Royalty free and rights managed images relating to the medical use of ultrasound (ultrasonography). This non-invasive diagnostic technique uses the reflected echoes of high-frequency sound waves to image internal body tissues. It is routinely used in pregnancy to assess the health of the developing foetus. Specialised versions include echocardiography (ultrasound used to examine the heart) and Doppler ultrasound (used to examine blood flow). Also shown here are eye, liver, thyroid, pancreas, prostate and knee examinations. Photographs and pictures include doctors and nurses scanning patients using transducers and other ultrasound equipment.