New-born-infant brain temperature measurement by microwave radiometry

Abstract

Hypothermia of the new-born-infant brain has been proposed as a neuroprotective therapy after hypoxia-ischaemia. At a preliminary stage of the new therapy the knowledge of the achievable brain temperature is desirable as well as its variation with time during treatment. There is the need, therefore, for non-invasive temperature measurement during hypothermia treatments. Multifrequency microwave radiometry has been considered for the measurement of the baby-head temperature during therapeutic cooling. Thermal and electromagnetic models for the baby head are required. A thermal model of the cooling has been arranged from the Pennes equation and data found in literature and the model used to generate the synthetic data to be exploited in temperature reconstruction. The inverse problem has been formulated in two different ways: (a) a retrieval based on a thermal model fitting by matrix pencil and least square minimisation; (b) a finite state-space approach with Kalman filtering of data. A numerical analysis has been performed showing that the radiometric measurements can partially compensate for errors in the model provided the temperature profile belongs to the class of functions specified by the model.