X-ray Collimator Adjustment Using Optical Axis Offset Compensation
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Solution Overview
Problem
In x-ray systems where the central x-ray axis and the optical axis of an imaging device are not congruent, existing methods for adjusting collimator elements result in unnecessary radiation exposure to patients due to the inability to accurately compute collimator positions from two-dimensional images.
Innovation Solution
A method and system for collimator element adjustment that involves displaying a recorded optical image, marking a target region, determining collimator element position values based on the marked region and geometrical parameters, and adjusting the collimator elements using a computer-controlled mechanism, accounting for the difference between the central x-ray axis and the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automatic collimator positioning is performed based on marked target region in optical image, then collimator adjustment efficiency is improved, but patient radiation exposure increases due to inability to accurately compute positions from 2D images
Solution Approach 1:
The patent performs preliminary computational geometry calculations to establish the relationship between optical image coordinates and x-ray source coordinates before actual collimator adjustment. By pre-computing the offset between optical axis and central x-ray axis and storing transformation parameters, the system enables accurate collimator positioning without requiring additional patient radiation for verification or adjustment iterations.
2Loss of time
If collimator element position is computed automatically from marked target region, then adjustment time is reduced, but positioning accuracy deteriorates due to axis misalignment between optical and x-ray systems
Solution Approach 1:
The patent explicitly accounts for the asymmetric offset between the optical axis of the imaging device and the central x-ray axis of the x-ray source. By incorporating this known geometric asymmetry into the coordinate transformation algorithm, the system maintains high positioning accuracy despite the inherent misalignment, enabling fast automatic adjustment without compromising precision.
Solution Approach 2:
The patent introduces an intermediary coordinate transformation system that bridges the optical image coordinate system and the x-ray source coordinate system. This transformation layer, based on pre-measured geometric parameters including axis offset and magnification factors, accurately maps target region coordinates from the optical image to the corresponding collimator element positions, resolving the positioning accuracy issue while maintaining fast automatic adjustment.
Data Source
AI summary
A method is for collimator element adjustment of an x-ray system with a central x-ray axis and an optical axis of an optical imaging device differing therefrom. In an embodiment, the method includes displaying a first recorded optical image of the examination object; marking a target region as a region to be shown in the displayed first recorded optical image; determination of at least one first collimator element position value based on the marked target region in the first recorded optical image; and adjustment of the collimator element position with the at least one first collimator element position value determined.