Characterizing and minimizing uncertainties in diagnostic X-ray beam calibrations using a Monte Carlo-based model and experimental validation.

Abstract

This study aims to develop a flexible Geant4 application capable of modeling all IEC 61267 defined radiation qualities for the HOPEWELL Designs 225 kV X-ray generator, while systematically analyze the impact of various environmental and systematic factors. Using Geant4, we replicated the experimental setup of the LEGEX laboratory and simulated all IEC 61267 radiation qualities by adjusting relevant beam parameters. The model was validated by comparing simulated HVLs and spectra, measured with a CdTe X-123 spectrometer against experimental data, SRS78 software results, and IEC reference values. The simulation demonstrated strong agreement with experimental measurements and published data, confirming the validity of our Geant4 application. We derived the function that characterizes the behavior of Kinetic Energy Released per unit Mass (KERMA) in response to variations in each influencing factor. Geometrical misalignment is the primary contributor to deviations, followed by aluminum purity and diaphragm movement, while environmental factors induced minor fluctuations. Additionally, we quantified backscattered radiation and applied corrective measures to eliminate its impact on measurements. The developed Geant4 application provides a reliable tool for simulating IEC 61267 radiation qualities and optimizing dosimetric accuracy. Our framework offers a cost-effective alternative to replicate different scenarios multiple times to identify and minimizes uncertainties.