
Basics of nuclear imaging 139
E
0
Photoelectron
Incident photon
~v
Electron b ounded in atom
FIGURE 5.6 Diagram of the photoelectric interaction. The energy of the incident
photon is transferred to one of the electrons. The electron is ejected from the atom
with the kinetic energy equal to t he difference between E
0
and the binding energy
of the electron.
The original gamma ray is considered to be attenuated when it interacts
with the matter through any possible interaction. The C ompton scatter (Sec-
tion 5.1.2.1) and photoelectric effect (Section 5.1.2.2) are the two main inter-
actions that photons undergo while passing through matter in the rang e of
energies ...