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Questions & Answers

How is a PET scanner able to locate a tumour in the patient's body?

A: A PET scanner is used to locate tumours using what we call a radiotracer: a safe radioactive chemical that is injected into the body. A higher concentration of this chemical is sent to the tumour areas, since these clusters of cells require more blood than regular cells. Since the radioactive isotope chosen has a short half-life, meaning it decays into positrons pretty quickly. And it’s these positrons that combine with electrons in the body to partake in an electron-positron annihilation reaction. This creates gamma rays as a result, which are released out of the body. That’s when the PET scanner’s ring detects these gamma rays, while computers connected to these detectors pick up on these gamma ray emissions and locate the position of the tumor.

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