and X-rays and long half-life are not suitable for imaging in
humans, any tracers labeled with I-125 can also be labeled with
I-123 which emits gamma-rays at a higher energy (159 keV).
Iodine-123 has a much shorter half-life (13.3 hours) which,
together with its energy, makes it more suitable for human
imaging applications. This adds to the versatility of the use of
this isotope.