Why is gamma ray radiation used in treating cancers?

Gamma rays are sometimes used in treating cancer because of what they are and what they do. Gamma rays are electromagnetic radiation. Just like light or radio waves. Except that they are of a much higher energy than light or even X-rays. They are absorbed or scattered by anthing they pass through, and their ability to penetrate material and the amount of scattering they experience varies as the material. But they penetrate stuff pretty well, and slice right through biological stuff like plant or animal tissue. And they do stuff to the tissue they pass through while zipping past. The high energy of gamma rays is what is called ionizing radiation. It has the power to break chemical bonds between atoms. This is important because living tissue is made up of complex chains of atoms. Big organic molecules are the basics of life. If a gamma ray zips by, it can break the big molecule apart kind of like snipping a string in a place or two with scissors. The gamma ray loses energy doing this, but it still continues on cutting up molecules. It causes radiation damage. Electromagnetic radiation (emr) damage. And this can be good. It turns out that though emr damage can make living cells "sick" and can also kill them if enough damage occurs, the cells that are most sensitive to emr damage are cells that have "fast metabolisms" or that work at high rates. Cancer cells work at high rates. Irradiate them with high energy emr (gamma rays) and they can be killed. So will some surrounding tissue, but the brunt of the damage will be caused to the cancerous tissue. And by moving the beam around, we can minimize damage to surrounding tissue while pounding the cancerous cells. This is the basis for current radiation therapy by gamma rays.