Gamma Radiation

Which tracer is used for imaging with a gamma camera?

Technitium-99m

Which tracer is used in PET scanning?

Fluorine-18

Why are gamma emitting sources useful for imaging inside the body?

They are the least ionising and can penetrate through a patient to be detected externally.

Why are short half-lives necessary for the radioisotopes used for medical imaging?

To ensure a large activity from a small amount and to minimise radiation dose after the procedure.

What is a medical tracer?

A compound containing a radioisotope that is put into the patients body.

What is the function of a collimator in a gamma camera?

To absorb any photons not travelling along the axis of the tubes so the source location of gamma radiation can be idenitifed.

What is the function of a scintillator in a gamma camera?

It produces many photons of visible light when a gamma photon interacts with it.

What is the function of the photomultiplier tubes in a gamma camera?

They convert visible light photons to an electrical pulse.

What is the function of the computer in a gamma camera?

It processes the signals from the photomultipliers to locate where the gamma ray originated to produce an image showing the concentrations of medical tracer.

What type of radiation is detected in a PET scan?

Gamma

What type of radiation is emitted by Fluorine-18 nucleus in a PET scan?

Beta plus/positron

How is the the source of the gamma photons located in a PET scan?

By the time delay between the arrival of diametrically opposite gamma photons.