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Patient-induced susceptibility effects simulation in magnetic resonance imaging
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2017 (English)In: Physics and Imaging in Radiation Oncology, ISSN 2405-6316, Vol. 1, 41-45 p.Article in journal (Refereed) Published
Abstract [en]

AbstractBackground and purpose A fundamental requirement for safe use of magnetic resonance imaging (MRI) in radiotherapy is geometrical accuracy. One factor that can introduce geometrical distortion is patient-induced susceptibility effects. This work aims at developing a method for simulating these distortions. The specific goal being to help objectively identifying a balanced acquisition bandwidth, keeping these distortions within acceptable limits for radiotherapy. Materials and methods A simulation algorithm was implemented in Medical Interactive Creative Environment (MICE). The algorithm was validated by comparison between simulations and analytical solutions for a cylinder and a sphere. Simulations were performed for four body regions; neck, lungs, thorax with the lungs excluded, and the pelvic region. This was done using digital phantoms created from patient CT images, after converting the CT Hounsfield units to magnetic susceptibility values through interpolation between known values. Results The simulations showed good agreement with analytical solutions, with only small discrepancies due to pixelation of the phantoms. The calculated distortions in digital phantoms based on patient CT data showed maximal 95th percentile distortions of 39%, 32%, 28%, and 25% of the fat-water shift for the neck, lungs, thorax with the lungs excluded, and pelvic region, respectively. Conclusions The presented results show the expected pixel distortions for various body parts, and how they scale with bandwidth and field strength. This information can be used to determine which bandwidth is required to keep the patient-induced susceptibility distortions within an acceptable range for a given field strength.

Place, publisher, year, edition, pages
2017. Vol. 1, 41-45 p.
Keyword [en]
MRI, Susceptibility, Radiotherapy, Distortions
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:umu:diva-137453DOI: 10.1016/j.phro.2017.02.004OAI: oai:DiVA.org:umu-137453DiVA: diva2:1119060
Available from: 2017-07-03 Created: 2017-07-03 Last updated: 2017-07-03

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Publisher's full texthttp://www.sciencedirect.com/science/article/pii/S2405631616300124
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CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • 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