excessive placement increases coverage but creates vulnerability to blocking, which is resolved through the protrusion detection and correction mechanisms that identify and compensate for blocked channels.
Solution Approach 2:
The system prepares for potential protrusion blocking by having multiple reference detector channels available and establishing preliminary reference values from air calibration. When blocking is detected, the system can switch to using reference values from non-blocked channels or interpolated values, cushioning against the harmful effect of protrusion.
3Adaptability or versatility
If tube current changes during scanning, then X-ray output adapts to different object densities, but reference correction accuracy deteriorates
Solution Approach 1:
Air calibration is performed beforehand to establish reference values for different tube current settings. This preliminary action creates a lookup table or reference dataset that allows the system to compensate for tube current changes during scanning without losing correction accuracy.
Solution Approach 2:
The system explicitly incorporates tube current as a variable parameter in the reference correction process. By tracking tube current changes and using corresponding reference values from air calibration or interpolated values, the system maintains correction precision despite adapting X-ray output to different object densities.
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 highly accurate reference correction even when an object protrudes in most measurement views, ensuring precise normalization and minimizing artifacts due to X-ray output changes.
Implementation Method 1
An X-ray CT apparatus is an apparatus which applies X-rays from the periphery of an object, collects data regarding the intensity of X-rays transmitted through the object by using an X-ray detector
Implementation Method 2
generates, as an image, information regarding a distribution of an X-ray absorption coefficient of the inside of the object
Implementation Method 3
X-rays which are not transmitted through an object are directly detected by the reference detectors
Data Source
AI summary
In order to provide a data processing device and the like, capable of performing highly accurate reference correction even in a case where an object protrudes in reference channels in most of the measurement views, an image processing device (data processing device) of an X-ray CT apparatus calculates a unit air calibration reference value which is a value per unit tube current of an air calibration reference value which is reference data measured during air calibration, calculates a reference value (estimated reference value) corresponding to an X-ray condition in the main scanning on the basis of an output tube current value in the main scanning and a unit air calibration reference value, and corrects normalized reference data obtained by normalizing a measured reference value in the main scanning with the estimated reference value, to be included in an allowable error range, so as to remove the influence of protrusion.