Journal articles: 'Spot scan'

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KIM, DONG SOO, SUNG WOO BAE, and KYUNG HYUN CHOI. "APPLICATION AND PERFORMANCE EVALUATION FOR THE DMS SYSTEM IN THE SLS PROCESS." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1833–38. http://dx.doi.org/10.1142/s0217979208047493.

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A Solid Freeform Fabrication (SFF) system using Selective Laser Sintering (SLS) is currently recognized as a leading process and SLS extends the applications to machinery and automobiles due to the various materials employed. Especially, accuracy and processing time are very important factors when the desired shape is fabricated with Selective Laser Sintering (SLS), one of Solid Freeform Fabrication (SFF) system. In the convectional SLS process, laser spot size is fixed during laser exposing on the sliced figure. Therefore, it is difficult to accuracy and rapidly fabricates the desired shape. In this paper, to deal with those problems a SFF system having ability of changing spot size is developed. The system provides high accuracy and optimal processing time. Specifically, a variable beam expander is employed to adjust spot size for different figures on a sliced shape. Therefore, design and performance estimation of the SFF system employing a variable beam expander are achieved and the mechanism will be addressed to measure the real spot size generated from the variable beam expander. Also, the reduction of total processing time is an important issue in SFF system. A digital mirror system (DMS) is a system which scans the laser beam with different spot size. The spot size is selected based on the slicing section to decrease and accuracy of the process time and improve the processing efficiency. In this study, the optimal scan path generation for DMS will be addressed, and this development will improve the whole processing efficiency and accuracy through the scan efficiency by considering the existing scan path algorithm and heat energy distribution.

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Downing, K. "Spot-scan imaging in transmission electron microscopy." Science 251, no. 4989 (January 4, 1991): 53–59. http://dx.doi.org/10.1126/science.1846047.

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Downing, Kenneth H. "Defocus ramp correction in spot-scan imaging." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (August 1992): 130–31. http://dx.doi.org/10.1017/s0424820100121053.

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Three-dimensional structures of a number of samples have been determined by electron crystallography. The procedures used in this work include recording images of fairly large areas of a specimen at high tilt angles. There is then a large defocus ramp across the image, and parts of the image are far out of focus. In the regions where the defocus is large, the contrast transfer function (CTF) varies rapidly across the image, especially at high resolution. Not only is the CTF then difficult to determine with sufficient accuracy to correct properly, but the image contrast is reduced by envelope functions which tend toward a low value at high defocus.We have combined computer control of the electron microscope with spot-scan imaging in order to eliminate most of the defocus ramp and its effects in the images of tilted specimens. In recording the spot-scan image, the beam is scanned along rows that are parallel to the tilt axis, so that along each row of spots the focus is constant. Between scan rows, the objective lens current is changed to correct for the difference in specimen height from one scan to the next.

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Benner, G., J. Frey, and E. Weimer. "Slit scan illumination for dynamic focusing." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 356–57. http://dx.doi.org/10.1017/s0424820100086088.

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This mode describes a modification of the spot scan mode1 in which areas on a photographic plate are exposed one after the other using small illuminating spots. The spot scan mode in transmission electron microscopes (TEM) reduces specimen damage and specimen drift. In addition to this it allows dynamic focussing at high tilt angles of the specimen.High-resolution, 3-D specimen reconstruction and reflection electron imaging using specimen tilt angles of up to 90° require dynamic focussing rectangular to the tilt axis of the goniometer for imaging of off-axis specimen areas. A slit-type illumination of the specimen parallel to the goniometer tilt axis may provide a better solution for such types of problems.

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Ansari, Zahir Ahmed, Avnish Kumar, Rajeev Marathe, and MJ Nigam. "Spiral Scan Pattern Generation for Laser Spot Tracker." IFAC-PapersOnLine 49, no. 1 (2016): 112–17. http://dx.doi.org/10.1016/j.ifacol.2016.03.038.

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Singaporewalla, Reyaz M., Anuradha Negi, Dominique YB Seow, and Dinesh Chinchure. "An Unusual Cause of Hot Spot on Parathyroid Imaging." World Journal of Endocrine Surgery 8, no. 2 (2016): 164–67. http://dx.doi.org/10.5005/jp-journals-10002-1183.

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ABSTRACT Background and aim Radiological imaging is routinely used in patients with primary hyperparathyroidism to localize the abnormal adenoma and to plan surgical approach. We report an unusual cause of false-positive localization on parathyroid sestamibi scan, i.e., not previously described in the literature. Case report A 66-year-old man with primary hyperparathyroidism showed a discrete persistent focus in the left infraclavicular area during localization using sestamibi scan. Ultrasound of the neck was negative showing only small bilateral thyroid nodules. Single-photon emission and four-dimensional computed tomography (CT) scans showed an intense focus of the tracer uptake and a 1-cm lesion near the left subclavian vein (SCV), corresponding to the infraclavicular hot spot. Initial infraclavicular exploration showed the lesion to be a collapsible saccular varix of the left SCV. Bilateral neck exploration led to the discovery of the actual right parathyroid adenoma beneath an exophytic thyroid nodule. The patient made an uneventful recovery and remains normocalcemic at 1-year follow up. Conclusion and clinical significance Hot spot on parathyroid imaging outside the line of embryological descent should be interpreted with caution. Vascular retention of injected isotope within a saccular varix of the neck vein can give rise to falsepositive results on sestamibi scans. Bilateral neck exploration remains the “gold standard” procedure when localization scans either are negative or turn out to have false-positive findings. How to cite this article Singaporewalla RM, Negi A, Seow DYB, Chinchure D. An Unusual Cause of Hot Spot on Parathyroid Imaging. World J Endoc Surg 2016;8(2):164-167.

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Olson, N. H., U. Lücken, S. B. Walker, M. T. Otten, and T. S. Baker. "Cryoelectron microscopy and image reconstruction of spherical viruses with spot scan and FEG technologies." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 1086–87. http://dx.doi.org/10.1017/s0424820100141809.

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The field emission gun electron microscope (FEG) is a tool that has the potential to achieve near atomic resolution information of biological macromolecules. The FEG provides a beam with higher spatial and temporal coherence and a better phase contrast transfer function than do microscopes with either tungsten or LaB6 filaments. The FEG is also ideal for spot scan imaging applications because it can produce a small, coherent and very bright spot. In spot scan mode the specimen is exposed to an array of nonoverlapping spots rather man a flood beam. This significantly reduces beam-induced specimen drift.Frozen-hydrated samples of cowpea chlorotic mottle (CCMV, Fig. 1A) and cowpea severe mosaic virus (CPSMV, Fig. IB) were examined on a Philips CM12 transmission electron microscope equipped with a standard LaB6 gun and on a Philips CM200 equipped with a field emission gun, respectively. The CM12 was operated at 120kV and was externally controlled by means of a spot scan imaging program which produced a series of 250 nm diameter spots on Kodak SO-163 sheet film.

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Wang, Shi Gang, Yong Yan, and Feng Juan Wang. "Measured Scan Data Reduction Combination Algorithm Based on Scan Line." Applied Mechanics and Materials 651-653 (September 2014): 2335–38. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.2335.

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The 3D laser scanning technology is a hot spot in developed measuring in recent years. In the surface reconstruction of reverse engineering, the 3D laser scanning point cloud data is too large, and is not conducive to the computation, storage and surface reconstruction. After understanding the research status of the point cloud data processing streamline method at home and abroad, and through the analysis of minimum distance algorithm and the angle-chord height combined code method applicable to engineering characteristics, at the same time, the combination algorithm, which is based on the minimum distance algorithm and the angle-chord height combined code method, is proposed to simplify the point cloud data. The scanning point cloud is simplified by using matlab line by line.

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Durandet, Y., S. Sun, and M. Brandt. "Microstructure of Laser Treated ZE41A-T5 Magnesium Alloy." Materials Science Forum 654-656 (June 2010): 759–62. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.759.

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Modification of the microstructure of ZE41A-T5 magnesium alloy substrates was investigated by laser surface re-melting and solidification using a 2.5 kW Nd:YAG laser. The effects of laser power, high scan rate and beam configuration were examined. The microstructure of laser treated ZE41 consisted of small precipitates dispersed in a fine dendritic α-magnesium matrix at high scan rates. The redistribution of chemical elements depended mainly on the dwell time in the liquid stage. At high scan rates, long dwell times were achieved by splitting the laser beam into two spots trailing in the scan direction which resulted in a more homogenous distribution of Mg, Zn and Zr. Cracking due to thermal shrinkage during solidification was prevented by reducing the temperature of the melt pool. This was achieved by lowering the laser power, increasing the scan rate and laser spot size. Increasing the laser spot size in the scan direction was conducive to producing homogeneous microstructures without cracks.

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Allwright, Stephen J., and John H. Miller. "SUBPERIOSTEAL ABSCESS CAUSING A “COLD” SPOT ON BONE SCAN." Clinical Nuclear Medicine 13, Supplement (September 1988): P17. http://dx.doi.org/10.1097/00003072-198809001-00030.

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Downing, K. H. "Spot Scan Imaging and the Future of High Resolution." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 88–89. http://dx.doi.org/10.1017/s0424820100179191.

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Electron crystallographers who have been working on determination of protein structure have set a goal of obtaining image information to a resolution of about 3.5 Å, from specimens tilted up to 60 degrees. This information would allow the construction of a three-dimensional density map within which the path of the peptide chain could be followed and locations of side chains defined. The recent determination of an atomic model of the membrane protein bacteriorhodopsin (bR) from EM data (1) which was not as complete as we would like, used a good deal of other biochemical and biophysical data to constrain the model. In cases where this type of information is not as extensive as with bR, isotropic high-resolution data would be required. Significant advances in several different areas have brought us tantalizingly close to reaching our goal, but there are still improvements to be made.The essential limitations in obtaining high resolution data from proteins arise from the radiation sensitivity of the specimen, which severely limits the electron exposure that can be used in recording an image and thus limits the signal-to-noise ratio (SNR). Increasing both the electron dose, which is possible with cold specimens, and the area processed, which required implementation of significant computer software, have each given about a factor of three improvement in SNR. Still, with conventional imaging, a study by Henderson and Glaeser (2) revealed that the best images contained only a small fraction of the signal that would be present in a perfect image. Factors such as the envelope of the contrast transfer function and the modulation transfer function of the photographic film account for some loss of contrast, but the factor causing the most loss was found to be beam-induced specimen motion. This motion results from the stress which is produced by changes in bond structure during the course of radiation damage.

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Sherman, Michael B., Toshinori Soejima, Marin van Heel, and Wah Chiu. "Correlation averaging and structural changes in GP32*I crystal unit cells." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 106–7. http://dx.doi.org/10.1017/s0424820100168268.

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We compared correlation and Fourier averaging by analyzing 400 kV spot-scan electron images of iceembedded gp32*I crystals from a previous study using correlation averaging and multivariate statistical analysis (MSA). The set consisted of 9 spot-scan electron images (Fig. 1) from different micrographs. Unit cells of gp32*I crystal in each spot-scan image were located using cross-correlation map ofthe whole image with its central portion (an area of up to 10 unit cells). Each correlation peak in the map served as a center for picking up a patch of the same size as the reference used for mapcalculation. After averaging of the patches a new reference with improved signal-to-noise ratio was obtained and procedure was iterated several times using progressively smaller reference sizes. Final reference size was about 1-2 unit cells. This permitted us to follow local lattice variations. The technique does not use any assumption of crystallinity of the specimen and can be applied for highly distorted crystal lattices. Each spot-scan image was processed independently of the others. After the iterativeprocedure a final set of averaged images was obtained and structure factor amplitudes and phases were calculated from them using standard crystallographic procedures followed by merging all the spectra. Using the set of structure factors a projection map was generated which looked very similar to the 4 Å resolution map obtained using Fourier averaging technique (Fig. 2).

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RAMOS, MAX ROGÉRIO FREITAS, PEDRO FILGUEIRAS HIDALGO, DIOGO FAGUNDES, and YONDER ARCHANJO CHING SAN JUNIOR. "BARE SPOT LOCATION IN GLENOID CAVITY: COMPARISON BETWEEN ARTHROSCOPY AND CT SCAN." Acta Ortopédica Brasileira 28, no. 5 (October 2020): 243–46. http://dx.doi.org/10.1590/1413-785220202805232045.

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ABSTRACT Objective: To assess whether Bare Spot is previously displaced by proportion (MEASURE BP-A × 1.25/MEASURE BP-P = 1). Methods: 35 patients with surgical indication for rotator cuff injury repair were evaluated. The distances from the Bare Spot to the anterior edge of the glenoid cavity (BS-A) and to the posterior edge (BS-P) were measured by arthroscopy and computed tomography with three-dimensional reconstruction of the scapula. Results: The distance from the Bare Spot to the anterior border (BS-A tc) was 11.6 mm with a median 12 mm; The distance to the posterior border (BS-P tc) was on average 15.5 mm with a median 15 mm. The distances from BS to anterior cavity edge measured by arthroscopy were on average (BS-A video) 12.25 mm with a median of 12 mm, and from BS to posterior edge (BS-P video) 16.25 mm on average with median 16 mm (p < 0.005). Conclusion: Bare Spot is displaced anteriorly at a proportion of 40% of the anterior margin and 60% of the posterior margin. Level of Evidence II - Development of diagnostic criteria on consecutive patients (with universally applied reference “gold standard”).

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Koster, A. J., J. Walz, U. Ziese, A. Stoschek, R. Hegerl, D. Typke, J. Kleinz, and W. Baumeister. "Automated electron tomography and CCD spot-scan imaging of biological macromolecules." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 120–21. http://dx.doi.org/10.1017/s0424820100168335.

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Computer control of a transmission electron microscope (TEM) and digital recording of images have shown to be useful tools in recording 2D data sets of macromolecules and larger cellular structures with accurately defined imaging conditions.3D structure of individual molecules can be obtained by electron tomography. The method requires that projection data are collected over a large range of specimen tilts. With automated electron tomography images are recorded in digital format, and lateral specimen displacement together with focus changes are automatically compensated for. Typically, with our experimental set-up, we collect 75 projections of negatively stained preparations over ±75° and 30 projections of ice-embedded molecules over ±60° with a total dose of 20-50 e/Å2.By using the spot-scan imaging mode beam-induced movements of ice-embedded specimens are greatly reduced, thus largely avoiding the loss of resolution associated with specimen instability. With CCD spot-scan imaging the size of the spot is matched to the CCD chip (Fig. 1).

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LIM, J. K., J. B. ROSENZWEIG, S. G. ANDERSON, and A. M. TREMAINE. "A HIGH-DENSITY ELECTRON BEAM AND QUAD-SCAN MEASUREMENTS AT PLEIADES THOMSON X-RAY SOURCE." International Journal of Modern Physics A 22, no. 23 (September 20, 2007): 4317–23. http://dx.doi.org/10.1142/s0217751x07037858.

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A recent development of the photo-cathode injector technology has greatly enhanced the beam quality necessary for the creation of high density/high brightness electron beam sources. In the Thomson backscattering x-ray experiment, there is an immense need for under 20 micron electron beam spot at the interaction point with a high-intensity laser in order to produce a large x-ray flux. This has been demonstrated successfully at PLEIADES in Lawrence Livermore National Laboratory. For this Thomson backscattering experiment, we employed an asymmetric triplet, high remanence permanent-magnet quads to produce smaller electron beams. Utilizing highly efficient optical transition radiation (OTR) beam spot imaging technique and varying electron focal spot sizes enabled a quadrupole scan at the interaction zone. Comparisons between Twiss parameters obtained upstream to those parameter values deduced from PMQ scan will be presented in this report.

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Downing, Kenneth H. "Automatic focus correction for spot-scan imaging of tilted specimens." Ultramicroscopy 46, no. 1-4 (October 1992): 199–206. http://dx.doi.org/10.1016/0304-3991(92)90015-c.

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Liu, Yali, Yulong Pan, Haishan Chen, Wenzhe Wang, Tong An, and Xu Chen. "Research on quality inspection model of spot welding of equal-thickness three-layer sheets based on ultrasonic A-scan." Journal of Physics: Conference Series 2246, no. 1 (April 1, 2022): 012083. http://dx.doi.org/10.1088/1742-6596/2246/1/012083.

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Abstract To judge the spot welding quality automatically and effectively, this thesis uses the conventional ultrasonic A-scanning to study the mathematical model of nugget diameter for equal-thickness three-layer sheets. The finite element simulation model of the spot welding ultrasonic nondestructive (NDT) testing for equal-thickness three-layer low carbon sheets is established. The calculated values of the nugget diameter between different laminates are studied. Finally, the experiment of the spot welding ultrasonic nondestructive testing is carried out. This thesis verifies the correctness of the finite element simulation and the mathematical calculation model. The research results are of great significance to ultrasonic automatic inspection technology of spot welding.

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Kindness, Andrew, Chandra N. Sekaran, and Jörg Feldmann. "Two-Dimensional Mapping of Copper and Zinc in Liver Sections by Laser Ablation–Inductively Coupled Plasma Mass Spectrometry." Clinical Chemistry 49, no. 11 (November 1, 2003): 1916–23. http://dx.doi.org/10.1373/clinchem.2003.022046.

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Abstract Background: Metals are not homogeneously distributed in organ tissues. Although most mapping techniques, such as histologic staining methods, have been developed for element imaging on a subcellular level, many suffer from either low precision or poor detection limits. Therefore, small variations in elemental distribution cannot be identified. We developed a method for two-dimensional mapping of trace elements to identify the influence of metabolic zonation by the liver on trace element distribution. Methods: A prepared homogeneous Certified Reference Material (CRM; LGC 7112, pig liver) was used to characterize the laser ablation–inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-MS) in terms of precision. Different isotopes for copper and zinc were monitored, and the use of carbon as an internal standard was investigated to correct for differences in ablation efficiency to identify the most precise mapping technique for liver samples. Results: For the homogeneous CRM, the reproducibility of the copper and zinc signals was ∼3–24% depending on spot size and number of pulses. When carbon was used as an internal standard, the reproducibility was improved significantly. Line scan signals over a length of 1.5 mm were more precise [relative SD (RSD), 1.6–6.1% for copper (63Cu, 65Cu) and zinc (64Zn, 66Zn) depending on the spot size, the scanning speed, and the element]. Thin section of sheep liver achieved precisions of 27–59% (raster scan) and 9–47% (line scan) RSD for copper, whereas the precision for zinc was significantly better: 8–18% (raster scan) and 4–21% (line scan) RSD. Long line scans and two-dimensional element maps of the thin sections revealed the zonation of copper in sheep liver containing extremely low copper concentrations. Conclusion: Elemental mapping of trace elements generated by LA-ICP-MS can be very precise so that small changes in the elemental concentration in the tissue can be detected and nonuniform spatial distribution of the elements in tissues can be established.

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Thuman-Commike, Pamela A., and Wah Chiu. "Automatic Detection of Spherical Particles from Spot-Scan Electron Microscopy Images." Microscopy and Microanalysis 1, no. 5 (October 1995): 191–201. http://dx.doi.org/10.1017/s1431927695111915.

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In this article we present a method to identify and extract spherical particle images from noisy spot-scan and flood beam electron microscopy images. We use a template matching algorithm with additional image preprocessing operations to allow consistent particle selection in spot-scan and other highly spatially varying images. In addition, this algorithm incorporates an automated image-cutting and edge-sewing mechanism that allows efficient particle selection despite the large size of electron microscopy images. We have tested this template matching algorithm on various spherical virus particle images with a large range of defocus values and have found that the particles are consistently selected in an accurately centered manner. In addition, this method is able to extract spherical virus particles from 400-kV electron microscopy images with defocus values of less than 1.0 μm underfocus where the particles are not readily visible to the human eye.

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Fakhri, Asif A., and Sabah Iqbal. "2226 Hot Spot Sign on Tc-99m DISIDA Nuclear Hepatobiliary Scan." American Journal of Gastroenterology 114, no. 1 (October 2019): S1246—S1247. http://dx.doi.org/10.14309/01.ajg.0000598436.88405.5a.

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Zhong, Li, Xiaoyan Li, Min Zhu, Zhuoyue Hu, and Fansheng Chen. "Improved Intra-Pixel Sensitivity Characterization Based on Diffusion and Coupling Model for Infrared Focal Plane Array Photodetector." Sensors 21, no. 24 (December 8, 2021): 8195. http://dx.doi.org/10.3390/s21248195.

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The high-precision characterization of the intra-pixel sensitivity (IPS) for infrared focal plane array (FPA) photodetector is of great significance to high-precision photometry and astrometry in astronomy, as well as target tracking in under-sampled remote sensing images. The discrete sub-pixel response (DSPR) model and fill factor model have been used for IPS characterization in some studies. However, these models are incomplete and lack the description of physical process of charge diffusion and capacitance coupling, leading to the inaccuracy of IPS characterization. In this paper, we propose an improved IPS characterization method based on the diffusion and coupling physical (DCP) model for infrared FPA photodetector, which considering the processes of generation and collection of the charge, can improve the accuracy of IPS characterization. The IPS model can be obtained by convolving the ideal rectangular response function with the charge diffusion function and the capacitive coupling function. Then, the IPS model is convolved with the beam spot profile to obtain the beam spot scanning response model. Finally, we calculate the parameters of IPS by fitting the beam spot scanning response map with the proposed DCP model based on the Trust-Region-Reflective algorithm. Simulated results show that when using a 3 μm beam spot to scan, the error of IPS characterization based on DCP model is 0.63%, which is better than that of DSPR model’s 3.70%. Experimental results show that the fitting error of the beam spot scan response model based on DCP model is 4.29%, which is better than that of DSPR model’s 8.31%.

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SLAVIN, JAMES D., ZAHIDA YOOSUFANI, and RICHARD P. SPENCER. "Bone Scan Cold Spot from Separation of Osseous Fragments in Pathologic Fracture." Clinical Nuclear Medicine 12, no. 8 (August 1987): 659–60. http://dx.doi.org/10.1097/00003072-198708000-00020.

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Cheki, Mohsen, Tohid Dehghani, Mansoureh Eftekhari, and Masood Moslehi. "Focal hot spot induced by a central subclavian line on bone scan." Advanced Biomedical Research 3, no. 1 (2014): 230. http://dx.doi.org/10.4103/2277-9175.145723.

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Davis, A. P., and A. M. White. "Modelling of two-dimensional photodiode arrays by random walk spot-scan simulation." Infrared Physics 28, no. 6 (November 1988): 375–82. http://dx.doi.org/10.1016/0020-0891(88)90063-2.

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Bullough, P. A., and P. A. Tulloch. "Spot-scan imaging of microcrystals of an influenza neuraminidase-antibody fragment complex." Ultramicroscopy 35, no. 2 (February 1991): 131–43. http://dx.doi.org/10.1016/0304-3991(91)90097-p.

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Yamashita, Keitaro, Kunio Hirata, Yoshiaki Kawano, Go Ueno, Kazuya Hasegawa, Takashi Kumasaka, and Masaki Yamamoto. "SHIKA: a fast and accurate spot finder for raster scan on microfocus beamlines." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C352. http://dx.doi.org/10.1107/s2053273314096478.

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On BL32XU, a microfocus beamline at SPring-8, oscillation data are collected with typical horizontal beam size of 1 μm. Hence it requires very accurate crystal centering, which is difficult especially for invisible crystals e.g. LCP crystals. Therefore, we perform raster diffraction scan to find crystal positions based on their diffractivity using low-dose exposure. It had been time consuming process due to two reasons; i) slow readout time of CCD, ii) manual inspection of hundreds of diffraction images. To tackle this problem, we installed new fast-readout CCD detector, MX225HS (Rayonix, L.L.C.), and developed support tool for raster scan based crystal centering. The tool visually shows possible crystal position on 2D map based on spot populations, and therefore it is named SHIKA (Spot-wo Hirotte Ichiwo Kimeru Application; a Japanese abbreviation which means the application for crystal positioning by picking up spots). SHIKA automatically detects new images when raster scan started and finishes just after raster scan ends. On GUI, user can find and pass the crystal position information to KUMA (a tool suggesting helical data collection strategy with predicted radiation damage) to start data collection immediately. User can also see picked spots on diffraction images with GUI. SHIKA has been developed based on DISTL [1] and modified to be faster and more accurate, especially for LCP crystal which is an important target on BL32XU. SHIKA picks up spots after subtracting smoothed pseudo-background which is a key for better separation of spots and ring-like diffuse background of lipids. Smoothing is time-consuming, but SHIKA now uses GPUs for almost all process including high-speed median filter [2] so that it can be done within ~100 msec. Further development is under way for faster processing. Now SHIKA can be also used on BL41XU, a high flux beamline at SPring-8 with some adjustment for PILATUS3 (Detectris Ltd.) detector.

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Cipiccia, Silvia, Francesco Brun, Vittorio Di Trapani, Christoph Rau, and Darren J. Batey. "Dual energy X-ray beam ptycho-fluorescence imaging." Journal of Synchrotron Radiation 28, no. 6 (October 5, 2021): 1916–20. http://dx.doi.org/10.1107/s1600577521008675.

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X-ray ptychography and X-ray fluorescence are complementary nanoscale imaging techniques, providing structural and elemental information, respectively. Both methods acquire data by scanning a localized beam across the sample. X-ray ptychography processes the transmission signal of a coherent illumination interacting with the sample, to produce images with a resolution finer than the illumination spot and step size. By enlarging both the spot and the step size, the technique can cover extended regions efficiently. X-ray fluorescence records the emitted spectra as the sample is scanned through the localized beam and its spatial resolution is limited by the spot and step size. The requisites for fast ptychography and high-resolution fluorescence appear incompatible. Here, a novel scheme that mitigates the difference in requirements is proposed. The method makes use of two probes of different sizes at the sample, generated by using two different energies for the probes and chromatic focusing optics. The different probe sizes allow to reduce the number of acquisition steps for the joint fluorescence–ptychography scan compared with a standard single beam scan, while imaging the same field of view. The new method is demonstrated experimentally using two undulator harmonics, a Fresnel zone plate and an energy discriminating photon counting detector.

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Cipiccia, Silvia, Francesco Brun, Vittorio Di Trapani, Christoph Rau, and Darren J. Batey. "Dual energy X-ray beam ptycho-fluorescence imaging." Journal of Synchrotron Radiation 28, no. 6 (October 5, 2021): 1916–20. http://dx.doi.org/10.1107/s1600577521008675.

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X-ray ptychography and X-ray fluorescence are complementary nanoscale imaging techniques, providing structural and elemental information, respectively. Both methods acquire data by scanning a localized beam across the sample. X-ray ptychography processes the transmission signal of a coherent illumination interacting with the sample, to produce images with a resolution finer than the illumination spot and step size. By enlarging both the spot and the step size, the technique can cover extended regions efficiently. X-ray fluorescence records the emitted spectra as the sample is scanned through the localized beam and its spatial resolution is limited by the spot and step size. The requisites for fast ptychography and high-resolution fluorescence appear incompatible. Here, a novel scheme that mitigates the difference in requirements is proposed. The method makes use of two probes of different sizes at the sample, generated by using two different energies for the probes and chromatic focusing optics. The different probe sizes allow to reduce the number of acquisition steps for the joint fluorescence–ptychography scan compared with a standard single beam scan, while imaging the same field of view. The new method is demonstrated experimentally using two undulator harmonics, a Fresnel zone plate and an energy discriminating photon counting detector.

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Kumar, Jagadeesha, Abdul Hadi G. Abulrub, Alex Attridge, and Mark A. Williams. "Effect of X-Ray Computed Tomography Scanning Parameters on the Estimated Porosity of Foam Specimens." Applied Mechanics and Materials 110-116 (October 2011): 808–15. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.808.

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X-Ray Computed Tomography (CT) scanning is an effective method for estimating the porosity of various engineering materials and biomedical specimens such as tissue scaffolds and bones. However, the scanning and analysis parameters play a significant role in the accuracy of the porosity value determined from CT scan. This paper presents details of an investigation carried out to understand the effect of system parameters, namely the voxel size, X-ray focal spot size and segmentation threshold, on the estimated porosity by taking an example of safety-critical foam used for impact protection applications. Different voxel resolutions and focal spot sizes are selected in a total of 12 scanning tests and the effect of segmentation threshold is analyzed on each of these tests. The study indicates that the obtained porosity value is greatly influenced by the choice of voxel size at larger spot sizes and less influenced at smaller spot sizes. The threshold also has significant effect on the porosity value, especially at larger voxel sizes.

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Duisenberg, Albert J. M., Rob W. W. Hooft, Antoine M. M. Schreurs, and Jan Kroon. "Accurate cells from area-detector images." Journal of Applied Crystallography 33, no. 3 (June 1, 2000): 893–98. http://dx.doi.org/10.1107/s0021889800002363.

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A procedure is described, for an Eulerian or Kappa goniostat, to determine the exact spindle value φ at the moment of impact of a reflection on an area detector; such information is essential for the calculation of accurate reflection vectors and, eventually, the unit-cell and lattice orientation. The method is based on a comparison of reflection impact coordinates on two related images. One image is obtained by spindle rotation over a few degrees (`φ scan') and the other by the same φ rotation, but with a superposed rotation (χ) perpendicular to the first (`φ/χ scan'). In both cases, the spindle is kept perpendicular to the primary beam,i.e.ω = 0 or 180°. Therefore, on the second image, exactly the same reflections as on the first will appear, but on a different spot on the detector. From the tangential separation between corresponding reflection impacts, the moment of impact (φ value) is calculated. The method is especially useful in small-molecule work, where rather wide scans are required for a reasonable number of reflections in one image. It is shown that for our purpose the Eulerian φ/χ scan can be simulated practically exactly by simultaneous uniform rotations of the axes ωK, κ and φKof the Kappa goniostat.

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Lin, Po-Hung, Hung-Jen Chen, and Zhi-Qian Wang. "Visual Performance Assessment of Videos—A Case Study of the Game “Spot the Difference”." Applied Sciences 11, no. 16 (August 19, 2021): 7628. http://dx.doi.org/10.3390/app11167628.

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“Spot the Difference” is a well-known game where players must find subtle differences between two almost identical pictures. If “Spot the Difference” is designed for videos, what is the difference between videos and pictures? If the performance of videos is measured by an eye tracker, what scan paths will be conducted? In this study, we explored this game using a video to conduct a visual performance evaluation. Twenty-five subjects were recruited in a full-factorial experiment to investigate the effect of background (with background, without background), video type (animation, text), and arrangement (left-to-right, top-to-bottom) on searching, eye tracking performance, and visual fatigue. The results showed that the video type had a significant effect on the accuracy and subjective visual fatigue, with the accuracy and subjective visual fatigue for animation being better than for text. The results also indicated that the arrangement had a significant effect on the number of fixations, where top-to-bottom arrangement brought a higher number of fixations. The background had a significant effect on accuracy and subjective visual fatigue, where the accuracy and subjective visual fatigue without a background was better than with a background. For the analysis of the scan path, a denser scan path was found in text than in animation, in top-to-bottom arrangement than in left-to-right arrangement, and without a background than with a background. In the future, game manufacturers should use the results of this research to design different “Spot the Difference” videos. When designing a simple game, an animation without a background and involving a left-to-right arrangement was recommended. When designing a difficult game, the opposite settings should be used.

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Li, Kaile. "Imaging investigation of small motion target for lung stereotactic body radiotherapy (SBRT)." International Journal of Radiology & Radiation Therapy 9, no. 3 (August 10, 2022): 89–91. http://dx.doi.org/10.15406/ijrrt.2022.09.00329.

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Purpose: Motion management is important in lung tumor SBRT. Small target four-dimensional computed tomography (4DCT) imaging could give significant target motion information. In this study, Quality of 4DCT for small target was investigated to provide information for treatment planning in SBRT of small target, which is in favor of magnifying the target margin characteristics during 4DCT scan. Method and Materials: A Real Time Position Management (RPM) phantom from Varian Medical System and 6 CT-spot pellets from Beekley Medical were employed for this study. Each pellet was equivalent to a 4mm diameter ball. The CT spot pellets were attached to the RPM phantom. Two pellet set planes formed 8cm distance and generated two speeds which were 0.2cm and 0.4mm per second given a period with 5.0 seconds. With a GE LightSpeedTM RT CT scanner, the phantom was executed with helical scan with 1.25mm slice thickness with and without motion. Then a 4D CT scan in axial cine mode was carried on at the same phantom. The image exams were exported the GE Advantage Workstation for process. The exams were reviewed and sorted into 10 phases retrospectively. The 0% phase image set, 50% phase image set, maximum intensity projection (MIP) image set, and average intensity projection (Ave-IP) image set were exported to the Eclipse treatment planning system for analysis. In image sets, multi-dimensional variables such as center coordinate of pellets, distance between pellets, and volume of the pellets were used for analysis. Results: At 350 HU window width and 40HU window level, image sets from helical scan for the static phantom is used as reference, comparing to helical scan from moving phantom, retrospective MIP, average intensity projection, 0% phase and 50% phase, for pellets moving at 0.4 cm per second, the average coordinate deviation are 0.49cm, 0.22cm, 0.19cm, 0.59cm and 0.06cm with standard deviation 0.83cm, 0.29cm, 0.32cm, 0.69cm, and 0.07cm, the percentage distance differences are 10.2%, 3.3%, 7.3%, 0.1%, and 0.1% with standard deviation of 13.2%, 4.4%, 9.6%, 0.1%, and 0.1%. and the percentage volumes changes are 17.4%, 171.5%, 18.4%, 14.2% and 7.8% with standard deviation at 25.4%, 201.8%, 23.7%, 19.85% and 10%. Conclusions: A simple and sensitive 4DCT quality assurance method was developed by combining Varian RPM phantom and CT-spot pellets from Beekley Medical and it shows that the 50% phase image set is better for SBRT planning. Further study will include dosimetric effect on the small target moving in different directions.

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Chiu, Wah, Michael Sherman, and Jaap Brink. "Spot-scan imaging of ice-embedded catalase crystal on a slow-scan CCD camera in a 400-kV electron cryomicroscope." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 98–99. http://dx.doi.org/10.1017/s0424820100168220.

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In protein electron crystallography, both low dose electron diffraction patterns and images are needed to provide accurate amplitudes and phases respectively for a 3-dimensional reconstruction. We have demonstrated that the Gatan 1024x1024 model 679 slow-scan CCD camera is useful to record electron diffraction intensities of glucose-embedded crotoxin complex crystal to 3 Å resolution. The quality of the electron diffraction intensities is high on the basis of the measured intensity equivalence ofthe Friedel-related reflections. Moreover, the number of patterns recorded from a single crystal can be as high as 120 under the constraints of radiation damage and electron statistics for the reflections in each pattern.A limitation of the slow-scan CCD camera for recording electron images of protein crystal arises from the relatively large pixel size, i.e. 24 μm (provided by Gatan). The modulation transfer function of our camera with a P43 scintillator has been determined for 400 keV electrons and shows an amplitude fall-off to 0.25 at 1/60 μm−1.

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Sherman, M. B., and W. Chiu. "Reliability of phases retrieved from 400‐kV spot‐scan images of purple membranes acquired on a slow‐scan CCD camera." Journal of Microscopy 188, no. 3 (December 1997): 285–89. http://dx.doi.org/10.1046/j.1365-2818.1997.2450803.x.

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Takai, Michikatsu, Hans Blattmann, and Eros Pedroni. "An intercomparison of two dynamic treatment techniques, ring scan and spot scan, for head and neck tumors with the piotron." International Journal of Radiation Oncology*Biology*Physics 14, no. 5 (May 1988): 1025–31. http://dx.doi.org/10.1016/0360-3016(88)90028-4.

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Klemm, W. R. "God Spots in the Brain: Nine Categories of Unasked, Unanswered Questions." Religions 11, no. 9 (September 14, 2020): 468. http://dx.doi.org/10.3390/rel11090468.

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Neurotheology is an emerging academic discipline that examines mind-brain relationships in terms of the inter-relatedness of neuroscience, spirituality, and religion. Neurotheology originated from brain-scan studies that revealed specific correlations between certain religious thoughts and localized activated brain areas known as “God Spots.” This relatively young scholarly discipline lacks clear consensus on its definition, ideology, purpose, or prospects for future research. Of special interest is the consideration of the next steps using brain scans to develop this field of research. This review proposes nine categories of future research that could build on the foundation laid by the prior discoveries of God Spots. Specifically, this analysis identifies some sparsely addressed issues that could be usefully explored with new kinds of brain-scan studies: neural network operations, the cognitive neuroscience of prayer, biology of belief, measures of religiosity, role of the self, learning and memory, religious and secular cognitive commonalities, static and functional anatomy, and recruitment of neural processing circuitry. God Spot research is poised to move beyond observation to robust hypothesis generation and testing.

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Rajagopal, Sangeetha, Nivean Madhivanan, Lakshmi Mayilvakanam, and Pratheebadevi Nivean. "Choroidal Detachment Following Multi-spot Double Frequency Nd-YAG Retinal Photocoagulation – A Case Report." Journal of Lasers in Medical Sciences 11, no. 3 (June 21, 2020): 345–47. http://dx.doi.org/10.34172/jlms.2020.55.

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Introduction: Panretinal photocoagulation (PRP) remains the gold standard treatment for severe non-proliferative and proliferative diabetic retinopathy (PDR), as it reduces the risk of severe visual loss by more than 50%. In the conventional single-spot laser, the procedure involves the application of moderate-intensity burns of 200-500 microns, placed one spot-size apart to achieve a total of 1200-2000 applications in 2 or 3 sessions. The more advanced retina lasers like the Pattern Scan Laser (PASCAL) and the VITRA multi-spot laser are 532 nm frequency-doubled (Nd: YAG) solid-state lasers. These modern lasers enable the application of multiple laser burns in a rapid pre-determined sequence with reduced pulse duration (10-20 ms) to facilitate the PRP to be completed in a single sitting with lesser collateral tissue damage. Case Report: Though multi-spot lasers have significantly reduced the adverse events when compared with the conventional single-spot lasers, we report a case of rare adverse events (serous choroidal detachment) following PRP with the VITRA multi-spot double frequency NdYAG (532 nm) laser. Conclusion: Most of the serious choroidal detachments following PRP are self-limiting. We recommend complete retinal evaluation post laser procedure even with modern multisport laser to look for such adverse events.

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O'Connor, P. "Spot scan probe of lateral field effects in a thick fully-depleted CCD." Journal of Instrumentation 9, no. 03 (March 21, 2014): C03033. http://dx.doi.org/10.1088/1748-0221/9/03/c03033.

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Liang, Yiyong. "Dynamic scan detection of focal spot on nonplanar surfaces: theoretical analysis and realization." Optical Engineering 50, no. 7 (July 1, 2011): 073601. http://dx.doi.org/10.1117/1.3597327.

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Jakana, J., M. F. Schmid, P. Matsudaira, and W. Chiu. "High resolution spot scan imaging of frozen, hydrated actin bundles with 400kV electrons." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (August 1992): 512–13. http://dx.doi.org/10.1017/s0424820100122964.

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Actin is a protein found in all eukaryotic cells. In its polymerized form, the cells use it for motility, cytokinesis and for cytoskeletal support. An example of this latter class is the actin bundle in the acrosomal process from the Limulus sperm. The different functions actin performs seem to arise from its interaction with the actin binding proteins. A 3-dimensional structure of this macromolecular assembly is essential to provide a structural basis for understanding this interaction in relationship to its development and functions.

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PETKAR, S. "Disappearing hot spot on an indium 111 white cell scan: A case report." Journal of Nuclear Cardiology 15, no. 1 (January 2008): e1-e5. http://dx.doi.org/10.1016/j.nuclcard.2007.11.012.

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Thornton, M., L. Han, and M. Shergold. "Progress in NDT of resistance spot welding of aluminium using ultrasonic C-scan." NDT & E International 48 (June 2012): 30–38. http://dx.doi.org/10.1016/j.ndteint.2012.02.005.

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Wang, Jian Lai, Jian Cao, Qian Kai Lin, Hui Feng, and Hai Hua Shen. "Study on Numerical Simulation of Laser Quenching Based on ANSYS." Advanced Materials Research 538-541 (June 2012): 1862–65. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1862.

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In this paper, a temperature field model of 45 steel shafts during the laser quenching was built and simulated by using ANSYS software. Its surface temperature distribution of the shaft during the laser beams scanning was simulated. Their effects of different laser power, laser beams spot size and scan speed on part’s quenching performance were analyzed.

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Mahboubkhah, Mehran, Mohammad Aliakbari, and Colin Burvill. "An investigation on measurement accuracy of digitizing methods in turbine blade reverse engineering." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, no. 9 (October 24, 2016): 1653–71. http://dx.doi.org/10.1177/0954405416673681.

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Measurement and quality control of turbine blades is critical to the successful operation of power plants. It has a key role in manufacturing and reverse engineering. Novel technologies continue to be developed to measure parts with complex geometries, such as turbine blades. Digitizing techniques, using both contact and noncontact methods, are used. Selecting the most appropriate digitizing method for a turbine blade requires consideration of the measuring performance of the alternative methods, including criteria such as accuracy, speed and cost. This study seeks to evaluate the practical accuracy and efficiency of various contact and noncontact digitizing methods through measurement and associated quality control of a complex part, that is, a turbine blade airfoil. Four popular technologies, using distinct underlying measurement methods, were chosen to measure a Frame 5 gas turbine blade, namely, a touch trigger probe mounted on a Zeiss coordinate measuring machine, a touch scanning probe and a spot laser probe separately mounted on Renishaw coordinate measuring machine and a linear laser system from ZScanner. The measured point cloud resulting from each method was then used to reconstruct three-dimensional computer-aided design models of the blade. The accuracy of each measuring system was evaluated against the original blade. The evaluation incorporated a comparative study of design parameters derived from the point cloud and reconstructed surfaces associated with each measurement method. The maximum error of point clouds were −123, 2530 and 2173 µm for the ZScanner linear laser, Renishaw spot laser and Renishaw touch scan, respectively. These measured errors indicated higher accuracy from linear laser method than spot laser scanning and touch scanning methods. Furthermore, the achieved standard deviations of 42, 170 and 269 µm for point clouds of ZScanner linear laser, Renishaw spot laser and Renishaw touch scan, respectively, showed that the manufacturer reported that information cannot be always reliable.

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Storey, Michael A., Owen F. Price, Ross A. Bradstock, and Jason J. Sharples. "Analysis of Variation in Distance, Number, and Distribution of Spotting in Southeast Australian Wildfires." Fire 3, no. 2 (April 28, 2020): 10. http://dx.doi.org/10.3390/fire3020010.

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Spotting during wildfires can significantly influence the way wildfires spread and reduce the chances of successful containment by fire crews. However, there is little published empirical evidence of the phenomenon. In this study, we have analysed spotting patterns observed from 251 wildfires from a database of over 8000 aerial line scan images capturing active wildfire across mainland southeast Australia between 2002 and 2018. The images were used to measure spot fire numbers, number of “long-distance” spot fires (> 500 m), and maximum spotting distance. We describe three types of spotting distance distributions, compare patterns among different regions of southeast Australia, and associate these with broad measures of rainfall, elevation, and fuel type. We found a relatively high correlation between spotting distance and numbers; however, there were also several cases of wildfires with low spot fire numbers producing very long-distance spot fires. Most long-distance spotting was associated with a “multi-modal” distribution type, where high numbers of spot fires ignite close to the source fire and isolated or small clumps of spot fires ignite at longer distances. The multi-modal distribution suggests that current models of spotting distance, which typically follow an exponential-shaped distribution, could underestimate long-distance spotting. We also found considerable regional variation in spotting phenomena that may be associated with significant variation in rainfall, topographic ruggedness, and fuel descriptors. East Victoria was the most spot-fire-prone of the regions, particularly in terms of long-distance spotting.

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Ukar, Eneko, I. Tabernero, F. Liebana, I. Saitua, R. Villaseca, and J. Sobrado. "Parameter Study on Laser Surface Finishing with 2D Scan Head." Materials Science Forum 713 (February 2012): 109–14. http://dx.doi.org/10.4028/www.scientific.net/msf.713.109.

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In recent years laser polishing is becoming an alternative for automated surface finishing of dies and molds. This process involves melting and subsequent solidification of the material. Depending on the initial topography, the energy density necessary to reduce surface asperities can cause excessive heat damage, and thus, limit the applicability of the process. The work presented here focuses on the use of a high quality laser beam, with a spot diameter below 50 microns driven by a 2D scanner for processing of materials typically used in dies and mold manufacturing. So, the highly focused beam ensures minimal thermal damage, and the scan head allows high productivity rates. A new processing strategy based on two stages surface processing was developed to process topographies with strong directionality.

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Enoch, S., and S. D. Blair. "Exclusion of deep vein thrombosis by measuring spot skin temperatures using a hand-held thermo-comparator." Phlebology: The Journal of Venous Disease 18, no. 4 (December 1, 2003): 187–91. http://dx.doi.org/10.1258/026835503322598009.

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Objectives: Thermograms have shown that deep vein thrombosis (DVT) causes an increase in temperature in the leg. We have studied for the first time, the viability of measuring spot skin temperatures using a hand-held instrument called a thermo-comparator as an inexpensive, simple and reliable method of excluding the diagnosis of DVT. Methods: A total of 33 patients with suspected DVT had spot skin temperatures taken on specified areas of each leg using the instrument. The results were compared with duplex scans of the patient and with venography in some patients. Results: There was a mean temperature gradient of 3.38°C down each normal leg. All 10 patients with DVT confirmed by duplex scan or venogram also had raised temperatures compared with surrounding areas, without the normal temperature gradient down the leg (true positive, 100%). This instrument did not have any false negatives and achieved 100% sensitivity and 100% negative predictive value. Conclusions: The thermo-comparator excluded a diagnosis of DVT in 39% of patients and has the potential for use in primary care as a screening tool to reduce the number of patients sent to hospital unnecessarily.

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Liu, Jing, Guocheng Xu, Desheng Xu, Guanghao Zhou, and Qiuyue Fan. "Ultrasonic C-scan detection for stainless steel spot welding based on wavelet package analysis." Journal of Wuhan University of Technology-Mater. Sci. Ed. 30, no. 3 (June 2015): 580–85. http://dx.doi.org/10.1007/s11595-015-1192-8.

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Bullough, Per, and Richard Henderson. "Use of spot-scan procedure for recording low-dose micrographs of beam-sensitive specimens." Ultramicroscopy 21, no. 3 (January 1987): 223–30. http://dx.doi.org/10.1016/0304-3991(87)90147-1.

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Stuchinsky, Victor, and Alekcey Vishnyakov. "Fine structure of spatial diode photoresponse profiles measured while scanning a narrow strip-shaped illumination spot with FPA diode." Applied Physics, no. 3 (July 28, 2021): 47–53. http://dx.doi.org/10.51368/1996-0948-2021-3-47-53.

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The three-dimensional Monte Carlo simulation of charge-carrier diffusion in a mercury-cadmium-tellurium based focal plane array (FPA) was used to calculate the spatial diode photoresponse profiles measured while scanning a narrow strip-shaped illumination spot with a selected FPA diode in the limit of largest and lowest diode photocurrents. The simulation was performed for a standard 2D n-on-p FPA with square photodiodes. Fine features in measured spot-scan profiles due to the presence of FPA structure were identified, and the de-pendence of these features on the boundary conditions for diffusing charge carriers at the n-type diode regions was demonstrated. An explanation to the shape of the profiles, fully con-sistent with the computational procedure of the problem, is given.

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Journal articles on the topic 'Spot scan'

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