We have developed a new prototype of microwave radiometric imaging devoted to the
measurement of the temperature inside a dissipative media. The main application we are
looking for, is the non-invasive thermometry of human tissues. We obtain quite satisfactory
results in the early characterisation of breast tumours in terms of malignancy or benignity. We
have, at this moment in progress, a clinical evaluation of patients that gives good results at an
intermediary stage. To improve the spatial resolution, we have developed an inversion process
based on a regularisation method in the spatial frequency domain, associated with a Deriche
filter for threshold extraction. We show that this process is well suited to our problem and can
be applied to clinical images for a quantitative retrieval of the temperature.