Influence of the permittivity of breast tissues on the robustness of microwave radiometric imaging

Microwave radiometric imaging (MWI) is a passive method of thermal investigation which allows the observation of subcutaneous thermal gradient. Recently, the authors have defined a method of inversion by deconvolution and Wiener filtering, which leads to a consequent improvement of the spatial resolution in the case of compact thermal structures. One of the applications the authors are considering is the detection of possible thermal gradients associated to nonpalpable breast tumors. For this reason, they have tested this method for different cases of known permittivities of breast tissues. The conclusion of this simulation shows the robustness of the inversion process even if the permittivity of the tissues is not exactly known. Positive results have been registered in the field using MWI, which are summarised here. Encouraging conclusions have been obtained during a clinical evaluation related to the characterisation (malignancy or benignity) of nonpalpable breast tumors. A new radiometric imaging system is now being built, which allows the acquisition of the radiometric image in a reasonable time interval (an image obtained in four minutes). The spatial resolution of the images is improved by application of deconvolution and Wiener filtering.