Radiation and Environmental Biophysics

, Volume 52, Issue 3, pp 397–410

Direct action of radiation on mummified cells: modeling of computed tomography by Monte Carlo algorithms

  • Johann Wanek
  • Robert Speller
  • Frank Jakobus Rühli
Original Paper

DOI: 10.1007/s00411-013-0471-z

Cite this article as:
Wanek, J., Speller, R. & Rühli, F.J. Radiat Environ Biophys (2013) 52: 397. doi:10.1007/s00411-013-0471-z

Abstract

X-ray imaging is a nondestructive and preferred method in paleopathology to reconstruct the history of ancient diseases. Sophisticated imaging technologies such as computed tomography (CT) have become common for the investigation of skeletal disorders in human remains. Researchers have investigated the impact of ionizing radiation on living cells, but never on ancient cells in dry tissue. The effects of CT exposure on ancient cells have not been examined in the past and may be important for subsequent genetic analysis. To remedy this shortcoming, we developed different Monte Carlo models to simulate X-ray irradiation on ancient cells. Effects of mummification were considered by using two sizes of cells and three different phantom tissues, which enclosed the investigated cell cluster. This cluster was positioned at the isocenter of a CT scanner model, where the cell hit probabilities P(0,1,…, n) were calculated according to the Poisson distribution. To study the impact of the dominant physics process, CT scans for X-ray spectra of 80 and 120 kVp were simulated. Comparison between normal and dry tissue phantoms revealed that the probability of unaffected cells increased by 21 % following cell shrinkage for 80 kVp, while for 120 kVp, a further increase of unaffected cells of 23 % was observed. Consequently, cell shrinkage caused by dehydration decreased the impact of X-ray radiation on mummified cells significantly. Moreover, backscattered electrons in cortical bone protected deeper-lying ancient cells from radiation damage at 80 kVp X-rays.

Keywords

CT imagingTarget theoryCell shrinkageMonte Carlo simulationAncient DNA

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Johann Wanek
    • 1
    • 2
  • Robert Speller
    • 2
  • Frank Jakobus Rühli
    • 1
  1. 1.Centre for Evolutionary Medicine, Institute of AnatomyUniversity of ZürichZurichSwitzerland
  2. 2.Department of Medical Physics and BioengineeringUniversity College LondonLondonUK