2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/218048We describe an extension to the Geant4 software package that allows it to be used as a general purpose X-ray tracing package. We demonstrate its use by building a model of the X-ray optics of the XMM-Newton, calculating its effective area, and comparing the results with the published calibration curves.9 pages, 5 figures, accepted for publication by NIMA, DOI knownData Analysis, Statistics and ProbabilityAstrophysicsOpticstext