Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU...

Area of Science:

• Space Science
• Radiation Dosimetry
• Astroparticle Physics

Background:

• Space missions expose astronauts to significant levels of cosmic radiation.
• Accurate estimation of absorbed dose and dose equivalent is crucial for astronaut safety.
• Previous methods may not fully account for the complexities of space radiation environments.

Purpose of the Study:

• To estimate absorbed-dose and dose-equivalent rates for astronauts in spacecraft.
• To evaluate the accuracy of dose conversion coefficients derived from computational models.
• To investigate the discrepancy between effective dose and effective dose equivalent in space dosimetry.

Main Methods:

• Utilized the particle and heavy ion transport code system PHITS for calculations.
• Employed male and female adult reference computational phantoms (ICRP/ICRU).
• Calculated cosmic-ray fluxes inside and near spacecraft using simplified geometries.
• Verified results against experimental data from inside and outside spacecraft.

Main Results:

• Fluence-to-dose conversion coefficients were multiplied by cosmic-ray fluxes to estimate dose rates.
• Calculations showed effective doses are significantly greater than effective dose equivalents for astronauts.
• This discrepancy is attributed to numerical incompatibility between radiation quality and weighting factors.

Conclusions:

• The study demonstrates the utility of dose conversion coefficients for accurate space dosimetry.
• PHITS code and computational phantoms provide reliable tools for space radiation assessment.
• Understanding the difference between effective dose and dose equivalent is vital for radiation protection in space.