Spatially Resolved WED Detection in Head-Feet Direction

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Solution Overview

Problem

Current methods for determining the equivalent diameter of a human examination subject in X-ray images are inadequately resolved in the head-to-toe direction and fail to accurately account for the patient table's position, leading to inaccurate X-ray dose calculations and unnecessary alarms during three-dimensional scans.

Innovation Solution

An evaluation method that removes the arms of the examination subject from X-ray images and corrects for the patient table's absorption, determining the equivalent diameter in a plane orthogonal to the head-to-toe direction using Hounsfield units, with the option to store and retrieve images from a cloud for automated processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the equivalent diameter is determined uniformly for selected two-dimensional areas in the prior art method, then the calculation process is simplified, but the measurement precision in the head-toe direction deteriorates

Engineering Contradiction:
Improvecalculation process complexityVSAvoidequivalent diameter resolution in head-toe direction
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the examination subject into multiple cross-sectional areas at different positions in the head-toe direction. Instead of determining a single uniform equivalent diameter, the method calculates separate equivalent diameters for each cross-sectional area, thereby improving measurement precision along the head-toe direction while maintaining manageable calculation complexity through systematic segmentation.

Inventive Principle:
Principle #1Segmentation

2Loss of information

If the arms are included in the X-ray image for equivalent diameter determination, then the complete anatomical structure is captured, but the measurement precision deteriorates due to arm interference

Engineering Contradiction:
Improveanatomical structure completenessVSAvoidequivalent diameter accuracy
Core Design Contradiction:
Loss of informationVSMeasurement precision

Solution Approach 1:

The patent extracts and removes the arms from the X-ray image before determining the equivalent diameter. By eliminating the arms as interfering elements, the method improves measurement precision for the main body of the examination subject. The arms are specifically identified and excluded from the calculation area to prevent them from distorting the equivalent diameter measurement.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If the patient table absorption is not corrected for, then the evaluation process is simpler, but the measurement precision deteriorates due to table interference

Engineering Contradiction:
Improveevaluation process complexityVSAvoidequivalent diameter accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary correction of the X-ray image by removing the absorption effect of the patient table before equivalent diameter determination. This preliminary action eliminates a source of measurement error, ensuring that the equivalent diameter is calculated based only on the examination subject. The correction is applied in advance to prevent table interference from affecting the measurement precision.

Inventive Principle:
Principle #10Preliminary action

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 method provides a more accurate and manufacturer-independent determination of the equivalent diameter, reducing errors and unnecessary alarms by accounting for the patient table's position, and enabling efficient conversion to size-specific dose estimates for improved X-ray exposure control.

Implementation Method 1

X-ray images of a human examination subject recorded by means of an X-ray system

Methodology Applied
Scientific EffectX-ray absorption: Absorption (EM radiation)

Implementation Method 2

the diameter of the examination object related to water describes the total attenuation of X-rays by the examination object normalized to the attenuation of water

Methodology Applied
Scientific EffectX-ray attenuation: Absorption (EM radiation)

Implementation Method 3

An integration then takes place between the limits via the Hounsfield units of the respective x-ray image

Methodology Applied
Scientific EffectHounsfield units:

Data Source

PatentEP3311744B1Spatially resolved wed detection in head-foot direction
Publication Date: 2020.02.26 SIEMENS HEALTHCARE GMBH
  • EP3311744B1 patent drawingFigure 1~2
  • EP3311744B1 patent drawingFigure 3~4
  • EP3311744B1 patent drawingFigure 5~6

AI summary

X-ray images (B) of a human subject (6), acquired using an X-ray system (1), are spatially resolved in several dimensions. Each dimension extends in the head-to-toe direction of the subject (6). In the X-ray images (B), the respective body region is identified in equidistant steps in the head-to-toe direction, and based on this, the equivalent diameter (WED) of the subject (6) in relation to water is determined in a plane orthogonal to the head-to-toe direction. The equivalent diameters (WED) determined for each position (z) are stored, assigned to the X-ray images (B) and the respective position (z) in the head-to-toe direction.