Exploring the influencing factors of scrub typhus in Gannan region, China, based on spatial regression modelling and geographical detector.

Scrub typhus is a significant public health issue with a wide distribution and is influenced by various determinants. However, in order to effectively eradicate scrub typhus, it is crucial to identify the specific factors that contribute to its incidence at a detailed level. Therefore, the objective of our study is to identify these influencing factors, examine the spatial variations in incidence, and analyze the interplay of two factors on scrub typhus incidence, so as to provide valuable experience for the prevention and treatment of scrub typhus in Gannan and to alleviate the economic burden of the local population.This study employed spatial autocorrelation analyses to examine the dependent variable and ordinary least squares model residuals. Additionally, spatial regression modelling and geographical detector were used to analyze the factors influencing the annual mean 14-year incidence of scrub typhus in the streets/townships of Gannan region from 2008 to 2021. The results of spatial1 autocorrelation analyses indicated the presence of spatial correlation. Among the global spatial regression models, the spatial lag model was found to be the best fitting model (log likelihood ratio = -319.3029, AIC = 666.6059). The results from the SLM analysis indicated that DEM, mean temperature, and mean wind speed were the primary factors influencing the occurrence of scrub typhus. For the local spatial regression models, the multiscale geographically weighted regression was determined to be the best fitting model (adjusted R2 = 0.443, AICc = 726.489). Further analysis using the MGWR model revealed that DEM had a greater impact in Xinfeng and Longnan, while the southern region was found to be more susceptible to scrub typhus due to mean wind speed. The geographical detector results revealed that the incidence of scrub typhus was primarily influenced by annual average normalized difference vegetation index. Additionally, the interaction between GDP and the percentage of grassland area had a significant impact on the incidence of scrub typhus (q = 0.357). This study illustrated the individual and interactive effects of natural environmental factors and socio-economic factors on the incidence of scrub typhus; and elucidated the specific factors affecting the incidence of scrub typhus in various streets/townships. The findings of this study can be used to develop effective interventions for the prevention and control of scrub typhus.

In-silico study of the impact of system design parameters on microcalcification detection in wide-angle digital breast tomosynthesis.

Purpose: Accurate detection of microcalcifications ( µ Calcs ) is crucial for the early detection of breast cancer. Some clinical studies have indicated that digital breast tomosynthesis (DBT) systems with a wide angular range have inferior µ Calc detectability compared with those with a narrow angular range. This study aims to (1) provide guidance for optimizing wide-angle (WA) DBT for improving µ Calcs detectability and (2) prioritize key optimization factors. Approach: An in-silico DBT pipeline was constructed to evaluate µ Calc detectability of a WA DBT system under various imaging conditions: focal spot motion (FSM), angular dose distribution (ADS), detector pixel pitch, and detector electronic noise (EN). Images were simulated using a digital anthropomorphic breast phantom inserted with 120 µ m µ Calc clusters. Evaluation metrics included the signal-to-noise ratio (SNR) of the filtered channel observer and the area under the receiver operator curve (AUC) of multiple-reader multiple-case analysis. Results: Results showed that FSM degraded µ Calcs sharpness and decreased the SNR and AUC by 5.2% and 1.8%, respectively. Non-uniform ADS increased the SNR by 62.8% and the AUC by 10.2% for filtered backprojection reconstruction with a typical clinical filter setting. When EN decreased from 2000 to 200 electrons, the SNR and AUC increased by 21.6% and 5.0%, respectively. Decreasing the detector pixel pitch from 85 to 50 µ m improved the SNR and AUC by 55.6% and 7.5%, respectively. The combined improvement of a 50 µ m pixel pitch and EN200 was 89.2% in the SNR and 12.8% in the AUC. Conclusions: Based on the magnitude of impact, the priority for enhancing µ Calc detectability in WA DBT is as follows: (1) utilizing detectors with a small pixel pitch and low EN level, (2) allocating a higher dose to central projections, and (3) reducing FSM. The results from this study can potentially provide guidance for DBT system optimization in the future.

Development of a cost-effective confocal Raman microscopy with high sensitivity.

Confocal Raman microscopy is a powerful technique for identifying materials and molecular species; however, the signal from Raman scattering is extremely weak. Typically, handheld Raman instruments are cost-effective but less sensitive, while high-end scientific-grade Raman instruments are highly sensitive but extremely expensive. This limits the widespread use of Raman technique in our daily life. To bridge this gap, we explored and developed a cost-effective yet highly sensitive confocal Raman microscopy system. The key components of the system include an excitation laser based on readily available laser diode, a lens-grating-lens type spectrometer with high throughput and image quality, and a sensitive detector based on a linear charge-coupled device (CCD) that can be cooled down to -30 °C. The developed compact Raman instrument can provide high-quality Raman spectra with good spectral resolution. The 3rd order 1450 cm-1 peak of Si (111) wafer shows a signal-to-noise ratio (SNR) better than 10:1, demonstrating high sensitivity comparable to high-end scientific-grade Raman instruments. We also tested a wide range of different samples (organic molecules, minerals and polymers) to demonstrate its universal application capability.

Development of a hydrophilic-lipophilic-balanced copolymer@zirconium-based metal-organic framework-based solid-phase microextraction probe for the trace determination of organophosphorus pesticides in tea infusions.

Organophosphorus pesticides (OPPs) present in tea infusions pose a serious threat to human health. In this study, a sensitive method for the determination of OPPs was developed based on a direct-immersion solid-phase microextraction (DI-SPME) probe. By fine adjustment of the ratio and one-step polymerization of dihydroxy-functionalized zirconium-based metal-organic framework UiO-66-(OH)2 and divinylbenzene-N-vinyl pyrrolidone (DVB-NVP) microspheres, the DVB-NVP@ UiO-66-(OH)2 (D-N@U) composite with an optimal hydrophilic-lipophilic balance (HLB) was achieved. Furthermore, D-N@U was adhesively bonded to stainless-steel wires to fabricate a DI-SPME probe. OPPs, especially those with nonpolar properties characterized by a high octanol-water partition coefficient (log KOW), were selectively and efficiently enriched on the D-N@U-coated DI-SPME probe from tea infusions. Coupled with a gas chromatography-flame photometric detector, the as-fabricated D-N@U-coated DI-SPME probe achieved good performance for OPPs analysis with a wide linear dynamic range of 0.10-500.00 µg/L and low detection limits of 1.96-6.69 ng/L. Moreover, in spiked samples, the recoveries and relative standard deviations were in the ranges of 73.12%-101.20 % and 1.03%-6.56 %, respectively. Owing to its simple operation, high extraction efficiency, and high sensitivity, this approach has great potential for the rapid determination of multiple pesticide trace-level residues in food.

Ecological, environmental risks and sources of arsenic and other elements in soils of Tuotuo River region, Qinghai-Tibet Plateau.

Against the backdrop of global warming, the pollutants that were once "temporarily stored" in the permafrost are gradually being released, posing significant impacts on the environment. This has become an internationally focused hot topic. In this study, the contents of 11 elements such as As, Ti, Cd, Cr, Co, Mn, Cu, Pb, Ni, Zn and V in soil samples from 128 sampling points in the freeze-thaw area of the Tuotuo River in the source region of the Yangtze River on the Qinghai-Tibet Plateau were determined to evaluate the possible sources, contamination status and ecological, environmental and health risks of these elements. The mean values of As, Cd, Pb and Zn were higher than the corresponding Tibet soil background values. Among fourteen PTEs, As, Cd and Pb had the highest average values of enrichment factor and pollution index, indicating that freeze-thaw area soils showed moderate enrichment and pollution with As, Cd and Pb. Mean ecological risk factor (ER) of Cd was 109 and other PTEs mean ER values < 40, whereas ecological risk index (RI) values of all PTEs ranged from 59.5 to 880 and mean RI values was 152, indicating moderate ecological risk in study area. Explanatory power q value of total S (TS) content was 0.217 by GeogDetector, indicating TS was the most significant contributing factor to RI. Correlation analysis and PCA analysis showed that Cr, Cu, Ni, Co, Mn, Ti, V were mainly originated from natural sources, Cd, Pb and Zn from traffic activity, As from long-distance migration-freeze-thaw.

Energy-integrating detector based ultra-high-resolution CT with deep learning reconstruction for the assessment of calcified lesions in coronary artery disease.

BACKGROUND: The aim of this study to compare of the image quality of calcified lesions in coronary artery disease between deep learning reconstruction (DLR) and model-based iterative reconstruction (MBIR) on energy-integrating detector (EID) based ultra-high-resolution CT (UHRCT). METHODS: We performed a phantom study on EID-based UHRCT using a dedicated insert for calcifications and obtained the derivative values for DLR and MBIR. In the clinical study, the derivative values were compared between DLR and MBIR across 73 calcified lesions in 62 patients. Edge sharpness of calcifications and contrast resolution at the coronary lumen side were quantified by the maximum and minimum derivative values. Two radiologists independently analyzed image quality of the calcified lesions using a 5-point Likert scale. RESULTS: In the phantom study, the edge sharpness of the 3-mm calcifications on DLR (median, 924 HU/mm; IQR, 580-1741 HU/mm) was significantly higher than on MBIR (median, 835 HU/mm; IQR, 484-1552; p â€‹< â€‹0.001). In the clinical study, the image quality of the calcified lesions was significantly better on DLR with significantly reduced reconstruction time (p â€‹< â€‹0.001). The contrast resolution at the coronary lumen side on DLR (median, -99.1 HU/mm; IQR, -209 to -34.3 HU/mm) was significantly higher than on MBIR (median, -41.8 HU/mm; IQR, -121 to 22.3 HU/mm, p â€‹< â€‹0.001) although the edge sharpness of calcifications was similar between DLR and MBIR (p â€‹= â€‹0.794) in the clinical setting. CONCLUSION: EID-based UHRCT reconstructed using DLR represents better image quality of calcified lesions in coronary artery disease compared with MBIR, with significantly reduced reconstruction time.

Estimation of radiological health risks due to 226Ra, 232Th, and 40K in foods consumed in Iraqi Kurdistan Region.

This study investigates the activity concentration of natural radionuclides in a diverse range of food samples in the Koya district markets food baskets, including both domestic and imported products. The samples cover annual crops (e.g. coffee, tea, kidney beans), tree nuts (e.g. almonds, pistachios), and other items (e.g. beef, fish, milk) by using a high-purity germanium (HPGe) detector. This research addresses a notable gap by providing baseline data on radionuclide concentrations and assessing potential health risks. Average activity concentrations for ²²6Ra, ²³²Th, and 4°K were 0.943, 0.367, and 191.8 Bq kg-1, respectively. Radium equivalent activity values ranged from 2.88-58.48 Bq kg-1, all below the safety limit. The average excess lifetime cancer risk (ELCR) was 0.154 mSv a-1, indicating safety for most samples, though coffee and tea showed higher levels. This study provides new data crucial for future research and regulatory monitoring, underscoring the need for further investigation into geological impacts on radionuclide levels.

Performance of iodine quantification through high-pitch dual-source photon-counting CT: a phantom study.

PURPOSE: To investigate the feasibility and accuracy of iodine quantification using PCD-CT in standard-pitch and high-pitch scanning at different scan parameters in a phantom model. MATERIALS AND METHODS: Four inserts with known iodine concentrations (2, 5, 10, and 15 mg/mL) were placed in the removable CT phantom and scanned using high-pitch (3.2) and standard-pitch (0.8) modes on PCD-CT. Two tube voltages (120 and 140 kVp) and four radiation doses (1, 3, 5, and 10 mGy) were alternated. Each scan setting was repeated three times. Mean iodine concentration for each insert across three consecutive slices was recorded. Percentage absolute bias (PAB) was assessed for iodine quantification. RESULTS: A total of 96 acquisitions were conducted. In small phantom, the average for PAB was 2.96% (range: 1.75% ~ 4.56%) and 1.67% (range: 1.00% ~ 3.42%) for high-pitch and standard-pitch acquisitions, respectively. In large phantom, it was 3.72% (range: 1.75% ~ 5.97%) and 2.94% (range: 1.75% ~ 4.70%). Linear regression analysis revealed that only phantom size significantly influenced (P < 0.001) the accuracy of iodine quantification. CONCLUSION: The high-pitch scan mode in PCD-CT can be used to quantify iodine density with similar accuracy compared with standard pitch.

Coronary stent imaging in photon counting computed tomography: improved imaging of in-stent stenoses in a phantom with optimized reconstruction kernels.

Objectives: Coronary CT angiography (CCTA) is becoming increasingly important in the workup of coronary artery disease. Imaging of stents and in-stent stenoses remains a challenge. This work investigates the assessability of in-stent stenoses in photon counting CT (PCCT) using ultra-high-resolution (UHR) imaging and optimized reconstruction kernels. Methods: In an established phantom, 6 stents with inserted hypodense stenoses were scanned in both standard resolution (SRM) and UHR in a clinical PCCT scanner (NAEOTOM Alpha, Siemens Healthineers, Germany). Reconstructions were made both with the clinically established and optimized kernels. The visible stent lumen and the extent of stenosis were quantitatively measured and compared with the angiographic reference standard. Also, region-of-interest (ROI)-based measurements and a qualitative assessment of image quality were performed. Results: The visible stent lumen and the extent of stenosis were measured more precisely in UHR compared to SRM (0.11 ± 0.19 vs 0.41 ± 0.22 mm, P < .001). The optimized kernel further improved the accuracy of the measurements and image quality in UHR (0.35 ± 0.23 vs 0.47 ± 0.19 mm, P < .001). Compared to angiography, stenoses were overestimated in PCCT, on average with an absolute difference of 18.20% ± 4.11%. Conclusions: Photon counting CCTA allows improved imaging of in-stent stenoses in a phantom using UHR imaging and optimized kernels. These results support the use of UHR and optimized kernels in clinical practice and further studies. Advances in knowledge: UHR imaging and optimized reconstruction kernels should be used in CCTA in the presence of cardiac stents.

Photon-counting computed tomography in radiology.

Photon-counting detector computed tomography (PCD-CT) devices have recently been introduced into practice, despite photon-counting detector technology having been studied for many years. PCD-CT devices are expected to provide advantages in dose reduction, tissue specificity, artifact-free imaging, and multi-contrast demonstration capacity. Noise reduction and increased spatial resolution are expected using PCD-CT, even under challenging scanning conditions. Some experimental or preliminary studies support this hypothesis. This pictorial review illustrates the features of PCD-CT systems, particularly in the interventional field. PCD-CT offers superior image quality and better lesion discrimination than conventional CT techniques for various conditions. PCD-CT shows significant improvements in many aspects of vascular imaging. It is still in its early stages, and several challenges have been identified. Also, PCD-CT devices have some important caveats. The average cost of these devices is 3 to 4 times higher than conventional CT units. This additional cost must be justified by improved clinical benefits or reduced clinical harms. Further investigations will be needed to resolve these issues.

Optimal weighting strategies for maximizing contrast-to-noise ratio in photon counting CT images.

BACKGROUND: Photon counting detectors (PCDs) with energy discrimination capabilities have the potential to generate grayscale CT images with improved contrast-to-noise ratio (CNR) through optimal weighting of their spectral measurements. PURPOSE: This study evaluates the CNR performance of grayscale CT projections and images generated from spectral measurements of PCDs using three energy-weighting strategies: pre-log weighting, post-log weighting, and material decomposition (MD) weighting. This study provides the expressions of optimal weights and maximum achievable CNR of these energy-weighting strategies, which only require the knowledge of detected bin counts and do not require information of PCD energy responses or imaging techniques. METHODS: We defined and solved a generalized eigenvalue problem to obtain the maximum achievable CNR in the projection domain for low-contrast tasks using three energy-weighting strategies: pre-log weighting (weighted sum of energy bin counts), post-log weighting (weighted sum of line integrals), and MD weighting (weighted sum of basis material thicknesses, which is equivalent to virtual monoenergetic images [VMIs]). These expressions only contain energy bin counts from PCD measurements. We used a realistic PCD energy response model to simulate the detected bin counts and conducted Monte Carlo simulations of different contrast tasks and phantoms to evaluate the projection- and image-domain CNR performance of these energy-weighting strategies. Additionally, the total counts method (a special case of pre-log weighting with unity weights) was included for comparison. We also conducted Gammex head and body phantom scans on an edge-on-irradiated silicon PCCT prototype to evaluate the image-domain CNR performance of these energy-weighting strategies. RESULTS: The results show that pre-log, post-log, and MD weighting strategies generate approximately equal projection-domain maximum achievable CNR, with a difference of less than 2%, and outperform the total counts method. These three energy-weighting strategies also generate approximately equal image-domain maximum CNR when the contrast task is located at the center of a homogeneous phantom. Pre-log weighting generates the highest image-domain CNR for an off-center contrast task location or inhomogeneous phantoms while also outperforming the total counts method. CONCLUSIONS: We derived the expression of projection-domain maximum achievable CNR using three energy-weighting strategies. Our results suggest that using pre-log weighting strategies enables fast grayscale CT image generation with high CNR from spectral PCD measurements for inhomogeneous phantoms and off-center region of interests (ROIs).

High-sensitivity and spatial resolution benchtop cone beam XFCT imaging system with pixelated photon counting detectors using enhanced multipixel events correction method.

OBJECTIVE: High atomic number element nanoparticles have shown potential in tumor diagnosis and therapy. X-ray fluorescence computed tomography (XFCT) technology enables quantitative imaging of high atomic number elements by specifically detecting characteristic X-ray signals. The potential for further biomedical applications of XFCT depends on balancing sensitivity, spatial resolution, and imaging speed in existing XFCT imaging systems. APPROACH: In this study, we utilized a high-energy resolution pixelated photon-counting detector for XFCT imaging. We tackled degradation caused by multi-pixel events in the photon-counting detector through energy and interaction position corrections. Sensitivity and spatial resolution imaging experiments were conducted using PMMA phantoms to validate the effectiveness of the multi-pixel events correction algorithm. MAIN RESULTS: After correction, the system's sensitivity and spatial resolution have both improved. Furthermore, XFCT/CBCT dual-modality imaging of gadolinium nanoparticles within mice subcutaneous tumor was successfully achieved. SIGNIFICANCE: These results demonstrate the preclinical research application potential of the XFCT/CBCT dual-modality imaging system in high atomic number nanoparticle-based tumor diagnosis and therapy.

Objective detection of wheeze at home by parents through a digital device: usage patterns and relationship with SABA administration.

INTRODUCTION: Wheezing is an important indicator of exacerbated respiratory symptoms in early childhood and must be monitored to regulate pharmacological therapy. However, parents' subjective perception of wheezing in their children is not always precise. We investigated the objective identification of children's wheezing by parents using a digital wheeze detector (WheezeScanTM, OMRON Healthcare Co. Ltd), its longitudinal usage patterns, and its relationship with SABA administration. METHODS: We conducted a secondary nested analysis of data from the intervention arm of a multi-center randomized controlled trial completed in 2021-2022 in Berlin (Germany), London (United Kingdom), and Istanbul (Turkey). Children aged 4 to 84 months with doctor's diagnosed wheezing (GINA step 1 or 2) were included. Using an electronic diary (Wheeze-MonitorTM, TPS), parents monitored and recorded for 120 days at home the presence or absence of their child's wheezing, detected both, with WheezeScanTM ("objective" wheezing), and subjective ("perceived" wheezing). Parents also recorded the child's symptoms, medication intake, and family quality of life. Questionnaires regarding symptom control, quality of life, and parental self-efficacy were answered at baseline and after 90 and 120 days. RESULTS: Eighty-one/87 families completed the intervention arm of the study. WheezeScanTM was on average used 0.7 (SD 0.6) times a day, with each patient reporting a positive, negative, or "error" outcome on average in 57%, 39%, and 5% of measurements, respectively. The use of WheezeScanTM declined slightly during the first 90 days of monitoring and steeply thereafter. Repeated usage of WheezeScanTM in the same day was more frequent after a "wheeze" (HR 1.5, 95% CI 1.37-1.65, p < 0.001) and an "error" (HR 2.01, 95% CI 1.70-2.38, p < 0.001) result, compared to a "no wheeze" outcome. The average per-patient daily agreement between "objective" and "perceived" wheezing/non-wheezing was 75% at the start of the monitoring period and only weakly persisted as time passed (Spearman's rho=0.09). The frequency of short-acting beta-2-agonists (SABA) administration was lower in days with closely interspaced consecutive device uses during which the patient's status was perceived as "never wheeze" (32/455, 7%) than in those perceived as "persistent wheeze" (53/119, 44%; OR 36.6, 95% CI [14.3, 94.1]). CONCLUSION: Daily use of a digital WheezeScanTM at home allows parents to detect their child's unperceived wheezing and discloses to caregivers the longitudinal patterns of a child's wheezing disorder. Digital monitoring of wheezing also highlights poor adherence to guidelines in SABA administration for wheezing children, with under-treatment being much more frequent than over-treatment. This pioneering study opens new perspectives for further investigation of digital wheeze detectors in the early diagnosis and proper self-management of wheezing disorders in childhood.

Association of liver multi-parameter quantitative metrics determined by dual-layer spectral detector computed tomography (SDCT) with coronary plaque scores.

Background: Hepatic steatosis is closely related to the occurrence and development of coronary plaques. Spectral detector computed tomography (SDCT) can provide more precise multiparameter quantitative parameters for hepatic steatosis. Hence, the purpose of this cross-sectional study was to explore the effect of quantitative liver metrics measured using SDCT on the extent and severity of coronary plaques. Methods: In patients who underwent upper abdomen unenhanced SDCT and coronary computed tomography angiography, plaque extent and severity were assessed using segmental involvement score (SIS) and segmental stenosis score (SSS). Liver fat quantification was evaluated by polychromatic and virtual mono-energetic images at 40 and 70 kev, spectral attenuation curve slope, and effective atomic number (CT40 keV, CT70 kev, λHU, and Zeff, respectively). A logistic regression model evaluated the factors influencing high SIS and SSS. Results: Enrolled patients (n=644) were divided into groups: low SIS (<5) (n=451), high SIS (≥5) (n=193), low SSS (<5) (n=461), and high SSS (≥5) (n=183). Zeff was more closely correlated with SIS (standard partial regression coefficient =-0.422, P<0.001) and SSS (standard partial regression coefficient =-0.346, P<0.001). Zeff was divided into four groups using interquartile intervals. Compared with the patients in the lowest quartile, those in the second [odds ratio (OR) =2.116, 95% confidence interval (CI): 1.134-3.949, P=0.018], third (OR =2.832, 95% CI: 1.461-5.491, P=0.002), and fourth (OR =3.584, 95% CI: 1.857-6.918, P<0.001) quartiles showed higher risk for high SIS. And correspondingly, the second (OR =1.933, 95% CI: 1.040-3.592, P=0.037), third (OR =2.900, 95% CI: 1.499-5.609, P=0.002), and fourth (OR =3.368, 95% CI: 1.743-6.510, P<0.001) quartiles showed higher risk for high SSS, especially in those who were <60 years old, male and had visceral adipose tissue/subcutaneous adipose tissue <1.18. Conclusions: The SDCT-Zeff was an independent factor associated with high SIS and SSS. The quantification of liver fat may be useful for evaluating the risk and prognosis of coronary atherosclerosis.

Monoenergetic reconstructions and iodine density maps for visualization of coronary artery stents using 8-cm dual-layer detector spectral computed tomography: an in vitro phantom study.

Background: The effectiveness of coronary computed tomography (CT) angiography in assessing stent restenosis is hindered by heavy metal artifacts. This study aimed to evaluate the image quality of monoenergetic reconstructions and iodine density map for coronary stent imaging using an 8-cm dual-layer detector spectral CT. Methods: In this study, 8 stents with a diameter <3 mm (group A) and 10 with a diameter ≥3 mm (group B) were placed in plastic tubes filled with iodinated contrast media and scanned. The internal diameter of the prepared stents was then measured by intravascular ultrasound. The reconstructed images included iodine density maps, conventional images, and different energy levels. The visualization of the stent lumen and stent structure was subjectively assessed using a 4-point Likert scale. The objective evaluation was performed using the in-stent lumen signal-to-noise ratio (SNRis), non-stent lumen SNR (SNRns), internal diameter difference (IDD), and blooming artifact index (BAI). The Friedman test and analysis of variance were used for multiple comparisons. Results: For lumen visualization, the optimal monoenergetic images received the highest score for both group A (2.56±0.51) and group B (3.1±0.55). Multiple comparisons showed that there were significant differences between the optimal monoenergetic images and iodine density maps. However, for stent structure, iodine density maps received the highest score for group A (3.0±0.52) and group B (3.8±0.41). For quantitative assessment, the optimal monoenergetic images had the highest SNRis and SNRns, while the iodine density maps had the lowest SNRis and SNRns. For IDD and BAI, the iodine density maps yielded the smallest value. Conclusions: The monoenergetic images on the second-generation dual-layer detector CT provide better visualization of the lumen and higher SNR. However, iodine density maps are superior for evaluating stent structure and IDD and BAI compared to monoenergetic and conventional reconstructions.

Coronary CT angiography-based FFR with ultrahigh-resolution photon-counting detector CT: Intra-individual comparison to energy-integrating detector CT.

PURPOSE: To evaluate the feasibility of CT angiography-derived fractional flow reserve (CT-FFR) calculations on ultrahigh-resolution (UHR) photon-counting detector (PCD)-CT series and to intra-individually compare the results with energy-integrating (EID)-CT measurements. METHOD: Prospective patients with calcified plaques detected on EID-CT between April 1st, 2023 and January 31st, 2024 were recruited for a UHR CCTA on PCD-CT within 30 days. PCD-CT was performed using the same or a lower CT dose index and an equivalent volume of contrast media. An on-site machine learning algorithm was used to obtain CT-FFR values on a per-vessel and per-patient basis. For all analyses, CT-FFR values ≤ 0.80 were deemed to be hemodynamically significant. RESULTS: A total of 34 patients (age: 67.3 ± 6.6 years, 7 women [20.6 %]) were included. Excellent inter-scanner agreement was noted for CT-FFR values in the per-vessel (ICC: 0.93 [0.90-0.95]) and per-patient (ICC: 0.94 [0.88-0.97]) analysis. PCD-CT-derived CT-FFR values proved to be higher compared to EID-CT values on both vessel (0.58 ± 0.23 vs. 0.55 ± 0.23, p < 0.001) and patient levels (0.73 ± 0.23 vs. 0.70 ± 0.22, p < 0.001). Two patients (5.9 %) with hemodynamically significant lesions on EID-CT were reclassified as non-significant on PCD-CT. All remaining participants were classified into the same category with both scanner systems. CONCLUSIONS: While UHR CT-FFR values demonstrate excellent agreement with EID-CT measurements, PCD-CT produces higher CT-FFR values that could contribute to a reclassification of hemodynamic significance.

[Ecological Environment Quality Monitoring of Qitai Oasis Based on Land Use/Cover Change and Remote Sensing Ecological Index].

Based on Landsat remote sensing images, this study conducted a quantitative assessment of the spatiotemporal alterations in the ecological environment quality at the Qitai Oasis in Xinjiang, situated at the northern foothills of the Tianshan Mountains, triggered by human activities. This assessment was conducted through a combination of the remote sensing ecological index （RSEI） and land use/cover change （LUCC）. In addition, we used spatial autocorrelation analysis and geographic detector to examine the spatial distribution characteristics and its influencing factors of RSEI. The results demonstrated that： ① The average RSEI values for Qitai Oasis in four different years （2001, 2007, 2014, and 2022） were 0.392, 0.423, 0.452, and 0.438, respectively, indicating a lower overall level of ecological environment quality in the area. The spatial distribution highlighted a poor level in the northern and southern regions, with the central area displaying noticeably better quality. The temporal trend showed an initial growth followed by a subsequent decline, with an overall tendency toward an increase. ② The ecological environment quality in the Qitai Oasis exhibited positive spatial autocorrelation, with low-low clustering primarily concentrated in the northern part of the oasis, closer to the Gurbantünggüt Desert. Further, the high-high clustering was featured by an aggregation from scattered distribution towards the central agricultural areas of the oasis. ③ Natural factors had a negligible influence on the spatial distribution of RSEI in Qitai Oasis, and the primary catalyst for RSEI changes was LUCC. ④ RSEI aptly portrayed the present condition of the ecological environment quality in the Qitai Oasis. Changes in RSEI of natural ecosystems, such as RSEI of grassland and bare land, provided significant cues, illustrating the variations in the ecological environment quality of arid regions.

Optimization of the Cold Water Extraction Method for High-Value Bioactive Compounds from Chamomile (Matricaria chamomilla L.) Flower Heads Through Chemometrics.

This study focused on optimizing a cold water extraction method to obtain bioactive compounds from chamomile (Matricaria chamomilla L.), addressing increasing consumer demand for natural products and nutraceuticals. A full-factorial design was employed to evaluate the effects of temperature, time, and chamomile amount on the polyphenolic profile of extracts. The samples were characterized by HPLC-DAD and UV-Vis coupled with chemometrics; the analysis showed that extraction time negatively affected extract quality, as did the interaction between time and temperature. In addition, a significant positive quadratic effect for temperature and a positive coefficient for chamomile amount was found. ASCA was used to assess the UV-Vis profile, offering an alternative untargeted method for understanding the variable effects. The optimal extraction conditions (25 °C, 32 min, and 2.5 g of chamomile) produced samples high in hydroxybenzoic and hydroxycinnamic acids and flavanol derivatives. Using A face-centered design, this study also monitored antioxidant activity via a DPPH scavenging assay, confirming that the optimal conditions yielded samples within the range of maximum antioxidant activity in the studied experimental domain.

Research on the NI-MLA Method for Enhancing the Spot Position Detection Accuracy of Quadrant Detectors Under Atmospheric Turbulence.

The distorted spots induced by atmospheric turbulence significantly degrade the spot position detection accuracy of the quadrant detector (QD). In this paper, we utilize angular measurement and homogenization characteristics of non-imaging microlens array (NI-MLA) systems, effectively reducing the distortion degree of the spots received on the QD target surface, thereby significantly enhancing the spot detection accuracy of the QD. First, based on the principles of geometric optics and Fourier optics, it is proved that the NI-MLA system possesses the angular measurement characteristic (AMC) within the paraxial region while deriving and verifying the focal length of the system. Then, the QD computation curve characteristics of the system under non-turbulence are explored. This study further elucidates the mathematical principle of the NI-MLA system for mitigating the spot position detection random error of QD (SPDRE-QD) and discusses in depth the relationship between the NI-MLA system's capability to mitigate the SPDRE-QD and the system's parameters under various turbulence intensities. Finally, it is experimentally verified that the root-mean-square error (RMSE) of the QD computation values using the NI-MLA system are reduced by a significant improvement of at least 2.44 times and up to 17.36 times compared with that of the conventional optical system of QD (COS-QD) under turbulence conditions ranging from weak to strong.

Study on the impact of bowtie filter on photon-counting CT imaging.

Objective.The aim of this study was to investigate the impact of the bowtie filter on the image quality of the photon-counting detector (PCD) based CT imaging.Approach.Numerical simulations were conducted to investigate the impact of bowtie filters on image uniformity using two water phantoms, with tube potentials ranging from 60 to 140 kVp with a step of 5 kVp. Subsequently, benchtop PCD-CT imaging experiments were performed to verify the observations from the numerical simulations. Additionally, various correction methods were validated through these experiments.Main results.It was found that the use of a bowtie filter significantly alters the uniformity of PCD-CT images, depending on the size of the object and the x-ray spectrum. Two notable effects were observed: the capping effect and the flattening effect. Furthermore, it was demonstrated that the conventional beam hardening correction method could effectively mitigate such non-uniformity in PCD-CT images, provided that dedicated calibration parameters were used.Significance.It was demonstrated that the incorporation of a bowtie filter results in varied image artifacts in PCD-CT imaging under different conditions. Certain image correction methods can effectively mitigate and reduce these artifacts, thereby enhancing the overall quality of PCD-CT images.