This applet uses a very simple model for the X-Ray spectrum.* The bulk of the spectrum is due to Bremsstrahlung while the reminder is from the characteristic X-Rays. The spectrum is further shaped by intrinsic filtering by the anode materials (since the X-rays are generally created beneath the surface of the anode).

Bremsstrahlung

• I(E)∝ Z(T−E)
• T = electron’s kinetic energy

Characteristic X-Rays (K-shell)

• I_K∝(T−E_K)^1.65
• E_K =K shell binding energy

Intrinsic Filtering: energy dependent attenuation of X-rays

• electrons penetrate anode
• attenuation by X-ray tube components
• modeled as: Z=29, ρt= .1 g/cm²

Additional Filtration

• filtration by design for diagnostic X-ray imaging
• beam “hardening” + attenuation

*Following simplified models from discussion in “Semiempirical model for generating tungsten target x-ray spectra” Douglas M. Tucker, Gary T. Barnes, and Dev P. Chakraborty, Med. Phys. 18, 211 (1991)