Improvement of the precision of Quantitative Ultrasound (QUS) measurements at the calcaneus by tilting of the beam incidence angle
Résumé
QUS measurements at the calcaneus can be used for the estimation of osteoporotic fracture risk, but the use for therapy monitoring is unclear yet. One reason might be the limited precision of commercial devices. Our intent was to investigate the impact of the beam incidence angle at the calcaneus on the precision of the speed of sound (SOS). We developed a device with an array (120 elements) as receiver (d=100mm) and one single element emitter of the same size. Both are placed on opposite sides of the foot and mounted on a c-arm which can be rotated and tilted. SOS of 6 volunteers was measured three times with repositioning with our device (angles from 0° to 14°, step size 3.5°) and with the commercial device Achilles Insight. The pair of angles used by the Achilles and those yielding the highest amplitude of the first oscillation was analyzed. The precision of the Achilles was 9.4 m/s, the precision of our device at the Achilles angles was 2.9 m/s and 2.0 m/s at the individually defined angles. We achieved a better precision with our device than with the Achilles Insight, which can even be improved by measuring under the optimal tilting angles.
Domaines
Acoustique [physics.class-ph]
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