Abstract
Models of tissue dielectric properties (permittivity and conductivity) enable
the interactions of tissues and electromagnetic fields to be simulated, which
has many useful applications in microwave imaging, radio propagation, and
non-ionizing radiation dosimetry. Parametric formulae are available, based on
a multi-pole model of tissue dispersions, but although they give the dielectric
properties over a wide frequency range, they do not convert easily to the time
domain. An alternative is the multi-pole Debye model which works well in both
time and frequency domains. Genetic algorithms are an evolutionary approach
to optimization, and we found that this technique was effective at finding the
best values of the multi-Debye parameters. Our genetic algorithm optimized
these parameters to fit to either a Cole–Cole model or to measured data, and
worked well over wide or narrow frequency ranges. Over 10 Hz–10 GHz the
best fits for muscle, fat or bone were each found for ten dispersions or poles in
the multi-Debye model. The genetic algorithm is a fast and effective method
of developing tissue models that compares favourably with alternatives such as
the rational polynomial fit.
the interactions of tissues and electromagnetic fields to be simulated, which
has many useful applications in microwave imaging, radio propagation, and
non-ionizing radiation dosimetry. Parametric formulae are available, based on
a multi-pole model of tissue dispersions, but although they give the dielectric
properties over a wide frequency range, they do not convert easily to the time
domain. An alternative is the multi-pole Debye model which works well in both
time and frequency domains. Genetic algorithms are an evolutionary approach
to optimization, and we found that this technique was effective at finding the
best values of the multi-Debye parameters. Our genetic algorithm optimized
these parameters to fit to either a Cole–Cole model or to measured data, and
worked well over wide or narrow frequency ranges. Over 10 Hz–10 GHz the
best fits for muscle, fat or bone were each found for ten dispersions or poles in
the multi-Debye model. The genetic algorithm is a fast and effective method
of developing tissue models that compares favourably with alternatives such as
the rational polynomial fit.
| Original language | English |
|---|---|
| Pages (from-to) | 6227-6243 |
| Number of pages | 17 |
| Journal | Physics in Medicine and Biology |
| Volume | 57 |
| Issue number | 19 |
| DOIs | |
| Publication status | Published - 7 Oct 2012 |