Ultrasonography uses high frequency sound waves to create images. The sound waves are directed into the body and are reflected back to the ultrasound transducer. The reflected sound waves provide information about the depth, type of tissue, and tissue interfaces. This information is converted into grayscale images.

Unlike radiography, fluoroscopy and CT, ultrasound does not use ionizing radiation, so is low risk to the patient. It is non-invasive, relatively inexpensive, and allows one to perform "real-time" or "live" imaging and to observe motion.

You can view individual sections of this module using the selections on the right.



1. How images are obtained

2. Factors affecting appearance

3. What anatomical structures are well seen

4. Indications for use