X-ray CT Localizer Image Pixel Dimension Control
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Solution Overview
Problem
The existing X-ray CT apparatuses face image degradation and errors in tube current calculation due to varying pixel dimensions in localizer images, especially when scanning ranges change, leading to inaccuracies in auto exposure control.
Innovation Solution
The X-ray CT apparatus generates localizer images with constant pixel dimensions irrespective of scanning ranges by adjusting matrix sizes based on scanning range dimensions, using appropriate image processing filters for accurate tube current calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide scanning range is used to capture localizer images, then the coverage area is improved, but the pixel dimension varies and causes image degradation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the matrix size based on the scanning range. When the scanning range changes, the system recalculates and sets an appropriate matrix size to maintain constant pixel dimension. This resolves the contradiction by changing the matrix size parameter in response to scanning range variations, ensuring that pixel dimension remains stable regardless of whether a wide or narrow scan is performed.
2Adaptability or versatility
If the pixel dimension varies with scanning range, then the scanning flexibility is improved, but the tube current calculation accuracy deteriorates
Solution Approach 1:
The system maintains scanning flexibility while ensuring measurement precision by dynamically adjusting the matrix size parameter. The control unit calculates and sets an appropriate matrix size based on the scanning range, which ensures that the pixel dimension remains constant. This constant pixel dimension is crucial for accurate tube current calculation by the AEC unit, thereby resolving the contradiction between scanning flexibility and calculation accuracy.
Solution Approach 2:
The system implements feedback by continuously monitoring the scanning range and adjusting the matrix size accordingly. The control unit receives information about the scanning range, calculates the appropriate matrix size, and sets it before the localizer scan. This feedback mechanism ensures that the pixel dimension remains constant regardless of scanning range variations, maintaining both flexibility and accuracy in tube current calculation.
3Device complexity
If a fixed matrix size is used for all scanning ranges, then the processing simplicity is improved, but the image quality for different scan ranges becomes inconsistent
Solution Approach 1:
The patent resolves this contradiction by implementing dynamic matrix size adjustment based on scanning range. Rather than using a fixed matrix size, the system calculates and sets an appropriate matrix size for each scanning range. This maintains processing simplicity while ensuring image quality consistency, as the matrix size is automatically adapted to match the scanning range, preventing image degradation in wide scans while maintaining detail in narrow scans.
Data Source
AI summary
An X-ray computed tomography (CT) apparatus according to an embodiments includes collection circuitry, control circuitry and image generation circuitry. The collection circuitry collects a signal derived from X-rays emitted from an X-ray tube and transmitted through a subject. The control circuitry calculates a value of tube current to be supplied to the X-ray tube in a main scan, based on a first image acquired through a reconstruction process using the signal and a first filter, the signal being collected by the collection circuitry in a localizer scan. The image generation circuitry generates a second image as a localizer image through a reconstruction process using the signal and a second filter, the signal being collected by the collection circuitry in the localizer scan.