What to Expect at Your CT Scan Appointment

What happens during a CT scan

A CT scan (computed tomography) is a fast imaging test that takes detailed cross-section pictures of the inside of your body using X-rays and a computer. You lie still on a table that slides into a large, donut-shaped machine. The machine rotates around you, taking many images from different angles. The whole scan usually takes 10 to 30 seconds, though you may be in the room for 15 to 30 minutes total while the technician positions you and checks the images.

Unlike an MRI, a CT scan is quick and makes no noise. You won't feel anything during the scan itself. If your doctor ordered a contrast CT, you'll drink a liquid or receive an injection beforehand to make certain parts of your body show up more clearly on the images. The contrast is usually iodine-based and passes through your system within a day or two.

The radiologist (a doctor who specializes in imaging) reviews the images after your appointment and sends a report to your doctor. Your doctor will discuss the results with you at a follow-up visit or phone call, usually within a few days.

Key Takeaways

• Arrive 10 to 15 minutes early with your insurance card and photo ID, and bring any previous imaging from other facilities if your doctor didn't already request them.
• Wear comfortable, loose clothing without metal (no zippers, snaps, or underwire bras), and remove jewelry, glasses, and hearing aids before the scan.
• If you're receiving contrast, tell the technician about any allergies, kidney problems, or medications like metformin before the scan begins.
• You can eat and drink normally before most CT scans, but contrast scans often require you to fast for a few hours — your appointment letter will specify what applies to you.
• The scan itself takes less than a minute, but plan for 30 to 45 minutes at the imaging center from check-in to leaving.

What to bring and wear

Bring your insurance card, photo ID, and any paperwork your doctor's office gave you. If you've had imaging done at another hospital or clinic, bring those images on a CD or USB drive if you have them — your doctor may have already requested them, but having them on hand speeds things up.

Wear loose, comfortable clothing without metal fasteners. Metal interferes with the images, so avoid underwire bras, jeans with metal zippers, and shirts with snaps or metal buttons. You can wear a t-shirt and sweatpants. Remove jewelry, watches, glasses, hearing aids, and any removable dental work before you enter the scan room. If you have a pacemaker or other implanted metal device, tell the technician immediately — some devices are safe in a CT scanner, but the technician needs to know.

If you wear a continuous glucose monitor or insulin pump, let the technician know. Most are safe during CT scans, but the technician may ask you to remove it temporarily or position it away from the scan area.

Fasting and contrast preparation

For most CT scans of the head, chest, or bones, you don't need to fast or do any special preparation. You can eat and drink normally and take your regular medications.

If your scan involves contrast — usually for abdominal or pelvic imaging — your appointment letter will tell you to fast for 4 to 6 hours beforehand. This means no food, and usually only clear liquids like water or black coffee. Fasting helps the contrast show up clearly and reduces nausea. Take your regular medications with a small sip of water unless your doctor told you otherwise.

Before a contrast scan, the technician will ask about your medical history. Tell them if you have kidney disease, diabetes, heart problems, or a history of allergic reactions — especially to iodine or shellfish. If you take metformin (a diabetes medication), you may need to stop it for 48 hours after the scan because the combination of metformin and contrast can affect your kidneys. Your doctor will have mentioned this, but confirm with the technician.

What to expect in the waiting room and scan room

You'll check in at the front desk and wait in a reception area. A technician will call you back and take you to a changing room if needed. They'll ask you to remove metal items and may have you change into a hospital gown, though many CT scans don't require this — you can stay in your regular clothes if they're metal-free.

In the scan room, the technician will position you on the table and may use pillows or straps to keep you still. They'll explain what's about to happen and tell you to hold your breath when the scan begins — this keeps your organs from moving and blurring the images. You'll hear a buzzing or whirring sound as the machine rotates. The technician watches from a control room and can see and hear you the whole time through a window and speaker.

If you're receiving contrast, the technician will insert an IV (intravenous line) in your arm before the scan. You may feel warmth, flushing, or a metallic taste in your mouth as the contrast flows in — this is normal and passes quickly. Tell the technician immediately if you feel dizzy, have trouble breathing, or develop a rash.

After your CT scan

You can return to your normal activities right away. There are no side effects from the radiation exposure at the dose used in a CT scan. If you received contrast, drink extra water for the rest of the day to help flush it from your system. You may notice the contrast in your urine — this is normal.

The radiologist will review your images and prepare a written report, usually within 24 hours. Your doctor's office will contact you with the results, or you may see them in your patient portal if your healthcare system has one. If your doctor doesn't reach out within a few days, call to ask about the results.

If the scan shows something that needs follow-up — like a second imaging test, blood work, or a specialist visit — your doctor will explain what comes next and why. Some findings are routine and don't change your care; others guide treatment decisions.

Radiation exposure and safety

A CT scan uses ionizing radiation, which is a type of energy that can damage cells in large doses. The radiation dose from one CT scan is higher than from a single X-ray, but it's still considered safe for diagnostic purposes. The benefit of the detailed images usually outweighs the small risk.

If you're pregnant or think you might be, tell your doctor and the technician before your scan. CT scans are generally avoided during pregnancy unless there's a medical reason that makes the benefit worth the risk. If you're breastfeeding and received contrast, you can continue breastfeeding — the contrast doesn't pass into breast milk in significant amounts.

If you've had multiple CT scans in a short time, mention this to your doctor. Cumulative radiation exposure over many scans can add up, and your doctor may choose a different imaging method for future tests if possible.

Common reasons for CT scans and what they show

CT scans are ordered for many reasons: to evaluate chest pain or shortness of breath, check for broken bones or internal injuries after trauma, look for tumors or masses, investigate abdominal pain, or follow up on a finding from another test. Your doctor ordered the scan because they need to see inside your body in detail to make a diagnosis or rule out serious conditions.

The images show bone, soft tissue, and organs clearly. A radiologist can spot fractures, bleeding, infections, tumors, kidney stones, appendicitis, and many other conditions. Sometimes a scan shows something unexpected that isn't related to why you came in — your doctor will discuss any incidental findings with you.

Frequently Asked Questions

Do I need someone to drive me home after a CT scan?

No. A CT scan doesn't use sedation, so you're alert and safe to drive immediately afterward. You can go back to work, run errands, or do whatever you normally do. If you received contrast, you may feel slightly tired, but this passes quickly.

What's the difference between a CT scan and an MRI?

A CT scan uses X-rays and is fast (under a minute), while an MRI uses magnetic fields and takes 30 to 60 minutes. CT is better for bone, lungs, and emergency situations. MRI is better for soft tissue like the brain, spinal cord, and joints. Your doctor chooses based on what they need to see.

Is contrast always necessary for a CT scan?

No. Many CT scans — like those for broken bones, kidney stones, or lung nodules — don't need contrast. Your doctor and the imaging center decide whether contrast will help answer the clinical question. Your appointment letter will tell you if contrast is planned.

What if I'm claustrophobic?

CT scanners are much more open than MRI machines. You're not enclosed; the table slides in and out of a large donut-shaped opening. Most people with claustrophobia find CT scans tolerable. If you're very anxious, tell your doctor beforehand — they may recommend a mild sedative or a different imaging test.

How long does it take to get results?

The radiologist usually reviews the images and writes a report within 24 hours. Your doctor's office will contact you with the results, or you may see them in your patient portal. If it's urgent — like a scan done in the emergency room — results may be available within an hour.