The SpekPy toolkit for modelling X-ray tube spectra: Extension to transmission targets and additional target materials

SpekPy is a software toolkit for the Python programming language and designed for modelling X-ray tube spectra. The tookit is used in industry, higher education and research around the world. Previously SpekPy has only had the capability for modelling so-called 'reflection' geometry X-ray tubes with thick target anodes consisting of the elements Mo, Rh or W. This work describes extensions in release v2.5 to include four new target elements - Cr, Cu, Ag and Au - as well as modifications to model transmission targets. Predictions for a variety of tubes were compared to results from simulations using the PENELOPE general-purpose Monte Carlo code system and to experimental spectra provided by a manufacturer. Agreement was excellent. If the target thickness was greater than 20% of the continuous slowing down approximation range for the material, the predicted total fluence was within 10% of Monte Carlo results and the discrepancy in spectral shape was negligible. Agreement with experimental spectra was also encouraging. The described advances will permit more types of X-ray tubes to be modelled by SpekPy, extending its usefulness to scientists in a broader range of applications.