Measurements and analysis of the microwave dielectric properties of tissues

摘要: Knowledge of the microwave dielectric properties human tissues is essential for understanding and development medical techniques. In particular, thermography relies on processes fundamentally determined by high frequency electromagnetic tissues. The specific aim this work was to provide detailed information female breast tissue at 3-3.5GHz, operation Glasgow equipment. At frequences variation biological thought be mainly dipolar relaxation water. Water exists in different states binding within tissue; each component water may parameterised Debye or Cole-Cole equations. a single an average calculated given type. Mixture equations used describe two-phase mixtures terms volume fractions phases. Biological are very much more complex than these two phase models. However, comparisons observed as function content, with models from mixture theory allow some qualitative conclusions drawn regarding structure. Human animal data frequencies between 0.1 10GHz have been collected literature displayed tabular form. These comprehensive tables were examine widely-held assumption representative corresponding tissue. This concluded uncertain most cases because lack available data, perhaps wrong certain types. also compare vivo vitro data. expected physiologically abnormal state vitro. However found provided gross deterioration avoided. A new resonant cavity perturbation technique designed measurements small volumes lossy materials fixed 3.2GHz. measure wide range permittivities conductivities accuracies 3-4%. major sources error heterogeneity sample preparation procedures. Using made large number gathered fat normal tissues, benign malignant tumours. Each set using equation. Results suggest that all measured contain bound smaller proportion other Comparisons values theories. Permittivity largely fall bounds theory: conductivity often outside limits. imply physiological saline not good approximation waters; it another process occurring addition saline. type indicate imaging system could which would detect diseases, but severe problems arise distinguishing disease types alone.