PET Scan
A PET (positron emission tomography) scan uses a small amount of radioactive tracer to show how active tissues are. It is often combined with CT and is especially useful in cancer care.
Causes & risk factors
- To find or stage cancers
- To check how well cancer treatment is working
- To look for cancer spread in the body
- To assess some heart and brain conditions
- To help tell active disease from scar tissue
- To guide biopsy or treatment planning
Common symptoms
Tests & diagnosis
Treatment & management
- A small amount of radioactive tracer is injected first
- You rest quietly for about an hour while it spreads
- The scan itself is painless and takes around 30 minutes
- You may be asked not to eat beforehand and to avoid strenuous activity
- The radiation leaves the body within hours — you may be asked to avoid close contact with pregnant women and young children briefly
When to see a doctor urgently
- When your specialist needs to stage a cancer or check treatment
- To look for whether a cancer has spread
- As part of planning cancer treatment
Not a diagnosis. MedDroid gives general educational information about pet scan. It cannot examine you, diagnose or prescribe — always confirm with a qualified doctor.
Frequently asked questions
Is the radioactive tracer in a PET scan harmful?
The amount used is small and leaves your body within hours. As a precaution you may be asked to keep your distance from pregnant women and young children for a short time afterwards.
Why combine PET with CT?
A PET scan shows how active tissue is, while CT shows detailed anatomy. Combining them (PET-CT) pinpoints exactly where active disease is, which is very useful in cancer care.
Explore more
MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.