<title>Comparative studies on hyperthermia induced by laser light, microwaves, and ultrasonics</title>

Abstract

Therapeutic heating takes back as far as 3000 B.C., but the therapeutical use of local temperature rise of 5_200 C above normal body temperature, called hyperthermia, was carried out only in the past few decades if we disregard moxibustion. Results obtained by various treatment modalities such as optical waves (laser light), microwaves (MW), radio frequency current (RE) or ultrasound (US) are compared, and a theory based on the assumption that tumor formation can be regarded as some sort of disturbance in the signal processing system of the given biological structure is presented, suggesting that not the locally generated heat alone, but the elevated temperature in relation to several environmental factors is responsible for cell killing. Therefore, the modality of creating hyperthermia may be of significance since various methods may change the thermal behavior of the cell environment in a specific way, which means that using two or more modalities the synergetic behavior could be exploited for a better result.

A theoretical comparison of energy sources - microwave, ultrasound and laser - for interstitial thermal therapy

“…Few studies have compared the ability of different heating modalities to deliver energy for thermal therapy. Comparative studies have been conducted in the past in the hyperthermia temperature range, 40-45 • C (Greguss 1991), but these have mainly focused on the mechanisms causing cell death, rather than evaluating the relative effectiveness of the various modalities in depositing power in tissue.…”