According to Daily Mail, a twin leans over and kisses the cheek of her sister in a rare picture captured by a modern medical imaging technique known as 3D Ultrasound. The technique was developed at Duke University, one of world's leading centers in the area of modern medical imaging, in 1987. Traditional ultrasound imaging produces 2D images at a given depth, while 3D sonography produces images at different depths. Streaming 3D images into live video is called 4D ultrasound.
A real image (perceptible by humans) is formed by reflection of visible light off an object. However, modern medical imaging uses reflections and resonances of other sources such as X-rays (CT-scan), RF pulses (MRI), wideband infrared lights (OCT), acoustic waves (Ultrasound), and radioactive isotopes (PET) along with complex mathematical formulae to post process the measured reflections.
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Picture courtesy of Wikipedia
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