A procedure that uses x-rays to take a series of pictures of the inside of the breast from many different angles. A computer is used to make 3-D pictures of the breast from these x-rays. 3-D mammography is used to check for breast cancer and other changes in the breast, such as abnormal lumps, cysts, or calcifications (calcium deposits). It may allow doctors to see breast tissue, including dense breast tissue, more clearly than with 2-D mammography. This may make breast tumors or other changes in the breast easier to find. Also called 3-dimensional mammography and breast tomosynthesis.