Graphite as a Skin and Epithelium Dosimeter at mammographic energies

• Main Authors: Bradley, D.A., Lam, S.E., Nawi, S.N. Mat, Sani, Siti Fairus Abdul, Ung, Ngie Min, Alzimami, K., Khandaker, M.U., Moradi, F., Taheri, A.
• Format: Article
• Published: Elsevier 2024
• Subjects: QC Physics; R Medicine (General)
• Online Access: http://eprints.um.edu.my/45439/; https://doi.org/10.1016/j.radphyschem.2024.111543

Use is made of 50 mu m high purity graphite foils, investigating the potential of these in evaluation of dose in dermal and epithelial layers, measuring the thermoluminescence yield obtained as a result of irradiation at mammographic energies. In particular the effort supports the ICRU recommendation that skin dose be assessed at a skin depth 0.07 mm, equating to the uniquely mitotically active dermal layer responsible for the replenishment of skin cells. Support for the results of empirical investigation have been sought from Monte Carlo simulations using the TOPAS code. In study of x-rays generated in the 25- to 30 kVp range, the energetic electrons produced in interaction with the graphite have an approximate range of similar to 7 mu m, so that with a stacked graphite layer arrangement dose assessment is provided at 7 mu m, 57 mu m, 107 mu m etc. TL yield results for the first three layers of graphite, covering nominal depths from the surface through to 150 mu m, obtained on a 50 mu m spatial resolution scale, show deposited dose values to be approximately flat to within +/- 5% throughout this depth. The indication is that for irradiations made using x-ray energies of a few tens of keV use of the present graphite layer arrangement can provide estimation of dermal and epithelial dose.