Diaphragm Edge Detection in X-Ray Images Using Structural Filtering

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Solution Overview

Problem

Existing computer-assisted detection methods for diaphragm edges in x-ray images are unreliable under adverse conditions, particularly when large implants are present or when diaphragm contrast is similar to the patient contrast, leading to incorrect or missed edge recognition.

Innovation Solution

The method involves providing the computer with information about the inner structure of the diaphragm, such as regular geometric shapes, and using derivative values and weighting factors to detect diaphragm edges by identifying edges that form specific angles and maintaining a minimum separation, thereby enhancing the accuracy of edge detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If computer-assisted detection methods are used to automatically detect diaphragm edges, then productivity is improved, but reliability deteriorates under disadvantageous conditions such as large implants or low contrast

Engineering Contradiction:
Improveautomatic edge detection speedVSAvoidedge detection accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The detection process is segmented into multiple stages: first detecting all potential image edges, then filtering these edges based on structural criteria (forming rectangles with specific angles and parallel sides), and finally identifying diaphragm edges from the filtered set. This multi-stage segmentation allows automatic detection to maintain high productivity while improving reliability through progressive filtering.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary filtering mechanism that uses known diaphragm structural properties (rectangular shape, 90-degree angles, parallel opposite sides) as intermediate criteria to bridge the gap between automatic edge detection and reliable diaphragm edge identification. This intermediary layer eliminates false detections from implants or other structures while preserving true diaphragm edges.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If manual input methods are used to enter diaphragm edge positions, then reliability is improved, but productivity deteriorates due to slow and laborious operation

Engineering Contradiction:
Improveedge position accuracyVSAvoidedge detection speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system performs self-service by automatically detecting and identifying diaphragm edges using computational algorithms that analyze image data and apply structural filtering criteria. This eliminates the need for manual user input while maintaining high detection accuracy, thereby resolving the contradiction between reliability and productivity.

Inventive Principle:
Principle #25Self-service

3Device complexity

If simple edge detection algorithms are used, then device complexity is reduced, but measurement precision deteriorates when diaphragm contrast differs little from patient contrast

Engineering Contradiction:
Improvedetection algorithm simplicityVSAvoiddiaphragm edge detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by first detecting all potential edges in the image, then using preliminary filtering based on known diaphragm structural properties (rectangular geometry, angle relationships, parallel sides) to identify which edges belong to the diaphragm. This preliminary structuring of the detection process improves measurement precision without requiring overly complex algorithms.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes detection parameters dynamically by adjusting the stringency of structural criteria application based on image characteristics. When contrast is low, the algorithm relies more heavily on geometric structural parameters (angles, parallelism, rectangle formation) rather than purely on intensity-based edge detection, thereby maintaining precision without excessive complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS7499575B2Computer-assisted detection method for diaphragm edges caused in an image by a diaphragm
Publication Date: 2009.03.03 SIEMENS HEALTHINEERS AG
  • US7499575B2 patent drawing
  • US7499575B2 patent drawing
  • US7499575B2 patent drawing

AI summary

In a computer-assisted method for detecting diaphragm edges caused in an image by a diaphragm, the image and information about an inner structure of the diaphragm are provided to a computer. The computer first detects all image edges that are present in the image. Using the information about the inner structure of the diaphragm, it then determines the diaphragm edges from among the detected image edges.