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1.
Talanta ; 206: 120207, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514857

RESUMO

Herein, a multicommuted flow-batch setup and a photometric procedure for the determination of mercury at the ppb level in aqueous samples are described. The setup was designed to implement a versatile solvent extraction and pre-concentration strategy by combining flow-batch and multicommuted flow analysis approaches. The photometric method was based on Hg(II) reaction with dithizone in a chloroform medium, which was also used as the extracting organic solvent. The flow analysis system was composed of a homemade syringe pump module, a set of solenoid valves, two Aquarius mini-pumps, and a flow-batch chamber. The homemade photometer was comprised of a light emitting diode (LED), photodiode, and homemade flow cell (50 mm length). The flow system and photometer were controlled using an Arduino Due board, running custom-written software. After optimizing the operational conditions, the effectiveness of the developed system was evaluated for the determination of the mercury concentration in drinking water. For accuracy assessment, samples were analyzed using a spiking methodology and an independent method, yielding a recovery ranging from 92% to 108%. Other important characteristics of the proposed method were found as follows: linear response range, 0.5-10.0 µg L-1 (r = 0.9984); limit of detection 0.38 µg L-1 Hg(II); consumption of dithizone and chloroform, 1.85 µg L-1 and 0.8 mL per analysis, respectively; coefficient of variation, 2% (n = 10); sampling throughput, 20 determinations per h.


Assuntos
Água Potável/análise , Mercúrio/análise , Fotometria/métodos , Poluentes Químicos da Água/análise , Clorofórmio/química , Ditizona/química , Química Verde/instrumentação , Química Verde/métodos , Limite de Detecção , Águas Minerais/análise , Fotometria/instrumentação , Rios/química
2.
Talanta ; 204: 586-591, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31357338

RESUMO

A simple, small and inexpensive photometer that uses a pair of light-emitting diodes (LEDs) and a simple operational amplifier was developed for investigating thiocyanate levels in saliva obtained from smokers and non-smokers. The photometer is based on paired emitter-detector diodes (PEDDs), and the entire system can be purchased for less than a hundred US dollars. The PEDD-based photometer can measure the transmittance of a solution in a 1-cm disposable polystyrene cuvette using only rechargeable dry-cell batteries, which makes it suitable for analysis outside of equipped laboratories. The metal complex formation between Fe (III) and thiocyanate ions in an acidic condition permits colorimetric detection of thiocyanate ions using LEDs emitting at 465 nm, because the complex shows maximum absorption at 457 nm. The developed photometer exhibits excellent performance with linearity ranging from 0.05 mmol L-1 to 0.75 mmol L-1 and a correlation coefficient (r2) > 0.999. The limits of detection and quantification were 0.01 mmol L-1 and 0.05 mmol L-1, respectively. Both intra- and inter-day precision were obtained with relative standard deviations (RSD) of less than 1% in the determination of thiocyanate. The proposed method is simple, facile, and sensitive enough to investigate the levels of thiocyanate in the saliva samples of smokers and non-smokers with centrifugation being the only special treatment for samples. The results showed that the concentrations of thiocyanate were approximately 5-fold higher in smokers than in non-smokers.


Assuntos
Saliva/química , Tiocianatos/análise , Colorimetria/instrumentação , Colorimetria/métodos , Humanos , Ferro/análise , Iluminação/instrumentação , Limite de Detecção , não Fumantes , Fotometria/instrumentação , Fotometria/métodos , Reprodutibilidade dos Testes , Fumantes
3.
Neurosci Bull ; 35(3): 425-433, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31062336

RESUMO

Fiber photometry is a sensitive and easy way to detect changes in fluorescent signals. The combination of fiber photometry with various fluorescent biomarkers has substantially advanced neuroscience research over the last decade. Despite the wide use of fiber photometry in biomedical fields, the lack of a detailed and comprehensive protocol has limited progress and sometimes complicated the interpretation of data. Here, we describe detailed procedures of fiber photometry for the long-term monitoring of neuronal activity in freely-behaving animals, including surgery, apparatus setup, data collection, and analysis.


Assuntos
Encéfalo/metabolismo , Sinalização do Cálcio , Neurônios/metabolismo , Imagem Óptica/métodos , Fotometria/métodos , Animais , Feminino , Masculino , Camundongos , Procedimentos Neurocirúrgicos , Fibras Ópticas , Imagem Óptica/instrumentação , Fotometria/instrumentação
4.
Appl Spectrosc ; 73(1): 104-114, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30012006

RESUMO

The use of rotating filter wheels is common in photometric applications. Traditional filter wheel designs typically exhibit a number of filter openings spaced evenly about the circumference of the wheel. In this work we examine a number of shortcomings of this traditional filter design in measurements of phytoplankton fluorescence made with our fluorescence imaging photometer (FIP). We present an alternative asymmetric wheel design that offers a number of advantages over the traditional design as well as a new processing algorithm designed to accommodate convolution of signals from adjacent channels inherent in measurements collected with the asymmetric design. This approach eliminates the need for a separate signal to establish timing and wheel position, unambiguously establishes filter order even when the direction of rotation is unknown, allows for better estimates of signal baseline, and is more resilient to effects of vibration and other dynamic processes that could occur on the time scale of wheel rotation. We demonstrate performance improvements for phytoplankton fluorescence measurements associated with the new wheel design and algorithm compared with previously published methods using the FIP. Both the improved image processing algorithm and filter wheel design were found to reduce noise in our measurements significantly.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador/métodos , Imagem Óptica/métodos , Fitoplâncton , Desenho de Equipamento , Microscopia de Fluorescência/instrumentação , Microscopia de Fluorescência/métodos , Imagem Óptica/instrumentação , Fotometria/instrumentação , Fotometria/métodos , Fitoplâncton/química , Fitoplâncton/citologia
6.
Sensors (Basel) ; 18(12)2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30469476

RESUMO

Despite its broad penetration of various markets, the quantitative lateral flow immunoassay (LFIA) suffers from sensitivity issues in some cases. To solve this problem, an optimized colorimetric readout method for LFIA quantification is proposed in this study. An assay reader device utilizing a color camera and an analysis method using a Bayer filtered image were developed. Spectrometric measurements of the assay test line were performed to determine the color channel that contains the test line information and effectively minimizes noise. The change in the intensity ratio with increasing concentration of the target substance in the sample was largest in the green channel. The linear range of the output curve ranged from 0 to 10 ng/mL, and the detection limit was 2 ng/mL. The suggested instrumentation and analysis methods are expected to effectively resolve the low-sensitivity problems of the former LFIA systems and to offer other prospective functionalities for LFIA quantification.


Assuntos
Técnicas Biossensoriais/instrumentação , Colorimetria/instrumentação , Imunoensaio/instrumentação , Fotometria/instrumentação , Cor , Coleta de Dados , Limite de Detecção , Fenômenos Físicos
7.
J Environ Sci (China) ; 74: 50-57, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30340674

RESUMO

Aerosol plays a key role in determining radiative balance, regional climate and human health. Severe air pollution over Northeast China in recent years urges more comprehensive studies to figure out the adverse effects caused by excessive aerosols. In this study, column aerosol measurements over urban Harbin, a metropolis located at the highest latitude in Northeast China, during May 2016 to March 2017 were conducted using a CIMEL sun-photometer to analyze local aerosol properties and its variation from different aspects. According to the observations, aerosol optical depth at 440nm (AOD440) ranges from 0.07 up to 1.54, and the large variability in both AOD440 and Angstrom Exponent (AE440-870) indicates the frequent change of aerosol types due of different emission sources. Coarse mode particles dominated Harbin during the studying period because of the long-range transported dust and probably the suspended snow crystals in winter. As the wavelength increases, relatively consistent decrease trends of single scattering albedo (SSA) and asymmetry factor (ASY) were observed in spring, autumn, and winter, indicating the presence of absorbing polluted aerosols. Mixed type (MIX) aerosol dominated the study region with a total percentage of 34%, and biomass burning and urban industry (BB/UI), clean continental (CC), and desert dust (DD) aerosols were found to be 31%, 27%, and 8%, respectively. The current work fills up the optical characteristics of aerosols in Harbin, and will contribute to the in-depth understanding of local aerosol variation and regional climate change over Northeast China.


Assuntos
Poluentes Atmosféricos/análise , Cidades , Monitoramento Ambiental , Fenômenos Ópticos , Fotometria/instrumentação , Luz Solar , Aerossóis , China
8.
Anal Chim Acta ; 1032: 197-202, 2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30143218

RESUMO

A new high sensitivity deep-UV LED photometric detector with a z-type flow cell (45 nL or 180 nL) for miniaturised and portable capillary liquid chromatography (LC) was designed and fabricated to overcome sensitivity limitations due to short pathlength in on-capillary detectors. The new detector has a 10 mm geometric pathlength and uses high intensity light-emitting diodes (LED) as light sources in the deep-UV range (254 nm and 280 nm). No optical reference was necessary due to the low drift in the signal. Stray light was minimized by the use of an adjustable slit with a 0.5 mm pinhole. The direct relationship between absorbance and concentration was obtained using dichromate to evaluate the sensitivity and the linearity range of the detector. Performance of the miniaturised version was compared with that obtained from a commercial benchtop detector for capillary LC under the same conditions using the same optical z-cell. The miniaturised version exhibited a superior performance across all parameters, including 3 times higher effective pathlength, 4 times higher upper limit of detector linearity, and 2-5 times lower stray light levels. An application of the new detector was shown with the detection of l-dopa, l-tyrosine, norfenefrine, phenylephrine and tyramine, separated using capillary LC. The baseline noise level recorded was as low as 3.9 µAU. Further, the detector was applied in a miniaturised capillary LC for the indirect detection of common inorganic anions. In comparison to an on-capillary LED detector applied under similar chromatographic conditions, there was a 50 times higher signal to noise (S/N) ratio.


Assuntos
Levodopa/análise , Octopamina/análogos & derivados , Fenilefrina/análise , Fotometria , Tiramina/análise , Tirosina/análise , Cromatografia Líquida/instrumentação , Octopamina/análise , Fotometria/instrumentação , Raios Ultravioleta
9.
IEEE Trans Biomed Circuits Syst ; 12(3): 495-509, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29877814

RESUMO

Fluorescence biophotometry measurements require wide dynamic range (DR) and high-sensitivity laboratory apparatus. Indeed, it is often very challenging to accurately resolve the small fluorescence variations in presence of noise and high-background tissue autofluorescence. There is a great need for smaller detectors combining high linearity, high sensitivity, and high-energy efficiency. This paper presents a new biophotometry sensor merging two individual building blocks, namely a low-noise sensing front-end and a order continuous-time modulator (CTSDM), into a single module for enabling high-sensitivity and high energy-efficiency photo-sensing. In particular, a differential CMOS photodetector associated with a differential capacitive transimpedance amplifier-based sensing front-end is merged with an incremental order 1-bit CTSDM to achieve a large DR, low hardware complexity, and high-energy efficiency. The sensor leverages a hardware sharing strategy to simplify the implementation and reduce power consumption. The proposed CMOS biosensor is integrated within a miniature wireless head mountable prototype for enabling biophotometry with a single implantable fiber in the brain of live mice. The proposed biophotometry sensor is implemented in a 0.18- CMOS technology, consuming from a 1.8- supply voltage, while achieving a peak dynamic range of over a 50- input bandwidth, a sensitivity of 24 mV/nW, and a minimum detectable current of 2.46- at a 20- sampling rate.


Assuntos
Técnicas Biossensoriais , Fotometria , Tecnologia sem Fio/instrumentação , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Humanos , Fotometria/instrumentação , Fotometria/métodos
10.
J Immunol Methods ; 459: 44-49, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29802878

RESUMO

Multiplex assays for autoantibodies have shown utility both in research towards understanding the basic biology of autoimmune disease, and as tools for clinical diagnosis. New label-free multiplex analysis methods have the potential to streamline both the process of assay development and assay workflow. We report fabrication and testing of a 5-plex autoantigen microarray using the Arrayed Imaging Reflectometry (AIR) platform. This label-free technology provides rapid, sensitive, and quantitative detection of an arbitrary number of analytes in a standard multiwell format. In this work, we demonstrate that AIR is able to detect antibodies to Ro60, La/SSB, Scl-70, BicD2, and Ro52 in single-donor human serum samples with multiplex results comparable to singleplex ELISA or Luminex assays.


Assuntos
Autoanticorpos/sangue , Autoantígenos/imunologia , Doenças Autoimunes/diagnóstico , Técnicas Biossensoriais/métodos , Análise Serial de Proteínas/métodos , Autoantígenos/sangue , Doenças Autoimunes/sangue , Técnicas Biossensoriais/instrumentação , Ensaio de Imunoadsorção Enzimática , Humanos , Fotometria/instrumentação , Análise Serial de Proteínas/instrumentação
11.
Jpn J Ophthalmol ; 62(4): 473-480, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29594609

RESUMO

PURPOSE: The macular pigment optical density (MPOD) of a Japanese population was measured using a commercially based heterochromatic flicker photometer, the Macular Pigment Screener (MPS2). The objective of the study was to evaluate the accuracy and test-retest reliability of the MPS2 in Asian pigmented eyes. STUDY DESIGN: Experimental study to validate the medical instrument in humans. METHODS: Twenty-four healthy Japanese participants with no systemic or eye diseases (men: 13, women: 11; mean [SD] age 38.6 [10.9 years]) were included. The concordance of the MPOD, obtained using the MPS2 and Macular Metrics II (MM2), and the test-retest reliability were examined. RESULTS: Determination of the MPOD was unsuccessful in 1 participant; thus, the MPOD of 23 participants was analyzed. The mean (SD) MPOD measured with the detail-mode of the MPS2 was 0.63 (0.18) and with that of the MM2, it was 0.72 (0.23). The former was significantly lower than the latter (P = .003, paired t test). The MPOD measured with the MPS2 and the MM2 showed good concordance (r = 0.79, P < .001, Pearson product moment correlation). Bland-Altman analyses showed no systematic errors between the MPS2 and the MM2. The intraclass correlation coefficient over 5 measurement times with the detail-mode of the MPS2 was 0.80, and the mean coefficient of variation was 9.4%. CONCLUSION: The high concordance with the MM2 and good test-retest reliability found by this study suggest that the MPS2 is acceptable for use in a Japanese population. However, the mean MPOD yielded by the MPS2 was significantly lower than that yielded by the MM2. Therefore, the MPS2 and MM2 are not interchangeable in a single study.


Assuntos
Macula Lutea/diagnóstico por imagem , Pigmento Macular/análise , Fotometria/instrumentação , Adulto , Desenho de Equipamento , Feminino , Voluntários Saudáveis , Humanos , Japão , Masculino , Reprodutibilidade dos Testes
12.
Anal Chem ; 90(4): 2564-2569, 2018 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-29378413

RESUMO

This paper presents a novel hand-held photometer, termed "Photopette", for on-spot absorbance measurements of biochemical analytes. The Photopette is a multicomponent, highly portable device with an overall weight of 160 g, which fits within 202 mm × 47 mm × 42 mm. Designed in the form factor of a micropipette, Photopette integrates a photodiode detector with light emitting diodes (LEDs) to form a highly customizable photometer which supports a wide variety of applications within the wavelengths between 260 and 1050 nm. A dual-purpose disposable reflective tip was designed to act as a sample holder and a light-reflecting system, which is in stark contrast to the operation of mainstream spectrophotometers and photometers. Small volume analytes may be measured with low sample loss using this proprietary CuveTip. A user-friendly software application running on smart devices was developed to control and read the values from Photopette via a low-energy Bluetooth link. This one-step strategy allows measurements on-spot without sample transfer, minimizing cross-contamination and human error. The results reported in this paper demonstrate Photopette's great potential to quantify DNA, direct protein, and cell density directly within the laminar flow hood. Results are compared with a Nanodrop 2000c spectrophotometer, a mainstream spectrophotometer for small-volume measurements.


Assuntos
DNA/análise , Fotometria , Proteínas/análise , Contagem de Células , Células HeLa , Humanos , Fotometria/instrumentação , Células Tumorais Cultivadas
13.
Anal Bioanal Chem ; 410(3): 695-713, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29032457

RESUMO

MicroRNAs (miRNAs) are single-stranded noncoding RNA molecules that act as key regulators of mRNA expression and are emerging biomarkers for disease. Their small size (18-25 nt) presents challenges to molecular recognition, labeling, and signal generation. Recent research activity in this field has aimed at the development of methods for miRNA quantification that combine high detectability, broad dynamic range, practicality, multiplexity, and low cost for prospective applications in diagnostic laboratories. This review article covers the most recent advances in microRNA analysis.


Assuntos
Técnicas de Química Analítica/métodos , MicroRNAs/análise , Animais , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Técnicas de Química Analítica/instrumentação , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Desenho de Equipamento , Fluorometria/instrumentação , Fluorometria/métodos , Humanos , Medições Luminescentes/instrumentação , Medições Luminescentes/métodos , Espectrometria de Massas/instrumentação , Espectrometria de Massas/métodos , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos , Hibridização de Ácido Nucleico/métodos , Fotometria/instrumentação , Fotometria/métodos , Técnicas de Microbalança de Cristal de Quartzo/instrumentação , Técnicas de Microbalança de Cristal de Quartzo/métodos , Análise Espectral Raman/instrumentação , Análise Espectral Raman/métodos
14.
Fed Regist ; 82(242): 60306-8, 2017 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-29260838

RESUMO

The Food and Drug Administration (FDA or we) is classifying the image processing device for estimation of external blood loss into class II (special controls). The special controls that apply to the device type are identified in this order and will be part of the codified language for the image processing device for estimation of external blood loss' classification. We are taking this action because we have determined that classifying the device into class II (special controls) will provide a reasonable assurance of safety and effectiveness of the device. We believe this action will also enhance patients' access to beneficial innovative devices, in part by reducing regulatory burdens.


Assuntos
Segurança de Equipamentos/classificação , Processamento de Imagem Assistida por Computador/classificação , Processamento de Imagem Assistida por Computador/instrumentação , Fotometria/classificação , Fotometria/instrumentação , Perda Sanguínea Cirúrgica , Hemoglobinas , Humanos , Tampões de Gaze Cirúrgicos
15.
Appl Opt ; 56(30): 8520-8526, 2017 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-29091634

RESUMO

In this paper, an analytical basis of ray tracing for optical biometry of media by ellipsoidal reflectors was developed. A ray-tracing algorithm was created, which involves determining the point of interaction of the incident beam with the ellipsoidal reflector, calculating the direction of the reflected beam, and determining the intersection point of the reflected ray with the second ellipsoid focal plane, taking into account the statistical weight of photons. For imaging in the optical biometry of media by ellipsoidal reflectors, the results of a real experiment and a Monte Carlo simulation for chicken muscle tissue samples of different thicknesses for the wavelength of 632.8 nm are used.


Assuntos
Algoritmos , Biometria , Músculo Esquelético , Fotometria/métodos , Espalhamento de Radiação , Animais , Galinhas , Método de Monte Carlo , Fotometria/instrumentação , Fótons
16.
Arch. Soc. Esp. Oftalmol ; 92(11): 516-520, nov. 2017. tab
Artigo em Espanhol | IBECS | ID: ibc-167810

RESUMO

Objetivo: La finalidad de este trabajo fue determinar la difusión de la luz en pacientes con distrofia endotelial de Fuchs sin edema corneal clínicamente significativo, y evaluar su relación con el recuento de células endoteliales, paquimetría y parámetros biomecánicos corneales. Materiales y métodos: Los valores de difusión de la luz fueron medidos usando el C-Quant(R) (Oculus Optikgeräte GmbH, Alemania) en 32 ojos de 17 pacientes diagnosticados de distrofia endotelial de Fuchs sin edema corneal clínicamente significativo. Las propiedades biomecánicas corneales fueron determinadas usando ORA y Corvis ST(R). Resultados: El 93,8% de los ojos estudiados mostraron un valor de difusión de la luz fuera del rango normal. No se encontró ninguna correlación estadísticamente significativa (p > 0,05) entre los valores de difusión de la luz medidos mediante el C-Quant(R) y el recuento endotelial, la paquimetría o las propiedades biomecánicas corneales. Conclusiones: En nuestro estudio encontramos una alteración en los valores de difusión de la luz de los pacientes con distrofia endotelial de Fuchs. Esta alteración no parece correlacionarse significativamente con la gravedad de la enfermedad (AU)


Objective: The purpose of this study was to determine the light scattering in patients with Fuchs' endothelial dystrophy without clinically significant corneal oedema, and evaluate its relationship with endothelial cell count, corneal thickness, and corneal biomechanical parameters. Materials and methods: The values of light scattering were measured by C-Quant(R) (Oculus Optikgeräte GmbH, Germany) in 32 eyes of 17 patients diagnosed with Fuchs' endothelial dystrophy without clinically significant corneal oedema. Corneal biomechanical properties were determined using ORA (ocular response) and Corvis ST(R) (tonometry). Results: A light scattering value outside the normal range was observed in 93.8% of eyes studied. No statistically significant association (P>.05) was found between the values of the measured light scattering by C-Quant(R) and endothelial count, pachymetry, or corneal biomechanical properties. Conclusions: In this study, changes were found in the values of light scattering values of patients with corneal Fuchs' endothelial dystrophy. This change does not appear to correlate significantly with disease severity (AU)


Assuntos
Humanos , Distrofia Endotelial de Fuchs/fisiopatologia , Fotometria/instrumentação , Córnea/fisiologia , Células Endoteliais/fisiologia , Paquimetria Corneana , Fenômenos Biomecânicos
17.
Sci Rep ; 7(1): 11384, 2017 09 12.
Artigo em Inglês | MEDLINE | ID: mdl-28900174

RESUMO

A broadband photodetector has been developed on the basis of ZnO nanowires (NWs)/Rhodamine B (RhB) hybrid system. The device is fabricated by spraying NWs on to gold interdigital electrodes followed by modifying the NWs via an RhB solution-casting process. Measurements show that the as-fabricated device demonstrates photoresponsivity ranging from 300 nm to 700 nm with a bandwidth as large as 400 nm. The role of the dye sensitizer adsorbed on the surface of NWs is modeled to alter the transportation path of photo-generated carriers. The calculations based on the measurements reveal that the device exhibits a prominent responsivity in the interested band with maximum responsivity of 5.5 A/W for ultraviolet (UV) light and 3 A/W for visible (VIS) light under 8 V bias, respectively. The sensitization not only widens the response spectrum with external quantum efficiency leaping up to 771% at VIS but also improves UV responsivity with maximum 51% enhancement. From the time-dependent photo-current measurement, it is found that the response time (rise and decay times in total) of the device largely reduced from 17.5 s to 3.3 s after sensitization. A comparison of the obtained photodetector with other ZnO-based photodetectors is summarized from the view point of responsivity and bandwidth.


Assuntos
Nanofios , Fotometria/métodos , Rodaminas , Óxido de Zinco , Nanofios/química , Nanofios/ultraestrutura , Fotometria/instrumentação , Rodaminas/química , Análise Espectral , Óxido de Zinco/química
18.
Radiology ; 285(3): 980-989, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28753389

RESUMO

Purpose To investigate whether photon-counting detector (PCD) technology can improve dose-reduced chest computed tomography (CT) image quality compared with that attained with conventional energy-integrating detector (EID) technology in vivo. Materials and Methods This was a HIPAA-compliant institutional review board-approved study, with informed consent from patients. Dose-reduced spiral unenhanced lung EID and PCD CT examinations were performed in 30 asymptomatic volunteers in accordance with manufacturer-recommended guidelines for CT lung cancer screening (120-kVp tube voltage, 20-mAs reference tube current-time product for both detectors). Quantitative analysis of images included measurement of mean attenuation, noise power spectrum (NPS), and lung nodule contrast-to-noise ratio (CNR). Images were qualitatively analyzed by three radiologists blinded to detector type. Reproducibility was assessed with the intraclass correlation coefficient (ICC). McNemar, paired t, and Wilcoxon signed-rank tests were used to compare image quality. Results Thirty study subjects were evaluated (mean age, 55.0 years ± 8.7 [standard deviation]; 14 men). Of these patients, 10 had a normal body mass index (BMI) (BMI range, 18.5-24.9 kg/m2; group 1), 10 were overweight (BMI range, 25.0-29.9 kg/m2; group 2), and 10 were obese (BMI ≥30.0 kg/m2, group 3). PCD diagnostic quality was higher than EID diagnostic quality (P = .016, P = .016, and P = .013 for readers 1, 2, and 3, respectively), with significantly better NPS and image quality scores for lung, soft tissue, and bone and with fewer beam-hardening artifacts (all P < .001). Image noise was significantly lower for PCD images in all BMI groups (P < .001 for groups 1 and 3, P < .01 for group 2), with higher CNR for lung nodule detection (12.1 ± 1.7 vs 10.0 ± 1.8, P < .001). Inter- and intrareader reproducibility were good (all ICC > 0.800). Conclusion Initial human experience with dose-reduced PCD chest CT demonstrated lower image noise compared with conventional EID CT, with better diagnostic quality and lung nodule CNR. © RSNA, 2017 Online supplemental material is available for this article.


Assuntos
Fotometria/instrumentação , Exposição à Radiação/prevenção & controle , Proteção Radiológica/instrumentação , Radiografia Torácica/instrumentação , Tomografia Computadorizada por Raios X/instrumentação , Idoso , Desenho de Equipamento , Análise de Falha de Equipamento , Estudos de Viabilidade , Humanos , Pessoa de Meia-Idade , Fotometria/métodos , Projetos Piloto , Doses de Radiação , Proteção Radiológica/métodos , Radiografia Torácica/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X/métodos
19.
J Appl Clin Med Phys ; 18(2): 170-175, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28300388

RESUMO

The purpose of this work was to perform the initial evaluation of primary diagnostic monitor (PDM) characteristics following the implementation of New York City quality assurance (NYC QA) regulations on January 1, 2016, and compare the results of the QA measurements performed by an external photometer and the PDM manufacturer's built-in photometer. TG-18 and Society of Motion Picture and Television Engineers test patterns were used to evaluate monitor performance. Overall, 79 PDMs were included in the analysis. The verification of grayscale standard display function (GSDF) calibration, using a built-in photometer, showed that only 2 out of 79 PDMs failed calibration. However, the same measurements performed by the external luminance meter showed that 15 out of 79 monitors had failed GSDF calibration. Measurements of the PDMs maximum luminance (Lmax ), using an external photometer showed that 10 out of 53 PDMs calibrated for Lmax = 400 cd/m2 and 17 out of 26 PDMs calibrated for Lmax = 500 cd/m2 do not meet the manufacturer's recommended 10% tolerance limit for the target Lmax calibration. Two PDMs did not pass the Lmax ≥ 350 cd/m2 NYC QA regulations with Lmax = 331 cd/m2 and Lmax = 340 cd/m2 . All tested PDMs exceeded the minimum luminance ratio (LR) of 250:1 as required by NYC QA regulations. Measurements taken of Lmax and LR performed by a built-in photometer showed that none of the PDMs had failed the NYC QA regulations. All PDMs passed the luminance uniformity test with a maximum nonuniformity of 17% (according to NYC regulations it must be less than 30%). The luminance uniformity test could only be performed using an external photometer. The evaluation of 79 PDMs of various ages and models demonstrated up to 18% disagreement between luminance measurements performed by the manufacturer's built-in photometer when compared with those performed by an externally calibrated luminance meter. These disagreements were larger for older PDMs.


Assuntos
Diagnóstico por Imagem/instrumentação , Processamento de Imagem Assistida por Computador/métodos , Fotometria/instrumentação , Garantia da Qualidade dos Cuidados de Saúde/normas , Calibragem , Humanos , Medições Luminescentes , Padrões de Referência
20.
J Mol Microbiol Biotechnol ; 27(2): 73-80, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28171869

RESUMO

To more efficiently process the large sample numbers for quantitative determination of ammonium (NH4+) and phosphate (orthophosphate, PO43-) generated during comprehensive growth experiments with the marine Roseobacter group member Phaeobacter inhibens DSM 17395, specific colorimetric assays employing a microplate reader (MPR) were established. The NH4+ assay is based on the reaction of NH4+ with hypochlorite and salicylate, yielding a limit of detection of 14 µM, a limit of quantitation of 36 µM, and a linear range for quantitative determination up to 200 µM. The PO43-assay is based on the complex formation of PO43- with ammonium molybdate in the presence of ascorbate and zinc acetate, yielding a limit of detection of 13 µM, a limit of quantitation of 50 µM, and a linear range for quantitative determination up to 1 mM. Both MPR-based assays allowed for fast (significantly lower than 1 h) analysis of 21 samples plus standards for calibration (all measured in triplicates) and showed only low variation across a large collection of biological samples.


Assuntos
Compostos de Amônio/análise , Meios de Cultura/química , Fosfatos/análise , Fotometria/métodos , Água do Mar/química , Compostos de Amônio/química , Ácido Ascórbico/química , Ácido Hipocloroso/química , Molibdênio/química , Fosfatos/química , Fotometria/instrumentação , Roseobacter/crescimento & desenvolvimento , Roseobacter/metabolismo , Salicilatos/química , Sensibilidade e Especificidade , Estatística como Assunto , Acetato de Zinco/química
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