Line Spread Research Articles

Interaction and instability of air films between bituminous coal surfaces and surfactant droplets

While the suppression of airborne coal particulates with water and surfactant sprays has been widely used in underground coal mines, the microscopic mechanism involved during the attachment process between water droplets and dust particles has not been well understood. In this work, both the interaction forces and instability of air films between aqueous droplets and coal surfaces are studied by monitoring the evolution of spatial and temporal thickness profiles of the air films. The measurements are conducted with both non-ionic and anionic surfactants. The results of this work show that the air film between the water droplet and the bituminous coal surface collapses at a critical rupture thickness of 104 nm, which is followed by a rapid spreading of the three-phase contact line. It has been found that both the critical rupture thickness and kinetics of film thinning increase with increasing surfactant concentrations regardless of the types of surfactants. An analysis of the spatiotemporal thickness profiles using the Reynolds equation shows that an attractive force is present across an air film. This force is found to be an electrostatic force. The force becomes more attractive with increasing surfactant concentrations of the aqueous solutions. The present work sheds new light on the capture of dust particles by water and surfactant sprays at a molecular level.

Measuring method for the line spread function of specular reflection

Gloss is evaluated based on not only the intensity of reflected light but also the sharpness of the light source image. In this paper, we discuss the line spread function of specular reflection (SR-LSF). We developed a measurement apparatus for the SR-LSF based on the visual inspection of gloss. The measurement results of six types of samples with different glossiness values are shown. These samples were measured using the point spread function of specular reflection reported previously by the authors to verify the SR-LSF. It is shown that the SR-LSF can be measured easily and efficiently from an image recorded for visual inspection.

Preclinical Single Photon Emission Computed Tomography of Alpha Particle-Emitting Radium-223.

Objective: Dose optimization and pharmacokinetic evaluation of α-particle emitting radium-223 dichloride (223RaCl2) by planar γ-camera or single photon emission computed tomography (SPECT) imaging are hampered by the low photon abundance and injected activities. In this study, we demonstrate SPECT of 223Ra using phantoms and small animal in vivo models. Methods: Line phantoms and mice bearing 223Ra were imaged using a dedicated small animal SPECT by detecting the low-energy photon emissions from 223Ra. Localization of the therapeutic agent was verified by whole-body and whole-limb autoradiography and its radiobiological effect confirmed by immunofluorescence. Results: A state-of-the-art commercial small animal SPECT system equipped with a highly sensitive collimator enables collection of sufficient counts for three-dimensional reconstruction at reasonable administered activities and acquisition times. Line sources of 223Ra in both air and in a water scattering phantom gave a line spread function with a full-width-at-half-maximum of 1.45 mm. Early and late-phase imaging of the pharmacokinetics of the radiopharmaceutical were captured. Uptake at sites of active bone remodeling was correlated with DNA damage from the α particle emissions. Conclusions: This work demonstrates the capability to noninvasively define the distribution of 223RaCl2, a recently approved α-particle-emitting radionuclide. This approach allows quantitative assessment of 223Ra distribution and may assist radiation-dose optimization strategies to improve therapeutic response and ultimately to enable personalized treatment planning.

Novel calcium phosphate coated calcium silicate-based cement: in vitro evaluation

Calcium silicate-based cements are known for their wide applications in dentistry and orthopedics. The alkaline pH (up to 12) of these cements limits their application in other orthopedic areas. In this study, the effect of dicalcium phosphate dihydrate (DCPD) coating on set cement on pH reduction and biocompatibility improvement was examined. Samples with 0 and 10 weight ratio DCPD were prepared and characterized by XRD, FTIR, and SEM. The DCPD coating on the set cement was performed by a 7 d immersion in 1% monocalcium phosphate (MCP) solution and characterized by XRD, FTIR, SEM, and EDX. Also, the compressive strength and cytotoxicity of the samples were tested. The results showed that DCPD coating did not significantly change the compressive strength of the cement, but by decreasing the pH of the culture medium to the physiological range, it led to enhance adhesion, spreading and proliferation of human osteosarcoma cell line (Saos-2). The novel DCPD coated calcium silicate-based cement could be served as a bulk or porous bone substitute and scaffold.

An improvement in automatic MTF measurement in CT images using an edge of the PMMA phantom

We have developed an improved method of modulation transfer function (MTF) measurement using an edge of the polymethyl methacrylate (PMMA) phantom which is normally positioned for computed tomography dose index (CTDI) measurement. In CTDI measurements, the peripheral holes of the PMMA phantom are set at the 3, 6, 9 and 12 o’clock positions. The upper edge of the phantom image has a hole, which precludes its use in calculating the MTF. To circumvent this, the phantom image was homogenized by replacing all pixel values inside the phantom with the median value of the phantom pixels. Subsequently, we were able to calculate the MTF by measuring the edge spread function (ESF) curve, calculate the line spread function (LSF) curve, and obtain the MTF curve by Fourier transform. The resulting MTF curve using our proposed method was then compared with the tail replacement method which had been proposed previously. Our method is superior to the tail replacement method which results in some inhomogeneity of the ESF curve in the part inside the phantom.

WAPL-Dependent Repair of Damaged DNA Replication Forks Underlies Oncogene-Induced Loss of Sister Chromatid Cohesion.

Premature loss of sister chromatid cohesion at metaphase is a diagnostic marker for different cohesinopathies. Here, we report that metaphase spreads of many cancer cell lines also show premature loss of sister chromatid cohesion. Cohesion loss occurs independently of mutations in cohesion factors including SA2, a cohesin subunit frequently inactivated in cancer. In untransformed cells, induction of DNA replication stress by activation of oncogenes or inhibition of DNA replication is sufficient to trigger sister chromatid cohesion loss. Importantly, cell growth under conditions of replication stress requires the cohesin remover WAPL. WAPL promotes rapid RAD51-dependent repair and restart of broken replication forks. We propose that active removal ofcohesin allows cancer cells to overcome DNA replication stress. This leads to oncogene-induced cohesion loss from newly synthesized sister chromatids that may contribute to genomic instability and likely represents a targetable cancer cell vulnerability.

CT performance of compact X-ray source with small focal spot using a 950 keV linear accelerator

A 950 keV X-ray source with small focal spot using a linear accelerator has been developed. By installing a focusing mechanism of electron beam, smaller focal spot (0.3 mm in FWHM of the line spread function) is successfully achieved at 950 keV. 9.3 GHz (X-band) radio frequency is used for accelerating electrons in order to make the size of X-ray source smaller, compared to lower radio frequency such as 3.0 GHz (S-band). Size and weight of the developed X-ray source are W 600 mm × D 800 mm × H 500 mm and 230 kg, respectively. Clearer transmission images using a rectangular groove sample are obtained with small spot setup, compared to conventional one. CT images are also obtained for an engine block, and we demonstrated that advantage of 950 keV X-ray source for CT imaging such as improvement of interior visibility and decrease of artefact, compared to a 450 kV X-ray source. Therefore, we are convinced that this 950 keV X-ray source is widely useful for industrial non-destructive inspection of large structures, because of compactness, high transmission ability and spatial resolution.

A Radio-Nano-Platform for T1/T2 Dual-Mode PET-MR Imaging.

PurposeThis study aimed to develop a chelate-free radiolabeled nanoparticle platform for simultaneous positron emission tomography (PET) and magnetic resonance (MR) imaging that provides contrast-enhanced diagnostic imaging and significant image quality gain by integrating the high spatial resolution of MR with the high sensitivity of PET.MethodsA commercially available super-paramagnetic iron oxide nanoparticle (SPION) (Feraheme®, FH) was labeled with the [89Zr]Zr using a novel chelate-free radiolabeling technique, heat-induced radiolabeling (HIR). Radiochemical yield (RCY) and purity (RCP) were measured using size exclusion chromatography (SEC) and radio-thin layer chromatography (radio-TLC). Characterization of the non-radioactive isotope 90Zr-labeled FH was performed by transmission electron microscopy (TEM). Simultaneous PET-MR phantom imaging was performed with different 89Zr-FH concentrations. The MR quantitative image analysis determined the contrast-enhancing properties of FH. The signal-to-noise ratio (SNR) and full-width half-maximum (FWHM) of the line spread function (LSF) were calculated before and after co-registering the PET and MR image data.ResultsHigh RCY (92%) and RCP (98%) of the [89Zr]Zr-FH product was achieved. TEM analysis confirmed the 90Zr atoms adsorption onto the SPION surface (≈ 10% average radial increase). Simultaneous PET-MR scans confirmed the capability of the [89Zr]Zr-FH nano-platform for this multi-modal imaging technique. Relative contrast image analysis showed that [89Zr]Zr-FH can act as a dual-mode T1/T2 contrast agent. For co-registered PET-MR images, higher spatial resolution (FWHM enhancement ≈ 3) and SNR (enhancement ≈ 8) was achieved at a clinical dose of radio-isotope and Fe.ConclusionOur results demonstrate FH is a highly suitable SPION-based platform for chelate-free labeling of PET tracers for hybrid PET-MR. The high RCY and RCP confirmed the robustness of the chelate-free HIR technique. An overall image quality gain was achieved compared to PET- or MR-alone imaging with a relatively low dosage of [89Zr]Zr-FH. Additionally, FH is suitable as a dual-mode T1/T2 MR image contrast agent.

The schoolboys’ revenge: how the golden line entered classical scholarship

AbstractThe golden line, a Latin versification exercise in British classrooms since at least 1612, appears to have no basis in the classical tradition. It was resisted by the academy for decades — if not centuries. Then, as Latin versification ceded its central role in schools and universities, resistance withered. New generations of scholars had never encountered the golden line as a composition exercise, and they saw instead the golden line as a critical tool for interpreting Latin poetry. After the 1950s, the golden line spread to Italy, Spain, Belgium, Germany, France, and beyond. A classroom exercise helped shape scholarship worldwide. Yet the golden line is an even more striking example of scholarship from below, because it thrived due to its documented appeal to the students who identified and composed them. From the 1600s until today, students have expressed pride and joy in identifying and composing golden lines. Student preferences often shape pedagogical canons and classroom practice, but the golden line went still further. Today, Latinists worldwide analyse poets of the classical canon by counting and discussing their golden lines. Student preferences for a school exercise have changed not only pedagogy but scholarly practice.

Effect of correction methods on image resolution of myocardial perfusion imaging using single photon emission computed tomography combined with computed tomography hybrid systems

Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) gamma camera has been widely utilized for diagnosis and risk stratification of ischemic heart disease. Objective; The purpose of this study is to evaluate the effect of different correction methods on image resolution of MPI using the SPECT/CT hybrid system. Materials and Method; A total of 114 patients, 43 females and 71 males, patient’s raw data were processed and analyzed using Attenuation correction (AC), Scatter correction (SC), Both attenuation and scatter correction together (ACSC) and no-correction (NC). The short axis (coronal) slices resulted from the raw data reconstruction were chosen to draw the curve profile to identify the line spread function on the image to create the FWHM curve. Profile statistics were calculated to obtain the value of FWHM. Statistical analysis was made for the calculated FWHM values for AC, SC, ACSC, and NC to determine the best image resolution. Results; It turns out that applying the SC alone yields better FWHM value (8.13), compared to AC (8.77), and ACSC (8.72). Both AC and ACSC had better FWHM compared to NC (8.91). Conclusion; The study indicates that the intercomparison between the four avaliable correction conditions the image resolution has been significantly improved by using scatter correction, attenuation correction, and both methods together when compared with the non-corrected image. Also it was found that the scatter correction condition is superior in the image resolution than the other correction condition in the reconstruction of SPECT/CT myocardial perfusion images.

Line-Based Modulation Transfer Function Measurement of Pixelated Displays

This paper proposes a line-based method for measuring the modulation transfer function (MTF) of a display. In this method, the spatial distribution of a single line that is displayed in a small region of the screen is analyzed. This is performed by capturing the displayed line by a light measuring device (LMD). The square sampling grid of the LMD is set slightly slanted relative to the displayed line so that the line is recorded with various offsets with respect to the sampling positions. By analyzing a supersampled 1D line spread function generated from a small region of interest (ROI) in the image of the captured line, the display MTF is estimated. The convolution theorem is used to compensate the display MTF for the underestimation related to the spatial performance or MTF of the LMD. Thereby, accurate display MTF results are obtained for a wide range of pixel ratio, i.e., the number of pixels of the measurement device per display pixel interval. The proposed method was validated using computer-generated images of a model display with an RGB stripe subpixel arrangement and a model LMD. The utilization of a low pixel ratio enables the measurement to be performed using a small lens and long working distance. In addition, the small size of the employed ROI significantly reduces the computational cost and allows the use of a low-resolution camera.

Empirical model of magnetic field line spreading in isotropic turbulence with zero mean field

In many cases, the random walk of magnetic field line in isotropic turbulence with zero mean field is appropriated to describe the transport of energetic particles in the interstellar medium of our Galaxy. To understand the transport, our previous work determined the asymptotic field line diffusion coefficient by using Corrsin’s hypothesis and presumed models of field line spreading. Two of those models of field line spreading are the diffusive decorrelation (DD) model and the random ballistic decorrelation (RBD) model. The variances of the field line displacement in, say, the x direction for the DD and RBD models are assumed as and , respectively. τ is the field line displacement parameter defined as dτ = ds/B, where s is the arc length along the field line and B is the magnitude of the total magnetic field. D is the asymptotic diffusion coefficient, b is the rms magnetic fluctuation and is the ultrascale. Comparing with simulation results, the DD and RBD models predict the D values with ⩽ 15% error and ⩽ 21% error, respectively. To improve the theoretical model empirically, in this work, we assume that the proper model the variance is , where β is a proportional constant and α is an exponent. We extrapolate β with the proportional constants of DD and RBD models. Comparing with the simulation result of Kolmogorov turbulence, we obtain α = 0.8694. To test validity of the model, we compare the theoretical results of (formulated from Kolmogorov turbulence) with simulation results of two other turbulences: IroshnikovKraichnan turbulence and weak turbulence. The theoretical results of the empirical model match the computer simulation results very well (with ⩽ 0.9% error).

Positron range effects of 66Ga in small-animal PET imaging

PurposeGallium-66 is a non-conventional positron emitter that stands out not only for its high potential to label peptides, proteins and antibodies, but also because it can provide spatio-temporal information of relatively slow physiological processes in the body due to its conveniently long half-life of 9.5 h. However, 66Ga emits the most energetic positrons for PET imaging. The lack of information of the positron range effect on spatial resolution for this positron emitter is an issue, particularly in preclinical imaging. MethodsThe line spread function (LSF) in tissue-equivalent materials with densities between 0.2 and 1.93 g/cm3 was obtained with 66Ga and 18F. A complementary study with the NEMA NU 4-2008 image quality phantom is also included. ResultsHigh-energy positrons moving in lower density materials produce far-reaching activity distributions. The LSFs were characterized with Lorentzian-Gaussian fits, with spatial resolution (FWHM) in the 2.14–3.2 mm range, and long tails extending a few tens of mm depending on the material type and density. A narrowing of the LSF was observed for lung-equivalent materials, indicating the lack of enough material for the positron annihilation to take place. The NEMA NU 4-2008 image quality phantom produced blurred images, notoriously observed in the hot and cold cylinders used for evaluation of recovery coefficients (RC) and spill-over ratios (SOR), producing very low RC and very large SOR. ConclusionsQuantitative PET imaging with the non-conventional 66Ga is hampered due to the large range of its high-energy positrons affecting both spatial resolution and activity concentration quantification.

Gravity flow test comparisons for mildly thick consistency.

Simple measurement tools that provide objective information about the consistency of thickened liquids have received increasing attention given possible application to clinical practice for dysphagia. The International Dysphagia Diet Standardization Initiative (IDDSI) advocates the use of the IDDSI Flow Test for measuring thickness and verifying a prescribed level of consistency. This study compares gravity flow test measurements taken with two 10-ml syringes of starch and gum-thickened samples prepared to a mildly thick consistency using product label information. One of the 10-ml syringes met IDDSI specification and the other 10-ml syringe did not. Thickened samples also were measured using the line spread apparatus. The results showed that two syringes yielded significantly different gravity flow test measurements, often resulting in changes to the classification level of thickness. There was no effect of thickening agent. Line spread measurements did not vary from one another. Study findings indicate the importance of continued testing with the IDDSI Flow Test and education/awareness about the use of the IDDSI reference syringe. An essential aspect about the use of thickened liquids in dysphagia management is that beverage preparations represent their prescribed level of modification. The findings of this study indicate the importance of following syringe specifications when conducting gravity flow testing using the IDDSI methodology. The implication is that the wrong 10-ml syringe could result in errant clinical decisions in determining the accuracy of texture modifications, resulting in care providers who are more likely to over or under thicken modifications to achieve a targeted level of thickness.

Line Spread Function of Specular Reflection and Gloss Unevenness Analysis

In this paper, we examined the physical meaning of the widely used gloss evaluation. Gloss is one of the important qualities for materials. A visual test of the sharpness of a specular reflection image, i.e. gloss, on the surface of materials is often performed to estimate the gloss of materials. If the specular reflection image is sharp, we estimate that it has high gloss. This means that gloss can be estimated by measuring the sharpness of the specular reflection image. In this case, a line light source such as a fluorescent lamp is often used. Here we call it the line light source observation method. We developed a measurement apparatus based on the line light source observation method. As a result of experimental verification, it is confirmed that the Line Spread Function of Specular Reflection (SR-LSF) can be derived from the line light source observation images. However, the reflected image of line light source observation method is considered to be strictly different from SR-LSF. On the other hand, it is clarified that the line source observation method is an approximate SR-LSF measurement method. We also introduce the reconstruct method of gloss unevenness image by following visual observation conditions and image processing in human brain.

Precise Radial Velocities of Cool Low-mass Stars with iSHELL

Abstract The coolest dwarf stars are intrinsically faint at visible wavelengths and exhibit rotationally modulated stellar activity from spots and plages. It is advantageous to observe these stars at near-infrared (NIR) wavelengths (1–2.5 μm) where they emit the bulk of their bolometric luminosity and are most quiescent. In this work, we describe our methodology and results in obtaining precise radial velocity (RV) measurements of low-mass stars using K-band spectra taken with the R ∼ 80,000 iSHELL spectrograph and the NASA Infrared Telescope Facility using a methane isotopologue gas cell in the calibration unit. Our novel analysis pipeline extracts RVs by minimizing the rms of the residuals between the observed spectrum and a forward model. The model accounts for the gas cell, tellurics, blaze function, multiple sources of quasi-sinusoidal fringing, and line spread function of the spectrograph. The stellar template is derived iteratively using the target observations themselves through averaging barycenter-shifted residuals. We have demonstrated 5 m s−1 precision over one-year timescales for the M4 dwarf Barnard’s Star and K dwarf 61 Cygni A, and 3 m s−1 over a month for the M2 dwarf GJ 15 A. This work demonstrates the potential for iSHELL to determine dynamical masses for candidate exoplanets discovered with the NASA Transiting Exoplanet Survey Satellite mission, and to search for exoplanets orbiting moderately active and/or young K & M dwarfs.

Real-time algorithm for Poissonian noise reduction in low-dose fluoroscopy: performance evaluation

BackgroundQuantum noise intrinsically limits the quality of fluoroscopic images. The lower is the X-ray dose the higher is the noise. Fluoroscopy video processing can enhance image quality and allows further patient’s dose lowering. This study aims to assess the performances achieved by a Noise Variance Conditioned Average (NVCA) spatio-temporal filter for real-time denoising of fluoroscopic sequences. The filter is specifically designed for quantum noise suppression and edge preservation. It is an average filter that excludes neighborhood pixel values exceeding noise statistic limits, by means of a threshold which depends on the local noise standard deviation, to preserve the image spatial resolution. The performances were evaluated in terms of contrast-to-noise-ratio (CNR) increment, image blurring (full width of the half maximum of the line spread function) and computational time. The NVCA filter performances were compared to those achieved by simple moving average filters and the state-of-the-art video denoising block matching-4D (VBM4D) algorithm. The influence of the NVCA filter size and threshold on the final image quality was evaluated too.ResultsFor NVCA filter mask size of 5 × 5 × 5 pixels (the third dimension represents the temporal extent of the filter) and a threshold level equal to 2 times the local noise standard deviation, the NVCA filter achieved a 10% increase of the CNR with respect to the unfiltered sequence, while the VBM4D achieved a 14% increase. In the case of NVCA, the edge blurring did not depend on the speed of the moving objects; on the other hand, the spatial resolution worsened of about 2.2 times by doubling the objects speed with VBM4D. The NVCA mask size and the local noise-threshold level are critical for final image quality. The computational time of the NVCA filter was found to be just few percentages of that required for the VBM4D filter.ConclusionsThe NVCA filter obtained a better image quality compared to simple moving average filters, and a lower but comparable quality when compared with the VBM4D filter. The NVCA filter showed to preserve edge sharpness, in particular in the case of moving objects (performing even better than VBM4D). The simplicity of the NVCA filter and its low computational burden make this filter suitable for real-time video processing and its hardware implementation is ready to be included in future fluoroscopy devices, offering further lowering of patient’s X-ray dose.

Determination of 3D PSFs from computed tomography reconstructed x-ray images of spherical objects and the effects of sphere radii.

A method was developed to obtain three-dimensional (3D) point spread functions (PSFs) of reconstructed x-ray volumetric images using spheres of known diameters. The algorithm consists of a sphere localization step using template matching applied to the entire volume. Richardson Lucy (RL) deconvolution is used atypically to determine the PSF from the reconstructed x-ray image and a model of the sphere. The resulting PSF is arbitrary, that is, there are no assumptions of separability or symmetry. Oversampling is not used, and sample spacing matches the image. The effect of sphere radius on PSF estimate reproducibility is investigated. Phantoms were constructed by suspending five polytetrafluoroethylene (PTFE) spheres having known radii equal to 4.77, 7.95, 9.52, 12.68, and 19.53mm in an agar solution. The phantom included a 25μm steel wire to calculate a line spread function (LSF). The phantom was imaged and reconstructed with a Medtronic surgical O-Arm 23 times and a Toshiba Aquilion One computed tomography (CT) 20 times. A sharp reconstruction kernel exhibiting a nonmonotonic PSF was used with the Toshiba CT. PSFs and LSFs were computed for all of the images and repeated estimates were used to compute mean and standard deviation values for every point of the PSFs and LSFs. The PSFs from spheres were converted to LSFs and compared to the wire LSF. The standard deviations of the PSF estimates exhibit a decreasing trend as the sphere radius is increased. The PSF from the smallest 4.77mm sphere is the least reproducible. The normalized root mean square difference between the mean LSF derived from the 4.77mm radius sphere and the mean wire LSF is 2.0% for the O-arm and 1.2% for the CT. Richardson Lucy (RL) deconvolution provides a method to estimate generalized (no separability or other simplifying assumptions) 3D PSFs from spheres. X-ray noise in images acquired with typical clinical protocols cause noticeable variations in PSF estimates which can be mitigated by selecting larger spheres and combining PSF estimates from different images.

Automated MTF measurement in CT images with a simple wire phantom

Abstract This study developed a simple wire phantom and an algorithm to automatically measure the modulation transfer function (MTF) in computed tomography (CT) and implemented it to evaluate the effect of focal spot size and reconstruction filter type. The phantom consisted of a resin cylinder filled with water, with a tin wire of diameter 0.1 mm positioned along the center of the cylinder. The automated MTF algorithm used an axial image of the phantom and comprised several steps. The center position of a region of interest (ROI) was automatically determined at the center of the wire image. The pixels were then summed along the y-direction to obtain the profile of the pixel values at a point along the x-direction. Following this, both edges of the profile were made equal to zero. The profile curve was then normalized so that the total of all the data was equal to unity. The normalized profile curve is the line spread function (LSF), and the MTF curve was obtained by taking its Fourier transform. Our system (phantom and algorithm) is able to differentiate the MTFs of CT images from different focal sizes and reconstruction filter types.

The Effects of Contrast Medium on Food Viscosity and Muscle Activity of the Submental Muscle Group

A videofluoroscopic swallowing study (VFSS) is utilized for diagnosis of dysphagia or to determine dysphagia diets. For the evaluation of swallowing function via VFSS, contrast medium needs to be added to the food. The purpose of this study was to assess the effects of contrast medium on food viscosity and the muscle activity of the submental muscle group. Viscosity measurements were performed using a viscometer and a line spread test (LST), after adding contrast medium into water, yogurt, and porridge to 0%, 12.5%, 25.0%, and 37.5% v/v concentrations. Surface electromyography (sEMG) was performed on 20 healthy adults by attaching EMG electrodes to the submental muscle group. Diet consisted of non-contrast medium food and food containing 37.5% v/v contrast medium. There were significant differences in viscometer and LST results between non-contrast medium food and food with contrast medium (p < 0.001). There was a significant negative correlation between viscometer and LST outcomes (water r = - 0.889, p < 0.001; yogurt r = - 0.952, p < 0.001; porridge r = - 0.837, p < 0.001). Finally, there was a significant difference in muscle activity between non-contrast medium water (2.5 cc) and water containing contrast medium 37.5% v/v (2.5 cc) (p = 0.025). These findings suggest that, when performing VFSS, clinicians should consider changes in food viscosity due to contrast medium in order to provide accurate diagnoses and dysphagia diet plans.