Portable X-ray Research Articles

X- ray experimental set-up for in-vitro nail test

In this investigation, the elements Ca and S were evaluated in a single nail clipping using compact and portable X-ray spectrometer model X-123 SDD with Ag target. Experimental conditions for current, voltage and excitation time were investigated. These analyses can be useful for a variety of applications, including nutritional and medical diagnosis, such as, the evaluation of bone dysfunctions by measurement of Ca (bone decalcification) and S for nutrition evaluations (collagen production). This analysis offers some benefits comparatively to blood and serum analyses, such as, non-invasive collection, fast analyses (minutes) and low cost. In addition, nail clippings are simple to obtain, easy to store, and easy to transport. This pilot study show a positive expectation for clinical application using in-vitro nail test.

An interdisciplinary approach to the study of kiln firing: a case study from the Campus Galli open-air museum (southern Germany)

Pottery kilns are a common feature in the archaeological record of different periods. However, these pyrotechnological installations are still seldom the target of interdisciplinary investigations. To fill this gap in our knowledge, an updraft kiln firing experiment was run at the Campus Galli open-air museum (southern Germany) by a team consisting of experimental archaeologists, material scientists, geoarchaeologists, and palaeobotanists. The entire process from the preparation of the raw materials to the firing and opening of the kiln was carefully recorded with a particular focus on the study of the raw materials used for pottery making, as well as on fuel usage. The temperatures were monitored by thermocouples placed at different positions in the combustion and firing chambers. In addition, thermocouples were installed within the kiln wall to measure the temperature distribution inside the structure itself. Unfired raw materials as well as controlled and experimentally thermally altered ceramic samples were then characterised with an integrated analysis including ceramic petrography, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and portable X-ray fluorescence (pXRF). Our work provides data about mineralogical and microstructural developments in both pottery kiln structures and the ceramics produced in this type of installations. This is helpful to discuss the limits and potential of various scientific analyses commonly used in ancient ceramic pyrotechnological studies. Overall, our work contributes to a better understanding of updraft kiln technology and offers guidelines on how to address the study of this type of pyrotechnological installations using interdisciplinary research strategies.

Using pXRF and Vis-NIR for characterizing diagnostic horizons of fine-textured podzolic soils in subtropical forests

Proximal soil sensing is a promising tool to quantify soil properties through spectral data and machine learning algorithms for application in pedological investigations. However, the relationship between pedological characteristics and sensor signals is difficult to be elucidated with machine learning models. This study aimed to establish direct linkages between pedological features and data from proximal sensors, namely portable X-ray fluorescence spectrometry (pXRF) and visible and near-infrared spectroscopy (Vis-NIR). Ten podzolic soil profiles, including seven Spodosols, two Ultisols, and one Inceptisol, were described and sampled from Central Taiwan. Principal component analysis (PCA) and k-means clustering method revealed that the major variances of the pXRF were affected by the amounts of spodic materials and organic carbon derived from plant debris. For Vis-NIR, a remarkable absorption of Fe-oxides was observed in the B horizons, and the major variations of Vis-NIR spectra extracted by PCA represented the influence of metal-complexed organic carbon and clay. The principal components (PC) of pXRF and Vis-NIR can be used to separate soil horizons, especially the E horizons were clearly separated as indicated by its high user’s and producer’s accuracies. However, the B and C horizons were poorly separated by the PCs and k-means clustering method. Moreover, the PCs can be used directly to predict the nanocrystalline Fe and Al and the optical density of the oxalate extract. Ten soil profiles were classified based on the predicted values, and nine out of ten soil profiles were in agreement with their classification using chemical extractions. The proposed pXRF and Vis-NIR approaches predicted the chemical criteria of diagnostic horizons and facilitated fast determination of Spodosols.

In-Field Obsidian XRF Analysis of Sites in the Lion Mountain Area and Gallinas Mountains of West-Central New Mexico

ABSTRACT The Gallinas Mountains of west-central New Mexico were home to agriculturalists between ca. a.d. 850 and 1450. Ongoing research of the Lion Mountain Archaeology Project (LMAP) has allowed for in-field analysis of surface obsidian artifacts via portable handheld energy dispersive X-ray fluorescence spectrometry (ED-XRF). Influenced by principles of preservation archaeology and the archaeological repository curation crisis, the LMAP has sought to design and conduct field research to gather the most data with the least amount of impact to sites. Non-destructive in-field analysis via portable handheld ED-XRF subscribes to these goals while also providing answers to significant questions about human behavior. Results show that variable patterns of obsidian source utilization and procurement strategies existed both through time and between contemporaneous populations. These results are indicative of a shifting system of exchange and social interaction between residents of the region and surrounding areas during the Ancestral Pueblo occupation of the area.

Methodologies for the Characterization and Identification of Natural Atacamite as a Pigment in Andean Colonial Painting

Painting materials used in Spanish American Colonial art comprised pigments and binders from European origin as well as those that were already known in pre-Hispanic times. In recent years, we have identified for the first time the mineral atacamite, a basic copper chloride (Cu2Cl(OH)3), in Andean Colonial art pieces (Viceroyalty of Peru, 16th–18th centuries). This work proposes a methodology based on a multitechnical approach to identify and establish the origin (natural or synthetic) of the atacamite pigment in Andean cultural heritage objects. Optical microscopy (OM), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), portable X-ray fluorescence spectroscopy (pXRF), attenuated total reflection infrared spectroscopy (FTIR-ATR), micro-Raman spectroscopy, and wide-angle X-ray scattering (WAXS) were applied to analyse green pigments from the altarpiece of the Church of Ancoraimes, atacamite mineral samples from Chile, and atacamite obtained as a secondary product from traditional recipes used to produce verdigris, a copper acetate. Viride salsum by Teófilo Presbítero (SXII) and the Spanish translation by Andrés de Laguna (1566) of “De Materia Médica” from Dioscorides are both texts that include recipes involving the use of metallic copper as a starting material. These studies will contribute to the history of Spanish American Colonial art and to the knowledge on technological capacities and skills in the Andean region during this period.

Testing the suitability of portable X-Ray Fluorescence (pXRF) analysis of dried herbarium specimens to detect Ni hyperaccumulators in South Africa

Metal hyperaccumulators accumulate particular metals or metalloids in their leaves to concentrations hundreds or thousands of times greater than is normal for most plants. Globally, Ni is the most often hyperaccumulated metal, with 532 hyperaccumulator species documented to date. Hyperaccumulators have attracted much attention as potential candidates for green technologies, including phytoremediation and agromining. In South Africa, six serpentinite-associated plants in the genera Berkheya and Senecio hyperaccumulate Ni (to > 0.1% of leaf tissue dry weight). It is surprising that only six of about 70 Berkheya and 290 Senecio species native to South Africa hyperaccumulate Ni, given about ∼10–20% of taxa from each genus occur on serpentinite. While it is costly and time consuming to field collect and chemically analyze leaves of all species in these genera, a novel method (portable X-Ray Fluorescence or pXRF analysis of herbarium specimens) allows for rapid (100 s of specimens/day) and non-destructive measurement of Ni in dry herbarium specimens. We tested the accuracy of this approach on known Ni hyperaccumulators vouchered at two South African herbaria (C.E. Moss Herbarium (J) of the University of the Witwatersrand and A.P. Goossens Herbarium (PUC) from North-West University). While the absolute concentrations of Ni determined by ICP-MS and pXRF were not always directly in agreement, we had 100% success in confirming those that were known to hyperaccumulate Ni with those that did not. We propose pXRF as a cheap, effective, and efficient approach to rapidly screen herbarium specimens across South Africa to discover additional metal hyperaccumulators for much-needed remediation purposes.

O75 (not presented) Evaluation of a portable X-ray fluorescence device for a sustainable mineral nutrition in dairy herds

O75 (not presented) Evaluation of a portable X-ray fluorescence device for a sustainable mineral nutrition in dairy herds

Multi-analytical techniques for characterization of ancient Egyptian pottery objects from Cairo University excavations at Saqqara

Archaeological pottery shows various forms of deterioration and degradation. This research aims to determine the chemical composition and diagnose the damage manifestations of three pottery vessels from the archaeological site of Saqqara. The AutoCAD, digital microscope, X-ray diffraction, polarized microscope, portable X-ray fluorescence, and scanning electron microscopy are utilized to understand the preservation status of pottery vessels. According to the investigation’s findings, the chosen vessels had cracks, accumulated dirt, missing parts, peeling of the slip layer, and black deposits. The X-ray diffraction analysis showed that Albite, Anorthite, Wollastonite, Quartz, Calcite, and Hematite are the primary constituents of the vessels. However, the polarized microscope showed the plagioclase feldspar, indicating that the Nile clay is the source of the raw clay and that the temperature rose above 800 °C. Portable X-ray fluorescence and scanning electron microscopy revealed different concentrations of Si, Fe, and Ca, which are the main pottery components. In addition to the presence of high concentrations of chloride salts. There is no doubt that this will help to preserve the archaeological pottery in future studies.

Determining the Provenance of Traded Wildlife in the Philippines.

The illegal wildlife trade is a significant threat to global biodiversity, often targeting already threatened species. In combating the trade, it is critical to know the provenance of the traded animal or part to facilitate targeted conservation actions, such as education and enforcement. Here, we present and compare two methods, portable X-ray fluorescence (pXRF) and stable isotope analysis (SIA), to determine both the geographic and source provenance (captive or wild) of traded animals and their parts. Using three critically endangered, frequently illegally traded Philippine species, the Palawan forest turtle (Siebenrockiella leytensis), the Philippine cockatoo (Cacatua haematuropygia), and the Philippine pangolin (Manis culionensisis), we demonstrate that using these methods, we can more accurately assign provenance using pXRF data (x¯ = 83%) than SIA data (x¯ = 47%). Our results indicate that these methods provide a valuable forensic tool that can be used in combating the illegal wildlife trade.

Penetrating combat-related thoracic trauma (review)

Objective — to study in detail the mechanisms and to investigate the imaging manifestations of combat-related penetrating thoracic injuries.
 Materials and methods. To perform the work, a literature search was provided according to the criterion «Thoracic penetrating combat-related trauma». 32 literary sources were selected for this request. Frag­ments of the clinical experience described in the literature according to the selected sources were illustrated by our own clinical cases of patients who were treated in Kharkiv medical institutions in 2022 for penetrating combat-related thoracic injuries.
 Results and discussion. Among victims who received chest injuries, polytrauma was most often diagnosed, complicated by several mechanisms of injury associated with penetrating, blunt, and explosive injuries. Pneumothorax and pulmonary contusion were the most common chest injuries. Thoracic injuries, thoracic vascular injuries, and lung ruptures were associated with the highest mortality rates, whereas pulmonary contusions, pneumothorax, and chest wall injuries were associated with relatively lower mortality rates. Chest X-ray is the first-line imaging method during the initial assessment of thoracic trauma in combat and non-combat situations. Such an examination is particularly important in polytrauma situations where multiple fatal injuries can be rapidly diagnosed in order to rapidly triage and include such an injury in the initial evaluation. Tension pneumothorax, large hemothorax, chest fragmentation, and some other lesions can be quickly diagnosed with a portable chest X-ray. Computed tomography (CT) of the chest is an important component of the comprehensive trauma evaluation, which allows to diagnose life-threatening injuries in hemodynamically stable patients with suspected multiple injuries not identified on chest X-ray. Chest CT detects 20 % more pathologies compared to chest X-ray.
 Conclusions. Combat-related thoracic trauma continues to be a significant contributor to the mortality rates of those injured in military operations. A clear injury pattern and atypical imaging manifestations of thoracic trauma are important to recognize at an early stage because of the acuteness of this category of patients and the impact of an accurate diagnosis on clinical management. Chest X-ray remains the main diagnostic tool. However, in modern and well-equipped institutions, chest CT, video-assisted thoracoscopy, and ultrasound scanning of the abdominal and chest cavity play an important role in the diagnosis of thoracic trauma. Quick and high-quality diagnosis and treatment are possible only in direct cooperation between surgeons and radiologists.

In Situ Study of the Painting “Hiroshima I” (1958) by Werner Tübke (1929–2004)

This article presents the results of technical studies of the oil painting by the artist of German origin Werner Tübke “Hiroshima I” (1958). The creative heritage of this author has not been studied enough and represents scattered data on the technology of painting and artistic techniques. The aim of this work was to determine the art materials and painting technology described in his diaries, using the example of his only painting represented in Russia: “Hiroshima I”. For this purpose, an in situ approach was implemented using some simple museum instrumentations—UV-induced visible luminescence, infrared reflectography (IRR), radiography, portable X-ray fluorescence (XRF), Fourier transform Infrared spectroscopy (FT-IR), and polarizing microscopy using microprobes. As a result, the pigment composition of the painting layers could be determined, the painting technology refined, and a previously unknown hidden portrait of Werner Tübke’s father revealed.

Revisiting the Côte d’Ivoire tektite strewn field

The tektites of the Côte d’Ivoire strewn field, called “ivorites”, come from the Bosumtwi meteorite impact crater formed 1.07 Ma ago in Ghana. Unlike other tektite strewn fields in the world, this tektite strewn field has remained under-explored after the pioneering works of A. Lacroix in the 1930s who reported the first tektites on the African continent, followed by a few explorers in the 1960s. To date, the geochemical properties of only slightly more than 20 ivorites have been measured, while there are potentially thousands to be discovered by analogy with other strewn fields. Based on these earlier works, the ivorites strewn field is considered to form an ellipse of about 1500 km2 around the town of Ouellé and Daoukro, setting apart three isolated finds. We conducted six exploratory missions in Côte d’Ivoire between 2019 and 2023 and report 174 new finds. These discoveries are mostly within the known limits of the strewn field, but several discoveries outside these limits extend the strewn field to an area of 4100 km2. The furthest discovery considered to be part of the strewn field is more than 45 km south of its previous limits. These new ivorites present various shapes (teardrops, dumbbells, spheres, ellipsoids) with masses ranging from 1 to 96 g. A geochemical analysis of 172 of these ivorites was performed using a portable X-ray fluorescence spectrometer. In addition, 87 ivorites (unknown locations), made available by the SODEMI museum (Côte d’Ivoire's governmental mining development company in Abidjan) were also analyzed. Their geochemical composition is clearly distinct from that of tektites from other strewn fields. However, these analyses reveal a more variable chemical composition than the apparent homogeneity previously inferred from a small number of specimens. The magnetic susceptibility of these tektites, measured with the SM150 device, is homogeneous and the small variations are essentially related to the iron content. The measured density of ivorites is comparable to the pore-free densities estimated from their chemical composition, implying that the abundant vesicles commonly observed at the surface, associated with bubbles and degassing of the silicate melt, are not present in the interior.

Fluvial Morphology as a Driver of Lead and Zinc Geochemical Dispersion at a Catchment Scale

Metal-mining exploitation has caused ecosystem degradation worldwide. Legacy wastes are often concentrated around former mines where monitoring and research works are mostly focused. Geochemical and physical weathering can affect metal-enriched sediment locations and their capacity to release metals at a catchment scale. This study investigated how fluvial geomorphology and soil geochemistry drive zinc and lead dispersion along the Nant Cwmnewyddion (Wales, UK). Sediments from different locations were sampled for geochemical and mineralogical investigations (portable X-ray fluorescence, scanning electron microscope, X-ray diffraction, and electron microprobe analysis). The suspended sediment fluxes in the streamwater were estimated at different streamflows to quantify the metal dispersion. Topographical and slope analysis allowed us to link sediment erosion with the exposure of primary sulphide minerals in the headwater. Zinc and lead entered the streamwater as aqueous phases or as suspended sediments. Secondary sources were localised in depositional stream areas due to topographical obstruction and a decrease in stream gradient. Sediment zinc and lead concentrations were lower in depositional areas and associated with Fe-oxide or phyllosilicates. Streamwater zinc and lead fluxes highlighted their mobility under high-flow conditions. This multi-disciplinary approach stressed the impact of the headwater mining work on the downstream catchment and provided a low-cost strategy to target sediment sampling via geomorphological observations.

Lead exposure of mainland Australia's top avian predator

Lead (Pb) toxicity, through ingestion of lead ammunition in carcasses, is a threat to scavenging birds worldwide, but has received little attention in Australia. We analyzed lead exposure in the wedge-tailed eagle (Aquila audax), the largest raptor species found in mainland Australia and a facultative scavenger. Eagle carcasses were collected opportunistically throughout south-eastern mainland Australia between 1996 and 2022. Lead concentrations were measured in bone samples from 62 animals via portable X-ray fluorescence (XRF). Lead was detected (concentration >1 ppm) in 84% (n = 52) of the bone samples. The mean lead concentration of birds in which lead was detected was 9.10 ppm (±SE 1.66). Bone lead concentrations were elevated (10–20 ppm) in 12.9% of samples, and severe (>20 ppm) in 4.8% of samples. These proportions are moderately higher than equivalent data for the same species from the island of Tasmania, and are comparable to data from threatened eagle species from other continents. Lead exposure at these levels is likely to have negative impacts on wedge-tailed eagles at the level of the individual and perhaps at a population level. Our results suggest that studies of lead exposure in other Australian avian scavenger species are warranted.

Simultaneous combined XRF-XRD analysis of geological sample: New methodological approach for on-site analysis on New-Caledonian Ni-rich harzburgite

There is a growing interest in on-site, real-time analytical solutions for mining and environmental projects to characterize large areas and/or volumes of raw materials that are sometimes highly heterogeneous in terms of elemental distribution and mineralogy. Several fast and cost-effective methods are used for rapid on-site screening and real-time chemical and mineralogical characterization, such as portable X-ray fluorescence (pXRF) and X-ray diffraction (pXRD). However, these methods are not always applicable due to limitations in the detection and quantification of light elements (Mg, Al, Si) for pXRF or complex or minor minerals for pXRD, whose results need to be supported by laboratory analysis.This study presents a new methodological approach for in situ rapid chemical and mineralogical characterization of samples, based on the use of a transportable instrument (called ID2B) that allows, in a single acquisition step, a combined XRD-XRF analysis to identify and quantify the chemical elements and their associated minerals. The HI0 harzburgite sample from New Caledonia used to evaluate the data was analyzed in the laboratory (SEM-EDS, EPMA, XRF and XRD) and with the ID2B instrument to highlight the potential of our new methodology. In order to demonstrate the interest of using the ID2B combined XRF-XRD analysis approach directly in the field, where sample preparation is not always easy to implement, this comparison was made on the same sample (HI0), prepared in two different ways, either as a powderized (optimal preparation) or as-sawn (unprepared) sample. After automated processing of the combined XRF-XRD datasets acquired with the ID2B instrument, the chemical elements and mineralogical phases identified on both the powder and as-sawn samples are identical to the laboratory analyses.The chemical proportions calculated from the combined XRF-XRD data sets are also close to the laboratory XRF analysis with relative errors <5 % for Al, Mg and Si and even closer for Ca, Cr, Mn, Ni and Fe. The variability in the calculated chemical proportions is attributed to the sample heterogeneity highlighted by the mineral proportions that vary slightly between the laboratory XRD and XRD ID2B analyses of the powder, and more pronounced for the as-sawn XRD ID2B analysis. These observations show that the combined XRF-XRD approach performed on powder and as-sawn samples provides accurate chemical and mineralogical results to those obtained in the laboratory. The deployment of this new methodological approach directly on the field can provide valuable chemical and mineralogical analyses.

Risk factors for osteoporosis among postmenopausal women in a Nigerian teaching hospital.

Osteoporosis is a progressive bone disease characterized by a reduction in bone mass and density, leading to bone fragility and an increased risk of sustaining fractures. Several studies have shown that the risk for osteoporosis increases with age and after menopause. A cross-sectional study was undertaken of 422 postmenopausal women at the Family Medicine Clinic of the Lagos State University Teaching Hospital (LASUTH). Variables such as socio-demographic characteristics, anthropometric indices, and lifestyle habits of participants were assessed. In addition, bone mineral density was measured using a validated portable dual-energy X-ray absorptiometry scanner. The results of the bone mineral density were analyzed based on T-scores. The mean age of the study subjects was 59.8± ±6.4 years, while the mean age at menopause was 50.15 ± 4.1 years. The majority of the subjects were obese (41.5%), while the prevalence of osteoporosis and osteopenia was 15.1% and 30.6%, respectively. The use of oral steroids was associated with osteoporosis (P < 0.05). We recommend regular bone mineral density screening of postmenopausal women at the primary care level for early diagnosis and treatment of osteoporosis to prevent fragility fractures.

Acute Myocarditis Mimicking ST-Elevation Myocardial Infarction in 19 Years Old Male with Pneumonia

Background: Acute myocarditis is an inflammatory disease of the heart muscle that manifests clinically with a spectrum of symptoms, ranging from mild chest pain to myocardial infarction. It can also be linked to viral or bacterial illnesses like pneumonia. Case summary: A 19-year-old male with no notable medical history reported to the Emergency Department with substernal chest pain radiating to the left arm, accompanied by nausea and profuse perspiration. His vital signs were stable and his physical examination was normal, with the exception of left lower chest crackles. The electrocardiogram revealed ST segment increase in inferior and lateral leads, along with ST depression in leads V1 through V3. A portable chest x-ray revealed a patchy opacity in the lower lobe of the left lung. Invasive coronary angiography revealed normal coronary arteries. Further evaluation with echocardiography and cardiac MRI revealed characteristics of acute myocarditis, including a minimally dilated LV and subtle hypokinesia in the midventricular inferior and lateral segments, as well as mild global hypokinesia in the LV and RV. Perimyocarditis was detected in the patient, and antiplatelet medication were terminated. Due to a low ejection fraction, Bisoprolol, Ramipril, and spironolactone were administered, and he was hospitalised until his intravenous treatments for pneumonia were completed. Further laboratory tests revealed a decrease in troponin T, white blood cell count, and C-reactive protein. He was discharged with medications including spironolactone, metoprolol, Ramipril, and colchicine. Unfortunately, he failed to comply with the directive. On the eighth day of hospitalisation, a discharge ECG revealed sinus rhythm with no ST-T alterations. Conclusion: When evaluating an acute cardiac event, healthcare practitioners should examine the possibility of uncommon bacterial myocarditis and keep in mind that Streptococcus pneumoniae infection might imitate acute MI in otherwise healthy young males. The timely diagnosis and administration of appropriate antibiotics are critical in the treatment of such conditions.

New chemical and mineralogical data on mosaics from the South aisle wall of Monreale Cathedral (Italy)

Due to the surprising lack of knowledge concerning raw materials and production technology employed to make mosaics after the twelfth century, an archaeometric investigation was carried out on the materials constituting the mosaic decoration of the South aisle wall of Monreale Cathedral (Italy), taking advantage of a conservation intervention. In this work, fallen coloured or gilded glass tesserae to be repositioned were studied by means of a combination of a molecular technique (Raman spectroscopy) and an elemental one (portable X-ray Fluorescence, pXRF); also, efflorescences affecting the general conservation state and samples of the respective bedding mortar were analysed with the former technique and with X-ray diffraction (XRD). The raw materials used and, consequently, the different compositions characterizing gilded vs. coloured glass tesserae were highlighted with the vibrational spectroscopy; chromophores and trace elements were detected by pXRF. This complementary approach allowed to disclose clues about glass-manufacturing technique and raw materials. The nature of the salts was also ascertained through Raman spectroscopy and XRD, for the benefit of the conservation procedure, and connected to the mortars’ composition.

Assessment of the Occupational Radiation Dose from a Handheld Portable X-ray Unit During Full-mouth Intraoral Dental Radiographs in the Dog and the Cat - A Pilot Study.

Occupational radiation protection is an important consideration in small animal clinics world-wide. With the increased use of portable handheld X-ray devices in veterinary dentistry, concerns related to occupational radiation protection are being raised. Annual occupational dose limits for dental workers are expressed as Total Dose Equivalent (TDE) or Effective Dose. The permitted TDE can vary depending on the anatomical region, ranging from 50 millisieverts (mSv) for the external whole body exposure dose to 500 mSv for external exposure of the skin or an extremity. Although several studies have been performed in human dentistry to establish the amount of backscatter radiation produced using portable handheld X-ray devices, no similar research has been conducted in veterinary dentistry. This study aimed to determine the TDE while acquiring a full mouth intraoral radiograph set in dogs and cats and to estimate the TDE for a handheld X-ray device's operator. For this, the backscatter radiation dose recorded by three sets of monitoring dosimeters located in strategic anatomical areas of the operator was assessed after taking one hundred intraoral radiographs in each group. The study concluded that the backscatter radiation levels were far below the permitted annual occupational doses in the three patient groups of this study. Even though the portable handheld X-ray unit was demonstrated to be a safe dental radiographic unit regarding backscattering radiation, the operator's eye, ovary, and breast regions were exposed to unnecessary radiation.

Towards rapid analysis with XRF sensor for assessing soil fertility attributes: Effects of dwell time reduction

The analysis time used for the diagnosis of soil fertility attributes using portable X-ray fluorescence spectroscopy (XRF) sensors (between 30 and 90 s) is too long for in situ applications. The present study aimed at evaluating the trade-off between dwell time and XRF performance for assessing soil fertility attributes. A total of 102 soil samples acquired in two Brazilian agricultural fields were used, whose spectra were obtained using dwell times of 90, 60, 30, 15, 10, 7, 4, and 2 s to build and validate calibration models for clay, cation exchange capacity, and extractable K and Ca. Results revealed that it is possible to make drastic reductions in the XRF dwell time (from 90 to 2 s), while keeping excellent prediction performance [ratio of performance to interquartile distance (RPIQ) between 3.52 and 8.32] for all the studied attributes. A dwell time of only 2 s performed satisfactorily and is an analysis time suitable for rapid in situ applications. In addition, it was shown that data from spectral databases previously collected that used long dwell times (e.g., 30, 60, 90 s) can be extrapolated to fast applications with shorter dwell times (e.g., 2 and 4 s), once standardization by the detector's live time has been performed. Anyhow, calibrations using a dwell time similar to the one of the validation set tended to show superior results and are therefore recommended. This study addresses the need and provides guidelines for optimizing XRF sensor analysis time for in situ applications in the context of precision agriculture.