A microwave hyperthermia system developed for producing controlled localized superficial heating in the treatment of cancer is described. The system is based on a Research Machines 380Z microcomputer acting as a data collector and controller. Accurate multipoint temperature monitoring and production of controlled temperature elevations in the heated tumour/normal tissue volume are important requirements for successful treatment with hyperthermia. Temperatures at up to twelve selected points can be monitored using single and multijunction copper/constantan thermocouples. The temperature data are displayed graphically on a video terminal and a multipen digital plotter, and numerically on a visual display unit and a printer during the treatment. Temperature measurements are made at thirty-second intervals and power is switched off automatically for two seconds before measurements to minimize errors due to interference. This delay can be increased if necessary during the treatment. Power delivered to the tissue is also monitored automatically. The different clinical requirements of the system are discussed. The effectiveness of the heat treatment is evaluated by monitoring in real time the thermal dose, calculated on the basis of a well established temperature-time relationship, delivered to the heated tissue volume at the measurement points. Use of a microcomputer enables the collection and display of these different important clinical data to be performed efficiently and to provide an optimum treatment for the patient. Essential hardware and software details of the system are described. Examples of temperature distributions obtained in animal and human patients are illustrated.
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