by Bryan Uber

Created on: August 20, 2009

This article explains the application of antimatter and explains the medical application of its powerful properties.

Positron Emission Tomography is the process of injecting a patient with anti matter. This anti matter is called a positron. When the anti matter stabilizes with an electron, it will emit two photons. The two photons are gamma rays and they are produced once the matter and anti matter have interacted. These gamma rays are then measured and recorded with the use of photomultiplier tubes. The photomultiplier tubes are surrounding the patient in a circular configuration. When the subject is placed in the center of the configuration this enables the computer to measure the gamma ray emission from the top and bottom of the subject. This process occurs throughout the photomultiplier tube configuration. The computer analyzes the different density of gamma rays and produces a three dimensional image from a 2 dimensional input. The most difficult aspect of positron emission tomography is the production of anti matter. Positrons are short lived; therefore the creation of anti matter must be near the location of the PET scan. The process of making a positron involves the understanding of pair production.

Pair production is one of the methods used to understand how electromagnetic radiation interacts as a particle with matter (Harris 83). In order to produce an electron-positron pair, photonic energy is used to create both the positron and electron. This occurs because all energies must be conserved. This process can be observed using a bubble chamber detector, which allows for charged particles to leave visible trails of bubbles. The chamber is immersed in a magnetic field. When high-energy photons are introduced into the bubble chamber, two charged particles deflect on similar paths but in opposite directions. Pair production was used to illustrate the physics behind converting high energy photons into electron-positron pairs. Positive beta decay allows the production of positrons (Harris 490). Other methods used to understand how electromagnetic radiation interacts as a particle with matter is the photoelectric effect and the Compton Effect.

For the PET scan, the process of electrons and positrons interacting is opposite when compared to the definition of pair production because pair production uses photonic energy to create the positron and electron pair. The PET scan involves the administration of positrons to the

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