PET scanning

Need to know

What you need to know

• A **radiotracer** is injected into the patient. This is a biologically active molecule combined with a short-lived radioactive isotope that emits positrons (a positron-emitter).
• A very common tracer is **Fluorodeoxyglucose (FDG)**, which is an analogue of glucose. It contains the positron-emitter Fluorine-18.
• Cells with high metabolic rates, like cancer cells or active brain cells, consume large amounts of glucose. They readily absorb the FDG tracer.
• The Fluorine-18 nuclei within the FDG undergo **beta-plus (β⁺) decay**, emitting a positron.

Explanation

PET scanning

1. A **radiotracer** is injected into the patient. This is a biologically active molecule combined with a short-lived radioactive isotope that emits positrons (a positron-emitter).
2. A very common tracer is **Fluorodeoxyglucose (FDG)**, which is an analogue of glucose. It contains the positron-emitter Fluorine-18.
3. Cells with high metabolic rates, like cancer cells or active brain cells, consume large amounts of glucose. They readily absorb the FDG tracer.
4. The Fluorine-18 nuclei within the FDG undergo **beta-plus (β⁺) decay**, emitting a positron.