Schematic overview of the position of phantom and ultrasound probe during ultrasound image acquisition.

Schematic overview of the position of phantom and ultrasound probe during ultrasound image acquisition. Left. Position to obtain long axis images. The long axis of the probe (LA probe) is parallel to the long axis of the calcium (LA calcium). The phantom moves in direction along the short axis of the probe (SA probe). A = agar phantom with 5 increasing amounts of calcium, B = ultrasound probe mounted on support stand. Right. Position to obtain short axis images. The long axis of the probe (LA probe) is perpendicular to the long axis of the calcium (LA calcium). The phantom moves in direction along the short axis of the probe (SA probe). A = agar phantom with 5 increasing amounts of calcium, B = ultrasound probe mounted on support stand.