Lichen is the symbiotic association of a fungus (the mycobiont, which provides shelter and structure for the partnership or symbiosis), with an alga or cyanobacterium (the phoâ¦tobiont, also known as the phycobiont, which provides the food for the partnership from photosynthesis).
Some radiation therapy delivery methods include: 1  External beam radiation therapy â radiation is directed from a machine outside the body onto cancerous cells within the body.  Internal radiation therapy â radioactive material is placed (via a catheter or other carrier) directly into or near a tumor.
External beam therapy is the radiation therapy treatment option used for most cancer patients. It is used to treat many types of tumors including cancers of the head and neck area, breast, lung, colon, and prostate.