CT Image Reconstruction via Attenuation Correction

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Solution Overview

Problem

Computed tomography (CT) image reconstruction is hindered by radiation dose fluctuations during gantry rotation, leading to inconsistencies between projection images and resulting in poor imaging quality and potential false medical diagnoses.

Innovation Solution

A system and method for reconstructing CT images by simultaneously solving correction coefficients of projection images to minimize the difference between estimated and actual attenuation information, using a processor to construct an estimated attenuation information function and a cost function to measure this difference, thereby improving image quality without the need for high-precision devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a high-precision device (control system or reference ionization chamber) is introduced to correct radiation dose fluctuations, then the imaging quality improves, but the hardware cost increases

Engineering Contradiction:

Improveimaging qualityVSAvoidhardware cost

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/hardware-based correction system (reference ionization chamber and control system) with a computational approach. The processor performs calculations on the projection images to determine correction coefficients and reconstruct the CT image, substituting physical measurement devices with mathematical algorithms that run on standard computing hardware.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses the projection images themselves to generate the correction coefficients needed for their own correction. The processor analyzes the projection images, identifies inconsistencies caused by radiation dose fluctuations, and automatically computes the correction factors without requiring external reference measurements or additional sensing devices.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If projection images are corrected before reconstruction, then the imaging quality improves, but the method is unsuitable for scans with less than 360-degree gantry rotation

Engineering Contradiction:

Improveimaging qualityVSAvoidscan angle range applicability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic correction approach where the correction coefficients are determined as part of the reconstruction process itself, rather than applying a fixed correction before reconstruction. This allows the method to adapt to different scan geometries including partial-angle scans (less than 360 degrees), as the correction is optimized for the specific projection data available in each scan scenario.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If radiation dose is maintained uniform during gantry rotation, then the inconsistency between projection images is reduced, but the radiation dose delivery becomes less adaptable to patient anatomy variations

Engineering Contradiction:

Improveprojection image consistencyVSAvoidradiation dose adaptability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent implements a feedback mechanism where the processor analyzes the actual projection images to detect inconsistencies caused by radiation dose fluctuations, then uses this information to compute correction coefficients that compensate for the variations. This feedback loop allows the system to maintain adaptability in radiation delivery while achieving consistency in the final image through computational correction.

Inventive Principle:

Principle #23Feedback

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 quality of reconstructed CT images by reducing radiation dose inconsistencies across gantry angles, applicable to various scan scenarios, including those with less than 360-degree rotation, without the requirement for expensive high-precision equipment.

Implementation Method 1

determine attenuation information of the plurality of projection images... difference between estimated attenuation information of the plurality of projection images and the attenuation information of the plurality of projection images

Methodology Applied

Scientific EffectX-ray attenuation: Absorption (EM radiation)

Data Source

PatentUS11080896B2Systems and methods for computed tomography image reconstruction

Publication Date: 2021.08.03 SHANGHAI UNITED IMAGING HEALTHCARE

AI summary

The present disclosure provides a method for computed tomography (CT) image reconstruction. The method may include obtaining a plurality of projection images of a subject. The plurality of projection images may be generated according to scan data acquired by a CT scanner at a plurality of gantry angles, each of the plurality of projection images corresponding to one of the plurality of gantry angles. The method may also include determining attenuation information of the plurality of projection images. The method may further include reconstructing a CT image of the subject by simultaneously solving correction coefficients of the plurality of projection images such that a difference between estimated attenuation information of the plurality of projection images and the attenuation information of the plurality of projection images is minimized.