Position: Postdoctoral Researcher
Current Institution: National University of Ireland – Galway
Confounders in Dielectric Properties of Biological Tissues and the Impact on Electromagnetic Medical Applications
The dielectric properties of biological tissues are of fundamental importance to understanding and quantifying the interaction of electromagnetic fields with the human body. These quantities determine the transmission, reflection, and absorption of electromagnetic fields within the body. Accurate knowledge of the dielectric properties of human tissues are vital for many applications. In particular, they are used to evaluate the safety of wireless electronic devices and communications, and in the design and development of electromagnetic medical imaging and therapeutic devices. The dielectric properties often play a role in determining the operating requirements of such devices, including the minimum input (transmitted) power and the functional frequency range. Historically, studies reported in the literature have aimed to establish a database of dielectric properties for many human tissues; however, rather than solidifying existing data, such studies have often produced conflicting results, a fact which is likely attributable to the considerable differences in measurement approaches and techniques used at all stages of dielectric property studies. Dielectric measurements are typically performed by placing an open-ended coaxial probe in contact with the tissue sample, and recording the reflection coefficient with a vector network analyser. While uncertainties occur due to the measurement equipment (e.g. drift, random noise, cable movements), the uncertainties attributed to clinical factors are orders of magnitude higher. Clinical factors result from measurements on tissues in an uncontrolled environment; examples of causes for clinical uncertainties include the quality and pressure of the probe-sample contact, the sample temperature, the ambient humidity, and poor quantification of the types of tissues that are present in heterogeneous samples. This work presents an exhaustive investigation of two key clinical factors, the probe sensing depth and the process of attribution of measured dielectric properties to samples with heterogeneous tissue contents. The findings demonstrate that significant error can be introduced to the dielectric properties of tissues when using common assumptions relating to these two key clinical factors. A framework is presented for quantifying these factors, enabling future dielectric property studies to obtain results that are meaningful, repeatable, and traceable.
Emily Porter is a Postdoctoral Researcher and Adjunct Lecturer in the Lambe Medical Device Group at the Translational Research Facility (University Hospital Galway), National University of Ireland-Galway (NUIG). Her research is focused on novel medical applications of electromagnetics. In particular, her interests include bladder and kidney monitoring using electrical impedance tomography, microwave radar for breast cancer diagnosis and treatment, anatomically and electrically realistic phantoms, and standardized dielectric measurements of biological tissues. Such electromagnetic medical devices have significant potential to enhance health diagnosis strategies and treatment outcomes, through non-invasive techniques with minimal side-effects. Dr. Porter is an active member in a European Cooperation in Science and Technology (COST) Action, named “TD1301: Accelerating the Technological, Clinical and
Commercialisation Progress in the Area of Medical Microwave Imaging,” which consists of over
160 members in 26 countries.
Emily Porter studied at McGill University, Montreal, Canada, where she received her M. Eng. in 2010 and her Ph.D. in Applied Electromagnetics in 2015. During her time at McGill University, she also worked as an editor and proofreader for technical publications. Her Ph.D. research focused on the design and implementation of a microwave breast health monitoring device, which is currently undergoing early clinical studies at the McGill University Health Centre’s Breast Clinic at the Royal Victoria Hospital (Montreal). Initial results of the study have been published in IEEE Transactions on Biomedical Engineering and IEEE Transactions on Medical Imaging. Dr. Porter is the recipient of several prestigious national and international awards, including the IEEE Antennas and Propagation Society Doctoral Research Award, the Irish Research Council (IRC) “New Foundations” Grant, the Royal Irish Academy (RIA) Charlemont Grant, the Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship, Le Fonds de recherche du Québec – Nature et technologies (FRQNT) Fellowship (Research Fund of Quebec: Nature and Technologies), and the D.W. Ambridge
Dr. Porter is the recipient of several prestigious national and international awards, including the IEEE Antennas and Propagation Society Doctoral Research Award, the Irish Research Council (IRC) “New Foundations” Grant, the Royal Irish Academy (RIA) Charlemont Grant, the Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship, Le Fonds de recherche du Québec – Nature et technologies (FRQNT) Fellowship (Research Fund of Quebec: Nature and Technologies), and the D.W. Ambridge Prize, awarded by McGill University for the most outstanding graduating doctoral student in Natural Sciences or Engineering.