Yes. Gamma. Rays are photons, usually all of teh same energy, once produced by cobalt 60 machines, now in gamma knife units. Alpha particles are densely ionzing not very penetrating helium nuclei, and beta particles are electrons that do not penetrat. An x-ray generally produces a pectrum of energies, produced by the braking of electrons on a target of metal, like tungsten.
Can. Radiation usually affects cells that are dividing and since cancer cells divide more than most normal cells, radiation, including gamma rays will kill those cells, however, the effect is not specific to cancer cells, radiation kills normal cells also.