In vivo and online temperature monitoring based on fiber Bragg greatings during tumor treatment with nanosecond pulse electric field

A fiber Bragg grating (FBG) sensing system was used to online monitor the temperature at the surface of / inside the liver tissue of a rabbit under nanosecond pulse electric field (nsPEF). Single point measurement between the electrodes and multi-point measurement surrounding one electrode were both carried out. Experimental results show that, due to equally spaced (Δt=0.5 s) 300 ns-pulses with E=20 kV/cm at a repetition rate of 4 Hz, the temperature rise in the rabbit liver tumor usually does not exceed ΔT=6°C for 300 pulses. Theoretical analysis of Joule heating model fits well with the experimental results. Both direct measurements and theoretical modelling demonstrated that nsPEF could not deliver enough energy to heat the treated tissue significantly, thus a hyperthermic effect on the tissue can be excluded during this kind of treatment with much high electric field strength and extremely short duration.