Effects of tissue layering on microwave thermography

Non-invasive thermal imaging and temperature measurement by microwave radiometry has been investigated, for medical diagnostic applications and monitoring hyperthermia treatment of cancer, in the context of the heterogeneous body structure. The temperature measured by a radiometer is a function of the emission and propagation of microwaves in tissue and the receiving characteristics of the radiometric probe. Propagation of microwaves in lossy media was analyzed by a spectral diffraction approach. Extension of this technique via a cascade transmission line model provides an efficient algorithm for predicting the field patterns of aperture antennas contacting multi-layered tissue. A coherent radiative transfer analysis was used to relate the field pattern of a radiating antenna to its receiving characteristics when used as a radiometer probe, leading to a method for simulating radiometric data. Measurements and stimulations were used to assess the effect of overlying fat layers upon radiometer response to temperature hot-spots in muscle-type media