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An Evaluation of Kilo Voltage Image Quality Produced by an On-Board Imager System
KTH, School of Information and Communication Technology (ICT).
2015 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [sv]

Syfte: Syftet med detta projekt var att utvärdera kvaliteten på de digitala röntgenbilder som genereras med en On-Board imager® (OBI), monterad på en medicinsk linjäraccelerator på radioterapiavdelningen på Karolinska Universitetssjukhuset. Dessa kilovoltbilder används för att verifiera patientens position på behandlingsbordet, inför behandling, för att reducera risken att friskvävnad bestrålas i onödan. Detta utförs genom en online ortogonal 2D-2D matchningsteknik innan strålningen leveras. Material och metoder: OBI-system, utvecklad av Varian Medical System, erbjuder en protokoll med exponeringsparametrar för att hjälpa användaren att välja lämpliga inställningar för exempelvis lämplig rörström och spänning under bildtagningen de digitala kilovoltbilderna. Under detta projekt skapades flera testbilder tagna med ändrade exponeringsparametrarna i de befintliga protokollen. Dessa testbilders kontrast bedömdes sedan och jämfördes med bilder tagna med de förinställda parametrar från Varians protokoll. Resultat och slutsats: En utvärdering av de experimentella testbilderna, i jämförelse med bilder skapade med det befintliga protokollet, visade att en justering av exponeringsfaktorer inte leder till något signifikant förbättring av bildernas kontrast.

Abstract [en]

Purpose: The purpose of this project was to evaluate the quality of kilo Voltage- digital radiography images that are provided by an On-Board imager® (OBI) mounted on a medical linear accelerator at the Radiotherapy department of Karolinska University Hospital. The digital kV-images are used to verify patient position on the treatment table, in order to reduce healthy tissue irradiation, using an online orthogonal set of 2D-2D matching technique, before the treatment delivery. Material and methods: The OBI- system elaborated by Varian Medical System offers an exposure factor protocol in order to help users to choice proper exposure factors, as proper tube current and tube voltage, during acquisition of kV-images. In this project several test images were performed by changing the exposure factors. Further the test images quality regarding, quality index contrast, was assessed and compared with the image performed by the existent Varian protocol. Result and Conclusion: Evaluation of the tests images shows that changing of the exposure factors doesn’t result in any significant improvement of kV-images contrast as compared to images created with the existent protocols parameters.

Place, publisher, year, edition, pages
2015.
Series
TRITA-ICT-EX, 2015:52
Keyword [en]
Key Words: Exposure factors, Tube Voltage, Tube current, Contrast
Keyword [sv]
Exponeringsfaktorer, Rörspänning, Rörström, Kontrast
National Category
Computer and Information Science
Identifiers
URN: urn:nbn:se:kth:diva-175344OAI: oai:DiVA.org:kth-175344DiVA: diva2:860383
Examiners
Available from: 2015-10-12 Created: 2015-10-12 Last updated: 2017-06-14Bibliographically approved

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CiteExportLink to record
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