Question

What is an “X ray” (radiograph)—what creates the image?

What sort of radiation is involved? Are X rays “perfectly safe”? If not, what are the dangers?

Answer 1

X-ray is an electromagnetic wave of high energy and very short wavelength, which is able to pass through many materials opaque to light.

Working
To produce an X-ray picture, an X-ray machine produces a very concentrated beam of electrons known as X-ray photons. This beam travels through the air, comes into contact with our body tissues, and produces an image on a metal film.

Soft tissue, such as skin and organs, cannot absorb the high-energy rays, and the beam passes through them. Dense materials inside our bodies, like bones, absorb the radiation.

Much like camera film, the X-ray film develops depending on which areas were exposed to the X-rays. Black areas on an X-ray represent areas where the X-rays have passed through soft tissues. White areas show where denser tissues, such as bones, have absorbed the X-rays.

X-rays are a type of light ray, much like the visible light we see every day. The difference between visible light and X-rays is the wavelength of the rays. Human eyes cannot see light with longer wavelengths, such as radio waves, or light with shorter wavelengths, such as X-rays.

Risk
X-rays can cause mutations in our DNA and, therefore, might lead to cancer later in life. For this reason, X-rays are classified as a carcinogen by both the World Health Organization (WHO) and the United States government. However, the benefits of X-ray technology far outweigh the potential negative consequences of using them.