Simultaneous combination of external superficial hyperthermia and photon beam radiation therapy on a 6 MV linear accelerator

An increased biological effect is seen when hyperthermia and radiation therapy are combined simultaneously. In order to take advantage of this effect we have developed techniques which combine existing hyperthermia devices with a linear accelerator and which allow the concomitant delivery of both ultrasound and microwave hyperthermia with photon radiation therapy. Two techniques have been used clinically: the orthogonal technique, in which the microwave or hyperthermia beam and the radiation beam are orthogonal to one and other, and the en face technique in which the ultrasound or hyperthermia beam and the radiation beam travel into the tumor through the same treatment window. The en face technique has necessitated the development of special attachments so that the hyperthermia device can be mounted to the linear accelerator and so that non uniform portions of the hyperthermia device can be removed from the hyperthermia beam. For microwave therapy this has necessitated the mounting of the applicators onto the linear accelerator using the compensating filter tray holder. For ultrasound this has necessitated the use of special reflector devices which are mounted to a frame which can be mounted onto the compensating filter tray holder of the linear accelerator.