Truncation Change Detection in Cone Beam CT

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Solution Overview

Problem

Cone beam computed tomography (CBCT) systems face challenges in accurately reconstructing examination objects due to truncation issues, where parts of the object are outside the main reconstruction volume, leading to errors in Hounsfield units and contrast distribution, particularly when the truncation changes between measurement processes, affecting image-based dosimetry in applications like selective internal beam therapy.

Innovation Solution

A method is developed to identify and compensate for changes in truncation between first and second projection photographs by correlating datasets using a control facility, which receives and processes sensor data to establish predefined change criteria, allowing for the correction of truncation changes without requiring extensive model-dependent adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If cone beam computed tomography is used for quantitative measurements, then imaging speed and efficiency are improved, but measurement precision deteriorates due to truncation errors and unreliable Hounsfield units

Engineering Contradiction:

Improveimaging speedVSAvoidHounsfield unit accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system performs preliminary detection of truncation changes between mask and full images before quantitative analysis. By identifying truncation artifacts early in the processing workflow, the system can flag affected regions and prevent erroneous quantitative measurements, thus maintaining measurement precision while preserving the efficiency of CBCT imaging

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary detection mechanism that analyzes projection photographs for truncation artifacts. This intermediary step acts as a mediator between the CBCT imaging process and quantitative measurement, allowing the system to maintain high imaging speed while improving measurement precision by identifying and correcting truncation-related errors

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If truncation is present in projection photographs, then the reconstruction process becomes more complex, but the reliability of contrast distribution measurement deteriorates

Engineering Contradiction:

Improvereconstruction complexityVSAvoidcontrast distribution accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the detection of truncation changes informs subsequent processing steps. When truncation artifacts are detected, the system provides feedback to adjust the quantitative analysis process, such as excluding affected regions or applying corrections, thereby improving contrast distribution measurement reliability

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 approach enables more robust and sensitive identification and correction of truncation changes, improving the accuracy of Hounsfield unit measurements and contrast distribution, reducing errors in image-based dosimetry and enhancing the reliability of CBCT reconstructions.

Implementation Method 1

X-ray radiation is emitted by an X-ray source onto the examination object

Methodology Applied

Scientific EffectX-ray radiation: X-Ray

Implementation Method 2

Located opposite the X-ray source is a flat panel detector that detects the emitted X-rays

Methodology Applied

Scientific EffectX-ray detection: Photoelectric Effect

Data Source

PatentUS20240096089A1Method for identifying a change in truncation, control facility, CT apparatus, computer program and electronically readable data carrier

Publication Date: 2024.03.21 SIEMENS HEALTHINEERS AG

AI summary

The invention relates to a method for identifying a change in truncation of an examination object between first projection photographs of the examination object generated by a CT apparatus, and second projection photographs of the examination object generated by the CT apparatus, comprising the following steps to be carried out by a control facility. Receiving a first dataset, comprising the first projection photographs of the examination object; receiving a second dataset, comprising the second projection photographs of the examination object; correlating the first dataset with the second dataset; establishing the change in truncation of the examination object between the first projection photographs and the second projection photographs when satisfaction of at least one predefined change criterion between the datasets is captured; and outputting a predetermined output signal when the change in truncation between the first projection photographs and the second projection photographs is established.