Compensating X-ray Grid Shadow with Actuator System
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Solution Overview
Problem
Conventional methods for active tracking of X-ray grids in angiography systems are not precise enough to ensure good image quality due to elastic deformation in the device or gantry, causing the focal point of the X-ray emitter to migrate and result in shadowing and visible artifacts in the imaging.
Innovation Solution
A method for controlling a compensation actuator system to compensate the shadow of an X-ray scattered radiation absorption grid in an X-ray image recorded with a pivotably mounted X-ray device, using a computing apparatus to determine a control signal based on motion state data and quality measures to adjust the position of the X-ray grid, thereby optimizing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional active tracking methods using elastostatic models are used to compensate for grid shadow, then the system complexity is reduced and ease of operation is improved, but the measurement precision and manufacturing precision are insufficient leading to visible artifacts
Solution Approach 1:
The patent implements a feedback control mechanism where the actual position of the X-ray emitter is continuously measured and compared with the target position. The control system calculates position deviations and generates correction commands sent to actuators that adjust the grid position in real-time, forming a closed-loop feedback system that significantly improves tracking precision over open-loop conventional methods
Solution Approach 2:
The patent replaces conventional mechanical elastostatic modeling with an electromagnetic field-based measurement and control system. Using electromagnetic sensors to detect emitter position and electronic control systems to process data and generate actuation signals substitutes complex mechanical modeling with more precise electromagnetic field measurements and digital signal processing
2Object-affected harmful factors
If focused rasters with high aspect ratios are used to improve scattered radiation filtering, then image quality is improved, but the system becomes highly sensitive to focal point migration causing strong shadowing artifacts
Solution Approach 1:
The patent transforms the static grid system into a dynamic tracking system where the grid position is continuously adjusted in real-time. The grid follows the migrating focal point of the X-ray emitter through active position control, maintaining optimal alignment despite movements caused by elastic deformation. This dynamic adaptation preserves the high aspect ratio grid's scattering filtering capability while eliminating shadowing artifacts
Solution Approach 2:
The control system performs preliminary position calculations and generates actuation commands before the focal point migration completes. By predicting and compensating for focal point movement in advance, the system maintains grid-emitter alignment proactively rather than reactively, preventing shadowing artifacts before they occur
3Measurement precision
If real-time compensation control is implemented to maintain image quality, then measurement precision is improved, but the computing power and time requirements increase
Solution Approach 1:
The patent implements selective real-time compensation by prioritizing correction of the most significant position deviations and focusing computational resources on critical tracking parameters. The system applies full real-time control only when position deviations exceed threshold values, using simpler correction algorithms for minor deviations, thus reducing overall computing power requirements while maintaining image quality
Solution Approach 2:
The control system operates in periodic cycles, measuring emitter position, calculating deviations, generating correction commands, and actuating the grid at regular time intervals. This periodic operation structure allows the system to balance real-time performance with computing power constraints by processing data in discrete batches rather than continuous computation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides improved image quality in real time with reduced radiation dose by accurately compensating for the shadow of the X-ray grid, enhancing the precision of image tracking and reducing artifacts.
Implementation Method 1
movements caused by elastic deformation in the device or the gantry cause the focal point of the X-ray emitter to migrate
Implementation Method 2
the scattered radiation is filtered out with a scattered radiation raster in front of the image receiver
Data Source
AI summary
A technique for controlling a compensation actuator system for compensating a shadow of an X-ray scattered radiation absorption grid in an X-ray image recorded with a pivotably mounted X-ray device, for example in real time, includes a method with a step of receiving motion state data indicative of a motion state of an X-ray device. The X-ray device is mounted on a pivotable arm. The motion state is assigned to a time of recording of an X-ray image by the X-ray device. A quality measure of the X-ray image with respect to a shadow of an X-ray scattered radiation absorption grid, which is arranged on the detector of the X-ray device, is determined. A control signal for a compensation actuator system for adjusting the position of the X-ray scattered radiation absorption grid is determined depending on the received motion state data and depending on the determined quality measure. Determining the control signal comprises optimizing the quality measure. The control signal determined is output to the compensation actuator system in order to compensate the shadow of the X-ray scattered radiation absorption grid.