A CT scan uses X-rays and a computer to create detailed cross-section pictures of the body. Learn what it shows, how it works and how to prepare.
A CT (Computed Tomography) scan is an imaging test that uses X-rays and a computer to make detailed cross-section pictures of your body. It is fast, painless and very useful for finding injuries, infections, stones, tumours and bleeding.
How Does a CT Scan Work?
You lie on a table that moves through a large ring. Inside the ring, an X-ray tube rotates around you and takes many images from different angles. A computer joins them into slices, like slices of bread, and can also build 3D views. Because the slices are thin, doctors can see small details that a plain X-ray may miss. Compare them in CT scan vs X-ray.
CT scan typeCommon useUsually needs contrast?CT brainHead injury, stroke, bleedingNot alwaysHRCT chestLung disease, breathlessnessNoCT abdomen and pelvisPain, infection, tumoursOften yesCT KUBKidney and ureter stonesNoWhy Do Doctors Advise a CT Scan?
- Head injury, bleeding or stroke. See CT brain scan.
- Cough, breathlessness or lung nodules. See HRCT chest.
- Severe belly pain, infection or suspected lumps. See CT abdomen and pelvis.
- Kidney stones with sudden back pain. See CT KUB for kidney stones.
- Checking cancer spread or treatment results.
- Guiding a biopsy. See CT-guided biopsy.
How to Prepare for a CT Scan
- For scans with contrast, avoid food for 4 to 6 hours. Water is allowed.
- Tell the staff about kidney disease, diabetes, asthma or past reaction to contrast.
- Remove metal items such as chains, belts and coins.
- Tell the team if you may be pregnant.
- Bring previous scans and reports.
Read the full list in CT scan preparation.
What Happens During the Scan?
The technologist helps you lie still on the table. If contrast is needed, it is given through a vein, or sometimes as a drink. You may feel warmth for a minute. The machine moves through the ring, and you may be asked to hold your breath for a few seconds. The scan itself often takes less than 10 minutes. See CT scan procedure step by step and CT with contrast.
Is a CT Scan Safe?
A CT scan uses a small amount of radiation. The benefit of finding a serious problem early is usually much greater than the small risk. Doctors avoid repeat or unneeded scans, and use extra care for children and pregnancy. Read CT scan radiation dose and CT scan during pregnancy.
Your CT Scan Report
A radiologist reviews the images and writes a report, often within 24 hours. Ask your doctor to explain it with your symptoms and other tests. See how to read a CT scan report.
Practical Tips Before Your CT Scan
Wear a loose cotton top and pants without metal buttons or zips. If your scan is for the abdomen, avoid heavy meals on the previous night. Carry your latest blood report, especially the creatinine value if you have kidney concerns. After a contrast CT, drink 2 to 3 glasses of extra water unless your doctor has restricted fluids, as this helps your kidneys clear the dye. Call your doctor at once if you notice rash, swelling of the face or trouble breathing.
If the scan is for a child or an older adult, a family member may be allowed to stay nearby, with a lead apron, to give comfort.
Frequently Asked Questions
What is a CT scan used for?
It is used to find injuries, bleeding, infections, stones, tumours and many other problems inside the body.
Is a CT scan painful?
No. You may feel a needle prick if contrast is given, and a warm feeling for a short time.
How long does a CT scan take?
The scan takes a few minutes. The whole visit usually takes 20 to 30 minutes.
Do I need to fast for a CT scan?
Only for scans with contrast, usually for 4 to 6 hours. Your centre will tell you.
Is CT scan better than MRI?
Neither is always better. CT is faster and good for bones, lungs and emergencies, while MRI shows soft tissue better. See MRI vs CT scan.
Is a CT scan harmful?
The radiation dose is small and the test is done only when needed.
Can children have a CT scan?
Yes, when needed, with a low-dose setting. See CT scan for children.
Can contrast cause allergy?
Rarely. Tell the staff about past reactions, asthma or kidney problems before the scan.
How much does a CT scan cost?
The price depends on the body part and contrast. See CT scan cost factors in Delhi.
Book Your Test at Ganesh Diagnostic
Ganesh Diagnostic & Imaging Centre in Rohini, Delhi offers this test with trained radiology staff and clear reports. You can book an appointment online, check our branches across Delhi NCR, contact us for current rates, or explore all our services.
This article is for general information only. It does not replace advice from your doctor. Always follow your doctor's instructions for your test.
