Dose and Radiation Effects Assessment Distribution Code

This model allows the user to evaluate the Effective Dose and the Ambient Dose Equivalent (see ICRP 116 Glossary, 2010) received by human tissue behind a shielding material, which can be natural or artificial, caused by ionizing radiations present outside the Earth magnetosphere.

The user defines different input parameters such as the shielding properties, including number of layers, atomic composition and thickness of each layer, the period of time to consider and the distance from the Sun. The user may also define the spatial scaling factor exponent (Smart and Shea, 2003).

The model is based on the Bethe-Bloch equation for the energy released in the material by charged particles assessment (Sternheimer et al., 1984; Groom, 1993). The information concerning particles flux is based upon data collected by some recent satellites, such as ACE and two spacecrafts of the GOES constellation (ACE website; GOES website). The user may also evaluate the Galactic Cosmic Ray and Anomalous Cosmic Ray fluxes through the Nymmik model (ISO TS 15390, 2004; Nymmik et al., 1992, 1996), where a prediction model is used in case of future dates inside a suitable sun-spot cycle (Hathaway, 1994).

The dose values are calculated with two method: the Effective Dose is evaluated using specific conversion fluence-to-dose coefficients (ICRP 116, 2010; Sato et al., 2009, 2010), while the Ambient Dose Equivalent is evaluated using the ICRU Sphere definition (see ICRU report 33 or IAEA Glossary). The first method provides different types of exposure, where the isotropic exposure is recommended as the most conservative condition (see ICRP 116, 2010).

Finally, with this simplified model the user may assess the radiation effects on targets outside the Earth magnetosphere, either during journey inside a spacecraft or during the settlement on different celestial bodies such as planned by future world-wide space agencies missions.

Main input parameters
in cm^2
in cm
in AU
such that F=F(1AU)*R^beta
See references for further explanations
See references for further explanations
See references for further explanations
See references for further explanations

References

  • ICRP, 2010. Conversion Coefficients for Radiological Protection Quantities for External Radiation Exposures. ICRP Publication 116, Ann. ICRP 40(2–5), doi: 10.1016/j.icrp.2011.10.001
  • ICRU - International Commission On Radiation Units And Measurements, Radiation Quantities and Units, ICRU Report 33, ICRU, Bethesda (1980), doi: 10.1002/jlcr.2580180918
  • IAEA website Glossary
  • D.F. Smart and M.A. Shea, Comment on Estimating the Solar Proton Environmen that May Affect Mars Missions, Adv. Space Res., 31, 45-50, 2003, doi: 10.1016/S0273-1177(02)00655-5
  • R.M. Sternheimer, M.J. Berger, S.M. Seltzer, Density Effect for the Ionization Loss of Charged Particles in Various Substances, Atomic Data and Nuclear Data Tables, 30, 261-271, 1984, doi: 10.1016/0092-640X(84)90002-0
  • D. Groom, Energy Loss in Matter by Heavy Particles, Particle Data Group Notes, 8 December 1993, Lawrence Berkeley Laboratory
  • ACE satellite website
  • GOES satellites website
  • ISO TS 15390, Space Environment (Natural and Artificial) - Galactic Cosmic Ray Model, ref. num. ISO 15390:2004(E), 2004, download
  • R.A. Nymmik, M.I. Panasuk, T.I. Pervaja and A.A. Suslov, A Model of Galactic Cosmic Ray Fluxes, Nucl. Tracks Radiat. Meas., 20, 3, 427-429, 1992, doi: 10.1016/1359-0189(92)90028-T
  • R.A. Nymmik, M.I. Panasuk and A.A. Suslov, Galactic Cosmic Ray Flux Simulation and Prediction, Adv. Space Res., 17, 2, 219-230, 1996, doi: 10.1016/0273-1177(95)00508-C
  • D.H. Hathaway, R.M. Wilson and E.J. Reichmann, The Shape of the Sunspot Cycle, Solar Physics, 151, 177-190, 1994, doi: 10.1007/BF00654090
  • T. Sato, A. Endo, M. Zankl, N. Petoussi-Henns and K. Niita, Fluence-to- Dose Conversion Coefficients for Neutrons and Protons Calculated Using the PHITS Code and ICRP/ICRU Adult Reference Computational Phantoms, Phys. Med. Biol., 54, 1997–2014, 2009, doi: 10.1088/0031-9155/54/7/009
  • T. Sato, A. Endo and K. Niita, Fluence-to-Dose Conversion Coefficients for Heavy Ions Calculated Using the PHITS Code and the ICRP/ICRU Adult Reference Computational Phantoms, Phys. Med. Biol., 55, 2235–2246, 2010, doi: 10.1088/0031-9155/55/8/008

For further explanations or information, please write to emanuele.cazzola@wis.kuleuven.be

Acknowledgement

The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement eHeroes (project n° 284461, www.eheroes.eu)