Organ/tissue doses measured with solid-state integrating dosemeters in a low-earth-orbit space mission

Organ/tissue doses in a low-earth orbit space mission were measured in the 9th Shuttle/Mir Mission (STS-91) with a real-size-human phantom. Used for radiation measurement were integrating small solid dosemeters including several types of thermoluminescent dosemeters (TLDs), radiophotoluminescent glasses (RPLGs), and plastic nuclear track detectors (PNTDs). These dosemeters were calibrated on ground using heavy charged particle beams and 137Cs γ-rays. Different LET dependencies were found among those TLDs and RPLG. Responses of the selected dosemeters to high-LET particles showed similar tendencies with those of certain biological endpoints such as enzyme inactivation yield, cell survival, and stochastic effects. Accordingly, approximate biological doses were evaluated from the dosemeter values obtained in the space mission. Absorbed doses and dose equivalents were also evaluated by a combination of TLD-Mg2SiO4 and PNTD. The accumulated absorbed dose in this 9.8-days mission ranged from 1.6 mGy to 2.6 mGy and the dose equivalent based on the quality factor of ICRP-1990 recommendation ranged from 3.1 mSv to 5.1 mSv. Effective quality factors were calculated to be between 1.7 and 2.7. High dose equivalent values were obtained at several radiation-sensitive organs/tissues such as lung, stomach, bone marrow, and gonad. The effective dose equivalent (H) was nearly the same as the skin dose equivalent. (author)