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Limited angle reconstruction for 2D CT based on machine learning
KTH, School of Engineering Sciences (SCI).
KTH, School of Engineering Sciences (SCI).
2023 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

The aim of this report is to study how machine learning can be used to reconstruct 2 dimensional computed tomography images from limited angle data. This could be used in a variety of applications where either the space or timeavailable for the CT scan limits the acquired data.In this study, three different types of models are considered. The first model uses filtered back projection (FBP) with a single learned filter, while the second uses a combination of multiple FBP:s with learned filters. The last model instead uses an FNO (Fourieer Neural Operator) layer to both inpaint and filter the limited angle data followed by a backprojection layer. The quality of the reconstructions are assessed both visually and statistically, using PSNR and SSIM measures.The results of this study show that while an FBP-based model using one or more trainable filter(s) can achieve better reconstructions than ones using an analytical Ram-Lak filter, their reconstructions still fail for small angle spans. Better results in the limited angle case can be achieved using the FNO-basedmodel.

Place, publisher, year, edition, pages
2023.
Series
TRITA-SCI-GRU ; 2023:177
Keywords [en]
CT, computed tomography, limited angle, machine learning, limited data, ill posed problem, inverse problem
National Category
Mathematics
Identifiers
URN: urn:nbn:se:kth:diva-331367OAI: oai:DiVA.org:kth-331367DiVA, id: diva2:1781241
Subject / course
Numerical Analysis
Educational program
Master of Science in Engineering -Engineering Physics
Supervisors
Examiners
Available from: 2023-07-07 Created: 2023-07-07 Last updated: 2023-07-07Bibliographically approved

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CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf