CT Image Reconstruction with Motion Artifact Correction
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Solution Overview
Problem
Conventional CT imaging systems face challenges in efficiently reconstructing moving objects like the heart and large fields of view while minimizing x-ray dose, particularly in cardiac screening, due to excessive radiation exposure and inadequate tube current modulation techniques.
Innovation Solution
The method involves performing first and second reconstructions based on attenuation measurements, where the second reconstruction utilizes EKG gating information to correct for motion artifacts, and combines central and peripheral portions of the reconstruction data sets, while the first reconstruction does not, using a detector with nonuniform cross-sections to optimize x-ray energy application and reduce radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CT systems perform multiple scans to obtain sufficient projection data sets for cardiac reconstruction, then image reconstruction accuracy is improved, but patient radiation exposure increases
Solution Approach 1:
The detector is divided into multiple independent rows, allowing selective exposure of only those rows necessary for cardiac imaging. This segmentation enables the system to acquire sufficient projection data for accurate cardiac reconstruction while limiting radiation exposure to a smaller portion of the patient's body, thereby resolving the contradiction between image accuracy and radiation dose.
Solution Approach 2:
The patent applies different exposure strategies to different detector rows based on their specific utility for cardiac imaging. Central detector rows that capture cardiac information are fully exposed, while peripheral rows are partially or completely excluded. This local differentiation optimizes the balance between obtaining sufficient data for accurate reconstruction and minimizing overall radiation exposure.
2Area of stationary object
If CT systems use large detectors to obtain information regarding larger regions of interest, then field of view is improved, but overall radiation dosage increases
Solution Approach 1:
The large detector is segmented into multiple rows, enabling the system to activate only the necessary portion for the current imaging task. When imaging the heart, only central detector rows are activated. When imaging surrounding anatomy like lungs, different rows can be selected. This segmentation allows the system to maintain a large physical detector for versatile field of view while controlling radiation dosage by activating only required segments.
Solution Approach 2:
The system dynamically adjusts which detector rows are active based on the specific imaging requirements. For cardiac studies, only central rows are exposed; for other examinations, different row configurations can be used. This dynamic adaptability allows the same physical detector to serve multiple purposes with optimized radiation exposure for each specific application.
3Measurement precision
If tube current is increased to peak level throughout the entire cardiac cycle, then projection data quality is improved, but radiation exposure increases
Solution Approach 1:
The tube current is modulated periodically according to the cardiac cycle phases. High tube current is applied only during diastole when the heart is relatively stationary and projection data is most valuable, while low tube current is applied during systole when motion artifacts would degrade image quality. This periodic modulation maintains projection data quality during critical phases while minimizing radiation exposure during less critical phases, resolving the contradiction between data quality and 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 reduces patient x-ray dose by up to 37% by selectively exposing only necessary detector rows during cardiac studies, effectively managing radiation exposure and improving image reconstruction accuracy.
Implementation Method 1
The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object
Implementation Method 2
obtain EKG gating information from an object and obtain attenuation measurements from the object
Data Source
AI summary
In one embodiment, a method is provided for performing computed tomography (CT) imaging. The method includes obtaining EKG gating information from an object and obtaining attenuation measurements from the object utilizing a detector that is rotated in a scan plane around the object. The method further includes performing a first reconstruction based on a first portion of the attenuation measurements that are collected by a first region of the detector, where the first reconstruction is performed independent of the EKG gating information to obtain a first reconstruction data set. A second reconstruction is performed based on a second port of the attenuation measurements that are collected by a second region of the detector, where the second reconstruction is performed based on the EKG gating information to obtain a second reconstruction data set.