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1.
Zhongguo Zhong Yao Za Zhi ; 45(22): 5511-5517, 2020 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-33350213

RESUMO

Evaporative light scattering detector(ELSD) and charged aerosol detector(CAD) methods were established in this study for the content determination of four kinds of sugars in Zhusheyong Yiqi Fumai(YQFM), and the factors affecting the accuracy of CAD methods were discussed. HPLC-ELSD chromatographic separation was performed on a Shodex Asahipak NH2 P-50 column with acetonitrile-water(75∶25)as the mobile phase, with a flow rate of 0.8 mL·min~(-1), drift tube temperature of 80 ℃. The analysis by HPLC-CAD was performed on the same column with acetonitrile-water as mobile phase for gradient elution, with a flow rate of 0.8 mL·min~(-1), a neb temperature of 45 ℃, and power function(PF) of 1.3. The samples of YQFM were detected by ELSD and CAD respectively. It was found that YQFM was composed of fructose, glucose, sucrose and maltose. The linear relationship of the two methods was good, and the recoveries, reproducibility and stability of these four kinds of sugars measured by the two methods satisfied the requirements of methodology. Both CAD and ELSD detectors were accurate and reliable in detecting saccharides components in YQFM. In addition, it was revealed in this study for the first time that the PF parameter of CAD had an important influence on the accuracy of sugar determination and acted as the key parameter of CAD method. It was also found that for CAD, a non-linear detector, there was no significant difference between the results of linear regression and logarithmic regression.


Assuntos
Carboidratos , Açúcares , Aerossóis , Cromatografia Líquida de Alta Pressão , Luz , Reprodutibilidade dos Testes , Espalhamento de Radiação
2.
Nan Fang Yi Ke Da Xue Xue Bao ; 40(6): 843-849, 2020 Jun 30.
Artigo em Chinês | MEDLINE | ID: mdl-32895202

RESUMO

OBJECTIVE: To develop a fast, sensitive and cost-effective method based on resonance light scattering (RLS) for characterization of protein solubility to facilitate detection of changes in solubility of mutant proteins. METHODS: We examined the response curve of RLS intensities to the protein concentrations in synchronous scanning mode. The curve intersection points were searched to predict the maximal concentrations of the protein in dispersion state, which defined the solubility of the protein in this given state. Bovine serum albumin (BSA, 0-50 g/L) was used as the model to investigate the influences of pH values (6.5, 7.0, and 7.4) and salt concentrations (0.05, 0.10, 0.15, and 0.20 mol/L) on the determined solubility. The solubility of glutathione S-transferase isoenzymes alpha (GSTA, 0-27.0 g/L) and Mµ (GSTM, 0-20.0 g/L) were estimated for comparison. The RLS-based method was used to determine the solubility of uricase (MGU, 0-0.4 g/L) to provide assistance in improving the solubility of its mutants. RESULTS: We identified two intersection points in the RLS response curves of the tested proteins, among which the lower one represented an approximation of the maximal concentration (or the solubility of the protein) in single molecular dispersion, and the higher one the saturated concentration of the protein in multiple molecular aggregation. In HEPES buffer, the two intersection points of BSA (isoelectric point 4.6) both increased with the increase of pH (6.5-7.4), and their values were ~1.2 g/L and ~33 g/L at pH 7.4, respectively; the latter concentration approached the solubility of commercial BSA in the same buffer at the same pH. The addition of NaCl reduced the values of the two intersection points, and increasing salt ion concentration decreased the values of the lower intersection points. Further characterizations of GSTA and GSTM showed that the low concentration intersection points of the two proteins were ~0.7 g/L and ~0.8 g/L, and their high concentration intersection points were ~10 g/L and ~11 g/L, respectively, both lower than those of BSA, indicating the feasibility of the direct characterization of protein solubility by RLS. The two concentration intersection points of MGU were 0.24 g/L and 0.30 g/L, respectively, and the low concentration intersection point of its selected mutant was increased by 2 times. CONCLUSIONS: RLS allows direct characterization of the solubility of macromolecular proteins. This method, which is simple and sensitive and needs only a small amount of proteins, has a unique advantage for rapid comparison of solubility of low-abundance protein mutants.


Assuntos
Luz , Concentração de Íons de Hidrogênio , Espalhamento de Radiação , Solubilidade , Análise Espectral
3.
Nat Protoc ; 15(9): 2773-2784, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32737465

RESUMO

Spherical aberration (SA) occurs when light rays entering at different points of a spherical lens are not focused to the same point of the optical axis. SA that occurs inside the lens elements of a fluorescence microscope is well understood and corrected for. However, SA is also induced when light passes through an interface of refractive index (RI)-mismatched substances (i.e., a discrepancy between the RI of the immersion medium and the RI of the sample). SA due to RI mismatches has many deleterious effects on imaging. Perhaps most important for 3D imaging is that the distance the image plane moves in a sample is not equivalent to the distance traveled by an objective (or stage) during z-stack acquisition. This non-uniform translation along the z axis gives rise to artifactually elongated images (if the objective is immersed in a medium with a higher RI than that of the sample) or compressed images (if the objective is immersed in a medium with a lower RI than that of the sample) and alters the optimal axial sampling rate. In this tutorial, we describe why this distortion occurs, how it impacts quantitative measurements and axial resolution, and what can be done to avoid SA and thereby prevent distorted images. In addition, this tutorial aims to better inform researchers of how to correct RI mismatch-induced axial distortions and provides a practical ImageJ/Fiji-based tool to reduce the prevalence of volumetric measurement errors and lost axial resolution.


Assuntos
Artefatos , Imageamento Tridimensional , Microscopia de Fluorescência , Espalhamento de Radiação , Corantes Fluorescentes/química , Microesferas
4.
J Vasc Interv Radiol ; 31(10): 1545-1550.e1, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32861568

RESUMO

PURPOSE: To characterize the accuracy and consistency of fluoroscope dose index reporting and report rates of occupational radiation safety hardware availability and use, trainee participation in procedures, and optional hardware availability at pilot sites for the American College of Radiology (ACR) Fluoroscopy Dose Index Registry (DIR). MATERIALS AND METHODS: Nine institutions participated in the registry pilot, providing fluoroscopic technical and clinical practice data from 38 angiographic C-arm-type fluoroscopes. These data included measurements of the procedure table and mattress transmission factors and accuracy measurements of the reference-point air kerma (Ka,r) and air kerma-area product (PKA). The accuracy of the radiation dose indices were analyzed for variation over time by 1-way analysis of variance (ANOVA). Sites also self-reported information on availability and use of radiation safety hardware, hardware configuration of fluoroscopes, and trainee participation in procedures. RESULTS: All Ka,r and PKA measurements were within the ±35% regulatory limit on accuracy. The mean absolute difference between correction factors for a given system in fluoroscopic and acquisition mode was 0.03 (95% confidence interval, 0.03-0.03). For the 28 fluoroscopic imaging planes that provided data for 3 time points, ANOVA yielded an F value of 0.134 with an F-critical value of 3.109 (P = .875). CONCLUSIONS: This publication provides the technical and clinical framework pertaining to the ACR Fluoroscopy DIR pilot and offers necessary context for future analysis of the clinical procedure radiation-dose data collected.


Assuntos
Exposição Ocupacional , Doses de Radiação , Exposição à Radiação , Monitoramento de Radiação , Radiografia Intervencionista , Fluoroscopia , Humanos , Exposição Ocupacional/efeitos adversos , Saúde do Trabalhador , Projetos Piloto , Exposição à Radiação/efeitos adversos , Radiografia Intervencionista/efeitos adversos , Sistema de Registros , Medição de Risco , Fatores de Risco , Espalhamento de Radiação , Estados Unidos
5.
Phys Rev Lett ; 125(3): 033604, 2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32745420

RESUMO

We demonstrate Bragg diffraction of the antibiotic ciprofloxacin and the dye molecule phthalocyanine at a thick optical grating. The observed patterns show a single dominant diffraction order with the expected dependence on the incidence angle as well as oscillating population transfer between the undiffracted and diffracted beams. We achieve an equal-amplitude splitting of 14ℏk (photon momenta) and maximum momentum transfer of 18ℏk. This paves the way for efficient, large-momentum beam splitters and mirrors for hot and complex molecules.


Assuntos
Ciprofloxacino/química , Indóis/química , Modelos Químicos , Antibacterianos/química , Interferometria/métodos , Modelos Moleculares , Pigmentos Biológicos/química , Espalhamento de Radiação
7.
Phys Med Biol ; 65(17): 175018, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32640440

RESUMO

The accuracy of delivered radiation dose and the reproducibility of employed radiotherapy methods are key factors for preclinical radiobiology applications and research studies. In this work, ionization chamber (IC) measurements and Monte Carlo (MC) simulations were used to accurately determine the dose rate for total body irradiation (TBI), a classic radiobiologic and immunologic experimental method. Several phantom configurations, including large solid water slab, small water box and rodentomorphic mouse and rat phantoms were simulated and measured for TBI setup utilizing a preclinical irradiator XRad320. The irradiator calibration and the phantom measurements were performed using an ADCL calibrated IC N31010 following the AAPM TG-61 protocol. The MC simulations were carried out using Geant4/GATE to compute absorbed dose distributions for all phantom configurations. All simulated and measured geometries had favorable agreement. On average, the relative dose rate difference was 2.3%. However, the study indicated large dose rate deviations, if calibration conditions are assumed for a given experimental setup as commonly done for a quick determination of irradiation times utilizing lookup tables and hand calculations. In a TBI setting, the reference calibration geometry at an extended source-to-surface distance and a large reference field size is likely to overestimate true photon scatter. Consequently, the measured and hand calculated dose rates, for TBI geometries in this study, had large discrepancies: 16% for a large solid water slab, 27% for a small water box, and 31%, 36%, and 30% for mouse phantom, rat phantom, and mouse phantom in a pie cage, respectively. Small changes in TBI experimental setup could result in large dose rate variations. MC simulations and the corresponding measurements specific to a designed experimental setup are vital for accurate preclinical dosimetry and reproducibility of radiobiological findings. This study supports the well-recognized need for physics consultation for all radiobiological investigations.


Assuntos
Radiometria/instrumentação , Irradiação Corporal Total , Animais , Calibragem , Camundongos , Método de Monte Carlo , Imagens de Fantasmas , Fótons , Ratos , Reprodutibilidade dos Testes , Espalhamento de Radiação
8.
Eur J Vasc Endovasc Surg ; 60(3): 374-385, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32682690

RESUMO

OBJECTIVE: Occupational exposure is a growing concern among the endovascular specialist community. Several types of imaging equipment are available, such as mobile C arms or hybrid rooms, and some have been shown to deliver higher levels of radiation. A literature review was conducted to identify studies reporting dose data during standard (EVAR) and complex abdominal aortic endovascular repair (fenestrated/branched EVAR [F/BEVAR]). METHODS: A search of the MEDLINE and the Cochrane databases was performed by two independent investigators using the medical subject heading terms "aortic aneurysms", "radiation", and "humans" over a search period of 10 years. Studies with full text available in English and reporting radiation data independently from the imaging equipment type were included. Experimental studies were excluded. RESULTS: The lowest dose-area product levels during EVAR and F/BEVAR were identified in hybrid rooms, while the highest were with fixed systems. When adherence to the as low as reasonably achievable principles was stipulated by the authors, dose reports tended to be among the lowest. Several studies, especially of F/BEVAR, report concerning levels of radiation for both patients and staff. CONCLUSION: Modern imaging equipment type, team involvement with radiation management, and the support of recent imaging technologies such as fusion help to reduce the dose delivered during standard and complex EVAR. Investment in modern imaging technology should be considered in every centre providing endovascular management of aortic aneurysms.


Assuntos
Aorta Abdominal/cirurgia , Aneurisma da Aorta Abdominal/cirurgia , Procedimentos Endovasculares , Exposição Ocupacional , Saúde do Trabalhador , Salas Cirúrgicas , Doses de Radiação , Exposição à Radiação , Radiografia Intervencionista , Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Procedimentos Endovasculares/efeitos adversos , Humanos , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/prevenção & controle , Exposição à Radiação/efeitos adversos , Exposição à Radiação/prevenção & controle , Proteção Radiológica , Radiografia Intervencionista/efeitos adversos , Medição de Risco , Fatores de Risco , Espalhamento de Radiação
9.
10.
Opt Express ; 28(12): 18224-18240, 2020 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-32680023

RESUMO

Recently the acquisition of the time-resolved reflection matrix was demonstrated based on spectral domain optical coherence tomography. In principle, the matrix describes the linear dependence of the OCT signal received from different depths on the field which is incident to the scattering sample. Knowledge of the matrix, hence, enables beam shaping to selectively enhance the received signal, for example to increase the penetration depth when imaging turbid media. We investigate the impact of image artefacts on the approach. Phase conjugation is shown to enhance the OCT signal, but not autocorrelation and mirror artefacts. Imaging applications are demonstrated indicating the potential for future in-vivo studies on biotissues.


Assuntos
Algoritmos , Artefatos , Luz , Espalhamento de Radiação , Tomografia de Coerência Óptica/métodos , Interferometria/métodos , Fenômenos Ópticos , Fatores de Tempo , Tomografia de Coerência Óptica/instrumentação
11.
Proc Natl Acad Sci U S A ; 117(26): 14645-14656, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32522873

RESUMO

Focusing waves inside inhomogeneous media is a fundamental problem for imaging. Spatial variations of wave velocity can strongly distort propagating wave fronts and degrade image quality. Adaptive focusing can compensate for such aberration but is only effective over a restricted field of view. Here, we introduce a full-field approach to wave imaging based on the concept of the distortion matrix. This operator essentially connects any focal point inside the medium with the distortion that a wave front, emitted from that point, experiences due to heterogeneities. A time-reversal analysis of the distortion matrix enables the estimation of the transmission matrix that links each sensor and image voxel. Phase aberrations can then be unscrambled for any point, providing a full-field image of the medium with diffraction-limited resolution. Importantly, this process is particularly efficient in random scattering media, where traditional approaches such as adaptive focusing fail. Here, we first present an experimental proof of concept on a tissue-mimicking phantom and then, apply the method to in vivo imaging of human soft tissues. While introduced here in the context of acoustics, this approach can also be extended to optical microscopy, radar, or seismic imaging.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Ultrassonografia/métodos , Acústica , Análise de Fourier , Humanos , Perna (Membro)/diagnóstico por imagem , Imagens de Fantasmas , Espalhamento de Radiação
12.
Phys Med Biol ; 65(18): 185008, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32516759

RESUMO

In vivo dosimetry methods can verify the prescription dose is delivered to the patient during treatment. Unfortunately, in exit dosimetry, the megavoltage image is contaminated with patient-generated scattered photons. However, estimation and removal of the effect of this fluence improves accuracy of in vivo dosimetry methods. This work develops a 'tri-hybrid' algorithm combining analytical, Monte Carlo (MC) and pencil-beam scatter kernel methods to provide accurate estimates of the total patient-generated scattered photon fluence entering the MV imager. For the multiply-scattered photon fluence, a modified MC simulation method was applied, using only a few histories. From each second- and higher-order interaction site in the simulation, energy fluence entering all pixels of the imager was calculated using analytical methods. For photon fluence generated by electron interactions in the patient (i.e. bremsstrahlung and positron annihilation), a convolution/superposition approach was employed using pencil-beam scatter fluence kernels as a function of patient thickness and air gap distance, superposed on the incident fluence distribution. The total patient-scattered photon fluence entering the imager was compared with a corresponding full MC simulation (EGSnrc) for several test cases. These included three geometric phantoms (water, half-water/half-lung, computed tomography thorax) using monoenergetic (1.5, 5.5 and 12.5 MeV) and polyenergetic (6 and 18 MV) photon beams, 10 × 10 cm2 field, source-to-surface distance 100 cm, source-to-imager distance 150 cm and 40 × 40 cm2 imager. The proposed tri-hybrid method is demonstrated to agree well with full MC simulation, with the average fluence differences and standard deviations found to be within 0.5% and 1%, respectively, for test cases examined here. The method, as implemented here with a single CPU (non-parallelized), takes ∼80 s, which is considerably shorter compared to full MC simulation (∼30 h). This is a promising method for fast yet accurate calculation of patient-scattered fluence at the imaging plane for in vivo dosimetry applications.


Assuntos
Equipamentos e Provisões Elétricas , Dosimetria in Vivo/métodos , Fótons , Espalhamento de Radiação , Algoritmos , Humanos , Método de Monte Carlo , Imagens de Fantasmas , Tomografia Computadorizada por Raios X
13.
Phys Med Biol ; 65(16): 165009, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32512540

RESUMO

The University of Washington (UW) Clinical Neutron Therapy System (CNTS) has been used to treat over 3300 patients. Treatment planning for these patients is currently performed using an MV x-ray model in Pinnacle® adapted to fit measurements of fast neutron output factors, wedge factors, depth-dose and lateral profiles. While this model has provided an adequate representation of the CNTS for 3D conformal treatment planning, later versions of Pinnacle did not allow for isocentric gantry rotation machines with a source-to-axis distance of 150 cm. This restriction limited the neutron model to version 9.0 while the photon and electron treatment planning at the UW had moved on to newer versions. Also, intensity modulated neutron therapy (IMNT) is underdevelopment at the UW, and the Pinnacle neutron model developed cannot be used for inverse treatment planning. We have used the MCNP6 Monte Carlo code system to develop Collapsed Cone (CC) and Singular Value Decomposition (SVD) neutron scattering kernels suitable for integration into the RayStation treatment planning system. Kernels were generated for monoenergetic neutrons with energies ranging from 1 keV to 51 MeV, i.e. the energy range most relevant to the CNTS. Percent depth dose (PDD) profiles computed in RayStation for the CC and SVD kernels are in excellent agreement with each other for depths beyond the beam's dose build-up region (depths greater than about 1.7 cm) for open 2.8 × 2.8 cm2, 10.3 × 10.3 cm2, and 28.8 × 32.8 cm2 fields. Lateral profiles at several depths, as well as the PDD, calculated using the CC kernels in RayStation for the full CNTS energy spectrum pass a 3%/3 mm gamma test for field sizes of 2.8 × 2.8 cm2, 10.0 × 10.3 cm2, and 28.8 × 32.8 cm2.


Assuntos
Algoritmos , Nêutrons Rápidos/uso terapêutico , Modelos Teóricos , Método de Monte Carlo , Imagens de Fantasmas , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Dosagem Radioterapêutica , Espalhamento de Radiação
14.
Artigo em Japonês | MEDLINE | ID: mdl-32565514

RESUMO

The purpose of this study was to measure the scatter radiation intensity during transforaminal lumbar interbody fusion using a mobile C-arm system (Arcadis Orbic 3D; Siemens) and minimize radiation exposure. Dosimetry was performed with anterior-posterior and lateral continuous fluoroscopy, and cone beam computed tomography (CT). A scaffold tower (L: 300 cm×W: 200 cm×H: 150 cm) was built with radiation-resistant paper cylinders at intervals of 50 cm and plastic joints over the bed, and 100 optically stimulated luminescence dosimeters (nanoDot; Nagase Landauer) were placed on each joint. A human torso phantom from head to pelvis (Kyoto Kagaku) was positioned on the bed in a prone position. The scatter radiation dose in a lateral view was highest on the X-ray tube side at the height of 100 cm (170.5 µGy/min). The scatter radiation dose increased significantly on the X-ray tube side during lateral continuous fluoroscopy. Continuous change of surgeons' standing positions is important to minimize radiation exposure received by a specific surgeon.


Assuntos
Exposição à Radiação , Fluoroscopia , Humanos , Vértebras Lombares/diagnóstico por imagem , Imagens de Fantasmas , Doses de Radiação , Radiometria , Espalhamento de Radiação
15.
Nat Methods ; 17(7): 681-684, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32451477

RESUMO

Time-resolved crystallography with X-ray free-electron lasers enables structural characterization of light-induced reactions on ultrafast timescales. To be biologically and chemically relevant, such studies must be carried out in an appropriate photoexcitation regime to avoid multiphoton artifacts, a common issue in recent studies. We describe numerical and experimental approaches to determine how many photons are needed for single-photon excitation in microcrystals, taking into account losses by scattering.


Assuntos
Cristalografia por Raios X/métodos , Fótons , Radiação Eletromagnética , Lasers , Luz , Espalhamento de Radiação
16.
Phys Med Biol ; 65(17): 175003, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32422618

RESUMO

A maximum likelihood approach to the problem of calculating the proton paths inside the scanned object in proton computed tomography is presented. Molière theory is used for the first time to derive a physical model that describes proton multiple Coulomb scattering, avoiding the need for the Gaussian approximation currently used. To enable this, the proposed method approximates proton paths with cubic Bézier curves and subsequently maximizes the path likelihood through parametric optimization, based on the Molière model. Results from the Highland formula-based Gaussian approximation are also presented for comparison. The simplex method is utilized for optimisation. The scattering properties of the material(s) of the scanned object are taken into account by appropriately calculating the scattering parameters from the stopping power map that is calculated/updated at every iteration of the algebraic reconstruction process. Proton track length constraint imposed by the proton energy loss is accounted for. The method is also applied in the case that no exit angle data are measured. Geant4 Monte Carlo simulations were performed for model validation. Our results show that use of Molière probability density function for modelling the multiple Coulomb scattering presents a modest 2% accuracy improvement over the Gaussian approximation and most-likely-path method. Simulations of voxelized phantom showed no essential benefit from the inclusion of the material information into the optimization, while path optimization with energy constraint slightly increased path resolution in a bone/water interface phantom. Method error was found to depend on energy, proton track-length within the medium, and proportion of data filtering.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Prótons , Espalhamento de Radiação , Tomografia Computadorizada por Raios X , Algoritmos , Funções Verossimilhança , Modelos Teóricos , Método de Monte Carlo , Distribuição Normal , Imagens de Fantasmas
17.
Phys Med Biol ; 65(15): 155013, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32408276

RESUMO

By collecting photons scattered out of the therapy beam, scatter imaging creates images of the treated volume. Two phantoms were used to assess the possible application of scatter imaging for markerless tracking of lung tumors during stereotactic body radiation therapy (SBRT) treatment. A scatter-imaging camera was assembled with a CsI flat-panel detector and a 5 mm diameter pinhole collimator. Scatter images were collected during the irradiation of phantoms with megavoltage photons. To assess scatter image quality, spherical phantom lung tumors of 2.1-2.8 cm diameters were placed inside a static, anthropomorphic phantom. To show the efficacy of the technique with a moving target (3 cm diameter), the position of a simulated tumor was tracked in scatter images during sinusoidal motion (15 mm amplitude, 0.25 Hz frequency) in a dynamic lung phantom in open-field, dynamic conformal arc (DCA), and volumetric modulated arc therapy (VMAT) deliveries. Anatomical features are identifiable on static phantom scatter images collected with 10 MU of delivered dose (2.1 cm diameter lung tumor contrast-to-noise ratio of 4.4). The contrast-to-noise ratio increases with tumor size and delivered dose. During dynamic motion, the position of the 3.0 cm diameter lung tumor was identified with a root-mean-square error of 0.8, 1.2, and 2.9 mm for open field (0.3 s frame integration), DCA (0.5 s), and VMAT (0.5 s), respectively. Based on phantom studies, scatter imaging is a potential technique for markerless lung tumor tracking during SBRT without additional imaging dose. Quality scatter images may be collected at low, clinically relevant doses (10 MU). Scatter images are capable of sub-millimeter tracking precision, but modulation decreases accuracy.


Assuntos
Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/radioterapia , Imagem Molecular/instrumentação , Imagens de Fantasmas , Radiocirurgia/instrumentação , Espalhamento de Radiação , Humanos , Radioterapia de Intensidade Modulada
18.
AAPS PharmSciTech ; 21(5): 152, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32440782

RESUMO

The present study investigates concomitant processes of solid-state disordering and oxidation of simvastatin during milling. The separate dry ball milling of crystalline and amorphous powders of simvastatin were conducted at ambient temperature for 10 and 60 min each. The relative crystallinity was determined using X-ray scattering and oxidative degradation was analyzed using liquid chromatography. The physical and chemical transformations in the milled powder were evaluated using modulated differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. The disordering during milling of the crystalline powder was found to progressively decrease the crystallinity. For the amorphous starting material, milling for 10 min induced a large extent of recrystallization, while milling for 60 min largely re-amorphized the powder. This solid-state disordering and/or ordering were accompanied by progressive air oxidation during milling. The infrared spectroscopic analysis revealed the molecular manifestations associated with the physicochemical transformations in the disordered solid states. The melting point of simvastatin depressed systematically with the increase in the degree of disorder as well as the degradation. The in situ cooling in DSC of milled samples from their molten state led to the formation of the co-amorphous phase between the drug and degradation products, which showed a consistent increase in glass transition temperature with the increase in the content of degradation products. The study overall demonstrates the solid-state re-ordering and disordering of crystalline and amorphous simvastatin accompanied by chemical degradation as the consequence of the mechano-activation.


Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/química , Sinvastatina/química , Varredura Diferencial de Calorimetria , Análise Diferencial Térmica , Composição de Medicamentos , Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Luz , Transição de Fase , Pós , Espalhamento de Radiação , Sinvastatina/administração & dosagem , Espectrofotometria Infravermelho , Raios X
19.
AAPS PharmSciTech ; 21(5): 135, 2020 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-32419073

RESUMO

This study aimed to develop a self-emulsifying drug delivery system (SEDDS) of celecoxib (CEL) for suppressed delay in oral absorption under impaired gastric motility. A pseudo-ternary phase diagram was constructed for the determination of the optimal component ratio in SEDDS of CEL (SEDDS/CEL), and the SEDDS/CEL was physicochemically characterized. A pharmacokinetic study on orally dosed CEL samples (5-mg CEL/kg) was carried out in normal and propantheline (PPT)-treated rats to mimic impaired gastric motility. SEDDS/CEL rapidly formed a fine emulsion with a mean size of 147 nm in distilled water and significantly improved the dissolution behavior of CEL under pH 1.2 condition with a 20-fold higher dissolved amount than crystalline CEL. In normal rats, orally dosed SEDDS/CEL provided a 4.6-fold higher systemic exposure than that of crystalline CEL, due to the improved dissolution properties of CEL. Crystalline CEL showed delayed and decreased oral absorption of CEL in PPT-treated rats as evidenced by a 6.9-h-delayed mean absorption time and only 12% of the systemic exposure of CEL compared with those in normal rats. In contrast, SEDDS/CEL enhanced the oral absorption of CEL with a 14.6-fold higher systemic exposure with significant suppression of delay in absorption than crystalline CEL even in PPT-treated rats. SEDDS/CEL could be an efficacious option for suppressing delay in CEL absorption even under impairment of gastric motility, possibly leading to rapid and reproducible management of severe acute pain.


Assuntos
Celecoxib/administração & dosagem , Inibidores de Ciclo-Oxigenase 2/administração & dosagem , Absorção Intestinal , Gastropatias/metabolismo , Administração Oral , Animais , Disponibilidade Biológica , Celecoxib/farmacocinética , Inibidores de Ciclo-Oxigenase 2/farmacocinética , Sistemas de Liberação de Medicamentos , Emulsões , Motilidade Gastrointestinal , Luz , Masculino , Tamanho da Partícula , Propantelina/farmacologia , Ratos , Ratos Sprague-Dawley , Espalhamento de Radiação , Solubilidade , Gastropatias/induzido quimicamente
20.
Curr Opin Ophthalmol ; 31(4): 225-233, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32398417

RESUMO

PURPOSE OF REVIEW: This review outlines ophthalmic diagnostic systems, which objectively evaluates the human visual system and its potential beyond that of Snellen acuity. RECENT FINDINGS: Advances in ophthalmic diagnostic systems have allowed for a deeper understanding of the optical principles of the human eye and have created the opportunity to evolve our current standards of vision assessment beyond Snellen acuity charts. Definitive comparative and validation trials will continue to be necessary in order for these advanced diagnostics to gain more widespread acceptance in the specialty, in addition to providing the guidance on the specific indications and utilities. SUMMARY: Advancements in wavefront analysis, light scatter measurements, and adaptive optics technologies can provide greater insight into an individual optical system's potential and irregularities. Modalities that test for anterior corneal surface and whole eye aberrations, light scatter and contrast sensitivity can be an excellent educational tool for our patients to help them better understand their visual dysfunction and can prove useful for medical or surgical decision-making.


Assuntos
Sensibilidades de Contraste/fisiologia , Córnea/fisiologia , Refração Ocular/fisiologia , Aberrações de Frente de Onda da Córnea/fisiopatologia , Humanos , Luz , Espalhamento de Radiação , Testes Visuais , Acuidade Visual/fisiologia
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