Lung counting: summing techniques to reduce the MDA

Area of Science:

• Nuclear physics and radiation detection.
• Occupational health and safety.
• Environmental monitoring.

Background:

• Recent adoption of lower dose limits (20 mSv) in Canada and globally complicates in vivo detection of radionuclides.
• Natural uranium presents a particular challenge for detection at these new occupational dose limits.
• Existing in vivo counting methods struggle to meet the sensitivity required for monitoring natural uranium exposure.

Purpose of the Study:

• To develop and validate new techniques for reducing the Minimum Detectable Activity (MDA) for in vivo lung counting of natural uranium.
• To enhance the detection capabilities of the Human Monitoring Laboratory for occupational exposure to natural uranium.
• To address the challenges posed by new, lower dose limits on radionuclide detection.

Main Methods:

• Development of two distinct techniques to lower MDA for natural uranium lung counting.
• Technique 1: Summing sequential counts of an individual or spectra of similarly exposed worker groups (collaboration with Cameco).
• Technique 2: Summing photopeaks within an individual spectrum (collaboration with CNEN).

Main Results:

• Technique 1 (group/sequential summing) achieved MDA reductions of up to a factor of three.
• Technique 2 (photopeak summing) achieved MDA reductions of up to a factor of two.
• Both developed techniques demonstrate significant improvements in detecting natural uranium at lower levels.

Conclusions:

• The developed techniques effectively reduce MDA for natural uranium lung counting, aiding compliance with new dose limits.
• These advancements enhance the capability to monitor occupational exposure to natural uranium.
• The Human Monitoring Laboratory has improved its capacity for in vivo radionuclide detection through innovative methods.