Dental Tomosynthesis Invalidity Matrix Artifact Removal
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Solution Overview
Problem
Conventional intraoral x-ray imaging faces challenges in increasing the field-of-view and reducing noise in two-dimensional images, particularly in dental tomosynthesis, where high contrast variations and patient motion lead to artifacts, and existing solutions either increase radiation dose or fail to achieve high signal-to-noise ratios.
Innovation Solution
The method employs an invalidity matrix and iterative reconstruction to process three-dimensional reconstructed volumes from multiple projection images, removing artifacts and maximizing the field-of-view while maintaining noise levels comparable to standard radiographs, by deweighting problematic pixels and interpolating marker particle contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the field-of-view of an intraoral sensor is increased to capture more teeth or larger anatomical regions, then the diagnostic coverage is improved, but the physical size of the sensor must be increased which is prohibitive due to limited intraoral space and patient discomfort
Solution Approach 1:
The patent transitions from a two-dimensional sensor plane to a three-dimensional reconstructed volume by acquiring multiple projection images at different source positions and angles. This volumetric approach allows the system to capture a larger effective field-of-view by synthesizing information from multiple perspectives rather than relying on a single large-area sensor.
Solution Approach 2:
The patent introduces marker particles as intermediary objects that facilitate the measurement and correction of system geometry and patient motion. These markers enable accurate registration and alignment of multiple projections, which is essential for constructing the extended field-of-view volume without requiring a physically larger sensor.
2Area of stationary object
If conventional reconstruction methods are used to increase the reconstructed volume, then the field-of-view is extended, but significant stitching artifacts and misalignment between subvolumes occur due to system geometry variations and patient motion
Solution Approach 1:
The patent employs an iterative reconstruction process where the system geometry and patient motion are continuously measured and corrected using marker particle data. The measured geometric parameters and motion trajectories provide feedback that is used to adjust the reconstruction algorithm, ensuring accurate alignment of multiple subvolumes and minimizing stitching artifacts.
Solution Approach 2:
The patent dynamically adjusts reconstruction parameters based on measured system geometry and patient motion. By varying the reconstruction parameters according to the actual imaging conditions rather than using fixed parameters, the system achieves accurate alignment and reduced artifacts across the extended field-of-view volume.
3Loss of information
If additional projection images are acquired to extend the field-of-view, then the diagnostic information is improved, but the radiation dose to the patient increases
Solution Approach 1:
The patent optimizes the acquisition parameters including the number of projections, scan angle range, and source-to-detector distance to achieve the desired field-of-view extension with minimal radiation dose. By carefully selecting and adjusting these parameters, the system balances diagnostic information quality with patient radiation exposure.
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 allows for a two-dimensional image with an extended field-of-view and noise comparable to standard radiographs, reducing the need for additional high-dose imaging and minimizing radiation exposure, while effectively handling high contrast dental anatomy.
Implementation Method 1
X-ray radiography can be performed by positioning an x-ray source on one side of an object (e.g., a patient or a portion thereof) and causing the x-ray source to emit x-rays through the object and toward an x-ray detector located on the other side of the object. As the x-rays pass through the object from the x-ray source, their energies are absorbed to varying degrees depending on the composition of the object, and x-rays arriving at the x-ray detector form a two-dimensional x-ray image (also known as a radiograph) based on the cumulative absorption through the object.
Implementation Method 2
The computer system then performs iterative reconstruction of a three-dimensional volume of the irradiated dental anatomy based on the acquired projection images
Implementation Method 3
The reprojection of the final reconstructed volume is performed by determining a reprojection surface and projecting the final reconstructed volume onto the reprojection surface to obtain a two-dimensional image with an extended field of view
Data Source
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AI summary
A method, apparatus, system, and computer program product for using an invalidity matrix, iterative reconstruction and reprojection to generate a two-dimensional image. The method includes acquiring projections through an a dental anatomy, calibrating the acquired projected images, estimating a geometry of the tomosynthesis system, determining an invalidity matrix for each acquired projection image, removing contributions of marker particles to the acquired projection images, constructing a starting volume for reconstruction, performing an iteration process for iteratively updating the starting volume, and reprojecting a final reconstructed volume to obtain a final two-dimensional image.