[Pontiac]

The ray could have several uses, such as in medical imaging, radiotherapy and radioisotope production for PET (positron emission tomography) scanning.

This is new to me. What nuclear reaction produces radio isotopes using gamma rays.

If I recall my high school physics correctly you have to add a neutron to make a new isotope.

How can a gamma ray do that?

[Red Badger]

http://en.wikibooks.org/wiki/Basic_Physics_of_Nuclear_Medicine/Production_of_Radioisotopes

[SargeK]

Or take a neutron away.

Can a photon (gamma) do that?

Dunno. That why me Sarge and not Professor.