| A semi-empirical model is derived from operational data collected aboard the International Space Station (ISS) by a tissue equivalent proportional counter (TEPC) and provides an estimate of the absorbed dose equivalent that space-crew may receive from galactic cosmic radiation (GCR) and trapped radiation (TR) sources. The parametric model for GCR exposures correlates the absorbed dose equivalent rate to the cutoff rigidity magnetic shielding parameter at ISS altitudes while the TR parametric model relates the absorbed dose equivalent rate to the mean atmospheric density at the crossing of the South Atlantic Anomaly (SAA). The influences of solar activity, flux asymmetry inside the SAA, detector orientation, and position aboard the ISS on the absorbed dose have been examined. The developed model has successfully predicted the absorbed dose due to GCR and TR exposures within ±10% and ±20%, respectively, over periods of time ranging from a single day to a full mission. In addition, estimates of the protection quantity of effective dose have been simulated using the PHITS Monte Carlo code which allows for the transport of radiation through complex shielding and geometries. The simulations indicate that the dose equivalent measured by the tissue equivalent proportional counter provides a conservative estimate of the effective dose. |
