Analysis of temperature measurement for monitoring radio-frequency brain lesioning.

During ablative neurosurgery of movement disorders, for instance therapy of Parkinson's disease, temperature monitoring is crucial. This study aims at a quantitative comparison of measurement deviations between the maximum temperature located outside the lesioning electrode and two possible thermocouple locations inside the electrode. In order to obtain the detailed temperature field necessary for the analysis, four finite element models associated with different surroundings and with different power supplies are studied. The results from the simulations show that both the power level and the power density as well as the surrounding medium affect the temperature measurement and the temperature field in general. Since the maximum temperature is located outside the electrode there will always be a deviation in time and level between the measured and the maximum temperature. The deviation is usually 2-7 s and 3-12 degrees C, depending on, for example, the thermocouple location and surrounding medium. Therefore, not only the measured temperature but also the relation between measured and maximum temperature must be accounted for during therapy and device design.