Variable SID Imaging for CBCT Collision Avoidance
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Solution Overview
Problem
Current medical imaging systems, particularly cone-beam computed tomography (CBCT), face challenges in achieving a large field of view when imaging off-center regions of a patient, leading to potential collisions between the detector and patient, increased x-ray dose, and prolonged procedures due to the need for trial-and-error patient repositioning.
Innovation Solution
A system and method that utilize a gantry with adjustable joints to vary the source-to-image detector distance (SID) based on patient and imaging geometry information, allowing for dynamic adjustment of the detector and source trajectories to optimize the field of view and avoid collisions, thereby enhancing imaging capabilities without increasing detector size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detector is moved away from the center of rotation to reduce collision risk, then the risk of collision between detector and patient is reduced, but the diameter of the reconstructed three-dimensional image field of view is reduced
Solution Approach 1:
The patent applies the dynamics principle by making the source-to-image detector distance (SID) variable rather than fixed. The SID is dynamically adjusted during the imaging procedure based on patient anatomy and imaging requirements. This allows the system to optimize both collision avoidance and field of view diameter by changing the detector position relative to the source during rotation, resolving the contradiction between maintaining safety and preserving imaging coverage.
2Reliability
If trial-and-error patient repositioning is performed to avoid collisions, then collision risk is reduced, but the procedure time is prolonged and additional acquisitions may be required
Solution Approach 1:
The patent applies preliminary action by calculating and determining the optimal imaging geometry and SID adjustments before the actual imaging procedure begins. The system uses patient information and imaging system geometry information to pre-determine the appropriate source-to-image detector distance adjustments, eliminating the need for trial-and-error repositioning during the procedure and reducing overall procedure time.
3Reliability
If the patient is repositioned to avoid collisions, then collision risk is reduced, but the anatomy of interest may lie outside the imaging field of view
Solution Approach 1:
The patent applies parameter changes by modifying the source-to-image detector distance (SID) parameter during imaging. Instead of repositioning the patient, which would change the anatomy coverage, the system changes the SID parameter to adjust the imaging geometry. This allows the patient to remain in the optimal position for anatomy coverage while the variable SID adjustment prevents detector-patient collisions.
4Area of stationary object
If additional acquisitions are performed due to reduced field of view or improper positioning, then complete imaging coverage is achieved, but the x-ray dose is increased
Solution Approach 1:
The patent applies preliminary action by pre-determining the optimal imaging geometry and SID adjustments before imaging begins. By calculating the appropriate source-to-image detector distance modifications in advance based on patient anatomy and the anatomy of interest, the system ensures complete imaging coverage in a single acquisition, eliminating the need for additional x-ray exposures and thereby reducing the total x-ray dose to the patient.
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 improved three-dimensional imaging by increasing the field of view, reducing the risk of collisions, and minimizing radiation dose, while maintaining imaging quality and efficiency.
Implementation Method 1
an x-ray source and an x-ray detector are generally mounted on opposing ends of a substantially C-shaped gantry such that x-rays emitted by the source in a cone-shaped beam are incident on and detectable by the x-ray detector
Implementation Method 2
The C-arm gantry defines an axis of rotation about which the source and detector are rotatable. By positioning this axis of rotation at or near an object, and by rotating the source and detector about the object
Implementation Method 3
At least one of the source and the detector is movably secured to the gantry by an adjustable joint. The gantry controller operates the gantry and the adjustable joint during an imaging procedure to vary a source to image-receptor distance (SID) according to the imaging geometry
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A system 10 for imaging includes a gantry 12 movable relative to a subject 22. A source 14 is configured to emit radiation during an imaging procedure. A detector 18 is configured to receive attenuated radiation from the source 14 during an imaging procedure, at least one of the source 14 and the detector 18 movably secured to the gantry 12 by an adjustable joint 50. An imaging controller 26 is operably connected to at least the gantry 12 and to the adjustable joint 50, wherein the gantry controller 26 receives a priori patient information and imaging system geometry information, the imaging controller 26 determines an imaging geometry and operates the gantry 12 and the adjustable joint 50 to vary a source to image-receptor distance (SID) according to the imaging geometry.