Sensitivity analysis of microwave radiometry for the detection of tumors

The sensitivity of microwave radiometry for detecting subcutaneous targets was studied both experimentally and theoretically. Rectangular aperture antennas were used with a 4.7-GHz Dicke radiometer to detect thermal and dielectric inhomogeneities in otherwise homogeneous media. A theoretical model was developed to predict the amplitude of the received signal as functions of the size of the antenna, the dielectric properties of the surrounding tissue and the size, dielectric properties, position and orientation of the target with respect to the antenna. The model was based on calculations of the pattern of power deposition from the antennas, and application of the reciprocity theorem. As expected, the target´s size, temperature and location greatly affect the measured temperature. Detection of the target becomes much more difficult as it becomes smaller, cooler and farther from the antenna. Decreasing the antenna size (to improve its lateral resolution) greatly decreases the depth at which the target can be detected. This study has quantified the effects of these parameters on the ability of microwave radiometry to detect subcutaneous thermal anomalies.<>