A portable radiographic imaging apparatus for fluoroscopy comprising: a wheeled transport frame; a C-shaped support arm mounted on the frame, support arm having a fixed end that is coupled to a radiation source and, configured to oppose the fixed end, a retractable end, where the retractable end is configured to seat an imaging detector when the retractable end extends outward from the frame for imaging, where the radiation source has two or more radiation sources (804a, 804b) that are interchangeable, so that when changed, the current radiation source (804a, 804b) has the same focal spot that is of the same size and alignment as the previous radiation source (804a, 804b), and individually energizable to emit a radiation beam toward the retractable end, where the imaging detector is removable from the retractable end for free-standing operation with the retractable end of support arm in a retracted position; a switching actuator or switchable head that is configured to rotate either of the two or more radiation sources (804a, 804b) into position and to align the radiation beam from either of the two or more radiation sources (804a, 804b) along the same optical path; at least one radiation source temperature sensor element that provides a signal that is indicative of temperature near an energized radiation source; and a processor to monitor the signal from the at least one radiation source temperature sensor element and to control at least energization or alignment of the two or more radiation sources (804a, 804b) according to the monitored signal, where the processor is in signal communication with the imaging detector and with one or more displays for display of obtained images. a wheeled transport frame; a C-shaped support arm mounted on the frame, support arm having a fixed end that is coupled to a radiation source and, configured to oppose the fixed end, a retractable end, where the retractable end is configured to seat an imaging detector when the retractable end extends outward from the frame for imaging, where the radiation source has two or more radiation sources (804a, 804b) that are interchangeable, so that when changed, the current radiation source (804a, 804b) has the same focal spot that is of the same size and alignment as the previous radiation source (804a, 804b), and individually energizable to emit a radiation beam toward the retractable end, where the imaging detector is removable from the retractable end for free-standing operation with the retractable end of support arm in a retracted position; a switching actuator or switchable head that is configured to rotate either of the two or more radiation sources (804a, 804b) into position and to align the radiation beam from either of the two or more radiation sources (804a, 804b) along the same optical path; at least one radiation source temperature sensor element that provides a signal that is indicative of temperature near an energized radiation source; and a processor to monitor the signal from the at least one radiation source temperature sensor element and to control at least energization or alignment of the two or more radiation sources (804a, 804b) according to the monitored signal, where the processor is in signal communication with the imaging detector and with one or more displays for display of obtained images.