New article published in 12(4A) - ENAN / INAC 2024

Radiometric Characterization of Pandeiros River Basin (Minas Gerais - Brazil)

Paula et al. 

Abstract: This study aimed to establish reference values (RVs) for the total gamma radiation count rate in the Pandeiros River Basin (PRB), Minas Gerais, Brazil, to evaluate the potential of natural radionuclides as tracers for sediment transport. Five stations (S-1–S-5) were designated along the basin, from upstream to downstream, for in situ radiometric measurements. The complexity of PRB sediment dynamics is attributed to land use practices, erosion, and the inactive Pandeiros Small Hydroelectric Power Plant (SHP). Fieldwork campaigns were performed to capture seasonal variability and collect georeferenced data via on-foot surveys and navigation (using a portable spectrometer). Data processing included Geographic Information Systems (GIS), R programming language, and MS Excel. A comparative analysis with previous studies showed low radiation levels in the PRB, with lower and upper thresholds of 31 and 122 counts per second (cps), respectively, and an average of 61 cps. Natural radiation within the basin poses no risks to local communities, with lower and upper thresholds of 0.13 mSv/year and 0.37 mSv/year, respectively, significantly below regulatory limits (1 mSv/year) defined by the National Nuclear Energy Commission (Comissão Nacional de Energia Nuclear - CNEN) and the International Commission on Radiological Protection (ICRP). No substantial evidence of sediment transport was identified through radiometric measurements during the analyzed time intervals. The definition of the RVs for these variables can play an essential role as baselines in future investigations. Read full article.

Assessment of basal TSPO expression and [¹⁸F]DPA-714 biodistribution in healthy mice and post-ischemic brain using PET imaging

Abstract: Positron emission tomography (PET) is an important tool for preclinical studies in small animals, offering real-time insights into biochemical, metabolic, physiological, and functional processes. PET imaging facilitates the evaluation of biological responses and the biodistribution of novel radiolabeled compounds within a single animal, thereby reducing the need for larger animal groups. Specifically, PET imaging with [¹⁸F]DPA-714, a Translocator Protein (TSPO) ligand, has demonstrated significant predictive and prognostic value in diseases associated with neuroinflammation, correlating well with functional outcomes. In this study, the basal expression of TSPO was investigated in vivo in healthy male C57BL/6JUnib mice, aged 6–9 weeks and weighing 20–30 g. PET was employed to monitor the biodistribution of TSPO tracer. Baseline imaging of [¹⁸F]DPA-714 biodistribution was conducted in healthy mice using static scans at post-injection intervals of 0–20, 20–40, 40–60, and 60–80 minutes. To assess TSPO expression in the post-ischemic brain, the mice were divided into healthy and ischemic groups. The ischemic group underwent transient global cerebral ischemia induced by 25 minutes of bilateral common carotid artery occlusion (BCCAO) followed by reperfusion. PET scans were subsequently performed to analyze the cerebral uptake of [¹⁸F]DPA-714. The results confirm that PET is an effective, non-invasive technique for biodistribution studies. Analysis of SUVmax and SUVpeak metrics revealed increased sensitivity for detecting elevated brain uptake following ischemia, underscoring its importance in preclinical neuroinflammation models. Moreover, baseline uptake of [¹⁸F]DPA-714 was observed across multiple organs, reflecting TSPO’s basal expression, as well as its metabolic and clearance pathways. The comparable baseline uptake observed in the brain and muscle highlights its potential as a reliable marker for investigating TSPO-related inflammatory processes. Read full article.