A mammogram is an x-ray of the breast that uses a small amount of radiation. A technologist will position your breast for the test. The breast will be compressed between two plates, and a picture will be taken. Compressing the breast flattens and spreads the tissue, providing a clearer picture of the inside of the breast, making it easier to detect any changes. The technologist will then reposition the breast and the plates for a second picture. The entire process takes about twenty minutes.