Asymmetric Scatter Fitting for Faster Cone-Beam CT Readout
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Solution Overview
Problem
Scatter in cone-beam CT imaging negatively impacts image quality and quantitative accuracy, particularly in the absence of anti-scatter grids, and conventional scatter estimation methods require significant data from both sides of the collimator shadows, which can prolong scanning time.
Innovation Solution
Estimate scatter in primary region projection data using measured data from shadow regions of the detector, where one side of the collimator shadow region is offset from the readout center, allowing for asymmetric scatter fitting to reduce the detector readout range and increase scanning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data from both sides of collimator shadows is collected for scatter fitting, then scatter estimation accuracy is improved, but detector readout time increases and scanning efficiency decreases
Solution Approach 1:
The patent extracts only the necessary shadow region data from one side of the collimator shadow for scatter fitting, rather than collecting data from both sides. This selective extraction maintains adequate scatter estimation accuracy while reducing the amount of data that needs to be read from the detector, thereby decreasing readout time and improving scanning efficiency.
2Productivity
If reduced detector readout range is used, then readout time is reduced and frame rate increases, but scatter estimation reliability may be compromised
Solution Approach 1:
The patent applies local quality by selectively reading shadow region data only where needed for scatter estimation, rather than reading the entire detector range. By focusing readout on specific shadow regions that provide sufficient scatter fitting information, the system achieves reliable scatter estimation with a reduced readout range, thereby increasing frame rate without compromising reliability.
3Productivity
If asymmetric shadow region data is used for scatter fitting, then readout range is optimized and scanning efficiency improves, but conventional symmetric fitting methods become inapplicable
Solution Approach 1:
The patent deliberately employs asymmetric shadow region data collection, reading shadow data from only one side of the collimator shadow rather than symmetrically from both sides. This asymmetric approach optimizes the readout range and improves scanning efficiency. The scatter fitting algorithm is accordingly adapted to handle the asymmetric data configuration, providing a practical balance between efficiency and method complexity.
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
Improves image quality and reduces scanning time by accurately estimating scatter without the need for extensive data from both sides of the collimator shadows, maintaining or increasing the scanning field-of-view while allowing higher frame rates.
Implementation Method 1
receiving measured projection data from a primary region of an x-ray detector, wherein the primary region of the x-ray detector is directly exposed to a radiation beam from a radiation source
Implementation Method 2
receiving measured scatter data from at least one shadow region of the x-ray detector, wherein the at least one shadow region of the x-ray detector is blocked from direct exposure to the radiation beam
Data Source
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AI summary
An x-ray imaging apparatus and associated methods are provided to receive measured projection data in a primary region and measured scatter data in asymmetrical shadow regions and determine an estimated scatter in the primary region based on the measured scatter data in the shadow region(s). The asymmetric shadow regions can be controlled by adjusting the position of the beam aperture center on the readout area of the detector. Penumbra data may also be used to estimate scatter in the primary region.