Laboratory Investigations

Calcified Tissue International

, Volume 72, Issue 6, pp 745-749

First online:

Volumes From Which Calcium and Phosphorus X-Rays Arise in Electron Probe Emission Microanalysis of Bone: Monte Carlo Simulation

  • P. G. T. HowellAffiliated withDepartment of Prosthetic Dentistry, The Eastman Dental Institute, University College London, Gray’s Inn Road, London WC1X 8LDDepartment of Anatomy, University College London, Gower Street, London WC1E 6BT Email author 
  • , A. BoydeAffiliated withDepartment of Anatomy, University College London, Gower Street, London WC1E 6BT

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Monte Carlo simulations of trajectories for electrons with initial energy of 10 keV through 30 keV were used to map the 3D location of characteristic x-ray photon production for the elements C, P, and Ca until the electrons either escaped as backscattered electrons (BSE) or had insignificant energy. The x-ray production volumes for phosphorus slightly exceed those for calcium, but both greatly exceed the volume through which BSE travel prior to leaving the sample. The x-ray volumes are roughly hemispherical in shape, and the oblate spheroid from which BSE derive occupies only the upper third to half the volume of x-ray generation. Energy-dispersive x-ray emission microanalysis (EDX) may not be secure as a method for the quantitation of BSE images of bone in the scanning electron microscope (SEM). Ca:P elemental ratios from EDX analyses may also be imperfect.


Ca:P ratio EDX BSE SEM Bone Excitation volume Emission volume Microanalysis