A patient/therapist interactive feedback control system to regulate temperature and control pain in scanned focused ultrasound hyperthermia

Abstract

An interactive temperature and patient pain feedback controller with manual power control as a function of scan position has been developed and clinically implemented in treating cancerous tumors utilizing the University of Arizona Cancer Center's Scanned Focused Ultrasound Hyperthermia system. The temperature controller implemented uses a Bang-Bang PID controller in 12 adjacent regions. The controller is shown to be able to reduce unwanted hot spots without substantially increasing the size of cold spots in the treatment volume. The addition of patient feedback during treatments has reduced the frequency of undesirable treatment modifications such as moving the scan or lowering of ultrasound power. Patients were able to repeatedly indicate the areas of pain with a pain button during treatments allowing a computer to determine the maximum tolerable power without excessive discomfort.