Ultrasound heating methods for hyperthermic therapy
Journal
Journal of Medical Ultrasound
Journal Volume
2
Journal Issue
3
Pages
113-120
Date Issued
1994
Author(s)
Abstract
During the 1950s and 1960s, several studies investigated the combined effects of ultrasound and radiation; the results obtained were encouraging. The therapeutic effect of sonication was found to be caused by temperature elevation in the tissue. These studies led to the conclusion that ultrasound used only in combination with radiotherapy leads to beneficial effects. In the same period, high-intensity ultrasound was used to produce lesions in both animal and human central nervous systems for surgical purposes. From these experiments, it was observed that tissue damage was caused by the temperature elevation in the focal zone producing coagulation necrosis. The intensity threshold for the production of the lesions was found to be dependent on time. This high intensity technique, with intensity levels high enough to produce coagulation necrosis, has also been used in cancer therapy. In the early 1970s, there was renewed interest in using elevated temperatures in cancer therapy and it was soon shown that a suitable treatment (temperature above 42.5°C for 30-60 minutes) has a cytotoxic effect both in vitro and in vivo. This encouraged the method of tumor heating in a clinical setting. It was not until the end of the 1970s that the potential of ultrasound as a method of inducing hyperthermia was shown. However, it has not become as popular a method as microwave-induced hyperthemia, despite its many advantages. The main reason for this lack of popularity is that the devices required for tumor-heating are fairly complex and have not yet become commercially available. At present, ultrasound appears to offer good control over the resultant temperature distribution in the needed sites. In addition, it appears to be the only noninvasive method capable of inducing therapeutic temperatures in deep tumors. The main difficulty in clinically testing ultrasound hyperthermia is the lack of commercial equipment with enough flexibility to heat various tumors routinely.
SDGs
Other Subjects
cancer radiotherapy; human; hyperthermia; instrumentation; review; ultrasound therapy
Publisher
Elsevier (Singapore) Pte Ltd
Type
review