Low energy dosimetry with photon counting pixel detectors such as Medipix

The use of a semiconductor photon counting pixel detector like the Medipix detector [1] [2] in a dosimeter offers the possibility to take the photon energy dependence of the personal dose equivalents especially in the low energy range below 50 keV into account Furthermore the measuring range can be extended down to low photon energies of about 10 keV. In this contribution we restrict our considerations to the medical diagnostic energy range from 10 to 150 keV. Due to the fact that the sensitive area of the Medipix detector is relatively large with (1.41cm)(2) while the sensitive area of one pixel is small with (55 mu m)(2), it is able to measure very low dose rates with high statistical precision while still processing each photon even at high dose rates. In this contribution we explain a metho to determine personal dose equivalents from photon counted data, present measurement results of the air-kerma for different X-ray qualities and show simulation results of the performance of a dosimeter based on a hybrid photon counting pixel detector. We outline the advantages and perspectives of using a photon counting pixel detector in a dosimeter.