X-ray Differential Phase Contrast Imaging Correction Method
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Solution Overview
Problem
Grating-based X-ray differential phase contrast imaging (DPCI) is affected by 2π phase-wrapping, leading to prominent line artifacts due to phase offset errors, especially in medical imaging where mechanical rotation of the setup is challenging and double exposure is not acceptable.
Innovation Solution
The proposed solution involves detecting phase wrappings using absorption image information and correcting them by introducing a correction phase offset of 2π radians or its integer multiple at marked 'bad' pixel positions, thereby compensating for the phase offset error in the integrated phase gradient image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase integration is performed in DPCI, then phase gradient information is obtained, but line artifacts appear due to phase wrapping errors
Solution Approach 1:
The method uses feedback from the absorption image to detect and correct phase wrapping errors. By analyzing the absorption image to identify regions with strong phase gradients, the system can detect where phase wrapping occurs and apply corrections to the phase gradient data, thereby eliminating line artifacts while preserving measurement precision.
Solution Approach 2:
The absorption image serves as an intermediary that helps detect phase wrapping errors in the phase gradient image. Instead of directly working with the problematic phase gradient data, the method uses the absorption image as a mediator to identify regions needing correction, then applies corrections to the phase gradient data in those regions.
2Measurement precision
If mechanical rotation of the setup is used to correct phase wrapping, then phase offset errors are compensated, but device complexity and operational difficulty increase
Solution Approach 1:
The method replaces the mechanical rotation system with a computational correction approach. Instead of physically rotating the grating setup to correct phase wrapping, the system uses image processing algorithms to detect and correct phase offset errors in the digital image data, thereby eliminating complex mechanical movements while maintaining correction precision.
Solution Approach 2:
The method creates a corrected version of the phase gradient image by copying the original image and applying computational corrections. Rather than physically repositioning components, the system copies the image data and modifies it algorithmically to compensate for phase wrapping, achieving the same correction effect without mechanical complexity.
3Measurement precision
If double exposure is used to correct phase wrapping, then phase offset errors are compensated, but radiation dose to the patient increases
Solution Approach 1:
The method performs preliminary detection of phase wrapping errors using the absorption image before applying corrections. By pre-identifying regions with strong phase gradients and potential wrapping errors, the system can apply targeted corrections without requiring additional exposure, thereby maintaining measurement precision while avoiding increased radiation dose.
Solution Approach 2:
The method uses the absorption image as a copy or reference to detect phase wrapping errors in the phase gradient image. Instead of requiring a second exposure to correct phase wrapping, the system copies the absorption image information and uses it to identify and correct errors in the phase gradient data, achieving correction without additional radiation dose.
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 enhances the image quality by reducing line artifacts and improving contrast without requiring mechanical rotation or double exposure, making it suitable for medical imaging applications.
Implementation Method 1
after diffracting said X-ray beam at a phase-shifting beam splitter grating
Implementation Method 2
in the resulting Moiré interference pattern of an emitted X-ray beam in the detector plane
Implementation Method 3
the phase between two adjacent pixels in the detected X-ray image varies by more than π radians and is effected by a line integration over the object's local phase gradient
Data Source
AI summary
The present invention generally refers to a correction method for grating-based X-ray differential phase contrast imaging (DPCI) as well as to an apparatus which can advantageously be applied in X-ray radiography and tomography for hard X-ray DPCI of a sample object or an anatomical region of interest to be scanned. More precisely, the proposed invention provides a suitable approach that helps to enhance the image quality of an acquired X-ray image which is affected by phase wrapping, e.g. in the resulting Moiré interference pattern of an emitted X-ray beam in the detector plane of a Talbot-Lau type interferometer after diffracting said X-ray beam at a phase-shifting beam splitter grating. This problem, which is further aggravated by noise in the obtained DPCI images, occurs if the phase between two adjacent pixels in the detected X-ray image varies by more than π radians and is effected by a line integration over the object's local phase gradient, which induces a phase offset error of π radians that leads to prominent line artifacts parallel to the direction of said line integration.