Systems and methods for breast x-ray tomosynthesis that enhance spatial resolution in the direction in which the breast is flattened for examination. In addition to x-ray data acquisition of 2D projection tomosynthesis images ETp1 over a shorter source trajectory similar to known breast tomosynthesis, supplemental 2D images ETp2 are taken over a longer source trajectory and the two sets of projection images are processed into breast slice images ETr that exhibit enhanced spatial resolution, including in the thickness direction of the breast. Additional features include breast CT of an upright patient's flattened breast, multi-mode tomosynthesis, and shielding the patient from moving equipment.