Radiation therapy is the use of high-energy X-rays to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external radiation therapy) or from putting materials that produce radiation (radioisotopes) into the body.
Screening tests help your doctor look for a problem before you have symptoms. This increases your chances of finding the problem early, when it's more treatable.Studies don't show that routine screening for lung cancer is right for most people. But it may help those who have the highest risk for lung cancer—people 55 and older who are or were heavy smokers.Lung cancer screening is done with a low-dose CT scan. A CT scan uses X-rays, or radiation, to make detailed pictures of your body. Who should be screened for lung cancer?Annual lung screening is only recommended for heavy smokers. That means people with a smoking history of at least 30 pack years. A pack year is a way to measure how heavy a smoker you are or were. To figure out your pack years, multiply how many packs a day (assuming 20 cigarettes per pack) you smoke by how many years you have smoked. For example:If you smoked 1 pack a day for 15 years, that's 1 times 15. So you have a smoking history of 15 pack years.If you