X-Ray Tube-Detector Alignment Using Electromagnetic Tracking
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Solution Overview
Problem
In X-ray imaging systems, particularly mobile DR applications, accurate alignment of the tube with the detector plate is hindered by the patient obstructing the view, leading to poor positioning precision and inaccurate alignment methods such as inertial navigation, RF transmitters, ultrasonic positioning, and machine vision, which are not precise enough for clinical applications.
Innovation Solution
An electromagnetic tracking apparatus is used to acquire the detector plate's coordinates in a magnetic field coordinate system, transforming these to a 3D camera's image coordinate system, and aligning the tube by controlling exposure and monitoring the light field of X-rays, ensuring precise alignment through electromagnetic tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the patient is positioned for imaging, then the imaging procedure can be performed, but the detector plate becomes obscured and alignment verification becomes impossible
Solution Approach 1:
The patent introduces electromagnetic tracking technology as an intermediary system. A magnetic field generator is placed on the tube and magnetic sensors on the detector plate, allowing alignment verification through electromagnetic field interaction rather than direct visual observation. This mediator enables the technician to verify alignment through coordinate system transformation and position display without needing to see the obscured detector plate.
2Measurement precision
If conventional positioning methods (inertial navigation, RF transmitters, ultrasonic positioning) are used, then alignment can be attempted, but positioning precision is insufficient (error > 10 cm)
Solution Approach 1:
The patent replaces mechanical positioning systems (inertial sensors, RF transmitters, ultrasonic devices) with an electromagnetic tracking system. The magnetic field-based tracking provides superior precision by using coordinate system transformation between the tube and detector plate, achieving sub-centimeter accuracy compared to the 10 cm error of conventional methods.
3Measurement precision
If the technician manually aligns the tube and detector plate without assistance, then the process is simple, but alignment accuracy is poor due to inability to verify position
Solution Approach 1:
The patent implements a feedback system where the electromagnetic tracking apparatus continuously monitors the relative position between the tube and detector plate. The system transforms coordinates from the detector plate's coordinate system to the tube's coordinate system and displays the position information, providing real-time feedback to the technician for precise alignment adjustment.
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
This method achieves high-precision alignment of the tube and detector plate, even when obscured by a patient, enhancing the accuracy and efficiency of X-ray imaging systems.
Implementation Method 1
acquiring coordinates of the center of the detector plate in a magnetic field coordinate system by means of an electromagnetic tracking apparatus, wherein a magnetic field transmitter of the electromagnetic tracking apparatus is fixed to a casing of the tube, and a magnetic sensor of the electromagnetic tracking apparatus is fixed in a non-imaging region of the detector plate
Data Source
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AI summary
Embodiments of the present invention disclose a method and apparatus for alignment of a tube and a detector plate in an X-ray imaging system, and a system. The method comprises: acquiring coordinates of the center of the detector plate in a magnetic field coordinate system by means of an electromagnetic tracking apparatus, wherein a magnetic field transmitter is fixed to a casing of the tube, and a magnetic sensor is fixed in a non-imaging region of the detector plate; transforming the coordinates of the center of the detector plate to a two-dimensional image coordinate system of a 3D camera; controlling the X-ray imaging system to begin exposure; during exposure, moving the tube and acquiring in real time the center of a light field of X-rays collected by the 3D camera; transforming the center of the light field of X-rays to the two-dimensional image coordinate system of the 3D camera; when the center of the light field of X-rays coincides with the center of the detector plate in the two-dimensional image coordinate system, determining that the tube and the detector plate have attained center alignment. Embodiments of the present invention increase the probability of accurate alignment of the tube and the detector plate.