Ray-tracing simulation of the radiation dose distribution on the surface of the spherical phantom of the MATROSHKA-R experiment onboard the ISS

• Published in: Life sciences in space research Vol. 21; pp. 65 - 72
• Main Authors: Dobynde, M.I., Effenberger, F., Kartashov, D.A., Shprits, Y.Y., Shurshakov, V.A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.05.2019
• Subjects: Cosmic Radiation; GEANT4 modeling; Humans; International Agencies; MATROSHKA-R; Monte Carlo Method; Phantoms, Imaging; Radiation Dosage; Radiation dose calculation; Radiation Monitoring - instrumentation; Radiation on the ISS; Radiation protection; Space radiation; Space Simulation - methods; Spacecraft - instrumentation; Radiation dose calculation; MATROSHKA-R; Radiation on the ISS; GEANT4 modeling; Radiation protection; Space radiation
• ISSN: 2214-5524; 2214-5532
• DOI: 10.1016/j.lssr.2019.04.001

•We have calculated depth-dose curves, which take into account the shielding composition, for LEO radiation and its components.•We have calculated radiation dose distributions at the surface of the spherical phantom used in the MATROSHKA-R ISS experiment.•The good agreement between the simulation results and the experimental measurements verifies our method for dose calculation at LEO. Space radiation is one of the main concerns for human space flights. The prediction of the radiation dose for the actual spacecraft geometry is very important for the planning of long-duration missions. We present a numerical method for the fast calculation of the radiation dose rate during a space flight. We demonstrate its application for dose calculations during the first and the second sessions of the MATROSHKA-R space experiment with a spherical tissue-equivalent phantom. The main advantage of the method is the short simulation time, so it can be applied for urgent radiation dose calculations for low-Earth orbit space missions. The method uses depth-dose curve and shield-and-composition distribution functions to calculate a radiation dose at the point of interest. The spacecraft geometry is processed into a shield-and-composition distribution function using a ray-tracing method. Depth-dose curves are calculated using the GEANT4 Monte-Carlo code (version 10.00.P02) for a double-layer aluminum-water shielding. Aluminum-water shielding is a good approximation of the real geometry, as water is a good equivalent for biological tissues, and aluminum is the major material of spacecraft bodies. The method is applied to model the dose distribution on the surface of the spherical phantom in the MATROSHKA-R space experiment. The experiment has been carried out onboard the ISS from 2004 to the present. The absorbed dose was determined in 32 points on the phantom's surface. We find a good agreement between the data obtained in the experiment and our calculation results. The simulation method is thus applicable for future radiation dose predictions for low-Earth orbit missions and experiments.