ABSTRACT
There are three basic considerations when choosing a radionuclide for targeted
radiotherapy:
The types of radionuclide decay that are of greatest potential use in unsealed source
therapy are those which involve the emission of b-particles, Auger and conversion electrons,
and a-particles. These particles can be considered as nonpenetrating radiation in contrast with
x-and g-rays, which are penetrating radiation. Although the b-emitters
I and
P have been
the most commonly used radionuclides in the past, their physical properties are not necessarily
ideal. Other b-emitting radionuclides have been introduced into the clinic, especially over the
last couple of decades. Emitters of Auger and conversion electrons and a-particles may be more
widely used in the future (see Section 57.3 and Section 57.4).
