ABSTRACT
An advanced analytical model for the x-ray spectra emitted from an x-ray tube is described in detail in this chapter. The model incorporates a thorough treatment of the electron transport, utilizing Monte Carlo-simulated distributions of the number of electrons at depth in the target and the energy and direction at each depth. The cross-sections used in the model are based on the tabulations of the National Institute of Standards and Technology (NIST) for the single-differential bremsstrahlung cross-section and partial-wave calculations of the shape function (i.e., the intrinsic bremsstrahlung angular distribution). The depth-distributions for characteristic x-ray production are also based on simulated data. The resulting emissions—both bremsstrahlung and characteristic x rays—are shown to be in excellent agreement with full Monte Carlo simulations. The model has been implemented in the SpekPy-v2 toolkit (Poludniowski et al. Med Phys. 2021;48(7):3630-3637) along with several alternative physics models and approximations.
