X-ray Recording System Automatic Positioning via Intercept Theorem
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Solution Overview
Problem
Precise positioning of a subarea in an examination object, such as a vertebral body, is challenging due to the unknown distance between the x-ray source and the object, leading to inaccurate centering, as existing methods rely on assumptions or additional reference objects.
Innovation Solution
A method that involves acquiring two x-ray images, determining the relative pixel distance between the subarea of interest on both images, and calculating the x-ray source-subarea distance using the intercept theorem, allowing for automatic adjustment of the recording system for precise positioning without additional reference objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the SOD is unknown and an average value is assumed for positioning, then the positioning process is simple, but the centering accuracy of the subarea deteriorates
Solution Approach 1:
The patent replaces manual positioning operations with an automated image processing system. The system automatically calculates the SOD based on pixel distances from two images and computes the required displacement, eliminating the need for manual measurement and assumption of average values, thereby achieving both operational simplicity and high precision.
Solution Approach 2:
The system performs self-positioning by automatically determining the SOD and calculating the necessary displacement of the recording system. The system uses its own captured images to compute the pixel distance ratio and derives the SOD without requiring external reference objects or manual intervention, enabling precise autonomous centering of the subarea.
2Ease of operation
If ultrasound sensors or time-of-flight sensors are used to measure distance, then the measurement process is simplified, but the precision of SOD measurement deteriorates because they measure distance from the patient body surface, not from the specific subarea
Solution Approach 1:
The patent replaces physical distance sensors (ultrasound or time-of-flight sensors) with an optical/image-based measurement system. By capturing x-ray images and calculating pixel distances between the subarea and detector, the system derives the SOD through geometric relationships, achieving precise measurement of the distance to the specific subarea rather than just the body surface.
Solution Approach 2:
The patent introduces the x-ray detector as an intermediary element that enables precise SOD measurement. The detector captures images of the subarea, and through pixel distance measurements in these images, the system indirectly determines the SOD with high precision, overcoming the limitation of direct sensor measurements that only reach the body surface.
3Measurement precision
If standardized reference objects are used to determine distances, then the measurement process becomes systematic, but the device complexity and workflow time increase
Solution Approach 1:
The patent extracts the measurement function from external reference objects and integrates it directly into the imaging process. By using the subarea itself as the reference point in the captured images and calculating pixel distances from the detector, the system eliminates the need for separate standardized reference objects, reducing device complexity while maintaining systematic and precise distance determination.
Solution Approach 2:
The patent makes the x-ray detector serve multiple functions: it both captures diagnostic images of the subarea and simultaneously provides the measurement scale for determining the SOD. The pixel distances in the same image serve dual purposes for both diagnostic visualization and quantitative distance measurement, eliminating the need for separate reference objects and reducing overall system complexity.
Data Source
AI summary
A method and system are provided for the automatic positioning of a recording system with an x-ray detector and an x-ray source with respect to a subarea of an examination object. A x-ray source to examination object distance is calculated from a displacement distance, the relative pixel distance and the known x-ray source to x-ray detector distance. The x-ray source to examination object distance is used for automatic positioning of the recording system.