Computer-controlled temperature multiplexer for thermal dosimetry studies

Thermistor probes are widely used for mapping thermal distributions in hyperthermia research. To facilitate multi-probe mapping, a computer-controlled multiplexer for automated thermistor impedance measurement and temperature conversion is described. A complete hardware interface schematic is shown. An algorithm which calculates individual temperature values as a function of thermistor impedance is tested. Total error is quantified by calculating the absolute error between the theoretical temperatures obtained from the algorithm and the experimental calibration temperatures obtained from a National Bureau of Standards referenced mercury thermometer. If calibration intervals of 1.00 degree C or less are used, the total error of the system is less than 0.10 degree C.