II.A.5.     The rest mass energy of an electron is used in:

    a.     X-ray production.    No

    b.     Calculation of radionuclide doses.    No

    c.     Determining Compton scattering.    No

    d.     Positron emission tomography.    Yes

   Discussion:    The radiation photons in PET are produced by the annihilation of a positron and an electron. It is the mass of the electron and positron that is converted into energy.

   Reference:    Physical Principles of Medical Imaging, 2nd Edition. p. 27