Exposure limits and dielectric contrast for breast cancer tissues: Experimental results up to 50 GHz

At microwave and mm-wave frequencies, the interactions of the human tissue with electromagnetic fields depend on the dielectric properties of the tissue itself. The knowledge of these properties of healthy and malignant tissues, beyond to be crucial in several biomedical applications, is necessary to fix the safety thresholds in policy-making and the exposure limits for the human body. In particular, breast tissues are of particular interest from the medical and social point of view due to the relatively large diffusion of breast cancer. In literature, experimental data are available up to 20 GHz, and consequently at mm-wave frequencies they are only derived from extrapolations. This paper presents a feasibility study based on the experimental results of a broadband dielectric characterization of breast tissues up to 50 GHz. In particular, two main aspects are addressed. First, the contrast achievable between normal and tumorous tissues, a key parameter for several biomedical applications. Second, the compliance of a mm-wave imaging system for breast cancer detection with the ICNIRP recommendations.