Modelling of wave equations obeying frequency dependent attenuation laws for thermoacoustic Tomography
R. Kowar (University of Innsbruck)
It is reasonable that the resolution in Computed Thermoacoustic Tomography can be improved by
taking the attenuation of the pressure waves inside the tissue into account.
Loosely spoken the classical attenuation law states that a frequency component of a pressure wave is exponentially
damped with an exponent that is proportional to some fractional power $\gamma$ of the absolute value of the
frequency and to the distance from the origin.
For some fractional powers $\gamma$ the solutions of the common models have causality problems which indicate the incompleteness of these models.
In this talk we discuss these causality problems and present a new class of pressure wave equations obeying frequency
dependent attenuation that guarantees causal solutions.