Proposal for a new operational quantity for eye lens photon dosimetry

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Occupational Health

Background:

• Historically, eye lens radiation dose was inadequately measured, relying on whole-body dose limits.
• Recent International Commission on Radiological Protection (ICRP) recommendations lowered occupational exposure limits, increasing the need for precise eye lens dosimetry.
• Existing methods for assessing eye lens radiation dose lack direct measurability.

Purpose of the Study:

• To propose a new, physically measurable operational quantity for eye lens radiation dose.
• To establish D(6)water as a viable alternative to the current Hp(3) quantity.
• To enhance the accuracy and realism of occupational radiation dose assessments for the eye lens.

Main Methods:

• Utilized the Monte Carlo transport code EGSnrc for photon energy simulations.
• Calculated fluence-to-D(6)water conversion coefficients across a wide energy spectrum (0.02 to 10 MeV).
• Avoided the kerma approximation for enhanced calculation accuracy.

Main Results:

• Developed conversion coefficients for the proposed D(6)water quantity.
• Demonstrated that D(6)water accurately represents the absorbed dose to the lens of the eye (Dlens) across the studied energy range.
• Showed D(6)water is a direct, measurable quantity, unlike Hp(3).

Conclusions:

• D(6)water is a suitable and measurable alternative to Hp(3) for eye lens dosimetry.
• The proposed quantity ensures more accurate radiation dose assessment in occupational settings.
• This work supports improved radiation protection standards for the eye lens.