Approaching the possible origin of non-ideal radiations in ultrasonic thermal therapy coining from the applicators housing and modifying the expected radiation patterns

The classical therapeutic applications based on ultrasound is one of the most widely and frequently used technique to treat people with pain, musculoskeletal injuries, and soft-tissue lesions. Despite the research already made on ultrasonic therapy devices, it is well known that an explanation of the real behavior of the radiation patterns in commercial physiotherapy applicators hardly has been investigated. Thus, it is of interest to make new extensive evaluations of these aspects to facilitate proposals of thermal treatments over delimitated areas with enough precision and patient safety. This work presents a comparative experimental evaluation of the acoustic patterns produced by two ultrasonic therapy applicators, of the same series and model in a commercial company. Some anomalous unexpected radiations observed in the near zones of both devices have been analyzed, showing unhomogeneities of very distinct magnitude in each one; their possible origins are analyzed. An authors´ modeling of the complex radiation in such therapeutic applicators is improved to numerically simulate these radiated CW fields. Numerical results approach in part experimental radiated patterns, which would explain a possible origin of the spurious radiations and their influence on the effectively measured ultrasonic fields.