Key Point: More than one-third of the therapeutic ultrasound machines tested were operating outside of limits. (Prenatal viewing is with diagnostic, not therapeutic, ultrasound machines)

A Calibration Study of Therapeutic Ultrasound Units


Paul A Artho, Jason G Thyne, Barry P Warring, Chris D Willis, Jean-Michel BrismeĀ“ e, Neal S Latman. Jounal of Physical Therapy . Volume 82 . Number 3 . March 2002


We believe that clinicians should be aware that the intensity displayed on ultrasound units is not always a direct indication of the actual output being emitted. In addition, although most new ultrasound units have digital timers, we strongly recommend when purchasing used equipment that the machines have digital timers. According to our data, improvement has been made regarding the accuracy of therapeutic ultrasound when compared with past research findings. This improvement may be due to several factors. One factor may have been an increase in awareness by ultrasound technicians and manufacturers of the importance of machine accuracy. The differences may also have been attributable to testing machines in a different region than previous studies. However, more than one third of machines tested in this study were outside the standard for power output, as were almost one fourth of mechanical timers. Thus, further improvement in the accuracy of ultrasound machine calibration is needed. Clinicians should not hesitate to request that ultrasound machines be checked for power output and timer accuracy, which would benefit the safety of the patient and decrease the liability of the institution. Proper calibration would help ensure that patients receive a more accurate ultrasound dosage and, therefore, safe and appropriate treatment.