How does a pet scan employ elementary particles?
) is incorporated in a organic compound that will localize to the desired tissue. When the compound arrives at the tissue, it can then under go decay and emit a positron. This positron will annihilate with the first electron it encounters, converting both their masses to energy. This energy is expressed as two gamma photons travelling in directly opposite directions so as to conserve momentum. These gamma photons are detected by the PET scanner and when a large number of the atoms are decaying, the computer can use the relative time differential (nanoseconds) between the arrival of the two photons to calculate the position of its origin and render a 3D image of the tissue.
