engleski

Testing of beam characteristics of physiotherapy ultrasound transducers by analyzing thermal images

Introduction: The clinical effects of ultrasound used for physiotherapy depend on applied intensity and time of insonation. Output intensities of 0.1– 3.0 W/cm2 are typically applied for therapeutic purposes in pulsed or continuous modes. In order to accurately measure the output characteristics of ultrasonic therapy transducers, an evaluation of effective radiating area (ERA) and beam homogeneity must be made regularly in order to prevent patient damage. Purpose: Implementation of the method based on use of thermochromic tile in clinical environment for the verification of ultrasound fields produced by transducers used for physiotherapy. Materials and methods: In this work non- standardized method developed at National Physical Laboratory (NPL) was used for quality assurance of ultrasound therapy beams. The method consists of exposing thermocromic tile to the ultrasonic beam thereby forming an thermal image of the intensity profile of transducer. The image is in turn photographed and analyzed using software developed for that purpose. Results: Several physiotherapy ultrasound transducers clinically used were tested by use of thermocromic tile in the hospital environment. Thermal images were postprocesed in order to estimate effective radiating area and beam nonuniformity ratio (BNR) for tested transducers. Conclusion: Results of our measurements have shown that thermocromic tile can be used for rapid check of ultrasound transducers in the hospital environment. Furthermore, our work has also shown that it is possible postprocess thermal images in order to calculate some beam parameters such as effective radiating area (ERA) and beam nonuniformity ratio (BNR).

ultrasound ; quality assurance ; effective radiating area ; beam nonuniformity ratio

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