Apparatus and method for spectral projection imaging with fast KV switching

A CT system includes a gantry, an x-ray source configured to project x-rays toward an object, an x-ray detector positioned to receive x-rays from the x-ray source that pass through the object, a generator configured to energize the x-ray source to a first voltage and to a second voltage that is distinct from the first voltage, and a controller configured to cause the gantry to position the source and generator at a circumferential position during an imaging session, pass the object through the opening during the imaging session, cause the generator to energize the x-ray source to the first voltage and to the second voltage, acquire imaging data while the generator energizes the x-ray source to the first voltage and to the second voltage while the rotatable gantry is at the circumferential position, and generate an image using the imaging data.