Realization of breast tissue-mimicking phantom materials: dielectric characterization in the 0.5-50 GHz frequency range

Breast cancer is the most widespread disease among women around the world. However, thanks to the improvement in knowledge about cancer, it is becoming more treatable and curable. In recent years, the interest toward the use of radiofrequencies for diagnostic and screening purposes has been growing, with particular attention for microwaves and mm-waves. These frequencies in principle give the possibility of making a diagnosis without risks and involving low cost instrumentation. Past dielectric characterizations of human breast samples have shown that a significant difference is present between healthy and malignant tissues, and that a reasonable penetration depth is possible for detecting a cancer of some millimeters, even in the mm-wave frequency range. A fundamental step toward the development of these systems is the test phase on breast phantoms. Several tissue-mimicking materials have been proposed, but the presence of a number of drawbacks is pushing the research for different agents and/or mixtures to be used for this purpose. In this paper, the dielectric characterization of easy-to-produce and cheap mixtures mimicking the dielectric properties of human breast healthy tissues up to 50 GHz is presented. Similar mixtures are currently used for ultrasound breast phantoms, and so far they have been unexplored in the radiofrequency regime. All measurements have been compared to the data derived from the dielectric characterization of human breast samples, and the good agreement between them shows that they could be an excellent alternative to the current tissue mimicking materials.