Photon Interaction Data ("cross sections")

• XCOM: Photon Cross Sections Database
• Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients by JH Hubbell and SM Seltzer of NIST.

Electron Interaction Data

• Electron-Impact Cross Sections for Ionization and Excitation at NIST
• STAR Database: Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions at NIST

Diagnostic X-Rays

• Boone JM, Seibert JA, An accurate method for computer-generating tungsten anode x-ray spectra from 30 to 140 kV. Med Phys 24(11), 1661-1670 (1997).  See http://www.edonnelly.com/genspectrum.php for a nice web-based implementation of the algorithm.
• Boone JM, Fewell TR, Jennings RJ, Molybdenum, rhodium, and tungsten anode spectral models using interpolating polynomials with application to mammography, Med Phys 24(12), 1863-1874 (1997). See http://www.edonnelly.com/mamspectrum.php for a nice web-based implementation of the algorithm.