Interaction of Photons and Charged Particles with Matter

Abstract

An x-ray image records variations in the passage of x rays through the body because of scattering and absorption. This chapter describes the mechanism by which x-rays and charged particles interact with tissue. Photons interact by several mechanisms, including the photoelectric effect, Compton scattering, and pair production. Other processes can lead to the transfer of energy between photons and electrons, such as the production of Auger electrons, bremsstrahlung radiation, and emission of fluorescence photons. The interaction of tissue with charged particles is described by their range and stopping power, and they often deposit most of their energy near the end of their path in the Bragg peak.