Pionorio Omena T1, Coelho de Albuquerque Pereira W2, von Krüger MA2, Medeiros Costa R3, Lobianco de Matheo L2
1Federal University of Rio de Janeiro, Physical Therapy, Rio de Janeiro, Brazil, 2Federal University of Rio de Janeiro, Engineering Program, Rio de Janeiro, Brazil, 3Instituto Nacional do Cancer, Physical Therapy, Rio de Janeiro, Brazil
Background: During ultrasound therapy it is recommended to move the transducer at 4cm.s-1 to uniformly distribute the energy into the tissues. However, there is a lack of scientific works that justify the more efficient dosages and as well as the proper speed of application. This work studies the influence of the transducer speed in the heating pattern of an ultrasonic phantom inside a specially designed calorimeter with thermocouples.
Purpose: To compare heating patterns in a soft tissue phantom irradiated by ultrasound, applied by two physical therapists moving the transducer at different average speeds.
Methods: The soft tissue phantom was constructed based on an IEC standard (IEC 60601-2-37, 2007), and inserted in a calorimeter with type-K thermocouples to measure the temperature along the application time. The two physical therapists had at least 10 years of clinical practice. Nine thermocouples measured temperature in the calorimeter (3 at 10-mm-depth, 3 at 30-mm-depth and 3 at 50-mm depth). Before the experiment, the calorimeter stayed immersed in an ultrathermostat bath at 36°C for 30 minutes. The ultrasound protocol adopted was: 1-MHz transducer (Avatar III, KLD, São Paulo, Brazil), continuous mode, effective intensity 1.82 W.cm-2, 10 minutes. The calorimeter was positioned over an ultrasound absorbing plaque (APTflex). Each physical therapist moved the transducer manually, following the circular perimeter of the calorimeter (a PVC cylindrical structure, of internal diameter 75mm and height 50mm) during 10 minutes. The number of turns was registered to calculate the average velocity. Experiments were performed 20 times for each physical therapist. Temperature data were registered using a software on Labview®, and statistical analysis was performed.
Results: The average speeds for physical therapist A was about 3.5 times smaller than for B (2.43cm.s-1±0.15, and 7.45cm.s-1±0.23, respectively). Literature presents that, although it is recommended a speed of 4cm.s‑1, in clinical practice values of 7 to 8cm.s-1 are found. The time to reach 40°C was higher for physical therapist A (at 10mm: 381s, 30mm: 537s) than for B (at 10mm: 275s and 30mm: 405s). So it took longer for therapist A to reach the therapeutic temperature range of 40-45°C. At 50 mm no experiment reached 40°C. The increase of the temperature for physical therapist A at 10mm ranged between 4.60-5.50°C, and at 30mm, between 4.15-4.48°C. For physical therapist B the increase range at 10mm was 5.79-7.24°C, and at 30mm was 4.83-5.14°C. Statistical analysis showed that there were difference on 2, 3 and 4 thermocouples [p= 0,05], at 10 and 30mm depths.
Conclusion(s): Dynamic transducer application shows that there is statistical difference in the heating response between the two physiotherapists using the same ultrasound equipment and the same protocol, at different transducer velocities.
Implications: These results may contribute to the formulation of protocols to improve the application of this technology in treatment.
Keywords: Ultrasound, Speed, Temperature
Funding acknowledgements: CNPq, CAPES and Faperj.
Purpose: To compare heating patterns in a soft tissue phantom irradiated by ultrasound, applied by two physical therapists moving the transducer at different average speeds.
Methods: The soft tissue phantom was constructed based on an IEC standard (IEC 60601-2-37, 2007), and inserted in a calorimeter with type-K thermocouples to measure the temperature along the application time. The two physical therapists had at least 10 years of clinical practice. Nine thermocouples measured temperature in the calorimeter (3 at 10-mm-depth, 3 at 30-mm-depth and 3 at 50-mm depth). Before the experiment, the calorimeter stayed immersed in an ultrathermostat bath at 36°C for 30 minutes. The ultrasound protocol adopted was: 1-MHz transducer (Avatar III, KLD, São Paulo, Brazil), continuous mode, effective intensity 1.82 W.cm-2, 10 minutes. The calorimeter was positioned over an ultrasound absorbing plaque (APTflex). Each physical therapist moved the transducer manually, following the circular perimeter of the calorimeter (a PVC cylindrical structure, of internal diameter 75mm and height 50mm) during 10 minutes. The number of turns was registered to calculate the average velocity. Experiments were performed 20 times for each physical therapist. Temperature data were registered using a software on Labview®, and statistical analysis was performed.
Results: The average speeds for physical therapist A was about 3.5 times smaller than for B (2.43cm.s-1±0.15, and 7.45cm.s-1±0.23, respectively). Literature presents that, although it is recommended a speed of 4cm.s‑1, in clinical practice values of 7 to 8cm.s-1 are found. The time to reach 40°C was higher for physical therapist A (at 10mm: 381s, 30mm: 537s) than for B (at 10mm: 275s and 30mm: 405s). So it took longer for therapist A to reach the therapeutic temperature range of 40-45°C. At 50 mm no experiment reached 40°C. The increase of the temperature for physical therapist A at 10mm ranged between 4.60-5.50°C, and at 30mm, between 4.15-4.48°C. For physical therapist B the increase range at 10mm was 5.79-7.24°C, and at 30mm was 4.83-5.14°C. Statistical analysis showed that there were difference on 2, 3 and 4 thermocouples [p= 0,05], at 10 and 30mm depths.
Conclusion(s): Dynamic transducer application shows that there is statistical difference in the heating response between the two physiotherapists using the same ultrasound equipment and the same protocol, at different transducer velocities.
Implications: These results may contribute to the formulation of protocols to improve the application of this technology in treatment.
Keywords: Ultrasound, Speed, Temperature
Funding acknowledgements: CNPq, CAPES and Faperj.
Topic: Electrophysical & isothermal agents
Ethics approval required: No
Institution: Federal University of Rio de Janeiro
Ethics committee: Federal university of Rio de Janeiro.
Reason not required: This work is about an experimental research with equipments in a tissue mimicking material, not in animals and humans.
All authors, affiliations and abstracts have been published as submitted.
