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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Photovoltaic Inverter Momentary Cessation: Recovery Process is Key
摘要： Positron emission tomography (PET) images are typically reconstructed with an in-plane pixel size of approximately 4 mm for cancer imaging. The objective of this work was to evaluate the effect of using smaller pixels on general oncologic lesion-detection. A series of observer studies was performed using experimental phantom data from the Utah PET Lesion Detection Database, which modeled whole-body FDG PET cancer imaging of a 92 kg patient. The data comprised 24 scans over 4 days on a Biograph mCT time-of-flight (TOF) PET/CT scanner, with up to 23 lesions (diam. 6–16 mm) distributed throughout the phantom each day. Images were reconstructed with 2.036 mm and 4.073 mm pixels using ordered-subsets expectation-maximization (OSEM) both with and without point spread function (PSF) modeling and TOF. Detection performance was assessed using the channelized non-prewhitened numerical observer with localization receiver operating characteristic (LROC) analysis. Tumor localization performance and the area under the LROC curve were then analyzed as functions of the pixel size. In all cases, the images with ～2 mm pixels provided higher detection performance than those with ～4 mm pixels. The degree of improvement from the smaller pixels was larger than that offered by PSF modeling for these data, and provided roughly half the benefit of using TOF. Key results were confirmed by two human observers, who read subsets of the test data. This study suggests that a significant improvement in tumor detection performance for PET can be attained by using smaller voxel sizes than commonly used at many centers. The primary drawback is a 4-fold increase in reconstruction time and data storage requirements.
关键词： Image quality assessment,PET/CT reconstruction,PET/CT,image reconstruction
更新于2025-09-19 17:13:59
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PET/CT imaging with a <sup>18</sup> F-labeled galactodendritic unit in a galectin-1 overexpressing orthotopic bladder cancer model
摘要： Galectins are carbohydrate-binding proteins overexpressed in bladder cancer (BCa) cells. Dendritic galactose moieties have a high affinity for galectin-expressing tumor cells. We radiolabeled a dendritic galactose carbohydrate with fluorine-18 – 18F-labeled galactodendritic unit 4 – and examined its potential in imaging urothelial malignancies. Methods: The 18F-labeled 1st generation galactodendritic unit 4 was obtained from its tosylate precursor. We conducted in vivo studies in galectin-expressing UMUC3 orthotopic BCa model to determine the ability of 18F-labeled galactodendritic unit 4 to image BCa. Results: Intravesical administration of 18F-labeled galactodendritic unit 4 allowed specific accumulation of the carbohydrate radiotracer in galectin-1 overexpressing UMUC3 orthotopic tumors when imaged with PET. The 18F-labeled galactodendritic unit 4 was not found to accumulate in non-tumor murine bladders. Conclusion: The 18F-labeled galactodendritic unit 4 and similar analogs may be clinically relevant and exploitable for PET imaging of galectin-1 overexpressing bladder tumors.
关键词： PET/CT imaging,bladder cancer,18F-radiochemistry,galectins,dendritic carbohydrate
更新于2025-09-19 17:13:59
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Flexible high-efficiency CZTSSe solar cells on diverse flexible substrates via an adhesive-bonding transfer method
摘要： Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells are showing great promise due to using earth-abundant and non-toxic materials and tuning the bandgap through the amount of S and Se. Flexible high-efficiency CZTSSe solar cells are one of the outstanding research challenges because they currently require the use of thick glass substrates due to the high-temperature heat treatment process, and for this reason, few flexible CZTSSe solar cells have been reported. Furthermore, most researchers have used thin glass and metal substrates with little flexibility; the power conversion efficiency (PCE or ?) values of the solar cells made with them have been somewhat lower. To overcome these hurdles, we transferred high-efficiency CZTSSe solar cells formed on a soda-lime glass substrate to flexible substrates via an adhesive-bonding transfer method. Via this method, we were able to achieve the PCE of 5.8 to 7.1% on completely flexible substrates such as cloth, paper, and polyethylene terephthalate (PET). In particular, we were able to produce a CZTSSe solar cell on a PET substrate with a PCE of 7.1%, which is the highest among fully-flexible CZTSSe solar cells currently known to us. In addition, we deeply analyzed the PCE degradation of the flexible CZTSSe solar cell fabricated by the transfer method through a panoramic focused ion-beam image and nanoindentation. From the results of our work, we provide an insight into the possibility of making flexible high-efficiency CZTSSe solar cells using our transfer method.
关键词： thin-film solar cell,transfer method,polyethylene terephthalate (PET),Cu2ZnSn(S,Se)4 (CZTSSe),diverse flexible substrates
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Micro-Transfer Printer-Assembled Five Junction CPV Microcell Development
摘要： Quantitative analysis of positron emission tomography (PET) brain imaging data requires a metabolite-corrected arterial input function (AIF) for estimation of distribution volume and related outcome measures. Collecting arterial blood samples adds risk, cost, measurement error, and patient discomfort to PET studies. Minimally invasive AIF estimation is possible with simultaneous estimation (SIME), but at least one arterial blood sample is necessary. In this study, we describe a noninvasive SIME (nSIME) approach that utilizes a pharmacokinetic input function model and constraints derived from machine learning applied to an electronic health record database consisting of “long tail” data (digital records, paper charts, and handwritten notes) that were collected ancillary to the PET studies. We evaluated the performance of nSIME on 95 [11C]DASB PET scans that had measured AIFs. The results indicate that nSIME is a promising alternative to invasive AIF measurement. The general framework presented here may be expanded to other metabolized radioligands, potentially enabling quantitative analysis of PET studies without blood sampling. A glossary of technical abbreviations is provided at the end of this paper.
关键词： Arterial input function (AIF),positron emission tomography (PET) imaging,electronic health record (EHR)
更新于2025-09-19 17:13:59
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Preclinical evaluation of a 64Cu-labeled disintegrin for PET imaging of prostate cancer
摘要： A novel recombinant disintegrin, vicrostatin (VCN), displays high binding affinity to a broad range of human integrins in substantial competitive biological advantage over other integrin-based antagonists. In this study, we synthesized a new 64Cu-labeled VCN probe and evaluated its imaging properties for prostate cancer in PC-3 tumor-bearing mice. Macrocyclic chelating agent 1,8-diamino-3,6,10,13,16,19-hexaazabicyclo[6.6.6]-eicosine (DiAmSar) was conjugated with PEG unit and followed by coupling with VCN. The precursor was then radiolabeled with positron emitter 64Cu (t1/2 = 12.7 h) in ammonium acetate buffer to provide 64Cu-Sar-PEG-VCN, which was subsequently subjected to in vitro studies, small animal PET, and biodistribution studies. The PC-3 tumor-targeting efficacy of 64Cu-Sar-PEG-VCN was compared to a cyclic RGD peptide-based PET probe (64Cu-Sar-RGD). 64Cu labeling was achieved in 75% decay-corrected yield with radiochemical purity of > 98%. The specific activity of 64Cu-Sar-PEG-VCN was estimated to be 37 MBq/nmol. MicroPET imaging results showed that 64Cu-Sar-PEG-VCN has preferential tumor uptake and good tumor retention in PC-3 tumor xenografts. As compared to 64Cu-Sar-RGD, 64Cu-Sar-PEG-VCN produces higher tumor-to-muscle (T/M) imaging contrast ratios at 2 h (4.66 ± 0.34 vs. 2.88 ± 0.46) and 24 h (4.98 ± 0.80 vs. 3.22 ± 0.30) post-injection (pi) and similar tumor-to-liver ratios at 2 h (0.43 ± 0.09 vs. 0.37 ± 0.04) and 24 h (0.57 ± 0.13 vs. 0.52 ± 0.07) pi. The biodistribution results were consistent with the quantitative analysis of microPET imaging, demonstrating good T/M ratio (2.73 ± 0.36) of 64Cu-Sar-PEG-VCN at 48 h pi in PC-3 tumor xenografts. For both microPET and biodistribution studies at 48 h pi, the PC-3 tumor uptake of 64Cu-Sar-PEG-VCN is lower than that of 64Cu-Sar-RGD. 64Cu-Sar-PEG-VCN has the potential for in vivo imaging of prostate cancer with PET, which may provide a unique non-invasive method to quantitatively localize and characterize prostate cancer.
关键词： Angiogenesis,Disintegrin,PET imaging,Prostate cancer,64Cu,Vicrostatin
更新于2025-09-19 17:13:59
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Synthesis, radiolabelling and initial biological characterisation of <sup>18</sup> F-labelled xanthine derivatives for PET imaging of Eph receptors
摘要： Eph receptor tyrosine kinases, particularly EphA2 and EphB4, represent promising candidates for molecular imaging due to their essential role in cancer progression and therapy resistance. Xanthine derivatives were identified to be potent Eph receptor inhibitors with IC50 values in the low nanomolar range (1–40 nm). These compounds occupy the hydrophobic pocket of the ATP-binding site in the kinase domain. Based on lead compound 1, we designed two fluorine-18-labelled receptor tyrosine kinase inhibitors ([18F]2/3) as potential tracers for positron emission tomography (PET). Docking into the ATP-binding site allowed us to find the best position for radiolabelling. The replacement of the methyl group at the uracil residue ([18F]3) rather than the methyl group of the phenoxy moiety ([18F]2) by a fluoropropyl group was predicted to preserve the affinity of the lead compound 1. Herein, we point out a synthesis route to [18F]2 and [18F]3 and the respective tosylate precursors as well as a labelling procedure to insert fluorine-18. After radiolabelling, both radiotracers were obtained in approximately 5% radiochemical yield with high radiochemical purity (>98%) and a molar activity of >10 GBq μmol?1. In line with the docking studies, first cell experiments revealed specific, time-dependent binding and uptake of [18F]3 to EphA2 and EphB4-overexpressing A375 human melanoma cells, whereas [18F]2 did not accumulate at these cells. Since both tracers [18F]3 and [18F]2 are stable in rat blood, the novel radiotracers might be suitable for in vivo molecular imaging of Eph receptors with PET.
关键词： xanthine derivatives,molecular imaging,positron emission tomography (PET),fluorine-18-labelled,Eph receptor tyrosine kinases
更新于2025-09-19 17:13:59
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Radiology, Lasers, Nanoparticles and Prosthetics || 2. Nuclei and isotopes
摘要： In Chapters 5 to 12 nuclear methods in medicine are discussed either for imaging (scintigraphy, SPECT, PET) or for radiation treatment of cancerous tissues (proton and neutron irradiation, brachytherapy). It is therefore appropriate to first introduce some basic properties of nuclides and isotopes, and in particular of radioactive isotopes which are used in nuclear medicine. This chapter is not intended to replace a textbook on nuclear physics. But it provides sufficient background information for better understanding the subsequent chapters. Handling of radiation in general and application of radioactive isotopes also requires a detailed knowledge of radiation dose and radiation safety, which are topics of Chapter 4.
关键词： scintigraphy,medicine,SPECT,neutron irradiation,PET,brachytherapy,radiation safety,proton irradiation,nuclides,cancerous tissues,isotopes,radioactive isotopes,radiation dose,imaging,nuclear medicine,nuclear methods,radiation treatment
更新于2025-09-19 17:13:59
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Novel fluorescently labelled ATP analogues for direct monitoring of ubiquitin activation
摘要： Simple and robust assays to monitor enzymatic ATP cleavage with high efficiency in real-time are scarce. To address this shortcoming, we developed novel fluorescently labelled adenosine tri-, tetra- and pentaphosphate analogues of ATP. The novel ATP analogues bear – in contrast to earlier reports – only a single acridone-based dye at the terminal phosphate group. The dye’s fluorescence is quenched by the adenine component of the ATP analogue and is restored upon cleavage of the phosphate chain and dissociation of the dye from the adenosine moiety. Thereby the activity of ATP cleaving enzymes can be followed in real-time. We demonstrate this proficiency for ubiquitin activation by the ubiquitin-activating enzymes UBA1 and UBA6 which represents the first step in an enzymatic cascade leading to the covalent attachment of ubiquitin to substrate proteins, a process that is highly conserved from yeast to humans. We found that the efficiency to serve as cofactor for UBA1/UBA6 very much depends on the length of the phosphate chain of the ATP analogue: triphosphates are used poorly while pentaphosphates are most efficiently processed. Notably, the novel pentaphosphate-harbouring ATP analogue supersedes the efficiency of recently reported dual-dye labelled analogues and thus, is a promising candidate for broad applications.
关键词： ubiquitin,fluorescent probes,PET,UBA1,ATP
更新于2025-09-19 17:13:59
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Experimental investigation on nuclear reactions using a laser-accelerated proton and deuteron beam
摘要： We report an experimental investigation on nuclear reactions using an intense, ultra-short laser-accelerated proton and deuteron beam generated by the interaction of 25 fs, 150 TW Ti: sapphire laser pulse with normal thin foils and foils containing deuterium atoms. The production of a positron-emitting short-lived 11C radio-isotope from the interaction of protons and deuterium ions with a solid boron palette by means of 11B (p, n)11C and 10B (d, n)11C nuclear reactions was studied. The maximum radioactivity in the optimized laser irradiation condition was found to be 5.2 kBq per laser shot, which corresponds to ～9 × 106 atoms of 11C isotopes using the 11B (p, n)11C reaction. The relative ef?ciency of 11C production using a proton and deuteron beam was also explored experimentally. About 30 % enhancement in 11C activity was observed with CD2 coated targets. It was also found that because of the relatively low deuteron energy threshold of the reaction 10B (d, n)11C, even the low energy part of the accelerated deuterons in the spectrum can be used for ef?cient 11C production. In the same setup, the proton-induced fusion reaction in the boron target (p + 5B11 ? 3α + 8.7 MeV) was also studied. The resultant fusion yield and alpha particle energy spectrum was measured.
关键词： p?11B fusion,laser particle acceleration,positron emission tomography (PET) isotopes,laser driven ion acceleration,laser plasma interaction,laser induced nuclear reactions,high intensity lasers
更新于2025-09-19 17:13:59
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Laser-Assisted Fabrication of a Highly Sensitive and Flexible Micro Pyramid-Structured Pressure Sensor for E-Skin Applications
摘要： A novel capacitive pressure sensor based on micro-structured polydimethylsiloxane (PDMS) dielectric layer was developed for wearable E-skin and touch sensing applications. The pressure sensor was fabricated on a flexible polyethylene terephthalate (PET) substrate, using PDMS and silver (Ag) as the dielectric and electrode layers, respectively. A set of PDMS films with pyramid shaped micro-structures were fabricated using a laser engraved acrylic mold. The electrodes (top and bottom) were fabricated by depositing Ag on PET films using additive screen-printing process. The pressure sensor was assembled by attaching the top and bottom Ag electrodes to the smooth side of pyramid shaped micro-structured PDMS (PM-PDMS) films. The top PM-PDMS was then placed on the bottom PM-PDMS. The capability of the fabricated pressure sensor was investigated by subjecting the sensor to pressures ranging from 0 to 10 kPa. A sensitivity of 0.221% Pa-1, 0.033% Pa-1 and 0.011% Pa-1 along with a correlation coefficient of 0.9536, 0.9586 and 0.9826 was obtained for the pressure sensor in the pressure range of 0 Pa to 100 Pa, 100 Pa to 1000 Pa, and 1 kPa to 10 kPa, respectively. The pressure sensor also possesses a fast response time of 50 ms, low hysteresis of 0.7%, recovery time of 150 ms and excellent cycling stability over 1000 cycles. The results demonstrated the efficient detection of pressure generated from various activities such as hand gesture and carotid pulse measurement. The PM-PDMS based pressure sensor offers a simple and cost-effective approach to monitor pressure in E-skin applications.
关键词： E-skin,Laser patterning,Pressure sensor,Micro-pyramid structure,Polydimethylsiloxane (PDMS),Screen printing process,Polyethylene terephthalate (PET)
更新于2025-09-19 17:13:59