Applying the computer code ''beam scanning' for obtaining the electron beam energy spectrum and monitoring the beam scanning system with a faraday cup and edge current sensors

International Nuclear Information System (INIS)

Bystrov, P.A.

2014-01-01

The results of experiments simulation, obtained in the development of technique for controlling the parameters of the electron beam in a compact radiation sterilization installation are presented. Calculations were performed with a help of a computer code ''BEAM SCANNING'', developed in MRTI. Proposed a method to obtain the spectrum of the electron beam by simulation the experiments in which a Faraday cup waveforms were measured. Preliminary results are presented. Also the results of the experiments and calculations obtained in the development of the amplitude angle sensors are presented. The experiments for the beam irradiation of lead plates proposed as current sensors were modeled. Results are presented in comparison with experimental data. Also are presented the simulation results for the device designed to control scanning system.

Damage identification of beam structures using free response shapes obtained by use of a continuously scanning laser Doppler vibrometer system

Science.gov (United States)

Xu, Y. F.; Chen, Da-Ming; Zhu, W. D.

2017-08-01

Spatially dense operating deflection shapes and mode shapes can be rapidly obtained by use of a continuously scanning laser Doppler vibrometer (CSLDV) system, which sweeps its laser spot over a vibrating structure surface. This paper introduces a new type of vibration shapes called a free response shape (FRS) that can be obtained by use of a CSLDV system, and a new damage identification methodology using FRSs is developed for beam structures. An analytical expression of FRSs of a damped beam structure is derived, and FRSs from the analytical expression compare well with those from a finite element model. In the damage identification methodology, a free-response damage index (FRDI) is proposed, and damage regions can be identified near neighborhoods with consistently high values of FRDIs associated with different modes; an auxiliary FRDI is defined to assist identification of the neighborhoods. A FRDI associated with a mode consists of differences between curvatures of FRSs associated with the mode in a number of half-scan periods of a CSLDV system and those from polynomials that fit the FRSs with properly determined orders. A convergence index is proposed to determine the proper order of a polynomial fit. One advantage of the methodology is that the FRDI does not require any baseline information of an undamaged beam structure, if it is geometrically smooth and made of materials that have no stiffness and mass discontinuities. Another advantage is that FRDIs associated with multiple modes can be obtained using free response of a beam structure measured by a CSLDV system in one scan. The number of half-scan periods for calculation of the FRDI associated with a mode can be determined by use of the short-time Fourier transform. The proposed methodology was numerically and experimentally applied to identify damage in beam structures; effects of the scan frequency of a CSLDV system on qualities of obtained FRSs were experimentally investigated.

From global to local statistical shape priors novel methods to obtain accurate reconstruction results with a limited amount of training shapes

CERN Document Server

Last, Carsten

2017-01-01

This book proposes a new approach to handle the problem of limited training data. Common approaches to cope with this problem are to model the shape variability independently across predefined segments or to allow artificial shape variations that cannot be explained through the training data, both of which have their drawbacks. The approach presented uses a local shape prior in each element of the underlying data domain and couples all local shape priors via smoothness constraints. The book provides a sound mathematical foundation in order to embed this new shape prior formulation into the well-known variational image segmentation framework. The new segmentation approach so obtained allows accurate reconstruction of even complex object classes with only a few training shapes at hand.

The experience of patients participating in a small randomised control trial that explored two different interventions to reduce anxiety prior to an MRI scan.

Science.gov (United States)

Tugwell-Allsup, J; Pritchard, A W

2018-05-01

This paper reports qualitative findings from within a larger randomised control trial where a video clip or telephone conversation with a radiographer was compared to routine appointment letter and information sheet to help alleviate anxiety prior to their MRI scan. Questionnaires consisting of three free-text response questions were administered to all of the 74 patients recruited to the MRI anxiety clinical trial. The questionnaire was designed to establish patients' experiences of the intervention they had received. These questionnaires were administered post-scan. Two participants from each trial arm were also interviewed. A thematic approach was utilised for identifying recurrent categories emerging from the qualitative data which are supported by direct quotations. Participants in the interventional groups commented positively about the provision of pre-MRI scan information they received and this was contrastable with the relatively indifferent responses observed among those who received the standard information letter. Many important themes were identified including the patients needs for clear and simplified information, the experience of anticipation when waiting for the scan, and also the informally acquired information about having an MRI scan i.e. the shared experiences of friends and family. All themes highlighted the need for an inclusive and individually tailored approach to pre-scan information provision. Qualitative data collected throughout the trial is supportive of the statistical findings, where it is asserted that the use of a short video clip or a radiographer having a short conversation with patients before their scan reduces pre-scan anxiety. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Real-time out-of-plane artifact subtraction tomosynthesis imaging using prior CT for scanning beam digital x-ray system

Energy Technology Data Exchange (ETDEWEB)

Wu, Meng, E-mail: mengwu@stanford.edu [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

2014-11-01

Purpose: The scanning beam digital x-ray system (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real-time tomosynthesis in multiple planes. This system could be used for image guidance during lung nodule biopsy. However, the reconstructed images suffer from strong out-of-plane artifact due to the small tomographic angle of the system. Methods: The authors propose an out-of-plane artifact subtraction tomosynthesis (OPAST) algorithm that utilizes a prior CT volume to augment the run-time image processing. A blur-and-add (BAA) analytical model, derived from the project-to-backproject physical model, permits the generation of tomosynthesis images that are a good approximation to the shift-and-add (SAA) reconstructed image. A computationally practical algorithm is proposed to simulate images and out-of-plane artifacts from patient-specific prior CT volumes using the BAA model. A 3D image registration algorithm to align the simulated and reconstructed images is described. The accuracy of the BAA analytical model and the OPAST algorithm was evaluated using three lung cancer patients’ CT data. The OPAST and image registration algorithms were also tested with added nonrigid respiratory motions. Results: Image similarity measurements, including the correlation coefficient, mean squared error, and structural similarity index, indicated that the BAA model is very accurate in simulating the SAA images from the prior CT for the SBDX system. The shift-variant effect of the BAA model can be ignored when the shifts between SBDX images and CT volumes are within ±10 mm in the x and y directions. The nodule visibility and depth resolution are improved by subtracting simulated artifacts from the reconstructions. The image registration and OPAST are robust in the presence of added respiratory motions. The dominant artifacts in the subtraction images are caused by the mismatches between the real object and the prior CT

Constrained noninformative priors

International Nuclear Information System (INIS)

Atwood, C.L.

1994-10-01

The Jeffreys noninformative prior distribution for a single unknown parameter is the distribution corresponding to a uniform distribution in the transformed model where the unknown parameter is approximately a location parameter. To obtain a prior distribution with a specified mean but with diffusion reflecting great uncertainty, a natural generalization of the noninformative prior is the distribution corresponding to the constrained maximum entropy distribution in the transformed model. Examples are given

Bone scanning in patients with breast carcinoma

International Nuclear Information System (INIS)

Inoue, Y.; Nishi, T.; Hirose, T.; Schichijo, Y.; Ibukuro, K.

1985-01-01

Skeletal imaging using radionuclides has proved to be a sensitive method for the detection of early bony metastases from breast carcinoma. Recent studies have found a relatively low rate of abnormal scans in patients with stage I and II breast cancers, and therefore it is open to question whether bone scanning should be part of the preoperative evaluation of any patient prior to breast surgery. We reviewed our experience with bone scans in 329 patients out of 406 histologically proven breast cancer patients to determine if any or all patients should have this procedure done routinely prior to breast surgery. (orig.) [de

Supporting patients in obtaining and oncologists in providing evidence-based health-related quality of life information prior to and after esophageal cancer surgery

OpenAIRE

Jacobs, M.

2015-01-01

The overall aim of this thesis was to support patients in obtaining and oncologists in providing evidence-based HRQL data prior to and following esophageal cancer surgery. This thesis is divided in two parts. In Part I, we addressed the information needs of esophageal cancer patients prior to and following esophageal surgery, the barriers and facilitators patients experienced when discussing their information needs with their oncologist, and the development of a web-based question prompt shee...

Obtaining value prior to pulping with diethyl oxalate and oxalic acid

Science.gov (United States)

W.R. Kenealy; E. Horn; C.J. Houtman; J. Laplaza; T.W. Jeffries

2007-01-01

Pulp and paper are converted to paper products with yields of paper dependent on the wood and the process used. Even with high yield pulps there are conversion losses and with chemical pulps the yields approach 50%. The portions of the wood that do not provide product are either combusted to generate power and steam or incur a cost in waste water treatment. Value prior...

Improved compressed sensing-based cone-beam CT reconstruction using adaptive prior image constraints

Science.gov (United States)

Lee, Ho; Xing, Lei; Davidi, Ran; Li, Ruijiang; Qian, Jianguo; Lee, Rena

2012-04-01

Volumetric cone-beam CT (CBCT) images are acquired repeatedly during a course of radiation therapy and a natural question to ask is whether CBCT images obtained earlier in the process can be utilized as prior knowledge to reduce patient imaging dose in subsequent scans. The purpose of this work is to develop an adaptive prior image constrained compressed sensing (APICCS) method to solve this problem. Reconstructed images using full projections are taken on the first day of radiation therapy treatment and are used as prior images. The subsequent scans are acquired using a protocol of sparse projections. In the proposed APICCS algorithm, the prior images are utilized as an initial guess and are incorporated into the objective function in the compressed sensing (CS)-based iterative reconstruction process. Furthermore, the prior information is employed to detect any possible mismatched regions between the prior and current images for improved reconstruction. For this purpose, the prior images and the reconstructed images are classified into three anatomical regions: air, soft tissue and bone. Mismatched regions are identified by local differences of the corresponding groups in the two classified sets of images. A distance transformation is then introduced to convert the information into an adaptive voxel-dependent relaxation map. In constructing the relaxation map, the matched regions (unchanged anatomy) between the prior and current images are assigned with smaller weight values, which are translated into less influence on the CS iterative reconstruction process. On the other hand, the mismatched regions (changed anatomy) are associated with larger values and the regions are updated more by the new projection data, thus avoiding any possible adverse effects of prior images. The APICCS approach was systematically assessed by using patient data acquired under standard and low-dose protocols for qualitative and quantitative comparisons. The APICCS method provides an

Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

International Nuclear Information System (INIS)

Lawton, J J; Pulisciano, A; Palmer, R E

2009-01-01

Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

Energy Technology Data Exchange (ETDEWEB)

Lawton, J J; Pulisciano, A; Palmer, R E, E-mail: R.E.Palmer@bham.ac.u [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

2009-11-25

Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

Scanning with a Total Information Storage and Controlled Data Presentation System

Energy Technology Data Exchange (ETDEWEB)

Rejali, A. M.; Gregg, E. C.; Voelker, W. H.; Friedell, H. L. [Case Western Reserve University, Cleveland, OH (United States)

1969-01-15

This presentation demonstrates improved clinical results obtained from storing all available information received by the detector or detectors without prior modifications in a permanent memory. Permanently stored information is modified later with a special electronic imaging system with kinescope presentation in black and white or colour. Under carefully controlled circumstances this system permits immediate and innumerable degrees of erase and contrast enhancement or colour coding in fractions of a second. A profile representing the count-rate through any slice in the scanned area may be performed to determine relative distribution of radioisotopes. The advantage of this system and various clinical results in scans of myocardiums, pancreas, cardiac blood pool, placenta, etc. will be presented. (author)

A simple way to obtain backscattered electron images in a scanning transmission electron microscope.

Science.gov (United States)

Tsuruta, Hiroki; Tanaka, Shigeyasu; Tanji, Takayoshi; Morita, Chiaki

2014-08-01

We have fabricated a simple detector for backscattered electrons (BSEs) and incorporated the detector into a scanning transmission electron microscope (STEM) sample holder. Our detector was made from a 4-mm(2) Si chip. The fabrication procedure was easy, and similar to a standard transmission electron microscopy (TEM) sample thinning process based on ion milling. A TEM grid containing particle objects was fixed to the detector with a silver paste. Observations were carried out using samples of Au and latex particles at 75 and 200 kV. Such a detector provides an easy way to obtain BSE images in an STEM. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Autoradiographical Detection of Tritium in Cu-Ni Alloy by Scanning Electron Microscopy

OpenAIRE

高安, 紀; 中野, 美樹; 竹内, 豊三郎

1981-01-01

The autoradiograph of tritium dispersed in Cu-Ni alloy sheet by 6Li(n,α)3H reaction was obtained by a scanning electron microscope. Prior to the irradiation of neutrons 6Li was deposited on the sheet by evaporation. The liquid emulsion, Fuji-ER, was used in this study. The distribution of tritium was detected by the dispersion of silver grains remaining in the emulsion after the development was carried out.

Unsuccessful lung scan due to major right-to-left shunt through a sinus venosus septal defect

International Nuclear Information System (INIS)

Brendel, A.J.; Larnaudie, B.; Lambert, B.; Leccia, F.; Barat, J.L.; Ducassou, D.; Fontan, F.

1985-01-01

In a patient with a prior history of cerebral abscess and cerebral ischemia, an unsuccessful perfusion lung scan led to a radionuclide angiocardiogram using an arm vein injection. This showed a total right-to-left (R-L) shunt from the superior vena cava (SVC) to the left atrium. Repeat radionuclide study, through a leg vein, demonstrated a moderate R-L shunt and an interpretable lung scan could be obtained. Catheterization and contrast cineangiogram did not provide the exact diagnosis, the preoperative conclusion being anomalous drainage of the SVC into the left atrium, with atrial septal defect (ASD) and partial anomalous pulmonary venous connection to the SVC. The operative diagnosis was high atrial (sinus venosus) septal defect. This example of major but clinically unsuspected R-L shunt emphasizes the value of performing a perfusion lung scan, preferably in conjunction with radionuclide angiocardiography in patients with a prior history of unexplained cerebral abscess or systemic ischemia. Implications of the site of an ASD on quantitation of L-R shunts by radionuclide methods are also discussed

Comparison of the biometric values obtained by two different A-mode ultrasound devices (Eye Cubed vs. PalmScan): a transversal, descriptive, and comparative study.

Science.gov (United States)

Velez-Montoya, Raul; Shusterman, Eugene Mark; López-Miranda, Miriam Jessica; Mayorquin-Ruiz, Mariana; Salcedo-Villanueva, Guillermo; Quiroz-Mercado, Hugo; Morales-Cantón, Virgilio

2010-03-24

To assess the reliability of the measurements obtained with the PalmScan, when compared with another standardized A-mode ultrasound device, and assess the consistency and correlation between the two methods. Transversal, descriptive, and comparative study. We recorded the axial length (AL), anterior chamber depth (ACD) and lens thickness (LT) obtained with two A-mode ultrasounds (PalmScan A2000 and Eye Cubed) using an immersion technique. We compared the measurements with a two-sample t-test. Agreement between the two devices was assessed with Bland-Altman plots and 95% limits of agreement. 70 eyes of 70 patients were enrolled in this study. The measurements with the Eye Cubed of AL and ACD were shorter than the measurements taken by the PalmScan. The differences were not statistically significant regarding AL (p < 0.4) but significant regarding ACD (p < 0.001). The highest agreement between the two devices was obtained during LT measurement. The PalmScan measurements were shorter, but not statistically significantly (p < 0.2). The values of AL and LT, obtained with both devices are not identical, but within the limits of agreement. The agreement is not affected by the magnitude of the ocular dimensions (but only between range of 20 mm to 27 mm of AL and 3.5 mm to 5.7 mm of LT). A correction of about 0.5 D could be considered if an intraocular lens is being calculated. However due to the large variability of the results, the authors recommend discretion in using this conversion factor, and to adjust the power of the intraocular lenses based upon the personal experience of the surgeon.

Comparison of the Thickness and Volume of the Macula and Fovea in Patients with Anisometropic Amblyopia Prior to and after Occlusion Therapy.

Science.gov (United States)

Yoon, Dong Hee; Chun, Bo Young

2018-02-01

To compare the thickness of superior, temporal, inferior, and nasal macula and foveal thickness and volume in patients with anisometropic amblyopia prior to and after successful occlusion therapy using optical coherence tomography (OCT) measurement. Data were collected prospectively on 30 patients with unilateral anisometropic amblyopia from December 2006 to August 2007. All patients had anisometropia of 2.0 diopters or more. OCT scans were obtained for all patients at diagnosis. Occlusion therapy was then prescribed and OCT scans were obtained again at the time of successful occlusion therapy (defined as interocular difference of amblyopia. The mean duration of occlusion was 11.24 months and mean best-corrected visual acuity at diagnosis was 0.35 ± 0.12 logarithm of the minimum angle of resolution. The mean thicknesses of the superior, temporal, inferior, and nasal macula prior to and after occlusion were not significantly different (p > 0.05). However, mean foveal volume prior to occlusion therapy (0.15 ± 0.02 mm³) decreased after occlusion (0.14 ± 0.01 mm³) with statistical significance (Wilcoxon signed rank test, p = 0.025). There was a meaningful decrease in foveal volume in patients with anisometropic amblyopia after successful occlusion therapy. Whether this decrease relates to visual improvement of the amblyopic eye remains to be determined. © 2018 The Korean Ophthalmological Society

Bone scanning in severe external otitis

International Nuclear Information System (INIS)

Levin, W.J.; Shary, J.H. III; Nichols, L.T.; Lucente, F.E.

1986-01-01

Technetium99 Methylene Diphosphate bone scanning has been considered an early valuable tool to diagnose necrotizing progressive malignant external otitis. However, to our knowledge, no formal studies have actually compared bone scans of otherwise young, healthy patients with severe external otitis to scans of patients with clinical presentation of malignant external otitis. Twelve patients with only severe external otitis were studied with Technetium99 Diphosphate and were compared to known cases of malignant otitis. All scans were evaluated by two neuroradiologists with no prior knowledge of the clinical status of the patients. Nine of the 12 patients had positive bone scans with many scans resembling those reported with malignant external otitis. Interestingly, there was no consistent correlation between the severity of clinical presentation and the amount of Technetium uptake. These findings suggest that a positive bone scan alone should not be interpreted as indicative of malignant external otitis

Clinical utility of carotid duplex ultrasound prior to cardiac surgery.

Science.gov (United States)

Lin, Judith C; Kabbani, Loay S; Peterson, Edward L; Masabni, Khalil; Morgan, Jeffrey A; Brooks, Sara; Wertella, Kathleen P; Paone, Gaetano

2016-03-01

Clinical utility and cost-effectiveness of carotid duplex examination prior to cardiac surgery have been questioned by the multidisciplinary committee creating the 2012 Appropriate Use Criteria for Peripheral Vascular Laboratory Testing. We report the clinical outcomes and postoperative neurologic symptoms in patients who underwent carotid duplex ultrasound prior to open heart surgery at a tertiary institution. Using the combined databases from our clinical vascular laboratory and the Society of Thoracic Surgery, a retrospective analysis of all patients who underwent carotid duplex ultrasound within 13 months prior to open heart surgery from March 2005 to March 2013 was performed. The outcomes between those who underwent carotid duplex scanning (group A) and those who did not (group B) were compared. Among 3233 patients in the cohort who underwent cardiac surgery, 515 (15.9%) patients underwent a carotid duplex ultrasound preoperatively, and 2718 patients did not (84.1%). Among the patients who underwent carotid screening vs no screening, there was no statistically significant difference in the risk factors of cerebrovascular disease (10.9% vs 12.7%; P = .26), prior stroke (8.2% vs 7.2%; P = .41), and prior transient ischemic attack (2.9% vs 3.3%; P = .24). For those undergoing isolated coronary artery bypass grafting (CABG), 306 (17.8%) of 1723 patients underwent preoperative carotid duplex ultrasound. Among patients who had carotid screening prior to CABG, the incidence of carotid disease was low: 249 (81.4%) had minimal or mild stenosis (duplex scanning and those who did not. Primary outcomes of patients who underwent open heart surgery also showed no difference in the perioperative mortality (5.1% vs 6.9%; P = .14) and stroke (2.6% vs 2.4%; P = .85) between patients undergoing preoperative duplex scanning and those who did not. Operative intervention of severe carotid stenosis prior to isolated CABG occurred in 2 of the 17 patients (11.8%) identified who

Penalised Maximum Likelihood Simultaneous Longitudinal PET Image Reconstruction with Difference-Image Priors.

Science.gov (United States)

Ellis, Sam; Reader, Andrew J

2018-04-26

Many clinical contexts require the acquisition of multiple positron emission tomography (PET) scans of a single subject, for example to observe and quantify changes in functional behaviour in tumours after treatment in oncology. Typically, the datasets from each of these scans are reconstructed individually, without exploiting the similarities between them. We have recently shown that sharing information between longitudinal PET datasets by penalising voxel-wise differences during image reconstruction can improve reconstructed images by reducing background noise and increasing the contrast-to-noise ratio of high activity lesions. Here we present two additional novel longitudinal difference-image priors and evaluate their performance using 2D simulation studies and a 3D real dataset case study. We have previously proposed a simultaneous difference-image-based penalised maximum likelihood (PML) longitudinal image reconstruction method that encourages sparse difference images (DS-PML), and in this work we propose two further novel prior terms. The priors are designed to encourage longitudinal images with corresponding differences which have i) low entropy (DE-PML), and ii) high sparsity in their spatial gradients (DTV-PML). These two new priors and the originally proposed longitudinal prior were applied to 2D simulated treatment response [ 18 F]fluorodeoxyglucose (FDG) brain tumour datasets and compared to standard maximum likelihood expectation-maximisation (MLEM) reconstructions. These 2D simulation studies explored the effects of penalty strengths, tumour behaviour, and inter-scan coupling on reconstructed images. Finally, a real two-scan longitudinal data series acquired from a head and neck cancer patient was reconstructed with the proposed methods and the results compared to standard reconstruction methods. Using any of the three priors with an appropriate penalty strength produced images with noise levels equivalent to those seen when using standard

Validity, reliability, and reproducibility of linear measurements on digital models obtained from intraoral and cone-beam computed tomography scans of alginate impressions

NARCIS (Netherlands)

Wiranto, Matthew G.; Engelbrecht, W. Petrie; Nolthenius, Heleen E. Tutein; van der Meer, W. Joerd; Ren, Yijin

INTRODUCTION: Digital 3-dimensional models are widely used for orthodontic diagnosis. The aim of this study was to assess the validity, reliability, and reproducibility of digital models obtained from the Lava Chairside Oral scanner (3M ESPE, Seefeld, Germany) and cone-beam computed tomography scans

Enhanced sympathetic arousal in response to FMRI scanning correlates with task induced activations and deactivations.

Directory of Open Access Journals (Sweden)

Markus Muehlhan

Full Text Available It has been repeatedly shown that functional magnetic resonance imaging (fMRI triggers distress and neuroendocrine response systems. Prior studies have revealed that sympathetic arousal increases, particularly at the beginning of the examination. Against this background it appears likely that those stress reactions during the scanning procedure may influence task performance and neural correlates. However, the question how sympathetic arousal elicited by the scanning procedure itself may act as a potential confounder of fMRI data remains unresolved today. Thirty-seven scanner naive healthy subjects performed a simple cued target detection task. Levels of salivary alpha amylase (sAA, as a biomarker for sympathetic activity, were assessed in samples obtained at several time points during the lab visit. SAA increased two times, immediately prior to scanning and at the end of the scanning procedure. Neural activation related to motor preparation and timing as well as task performance was positively correlated with the first increase. Furthermore, the first sAA increase was associated with task induced deactivation (TID in frontal and parietal regions. However, these effects were restricted to the first part of the experiment. Consequently, this bias of scanner related sympathetic activation should be considered in future fMRI investigations. It is of particular importance for pharmacological investigations studying adrenergic agents and the comparison of groups with different stress vulnerabilities like patients and controls or adolescents and adults.

Influence of material surface on the scanning error of a powder-free 3D measuring system.

Science.gov (United States)

Kurz, Michael; Attin, Thomas; Mehl, Albert

2015-11-01

This study aims to evaluate the accuracy of a powder-free three-dimensional (3D) measuring system (CEREC Omnicam, Sirona), when scanning the surface of a material at different angles. Additionally, the influence of water was investigated. Nine different materials were combined with human tooth surface (enamel) to create n = 27 specimens. These materials were: Controls (InCoris TZI and Cerec Guide Bloc), ceramics (Vitablocs® Mark II and IPS Empress CAD), metals (gold and amalgam) and composites (Tetric Ceram, Filtek Supreme A2B and A2E). The highly polished samples were scanned at different angles with and without water. The 216 scans were then analyzed and descriptive statistics were obtained. The height difference between the tooth and material surfaces, as measured with the 3D scans, ranged from 0.83 μm (±2.58 μm) to -14.79 μm (±3.45 μm), while the scan noise on the materials was between 3.23 μm (±0.79 μm) and 14.24 μm (±6.79 μm) without considering the control groups. Depending on the thickness of the water film, measurement errors in the order of 300-1,600 μm could be observed. The inaccuracies between the tooth and material surfaces, as well as the scan noise for the materials, were within the range of error for measurements used for conventional impressions and are therefore negligible. The presence of water, however, greatly affects the scan. The tested powder-free 3D measuring system can safely be used to scan different material surfaces without the prior application of a powder, although drying of the surface prior to scanning is highly advisable.

Bone scanning as a routine examination of patients with mammary carcinoma; a critical consideration. [Preoperative scanning

Energy Technology Data Exchange (ETDEWEB)

Heslinga, J M; Pauwels, E K.J.; Zwaveling, A [Rijksuniversiteit Leiden (Netherlands). Academisch Ziekenhuis

1982-06-05

The usefulness of bone scanning as a routine examination was evaluated in 136 female patients with mammary carcinoma of whom 81 were staged as Columbia A and 55 as Columbia B/C. The preoperative bone scanning was positive in only 4 patients (2.9%). Consequently, bone scanning is no longer performed in the authors clinic for the preoperative detection of skeletal metastases. Bone scanning as a routine examination at 6-month intervals does not appear to be useful for the first 4 years of the follow-up, either. Most of the patients with a positive bone scan displayed other signs of skeletal metastases at the same time, such as ostealgia and a raised serum alkaline phosphatase level. Further increase of the frequency of bone scanning during the follow-up period would increase the costs considerably, almost prohibitively, even apart from the question whether such a measure might indeed significantly influence the patient's prognosis. The authors conclude that bone scanning should only be performed on the basis of the anamnesis, physical and laboratory findings, both prior to operation and during the follow-up period.

Scanning Capacitance Microscopy | Materials Science | NREL

Science.gov (United States)

obtained using scanning capacitance microscopy. Top Right: Image of p-type and n-type material, obtained 'fingers' of light-colored n-type material on a yellow and blue background representing p-type material material, obtained using scanning capacitance microscopy, in a sample semiconductor device; the image shows

SCANNING AND TRACKING MONITORING APPARATUS AND METHOD

DEFF Research Database (Denmark)

2017-01-01

Disclosed is a scanning monitoring apparatus for medical imaging, the scanning monitoring apparatus comprising a controller unit and a display, wherein the controller unit during a scanning session is configured to obtain tracking data (102) of a subject in a medical scanner, obtain scanner data ...

Influence of chemical treatment of clay to obtain polypropylene nanocomposites

International Nuclear Information System (INIS)

Rosa, Jeferson L.S.; Marques, Maria F.V.

2009-01-01

Commercial clay was chemically treated to prepare a Ziegler-Natta catalyst containing MgCl 2 and clay for the synthesis of polypropylene nanocomposites by in situ polymerization. The performance of this catalyst and materials obtained in propylene polymerization was compared with a reference catalyst (without clay) and with another, whose composition presents the same clay but without prior chemical treatment. Techniques like differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and melt flow index (MFI) measurements were performed. There was a marked reduction in catalytic activity of clay catalysts in comparison with the reference one, and a slight reduction in melting temperature of the polymers produced from first ones. The melt flow index of polymers obtained with treated clay were notably higher than those synthesized with the untreated clay, so the treated clay caused treated the production of PP's with lower molar mass. The clays showed an increase of spacing and irregular stacking of the lamellas, especially if chemically treated. (author)

Scanning electron microscopy of heat treated TiO2 nanotubes arrays obtained by anodic oxidation

Science.gov (United States)

Naranjo, D. I.; García-Vergara, S. J.; Blanco, S.

2017-12-01

Scanning electron microscopy was used to investigate the anatase-rutile transformation of self-organized TiO2 nanotubes obtained on titanium foil by anodizing and subsequent heat treatment. The anodizing was carried out at 20V in an 1% v/v HF acid and ethylene glycol:water (50:50) electrolyte at room temperature. The anodized samples were initially pre-heat treated at 450°C for 4 hours to modify the amorphous structure of TiO2 nanotubes into anatase structure. Then, the samples were heated between 600 to 800°C for different times, in order to promote the transformation to rutile structure. The formation of TiO2 nanotubes is evident by SEM images. Notably, when the samples are treated at high temperature, the formation of rutile crystals starts to become evident at the nanotubes located on the originally grain boundaries of the titanium. Thus, the anatase - rutile transformation has a close relationship with the microstructure of the titanium, more exactly with grain boundaries.

PET Scans Obtained for Evaluation of Cognitive Dysfunction

Science.gov (United States)

Silverman, Daniel H. S.; Mosconi, Lisa; Ercoli, Linda; Chen, W; Small, Gary W.

2015-01-01

The degree of intactness of human cognitive functioning for a given individual spans a wide spectrum, ranging from normal to severely demented. The differential diagnosis for the causes of impairment along that spectrum is also wide, and often difficult to distinguish clinically, which has led to an increasing role for neuroimaging tools in that evaluation. The most frequent causes of dementia are neurodegenerative disorders, Alzheimer's disease being the most prevalent among them, and they produce significant alterations in brain metabolism with devastating neuropathologic, economic, social and clinical consequences. These alterations are detectable through positron emission tomography (PET), even in their earliest stages. The most commonly performed PET studies of the brain are carried out with [18F]fluorodeoxyglucose (FDG) as the imaged radiopharmaceutical. Such scans have demonstrated diagnostic and prognostic utility in evaluating patients with cognitive impairment, and in distinguishing among primary neurodegenerative disorders and other etiologies for cognitive decline. In addition to focusing upon the effects on cerebral metabolism examined with FDG PET, some other changes occurring in the brains of cognitively impaired patients assessable with other radiotracers will be considered. As preventive and disease-modifying treatments are developed, early detection of accurately diagnosed disease processes facilitated by the use of PET has the potential to substantially impact upon the enormous human toll exacted by these diseases. PMID:18514081

Rapid-scan EPR imaging.

Science.gov (United States)

Eaton, Sandra S; Shi, Yilin; Woodcock, Lukas; Buchanan, Laura A; McPeak, Joseph; Quine, Richard W; Rinard, George A; Epel, Boris; Halpern, Howard J; Eaton, Gareth R

2017-07-01

In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250MHz. Copyright © 2017 Elsevier Inc. All rights reserved.

On the prior probabilities for two-stage Bayesian estimates

International Nuclear Information System (INIS)

Kohut, P.

1992-01-01

The method of Bayesian inference is reexamined for its applicability and for the required underlying assumptions in obtaining and using prior probability estimates. Two different approaches are suggested to determine the first-stage priors in the two-stage Bayesian analysis which avoid certain assumptions required for other techniques. In the first scheme, the prior is obtained through a true frequency based distribution generated at selected intervals utilizing actual sampling of the failure rate distributions. The population variability distribution is generated as the weighed average of the frequency distributions. The second method is based on a non-parametric Bayesian approach using the Maximum Entropy Principle. Specific features such as integral properties or selected parameters of prior distributions may be obtained with minimal assumptions. It is indicated how various quantiles may also be generated with a least square technique

Operation of a scanning near field optical microscope in reflection in combination with a scanning force microscope

NARCIS (Netherlands)

van Hulst, N.F.; Moers, M.H.P.; Moers, M.H.P.; Noordman, O.F.J.; Noordman, O.F.J.; Faulkner, T.; Segerink, Franciscus B.; van der Werf, Kees; de Grooth, B.G.; Bölger, B.; Bölger, B.

1992-01-01

Images obtained with a scanning near field optical microscope (SNOM) operating in reflection are presented. We have obtained the first results with a SiN tip as optical probe. The instrument is simultaneously operated as a scanning force microscope (SFM). Moreover, the instrument incorporates an

Reliability of capturing foot parameters using digital scanning and the neutral suspension casting technique

Science.gov (United States)

2011-01-01

Background A clinical study was conducted to determine the intra and inter-rater reliability of digital scanning and the neutral suspension casting technique to measure six foot parameters. The neutral suspension casting technique is a commonly utilised method for obtaining a negative impression of the foot prior to orthotic fabrication. Digital scanning offers an alternative to the traditional plaster of Paris techniques. Methods Twenty one healthy participants volunteered to take part in the study. Six casts and six digital scans were obtained from each participant by two raters of differing clinical experience. The foot parameters chosen for investigation were cast length (mm), forefoot width (mm), rearfoot width (mm), medial arch height (mm), lateral arch height (mm) and forefoot to rearfoot alignment (degrees). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI) were calculated to determine the intra and inter-rater reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM) and smallest real difference (SRD). Results ICC values for all foot parameters using digital scanning ranged between 0.81-0.99 for both intra and inter-rater reliability. For neutral suspension casting technique inter-rater reliability values ranged from 0.57-0.99 and intra-rater reliability values ranging from 0.36-0.99 for rater 1 and 0.49-0.99 for rater 2. Conclusions The findings of this study indicate that digital scanning is a reliable technique, irrespective of clinical experience, with reduced measurement variability in all foot parameters investigated when compared to neutral suspension casting. PMID:21375757

Measuring surface topography with scanning electron microscopy. I. EZEImage: a program to obtain 3D surface data.

Science.gov (United States)

Ponz, Ezequiel; Ladaga, Juan Luis; Bonetto, Rita Dominga

2006-04-01

Scanning electron microscopy (SEM) is widely used in the science of materials and different parameters were developed to characterize the surface roughness. In a previous work, we studied the surface topography with fractal dimension at low scale and two parameters at high scale by using the variogram, that is, variance vs. step log-log graph, of a SEM image. Those studies were carried out with the FERImage program, previously developed by us. To verify the previously accepted hypothesis by working with only an image, it is indispensable to have reliable three-dimensional (3D) surface data. In this work, a new program (EZEImage) to characterize 3D surface topography in SEM has been developed. It uses fast cross correlation and dynamic programming to obtain reliable dense height maps in a few seconds which can be displayed as an image where each gray level represents a height value. This image can be used for the FERImage program or any other software to obtain surface topography characteristics. EZEImage also generates anaglyph images as well as characterizes 3D surface topography by means of a parameter set to describe amplitude properties and three functional indices for characterizing bearing and fluid properties.

A Potential Use of 3-D Scanning to Evaluate the Chemical Composition of Pork Meat.

Science.gov (United States)

Adamczak, Lech; Chmiel, Marta; Florowski, Tomasz; Pietrzak, Dorota; Witkowski, Marcin; Barczak, Tomasz

2015-07-01

The aim of this study was to determine the possibility of 3-D scanning method in chemical composition evaluation of pork meat. The sampling material comprised neck muscles (1000 g each) obtained from 20 pork carcasses. The volumetric estimation process of the elements was conducted on the basis of point cloud collected using 3-D scanner. Knowing the weight of neck muscles, their density was calculated which was subsequently correlated with the content of basic chemical components of the pork meat (water, protein and fat content, determined by standard methods). The significant correlations (P ≤ 0.05) between meat density and water (r = 0.5213), protein (r = 0.5887), and fat (r = -0.6601) content were obtained. Based on the obtained results it seems likely to employ the 3-D scanning method to compute the meat chemical composition. The use of the 3-D scanning method in industrial practice will allow to evaluate the chemical composition of meat in online mode on a dressing and fabrication line and in a rapid, noninvasive manner. The control of the raw material using the 3-D scanning will allow to make visual assessment more objective and will enable optimal standardization of meat batches prior to processing stage. It will ensure not only the repeatability of product quality characteristics, but also optimal use of raw material-lean and fat meat. The knowledge of chemical composition of meat is essential due to legal requirements associated with mandatory nutrition facts labels on food products. © 2015 Institute of Food Technologists®

Brain Magnetic Resonance Immediately Prior To Surgery In Single Ventricles and Surgical Postponement

Science.gov (United States)

Fogel, Mark A.; Pawlowski, Tom; Schwab, Peter J.; Nicolson, Susan C.; Montenegro, Lisa M.; Berenstein, Laura Diaz; Spray, Thomas L.; Gaynor, J William; Fuller, Stephanie; Keller, Marc S.; Harris, Matthew A.; Whitehead, Kevin K.; Vossough, Arastoo; Licht, Daniel J.

2014-01-01

Background Single ventricle patients undergoing surgical reconstruction experience a high rate of brain injury; incidental findings on pre-operative brain scans may result in safety considerations involving hemorrhage extension during cardiopulmonary bypass that result in surgical postponement. Methods Single ventricle patients were studied with brain scans immediately preoperatively as part of a National Institute of Health study and were reviewed by neuroradiology immediately prior to cardiopulmonary bypass. Results One hundred and thirty four consecutive subjects recruited into the project were studied: 33 prior to stage I (3.7±1.8 days), 34 prior to bidirectional Glenn (5.8±3.5 months) and 67 prior to Fontan (3.3±1.1 years). Six (4.5%) surgeries were postponed because of concerning imaging findings on brain MRI; 2 prior to stage I, 3 prior to bidirectional Glenn and 1 prior to Fontan. Five were due to unexpected incidental findings of acute intracranial hemorrhage and one due to diffuse cerebellar cytotoxic edema; none who proceeded to surgery had these lesions. Prematurity as well as genetic syndromes were not present in any with postponed surgery. Four of 4 prior to bidirectional Glenn/Fontan with surgical delays had hypoplastic left heart syndrome compared with 44/97 who did not (P=0.048). After observation and follow up, all eventually had successful surgeries with bypass. Conclusion Preoperative brain MRI performed in children with single ventricles disclosed injuries in 4.5% leading to surgical delay; hemorrhagic lesions were most common and raised concerns for extension during surgery. The true risk of progression and need for delay of surgery due to heparinization associated with these lesions remains uncertain. PMID:25149046

A Novel Complementary Method for the Point-Scan Nondestructive Tests Based on Lamb Waves

Directory of Open Access Journals (Sweden)

Rahim Gorgin

2014-01-01

Full Text Available This study presents a novel area-scan damage identification method based on Lamb waves which can be used as a complementary method for point-scan nondestructive techniques. The proposed technique is able to identify the most probable locations of damages prior to point-scan test which lead to decreasing the time and cost of inspection. The test-piece surface was partitioned with some smaller areas and the damage probability presence of each area was evaluated. A0 mode of Lamb wave was generated and collected using a mobile handmade transducer set at each area. Subsequently, a damage presence probability index (DPPI based on the energy of captured responses was defined for each area. The area with the highest DPPI value highlights the most probable locations of damages in test-piece. Point-scan nondestructive methods can then be used once these areas are found to identify the damage in detail. The approach was validated by predicting the most probable locations of representative damages including through-thickness hole and crack in aluminum plates. The obtained experimental results demonstrated the high potential of developed method in defining the most probable locations of damages in structures.

Scanning tunneling microscopic images and scanning tunneling spectra for coupled rectangular quantum corrals

International Nuclear Information System (INIS)

Mitsuoka, Shigenori; Tamura, Akira

2011-01-01

Assuming that an electron confined by double δ-function barriers lies in a quasi-stationary state, we derived eigenstates and eigenenergies of the electron. Such an electron has a complex eigenenergy, and the imaginary part naturally leads to the lifetime of the electron associated with tunneling through barriers. We applied this point of view to the electron confined in a rectangular quantum corral (QC) on a noble metal surface, and obtained scanning tunneling microscopic images and a scanning tunneling spectrum consistent with experimental ones. We investigated the electron states confined in coupled QCs and obtained the coupled states constructed with bonding and anti-bonding states. Using those energy levels and wavefunctions we specified scanning tunneling microscope (STM) images and scanning tunneling spectra (STS) for the doubly and triply coupled QCs. In addition we pointed out the feature of resonant electron states associated with the same QCs at both ends of the triply coupled QCs.

Self-prior strategy for organ reconstruction in fluorescence molecular tomography.

Science.gov (United States)

Zhou, Yuan; Chen, Maomao; Su, Han; Luo, Jianwen

2017-10-01

The purpose of this study is to propose a strategy for organ reconstruction in fluorescence molecular tomography (FMT) without prior information from other imaging modalities, and to overcome the high cost and ionizing radiation caused by the traditional structural prior strategy. The proposed strategy is designed as an iterative architecture to solve the inverse problem of FMT. In each iteration, a short time Fourier transform (STFT) based algorithm is used to extract the self-prior information in the space-frequency energy spectrum with the assumption that the regions with higher fluorescence concentration have larger energy intensity, then the cost function of the inverse problem is modified by the self-prior information, and lastly an iterative Laplacian regularization algorithm is conducted to solve the updated inverse problem and obtains the reconstruction results. Simulations and in vivo experiments on liver reconstruction are carried out to test the performance of the self-prior strategy on organ reconstruction. The organ reconstruction results obtained by the proposed self-prior strategy are closer to the ground truth than those obtained by the iterative Tikhonov regularization (ITKR) method (traditional non-prior strategy). Significant improvements are shown in the evaluation indexes of relative locational error (RLE), relative error (RE) and contrast-to-noise ratio (CNR). The self-prior strategy improves the organ reconstruction results compared with the non-prior strategy and also overcomes the shortcomings of the traditional structural prior strategy. Various applications such as metabolic imaging and pharmacokinetic study can be aided by this strategy.

Mathematical models for correction of images, obtained at radioisotope scan

International Nuclear Information System (INIS)

Glaz, A.; Lubans, A.

2002-01-01

The images, which obtained at radioisotope scintigraphy, contain distortions. Distortions appear as a result of absorption of radiation by patient's body's tissues. Two mathematical models for reducing of such distortions are proposed. Image obtained by only one gamma camera is used in the first mathematical model. Unfortunately, this model allows processing of the images only in case, when it can be assumed, that the investigated organ has a symmetric form. The images obtained by two gamma cameras are used in the second model. It gives possibility to assume that the investigated organ has non-symmetric form and to acquire more precise results. (authors)

Proposed alteration of images of molecular orbitals obtained using a scanning tunneling microscope as a probe of electron correlation.

Science.gov (United States)

Toroz, Dimitrios; Rontani, Massimo; Corni, Stefano

2013-01-04

Scanning tunneling spectroscopy (STS) allows us to image single molecules decoupled from the supporting substrate. The obtained images are routinely interpreted as the square moduli of molecular orbitals, dressed by the mean-field electron-electron interaction. Here we demonstrate that the effect of electron correlation beyond the mean field qualitatively alters the uncorrelated STS images. Our evidence is based on the ab initio many-body calculation of STS images of planar molecules with metal centers. We find that many-body correlations alter significantly the image spectral weight close to the metal center of the molecules. This change is large enough to be accessed experimentally, surviving to molecule-substrate interactions.

Value of Duplex scanning in the selection of patients for percutaneous transluminal angioplasty

NARCIS (Netherlands)

van der Heijden, F. H.; Legemate, D. A.; van Leeuwen, M. S.; Mali, W. P.; Eikelboom, B. C.

1993-01-01

Duplex scanning is becoming increasingly important in the diagnosis and follow-up of arterial lesions, though most surgeons and radiologists currently still prefer diagnostic angiography prior to percutaneous transluminal angioplasty (PTA). We performed PTA based on Duplex scanning alone in 31

Band excitation method applicable to scanning probe microscopy

Science.gov (United States)

Jesse, Stephen [Knoxville, TN; Kalinin, Sergei V [Knoxville, TN

2010-08-17

Methods and apparatus are described for scanning probe microscopy. A method includes generating a band excitation (BE) signal having finite and predefined amplitude and phase spectrum in at least a first predefined frequency band; exciting a probe using the band excitation signal; obtaining data by measuring a response of the probe in at least a second predefined frequency band; and extracting at least one relevant dynamic parameter of the response of the probe in a predefined range including analyzing the obtained data. The BE signal can be synthesized prior to imaging (static band excitation), or adjusted at each pixel or spectroscopy step to accommodate changes in sample properties (adaptive band excitation). An apparatus includes a band excitation signal generator; a probe coupled to the band excitation signal generator; a detector coupled to the probe; and a relevant dynamic parameter extractor component coupled to the detector, the relevant dynamic parameter extractor including a processor that performs a mathematical transform selected from the group consisting of an integral transform and a discrete transform.

Immune complexes, gallium lung scans, and bronchoalveolar lavage in idiopathic interstitial pneumonitis-fibrosis

International Nuclear Information System (INIS)

Gelb, A.F.; Dreisen, R.B.; Epstein, J.D.; Silverthorne, J.D.; Bickel, Y.; Fields, M.; Border, W.A.; Taylor, C.R.

1983-01-01

We obtained results of lung immune complexes (LIC), circulating immune complexes (CIC), 48-hour gallium lung scans (scans), bronchoalveolar lavage (BAL), and pulmonary function tests in 20 patients with idiopathic interstitial pneumonitis-fibrosis. Sixteen patients had predominantly interstitial (13 cases UIP) and/or intraalveolar (3 cases DIP) cellular disease (group 1). Prior to corticosteroid therapy in group 1, scans were positive in 75 percent, CIC were elevated in 86 percent, LIC were present in 64 percent, and BAL was abnormal in 90 percent. Duration of follow-up after treatment was 3.5 +/- 1.0 year. In group 1 after treatment with corticosteroids in 13 patients and corticosteroids and penicillamine (three patients) and plasmapheresis (one patient), only four patients remain stable or improved. After corticosteroid therapy, elevated CIC returned to normal values despite progressive patient deterioration. In three patients, lung immune complexes were still detected after circulating immune complexes had returned to normal after corticosteroid therapy. In group 2 were four patients with fibrotic disease; scans and CIC were uniformly negative, LIC were weakly present in only one patient, and BAL was abnormal in all. Despite corticosteroid therapy, all have died or deteriorated. These results suggest that positive gallium lung scans, BAL, circulating immune complexes, and to a lesser extent, lung immune complexes are associated with the cellular phase of interstitial pneumonia, but do not reliably identify a corticosteroid-responsive group

Tangential scanning of hardwood logs: developing an industrial computer tomography scanner

Science.gov (United States)

Nand K. Gupta; Daniel L. Schmoldt; Bruce Isaacson

1999-01-01

It is generally believed that noninvasive scanning of hardwood logs such as computer tomography (CT) scanning prior to initial breakdown will greatly improve the processing of logs into lumber. This belief, however, has not translated into rapid development and widespread installation of industrial CT scanners for log processing. The roadblock has been more operational...

A technique for accurate planning of stereotactic brain implants prior to head ring fixation

International Nuclear Information System (INIS)

Ulin, Kenneth; Bornstein, Linda E.; Ling, Marilyn N.; Saris, Stephen; Wu, Julian K.; Curran, Bruce H.; Wazer, David E.

1997-01-01

Purpose: A two-step procedure is described for accurate planning of stereotactic brain implants prior to head-ring fixation. Methods and Materials: Approximately 2 weeks prior to implant a CT scan without the head ring is performed for treatment-planning purposes. An entry point and a reference point, both marked with barium and later tattooed, facilitate planning and permit correlation of the images with a later CT scan. A plan is generated using a conventional treatment-planning system to determine the number and activity of I-125 seeds required and the position of each catheter. I-125 seed anisotropy is taken into account by means of a modification to the treatment planning program. On the day of the implant a second CT scan is performed with the head ring affixed to the skull and with the same points marked as in the previous scan. The planned catheter coordinates are then mapped into the coordinate system of the second CT scan by means of a manual translational correction and a computer-calculated rotational correction derived from the reference point coordinates in the two scans. Results: The rotational correction algorithm was verified experimentally in a Rando phantom before it was used clinically. For analysis of the results with individual patients a third CT scan is performed 1 day following the implant and is used for calculating the final dosimetry. Conclusion: The technique that is described has two important advantages: 1) the number and activity of seeds required can be accurately determined in advance; and 2) sufficient time is allowed to derive the best possible plan

Internal scanning method as unique imaging method of optical vortex scanning microscope

Science.gov (United States)

Popiołek-Masajada, Agnieszka; Masajada, Jan; Szatkowski, Mateusz

2018-06-01

The internal scanning method is specific for the optical vortex microscope. It allows to move the vortex point inside the focused vortex beam with nanometer resolution while the whole beam stays in place. Thus the sample illuminated by the focused vortex beam can be scanned just by the vortex point. We show that this method enables high resolution imaging. The paper presents the preliminary experimental results obtained with the first basic image recovery procedure. A prospect of developing more powerful tools for topography recovery with the optical vortex scanning microscope is discussed shortly.

Results of post-laparoscopic cholecystectomy duplex scan without deep vein thrombosis prophylaxis prior to surgery

Directory of Open Access Journals (Sweden)

Mohammad Ali Pakaneh

2012-11-01

Full Text Available  Abstract Backgrounds: There are controversies among surgeons about prophylaxis of deep vein thrombosis (DVT in laparoscopic cholecystectomy. The aim of this study was the assessment of patients’ condition after laparoscopic cholecystectomy without any prophylactic measure. Methods: 100 cases of laparoscopic cholecystectomy without DVT prophylaxis were followed by duplex scanning in the first postoperative day and by physical examination and patient history at the first to second postoperative week however no clinical sign was found for DVT. Results: Only one case of partially thrombosis (1% was found by duplex scanning which was managed conservatively. Conclusion: Laparoscopic cholecystectomy may consider as a low-risk procedure and routine prophylaxis may not be justified in the absence of other risk factor. 

Tumor scanning with /sup 57/Co-bleomycin

Energy Technology Data Exchange (ETDEWEB)

Nakano, S; Hasegawa, Y; Matsuda, Minoru; Ho, T; Doi, O [Osaka Prefectural Center for Adult Diseases (Japan)

1975-06-01

The clinical application of /sup 57/Co-bleomycin as a tumor scanning radiopharmaceutical was firstly reported by Nouel and Maeda respectively. The authors conducted studies on the diagnostic significance of this tumor scanning agent and presented the results obtained in 40 patients with malignant and non malignant lesions. Six hours and 24 hours after the injection of 500 ..mu..Ci of /sup 57/Co-bleomycin, scintigrams were taken with a 3-inch scintiscanner. Positive scans were found in 20 out of 36 patients with various malignant tumors. Of 20 patients with lung cancer, positive scans were obtained in 17 cases (85%) and of 6 with breast cancer, 3 cases showed positive scans. False negative scans were obtained in another 10 cases of malignant tumors (3 cases of thyroid carcinoma, 4 cases of hepatoma, and 1 case each of gastric carcinoma, peritoneal carcinomatosis, and reticulum cell sarcoma). Of 4 patients with non malignant disease, one case of pulmonary tuberculosis showed a positive scan. In 8 cases of lung cancer and 6 of breast cancer, the relationship between the size of the excised tumor and the scintigram findings was studied. The smallest tumors detected by scintigram were 2 cm in lung cancer and 3.2 cm in breast cancer.

Form of prior for constrained thermodynamic processes with uncertainty

Science.gov (United States)

Aneja, Preety; Johal, Ramandeep S.

2015-05-01

We consider the quasi-static thermodynamic processes with constraints, but with additional uncertainty about the control parameters. Motivated by inductive reasoning, we assign prior distribution that provides a rational guess about likely values of the uncertain parameters. The priors are derived explicitly for both the entropy-conserving and the energy-conserving processes. The proposed form is useful when the constraint equation cannot be treated analytically. The inference is performed using spin-1/2 systems as models for heat reservoirs. Analytical results are derived in the high-temperatures limit. An agreement beyond linear response is found between the estimates of thermal quantities and their optimal values obtained from extremum principles. We also seek an intuitive interpretation for the prior and the estimated value of temperature obtained therefrom. We find that the prior over temperature becomes uniform over the quantity kept conserved in the process.

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates.

Science.gov (United States)

Zhang, Hao; Li, Xianqi; Chen, Yunmei; Park, Jewook; Li, An-Ping; Zhang, X-G

2017-01-01

We present an image postprocessing framework for Scanning Tunneling Microscope (STM) to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a "rubber band" model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA). The numerical results on measurement from copper(111) surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data.

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates

Directory of Open Access Journals (Sweden)

Hao Zhang

2017-01-01

Full Text Available We present an image postprocessing framework for Scanning Tunneling Microscope (STM to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a “rubber band” model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA. The numerical results on measurement from copper(111 surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data.

Adaptive nonparametric Bayesian inference using location-scale mixture priors

NARCIS (Netherlands)

Jonge, de R.; Zanten, van J.H.

2010-01-01

We study location-scale mixture priors for nonparametric statistical problems, including multivariate regression, density estimation and classification. We show that a rate-adaptive procedure can be obtained if the prior is properly constructed. In particular, we show that adaptation is achieved if

Detection of coronary artery disease - comparison of exercise stress radionuclide angiocardiography and thallium stress perfusion scanning

International Nuclear Information System (INIS)

Jengo, J.A.; Freeman, R.; Brizendine, M.; Mena, I.; St. Mary Medical Center, Long Beach, Calif.)

1980-01-01

Exercise thallium scanning and stress radionuclide angiography were compared in 16 normal subjects and 42 patients with more than 75% coronary arterial obstruction in studies using upright exercise on a bicycle ergometer. Studies at rest were subsequently obtained. Exercise thallium scans in the control group were normal in 15 and showed a defect in 1. Ejection fraction increased in all 16. During exercise, regional wall motion increased uniformly. In the group with coronary artery disease, thallium scanning revealed a new defect in the distribution of the involved arteries in 24 patients. In 15 who had a defect at rest, no new defect developed, but in 9 of the 15 new segmental wall motion defects were evident on radionuclide angiography. With exercise, ejection fraction decreased slightly. Regional wall motion abnormalities developed in the areas corresponding to thallium defects in all. Thallium scanning had a 93% and radionuclide angiography a 98% sensitivity value in detecting coronary artery disease. The respective specificity values were 94 and 100%. In patients with prior myocardial infarction who manifested new exercise abnormalities, 50% showed new thallium defects and 81% new wall motion defects

Assessment of prior learning in vocational education and training

DEFF Research Database (Denmark)

Wahlgren, Bjarne; Aarkrog, Vibe

’ knowledge, skills and competences during the students’ performances and the methods that the teachers apply in order to assess the students’ prior learning in relation to the regulations of the current VET-program. In particular the study focuses on how to assess not only the students’ explicated knowledge......The article deals about the results of a study of the assessment of prior learning among adult workers who want to obtain formal qualifications as skilled workers. The study contributes to developing methods for assessing prior learning including both the teachers’ ways of eliciting the students...... and skills but also their competences, i.e. the way the students use their skills and knowledge to perform in practice. Based on a description of the assessment procedures the article discusses central issues in relation to the assessment of prior learning. The empirical data have been obtained in the VET...

Calibration of scanning Lidar

DEFF Research Database (Denmark)

Gómez Arranz, Paula; Courtney, Michael

This report describes the tests carried out on a scanning lidar at the DTU Test Station for large wind turbines, Høvsøre. The tests were divided in two parts. In the first part, the purpose was to obtain wind speed calibrations at two heights against two cup anemometers mounted on a mast. Additio......This report describes the tests carried out on a scanning lidar at the DTU Test Station for large wind turbines, Høvsøre. The tests were divided in two parts. In the first part, the purpose was to obtain wind speed calibrations at two heights against two cup anemometers mounted on a mast...

3-d chemical imaging using angle-scan nanotomography in a soft X-ray scanning transmission X-ray microscope

Energy Technology Data Exchange (ETDEWEB)

Hitchcock, A.P.; Johansson, G.A. [McMaster, BIMR, Hamilton (Canada); Mitchell, G.E. [Dow Chemical, Analytical Science, Midland, MI (United States); Keefe, M.H. [Dow Chemical, Dow Latex, Midland, MI (United States); Tyliszcak, T. [LBNL, Advanced Light Source, Berkeley, CA (United States)

2008-08-15

Three-dimensional chemical mapping using angle scan nanotomography in a soft X-ray scanning transmission X-ray microscope (STXM) has been used to investigate the spatial distributions of a low density polyacrylate polyelectrolyte ionomer inside submicron sized polystyrene microspheres. Acquisition of tomograms at multiple photon energies provides true, quantifiable 3-d chemical sensitivity. Both pre-O 1s and C 1s results are shown. The study reveals aspects of the 3-d distribution of the polyelectrolyte that were inferred indirectly or had not been known prior to this study. The potential and challenges for extension of the technique to studies of other polymeric and to biological systems is discussed. (orig.)

Iterative reconstruction for x-ray computed tomography using prior-image induced nonlocal regularization.

Science.gov (United States)

Zhang, Hua; Huang, Jing; Ma, Jianhua; Bian, Zhaoying; Feng, Qianjin; Lu, Hongbing; Liang, Zhengrong; Chen, Wufan

2014-09-01

Repeated X-ray computed tomography (CT) scans are often required in several specific applications such as perfusion imaging, image-guided biopsy needle, image-guided intervention, and radiotherapy with noticeable benefits. However, the associated cumulative radiation dose significantly increases as comparison with that used in the conventional CT scan, which has raised major concerns in patients. In this study, to realize radiation dose reduction by reducing the X-ray tube current and exposure time (mAs) in repeated CT scans, we propose a prior-image induced nonlocal (PINL) regularization for statistical iterative reconstruction via the penalized weighted least-squares (PWLS) criteria, which we refer to as "PWLS-PINL". Specifically, the PINL regularization utilizes the redundant information in the prior image and the weighted least-squares term considers a data-dependent variance estimation, aiming to improve current low-dose image quality. Subsequently, a modified iterative successive overrelaxation algorithm is adopted to optimize the associative objective function. Experimental results on both phantom and patient data show that the present PWLS-PINL method can achieve promising gains over the other existing methods in terms of the noise reduction, low-contrast object detection, and edge detail preservation.

Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques.

Science.gov (United States)

Rai, Rathika; Kumar, S Arun; Prabhu, R; Govindan, Ranjani Thillai; Tanveer, Faiz Mohamed

2017-01-01

Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM) technique using direct and indirect optical scanning. This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS) crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4); post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

67Ga scanning and upper gastrointestinal series for gastric lymphomas

International Nuclear Information System (INIS)

Ichiya, Y.; Oshiumi, Y.; Kamoi, I.; Imoto, T.; Shimoda, Y.; Kitagawa, S.; Matsuura, K.

1982-01-01

67 Ga scanning and upper gastrointestinal (UGI) series were performed in 13 patients with gastric lymphomas before any treatment was initiated. Seven of these patients also underwent both examinations after completing chemotherapy and/or radiation therapy. Prior to treatment, all 13 patients had abnormalities on the UGI examination, and 12 of them had abnormalities on the 67 Ga scans. In 6 patients, more extensive gastric abnormalities were demonstrated by 67 Ga scanning than by UGI examination. Although persistent 67 Ga uptake after treatment was indicative of relatively poor therapeutic response, lack of uptake did not always indicate a good response to treatment

Effect of blood glucose levels on image quality in 18F fluorodeoxyglucose scanning - a case report

International Nuclear Information System (INIS)

Szeto, E.; Keane, J.

2000-01-01

Full text: In December last year, a 71-year-old gentleman presented to the Nuclear Medicine Department at St Vincent's Hospital, Sydney for an FDG coincidence detection positron emission scan. The patient had cancer of the lung with a large lesion in the left upper lobe and a small lesion in the right middle lobe. On initial investigation, this patient had a blood sugar level of 17mmol/L which was eventually reduced to 6.7mmol/L just prior to scanning. The patient was then asked to return to be rescanned without his blood sugar levels being adjusted. Just prior to his second scan, his blood sugar level was 15.4mmollL. The aim of the initial scan being repeated was to see just how important a role blood sugar levels play in the quality of a Co Pet scan. The first scan showed excellent image quality while the repeated scan showed markedly inferior image quality due to unwanted soft tissue FDG uptake. In conclusion, blood sugar levels play a significant role in output image quality in FDG coincidence detection positron emission scanning. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

Figure-ground segmentation based on class-independent shape priors

Science.gov (United States)

Li, Yang; Liu, Yang; Liu, Guojun; Guo, Maozu

2018-01-01

We propose a method to generate figure-ground segmentation by incorporating shape priors into the graph-cuts algorithm. Given an image, we first obtain a linear representation of an image and then apply directional chamfer matching to generate class-independent, nonparametric shape priors, which provide shape clues for the graph-cuts algorithm. We then enforce shape priors in a graph-cuts energy function to produce object segmentation. In contrast to previous segmentation methods, the proposed method shares shape knowledge for different semantic classes and does not require class-specific model training. Therefore, the approach obtains high-quality segmentation for objects. We experimentally validate that the proposed method outperforms previous approaches using the challenging PASCAL VOC 2010/2012 and Berkeley (BSD300) segmentation datasets.

Interpretation of secondary electron images obtained using a low vacuum SEM

International Nuclear Information System (INIS)

Toth, M.; Thiel, B.L.; Donald, A.M.

2003-01-01

Charging of insulators in a variable pressure environment was investigated in the context of secondary electron (SE) image formation. Sample charging and ionized gas molecules present in a low vacuum specimen chamber can give rise to SE image contrast. 'Charge-induced' SE contrast reflects lateral variations in the charge state of a sample caused by electron irradiation during and prior to image acquisition. This contrast corresponds to SE emission current alterations produced by sub-surface charge deposited by the electron beam. 'Ion-induced' contrast results from spatial inhomogeneities in the extent of SE signal inhibition caused by ions in the gaseous environment of a low vacuum scanning electron microscope (SEM). The inhomogeneities are caused by ion focusing onto regions of a sample that correspond to local minima in the magnitude of the surface potential (generated by sub-surface trapped charge), or topographic asperities. The two types of contrast exhibit characteristic dependencies on microscope operating parameters such as scan speed, beam current, gas pressure, detector bias and working distance. These dependencies, explained in terms of the behavior of the gaseous environment and sample charging, can serve as a basis for a correct interpretation of SE images obtained using a low vacuum SEM

The Role of Duplex Scanning in the Selection of Patients with Critical Lower-Limb Ischemia for Infrainguinal Percutaneous Transluminal Angioplasty

International Nuclear Information System (INIS)

Loefberg, Anne-Marie; Karacagil, Sadettin; Hellberg, Anders; Bostroem, Annika; Ljungman, Christer; Ostholm, Goerel

2001-01-01

Purpose: To investigate the role of duplex scanning in the selection of patients with critical lower-limb ischemia (CLI) for infrainguinal percutaneous transluminal angioplasty (PTA).Methods: One hundred and sixty-two limbs with CLI (150 patients) that underwent duplex scanning within 3 months prior to conventional diagnostic angiography (n = 88) or infrainguinal PTA (n = 74) were retrospectively studied. The findings obtained from duplex scanning and angiography were analyzed in a masked fashion by two different investigators.Results: The accuracy, sensitivity, specificity, and negative and positive predictive values of duplex scanning in the selection of patients for infrainguinal PTA were 86%, 84%, 89%, 86%, and 87% respectively. Forty-two procedures (57%) were performed at multiple arterial segments. The accuracy of duplex scanning in the selection of femoropopliteal and crural lesions for PTA was over 85%. However, the sensitivity of duplex scanning in the selection of popliteal and crural lesions for PTA was 49% and 38% respectively, compared with 80% for superior femoral artery lesions. In 39% of patients who were correctly selected for PTA, duplex scanning misdiagnosed one of the multiple lesions treated by PTA.Conclusion: Duplex scanning can safely be used for the selection of patients for infrainguinal PTA. The sensitivity of duplex scanning in the selection of lesions for PTA was less satisfactory in the popliteal and crural arteries compared with the femoropopliteal arteries

Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques

Directory of Open Access Journals (Sweden)

Rathika Rai

2017-01-01

Full Text Available Background: Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. Aim: The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM technique using direct and indirect optical scanning. Materials and Methods: This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4; post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. Results and Conclusion: Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

The clinical impact of PET scanning in patients with melanoma: A prospective study

International Nuclear Information System (INIS)

Kalff, V.; Hicks, R.J.; Binns, D.S.; Henderson, M.A.; Ainslie, J.; Jenner, D.A.

1998-01-01

Full text: Small series have shown that PET scanning using F-18 fluorodeoxyglucose (FDG), can quite accurately stage patients melanoma. At this Institute these patients are only sent for PET imaging if they have high risk melanomas ( >3 Clarke's grade primaries) or there remains any significant doubt as to their clinical staging or management after the completion of conventional screening. This prospective study examines how PET scan findings influenced the clinical management decisions in 53 patients (29 males, mean age 54±13 yrs: range 31-81 yrs) Referring doctors were asked to indicate reason for the PET scan, stage their patients on the basis of all their current investigations, and to indicate their management plans prior to PET scanning. Follow-up of subsequent patient management at 2-4 weeks post PET scan was then obtained and compared to pre PET plans. PET was used to stage 26 patients, restage 17, follow-up 5, assess recurrence in 3, and other in 2 patients. To date follow-up has shown that in 32/49 (65%) patients PET was used to triage patients to locoregional surgery (10 patients), radical radiotherapy (5 patients), or to continuing follow-up only (17 patients). Three further high risk patients with negative PET scans had sentinel mode biopsy. In only 13 patients was management already determined, with planned treatment being changed in 6. Four patients have not had their post PET scan review yet. To date proven false negative PET scans have occurred in 3 cases, 2 sentinel node biopsies showed microscopic disease, and one scan incorrectly labelled gall-bladder melanoma as hydro-nephrotic kidney. Interestingly in 3 cases, PET discovered other unsuspected tumours (rectum x 2, plasmacytoma). PET scanning has been incorporated into routine management to triage most high risk patients, but it still alters interventions in half of those patients where management has already been planned. PET clearly misses small volume disease, the importance of which is

Study of Ferrite During Refinement of Prior Austenite Grains in Microalloyed Steel Continuous Casting

Science.gov (United States)

Liu, Jiang; Wen, Guanghua; Tang, Ping

2017-12-01

The formation of coarse prior austenite grain is a key factor to promote transverse crack, and the susceptibility to the transverse crack can be reduced by refining the austenite grain size. In the present study, the high-temperature confocal laser scanning microscope (CLSM) was used to simulate two types of double phase-transformation technologies. The distribution and morphology of ferrites under different cooling conditions were analyzed, and the effects of ferrite distribution and morphology on the double phase-transformation technologies were explored to obtain the suitable double phase-change technology for the continuous casting process. The results indicate that, under the thermal cycle TH0 [the specimens were cooled down to 913 K (640 °C) at a cooling rate of 5.0 K/s (5.0 °C/s)], the width of prior austenite grain boundaries was thick, and the dislocation density at grain boundaries was high. It had strong inhibition effect on crack propagation; under the thermal cycle TH1 [the specimens were cooled down to 1073 K (800 °C) at a cooling rate of 5.0 K/s (5.0 °C/s) and then to 913 K (640 °C) at a cooling rate of 1.0 K/s (1.0 °C/s)], the width of prior austenite grain boundary was thin, and the dislocation density at grain boundaries was low. It was beneficial to crack propagation. After the first phase change, the developed film-like ferrite along the austenite grain boundaries improved the nucleation conditions of new austenitic grains and removed the inhibition effect of the prior austenite grain boundaries on the austenite grain size.

A Student-Built Scanning Tunneling Microscope

Science.gov (United States)

Ekkens, Tom

2015-01-01

Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

Sets of priors reflecting prior-data conflict and agreement

NARCIS (Netherlands)

Walter, G.M.; Coolen, F.P.A.; Carvalho, J.P.; Lesot, M.-J.; Kaymak, U.; Vieira, S.; Bouchon-Meunier, B.; Yager, R.R.

2016-01-01

Bayesian inference enables combination of observations with prior knowledge in the reasoning process. The choice of a particular prior distribution to represent the available prior knowledge is, however, often debatable, especially when prior knowledge is limited or data are scarce, as then

Towards Robust Self-Calibration for Handheld 3d Line Laser Scanning

Science.gov (United States)

Bleier, M.; Nüchter, A.

2017-11-01

This paper studies self-calibration of a structured light system, which reconstructs 3D information using video from a static consumer camera and a handheld cross line laser projector. Intersections between the individual laser curves and geometric constraints on the relative position of the laser planes are exploited to achieve dense 3D reconstruction. This is possible without any prior knowledge of the movement of the projector. However, inaccurrately extracted laser lines introduce noise in the detected intersection positions and therefore distort the reconstruction result. Furthermore, when scanning objects with specular reflections, such as glossy painted or metalic surfaces, the reflections are often extracted from the camera image as erroneous laser curves. In this paper we investiagte how robust estimates of the parameters of the laser planes can be obtained despite of noisy detections.

A prospective study of the clinical impact of PET scanning in lung cancer patients

International Nuclear Information System (INIS)

Hicks, R.J.; Kalff, V.; Binns, D.S.; McManus, M.; Millward, M.; Ball, D.J.

1998-01-01

Full text: PET scanning using F-18 fluorodeoxyglucose (FDG), has been shown to very accurately stage patients with non-small cell lung cancer. At this Institute these patients are only sent for PET imaging where there remains any significant doubt as to their clinical staging or management after the completion of conventional screening test including CT scanning. This study examines how PET scan findings influenced the clinical management decisions in 45 consecutive patients (26 males, mean age 69±9 yrs: range 36-78 yrs). Referring doctors were asked to indicate reason for the PET scan, stage their patients on the basis of aU their current investigations, including CT scans, and to indicate their management plans prior to PET scanning. Follow-up of subsequent patient management at 2-4 weeks post PET scan was then obtained and compared to pre scan plans. Results:, PET was used to stage 27 patients, restage 8, plan radiotherapy in 4, post treatment follow-up in 3, assess solitary nodules in 2, and as a baseline for experimental therapy in 1. To date follow-up has shown that in 14 (31%) patients PET scanning found new distant abnormalities which caused planned radical surgery or radiotherapy to be changed to palliative treatment only. Following PET findings, which clarified equivocal findings on other imaging modalities 9 patients underwent curative lung surgery. This found localised disease only in the 5 who have had surgery to this time. Similarly 7 patients continued on to have radical radiotherapy. In 3 patients, original treatment protocols changed (smaller radiation portal, surgery after good response to radiotherapy, planned chemotherapy ceased). In 8(18%) patients PET scans did not alter planned therapy. 1 patient awaits follow-up. Conclusions: In carefully selected patients with lung cancer, PET scanning significantly affected management decisions in 82%. It was used not only to spare unnecessary treatment, but also to target treatment appropriate to

Efficiency of a concentric matrix track detector surface scanning

International Nuclear Information System (INIS)

Bek-Uzarov, Dj.; Nikezic, D.; Kostic, D.; Krstic, D.; Cuknic, O.

1995-01-01

Heavy particle ionizing radiation track counting on the surface of a solid state round surface detector is made using the microscope and scanning step by step by a round field of vision. The whole solid state detector surface could not be fully or completely covered by round fields of visions. Therefore detector surface could be divided on the two parts, the larger surface, being under fields of vision, really scanned and no scanned missed or omitted surface. The ratio between omitted and scanned surfaces is so called track scanning efficiency. The knowledge of really counted, or scanned surface is a important value for evaluating the real surface track density an exposed solid state track detector. In the paper a matrix of a concentric field of vision made around the first microscope field of vision placed in center of the round disc of the scanned track detector is proposed. In a such scanning matrix the real scanned surface could be easy calculated and by the microscope scanning made as well. By this way scanned surface is very precisely obtained as well. Precise knowledge of scanned and omitted surface allows to obtain more precise scanning efficiency factor as well as real surface track density, the main parameter in solid state track detection measurements. (author)

Fully automatic detection of corresponding anatomical landmarks in volume scans of different respiratory state

International Nuclear Information System (INIS)

Berlinger, Kajetan; Roth, Michael; Sauer, Otto; Vences, Lucia; Schweikard, Achim

2006-01-01

A method is described which provides fully automatic detection of corresponding anatomical landmarks in volume scans taken at different respiratory states. The resulting control points are needed for creating a volumetric deformation model for motion compensation in radiotherapy. Prior to treatment two CT volumes are taken, one scan during inhalation, one during exhalation. These scans and the detected control point pairs are taken as input for creating the four-dimensional model by using thin-plate splines

DETERMINING GEOMETRIC PARAMETERS OF AGRICULTURAL TREES FROM LASER SCANNING DATA OBTAINED WITH UNMANNED AERIAL VEHICLE

Directory of Open Access Journals (Sweden)

E. Hadas

2018-05-01

Full Text Available The estimation of dendrometric parameters has become an important issue for agriculture planning and for the efficient management of orchards. Airborne Laser Scanning (ALS data is widely used in forestry and many algorithms for automatic estimation of dendrometric parameters of individual forest trees were developed. Unfortunately, due to significant differences between forest and fruit trees, some contradictions exist against adopting the achievements of forestry science to agricultural studies indiscriminately. In this study we present the methodology to identify individual trees in apple orchard and estimate heights of individual trees, using high-density LiDAR data (3200 points/m2 obtained with Unmanned Aerial Vehicle (UAV equipped with Velodyne HDL32-E sensor. The processing strategy combines the alpha-shape algorithm, principal component analysis (PCA and detection of local minima. The alpha-shape algorithm is used to separate tree rows. In order to separate trees in a single row, we detect local minima on the canopy profile and slice polygons from alpha-shape results. We successfully separated 92 % of trees in the test area. 6 % of trees in orchard were not separated from each other and 2 % were sliced into two polygons. The RMSE of tree heights determined from the point clouds compared to field measurements was equal to 0.09 m, and the correlation coefficient was equal to 0.96. The results confirm the usefulness of LiDAR data from UAV platform in orchard inventory.

Determining Geometric Parameters of Agricultural Trees from Laser Scanning Data Obtained with Unmanned Aerial Vehicle

Science.gov (United States)

Hadas, E.; Jozkow, G.; Walicka, A.; Borkowski, A.

2018-05-01

The estimation of dendrometric parameters has become an important issue for agriculture planning and for the efficient management of orchards. Airborne Laser Scanning (ALS) data is widely used in forestry and many algorithms for automatic estimation of dendrometric parameters of individual forest trees were developed. Unfortunately, due to significant differences between forest and fruit trees, some contradictions exist against adopting the achievements of forestry science to agricultural studies indiscriminately. In this study we present the methodology to identify individual trees in apple orchard and estimate heights of individual trees, using high-density LiDAR data (3200 points/m2) obtained with Unmanned Aerial Vehicle (UAV) equipped with Velodyne HDL32-E sensor. The processing strategy combines the alpha-shape algorithm, principal component analysis (PCA) and detection of local minima. The alpha-shape algorithm is used to separate tree rows. In order to separate trees in a single row, we detect local minima on the canopy profile and slice polygons from alpha-shape results. We successfully separated 92 % of trees in the test area. 6 % of trees in orchard were not separated from each other and 2 % were sliced into two polygons. The RMSE of tree heights determined from the point clouds compared to field measurements was equal to 0.09 m, and the correlation coefficient was equal to 0.96. The results confirm the usefulness of LiDAR data from UAV platform in orchard inventory.

Parallelism between gradient temperature raman spectroscopy and differential scanning calorimetry results

Science.gov (United States)

Temperature dependent Raman spectroscopy (TDR) applies the temperature gradients utilized in differential scanning calorimetry (DSC) to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements that occur just prior to phase transitions. Herein we apply TDR and D...

SU-E-J-68: Adaptive Radiotherapy of Head and Neck Cancer: Re-Planning Based On Prior Dose

Energy Technology Data Exchange (ETDEWEB)

Dogan, N; Padgett, K [University of Miami Miller School of Medicine, Miami, FL (United States); Evans, J; Sleeman, W; Song, S [Virginia Commonwealth University, Richmond, VA (United States); Fatyga, M [Mayo Clinic Arizona, Phoenix, AZ (United States)

2015-06-15

Purpose: Adaptive Radiotherapy (ART) with frequent CT imaging has been used to improve dosimetric accuracy by accounting for anatomical variations, such as primary tumor shrinkage and/or body weight loss, in Head and Neck (H&N) patients. In most ART strategies, the difference between the planned and the delivered dose is estimated by generating new plans on repeated CT scans using dose-volume constraints used with the initial planning CT without considering already delivered dose. The aim of this study was to assess the dosimetric gains achieved by re-planning based on prior dose by comparing them to re-planning not based-on prior dose for H&N patients. Methods: Ten locally-advanced H&N cancer patients were selected for this study. For each patient, six weekly CT imaging were acquired during the course of radiotherapy. PTVs, parotids, cord, brainstem, and esophagus were contoured on both planning and six weekly CT images. ART with weekly re-plans were done by two strategies: 1) Generating a new optimized IMRT plan without including prior dose from previous fractions (NoPriorDose) and 2) Generating a new optimized IMRT plan based on the prior dose given from previous fractions (PriorDose). Deformable image registration was used to accumulate the dose distributions between planning and six weekly CT scans. The differences in accumulated doses for both strategies were evaluated using the DVH constraints for all structures. Results: On average, the differences in accumulated doses for PTV1, PTV2 and PTV3 for NoPriorDose and PriorDose strategies were <2%. The differences in Dmean to the cord and brainstem were within 3%. The esophagus Dmean was reduced by 2% using PriorDose. PriorDose strategy, however, reduced the left parotid D50 and Dmean by 15% and 14% respectively. Conclusion: This study demonstrated significant parotid sparing, potentially reducing xerostomia, by using ART with IMRT optimization based on prior dose for weekly re-planning of H&N cancer patients.

Automated Agatston score computation in non-ECG gated CT scans using deep learning

Science.gov (United States)

Cano-Espinosa, Carlos; González, Germán.; Washko, George R.; Cazorla, Miguel; San José Estépar, Raúl

2018-03-01

Introduction: The Agatston score is a well-established metric of cardiovascular disease related to clinical outcomes. It is computed from CT scans by a) measuring the volume and intensity of the atherosclerotic plaques and b) aggregating such information in an index. Objective: To generate a convolutional neural network that inputs a non-contrast chest CT scan and outputs the Agatston score associated with it directly, without a prior segmentation of Coronary Artery Calcifications (CAC). Materials and methods: We use a database of 5973 non-contrast non-ECG gated chest CT scans where the Agatston score has been manually computed. The heart of each scan is cropped automatically using an object detector. The database is split in 4973 cases for training and 1000 for testing. We train a 3D deep convolutional neural network to regress the Agatston score directly from the extracted hearts. Results: The proposed method yields a Pearson correlation coefficient of r = 0.93; p <= 0.0001 against manual reference standard in the 1000 test cases. It further stratifies correctly 72.6% of the cases with respect to standard risk groups. This compares to more complex state-of-the-art methods based on prior segmentations of the CACs, which achieve r = 0.94 in ECG-gated pulmonary CT. Conclusions: A convolutional neural network can regress the Agatston score from the image of the heart directly, without a prior segmentation of the CACs. This is a new and simpler paradigm in the Agatston score computation that yields similar results to the state-of-the-art literature.

Towards vortex imaging with scanning tunneling microscope

International Nuclear Information System (INIS)

Fuchs, Dan T.

1994-02-01

A low temperature, Besocke beetle type scanning tunneling microscope, with a scan range of 10 by 10 microns was built. The scanning tunneling microscope was calibrates for various temperatures and tested on several samples. Gold monolayers evaporated at 400 deg C were resolved and their dynamic behavior observed. Atomic resolution images of graphite were obtained. The scanning tunneling microscope was designed for future applications of vortex imaging in superconductors. The special design considerations for this application are discussed and the physics underlying it reviewed. (author)

Testability evaluation using prior information of multiple sources

Institute of Scientific and Technical Information of China (English)

Wang Chao; Qiu Jing; Liu Guanjun; Zhang Yong

2014-01-01

Testability plays an important role in improving the readiness and decreasing the life-cycle cost of equipment. Testability demonstration and evaluation is of significance in measuring such testability indexes as fault detection rate (FDR) and fault isolation rate (FIR), which is useful to the producer in mastering the testability level and improving the testability design, and helpful to the consumer in making purchase decisions. Aiming at the problems with a small sample of testabil-ity demonstration test data (TDTD) such as low evaluation confidence and inaccurate result, a test-ability evaluation method is proposed based on the prior information of multiple sources and Bayes theory. Firstly, the types of prior information are analyzed. The maximum entropy method is applied to the prior information with the mean and interval estimate forms on the testability index to obtain the parameters of prior probability density function (PDF), and the empirical Bayesian method is used to get the parameters for the prior information with a success-fail form. Then, a parametrical data consistency check method is used to check the compatibility between all the sources of prior information and TDTD. For the prior information to pass the check, the prior credibility is calculated. A mixed prior distribution is formed based on the prior PDFs and the corresponding credibility. The Bayesian posterior distribution model is acquired with the mixed prior distribution and TDTD, based on which the point and interval estimates are calculated. Finally, examples of a flying control system are used to verify the proposed method. The results show that the proposed method is feasible and effective.

Laser Scanning in Forests

Directory of Open Access Journals (Sweden)

Håkan Olsson

2012-09-01

Full Text Available The introduction of Airborne Laser Scanning (ALS to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System, IMU (Inertial Measurement Unit and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based forest inventory approaches have been reported feasible for operational activities [8–12]. ALS is currently operationally applied for stand level forest inventories, for example, in Nordic countries. In Finland alone, the adoption of ALS for forest data collection has led to an annual savings of around 20 M€/year, and the work is mainly done by companies instead of governmental organizations. In spite of the long implementation times and there being a limited tradition of making changes in the forest sector, laser scanning was commercially and operationally applied after about only one decade of research. When analyzing high-ranked journal papers from ISI Web of Science, the topic of laser scanning of forests has been the driving force for the whole laser scanning research society over the last decade. Thus, the topic “laser scanning in forests” has provided a significant industrial, societal and scientific impact. [...

Status of automated nuclear scanning systems

International Nuclear Information System (INIS)

Gold, R.; Roberts, J.H.; Preston, C.C.; McNeece, J.P.; Ruddy, F.H.

1983-07-01

Present day minicomputers and microprocessors enable a range of automation, from partial to total, of tasks once thought beyond approach. The status of three computer controlled systems for quantitative track measurements is reviewed. Two systems, the Hanford optical track scanner (HOTS) and an automated scanning electron microscope (ASEM) are used for scanning solid state track recorders (SSTR). The third systems, the emulsion scanning processor (ESP), is an interactive system used to measure the length of proton tracks in nuclear research emulsions (NRE). Current limitations of these systems for quantitative track scanning are presented. Experimental uncertainties attained with these computer controlled systems are described using results obtained from reactor neutron dosimetry

Prior Elicitation, Assessment and Inference with a Dirichlet Prior

Directory of Open Access Journals (Sweden)

Michael Evans

2017-10-01

Full Text Available Methods are developed for eliciting a Dirichlet prior based upon stating bounds on the individual probabilities that hold with high prior probability. This approach to selecting a prior is applied to a contingency table problem where it is demonstrated how to assess the prior with respect to the bias it induces as well as how to check for prior-data conflict. It is shown that the assessment of a hypothesis via relative belief can easily take into account what it means for the falsity of the hypothesis to correspond to a difference of practical importance and provide evidence in favor of a hypothesis.

Fermi surface contours obtained from scanning tunneling microscope images around surface point defects

International Nuclear Information System (INIS)

Khotkevych-Sanina, N V; Kolesnichenko, Yu A; Van Ruitenbeek, J M

2013-01-01

We present a theoretical analysis of the standing wave patterns in scanning tunneling microscope (STM) images, which occur around surface point defects. We consider arbitrary dispersion relations for the surface states and calculate the conductance for a system containing a small-size tunnel contact and a surface impurity. We find rigorous theoretical relations between the interference patterns in the real-space STM images, their Fourier transforms and the Fermi contours of two-dimensional electrons. We propose a new method for reconstructing Fermi contours of surface electron states, directly from the real-space STM images around isolated surface defects. (paper)

Scanning holograms

International Nuclear Information System (INIS)

Natali, S.

1984-01-01

This chapter reports on the scanning of 1000 holograms taken in HOBC at CERN. Each hologram is triggered by an interaction in the chamber, the primary particles being pions at 340 GeV/c. The aim of the experiment is the study of charm production. The holograms, recorded on 50 mm film with the ''in line'' technique, can be analyzed by shining a parallel expanded laser beam through the film, obtaining immediately above it the real image of the chamber which can then be scanned and measured with a technique half way between emulsions and bubble chambers. The results indicate that holograms can be analyzed as quickly and reliably as in other visual techniques and that to them is open the same order of magnitude of large scale experiments

Comparison of thallium-201 scan and Tc-99m sestamibi scan in the differential diagnosis of breast mass

Energy Technology Data Exchange (ETDEWEB)

Cho, Ihn Ho; Won, Kyu Jang; Lee, Hyung Woo; Lee, Soon Jung [College of Medicine, Yonsei Univ., Seoul (Korea, Republic of)

1999-02-01

We performed this study to compare Tl-201 and Tc-99m MIBI scans for the differentiation of malignant from benign breast mass. Thirty-eight female patients underwent Tl-201 breast scan and thirty-two of them also underwent Tc-99m MIBI scan of the breast. After intravenous injection of 74-111 MBq of Tl-201, early (10 minutes) and delayed (3 hours) images were obtained. Then, 555-740 MBq of Tc-99m MIBI was injected and images after 30 minutes were obtained. We compared Tl-201 and Tc-99m MIBI scans with pathologic results. Twenty-three patients were confirmed to have infiltrating duct carcinoma and fifteen patients to have benign breast mass by excisonal biopsy. The sensitivity of early and delayed Tl-201 scan and Tc-99m MIBI scan in the detection of malignant breast lesion were 100% (23/23), 82% (18/22), and 90% (18/20), respectively. The sensitivity of early Tl-201 scan was significantly higher than that of delayed Tl-201 scan, (p<0.05). The specificity of early and delayed Tl-201 scan and Tc-99m MIBI scan were 73% (11/15), 73% (11/15) and 83% (10/12), respectively (p: not significant). Three patients out of nine with fibroadenoma and one patient with atypical duct hyperplasia were false positive in both early and delayed Tl-201 scans. The size of fibroadenoma with false positive in early and delayed Tl-201 scan (4 cases) was larger than that of 11 fibroadenoma with true negative scan (p<0.01). Metastatic axillary lymph node involvement was present in fifteen patients. The sensitivity to detect metastatic nodes was 38% (5/13) for early Tl-201 images, 15% (2/13) for delayed Tl-201 images, 58% (7/12) for Tc-99m MIBI planar images and 67% (4/6) for Tc-99m MIBI SPECT. The sensitivity of Tc-99m MIBI planar or SPECT was significantly higher than that of delayed Tl-201 images (p<0.05). Early Tl-201 and Tc-99m MIBI scan are useful noninvasive methods to differentiate malignant from benign mass of breast. Tc-99m MIBI scan was sensitive in detecting axillary lymph node

Virtual animation of victim-specific 3D models obtained from CT scans for forensic reconstructions

DEFF Research Database (Denmark)

Villa, C; Olsen, K B; Hansen, S H

2017-01-01

Post-mortem CT scanning (PMCT) has been introduced at several forensic medical institutions many years ago and has proved to be a useful tool. 3D models of bones, skin, internal organs and bullet paths can rapidly be generated using post-processing software. These 3D models reflect the individual...

Testability evaluation using prior information of multiple sources

Directory of Open Access Journals (Sweden)

Wang Chao

2014-08-01

Full Text Available Testability plays an important role in improving the readiness and decreasing the life-cycle cost of equipment. Testability demonstration and evaluation is of significance in measuring such testability indexes as fault detection rate (FDR and fault isolation rate (FIR, which is useful to the producer in mastering the testability level and improving the testability design, and helpful to the consumer in making purchase decisions. Aiming at the problems with a small sample of testability demonstration test data (TDTD such as low evaluation confidence and inaccurate result, a testability evaluation method is proposed based on the prior information of multiple sources and Bayes theory. Firstly, the types of prior information are analyzed. The maximum entropy method is applied to the prior information with the mean and interval estimate forms on the testability index to obtain the parameters of prior probability density function (PDF, and the empirical Bayesian method is used to get the parameters for the prior information with a success-fail form. Then, a parametrical data consistency check method is used to check the compatibility between all the sources of prior information and TDTD. For the prior information to pass the check, the prior credibility is calculated. A mixed prior distribution is formed based on the prior PDFs and the corresponding credibility. The Bayesian posterior distribution model is acquired with the mixed prior distribution and TDTD, based on which the point and interval estimates are calculated. Finally, examples of a flying control system are used to verify the proposed method. The results show that the proposed method is feasible and effective.

A Scan Statistic for Continuous Data Based on the Normal Probability Model

OpenAIRE

Konty, Kevin; Kulldorff, Martin; Huang, Lan

2009-01-01

Abstract Temporal, spatial and space-time scan statistics are commonly used to detect and evaluate the statistical significance of temporal and/or geographical disease clusters, without any prior assumptions on the location, time period or size of those clusters. Scan statistics are mostly used for count data, such as disease incidence or mortality. Sometimes there is an interest in looking for clusters with respect to a continuous variable, such as lead levels in children or low birth weight...

Glass transition of anhydrous starch by fast scanning calorimetry.

Science.gov (United States)

Monnier, Xavier; Maigret, Jean-Eudes; Lourdin, Denis; Saiter, Allisson

2017-10-01

By means of fast scanning calorimetry, the glass transition of anhydrous amorphous starch has been measured. With a scanning rate of 2000Ks -1 , thermal degradation of starch prior to the glass transition has been inhibited. To certify the glass transition measurement, structural relaxation of the glassy state has been investigated through physical aging as well as the concept of limiting fictive temperature. In both cases, characteristic enthalpy recovery peaks related to the structural relaxation of the glass have been observed. Thermal lag corrections based on the comparison of glass transition temperatures measured by means of differential and fast scanning calorimetry have been proposed. The complementary investigations give an anhydrous amorphous starch glass transition temperature of 312±7°C. This estimation correlates with previous extrapolation performed on hydrated starches. Copyright © 2017 Elsevier Ltd. All rights reserved.

Scanning tunneling microscopy III theory of STM and related scanning probe methods

CERN Document Server

Güntherodt, Hans-Joachim

1993-01-01

While the first two volumes on Scanning Tunneling Microscopy (STM) and its related scanning probe (SXM) methods have mainly concentrated on intro­ ducing the experimental techniques, as well as their various applications in different research fields, this third volume is exclusively devoted to the theory of STM and related SXM methods. As the experimental techniques including the reproducibility of the experimental results have advanced, more and more theorists have become attracted to focus on issues related to STM and SXM. The increasing effort in the development of theoretical concepts for STM/SXM has led to considerable improvements in understanding the contrast mechanism as well as the experimental conditions necessary to obtain reliable data. Therefore, this third volume on STM/SXM is not written by theorists for theorists, but rather for every scientist who is not satisfied by just obtaining real­ space images of surface structures by STM/SXM. After a brief introduction (Chap. 1), N. D. Lang first co...

Using Information From Prior Satellite Scans to Improve Cloud Detection Near the Day-Night Terminator

Science.gov (United States)

Yost, Christopher R.; Minnis, Patrick; Trepte, Qing Z.; Palikonda, Rabindra; Ayers, Jeffrey K.; Spangenberg, Doulas A.

2012-01-01

With geostationary satellite data it is possible to have a continuous record of diurnal cycles of cloud properties for a large portion of the globe. Daytime cloud property retrieval algorithms are typically superior to nighttime algorithms because daytime methods utilize measurements of reflected solar radiation. However, reflected solar radiation is difficult to accurately model for high solar zenith angles where the amount of incident radiation is small. Clear and cloudy scenes can exhibit very small differences in reflected radiation and threshold-based cloud detection methods have more difficulty setting the proper thresholds for accurate cloud detection. Because top-of-atmosphere radiances are typically more accurately modeled outside the terminator region, information from previous scans can help guide cloud detection near the terminator. This paper presents an algorithm that uses cloud fraction and clear and cloudy infrared brightness temperatures from previous satellite scan times to improve the performance of a threshold-based cloud mask near the terminator. Comparisons of daytime, nighttime, and terminator cloud fraction derived from Geostationary Operational Environmental Satellite (GOES) radiance measurements show that the algorithm greatly reduces the number of false cloud detections and smoothes the transition from the daytime to the nighttime clod detection algorithm. Comparisons with the Geoscience Laser Altimeter System (GLAS) data show that using this algorithm decreases the number of false detections by approximately 20 percentage points.

Challenges in 3D scanning: Focusing on Ears and Multiple View Stereopsis

DEFF Research Database (Denmark)

Jensen, Rasmus Ramsbøl

It is the goal of this thesis to address some of the challenges in 3D scanning. This has been done with focus on direct in-ear scanning and on Multiple View Stereopsis. Seven papers have been produced over the course of the Ph.D., out of which, six have been included. Two papers concern volumetric...... segmentation based on Markov Random Fields. These have been formulated to address problems relating to noise ltering in direct in-ear scanning and Intracranial Volume estimation. Another two papers have been produced on the topic of recovering surface data based on a strong statistical prior. This was done...

Comparison of SUV and Patlak slope for monitoring of cancer therapy using serial PET scans

International Nuclear Information System (INIS)

Freedman, Nanette M.T.; Sundaram, Senthil K.; Kurdziel, Karen; Carrasquillo, Jorge A.; Whatley, Millie; Carson, Joann M.; Sellers, David; Libutti, Steven K.; Yang, James C.; Bacharach, Stephen L.

2003-01-01

The standardized uptake value (SUV) and the slope of the Patlak plot (K) have both been proposed as indices to monitor the progress of disease during cancer therapy. Although a good correlation has been reported between SUV and K, they are not equivalent, and may not be equally affected by metabolic changes occurring during disease progression or therapy. We wished to compare changes in tumor SUV with changes in K during serial positron emission tomography (PET) scans for monitoring therapy. Thirteen patients enrolled in a protocol to treat renal cell carcinoma metastases were studied. Serial dynamic fluorodeoxyglucose (FDG) PET scans and computed tomography (CT) and magnetic resonance (MR) scans were performed once prior to treatment, once at 36±2 days after the start of treatment, and (in 7/13 subjects, 16/27 lesions) a third time at 92±9 days after the start of treatment. This resulted in a total of 33 scans, and 70 tumor Patlak and SUV values (one value for each lesion at each time point). SUV and K were measured over one to four predefined tumors/patient at each time point. The input function was obtained from regions of interest over the heart, combined, if necessary, with late blood samples. Over all tumors and scans, SUV and K correlated well (r=0.97, P<0.0001). However, change in SUV with treatment over all tumor scan pairs was much less well correlated with the corresponding change in K (r=0.73, P<0.0001). The absolute difference in % change was outside the 95% confidence limits expected from previous variability studies in 6 of 43 pairs of tumor scans, and greater than 50% in 2 of 43 tumor scan pairs. In four of the six cases, the two indices predicted opposing therapeutic outcomes. Similar results were obtained for SUV normalized by body weight or body surface area and for SUVs using mean or maximum count. Changes in CT and MR tumor cross-product dimensions correlated poorly with each other (r=0.47, P=NS), and so could not be used to determine the

Variational segmentation problems using prior knowledge in imaging and vision

DEFF Research Database (Denmark)

Fundana, Ketut

This dissertation addresses variational formulation of segmentation problems using prior knowledge. Variational models are among the most successful approaches for solving many Computer Vision and Image Processing problems. The models aim at finding the solution to a given energy functional defined......, prior knowledge is needed to obtain the desired solution. The introduction of shape priors in particular, has proven to be an effective way to segment objects of interests. Firstly, we propose a prior-based variational segmentation model to segment objects of interest in image sequences, that can deal....... Many objects have high variability in shape and orientation. This often leads to unsatisfactory results, when using a segmentation model with single shape template. One way to solve this is by using more sophisticated shape models. We propose to incorporate shape priors from a shape sub...

Implementation of dual energy CT scanning

International Nuclear Information System (INIS)

Marshall, W.; Hall, E.; Doost-Hoseini, A.; Alvarez, R.; Macovski, A.; Cassel, D.

1984-01-01

A prereconstruction method for dual energy (PREDECT) analysis of CT scans is described. In theory, this method can (a) eliminate beam hardening and produce an accuracy comparable with monoenergetic scans and (b) provide the effective atomic number and electron density of any voxel scanned. The implementation proves these statements and eliminates some of the objectionable noise. A phantom was constructed with a cylindrical sleeve-like compartment containing known amounts of high atomic number material simulating a removable skull. Conventional scans, with and without this beam hardener, were done of a water bath containing tubes of high electron and high atomic number material. Dual energy scans were then done for PREDECT. To increase the effective separation of the low and high energy beams by using more appropriate tube filtration, a beam filter changer was fabricated containing erbium, tungsten, aluminum, and steel. Erbium, tungsten, and steel were used at high energy and aluminum, steel, and erbium at low energy for data acquisition. The reconstructions were compared visually and numerically for noise levels with the original steel only filtration. A decrease was found in noise down to approximately one-half the prior level when erbium/aluminum or tungsten/aluminum replaced the steel/steel filter. Erbium and tungsten were equally effective. Steel/erbium and steel/aluminum also significantly reduced image noise. The noise in the photoelectric (P) and Compton (C) images is negatively correlated. At any pixel, if the noise is positive in the P image, it is most probably negative in the C. Using this fact, the noise was reduced by postreconstruction processing

Linking IMAGE 2 and WORLD SCAN

International Nuclear Information System (INIS)

Gelauff, G.; Geurts, B.; Gielen, A.; Den Ouden, A.; Alcamo, J.; Gerlagh, R.

1995-01-01

The links between the climate model IMAGE 2 and the economic model WORLD SCAN, which are set up to obtain an integrated scenario instrument for comprehensive and consistent climate-economy scenarios, are presented and discussed. The links are made with respect to energy (in WORLD SCAN) and agriculture (in IMAGE 2), thus providing a consistent linkage with feedbacks running both ways. 2 figs., 1 tab

Whole body scan system based on γ camera

International Nuclear Information System (INIS)

Ma Tianyu; Jin Yongjie

2001-01-01

Most existing domestic γ cameras can not perform whole body scan protocol, which is of important use in clinic. The authors designed a set of whole body scan system, which is made up of a scan bed, an ISA interface card controlling the scan bed and the data acquisition software based on a data acquisition and image processing system for γ cameras. The image was obtained in clinical experiment, and the authors think it meets the need of clinical diagnosis. Application of this system in γ cameras can provide whole body scan function at low cost

Usefulness of Thallium Scan for Differential Diagnosis of Breast Mass

Energy Technology Data Exchange (ETDEWEB)

Bae, Sang Kyun; Yum, Ha Yong; Lee, Chung Han; Choi, Kyung Hyun [Kosin University College of Medicine, Pusan (Korea, Republic of)

1994-07-15

The purpose of this study is to evaluate thallium scanning as a potential test in differentiating malignant from benign lesions of breast. Thirty-one female patients underwent thallium scan of the breast. After intravenous injection of 74-111 MBq(2-3 mCi)of thallium-201, anterior and lateral images were obtained. We compared thallium scans with pathological results. Of 11 patients with breast cancers, 10 cases (90.9%) were detected using thallium scan. Thallium scan obtained in one patient who had breast cancer but received several cycles of chemotherapy did not show thallium uptake. The smallest detectable cancer was 1.5 cm in diameter. In contrast, there is no thallium accumulation in breasts of 17 of 20 patients with benign disease (85%), Three cases of 13 fibrocystic disease show thallium uptake in their breast. In conclusion, thallium scan is an effective test in differentiating benign from malignant lesion.

Usefulness of Thallium Scan for Differential Diagnosis of Breast Mass

International Nuclear Information System (INIS)

Bae, Sang Kyun; Yum, Ha Yong; Lee, Chung Han; Choi, Kyung Hyun

1994-01-01

The purpose of this study is to evaluate thallium scanning as a potential test in differentiating malignant from benign lesions of breast. Thirty-one female patients underwent thallium scan of the breast. After intravenous injection of 74-111 MBq(2-3 mCi)of thallium-201, anterior and lateral images were obtained. We compared thallium scans with pathological results. Of 11 patients with breast cancers, 10 cases (90.9%) were detected using thallium scan. Thallium scan obtained in one patient who had breast cancer but received several cycles of chemotherapy did not show thallium uptake. The smallest detectable cancer was 1.5 cm in diameter. In contrast, there is no thallium accumulation in breasts of 17 of 20 patients with benign disease (85%), Three cases of 13 fibrocystic disease show thallium uptake in their breast. In conclusion, thallium scan is an effective test in differentiating benign from malignant lesion.

Using Priors to Compensate Geometrical Problems in Head-Mounted Eye Trackers

DEFF Research Database (Denmark)

Batista Narcizo, Fabricio; Ahmed, Zaheer; Hansen, Dan Witzner

The use of additional information (a.k.a. priors) to help the eye tracking process is presented as an alternative to compensate classical geometrical problems in head-mounted eye trackers. Priors can be obtained from several distinct sources, such as: sensors to collect information related...... estimation specially for uncalibrated head-mounted setups....

Nuclear scanning in necrotizing progressive ''malignant'' external otitis

International Nuclear Information System (INIS)

Parisier, S.C.; Lucente, F.E.; Som, P.M.; Hirschman, S.Z.; Arnold, L.M.; Roffman, J.D.

1982-01-01

The usefulness of radionuclear scanning in the treatment of 18 patients with necrotizing progressive ''malignant'' external otitis is discussed. A Tc 99-m bone scan, a valuable test since results are positive in early cases of osteomyelitis of the temporal bone and base of skull, showed increased uptake in all 18 patients. In 6 patients, Ga-67 citrate scans were obtained at the start of therapy and at 5-6 week intervals thereafter. The serial gallium scans were useful in evaluating the effectiveness of therapy since the uptake decrease with control of infection

Investigation into scanning tunnelling luminescence microscopy

International Nuclear Information System (INIS)

Manson-Smith, S.K.

2001-01-01

This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provide information on recombination processes and material properties. The design and construction of a scanning tunnelling luminescence microscope is described in detail. Operating under ambient conditions, the microscope has several novel features, including a new type of miniature inertial slider-based approach motor, large solid-angle light collection optical arrangement and a tip-height regulation system which requires the minimum of operator input. (author)

Confocal scanning microscopy with multiple optical probes for high speed measurements and better imaging

Science.gov (United States)

Chun, Wanhee; Lee, SeungWoo; Gweon, Dae-Gab

2008-02-01

Confocal scanning microscopy (CSM) needs a scanning mechanism because only one point information of specimen can be obtained. Therefore the speed of the confocal scanning microscopy is limited by the speed of the scanning tool. To overcome this limitation from scanning tool we propose another scanning mechanism. We make three optical probes in the specimen under confocal condition of each point. Three optical probes are moved by beam scanning mechanism with shared resonant scanning mirror (RM) and galvanometer driven mirror (GM). As each optical probe scan allocated region of the specimen, information from three points is obtained simultaneously and image acquisition time is reduced. Therefore confocal scanning microscopy with multiple optical probes is expected to have three times faster speed of the image acquisition than conventional one. And as another use, multiple optical probes to which different light wavelength is applied can scan whole same region respectively. It helps to obtain better contrast image in case of specimens having different optical characteristics for specific light wavelength. In conclusion confocal scanning microscopy with multiple optical probes is useful technique for views of image acquisition speed and image quality.

Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery

Directory of Open Access Journals (Sweden)

Paoli Alessandro

2011-02-01

Full Text Available Abstract Background A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides. Methods In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast and preoperative (radiographic template models, obtained by both CT and optical scanning processes. Results A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates. Conclusions The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology.

Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery

Science.gov (United States)

2011-01-01

Background A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides. Methods In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes. Results A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates. Conclusions The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology. PMID:21338504

Magnetic scanning of LWR fuel assemblies

International Nuclear Information System (INIS)

Fiarman, S.; Moodenbaugh, A.

1980-01-01

Nondestructive assay (NDA) techniques are available both for fresh and spent fuel, but generally are too time consuming and do not uniquely identify an assembly. A new method is reported to obtain a signature from a magnetic scan of each assembly. This scan is an NDA technique that detects magnetic inclusions. It is potentially fast (5 min/assembly), and may provide a unique signature from the magnetic properties of each fuel assembly

A study on repainting strategies for treating moderately moving targets with proton pencil beam scanning at the new Gantry 2 at PSI

International Nuclear Information System (INIS)

Zenklusen, S M; Pedroni, E; Meer, D

2010-01-01

Treating moving targets using a scanning gantry for proton therapy is a promising but very challenging, not yet clinically demonstrated treatment modality. The interference of organ motion with the sequence of the beam delivery produces uncontrolled dose inhomogeneities within the target. One promising approach to overcome this difficulty is to increase the speed of scanning in order to apply the dose repeatedly (so-called repainting). To obtain sufficiently high scanning speeds a new, technologically improved gantry-Gantry 2-has been designed and is currently under construction at PSI. As there are many possible repainting strategies, the way repainting will be implemented on Gantry 2 will depend on the result of a careful analysis of the various treatment delivery strategies available. To achieve this aim, and prior to the start of experimental work with Gantry 2, simulations of dose distribution errors due to organ motion under various beam delivery strategies were investigated. The effects of motion on the dose distribution were studied for moderate motion amplitudes (5 mm) for spherical target volumes in a homogeneous medium and with homogeneous dose. In total over 200 000 dose distributions have been simulated and analyzed and selected results are discussed. From the obtained results we are confident to be able to treat moderately moving targets on Gantry 2 using repainted pencil-beam spot scanning. Continuous line scanning seems to be the most elegant solution; it provides higher repainting rates and produces superior results but is probably more difficult to realize. For larger motion amplitudes, continuous line scanning still shows good results, but we plan anyways to use a gating system for these cases, not only to reduce the inhomogeneity within the target volume but also to reduce safety margins.

A Radiological Survey Approach to Use Prior to Decommissioning: Results from a Technology Scanning and Assessment Project Focused on the Chornobyl NPP

Energy Technology Data Exchange (ETDEWEB)

Milchikov, A.; Hund, G.; Davidko, M.

1999-10-20

The primary objectives of this project are to learn how to plan and execute the Technology Scanning and Assessment (TSA) approach by conducting a project and to be able to provide the approach as a capability to the Chernobyl Nuclear Power Plant (ChNPP) and potentially elsewhere. A secondary objective is to learn specifics about decommissioning and in particular about radiological surveying to be performed prior to decommissioning to help ChNPP decision makers. TSA is a multi-faceted capability that monitors and analyzes scientific, technical, regulatory, and business factors and trends for decision makers and company leaders. It is a management tool where information is systematically gathered, analyzed, and used in business planning and decision making. It helps managers by organizing the flow of critical information and provides managers with information they can act upon. The focus of this TSA project is on radiological surveying with the target being ChNPP's Unit 1. This reactor was stopped on November 30, 1996. At this time, Ukraine failed to have a regulatory basis to provide guidelines for nuclear site decommissioning. This situation has not changed as of today. A number of documents have been prepared to become a basis for a combined study of the ChNPP Unit 1 from the engineering and radiological perspectives. The results of such a study are expected to be used when a detailed decommissioning plan is created.

A Radiological Survey Approach to Use Prior to Decommissioning: Results from a Technology Scanning and Assessment Project Focused on the Chernobyl NPP

International Nuclear Information System (INIS)

Milchikov, A.; Hund, G.; Davidko, M.

1999-01-01

The primary objectives of this project are to learn how to plan and execute the Technology Scanning and Assessment (TSA) approach by conducting a project and to be able to provide the approach as a capability to the Chernobyl Nuclear Power Plant (ChNPP) and potentially elsewhere. A secondary objective is to learn specifics about decommissioning and in particular about radiological surveying to be performed prior to decommissioning to help ChNPP decision makers. TSA is a multi-faceted capability that monitors and analyzes scientific, technical, regulatory, and business factors and trends for decision makers and company leaders. It is a management tool where information is systematically gathered, analyzed, and used in business planning and decision making. It helps managers by organizing the flow of critical information and provides managers with information they can act upon. The focus of this TSA project is on radiological surveying with the target being ChNPP's Unit 1. This reactor was stopped on November 30, 1996. At this time, Ukraine failed to have a regulatory basis to provide guidelines for nuclear site decommissioning. This situation has not changed as of today. A number of documents have been prepared to become a basis for a combined study of the ChNPP Unit 1 from the engineering and radiological perspectives. The results of such a study are expected to be used when a detailed decommissioning plan is created

/sup 99m/Tc penicillamine: a renal cortical scanning agent

International Nuclear Information System (INIS)

Taylor, A.; Davis, G.; Halpern, S.; Ashburn, W.

1977-01-01

/sup 99m/Technetium penicillamine, a renal cortical imaging agent, can be used to provide a rapid, safe and non-invasive assessment of renal morphology and the renal vascular supply. Since this agent is not excreted significantly during the imaging procedure cortical scans of high quality can be obtained without image deterioration owing to a superimposed collecting system. These scans, which are clearly superior in anatomical detail to earlier scans using 131 I hippuran, can be obtained along with the 131 I hippuran renogram when the patient comes to the nuclear medicine department. Herein we demonstrate the anatomical detail it is now possible to achieve by presenting the cortical renal scans and accompanying radiograms from 5 patients with different renal pathology

[Accuracy of attenuation coefficient obtained by 137Cs single-transmission scanning in PET: comparison with conventional germanium line source].

Science.gov (United States)

Matsumoto, Keiichi; Kitamura, Keishi; Mizuta, Tetsuro; Shimizu, Keiji; Murase, Kenya; Senda, Michio

2006-02-20

Transmission scanning can be successfully performed with a Cs-137 single-photon-emitting point source for three-dimensional PET imaging. This method was effective for postinjection transmission scanning because of differences in physical energy. However, scatter contamination in the transmission data lowers measured attenuation coefficients. The purpose of this study was to investigate the accuracy of the influence of object scattering by measuring the attenuation coefficients on the transmission images. We also compared the results with the conventional germanium line source method. Two different types of PET scanner, the SET-3000 G/X (Shimadzu Corp.) and ECAT EXACT HR(+) (Siemens/CTI) , were used. For the transmission scanning, the SET-3000 G/X and ECAT HR(+) were the Cs-137 point source and Ge-68/Ga-68 line source, respectively. With the SET-3000 G/X, we performed transmission measurement at two energy gate settings, the standard 600-800 keV as well as 500-800 keV. The energy gate setting of the ECAT HR(+) was 350-650 keV. The effects of scattering in a uniform phantom with different cross-sectional areas ranging from 201 cm(2) to 314 cm(2) to 628 cm(2) (apposition of the two 20 cm diameter phantoms) and 943 cm(2) (stacking of the three 20 cm diameter phantoms) were acquired without emission activity. First, we evaluated the attenuation coefficients of the two different types of transmission scanning using region of interest (ROI) analysis. In addition, we evaluated the attenuation coefficients with and without segmentation for Cs-137 transmission images using the same analysis. The segmentation method was a histogram-based soft-tissue segmentation process that can also be applied to reconstructed transmission images. In the Cs-137 experiment, the maximum underestimation was 3% without segmentation, which was reduced to less than 1% with segmentation at the center of the largest phantom. In the Ge-68/Ga-68 experiment, the difference in mean attenuation

Accuracy of attenuation coefficient obtained by 137Cs single-transmission scanning in PET. Comparison with conventional germanium line source

International Nuclear Information System (INIS)

Matsumoto, Keiichi; Shimizu, Keiji; Senda, Michio; Kitamura, Keishi; Mizuta, Tetsuro; Murase, Kenya

2006-01-01

Transmission scanning can be successfully performed with a Cs-137 single-photon-emitting point source for three-dimensional PET imaging. This method was effective for postinjection transmission scanning because of differences in physical energy. However, scatter contamination in the transmission data lowers measured attenuation coefficients. The purpose of this study was to investigate the accuracy of the influence of object scattering by measuring the attenuation coefficients on the transmission images. We also compared the results with the conventional germanium line source method. Two different types of PET scanner, the SET-3000 G/X (Shimadzu Corp.) and ECAT EXACT HR + (Siemens/CTI), were used. For the transmission scanning, the SET-3000 G/X and ECAT HR + were the Cs-137 point source and Ge-68/Ga-68 line source, respectively. With the SET-3000 G/X, we performed transmission measurement at two energy gate settings, the standard 600-800 keV as well as 500-800 keV. The energy gate setting of the ECAT HR 2 + was 350-650 keV. The effects of scattering in a uniform phantom with different cross-sectional areas ranging from 201 cm 2 to 314 cm 2 to 628 cm 2 (apposition of the two 20 cm diameter phantoms) and 943 cm 2 (stacking of the three 20 cm diameter phantoms) were acquired without emission activity. First, we evaluated the attenuation coefficients of the two different types of transmission scanning using region of interest (ROI) analysis. In addition, we evaluated the attenuation coefficients with and without segmentation for Cs-137 transmission images using the same analysis. The segmentation method was a histogram-based soft-tissue segmentation process that can also be applied to reconstructed transmission images. In the Cs-137 experiment, the maximum underestimation was 3% without segmentation, which was reduced to less than 1% with segmentation at the center of the largest phantom. In the Ge-68/Ga-68 experiment, the difference in mean attenuation coefficients

System and method for compressive scanning electron microscopy

Science.gov (United States)

Reed, Bryan W

2015-01-13

A scanning transmission electron microscopy (STEM) system is disclosed. The system may make use of an electron beam scanning system configured to generate a plurality of electron beam scans over substantially an entire sample, with each scan varying in electron-illumination intensity over a course of the scan. A signal acquisition system may be used for obtaining at least one of an image, a diffraction pattern, or a spectrum from the scans, the image, diffraction pattern, or spectrum representing only information from at least one of a select subplurality or linear combination of all pixel locations comprising the image. A dataset may be produced from the information. A subsystem may be used for mathematically analyzing the dataset to predict actual information that would have been produced by each pixel location of the image.

External Prior Guided Internal Prior Learning for Real-World Noisy Image Denoising

Science.gov (United States)

Xu, Jun; Zhang, Lei; Zhang, David

2018-06-01

Most of existing image denoising methods learn image priors from either external data or the noisy image itself to remove noise. However, priors learned from external data may not be adaptive to the image to be denoised, while priors learned from the given noisy image may not be accurate due to the interference of corrupted noise. Meanwhile, the noise in real-world noisy images is very complex, which is hard to be described by simple distributions such as Gaussian distribution, making real noisy image denoising a very challenging problem. We propose to exploit the information in both external data and the given noisy image, and develop an external prior guided internal prior learning method for real noisy image denoising. We first learn external priors from an independent set of clean natural images. With the aid of learned external priors, we then learn internal priors from the given noisy image to refine the prior model. The external and internal priors are formulated as a set of orthogonal dictionaries to efficiently reconstruct the desired image. Extensive experiments are performed on several real noisy image datasets. The proposed method demonstrates highly competitive denoising performance, outperforming state-of-the-art denoising methods including those designed for real noisy images.

Detecting damage in steel with scanning SQUID microscopy

International Nuclear Information System (INIS)

Lee, Tae-Kyu; Clatterbuck, D.M.; Morris, J.W. Jr.; Shaw, T.J.; Lee, Seungkyun; Clarke, John

2002-01-01

A 'Holy Grail' of NDE research is a non-destructive method for measuring fatigue damage prior to crack initiation. High-Tc scanning SQUID microscopy may be a useful tool. Because of the exceptional magnetic sensitivity of this technique, fatigue damage can be detected well before microcrack initiation, and in the absence of other obvious microstructure or property changes. Given the spatial resolution of the technique, undamaged material can be located and used to set internal standards

Detecting damage in steel with scanning SQUID microscopy

International Nuclear Information System (INIS)

Lee, Tae-Kyu; Clatterbuck, David; Morris Jr., J.W.; Shaw, T.J.; McDermott R.; Clarke, John

2001-01-01

A ''Holy Grail'' of NDE research is a non-destructive method for measuring fatigue damage prior to crack initiation. High-Tc scanning SQUID microscopy may be a useful tool. Because of the exceptional magnetic sensitivity of this technique, fatigue damage can be detected well before microcrack initiation, and in the absence of other obvious microstructure or property changes. Given the spatial resolution of the technique, undamaged material can be located and used to set internal standards

Investigation into alternative sludge conditioning prior to dewatering

CSIR Research Space (South Africa)

Smollen, M

1997-01-01

Full Text Available have proven that the mixture of char and a small quantity of polyelectrolyte (0.5 to 1kg per ton of dry solids), used as a conditioner prior to centrifugation and filtration tests, produced cake solids concentration superior to that obtained by using...

Scanning Microscopes Using X Rays and Microchannels

Science.gov (United States)

Wang, Yu

2003-01-01

Scanning microscopes that would be based on microchannel filters and advanced electronic image sensors and that utilize x-ray illumination have been proposed. Because the finest resolution attainable in a microscope is determined by the wavelength of the illumination, the xray illumination in the proposed microscopes would make it possible, in principle, to achieve resolutions of the order of nanometers about a thousand times as fine as the resolution of a visible-light microscope. Heretofore, it has been necessary to use scanning electron microscopes to obtain such fine resolution. In comparison with scanning electron microscopes, the proposed microscopes would likely be smaller, less massive, and less expensive. Moreover, unlike in scanning electron microscopes, it would not be necessary to place specimens under vacuum. The proposed microscopes are closely related to the ones described in several prior NASA Tech Briefs articles; namely, Miniature Microscope Without Lenses (NPO-20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43; and Reflective Variants of Miniature Microscope Without Lenses (NPO-20610), NASA Tech Briefs, Vol. 26, No. 9 (September 2002) page 6a. In all of these microscopes, the basic principle of design and operation is the same: The focusing optics of a conventional visible-light microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. A microchannel plate containing parallel, microscopic-cross-section holes much longer than they are wide is placed between a specimen and an image sensor, which is typically the CCD. The microchannel plate must be made of a material that absorbs the illuminating radiation reflected or scattered from the specimen. The microchannels must be positioned and dimensioned so that each one is registered with a pixel on the image sensor. Because most of the radiation incident on the microchannel walls becomes absorbed, the radiation that reaches the

Detection and characterization of Budd-Chiari syndrome with inferior vena cava obstruction: Comparison of fixed and flexible delayed scan time of computed tomography venography.

Science.gov (United States)

Zhou, Peng-Li; Wu, Gang; Han, Xin-Wei; Bi, Yong-Hua; Zhang, Wen-Guang; Wu, Zheng-Yang

2017-06-01

To compare the results of computed tomography venography (CTV) with a fixed and a flexible delayed scan time for Budd-Chiari syndrome (BCS) with inferior vena cava (IVC) obstruction. A total of 209 consecutive BCS patients with IVC obstruction underwent either a CTV with a fixed delayed scan time of 180s (n=87) or a flexible delayed scan time for good image quality according to IVC blood flow in color Doppler ultrasonography (n=122). The IVC blood flow velocity was measured using a color Doppler ultrasound prior to CT scan. Image quality was classified as either good, moderate, or poor. Image quality, surrounding structures and the morphology of the IVC obstruction were compared between the two groups using a χ 2 -test or paired or unpaired t-tests as appropriate. Inter-observer agreement was assessed using Kappa statistics. There was no significant difference in IVC blood flow velocity between the two groups. Overall image quality, surrounding structures and IVC obstruction morphology delineation on the flexible delayed scan time of CTV images were rated better relative to those obtained by fixed delayed scan time of CTV images (ptime of CTV. There were no significant differences in Kappa statistics between Group A and Group B. The flexible delayed scan time of CTV was associated with better detection and more reliable characterization of BCS with IVC obstruction compared to a fixed delayed scan time. Copyright © 2017 Elsevier B.V. All rights reserved.

PET reconstruction via nonlocal means induced prior.

Science.gov (United States)

Hou, Qingfeng; Huang, Jing; Bian, Zhaoying; Chen, Wufan; Ma, Jianhua

2015-01-01

The traditional Bayesian priors for maximum a posteriori (MAP) reconstruction methods usually incorporate local neighborhood interactions that penalize large deviations in parameter estimates for adjacent pixels; therefore, only local pixel differences are utilized. This limits their abilities of penalizing the image roughness. To achieve high-quality PET image reconstruction, this study investigates a MAP reconstruction strategy by incorporating a nonlocal means induced (NLMi) prior (NLMi-MAP) which enables utilizing global similarity information of image. The present NLMi prior approximates the derivative of Gibbs energy function by an NLM filtering process. Specially, the NLMi prior is obtained by subtracting the current image estimation from its NLM filtered version and feeding the residual error back to the reconstruction filter to yield the new image estimation. We tested the present NLMi-MAP method with simulated and real PET datasets. Comparison studies with conventional filtered backprojection (FBP) and a few iterative reconstruction methods clearly demonstrate that the present NLMi-MAP method performs better in lowering noise, preserving image edge and in higher signal to noise ratio (SNR). Extensive experimental results show that the NLMi-MAP method outperforms the existing methods in terms of cross profile, noise reduction, SNR, root mean square error (RMSE) and correlation coefficient (CORR).

Classication Methods for CT-Scanned Carcass Midsections

DEFF Research Database (Denmark)

Skytte, Jacob Lercke; Dahl, Anders Lindbjerg; Larsen, Rasmus

2011-01-01

Computed tomography (CT) has successfully been applied in medical environments for decades. In recent years CT has also made its entry to the industrial environments, including the slaughterhouses. In this paper we investigate classication methods for an online CT system, in order to assist...... in the segmentation of the outer fat layer in the mid- section of CT-scanned pig carcasses. Prior information about the carcass composition can potentially be applied for a fully automated solution, in order to optimize the slaughter line. The methods comprise Markov Random Field and contextual Bayesian classication...

Virtual animation of victim-specific 3D models obtained from CT scans for forensic reconstructions: Living and dead subjects.

Science.gov (United States)

Villa, C; Olsen, K B; Hansen, S H

2017-09-01

Post-mortem CT scanning (PMCT) has been introduced at several forensic medical institutions many years ago and has proved to be a useful tool. 3D models of bones, skin, internal organs and bullet paths can rapidly be generated using post-processing software. These 3D models reflect the individual physiognomics and can be used to create whole-body 3D virtual animations. In such way, virtual reconstructions of the probable ante-mortem postures of victims can be constructed and contribute to understand the sequence of events. This procedure is demonstrated in two victims of gunshot injuries. Case #1 was a man showing three perforating gunshot wounds, who died due to the injuries of the incident. Whole-body PMCT was performed and 3D reconstructions of bones, relevant internal organs and bullet paths were generated. Using 3ds Max software and a human anatomy 3D model, a virtual animated body was built and probable ante-mortem postures visualized. Case #2 was a man presenting three perforating gunshot wounds, who survived the incident: one in the left arm and two in the thorax. Only CT scans of the thorax, abdomen and the injured arm were provided by the hospital. Therefore, a whole-body 3D model reflecting the anatomical proportions of the patient was made combining the actual bones of the victim with those obtained from the human anatomy 3D model. The resulted 3D model was used for the animation process. Several probable postures were also visualized in this case. It has be shown that in Case #1 the lesions and the bullet path were not consistent with an upright standing position; instead, the victim was slightly bent forward, i.e. he was sitting or running when he was shot. In Case #2, one of the bullets could have passed through the arm and continued into the thorax. In conclusion, specialized 3D modelling and animation techniques allow for the reconstruction of ante-mortem postures based on both PMCT and clinical CT. Copyright © 2017 Elsevier B.V. All rights

Valid MR imaging predictors of prior knee arthroscopy

International Nuclear Information System (INIS)

Discepola, Federico; Le, Huy B.Q.; Park, John S.; Clopton, Paul; Knoll, Andrew N.; Austin, Matthew J.; Resnick, Donald L.

2012-01-01

To determine whether fibrosis of the medial patellar reticulum (MPR), lateral patellar reticulum (LPR), deep medial aspect of Hoffa's fat pad (MDH), or deep lateral aspect of Hoffa's fat pad (LDH) is a valid predictor of prior knee arthroscopy. Institutional review board approval and waiver of informed consent were obtained for this HIPPA-compliant study. Initially, fibrosis of the MPR, LPR, MDH, or LDH in MR imaging studies of 50 patients with prior knee arthroscopy and 100 patients without was recorded. Subsequently, two additional radiologists, blinded to clinical data, retrospectively and independently recorded the presence of fibrosis of the MPR in 50 patients with prior knee arthroscopy and 50 without. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for detecting the presence of fibrosis in the MPR were calculated. κ statistics were used to analyze inter-observer agreement. Fibrosis of each of the regions examined during the first portion of the study showed a significant association with prior knee arthroscopy (p < 0.005 for each). A patient with fibrosis of the MPR, LDH, or LPR was 45.5, 9, or 3.7 times more likely, respectively, to have had a prior knee arthroscopy. Logistic regression analysis indicated that fibrosis of the MPR supplanted the diagnostic utility of identifying fibrosis of the LPR, LDH, or MDH, or combinations of these (p ≥ 0.09 for all combinations). In the second portion of the study, fibrosis of the MPR demonstrated a mean sensitivity of 82%, specificity of 72%, PPV of 75%, NPV of 81%, and accuracy of 77% for predicting prior knee arthroscopy. Analysis of MR images can be used to determine if a patient has had prior knee arthroscopy by identifying fibrosis of the MPR, LPR, MDH, or LDH. Fibrosis of the MPR was the strongest predictor of prior knee arthroscopy. (orig.)

Valid MR imaging predictors of prior knee arthroscopy

Energy Technology Data Exchange (ETDEWEB)

Discepola, Federico; Le, Huy B.Q. [McGill University Health Center, Jewsih General Hospital, Division of Musculoskeletal Radiology, Montreal, Quebec (Canada); Park, John S. [Annapolis Radiology Associates, Division of Musculoskeletal Radiology, Annapolis, MD (United States); Clopton, Paul; Knoll, Andrew N.; Austin, Matthew J.; Resnick, Donald L. [University of California San Diego (UCSD), Division of Musculoskeletal Radiology, San Diego, CA (United States)

2012-01-15

To determine whether fibrosis of the medial patellar reticulum (MPR), lateral patellar reticulum (LPR), deep medial aspect of Hoffa's fat pad (MDH), or deep lateral aspect of Hoffa's fat pad (LDH) is a valid predictor of prior knee arthroscopy. Institutional review board approval and waiver of informed consent were obtained for this HIPPA-compliant study. Initially, fibrosis of the MPR, LPR, MDH, or LDH in MR imaging studies of 50 patients with prior knee arthroscopy and 100 patients without was recorded. Subsequently, two additional radiologists, blinded to clinical data, retrospectively and independently recorded the presence of fibrosis of the MPR in 50 patients with prior knee arthroscopy and 50 without. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for detecting the presence of fibrosis in the MPR were calculated. {kappa} statistics were used to analyze inter-observer agreement. Fibrosis of each of the regions examined during the first portion of the study showed a significant association with prior knee arthroscopy (p < 0.005 for each). A patient with fibrosis of the MPR, LDH, or LPR was 45.5, 9, or 3.7 times more likely, respectively, to have had a prior knee arthroscopy. Logistic regression analysis indicated that fibrosis of the MPR supplanted the diagnostic utility of identifying fibrosis of the LPR, LDH, or MDH, or combinations of these (p {>=} 0.09 for all combinations). In the second portion of the study, fibrosis of the MPR demonstrated a mean sensitivity of 82%, specificity of 72%, PPV of 75%, NPV of 81%, and accuracy of 77% for predicting prior knee arthroscopy. Analysis of MR images can be used to determine if a patient has had prior knee arthroscopy by identifying fibrosis of the MPR, LPR, MDH, or LDH. Fibrosis of the MPR was the strongest predictor of prior knee arthroscopy. (orig.)

An empirical Bayes method for updating inferences in analysis of quantitative trait loci using information from related genome scans.

Science.gov (United States)

Zhang, Kui; Wiener, Howard; Beasley, Mark; George, Varghese; Amos, Christopher I; Allison, David B

2006-08-01

Individual genome scans for quantitative trait loci (QTL) mapping often suffer from low statistical power and imprecise estimates of QTL location and effect. This lack of precision yields large confidence intervals for QTL location, which are problematic for subsequent fine mapping and positional cloning. In prioritizing areas for follow-up after an initial genome scan and in evaluating the credibility of apparent linkage signals, investigators typically examine the results of other genome scans of the same phenotype and informally update their beliefs about which linkage signals in their scan most merit confidence and follow-up via a subjective-intuitive integration approach. A method that acknowledges the wisdom of this general paradigm but formally borrows information from other scans to increase confidence in objectivity would be a benefit. We developed an empirical Bayes analytic method to integrate information from multiple genome scans. The linkage statistic obtained from a single genome scan study is updated by incorporating statistics from other genome scans as prior information. This technique does not require that all studies have an identical marker map or a common estimated QTL effect. The updated linkage statistic can then be used for the estimation of QTL location and effect. We evaluate the performance of our method by using extensive simulations based on actual marker spacing and allele frequencies from available data. Results indicate that the empirical Bayes method can account for between-study heterogeneity, estimate the QTL location and effect more precisely, and provide narrower confidence intervals than results from any single individual study. We also compared the empirical Bayes method with a method originally developed for meta-analysis (a closely related but distinct purpose). In the face of marked heterogeneity among studies, the empirical Bayes method outperforms the comparator.

Simultaneous emission and transmission scanning in positron emission tomography

International Nuclear Information System (INIS)

Satoh, Tomohiko; Tanaka, Kazumi; Kitamura, Keishi; Amano, Masaharu; Miura, Shuichi

2001-01-01

Examination by PET (positron emission tomography) scanning, following the dosage of 2-deoxy- 18 F fluoro-D-glucose (FDG), is positively utilized for the diagnosis of cancers, rather than for the purpose of studies. This is because the examination by FDG-PET (PET scanning following the dosage of FDG) ensures higher efficiency in discrimination of cancers, than conventional CT and PET. The method of whole body scanning by PET scanning following the dosage of FDG is effectively utilized not only for discrimination cancers, but also for determining the degree of malignancy of tumors and evaluating the methods of treatment of cancers. In conventional methods for examining the degree of malignancy of tumors and evaluating the methods of cancer treatment, it is necessary to correct for the gamma-ray attenuation, which requires a longer time for examination, increasing the physical and psychological pains of the patients. We have installed the simultaneous emission and transmission scanning capability into the HEADTOME-V of the Shimadzu SET-2000W Series positron emission tomographic scanning instruments, to establish an instrument that permits FDG-PET whole body scanning in actual clinical fields, with minimized physical and psychological pains of patients concerned, yet ensuring an outstandingly high examination efficiency. This report also presents some data obtained by this newly developed instrument and those obtained in practical applications. (author)

Assessment of prior image induced nonlocal means regularization for low-dose CT reconstruction: Change in anatomy.

Science.gov (United States)

Zhang, Hao; Ma, Jianhua; Wang, Jing; Moore, William; Liang, Zhengrong

2017-09-01

Repeated computed tomography (CT) scans are prescribed for some clinical applications such as lung nodule surveillance. Several studies have demonstrated that incorporating a high-quality prior image into the reconstruction of subsequent low-dose CT (LDCT) acquisitions can either improve image quality or reduce data fidelity requirements. Our proposed previous normal-dose image induced nonlocal means (ndiNLM) regularization method for LDCT is an example of such a method. However, one major concern with prior image based methods is that they might produce false information when the prior image and the current LDCT image show different structures (for example, if a lung nodule emerges, grows, shrinks, or disappears over time). This study aims to assess the performance of the ndiNLM regularization method in situations with change in anatomy. We incorporated the ndiNLM regularization into the statistical image reconstruction (SIR) framework for reconstruction of subsequent LDCT images. Because of its patch-based search mechanism, a rough registration between the prior image and the current LDCT image is adequate for the SIR-ndiNLM method. We assessed the performance of the SIR-ndiNLM method in lung nodule surveillance for two different scenarios: (a) the nodule was not found in a baseline exam but appears in a follow-up LDCT scan; (b) the nodule was present in a baseline exam but disappears in a follow-up LDCT scan. We further investigated the effect of nodule size on the performance of the SIR-ndiNLM method. We found that a relatively large search-window (e.g., 33 × 33) should be used for the SIR-ndiNLM method to account for misalignment between the prior image and the current LDCT image, and to ensure that enough similar patches can be found in the prior image. With proper selection of other parameters, experimental results with two patient datasets demonstrated that the SIR-ndiNLM method did not miss true nodules nor introduce false nodules in the lung nodule

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

Directory of Open Access Journals (Sweden)

Tobias Meier

2015-02-01

Full Text Available We describe an atomic force microscope (AFM for the characterization of self-sensing tunneling magnetoresistive (TMR cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm3 is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm3. In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers.

Facial recognition and laser surface scan: a pilot study

DEFF Research Database (Denmark)

Lynnerup, Niels; Clausen, Maja-Lisa; Kristoffersen, Agnethe May

2009-01-01

Surface scanning of the face of a suspect is presented as a way to better match the facial features with those of a perpetrator from CCTV footage. We performed a simple pilot study where we obtained facial surface scans of volunteers and then in blind trials tried to match these scans with 2D...... photographs of the faces of the volunteers. Fifteen male volunteers were surface scanned using a Polhemus FastSCAN Cobra Handheld Laser Scanner. Three photographs were taken of each volunteer's face in full frontal, profile and from above at an angle of 45 degrees and also 45 degrees laterally. Via special...

Bayesian optimal experimental design for priors of compact support

KAUST Repository

Long, Quan

2016-01-01

to account for the bounded domain of the uniform prior pdf of the parameters. The underlying Gaussian distribution is obtained in the spirit of the Laplace method, more precisely, the mode is chosen as the maximum a posteriori (MAP) estimate

Combining prior day contours to improve automated prostate segmentation

International Nuclear Information System (INIS)

Godley, Andrew; Sheplan Olsen, Lawrence J.; Stephans, Kevin; Zhao Anzi

2013-01-01

Purpose: To improve the accuracy of automatically segmented prostate, rectum, and bladder contours required for online adaptive therapy. The contouring accuracy on the current image guidance [image guided radiation therapy (IGRT)] scan is improved by combining contours from earlier IGRT scans via the simultaneous truth and performance level estimation (STAPLE) algorithm. Methods: Six IGRT prostate patients treated with daily kilo-voltage (kV) cone-beam CT (CBCT) had their original plan CT and nine CBCTs contoured by the same physician. Three types of automated contours were produced for analysis. (1) Plan: By deformably registering the plan CT to each CBCT and then using the resulting deformation field to morph the plan contours to match the CBCT anatomy. (2) Previous: The contour set drawn by the physician on the previous day CBCT is similarly deformed to match the current CBCT anatomy. (3) STAPLE: The contours drawn by the physician, on each prior CBCT and the plan CT, are deformed to match the CBCT anatomy to produce multiple contour sets. These sets are combined using the STAPLE algorithm into one optimal set. Results: Compared to plan and previous, STAPLE improved the average Dice's coefficient (DC) with the original physician drawn CBCT contours to a DC as follows: Bladder: 0.81 ± 0.13, 0.91 ± 0.06, and 0.92 ± 0.06; Prostate: 0.75 ± 0.08, 0.82 ± 0.05, and 0.84 ± 0.05; and Rectum: 0.79 ± 0.06, 0.81 ± 0.06, and 0.85 ± 0.04, respectively. The STAPLE results are within intraobserver consistency, determined by the physician blindly recontouring a subset of CBCTs. Comparing plans recalculated using the physician and STAPLE contours showed an average disagreement less than 1% for prostate D98 and mean dose, and 5% and 3% for bladder and rectum mean dose, respectively. One scan takes an average of 19 s to contour. Using five scans plus STAPLE takes less than 110 s on a 288 core graphics processor unit. Conclusions: Combining the plan and all prior days via

Huffman and linear scanning methods with statistical language models.

Science.gov (United States)

Roark, Brian; Fried-Oken, Melanie; Gibbons, Chris

2015-03-01

Current scanning access methods for text generation in AAC devices are limited to relatively few options, most notably row/column variations within a matrix. We present Huffman scanning, a new method for applying statistical language models to binary-switch, static-grid typing AAC interfaces, and compare it to other scanning options under a variety of conditions. We present results for 16 adults without disabilities and one 36-year-old man with locked-in syndrome who presents with complex communication needs and uses AAC scanning devices for writing. Huffman scanning with a statistical language model yielded significant typing speedups for the 16 participants without disabilities versus any of the other methods tested, including two row/column scanning methods. A similar pattern of results was found with the individual with locked-in syndrome. Interestingly, faster typing speeds were obtained with Huffman scanning using a more leisurely scan rate than relatively fast individually calibrated scan rates. Overall, the results reported here demonstrate great promise for the usability of Huffman scanning as a faster alternative to row/column scanning.

What Can Computed Tomography Scans of the Thorax Show after Breast Surgery?

Directory of Open Access Journals (Sweden)

Afsaneh Alikhassi

2016-06-01

Full Text Available Background: Postoperative breast abnormalities after breast conserving surgery or modified radical mastectomy are frequently overlooked and inaccurately assessed or reported using multidetector computed tomography (MDCT. These inaccurate results may have legal ramifications for the clinicians, cause patients avoidable anxiety, and lead to additional unnecessary diagnostic follow-up testing and costs.Methods: The patients with a history of breast cancer who had undergone breast-conserving surgery or modified radical mastectomy up to 6 months prior to undergoing a thoracic MDCT scan consented and enrolled in this study. These patients underwent a thoracic MDCT scan either because of respiratory or cardiac clinical symptoms or as part of breast cancer staging.Results: Forty women were included in this study. Different postoperative breast changes observed on thoracic MDCT scans including fibrous scar tissue, fat necrosis, seroma, abscess, hematoma, and recurrent and residual tumor were described.Conclusions: MDCT scans offer sufficient evidence in many postoperative cases to allow a confident diagnosis. General radiologists who review thoracic MDCT scans should know how to characterize breast lesions incidentally found on MDCT scans after breast surgeries. This information would enhance the value of the radiologist’s report for appropriate case management.

First results from the INTEGRAL galactic plane scans

DEFF Research Database (Denmark)

Winkler, C.; Gehrels, N.; Schonfelder, V.

2003-01-01

Scans of the Galactic plane performed at regular intervals constitute a key element of the guaranteed time observations of the INTEGRAL observing programme. These scans are done for two reasons: frequent monitoring of the Galactic plane in order to detect transient sources, and time resolved mapp...... mapping of the Galactic plane in continuum and diffuse line emission. This paper describes first results obtained from the Galactic plane scans executed so far during the early phase (Dec. 2002-May 2003) of the nominal mission.......Scans of the Galactic plane performed at regular intervals constitute a key element of the guaranteed time observations of the INTEGRAL observing programme. These scans are done for two reasons: frequent monitoring of the Galactic plane in order to detect transient sources, and time resolved...

A Study on Liver Scan using 113mIn Colloid

International Nuclear Information System (INIS)

Koh, Chang Soon; Rhee, Chong Hoen; Chang, Kochang; Hong, Chang Gi

1969-01-01

There have been reported numberous cases of liver scanning in use of 198 Au colloid by many investigators, however, one in use of 113m In colloid has not been reported as yet in this country. The dose of 113 mIn for high diagnostic value in examination of each organ was determined and the diagnostic interpretability of liver scanning with the use of 113m In was carefully evaluated in comparison with the results of the liver scanning by the conventionally applied radioisotope. The comparative study of both figures of liver scanning with the use of 113m In colloid and 198 Au colloid delivered following results:1) The liver uptake rate and clearance into peripheral blood were accentuated more in case of 113m In colloid than in case of 198 Au colloid. 2) The interpretability of space occupying lesion in liver scanning with 113m In was also superior to one with 198 Au. 3) The figure of liver scanning with 113m In colloid corresponds not always to the figure with 198 Au. This difference can be explained by difference of phagocytic ability of reticuloendothelial system within liver. 4) In the liver scanning with 113m In colloid, the spleen is also visualized even in normal examine. 5) In the cases of disturbed liver function, uptake is more decreased in use of 113m In colloid than in 198 Au, in the spleen, however, the way is contrary. 6) With use of 113m In colloid, the time required for scanning could be shortened in comparison with 198 Au. 7) The filtration of 113m In colloid for scanning prior to human administration gives an expectation for better scanning figure.

Colon distension and scan protocol for CT-colonography: an overview

NARCIS (Netherlands)

Boellaard, Thierry N.; de Haan, Margriet C.; Venema, Henk W.; Stoker, Jaap

2013-01-01

This article reviews two important aspects of CT-colonography, namely colonic distension and scan parameters. Adequate distension should be obtained to visualize the complete colonic lumen and optimal scan parameters should be used to prevent unnecessary radiation burden. For optimal distension,

Polycrystalline silicon carbide dopant profiles obtained through a scanning nano-Schottky contact

International Nuclear Information System (INIS)

Golt, M. C.; Strawhecker, K. E.; Bratcher, M. S.; Shanholtz, E. R.

2016-01-01

The unique thermo-electro-mechanical properties of polycrystalline silicon carbide (poly-SiC) make it a desirable candidate for structural and electronic materials for operation in extreme environments. Necessitated by the need to understand how processing additives influence poly-SiC structure and electrical properties, the distribution of lattice defects and impurities across a specimen of hot-pressed 6H poly-SiC processed with p-type additives was visualized with high spatial resolution using a conductive atomic force microscopy approach in which a contact forming a nano-Schottky interface is scanned across the sample. The results reveal very intricate structures within poly-SiC, with each grain having a complex core-rim structure. This complexity results from the influence the additives have on the evolution of the microstructure during processing. It was found that the highest conductivities localized at rims as well as at the interface between the rim and the core. The conductivity of the cores is less than the conductivity of the rims due to a lower concentration of dopant. Analysis of the observed conductivities and current-voltage curves is presented in the context of nano-Schottky contact regimes where the conventional understanding of charge transport to diode operation is no longer valid.

Polycrystalline silicon carbide dopant profiles obtained through a scanning nano-Schottky contact

Energy Technology Data Exchange (ETDEWEB)

Golt, M. C.; Strawhecker, K. E.; Bratcher, M. S. [U.S. Army Research Laboratory, WMRD, Aberdeen Proving Ground, Maryland 21005 (United States); Shanholtz, E. R. [ORISE, Belcamp, Maryland 21017 (United States)

2016-07-14

The unique thermo-electro-mechanical properties of polycrystalline silicon carbide (poly-SiC) make it a desirable candidate for structural and electronic materials for operation in extreme environments. Necessitated by the need to understand how processing additives influence poly-SiC structure and electrical properties, the distribution of lattice defects and impurities across a specimen of hot-pressed 6H poly-SiC processed with p-type additives was visualized with high spatial resolution using a conductive atomic force microscopy approach in which a contact forming a nano-Schottky interface is scanned across the sample. The results reveal very intricate structures within poly-SiC, with each grain having a complex core-rim structure. This complexity results from the influence the additives have on the evolution of the microstructure during processing. It was found that the highest conductivities localized at rims as well as at the interface between the rim and the core. The conductivity of the cores is less than the conductivity of the rims due to a lower concentration of dopant. Analysis of the observed conductivities and current-voltage curves is presented in the context of nano-Schottky contact regimes where the conventional understanding of charge transport to diode operation is no longer valid.

The Use of Self-scanned Silicon Photodiode Arrays for Astronomical Spectrophotometry

Science.gov (United States)

Cochran, A. L.

1984-01-01

The use of a Reticon self scanned silicon photodiode array for precision spectrophotometry is discussed. It is shown that internal errors are + or - 0.003 mag. Observations obtained with a photodiode array are compared with observations obtained with other types of detectors with agreement, from 3500 A to 10500 A, of 1%. The photometric properties of self scanned photodiode arrays are discussed. Potential pitfalls are given.

Spatially adapted augmentation of age-specific atlas-based segmentation using patch-based priors

Science.gov (United States)

Liu, Mengyuan; Seshamani, Sharmishtaa; Harrylock, Lisa; Kitsch, Averi; Miller, Steven; Chau, Van; Poskitt, Kenneth; Rousseau, Francois; Studholme, Colin

2014-03-01

One of the most common approaches to MRI brain tissue segmentation is to employ an atlas prior to initialize an Expectation- Maximization (EM) image labeling scheme using a statistical model of MRI intensities. This prior is commonly derived from a set of manually segmented training data from the population of interest. However, in cases where subject anatomy varies significantly from the prior anatomical average model (for example in the case where extreme developmental abnormalities or brain injuries occur), the prior tissue map does not provide adequate information about the observed MRI intensities to ensure the EM algorithm converges to an anatomically accurate labeling of the MRI. In this paper, we present a novel approach for automatic segmentation of such cases. This approach augments the atlas-based EM segmentation by exploring methods to build a hybrid tissue segmentation scheme that seeks to learn where an atlas prior fails (due to inadequate representation of anatomical variation in the statistical atlas) and utilize an alternative prior derived from a patch driven search of the atlas data. We describe a framework for incorporating this patch-based augmentation of EM (PBAEM) into a 4D age-specific atlas-based segmentation of developing brain anatomy. The proposed approach was evaluated on a set of MRI brain scans of premature neonates with ages ranging from 27.29 to 46.43 gestational weeks (GWs). Results indicated superior performance compared to the conventional atlas-based segmentation method, providing improved segmentation accuracy for gray matter, white matter, ventricles and sulcal CSF regions.

Socio-economic variation in CT scanning in Northern England, 1990-2002

Directory of Open Access Journals (Sweden)

Pearce Mark S

2012-01-01

Full Text Available Abstract Background Socio-economic status is known to influence health throughout life. In childhood, studies have shown increased injury rates in more deprived settings. Socio-economic status may therefore be related to rates of certain medical procedures, such as computed tomography (CT scans. This study aimed to assess socio-economic variation among young people having CT scans in Northern England between 1990 and 2002 inclusive. Methods Electronic data were obtained from Radiology Information Systems of all nine National Health Service hospital Trusts in the region. CT scan data, including sex, date of scan, age at scan, number and type of scans were assessed in relation to quintiles of Townsend deprivation scores, obtained from linkage of postcodes with census data, using χ2 tests and Spearman rank correlations. Results During the study period, 39,676 scans were recorded on 21,089 patients, with 38,007 scans and 19,485 patients (11344 male and 8132 female linkable to Townsend scores. The overall distributions of both scans and patients by quintile of Townsend deprivation scores were significantly different to the distributions of Townsend scores from the census wards included in the study (p Conclusions Social inequalities exist in the numbers of young people undergoing CT scans with those from deprived areas more likely to do so. This may reflect the rates of injuries in these individuals and implies that certain groups within the population may receive higher radiation doses than others due to medical procedures.

Evaluation of 111In leukocyte whole body scanning

International Nuclear Information System (INIS)

McDougall, I.R.; Baumert, J.E.; Lantieri, R.L.

1979-01-01

Indium-111 oxine, polymorphonuclear cells isolated and labeled with 111 In were used for studying abscesses and inflammatory conditions. There were 64 total scans done in 59 patients, 32 male and 27 female, aged 3 to 81 years (average, 51). The original clinical diagnosis was abscess in 33 patients. The whole blood cell scan was abnormal in 12 (36%) of these, and a good clinical correlation was obtained in 11 of the 12. In the 21 with a normal scan, 18 had no evidence of abscess, yielding one false-positive and three false-negative interpretations in the abscess group. Thirteen patients had fever of unknown origin, nine had negative scans and no subsequent evidence of abscess, and four had positive scans with good correlation in three. Acute bone and joint infections were positive on scan (4/4), whereas chronic osteomyelitis was negative (0/2). Three patients with acute myocardial infarction and three of four with subacute bacterial endocarditis had normal scans. All three studies in renal transplant rejection showed positive uptake in the pelvic kidneys. Indium-111 white blood cell scans have proved useful to diagnose or exclude a diagnosis of abscess or inflammatory condition infiltrated with polymorphonuclear leukocytes

Cooling system for baby EBM scanning device

International Nuclear Information System (INIS)

Abd Halim Baijan; Muhammad Zahidee Taat; Abu Bakar Ghazali; Mohd Rizal Md Chulan; Rokiah Mohd Sabri; Leo Kwee Wah; Mohd Rizal Ibrahim; Lojius Lombigit; Azaman Ahmad

2009-01-01

Heat exchange of the scanning window of baby EBM is a critical factor for maintaining the integrity of the window material structure. As the titanium foil which was used as the scanning window, the maximum temperature accepted for the foil should be 200 degree C. This paper will discuss a simple method of Bernoulli principle to obtain the correct air blower capacity in order to reduce the heat of the scanning window of Baby EBM. It was found that the required air pressure and air speed of the blower are 2613.6 Pascal and 237.6 m3/h respectively for the electron accelerator of 0.14 MeV energy and 10 mA beam current. (Author)

Bone Marrow Scans with Colloidal {sup 198}Au

Energy Technology Data Exchange (ETDEWEB)

Chang, Sung Soo; Whang, Kee Suk [Kyungpook National University College of Medicine, Daegu (Korea, Republic of)

1973-03-15

The bone marrow scans with colloidal {sup 198}Au were performed on 33 cases with hematologically normal patients and patients with various blood dyscrasia. Bone marrow aspirations were done at iliac crest in all cases but one. A correlation between the scan findings and an erythroid cellularity was evaluated. The following results were obtained. 1) Out of 33 cases, 23 (about 70%) showed a correlation between {sup 198}Au marrow uptakes on the scans and the erythroid cellularity. 2) The diseases in which no correlation existed between {sup 198}Au uptake and erythroid cellularity were aplastic anemia, acute leukemia and chronic myelogenous leukemia.

Influence of PET/CT-introduction on PET scanning frequency and indications. Results of a multicenter study

International Nuclear Information System (INIS)

Stergar, H.; Bockisch, A.; Eschmann, S.M.; Krause, B.J.; Roedel, R.; Tiling, R.; Weckesser, M.

2007-01-01

Aim: to evaluate the influence of the introduction of combined PET/CT scanners into clinical routine. This investigation addresses the quantitative changes between PET/CT and stand alone PET. Methods: the study included all examinations performed on stand alone PET- or PET/CT-scanners within 12 month prior to and after implementation of PET/CT. The final data analysis included five university hospitals and a total number of 15 497 exams. We distinguished exams on stand alone tomographs prior to and after installation of the combined device as well as PET/CT scans particularly with regard to disease entities. Various further parameters were investigated. Results: the overall number of PET scans (PET and PET/CT) rose by 146% while the number of scans performed on stand alone scanners declined by 22%. Only one site registered an increase in stand alone PET. The number of exams for staging in oncology increased by 196% while that of cardiac scans decreased by 35% and the number of scans in neurology rose by 47%. The use of scans for radiotherapy planning increased to 7% of all PET/CT studies. The increase of procedures for so-called classic PET oncology indications was moderate compared to the more common tumors. An even greater increase was observed in some rare entities. Conclusions: the introduction of PET/CT led to more than a doubling of overall PET procedures with a main focus on oncology. Some of the observed changes in scanning frequency may be caused by a rising availability of new radiotracers and advancements of competing imaging methods. Nevertheless the evident increase in the use of PET/CT for the most common tumour types demonstrates its expanding role in cancer staging. The combination of molecular and morphologic imaging has not only found its place but is still gaining greater importance with new developments in technology and radiochemistry. (orig.)

A first order approximation of the tumor absorbed dose prior to treatment with Sr-89

International Nuclear Information System (INIS)

Manetou, A.; Toubanakis, N.; Lyra, M.; Lymouris, G.

1994-01-01

A new technique developed for the estimation of the absorbed dose prior to treatment with Sr-89 is presented. This technique implies that patient undergoes bone scanning with Tc-99m-MDP, two days before the administration of Sr-89. A number of sequential quantitative images are to be obtained over the first 8 hours after the Tc-99m-MDP injection and data are used to derive St-89 time retention curve. For the development of this technique a simplified model for the kinetics of both Sr-89 and Tc-99m-MDP was assumed. Data on the time retention of the two radiopharmaceuticals for a compartment including bone surface and bone space of trabecular and cortical bone for normal adults were combined together. A linear relationship was derived between the time required for the same percentage uptake of the two radiopharmaceuticals after single injection. The absorbed dose in the principal metastases and normal bone, of the same type and volume with the metastases, for two patients who were treated with Sr-89 for metastasized prostatic carcinoma are reported. (authors)

A scan statistic for continuous data based on the normal probability model

Directory of Open Access Journals (Sweden)

Huang Lan

2009-10-01

Full Text Available Abstract Temporal, spatial and space-time scan statistics are commonly used to detect and evaluate the statistical significance of temporal and/or geographical disease clusters, without any prior assumptions on the location, time period or size of those clusters. Scan statistics are mostly used for count data, such as disease incidence or mortality. Sometimes there is an interest in looking for clusters with respect to a continuous variable, such as lead levels in children or low birth weight. For such continuous data, we present a scan statistic where the likelihood is calculated using the the normal probability model. It may also be used for other distributions, while still maintaining the correct alpha level. In an application of the new method, we look for geographical clusters of low birth weight in New York City.

Role of bone scan in rheumatic disease

International Nuclear Information System (INIS)

Choi, Yun Young

2003-01-01

Rheumatic diseases can be categorized by pathology into several specific types of musculoskeletal problems, including synovitis (e.g. rheumatoid arthritis), enthesopathy (e.g. ankylosing spondylitis) and cartilage degeneration (e.g. osteoarthritis). Skeletal radiographs have contributed to the diagnosis of these articular diseases, and some disease entities need typical radiographic changes as a factor of the diagnostic criteria. However, they sometimes show normal radiographic findings in the early stage of disease, when there is demineralization of less than 30-50%. Bone scans have also been used in arthritis, but not widely because the findings are nonspecific and it is thought that bone scans do not add significant information to routine radiography. Bone scans do however play a different role than simple radiography, and it is a complementary imaging method in the course of management of arthritis. The image quality of bone scans can be improved by obtaining regional views and images under al pin-hole collimator, and through a variety of scintigraphic techniques including the three phase bone scan and bone SPECT. Therefore, bone scans could improve the diagnostic value, and answer multiple clinical questions, based on the pathophysiology of various forms of arthritis

Bone scanning as a routine examination of patients with mammary carcinoma; a critical consideration

International Nuclear Information System (INIS)

Heslinga, J.M.; Pauwels, E.K.J.; Zwaveling, A.

1982-01-01

The usefulness of bone scanning as a routine examination was evaluated in 136 female patients with mammary carcinoma of whom 81 were staged as Columbia A and 55 as Columbia B/C. The preoperative bone scanning was positive in only 4 patients (2.9%). Consequently, bone scanning is no longer performed in the authors clinic for the preoperative detection of skeletal metastases. Bone scanning as a routine examination at 6-month intervals does not appear to be useful for the first 4 years of the follow-up, either. Most of the patients with a positive bone scan displayed other signs of skeletal metastases at the same time, such as ostealgia and a raised serum alkaline phosphatase level. Further increase of the frequency of bone scanning during the follow-up period would increase the costs considerably, almost prohibitively, even apart from the question whether such a measure might indeed significantly influence the patient's prognosis. The authors conclude that bone scanning should only be performed on the basis of the anamnesis, physical and laboratory findings, both prior to operation and during the follow-up period. (Auth.)

Comparison of scatter rejection and low-contrast performance of scan equalization digital radiography (SEDR), slot-scan digital radiography, and full-field digital radiography systems for chest phantom imaging

International Nuclear Information System (INIS)

Liu Xinming; Shaw, Chris C.; Lai, Chao-Jen; Wang Tianpeng

2011-01-01

Purpose: To investigate and compare the scatter rejection properties and low-contrast performance of the scan equalization digital radiography (SEDR) technique to the slot-scan and conventional full-field digital radiography techniques for chest imaging. Methods: A prototype SEDR system was designed and constructed with an a-Se flat-panel (FP) detector to improve image quality in heavily attenuating regions of an anthropomorphic chest phantom. Slot-scanning geometry was used to reject scattered radiation without attenuating primary x rays. The readout scheme of the FP was modified to erase accumulated scatter signals prior to image readout. A 24-segment beam width modulator was developed to regulate x-ray exposures regionally and compensate for the low x-ray flux in heavily attenuating regions. To measure the scatter-to-primary ratios (SPRs), a 2 mm thick lead plate with a 2-D array of aperture holes was used to measure the primary signals, which were then subtracted from those obtained without the lead plate to determine scatter components. A 2-D array of aluminum beads (3 mm in diameter) was used as the low-contrast objects to measure the contrast ratios (CRs) and contrast-to-noise ratios (CNRs) for evaluating the low-contrast performance in chest phantom images. A set of two images acquired with the same techniques were subtracted from each other to measure the noise levels. SPRs, CRs, and CNRs of the SEDR images were measured in four anatomical regions of chest phantom images and compared to those of slot-scan images and full-field images acquired with and without antiscatter grid. Results: The percentage reduction of SPR (percentage of SPRs reduced with scatter removal/rejection methods relative to that for nongrid full-field imaging) averaged over four anatomical regions was measured to be 80%, 83%, and 71% for SEDR, slot-scan, and full-field with grid, respectively. The average CR over four regions was found to improve over that for nongrid full

Comparison of scatter rejection and low-contrast performance of scan equalization digital radiography (SEDR), slot-scan digital radiography, and full-field digital radiography systems for chest phantom imaging

Energy Technology Data Exchange (ETDEWEB)

Liu Xinming; Shaw, Chris C.; Lai, Chao-Jen; Wang Tianpeng [Department of Imaging Physics, Digital Imaging Research Laboratory, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009 (United States)

2011-01-15

Purpose: To investigate and compare the scatter rejection properties and low-contrast performance of the scan equalization digital radiography (SEDR) technique to the slot-scan and conventional full-field digital radiography techniques for chest imaging. Methods: A prototype SEDR system was designed and constructed with an a-Se flat-panel (FP) detector to improve image quality in heavily attenuating regions of an anthropomorphic chest phantom. Slot-scanning geometry was used to reject scattered radiation without attenuating primary x rays. The readout scheme of the FP was modified to erase accumulated scatter signals prior to image readout. A 24-segment beam width modulator was developed to regulate x-ray exposures regionally and compensate for the low x-ray flux in heavily attenuating regions. To measure the scatter-to-primary ratios (SPRs), a 2 mm thick lead plate with a 2-D array of aperture holes was used to measure the primary signals, which were then subtracted from those obtained without the lead plate to determine scatter components. A 2-D array of aluminum beads (3 mm in diameter) was used as the low-contrast objects to measure the contrast ratios (CRs) and contrast-to-noise ratios (CNRs) for evaluating the low-contrast performance in chest phantom images. A set of two images acquired with the same techniques were subtracted from each other to measure the noise levels. SPRs, CRs, and CNRs of the SEDR images were measured in four anatomical regions of chest phantom images and compared to those of slot-scan images and full-field images acquired with and without antiscatter grid. Results: The percentage reduction of SPR (percentage of SPRs reduced with scatter removal/rejection methods relative to that for nongrid full-field imaging) averaged over four anatomical regions was measured to be 80%, 83%, and 71% for SEDR, slot-scan, and full-field with grid, respectively. The average CR over four regions was found to improve over that for nongrid full

Line-scanning tomographic optical microscope with isotropic transfer function

International Nuclear Information System (INIS)

Gajdátsy, Gábor; Dudás, László; Erdélyi, Miklós; Szabó, Gábor

2010-01-01

An imaging method and optical system, referred to as a line-scanning tomographic optical microscope (LSTOM) using a combination of line-scanning technique and CT reconstruction principle, is proposed and studied theoretically and experimentally. In our implementation a narrow focus line is scanned over the sample and the reflected light is measured in a confocal arrangement. One such scan is equivalent to a transverse projection in tomography. Repeating the scanning procedure in several directions, a number of transverse projections are recorded from which the image can be obtained using conventional CT reconstruction algorithms. The resolution of the image is independent of the spatial dimensions and structure of the applied detector; furthermore, the transfer function of the system is isotropic. The imaging performance of the implemented confocal LSTOM was compared with a point-scanning confocal microscope, based on recorded images. These images demonstrate that the resolution of the confocal LSTOM exceeds (by 15%) the resolution limit of a point-scanning confocal microscope

Magnetic resonance imaging in evaluation of tunnel diameters prior to revision ACL reconstruction: a comparison to computed tomography

Energy Technology Data Exchange (ETDEWEB)

Drews, Bjoern Holger; Gulkin, Daniel; Guelke, Joachim; Gebhard, Florian [University of Ulm, Center of Surgery, Department for Orthopedic Trauma, Hand and Reconstructive Surgery, Ulm (Germany); Merz, Cornelia; Huth, Jochen; Mauch, Frieder [Sportklinik Stuttgart GmbH, Stuttgart (Germany)

2017-10-15

Revision ACL reconstruction is becoming more frequent because of a 10% rate of re-ruptures and insufficiencies. Currently, computed tomography (CT) represents the gold standard in detecting and measuring the tunnels of the initial ACL reconstruction. The purpose of this study was to compare measurement results of CT and thin-sliced MRI sequences, which were modified to a high soft tissue-bone contrast. Prior to an ACL revision surgery, 16 consecutive patients had an MRI in addition to the standard CT scan. A dedicated 0.25-T Esaote G-Scan (Esaote Biomedica, Cologne, Germany) with a Turbo 3D T1 sequence was used for MRI. Tunnel diameters were measured at 11 defined points of interest. For the statistical evaluation, the Mann-Whitney U test for connected samples was used. Inter- and intraobserver reliability was additionally calculated. All measured diameters showed significant to highly significant correlations between both diagnostic tools (r = 0.7-0.98). In addition, there was no significant difference (p > 0.5) between the two techniques. Almost all diameters showed nearly perfect intraobserver reliability (ICC 0.8-0.97). Interobserver reliability showed an ICC of 0.91/0.92 for only one diameter in MRI and CT. Prior to ACL revision surgery, bone tunnel measurements can be done using a 3D T1-MRI sequence in low-field MRI. MRI measurements show the same accuracy as CT scans. Preoperative radiation exposure in mainly young patients could be reduced. Also the costs of an additional CT scan could be saved. (orig.)

Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror.

Science.gov (United States)

Lu, Chen D; Kraus, Martin F; Potsaid, Benjamin; Liu, Jonathan J; Choi, Woojhon; Jayaraman, Vijaysekhar; Cable, Alex E; Hornegger, Joachim; Duker, Jay S; Fujimoto, James G

2013-12-20

We developed an ultrahigh speed, handheld swept source optical coherence tomography (SS-OCT) ophthalmic instrument using a 2D MEMS mirror. A vertical cavity surface-emitting laser (VCSEL) operating at 1060 nm center wavelength yielded a 350 kHz axial scan rate and 10 µm axial resolution in tissue. The long coherence length of the VCSEL enabled a 3.08 mm imaging range with minimal sensitivity roll-off in tissue. Two different designs with identical optical components were tested to evaluate handheld OCT ergonomics. An iris camera aided in alignment of the OCT beam through the pupil and a manual fixation light selected the imaging region on the retina. Volumetric and high definition scans were obtained from 5 undilated normal subjects. Volumetric OCT data was acquired by scanning the 2.4 mm diameter 2D MEMS mirror sinusoidally in the fast direction and linearly in the orthogonal slow direction. A second volumetric sinusoidal scan was obtained in the orthogonal direction and the two volumes were processed with a software algorithm to generate a merged motion-corrected volume. Motion-corrected standard 6 x 6 mm(2) and wide field 10 x 10 mm(2) volumetric OCT data were generated using two volumetric scans, each obtained in 1.4 seconds. High definition 10 mm and 6 mm B-scans were obtained by averaging and registering 25 B-scans obtained over the same position in 0.57 seconds. One of the advantages of volumetric OCT data is the generation of en face OCT images with arbitrary cross sectional B-scans registered to fundus features. This technology should enable screening applications to identify early retinal disease, before irreversible vision impairment or loss occurs. Handheld OCT technology also promises to enable applications in a wide range of settings outside of the traditional ophthalmology or optometry clinics including pediatrics, intraoperative, primary care, developing countries, and military medicine.

Trends and patterns of computed tomography scan use among children in The Netherlands: 1990-2012

Energy Technology Data Exchange (ETDEWEB)

Meulepas, Johanna M.; Gradowska, Patrycja; Kieft, Mariette; Hauptmann, Michael [Netherlands Cancer Institute, Department of Epidemiology and Biostatistics, Amsterdam (Netherlands); Smets, Anne M.J.B. [Academic Medical Center Amsterdam, Department of Radiology, Amsterdam (Netherlands); Nievelstein, Rutger A.J. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Verbeke, Jonathan [VU University Medical Center, Department of Radiology, Amsterdam (Netherlands); Holscher, Herma C. [HAGA Hospital/Juliana Children' s Hospital, Department of Radiology, The Hague (Netherlands); Rutten, Matthieu J.C.M. [Jeroen Bosch Hospital, Department of Radiology, ' s Hertogenbosch (Netherlands); Ronckers, Cecile M. [Academic Medical Center Amsterdam, Department of Paediatric Oncology Emma Children' s Hospital, Amsterdam (Netherlands)

2017-06-15

To evaluate trends and patterns in CT usage among children (aged 0-17 years) in The Netherlands during the period 1990-2012. Lists of electronically archived paediatric CT scans were requested from the Radiology Information Systems (RIS) of Dutch hospitals which reported >10 paediatric CT scans annually in a survey conducted in 2010. Data included patient identification, birth date, gender, scan date and body part scanned. For non-participating hospitals and for years prior to electronic archiving in some participating hospitals, data were imputed by calendar year and hospital type (academic, general with <500 beds, general with ≥ 500 beds). Based on 236,066 CT scans among 146,368 patients performed between 1990 and 2012, estimated annual numbers of paediatric CT scans in The Netherlands increased from 7,731 in 1990 to 26,023 in 2012. More than 70 % of all scans were of the head and neck. During the last decade, substantial increases of more than 5 % per year were observed in general hospitals with fewer than 500 beds and among children aged 10 years or older. The estimated number of paediatric CT scans has more than tripled in The Netherlands during the last two decades. (orig.)

Trends and patterns of computed tomography scan use among children in The Netherlands: 1990-2012

International Nuclear Information System (INIS)

Meulepas, Johanna M.; Gradowska, Patrycja; Kieft, Mariette; Hauptmann, Michael; Smets, Anne M.J.B.; Nievelstein, Rutger A.J.; Verbeke, Jonathan; Holscher, Herma C.; Rutten, Matthieu J.C.M.; Ronckers, Cecile M.

2017-01-01

To evaluate trends and patterns in CT usage among children (aged 0-17 years) in The Netherlands during the period 1990-2012. Lists of electronically archived paediatric CT scans were requested from the Radiology Information Systems (RIS) of Dutch hospitals which reported >10 paediatric CT scans annually in a survey conducted in 2010. Data included patient identification, birth date, gender, scan date and body part scanned. For non-participating hospitals and for years prior to electronic archiving in some participating hospitals, data were imputed by calendar year and hospital type (academic, general with <500 beds, general with ≥ 500 beds). Based on 236,066 CT scans among 146,368 patients performed between 1990 and 2012, estimated annual numbers of paediatric CT scans in The Netherlands increased from 7,731 in 1990 to 26,023 in 2012. More than 70 % of all scans were of the head and neck. During the last decade, substantial increases of more than 5 % per year were observed in general hospitals with fewer than 500 beds and among children aged 10 years or older. The estimated number of paediatric CT scans has more than tripled in The Netherlands during the last two decades. (orig.)

Dual purpose QA tool developed for teletherapy unit and CT scan in SNDH

International Nuclear Information System (INIS)

Shilvant, D.V.; Tamane, C.J.; Pangam, S.B.; Raees, M.D.; Aynoor, S.K.; Pol, P.S.; Verghese, Aju; Ghorpade, C.J.

2007-01-01

To make a simple device used in Teletherapy unit and CT scan for depth data measurement. The accurate depth data is essential and very important factor for precise treatment in SAD isocentric setup calculation. In CT scan based treatment planning, the calculation obtained is from the depth given by the CT scan. The success of treatment depends on the same parameters in treatment unit matched with diagnostic CT scan data. To check the depth parameters in both CT scan and Teletherapy unit we have developed a single QA tool in our hospital. As this tool is precise, handy and easily accessible the results obtained from it assures the quality of Teletherapy unit as well as CT scan depth data. This small device resulted data helps a lot in calculations of complicated SAD setup in Telecobalt and also useful in recent new treatment modalities such as IMRT, micro MLC, etc

IMEF gamma scanning system

Energy Technology Data Exchange (ETDEWEB)

Baek, Sang Yeol; Park, Dae Kyu; Ahn, Sang Bok; Ju, Yong Sun; Jeon, Yong Bum

1997-06-01

The gamma scanning system which is installed in IMEF is the equipment obtaining the gamma ray spectrum from irradiated fuels. This equipment could afford the useful data relating spent fuels like as burn-up measurements. We describe the specifications of the equipment and its accessories, and also described its operation procedure so that an operator can use this report as the operation procedure. (author). 1 tab., 11 figs., 11 refs.

IMEF gamma scanning system

International Nuclear Information System (INIS)

Baek, Sang Yeol; Park, Dae Kyu; Ahn, Sang Bok; Ju, Yong Sun; Jeon, Yong Bum.

1997-06-01

The gamma scanning system which is installed in IMEF is the equipment obtaining the gamma ray spectrum from irradiated fuels. This equipment could afford the useful data relating spent fuels like as burn-up measurements. We describe the specifications of the equipment and its accessories, and also described its operation procedure so that an operator can use this report as the operation procedure. (author). 1 tab., 11 figs., 11 refs

Application of Laser Scanning for Creating Geological Documentation

Directory of Open Access Journals (Sweden)

Buczek Michał

2018-01-01

Full Text Available A geological documentation is based on the analyses obtained from boreholes, geological exposures, and geophysical methods. It consists of text and graphic documents, containing drilling sections, vertical crosssections through the deposit and various types of maps. The surveying methods (such as LIDAR can be applied in measurements of exposed rock layers, presented in appendices to the geological documentation. The laser scanning allows obtaining a complete profile of exposed surfaces in a short time and with a millimeter accuracy. The possibility of verifying the existing geological cross-section with laser scanning was tested on the example of the AGH experimental mine. The test field is built of different lithological rocks. Scans were taken from a single station, under favorable measuring conditions. The analysis of the signal intensity allowed to divide point cloud into separate geological layers. The results were compared with the geological profiles of the measured object. The same approach was applied to the data from the Vietnamese hard coal open pit mine Coc Sau. The thickness of exposed coal bed deposits and gangue layers were determined from the obtained data (point cloud in combination with the photographs. The results were compared with the geological cross-section.

A technique for estimating 4D-CBCT using prior knowledge and limited-angle projections

International Nuclear Information System (INIS)

Zhang, You; Yin, Fang-Fang; Ren, Lei; Segars, W. Paul

2013-01-01

Purpose: To develop a technique to estimate onboard 4D-CBCT using prior information and limited-angle projections for potential 4D target verification of lung radiotherapy.Methods: Each phase of onboard 4D-CBCT is considered as a deformation from one selected phase (prior volume) of the planning 4D-CT. The deformation field maps (DFMs) are solved using a motion modeling and free-form deformation (MM-FD) technique. In the MM-FD technique, the DFMs are estimated using a motion model which is extracted from planning 4D-CT based on principal component analysis (PCA). The motion model parameters are optimized by matching the digitally reconstructed radiographs of the deformed volumes to the limited-angle onboard projections (data fidelity constraint). Afterward, the estimated DFMs are fine-tuned using a FD model based on data fidelity constraint and deformation energy minimization. The 4D digital extended-cardiac-torso phantom was used to evaluate the MM-FD technique. A lung patient with a 30 mm diameter lesion was simulated with various anatomical and respirational changes from planning 4D-CT to onboard volume, including changes of respiration amplitude, lesion size and lesion average-position, and phase shift between lesion and body respiratory cycle. The lesions were contoured in both the estimated and “ground-truth” onboard 4D-CBCT for comparison. 3D volume percentage-difference (VPD) and center-of-mass shift (COMS) were calculated to evaluate the estimation accuracy of three techniques: MM-FD, MM-only, and FD-only. Different onboard projection acquisition scenarios and projection noise levels were simulated to investigate their effects on the estimation accuracy.Results: For all simulated patient and projection acquisition scenarios, the mean VPD (±S.D.)/COMS (±S.D.) between lesions in prior images and “ground-truth” onboard images were 136.11% (±42.76%)/15.5 mm (±3.9 mm). Using orthogonal-view 15°-each scan angle, the mean VPD/COMS between the lesion

Scanning-time evaluation of Digimarc Barcode

Science.gov (United States)

Gerlach, Rebecca; Pinard, Dan; Weaver, Matt; Alattar, Adnan

2015-03-01

This paper presents a speed comparison between the use of Digimarc® Barcodes and the Universal Product Code (UPC) for customer checkout at point of sale (POS). The recently introduced Digimarc Barcode promises to increase the speed of scanning packaged goods at POS. When this increase is exploited by workforce optimization systems, the retail industry could potentially save billions of dollars. The Digimarc Barcode is based on Digimarc's watermarking technology, and it is imperceptible, very robust, and does not require any special ink, material, or printing processes. Using an image-based scanner, a checker can quickly scan consumer packaged goods (CPG) embedded with the Digimarc Barcode without the need to reorient the packages with respect to the scanner. Faster scanning of packages saves money and enhances customer satisfaction. It reduces the length of the queues at checkout, reduces the cost of cashier labor, and makes self-checkout more convenient. This paper quantifies the increase in POS scanning rates resulting from the use of the Digimarc Barcode versus the traditional UPC. It explains the testing methodology, describes the experimental setup, and analyzes the obtained results. It concludes that the Digimarc Barcode increases number of items per minute (IPM) scanned at least 50% over traditional UPC.

Possible Laminographic and Tomosynthesis Applications for Wolter Microscope Scan Geometries

International Nuclear Information System (INIS)

Schneberk, D; Jackson, J; Martz, H

2004-01-01

systems. Figure 2 contains a picture of the Wolter optics geometry for inspection. Figure 3 contains an illustration of the scan geometry used in single-plane laminography for flat objects, while figure 4 contains a picture of the scan geometry and motion for a class of tomosynthesis algorithms. The Wolter transmission paths depicted in figure 2 are similar to laminographic and tomosynthesis paths and they provide opportunities to exploit either of these algorithms for removing out of plane blur from Wolter optic images. Other algorithms may arise from the sequence of images obtained by translation through the focus of the Wolter microscope. A variety of LLNL programs have developed iterative and semi-iterative schemes for utilizing prior knowledge from drawings, or other physical measurements to improve defect recognition and inspection of objects. One such algorithm would use the laminographic estimate of each plane as the first estimate of the object function, then iterate on the object function until the forward projections match the acquired sequence of projections translated through the focus of the Wolter microscope. Unlike the laminography and tomosynthesis approaches this particular approach requires a forward model of the projection through the object. We employed an LLNL developed Wolter simulation code [Jackson 2004] to evaluate possible scanning options since a working Wolter was not available. Six synthetic objects were formulated: (1) concentric spheres with a cylindrical void, (2) concentric spheres with a cylindrical inclusion, (3) a sphere with a number of successively smaller sphere-voids arranged in the mid-plane of the object, (4) a sphere with a number of successively smaller sphere inclusions arranged in the mid-plane of the object, (5) a slab object with voids at the entrance plane and at the exit plane of the thickness, and (6) a slab object with inclusions at the entrance plane and at the exit plane of the thickness. Of the six synthetic objects

Identification of subsurface structures using electromagnetic data and shape priors

Energy Technology Data Exchange (ETDEWEB)

Tveit, Svenn, E-mail: svenn.tveit@uni.no [Uni CIPR, Uni Research, Bergen 5020 (Norway); Department of Mathematics, University of Bergen, Bergen 5020 (Norway); Bakr, Shaaban A., E-mail: shaaban.bakr1@gmail.com [Department of Mathematics, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Uni CIPR, Uni Research, Bergen 5020 (Norway); Lien, Martha, E-mail: martha.lien@octio.com [Uni CIPR, Uni Research, Bergen 5020 (Norway); Octio AS, Bøhmergaten 44, Bergen 5057 (Norway); Mannseth, Trond, E-mail: trond.mannseth@uni.no [Uni CIPR, Uni Research, Bergen 5020 (Norway); Department of Mathematics, University of Bergen, Bergen 5020 (Norway)

2015-03-01

We consider the inverse problem of identifying large-scale subsurface structures using the controlled source electromagnetic method. To identify structures in the subsurface where the contrast in electric conductivity can be small, regularization is needed to bias the solution towards preserving structural information. We propose to combine two approaches for regularization of the inverse problem. In the first approach we utilize a model-based, reduced, composite representation of the electric conductivity that is highly flexible, even for a moderate number of degrees of freedom. With a low number of parameters, the inverse problem is efficiently solved using a standard, second-order gradient-based optimization algorithm. Further regularization is obtained using structural prior information, available, e.g., from interpreted seismic data. The reduced conductivity representation is suitable for incorporation of structural prior information. Such prior information cannot, however, be accurately modeled with a gaussian distribution. To alleviate this, we incorporate the structural information using shape priors. The shape prior technique requires the choice of kernel function, which is application dependent. We argue for using the conditionally positive definite kernel which is shown to have computational advantages over the commonly applied gaussian kernel for our problem. Numerical experiments on various test cases show that the methodology is able to identify fairly complex subsurface electric conductivity distributions while preserving structural prior information during the inversion.

Comparison of gallium-67 scanning, bronchoalveolar lavage, and serum angiotensin-converting enzyme levels in pulmonary sarcoidosis. Predicting response to therapy

International Nuclear Information System (INIS)

Baughman, R.P.; Fernandez, M.; Bosken, C.H.; Mantil, J.; Hurtubise, P.

1984-01-01

Patients with active pulmonary sarcoidosis underwent bronchoalveolar lavage, gallium scan, and serum angiotensin-converting enzyme (ACE) level determination prior to treatment with corticosteroids. Pulmonary function was tested before and after therapy. Increase in vital capacity after treatment ranged from 40 to 1,030 ml; 12 of the 16 patients studied had an increase of more than 200 ml. There was a close correlation between the percentage uptake of gallium scan and the increase of the vital capacity after therapy (r . 0.95, p less than 0.01). There was no relationship between the percentage of lymphocytes obtained on lavage and the changes in vital capacity with therapy (r . 0.05). There was a positive correlation between the changes in vital capacity and the ratio of T4(+):T8(+)lymphocytes (r . 0.62, p less than 0.05) and number of T4 (+) lymphocytes (r . 0.92, p less than 0.01) in the bronchoalveolar fluid. There was a low correlation between the pretreatment ACE level and the change in vital capacity (r . 0.368, p greater than 0.05)

Micelle-stabilized room-temperature phosphorescence with synchronous scanning

International Nuclear Information System (INIS)

Femia, R.A.; Love, L.J.C.

1984-01-01

The experimental requirements for synchronous wavelength scanning micelle-stabilized room temperature phosphorescence and the factors affecting peak resolution are presented and compared with those for synchronous wavelength scanning fluorescence. Identification of individual compounds in a four-component mixture is illustrated, and criteria to identify and minimize triplet state energy transfer are given. Considerable improvement in resolution of the synchronous peaks is obtained via second derivative spectra. 20 references, 7 figures, 2 tables

Clinical significant of three phase radionuclide bone scan

Energy Technology Data Exchange (ETDEWEB)

Kim, Sun Hee; Suh, Jin Suck; Park, Chang Yun [Yonsei University College of Medicine, Seoul (Korea, Republic of)

1989-04-15

Three phase radionuclide bone scan, consisting of a radionuclide angiogram, an immediate postinjection blood pool image, and 4hr delayed images, was randomly performed in 182 patients, who had been suffered from either local pain or tenderness. Authors analysed 3 phase bone scan in 74 patients with correct diagnosis proven surgically or clinically, from July 1987 to August, 1988. The results were as follows: 1. Overall sensitivity of 3 phase bone scan was 85.4%: sensitivity in patients with an osseous lesion was 90.4% as opposed to 72.7% in patients with a nonosseous lesion. 2. There was no difference in the detection rate of the osseous lesions between the 3 phase bone scan and the delayed image bone scan. However, because the detection rate was higher on the 3 phase bone scan than it was on only the delayed image bone scan (55%) in instance of the nonosseous lesion, we would suggest that 3 phase bone scan might be obtained in cases suspected of the nonosseous lesions. 3. When the presumptive diagnosis was a bone tumor, sensitivity and specificity for malignancy were 67%, 100% respectively. 4. In differentiating osteomyelitis from cellulitis, sensitivity was 94%, specificity was 100%. 5. 3 phase bone scan was able to provide the precise information about either vasculaturity or localization of lesion in some cases of soft tissue mass and avascular necrosis of hips.

Scanning probe lithography for nanoimprinting mould fabrication

International Nuclear Information System (INIS)

Luo Gang; Xie Guoyong; Zhang Yongyi; Zhang Guoming; Zhang Yingying; Carlberg, Patrick; Zhu Tao; Liu Zhongfan

2006-01-01

We propose a rational fabrication method for nanoimprinting moulds by scanning probe lithography. By wet chemical etching, different kinds of moulds are realized on Si(110) and Si(100) surfaces according to the Si crystalline orientation. The structures have line widths of about 200 nm with a high aspect ratio. By reactive ion etching, moulds with patterns free from the limitation of Si crystalline orientation are also obtained. With closed-loop scan control of a scanning probe microscope, the length of patterned lines is more than 100 μm by integrating several steps of patterning. The fabrication process is optimized in order to produce a mould pattern with a line width about 10 nm. The structures on the mould are further duplicated into PMMA resists through the nanoimprinting process. The method of combining scanning probe lithography with wet chemical etching or reactive ion etching (RIE) provides a resistless route for the fabrication of nanoimprinting moulds

A history of a prior myocardial infarct does not negate the utility of myocardial perfusion imaging in the evaluation of acute chest pain syndromes

International Nuclear Information System (INIS)

Zhou Danbing; Jonathan Knott; Leeanne Grigg; Meir Lichtenstein; Nathan Better

2004-01-01

Purpose: Acute myocardial perfusion imaging (MPI) for evaluation of patients with acute chest pain and a non-diagnostic electrocardiogram (ECG) has a high sensitivity and moderate specificity to detect acute ischaemia and predict cardiac events. However, previous studies excluded patients with a history of prior myocardial infarction (MI). The purpose of our study was to assess the utility of acute MPI for evaluating patients with acute chest pain and a non-diagnostic ECG. We aim to study patients both with and without a history of prior MI, including normal and abnormal studies, as well as to assess the independent predictive value of a prior MI history in determining patient outcome. Methods: We studied 367 consecutive patients with (group 1, n--107) and without. (group 2, n=260) a history of prior MI. 800 MBq Tc99m sestamibi was injected while chest pain was present ('HOT' MIBI). SPECT imaging was performed 1-6 hours post injection. Scan results were reported as,normal, ischaemia, infarct or equivocal. For patients with a defect, a 24-hour painfree study ( C OLD' MIBI) was offered to differentiate ischaemia from infarct. Follow-up was at 1 year by review of the patient's medical record. Outcomes were (1) Hard cardiac events (HE), defined as cardiac death and non-fatal MI, and (2) Total cardiac events (TE), defined as HE or revascularisation. Results: For the total study population, 206 had a normal study, with a HE rate 0.97% (2/206), while 161 had an abnormal study, with HE rate 12.4% (20/161). Patients in Group 2 were much more likely to have a normal study than those in Group 1 (p<.001). An equivocal result is seen in 5 patients, with no cardiac events, while 5 patients had a non-cardiac death. These groups were too small for separate analysis. A COLD MIBI was required in 77.6% of group 1, but only 24.2% of group 2 patients (p<0.001). On univariate analysis, acute ischaemia on MIBI scan, history of prior MI, diabetes, Q wave on ECG and age are all predictors

Finding A Minimally Informative Dirichlet Prior Using Least Squares

International Nuclear Information System (INIS)

Kelly, Dana

2011-01-01

In a Bayesian framework, the Dirichlet distribution is the conjugate distribution to the multinomial likelihood function, and so the analyst is required to develop a Dirichlet prior that incorporates available information. However, as it is a multiparameter distribution, choosing the Dirichlet parameters is less straightforward than choosing a prior distribution for a single parameter, such as p in the binomial distribution. In particular, one may wish to incorporate limited information into the prior, resulting in a minimally informative prior distribution that is responsive to updates with sparse data. In the case of binomial p or Poisson λ, the principle of maximum entropy can be employed to obtain a so-called constrained noninformative prior. However, even in the case of p, such a distribution cannot be written down in the form of a standard distribution (e.g., beta, gamma), and so a beta distribution is used as an approximation in the case of p. In the case of the multinomial model with parametric constraints, the approach of maximum entropy does not appear tractable. This paper presents an alternative approach, based on constrained minimization of a least-squares objective function, which leads to a minimally informative Dirichlet prior distribution. The alpha-factor model for common-cause failure, which is widely used in the United States, is the motivation for this approach, and is used to illustrate the method. In this approach to modeling common-cause failure, the alpha-factors, which are the parameters in the underlying multinomial model for common-cause failure, must be estimated from data that are often quite sparse, because common-cause failures tend to be rare, especially failures of more than two or three components, and so a prior distribution that is responsive to updates with sparse data is needed.

Preoperative Duplex Scanning is a Helpful Diagnostic Tool in Neurogenic Thoracic Outlet Syndrome.

Science.gov (United States)

Orlando, Megan S; Likes, Kendall C; Mirza, Serene; Cao, Yue; Cohen, Anne; Lum, Ying Wei; Freischlag, Julie A

2016-01-01

To evaluate the diagnostic role of venous and arterial duplex scanning in neurogenic thoracic outlet syndrome (NTOS). Retrospective review of patients who underwent duplex ultrasonography prior to first rib resection and scalenectomy (FRRS) for NTOS from 2005 to 2013. Abnormal scans included ipsilateral compression (IC) with abduction of the symptomatic extremity (>50% change in subclavian vessel flow), contralateral (asymptomatic side) compression (CC) or bilateral compression (BC). A total of 143 patients (76% female, average age 34, range 13-59) underwent bilateral preoperative duplex scanning. Ipsilateral compression was seen in 44 (31%), CC in 12 (8%), and BC in 14 (10%). Seventy-three (51%) patients demonstrated no compression. Patients with IC more often experienced intraoperative pneumothoraces (49% vs. 25%, P duplex ultrasonography can assist in NTOS diagnosis. Ipsilateral compression on abduction often correlates with Adson testing. © The Author(s) 2016.

Evaluation of cross-linked chitosan microparticles containing acyclovir obtained by spray-drying

International Nuclear Information System (INIS)

Stulzer, Hellen Karine; Tagliari, Monika Piazzon; Parize, Alexandre Luis; Silva, Marcos Antonio Segatto; Laranjeira, Mauro Cesar Marghetti

2009-01-01

The aim of this study was to obtain microparticles containing acyclovir (ACV) and chitosan cross-linked with tripolyphosphate using the spray-drying technique. The resultant system was evaluated through loading efficiency, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), in vitro release and stability studies. The results obtained indicated that the polymer/ACV ratio influenced the final properties of the microparticles, with higher ratios giving the best encapsulation efficiency, dissolution profiles and stability. The DSC and XRPD analyses indicated that the ACV was transformed into amorphous form during the spray-drying process

Median prior constrained TV algorithm for sparse view low-dose CT reconstruction.

Science.gov (United States)

Liu, Yi; Shangguan, Hong; Zhang, Quan; Zhu, Hongqing; Shu, Huazhong; Gui, Zhiguo

2015-05-01

It is known that lowering the X-ray tube current (mAs) or tube voltage (kVp) and simultaneously reducing the total number of X-ray views (sparse view) is an effective means to achieve low-dose in computed tomography (CT) scan. However, the associated image quality by the conventional filtered back-projection (FBP) usually degrades due to the excessive quantum noise. Although sparse-view CT reconstruction algorithm via total variation (TV), in the scanning protocol of reducing X-ray tube current, has been demonstrated to be able to result in significant radiation dose reduction while maintain image quality, noticeable patchy artifacts still exist in reconstructed images. In this study, to address the problem of patchy artifacts, we proposed a median prior constrained TV regularization to retain the image quality by introducing an auxiliary vector m in register with the object. Specifically, the approximate action of m is to draw, in each iteration, an object voxel toward its own local median, aiming to improve low-dose image quality with sparse-view projection measurements. Subsequently, an alternating optimization algorithm is adopted to optimize the associative objective function. We refer to the median prior constrained TV regularization as "TV_MP" for simplicity. Experimental results on digital phantoms and clinical phantom demonstrated that the proposed TV_MP with appropriate control parameters can not only ensure a higher signal to noise ratio (SNR) of the reconstructed image, but also its resolution compared with the original TV method. Copyright © 2015 Elsevier Ltd. All rights reserved.

A new ultrasensitive scanning calorimeter.

Science.gov (United States)

Plotnikov, V V; Brandts, J M; Lin, L N; Brandts, J F

1997-08-01

A new ultrasensitive differential scanning calorimeter is described, having a number of novel features arising from integration between hardware and software. It is capable of high performance in either a scanning or isothermal mode of operation. Upscanning is carried out adiabatically while downscanning is nonadiabatic. By using software-controlled signals sent continuously to appropriate hardware devices, it is possible to improve adiabaticity and constancy of scan rate through use of empirical prerun information stored in memory rather than by using feedback systems which respond in real time and generate thermal noise. Also, instrument response time is software-selectable, maximizing performance for both slow- and fast-transient systems. While these and other sophisticated functionalities have been introduced into the instrument to improve performance and data analysis, they are virtually invisible and add no additional complexities into operation of the instrument. Noise and baseline repeatability are an order of magnitude better than published raw data from other instruments so that high-quality results can be obtained on protein solutions, for example, using as little as 50 microg of protein in the sample cell.

Improving Bayesian credibility intervals for classifier error rates using maximum entropy empirical priors.

Science.gov (United States)

Gustafsson, Mats G; Wallman, Mikael; Wickenberg Bolin, Ulrika; Göransson, Hanna; Fryknäs, M; Andersson, Claes R; Isaksson, Anders

2010-06-01

Successful use of classifiers that learn to make decisions from a set of patient examples require robust methods for performance estimation. Recently many promising approaches for determination of an upper bound for the error rate of a single classifier have been reported but the Bayesian credibility interval (CI) obtained from a conventional holdout test still delivers one of the tightest bounds. The conventional Bayesian CI becomes unacceptably large in real world applications where the test set sizes are less than a few hundred. The source of this problem is that fact that the CI is determined exclusively by the result on the test examples. In other words, there is no information at all provided by the uniform prior density distribution employed which reflects complete lack of prior knowledge about the unknown error rate. Therefore, the aim of the study reported here was to study a maximum entropy (ME) based approach to improved prior knowledge and Bayesian CIs, demonstrating its relevance for biomedical research and clinical practice. It is demonstrated how a refined non-uniform prior density distribution can be obtained by means of the ME principle using empirical results from a few designs and tests using non-overlapping sets of examples. Experimental results show that ME based priors improve the CIs when employed to four quite different simulated and two real world data sets. An empirically derived ME prior seems promising for improving the Bayesian CI for the unknown error rate of a designed classifier. Copyright 2010 Elsevier B.V. All rights reserved.

Incidental apical disease at CT scanning

International Nuclear Information System (INIS)

McLoud, T.C.; Satoh, K.; Shepard, J.O.; Moore, E.H.; Kosiuk, J.P.

1990-01-01

Apical caps are commonly noted on standard radiographs. This paper determines how often abnormalities in the extreme apex of the lung could be identified on CT scans obtained for other reasons. A total of 158 consecutive CT scans were reviewed prospectively. Excluded were patients with obvious upper lobe pleural or parenchymal disease. Apical abnormalities were identified in 74 (46.8%) of the 158 cases. The prevalence increased with age (19% in the 8-39-year age group and 82% in patients older than 80 years). Opacities were unilateral in 44.5% and bilateral in 55.5%. The most common abnormality was linear opacities (95%)

Is the Near-Earth Current Sheet Prior to Reconnection Unstable to Tearing Mode?

International Nuclear Information System (INIS)

Xin-Hua, Wei; Jin-Bin, Cao; Guo-Cheng, Zhou; Hui-Shan, Fu

2010-01-01

The tearing mode instability plays a key role in the triggering process of reconnection. The triggering collisionless tearing mode instability has been theoretically and numerically analyzed by many researchers. However, due to the difficulty in obtaining the observational wave number, it is still unknown whether the tearing mode instability can be excited in an actual plasma sheet prior to reconnection onset. Using the data from four Cluster satellites prior to a magnetospheric reconnection event on 13 September 2002, we utilized the wave telescope technique to obtain the wave number which corresponds to the peak of power spectral density. The wavelength is about 18R E and is consistent with previous theoretic and numerical results. After substituting the wave vector and other necessary parameters of the observed current sheet into the triggering condition of tearing mode instability, we find that the near-Earth current sheet prior to reconnection is unstable to tearing mode. (geophysics, astronomy, and astrophysics)

Role of technetium-99m planar bone scanning in the evaluation of low back pain

International Nuclear Information System (INIS)

Valdez, D.C.; Johnson, R.G.

1994-01-01

The records of 1018 patients with low back pain in a tertiary spine referral practice were reviewed. One hundred thirty-nine out of 1018 (13.6%) underwent technetium-99m planar bone scannings as part of their investigation. Seventy-three out of 139 scans (52%) showed increased uptake in some area, but only 27 out of 139 (19.4%) showed increased uptake specifically in the low back. Scans consistently yielded no findings with reference to the back when the prescan diagnosis was spinal stenosis, lumbar pain syndrome, herniated nucleus pulposus, or postlaminectomy syndrome. Some scans gave positive findings in patients with a diagnosis of degenerative disc disease, pseudoarthrosis, spondylolisthesis, fracture, infection, metabolic disorder, or tumor. Positive scans were generally obtained early after presentation (within 3 months) and negative scans obtained later (after 6 months), suggesting that clinical suspicion is still the main indication for early scanning. Planar bone scanning was helpful in both diagnosis and therapeutic decision-making in many conditions. (orig.)

Diagnosis of pituitary adenoma by dynamic CT scanning

International Nuclear Information System (INIS)

Tanabe, Sumiyoshi; Uede, Teiji; Daibo, Masahiko; Niwa, Jun; Hashi, Kazuo

1988-01-01

The advantage of high resolution CT in the diagnosis of pituitary microadenomas has been established, but the diagnosis becomes more difficult when the pituitary microadenoma is less than 5 mm in diameter. We have studied the usefulness of dynamic CT scans particularly for diagnosis of small microadenomas. The dynamic CT scans were performed for 61 normal pituitary glands and 68 pituitary adenomas (36 microadenomas, 32 macroadenomas) with a GECT/T 9800 scanner. Coronal sections of 1.5 mm thickness were taken at the plane just in front of the pituitary stalk of the pituitary gland. Following a bolus intra-venous injection of 40 - 60 ml of contrast media using an automatic injector, ten consecutive CT scans of 2 seconds scan time were obtained, beginning 2 seconds from the start of intravenous injection. The first seven scans were taken with an interval of 2.3 seconds, and the last three scans with an interval of 10 seconds. Then, time-density curves were obtained at the ROI which were set on the anterior pituitary gland, the vascular bed of the pituitary gland, the pituitary stalk and the area of the pituitary adenoma respectively. In a normal pituitary gland, the density increases gradually and makes an S shaped curve, then attains the maximum density value (92.3 CT number) approximately 60 seconds after the administration of contrast media. The pituitary vascular bed is located in midline on the upper surface of the pituitary gland, and shows a symmetrical square, triangular or rhomboid shape. In case of pituitary adenoma, the time-density curve makes a plateau curve and attains the maximum density value (60.1 CT number) approximately 60 seconds after the administration of contrast media. In microadenoma, the pituitary vascular bed is either deformed or compressed, showing an asymmetrical shape. (author)

Design of Test Wrapper Scan Chain Based on Differential Evolution

Directory of Open Access Journals (Sweden)

Aijun Zhu

2013-08-01

Full Text Available Integrated Circuit has entered the era of design of the IP-based SoC (System on Chip, which makes the IP core reuse become a key issue. SoC test wrapper design for scan chain is a NP Hard problem, we propose an algorithm based on Differential Evolution (DE to design wrapper scan chain. Through group’s mutation, crossover and selection operations, the design of test wrapper scan chain is achieved. Experimental verification is carried out according to the international standard benchmark ITC’02. The results show that the algorithm can obtain shorter longest wrapper scan chains, compared with other algorithms.

Molecular excited states from the SCAN functional

Science.gov (United States)

Tozer, David J.; Peach, Michael J. G.

2018-06-01

The performance of the strongly constrained and appropriately normed (SCAN) meta-generalised gradient approximation exchange-correlation functional is investigated for the calculation of time-dependent density-functional theory molecular excitation energies of local, charge-transfer and Rydberg character, together with the excited ? potential energy curve in H2. The SCAN results frequently resemble those obtained using a global hybrid functional, with either a standard or increased fraction of exact orbital exchange. For local excitations, SCAN can exhibit significant triplet instability problems, resulting in imaginary triplet excitation energies for a number of cases. The Tamm-Dancoff approximation offers a simple approach to improve the situation, but the excitation energies are still significantly underestimated. Understanding the origin of these (near)-triplet instabilities may provide useful insight into future functional development.

Aligned ion implantation using scanning probes

International Nuclear Information System (INIS)

Persaud, A.

2006-01-01

A new technique for precision ion implantation has been developed. A scanning probe has been equipped with a small aperture and incorporated into an ion beamline, so that ions can be implanted through the aperture into a sample. By using a scanning probe the target can be imaged in a non-destructive way prior to implantation and the probe together with the aperture can be placed at the desired location with nanometer precision. In this work first results of a scanning probe integrated into an ion beamline are presented. A placement resolution of about 120 nm is reported. The final placement accuracy is determined by the size of the aperture hole and by the straggle of the implanted ion inside the target material. The limits of this technology are expected to be set by the latter, which is of the order of 10 nm for low energy ions. This research has been carried out in the context of a larger program concerned with the development of quantum computer test structures. For that the placement accuracy needs to be increased and a detector for single ion detection has to be integrated into the setup. Both issues are discussed in this thesis. To achieve single ion detection highly charged ions are used for the implantation, as in addition to their kinetic energy they also deposit their potential energy in the target material, therefore making detection easier. A special ion source for producing these highly charged ions was used and their creation and interactions with solids of are discussed in detail. (orig.)

Aligned ion implementation using scanning probes

Energy Technology Data Exchange (ETDEWEB)

Persaud, A

2006-12-12

A new technique for precision ion implantation has been developed. A scanning probe has been equipped with a small aperture and incorporated into an ion beamline, so that ions can be implanted through the aperture into a sample. By using a scanning probe the target can be imaged in a non-destructive way prior to implantation and the probe together with the aperture can be placed at the desired location with nanometer precision. In this work first results of a scanning probe integrated into an ion beamline are presented. A placement resolution of about 120 nm is reported. The final placement accuracy is determined by the size of the aperture hole and by the straggle of the implanted ion inside the target material. The limits of this technology are expected to be set by the latter, which is of the order of 10 nm for low energy ions. This research has been carried out in the context of a larger program concerned with the development of quantum computer test structures. For that the placement accuracy needs to be increased and a detector for single ion detection has to be integrated into the setup. Both issues are discussed in this thesis. To achieve single ion detection highly charged ions are used for the implantation, as in addition to their kinetic energy they also deposit their potential energy in the target material, therefore making detection easier. A special ion source for producing these highly charged ions was used and their creation and interactions with solids of are discussed in detail. (orig.)

Permanent magnet finger-size scanning electron microscope columns

Energy Technology Data Exchange (ETDEWEB)

Nelliyan, K., E-mail: elenk@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)

2011-07-21

This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.

Permanent magnet finger-size scanning electron microscope columns

International Nuclear Information System (INIS)

Nelliyan, K.; Khursheed, A.

2011-01-01

This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.

An interchangeable scanning Hall probe/scanning SQUID microscope

International Nuclear Information System (INIS)

Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M. J.; Ling, D. C.; Chi, C. C.; Chen, Jeng-Chung

2014-01-01

We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10 −7 T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La 2/3 Ca 1/3 MnO 3 thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K

Application of Bayesian Decision Theory Based on Prior Information in the Multi-Objective Optimization Problem

Directory of Open Access Journals (Sweden)

Xia Lei

2010-12-01

Full Text Available General multi-objective optimization methods are hard to obtain prior information, how to utilize prior information has been a challenge. This paper analyzes the characteristics of Bayesian decision-making based on maximum entropy principle and prior information, especially in case that how to effectively improve decision-making reliability in deficiency of reference samples. The paper exhibits effectiveness of the proposed method using the real application of multi-frequency offset estimation in distributed multiple-input multiple-output system. The simulation results demonstrate Bayesian decision-making based on prior information has better global searching capability when sampling data is deficient.

Priming in implicit memory tasks: prior study causes enhanced discriminability, not only bias.

Science.gov (United States)

Zeelenberg, René; Wagenmakers, Eric-Jan M; Raaijmakers, Jeroen G W

2002-03-01

R. Ratcliff and G. McKoon (1995, 1996, 1997; R. Ratcliff, D. Allbritton, & G. McKoon, 1997) have argued that repetition priming effects are solely due to bias. They showed that prior study of the target resulted in a benefit in a later implicit memory task. However, prior study of a stimulus similar to the target resulted in a cost. The present study, using a 2-alternative forced-choice procedure, investigated the effect of prior study in an unbiased condition: Both alternatives were studied prior to their presentation in an implicit memory task. Contrary to a pure bias interpretation of priming, consistent evidence was obtained in 3 implicit memory tasks (word fragment completion, auditory word identification, and picture identification) that performance was better when both alternatives were studied than when neither alternative was studied. These results show that prior study results in enhanced discriminability, not only bias.

Identification of damage in plates using full-field measurement with a continuously scanning laser Doppler vibrometer system

Science.gov (United States)

Chen, Da-Ming; Xu, Y. F.; Zhu, W. D.

2018-05-01

An effective and reliable damage identification method for plates with a continuously scanning laser Doppler vibrometer (CSLDV) system is proposed. A new constant-speed scan algorithm is proposed to create a two-dimensional (2D) scan trajectory and automatically scan a whole plate surface. Full-field measurement of the plate can be achieved by applying the algorithm to the CSLDV system. Based on the new scan algorithm, the demodulation method is extended from one dimension for beams to two dimensions for plates to obtain a full-field operating deflection shape (ODS) of the plate from velocity response measured by the CSLDV system. The full-field ODS of an associated undamaged plate is obtained by using polynomials with proper orders to fit the corresponding full-field ODS from the demodulation method. A curvature damage index (CDI) using differences between curvatures of ODSs (CODSs) associated with ODSs that are obtained by the demodulation method and the polynomial fit is proposed to identify damage. An auxiliary CDI obtained by averaging CDIs at different excitation frequencies is defined to further assist damage identification. An experiment of an aluminum plate with damage in the form of 10.5% thickness reduction in a damage area of 0.86% of the whole scan area is conducted to investigate the proposed method. Six frequencies close to natural frequencies of the plate and one randomly selected frequency are used as sinusoidal excitation frequencies. Two 2D scan trajectories, i.e., a horizontally moving 2D scan trajectory and a vertically moving 2D scan trajectory, are used to obtain ODSs, CODSs, and CDIs of the plate. The damage is successfully identified near areas with consistently high values of CDIs at different excitation frequencies along the two 2D scan trajectories; the damage area is also identified by auxiliary CDIs.

Reappraisal of radionuclide liver scans for preoperative gastric cancer patients

Energy Technology Data Exchange (ETDEWEB)

Kondo, Makoto; Yonahara, Yoshio; Yamashita, Shoji; Ando, Yutaka; Mohri, Makoto [National Second Hospital of Tokyo (Japan)

1983-04-01

Radionuclide liver scans were obtained in 89 preoperative patients with gastric cancer. Eight showed definite defects on liver scans. At laparotomy, 14 patients were found to have liver involvement secondary to gastric cancer. The sensitivity of liver scans to predict liver involvement is 57% (8/14), and the specificity is 100% (75/75). The patients with definite defects on liver scans had a lower rate of palliative resection of the primary tumors (2/8) than the patients with liver involvement and no scan abnormality (4/6). The patients with advanced lesions but without liver involvement had the highest probability of resecting the primary tumors (57/63 : 47 radical, and 10 palliative). Normal serum levels of liver chemistries did not preclude the presence of defects on liver scans. Additional three patients were found to have cirrhosis of the liver solely based on liver scans, which was confirmed at laparotomy. Radionuclide liver scans can predict liver involvement with very few false positives, and may discriminate patients unsuitable for laparotomy even with palliative intent.

Case of asymmetrical arthrogryposis. A clinical study and a preliminary report on the value of CT-scanning

Energy Technology Data Exchange (ETDEWEB)

Hageman, G.; Vette, J.K.; Willemse, J. (University Hospital, Utrecht (Netherlands))

1983-01-01

Following the introduction of the conception that arthrogryposis is a symptom and not a clinical entity, a case of the very rare asymmetric form of neurogenic arthrogryposis is presented. The asymmetry of congenital contractures and weakness is associated with hemihypotrophy. The value of muscular CT-scanning prior to muscle biopsy is demonstrated. Muscular CT-scanning shows the extension of adipose tissue, which has replaced damaged muscles and therby indicates the exact site for muscle biopsy. Since orthopaedic treatment in arthrogryposis can be unrewarding due to severe muscular degeneration, preoperative scanning may provide additional important information on muscular function and thus be of benefit for surgery. The advantage of muscular CT-scanning in other forms of arthrogryposis requires further determination. The differential diagnosis with Werdnig-Hoffmann disease is discussed.

CT of multiple sclerosis: reassessment of delayed scanning with high doses of contrast material

International Nuclear Information System (INIS)

Spiegel, S.M.; Vinuela, F.; Fox, A.J.; Pelz, D.M.

1985-01-01

A prospective study involving 87 patients was carried out to evaluate the necessity for a high dose of contrast material in addition to delayed computed tomographic (CT) scanning for optimal detection of the lesions of multiple sclerosis in the brain. In patients with either clinically definite multiple sclerosis or laboratory-supported definite multiple sclerosis, CT scans were obtained with a uniform protocol. Lesions consistent with multiple sclerosis were demonstrated on the second scan in 54 patients. In 36 of these 54 patients, the high-dose delayed scan added information. These results are quite similar to those of a previous study from this institution using different patients, in whom the second scan was obtained immediately after the bolus injection of contrast material containing 40 g of organically bound iodine. The lack of real difference in the results of the two studies indicate that the increased dose, not just the delay in scanning, is necessary for a proper study

Observation of Magnetic Induction Distribution by Scanning Interference Electron Microscopy

Science.gov (United States)

Takahashi, Yoshio; Yajima, Yusuke; Ichikawa, Masakazu; Kuroda, Katsuhiro

1994-09-01

A scanning interference electron microscope (SIEM) capable of observing magnetic induction distribution with high sensitivity and spatial resolution has been developed. The SIEM uses a pair of fine coherent scanning probes and detects their relative phase change by magnetic induction, giving raster images of microscopic magnetic distributions. Its performance has been demonstrated by observing magnetic induction distributed near the edge of a recorded magnetic storage medium. Obtained images are compared with corresponding images taken in the scanning Lorentz electron microscope mode using the same microscope, and the differences between them are discussed.

An interchangeable scanning Hall probe/scanning SQUID microscope

Energy Technology Data Exchange (ETDEWEB)

Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Chen, Tse-Jun; Wang, M. J. [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan (China); Ling, D. C. [Department of Physics, Tamkang University, Tamsui Dist., New Taipei City 25137, Taiwan (China); Chi, C. C.; Chen, Jeng-Chung [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

2014-08-15

We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10{sup −7} T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La{sub 2/3}Ca{sub 1/3}MnO{sub 3} thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K.

An inverse method for determining the interaction force between the probe and sample using scanning near-field optical microscopy

International Nuclear Information System (INIS)

Chang, Win-Jin; Fang, Te-Hua

2006-01-01

This study proposes a means for calculating the interaction force during the scanning process using a scanning near-field optical microscope (SNOM) probe. The determination of the interaction force in the scanning system is regarded as an inverse vibration problem. The conjugate gradient method is applied to treat the inverse problem using available displacement measurements. The results show that the conjugate gradient method is less sensitive to measurement errors and prior information on the functional form of quality was not required. Furthermore, the initial guesses for the interaction force can be arbitrarily chosen for the iteration process

Assessment of myocardial perfusion using a new scanning agent

Energy Technology Data Exchange (ETDEWEB)

Khalil, M.N

1987-01-01

This work assessed a new compound: Tc-99m tertiary butyl isonitrile (T-BIN) in scanning the normal myocardium in dogs. Experimentally induced myocardial infarcts (M.I.) were detected. The compound cleared significantly from the blood within 15 minutes and from the lungs within an hour after intravenous administration. Liver uptake was high and remained so. Cardiac uptake occurred quickly and continued for 6 hours. Comparable results were obtained in normal humans and patients. Myocardial scanning was best after 60 minutes at rest or 30 minutes after exercise. Liver uptake sometimes obscured the detection of inferior M.I. but this problem was reduced using a 45/sup 0/ left anterior oblique view with a 20/sup 0/ cranial tilt. At rest 9/10 patients with M.I. showed defects corresponding to the infarct sites. In 20 patients with angina pectoris 16 had perfusion defects on exercise. In 15/16 patients reversible ischaemia was demonstrated. The reperfusion scans were best obtained at 4 hours post exercise. Both Tl-201 and T-BIN detected equally the infarcts (3/3) but in patients with angina 8/10 with T-BIN and 6/10 with Tl-201 showed defects. ECG gating of the T-BIN scans was also studied.

Detection of attack-targeted scans from the Apache HTTP Server access logs

Directory of Open Access Journals (Sweden)

Merve Baş Seyyar

2018-01-01

Full Text Available A web application could be visited for different purposes. It is possible for a web site to be visited by a regular user as a normal (natural visit, to be viewed by crawlers, bots, spiders, etc. for indexing purposes, lastly to be exploratory scanned by malicious users prior to an attack. An attack targeted web scan can be viewed as a phase of a potential attack and can lead to more attack detection as compared to traditional detection methods. In this work, we propose a method to detect attack-oriented scans and to distinguish them from other types of visits. In this context, we use access log files of Apache (or ISS web servers and try to determine attack situations through examination of the past data. In addition to web scan detections, we insert a rule set to detect SQL Injection and XSS attacks. Our approach has been applied on sample data sets and results have been analyzed in terms of performance measures to compare our method and other commonly used detection techniques. Furthermore, various tests have been made on log samples from real systems. Lastly, several suggestions about further development have been also discussed.

Soft control of scanning probe microscope with high flexibility.

Science.gov (United States)

Liu, Zhenghui; Guo, Yuzheng; Zhang, Zhaohui; Zhu, Xing

2007-01-01

Most commercial scanning probe microscopes have multiple embedded digital microprocessors and utilize complex software for system control, which is not easily obtained or modified by researchers wishing to perform novel and special applications. In this paper, we present a simple and flexible control solution that just depends on software running on a single-processor personal computer with real-time Linux operating system to carry out all the control tasks including negative feedback, tip moving, data processing and user interface. In this way, we fully exploit the potential of a personal computer in calculating and programming, enabling us to manipulate the scanning probe as required without any special digital control circuits and related technical know-how. This solution has been successfully applied to a homemade ultrahigh vacuum scanning tunneling microscope and a multiprobe scanning tunneling microscope.

A False Positive {sup 18}F-FDG PET/CT Scan Caused by Breast Silicone Injection

Energy Technology Data Exchange (ETDEWEB)

Chen, Chao Jung; Lee, Bi Fang; Yao, Wei Jen; Wu, Pei Shan; Chen, Wen Chung; Peng, Shu Lin; Chiu, Nan Tsing [Cheng Kung University Medical College and Hospital, Tainan (Turkmenistan)

2009-04-15

We present here the case of a 40-year-old woman with a greater than 10 year prior history of bilateral breast silicone injection and saline bag implantation. Bilateral palpable breast nodules were observed, but the ultrasound scan was suboptimal and the magnetic resonance imaging showed no gadolinium enhanced tumor. The {sup 18}F-FDG PET/CT scan showed a hypermetabolic nodule in the left breast with a 30% increase of {sup 18}F-FDG uptake on the delayed imaging, and this mimicked breast cancer. She underwent a left partial mastectomy and the pathology demonstrated a siliconoma.

Evaluation of /sup 111/In leukocyte whole body scanning

Energy Technology Data Exchange (ETDEWEB)

McDougall, I.R.; Baumert, J.E.; Lantieri, R.L.

1979-11-01

Indium-111 oxine, polymorphonuclear cells isolated and labeled with /sup 111/In were used for studying abscesses and inflammatory conditions. There were 64 total scans done in 59 patients, 32 male and 27 female, aged 3 to 81 years (average, 51). The original clinical diagnosis was abscess in 33 patients. The whole blood cell scan was abnormal in 12 (36%) of these, and a good clinical correlation was obtained in 11 of the 12. In the 21 with a normal scan, 18 had no evidence of abscess, yielding one false-positive and three false-negative interpretations in the abscess group. Thirteen patients had fever of unknown origin, nine had negative scans and no subsequent evidence of abscess, and four had positive scans with good correlation in three. Acute bone and joint infections were positive on scan (4/4), whereas chronic osteomyelitis was negative (0/2). Three patients with acute myocardial infarction and three of four with subacute bacterial endocarditis had normal scans. All three studies in renal transplant rejection showed positive uptake in the pelvic kidneys. Indium-111 white blood cell scans have proved useful to diagnose or exclude a diagnosis of abscess or inflammatory condition infiltrated with polymorphonuclear leukocytes.

Fluence scan: an unexplored property of a laser beam

International Nuclear Information System (INIS)

Chalupsky, Jaromir; Hajkova, Vera; Burian, Tomas; Juha, Libor; Polcar, Tomas; Gaudin, Jerome; Nagasono, Mitsuru; Yabashi, Makina; Sobierajski, Ryszard; Krzywinski, Jacek

2013-01-01

We present an extended theoretical background of so-called fluence scan (f-scan or F-scan) method, which is frequently being used for offline characterization of focused short-wavelength (EUV, soft X-ray, and hard X-ray) laser beams [J. Chalupsky et al., Opt. Express 18, 27836 (2010)]. The method exploits ablative imprints in various solids to visualize iso-fluence beam contours at different fluence and/or clip levels. An f-scan curve (clip level as a function of the corresponding iso-fluence contour area) can be generated for a general non-Gaussian beam. As shown in this paper, fluence scan encompasses important information about energy distribution within the beam profile, which may play an essential role in laser-matter interaction research employing intense non-ideal beams. Here we for the first time discuss fundamental properties of the f-scan function and its inverse counterpart (if-scan). Furthermore, we extensively elucidate how it is related to the effective beam area, energy distribution, and to the so called Liu's dependence [J.M. Liu, Opt. Lett. 7, 196 (1982)]. A new method of the effective area evaluation based on weighted inverse f-scan fit is introduced and applied to real data obtained at the SCSS (SPring-8 Compact SASE Source) facility. (authors)

A first order approximation of the tumor absorbed dose prior to treatment with Sr-89

Energy Technology Data Exchange (ETDEWEB)

Manetou, A [NIMITS Hospital, Medical Physics Unit, Athens (Greece); Toubanakis, N; Lyra, M; Lymouris, G [Areteion University Hospital, Radiology Department, Athens (Greece)

1994-12-31

A new technique developed for the estimation of the absorbed dose prior to treatment with Sr-89 is presented. This technique implies that patient undergoes bone scanning with Tc-99m-MDP, two days before the administration of Sr-89. A number of sequential quantitative images are to be obtained over the first 8 hours after the Tc-99m-MDP injection and data are used to derive St-89 time retention curve. For the development of this technique a simplified model for the kinetics of both Sr-89 and Tc-99m-MDP was assumed. Data on the time retention of the two radiopharmaceuticals for a compartment including bone surface and bone space of trabecular and cortical bone for normal adults were combined together. A linear relationship was derived between the time required for the same percentage uptake of the two radiopharmaceuticals after single injection. The absorbed dose in the principal metastases and normal bone, of the same type and volume with the metastases, for two patients who were treated with Sr-89 for metastasized prostatic carcinoma are reported. (authors). 23 refs,3 figs, 2 tabs.

Carbon nanofibers obtained from electrospinning process

Science.gov (United States)

Bovi de Oliveira, Juliana; Müller Guerrini, Lília; Sizuka Oishi, Silvia; Rogerio de Oliveira Hein, Luis; dos Santos Conejo, Luíza; Cerqueira Rezende, Mirabel; Cocchieri Botelho, Edson

2018-02-01

In recent years, reinforcements consisting of carbon nanostructures, such as carbon nanotubes, fullerenes, graphenes, and carbon nanofibers have received significant attention due mainly to their chemical inertness and good mechanical, electrical and thermal properties. Since carbon nanofibers comprise a continuous reinforcing with high specific surface area, associated with the fact that they can be obtained at a low cost and in a large amount, they have shown to be advantageous compared to traditional carbon nanotubes. The main objective of this work is the processing of carbon nanofibers, using polyacrylonitrile (PAN) as a precursor, obtained by the electrospinning process via polymer solution, with subsequent use for airspace applications as reinforcement in polymer composites. In this work, firstly PAN nanofibers were produced by electrospinning with diameters in the range of (375 ± 85) nm, using a dimethylformamide solution. Using a furnace, the PAN nanofiber was converted into carbon nanofiber. Morphologies and structures of PAN and carbon nanofibers were investigated by scanning electron microscopy, Raman Spectroscopy, thermogravimetric analyses and differential scanning calorimeter. The resulting residual weight after carbonization was approximately 38% in weight, with a diameters reduction of 50%, and the same showed a carbon yield of 25%. From the analysis of the crystalline structure of the carbonized material, it was found that the material presented a disordered structure.

NEW SCANNING DEVICE FOR SCANNING TUNNELING MICROSCOPE APPLICATIONS

NARCIS (Netherlands)

SAWATZKY, GA; Koops, Karl Richard

A small, single piezo XYZ translator has been developed. The device has been used as a scanner for a scanning tunneling microscope and has been tested successfully in air and in UHV. Its simple design results in a rigid and compact scanning unit which permits high scanning rates.

Nuclear Scans

Science.gov (United States)

Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

Laparoscopic Meckel's diverticulumectomy following positive Meckel's diverticulum scan

International Nuclear Information System (INIS)

Mansberg, R.; Roberts, J.M.; Tan, B.

2002-01-01

Full text: Laparoscopic or 'keyhole' surgery is increasingly performed to reduce morbidity and length of hospital admissions. Laparoscopic resection of a Meckel's Diverticulum has rarely been performed as the diagnosis is only rarely made prior to surgery and most patients proceed to exploratory laparotomy. A positive Meckel's scan and subsequent laparoscopic Meckel's Diverticulumectomy is presented. A 26-year-old male tourist presented with GIT bleeding following acute alcohol ingestion. He had previously been unsuccessfully investigated in England for GIT bleeding. Following a negative gastroscopy a Meckel's Diverticulum scan was performed. The study clearly demonstrated ectopic gastrin secreting mucosa in the right iliac fossa .The following day the patient went to theatre and at laparoscopy the Meckel's diverticulum was identified and resected. Histological examination confirmed the diagnosis of a Meckel's Diverticulum. The patient returned to England 2 days later. This case illustrates how a scintigraphic diagnosis can avoid exploratory surgery and result in less invasive laparoscopic surgery. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

CT scanning of the breast in problem cases

Energy Technology Data Exchange (ETDEWEB)

John, V.; Ewen, K. (Essen Univ. (Gesamthochschule) (Germany, F.R.). Radiologisches Zentrum; Zentralstelle fuer Sicherheitstechnik, Duesseldorf (Germany, F.R.))

1989-09-01

This is a report of the experience with 200 patients who during 1981 to 1984 underwent breast scanning on a conventional body scanner. Pre- and post-contrast scans of the breast were obtained. A postcontrast enhancement of 50 HU and more turned out to be specific for malignant lesions. Radiation dose to the breast was in the same range as with high filtration xeromammography and high resolution film-screen mammography with additional grid. Breast scanning is recommended in cases in which mammography alone is of limited value, including dense fibrocystic breasts in women at high risk, follow-up in breast cancer patients after breast conserving therapy, in patients with silastic implants and in the follow-up of breasts with huge scars due to multiple biopsies. (orig.).

l0 regularization based on a prior image incorporated non-local means for limited-angle X-ray CT reconstruction.

Science.gov (United States)

Zhang, Lingli; Zeng, Li; Guo, Yumeng

2018-03-15

Restricted by the scanning environment in some CT imaging modalities, the acquired projection data are usually incomplete, which may lead to a limited-angle reconstruction problem. Thus, image quality usually suffers from the slope artifacts. The objective of this study is to first investigate the distorted domains of the reconstructed images which encounter the slope artifacts and then present a new iterative reconstruction method to address the limited-angle X-ray CT reconstruction problem. The presented framework of new method exploits the structural similarity between the prior image and the reconstructed image aiming to compensate the distorted edges. Specifically, the new method utilizes l0 regularization and wavelet tight framelets to suppress the slope artifacts and pursue the sparsity. New method includes following 4 steps to (1) address the data fidelity using SART; (2) compensate for the slope artifacts due to the missed projection data using the prior image and modified nonlocal means (PNLM); (3) utilize l0 regularization to suppress the slope artifacts and pursue the sparsity of wavelet coefficients of the transformed image by using iterative hard thresholding (l0W); and (4) apply an inverse wavelet transform to reconstruct image. In summary, this method is referred to as "l0W-PNLM". Numerical implementations showed that the presented l0W-PNLM was superior to suppress the slope artifacts while preserving the edges of some features as compared to the commercial and other popular investigative algorithms. When the image to be reconstructed is inconsistent with the prior image, the new method can avoid or minimize the distorted edges in the reconstructed images. Quantitative assessments also showed that applying the new method obtained the highest image quality comparing to the existing algorithms. This study demonstrated that the presented l0W-PNLM yielded higher image quality due to a number of unique characteristics, which include that (1) it utilizes

A Fourier Transform Spectrometer Based on an Electrothermal MEMS Mirror with Improved Linear Scan Range

Directory of Open Access Journals (Sweden)

Wei Wang

2016-09-01

Full Text Available A Fourier transform spectrometer (FTS that incorporates a closed-loop controlled, electrothermally actuated microelectromechanical systems (MEMS micromirror is proposed and experimentally verified. The scan range and the tilting angle of the mirror plate are the two critical parameters for MEMS-based FTS. In this work, the MEMS mirror with a footprint of 4.3 mm × 3.1 mm is based on a modified lateral-shift-free (LSF bimorph actuator design with large piston and reduced tilting. Combined with a position-sensitive device (PSD for tilt angle sensing, the feedback controlled MEMS mirror generates a 430 µm stable linear piston scan with the mirror plate tilting angle less than ±0.002°. The usable piston scan range is increased to 78% of the MEMS mirror’s full scan capability, and a spectral resolution of 0.55 nm at 531.9 nm wavelength, has been achieved. It is a significant improvement compared to the prior work.

Medical Radioisotope Scanning, Vol. II. Proceedings of the Symposium on Medical Radioisotope Scanning

International Nuclear Information System (INIS)

1964-01-01

Medical applications of radioisotopes continue to grow in number and importance and medical centres in almost all countries of the world are now using radioactive materials both in the diagnosis and treatment of disease. An increasing proportion of these applications involves studies of the spatial distribution of radioactive material within the human body, for which purpose highly specialized scanning methods have been elaborated. By these methods it is possible to study the position, size and functional state of different organs, to detect tumours, cysts and other abnormalities and to obtain much useful information about regions of the body that are otherwise inaccessible, except by surgery. Progress in scanning methods in recent years has been very rapid and there have been many important advances in instrumentation and technique. The development of new forms of the gamma camera and of colour-scanning techniques are but two examples of recent improvements. The production of new radioisotopes and new labelled compounds has further extended the scope of these methods. To survey these new advances the International Atomic Energy Agency held a Symposium on Medical Radioisotope Scanning in Athens from 20-24 April 1964. The scientific programme of the meeting covered all aspects of scanning methods including theoretical principles, instrumentation, techniques and clinical applications. The World Health Organization assisted in the selection of papers by providing a consultant to the selection committee. The meeting followed the earlier IAEA/WHO Seminar on Medical Radioisotope Scanning in Vienna in 1959, which was attended by 36 participants and at which 14 papers were presented. Some idea of the growth of interest in the subject may be gained from the fact that the Symposium was attended by 160 participants from 26 countries and 4 international organizations, and that 58 papers were presented. The published proceedings, comprising two volumes, contain all the

Colon distension and scan protocol for CT-colonography: An overview

Energy Technology Data Exchange (ETDEWEB)

Boellaard, Thierry N., E-mail: t.n.boellaard@amc.uva.nl [Department of Radiology, Academic Medical Center, University of Amsterdam, PB 22660, 1100 DD Amsterdam (Netherlands); Haan, Margriet C. de, E-mail: m.c.dehaan@amc.uva.nl [Department of Radiology, Academic Medical Center, University of Amsterdam, PB 22660, 1100 DD Amsterdam (Netherlands); Venema, Henk W., E-mail: h.w.venema@amc.uva.nl [Department of Radiology, Academic Medical Center, University of Amsterdam, PB 22660, 1100 DD Amsterdam (Netherlands); Department of Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, PB 22660, 1100 DD Amsterdam (Netherlands); Stoker, Jaap, E-mail: j.stoker@amc.uva.nl [Department of Radiology, Academic Medical Center, University of Amsterdam, PB 22660, 1100 DD Amsterdam (Netherlands)

2013-08-15

This article reviews two important aspects of CT-colonography, namely colonic distension and scan parameters. Adequate distension should be obtained to visualize the complete colonic lumen and optimal scan parameters should be used to prevent unnecessary radiation burden. For optimal distension, automatic carbon dioxide insufflation should be performed, preferably via a thin, flexible catheter. Hyoscine butylbromide is – when available – the preferred spasmolytic agent because of the positive effect on insufflation and pain/burden and its low costs. Scans in two positions are required for adequate distension and high polyp sensitivity and decubitus position may be used as an alternative for patients unable to lie in prone position. The great intrinsic contrast between air or tagging and polyps allows the use of low radiation dose. Low-dose protocol without intravenous contrast should be used when extracolonic findings are deemed unimportant. In patients suspected for colorectal cancer, normal abdominal CT scan protocols and intravenous contrast should be used in supine position for the evaluation of extracolonic findings. Dose reduction can be obtained by lowering the tube current and/or voltage. Tube current modulation reduces the radiation dose (except in obese patients), and should be used when available. Iterative reconstructions is a promising dose reducing tool and dual-energy CT is currently evaluated for its applications in CT-colonography. This review also provides our institution's insufflation procedure and scan parameters.

Effects of prior aversive experience upon retrograde amnesia induced by hypothermia.

Science.gov (United States)

Jensen, R A; Riccio, D C; Gehres, L

1975-08-01

Two experiments examined the extent to which retrograde amnesia (RA) is attenuated by prior learning experiences. In Experiment 1, rats initially received either passive avoidance training in a step-through apparatus, exposure to the apparatus, or noncontingent footshock. When training on a second but different passive avoidance task was followed by hypothermia treatment, RA was obtained only in the latter two groups. In Experiment 2, one-way active avoidance training, yoked noncontingent shocks, or apparatus exposure constituted the initial experience. Subsequent step-down passive avoidance training and amnestic treatment resulted in memory loss for the prior apparatus exposure group, but not for either of the preshocked conditions. These experiments demonstrate that certain types of prior aversive experience can substantially modify the magnitude of RA, and, in conjunction with other familiarization studies, emphasize a paradox for interpretations of RA based solely upon CNS disruption. The possibility that hypothermia treatment serves as an important contextual or encoding cue necessary for memory retrieval was considered. It was suggested that prior experience may block RA by enabling rats to differentiate training and treatment conditions.

Propofol drip infusion anesthesia for MRI scanning: two case reports.

Science.gov (United States)

Sasao-Takano, Mami; Misumi, Kan; Suzuki, Masayuki; Kamiya, Yoko; Noguchi, Izumi; Kawahara, Hiroshi

2013-01-01

The magnetic resonance imaging (MRI) room is a special environment. The required intense magnetic fields create unique problems with the use of standard anesthesia machines, syringe pumps, and physiologic monitors. We have recently experienced 2 oral maxillofacial surgery cases requiring MRI: a 15-year-old boy with developmental disability and a healthy 5-year-old boy. The patients required complete immobilization during the scanning for obtaining high-quality images for the best diagnosis. Anesthesia was started in the MRI scanning room. An endotracheal intubation was performed after induction with intravenous administration of muscle relaxant. Total intravenous anesthesia via propofol drip infusion (4-7 mg/kg/h) was used during the scanning. Standard physiologic monitors were used during scan pauses, but special monitors were used during scanning. In MRI scanning for oral maxillofacial surgery, general anesthesia, with the added advantage of having a secured airway, is recommended as a safe alternative to sedation especially in cases of patients with disability and precooperative chidren.

Translate rotate scanning method for X-ray imaging

International Nuclear Information System (INIS)

Eberhard, J.W.; Kwog Cheong Tam.

1990-01-01

Rapid x-ray inspection of objects larger than an x-ray detector array is based on a translate rotate scanning motion of the object related to the fan beam source and detector. The scan for computerized tomography imaging is accomplished by rotating the object through 360 degrees at two or more positions relative to the source and detector array, in moving to another position the object is rotated and the object or source and detector are translated. A partial set of x-ray data is acquired at every position which are combined to obtain a full data set for complete image reconstruction. X-ray data for digital radiography imaging is acquired by scanning the object vertically at a first position at one view angle, rotating and translating the object relative to the source and detector to a second position, scanning vertically, and so on to cover the object field of view, and combining the partial data sets. (author)

Indium-granulocyte scanning in the painful prosthetic joint

International Nuclear Information System (INIS)

Pring, D.J.; Henderson, R.G.; Keshavarzian, A.; Rivett, A.G.; Krausz, T.; Coombs, R.R.; Lavender, J.P.

1986-01-01

The value of indium-111-labeled granulocyte scanning to determine the presence of infection was assessed in 50 prosthetic joints (41 of which were painful) in 40 patients. Granulocytes were obtained from the patients' blood and labeled in plasma with indium 111 tropolonate. Abnormal accumulation of indium 111 in the region of the prosthesis was noted. Proven infection occurred in 11 prostheses, and all of the infections were detected by indium-111-labeled granulocyte scanning. Nineteen were not infected (including nine asymptomatic controls) and only two produced false-positive scans. This represents a specificity of 89.5%, sensitivity of 100%, and overall accuracy of 93.2%. These results compare favorably with plain radiography. There was no radiologic evidence of infection in three of the infected prostheses, and 10 of the noninfected prostheses had some radiologic features that suggested sepsis. We conclude that indium-granulocyte scanning can reliably detect or exclude infection in painful prosthetic joints and should prove useful in clinical management

Fast-scan NMR imaging

International Nuclear Information System (INIS)

Iwaoka, Hideto; Matsuura, Hiroyuki; Sugiyama, Tadashi; Hirata, Takaaki

1987-01-01

This paper describes the Fast Recovery (FR) method for fast-scan Nuclear Magnetic Resonance imaging. The FR method uses a sequence of four radio frequency pulses - alternating selective 90 deg nutation pulses and nonselective 180 deg pulses. One free induction decay (FID) signal and one echo signal are detected and averaged to compute a 2-D image. In the modified FR method, extra 180 deg pulses are applied between 90 deg pulses to cause refocusing and the resultant spin echo signals are averaged to improve the signal to noise ratio. For the FR and modified FR sequences, the macroscopic magnetization is restored to equilibrium quickly and exactly; scan time can consequently be less than that for conventional pulse sequences, such as used in the saturation recovery method, without any penalty in signal to noise ratio. This paper derives expressions for the signal to noise ratio, scan time ratio and contrast noise ratio, compares the FR and modified FR methods with the saturation recovery method and presents experimental results for human body images. In theory and practice, the signal to noise ratio for the FR method is larger than that for the modified FR method. For a given signal to noise ratio the scan time is between one half and one fourth that for the saturation recovery method. The optimum repetition period, T r , is 0.07 ∼ 0.25 s for the FR method, and 0.1 ∼ 0.5 s for the modified FR method. Contrast noise ratio is low for high speed imaging, T r = 0.07 ∼ 0.25 s, but, high contrast noise ratio image is obtained for T r > 0.5 s. (author)

Research on Radar Cross Section Measurement Based on Near-field Imaging of Cylindrical Scanning

Directory of Open Access Journals (Sweden)

Xing Shu-guang

2015-04-01

Full Text Available A new method of Radar Cross Section (RCS measurement based on near-field imaging of cylindrical scanning surface is proposed. The method is based on the core assumption that the target consists of ideal isotropic scattered centers. Three-dimensional radar scattered images are obtained by using the proposed method, and then to obtain the RCS of the target, the scattered far field is calculated by summing the fields generated by the equivalent scattered centers. Not only three dimensional radar reflectivity images but also the RCS of targets in certain three dimensional angle areas can be obtained. Compared with circular scanning that can only obtain twodimensional radar reflectivity images and RCS results in two-dimensional angle areas, cylindrical scanning can provide more information about the scattering properties of the targets. The method has strong practicability and its validity is verified by simulations.

A Simulation of Pell Grant Awards and Costs Using Prior-Prior Year Financial Data

Science.gov (United States)

Kelchen, Robert; Jones, Gigi

2015-01-01

We examine the likely implications of switching from a prior year (PY) financial aid system, the current practice in which students file the Free Application for Federal Student Aid (FAFSA) using income data from the previous tax year, to prior-prior year (PPY), in which data from two years before enrollment is used. While PPY allows students to…

Clinical discussion of adrenal scan by 131I-adosterol

International Nuclear Information System (INIS)

Kubo, Atsushi

1976-01-01

131 I-adosterol adrenal scan was conducted to 31 patients. Clear positive images were obtained at the adrenal gland at the side of cortical adenoma on scintigram in all of 5 patients with primary aldosteronism and 5 patients with Cushing's syndrome. It was found that the quantitative measurements of 131 I-adosterol % uptake and of right-to-left uptake ratio do not only make a regional diagnosis of adrenocortical tumor more positive, but also they make the state of adrenocortical function known to an extent. Adrenal scan is easy to be used, and is non-invasive to patients. The obtained results are diagnostically valuable. It is considered that 131 I-Adosterol is an excellent radiopharmaceutical having the sufficient efficacy for adrenal diseases. (Ichikawa, K.)

Comparison of dimensional accuracy of digital dental models produced from scanned impressions and scanned stone casts

Science.gov (United States)

Subeihi, Haitham

Introduction: Digital models of dental arches play a more and more important role in dentistry. A digital dental model can be generated by directly scanning intraoral structures, by scanning a conventional impression of oral structures or by scanning a stone cast poured from the conventional impression. An accurate digital scan model is a fundamental part for the fabrication of dental restorations. Aims: 1. To compare the dimensional accuracy of digital dental models produced by scanning of impressions versus scanning of stone casts. 2. To compare the dimensional accuracy of digital dental models produced by scanning of impressions made of three different materials (polyvinyl siloxane, polyether or vinyl polyether silicone). Methods and Materials: This laboratory study included taking addition silicone, polyether and vinyl polyether silicone impressions from an epoxy reference model that was created from an original typodont. Teeth number 28 and 30 on the typodont with a missing tooth number 29 were prepared for a metal-ceramic three-unit fixed dental prosthesis with tooth #29 being a pontic. After tooth preparation, an epoxy resin reference model was fabricated by duplicating the typodont quadrant that included the tooth preparations. From this reference model 12 polyvinyl siloxane impressions, 12 polyether impressions and 12 vinyl polyether silicone impressions were made. All 36 impressions were scanned before pouring them with dental stone. The 36 dental stone casts were, in turn, scanned to produce digital models. A reference digital model was made by scanning the reference model. Six groups of digital models were produced. Three groups were made by scanning of the impressions obtained with the three different materials, the other three groups involved the scanning of the dental casts that resulted from pouring the impressions made with the three different materials. Groups of digital models were compared using Root Mean Squares (RMS) in terms of their

Use of rapid-scan EPR to improve detection sensitivity for spin-trapped radicals.

Science.gov (United States)

Mitchell, Deborah G; Rosen, Gerald M; Tseitlin, Mark; Symmes, Breanna; Eaton, Sandra S; Eaton, Gareth R

2013-07-16

The short lifetime of superoxide and the low rates of formation expected in vivo make detection by standard continuous wave (CW) electron paramagnetic resonance (EPR) challenging. The new rapid-scan EPR method offers improved sensitivity for these types of samples. In rapid-scan EPR, the magnetic field is scanned through resonance in a time that is short relative to electron spin relaxation times, and data are processed to obtain the absorption spectrum. To validate the application of rapid-scan EPR to spin trapping, superoxide was generated by the reaction of xanthine oxidase and hypoxanthine with rates of 0.1-6.0 μM/min and trapped with 5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO). Spin trapping with BMPO to form the BMPO-OOH adduct converts the very short-lived superoxide radical into a more stable spin adduct. There is good agreement between the hyperfine splitting parameters obtained for BMPO-OOH by CW and rapid-scan EPR. For the same signal acquisition time, the signal/noise ratio is >40 times higher for rapid-scan than for CW EPR. Rapid-scan EPR can detect superoxide produced by Enterococcus faecalis at rates that are too low for detection by CW EPR. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Arterial tree tracking from anatomical landmarks in magnetic resonance angiography scans

Science.gov (United States)

O'Neil, Alison; Beveridge, Erin; Houston, Graeme; McCormick, Lynne; Poole, Ian

2014-03-01

This paper reports on arterial tree tracking in fourteen Contrast Enhanced MRA volumetric scans, given the positions of a predefined set of vascular landmarks, by using the A* algorithm to find the optimal path for each vessel based on voxel intensity and a learnt vascular probability atlas. The algorithm is intended for use in conjunction with an automatic landmark detection step, to enable fully automatic arterial tree tracking. The scan is filtered to give two further images using the top-hat transform with 4mm and 8mm cubic structuring elements. Vessels are then tracked independently on the scan in which the vessel of interest is best enhanced, as determined from knowledge of typical vessel diameter and surrounding structures. A vascular probability atlas modelling expected vessel location and orientation is constructed by non-rigidly registering the training scans to the test scan using a 3D thin plate spline to match landmark correspondences, and employing kernel density estimation with the ground truth center line points to form a probability density distribution. Threshold estimation by histogram analysis is used to segment background from vessel intensities. The A* algorithm is run using a linear cost function constructed from the threshold and the vascular atlas prior. Tracking results are presented for all major arteries excluding those in the upper limbs. An improvement was observed when tracking was informed by contextual information, with particular benefit for peripheral vessels.

Finding a minimally informative Dirichlet prior distribution using least squares

International Nuclear Information System (INIS)

Kelly, Dana; Atwood, Corwin

2011-01-01

In a Bayesian framework, the Dirichlet distribution is the conjugate distribution to the multinomial likelihood function, and so the analyst is required to develop a Dirichlet prior that incorporates available information. However, as it is a multiparameter distribution, choosing the Dirichlet parameters is less straightforward than choosing a prior distribution for a single parameter, such as p in the binomial distribution. In particular, one may wish to incorporate limited information into the prior, resulting in a minimally informative prior distribution that is responsive to updates with sparse data. In the case of binomial p or Poisson λ, the principle of maximum entropy can be employed to obtain a so-called constrained noninformative prior. However, even in the case of p, such a distribution cannot be written down in the form of a standard distribution (e.g., beta, gamma), and so a beta distribution is used as an approximation in the case of p. In the case of the multinomial model with parametric constraints, the approach of maximum entropy does not appear tractable. This paper presents an alternative approach, based on constrained minimization of a least-squares objective function, which leads to a minimally informative Dirichlet prior distribution. The alpha-factor model for common-cause failure, which is widely used in the United States, is the motivation for this approach, and is used to illustrate the method. In this approach to modeling common-cause failure, the alpha-factors, which are the parameters in the underlying multinomial model for common-cause failure, must be estimated from data that are often quite sparse, because common-cause failures tend to be rare, especially failures of more than two or three components, and so a prior distribution that is responsive to updates with sparse data is needed.

Finding a Minimally Informative Dirichlet Prior Distribution Using Least Squares

International Nuclear Information System (INIS)

Kelly, Dana; Atwood, Corwin

2011-01-01

In a Bayesian framework, the Dirichlet distribution is the conjugate distribution to the multinomial likelihood function, and so the analyst is required to develop a Dirichlet prior that incorporates available information. However, as it is a multiparameter distribution, choosing the Dirichlet parameters is less straight-forward than choosing a prior distribution for a single parameter, such as p in the binomial distribution. In particular, one may wish to incorporate limited information into the prior, resulting in a minimally informative prior distribution that is responsive to updates with sparse data. In the case of binomial p or Poisson, the principle of maximum entropy can be employed to obtain a so-called constrained noninformative prior. However, even in the case of p, such a distribution cannot be written down in closed form, and so an approximate beta distribution is used in the case of p. In the case of the multinomial model with parametric constraints, the approach of maximum entropy does not appear tractable. This paper presents an alternative approach, based on constrained minimization of a least-squares objective function, which leads to a minimally informative Dirichlet prior distribution. The alpha-factor model for common-cause failure, which is widely used in the United States, is the motivation for this approach, and is used to illustrate the method. In this approach to modeling common-cause failure, the alpha-factors, which are the parameters in the underlying multinomial aleatory model for common-cause failure, must be estimated from data that is often quite sparse, because common-cause failures tend to be rare, especially failures of more than two or three components, and so a prior distribution that is responsive to updates with sparse data is needed.

Brain PET scan

Science.gov (United States)

... results on a PET scan. Blood sugar or insulin levels may affect the test results in people with diabetes . PET scans may be done along with a CT scan. This combination scan is called a PET/CT. Alternative Names Brain positron emission tomography; PET scan - brain References Chernecky ...

Homogeneous dose distribution of electrons obtained from linear accelerators equipped with beam scanners

International Nuclear Information System (INIS)

Borchardt, D.; Cwiekala, M.; Schroeder, U.G.

1985-01-01

Homogeneous distribution of electrons used for therapeutic purposes and obtained from accelerators, is achieved by means of Potter-Bucky diaphragms or by repeated, staggered, sawtooth-shaped sweeping movements of the electron beam (scanning) over the radiation field. The repetition of the scanning process (number of scans) can result in long measurement times for achieving a sufficiently homogeneous, dosimetrically adequate distribution of the electrons. This ''time problem'' makes it imperative to achieve good homogeneity while keeping the number of scans as low as possible. To solve the problem, the scanning movement of the electron beam is simulated by a computer programme and the independence of the homogeneity of the irradiation field and number of scans is investigated. Since changing the ratio of the two deflection rates exercises a significant influence, it is mandatory in dosimetry to pay close attention to strict observance of the deflection rates. (orig.) [de

Compressed-sensing wavenumber-scanning interferometry

Science.gov (United States)

Bai, Yulei; Zhou, Yanzhou; He, Zhaoshui; Ye, Shuangli; Dong, Bo; Xie, Shengli

2018-01-01

The Fourier transform (FT), the nonlinear least-squares algorithm (NLSA), and eigenvalue decomposition algorithm (EDA) are used to evaluate the phase field in depth-resolved wavenumber-scanning interferometry (DRWSI). However, because the wavenumber series of the laser's output is usually accompanied by nonlinearity and mode-hop, FT, NLSA, and EDA, which are only suitable for equidistant interference data, often lead to non-negligible phase errors. In this work, a compressed-sensing method for DRWSI (CS-DRWSI) is proposed to resolve this problem. By using the randomly spaced inverse Fourier matrix and solving the underdetermined equation in the wavenumber domain, CS-DRWSI determines the nonuniform sampling and spectral leakage of the interference spectrum. Furthermore, it can evaluate interference data without prior knowledge of the object. The experimental results show that CS-DRWSI improves the depth resolution and suppresses sidelobes. It can replace the FT as a standard algorithm for DRWSI.

Atomic force microscope-assisted scanning tunneling spectroscopy under ambient conditions.

Science.gov (United States)

Vakhshouri, Amin; Hashimoto, Katsushi; Hirayama, Yoshiro

2014-12-01

We have developed a method of atomic force microscopy (AFM)-assisted scanning tunneling spectroscopy (STS) under ambient conditions. An AFM function is used for rapid access to a selected position prior to performing STS. The AFM feedback is further used to suppress vertical thermal drift of the tip-sample distance during spectroscopy, enabling flexible and stable spectroscopy measurements at room temperature. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Automated Detection of Healthy and Diseased Aortae from Images Obtained by Contrast-Enhanced CT Scan

Directory of Open Access Journals (Sweden)

Michael Gayhart

2013-01-01

Full Text Available Purpose. We developed the next stage of our computer assisted diagnosis (CAD system to aid radiologists in evaluating CT images for aortic disease by removing innocuous images and highlighting signs of aortic disease. Materials and Methods. Segmented data of patient’s contrast-enhanced CT scan was analyzed for aortic dissection and penetrating aortic ulcer (PAU. Aortic dissection was detected by checking for an abnormal shape of the aorta using edge oriented methods. PAU was recognized through abnormally high intensities with interest point operators. Results. The aortic dissection detection process had a sensitivity of 0.8218 and a specificity of 0.9907. The PAU detection process scored a sensitivity of 0.7587 and a specificity of 0.9700. Conclusion. The aortic dissection detection process and the PAU detection process were successful in removing innocuous images, but additional methods are necessary for improving recognition of images with aortic disease.

Circumvention of fluorophore photobleaching in fluorescence fluctuation experiments: a beam scanning approach.

Science.gov (United States)

Satsoura, Dmitri; Leber, Brian; Andrews, David W; Fradin, Cécile

2007-04-23

Photobleaching is a fluorophore-damaging process that commonly afflicts single-molecule fluorescence studies. It becomes an especially severe problem in fluorescence fluctuation experiments when studying slowly diffusing particles. One way to circumvent this problem is to use beam scanning to decrease the residence time of the fluorophores in the excitation volume. We report a systematic study of the effects of circular beam scanning on the photobleaching of fluorescent particles as observed in single-photon excitation fluorescence fluctuation experiments. We start by deriving a simple expression relating the average detected fluorescence to the photobleaching cross section of the fluorophores. We then perform numerical calculations of the spatial distribution of fluorescent particles in order to understand under which conditions beam scanning can prevent the formation of a photobleaching hole. To support these predictions, we show experimental results obtained for large unilamellar vesicles containing a small amount of the fluorescent lipophilic tracer DiD. We establish the required scanning radius and frequency range in order to obtain sufficient reduction of the photobleaching effect for that system. From the detected increase in fluorescence upon increase in scanning speed, we estimate the photobleaching cross section of DiD.

Bone graft viability evaluated by three phase bone scan

International Nuclear Information System (INIS)

Ljiljana Jaukovic Rajko Spaic; Marijan Novakovic; Srbislav Stosic

2004-01-01

Bone defects resulting war injury can be replaced by microvascular bone grafts from fibula. Aim: The aim of this study was to assess the value of three phase (3P) bone scintigraphy in the early detection of the bone graft complications. Method: 3P bone scans were performed in four patients (two after mandible reconstruction with micro vascular fibular bone grafts, one after fibular transplantation for ulnar and one with humeral reconstruction). First dynamic phase scan was performed immediately after iv injection of 740 MBq Tc- 99m DPD, acquiring 15 two seconds duration frames. Second, early static scan was performed during next 300 seconds, and third, delayed scan three hours later. All scans were obtained under the bone graft region. The scans were evaluated using ROI under graft region and the corresponding contra lateral area. Blood flow in graft region was determined using first phase scan, and tracer uptake in the same region was determined using second and third phase scans. Results: in all patients blood flow in graft region was particularly normal. Tracer uptake in one of two patients with mandible reconstruction was diffusely increased in graft, strongly suggesting infection; In the other patient delayed scan showed no tracer uptake in graft center .Both patients with ulnar and humeral reconstruction showed only slightly decreased tracer uptake in bone grafts. 3 phase bone scintigraphy may play a role in the evaluation of bone graft viability by predicting the infection and necrosis. (authors)

Multiresolution 3-D reconstruction from side-scan sonar images.

Science.gov (United States)

Coiras, Enrique; Petillot, Yvan; Lane, David M

2007-02-01

In this paper, a new method for the estimation of seabed elevation maps from side-scan sonar images is presented. The side-scan image formation process is represented by a Lambertian diffuse model, which is then inverted by a multiresolution optimization procedure inspired by expectation-maximization to account for the characteristics of the imaged seafloor region. On convergence of the model, approximations for seabed reflectivity, side-scan beam pattern, and seabed altitude are obtained. The performance of the system is evaluated against a real structure of known dimensions. Reconstruction results for images acquired by different sonar sensors are presented. Applications to augmented reality for the simulation of targets in sonar imagery are also discussed.

A NOVEL TECHNIQUE TO IMPROVE PHOTOMETRY IN CONFUSED IMAGES USING GRAPHS AND BAYESIAN PRIORS

International Nuclear Information System (INIS)

Safarzadeh, Mohammadtaher; Ferguson, Henry C.; Lu, Yu; Inami, Hanae; Somerville, Rachel S.

2015-01-01

We present a new technique for overcoming confusion noise in deep far-infrared Herschel space telescope images making use of prior information from shorter λ < 2 μm wavelengths. For the deepest images obtained by Herschel, the flux limit due to source confusion is about a factor of three brighter than the flux limit due to instrumental noise and (smooth) sky background. We have investigated the possibility of de-confusing simulated Herschel PACS 160 μm images by using strong Bayesian priors on the positions and weak priors on the flux of sources. We find the blended sources and group them together and simultaneously fit their fluxes. We derive the posterior probability distribution function of fluxes subject to these priors through Monte Carlo Markov Chain (MCMC) sampling by fitting the image. Assuming we can predict the FIR flux of sources based on the ultraviolet-optical part of their SEDs to within an order of magnitude, the simulations show that we can obtain reliable fluxes and uncertainties at least a factor of three fainter than the confusion noise limit of 3σ c = 2.7 mJy in our simulated PACS-160 image. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information of positions and plausible fluxes of blended sources. For Herschel, application of this technique will improve our ability to constrain the dust content in normal galaxies at high redshift

Image quality of high-resolution CT with 16-channel multidetector-row CT. Comparison between helical scan and conventional step-shoot scan

International Nuclear Information System (INIS)

Sumikawa, Hiromitsu; Johkoh, Takeshi; Koyama, Mitsuhiro

2005-01-01

The aim of this study was to evaluate the image quality of high-resolution CT (HRCT) reconstructed from volumetric data with 16-channel multidetector-row CT (MDCT). Eleven autopsy lungs that were diagnosed histopathologically were scanned by 16-channel MDCT with the step-and-shoot scan mode and three helical scan modes. Each helical mode had each size of focal spot, pitch, and time of gantry rotation. HRCT images were reconstructed from the volumetric data with each helical mode and axial sequence data. Two observers evaluated the image quality and noted the most appropriate diagnosis for each imaging. Visualization of abnormal structures with one helical mode was equal to those with axial mode, whereas those with the other two helical modes were inferior to those with axial mode (Wilcoxon signed rank test; p<0.0001). There was no significant difference in diagnostic efficacy between modes. The image quality of HRCT with appropriate helical mode is equal to that with axial mode and diagnostic efficacy is equal among all modes. These results may indicate that sufficient HRCT images can be obtained by only one helical scan without the addition of conventional axial scans. (author)

SU-F-T-173: One-Scan Protocol: Verifying the Delivery of Spot-Scanning Proton Beam

Energy Technology Data Exchange (ETDEWEB)

Chan, M; Li, J [Memorial Sloan-Kettering Cancer Center, Basking Ridge, NJ (United States); Chen, C; Mah, D [Procure Treatment Center, Somerset, NJ (United States); Tang, X [Memorial Sloan Kettering Cancer Center, West Harrison, NY (United States); Li, X [Memorial Sloan Kettering Cancer Center, Rockville Centre, NY (United States); Tang, G [Memorial Sloan Kettering Cancer Center, New York, NY (United States)

2016-06-15

Purpose: Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. Methods: We performed the calibration using an EBT3 film at depths of 18, 20, 24cm of Plastic Water exposed by a 6-level step-wedge plan on a Proteus Plus proton system (IBA, Belgium). The calibration doses ranged 65–250 cGy(RBE) for proton energies of 170–200MeV. A clinical prostate+nodes plan was used for validation. The planar doses at selected depths were measured with EBT3 films and analyzed using one-scan protocol (one-scan digitization of QA film and at least one film exposed to known dose). The Gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film, IBA MatriXX PT, versus TPS calculations were analyzed and compared. Results: The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate of ∼95% for 2%/2mm and slightly lower passing rates were obtained from an ion chamber array detector. We were able to demonstrate that the use of a proton step-wedge provided clinically acceptable results and minimized variations between film-scanner orientation, inter-scan, and scanning conditions. Furthermore, it could be derived from no more than two films exposed to known doses (one could be zero) for rescaling the master calibration curve at each depth. Conclusion: The use of a proton step-wedge for calibration of EBT3 film increases efficiency. The sensitivity of the calibration to depth variations has been explored. One-scan protocol results appear to be comparable to that of the ion chamber array detector. One author has a research grant from

[18F]-Fluoro-Deoxy-Glucose Positron Emission Tomography Scan Should Be Obtained Early in Cases of Autoimmune Encephalitis

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C. R. Newey

2016-01-01

Full Text Available Introduction. Autoimmune encephalitis (AE is a clinically challenging diagnosis with nonspecific neurological symptoms. Prompt diagnosis is important and often relies on neuroimaging. We present a case series of AE highlighting the importance of an early [18F]-fluoro-deoxy-glucose positron emission tomography (FDG-PET scan. Methods. Retrospective review of seven consecutive cases of autoimmune encephalitis. Results. All patients had both magnetic resonance imaging (MRI and FDG-PET scans. Initial clinical presentations included altered mental status and/or new onset seizures. Six cases had serum voltage-gated potassium channel (VGKC antibody and one had serum N-methyl-D-aspartate (NMDA antibody. MRI of brain showed mesial temporal lobe hyperintensity in five cases of VGKC. The other two patients with VGKC or NMDA AE had restiform body hyperintensity on MRI brain or a normal MRI, respectively. Mesial temporal lobe hypermetabolism was noted in three cases on FDG-PET, despite initial unremarkable MRI. Malignancy workup was negative in all patients. Conclusion. A high index of suspicion for AE should be maintained in patients presenting with cognitive symptoms, seizures, and limbic changes on neuroimaging. In cases with normal initial brain MRI, FDG-PET can be positive. Additionally, extralimbic hyperintensity on MRI may also be observed.

[18F]-Fluoro-Deoxy-Glucose Positron Emission Tomography Scan Should Be Obtained Early in Cases of Autoimmune Encephalitis

Science.gov (United States)

Sarwal, A.; Hantus, S.

2016-01-01

Introduction. Autoimmune encephalitis (AE) is a clinically challenging diagnosis with nonspecific neurological symptoms. Prompt diagnosis is important and often relies on neuroimaging. We present a case series of AE highlighting the importance of an early [18F]-fluoro-deoxy-glucose positron emission tomography (FDG-PET) scan. Methods. Retrospective review of seven consecutive cases of autoimmune encephalitis. Results. All patients had both magnetic resonance imaging (MRI) and FDG-PET scans. Initial clinical presentations included altered mental status and/or new onset seizures. Six cases had serum voltage-gated potassium channel (VGKC) antibody and one had serum N-methyl-D-aspartate (NMDA) antibody. MRI of brain showed mesial temporal lobe hyperintensity in five cases of VGKC. The other two patients with VGKC or NMDA AE had restiform body hyperintensity on MRI brain or a normal MRI, respectively. Mesial temporal lobe hypermetabolism was noted in three cases on FDG-PET, despite initial unremarkable MRI. Malignancy workup was negative in all patients. Conclusion. A high index of suspicion for AE should be maintained in patients presenting with cognitive symptoms, seizures, and limbic changes on neuroimaging. In cases with normal initial brain MRI, FDG-PET can be positive. Additionally, extralimbic hyperintensity on MRI may also be observed. PMID:27559482

Tin dioxide nanostructured thin films obtained through polymeric precursor method

Directory of Open Access Journals (Sweden)

Marcelo Antônio Dal Santos

2012-11-01

Full Text Available Tin dioxide (SnO2 nanostructured thin films with low proportion of defects and low roughness were produced through the systematic control of temperature and viscosity of the precursor solutions used for thin films deposition. These solutions were obtained through the citrate method and the films were deposited through the ‘dip-coating’ technique on glass substrate and after thermal treatment at 470ºC/4h, they were characterized both structurally and morphologically through the X-ray diffractometry, optic microscopy, scanning electronic microscopy, atomic force microscopy, X-ray fluorescence, UV-Vis absorption spectroscopy and X-ray excited photoelectrons spectroscopy. The film thickness was obtained through scanning electronic microscopy of the films cross-section and correlated to the proportion of Sn and Si obtained through X-ray fluorescence. X-ray diffractometry of the films revealed the presence of peaks corresponding to the SnO2 crystalline phase, overlapping a wide peak between 20 and 30º (2?, characteristic of the glass substrate. Optic microscopy, Scanning electronic microscopy and atomic force microscopy revealed homogeneous films, with low roughness, suitable to several applications such as sensors and transparent electrodes. It could be observed through the UV-Vis absorption analysis that the films presented high optical transparency and ‘band gap’ energy 4.36 eV. The X-ray excited photoelectron spectroscopy confirmed the presence of SnO2, as well as traces of the elements present in the glass substrate and residual carbon from the thermal treatment of the films.

Growth of Pd-Filled Carbon Nanotubes on the Tip of Scanning Probe Microscopy

Directory of Open Access Journals (Sweden)

Tomokazu Sakamoto

2009-01-01

Full Text Available We have synthesized Pd-filled carbon nanotubes (CNTs oriented perpendicular to Si substrates using a microwave plasma-enhanced chemical vapor deposition (MPECVD for the application of scanning probe microscopy (SPM tip. Prior to the CVD growth, Al thin film (10 nm was coated on the substrate as a buffer layer followed by depositing a 5∼40 nm-thick Pd film as a catalyst. The diameter and areal density of CNTs grown depend largely on the initial Pd thickness. Scanning electron microscopy (SEM and transmission electron microscopy (TEM images clearly show that Pd is successfully encapsulated into the CNTs, probably leading to higher conductivity. Using optimum growth conditions, Pd-filled CNTs are successfully grown on the apex of the conventional SPM cantilever.

Single scan vector prediction in selective laser melting

NARCIS (Netherlands)

Wits, Wessel Willems; Bruins, R.; Terpstra, L.; Huls, R.A.; Geijselaers, Hubertus J.M.

2015-01-01

In selective laser melting (SLM) products are built by melting layers of metal powder successively. Optimal process parameters are usually obtained by scanning single vectors and subsequently determining which settings lead to a good compromise between product density and build speed. This paper

Angiotensin-I-converting enzyme and gallium scan in noninvasive evaluation of sarcoidosis

Energy Technology Data Exchange (ETDEWEB)

Nosal, A. (Harbor General Hospital, Torrance, CA); Schleissner, L.A.; Mishkin, F.S.; Lieberman, J.

1979-03-01

Angiotensin-converting enzyme assays and gallium-scan results were obtained from 27 patients with biopsy-proven, clinically active sarcoidosis. Twenty-three of these patients had elevated converting enzyme levels, and 22 had positive gallium-scan results. Three of four patients with normal or borderline-elevated levels of angiotensin-converting enzyme also had positive gallium-scan results. Of 156 nonsarcoid patients (pulmonary and other diseases), 27 were found to have elevated serum converting enzyme levels, and 25 of these had negative gallium-scan results. These results indicate that the combination of an assay of angiotensin-converting enzyme and gallium scan increases diagnostic specificity from 83% to 99% without sacrificing sensitivity. It was concluded that the concurrent use of angiotensin-converting enzyme assay and gallium scan is of value in the diagnosis of sarcoidosis.

Angiotensin-I-converting enzyme and gallium scan in noninvasive evaluation of sarcoidosis

International Nuclear Information System (INIS)

Nosal, A.; Schleissner, L.A.; Mishkin, F.S.; Lieberman, J.

1979-01-01

Angiotensin-converting enzyme assays and gallium-scan results were obtained from 27 patients with biopsy-proven, clinically active sarcoidosis. Twenty-three of these patients had elevated converting enzyme levels, and 22 had positive gallium-scan results. Three of four patients with normal or borderline-elevated levels of angiotensin-converting enzyme also had positive gallium-scan results. Of 156 nonsarcoid patients (pulmonary and other diseases), 27 were found to have elevated serum converting enzyme levels, and 25 of these had negative gallium-scan results. These results indicate that the combination of an assay of angiotensin-converting enzyme and gallium scan increases diagnostic specificity from 83% to 99% without sacrificing sensitivity. It was concluded that the concurrent use of angiotensin-converting enzyme assay and gallium scan is of value in the diagnosis of sarcoidosis

OPtimal backlight scanning for 3D crosstalk reduction in LCD TV

DEFF Research Database (Denmark)

Burini, Nino; Shu, Xiao; Jiao, Liangbao

2013-01-01

This work presents a method to determine the optimal backlight scanning signals to minimize crosstalk for time-sequential stereoscopic 3D on LCD TV with active shutter glasses. The solution is obtained through optimization of the variables defined by a model of backlight scanning that considers...... important aspects like liquid crystal transitions and light diffusion, subject to constraints that ensure the rendition of a uniform backlight. Compared with basic backlight scanning, the proposed method can increase luminance at a given crosstalk level or reduce crosstalk at a given luminance level....

Weakly supervised semantic segmentation using fore-background priors

Science.gov (United States)

Han, Zheng; Xiao, Zhitao; Yu, Mingjun

2017-07-01

Weakly-supervised semantic segmentation is a challenge in the field of computer vision. Most previous works utilize the labels of the whole training set and thereby need the construction of a relationship graph about image labels, thus result in expensive computation. In this study, we tackle this problem from a different perspective. We proposed a novel semantic segmentation algorithm based on background priors, which avoids the construction of a huge graph in whole training dataset. Specifically, a random forest classifier is obtained using weakly supervised training data .Then semantic texton forest (STF) feature is extracted from image superpixels. Finally, a CRF based optimization algorithm is proposed. The unary potential of CRF derived from the outputting probability of random forest classifier and the robust saliency map as background prior. Experiments on the MSRC21 dataset show that the new algorithm outperforms some previous influential weakly-supervised segmentation algorithms. Furthermore, the use of efficient decision forests classifier and parallel computing of saliency map significantly accelerates the implementation.

Trends and patterns of computed tomography scan use among children in The Netherlands: 1990-2012.

Science.gov (United States)

Meulepas, Johanna M; Smets, Anne M J B; Nievelstein, Rutger A J; Gradowska, Patrycja; Verbeke, Jonathan; Holscher, Herma C; Rutten, Matthieu J C M; Kieft, Mariëtte; Ronckers, Cécile M; Hauptmann, Michael

2017-06-01

To evaluate trends and patterns in CT usage among children (aged 0-17 years) in The Netherlands during the period 1990-2012. Lists of electronically archived paediatric CT scans were requested from the Radiology Information Systems (RIS) of Dutch hospitals which reported >10 paediatric CT scans annually in a survey conducted in 2010. Data included patient identification, birth date, gender, scan date and body part scanned. For non-participating hospitals and for years prior to electronic archiving in some participating hospitals, data were imputed by calendar year and hospital type (academic, general with Netherlands increased from 7,731 in 1990 to 26,023 in 2012. More than 70 % of all scans were of the head and neck. During the last decade, substantial increases of more than 5 % per year were observed in general hospitals with fewer than 500 beds and among children aged 10 years or older. The estimated number of paediatric CT scans has more than tripled in The Netherlands during the last two decades. • Paediatric CT in The Netherlands has tripled during the last two decades. • The number of paediatric CTs increased through 2012 in general hospitals. • Paediatric CTs continued to increase among children aged 10 years or older.

Construction of a four tip scanning tunneling microscope/scanning electron microscope combination and conductivity measurements of silicide nanowires

International Nuclear Information System (INIS)

Zubkov, Evgeniy

2013-01-01

In this work the combination of a four-tip scanning tunneling microscope with a scanning electron microscope is presented. By means of this apparatus it is possible to perform the conductivity measurements on the in-situ prepared nanostructures in ultra-high vacuum. With the aid of a scanning electron microscope (SEM), it becomes possible to position the tunneling tips of the four-tip scanning tunneling microscope (STM), so that an arrangement for a four-point probe measurement on nanostructures can be obtained. The STM head was built according to the novel coaxial Beetle concept. This concept allows on the one hand, a very compact arrangement of the components of the STM and on the other hand, the new-built STM head has a good mechanical stability, in order to achieve atomic resolution with all four STM units. The atomic resolution of the STM units was confirmed by scanning a Si(111)-7 x 7 surface. The thermal drift during the STM operation, as well as the resonant frequencies of the mechanical structure of the STM head, were determined. The scanning electron microscope allows the precise and safe navigation of the tunneling tips on the sample surface. Multi tip spectroscopy with up to four STM units can be performed synchronously. To demonstrate the capabilities of the new-built apparatus the conductivity measurements were carried out on metallic yttrium silicide nanowires. The nanowires were prepared by the in-situ deposition of yttrium on a heated Si(110) sample surface. Current-voltage curves were recorded on the nanowires and on the wetting layer in-between. The curves indicate an existence of the Schottky barrier between the yttrium silicide nanowires and the silicon bulk. By means of the two-tip measurements with a gate, the insulating property of the Schottky barrier has been confirmed. Using this Schottky barrier, it is possible to limit the current to the nanowire and to prevent it from flowing through the silicon bulk. A four-tip resistance measurement

Uniform irradiation system using beam scanning method for cyclotron

International Nuclear Information System (INIS)

Agematsu, Takashi; Okumura, Susumu; Arakawa, Kazuo

1994-03-01

JAERI AVF-cyclotron is equipped with an ion beam scanner for large area irradiation. The two-dimensional fluence distribution of ion beam obtained using cellulose triacetate film dosimeter was not uniform. This is resulted from the distortion of excitation current for electromagnet of the scanner. So, the beam scanning condition, i.e., the relation between the ion species, the beam profile and the scanning width, was extremely limited to make a good uniformity. We have developed a beam scanning simulator to get fluence distributions by calculation and then compared the simulated distributions with the measured ones. It was revealed that the both of them are in good agreement and the beam scanning condition to get good uniformity was led by using this simulator. On the basis of these results, the power supply of scanner was improved. A good uniformity of beam distribution was available. (author)

CT-scanning in otolaryngology, 2

International Nuclear Information System (INIS)

Kusakari, Jun; Endo, Satomi; Hara, Akira

1982-01-01

Combined computerized tomography-sialography was performed in 28 patients with parotid tumors. Sialography was performed in the usual fashion. After confirming the presence of the contrast material within the parotid gland by X-ray, 4 to 5 scannings were done at the width of 10 mm below Repid's base line. With this procedure, the parotid gland was clearly demonstrated and the location of the tumor was shown as a shadow defect. Although the nature of the tumor, especially whether it was malignant or benign was difficult to predict, the CT-findings regarding the size and location of the tumor were completely coincident with the operative findings in all the cases. Accurate appraisal of the relation between the tumor and the facial nerve was possible in all but two cases. The preoperative information obtained from CT-scanning is extremely useful in the case of parotid tumor surgery. (author)

Doppler ultrasound scan during normal gestation: umbilical circulation

International Nuclear Information System (INIS)

Ruiz, T.; Sabate, J.; Martinez-Benavides, M. M.; Sanchez-Ramos, J.

2002-01-01

To determine normal umbilical circulation patterns by means of Doppler ultrasound scan in a healthy gestating population without risk factors and with normal perinatal results, and to evaluate any occurring modifications relative to gestational age by obtaining records kept during pregnancy. One hundred and sixteen pregnant women carrying a single fetus have been studied. These women had no risk factors, with both clinical and analytical controls, as well as ultrasound scans, all being normal. There were performed a total of 193 Doppler ultrasound scans between weeks 15 and 41 of gestation, with blood-flow analysis in the arteries and vein of the umbilical cord. The obtained information was correlated with parameters that evaluate fetal well-being (fetal monitoring and/or oxytocin test) and perinatal result (delivery type, birth weight, Apgar score). Statistical analysis was performed with the programs SPSS 6.0.1 for Windows and EPIINFO 6.0.4. With pulsed Doppler, the umbilical artery in all cases demonstrated a biphasic morphology with systolic and diastolic components and without retrograde blood flow. As the gestation period increased, there was observed a progressive decrease in resistance along with an increase in blood-flow velocity during the diastolic phase. The Doppler ultrasound scan is a non-invasive method that permits the hemodynamic study of umbilical blood circulation. A knowledge of normal blood-flow signal morphology, as well as of the normal values for Doppler indices in relation to gestational age would permit us to utilize this method in high-risk pregnancies. (Author) 30 refs

Signal Processing Effects for Ultrasonic Guided Wave Scanning of Composites

International Nuclear Information System (INIS)

Roth, D.J.; Cosgriff, L.M.; Martin, R.E.; Burns, E.A.; Teemer, L.

2005-01-01

The goal of this ongoing work is to optimize experimental variables for a guided wave scanning method to obtain the most revealing and accurate images of defect conditions in composite materials. This study focuses on signal processing effects involved in forming guided wave scan images. Signal processing is involved at two basic levels for deriving ultrasonic guided wave scan images. At the primary level, NASA GRC has developed algorithms to extract over 30 parameters from the multimode signal and its power spectral density. At the secondary level, there are many variables for which values must be chosen that affect actual computation of these parameters. In this study, a ceramic matrix composite sample having a delamination is characterized using the ultrasonic guided wave scan method. Energy balance and decay rate parameters of the guided wave at each scan location are calculated to form images. These images are compared with ultrasonic c-scan and thermography images. The effect of the time portion of the waveform processed on image quality is assessed by comparing with images formed using the total waveform acquired

Scan-guided fine needle aspiration biopsy in malignant hepatic disease

International Nuclear Information System (INIS)

Johansen, P.; Svendsen, K.N.

1978-01-01

The method of scan-guided fine needle aspiration biopsy of the liver is described, and the diagnostic value of this combined method in the diagnosis of malignant hepatic disease is evaluated in 83 confirmed cases, showing a specificity of 100% and a sensitivity of 94%. The combined method is compared to liver scanning alone and to Menghini biopsy. Different methods for the diagnosis of malignant hepatic disease are discussed, and it is concluded that scan-guided fine needle aspiration biopsy has a diagnostic value only obtainable otherwise by a combination of liver scanning and biopsy during laparoscopy. Cytologic features in the two most common tumor types in this study, i.e., metastatic colonic adenocarcinoma and hepatocarcinoma, are presented along with a brief discussion of the specificity of the cytologic diagnosis of hepatocarcinoma

Interactive lung segmentation in abnormal human and animal chest CT scans

International Nuclear Information System (INIS)

Kockelkorn, Thessa T. J. P.; Viergever, Max A.; Schaefer-Prokop, Cornelia M.; Bozovic, Gracijela; Muñoz-Barrutia, Arrate; Rikxoort, Eva M. van; Brown, Matthew S.; Jong, Pim A. de; Ginneken, Bram van

2014-01-01

challenging chest CT images. Both systems do not require prior knowledge of the scans under consideration and work on a variety of scans

Surface scanning through a cylindrical tank of coupling fluid for clinical microwave breast imaging exams

International Nuclear Information System (INIS)

Pallone, Matthew J.; Meaney, Paul M.; Paulsen, Keith D.

2012-01-01

Purpose: Microwave tomographic image quality can be improved significantly with prior knowledge of the breast surface geometry. The authors have developed a novel laser scanning system capable of accurately recovering surface renderings of breast-shaped phantoms immersed within a cylindrical tank of coupling fluid which resides completely external to the tank (and the aqueous environment) and overcomes the challenges associated with the optical distortions caused by refraction from the air, tank wall, and liquid bath interfaces. Methods: The scanner utilizes two laser line generators and a small CCD camera mounted concentrically on a rotating gantry about the microwave imaging tank. Various calibration methods were considered for optimizing the accuracy of the scanner in the presence of the optical distortions including traditional ray tracing and image registration approaches. In this paper, the authors describe the construction and operation of the laser scanner, compare the efficacy of several calibration methods—including analytical ray tracing and piecewise linear, polynomial, locally weighted mean, and thin-plate-spline (TPS) image registrations—and report outcomes from preliminary phantom experiments. Results: The results show that errors in calibrating camera angles and position prevented analytical ray tracing from achieving submillimeter accuracy in the surface renderings obtained from our scanner configuration. Conversely, calibration by image registration reliably attained mean surface errors of less than 0.5 mm depending on the geometric complexity of the object scanned. While each of the image registration approaches outperformed the ray tracing strategy, the authors found global polynomial methods produced the best compromise between average surface error and scanner robustness. Conclusions: The laser scanning system provides a fast and accurate method of three dimensional surface capture in the aqueous environment commonly found in microwave

Models for Validation of Prior Learning (VPL)

DEFF Research Database (Denmark)

Ehlers, Søren

The national policies for the education/training of adults are in the 21st century highly influenced by proposals which are formulated and promoted by The European Union (EU) as well as other transnational players and this shift in policy making has consequences. One is that ideas which in the past...... would have been categorized as utopian can become realpolitik. Validation of Prior Learning (VPL) was in Europe mainly regarded as utopian while universities in the United States of America (USA) were developing ways to obtain credits to those students which was coming with experiences from working life....

Nanoscale electrical property studies of individual GeSi quantum rings by conductive scanning probe microscopy.

Science.gov (United States)

Lv, Yi; Cui, Jian; Jiang, Zuimin M; Yang, Xinju

2012-11-29

The nanoscale electrical properties of individual self-assembled GeSi quantum rings (QRs) were studied by scanning probe microscopy-based techniques. The surface potential distributions of individual GeSi QRs are obtained by scanning Kelvin microscopy (SKM). Ring-shaped work function distributions are observed, presenting that the QRs' rim has a larger work function than the QRs' central hole. By combining the SKM results with those obtained by conductive atomic force microscopy and scanning capacitance microscopy, the correlations between the surface potential, conductance, and carrier density distributions are revealed, and a possible interpretation for the QRs' conductance distributions is suggested.

Chromosomal differences between acute nonlymphocytic leukemia in patients with prior solid tumors and prior hematologic malignancies. A study of 14 cases with prior breast cancer

International Nuclear Information System (INIS)

Mamuris, Z.; Dumont, J.; Dutrillaux, B.; Aurias, A.

1989-01-01

A cytogenetic study of 14 patients with secondary acute nonlymphocytic leukemia (S-ANLL) with prior treatment for breast cancer is reported. The chromosomes recurrently involved in numerical or structural anomalies are chromosomes 7, 5, 17, and 11, in decreasing order of frequency. The distribution of the anomalies detected in this sample of patients is similar to that observed in published cases with prior breast or other solid tumors, though anomalies of chromosome 11 were not pointed out, but it significantly differs from that of the S-ANLL with prior hematologic malignancies. This difference is principally due to a higher involvement of chromosome 7 in patients with prior hematologic malignancies and of chromosomes 11 and 17 in patients with prior solid tumors. A genetic determinism involving abnormal recessive alleles located on chromosomes 5, 7, 11, and 17 uncovered by deletions of the normal homologs may be a cause of S-ANLL. The difference between patients with prior hematologic malignancies or solid tumors may be explained by different constitutional mutations of recessive genes in the two groups of patients

Limited-angle multi-energy CT using joint clustering prior and sparsity regularization

Science.gov (United States)

Zhang, Huayu; Xing, Yuxiang

2016-03-01

In this article, we present an easy-to-implement Multi-energy CT scanning strategy and a corresponding reconstruction method, which facilitate spectral CT imaging by improving the data efficiency the number-of-energy- channel fold without introducing visible limited-angle artifacts caused by reducing projection views. Leveraging the structure coherence at different energies, we first pre-reconstruct a prior structure information image using projection data from all energy channels. Then, we perform a k-means clustering on the prior image to generate a sparse dictionary representation for the image, which severs as a structure information constraint. We com- bine this constraint with conventional compressed sensing method and proposed a new model which we referred as Joint Clustering Prior and Sparsity Regularization (CPSR). CPSR is a convex problem and we solve it by Alternating Direction Method of Multipliers (ADMM). We verify our CPSR reconstruction method with a numerical simulation experiment. A dental phantom with complicate structures of teeth and soft tissues is used. X-ray beams from three spectra of different peak energies (120kVp, 90kVp, 60kVp) irradiate the phantom to form tri-energy projections. Projection data covering only 75◦ from each energy spectrum are collected for reconstruction. Independent reconstruction for each energy will cause severe limited-angle artifacts even with the help of compressed sensing approaches. Our CPSR provides us with images free of the limited-angle artifact. All edge details are well preserved in our experimental study.

The relevance of electrostatics for scanning-gate microscopy

International Nuclear Information System (INIS)

Schnez, S; Guettinger, J; Stampfer, C; Ensslin, K; Ihn, T

2011-01-01

Scanning-probe techniques have been developed to extract local information from a given physical system. In particular, conductance maps obtained by means of scanning-gate microscopy (SGM), where a conducting tip of an atomic-force microscope is used as a local and movable gate, seem to present an intuitive picture of the underlying physical processes. Here, we argue that the interpretation of such images is complex and not very intuitive under certain circumstances: scanning a graphene quantum dot (QD) in the Coulomb-blockaded regime, we observe an apparent shift of features in scanning-gate images as a function of gate voltages, which cannot be a real shift of the physical system. Furthermore, we demonstrate the appearance of more than one set of Coulomb rings arising from the graphene QD. We attribute these effects to screening between the metallic tip and the gates. Our results are relevant for SGM on any kind of nanostructure, but are of particular importance for nanostructures that are not covered with a dielectric, e.g. graphene or carbon nanotube structures.

Stereoscopic and photometric surface reconstruction in scanning electron microscopy

International Nuclear Information System (INIS)

Scherer, S.

2000-01-01

The scanning electron microscope (SEM) is one of the most important devices to examine microscopic structures as it offers images of a high contrast range with a large depth of focus. Nevertheless, three-dimensional measurements, as desired in fracture mechanics, have previously not been accomplished. This work presents a system for automatic, robust and dense surface reconstruction in scanning electron microscopy combining new approaches in shape from stereo and shape from photometric stereo. The basic theoretical assumption for a known adaptive window algorithm is shown not to hold in scanning electron microscopy. A constraint derived from this observation yields a new, simplified, hence faster calculation of the adaptive window. The correlation measure itself is obtained by a new ordinal measure coefficient. Shape from photometric stereo in the SEM is formulated by relating the image formation process with conventional photography. An iterative photometric ratio reconstruction is invented based on photometric ratios of backscatter electron images. The performance of the proposed system is evaluated using ground truth data obtained by three alternative shape recovery devices. Most experiments showed relative height accuracy within the tolerances of the alternative devices. (author)

Unit-cell refinement from powder diffraction scans

International Nuclear Information System (INIS)

Pawley, G.S.

1981-01-01

A procedure for the refinement of the crystal unit cell from a powder diffraction scan is presented. In this procedure knowledge of the crystal structure is not required, and at the end of the refinement a list of indexed intensities is produced. This list may well be usable as the starting point for the application of direct methods. The problems of least-squares ill-conditioning due to overlapping reflections are overcome by constraints. An example using decafluorocyclohexene, C 6 F 10 , shows the quality of fit obtained in a case which may even be a false minimum. The method should become more relevant as powder scans of improved resolution become available, through the use of pulsed neutron sources. (Auth.)

Atomic physics with the scanning tunneling microscope

International Nuclear Information System (INIS)

Kleber, M.; Bracher, C.; Riza, M.

1999-01-01

Backscattering of atomic beams above a given surface yields information similar to the one obtained from scanning the same surface with a scanning tunneling microscope (STM): In both cases the experimentally accessible quantity is the local density of states (LDOS) n(r,E) of the surface. For the case of backscattering, the LDOS at the turning point of the atom is an important ingredient of the potential between atom and surface. In experiments performed with an STM, the LDOS at the apex of an atomically sharp tip can be determined directly. Probing surfaces locally by an STM allows for the study of basic phenomena in atomic physics, with tunneling of electrons in three dimensions being a central issue

Accommodating Uncertainty in Prior Distributions

Energy Technology Data Exchange (ETDEWEB)

Picard, Richard Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vander Wiel, Scott Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-01-19

A fundamental premise of Bayesian methodology is that a priori information is accurately summarized by a single, precisely de ned prior distribution. In many cases, especially involving informative priors, this premise is false, and the (mis)application of Bayes methods produces posterior quantities whose apparent precisions are highly misleading. We examine the implications of uncertainty in prior distributions, and present graphical methods for dealing with them.

Comparison of digital scanning and polyvinyl siloxane impression techniques by dental students: instructional efficiency and attitudes towards technology.

Science.gov (United States)

Marti, A M; Harris, B T; Metz, M J; Morton, D; Scarfe, W C; Metz, C J; Lin, W-S

2017-08-01

With increasing use of digital scanning with restorative procedures in the dental office, it becomes necessary that educational institutions adopt instructional methodology for introducing this technology together with conventional impression techniques. To compare the time differences between instructing dental students on digital scanning (DS) (LAVA C.O.S. digital impression system) and a conventional impression technique (CI) (polyvinyl siloxane), and to compare students' attitudes and beliefs towards both techniques. Volunteer sophomore dental students (n = 25) with no prior experience in clinical impressions were recruited and IRB consent obtained. Participants responded to a pre-and post-exposure questionnaire. Participants were instructed on the use of both DS and CI for a single tooth full coverage crown restoration using a consecutive sequence of video lecture, investigator-led demonstration and independent impression exercise. The time necessary for each step (minutes) was recorded. Statistical significance was calculated using dependent t-tests (time measurements) and 2-sample Mann-Whitney (questionnaire responses). The time spent teaching students was greater for DS than CI for video lecture (15.95 and 10.07 min, P = 0.0000), demonstration time (9.06 and 4.70 min, P = 0.0000) and impression time (18.17 and 8.59 min, P = 0.0000). Prior to the instruction and practice, students considered themselves more familiar with CI (3.96) than DS (1.96) (P = 0.0000). After the instruction and practice, participants reported CI technique proved significantly easier than expected (pre-instruction: 3.52 and post-instruction: 4.08, P = 0.002). However, overall participants' perception of ease of use for DS was not influenced by this instruction and practice experience (pre-instruction: 3.84 and post-instruction: 3.56, P = 0.106). Despite the results, 96% of participants expressed an expectation that DS will become their predominant impression technique during their

Isotope scanning for tumor localization

Energy Technology Data Exchange (ETDEWEB)

NONE

1961-09-15

At the request of the Government of the United Arab Republic, the Agency provided the services of an expert for the establishment in the UAR of a tumor localization program using photoscanning techniques and appropriate radioactive tracers. Photoscanning is a recently developed technique whereby the differences in isotope concentrations are enhanced on the record, and this facilitates the interpretation of the record. A variety of brain tumors were located, using a suitable radioactive tracer (Hg-203 - labelled Neohydrin) obtained from the USA. In some other investigations, processes in the kidney were scanned. Further, radioactive gold was used to demonstrate the normal and pathological spleen and liver and these tests showed various types of space occupying lesions resulting from malignancy and the parasitic infections endemic to the area. While the localization of brain tumors by scanning techniques is extremely useful, it does not always establish the precise extent of the tumor which should be known at the time of surgery. Dr. Bender, therefore, thought it advisable to instruct personnel in the use of what is known as an in-vivo needle scintillation probe - a technique for the investigation of the isotope concentration in a particular tissue during operation. The necessary instrument was obtained for this purpose and demonstrations were given; one patient was examined in this way at the time of surgery at the University of Alexandria Hospital.

Obtaining of ceramics biphasic dense and porous

International Nuclear Information System (INIS)

Pallone, E.M.J.A.; Rigo, E.C.S.; Fraga, A.F.

2010-01-01

Among the bioceramic hydroxyapatite (HAP) and beta-tricalcium phosphate (beta-TCP) are materials commonly used in biomedical field. Their combined properties result in a material with absorbable and at the same time with bioactive surface. Called biphasic ceramics such materials respond more quickly when exposed to physiological environment. In this work, powders of HAP/beta-TCP were obtained by chemical precipitation. After obtaining the post-phase was added at a ratio of 0, 15% and 30w% aqueous solutions of corn starch in order to obtain porous bodies. After mixing the resulting solutions were dried, resigned in tablet form and sintered at 1300 deg C. The initial powder was characterized by X-ray diffraction with Rietveld refinement to quantify the phases present. Bodies-of-evidence has been characterized by calculating the bulk density, X-ray diffraction (XRD), scanning electron microscopy and diametral compression. (author)

Diagnosis of gynecologic pelvic masses by CT scans

International Nuclear Information System (INIS)

Ito, Hisao; Kubo, Atsushi; Takagi, Yaeko; Kinoshita, Fumio; Maekawa, Akira.

1981-01-01

Two hundred eighty four patients with gynecologic pelvic masses were evaluated with CT scans. Of the patients, 196 had subsequent surgical determination of abnormalities and pathological proof of diagnosis was obtained. Only these 196 patients were included in this study. The CT scans could provide correct diagnosis in 113 of 114 (99%) patients with benign uterine tumor and in all (100%) patients with either serous cystadenoma or dermoid cyst. However, evaluation of mucinous cystadenoma (44%) and endometriosis cyst (37%) by CT scan has some limitations. It was difficult to differentiate mucinous cystadenoma from ovarian carcinoma, because both lesions had partial multiloculation and solid-like areas in the cyst. The CT findings of endometriosis cyst had similarity with serous cystadenoma, and 5 of 8 patients with this disease were diagnosed as serous cystadenoma. Ovarian fibroma and endometrial cancer were also not determined by CT scans. CT identified 87% of patients with ovarian cancer, while false positive rate of this disease was 38% (8/21). In 6 of 13 patients with both of leiomyoma and ovarian cyst, CT was able to demonstrate ovarian lesions that were overlooked by bimanual examinations. The role of CT scanning in our clinical practice is discussed. (author)

Bone scanning with technetium /sup 99m/Tc polyphosphate in tuberculous osteomyelitis

Energy Technology Data Exchange (ETDEWEB)

Fanning, A; Dierich, H; Lentle, B

1974-09-01

Bone scans in 7 patients with tuberculosis have indicated bony involvement in 3. This was unsuspected in 2 and in all 3 radiographic correlation has been obtained. The present ready availability of more modern bone scanning agents and their safety is important to remember. They provide an elegant and sensitive, if non-specific, index of bone disease.

A Small Crack Length Evaluation Technique by Electronic Scanning

International Nuclear Information System (INIS)

Cho, Yong Sang; Kim, Jae Hoon

2009-01-01

The results of crack evaluation by conventional UT(Ultrasonic Test)is highly depend on the inspector's experience or knowledge of ultrasound. Phased array UT system and its application methods for small crack length evaluation will be a good alternative method which overcome present UT weakness. This study was aimed at checking the accuracy of crack length evaluation method by electronic scanning and discuss about characteristics of electronic scanning for crack length evaluation. Especially ultrasonic phased array with electronic scan technique was used in carrying out both sizing and detect ability of crack as its length changes. The response of ultrasonic phased array was analyzed to obtain the special method of determining crack length without moving the transducer and detectability of crack minimal length and depth from the material. A method of crack length determining by electronic scanning for the small crack is very real method which has it's accuracy and verify the effectiveness of method compared to a conventional crack length determination

Identifying recombinants in human and primate immunodeficiency virus sequence alignments using quartet scanning

Directory of Open Access Journals (Sweden)

Martin Darren P

2009-04-01

Full Text Available Abstract Background Recombination has a profound impact on the evolution of viruses, but characterizing recombination patterns in molecular sequences remains a challenging endeavor. Despite its importance in molecular evolutionary studies, identifying the sequences that exhibit such patterns has received comparatively less attention in the recombination detection framework. Here, we extend a quartet-mapping based recombination detection method to enable identification of recombinant sequences without prior specifications of either query and reference sequences. Through simulations we evaluate different recombinant identification statistics and significance tests. We compare the quartet approach with triplet-based methods that employ additional heuristic tests to identify parental and recombinant sequences. Results Analysis of phylogenetic simulations reveal that identifying the descendents of relatively old recombination events is a challenging task for all methods available, and that quartet scanning performs relatively well compared to the triplet based methods. The use of quartet scanning is further demonstrated by analyzing both well-established and putative HIV-1 recombinant strains. In agreement with recent findings, we provide evidence that the presumed circulating recombinant CRF02_AG is a 'pure' lineage, whereas the presumed parental lineage subtype G has a recombinant origin. We also demonstrate HIV-1 intrasubtype recombination, confirm the hybrid origin of SIV in chimpanzees and further disentangle the recombinant history of SIV lineages in a primate immunodeficiency virus data set. Conclusion Quartet scanning makes a valuable addition to triplet-based methods for identifying recombinant sequences without prior specifications of either query and reference sequences. The new method is available in the VisRD v.3.0 package http://www.cmp.uea.ac.uk/~vlm/visrd.

Focal depth measurement of scanning helium ion microscope

International Nuclear Information System (INIS)

Guo, Hongxuan; Itoh, Hiroshi; Wang, Chunmei; Zhang, Han; Fujita, Daisuke

2014-01-01

When facing the challenges of critical dimension measurement of complicated nanostructures, such as of the three dimension integrated circuit, characterization of the focal depth of microscopes is important. In this Letter, we developed a method for characterizing the focal depth of a scanning helium ion microscope (HIM) by using an atomic force microscope tip characterizer (ATC). The ATC was tilted in a sample chamber at an angle to the scanning plan. Secondary electron images (SEIs) were obtained at different positions of the ATC. The edge resolution of the SEIs shows the nominal diameters of the helium ion beam at different focal levels. With this method, the nominal shapes of the helium ion beams were obtained with different apertures. Our results show that a small aperture is necessary to get a high spatial resolution and high depth of field images with HIM. This work provides a method for characterizing and improving the performance of HIM.

Vibration compensated high-resolution scanning white-light Linnik-interferometer

Science.gov (United States)

Tereschenko, Stanislav; Lehmann, Peter; Gollor, Pascal; Kuehnhold, Peter

2017-06-01

We present a high-resolution Linnik scanning white-light interferometer (SWLI) with integrated distance measuring interferometer (DMI) for close-to-machine applications in the presence of environmental vibrations. The distance, measured by DMI during the depth-scan, is used for vibration compensation of SWLI signals. The reconstruction of the white-light interference signals takes place after measurement by reordering the captured images in accordance with their real positions obtained by the DMI and subsequent trigonometrical approximation. This system is the further development of our previously presented Michelson-interferometer. We are able to compensate for arbitrary vibrations with frequencies up to several kilohertz and amplitudes in the lower micrometer range. Completely distorted SWLI signals can be reconstructed and the surface topography can be obtained with high accuracy. We demonstrate the feasibility of the method by examples of practical measurements with and without vibrational disturbances.

Comparison of supine, upright, and prone positions for liver scans

International Nuclear Information System (INIS)

Harolds, J.A.; Brill, A.B.; Patton, J.A.; Touya, J.J.

1983-01-01

We compared liver scan interpretations based on anterior images obtained in the upright, prone, and supine positions. Receiver-operating-characteristic curves were generated for three well trained observers. Results showed that reading the three different views together was more accurate than the reading of any individual image. Furthermore, interpretations based on either the prone or upright view were superior to those using the supine view alone. The prone and upright views should be used more often in liver scanning

High-speed X-ray phase tomography with Talbot interferometer and fringe scanning method

International Nuclear Information System (INIS)

Kibayashi, Shunsuke; Harasse, Sébastien; Yashiro, Wataru; Momose, Atsushi

2012-01-01

High-speed X-ray phase tomography based on the Fourier-transform method has been demonstrated with an X-ray Talbot interferometer using white synchrotron radiation. We report the experimental results of high-speed X-ray phase tomography with fringe-scanning method instead of Fourier-transform method to improve spatial resolution without a considerable increase of scan time. To apply fringe-scanning method to high speed tomography, we tested a scan that is a synchronous combination of one-way continuous movements of the sample rotation and the grating displacement. When this scanning method was combined with X-ray phase tomography, we were able to obtain a scan time of 5 s. A comparison of the image quality derived with the conventional approach and with the proposed approach using the fringe-scanning method showed that the latter had better spatial resolution.

Multiple-scanning-probe tunneling microscope with nanoscale positional recognition function.

Science.gov (United States)

Higuchi, Seiji; Kuramochi, Hiromi; Laurent, Olivier; Komatsubara, Takashi; Machida, Shinichi; Aono, Masakazu; Obori, Kenichi; Nakayama, Tomonobu

2010-07-01

Over the past decade, multiple-scanning-probe microscope systems with independently controlled probes have been developed for nanoscale electrical measurements. We developed a quadruple-scanning-probe tunneling microscope (QSPTM) that can determine and control the probe position through scanning-probe imaging. The difficulty of operating multiple probes with submicrometer precision drastically increases with the number of probes. To solve problems such as determining the relative positions of the probes and avoiding of contact between the probes, we adopted sample-scanning methods to obtain four images simultaneously and developed an original control system for QSPTM operation with a function of automatic positional recognition. These improvements make the QSPTM a more practical and useful instrument since four images can now be reliably produced, and consequently the positioning of the four probes becomes easier owing to the reduced chance of accidental contact between the probes.

SU-G-IeP3-08: Image Reconstruction for Scanning Imaging System Based On Shape-Modulated Point Spreading Function

Energy Technology Data Exchange (ETDEWEB)

Wang, Ruixing; Yang, LV [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha, Hunan (China); Xu, Kele [College of Electronical Science and Engineering, National University of Defense Technology, Changsha, Hunan (China); Zhu, Li [Institute of Electrostatic and Electromagnetic Protection, Mechanical Engineering College, Shijiazhuang, Hebei (China)

2016-06-15

Purpose: Deconvolution is a widely used tool in the field of image reconstruction algorithm when the linear imaging system has been blurred by the imperfect system transfer function. However, due to the nature of Gaussian-liked distribution for point spread function (PSF), the components with coherent high frequency in the image are hard to restored in most of the previous scanning imaging system, even the relatively accurate PSF is acquired. We propose a novel method for deconvolution of images which are obtained by using shape-modulated PSF. Methods: We use two different types of PSF - Gaussian shape and donut shape - to convolute the original image in order to simulate the process of scanning imaging. By employing deconvolution of the two images with corresponding given priors, the image quality of the deblurred images are compared. Then we find the critical size of the donut shape compared with the Gaussian shape which has similar deconvolution results. Through calculation of tightened focusing process using radially polarized beam, such size of donut is achievable under same conditions. Results: The effects of different relative size of donut and Gaussian shapes are investigated. When the full width at half maximum (FWHM) ratio of donut and Gaussian shape is set about 1.83, similar resolution results are obtained through our deconvolution method. Decreasing the size of donut will favor the deconvolution method. A mask with both amplitude and phase modulation is used to create a donut-shaped PSF compared with the non-modulated Gaussian PSF. Donut with size smaller than our critical value is obtained. Conclusion: The utility of donutshaped PSF are proved useful and achievable in the imaging and deconvolution processing, which is expected to have potential practical applications in high resolution imaging for biological samples.

Novel low-dose imaging technique for characterizing atomic structures through scanning transmission electron microscope

Science.gov (United States)

Su, Chia-Ping; Syu, Wei-Jhe; Hsiao, Chien-Nan; Lai, Ping-Shan; Chen, Chien-Chun

2017-08-01

To investigate dislocations or heterostructures across interfaces is now of great interest to condensed matter and materials scientists. With the advances in aberration-corrected electron optics, the scanning transmission electron microscope has demonstrated its excellent capability of characterizing atomic structures within nanomaterials, and well-resolved atomic-resolution images can be obtained through long-exposure data acquisition. However, the sample drifting, carbon contamination, and radiation damage hinder further analysis, such as deriving three-dimensional (3D) structures from a series of images. In this study, a method for obtaining atomic-resolution images with significantly reduced exposure time was developed, using which an original high-resolution image with approximately one tenth the electron dose can be obtained by combining a fast-scan high-magnification image and a slow-scan low-magnification image. The feasibility of obtaining 3D atomic structures using the proposed approach was demonstrated through multislice simulation. Finally, the feasibility and accuracy of image restoration were experimentally verified. This general method cannot only apply to electron microscopy but also benefit to image radiation-sensitive materials using various light sources.

Head CT scan

Science.gov (United States)

... scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - brain ... head size in children Changes in thinking or behavior Fainting Headache, when you have certain other signs ...

Computer-aided analysis of digital dental impressions obtained from intraoral and extraoral scanners.

Science.gov (United States)

Bohner, Lauren Oliveira Lima; De Luca Canto, Graziela; Marció, Bruno Silva; Laganá, Dalva Cruz; Sesma, Newton; Tortamano Neto, Pedro

2017-11-01

The internal and marginal adaptation of a computer-aided design and computer-aided manufacturing (CAD-CAM) prosthesis relies on the quality of the 3-dimensional image. The quality of imaging systems requires evaluation. The purpose of this in vitro study was to evaluate and compare the trueness of intraoral and extraoral scanners in scanning prepared teeth. Ten acrylic resin teeth to be used as a reference dataset were prepared according to standard guidelines and scanned with an industrial computed tomography system. Data were acquired with 4 scanner devices (n=10): the Trios intraoral scanner (TIS), the D250 extraoral scanner (DES), the Cerec Bluecam intraoral scanner (CBIS), and the Cerec InEosX5 extraoral scanner (CIES). For intraoral scanners, each tooth was digitized individually. Extraoral scanning was obtained from dental casts of each prepared tooth. The discrepancy between each scan and its respective reference model was obtained by deviation analysis (μm) and volume/area difference (μm). Statistical analysis was performed using linear models for repeated measurement factors test and 1-way ANOVA (α=.05). No significant differences in deviation values were found among scanners. For CBIS and CIES, the deviation was significantly higher (PDentistry. Published by Elsevier Inc. All rights reserved.

Heart PET scan

Science.gov (United States)

... nuclear medicine scan; Heart positron emission tomography; Myocardial PET scan ... A PET scan requires a small amount of radioactive material (tracer). This tracer is given through a vein (IV), ...

Dose profile study in head CT scans using a male anthropomorphic phantom

International Nuclear Information System (INIS)

Gomez, Alvaro M.L.; Santana, Priscila do C.; Mourao, Arnaldo P.

2017-01-01

Computed tomography (CT) test is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in the patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. An anthropomorphic adult male phantom was used and radiochromic film strips were placed to measure the absorbed dose deposited in areas such as the lens, thyroid and pituitary for study of dose deposited in these important areas containing high radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans. (author)

Dose profile study in head CT scans using a male anthropomorphic phantom

Energy Technology Data Exchange (ETDEWEB)

Gomez, Alvaro M.L.; Santana, Priscila do C.; Mourao, Arnaldo P., E-mail: amlgphys@gmail.com, E-mail: pridili@gmail.com, E-mail: apratabhz@gmail.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear; Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)

2017-11-01

Computed tomography (CT) test is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in the patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. An anthropomorphic adult male phantom was used and radiochromic film strips were placed to measure the absorbed dose deposited in areas such as the lens, thyroid and pituitary for study of dose deposited in these important areas containing high radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans. (author)

Parameter estimation of multivariate multiple regression model using bayesian with non-informative Jeffreys’ prior distribution

Science.gov (United States)

Saputro, D. R. S.; Amalia, F.; Widyaningsih, P.; Affan, R. C.

2018-05-01

Bayesian method is a method that can be used to estimate the parameters of multivariate multiple regression model. Bayesian method has two distributions, there are prior and posterior distributions. Posterior distribution is influenced by the selection of prior distribution. Jeffreys’ prior distribution is a kind of Non-informative prior distribution. This prior is used when the information about parameter not available. Non-informative Jeffreys’ prior distribution is combined with the sample information resulting the posterior distribution. Posterior distribution is used to estimate the parameter. The purposes of this research is to estimate the parameters of multivariate regression model using Bayesian method with Non-informative Jeffreys’ prior distribution. Based on the results and discussion, parameter estimation of β and Σ which were obtained from expected value of random variable of marginal posterior distribution function. The marginal posterior distributions for β and Σ are multivariate normal and inverse Wishart. However, in calculation of the expected value involving integral of a function which difficult to determine the value. Therefore, approach is needed by generating of random samples according to the posterior distribution characteristics of each parameter using Markov chain Monte Carlo (MCMC) Gibbs sampling algorithm.

Transfer functions in collection scanning near-field optical microscopy

DEFF Research Database (Denmark)

Bozhevolnyi, Sergey I.; Vohnsen, Brian; Bozhevolnaya, Elena A.

1999-01-01

are considered with respect to the relation between near-field optical images and the corresponding intensity distributions. Our conclusions are supported with numerical simulations and experimental results obtained by using a photon scanning tunneling microscope with an uncoated fiber tip....

A Semi-Discrete Landweber-Kaczmarz Method for Cone Beam Tomography and Laminography Exploiting Geometric Prior Information

Science.gov (United States)

Vogelgesang, Jonas; Schorr, Christian

2016-12-01

We present a semi-discrete Landweber-Kaczmarz method for solving linear ill-posed problems and its application to Cone Beam tomography and laminography. Using a basis function-type discretization in the image domain, we derive a semi-discrete model of the underlying scanning system. Based on this model, the proposed method provides an approximate solution of the reconstruction problem, i.e. reconstructing the density function of a given object from its projections, in suitable subspaces equipped with basis function-dependent weights. This approach intuitively allows the incorporation of additional information about the inspected object leading to a more accurate model of the X-rays through the object. Also, physical conditions of the scanning geometry, like flat detectors in computerized tomography as used in non-destructive testing applications as well as non-regular scanning curves e.g. appearing in computed laminography (CL) applications, are directly taken into account during the modeling process. Finally, numerical experiments of a typical CL application in three dimensions are provided to verify the proposed method. The introduction of geometric prior information leads to a significantly increased image quality and superior reconstructions compared to standard iterative methods.

Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.

Science.gov (United States)

Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki

2013-07-29

We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.

Analytical scanning evanescent microwave microscope and control stage

Science.gov (United States)

Xiang, Xiao-Dong; Gao, Chen; Duewer, Fred; Yang, Hai Tao; Lu, Yalin

2009-06-23

A scanning evanescent microwave microscope (SEMM) that uses near-field evanescent electromagnetic waves to probe sample properties is disclosed. The SEMM is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The SEMM has the ability to map dielectric constant, loss tangent, conductivity, electrical impedance, and other electrical parameters of materials. Such properties are then used to provide distance control over a wide range, from to microns to nanometers, over dielectric and conductive samples for a scanned evanescent microwave probe, which enable quantitative non-contact and submicron spatial resolution topographic and electrical impedance profiling of dielectric, nonlinear dielectric and conductive materials. The invention also allows quantitative estimation of microwave impedance using signals obtained by the scanned evanescent microwave probe and quasistatic approximation modeling. The SEMM can be used to measure electrical properties of both dielectric and electrically conducting materials.

Iterated random walks with shape prior

DEFF Research Database (Denmark)

Pujadas, Esmeralda Ruiz; Kjer, Hans Martin; Piella, Gemma

2016-01-01

the parametric probability density function. Then, random walks is performed iteratively aligning the prior with the current segmentation in every iteration. We tested the proposed approach with natural and medical images and compared it with the latest techniques with random walks and shape priors......We propose a new framework for image segmentation using random walks where a distance shape prior is combined with a region term. The shape prior is weighted by a confidence map to reduce the influence of the prior in high gradient areas and the region term is computed with k-means to estimate....... The experiments suggest that this method gives promising results for medical and natural images....

Gastrointestinal scanning agent

International Nuclear Information System (INIS)

Francis, M.D.

1980-01-01

An easily prepared radiolabeled gastrointestinal scanning agent is described. Technetium-99m has ideal characteristics for imaging the upper and lower GI tract and determining stomach emptying and intestinal transit time when used with an insoluble particulate material. For example, crystalline and amorphous calcium phosphate particles can be effectively labeled in a one-step process using sup(99m)TcO 4 and SnCl 2 . These labeled particles have insignificant mass and when administered orally pass through the GI tract unchanged, without affecting the handling and density of the intestinal contents. Visualization of the esophageal entry into the stomach, the greater and lesser curvatures of the stomach, ejection into the duodenum, and rates of passage through the upper and lower GI tract are obtained. The slurry of sup(99m)TC particulate can be given rectally by enema. Good images of the cecum and the ascending, transverse, and descending colon are obtained. Mucosal folds and the splenic and hepatic flexures are visualized. The resilience of the large intestine is also readily visualized by pneumocolonographic techniques. (author)

Error analysis of motion correction method for laser scanning of moving objects

Science.gov (United States)

Goel, S.; Lohani, B.

2014-05-01

The limitation of conventional laser scanning methods is that the objects being scanned should be static. The need of scanning moving objects has resulted in the development of new methods capable of generating correct 3D geometry of moving objects. Limited literature is available showing development of very few methods capable of catering to the problem of object motion during scanning. All the existing methods utilize their own models or sensors. Any studies on error modelling or analysis of any of the motion correction methods are found to be lacking in literature. In this paper, we develop the error budget and present the analysis of one such `motion correction' method. This method assumes availability of position and orientation information of the moving object which in general can be obtained by installing a POS system on board or by use of some tracking devices. It then uses this information along with laser scanner data to apply correction to laser data, thus resulting in correct geometry despite the object being mobile during scanning. The major application of this method lie in the shipping industry to scan ships either moving or parked in the sea and to scan other objects like hot air balloons or aerostats. It is to be noted that the other methods of "motion correction" explained in literature can not be applied to scan the objects mentioned here making the chosen method quite unique. This paper presents some interesting insights in to the functioning of "motion correction" method as well as a detailed account of the behavior and variation of the error due to different sensor components alone and in combination with each other. The analysis can be used to obtain insights in to optimal utilization of available components for achieving the best results.

Bone scan and joint scan of hands and feet in rheumatoid arthritis

International Nuclear Information System (INIS)

Carpentier, N.; Verbeke, S.; Perdrisot, R.; Grilo, R.M.; Quenesson, E.; Bonnet, C.; Vergne, P.; Treves, R.; Bertin, P.; Boutros-Toni, F.

2000-01-01

The aim of this study was to determine the ability of joint scan and bone scan of hands and feet, in patients with rheumatoid arthritis, to localize the altered joints. The sensitivity, the specificity, the positive predictive value (PPV) and the negative predictive value (NPV) of joint scan were determined in comparison with clinical joint assessment. Fifteen patients (780 joints) were clinically examined (pain and synovitis); during the same day, a bone scan and a joint scan were realized by oxidronate 99m Tc intravenous injection. Patients were scanned 5 minutes (tissual time, T t ) and 3 hours 1/4 (bone time, T 0 ) after the administration. The uptake of the bi-phosphonate was evaluated with a qualitative method using a grey scale. The uptake of 99m Tc oxidronate was quantitated using an extra-articular region of interest. The sensitivity, specificity, PPV and NPV of the scan at Tt were 46%, 96%, 85% et 78%. The same parameters were 75%, 66%, 53% and 84% for the scan realized at T 0 . The joint scan has showed 22% of false positive. These false positives could be a consequence of an earlier detection of joint alterations by scan. The joint scan should forecast the evolution of joints in patients with rheumatoid arthritis. (author)

Scanning gamma camera

International Nuclear Information System (INIS)

Engdahl, L.W.; Batter, J.F. Jr.; Stout, K.J.

1977-01-01

A scanning system for a gamma camera providing for the overlapping of adjacent scan paths is described. A collimator mask having tapered edges provides for a graduated reduction in intensity of radiation received by a detector thereof, the reduction in intensity being graduated in a direction normal to the scanning path to provide a blending of images of adjacent scan paths. 31 claims, 15 figures

The Prior-project

DEFF Research Database (Denmark)

Engerer, Volkmar Paul; Roued-Cunliffe, Henriette; Albretsen, Jørgen

digitisation of Arthur Prior’s Nachlass kept in the Bodleian Library, Oxford. The DH infrastructure in question is the Prior Virtual Lab (PVL). PVL was established in 2011 in order to provide researchers in the field of temporal logic easy access to the papers of Arthur Norman Prior (1914-1969), and officially......In this paper, we present a DH research infrastructure which relies heavily on a combination of domain knowledge with information technology. The general goal is to develop tools to aid scholars in their interpretations and understanding of temporal logic. This in turn is based on an extensive...

Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

Science.gov (United States)

Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

2016-01-01

In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

Imaging properties and its improvements of scanning/imaging x-ray microscope

International Nuclear Information System (INIS)

Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

2016-01-01

A scanning / imaging X-ray microscope (SIXM) system has been developed at SPring-8. The SIXM consists of a scanning X-ray microscope with a one-dimensional (1D) X-ray focusing device and an imaging (full-field) X-ray microscope with a 1D X-ray objective. The motivation of the SIXM system is to realize a quantitative and highly-sensitive multimodal 3D X-ray tomography by taking advantages of both the scanning X-ray microscope using multi-pixel detector and the imaging X-ray microscope. Data acquisition process of a 2D image is completely different between in the horizontal direction and in the vertical direction; a 1D signal is obtained with the linear-scanning while the other dimensional signal is obtained with the imaging optics. Such condition have caused a serious problem on the imaging properties that the imaging quality in the vertical direction has been much worse than that in the horizontal direction. In this paper, two approaches to solve this problem will be presented. One is introducing a Fourier transform method for phase retrieval from one phase derivative image, and the other to develop and employ a 1D diffuser to produce an asymmetrical coherent illumination

Abdominal multi-organ CT segmentation using organ correlation graph and prediction-based shape and location priors.

Science.gov (United States)

Okada, Toshiyuki; Linguraru, Marius George; Hori, Masatoshi; Summers, Ronald M; Tomiyama, Noriyuki; Sato, Yoshinobu

2013-01-01

The paper addresses the automated segmentation of multiple organs in upper abdominal CT data. We propose a framework of multi-organ segmentation which is adaptable to any imaging conditions without using intensity information in manually traced training data. The features of the framework are as follows: (1) the organ correlation graph (OCG) is introduced, which encodes the spatial correlations among organs inherent in human anatomy; (2) the patient-specific organ shape and location priors obtained using OCG enable the estimation of intensity priors from only target data and optionally a number of untraced CT data of the same imaging condition as the target data. The proposed methods were evaluated through segmentation of eight abdominal organs (liver, spleen, left and right kidney, pancreas, gallbladder, aorta, and inferior vena cava) from 86 CT data obtained by four imaging conditions at two hospitals. The performance was comparable to the state-of-the-art method using intensity priors constructed from manually traced data.

Research on defect detection from incomplete scanning of X-ray

International Nuclear Information System (INIS)

Zhang Shunli; Zhang Dinghua; Cheng Yunyong; Li Xiaolin

2011-01-01

Computed tomography (CT) is an advanced means of non-destructive testing, which has been widely used in medical and industrial fields. Aiming at the non-destructive testing problem of large industrial components, It presents a defect detection method from incomplete scanning of X-ray. Firstly, a set of incomplete scanning projection data before using the component has been obtained, then reconstruct them by algebraic re- construction technique (ART), and take the reconstructed images as the norm images. Then, the incomplete projection data of different times during the use of the component has been obtained, and reconstruct them by ART algorithm. Finally, It makes digital subtraction operation by the reconstructed images and the norm images, the defection can be detected clearly and intuitively from the subtraction image. Experimental result shows the proposed method is effective. (authors)

Flash Glucose Monitoring: Differences Between Intermittently Scanned and Continuously Stored Data.

Science.gov (United States)

Pleus, Stefan; Kamecke, Ulrike; Link, Manuela; Haug, Cornelia; Freckmann, Guido

2018-03-01

The flash glucose monitoring system FreeStyle Libre (Abbott Diabetes Care Ltd., Witney, UK) measures interstitial glucose concentrations and continuously stores measurement values every 15 minutes. To obtain a current glucose reading, users have to scan the sensor with the reader. In a clinical trial, 5% of the scanned data showed relative differences of more than ±10% compared with continuously stored data points (median -0.5%). Such differences might impact results of studies using this system. It should be indicated whether scanned or continuously stored data were used for analyses. Health care professionals might have to differentiate between data reports from clinical software and the scanned data their patients are provided with. Additional information on these differences and their potential impact on therapeutic decisions would be helpful.

Scanning tunneling microscopy II further applications and related scanning techniques

CERN Document Server

Güntherodt, Hans-Joachim

1992-01-01

Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in Vol. I, these sudies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described inchapters on scanning force microscopy, magnetic force microscopy, scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Togehter, the two volumes give a comprehensive account of experimental aspcets of STM. They provide essentialreading and reference material for all students and researchers involvedin this field.

Bayesian Analysis of two Censored Shifted Gompertz Mixture Distributions using Informative and Noninformative Priors

Directory of Open Access Journals (Sweden)

Tabassum Naz Sindhu

2017-03-01

Full Text Available This study deals with Bayesian analysis of shifted Gompertz mixture model under type-I censored samples assuming both informative and noninformative priors. We have discussed the Bayesian estimation of parameters of shifted Gompertz mixture model under the uniform, and gamma priors assuming three loss functions. Further, some properties of the model with some graphs of the mixture density are discussed. These properties include Bayes estimators, posterior risks and reliability function under simulation scheme. Bayes estimates are obtained considering two cases: (a when the shape parameter is known and (b when all parameters are unknown. We analyzed some simulated sets in order to investigate the effect of prior belief, loss functions, and performance of the proposed set of estimators of the mixture model parameters.

A laser sheet self-calibration method for scanning PIV

Science.gov (United States)

Knutsen, Anna N.; Lawson, John M.; Dawson, James R.; Worth, Nicholas A.

2017-10-01

Knowledge of laser sheet position, orientation, and thickness is a fundamental requirement of scanning PIV and other laser-scanning methods. This paper describes the development and evaluation of a new laser sheet self-calibration method for stereoscopic scanning PIV, which allows the measurement of these properties from particle images themselves. The approach is to fit a laser sheet model by treating particles as randomly distributed probes of the laser sheet profile, whose position is obtained via a triangulation procedure enhanced by matching particle images according to their variation in brightness over a scan. Numerical simulations and tests with experimental data were used to quantify the sensitivity of the method to typical experimental error sources and validate its performance in practice. The numerical simulations demonstrate the accurate recovery of the laser sheet parameters over range of different seeding densities and sheet thicknesses. Furthermore, they show that the method is robust to significant image noise and camera misalignment. Tests with experimental data confirm that the laser sheet model can be accurately reconstructed with no impairment to PIV measurement accuracy. The new method is more efficient and robust in comparison with the standard (self-) calibration approach, which requires an involved, separate calibration step that is sensitive to experimental misalignments. The method significantly improves the practicality of making accurate scanning PIV measurements and broadens its potential applicability to scanning systems with significant vibrations.

CT Scan

Science.gov (United States)

... disease, lung nodules and liver masses Monitor the effectiveness of certain treatments, such as cancer treatment Detect ... scan done in a hospital or an outpatient facility. CT scans are painless and, with newer machines, ...

Renal scan

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/003790.htm Renal scan To use the sharing features on this ... anaphylaxis . Alternative Names Renogram; Kidney scan Images Kidney anatomy Kidney - blood and urine flow References Chernecky CC, ...

Precursor and Neutral Loss Scans in an RF Scanning Linear Quadrupole Ion Trap

Science.gov (United States)

Snyder, Dalton T.; Szalwinski, Lucas J.; Schrader, Robert L.; Pirro, Valentina; Hilger, Ryan; Cooks, R. Graham

2018-03-01

Methodology for performing precursor and neutral loss scans in an RF scanning linear quadrupole ion trap is described and compared to the unconventional ac frequency scan technique. In the RF scanning variant, precursor ions are mass selectively excited by a fixed frequency resonance excitation signal at low Mathieu q while the RF amplitude is ramped linearly to pass ions through the point of excitation such that the excited ion's m/z varies linearly with time. Ironically, a nonlinear ac frequency scan is still required for ejection of the product ions since their frequencies vary nonlinearly with the linearly varying RF amplitude. In the case of the precursor scan, the ejection frequency must be scanned so that it is fixed on a product ion m/z throughout the RF scan, whereas in the neutral loss scan, it must be scanned to maintain a constant mass offset from the excited precursor ions. Both simultaneous and sequential permutation scans are possible; only the former are demonstrated here. The scans described are performed on a variety of samples using different ionization sources: protonated amphetamine ions generated by nanoelectrospray ionization (nESI), explosives ionized by low-temperature plasma (LTP), and chemical warfare agent simulants sampled from a surface and analyzed with swab touch spray (TS). We lastly conclude that the ac frequency scan variant of these MS/MS scans is preferred due to electronic simplicity. In an accompanying manuscript, we thus describe the implementation of orthogonal double resonance precursor and neutral loss scans on the Mini 12 using constant RF voltage. [Figure not available: see fulltext.

Bayesian inference from count data using discrete uniform priors.

Directory of Open Access Journals (Sweden)

Federico Comoglio

Full Text Available We consider a set of sample counts obtained by sampling arbitrary fractions of a finite volume containing an homogeneously dispersed population of identical objects. We report a Bayesian derivation of the posterior probability distribution of the population size using a binomial likelihood and non-conjugate, discrete uniform priors under sampling with or without replacement. Our derivation yields a computationally feasible formula that can prove useful in a variety of statistical problems involving absolute quantification under uncertainty. We implemented our algorithm in the R package dupiR and compared it with a previously proposed Bayesian method based on a Gamma prior. As a showcase, we demonstrate that our inference framework can be used to estimate bacterial survival curves from measurements characterized by extremely low or zero counts and rather high sampling fractions. All in all, we provide a versatile, general purpose algorithm to infer population sizes from count data, which can find application in a broad spectrum of biological and physical problems.

A fluorescent screen + CCD system for quality assurance of therapeutic scanned ion beams

Energy Technology Data Exchange (ETDEWEB)

Takeshita, E., E-mail: eriuli@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan); Furukawa, T., E-mail: t_furu@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan); Inaniwa, T., E-mail: taku@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan); Sato, S., E-mail: shin_s@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan); Himukai, T., E-mail: himukai@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan); Shirai, T., E-mail: t_shirai@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan); Noda, K., E-mail: noda_k@nirs.go.jp [National Institute of Radiological Sciences, Chiba (Japan)

2011-12-15

A fluorescent screen + a charge coupled device (CCD) system were developed to verify the performance of scanned ion beams at the HIMAC. The fluorescent light from the screen is observed by the CCD camera. Two-dimensional fields, produced by the scanning process, i.e., the position and the size of the beam for each scan, represent of the important issues in scanning irradiation. In the developed system, the two-dimensional relative fluence and the flatness of the irradiation field were measured in a straightforward technique from the luminance distribution on the screen. The position and the size of the beams were obtained from centroid computation results of the brightness. By the good sensitivity and spatial resolution of the fluorescent screen + CCD system, the scanned ion beams were verified as the measurements at the HIMAC prototype scanning system.

A fluorescent screen + CCD system for quality assurance of therapeutic scanned ion beams

Science.gov (United States)

Takeshita, E.; Furukawa, T.; Inaniwa, T.; Sato, S.; Himukai, T.; Shirai, T.; Noda, K.

2011-12-01

A fluorescent screen + a charge coupled device (CCD) system were developed to verify the performance of scanned ion beams at the HIMAC. The fluorescent light from the screen is observed by the CCD camera. Two-dimensional fields, produced by the scanning process, i.e., the position and the size of the beam for each scan, represent of the important issues in scanning irradiation. In the developed system, the two-dimensional relative fluence and the flatness of the irradiation field were measured in a straightforward technique from the luminance distribution on the screen. The position and the size of the beams were obtained from centroid computation results of the brightness. By the good sensitivity and spatial resolution of the fluorescent screen + CCD system, the scanned ion beams were verified as the measurements at the HIMAC prototype scanning system.

Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

Science.gov (United States)

Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai; Kalinin, Sergei V.; Jesse, Stephen; Unocic, Raymond R.

2017-03-01

Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.

Small nodule detectability evaluation using a generalized scan-statistic model

International Nuclear Information System (INIS)

Popescu, Lucretiu M; Lewitt, Robert M

2006-01-01

In this paper is investigated the use of the scan statistic for evaluating the detectability of small nodules in medical images. The scan-statistic method is often used in applications in which random fields must be searched for abnormal local features. Several results of the detection with localization theory are reviewed and a generalization is presented using the noise nodule distribution obtained by scanning arbitrary areas. One benefit of the noise nodule model is that it enables determination of the scan-statistic distribution by using only a few image samples in a way suitable both for simulation and experimental setups. Also, based on the noise nodule model, the case of multiple targets per image is addressed and an image abnormality test using the likelihood ratio and an alternative test using multiple decision thresholds are derived. The results obtained reveal that in the case of low contrast nodules or multiple nodules the usual test strategy based on a single decision threshold underperforms compared with the alternative tests. That is a consequence of the fact that not only the contrast or the size, but also the number of suspicious nodules is a clue indicating the image abnormality. In the case of the likelihood ratio test, the multiple clues are unified in a single decision variable. Other tests that process multiple clues differently do not necessarily produce a unique ROC curve, as shown in examples using a test involving two decision thresholds. We present examples with two-dimensional time-of-flight (TOF) and non-TOF PET image sets analysed using the scan statistic for different search areas, as well as the fixed position observer

Usefulness of thin slice target CT scan in detecting mediastinal and hilar lymphadenopathy

International Nuclear Information System (INIS)

Yoshida, Shoji; Maeda, Tomoho; Nishioka, Masatoshi

1986-01-01

Comparative study of target scan with the different slice thickness and scan modes was performed to evaluate the mediastinal and hilar lymphadenopathy. 20 cases in controls and 35 cases in lymphadenopathy were examined. To delineate mediastinal and hilar lymphadenopathy, the scan mode of standard target was most useful in contrast and sharpness. Thin slice thickness with 5 mm was necessary in detecting small lymphnode or contour and internal structure of enlarged lymphnode. Valuable estimation of 5 mm contiguous target scan was obtained in the subaortic node (no. 5), tracheobronchial node (no. 4), precarinal and subcarinal node (no. 7) and right hilar node (no. 12). (author)

Fluorescence image excited by a scanning UV-LED light

Science.gov (United States)

Tsai, Hsin-Yi; Chen, Yi-Ju; Huang, Kuo-Cheng

2013-03-01

An optical scanning system using UV-LED light to induced fluorescence technology can enhance a fluorescence image significantly in a short period. It has several advantages such as lower power consumption, no scattering effect in skins, and multilayer images can be obtained to analyze skin disease. From the experiment results, the light intensity increases with increase spot size and decrease scanning speed, but the image resolution is oppositely. Moreover, the system could be widely used in clinical diagnosis and photodynamic therapy for skin disease because even the irradiated time of fluorescence substance is short but it will provide accurately positioning of fluorescence object.

Observer agreement in the diagnosis of interstitial lung diseases based on HRCT scans

International Nuclear Information System (INIS)

Antunes, Viviane Baptista; Meirelles, Gustavo de Souza Portes; Jasinowodolinski, Dany; Verrastro, Carlos Gustavo Yuji; Torlai, Fabiola Goda

2010-01-01

Objective: to determine the interobserver and intraobserver agreement in the diagnosis of interstitial lung diseases (ILDs) based on HRCT scans and the impact of observer expertise, clinical data and confidence level on such agreement. Methods: two thoracic radiologists and two general radiologists independently reviewed the HRCT images of 58 patients with ILDs on two distinct occasions: prior to and after the clinical anamnesis. The radiologists selected up to three diagnostic hypotheses for each patient and defined the confidence level for these hypotheses. One of the thoracic and one of the general radiologists re-evaluated the same images up to three months after the first readings. In the coefficient analyses, the kappa statistic was used. Results: the thoracic and general radiologists, respectively, agreed on at least one diagnosis for each patient in 91.4% and 82.8% of the patients. The thoracic radiologists agreed on the most likely diagnosis in 48.3% (κ = 0.42) and 62.1% (κ = 0.58) of the cases, respectively, prior to and after the clinical anamnesis; likewise, the general radiologists agreed on the most likely diagnosis in 37.9% (κ 0.32) and 36.2% (κ = 0.30) of the cases. For the thoracic radiologist, the intraobserver agreement on the most likely diagnosis was 0.73 and 0.63 prior to and after the clinical anamnesis, respectively. That for the general radiologist was 0.38 and 0.42.The thoracic radiologists presented almost perfect agreement for the diagnostic hypotheses defined with the high confidence level. Conclusions: Interobserver and intraobserver agreement in the diagnosis of ILDs based on HRCT scans ranged from fair to almost perfect and was influenced by radiologist expertise, clinical history and confidence level. (author)

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

Energy Technology Data Exchange (ETDEWEB)

Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rhodes, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schemer-Kohrn, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzman, Anthony D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-10-01

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

Energy Technology Data Exchange (ETDEWEB)

Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rhodes, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schemer-Kohrn, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzman, Anthony D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-03-30

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

The Influence of Prior Knowledge on the Retrieval-Directed Function of Note Taking in Prior Knowledge Activation

Science.gov (United States)

Wetzels, Sandra A. J.; Kester, Liesbeth; van Merrienboer, Jeroen J. G.; Broers, Nick J.

2011-01-01

Background: Prior knowledge activation facilitates learning. Note taking during prior knowledge activation (i.e., note taking directed at retrieving information from memory) might facilitate the activation process by enabling learners to build an external representation of their prior knowledge. However, taking notes might be less effective in…

Diagnostic leg scanning for deep venous thrombosis in the recently heparinized patient

International Nuclear Information System (INIS)

Mant, M.J.; O'Brien, B.D.; Russell, D.B.

1981-01-01

Leg scanning with fibrinogen 125I, either alone on in combination with other procedures, has been proposed as an alternative to venography for diagnosis of deep venous thrombi. Clinical circumstances may necessitate anticoagulation before scanning can be performed, which could alter its reliability. We have compared the results of scanning with venographic findings in heparinized patients with venous thromboembolism. Different criteria for an abnormal leg scan gave different sensitivities and specificities. During the first four days of scanning with a requirement for a persistently abnormal result, five of eight criteria had high specificity (greater than 92%). However, sensitivities did not exceed 55%. With the use of transiently abnormal results and six days of scanning, higher sensitivities were obtained but specificities were reduced. No criterion gave results considered acceptable for a diagnostic test for deep venous thrombosis. Leg scanning should therefore not be used for this purpose in patients who have received anticoagulants. Our results also suggest that duration of symptoms has little effect on the sensitivity of leg scanning and that the test is more reliable for establishing the presence of thrombus than at defining its location

Diagnostic value of sectional images obtained by emission tomography

International Nuclear Information System (INIS)

Roucayrol, J.C.

1981-01-01

It is now possible to obtain clear images of the various planes in and around a structure with ultra-sounds (echotomography), X-rays (computerized tomography) and recently, gamma-rays from radioactive substances (emission tomography). Axial transverse tomography, which is described here, is to conventional scintigraphy what CT scan is to radiography. It provides images of any structure capable of concentrating sufficiently a radioactive substance administered intravenously. These images are perpendicular to the longitudinal axis of the body. As shown by examples in the liver, lungs and myocardium, lesions which had passed unnoticed with other exploratory techniques can now be demonstrated, and the location, shape and extension of known lesions can be more accurately assessed. Emission tomography already has its place in modern diagnostic procedures side by side with echotomography and CT scan [fr

Does obtaining an initial magnetic resonance imaging decrease the reamputation rates in the diabetic foot?

Directory of Open Access Journals (Sweden)

Marlena Jbara

2016-06-01

Full Text Available Objective: Diabetes mellitus (DM through its over glycosylation of neurovascular structures and resultant peripheral neuropathy continues to be the major risk factor for pedal amputation. Repetitive trauma to the insensate foot results in diabetic foot ulcers, which are at high risk to develop osteomyelitis. Many patients who present with diabetic foot complications will undergo one or more pedal amputations during the course of their disease. The purpose of this study was to determine if obtaining an initial magnetic resonance imaging (MRI, prior to the first amputation, is associated with a decreased rate of reamputation in the diabetic foot. Our hypothesis was that the rate of reamputation may be associated with underutilization of obtaining an initial MRI, useful in presurgical planning. This study was designed to determine whether there was an association between the reamputation rate in diabetic patients and utilization of MRI in the presurgical planning and prior to initial forefoot amputations. Methods: Following approval by our institutional review board, our study design consisted of a retrospective cohort analysis of 413 patients at Staten Island University Hospital, a 700-bed tertiary referral center between 2008 and 2013 who underwent an initial great toe (hallux amputation. Of the 413 patients with a hallux amputation, there were 368 eligible patients who had a history of DM with documented hemoglobin A1c (HbA1c within 3 months of the initial first ray (hallux and first metatarsal amputation and available radiographic data. Statistical analysis compared the incidence rates of reamputation between patients who underwent initial MRI and those who did not obtain an initial MRI prior to their first amputation. The reamputation rate was compared after adjustment for age, gender, ethnicity, HbA1c, cardiovascular disease, hypoalbuminemia, smoking, body mass index, and prior antibiotic treatment. Results: The results of our statistical

Fluorescent scanning x-ray tomography with synchrotron radiation

Science.gov (United States)

Takeda, Tohoru; Maeda, Toshikazu; Yuasa, Tetsuya; Akatsuka, Takao; Ito, Tatsuo; Kishi, Kenichi; Wu, Jin; Kazama, Masahiro; Hyodo, Kazuyuki; Itai, Yuji

1995-02-01

Fluorescent scanning (FS) x-ray tomography was developed to detect nonradioactive tracer materials (iodine and gadolinium) in a living object. FS x-ray tomography consists of a silicon (111) channel cut monochromator, an x-ray shutter, an x-ray slit system and a collimator for detection, a scanning table for the target organ, and an x-ray detector with pure germanium. The minimal detectable dose of iodine in this experiment was 100 ng in a volume of 2 mm3 and a linear relationship was shown between the photon counts of a fluorescent x ray and the concentration of iodine contrast material. A FS x-ray tomographic image was clearly obtained with a phantom.

Varying prior information in Bayesian inversion

International Nuclear Information System (INIS)

Walker, Matthew; Curtis, Andrew

2014-01-01

Bayes' rule is used to combine likelihood and prior probability distributions. The former represents knowledge derived from new data, the latter represents pre-existing knowledge; the Bayesian combination is the so-called posterior distribution, representing the resultant new state of knowledge. While varying the likelihood due to differing data observations is common, there are also situations where the prior distribution must be changed or replaced repeatedly. For example, in mixture density neural network (MDN) inversion, using current methods the neural network employed for inversion needs to be retrained every time prior information changes. We develop a method of prior replacement to vary the prior without re-training the network. Thus the efficiency of MDN inversions can be increased, typically by orders of magnitude when applied to geophysical problems. We demonstrate this for the inversion of seismic attributes in a synthetic subsurface geological reservoir model. We also present results which suggest that prior replacement can be used to control the statistical properties (such as variance) of the final estimate of the posterior in more general (e.g., Monte Carlo based) inverse problem solutions. (paper)

Column gamma-ray scanning of the 'Hector Molina' Distillery

International Nuclear Information System (INIS)

Derivet Zarzabal, M.; Capote Ferrera, E.; Fernandez Gomez, I.; Carrazana Gonzalez, L.; Borroto Portela, J.

2015-01-01

Gamma-ray scanning, often referred to as 'column scanning', is a convenient, cost effective, fast, efficient and non-invasive technique to examine internal characteristics of a certain equipment, like alcohol distillation columns, while it is in operation. Column scanning allows to engineers, to study hydraulics tray inside of distillation column in on-line condition. It provides essential data to optimize the performance of columns, extend column run times, to evaluate effects of defective track and to identify maintenance requirements. This knowledge can reduce repair times significantly. In the year 2014, the Environmental Radiological Surveillance Laboratory from Center of Radiation Protection and Hygiene, introduced this service in the 'Hector Molina' Distillery. The diagnosis carried out allowed the detection of some anomalies in its operation. In this work the results obtained during gamma-ray scanning of the column are shown. (Author)

Lung scan alterations in congenital heart disease

Energy Technology Data Exchange (ETDEWEB)

Dietrich, R; Sanchez, J; Munoz, A; Lanaro, A E; Pico, A M

1975-04-01

This report analyzes the patterns in 54 lung scannings of 34 patients with altered pulmonary blood flow due to congenital heart disease. The technique and the results are presented. According to the images obtained, the patients are classified in three groups: Group I--normal distribution with more concentration of particles over the right lung and the bases. Group II--normal scannings found in left to right shunts unless there is pulmonary venous hypertension in which case the apex-base relationship was inverted. Group III--patients with right to left shunts of different types presenting various patterns according to severity, associated anomalies and palliative surgery. The hemodynamics created by cardiac defects and surgical procedures explain these alterations. This method is recommended in view of its advantages and accurate results.

Scanning and georeferencing historical USGS quadrangles

Science.gov (United States)

Fishburn, Kristin A.; Davis, Larry R.; Allord, Gregory J.

2017-06-23

The U.S. Geological Survey (USGS) National Geospatial Program is scanning published USGS 1:250,000-scale and larger topographic maps printed between 1884, the inception of the topographic mapping program, and 2006. The goal of this project, which began publishing the Historical Topographic Map Collection in 2011, is to provide access to a digital repository of USGS topographic maps that is available to the public at no cost. For more than 125 years, USGS topographic maps have accurately portrayed the complex geography of the Nation. The USGS is the Nation’s largest producer of traditional topographic maps, and, prior to 2006, USGS topographic maps were created using traditional cartographic methods and printed using a lithographic process. The next generation of topographic maps, US Topo, is being released by the USGS in digital form, and newer technologies make it possible to also deliver historical maps in the same electronic format that is more publicly accessible.

2D biological representations with reduced speckle obtained from two perpendicular ultrasonic arrays.

Science.gov (United States)

Rodriguez-Hernandez, Miguel A; Gomez-Sacristan, Angel; Sempere-Payá, Víctor M

2016-04-29

Ultrasound diagnosis is a widely used medical tool. Among the various ultrasound techniques, ultrasonic imaging is particularly relevant. This paper presents an improvement to a two-dimensional (2D) ultrasonic system using measurements taken from perpendicular planes, where digital signal processing techniques are used to combine one-dimensional (1D) A-scans were acquired by individual transducers in arrays located in perpendicular planes. An algorithm used to combine measurements is improved based on the wavelet transform, which includes a denoising step during the 2D representation generation process. The inclusion of this new denoising stage generates higher quality 2D representations with a reduced level of speckling. The paper includes different 2D representations obtained from noisy A-scans and compares the improvements obtained by including the denoising stage.

Resection of parathyroid tumor in the aorticopulmonary window without prior neck exploration

International Nuclear Information System (INIS)

McHenry, C.; Walsh, M.; Jarosz, H.; Henkin, R.; Tope, J.; Lawrence, A.M.; Paloyan, E.

1988-01-01

Of 522 patients with hyperparathyroidism operated on from 1973 to 1987 at our institution, there were seven (1.3%), each with an ectopic, hyperfunctioning mediastinal parathyroid adenoma, who required median sternotomy. In three of these seven patients, the tumor was located in the aorticopulmonary window. A 61-year-old woman with primary hyperparathyroidism had a preoperative thallium-technetium subtraction scan that showed thallium uptake at the base of the heart without any uptake in the neck. After further workup and without prior neck exploration, a parathyroid adenoma was found in the aorticopulmonary window through a median sternotomy. Six months later, serum calcium, phosphorus, and parathyroid hormone values remain normal. Two other cases of parathyroid adenoma in the aorticopulmonary window are presented. Of these two patients, the thallium scan was a key element in the immediate mediastinal exploration of one, who was transferred from another hospital comatose and intubated, in acute hypercalcemic crisis. Since mediastinal parathyroid tumors that necessitate median sternotomy occur in less than 2% of patients with primary hyperparathyroidism, we do not advocate routine preoperative localization studies before an initial cervical operation; localization, however, may be justified in selected cases, such as in critically ill patients or in instances of acute hyperparathyroidism, when the first operation needs to be curative

The Prior Internet Resources 2017

DEFF Research Database (Denmark)

Engerer, Volkmar Paul; Albretsen, Jørgen

2017-01-01

The Prior Internet Resources (PIR) are presented. Prior’s unpublished scientific manuscripts and his wast letter correspondence with fellow researchers at the time, his Nachlass, is now subject to transcription by Prior-researchers worldwide, and form an integral part of PIR. It is demonstrated...

Pre- and postoperative ventilation-perfusion scan findings in patients undergoing total hip replacement or knee arthroplasty

International Nuclear Information System (INIS)

Kim, S.M.; Park, C.H.; Intenzo, C.M.

1988-01-01

Venous thrombolembolism is one of the major postoperative complications in patients undergoing total hip replacement (THR) or knee anthroplasty (TKA). The reported incidence of pulmonary embolism in this group is as high as 20%. The purpose of this report was to evaluate the value of preoperative and 7th-day postpoperative ventilation-perfusion (V/Q) lung scans in the management of patients undergoing elective reconstructive surgery of the hips or knees. Routine preoperative and 7th-day postoperative V/Q lung scans were obtained in 34 patients who underwent THR (17 patients) or TKA (17 patients). There were 15 male and 19 female patients, with an age distribution ranging from 56 to 80 years. Chest radiographs were obtained within 1 day of the pre- or postoperative lungs scan. Lung scans were interpreted by two experienced nuclear physicians

Penalised Complexity Priors for Stationary Autoregressive Processes

KAUST Repository

Sø rbye, Sigrunn Holbek; Rue, Haavard

2017-01-01

The autoregressive (AR) process of order p(AR(p)) is a central model in time series analysis. A Bayesian approach requires the user to define a prior distribution for the coefficients of the AR(p) model. Although it is easy to write down some prior, it is not at all obvious how to understand and interpret the prior distribution, to ensure that it behaves according to the users' prior knowledge. In this article, we approach this problem using the recently developed ideas of penalised complexity (PC) priors. These prior have important properties like robustness and invariance to reparameterisations, as well as a clear interpretation. A PC prior is computed based on specific principles, where model component complexity is penalised in terms of deviation from simple base model formulations. In the AR(1) case, we discuss two natural base model choices, corresponding to either independence in time or no change in time. The latter case is illustrated in a survival model with possible time-dependent frailty. For higher-order processes, we propose a sequential approach, where the base model for AR(p) is the corresponding AR(p-1) model expressed using the partial autocorrelations. The properties of the new prior distribution are compared with the reference prior in a simulation study.

Penalised Complexity Priors for Stationary Autoregressive Processes

KAUST Repository

Sørbye, Sigrunn Holbek

2017-05-25

The autoregressive (AR) process of order p(AR(p)) is a central model in time series analysis. A Bayesian approach requires the user to define a prior distribution for the coefficients of the AR(p) model. Although it is easy to write down some prior, it is not at all obvious how to understand and interpret the prior distribution, to ensure that it behaves according to the users\\' prior knowledge. In this article, we approach this problem using the recently developed ideas of penalised complexity (PC) priors. These prior have important properties like robustness and invariance to reparameterisations, as well as a clear interpretation. A PC prior is computed based on specific principles, where model component complexity is penalised in terms of deviation from simple base model formulations. In the AR(1) case, we discuss two natural base model choices, corresponding to either independence in time or no change in time. The latter case is illustrated in a survival model with possible time-dependent frailty. For higher-order processes, we propose a sequential approach, where the base model for AR(p) is the corresponding AR(p-1) model expressed using the partial autocorrelations. The properties of the new prior distribution are compared with the reference prior in a simulation study.

Correlation of (99m) Tc-DPD SPECT/CT Scan Findings and Diagnostic Blockades of Lumbar Medial Branches in Patients with Unspecific Low Back Pain in a Randomized-Controlled Trial.

Science.gov (United States)

Freiermuth, David; Kretzschmar, Martin; Bilecen, Denis; Schaeren, Stefan; Jacob, Augustinus Ludwig; Aeschbach, Armin; Ruppen, Wilhelm

2015-10-01

Zygapophyseal joints are the origin of pain in up to 30% of those with unspecific chronic low back pain. Until recently, no reliable clinical tests have been found to identify the patients who would benefit from denervation of the zygapophyseal joints by medial branch blockades. We performed a prospective randomized placebo-controlled trial to evaluate the value of high-resolution single-photon emission computed tomography (SPECT)/computed tomography (CT) of the lumbar spine prior to any diagnostic infiltration of the medial branches. Patients with suspected zygapophyseal joint-related pain were included in the study. After obtaining a SPECT/CT scan of the lumbar spine a set of infiltrations of the medial branches was done with local anesthetics and placebo on different days. Patients and anesthetists were blinded to the results of SPECT/CT and to the infiltrated agents. In a total of 29 study patients, 7 had positive and 22 negative infiltration tests, and 9 had positive and 20 negative SPECT/CT findings. Sensitivity of SPECT/CT for a positive response after diagnostic infiltration was 0.57 (95% confidence interval [CI] 0.18-0.90); specificity was 0.77 (CI 95% 0.55-0.92); odds ratio was 4.53 (CI 95% 0.75-27.40); and diagnostic accuracy was 0.72. Compared with diagnostic infiltrations SPECT/CT scans showed only a moderate sensitivity and specificity and, therefore, may not be recommended as a first line diagnostic tool prior to diagnostic infiltrations. Wiley Periodicals, Inc.

Implementation and evaluation of an ordered subsets reconstruction algorithm for transmission PET studies using median root prior and inter-update median filtering

International Nuclear Information System (INIS)

Bettinardi, V.; Gilardi, M.C.; Fazio, F.; Alenius, S.; Ruotsalainen, U.; Numminen, P.; Teraes, M.

2003-01-01

An ordered subsets (OS) reconstruction algorithm based on the median root prior (MRP) and inter-update median filtering was implemented for the reconstruction of low count statistics transmission (TR) scans. The OS-MRP-TR algorithm was evaluated using an experimental phantom, simulating positron emission tomography (PET) whole-body (WB) studies, as well as patient data. Various experimental conditions, in terms of TR scan time (from 1 h to 1 min), covering a wide range of TR count statistics were evaluated. The performance of the algorithm was assessed by comparing the mean value of the attenuation coefficient (MVAC) of known tissue types and the coefficient of variation (CV) for low-count TR images, reconstructed with the OS-MRP-TR algorithm, with reference values obtained from high-count TR images reconstructed with a filtered back-projection (FBP) algorithm. The reconstructed OS-MRP-TR images were then used for attenuation correction of the corresponding emission (EM) data. EM images reconstructed with attenuation correction generated by OS-MRP-TR images, of low count statistics, were compared with the EM images corrected for attenuation using reference (high statistics) TR data. In all the experimental situations considered, the OS-MRP-TR algorithm showed: (1) a tendency towards a stable solution in terms of MVAC; (2) a difference in the MVAC of within 5% for a TR scan of 1 min reconstructed with the OS-MRP-TR and a TR scan of 1 h reconstructed with the FBP algorithm; (3) effectiveness in noise reduction, particularly for low count statistics data [using a specific parameter configuration the TR images reconstructed with OS-MRP-TR(1 min) had a lower CV than the corresponding TR images of a 1-h scan reconstructed with the FBP algorithm]; (4) a difference of within 3% between the mean counts in the EM images attenuation corrected using the OS-MRP-TR images of 1 min and the mean counts in the EM images attenuation corrected using the OS-MRP-TR images of 1 h; (5

Scanning tunneling microscopy II further applications and related scanning techniques

CERN Document Server

Güntherodt, Hans-Joachim

1995-01-01

Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in STM I, these studies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described in chapters on scanning force microscopy, magnetic force microscopy, and scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Together, the two volumes give a comprehensive account of experimental aspects of STM. They provide essential reading and reference material for all students and researchers involved in this field. In this second edition the text has been updated and new methods are discussed.

Generalized Bayesian inference with sets of conjugate priors for dealing with prior-data conflict : course at Lund University

NARCIS (Netherlands)

Walter, G.

2015-01-01

In the Bayesian approach to statistical inference, possibly subjective knowledge on model parameters can be expressed by so-called prior distributions. A prior distribution is updated, via Bayes’ Rule, to the so-called posterior distribution, which combines prior information and information from

The Importance of Prior Knowledge.

Science.gov (United States)

Cleary, Linda Miller

1989-01-01

Recounts a college English teacher's experience of reading and rereading Noam Chomsky, building up a greater store of prior knowledge. Argues that Frank Smith provides a theory for the importance of prior knowledge and Chomsky's work provided a personal example with which to interpret and integrate that theory. (RS)

Some elaborating methods of gamma scanning results on irradiated nuclear fuels

International Nuclear Information System (INIS)

Sternini, E.

1979-01-01

Gamma scanning, as a post-irradiation examination, is a technique which provides a large number of informations on irradiated nuclear fuels. Power profile, fission products distribution, average and local burn-up of single elements structural and nuclear behaviour of fuel materials are examples of the obtained informations. In the present work experimental methods and theoretical calculations used at the CNEN hot cell laboratory for the mentioned purposes are described. Errors arising from the application of the gamma scanning technique are also discussed

Cooperative scans

NARCIS (Netherlands)

M. Zukowski (Marcin); P.A. Boncz (Peter); M.L. Kersten (Martin)

2004-01-01

textabstractData mining, information retrieval and other application areas exhibit a query load with multiple concurrent queries touching a large fraction of a relation. This leads to individual query plans based on a table scan or large index scan. The implementation of this access path in most

Performance analysis of three-dimensional ridge acquisition from live finger and palm surface scans

Science.gov (United States)

Fatehpuria, Abhishika; Lau, Daniel L.; Yalla, Veeraganesh; Hassebrook, Laurence G.

2007-04-01

Fingerprints are one of the most commonly used and relied-upon biometric technology. But often the captured fingerprint image is far from ideal due to imperfect acquisition techniques that can be slow and cumbersome to use without providing complete fingerprint information. Most of the diffculties arise due to the contact of the fingerprint surface with the sensor platen. To overcome these diffculties we have been developing a noncontact scanning system for acquiring a 3-D scan of a finger with suffciently high resolution which is then converted into a 2-D rolled equivalent image. In this paper, we describe certain quantitative measures evaluating scanner performance. Specifically, we use some image software components developed by the National Institute of Standards and Technology, to derive our performance metrics. Out of the eleven identified metrics, three were found to be most suitable for evaluating scanner performance. A comparison is also made between 2D fingerprint images obtained by the traditional means and the 2D images obtained after unrolling the 3D scans and the quality of the acquired scans is quantified using the metrics.

Incidental finding of knee osteoarthritis in bone scans performed in obese patients with neoplasia

International Nuclear Information System (INIS)

Regalado R, R.; Morales G, R.; Cano P, R.; Mendoza P, G.; Vidal N, L.

1996-01-01

Bone scanning performed in the Nuclear Medicine Center (IPEN-INEN) to patients with neoplastic diagnosis between January 1995 and June 1996, permitted the incidental finding of increased uptake images in the knees of 28 patients associated to an asymptomatic arthropathy: osteoarthritis. The histories and bone scanning of this patients were reviewed obtaining their weight, occupation, symptomatology, neoplastic diagnosis and previous scan diagnosis. Patients under 66 years old, asymptomatic, were included, not presenting secondary focuses, without arthropathia antecedent and with a body mass index equal or above class I. The arthropathy was classified according to the localization of the compromised compartment of the knee. >From the body mass index assessment of every patient it was obtained: Class I=12, Class II=11, Class III=3 and Class IV=1. The predominant localization of the osteoarthritic lesions was the patellar zone. We discuss factors that may influence the absence of symptoms of this disease, the relation obesity-osteoarthritis and the usefulness of bone scanning in the diagnosis of this arthropathy in these patients. (authors). 16 refs., 1 fig., 3 tabs

A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans.

Science.gov (United States)

Chen, Xu; Guo, Tengfei; Hou, Yubin; Zhang, Jing; Meng, Wenjie; Lu, Qingyou

2017-01-01

A new scan-head structure for the scanning tunneling microscope (STM) is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans) coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan). They are fixed at one end (called common end). A hollow tantalum shaft is coaxially housed in the XY -scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans

Directory of Open Access Journals (Sweden)

Xu Chen

2017-01-01

Full Text Available A new scan-head structure for the scanning tunneling microscope (STM is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan. They are fixed at one end (called common end. A hollow tantalum shaft is coaxially housed in the XY-scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

Special raster scanning for reduction of charging effects in scanning electron microscopy.

Science.gov (United States)

Suzuki, Kazuhiko; Oho, Eisaku

2014-01-01

A special raster scanning (SRS) method for reduction of charging effects is developed for the field of SEM. Both a conventional fast scan (horizontal direction) and an unusual scan (vertical direction) are adopted for acquiring raw data consisting of many sub-images. These data are converted to a proper SEM image using digital image processing techniques. About sharpness of the image and reduction of charging effects, the SRS is compared with the conventional fast scan (with frame-averaging) and the conventional slow scan. Experimental results show the effectiveness of SRS images. By a successful combination of the proposed scanning method and low accelerating voltage (LV)-SEMs, it is expected that higher-quality SEM images can be more easily acquired by the considerable reduction of charging effects, while maintaining the resolution. © 2013 Wiley Periodicals, Inc.

RANSAC approach for automated registration of terrestrial laser scans using linear features

Directory of Open Access Journals (Sweden)

K. Al-Durgham

2013-10-01

Full Text Available The registration process of terrestrial laser scans (TLS targets the problem of how to combine several laser scans in order to attain better information about features than what could be obtained through single scan. The main goal of the registration process is to estimate the parameters which determine geometrical variation between the origins of datasets collected from different locations. Scale, shifts, and rotation parameters are usually used to describe such variation. This paper presents a framework for the registration of overlapping terrestrial laser scans by establishing an automatic matching strategy that uses 3D linear features. More specifically, invariant separation characteristics between 3D linear features extracted from laser scans will be used to establish hypothesized conjugate linear features between the laser scans. These candidate matches are then used to geo-reference scans relative to a common reference frame. The registration workflow simulates the well-known RANndom Sample Consensus method (RANSAC for determining the registration parameters, whereas the iterative closest projected point (ICPP is utilized to determine the most probable solution of the transformation parameters from several solutions. The experimental results prove that the proposed methodology can be used for the automatic registration of terrestrial laser scans using linear features.

Direct CT scanning of the lesser pelvis - frontal vs sagittal plane

International Nuclear Information System (INIS)

Khadzhigeorgiev, G.; Lichev, A.

1994-01-01

Whenever axial scanning alone is used, the anatomical patterns of the true pelvis and the organs contained in it, particularly in women, give rise to diagnostic difficulties during CT assessment of neoplasms originating from these organs. The high demands on precision characterization of the pathological changes in the pelvis minor organs necessitate the obtaining of reliable density and size measurement data, not merely from the axial plane, but from the frontal and sagittal ones as well. The deficient information afforded by secondary reconstruction of the pelvis mind images requires an mandatory evaluation of the potentialities of direct frontal and direct sagittal scanning of the pelvis minor using standard CT equipment. Information yielded by images from direct frontal and direct sagittal pelvis minor scanning as well as diagnostic problems where application of this type of scanning is indicated operational difficulties and their overcoming, are among the issues discussed. 8 figs., 7 refs

The effect of Tc99m Sestamibi scans during acute chest pain on clinical management

International Nuclear Information System (INIS)

Baldey, A.; Cameron, P.; Grigg, L.; Knott, J.; Better, N.

1998-01-01

Full text: The aim of this study is to assess whether the increased sensitivity and specificity of Tc99m sestamibi scans, during acute chest pain, will lead to alteration in clinical management and potential cost saving in an Australian population. Consecutive patients who presented with acute chest pain were injected 800 MBq of Tc99m sestamibi during pain (Hot MlBI) and SPECT imaging performed 1-6 hours later. The population was those only with a 'intermediate risk' of myocardial ischaemia The patients included in patients, those in the Emergency Department, and those with a previous history of cardiac disease. 25% of patients required a second, pain free study the following day to differentiate acute ischaemia from prior infarction. A question sheet was filled out by the requesting physician prior to the study indicating the likelihood of cardiac disease and the proposed management if no 'Hot MIBI' scan was available. The treatment that the patient subsequently received was ascertained from the patient's medical record. Of the 28 patients, a prediction whether to or not to proceed to coronary angiography was made in 13 patients prior to the MIBI study being performed. Of the 13, 5 would have had coronary angiography performed. and in all 5, the decision to proceed to coronary angiography was averted by the 'Hot MIBI'. Of note, 3 patients were admitted purely because of an abnormal 'Hot MIBI'. The 'Hot MIBI' was able to reduce coronary care admissions by 83% reduce all admissions by 17%, and avert coronary angiography in 38% of patients. In this intermediate risk category patient, this translates to not only admissions saved but potential cost saving

Second-Harmonic Generation Scanning Microscopy on Domains in Al Surfaces

DEFF Research Database (Denmark)

Pedersen, Kjeld; Bozhevolnyi, Sergey I.

1999-01-01

Scanning optical second-harmonic generation microscopy has been used to investigate domains in the surface of polycrystaline Al. Strong contrast among the crystalline grains is obtained due to variations in their crystallographic orientations and thus also nonlinear response. The origin of the co...

Functional nanostructured titanium nitride films obtained by sputtering magnetron

International Nuclear Information System (INIS)

Sanchez, O.; Hernandez-Velez, M.; Navas, D.; Auger, M.A.; Baldonedo, J.L.; Sanz, R.; Pirota, K.R.; Vazquez, M.

2006-01-01

Development of new methods in the formation of hollow structures, in particular, nanotubes and nanocages are currently generating a great interest as a consequence of the growing relevance of these nanostructures on many technological fields, ranging from optoelectronics to biotechnology. In this work, we report the formation of titanium nitride (TiN) nanotubes and nanohills via reactive sputtering magnetron processes. Anodic Alumina Membranes (AAM) were used as template substrates to grow the TiN nanostructures. The AAM were obtained through electrochemical anodization processes by using oxalic acid solutions as electrolytes. The nanotubes were produced at temperatures below 100 deg. C, and using a pure titanium (99.995%) sputtering target and nitrogen as reactive gas. The obtained TiN thin films showed surface morphologies adjusted to pore diameter and interpore distance of the substrates, as well as ordered arrays of nanotubes or nanohills depending on the sputtering and template conditions. High Resolution Scanning Electron Microscopy (HRSEM) was used to elucidate both the surface order and morphology of the different grown nanostructures. The crystalline structure of the samples was examined using X-ray Diffraction (XRD) patterns and their qualitative chemical composition by using X-ray Energy Dispersive Spectroscopy (XEDS) in a scanning electron microscopy

Does aspiration of bones and joints affect results of later bone scanning

International Nuclear Information System (INIS)

Canale, S.T.; Harkness, R.M.; Thomas, P.A.; Massie, J.D.

1985-01-01

To determine the effect, if any, of needle aspiration on /sup 99m/Tc bone scanning, three different areas of 15 dogs were first aspirated and then imaged with technetium bone scintigraphy. The hip joint was aspirated, the distal femoral metaphysis was drilled and aspirated, and the tibial periosteum was scraped with an 18- or 20-gauge needle. Varying amounts of trauma were inflicted to simulate varying difficulties at aspiration. /sup 99m/Tc bone scans were obtained from 5 h to 10 days later. There was no evidence of focal technetium uptake after any hip joint aspiration. This was consistent regardless of the amount of trauma inflicted or the time from aspiration to bone scanning. Metaphyseal cortical drilling and tibial periosteal scraping occasionally caused some focal uptake when scanning was delayed greater than 2 days. When osteomyelitis or pyarthrosis is clinically suspected, joint aspiration can be performed without fear of producing a false- positive bone scan

Equilibrium blood pool scanning in the evaluation of hemophilic arthropathy

International Nuclear Information System (INIS)

Spies, S.; Green, D.; Rana, N.A.; Milgram, J.W.; Mintzer, R.

1978-01-01

Arthropathy was evaluated in six patients with severe hemophilia (factor VIII<1%) using the technique of blood pool scanning. Employing an in vivo method for erythrocyte labelling with technetium-99m, a dynamic perfusion sequence was obtained using a scintillation camera over the joint(s) to be examined. Subsequently, equilibrium blood pool images of the joints were obtained to determine regional blood volume. In young patients with repeated episodes of acute hemarthrosis, increased vascularity and increased blood pool in the affected joints were demonstrated. In older patients with fixed, contracted joints and degenerative arthropathy, vascularity and regional blood volume were not abnormal. Blood pool scanning is a safe, non-invasive technique that augments the clinical and radiographic examination of the joints. The method is helpful in distinguishing acute joint bleeding from chronic synovitis and arthritis, and may prove useful in selecting patients for synovectomy. (author)

Prior-knowledge Fitting of Accelerated Five-dimensional Echo Planar J-resolved Spectroscopic Imaging: Effect of Nonlinear Reconstruction on Quantitation.

Science.gov (United States)

Iqbal, Zohaib; Wilson, Neil E; Thomas, M Albert

2017-07-24

1 H Magnetic Resonance Spectroscopic imaging (SI) is a powerful tool capable of investigating metabolism in vivo from mul- tiple regions. However, SI techniques are time consuming, and are therefore difficult to implement clinically. By applying non-uniform sampling (NUS) and compressed sensing (CS) reconstruction, it is possible to accelerate these scans while re- taining key spectral information. One recently developed method that utilizes this type of acceleration is the five-dimensional echo planar J-resolved spectroscopic imaging (5D EP-JRESI) sequence, which is capable of obtaining two-dimensional (2D) spectra from three spatial dimensions. The prior-knowledge fitting (ProFit) algorithm is typically used to quantify 2D spectra in vivo, however the effects of NUS and CS reconstruction on the quantitation results are unknown. This study utilized a simulated brain phantom to investigate the errors introduced through the acceleration methods. Errors (normalized root mean square error >15%) were found between metabolite concentrations after twelve-fold acceleration for several low concentra- tion (OGM) human brain matter were quantified in vivo using the 5D EP-JRESI sequence with eight-fold acceleration.

Savings for visuomotor adaptation require prior history of error, not prior repetition of successful actions.

Science.gov (United States)

Leow, Li-Ann; de Rugy, Aymar; Marinovic, Welber; Riek, Stephan; Carroll, Timothy J

2016-10-01

When we move, perturbations to our body or the environment can elicit discrepancies between predicted and actual outcomes. We readily adapt movements to compensate for such discrepancies, and the retention of this learning is evident as savings, or faster readaptation to a previously encountered perturbation. The mechanistic processes contributing to savings, or even the necessary conditions for savings, are not fully understood. One theory suggests that savings requires increased sensitivity to previously experienced errors: when perturbations evoke a sequence of correlated errors, we increase our sensitivity to the errors experienced, which subsequently improves error correction (Herzfeld et al. 2014). An alternative theory suggests that a memory of actions is necessary for savings: when an action becomes associated with successful target acquisition through repetition, that action is more rapidly retrieved at subsequent learning (Huang et al. 2011). In the present study, to better understand the necessary conditions for savings, we tested how savings is affected by prior experience of similar errors and prior repetition of the action required to eliminate errors using a factorial design. Prior experience of errors induced by a visuomotor rotation in the savings block was either prevented at initial learning by gradually removing an oppositely signed perturbation or enforced by abruptly removing the perturbation. Prior repetition of the action required to eliminate errors in the savings block was either deprived or enforced by manipulating target location in preceding trials. The data suggest that prior experience of errors is both necessary and sufficient for savings, whereas prior repetition of a successful action is neither necessary nor sufficient for savings. Copyright © 2016 the American Physiological Society.

Factors Influencing Environmental Scanning in the Organizational Context

Directory of Open Access Journals (Sweden)

Zita Correia

2001-01-01

Full Text Available This paper identifies and analyses the factors internal to the organization, which affect the activity of environmental scanning, understood here as the information seeking activity of managers, directed at the company's external environment. These factors include individual factors, such as information consciousness and exposure to information, and organizational factors such as information climate and "outwardness". The main relationships among them are also analysed. These factors were identified in the course of research aiming to provide a comprehensive understanding of the environmental scanning process (Correia & Wilson, 1996. The methodology used - a case-study approach coupled with the grounded theory method of qualitative analysis - was of major importance in obtaining information that is grounded largely on the personal experience of managers.

Microstructural characterization of TiAl3 intermetallic obtained by the Fast solidification technique

International Nuclear Information System (INIS)

Angeles C, C.; Rosas, G.; Perez C, R.

1997-01-01

In this work preliminary studies about the TiAl 3 characterization are reported which is obtained starting from the Fast solidification technique in an arc furnace using Scanning electron microscopy, X-ray diffraction and Transmission electron microscopy. (Author)

Use on non-conjugate prior distributions in compound failure models. Final technical report

International Nuclear Information System (INIS)

Shultis, J.K.; Johnson, D.E.; Milliken, G.A.; Eckhoff, N.D.

1981-12-01

Several theoretical and computational techniques are presented for compound failure models in which the failure rate or failure probability for a class of components is considered to be a random variable. Both the failure-on-demand and failure-rate situation are considered. Ten different prior families are presented for describing the variation or uncertainty of the failure parameter. Methods considered for estimating values for the prior parameters from a given set of failure data are (1) matching data moments to those of the prior distribution, (2) matching data moments to those of the compound marginal distribution, and (3) the marginal maximum likelihood method. Numerical methods for computing the parameter estimators for all ten prior families are presented, as well as methods for obtaining estimates of the variances and covariance of the parameter estimators, it is shown that various confidence, probability, and tolerance intervals can be evaluated. Finally, to test the resulting failure models against the given failure data, generalized chi-squage and Kolmogorov-Smirnov goodness-of-fit tests are proposed together with a test to eliminate outliers from the failure data. Computer codes based on the results presented here have been prepared and are presented in a companion report

Clinical efficacy of FDG-PET scan in the patients with primary or recurrent gynecologic malignancies: clinical experiences with FDG-PET scan in cervical carcinoma of uterus

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Hoon

1998-12-01

This study was done to evaluate the clinical feasibility of FDG-PET scan in patients with cervical carcinoma. PET-scans were performed in 74 patients with cervical carcinoma from March, 1998 to September, 1998. Fourteen cases were done at pretreatment period and sixty cases were done at post-treatment follow up period. In this study, the scans were obtained after bladder emptying by foley catheter insertion and diuretics to reduce the tracer activity in the bladder and improve the images of central lesions. We could find some incidental recurrent or metastatic lesions by FDG-PET scan (at pretreatment; 5 cases, at post-treatment; clinically no evidence of disease; 8 cases). FDG-PET scan had high sensitivity (100%) for central lesions and metastatic lymph nodes of cervical cancer but could not precisely define the anatomic location of the cancer and the sensitivity was not superior than MRI. Earlier detection of metastatic lymph nodes was superior than CT/MRI (sensitivity; 100 %) for metastatic lymph nodes. Also we found 3 double primary cancers incidentally (2 lung cancers and 1 thyroid cancer). In conclusion, FDG-FET scan might be useful for the earlier of hidden lesions that cannot be detected by routine conventional methods and differential diagnosis with radiation fibrosis and benign lymph adenophy.

Scan path entropy and Arrow plots: Capturing scanning behavior of multiple observers

Directory of Open Access Journals (Sweden)

Ignace T C Hooge

2013-12-01

Full Text Available Designers of visual communication material want their material to attract and retain attention. In marketing research, heat maps, dwell time, and time to AOI first hit are often used as evaluation parameters. Here we present two additional measures 1 scan path entropy to quantify gaze guidance and 2 the arrow plot to visualize the average scan path. Both are based on string representations of scan paths. The latter also incorporates transition matrices and time required for 50% of the observers to first hit AOIs (T50. The new measures were tested in an eye tracking study (48 observers, 39 advertisements. Scan path entropy is a sensible measure for gaze guidance and the new visualization method reveals aspects of the average scan path and gives a better indication in what order global scanning takes place.

Sex differences in foreign language text comprehension : The role of interests and prior knowledge

NARCIS (Netherlands)

Bügel, K; Buunk, Abraham (Bram)

1996-01-01

The scores obtained by female students on the national foreign language examinations in the Netherlands have been slightly but consistently lower than those of male students. The present research among 2980 high school students tested the hypothesis that, owing to sex differences in prior knowledge

Evaluation of aluminosilicate glass sintering during differential scanning calorimetry

International Nuclear Information System (INIS)

Souza, Juliana Pereira de

2015-01-01

In this work a difference in the baseline in differential scanning calorimetry analyses, observed in a work where aluminosilicate glasses microspheres containing Ho were studied for application in selective internal radiotherapy as hepatocellular carcinoma treatment, was studied. The glasses with nominal composition 53,7 SiO 2 .10,5 Al 2 O 3 . 35,8 MgO in %mol were produced from traditional melting. The first obtained were milled and sieved in the range of 45 a 63 μm. The material was used to produce glass microspheres by the gravitational fall method. The glass powder and the microspheres were characterized by X ray fluorescence spectrometry, laser diffraction, X ray diffraction, differential scanning calorimetry, differential thermal analysis, thermogravimetry, mass spectrometry, and scanning electron microscopy. After the thermal analyses, pellets were formed in the crucibles and were analyzed by scanning electron microscopy, X ray diffraction, and He pycnometry. The difference in the baseline was associated to the viscous flow sintering process and happens because of the decrease in the detected heat flow due to the sample shrinkage. Other events as concurrent crystallization with the sintering process were also studied. (author)

The detectability of hepatic metastases in candidates of radiofrequency ablation: comparison for helical CT scanning and late-phase pulse-inversion harmonic imaging

Energy Technology Data Exchange (ETDEWEB)

Lee, Kang Won; Yoon, Kwon Ha; Kim, Eun A; Park, Ki Han; Juhng, Seon Kwan; Won, Jong Jin [School of Medicine, Wonkwang Univ., Iksan (Korea, Republic of)

2002-02-01

To compare dual-phase helical CT and pulse inversion harmonic US using microbubble contrast agents in the detection of hepatic metastases prior to radiofrequency (RF) ablation. Twenty-one patients in whom hepatic metastases from colorectal cancer had been diagnosed by dual-phase CT scanning and who were considered to be candidates for RF ablation underwent pulse-inversion barmonic US examination. Images were obtained 5 minutes after the bolus injection of microbubble contrast agent SH U 508 A (4.0 g, 300 mg/mL). The number of metastatic tumors revealed by CT and US was determined, and the findings were statistically analysed. The influence of the results of US examination on treatment planning was also evaluated. In 21 patients, 48 metastaic lesions were detected by helical CT, and 56 lesions by US. These eight additional lesions revealed by US occurred in six patients (29%), and their diameter was 3-13 (mean, 7.2) mm. In three of these patients, RF ablation could not be performed ,while in the other three, the additional lesions were ablated. Pulse-inversion harmonic US imaging using microbubble contrast agents may depict small hepatic metastatic tumors that were not apparent at CT. US-therefore appears to be useful in the planning of treatment prior to the RF ablation of hepatic metastases.

Use of laser-scan technology to analyse topography and flow in a weir pool

Directory of Open Access Journals (Sweden)

P. E. Dresel

2012-08-01

Full Text Available The development of laser-scan techniques provides opportunity for detailed terrain analysis in hydrologic studies. Ground based scans were used to model the ground surface elevation in the area of a stream gauge weir over an area of 240 m² at a resolution of 0.05 m. The terrain model was used to assess the possibility of flow bypassing the weir and to calculate stream flow during filling of the weir pool, prior to flow through the weir notch. The mapped surface shows a subtle low-lying area at the south end of the structure where flow could bypass the weir. The flow calculations quantify low-flows that do not reach the weir notch during small rain events and flow at the beginning of larger events in the ephemeral stream.

Divergent Priors and well Behaved Bayes Factors

NARCIS (Netherlands)

R.W. Strachan (Rodney); H.K. van Dijk (Herman)

2011-01-01

textabstractDivergent priors are improper when defined on unbounded supports. Bartlett's paradox has been taken to imply that using improper priors results in ill-defined Bayes factors, preventing model comparison by posterior probabilities. However many improper priors have attractive properties

Metastatic calcification of the stomach imaged on a bone scan

Energy Technology Data Exchange (ETDEWEB)

Goldstein, R.; Ryo, U.Y.; Pinsky, S.M.

1984-10-01

A whole body bone scan obtained on a 21-year-old woman with sickle cell disease and chronic renal failure showed localization of the radionuclide diffusely in the stomach. The localization of the radionuclide represented metastatic calcification of the stomach caused by secondary hyperparathyroidism.

Analysis of ADU structure obtained under different precipitation conditions

International Nuclear Information System (INIS)

Ramella, Jose L.; Esteban, Adolfo; Mendez De Leo, Lucia P.; Sassone, Ariel; Novara, Oscar E.; Boero, Norma L.; Leyva, Ana G.

1999-01-01

ADU is the nominal name for ammonium poly uranate. It is a very complex compound of polymeric structure, which may have, according to precipitation conditions, different chemical composition and crystallographic structure. ADU is used as uranium oxide precursor in the manufacture of fuel elements. In former papers it was proved that if ultrasound is applied during precipitation and digestion the characteristics of the final product (U 3 O 8 UO 2 ) improve. By studying ADU thermal decomposition obtained by ultrasonic application, it was intended to obtain its composition. Therefore, differential thermal gravimetric and differential thermal analyses were performed. Samples were taken from special points and analyzed by X-ray diffraction, infra-red spectroscopy and scanning. An experiment was also designed to identify the products released during heating. Results and conclusions obtained are presented in this work. (author)

Estimation of forest resources from a country wide laser scanning survey and national forest inventory data

DEFF Research Database (Denmark)

Nord-Larsen, Thomas; Schumacher, Johannes

2012-01-01

Airborne laser scanning may provide a means for assessing local forest biomass resources. In this study, national forest inventory (NFI) data was used as reference data for modeling forest basal area, volume, aboveground biomass, and total biomass from laser scanning data obtained in a countrywid...

Bone scanning in the child and young adult. Pt. 2

Energy Technology Data Exchange (ETDEWEB)

Murray, I P.C. [Prince of Wales Hospital, Randwick (Australia). Dept. of Nuclear Medicine

1980-01-01

The sensitivity of the radionuclide bone scan in identifying osteoblastic reaction in bone and in detecting local alterations in blood flow is valuable in many benign diseases involving bone, particularly those which are more common in children and young adults, and in which early detection may be critical to future health. Bone scanning offers a simple yet reliable means for establishing an early diagnosis, evaluating the extent of the disease, and assessing the therapeutic response in disorders resulting from infection, trauma, or vascular insult. Useful information may also be obtained in disturbances of growth and development, and in congenital lesions.

Scanning control and data acquisition interface for a spectroscopy diagnostic

International Nuclear Information System (INIS)

Lopez-Callejas, R.; Galindo, S.; Benitez-Read, J.S.; Pacheco-Sotelo, J.; Longoria-Gandara, L.C.; Valencia-Alvarado, R.

2001-01-01

This work presents the design of a PC supported interface unit that improves the operation of a mechanically driven Czerny-Turner monochromator to the point of meeting the conditions required to be useful in wavelength separation and spectrum analysis for breakdown and conditioning discharges in plasma physics diagnostics. The PC supported interface verifies and sets the position and scan range of the instrument scanning drive. The interface consists of a microcontroller and its associated circuitry. The microcontroller is also used as a data acquisition and data manipulation element. An example of obtained spectra illustrating the instrument greatly improved performance is presented

Theoretical approach to the scanning tunneling microscope

International Nuclear Information System (INIS)

Noguera, C.

1990-01-01

Within a one-electron approach, based on a Green's-function formalism, a nonperturbative expression for the tunneling current is obtained and used to discuss which spectroscopic information may be deduced from a scanning-tunneling-microscope experiment. It is shown up to which limits the voltage dependence of the tunneling current reproduces the local density of states at the surface, and how the reflection coefficients of the electronic waves at the surface may modify it

Characterization of poly(3-hydroxybutyrate) mats obtained by electro spinning method

International Nuclear Information System (INIS)

Goncalves, Joel; Branciforti, Marcia C.; Bretas, Rosario E.S.; Agnelli, Jose A.M.

2009-01-01

Nanofibers of poly-3-hydroxybutyrate (PHB) were produced by electro spinning of chloroform/dimethylformamide (90 / 10% v/v) solutions. The influence of the solution concentration on the processing, morphology and properties of the nanofibers was evaluated. The nanofibers were characterized by wide-angle X-ray diffraction. The nanofibers morphology was evaluated by scanning electron microscopy (SEM). The thermal properties of the nanofibers were analyzed by differential scanning calorimetry (DSC). The results show that the obtained PHB nanofibers exhibit small average diameter (<500 nm) and narrow diameter distribution. A decrease in the fibers average diameters of PHB fibers with the decrease of the solution concentration was observed. The nanofibers were observed to be less crystalline than pure polymer. (author)

Examination of irradiated fuel elements using gamma scanning technique

International Nuclear Information System (INIS)

Ichim, O.; Mincu, M.; Man, I.; Stanica, M.

2016-01-01

The purpose of this paper is to validate the gamma scanning technique used to calculate the activity of gamma fission products from CANDU/TRIGA irradiated fuel elements. After a short presentation of the equipments used and their characteristics, the paper describes the calibration technique for the devices and how computed tomography reconstruction is done. Following the previously mentioned steps is possible to obtain the axial and radial profiles and the computed tomography reconstruction for calibration sources and for the irradiated fuel elements. The results are used to validate the gamma scanning techniques as a non-destructive examination method. The gamma scanning techniques will be used to: identify the fission products in the irradiated CANDU/TRIGA fuel elements, construct the axial and radial distributions of fission products, get the distribution in cross section through computed tomography reconstruction, and determine the nuclei number and the fission products activity of the irradiated CANDU/TRIGA fuel elements. (authors)

Imaging ballistic carrier trajectories in graphene using scanning gate microscopy

Energy Technology Data Exchange (ETDEWEB)

Morikawa, Sei; Masubuchi, Satoru [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Dou, Ziwei; Wang, Shu-Wei; Smith, Charles G.; Connolly, Malcolm R., E-mail: mrc61@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Watanabe, Kenji; Taniguchi, Takashi [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Machida, Tomoki, E-mail: tmachida@iis.u-tokyo.ac.jp [Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan)

2015-12-14

We use scanning gate microscopy to map out the trajectories of ballistic carriers in high-mobility graphene encapsulated by hexagonal boron nitride and subject to a weak magnetic field. We employ a magnetic focusing geometry to image carriers that emerge ballistically from an injector, follow a cyclotron path due to the Lorentz force from an applied magnetic field, and land on an adjacent collector probe. The local electric field generated by the scanning tip in the vicinity of the carriers deflects their trajectories, modifying the proportion of carriers focused into the collector. By measuring the voltage at the collector while scanning the tip, we are able to obtain images with arcs that are consistent with the expected cyclotron motion. We also demonstrate that the tip can be used to redirect misaligned carriers back to the collector.

Diagnostic evaluation of the adrenal scanning using 131I-adosterol

International Nuclear Information System (INIS)

Sugawara, Seiya; Nakamura, Mamoru; Sawai, Yoshikazu; Fukuchi, Soitsu.

1978-01-01

We have performed adrenal scanning in the 30 patients with suspected adrenal disorders eight days after the intravenous administration of about 500 μCi of 131 I-adosterol (NCL-6- 131 I), using 5 inch crystal rectilinear scintiscanner. Successful image of the adrenals was obtained in all the patients. In the 30 patients, 27 were proved to have adrenal disorders by surgical and hormonal findings. In 13 patients with primary aldosteronism, the side of adrenal adenoma was diagnosed correctly in all the cases by adrenal scanning. We could detected a small aldosterone-producing adenoma which measured 11 x 8 x 6 mm in size. In two patients with idiopathic hyperaldosteronism, asymmetrical radio-uptake between the two adrenals was seen on the standard scanning, and it was difficult to differentiate between tumor or hyperplasia. Dexamethazone-modified suppression scanning was very effective in lateralizing adenomas in the patients with primary aldosteronism. Two patients with Cushing's syndrome due to adrenal hyperplasia showed prominent and almost equal radioactivity of both the adrenal glands. Adrenal adenomas in 8 patients with Cushing's syndrome were definitely visualized on adrenal scanning, with no uptake in the contralateral sides. In one patient with Cushing's syndrome due to an adrenal carcinoma, adrenal scanning showed significant activity in the area of the carcinoma, and no uptake on the opposite side. In one patient with adrenogenital syndrome due to a virilizing adenoma with focal malignancy, adrenal scanning showed high radioactivity in the region of the tumor, and moderate activity on the opposite side. Also in the case of adrenal carcinoma, we appreciated diagnostic value of the adrenal scanning utilizing 131 I-adosterol. (author)

Washing of waste prior to landfilling.

Science.gov (United States)

Cossu, Raffaello; Lai, Tiziana

2012-05-01

The main impact produced by landfills is represented by the release of leachate emissions. Waste washing treatment has been investigated to evaluate its efficiency in reducing the waste leaching fraction prior to landfilling. The results of laboratory-scale washing tests applied to several significant residues from integrated management of solid waste are presented in this study, specifically: non-recyclable plastics from source separation, mechanical-biological treated municipal solid waste and a special waste, automotive shredded residues. Results obtained demonstrate that washing treatment contributes towards combating the environmental impacts of raw wastes. Accordingly, a leachate production model was applied, leading to the consideration that the concentrations of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN), parameters of fundamental importance in the characterization of landfill leachate, from a landfill containing washed wastes, are comparable to those that would only be reached between 90 and 220years later in the presence of raw wastes. The findings obtained demonstrated that washing of waste may represent an effective means of reducing the leachable fraction resulting in a consequent decrease in landfill emissions. Further studies on pilot scale are needed to assess the potential for full-scale application of this treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Decommissioning and dismantling: Qualification of the gamma scanning method as a certified method for radiological decontrolling measurement. Final report; Stillegung und Rueckbau: Qualifizierung des Gamma-Scanning zur Freimessung. Genehmigungspraxis. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Kirchhoff, J.; Stasch, W.P.

1998-10-01

Prior to release from the radiological supervision and control regime of the AtG (German Atomic Energy Act), nuclear facilities have to be scanned using licensed radioactivity measuring methods for providing evidence that the remaining radioactive contamination is below the legally defined limits and excludes hazards to the population, material goods, or the environment. The manually performed {alpha}/{beta} measuring methods applied so far for radiological decontrolling measurement are surface scanning methods measuring the contamination of very thin surface layers of the structures, while radioactivity in deeper layers is not necessarily detected. The gamma scanning method presented in this document is capable of scanning the structures and materials of nuclear facilities from the surface down to much deeper layers in just one measuring run. The automated scanning process at the same time offers the advantage of preventing the uncertainties possibly contributed through human factors. (orig./CB) [Deutsch] Vor der Entlassung von kerntechnischen Anlagen aus dem Geltungsbereich des AtG ist sicherzustellen, dass von der Anlage nach Freigabe aus der atomrechtlichen Ueberwachung keine Gefahren fuer Personen, Sachgueter und die Umwelt ausgehen koennen. Hierzu sind die Anlagen freizumessen, d.h. es ist durch qualifizierte Messverfahren sicherzustellen, dass festgelegte radiologische Grenzwerte unterschritten werden. Die bisherigen auf {alpha}/{beta}-Messung beruhenden Freimessverfahren (Kontaminationsmonitore) erfassen nur die Radioaktivitaet in duennsten Oberflaechenschichten. Radioaktivitaet in darunter liegenden Schichten wird nicht zwangslaeufig erfasst. Zudem erfolgen diese Messungen ausschliesslich manuell. Das Gamma-Scanning-Freimessverfahren erfasst neben der Oberflaechenschicht gleichzeitig auch tiefere Schichten. Der Nachweis der Grenzwertunterschreitung kann somit in nur einem Arbeitsgang erbracht werden. Durch automatisiertes Scannen koennte darueber hinaus

Beam-Beam effects at the CMS BRIL van-der-Meer scans

CERN Document Server

CMS Collaboration

2017-01-01

The CMS Beam Radiation Instrumentation and Luminosity Project (BRIL) is devoted to the simulation and measurement of luminosity, beam conditions and radiation fields in the CMS Experiment at CERN. The project is engaged in operating and developing new detectors, compatible with the high luminosity experimental environments at the LHC. BRIL operates several detectors based on different physical principles and technologies. The detectors are calibrated using van-der-Meer scans to measure the luminosity that is a fundamental quantity of the LHC beam. In van-der-Meer scans the count rate in a detector is measured as a function of the distance between beams in the plane perpendicular to beam direction, to extract the underlying beam overlap area. The goal of the van-der-Meer scans is to obtain the calibration constant for each luminometer to be used at calibration then in physics data taking runs. The note presents the overview of beam-beam effects at the van-der-Meer scan and the corresponding corrections that sh...

A Two-Stage Maximum Entropy Prior of Location Parameter with a Stochastic Multivariate Interval Constraint and Its Properties

Directory of Open Access Journals (Sweden)

Hea-Jung Kim

2016-05-01

Full Text Available This paper proposes a two-stage maximum entropy prior to elicit uncertainty regarding a multivariate interval constraint of the location parameter of a scale mixture of normal model. Using Shannon’s entropy, this study demonstrates how the prior, obtained by using two stages of a prior hierarchy, appropriately accounts for the information regarding the stochastic constraint and suggests an objective measure of the degree of belief in the stochastic constraint. The study also verifies that the proposed prior plays the role of bridging the gap between the canonical maximum entropy prior of the parameter with no interval constraint and that with a certain multivariate interval constraint. It is shown that the two-stage maximum entropy prior belongs to the family of rectangle screened normal distributions that is conjugate for samples from a normal distribution. Some properties of the prior density, useful for developing a Bayesian inference of the parameter with the stochastic constraint, are provided. We also propose a hierarchical constrained scale mixture of normal model (HCSMN, which uses the prior density to estimate the constrained location parameter of a scale mixture of normal model and demonstrates the scope of its applicability.

Prospective evaluation of the super scan of metabolic bone disease (abstract)

International Nuclear Information System (INIS)

Khan, A.U.; Ahmad, S.; Khan, A.A.; Khan, S.M.; Rauf, M.

1999-01-01

A total of 27 cases (23 females and 4 males) having super scan of metabolic bone disease were prospectively evaluated over a period of 2 years (Jan. 1997 to Dec. 1998) at the Nuclear Medicine Department (NMD), institute of Radiotherapy and Nuclear Medicine (IRNUM), Peshawar to identify various causes for the super scan picture on Tc-99m MDP bone scintigraphy in our clinical environment. After the three observer confirmation of the bone scan, the serum calcium and Parathyroid Hormone (PTH) estimation was done. The patients having serum PTH greater than 250 Pg/L under went two phase Parathyroid MIBI Scintigraphy 2PP MIBI scan) for the detection of parathyroid adenoma. The patients having positive scans for parathyroid Adenoma were subjected to surgery and histopathological confirmation was obtained. Selected cases under went a trial of deport preparation of vitamin D3 calcium supplementation. The final diagnosis of 16 patients was osteomalacia (59%), six patients had histopathologically confirmed parathyroid adenoma (22.2%), one case each was that of toxic thyroid adenoma (3.7%) and chronic renal failure (3.7%). In three cases the final diagnosis was not reached (11.21%). Osteomalacia and parathyroid adenoma are the two most common causes for the super scan picture on bone scintigraphy. (author)

Mössbauer Magnetic Scan experiments

Energy Technology Data Exchange (ETDEWEB)

Pasquevich, G.A., E-mail: gpasquev@fisica.unlp.edu.ar [Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, P.O. Box 67, 1900 La Plata (Argentina); Instituto de Física La Plata, CONICET, P.O. Box 67, 1900 La Plata (Argentina); Facultad de Ingeniería, Universidad Nacional de La Plata, P.O. Box 91, 1900 La Plata (Argentina); Mendoza Zélis, P. [Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, P.O. Box 67, 1900 La Plata (Argentina); Instituto de Física La Plata, CONICET, P.O. Box 67, 1900 La Plata (Argentina); Facultad de Ingeniería, Universidad Nacional de La Plata, P.O. Box 91, 1900 La Plata (Argentina); Lencina, A. [Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, P.O. Box 67, 1900 La Plata (Argentina); Centro de Investigaciones Ópticas (CONICET La Plata – CIC), P.O. Box 3, 1897 Gonnet (Argentina); Veiga, A. [Instituto de Física La Plata, CONICET, P.O. Box 67, 1900 La Plata (Argentina); Facultad de Ingeniería, Universidad Nacional de La Plata, P.O. Box 91, 1900 La Plata (Argentina); Fernández van Raap, M.B.; Sánchez, F.H. [Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, P.O. Box 67, 1900 La Plata (Argentina); Instituto de Física La Plata, CONICET, P.O. Box 67, 1900 La Plata (Argentina)

2014-06-01

We report an application of the Mössbauer Effect designed to retrieve specific information on the magnetic response of iron-containing materials. It consists in the measurement of the nuclear absorption of gamma-rays as a function of an external magnetic field for a specific nuclear transition between magnetically-split nuclear levels. The experiments, here termed Mössbauer Magnetic Scan experiments, were carried out recording the absorption of {sup 57}Fe 14.4 keV gamma-ray in α-Fe at constant Doppler energies coincident with some of the spectral lines of the magnetically split Mössbauer spectrum. Due to the dependence of the transition probabilities on the relative orientation between the nuclear magnetic moment and the gamma-ray direction, the present application results in a useful method to study the magnetic-field evolution of the distribution of atomic-magnetic-moment orientations. The proposed technique inherit from the Mössbauer Spectroscopy the chemical-element selectiveness as well as the ability to differentiate responses from iron atoms located at inequivalent site or at different phases. In this work, we show that the data analysis for these experiments depends on the sample thickness that the gamma-ray has to cross. For thin samples (i.e.samples with Mössbauer effective thicknesses lower than one) the magnetic-field dependence of the second-order-moment of the orientation distribution in the direction of the gamma ray is obtained. On the other hand, for thicker samples, although the data analysis is more complex, the dependences of the three second-order-moments of the orientation distribution are obtained. The experiments were performed on two α-Fe foils of different Mössbauer effective thicknesses. They were chosen to represent the cases of thin and thick Mössbauer absorbers. The magnetic evolution of the orientations distribution is compared with results obtained from magnetometric measurements showing a good agreement as well indicating

Mössbauer Magnetic Scan experiments

Science.gov (United States)

Pasquevich, G. A.; Mendoza Zélis, P.; Lencina, A.; Veiga, A.; Fernández van Raap, M. B.; Sánchez, F. H.

2014-06-01

We report an application of the Mössbauer Effect designed to retrieve specific information on the magnetic response of iron-containing materials. It consists in the measurement of the nuclear absorption of gamma-rays as a function of an external magnetic field for a specific nuclear transition between magnetically-split nuclear levels. The experiments, here termed Mössbauer Magnetic Scan experiments, were carried out recording the absorption of 57Fe 14.4 keV gamma-ray in α-Fe at constant Doppler energies coincident with some of the spectral lines of the magnetically split Mössbauer spectrum. Due to the dependence of the transition probabilities on the relative orientation between the nuclear magnetic moment and the gamma-ray direction, the present application results in a useful method to study the magnetic-field evolution of the distribution of atomic-magnetic-moment orientations. The proposed technique inherit from the Mössbauer Spectroscopy the chemical-element selectiveness as well as the ability to differentiate responses from iron atoms located at inequivalent site or at different phases. In this work, we show that the data analysis for these experiments depends on the sample thickness that the gamma-ray has to cross. For thin samples (i.e.samples with Mössbauer effective thicknesses lower than one) the magnetic-field dependence of the second-order-moment of the orientation distribution in the direction of the gamma ray is obtained. On the other hand, for thicker samples, although the data analysis is more complex, the dependences of the three second-order-moments of the orientation distribution are obtained. The experiments were performed on two α-Fe foils of different Mössbauer effective thicknesses. They were chosen to represent the cases of thin and thick Mössbauer absorbers. The magnetic evolution of the orientations distribution is compared with results obtained from magnetometric measurements showing a good agreement as well indicating the

Gamma-ray scanning of neutron activated geological sediments for studying elemental profile distributions

International Nuclear Information System (INIS)

Ellinger, M.; Janghorbani, M.; Starke, K.

1976-01-01

Gamma-ray scanning for application to elemental profile studies of geological samples was studied with a neutron activated Baltic Shield sediment. Profile distribution of seven elements were measured. The capabilities and limitations of gamma-ray scanning are discussed by comparing the results with profiles obtained after the mechanical subdivision of the sample and the activation of the appropriately sized separates. With respect to the merits and limitations of scanning gamma-ray spectrometry applied to activated complex matrices the following conclusions were drawn. Qualitatively, the scanning method yields the same information as the much more laborious method of mechanical sudbisubdivision. Quantitatively, it is significantly less accurate. The scanning method has the significant advantage of allowing preservation of the sample. This could be important for such speciments as lunar and archeological materials. The method reduces sample preparation time and the possibility of sample contamination. (T.G.)

Lens thickness assessment: anterior segment optical coherence tomography versus A-scan ultrasonography

Directory of Open Access Journals (Sweden)

Nikoo Hamzeh

2015-12-01

Full Text Available AIM: To assess lens thickness measurements with anterior segment-optical coherence tomography (AS-OCT in comparison with A-scan ultrasonography (A-scan US. METHODS: There were 218 adult subjects (218 eyes aged 59.2±9.2y enrolled in this prospective cross-sectional study. Forty-three eyes had open angles and 175 eyes had narrow angles. Routine ophthalmic exam was performed and nuclear opacity was graded using the Lens Opacities Classification System III (LOCS III. Lens thickness was measured by AS-OCT (Visante OCT, Carl Zeiss Meditec, Dublin, CA, USA. The highest quality image was selected for each eye and lens thickness was calculated using ImageJ software. Lens thickness was also measured by A-scan US. RESULTS: Interclass correlations showed a value of 99.7% for intra-visit measurements and 95.3% for inter-visit measurements. The mean lens thickness measured by AS-OCT was not significantly different from that of A-scan US (4.861±0.404 vs 4.866±0.351 mm, P=0.74. Lens thickness values obtained from the two instruments were highly correlated overall (Pearson correlation coefficient=0.81, P<0.001, and in all LOCS III specific subgroups except in grade 5 of nuclear opacity. Bland-Altman analysis revealed a 95% limit of agreement from -0.45 to 0.46 mm. Lens thickness difference between the two instruments became smaller as the lens thickness increased and AS-OCT yielded smaller values than A-scan US in thicker lens (β=-0.29, P<0.001 CONCLUSION: AS-OCT-derived lens thickness measurement is valid and comparable to the results obtained by A-scan US. It can be used as a reliable noncontact method for measuring lens thickness in adults with or without significant cataract.

Volumetric measurement of the maxillary sinus by coronal CT scan

International Nuclear Information System (INIS)

Ikeda, Atsuko

1996-01-01

The volume of the maxillary sinus was estimated by coronal CT scan. The purpose of this study was to compare the estimated volume of the normal maxillary sinus with that of the inflamed maxillary sinus. Patients were classified following evaluation by CT scan of the paranasal sinuses into 3 categories. Group A (n=12): Patients suffered from headache, facial pain and epistaxis, but CT scans of their nasal cavity and paranasal sinus were within normal limits without inflammatory change. Group B (n=69): Patients with bilateral chronic maxillary sinusitis, CT scans of whom showed inflammatory changes in both maxillary sinuses. All of the patients in this group underwent sinus surgery after coronal CT scans. Group C (n=14): Patients with unilateral chronic maxillary sinusitis, CT scans of whom showed inflammatory change in unilateral maxillary sinuses. CT scans of these patients were measured by Plannimeter to take the area of each image of the maxillary sinus. Consecutively imaged areas were summated by integral calculus to obtain an estimate of the sinus volume. The mean maxillary sinus volume in the affected sinuses was significantly smaller than those in the contralateral normal sinuses (p<0.05, Wilcoxon-test). The various volumes of the maxillary sinuses and the developmental cause were discussed. Comparison of groups A with B suggested three distinct patterns; the maxillary sinus volume has decreased due to inflammatory changes in the bone. The small sinuses have a tendency to develop chronic inflammatory change. The aeration in the maxillary sinus may be decreased when anatomic variations that may obstruct the ethmoid infundibulum exist. (K.H.)

Volumetric measurement of the maxillary sinus by coronal CT scan

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Atsuko [Tokyo Medical and Dental Univ. (Japan). School of Medicine

1996-08-01

The volume of the maxillary sinus was estimated by coronal CT scan. The purpose of this study was to compare the estimated volume of the normal maxillary sinus with that of the inflamed maxillary sinus. Patients were classified following evaluation by CT scan of the paranasal sinuses into 3 categories. Group A (n=12): Patients suffered from headache, facial pain and epistaxis, but CT scans of their nasal cavity and paranasal sinus were within normal limits without inflammatory change. Group B (n=69): Patients with bilateral chronic maxillary sinusitis, CT scans of whom showed inflammatory changes in both maxillary sinuses. All of the patients in this group underwent sinus surgery after coronal CT scans. Group C (n=14): Patients with unilateral chronic maxillary sinusitis, CT scans of whom showed inflammatory change in unilateral maxillary sinuses. CT scans of these patients were measured by Plannimeter to take the area of each image of the maxillary sinus. Consecutively imaged areas were summated by integral calculus to obtain an estimate of the sinus volume. The mean maxillary sinus volume in the affected sinuses was significantly smaller than those in the contralateral normal sinuses (p<0.05, Wilcoxon-test). The various volumes of the maxillary sinuses and the developmental cause were discussed. Comparison of groups A with B suggested three distinct patterns; the maxillary sinus volume has decreased due to inflammatory changes in the bone. The small sinuses have a tendency to develop chronic inflammatory change. The aeration in the maxillary sinus may be decreased when anatomic variations that may obstruct the ethmoid infundibulum exist. (K.H.)

Dose profile variation with voltage in head CT scans using radiochromic films

Science.gov (United States)

Mourão, A. P.; Alonso, T. C.; DaSilva, T. A.

2014-02-01

The voltage source used in an X-ray tube is an important part of defining the generated beam spectrum energy profile. The X-ray spectrum energy defines the X-ray beam absorption as well as the characteristics of the energy deposition in an irradiated object. Although CT scanners allow one to choose between four different voltage values, most of them employ a voltage of 120 kV in their scanning protocols, regardless of the patient characteristics. Based on this fact, this work investigated the deposited dose in a polymethyl methacrylate (PMMA) cylindrical head phantom. The entire volume was irradiated twice. Two CT scanning protocols were used with two different voltage values: 100 and 120 kV. The phantom volume was irradiated, and radiochromic films were employed to record dose profiles. Measurements were conducted with a calibrated pencil ionization chamber, which was positioned in the center and in four peripheral bores of the head PMMA phantom, to calibrate the radiochromic films. The central slice was then irradiated. This procedure allowed us to find the conversion factors necessary to obtain dose values recorded in the films. The data obtained allowed us to observe the dose variation profile inside the phantom head as well as in the peripheral and central regions. The peripheral region showed higher dose values than those of the central region for scans using both voltage values: approximately 31% higher for scanning with 120 kV and 25% higher with 100 kV. Doses recorded with the highest voltage are significantly higher, approximately 50% higher in the peripheral region and 40% higher in the central region. A longitudinal variation could be observed, and the maximum dose was recorded at the peripheral region, at the midpoint of the longitudinal axis. The obtained results will most likely contribute to the dissemination of proper procedure as well as to optimize dosimetry and tests of quality control in CT because the choice of protocols with different voltage

Computer-assisted sequential quantitative analysis of gallium scans in pulmonary sarcoidosis

International Nuclear Information System (INIS)

Rohatgi, P.K.; Bates, H.R.; Noss, R.W.

1985-01-01

Fifty-one sequential gallium citrate scans were performed in 22 patients with biopsy-proven sarcoidosis. A computer-assisted quantitative analysis of these scans was performed to obtain a gallium score. The changes in gallium score were correlated with changes in serum angiotensin converting enzyme (SACE) activity and objective changes in clinical status. There was a good concordance between changes in gallium score, SACE activity and clinical assessment in patients with sarcoidosis, and changes in gallium index were slightly superior to SACE index in assessing activity of sarcoidosis. (author)

Gamma ray scanning as troubleshooting tool for unusual and large diameter refinery vacuum columns

International Nuclear Information System (INIS)

Sarkar, T.K.; Chawla, R.; Banik, S.; Chopra, S.J.; Singh, G.; Pant, H.J.; Sreeramakrishnan, P.; Dhar, D.C.; Pushpangathan, P.N.; Sharma, V.K.

1997-01-01

Gamma scanning of trayed and packed columns is widely used to obtain density profiles and identify on-line problems such as: damaged tray or packing, foaming, flooding, maldistribution, weeping and entrainment, etc. However, scanning of large diameter tray or packed columns requires expertise in handling high intensity gamma sources along with thorough understanding of distillation engineering. Engineers India Limited and the Bhabha Atomic Research Centre undertook scanning of two such large diameter (8.4 m and 7.4 m) trayed and packed refinery vacuum distillation columns and successfully diagnosed the problems and suggested remedial actions. Radiography testing of small diameter columns can be used to confirm gamma scanning results. One such example for ammonia separator column is given

Hepatobiliary scanning in cardiac transplant patients maintained on cyclosporine

International Nuclear Information System (INIS)

Dhekne, R.D.; Long, S.E.; Moore, W.H.; Frazier, O.H.

1987-01-01

Many patients receiving cyclosporine (CSA) develop hepatic dysfunction or pancreatitis. The authors reviewed 106 records of cardiac transplant patients maintained on CSA. Eleven patients underwent 16 hepatobiliary scans (HBSs) for abdominal pain and/or abnormal liver function. Of 16 HBSs, ten demonstrated normal gallbladder visualization. Follow-up in all cases confirmed scan findings. Five patients had no gallbladder visualization; confirmation of acute cholecystitis was obtained by surgery in two and by autopsy in three. One patient had previous cholecystectomy. The authors found HPS useful for evaluating acute cholecystitis in patients receiving CSA with or without associated drug-related pancreatitis and hepatic insufficiency and suggest that HBS can assist in the selection of patients for CSA dose adjustment

Radiopharmaceutical scanning agents

International Nuclear Information System (INIS)

1976-01-01

This invention is directed to dispersions useful in preparing radiopharmaceutical scanning agents, to technetium labelled dispersions, to methods for preparing such dispersions and to their use as scanning agents

Towards real-time topical detection and characterization of FDG dose infiltration prior to PET imaging

Energy Technology Data Exchange (ETDEWEB)

Williams, Jason M.; Arlinghaus, Lori R. [Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN (United States); Rani, Sudheer D. [Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN (United States); Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, TN (United States); Shone, Martha D. [Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, TN (United States); Abramson, Vandana G. [Vanderbilt University Medical Center, Department of Medicine, Nashville, TN (United States); Vanderbilt-Ingram Cancer Center, Nashville, TN (United States); Pendyala, Praveen [Vanderbilt University Medical Center, Department of Radiation Oncology, Nashville, TN (United States); Chakravarthy, A.B. [Vanderbilt-Ingram Cancer Center, Nashville, TN (United States); Vanderbilt University Medical Center, Department of Radiation Oncology, Nashville, TN (United States); Gorge, William J.; Knowland, Joshua G.; Lattanze, Ronald K.; Perrin, Steven R. [Lucerno Dynamics, LLC, Morrisville, NC (United States); Scarantino, Charles W. [Lucerno Dynamics, LLC, Morrisville, NC (United States); University of North Carolina, Department of Radiation Oncology, Chapel Hill, NC (United States); Townsend, David W. [Lucerno Dynamics, LLC, Morrisville, NC (United States); Technology and Research-National University of Singapore, Clinical Imaging Research Centre, Agency for Science, Singapore (Singapore); Abramson, Richard G. [Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN (United States); Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, TN (United States); Vanderbilt-Ingram Cancer Center, Nashville, TN (United States); Yankeelov, Thomas E. [The University of Texas at Austin, Institute for Computational and Engineering Sciences, and Departments of Biomedical Engineering and Internal Medicine, Austin, TX (United States)

2016-12-15

To dynamically detect and characterize {sup 18}F-fluorodeoxyglucose (FDG) dose infiltrations and evaluate their effects on positron emission tomography (PET) standardized uptake values (SUV) at the injection site and in control tissue. Investigational gamma scintillation sensors were topically applied to patients with locally advanced breast cancer scheduled to undergo limited whole-body FDG-PET as part of an ongoing clinical study. Relative to the affected breast, sensors were placed on the contralateral injection arm and ipsilateral control arm during the resting uptake phase prior to each patient's PET scan. Time-activity curves (TACs) from the sensors were integrated at varying intervals (0-10, 0-20, 0-30, 0-40, and 30-40 min) post-FDG and the resulting areas under the curve (AUCs) were compared to SUVs obtained from PET. In cases of infiltration, observed in three sensor recordings (30 %), the injection arm TAC shape varied depending on the extent and severity of infiltration. In two of these cases, TAC characteristics suggested the infiltration was partially resolving prior to image acquisition, although it was still apparent on subsequent PET. Areas under the TAC 0-10 and 0-20 min post-FDG were significantly different in infiltrated versus non-infiltrated cases (Mann-Whitney, p < 0.05). When normalized to control, all TAC integration intervals from the injection arm were significantly correlated with SUV{sub peak} and SUV{sub max} measured over the infiltration site (Spearman ρ ≥ 0.77, p < 0.05). Receiver operating characteristic (ROC) analyses, testing the ability of the first 10 min of post-FDG sensor data to predict infiltration visibility on the ensuing PET, yielded an area under the ROC curve of 0.92. Topical sensors applied near the injection site provide dynamic information from the time of FDG administration through the uptake period and may be useful in detecting infiltrations regardless of PET image field of view. This dynamic information

Towards real-time topical detection and characterization of FDG dose infiltration prior to PET imaging

International Nuclear Information System (INIS)

Williams, Jason M.; Arlinghaus, Lori R.; Rani, Sudheer D.; Shone, Martha D.; Abramson, Vandana G.; Pendyala, Praveen; Chakravarthy, A.B.; Gorge, William J.; Knowland, Joshua G.; Lattanze, Ronald K.; Perrin, Steven R.; Scarantino, Charles W.; Townsend, David W.; Abramson, Richard G.; Yankeelov, Thomas E.

2016-01-01

To dynamically detect and characterize "1"8F-fluorodeoxyglucose (FDG) dose infiltrations and evaluate their effects on positron emission tomography (PET) standardized uptake values (SUV) at the injection site and in control tissue. Investigational gamma scintillation sensors were topically applied to patients with locally advanced breast cancer scheduled to undergo limited whole-body FDG-PET as part of an ongoing clinical study. Relative to the affected breast, sensors were placed on the contralateral injection arm and ipsilateral control arm during the resting uptake phase prior to each patient's PET scan. Time-activity curves (TACs) from the sensors were integrated at varying intervals (0-10, 0-20, 0-30, 0-40, and 30-40 min) post-FDG and the resulting areas under the curve (AUCs) were compared to SUVs obtained from PET. In cases of infiltration, observed in three sensor recordings (30 %), the injection arm TAC shape varied depending on the extent and severity of infiltration. In two of these cases, TAC characteristics suggested the infiltration was partially resolving prior to image acquisition, although it was still apparent on subsequent PET. Areas under the TAC 0-10 and 0-20 min post-FDG were significantly different in infiltrated versus non-infiltrated cases (Mann-Whitney, p < 0.05). When normalized to control, all TAC integration intervals from the injection arm were significantly correlated with SUV_p_e_a_k and SUV_m_a_x measured over the infiltration site (Spearman ρ ≥ 0.77, p < 0.05). Receiver operating characteristic (ROC) analyses, testing the ability of the first 10 min of post-FDG sensor data to predict infiltration visibility on the ensuing PET, yielded an area under the ROC curve of 0.92. Topical sensors applied near the injection site provide dynamic information from the time of FDG administration through the uptake period and may be useful in detecting infiltrations regardless of PET image field of view. This dynamic information may also

Nuclear Heart Scan

Science.gov (United States)

... Home / Nuclear Heart Scan Nuclear Heart Scan Also known as Nuclear Stress Test , ... Learn More Connect With Us Contact Us Directly Policies Privacy Policy Freedom of Information Act (FOIA) Accessibility ...

MutScan: fast detection and visualization of target mutations by scanning FASTQ data.

Science.gov (United States)

Chen, Shifu; Huang, Tanxiao; Wen, Tiexiang; Li, Hong; Xu, Mingyan; Gu, Jia

2018-01-22

Some types of clinical genetic tests, such as cancer testing using circulating tumor DNA (ctDNA), require sensitive detection of known target mutations. However, conventional next-generation sequencing (NGS) data analysis pipelines typically involve different steps of filtering, which may cause miss-detection of key mutations with low frequencies. Variant validation is also indicated for key mutations detected by bioinformatics pipelines. Typically, this process can be executed using alignment visualization tools such as IGV or GenomeBrowse. However, these tools are too heavy and therefore unsuitable for validating mutations in ultra-deep sequencing data. We developed MutScan to address problems of sensitive detection and efficient validation for target mutations. MutScan involves highly optimized string-searching algorithms, which can scan input FASTQ files to grab all reads that support target mutations. The collected supporting reads for each target mutation will be piled up and visualized using web technologies such as HTML and JavaScript. Algorithms such as rolling hash and bloom filter are applied to accelerate scanning and make MutScan applicable to detect or visualize target mutations in a very fast way. MutScan is a tool for the detection and visualization of target mutations by only scanning FASTQ raw data directly. Compared to conventional pipelines, this offers a very high performance, executing about 20 times faster, and offering maximal sensitivity since it can grab mutations with even one single supporting read. MutScan visualizes detected mutations by generating interactive pile-ups using web technologies. These can serve to validate target mutations, thus avoiding false positives. Furthermore, MutScan can visualize all mutation records in a VCF file to HTML pages for cloud-friendly VCF validation. MutScan is an open source tool available at GitHub: https://github.com/OpenGene/MutScan.

LIDAR COMBINED SCANNING UNIT

Directory of Open Access Journals (Sweden)

V. V. Elizarov

2016-11-01

Full Text Available Subject of Research. The results of lidar combined scanning unit development for locating leaks of hydrocarbons are presented The unit enables to perform high-speed scanning of the investigated space in wide and narrow angle fields. Method. Scanning in a wide angular field is produced by one-line scanning path by means of the movable aluminum mirror with a frequency of 20Hz and amplitude of 20 degrees of swing. Narrowband scanning is performed along a spiral path by the deflector. The deflection of the beam is done by rotation of the optical wedges forming part of the deflector at an angle of ±50. The control function of the scanning node is performed by a specialized software product written in C# programming language. Main Results. This scanning unit allows scanning the investigated area at a distance of 50-100 m with spatial resolution at the level of 3 cm. The positioning accuracy of the laser beam in space is 15'. The developed scanning unit gives the possibility to browse the entire investigated area for the time not more than 1 ms at a rotation frequency of each wedge from 50 to 200 Hz. The problem of unambiguous definition of the beam geographical coordinates in space is solved at the software level according to the rotation angles of the mirrors and optical wedges. Lidar system coordinates are determined by means of GPS. Practical Relevance. Development results open the possibility for increasing the spatial resolution of scanning systems of a wide range of lidars and can provide high positioning accuracy of the laser beam in space.

False-positive I-131 scan by contaminated muffler in a patient with thyroid carcinoma

Energy Technology Data Exchange (ETDEWEB)

Seo, Han Kyung; Kim, Min Woo; Jeong, Hwan Jeong; Sohn, Myung Hee [Chonbuk National University Hospital, Chonju (Korea, Republic of)

2006-02-15

A 39-year-old female patient who had undergone a total thyroidectomy for a papillary thyroid carcinoma underwent a whole body scan with I-131. The I-131 scan was performed 72 hours after administering 185 MBq (5 mGi) of an I-131 solution. The anterior image of head, neck, and upper chest showed multiple areas of increased uptake in the mediastinal area considering of functional metastasis. However, radioactivity was not evident in the image taken after removing her clothes and muffler. The image obtained after placing the muffler on the pallet showed that the radioactivity was still present. It is well known that artifacts on an I-131 scan can be produced by styling hair sputum, drooling during sleep, chewing gum, and paper or a cloth handkerchief that is contaminated with the radioactive iodine from either perspiration or saliva. This activity might be mistaken for a functional metastasis. Therefore, it is essential that an image be obtained after removing the patient's clothes. In this study, artifacts due to a contaminated muffler on the I-131 scan were found. These mimicked a functional metastasis of the mediastinal area in a patient with a papillary thyroid carcinoma.

On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

Science.gov (United States)

Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

2018-04-01

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

RADIOMETRIC CALIBRATION OF AIRBORNE LASER SCANNING DATA

OpenAIRE

Pilarska Magdalena

2016-01-01

Airborne laser scanning (ALS) is widely used passive remote sensing technique. The radiometric calibration of ALS data is presented in this article. This process is a necessary element in data processing since it eliminates the influence of the external factors on the obtained values of radiometric features such as range and incidence angle. The datasets were captured with three different laser scanners; since each of these operates at a different wavelength (532, 106 4 and 1550 nm) th...

Dose profile study on computerized tomography scanning of skull with simulator object

International Nuclear Information System (INIS)

Mourao, A.P.

2011-01-01

This work presents a comparison among the dose profiles in scanning of computerized tomography of a simulator object of PMMA in its periphery region. To obtain the deposited dose at the PMMA thermoluminescent dosemeters were used positioned at the interior of PMMA simulated object longitudinal to periphery and at the center of cylinder (positions denominated North, South, East, West and Center). Eight scanning were performed of simulator object using the routine protocol for skull in eight different services of radiodiagnostic by TC

Prior knowledge in recalling arguments in bioethical dilemmas

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Hiemke Katharina Schmidt

2015-09-01

Full Text Available Prior knowledge is known to facilitate learning new information. Normally in studies confirming this outcome the relationship between prior knowledge and the topic to be learned is obvious: the information to be acquired is part of the domain or topic to which the prior knowledge belongs. This raises the question as to whether prior knowledge of various domains facilitates recalling information. In this study 79 eleventh-grade students completed a questionnaire on their prior knowledge of seven different domains related to the bioethical dilemma of prenatal diagnostics. The students read a text containing arguments for and arguments against prenatal diagnostics. After one week and again 12 weeks later they were asked to write down all the arguments they remembered. Prior knowledge helped them recall the arguments one week (r = .350 and 12 weeks (r = .316 later. Prior knowledge of three of the seven domains significantly helped them recall the arguments one week later (correlations between r = .194 to r = .394. Partial correlations with interest as a control item revealed that interest did not explain the relationship between prior knowledge and recall. Prior knowledge of different domains jointly supports the recall of arguments related to bioethical topics.

Value of contrast enhanced CT scanning in the non-trauma emergency room patient

International Nuclear Information System (INIS)

Wood, L.P.; Parisi, M.; Finch, I.J.

1990-01-01

To determine the value of performing contrast CT in addition to non-contrast CT in the evaluation of acute non-traumatic central nervous system disorders, we retrospectively reviewed 322 cases originating from the emergency room at our institution. The most common indication for scanning was seizure activity (34% of total), followed by headache (30%), focal neurological deficit (10%), and altered mental status (8%). 75% of the noncontrast scans were normal. The contrast enhanced scan revealed abnormalities not evident on the non-contrast scan in only three of these cases, and the information did not alter patient management. We conclude that in the acute setting, if a non-contrast CT is normal, a contrast study is usually unnecessary. Therefore, given the additional risks of contrast infusion, the contrast study, if needed, is generally best obtained at a later date, after more careful evaluation of the patient's history and medical records. If the non-contrast CT scan is abnormal, a contrast enhanced CT scan may be beneficial, but, again, is often not needed to direct acute patient management. (orig.)

3D Laser Scanning Assisted by Ordinary Plane Mirror for Non-direct Viewing Area

Directory of Open Access Journals (Sweden)

ZHANG Fan

2017-12-01

Full Text Available Terrestrial 3D laser scanning is one of principal methods to get the geometric information of object surface,and the integrity of the scanned object is a basic requirement in data acquisition. In order to solve the missing point cloud problem due to the scanning dead angle caused by confined working space,this paper proposes a method using ordinary plane mirror to obtain laser scanning data for non-direct viewing area according to the plane mirror reflection principle,analyzes the influence mechanism of the ordinary plane mirror on the propagation path and distance of laser beam,deduces the coordinate equation of the object point corresponding to the image point reflected by ordinary plane mirror in laser scanning. Given the laser scanning characteristic,this paper introduces a mirror reflection system included target balls and ordinary plane mirror,and expounds the system construction,system calibration and constructing method of system coordinate system. The feasibility and precision of the method are verified by experiments.

Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques

International Nuclear Information System (INIS)

Zhang Yue-Fei; Wang Li; Wei Bin; Ji Yuan; Han Xiao-Dong; Zhang Ze; Heiderhoff, R.; Geinzer, A. K.; Balk, L. J.

2012-01-01

The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature. The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3ω method. A thermal conductivity of 308 W/m·K within grains corresponding to that of high-purity single crystal AlN is obtained. The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations, as demonstrated in the electron backscattered diffraction. A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites, as indicated by energy dispersive X-ray spectroscopy. (condensed matter: structural, mechanical, and thermal properties)

Bone scan in the diagnosis and management of acute osteoarticular infection in children

International Nuclear Information System (INIS)

Coll, C.; Massardo, T.; Cifras, J.L.; Moya, H.; Verdugo, M.A.; Soza, F.

2002-01-01

Introduction: One of the most important causes of children residual damage in the skeleton in Chile are untreated or treated incompletely osteoarticular infections (OAI). The goal of this study was to assess the value of emergency in-hospital pediatric three-phase bone scan in the evaluation of OAI. Methods: The inclusion criteria were: a) high clinical suspicion of acute OAI and b) a suspect of a secondary localization in a known recent OAI. In this prospective study the gold standard was the final diagnosis at discharge. Thirty-eight children were studied with 54 triphasic bone scans using MDP-Tc99m; some with 4th phase. The population mean age was 4±5 years, 66% of them male. Nine children had their first scan prior to surgical intervention (5 of them had also a posterior follow-up scan) and 17 had a post surgery scan (within a median of 5 days ranging from 1-34 days after surgery). Twelve cases were not submitted to surgery. Results: The global analysis showed 28 cases principally articular and 9 osteomyelitis. The most common germ observed were staphylococcus aureus (37%) and staphylococcus coagulase negative (37%), less common was streptococcus (11%); the hip was affected in 41% of the cases, and less frequently knee and femur. Nine patients with preoperative scans were positive with 16 locations foci. Eighty four % of them were confirmed by surgery/culture (true positive) and surgery was performed within 24 h. There were 3 lesions detected in 2 of the patients with no clinical confirmation (16% false positive). There were not any true negative with surgical confirmation in this group, even though, in 2 clinically suspected sites the bone scan were negative and the patients follow-up was not suggestive of infection in those additional localization. Seven children have negative bone scans (without surgery requirement) that did not present posterior clinical symptomatology in the follow-up up to 3 m. In 5 other cases the vascular phase demonstrated only soft

Can free-viewing perceptual asymmetries be explained by scanning, pre-motor or attentional biases?

Science.gov (United States)

Nicholls, Michael E R; Roberts, Georgina R

2002-04-01

Judgments of relative magnitude between the left and right sides of a stimulus are generally weighted toward the features contained on the left side. This leftward perceptual bias could be the result of, (a) left-to-right scanning biases, (b) pre-motor activation of the right hemisphere, or (c) a left hemispatial attentional bias. The relative merits of these explanations of perceptual asymmetry were investigated. In Experiment 1, English and Hebrew readers made luminance judgements for two left/right mirror-reversed luminance gradients (greyscales task). Despite different reading/scanning habits, both groups exhibited a leftward perceptual bias. English and Hebrew readers also performed a line bisection task. Scanning biases were controlled by asking participants to follow a marker as it moved left-to-right or right-to-left and then stop it as it reached the midpoint of the line. Despite controlling scanning, a leftward bias was observed in both groups. In Experiment 2, peripheral spatial cues were presented prior to the greyscales stimuli. English readers showed a reduction in the leftward bias for right-sided cues as compared to left-sided and neutral cues. Right-side cues presumably overcame a pre-existing leftward attentional bias. In both experiments, pre-motor activation was controlled using bimanual responses. Despite this control, a leftward bias was observed throughout the study. The data support the attentional bias account of leftward perceptual biases over the scanning and pre-motor activation accounts. Whether or not unilateral hemispheric activation provides an adequate account of this attentional bias is discussed.

Vibrating wire for beam profile scanning

Directory of Open Access Journals (Sweden)

S. G. Arutunian

1999-12-01

Full Text Available A method that measures the transverse profile (emittance of the bunch by detecting radiation arising at the scattering of the bunch on scanning wire is widely used. In this work information about bunch scattering is obtained by measuring the oscillation frequency of the tightened scanning wire. In such a way, the system of radiation (or secondary particles extraction and measurement can be removed. The entire unit consists of a compact fork with tightened wire and a scanning system. Normal oscillation frequency of a wire depends on wire tension, its geometric parameters, and, in a second approximation, its elastic characteristics. Normal oscillations are generated by interaction of an alternating current through the wire with magnetic field of a permanent magnet. In this case, it is suggested that the magnetic field of the accelerator (field of dipole magnets or quadrupole magnets be used for excitation of oscillations. The dependence of oscillation frequency on beam scattering is determined by several factors, including changes of wire tension caused by transverse force of the beam and influence of beam self-field. Preliminary calculations show that the influence of wire heating will dominate. We have studied strain gauges on the basis of vibrating wire from various materials (tungsten, beryl bronze, and niobium zirconium alloys. A scheme of normal oscillation generation by alternating current in autogeneration circuit with automatic frequency adjustment was selected. A special method of wire fixation and elimination of transverse degrees of freedom allows us to achieve relative stability better than 10^{-5} during several days at a relative resolution of 10^{-6}. Experimental results and estimates of wire heating of existing scanners show that the wire heats up to a few hundred grades, which is enough for measurements. The usage of wire of micrometer thickness diminishes the problem of wire thermalization speed during the scanning of the bunch.

RBC nuclear scan

Science.gov (United States)

... page: //medlineplus.gov/ency/article/003835.htm RBC nuclear scan To use the sharing features on this page, please enable JavaScript. An RBC nuclear scan uses small amounts of radioactive material to ...

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy. Rev. 1

International Nuclear Information System (INIS)

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.; Schemer-Kohrn, Alan L.; Guzman, Anthony D.; Lavender, Curt A.

2016-01-01

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

Evaluation of CT-scanning of the temporal bone in the diagnosis of ear diseases

International Nuclear Information System (INIS)

Murata, Kiyotaka; Isono, Michio; Nishimae, Tadahide; Tamaki, Katsuhiko; Hosoi, Hiroshi; Ohta, Fumihiko

1983-01-01

CT-scanning of 96 temporal bones was carried out to reveal the extension of cholesteatoma, periossicular drainage, fracture lines, enlarged internal acoustic meatus and anomalies of labyrinthine capsules and ossicles. The clinical aspects of CT-scanning of the temporal bone (CTTB) were as follows: 1) Inner ear anomalies were observed in 17 temporal bones of unilateral deafness, high tone loss from unknown origin and fluctuant hearing loss. CTTB may explain the pathology of deafness from unknown origin. 2) Inner ear anomalies may be classified into more detailed groups than before. 3) The extension of cholesteatoma, localization and size of labyrinthine fistula can be estimated prior to surgery. 4) Cholesteatoma in a mastoidectomy cavity may be detected. 5) The malleus and incus may be visualized, although the stapes can hardly be found. 6) Fracture lines of a temporal bone, destruction of the internal acoustic meatus may be clearly detected. (author)

Measuring the plutonium distribution in fuel elements by the gamma scanning method

International Nuclear Information System (INIS)

Gorobets, A.K.; Leshchenko, Yu.I.; Semenov, A.L.

1982-01-01

An on-line system designed for measuring Pu distribution in the length of fresh fuel elements with vibrocompacted UO 2 -PuO 2 fuel rods by the γ-scanning method is described. An algorithm for measurement result processing and the procedure of determination of calibration parameters necessary for the valid signal separat.ion by means of a two-channel analyzer and for evaluation of the self-absorption effect are considered. The device scanning unit consists of two NaI(Tl) detectors simultaneously detecting γ-radiation from the opposite sides of a measured fuel rod section. The cesium source with Esub(γ)=660 keV is used for fuel scanning. On the base of the analysis of the results obtained when studying the BOR-60 experimental fuel elements with fuel rods of 400 mm long by means of the described device clusion is made that fuel element scanning during 20 min (scanning step is 4 mm, measuring time at each step is 10 s) makes it possible to determine Pu distribution with the error less than +-4% at the confidence probability of 0.68

Level-set segmentation of pulmonary nodules in megavolt electronic portal images using a CT prior

International Nuclear Information System (INIS)

Schildkraut, J. S.; Prosser, N.; Savakis, A.; Gomez, J.; Nazareth, D.; Singh, A. K.; Malhotra, H. K.

2010-01-01

Purpose: Pulmonary nodules present unique problems during radiation treatment due to nodule position uncertainty that is caused by respiration. The radiation field has to be enlarged to account for nodule motion during treatment. The purpose of this work is to provide a method of locating a pulmonary nodule in a megavolt portal image that can be used to reduce the internal target volume (ITV) during radiation therapy. A reduction in the ITV would result in a decrease in radiation toxicity to healthy tissue. Methods: Eight patients with nonsmall cell lung cancer were used in this study. CT scans that include the pulmonary nodule were captured with a GE Healthcare LightSpeed RT 16 scanner. Megavolt portal images were acquired with a Varian Trilogy unit equipped with an AS1000 electronic portal imaging device. The nodule localization method uses grayscale morphological filtering and level-set segmentation with a prior. The treatment-time portion of the algorithm is implemented on a graphical processing unit. Results: The method was retrospectively tested on eight cases that include a total of 151 megavolt portal image frames. The method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases. The treatment phase portion of the method has a subsecond execution time that makes it suitable for near-real-time nodule localization. Conclusions: A method was developed to localize a pulmonary nodule in a megavolt portal image. The method uses the characteristics of the nodule in a prior CT scan to enhance the nodule in the portal image and to identify the nodule region by level-set segmentation. In a retrospective study, the method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases studied.

Non-scanning x-ray fluorescence microscope: application to real time micro-imaging

International Nuclear Information System (INIS)

Sakurai, K.; Eba, H.

2000-01-01

So far, x-ray fluorescence (XRF) micro-imaging has been performed by a 2D positional scan of a sample against a collimated beam. Obtaining information on specific elements in a nondestructive manner is an attractive prospect for many scientific applications. Furthermore, a synchrotron micro-beam can enhance the spatial resolution down to 0.1 μm. However, the total measuring time becomes quite long (a few hours to a half day), since one needs a number of scanning points in order to obtain a high-quality image. It is possible to obtain an x-ray image with 1 M pixels and with 20 μm resolution in a very short time of 20 sec - 3 min using a non-scanning XRF microscope, which is based on completely different concept. In the present report, we discuss the application of this technique to real time micro-imaging. The experiments were carried out at BL-4A, Photon Factory, Tsukuba, Japan. We employed a grazing-incidence arrangement to make primary x-rays illuminate the whole sample surface. We adopted parallel-beam optics and extremely-close-geometry in order to detect x-ray fluorescence with a CCD camera. The selective-excitation capability of tunable monochromatic synchrotron radiation is a feasible method for distinguishing the elements of interest. One can obtain an image of each element by differentiating the images obtained above and below the absorption edges of interest. The growth of metallic dendrites from a solution dropped on a substrate was studied successfully. Several different growth patterns, corresponding to concentration and other conditions for diffusion, were observed as x-ray images. Since the present technique requires only 40 sec for each shot, it is possible to record a growing process through repeated exposures like a movie. The authors would like to thank Prof. A. Iida (Photon Factory) for his valuable comments. (author)

SINGLE TREE DETECTION FROM AIRBORNE LASER SCANNING DATA USING A MARKED POINT PROCESS BASED METHOD

Directory of Open Access Journals (Sweden)

J. Zhang

2013-05-01

Full Text Available Tree detection and reconstruction is of great interest in large-scale city modelling. In this paper, we present a marked point process model to detect single trees from airborne laser scanning (ALS data. We consider single trees in ALS recovered canopy height model (CHM as a realization of point process of circles. Unlike traditional marked point process, we sample the model in a constraint configuration space by making use of image process techniques. A Gibbs energy is defined on the model, containing a data term which judge the fitness of the model with respect to the data, and prior term which incorporate the prior knowledge of object layouts. We search the optimal configuration through a steepest gradient descent algorithm. The presented hybrid framework was test on three forest plots and experiments show the effectiveness of the proposed method.

Analysis of thyroid absorbed dose in cervical CT scan with the use of bismuth shielding

International Nuclear Information System (INIS)

Santos, Fernanda S.; Gómez, Álvaro M.L.; Mourão, Arnaldo P.; Santana, Priscila C.

2017-01-01

The Computed Tomography (CT) has become an important tool to diagnose cancer and to obtain additional information for different clinical questions. Today, it is a very fast, painless and noninvasive test that can be performed high quality images. However, CT scan usually requires a higher radiation exposure dose than a conventional radiography examination. The aim of this study is to determine the dose variation deposited in thyroid and in nearby radiosensitive organs, such as: lenses, pharynx, hypophysis, salivary gland and spinal cord with and without the use of bismuth shielded. A cervical CT scan was performed on anthropomorphic male phantom model Alderson Rando, from the occipital to the first thoracic vertebra, using a GE scanner, Discovery model with 64 channels. Dose measurements have been performed by using radiochromic film strips to register the individual doses in the organs of interest. After the phantom cervical CT scan the radiochromic film strips were processed for obtaining digital images. Digital images were worked to obtain the dose variation profiles for each film. With the data obtained, it was found the organ dose variation. The results show that the thyroid received the highest dose, 40.9 mGy, in the phantom, according to the incidence of the primary X-ray beam. (author)

Analysis of thyroid absorbed dose in cervical CT scan with the use of bismuth shielding

Energy Technology Data Exchange (ETDEWEB)

Santos, Fernanda S.; Gómez, Álvaro M.L.; Mourão, Arnaldo P., E-mail: fernanda.stephaniebh@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Santana, Priscila C. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem

2017-07-01

The Computed Tomography (CT) has become an important tool to diagnose cancer and to obtain additional information for different clinical questions. Today, it is a very fast, painless and noninvasive test that can be performed high quality images. However, CT scan usually requires a higher radiation exposure dose than a conventional radiography examination. The aim of this study is to determine the dose variation deposited in thyroid and in nearby radiosensitive organs, such as: lenses, pharynx, hypophysis, salivary gland and spinal cord with and without the use of bismuth shielded. A cervical CT scan was performed on anthropomorphic male phantom model Alderson Rando, from the occipital to the first thoracic vertebra, using a GE scanner, Discovery model with 64 channels. Dose measurements have been performed by using radiochromic film strips to register the individual doses in the organs of interest. After the phantom cervical CT scan the radiochromic film strips were processed for obtaining digital images. Digital images were worked to obtain the dose variation profiles for each film. With the data obtained, it was found the organ dose variation. The results show that the thyroid received the highest dose, 40.9 mGy, in the phantom, according to the incidence of the primary X-ray beam. (author)

A cone-beam computed tomography triple scan procedure to obtain a three-dimensional augmented virtual skull model appropriate for orthognathic surgery planning.

NARCIS (Netherlands)

Swennen, G.R.J.; Mollemans, W.; Clercq, C. De; Abeloos, J.V.S.; Lamoral, P.; Lippens, F.R.C.; Neyt, N.; Casselman, J.W.; Schutyser, F.A.C.

2009-01-01

The aim of this study was to present a new approach to acquire a three-dimensional virtual skull model appropriate for orthognathic surgery planning without the use of plaster dental models and without deformation of the facial soft-tissue mask. A "triple" cone-beam computed tomography (CBCT) scan

Robust Adaptive Thresholder For Document Scanning Applications

Science.gov (United States)

Hsing, To R.

1982-12-01

In document scanning applications, thresholding is used to obtain binary data from a scanner. However, due to: (1) a wide range of different color backgrounds; (2) density variations of printed text information; and (3) the shading effect caused by the optical systems, the use of adaptive thresholding to enhance the useful information is highly desired. This paper describes a new robust adaptive thresholder for obtaining valid binary images. It is basically a memory type algorithm which can dynamically update the black and white reference level to optimize a local adaptive threshold function. The results of high image quality from different types of simulate test patterns can be obtained by this algorithm. The software algorithm is described and experiment results are present to describe the procedures. Results also show that the techniques described here can be used for real-time signal processing in the varied applications.

Obtaining high purity silica from rice hulls

Directory of Open Access Journals (Sweden)

José da Silva Júnior

2010-01-01

Full Text Available Many routes for extracting silica from rice hulls are based on direct calcining. These methods, though, often produce silica contaminated with inorganic impurities. This work presents the study of a strategy for obtaining silica from rice hulls with a purity level adequate for applications in electronics. The technique is based on two leaching steps, using respectively aqua regia and Piranha solutions, which extract the organic matrix and inorganic impurities. The material was characterized by Fourier-transform infrared spectroscopy (FTIR, powder x-ray diffraction (XRD, x-ray fluorescence (XRF, scanning electron microscopy (SEM, particle size analysis by laser diffraction (LPSA and thermal analysis.

Improving image quality by accounting for changes in water temperature during a photoacoustic tomography scan.

Directory of Open Access Journals (Sweden)

Dominique Van de Sompel

Full Text Available The emerging field of photoacoustic tomography is rapidly evolving with many new system designs and reconstruction algorithms being published. Many systems use water as a coupling medium between the scanned object and the ultrasound transducers. Prior to a scan, the water is heated to body temperature to enable small animal imaging. During the scan, the water heating system of some systems is switched off to minimize the risk of bubble formation, which leads to a gradual decrease in water temperature and hence the speed of sound. In this work, we use a commercially available scanner that follows this procedure, and show that a failure to model intra-scan temperature decreases as small as 1.5°C leads to image artifacts that may be difficult to distinguish from true structures, particularly in complex scenes. We then improve image quality by continuously monitoring the water temperature during the scan and applying variable speed of sound corrections in the image reconstruction algorithm. While upgrading to an air bubble-free heating pump and keeping it running during the scan could also solve the changing temperature problem, we show that a software correction for the temperature changes provides a cost-effective alternative to a hardware upgrade. The efficacy of the software corrections was shown to be consistent across objects of widely varying appearances, namely physical phantoms, ex vivo tissue, and in vivo mouse imaging. To the best of our knowledge, this is the first study to demonstrate the efficacy of modeling temporal variations in the speed of sound during photoacoustic scans, as opposed to spatial variations as focused on by previous studies. Since air bubbles pose a common problem in ultrasonic and photoacoustic imaging systems, our results will be useful to future small animal imaging studies that use scanners with similarly limited heating units.

DepositScan, a Scanning Program to Measure Spray Deposition Distributions

Science.gov (United States)

DepositScan, a scanning program was developed to quickly measure spray deposit distributions on water sensitive papers or Kromekote cards which are widely used for determinations of pesticide spray deposition quality on target areas. The program is installed in a portable computer and works with a ...

Large Scale Scanning Probe Microscope "Making Shear Force Scanning visible."

NARCIS (Netherlands)

Bosma, E.; Offerhaus, Herman L.; van der Veen, Jan T.; van der Veen, J.T.; Segerink, Franciscus B.; Wessel, I.M.

2010-01-01

We describe a demonstration of a scanning probe microscope with shear-force tuning fork feedback. The tuning fork is several centimeters long, and the rigid fiber is replaced by a toothpick. By scaling this demonstration to visible dimensions the accessibility of shear-force scanning and tuning fork

Obtaining hydroxyapatite coatings on titanium by the biomimetic method

International Nuclear Information System (INIS)

Paz, A.; Martin, Y.; Pazos, L. M.; Parodi, M. B.; Ybarra, G. O.; Gonzalez, J. E.

2011-01-01

In this work, a study about the deposition of hydroxyapatite on a titanium substrate employing the biomimetic method is presented. A solution with high content of calcium and phosphorus (SCS) was used. In addition, activation of titanium with hydrogen peroxide and hydrochloric acid and a subsequent heat treatment was performed. The characterization of materials used and the coating obtained was carried out by Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). As a result of the activation processes a hydrated titanium oxide was formed. On the active surface, a coating of hydroxyapatite was obtained after a period of 24 h, which has a thickness of about 2-4 μm. (Author) 21 refs.

Can natural selection encode Bayesian priors?

Science.gov (United States)

Ramírez, Juan Camilo; Marshall, James A R

2017-08-07

The evolutionary success of many organisms depends on their ability to make decisions based on estimates of the state of their environment (e.g., predation risk) from uncertain information. These decision problems have optimal solutions and individuals in nature are expected to evolve the behavioural mechanisms to make decisions as if using the optimal solutions. Bayesian inference is the optimal method to produce estimates from uncertain data, thus natural selection is expected to favour individuals with the behavioural mechanisms to make decisions as if they were computing Bayesian estimates in typically-experienced environments, although this does not necessarily imply that favoured decision-makers do perform Bayesian computations exactly. Each individual should evolve to behave as if updating a prior estimate of the unknown environment variable to a posterior estimate as it collects evidence. The prior estimate represents the decision-maker's default belief regarding the environment variable, i.e., the individual's default 'worldview' of the environment. This default belief has been hypothesised to be shaped by natural selection and represent the environment experienced by the individual's ancestors. We present an evolutionary model to explore how accurately Bayesian prior estimates can be encoded genetically and shaped by natural selection when decision-makers learn from uncertain information. The model simulates the evolution of a population of individuals that are required to estimate the probability of an event. Every individual has a prior estimate of this probability and collects noisy cues from the environment in order to update its prior belief to a Bayesian posterior estimate with the evidence gained. The prior is inherited and passed on to offspring. Fitness increases with the accuracy of the posterior estimates produced. Simulations show that prior estimates become accurate over evolutionary time. In addition to these 'Bayesian' individuals, we also

Combined scanning probe and light scattering characterization of multi-stage self-assembly of targeted liposome-based delivery systems

International Nuclear Information System (INIS)

Farkas, N; Dagata, J A; Yang, C; Rait, A; Pirollo, K F; Chang, E H

2011-01-01

The mean size and size distribution of a targeted nanoparticle delivery system (NDS) strongly influences the intrinsic stability and functionality of this molecular complex, affects its performance as a systemic drug delivery platform and ultimately determines its efficacy toward early detection and treatment of cancer. Since its components undergo significant reorganization during multiple stages of self-assembly, it is essential to monitor the size and stability of the complex throughout the NDS formulation in order to ensure its potency and manufacturability prior to entering clinical trials. This work combines scanning probe microscopy (SPM) and dynamic light scattering (DLS) techniques to obtain quantitative and reliable size measurements of the NDS, and to investigate how variations in the NDS formulation or self-assembly process impact the size, structure and functionality of the complex with various therapeutic and diagnostic agent payloads. These combined SPM and DLS methods, when implemented at an early stage of the NDS formulation, present a potential measurement approach to facilitate drug discovery and development, optimization and quality control during manufacturing of the NDS

Calibration-free quantitative surface topography reconstruction in scanning electron microscopy

NARCIS (Netherlands)

Faber, E.T.; Martinez-Martinez, D.; Mansilla, C.; Ocelik, V.; De Hosson, J. Th. M.

This work presents a new approach to obtain reliable surface topography reconstructions from 2D Scanning Electron Microscopy (SEM) images. In this method a set of images taken at different tilt angles are compared by means of digital image correlation (DlC). It is argued that the strength of the

Pulmonary vein stenosis after RF ablation diagnosed on a V/Q lung scan - a case study

International Nuclear Information System (INIS)

Edwards, Russell G.

2009-01-01

Full text: A 26-year-old female presented to the emergency department with pleuritic chest pain, acute SOB and raised D-dimer. A PE was suspected and a V/Q lung scan was performed. The initial V/Q lung scan displayed normal ventilation images but reduced perfusion throughout the left lung. Further evaluation was required and a CTPA and repeat perfusion scan were performed. After review of these imaging procedures it was discovered the patient had poor opacification of her left upper pulmonary vein compared to the left lower and right pulmonary veins. Further investigation into the patient's medical history revealed she had undergone radiofrequency ablation for atrial fibrillation 12 months prior. This was significant as it is well documented that a delayed complication of radiofrequency ablation is pulmonary vein stenosis. Although it is rare for the stenosis to be severe enough to cause symptomatic complications from this treatment for atrial fibrillation, it is becoming more widely used and therefore cases are becoming more prevalent. The patient subsequently had a stent inserted into her stenosed pulmonary vein with symptomatic relief.

Logarithmic axicon characterized by scanning optical probe system.

Science.gov (United States)

Cao, Zhaolou; Wang, Keyi; Wu, Qinglin

2013-05-15

A scanning optical probe system is proposed to measure a logarithmic axicon (LA) with subwavelength resolution. Multiple plane intensity profiles measured by a fiber probe are interpreted by solving an optimization problem to get the phase retardation function (PRF) of the LA. Experimental results show that this approach can accurately obtain the PRF with which the optical path difference of the generated quasi-nondiffracting beam in the propagation is calculated.

Novel bayes factors that capture expert uncertainty in prior density specification in genetic association studies.

Science.gov (United States)

Spencer, Amy V; Cox, Angela; Lin, Wei-Yu; Easton, Douglas F; Michailidou, Kyriaki; Walters, Kevin

2015-05-01

Bayes factors (BFs) are becoming increasingly important tools in genetic association studies, partly because they provide a natural framework for including prior information. The Wakefield BF (WBF) approximation is easy to calculate and assumes a normal prior on the log odds ratio (logOR) with a mean of zero. However, the prior variance (W) must be specified. Because of the potentially high sensitivity of the WBF to the choice of W, we propose several new BF approximations with logOR ∼N(0,W), but allow W to take a probability distribution rather than a fixed value. We provide several prior distributions for W which lead to BFs that can be calculated easily in freely available software packages. These priors allow a wide range of densities for W and provide considerable flexibility. We examine some properties of the priors and BFs and show how to determine the most appropriate prior based on elicited quantiles of the prior odds ratio (OR). We show by simulation that our novel BFs have superior true-positive rates at low false-positive rates compared to those from both P-value and WBF analyses across a range of sample sizes and ORs. We give an example of utilizing our BFs to fine-map the CASP8 region using genotype data on approximately 46,000 breast cancer case and 43,000 healthy control samples from the Collaborative Oncological Gene-environment Study (COGS) Consortium, and compare the single-nucleotide polymorphism ranks to those obtained using WBFs and P-values from univariate logistic regression. © 2015 The Authors. *Genetic Epidemiology published by Wiley Periodicals, Inc.

Example-driven manifold priors for image deconvolution.

Science.gov (United States)

Ni, Jie; Turaga, Pavan; Patel, Vishal M; Chellappa, Rama

2011-11-01

Image restoration methods that exploit prior information about images to be estimated have been extensively studied, typically using the Bayesian framework. In this paper, we consider the role of prior knowledge of the object class in the form of a patch manifold to address the deconvolution problem. Specifically, we incorporate unlabeled image data of the object class, say natural images, in the form of a patch-manifold prior for the object class. The manifold prior is implicitly estimated from the given unlabeled data. We show how the patch-manifold prior effectively exploits the available sample class data for regularizing the deblurring problem. Furthermore, we derive a generalized cross-validation (GCV) function to automatically determine the regularization parameter at each iteration without explicitly knowing the noise variance. Extensive experiments show that this method performs better than many competitive image deconvolution methods.

Technetium /sup 99m/Tc macroaggregated albumin lung scans. Use in chronic childhood asthma

International Nuclear Information System (INIS)

Hyde, J.S.; Koch, D.F.; Isenberg, P.D.; Werner, P.

1976-01-01

Serial roentgenograms and technetium /sub 99m/Tc macroaggregated albumin lung scans were done simultaneously in 30 bronchodilator-dependent asthmatic children and young adults during both relative remission and attacks of status asthmaticus. When chest roentgenograms showed air trapping and increased peribronchial vascular markings associated with persistent perfusion defects, the children benefited from further laboratory studies and continuous comprehensive therapy. Serial scans provided information about underperfusion that was not discernible either by roentgenograms or by usual blood gas studies. Also, lung scans are easier to obtain in children with long-standing asthma than are detailed pulmonary tests. In our study, technetium /sup 99m/Tc macroaggregated albumin scans showed persistent regional perfusion defects in 20 children with chronic asthma during relative remission and exacerbations

Development of a segmented gamma ray scanning system

International Nuclear Information System (INIS)

Zhu Rongbao; Tan Yajun; Yuan Xiaoxin

1994-01-01

A segmented gamma ray scanning system is developed for the purposes of non-destructive assay of the contents of uranium, plutonium or fission products existing in packed low density or medium density nuclear residuals, scrapes or wastes. The near field three-dimensional model for computing CF(AT) is used for cylindrical sample and container, the system developed consists of a transmission source wheel, a rotatable scanning plate, a beam shutter, and annular shielding body, stepping motors and control system, HPGe detector, nuclear electronics and computer. The full scale scanning of samples, spectrum accumulation and data reduction could be fulfilled automatically according to preset standard procedures. The radioisotopes of 169 Yb and 75 Se and used as the transmission sources for assaying 235 U and potential 239 Pu respectively. The calibration experiments using 1 liter solution sample of 192 Ir and 235 U is performed. The standard deviations were obtained for 192 Ir γ rays of 295 keV, 308 keV and 316 keV are +- 0.41%, +- 0.29% and +-0.42% respectively. The standard divination for 235 U 185 keV γ ray is +- 0.62%

Effect of variable scanning protocolson the pre-implant site evaluation of the mandible in reformatted computed tomography

International Nuclear Information System (INIS)

Kim, Kee Deog; Park, Chang Seo

1999-01-01

To evaluate the effect of variable scanning protocols of computed tomography for evaluation of pre-implant site of the mandible through the comparison of the reformatted cross-sectional images of helical CT scans obtained with various imaging parameters versus those of conventional CT scans. A dry mandible was imaged using conventional nonoverlapped CT scans with 1 mm slice thickness and helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. All helical images were reconstructed at reconstruction interval of 1 mm. DentaScan reformatted images were obtained to allow standardized visualization of cross-sectional images of the mandible. The reformatted images were reviewed and measured separately by 4 dental radiologists. The image qualities of continuity of cortical outline, trabecular bone structure and visibility of the mandibular canal were evaluated and the distance between anatomic structures were measured by 4 dental radiologists. On image qualities of continuity of cortical outline, trabecular bone structure and visibility of the mandibular canal and in horizontal measurement, there was no statistically significant difference among conventional and helical scans with pitches of 1.0, 1.5 and 2.0. In vertical measurement, there was no statistically significant difference among the conventional and all imaging parameters of helical CT scans with pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. The images of helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5 and 2.0 are as good as those of conventional CT scans with 1 mm slice thickness for evaluation of pre-dental implant site of the mandible. Considering the radiation dose and patient comfort, helical CT scans with 1 mm slice thickness and pitch of 2.0 is recommended for evaluation of pre-implant site of the mandible.

Scanning three-dimensional x-ray diffraction microscopy using a high-energy microbeam

International Nuclear Information System (INIS)

Hayashi, Y.; Hirose, Y.; Seno, Y.

2016-01-01

A scanning three-dimensional X-ray diffraction (3DXRD) microscope apparatus with a high-energy microbeam was installed at the BL33XU Toyota beamline at SPring-8. The size of the 50 keV beam focused using Kirkpatrick-Baez mirrors was 1.3 μm wide and 1.6 μm high in full width at half maximum. The scanning 3DXRD method was tested for a cold-rolled carbon steel sheet sample. A three-dimensional orientation map with 37 "3 voxels was obtained.

Scanning three-dimensional x-ray diffraction microscopy using a high-energy microbeam

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Y., E-mail: y-hayashi@mosk.tytlabs.co.jp; Hirose, Y.; Seno, Y. [Toyota Central R& D Toyota Central R& D Labs., Inc., 41-1 Nagakute Aichi 480-1192 Japan (Japan)

2016-07-27

A scanning three-dimensional X-ray diffraction (3DXRD) microscope apparatus with a high-energy microbeam was installed at the BL33XU Toyota beamline at SPring-8. The size of the 50 keV beam focused using Kirkpatrick-Baez mirrors was 1.3 μm wide and 1.6 μm high in full width at half maximum. The scanning 3DXRD method was tested for a cold-rolled carbon steel sheet sample. A three-dimensional orientation map with 37 {sup 3} voxels was obtained.

Scanning of bone metastases

International Nuclear Information System (INIS)

Robillard, J.

1977-01-01

The Centers against cancer of Caen, Angers, Montpellier, Strasbourg and 'the Curie Foundation' have confronted their experience in detection of bone metastases by total body scanning. From the investigation by this procedure, of 1,467 patients with cancer, it results: the confrontation between radio and scanning shows a rate of false positive and false negative identical to the literature ones; the countage scanning allows to reduce the number of false positive; scanning allows to direct bone biopsy and to improve efficiency of histological examination [fr

Accuracy and reliability of linear cephalometric measurements from cone-beam computed tomography scans of a dry human skull.