Cosine Correction for Photon Counting Detector Pixel Inhomogeneity
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Solution Overview
Problem
Photon counting detectors in medical imaging suffer from uneven response among pixels, leading to artifacts in reconstructed images, which conventional flat field correction techniques poorly address.
Innovation Solution
A method and system for data correction that involves obtaining spatial positions of detector pixel units, determining cosine correction data, calculating response data corrections using these positions, and applying correction coefficients to improve response uniformity and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat field correction technique is used to correct detector pixel response data, then the correction process is simple, but the response uniformity of detector pixels is poorly improved
Solution Approach 1:
The patent introduces cosine correction coefficients as a new parameter to multiply the flat field correction coefficients. This parameter change transforms the correction formula from a simple additive model to a multiplicative model that accounts for the angular distribution of incident photons, thereby improving response uniformity while maintaining computational feasibility
Solution Approach 2:
The patent pre-calculates cosine correction coefficients for each detector pixel based on its spatial position and the X-ray source geometry before actual imaging. This preliminary action allows the correction to be applied systematically during reconstruction without adding complexity to the real-time correction process
2Ease of operation
If conventional flat field correction is applied, then the correction method is straightforward, but artifacts in reconstructed images are not effectively reduced
Solution Approach 1:
The patent modifies the correction parameters by introducing cosine-based weighting factors that reflect the actual angular distribution of X-ray photons incident on each detector pixel. This parameter enhancement allows the correction method to account for geometric effects that conventional flat field correction ignores, thereby reducing artifacts while maintaining operational simplicity
Solution Approach 2:
The patent introduces cosine correction coefficients as an intermediary element between the raw detector data and the final corrected image. These coefficients mediate the correction process by systematically adjusting for angular variations in photon incidence, thereby eliminating artifacts without complicating the overall workflow
3Productivity
If detector pixel response inhomogeneity is not corrected, then the processing is fast, but the reconstructed image quality is poor with high noise and artifacts
Solution Approach 1:
The patent performs cosine correction coefficient calculation during the pre-processing or calibration phase, storing these coefficients for later application. This preliminary action separates the computationally intensive correction setup from the actual imaging process, maintaining fast processing speed during scanning while ensuring high image quality through systematic correction
Solution Approach 2:
The patent transforms the correction approach by introducing angular-dependent parameters that are calculated once based on detector geometry and then applied consistently across all projections. This parameter transformation enables fast processing during actual imaging while maintaining high measurement precision through geometrically accurate correction
Data Source
AI summary
The embodiments of the present disclosure provide a method and system for data correction. The method is applied to a medical scanning device including a ray emitting device and a detector. The detector may include a plurality of detector pixel units. The method for data correction may include obtaining spatial positions of the plurality of detector pixel units; determining cosine correction data based on the spatial positions of the plurality of detector pixel units and a spatial position of a focal point of the ray emitting device; determining response data to be corrected of the detector; determining target data by correcting the response data to be corrected using the cosine correction data; determining one or more correction coefficients corresponding to the plurality of detector pixel units based on the target data; and correcting response data of a subject to be detected based on the one or more correction coefficients.