Improved thermometry system for ultrasound hyperthermia

Abstract

A thermometry system for use during ultrasound hyperthermia treatments was developed to provide fast and reliable temperature measurements such that transient temperatures from multi-sensor thermocouples could be measured. It was also intended to provide electrical isolation for patient safety when bare thermocouple sensors were used in order to reduce artifacts. The system hardware development involved fabrication of a high precision temperature measurement box which was electrically isolated from, by an opto-isolation unit, and interfaced with, an 386-20 MHz personal computer. The system software development involved a two point calibration program for each thermocouple probe to be used with the system, and a sensor locating program to rapidly identify the probe locations immediately prior to treatment. A single scan temperature reading speed of 0.2 sec for all 112 thermocouple sensors with an average accuracy of ±0.05°C under normal operating conditions (ambient temperature 22°C to 28°C) was achieved. A probe to earth ground leakage sink current of 75 μA and a leakage source current of less than 10 μA was attained.