In a similar way, the complex ultrasound scanning apparatus draws a picture of whatever organ the sound waves are bouncing off. This picture can reveal a lot of information.
Many people are aware of ultrasound as a safe way to examine a fetus to search for abnormalities. But it is also useful for detecting possibly malignant masses or lumps without the need for x-rays.
Ultrasound is used to examine the neck for tumors of the thyroid gland or of the parathyroids. It is the standard method to diagnose gallstones, since the sound waves bounce quite nicely off the stones. And it is often used in the pelvis to study possible enlargement of the prostate or an ovary. Benign ovarian cysts are common, and other ways of examining this part of the body are not very precise. It has also recently been adapted to help stage rectal and esophageal cancers.
