For tomosynthesis to reach its full potential, it is necessary to perform a large number of studies to find the optimal way to acquire the tomosynthesis images and the optimal way to mathematically combine these images to get the three dimensional image. In this study, we are aiming to find if the resulting three dimensional image should be divided into slices or layers each representing 1 millimeter (less than one 16th of an inch) of the breast or 5 millimeters (one 5th of an inch) of the breast. The difference between these two thicknesses in how useful the images are to the radiologist could be important. Up to now, tomosynthesis imaging has been performed with 1 millimeter slices, but there has been no scientific study to prove that this is the best slice thickness. We will try to determine if slicing the image of the breast into thicker slices will make the job of the radiologist easier or not when deciding to recommend or not a biopsy (laboratory analysis) of what the previous mammogram found. To find the answer to this question, we will image patients with our tomosynthesis machine and look at the tomosynthesis images with the thin and thick slices. The radiologists that read each image will decide if they would have recommended the patient to get a biopsy based only in each of these images. The recommendations based on the images with thin slices and the recommendations based on the images with thick slices will be compared with what was actually recommended using the standard clinical tests. We hope to show that the images with the thick slices will do as well if not better than those with the thin slices. Even if the thick slices only do as well as the thin slices, this will show that creating images with thicker slices is better, since these images can be read faster by the radiologist.