Dynamic Gamma-ray Imaging for In Vivo Tracking of Microelement Transport Across Plant-Microbial Systems

The Department of Energy Office of Biological and Environmental Research (DOE BER) Mesoscale to Molecules Bioimaging Technology Program aims to develop new imaging and measurement technology to enable in situ and dynamic imaging across a range of spatial and temporal scales. Various imaging modalities are required to span the complete spatiotemporal landscape for bioenergy and environmental bioimaging needs. The high-resolution gamma-ray spectroscopy, imaging, and sensitivity of new high-purity germanium (HPGe) instruments provide a unique opportunity to complement and enhance these research goals. The HPGe-based Gamma-ray Imager for Plant Research (GIPR) to be developed here will provide non-invasive, in vivo measurements to dynamically track the uptake and distribution of multiple gamma-emitting radioactive elements simultaneously as they move from the soil microbiome into living plants. The hand portable GIPR will utilize commercially available radioisotopes to provide spatial and temporal imaging of plant microelement exchange for the broader scientific community. During Phase I, new gamma-ray imaging hardware and software were developed and evaluated for plant research applications. A weeklong measurement campaign was held at the plant biology laboratories of our University collaborators to assess the viability of two modified imaging systems for dynamic measurements of radioactive elements moving into and within living plants. The results of this campaign were very encouraging, particularly with the coded-aperture imaging modality, and solidified the concept of a prototype GIPR system for the Plant Research community. Phase II will see the manufacture and evolution of several prototype GIPR systems with new advanced gamma-ray imaging modalities to provide vastly improved sensitivity and resolution for Plant Research. These prototype imagers will be used to observe the real-time transport and allocation of important resources in bioenergy- relevant plants and the local microbial community. The Gamma-ray Imager for Plant Research will provide a versatile bioimaging device in a small, portable form factor for the larger scientific community to enable new Plant Science research using commercially available radioisotopes. The technology developed in this project will naturally contribute to other DOE security-related fields including nuclear weapons non-proliferation, treaty verification, nuclear materials holdup, nuclear safeguards, and diagnostics.