What is computed tomography (CT scan)?
A CT scan uses a large machine shaped like a large donut to take x-rays from many angles. A computer then takes the x-rays and creates many detailed pictures of the inside of your body. Each picture looks like a slice taken from one part of your body. The computer can also create a 3-D image of the inside of your body.
CT scans are good at showing details of organs and other tissues in your brain, head, neck, chest, and belly
Why would I need a CT scan?
Doctors use CT scans for many kinds of problems, including:
Problems in your brain and spinal cord, such as bleeding, tumors, or birth defects
Problems inside your belly, such as blocked intestines and tumors or infection in your kidneys, liver, or lungs
Problems in female reproductive organs, such as tumors in the uterus or ovaries
Abnormal blood vessels of your heart or aorta (a large artery connected to your heart)
Broken bones, particularly in your hip, back (spine), and pelvis
Torn muscles and ligaments
What happens during a CT scan?
Before the scan
Often, you don't need to do anything prior to the CT scan. Sometimes, doctors will give you a liquid (called a contrast agent) through a vein, to swallow, or sometimes inserted in your rear end. The contrast agent makes a certain part of your body show up on the scan more clearly.
During the scan
You’ll lie still as the table moves through a large scanner shaped like a donut
You may need to hold your breath briefly so that the images aren't blurred
You may hear whirring sounds as the scanner moves to take x-rays from many angles
A CT scan usually lasts for a few seconds up to a few minutes
After the scan
You can go back to your usual activities.
What are the risks of having a CT scan?
Radiation
A CT scan exposes you to more radiation than a plain x-ray Plain X-Rays A plain x-ray is an imaging test that takes a picture of the inside of your body. It uses a low dose of x-ray radiation. X-rays show body parts according to how dense (solid) they are. Doctors... read more 
, like one of your chest. Doctors try to limit the total amount of radiation you're exposed to over your lifetime. Too much radiation can raise your chance of getting cancer.
For pregnant women and children, doctors try to use other tests unless CT is the best way to find a dangerous health problem.
Other problems
Some people feel uncomfortable when the contrast agent is injected
Some people have an allergic reaction to the contrast agent (such as sneezing, a rash, or trouble breathing)
If you have kidney problems (such as kidney failure Acute Kidney Failure Your kidneys are 2 bean-shaped organs that produce urine. They’re about the size of your fist and are in the back of your abdomen, near your spine. Kidneys balance your body’s water and mineral... read more ), the contrast agent can make your problems worse
