Microwave Reflection and Transmission Measurements for Pulmonary Diagnosis and Monitoring

The potential of using low intensity penetrating microwave energy in diagnosis and monitoring of pulmonary diseases such as edema and emphysema has been investigated theoretically and in selected animal models. These diseases are characterized by changes in total lung water which modify the permittivity and conductivity of the lung tissue, and consequently affect the microwave reflection from or transmission through the lung. Both reflection and transmission measurement techniques have been examined. Animal experiments have indicated changes in microwave reflection with lung water changes. The diagnostic capabilities of transmission measurements have been evaluated experimentally on a phantom model, and theoretically on a planelayered tissue model.