Self-Calibrating X-Ray Scanner Using Radiopaque Markers

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Solution Overview

Problem

Mobile X-ray imaging scanners face challenges in accurately determining the geometric calibration of the x-ray source and detector, which is crucial for high-quality 3D volume imaging due to the lack of mechanically fixed geometry, leading to image artifacts and reduced spatial resolution.

Innovation Solution

A mobile radiography apparatus with radio-opaque markers positioned along the radiation path from the x-ray sources to the digital radiographic detector, where a processor calculates the detector's position relative to the x-ray sources based on marker positions in captured projection images, enabling accurate geometric calibration and reconstruction of 3D images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mobile radiography apparatus is used to image bed-ridden patients, then patient accessibility is improved, but geometric calibration accuracy deteriorates

Engineering Contradiction:

Improvepatient accessibilityVSAvoidgeometric calibration accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent introduces radiopaque markers as intermediary objects that serve as reference points for calibration. These markers are positioned at known locations and appear in the X-ray images, enabling the system to calculate the detector's position and orientation relative to the X-ray source without requiring direct mechanical coupling between the two components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical coupling system (which physically links source and detector) with an image-based calibration system using radiopaque markers. Instead of relying on mechanical precision, the system uses computational methods to determine geometric relationships from marker positions in captured images.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If mechanically uncoupled detector is used, then mobility and patient accessibility are improved, but source-detector geometry determination accuracy deteriorates

Engineering Contradiction:

ImprovemobilityVSAvoidsource-detector geometry determination

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent performs calibration before actual patient imaging by capturing images of radiopaque markers at multiple known positions. This preliminary calibration establishes the geometric relationship between source and detector, which is then used for accurate 3D reconstruction during patient imaging without requiring repeated calibration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent transitions from 2D planar imaging to 3D volumetric reconstruction by incorporating depth information through multiple projection images at different angles. The radiopaque markers provide reference points that enable calculation of three-dimensional spatial relationships, allowing accurate geometry determination even with mobile, uncoupled components.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Loss of time

If limited angular scanning is used, then scan time and mobility are improved, but in-depth resolution deteriorates

Engineering Contradiction:

Improvescan timeVSAvoidin-depth resolution

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The patent uses the detected positions of radiopaque markers in multiple projection images to feedback-calculate the detector's position and orientation at each angle. This feedback mechanism allows the system to compensate for the limited angular range by accurately tracking geometric relationships throughout the scan, improving reconstruction quality despite the constrained scanning angle.

Inventive Principle:

Principle #23Feedback

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 solution allows for more accurate source/detector calibration in mobile radiography systems, improving the quality of 3D volume imaging by reducing artifacts and enhancing spatial resolution, even in environments where mechanical linkage is not feasible.

Implementation Method 1

A mobile radiography apparatus with radio-opaque markers positioned along the radiation path from the x-ray sources to the digital radiographic detector

Methodology Applied

Scientific EffectX-ray absorption: Absorption (EM radiation)

Data Source

PatentUS11432789B2Self-calibrating technique for x-ray imaging scanners

Publication Date: 2022.09.06 CARESTREAM HEALTH INC

AI summary

A mobile radiography apparatus includes radiopaque markers disposed in a radiation path that extends from an x-ray source to a digital radiographic detector, which detector is mechanically uncoupled from the x-ray source or x-ray sources. A processing system calculates a position of the detector relative to the x-ray source or x-ray sources according to identified marker positions in acquired x-ray projection images, and reconstructs a volume image according to the acquired x-ray projection images.