CT Truncation Correction via Phase-Correlated Difference Imaging
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Solution Overview
Problem
Computed tomography (CT) imaging, particularly cone-beam CT, faces challenges with aliasing artifacts such as streaks due to undersampling and respiratory motion, as well as truncation of patient objects like tables, leading to incomplete data and artifacts in reconstructed images.
Innovation Solution
The implementation of a system and method for generating phase-correlated images using truncation correction techniques, including large field-of-view reconstruction and subtraction approaches, and filtering, to address undersampling and truncation issues, which involves extrapolating data beyond the nominal projection space and comparing original and simulated projections to remove artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gantry rotation rate is slowed down to reduce aliasing artifacts, then image quality improves, but imaging time increases and radiation dose increases
Solution Approach 1:
The patent applies preliminary action by performing truncation correction and data completion before final image reconstruction. The system identifies truncated objects, estimates their properties, and completes the incomplete projection data in advance, allowing subsequent reconstruction to proceed without requiring slower gantry rotation to reduce aliasing artifacts.
Solution Approach 2:
The patent uses an intermediary approach by introducing a truncation correction module that acts as a mediator between the raw projection data and the final reconstructed image. This intermediary process completes missing data from truncated objects and removes their artifacts, enabling high-quality reconstruction without the need to slow down the gantry rotation.
2Manufacturing precision
If the gantry rotation rate is slowed down to reduce aliasing artifacts, then image quality improves, but radiation dose increases
Solution Approach 1:
The system performs preliminary truncation correction and data completion before reconstruction, eliminating the need for slower rotation that would increase radiation exposure. By completing the data beforehand, the system achieves high image quality with standard rotation rates and associated lower doses.
Solution Approach 2:
The truncation correction module serves as an intermediary that processes projection data to remove artifacts from truncated objects, enabling high-quality images to be obtained without increasing radiation dose through slower gantry rotation.
3Loss of information
If truncated objects are included in the scanning field, then complete data is acquired, but reconstruction accuracy decreases due to artifacts
Solution Approach 1:
The patent applies the taking out principle by identifying and extracting the contribution of truncated objects from the projection data. The system separates artifacts caused by truncated objects (such as patient tables) from the actual anatomical data, then removes these artifacts while preserving the complete data set for accurate reconstruction.
Solution Approach 2:
The truncation correction module acts as an intermediary that processes the complete projection data, identifying truncated objects and removing their artifact contributions. This allows the system to maintain data completeness while eliminating the negative impact on reconstruction accuracy.
4Area of stationary object
If CBCT is used with wide area detectors to improve field of view, then imaging capability improves, but undersampling problems worsen due to slower frame rates
Solution Approach 1:
The patent applies preliminary action by performing truncation correction and data completion before final reconstruction. This preprocessing step addresses data incompleteness and removes artifacts, compensating for the undersampling issues inherent in CBCT with wide area detectors and slower frame rates.
Solution Approach 2:
The truncation correction module serves as an intermediary that processes the projection data from wide area detectors, correcting for truncation and undersampling effects. This enables the system to maintain the advantages of wide field of view while mitigating the sampling quality degradation.
Data Source
AI summary
In accordance with at least some embodiments of the present disclosure, a process for enhancing an image is presented. The process may include receiving a first plurality of projections, wherein the first plurality of projections contain computed tomography (CT) data obtained in multiple motion phases and also image data attributable to a first portion of a scanned object. The process may include expanding the first plurality of projections to cover at least the first portion of the scanned object to generate a second plurality of projections. The process may further include generating a phase-correlated image based on a multi-phase image and a phase-correlated difference image, wherein the multi-phase image is reconstructed based on the second plurality of projections, and the phase-correlated difference image is reconstructed based on the first plurality of projections and the second plurality of projections.