Improved hardware stability and signal amplification in a medical microwave radiometer

Abstract

Breast cancer is one of the most frequent types of cancer in the female population today. Modern diagnostic modalities, while proven to be helpful within large scale screening programs, are inherently limited with regards to specificity and sensitivity, and use active methods for acquisition of information. A passive and non-invasive method for detection and diagnostic purposes could therefore be a valuable asset to the existing technology.

One such method is microwave radiometry. A microwave radiometer is an instrument for non-invasive thermography of subcutaneous temperatures. Recent advances within the field has demonstrated that this technology could be helpful in conjunction with existing methods.

This thesis presents the design, implementation and experimental verification of a miniaturized medical microwave radiometer. The design is based on the Switch-Circulator Dicke-configuration to minimize effects of gain variations and mismatch at the antenna input.

The performance of the radiometric system is verified through phantom experiments with a hot object embedded at various depths in a homogeneous, lossy medium. Results display a good coherence with regards to linearity, temperature sensitivity and repeatability. For an integration time constant of 2s, the temperature resolution is found to be approximately 0.07C, which is comparable with similar instruments as reported in literature.