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The Journal of Organic Chemistry Sep 2022A modular synthetic process enables two or four shielding arms to be appended strategically over the fluorochromes of near-infrared cyanine heptamethine dyes to create...
A modular synthetic process enables two or four shielding arms to be appended strategically over the fluorochromes of near-infrared cyanine heptamethine dyes to create hydrophilic analogs of clinically approved indocyanine green. A key synthetic step is the facile substitution of a heptamethine 4'-Cl atom by a phenol bearing two triethylene glycol chains. The lead compound is a heptamethine dye with four shielding arms, and a series of comparative spectroscopy studies showed that the shielding arms (a) increased dye photostability and chemical stability and (b) inhibited dye self-aggregation and association with albumin protein. In mice, the dye cleared from the blood primarily through the renal pathway rather than the biliary pathway for . This change in biodistribution reflects the much smaller hydrodynamic diameter of the shielded hydrophilic analog compared to the 67 kDa size of the /albumin complex. An attractive feature of versatile synthetic chemistry is the capability to systematically alter the dye's hydrodynamic diameter. The sterically shielded hydrophilic dye platform is well-suited for immediate incorporation into dynamic contrast-enhanced (DCE) spectroscopy or imaging protocols using the same cameras and detectors that have been optimized for .
Topics: Albumins; Animals; Fluorescent Dyes; Hydrophobic and Hydrophilic Interactions; Indocyanine Green; Mice; Tissue Distribution
PubMed: 35950971
DOI: 10.1021/acs.joc.2c01229 -
Journal of Medical Signals and Sensors 2022Nuclear medicine technicians would receive unavoidable exposures during the preparation and administration of radiopharmaceuticals. Based on the staff dose monitoring,...
Evaluation of Annual Staff Doses and Radiation Shielding Efficiencies of Thyroid Shield and Lead Apron during Preparation and Administration of I, Kr, and Tc-Labeled Radiopharmaceuticals.
Nuclear medicine technicians would receive unavoidable exposures during the preparation and administration of radiopharmaceuticals. Based on the staff dose monitoring, the dose reduction efficiencies of the radiation protection shields and the need to implement additional strategies to reduce the staff doses could be evaluated. In this study, medical staff doses during the preparation and administration of Tc-99 m, I-131, and Kr-81 radiopharmaceuticals were evaluated. The dose reduction efficiencies of the lead apron and thyroid shield were also investigated. GR-207 thermoluminescent dosimeter (TLD) chips were used for quantifying the medical staff doses. The occupational dose magnitudes were determined in five organs at risk including eye lens, thyroid, fingers, chest, and gonads. TLDs were located under and over the protective shields for evaluating the dose reduction efficiencies of the lead apron and thyroid shield. The occupational doses were normalized to the activities used in the working shifts. During preparation and injection of Tc-99 m radiopharmaceutical, the average annual doses were higher in the chest (4.49 mGy) and eye lenses (4 mGy). For I-131 radiopharmaceutical, the average annual doses of the point-finger (15.8 mGy) and eye lenses (1.23 mGy) were significantly higher than other organs. During the preparation and administration of Kr-81, the average annual doses of the point-finger (0.65 mGy) and chest (0.44 mGy) were higher. The significant dose reductions were achieved using the lead apron and thyroid shield. The radiation protection shields and minimum contact with the radioactive sources, including patients, are recommended to reduce the staff doses.
PubMed: 35265471
DOI: 10.4103/jmss.JMSS_45_20 -
Gut and Liver May 2022The worldwide coronavirus disease 2019 pandemic has led endoscopists to use personal protective equipment (PPE) for infection prevention. This study aimed to investigate...
BACKGROUND/AIMS
The worldwide coronavirus disease 2019 pandemic has led endoscopists to use personal protective equipment (PPE) for infection prevention. This study aimed to investigate whether wearing a face shield as PPE affects the quality of colonoscopy.
METHODS
We reviewed the medical records and colonoscopy findings of patients who underwent colonoscopies at Asan Medical Center, Korea from March 10 to May 31, 2020. The colonoscopies in this study were performed by five gastroenterology fellows and four expert endoscopists. We compared colonoscopy quality indicators, such as withdrawal time, adenoma detection rate (ADR), mean number of adenomas per colonoscopy (APC), polypectomy time, and polypectomy adverse events, both before and after face shields were added as PPE on April 13, 2020.
RESULTS
Of the 1,344 colonoscopies analyzed, 715 and 629 were performed before and after the introduction of face shields, respectively. The median withdrawal time was similar between the face shield and no-face shield groups (8.72 minutes vs 8.68 minutes, p=0.816), as was the ADR (41.5% vs 39.8%, p=0.605) and APC (0.72 vs 0.77, p=0.510). Polypectomy-associated quality indicators, such as polypectomy time and polypectomy adverse events were also not different between the groups. Quality indicators were not different between the face shield and no-face shield groups of gastroenterology fellows, or of expert endoscopists.
CONCLUSIONS
Colonoscopy performance was not unfavorably affected by the use of a face shield. PPE, including face shields, can be recommended without a concern about colonoscopy quality deterioration.
Topics: Adenoma; COVID-19; Colonoscopy; Colorectal Neoplasms; Early Detection of Cancer; Humans; Pandemics; Republic of Korea
PubMed: 34426561
DOI: 10.5009/gnl210063 -
Sensors (Basel, Switzerland) Apr 2022High-frequency electromagnetic induction (HFEMI) sensors, operating in the frequency range from 300 kHz to 30 MHz, have been proposed for the measurement of soil...
High-frequency electromagnetic induction (HFEMI) sensors, operating in the frequency range from 300 kHz to 30 MHz, have been proposed for the measurement of soil electrical conductivity and dielectric permittivity that are related to the physical and chemical properties of soil. Because of the high-frequency operation, the capacitive coupling between the sensor transmitter and receiver coils is comparable to inductive coupling, creating the need for electrostatic shielding. The remnant capacitive coupling after the implementation of shielding can lead to significant difficulties in the sensor signal interpretation, because both coupling mechanisms are highly dependent on the geometry of the HFEMI sensor and applied shield. In this paper, we introduce the discussion on the relationship between the sensor geometry, shielding and the coupling mechanisms for HFEMI soil sensing. We theoretically and experimentally evaluate a typical HFEMI sensor and its shielding in the frequency range of up to 20 MHz and propose a method for evaluating the effectiveness of a shield configuration. In the case study, we experimentally analyze the HFEMI sensor above a saline solution for two shield configurations. The results agree well with the results of a finite element method analysis.
PubMed: 35458987
DOI: 10.3390/s22083000 -
BMC Oral Health Apr 2022Tooth extraction is often followed by remodeling of hard and soft tissues, while socket shield technique has been proposed to prevent or minimize this remodeling. Socket...
BACKGROUND
Tooth extraction is often followed by remodeling of hard and soft tissues, while socket shield technique has been proposed to prevent or minimize this remodeling. Socket shield accompanied with delayed implant placement is a novel technique that could be used when delayed implantation is selected; however, more scientific based evidence is required to recommend this technique as everyday clinical practice. Thus, the aim of this case series was to assess the clinical, radiographic, and esthetic outcomes of the delayed placed implants associated with previously prepared socket shield at 3-15 months follow-up after loading. The stability of the shield and the depth of soft tissue penetration palatal to the shield at reentry of 3-6 months were also assessed.
CASES PRESENTATION
Five case reports of socket shield with delayed implant placement were described in the study. The facial shields were prepared and simultaneously the sockets were grafted with mineralized allograft particles, then the implants were placed 3-6 months later. Periodontal probe was used to measure the depth of soft tissue penetration palatal to the shield at reentry. Clinical indices of bleeding index, plaque index, and probing depths were recorded. Radiographic evaluation to record the amount of marginal bone loss post-loading, esthetic assessment using modified pink esthetic score, and patient assessed outcomes were also evaluated at 3-15 months follow-up after loading. At 3-6 months reentry, all shields were stable with maintenance of the facial bone and with extreme hard tissue formation in the sockets. All five implants were successful and functional without any pain or inflammation, with optimal soft tissue health and esthetics, and with minimal radiographic marginal bone loss at the last follow-up visit (3-15 months after loading).
CONCLUSIONS
Within the limits of this study, socket shield technique with delayed implant placement could be a predictable minimally invasive option for cases requiring delayed implant placement; however, a long-term well-designed clinical proof is warranted.
Topics: Dental Implants; Dental Implants, Single-Tooth; Esthetics, Dental; Humans; Immediate Dental Implant Loading; Maxilla; Tooth Extraction; Tooth Socket; Treatment Outcome
PubMed: 35382808
DOI: 10.1186/s12903-022-02149-7 -
Dento Maxillo Facial Radiology 2016To evaluate the utility of the application of a thyroid shield in intraoral radiography when using rectangular collimation.
OBJECTIVES
To evaluate the utility of the application of a thyroid shield in intraoral radiography when using rectangular collimation.
METHODS
Experimental data were obtained by measuring the absorbed dose at the position of the thyroid gland in a RANDO(®) (The Phantom Laboratory, Salem, NY) male phantom with a dosemeter. Four protocols were tested: round collimation and rectangular collimation, both with and without thyroid shield. Five exposure positions were deployed: upper incisor (Isup), upper canine (Csup), upper premolar (Psup), upper molar (Msup) and posterior bitewing (BW). Exposures were made with 70 kV and 7 mA and were repeated 10 times. The exposure times were as recommended for the exposure positions for the respective collimator type by the manufacturer for digital imaging. The data were statistically analyzed with a three-way ANOVA test. Significance was set at p < 0.01.
RESULTS
The ANOVA test revealed that the differences between mean doses of all protocols and geometries were statistically significant, p < 0.001. For the Isup, thyroid dose levels were comparable with both collimators at a level indicating primary beam exposure. Thyroid shield reduced this dose with circa 75%. For the Csup position, round collimation also revealed primary beam exposure, and thyroid shield yield was 70%. In Csup with rectangular collimation, the thyroid dose was reduced with a factor 4 compared with round collimation and thyroid shield yielded an additional 42% dose reduction. The thyroid dose levels for the Csup, Psup, Msup and BW exposures were lower with rectangular collimation without thyroid shield than with round collimation with thyroid shield. With rectangular collimation, the thyroid shield in Psup, Msup and BW reduced the dose 10% or less, where dose levels were already low, implying no clinical significance.
CONCLUSIONS
For the exposures in the upper anterior region, thyroid shield results in an important dose reduction for the thyroid. For the other exposures, thyroid shield augments little to the reduction achieved by rectangular collimation. The use of thyroid shield is to be advised, when performing upper anterior radiography.
Topics: Humans; Protective Devices; Radiation Protection; Radiography, Dental; Thyroid Gland
PubMed: 27008105
DOI: 10.1259/dmfr.20150407 -
Scientific Reports Sep 2023Transnasal flexible laryngoscopy is considered an aerosol generating procedure. A negative pressure face shield (NPFS) was developed to control aerosol from the patient...
Transnasal flexible laryngoscopy is considered an aerosol generating procedure. A negative pressure face shield (NPFS) was developed to control aerosol from the patient during laryngoscopy. The purpose of this study was to determine the effectiveness of the NPFS at controlling virus aerosol compared to a standard disposable plastic face shield. The face shields were placed on a simulated patient coughing machine. MS2 bacteriophage was used as a surrogate for SARS-CoV-2 and was aerosolized using the coughing machine. The aerosolized virus was sampled on the inside and outside of the face shields. The virus aerosol concentration was not significantly different between the inside and outside of the traditional plastic face shield (p = 0.12). However, the particle concentrations across all particle sizes measured were significantly decreased outside the face shield. The virus and particle concentrations were significantly decreased (p < 0.01) outside the NPFS operating at a flow rate of 38.6 L per minute (LPM). When the NPFS was operated at 10 LPM, virus concentrations were not significantly different (p = 0.09) across the face shield. However, the number particle concentrations across all particle sizes measured were significantly different (p < 0.05).
Topics: Humans; COVID-19; SARS-CoV-2; Respiratory Aerosols and Droplets; Cough; Laryngoscopy
PubMed: 37730888
DOI: 10.1038/s41598-023-42403-8 -
Biomedical Journal Oct 2019To quantify image quality and radiation doses in regions adjacent to and distant from bismuth shields in computed tomography (CT).
BACKGROUND
To quantify image quality and radiation doses in regions adjacent to and distant from bismuth shields in computed tomography (CT).
METHODS
An American College of Radiology accreditation phantom with four solid rods embedded in a water-like background was scanned to verify CT number (CTN) accuracy when using bismuth shields. CTNs, image noise, and contrast-to-noise ratios (CNRs) were determined in the phantom at 80-140 kVp. Image quality was investigated on image portions in the zones adjacent (A zone) to and distant (D zone) from a bismuth shield. Surface radiation doses were measured using thermoluminescent dosimeters. Streak artefacts were graded on a 3-point-scale.
RESULTS
Changes in CTN caused by a bismuth shield resulted in changes in X-ray spectra. CTN changes were more apparent in the A zone than in the D zone, particularly for a low tube voltage. The degrees of CTN changes and image noise were proportional to the thickness of the bismuth shields. A 1-ply bismuth shield reduced surface radiation doses by 7.2%-15.5%. The overall CNRs were slightly degraded, and streak artefacts were acceptable.
CONCLUSIONS
Using a bismuth shield could result in significant CTN changes and perceivable artefacts, particularly for a superficial organ close to the shield, and is not recommended for quantification CT examinations or follow-up CT examinations.
Topics: Artifacts; Bismuth; Breast; Humans; Phantoms, Imaging; Radiation Dosage; Tomography, X-Ray Computed
PubMed: 31783995
DOI: 10.1016/j.bj.2019.04.004 -
European Radiology Apr 2024The aim of the patient out-of-plane shield is to reduce the patient radiation dose. Its effect on tube current modulation was evaluated with the out-of-plane shield...
OBJECTIVES
The aim of the patient out-of-plane shield is to reduce the patient radiation dose. Its effect on tube current modulation was evaluated with the out-of-plane shield visible in the localizer but absent in the scan range in chest CT with different CT scanners.
METHODS
An anthropomorphic phantom was scanned with six different CT scanners from three different vendors. The chest was first scanned without any shielding, and then with the out-of-plane shield within the localizer but outside the imaged volume. All pitch values of each scanner were used. The tube current values with and without the out-of-plane shield were collected and used to evaluate the effect of overscanning and tube current modulation (TCM) on patient radiation dose.
RESULTS
The highest increase in cumulative mA was 217%, when the pitch was 1.531. The tube current value increased already 8.9 cm before the end of the scanned anatomy and the difference between the tube current of the last slices (with and without the out-of-plane shield in the localizer) was 976%.
CONCLUSION
Applying an out-of-plane shield outside the scanned volume but visible in the localizer images may increase the patient dose considerably if the scanner's TCM function is based only on localizer images.
CLINICAL RELEVANCE STATEMENT
The use of an out-of-plane shield in CT may strongly increase the tube current modulation and thus provide the patient with a higher radiation dose.
KEY POINTS
• Applying an out-of-plane shield outside the scanned volume but visible in the localizer images may increase patient radiation dose considerably. • The effect is visible with scanners that use solely localizer-based tube current modulation. • Features like overscanning may be difficult for the user to notice when planning the scanning, and yet they may affect tube current modulation and through it to patient dose.
Topics: Humans; Radiation Dosage; Tomography, X-Ray Computed; Tomography Scanners, X-Ray Computed; Thorax; Phantoms, Imaging
PubMed: 37707547
DOI: 10.1007/s00330-023-10211-3 -
Scientific Reports Aug 2022Magnetically shielded rooms (MSRs) use multiple layers of materials such as MuMetal to screen external magnetic fields that would otherwise interfere with high precision...
Magnetically shielded rooms (MSRs) use multiple layers of materials such as MuMetal to screen external magnetic fields that would otherwise interfere with high precision magnetic field measurements such as magnetoencephalography (MEG). Optically pumped magnetometers (OPMs) have enabled the development of wearable MEG systems which have the potential to provide a motion tolerant functional brain imaging system with high spatiotemporal resolution. Despite significant promise, OPMs impose stringent magnetic shielding requirements, operating around a zero magnetic field resonance within a dynamic range of ± 5 nT. MSRs developed for OPM-MEG must therefore effectively shield external sources and provide a low remnant magnetic field inside the enclosure. Existing MSRs optimised for OPM-MEG are expensive, heavy, and difficult to site. Electromagnetic coils are used to further cancel the remnant field inside the MSR enabling participant movements during OPM-MEG, but present coil systems are challenging to engineer and occupy space in the MSR limiting participant movements and negatively impacting patient experience. Here we present a lightweight MSR design (30% reduction in weight and 40-60% reduction in external dimensions compared to a standard OPM-optimised MSR) which takes significant steps towards addressing these barriers. We also designed a 'window coil' active shielding system, featuring a series of simple rectangular coils placed directly onto the walls of the MSR. By mapping the remnant magnetic field inside the MSR, and the magnetic field produced by the coils, we can identify optimal coil currents and cancel the remnant magnetic field over the central cubic metre to just |B|= 670 ± 160 pT. These advances reduce the cost, installation time and siting restrictions of MSRs which will be essential for the widespread deployment of OPM-MEG.
Topics: Brain; Functional Neuroimaging; Humans; Magnetic Fields; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Magnetoencephalography
PubMed: 35945239
DOI: 10.1038/s41598-022-17346-1