4 research outputs found
Development and validation of two novel x-ray filters in computed tomography with focus on fluence modulation for region-of-interest imaging
Die Röntgen-Computertomographie (CT) hat sich zu einem zentralen Element der klinischen Bildgebung entwickelt. Sie liefert Schichtbilder, die sich durch eine hohe zeitliche und räumliche Auflösung bei sehr kurzen Aufnahmezeiten auszeichnen. Allerdings verwendet die CT zur Bildaufnahme ionisierende Röntgenstrahlung, die ein potenzielles Gesundheitsrisiko für den Patienten darstellt. Über die Jahre wurden viele Maßnahmen ergriffen, um die Strahlendosis zu reduzieren. Ein Ansatz ist die dynamische Vorfilterung des Röntgenstrahls, um die Abschwächung der Röntgenstrahlung durch den Patienten, die über die Projektionen und die Fächerstrahlbreite variiert, zu kompensieren. Bowtie-Filter moderner CT Systeme nach dem Stand der Technik sind jedoch statische Vollkörper und können sich nicht an die individuelle Patientenschwächung anpassen. Eine Lösung für patienten- und aufgabenspezifische CT Bildgebung ist die Modulation des Fluenzbereichs (FFM) unter Verwendung eines dynamischen Strahlabschwächers (DBA). DBAs ermöglichen es, die Röntgenfluenz während der Datenaufnahme anzupassen. Existierende DBA-Konzepte zeigen jedoch grundsätzliche Schwachstellen (z.B. zu groß oder zu langsam), die eine Realisierung in klinischen CT Systemen ausschließen. In dieser Thesis wurden zwei grundlegend neue DBA-Konzepte entwickelt, um die mangelnde Flexibilität derzeitiger Bowtie-Filter und die Einschränkungen bisheriger DBA-Ansätze zu überwinden. Der lamellenbasierte DBA (sbDBA) besteht aus einer Anordnung von stark röntgenabsorbierenden Lamellen. Je nach Verkippung des sbDBA verändert sich die Transmission durch den sbDBA – vergleichbar mit Jalousien. Auch der artverwandte, z-ausgerichtete sbDBA (z-sbDBA) besitzt Absorptionslamellen zur FFM, verwendet jedoch eine überarbeitete Strukturierung und eine einfachere Mechanik. Ausgehend von einfachen Skizzen wurden reale Prototypen des sbDBA und des z-sbDBA gebaut und in ein klinisches CT System integriert. Im ersten Teil dieser Arbeit wurden das modifizierte CT System und Monte-Carlo Simulationen, die dieses CT System nachbilden, verwendet, um die DBAs zu untersuchen. In Versuchsmessungen konnten beide DBAs verschiedene Transmissionprofile erzeugen und somit FFM – die Hauptfunktion eines DBA – realisieren. Während der sbDBA auch die Verschiebung der Maximaltransmission erlaubte, wurden mit dem z-sbDBA geeignetere Verläufe der Transmissionsprofile erzielt. Ein Vergleich spektraler Abhängigkeit der Transmission und DBA-induzierter Streustrahlung zeigte bemerkenswerte Vorteile gegenüber herkömmlichen Bowtie-Filtern. Obwohl einzelne Ringartefakte in ersten Bildrekonstruktionen Herausforderung hinsichtlich der mechanischen Stabilität der DBAs aufzeigten, war die Bildqualität insgesamt vielversprechend. Im zweiten Teil wurde das Potenzial für Zielvolumen (ROI) Bildgebung untersucht, bei der nur ein bestimmter Bereich mit hoher Qualität dargestellt und im umliegenden Gewebe die Dosis minimiert wird. Zunächst wurde hierzu ein Optimierungskriterium entwickelt, mit dem die Kippbewegungen der DBAs hinsichtlich eines diagnostischen Ziels optimiert werden. Dabei soll die Patientendosis minimiert und die Bildqualität innerhalb der ROI maximiert werden. Die erzeugten DBA-Trajektorien passten die emittierte Röntgenfluenz an die Geometrie der ROI an. Anschließend wurden verschiedene FFM-Konfigurationen, einschließlich Röhrenstrommodulation und zweier Bowtie-Filter, mit den DBAs bezüglich ihrer Dosiseffizienz bei ROI-Bildgebung verglichen. Es zeigte sich, dass die DBAs die Röntgenstrahlung effizienter einsetzten als Bowtie-Filter moderner CT Systeme: Bei Verwendung der DBAs konnten die ROIs bei gleichbleibender Bildqualität mit bis zu 30 % (z-sbDBA) bzw. 60 % (sbDBA) weniger Dosis im Vergleich zu einem typischen Bowtie-Filter dargestellt werden. In dieser Arbeit wurden zwei neuartige DBA-Konzepte entwickelt und in ein klinisches CT System installiert. Diese DBAs wurden hinsichtlich FFM erfolgreich validiert und zeigten bei ROI-Bildgebung erhebliches Dosiseinsparpotential im Vergleich zu heutiger FFM-Technik. Die vielversprechenden Ergebnisse bilden eine Grundlage für zukünftige Dosisreduktionen und ebnen den Weg für ROI-Bildgebung in der CT Diagnostik.X-ray computed tomography (CT) imaging has become a workhorse of today’s clinical imaging. It provides cross-sectional diagnostic images featuring high temporal and spatial resolution at very short acquisition times. However, CT images are acquired using x-rays, which bears a potential health detriment to the patient due to ionization radiation. Over the decades, many efforts have been undertaken to reduce the radiation burden. One approach is to employ dynamic pre-filtration of the x-ray beam to compensate for the patient’s x-ray attenuation that changes across the projections and the fan beam angle. State-of-the-art bowtie filters in clinical CT systems, however, are static and therefore cannot adapt to patient attenuation individually. A solution for patient- and task-specific CT imaging is fluence field modulation (FFM) by employing a dynamic beam attenuator (DBA). DBAs are capable of adapting the x-ray fluence during the data acquisition. Existing DBA concepts, however, suffer from inherent limitations (e.g., too large or too slow) that preclude an implementation in clinical CT systems. In this thesis, two fundamentally new DBA concepts were developed to overcome the lack of flexibility of present bowtie filters and the pitfalls of previous DBA approaches. The sheet-based DBA (sbDBA) was composed of an array of highly x-ray attenuating sheets. Depending on the way the sbDBA was tilted, the transmission through the sbDBA changed – comparable to Persian blinds. Likewise, the z-aligned sbDBA (z-sbDBA) employed attenuation sheets for FFM, although it used a revised structuring and simplified mechanics. Starting from simple sketches, physical prototypes of the sbDBA and the z-sbDBA were built and integrated into a clinical CT system. In the first part of this thesis, the DBAs were investigated using the modified CT system and Monte Carlo simulations mimicking this CT system. In experimental measurements, both DBAs were able to realize a wide range of transmission profiles and therefore successfully demonstrated their feasibility of FFM — the key function of a DBA. While the sbDBA allowed to shape the transmission profiles more flexibly by shifting the peak transmission also laterally, the z-sbDBA realized more suitable shapes. A comparison regarding the spectral dependency of the transmission and attenuator-induced scatter revealed remarkable advantages over conventional bowtie filters. Although ring artifacts in first-time image reconstructions unveiled challenges concerning the mechanical reliability of the DBAs, the overall image quality was promising. In the second part, the potential for region-of-interest (ROI) imaging, where only a specific region is imaged at high quality while the dose is minimized in surrounding tissue, was explored. In the first step, an optimization objective was developed to optimize the angular movements of the DBA regarding a given imaging task. The optimization aims at minimizing the patient dose and maximizing the image quality inside the ROI. The optimized DBA movements reasonably adapted the emitted x-ray fluence to the geometry of the ROI. In the second step, different FFM configurations, including tube current modulation and different bowtie filters, were compared with the DBAs regarding their dose efficiency in ROI imaging. The DBAs were shown to exploit the x-ray radiation more efficiently than the bowtie filters of modern CT systems: using the DBAs, the ROIs were imaged with up to 30 % (z-sbDBA) or 60 % (sbDBA) less radiation dose compared to a typical bowtie filter while maintaining the image quality in the ROI. In conclusion, two novel DBA concepts were developed and installed into a clinical CT system. These DBAs were successfully validated regarding FFM and demonstrated a remarkable dose saving potential in ROI imaging compared to state-of-the-art FFM technology. The promising results give rise for future radiation dose reductions and pave the way to ROI imaging in diagnostic CT
Human Practice. Digital Ecologies. Our Future. : 14. Internationale Tagung Wirtschaftsinformatik (WI 2019) : Tagungsband
Erschienen bei: universi - Universitätsverlag Siegen. - ISBN: 978-3-96182-063-4Aus dem Inhalt:
Track 1: Produktion & Cyber-Physische Systeme
Requirements and a Meta Model for Exchanging Additive Manufacturing Capacities
Service Systems, Smart Service Systems and Cyber- Physical Systems—What’s the difference? Towards a Unified Terminology
Developing an Industrial IoT Platform – Trade-off between Horizontal and Vertical Approaches
Machine Learning und Complex Event Processing: Effiziente Echtzeitauswertung am Beispiel Smart Factory
Sensor retrofit for a coffee machine as condition monitoring and predictive maintenance use case
Stakeholder-Analyse zum Einsatz IIoT-basierter Frischeinformationen in der Lebensmittelindustrie
Towards a Framework for Predictive Maintenance Strategies in Mechanical Engineering - A Method-Oriented Literature Analysis
Development of a matching platform for the requirement-oriented selection of cyber physical systems for SMEs
Track 2: Logistic Analytics
An Empirical Study of Customers’ Behavioral Intention to Use Ridepooling Services – An Extension of the Technology Acceptance Model
Modeling Delay Propagation and Transmission in Railway Networks
What is the impact of company specific adjustments on the acceptance and diffusion of logistic standards?
Robust Route Planning in Intermodal Urban Traffic
Track 3: Unternehmensmodellierung & Informationssystemgestaltung (Enterprise Modelling & Information Systems Design)
Work System Modeling Method with Different Levels of Specificity and Rigor for Different Stakeholder Purposes
Resolving Inconsistencies in Declarative Process Models based on Culpability Measurement
Strategic Analysis in the Realm of Enterprise Modeling – On the Example of Blockchain-Based Initiatives for the Electricity Sector
Zwischenbetriebliche Integration in der Möbelbranche: Konfigurationen und Einflussfaktoren
Novices’ Quality Perceptions and the Acceptance of Process Modeling Grammars
Entwicklung einer Definition für Social Business Objects (SBO) zur Modellierung von Unternehmensinformationen
Designing a Reference Model for Digital Product Configurators
Terminology for Evolving Design Artifacts
Business Role-Object Specification: A Language for Behavior-aware Structural Modeling of Business Objects
Generating Smart Glasses-based Information Systems with BPMN4SGA: A BPMN Extension for Smart Glasses Applications
Using Blockchain in Peer-to-Peer Carsharing to Build Trust in the Sharing Economy
Testing in Big Data: An Architecture Pattern for a Development Environment for Innovative, Integrated and Robust Applications
Track 4: Lern- und Wissensmanagement (e-Learning and Knowledge Management)
eGovernment Competences revisited – A Literature Review on necessary Competences in a Digitalized Public Sector
Say Hello to Your New Automated Tutor – A Structured Literature Review on Pedagogical Conversational Agents
Teaching the Digital Transformation of Business Processes: Design of a Simulation Game for Information Systems Education
Conceptualizing Immersion for Individual Learning in Virtual Reality
Designing a Flipped Classroom Course – a Process Model
The Influence of Risk-Taking on Knowledge Exchange and Combination
Gamified Feedback durch Avatare im Mobile Learning
Alexa, Can You Help Me Solve That Problem? - Understanding the Value of Smart Personal Assistants as Tutors for Complex Problem Tasks
Track 5: Data Science & Business Analytics
Matching with Bundle Preferences: Tradeoff between Fairness and Truthfulness
Applied image recognition: guidelines for using deep learning models in practice
Yield Prognosis for the Agrarian Management of Vineyards using Deep Learning for Object Counting
Reading Between the Lines of Qualitative Data – How to Detect Hidden Structure Based on Codes
Online Auctions with Dual-Threshold Algorithms: An Experimental Study and Practical Evaluation
Design Features of Non-Financial Reward Programs for Online Reviews: Evaluation based on Google Maps Data
Topic Embeddings – A New Approach to Classify Very Short Documents Based on Predefined Topics
Leveraging Unstructured Image Data for Product Quality Improvement
Decision Support for Real Estate Investors: Improving Real Estate Valuation with 3D City Models and Points of Interest
Knowledge Discovery from CVs: A Topic Modeling Procedure
Online Product Descriptions – Boost for your Sales?
Entscheidungsunterstützung durch historienbasierte Dienstreihenfolgeplanung mit Pattern
A Semi-Automated Approach for Generating Online Review Templates
Machine Learning goes Measure Management: Leveraging Anomaly Detection and Parts Search to Improve Product-Cost Optimization
Bedeutung von Predictive Analytics für den theoretischen Erkenntnisgewinn in der IS-Forschung
Track 6: Digitale Transformation und Dienstleistungen
Heuristic Theorizing in Software Development: Deriving Design Principles for Smart Glasses-based Systems
Mirroring E-service for Brick and Mortar Retail: An Assessment and Survey
Taxonomy of Digital Platforms: A Platform Architecture Perspective
Value of Star Players in the Digital Age
Local Shopping Platforms – Harnessing Locational Advantages for the Digital Transformation of Local Retail Outlets: A Content Analysis
A Socio-Technical Approach to Manage Analytics-as-a-Service – Results of an Action Design Research Project
Characterizing Approaches to Digital Transformation: Development of a Taxonomy of Digital Units
Expectations vs. Reality – Benefits of Smart Services in the Field of Tension between Industry and Science
Innovation Networks and Digital Innovation: How Organizations Use Innovation Networks in a Digitized Environment
Characterising Social Reading Platforms— A Taxonomy-Based Approach to Structure the Field
Less Complex than Expected – What Really Drives IT Consulting Value
Modularity Canvas – A Framework for Visualizing Potentials of Service Modularity
Towards a Conceptualization of Capabilities for Innovating Business Models in the Industrial Internet of Things
A Taxonomy of Barriers to Digital Transformation
Ambidexterity in Service Innovation Research: A Systematic Literature Review
Design and success factors of an online solution for cross-pillar pension information
Track 7: IT-Management und -Strategie
A Frugal Support Structure for New Software Implementations in SMEs
How to Structure a Company-wide Adoption of Big Data Analytics
The Changing Roles of Innovation Actors and Organizational Antecedents in the Digital Age
Bewertung des Kundennutzens von Chatbots für den Einsatz im Servicedesk
Understanding the Benefits of Agile Software Development in Regulated Environments
Are Employees Following the Rules? On the Effectiveness of IT Consumerization Policies
Agile and Attached: The Impact of Agile Practices on Agile Team Members’ Affective Organisational Commitment
The Complexity Trap – Limits of IT Flexibility for Supporting Organizational Agility in Decentralized Organizations
Platform Openness: A Systematic Literature Review and Avenues for Future Research
Competence, Fashion and the Case of Blockchain
The Digital Platform Otto.de: A Case Study of Growth, Complexity, and Generativity
Track 8: eHealth & alternde Gesellschaft
Security and Privacy of Personal Health Records in Cloud Computing Environments – An Experimental Exploration of the Impact of Storage Solutions and Data Breaches
Patientenintegration durch Pfadsysteme
Digitalisierung in der Stressprävention – eine qualitative Interviewstudie zu Nutzenpotenzialen
User Dynamics in Mental Health Forums – A Sentiment Analysis Perspective
Intent and the Use of Wearables in the Workplace – A Model Development
Understanding Patient Pathways in the Context of Integrated Health Care Services - Implications from a Scoping Review
Understanding the Habitual Use of Wearable Activity Trackers
On the Fit in Fitness Apps: Studying the Interaction of Motivational Affordances and Users’ Goal Orientations in Affecting the Benefits Gained
Gamification in Health Behavior Change Support Systems - A Synthesis of Unintended Side Effects
Investigating the Influence of Information Incongruity on Trust-Relations within Trilateral Healthcare Settings
Track 9: Krisen- und Kontinuitätsmanagement
Potentiale von IKT beim Ausfall kritischer Infrastrukturen: Erwartungen, Informationsgewinnung und Mediennutzung der Zivilbevölkerung in Deutschland
Fake News Perception in Germany: A Representative Study of People’s Attitudes and Approaches to Counteract Disinformation
Analyzing the Potential of Graphical Building Information for Fire Emergency Responses: Findings from a Controlled Experiment
Track 10: Human-Computer Interaction
Towards a Taxonomy of Platforms for Conversational Agent Design
Measuring Service Encounter Satisfaction with Customer Service Chatbots using Sentiment Analysis
Self-Tracking and Gamification: Analyzing the Interplay of Motivations, Usage and Motivation Fulfillment
Erfolgsfaktoren von Augmented-Reality-Applikationen: Analyse von Nutzerrezensionen mit dem Review-Mining-Verfahren
Designing Dynamic Decision Support for Electronic Requirements Negotiations
Who is Stressed by Using ICTs? A Qualitative Comparison Analysis with the Big Five Personality Traits to Understand Technostress
Walking the Middle Path: How Medium Trade-Off Exposure Leads to Higher Consumer Satisfaction in Recommender Agents
Theory-Based Affordances of Utilitarian, Hedonic and Dual-Purposed Technologies: A Literature Review
Eliciting Customer Preferences for Shopping Companion Apps: A Service Quality Approach
The Role of Early User Participation in Discovering Software – A Case Study from the Context of Smart Glasses
The Fluidity of the Self-Concept as a Framework to Explain the Motivation to Play Video Games
Heart over Heels? An Empirical Analysis of the Relationship between Emotions and Review Helpfulness for Experience and Credence Goods
Track 11: Information Security and Information Privacy
Unfolding Concerns about Augmented Reality Technologies: A Qualitative Analysis of User Perceptions
To (Psychologically) Own Data is to Protect Data: How Psychological Ownership Determines Protective Behavior in a Work and Private Context
Understanding Data Protection Regulations from a Data Management Perspective: A Capability-Based Approach to EU-GDPR
On the Difficulties of Incentivizing Online Privacy through Transparency: A Qualitative Survey of the German Health Insurance Market
What is Your Selfie Worth? A Field Study on Individuals’ Valuation of Personal Data
Justification of Mass Surveillance: A Quantitative Study
An Exploratory Study of Risk Perception for Data Disclosure to a Network of Firms
Track 12: Umweltinformatik und nachhaltiges Wirtschaften
Kommunikationsfäden im Nadelöhr – Fachliche Prozessmodellierung der Nachhaltigkeitskommunikation am Kapitalmarkt
Potentiale und Herausforderungen der Materialflusskostenrechnung
Computing Incentives for User-Based Relocation in Carsharing
Sustainability’s Coming Home: Preliminary Design Principles for the Sustainable Smart District
Substitution of hazardous chemical substances using Deep Learning and t-SNE
A Hierarchy of DSMLs in Support of Product Life-Cycle Assessment
A Survey of Smart Energy Services for Private Households
Door-to-Door Mobility Integrators as Keystone Organizations of Smart Ecosystems: Resources and Value Co-Creation – A Literature Review
Ein Entscheidungsunterstützungssystem zur ökonomischen Bewertung von Mieterstrom auf Basis der Clusteranalyse
Discovering Blockchain for Sustainable Product-Service Systems to enhance the Circular Economy
Digitale Rückverfolgbarkeit von Lebensmitteln: Eine verbraucherinformatische Studie
Umweltbewusstsein durch audiovisuelles Content Marketing? Eine experimentelle Untersuchung zur Konsumentenbewertung nachhaltiger Smartphones
Towards Predictive Energy Management in Information Systems: A Research Proposal
A Web Browser-Based Application for Processing and Analyzing Material Flow Models using the MFCA Methodology
Track 13: Digital Work - Social, mobile, smart
On Conversational Agents in Information Systems Research: Analyzing the Past to Guide Future Work
The Potential of Augmented Reality for Improving Occupational First Aid
Prevent a Vicious Circle! The Role of Organizational IT-Capability in Attracting IT-affine Applicants
Good, Bad, or Both? Conceptualization and Measurement of Ambivalent User Attitudes Towards AI
A Case Study on Cross-Hierarchical Communication in Digital Work Environments
‘Show Me Your People Skills’ - Employing CEO Branding for Corporate Reputation Management in Social Media
A Multiorganisational Study of the Drivers and Barriers of Enterprise Collaboration Systems-Enabled Change
The More the Merrier? The Effect of Size of Core Team Subgroups on Success of Open Source Projects
The Impact of Anthropomorphic and Functional Chatbot Design Features in Enterprise Collaboration Systems on User Acceptance
Digital Feedback for Digital Work? Affordances and Constraints of a Feedback App at InsurCorp
The Effect of Marker-less Augmented Reality on Task and Learning Performance
Antecedents for Cyberloafing – A Literature Review
Internal Crowd Work as a Source of Empowerment - An Empirical Analysis of the Perception of Employees in a Crowdtesting Project
Track 14: Geschäftsmodelle und digitales Unternehmertum
Dividing the ICO Jungle: Extracting and Evaluating Design Archetypes
Capturing Value from Data: Exploring Factors Influencing Revenue Model Design for Data-Driven Services
Understanding the Role of Data for Innovating Business Models: A System Dynamics Perspective
Business Model Innovation and Stakeholder: Exploring Mechanisms and Outcomes of Value Creation and Destruction
Business Models for Internet of Things Platforms: Empirical Development of a Taxonomy and Archetypes
Revitalizing established Industrial Companies: State of the Art and Success Principles of Digital Corporate Incubators
When 1+1 is Greater than 2: Concurrence of Additional Digital and Established Business Models within Companies
Special Track 1: Student Track
Investigating Personalized Price Discrimination of Textile-, Electronics- and General Stores in German Online Retail
From Facets to a Universal Definition – An Analysis of IoT Usage in Retail
Is the Technostress Creators Inventory Still an Up-To-Date Measurement Instrument? Results of a Large-Scale Interview Study
Application of Media Synchronicity Theory to Creative Tasks in Virtual Teams Using the Example of Design Thinking
TrustyTweet: An Indicator-based Browser-Plugin to Assist Users in Dealing with Fake News on Twitter
Application of Process Mining Techniques to Support Maintenance-Related Objectives
How Voice Can Change Customer Satisfaction: A Comparative Analysis between E-Commerce and Voice Commerce
Business Process Compliance and Blockchain: How Does the Ethereum Blockchain Address Challenges of Business Process Compliance?
Improving Business Model Configuration through a Question-based Approach
The Influence of Situational Factors and Gamification on Intrinsic Motivation and Learning
Evaluation von ITSM-Tools für Integration und Management von Cloud-Diensten am Beispiel von ServiceNow
How Software Promotes the Integration of Sustainability in Business Process Management
Criteria Catalog for Industrial IoT Platforms from the Perspective of the Machine Tool Industry
Special Track 3: Demos & Prototyping
Privacy-friendly User Location Tracking with Smart Devices: The BeaT Prototype
Application-oriented robotics in nursing homes
Augmented Reality for Set-up Processe
Mixed Reality for supporting Remote-Meetings
Gamification zur Motivationssteigerung von Werkern bei der Betriebsdatenerfassung
Automatically Extracting and Analyzing Customer Needs from Twitter: A “Needmining” Prototype
GaNEsHA: Opportunities for Sustainable Transportation in Smart Cities
TUCANA: A platform for using local processing power of edge devices for building data-driven services
Demonstrator zur Beschreibung und Visualisierung einer kritischen Infrastruktur
Entwicklung einer alltagsnahen persuasiven App zur Bewegungsmotivation für ältere Nutzerinnen und Nutzer
A browser-based modeling tool for studying the learning of conceptual modeling based on a multi-modal data collection approach
Exergames & Dementia: An interactive System for People with Dementia and their Care-Network
Workshops
Workshop Ethics and Morality in Business Informatics (Workshop Ethik und Moral in der Wirtschaftsinformatik – EMoWI’19)
Model-Based Compliance in Information Systems - Foundations, Case Description and Data Set of the MobIS-Challenge for Students and Doctoral Candidates
Report of the Workshop on Concepts and Methods of Identifying Digital Potentials in Information Management
Control of Systemic Risks in Global Networks - A Grand Challenge to Information Systems Research
Die Mitarbeiter von morgen - Kompetenzen künftiger Mitarbeiter im Bereich Business Analytics
Digitaler Konsum: Herausforderungen und Chancen der Verbraucherinformati