The technology at the heart of the study, known as needle virtual reconstruction or NVR, addresses a fundamental bottleneck in image-guided interventions. Percutaneous procedures, in which needles are advanced through the skin to reach deep targets such as tumors or bone lesions, are commonly performed under cone-beam CT guidance. Cone-beam CT holds significant advantages over conventional CT in the interventional suite: it avoids the constraints of bore size and gantry orientation, and it integrates seamlessly with real-time fluoroscopy, allowing clinicians to visualize instruments continuously during an intervention. But there is a catch. Most commercially available guidance systems allow operators to plan a needle trajectory on an initial CBCT acquisition and monitor progress using fluoroscopy overlays, yet evaluating the needle’s latest position within the three-dimensional volume requires acquiring an entirely new CBCT scan. Each additional acquisition adds seconds to minutes of procedure time and delivers another dose of ionizing radiation to both patient and operator.

NVR software, marketed as Needle ASSIST with Stereo 3D by GE HealthCare, sidesteps this problem by mathematical triangulation. Instead of a full volumetric rotation, the system needs only two fluoroscopic projections captured with the needle in place. Because the needle’s silhouette appears from two different angles, and because the geometry of the fluoroscopic gantry is precisely known, the software can reconstruct the needle’s three-dimensional position and map it into the coordinate space of the initial planning CBCT. The virtual needle then appears alongside the planned trajectory, giving the operator an immediate, radiation-light assessment of whether the instrument is on course, short of target, or straying toward danger. The workflow relies on two automatically generated views: a so-called bull’s eye view that looks directly down the barrel of the needle to guide entry point and orientation, and a progress view that displays the full needle shaft to track insertion depth.

To validate this approach rigorously, the research team conducted a retrospective single-center cohort study at a large cancer hospital, with institutional review board approval under protocol 16-402. They enrolled consecutive patients who underwent percutaneous image-guided interventions using NVR software between January 2023 and November 2024. The final cohort comprised 40 procedures in 40 cancer patients: 37 biopsies and 3 kyphoplasties, the latter being vertebral augmentation procedures in which cement is delivered into collapsed vertebrae. All spinal interventions followed a transpedicular approach, threading the needle through the bony pedicle of the vertebra, while other procedures used anatomically safe paths selected to avoid critical structures. Every case followed societal guidelines for anticoagulation management and bleeding risk, and procedures were performed under monitored anesthesia care or general anesthesia by an interventional radiologist with more than two decades of experience.

The imaging protocol followed a standardized sequence. Before any needle was inserted, an initial cone-beam CT was acquired using a 200-degree rotational scan at 40 degrees per second over roughly five seconds, capturing between 147 and 244 frames depending on the suite. Variable kVp and mAs settings dynamically compensated for differences in patient anatomy, and the reconstructed three-dimensional volume spanned a 24-centimeter-diameter cylinder in a 512-cubed matrix. The trajectory was planned tableside by defining target and entry points, and the planned line was overlaid on live fluoroscopy. Bone anatomy derived from the initial CBCT was superimposed to confirm accurate registration and flag any patient movement, with tableside adjustments made as needed. After needle insertion, the virtual reconstruction was generated automatically from two fluoroscopic projections, and critically, a final CBCT was acquired as ground truth to validate needle position before the intervention proceeded. It is this final scan that allowed the team to measure, in hindsight, how well the virtual needle matched reality.

The validation methodology was deliberately conservative. The researchers registered the pre-insertion planning CBCT with the final ground-truth CBCT based on bony landmarks, without displaying the virtual reconstruction. They then measured the maximal distance between the virtual needle tip and the actual needle tip on the bull’s eye view using a dedicated imaging workstation. Two authors performed the measurements independently and reached consensus, with a third author arbitrating disagreements. In parallel, they assessed safety agreement: reviewers first confirmed on the final CBCT that all real needle trajectories avoided critical structures, then checked whether the software’s virtual predictions had correctly indicated those same safe paths. The results were unambiguous. The median discrepancy between virtual and actual needle tip positions was 1.3 millimeters, with an interquartile range of 0.9 to 2.2 millimeters, and the virtual reconstructions correctly predicted the safety profile in every case, with no erroneous depiction of a needle touching a critical structure.

Procedural metrics from the study paint a picture of efficient, low-dose practice. The median procedure duration was 57.5 minutes, median fluoroscopy time was 128 seconds, and the median total dose area product, combining fluoroscopy and CBCT, was 28.9 Gy·cm². Technical success, defined as placement of the needle tip within the boundaries of the targeted lesion or bone on the final CBCT, was achieved in 100 percent of cases. For the applicable tumor cases, the median target lesion size was 24 millimeters. The cohort itself skewed older and heavier, with a median age of 71 years and a median body mass index of 26.1, a detail that matters because larger patients typically require higher radiation doses for adequate image quality. Despite this, the reported doses remained within published reference levels for comparable procedures, suggesting that the guidance software did not inflate radiation burden even in technically challenging anatomy.

The broader implications reach beyond the operating suite. Previous research has suggested that virtual needle guidance technologies can meaningfully cut radiation exposure by eliminating the multiple verification CBCT scans traditionally interspersed through needle positioning. One earlier study cited by the authors reported reductions in air kerma and dose area product of 27 percent and 35 percent respectively when such technology replaced repeated volumetric checks. The accuracy figures now reported go further, raising the possibility that even the final confirmation CBCT, acquired after every needle placement in this study, might eventually be dispensable for select cases, with two quick fluoroscopic views providing sufficient reassurance more simply and faster. The authors are careful on this point: eliminating the final CBCT would require further evaluation, including a randomized or controlled comparison, before it could become standard practice. Guidance software of this kind has already found roles in musculoskeletal intervention, endoleak treatment, and thermal ablation, but the new study is distinctive in specifically quantifying reconstruction accuracy against a ground-truth scan.

The study is not without caveats, and the authors lay them out candidly. It was a single-center retrospective analysis spanning a variety of anatomical targets, so multi-institutional validation would strengthen the findings. The absence of a control group means the team cannot definitively attribute reductions in radiation dose or procedure time to the software itself. Accuracy was measured in a two-dimensional plane on the bull’s eye view rather than in full three dimensions, which would offer a more complete picture of reconstruction error. And the operating physician’s substantial experience, more than twenty years of practice, may have influenced fluoroscopy times and radiation doses in ways that might not generalize to less seasoned operators. There is also a commercial relationship to note: two of the authors serve as consultants for GE HealthCare, the manufacturer of the software and imaging systems used in the study, and the research received support in part through a National Institutes of Health cancer center support grant.

Even with those limitations, the study marks a persuasive step toward smarter, leaner image-guided surgery. The vision it sketches is an interventional suite in which a single volumetric scan at the start of a procedure anchors all subsequent navigation, and every subsequent question about needle position is answered with two milliseconds-fast fluoroscopic frames rather than a full rotation of the C-arm. For cancer patients, who often undergo repeated biopsies and ablative procedures over the course of their illness, the cumulative savings in radiation, anesthesia time, and waiting could be substantial. For the clinicians, a trustworthy virtual needle means fewer interruptions, faster workflows, and continuous three-dimensional awareness of where their instrument truly sits relative to vessels, nerves, and bone. If larger controlled studies confirm these results, the humble biopsy needle may soon travel through the body shadowed by a digital twin that is accurate to little more than a millimeter, and the era of confirming positions with repeated scans may give way to one of calculating them.

Subject of Research: Accuracy and safety of virtual needle reconstruction software during cone-beam CT-guided percutaneous procedures in cancer patients

Article Title: Virtual reconstruction to assess needle position during percutaneous procedures performed under cone-beam computed tomography: safety and accuracy

Article References: Geevarghese, R., Kiely, L., Petre, E. N., Solomon, S. B., & Cornelis, F. H. (2026). Virtual reconstruction to assess needle position during percutaneous procedures performed under cone-beam computed tomography: safety and accuracy. CVIR Oncology, 2(1), Article 9. https://doi.org/10.1007/s44343-026-00042-6

Image Credits: AI Generated

DOI: 10.1007/s44343-026-00042-6

Keywords: cone-beam CT, needle virtual reconstruction, interventional radiology, percutaneous biopsy, image-guided procedures, fluoroscopy, radiation dose, cancer, technical success, kyphoplasty, needle guidance, medical imaging

The research, published in the journal Environmental Geochemistry and Health, was conducted by a team from PES College of Engineering in Mandya, ATME College of Engineering in Mysuru and Visvesvaraya Technological University in Belagavi. The researchers collected soil samples from twenty-one quarry sites scattered across the district, a region whose geology is dominated by granitic terrain. Granite is chemically notorious among radiation scientists: it tends to be enriched in the minerals that carry uranium-series and thorium-series isotopes as well as potassium-40, so soils weathered from granitic bedrock typically register activity concentrations well above the global averages for ordinary soils. This geological signature is precisely what the team’s measurements captured.

Quantifying trace radioactivity requires a sensitive analytical instrument, and the study relied on high-purity germanium (HPGe) gamma-ray spectrometry, the workhorse technique of environmental radiometry. HPGe detectors, when cryogenically cooled, resolve the characteristic gamma-ray energies emitted by each decay chain with exquisite precision, allowing researchers to identify individual radionuclides within a mixed sample. By measuring the intensity of gamma lines characteristic of radium-226, thorium-232 and potassium-40, the team computed the activity concentrations of each isotope in becquerels per kilogram — a measure of how many atomic disintegrations occur per second in each kilogram of soil. The mean values they reported were 39.5 Bq/kg for radium-226, 81.5 Bq/kg for thorium-232 and 656 Bq/kg for potassium-40, confirming the influence of the granitic geology, particularly the elevated thorium and potassium content.

These individual numbers become far more informative when combined into composite indices that radiation protection agencies have designed to summarise risk. The researchers calculated the radium equivalent activity, Ra_eq, which weights the three radionuclides according to their respective gamma contributions; it averaged 206.5 Bq/kg, below the widely used ceiling of 370 Bq/kg associated with a dose of 1 mSv per year. They also computed the gamma radiation representative index (Iγr), the external hazard index (Hex) and the internal hazard index (Hin), which came out at averages of 1.52, 0.56 and 0.66 respectively. The two hazard indices both sit below unity, the conventional threshold indicating that the materials would pose no unacceptable radiological risk if used in construction, either outdoors where exposure is external or indoors where radon inhalation and gamma irradiation combine.

The ratios between the three radionuclides tell their own geological story. The team reported average activity concentration ratios of 2.05 for thorium-232 to radium-226, 16.65 for potassium-40 to radium-226 and 8.15 for potassium-40 to thorium-232. A thorium-to-radium ratio above two is characteristic of soils derived from rocks in which thorium-bearing minerals such as monazite accumulate preferentially, a hallmark of many Indian granitic terrains. Such ratios serve as fingerprints that connect surface soil measurements to the deeper petrology of the region, and they help distinguish natural geological enrichment from any anthropogenic contamination, which was not indicated at these sites.

Laboratory spectrometry alone does not capture the full radiological picture, because real-world exposure happens in situ, under open skies and variable conditions. To complement the sample analysis, the team deployed a calibrated ER-709 portable dosimeter at the quarry locations to measure ambient gamma radiation directly. The instrument recorded an average absorbed gamma dose rate of 89.06 nanogray per hour. Converting this absorbed dose into a quantity that health physicists can compare against international exposure standards yields an annual effective dose of approximately 0.11 millisieverts per year — a figure far below the roughly 2.4 millisieverts per year that every human being receives on average from all natural sources, including cosmic rays, food and inhaled radon.

From the dose measurements the researchers extrapolated two widely used risk metrics. The excess lifetime cancer risk, a statistical estimate of the additional lifetime cancer probability attributable to the measured exposure, averaged 0.38 × 10⁻³, meaning an additional cancer risk of roughly one in twenty-six hundred — within the range that international bodies such as the World Health Organization and the International Commission on Radiological Protection consider acceptable for natural background exposure. The team also estimated an annual gonadal dose equivalent of 671.22 microsieverts per year, a quantity relevant to hereditary effects because gonadal tissues are among the most radiation-sensitive in the body. Again, this value remained within the range documented for ordinary terrestrial environments worldwide and did not approach levels of concern.

The findings carry practical significance beyond academic interest. India’s construction industry consumes enormous quantities of crushed granite aggregate, dimension stone and quarry dust, and regulators must decide whether quarry-derived materials can be used safely in dwellings, schools and infrastructure. The study’s hazard indices below unity provide direct evidence that, for the sites examined in Mandya district, these materials do not exceed radiological constraints for building use. Equally important, the work establishes a baseline: because natural radioactivity varies with geology, long-term monitoring programmes need reference data to detect future changes, whether caused by new excavation, land-use shifts or industrial inputs. The authors emphasise that the dataset provides exactly such a foundation for future soil radioactivity monitoring and radiological assessments in the region.

The Mandya results also sit within a growing body of Indian and international literature on naturally occurring radioactive materials. Comparable surveys of granite quarries in the Bangalore rural district of Karnataka, of soils in neighbouring districts and of quarry sites in states such as Tamil Nadu, Punjab and Kerala have documented similar patterns of granitic enrichment, with regional variations driven by local mineralogy. Globally, studies from Egypt, Turkey, Brazil, Bangladesh, Nigeria and China have applied the same battery of indices — Ra_eq, Hex, Hin, Iγr and excess lifetime cancer risk — to quarry soils, building stones and beach sands, creating a common framework for comparing radiological safety across continents. Against that backdrop, Mandya’s quarry soils emerge as geologically distinctive but radiologically unremarkable.

For the workers and residents of Mandya district, the practical message of the study is one of reassurance grounded in careful measurement rather than assumption. Natural radioactivity is inescapable — it emanates from the bedrock beneath our feet, the minerals in our building materials and even the potassium in our own cells — and the relevant question is always whether local levels exceed the thresholds that decades of radiobiological research have established. In this corner of southern India, where ancient granites meet one of the world’s busiest quarrying economies, the answer is a measured no. The radiation written into the stone is real, quantifiable and now well documented, but it remains a modest contributor to the background radiation that all life on Earth has always lived with.

Subject of Research: Assessment of natural radioactivity from radium-226, thorium-232 and potassium-40 in quarry soils of Mandya district, Karnataka, India

Article Title: Assessment of 226Ra, 232Th and 40K in soil with gamma dose rates from quarries of the Mandya district, Karnataka, India

Article References: Nagaraju, R. M., Siddaiah, S. T., Dudda, C., Halligudra, G., & Jayaram, A. K. (2026). Assessment of 226Ra, 232Th and 40K in soil with gamma dose rates from quarries of the Mandya district, Karnataka, India. Environmental Geochemistry and Health, 48(15), Article 598. https://doi.org/10.1007/s10653-026-03470-8

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03470-8

Keywords: natural radioactivity, radium-226, thorium-232, potassium-40, gamma-ray spectrometry, HPGe detector, quarry soils, granite, radiation dose, radiological hazard assessment, Karnataka, environmental radioactivity

The research, conducted by Blessing N. Ben-Festus and Festus Ben of the Centre for Advanced Materials Research and Development at Federal Polytechnic Ede in Nigeria, with Ben also affiliated with the Centre for Nanoengineering and Advanced Materials at the University of Johannesburg, focused on sediments within a tropical river estuarine system in southwestern Nigeria. The fieldwork was carried out in a waterway shaped by seasonal rainfall and runoff, artisanal and urban pressures, and the steady downstream delivery of weathered material from the surrounding landscape. Regions of this kind are often underrepresented in global radiological databases, which historically have emphasized temperate environments, making the new dataset a valuable reference point not only for Nigeria but for comparative assessments of depositional environments worldwide.

Technically, the study relied on gamma-ray spectrometry, the workhorse technique of environmental radiochemistry. Sediment samples collected from the estuary were prepared, sealed to allow radioactive equilibrium to be established, and then quantified using a calibrated sodium iodide detector, a scintillation-based instrument that records the characteristic gamma-ray energies emitted by decaying nuclides. Sodium iodide spectrometers are prized in field-adjacent laboratories for their high detection efficiency and relatively low cost, although they demand careful energy and efficiency calibration to resolve the photopeaks of interest. The authors followed established calibration practice, drawing on the well-documented performance characteristics of 3-inch by 3-inch NaI(Tl) detectors, to convert counts into activity concentrations expressed in becquerels per kilogram, a unit that describes the number of radioactive decays per second in each kilogram of dry sediment.

The measured activity concentrations told a consistent story. Potassium-40, the primordial isotope that has persisted since the formation of the Earth and pervades virtually all crustal material, averaged 490.50 plus or minus 7.66 becquerels per kilogram across the samples. Uranium-238, the head of the uranium decay series, averaged just 5.67 plus or minus 0.20 becquerels per kilogram, and thorium-232, the progenitor of the thorium series, registered 4.81 plus or minus 0.26 becquerels per kilogram. Benchmarked against the reference values published by the United Nations Scientific Committee on the Effects of Atomic Radiation, the potassium result ran about 16.79 percent above the global average, a modest elevation the authors attribute to the potassium-rich minerals weathered from the catchment’s bedrock and soils. By contrast, the uranium and thorium figures sat far below the corresponding global thresholds, at 82.82 percent and 89.31 percent below them, respectively, underscoring how strongly the local geology, rather than industrial contamination, controls the radiological signature of these deposits.

Raw concentrations, however, are only the starting point of a radiological risk assessment. Because potassium-40, uranium-238 and thorium-232 differ in the energy and intensity of the gamma radiation they emit, regulators and researchers combine them into derived indices that better approximate real-world exposure. The study calculated the radium equivalent activity, a composite quantity that weights the three nuclides according to their relative gamma dose contributions, and obtained a mean value of 50.32 becquerels per kilogram, well under the widely cited 370 becquerels per kilogram ceiling that marks the threshold above which structural or land-use restrictions might be considered. This single number already suggests that neither beachcombers nor construction workers handling dredged sediment would encounter unusual radiation fields at the site.

The dose-based indicators reinforce that conclusion. The absorbed gamma dose rate in air at one meter above the sediment surface averaged 26.13 nanogray per hour, translating into an annual effective dose of roughly 0.03 millisievert per year for a member of the public spending typical time near or on the sediments. For context, the global average outdoor terrestrial dose attributable to natural radionuclides is generally estimated at around 0.07 millisievert per year, meaning the Nigerian estuary delivers less than half of that conventional background. The team also evaluated the annual gonadal dose, a quantity used to approximate the genetically significant dose to reproductive organs, obtaining 191.64 microsieverts per year, again comfortably below the internationally recognized screening level of about 300 microsieverts per year. Taken together, these parameters indicate that external exposure pathways linked to the estuary’s sediments pose no significant radiological risk to the surrounding communities.

The findings matter for reasons that extend beyond a single river. Sediments are the memory of a river system: they trap not only radionuclides but also heavy metals, nutrients and pollutants, and their radioactive inventory reflects the interplay of bedrock composition, weathering intensity, grain-size sorting and hydrodynamic energy. In tropical climates, intense rainfall and episodic flooding periodically resuspend and redistribute these deposits, meaning that a baseline established today is the essential yardstick against which future disturbance, whether from mining, dredging, dam construction or land-use change, can be judged. Comparable investigations along the Arvand River in Iran, the Pashur River in Bangladesh, the Ravi River in Pakistan and the coastal wetlands of southern Taiwan have revealed that fluvial radioactivity can vary enormously with geology, and in some industrialized estuaries technogenic nuclides from mining discharges or phosphogypsum releases dominate the picture. Against that backdrop, the low uranium and thorium readings in this Nigerian system signal an environment whose radiological profile remains essentially natural.

The study also contributes methodological value to the radiological sciences. Gamma spectrometry with sodium iodide detectors requires meticulous attention to detection efficiency, coincidence summing effects and source-to-detector geometry, and the growing literature on detector calibration offers practical guidance for laboratories working with modest infrastructure. By demonstrating that credible, standards-aligned hazard assessments can be produced with such instrumentation, the research lowers the barrier for similar monitoring programs in other data-poor tropical basins. The authors acknowledge research assistants Miss Daud Ajarat Olaide and Mr. Adeyeni Tunmise Afolabi for their contributions during the field study, and the work was funded by the Centre for Advanced Materials Research and Development, highlighting the role of institutionally supported, locally grounded science in filling global environmental data gaps.

Looking ahead, the researchers position their dataset as a foundation for longitudinal monitoring. Natural radioactivity is not static: sediments are eroded, redeposited and chemically transformed, and the same estuary measured after a decade of accelerated development could present a different signature. The measured values, now archived in the peer-reviewed literature and available upon reasonable request, give regulators in Osun State and beyond a defensible pre-disturbance benchmark. They also give residents a rare piece of quantified good news: the muds beneath their river, far from being a hidden radiological hazard, are among the quieter sediments on the planet, holding only a whisper of the uranium and thorium that Earth’s crust normally carries, and a dose burden that any international safety authority would judge unremarkable.

Subject of Research: Measurement of natural radionuclide activity concentrations and radiological hazard indices in sediments of a tropical river estuarine system

Article Title: Sediment-associated natural radionuclide and radiological risk indicators in a tropical river estuarine system

Article References: Ben-Festus, B. N., & Ben, F. (2026). Sediment-associated natural radionuclide and radiological risk indicators in a tropical river estuarine system. Environmental Monitoring and Assessment, 198(10), Article 1069. https://doi.org/10.1007/s10661-026-15895-w

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15895-w

Keywords: natural radionuclides, gamma spectrometry, estuarine sediments, radiological risk, potassium-40, uranium-238, thorium-232, tropical river, environmental monitoring, radiation dose, Nigeria, radium equivalent activity