Ultrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes.Source : <a href="http://elena.aut.ac.nz/homepages/staff/Dave-Parry/basic%20physics.pptFree">http://elena.aut.ac.nz/homepages/staff/Dave-Parry/basic%20physics.pptFree</a> Hand Ultrasound Mapping - Metritrack tools for freehand ...