Consider the energy spectrum of the x-ray radiation, how and why is it controlled, how photons of different?

Question

Consider the energy spectrum of the x-ray radiation, how and why is it controlled, how photons of different energies interact with tissues, how different x-ray energies are utilized in x-ray imaging methods.

Answer 1

Different imaging techniques typically utilize differential matter densities to make certain areas opaque, lucent, dark, or light, based on impedance of whatever ray is passed through the subject. For example, on a CT-scan, x-rays are passed through the patient, and may look lighter where a structure is denser or more-solid, and darker where structures may contain gas, or fluid.