超音波による骨などの発熱のモデル実験について

概要

論文の詳細を見る
The heating phenomenon of bone and other materials by ultrasonic irradiation has been investigated. Metals, whose internal losses are negligible, do not exhibit the temperature rise in usual liquids in the ultrasonic field, although a slight temperature rise originating in the surface layer is measured in viscous liquids such as castor oil. On the other hand, in the case of the bone and the Indian rubber, whose sizes are over a certain dimension, the internal absorption of ultrasonic waves plays the major role of the heating ; and the surface heating or interface heating is considered only as a secondary effect. Moreover, the differences of the temperature rises in various liquids indicates that the cooling effect in the ultrasonic field depends on the viscosity. The coefficient λ describing the rate of cooling will lead to the following empirical formula λ∝1/(A+Blogη). The existence of bone cortex and muscles is not so essential as to the bone heating. In the frequency range from 500 kc to 2 Mc, the tendencies of the temperature distributions are very similar in the bones whose thicknesses are about 1 cm, and the temperature rise is about 2 times higher in the front layer facing the sound beam than in the rear layer. The above measurements leads to the estimation that the ultrasonic waves are mainly absorbed near the superficial layer, and the temperature distributions are influenced by the heat conductivities.
1957-09-01