FIGURE 5. Images of gelatin breast phantom. (A) X-ray mammogram of phantom acquired at 0°. (B) PEM image of phantom acquired at 0°. Dashed box delineates outline of field of view of x-ray mammography unit. Ramp filter window function with cutoff value of 14% of Nyquist frequency was applied to image. Object in lower portion of PEM image is fiducial marker. Size scales of x-ray mammogram and PEM image are same to show differences in field of view of the 2 imagers.