In sonography (ultrasound imaging), inaudible high frequency of sound waves in the range of 1−5MHz are used. Related Theory Sonography is a medical imaging technique that uses high-frequency sound waves to produce images of internal body structures. It is also known as ultrasound. After the X-ray test, ultrasound is the most used diagnostic imaging technique. It uses a device called a transducer to send out ultrasound waves and listen for the echo. A computer translates the ultrasound waves into an image. A trained technician can see, measure, and identify structures in the image.