HML's whole body counter: measuring highly radioactive persons

Area of Science:

• Health Physics
• Nuclear Measurement Science
• Radiation Detection

Background:

• The Human Monitoring Laboratory (HML) monitors individuals for internal radioactive contamination.
• Accidental or intentional releases necessitate robust internal contamination assessment capabilities.
• Existing whole body counting methods require optimization for high contamination scenarios.

Purpose of the Study:

• To reconfigure and recalibrate the whole body counter for high internal contamination events.
• To develop a predictive model for counting efficiency.
• To assess the laboratory's capability for measuring specific radionuclides.

Main Methods:

• Utilized Monte Carlo simulations for calibration.
• Validated simulations with experimental measurements.
• Developed an equation relating counting efficiency to photon energy and phantom-to-detector distance.
• Implemented various counting positions to mitigate dead time effects.

Main Results:

• Achieved counting efficiency predictions within 10% accuracy.
• Developed a functional relationship between efficiency, photon energy, and distance.
• Minimized dead time issues through optimized counting geometries.
• Demonstrated capabilities and limitations using six example nuclides (Co, Co, Y, Ba, Cs, Am).

Conclusions:

• The recalibrated whole body counter is prepared for high internal contamination assessments.
• The developed efficiency equation provides reliable predictions for internal monitoring.
• The HML has enhanced its capacity to detect and quantify internal radioactivity.