A new paradigm in personal dosimetry using LiF:Mg,Cu,P

Area of Science:

• Health Physics
• Radiation Detection and Measurement
• Dosimetry Systems

Background:

• The U.S. Navy has monitored personnel for occupational radiation exposure since 1947.
• Early monitoring utilized film badges, transitioning to thermoluminescence dosemeters (TLDs) in 1973.
• A 1994 research project aimed to develop a state-of-the-art TLD system for large-scale dosimetry processing.

Purpose of the Study:

• To develop an advanced thermoluminescent dosimetry system for the U.S. Navy.
• To improve the accuracy, precision, and sensitivity of occupational radiation monitoring.
• To implement a systems approach for large-scale dosimetry processing.

Main Methods:

• Replaced LiF:Mg,Ti TLD elements with more sensitive LiF:Mg,Cu,P elements.
• Optimized dosemeter filters for gamma and X-ray energy discrimination using Monte Carlo (MCNP) modeling.
• Implemented neural-network based algorithms (back propagation and functional link) for dose calculation.

Main Results:

• Achieved significant increases in sensitivity, linearity, and reduced fading with LiF:Mg,Cu,P elements.
• Improved accuracy and precision in radiation energy discrimination through optimized filter design.
• Neural network algorithms provided comparable and effective dose calculation results.

Conclusions:

• The developed TLD system represents a significant advancement in occupational radiation monitoring for the U.S. Navy.
• The integration of new materials, optimized filters, and advanced algorithms enhances the reliability of radiation dose assessment.
• Operational aspects such as background subtraction, control dosemeter selection, reader optimization, calibration, and heating profiles were crucial for system implementation.