Nelson, Paul A.

As early as 1932 Freundlich, Sollner, and Rogowski proposed the use of ultrasonics in medicine for diathermy. They were able to demonstrate that bone marrow could be heated. The results of their study indicated clearly that further experiments needed to be done to extend these preliminary observations. We have completed a study of the temperatures produced by ultrasonics in bone marrow, bone, and adjacent tissues in the extremities of the dog. The frequency used in these studies was 800 kilocycles per second. The maximum output of the ultrasonic generator was approximately 15 watts. High temperatures can be produced in bone marrow and bone with relatively low outputs of ultrasonic energy. The adjacent tissues are heated only moderately. Ultrasonics must be used with caution in the proximity of bones because the temperatures produced in bone and bone marrow may rise to dangerous levels within a very few minutes.