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Current Opinion in Chemical Biology Oct 2023The long luminescence lifetimes and sharp emission bands of luminescent lanthanide complexes have long been recognized as invaluable strengths for sensing and imaging in... (Review)
Review
The long luminescence lifetimes and sharp emission bands of luminescent lanthanide complexes have long been recognized as invaluable strengths for sensing and imaging in complex aqueous biological or environmental media. Herein we discuss the recent developments of these probes for sensing metal ions and, increasingly, anions. Underappreciated in the field, buffers and metal hydrolysis influence the response of many responsive lanthanide probes. The inherent complexities arising from these interactions are further discussed.
Topics: Lanthanoid Series Elements; Luminescence; Cations; Anions; Luminescent Measurements
PubMed: 37517109
DOI: 10.1016/j.cbpa.2023.102374 -
Medicina Clinica Apr 2024Technological advances imply an increase in artificially generating sources of electromagnetic fields (EMF), therefore, resulting in a permanent exposure of people and... (Review)
Review
Technological advances imply an increase in artificially generating sources of electromagnetic fields (EMF), therefore, resulting in a permanent exposure of people and the environment (electromagnetic pollution). Inconsistent results have been published considering the evaluated health effects. The purpose of this study was to review scientific literature on EMF to provide a global and retrospective perspective, on the association between human exposure to non-ionizing radiation (NIR, mainly radiofrequency-EMF) and health and environmental effects. Studies on the health effects of 5G radiation exposure have not yet been performed with sufficient statistical power, as the exposure time is still relatively short and also the latency and intensity of exposure to 5G. The safety standards only consider thermal effects, do not contemplate non-thermal effects. We consider relevant to communicate this knowledge to the general public to improve education in this field, and to healthcare professionals to prevent diseases that may result from RF-EMF exposures.
Topics: Humans; Environmental Exposure; Retrospective Studies; Electromagnetic Fields; Radio Waves
PubMed: 38151370
DOI: 10.1016/j.medcli.2023.11.011 -
Journal of Synchrotron Radiation Nov 2023Microbeam radiation therapy (MRT) is a radiotherapy technique combining spatial fractionation of the dose distribution on a micrometric scale, X-rays in the 50-500 keV...
Microbeam radiation therapy (MRT) is a radiotherapy technique combining spatial fractionation of the dose distribution on a micrometric scale, X-rays in the 50-500 keV range and dose rates up to 16 × 10 Gy s. Nowadays, in vivo dosimetry remains a challenge due to the ultra-high radiation fluxes involved and the need for high-spatial-resolution detectors. The aim here was to develop a striped diamond portal detector enabling online microbeam monitoring during synchrotron MRT treatments. The detector, a 550 µm bulk monocrystalline diamond, is an eight-strip device, of height 3 mm, width 178 µm and with 60 µm spaced strips, surrounded by a guard ring. An eight-channel ASIC circuit for charge integration and digitization has been designed and tested. Characterization tests were performed at the ID17 biomedical beamline of the European Synchrotron Radiation Facility (ESRF). The detector measured direct and attenuated microbeams as well as interbeam fluxes with a precision level of 1%. Tests on phantoms (RW3 and anthropomorphic head phantoms) were performed and compared with simulations. Synchrotron radiation measurements were performed on an RW3 phantom for strips facing a microbeam and for strips facing an interbeam area. A 2% difference between experiments and simulations was found. In more complex geometries, a preliminary study showed that the absolute differences between simulated and recorded transmitted beams were within 2%. Obtained results showed the feasibility of performing MRT portal monitoring using a microstriped diamond detector. Online dosimetric measurements are currently ongoing during clinical veterinary trials at ESRF, and the next 153-strip detector prototype, covering the entire irradiation field, is being finalized at our institution.
Topics: Synchrotrons; Radiometry; Dose Fractionation, Radiation; X-Rays; Phantoms, Imaging; Radiotherapy; Monte Carlo Method; Diamond
PubMed: 37815374
DOI: 10.1107/S160057752300752X -
Magma (New York, N.Y.) Jul 2023Low-field MRI systems are expected to cause less RF heating in conventional interventional devices due to lower Larmor frequency. We systematically evaluate RF-induced...
OBJECTIVE
Low-field MRI systems are expected to cause less RF heating in conventional interventional devices due to lower Larmor frequency. We systematically evaluate RF-induced heating of commonly used intravascular devices at the Larmor frequency of a 0.55 T system (23.66 MHz) with a focus on the effect of patient size, target organ, and device position on maximum temperature rise.
MATERIALS AND METHODS
To assess RF-induced heating, high-resolution measurements of the electric field, temperature, and transfer function were combined. Realistic device trajectories were derived from vascular models to evaluate the variation of the temperature increase as a function of the device trajectory. At a low-field RF test bench, the effects of patient size and positioning, target organ (liver and heart) and body coil type were measured for six commonly used interventional devices (two guidewires, two catheters, an applicator and a biopsy needle).
RESULTS
Electric field mapping shows that the hotspots are not necessarily localized at the device tip. Of all procedures, the liver catheterizations showed the lowest heating, and a modification of the transmit body coil could further reduce the temperature increase. For common commercial needles no significant heating was measured at the needle tip. Comparable local SAR values were found in the temperature measurements and the TF-based calculations.
CONCLUSION
At low fields, interventions with shorter insertion lengths such as hepatic catheterizations result in less RF-induced heating than coronary interventions. The maximum temperature increase depends on body coil design.
Topics: Humans; Heating; Radio Waves; Magnetic Resonance Imaging; Temperature; Phantoms, Imaging; Hot Temperature
PubMed: 37195365
DOI: 10.1007/s10334-023-01099-7 -
Magma (New York, N.Y.) Jul 2023To review the major hardware components of low-field point-of-care MRI systems which affect the overall sensitivity. (Review)
Review
OBJECTIVE
To review the major hardware components of low-field point-of-care MRI systems which affect the overall sensitivity.
METHODS
Designs for the following components are reviewed and analyzed: magnet, RF coils, transmit/receive switches, preamplifiers, data acquisition system, and methods for grounding and mitigating electromagnetic interference.
RESULTS
High homogeneity magnets can be produced in a variety of different designs including C- and H-shaped as well as Halbach arrays. Using Litz wire for RF coil designs enables unloaded Q values of ~ 400 to be reached, with body loss representing about 35% of the total system resistance. There are a number of different schemes to tackle issues arising from the low coil bandwidth with respect to the imaging bandwidth. Finally, the effects of good RF shielding, proper electrical grounding, and effective electromagnetic interference reduction can lead to substantial increases in image signal-to-noise ratio.
DISCUSSION
There are many different magnet and RF coil designs in the literature, and to enable meaningful comparisons and optimizations to be performed it would be very helpful to determine a standardized set of sensitivity measures, irrespective of design.
Topics: Point-of-Care Systems; Magnetic Resonance Imaging; Radio Waves; Signal-To-Noise Ratio; Phantoms, Imaging; Equipment Design
PubMed: 37202656
DOI: 10.1007/s10334-023-01100-3 -
Magnetic Resonance in Medicine Mar 2024In any MR experiment, the bulk magnetization acts on itself, caused by the induced current in the RF receiver circuit that generates an oscillating damping field. This...
PURPOSE
In any MR experiment, the bulk magnetization acts on itself, caused by the induced current in the RF receiver circuit that generates an oscillating damping field. This effect, known as "radiation damping" (RD), is usually weak and, therefore, unconsidered in MRI, but can affect quantitative studies performed with dedicated coils that provide a high SNR. The current work examined RD in a setup for investigations of small tissue specimens including a quantitative characterization of the spin-coil system.
THEORY AND METHODS
A custom-made Helmholtz coil (radius and spacing 16 mm) was interfaced to a transmit-receive (Tx/Rx) switch with integrated passive feedback for modulation or suppression of RD similar to preamplifier decoupling. Pulse sequences included pulse-width arrays to demonstrate the absence/ presence of RD and difference techniques employing gradient pulses or composite RF pulses to quantify RD effects during free precession and transmission, respectively. Experiments were performed at 3T in small samples of MnCl solution.
RESULTS
Significant RD effects may impact RF pulse application and evolution periods. Effective damping time constants were comparable to typical T * times or echo spacings in multi-echo sequences. Measurements of the phase relation showed that deviations from the commonly assumed 90° angle between the damping field and the transverse magnetization may occur.
CONCLUSION
Radiation damping may affect the accuracy of quantitative MR measurements performed with dedicated RF coils. Efficient mitigation can be achieved hardware-based or by appropriate consideration in the pulse sequence.
Topics: Magnetic Resonance Imaging; Radio Waves; Phantoms, Imaging
PubMed: 38010072
DOI: 10.1002/mrm.29934 -
Life Sciences in Space Research Aug 2023In the last decade, NASA and other space exploration organizations have focused on making crewed missions to different locations in our solar system a priority. To...
In the last decade, NASA and other space exploration organizations have focused on making crewed missions to different locations in our solar system a priority. To ensure the crew members' safety in a harsh radiation environment outside the protection of the geomagnetic field and atmosphere, a robust radiation protection system needs to be in place. Passive shielding methods, which use mass shielding, are insufficient as a standalone means of radiation protection for long-term deep-space missions. Active shielding methods, which use electromagnetic fields to deflect charged particles, have the potential to be a solution that can be used along with passive shielding to make deep-space travel safer and more feasible. Past active shielding studies have demonstrated that substantial technological advances are required for active shielding to be a reality. However, active shielding has shown potential for near-future implementation when used to protect against solar energetic particles, which are less penetrating than galactic cosmic rays (GCRs). This study uses a novel approach to investigate the impacts of passive and active shielding for protection against extreme solar particle events (SPEs) and free-space GCR spectra under solar minimum and solar maximum conditions. Hybrid shielding configuration performance is assessed in terms of effective dose and radiobiological effectiveness (RBE)-weighted dose reduction. A novel electrostatic shielding configuration consisting of multiple charged planes and charged rods was chosen as the base active shielding configuration. After a rigorous optimization process, two hybrid shielding configurations were chosen based on their ability to reduce RBE-weighted dose and effective dose. For protection against the extreme SPE, a hybrid active-passive shielding configuration was chosen, where active shielding was placed outside of passive shielding. In the case of GCRs, to gain additional reduction compared to passive shielding, the passive shielding configuration was placed before the active shielding to intentionally fragment HZE ions to improve shielding performance.
Topics: Atmosphere; Cosmic Radiation; Electromagnetic Fields; Protective Devices; Radiation Protection; Humans
PubMed: 37481310
DOI: 10.1016/j.lssr.2023.04.004 -
Nano Letters Sep 2023Miniature two-photon microscopy has emerged as a powerful technique for investigating brain activity in freely moving animals. Ongoing research objectives include...
Miniature two-photon microscopy has emerged as a powerful technique for investigating brain activity in freely moving animals. Ongoing research objectives include reducing probe weight and minimizing animal behavior constraints caused by probe attachment. Employing dielectric metalenses, which enable the use of sizable optical components in flat device structures while maintaining imaging resolution, is a promising solution for addressing these challenges. In this study, we designed and fabricated a titanium dioxide metalens with a wavelength of 920 nm and a high aspect ratio. Furthermore, a meta-optic two-photon microscope weighing 1.36 g was developed. This meta-optic probe has a lateral resolution of 0.92 μm and an axial resolution of 18.08 μm. Experimentally, two-photon imaging of mouse brain structures in vivo was also demonstrated. The flat dielectric metalens technique holds promising opportunities for high-performance integrated miniature nonlinear microscopy and endomicroscopy platforms in the biomedical field.
Topics: Animals; Mice; Microscopy; Optical Devices; Photons
PubMed: 37651617
DOI: 10.1021/acs.nanolett.3c02439 -
Journal of Applied Clinical Medical... Mar 2024This report covers clinical implementation of a low kV intraoperative radiation therapy (IORT) program with the INTRABEAM® System (Carl Zeiss Meditec AG, Jena,... (Review)
Review
This report covers clinical implementation of a low kV intraoperative radiation therapy (IORT) program with the INTRABEAM® System (Carl Zeiss Meditec AG, Jena, Germany). Based on collective user experience from eight institutions, we discuss best methods of INTRABEAM quality assurance (QA) tests, commissioning measurements, clinical workflow, treatment planning, and potential avenues for research. The guide provides pertinent background information and clinical justification for IORT. It describes the INTRABEAM system and commissioning measurements along with a TG100 risk management analysis to ensure safety and accuracy of the IORT program. Following safety checks, dosimetry measurements are performed for verification of field flatness and symmetry, x-ray output, and depth dose. Also discussed are dose linearity checks, beam isotropy, ion chamber measurements, calibration protocols, and in-vivo dosimetry with optically stimulated luminescence dosimeters OSLDs, and radiochromic film. Emphasis is placed on the importance of routine QA procedures (daily, monthly, and annual) performed at regular intervals for a successful IORT program. For safe and accurate dose delivery, tests of important components of IORT clinical workflow are emphasized, such as, dose prescription, pre-treatment QA, treatment setup, safety checks, radiation surveys, and independent checks of delivered dose. Challenges associated with in-vivo dose measurements are discussed, along with special treatment procedures and shielding requirements. The importance of treatment planning in IORT is reviewed with reference to a Monte Carlo-based commercial treatment planning system highlighting its main features and limitations. The report concludes with suggested topics for research including CT-based image-guided treatment planning and improved prescription dose accuracy. We hope that this multi-institutional report will serve as a guidance document on the clinical implementation and use of INTRABEAM IORT.
Topics: Humans; X-Rays; Radiometry; Radiography; Radiotherapy Planning, Computer-Assisted; In Vivo Dosimetry; Radiotherapy Dosage; Multicenter Studies as Topic
PubMed: 38279520
DOI: 10.1002/acm2.14272 -
Instant water toxicity detection based on magnetically-constructed electrochemically active biofilm.Biosensors & Bioelectronics Dec 2023Water toxicity determination with electrochemically active bacteria (EAB) is promising in the early warning of water pollution. However, limited by tedious biofilm...
Water toxicity determination with electrochemically active bacteria (EAB) is promising in the early warning of water pollution. However, limited by tedious biofilm formation, natural EAB biofilms are uncapable of the instant detection of water toxicity, resulting in the failure for the emergency monitoring of water pollution. To solve this problem, a novel method for the rapid construction of EAB biofilms using magnetic adsorption was established, and the performance of instant water toxicity detection with magnetically-constructed EAB biofilm was investigated. The results demonstrate that EAB biofilms were magnetically constructed in less than 30 min, and magnetically-constructed EAB biofilm generated stable currents even under continuous flow conditions. Magnetically-constructed EAB biofilms realized instant water toxicity detection, and the sensitivity increased with the decrease of magnetic field intensity. Low magnetic field intensity resulted in a loose biofilm structure, which is conducive to toxic pollutant penetration. The detection limit for Cu, phenol, and Cd achieved 0.07 mg/L with optimal magnetic field intensity, and the detection time was less than 30 min. This study broadens the application of water toxicity determination with EAB, and establishes a foundation for the instant and continuous detection of water toxicity with EAB.
Topics: Water; Biosensing Techniques; Biofilms; Light; Bacteria
PubMed: 37832348
DOI: 10.1016/j.bios.2023.115745