A breast x-ray system and method using tomosynthesis imaging in which the x-ray source generally moves away from the patient’s head. One or more register elements are carried by support strips which are placed in the cylinder barrel. A zone of valid location fixes based on the last known terrestrial navigation fix and an output of a rate detection circuit can be established. Embodiments may identify a style from a stylesheet for each feature in the map tile according to style identifiers in the feature and the style in the stylesheet. The cylindrical walls are rotatable about a second axis and the first axis, such that, during rotation of the rotor, the volumes of the rotor chambers on one side of the rotor and the rotor chambers on the other side of the rotor alternatively have a minimum value.