Mammography is a non-invasive technique that helps physicians diagnose. A mammogram is basically an X-ray picture of the breast. A mammography unit is a specific type of X-ray for breast imaging. Mammography uses low radiation dose X-rays to detect breast cancer early, before women experience symptoms. Like all X-ray units, mammograms use doses of low ionizing radiation to generate images. However, sometimes low doses of ionizing radiation can increase the risk of longer term effects, such as cancer. In this paper, our purpose was to compare patient radiation doses and patient lifetime attributable risks. We measured patient doses and background radiation in two different mammography units (digital, analogue).