Monochromatic X-ray methods and apparatus

An x-ray apparatus comprising:

• an electron source configured to generate electrons;
• at least one first target arranged to receive electrons from the electron source, the at least one first target comprising material that, in response to being irradiated by the electrons, produces broad spectrum x-ray radiation;
• at least one second target arranged to receive at least some of the broad spectrum x-ray radiation, the at least one second target comprising material that, in response to irradiation by broad spectrum x-ray radiation from the first target, produces monochromatic x-ray radiation to irradiate subject matter of interest, wherein the at least one first target is configured to produce broad spectrum x-ray radiation to irradiate the at least one second target at a spatially compact region such that the at least one second target produces monochromatic x-ray radiation in response to the broad spectrum x-ray radiation to irradiate the subject matter of interest;
• and
• at least one detector positioned to detect at least some of the monochromatic x-ray radiation produced from the at least one second target and transmitted through the subject matter of interest to form at least one image of at least a portion of the subject matter of interest.