The estimation of human tooth enamel in vivo radiation sensitivity to neutron irradiation

Issues

Authors

Khailov A.M.
Medical Radiological Research Centre of RAMS, Obninsk.

Abstract

In the present study MCNP4B simulation code was used to simulate the external neutron irradiation of the human adult mathematical model with pre-defined dental region. It gave the conversion coefficients that relate neutron fluence to the dose absorbed in tooth enamel (molars and pre-molars only) for 20 energy groups of monoenergetic neutrons with energies from 10-9 to 20 MeV for AP, PA, LLAT, RLAT and ISO irradiation geometries. The data presented are intended to provide the basis for connection between EPR dose values and standart protection quantities defined in ICRP Publication 74. The results of the calculations for critical organs were found to be consistent with ICRP data, the discrepancies is generally less than 10% for the fast neutrons. The absorbed dose in enamel was found to depend strongly on the incident neutron energy for neutrons over 10 keV. The dependence of the data on the irradiation geometry was also observed. Lower bound estimates of enamel radiation sensitivity to neutrons were made using obtained coefficients for the secondary photons. Tooth enamel was shown to register at least 10% of the total dose in human body in case of irradiation with pre-fast neutrons in AP irradiation geometry.

Key words
Monte Carlo method, neutron fluence, absorbed dose, molar tooth enamel, EPR dosimetry, irradiation geometry, neutron energy, relative radiation sensitivity of enamel.

References

1. Бочвар И., Клещенко Е., Кушнерева К., Левочкин Ф. Чувствительность эмали зубов человека к альфа-излучению и нейтронам //Атомная энергия. - 1997. - № 5. - С. 380-383.

2. Таблицы физических величин. Справочник /Под ред. акад. И.К. Кикоина. М.: Атомиздат, 1976.

3. Briemeister J.F. MCNP – a general Monte-Carlo n-particle transport code, version 4B. LA-12625. Moscow, 1997.

4. Cheyne V. Average weights of the permanent teeth. Dental Res. 1943. Vol. 22. PP. 181-184.

5. Fattibene P., Anglone M., Pillon M., De Coste V. Tooth enamel dosimetric response to 2.8 MeV neutrons. Nucl. Instrum. Meth. 2003. Vol. 201. PP. 480-490.

6. Hubbell J. and Seltzer S. Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients (version 1.02). Available: http://physics.nist.gov/xaamdi. National Institute of Standards and Technology, Gaithersburg, MD, 2000.

7. International Commission on Radiological Protection. Conversion coefficients for use in radiological protection against external irradiation. ICRP Publication 74. Oxford: Elsevier Science, 1997.

8. International Commission on Radiological Protection. Reference man, anatomical, physiological and metabolic characteristics. ICRP Publication 23. Oxford: Pergamon Press, 1974.

9. Ivannikov A., Tikunov D., Yermakova N. et al. Energy dependence of EPR dose response of tooth enamel to photons: experiment and Monte Carlo simulation. Radiat. Prot. Dosim. 2004. Vol. 108(4). PP. 303-315.

10. Khan R.F., Aslam, Rink W., Boreham D. Electron paramagnetic resonance dose response studies for neutron irradiated human teeth. Nucl. Instrum. Meth. 2004. Vol. 225. PP. 528-534.

11. Khan R.F., Rink W., Boreham D. Dosimetric response evaluation of tooth enamel for accelerator-based neutron irradiation. Radiat. Meas. 2003. Vol. 37. PP. 355-363.

12. Kramer R., Zankl M., Williams G. et al. The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. Health Phys. 2002. Vol. 82(2). PP. 254-255.

13. Tikunov D., Ivannikov A., Trompier F., Herve M. et al. Relative sensitivity of tooth enamel to fission neutrons: Effect of secondary protons. Radiat. Meas. 2005. Vol. 39. PP. 509-514.

14. Zdravkova M., Denis J., Gallez B., Debuyst R. Sensitivity of whole human teeth to fast neutrons and gamma-rays estimated by L-band EPR spectroscopy. Radiat. Meas. 2002. Vol. 35 (6). PP. 603-608.

Full-text article (in Russian)