Diagnostic imaging allows doctors to look inside your body for clues about any medical condition. A variety of machines and techniques can create images of the structures and activities of your organs inside your body. The type of imaging your doctor uses depends on your symptoms and the part of your body being examined.
X-rays are a type of radiation called electromagnetic waves. X-ray imaging generates pictures of your body. The images show the parts of your body in different shades of black and white. This is because different tissues absorb different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat and other soft tissues absorb less, and look gray. Air absorbs the least, so lungs look black.
The most familiar use of x-rays is checking for broken bones, but x-rays are also used in other ways. For example, chest x-rays can spot pneumonia and other respiratory diseases. Mammograms use x-rays to look for breast cancer.
When you have an x-ray, you may wear a lead apron to protect certain parts of your body. The amount of radiation you get from an x-ray is small. For example, a chest x-ray gives out a radiation dose similar to the amount of radiation you’re naturally exposed to from the environment over 10 days.
Ultrasound uses high-frequency sound waves to look at organs and structures inside the body. Health care professionals use it to view the heart, blood vessels, kidneys, liver, and other organs. During pregnancy, doctors use ultrasound to view the fetus. Unlike x-rays, ultrasound does not expose you to radiation.
During an ultrasound test, you lie on a table. A special technician or doctor moves a device called a transducer over the part of your body. The transducer sends out sound waves, which bounce off the tissues inside your body. The transducer also captures the waves that bounce back. The ultrasound machine creates images from the sound waves.