Internal Body Temperature Measurements Using a Miniaturized Hybrid Radiometer

Monitoring internal body temperature is important in many medical applications. For example, hyperthermia is currently used as a treatment for cancer, either independently by increasing the temperature of the cancer tissues above 48 to 50°C or in combination with chemotherapy at lower temperatures ranging from 40 to 45°C (Stauffer, P. R., et al. “Thermal therapy applications of electromagnetic energy.” Biological and Medical Aspects of Electromagnetic Fields, Fourth Edition (2018): 305–343). When this radio-frequency heating is performed, it is essential to measure the temperature increase not only of the cancer tissue, but also of surrounding tissues. Another example is the need to noninvasively measure brain temperature during cardiac surgery when the blood supply is interrupted and the brain needs to be cooled by up to 15° and then brought back to normal temperature. Currently, there are no commercially available non-invasive methods for measuring body temperature at a few cm depth. Existing internal body temperature monitoring methods include nasal catheters, needle probes, and MRI, which are invasive, expensive, and/or non-wearable. Microwave radiometry is a non-invasive and compact method to measure internal body temperature.