PET imaging basics
The basics of positron emission tomography imaging are discussed. Positron emission tomography (PET) is the injection (or inhalation) of a substance containing a positron emitter, the subsequent detection of the emitted radiation by a scanner, and the computation of a digital image that represents the distribution of the radiotracer in the body. Background events in PET imaging include the scattered event and the random event, which are detrimental to the quality of the resulting images. The spatial resolution of PET images is determined the positron range (the scanner sees the annihilation location, not the emission location, which is of interest) and photon noncolinearity (the annihilation photon departure trajectories are not exactly 180° apart). Quantitative use of PET data requires accurate corrections for attenuation, scatter, random events, and dead time. The first step in quantitation is producing images whose pixel values represent the radioactivity concentration of the imaged object. In addition to the various corrections, calibration factors must be determined to translate the corrected counts to radioactivity values. © 2011 Springer Science+Business Media, LLC.
