Energy dependence in dental imaging with Medipix2

The possibility of achieving better contrast in dental images by selecting specific X-ray energies is investigated. By applying both the low- and the high-photon counting energy threshold of the Medipix2 chip, only a narrow interval of the spectrum of a 60 keV standard dental source used is selected. The relative contrast between the parts of the tooth with the highest and lowest absorption increases 18% when the energy spread of the X-rays is narrowed from the full spectrum to a 4 keV window centred around 30 keV. The small tail of high-energy photons from the full source spectrum lowers the achieved relative contrast significantly. This result can be used in the development of X-ray sources or in consideration of energy weighting.