Does radiation therapy involve the use of chemicals, or is it like using a ray gun?

Linear Accelerator: Ray gun. I like that. Electrons are accelerated towards tungsten and the braking (slowing down of these when they hit) creates the x-rays. Different energies can be made depending on the voltage levels. No chemicals are used. Old days cobalt-60 was a radioactive substance in the machine that gave off these xrays. Its the same kind as xrays for pictures but for therapy the energies are higher.

X-rays, no chemical: Usually the form of radiation used is high energy x-rays. These are produced by high energy linear accelarators. Protons and gamma rays are to name a couple more forms of radiation. There is no chemical.