The present disclosure relates to an X-ray source system configured for successively or concurrently generating different X-ray spectra, which have different cutoff-energies. The system comprises an electron receiving member, which is mounted to be rotatable about a rotation axis. The electron receiving member comprises a conversion structure and a substrate. The system further comprises a voltage generator, which is connected to the electron source and which is configured to control the electron source so that electrons having a first energy and a second energy are generated using different acceleration voltages of the electron beam source. The first energy is greater than the second energy and a ratio of a transmittance for the electrons of the first energy through the conversion structure to a transmittance for the electrons of the second energy through the conversion structure is greater than 1.2.
