Radiation and Radiography
Radiation is a key tool in radiography. X-rays and Gamma radiation (as well as other forms of EM radiation such as visible light) are used to see inside of the human body without physically damaging it. X-ray machines work like this: denser objects (like bone) absorb more of the x-rays the machine releases, than softer tissue. the X-rays that pass through the body successfully are absorbed by a film.