Deep Neural Network 3D CT Reconstruction from Sparse X-ray Projections

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Solution Overview

Problem

Current methods for reconstructing 3D computed tomography (CT) volumes from X-ray radiographs require numerous images, increasing radiation exposure, time, and cost, and existing approaches for generating 3D segmentation masks from limited X-ray images are either manual, semi-automatic, or rely on statistical shape models, which are inefficient.

Innovation Solution

A method using a trained deep neural network, specifically a deep image-to-image network within a conditional-generative adversarial network, to generate a sparse 3D volume from a small number of X-ray images, which is then decoded into a final reconstructed 3D CT volume and segmentation mask, reducing the need for extensive image data and improving automation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If many X-ray images are taken from various angles for CT reconstruction, then the quality and detail of the 3D CT volume is improved, but patient radiation exposure increases and acquisition time and cost increase

Engineering Contradiction:
Improve3D CT volume qualityVSAvoidpatient radiation exposure
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies partial action by using only a limited number of X-ray images (e.g., 3-7 images) instead of the many images required by conventional CT, achieving sufficient reconstruction quality for segmentation purposes while reducing radiation exposure. The deep learning model compensates for the limited data through learned priors from training on complete CT scans.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent introduces a deep learning model as an intermediary that transforms a sparse set of X-ray images into a reconstructed 3D volume. This intermediary learns the mapping from limited projections to complete volumetric data, enabling quality reconstruction without requiring numerous input images.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If many X-ray images are taken for CT reconstruction, then the accuracy of the 3D CT volume is improved, but acquisition time increases

Engineering Contradiction:
Improve3D CT volume accuracyVSAvoidacquisition time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The method uses a partial set of X-ray images (minimal subset) rather than complete angular sampling, reducing acquisition time while maintaining sufficient accuracy for anatomical segmentation through deep learning-based reconstruction.

Inventive Principle:
Principle #16Partial or excessive action

3Measurement precision

If manual or semi-automatic methods are used for generating 3D segmentation masks from limited X-ray images, then some level of accuracy can be achieved, but the process is inefficient and time-consuming

Engineering Contradiction:
Improvesegmentation mask accuracyVSAvoidsegmentation efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system applies self-service by using the reconstructed 3D volume to automatically generate segmentation masks through the deep learning model, eliminating the need for manual or semi-automatic segmentation processes. The model learns anatomical structures from training data and applies this knowledge to automatically segment the reconstructed volumes.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical segmentation processes with an automated deep learning-based system that processes the reconstructed 3D volume to generate segmentation masks, significantly improving efficiency while maintaining or improving accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If conventional tomographic reconstruction algorithms are used with limited X-ray images, then a sparse 3D volume can be generated, but the quality and completeness of the reconstructed volume is insufficient for clinical use

Engineering Contradiction:
Improvereconstruction speedVSAvoidreconstructed volume quality
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The deep learning model serves as an intermediary that enhances the sparse volume generated by conventional algorithms, transforming it into a complete, high-quality 3D CT volume suitable for clinical segmentation tasks.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The method changes the parameter of image completeness by using the deep learning model to fill in missing information and enhance the sparse reconstruction, transforming it from an incomplete representation to a clinically useful volumetric dataset.

Inventive Principle:
Principle #35Parameter changes

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 allows for the automated reconstruction of 3D CT volumes and segmentation masks from a minimal number of X-ray images, reducing patient radiation exposure, time, and costs while providing accurate anatomical reconstructions, enabling efficient pre-operative planning and surgery guidance.

Implementation Method 1

generating a final reconstructed 3D CT volume from the sparse 3D volume using a trained deep neural network

Methodology Applied
Scientific EffectDeep neural network processing:

Implementation Method 2

generating the sparse 3D volume from the first X-ray image and the second X-ray image using a tomographic reconstruction algorithm

Methodology Applied
Scientific EffectTomographic reconstruction: Tomography

Data Source

PatentEP3525171B1Method and system for 3D reconstruction of x-ray CT volume and segmentation mask from a few x-ray radiographs
Publication Date: 2020.12.02 SIEMENS HEALTHCARE GMBH
  • EP3525171B1 patent drawingFigure 1
  • EP3525171B1 patent drawingFigure 2~4
  • EP3525171B1 patent drawingFigure 5

AI summary

A method and apparatus for automated reconstruction of a 3D computed tomography (CT) volume from a small number of X-ray images is disclosed. A sparse 3D volume is generated from a small number of x-ray images using a tomographic reconstruction algorithm. A final reconstructed 3D CT volume is generated from the sparse 3D volume using a trained deep neural network. A 3D segmentation mask can also be generated from the sparse 3D volume using the trained deep neural network.