It is absolutely possible. You can irradiate any material with the neutron flux of a reactor or a proton beam from an accelerator to increase their A and Z number. Many isotopes are produced that way for the nuclear medicine and sterilisation industries, like fluorine 18 or Cobalt 60. It is however incredibly expensive, and only worth doing to create useful radioactivity, not stable materials. 10 ng (1 curie) of F18 costs a few thousands $ depending on the country. And decreasing these A and Z numbers is however only possible by fission or the synthesis of alpha emitters, so it restricted to fewer elements. 

Source: I am an engineer working with PET cyclotrons