Radiotherapy uses precisely targeted high- energy rays to kill cancer cells. It does this by damaging a cell's internal components (molecules), causing the cells to commit suicide by apoptosis. When a high-energy ray hits a molecule, it can cause it to break up. This can form free radicals, which can cause further damage to the inside of the cell.

Some rare metals, for example radium, emit high- energy gamma-rays naturally. In other cases, radiation can be produced in a special machine, where a metal element is heated to produce electrons. These accelerate in an electric field towards a piece of tungsten metal, which then emits high-energy x-ray when they hit it.

Wilhelm Röntgen, a German physics professor, discovered x-rays in He gave a lecture called "Concerning a New Type Of Ray", which caused a revolution in the scientific community. Just weeks later, Emil Grubbé, a student doctor in Chicago, became the first person to use of radiation to treat cancer. And three years later, two Swedish doctors used radiotherapy to cure several cases of head and neck cancer. In 1901, Röntgen was awarded the Nobel Prize for his discovery.

Side effects are problems that can happen as a result of treatment. They may happen with radiation therapy because the high doses of radiation used to kill cancer cells can also damage healthy cells in the treatment area. Side effects are different for each person But it can also work out for the good and kill just the bad cells and save organs and save from surgery.