Basis Material Transformation in X-ray CT Image Processing

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Solution Overview

Problem

X-ray CT devices using photon counting detectors require extensive preprocessing and storage for transformation parameters, leading to increased calculation time and storage needs, especially when generating multiple types of basis material images.

Innovation Solution

An image processing device that calculates physical amounts of basis materials using projection data and generates images, allowing for efficient calculation of multiple basis materials without increasing calculation time, by employing a first basis material transformation unit and a second basis material transformation unit based on different energy distributions and image processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If transformation parameters are provided for respective X-ray irradiation conditions and combinations of basis materials, then the accuracy of physical amount calculation is improved, but the storage capacity and preprocessing time are increased

Engineering Contradiction:

Improveaccuracy of physical amount calculationVSAvoidstorage capacity for transformation parameters

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent uses a single set of transformation parameters that can be applied across multiple X-ray irradiation conditions and basis material combinations. The image generation unit generates different types of images (projection images, reconstructed images, basis material distribution images) using the same transformation parameters, eliminating the need to store separate parameters for each condition and combination.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts the transformation parameter determination from the per-condition processing and performs it once globally. The determination unit determines transformation parameters based on the X-ray spectrum without needing to repeat this for each irradiation condition or basis material combination, thereby reducing storage requirements.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

Engineering Contradiction:

Improveaccuracy of physical amount calculationVSAvoidpreprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The determination unit determines the transformation parameters in advance based on the X-ray spectrum before actual image generation. This preliminary determination is performed once and the parameters are reused for generating multiple types of images under different conditions, avoiding repeated preprocessing time.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple types of basis materials are set to generate respective images, then the versatility of the system is improved, but the number of processes and storage capacity are increased

Engineering Contradiction:

Improveability to generate multiple basis material imagesVSAvoidnumber of processes

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The image generation unit is designed to generate multiple types of images (projection images, reconstructed images, basis material distribution images) using a single set of transformation parameters. This universal approach allows the system to handle multiple basis materials without increasing process complexity, as the same transformation parameters apply across all image types and basis material combinations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables the calculation of physical amounts of multiple basis materials without prolonging calculation time and facilitates the acquisition of desired images, reducing the need for extensive preprocessing and storage of transformation parameters.

Implementation Method 1

X-ray CT device is a device that calculates X-ray absorption coefficients (linear attenuation coefficient) from projection data which is an X-ray transmission image of a subject under test photographed from a plurality of directions

Methodology Applied

Scientific EffectX-ray transmission: X-Ray

Implementation Method 2

X-ray absorption coefficients (linear attenuation coefficient)

Methodology Applied

Scientific EffectX-ray absorption: Absorption (EM radiation)

Implementation Method 3

an X-ray detector of the photon counting type, which measures the number of X-ray photons

Methodology Applied

Scientific EffectPhoton counting:

Data Source

PatentUS11058384B2Image processing device, X-ray CT device, and image processing method

Publication Date: 2021.07.13 HITACHI LTD

AI summary

This is directed to calculating physical amounts of a plurality of types of basis materials without having to increase a calculation time.An image processing device is provided which includes a first basis material transformation unit that calculates each of physical amounts of two or more basis materials included in a first basis material group based on two or more types of projection data different in energy distribution, an image generation unit that generates a plurality of images, each of which is at least one of a projection image and a reconstructed image of an object, from physical amounts of two or more basis materials included in the first basis material group, and a second basis material transformation unit that calculates a physical amount of a basis material included in a second basis material group which is different from the first basis material group based on the plurality of images.