title: A thermal beam-shape phantom for ultrasound physiotherapy transducers.
abstract: Acoustic beam nonuniformities are not uncommon in physiotherapy ultrasound equipment and can lead to errors in delivered dose. A relatively simple thermal technique is described for mapping the intensity distribution in physiotherapy ultrasound beams that could be used for routine QA checks. The technique uses a thermochromic material sandwiched between layers that absorb ultrasound. The structure is used in a water bath to intersect the ultrasound beam. Thermal models predict that, with suitable absorbing materials and careful control of the surface temperature of the layers, sufficient spatial resolution and sensitivity can be achieved to show the intensity distribution in physiotherapy ultrasound beams. Thermal images of sections through physiotherapy ultrasound beams using this method correlate well with corresponding intensity maps generated by planar scanning with a hydrophone.
authors.affiliation: Medical Physics Department, Leicester Royal Infirmary NHS Trust, UK.
authors.forename: K
authors.initials: K
authors.lastname: Martin
authors.forename: R
authors.initials: R
authors.lastname: Fernandez
mesh_terms: D006358:Hot Temperature; D006801:Humans; D019047:Phantoms, Imaging; D026741:Physical Therapy Modalities / Q000295:instrumentation; D014159:Transducers; D014464:Ultrasonic Therapy / Q000295:instrumentation* / Q000592:standards