: How does cancer radiotherapy target only cancer cells? I read about cancer treatment where the patient would be given radiation to kill cancer cells. How do they make sure that it affects mostly the cancer cells? Moreover

www.cancer.gov/about-cancer/treatment/types/radiation-therapy/radiation-fact-sheet The quick answer is the healthy cells do get radiations (you may read more info on the above link), but they came up with a clever idea on how to minimalize the radiation absorbed by healthy cells but at the same time give a lot of radiation to the cancer cells. Look at this video from 1:44.

Simply enough, they used computer to analyze 3D picture of your body, then "shoots" the cancer cells from different angles so that the healthy cells get minimum damage. This doesn't relate to the question but maybe you want to know that cancer cells are weaker than normal cells because they are too busy growing and less organized that normal cells which makes them harder to recover from the radiation. That makes things a lot easier. This is link to the proof. www.breastcancer.org/treatment/radiation/how_works

---