For dental and facial imaging, a source of x-rays (14) or other penetrating radiation and a detector (20) are mounted opposite one another on a rotatable gantry (28), so that the head of the patient can be positioned between the source (14) and the detector (20), with the axis of rotation (36) of the gantry passing through the patient's head. The detector or the source are mounted so they can translate and/or pivot horizontally or vertically. The gantry is angulated so that the source or the detector may not be at the same height relative to the patient's head. The gantry can telescope, moving the source and the detector closer together or further apart. The collimator changes dynamically with the motion of the gantry and/or the source and detector to scan a smaller portion of the scan field.