PMID: 11929014Apr 4, 2002Paper

The x-ray sensitivity of amorphous selenium for mammography

Medical Physics
Mary F StonePavel Rehak

Abstract

A study of the x-ray sensitivity of amorphous selenium (a-Se) for digital mammography has been performed. A uniform layer of a-Se was deposited on a glass substrate with electrodes on both surfaces. The deposition procedure was identical to that used for a-Se flat-panel detectors. A high voltage was applied to the top surface of the a-Se layer in order to establish an electric field E(Se). Then the sample was exposed to x rays with 27 kVp spectra generated from an x-ray tube with a molybdenum (Mo) target. The mean x-ray energy of the spectrum used was approximately 16.6 keV. The x-ray current generated by the a-Se layer was measured as a function of E(Se). From the current measurement and the estimation of total x-ray energy absorbed in the a-Se, the energy required to create one electron-hole pair (EHP), W, was determined as a function of E(Se). It was found that at the most commonly used E(Se) of 10 V/microm, W was measured as 64 eV. This is considerably higher than the widely accepted typical value of W = 50 eV measured at higher x-ray photon energies (e.g., 50 keV). The dependence of W as a function of E(Se) can be best fitted using the empirical expression of E(Se)-gamma. This relationship is consistent with the results ob...Continue Reading

References

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Citations

Oct 14, 2004·European Radiology·A Noel, F Thibault
Apr 5, 2005·European Radiology·Martin Spahn
Sep 10, 2013·Physica Medica : PM : an International Journal Devoted to the Applications of Physics to Medicine and Biology : Official Journal of the Italian Association of Biomedical Physics (AIFB)·T SakellarisA Pascoal
Feb 22, 2005·Medical Physics·Bo Zhao, Wei Zhao
Jun 12, 2004·Medical Physics·C SchroederB G Fallone
Jan 11, 2011·Journal of Instrumentation : an IOP and SISSA Journal·M UrdanetaS Brock
Jun 6, 2009·Physics in Medicine and Biology·P ToroiM Varjonen

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