A gamma-ray imaging method for multiple radionuclides and low-activity radioactive sources

Area of Science:

• Nuclear instrumentation and methods
• Image reconstruction algorithms
• Radiation detection and imaging

Background:

• Gamma-ray coded-aperture imaging is crucial for nuclear security and facility decommissioning.
• Imaging artifacts degrade the accuracy of radioactive source intensity and location identification.
• Existing methods struggle with complex environments and low-activity sources.

Purpose of the Study:

• To develop an improved gamma-ray imaging method to reduce artifacts and enhance source localization.
• To integrate energy spectral information for improved multi-source imaging capabilities.
• To validate the method's effectiveness for low-count and complex environment imaging.

Main Methods:

• Proposed a gamma-ray coded-aperture imaging method using primitive and reversed coded functions (PRCF).
• Integrated energy spectral information by selecting characteristic energy intervals for data filtering.
• Determined correction factor ranges via simulation and established energy interval selection criteria through experiments.
• Utilized a CdZnTe pixel detector-based coded-aperture imaging system for experiments.

Main Results:

• The improved PRCF method significantly reduced imaging artifacts compared to the conventional maximum likelihood expectation maximization (MLEM) method.
• Enhanced imaging quality and ensured accurate localization for multiple radioactive sources.
• Demonstrated effective low-count imaging in complex environments using low-activity ¹³⁷Cs and high-activity ²⁴¹Am and ¹³³Ba sources.
• Established criteria for selecting energy interval ranges for different radioactive sources.

Conclusions:

• The improved PRCF method offers superior performance in reducing artifacts and enhancing image quality for gamma-ray imaging.
• The integration of energy spectral information significantly boosts the capability for multi-source and low-count imaging.
• This method provides a viable solution for imaging low-activity radioactive sources in challenging nuclear environments.