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Title: Direct action of radiation on mummified cells : modelling of computed tomography by Monte Carlo algorithms
Author: Wanek, J. F.
ISNI:       0000 0004 5357 8615
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2014
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X-ray imaging is a non-destructive 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. The effects of CT exposure on ancient cells have not been quantitatively examined in the past and may be important for subsequent genetic analysis. To remedy this shortcoming, different Monte Carlo models were developed to simulate X-ray irradiation on ancient cells. Effects of mummification and physical processes were considered by using two sizes of cells and three different phantom tissues that enclosed the investigated cell cluster. This cluster was positioned at the isocentre 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 physical process, CT scans for X-ray spectra of 80 and 120 kVp were simulated. The calculated risk of DNA damage according to the multi-hit, multi-target model revealed that the probability of two DNA hits was pNT = 0.001 with cell size 6x6x10 μm3 (NT6610) and pNT = 0.00033 with cell size 4x4x6 μm3 (NT446) for normal tissue (NT) at 80 kVp. A further decrease in DNA damage was observed with pNT = 0.0006 (NT6610) and pNT = 0.00009 (NT446) at 120 kVp. All values of p are in good agreement with those given by the X-ray risk of cancer. It is concluded that the probability of ancient DNA (aDNA) damage following CT imaging depends on the number and volume of fragments m with paDNA < pNT^m (m ≥ 1). Increasing the number of aDNA fragments m is associated with rapidly decreasing aDNA damage through X-ray imaging.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available