X-rays are just like any other kind of
electromagnetic radiation. They can be produced in parcels of energy called
photons, just like light. There are two different atomic processes that can
produce x-ray photons. One is called Bremsstrahlung, which is a fancy German
name meaning "braking radiation." The other is called K-shell
emission. They can both occur in heavy atoms like tungsten.
Tungsten alloy is a kind of high density material
for radiation protection, for more details, you could visit: http://www.tungsten-alloy.com/X-ray-target-collimator.htm
