Monochromatic x-ray imaging systems and methods

An x-ray system comprising:

• an electron source configured to generate electrons;
• a primary target arranged to receive electrons from the electron source to produce broadband x-ray radiation in response to electrons impinging on the primary target;
• and
• a secondary target comprising:
• at least one first layer of a first material that produces monochromatic x-ray radiation at a first energy in response to absorbing incident broadband x-ray radiation emitted by the primary target;
• and
• at least one second layer of a second material that produces monochromatic x-ray radiation at a second energy in response to absorbing incident broadband x-ray radiation emitted by the primary target,
• wherein the first energy and the second energy are different, and wherein the broadband x-ray radiation irradiates both the at least one first layer and the at least one second layer so that the x-ray system simultaneously emits monochromatic x-ray radiation at the first energy and monochromatic x-ray radiation at the second energy to irradiate a sample;
• and
• a detector for detecting x-ray radiation emitted by the secondary target at the first energy and the second energy that are transmitted through the sample to form at least one image of the sample.