Dynamic Collimator Adjustment for X-Ray Dose Reduction
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Solution Overview
Problem
Existing medical imaging devices, particularly Cone Beam Computed Tomography (CBCT) scanners, face challenges in maintaining image accuracy and reducing radiation dose due to patient movement during scans, as current fixation methods are uncomfortable and often result in larger defined regions of interest to account for potential movement, leading to increased radiation exposure.
Innovation Solution
A method using a tracking element with fiducial markers and cameras to monitor patient movement, allowing for real-time adjustment of the collimator to confine x-ray exposure to a defined region of interest, thereby reducing unnecessary radiation and improving image accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If head fixation devices are used to minimize patient movement, then image accuracy is improved, but patient comfort deteriorates
Solution Approach 1:
The patent replaces mechanical fixation devices with an optical tracking system using cameras to monitor patient movement. The camera system captures images of fiducial markers on the patient, and software algorithms calculate movement, eliminating the need for physical restraints while maintaining image accuracy through dynamic ROI adjustment.
2Reliability
If a larger region of interest is defined to account for patient movement, then coverage of the target area is improved, but radiation dose increases
Solution Approach 1:
The patent implements dynamic adjustment of the region of interest based on real-time patient movement tracking. The ROI is continuously updated according to the patient's actual movement, allowing the system to maintain accurate coverage of the target area while minimizing the scanned volume and reducing radiation dose compared to static, oversized ROI definitions.
Solution Approach 2:
The system uses feedback from camera tracking of fiducial markers to continuously monitor patient movement and adjust the ROI accordingly. This closed-loop feedback mechanism ensures the ROI remains optimally sized to cover the target area while minimizing unnecessary radiation exposure to surrounding regions.
3Object-affected harmful factors
If fewer images are taken to reduce radiation dose, then radiation exposure is reduced, but reconstruction quality deteriorates
Solution Approach 1:
The patent applies local quality by concentrating imaging resources on the dynamically defined region of interest rather than uniformly scanning a larger area. By restricting the x-ray beam to only the necessary ROI based on real-time patient position, the system achieves high reconstruction quality for the target area while reducing overall radiation dose.
4Device complexity
If the region of interest is defined schematically without real-time tracking, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces fiducial markers as intermediaries between the patient and the imaging system. These markers serve as reference points that the camera system tracks to determine patient movement, providing precise measurement data without requiring complex direct patient monitoring systems.
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 approach enables precise focusing of x-rays on the region of interest, reducing patient radiation dose and improving image quality by compensating for patient movement during scans, allowing for smaller, more accurately defined regions of interest.
Implementation Method 1
obtaining at least two tracking images of a tracking element taken with at least one camera
Implementation Method 2
obtaining at least one medical image of the region of interest after the adjustment of the medical imaging device
Data Source
AI summary
Disclosed herein is a method of reducing the x-ray dose of a patient in an x-ray system, comprising defining a region of interest of the patient, obtaining at least two tracking images of a tracking element taken with at least one camera having a known positional relationship relative to an x-ray source and/or sensor, determining any movement of the tracking element between the acquisition of at least two tracking images, adjusting the collimator of the x-ray source to compensate for any movement of the tracking element between the acquisition of the at least two tracking images, providing that the field of exposure of the x-ray source is confined to the region of interest and obtaining at least one x-ray image of the region of interest after the adjustment of the collimator.