The Awesomeness of Positron Emission Tomography (PET)

If you are an astronomy or science buff, you probably heard about antimatter. These weird things are the “opposite” of matter, and when they collide with matter, they annihilate each other and this explosion releases a ridiculous amount of energy—comparable to that generated in a nuclear blast.

Scientists imagine that in deep space there are large pockets of antimatter. Sure, deep space has lots of weird things in it. But what’s more awesome is the fact that each day, thousands of patients undergo an medical imaging test called Positron Emission Tomography (PET), and in this procedure, we generate antimatter inside the patient’s body.

PET involves injecting fludeoxyglucose (18F) into the patient. This molecule contains the radioactive isotope fluorine-18, which in its decay process, releases positrons, the antimatter to electrons. The positrons, as soon as they come into existence in the patient’s body, immediately collide with electrons in a matter-antimatter reaction. The energy from this collision is so great that gamma rays are produced! These gamma rays hit the combined CT scanner and PET detectors, and with the help of powerful software, we can triangulate the location of the emissions in the patient’s body.

Of course, one common use of PET is the detection of metastatic cancer. Most tumors typically absorb and consume far more glucose than normal tissue. Because of this, they will absorb a disproportionately larger amount of the fludeoxyglucose, and thus more gamma rays will be produced from inside these tumors. This translates to “bright spots” on the PET images.