How does a PET scan work?

Meet Dave. He's about to have a brain scan using the latest PET imaging technology doctors will see Dave's brain at work it's all possible because of tiny tracers specially-designed radioactive molecules The PET scanner tracks the position of the tracers inside Dave revealing his brain function in three dimensions The tracers don’t come from a stockroom shelf Each one has to be made fresh at a nearby laboratory This is DrMiller He’s making the tracer for Dave’s PET scan First he needs to produce the radioactivity using a device called a Cyclotron It smashes high-speed particles into ordinary atoms transforming them into new, radioactive atoms. now the clock is ticking The new atoms are giving off their radioactivity becoming plain old regular atoms again there goes one It means DrMiller and his team have to work quickly to build the tracer a biological molecule This is what makes PET so unique the molecule could be anything a sugar a protein a hormone Each one is tailored to a specific function in the body and will show doctors where in the body that function is happening DrMiller’s team run special chemical reactions to create a tracer from a drug used in the brain The new tracer must pass quality control it is purified… …and checked that it will function properly.

The tracer is ready to use. Good work DrMiller! The precious custom-made molecule is rushed to the PET clinic Just the right level of radioactivity is measured out then it's injected into Dave's bloodstream.

There'll be a sharp scratch it's not long before Dave's brain has absorbed the tracer and the clever chemistry gets to work. Inside Dave an incredible reaction is taking place The radioactive atom on the tracer loses its radioactivity giving off a subatomic particle called a positron. It’s just like the tiny negatively charged electrons found on all atoms except that the positron is positively charged so when the positron hits an electron at just the right speed they combine and destroy each other the energy is released as two gamma rays that travel straight out of Dave's body in opposite directions The PET Scanner is like a big ring of Geiger counters.

When it detects two gamma rays on opposite sides of the ring… …the doctors can calculate where in Dave’s body the tracer must be. By detecting thousands of these events every second and with some clever computer processing Dave’s brain activity is revealed in three dimensions. Something no other imaging technique can do.

For Dave it was just a small injection that wasn't so bad huh? All made possible by the incredible technology of the tracer. The potential for PET is enormous Different tracers can detect cancer test heart function and even track Alzheimer’s.

The PET scan has revealed Dave’s brain is functioning as it should Dave you're A OK In the next hour or so his radioactivity levels will be back to normal it's another successful job for the incredible tracers But the work of DrMiller goes on as he continues creating new tracers, to help those in need.