CT Scan Guide: What to Expect, How to Prepare & Understanding Results

A CT scan (Computed Tomography), also called a CAT scan, is a painless diagnostic imaging test that combines X-ray images taken from multiple angles to create detailed cross-sectional views of your body. Think of it like looking at a loaf of bread by slicing it—it allows your doctor to see inside your body layer by layer.

Unlike a standard X-ray that produces a flat, 2D image, a CT scan creates detailed 3D images that show:

• ** Bones and joints in remarkable detail**
• ** Organs and soft tissues**
• ** Blood vessels**
• ** Muscles and fat**

This advanced imaging technology helps doctors diagnose and monitor a wide range of conditions with unprecedented accuracy.

Your healthcare provider may recommend a CT scan to:

Diagnose Conditions

• Internal injuries from accidents or falls
• Infections and inflammation throughout the body
• Tumors and cysts in various organs
• Bone fractures that may not appear on regular X-rays
• Blood vessel abnormalities like aneurysms or blockages
• Organ problems in the liver, kidneys, pancreas, spleen, and more

Guide Medical Procedures

• Biopsies to sample tissue for testing
• Radiation therapy planning for cancer treatment
• Surgical planning before operations
• Drainage procedures of fluid collections

Monitor Treatment

• Cancer treatment response to see if tumors are shrinking
• Infection improvement with antibiotics
• Healing progress after injuries or surgery
• Disease progression in chronic conditions

Emergency Situations

• Trauma from car accidents or falls
• Stroke to quickly identify bleeding or blockages
• Severe abdominal pain to diagnose appendicitis or kidney stones
• Chest pain to rule out pulmonary embolisms or aortic dissections

Understanding what will happen can significantly reduce anxiety and help you feel more prepared.

Before the Scan

Arrival and Check-in:

• Arrive 15-30 minutes early for registration
• Bring your ID, insurance card, and referral form
• You may need to change into a hospital gown
• Remove all metal objects (jewelry, watches, hairpins, zippers)
• Tell the technologist if you're pregnant or might be pregnant

Contrast Preparation (if needed):

• Some CT scans use contrast dye to enhance image clarity
• Oral contrast: You'll drink a liquid 1-2 hours before the scan
• IV contrast: A nurse will insert an IV line in your arm or hand
• The contrast may make you feel warm or flushed briefly
• You might notice a metallic taste in your mouth

During the Scan

Positioning:

• The technologist will help you lie on the scanning table
• You'll lie on your back, stomach, or side depending on the body part
• Pillows, straps, or foam blocks may help you stay in the correct position
• The technologist will leave the room but can see and hear you at all times
• You can communicate through an intercom system

The Scanning Process:

• The table will slowly slide into the CT scanner
• The scanner is shaped like a large donut with an opening in the center
• You will NOT be completely enclosed like in an MRI
• You'll need to stay very still during the scan
• The machine may rotate around you during the scan
• Breathing instructions: You may be asked to hold your breath for short periods (typically 5-20 seconds)
• The scanner makes whirring and clicking noises during the scan
• Most CT scans take 5-30 minutes, though the actual scanning is often just a few minutes

What You'll Feel:

• The scan itself is completely painless
• If you receive IV contrast, you may feel:
  • A warm sensation spreading through your body
  • A metallic taste in your mouth
  • A brief urge to urinate
• These sensations pass within a minute or two

After the Scan

Immediate Post-Scan:

• The table will slide out of the scanner
• The technologist will help you off the table
• You can usually return to normal activities immediately
• If you received contrast, you'll be encouraged to drink extra water
• The IV will be removed (if used)

If You Received Contrast:

• Drink 6-8 glasses of water over the next 24 hours to help flush the contrast from your body
• Watch for any allergic reactions (rare but possible)
• Call your doctor if you experience:
  • Difficulty breathing
  • Swelling of the throat or face
  • Severe itching or hives
  • Nausea or vomiting

Proper preparation ensures the best possible images and a smooth experience.

General Preparation

What to Wear:

• Wear comfortable, loose-fitting clothing without metal (zippers, buttons, snaps)
• You may be asked to change into a hospital gown
• Remove all jewelry, piercings, and metal hair accessories
• Remove hearing aids, glasses, and removable dental work if they're in the scanning area

What to Bring:

• Photo ID and insurance card
• Doctor's referral or prescription for the CT scan
• List of current medications and supplements
• Information about any allergies, especially to contrast dye or iodine
• Previous imaging results (if requested by your doctor)

Medications:

• Take your regular medications unless told otherwise
• Bring a list of your medications to share with the imaging staff
• If you have diabetes, ask about special instructions

Special Preparation for Contrast CT Scans

With IV Contrast:

• Hydrate well in the days before your scan
• Fast for 2-4 hours before the appointment (water is usually okay)
• Tell your doctor if you have:
  • Kidney problems or kidney disease
  • Diabetes
  • Multiple myeloma
  • Allergies to contrast dye, iodine, or shellfish
• Blood tests may be needed beforehand to check kidney function

With Oral Contrast:

• You may need to fast for 4-6 hours before drinking the contrast
• Plan to arrive 1-2 hours early to drink the contrast solution
• The oral contrast needs time to coat your digestive tract
• The contrast may cause mild diarrhea afterward

Special Considerations

Pregnancy and Breastfeeding:

• Tell your doctor if you're pregnant or might be pregnant
• CT scans use radiation, which may harm a developing fetus
• If breastfeeding, ask about waiting to breastfeed after contrast administration
• You may be able to pump breast milk before the scan and use it for 24 hours after contrast

Children:

• Pediatric CT scans use lower radiation doses
• Children may need sedation to stay still
• Bring comfort items and distractions
• Practice lying still at home before the appointment

Claustrophobia and Anxiety:

• CT scanners are much less confining than MRI machines
• You can see your surroundings and are not fully enclosed
• If you're anxious, tell the technologist—they can help
• Bring a support person if allowed by the facility

Mobility Issues:

• The imaging center has equipment to help transfer patients
• Call ahead if you need assistance
• Some facilities have tables that accommodate higher weight limits

Getting your results can feel stressful. Here's what to expect and what the terminology means.

Who Reads Your CT Scan?

A radiologist—a medical doctor specially trained in interpreting medical images—will carefully analyze your CT scan images and prepare a detailed report for your referring doctor.

When Will You Get Results?

Turnaround times vary:

• Emergency scans: Within minutes to an hour
• Routine scans: Typically 24-48 hours
• Complex cases: Sometimes 3-5 days if special consultation is needed

Your referring doctor will contact you to discuss the results and next steps.

Understanding Your Radiology Report

Your report will contain several sections:

Patient Information:

• Your name, age, and the date of the exam
• The reason for the scan (what your doctor is looking for)
• The type of CT scan performed

Technique Description:

• Technical details about how the scan was performed
• Whether contrast was used
• The specific body parts imaged

Findings:

• Detailed description of what the radiologist sees
• Measurements of any abnormalities found
• Comparison to prior scans (if available)

Impression/Conclusion:

• The radiologist's interpretation of the findings
• A summary of what's most important
• Recommendations for follow-up if needed

Common Terminology in CT Reports

Reassuring Terms:

• Normal/Unremarkable: No abnormalities found—this is good news!
• No acute abnormalities: No new or concerning findings
• Stable: No change from previous scans (often good)
• Benign: Non-cancerous, not concerning
• Physiologic: Normal findings for your age and body

Terms That May Need Follow-up:

• Inconclusive: Unable to make a definitive diagnosis—more tests may be needed
• Indeterminate: Unclear findings—additional imaging or monitoring may be recommended
• Recommend follow-up: The radiologist suggests repeat imaging to monitor something over time
• Clinical correlation recommended: Findings need to be considered along with your symptoms and exam

Terms That May Indicate Concern:

• New/enlarging: Something has appeared or grown since prior scans
• Suspicious: Findings that could represent serious conditions like cancer
• Pathologic: Abnormal findings that may indicate disease

What Happens After You Get Results?

Your referring doctor will:

1. Explain the findings in plain language
2. Discuss what the results mean for your health
3. Recommend next steps:
   • No further action needed (good news!)
   • Additional imaging for more detail
   • Referral to a specialist
   • Treatment options if a problem is found
   • Monitoring with repeat CT scans

Questions to Ask Your Doctor:

• What do these findings mean for my health?
• Are these findings common or rare?
• Is this something to be worried about?
• Do I need any additional tests?
• What treatment options are available?
• When should I have another CT scan to monitor this?

Understanding the risks can help you make informed decisions about your healthcare.

Radiation Exposure

CT scans use X-ray radiation, which is a known carcinogen at high doses. However, the medical benefit of an accurate diagnosis generally outweighs the small risk.

Radiation Dose Context:

• Chest X-ray: 0.1 mSv (like 10 days of natural background radiation)
• CT head: 2 mSv (like 7 months of background radiation)
• CT abdomen/pelvis: 10 mSv (like 3 years of background radiation)
• Natural background radiation per year: 3 mSv

Important Safety Points:

• Modern CT scanners use the lowest radiation dose possible
• Radiologists use "ALARA" principles (As Low As Reasonably Achievable)
• Your risk from a single CT scan is very small
• Radiation risk accumulates over a lifetime—your doctor tracks your exposure
• The benefit of accurate diagnosis typically outweighs the small risk

Special Considerations:

• Pregnancy: CT is generally avoided unless essential
• Children: More sensitive to radiation, but pediatric protocols use lower doses
• Frequent CT scans: Your doctor may consider alternative imaging without radiation when appropriate

Contrast Material Risks

Some CT scans use contrast dye (iodine-based for CT) to enhance image clarity.

Mild reactions (affect less than 1% of patients):

• Nausea
• Itching
• Hives
• Headache

Severe allergic reactions (very rare, less than 0.1%):

• Difficulty breathing
• Swelling of the throat or face
• Severe hives
• Anaphylaxis

Risk Reduction:

• Tell your doctor about any allergies, especially to contrast dye, iodine, or shellfish
• Premedication with antihistamines and steroids may be given if you have a known allergy
• Kidney function is tested before contrast if you have risk factors
• Modern contrast dyes have fewer side effects than older formulations

Other Risks and Considerations

False Positives and False Negatives:

• No test is perfect—CT scans may miss things (false negative) or find things that turn out to be nothing (false positive)
• Abnormal findings may need additional testing to clarify

Incidental Findings:

• CT scans sometimes find unexpected abnormalities unrelated to the reason for the scan
• These may need further evaluation, which can cause anxiety and additional testing

Claustrophobia:

• CT scanners are much less confining than MRI machines
• You are not fully enclosed
• If you're anxious, tell the technologist—they can help

Different CT scans are used for different purposes and body parts.

By Body Part

CT of the Head/Brain:

• Diagnose strokes, bleeding, tumors
• Evaluate head injuries
• Find causes of headaches or vision problems

CT of the Chest:

• Evaluate lung infections or cancer
• Find pulmonary embolisms
• Assess heart and blood vessel problems

CT of the Abdomen/Pelvis:

• Diagnose appendicitis, kidney stones, tumors
• Evaluate organ diseases (liver, spleen, kidneys)
• Find causes of abdominal pain

CT of the Spine/Bones:

• Evaluate fractures
• Assess arthritis and joint problems
• Guide spinal injections or surgeries

By Special Technique

CT Angiography (CTA):

• Uses contrast to visualize blood vessels
• Diagnose aneurysms, blockages, vessel malformations
• Evaluate blood flow throughout the body

CT Enterography:

• Specialized imaging of the small intestine
• Diagnose Crohn's disease and other bowel problems
• Requires oral contrast and sometimes IV contrast

CT Urography:

• Detailed imaging of the kidneys, ureters, and bladder
• Evaluates kidney stones, tumors, and urinary tract problems
• Requires both oral and IV contrast

Cardiac CT (Coronary CTA):

• Visualizes the coronary arteries
• Assesses for plaque and blockages
• Used to diagnose heart disease without invasive procedures

CT-Guided Biopsy:

• Real-time CT imaging guides needle placement
• Used to obtain tissue samples for testing
• Allows precise targeting of abnormalities

Dual-Energy CT:

• Advanced technique using two different X-ray energies
• Provides more detailed information about tissue composition
• Can sometimes distinguish between different types of stones or tumors

Your doctor may recommend a CT scan over other imaging for several reasons:

CT vs. Standard X-Ray

CT advantages:

• Much more detailed images
• Can see soft tissues and organs, not just bones
• Can create 3D reconstructions
• Better for complex problems

X-ray advantages:

• Lower radiation dose
• Faster
• Less expensive
• More widely available

CT vs. MRI

CT advantages:

• Faster (minutes vs. 30-60 minutes)
• Less expensive
• Better for seeing bone detail
• Better for emergency situations
• Pacemakers and most implants are safe

MRI advantages:

• No radiation
• Better for soft tissue contrast (especially brain, spinal cord, joints)
• Better for certain organs (liver, pancreas, reproductive organs)
• No contrast needed for many studies

CT vs. Ultrasound

CT advantages:

• More detailed images
• Can see through bone and gas
• Not operator-dependent
• Better for larger body areas

Ultrasound advantages:

• No radiation
• No contrast needed
• Real-time imaging
• Less expensive
• Better for pregnancy and some pediatric applications

CT vs. PET Scan

CT advantages:

• Shows detailed anatomy
• Faster and more widely available
• Lower cost

PET advantages:

• Shows metabolic activity (cellular function)
• Better for detecting cancer spread
• Often combined with CT for both anatomy and function

Cost factors vary widely:

Without insurance:

• Range: $300-$6,000+ depending on body part, contrast use, and facility
• Hospital-based imaging is typically more expensive than standalone centers

With insurance:

• Most insurance plans cover medically necessary CT scans
• You may have a copay, coinsurance, or deductible
• Pre-authorization may be required
• Call your insurance company to understand your coverage

Cost-Saving Tips:

• Ask about the cost beforehand
• Compare prices at different facilities if possible
• Ensure the test is medically necessary
• Ask if a lower-cost alternative (like ultrasound) might be appropriate

Does a CT scan hurt?

No, CT scans are painless. You may experience discomfort from lying still on a hard table or from the IV insertion if contrast is used.

How long does a CT scan take?

Most CT scans take 5-30 minutes total, including positioning. The actual scanning is often just a few minutes.

Will I be claustrophobic?

CT scanners are much less confining than MRI machines. You're not fully enclosed and can see your surroundings. Most people with claustrophobia tolerate CT scans without difficulty.

Can I drive after a CT scan?

Yes, unless you received sedation. Most people drive themselves home after a CT scan.

Can I eat and drink before my CT scan?

It depends on the type of scan. Some require fasting, especially if contrast will be used. Follow your specific preparation instructions carefully.

What if I'm allergic to contrast dye?

Tell your doctor! They can use a different type of contrast, give you premedication, or choose a different imaging test.

How much radiation am I exposed to?

The amount varies by the type of scan but is roughly equivalent to a few months to a few years of natural background radiation. The medical benefit typically outweighs the small risk.

When will I get my results?

Most results are available within 24-48 hours. Emergency scans are read much faster. Your doctor will contact you to discuss the findings.

Can I breastfeed after a CT scan with contrast?

Ask your doctor. You may need to wait 24 hours and pump breast milk during that time to give the contrast time to leave your body.

What if I'm pregnant?

Tell your doctor. CT is generally avoided during pregnancy unless absolutely necessary due to radiation exposure to the fetus.

Why do I need to drink contrast before my scan?

Oral contrast coats your digestive tract so it shows up clearly on the CT images. This helps the radiologist distinguish your bowel from other structures.

Before your appointment:

• Ask questions if anything is unclear
• Follow preparation instructions carefully
• Arrange for childcare if needed
• Wear comfortable clothing

During your appointment:

• Communicate with the technologist about any discomfort
• Stay as still as possible during the scan
• Take slow, deep breaths to stay relaxed
• Remember that you can communicate through the intercom

After your appointment:

• Drink extra water if you received contrast
• Watch for any delayed reactions to contrast
• Follow up with your doctor to get your results
• Keep a copy of your report for your records

• CT scans are painless, quick, and provide detailed images of your body's internal structures
• Proper preparation—especially fasting and hydration—ensures the best results
• CT scans use more radiation than X-rays but the medical benefit typically outweighs the small risk
• Contrast dye enhances image clarity but carries a small risk of allergic reaction
• Results are usually available within 24-48 hours and will be discussed with your referring doctor
• Communication is key—tell your doctor about allergies, kidney problems, pregnancy, or concerns

Comparing Imaging Options:

• CT vs MRI: How to Choose
• CT Scan with Contrast vs Without
• Imaging Radiation Safety

CT Scan Preparation:

• How to Prepare for Specific CT Scans
• What to Eat Before a CT Scan

Understanding Results:

• Understanding Your Radiology Report
• Common CT Findings Explained

Preparing for Your CT Scan?

Download our CT Scan Preparation Checklist to help you get ready for your appointment. This printable guide covers everything you need to know and do before, during, and after your CT scan.

Download Free CT Prep Checklist

Disclaimer: This guide is for educational purposes only and does not replace professional medical advice. Always consult with your healthcare provider about which imaging tests are appropriate for your specific situation.