CBCT Scatter Correction via Measured-Simulated Offset Estimation
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Solution Overview
Problem
Conventional x-ray imaging technologies face challenges in accurately correcting for scattered radiation, particularly from sources outside the field-of-view, leading to artifacts and image quality degradation in cone-beam computed tomography (CBCT) reconstructions.
Innovation Solution
A method and system for estimating and correcting background scatter radiation using a combination of measured and simulated radiation data, involving gain and offset estimation to separate primary and scatter components, allowing for accurate reconstruction of images by modeling radiation transport and accounting for external scatter sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scatter correction methods are used, then object scatter radiation can be corrected, but background scatter radiation from unknown sources cannot be addressed, leading to image artifacts and quality degradation
Solution Approach 1:
The patent introduces an intermediary approach by using measured radiation data from a first pass reconstruction as a mediator to estimate background scatter. The measured radiation serves as an intermediate step that captures both object and background scatter, which then informs the background scatter estimation in the second pass, allowing indirect correction of background artifacts
Solution Approach 2:
The patent applies preliminary action by performing a first pass reconstruction that includes initial scatter correction before the final reconstruction. This preliminary pass generates measured radiation data that is used to estimate background scatter characteristics, which are then applied in the second pass to achieve accurate background scatter correction
2Area of stationary object
If a wide area cone shaped beam is used, then the imaging field-of-view is enlarged, but scattered radiation from external sources increases, introducing artifacts into the image
Solution Approach 1:
The patent segments the scatter radiation into two distinct components: object scatter radiation and background scatter radiation. By separating these components through the two-pass reconstruction method and differential estimation, the system can apply appropriate correction strategies to each segment, allowing wide FOV imaging while correcting for external scatter artifacts
3Area of stationary object
If offset-detector acquisition mode is used to enlarge the imaging field-of-view, then the field-of-view is increased, but scattered radiation from the patient tabletop and other external sources increases, causing dark region artifacts below the scan isocenter
Solution Approach 1:
The patent uses measured radiation from the first pass as an intermediary to estimate background scatter in the offset-detector acquisition mode. This intermediary measurement captures the characteristic dark region artifacts from the patient tabletop, which are then used to inform and correct the background scatter estimation in the final reconstruction
Solution Approach 2:
The patent implements feedback by using the results from the first pass reconstruction (measured radiation) to improve the second pass reconstruction. The measured radiation provides feedback about background scatter characteristics that are fed back into the reconstruction algorithm to correct artifacts in the final image
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 significantly improves image uniformity and accuracy by effectively addressing background scatter, reducing artifacts and enhancing the quality of CBCT reconstructions by isolating and correcting for external scatter radiation.
Implementation Method 1
An x-ray detector may detect both principal radiation and scattered radiation
Implementation Method 2
measured radiation (Im) obtained from a radiation detector that received radiation through an object
Implementation Method 3
simulating the measured radiation obtained from the radiation detector that received radiation through the object, resulting in simulated primary radiation and simulated scatter radiation
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Embodiments include a method, comprising: receiving 200 measured radiation obtained from a radiation detector that received radiation through an object; simulating 202 the measured radiation obtained from the radiation detector that received radiation through the object; generating 206 an offset based on the measured radiation and the simulated measured radiation; estimating 208 scatter radiation based on the offset; and estimating 210 primary radiation based on the estimated scatter radiation.