X-ray spectra by means of Monte Carlo simulations for imaging applications

X-ray tubes have a broad range of applications worldwide, including several techniques for atomic physics, like X-ray fluorescence, as well as for medical imaging, like computed tomography. The performances of X-ray imaging detectors have shown to be significantly sensitive to the incident beam spectrum. Therefore, an accurate knowledge of the X-ray beam becomes necessary for the emission source characterization and the whole imaging process comprehension. Direct measurements and suitable Monte Carlo simulations may be used to establish the X-ray spectra. Dedicated Monte Carlo simulation routines, based on the PENELOPE code, have been developed to determine the Bremsstrahlung X-ray spectra generated by conventional X-ray tubes. The simulated spectra have been validated by comparison with the corresponding experimental data showing an overall good agreement. The incorporation of a suitably designed virtual grid allowed to assess the angular distribution of Bremsstrahlung yield, showing a remarkable anisotropy. In addition, a dedicated program has been developed for virtual imaging, which enables to perform suitable X-ray absorption contrast images. Also, the developed program includes a user-friendly graphic interface to allow the upload of required input parameters, which include setup arrangement, beam characteristics, sample properties and image simulation parameters (spatial resolution, tracks per run, etc.). The software includes dedicated subroutines which handle the physical process from X-ray generation up to detector signal acquisition. The aim of the developed program is to perform virtual imaging by means of absorption contrast and using conventional X-ray sources, which may be a useful tool for the study the X-ray imaging techniques in several research fields as well as for educational purposes. The performed comparisons with experimental data have shown good agreement. The obtained results for X-ray imaging may constitute useful information for the comprehension and improvement of X-ray image quality, like absorption contrast optimization, detail visualization, definition and detectability. Copyright (C) 2010 John Wiley & Sons, Ltd.