The Comprehensive Guide To PET-CT Scans

The Comprehensive Guide To PET-CT Scans : Positron Emission Tomography And Computed Tomography (PET-CT)

A Positron Emission Tomography (PET) scan is an imaging test that allows your doctor to check for diseases in your body. The scan uses Radio-traces that are injected into a vein in your arm. Your organs and tissues then absorb the tracer.

A PET scan is typically an outpatient procedure. However, patient is instructed to avoid contact with young children & young women/pregnant ladies for about 24 hours.

Doctors use PET-CT Scans to:

  • To stage the cancer
  • Find out if the cancer treatment working
  • Evaluation of the treatment after it ends
  • Plan radiation therapy
  • Find the right place for biopsy
  • To know the viability of heart muscle


A CT (Computed Tomography) scan shows detailed pictures of tissues and organs inside the body. A PET (Positron Emission Tomography) scan shows abnormal radioactive tracer activity in the body. Both scans fused together provide more information about Cancer.

How does PET-CT Work?

After acquiring elaborate history pertaining to the patient health problems, the nurse gives you an injection of radioactive tracer intravenously. The organs in your body fix up the radioactivity; highly metabolically-active cells like cancer pick up a lot and PET-CT scan shows where the radioactive substances in your body, thus helping our doctors pin-point the location of the cancers.

A CT Scan uses X-Rays to create a 3-dimensional picture of the inside of your body. It highlights anything abnormal, including tumours. Sometimes a special dye called a ‘contrast medium’ is given by injection before the scan to provide structural details on the image.

Do these scans have risk?

Yes, these scans do have risks of radiation exposure; it’s similar to total body CT Scan done with contrast medium, which includes contrast related risk like allergy and other toxicities in a very small percentage of patients.

The benefits of these scans are usually greater than the risks.

Getting ready for a PET-CT Scan:

A blood test called S. Creatinine is to be performed before the PET-CT

  • You need to fast at least 6 hours before scan
  • If you are a diabetic do not take anti-diabetic drugs on the day of the test
  • Mention any allergies and other medical conditions
  • Pregnancy and breast feeding should be mentioned to your doctor
  • The staff ask you to sign a consent form after you have understood the risk and benefits of PET-CT Scan
  • You are asked to remove jewellery and all other metallic objects and to wear a hospital gown

What is the duration of the scan?

After you are injected with the tracer, you are instructed to drink fluids and wait for about 1-2 hrs; then you are taken to the scan room, where the scan might take another half an hour to one hour.

After this the patient will be generally allowed to have food, if no more test is required they can go home.

However the doctor decides if any further imaging in PET-CT is required.

In total, patient should be prepared to stay in the department for about 5-6 hrs.

Note: Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional.