Radiography System Marker-Based Cassette Positioning
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Solution Overview
Problem
In free imaging using electronic cassettes, it is challenging to accurately position the cassette relative to the subject when the cassette is covered, as existing techniques require capturing the cassette's image in the same field of view without the patient or require knowledge of the source image distance, which is impractical in emergency situations or when the cassette is between the patient and the bed.
Innovation Solution
A radiography system comprising a radiation source, an electronic cassette, a camera attached to the radiation source, a position detection unit, a calculation unit, and a display controller that generates a composite image to display the cassette's position within the camera image, allowing for accurate positioning even when the cassette is covered by the subject.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electronic cassette is inserted between the patient and the bed for free imaging, then the mobility and accessibility of the imaging system is improved, but the cassette may be covered by the patient making positioning difficult
Solution Approach 1:
A marker is introduced as an intermediary element that is attached to the electronic cassette and can be detected by the camera even when the cassette itself is covered by the patient. This marker serves as a mediator that bridges the gap between the hidden cassette and the camera's field of view, enabling position detection without requiring direct visibility of the cassette.
Solution Approach 2:
Instead of directly detecting the cassette's position when it is hidden, the system creates a visual representation (copy) of the cassette's position through the marker's position in the camera image. The marker acts as a visual proxy that replicates the cassette's spatial information, allowing the operator to infer the cassette's position from the marker's visible location.
2Measurement precision
If the cassette position is detected using existing techniques requiring the cassette to be visible or knowing the source image distance, then the positioning accuracy is improved, but the ease of operation deteriorates in emergency situations
Solution Approach 1:
The electronic cassette performs self-positioning by automatically detecting its own position through the marker's image captured by the camera. The calculation unit automatically computes the cassette's position based on the marker's coordinates in the camera image, eliminating the need for manual positioning or complex measurements by the operator. This self-service mechanism maintains high positioning accuracy while greatly simplifying operation.
Solution Approach 2:
The system changes the detection parameter from requiring direct visibility of the cassette or knowledge of source image distance to detecting the marker's position in the camera image. This parameter transformation allows position detection to proceed under different conditions (marker visibility instead of cassette visibility), improving ease of operation in emergency situations while maintaining measurement precision through mathematical calculation of the cassette's actual position from the marker's image coordinates.
3Loss of information
If the camera captures the cassette image in the same field of view without the patient, then the positioning information is improved, but the adaptability to emergency situations deteriorates
Solution Approach 1:
The system segments the positioning function into two independent parts: a marker attached to the cassette that provides position information, and a calculation unit that processes the marker's image coordinates to determine the cassette's position. This segmentation allows the marker to be detected independently of the cassette's visibility, enabling positioning information to be obtained even when the patient blocks the cassette from the camera's view during emergency imaging.
Data Source
AI summary
A position detection unit is disposed at an exposure position that is included in a camera image and a field of view of a camera and outputs a position signal indicating the position of a part of a peripheral portion of an electronic cassette. The calculation unit calculates an in-image cassette position which is the position of the electronic cassette in the camera image, on the basis of the position, direction, and size of the position detection unit in the camera image and the position signal. A composite image generation unit generates a composite image of the camera image and a cassette frame indicating the in-image cassette position. A display controller displays the composite image on a touch panel.