On the Conservation of Materials for Breast Phantoms in the Frequency Range 0.5-50 GHz

Breast cancer is one of the most dangerous female disease worldwide. Currently the trend of incidence rate is growing, however the death rate is decreasing. The merit of these statistics can be also referred to the improvement in available diagnostic tools, which are allowing to make early-diagnosis. Nowadays, several diagnostic methodologies are available, however they are not optimal to be used in a mass screening program, because of their limitations (e.g., patient exposition to ionizing radiations or high costs). For these reasons, recently microwaves and mm-waves have been proposed as a safe and low cost alternative. In particular, mm-waves could offer a suitable compromise between penetration depth, image resolution, and contrast between the dielectric properties of healthy and malignant tissues. A key point for the development of such microwave and mm-wave diagnostic systems is the test phase on realistic breast phantoms. This paper discusses for the first time the conservation of a particular type of easy-to-produce and cheap mixtures used to create breast phantom in the frequency range 0.5-50 GHz. The conservation aspects are fundamental to ensure the repeatability of measurements over time. In particular, this paper shows experimental results performed in a time span of one week, which demonstrate that the best stability for the dielectric properties of the mixtures is achieved when preserving the mixture itself using sunflower seed oil.