Polaris-LAMP: Multi-Modal 3-D Image Reconstruction With a Commercial Gamma-Ray Imager

Abstract

The Polaris-LAMP multi-modal 3D gamma-ray imager is a radiation mapping and imaging platform which uses a commercial-off-the-shelf detector integrated with a contextual sensor localization and mapping platform. The integration of these systems enables a free-moving radiation imaging capability with proximity mapping, coded aperture, and Compton imaging modalities, which can create 3D reconstruction of photon sources from tens of keV to several MeV. Gamma-ray events are recorded using a segmented cadmium zinc telluride detector (Polaris-H Quad by H3D inc.), while scene data is derived from a contextual sensor and computation package developed by Lawrence Berkeley National Laboratory which includes GPS, laser ranging and inertial measurement sensors. An onboard computer uses these inputs to create rapidly-updating pose (10 Hz) and 3D scene estimates using a simultaneous localization and mapping algorithm. The precise gamma-ray event location and timing resolution of the Polaris CZT sensor enables Compton imaging above several hundred keV, while photon sources at lower images are localized using coded aperture imaging techniques. The multi-modal imaging concept enables imaging of diverse radiation sources spanning from the 59 keV emission of 241 Am to the 1.1 and 1.3 MeV lines of 60 Co. This work focuses on the description of the the operational principles of the detector system and demonstrating the 3D imaging performance in a variety of source detection and mapping scenarios. As a proof of concept, we demonstrate mapping complex environments, including both point source and distributed-source environments using proximity, coded aperture, and Compton imaging modalities. Further, we show the successful use of the system to perform measurements in high-background environments through analysis of arrays of uranium hexafluoride cylinders at the Paducah UF6 project site.

Novel Applications of State-of-the-Art Gamma-Ray Imaging Technique: From Nuclear Decommissioning and Radioprotection to Radiological Characterization and Safeguards

“…Research is still ongoing to further improve imaging technology. Nucleco is currently validating a new hardware (LIDAR, odometry camera, on-board robotic system) and software (mapping engine, like Google Carthographer [35]) add-on to fill some gaps the current 2D imaging system has, creating a proper Simultaneous Localization And Mapping (SLAM) system aware of the space all around it (like in [36]). This SLAM-based system will be capable to determine at each timeframe the detector's position and pose (i.e.…”

Ongoing advancement of free-moving radiation imaging and mapping

“…These results were first presented by Pavlovsky et al 7 In some environments, having good imaging fidelity as well as real-time feedback is very helpful for localizing a radioactive source and for providing an operator with understanding of a radiological environment. With the initial intention of supporting safeguards measurements such as item characterization and accountancy, LBNL developed Polaris-LAMP, 13 which comprised of the LAMP contextual sensors and computing coupled to a Polaris-H CZT-based gamma-ray imager developed by H3D. 14 This detector proved useful for identifying radioactive components of vehicles parked on the Fukushima Dai'ichi nuclear power plant site.…”