Here’s what radiation treatment is about. No radiation oncologist would ever explain the mechanics of his magic to me, so I had to get most of this from the Internet. But the brief information here has been reviewed and approved by people who know better than I, so I believe you can rely on it.

Radiation is made up of tiny “energy packets” called photons. A linear accelerator (the big machine in the x-ray room) excites atoms until they spit out photons at the speed of light. These rays – precisely focused on a part of the body believed to contain cancer – tear through tissue, breaking the DNA in the nucleus of each cell they strike.

Every cell in our bodies has two key characteristics that make radiation therapy work. First, cells can repair their own DNA when it is broken; this serves to assure that all daughter cells are exact replicas of their mothers. (But cells can only repair their DNA if they have enough time before they reproduce.) Second, if a cell tries to reproduce while its DNA is broken, it self-destructs; this serves to protect tissue and organs from mutant cells that would change their nature and make them dysfunctional.

Since cancer cells reproduce very quickly, they rarely have enough time to repair their DNA, and they self-destruct when damaged by radiation. Unfortunately, this also applies to other fast-growing tissue like mucous membrane, hair and skin.