Improving the detection limit in lung counting with a segmented HPGe detector.

Area of Science:

• Nuclear instrumentation and radiation detection.
• Medical physics and computational modeling.
• Environmental and occupational health physics.

Background:

• Lung counting applications require sensitive detection of internal radioactive contamination.
• Compton scattering from internal and external sources creates background noise in High-Purity Germanium (HPGe) detector spectra.
• Minimizing background is crucial for accurate assessment of inhaled radionuclides like Americium-241 (Am-241).

Purpose of the Study:

• To investigate the effectiveness of a segmented HPGe detector with active and passive shielding in reducing background events for lung counting.
• To evaluate the impact of this configuration on the Minimum Detectable Activity (MDA) compared to traditional single-crystal HPGe detectors.
• To assess the suitability of the proposed detector system for field measurements.

Main Methods:

• Simulations were performed using the Geant4 toolkit.
• Eight different segmented HPGe detector models with various shielding configurations were tested.
• Inhaled Am-241 activity was simulated in the lungs of an ICRP adult reference computational phantom.
• The reduction in MDA for internal and external sources was calculated and compared.

Main Results:

• The segmented HPGe detector combined with active shielding demonstrated a significant reduction in background events.
• A reduction in MDA of up to 30% for internal sources and 66% for external sources was achieved.
• The proposed detector configuration effectively lowers the detection limit and/or measurement time.

Conclusions:

• The segmented HPGe detector with active shielding is a promising advancement for lung counting applications.
• This technology can improve the accuracy and efficiency of monitoring internal radioactive contamination.
• The system is particularly advantageous for mobile or field-based radiation monitoring scenarios.