• Ultrasound is sound having a frequency above the audible range (> 20 kHz).
• Frequencies range of million of cycles per second.
• Ultrasound is used in medicine for diagnostic purposes.
• Diagnostic ultrasound uses the principle that ultrasound is reflected by an interface between media of different acoustic impedances.
• The image is produced by the display of the echoes returning to the transducer. The image is composed of pixels varying in light intensity, which depends on the intensity of the reflected echo.
• The reflection depends on the density of the media and subsequently various structures produce specific images depending on the acoustic mismatching of the reflected sound waves.
• In musculoskeletal imaging a linear probe is used to assess structures.

Patient ultrasound positioning