X-ray CT Controller Exposure State Feedback
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Solution Overview
Problem
Existing X-ray CT apparatuses face challenges in accurately determining whether projection data is collected during X-ray exposure, leading to errors in image reconstruction and dose calculation, especially due to variations in reference detector count values and unstable X-ray tube conditions.
Innovation Solution
The X-ray CT apparatus includes a controller that adds additional information about X-ray exposure state to each projection data set, allowing precise determination of exposure timing and voltage/current values, ensuring accurate collection of data during X-ray exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference detector is used to determine X-ray exposure state, then exposure timing can be identified, but determination accuracy deteriorates due to detector variations and X-ray tube instability
Solution Approach 1:
The system uses the actual X-ray output value (mA value) detected during exposure as feedback to determine whether projection data was collected during X-ray exposure. This feedback mechanism replaces the unreliable reference detector threshold method with direct measurement of the actual exposure condition, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent introduces an intermediary parameter (actual X-ray output value/mA value) that mediates between the X-ray tube output and the projection data collection status. This intermediary provides a reliable indicator of exposure state that is not affected by reference detector variations or offset values.
2Ease of operation
If threshold-based determination is used for Ref detector count values, then exposure state can be classified, but measurement accuracy deteriorates due to individual detector differences and offset values
Solution Approach 1:
The system changes the parameter used for exposure determination from reference detector count values to actual X-ray output values (mA values). This parameter change eliminates the problems of individual detector differences and offset values, as the actual output value directly reflects the X-ray tube's exposure state without requiring threshold classification.
3Adaptability or versatility
If X-ray output is modulated during scanning, then imaging flexibility increases, but dose calculation accuracy deteriorates because actual mA values cannot be determined
Solution Approach 1:
The patent replaces the mechanical/threshold-based determination system with an electrical measurement system that directly reads the actual X-ray output value (mA value). This substitution allows accurate dose calculation even when X-ray output is modulated, as the actual instantaneous mA value is measured and recorded for each projection data set.
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 enables more accurate determination of X-ray exposure states, ensuring only valid projection data is used for image reconstruction and allowing precise calculation of exposure dose, even during modulated X-ray output and unstable tube conditions.
Implementation Method 1
an X-ray generator; an X-ray detector, arranged opposite to said X-ray generator by sandwiching a subject, configured to collect, as projection data, X-rays that have been exposed from said X-ray generator
Implementation Method 2
an X-ray detector, arranged opposite to said X-ray generator by sandwiching a subject, configured to collect, as projection data, X-rays that have been exposed from said X-ray generator and transmitted through said subject
Data Source
AI summary
An X-ray CT apparatus includes an X-ray generator and an X-ray detector. The X-ray generator and the X-ray detector rotate about a subject. A controller controls the timing of exposing X-rays from the X-ray generator. The controller controls the collection timing for the projection data used by the X-ray detector and causes the X-ray detector to continuously collect the projection data at the specified collection timing. The controller causes additional information representing the state of exposure of the X-rays to be added to each projection data that has been collected by the X-ray detector at said specified collection timing.