5.8 PET Scanning

Question 1

What are PET scans?

Answer 1

Positron emission tomography (PET) is a medical imaging technique that uses radioactive isotopes to visualise organ function and diagnose medical conditions.

Question 2

How do PET scans work?

Answer 2

• Radioactive isotopes, known as tracers, are injected into the patient’s bloodstream.
• The tracers spread throughout the body and emits gamma radiation. Most of the tracers will go to the sites in the body that are most metabolically active (as they will have the best blood supply).
• The patient will lie in a PET scanner which will detect where the gamma radiation is being emitted from.
• By seeing where most of the gamma radiation is being emitted from, the doctors can see where the tracers are concentrated, and use this to diagnose medical conditions.

Question 3

Why do the tracers used in PET scans need to be made nearby?

Answer 3

• The radioactive isotopes used in the tracers have short half-lives (to minimise harm to the patient).
• This means that they have to be made near the hospital as otherwise they would decay before they can be used. Some hospitals have their own cyclotrons to make their own tracers.

Question 4

What does PET stand for?

Answer 4

Positron emission tomography

Question 5

What type of radiation is detected in PET scans?

Answer 5

Gamma