CT Shape Feature Extraction for Security Inspection False Alarm Reduction

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Solution Overview

Problem

Current security inspection methods using Dual Energy Computed Tomography (DECT) struggle with false alarms due to overlapping perspective structures and metal interference, limiting the effective detection of explosives or suspicious objects.

Innovation Solution

The method involves extracting shape features from 3D volume data in a CT system by calculating depth projection images and symmetry metrics, generating a shape feature parameter, and combining it with physical property information to improve detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If material property-based detection is used in DECT, then detection capability for explosives is improved, but false alarm rate increases due to artifacts, metal interference, and non-suspicious objects

Engineering Contradiction:
Improvedetection accuracyVSAvoidfalse alarm rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The detection process is segmented into two independent stages: shape feature extraction (using symmetry metrics and depth projection) and material property analysis. This segmentation allows shape-based pre-screening to filter out false alarms before material property analysis, resolving the contradiction by separating the functions that cause interference from those that detect explosives

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from 2D DR image analysis to 3D CT volume analysis by computing depth projection images and symmetry metrics in three-dimensional space. This dimensional change enables the system to distinguish objects based on their 3D shape characteristics, adding a new detection dimension that reduces false alarms while maintaining detection accuracy

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If 3D volume data processing is performed, then shape feature extraction accuracy is improved, but computational complexity increases

Engineering Contradiction:
Improveshape feature accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts only the essential shape features (symmetry metrics and depth projection images) from the 3D volume data, rather than processing the entire 3D dataset. By taking out and analyzing only the critical geometric characteristics, the system achieves accurate shape feature extraction while significantly reducing computational complexity compared to full 3D analysis

Inventive Principle:
Principle #2Taking out (Extraction)

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 reduces the false alarm rate by utilizing shape features to differentiate between suspicious and non-suspicious objects, enhancing the detection of explosives and improving the overall accuracy of security inspections.

Implementation Method 1

acquiring slice data of luggage under inspection with the CT system

Methodology Applied
Scientific EffectX-Ray: X-Ray

Implementation Method 2

generating, from the slice data, 3-dimensional (3D) volume data of at least one object in the luggage

Methodology Applied
Scientific EffectTomography: Tomography

Data Source

PatentUS10102641B2Methods for extracting shape feature, inspection methods and apparatuses
Publication Date: 2018.10.16 NUCTECH CO LTD
  • US10102641B2 patent drawing
  • US10102641B2 patent drawing
  • US10102641B2 patent drawing

AI summary

Methods for extracting a shape feature of an object and security inspection methods and apparatuses. Use is made of CT's capability of obtaining a 3D structure. The shape of an object in an inspected luggage is used as a feature of a suspicious object in combination with a material property of the object. For example, a false alarm rate in detection of suspicious explosives may be reduced.