Uncertainty analysis in X-ray spectra simulation: Effect of geometric tube features: (Anode angle and filter thickness)

Knowledge of the primary X-ray spectrum in the radiodiagnostic energy range is essential for evaluating dose image quality and absorbed dose to patients. In this work, the X-ray production of a commercial device has been simulated using the Monte Carlo (MC) code, MCNP5. Simulated spectra have been compared with theoretical ones extracted from IPEM 78 database to perform an uncertainty analysis of the model. The uncertainty in the MCNP5 model is due to the combination of statistical, physics and input uncertainties. This work has been focused on the analysis of uncertainty associated to some geometrical features of the tube and its effect on the simulated spectra using the Noether-Wilks formula. The geometrical features considered are anode angle and thickness of collimators, shielding, beryllium and aluminium filters. The uncertainty in the MCNP5 simulation results due to the input parameter uncertainties was found to be more significant than the statistical uncertainty component.