Calibration of phoswich-based lung counting system using realistic chest phantom

Area of Science:

• Nuclear physics and instrumentation
• Radiological protection
• In vivo monitoring techniques

Background:

• Phoswich detectors are crucial for in vivo monitoring of actinides.
• Optimizing pulse shape discrimination (PSD) electronics is essential for reducing background noise.
• Low background environments are critical for sensitive radiological measurements.

Purpose of the Study:

• To optimize pulse shape discrimination (PSD) electronics for a phoswich detector system.
• To evaluate the background reduction capabilities of the optimized system.
• To calibrate the phoswich system for in vivo actinide monitoring.

Main Methods:

• Established a phoswich detector system within a low background steel room.
• Optimized various parameters of the pulse shape discrimination (PSD) electronics.
• Calibrated the system using a realistic chest phantom loaded with Americium-241 (Am-241).
• Determined calibration factors for varying chest wall compositions and thicknesses.

Main Results:

• Optimized PSD electronics reduced steel room background from 9.5 to 0.28 cps (17 keV) and 5.8 to 0.3 cps (60 keV).
• The Figure of Merit for the timing spectrum achieved was 3.0.
• True signal loss due to PSD was less than 2%.
• Established calibration factors based on muscle equivalent chest wall thickness.

Conclusions:

• The optimized phoswich detector system with PSD electronics demonstrates significant background reduction for in vivo actinide monitoring.
• The system is calibrated and validated for accurate activity estimation in phantoms.
• This technology enhances capabilities in radiological safety and internal contamination assessment.