Validation of the photon dose calculation model in the VARSKIN 4 skin dose computer code

Area of Science:

• Medical Physics
• Radiation Dosimetry

Background:

• Accurate skin dose calculation is crucial for radiation protection.
• VARSKIN is a widely used computer code for estimating skin dose rates.
• Validation of updated code versions is essential for reliable dosimetry.

Purpose of the Study:

• To validate the photon dose rate calculation accuracy of the updated VARSKIN 4 computer code.
• To assess the code's performance across various source geometries and radionuclide combinations.
• To compare VARSKIN 4 results with MCNP5 Monte Carlo simulations.

Main Methods:

• Utilized Monte Carlo transport calculations with MCNP5 for reference data.
• Tested VARSKIN 4 with point, disc, sphere, and cylinder source geometries.
• Evaluated scenarios with sources on skin, with absorber, and with air gaps.

Main Results:

• VARSKIN 4 showed good agreement for non-volume (point, disc) sources.
• Volume sources (sphere, cylinder) led to dose rate overestimations up to 2.5 times.
• Poor agreement was observed for air gap scenarios, with consistent overestimations.

Conclusions:

• VARSKIN 4 is adequate for photon dose assessment with point/disc geometries, especially when beta dose dominates.
• Volume source and air gap discrepancies necessitate caution, particularly when doses approach limits.
• Monte Carlo methods may be required for high-accuracy dose assessments in critical scenarios.