X-ray, a type of high-energy electromagnetic radiation, is often used for cancer diagnosis, staging and treatment.

An X-ray uses electromagnetic radiation to make images. The image is recorded on a film, called a radiograph. The images produced appear light or dark, depending on the absorption rates of the different tissues. For example, dense materials, such as bone, show up as white on a film, while fat and muscle appear as varying shades of gray.

An X-ray exam is fast and painless. In low doses, X-rays can be used to construct images of structures inside the body to detect and stage a tumor. In higher doses X-rays can be used in radiation therapy to help destroy cancerous cells in the body.