Comparison of XRMC and Geant4 on dosimetry applied to mammography

The objective of this project was to compare XRMC version 6.5.0-2 to Geant4 version 10.02.p02 and the results of both Monte Carlo tools to experimental data collected by using three different mammographs for dosimetric applications in mammography (external dosimetry), validating XRMC and Geant4 for dosimetric applications in mammography. To validate the quantities simulated one experimental database was structured with data from three different mammographic equipments (Mammomat Inspiration, Mammomat 3000 and LORAD MIII). The absolute quantities exposure and kerma were collected for different setups and used to calculate the derived quantities half-value-layer (HVL) and backscattering (BSF). To evaluate the difference in results due the differences on description of the incident spectra it was modeled spectra from two different sources: catalogue IPEM Report 78 and the spectra generated for Lorad MIII equipment configuration, based on model published by Tucker et al 1991. The results show good agreement between simulated and experimental data. The XRMC is presenting similar agreement to experimental data as the results presented by Penelope model, but with a significant reduction on running time (in transmission mode it can reduces the running time, at least, similar to 5 time compared to Geant4 Penelope model) when normalized values are compared. The use of catalogued spectrum instead of experimental spectrum made visible the need of a semi-empirical correction to adjust the number of photons emitted by unit of area by total tube transported charge.