Dual-Energy CT Imaging With Cold Cathode Source Synchronization
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Solution Overview
Problem
Existing computed tomography (CT) apparatuses struggle to generate energy subtraction (ES) images in standing or sitting postures due to time lags between radiation emissions, leading to body movement artifacts, and require faster switching between different energy radiation emissions to synchronize projection images.
Innovation Solution
A CT apparatus with a radiation source that emits first and second radiation continuously, a radiation detector that outputs projection images, and a processor that controls these operations to synchronize and generate tomographic images, using a cold cathode field emission type and a displacement mechanism to adjust imaging unit intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two imaging units are disposed at an interval of 90° to obtain first and second projection images at the same time, then the imaging speed is improved, but the imaging angles of the subject are different causing time lag and body movement artifacts
Solution Approach 1:
The imaging system is divided into a first imaging unit and a second imaging unit, each with its own radiation source and radiation detector. These units are disposed at different angular positions (e.g., 90° interval) around the subject, allowing simultaneous acquisition of projection images at different angles without time lag, thereby resolving the contradiction between imaging speed and angular synchronization
Solution Approach 2:
Multiple imaging units are merged into a single integrated CT apparatus with coordinated control. The imaging controller synchronizes the operation of both imaging units so that they acquire projection images simultaneously at their respective angular positions, enabling multi-angle imaging without time lag while maintaining angular precision
2Measurement precision
If projection images are obtained at different rotation positions to compensate for angle differences, then the imaging angles are synchronized, but a time lag occurs between acquisition times affecting unstable subjects
Solution Approach 1:
The imaging system performs periodic acquisition of projection images by both imaging units simultaneously during gantry rotation. The imaging controller coordinates the periodic imaging cycles of both units so that they capture images at the same rotational phase positions, eliminating time lag while maintaining angular synchronization for unstable subjects
Solution Approach 2:
The dual imaging units enable continuous simultaneous acquisition of projection images at multiple angles throughout the rotation cycle. This continuous multi-angle imaging eliminates gaps and time lags between acquisitions, ensuring that both imaging units capture data continuously without interruption or temporal offset
3Device complexity
If switching between first radiation and second radiation is slowed down, then the radiation tube can be simpler, but the synchronism of projection images deteriorates and image quality decreases
Solution Approach 1:
The radiation source is designed with dynamic switching capability that can rapidly alternate between first radiation and second radiation modes. This dynamic switching allows the system to maintain synchronism of projection images even with simpler radiation tube structures, as the switching occurs fast enough to prevent temporal offset between images acquired by different imaging units
Data Source
AI summary
A radiation source includes a radiation tube having a cathode which is a cold cathode. An imaging control unit directs the radiation source to intermittently and alternately emit the first radiation having a first energy distribution and the second radiation having a second energy distribution different from the first energy distribution whenever a rotation mechanism rotates the radiation source and a radiation detector by a preset angle. The imaging control unit directs the radiation detector to output a first projection image based on the first radiation and a second projection image based on the second radiation which are obtained by the intermittent emission of the first radiation and the second radiation. An image processing unit generates a tomographic image on the basis of the first projection image and the second projection image.