Physical Point of View

Abstract

The question as to which regions of the human body may be heated adequately using currently available techniques can be answered as follows. Superficial tumours at depths of 3–4 cm can be heated and their temperatures controlled reasonably well using microwave methods or low-radiofrequency methods. Ultrasound methods may produce heating at slightly greater depths. Our ability to heat deep-seated tumours, however, must be looked at more pessimistically. Several groups are investigating this very difficult problem. There are many physical and physiological problems, which must be carefully studied if we are to progress with electromagnetically induced regional heating. If deep localized heating can be induced by ultrasound, concurrent improvements in thermometric techniques will be required. However, interstitial methods are capable of heating rather large volumes relatively uniformly and are applicable to both superficial sites and those deep in the body. A further advantage is that many of these methods can be combined with interstitial brachytherapy.