Organ radiation doses and lifetime risk of excess cancer for several space shuttle missions

Previously, we presented a methodology for extrapolating a crewmember's skin dose obtained from thermoluminescent dosimetry to organ doses by use of computerized anatomical male and female models. The organs considered are those identified in National Council on Radiation Protection and Measurements (NCRP) Report 98. Using this technique, we have analyzed those Shuttle missions where crew doses ≥5 mGy were observed. Radiation absorbed doses are directly proportional to spacecraft shielding and attitude, orbital altitude, inclination, and mission duration. For 28.5 degree inclination missions, the dominant source of exposure is due to penetrating protons from the South Atlantic Anomaly. Results of Shuttle missions 41-C, 51-D, 51-J, STS-33, STS-31, STS-57, and STS-61 are presented and discussed in detail. Projected lifetime incidence risks of radiation-induced cancer for these missions that were based on NCRP Report 98 may not overestimate risks based on recent findings in cancer incidence studies of Hiroshima and Nagasaki atomic bomb survivors.