The invention provides x-ray-based breast imaging systems and related methods that are, for example, applicable to contrast enhanced digital mammography and contrast enhanced digital breast tomosynthesis and allow fast, cost-effective and accurate x-ray imaging. The partitioning frame has an annular inner and outer surface. The powertrain includes an engine and torque converter that is continuously connected to one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The SD interface socket can be inserted with a SD flash memory card and the USB plug can be connected to other information devices.