Ultrasound imaging, also called ultrasound scanning or sonography is a method of obtaining images from inside the human body through the use of high frequency sound waves. The sound waves' echoes are recorded and displayed as a real-time visual image. No ionizing radiation is involved in ultrasound imaging. Because ultrasound images are captured in real time, they can show movement of internal tissues and organs and enable physicians to see blood flow. This can help to diagnose a variety of conditions and to assess damage caused by illness.