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Sample records for helicoidal computerized tomography

  1. Computerized tomography calibrator

    NASA Technical Reports Server (NTRS)

    Engel, Herbert P. (Inventor)

    1991-01-01

    A set of interchangeable pieces comprising a computerized tomography calibrator, and a method of use thereof, permits focusing of a computerized tomographic (CT) system. The interchangeable pieces include a plurality of nestable, generally planar mother rings, adapted for the receipt of planar inserts of predetermined sizes, and of predetermined material densities. The inserts further define openings therein for receipt of plural sub-inserts. All pieces are of known sizes and densities, permitting the assembling of different configurations of materials of known sizes and combinations of densities, for calibration (i.e., focusing) of a computerized tomographic system through variation of operating variables thereof. Rather than serving as a phanton, which is intended to be representative of a particular workpiece to be tested, the set of interchangeable pieces permits simple and easy standardized calibration of a CT system. The calibrator and its related method of use further includes use of air or of particular fluids for filling various openings, as part of a selected configuration of the set of pieces.

  2. X-ray computerized tomography

    SciTech Connect

    Wellington, S.L.; Vinegar, H.J.

    1987-08-01

    Computerized tomography (CT) is a new radiological imaging technique that measures density and atomic composition inside opaque objects. A revolutionary advance in medical radiology since 1972, CT has only recently been applied in petrophysics and reservoir engineering. This paper discusses several petrophysical applications, including three-dimensional (3D) measurement of density and porosity; rock mechanics studies; correlation of core logs with well logs; characterization of mud invasion, fractures, and disturbed core; and quantification of complex mineralogies and sand/shale ratios. Reservoir engineering applications presented include fundamental studies of CO/sub 2/ displacement in cores, focussing on viscous fingering, gravity segregation, miscibility, and mobility control.

  3. Calibrator Blocks For Computerized Tomography (CT)

    NASA Technical Reports Server (NTRS)

    Engel, H. Peter

    1990-01-01

    Sets of calibrator blocks developed for use with industrial computerized tomography (CT) systems. Set of blocks (or number of stacked sets of blocks) placed on object table of CT system and scanned in usual way. Blocks include holes of known size, shape, and location. Appearance of holes in output image of CT system used to verify operation of system.

  4. Computerized tomography in evaluation of hepatic neoplasms

    SciTech Connect

    Luna, R.F.; Resende, C.; Tishler, J.M.A.; Aldrete, J.S.; Shin, M.S.; Rubin, E.; Rahn, N.H.

    1984-08-01

    The authors reviewed their experience with computerized tomography (CT) of the abdomen in 212 patients with histologically documented liver neoplasms seen during a 30-month period. The CT findings in cavernous hemangioma and focal nodular hyperplasia were specific, and permitted accurate diagnosis of this lesion before biopsy. The CT appearance of all other lesions was variable. CT is useful in providing an accurate evaluation of the intrahepatic and extrahepatic extent of the neoplasm.

  5. Computerized tomography in acute and chronic pancreatitis

    SciTech Connect

    Kalmar, J.A.; Matthews, C.C.; Bishop, L.A.

    1984-11-01

    Modern imaging techniques have revolutionized the diagnostic evaluation of pancreatitis, primarily demonstrating its complications. Computerized tomography (CT) is a more sensitive method than ultrasonography and pancreatic ductography. A chart review revealed 214 patients at our hospital with a discharge diagnosis of pancreatitis. Sixty patients had CT for evaluation of possible complications. Only five scans were normal. Of 37 cases of acute pancreatitis, 92% demonstrated localized or diffuse enlargement, and 65% showed loss of pancreatic outline. Other frequent findings included thickening of perirenal fascia (49%), ileus (43%), edema of mesentery (35%), and inflammatory exudate (32%). Abscess and pseudocyst were each detected in 8% of cases. In chronic pancreatitis 65% of patients showed localized or diffuse pancreatic enlargement. Atrophy of the gland (30%), calcification (30%), pseudocyst (26%), and dilated pancreatic ducts (17%) were also seen. CT is effective in evaluating pancreatitis and its complications. 14 references, 5 figures, 2 tables.

  6. Mid-America Computerized Ionospheric Tomography Experiment (MACE '93)

    NASA Astrophysics Data System (ADS)

    Kronschnabl, G. R.; Bust, G. S.; Cook, J. A.; Vasicek, C. J.

    1995-01-01

    A computerized ionospheric tomography (CIT) experiment utilizing an array of nine Navy Navigation Satellite System (NNSS) receivers deployed along a north-south line from South Dakota to south Texas (spanning over 2000 km) is currently underway. The Mid-America Computerized Ionospheric Tomography Experiment (MACE '93) began collecting data from three receivers deployed in Texas on June 1, 1993. This "short communiqué" presents preliminary results from the experiment.

  7. Computerized tomography using video recorded fluoroscopic images

    NASA Technical Reports Server (NTRS)

    Kak, A. C.; Jakowatz, C. V., Jr.; Baily, N. A.; Keller, R. A.

    1975-01-01

    A computerized tomographic imaging system is examined which employs video-recorded fluoroscopic images as input data. By hooking the video recorder to a digital computer through a suitable interface, such a system permits very rapid construction of tomograms.

  8. Initial clinical experience with computerized tomography of the body.

    PubMed

    Stephens, D H; Sheedy, P F; Hattery, R R; Hartman, G W

    1976-04-01

    Computerized tomography of the body, now possible with an instrument that can complete a scan rapidly enough to permit patients to suspend respiration, adds an important new dimension to radiologic diagnosis. Cross-sectional antomy is uniquely reconstructed to provide accurate diagnostic information for various disorders throughout the body. PMID:772746

  9. Diffuse nesidioblastosis diagnosed on a Ga-68 DOTATATE positron emission tomography/computerized tomography.

    PubMed

    Arun, Sasikumar; Rai Mittal, Bhagwant; Shukla, Jaya; Bhattacharya, Anish; Kumar, Praveen

    2013-07-01

    The authors describe a 50 days old pre-term infant with persistent hyperinsulinemic hypoglycemia of infancy in whom Ga-68 DOTATATE positron emission tomography/computerized tomography scan showed diffusely increased tracer uptake in the entire pancreas with no abnormal tracer uptake anywhere else in the body, suggestive of a diffuse variant of nesidioblastosis. PMID:24250024

  10. Soft x-ray holographic computerized tomography imaging: experimental research

    NASA Astrophysics Data System (ADS)

    Zhang, Yuxuan; Jiang, Shiping; Zhang, Xinyi

    2003-03-01

    A high-resolution three-dimensional (3D) imaging technology has been developed, which is a combination of x-ray holography and computerized tomography (CT) technology called holographic computerized tomography (HCT). The theory and experimental techniques on biological specimens with the use of synchrotron radiation are discussed. Projections at different angles are reconstructed with the numerical method of in-line holography, and then the reconstructed data with a higher lateral resolution are used to restore the 3D image by the CT technique. With this method, the degradation caused by the diffraction of x rays is canceled, and 3D images with high resolution of micrometer magnitude in both the lateral and the longitudinal directions are obtained.

  11. Computerized Tomography: Its Role in Interstitial Brachytherapy of Pelvic Malignancies

    PubMed Central

    Kumar, P. Pradeep; Taylor, Judith; Jones, E.O.; McAnulty, Bruce

    1986-01-01

    The advantages of computerized tomography (CT) in the treatment planning of external beam radiation therapy have been shown in several studies. The authors extended the use of CT to the interstitial brachytherapy treatment planning of pelvic malignancies. CT was found to be invaluable in localizing pelvic tumors, selecting implant techniques, and checking the accuracy of the implant. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5 PMID:3950985

  12. Computerized tomography and skeletal density of coral skeletons

    NASA Astrophysics Data System (ADS)

    Bosscher, Hemmo

    1993-07-01

    In this paper I describe and discuss the use of medical X-ray computerized tomography (CT) in the study of coral skeletons. CT generates X-ray images along freely chosen sections through the skeleton and offers, as well, the possibility of density measurements based on X-ray attenuation. This method has been applied to measure the skeletal density of the Caribbean reef-building coral Montastrea annularis, from Curaçao, Netherlands Antilles. The observed, non-linear increase of skeletal density with depth can be attributed to decreasing photo-synthetic rates with increasing water depth. A comparison with extension rate measurements shows the inverse relationship between extension rate and skeletal density. CT proves to be aquick and non-destructive method to reveal growth structures (density banding) since it measures skeletal density.

  13. The development of algorithms in electrical impedance computerized tomography.

    PubMed

    Shie, J R; Li, C J; Lin, J T

    2000-01-01

    Electrical Impedance Computerized Tomography (EICT) is an imaging method to reconstruct the impedance distribution inside of domain through the boundary injected current and display the impedance contrast ratio as an image. This paper concentrates on developing two algorithms to enhance the quality of the conductivity image. The two algorithms are "Fine-Mesh Conversion Method" and "Sub-Domain EICT Method". "Fine-Mesh Conversion Method" is a numerical calibration process to find a coarse mesh impedance network that behaves like a fine mesh network in terms of giving similar voltages under the same current excitations. "Sub-Domain EICT" solves a higher resolution EICT with the cost of a lower resolution EICT by combining "Fine-Mesh Conversion Method", and a Fuzzy Logic Inference Systems (FLIS) classifier. PMID:10834231

  14. Dental development of the Taung skull from computerized tomography.

    PubMed

    Conroy, G C; Vannier, M W

    Just over 60 years ago, Dart's description and analysis of the Taung child's skull triggered an intellectual revolution about human origins. Recently, several authors have suggested that one of the most significant hominid-like traits of australopithecines, delayed maturation, may not after all be valid. This is a radical departure from Mann's classic study of australopithecine maturation and palaeodemography based on dental eruption patterns. The resolution of this debate has important implications for the history of the biological and social evolution of the human species. In view of the controversies generated by recent studies, and particularly because the Taung skull is the type specimen of Australopithecus africanus, we have investigated the relevant anatomy of the Taung 'child' using computerized tomography. We conclude that the Taung 'child' shows some important dental maturational affinities with great apes, although as Dart noted, other hominid-like features are clearly present. PMID:3116435

  15. Magnetic resonance imaging and computerized tomography in malignant external otitis

    SciTech Connect

    Gherini, S.G.; Brackmann, D.E.; Bradley, W.G.

    1986-05-01

    In malignant external otitis (MEO), determining the anatomic extent of disease and evaluating the physiologic response to therapy remain a problem. Magnetic resonance imaging (MRI) has recently become available in limited clinical settings. Four patients with MEO were evaluated using MRI, computerized tomography (CT), technetium-99 (Tc-99) bone scanning, and gallium-67 citrate (Ga-67 citrate) scanning. MRI is superior to CT, Tc-99 bone scanning, and Ga-67 citrate scanning in evaluating the anatomic extent of soft tissue changes in MEO. MRI alone cannot be relied upon to determine the physiologic response to therapy. MRI can, however, serve as a valuable guide to the interpretation of Tc-99 bone and Ga-67 citrate scans, and in this respect, MRI is extremely useful in the treatment of MEO.

  16. Null space and resolution in dynamic computerized tomography

    NASA Astrophysics Data System (ADS)

    Hahn, Bernadette N.

    2016-02-01

    One major challenge in computerized tomography is to image objects which change during the data acquisition and hence lead to inconsistent data sets. Motion artefacts in the reconstructions can be reduced by applying specially adapted algorithms which take the dynamic behaviour into account. Within this article, we analyse the achievable resolution in the dynamic setting in case of two-dimensional affine deformations. To this end, we characterize the null space of the operator describing the dynamic case, using its singular value decomposition and a necessary dynamic consistency condition. This shows that independent of any reconstruction method, the specimen’s dynamics results in a loss of resolution compared to the stationary setting. Our theoretical results are illustrated at a numerical example.

  17. The study of compressive sampling in ultrasonic computerized tomography

    NASA Astrophysics Data System (ADS)

    Wang, Wentao; Wang, Chonghe; Bao, Yuequan; Li, Hui

    2015-04-01

    This paper proposes a novel and effective method in the field of Non-Destructive Evaluation (NDE). Traditional ultrasonic computerized tomography (UCT) is a heavy task to detect the damages in the object for the numerous measuring times and the huge cost of manual labor. However, utilizing the method proposed in this paper can effectively overcome this great disadvantage, the essence of the application of Compressive Sampling(CS) in the detection of the object is to selectively choose a small quantity of measuring path in the huge number of total measurements. Due to the sparsity of damages in concrete structure, the usage of CS is available. Firstly, we divide the object entirely into numerous grids in order to image the internal situation of the object respectively. Secondly, a measurement matrix to massively decline the quantity of the measuring time should be computed. Thirdly, the travel time of each path we selected according to the matrix should be acquired, utilizing these travel time by adopting the l1-minimization program can we consequently obtained the slowness of the elements inside the object, thus reconstruct the internal situation of the object clearly and effectively. Furthermore, by applying this method we proposed in this paper into the simulation we can not only determine the damage location but also figure the size of it out. Because of the massive decline of the measuring times and accurate reconstruction, we substantiate CS method applied into the monitoring of concrete structure proves to be a shortcut in the field of NDE.

  18. Vertebral sarcoidosis: demonstration of bone involvement by computerized axial tomography

    SciTech Connect

    Dinerstein, S.L.; Kovarsky, J.

    1984-08-01

    A report is given of a rare case of vertebral sarcoidosis with negative conventional spinal x-ray films, yet with typical cystic lesions of the spine found incidentally during abdominal computerized axial tomography (CAT). The patient was a 28-year-old black man, who was admitted for evaluation of a 1 1/2-year history of diffuse myalgias, intermittent fever to 102 F orally, bilateral hilar adenopathy, and leukopenia. A technetium polyphosphate bone scan revealed diffuse areas of increased uptake over the sternum, entire vertebral column, and pelvis. Conventional x-ray films of the cervical, thoracic, and lumbar spine, and an AP view of the pelvis were all normal. Chest x-ray film revealed only bilateral hilar adenopathy. During the course of an extensive negative evaluation for infection, an abdominal CAT scan was done, showing multiple, small, sclerotic-rimmed cysts at multiple levels of the lower thoracic and lumbar spine. Bone marrow biopsy revealed only changes consistent with anemia of chronic disease. Mediastinal lymph node biopsy revealed noncaseating granulomas. A tentative diagnosis of sarcoidosis was made, and treatment with prednisone, isoniazid and rifampin was begun. Within two weeks of initiation of prednisone therapy, the patient was symptom-free. A repeat technetium polyphosphate bone scan revealed only a small residual area of mildly increased uptake over the upper thoracic vertebrae.

  19. Computerized tomography of the acute left upper quadrant pain.

    PubMed

    Tirkes, Temel; Ballenger, Zachary; Steenburg, Scott D; Altman, Daniel J; Sandrasegaran, Kumaresan

    2016-08-01

    The purpose of this study was to evaluate the clinical utility of computerized tomography (CT) of the abdomen in the emergent setting of left upper quadrant pain. One hundred patients (average age: 45, range: 19-93 years, female: 57 %, male: 43 %) who presented to the emergency department (ED) and underwent CT scanning of abdomen with the given indication of left upper quadrant pain were included in this study. The results from CT examinations were compared to final diagnoses determined by either ED physician or clinician on a follow-up visit. Sensitivity of CT was 69 % (95 %CI: 52-83 %) for 39 patients who eventually were diagnosed with an acute abdominal abnormality. Twenty-seven patients had an acute abnormal finding on abdominal CT that represented the cause of the patient's pain (positive predictive value of 100 %, 95 %CI: 87-100 %). Of the remaining 73 patients with negative CT report, 12 were diagnosed clinically (either in the ED or on follow-up visit to specialist) with a pathology that was undetectable on the CT imaging (negative predictive value of 83 %, 95 %CI: 73-91 %). None of the remaining 61 patients with negative CT were found to have pathology by clinical evaluation (specificity of 100 %, 95 %CI: 94-100 %). CT is a useful examination for patients with acute left upper quadrant pain in the emergency department setting with moderate sensitivity and excellent specificity. PMID:27230731

  20. Infantile Autism and Computerized Tomography Brain-Scan Findings: Specific versus Nonspecific Abnormalities.

    ERIC Educational Resources Information Center

    Balottin, Umberto; And Others

    1989-01-01

    The study of computerized tomography brain-scan findings with 45 autistic and 19 control subjects concluded that autism is nonspecifically associated with brain-scan abnormalities, and that other nonorganic, as well as organic, factors should be taken into account. (Author/DB)

  1. Differentiation of Calcium Oxalate Monohydrate and Calcium Oxalate Dihydrate Stones Using Quantitative Morphological Information from Micro-Computerized and Clinical Computerized Tomography

    PubMed Central

    Duan, Xinhui; Qu, Mingliang; Wang, Jia; Trevathan, James; Vrtiska, Terri; Williams, James C.; Krambeck, Amy; Lieske, John; McCollough, Cynthia

    2014-01-01

    Purpose We differentiated calcium oxalate monohydrate and calcium oxalate dihydrate kidney stones using micro and clinical computerized tomography images. Materials and Methods A total of 22 calcium oxalate monohydrate and 15 calcium oxalate dihydrate human kidney stones were scanned using a commercial micro-computerized tomography scanner with a pixel size of 7 to 23 μm. Under an institutional review board approved protocol, image data on 10 calcium oxalate monohydrate and 9 calcium oxalate dihydrate stones greater than 5 mm were retrieved from a total of 80 patients who underwent clinical dual energy computerized tomography for clinical indications and had stones available for infrared spectroscopic compositional analysis. Micro and clinical computerized tomography images were processed using in-house software, which quantified stone surface morphology with curvature based calculations. A shape index was generated as a quantitative shape metric to differentiate calcium oxalate monohydrate from calcium oxalate dihydrate stones. Statistical tests were used to test the performance of the shape index. Results On micro-computerized tomography images the shape index of calcium oxalate monohydrate and calcium oxalate dihydrate stones significantly differed (ROC curve AUC 0.92, p <0.0001). At the optimal cutoff sensitivity was 0.93 and specificity was 0.91. On clinical computerized tomography images a significant morphological difference was also detected (p = 0.007). AUC, sensitivity and specificity were 0.90, 1 and 0.73, respectively. Conclusions On micro and clinical computerized tomography images a morphological difference was detectable in calcium oxalate monohydrate and calcium oxalate dihydrate stones larger than 5 mm. The shape index is a highly promising method that can distinguish calcium oxalate monohydrate and calcium oxalate dihydrate stones with reasonable accuracy. PMID:23142201

  2. Imaging results of multi-modal ultrasound computerized tomography system designed for breast diagnosis.

    PubMed

    Opieliński, Krzysztof J; Pruchnicki, Piotr; Gudra, Tadeusz; Podgórski, Przemysław; Kurcz, Jacek; Kraśnicki, Tomasz; Sąsiadek, Marek; Majewski, Jarosław

    2015-12-01

    Nowadays, in the era of common computerization, transmission and reflection methods are intensively developed in addition to improving classical ultrasound methods (US) for imaging of tissue structure, in particular ultrasound transmission tomography UTT (analogous to computed tomography CT which uses X-rays) and reflection tomography URT (based on the synthetic aperture method used in radar imaging techniques). This paper presents and analyses the results of ultrasound transmission tomography imaging of the internal structure of the female breast biopsy phantom CIRS Model 052A and the results of the ultrasound reflection tomography imaging of a wire sample. Imaging was performed using a multi-modal ultrasound computerized tomography system developed with the participation of a private investor. The results were compared with the results of imaging obtained using dual energy CT, MR mammography and conventional US method. The obtained results indicate that the developed UTT and URT methods, after the acceleration of the scanning process, thus enabling in vivo examination, may be successfully used for detection and detailed characterization of breast lesions in women. PMID:25759234

  3. The applications of optical computerized tomography (OCT) in cold and hot complex flow fields

    NASA Astrophysics Data System (ADS)

    Chen, Yun-Yun; Chen, Li-zhu; Gu, Fang

    2014-11-01

    Optical computerized tomography (OCT), as a branch of computerized tomography (CT) techniques, has been widely used to display and diagnose a variety of complex flow fields, due to its characteristics of real-time, stable, non-contact and can supply 3-D distributions. In practical applications, we found some different phenomenon when they are adopted in clod and hot complex flow fields. In this paper, the cold and hot flow field's OCT diagnosis is analyzed and compared. The results show that 1) OCT can directly reflect the spatial distribution of the measured flow field's refractive index, for both the cold and the hot complex flow fields; 2) OCT can reflect the boundary or structure of the cold flow fields, but could not well done for the hot flow fields. The involved results will help us to make better use of OCT methods to diagnose various cold or hot complex flow fields.

  4. Dental implants in bilateral bifid canal and compromised interocclusal space using cone beam computerized tomography.

    PubMed

    Ahmed, Nizar; Arunachalam, Lalitha Tanjore; Jacob, Caroline Annette; Kumar, Suresh Anand

    2016-01-01

    Knowledge of various anatomic landmarks is pivotal for important success. Bifid canals pose a challenge and can lead to difficulties while performing implant surgery in the mandible. Bifid canals can be diagnosed with panoramic radiography and more accurately with cone beam computerized tomography (CBCT). This case report details the placement of the implant in a patient with bilateral bifid canal and compromised interocclusal space, which was successfully treated using CBCT. PMID:27433073

  5. Dental implants in bilateral bifid canal and compromised interocclusal space using cone beam computerized tomography

    PubMed Central

    Ahmed, Nizar; Arunachalam, Lalitha Tanjore; Jacob, Caroline Annette; Kumar, Suresh Anand

    2016-01-01

    Knowledge of various anatomic landmarks is pivotal for important success. Bifid canals pose a challenge and can lead to difficulties while performing implant surgery in the mandible. Bifid canals can be diagnosed with panoramic radiography and more accurately with cone beam computerized tomography (CBCT). This case report details the placement of the implant in a patient with bilateral bifid canal and compromised interocclusal space, which was successfully treated using CBCT. PMID:27433073

  6. Extension of the Gladstone-Dale equation for flame flow field diagnosis by optical computerized tomography

    SciTech Connect

    Chen Yunyun; Li Zhenhua; Song Yang; He Anzhi

    2009-05-01

    An extended model of the original Gladstone-Dale (G-D) equation is proposed for optical computerized tomography (OCT) diagnosis of flame flow fields. For the purpose of verifying the newly established model, propane combustion is used as a practical example for experiment, and moire deflection tomography is introduced with the probe wavelength 808 nm. The results indicate that the temperature based on the extended model is more accurate than that based on the original G-D equation. In a word, the extended model can be suitable for all kinds of flame flow fields whatever the components, temperature, and ionization are.

  7. [Diagnosis of para-laryngeal tumors using computerized tomography].

    PubMed

    Höing, R

    1990-04-01

    Computed tomography of the larynx is generally recommended for carcinoma, laryngoceles, and laryngeal trauma. On the basis of several case examples, in which dysphagia and hoarseness were caused by a submucosal thickening of the arytenoid and aryepiglottic fold, the authors propose that these unclear symptoms also be regarded as indication for larynx CT. It must be borne in mind that the underlying process may be one of the rare tumors in the space between the thyroid cartilage and elastic cone, often called the paraglottic space (or paralaryngeal space, by many American authors). PMID:2162176

  8. Evaluation of Biomaterials Using Micro-Computerized Tomography

    NASA Astrophysics Data System (ADS)

    Torris, A. T. Arun; Columbus, K. C. Soumya; Saaj, U. S.; Nair, Manitha B.; Krishnan, Kalliyana V.

    2008-09-01

    Micro-computed tomography or Micro-CT is a high resolution, non-invasive, x-ray scanning technique that allows precise three-dimensional imaging and quantification of micro-architectural and structural parameters of objects. Tomographic reconstruction is based on a cone-beam convolution-back-projection algorithm. Micro-architectural and structural parameters such as porosity, surface area to volume ratio, interconnectivity, pore size, wall thickness, anisotropy and cross-section area of biomaterials and bio-specimens such as trabecular bone, polymer scaffold, bio-ceramics and dental restorative were evaluated through imaging and computer aided manipulation of the object scan data sets.

  9. Evaluation of Biomaterials Using Micro-Computerized Tomography

    SciTech Connect

    Torris, A. T. Arun; Columbus, K. C. Soumya; Saaj, U. S.; Krishnan, Kalliyana V.; Nair, Manitha B.

    2008-09-26

    Micro-computed tomography or Micro-CT is a high resolution, non-invasive, x-ray scanning technique that allows precise three-dimensional imaging and quantification of micro-architectural and structural parameters of objects. Tomographic reconstruction is based on a cone-beam convolution-back-projection algorithm. Micro-architectural and structural parameters such as porosity, surface area to volume ratio, interconnectivity, pore size, wall thickness, anisotropy and cross-section area of biomaterials and bio-specimens such as trabecular bone, polymer scaffold, bio-ceramics and dental restorative were evaluated through imaging and computer aided manipulation of the object scan data sets.

  10. [Densitometric follow-up of algodystrophy using computerized tomography].

    PubMed

    Lindecken, K D; Krawzak, H W; Strosche, H; Kukulies, R; Schmidt, W G

    1987-01-01

    Clinical and radiological findings obtained from diagnosis and follow-up examination of post-traumatic algodystrophy (Morbus Sudeck) are very much open to subjective interpretation. Decisive importance is attributed not only to alteration of soft tissue but also to typical distribution patterns and severity of bone demineralisation. No objectifiable and quantifiable have so far become available for proper assessment but are urgently desirable in view of the great number of therapeutic approaches. Densitometry integrated with computed tomography was applied to nine patients with algodystrophy of hand or foot in the region of spongy bones to determine absorption values which were then compared with those on the clinically intact side. Significant differences between sides proved to be objectifiable and were quantifiable measures by which demineralisation of the effected extremity could be assessed. Repeated examinations were undertaken for follow-up through a period up to nine months. PMID:3630448

  11. Karyotype, Pedigree and cone-beam computerized tomography analysis of a case of nonsyndromic pandental anomalies

    PubMed Central

    Dharmani, Umesh; Jadhav, Ganesh Ranganath; Kaur Dharmani, Charan Kamal; Rajput, Akhil; Mittal, Priya; Abraham, Sathish; Soni, Vinay

    2015-01-01

    This case report presented a karyotype and pedigree analysis of a case with unusual combination of dental anomalies: Generalized short roots, talon cusps, dens invagination, low alveolar bone heights, very prominent cusp of carabelli and protostylid on first permanent molars, taurodontism of second permanent molars, rotated, missing and impacted teeth. None of the anomalies alone are rare. However, until date, nonsyndromic pandental anomalies that are affecting entire dentition with detailed karyotype, pedigree and cone-beam computerized tomography analysis have not been reported. The occurrence of these anomalies is probably incidental as the conditions are etiologically unrelated. PMID:26283856

  12. Detection of drugs and explosives using neutron computerized tomography and artificial intelligence techniques.

    PubMed

    Ferreira, F J O; Crispim, V R; Silva, A X

    2010-06-01

    In this study the development of a methodology to detect illicit drugs and plastic explosives is described with the objective of being applied in the realm of public security. For this end, non-destructive assay with neutrons was used and the technique applied was the real time neutron radiography together with computerized tomography. The system is endowed with automatic responses based upon the application of an artificial intelligence technique. In previous tests using real samples, the system proved capable of identifying 97% of the inspected materials. PMID:20149671

  13. Numerical calculation of the rock permittivity using micro computerized tomography image

    NASA Astrophysics Data System (ADS)

    Guo, Chen; Liu, Richard; Jin, Zhao; He, Zhili

    2014-05-01

    A numerical evaluation of the permittivity of sandstones through the micro computerized tomography (micro CT) images at 1.1 GHz is conducted by using an image porosity extracting algorithm and an improved Finite Difference Method (FDM). Within the acquired physical properties by 3D micro CT scanning, numerical method is used to compute the permittivity of the rock samples. A resonant cavity is used for experimental measurement. The simulated results of 2 clastic sandstone samples with dry state and saturated state are compared with experimental data for validating the accuracy of the proposed numerical method. The results show great agreement and the error of permittivity evaluation is less than 3%.

  14. [Computerized tomography of the organs of the small pelvis in children with anorectal atresia].

    PubMed

    Sitkovskiĭ, N B; Babiĭ, Ia S; Kaplan, V M; Dan'shin, T I; Sil'chenko, M I; Bodnar', V V; Gbenu, A S

    1992-01-01

    In 12 children with the different forms of anorectal atresia, for studying the state of a sphincter apparatus of the rectum and assessment of quality of its bringing down into the perineum after proctoplasty, computerized tomography of the organs of a small pelvis was used. Underdeveloped and undifferentiated musculus levator ani in children with high anorectal atresia and fistula to the urinary bladder was revealed. The method permits to establish exact location of the intestine brought down relative to musculus levator ani and external anal sphincter. PMID:1518247

  15. Non-Conventional Applications of Computerized Tomography: Analysis of Solid Dosage Forms Produced by Pharmaceutical Industry

    SciTech Connect

    Martins de Oliveira, Jose Jr.; Germano Martins, Antonio Cesar

    2010-05-21

    X-ray computed tomography (CT) refers to the cross-sectional imaging of an object measuring the transmitted radiation at different directions. In this work, we describe a non-conventional application of computerized tomography: visualization and improvements in the understanding of some internal structural features of solid dosage forms. A micro-CT X-ray scanner, with a minimum resolution of 30 mum was used to characterize some pharmaceutical tablets, granules, controlled-release osmotic tablet and liquid-filled soft-gelatin capsules. The analysis presented in this work are essentially qualitative, but quantitative parameters, such as porosity, density distribution, tablets dimensions, etc. could also be obtained using the related CT techniques.

  16. An introduction to computerized x-ray tomography for petroleum research

    SciTech Connect

    Castanier, L.M.

    1989-06-01

    This report summarizes the state of the art in the application of medical tomography (CT) to petroleum recovery problems. A brief review of the basic principles of x-ray computerized tomography is followed by a discussion of the governing equations of the method. Calculation techniques and appropriate correlations for continued testing are described and discussed. A review of existing medical software is done. Consideration of the specific software needed for petroleum engineering as well as applications of new technologies such as image processing and computer networking are described. Criteria for the choice of a machine suitable for most petroleum-related applications are given. Emphasis is placed on flexibility, reliability, accuracy and price of the scanner. Two separate sections discuss positioning of the core and design of the core holders. Examples of possible applications of CT scanning to problems of geology, core analysis, EOR as well as operational process problems are discussed. 9 refs., 8 figs., 1 tab.

  17. Non-Conventional Applications of Computerized Tomography: Analysis of Solid Dosage Forms Produced by Pharmaceutical Industry

    NASA Astrophysics Data System (ADS)

    de Oliveira, José Martins; Germano Martins, Antonio César

    2010-05-01

    X-ray computed tomography (CT) refers to the cross-sectional imaging of an object measuring the transmitted radiation at different directions. In this work, we describe a non-conventional application of computerized tomography: visualization and improvements in the understanding of some internal structural features of solid dosage forms. A micro-CT X-ray scanner, with a minimum resolution of 30 μm was used to characterize some pharmaceutical tablets, granules, controlled-release osmotic tablet and liquid-filled soft-gelatin capsules. The analysis presented in this work are essentially qualitative, but quantitative parameters, such as porosity, density distribution, tablets dimensions, etc. could also be obtained using the related CT techniques.

  18. Accuracy of cone-beam computerized tomography in determining the thickness of palatal masticatory mucosa

    PubMed Central

    Gupta, Prabhati; Jan, Suhail Majid; Behal, Roobal; Mir, Reyaz Ahmad; Shafi, Munaza

    2015-01-01

    Background: The palatal masticatory mucosa is the main donor area of soft tissue and connective tissue grafts used for increasing the keratinized mucosa around teeth and implants, covering exposed roots and increasing localized alveolar ridge thickness. The aim of this study was to compare the thickness of the palatal masticatory mucosa as determined on a cone-beam computerized tomography scan versus thickness determined via bone-sounding. Materials and Methods: A total of 20 patients requiring palatal surgery participated. Thickness of the palatal tissue was measured at various points radiographically and clinically. The two techniques were compared to determine the agreement of the two measurement modalities. Results: Statistical analysis determined that there was no significant difference between the two methods. Moreover, the tissue thickness was shown to increase as the distance from the gingival margin increased, and the tissue over the premolars was thicker than the other teeth. Conclusion: Cone-beam computerized tomography can be used as a noninvasive method to accurately and consistently determine the soft tissue thickness of the palatal masticatory mucosa with minimal bias at different locations on the palate. PMID:26392687

  19. Comparison of ultrasonography, computerized tomography, and radionuclide imaging in the diagnosis of acute and chronic cholecystitis

    SciTech Connect

    Matolo, N.M.; Stadalnik, R.C.; McGahan, J.P.

    1982-12-01

    Seventy-five patients with abdominal pain in the right upper quadrant who were subsequently confirmed operatively and histologically to have acute or chronic cholecystitis underwent radionuclide imaging of the biliary tree, ultrasonography, and/or computerized tomography before operation. fifty-eight of the patients had acute cholecystitis and 17 had chronic cholecystitis and cholelithiasis. Analysis of our data indicates that ultrasonography is an accurate and better screening test than cholescintigraphy in the diagnosis of chronic cholecystitis and cholelithiasis, but it is less accurate in the detection of acute cholecystitis. On the other hand, radionuclide imaging is highly sensitive and specific in the early diagnosis of acute cholecystitis, but it is poor in the diagnosis of chronic cholecystitis and cholelithiasis unless the cystic duct is obstructed. CT scanning is more expensive than ultrasonography but may be extremely helpful in problematic cases such as the diagnosis of the cause in biliary obstruction or in imaging of the pancreas.

  20. Comparisons of ionospheric electron density distributions reconstructed by GPS computerized tomography, backscatter ionograms, and vertical ionograms

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Lei, Yong; Li, Bofeng; An, Jiachun; Zhu, Peng; Jiang, Chunhua; Zhao, Zhengyu; Zhang, Yuannong; Ni, Binbin; Wang, Zemin; Zhou, Xuhua

    2015-12-01

    Global Positioning System (GPS) computerized ionosphere tomography (CIT) and ionospheric sky wave ground backscatter radar are both capable of measuring the large-scale, two-dimensional (2-D) distributions of ionospheric electron density (IED). Here we report the spatial and temporal electron density results obtained by GPS CIT and backscatter ionogram (BSI) inversion for three individual experiments. Both the GPS CIT and BSI inversion techniques demonstrate the capability and the consistency of reconstructing large-scale IED distributions. To validate the results, electron density profiles obtained from GPS CIT and BSI inversion are quantitatively compared to the vertical ionosonde data, which clearly manifests that both methods output accurate information of ionopsheric electron density and thereby provide reliable approaches to ionospheric soundings. Our study can improve current understanding of the capability and insufficiency of these two methods on the large-scale IED reconstruction.

  1. Single photon emission computerized tomography in obsessive compulsive disorder: a preliminary study.

    PubMed Central

    Adams, B L; Warneke, L B; McEwan, A J; Fraser, B A

    1993-01-01

    Patterns of cerebral perfusion in patients with obsessive compulsive disorder were evaluated using single photon emission computerized tomography. Eleven patients, who satisfied the DSM-III-R criteria and Research Diagnostic Criteria for the disorder, were evaluated using the distribution of 99m-Tc-HMPAO as a radiotracer. The Yale-Brown Obsessive Compulsive Scale was administered to each patient to assess the severity of their symptoms. The images obtained were evaluated qualitatively and semi-quantitatively by a physician in nuclear medicine who was blind to the patients' diagnoses. Eight of the 11 patients demonstrated asymmetric perfusion of the basal ganglia; the left side showed impaired perfusion in six patients. PMID:8499426

  2. An artificial neural net and error backpropagation to reconstruct single photon emission computerized tomography data.

    PubMed

    Knoll, P; Mirzaei, S; Müllner, A; Leitha, T; Koriska, K; Köhn, H; Neumann, M

    1999-02-01

    At present, algorithms used in nuclear medicine to reconstruct single photon emission computerized tomography (SPECT) data are usually based on one of two principles: filtered backprojection and iterative methods. In this paper a different algorithm, applying an artificial neural network (multilayer perception) and error backpropagation as training method are used to reconstruct transaxial slices from SPECT data. The algorithm was implemented on an Elscint XPERT workstation (i486, 50 MHz), used as a routine digital image processing tool in our departments. Reconstruction time for a 64 x 64 matrix is approximately 45 s/transaxial slice. The algorithm has been validated by a mathematical model and tested on heart and Jaszczak phantoms. Phantom studies and very first clinical results ((111)In octreotide SPECT, 99mTc MDP bone SPECT) show in comparison with filtered backprojection an enhancement in image quality. PMID:10076982

  3. Computerized tomography of pelvic osteomyelitis in patients with spinal cord injuries

    SciTech Connect

    Firooznia, H.; Rafii, M.; Golimbu, C.; Sokolow, J.

    1983-12-01

    Computerized tomography (CT) was performed in 19 patients with spinal cord injury (SCI) who had large pressure sores and in whom other complications were suspected. CT detected the depth, extent, and degree of undermining of the edges of the pressure sores in 19 of 27 lesions. Conventional radiography detected four cases of pelvic osteomyelitis. CT detected eight additional cases of pelvic osteomyelitis, as well as eight clinically unsuspected peripelvic and intrapelvic abscesses. Technetium-99m bone scanning was not very helpful because of localization in chronic proliferative changes of bone and widespread foci of myositis ossificans, as well as in osteomyelitis. Gallium-67 scanning detected only one of six abscesses. It was not very helpful because of confusion of abscess and osteomyelitis with intense soft tissue swelling and cellulitis, which are often associated with pressure sores in patients with chronic SCI. CT was found to be, by far, the modality of choice for detection of pelvic osteomyelitis and abscess in patients with SCI.

  4. Computerized axial tomography of the chest for visualization of ''absent'' pulmonary arteries

    SciTech Connect

    Sondheimer, H.M.; Oliphant, M.; Schneider, B.; Kavey, R.E.W.; Blackman, M.S.; Parker, F.B. Jr.

    1982-05-01

    To expand the search for central pulmonary arteries in six patients with absence of cardiac-pulmonary continuity, computerized axial tomography (CAT) of the chest was performed. The CAT scans were compared with previous arteriograms and pulmonary vein wedge angiograms. Three patients with type IV truncus arteriosus were studied, and none had a central, right or left pulmonary artery on CAT scan. However, two patients with tetralogy of Fallot with pulmonary atresia and a patent ductus arteriosus to the right lung demonstrated the presence of a left pulmonary artery. In addition, one child with truncus arteriosus with ''absent'' left pulmonary artery demonstrated a left pulmonary artery on the CAT scan. The CAT scan may therefore enhance our ability to search for disconnected pulmonary arteries in children with complex cyanotic congenital heart disease.

  5. Compact cold stage for micro-computerized tomography imaging of chilled or frozen samples.

    PubMed

    Hullar, Ted; Paige, David F; Rowland, Douglas J; Anastasio, Cort

    2014-04-01

    High resolution X-ray microCT (computerized tomography) can be used to image a variety of objects, including temperature-sensitive materials. In cases where the sample must be chilled or frozen to maintain sample integrity, either the microCT machine itself must be placed in a refrigerated chamber, or a relatively expensive commercial cold stage must be purchased. We describe here the design and construction of a low-cost custom cold stage suitable for use in a microCT imaging system. Our device uses a boron nitride sample holder, two-stage Peltier cooler, fan-cooled heat sink, and electronic controller to maintain sample temperatures as low as -25 °C ± 0.2 °C for the duration of a tomography acquisition. The design does not require modification to the microCT machine, and is easily installed and removed. Our custom cold stage represents a cost-effective solution for refrigerating CT samples for imaging, and is especially useful for shared equipment or machines unsuitable for cold room use. PMID:24784619

  6. Compact cold stage for micro-computerized tomography imaging of chilled or frozen samples

    SciTech Connect

    Hullar, Ted; Anastasio, Cort; Paige, David F.; Rowland, Douglas J.

    2014-04-15

    High resolution X-ray microCT (computerized tomography) can be used to image a variety of objects, including temperature-sensitive materials. In cases where the sample must be chilled or frozen to maintain sample integrity, either the microCT machine itself must be placed in a refrigerated chamber, or a relatively expensive commercial cold stage must be purchased. We describe here the design and construction of a low-cost custom cold stage suitable for use in a microCT imaging system. Our device uses a boron nitride sample holder, two-stage Peltier cooler, fan-cooled heat sink, and electronic controller to maintain sample temperatures as low as −25 °C ± 0.2 °C for the duration of a tomography acquisition. The design does not require modification to the microCT machine, and is easily installed and removed. Our custom cold stage represents a cost-effective solution for refrigerating CT samples for imaging, and is especially useful for shared equipment or machines unsuitable for cold room use.

  7. Compact cold stage for micro-computerized tomography imaging of chilled or frozen samples

    NASA Astrophysics Data System (ADS)

    Hullar, Ted; Paige, David F.; Rowland, Douglas J.; Anastasio, Cort

    2014-04-01

    High resolution X-ray microCT (computerized tomography) can be used to image a variety of objects, including temperature-sensitive materials. In cases where the sample must be chilled or frozen to maintain sample integrity, either the microCT machine itself must be placed in a refrigerated chamber, or a relatively expensive commercial cold stage must be purchased. We describe here the design and construction of a low-cost custom cold stage suitable for use in a microCT imaging system. Our device uses a boron nitride sample holder, two-stage Peltier cooler, fan-cooled heat sink, and electronic controller to maintain sample temperatures as low as -25 °C ± 0.2 °C for the duration of a tomography acquisition. The design does not require modification to the microCT machine, and is easily installed and removed. Our custom cold stage represents a cost-effective solution for refrigerating CT samples for imaging, and is especially useful for shared equipment or machines unsuitable for cold room use.

  8. Computerized tomography technique for reconstruction of obstructed temperature field in infrared thermography

    NASA Astrophysics Data System (ADS)

    Sham, F. C.; Huang, Y. H.; Liu, L.; Chen, Y. S.; Hung, Y. Y.; Lo, T. Y.

    2010-01-01

    Infrared thermography is a rapid, non-invasive and full-field technique for non-destructive testing and evaluation (NDT&E). With all the achievements on IR instrumentation and image processing techniques attained, it has been extended far beyond simple hot-spot detection and becomes one of the most promising NDT&E techniques in the last decades. It has achieved increasing acceptance in different sectors include medical imaging, manufacturing component fault detection and buildings diagnostic. However, one limitation of IR thermography is that the testing results are greatly affected by object surface emissivity. Surface with various emissivities may lead to difficult discrimination between area of defect and area with different emissivity. Therefore, many studies have been carried out on eliminating emissivity, for example, the time derivative approach, lock-in processing and differential contrast measurements. In these methods, sequence of themo-data/images are recorded and being processed in order to eliminate differences of emissivity. Another problem of IR thermography is that any obstruction may limit stimulations and imaging which leads to the observation of unclear defect image. To solve this problem, this paper proposes an algorithm based on the principle of computerized tomography which permits the reconstruction of unavailable/partially available temperature distribution of the affected area using the measured surrounding temperature field. In the process, a set of imaginary rays are projected from many different directions across the area. For each ray, integration of the temperature derivatives along the ray is equals to the temperature difference between the boundary points intercepted by the ray. Therefore, a set of linear equations can be established by considering the multiple rays. Each equation expresses the unknown temperature derivatives in the affected area in terms of the measured boundary temperature data. Solution of the set of simultaneous

  9. A modified conjugate gradient method based on the Tikhonov system for computerized tomography (CT).

    PubMed

    Wang, Qi; Wang, Huaxiang

    2011-04-01

    During the past few decades, computerized tomography (CT) was widely used for non-destructive testing (NDT) and non-destructive examination (NDE) in the industrial area because of its characteristics of non-invasiveness and visibility. Recently, CT technology has been applied to multi-phase flow measurement. Using the principle of radiation attenuation measurements along different directions through the investigated object with a special reconstruction algorithm, cross-sectional information of the scanned object can be worked out. It is a typical inverse problem and has always been a challenge for its nonlinearity and ill-conditions. The Tikhonov regulation method is widely used for similar ill-posed problems. However, the conventional Tikhonov method does not provide reconstructions with qualities good enough, the relative errors between the reconstructed images and the real distribution should be further reduced. In this paper, a modified conjugate gradient (CG) method is applied to a Tikhonov system (MCGT method) for reconstructing CT images. The computational load is dominated by the number of independent measurements m, and a preconditioner is imported to lower the condition number of the Tikhonov system. Both simulation and experiment results indicate that the proposed method can reduce the computational time and improve the quality of image reconstruction. PMID:21129739

  10. Correlations between computerized tomography of the head and motor developmental disturbances of children with cerebral palsy.

    PubMed

    Chen, Y H

    1981-01-01

    Two hundred and eight-two children with cerebral palsy (C.P.) and thirty-seven normal children were studied by computerized tomography (C.T.) of the head for finding out the correlations between the organic damage of the brain and the motor developmental disturbance. The abnormal findings of C.T. were: enlargement of the ventricular system, high density area, low density area and porencephalus, enlargement of the sulcus and anomaly of the medial structure. Enlargement of the ventricular system seemed to have correlation with spasticity; the portion and the extent of the enlargement corresponded to the affected extremities and the severity of the spasticity. Children of other types also showed various abnormal C.T. findings but, in general, less than that of spastic types. The prognosis of the motor development of C.P. children cannot be predicted by serial C.T. examinations strictly, because early treatment could cause improvement to that of these children. However, it is of worthy notice that C.T. is an effective method of helping to diagnose the motor developmental disturbance in earlier childhood. PMID:6974207

  11. Survey radiography and computerized tomography imaging of the thorax in female dogs with mammary tumors

    PubMed Central

    2010-01-01

    Background Accurate early diagnosis of lung metastases is important for establishing therapeutic measures. Therefore, the present study aimed to compare survey thoracic radiographs and computerized tomography (CT) scans to specifically identify lung metastases in female dogs with mammary tumors. Methods Twenty-one female dogs, weighing 3 to 34 kg and aged from 5 years to 14 years and 10 months, with mammary tumors were studied. In all dogs before the imaging examinations, fine-needle aspiration cytology of the mammary tumors was performed to confirm the diagnosis. Three-view thoracic radiographs were accomplished: right lateral, left lateral and ventrodorsal views. Sequential transverse images of the thorax were acquired on a spiral Scanner, before and after intravenous bolus injection of nonionic iodine contrast. Soft-tissue and lung windows were applied. All the mammary tumors were surgically removed and examined histologically. Results The correlation between the cytological and histological results regarding presence of malignancy was observed in only 17 cases. In radiographic examinations, no dog displayed signs of lung metastases or thorax chest lesions. CT detected lung metastasis in two cases, while small areas of lung atelectasis located peripherally were found in 28.57% of the dogs. Conclusion In this study population, spiral CT showed higher sensitivity than chest radiographies to detect lung metastasis; this indicates that CT should be performed on all female dogs with malignant mammary tumors. PMID:20214816

  12. Numerical Modeling of Jointed Rock Under Compressive Loading Using X-ray Computerized Tomography

    NASA Astrophysics Data System (ADS)

    Yu, Qinglei; Yang, Shengqi; Ranjith, P. G.; Zhu, Wancheng; Yang, Tianhong

    2016-03-01

    As jointed rocks consist of joints embedded within intact rock blocks, the presence and geometrical fabric of joints have a great influence on the mechanical behavior of rock. With consideration of the actual spatial shape of joints, a numerical model is proposed to investigate the fracture evolution mechanism of jointed rocks. In the proposed model, computerized tomography (CT) scanning is first used to capture the microstructure of a jointed sandstone specimen, which is artificially fabricated by loading the intact sample until the residual strength, and then digital image processing (DIP) techniques are applied to characterize the geometrical fabric of joints from the CT images. A simple vectorization method is used to convert the microstructure based on a cross-sectional image into a layer of 3-D vectorized microstructure and the overall 3-D model of the jointed sandstone including the real spatial shape of the joints is established by stacking the layers in a specific sequence. The 3-D model is then integrated into a well-established code [three-dimensional Rock Failure Process Analysis, (RFPA3D)]. Using the proposed model, a uniaxial compression test of the jointed sandstone is simulated. The results show that the presence of joints can produce tensile stress zones surrounding them, which result in the fracture of jointed rocks under a relatively small external load. In addition, the spatial shape of the joints has a great influence on the fracture process of jointed rocks.

  13. [Multislice computerized tomography coronary angiography: general principles, technique and clinical applications].

    PubMed

    Karabulut, Nevzat

    2008-07-01

    Electrocardiogram-gated coronary multislice computerized tomography (CT) angiography is a rapidly improving technology allowing noninvasive imaging of coronary arteries. After the initial promising results obtained with four-section CT scanners, progressively higher temporal and spatial resolutions have been achieved by increasing gantry rotation speed and the number of detector rows and by reducing individual detector size. This review presents an overview of the general principles, technique and emerging applications and artifacts of coronary multislice CT angiography. The diagnostic performance of this new technology allows it to be used to evaluate the presence of coronary plaques and stenosis, coronary bypass graft patency, and the origin and course of congenital coronary anomalies. As it visualizes coronary artery wall in addition to lumen and provides volumetric data of heart and great vessels, it readily demonstrates plaque remodeling, ostial lesions and other cardiac and extracardiac abnormalities. The high negative predictive value of coronary CT angiography makes it a valuable tool in the evaluation of patients with low or intermediate pretest probability for coronary artery disease. However, improvements in spatial and temporal resolution are still needed in the imaging of small coronary stents, in the detection and characterization of noncalcified plaques, and to overcome image degradation by arrhythmias, higher heart rates, and calcium-related artifacts. PMID:18611837

  14. Noise reduction in ultrasonic computerized tomography by preprocessing for projection data

    NASA Astrophysics Data System (ADS)

    Norose, Yoko; Mizutani, Koichi; Wakatsuki, Naoto; Ebihara, Tadashi

    2015-07-01

    In this study, an ultrasonic computerized tomography (CT) using time-of-flights (TOFs) has been used for the nondestructive inspection of steel billets with high acoustic attenuation. One of the remaining problems of this method is noise in CT images, which makes it difficult to distinguish defects from noise. Conventionally, noise is suppressed by a low-pass filter (LPF) in the process of filtered back projection (FBP). However, it has been found that there is residual noise even after filtering. To cope with this problem, in this study, the noise observed in ultrasonic testing was examined. As a result, it was found that the TOF data used for CT processing contains impulse noise, which remains in the CT image even after filtering, owing to the existence of transducer directivity. To remove impulse noise selectively, we propose a noise reduction technique for ultrasonic CT for steel billet inspection, that is, preprocessing (outlier detection and removal) of TOF data. The performance of the proposed technique was evaluated experimentally. The obtained results suggest that the proposed technique can remove impulse noise selectively and markedly improve the quality of the CT image. Hence, the proposed technique can improve the performance of ultrasonic CT for steel billet inspection.

  15. Processing of projections containing phase contrast in laboratory micro-computerized tomography imaging

    PubMed Central

    Zápražný, Zdenko; Korytár, Dušan; Mikulík, Petr; Áč, Vladimír

    2013-01-01

    Free-space-propagation-based imaging belongs to several techniques for achieving phase contrast in the hard X-ray range. The basic precondition is to use an X-ray beam with a high degree of coherence. Although the best sources of coherent X-rays are synchrotrons, spatially coherent X-rays emitted from a sufficiently small spot of laboratory microfocus or sub-microfocus sources allow the transfer of some of the modern imaging techniques from synchrotrons to laboratories. Spatially coherent X-rays traverse a sample leading to a phase shift. Beam deflection induced by the local change of refractive index may be expressed as a dark–bright contrast on the edges of the object in an X-ray projection. This phenomenon of edge enhancement leads to an increase in spatial resolution of X-ray projections but may also lead to unpleasant artefacts in computerized tomography unless phase and absorption contributions are separated. The possibilities of processing X-ray images of lightweight objects containing phase contrast using phase-retrieval methods in laboratory conditions are tested and the results obtained are presented. For this purpose, simulated and recorded X-ray projections taken from a laboratory imaging system with a microfocus X-ray source and a high-resolution CCD camera were processed and a qualitative comparison of results was made. PMID:24046501

  16. Computerized Tomography Scanning and Magnetic Resonance Imaging Will Terminate the Era of the Autopsy - A Hypothesis

    PubMed Central

    Benharroch, Daniel; Shvarts, Shifra; Jotkowitz, Alan; Shelef, Ilan

    2016-01-01

    Background: Reports on a marked reduction of the number of autopsies performed worldwide to less than 5% of hospital deaths remain without a satisfactory explanation. The premature disappearance of the autopsy might represent a medical tragedy of a major order. One of the causes for the decrease in autopsies is poorly documented: we suspect that the attending physician might show some reluctance when requesting a consent for an autopsy from the bereaved family. Moreover, this officer might consider that the post mortem will add little information to that already obtained from the computerized tomography scanner or the magnetic resonance imaging. Methods: In order to confirm our hypothesis, we carried out a review of 300 articles indexed as "radiologic-histologic correlation", 118 of which were selected for a significant correlation. From the abstracts, we retrieved the type of the article, the degree of correlation as assessed by the authors and the form of imaging employed, and we computed them. Results & conclusions: The most striking correlation was observed in the small prospective series. An additional search for the "radiologic-autopsy correlation" supported a marked reduction in the number of post-mortems, especially those related with prospective studies. Based on the present study, we cannot determine precisely the role of the house officer in this tragedy. We may have demonstrated, however, that the modern radiologic methods have not yet reached a high enough performance quality to achieve the status of a candidate substitute for the autopsy. PMID:26722367

  17. An interesting case of polyostotic fibrous dysplasia: The "pirate sign" evaluated with Tc-99m methylene diphosphonate single-photon emission computed tomography/computerized tomography.

    PubMed

    Harisankar, Chidambaram Natarajan Balasubramanian; Bhattacharya, Anish; Bhadada, Sanjay Kumar; Kamaleshwaran, Koramadai Karuppusamy; Mittal, Bhagwant Rai

    2011-01-01

    Polyostotic fibrous dysplasia is a rare progressive benign disorder of the bone. Bone scintigraphy is extremely useful in the initial evaluation for identifying the extent of disease. We report a case presenting with pathological fracture of the shaft of the right femur. After treatment of the fracture, bone scintigraphy revealed involvement of multiple bones including the skull and facial bones. The utility of single-photon emission computed tomography/computerized tomography in the evaluation of the extent of skull base involvement is highlighted. PMID:21969780

  18. Assessment of the Anterior Loop of the Mental Nerve Using Cone Beam Computerized Tomography Scan.

    PubMed

    Lu, Chun-I; Won, John; Al-Ardah, Aladdin; Santana, Ruben; Rice, Dwight; Lozada, Jaime

    2015-12-01

    The purpose of this study is to use cone-beam computerized tomography (CBCT) scans with oblique-transverse reconstruction modality to measure and compare the anterior loop length (AnLL) of the mental nerve between gender and age groups and to compare the difference between the right and left sides. Sixty-one female and 61 male CBCT scans were randomly selected for each age group: 21-40, 41-60, and 61-80 years. Both right- and left-side AnLLs were measured in each subject using i-CATVision software to measure AnLLs on the oblique transverse plane using multiplanar reconstruction. The anterior loop was identified in 85.2% of cases, with the mean AnLL of the 366 subjects (732 hemimandibles) being 1.46 ± 1.25 mm with no statistically significant difference between right and left sides or between different gender groups. However, the mean AnLL in the 21-40 year group (1.89 ± 1.35 mm) was larger than the AnLL in the 41-60 year group (1.35 ± 1.19 mm) and the 61-80 year group (1.13 ± 1.08 mm). In conclusion, when placing implants in close proximity to mental foramina, caution is recommended to avoid injury to the inferior alveolar nerve. No fixed distance anteriorly from the mental foramen should be considered safe. Using CBCT scans with the oblique-transverse method to accurately identify and measure the AnLL is of utmost importance in avoiding and protecting its integrity. PMID:24552176

  19. A computerized tomography study of the morphological interrelationship between the temporal bones and the craniofacial complex

    PubMed Central

    Costa, Helder Nunes; Slavicek, Rudolf; Sato, Sadao

    2012-01-01

    The hypothesis that the temporal bones are at the center of the dynamics of the craniofacial complex, directly influencing facial morphology, has been put forward long ago. This study examines the role of the spatial positioning of temporal bones (frontal and sagittal inclination) in terms of influencing overall facial morphology. Several 3D linear, angular and orthogonal measurements obtained through computerized analysis of virtual models of 163 modern human skulls reconstructed from cone-beam computed tomography images were analyzed and correlated. Additionally, the sample was divided into two subgroups based on the median value of temporal bone sagittal inclination [anterior rotation group (n = 82); posterior rotation group (n = 81)], and differences between groups evaluated. Correlation coefficients showed that sagittal inclination of the temporal bone was significantly (P < 0.01) related to midline flexion, transversal width and anterior–posterior length of the basicranium, to the anterior–posterior positioning of the mandible and maxilla, and posterior midfacial height. Frontal inclination of the temporal bone was significantly related (P < 0.01) to basicranium anterior–posterior and transversal dimensions, and to posterior midfacial height. In comparison with the posterior rotation group, the anterior rotation group presented a less flexed and anterior–posteriorly longer cranial base, a narrower skull, porion and the articular eminence located more superiorly and posteriorly, a shorter posterior midfacial height, the palatal plane rotated clockwise, a more retrognathic maxilla and mandible, and the upper posterior occlusal plane more inclined and posteriorly located. The results suggest that differences in craniofacial morphology are highly integrated with differences in the positional relationship of the temporal bones. The sagittal inclination of the temporal bone seems to have a greater impact on the 3D morphology of the craniofacial complex than

  20. Characterizing analogue caldera collapse with computerized X-ray micro-tomography

    NASA Astrophysics Data System (ADS)

    Poppe, Sam; Holohan, Eoghan; Boone, Matthieu; Pauwels, Elin; Cnudde, Veerle; Kervyn, Matthieu

    2013-04-01

    Analogue models in the past mainly explored caldera collapse structures by documenting 2D model cross-sections. Kinematic aspects and 3D structures of caldera collapse are less well understood, although they are essential to interpret recent field and monitoring data. We applied high resolution radiography and computerized X-ray micro-tomography (µCT) to image the deformation during analogue fluid withdrawal in small-scale caldera collapse models. The models test and highlight the possibilities and limitations of µCT-scanning to qualitatively image and quantitatively analyse deformation of analogue volcano-tectonic experiments. High resolution interval radiography sequences document '2.5D' surface and internal model geometry, and subsidence kinematics of a collapsing caldera block into an emptying fluid body in an unprecedented way. During the whole drainage process, all subsidence was bound by caldera ring faults. Subsidence was associated with dilatation of the analogue granular material within the collapsing column. The temporal subsidence rate pattern within the subsiding volume comprised three phases: 1) Upward ring fault propagation, 2) Rapid subsidence with the highest subsidence rates within the uppermost subsiding volume, 3) Relatively slower subsidence rates over the whole column with intermittent subsidence rate acceleration. Such acceleration did almost never affect the whole column. By using radiography sequences it is possible in a non-destructive manner to obtain a continuous observation of fault propagation, down sag mechanisms and the subsequent development of collapse structures. Multi-angle µCT scans of the collapse result allow for a full virtual 3D reconstruction of the model. This leads to an unprecedented 3D view on fault geometries. The developed method is a step towards the quantitative documentation of volcano-tectonic models that would render data interpretations immediately comparable to monitoring data available from recent

  1. Use of microfocus computerized tomography as a new technique for characterizing bone tissue around oral implants.

    PubMed

    Van Oossterwyck, H; Duyck, J; Vander Sloten, J; Van der Perre, G; Jansen, J; Wevers, M; Naert, I

    2000-01-01

    Qualitative and quantitative analysis of peri-implant tissues around retrieved oral implants is typically done by means of light microscopy on thin histological sections containing the metal surface and the undecalcified bone. It remains, however, a labor-intensive and thus time-consuming job. Moreover, it is a destructive technique that allows tissue quantification in only a limited number of two-dimensional sections. As an alternative, we evaluated the bone structure around screw-shaped titanium implants by means of microfocus computerized tomography (micro-CT) because it presents a number of advantages compared to conventional sectioning techniques: micro-CT is nondestructive, fast, and allows a fully three-dimensional characterization of the bone structure around the implant. Images can be reconstructed in an arbitrary plane, and three-dimensional reconstructions are also possible. Because of its high resolution, individual trabeculae can be visualized. The accuracy of micro-CT was qualitatively evaluated by comparing histological sections with the corresponding CT slices for the same specimen. The overall trabecular structure is very similar according to both techniques. Even very close to the interface, the titanium implant does not seem to produce significant artifacts. Furthermore, because the complete digital data on the trabecular bone structure around the implant is available, it is possible to create finite-element models of the bone-implant system that model the trabeculae in detail so that mechanical stress transfer at the interface can be studied at the level of individual trabeculae. Therefore, micro-CT seems to be very promising for the in vitro assessment of the three-dimensional bone structure around oral implants. Further research will be needed to evaluate its accuracy in a more quantitative way. PMID:11831302

  2. Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

    PubMed Central

    Kamburoğlu, Kıvanç; Tatar, İlkan; Arıkan, Volkan; Çelik, Hakan Hamdi; Yüksel, Selcen; Özen, Tuncer

    2015-01-01

    Purpose This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. Results The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth. PMID:26730367

  3. Using computerized tomography to determine ionospheric structures. Part 1, Notivation and basic approaches

    SciTech Connect

    Vittitoe, C.N.

    1993-08-01

    Properties of the ionosphere are reviewed along with its correlations with other geophysical phenomena and with applications of ionospheric studies to communication, navigation, and surveillance systems. Computer tomography is identified as a method to determine the detailed, three-dimensional distribution of electron density within the ionosphere. Several tomography methods are described, with a basic approach illustrated by an example. Limitations are identified.

  4. Evaluation of the accuracy of Cone Beam Computerized Tomography (CBCT): medical imaging technology in head and neck reconstruction

    PubMed Central

    2013-01-01

    Background With the introduction, development and commercialization of Cone Beam Computerized Tomography (CBCT) technologies in the field of head and neck reconstruction, clinicians now have increased access to the technology. Given the growth of this new user group, there is an increasing concern regarding proper use, understanding, quality and patient safety. Methods The present study was carried out to evaluate data acquisition of CBCT medical imaging technology and the accuracy of the scanning at three different machine warming times. The study also compared the accuracy of CBCT at 0.2 mm slice thickness and Computerized Tomography (CT) at 1 mm slice thickness. A control model was CT scanned at five random intervals, at 1 mm slice thickness and CBCT scanned at specialized intervals, at 0.2 mm slice thickness. The data was then converted and imported into a software program where a digital registration procedure was used to compare the average deviations of the scanned models to the control. Results The study found that there was no statistically significant difference amongst the three CBCT machine warming times. There was a statistically significant difference between CT scanning with 1 mm slice thickness and CBCT scanning with 0.2 mm slice thickness. Conclusions The accuracy of the i-CAT CBCT scans used in the present study with a parameter at voxel size 0.2, will remain consistent and reliable at any warming stage. Also the difference between the CBCT i-CAT scans and the CT scans was not clinically significant based on suggested requirements of clinicians in head and neck reconstruction. PMID:23672880

  5. A new mapping technique for conversion of slant TEC to vertical TEC based on Computerized Ionospheric Tomography

    NASA Astrophysics Data System (ADS)

    Bhuyan, Pradip; Bhuyan, Pradip; Bhuyan, Kalyan

    The most frequently used mapping function for converting slant TEC to vertical TEC uses a single layer model with the assumption that all free electrons are concentrated in an infinitesimally thick spherical shell at the mean ionospheric height and containing the ionospheric pierce point. Spatial structures present in the ionosphere are not taken into account in such single layer models. A three dimensional mapping algorithm developed by Mannucci et al. (1999) uses three independent constant density slabs stacked vertically to model the electron density with the result of reduction in a level error of the TEC maps. We describe a new approach based on Computerized Ionospheric Tomography (CIT) to convert STEC to VTEC. The new method is independent of any assumption regarding the electron density distribution of the ionosphere. In this method, the ionosphere region of interest is divided in to pixels and TEC is represented as the sum of the integration of empirical functions within the pixels, which are intersected by the path along which TEC is measured. Using a suitable inversion algorithm, the empirical function within each pixel is retrieved from TEC data recorded simultaneously at a meridional chain of GPS receivers. The VTEC values are then easily obtained as the sum of the integration of the empirical functions within each pixel along a vertical path. The CIT method is applied for converting STEC to VTEC using GPS TEC data collected at 12 locations across India since 2003. The stations are aligned along three meridional chains. The vertical TEC values obtained from the CIT method are then compared to VTEC obtained from a single layer model. Results have shown that the CIT can be suitably adapted as a mapping technique, which takes into account the presence of spatial structures in the ionosphere. Keywords: Ionosphere (Indian equatorial and low latitude ionosphere, Vertical Total Electron Content, mapping functions, computerized ionospheric tomography)

  6. A convenient fabrication method of glass helicoid

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-Xia; Luo, Wen-Feng; Wang, Hong-ying; Yang, Sen-lin; Zhang, Xiang-Wu; Li, Yuan-Yuan

    2013-09-01

    In this paper, we present a new and simple method to produce larger height (with millimeter-sized) helical surface compared with the other methods. During the process, a convenient method for the fabrication of the helical substrate made of B270 glass by using a smart oven is presented. A Global 7107 Coordinate Measuring Machines (CMM) is used for the detection of the glass helicoid. The experimental results proved to be in agreement with the theoretical prediction within the uncertainty of the error and can satisfied our requirement. Moreover, this method seems easy and simple to produce larger height helical surface compared with other ways mentioned in the literature.

  7. Hodgkin lymphoma patients in first remission: routine positron emission tomography/computerized tomography imaging is not superior to clinical follow-up for patients with no residual mass.

    PubMed

    Dann, Eldad J; Berkahn, Leanne; Mashiach, Tatiana; Frumer, Michael; Agur, Ariel; McDiarmid, Bridgett; Bar-Shalom, Rachel; Paltiel, Ora; Goldschmidt, Neta

    2014-03-01

    There is no consensus regarding optimal follow-up mode for Hodgkin lymphoma (HL) patients that achieve complete remission following chemotherapy or combined chemo- and radiation therapy. Several studies demonstrated high sensitivity of positron emission tomography/computerized tomography (PET/CT) in detecting disease progression; however, these techniques are currently not recommended for routine follow-up. This retrospective study conducted in two Israeli (N = 291) and one New Zealand academic centres (N = 77), compared a group of HL patients, followed-up with routine imaging every 6 months during the first 2 years after achieving remission, once in the third year, with additional dedicated studies performed due to symptoms or physical findings (Group I) to a group of patients without residual masses who underwent clinically-based surveillance with dedicated imaging upon relapse suspicion (Group II). Five-year overall survival (OS) was 94% and median time to relapse was 8·6 months for both modes. Relapse rates in Groups I and II were 13% and 9%, respectively. During the first 3 years of follow-up, 47·5 and 4·7 studies were performed per detected relapse in Groups I and II, respectively. The current study demonstrated no benefit in either progression-free survival (PFS) or OS in HL patients followed by routine imaging versus clinical follow-up. The cost was 10 times higher for routine imaging. PMID:24313286

  8. Computerized X-ray reconstruction tomography in stereometric analysis of cardiovascular dynamics

    NASA Technical Reports Server (NTRS)

    Robb, R. A.; Harris, L. D.; Ritman, E. L.

    1977-01-01

    A computerized technique is proposed for obtaining cross-sectional images of the dynamic spatial distribution of X-ray attenuation covering the entire anatomic extent of the thorax and its contents in living dogs with a resolution of 1 mm and at time intervals of 1/60 sec. Use is made of an X-ray imaging chain which is a new high-performance video-fluoroscopic system, unique in its design and construction and called SSDSR for single source dynamic spatial reconstructor. This dynamic spatial reconstruction system is shown to provide the temporally and spatially coherent multiple cross sections required to obtain the full three-dimensional anatomic and simultaneous hemodynamic information necessary for detailed quantitative analyses of regional cardiopulmonary and vascular functions in both basic investigations of animals and clinical diagnostic applications to patients. Numerous photographs supplement the text.

  9. A novel three-dimensional image reconstruction method for near-field coded aperture single photon emission computerized tomography

    PubMed Central

    Mu, Zhiping; Hong, Baoming; Li, Shimin; Liu, Yi-Hwa

    2009-01-01

    Coded aperture imaging for two-dimensional (2D) planar objects has been investigated extensively in the past, whereas little success has been achieved in imaging 3D objects using this technique. In this article, the authors present a novel method of 3D single photon emission computerized tomography (SPECT) reconstruction for near-field coded aperture imaging. Multiangular coded aperture projections are acquired and a stack of 2D images is reconstructed separately from each of the projections. Secondary projections are subsequently generated from the reconstructed image stacks based on the geometry of parallel-hole collimation and the variable magnification of near-field coded aperture imaging. Sinograms of cross-sectional slices of 3D objects are assembled from the secondary projections, and the ordered subset expectation and maximization algorithm is employed to reconstruct the cross-sectional image slices from the sinograms. Experiments were conducted using a customized capillary tube phantom and a micro hot rod phantom. Imaged at approximately 50 cm from the detector, hot rods in the phantom with diameters as small as 2.4 mm could be discerned in the reconstructed SPECT images. These results have demonstrated the feasibility of the authors’ 3D coded aperture image reconstruction algorithm for SPECT, representing an important step in their effort to develop a high sensitivity and high resolution SPECT imaging system. PMID:19544769

  10. An assessment of computerized tomography parameters in spinal bone mineralization determination

    SciTech Connect

    Davis, J.S.

    1988-01-01

    This research investigates the effects of changes in clinical parameters on measured bone density values using Quantitative Computed Tomography (QCT). These parameters include changes in patient size, geometry, internal anatomic conditions such as aortic calcifications and bowel gas, gantry slice position and angulation, spin-water bolus air gap distance, and field uniformity effects. It also assesses the reproducibility of the QCT technique on the G.E. 9800 CT scanner as well as the dose to radiosensitive tissues. The CIRS torso phantom was used in each of three size configurations to assess size effects. Mean bone mineral density (BMD) did not significantly vary with phantom size. Variations in patient cross-sectional geometry at constant volume were assessed using a custom manufactured body phantom.

  11. Computerized tomography technique for reconstruction of obstructed phase data in shearography.

    PubMed

    Hung, Y Y; Huang, Y H; Liu, L; Ng, S P; Chen, Y S

    2008-06-10

    Shearography is an interferometric method that overcomes several limitations of holography by eliminating the reference beam. It greatly simplifies the optical setup and has much higher tolerance to environmental disturbances. Consequently, the technique has received considerable industrial acceptance, particularly for nondestructive testing. Shearography, however, is generally not applicable to the measurement of an obstructed area, as the area to be measured must be accessible to both illumination and imaging. We present an algorithm based on the principle of tomography that permits the reconstruction of the unavailable phase distribution in an obstructed area from the measured boundary phase distribution. In the process, a set of imaginary rays is projected from many different directions across the area. For each ray, integration of the phase directional derivative along the ray is equal to the phase difference between the boundary points intercepted by the ray. Therefore, a set of linear equations can be established by considering the multiple rays. Each equation expresses the unknown phase derivatives in the obstructed area in terms of the measured boundary phase. Solution of the set of simultaneous equations yields the unknown phase distribution in the blind area. While its applications to shearography are demonstrated, the technique is potentially applicable to all full-field optical measurement techniques such as holography, speckle interferometry, classical interferometry, thermography, moiré, photoelasticity, and speckle correlation techniques. PMID:18545289

  12. Regional model-based computerized ionospheric tomography using GPS measurements: IONOLAB-CIT

    NASA Astrophysics Data System (ADS)

    Tuna, Hakan; Arikan, Orhan; Arikan, Feza

    2015-10-01

    Three-dimensional imaging of the electron density distribution in the ionosphere is a crucial task for investigating the ionospheric effects. Dual-frequency Global Positioning System (GPS) satellite signals can be used to estimate the slant total electron content (STEC) along the propagation path between a GPS satellite and ground-based receiver station. However, the estimated GPS-STEC is very sparse and highly nonuniformly distributed for obtaining reliable 3-D electron density distributions derived from the measurements alone. Standard tomographic reconstruction techniques are not accurate or reliable enough to represent the full complexity of variable ionosphere. On the other hand, model-based electron density distributions are produced according to the general trends of ionosphere, and these distributions do not agree with measurements, especially for geomagnetically active hours. In this study, a regional 3-D electron density distribution reconstruction method, namely, IONOLAB-CIT, is proposed to assimilate GPS-STEC into physical ionospheric models. The proposed method is based on an iterative optimization framework that tracks the deviations from the ionospheric model in terms of F2 layer critical frequency and maximum ionization height resulting from the comparison of International Reference Ionosphere extended to Plasmasphere (IRI-Plas) model-generated STEC and GPS-STEC. The suggested tomography algorithm is applied successfully for the reconstruction of electron density profiles over Turkey, during quiet and disturbed hours of ionosphere using Turkish National Permanent GPS Network.

  13. The development and role of megavoltage cone beam computerized tomography in radiation oncology

    NASA Astrophysics Data System (ADS)

    Morin, Olivier

    External beam radiation therapy has now the ability to deliver doses that conform tightly to a tumor volume. The steep dose gradients planned in these treatments make it increasingly important to reproduce the patient position and anatomy at each treatment fraction. For this reason, considerable research now focuses on in-room three-dimensional imaging. This thesis describes the first clinical megavoltage cone beam computed tomography (MVCBCT) system, which utilizes a conventional linear accelerator equipped with an amorphous silicon flat panel detector. The document covers the system development and investigation of its clinical applications over the last 4-5 years. The physical performance of the system was evaluated and optimized for soft-tissue contrast resolution leading to recommendations of imaging protocols to use for specific clinical applications and body sites. MVCBCT images can resolve differences of 5% in electron density for a mean dose of 9 cGy. Hence, the image quality of this system is sufficient to differentiate some soft-tissue structures. The absolute positioning accuracy with MVCBCT is better than 1 mm. The accuracy of isodose lines calculated using MVCBCT images of head and neck patients is within 3% and 3 mm. The system shows excellent stability in image quality, CT# calibration, radiation exposure and absolute positioning over a period of 8 months. A procedure for MVCBCT quality assurance was developed. In our clinic, MVCBCT has been used to detect non rigid spinal cord distortions, to position a patient with a paraspinous tumor close to metallic hardware, to position prostate cancer patients using gold markers or soft-tissue landmarks, to monitor head and neck anatomical changes and their dosimetric consequences, and to complement the convention CT for treatment planning in presence of metallic implants. MVCBCT imaging is changing the clinical practice of our department by increasingly revealing patient-specific errors. New verification

  14. Interfraction Prostate Rotation Determined from In-Room Computerized Tomography Images

    SciTech Connect

    Owen, Rebecca; Kron, Tomas; Foroudi, Farshad; Milner, Alvin; Cox, Jennifer; Duchesne, Gillian

    2011-07-01

    Fiducial markers (FMs) are commonly used as a correction technique for interfraction translations of the prostate. The aim of this investigation was to determine the magnitude of prostate rotations using 2 methods: FM coordinates and the anatomical border of the prostate and rectum. Daily computed tomography (CT) scans (n = 346) of 10 prostate cancer patients with 3 implanted FMs were acquired using the CT on rails. FM coordinates were used to determine rotation in the sagittal, transverse, and coronal planes, and CT contours of the prostate and rectum were used to determine rotation along the sagittal plane. An adaptive technique based on a subset of images (n = 6; planning and first 5 treatment CTs) to reduce systematic rotation errors in the sagittal plane was tested. The standard deviation (SD) of systematic rotation from FM coordinates was 7.6{sup o}, 7.7{sup o}, and 5.0{sup o} in the sagittal, transverse and coronal planes. The corresponding SD of random error was 10.2{sup o}, 15.8{sup o}, and 6.5{sup o}. Errors in the sagittal plane, determined from prostate and rectal contours, were 10.1{sup o} (systematic) and 7.7{sup o} (random). These results did not correlate with rotation computed from FM coordinates (r = -0.017; p = 0.753, n = 337). The systematic error could be reduced by 43% to 5.6{sup o} when the mean prostate position was estimated from 6 CT scans. Prostate rotation is a significant source of error that appears to be more accurately determined using the anatomical border of the prostate and rectum rather than FMs, thus highlighting the utility of CT image guidance.

  15. Metal Artifact Reduction and Segmentation of Dental Computerized Tomography Images Using Least Square Support Vector Machine and Mean Shift Algorithm

    PubMed Central

    Mortaheb, Parinaz; Rezaeian, Mehdi

    2016-01-01

    Segmentation and three-dimensional (3D) visualization of teeth in dental computerized tomography (CT) images are of dentists’ requirements for both abnormalities diagnosis and the treatments such as dental implant and orthodontic planning. On the other hand, dental CT image segmentation is a difficult process because of the specific characteristics of the tooth's structure. This paper presents a method for automatic segmentation of dental CT images. We present a multi-step method, which starts with a preprocessing phase to reduce the metal artifact using the least square support vector machine. Integral intensity profile is then applied to detect each tooth's region candidates. Finally, the mean shift algorithm is used to partition the region of each tooth, and all these segmented slices are then applied for 3D visualization of teeth. Examining the performance of our proposed approach, a set of reliable assessment metrics is utilized. We applied the segmentation method on 14 cone-beam CT datasets. Functionality analysis of the proposed method demonstrated precise segmentation results on different sample slices. Accuracy analysis of the proposed method indicates that we can increase the sensitivity, specificity, precision, and accuracy of the segmentation results by 83.24%, 98.35%, 72.77%, and 97.62% and decrease the error rate by 2.34%. The experimental results show that the proposed approach performs well on different types of CT images and has better performance than all existing approaches. Moreover, segmentation results can be more accurate by using the proposed algorithm of metal artifact reduction in the preprocessing phase. PMID:27014607

  16. Computerized tomography myelography with coronal and oblique coronal view for diagnosis of nerve root avulsion in brachial plexus injury

    PubMed Central

    2007-01-01

    Background The authors describe a new computerized tomography (CT) myelography technique with coronal and oblique coronal view to demonstrate the status of the cervical nerve rootlets involved in brachial plexus injury. They discuss the value of this technique for diagnosis of nerve root avulsion compared with CT myelography with axial view. Methods CT myelography was performed with penetration of the cervical subarachnoid space by the contrast medium. Then the coronal and oblique coronal reconstructions were created. The results of CT myelography were evaluated and classified with presence of pseudomeningocele, intradural ventral nerve rootlets, and intradural dorsal nerve rootlets. The diagnosis was by extraspinal surgical exploration with or without spinal evoked potential measurements and choline acetyl transferase activity measurement in 25 patients and recovery by a natural course in 3 patients. Its diagnostic accuracy was compared with that of CT myelography with axial view, correlated with surgical findings or a natural course in 57 cervical roots in 28 patients. Results Coronal and oblique coronal views were superior to axial views in visualization of the rootlets and orientation of the exact level of the root. Sensitivity and specificity for coronal and oblique coronal views of unrecognition of intradural ventral and dorsal nerve root shadow without pseudomeningocele in determining pre-ganglionic injury were 100% and 96%, respectively. There was no statistically significant difference between coronal and oblique coronal views and axial views. Conclusion The information by the coronal and oblique coronal slice CT myelography enabled the authors to assess the rootlets of the brachial plexus and provided valuable data for helping to decide whether to proceed with exploration, nerve repair, primary reconstruction. PMID:17651476

  17. Bubble propagation in a helicoidal molecular chain

    NASA Astrophysics Data System (ADS)

    Campa, Alessandro

    2001-02-01

    We study the propagation of very large amplitude localized excitations in a model of DNA that takes explicitly into account the helicoidal structure. These excitations represent the ``transcription bubble,'' where the hydrogen bonds between complementary bases are disrupted, allowing access to the genetic code. We propose these kinds of excitations in alternative to kinks and breathers. The model has been introduced by Barbi et al. [Phys. Lett. A 253, 358 (1999)], and up to now it has been used to study on the one hand low amplitude breather solutions, and on the other hand the DNA melting transition. We extend the model to include the case of heterogeneous chains, in order to get closer to a description of real DNA; in fact, the Morse potential representing the interaction between complementary bases has two possible depths, one for A-T and one for G-C base pairs. We first compute the equilibrium configurations of a chain with a degree of uncoiling, and we find that a static bubble is among them; then we show, by molecular dynamics simulations, that these bubbles, once generated, can move along the chain. We find that also in the most unfavorable case, that of a heterogeneous DNA in the presence of thermal noise, the excitation can travel for well more than 1000 base pairs.

  18. Development and evolution of the helicoidal plane of dental occlusion.

    PubMed

    Smith, B H

    1986-01-01

    The helicoidal plane of dental occlusion is a composite feature involving axial inclination of teeth and effects of dental attrition. Recent studies disagree on its distribution and significance in hominoid primates. The distribution, development, and functional basis of the helicoidal plane are investigated here, based on quantitative analysis of dental morphology and attrition in 667 human and 60 chimpanzee dentitions. Helicoidal planes are nearly universal in the human and chimpanzee dentitions studied. Increasing axial inclination of molars from M1 to M3 is primarily responsible for the helicoidal plane, although attrition acts to increase its expression. In hominoids, increased molar axial tilt appears to be associated with facial shortening and dental reduction. Population and species comparisons suggest a functional relationship with cranial structure. Progressive axial tilt of molars producing a helicoidal plane is found consistently in mammals with cheek teeth positioned partly under the cranium, as in hominids, pongids, some cebids, macropodids, ursids, and sciurids. Facial shortening is an important trend in hominid evolution and axial inclination of molars might be expected to show progressive change from Australopithecus afarensis to recent Homo sapiens. PMID:3080898

  19. Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions

    SciTech Connect

    Glick, Stephen J.; Didier, Clay

    2013-10-14

    A number of research groups have been investigating the use of dedicated breast computerized tomography (CT). Preliminary results have been encouraging, suggesting an improved visualization of masses on breast CT as compared to conventional mammography. Nonetheless, there are many challenges to overcome before breast CT can become a routine clinical reality. One potential improvement over current breast CT prototypes would be the use of photon counting detectors with cadmium zinc telluride (CZT) (or CdTe) semiconductor material. These detectors can operate at room temperature and provide high detection efficiency and the capability of multi-energy imaging; however, one factor in particular that limits image quality is the emission of characteristic x-rays. In this study, the degradative effects of characteristic x-rays are examined when using a CZT detector under breast CT operating conditions. Monte Carlo simulation software was used to evaluate the effect of characteristic x-rays and the detector element size on spatial and spectral resolution for a CZT detector used under breast CT operating conditions. In particular, lower kVp spectra and thinner CZT thicknesses were studied than that typically used with CZT based conventional CT detectors. In addition, the effect of characteristic x-rays on the accuracy of material decomposition in spectral CT imaging was explored. It was observed that when imaging with 50-60 kVp spectra, the x-ray transmission through CZT was very low for all detector thicknesses studied (0.5–3.0 mm), thus retaining dose efficiency. As expected, characteristic x-ray escape from the detector element of x-ray interaction increased with decreasing detector element size, approaching a 50% escape fraction for a 100 μm size detector element. The detector point spread function was observed to have only minor degradation with detector element size greater than 200 μm and lower kV settings. Characteristic x-rays produced increasing distortion in

  20. Quantification of Soil Physical Properties by Using X-Ray Computerized Tomography (CT) and Standard Laboratory (STD) Methods

    SciTech Connect

    Maria Ambert Sanchez

    2003-12-12

    The implementation of x-ray computerized tomography (CT) on agricultural soils has been used in this research to quantify soil physical properties to be compared with standard laboratory (STD) methods. The overall research objective was to more accurately quantify soil physical properties for long-term management systems. Two field studies were conducted at Iowa State University's Northeast Research and Demonstration Farm near Nashua, IA using two different soil management strategies. The first field study was conducted in 1999 using continuous corn crop rotation for soil under chisel plow with no-till treatments. The second study was conducted in 2001 and on soybean crop rotation for the same soil but under chisel plow and no-till practices with wheel track and no-wheel track compaction treatments induced by a tractor-manure wagon. In addition, saturated hydraulic (K{sub s}) conductivity and the convection-dispersion (CDE) model were also applied using long-term soil management systems only during 2001. The results obtained for the 1999 field study revealed no significant differences between treatments and laboratory methods, but significant differences were found at deeper depths of the soil column for tillage treatments. The results for standard laboratory procedure versus CT method showed significant differences at deeper depths for the chisel plow treatment and at the second lower depth for no-till treatment for both laboratory methods. The macroporosity distribution experiment showed significant differences at the two lower depths between tillage practices. Bulk density and percent porosity had significant differences at the two lower depths of the soil column. The results obtained for the 2001 field study showed no significant differences between tillage practices and compaction practices for both laboratory methods, but significant differences between tillage practices with wheel track and no-wheel compaction treatments were found along the soil profile for

  1. Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions

    NASA Astrophysics Data System (ADS)

    Glick, Stephen J.; Didier, Clay

    2013-10-01

    A number of research groups have been investigating the use of dedicated breast computerized tomography (CT). Preliminary results have been encouraging, suggesting an improved visualization of masses on breast CT as compared to conventional mammography. Nonetheless, there are many challenges to overcome before breast CT can become a routine clinical reality. One potential improvement over current breast CT prototypes would be the use of photon counting detectors with cadmium zinc telluride (CZT) (or CdTe) semiconductor material. These detectors can operate at room temperature and provide high detection efficiency and the capability of multi-energy imaging; however, one factor in particular that limits image quality is the emission of characteristic x-rays. In this study, the degradative effects of characteristic x-rays are examined when using a CZT detector under breast CT operating conditions. Monte Carlo simulation software was used to evaluate the effect of characteristic x-rays and the detector element size on spatial and spectral resolution for a CZT detector used under breast CT operating conditions. In particular, lower kVp spectra and thinner CZT thicknesses were studied than that typically used with CZT based conventional CT detectors. In addition, the effect of characteristic x-rays on the accuracy of material decomposition in spectral CT imaging was explored. It was observed that when imaging with 50-60 kVp spectra, the x-ray transmission through CZT was very low for all detector thicknesses studied (0.5-3.0 mm), thus retaining dose efficiency. As expected, characteristic x-ray escape from the detector element of x-ray interaction increased with decreasing detector element size, approaching a 50% escape fraction for a 100 μm size detector element. The detector point spread function was observed to have only minor degradation with detector element size greater than 200 μm and lower kV settings. Characteristic x-rays produced increasing distortion in the

  2. Dirac equation in the background of the Nutku helicoid metric

    NASA Astrophysics Data System (ADS)

    Birkandan, T.; Hortaçsu, M.

    2007-09-01

    We study the solutions of the Dirac equation in the background of the Nutku helicoid metric. This metric has curvature singularities, which necessitates imposing a boundary to exclude this point. We use the Atiyah-Patodi-Singer [Math. Proc. Cambridge Philos. Soc. 77, 43 (1975)] nonlocal spectral boundary conditions for both the four and the five dimensional manifolds.

  3. A retrospective radiographic evaluation of the anterior loop of the mental nerve: Comparison between panoramic radiography and cone beam computerized tomography

    PubMed Central

    Vujanovic-Eskenazi, Aleksandar; Valero-James, Jesus-Manuel; Sánchez-Garcés, María-Angeles

    2015-01-01

    Objectives: To compare the prevalence and the length of mental loop, measured with panoramic radiography (PR) and cone beam computerized tomography (CBCT). Material and Methods: PG and CBCT images where analyzed by a single calibrated examiner to determine the presence and the position of the mental foramen (MF), its distance to the lower mandible border, the anterior length of the mental loop (ML) and the bone quality in 82 PR and 82 CBCT. Results: ML was identified in 36.6 % of PR and 48.8 % of CBCT. PR showed a magnification of 1.87 when compared to CBCT. The mean of anterior extension of the inferior alveolar nerve and the distance to the inferior border of the mandible was higher for PR (2.8 mm, sd 0.91 mm on the PR , range 1.5 to 4.7 mm and 1.59, sd 0.9 on the CBCT ,range 0.4 to 4.0 mm) Conclusions: There is a magnification in PR images with respect to those of CBCT. The differences between CBCT and PR with regards to the identification and length of the ML are not statistically significant. Identification and accuracy measurements of ML did not depend on the bone quality. Considering that two dimensional imaging provides less accurate and reliable information regarding the anterior loop, a CBCT scan could be recommended when planning implant placement in the anterior region. Key words:Mental loop, mental nerve, mental canal, preoperative implant planning, panoramic tomography, cone beam computerized tomography. PMID:25549693

  4. Implant-guided volumetric analysis of edentulous maxillary bone with cone-beam computerized tomography scan. Maxillary sinus pneumatization classification.

    PubMed

    Tolstunov, Len; Thai, David; Arellano, Leo

    2012-08-01

    The primary goal of this anatomic study was to measure the average bone volume of the edentulous maxilla with a cone-beam computerized tomography (CBCT) scan and to determine its suitability for implant treatment without additional bone grafting. The secondary goal of the study was to estimate the degree of sinus pneumatization (SP) in reviewed CBCT scans, assess the sinus-to-maxillary bone interrelationship in edentulism, and attempt to classify maxillary sinuses based on the degree of their pneumatization. This retrospective radiographic quantitative study consisted of the analysis of CBCT scans of 30 randomly selected maxillary edentulous patients who presented in 2008-2010 to the University of the Pacific, Arthur A. Dugoni School of Dentistry, for evaluation and treatment of their edentulism. A volume of edentulous maxillary bone mesial to the maxillary sinuses (intersinal region) that can be used for a full-arch implant treatment was evaluated based on specifically selected and clinically relevant measurement criteria. There were 30 CBCT scans of maxillary edentulous patients reviewed (9 men, 21 women) with a mean age of 67.3 years (range, 41 to 92 years). The total mean maxillary bone volume (MMBV) suitable for implantation was 4 408.1 mm(3) and ranged from 1489.7 to 7263.1 mm(3). The MMBV in the study was higher than an assumed or hypothetical bone volume minimally suitable for 4-implant treatment as proposed by the authors for comparative purposes (3500 mm(3)). The degree of SP as seen on a CBCT scan (60 sinuses analyzed on panoramic images of 30 CBCT scans) had the following results in the study: SP0 (clear: not interfering with implant treatment in cases of high/small sinus), 2 sinuses or 3.3%; SP1 (mild sinus enlargement), 29 sinuses or 48.3%; SP2 (moderate SP), 16 sinuses or 26.7%; SP3 (severe SP), 9 sinuses or 15.0%; and SP4 (extreme), 4 sinuses or 6.7%. Most analyzed maxillary sinuses (47 of 60, or 78.3%) were in the clear, mild, or moderate

  5. Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions

    PubMed Central

    Glick, Stephen J.; Didier, Clay

    2013-01-01

    A number of research groups have been investigating the use of dedicated breast computerized tomography (CT). Preliminary results have been encouraging, suggesting an improved visualization of masses on breast CT as compared to conventional mammography. Nonetheless, there are many challenges to overcome before breast CT can become a routine clinical reality. One potential improvement over current breast CT prototypes would be the use of photon counting detectors with cadmium zinc telluride (CZT) (or CdTe) semiconductor material. These detectors can operate at room temperature and provide high detection efficiency and the capability of multi-energy imaging; however, one factor in particular that limits image quality is the emission of characteristic x-rays. In this study, the degradative effects of characteristic x-rays are examined when using a CZT detector under breast CT operating conditions. Monte Carlo simulation software was used to evaluate the effect of characteristic x-rays and the detector element size on spatial and spectral resolution for a CZT detector used under breast CT operating conditions. In particular, lower kVp spectra and thinner CZT thicknesses were studied than that typically used with CZT based conventional CT detectors. In addition, the effect of characteristic x-rays on the accuracy of material decomposition in spectral CT imaging was explored. It was observed that when imaging with 50-60 kVp spectra, the x-ray transmission through CZT was very low for all detector thicknesses studied (0.5–3.0 mm), thus retaining dose efficiency. As expected, characteristic x-ray escape from the detector element of x-ray interaction increased with decreasing detector element size, approaching a 50% escape fraction for a 100 μm size detector element. The detector point spread function was observed to have only minor degradation with detector element size greater than 200 μm and lower kV settings. Characteristic x-rays produced increasing

  6. X-ray computerized tomography analysis and density estimation using a sediment core from the Challenger Mound area in the Porcupine Seabight, off Western Ireland

    NASA Astrophysics Data System (ADS)

    Tanaka, Akiko; Nakano, Tsukasa; Ikehara, Ken

    2011-02-01

    X-ray computerized tomography (CT) analysis was used to image a half-round core sample of 50 cm long recovered from near Challenger Mound in the Porcupine Seabight, off western Ireland during the Integrated Ocean Drilling Program Expedition 307. This allowed three-dimensional examination of complex shapes of pebbles and ice-rafted debris in sedimentary sequences. X-ray CT analysis was also used for the determination of physical properties; a comparison between bulk density by the mass-volume method and estimated density based on linear attenuation coefficients of X-ray CT images provides insight into a spatially detailed and precise map of density variation in samples through the distribution of CT numbers.

  7. A bioinspired study on the interlaminar shear resistance of helicoidal fiber structures.

    PubMed

    Ribbans, Brian; Li, Yujie; Tan, Ting

    2016-03-01

    Helicoidal fibril structures are identified in many natural animals and plants. This research uses an integrated experimental and modeling approach to study the interlaminar shear resistance of bioinspired helicoidal fiber structures. First, helicoidal fiber-reinforced polymeric composites were created using 3D printed fiber cores and polymeric matrices, including plain, ring and helix reinforced helicoidal specimens. Then, monotonic torsional tests were performed to characterize the composite failure under interlaminar shear stresses, and fractographic characterization was conducted to elucidate corresponding fracture mechanisms in each specimen type. Finally, finite element modeling was performed to explore the critical factors on the interlaminar shear resistance of helicoidal fiber structures. The results showed that fiber-matrix modulus ratios and pitch angles of helix reinforcements played important roles on the interlaminar shear resistance of helicoidal fiber structures. PMID:26655461

  8. Vibration of skewed cantilever plates and helicoidal shells

    NASA Technical Reports Server (NTRS)

    Beres, D. P.; Bailey, C. D.

    1975-01-01

    Theoretical vibration frequencies and mode shapes are obtained for skewed plates and helicoidal shells with a cantilever boundary. Using Hamilton's law of varying action, a power series solution is developed to obtain converged numerical results for the five lowest frequencies. Effects of geometrical variables such as aspect ratio, sweep angle and shell radius to thickness ratio are investigated. Accuracy of the solution method is substantiated by comparison with existing skewed plate spherical cap, and conical shell results.

  9. Diagnosis of Vertical Root Fracture with Cone-Beam Computerized Tomography in Endodontically Treated Teeth: Three Case Reports

    PubMed Central

    Miyagaki, Daniela Cristina; Marion, Jefferson; Randi Ferraz, Caio Cézar

    2013-01-01

    A definitive diagnosis of vertical root fracture (VRF) is often a challenging task for clinicians. This is because two dimensional periapical radiographs are usually unable to detect the fracture line due to the direction of the X-ray beam. This report presents a set of 3 cases of endodontically treated teeth that were diagnosed with VRFs based on findings from clinical, radiographic, and cone-beam computerized tomographic (CBCT) examinations. After extraction, VRFs were confirmed in all cases. The presence of periodontal pockets or other signs which would compromise the correct diagnosis could not be detected in all three cases. Fracture lines were only visible with the aid of CBCT which provided useful information for the diagnosis and management of VRF. However, the clinical and radiographic data should not be discarded, but used in conjunction with CBCT. PMID:23717335

  10. Diagnosis of vertical root fracture with cone-beam computerized tomography in endodontically treated teeth: three case reports.

    PubMed

    Miyagaki, Daniela Cristina; Marion, Jefferson; Randi Ferraz, Caio Cézar

    2013-01-01

    A definitive diagnosis of vertical root fracture (VRF) is often a challenging task for clinicians. This is because two dimensional periapical radiographs are usually unable to detect the fracture line due to the direction of the X-ray beam. This report presents a set of 3 cases of endodontically treated teeth that were diagnosed with VRFs based on findings from clinical, radiographic, and cone-beam computerized tomographic (CBCT) examinations. After extraction, VRFs were confirmed in all cases. The presence of periodontal pockets or other signs which would compromise the correct diagnosis could not be detected in all three cases. Fracture lines were only visible with the aid of CBCT which provided useful information for the diagnosis and management of VRF. However, the clinical and radiographic data should not be discarded, but used in conjunction with CBCT. PMID:23717335

  11. Low dose four-dimensional computerized tomography with volume rendering reconstruction for primary hyperparathyroidism: How I do it?

    PubMed

    Platz, Timothy A; Kukar, Moshim; Elmarzouky, Rania; Cance, William; Abdelhalim, Ahmed

    2014-09-28

    Modification of 4-dimensional computed tomography (4D-CT) technique with volume rendering reconstructions and significant dose reduction is a safe and accurate method of pre-operative localization for primary hyperparathyroidism. Modified low dose 4D-CT with volume rendering reconstructions provides precise preoperative localization and is associated with a significant reduction in radiation exposure compared to classic preoperative localizing techniques. It should be considered the preoperative localization study of choice for primary hyperparathyroidism. PMID:25276315

  12. Structure and propagation of supersonic singularities from helicoidal sources

    NASA Technical Reports Server (NTRS)

    Myers, M. K.; Farassat, F.

    1987-01-01

    An asymptotic analysis of the acoustic field radiated by a supersonic helicoidal line source distribution is given. The asymptotic results are valid in the vicinity of the Mach surfaces associated with the moving sources. Particular attention is paid to the singular nature of the field on the Mach surfaces, which the analysis describes exactly. In addition, it is found that the asymptotic approximation predicts numerical values of the pressure with considerable accuracy. Some details on the field of a single source are derived as a special case.

  13. Regional cerebral blood flow during rest and skilled hand movements by xenon-133 inhalation and emission computerized tomography

    SciTech Connect

    Lauritzen, M.; Henriksen, L.; Lassen, N.A.

    1981-01-01

    Regional cerebral blood flow (CBF) was studied in 16 normal adult volunteers during rest and in 10 the study was repeated during skilled hand movements. A fast-rotating (''dynamic''), single-photon emission computerized tomograph (ECT) with four detector heads was used. Xenon-133 was inhaled over a 1-min period at a concentration of 10 mCi/L. The arrival and washout of the radioisotope was recorded during four 1-min periods. Two slices, 2 cm thick, 7 and 12 cm above the orbitomeatal line were obtained in every study. CBF averaged 60 ml/100 g/min (SD +/- 11) in the lower slice and 51 ml/100 g/min (SD +/- 13) in the upper slice. A symmetric pattern comparing right to left sides was found in both slices. Finger tapping and writing with the right hand increased CBF in specific areas of the upper slice: in the contralateral hand area by 35 +/- 15% (p less than 0.025), and in the supplementary motor area on both sides by 34 +/- 15% (p less than 0.025).

  14. Improved algorithm for computerized detection and quantification of pulmonary emphysema at high-resolution computed tomography (HRCT)

    NASA Astrophysics Data System (ADS)

    Tylen, Ulf; Friman, Ola; Borga, Magnus; Angelhed, Jan-Erik

    2001-05-01

    Emphysema is characterized by destruction of lung tissue with development of small or large holes within the lung. These areas will have Hounsfield values (HU) approaching -1000. It is possible to detect and quantificate such areas using simple density mask technique. The edge enhancement reconstruction algorithm, gravity and motion of the heart and vessels during scanning causes artefacts, however. The purpose of our work was to construct an algorithm that detects such image artefacts and corrects them. The first step is to apply inverse filtering to the image removing much of the effect of the edge enhancement reconstruction algorithm. The next step implies computation of the antero-posterior density gradient caused by gravity and correction for that. Motion artefacts are in a third step corrected for by use of normalized averaging, thresholding and region growing. Twenty healthy volunteers were investigated, 10 with slight emphysema and 10 without. Using simple density mask technique it was not possible to separate persons with disease from those without. Our algorithm improved separation of the two groups considerably. Our algorithm needs further refinement, but may form a basis for further development of methods for computerized diagnosis and quantification of emphysema by HRCT.

  15. Increased perfusion in motor areas after constraint-induced movement therapy in chronic stroke: a single-photon emission computerized tomography study.

    PubMed

    Könönen, Mervi; Kuikka, Jyrki T; Husso-Saastamoinen, Minna; Vanninen, Esko; Vanninen, Ritva; Soimakallio, Seppo; Mervaala, Esa; Sivenius, Juhani; Pitkänen, Kauko; Tarkka, Ina M

    2005-12-01

    Hemiparesis is the most common deficit after cerebral stroke. Constraint-induced movement therapy (CIMT) is a new neurorehabilitation method that emphasizes task-relevant repetitive training for the stroke hand. Twelve chronic stroke patients were studied with single-photon emission computerized tomography at rest before and after the two-week CIMT period. Increased perfusion was found in motor control related areas. The specific areas with an increase in perfusion in the affected hemisphere were in the precentral gyrus, premotor cortex (Brodmann's area 6 (BA6)), frontal cortex, and superior frontal gyrus (BA10). In the nonaffected hemisphere, perfusion was increased in the superior frontal gyrus (BA6) and cingulate gyrus (BA31). In the cerebellum increased perfusion was seen bilaterally. The brain areas with increased perfusion receive and integrate the information from different sensory systems and plan the movement execution. Regional cerebral perfusion decreased in the lingual gyrus (BA18) in the affected hemisphere. In the nonaffected frontal cortex, two areas with decreased perfusion were found in the middle frontal gyrus (BA8/10). Also, the fusiform gyrus (BA20) and inferior temporal gyrus (BA37) in the nonaffected hemisphere showed decreased perfusion. Intensive movement therapy appears to change local cerebral perfusion in areas known to participate in movement planning and execution. These changes might be a sign of active reorganization processes after CIMT in the chronic state of stroke. PMID:15931162

  16. Horizontal Bone Augmentation Using Autogenous Block Grafts and Particulate Xenograft in the Severe Atrophic Maxillary Anterior Ridges: A Cone-Beam Computerized Tomography Case Series.

    PubMed

    Monje, Alberto; Monje, Florencio; Hernández-Alfaro, Federico; Gonzalez-García, Raúl; Suárez-López del Amo, Fernando; Galindo-Moreno, Pablo; Montanero-Fernández, Jesús; Wang, Hom-Lay

    2015-07-01

    The aim of the present study was to use cone-beam computerized tomography (CBCT) to assess horizontal bone augmentation using block grafts, harvested from either the iliac crest (IC) or mandibular ramus (MR) combined with particulate xenograft and a collagen membrane for in the severe maxillary anterior ridge defects (cases Class III-IV according to Cadwood and Howell's classification). Fourteen healthy partially edentulous patients requiring extensive horizontal bone reconstruction in the anterior maxilla were selected for the study. Nineteen onlay block grafts (from IC or MR) were placed. The amount of horizontal bone gain was recorded by CBCT at 3 levels (5, 7, and 11 mm from the residual ridge) and at the time of bone grafting as well as the time of implant placement (≈5 months). Both block donor sites provided enough ridge width for proper implant placement. Nonetheless, IC had significantly greater ridge width gain than MR (Student t test) (4.93 mm vs 3.23 mm). This was further confirmed by nonparametric Mann-Whitney test (P = .007). Moreover, mean pristine ridge and grafted ridge values showed a direct association (Spearman coefficient of correlation = .336). A combination of block graft, obtained from the IC or MR, combined with particulate xenograft then covered with an absorbable collagen membrane is a predictable technique for augmenting anterior maxillary horizontal ridge deficiency. PMID:24702157

  17. Strong correlation between lung ultrasound and chest computerized tomography imaging for the detection of acute lung injury/acute respiratory distress syndrome in rats

    PubMed Central

    Ma, Huan; Huang, Daozheng; Guo, Liheng; Chen, Quanfu; Zhong, Wenzhao

    2016-01-01

    Background Lung ultrasound (LUS) is a clinical imaging technique for diagnosing acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In humans and several large animals, LUS demonstrates similar specificity and sensitivity to computerized tomography (CT) scanning. Current study evaluated the degree of agreement between LUS and CT imaging in characterizing ALI/ARDS in rats. Methods Thirty male Sprague-Dawley rats were imaged by LUS before randomization into three groups to receive intratracheal saline, 3 or 6 mg/kg LPS respectively (n=10). LUS and CT imaging was conducted 2 hours after instillation. Cross table analyses and kappa statistics were used to determine agreement levels between LUS and CT assessments of lung condition. Results Before instillation, rats presented with a largely A-pattern in LUS images, however, a significantly increase B-lines were observed in all groups after instillation and showed dose response to LPS or to saline. One rat treated with 6 mg/kg lipopolysaccharide (LPS) presented with lung consolidation. The agreement between the LUS and the CT in detecting the main characteristics of ALI/ARDS in rat was strong (r=0.758, P<0.01, k=0.737). Conclusions In conclusion, LUS detects ALI/ARDS with high agreement with micro PET/CT scanning in a rat model, suggesting that LUS represents a positive refinement in rat ALI/ARDS disease models. PMID:27499930

  18. Computerized Automated Quantification of Subcutaneous and Visceral Adipose Tissue From Computed Tomography Scans: Development and Validation Study

    PubMed Central

    Kim, Young Jae; Park, Ji Won; Kim, Jong Wan; Park, Chan-Soo; Gonzalez, John Paul S; Lee, Seung Hyun

    2016-01-01

    Background Computed tomography (CT) is often viewed as one of the most accurate methods for measuring visceral adipose tissue (VAT). However, measuring VAT and subcutaneous adipose tissue (SAT) from CT is a time-consuming and tedious process. Thus, evaluating patients’ obesity levels during clinical trials using CT scans is both cumbersome and limiting. Objective To describe an image-processing-based and automated method for measuring adipose tissue in the entire abdominal region. Methods The method detects SAT and VAT levels using a separation mask based on muscles of the human body. The separation mask is the region that minimizes the unnecessary space between a closed path and muscle area. In addition, a correction mask, based on bones, corrects the error in VAT. Results To validate the method, the volume of total adipose tissue (TAT), SAT, and VAT were measured for a total of 100 CTs using the automated method, and the results compared with those from manual measurements obtained by 2 experts. Dice’s similarity coefficients (DSCs) between the first manual measurement and the automated result for TAT, SAT, and VAT are 0.99, 0.98, and 0.97, respectively. The DSCs between the second manual measurement and the automated result for TAT, SAT, and VAT are 0.98, 0.98, and 0.97, respectively. Moreover, intraclass correlation coefficients (ICCs) between the automated method and the results of the manual measurements indicate high reliability as the ICCs for the items are all .99 (P<.001). Conclusions The results described in this paper confirm the accuracy and reliability of the proposed method. The method is expected to be both convenient and useful in the clinical evaluation and study of obesity in patients who require SAT and VAT measurements. PMID:26846251

  19. A Comparison of In-Room Computerized Tomography Options for Detection of Fiducial Markers in Prostate Cancer Radiotherapy

    SciTech Connect

    Owen, Rebecca; Foroudi, Farshad; Kron, Tomas; Milner, Alvin; Cox, Jennifer; Cramb, Jim; Zhu Li; Duchesne, Gillian

    2010-07-15

    Purpose: To compare volumetric in-room computed tomography (CT) and kilovoltage (kV) cone-beam CT (CBCT) to planar imaging with respect to their ability to localize fiducial markers (FMs) for radiotherapy of prostate cancer. Methods and Materials: Image guidance options from two linear accelerators were compared in terms of identifying the center of gravity (COG) of FMs from the isocenter: a Siemens Primatom, where the couch is rotated 180 degrees from the treatment isocenter to the in-room CT vs. electronic portal imaging (EPI); and a Varian OBI system, where kV CBCT, EPI, and planar kV radiographs were compared. In all, 387 image pairs (CBCT = 133; CT = 254) from 18 patients were analyzed. A clinical tolerance of 3 mm was predefined as the acceptable threshold for agreement. Results: COG location on in-room CT and EPI was in agreement 96.9%, 85.8%, and 89.0% of the time in the left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions, respectively, vs. 99.2%, 91.7%, and 93.2% for the CBCT and EPI analysis. The CBCT vs. kV radiographs were in agreement 100% (LR), 85.4% (SI), and 88.5% (AP), and EPI vs. kV radiographs were in agreement 100% (LR), 94.6% (SI), and 91.5% (AP) of the time. Conclusion: Identification of FMs on volumetric or planar images was found to be not equivalent ({+-}3 mm) using either linear accelerator. Intrafraction prostate motion, interpretation of FM location, and spatial properties of images are contributing factors. Although in-room CT has superior image quality, the process of realigning the treatment couch to acquire a CT introduces an error, highlighting the benefits of a single isocentric system.

  20. Computerized tomography based “patient specific blocks” improve postoperative mechanical alignment in primary total knee arthroplasty

    PubMed Central

    Vaishya, Raju; Vijay, Vipul; Birla, Vikas P; Agarwal, Amit K

    2016-01-01

    AIM: To compare the postoperative mechanical alignment achieved after total knee arthroplasty (TKA) using computer tomography (CT) based patient specific blocks (PSB) to conventional instruments (CI). METHODS: Total 80 knees were included in the study, with 40 knees in both the groups operated using PSB and CI. All the knees were performed by a single surgeon using the same cruciate sacrificing implants. In our study we used CT based PSB to compare with CI. Postoperative mechanical femoro-tibial angle (MFT angle) was measured on long leg x-rays using picture archiving and communication system (PACS). We compared mechanical alignment achieved using PSB and CI in TKA using statistical analysis. RESULTS: The PSB group (group 1) included 17 females and seven males while in CI group (group 2) there were 15 females and eight males. The mean age of patients in group 1 was 60.5 years and in group 2 it was 60.2 years. The mean postoperative MFT angle measured on long-leg radiographs in group 1 was 178.23° (SD = 2.67°, range: 171.9° to 182.5°) while in group 2, the mean MFT angle was 175.73° (SD = 3.62°, range: 166.0° to 179.8°). There was significant improvement in postoperative mechanical alignment (P value = 0.001), in PSB group compared to CI. Number of outliers were also found to be less in group operated with PSB (7 Knee) compared to those operated with CI (17 Knee). CONCLUSION: PSB improve mechanical alignment after total knee arthroplasty, compared to CI. This may lead to lower rates of revision in the PSB based TKA as compared to the conventional instrumentation. PMID:27458553

  1. Therapeutic monitoring of experimental invasive pulmonary aspergillosis by ultrafast computerized tomography, a novel, noninvasive method for measuring responses to antifungal therapy.

    PubMed Central

    Walsh, T J; Garrett, K; Feurerstein, E; Girton, M; Allende, M; Bacher, J; Francesconi, A; Schaufele, R; Pizzo, P A

    1995-01-01

    Pulmonary infiltrates in neutropenic hosts with invasive aspergillosis are due to vascular invasion and hemorrhagic infarction. In order to measure the effect of antifungal compounds on this organism-mediated tissue injury, we monitored the course of pulmonary infiltrates by serial ultrafast computerized tomography (UFCT) in persistently granulocytopenic rabbits with experimental invasive pulmonary aspergillosis. The course of pulmonary lesions measured by serial UFCT scans was compared with those measured by conventional chest radiography, histopathological resolution of lesions, and microbiological clearance of Aspergillus fumigatus. Treatment groups included either amphotericin B colloidal dispersion in dosages of 1, 5, and 10 mg/kg of body weight per day intravenously or conventional desoxycholate amphotericin B at 1 mg/kg/day intravenously. Therapeutic monitoring of pulmonary lesions by UFCT demonstrated a significant dose-response relationship. Lesions continued to progress in untreated controls, whereas lesions in treated rabbits initially increased and then decreased in response to antifungal therapy in a dosage-dependent manner (P < or = 0.05 to P < or = 0.005, depending upon the groups compared). This same trend of resolution of lesions in response to antifungal therapy was also demonstrated by postmortem examination and by microbiological clearance of the organism. These data indicated that amphotericin B colloidal dispersion at 5 and 10 mg/kg/day exerted a more rapid rate of clearance of lesions than conventional amphotericin B. UFCT was more sensitive than conventional chest radiography in detecting lesions due to invasive pulmonary aspergillosis (P < 0.05 to P < 0.005, depending upon the groups compared). These findings establish a correlation among UFCT-defined lesions, microbiological response, and resolution of pathologically defined lesions in experimental invasive pulmonary aspergillosis. Serial monitoring of UFCT-defined lesions of aspergillosis

  2. Pedicle Screw Placement in the Thoracolumbar Spine Using a Novel, Simple, Safe, and Effective Guide-Pin : A Computerized Tomography Analysis

    PubMed Central

    Hyun, Seung-Jae; Kim, Yongjung J.; Cheh, Gene; Cho, Samuel K.

    2015-01-01

    Objective To improve pedicle screw placement accuracy with minimal radiation and low cost, we developed specially designed K-wire with a marker. To evaluate the accuracy of thoracolumbar pedicle screws placed using the novel guide-pin and portable X-rays. Methods Observational cohort study with computerized tomography (CT) analysis of in vivo and in vitro pedicle screw placement. Postoperative CT scans of 183 titanium pedicle screws (85 lumbar and 98 thoracic from T1 to L5) placed into 2 cadavers and 18 patients were assessed. A specially designed guide-pin with a marker was inserted into the pedicle to identify the correct starting point (2 mm lateral to the center of the pedicle) and aiming point (center of the pedicle isthmus) in posteroanterior and lateral X-rays. After radiographically confirming the exact starting and aiming points desired, a gearshift was inserted into the pedicle from the starting point into the vertebral body through the center of pedicle isthmus. Results Ninety-nine percent (181/183) of screws were contained within the pedicle (total 183 pedicle screws : 98 thoracic pedicle screws and 85 lumbar screws). Only two of 183 (1.0%) thoracic pedicle screws demonstrated breach (1 lateral in a patient and 1 medial in a cadaver specimen). None of the pedicle breaches were associated with neurologic or other clinical sequelae. Conclusion A simple, specially designed guide-pin with portable X-rays can provide correct starting and aiming points and allows for accurate pedicle screw placement without preoperative CT scan and intraoperative fluoroscopic assistance. PMID:26279807

  3. The Detectability and Localization Accuracy of Implanted Fiducial Markers Determined on In-Room Computerized Tomography (CT) and Electronic Portal Images (EPI)

    SciTech Connect

    Owen, Rebecca Kron, Tomas; Foroudi, Farshad; Cox, Jennifer; Zhu Li; Cramb, Jim; Sparks, Laura; Duchesne, Gillian

    2008-10-01

    Many different methods of image guidance are available for radiotherapy treatment (IGRT). The aims of the study were (1) to determine the optimal diameter of gold markers for IGRT to the prostate; (2) to compare, using the Siemens Primatom, the relative merits of in-room computerized tomography (CT) and electronic portal image (EPI) for locating the marker seeds. Gold markers of differing widths were embedded in 2 phantoms (perspex slabs and anthropomorphic). Images were acquired with an amorphous silicon flat panel detector (Siemens Optivue 500) and with the in-room CT scanner (Siemens Somatom Balance). The EPIs were reviewed independently by 6 operators to determine which diameter marker could be best visualized. The optimal marker technique was determined by comparing the investigators' observed marker co-ordinates with the known locations within the phantom. The visibility of all markers on anterior-posterior EPIs was 100%. On the lateral EPI, of a possible 180 visualizations of 1.2-, 1.0-, and 0.8-mm diameter markers, 176 (97.8%), 151 (83.9%), and 132 (73.3%), respectively, were successful. On EPI, the average deviation of fiducial markers from the known position was less than 0.5 mm in any direction. On CT, the largest deviation (2.17 mm) of markers from the known coordinate position was in the superior-inferior direction, reflecting the 3.0-mm slice thickness used. EPI accurately located internal markers in all dimensions. The availability of 'gold standard' CT imagery at the treatment unit does not improve how accurately the position of markers in a phantom can be defined compared with EPI. However, CT imagery does provide important soft tissue information, the benefits of which are being investigated further.

  4. The minimum residual root thickness after using ProTaper, RaCe and Gates-Glidden drills: A cone beam computerized tomography study

    PubMed Central

    Akhlaghi, Nahid Mohammadzadeh; Bajgiran, Laleh Mohammadian; Naghdi, Amirali; Behrooz, Elaheh; Khalilak, Zohreh

    2015-01-01

    Objective: The aim of this study was to evaluate the minimum residual root thickness (MRRT) of the danger zone after preflaring of the mesio-buccal (MB) canal of mandibular first molars using ProTaper, RaCe and Gates-Glidden (GG) drills as coronal shapers by cone beam computerized tomography (CBCT). Materials and Methods: In this experimental study, the initial CBCT scans of 75 MB canals of mandibular first molars were provided within 1, 2, 3 and 4 mm of the furcation level. The samples were divided into three groups. The samples of ProTaper and RaCe groups were prepared up to F2 and #25.04 as the master apical file (MAF), respectively. The coronal preparation of the samples in the GG group was done using GG drills #2, #3 and #4 and canals were prepared till MAF # 25. After obtaining the postinstrumentation images, the MRRT and the amount of removed dentin were analyzed by t-test and ANOVA statistical analyses. Results: The GG drills removed significantly more dentin than RaCe at all the sections (P < 0.05) and more than ProTaper at 3 mm from the furcation. Statistically there was no significant difference between ProTaper and RaCe groups (P > 0.05). There was no significant difference in MRRT between the groups (P > 0.05). The mean MRRT was not < 0.75 mm at all sections. Conclusion: Based on the results of this study, when an appropriate root thickness is initially present, all of the instruments that were investigated may safely be used as coronal shapers in MB canals of mandibular first molars. PMID:26038655

  5. Electronic structure of helicoidal graphene: Massless Dirac particles on a curved surface with a screw symmetry

    NASA Astrophysics Data System (ADS)

    Watanabe, Masataka; Komatsu, Hisato; Tsuji, Naoto; Aoki, Hideo

    2015-11-01

    Massless Dirac particles on the helicoid are theoretically investigated. With its possible application being helical graphene, we explore how the peculiarities of Dirac particles appear on the curved, screw-symmetric surface. Zweibein is used to derive the massless Dirac equation on the helicoid and on general curved surfaces. We show that bound states of massless Dirac electrons on the helicoid are absent, and thus the system is fully characterized by the scattering probabilities and the phase shifts. We obtain these quantities from numerically calculated wave functions. We find the local density of states and the phase shifts behave characteristically around the axis of the helicoid. Bound states of massive Dirac electrons on the surface are also shown to be absent as an extension of the above result on massless Dirac electrons. A comparison with the nonrelativistic case is also made.

  6. Helical computerized tomography and NT-proBNP for screening of right ventricular overload on admission and at long term follow-up of acute pulmonary embolism

    PubMed Central

    2012-01-01

    Background Right ventricular dysfunction (RVD) in acute pulmonary embolism (APE) can be assessed with helical computerized tomography (CT) and transthoracic echocardiography (TTE). Signs of RVD and elevated natriuretic peptides like NT-proBNP and cardiac troponin (TnT) are associated with increased risk of mortality. However, the prognostic role of both initial diagnostic strategy and the use of NT-proBNP and TnT for screening for long-term probability of RVD remains unknown. The aim of the study was to determine the role of helical CT and NT-proBNP in detection of RVD in the acute phase. In addition, the value of NT-proBNP for ruling out RVD at long-term follow-up was assessed. Methods Sixty-three non-high risk APE patients were studied. RVD was assessed at admission in the emergency department by CT and TTE, and both NT-proBNP and TnT samples were taken. These, excepting CT, were repeated seven months later. Results At admission RVD was detected by CT in 37 (59 %) patients. RVD in CT correlated strongly with RVD in TTE (p < 0.0001). NT-proBNP was elevated (≥ 350 ng/l) in 32 (86 %) patients with RVD but in only seven (27 %) patients without RVD (p < 0.0001). All the patients survived until the 7-month follow-up. TTE showed persistent RVD in 6 of 63 (10 %) patients who all had RVD in CT at admission. All of them had elevated NT-proBNP levels in the follow-up compared with 5 (9 %) of patients without RVD (p < 0.0001). Conclusions TTE does not confer further benefit when helical CT is used for screening for RVD in non-high risk APE. All the patients who were found to have RVD in TTE at seven months follow-up had had RVD in the acute phase CT as well. Thus, patients without RVD in diagnostic CT do not seem to require further routine follow-up to screen for RVD later. On the other hand, persistent RVD and thus need for TTE control can be ruled out by assessment of NT-proBNP at follow-up. A follow-up protocol based on these findings is suggested. PMID:22559861

  7. NOTE: Cone beam computerized tomography: the effect of calibration of the Hounsfield unit number to electron density on dose calculation accuracy for adaptive radiation therapy

    NASA Astrophysics Data System (ADS)

    Hatton, Joan; McCurdy, Boyd; Greer, Peter B.

    2009-08-01

    The availability of cone beam computerized tomography (CBCT) images at the time of treatment has opened possibilities for dose calculations representing the delivered dose for adaptive radiation therapy. A significant component in the accuracy of dose calculation is the calibration of the Hounsfield unit (HU) number to electron density (ED). The aim of this work is to assess the impact of HU to ED calibration phantom insert composition and phantom volume on dose calculation accuracy for CBCT. CBCT HU to ED calibration curves for different commercial phantoms were measured and compared. The effect of the scattering volume of the phantom on the HU to ED calibration was examined as a function of phantom length and radial diameter. The resulting calibration curves were used at the treatment planning system to calculate doses for geometrically simple phantoms and a pelvic anatomical phantom to compare against measured doses. Three-dimensional dose distributions for the pelvis phantom were calculated using the HU to ED curves and compared using Chi comparisons. The HU to ED calibration curves for the commercial phantoms diverge at densities greater than that of water, depending on the elemental composition of the phantom insert. The effect of adding scatter material longitudinally, increasing the phantom length from 5 cm to 26 cm, was found to be up to 260 HU numbers for the high-density insert. The change in the HU value, by increasing the diameter of the phantom from 18 to 40 cm, was found to be up to 1200 HU for the high-density insert. The effect of phantom diameter on the HU to ED curve can lead to dose differences for 6 MV and 18 MV x-rays under bone inhomogeneities of up to 20% in extreme cases. These results show significant dosimetric differences when using a calibration phantom with materials which are not tissue equivalent. More importantly, the amount of scattering material used with the HU to ED calibration phantom has a significant effect on the dosimetric

  8. The natural history of the helicoidal occlusal plane and its evolution in early Homo.

    PubMed

    Tobias, P V

    1980-08-01

    In modern man the pitch of the occlusal plane may vary along the tooth-row. When anterior cheek-teeth show a plane sloping upward palatally, whilst that on posterior cheek-teeth slopes upward buccally, there results a twisted or helicoidal occlusal plane (Ackermann). Several hypotheses have been proposed for the structural basis of the helicoidal occlusal plane. Campbell's proposal ('25) has gained widest acceptance, namely that the helicoid results from anteroposterior differences in upper and lower alveolar arch width. In the early 1960s, while studying the Olduvai hominids assigned to Homo habilis, the author noted changing occlusal slopes along the tooth-row and a slight helicoid, although these featues had not been noted in other early hominids. Subsequently, Wallace showed a total absence of the helicoid from South African australopithecines, and its presence in Swartkrans Homo, SK 45 and SK 80. Recent studies confirm the presence of the helicoid in all available specimens of H. habilis, including Stw 53 found at Sterkfontein in 1976. Hence, this trait may distinguish between Australopithecus and early Homo. Measurements of the maxillary arch widths have shown that, whereas in Australopithecus arch widths increase to a maximum at M3, in early Homo maxillary arch widths are greatest at M2. The decline in posterior maxillary arch width is part of a general reduction of that region. Thus despite striking elongation of premolars and M1 in early Homo, M2 and M3 are mesiodistally abbreviated. It is hypothesized that the onset of posterior arch reduction, with the appearance of a helicoid, was a structural and functional concomitant of the transition from the presumed australopithecine ancestor to H. habilis. PMID:6774617

  9. High-resolution nuclear magnetic resonance imaging and single photon emission computerized tomography--cerebral blood flow in a case of pure sensory stroke and mild dementia owing to subcortical arteriosclerotic encephalopathy (Binswanger's disease)

    SciTech Connect

    De Chiara, S.; Lassen, N.A.; Andersen, A.R.; Gade, A.; Lester, J.; Thomsen, C.; Henriksen, O.

    1987-01-01

    Pure sensory stroke (PSS) is typically caused by a lacunar infarct located in the ventral-posterior (VP) thalamic nucleus contralateral to the paresthetic symptoms. The lesion is usually so small that it cannot be seen on computerized tomography (CT), as illustrated by our case. In our moderately hypertensive, 72-year-old patient with PSS, CT scanning and conventional nuclear magnetic resonance imaging (NMRI) scanning using a 7-mm-thick slice on a 1.5 Tesla instrument all failed to visualize the thalamic infarct. Using the high-resolution mode with 2-mm slice thickness it was, however, clearly seen. In addition, NMRI unexpectedly showed diffuse periventricular demyelinization as well as three other lacunar infarcts, i.e., findings characteristic of subcortical arteriosclerotic encephalopathy (SAE). This prompted psychometric testing, which revealed signs of mild (subclinical) dementia, in particular involving visiospatial apraxia; this pointed to decreased function of the right parietal cortex, which was structurally intact on CT and NMRI. Single photon emission computerized tomography by Xenon-133 injection and by hexamethyl-propyleneamine-oxim labeled with Technetium-99m showed asymmetric distribution of cerebral blood flow (CBF), with an 18% lower value in the right parietal cortex compared to the left side; this indicated asymmetric disconnection of the cortex by the SAE. Thus, the tomograms of the functional parameter, CBF, correlated better with the deficits revealed by neuropsychological testing than by CT or NMRI.

  10. Wave transmission in time- and space-variant helicoidal phononic crystals

    NASA Astrophysics Data System (ADS)

    Li, F.; Chong, C.; Yang, J.; Kevrekidis, P. G.; Daraio, C.

    2014-11-01

    We present a dynamically tunable mechanism of wave transmission in one-dimensional helicoidal phononic crystals in a shape similar to DNA structures. These helicoidal architectures allow slanted nonlinear contact among cylindrical constituents, and the relative torsional movements can dynamically tune the contact stiffness between neighboring cylinders. This results in cross-talking between in-plane torsional and out-of-plane longitudinal waves. We numerically demonstrate their versatile wave mixing and controllable dispersion behavior in both wavenumber and frequency domains. Based on this principle, a suggestion toward an acoustic configuration bearing parallels to a transistor is further proposed, in which longitudinal waves can be switched on and off through torsional waves.

  11. Emission tomography of the kidney

    SciTech Connect

    Teates, C.D.; Croft, B.Y.; Brenbridge, N.A.; Bray, S.T.; Williamson, B.R.

    1983-12-01

    Single photon emission computerized tomography (SPECT) was done on two patients with suspected renal masses. Nuclear scintigraphy was equivocal on two tumors readily identified by SPECT. Single photon tomography is cost effective and increases the reliability of nuclear scintigraphy.

  12. Pleural-based changes on chest x-ray after irradiation for primary breast cancer: correlation with findings on computerized tomography

    SciTech Connect

    Srinivasan, G.; Kurtz, D.W.; Lichter, A.S.

    1983-10-01

    In treating breast cancer with excisional biopsy and irradiation, a volume of lung underlying the breast and chest wall receives significant doses of irradiation. This irradiation can produce pleural and pulmonary changes that can be seen on routine chest radiographs. In five such cases, we have examined pre and post-treatment computerized tomograms of the chest and show that these radiographic changes are pleural-based and lie within the high dose radiation volume. Failure to correct radiation treatment plans for the influence of lung density results in an increased dose to lung and pleura that could, in theory, exacerbate pulmonary and pleural radiation effects.

  13. Computerized tomographic evaluation of aortic prosthetic graft complications

    SciTech Connect

    Kay, D.; Kalmar, J.A.

    1985-03-01

    Computerized tomography has been found to be an accurate and sensitive method of diagnosing complications of synthetic aortic grafts. Complications in this series of four cases included aortoesophageal fistula, aortoduodenal fistula, pseudoaneurysm, and retroperitoneal hematoma. 6 references, 5 figures.

  14. The ability of cone-beam computerized tomography to detect vertical root fractures in endodontically treated and nonendodontically treated teeth: a report of 3 cases.

    PubMed

    Zou, Xiaoying; Liu, Denggao; Yue, Lin; Wu, Minkai

    2011-06-01

    A definitive diagnosis of vertical root fracture (VRFs) is often a challenging task for clinicians. Two-dimensional periapical radiographs (PRs) may be not helpful in such a diagnosis when the x-ray beam is not parallel to the plane of the fracture line. This report presents a set of 3 cases in which 1 endodontically treated and 2 nonendodontically treated mandibular molars were diagnosed with VRFs based on findings from clinical, radiographic, and cone-beam computerized tomographic (CBCT) examinations. After extraction, VRFs were confirmed in all of the teeth. Deep and narrow periodontal pockets were detected in 2 molars. A widening of the root canal space was observed in the PR of 1 molar only, and crown cracks were detected in none of these cases. However, in all 3 molars, fracture lines were visible on the CBCT images. Thus, CBCT provided useful information in diagnosing VRFs in both endodontically treated and nonendodontically treated teeth, especially when VRFs could not be confirmed by clinical findings and PRs. PMID:21439864

  15. Clinical evaluation of a high-resolution new peripheral quantitative computerized tomography (pQCT) scanner for the bone densitometry at the lower limbs

    NASA Astrophysics Data System (ADS)

    Braun, M. J.; Meta, M. D.; Schneider, P.; Reiners, Chr

    1998-08-01

    Precision, long-term stability, linearity and accuracy of the x-ray peripheral quantitative computerized tomographic (pQCT) bone scanner XCT 3000 (Norland-Stratec Medical Sys.) were evaluated using the European Forearm Phantom (EFP). In vivo measurements were assessed using a standardized procedure at the distal femur and the distal tibia. In the patient-scan mode, the spatial resolution of the system was lp/mm as measured at the 10% level of the modulation transfer function (MTF). The contrast-detail diagram (CDD) yielded a minimal difference in attenuation coefficient (AC) of 0.07 at an object size of 0.5 mm. The effective dose for humans was calculated to be less than 1.5 Sv per scan. Short-term precision in vivo was expressed as root mean square standard deviation of paired measurements of 20 healthy volunteers (%). At the distal femur total volumetric density (ToD) and total cross-sectional area (ToA) were found to be less sensitive to positioning errors than at the distal tibia. Structural parameters like the polar cross-sectional moment of inertia or the polar cross-sectional moment of resistance showed a good short-term precision at the distal femur ( and 1.4%). The relation between the two skeletal sites with respect to or showed a high

  16. Divergence of a helicoidal shell in a pipe with a flowing fluid

    NASA Astrophysics Data System (ADS)

    Eliseev, V. V.; Vetyukov, Yu. M.; Zinov'eva, T. V.

    2011-05-01

    This paper considers a solution of the problem of coupled hydroelasticity for a helicoidal shell in a rigid tube with a flowing ideal incompressible fluid, which is of interest for the design of heat exchange systems. The flow is considered potential, and boundary conditions are imposed on the deformed surface. The version of the classical theory of elastic shells as the Lagrangian mechanics of deformable surfaces is used. The longitudinal-torsional vibrations of a long shell and a naturally twisted rod are studied. It is established that the obtained hydrodynamic loads are conservative, so that a divergence type instability is possible. A critical combination of parameters is determined.

  17. Complex incommensurate helicoidal magnetic ordering of EuNiGe3.

    PubMed

    Ryan, D H; Cadogan, J M; Rejali, Rasa; Boyer, C D

    2016-07-01

    (151)Eu Mössbauer spectroscopy and neutron powder diffraction are combined to show that the tetragonal (I4mm #107) compound EuNiGe3 orders magnetically below [Formula: see text] K and adopts a complex incommensurate helicoidal magnetic structure at 3.6 K, with a propagation vector [Formula: see text] and a Eu moment of 7.1(2) [Formula: see text]. On warming through 6 K an incommensurate sinusoidal modulation develops and dominates the magnetic order by 12 K. PMID:27173847

  18. Complex incommensurate helicoidal magnetic ordering of EuNiGe3

    NASA Astrophysics Data System (ADS)

    Ryan, D. H.; Cadogan, J. M.; Rejali, Rasa; Boyer, C. D.

    2016-07-01

    151Eu Mössbauer spectroscopy and neutron powder diffraction are combined to show that the tetragonal (I4mm #107) compound EuNiGe3 orders magnetically below {{T}\\text{N}}∼ 14 K and adopts a complex incommensurate helicoidal magnetic structure at 3.6 K, with a propagation vector \\mathbf{k}=≤ft[0.255(1),~0.054(14),~0\\right] and a Eu moment of 7.1(2) {μ\\text{B}} . On warming through 6 K an incommensurate sinusoidal modulation develops and dominates the magnetic order by 12 K.

  19. Nontrivial Bloch oscillation and Zener tunneling frequencies in helicoidal molecules due to spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Caetano, R. A.

    2014-05-01

    Bloch oscillation and Zener tunneling are investigated in helicoidal molecules, with DNA as the representative example, in the presence of spin-orbit coupling induced by electrical charges accumulated along the structure of the molecule. We show that the presence of the spin-orbit coupling does not destroy the Bloch oscillations and, further, it induces the appearance of nontrivial Bloch oscillation frequencies associated with resonances among Wannier-Stark states. The Zener tunneling between the spin states is also studied here by looking at the time evolution of the polarization of the wave packet. The results show that the polarization also oscillates with nontrivial well-determined frequencies.

  20. Predictive value of excretory urography, ultrasonography, computerized tomography, and liver and bone scan in the staging of bilharzial bladder cancer in Saudi Arabia

    SciTech Connect

    Hanash, K.A.; Bissada, N.K.; Abla, A.; Esmail, D.; Dowling, A.

    1984-07-01

    The role of ultrasonography, computed tomography (CT), and radioisotopic scanning in the staging of bilharzial bladder cancer has not been reported previously. Forty patients with invasive bladder cancer seen at the King Faisal Specialist Hospital and Research Centre between January 1978 and June 1981 underwent complete preoperative workup for staging of their tumors prior to radical cystectomy. The preoperative radiologic investigations included excretory urography (IVP), ultrasonography (US), CT of the pelvis, and liver and bone scans. The results of these investigations were compared with the operative and pathologic staging. Ninety-three percent of the patients with bilharzial cancer had evidence of ureteric obstruction on IVP compared with 22% of the nonbilharzial cancer patients. The presence of ureteric obstruction in these patients did not correlate with the stage of the disease with 83% of the patients with superficial tumors (T1 and T2) having hydroureteronephrosis. Ultrasonography and CT had an 83% accuracy in the staging of superficial tumors. Stage T3 tumors were understaged in 14% of the cases. Ultrasonography did not differentiate Stages T3 and T4 tumors while CT scan differentiated these two stages in 57% of the cases. Bone scan failed to reveal evidence of metastatic disease in any of the bilharzial cancer patients. Liver scan was suspicious for liver metastases in two patients with bilharzial cancers in whom open liver biopsy revealed only hepatic bilharziasis. Of all the radiographic studies, US or preferably CT scan seem to be of some value in the staging of bilharzial tumors localized to the bladder. Bone and liver scans are probably of no cost effective benefit.

  1. A general framework and review of scatter correction methods in x-ray cone-beam computerized tomography. Part 1: Scatter compensation approaches

    SciTech Connect

    Ruehrnschopf, Ernst-Peter; Klingenbeck, Klaus

    2011-07-15

    Since scattered radiation in cone-beam volume CT implies severe degradation of CT images by quantification errors, artifacts, and noise increase, scatter suppression is one of the main issues related to image quality in CBCT imaging. The aim of this review is to structurize the variety of scatter suppression methods, to analyze the common structure, and to develop a general framework for scatter correction procedures. In general, scatter suppression combines hardware techniques of scatter rejection and software methods of scatter correction. The authors emphasize that scatter correction procedures consist of the main components scatter estimation (by measurement or mathematical modeling) and scatter compensation (deterministic or statistical methods). The framework comprises most scatter correction approaches and its validity also goes beyond transmission CT. Before the advent of cone-beam CT, a lot of papers on scatter correction approaches in x-ray radiography, mammography, emission tomography, and in Megavolt CT had been published. The opportunity to avail from research in those other fields of medical imaging has not yet been sufficiently exploited. Therefore additional references are included when ever it seems pertinent. Scatter estimation and scatter compensation are typically intertwined in iterative procedures. It makes sense to recognize iterative approaches in the light of the concept of self-consistency. The importance of incorporating scatter compensation approaches into a statistical framework for noise minimization has to be underscored. Signal and noise propagation analysis is presented. A main result is the preservation of differential-signal-to-noise-ratio (dSNR) in CT projection data by ideal scatter correction. The objective of scatter compensation methods is the restoration of quantitative accuracy and a balance between low-contrast restoration and noise reduction. In a synopsis section, the different deterministic and statistical methods are

  2. A new computerized ionosphere tomography model using the mapping function and an application to the study of seismic-ionosphere disturbance

    NASA Astrophysics Data System (ADS)

    Kong, Jian; Yao, Yibin; Liu, Lei; Zhai, Changzhi; Wang, Zemin

    2016-05-01

    A new algorithm for ionosphere tomography using the mapping function is proposed in this paper. First, the new solution splits the integration process into four layers along the observation ray, and then, the single-layer model (SLM) is applied to each integration part using a mapping function. Next, the model parameters are estimated layer by layer with the Kalman filtering method by introducing the scale factor (SF) γ to solve the ill-posed problem. Finally, the inversed images of different layers are combined into the final CIT image. We utilized simulated data from 23 IGS GPS stations around Europe to verify the estimation accuracy of the new algorithm; the results show that the new CIT model has better accuracy than the SLM in dense data areas and the CIT residuals are more closely grouped. The stability of the new algorithm is discussed by analyzing model accuracy under different error levels (the max errors are 5TECU, 10TECU, 15TECU, respectively). In addition, the key preset parameter, SFγ , which is given by the International Reference Ionosphere model (IRI2012). The experiment is designed to test the sensitivity of the new algorithm to SF variations. The results show that the IRI2012 is capable of providing initial SF values. Also in this paper, the seismic-ionosphere disturbance (SID) of the 2011 Japan earthquake is studied using the new CIT algorithm. Combined with the TEC time sequence of Sat.15, we find that the SID occurrence time and reaction area are highly related to the main shock time and epicenter. According to CIT images, there is a clear vertical electron density upward movement (from the 150-km layer to the 450-km layer) during this SID event; however, the peak value areas in the different layers were different, which means that the horizontal movement velocity is not consistent among the layers. The potential physical triggering mechanism is also discussed in this paper. Compared with the SLM, the RMS of the new CIT model is improved by

  3. A new computerized ionosphere tomography model using the mapping function and an application to the study of seismic-ionosphere disturbance

    NASA Astrophysics Data System (ADS)

    Kong, Jian; Yao, Yibin; Liu, Lei; Zhai, Changzhi; Wang, Zemin

    2016-08-01

    A new algorithm for ionosphere tomography using the mapping function is proposed in this paper. First, the new solution splits the integration process into four layers along the observation ray, and then, the single-layer model (SLM) is applied to each integration part using a mapping function. Next, the model parameters are estimated layer by layer with the Kalman filtering method by introducing the scale factor (SF) γ to solve the ill-posed problem. Finally, the inversed images of different layers are combined into the final CIT image. We utilized simulated data from 23 IGS GPS stations around Europe to verify the estimation accuracy of the new algorithm; the results show that the new CIT model has better accuracy than the SLM in dense data areas and the CIT residuals are more closely grouped. The stability of the new algorithm is discussed by analyzing model accuracy under different error levels (the max errors are 5TECU, 10TECU, 15TECU, respectively). In addition, the key preset parameter, SFγ , which is given by the International Reference Ionosphere model (IRI2012). The experiment is designed to test the sensitivity of the new algorithm to SF variations. The results show that the IRI2012 is capable of providing initial SF values. Also in this paper, the seismic-ionosphere disturbance (SID) of the 2011 Japan earthquake is studied using the new CIT algorithm. Combined with the TEC time sequence of Sat.15, we find that the SID occurrence time and reaction area are highly related to the main shock time and epicenter. According to CIT images, there is a clear vertical electron density upward movement (from the 150-km layer to the 450-km layer) during this SID event; however, the peak value areas in the different layers were different, which means that the horizontal movement velocity is not consistent among the layers. The potential physical triggering mechanism is also discussed in this paper. Compared with the SLM, the RMS of the new CIT model is improved by

  4. Computerized Data Management.

    ERIC Educational Resources Information Center

    Grzywinski, Carol M.

    1983-01-01

    Argues that a computerized data management system can help the developmental educator maintain professional accountability. Reports on a project conducted at the State University of New York Agricultural and Technical College at Canton during which paperwork was reduced and report writing expedited through a computerized management information…

  5. Innovations in Computerized Assessment.

    ERIC Educational Resources Information Center

    Drasgow, Fritz, Ed.; Olson-Buchanan, Julie B., Ed.

    Chapters in this book present the challenges and dilemmas faced by researchers as they created new computerized assessments, focusing on issues addressed in developing, scoring, and administering the assessments. Chapters are: (1) "Beyond Bells and Whistles; An Introduction to Computerized Assessment" (Julie B. Olson-Buchanan and Fritz Drasgow);…

  6. Computerized Fleet Maintenance.

    ERIC Educational Resources Information Center

    Cataldo, John J.

    1985-01-01

    The Computerized Fleet Maintenance (CFM) program of a New York school district has major component areas of garage operation, vehicle replacement, and fuel consumption. CFM detects high expenditures and provides the rationale for bus replacement. (MLF)

  7. Spin-Current and Spin-Splitting in Helicoidal Molecules Due to Spin-Orbit Coupling

    PubMed Central

    Caetano, R. A.

    2016-01-01

    The use of organic materials in spintronic devices has been seriously considered after recent experimental works have shown unexpected spin-dependent electrical properties. The basis for the confection of any spintronic device is ability of selecting the appropriated spin polarization. In this direction, DNA has been pointed out as a potential candidate for spin selection due to the spin-orbit coupling originating from the electric field generated by accumulated electrical charges along the helix. Here, we demonstrate that spin-orbit coupling is the minimum ingredient necessary to promote a spatial spin separation and the generation of spin-current. We show that the up and down spin components have different velocities that give rise to a spin-current. By using a simple situation where spin-orbit coupling is present, we provide qualitative justifications to our results that clearly point to helicoidal molecules as serious candidates to integrate spintronic devices. PMID:27009836

  8. Spin-Current and Spin-Splitting in Helicoidal Molecules Due to Spin-Orbit Coupling

    NASA Astrophysics Data System (ADS)

    Caetano, R. A.

    2016-03-01

    The use of organic materials in spintronic devices has been seriously considered after recent experimental works have shown unexpected spin-dependent electrical properties. The basis for the confection of any spintronic device is ability of selecting the appropriated spin polarization. In this direction, DNA has been pointed out as a potential candidate for spin selection due to the spin-orbit coupling originating from the electric field generated by accumulated electrical charges along the helix. Here, we demonstrate that spin-orbit coupling is the minimum ingredient necessary to promote a spatial spin separation and the generation of spin-current. We show that the up and down spin components have different velocities that give rise to a spin-current. By using a simple situation where spin-orbit coupling is present, we provide qualitative justifications to our results that clearly point to helicoidal molecules as serious candidates to integrate spintronic devices.

  9. Spin-Current and Spin-Splitting in Helicoidal Molecules Due to Spin-Orbit Coupling.

    PubMed

    Caetano, R A

    2016-01-01

    The use of organic materials in spintronic devices has been seriously considered after recent experimental works have shown unexpected spin-dependent electrical properties. The basis for the confection of any spintronic device is ability of selecting the appropriated spin polarization. In this direction, DNA has been pointed out as a potential candidate for spin selection due to the spin-orbit coupling originating from the electric field generated by accumulated electrical charges along the helix. Here, we demonstrate that spin-orbit coupling is the minimum ingredient necessary to promote a spatial spin separation and the generation of spin-current. We show that the up and down spin components have different velocities that give rise to a spin-current. By using a simple situation where spin-orbit coupling is present, we provide qualitative justifications to our results that clearly point to helicoidal molecules as serious candidates to integrate spintronic devices. PMID:27009836

  10. Computerized tomography using video recorded fluoroscopic images

    NASA Technical Reports Server (NTRS)

    Kak, A. C.; Jakowatz, C. V., Jr.; Baily, N. A.; Keller, R. A.

    1977-01-01

    The use of video-recorded fluoroscopic images as input data for digital reconstruction of objects from their projections is examined. The fluoroscopic and the scanning apparatus used for the experiments are of a commercial type already in existence in most hospitals. It is shown that for beams with divergence up to about 15 deg, one can use a convolution algorithm designed for the parallel radiation case with negligible degradation both quantitatively and from a visual quality standpoint. This convolution algorithm is computationally more efficient than either the algebraic techniques or the convolution algorithms for radially diverging data. Results from studies on Lucite phantoms and a freshly sacrificed rat are included.

  11. Modified Involute Helical Gears: Computerized Design, Simulation of Meshing, and Stress Analysis

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert (Technical Monitor); Litvin, Faydor L.; Gonzalez-Perez, Ignacio; Carnevali, Luca; Kawasaki, Kazumasa; Fuentes-Aznar, Alfonso

    2003-01-01

    The computerized design, methods for generation, simulation of meshing, and enhanced stress analysis of modified involute helical gears is presented. The approaches proposed for modification of conventional involute helical gears are based on conjugation of double-crowned pinion with a conventional helical involute gear. Double-crowning of the pinion means deviation of cross-profile from an involute one and deviation in longitudinal direction from a helicoid surface. Using the method developed, the pinion-gear tooth surfaces are in point-contact, the bearing contact is localized and oriented longitudinally, and edge contact is avoided. Also, the influence of errors of aligment on the shift of bearing contact, vibration, and noise are reduced substantially. The theory developed is illustrated with numerical examples that confirm the advantages of the gear drives of the modified geometry in comparison with conventional helical involute gears.

  12. Modified Involute Helical Gears: Computerized Design, Simulation of Meshing and Stress Analysis

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The computerized design, methods for generation, simulation of meshing, and enhanced stress analysis of modified involute helical gears is presented. The approaches proposed for modification of conventional involute helical gears are based on conjugation of double-crowned pinion with a conventional helical involute gear. Double-crowning of the pinion means deviation of cross-profile from an involute one and deviation in longitudinal direction from a helicoid surface. Using the method developed, the pinion-gear tooth surfaces are in point-contact, the bearing contact is localized and oriented longitudinally, and edge contact is avoided. Also, the influence of errors of alignment on the shift of bearing contact, vibration, and noise are reduced substantially. The theory developed is illustrated with numerical examples that confirm the advantages of the gear drives of the modified geometry in comparison with conventional helical involute gears.

  13. Comment on ``Dirac equation in the background of the Nutku helicoid metric'' [J. Math. Phys. 48, 092301 (2007)

    NASA Astrophysics Data System (ADS)

    Birkandan, T.; Hortaçsu, M.

    2008-05-01

    The Dirac equation written on the boundary of the Nutku helicoid space consists of a system of ordinary differential equations. We tried to analyze this system and we found that it has a higher singularity than those of the Heun equations which give the solutions of the Dirac equation in the bulk. We also lose an independent integral of motion on the boundary. This facts explain why we could not find the solution of the system on the boundary in terms of known functions. We make the stability analysis of the helicoid and catenoid cases and end up with an Appendix which gives a new example wherein one encounters a form of the Heun equation.

  14. Comment on 'Dirac equation in the background of the Nutku helicoid metric' [J. Math. Phys. 48, 092301 (2007)

    SciTech Connect

    Birkandan, T.; Hortacsu, M.

    2008-05-15

    The Dirac equation written on the boundary of the Nutku helicoid space consists of a system of ordinary differential equations. We tried to analyze this system and we found that it has a higher singularity than those of the Heun equations which give the solutions of the Dirac equation in the bulk. We also lose an independent integral of motion on the boundary. This facts explain why we could not find the solution of the system on the boundary in terms of known functions. We make the stability analysis of the helicoid and catenoid cases and end up with an Appendix which gives a new example wherein one encounters a form of the Heun equation.

  15. Modulational instability and localized breather modes in the discrete nonlinear Schrödinger equation with helicoidal hopping

    NASA Astrophysics Data System (ADS)

    Stockhofe, J.; Schmelcher, P.

    2016-08-01

    We study a one-dimensional discrete nonlinear Schrödinger model with hopping to the first and a selected Nth neighbor, motivated by a helicoidal arrangement of lattice sites. We provide a detailed analysis of the modulational instability properties of this equation, identifying distinctive multi-stage instability cascades due to the helicoidal hopping term. Bistability is a characteristic feature of the intrinsically localized breather modes, and it is shown that information on the stability properties of weakly localized solutions can be inferred from the plane-wave modulational instability results. Based on this argument, we derive analytical estimates of the critical parameters at which the fundamental on-site breather branch of solutions turns unstable. In the limit of large N, these estimates predict the emergence of an effective threshold behavior, which can be viewed as the result of a dimensional crossover to a two-dimensional square lattice.

  16. Nano-solenoid: helicoid carbon-boron nitride hetero-nanotube

    NASA Astrophysics Data System (ADS)

    Zhang, Zi-Yue; Miao, Chunyang; Guo, Wanlin

    2013-11-01

    As a fundamental element of a nanoscale passive circuit, a nano-inductor is proposed based on a hetero-nanotube consisting of a spiral carbon strip and a spiral boron nitride strip. It is shown by density functional theory associated with nonequilibrium Green function calculations that the nanotube exhibits attractive transport properties tunable by tube chirality, diameter, component proportion and connection manner between the two strips, with excellent `OFF' state performance and high current on the order of 10-100 μA. All the hetero-nanotubes show negative differential resistance. The transmission peaks of current are absolutely derived from the helicoid carbon strips or C-BN boundaries, giving rise to a spiral current analogous with an energized nano-solenoid. According to Ampere's Law, the energized nano-solenoid can generate a uniform and tremendous magnetic field of more than 1 tesla, closing to that generated by the main magnet of medical nuclear magnetic resonance. Moreover, the magnitude of magnetic field can be easily modulated by bias voltage, providing great promise for a nano-inductor to realize electromagnetic conversion at the nanoscale.As a fundamental element of a nanoscale passive circuit, a nano-inductor is proposed based on a hetero-nanotube consisting of a spiral carbon strip and a spiral boron nitride strip. It is shown by density functional theory associated with nonequilibrium Green function calculations that the nanotube exhibits attractive transport properties tunable by tube chirality, diameter, component proportion and connection manner between the two strips, with excellent `OFF' state performance and high current on the order of 10-100 μA. All the hetero-nanotubes show negative differential resistance. The transmission peaks of current are absolutely derived from the helicoid carbon strips or C-BN boundaries, giving rise to a spiral current analogous with an energized nano-solenoid. According to Ampere's Law, the energized nano

  17. The History Computerization Project.

    ERIC Educational Resources Information Center

    Clark, David L.

    1992-01-01

    Description of the History Computerization Project, which is being developed for the exchange of information between researchers, librarians, archivists, museum curators, preservation groups, and historical societies, focuses on workshops that teach the use of computer database management for historical cataloging and research. (LRW)

  18. Computerized Drug Information Services

    ERIC Educational Resources Information Center

    And Others; Smith, Daniel R.

    1972-01-01

    To compare computerized services in chemistry, pharmacology, toxicology, and clinical medicine of pharmaceutical interest, equivalent profiles were run on magnetic tape files of CA-Condensates," CBAC," Excerpta Medica," MEDLARS" and Ringdoc." The results are tabulated for overlap of services, relative speed of citing references, and unique…

  19. Seismic Computerized Alert Network

    USGS Publications Warehouse

    1986-01-01

    In 1985 the USGS devised a model for a Seismic Computerized Alert Network (SCAN) that would use continuous monitoring of seismic data from existing types of instruments to provide automatic, highly-reliable early warnings of earthquake shaking. In a large earthquake, substantial damaging ground motions may occur at great distances from the earthquake's epicenter.

  20. Computerized Fleet Maintenance.

    ERIC Educational Resources Information Center

    Cataldo, John J.

    The computerization of school bus maintenance records by the Niskayuna (New York) Central School District enabled the district's transportation department to engage in management practices resulting in significant savings. The district obtains computer analyses of the work performed on all vehicles, including time spent, parts, labor, costs,…

  1. Adaptive Computerized Instruction.

    ERIC Educational Resources Information Center

    Ray, Roger D.; And Others

    1995-01-01

    Describes an artificially intelligent multimedia computerized instruction system capable of developing a conceptual image of what a student is learning while the student is learning it. It focuses on principles of learning and adaptive behavioral control systems theory upon which the system is designed and demonstrates multiple user modes.…

  2. Transformations and algorithms in a computerized brain atlas

    SciTech Connect

    Thurfjell, L. . Centre for Image Analysis); Bohm, C. . Dept. of Physics); Eriksson, L. . Dept. of Neuroradiology Karolinska Institute/Hospital, Stockholm . Dept of Clinical Neurophysiology)

    1993-08-01

    The computerized brain atlas constructed at the Karolinska Hospital, Stockholm, Sweden, has been further developed. This atlas was designed to be employed in different fields of neuro imaging such as positron emission tomography (PET), single photon emission tomography (SPECT), computerized tomography (CT) and magnetic resonance imaging (MR). The main objectives with the atlas is to aid the interpretation of functional images by introducing anatomical information, to serve as a tool in the merging of data from different imaging modalities and to facilitate the comparisons of data from different individuals by allowing for anatomical standardization of individual data. The purpose of this paper is to describe the algorithms and transformations used in the implementation of the atlas software.

  3. Reversal of helicoidal twist handedness near point defects of confined chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Ackerman, Paul J.; Smalyukh, Ivan I.

    2016-05-01

    Handedness of the director twist in cholesteric liquid crystals is commonly assumed to be the same throughout the medium, determined solely by the chirality of constituent molecules or chiral additives, albeit distortions of the ground-state helicoidal configuration often arise due to the effects of confinement and external fields. We directly probe the twist directionality of liquid crystal director structures through experimental three-dimensional imaging and numerical minimization of the elastic free energy and show that spatially localized regions of handedness opposite to that of the chiral liquid crystal ground state can arise in the proximity of twisted-soliton-bound topological point defects. In chiral nematic liquid crystal confined to a film that has a thickness less than the cholesteric pitch and perpendicular surface boundary conditions, twisted solitonic structures embedded in a uniform unwound far-field background with chirality-matched handedness locally relieve confinement-imposed frustration and tend to be accompanied by point defects and smaller geometry-required, energetically costly regions of opposite twist handedness. We also describe a spatially localized structure, dubbed a "twistion," in which a twisted solitonic three-dimensional director configuration is accompanied by four point defects. We discuss how our findings may impinge on the stability of localized particlelike director field configurations in chiral and nonchiral liquid crystals.

  4. Nuclear magnetic resonance in magnets with a helicoidal magnetic structure in an external magnetic field

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Borich, M. A.; Smagin, V. V.

    2014-11-01

    In this review, the static and dynamic properties of a magnet with a helicoidal magnetic structure placed in an external magnetic field are discussed. The results of the investigation of its ground state and spectra, as well as the amplitudes of the spin excitations are presented. The temperature and field dependences of the basic thermodynamic characteristics (heat capacity, magnetization, and magnetic susceptibility) have been calculated in the spin-wave approximation. The results of calculating the local and integral dynamic magnetic susceptibility are given. This set of data represents a methodical basis for constructing a consistent (in the framework of unified approximations) picture of the NMR absorption in the magnet under consideration. Both local NMR characteristics (resonance frequency, line broadening, enhancement coefficient) and integral characteristics (resultant shape of the absorption line with its specific features) have been calculated. The effective Hamiltonian of the Suhl-Nakamura interaction of nuclear spins through spin waves has been constructed. The second moment and the local broadening of the line of the NMR absorption caused by this interaction have been calculated. The role of the basic local inhomogeneities in the formation of the integral line of the NMR absorption has been analyzed. The opportunities for the experimental NMR investigations in magnets with a chiral spin structure are discussed.

  5. Computerizing Audit Studies

    PubMed Central

    Lahey, Joanna N.; Beasley, Ryan A.

    2014-01-01

    This paper briefly discusses the history, benefits, and shortcomings of traditional audit field experiments to study market discrimination. Specifically it identifies template bias and experimenter bias as major concerns in the traditional audit method, and demonstrates through an empirical example that computerization of a resume or correspondence audit can efficiently increase sample size and greatly mitigate these concerns. Finally, it presents a useful meta-tool that future researchers can use to create their own resume audits. PMID:24904189

  6. Computerized leak training

    SciTech Connect

    Parella, C.; Monroe, A.

    1985-11-01

    Niagara Mohawk Power Corporation's computerized leak detection training system is discussed. The system is able to simulate gas leak situations by means of a computer. The training setup includes actual visual display via slides of houses represented on a plotting board; computer with plotter board in front that simulates an area and various leakage situations; a typical handheld CGI; and a control pad for the computer. The training system has filled a valuable need in the area of emergency training.

  7. Computerized design of CAD

    NASA Astrophysics Data System (ADS)

    Paul, B. E.; Pham, T. A.

    1982-11-01

    A computerized ballistic design technique for CAD/PAD is described by which a set of ballistic design parameters are determined, all of which satisfy a particular performance requirement. In addition, the program yields the remaining performance predictions, so that only a very few computer runs of the design program can quickly bring the ballistic design within the specification limits prescribed. An example is presented for a small propulsion device, such as a remover or actuator, for which the input specifications define a maximum allowable thrust and minimum end-of-stroke velocity. The resulting output automatically satisfies the input requirements, and will always yield an acceptable ballistic design.

  8. Computerized procedures system

    DOEpatents

    Lipner, Melvin H.; Mundy, Roger A.; Franusich, Michael D.

    2010-10-12

    An online data driven computerized procedures system that guides an operator through a complex process facility's operating procedures. The system monitors plant data, processes the data and then, based upon this processing, presents the status of the current procedure step and/or substep to the operator. The system supports multiple users and a single procedure definition supports several interface formats that can be tailored to the individual user. Layered security controls access privileges and revisions are version controlled. The procedures run on a server that is platform independent of the user workstations that the server interfaces with and the user interface supports diverse procedural views.

  9. Role of boundary conditions in helicoidal flow collimation: Consequences for the von Kármán sodium dynamo experiment

    NASA Astrophysics Data System (ADS)

    Varela, J.; Brun, S.; Dubrulle, B.; Nore, C.

    2015-12-01

    We present hydrodynamic and magnetohydrodynamic (MHD) simulations of liquid sodium flow with the PLUTO compressible MHD code to investigate influence of magnetic boundary conditions on the collimation of helicoidal motions. We use a simplified cartesian geometry to represent the flow dynamics in the vicinity of one cavity of a multiblades impeller inspired by those used in the Von-Kármán-sodium (VKS) experiment. We show that the impinging of the large-scale flow upon the impeller generates a coherent helicoidal vortex inside the blades, located at a distance from the upstream blade piloted by the incident angle of the flow. This vortex collimates any existing magnetic field lines leading to an enhancement of the radial magnetic field that is stronger for ferromagnetic than for conducting blades. The induced magnetic field modifies locally the velocity fluctuations, resulting in an enhanced helicity. This process possibly explains why dynamo action is more easily triggered in the VKS experiment when using soft iron impellers.

  10. Role of boundary conditions in helicoidal flow collimation: Consequences for the von Kármán sodium dynamo experiment.

    PubMed

    Varela, J; Brun, S; Dubrulle, B; Nore, C

    2015-12-01

    We present hydrodynamic and magnetohydrodynamic (MHD) simulations of liquid sodium flow with the PLUTO compressible MHD code to investigate influence of magnetic boundary conditions on the collimation of helicoidal motions. We use a simplified cartesian geometry to represent the flow dynamics in the vicinity of one cavity of a multiblades impeller inspired by those used in the Von-Kármán-sodium (VKS) experiment. We show that the impinging of the large-scale flow upon the impeller generates a coherent helicoidal vortex inside the blades, located at a distance from the upstream blade piloted by the incident angle of the flow. This vortex collimates any existing magnetic field lines leading to an enhancement of the radial magnetic field that is stronger for ferromagnetic than for conducting blades. The induced magnetic field modifies locally the velocity fluctuations, resulting in an enhanced helicity. This process possibly explains why dynamo action is more easily triggered in the VKS experiment when using soft iron impellers. PMID:26764812

  11. Computerized Placement Tests: Background Readings.

    ERIC Educational Resources Information Center

    College Entrance Examination Board, Princeton, NJ.

    This document is a compilation of background readings for the user of Computerized Placement Tests (CPTs) developed by the College Board for student placement purposes. CPTs are computerized adaptive tests that test the individual abilities and backgrounds of examinees. CPTs are part of the ACCUPLACER student information management system. The…

  12. Computerized Numerical Control Curriculum Guide.

    ERIC Educational Resources Information Center

    Reneau, Fred; And Others

    This guide is intended for use in a course in programming and operating a computerized numerical control system. Addressed in the course are various aspects of programming and planning, setting up, and operating machines with computerized numerical control, including selecting manual or computer-assigned programs and matching them with…

  13. Computerized training management system

    DOEpatents

    Rice, H.B.; McNair, R.C.; White, K.; Maugeri, T.

    1998-08-04

    A Computerized Training Management System (CTMS) is disclosed for providing a procedurally defined process that is employed to develop accreditable performance based training programs for job classifications that are sensitive to documented regulations and technical information. CTMS is a database that links information needed to maintain a five-phase approach to training-analysis, design, development, implementation, and evaluation independent of training program design. CTMS is designed using R-Base{trademark}, an-SQL compliant software platform. Information is logically entered and linked in CTMS. Each task is linked directly to a performance objective, which, in turn, is linked directly to a learning objective; then, each enabling objective is linked to its respective test items. In addition, tasks, performance objectives, enabling objectives, and test items are linked to their associated reference documents. CTMS keeps all information up to date since it automatically sorts, files and links all data; CTMS includes key word and reference document searches. 18 figs.

  14. Computerized training management system

    DOEpatents

    Rice, Harold B.; McNair, Robert C.; White, Kenneth; Maugeri, Terry

    1998-08-04

    A Computerized Training Management System (CTMS) for providing a procedurally defined process that is employed to develop accreditable performance based training programs for job classifications that are sensitive to documented regulations and technical information. CTMS is a database that links information needed to maintain a five-phase approach to training-analysis, design, development, implementation, and evaluation independent of training program design. CTMS is designed using R-Base.RTM., an-SQL compliant software platform. Information is logically entered and linked in CTMS. Each task is linked directly to a performance objective, which, in turn, is linked directly to a learning objective; then, each enabling objective is linked to its respective test items. In addition, tasks, performance objectives, enabling objectives, and test items are linked to their associated reference documents. CTMS keeps all information up to date since it automatically sorts, files and links all data; CTMS includes key word and reference document searches.

  15. Computerized Measuring Microscope

    NASA Astrophysics Data System (ADS)

    Schoonmaker, Thomas D.

    1980-05-01

    In the manufacturing of printed circuit boards, microscopic analysis is an essential process control activity. An inspector microscopically analyzes board samples to deter-mine board lot quality and process conditions. Prior to computerizing, this sustained measurement-taking involved the tedious process of recording raw data, converting microscope filar readings, calculating averages, logging information in a job notebook, and completing detailed final lab reports. It is evident from this brief task description that this time-consuming repetitious data recording routine was an added burden to the already fatiguing visual inspection method and therefore was a prime candidate for automatic data capture and printout. Secondly, the creation of a permanent and easily accessible data base would improve process feedback and provide for a system with quick identification of any suspect boards if further assembly/testing exhibited board-related failures. This paper describes the evolution and implementation of a computer-aided microscopic inspection operation.

  16. Computerized Physician Order Entry

    PubMed Central

    Khanna, Raman; Yen, Tony

    2014-01-01

    Computerized physician order entry (CPOE) has been promoted as an important component of patient safety, quality improvement, and modernization of medical practice. In practice, however, CPOE affects health care delivery in complex ways, with benefits as well as risks. Every implementation of CPOE is associated with both generally recognized and unique local factors that can facilitate or confound its rollout, and neurohospitalists will often be at the forefront of such rollouts. In this article, we review the literature on CPOE, beginning with definitions and proceeding to comparisons to the standard of care. We then proceed to discuss clinical decision support systems, negative aspects of CPOE, and cultural context of CPOE implementation. Before concluding, we follow the experiences of a Chief Medical Information Officer and neurohospitalist who rolled out a CPOE system at his own health care organization and managed the resulting workflow changes and setbacks. PMID:24381708

  17. Computerizing natural history collections.

    PubMed

    Sunderland, Mary E

    2013-09-01

    Computers are ubiquitous in the life sciences and are associated with many of the practical and conceptual changes that characterize biology's twentieth-century transformation. Yet comparatively little has been written about how scientists use computers. Despite this relative lack of scholarly attention, the claim that computers revolutionized the life sciences by making the impossible possible is widespread, and relatively unchallenged. How did the introduction of computers into research programs shape scientific practice? The Museum of Vertebrate Zoology (MVZ) at the University of California, Berkeley provides a tractable way into this under-examined question because it is possible to follow the computerization of data in the context of long-term research programs. PMID:23664113

  18. Computed Tomography Status

    DOE R&D Accomplishments Database

    Hansche, B. D.

    1983-01-01

    Computed tomography (CT) is a relatively new radiographic technique which has become widely used in the medical field, where it is better known as computerized axial tomographic (CAT) scanning. This technique is also being adopted by the industrial radiographic community, although the greater range of densities, variation in samples sizes, plus possible requirement for finer resolution make it difficult to duplicate the excellent results that the medical scanners have achieved.

  19. Computed tomography status

    SciTech Connect

    Hansche, B.D.

    1983-01-01

    Computed tomography (CT) is a relatively new radiographic technique which has become widely used in the medical field, where it is better known as computerized axial tomographic (CAT) scanning. This technique is also being adopted by the industrial radiographic community, although the greater range of densities, variation in samples sizes, plus possible requirement for finer resolution make it difficult to duplicate the excellent results that the medical scanners have achieved.

  20. Computerized molecular modeling of carbohydrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Computerized molecular modleing continues to increase in capability and applicability to carbohydrates. This chapter covers nomenclature and conformational aspects of carbohydrates, perhaps of greater use to carbohydrate-inexperienced computational chemists. Its comments on various methods and studi...

  1. Mapping the locus of atrophia areata, a helicoid peripapillary chorioretinal degeneration with autosomal dominant inheritance, to chromosome 11p15.

    PubMed

    Fossdal, R; Magnússon, L; Weber, J L; Jensson, O

    1995-03-01

    Atrophia areata (AA) is an early onset autosomal dominant helicoid peripapillary chorioretinal degeneration, which was first demonstrated to be hereditary in an Icelandic family. It is characterized by bilateral wing-shaped atrophic areas of the retina, radiating from the optic disk. Primary complaints of affected individuals are due to refractive errors and scotomata associated with myopia which increases with age. A genome linkage search with 112 microsatellite DNA markers resulted in the highest probability of location for AA on chromosome 11. We genotyped 18 polymorphic markers on chromosome 11 and seven showed significant linkage to AA. The markers D11S1323 and D11S902 on 11p15 flank the region encompassing the gene for AA. PMID:7795606

  2. Computerized international geothermal information systems

    SciTech Connect

    Phillips, S.L.; Lawrence, J.D.; Lepman, S.R.

    1980-03-01

    The computerized international geothermal energy information system is reviewed. The review covers establishment of the Italy - United States linked data centers by the NATO Committee on Challenges of Modern Society, through a bilateral agreement, and up to the present time. The result of the information exchange project is given as the bibliographic and numerical data available from the data centers. Recommendations for the exchange of computerized geothermal information at the international level are discussed.

  3. Arkansas' Curriculum Guide. Competency Based Computerized Accounting.

    ERIC Educational Resources Information Center

    Arkansas State Dept. of Education, Little Rock. Div. of Vocational, Technical and Adult Education.

    This guide contains the essential parts of a total curriculum for a one-year secondary-level course in computerized accounting. Addressed in the individual sections of the guide are the following topics: the complete accounting cycle, computer operations for accounting, computerized accounting and general ledgers, computerized accounts payable,…

  4. California's Computerized Pupil Transportation Systems.

    ERIC Educational Resources Information Center

    Edwards, James C.

    1983-01-01

    Traces efforts to develop a statewide plan for computerized school bus fleet operation by means of questionnaires distributed to all 58 county education offices, 7 regional data processing centers, and selected private school bus contractors and school districts. Findings indicate significant potential savings for fleets of 20 or more busses. (JBM)

  5. Computerized Proof Techniques for Undergraduates

    ERIC Educational Resources Information Center

    Smith, Christopher J.; Tefera, Akalu; Zeleke, Aklilu

    2012-01-01

    The use of computer algebra systems such as Maple and Mathematica is becoming increasingly important and widespread in mathematics learning, teaching and research. In this article, we present computerized proof techniques of Gosper, Wilf-Zeilberger and Zeilberger that can be used for enhancing the teaching and learning of topics in discrete…

  6. Student Perceptions of Computerized Tests

    ERIC Educational Resources Information Center

    Pino-Silva, Juan

    2008-01-01

    The challenge to test small groups by means of microcomputers demands appropriate software design and sound test design. To comply with this demand, students' beliefs or perceptions on the advantages and disadvantages of a computerized test were tapped. Overall, self-reported advantages outnumbered disadvantages to a significant degree. This was…

  7. Computerized PET/CT image analysis in the evaluation of tumour response to therapy

    PubMed Central

    Wang, J; Zhang, H H

    2015-01-01

    Current cancer therapy strategy is mostly population based, however, there are large differences in tumour response among patients. It is therefore important for treating physicians to know individual tumour response. In recent years, many studies proposed the use of computerized positron emission tomography/CT image analysis in the evaluation of tumour response. Results showed that computerized analysis overcame some major limitations of current qualitative and semiquantitative analysis and led to improved accuracy. In this review, we summarize these studies in four steps of the analysis: image registration, tumour segmentation, image feature extraction and response evaluation. Future works are proposed and challenges described. PMID:25723599

  8. Clinical applications of computerized thermography

    NASA Technical Reports Server (NTRS)

    Anbar, Michael

    1988-01-01

    Computerized or digital, thermography is a rapidly growing diagnostic imaging modality. It has superseded contact thermography and analog imaging thermography which do not allow effective quantization. Medical applications of digital thermography can be classified in two groups: static and dynamic imaging. They can also be classified into macro thermography (resolution greater than 1 mm) and micro thermography (resolution less than 100 microns). Both modalities allow a thermal resolution of 0.1 C. The diagnostic power of images produced by any of these modalities can be augmented by the use of digital image enhancement and image recognition procedures. Computerized thermography has been applied in neurology, cardiovascular and plastic surgery, rehabilitation and sports medicine, psychiatry, dermatology and ophthalmology. Examples of these applications are shown and their scope and limitations are discussed.

  9. [Computed tomography and cranial paleoanthropology].

    PubMed

    Cabanis, Emmanuel Alain; Badawi-Fayad, Jackie; Iba-Zizen, Marie-Thérèse; Istoc, Adrian; de Lumley, Henry; de Lumley, Marie-Antoinette; Coppens, Yves

    2007-06-01

    Since its invention in 1972, computed tomography (C.T.) has significantly evolved. With the advent of multi-slice detectors (500 times more sensitive than conventional radiography) and high-powered computer programs, medical applications have also improved. CT is now contributing to paleoanthropological research. Its non-destructive nature is the biggest advantage for studying fossil skulls. The second advantage is the possibility of image analysis, storage, and transmission. Potential disadvantages include the possible loss of files and the need to keep up with rapid technological advances. Our experience since the late 1970s, and a recent PhD thesis, led us to describe routine applications of this method. The main contributions of CT to cranial paleoanthropology are five-fold: --Numerical anatomy with rapid acquisition and high spatial resolution (helicoidal and multidetector CT) offering digital storage and stereolithography (3D printing). --Numerical biometry (2D and 3D) can be used to create "normograms" such as the 3D craniofacial reference model used in maxillofacial surgery. --Numerical analysis offers thorough characterization of the specimen and its state of conservation and/or restoration. --From "surrealism" to virtual imaging, anatomical structures can be reconstructed, providing access to hidden or dangerous zones. --The time dimension (4D imaging) confers movement and the possibility for endoscopic simulation and internal navigation (see Iconography). New technical developments will focus on data processing and networking. It remains our duty to deal respectfully with human fossils. PMID:18402165

  10. Computerized accounting methods. Final report

    SciTech Connect

    1994-12-31

    This report summarizes the results of the research performed under the Task Order on computerized accounting methods in a period from 03 August to 31 December 1994. Computerized nuclear material accounting methods are analyzed and evaluated. Selected methods are implemented in a hardware-software complex developed as a prototype of the local network-based CONMIT system. This complex has been put into trial operation for test and evaluation of the selected methods at two selected ``Kurchatov Institute`` Russian Research Center (``KI`` RRC) nuclear facilities. Trial operation is carried out since the beginning of Initial Physical Inventory Taking in these facilities that was performed in November 1994. Operation of CONMIT prototype system was demonstrated in the middle of December 1994. Results of evaluation of CONMIT prototype system features and functioning under real operating conditions are considered. Conclusions are formulated on the ways of further development of computerized nuclear material accounting methods. The most important conclusion is a need to strengthen computer and information security features supported by the operating environment. Security provisions as well as other LANL Client/Server System approaches being developed by Los Alamos National Laboratory are recommended for selection of software and hardware components to be integrated into production version of CONMIT system for KI RRC.

  11. Multiple-energy Techniques in Industrial Computerized Tomography

    DOE R&D Accomplishments Database

    Schneberk, D.; Martz, H.; Azevedo, S.

    1990-08-01

    Considerable effort is being applied to develop multiple-energy industrial CT techniques for materials characterization. Multiple-energy CT can provide reliable estimates of effective Z (Z{sub eff}), weight fraction, and rigorous calculations of absolute density, all at the spatial resolution of the scanner. Currently, a wide variety of techniques exist for CT scanners, but each has certain problems and limitations. Ultimately, the best multi-energy CT technique would combine the qualities of accuracy, reliability, and wide range of application, and would require the smallest number of additional measurements. We have developed techniques for calculating material properties of industrial objects that differ somewhat from currently used methods. In this paper, we present our methods for calculating Z{sub eff}, weight fraction, and density. We begin with the simplest case -- methods for multiple-energy CT using isotopic sources -- and proceed to multiple-energy work with x-ray machine sources. The methods discussed here are illustrated on CT scans of PBX-9502 high explosives, a lexan-aluminum phantom, and a cylinder of glass beads used in a preliminary study to determine if CT can resolve three phases: air, water, and a high-Z oil. In the CT project at LLNL, we have constructed several CT scanners of varying scanning geometries using {gamma}- and x-ray sources. In our research, we employed two of these scanners: pencil-beam CAT for CT data using isotopic sources and video-CAT equipped with an IRT micro-focal x-ray machine source.

  12. Small angle scattering signals for (neutron) computerized tomography

    SciTech Connect

    Strobl, M.; Treimer, W.; Hilger, A.

    2004-07-19

    Small angle neutron scattering is a well-established tool for the determination of microscopic structures in various materials. With the ultrasmall angle neutron scattering technique (USANS), structures with sizes of approximately 50 nm to 50 {mu}m can be resolved by a double crystal diffractometer (DCD). USANS signals recorded with a special DCD were used for tomographic purposes investigating the macroscopic structure of a sample with a maximum resolution of 200 {mu}m. Thereby, macroscopic regions within the sample with different ultrasmall angle scattering properties, i.e., with different microscopic structures, could be imaged by the means of tomographic reconstruction from projections (on a macroscopic scale)

  13. [Computerized tomography of the orbit in Graves' ophthalmopathy. New observations].

    PubMed

    Bagnolesi, P; Cilotti, A; Campassi, C; Lencioni, R; Napoli, V; Bartolozzi, C

    1992-05-01

    In order to evaluate Graves' ophthalmopathy new CT parameters have been introduced such as: the diameters of the five extraocular muscles, the value of their addition, the grade of apical crowding, the enlargement of optic nerve sheaths and of the superior ophthalmic vein, and the anterior displacement of the lacrimal gland. On this subject we report our further experience after reviewing 68 cases in which the new ocular parameters were correlated with altered ocular motility and optic neuropathy. The results confirmed our previous study, dealing with several groups of patients, which at the moment seem to be 2, instead of 3 groups: a) patients with increase in both muscular and fatty tissue (54/68 cases); b) patients with main or exclusive increase in fatty tissue (14/68 cases). Relevant clinical signs were present only in the first group of patients, where the medial, inferior and superior muscles were affected in 53/55, 53/55 and 50/55 cases respectively. A muscle increase by nearly 50% was more frequently found in cases with altered ocular motility, an increase by 90% was often associated with optic neuropathy. In case of optic neuropathy apical crowding was often observed, mainly in coronal scans, together with significant enlargement of the optic nerve sheath and of the superior ophthalmic vein. As to proptosis, preseptal area and anterior displacement of the lacrimal gland, they demonstrated lower correlation with the reference symptoms, even though their occurrence was high in symptomatic patients. PMID:1631331

  14. HELICoiD project: a new use of hyperspectral imaging for brain cancer detection in real-time during neurosurgical operations

    NASA Astrophysics Data System (ADS)

    Fabelo, Himar; Ortega, Samuel; Kabwama, Silvester; Callico, Gustavo M.; Bulters, Diederik; Szolna, Adam; Pineiro, Juan F.; Sarmiento, Roberto

    2016-05-01

    Hyperspectral images allow obtaining large amounts of information about the surface of the scene that is captured by the sensor. Using this information and a set of complex classification algorithms is possible to determine which material or substance is located in each pixel. The HELICoiD (HypErspectraL Imaging Cancer Detection) project is a European FET project that has the goal to develop a demonstrator capable to discriminate, with high precision, between normal and tumour tissues, operating in real-time, during neurosurgical operations. This demonstrator could help the neurosurgeons in the process of brain tumour resection, avoiding the excessive extraction of normal tissue and unintentionally leaving small remnants of tumour. Such precise delimitation of the tumour boundaries will improve the results of the surgery. The HELICoiD demonstrator is composed of two hyperspectral cameras obtained from Headwall. The first one in the spectral range from 400 to 1000 nm (visible and near infrared) and the second one in the spectral range from 900 to 1700 nm (near infrared). The demonstrator also includes an illumination system that covers the spectral range from 400 nm to 2200 nm. A data processing unit is in charge of managing all the parts of the demonstrator, and a high performance platform aims to accelerate the hyperspectral image classification process. Each one of these elements is installed in a customized structure specially designed for surgical environments. Preliminary results of the classification algorithms offer high accuracy (over 95%) in the discrimination between normal and tumour tissues.

  15. Advanced Composition and the Computerized Library.

    ERIC Educational Resources Information Center

    Hult, Christine

    1989-01-01

    Discusses four kinds of computerized access tools: online catalogs; computerized reference; online database searching; and compact disks and read only memory (CD-ROM). Examines how these technologies are changing research. Suggests how research instruction in advanced writing courses can be refocused to include the new technologies. (RS)

  16. Cassel Psych Center Computerized Biofeedback Clinic.

    ERIC Educational Resources Information Center

    Cassel, Russell N.

    1982-01-01

    Describes Cassel Psych Center, a computerized biofeedback clinic, where the "well" patient is a major concern, and where biofeedback instruments are used with computers to form a Computerized-Biofeedback Clinical Support System. The Center's activities are designed to parallel the services of the pathologist in a medical setting. (PAS)

  17. Resources for Improving Computerized Learning Environments.

    ERIC Educational Resources Information Center

    Yeaman, Andrew R. J.

    1989-01-01

    Presents an annotated review of human factors literature that discusses computerized environments. Topics discussed include the application of office automation practices to educational environments; video display terminal (VDT) workstations; health and safety hazards; planning educational facilities; ergonomics in computerized offices; and…

  18. Protecting Privacy in Computerized Medical Information.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. Office of Technology Assessment.

    This report analyzes the implications of computerized medical information and the challenges it brings to individual privacy. The report examines the nature of the privacy interest in health care information and the current state of the law protecting that information; the nature of proposals to computerize health care information and the…

  19. Computerized Classification Testing with the Rasch Model

    ERIC Educational Resources Information Center

    Eggen, Theo J. H. M.

    2011-01-01

    If classification in a limited number of categories is the purpose of testing, computerized adaptive tests (CATs) with algorithms based on sequential statistical testing perform better than estimation-based CATs (e.g., Eggen & Straetmans, 2000). In these computerized classification tests (CCTs), the Sequential Probability Ratio Test (SPRT) (Wald,…

  20. Computerization of the Student Neurophysiology Laboratory.

    ERIC Educational Resources Information Center

    Bishop, Beverly

    1985-01-01

    Describes how a traditional neurophysiology laboratory has been computerized and how students work with digitizing on-line data. Points out advantages of computerization, including the speed, accuracy, and reliability in the acquisition, reduction, and analysis of data. Also describes four generic computer programs tailored to the particular…

  1. Computerized Sociometric Assessment for Preschool Children

    ERIC Educational Resources Information Center

    Endedijk, Hinke M.; Cillessen, Antonius H. N.

    2015-01-01

    In preschool classes, sociometric peer ratings are used to measure children's peer relationships. The current study examined a computerized version of preschool sociometric ratings. The psychometric properties were compared of computerized sociometric ratings and traditional peer ratings for preschoolers. The distributions, inter-item…

  2. A First Life with Computerized Business Simulations

    ERIC Educational Resources Information Center

    Thavikulwat, Precha

    2011-01-01

    The author discusses the theoretical lens, origins, and environment of his work on computerized business simulations. Key ideas that inform his work include the two dimensions (control and interaction) of computerized simulation, the two ways of representing a natural process (phenotypical and genotypical) in a simulation, which he defines as a…

  3. The Computerization of East Asian Languages.

    ERIC Educational Resources Information Center

    Cooper, Douglas W.

    1984-01-01

    Describes two methods for the computerization of Chinese, Japanese, and Korean (CJK) input and output--Research Libraries Group's Sinoterm and OCLC's Asiagraphics. East Asian vernacular computerization efforts, system development, character sets, terminal design and keyboards, and member library use of CJK records are highlighted. Six references…

  4. Computerized Management of Physical Plant Services.

    ERIC Educational Resources Information Center

    Hawkey, Earl W.; Kleinpeter, Joseph

    Outlining the major areas to be considered when deciding whether or not to computerize physical plant services in higher education institutions, the author points out the shortcomings of manual record keeping systems. He gives five factors to consider when deciding to computerize: (1) time and money, (2) extent of operation, (3) current and future…

  5. Computerized Adaptive Testing under Nonparametric IRT Models

    ERIC Educational Resources Information Center

    Xu, Xueli; Douglas, Jeff

    2006-01-01

    Nonparametric item response models have been developed as alternatives to the relatively inflexible parametric item response models. An open question is whether it is possible and practical to administer computerized adaptive testing with nonparametric models. This paper explores the possibility of computerized adaptive testing when using…

  6. The Evaluation of SISMAKOM (Computerized SDI Project).

    ERIC Educational Resources Information Center

    University of Science, Penang (Malaysia).

    A survey of 88 users of SISMAKOM, a computerized selective dissemination of information (SDI) and document delivery service provided by the Universiti Sains Malaysia and four other Malaysian universities, was conducted in August 1982 in order to collect data about SISMAKOM and to assess the value of a computerized SDI service in a developing…

  7. Chlorella vulgaris as a lipid source: Cultivation on air and seawater-simulating medium in a helicoidal photobioreactor.

    PubMed

    Frumento, Davide; Aliakbarian, Bahar; Casazza, Alessandro Alberto; Converti, Attilio; Al Arni, Saleh; da Silva, Milena Fernandes

    2016-03-01

    The freshwater microalga Chlorella vulgaris was cultured batchwise on the seawater-simulating Schlösser medium either in a 1.1-L-working volume helicoidal photobioreactor (HeP) or Erlenmeyer flask (EF) as control and continuously supplying air as CO2 source. In these systems, maximum biomass concentration reached 1.65 ± 0.17 g L(-1) and 1.25 ± 0.06 g L(-1) , and maximum cell productivity 197.6 ± 20.4 mg L(-1)  day(-1) and 160.8 ± 12.2 mg L(-1)  day(-1) , respectively. Compared to the Bold's Basal medium, commonly employed to cultivate this microorganism on a bench-scale, the Schlösser medium ensured significant increases in all the growth parameters, namely maximum cell concentration (268% in EF and 126% in HeP), maximum biomass productivity (554% in EF and 72% in HeP), average specific growth rate (67% in EF and 42% in HeP), and maximum specific growth rate (233% in EF and 22% in HeP). The lipid fraction of biomass collected at the end of runs was analyzed in terms of both lipid content and fatty acid profile. It was found that the seawater-simulating medium, despite of a 56-63% reduction of the overall biomass lipid content compared to the Bold's Basal one, led in HeP to significant increases in both the glycerides-to-total lipid ratio and polyunsaturated fatty acid content compared to the other conditions taken as an average. These results as a whole suggest that the HeP configuration could be a successful alternative to the present means to cultivate C. vulgaris as a lipid source. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:279-284, 2016. PMID:26697953

  8. A computerized obstetric medical record.

    PubMed

    Stead, W W; Brame, R G; Hammond, W E; Jelovsek, F R; Estes, E H; Parker, R T

    1977-04-01

    Duke University has utilized computerized obstetric medical records since 1971. System evolution is described. Deficiencies in the current system appear to evolve from the computer/human interface rather than from basic system design. Critical elements in system success are physician acceptance of the appearance of data collection sheets and printed notes and continual rapid response in programing modification to allow for physician individuality and changes in medical practice. The limiting factor in the potential usefulness of such a system is the rate of incomplete data collection. It is suggested that if the physician were to enter data directly into the computer through a terminal, data collection would be more accurate and complete. PMID:854253

  9. 45 CFR 307.5 - Mandatory computerized support enforcement systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 2 2014-10-01 2012-10-01 true Mandatory computerized support enforcement systems... HEALTH AND HUMAN SERVICES COMPUTERIZED SUPPORT ENFORCEMENT SYSTEMS § 307.5 Mandatory computerized support... operational computerized support enforcement system, which meets Federal requirements under § 302.85(a)(1)...

  10. 45 CFR 307.5 - Mandatory computerized support enforcement systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 2 2013-10-01 2012-10-01 true Mandatory computerized support enforcement systems... HEALTH AND HUMAN SERVICES COMPUTERIZED SUPPORT ENFORCEMENT SYSTEMS § 307.5 Mandatory computerized support... operational computerized support enforcement system, which meets Federal requirements under § 302.85(a)(1)...

  11. 45 CFR 307.5 - Mandatory computerized support enforcement systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 2 2012-10-01 2012-10-01 false Mandatory computerized support enforcement systems... HEALTH AND HUMAN SERVICES COMPUTERIZED SUPPORT ENFORCEMENT SYSTEMS § 307.5 Mandatory computerized support... operational computerized support enforcement system, which meets Federal requirements under § 302.85(a)(1)...

  12. Computerized cash management: the new frontier.

    PubMed

    Grimmelman, F J

    1979-01-01

    Because cash management in a hospital is more complicated today than it was ten years ago, the finanical manager needs a computerized cash management system to help assess cash resources and control cash demands. PMID:10242146

  13. Graphical Models and Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    Almond, Russell G.; Mislevy, Robert J.

    1999-01-01

    Considers computerized adaptive testing from the perspective of graphical modeling (GM). GM provides methods for making inferences about multifaceted skills and knowledge and for extracting data from complex performances. Provides examples from language-proficiency assessment. (SLD)

  14. HUMAN RELIABILITY ANALYSIS FOR COMPUTERIZED PROCEDURES

    SciTech Connect

    Ronald L. Boring; David I. Gertman; Katya Le Blanc

    2011-09-01

    This paper provides a characterization of human reliability analysis (HRA) issues for computerized procedures in nuclear power plant control rooms. It is beyond the scope of this paper to propose a new HRA approach or to recommend specific methods or refinements to those methods. Rather, this paper provides a review of HRA as applied to traditional paper-based procedures, followed by a discussion of what specific factors should additionally be considered in HRAs for computerized procedures. Performance shaping factors and failure modes unique to computerized procedures are highlighted. Since there is no definitive guide to HRA for paper-based procedures, this paper also serves to clarify the existing guidance on paper-based procedures before delving into the unique aspects of computerized procedures.

  15. Computerized Bus Routing in San Francisco.

    ERIC Educational Resources Information Center

    Caswell, Peter J.; Jungherr, J. Anton

    1979-01-01

    A computerized routing and scheduling system for the San Francisco Public Schools includes the batch processing of bus route assignments and schedules for all schools and the online terminal processing of daily changes. (Author/MLF)

  16. The Research on Computerized Adaptive Testing

    NASA Astrophysics Data System (ADS)

    Lu, Peng; Cong, Xiao

    2016-04-01

    In recent years, computerized adaptive testing is becoming the focus of the field of modern educational evaluation. In this form of the test, the response relationship between the examinee with the item by IRT modelling, then use the computer to estimates the ability level of the examinees and real-time select item. Computerized adaptive test development process were reviewed in the paper, and discuss the latest research results and pointed out that the current problems and future trends.

  17. Computerized Mental Status Testing in the Elderly

    PubMed Central

    Slaughter, J.R.; Hesse, B.W.; Turner, C.W.

    1988-01-01

    To assist in the evaluation of the hundreds of thousands of geriatric veterans that will inundate the VA health care system through the latter part of this century and the early part of the next, the authors are applying a computerized mental status screening instrument. The authors have computerized a cognitive and emotive screening instrument aimed primarily at the early detection of dementia and depression, specially adapted to elderly patients.

  18. Computerized Dental Injection Fear Treatment

    PubMed Central

    Heaton, L.J.; Leroux, B.G.; Ruff, P.A.; Coldwell, S.E.

    2013-01-01

    One in four adults reports a clinically significant fear of dental injections, leading many to avoid dental care. While systematic desensitization is the most common therapeutic method for treating specific phobias such as fear of dental injections, lack of access to trained therapists, as well as dentists’ lack of training and time in providing such a therapy, means that most fearful individuals are not able to receive the therapy needed to be able to receive necessary dental treatment. Computer Assisted Relaxation Learning (CARL) is a self-paced computerized treatment based on systematic desensitization for dental injection fear. This multicenter, block-randomized, dentist-blind, parallel-group study conducted in 8 sites in the United States compared CARL with an informational pamphlet in reducing fear of dental injections. Participants completing CARL reported significantly greater reduction in self-reported general and injection-specific dental anxiety measures compared with control individuals (p < .001). Twice as many CARL participants (35.3%) as controls (17.6%) opted to receive a dental injection after the intervention, although this was not statistically significant. CARL, therefore, led to significant changes in self-reported fear in study participants, but no significant differences in the proportion of participants having a dental injection (ClinicalTrials.gov, NCT00609648). PMID:23690352

  19. Computerized provider order entry systems.

    PubMed

    2001-01-01

    Computerized provider order entry (CPOE) systems are designed to replace a hospital's paper-based ordering system. They allow users to electronically write the full range of orders, maintain an online medication administration record, and review changes made to an order by successive personnel. They also offer safety alerts that are triggered when an unsafe order (such as for a duplicate drug therapy) is entered, as well as clinical decision support to guide caregivers to less expensive alternatives or to choices that better fit established hospital protocols. CPOE systems can, when correctly configured, markedly increase efficiency and improve patient safety and patient care. However, facilities need to recognize that currently available CPOE systems require a tremendous amount of time and effort to be spent in customization before their safety and clinical support features can be effectively implemented. What's more, even after they've been customized, the systems may still allow certain unsafe orders to be entered. Thus, CPOE systems are not currently a quick or easy remedy for medical errors. ECRI's Evaluation of CPOE systems--conducted in collaboration with the Institute for Safe Medication Practices (ISMP)--discusses these and other related issues. It also examines and compares CPOE systems from three suppliers: Eclipsys Corp., IDX Systems Corp., and Siemens Medical Solutions Health Services Corp. Our testing focuses primarily on the systems' interfacing capabilities, patient safeguards, and ease of use. PMID:11696968

  20. Computerized Adaptive Personality Testing: A Review and Illustration With the MMPI-2 Computerized Adaptive Version.

    ERIC Educational Resources Information Center

    Forbey, Johnathan D.; Ben-Porath, Yossef S.

    2007-01-01

    Computerized adaptive testing in personality assessment can improve efficiency by significantly reducing the number of items administered to answer an assessment question. Two approaches have been explored for adaptive testing in computerized personality assessment: item response theory and the countdown method. In this article, the authors…

  1. A Computerized Implementation of a Flexilevel Test and Its Comparison with a Bayesian Computerized Adaptive Test.

    ERIC Educational Resources Information Center

    DeAyala, R. J.; Koch, William R.

    A computerized flexilevel test was implemented and its ability estimates were compared with those of a Bayesian estimation based computerized adaptive test (CAT) as well as with known true ability estimates. Results showed that when the flexilevel test was terminated according to Lord's criterion, its ability estimates were highly and…

  2. Computerized microtomography for new applications

    SciTech Connect

    Ice, G.; Thompson, A.

    1996-09-01

    The advent of high brilliance synchrotron sources has stimulated the development of advanced x-ray microtomography. However, materials research problems challenge existing tomographic techniques. High spatial resolution is required to identify and characterize microstructure in real materials. Good elemental sensitivity is required to study the effects of microalloying. Three-dimensional crystal texture, strain and phase information is required to understand advanced materials. Materials samples can include a wide range of elements, can come in unfavorable geometries, and sometimes require dynamic measurements of their three-dimensional structure. One challenge for x-ray microtomography is the measurement of low concentrations with good spatial resolution and high elemental sensitivity. Another challenge to standard x-ray microtomography is the study of elemental distributions in planar structures where elemental sensitivity is required in one or two dimensions, but the spatial sensitivity in all three dimensions is not required. For a large class of materials, crystalline structure, strain and texture are critical to the materials properties. Recent work has now demonstrated the possibility of extending X-ray microdiffraction to the study of three dimensional crystallographic distributions. Efforts are now underway at the APS, ALS, SSRL and NSLS to further develop x-ray microdiffraction and x-ray microdiffraction tomography. The measurement of strain and texture in three dimensions will have important applications to the study of high J{sub c} high {Tc} superconductors, the study of second phase distributions and texture in composite materials, and the study of crack and void evolution in structural and electronic materials. Another frontier for x-ray tomography is the development of dynamic, real-time measurements.

  3. A computerized brain atlas: construction, anatomical content, and some applications.

    PubMed

    Greitz, T; Bohm, C; Holte, S; Eriksson, L

    1991-01-01

    An adjustable computerized atlas of the human brain has been developed, which can be adapted to fit individual anatomy. It is primarily intended for positron emission tomography (PET) but may also be used for single photon emission CT, transmission CT, magnetic resonance imaging, and neuroimaging-based procedures, such as stereotactic surgery and radiotherapy. The atlas is based on anatomical information obtained from brains fixed in situ soon after death. All structures have been drawn in on digitized photos of slices from one cryosectioned brain. The definition and classification of the anatomical structures and divisions are in agreement with the standard textbooks of anatomy, and the nomenclature is that of the Nomina Anatomica of 1965. The boundaries of the cortical cytoarchitectonic areas (Brodmann areas) have been determined using information from several sources, since three-dimensional literature data on their distribution are incomplete, scarce, and partly contradictory. However, no analysis of the cytoarchitectonics of the atlas brain itself has been undertaken. At present the data base contains three-dimensional representations of the brain surface, the ventricular system, the cortical gyri and sulci, as well as the Brodmann cytoarchitectonic areas. The major basal ganglia, the brain stem nuclei, the lobuli of the vermis, and the cerebellar hemispheres are also included. The computerized atlas can be used to improve the quantification and evaluation of PET data in several ways. For instance, it can serve as a guide in selecting regions of interest. It may also facilitate comparisons of data from different individuals or groups of individuals, by applying the inverse atlas transformation to PET data volume, thus relating the PET information to the anatomy of the reference atlas rather than to the patient's anatomy. Reformatted PET data from individuals can thus be averaged, and averages from different categories or different functional states of patients

  4. Evaluation of manual and computerized methods for the determination of axial vertebral rotation

    NASA Astrophysics Data System (ADS)

    Vrtovec, Tomaž; Pernuš, Franjo; Likar, Boštjan

    2010-03-01

    Axial vertebral rotation is among the most important parameters for the evaluation of spinal deformities, and several manual and computerized methods have been proposed for its measurement. Routine manual measurement of axial vertebral rotation from three-dimensional (3D) images is error-prone due to the limitations of the observers, different properties of imaging techniques, variable characteristics of the observed anatomy, and difficulties in image navigation and representation. Computerized methods do not suffer from these limitations and may yield accurate results, however, they also require manual identification of multiple anatomical landmarks or neglect the sagittal and coronal inclinations of vertebrae. The variability of manual and computerized methods for measuring axial vertebral rotation in 3D images has not been thoroughly investigated yet. In this study we evaluated, compared and analyzed four different manual and a computerized method for measuring axial vertebral rotation. Using each method, three observers independently performed two series of manual measurements on 56 normal and scoliotic vertebrae in images, acquired by computed tomography (CT) and magnetic resonance (MR), which allowed the estimation of intra-observer, inter-observer and inter-method variability. The relatively low intra-observer standard deviation (0.8, 0.7 and 1.3 degrees for each observer), inter-observer standard deviation (1.3, 2.0 and 1.9 degrees for each observer pair), and inter-method standard deviation (best: 1.9 degrees) of the computerized method indicate that it is feasible for the determination of axial vertebral rotation and may represent an efficient alternative to manual methods in terms of repeatability, reliability and user effort.

  5. The Construction and Uses of CATIA, a Computerized Mathematics Testbank

    ERIC Educational Resources Information Center

    Burton, Charles R.; Marosz, Wanda A.

    1977-01-01

    Described is the construction of a computerized test bank to generate and score tests in college algebra, trigonometry, and intermediate algebra; including a discussion of uses, advantages and disadvantages of computerized testing. (JLH)

  6. Computed Tomography

    NASA Astrophysics Data System (ADS)

    Castellano, Isabel; Geleijns, Jacob

    After its clinical introduction in 1973, computed tomography developed from an x-ray modality for axial imaging in neuroradiology into a versatile three dimensional imaging modality for a wide range of applications in for example oncology, vascular radiology, cardiology, traumatology and even in interventional radiology. Computed tomography is applied for diagnosis, follow-up studies and screening of healthy subpopulations with specific risk factors. This chapter provides a general introduction in computed tomography, covering a short history of computed tomography, technology, image quality, dosimetry, room shielding, quality control and quality criteria.

  7. 39 CFR 501.15 - Computerized Meter Resetting System.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Computerized Meter Resetting System. 501.15... AND DISTRIBUTE POSTAGE EVIDENCING SYSTEMS § 501.15 Computerized Meter Resetting System. (a) Description. The Computerized Meter Resetting System (CMRS) permits customers to reset their postage meters...

  8. 39 CFR 501.15 - Computerized Meter Resetting System.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Computerized Meter Resetting System. 501.15... AND DISTRIBUTE POSTAGE EVIDENCING SYSTEMS § 501.15 Computerized Meter Resetting System. (a) Description. The Computerized Meter Resetting System (CMRS) permits customers to reset their postage meters...

  9. 39 CFR 501.15 - Computerized Meter Resetting System.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Computerized Meter Resetting System. 501.15... AND DISTRIBUTE POSTAGE EVIDENCING SYSTEMS § 501.15 Computerized Meter Resetting System. (a) Description. The Computerized Meter Resetting System (CMRS) permits customers to reset their postage meters...

  10. 39 CFR 501.15 - Computerized Meter Resetting System.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Computerized Meter Resetting System. 501.15... AND DISTRIBUTE POSTAGE EVIDENCING SYSTEMS § 501.15 Computerized Meter Resetting System. (a) Description. The Computerized Meter Resetting System (CMRS) permits customers to reset their postage meters...

  11. A Computerized Adaptive Edition of the Differential Aptitude Tests.

    ERIC Educational Resources Information Center

    McBride, James R.

    An overview of the development of a computerized version of the Differential Aptitude Tests (DAT) is presented. It describes the previously existing printed version of the DAT, design of the computerized adaptive edition, calibration of the test items for use in the computerized version, and two field studies that compared the Adaptive and…

  12. Computerized Financial Reporting Based on GAAP.

    ERIC Educational Resources Information Center

    Tikkanen, Stan; Liljeberg, Burt

    1983-01-01

    Describes the statewide computerized system developed in Minnesota following the 1976 enactment of the Uniform Financial Accounting and Reporting Standards (UFARS) law. UFARS includes provisions for an advisory council responsible for recommending accounting and reporting procedures, and seven data processing centers to serve all 560 Minnesota…

  13. Implementation of a Computerized Maintenance Management System

    NASA Technical Reports Server (NTRS)

    Shen, Yong-Hong; Askari, Bruce

    1994-01-01

    A primer Computerized Maintenance Management System (CMMS) has been established for NASA Ames pressure component certification program. The CMMS takes full advantage of the latest computer technology and SQL relational database to perform periodic services for vital pressure components. The Ames certification program is briefly described and the aspects of the CMMS implementation are discussed as they are related to the certification objectives.

  14. Individual Differences in Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    Kim, JinGyu

    Research on the major computerized adaptive testing (CAT) strategies is reviewed, and some findings are reported that examine effects of examinee demographic and psychological characteristics on CAT strategies. In fixed branching strategies, all examinees respond to a common routing test, the score of which is used to assign examinees to a…

  15. Computerized Symbol Processing for Handicapped Persons.

    ERIC Educational Resources Information Center

    Osguthorpe, Russell T.; And Others

    The paper describes the development of a computerized symbol processing system which allows nonspeaking severely handicapped persons to create communication electronically. Two pilot studies investigated the use of Rebus and Bliss Symbols with either an Apple Graphics Tablet or the Power Pad, a peripheral which allowed users to activate the…

  16. Issues in Computerized Communication: Components and Questions.

    ERIC Educational Resources Information Center

    Travis, Gregory Reed

    1992-01-01

    Discusses the growth of computerized communications. Attributes this growth to rapid growth of the computer industry, price reductions on computer equipment, and university installation of departmental computers. Describes the Internet, USENET, and electronic mail. Concludes that individuals must be trained to use, understand, and participate in…

  17. Item Selection in Computerized Classification Testing

    ERIC Educational Resources Information Center

    Thompson, Nathan A.

    2009-01-01

    Several alternatives for item selection algorithms based on item response theory in computerized classification testing (CCT) have been suggested, with no conclusive evidence on the substantial superiority of a single method. It is argued that the lack of sizable effect is because some of the methods actually assess items very similarly through…

  18. Principles for Creating a Computerized Test Battery.

    ERIC Educational Resources Information Center

    Kyllonen, Patrick C.

    1991-01-01

    The experience of developing a set of comprehensive aptitude batteries for computer administration for the Air Force Human Resources Laboratory's Learning Abilities Measurement Program resulted in the formulation of nine principles for creation of a computerized test battery. These principles are discussed in the context of research on…

  19. Computerized Mastery Testing with Nonequivalent Testlets.

    ERIC Educational Resources Information Center

    Sheehan, Kathleen; Lewis, Charles

    1992-01-01

    A procedure is introduced for determining the effect of testlet nonequivalence on operating characteristics of a testlet-based computerized mastery test (CMT). The procedure, which involves estimating the CMT decision rule twice with testlet likelihoods treated as equivalent or nonequivalent, is demonstrated with testlet pools from the Architect…

  20. An Introduction to the Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Tian, Jian-quan; Miao, Dan-min; Zhu, Xia; Gong, Jing-jing

    2007-01-01

    Computerized adaptive testing (CAT) has unsurpassable advantages over traditional testing. It has become the mainstream in large scale examinations in modern society. This paper gives a brief introduction to CAT including differences between traditional testing and CAT, the principles of CAT, psychometric theory and computer algorithms of CAT, the…

  1. Computerized system for measuring cerebral metabolism

    SciTech Connect

    McGlone, J.S.; Hibbard, L.S.; Hawkins, R.A.; Kasturi, R.

    1987-09-01

    A computerized stereotactic measurement system for evaluating rat brain metabolism was developed to utilize the large amount of data generated by quantitative autoradiography. Conventional methods of measurement only analyze a small percent of these data because these methods are limited by instrument design and the subjectiveness of the investigator. However, a computerized system allows digital images to be analyzed by placing data at their appropriate three-dimensional stereotactic coordinates. The system automatically registers experimental data to a standard three-dimensional image using alignment, scaling, and matching operations. Metabolic activity in different neuronal structures is then measured by generating digital masks and superimposing them on to experimental data. Several experimental data sets were evaluated and it was noticed that the structures measured by the computerized system, had in general, lower metabolic activity than manual measurements had indicated. This was expected because the computerized system measured the structure over its volume while the manual readings were taken from the most active metabolic area of a particular structure.

  2. Evaluating Content Alignment in Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Wise, Steven L.; Kingsbury, G. Gage; Webb, Norman L.

    2015-01-01

    The alignment between a test and the content domain it measures represents key evidence for the validation of test score inferences. Although procedures have been developed for evaluating the content alignment of linear tests, these procedures are not readily applicable to computerized adaptive tests (CATs), which require large item pools and do…

  3. MU's Early Space-Planning Computerization.

    ERIC Educational Resources Information Center

    Shader, Scott; Vaughn, Anthony

    1998-01-01

    Discusses the development of the University of Missouri-Columbia's Space Planning and Management office (SPAM) and the computerization of the school's space-planning archives. Discusses SPAM's software selection for standardization as well as its manual development, placing the school's buildings and floor plans on the Web, and its space-modeling…

  4. NATIONAL ARCHIVE OF COMPUTERIZED DATA ON AGING

    EPA Science Inventory

    The National Archive of Computerized Data on Aging (NACDA), located within ICPSR, is funded by the National Institute on Aging. NACDA's mission is to advance research on aging by helping researchers to profit from the under-exploited potential of a broad range of datasets. NACDA ...

  5. The Computerized Adaptive Testing System Development Project.

    ERIC Educational Resources Information Center

    McBride, James R.; Sympson, J. B.

    The Computerized Adaptive Testing (CAT) project is a joint Armed Services coordinated effort to develop and evaluate a system for automated, adaptive administration of the Armed Services Vocational Aptitude Battery (ASVAB). The CAT is a system for administering personnel tests that differs from conventional test administration in two major…

  6. 36 CFR 1120.52 - Computerized records.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... additional programming of the computer, thus producing information not previously in being, is not required... from the computer which permits copying the printout, the material will be made available at the per... information from computerized records frequently involves a minimum computer time cost of approximately...

  7. MMI Preparatory School Computerized Model Library.

    ERIC Educational Resources Information Center

    Everhart, Nancy

    This booklet provides a detailed description of the computerization of the library of MMI Preparatory School, a private, non-sectarian college preparatory school in Pennsylvania for students in grades 7 through 12. Each of the following functions is investigated: (1) catalog card production; (2) online reference services; (3) circulation; (4) word…

  8. Computerized management information systems and organizational structures

    NASA Technical Reports Server (NTRS)

    Zannetos, Z. S.; Sertel, M. R.

    1970-01-01

    The computerized management of information systems and organizational structures is discussed. The subjects presented are: (1) critical factors favoring centralization and decentralization of organizations, (2) classification of organizations by relative structure, (3) attempts to measure change in organization structure, and (4) impact of information technology developments on organizational structure changes.

  9. Computerized Enrollment Driven Financial Forecasting Model.

    ERIC Educational Resources Information Center

    Sarvella, John R.

    An interactive, computerized model developed for Old Dominion University utilizes university historical data, demographic characteristics, projected selected economic variables and population figures by various age groups and planning districts to forecast enrollment, financial projections, and future fiscal conditions of the institution. The…

  10. Computerizing Maintenance Management Improves School Processes.

    ERIC Educational Resources Information Center

    Conroy, Pat

    2002-01-01

    Describes how a Computerized Maintenance Management System (CMMS), a centralized maintenance operations database that facilitates work order procedures and staff directives, can help individual school campuses and school districts to manage maintenance. Presents the benefits of CMMS and things to consider in CMMS selection. (EV)

  11. Computerized Adaptive Mastery Tests as Expert Systems.

    ERIC Educational Resources Information Center

    Frick, Theodore W.

    1992-01-01

    Discussion of expert systems and computerized adaptive tests describes two versions of EXSPRT, a new approach that combines uncertain inference in expert systems with sequential probability ratio test (SPRT) stopping rules. Results of two studies comparing EXSPRT to adaptive mastery testing based on item response theory and SPRT approaches are…

  12. Computerized Inspection Of Gear-Tooth Surfaces

    NASA Technical Reports Server (NTRS)

    Handschuh, R. F.; Litvin, F. L.; Zhang, Y.; Kuan, C.

    1994-01-01

    Method of manufacturing gears with precisely shaped teeth involves computerized inspection of gear-tooth surfaces followed by adjustments of machine-tool settings to minimize deviations between real and theoretical versions of surfaces. Thus, iterated cycles of cutting gear teeth, inspection, and adjustments help increase and/or maintain precision of subsequently manufactured gears.

  13. Termination Criteria for Computerized Classification Testing

    ERIC Educational Resources Information Center

    Thompson, Nathan A.

    2011-01-01

    Computerized classification testing (CCT) is an approach to designing tests with intelligent algorithms, similar to adaptive testing, but specifically designed for the purpose of classifying examinees into categories such as "pass" and "fail." Like adaptive testing for point estimation of ability, the key component is the termination criterion,…

  14. Computerized Grading of Anatomy Laboratory Practical Examinations

    ERIC Educational Resources Information Center

    Krippendorf, Beth B.; Bolender, David L.; Kolesari, Gary L.

    2008-01-01

    At the Medical College of Wisconsin, a procedure was developed to allow computerized grading and grade reporting of laboratory practical examinations in the Clinical Human Anatomy course. At the start of the course, first year medical students were given four Lists of Structures. On these lists, numbered items were arranged alphabetically; the…

  15. Special Education Curriculum (Computerized IEP Catalog).

    ERIC Educational Resources Information Center

    Garland Independent School District, TX.

    This special education curriculum, developed by the Garland (Texas) Independent School District, outlines the basic tools for preparing an Individual Educational Plan (IEP) for each handicapped student. The curricular information is organized and coded to facilitate computerized printing of the IEP. The document begins with a list of 13…

  16. The Four Generations of Computerized Educational Measurement.

    ERIC Educational Resources Information Center

    Bunderson, C. Victor; And Others

    Educational measurement is undergoing a revolution due to the rapid dissemination of information-processing technology. The recent growth in computing resources and their widespread dissemination in daily life have brought about irreversible changes in educational measurement. Recent developments in computerized measurement are summarized by…

  17. Nursing Research Using Computerized Data Bases

    PubMed Central

    McCormick, Kathleen A.

    1981-01-01

    Because of the implementation of large computerized information systems, the analyses of patient care data important to clinical nursing research is possible. Simultaneously, the heralding of computer technology in clinical practice areas has necessitated new research ideas to be pursued. This paper will describe a taxonomy of research data available on hospital information systems that may be used for clinical nursing research.

  18. Computerized Numerical Control Test Item Bank.

    ERIC Educational Resources Information Center

    Reneau, Fred; And Others

    This guide contains 285 test items for use in teaching a course in computerized numerical control. All test items were reviewed, revised, and validated by incumbent workers and subject matter instructors. Items are provided for assessing student achievement in such aspects of programming and planning, setting up, and operating machines with…

  19. Research on ionospheric tomography based on variable pixel height

    NASA Astrophysics Data System (ADS)

    Zheng, Dunyong; Li, Peiqing; He, Jie; Hu, Wusheng; Li, Chaokui

    2016-05-01

    A novel ionospheric tomography technique based on variable pixel height was developed for the tomographic reconstruction of the ionospheric electron density distribution. The method considers the height of each pixel as an unknown variable, which is retrieved during the inversion process together with the electron density values. In contrast to conventional computerized ionospheric tomography (CIT), which parameterizes the model with a fixed pixel height, the variable-pixel-height computerized ionospheric tomography (VHCIT) model applies a disturbance to the height of each pixel. In comparison with conventional CIT models, the VHCIT technique achieved superior results in a numerical simulation. A careful validation of the reliability and superiority of VHCIT was performed. According to the results of the statistical analysis of the average root mean square errors, the proposed model offers an improvement by 15% compared with conventional CIT models.

  20. CT based computerized identification and analysis of human airways: A review

    SciTech Connect

    Pu Jiantao; Gu Suicheng; Liu Shusen; Zhu Shaocheng; Wilson, David; Siegfried, Jill M.; Gur, David

    2012-05-15

    As one of the most prevalent chronic disorders, airway disease is a major cause of morbidity and mortality worldwide. In order to understand its underlying mechanisms and to enable assessment of therapeutic efficacy of a variety of possible interventions, noninvasive investigation of the airways in a large number of subjects is of great research interest. Due to its high resolution in temporal and spatial domains, computed tomography (CT) has been widely used in clinical practices for studying the normal and abnormal manifestations of lung diseases, albeit there is a need to clearly demonstrate the benefits in light of the cost and radiation dose associated with CT examinations performed for the purpose of airway analysis. Whereas a single CT examination consists of a large number of images, manually identifying airway morphological characteristics and computing features to enable thorough investigations of airway and other lung diseases is very time-consuming and susceptible to errors. Hence, automated and semiautomated computerized analysis of human airways is becoming an important research area in medical imaging. A number of computerized techniques have been developed to date for the analysis of lung airways. In this review, we present a summary of the primary methods developed for computerized analysis of human airways, including airway segmentation, airway labeling, and airway morphometry, as well as a number of computer-aided clinical applications, such as virtual bronchoscopy. Both successes and underlying limitations of these approaches are discussed, while highlighting areas that may require additional work.

  1. CT based computerized identification and analysis of human airways: A review

    PubMed Central

    Pu, Jiantao; Gu, Suicheng; Liu, Shusen; Zhu, Shaocheng; Wilson, David; Siegfried, Jill M.; Gur, David

    2012-01-01

    As one of the most prevalent chronic disorders, airway disease is a major cause of morbidity and mortality worldwide. In order to understand its underlying mechanisms and to enable assessment of therapeutic efficacy of a variety of possible interventions, noninvasive investigation of the airways in a large number of subjects is of great research interest. Due to its high resolution in temporal and spatial domains, computed tomography (CT) has been widely used in clinical practices for studying the normal and abnormal manifestations of lung diseases, albeit there is a need to clearly demonstrate the benefits in light of the cost and radiation dose associated with CT examinations performed for the purpose of airway analysis. Whereas a single CT examination consists of a large number of images, manually identifying airway morphological characteristics and computing features to enable thorough investigations of airway and other lung diseases is very time-consuming and susceptible to errors. Hence, automated and semiautomated computerized analysis of human airways is becoming an important research area in medical imaging. A number of computerized techniques have been developed to date for the analysis of lung airways. In this review, we present a summary of the primary methods developed for computerized analysis of human airways, including airway segmentation, airway labeling, and airway morphometry, as well as a number of computer-aided clinical applications, such as virtual bronchoscopy. Both successes and underlying limitations of these approaches are discussed, while highlighting areas that may require additional work. PMID:22559631

  2. Computerized analysis of pelvic incidence from 3D images

    NASA Astrophysics Data System (ADS)

    Vrtovec, Tomaž; Janssen, Michiel M. A.; Pernuš, Franjo; Castelein, René M.; Viergever, Max A.

    2012-02-01

    The sagittal alignment of the pelvis can be evaluated by the angle of pelvic incidence (PI), which is constant for an arbitrary subject position and orientation and can be therefore compared among subjects in standing, sitting or supine position. In this study, PI was measured from three-dimensional (3D) computed tomography (CT) images of normal subjects that were acquired in supine position. A novel computerized method, based on image processing techniques, was developed to automatically determine the anatomical references required to measure PI, i.e. the centers of the femoral heads in 3D, and the center and inclination of the sacral endplate in 3D. Multiplanar image reformation was applied to obtain perfect sagittal views with all anatomical structures completely in line with the hip axis, from which PI was calculated. The resulting PI (mean+/-standard deviation) was equal to 46.6°+/-9.2° for male subjects (N = 189), 47.6°+/-10.7° for female subjects (N = 181), and 47.1°+/-10.0° for all subjects (N = 370). The obtained measurements of PI from 3D images were not biased by acquisition projection or structure orientation, because all anatomical structures were completely in line with the hip axis. The performed measurements in 3D therefore represent PI according to the actual geometrical relationships among anatomical structures of the sacrum, pelvis and hips, as observed from the perfect sagittal views.

  3. Computerized tomographic analysis of fluid flow in fractured tuff

    SciTech Connect

    Felice, C.W.; Sharer, J.C. ); Springer, E.P. )

    1992-01-01

    The purpose of this summary is to demonstrate the usefulness of X-ray computerized tomography to observe fluid flow down a fracture and rock matrix imbibition in a sample of Bandelier tuff. This was accomplished by using a tuff sample 152.4 mm long and 50.8 mm in diameter. A longitudinal fracture was created by cutting the core with a wire saw. The fractured piece was then coupled to its adjacent section to that the fracture was not expected. Water was injected into a dry sample at five flow rates and CT scanning performed at set intervals during the flow. Cross sectional images and longitudinal reconstructions were built and saturation profiles calculated for the sample at each time interval at each flow rate. The results showed that for the test conditions, the fracture was not a primary pathway of fluid flow down the sample. At a slow fluid injection rate into the dry sample, the fluid was imbibed into the rock uniformly down the length of the core. With increasing injection rates, the flow remained uniform over the core cross section through complete saturation.

  4. The NASA/LRC Computerized Test System

    NASA Technical Reports Server (NTRS)

    Richardson, W. Kirk; Washburn, David A.; Hopkins, William D.; Savage-Rumbaugh, E. Sue; Rumbaugh, Duane M.

    1990-01-01

    A new testing package, including apparatus and tasks for the behavioral study of a number of species in a variety of experiments is presented. The package is described with respect to the kinds of comparative psychological investigations for which it is best suited. The preliminary data generated within this new testing paradigm demonstrate that the NASA/LRC Computerized Test System provides a flexible yet powerful environment for the investigation of behavioral and psychological processes.

  5. Computerized flow monitors detect small kicks

    SciTech Connect

    McCann, D.; White, D. )

    1992-02-24

    This paper reports on a smart alarm system installed on a number of offshore rigs and one land rig which can detect kicks more quickly than conventional systems. This rapid kick detection improves rig safety because the smaller the detected influx, the easier it is to control the well. The extensive computerized monitoring system helps drilling personnel detect fluid influxes and fluid losses before the changes in flow would normally be apparent.

  6. Computerized implant-dentistry: Advances toward automation

    PubMed Central

    Gulati, Minkle; Anand, Vishal; Salaria, Sanjeev Kumar; Jain, Nikil; Gupta, Shilpi

    2015-01-01

    Advancements in the field of implantology such as three-dimensional imaging, implant-planning software, computer-aided-design/computer-aided-manufacturing (CAD/CAM) technology, computer-guided, and navigated implant surgery have led to the computerization of implant-dentistry. This three-dimensional computer-generated implant-planning and surgery has not only enabled accurate preoperative evaluation of the anatomic limitations but has also facilitated preoperative planning of implant positions along with virtual implant placement and subsequently transferring the virtual treatment plans onto the surgical phase via static (guided) or dynamic (navigated) systems aided by CAD/CAM technology. Computerized-implant-dentistry being highly predictable and minimally invasive in nature has also allowed implant placement in patients with medical comorbidities (e.g. radiation therapy, blood dyscrasias), in patients with complex problems following a significant alteration of the bony anatomy as a result of benign or malignant pathology of the jaws or trauma and in patients with other physical and emotional problems. With significant achievements accomplished in the field of computerized implant-dentistry, attempts are now been made toward complete automation of implant-dentistry. PMID:25810585

  7. Selection of Specific Protein Binders for Pre-Defined Targets from an Optimized Library of Artificial Helicoidal Repeat Proteins (alphaRep)

    PubMed Central

    Chevrel, Anne; Graille, Marc; Fourati-Kammoun, Zaineb; Desmadril, Michel; van Tilbeurgh, Herman; Minard, Philippe

    2013-01-01

    We previously designed a new family of artificial proteins named αRep based on a subgroup of thermostable helicoidal HEAT-like repeats. We have now assembled a large optimized αRep library. In this library, the side chains at each variable position are not fully randomized but instead encoded by a distribution of codons based on the natural frequency of side chains of the natural repeats family. The library construction is based on a polymerization of micro-genes and therefore results in a distribution of proteins with a variable number of repeats. We improved the library construction process using a “filtration” procedure to retain only fully coding modules that were recombined to recreate sequence diversity. The final library named Lib2.1 contains 1.7×109 independent clones. Here, we used phage display to select, from the previously described library or from the new library, new specific αRep proteins binding to four different non-related predefined protein targets. Specific binders were selected in each case. The results show that binders with various sizes are selected including relatively long sequences, with up to 7 repeats. ITC-measured affinities vary with Kd values ranging from micromolar to nanomolar ranges. The formation of complexes is associated with a significant thermal stabilization of the bound target protein. The crystal structures of two complexes between αRep and their cognate targets were solved and show that the new interfaces are established by the variable surfaces of the repeated modules, as well by the variable N-cap residues. These results suggest that αRep library is a new and versatile source of tight and specific binding proteins with favorable biophysical properties. PMID:24014183

  8. Computerized adaptive control weld skate with CCTV weld guidance project

    NASA Technical Reports Server (NTRS)

    Wall, W. A.

    1976-01-01

    This report summarizes progress of the automatic computerized weld skate development portion of the Computerized Weld Skate with Closed Circuit Television (CCTV) Arc Guidance Project. The main goal of the project is to develop an automatic welding skate demonstration model equipped with CCTV weld guidance. The three main goals of the overall project are to: (1) develop a demonstration model computerized weld skate system, (2) develop a demonstration model automatic CCTV guidance system, and (3) integrate the two systems into a demonstration model of computerized weld skate with CCTV weld guidance for welding contoured parts.

  9. Pseudolocal tomography

    DOEpatents

    Katsevich, A.J.; Ramm, A.G.

    1996-07-23

    Local tomographic data is used to determine the location and value of a discontinuity between a first internal density of an object and a second density of a region within the object. A beam of radiation is directed in a predetermined pattern through the region of the object containing the discontinuity. Relative attenuation data of the beam is determined within the predetermined pattern having a first data component that includes attenuation data through the region. The relative attenuation data is input to a pseudo-local tomography function, where the difference between the internal density and the pseudo-local tomography function is computed across the discontinuity. The pseudo-local tomography function outputs the location of the discontinuity and the difference in density between the first density and the second density. 7 figs.

  10. Pseudolocal tomography

    DOEpatents

    Katsevich, Alexander J.; Ramm, Alexander G.

    1996-01-01

    Local tomographic data is used to determine the location and value of a discontinuity between a first internal density of an object and a second density of a region within the object. A beam of radiation is directed in a predetermined pattern through the region of the object containing the discontinuity. Relative attenuation data of the beam is determined within the predetermined pattern having a first data component that includes attenuation data through the region. The relative attenuation data is input to a pseudo-local tomography function, where the difference between the internal density and the pseudo-local tomography function is computed across the discontinuity. The pseudo-local tomography function outputs the location of the discontinuity and the difference in density between the first density and the second density.