Purpose: Monochromatic X-ray sources are effective in contrast imaging, especially when their energy matches the contrast’s K-edge. In this study, we evaluated the performance of the quasi-monochromatic X-ray source based on reflective thin-film Cerium oxide (CeO₂) target deposited on a diamond substrate.
Methods: A thin-film target produces isotropic discrete k-lines and forward-distributed anisotropic white Bremsstrahlung x-rays. In the reflective direction, a quasi-monochromatic spectrum can be obtained when the Bremsstrahlung production is largely suppressed. Monte Carlo simulations were performed using Geant4 software to calculate the spectrum from the thin-film target of various thickness bombarded by electrons with energies ranged from 100-450keV. The absorbed dose in a water block was also simulated in Geant4 for each incident spectrum. The signal-to-noise ratio (SNR) and contrast to noise ratio (CNR) of a 4.5 cm water with iodine contrast were calculated based on the predicted spectrum and with that of conventional mammography x-ray sources under the same dose conditions.
Results: Monte Carlo simulation shows that the Bremsstrahlung's production by the thin-film target decreases with electron energy and increases with the thin-film thickness. Comparing with conventional mammography sources, the same SNR and CNR of iodine images can be achieved by the quasi-monochromatic source with Cerium target but with 2 to 3 times lower x-ray exposure.
Conclusion: The x-ray source with a CeO₂ thin-film target can produce a quasi-monochromatic spectrum that matches the K-edge of iodine to enhance the contrast. It may reduce x-ray exposure and increase CNR of iodine contrast in mammography.
Not Applicable / None Entered.