Step-by-step PET CT scan procedure: from the injection and resting time to the scan itself, how long it takes and what to do afterwards.
A PET CT scan has four main steps: check-in and blood sugar test, a tracer injection, a 45 to 60 minute rest, and a 20 to 30 minute scan. The whole visit takes about 2 to 3 hours, and the scan itself is painless.
Step 1: Check-In and Blood Sugar Test
You arrive after fasting. The staff checks your history, medicines, allergies and old reports. A small finger-prick test measures blood sugar, since high sugar can affect the images. Your height and weight help calculate the tracer dose. You may change into a gown and remove metal items. See PET CT preparation for the checklist.
StepWhat happensApproximate time1. Check-inForms, weight, height, blood sugar test15 to 20 minutes2. InjectionTracer given in a vein5 minutes3. Uptake restQuiet rest in a calm room45 to 60 minutes4. ScanLie on table, scanner moves through20 to 30 minutesStep 2: The Tracer Injection
A nurse or technologist places a small cannula in your arm and injects the radiotracer, most often FDG. The amount is tiny. You usually feel nothing, although a few people notice a cool feeling at the arm. Read FDG tracer explained.
Step 3: The Resting Period
You then rest in a quiet, warm room for about 45 to 60 minutes. Avoid talking much, chewing, walking around or using the phone, because muscle activity can pull the tracer to the wrong place. Your doctor may ask you to drink water or, for some scans, a special oral liquid. Some centres ask you to empty your bladder before the scan.
Step 4: The Scan Itself
You lie on your back on a narrow table, often with arms raised above the head. The table moves slowly through a ring-shaped scanner. The CT part is done first, followed by the PET part. You must stay still and breathe normally. Staff can see and hear you throughout. Most scans cover from the skull base to the thighs, and some cover the whole body. See what a PET CT scan is.
After the Scan
- You can eat and drink normally unless told otherwise.
- Drink extra water to help the tracer leave your body.
- Go to the toilet often during the first few hours.
- Keep a small distance from pregnant women and infants for a few hours, if your centre advises.
See PET CT side effects and radiation safety.
A Practical Example
Ahmed, 45, has a 10 AM appointment. He reaches at 9:45, sugar is 108 mg/dL, and the tracer is given at 10:10. He rests until 11:10, the scan runs from 11:15 to 11:40, and he leaves by noon. His report arrives the next day. Knowing the timeline helped his family plan lunch and travel.
Getting Your Report
A nuclear medicine physician or radiologist studies both PET and CT images. A report is usually ready in 24 to 48 hours. See PET CT report and SUV values.
Quick Summary: PET CT Procedure in Five Points
- Blood sugar is checked first.
- The tracer is injected in a vein.
- You rest quietly for 45 to 60 minutes.
- The scan takes 20 to 30 minutes.
- You can go home and resume normal life, with simple precautions.
Tell the team at once if you feel unwell, have pain at the injection site, or feel anxious. They can pause and help you. If you are unsure about preparation, read PET CT scan preparation before your visit. For safety concerns, read PET CT radiation and safety.
Frequently Asked Questions
How long does the PET CT scan take?
The scan takes 20 to 30 minutes. The full visit takes about 2 to 3 hours.
Is the injection painful?
It feels like a normal needle prick.
Why do I have to rest after the injection?
The tracer needs time to spread and be absorbed by tissues.
Can I move during the scan?
No. Stay still, as movement blurs the pictures.
Do I have to be in a tunnel?
The scanner is a ring that is shorter than an MRI tunnel, so many people find it easier.
Can I use my phone during resting time?
Avoid it. Resting quietly gives better images.
Will I feel anything after the injection?
Most people feel nothing. Rarely, mild effects like a metallic taste occur.
Can I go to work after the scan?
Usually yes. Follow your centre's advice on contact with pregnant women and infants.
Can a family member stay with me?
They usually wait outside, because of radiation safety rules.
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.
