In vivo dielectric spectrometer

An instrument is described for measuring the relative permittivity and dielectric loss of body tissues and organsin vivo, over the frequency range 0·1 Hz to about 100 kHz. A voltage transient is applied by means of suitable electrodes and the resulting waveform is sampled, digitised and Fourier transformed using a microprocessor to give a spectrum in the frequency domain. The results show differences in relative permittivity and dielectric loss between different types of tissue. Much of the preliminary clinical work with this apparatus has been done using measurements on breast tumours.