- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Current Status of Patient Radiation Exposure of Cardiac Positron Emission Tomography and Single-Photon Emission Computed Tomographic Myocardial Perfusion Imaging
摘要： BACKGROUND: Radiation exposure during nuclear cardiology procedures has received much attention and has prompted citations for radiation reduction. In 2010, the American Society of Nuclear Cardiology recommended reducing the average patient study radiation exposure to <9 mSv in 50% of studies by 2014. Cardiac positron emission tomography (PET) for myocardial perfusion imaging (MPI) has emerged within recent years, but current radiation exposure in cardiac nuclear PET laboratories is unknown. This study evaluated current reported patient radiation exposure from nuclear laboratories in the United States applying for Intersocietal Accreditation Commission accreditation for MPI using single photon emission computed tomography (SPECT) or PET. METHODS AND RESULTS: This was an analysis of nuclear cardiology studies submitted to the Intersocietal Accreditation Commission for either or both cardiac PET and SPECT accreditation. Cardiac SPECT data represented year 2015 while PET data combined years 2013 to 2015. Data was analyzed with χ2 and Mann-Whitney U tests (reported as median, 25th percentile, and 75th percentile). Reported PET MPI radiation exposure for 111 laboratories (532 patient cases) was 3.7 (3.2–4.1) mSv per study with no geographic variation. Reported SPECT MPI radiation exposure for 665 laboratories (3067 patient studies) was 12.8 (12.2–14.3) mSv. Highest radiation exposure was found in the South region. Technetium-only studies resulted in a median of 12.2 mSv per study. CONCLUSIONS: Radiation exposure from cardiac PET MPI in US laboratories applying for Intersocietal Accreditation Commission accreditation is low (111 laboratories, 3.7 mSv) and substantially lower than cardiac SPECT (665 laboratories, 12.8 mSv).
关键词： technetium,accreditation,myocardial perfusion imaging,positron emission tomography,radiation exposure
更新于2025-09-23 15:23:52
-
Detecting the Burns temperature in Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> -xBaTiO <sub/>3</sub> lead-free relaxor ferroelectrics by means of acoustic emission
摘要： Na0.5Bi0.5TiO3-xBaTiO3 ceramics samples (0 < x < 0.8) were studied by means of an acoustic emission method. The characteristic temperatures such as the Burns temperature, TB, the transition to paraelectric phase, Tp, the temperature maximum of the dielectric constant, Tm, and the intermediate temperature, T ? were detected and their dependences on x were plotted. Based on the comparison of the obtained data with the previously published ones, it is shown that the Burns temperature, TB, cannot be reliably determined by the deviation of the reverse dielectric constant, 1/ε(cid:3), from a straight line.
关键词： phase transitions,relaxor ferroelectrics,Na0.5Bi0.5TiO3-xBaTiO3,Burns temperature,acoustic emission
更新于2025-09-23 15:23:52
-
Angular-Dependent Spontaneous Emission in Cholesteric Liquid Crystal Films
摘要： Due to the presence of a selective reflection band, cholesteric liquid crystals (CLCs) strongly modify the emission of fluorescent guest molecules. While emission along the helical axis is well understood, the emission properties at oblique angles with respect to the cholesteric helix have so far have not been explored in detail. We present a systematic study of the angular-dependent spontaneous emission properties of dye-doped cholesteric films, including a full Stokes analysis of the emitted light. Variation of the cholesteric pitch allows us to probe the effect of the photonic band structure on spontaneous emission in a wide angular range. We find exceptional angular-dependent intensity and polarization variations of the emitted light, and give experimental proof for the splitting of the first-order reflection band as well as its overlap with the second-order band at large detection angles.
关键词： and Hybrid Materials,Optical,Cholesteric Liquid Crystal,Stokes Analysis,Angular-Dependent,Plasmonics,Spontaneous Emission,Magnetic
更新于2025-09-23 15:23:52
-
Improved immuno-PET imaging of HER2-positive tumors in mice: Urokinase injection-triggered clearance enhancement of <sup>64</sup> Cu-trastuzumab
摘要： Immuno-positron emission tomography (immuno-PET) is expected to improve the specificity of small chemical tracers such as 18F-fluorodeoxyglucose. Whole antibodies significantly accumulate in target molecule-expressing tumors but frequently persist too long in the blood circulation for imaging purposes. We investigated the utility of whole antibodies, 64Cu-labeled via a urokinase-substrate linker, and their exogenous urokinase-responsive cleavage to enhance clearance of immuno-PET probes from the blood and shorten the time required to develop adequate imaging contrast. Specifically, we used 64Cu-labeled trastuzumab in human epidermal growth factor receptor 2 (HER2)-positive tumor-bearing mice. 64Cu-labeled trastuzumab with a urokinase-cleavage site (64Cu-CB-TE1A1P-USL-trastuzumab) was synthesized using a bifunctional chelator incorporating a urokinase substrate peptide. Urokinase cleavage was analyzed in vitro by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and radio-gel permeation-high performance liquid chromatography. Improvements in radioisotope clearance and HER2-imaging by urokinase injection were evaluated by PET imaging and ex vivo biodistribution studies in A431 tumor-bearing mice. 64Cu-CB-TE1A1P-USL-trastuzumab was cleaved into smaller radioactive fragments by 20,000 IU/mL urokinase treatment in vitro at an efficacy of ~95%. The probe targeted HER2 in A431 tumors in mice within 24 h post-injection, and approximately two-thirds of the probe in the blood circulation was eliminated via renal clearance of radioactive fragments after three urokinase injections. Therefore, the tumor/blood ratio increased 3.0-fold. Without urokinase injection, the tumor accumulation of 64Cu-CB-TE1A1P-USL-trastuzumab slowly increased and the blood radioactivity decreased over 72 h. However, the tumor/blood ratios in mice after three urokinase injections were higher at 24 h than those in mice without injections at 72 h. The results indicate that our approach shortened the time required to develop adequate imaging contrast of immuno-PET by > 2 days. Therefore, this approach can benefit high-sensitivity imaging under lower radioactive decay conditions and can decrease patient radiation exposure. In addition, it could reduce other adverse effects of radioimmunotherapy.
关键词： immuno-positron emission tomography,cancer imaging,trastuzumab,urokinase,imaging contrast,clearance enhancement
更新于2025-09-23 15:23:52
-
Fabrication of Stable Carbon Nanotube Cold Cathode Electron Emitters with Post-Growth Electrical Aging
摘要： We fabricated carbon nanotube (CNT) cold cathode emitters with enhanced and stable electron emission properties and long-time stability with electrical aging as a post-treatment. Our CNT field emitters showed improved electrical properties by electrical aging. We set the applied bias for effective electrical aging, with the bias voltage defined at the voltage where Joule heating appeared. At the initial stage of aging, the electron emission current started to increase and then was saturated within 3 h. We understood that 5 h aging time was enough at proper aging bias. If the aging bias is higher, excessive heating damages CNT emitters. With the electrical aging, we obtained improved electron emission current from 3 mA to 6 mA. The current of 6 mA was steadily driven for 9 h.
关键词： carbon nanotube,electrical aging,electron emission,Joule heating,field emitters
更新于2025-09-23 15:23:52
-
Modular Ceramic-Polymeric Device for Analysis of Selected Elements in Liquid Using Microplasma
摘要： Miniaturization of devices for analysis of chemical composition is being still developed. In this article we present a portable device with a microplasma excitation source. The microdischarge is ignited inside a ceramic structure between a solid anode and a liquid cathode. As a result of cathode sputtering of the solution, it is possible to determine its chemical specimens by analysis of emission spectra of the microdischarge. We fabricated cathodes with a microfluidic compartment and two types of anodes. Devices were tested experimentally. Spectroscopic properties of the microdischarge and its analytical performance depended on the used ceramic structure, the surface area of the cathode aperture and the flow rate of the solution.
关键词： optical emission spectroscopy,microplasma,LTCC
更新于2025-09-23 15:23:52
-
Visualize Embryogenesis and Cell Fate Using Fluorescent Probes with Aggregation-Induced Emission
摘要： Horseradish peroxidase (HRP) and fluorogen-dextran conjugate are tracers extensively used for injection-based lineage tracing. However, HRP is sensitive to proteolytic digestion while the high-molecular-weight dextran may have antigenicity. Small molecular tracers can overcome these problems, but they usually diffuse from labeled cells, causing inaccurate information. Herein, we developed a small-molecular-weight fluorogen with aggregation-induced emission (AIEgen) for embryonic cell tracing with strong signals against tracer dilution caused by cell division. Once injected into the ancestor cells, the AIEgen can be entrapped in the cells without leakage because of the two hydrophilic and neutral arms. Consequently, it can specifically trace the progenies of the treated ancestor cells. More importantly, the operating concentration of AIEgen can be much higher than those of fluorogens with aggregation-caused quenching (ACQ), which provides bright signals in daughter cells during embryonic cell tracing, thus overcoming the problem of fast signal degrading typically encountered with the use of traditional cell tracers.
关键词： bright signals,small molecule,aggregation-induced emission,cell entrapped,embryonic cell,zebrafish lineage tracing
更新于2025-09-23 15:23:52
-
Circularly Polarized Luminescence from Chiral Conjugated Poly(carbazole-ran-acridine)s with Aggregation-Induced Emission and Delayed Fluorescence
摘要： Pure organic materials with circularly polarized luminescence (CPL) and delayed fluorescence have gained increasing interest from academic and technological areas. To enhance the solid-state emission and exciton utilization in chiral optoelectronic devices, a synthetic strategy to impart conjugated polymers with CPL and aggregation-induced delayed fluorescence was proposed. Herein, two conjugated macromolecules with electron-donating poly(carbazole-ran-acridine) backbones, electron-withdrawing dibenzothiophen-2-yl(phenyl)methanone and chiral alanine moieties were designed and synthesized. Their neat films exhibited strong green emission with quantum yields of 6.7% and 10.3% and delayed fluorescence with lifetime of 1.358 μs and 1.366 μs, respectively. Both Cotton effect and CPL with dissymmetry factor of –2.01 × 10–3 and –1.39 × 10–3 were determined in the solid state. Such unique conjugated polymers were employed as solution-processed emitting layers in organic light emitting diodes, which displayed maximum brightness of 1477 cd/m2 and maximum current efficiency of 2.52 cd/A.
关键词： OLEDs,conjugated polymers,aggregation-induced emission,delayed fluorescence,aggregation-induced delayed fluorescence,circularly polarized luminescence
更新于2025-09-23 15:23:52
-
Unprecedented Multicolor Photoluminescence from Hyperbranched Poly(amino ester)s
摘要： A novel kind of water-soluble fluorescent hyperbranched poly(amino ester) (PAE) is prepared through a one-pot polycondensation reaction of citric acid (CA) and N-methyldiethanolamine (NMDEA). The PAE exhibits enhanced and red-shift fluorescence with increasing solution concentration, showing distinct aggregation-induced emission character. Interestingly, the resulting PAE exhibits tunable photoluminescence from blue, cyan, and green to red irradiated by altering the excitation wavelengths. Such unique emission of non-conjugated PAE is attributed to the clustering of ester and tertiary amine groups derived from PAE self-assembly aggregates. Moreover, the fluorescence of PAE is very sensitive to Fe3+ ions. The facile preparation and unique optical features make PAE potentially useful in numerous applications such as multicolor cellular imaging, Fe3+ ions probe, and light-emitting diodes.
关键词： aggregation-induced emission,poly(amino ester)s,water-soluble polymers,hyperbranched,fluorescence
更新于2025-09-23 15:23:52
-
Rational Design of Near-Infrared AIE-Active Probes: In Situ Mapping of Amyloid-β Plaques with Ultra-Sensitivity and High-Fidelity
摘要： High-fidelity mapping of amyloid-β (Aβ) plaques is critical for the early detection of Alzheimer’s disease. However, in vivo probing of Aβ plaques by commercially available Thioflavin derivatives (ThT or ThS) has proven to be extremely limited, as evident by the restriction of enrichment quenching effect, low signal-to-noise (S/N) ratio and poor blood-brain barrier (BBB) penetrability. Herein, we demonstrate a rational design strategy of near-infrared (NIR) aggregation-induced emission (AIE)-active probes for Aβ plaques, through introducing lipophilic π-conjugated thiophene-bridge for extending to NIR wavelength with enhancement of BBB penetrability, and tuning the substituted position of sulfonate group for guaranteeing specific hydrophilicity to keep fluorescence-off state before binding to Aβ deposition. Probe QM-FN-SO3 has well settled the AIE dilemma between lipophilic requirement for longer emission and aggregation behavior from water to protein fibrillogenesis, thus making a breakthrough in high-fidelity feedback on in vivo detection of Aβ plaques with remarkable binding affinity, and serving as an efficient alternative to the commercial probe ThT or ThS.
关键词： Fluorescent probe,In vivo imaging,Aggregation-induced emission,Amyloid-β plaques,Near-infrared
更新于2025-09-23 15:23:52