Yes thermage uses non-ionizing radiation. It uses radio waves or lower frequency microwaves to heat the layers of collagen below the skin surface. This type of electromagnetic radiation cannot ionize an atom or molecule (i.e. remove one of its electrons) and has no mutating effects that would increase cancer risks. You will feel temporary heating sensations though, which is normal as that is how you are able to stimulate collagen and tighten the skin. To put it simply, it works on the same principle as a microwave oven. The electromagnetic waves are capable of exciting electrons which makes the electron jump to a higher energy state. As it comes back from its higher energy state energy is released in the form of heat. The structure of the atom or molecule is unchanged.