A cascade power system is disclosed where a single basic working composition of a multi-component working fluid stream is fully vaporized in a vaporization subsystem utilizing heat derived from a heat source stream such as a combustion gas stream and energy is extracted from the stream in a multi-stage energy extraction system. The first pair of brushes are mounted on one side and are driven by a drive motor ; the second pair of brushes are mounted on the opposite side of the cleaner. An extension tab extends from the left side wall and defines a through aperture therein. The adder adds the horizontal and vertical edge correction signals whose gains are controlled. This system can be a Nuclear Medicine imaging system to acquire Single Photon Emission Computed Tomography image information.