How are they made-
Gamma rays are given off by stars, and by some radioactive substances.
They are extremely high frequency waves, and carry a large amount of energy.USES-Because Gamma rays can kill living cells, they are used to kill cancer cells without having to resort to difficult surgery.This is called "Radiotherapy", and works because healthy cells can repair themselves fairly well when damaged by gamma rays - but cancer cells can't. Getting the dose right is very important!There's also targeted radiotherapy, where a radioactive substance is used to kill cancer cells - but it's a substance that'll be taken up by a specific part of the body, so the rest of the body only gets a low dose. An example would be using radioactive iodine to treat cancer in the thyroid gland.