Uncertainty in computational RF dosimetry
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Journal Title
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Sähkötekniikan korkeakoulu |
Doctoral thesis (article-based)
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Author
Date
2011
Major/Subject
Mcode
Degree programme
Language
en
Pages
Verkkokirja (1539 KB, 65 s.)
Series
Aalto University publication series DOCTORAL DISSERTATIONS ,
3/2011
Abstract
Radio-frequency (RF) electromagnetic field dosimetry studies the absorption of electromagnetic energy inside the human body. The absorbed energy is measured in terms of the specific absorption rate (SAR), which is linked to the possible adverse thermal effects of the exposure to RF electromagnetic fields. With advances in computational power and accurate numerical models of the human anatomy, computational methods have gained an increasingly significant role in RF dosimetry in recent years. Nowadays, the finite-difference time-domain (FDTD) method is the most widely used numerical technique in computational RF dosimetry. Computational analysis of the SAR features many modelling and approximation phases that may introduce error and uncertainty. The emphasis of this thesis is to study how reliably the SAR can be assessed by the FDTD method, and how various modelling choices affect the accuracy of the simulated results. In addition to the SAR, also the temperature rise due to the electromagnetic power absorption and its modelling by the bioheat equation is studied. The results of the thesis help to evaluate and identify the possible uncertainty factors and sources of error in computational RF dosimetry, which will produce new information on the reliability and repeatability of computational exposure assessment. Studying the uncertainty and accuracy of the methods also allows, for example, lessening the computational requirements and improving the accuracy of the simulations.Description
Supervising professor
Nikoskinen, Keijo, Prof.Thesis advisor
Nikoskinen, Keijo, Prof.Keywords
computational dosimetry, finite-difference methods, specific absorption rate, bioheat equation
Other note
Parts
- [Publication 1]: Ilkka Laakso, Sami Ilvonen, and Tero Uusitupa. 2007. Performance of convolutional PML absorbing boundary conditions in finite-difference time-domain SAR calculations. Physics in Medicine and Biology, volume 52, number 23, pages 7183-7192. © 2007 Institute of Physics Publishing (IOPP). By permission.
- [Publication 2]: Ilkka Laakso and Tero Uusitupa. 2008. Alternative approach for modeling material interfaces in FDTD. Microwave and Optical Technology Letters, volume 50, number 5, pages 1211-1214. © 2008 Wiley Periodicals. By permission.
- [Publication 3]: T. M. Uusitupa, S. A. Ilvonen, I. M. Laakso, and K. I. Nikoskinen. 2008. The effect of finite-difference time-domain resolution and power-loss computation method on SAR values in plane-wave exposure of Zubal phantom. Physics in Medicine and Biology, volume 53, number 2, pages 445-452. © 2008 Institute of Physics and Engineering in Medicine (IPEM). By permission.
- [Publication 4]: Ilkka Laakso. 2009. Assessment of the computational uncertainty of temperature rise and SAR in the eyes and brain under far-field exposure from 1 to 10 GHz. Physics in Medicine and Biology, volume 54, number 11, pages 3393-3404. © 2009 Institute of Physics and Engineering in Medicine (IPEM). By permission.
- [Publication 5]: T. Uusitupa, I. Laakso, S. Ilvonen, and K. Nikoskinen. 2010. SAR variation study from 300 to 5000 MHz for 15 voxel models including different postures. Physics in Medicine and Biology, volume 55, number 4, pages 1157-1176. © 2010 Institute of Physics and Engineering in Medicine (IPEM). By permission.
- [Publication 6]: Ilkka Laakso, Tero Uusitupa, and Sami Ilvonen. 2010. Comparison of SAR calculation algorithms for the finite-difference time-domain method. Physics in Medicine and Biology, volume 55, number 15, pages N421-N431. © 2010 Institute of Physics and Engineering in Medicine (IPEM). By permission.
- [Publication 7]: Sami Ilvonen and Ilkka Laakso. 2009. Computational estimation of magnetically induced electric fields in a rotating head. Physics in Medicine and Biology, volume 54, number 2, pages 341-351. © 2009 Institute of Physics and Engineering in Medicine (IPEM). By permission.
