INTRODUCTION: Photon-counting detector (PCD) CT represents a major advancement in CT imaging, offering improved image quality and reduced radiation dose compared to traditional energy-integrating detector (EID) CT. This study compared image quality and radiation dose using a self-controlled approach, while evaluating the impact of patient positioning. METHODS: This retrospective study analyzed data from 200 patients who underwent abdominal CT scans on both EID (Somatom Definition Flash) and PCD (Naeotom Alpha) scanners. After applying inclusion criteria for proper positioning (within ±20 mm) and stable anatomical conditions, 119 patients were included. Radiation doses were assessed using CTDIvol, and image quality was evaluated via CT numbers, noise levels, signal-to-noise ratio (SNR), SNR to dose (SNRD), and contrast-to-noise ratio to dose (CNRD). RESULTS: The study found a median radiation dose reduction of 37 % with PCD CT compared to EID CT (p < 0.05). Image quality assessments revealed significant improvements with PCD CT, including reduced noise levels (up to 31 % in contrast-enhanced organs) and enhanced SNRD (33-51 % increase). CNRD improved by 60-76 %, indicating superior imaging performance of PCD CT. However, 36 % of patients on EID were positioned outside the ±20 mm range, which could adversely affect image quality and radiation dose, underscoring the need for more precise patient positioning. CONCLUSION: This study confirms that PCD CT achieves substantial reductions in radiation dose while enhancing image quality. However, accurate patient positioning is crucial to fully optimize these benefits. Automated tools that ensure proper positioning may be necessary to consistently maintain image quality and reduce radiation exposure. IMPLICATIONS FOR PRACTICE: PCD CT offers improved patient safety and diagnostic imaging. Automated positioning tools are essential to optimize and consistently maintain image quality and minimize radiation exposure.
- MeSH
- Radiation Dosage * MeSH
- Adult MeSH
- Photons MeSH
- Middle Aged MeSH
- Humans MeSH
- Tomography, X-Ray Computed * methods MeSH
- Patient Positioning * methods MeSH
- Signal-To-Noise Ratio MeSH
- Radiography, Abdominal * methods MeSH
- Retrospective Studies MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
Kontext: Dosud se toho ví málo o možné spojitosti mezi cévním zásobením štítné žlázy a aterosklerotickou zátěží koronárních tepen u pacientů s podezřením na ischemickou chorobu srdeční. Cíle: Posoudit možnou spojitost mezi dopplerovskými parametry horní štítné tepny a markery aterosklerózy koronárních tepen včetně závažnosti stenózy, kalcifikace koronárních tepen (cAc) a rozsahu plátu zjištěného koronarografickým vyšetřením pacientů s podezřením na ischemickou chorobu srdeční (ichS) metodou multidetektorové výpočetní tomografie (MDct). Pacienti a metody: Do této průřezové studie bylo zařazeno 100 pacientů s bolestí na hrudi, u nichž byla pro vyloučení okluzivní ischemické choroby srdeční provedena koronarografie MDct. Všichni zařazení pacienti byli z klinického hlediska eutyreoidní, bez klinických známek hypotyreózy nebo hypertyreózy. u zařazených pacientů byla pro stanovení cévních parametrů včetně indexu rezistence (ri), maximální rychlosti proudění krve v systole (PSV), rychlosti proudění krve na konci diastoly (eDV) a indexu pulsatility (pulsatility index, Pi) sonograficky vyšetřena horní štítná tepna. Výsledky: Byla nalezena statisticky významná spojitost mezi sníženými hodnotami PSV (16 cm/s vs. 15 cm/s; p = 0,03) a cAc ≥ 400, a to i po další adjustaci na rizikové faktory koronárních příhod (or [ci] = 0,3 [0,1–0,8]; p = 0,03). Pacienti s významnou koronární stenózou (≥ 50%) vykazovali vyšší hodnoty ri (0,58 vs. 0,54; p = 0,04) než jedinci bez významné koronární stenózy (< 50%). Po adjustaci na jiné rizikové faktory koronárních příhod však již tato spojitost nepřetrvávala. nebyla pozorována spojitost mezi parametry vyšetření štítné žlázy dopplerovským ultrazvukem včetně PSV, eDV, ri a Pi na jedné straně, a přítomností koronárních plátů na straně druhé. Závěr: hodnoty PSV a ri v horní štítné tepně vykazovaly statisticky významnou spojitost se zátěží cAc a s významnou koronární stenózou. tyto výsledky mohou naznačovat možné spojení mezi parametry rezistence cév štítné žlázy a zátěží aterosklerózou koronárních tepen.
Background: Little is known about the potential association between thyroid vascular parameters and coronary atherosclerotic burden in patients with suspected coronary artery disease. Objectives: To assess the potential association between superior thyroid artery Doppler parameters and coronary atherosclerotic markers, including stenosis severity, coronary artery calcification (CAC), and plaque assessed by multi-detector CT (MDCT) coronary angiography among patients with suspected coronary artery disease (CAD). Patients and methods: This cross-sectional study included 100 patients with chest pain who underwent MDCT coronary angiography to exclude the presence of occlusive coronary artery disease. All of the enrolled patients were clinically euthyroid, with no clinical features of hypothyroidism or hyperthyroidism. The superior thyroid artery in enrolled patients was examined using ultrasound to assess vascular parameters, including resistive index (RI), peak systolic velocity (PSV), end-diastolic velocity (EDV), and pulsatility index (PI). Results: There was a significant association between decreased PSV values (16 cm/s vs. 15 cm/s, p = 0.03) and CAC ≥400, even after further adjustment for coronary risk factors (OR (CI) = 0.3 (0.1-0.8. p = 0.03). Patients with significant coronary stenosis severity ≥50% had higher RI values (0.58 vs. 0.54, p = 0.04) than those with a non-significant coronary stenosis <50%. However, this association did not persist after adjustment for other coronary risk factors. No significant association was observed between thyroid Doppler parameters, including PSV, EDV, RI, and PI, and coronary plaque presence. Conclusion: PSV and RI of the superior thyroid artery showed a significant association with CAC burden and significant coronary stenosis. These results may suggest a possible link between thyroid vascular resistance parameters and coronary atherosclerosis burden.
- MeSH
- Atherosclerosis * diagnostic imaging pathology MeSH
- Computed Tomography Angiography MeSH
- Coronary Vessels diagnostic imaging pathology MeSH
- Coronary Stenosis diagnostic imaging pathology MeSH
- Middle Aged MeSH
- Humans MeSH
- Multidetector Computed Tomography MeSH
- Cross-Sectional Studies MeSH
- Heart Disease Risk Factors MeSH
- Statistics as Topic MeSH
- Thyroid Gland * diagnostic imaging blood supply pathology MeSH
- Ultrasonography, Doppler MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Clinical Study MeSH
The cross-section measurement of Antimony (Sb) is pivotal to modify or stagnate the rate of neutron flux in nuclear reactors. Neutron induced reaction cross-section data for isotopes of Sb is meagre as per reported in EXFOR. A comprehensive attempt has been made to analyse the reaction cross-section of 121Sb and 123Sb at monoenergetic neutron energy of 14.96 ± 0.03 MeV. The experiment was performed at the Neutron and Ion Irradiation Facility, Institute for Plasma Research (IPR), Gujarat (India). The 27Al(n,α)24Na reaction is used to monitor the flux and to estimate the cross-section of (n,2n), (n,p) reactions using neutron activation technique. Monoenergetic neutrons generated by D-T fusion reaction were bombarded on the natural sample of Sb to induce radioactivity. A High Purity Germanium detector (HPGe) with a resolution of 2.1 keV at 1.33 MeV γ-ray energy of 60Co based on GENIE software was used for the counting of emitted gamma photo peaks. Calculated results are compared with the existing studies from EXFOR. The cross-section values are estimated using TALYS-2.0 statistical code by employing different input parameters, along with the latest Evaluated Nuclear data libraries (ENDF/B-VIII.0, JEFF-3.3). To obtain more precise data, uncertainties from various parameters are propagated using the correlation coefficients among all the parameters. This systematic detailed covariance analysis helps to reduce the present discrepancies and to refine the nuclear data.
- Publication type
- Journal Article MeSH
In cryo-electron microscopy, accurate particle localization and classification are imperative. Recent deep learning solutions, though successful, require extensive training datasets. The protracted generation time of physics-based models, often employed to produce these datasets, limits their broad applicability. We introduce FakET, a method based on neural style transfer, capable of simulating the forward operator of any cryo transmission electron microscope. It can be used to adapt a synthetic training dataset according to reference data producing high-quality simulated micrographs or tilt-series. To assess the quality of our generated data, we used it to train a state-of-the-art localization and classification architecture and compared its performance with a counterpart trained on benchmark data. Remarkably, our technique matches the performance, boosts data generation speed 750×, uses 33× less memory, and scales well to typical transmission electron microscope detector sizes. It leverages GPU acceleration and parallel processing. The source code is available at https://github.com/paloha/faket/.
Orthotopic tumor models in pre-clinical translational research are becoming increasingly popular, raising the demands on accurate tumor localization prior to irradiation. This task remains challenging both in x-ray and proton computed tomography (xCT and pCT, respectively), due to the limited contrast of tumor tissue compared to the surrounding tissue. We investigate the feasibility of gadolinium oxide nanoparticles as a multimodal contrast enhancement agent for both imaging modalities. We performed proton radiographies at the experimental room of the Trento Proton Therapy Center using a MiniPIX-Timepix detector and dispersions of gadolinium oxide nanoparticles in sunflower oil with mass fractions up to 8wt%. To determine the minimum nanoparticle concentration required for the detectability of small structures, pCT images of a cylindrical water phantom with cavities of varying gadolinium oxide concentration were simulated using a dedicated FLUKA Monte Carlo framework. These findings are complemented by simulating pCT at dose levels from 80 mGy to 320 mGy of artificially modified murine xCT data, mimicking different levels of gadolinium oxide accumulation inside a fictitious tumor volume. To compare the results obtained for proton imaging to x-ray imaging, cone-beam CT images of a cylindrical PMMA phantom with cavities of dispersions of oil and gadolinium oxide nanoparticles with mass fractions up to 8wt% were acquired at a commercial pre-clinical irradiation setup. For proton radiography, considerable contrast enhancement was found for a mass fraction of 4wt%. Slightly lower values were found for the simulated pCT images at imaging doses below 200 mGy. In contrast, full detectability of small gadolinium oxide loaded structures in xCT at comparable imaging dose is already achieved for 0.5wt%. Achieving such concentrations required for pCT imaging inside a tumor volume inin-vivoexperiments may be challenging, yet it might be feasible using different targeting and/or injection strategies.
- MeSH
- Phantoms, Imaging * MeSH
- Gadolinium * chemistry MeSH
- Contrast Media * chemistry MeSH
- Mice MeSH
- Nanoparticles * chemistry MeSH
- Tomography, X-Ray Computed MeSH
- Protons * MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
PURPOSE: With the increasing use of proton therapy, there is a growing emphasis on including radiation quality, often quantified by linear energy transfer, as a treatment plan optimization factor. The Timepix detectors offer energy-sensitive particle tracking useful for the characterization of proton linear energy transfer. To improve the detector's performance in mixed radiation fields produced in proton therapy, we customized the detector settings and performed the per-pixel energy calibration. METHODS: The detection threshold and per-pixel signal shaping time (IKrum current) were customized, and energy calibration was performed for MiniPIX Timepix3. The detector calibration was verified using α source and clinical proton beams, as well as Monte Carlo simulations. The effects on the detector's performance, in terms of spectral saturation and pixel occupancy, were evaluated. RESULTS: Measurements with proton beams showed a good agreement with simulations. With the customized settings, the measurable energy range in the detector data-driven mode was extended, and the signal duration time was reduced by 80%, while the yield of pixel time occupancy reduction depends on the number of occupied pixels. For performed measurements with proton beams, the number of occupied pixels was further reduced up to 40% due to the increased threshold. CONCLUSIONS: Customized detector configuration of the Timepix3 detector allowed for reduced pixel occupancy and mitigation of signal saturation in a data-driven mode without significantly interfering with the energy deposition measurement. The presented approach enables the extension of the operational range, including higher intensities and mixed-radiation fields in particle radiotherapy environments.
- MeSH
- Calibration MeSH
- Linear Energy Transfer MeSH
- Monte Carlo Method * MeSH
- Proton Therapy * instrumentation MeSH
- Publication type
- Journal Article MeSH
Due to their attractive band gap properties and van der Waals structure, 2D binary chalcogenide materials have been widely investigated in the last decade, finding applications in several fields such as catalysis, spintronics, and optoelectronics. Ternary 2D chalcogenide materials are a subject of growing interest in materials science due to their superior chemical tunability which endows tailored properties to the devices prepared thereof. In the family of AIIBIII2XVI4, ordered ZnIn2S4-like based photocatalytic systems have been studied meticulously. In contrast, reports on disordered phases appear to a minor extent. Herein, a photoelectrochemical (PEC) detector based on the pseudo-binary MnIn2Se4 system is presented. A combination of optical measurements and DFT calculations confirmed that the nature of the bandgap in MnIn2Se4 is indirect. Its performance outclasses that of parent compounds, reaching responsivity values of 8.41 mA W-1. The role of the non-centrosymmetric crystal structure is briefly discussed as a possible cause of improved charge separation of the photogenerated charge carriers.
- Publication type
- Journal Article MeSH
Background: In recent years, significant resistance of microorganisms to antibiotics has been observed. A biofilm is a structure that significantly aids the survival of the microbial population and also significantly affects its resistance. Methods: Thyme and clove essential oils (EOs) were subjected to chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Furthermore, the antimicrobial effect of these EOs was tested in both the liquid and vapor phases using the volatilization method. The effect of the EOs on growth parameters was monitored using an RTS-8 bioreactor. However, the effect of the EOs on the biofilm formation of commonly occurring bacteria with pathogenic potential was also monitored, but for less described and yet clinically important strains of Arcobacter spp. Results: In total, 37 and 28 compounds were identified in the thyme and clove EO samples, respectively. The most common were terpenes and also derivatives of phenolic substances. Both EOs exhibited antimicrobial activity in the liquid and/or vapor phase against at least some strains. The determined antimicrobial activity of thyme and clove oil was in the range of 32-1024 μg/mL in the liquid phase and 512-1024 μg/mL in the vapor phase, respectively. The results of the antimicrobial effect are also supported by similar conclusions from monitoring growth curves using the RTS bioreactor. The effect of EOs on biofilm formation differed between strains. Biofilm formation of Pseudomonas aeruginosa was completely suppressed in an environment with a thyme EO concentration of 1024 μg/mL. On the other hand, increased biofilm formation was found, e.g., in an environment of low concentration (1-32 μg/mL). Conclusions: The potential of using natural matrices as antimicrobials or preservatives is evident. The effect of these EOs on biofilm formation, especially Arcobacter strains, is described for the first time.
- Publication type
- Journal Article MeSH
BACKGROUND: FLASH radiotherapy necessitates the development of advanced Quality Assurance methods and detectors for accurate monitoring of the radiation field. This study introduces enhanced time-resolution detection systems and methods used to measure the delivered number of pulses, investigate temporal structure of individual pulses and dose-per-pulse (DPP) based on secondary radiation particles produced in the experimental room. METHODS: A 20 MeV electron beam generated from a linear accelerator (LINAC) was delivered to a water phantom. Ultra-high dose-per-pulse electron beams were used with a dose-per-pulse ranging from ̴ 1 Gy to over 7 Gy. The pulse lengths ranged from 1.18 μs to 2.88 μs at a pulse rate frequency of 5 Hz. A semiconductor pixel detector Timepix3 was used to track single secondary particles. Measurements were performed in the air, while the detector was positioned out-of-field at a lateral distance of 200 cm parallel with the LINAC exit window. The dose deposited was measured along with the pulse length and the nanostructure of the pulse. RESULTS: The time of arrival (ToA) of single particles was measured with a resolution of 1.56 ns, while the deposited energy was measured with a resolution of several keV based on the Time over Threshold (ToT) value. The pulse count measured by the Timepix3 detector corresponded with the delivered values, which were measured using an in-flange integrating current transformer (ICT). A linear response (R2 = 0.999) was established between the delivered beam current and the measured dose at the detector position (orders of nGy). The difference between the average measured and delivered pulse length was ∼0.003(30) μs. CONCLUSION: This simple non-invasive method exhibits no limitations on the delivered DPP within the range used during this investigation.
The middle colic artery usually arises from the superior mesenteric artery, but in rare cases it may arise from the coeliac trunk or its branches. The aim of this study was to investigate variant origins of the middle colic artery on computed tomography and anatomical dissection. Variant middle colic arteries were identified on computed tomography as part of an ongoing study investigating anatomical variations of vessels of the upper abdomen. Three-dimensional reconstructions were made to demonstrate the variant findings. Cadaveric dissections were performed as part of a routine dissection course. We report five cases of rare variant origins of the middle colic artery arising from the coeliac axis. Among these sites of origin were the coeliac trunk, the gastrosplenic trunk, the splenic artery, and the common hepatic artery. Four cases were identified on multi-detector computed tomography and one in a cadaver. In all cases, the vessels passed posterior to the body of the pancreas before entering the transverse mesocolon. Knowledge of middle colic artery variations is important to prevent inadvertent injury in digestive surgery, especially in the hepatopancreatic area. Variant origins of the middle colic artery are rare, and their knowledge is crucial to prevent unnecessary iatrogenic injury during abdominal surgery.
- MeSH
- Celiac Artery MeSH
- Hepatic Artery MeSH
- Mesenteric Artery, Inferior MeSH
- Mesenteric Artery, Superior * diagnostic imaging MeSH
- Colon, Transverse * MeSH
- Humans MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
