A system for the simultaneous delivery of intraoperative radiation and ultrasound hyperthermia

A multi-element ultrasonic applicator, utilizing an ultrasound reflector, is presented which enables the controlled delivery of ultrasonic energy for the induction of hyperthermia while allowing the simultaneous application of orthovoltage ionizing radiation. A temperature-controlled water circulating system allows for acoustic coupling, additional control over the tumour surface temperature and depth of maximum temperature into the tissue. In vitro and in vivo testing supported the applicators objective of effectively controlling temperature elevation. Therapeutic target temperatures of 42 degrees C can be achieved within a 5-min period and maintained for a 60-min treatment time. The depth of heat penetration could be varied as a function of surface temperature and ultrasound frequency. Heating was achieved to at least a depth of 3 cm. Radiation measurement methods verified the expected radiation dose uniformity and distribution.