Survey of use and performance of ultrasonic therapy equipment in Pinellas County, Florida

Evaluation of therapeutic ultrasound equipment performance

The therapeutic ultrasound (US) is one of the resources mostly used by physiotherapists; however the use of uncalibrated equipment results in inefficient or even harmful therapies to the patient. In this direction, the objective of this study was to evaluate the performance and the procedures of utilization and maintenance of US in use in clinics and Physical-therapy offices. A questionnaire with questions related to the procedures applied in service during the use of therapeutic ultrasound was applied to physiotherapists. The performance of 31 equipment of 6 different brands and 13 different models was evaluated according to the IEC 61689 norm. The parameters measured were: acoustic power; effective radiating area (AER); non-uniformity ratio of the beam (RBN); maximum effective intensity; acoustic frequency of operation, modulation factor and wave form on pulsate mode. As for the questionnaires, it was evident that the professionals are not concerned about the calibration of the equipment. The results demonstrated that only 32.3% of the equipment were in accordance with the norms for the variables power and effective radiation area. The frequency analysis indicated that 20% of the 3MHz transducers and 12.5% of the 1MHz contemplated the norms. In the pulsate mode, 12.7% presented relation rest/duration inside allowed limits. A great variation of the ultrasonic field was observed on the obtained images, which presented beams not centered, sometimes with bifurcation of its apex. The results allow concluding that, although used in therapeutic sessions with the population, none of the equipment presents all the analyzed variables inside technical norms.

The effect of back reflections on the acoustic power delivered by physiotherapy ultrasound machines

Physiotherapy ultrasound is used widely for the treatment of soft tissue injuries. The ultrasonic treatment heads are all highly resonant devices and may therefore be sensitive to the levels of acoustic back reflection that they experience. However, the extent to which reflections affect acoustic power during clinical use has not been reported in the literature and is not addressed in current technical standards. This study investigated the effect of physiological levels of acoustic reflection on 29 physiotherapy treatment heads from a total of 21 machines and 6 manufacturers. A range of membranes were constructed and used to mimic the levels of acoustic reflections that occur during treatment. The results obtained showed that almost half of the heads tested (45%) had deviations in acoustic power of more than 15% compared with free-field measurements. Four heads (17%) had deviations in power of more than 25%. We recommend that the susceptibility of physiotherapy ultrasound machines to acoustic reflections be addressed in the relevant technical standards. Also, it is appropriate for tests to be carried out during design and manufacture, and by the purchaser during their acceptance testing.

Calibration and measurement issues for therapeutic ultrasound

This review paper examines some of the issues relating to calibration and measurement of therapeutic medical ultrasonic equipment (MUE). This is not intended to be an all-encompassing review of all aspects of characterising therapeutic ultrasound. Instead it concentrates on issues related to the acoustic output of two applications: physiotherapy and high intensity focused ultrasound surgery (HIFUS or HIFU; also referred to as high intensity therapeutic ultrasound, HITU). Physiotherapy has a well-established standards infrastructure for calibration: the requirements are small in number and well-defined. The issue for physiotherapy is not so much 'How to calibrate?' but rather, 'How to ensure that equipment IS calibrated?' The situation in the much newer area of HIFU is very different: the first steps towards writing standards are just starting and even the very basic questions of what to measure and with what type of sensor are open for debate. Readers whose main interest is in other ultrasound therapies will find ideas of relevance to their own specialty.

Ultrasound usage and dosage in sports physiotherapy

Ultrasound (US) therapy is the most widely available and frequently used electrophysical agent in physiotherapy. Despite this, there is minimal scientific evidence supporting its use. This raises the question of how is US being used in clinical practice? With a questionnaire, this study investigated US usage and dosage in sports physiotherapy. The results confirm the wide availability and frequent use of US. Applications were found to cover a wide range of clinical scenarios, during which therapists use a range of dosages. Two trends in dosage were evident and relate to the treatment of either acute or chronic conditions. Although rationale exists for these dosages, clinical evidence is currently lacking. Reasons for this lack of evidence are discussed. The results of this study provide a profile of US usage and dosage in sports physiotherapy and highlight the need for further research into its effects.

Evaluation of the acoustic intensity of new ultrasound therapy equipment

International safety standards recommend a limit below 30% variation in acoustic intensity for ultrasound therapy (UST) equipment. In view of this question, the purpose of this work was to evaluate the intensity of new UST equipment in the Brazilian market. An evaluation was performed of eight models manufactured by six different national manufacturers; under continuous and pulsed conditions, at frequencies of 1.0-3.0 MHz, for a total of 48 items of equipment. The intensities were analysed according to the technical standards IEC 601-2-5, in the range 0.01-3.0 Wcm(-2), using a radiation pressure scale UPM-DT-10 (Ohmic Instruments), previously calibrated. The results demonstrated that the models Sonacel, Sonacel plus, Sonacel III, Avatar I, and Sonamed I, although they were new (unused) presented calibration errors of over 30% in more than one intensity checked, and the models SONOPULSE, PRO-SEVEN and SONOMASTER ST. are within the standards proposed. The results show that industry must improve quality control on their production lines, as well as that there is a need for a supervising body at national level. Published by Elsevier Science B.V.

Therapeutic modalities in hand surgery

Therapeutic modalities are useful adjuncts in the rehabilitation of many patients commonly seen by hand surgeons. Therapeutic heat, cold, electrical stimulation, and laser and magnetic field treatments are evaluated for their respective mechanisms of action, indications, contraindications, and clinical results. The majority of therapeutic modalities have been extensively investigated and relevant basic science and randomized well-controlled clinical studies addressing the efficacy of therapeutic modalities are emphasized.

A new method for measuring the effective radiating area of physiotherapy treatment heads

This paper describes the investigation and validation of a new method for measuring the effective radiating area (AER) of physiotherapy ultrasound treatment heads. The method is based on the use of a conventional radiation force balance, but employs special attenuating apertures that are used to selectively mask off different areas of the treatment head. The resultant reduction in the radiating surface is accompanied by a decrease in output power that is measured using the force balance. The AER of the treatment head is derived from an analysis of the measurements, which essentially involves initially evaluating the minimum area through which 75% of the acoustic power is transmitted. AER values derived using the new method are presented for 17 treatment heads representative of the range of physiotherapy systems commonly used in clinical practice. These are compared to reference values derived using hydrophone scanning, according to the recently published International Standard, IEC 1689. Typical levels of agreement between values of AER derived using the two techniques are +/- 11%. The potential of the method as a rapid, relatively low-cost, means of measuring treatment head AER, applicable in both manufacturing and hospital environments, is assessed.

The performance of ultrasound physiotherapy machines in Lothian Region, Scotland, 1992

Eighty-five ultrasound therapy machines in use in Lothian Region, Scotland were tested for performance and their recalibration was expedited where necessary. The performance characteristics reported are the temporal average acoustic output power, the treatment frequency, pulse timing and treatment timer accuracy. Consideration is also given to the performance of the wide dynamic range radiation force balance that was used to make acoustic power measurements. Of the machines tested, 69% had power outputs that differed by more than 30% from the expected values. The results of power measurements are analysed according to continuous and pulsed output, single and dual frequency treatment heads and year of manufacture. Therapy machines more than 10-12 years old and modern dual frequency treatment heads performed particularly badly. This study suggests that the performance of ultrasound therapy machines has improved little in the last 20 years despite the introduction of IEC 601-2-5 in 1984.

Devices for the diagnosis and treatment of temporomandibular disorders. Part III: Thermography, ultrasound, electrical stimulation, and electromyographic biofeedback

This last article in the three-part series on devices for the diagnosis and treatment of temporomandibular disorders (TMD) compared the claimed diagnostic usefulness of thermography with the present scientific evidence. In a similar manner, the therapeutic efficacy of ultrasound, electrical stimulation, and electromyographic biofeedback was also reviewed. This evaluation concluded that the application of thermography to the diagnosis of TMD is limited by variations within and among subjects and by intrinsic problems with controls of the test environment. It also concluded that evidence that therapeutic ultrasound alone is useful for the treatment of TMD is lacking, that positive clinical results of electrical stimulation may not be due to specific therapeutic effects, and that it is doubtful that the use of electrical stimulation devices can produce a position of the mandible that has any diagnostic or therapeutic significance. There is evidence, however, that relaxation training, assisted by EMG biofeedback, can reduce daytime muscle activity.