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Sample records for high-purity germanium gamma-camera

  1. Imaging capabilities of germanium gamma cameras

    Steidley, J.W.

    1977-01-01

    Quantitative methods of analysis based on the use of a computer simulation were developed and used to investigate the imaging capabilities of germanium gamma cameras. The main advantage of the computer simulation is that the inherent unknowns of clinical imaging procedures are removed from the investigation. The effects of patient scattered radiation were incorporated using a mathematical LSF model which was empirically developed and experimentally verified. Image modifying effects of patient motion, spatial distortions, and count rate capabilities were also included in the model. Spatial domain and frequency domain modeling techniques were developed and used in the simulation as required. The imaging capabilities of gamma cameras were assessed using low contrast lesion source distributions. The results showed that an improvement in energy resolution from 10% to 2% offers significant clinical advantages in terms of improved contrast, increased detectability, and reduced patient dose. The improvements are of greatest significance for small lesions at low contrast. The results of the computer simulation were also used to compare a design of a hypothetical germanium gamma camera with a state-of-the-art scintillation camera. The computer model performed a parametric analysis of the interrelated effects of inherent and technological limitations of gamma camera imaging. In particular, the trade-off between collimator resolution and collimator efficiency for detection of a given low contrast lesion was directly addressed. This trade-off is an inherent limitation of both gamma cameras. The image degrading effects of patient motion, camera spatial distortions, and low count rate were shown to modify the improvements due to better energy resolution. Thus, based on this research, the continued development of germanium cameras to the point of clinical demonstration is recommended

  2. Zone refining high-purity germanium

    Hubbard, G.S.; Haller, E.E.; Hansen, W.L.

    1977-10-01

    The effects of various parameters on germanium purification by zone refining have been examined. These parameters include the germanium container and container coatings, ambient gas and other operating conditions. Four methods of refining are presented which reproducibly yield 3.5 kg germanium ingots from which high purity (vertical barN/sub A/ - N/sub D/vertical bar less than or equal to2 x 10 10 cm -3 ) single crystals can be grown. A qualitative model involving binary and ternary complexes of Si, O, B, and Al is shown to account for the behavior of impurities at these low concentrations

  3. High-purity germanium crystal growing

    Hansen, W.L.; Haller, E.E.

    1982-10-01

    The germanium crystals used for the fabrication of nuclear radiation detectors are required to have a purity and crystalline perfection which is unsurpassed by any other solid material. These crystals should not have a net electrically active impurity concentration greater than 10 10 cm - 3 and be essentially free of charge trapping defects. Such perfect crystals of germanium can be grown only because of the highly favorable chemical and physical properties of this element. However, ten years of laboratory scale and commercial experience has still not made the production of such crystals routine. The origin and control of many impurities and electrically active defect complexes is now fairly well understood but regular production is often interrupted for long periods due to the difficulty of achieving the required high purity or to charge trapping in detectors made from crystals seemingly grown under the required conditions. The compromises involved in the selection of zone refining and crystal grower parts and ambients is discussed and the difficulty in controlling the purity of key elements in the process is emphasized. The consequences of growing in a hydrogen ambient are discussed in detail and it is shown how complexes of neutral defects produce electrically active centers

  4. Characterization of a high-purity germanium detector for small-animal SPECT.

    Johnson, Lindsay C; Campbell, Desmond L; Hull, Ethan L; Peterson, Todd E

    2011-09-21

    We present an initial evaluation of a mechanically cooled, high-purity germanium double-sided strip detector as a potential gamma camera for small-animal SPECT. It is 90 mm in diameter and 10 mm thick with two sets of 16 orthogonal strips that have a 4.5 mm width with a 5 mm pitch. We found an energy resolution of 0.96% at 140 keV, an intrinsic efficiency of 43.3% at 122 keV and a FWHM spatial resolution of approximately 1.5 mm. We demonstrated depth-of-interaction estimation capability through comparison of pinhole acquisitions with a point source on and off axes. Finally, a flood-corrected flood image exhibited a strip-level uniformity of less than 1%. This high-purity germanium offers many desirable properties for small-animal SPECT.

  5. Characterisation of two AGATA asymmetric high purity germanium capsules

    Colosimo, S.J.; Moon, S.; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Harkness-Brennan, L.; Judson, D.S.; Lazarus, I.H.; Nolan, P.J.; Simpson, J.; Unsworth, C.

    2015-01-01

    The AGATA spectrometer is an array of highly segmented high purity germanium detectors. The spectrometer uses pulse shape analysis in order to track Compton scattered γ-rays to increase the efficiency of nuclear spectroscopy studies. The characterisation of two high purity germanium detector capsules for AGATA of the same A-type has been performed at the University of Liverpool. This work will examine the uniformity of performance of the two capsules, including a comparison of the resolution and efficiency as well as a study of charge collection. The performance of the capsules shows good agreement, which is essential for the efficient operation of the γ-ray tracking array

  6. Characterisation of two AGATA asymmetric high purity germanium capsules

    Colosimo, S.J., E-mail: sjc@ns.ph.liv.ac.uk [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Moon, S.; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Harkness-Brennan, L.; Judson, D.S. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lazarus, I.H. [STFC Daresbury, Daresbury, Warrington WA4 4AD (United Kingdom); Nolan, P.J. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Simpson, J. [STFC Daresbury, Daresbury, Warrington WA4 4AD (United Kingdom); Unsworth, C. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

    2015-02-11

    The AGATA spectrometer is an array of highly segmented high purity germanium detectors. The spectrometer uses pulse shape analysis in order to track Compton scattered γ-rays to increase the efficiency of nuclear spectroscopy studies. The characterisation of two high purity germanium detector capsules for AGATA of the same A-type has been performed at the University of Liverpool. This work will examine the uniformity of performance of the two capsules, including a comparison of the resolution and efficiency as well as a study of charge collection. The performance of the capsules shows good agreement, which is essential for the efficient operation of the γ-ray tracking array.

  7. Carbon in high-purity germanium

    Haller, E.E.; Hansen, W.L.; Luke, P.; McMurray, R.; Jarrett, B.

    1981-10-01

    Using 14 C-spiked pyrolytic graphite-coated quartz crucibles for the growth of nine ultra-pure germanium single crystals, we have determined the carbon content and distribution in these crystals. Using autoradiography, we observe a rapidly decreasing carbon cluster concentration in successively grown crystals. Nuclear radiation detectors made from the crystals measure the betas from the internally decaying 14 C nuclei with close to 100% efficiency. An average value for the total carbon concentration [ 14 C + 12 C] is approx. 2 x 10 14 cm -3 , a value substantially larger than expected from earlier metallurgical studies. Contrary to the most recent measurement, we find the shape of the beta spectrum to agree very well with the statistical shape predicted for allowed transitions

  8. Event timing in high purity germanium coaxial detectors

    El-Ibiary, M.Y.

    1979-08-01

    The timing of gamma ray radiation in systems using high purity coaxial germanium detectors is analyzed and compared to that of systems using Ge(Li) detectors. The analysis takes into account the effect of the residual impurities on the electric field distribution, and hence on the rate of rise of the electrical pulses delivered to the timing module. Conditions under which the electric field distribution could lead to an improvement in timing performance, are identified. The results of the analysis confirm the experimental results published elsewhere and when compared with those for Ge(Li) detectors, which usually operate under conditions of charge carrier velocity saturation, confirm that high purity germanium detectors need not have inferior timing characteristics. A chart is given to provide a quantitative basis on which the trade off between the radius of the detector and its time resolution may be made

  9. Hydrogen concentration and distribution in high-purity germanium crystals

    Hansen, W.L.; Haller, E.E.; Luke, P.N.

    1981-10-01

    High-purity germanium crystals used for making nuclear radiation detectors are usually grown in a hydrogen ambient from a melt contained in a high-purity silica crucible. The benefits and problems encountered in using a hydrogen ambient are reviewed. A hydrogen concentration of about 2 x 10 15 cm -3 has been determined by growing crystals in hydrogen spiked with tritium and counting the tritium β-decays in detectors made from these crystals. Annealing studies show that the hydrogen is strongly bound, either to defects or as H 2 with a dissociation energy > 3 eV. This is lowered to 1.8 eV when copper is present. Etching defects in dislocation-free crystals grown in hydrogen have been found by etch stripping to have a density of about 1 x 10 7 cm -3 and are estimated to contain 10 8 H atoms each

  10. TIGRESS highly-segmented high-purity germanium clover detector

    Scraggs, H. C.; Pearson, C. J.; Hackman, G.; Smith, M. B.; Austin, R. A. E.; Ball, G. C.; Boston, A. J.; Bricault, P.; Chakrawarthy, R. S.; Churchman, R.; Cowan, N.; Cronkhite, G.; Cunningham, E. S.; Drake, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hyland, B.; Jones, B.; Leslie, J. R.; Martin, J.-P.; Morris, D.; Morton, A. C.; Phillips, A. A.; Sarazin, F.; Schumaker, M. A.; Svensson, C. E.; Valiente-Dobón, J. J.; Waddington, J. C.; Watters, L. M.; Zimmerman, L.

    2005-05-01

    The TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS) will consist of twelve units of four high-purity germanium (HPGe) crystals in a common cryostat. The outer contacts of each crystal will be divided into four quadrants and two lateral segments for a total of eight outer contacts. The performance of a prototype HPGe four-crystal unit has been investigated. Integrated noise spectra for all contacts were measured. Energy resolutions, relative efficiencies for both individual crystals and for the entire unit, and peak-to-total ratios were measured with point-like sources. Position-dependent performance was measured by moving a collimated source across the face of the detector.

  11. Automation of the Characterization of High Purity Germanium Detectors

    Dugger, Charles ``Chip''

    2014-09-01

    Neutrinoless double beta decay is a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. Currently there are several experiments trying to observe this process, including the Majorana DEMONSTRAOR experiment, which uses high purity germanium (HPGe) detectors to generate and search for these events. Because the event happens internally, it is essential to have the lowest background possible. This is done through passive detector shielding, as well as event discrimination techniques that distinguish between multi-site events characteristic of gamma-radiation, and single-site events characteristic of neutrinoless double beta decay. Before fielding such an experiment, the radiation response of the detectors must be characterized. A robotic arm is being tested for future calibration of HPGe detectors. The arm will hold a source at locations relative to the crystal while data is acquired. Several radioactive sources of varying energy levels will be used to determine the characteristics of the crystal. In this poster, I will present our work with the robot, as well as the characterization of data we took with an underground HPGe detector at the WIPP facility in Carlsbad, NM (2013). Neutrinoless double beta decay is a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. Currently there are several experiments trying to observe this process, including the Majorana DEMONSTRAOR experiment, which uses high purity germanium (HPGe) detectors to generate and search for these events. Because the event happens internally, it is essential to have the lowest background possible. This is done through passive detector shielding, as well as event discrimination techniques that distinguish between multi-site events characteristic of gamma-radiation, and single-site events characteristic of neutrinoless double beta decay. Before fielding such an experiment, the radiation response of

  12. Amorphous germanium as an electron or hole blocking contact on high-purity germanium detectors

    Hansen, W.L.; Haller, E.E.

    1976-10-01

    Experiments were performed in an attempt to make thin n + contacts on high-purity germanium by the solid phase/sup 1)/ epitaxial regrowth of arsenic doped amorphous germanium. After cleaning the crystal surface with argon sputtering and trying many combinations of layers, it was not found possible to induce recrystallization below 400 0 C. However, it was found that simple thermally evaporated amorphous Ge made fairly good electron or hole blocking contacts. Excellent spectrometers have been made with amorphous Ge replacing the n + contact. As presently produced, the amorphous Ge contact diodes show a large variation in high-voltage leakage current

  13. Trace radioactive measurement in foodstuffs using high purity germanium detector

    Morco, Ryan P.; Racho, Joseph Michael D.; Castaneda, Soledad S.; Almoneda, Rosalina V.; Pabroa, Preciosa Corazon B.; Sucgang, Raymond J.

    2010-01-01

    Trace radioactivity in food has been seriously considered sources of potential harm after the accidental radioactive releases in the last decades which led to contamination of the food chain. Countermeasures are being used to reduce the radiological health risk to the population and to ensure that public safety and international commitments are met. Investigation of radioactive traces in foods was carried out by gamma-ray spectrometry. The radionuclides being measured were fission products 1 37Cs and 1 34Cs and naturally occurring 4 0Κ. Gamma-ray measurements were performed using a hybrid gamma-ray counting system with coaxial p-type Tennelec High Purity Germanium (HPGe) detector with relative efficiency of 18.4%. Channels were calibrated to energies using a standard check source with 1 37Cs and 6 0Co present. Self-shielding within samples was taken into account by comparing directly with reference standards of similar matrix and geometry. Efficiencies of radionuclides of interests were accounted in calculating the activity concentrations in the samples. Efficiency calibration curve was generated using an in-house validated program called FINDPEAK, a least-square method that fits a polynomial up to sixth-order of equation. Lower Limits of Detection (LLD) obtained for both 1 37Cs and 1 34Cs ranges from 1-6 Bq/Kg depending on the sample matrix. In the last five years, there have been no foodstuffs analyzed exceeded the local and international regulatory limit of 1000Bq/Kg for the summed activities of 1 37Cs and 1 34Cs. (author)

  14. Melting point of high-purity germanium stable isotopes

    Gavva, V. A.; Bulanov, A. D.; Kut'in, A. M.; Plekhovich, A. D.; Churbanov, M. F.

    2018-05-01

    The melting point (Tm) of germanium stable isotopes 72Ge, 73Ge, 74Ge, 76Ge was determined by differential scanning calorimetry. With the increase in atomic mass of isotope the decrease in Tm is observed. The decrease was equal to 0.15 °C per the unit of atomic mass which qualitatively agrees with the value calculated by Lindemann formula accounting for the effect of "isotopic compression" of elementary cell.

  15. Fabrication and research of high purity germanium detectors with abrupt and thin diffusion layer

    Rodriguez Cabal, A. E.; Diaz Garcia, A.

    1997-01-01

    A different high purity germanium detector's fabrication method is described. A very thin diffusion film with an abrupt change of the type of conductivity is obtained. The fine diffusion layer thickness makes possibly their utilization in experimental systems in which all the data are elaborated directly on the computer. (author) [es

  16. Effect of the microstructure on electrical properties of high-purity germanium

    Podkopaev, O. I.; Shimanskii, A. F.; Molotkovskaya, N. O.; Kulakovskaya, T. V.

    2013-05-01

    The interrelation between the electrical properties and the microstructure of high-purity germanium crystals has been revealed. The electrical conductivity of polycrystalline samples increases and the life-time of nonequilibrium charge carriers in them decreases with a decrease in the crystallite sizes.

  17. Perfomance of a high purity germanium multi-detector telescope for long range particles

    Riepe, G.; Protic, D.; Suekoesd, C.; Didelez, J.P.; Frascaria, N.; Gerlic, E.; Hourani, E.; Morlet, M.

    1980-01-01

    A telescope of stacked high purity germanium detectors designed for long range charged particles was tested using medium energy protons. Particle identification and the rejection of the low energy tail could be accomplished on-line allowing the measurement of complex spectra. The efficiency of the detector stack for protons was measured up to 156 MeV incoming energy. The various factors affecting the energy resolution are discussed and their estimated contributions are compared with the experimental results

  18. Charge collection performance of a segmented planar high-purity germanium detector

    Cooper, R.J. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom)], E-mail: R.Cooper@liverpool.ac.uk; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD (United Kingdom); Dobson, J. [Rosemere Cancer Centre, Royal Preston Hospital, Preston PR2 9HT (United Kingdom)

    2008-10-01

    High-precision scans of a segmented planar high-purity germanium (HPGe) detector have been performed with a range of finely collimated gamma ray beams allowing the response as a function of gamma ray interaction position to be quantified. This has allowed the development of parametric pulse shape analysis (PSA) techniques and algorithms for the correction of imperfections in performance. In this paper we report on the performance of this detector, designed for use in a positron emission tomography (PET) development system.

  19. Control system for gamma camera

    Miller, D.W.

    1977-01-01

    An improved gamma camera arrangement is described which utilizing a solid state detector, formed of high purity germanium. the central arrangement of the camera operates to effect the carrying out of a trapezoidal filtering operation over antisymmetrically summed spatial signals through gated integration procedures utilizing idealized integrating intervals. By simultaneously carrying out peak energy evaluation of the input signals, a desirable control over pulse pile-up phenomena is achieved. Additionally, through the use of the time derivative of incoming pulse or signal energy information to initially enable the control system, a low level information evaluation is provided serving to enhance the signal processing efficiency of the camera

  20. Germanium field-effect transistor made from a high-purity substrate

    Hansen, W.L.; Goulding, F.S.; Haller, E.E.

    1978-11-01

    Field effect transistors have been fabricated on high-purity germanium substrates using low-temperature technology. The aim of this work is to preserve the low density of trapping centers in high-quality starting material by low-temperature ( 0 C) processing. The use of germanium promises to eliminate some of the traps which cause generation-recombination noise in silicon field-effect transistors (FET's) at low temperatures. Typically, the transconductance (g/sub m/) in the germanium FET's is 10 mA/V and the gate leakage can be less than 10 -12 A. Present devices exhibit a large 1/f noise component and most of this noise must be eliminated if they are to be competitive with silicon FET's commonly used in high-resolution nuclear spectrometers

  1. High-precision efficiency calibration of a high-purity co-axial germanium detector

    Blank, B., E-mail: blank@cenbg.in2p3.fr [Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, Université de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Souin, J.; Ascher, P.; Audirac, L.; Canchel, G.; Gerbaux, M.; Grévy, S.; Giovinazzo, J.; Guérin, H.; Nieto, T. Kurtukian; Matea, I. [Centre d' Etudes Nucléaires de Bordeaux Gradignan, UMR 5797, CNRS/IN2P3, Université de Bordeaux, Chemin du Solarium, BP 120, 33175 Gradignan Cedex (France); Bouzomita, H.; Delahaye, P.; Grinyer, G.F.; Thomas, J.C. [Grand Accélérateur National d' Ions Lourds, CEA/DSM, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, F-14076 CAEN Cedex 5 (France)

    2015-03-11

    A high-purity co-axial germanium detector has been calibrated in efficiency to a precision of about 0.15% over a wide energy range. High-precision scans of the detector crystal and γ-ray source measurements have been compared to Monte-Carlo simulations to adjust the dimensions of a detector model. For this purpose, standard calibration sources and short-lived online sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed β decays for tests of the weak-interaction standard model.

  2. Comparison of Response Characteristics of High-Purity Germanium Detectors using Analog Versus Digital Processing

    Luke, S J; Raschke, K

    2004-01-01

    In this article we will discuss some of the results of the response characteristics of High Purity germanium detectors using analog versus digital processing of the signals that are outputted from the detector. The discussion will focus on whether or not there is a significant difference in the response of the detector with digital electronics that it limits the ability of the detection system to get reasonable gamma ray spectrometric results. Particularly, whether or not the performance of the analysis code Pu600 is compromised

  3. Calibration of Single High Purity Germanium Detector for Whole Body Counter

    Taha, T.M.; Morsi, T.M.

    2009-01-01

    A new Accuscan II single germanium detector for whole body counter was installed in NRC (Egypt). The current paper concerned on calibration of single high purity germanium detector for whole body counter. Physical parameters affecting on performance of whole body counter such as linearity, minimum detectable activity and source detector distance, SDD were investigated. Counting efficiencies for the detector have been investigated in rear wall, fixed diagnostic position in air. Counting efficiencies for organ compartments such as thyroid, lung, upper and lower gastrointestinal tract have been investigated using transfer phantom in fixed diagnostic and screening positions respectively. The organ compartment efficiencies in screening geometry were higher than that value of diagnostic geometry by a factor of three. The committed dose equivalents of I-131 in thyroid were ranged from 0.073 ± 0.004 to 1.73±0.09 mSv and in lung was 0.02±0.001 mSv

  4. Bibliographical study on the high-purity germanium radiation detectors used in gamma and X spectrometry

    Bornand, Bernard; Friant, Alain

    1979-03-01

    The germanium or silicon lithium-drifted detectors, Ge(Li) or Si(Li), and high-purity germanium detectors, HP Ge (impurity concentration approximately 10 10 cm -3 ), are the most commonly used at the present time as gamma and X-ray spectrometers. The HP Ge detectors for which room temperature storage is the main characteristic can be obtained with a large volume and a thin window, and are used as the Ge(Li) in γ ray spectrometry or the Si(Li) in X-ray spectrometry. This publication reviews issues from 1974 to 1978 on the state of the art and applications of the HP Ge semiconductor detectors. 101 bibliographical notices with French summaries are presented. An index for authors, documents and periodicals, and subjects is included [fr

  5. Ultra low energy-ultra low background high purity germanium detectors for studies on dark matter

    Soma, A.K.; Singh, V.; Singh, L.; Singh, M.K.; Wong, H.T.

    2009-01-01

    Weakly Interacting Massive Particles (WIMP) are the leading DM candidates. Super symmetric particles (SUSY) are one of the leading WIMP candidates. To probe this least explored region Taiwan EXperiments On NeutrinO collaboration is pursuing research and development program by using High Purity Germanium detectors (HPGe). These detectors offer a matured technology to scale up the detectors and achieve sub-keV level threshold i.e. few hundreds of eV, economically. The various detectors developed by the collaboration is shown in the below figure. The current goal of the collaboration is to develop detectors of kg-scale target mass, ∼100 eV threshold and low-background specification for the studies on WIMPs, μ v and neutrino - nucleus coherent scattering

  6. High-purity germanium detection system for the in vivo measurement of americium and plutonium

    Tyree, W.H.; Falk, R.B.; Wood, C.B.; Liskey, R.W.

    1976-01-01

    A high-purity germanium (HPGe) array, photon-counting system has been developed for the Rocky Flats Plant Body-Counter Medical Facility. The newly improved system provides exceptional resolutions of low-energy X-ray and gamma-ray spectra associated with the in vivo deposition of plutonium and americium. Described are the operational parameters of the system and some qualitative results illustrating detector performance for the photon emissions produced from the decay of plutonium and americium between energy ranges from 10 to 100 kiloelectron volts. Since large amounts of data are easily generated with the system, data storage, analysis, and computer software developments continue to be an essential ingredient for processing spectral data obtained from the detectors. Absence of quantitative data is intentional. The primary concern of the study was to evaluate the effects of the various physical and electronic operational parameters before adding those related entirely to a human subject

  7. Methods to improve and understand the sensitivity of high purity germanium detectors for searches of rare events

    Volynets, Oleksandr

    2012-01-01

    Observation of neutrinoless double beta-decay could answer fundamental questions on the nature of neutrinos. High purity germanium detectors are well suited to search for this rare process in germanium. Successful operation of such experiments requires a good understanding of the detectors and the sources of background. Possible background sources not considered before in the presently running GERDA high purity germanium detector experiment were studied. Pulse shape analysis using artificial neural networks was used to distinguish between signal-like and background-like events. Pulse shape simulation was used to investigate systematic effects influencing the efficiency of the method. Possibilities to localize the origin of unwanted radiation using Compton back-tracking in a granular detector system were examined. Systematic effects in high purity germanium detectors influencing their performance have been further investigated using segmented detectors. The behavior of the detector response at different operational temperatures was studied. The anisotropy effects due to the crystallographic structure of germanium were facilitated in a novel way to determine the orientation of the crystallographic axes.

  8. Methods to improve and understand the sensitivity of high purity germanium detectors for searches of rare events

    Volynets, Oleksandr

    2012-07-27

    Observation of neutrinoless double beta-decay could answer fundamental questions on the nature of neutrinos. High purity germanium detectors are well suited to search for this rare process in germanium. Successful operation of such experiments requires a good understanding of the detectors and the sources of background. Possible background sources not considered before in the presently running GERDA high purity germanium detector experiment were studied. Pulse shape analysis using artificial neural networks was used to distinguish between signal-like and background-like events. Pulse shape simulation was used to investigate systematic effects influencing the efficiency of the method. Possibilities to localize the origin of unwanted radiation using Compton back-tracking in a granular detector system were examined. Systematic effects in high purity germanium detectors influencing their performance have been further investigated using segmented detectors. The behavior of the detector response at different operational temperatures was studied. The anisotropy effects due to the crystallographic structure of germanium were facilitated in a novel way to determine the orientation of the crystallographic axes.

  9. Improving axion detection sensitivity in high purity germanium detector based experiments

    Xu, Wenqin; Elliott, Steven

    2015-04-01

    Thanks to their excellent energy resolution and low energy threshold, high purity germanium (HPGe) crystals are widely used in low background experiments searching for neutrinoless double beta decay, e.g. the MAJORANA DEMONSTRATOR and the GERDA experiments, and low mass dark matter, e.g. the CDMS and the EDELWEISS experiments. A particularly interesting candidate for low mass dark matter is the axion, which arises from the Peccei-Quinn solution to the strong CP problem and has been searched for in many experiments. Due to axion-photon coupling, the postulated solar axions could coherently convert to photons via the Primakeoff effect in periodic crystal lattices, such as those found in HPGe crystals. The conversion rate depends on the angle between axions and crystal lattices, so the knowledge of HPGe crystal axis is important. In this talk, we will present our efforts to improve the HPGe experimental sensitivity to axions by considering the axis orientations in multiple HPGe crystals simultaneously. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.

  10. High Purity Germanium Detector as part of Health Canada's Mobile Nuclear Laboratory

    Stocki, Trevor J.; Bouchard, Claude; Rollings, John; Boudreau, Marc-Oliver; McCutcheon- Wickham, Rory; Bergman, Lauren [Radiation Protection Bureau, Health Canada, AL6302D, 775 Brookfield Road, Ottawa, K1A 0K9 (Canada)

    2014-07-01

    In the event of a nuclear emergency on Canadian soil, Health Canada has designed and equipped two Mobile Nuclear Labs (MNLs) which can be deployed near a radiological accident site to provide radiological measurement capabilities. These measurements would help public authorities to make informed decisions for radiation protection recommendations. One of the MNLs has been outfitted with a High Purity Germanium (HPGe) detector within a lead castle, which can be used for identification as well as quantification of gamma emitting radioisotopes in contaminated soil, water, and other samples. By spring 2014, Health Canada's second MNL will be equipped with a similar detector to increase sample analysis capacity and also provide redundancy if one of the detectors requires maintenance. The Mobile Nuclear Lab (MNL) with the HPGe detector has been successfully deployed in the field for various exercises. One of these field exercises was a dirty bomb scenario where an unknown radioisotope required identification. A second exercise was an inter-comparison between the measurements of spiked soil and water samples, by two field teams and a certified laboratory. A third exercise was the deployment of the MNL as part of a full scale nuclear exercise simulating an emergency at a Canadian nuclear power plant. The lessons learned from these experiences will be discussed. (authors)

  11. Electrical conductivity of high-purity germanium crystals at low temperature

    Yang, Gang; Kooi, Kyler; Wang, Guojian; Mei, Hao; Li, Yangyang; Mei, Dongming

    2018-05-01

    The temperature dependence of electrical conductivity of single-crystal and polycrystalline high-purity germanium (HPGe) samples has been investigated in the temperature range from 7 to 100 K. The conductivity versus inverse of temperature curves for three single-crystal samples consist of two distinct temperature ranges: a high-temperature range where the conductivity increases to a maximum with decreasing temperature, and a low-temperature range where the conductivity continues decreasing slowly with decreasing temperature. In contrast, the conductivity versus inverse of temperature curves for three polycrystalline samples, in addition to a high- and a low-temperature range where a similar conductive behavior is shown, have a medium-temperature range where the conductivity decreases dramatically with decreasing temperature. The turning point temperature ({Tm}) which corresponds to the maximum values of the conductivity on the conductivity versus inverse of temperature curves are higher for the polycrystalline samples than for the single-crystal samples. Additionally, the net carrier concentrations of all samples have been calculated based on measured conductivity in the whole measurement temperature range. The calculated results show that the ionized carrier concentration increases with increasing temperature due to thermal excitation, but it reaches saturation around 40 K for the single-crystal samples and 70 K for the polycrystalline samples. All these differences between the single-crystal samples and the polycrystalline samples could be attributed to trapping and scattering effects of the grain boundaries on the charge carriers. The relevant physical models have been proposed to explain these differences in the conductive behaviors between two kinds of samples.

  12. Measurement of energy transitions for the decay radiations of 75Ge and 69Ge in a high purity germanium detector

    Aydın, Güral; Usta, Metin; Oktay, Adem

    2018-06-01

    Photoactivation experiments have a wide range of application areas in nuclear, particle physics, and medical physics such as measuring energy levels and half-lifes of nuclei, experiments for understanding imaging methods in medicine, isotope production for patient treatment, radiation security and transportation, radiation therapy, and astrophysics processes. In this study, some energy transition values of the decay radiations of 75Ge and 69Ge, which are the products of photonuclear reactions (γ, n) with germanium isotopes (75Ge and 69Ge), were measured. The gamma spectrum as a result of atomic transitions were analysed by using a high purity semiconductor germanium detector and the energy transition values which are presented here were compared with the ones which are the best in literature. It was observed that the results presented are in agreement with literature in error range and some results have better precisions.

  13. Gamma camera system

    Miller, D.W.; Gerber, M.S.; Schlosser, P.A.; Steidley, J.W.

    1980-01-01

    A detailed description is given of a novel gamma camera which is designed to produce superior images than conventional cameras used in nuclear medicine. The detector consists of a solid state detector (e.g. germanium) which is formed to have a plurality of discrete components to enable 2-dimensional position identification. Details of the electronic processing circuits are given and the problems and limitations introduced by noise are discussed in full. (U.K.)

  14. Gamma camera

    Tschunt, E.; Platz, W.; Baer, Ul; Heinz, L.

    1978-01-01

    A gamma camera has a plurality of exchangeable collimators, one of which is replaceably mounted in the ray inlet opening of the camera, while the others are placed on separate supports. Supports are swingably mounted upon a column one above the other

  15. Gamma camera

    Schlosser, P.A.; Steidley, J.W.

    1980-01-01

    The design of a collimation system for a gamma camera for use in nuclear medicine is described. When used with a 2-dimensional position sensitive radiation detector, the novel system can produce superior images than conventional cameras. The optimal thickness and positions of the collimators are derived mathematically. (U.K.)

  16. High resolution gamma-ray spectroscopy at high count rates with a prototype High Purity Germanium detector

    Cooper, R. J.; Amman, M.; Vetter, K.

    2018-04-01

    High-resolution gamma-ray spectrometers are required for applications in nuclear safeguards, emergency response, and fundamental nuclear physics. To overcome one of the shortcomings of conventional High Purity Germanium (HPGe) detectors, we have developed a prototype device capable of achieving high event throughput and high energy resolution at very high count rates. This device, the design of which we have previously reported on, features a planar HPGe crystal with a reduced-capacitance strip electrode geometry. This design is intended to provide good energy resolution at the short shaping or digital filter times that are required for high rate operation and which are enabled by the fast charge collection afforded by the planar geometry crystal. In this work, we report on the initial performance of the system at count rates up to and including two million counts per second.

  17. Performance of A Compact Multi-crystal High-purity Germanium Detector Array for Measuring Coincident Gamma-ray Emissions

    Howard, Chris [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Daigle, Stephen [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Buckner, Matt [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Erikson, Luke E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Runkle, Robert C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stave, Sean C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Champagne, Art [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Cooper, Andrew [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Downen, Lori [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Glasgow, Brian D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kelly, Keegan [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Sallaska, Anne [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States)

    2015-02-18

    The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the 14N(p,γ)15O* reaction for several transition energies at an effective center of mass energy of 163 keV. Owing to the segmented nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within the uncertainties with the past measurements. Details of the analysis and detector performance will be presented.

  18. Performance of a compact multi-crystal high-purity germanium detector array for measuring coincident gamma-ray emissions

    Howard, Chris; Daigle, Stephen; Buckner, Matt [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Erikson, Luke E.; Runkle, Robert C. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Stave, Sean C., E-mail: Sean.Stave@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Champagne, Arthur E.; Cooper, Andrew; Downen, Lori [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Glasgow, Brian D. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kelly, Keegan; Sallaska, Anne [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States)

    2015-05-21

    The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the {sup 14}N(p,γ){sup 15}O{sup ⁎} reaction for several transition energies at an effective center-of-mass energy of 163 keV. Owing to the granular nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within their uncertainties with the past measurements. Details of the analysis and detector performance are presented.

  19. The Influence Of Dead Layer Effect On The Characteristics Of The High Purity Germanium P-Type Detector

    Ngo Quang Huy

    2011-01-01

    The present work aims at reviewing the studies of the influence of dead layer effect on the characteristics of a high purity germanium (HPGe) p-type detector, obtained by the author and his colleagues in the recent years. The object for study was the HPGe GC1518 detector-based gamma spectrometer of the Center for Nuclear Techniques, Ho Chi Minh City. The studying problems were: The modeling of an HPGe detector-based gamma spectrometer with using the MCNP code; the method of determining the thickness of dead layer by experimental measurements of gamma spectra and the calculations using MCNP code; the influence of material parameters and dead layer on detector efficiency; the increase of dead layer thickness over the operating time of the GC1518 detector; the influence of dead layer thickness increase on the decrease of detector efficiency; the dead layer effect for the gamma spectra measured in the GC1518 detector. (author)

  20. Surface passivation of high-purity germanium gamma-ray detector

    Alexiev, D.; Butcher, K.S.A.; Edmondson, M.; Lawson, E.M.

    1993-01-01

    The experimental work consists of two parts. The first involves fabrication of hyper-pure germanium gamma ray detectors using standard surface treatment, chemical etchings and containment in a suitable cryostat. Then, after cooling the detectors to 77 K, γ-ray emissions from radioisotopes are resolved, resolution, depletion depth, V R versus I R characteristics and /N A -N D / of the germanium are measured. The second part of the work involves investigation of surface states in an effort to achieve long-term stability of operating characteristics. Several methods are used: plasma hydrogenation, a-Si and a-Ge pinch-off effect and simple oxidation. A-Ge and a-Si thicknesses were measured using Rutherford backscattering techniques; surface states were measured with deep level transient spectroscopy and diode reverse current versus reverse voltage plots. Some scanning electron microscope measurements were used in determining major film contaminants during backscattering of a-Si and a-Ge films. Surface passivation studies revealed unexpected hole trapping defects generated when a-Ge:H film is applied. The a-Si:H films were found to be mechanically strong, no defect traps were found and preliminary results suggest that such films will be good passivants. 14 refs., 2 tabs., 7 figs., 13 ills

  1. Gamma camera

    Reiss, K.H.; Kotschak, O.; Conrad, B.

    1976-01-01

    A gamma camera with a simplified setup as compared with the state of engineering is described permitting, apart from good localization, also energy discrimination. Behind the usual vacuum image amplifier a multiwire proportional chamber filled with trifluorine bromium methane is connected in series. Localizing of the signals is achieved by a delay line, energy determination by means of a pulse height discriminator. With the aid of drawings and circuit diagrams, the setup and mode of operation are explained. (ORU) [de

  2. Gamma camera

    Berninger, W.H.

    1975-01-01

    The light pulse output of a scintillator, on which incident collimated gamma rays impinge, is detected by an array of photoelectric tubes each having a convexly curved photocathode disposed in close proximity to the scintillator. Electronic circuitry connected to outputs of the phototubes develops the scintillation event position coordinate electrical signals with good linearity and with substantial independence of the spacing between the scintillator and photocathodes so that the phototubes can be positioned as close to the scintillator as is possible to obtain less distortion in the field of view and improved spatial resolution as compared to conventional planar photocathode gamma cameras

  3. Cerebral distribution of 133Xe and blood flow measured with high purity germanium

    Reich, T.; Rusinek, H.; Youdin, M.; Clagnaz, M.

    1985-01-01

    Distribution of cerebral blood flow was measured with an array of 200 ultra-pure germanium radiation detectors and 133 Xe by inhalation. The array sees the head as a composite of different subvolumes and enables measurement of the concentration history of tracer every 1-10 sec in each subvolume simultaneously. Subvolume mean flows, (fm), and partition coefficients, lambda m, are derived by compartmental analysis of tissue concentration washout curves. Errors from cross talk, scalp radiation, look through, and assumed partition coefficients are eliminated. Average fm adjusted for 40 mm Hg PACO 2 in 14 cortical subvolumes (7 right, 7 left) of four normal 21-24 year old controls ranged from 50 to 60 ml/100 cc tissue/min, and lambda m ranged from 0.97 to 1.14. Average fm and lambda m in white matter was 24 ml/100 cc/min and 1.42 - 1.14 respectively. During CO 2 inhalation, right and left hemispheric fm increased 6.4% and 5.7%/mm Hg respectively, whereas white matter fm increased 2.2% and 3.4% mm Hg respectively. There was no systematic difference between front and back or dominant vs non-dominant sides. Three 73-84 year old controls had reduced fm and CO 2 reactivity in all subvolumes, lambda m was in the same range as in younger controls. Two patients with intracranial cerebrovascular disease showed excellent localization of ischemic subvolumes. One patient with asymptomatic unilateral 98% stenosis of the internal carotid artery had a similar distribution of blood flow in both hemispheres

  4. Gamma-ray observations of SN 1987A with an array of high-purity germanium detectors

    Sandie, W.G.; Nakano, G.H.; Chase, L.F. Jr.; Fishman, G.J.; Meegan, C.A.; Wilson, R.B.; Paciesas, W.

    1988-01-01

    A balloon borne gamma-ray spectrometer comprising an array of high-purity n-type germanium (HPGe) detectors having geometric area 119 cm 2 , resolution 2.5 keV at 1.0 MeV, surrounded by an active NaI (Tl) collimator and Compton suppressing anticoincidence shield nominally 10 cm thick, was flown from Alice Springs, Northern Territory, Australia, on May 29--30, 1987, 96 days after the observed neutrino pulse. The average column depth of residual atmosphere in the direction of SN 1987A at float altitude was 6.3 g cm-2 during the observation. SN 1987A was within the 22-deg full-width-half-maximum (FWHM) field of view for about 3300 s during May 29.9--30.3 UT. No excess gamma rays were observed at energies appropriate to the Ni(56)-Co(56) decay chain or from other lines in the energy region from 0.1 to 3.0 MeV. With 80% of the data analyzed, the 3-sigma upper limit obtained for the 1238-keV line from Co(56) at the instrument resolution (about 3 keV) is 1.3 x 10-3 photons cm-2 s-1

  5. Gamma camera

    Tschunt, E.; Platz, W.; Baer, U.; Heinz, L.

    1978-01-01

    A gamma camera has a plurality of exchangeable collimators, one of which is mounted in the ray inlet opening of the camera, while the others are placed on separate supports. The supports are swingably mounted upon a column one above the other through about 90 0 to a collimator exchange position. Each of the separate supports is swingable to a vertically aligned position, with limiting of the swinging movement and positioning of the support at the desired exchange position. The collimators are carried on the supports by means of a series of vertically disposed coil springs. Projections on the camera are movable from above into grooves of the collimator at the exchange position, whereupon the collimator is turned so that it is securely prevented from falling out of the camera head

  6. Gamma camera

    Conrad, B.; Heinzelmann, K.G.

    1975-01-01

    A gamma camera is described which obviates the distortion of locating signals generally caused by the varied light conductive capacities of the light conductors in that the flow of light through each light conductor may be varied by means of a shutter. A balancing of the flow of light through each of the individual light conductors, in effect, collective light conductors may be balanced on the basis of their light conductive capacities or properties, so as to preclude a distortion of the locating signals caused by the varied light conductive properties of the light conductors. Each light conductor has associated therewith two, relative to each other, independently adjustable shutters, of which one forms a closure member and the other an adjusting shutter. In this embodiment of the invention it is thus possible to block all of the light conductors leading to a photoelectric transducer, with the exception of those light conductors which are to be balanced. The balancing of the individual light conductors may then be obtained on the basis of the output signals of the photoelectric transducer. (auth)

  7. Sensitive method for the determination of rare earth elements by radioisotope-excited XRF employing a high purity germanium detector in optimized geometry

    Lal, M.; Joseph, D.; Patra, P.K.; Bajpal, H.N.

    1993-01-01

    A close-coupled side-source geometrical configuration is proposed for obtaining a high detection sensitivity for rare earth elements (57 ≤ Z ≤ 69) by radioisotope-excited energy-dispersive x-ray fluorescence spectrometry. In this configuration a disc source of 241 Am (100 mCi), a high-purity germanium detector and thin samples of rare earth elements on a Mylar backing are employed in an optimized geometry to achieve detection limits in the range 20-50 ng for these elements in a counting time of 1 h. (author)

  8. Monte Carlo simulation of gamma-ray interactions in an over-square high-purity germanium detector for in-vivo measurements

    Saizu, Mirela Angela

    2016-09-01

    The developments of high-purity germanium detectors match very well the requirements of the in-vivo human body measurements regarding the gamma energy ranges of the radionuclides intended to be measured, the shape of the extended radioactive sources, and the measurement geometries. The Whole Body Counter (WBC) from IFIN-HH is based on an “over-square” high-purity germanium detector (HPGe) to perform accurate measurements of the incorporated radionuclides emitting X and gamma rays in the energy range of 10 keV-1500 keV, under conditions of good shielding, suitable collimation, and calibration. As an alternative to the experimental efficiency calibration method consisting of using reference calibration sources with gamma energy lines that cover all the considered energy range, it is proposed to use the Monte Carlo method for the efficiency calibration of the WBC using the radiation transport code MCNP5. The HPGe detector was modelled and the gamma energy lines of 241Am, 57Co, 133Ba, 137Cs, 60Co, and 152Eu were simulated in order to obtain the virtual efficiency calibration curve of the WBC. The Monte Carlo method was validated by comparing the simulated results with the experimental measurements using point-like sources. For their optimum matching, the impact of the variation of the front dead layer thickness and of the detector photon absorbing layers materials on the HPGe detector efficiency was studied, and the detector’s model was refined. In order to perform the WBC efficiency calibration for realistic people monitoring, more numerical calculations were generated simulating extended sources of specific shape according to the standard man characteristics.

  9. Performance and stability tests of bare high purity germanium detectors in liquid argon for the GERDA experiment

    Barnabe Heider, Marik

    2009-05-27

    GERDA will search for neutrinoless double beta decay of {sup 76}Ge by using a novel approach of bare germanium detectors in liquid argon (LAr). Enriched germanium detectors from the previous Heidelberg-Moscow and IGEX experiments have been reprocessed and will be deployed in GERDA Phase-I. At the center of this thesis project is the study of the performance of bare germanium detectors in cryogenic liquids. Identical detector performance as in vacuum cryostats (2.2 keV FWHM at 1.3 MeV) was achieved in cryogenic liquids with a new low-mass detector assembly and contacts. One major result is the discovery of a radiation induced leakage current (LC) increase when operating bare detectors with standard passivation layers in LAr. Charge collection and build-up on the passivation layer were identified as the origin of the LC increase. It was found that diodes without passivation do not exhibit this feature. Three month-long stable operation in LAr at {proportional_to} 5 pA LC under periodic gamma irradiation demonstrated the suitability of the modi ed detector design. Based on these results, all Phase-I detectors were reprocessed without passivation layer and subsequently successfully characterized in LAr in the GERDA underground Detector Laboratory. The mass loss during the reprocessing was {proportional_to}300 g out of 17.9 kg and the exposure above ground {proportional_to} 5 days. This results in a negligible cosmogenic background increase of {proportional_to} 5.10{sup -4} cts/(keV.kg.y) at {sup 76}Ge Q{sub {beta}}{sub {beta}} for {sup 60}Co and {sup 68}Ge. (orig.)

  10. An imaging system for a gamma camera

    Miller, D.W.; Gerber, M.S.

    1980-01-01

    A detailed description is given of a novel gamma camera which is designed to produce superior images than conventional cameras used in nuclear medicine. The detector consists of a solid state detector (e.g. germanium) which is formed to have a plurality of discrete components to enable 2-dimensional position identification. Details of the electronic processing circuits are given and the problems and limitations introduced by noise are discussed in full. (U.K.)

  11. Scanning gamma camera

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

    1977-01-01

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

  12. Gamma camera display system

    Stout, K.J.

    1976-01-01

    A gamma camera having an array of photomultipliers coupled via pulse shaping circuitry and a resistor weighting circuit to a display for forming an image of a radioactive subject is described. A linearizing circuit is coupled to the weighting circuit, the linearizing circuit including a nonlinear feedback circuit with diode coupling to the weighting circuit for linearizing the correspondence between points of the display and points of the subject. 4 Claims, 5 Drawing Figures

  13. Gamma camera system

    Miller, D.W.; Gerber, M.S.

    1977-01-01

    A gamma camera system having control components operating in conjunction with a solid state detector is described. The detector is formed of a plurality of discrete components which are associated in geometrical or coordinate arrangement defining a detector matrix to derive coordinate signal outputs. These outputs are selectively filtered and summed to form coordinate channel signals and corresponding energy channel signals. A control feature of the invention regulates the noted summing and filtering performance to derive data acceptance signals which are addressed to further treating components. The latter components include coordinate and enery channel multiplexers as well as energy-responsive selective networks. A sequential control is provided for regulating the signal processing functions of the system to derive an overall imaging cycle

  14. Analyzer for gamma cameras diagnostic

    Oramas Polo, I.; Osorio Deliz, J. F.; Diaz Garcia, A.

    2013-01-01

    This research work was carried out to develop an analyzer for gamma cameras diagnostic. It is composed of an electronic system that includes hardware and software capabilities, and operates from the acquisition of the 4 head position signals of a gamma camera detector. The result is the spectrum of the energy delivered by nuclear radiation coming from the camera detector head. This system includes analog processing of position signals from the camera, digitization and the subsequent processing of the energy signal in a multichannel analyzer, sending data to a computer via a standard USB port and processing of data in a personal computer to obtain the final histogram. The circuits are composed of an analog processing board and a universal kit with micro controller and programmable gate array. (Author)

  15. Decision about buying a gamma camera

    Ganatra, R D

    1993-12-31

    A large part of the referral to a nuclear medicine department is usually for imaging studies. Sooner or later, the nuclear medicine specialist will be called upon to make a decision about when and what type of gamma camera to buy. There is no longer an option of choosing between a rectilinear scanner and a gamma camera as the former is virtually out of the market. The decision that one has to make is when to invest in a gamma camera, and then on what basis to select the gamma camera 1 tab., 1 fig

  16. Decision about buying a gamma camera

    Ganatra, R.D.

    1992-01-01

    A large part of the referral to a nuclear medicine department is usually for imaging studies. Sooner or later, the nuclear medicine specialist will be called upon to make a decision about when and what type of gamma camera to buy. There is no longer an option of choosing between a rectilinear scanner and a gamma camera as the former is virtually out of the market. The decision that one has to make is when to invest in a gamma camera, and then on what basis to select the gamma camera

  17. Gate Simulation of a Gamma Camera

    Abidi, Sana; Mlaouhi, Zohra

    2008-01-01

    Medical imaging is a very important diagnostic because it allows for an exploration of the internal human body. The nuclear imaging is an imaging technique used in the nuclear medicine. It is to determine the distribution in the body of a radiotracers by detecting the radiation it emits using a detection device. Two methods are commonly used: Single Photon Emission Computed Tomography (SPECT) and the Positrons Emission Tomography (PET). In this work we are interested on modelling of a gamma camera. This simulation is based on Monte-Carlo language and in particular Gate simulator (Geant4 Application Tomographic Emission). We have simulated a clinical gamma camera called GAEDE (GKS-1) and then we validate these simulations by experiments. The purpose of this work is to monitor the performance of these gamma camera and the optimization of the detector performance and the the improvement of the images quality. (Author)

  18. Performance assessment of gamma cameras. Part 1

    Elliot, A.T.; Short, M.D.; Potter, D.C.; Barnes, K.J.

    1980-11-01

    The Dept. of Health and Social Security and the Scottish Home and Health Dept. has sponsored a programme of measurements of the important performance characteristics of 15 leading types of gamma cameras providing a routine radionuclide imaging service in hospitals throughout the UK. Measurements have been made of intrinsic resolution, system resolution, non-uniformity, spatial distortion, count rate performance, sensitivity, energy resolution and shield leakage. The main aim of this performance assessment was to provide sound information to the NHS to ease the task of those responsible for the purchase of gamma cameras. (U.K.)

  19. Advanced system for Gamma Cameras modernization

    Osorio Deliz, J. F.; Diaz Garcia, A.; Arista Romeu, E. J.

    2015-01-01

    Analog and digital gamma cameras still largely used in developing countries. Many of them rely in old hardware electronics, which in many cases limits their use in actual nuclear medicine diagnostic studies. Consequently, there are different worldwide companies that produce medical equipment engaged into a partial or total Gamma Cameras modernization. Present work has demonstrated the possibility of substitution of almost entire signal processing electronics placed at inside a Gamma Camera detector head by a digitizer PCI card. this card includes four 12 Bits Analog-to-Digital-Converters of 50 MHz speed. It has been installed in a PC and controlled through software developed in Lab View. Besides, there were done some changes to the hardware inside the detector head including redesign of the Orientation Display Block (ODA card). Also a new electronic design was added to the Microprocessor Control Block (MPA card) which comprised a PIC micro controller acting as a tuning system for individual Photomultiplier Tubes. The images, obtained by measurement of 99m Tc point radioactive source, using modernized camera head demonstrate its overall performance. The system was developed and tested in an old Gamma Camera ORBITER II SIEMENS GAMMASONIC at National Institute of Oncology and Radiobiology (INOR) under CAMELUD project supported by National Program PNOULU and IAEA . (Author)

  20. Toward standardising gamma camera quality control procedures

    Alkhorayef, M.A.; Alnaaimi, M.A.; Alduaij, M.A.; Mohamed, M.O.; Ibahim, S.Y.; Alkandari, F.A.; Bradley, D.A.

    2015-01-01

    Attaining high standards of efficiency and reliability in the practice of nuclear medicine requires appropriate quality control (QC) programs. For instance, the regular evaluation and comparison of extrinsic and intrinsic flood-field uniformity enables the quick correction of many gamma camera problems. Whereas QC tests for uniformity are usually performed by exposing the gamma camera crystal to a uniform flux of gamma radiation from a source of known activity, such protocols can vary significantly. Thus, there is a need for optimization and standardization, in part to allow direct comparison between gamma cameras from different vendors. In the present study, intrinsic uniformity was examined as a function of source distance, source activity, source volume and number of counts. The extrinsic uniformity and spatial resolution were also examined. Proper standard QC procedures need to be implemented because of the continual development of nuclear medicine imaging technology and the rapid expansion and increasing complexity of hybrid imaging system data. The present work seeks to promote a set of standard testing procedures to contribute to the delivery of safe and effective nuclear medicine services. - Highlights: • Optimal parameters for quality control of the gamma camera are proposed. • For extrinsic and intrinsic uniformity a minimum of 15,000 counts is recommended. • For intrinsic flood uniformity the activity should not exceed 100 µCi (3.7 MBq). • For intrinsic uniformity the source to detector distance should be at least 60 cm. • The bar phantom measurement must be performed with at least 15 million counts.

  1. [Analog gamma camera digitalization computer system].

    Rojas, G M; Quintana, J C; Jer, J; Astudillo, S; Arenas, L; Araya, H

    2004-01-01

    Digitalization of analogue gamma cameras systems, using special acquisition boards in microcomputers and appropriate software for acquisition and processing of nuclear medicine images is described in detail. Microcomputer integrated systems interconnected by means of a Local Area Network (LAN) and connected to several gamma cameras have been implemented using specialized acquisition boards. The PIP software (Portable Image Processing) was installed on each microcomputer to acquire and preprocess the nuclear medicine images. A specialized image processing software has been designed and developed for these purposes. This software allows processing of each nuclear medicine exam, in a semiautomatic procedure, and recording of the results on radiological films. . A stable, flexible and inexpensive system which makes it possible to digitize, visualize, process, and print nuclear medicine images obtained from analogue gamma cameras was implemented in the Nuclear Medicine Division. Such a system yields higher quality images than those obtained with analogue cameras while keeping operating costs considerably lower (filming: 24.6%, fixing 48.2% and developing 26%.) Analogue gamma camera systems can be digitalized economically. This system makes it possible to obtain optimal clinical quality nuclear medicine images, to increase the acquisition and processing efficiency, and to reduce the steps involved in each exam.

  2. Gamma cameras - a method of evaluation

    Oates, L.; Bibbo, G.

    2000-01-01

    Full text: With the sophistication and longevity of the modern gamma camera it is not often that the need arises to evaluate a gamma camera for purchase. We have recently been placed in the position of retiring our two single headed cameras of some vintage and replacing them with a state of the art dual head variable angle gamma camera. The process used for the evaluation consisted of five parts: (1) Evaluation of the technical specification as expressed in the tender document; (2) A questionnaire adapted from the British Society of Nuclear Medicine; (3) Site visits to assess gantry configuration, movement, patient access and occupational health, welfare and safety considerations; (4) Evaluation of the processing systems offered; (5) Whole of life costing based on equally configured systems. The results of each part of the evaluation were expressed using a weighted matrix analysis with each of the criteria assessed being weighted in accordance with their importance to the provision of an effective nuclear medicine service for our centre and the particular importance to paediatric nuclear medicine. This analysis provided an objective assessment of each gamma camera system from which a purchase recommendation was made. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  3. New nuclear medicine gamma camera systems

    Villacorta, Edmundo V.

    1997-01-01

    The acquisition of the Open E.CAM and DIACAM gamma cameras by Makati Medical Center is expected to enhance the capabilities of its nuclear medicine facilities. When used as an aid to diagnosis, nuclear medicine entails the introduction of a minute amount of radioactive material into the patient; thus, no reaction or side-effect is expected. When it reaches the particular target organ, depending on the radiopharmaceutical, a lesion will appear as a decrease (cold) area or increase (hot) area in the radioactive distribution as recorded byu the gamma cameras. Gamma camera images in slices or SPECT (Single Photon Emission Computer Tomography), increase the sensitivity and accuracy in detecting smaller and deeply seated lesions, which otherwise may not be detected in the regular single planar images. Due to the 'open' design of the equipment, claustrophobic patients will no longer feel enclosed during the procedure. These new gamma cameras yield improved resolution and superb image quality, and the higher photon sensitivity shortens imaging acquisition time. The E.CAM, which is the latest generation gamma camera, is featured by its variable angle dual-head system, the only one available in the Philipines, and the excellent choice for Myocardial Perfusion Imaging (MPI). From the usual 45 minutes, the acquisition time for gated SPECT imaging of the heart has now been remarkably reduced to 12 minutes. 'Gated' infers snap-shots of the heart in selected phases of its contraction and relaxation as triggered by ECG. The DIACAM is installed in a room with access outside the main entrance of the department, intended specially for bed-borne patients. Both systems are equipped with a network of high performance Macintosh ICOND acquisition and processing computers. Added to the hardware is the ICON processing software which allows total simultaneous acquisition and processing capabilities in the same operator's terminal. Video film and color printers are also provided. Together

  4. A novel fully integrated handheld gamma camera

    Massari, R.; Ucci, A.; Campisi, C.; Scopinaro, F.; Soluri, A.

    2016-01-01

    In this paper, we present an innovative, fully integrated handheld gamma camera, namely designed to gather in the same device the gamma ray detector with the display and the embedded computing system. The low power consumption allows the prototype to be battery operated. To be useful in radioguided surgery, an intraoperative gamma camera must be very easy to handle since it must be moved to find a suitable view. Consequently, we have developed the first prototype of a fully integrated, compact and lightweight gamma camera for radiopharmaceuticals fast imaging. The device can operate without cables across the sterile field, so it may be easily used in the operating theater for radioguided surgery. The prototype proposed consists of a Silicon Photomultiplier (SiPM) array coupled with a proprietary scintillation structure based on CsI(Tl) crystals. To read the SiPM output signals, we have developed a very low power readout electronics and a dedicated analog to digital conversion system. One of the most critical aspects we faced designing the prototype was the low power consumption, which is mandatory to develop a battery operated device. We have applied this detection device in the lymphoscintigraphy technique (sentinel lymph node mapping) comparing the results obtained with those of a commercial gamma camera (Philips SKYLight). The results obtained confirm a rapid response of the device and an adequate spatial resolution for the use in the scintigraphic imaging. This work confirms the feasibility of a small gamma camera with an integrated display. This device is designed for radioguided surgery and small organ imaging, but it could be easily combined into surgical navigation systems.

  5. A novel fully integrated handheld gamma camera

    Massari, R.; Ucci, A.; Campisi, C. [Biostructure and Bioimaging Institute (IBB), National Research Council of Italy (CNR), Rome (Italy); Scopinaro, F. [University of Rome “La Sapienza”, S. Andrea Hospital, Rome (Italy); Soluri, A., E-mail: alessandro.soluri@ibb.cnr.it [Biostructure and Bioimaging Institute (IBB), National Research Council of Italy (CNR), Rome (Italy)

    2016-10-01

    In this paper, we present an innovative, fully integrated handheld gamma camera, namely designed to gather in the same device the gamma ray detector with the display and the embedded computing system. The low power consumption allows the prototype to be battery operated. To be useful in radioguided surgery, an intraoperative gamma camera must be very easy to handle since it must be moved to find a suitable view. Consequently, we have developed the first prototype of a fully integrated, compact and lightweight gamma camera for radiopharmaceuticals fast imaging. The device can operate without cables across the sterile field, so it may be easily used in the operating theater for radioguided surgery. The prototype proposed consists of a Silicon Photomultiplier (SiPM) array coupled with a proprietary scintillation structure based on CsI(Tl) crystals. To read the SiPM output signals, we have developed a very low power readout electronics and a dedicated analog to digital conversion system. One of the most critical aspects we faced designing the prototype was the low power consumption, which is mandatory to develop a battery operated device. We have applied this detection device in the lymphoscintigraphy technique (sentinel lymph node mapping) comparing the results obtained with those of a commercial gamma camera (Philips SKYLight). The results obtained confirm a rapid response of the device and an adequate spatial resolution for the use in the scintigraphic imaging. This work confirms the feasibility of a small gamma camera with an integrated display. This device is designed for radioguided surgery and small organ imaging, but it could be easily combined into surgical navigation systems.

  6. Measurements of gamma (γ)-emitting radionuclides with a high-purity germanium detector: the methods and reliability of our environmental assessments on the Fukushima 1 Nuclear Power Plant accident.

    Mimura, Tetsuro; Mimura, Mari; Komiyama, Chiyo; Miyamoto, Masaaki; Kitamura, Akira

    2014-01-01

    The severe accident of Fukushima 1 Nuclear Power Plant due to the Tohoku Region Pacific Coast Earthquake in 11 March 2011 caused wide contamination and pollution by radionuclides in Fukushima and surrounding prefectures. In the current JPR symposium, a group of plant scientists attempted to examine the impact of the radioactive contamination on wild and cultivated plants. Measurements of gamma (γ) radiation from radionuclides in "Fukushima samples", which we called and collected from natural and agricultural areas in Fukushima prefecture were mostly done with a high-purity Ge detector in the Graduate School of Maritime Sciences, Kobe University. In this technical note, we describe the methods of sample preparation and measurements of radioactivity of the samples and discuss the reliability of our data in regards to the International Atomic Energy Agency (IAEA) Interlaboratory comparisons and proficiency test (IAEA proficiency test).

  7. Production of high purity radiothallium

    Lebowitz, E.; Greene, M.W.

    1976-01-01

    The method of producing high-purity thallium-201 for use as a myocardial scanning agent comprises the steps of irradiating a thallium target with protons to give the reaction 203 Tl(p,3n) 201 Pb, separating in ion exchange columns the lead from the thallium isotopes, permitting the lead to decay, and then purifying the thallium solution and converting the thallium present to thallous form in which it can be used

  8. Dynamic gamma camera scintigraphy in primary hypoovarism

    Peshev, N.; Mladenov, B.; Topalov, I.; Tsanev, Ts.

    1988-01-01

    Twenty-seven patients with primary hypoovarism and 10 controls were examined. After intravenous injection of 111 to 175 MBq 99m Tc pertechnetate, dynamic gamma camera scintigraphy for 15 minutes was carried out. In the patients with primary amenorrhea no functioning ovarial tissue was visualized or the ovaries were diminished in size, strongly reduced and non-homogenous accumulation of the radionuclide with unclear and uneven delineation were observed. In the patients with primary infertility, the gamma camera investigation gave information not only about the presence of ovarial parenchyma, but about the extent of the inflammatory process, too. In the patients after surgical intervention, the dynamic radioisotope investigation gave information about the volume and the site of the surgical intervention, as well as about the conditions of the residual parenchyma

  9. Gamma camera performance: technical assessment protocol

    Bolster, A.A.; Waddington, W.A.

    1996-01-01

    This protocol addresses the performance assessment of single and dual headed gamma cameras. No attempt is made to assess the performance of any associated computing systems. Evaluations are usually performed on a gamma camera commercially available within the United Kingdom and recently installed at a clinical site. In consultation with the manufacturer, GCAT selects the site and liaises with local staff to arrange a mutually convenient time for assessment. The manufacturer is encouraged to have a representative present during the evaluation. Three to four days are typically required for the evaluation team to perform the necessary measurements. When access time is limited, the team will modify the protocol to test the camera as thoroughly as possible. Data are acquired on the camera's computer system and are subsequently transferred to the independent GCAT computer system for analysis. This transfer from site computer to the independent system is effected via a hardware interface and Interfile data transfer. (author)

  10. Gamma camera performance: technical assessment protocol

    Bolster, A.A. [West Glasgow Hospitals NHS Trust, London (United Kingdom). Dept. of Clinical Physics; Waddington, W.A. [University College London Hospitals NHS Trust, London (United Kingdom). Inst. of Nuclear Medicine

    1996-12-31

    This protocol addresses the performance assessment of single and dual headed gamma cameras. No attempt is made to assess the performance of any associated computing systems. Evaluations are usually performed on a gamma camera commercially available within the United Kingdom and recently installed at a clinical site. In consultation with the manufacturer, GCAT selects the site and liaises with local staff to arrange a mutually convenient time for assessment. The manufacturer is encouraged to have a representative present during the evaluation. Three to four days are typically required for the evaluation team to perform the necessary measurements. When access time is limited, the team will modify the protocol to test the camera as thoroughly as possible. Data are acquired on the camera`s computer system and are subsequently transferred to the independent GCAT computer system for analysis. This transfer from site computer to the independent system is effected via a hardware interface and Interfile data transfer. (author).

  11. Gamma camera scatter suppression unit WAM

    Kishi, Haruo; Shibahara, Noriyuki; Hirose, Yoshiharu; Shimonishi, Yoshihiro; Oumura, Masahiro; Ikeda, Hozumi; Hamada, Kunio; Ochi, Hironobu; Itagane, Hiroshi.

    1990-01-01

    In gamma camera imaging, scattered radiation is one of big factors to decrease image contrast. Simply, scatter suppression makes signal to noise ratio larger, but it makes statistics error because of radionuclide injection limit to the human body. EWA is a new method that suppresses scattered radiation and improves image contrast. In this article, WAM which is commercialized EWA method by Siemens Gammasonics Inc. is presented. (author)

  12. Quality assessment of gamma camera systems

    Kindler, M.

    1985-01-01

    There are methods and equipment in nuclear medical diagnostics that allow selective visualisation of the functioning of organs or organ systems, using radioactive substances for labelling and demonstration of metabolic processes. Following a previous contribution on fundamentals and systems components of a gamma camera system, the article in hand deals with the quality characteristics of such a system and with practical quality control and its significance for clinical applications. [de

  13. The making of analog module for gamma camera interface

    Yulinarsari, Leli; Rl, Tjutju; Susila, Atang; Sukandar

    2003-01-01

    The making of an analog module for gamma camera has been conducted. For computerization of planar gamma camera 37 PMT it has been developed interface hardware technology and software between the planar gamma camera with PC. With this interface gamma camera image information (Originally analog signal) was changed to digital single, therefore processes of data acquisition, image quality increase and data analysis as well as data base processing can be conducted with the help of computers, there are three gamma camera main signals, i.e. X, Y and Z . This analog module makes digitation of analog signal X and Y from the gamma camera that conveys position information coming from the gamma camera crystal. Analog conversion to digital was conducted by 2 converters ADC 12 bit with conversion time 800 ns each, conversion procedure for each coordinate X and Y was synchronized using suitable strobe signal Z for information acceptance

  14. Modeling and simulation of gamma camera

    Singh, B.; Kataria, S.K.; Samuel, A.M.

    2002-08-01

    Simulation techniques play a vital role in designing of sophisticated instruments and also for the training of operating and maintenance staff. Gamma camera systems have been used for functional imaging in nuclear medicine. Functional images are derived from the external counting of the gamma emitting radioactive tracer that after introduction in to the body mimics the behavior of native biochemical compound. The position sensitive detector yield the coordinates of the gamma ray interaction with the detector and are used to estimate the point of gamma ray emission within the tracer distribution space. This advanced imaging device is thus dependent on the performance of algorithm for coordinate computing, estimation of point of emission, generation of image and display of the image data. Contemporary systems also have protocols for quality control and clinical evaluation of imaging studies. Simulation of this processing leads to understanding of the basic camera design problems. This report describes a PC based package for design and simulation of gamma camera along with the options of simulating data acquisition and quality control of imaging studies. Image display and data processing the other options implemented in SIMCAM will be described in separate reports (under preparation). Gamma camera modeling and simulation in SIMCAM has preset configuration of the design parameters for various sizes of crystal detector with the option to pack the PMT on hexagon or square lattice. Different algorithm for computation of coordinates and spatial distortion removal are allowed in addition to the simulation of energy correction circuit. The user can simulate different static, dynamic, MUGA and SPECT studies. The acquired/ simulated data is processed for quality control and clinical evaluation of the imaging studies. Results show that the program can be used to assess these performances. Also the variations in performance parameters can be assessed due to the induced

  15. Gamma camera based FDG PET in oncology

    Park, C. H.

    2002-01-01

    Positron Emission Tomography(PET) was introduced as a research tool in the 1970s and it took about 20 years before PET became an useful clinical imaging modality. In the USA, insurance coverage for PET procedures in the 1990s was the turning point, I believe, for this progress. Initially PET was used in neurology but recently more than 80% of PET procedures are in oncological applications. I firmly believe, in the 21st century, one can not manage cancer patients properly without PET and PET is very important medical imaging modality in basic and clinical sciences. PET is grouped into 2 categories; conventional (c) and gamma camera based ( CB ) PET. CB PET is more readily available utilizing dual-head gamma cameras and commercially available FDG to many medical centers at low cost to patients. In fact there are more CB PET in operation than cPET in the USA. CB PET is inferior to cPET in its performance but clinical studies in oncology is feasible without expensive infrastructures such as staffing, rooms and equipments. At Ajou university Hospital, CBPET was installed in late 1997 for the first time in Korea as well as in Asia and the system has been used successfully and effectively in oncological applications. Our was the fourth PET operation in Korea and I believe this may have been instrumental for other institutions got interested in clinical PET. The following is a brief description of our clinical experience of FDG CBPET in oncology

  16. Development of gamma camera and application to decontamination

    Yoshida, Akira; Moro, Eiji; Takahashi, Isao

    2013-01-01

    A gamma camera has been developed to support recovering from the contamination caused by the accident of Fukushima Dai-ichi Nuclear Power Plant of Tokyo Electric Power Company. The gamma camera enables recognition of the contamination by visualizing radioactivity. The gamma camera has been utilized for risk communication (explanation to community resident) at local governments in Fukushima. From now on, the gamma camera will be applied to solve decontaminations issues; improving efficiency of decontamination, visualizing the effect of decontamination work and reducing radioactive waste. (author)

  17. Portable mini gamma camera for medical applications

    Porras, E; Benlloch, J M; El-Djalil-Kadi-Hanifi, M; López, S; Pavon, N; Ruiz, J A; Sánchez, F; Sebastiá, A

    2002-01-01

    A small, portable and low-cost gamma camera for medical applications has been developed and clinically tested. This camera, based on a scintillator crystal and a Position Sensitive Photo-Multiplier Tube, has a useful field of view of 4.6 cm diameter and provides 2.2 mm of intrinsic spatial resolution. Its mobility and light weight allow to reach the patient from any desired direction. This camera images small organs with high efficiency and so addresses the demand for devices of specific clinical applications. In this paper, we present the camera and briefly describe the procedures that have led us to choose its configuration and the image reconstruction method. The clinical tests and diagnostic capability are also presented and discussed.

  18. Batch extractive distillation for high purity methanol

    Zhang Weijiang; Ma Sisi

    2006-01-01

    In this paper, the application in chemical industry and microelectronic industry, market status and the present situation of production of high purity methanol at home and abroad were introduced firstly. Purification of industrial methanol for high purity methanol is feasible in china. Batch extractive distillation is the best separation technique for purification of industrial methanol. Dimethyl sulfoxide was better as an extractant. (authors)

  19. Characterization of segmented large volume, high purity germanium detectors

    Bruyneel, B. [Koeln Univ. (Germany). Inst. fuer Kernphysik

    2006-07-01

    {gamma}-ray tracking in future HPGe arrays like AGATA will rely on pulse shape analysis (PSA) of multiple {gamma}-interactions. For this purpose, a simple and fast procedure was developed which enabled the first full characterization of a segmented large volume HPGe detector. An analytical model for the hole mobility in a Ge crystal lattice was developed to describe the hole drift anisotropy with experimental velocity values along the crystal axis as parameters. The new model is based on the drifted Maxwellian hole distribution in Ge. It is verified by reproducing successfully experimental longitudinal hole anisotropy data. A comparison between electron and hole mobility shows large differences for the longitudinal and tangential velocity anisotropy as a function of the electrical field orientation. Measurements on a 12 fold segmented, n-type, large volume, irregular shaped HPGe detector were performed in order to determine the parameters of anisotropic mobility for electrons and holes as charge carriers created by {gamma}-ray interactions. To characterize the electron mobility the complete outer detector surface was scanned in small steps employing photopeak interactions at 60 keV. A precise measurement of the hole drift anisotropy was performed with 356 keV rays. The drift velocity anisotropy and crystal geometry cause considerable rise time differences in pulse shapes depending on the position of the spatial charge carrier creation. Pulse shapes of direct and transient signals are reproduced by weighting potential calculations with high precision. The measured angular dependence of rise times is caused by the anisotropic mobility, crystal geometry, changing field strength and space charge effects. Preamplified signals were processed employing digital spectroscopy electronics. Response functions, crosstalk contributions and averaging procedures were taken into account implying novel methods due to the segmentation of the Ge-crystal and the digital electronics. The results are relevant for the future {gamma}-ray tracking detectors where high precision of position information of single {gamma}-ray interactions is required. The high accuracy in simulation enabled very high position resolution using PSA. The first application of this technique in a real experiment aimed at the correction for crystal bending imperfections in a Bragg-spectrometer. A position resolution of {sigma}{sub x}=1.4 mm was achieved with 184 keV gamma rays employing the fully characterized detector. By careful characterization of the electronic noise, this result is expected to improve further upon use of optimized filters. (orig.)

  20. Characterization of segmented large volume, high purity germanium detectors

    Bruyneel, B.

    2006-01-01

    γ-ray tracking in future HPGe arrays like AGATA will rely on pulse shape analysis (PSA) of multiple γ-interactions. For this purpose, a simple and fast procedure was developed which enabled the first full characterization of a segmented large volume HPGe detector. An analytical model for the hole mobility in a Ge crystal lattice was developed to describe the hole drift anisotropy with experimental velocity values along the crystal axis as parameters. The new model is based on the drifted Maxwellian hole distribution in Ge. It is verified by reproducing successfully experimental longitudinal hole anisotropy data. A comparison between electron and hole mobility shows large differences for the longitudinal and tangential velocity anisotropy as a function of the electrical field orientation. Measurements on a 12 fold segmented, n-type, large volume, irregular shaped HPGe detector were performed in order to determine the parameters of anisotropic mobility for electrons and holes as charge carriers created by γ-ray interactions. To characterize the electron mobility the complete outer detector surface was scanned in small steps employing photopeak interactions at 60 keV. A precise measurement of the hole drift anisotropy was performed with 356 keV rays. The drift velocity anisotropy and crystal geometry cause considerable rise time differences in pulse shapes depending on the position of the spatial charge carrier creation. Pulse shapes of direct and transient signals are reproduced by weighting potential calculations with high precision. The measured angular dependence of rise times is caused by the anisotropic mobility, crystal geometry, changing field strength and space charge effects. Preamplified signals were processed employing digital spectroscopy electronics. Response functions, crosstalk contributions and averaging procedures were taken into account implying novel methods due to the segmentation of the Ge-crystal and the digital electronics. The results are relevant for the future γ-ray tracking detectors where high precision of position information of single γ-ray interactions is required. The high accuracy in simulation enabled very high position resolution using PSA. The first application of this technique in a real experiment aimed at the correction for crystal bending imperfections in a Bragg-spectrometer. A position resolution of σ x =1.4 mm was achieved with 184 keV gamma rays employing the fully characterized detector. By careful characterization of the electronic noise, this result is expected to improve further upon use of optimized filters. (orig.)

  1. Dynamic imaging with coincidence gamma camera

    Elhmassi, Ahmed

    2008-01-01

    In this paper we develop a technique to calculate dynamic parameters from data acquired using gamma-camera PET (gc PET). Our method is based on an algorithm development for dynamic SPECT, which processes all decency projection data simultaneously instead of reconstructing a series of static images individually. The algorithm was modified to account for the extra data that is obtained with gc PET (compared with SPEC). The method was tested using simulated projection data for both a SPECT and a gc PET geometry. These studies showed the ability of the code to reconstruct simulated data with a varying range of half-lives. The accuracy of the algorithm was measured in terms of the reconstructed half-life and initial activity for the simulated object. The reconstruction of gc PET data showed improvement in half-life and activity compared to SPECT data of 23% and 20%, respectively (at 50 iterations). The gc PET algorithm was also tested using data from an experimental phantom and finally, applied to a clinical dataset, where the algorithm was further modified to deal with the situation where the activity in certain pixels decreases and then increases during the acquisition. (author)

  2. The use of a portable gamma camera for preoperative lymphatic mapping: a comparison with a conventional gamma camera

    Vidal-Sicart, Sergi; Paredes, Pilar [Hospital Clinic Barcelona, Nuclear Medicine Department (CDIC), Barcelona (Spain); Institut d' Investigacio Biomedica Agusti Pi Sunyer (IDIBAPS), Barcelona (Spain); Vermeeren, Lenka; Valdes-Olmos, Renato A. [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital (NKI-AVL), Nuclear Medicine Department, Amsterdam (Netherlands); Sola, Oriol [Hospital Clinic Barcelona, Nuclear Medicine Department (CDIC), Barcelona (Spain)

    2011-04-15

    Planar lymphoscintigraphy is routinely used for preoperative sentinel node visualization, but large gamma cameras are not always available. We evaluated the reproducibility of lymphatic mapping with a smaller and portable gamma camera. In two centres, 52 patients with breast cancer received preoperative lymphoscintigraphy with a conventional gamma camera with a field of view of 40 x 40 cm. Static anterior and lateral images were performed at 15 min, 2 h and 4 h after injection of the radiotracer ({sup 99m}Tc-nanocolloid). At 2 h after injection, anterior and oblique images were also performed with a portable gamma camera (Sentinella, Oncovision) positioned to obtain a field of view of 20 x 20 cm. Visualization of lymphatic drainage on conventional images and images with the portable device were compared for number of nodes depicted, their intensity and localization of sentinel nodes. The images performed with the conventional gamma camera depicted sentinel nodes in 94%, while the portable gamma camera showed drainage in 73%. There was however no significant difference in visualization between the two devices when a lead shield was used to mask the injection area in 43 patients (95 vs 88%, p = 0.25). Second-echelon nodes were visualized in 62% of the patients with the conventional gamma camera and in 29% of the cases with the portable gamma camera. Preoperative imaging with a portable gamma camera fitted with a pinhole collimator to obtain a field of view of 20 x 20 cm is able to depict sentinel nodes in 88% of the cases, if a lead shield is used to mask the injection site. This device may be useful in centres without the possibility to perform a preoperative image. (orig.)

  3. The use of a portable gamma camera for preoperative lymphatic mapping: a comparison with a conventional gamma camera

    Vidal-Sicart, Sergi; Paredes, Pilar; Vermeeren, Lenka; Valdes-Olmos, Renato A.; Sola, Oriol

    2011-01-01

    Planar lymphoscintigraphy is routinely used for preoperative sentinel node visualization, but large gamma cameras are not always available. We evaluated the reproducibility of lymphatic mapping with a smaller and portable gamma camera. In two centres, 52 patients with breast cancer received preoperative lymphoscintigraphy with a conventional gamma camera with a field of view of 40 x 40 cm. Static anterior and lateral images were performed at 15 min, 2 h and 4 h after injection of the radiotracer ( 99m Tc-nanocolloid). At 2 h after injection, anterior and oblique images were also performed with a portable gamma camera (Sentinella, Oncovision) positioned to obtain a field of view of 20 x 20 cm. Visualization of lymphatic drainage on conventional images and images with the portable device were compared for number of nodes depicted, their intensity and localization of sentinel nodes. The images performed with the conventional gamma camera depicted sentinel nodes in 94%, while the portable gamma camera showed drainage in 73%. There was however no significant difference in visualization between the two devices when a lead shield was used to mask the injection area in 43 patients (95 vs 88%, p = 0.25). Second-echelon nodes were visualized in 62% of the patients with the conventional gamma camera and in 29% of the cases with the portable gamma camera. Preoperative imaging with a portable gamma camera fitted with a pinhole collimator to obtain a field of view of 20 x 20 cm is able to depict sentinel nodes in 88% of the cases, if a lead shield is used to mask the injection site. This device may be useful in centres without the possibility to perform a preoperative image. (orig.)

  4. PC-AT to gamma camera interface Anugami-S

    Bhattacharya, Sadhana; Sonalkar, S.Y.; Kataria, S.K.

    2000-01-01

    The gamma camera interface ANUGAMI-S is an image acquisition system used in nuclear medicine centres and hospitals. The state of the art design of the interface provides quality improvement in addition to image acquisition, by applying on-line uniformity correction which is very essential for gamma camera applications in nuclear medicine. The improvement in the quality of the image has been achieved by image acquisition in positionally varying and sliding energy window. It supports all acquisition modes viz. static, dynamic and gated acquisition modes with and without uniformity correction. The user interface provides the acquisition in various user selectable parameters with image display and related acquisition parameter display. It is a universal system which provides a modern, cost effective and easily maintainable solution for interfacing any gamma camera to PC or upgradation of analog gamma camera. The paper describes the system details and gated acquisition achieved on the present system. (author)

  5. Quality control of plane and tomographic gamma cameras

    Moretti, J.L.; Roussi, A.

    1993-01-01

    In this article, the authors present different methods of gamma camera quality control in matters of uniformity, spatial resolution, spatial linearity, sensitivity, energy resolution, counting rate performance, SPECT parameters. The authors refer mainly to NEMA standards. 14 figs., 8 tabs

  6. PC-AT to gamma camera interface ANUGAMI-S

    Bhattacharya, Sadhana; Gopalakrishnan, K.R.

    1997-01-01

    PC-AT to gamma camera interface is an image acquisition system used in nuclear medicine centres and hospitals. The interface hardware and acquisition software have been designed and developed to meet most of the routine clinical applications using gamma camera. The state of the art design of the interface provides quality improvement in addition to image acquisition, by applying on-line uniformity correction which is very essential for gamma camera applications in nuclear medicine. The improvement in the quality of the image has been achieved by image acquisition in positionally varying and sliding energy window. It supports all acquisition modes viz. static, dynamic and gated acquisition modes with and without uniformity correction. The user interface provides the acquisition in various user selectable frame sizes, orientation and colour palettes. A complete emulation of camera console has been provided along with persistence scope and acquisition parameter display. It is a universal system which provides a modern, cost effective and easily maintainable solution for interfacing any gamma camera to PC or upgradation of analog gamma camera. (author). 4 refs., 3 figs

  7. Spectroscopic gamma camera for use in high dose environments

    Ueno, Yuichiro, E-mail: yuichiro.ueno.bv@hitachi.com [Research and Development Group, Hitachi, Ltd., Hitachi-shi, Ibaraki-ken 319-1221 (Japan); Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi [Research and Development Group, Hitachi, Ltd., Hitachi-shi, Ibaraki-ken 319-1221 (Japan); Fujishima, Yasutake; Kometani, Yutaka [Hitachi Works, Hitachi-GE Nuclear Energy, Ltd., Hitachi-shi, Ibaraki-ken (Japan); Suzuki, Yasuhiko [Measuring Systems Engineering Dept., Hitachi Aloka Medical, Ltd., Ome-shi, Tokyo (Japan); Umegaki, Kikuo [Faculty of Engineering, Hokkaido University, Sapporo-shi, Hokkaido (Japan)

    2016-06-21

    We developed a pinhole gamma camera to measure distributions of radioactive material contaminants and to identify radionuclides in extraordinarily high dose regions (1000 mSv/h). The developed gamma camera is characterized by: (1) tolerance for high dose rate environments; (2) high spatial and spectral resolution for identifying unknown contaminating sources; and (3) good usability for being carried on a robot and remotely controlled. These are achieved by using a compact pixelated detector module with CdTe semiconductors, efficient shielding, and a fine resolution pinhole collimator. The gamma camera weighs less than 100 kg, and its field of view is an 8 m square in the case of a distance of 10 m and its image is divided into 256 (16×16) pixels. From the laboratory test, we found the energy resolution at the 662 keV photopeak was 2.3% FWHM, which is enough to identify the radionuclides. We found that the count rate per background dose rate was 220 cps h/mSv and the maximum count rate was 300 kcps, so the maximum dose rate of the environment where the gamma camera can be operated was calculated as 1400 mSv/h. We investigated the reactor building of Unit 1 at the Fukushima Dai-ichi Nuclear Power Plant using the gamma camera and could identify the unknown contaminating source in the dose rate environment that was as high as 659 mSv/h.

  8. Effect of scatter media on small gamma camera imaging characteristics

    Ser, H. K.; Choi, Y.; Yim, K. C.

    2001-01-01

    Effect of scatter media materials and thickness, located between radioactivity and small gamma camera, on imaging characteristics was evaluated. The small gamma camera developed for breast imaging was consisted of collimator, NaI(TI) crystal (60x60x6 mm 3 ). PSPMT (position sensitive photomultiplier tube), NIMs and personal computer. Monte Carlo simulation was performed to evaluate the system sensitivity with different scatter media thickness (0∼8 cm) and materials (air and acrylie) with parallel hole collimator and diverging collimator. The sensitivity and spatial resolution was measured using the small gamma camera with the same condition applied to the simulation. Counts was decreased by 10% (air) and 54% (acrylic) with the parallel hole collimator and by 35% (air) and 63% (acrylic) with the diverging collimator. Spatial resolution was decreased as increasing the thickness of scatter media. This study substantiate the importance of a gamma camera positioning and the minimization of the distance between detector and target lesion in the clinical application of a gamma camera

  9. Low-cost high purity production

    Kapur, V. K.

    1978-01-01

    Economical process produces high-purity silicon crystals suitable for use in solar cells. Reaction is strongly exothermic and can be initiated at relatively low temperature, making it potentially suitable for development into low-cost commercial process. Important advantages include exothermic character and comparatively low process temperatures. These could lead to significant savings in equipment and energy costs.

  10. Development and evaluation of a Gamma Camera tuning system

    Arista Romeu, E. J.; Diaz Garcia, A.; Osorio Deliz, J. F.

    2015-01-01

    Correct operation of conventional analogue Gamma Cameras implies a good conformation of the position signals that correspond to a specific photo-peak of the radionuclide of interest. In order to achieve this goal the energy spectrum from each photo multiplier tube (PMT) has to be set within the same energy window. For this reason a reliable tuning system is an important part of all gamma cameras processing systems. In this work is being tested and evaluated a new prototype of tuning card that was developed and setting up for this purpose. The hardware and software of the circuit allow the regulation if each PMT high voltage. By this means a proper gain control for each of them is accomplished. The Tuning Card prototype was simulated in a virtual model and its satisfactory operation was proven in a Siemens Orbiter Gamma Camera. (Author)

  11. Gamma camera image processing and graphical analysis mutual software system

    Wang Zhiqian; Chen Yongming; Ding Ailian; Ling Zhiye; Jin Yongjie

    1992-01-01

    GCCS gamma camera image processing and graphical analysis system is a special mutual software system. It is mainly used to analyse various patient data acquired from gamma camera. This system is used on IBM PC, PC/XT or PC/AT. It consists of several parts: system management, data management, device management, program package and user programs. The system provides two kinds of user interfaces: command menu and command characters. It is easy to change and enlarge this system because it is best modularized. The user programs include almost all the clinical protocols used now

  12. Thermal conductivity of high purity vanadium

    Jung, W.D.

    1975-01-01

    The thermal conductivity, Seebeck coefficient, and electrical resistivity of four high-purity vanadium samples were measured over the temperature range 5 to 300 0 K. The highest purity sample had a resistance ratio (rho 273 /rho 4 . 2 ) of 1524. The highest purity sample had a thermal conductivity maximum of 920 W/mK at 9 0 K and had a thermal conductivity of 35 W/mK at room temperature. At low temperatures, the thermal resistivity was limited by the scattering of electrons by impurities and phonons. The thermal resistivity of vanadium departed from Matthiessen's rule at low temperatures. The electrical resistivity and Seebeck coefficient of high purity vanadium showed no anomalous behavior above 130 0 K. The intrinsic electrical resistivity at low temperatures was due primarily to interband scattering of electrons. The Seebeck coefficient was positive from 10 to 240 0 K and had a maximum which was dependent upon sample purity

  13. High purity radioactive beams at the bevalac

    Alonso, J.R.; Chatterjee, A.; Tobias, C.A.

    1979-03-01

    Peripheral nuclear fragmentation reactions of primary Bevalac heavy ion beams are used to produce secondary beams of radioactive nuclei. The large cross section and small deflection of the projectile fragments lead to high production and delivery efficiency for these beams. Dispersive beam transport allows good separation and purification of the desired secondary beams. 11 C and 19 Ne beams of high purity and good intensity (almost 0.2% of the primary beam current) are presently being used for biomedical experiments

  14. Programmable electronic system for analog and digital gamma cameras modernization

    Osorio Deliz, J. F.; Diaz Garcia, A.; Arista Omeu, E. J.

    2013-01-01

    At present the use of analog and digital gamma cameras is continuously increasing in developing countries. Many of them still largely rely in old hardware electronics, which in many cases limits their use in actual nuclear medicine diagnostic studies. For this reason worldwide there are different medical equipment manufacturing companies engaged into partial or total Gamma Cameras modernization. Nevertheless in several occasions acquisition prices are not affordable for developing countries. This work describes the basic features of a programmable electronic system that allows improving acquisitions functions and processing of analog and digital gamma cameras. This system is based on an electronic board for the acquisition and digitization of nuclear pulses which have been generated by gamma camera detector. It comprises a hardware interface with PC and the associated software to fully signal processing. Signal shaping and image processing are included. The extensive use of reference tables in the processing and signal imaging software allowed the optimization of the processing speed. Time design and system cost were also decreased. (Author)

  15. Method of high purity silane preparation

    Tsuo, Y. Simon; Belov, Eugene P.; Gerlivanov, Vadim G.; Zadde, Vitali V.; Kleschevnikova, Solomonida I.; Korneev, Nikolai N.; Lebedev, Eugene N.; Pinov, Akhsarbek B.; Ryabenko, Eugene A.; Strebkov, Dmitry S.; Chernyshev, Eugene A.

    2000-01-01

    A process for the preparation of high purity silane, suitable for forming thin layer silicon structures in various semiconductor devices and high purity poly- and single crystal silicon for a variety of applications, is provided. Synthesis of high-purity silane starts with a temperature assisted reaction of metallurgical silicon with alcohol in the presence of a catalyst. Alcoxysilanes formed in the silicon-alcohol reaction are separated from other products and purified. Simultaneous reduction and oxidation of alcoxysilanes produces gaseous silane and liquid secondary products, including, active part of a catalyst, tetra-alcoxysilanes, and impurity compounds having silicon-hydrogen bonds. Silane is purified by an impurity adsorption technique. Unreacted alcohol is extracted and returned to the reaction with silicon. Concentrated mixture of alcoxysilanes undergoes simultaneous oxidation and reduction in the presence of a catalyst at the temperature -20.degree. C. to +40.degree. C. during 1 to 50 hours. Tetra-alcoxysilane extracted from liquid products of simultaneous oxidation and reduction reaction is directed to a complete hydrolysis. Complete hydrolysis of tetra-alcoxysilane results in formation of industrial silica sol and alcohol. Alcohol is dehydrated by tetra-alcoxysilane and returned to the reaction with silicon.

  16. Preparation of high-purity cerium nitrate

    Avila, Daniela Moraes; Silva Queiroz, Carlos Alberto da; Santos Mucillo, Eliana Navarro dos

    1995-01-01

    The preparation of high-purity cerium nitrate has been carried out Cerium oxide has been prepared by fractioned precipitation and ionic exchange techniques, using a concentrate with approximately 85% of cerium oxide from NUCLEMON as raw material. Five sequential ion-exchange columns with a retention capacity of 170 g each have been used. The ethylenediamine-tetraacetic acid (EDTA) was used as eluent. The cerium content has been determined by gravimetry and iodometry techniques. The resulting cerium oxide has a purity > 99%. This material was transformed in cerium nitrate to be used as precursor for the preparation of Zirconia-ceria ceramics by the coprecipitation technique. (author)

  17. Preserving high-purity 233U

    Krichinsky, Alan; Giaquinto, Joe; Canaan, Doug

    2016-01-01

    The MARC X Conference hosted a workshop for the scientific community to communicate needs for high-purity 233 U and its by-products in order to preserve critical items otherwise slated for downblending and disposal. Currently, only small portions of the U.S. holdings of separated 233 U are being preserved. However, many additional kilograms of 233 U (>97 % pure) still are destined to be disposed, and it is unlikely that this material will ever be replaced due to a lack of operating production capability. Summaries of information conveyed at the workshop and feedback obtained from the scientific community are presented herein. (author)

  18. Performance characteristics of ZLC 37 Siemens gamma camera

    Abdelgadir, Wafaa Abdelrahman [Department of Physics, Faculty of Science, University of Khartoum, Khartoum (Sudan)

    1994-04-01

    The relationships between the ZLC 37 Siemens {gamma} camera parameters (energy resolution, plane sensitivity, intrinsic uniformity, intrinsic resolution, system uniformity and system resolution) and diagnostic imaging performance was investigated. These parameters when computers when compared with internationally published data showed that the ZLC 37 Siemens {gamma} cameras is in good operative conditions. The effect of the scattering media and WW on the spatial resolution, when the distance is kept fixed were investigated. Comparison of resolution for the media (air, water, water + radioactivity) when using WW (10, 15,20%) showed that the resolution is best for air, better for water and worse for water + radioactivity up to a concentration of 8% for a 10% WW. (Author) 28 refs. , 10 tabs. , 22 figs. Also available from the Department of Physics, Faculty of Science, University of Khartoum, Khartoum (SD)

  19. Gamma camera investigations using an on-line computer system

    Vikterloef, K.J.; Beckman, K.-W.; Berne, E.; Liljenfors, B.

    1974-01-01

    A computer system for use with a gamma camera has been developed by Oerebro Regional Hospital and Nukab AB using a PDP 8/e with a 12K core memory connected to a Selektronik gamma camera. It is possible to register, without loss, pictures of high (5kcps) pulse frequency, two separate channels with identical coordinates, fast dynamic functions down to 5 pictures/second, and to perform statistical smoothing and subtraction of two separate pictures. Experience has shown these possibilities to be so valuable that one has difficulty in thinking of a scanning system without them. This applies not only to sophisticated investigations, e.g. dual isotope registration, but also in conventional scanning for avoiding false positive interpretations and increasing the precision. It is possible at relatively low cost to add a dosage planning system. (JIW)

  20. A SPECT demonstrator—revival of a gamma camera

    Valastyán, I.; Kerek, A.; Molnár, J.; Novák, D.; Végh, J.; Emri, M.; Trón, L.

    2006-07-01

    A gamma camera has been updated and converted to serve as a demonstrator for educational purposes. The gantry and the camera head were the only part of the system that remained untouched. The main reason for this modernization was to increase the transparency of the gamma camera by partitioning the different logical building blocks of the system and thus providing access for inspection and improvements throughout the chain. New data acquisition and reconstruction software has been installed. By taking these measures, the camera is now used in education and also serves as a platform for tests of new hardware and software solutions. The camera is also used to demonstrate 3D (SPECT) imaging by collecting 2D projections from a rotatable cylindrical phantom. Since the camera head is not attached mechanically to the phantom, the effect of misalignment between the head and the rotation axis of the phantom can be studied.

  1. A SPECT demonstrator-revival of a gamma camera

    Valastyan, I.; Kerek, A.; Molnar, J.; Novak, D.; Vegh, J.; Emri, M.; Tron, L.

    2006-01-01

    A gamma camera has been updated and converted to serve as a demonstrator for educational purposes. The gantry and the camera head were the only part of the system that remained untouched. The main reason for this modernization was to increase the transparency of the gamma camera by partitioning the different logical building blocks of the system and thus providing access for inspection and improvements throughout the chain. New data acquisition and reconstruction software has been installed. By taking these measures, the camera is now used in education and also serves as a platform for tests of new hardware and software solutions. The camera is also used to demonstrate 3D (SPECT) imaging by collecting 2D projections from a rotatable cylindrical phantom. Since the camera head is not attached mechanically to the phantom, the effect of misalignment between the head and the rotation axis of the phantom can be studied

  2. Acquisition of gamma camera and physiological data by computer

    Hack, S.N.; Chang, M.; Line, B.R.; Cooper, J.A.; Robeson, G.H.

    1986-01-01

    We have designed, implemented, and tested a new Research Data Acquisition System (RDAS) that permits a general purpose digital computer to acquire signals from both gamma camera sources and physiological signal sources concurrently. This system overcomes the limited multi-source, high speed data acquisition capabilities found in most clinically oriented nuclear medicine computers. The RDAS can simultaneously input signals from up to four gamma camera sources with a throughput of 200 kHz per source and from up to eight physiological signal sources with an aggregate throughput of 50 kHz. Rigorous testing has found the RDAS to exhibit acceptable linearity and timing characteristics. In addition, flood images obtained by this system were compared with flood images acquired by a commercial nuclear medicine computer system. National Electrical Manufacturers Association performance standards of the flood images were found to be comparable

  3. A triple GEM gamma camera for medical application

    Anulli, F. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Balla, A. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Bencivenni, G. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Corradi, G. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); D' Ambrosio, C. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Domenici, D. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Felici, G. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Gatta, M. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Morone, M.C. [Dipartimento di Biopatologia e Diagnostica per immagini, Universita di Roma Tor Vergata (Italy); INFN - Sezione di Roma Tor Vergata (Italy); Murtas, F. [Laboratori Nazionali di Frascati INFN, Frascati (Italy)]. E-mail: fabrizio.murtas@lnf.infn.it; Schillaci, O. [Dipartimento di Biopatologia e Diagnostica per immagini, Universita di Roma Tor Vergata (Italy)

    2007-03-01

    A Gamma Camera for medical applications 10x10cm{sup 2} has been built using a triple GEM chamber prototype. The photon converters placed in front of the three GEM foils, has been realized with different technologies. The chamber, High Voltage supplied with a new active divider made in Frascati, is readout through 64 pads, 1mm{sup 2} wide, organized in a row of 8cm long, with LHCb ASDQ chip. This Gamma Camera can be used both for X-ray movie and PET-SPECT imaging; this chamber prototype is placed in a scanner system, creating images of 8x8cm{sup 2}. Several measurements have been performed using phantom and radioactive sources of Tc99m(140keV) and Na22(511keV). Results on spatial resolution and image reconstruction are presented.

  4. Evaluation of efficiency of a semiconductor gamma camera

    Otake, H; Takeuchi, Y

    2002-01-01

    We evaluation basic characteristics of a compact type semiconductor gamma camera (eZ-SCOPE AN) of Cadmium Zinc Telluride (CdZnTe). This new compact gamma camera has 256 semiconductors representing the same number of pixels. Each semiconductor is 2 mm square and is located in 16 lines and rows on the surface of the detector. The specific performance characteristics were evaluated in the study referring to National Electrical Manufactures Association (NEMA) standards; intrinsic energy resolution, intrinsic count rate performance, integral uniformity, system planar sensitivity, system spatial resolution, and noise to the neighboring pixels. The intrinsic energy resolution measured 5.7% as full width half maximum (FWHM). The intrinsic count rate performance ranging from 17 kcps to 1,285 kcps was evaluated, but the highest intrinsic count rate was not observed. Twenty percents count loss was recognized at 1,021 kcps. The integral uniformity was 1.3% with high sensitivity collimator. The system planar sensitivity w...

  5. Is it practical to use the gamma camera dead time

    Morin, P.P.; Morin, J.F.; Caroff, J.; Lahellec, M.; Savina, A.

    1975-01-01

    The linearity of gamma camera counting is an essential feature for users engaged in quantitative dynamic studies. Instead of defining this quality by the usual dead time, the disadvantages of which are reported, it is proposed to use the experimental count rate giving 10% loss. It is shown that by proceeding in this way all ambiguity would be abolished, where both the counting linearity itself and its relation to sensitivity are concerned [fr

  6. Biomedical image acquisition system using a gamma camera

    Jara B, A.T.; Sevillano, J.; Del Carpio S, J.A.

    2003-01-01

    A gamma camera images PC acquisition board has been developed. The digital system has been described using VHDL and has been synthesized and implemented in a Altera Max7128S CPLD and two PALs 16L8. The use of programmable-logic technologies has afforded a higher scale integration and a reduction of the digital delays and also has allowed us to modify and bring up to date the entire digital design easily. (orig.)

  7. Standardization of test conditions for gamma camera performance measurement

    Jordan, K.

    1982-02-01

    The way of measuring gamma camera performance is to use point sources or flood sources in air, often in combination with bar phantoms. This method has nothing in common with the use of a camera in clinical practice. Particularly in the case of low energy emitters, like Tc-99m, the influence of scattered radiation over the performance of cameras is very high. The IEC document 'Characteristics and test conditions of radionuclide imaging devices' is discussed

  8. Design and tests of a portable mini gamma camera

    Sanchez, F.; Benlloch, J.M.; Escat, B.; Pavon, N.; Porras, E.; Kadi-Hanifi, D.; Ruiz, J.A.; Mora, F.J.; Sebastia, A.

    2004-01-01

    Design optimization, manufacturing, and tests, both laboratory and clinical, of a portable gamma camera for medical applications are presented. This camera, based on a continuous scintillation crystal and a position-sensitive photomultiplier tube, has an intrinsic spatial resolution of ≅2 mm, an energy resolution of 13% at 140 keV, and linearities of 0.28 mm (absolute) and 0.15 mm (differential), with a useful field of view of 4.6 cm diameter. Our camera can image small organs with high efficiency and so it can address the demand for devices of specific clinical applications like thyroid and sentinel node scintigraphy as well as scintimammography and radio-guided surgery. The main advantages of the gamma camera with respect to those previously reported in the literature are high portability, low cost, and weight (2 kg), with no significant loss of sensitivity and spatial resolution. All the electronic components are packed inside the minigamma camera, and no external electronic devices are required. The camera is only connected through the universal serial bus port to a portable personal computer (PC), where a specific software allows to control both the camera parameters and the measuring process, by displaying on the PC the acquired image on 'real time'. In this article, we present the camera and describe the procedures that have led us to choose its configuration. Laboratory and clinical tests are presented together with diagnostic capabilities of the gamma camera

  9. Neutron activation analysis of high purity substances

    Gil'bert, Eh.N.

    1987-01-01

    Peculiarities of neutron-activation analysis (NAA) of high purity substances are considered. Simultaneous determination of a wide series of elements, high sensitivity (the lower bound of determined contents 10 -9 -10 -10 %), high selectivity and accuracy (Sr=0.10-0.15, and may be decreased up to 0.001), possibility of analysis of the samples from several micrograms to hundreds of grams, simplicity of calibration may be thought NAA advantages. Questions of accounting of NAA systematic errors associated with the neutron flux screening by the analysed matrix and with production of radionuclides of determined elements from accompanying elements according to concurrent nuclear reactions, as well as accounting of errors due to self-absorption of recorded radiation by compact samples, are considered

  10. Neutron activation analysis of high purity tellurium

    Gil'bert, Eh.N.; Verevkin, G.V.; Obrazovskij, E.G.; Shatskaya, S.S.

    1980-01-01

    A scheme of neutron activation analysis of high purity tellurium is developed. Weighed amount of Te (0.5 g) is irradiated for 20-40 hr in the flux of 2x10 13 neutron/(cm 2 xs). After decomposition of the sample impurities of gold and palladium are determined by the extraction with organic sulphides. Tellurium separation from the remaining impurities is carried out by the extraction with monothiobenzoic acid from weakly acidic HCl solutions in the presence of iodide-ions, suppressing silver extraction. Remaining impurity elements in the refined product are determined γ-spectrometrically. The method allows to determine 34 impurities with determination limits 10 -6 -10 -11 g

  11. Upgrading of analogue gamma cameras with PC based computer system

    Fidler, V.; Prepadnik, M.

    2002-01-01

    Full text: Dedicated nuclear medicine computers for acquisition and processing of images from analogue gamma cameras in developing countries are in many cases faulty and technologically obsolete. The aim of the upgrading project of International Atomic Energy Agency (IAEA) was to support the development of the PC based computer system which would cost 5.000 $ in total. Several research institutions from different countries (China, Cuba, India and Slovenia) were financially supported in this development. The basic demands for the system were: one acquisition card an ISA bus, image resolution up to 256x256, SVGA graphics, low count loss at high count rates, standard acquisition and clinical protocols incorporated in PIP (Portable Image Processing), on-line energy and uniformity correction, graphic printing and networking. The most functionally stable acquisition system tested on several international workshops and university clinics was the Slovenian one with a complete set of acquisition and clinical protocols, transfer of scintigraphic data from acquisition card to PC through PORT, count loss less than 1 % at count rate of 120 kc/s, improvement of integral uniformity index by a factor of 3-5 times, reporting, networking and archiving solutions for simple MS network or server oriented network systems (NT server, etc). More than 300 gamma cameras in 52 countries were digitized and put in the routine work. The project of upgrading the analogue gamma cameras yielded a high promotion of nuclear medicine in the developing countries by replacing the old computer systems, improving the technological knowledge of end users on workshops and training courses and lowering the maintenance cost of the departments. (author)

  12. Rapid objective measurement of gamma camera resolution using statistical moments.

    Hander, T A; Lancaster, J L; Kopp, D T; Lasher, J C; Blumhardt, R; Fox, P T

    1997-02-01

    An easy and rapid method for the measurement of the intrinsic spatial resolution of a gamma camera was developed. The measurement is based on the first and second statistical moments of regions of interest (ROIs) applied to bar phantom images. This leads to an estimate of the modulation transfer function (MTF) and the full-width-at-half-maximum (FWHM) of a line spread function (LSF). Bar phantom images were acquired using four large field-of-view (LFOV) gamma cameras (Scintronix, Picker, Searle, Siemens). The following factors important for routine measurements of gamma camera resolution with this method were tested: ROI placement and shape, phantom orientation, spatial sampling, and procedural consistency. A 0.2% coefficient of variation (CV) between repeat measurements of MTF was observed for a circular ROI. The CVs of less than 2% were observed for measured MTF values for bar orientations ranging from -10 degrees to +10 degrees with respect to the x and y axes of the camera acquisition matrix. A 256 x 256 matrix (1.6 mm pixel spacing) was judged sufficient for routine measurements, giving an estimate of the FWHM to within 0.1 mm of manufacturer-specified values (3% difference). Under simulated clinical conditions, the variation in measurements attributable to procedural effects yielded a CV of less than 2% in newer generation cameras. The moments method for determining MTF correlated well with a peak-valley method, with an average difference of 0.03 across the range of spatial frequencies tested (0.11-0.17 line pairs/mm, corresponding to 4.5-3.0 mm bars). When compared with the NEMA method for measuring intrinsic spatial resolution, the moments method was found to be within 4% of the expected FWHM.

  13. Clinical significance of gamma camera renography in chronic renal insufficiency

    Dudczak, R.; Frischauf, H.; Kletter, K.

    1980-01-01

    Gamma camera renography allows, together with renal imaging, an evaluation of individual renal function. For these examinations, I 123 orthoiodohippurate is preferred and most widely used. The results on patients with chronic renal insufficiency, including urologic and posttransplantation patients, are reported. Whereas the method is of clinical significance in evaluating posttransplantation complications and in assessing individual kidney function preoperatively in urology, as well as in monitoring therapeutic effects in the early period of renal disease, it is of limited diagnostic value in chronic renal insufficiency. In this latter regard, clinical and laboratory examinations are of primary importance. (author)

  14. A fast algorithm for computer aided collimation gamma camera (CACAO)

    Jeanguillaume, C.; Begot, S.; Quartuccio, M.; Douiri, A.; Franck, D.; Pihet, P.; Ballongue, P.

    2000-08-01

    The computer aided collimation gamma camera is aimed at breaking down the resolution sensitivity trade-off of the conventional parallel hole collimator. It uses larger and longer holes, having an added linear movement at the acquisition sequence. A dedicated algorithm including shift and sum, deconvolution, parabolic filtering and rotation is described. Examples of reconstruction are given. This work shows that a simple and fast algorithm, based on a diagonal dominant approximation of the problem can be derived. Its gives a practical solution to the CACAO reconstruction problem.

  15. What about getting physiological information into dynamic gamma camera studies

    Kiuru, A.; Nickles, R. J.; Holden, J. E.; Polcyn, R. E.

    1976-01-01

    A general technique has been developed for the multiplexing of time dependent analog signals into the individual frames of a gamma camera dynamic function study. A pulse train, frequency-modulated by the physiological signal, is capacitively coupled to the preamplifier servicing anyone of the outer phototubes of the camera head. These negative tail pulses imitate photoevents occuring at a point outside of the camera field of view, chosen to occupy a data cell in an unused corner of the computer-stored square image. By defining a region of interest around this cell, the resulting time-activity curve displays the physiological variable in temporal synchrony with the radiotracer distribution. (author)

  16. Energy independent uniformity improvement for gamma camera systems

    Lange, K.

    1979-01-01

    In a gamma camera system having an array of photomultiplier tubes for detecting scintillation events and preamplifiers connecting each tube to a weighting resistor matrix for determining the position coordinates of the events, means are provided for summing the signals from all photomultipliers to obtain the total energy of each event. In one embodiment, at least two different percentages of the summed voltage are developed and used to change the gain of the preamplifiers as a function of total energy when energies exceed specific levels to thereby obtain more accurate correspondence between the true coordinates of the event and its coordinates in a display

  17. Gamma camera system with composite solid state detector

    Gerber, M.S.; Miller, D.W.

    1977-01-01

    A composite solid-state detector is described for utilization within gamma cameras. The detector's formed of an array of detector crystals, the opposed surfaces of each of which are formed incorporating an impedance-derived configuration for determining one coordinate of the location of discrete impinging photons upon the detector. A combined read-out for all detectors within the composite array is achieved through a row and column interconnection of the impedance configurations. Utilizing the read-outs for respective sides of the discrete crystals, a resultant time-constant characteristic for the composite detector crystal array remains essentially that of individual crystal detectors

  18. PC based simulation of gamma camera for training of operating and maintenance staff

    Singh, B.; Kataria, S.K.; Samuel, A.M.

    2000-01-01

    Gamma camera- a sophisticated imaging system is used for functional assessment of biological subsystems/organs in nuclear medicine. The radioactive tracer attached to the native substance is injected into the patient. The distribution of radioactivity in the patient is imaged by the gamma camera. This report describes a PC based package for simulation of gamma cameras and effect of malfunctioning of its subsystems on images of different phantoms

  19. Simulation for photon detection in spectrometric system of high purity (HPGe) using MCNPX code

    Correa, Guilherme Jorge de Souza

    2013-01-01

    The Brazilian National Commission of Nuclear Energy defines parameters for classification and management of radioactive waste in accordance with the activity of materials. The efficiency of a detection system is crucial to determine the real activity of a radioactive source. When it's possible, the system's calibration should be performed using a standard source. Unfortunately, there are only a few cases that it can be done this way, considering the difficulty of obtaining appropriate standard sources for each type of measurement. So, computer simulations can be performed to assist in calculating of the efficiency of the system and, consequently, also auxiliary the classification of radioactive waste. This study aims to model a high purity germanium (HPGe) detector with MCNPX code, approaching the spectral values computationally obtained of the values experimentally obtained for the photopeak of 137 Cs. The approach will be made through changes in outer dead layer of the germanium crystal modeled. (author)

  20. Growth of high purity semiconductor epitaxial layers by liquid phase ...

    Unknown

    semiconductor materials in high purity form by liquid phase epitaxy (LPE) technique. Various possible sources of impurities in such ... reference to the growth of GaAs layers. The technique of growing very high purity layers ... the inner walls of the gas lines and (e) the containers for storing, handling and cleaning of the mate-.

  1. Recent developments in gamma camera technology for myocardial perfusion scintigraphy

    Bengel, Frank M.

    2010-01-01

    Economic pressure, competition from alternative modalities and an increasing awareness of patient radiation exposure have triggered a rapid development of novel technology for cardiac single-photon emission computed tomography (SPECT) in recent years. The trend clearly goes towards systems with higher sensitivity and resolution, and towards faster acquisition protocols. Those goals are achieved by various measures: On the one hand, several manufacturers have integrated novel semiconductor detector materials together with innovative collimators into dedicated cardiac scanners. On the other hand, new collimators and reconstruction algorithms have lead to increased speed and accuracy of conventional gamma cameras. Imaging times now can be reduced to as much as 10% of that of previous standard protocols, and/or injected activity can be reduced. This is achieved without loss of diagnostic accuracy. These novel developments are still in early phases of clinical implementation. Their potential for a profound change of the clinical practice of myocardial perfusion scintigraphy, however, becomes increasingly obvious. (orig.)

  2. Gamma camera system with improved means for correcting nonuniformity

    Lange, K.; Jeppesen, J.

    1979-01-01

    In a gamma camera system, means are provided for correcting nonuniformity or lack of correspondence between the positions of scintillations and their calculated and displayed by x-y coordinates. In an accumulation mode, pulse counts corresponding with scintillations in various areas of the radiation field are stored in memory locations corresponding with their locations in the radiation field. A uniform radiation source is presented to the detectors during the accumulation is interrupted at which time other locations have fewer counts in them. In the run mode, counts are stored in corresponding locations of a memory and these counts are compared continuously with those stored in the accumulation mode. Means are provided for injecting a number of counts during the run mode proportional to the difference between the counts accumulated during the accumulation mode in a given area increment and the counts that should have been obtained from a uniform source

  3. A new gamma camera for positron emission tomography

    Schotanus, P.

    1988-01-01

    This thesis describes the detection of annihiliation radiation employing a new principle: radiation is absorbed in a barium fluoride (BaF 2) crystal and the resulting scintillation light is detected in a multiwire proportional chamber filled with a photsensitive vapour. The application of such a detector for PET is new; the use of a high density fast scintillator in combination with a low pressure wire chamber offers a good detection efficiency and permits high count rates because of the small dead time. In this work, the physical background of the above detection mechanism is explored and the performance parameters of a gamma camera using this new principle, are determined. Furthermore, a comprehensive research on the scintillation mechanism and physical characteristics of the increasingly popular BaF 2 scintillator is presented. Also, a new class of ultraviolet (UV) scintillation materials, consisting of rare earth doped fluorides, is introduced. (author). 211 refs.; 30 figs.; 17 tabs

  4. Quality control of the gamma camera/computer interface

    Busemann-Sokole, E.

    1983-01-01

    Reporting on the conference mentioned, the author indicates that technical inspection of the gamma camera and the attached computer each by themselves is not sufficient. The parts of the interface and the hardware or software can contain sources of error. In order to obtain the best diagnostic image a number of control measurements are recommended dealing with image intensifying, intensifier offset, linearity of transformation, exclusion of 'data drop' or 'bit drop', 2-pulse timing, correct response with different counting rates, and response to triggers (electrocardiogram). The last and most important recommendation is to record in writing particulars of each inspection and control measurement, particulars and solutions of problems and modifications in hardware and software. (Auth.)

  5. Inter-laboratory comparison study of gamma cameras in Pakistan

    Shahid, M.A.; Mumtaz-ul-Haq

    1988-01-01

    The evaluation of the performance of both instrument and the physician are important in any quality assurance programme in nuclear medicine imaging. The IAEA launched a similar program in 1984 under its Regional Cooperation Agreement program in South Asian Countries. The first part of the study consisted of the evaluation of imaging equipment by imaging IAEA-WHO Simulated Anatomic Liver Phantom (SALP) and its interpretation by the physician. From Pakistan, 8 gamma cameras from 7 laboratories were used for the study and 16 physician interpreted in the SALP images. This paper reports the results of SALP images from Pakistan and shows the efficacy of 80 to 100% as regards the quality of image obtained and the interpretation done by the physicians. (author)

  6. Standardization of test conditions for gamma camera performance measurement

    Jordan, K.

    1980-01-01

    The actual way of measuring gamma camera performance is to use point sources or flood sources in air, often in combination with bar phantoms. This method mostly brings best performance parameters for cameras but it has nothing in common with the use of a camera in clinical practice. Particular in the case of low energy emitters, like Tc-99m, the influence of scattered radiation over the performance of cameras is very high. Therefore it is important to have test conditions of radionuclide imaging devices, that will approach as best as practicable the measuring conditions in clinical applications. It is therefore a good news that the International Electrochemical Commission IEC has prepared a draft 'Characteristics and test conditions of radionuclide imaging devices' which is now submitted to the national committees for formal approval under the Six Months' Rule. Some essential points of this document are discussed in the paper. (orig.) [de

  7. Monte Carlo simulation for dual head gamma camera

    Osman, Yousif Bashir Soliman

    2015-12-01

    Monte Carlo (MC) simulation technique was used widely in medical physics applications. In nuclear medicine MC was used to design new medical imaging devices such as positron emission tomography (PET), gamma camera and single photon emission computed tomography (SPECT). Also it can be used to study the factors affecting image quality and internal dosimetry, Gate is on of monte Carlo code that has a number of advantages for simulation of SPECT and PET. There is a limit accessibilities in machines which are used in clinics because of the work load of machines. This makes it hard to evaluate some factors effecting machine performance which must be evaluated routinely. Also because of difficulties of carrying out scientific research and training of students, MC model can be optimum solution for the problem. The aim of this study was to use gate monte Carlo code to model Nucline spirit, medico dual head gamma camera hosted in radiation and isotopes center of Khartoum which is equipped with low energy general purpose LEGP collimators. This was used model to evaluate spatial resolution and sensitivity which is important factor affecting image quality and to demonstrate the validity of gate by comparing experimental results with simulation results on spatial resolution. The gate model of Nuclide spirit, medico dual head gamma camera was developed by applying manufacturer specifications. Then simulation was run. In evaluation of spatial resolution the FWHM was calculated from image profile of line source of Tc 99m gammas emitter of energy 140 KeV at different distances from modeled camera head at 5,10,15,20,22,27,32,37 cm and for these distances the spatial resolution was founded to be 5.76, 7.73, 10.7, 13.8, 14.01,16.91, 19.75 and 21.9 mm, respectively. These results showed a decrement of spatial resolution with increase of the distance between object (line source) and collimator in linear manner. FWHM calculated at 10 cm was compared with experimental results. The

  8. High purity materials as targets for radioisotope production: Needs ...

    Unknown

    lity of high purity target materials, natural or enriched, are crucial for any successful radioisotope pro- gramme. Selection ... and blockages detection in buried pipelines are rendered ..... from reputed international suppliers with analysis report.

  9. High-Purity Glasses Based on Arsenic Chalcogenides

    2001-06-01

    Chemical interaction of chalcogenides and some impurities (CS 2, TeO2 ) with the quartz glass at high temperature leads to the thin layers formation...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO1 1523 TITLE: High-Purity Glasses Based on Arsenic Chalcogenides...Materials Vol. 3, No. 2, June 2001, p. 341 - 349 HIGH-PURITY GLASSES BASED ON ARSENIC CHALCOGENIDES M. F. Churbanov, I. V. Scripachev, G. E. Snopatin, V. S

  10. Gamma camera correction system and method for using the same

    Inbar, D.; Gafni, G.; Grimberg, E.; Bialick, K.; Koren, J.

    1986-01-01

    A gamma camera is described which consists of: (a) a detector head that includes photodetectors for producing output signals in response to radiation stimuli which are emitted by a radiation field and which interact with the detector head and produce an event; (b) signal processing circuitry responsive to the output signals of the photodetectors for producing a sum signal that is a measure of the total energy of the event; (c) an energy discriminator having a relatively wide window for comparison with the sum signal; (d) the signal processing circuitry including coordinate computation circuitry for operating on the output signals, and calculating an X,Y coordinate of an event when the sum signal lies within the window of the energy discriminator; (e) an energy correction table containing spatially dependent energy windows for producing a validation signal if the total energy of an event lies within the window associated with the X,Y coordinates of the event; (f) the signal processing circuitry including a dislocation correction table containing spatially dependent correction factors for converting the X,Y coordinates of an event to relocated coordinates in accordance with correction factors determined by the X,Y coordinates; (g) a digital memory for storing a map of the radiation field; and (h) means for recording an event at its relocated coordinates in the memory if the energy correction table produces a validation signal

  11. Two dimensional spatial distortion correction algorithm for scintillation GAMMA cameras

    Chaney, R.; Gray, E.; Jih, F.; King, S.E.; Lim, C.B.

    1985-01-01

    Spatial distortion in an Anger gamma camera originates fundamentally from the discrete nature of scintillation light sampling with an array of PMT's. Historically digital distortion correction started with the method based on the distortion measurement by using 1-D slit pattern and the subsequent on-line bi-linear approximation with 64 x 64 look-up tables for X and Y. However, the X, Y distortions are inherently two-dimensional in nature, and thus the validity of this 1-D calibration method becomes questionable with the increasing distortion amplitude in association with the effort to get better spatial and energy resolutions. The authors have developed a new accurate 2-D correction algorithm. This method involves the steps of; data collection from 2-D orthogonal hole pattern, 2-D distortion vector measurement, 2-D Lagrangian polynomial interpolation, and transformation to X, Y ADC frame. The impact of numerical precision used in correction and the accuracy of bilinear approximation with varying look-up table size have been carefully examined through computer simulation by using measured single PMT light response function together with Anger positioning logic. Also the accuracy level of different order Lagrangian polynomial interpolations for correction table expansion from hole centroids were investigated. Detailed algorithm and computer simulation are presented along with camera test results

  12. Standardization of the intrinsic uniformity control of the gamma cameras

    Solsona Harster, Lluis; Llopis Gonzalez, David; Pavia Segura, Javier

    2001-01-01

    Objective: To verify the Intrinsic Uniformity (Iu) results using different acquisition parameters in the weekly gamma camera Quality Control (Qc). Material And Methods: We made 4 experiments using Tc99 sources and modifying the orientation, distance, activity an volume parameters of a source in ten detectors with I Na photomultipliers applying the following acquisition conditions: 4000 Kc, the source 2 m far from the geometrical centre of the detectors, 0.1 ml into 1 ml syringe, and 150 Tc99m ?Ci. Results: We found better results when the distance between detector/source is getting longer, but the better point we found between 1,5 and 2 m. We also found necessary the collimator position was parallel respect to the geometrical centre field of view, because a little deviation of only two degrees can offer a bad result between +0.5%. We study the dose that we should use, and the results show us that better results are not in the highest or smallest values of activity into the source. In volume parameters, we can see that if we use a source highest than 1 ml we obtained better results. Conclusion: Following our results in the variation of IU values as for as the distance, rotation detector/source, dose and source activity, we recommend to perform this QC applying NEMA rules in same conditions every week and using the different parameters of our study to obtain better IU (Au)

  13. Preliminary study for pixel identification on a modular gamma camera

    Soluri, A., E-mail: soluri@isib.cnr.it; Atzeni, G.; Ucci, A.; Cusanno, F.; Massari, R.

    2014-02-01

    Our group has recently investigated and produced new scintigraphic prototypes based on advanced scintillation structure. The aim of this study is to demonstrate the use of scintillation matrices with size equal to the overall area of the Position Sensitive Photomultiplier Tube (PSPMT), to design a modular gamma camera and study the solution of the dead area problems optimizing the overall pixel identification. In this paper we investigate the response of different combinations with crystals integrated within tungsten structure, coupled with H8500, R8900-C12 and R11265-M64 Hamamatsu PSPMTs. Several scintillation matrices, whose dimensions match to the physical area of the PSPMT, have been analysed so that we have also studied limits of detection for the elements of the matrix in the critical zones of the PSPMT, i.e. corners and borders. In order to enhance the detectability of scintillation elements we improved the light collection by depositing metallic layers or treating the tungsten structure with different coating materials, and shaping the external elements of the scintillation matrices. The results have shown good energy resolution and the proposed method can be applied in medical imaging for obtaining high efficiency scintillation devices.

  14. Assessment of gamma camera performance at some Sudanese hospitals

    Ibrahim, Nour El huda Ibrahim Ali

    2016-05-01

    The study aims to investigate the performance quality of the gamma cameras used in three public hospitals in Sudan. It is widely recognized that the attainment of high standards of efficiency and reliability in the practice of nuclear medicine, as in other specialties based on advanced technology, requires an appropriate quality assurance program. In this study we have focused on four of the main tests in order to assess the performance of the three units in question, such as uniformity, resolution/ linearity, center of rotation, photopeak. The values were within the acceptable range (according to the adopted protocols). Overall performance of the units was acceptable. Although all the results were within the acceptable range, some of them were at border, thus an action of preventive maintenance should be considered. It is noticed that a minor to negligible co-operation exists between the centers experts and /or equipment. The establishment of an external and internal auditing program is recommended. More co-operation between the centers should be considered.(Author)

  15. Ectomography - a tomographic method for gamma camera imaging

    Dale, S.; Edholm, P.E.; Hellstroem, L.G.; Larsson, S.

    1985-01-01

    In computerised gamma camera imaging the projections are readily obtained in digital form, and the number of picture elements may be relatively few. This condition makes emission techniques suitable for ectomography - a tomographic technique for directly visualising arbitrary sections of the human body. The camera rotates around the patient to acquire different projections in a way similar to SPECT. This method differs from SPECT, however, in that the camera is placed at an angle to the rotational axis, and receives two-dimensional, rather than one-dimensional, projections. Images of body sections are reconstructed by digital filtration and combination of the acquired projections. The main advantages of ectomography - a high and uniform resolution, a low and uniform attenuation and a high signal-to-noise ratio - are obtained when imaging sections close and parallel to a body surface. The filtration eliminates signals representing details outside the section and gives the section a certain thickness. Ectomographic transverse images of a line source and of a human brain have been reconstructed. Details within the sections are correctly visualised and details outside are effectively eliminated. For comparison, the same sections have been imaged with SPECT. (author)

  16. Evaluation of tomographic ISOCAM Park II gamma camera parameters using Monte Carlo method

    Oramas Polo, Ivón

    2015-01-01

    In this paper the evaluation of tomographic ISOCAM Park II gamma camera parameters was performed using the Monte Carlo code SIMIND. The parameters uniformity, resolution and contrast were evaluated by Jaszczak phantom simulation. In addition the qualitative assessment of the center of rotation was performed. The results of the simulation are compared and evaluated against the specifications of the manufacturer of the gamma camera and taking into account the National Protocol for Quality Control of Nuclear Medicine Instruments of the Cuban Medical Equipment Control Center. A computational Jaszczak phantom model with three different distributions of activity was obtained. They can be used to perform studies with gamma cameras. (author)

  17. Manufacturing P-N junctions in germanium bodies

    Hall, R.N.

    1980-01-01

    A method of producing p-n junctions in Ge so as to facilitate their use as radiation detectors involves forming a body of high purity p-type germanium, diffusing lithium deep into the body, in the absence of electrolytic processes, to form a junction between n-type and p-type germanium greater than 1 mm depth. (UK)

  18. Design of gamma camera data acquisition system based on PCI9810

    Zhao Yuanyuan; Zhao Shujun; Liu Yang

    2004-01-01

    This paper describe the design of gamma camera's data acquisition system, which is based on PCI9810 data acquisition card of ADLink Technology Inc. The main function of PCI9810 and the program of data acquisition system are described. (authors)

  19. Improving the spatial resolution of the multiple multiwire proportional chamber gamma camera

    Bateman, J.E.; Connolly, J.F.

    1978-03-01

    Results are presented showing how the spatial resolution of the multiple multiwire proportional chamber (MMPC) gamma camera may be improved. Under the best conditions 1.6 mm bars can be resolved. (author)

  20. Production of high purity granular metals: cadmium, zinc, lead

    Shcherban A. P.

    2017-04-01

    Full Text Available Cadmium, zinc and lead are constituent components of many semiconductor compounds. The obtained high purity distillates and ingots are large-size elements, which is not always convenient to use, and thus require additional grinding, which does not always allow maintaining the purity of the original materials. For the growth of semiconductor and scintillation single crystals it is advisable to use "friable" granular high-purity distillates, which can be processed without the risk of contamination. For example, the European low-background experiment LUCIFER required more than 20 kg of high-purity granulated zinc, which was agreed to be supplied by NSC KIPT. This task was then extended to cadmium and lead. Motivated by these tasks, the authors of this paper propose complex processes of deep refining of cadmium, zinc and lead by vacuum distillation. A device producing granules has been developed. The process of granulation of high-purity metals is explored. The purity of produced granules for cadmium and zinc is >99,9999, and >99,9995% for lead granules. To prevent oxidation of metal granules during exposition to air, chemical methods of surface passivation were used. Organic solvent based on dimethylformamide used as a coolant improves the resistance of granules to atmospheric corrosion during the granulation of high purity Cd, Zn and Pb.

  1. Effect of phosphorus on hot ductility of high purity iron

    Abiko, K.; Liu, C.M.; Ichikawa, M..; Suenaga, H.; Tanino, M.

    1995-01-01

    Tensile tests on high purity Fe-P alloys with 0, 0.05 and 0.1 mass%P were carried out at temperatures between 300 K and 1073 K to clarify the intrinsic effect of phosphorus on the mechanical properties of iron at elevated temperatures. Microstructures of as-quenched, interrupted and ruptured specimens were observed. Experimental results show that the addition of phosphorus causes a remarkable increase in proof stress of high purity iron at 300 K, but the increase in proof stress by phosphorus decreases with increasing test temperature. The strengthening effect of phosphorus reduces to zero at 1073 K. High purity iron and Fe-P alloys rupture at almost 100% reduction in area at the whole test temperatures. However, Fe-P alloys show much larger elongation at test temperatures above 773 K than high purity iron. The increased elongation of high purity iron by addition of phosphorus was shown to be related to the effect of phosphorus on dynamic recovery and recrystallization of iron as its intrinsic effect. (orig.)

  2. Dual photon absorptiometry for bone mineral measurements using a gamma camera

    Valkema, R.; Prpic, H.; Blokland, J.A.K.; Camps, J.A.J.; Papapoulos, S.E.; Bijvoet, O.L.M.; Pauwels, E.K.J.

    1994-01-01

    A gamma camera was equipped with a special collimator and arm assembly for bone mineral measurements with dual photon absorptiometry (DPA). The system was evaluated in vitro and in vivo and compared both with a rectilinear DPA and a dual energy X-ray (DEXA) system. All 3 systems showed a linear response in measurements of 4 vials, containing different amounts of hydroxyapatite. Phantom measurements with the gamma camera system showed a precision of 1.6% to 2.8%. Results obtained in 8 healthy volunteers with rectilinear and gamma camera systems were well correlated (R 2 = 0.78). With the photon beam directed from posterior to anterior, the separation of vertebrae was easy with the gamma camera system. We conclude that bone mineral measurements can be made with a gamma camera for assessment of fracture risk and in the decision process whether a patient needs treatment or not. For follow-up, the precision of DPA with a gamma camera is inadequate. (orig.)

  3. High-purity aluminium creep under high hydrostatic pressure

    Zajtsev, V.I.; Lyafer, E.I.; Tokij, V.V.

    1977-01-01

    The effect of the hydrostatic pressure on the rate of steady-state creep of high-purity aluminium was investigated. It is shown that the hydrostatic pressure inhibits the creep. The activation volume of the creep is independent of the direction in the range of (4.7-6.2) kg/mm 2 and of the pressure in the range of (1-7.8000) atm. It is concluded that self-diffusion does not control the creep of high-purity aluminium at room temperature in the investigated stress and pressure range

  4. Development of high purity niobium material for superconducting cavities

    Umezawa, Hiroaki; Takeuchi, Koichi; Sakita, Kohei; Suzuki, Takafusa; Saito, Kenji; Noguchi, Shuichi.

    1993-01-01

    For the superconducting niobium cavities, issues of thermal quench and field emission have to be solved to achieve a high field gradient (>25MV/m) for TESLA (TeV Energy Superconducting Linear Accelerator). In order to overcome the quench, upgrading of thermal conductivity of niobium material at the low temperature is very important. On the reduction of the field emission not only dust particles but also defect, impurity and inhomogeneity should be considered. Therefore development of high purity niobium material is very important to solve these issues. This paper describes the our latest R and D for high purity niobium material. (author)

  5. 131I activity quantification of gamma camera planar images

    Barquero, Raquel; Garcia, Hugo P.; Incio, Monica G.; Minguez, Pablo; Cardenas, Alexander; Martínez, Daniel; Lassmann, Michael

    2017-02-01

    A procedure to estimate the activity in target tissues in patients during the therapeutic administration of 131I radiopharmaceutical treatment for thyroid conditions (hyperthyroidism and differentiated thyroid cancer) using a gamma camera (GC) with a high energy (HE) collimator, is proposed. Planar images are acquired for lesions of different sizes r, and at different distances d, in two HE GC systems. Defining a region of interest (ROI) on the image of size r, total counts n g are measured. Sensitivity S (cps MBq-1) in each acquisition is estimated as the product of the geometric G and the intrinsic efficiency η 0. The mean fluence of 364 keV photons arriving at the ROI per disintegration G, is calculated with the MCNPX code, simulating the entire GC and the HE collimator. Intrinsic efficiency η 0 is estimated from a calibration measurement of a plane reference source of 131I in air. Values of G and S for two GC systems—Philips Skylight and Siemens e-cam—are calculated. The total range of possible sensitivity values in thyroidal imaging in the e-cam and skylight GC measure from 7 cps MBq-1 to 35 cps MBq-1, and from 6 cps MBq-1 to 29 cps MBq-1, respectively. These sensitivity values have been verified with the SIMIND code, with good agreement between them. The results have been validated with experimental measurements in air, and in a medium with scatter and attenuation. The counts in the ROI can be produced by direct, scatter and penetration photons. The fluence value for direct photons is constant for any r and d values, but scatter and penetration photons show different values related to specific r and d values, resulting in the large sensitivity differences found. The sensitivity in thyroidal GC planar imaging is strongly dependent on uptake size, and distance from the GC. An individual value for the acquisition sensitivity of each lesion can significantly alleviate the level of uncertainty in the measurement of thyroid uptake activity for each patient.

  6. Initial clinical experience with dedicated ultra fast solid state cardiac gamma camera

    Aland, Nusrat; Lele, V.

    2010-01-01

    Full text: To analyze the imaging and diagnostic performance of new dedicated ultra fast solid state detector gamma camera and compare it with standard dual detector gamma camera in myocardial perfusion imaging. Material and Methods: In total 900 patients underwent myocardial perfusion imaging between 1st February 2010 and 29th August 2010 either stress/rest or rest/stress protocol. There was no age or gender bias (there were 630 males and 270 females). 5 and 15 mCi of 99m Tc - Tetrofosmin/MIBI was injected for 1st and 2nd part of the study respectively. Waiting period after injection was 20 min for regular stress and 40 min for pharmacological stress and 40 min after rest injection. Acquisition was performed on solid state detector gamma camera for a duration of 5 min and 3 min for 1st and 2nd part respectively. Interpretation of myocardial perfusion was done and QGS/QPS protocol was used for EF analysis. Out of these, 20 random patients underwent back to back myocardial perfusion SPECT imaging on standard dual detector gamma camera on same day. There was no age or gender bias (there were 9 males, 11 females). Acquisition time was 20 min for each part of the study. Interpretation was done using Autocard and EF analyses with 4 DM SPECT. Images obtained were then compared with those of solid state detector gamma camera. Result: Good quality and high count myocardial perfusion images were obtained with lesser amount of tracer activity on solid state detector gamma camera. Obese patients also showed good quality images with less tracer activity. As compared to conventional dual detector gamma camera images were brighter and showed better contrast with solid state gamma camera. Right ventricular imaging was better seen. Analyses of diastolic dysfunction was possible with 16 frame gated studies with solid state gamma camera. Shorter acquisition time with comfortable position reduced possibility of patient motion. All cardiac views were obtained with no movement of the

  7. A study on the performance evaluation of small gamma camera collimators using detective quantun efficiency

    Jeon, Ho Sang

    2008-02-01

    The anger-type gamma camera and novel marker compound using Tc-99m were firstly introduced in 1963. The gamma camera systems have being improved and applied to various fields, for example, medical, industrial, and environmental fields. Gamma camera is mainly composed of collimator, detector, and signal processor. And the radiative source is namely the imaging object. The collimator is essential component of gamma camera system because the imaging performance of system is mainly dependent on the collimator. The performance evaluation of collimators can be done by using evaluating factors. In this study, the novel factors for gamma camera evaluation are suggested. The established evaluating factors by NEMA are FWHM, sensitivity, and uniformity. They have some limitations in spite of their usefulness. Firstly, performance evaluation by those factors give insensitive and indirect results only. Secondly, the evaluation of noise property is ambiguous. Thirdly, there is no synthetic evaluation of system performance. Simulation with Monte Carlo code and experiment with a small camera camera were simultaenuously performed to verify novel evaluating factors. For the evaluation of spatial resolution, MTF was applied instead of FWHM. The MTF values presents excellent linear relationship with FWHM values. The NNPS was applied instead of uniformity and sensitivity for the evaluation of noise fluctuation. The NNPS values also presents linear relationship with sensitivity and unifomity. Moreover, these novel factors give quantities as the function of spatial frequencies. Finally, the DQE values were given by calculations with MTF, NNPS, and input SNR. DQE effectively presents the synthetic evaluation of gamma camera performance. It is the conclusion that MTF, NNPS, and DQE can be novel evaluating factors for gamma camera systems and the new factor for synthetic evaluation is derived

  8. High purity liquid phase epitaxial gallium arsenide nuclear radiation detector

    Alexiev, D.; Butcher, K.S.A.

    1991-11-01

    Surface barrier radiation detector made from high purity liquid phase epitaxial gallium arsenide wafers have been operated as X- and γ-ray detectors at various operating temperatures. Low energy isotopes are resolved including 241 Am at 40 deg C. and the higher gamma energies of 235 U at -80 deg C. 15 refs., 1 tab., 6 figs

  9. Pressure-assisted sintering of high purity barium titanate

    van den Cruijsem, S.; Varst, van der P.G.T.; With, de G.; Bortzmeyer, D.; Boussuge, M.; Chartier, Th.; Hausonne, J.M.; Mocellin, A.; Rousset, A.; Thevenot, F.

    1997-01-01

    The dielectric behaviour of High Purity Barium titanate (HPB) ceramics is strongly dependent on the grain size and porosity. For applications, control of grain size and porosity is required. Pressure-assisted sintering techniques at relatively low temperatures meet these requirements. In this study,

  10. Isolation of high purity americium metal via distillation

    Squires, Leah N.; King, James A.; Fielding, Randall S.; Lessing, Paul

    2018-03-01

    Pure americium metal is a crucial component for the fabrication of transmutation fuels. Unfortunately, americium in pure metal form is not available; however, a number of mixed metals and mixed oxides that include americium are available. In this manuscript a method is described to obtain high purity americium metal from a mixture of americium and neptunium metals with lead impurity via distillation.

  11. Analysis of the dead layer of a detector of germanium with code ultrapure Monte Carlo SWORD-GEANT; Analisis del dead layer de un detector de germanio ultrapuro con el codigo de Monte Carlo SWORDS-GEANT

    Gallardo, S.; Querol, A.; Ortiz, J.; Rodenas, J.; Verdu, G.

    2014-07-01

    In this paper the use of Monte Carlo code SWORD-GEANT is proposed to simulate an ultra pure germanium detector High Purity Germanium detector (HPGe) detector ORTEC specifically GMX40P4, coaxial geometry. (Author)

  12. Development of a high sensitivity pinhole type gamma camera using semiconductors for low dose rate fields

    Ueno, Yuichiro; Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi; Fujishima, Yasutake; Yoshida, Akira; Umegaki, Kikuo

    2018-06-01

    We developed a pinhole type gamma camera, using a compact detector module of a pixelated CdTe semiconductor, which has suitable sensitivity and quantitative accuracy for low dose rate fields. In order to improve the sensitivity of the pinhole type semiconductor gamma camera, we adopted three methods: a signal processing method to set the discriminating level lower, a high sensitivity pinhole collimator and a smoothing image filter that improves the efficiency of the source identification. We tested basic performances of the developed gamma camera and carefully examined effects of the three methods. From the sensitivity test, we found that the effective sensitivity was about 21 times higher than that of the gamma camera for high dose rate fields which we had previously developed. We confirmed that the gamma camera had sufficient sensitivity and high quantitative accuracy; for example, a weak hot spot (0.9 μSv/h) around a tree root could be detected within 45 min in a low dose rate field test, and errors of measured dose rates with point sources were less than 7% in a dose rate accuracy test.

  13. Fabrication of a phantom and its application for checking gamma camera performance

    Yesmin, S; Ahmad, G. U.; Afroz, S.; Hossain, S.; Rashid, H.

    2004-01-01

    The primary aim of the present work is to fabricate a total performance phantom, which could be used for checking the performance characteristics of gamma camera. The phantom was locally fabricated at machine shop of Bangladesh University of Engineering and Technology (BUET) and used for checking the performance characteristics of gamma camera LF-61 of Centre for Nuclear Medicine and Ultrasound, Dhaka. With 10 mCi of Tc-99m, imaging of the phantom acquired with a reasonable counts. The image was inspected physically for evaluation of the camera performances. The visual inspection of the phantom image revealed that the performance characteristics like: spatial resolution, linearity, uniformity and lesion detection capability of the gamma camera could clearly be evaluated with reasonable acceptance level. This phantom is expected to be useful for checking performance characteristics of SPECT system as well. (author)

  14. Gamma camera image acquisition, display, and processing with the personal microcomputer

    Lear, J.L.; Pratt, J.P.; Roberts, D.R.; Johnson, T.; Feyerabend, A.

    1990-01-01

    The authors evaluated the potential of a microcomputer for direct acquisition, display, and processing of gamma camera images. Boards for analog-to-digital conversion and image zooming were designed, constructed, and interfaced to the Macintosh II (Apple Computer, Cupertino, Calif). Software was written for processing of single, gated, and time series images. The system was connected to gamma cameras, and its performance was compared with that of dedicated nuclear medicine computers. Data could be acquired from gamma cameras at rates exceeding 200,000 counts per second, with spatial resolution exceeding intrinsic camera resolution. Clinical analysis could be rapidly performed. This system performed better than most dedicated nuclear medicine computers with respect to speed of data acquisition and spatial resolution of images while maintaining full compatibility with the standard image display, hard-copy, and networking formats. It could replace such dedicated systems in the near future as software is refined

  15. Gamma camera computer system quality control for conventional and tomographic use

    Laird, E.E.; Allan, W.; Williams, E.D.

    1983-01-01

    The proposition that some of the proposed measurements of gamma camera performance parameters for routine quality control are redundant and that only the uniformity requires daily monitoring was examined. To test this proposition, measurements of gamma camera performance were carried out under normal operating conditions and also with the introduction of faults (offset window, offset PM tube). Results for the uniform flood field are presented for non-uniformity, intrinsic spatial resolution, linearity and relative system sensitivity. The response to introduced faults revealed that while the non-uniformity response pattern of the gamma camera was clearly affected, both measurements and qualitative indications of the other performance parameters did not necessarily show any deterioration. (U.K.)

  16. Utilization of a gamma camera in research of the concentration in marine products

    Nakamura, Ryoichi

    1981-01-01

    A gamma camera was used for the study of the metabolism of micro elements in marine products. Hexagrammos otakii (rock trout) was put under anesthesia with MS-222. By cutting partly the abdomen, the internal organs were exposed. 1 - 2 mCi of technetium-99m was injected into the bulbus arteriosus. From immediately after the injection, photographs were taken consecutively, one picture every 0.5 second for 30 seconds, to a total of 60 pictures. Since the gamma camera has been developed solely for human beings, there is some inconvenience when it is applied to marine products. The advantages of using a gamma camera are the observation on the behavior of substances in a body while a marine product is alive, and the grasping of the variation in substance behavior at extremely brief intervals. The disadvantages are the low resolution of about 5 mm - 7 mm, and the difficulty in differentiating overlapping organs. (J.P.N.)

  17. Recovery of high-purity hydrogen from COG

    Tsukiyama, Y

    1982-01-01

    A general account of the latest trends in the recovery of high-purity hydrogen from coke oven gas (COG), the article being based on both Japanese and overseas literature: 1) Deep-freeze separation: impurities are liquefied and removed. This method make use of the fact that hydrogen is hard to liquefy. 2) The PSA method: high-purity hydrogen is recovered by the adsorption of other constituents at high pressures. This technique makes use of the fact that the adsorption capacity of an adsorbent varies with the partial pressure of the substances being adsorbed. 3) Membrane separation: a permeation separation method that uses a functional polymer separation membrane, and that depends on the fact that hydrogen has a low molecular weight in comparison with the other constituents. (19 refs.) (In Japanese)

  18. Demands made on high-purity copper for special purposes

    Roettges, D.

    1977-01-01

    The properties (electrical resistivity, residual impurities) of high-purity copper produced on a technical scale are reported as well as its practical applications. The paper discusses a high-oxygen copper (SV) with low residual resistivity at low temperatures and an oxygen-free (hydrogen-stable) copper (BE electronic) with low gas content. The SV quality has been specially developed for use as stabilizer in superconductors while the BE quality is used in high and ultrahigh vacuum. (GSC) [de

  19. 18F half-life measurement using a high-purity germanium detector

    Han, Jubong; Lee, K.B.; Park, T.S.; Lee, J.M.; Oh, P.J.; Lee, S.H.; Kang, Y.S.; Ahn, J.K.

    2012-01-01

    The half-life of 18 F has been measured using HPGe detectors with a 137 Cs reference source. The counting ratio of 511 keV γ-rays from 18 F to 622 keV γ-rays from 137 Cs was fitted for the half-life with a weighted least-square method. Uncertainties due to the systematic effects arising from the measurement of a high activity 18 F source were studied in detail. The half-life of 18 F was found to be (109.72±0.19) min. The result is in a good agreement with the recommended value of (109.728±0.019) min evaluated at the Laborotaire National Henri Becquerel (LNHB). - Highlights: ► The 18 F half-life was measured with a reference source and without it using HPGe detectors. ► We found the systematic effect ‘activity dynamic range effect’ by monitoring the counts of the reference source. ► This activity dynamic range effect was corrected by using the reference source method. ► The 18 F half-life using the reference source method was in a good agreement with the recommended value of LNHB.

  20. Source term estimation based on in-situ gamma spectrometry using a high purity germanium detector

    Pauly, J.; Rojas-Palma, C.; Sohier, A.

    1997-06-01

    An alternative method to reconstruct the source term of a nuclear accident is proposed. The technique discussed here involves the use of in-situ gamma spectrometry. The validation of the applied methodology has been possible through the monitoring of routine releases of Ar-41 originating at a Belgian site from an air cooled graphite research reactor. This technique provides a quick nuclide specific decomposition of the source term and therefore will be have an enormous potential if implemented in nuclear emergency preparedness and radiological assessments of nuclear accidents during the early phase

  1. Gamma ray spectrum of Am 241 in a backscattering geometry using a high purity germanium detector

    Chong Chon Sing; Ibrahim Salih Elyaseery; Ahmad Shukri Mustapa Kamal; Abdul Aziz Tajuddin

    1997-01-01

    In back scattering geometry using an annular Am-241 source and a HPGE detector has been set up to study both the coherent and incoherent scattering of photon emissions of Am-241 from medium-Z and high-Z elements. Besides the coherent and incoherent scattered peaks of the emissions from the source, the gamma ray spectrum from the different target elements obtained using a microcomputer based multichannel analyser showed the presence of several other peaks. These peaks have been identified to arise from the fluorescence of the targets, the fluorescence of the shielding material Pb, and also as fluorescence sum peaks and X-ray escape peaks of the detector material Ge. The spectra are presented for three target elements viz. Mo, Zn and W

  2. Surface passivation of high purity granular metals: zinc, cadmium, lead

    Pirozhenko L. A.

    2017-10-01

    Full Text Available For the high purity metals (99.9999%, such as zinc, cadmium, and lead, which are widely used as initial components in growing semiconductor and scintillation crystals (CdTe, CdZnTe, ZnSe, (Cd, Zn, Pb WO4, (Cd, Zn, Pb MoO4 et al., it is very important to ensure reliable protection of the surface from oxidation and adsorption of impurities from the atmosphere. The specific features of surface passivation of high purity cadmium, lead and zinc are not sufficiently studied and require specific methodologies for further studies. The use of organic solutions in the schemes of chemical passivation of the investigated metals avoids hydrolysis of the obtained protective films. The use of organic solvents with pure cation and anion composition as the washing liquid prevents chemisorption of ions present in the conventionally used distilled water. This keeps the original purity of the granular metals. Novel compositions of etchants and etching scheme providing simultaneous polishing and passivation of high purity granular Zn, Cd and Pb are developed. Chemical passivation allows storing metals in the normal atmospheric conditions for more than half a year for Zn and Cd and up to 30 days for Pb without changing the state of the surface. The use of the glycerol-DMF solution in the processes for obtaining Pb granules provides self-passivation of metal surfaces and eliminates the additional chemical processing while maintaining the quality of corrosion protection.

  3. A technique for the absolute measurement of activity using a gamma camera and computer

    Fleming, J.S.

    1979-01-01

    The quantity of activity of an isotope in an organ is of interest in gamma camera studies. There are problems in correcting the regional gamma camera counts for varying absorption in body tissue, particularly for thick organs. A description is given of a general method, based on anterior, posterior and lateral views. The method has been applied to liver 99 Tcsup(m) sulphur colloid imaging. Phantom measurements showed that the smallest error to be expected was 3.2%. In practice errors would be 5 to 10%, although lower errors would be associated with estimates of liver/spleen ratios. (U.K.)

  4. Geant4 simulation of a 3D high resolution gamma camera

    Akhdar, H.; Kezzar, K.; Aksouh, F.; Assemi, N.; AlGhamdi, S.; AlGarawi, M.; Gerl, J.

    2015-01-01

    The aim of this work is to develop a 3D gamma camera with high position resolution and sensitivity relying on both distance/absorption and Compton scattering techniques and without using any passive collimation. The proposed gamma camera is simulated in order to predict its performance using the full benefit of Geant4 features that allow the construction of the needed geometry of the detectors, have full control of the incident gamma particles and study the response of the detector in order to test the suggested geometries. Three different geometries are simulated and each configuration is tested with three different scintillation materials (LaBr3, LYSO and CeBr3)

  5. Bullet scintigraphy: can gamma camera be used for depleted uranium accident measurements?

    Spaic, R.; Markovic, S.; Pavlovic, S.; Radic, Z.; Pavlovic, R.; Ajdinovic, B.; Baskot, B.; Djurovic, B.

    2002-01-01

    The aim of this study was to see could gamma cameras be used for measurement of internal contamination with depleted uranium. Radioactive waste depleted uranium, which is by-product from the production of enriched fuel for nuclear rectors and weapons now, is used for manufacture bullets, which are used in Iraq, Republic of Srpska and Yugoslavia. In this paper is measured minimum detectable activity (MDA) of gamma cameras for depleted uranium, iodine and technetium. For detection of the depleted uranium are used low energy X-rays, energy of 100 keV with 20% windows width. About 40% of gamma emissions of the depleted uranium are in these limits. Measured MDA activities 50-100 Bq for depleted uranium, iodine and technetium are about then times more then same for WBC (5 Bq). Gamma cameras can be used for relatively measurement of depleted uranium activity, what can be used for absorbed dose estimation. Detection of low level internal contamination with depleted uranium can be done with gamma cameras. (authors)

  6. Defective organification of iodine in an infant demonstrated with 123J and gamma camera

    Goebel, R.; Leb, G.; Sulzer, M.; Graz Univ.

    1979-01-01

    A defective organification of iodine is demonstrated in a two year old male infant. The availability and a relatively simple radiation detector and storage system (gamma camera and 1600 word memory) gives a reasonable low radiation dose, allows correction for extrathyroid neck activity and obviates problems of collimation. (orig.) [de

  7. Impact of intense x-ray pulses on a NaI(Tl)-based gamma camera

    Koppert, Wilco J C; van der Velden, Sandra; Steenbergen, J H Leo; de Jong, Hugo W A M

    2018-01-01

    INTRODUCTION: In SPECT/CT systems X-ray and -ray imaging is performed sequentially. Simultaneous acquisition may have advantages, for instance in interventional settings. However, this may expose a gamma camera to relatively high X-ray doses and deteriorate its functioning. We studied the NaI(Tl)

  8. Gastric emptying of liquid meals: validation of the gamma camera technique

    Lawaetz, Otto; Dige-Petersen, Harriet

    1989-05-01

    To assess the extent of errors and to provide correction factors for gamma camera gastric emptying studies of liquid meals labelled with radionuclides (/sup 99/Tc/sup m/ or /sup 113/In/sup m/), phantom studies were performed with different gastric emptying procedures, gamma cameras and data handling systems. To validate the overall accuracy of the method, 24 combined aspiration and gamma camera gastric emptying studies were carried out in three normal volunteers. Gastric meal volume was underestimated due to scattered radiation from the stomach. The underestimation was 7-20% varying with the size of the gastric region of interest (ROI), the energy of the nuclide and the fraction of meal in the stomach. The overestimation, due to scattered radiation from the gut, was negligible (1-3%) for any of the procedures. The gamma camera technique eliminated much of the error due to variations of stomach geometry and produced accurate quantitative gastric emptying data comparable to those obtained by evacuation (P > 0.10), when the entire field maximum 1-min count achieved within the first 20 min of a study was taken as representing the original volume of the meal ingested, and when corrections for area related errors due to scattered radiation from the stomach were performed. (author).

  9. Gamma camera with an original system of scintigraphic image printing incorporated

    Roux, G.

    A new gamma camera has been developed, using Anger's Principle to localise the scintillations and incorporating the latest improvements which give a standard of efficiency at present competitive for this kind of apparatus. In the general design of the system special care was devoted to its ease of employment and above all to the production of high-quality scintigraphic images, the recording of images obtained from the gamma camera posing a problem to which a solution is proposed. This consists in storing all the constituent data of an image in a cell matrix of format similar to the scope of the object, the superficial information density of the image being represented by the cell contents. When the examination is finished a special printer supplies a 35x43 cm 2 document in colour on paper, or in black and white on radiological film, at 2:1 or 1:1 magnifications. The laws of contrast representation by the colours or shades of grey are chosen a posteriori according to the organ examined. Documents of the same quality as those so far supplied by a rectilinear scintigraph are then obtained with the gamma camera, which offers its own advantages in addition. The first images acquired in vivo with the whole system, gamma camera plus printer, are presented [fr

  10. Characteristics of a single photon emission tomography system with a wide field gamma camera

    Mathonnat, F.; Soussaline, F.; Todd-Pokropek, A.E.; Kellershohn, C.

    1979-01-01

    This text summarizes a work study describing the imagery possibilities of a single photon emission tomography system composed of a conventional wide field gamma camera, connected to a computer. The encouraging results achieved on the various phantoms studied suggest a significant development of this technique in clinical work in Nuclear Medicine Departments [fr

  11. A study on the optimization of optical guide of gamma camera detector

    Chung, Yong Hyun; Cho, Gyu Seong; Kim, Ho Kyung; Lee, Wan No; Kim, Young Soo

    2000-01-01

    An optical guide, which is a light guide located between NaI(Tl) scintillation-crystal and array of photo-multiplier tubes (PMTs) in the gamma camera detector system, is an essential component to deliver the spatial information recorded in scintillator to the PMTs. Without the optical guide, the spatial information within the range of a single PMT could not be obtained. For the design of the optimal optical guide, it is necessary to characterize its properties, especially sensitivity and spatial resolution of detector. In this study, the thickness and the refractive index of optical guide, which affect not only on the sensitivity but also on the spatial resolution of gamma-camera detector, were investigated by using Monte Carlo simulation. A 12'x12'x3/8' NaI(Tl) and 23 PMTs with each 5' diameter were considered as a gamma-camera detector components. Interactions of optical photons in the scintillator and the optical guide were simulated using a commercial code DETECT97, and the spatial resolution, mainly interfered by the intrinsic inward distortion within the PMT, was investigated using our own ANGER program, which was developed to calculate positions of incident photons in the gamma camera. From the simulation results, it was found that an optical guide with 1.6 of refractive index and 10 mm of thickness give maximum sensitivity and minimum spatial distortion, respectively

  12. Process for the production of high purity deuterium

    Arrathoon, R.

    1977-01-01

    A process for the electrolysis of heavy water which results in the production of high purity deuterium without periodic replenishment of the electrolyte with additional deuterated compounds is defined. Electrolysis is effected through the use of an inexpensive cation-action permselective membrane which is essentially a solid polymer electrolyte and which is capable of automatically separating the evolved deuterium and oxygen gas. This cation-active permselective membrane does not introduce any intrinsic impurities or tritium contamination in the generated deuterium gas, does not require periodic revitalization with deuterated compounds or other chemical compounds, and is characterized by an unusually high electrical efficiency

  13. Shock loading influence on mechanical behavior of high purity iron

    Buy, Francois; Voltz, Christophe

    2004-01-01

    This paper proposes the analysis of shock wave effects for high purity iron. The method developed is based on the characterization of the mechanical behavior of as received and shocked material. Shock effect is generated through plate impact tests performed in the range of 4 GPa to 39 GPa on a single stage light gas gun or a powder gun. Therefore, as-received and impacted materials are characterized. A formalism proposed by J.R.Klepaczko and based on physical relations has been adopted to describe stress strain curves

  14. Neutron activation analysis of high-purity zinc

    Khodzhamberdyeva, A.A.; Usmanova, M.M.; Gil'bert, Eh.N.; Ivanov, I.M.; Yankovskaya, T.A.; Kholyavko, E.P.

    1987-01-01

    The methods of neutron activation analysis of high-purity zinc with preliminary separation of the zinc base using extraction by trialkylbenzylammonium rhodanide in carbon tetrachloride from 0.5-2.0 M nitric acid solutions is developed. Only rhenium is quantitatively extracted together with zinc. Gold, iridium and molybdenum are extracted to 50-60%, and selenium - to 20%. The Na, K, La, Cr, Sc, Co, Cs, Rb, Fe, Zr, Sn, Te, As, Cd, Hf, W, Sb, Sm impurities remain in the aqueous phase. The methods permits to determine the impurities above with detection limits from 1x10 -6 to 4x10 -11 g

  15. The ion-exchange obtaining of high purity samarium oxide

    Brzyska, W.; Soltysiak, I.; Cygan, J.

    1987-01-01

    The use of lactic acid - EDTA mixture as an eluent for the obtaining of high purity samarium oxide was studied. The studies were carried out at room temperature on cation exchange resin Wofatit KPS X 8. The best results were obtained for lactic acid (0,26 mol/dm 3 ) - EDTA (0,013 mol/dm 3 ) mixture at pH 3,3. As the result of 57% samarium concentrate elution with column load 1:3 and flow rate 0,4 cm/min, over 99% pure samarium oxide with 73% yield has been obtained. The yield of spectrally pure Sm 2 O 3 exceeded 45%. (author)

  16. Release characteristics of tritium from high-purity lithium oxide

    O'Kula, K.R.; Vogelsang, W.F.

    1985-01-01

    Rates of tritium release from neutronirradiated lithium oxide were determined from isothermal release experiments. High-purity, monocrystalline lithium oxide was purged ex-reactor with helium and helium-hydrogen gas streams. Overall release was found to be controlled by solid-phase diffusion, and was predominantly in the form of condensible species. The result of an independent concentration profile analysis at 923 K was in agreement with the gas release diffusion coefficient. Sweeping the Li 2 O with hydrogen-containing gas was found to enhance tritium removal during the early stage of each run

  17. Amplitude dependent damping in single crystalline high purity molybdenum

    Zelada-Lambri, G.I; Lambri, O.A; Garcia, J.A; Lomer, J.N

    2004-01-01

    Amplitude dependent damping measurements were performed on high purity single crystalline molybdenum at several different constant temperatures between room temperature and 1273K. The employed samples were single crystals with the orientation, having a residual resistivity ratio of about 8000. Previously to the amplitude dependent damping tests, the samples were subjected to different thermomechanical histories. Amplitude dependent damping effects appear only during the first heating run in temperature where the samples have the thermomechanical state of the deformation process at room temperature. In the subsequent run-ups in temperature, i.e, after subsequent annealings, amplitude dependent damping effects were not detected (au)

  18. A protocol for the calibration of gamma cameras to estimate internal contamination in emergency situations

    Dantas, B.M.; Lucena, E.A.; Dantas, A.L.A.; Araujo, F.; Melo, D.; Rebelo, A.M.O.; Teran, M.; Paolino, A.; Hermida, J.C.; Rojo, A.M.; Puerta, J.A.; Morales, J.; Bejerano, G.M.L.; Alfaro, M.; Ruiz, M.A.; Videla, R.; Pinones, O.; Gonzalez, S.; Navarro, T.; Cruz-Suarez, R.

    2007-01-01

    The concern about accidents involving radioactive materials has led to the search of alternative methods to quickly identify and quantify radionuclides in workers and in the population. One of the options to face up an eventual demand for mass monitoring of internal contamination is the use of a nuclear medicine diagnostic equipment known as gamma camera, a device used to scan patients who have been administered specific amounts of radioactive materials for medical purposes. Although the gamma camera is used for image diagnosis, it can be calibrated with anthropomorphic phantoms or point sources for the quantification of radionuclide activities in the human body. This work presents a protocol for the calibration of gamma cameras for such application. In order to evaluate the suitability of this type of equipment, a gamma camera available in a public hospital located in Rio de Janeiro was calibrated for the in vivo measurement of 131 I. The calibration includes the determination of detection efficiencies and minimum detectable activities for each radionuclide. The results show that the gamma camera presents enough sensitivity to detect activity levels corresponding to effective doses below 1 mSv. The protocol is the basis to establish a network of Nuclear Medicine Centres, located in public hospitals in eight countries of Latin America (Argentina, Brazil, Colombia, Cuba, Chile, Mexico, Peru and Uruguay) and in Spain that could be requested to collaborate in remediation actions in the event of an accident involving incorporation of radioactive materials. This protocol is one of the most significant outputs of the IAEA-ARCAL Project (RLA/9/049-LXXVIII) aimed to the Harmonization of Internal Dosimetry Procedures. (authors)

  19. A protocol for the calibration of gamma cameras to estimate internal contamination in emergency situations

    Dantas, B.M.; Lucena, E.A.; Dantas, A.L.A.; Araujo, F.; Melo, D. [Instituto de Radioprotecao e Dosimetria, CNEN, Av. Salvador Allende s/n, Rio de Janeiro (Brazil); Rebelo, A.M.O. [University Hospital, Nuclear Medicine Center, Rio de Janeiro (Brazil); Teran, M.; Paolino, A. [Facultad de Quimica, Montevideo (Uruguay); Hermida, J.C. [Hospital de Clinicas, Facultad de Medicina, Montevideo (Uruguay); Rojo, A.M. [Autoridad Regulatoria Nuclear, Buenos Aires (Argentina); Puerta, J.A.; Morales, J. [Universidad Nacional de Colombia, Medellin (Colombia); Bejerano, G.M.L. [Centro de Proteccion e Higiene de las Radiaciones, Ciudad de la Habana (Cuba); Alfaro, M.; Ruiz, M.A. [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac (Mexico); Videla, R.; Pinones, O. [Comision Chilena de Energia Nuclear, Santiago (Chile); Gonzalez, S. [Instituto Peruano de Energia Nuclear, Lima (Peru); Navarro, T. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain); Cruz-Suarez, R. [International Atomic Energy Agency, Vienna (Austria)

    2007-07-01

    The concern about accidents involving radioactive materials has led to the search of alternative methods to quickly identify and quantify radionuclides in workers and in the population. One of the options to face up an eventual demand for mass monitoring of internal contamination is the use of a nuclear medicine diagnostic equipment known as gamma camera, a device used to scan patients who have been administered specific amounts of radioactive materials for medical purposes. Although the gamma camera is used for image diagnosis, it can be calibrated with anthropomorphic phantoms or point sources for the quantification of radionuclide activities in the human body. This work presents a protocol for the calibration of gamma cameras for such application. In order to evaluate the suitability of this type of equipment, a gamma camera available in a public hospital located in Rio de Janeiro was calibrated for the in vivo measurement of {sup 131}I. The calibration includes the determination of detection efficiencies and minimum detectable activities for each radionuclide. The results show that the gamma camera presents enough sensitivity to detect activity levels corresponding to effective doses below 1 mSv. The protocol is the basis to establish a network of Nuclear Medicine Centres, located in public hospitals in eight countries of Latin America (Argentina, Brazil, Colombia, Cuba, Chile, Mexico, Peru and Uruguay) and in Spain that could be requested to collaborate in remediation actions in the event of an accident involving incorporation of radioactive materials. This protocol is one of the most significant outputs of the IAEA-ARCAL Project (RLA/9/049-LXXVIII) aimed to the Harmonization of Internal Dosimetry Procedures. (authors)

  20. Development of high purity large forgings for nuclear power plants

    Tanaka, Yasuhiko; Sato, Ikuo

    2011-01-01

    The recent increase in the size of energy plants has been supported by the development of manufacturing technology for high purity large forgings for the key components of the plant. To assure the reliability and performance of the large forgings, refining technology to make high purity steels, casting technology for gigantic ingots, forging technology to homogenize the material and consolidate porosity are essential, together with the required heat treatment and machining technologies. To meet these needs, the double degassing method to reduce impurities, multi-pouring methods to cast the gigantic ingots, vacuum carbon deoxidization, the warm forging process and related technologies have been developed and further improved. Furthermore, melting facilities including vacuum induction melting and electro slag re-melting furnaces have been installed. By using these technologies and equipment, large forgings have been manufactured and shipped to customers. These technologies have also been applied to the manufacture of austenitic steel vessel components of the fast breeder reactors and components for fusion experiments.

  1. High purity in steels as a criterion for materials development

    Jacobi, H.

    1995-01-01

    This summarizing report discusses the materials and application prospects for higher purity in steels, which will make possible further advances in materials behaviour and workability. Improvements in purity and homogeneity permit in particular more rational production of thin foils and wire, one-piece shaping of complicated bodywork components and the drawing, wall-ironing and flanging of two-piece beverage cans. Welded designs in plant and mechanical engineering can be fabricated with less effort and less weight. Difficult component geometries and shaping processes can be more easily mastered. Steels with optimized fracture toughness can be exposed to more extreme loads at even lower temperatures: applications worthy of mention include offshore engineering and large-diameter linepipes for use in arctic regions and at great underwater depths. Liquefied-gas transport vessels can be made more resistant to brittle rupture. The bending fatigue strength and service-life of valve-spring and rolling-bearing steels can be significantly increased. High-purity surfaces on piston rods and cylinders guarantee reliability in hydraulic systems, and high-purity calendering rolls permit defect-free embossing of paper surfaces. (orig.)

  2. Development of high purity large forgings for nuclear power plants

    Tanaka, Yasuhiko; Sato, Ikuo

    2011-10-01

    The recent increase in the size of energy plants has been supported by the development of manufacturing technology for high purity large forgings for the key components of the plant. To assure the reliability and performance of the large forgings, refining technology to make high purity steels, casting technology for gigantic ingots, forging technology to homogenize the material and consolidate porosity are essential, together with the required heat treatment and machining technologies. To meet these needs, the double degassing method to reduce impurities, multi-pouring methods to cast the gigantic ingots, vacuum carbon deoxidization, the warm forging process and related technologies have been developed and further improved. Furthermore, melting facilities including vacuum induction melting and electro slag re-melting furnaces have been installed. By using these technologies and equipment, large forgings have been manufactured and shipped to customers. These technologies have also been applied to the manufacture of austenitic steel vessel components of the fast breeder reactors and components for fusion experiments.

  3. The Research about Preparation of High Purity Hexachlorodisilane

    Wan, Ye; Zhao, Xiong; Yan, Dazhou; Zhao, Yu; Guo, Shuhu; Wang, Lei; Yang, Dian

    2017-12-01

    This article demonstrated a technology for producing high purity hexachlorodisilane what is one raw material of Semiconductor industry, which using the method of combination adsorption with rectification, whose material was from polysilicon residues of polysilicon company. This technology could remove most high boiling points chloro-silicane impurities and metal impurities effectively. The purity of Si2Cl6 produced by this technology can be up to 99.9%, the content of metal impurities can be low at 4ppb, which can meet the requirement of industy using completely. The technology extends the routes of Si2Cl6 in localization, having the advantages of simple process, continuous operation, and large capacity and so on.

  4. Deuterium permeation and diffusion in high-purity beryllium

    Abramov, E.; Riehm, M.P.; Thompson, D.A.; Smeltzer, W.W.

    1990-01-01

    The permeation rate of deuterium through high-purity beryllium membranes was measured using the gas-driven permeation technique. The time-dependent and the steady-state deuterium flux data were analyzed and the effective diffusivities of the samples were determined. Using multilayer permeation theory the effects of surface oxide were eliminated and the diffusion coefficients of the bulk beryllium determined. The diffusion parameters obtained for the extra-grade beryllium samples (99.8%) are D 0 =6.7x10 -9 m 2 /s and E D =28.4 kJ/mol. For the high-grade beryllium samples (99%) the parameters are D 0 =8.0x10 -9 m 2 /s and E D =35.1 kJ/mol. (orig.)

  5. Deuterium permeation and diffusion in high purity beryllium

    Abramov, E.

    1990-05-01

    The permeation rate of deuterium through high-purity beryllium membranes was measured using the gas-driven permeation technique. The time-dependent and the steady-state deuterium flux data were analyzed and the effective diffusivities of the samples were determined. A multilayer permeation theory was used in order to eliminate the surface oxide effects and the diffusion coefficients of the bulk beryllium were determined. The diffusion parameters obtained for the extra-grade beryllium samples (99.8%) are D 0 = 6.7 x 10 -9 [m 2 /s] and E D = 28.4 [KJ/mol]; and for the high-grade beryllium samples (99%) the parameters are D 0 = 8.0 x 10 -9 [m 2 /s] and E D = 35.1 [KJ/mol

  6. Thermal and electrical conductivities of high purity tantalum

    Archer, S.L.

    1978-01-01

    The electrical resistivity and thermal conductivity of three high purity tantalum samples have been measured as functions of temperature over a temperature range of 5K to 65K. Sample purities ranged up to a resistivity ratio of 1714. The highest purity sample had a residual resistivity of .76 x 10 -10 OMEGA-m. The intrinsic resistivity varied as T 3 . 9 from 10K to 31K. The thermal conductivity of the purest sample had a maximum of 840 W/mK at 9.8K. The intrinsic thermal resistivity varied as T 2 . 4 from 10K to 35K. At low temperatures electrons were scattered primarily by impurities and by phonons with both interband and intraband transitions observed. The electrical and thermal resistivity is departed from Matthiessen's rule at low temperatures

  7. Preparation of high purity yttrium single crystals by electrotransport

    Volkov, V.T.; Nikiforova, T.V.; Ionov, A.M.; Pustovit, A.N.; Sikharulidse, G.G.

    1981-01-01

    The possibility of obtaining yttrium crystals of high purity by the method of solid state electrotransport (SSE) was investigated in the present work. The behaviour of low contents of iron, aluminium, silicon, tantalum, copper, silver and vanadium as metallic impurities was studied using mass spectrometry. It is shown that all the impurities investigated, except copper, migrate to the anode. During electrotransfer a purification with respect to these impurities by a factor of 4 - 6 is obtained. It is proposed that the diffusion coefficients of the metallic impurities investigated are anomalously high and that the behaviour of the impurities during SSE in adapters necessitates further investigation. By using a three-stage process with intermediate removal of the anode end yttrium single crystals with a resistance ratio rho 293 /rhosub(4.2)=570 were produced. (Auth.)

  8. High purity zirconium obtainment through the iodine compounds transport method

    Bolcich, J.C.; Zuzek, E.; Dutrus, S.M.; Corso, H.L.

    1987-01-01

    This paper describes the experimental method and the equipment designed, constructed and actually applied for the high purity zirconium obtainment from a zirconium sponge of the nuclear type. The mechanism of purification is based on the impure metal attack with gaseous iodine (at 200 deg C) to obtain zirconium tetra iodine as main product which is then transformed into a pure zirconium base (at 1000-1300 deg C), precipitating the metallic zirconium and releasing the gaseous iodine. From the first experiences carried out, pure zirconium has been obtained from an initial filament of 0.5 mm of diameter as well as wires up to 2.5 mm of diameter. This work presents the results from the studies and analysis made to characterize the material obtained. Finally, the refining methods to which the zirconium produced may be submitted so as to optimize the final purity are discussed. (Author)

  9. Precipitation of hydrides in high purity niobium after different treatments

    Barkov, F.; Romanenko, A.; Trenikhina, Y.; Grassellino, A.

    2013-01-01

    Precipitation of lossy non-superconducting niobium hydrides represents a known problem for high purity niobium in superconducting applications. Using cryogenic optical and laser confocal scanning microscopy we have directly observed surface precipitation and evolution of niobium hydrides in samples after different treatments used for superconducting RF cavities for particle acceleration. Precipitation is shown to occur throughout the sample volume, and the growth of hydrides is well described by the fast diffusion-controlled process in which almost all hydrogen is precipitated at $T=140$~K within $\\sim30$~min. 120$^{\\circ}$C baking and mechanical deformation are found to affect hydride precipitation through their influence on the number of nucleation and trapping centers.

  10. Investigation of sulphides in iron alloys of high purity

    Wyjadlowski, T.

    1973-01-01

    This research thesis reports the study of the morphology and composition of sulphides in iron alloys with respect to metal composition and to the nature of impurities. In order to understand the specific action of each addition on inclusion morphology, this work has started with high-purity alloys (binary alloys and then ternary alloys). The author studied whether solubility variations would entail either intergranular or intragranular or hybrid iron sulphide precipitation. He examined whether sulphide morphology is depending on thermal treatment, and whether equilibrium precipitates were different in terms of morphology and composition at high and room temperature. He studied the influence of addition elements on sulphide morphology and composition, an important issue as some elements may reduce brittleness. These elements are classified in terms of affinity with sulphur

  11. High purity neodymium acetate from mixed rare earth carbonates

    Queiroz, Carlos A. da Silva; Rocha, Soraya M. Rizzo da; Vasconcellos, Mari E. de; Lobo, Raquel M.; Seneda, Jose A.; Pedreira, Walter dos R.

    2011-01-01

    A simple and economical chemical process for obtaining high purity neodymium acetate is discussed. The raw material in the form rare earth carbonate is produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography technique with a strong cationic resin, proper to water treatment, and without the use of retention ions was used for the fractionating of the rare earth elements (REE). In this way, it was possible to obtain 99.9% pure Nd 2 O 3 in yields greater than or equal 80%, with the elution of the REE using ammonium salt of ethylenediaminetetraacetic acid (EDTA) solution in pH controlled. The complex of EDTA-neodymium was transformed into neodymium oxide, which was subsequently dissolved in acetic acid to obtain the neodymium acetates. Molecular absorption spectrophotometry was used to monitor the neodymium content during the process and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the neodymium acetates. The typical neodymium acetates obtained contain the followings contaminants in μg g -1 : Sc(5.1); Y (0.9); La (1.0); Ce (6.1); Pr (34,4); Sm (12.8); Eu (1.1); Gd (15.4); Tb (29.3); Dy (5.2), Ho(7.4); Er (14.6); Tm (0.3); Yb (2.5); Lu (1.0). The high purity neodymium acetates obtained from this procedure have been applied, replacing the imported product, in research and development area on rare earth catalysts. (author)

  12. NEMA NU-1 2007 based and independent quality control software for gamma cameras and SPECT

    Vickery, A; Joergensen, T; De Nijs, R

    2011-01-01

    A thorough quality assurance of gamma and SPECT cameras requires a careful handling of the measured quality control (QC) data. Most gamma camera manufacturers provide the users with camera specific QC Software. This QC software is indeed a useful tool for the following of day-to-day performance of a single camera. However, when it comes to objective performance comparison of different gamma cameras and a deeper understanding of the calculated numbers, the use of camera specific QC software without access to the source code is rather avoided. Calculations and definitions might differ, and manufacturer independent standardized results are preferred. Based upon the NEMA Standards Publication NU 1-2007, we have developed a suite of easy-to-use data handling software for processing acquired QC data providing the user with instructive images and text files with the results.

  13. Multiwire proportional gamma camera for imaging /sup 99/Tcsup(m) radionuclide distributions

    Bateman, J E; Connolly, J F [Science Research Council, Chilton (UK). Rutherford Lab.

    1978-05-01

    A gamma camera made of multiple multiwire proportional chambers with thin converter foils has been evaluated for clinical application. Results are presented from a small prototype (10 cm x 10 cm) showing good imaging of /sup 99/Tcsup(m) radionuclide distributions and confirming the predictions of the theory regarding quantum efficiency and spatial resolution. The technique is especially aimed at creating a gamma camera with an active area > approximately 3 1m/sup 2/, a quantum efficiency of 15% and a spatial resolution approximately 3 mm, whole body scanning and tomographic applications. The results generated by the current prototype indicate that the above requirements can be met using relatively cheap mass production techniques from the electronics industry. This apparatus is covered by patent application number 26595/77.

  14. A multiwire proportional gamma camera for imaging 99Tcsup(m) radionuclide distributions

    Bateman, J.E.; Connolly, J.F.

    1978-01-01

    A gamma camera made of multiple multiwire proportional chambers with thin converter foils has been evaluated for clinical application. Results are presented from a small prototype (10 cm x 10 cm) showing good imaging of 99 Tcsup(m) radionuclide distributions and confirming the predictions of the theory regarding quantum efficiency and spatial resolution. The technique is especially aimed at creating a gamma camera with an active area > approximately 3 1m 2 , a quantum efficiency of 15% and a spatial resolution approximately 3 mm, whole body scanning and tomographic applications. The results generated by the current prototype indicate that the above requirements can be met using relatively cheap mass production techniques from the electronics industry. This apparatus is covered by patent application number 26595/77. (author)

  15. Development and evaluation of a portable CZT coded aperture gamma-camera

    Montemont, G.; Monnet, O.; Stanchina, S.; Maingault, L.; Verger, L. [CEA, LETI, Minatec Campus, Univ. Grenoble Alpes, 38054 Grenoble, (France); Carrel, F.; Lemaire, H.; Schoepff, V. [CEA, LIST, 91191 Gif-sur-Yvette, (France); Ferrand, G.; Lalleman, A.-S. [CEA, DAM, DIF, 91297 Arpajon, (France)

    2015-07-01

    We present the design and the evaluation of a CdZnTe (CZT) based gamma camera using a coded aperture mask. This camera, based on a 8 cm{sup 3} detection module, is small enough to be portable and battery-powered (4 kg weight and 4 W power dissipation). As the detector has spectral capabilities, the gamma camera allows isotope identification and colored imaging, by affecting one color channel to each identified isotope. As all data processing is done at real time, the user can directly observe the outcome of an acquisition and can immediately react to what he sees. We first present the architecture of the system, how the detector works, and its performances. After, we focus on the imaging technique used and its strengths and limitations. Finally, results concerning sensitivity, spatial resolution, field of view and multi-isotope imaging are shown and discussed. (authors)

  16. Development and evaluation of a portable CZT coded aperture gamma-camera

    Montemont, G.; Monnet, O.; Stanchina, S.; Maingault, L.; Verger, L.; Carrel, F.; Lemaire, H.; Schoepff, V.; Ferrand, G.; Lalleman, A.-S.

    2015-01-01

    We present the design and the evaluation of a CdZnTe (CZT) based gamma camera using a coded aperture mask. This camera, based on a 8 cm 3 detection module, is small enough to be portable and battery-powered (4 kg weight and 4 W power dissipation). As the detector has spectral capabilities, the gamma camera allows isotope identification and colored imaging, by affecting one color channel to each identified isotope. As all data processing is done at real time, the user can directly observe the outcome of an acquisition and can immediately react to what he sees. We first present the architecture of the system, how the detector works, and its performances. After, we focus on the imaging technique used and its strengths and limitations. Finally, results concerning sensitivity, spatial resolution, field of view and multi-isotope imaging are shown and discussed. (authors)

  17. A gamma camera method for quantitation of split renal function in children followed for vesicoureteric reflux

    Tamminen, T.E.; Riihimaeki, E.J.; Taehti, E.E.; Helsinki Univ. Central Hospital

    1978-01-01

    A method for quantitative estimation of split renal function using a computerized gamma camera system is described. 42 children and adolescents with existing or preexisting vesicouretric reflux and recurrent urinary tract infection were investigated. Total renal clearance of DTPA was calculated with a disapperarance curve derived from the largest extrarenal area in the field of view of a gamma camera with diverging collimator. Split renal function was estimated with the slopes of second phase renograms. The plasma disaapearance clearance of DTPA, calculated using one compartement model with two late blood samples, gave similar resusults with the clearance estimated from the body disappearance curves. The proportional planimetric renal parenchymal areas had good correlation with the split clearance estimated from renogram slopes. The method offers data on renal function and urinary tract dynamics which is very valuable in the follow-up of children with recurrent urinary tract infection and vesicoureteric reflux. (orig.) [de

  18. Development of gamma camera display phantom for quality control in developing countries

    Todd-Pokropek, A.

    1981-08-01

    A special phantom suitable for the routine evaluation of ''end-to-end'' gamma camera system performance, that is, system performance from input to output, is described. The design finally adopted, called the ''strip-wedge phantom'' and consisting of an array of copper or aluminium wedges of various thicknesses, permits the evaluation of contrast along one axis and resolution along the other. It is proposed that on acceptance testing of a gamma camera system a series of progressively degraded images should be obtained from the best possible with the system to very poor. An ''action threshold'' should then be defined such that image quality below this threshold would warrant such action as calling in the service engineer. Daily routine images should then be examined with reference to this threshold. Experience with the phantom is summarized

  19. From whole-body counting to imaging: The computer aided collimation gamma camera project (CACAO)

    Jeanguillaume, C.; Begot, S.; Quartuccio, M.; Douiri, A.; Ballongue, P

    2000-07-01

    Whole-body counting is the method of choice for in vivo detection of contamination. To extend this well established method, the possible advantages of imaging radiocontaminants are examined. The use of the CACAO project is then studied. A comparison of simulated reconstructed images obtained by the CACAO project and by a conventional gamma camera used in nuclear medicine follows. Imaging a radionuclide contaminant with a geometrical sensitivity of 10{sup -2} seems possible in the near future. (author)

  20. From whole-body counting to imaging: The computer aided collimation gamma camera project (CACAO)

    Jeanguillaume, C.; Begot, S.; Quartuccio, M.; Douiri, A.; Ballongue, P.

    2000-01-01

    Whole-body counting is the method of choice for in vivo detection of contamination. To extend this well established method, the possible advantages of imaging radiocontaminants are examined. The use of the CACAO project is then studied. A comparison of simulated reconstructed images obtained by the CACAO project and by a conventional gamma camera used in nuclear medicine follows. Imaging a radionuclide contaminant with a geometrical sensitivity of 10 -2 seems possible in the near future. (author)

  1. SU-E-E-06: Teaching About the Gamma Camera and Ultrasound Imaging

    Lowe, M; Spiro, A [Loyola University Maryland, Baltimore, Maryland (United States); Vogel, R [Iowa Doppler Products, Iowa City, Iowa (United States); Donaldson, N; Gosselin, C [Rockhurst University, Kansas City, MO (United States)

    2015-06-15

    Purpose: Instructional modules on applications of physics in medicine are being developed. The target audience consists of students who have had an introductory undergraduate physics course. This presentation will concentrate on an active learning approach to teach the principles of the gamma camera. There will also be a description of an apparatus to teach ultrasound imaging. Methods: Since a real gamma camera is not feasible in the undergraduate classroom, we have developed two types of optical apparatus that teach the main principles. To understand the collimator, LEDS mimic gamma emitters in the body, and the photons pass through an array of tubes. The distance, spacing, diameter, and length of the tubes can be varied to understand the effect upon the resolution of the image. To determine the positions of the gamma emitters, a second apparatus uses a movable green laser, fluorescent plastic in lieu of the scintillation crystal, acrylic rods that mimic the PMTs, and a photodetector to measure the intensity. The position of the laser is calculated with a centroid algorithm.To teach the principles of ultrasound imaging, we are using the sound head and pulser box of an educational product, variable gain amplifier, rotation table, digital oscilloscope, Matlab software, and phantoms. Results: Gamma camera curriculum materials have been implemented in the classroom at Loyola in 2014 and 2015. Written work shows good knowledge retention and a more complete understanding of the material. Preliminary ultrasound imaging materials were run in 2015. Conclusion: Active learning methods add another dimension to descriptions in textbooks and are effective in keeping the students engaged during class time. The teaching apparatus for the gamma camera and ultrasound imaging can be expanded to include more cases, and could potentially improve students’ understanding of artifacts and distortions in the images.

  2. SU-E-E-06: Teaching About the Gamma Camera and Ultrasound Imaging

    Lowe, M; Spiro, A; Vogel, R; Donaldson, N; Gosselin, C

    2015-01-01

    Purpose: Instructional modules on applications of physics in medicine are being developed. The target audience consists of students who have had an introductory undergraduate physics course. This presentation will concentrate on an active learning approach to teach the principles of the gamma camera. There will also be a description of an apparatus to teach ultrasound imaging. Methods: Since a real gamma camera is not feasible in the undergraduate classroom, we have developed two types of optical apparatus that teach the main principles. To understand the collimator, LEDS mimic gamma emitters in the body, and the photons pass through an array of tubes. The distance, spacing, diameter, and length of the tubes can be varied to understand the effect upon the resolution of the image. To determine the positions of the gamma emitters, a second apparatus uses a movable green laser, fluorescent plastic in lieu of the scintillation crystal, acrylic rods that mimic the PMTs, and a photodetector to measure the intensity. The position of the laser is calculated with a centroid algorithm.To teach the principles of ultrasound imaging, we are using the sound head and pulser box of an educational product, variable gain amplifier, rotation table, digital oscilloscope, Matlab software, and phantoms. Results: Gamma camera curriculum materials have been implemented in the classroom at Loyola in 2014 and 2015. Written work shows good knowledge retention and a more complete understanding of the material. Preliminary ultrasound imaging materials were run in 2015. Conclusion: Active learning methods add another dimension to descriptions in textbooks and are effective in keeping the students engaged during class time. The teaching apparatus for the gamma camera and ultrasound imaging can be expanded to include more cases, and could potentially improve students’ understanding of artifacts and distortions in the images

  3. An alternate way for image documentation in gamma camera processing units

    Schneider, P.

    1980-01-01

    For documentation of images and curves generated by a gamma camera processing system a film exposure tool from a CT system was linked to the video monitor by use of a resistance bridge. The machine has a stock capacity of 100 plane films. For advantage there is no need for an interface, the complete information on the monitor is transferred to the plane film and compared to software controlled data output on printer or plotter the device is tremendously time saving. (orig.) [de

  4. The role of the gamma camera in the study of gastric function

    Esser, J.D.; Mannell, A.; Hinder, R.A.

    1984-01-01

    With the gamma camera food labelled with radioactive tracers can be visualized as it enters and leaves the stomach. Radiopharmaceuticals such as technetium-99m di-isopropyl iminodiacetic acid simulate the bile pathway and can be used to demonstrate duodenogastric reflux. Duodenogastric reflux and gastric emptying of solid or liquid meals can be quantitated when the gamma camera is linked to a microprocessor. The test meal used at the Johannesburg and Hillbrow Hospitals consists of a 99 (sup m)Tc-labelled chicken liver weighing 30 g mixed with 70 g cooked ground beef. These studies are valuable for investigating symptomatic postgastrectomy patients and patients who have neurogenic or metabolic diseases which result in abnormal gastric function. The efficacy of drugs given to relieve these symptoms can also be assessed. In this paper we discuss the nuclear medicine techniques used to study gastric function. Examples are given of abnormalities which may not be diagnosed on gastroscopy or barium meal examination but which can be clearly identified by gamma camera techniques

  5. Use of gamma camera for measurement of the internal contamination with depleted uranium

    Spaic, R.; Markovic, S.; Pavlovic, S.; Pavlovic, R.; Ajdinovic, B.; Baskot, B.; Djurovic, B.

    2000-01-01

    Depleted uranium from radioactive wastes is used for manufacturing bullets used in Iraq, Republic of Serbia and Yugoslavia. These bullets are extremely dense and capable of penetrating heavily armored vehicles. Their medical importance lies in the fact that the bullets contain seventy percent depleted uranium which creates aerosolized particles less than five microns in diameter, small enough to be inhaled, after spontaneous bullet burn at impact. Nuclear medicine scientists must be aware of this and be prepared to measure internal contamination of persons exposed to this radioactive material. Whole body counters (WBC) represent appropriate equipment for this purpose but their availability in developing countries is not sufficient. Gamma camera is an alternative. The minimum detectable activity (MDA) of depleted uranium, iodine and technetium for gamma cameras was measured in this paper. Low energy X-ray 100 KeV with 20% windows are used for the depleted uranium detection. About 40% gamma emissions from depleted uranium fall within these limits. The activities measured (50-100 Bq) are about ten times higher then on WBC (5 Bq). This does not limit the use of gamma cameras for measurement of lung or whole body internal contamination with depleted uranium. (author)

  6. A didactic experiment showing the Compton scattering by means of a clinical gamma camera.

    Amato, Ernesto; Auditore, Lucrezia; Campennì, Alfredo; Minutoli, Fabio; Cucinotta, Mariapaola; Sindoni, Alessandro; Baldari, Sergio

    2017-06-01

    We describe a didactic approach aimed to explain the effect of Compton scattering in nuclear medicine imaging, exploiting the comparison of a didactic experiment with a gamma camera with the outcomes from a Monte Carlo simulation of the same experimental apparatus. We employed a 99m Tc source emitting 140.5keV photons, collimated in the upper direction through two pinholes, shielded by 6mm of lead. An aluminium cylinder was placed on the source at 50mm of distance. The energy of the scattered photons was measured on the spectra acquired by the gamma camera. We observed that the gamma ray energy measured at each step of rotation gradually decreased from the characteristic energy of 140.5keV at 0° to 102.5keV at 120°. A comparison between the obtained data and the expected results from the Compton formula and from the Monte Carlo simulation revealed a full agreement within the experimental error (relative errors between -0.56% and 1.19%), given by the energy resolution of the gamma camera. Also the electron rest mass has been evaluated satisfactorily. The experiment was found useful in explaining nuclear medicine residents the phenomenology of the Compton scattering and its importance in the nuclear medicine imaging, and it can be profitably proposed during the training of medical physics residents as well. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  7. Slit-Slat Collimator Equipped Gamma Camera for Whole-Mouse SPECT-CT Imaging

    Cao, Liji; Peter, Jörg

    2012-06-01

    A slit-slat collimator is developed for a gamma camera intended for small-animal imaging (mice). The tungsten housing of a roof-shaped collimator forms a slit opening, and the slats are made of lead foils separated by sparse polyurethane material. Alignment of the collimator with the camera's pixelated crystal is performed by adjusting a micrometer screw while monitoring a Co-57 point source for maximum signal intensity. For SPECT, the collimator forms a cylindrical field-of-view enabling whole mouse imaging with transaxial magnification and constant on-axis sensitivity over the entire axial direction. As the gamma camera is part of a multimodal imaging system incorporating also x-ray CT, five parameters corresponding to the geometric displacements of the collimator as well as to the mechanical co-alignment between the gamma camera and the CT subsystem are estimated by means of bimodal calibration sources. To illustrate the performance of the slit-slat collimator and to compare its performance to a single pinhole collimator, a Derenzo phantom study is performed. Transaxial resolution along the entire long axis is comparable to a pinhole collimator of same pinhole diameter. Axial resolution of the slit-slat collimator is comparable to that of a parallel beam collimator. Additionally, data from an in-vivo mouse study are presented.

  8. Preliminary Experience with Small Animal SPECT Imaging on Clinical Gamma Cameras

    P. Aguiar

    2014-01-01

    Full Text Available The traditional lack of techniques suitable for in vivo imaging has induced a great interest in molecular imaging for preclinical research. Nevertheless, its use spreads slowly due to the difficulties in justifying the high cost of the current dedicated preclinical scanners. An alternative for lowering the costs is to repurpose old clinical gamma cameras to be used for preclinical imaging. In this paper we assess the performance of a portable device, that is, working coupled to a single-head clinical gamma camera, and we present our preliminary experience in several small animal applications. Our findings, based on phantom experiments and animal studies, provided an image quality, in terms of contrast-noise trade-off, comparable to dedicated preclinical pinhole-based scanners. We feel that our portable device offers an opportunity for recycling the widespread availability of clinical gamma cameras in nuclear medicine departments to be used in small animal SPECT imaging and we hope that it can contribute to spreading the use of preclinical imaging within institutions on tight budgets.

  9. Active noise canceling system for mechanically cooled germanium radiation detectors

    Nelson, Karl Einar; Burks, Morgan T

    2014-04-22

    A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

  10. High purity samarium oxide from mixed rare earth carbonates

    Queiroz, Carlos A. da S.; Seneda, Jose A.; Vasconcellos, Mari E. de; Pedreira Filho, Walter dos R.

    2013-01-01

    A simple and economical chemical process for the production of highly pure samarium oxides is discussed. The raw material, which was used in the form of rare earth carbonates was produced industrially from the chemical treatment of Brazilian monazite. Ion exchange chromatography was performed using a strong cationic resin that is typically employed in water treatment processes to fractionate rare earth elements (REE) without the use of retention ions. Under these conditions, 99.9% pure Sm 2 O 3 was eluted using the ammonium salt of ethylenediaminetetraacetic acid (EDTA) at a controlled pH. The EDTA-samarium complex was separated from EDTA and then precipitated as oxalate and fired to samarium oxide. Molecular absorption spectrophotometry was used to monitor the samarium content during the proposed process, and sector field inductively coupled plasma mass spectrometry was used to certify the purity of the samarium oxide. Typical samarium oxide obtained from the proposed procedure contained the following contaminants in micrograms per gram: Sc (20.90); Y (11.80); La (8.4); Ce (4.3); Pr (2.5); Nd (5.1); Eu (94); Gd (114); Tb (3.6); Dy (2.5), Ho (2.3); Er (3.0); Tm (2.3); Yb (38,2); Lu (25.6). The high-purity samarium oxides produced in the present study can be used as an alternative to imported products in research and development applications. (author)

  11. Synthesis of High Purity Nonsymmetric Dialkylphosphinic Acid Extractants.

    Wang, Junlian; Xie, Meiying; Liu, Xinyu; Xu, Shengming

    2017-10-19

    We present the synthesis of (2,3-dimethylbutyl)(2,4,4'-trimethylpentyl)phosphinic acid as an example to demonstrate a method for the synthesis of high purity nonsymmetric dialkylphosphinic acid extractants. Low toxic sodium hypophosphite was chosen as the phosphorus source to react with olefin A (2,3-dimethyl-1-butene) to generate a monoalkylphosphinic acid intermediate. Amantadine was adopted to remove the dialkylphosphinic acid byproduct, as only the monoalkylphosphinic acid can react with amantadine to form an amantadine∙mono-alkylphosphinic acid salt, while the dialkylphosphinic acid cannot react with amantadine due to its large steric hindrance. The purified monoalkylphosphinic acid was then reacted with olefin B (diisobutylene) to yield nonsymmetric dialkylphosphinic acid (NSDAPA). The unreacted monoalkylphosphinic acid can be easily removed by a simple base-acid post-treatment and other organic impurities can be separated out through the precipitation of the cobalt salt. The structure of the (2,3-dimethylbutyl)(2,4,4'-trimethylpentyl)phosphinic acid was confirmed by 31 P NMR, 1 H NMR, ESI-MS, and FT-IR. The purity was determined by a potentiometric titration method, and the results indicate that the purity can exceed 96%.

  12. The determination of boron in aluminium of high purity

    Cook, E.B.T.; Holan, H.

    1977-01-01

    A description is given of the investigations that led to the development of chemical methods for the determination of boron within the range 0,25 to 1,0 p.p.m. in aluminium of high purity. Methods were developed that incorporated fluorimetry, directly in solutions containing aluminium and after separation of boron by liquid-liquid extraction into 2-ethyl-1,3 hexanediol. A published spectrophotometric method, involving extraction of the BF 4 sup(-) complex with methylene blue into dichloroethane, was modified for application to alluminium samples. Details of this modified procedure and the fluorimetric-extraction procedure are appended. The precision of the methylene-blue method is about 6 percent relative and is recommended for precision and speed in preference to others. Separation of boron by distillation and spectrophotometric determination with curcumin gave low values in comparison with those obtained by the other methods. Agreement between the boron values obtained on the samples tested was good for the fluorimetric and methylene-blue spectrophotometric methods

  13. Spectroscopic Determination of Trace Contaminants in High Purity Oxygen

    Hornung, Steven D.

    2011-01-01

    Oxygen used for extravehicular activities (EVA) must be free of contaminants because a difference in a few tenths of a percent of argon or nitrogen content can mean significant reduction in available EVA time. These inert gases build up in the extravehicular mobility unit because they are not metabolized or scrubbed from the atmosphere. Measurement of oxygen purity above 99.5% is problematic, and currently only complex instruments such as gas chromatographs or mass spectrometers are used for these determinations. Because liquid oxygen boil-off from the space shuttle will no longer be available to supply oxygen for EVA use, other concepts are being developed to produce and validate high purity oxygen from cabin air aboard the International Space Station. A prototype optical emission technique capable of detecting argon and nitrogen below 0.1% in oxygen was developed at White Sands Test Facility. This instrument uses a glow discharge in reduced pressure gas to produce atomic emission from the species present. Because the atomic emission lines from oxygen, nitrogen, and argon are discrete and in many cases well-separated, trace amounts of argon and nitrogen can be detected in the ultraviolet and visible spectrum. This is a straightforward, direct measurement of the target contaminants and may lend itself to a device capable of on-orbit verification of oxygen purity. System design and optimized measurement parameters are presented.

  14. Electron beam welding of high-purity copper accelerator cells

    Delis, K.; Haas, H.; Schlebusch, P.; Sigismund, E.

    1986-01-01

    The operating conditions of accelerator cells require high thermal conductivity, low gas release in the ultrahigh vacuum, low content of low-melting metals and an extremely good surface quality. In order to meet these requirements, high-purity copper (OFHC, Grade 1, according to ASTM B 170-82 and extra specifications) is used as structural material. The prefabricated components of the accelerator cells (noses, jackets, flanges) are joined by electron beam welding, the weld seam being assessed on the basis of the same criteria as the base material. The welding procedures required depend, first, on the material and, secondly, on the geometries involved. Therefore experimental welds were made first on standardized specimens in order to study the behaviour of the material during electron beam welding and the influence of parameter variations. The welded joints of the cell design were planned on the basis of these results. Seam configuration, welding procedures and the parameters were optimized on components of original geometry. The experiments have shown that high-quality joints of this grade of copper can be produced by the electron beam welding process, if careful planning and preparation of the seams and adequate containment of the welding pool are assured. (orig.)

  15. Spall behaviors of high purity copper under sweeping detonation

    Yang, Yang, E-mail: yangyanggroup@163.com [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China); National Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Key Laboratory of Nonferrous Metals Material Science and Engineering of Ministry of Education, Central South University, Changsha 410083 (China); Zhi-qiang, Peng; Xing-zhi, Chen [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Nonferrous Metals Material Science and Engineering of Ministry of Education, Central South University, Changsha 410083 (China); Zhao-liang, Guo; Tie-gang, Tang; Hai-bo, Hu [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China); Qing-ming, Zhang [National Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

    2016-01-10

    Suites of sweeping detonation experiments were conducted to assess the spall behavior of high purity copper samples with different heat treatment histories. Incipient spall samples were obtained at different sweeping detonation condition. Metallographic and Electron Backscattered Diffraction (EBSD) analyses were performed on the soft-recovered samples. The effects of grain boundaries, grain size, crystal orientation and loading direction on the spall behaviors were discussed. Spall plane branching was found in the main spall plane of the damage samples. For similar microstructure, the area of voids increase with the increase of shock stress, and the coalescence of voids also become more obvious. Results from EBSD analysis show that the grain sizes were decreased and the grains were elongated along the direction of the plate width. Triple junctions composed of two or more general high angle boundaries are the preferred locations for intergranular damage. Voids prefer to nucleate in the grain boundaries composed of grain with high Taylor Factor (TF) than other grains. The damage areas in the grains with high TF are more severe. Boundaries close to perpendicular to the loading direction are more susceptible to void nucleation than the boundaries close to parallel to the loading direction, but the difference of voids nucleated in these two boundaries is less significant than the results obtained by plate impact experiment. It would be caused by the obliquity between the shock loading direction and the plate normal.

  16. Recent developments in high purity niobium metal production at CBMM

    Abdo, Gustavo Giovanni Ribeiro; Sousa, Clovis Antonio de Faria; Guimarães, Rogério Contato; Ribas, Rogério Marques; Vieira, Alaércio Salvador Martins; Menezes, Andréia Duarte; Fridman, Daniel Pallos; Cruz, Edmundo Burgos

    2015-01-01

    CBMM is a global supplier of high quality niobium products including pure niobium, the focus of this paper. CBMM’s position has been consolidated over three decades of producing high purity niobium metal ingots. The company supplies, among other products, commercial and reactor grade niobium ingots. One of the main uses of CBMM’s ingots is for the manufacture of particle accelerators (superconducting radio frequency – SRF – cavities), where the purity and homogeneity of niobium metal is essentially important for good performance. CBMM constantly strives to improve process controls and product quality, and is currently implementing innovations in production, research and development to further improve ingot quality. The main aim is to reduce the content of interstitial elements, such as nitrogen (N), oxygen (O), carbon (C), and hydrogen (H), starting with the raw materials through the final step of ingot production. CBMM held the first trial to produce the world’s largest-diameter niobium ingot (as cast 535 mm). The results of this initial trial presented very low levels of interstitial impurities (N, O, C, H), allowing the achievement of residual resistivity ratio (RRR) values very close to 300 in a six-melt process in an electron beam furnace. These values were reached with 850 ppm of tantalum. SRF cavities will be produced with this material in order to study the effect of low impurities and high RRR on the Q factor and accelerating gradient

  17. Mesophase Formation Stabilizes High-purity Magic-sized Clusters

    Nevers, Douglas R.; Williamson, Curtis B.; Savitzky, Benjamin H; Hadar, Ido; Banin, Uri; Kourkoutis, Lena F.; Hanrath, Tobias; Robinson, Richard D.

    2018-01-01

    Magic-sized clusters (MSCs) are renowned for their identical size and closed-shell stability that inhibit conventional nanoparticle (NP) growth processes. Though MSCs have been of increasing interest, understanding the reaction pathways toward their nucleation and stabilization is an outstanding issue. In this work, we demonstrate that high concentration synthesis (1000 mM) promotes a well-defined reaction pathway to form high-purity MSCs (>99.9%). The MSCs are resistant to typical growth and dissolution processes. Based on insights from in-situ X-ray scattering analysis, we attribute this stability to the accompanying production of a large, hexagonal organic-inorganic mesophase (>100 nm grain size) that arrests growth of the MSCs and prevents NP growth. At intermediate concentrations (500 mM), the MSC mesophase forms, but is unstable, resulting in NP growth at the expense of the assemblies. These results provide an alternate explanation for the high stability of MSCs. Whereas the conventional mantra has been that the stability of MSCs derives from the precise arrangement of the inorganic structures (i.e., closed-shell atomic packing), we demonstrate that anisotropic clusters can also be stabilized by self-forming fibrous mesophase assemblies. At lower concentration (<200 mM or >16 acid-to-metal), MSCs are further destabilized and NPs formation dominates that of MSCs. Overall, the high concentration approach intensifies and showcases inherent concentration-dependent surfactant phase behavior that is not accessible in conventional (i.e., dilute) conditions. This work provides not only a robust method to synthesize, stabilize, and study identical MSC products, but also uncovers an underappreciated stabilizing interaction between surfactants and clusters.

  18. Mesophase Formation Stabilizes High-purity Magic-sized Clusters

    Nevers, Douglas R.

    2018-01-27

    Magic-sized clusters (MSCs) are renowned for their identical size and closed-shell stability that inhibit conventional nanoparticle (NP) growth processes. Though MSCs have been of increasing interest, understanding the reaction pathways toward their nucleation and stabilization is an outstanding issue. In this work, we demonstrate that high concentration synthesis (1000 mM) promotes a well-defined reaction pathway to form high-purity MSCs (>99.9%). The MSCs are resistant to typical growth and dissolution processes. Based on insights from in-situ X-ray scattering analysis, we attribute this stability to the accompanying production of a large, hexagonal organic-inorganic mesophase (>100 nm grain size) that arrests growth of the MSCs and prevents NP growth. At intermediate concentrations (500 mM), the MSC mesophase forms, but is unstable, resulting in NP growth at the expense of the assemblies. These results provide an alternate explanation for the high stability of MSCs. Whereas the conventional mantra has been that the stability of MSCs derives from the precise arrangement of the inorganic structures (i.e., closed-shell atomic packing), we demonstrate that anisotropic clusters can also be stabilized by self-forming fibrous mesophase assemblies. At lower concentration (<200 mM or >16 acid-to-metal), MSCs are further destabilized and NPs formation dominates that of MSCs. Overall, the high concentration approach intensifies and showcases inherent concentration-dependent surfactant phase behavior that is not accessible in conventional (i.e., dilute) conditions. This work provides not only a robust method to synthesize, stabilize, and study identical MSC products, but also uncovers an underappreciated stabilizing interaction between surfactants and clusters.

  19. Experience with dedicated ultra fast solid state cardiac gamma camera: technologist perspective

    Parab, Anil; Gaikar, Anil; Patil, Kashinath; Lele, V.

    2010-01-01

    Full text: To describe technologist perspective of working with ultra fast solid state gamma camera and comparison with conventional dual head gamma camera. Material and Methods: 900 Myocardial Perfusion scan were carried out on dedicated solid state detector cardiac camera between 1st February 2010 till 29th August 2010. 27 studies were done back to back on a conventional dual head gamma camera. In 2 cases dual head isotope imaging was done (Thallium+ 99m Tc-tetrofosmin). Rest stress protocol was used in 600 patients and stress - rest protocol was used in 300. 1:3 ratio of injected activity was maintained for both protocols (5 mCi for 1st study and 15 mCi for second study). For Rest - Stress protocol, 5 mCi of 99m Tc - Tetrofosmin was injected at rest, 40 minutes later, 5 min image was acquired on the solid state detector. Patient was then stressed. 15 mCi 99m Tc - Tetrofosmin was injected at peak stress. Images were acquired 20 minutes later for 3 minutes (total duration of study 90-100 min). For stress rest protocol, 5 mCi 99m Tc - Tetrofosmin was injected at peak stress. 5 mCi images were acquired 20 minutes later. Rest injection of 15 mCi was given 1 hour post stress injection. Rest images were acquired 40 minutes after rest injection (total duration of study 110-120 min). Results: We observed even with lesser amount activity and acquisition time of 5 min/cardiac scan it showed high sensitivity count rate over 2.2-4.7 kcps (10 times more counts than standard gamma camera). System gives better energy resolution < 7%. Better image contrast. Dual isotope imaging can be possible. Spatial resolution 4.3-4.9 mm. Excellent quality images were obtained using low activities (5 mCi/15 mCi) using 1/3rd the acquisition time compared to conventional dual head gamma camera Even in obese patients 7 mCi/21 mCi activity yielded excellent images at 1/3 rd acquisition time Quick acquisition resulted in greater patient comfort and no motion artifact also due to non rotation of

  20. TU-H-206-01: An Automated Approach for Identifying Geometric Distortions in Gamma Cameras

    Mann, S; Nelson, J [Clinical Imaging Physics Group and Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Samei, E [Clinical Imaging Physics Group and Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Departments of Physics, Electrical and Computer Engineering, and Biomedical Engineering, and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States)

    2016-06-15

    Purpose: To develop a clinically-deployable, automated process for detecting artifacts in routine nuclear medicine (NM) quality assurance (QA) bar phantom images. Methods: An artifact detection algorithm was created to analyze bar phantom images as part of an ongoing QA program. A low noise, high resolution reference image was acquired from an x-ray of the bar phantom with a Philips Digital Diagnost system utilizing image stitching. NM bar images, acquired for 5 million counts over a 512×512 matrix, were registered to the template image by maximizing mutual information (MI). The MI index was used as an initial test for artifacts; low values indicate an overall presence of distortions regardless of their spatial location. Images with low MI scores were further analyzed for bar linearity, periodicity, alignment, and compression to locate differences with respect to the template. Findings from each test were spatially correlated and locations failing multiple tests were flagged as potential artifacts requiring additional visual analysis. The algorithm was initially deployed for GE Discovery 670 and Infinia Hawkeye gamma cameras. Results: The algorithm successfully identified clinically relevant artifacts from both systems previously unnoticed by technologists performing the QA. Average MI indices for artifact-free images are 0.55. Images with MI indices < 0.50 have shown 100% sensitivity and specificity for artifact detection when compared with a thorough visual analysis. Correlation of geometric tests confirms the ability to spatially locate the most likely image regions containing an artifact regardless of initial phantom orientation. Conclusion: The algorithm shows the potential to detect gamma camera artifacts that may be missed by routine technologist inspections. Detection and subsequent correction of artifacts ensures maximum image quality and may help to identify failing hardware before it impacts clinical workflow. Going forward, the algorithm is being

  1. A clinical gamma camera-based pinhole collimated system for high resolution small animal SPECT imaging

    Mejia, J.; Galvis-Alonso, O.Y., E-mail: mejia_famerp@yahoo.com.b [Faculdade de Medicina de Sao Jose do Rio Preto (FAMERP), SP (Brazil). Dept. de Biologia Molecular; Castro, A.A. de; Simoes, M.V. [Faculdade de Medicina de Sao Jose do Rio Preto (FAMERP), SP (Brazil). Dept. de Clinica Medica; Leite, J.P. [Universidade de Sao Paulo (FMRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Medicina. Dept. de Neurociencias e Ciencias do Comportamento; Braga, J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Astrofisica

    2010-11-15

    The main objective of the present study was to upgrade a clinical gamma camera to obtain high resolution tomographic images of small animal organs. The system is based on a clinical gamma camera to which we have adapted a special-purpose pinhole collimator and a device for positioning and rotating the target based on a computer-controlled step motor. We developed a software tool to reconstruct the target's three-dimensional distribution of emission from a set of planar projections, based on the maximum likelihood algorithm. We present details on the hardware and software implementation. We imaged phantoms and heart and kidneys of rats. When using pinhole collimators, the spatial resolution and sensitivity of the imaging system depend on parameters such as the detector-to-collimator and detector-to-target distances and pinhole diameter. In this study, we reached an object voxel size of 0.6 mm and spatial resolution better than 2.4 and 1.7 mm full width at half maximum when 1.5- and 1.0-mm diameter pinholes were used, respectively. Appropriate sensitivity to study the target of interest was attained in both cases. Additionally, we show that as few as 12 projections are sufficient to attain good quality reconstructions, a result that implies a significant reduction of acquisition time and opens the possibility for radiotracer dynamic studies. In conclusion, a high resolution single photon emission computed tomography (SPECT) system was developed using a commercial clinical gamma camera, allowing the acquisition of detailed volumetric images of small animal organs. This type of system has important implications for research areas such as Cardiology, Neurology or Oncology. (author)

  2. Performance tests of two portable mini gamma cameras for medical applications

    Sanchez, F.; Fernandez, M. M.; Gimenez, M.; Benlloch, J. M.; Rodriguez-Alvarez, M. J.; Garcia de Quiros, F.; Lerche, Ch. W.; Pavon, N.; Palazon, J. A.; Martinez, J.; Sebastia, A.

    2006-01-01

    We have developed two prototypes of portable gamma cameras for medical applications based on a previous prototype designed and tested by our group. These cameras use a CsI(Na) continuous scintillation crystal coupled to the new flat-panel-type multianode position-sensitive photomultiplier tube, H8500 from Hamamatsu Photonics. One of the prototypes, mainly intended for intrasurgical use, has a field of view of 44x44 mm 2 , and weighs 1.2 kg. Its intrinsic resolution is better than 1.5 mm and its energy resolution is about 13% at 140 keV. The second prototype, mainly intended for osteological, renal, mammary, and endocrine (thyroid, parathyroid, and suprarenal) scintigraphies, weighs a total of 2 kg. Its average spatial resolution is 2 mm; it has a field of view of 95x95 mm 2 , with an energy resolution of about 15% at 140 keV. The main advantages of these gamma camera prototypes with respect to those previously reported in the literature are high portability and low weight, with no significant loss of sensitivity and spatial resolution. All the electronic components are packed inside the mini gamma cameras, and no external electronic devices are required. The cameras are only connected through the universal serial bus port to a portable PC. In this paper, we present the design of the cameras and describe the procedures that have led us to choose their configuration together with the most important performance features of the cameras. For one of the prototypes, clinical tests on melanoma patients are presented and images are compared with those obtained with a conventional camera

  3. Value of coincidence gamma camera PET for diagnosing head and neck tumors: functional imaging and image coregistration

    Dresel, S.; Brinkbaeumer, K.; Schmid, R.; Hahn, K.

    2001-01-01

    54 patients suffering from head and neck tumors (30 m, 24 f, age: 32-67 years) were examined using dedicated PET and coincidence gamma camera PET after injection of 185-350 MBq [ 18 F]FDG. Examinations were carried out on the dedicated PET first (Siemens ECAT Exact HR+) followed by a scan on the coincidence gamma camera PET (Picker Prism 2000 XP-PCD, Marconi Axis g-PET 2 AZ). Dedicated PET was acquired in 3D mode, coincidence gamma camera PET was performed in list mode using an axial filter. Reconstruction of data was performed iteratively on both, dedicated PET and coincidence gamma camera PET. All patients received a CT scan in multislice technique (Siemens Somatom Plus 4, Marconi MX 8000). Image coregistration was performed on an Odyssey workstation (Marconi). All findings have been verified by the gold standard histology or in case of negative histology by follow-up. Results: Using dedicated PET the primary or recurrent lesion was correctly diagnosed in 47/48 patients, using coincidence gamma camera PET in 46/48 patients and using CT in 25/48 patients. Metastatic disease in cervical lymph nodes was diagnosed in 17/18 patients with dedicated PET, in 16/18 patients with coincidence gamma camera PET and in 15/18 with CT. False-positive results with regard to lymph node metastasis were seen with one patient for dedicated PET and hybrid PET, respectively, and with 18 patients for CT. In a total of 11 patients unknown metastatic lesions were seen with dedicated PET and with coincidence gamma camera PET elsewhere in the body (lung: n = 7, bone: n = 3, liver: n = 1). Additional malignant disease other than the head and neck tumor was found in 4 patients. (orig.) [de

  4. Computer assisted collimation gamma camera: A new approach to imaging contaminated tissues

    Quartuccio, M.; Franck, D.; Pihet, P.; Begot, S.; Jeanguillaume, C.

    2000-01-01

    Measurement systems with the capability of imaging tissues contaminated with radioactive materials would find relevant applications in medical physics research and possibly in health physics. The latter in particular depends critically on the performance achieved for sensitivity and spatial resolution. An original approach of computer assisted collimation gamma camera (French acronym CACAO) which could meet suitable characteristics has been proposed elsewhere. CACAO requires detectors with high spatial resolution. The present work was aimed at investigating the application of the CACAO principle on a laboratory testing bench using silicon detectors made of small pixels. (author)

  5. Computer assisted collimation gamma camera: A new approach to imaging contaminated tissues

    Quartuccio, M.; Franck, D.; Pihet, P.; Begot, S.; Jeanguillaume, C

    2000-07-01

    Measurement systems with the capability of imaging tissues contaminated with radioactive materials would find relevant applications in medical physics research and possibly in health physics. The latter in particular depends critically on the performance achieved for sensitivity and spatial resolution. An original approach of computer assisted collimation gamma camera (French acronym CACAO) which could meet suitable characteristics has been proposed elsewhere. CACAO requires detectors with high spatial resolution. The present work was aimed at investigating the application of the CACAO principle on a laboratory testing bench using silicon detectors made of small pixels. (author)

  6. Study of the feasibility of a compact gamma camera for real-time cancer assessment

    Caballero Ontanaya, Luis

    2017-01-01

    Results from the simulations of a Compton gamma camera based on compact configuration of detectors consisting in two detection modules, each of them having two stages of high-resolution position- and energy sensitive radiation detectors operated in time-coincidence are presented. Monolithic scintillation crystals instead of pixelated crystals in order to reduce dead areas have been simulated. In order to study the system feasibility to produce real-time images, different setups are considered. Performance in terms of acquisition times have been calculated to determine the real-time capabilities and limitations of such a system.

  7. MO-AB-206-02: Testing Gamma Cameras Based On TG177 WG Report

    Halama, J. [Loyola Univ. Medical Center (United States)

    2016-06-15

    This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Be able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images

  8. Measurement of total-body cobalt-57 vitamin B12 absorption with a gamma camera

    Cardarelli, J.A.; Slingerland, D.W.; Burrows, B.A.; Miller, A.

    1985-01-01

    Previously described techniques for the measurement of the absorption of [ 57 Co]vitamin B 12 by total-body counting have required an iron room equipped with scanning or multiple detectors. The present study uses simplifying modifications which make the technique more available and include the use of static geometry, the measurement of body thickness to correct for attenuation, a simple formula to convert the capsule-in-air count to a 100% absorption count, and finally the use of an adequately shielded gamma camera obviating the need of an iron room

  9. Easy method to measure radioactive waste with a gamma-camera detector

    Murat, C.; Barrau, C.

    2007-01-01

    The aim of this technical note is to evaluate an easy method to measure 99m Tc samples with an activity of 1000, 100 and 10 Bq/L. This study is performed with a gamma camera detector in two departments of nuclear medicine in Avignon and in Nimes. We develop a procedure to measure 99m Tc radioactive waste at the two hospitals output in accordance with the D.G.S./D.H.O.S. no. 2001/323 circular requests of the Ministry for Employment and Solidarity. (authors)

  10. A 3D high-resolution gamma camera for radiopharmaceutical studies with small animals

    Loudos, G K; Giokaris, N D; Styliaris, E; Archimandritis, S C; Varvarigou, A D; Papanicolas, C N; Majewski, S; Weisenberger, D; Pani, R; Scopinaro, F; Uzunoglu, N K; Maintas, D; Stefanis, K

    2003-01-01

    The results of studies conducted with a small field of view tomographic gamma camera based on a Position Sensitive Photomultiplier Tube are reported. The system has been used for the evaluation of radiopharmaceuticals in small animals. Phantom studies have shown a spatial resolution of 2 mm in planar and 2-3 mm in tomographic imaging. Imaging studies in mice have been carried out both in 2D and 3D. Conventional radiopharmaceuticals have been used and the results have been compared with images from a clinically used system.

  11. Emission computerized axial tomography from multiple gamma-camera views using frequency filtering.

    Pelletier, J L; Milan, C; Touzery, C; Coitoux, P; Gailliard, P; Budinger, T F

    1980-01-01

    Emission computerized axial tomography is achievable in any nuclear medicine department from multiple gamma camera views. Data are collected by rotating the patient in front of the camera. A simple fast algorithm is implemented, known as the convolution technique: first the projection data are Fourier transformed and then an original filter designed for optimizing resolution and noise suppression is applied; finally the inverse transform of the latter operation is back-projected. This program, which can also take into account the attenuation for single photon events, was executed with good results on phantoms and patients. We think that it can be easily implemented for specific diagnostic problems.

  12. Impact of intense x-ray pulses on a NaI(Tl)-based gamma camera

    Koppert, W. J. C.; van der Velden, S.; Steenbergen, J. H. L.; de Jong, H. W. A. M.

    2018-03-01

    In SPECT/CT systems x-ray and γ-ray imaging is performed sequentially. Simultaneous acquisition may have advantages, for instance in interventional settings. However, this may expose a gamma camera to relatively high x-ray doses and deteriorate its functioning. We studied the NaI(Tl) response to x-ray pulses with a photodiode, PMT and gamma camera, respectively. First, we exposed a NaI(Tl)-photodiode assembly to x-ray pulses to investigate potential crystal afterglow. Next, we exposed a NaI(Tl)-PMT assembly to 10 ms LED pulses (mimicking x-ray pulses) and measured the response to flashing LED probe-pulses (mimicking γ-pulses). We then exposed the assembly to x-ray pulses, with detector entrance doses of up to 9 nGy/pulse, and analysed the response for γ-pulse variations. Finally, we studied the response of a Siemens Diacam gamma camera to γ-rays while exposed to x-ray pulses. X-ray exposure of the crystal, read out with a photodiode, revealed 15% afterglow fraction after 3 ms. The NaI(Tl)-PMT assembly showed disturbances up to 10 ms after 10 ms LED exposure. After x-ray exposure however, responses showed elevated baselines, with 60 ms decay-time. Both for x-ray and LED exposure and after baseline subtraction, probe-pulse analysis revealed disturbed pulse height measurements shortly after exposure. X-ray exposure of the Diacam corroborated the elementary experiments. Up to 50 ms after an x-ray pulse, no events are registered, followed by apparent energy elevations up to 100 ms after exposure. Limiting the dose to 0.02 nGy/pulse prevents detrimental effects. Conventional gamma cameras exhibit substantial dead-time and mis-registration of photon energies up to 100 ms after intense x-ray pulses. This is due PMT limitations and due to afterglow in the crystal. Using PMTs with modified circuitry, we show that deteriorative afterglow effects can be reduced without noticeable effects on the PMT performance, up to x-ray pulse doses of 1 nGy.

  13. Hydra phantom applicability for carrying out tests of field uniformity in gamma cameras

    Aragao Filho, Geraldo L.; Oliveira, Alex C.H.

    2014-01-01

    Nuclear Medicine is a medical modality that makes use of radioactive material 'in vivo' in humans, making them a temporary radioactive source. The radiation emitted by the patient's body is detected by a specific equipment, called a gamma camera, creates an image showing the spatial and temporal biodistribution of radioactive material administered to the patient. Therefore, it's of fundamental importance a number of specific measures to make sure that procedure be satisfactory, called quality control. To Nuclear Medicine, quality control of gamma camera has the purpose of ensuring accurate scintillographic imaging, truthful and reliable for the diagnosis, guaranteeing visibility and clarity of details of structures, and also to determine the frequency and the need for preventive maintenance of equipment. To ensure the quality control of the gamma camera it's necessary to use some simulators, called phantom, used in Nuclear Medicine to evaluate system performance, system calibration and simulation of injuries. The goal of this study was to validate a new simulator for nuclear medicine, the Hydra phantom. The phantom was initially built for construction of calibration curves used in radiotherapy planning and quality control in CT. It has similar characteristics to specific phantoms in nuclear medicine, containing inserts and water area. Those inserts are regionally sourced materials, many of them are already used in the literature and based on information about density and interaction of radiation with matter. To verify its efficiency in quality control in Nuclear Medicine, was performed a test for uniformity field, one of the main tests performed daily, so we can verify the ability of the gamma camera to reproduce a uniform distribution of the administered activity in the phantom, been analysed qualitatively, through the image, and quantitatively, through values established for Central Field Of View (CFOV) and Useful Field Of View (UFOV). Also, was evaluated their

  14. Approaches to contamination problems of agricultural land using Na(I) Tl spectrometer and gamma camera

    Yin, Yong-Gen; Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; Fujimaki, Shu; Yamaguchi, Mitsutaka; Tanoi, Keitaro; Nakanishi, Tomoko M.; Chino, Mitsuo; Nakamura, Shin-ichi; Watabe, Hiroshi; Yamamoto, Seiichi

    2012-01-01

    The severe accident of Fukushima Daiichi Nuclear Power Plant made a large area of agricultural land contaminated with radioactive cesium (Cs-134 and 137). Quantitative analysis for radioactivity (discriminating for Cs-134 and Cs-137) taken in vegetables from the land was carried out using NaI (Tl) scintillation spectrometer. Development of gamma camera for their imaging due to Cs 137 was performed. The shape of the peaks in the spectrum, baseline suppression, a solution of lines overlapping, enhancement of high-resolution were studied. Furthermore, the effect of water on cesium absorbing and transferring process from the root to the tissue was studied. (S. Ohno)

  15. MO-AB-206-02: Testing Gamma Cameras Based On TG177 WG Report

    Halama, J.

    2016-01-01

    This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Be able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images

  16. Single photon emission computed tomography of the brain with a rotating gamma camera

    Biersack, H J; Knopp, R; Winkler, C; Wappenschmidt, J

    1981-08-01

    In 471 patients SPECT of the brain was performed in addition to conventional serial brain scintigraphy using a rotating gamma camera (GAMMATOME T 9000). 23 patients had tumorous lesions, 26 had vascular lesions, and 422 patients revealed normal brain findings. 5 of the 23 patients with tumorous lesion and 5 of the 12 patients with vascular lesion (anamnesis shorter than 4 weeks) showed positive SPECT results but false negative conventional brain scans. Specificity could be improved up to 98% (412 out of 422 patients) using SPECT and conventional scintigraphy.

  17. Survey of potential use of dynamic line phantom for quality control of Gamma camera

    Trindev, P.; Ozturk, N.

    2004-01-01

    Different phantoms, used to evaluate the essential for image quality parameters of gamma cameras in order to avoid artefacts, are presented. The prices are significant and it is a sensible approach to optimise the type and number of phantoms necessary for quality control. Among all phantoms the price of 'Dynamic Line Phantom' (DLP) is impressive, but it is announced to substitute several 'passive' and 'active' phantoms. The goal of this paper is to justify this statement. The programs, based on image profile are discussed in the paper and the practical uses of the different programs are given

  18. The Hydrometallurgical Extraction and Recovery of High-Purity Silver

    Hoffmann, James E.

    2012-06-01

    -bearing inputs, will be described in detail to demonstrate how typical chemical engineering unit process and unit operations have supplanted classic smelting and fire refining techniques. The Kennecott Copper Company, which has operated a hydrometallurgical circuit successfully for the recovery of high-purity silver from the slimes wet chlorination residue, has permitted me to provide some operation information and results using the technology. Both Phelps Dodge and Kennecott should be recognized for their forward-looking attitude in undertaking the conversion of conceptual chemistry into successful, full-scale plants. The process as employed at Phelps Dodge is discussed at length in reference (J.E. Hoffmann and B. Wesstrom: Hydrometallurgy, 1994, vol. 94, pp. 69-105).

  19. A light hydrocarbon fuel processor producing high-purity hydrogen

    Löffler, Daniel G.; Taylor, Kyle; Mason, Dylan

    This paper discusses the design process and presents performance data for a dual fuel (natural gas and LPG) fuel processor for PEM fuel cells delivering between 2 and 8 kW electric power in stationary applications. The fuel processor resulted from a series of design compromises made to address different design constraints. First, the product quality was selected; then, the unit operations needed to achieve that product quality were chosen from the pool of available technologies. Next, the specific equipment needed for each unit operation was selected. Finally, the unit operations were thermally integrated to achieve high thermal efficiency. Early in the design process, it was decided that the fuel processor would deliver high-purity hydrogen. Hydrogen can be separated from other gases by pressure-driven processes based on either selective adsorption or permeation. The pressure requirement made steam reforming (SR) the preferred reforming technology because it does not require compression of combustion air; therefore, steam reforming is more efficient in a high-pressure fuel processor than alternative technologies like autothermal reforming (ATR) or partial oxidation (POX), where the combustion occurs at the pressure of the process stream. A low-temperature pre-reformer reactor is needed upstream of a steam reformer to suppress coke formation; yet, low temperatures facilitate the formation of metal sulfides that deactivate the catalyst. For this reason, a desulfurization unit is needed upstream of the pre-reformer. Hydrogen separation was implemented using a palladium alloy membrane. Packed beds were chosen for the pre-reformer and reformer reactors primarily because of their low cost, relatively simple operation and low maintenance. Commercial, off-the-shelf balance of plant (BOP) components (pumps, valves, and heat exchangers) were used to integrate the unit operations. The fuel processor delivers up to 100 slm hydrogen >99.9% pure with <1 ppm CO, <3 ppm CO 2. The

  20. A pixellated gamma-camera based on CdTe detectors clinical interests and performances

    Chambron, J; Eclancher, B; Scheiber, C; Siffert, P; Hage-Ali, M; Regal, R; Kazandjian, A; Prat, V; Thomas, S; Warren, S; Matz, R; Jahnke, A; Karman, M; Pszota, A; Németh, L

    2000-01-01

    A mobile gamma camera dedicated to nuclear cardiology, based on a 15 cmx15 cm detection matrix of 2304 CdTe detector elements, 2.83 mmx2.83 mmx2 mm, has been developed with a European Community support to academic and industrial research centres. The intrinsic properties of the semiconductor crystals - low-ionisation energy, high-energy resolution, high attenuation coefficient - are potentially attractive to improve the gamma-camera performances. But their use as gamma detectors for medical imaging at high resolution requires production of high-grade materials and large quantities of sophisticated read-out electronics. The decision was taken to use CdTe rather than CdZnTe, because the manufacturer (Eurorad, France) has a large experience for producing high-grade materials, with a good homogeneity and stability and whose transport properties, characterised by the mobility-lifetime product, are at least 5 times greater than that of CdZnTe. The detector matrix is divided in 9 square units, each unit is composed ...

  1. PET with a coincidence gamma camera: results in selected oncological questions

    Lauer, I.; Haase, A; Adam, S.; Prueter, I.; Richter, E.; Baehre, M.

    2001-01-01

    Since early 1997, about 1660 investigations with coincidence gamma camera PET (CGC-PET) have been performed in our department, mostly undertaken for oncological questions. Based on these data, several retrospective and prospective studies were performed. In the following, the results in CUP (cancer of unknown primary) syndrome, melanoma and malignant lymphoma are presented. Methods: CGC-PET was performed after application of 250-350 MBq [ 18 F]FDG using a coincidence double head gamma camera with 19 mm Nal cristal. CUP-Syndrome: After completing conventional diagnostic procedures, 32 patients have been examined in a prospective study, including 25 patients with recently detected CUP and 7 patients undergoing restaging after therapy. Localization of the primary tumor was successful in 12 (38%) cases. Melanoma: We evaluated 50 studies in 41 patients suffering from melanoma, retrospectively. CGC-PET showed a sensitivity of 76%, and a specificity of 94%. In comparison to conventional diagnostic methods, CGC-PET delineated important additional information in 16%. CGC-PET was superior to morphological diagnostic tools in the differentiation between residual scar tissue and active tumor following immunochemotherapy. Malignant lymphoma: 29 CGC-PET in 29 patients were performed for staging of malignant lymphoma, sensitivity was 86% versus 88% for CT. Overall CGC-PET showed additional information to conventional diagnostic methods, but revealed problems in detecting small infiltrations of organs. In restaging malignant melanoma (26 patients, 33 studies), specificity of CGC-PET was superior to conventional diagnostics (92% versus 35%). (orig.) [de

  2. F-18 FDG PET with coincidence detection, dual-head gamma camera, initial experience in oncology

    Chu, J.M.G.; Pocock, N.; Quach, T.; Camden, B.M.C. [Liverpool Health Services, Liverpool, NSW (Australia). Department of Nuclear Medicine and Clinical Ultrasound

    1998-06-01

    Full text: The development of Co-incidence Detection (CD) in gamma camera technology has allowed the use of positron radiopharmaceuticals in clinical practice without dedicated PET facilities. We report our initial experience of this technology in Oncological applications. All patients were administered 200 MBq of F- 18 FDG intravenously in a fasting state, with serum glucose below 8.9 mmol/L., and hydration well maintained. Tomography was performed using an ADAC Solus Molecular Co-incidence Detection (MCD) dual-head gamma camera, 60 minutes after administration and immediately after voiding. Tomography of the torso required up to three collections depending on the length of the patient, with each collection requiring 32 steps of 40 second duration, and a 50% overlap. Tomography of the brain required a single collection with 32 steps of 80 seconds. Patients were scanned in the supine position. An iterative reconstruction algorithm was employed without attenuation correction. All patients had histologically confirmed malignancy. Scan findings were correlated with results of all conventional diagnostic imaging procedures that were pertinent to the evaluation and management of each individual patient`s disease. Correlation with tumour type and treatment status was also undertaken. F-18 FDG uptake as demonstrated by CD-PET was increased in tumour bearing sites. The degree of increased uptake varied with tumour type and with treatment status. Our initial experience with CD-PET has been very encouraging, and has led us to undertake prospective short and long term studies to define its role in oncology

  3. Defining the lung outline from a gamma camera transmission attenuation map

    Fleming, John S; Pitcairn, Gary; Newman, Stephen

    2006-01-01

    Segmentation of the lung outline from gamma camera transmission images of the thorax is useful in attenuation correction and quantitative image analysis. This paper describes and compares two threshold-based methods of segmentation. Simulated gamma camera transmission images of test objects were used to produce a knowledge base of the variation of threshold defining the lung outline with image resolution and chest wall thickness. Two segmentation techniques based on global (GT) and context-sensitive (CST) thresholds were developed and evaluated in simulated transmission images of realistic thoraces. The segmented lung volumes were compared to the true values used in the simulation. The mean distances between segmented and true lung surface were calculated. The techniques were also applied to three real human subject transmission images. The lung volumes were estimated and the segmentations were compared visually. The CST segmentation produced significantly superior segmentations than the GT technique in the simulated data. In human subjects, the GT technique underestimated volumes by 13% compared to the CST technique. It missed areas that clearly belonged to the lungs. In conclusion, both techniques segmented the lungs with reasonable accuracy and precision. The CST approach was superior, particularly in real human subject images

  4. The use of a Micromegas as a detector for gamma camera

    Barbouchi, Asma; Trabelsi, Adel

    2008-01-01

    The micromegas (Micro Mesh Gaseaous) is a gas detector; it was developed by I.Giomattaris and G.Charpak for application in the field of experimental particle physics. But the polyvalence of this detector makes it to be used in several areas such as medical imaging. This detector has an X-Y readout capability of resolution less than 100μm, an energy resolution down to 14% for energy range 1-10 keV and an overall efficiency of 70%. Monte carlo simulation is widely used in nuclear medicine. It allows predicting the behaviour of system. Gate (Geant4 for Application Tomography Emission) is a platform for monte carlo simulation. It is dedicated to PET/SPECT (Position Emission Tomography / single Photon Emission Tomography) applications. Our goal is to model a gamma camera that use a Micromegas as a detector and to compare their performances (energy resolution, point spread function...) with those of a scintillated gamma camera by using Gate

  5. SiPM arrays and miniaturized readout electronics for compact gamma camera

    Dinu, N., E-mail: dinu@lal.in2p3.fr [Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay (France); Imando, T. Ait; Nagai, A. [Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay (France); Pinot, L. [Laboratory of Imaging and Modelisation in Neurobiology and Cancerology, IN2P3, CNRS, Orsay (France); Puill, V. [Laboratory of Linear Accelerator, IN2P3, CNRS, Orsay (France); Callier, S. [Omega Microelectronics Group, CNRS, Palaiseau (France); Janvier, B.; Esnault, C.; Verdier, M.-A. [Laboratory of Imaging and Modelisation in Neurobiology and Cancerology, IN2P3, CNRS, Orsay (France); Raux, L. [Omega Microelectronics Group, CNRS, Palaiseau (France); Vandenbussche, V.; Charon, Y.; Menard, L. [Laboratory of Imaging and Modelisation in Neurobiology and Cancerology, IN2P3, CNRS, Orsay (France)

    2015-07-01

    This article reports on the design and features of a very compact and light gamma camera based on SiPM arrays and miniaturized readout electronics dedicated to tumor localization during radio-guided cancer surgery. This gamma camera, called MAGICS, is composed of four (2×2) photo-detection elementary modules coupled to an inorganic scintillator. The 256 channels photo-detection system covers a sensitive area of 54×53 m{sup 2}. Each elementary module is based on four (2×2) SiPM monolithic arrays, each array consisting of 16 SiPM photo-sensors (4×4) with 3×3 mm{sup 2} sensitive area, coupled to a miniaturized readout electronics and a dedicated ASIC. The overall dimensions of the electronics fit the size of the detector, enabling to assemble side-by-side several elementary modules in a close-packed arrangement. The preliminary performances of the system are very encouraging, showing an energy resolution of 9.8% and a spatial resolution of less than 1 mm at 122 keV.

  6. Survey of Current Status of Quality Control of Gamma Cameras in Republic of Korea

    Choe, Jae Gol; Joh, Cheol Woo

    2008-01-01

    It is widely recognized that good quality control (QC) program is essential for adequate imaging diagnosis using gamma camera. The purpose of this study is to survey the current status of QC of gamma cameras in Republic of Korea for implementing appropriate nationwide quality control guidelines and programs. A collection of data is done for personnel, equipment and appropriateness of each nuclear medicine imaging laboratory's' quality control practice. This survey is done by collection of formatted questionnaire by mails, e mails or interviews. We also reviewed the current recommendations concerning quality assurance by international societies. This survey revealed that practice of quality control is irregular and not satisfactory. The irregularity of the QC practice seems due partly to the lack of trained personnel, equipment, budget, time and hand-on guidelines. The implementation of QC program may cause additional burden to the hospitals, patients and nuclear medicine laboratories. However, the benefit of a good QC program is obvious that the hospitals can provide good quality nuclear medicine imaging studies to the patients. It is important to use least cumbersome QC protocol, to educate the nuclear medicine and hospital administrative personnel concerning QC, and to establish national QC guidelines to help each individual nuclear medicine laboratory

  7. Radioimmunological determination of alphafetoprotein and gamma camera scintigraphy in patients with tumours of the testes

    Milkov, V.; Sultanov, S.

    1989-01-01

    By means of radioimmunological method the blood serum concentrations of alphafetoprotein (AFP) were investigated in 35 patients with histologically confirmed tumours of the testes prior to surgical intervention. Parallely in all patients gamma camera scintigraphy of the testes was performed. Seven of all investigated 15 patients with seminoma of the testes had increased concentrations of AFP in the blood serum. In 7 of the examinated 10 patients with diagnosis teratoma of the testes increased blood serum concentrations of AFP were established, while 6 of the examined patients with embryonic tumour of the testis had increased blood serum concentrations of AFP. In comparison with the results established in the control group of 30 healthy males, this increase of AFP was statistically reliable. All examined patients showed positive scintigraphic findings, which confirmed the diagnosis of tumour of the testes. It is concluded that the parallel determination of blood serum AFP and gamma camera investigation of the testes could be successfully apllied in the diagnosis of these malignant diseases

  8. Characteristics of Multihole Collimator Gamma Camera Simulation Modeled Using MCNP5

    Saripan, M. I.; Mashohor, S.; Adnan, W. A. Wan; Marhaban, M. H.; Hashim, S.

    2008-01-01

    This paper describes the characteristics of the multihole collimator gamma camera that is simulated using the combination of the Monte Carlo N-Particles Code (MCNP) version 5 and in-house software. The model is constructed based on the GCA-7100A Toshiba Gamma Camera at the Royal Surrey County Hospital, Guildford, Surrey, UK. The characteristics are analyzed based on the spatial resolution of the images detected by the Sodium Iodide (NaI) detector. The result is recorded in a list-mode file referred to as a PTRAC file within MCNP5. All pertinent nuclear reaction mechanisms, such as Compton and Rayleigh scattering and photoelectric absorption are undertaken by MCNP5 for all materials encountered by each photon. The experiments were conducted on Tl-201, Co-57, Tc-99 m and Cr-51 radio nuclides. The comparison of full width half maximum value of each datasets obtained from experimental work, simulation and literature are also reported in this paper. The relationship of the simulated data is in agreement with the experimental results and data obtained in the literature. A careful inspection at each of the data points of the spatial resolution of Tc-99 m shows a slight discrepancy between these sets. However, the difference is very insignificant, i.e. less than 3 mm only, which corresponds to a size of less than 1 pixel only (of the segmented detector)

  9. Gamma camera imaging of bilateral adrenocartical hyperplasia and adrenal tumors in the dog

    Mulnix, J.A.; Van den Brom, W.E.; Lubberink, A.A.; de Bruijne, J.J.; Rijnberk, A.

    1976-01-01

    Gamma camera imaging of the adrenal glands was done in 8 dogs with hyperadrenocorticism and 4 normal dogs given intravenous injections of 131I-19-iodocholesterol. In normal dogs, both adrenal glands could be visualized separately, and there was no difficulty in distinguishing among the images of normal glands, hyperplastic glands, and functional adrenal tumors. In addition, gamma camera imaging enabled the correct surgical site to be selected for removal of adrenal tumors. Hyperadrenocorticism was diagnosed in 8 dogs by evaluation of urinary 17-hydroxycorticosteroid (OHCS) excretion rates, urinary 17-OHCS and plasma 11 beta-OHCS responses to dexamethasone suppression of endogenous adrenocorticotropin (ACTH) secretion, and plasma 11 beta-OHCS response to intravenous administration of ACTH. Base line 17-OHCS excretion increased in 5 of the 8 dogs. Plasma 11 beta-OHCS concentrations were not decreased by dexamethasone administration in the 4 dogs subsequently found to have adrenal tumors; however, there was an exaggerated increase in plasma 11 beta-OHCS concentration after administration of ACTH in 3 of the 4 dogs which had bilateral adrenocortical hyperplasia

  10. An operative gamma camera for sentinel lymph node procedure in case of breast cancer

    Salvador, S; Mathelin, C; Guyonne, J; Huss, D

    2007-01-01

    Large field of view gamma cameras are widely used to perform lymphoscintigraphy in the sentinel lymph nodes (SLN) procedure in case of breast cancer. However, they are not specified for this application and their sizes do not enable their use in the operative room to control the excision of the all SLN. We present the results obtained with a prototype of a new mini gamma camera developed especially for the operative lymphoscintigraphy of the axillary area in case of breast cancer. This prototype is composed of 10 mm thick parallel lead collimator, a 2 mm thick GSO:Ce inorganic scintillating crystal from Hitachi and a Hamamatsu H8500 flat panel multianode (64 channels) photomultiplier tube (MAPMT) equipped with a dedicated electronics. Its actual field of view is 50 × 50mm2. The gamma interaction position in the GSO scintillating plate is obtained by calculating the center of gravity of the fired MAPMT channels. The measurements performed with this prototype demonstrate the usefulness of this mini gamma camer...

  11. Comparison of the barium test meal and the gamma camera scanning technic in measuring gastric emptying

    Perkel, M.S.; Fajman, W.A.; Hersh, T.

    1981-09-01

    In 21 patients with nonresected stomachs and symptoms of delayed gastric emptying, obstruction was excluded by upper gastrointestinal series and upper endoscopy; all had abnormal results of barium test meal (BTM) study. Each had repeat BTM after the administration of 10 mg of metoclopramide. Each patient also had two gamma camera studies after a technetium Tc 99m sulfur colloid labeled meal; normal saline or metoclopramide was administered before each test in a blinded and random manner. Half-time (T 1/2) and percentage of isotope remaining at six hours (GC6) were recorded. Ten asymptomatic controls had a gamma camera scanning study, and seven of these had a BTM. Nine of 19 patients had a T 1/2 in the normal range, and in 12 of 19 patients the GC6 was in the normal range. The magnitude of retention of barium at six hours on the BTM did not correlate with the T 1/2 (r = 0.076) or the GC6 (r = 0.296). Thus, these tests were not comparable in this study. By regression analysis, a significant reduction was shown in the amount of retained food and barium (P < .01), the T 1/2 (P < .01), and the GC6 (P < .01) after intramuscular administration of metoclopramide, indicating that both tests were able to evaluate the effects of this drug.

  12. Comparison of the barium test meal and the gamma camera scanning technic in measuring gastric emptying

    Perkel, M.S.; Fajman, W.A.; Hersh, T.; Moore, C.; Davidson, E.D.; Haun, C.

    1981-09-01

    In 21 patients with nonresected stomachs and symptoms of delayed gastric emptying, obstruction was excluded by upper gastrointestinal series and upper endoscopy; all had abnormal results of barium test meal (BTM) study. Each had repeat BTM after the administration of 10 mg of metoclopramide. Each patient also had two gamma camera studies after a technetium Tc 99m sulfur colloid labeled meal; normal saline or metoclopramide was administered before each test in a blinded and random manner. Half-time (T1/2) and percentage of isotope remaining at six hours (GC6) were recorded. Ten asymptomatic controls had a gamma camera scanning study, and seven of these had a BTM. Nine of 19 patients had a T1/2 in the normal range, and in 12 of 19 patients the GC6 was in the normal range. The magnitude of retention of barium at six hours on the BTM did not correlate with the T1/2 (r . 0.076) or the GC6 (r. 0.296). Thus, these tests were not comparable in this study. By regression analysis, a significant reduction was shown in the amount of retained food and barium (P less than .01), the T1/2 (P less than .01), and the GC6 (P less than .01) after intramuscular administration of metoclopramide, indicating that both tests were able to evaluate the effects of this drug.

  13. Performances evaluation of the coincidence detection on a gamma-camera

    Dreuille, O. de; Gaillard, J.F.; Brasse, D.; Bendriem, B.; Groiselle, C.; Rocchisani, J.M.; Moretti, J.L.

    2000-01-01

    The performance of the VERTEX gamma-camera (ADAC) working in coincidence mode are investigated using a protocol derived from the NEMA and IEC recommendations. With a field of view determined by two rectangular detectors (50.8 cm x 40 cm) composed of NaI crystal, this camera allows a 3-D acquisition with different energy window configurations: photopeak-photopeak only (PP) and photopeak-photopeak + photopeak-Compton (PC). An energy resolution of 11% and a scatter fraction of 27% and 33% for the 3D-PP and 3D-PC mode respectively are the main significant results of our study. The spatial resolution equals 5.9 mm and the limit of the detectability ranges from 16 mm to 13 mm for a contrast of 2.5: as a function of the random estimation, the maximum of the Noise Equivalent Count rate varies from 3 kcps to 4.5 kcps for the PP mode and from 3.85 kcps to 6.1 kcps for the PC mode. These maxima are reached for a concentration of 8 kBq/ml for the PP mode and 5 kBq/ml for the PC mode. These values are compared with the results obtained by other groups for the VERTEX gamma camera and several dedicated PET systems. (authors)

  14. Expanding of FOV of NaI(Tl) gamma camera detectors-Is it possible?

    Gayshan, Vadim L.; Gektin, A.V.; Boyarintsev, A.; Pedash, V.

    2006-01-01

    Every gamma camera detector used for medical imaging of conventional design faces the problem of distorted or no information readout at the areas closer to the edge of detectors. Obtaining position and energy information becomes almost impossible at distance 0-12 of PMT size from the edge. Therefore, in some designs were proposed losing of edge energy resolution while improving in spatial uniformity when it comes to imaging at the edges. This work is dedicated to understanding of the problem, mathematical simulations, practical tests and recommendations to build detectors with larger usable FOV without increasing in dimensions. To study the problem we built the test jig with linear motion source and readout electronics to simulate gamma cameras of PMTs. Based on simulation results the idea of modifying of crystal shape combined with specific light redirection system of baffles was tested and allowed to expand usable FOV. The results are presented and showed that for traditional NaI(Tl) scintillators using 2'' PMT may be possible to obtain relatively good spatial resolution starting from 4-5mm from the edge of a detector. The question of economical efficiency of proposed method is being investigated and a special detector manufacturing technology must be developed to accommodate this. While we believe that achieved results are very important for small size detectors (<20cm) they could be beneficial even for larger detectors used in whole body imaging systems

  15. Performance evaluation of a hand-held, semiconductor (CdZnTe)-based gamma camera

    Abe, A; Lee, J; Oka, T; Shizukuishi, K; Kikuchi, T; Inoue, T; Jimbo, M; Ryuo, H; Bickel, C

    2003-01-01

    We have designed and developed a small field of view gamma camera, the eZ SCOPE, based on use of a CdZnTe semiconductor. This device utilises proprietary signal processing technology and an interface to a computer-based imaging system. The purpose of this study was to evaluate the performance of the eZ scope in comparison with currently employed gamma camera technology. The detector is a single wafer of 5-mm-thick CdZnTe that is divided into a 16 x 16 array (256 pixels). The sensitive area of the detector is a square of dimension 3.2 cm. Two parallel-hole collimators are provided with the system and have a matching (256 hole) pattern to the CdZnTe detector array: a low-energy, high-resolution parallel-hole (LEHR) collimator fabricated of lead and a low-energy, high-sensitivity parallel-hole (LEHS) collimator fabricated of tungsten. Performance measurements and the data analysis were done according to the procedures of the NEMA standard. We also studied the long-term stability of the system with continuous use...

  16. Values of tumor markers (AFP, β-HCG and CEA) and gamma-camera scintigraphy in patients with testicular tumors

    Milkov, V.; Sultanov, S.; Tsvetkov, D.

    1989-01-01

    Complex gamma-camera and radioimmunologic study of the tumor markers AFP, β-HCG and CEA was performed in 7 patients with testicular tumors. In all tested patients gamma-camera scintigraphy of the testes clearly delineated the zone of the pathological process. Gamma-camera examination very well differentiates malignant from nonmalignant processes in the testes. The serum levels of the tumor markers AFP and β-HCG proved elevated in 3 of the tested patients during the preoperative period. The histological types of the tumors in these patients were: teratocarcinoma in one and embryonal carcinoma in the other two. It is believed that investigation of the three tumor markers may gain acceptance as additonal method in the complex diagnosis of these diseases

  17. The implementation of quality controls of gamma camera functioning and simulation of tomography techniques by Gate and GEANT4

    Ben Ameur, Narjes

    2011-01-01

    The reliability of medical devices is directly linked to the services quality offered to the patient. For this reason, quality control tests should be regularly conducted in every nuclear medicine service according to international norms. Our approach consists on realizing different quality control tests recommended by the Nema norm on a gamma-camera in order to evaluate its performance. The obtained data allowed us to study the different physical phenomena happening during a SPECT exam. It also allowed us to identify those affecting the image quality based on the simulation programmes: GEANT 4 and Gate. The obtained results of the quality control showed that the Gamma-camera has a high performance in terms of spatial resolution, linearity, uniformity and rotational center. The establishment of a model for a gamma-camera Symbia E (Siemens) using a Gate platform confirms the reliability of this platform in the conception and the optimization of the detectors.

  18. Three-layer GSO depth-of-interaction detector for high-energy gamma camera

    Yamamoto, S.; Watabe, H.; Kawachi, N.; Fujimaki, S.; Kato, K.; Hatazawa, J.

    2014-01-01

    Using Ce-doped Gd 2 SiO 5 (GSO) of different Ce concentrations, three-layer DOI block detectors were developed to reduce the parallax error at the edges of a pinhole gamma camera for high-energy gamma photons. GSOs with Ce concentrations of 1.5 mol% (decay time ∼40 ns), 0.5 mol% crystal (∼60 ns), 0.4 mol% (∼80 ns) were selected for the depth of interaction (DOI) detectors. These three types of GSOs were optically coupled in the depth direction, arranged in a 22×22 matrix and coupled to a flat panel photomultiplier tube (FP-PMT, Hamamatsu H8500). Sizes of these GSO cells were 1.9 mm×1.9 mm×4 mm, 1.9 mm×1.9 mm×5 mm, and 1.9 mm×1.9 mm×6 mm for 1.5 mol%, 0.5 mol%, and 0.4 mol%, respectively. With these combinations of GSOs, all spots corresponding to GSO cells were clearly resolved in the position histogram. Pulse shape spectra showed three peaks for these three decay times of GSOs. The block detector was contained in a 2-cm-thick tungsten shield, and a pinhole collimator with a 0.5-mm aperture was mounted. With pulse shape discrimination, we separated the point source images of the Cs-137 for each DOI layer. The point source image of the lower layer was detected at the most central part of the field-of-view, and the distribution was the smallest. The point source image of the higher layer was detected at the most peripheral part of the field-of-view, and the distribution was widest. With this information, the spatial resolution of the pinhole gamma camera can be improved. We conclude that DOI detection is effective for pinhole gamma cameras for high energy gamma photons

  19. Integration of gamma cameras and PET devices of multiple vendors in several locations

    Dresel, S.; Vollmar, C.; Sengupta, S.; Hahn, K.

    2002-01-01

    Full text: The Department of Nuclear Medicine of the University of Munich consists of four independently operated locations with a total of 18 gamma cameras (of three vendors), one PET scanner and one coincidence gamma camera. Recent hardware improvements, the installation and development of fast networks and new technologies for storage of large data volumes all contribute to the propagation of digital reading and reporting of nuclear medicine studies. Thus, the vision of a fully digitized nuclear medicine department becomes reality. In 1997 the department started with a strategy to fully integrate the entire number of imaging devices into one network for filmless reading, archiving and distributing nuclear medicine studies throughout the hospitals. The decision was made to use HERMES workstations (Nuclear Diagnostics, Sweden) to connect all primary imaging modalities. The purpose of the workstations located in the Nuclear Medicine departments is threefold: postprocessing, reading and archiving of all data. The workstations are networked throughout the different hospitals and are able to read the proprietary or DICOM data of the vendors of the gamma camera and PET equipment. The HERMES system is connected via DICOM interface to a long term storage device (AGFA, Germany). Additionally a JAVA (SUN Microsystems, USA) based software (JARVIS, Nuclear Diagnostics) is available to view all data from any computer using a web browser. Furthermore all data is linked to the hospital information system and selected imaging data are distributed throughout the hospitals. After commencement of full service of the network in 2000 the department is over 95 % filmfree. The high costs of purchasing hardware- and software-components are compensated for by saving costs of films and by the improvement of the work flow. Independently from these issues, filmless reporting proves to be advantageous over conventional film reading in many facts that justify to switch to a digital department

  20. SiPM-MAROC gamma-camera prototype with monolithic NaI(Tl) scintillator

    Philippov, Dmitry; Ilyin, Andrey; Belyaev, Vladimir; Popova, Elan [National Research Nuclear University, Moscow Engineering Physics Institute (Russian Federation); Buzhan, Pavel; Stifutkin, Alexei [Moscow Engineering Physics Institute (Russian Federation)

    2015-05-18

    A full-body gamma-camera based on SiPM readout is currently under development as a part of MEPHI R activity supported in the framework of Russian Megagrants program. A goal of this development is a fast upgrade of existing medical equipment with minor changes in a system design and construction in order to combine SPECT and MR instruments. A monolithic NaI(Tl) scintillator commonly used for conventional PMT-based gamma cameras has been chosen for this study. SiPMs will be coupled with the scintillator via an optical guide. To cover scintillator surface thousands of SiPMs are required, together with multichannel front-end electronics. That means that readout electronics have to be very compact, with low power consumption and low cost. 64 – channel ASIC MAROC from Weeroc provides individual readout of each SiPM and has been considered as the best choice among electronics solutions available on the market. As the photodetector parameters are the key issues here, KETEK SiPMs with high detection efficiency, low crosstalk and low noise have been chosen for this study. In order to study the proposed detection system in detail and obtain detector module parameters, required for MC simulation, a 64-channel small prototype with 6x6mm{sup 2} SiPMs has been constructed and tested. SiPMs in SMD packages have been assembled as a matrix of 8x8 elements and readout by MAROC-based board. Prototype has been tested with different shape NaI(Tl) scintillators and gammas with different energy. Dedicated algorithms for extraction of gamma-event’s energy and position are under development. They are based on fitting a matrix of individual SiPMs responses by an analytical function F(x,y). They will be tested with GEANT-simulated events and experimental data. Development of the next (engineering) prototype of SiPM’s module for gamma-camera will be started soon.

  1. SiPM-MAROC gamma-camera prototype with monolithic NaI(Tl) scintillator

    Philippov, Dmitry; Ilyin, Andrey; Belyaev, Vladimir; Popova, Elan; Buzhan, Pavel; Stifutkin, Alexei

    2015-01-01

    A full-body gamma-camera based on SiPM readout is currently under development as a part of MEPHI R activity supported in the framework of Russian Megagrants program. A goal of this development is a fast upgrade of existing medical equipment with minor changes in a system design and construction in order to combine SPECT and MR instruments. A monolithic NaI(Tl) scintillator commonly used for conventional PMT-based gamma cameras has been chosen for this study. SiPMs will be coupled with the scintillator via an optical guide. To cover scintillator surface thousands of SiPMs are required, together with multichannel front-end electronics. That means that readout electronics have to be very compact, with low power consumption and low cost. 64 – channel ASIC MAROC from Weeroc provides individual readout of each SiPM and has been considered as the best choice among electronics solutions available on the market. As the photodetector parameters are the key issues here, KETEK SiPMs with high detection efficiency, low crosstalk and low noise have been chosen for this study. In order to study the proposed detection system in detail and obtain detector module parameters, required for MC simulation, a 64-channel small prototype with 6x6mm 2 SiPMs has been constructed and tested. SiPMs in SMD packages have been assembled as a matrix of 8x8 elements and readout by MAROC-based board. Prototype has been tested with different shape NaI(Tl) scintillators and gammas with different energy. Dedicated algorithms for extraction of gamma-event’s energy and position are under development. They are based on fitting a matrix of individual SiPMs responses by an analytical function F(x,y). They will be tested with GEANT-simulated events and experimental data. Development of the next (engineering) prototype of SiPM’s module for gamma-camera will be started soon.

  2. Germanium soup

    Palmer, Troy A.; Alexay, Christopher C.

    2006-05-01

    This paper addresses the variety and impact of dispersive model variations for infrared materials and, in particular, the level to which certain optical designs are affected by this potential variation in germanium. This work offers a method for anticipating and/or minimizing the pitfalls such potential model variations may have on a candidate optical design.

  3. A new collimator for measurement of rCBF by means of gamma camera

    Zechmann, W.; Oberladstaetter, M.; Raccabona, G.; Vogl, G.; Gerstenbrand, F.

    1982-01-01

    Atraumatic measurement of rCBF by means of gamma camera and conventional collimators requires high doses of 133 Xenon to obtain high count rates over the cerebral ROI's. The input of time-activity curve of breathing air by means of a probe measurement is not possible on line without difficulties. A new collimator, developed by ours, which is comparable with standard rCBF-Multiprobe systems, which allows high countrates and low dose of 133 Xenon is presented. A special air bypass enables to get the breathing curve with simple ROI technique. The collimator can easily be adapted to the camera by means of an insert adapter ring. With this collimator the rCBF measurement with conventional equipment of a nuclear medicine department is possible. (Author)

  4. Renal scintiscanning: Methodology and normal findings using 131I hippurane and a gamma camera

    Ruppik, G.

    1982-01-01

    The methodological and mathematical fundamentals of renal functional scintiscanning using a gamma camera and 131 I-hippurane are described for ING, whole-body clearance, plasma clearance, and unilateral clearance. Methods are compared introducing the Tuebingen method of unilateral clearance with tolerance limits. The data of the patients are presented as standard values with a limit of two standard deviations for whole-body clearance unilateral clearance, the parenchymal phase and the excretion phase including a percentage of excretion. Comparative studies are presented for the main parameters of clearance and unilateral clearance, and the data obtained are documented in tables and graphs together with the initial data and the standard values. The results and problems of the method are gone into. (orig./MG) [de

  5. Risks assessment associated with the use of an analyzer for gamma cameras diagnostic

    Oramas Polo, I.; Figueroa del Valle, D. G.

    2013-01-01

    Technological development experienced by the industrialized countries has been accompanied by a significant improvement in living standards. Likewise, the proliferation of facilities and transportation of certain materials have involved the emergence of new risks, which could cause accidents with a strong impact on people and the environment. The paper makes a risk assessment associated with the use of an analyzer for Gamma Cameras diagnostic. The method is bases on determining the number of risks HRN (Hazard Rating Number). As a result of the methodology used was obtained the risks that have more implications in the use of this system and sets safety rules for their use and an action plan for managing them. (Author)

  6. Single-acquisition method for simultaneous determination of extrinsic gamma-camera sensitivity and spatial resolution

    Santos, J.A.M. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)], E-mail: a.miranda@portugalmail.pt; Sarmento, S. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Alves, P.; Torres, M.C. [Departamento de Fisica da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Bastos, A.L. [Servico de Medicina Nuclear, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Ponte, F. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)

    2008-01-15

    A new method for measuring simultaneously both the extrinsic sensitivity and spatial resolution of a gamma-camera in a single planar acquisition was implemented. A dual-purpose phantom (SR phantom; sensitivity/resolution) was developed, tested and the results compared with other conventional methods used for separate determination of these two important image quality parameters. The SR phantom yielded reproducible and accurate results, allowing an immediate visual inspection of the spatial resolution as well as the quantitative determination of the contrast for six different spatial frequencies. It also proved to be useful in the estimation of the modulation transfer function (MTF) of the image formation collimator/detector system at six different frequencies and can be used to estimate the spatial resolution as function of the direction relative to the digital matrix of the detector.

  7. Single-acquisition method for simultaneous determination of extrinsic gamma-camera sensitivity and spatial resolution

    Santos, J.A.M.; Sarmento, S.; Alves, P.; Torres, M.C.; Bastos, A.L.; Ponte, F.

    2008-01-01

    A new method for measuring simultaneously both the extrinsic sensitivity and spatial resolution of a gamma-camera in a single planar acquisition was implemented. A dual-purpose phantom (SR phantom; sensitivity/resolution) was developed, tested and the results compared with other conventional methods used for separate determination of these two important image quality parameters. The SR phantom yielded reproducible and accurate results, allowing an immediate visual inspection of the spatial resolution as well as the quantitative determination of the contrast for six different spatial frequencies. It also proved to be useful in the estimation of the modulation transfer function (MTF) of the image formation collimator/detector system at six different frequencies and can be used to estimate the spatial resolution as function of the direction relative to the digital matrix of the detector

  8. Risk analysis for working with an analyzer for gamma cameras diagnostic

    Oramas Polo, Ivon; Figueroa del Valle, Diana G.

    2014-01-01

    In this work, an analysis of the risks for working with an analyzer for gamma cameras diagnostic was made. The method employed is based on determining the Hazard Rating Number (HRN). The results showed that the risks with higher value of HRN are electrocution with 100 and touch source container with hands with 75. These risks were classified as 'Very High' and 'High' respectively. The following risks were classified as 'Important': Fall of the source container (HRN = 25), high dose of the sample in the container (HRN = 20) and fracture of glass detector (HRN = 30). The wrong shielding of the source container (HRN = 10) is a risk that was classified as L ow . Safety rules for use of the system are indicated. An action plan for risk management is also presented. (author)

  9. A new approach to the evaluation of peripheral vascular disease using the gamma camera

    Gerritsen, H.A.M.

    1976-01-01

    To estimate the degree of impaired perfusion in legs, and the extent of improvement after treatment, a functional test was developed using a gamma camera to follow the perfusion of intravenously injected sup(99m)Tc-pertechnetate. An analysis is given of normal and pathologic curve patterns. The influence of the severity of occlusive arterial disease on the arrival and distribution of radioactivity in the leg is demonstrated. After vascular surgery, changes in the curve pattern and the imaging of activity distribution reflected the function of the inserted bypass grafts. The test proved to be useful in the differentiation between patients with false claudication complaints due to non-arterial disease and patients with true claudication. It is concluded that the technique presented in this thesis can serve as a useful, non-invasive, screening test prior to arteriography and as a functional assessment of vascular reconstruction

  10. A versatile calibration procedure for portable coded aperture gamma cameras and RGB-D sensors

    Paradiso, V.; Crivellaro, A.; Amgarou, K.; de Lanaute, N. Blanc; Fua, P.; Liénard, E.

    2018-04-01

    The present paper proposes a versatile procedure for the geometrical calibration of coded aperture gamma cameras and RGB-D depth sensors, using only one radioactive point source and a simple experimental set-up. Calibration data is then used for accurately aligning radiation images retrieved by means of the γ-camera with the respective depth images computed with the RGB-D sensor. The system resulting from such a combination is thus able to retrieve, automatically, the distance of radioactive hotspots by means of pixel-wise mapping between gamma and depth images. This procedure is of great interest for a wide number of applications, ranging from precise automatic estimation of the shape and distance of radioactive objects to Augmented Reality systems. Incidentally, the corresponding results validated the choice of a perspective design model for a coded aperture γ-camera.

  11. Measurement of spleen size using gamma camera scintigraphy in essential thrombocythaemia

    Revesz, P. (Department of Medicine, Oestra Hospital, University of Goeteborg, Goeteborg (Sweden)); Carneskog, J.; Wadenvik, H.; Kutti, J. (Haematology Section, Department of Medicine, Sahlgrenska Hospital, University of Goeteborg, Goeteborg (Sweden)); Jarneborn, L. (Department of Clinical Physiology, Oestra Hospital, University of Goeteborg, Goeteborg (Sweden))

    1993-09-01

    By using gamma camera imaging the spleen size was determined in 33 consecutive patients with essential thrombocythaemia (ET) and in 33 consecutive patients with reactive thrombocytosis (RT). All ET patients were newly diagnosed and had not received myelosuppressive treatment prior to study; they all fulfilled the criteria for ET as established by the Polycythemia Vera Study Group. In both posterior and lateral projections, the spleen area in the group of ET patients was significantly larger than in the RT patients. The present study has shown that 39% of ET patients at diagnosis have splenic enlargement. Evaluation of Spleen size is therefore a useful diagnostic test in patients presenting with unexplained thrombocytosis. (au) (15 refs.).

  12. PET with coincidence gamma cameras - clinical benefit from the radiooncologists' point of view

    Richter, E.; Feyerabend, T.; Stallmann, C.; Lauer, I.; Baehre, M.

    2001-01-01

    Positron emission tomography with FDG (FDG-PET) is a new technique, which displays the cellular metabolic activity. Since tumors exhibit an increased metabolic activity when compared to normal tissue, this imaging modality has a particularly high importance. FDG-PET is not only useful for localizing and staging of malignant tumors, but also to evaluate therapy response. In this context, PET is superior to morphologically orientated modalities, because therapeutically induced changes in glucose metabolism precede morphologic alterations. Numerous studies indicate, that PET will play an important role in radiooncology concerning therapy planning and monitoring the effects of therapy during and after treatment. Further clinical studies are necessary to evaluate the information provided by FDG-PET more precisely. Coincidence gamma cameras with adequate imaging characteristics will gain enhanced importance to meet these increasing demands. (orig.) [de

  13. Gastric emptying time in normal subjects using /sup 51/Cr and a gamma camera

    Claure, H [Hospital del Salvador, Santiago de Chile; Calderon, C; Braunschweig, T; Diaz, G

    1974-12-01

    Gastric emptying time of a meal consisting of 2 eggs, 50 g of white bread, and 300 ml of milk, was measured in 10 normal subjects, 5 males and 5 females, with an average age of 34.7 years. 200 uCi of Cr-51 were added to the meal and external counting was performed using a ..gamma.. camera. The rate of gastric emptying was estimated by the decrease in radiation counts over the gastric area. In 68.6 percent of the subjects the mean gastric emptying time was 60 min. The average curve showed a complex exponential slope with 2 distinct phases: a fast one between 0 and 35 min and a slow one between 40 and 60 min. These results suggest that a normal gastric emptying time consists of 2 different rate phases when a meal of mixed consistency (liquid and solid) is ingested.

  14. Applications of multi-pinhole gamma camera collimation to tomography and image enhancement

    Simpson, D. R.

    1981-06-01

    Multi-pinhole gamma camera collimation was introduced in the field of emission tomography. This collimation process simultaneously produces several images covering a limited angular range, which may then be recombined to obtain tomographic slices of the object imaged. A possible method for improving the images obtained by this technique by combining two multi-pinhole views taken 90 deg apart was investigated. Collimators were designed and built both for tomography and imaging tablet disintegration, and computer programs were written to reconstruct the images by simple backprojection and by filtered backprojection. The use of multi-pinhole collimators to image the disintegration of tablets in vivo was clearly demonstrated. Phantom tests done in vitro were capable of imaging defects as small as 5 sq mm, while images made with real tablets both in vitro and in vivo readily showed the onset and progress of the tablet disintegration.

  15. A study of quantitative scale display of the organ uptake with gamma-camera

    Ishigami, K; Matsumoto, M [Kumamoto Univ. (Japan) School of Medicine

    1975-05-01

    The fundamental study of quantitative scale display of the organ uptake with ..gamma..-camera was performed in special respect of the thyroid gland and the pancreas. As one of the measurements on certain dimension of the organ, an optical progression outside the digital image was expressed, and was subjected to the quantitative scale with the use of the threshold level. And a rather satisfactory correlation was clinically obtained between the scale display and the thyroidal /sup 131/I uptake. For the purpose of revising the above scale display, the organ depth was measured with RI by the aid of the phantom. Then the pancreas depth determined by the count rate ratio curve of 140 and 270 keV peak of /sup 75/Se energies. However, the body background and the radioactive rays from the neighboring organs interfered with this curve.

  16. Corrosion of high purity Fe-Cr-Ni alloys in 13 N boiling nitric acid

    Ohta, Joji; Mayuzumi, Masami; Kusanagi, Hideo; Takaku, Hiroshi

    1998-01-01

    Corrosion in boiling nitric acid was investigated for high purity Fe-18%Cr-12%Ni alloys and type 304L stainless steels (SS). Owing to very low impurity concentration, the solution treated high purity alloys show almost no intergranular corrosion while the type 304L SS show severe intergranular corrosion. Both in the high purity alloys and type 304L SS, aging treatments ranging from 873 K to 1073 K for 1 h enhance intergranular corrosion. During the aging treatments, impurities should be segregated to the grain boundaries. The corrosion behaviors were discussed from a standpoint of impurity segregation to grain boundaries. This study is of importance for purex reprocessing of spent fuels

  17. Two-dimensional diced scintillator array for innovative, fine-resolution gamma camera

    Fujita, T.; Kataoka, J.; Nishiyama, T.; Ohsuka, S.; Nakamura, S.; Yamamoto, S.

    2014-01-01

    We are developing a technique to fabricate fine spatial resolution (FWHM<0.5mm) and cost-effective photon counting detectors, by using silicon photomultipliers (SiPMs) coupled with a finely pixelated scintillator plate. Unlike traditional X-ray imagers that use a micro-columnar CsI(Tl) plate, we can pixelate various scintillation crystal plates more than 1 mm thick, and easily develop large-area, fine-pitch scintillator arrays with high precision. Coupling a fine pitch scintillator array with a SiPM array results in a compact, fast-response detector that is ideal for X-ray, gamma-ray, and charged particle detection as used in autoradiography, gamma cameras, and photon counting CTs. As the first step, we fabricated a 2-D, cerium-doped Gd 3 Al 2 Ga 3 O 12 (Ce:GAGG) scintillator array of 0.25 mm pitch, by using a dicing saw to cut micro-grooves 50μm wide into a 1.0 mm thick Ce:GAGG plate. The scintillator plate is optically coupled with a 3.0×3.0mm pixel 4×4 SiPM array and read-out via the resistive charge-division network. Even when using this simple system as a gamma camera, we obtained excellent spatial resolution of 0.48 mm (FWHM) for 122 keV gamma-rays. We will present our plans to further improve the signal-to-noise ratio in the image, and also discuss a variety of possible applications in the near future

  18. Use of calibration methodology of gamma cameras for the workers surveillance using a thyroid simulator

    Alfaro, M.; Molina, G.; Vazquez, R.; Garcia, O.

    2010-09-01

    In Mexico there are a significant number of nuclear medicine centers in operation. For what the accidents risk related to the transport and manipulation of open sources used in nuclear medicine can exist. The National Institute of Nuclear Research (ININ) has as objective to establish a simple and feasible methodology for the workers surveillance related with the field of the nuclear medicine. This radiological surveillance can also be applied to the public in the event of a radiological accident. To achieve this it intends to use the available equipment s in the nuclear medicine centers, together with the neck-thyroid simulators elaborated by the ININ to calibrate the gamma cameras. The gamma cameras have among their component elements that conform spectrometric systems like the employees in the evaluation of the internal incorporation for direct measurements, reason why, besides their use for diagnostic for image, they can be calibrated with anthropomorphic simulators and also with punctual sources for the quantification of the radionuclides activity distributed homogeneously in the human body, or located in specific organs. Inside the project IAEA-ARCAL-RLA/9/049-LXXVIII -Procedures harmonization of internal dosimetry- where 9 countries intervened (Argentina, Brazil, Colombia, Cuba, Chile, Mexico, Peru, Uruguay and Spain). It was developed a protocol of cameras gamma calibration for the determination in vivo of radionuclides. The protocol is the base to establish and integrated network in Latin America to attend in response to emergencies, using nuclear medicine centers of public hospitals of the region. The objective is to achieve the appropriate radiological protection of the workers, essential for the sure and acceptable radiation use, the radioactive materials and the nuclear energy. (Author)

  19. FDG scan on an ordinary coincidence gamma camera (CDET) -preliminary data in pulmonary or colorectal cancer

    Montravers, F.; Grahek, D.; Ghazzar, N.; Younsi, N.; Kerrou, K.; Talbot, J.N. [Hopital Tenon, 75 - Paris (France). Services de Medecine Nucleaire; Wartski, M.; Zerbib, E. [Hopital Marie Lannelongue Le Plessis Robinson (France); Lumbroso, J. [Institut Gustave Roussy Villejuif (France)

    1997-12-31

    Full text. The purpose of this study to evaluate the impact of FDG scan performed on an ordinary CDET gamma camera on the therapeutic management of patients with pulmonary nodules or with suspicion of recurrent colorectal carcinoma. Methods: two tomoscintigrams (thorax and abdomen) were acquired, using a PICKER Prism XP 2000 coincidence gamma camera, 45 m after i.v. injection of 100-150 MBq of {sup 18} F-FDG in fasting patients. The 21 pts were explored in July or August 1997. Preliminary results: among 12 patients with pulmonary nodules, the planed surgery was replaced by chemotherapy after visualization of unknown metastases accumulating FDG in 3 patients. In another one, the high uptake of FDG by a lung nodule which has been known for 6 years, led to surgery and objectivation of an adenocarcinoma. In one case, the absence of FDG uptake corresponded to an abscess (true negative result). In the other 7 patients, the indication of surgery was confirmed but the procedure was modified in 2 cases. In case of suspicion of recurrent colorectal carcinoma (9 patients), the finding of a single focus of FDG uptake whereas CT scan was negative or inconclusive let do the decision of surgery in 3 patients. In one patient with pelvic pain without increase of tumor markers levels and with normal CT scan, a normal FDG scan confirmed the physician`s hypothesis of pain due to the previous therapy but do not recurrence. In one patient, the finding of 3 foci of uptake of FDG whereas CT scan was inconclusive confirmed the indication of chemotherapy. In 2 patients with FDG abdominal foci without morphologic abnormalities, the therapeutic strategy is not yet decided in 2 patients, no foci could be found. In conclusion, these preliminary results show that FDG scan has provided a help to the physician indecision-making for therapeutic strategy in 8 patients on 21 (38%) and a help to the surgeon in 2 more cases (48% as a whole)

  20. FDG scan on an ordinary coincidence gamma camera (CDET) -preliminary data in pulmonary or colorectal cancer

    Montravers, F.; Grahek, D.; Ghazzar, N.; Younsi, N.; Kerrou, K.; Talbot, J.N.; Lumbroso, J.

    1997-01-01

    Full text. The purpose of this study to evaluate the impact of FDG scan performed on an ordinary CDET gamma camera on the therapeutic management of patients with pulmonary nodules or with suspicion of recurrent colorectal carcinoma. Methods: two tomoscintigrams (thorax and abdomen) were acquired, using a PICKER Prism XP 2000 coincidence gamma camera, 45 m after i.v. injection of 100-150 MBq of 18 F-FDG in fasting patients. The 21 pts were explored in July or August 1997. Preliminary results: among 12 patients with pulmonary nodules, the planed surgery was replaced by chemotherapy after visualization of unknown metastases accumulating FDG in 3 patients. In another one, the high uptake of FDG by a lung nodule which has been known for 6 years, led to surgery and objectivation of an adenocarcinoma. In one case, the absence of FDG uptake corresponded to an abscess (true negative result). In the other 7 patients, the indication of surgery was confirmed but the procedure was modified in 2 cases. In case of suspicion of recurrent colorectal carcinoma (9 patients), the finding of a single focus of FDG uptake whereas CT scan was negative or inconclusive let do the decision of surgery in 3 patients. In one patient with pelvic pain without increase of tumor markers levels and with normal CT scan, a normal FDG scan confirmed the physician's hypothesis of pain due to the previous therapy but do not recurrence. In one patient, the finding of 3 foci of uptake of FDG whereas CT scan was inconclusive confirmed the indication of chemotherapy. In 2 patients with FDG abdominal foci without morphologic abnormalities, the therapeutic strategy is not yet decided in 2 patients, no foci could be found. In conclusion, these preliminary results show that FDG scan has provided a help to the physician indecision-making for therapeutic strategy in 8 patients on 21 (38%) and a help to the surgeon in 2 more cases (48% as a whole)

  1. Evaluation of different physical parameters that affect the clinical image quality for gamma camera by using different radionuclides

    Salah, F.A.; Ziada, G.; Hejazy, M.A.; Khalil, W.A.

    2008-01-01

    Some scintillation camera manufactures adhere to standard code of performance specification established by National Electric Manufactures Association (NEMA). Items such as differential and integral uniformity, spatial resolution energy resolution, etc. are all calculated with reproducible methodology that allows the user reliable technique for creation of these standards to avoid any lack of clinical service that may violate the ethics of patient care. Because 99m Tc is the most frequently used radionuclide in nuclear medicine, many clinics perform the daily uniformity and weekly resolution checks using this radionuclide. But when other commonly used radionuclide such as Tl-201,Ga-67 and I-131 are used, no standardized quality control is performed. So in these study we perform to evaluate the response of ADAC(digital) gamma camera and SELO(analogue) gamma camera to four radionuclide (Tl-201,Ga-67, I-131, and 99m Tc) flood image acquired using different non-uniformity correction tables. In the planer study uniformity and resolution images were obtained using ADAC and SELO cameras, linearity was obtained only by ADAC camera, while in the SPECT study uniformity and contrast images were obtained using ADAC camera only. The response for using different non-uniformity correction tables acquired using different isotopes was different from gamma camera model to another. We can conclude that the most of the gamma camera quality control parameters (uniformity, resolution and contrast) are influenced by variation in the correction tables, while other parameters not affected by this variation like linearity. (author)

  2. Nema tests in gamma-cameras. Independent implementation of manufacturer; Pruebas Nema en gammacamaras. Implementacion independiente del fabricante

    Ramos Pacho, J. A.; Montes Fuentes, C.; Verde Velasco, J. M.; Perez Alvarez, M. E.; Delgado Aparicio, J. M.; Cons Perez, N.; Gomez Gonzalez, N.; Garcia Repiso, S.; Saez Beltran, M.; Gomez Llorente, P. L.

    2013-07-01

    The analysis of test results of quality control in gamma cameras, as extrinsic planar uniformity and the spatial resolution is often limited by intrinsic equipment tools and procedures. With the objective of an independent assessment of such evidence and better management and monitoring of the data obtained are made two separate programs in Matlab. (Author)

  3. Small Field of View Scintimammography Gamma Camera Integrated to a Stereotactic Core Biopsy Digital X-ray System

    Andrew Weisenberger; Fernando Barbosa; T. D. Green; R. Hoefer; Cynthia Keppel; Brian Kross; Stanislaw Majewski; Vladimir Popov; Randolph Wojcik

    2002-10-01

    A small field of view gamma camera has been developed for integration with a commercial stereotactic core biopsy system. The goal is to develop and implement a dual-modality imaging system utilizing scintimammography and digital radiography to evaluate the reliability of scintimammography in predicting the malignancy of suspected breast lesions from conventional X-ray mammography. The scintimammography gamma camera is a custom-built mini gamma camera with an active area of 5.3 cm /spl times/ 5.3 cm and is based on a 2 /spl times/ 2 array of Hamamatsu R7600-C8 position-sensitive photomultiplier tubes. The spatial resolution of the gamma camera at the collimator surface is < 4 mm full-width at half-maximum and a sensitivity of /spl sim/ 4000 Hz/mCi. The system is also capable of acquiring dynamic scintimammographic data to allow for dynamic uptake studies. Sample images of preliminary clinical results are presented to demonstrate the performance of the system.

  4. Void swelling in fast reactor irradiated high purity binary iron-chromium alloys

    Little, E.A.; Stow, D.A.

    The void swelling characteristics of a series of high purity binary iron-chromium alloys containing 0 - 615 0 C. The void swelling behaviour can be qualitatively rationalized in terms of point defect trapping and precipitation processes involving chromium atoms

  5. Confined recrystallization of high-purity aluminium during accumulative roll bonding of aluminium laminates

    Chekhonin, Paul; Beausir, Benoît; Scharnweber, Juliane; Oertel, Carl-Georg; Hausöl, Tina; Höppel, Heinz Werner; Brokmeier, Heinz-Günter; Skrotzki, Werner

    2012-01-01

    Aluminium laminates consisting of high-purity aluminium and commercially pure aluminium have been produced by accumulative roll bonding (ARB) at ambient temperature for up to 10 cycles. To study the microstructure and texture development of the high-purity aluminium layers with regard to the shrinking layer thickness during ARB, microstructure and texture investigations were carried out by electron backscatter diffraction and neutron and X-ray diffraction, respectively. While the commercially pure aluminium layers develop an ultrafine-grained microstructure, partial discontinuous recrystallization occurs in the high-purity layers. The texture of the high-purity layers mainly consists of Cube and “Tilted Cube” (tilted with respect to the transverse direction) components. The experimental results are discussed with respect to confined recrystallization in the ARB aluminium laminates.

  6. Array of germanium detectors for nuclear safeguards

    Moss, C.E.; Bernard, W.; Dowdy, E.J.; Garcia, C.; Lucas, M.C.; Pratt, J.C.

    1983-01-01

    Our gamma-ray spectrometer system, designed for field use, offers high efficiency and high resolution for safeguards applications. The system consists of three 40% high-purity germanium detectors and a LeCroy 3500 data-acquisition system that calculates a composite spectrum for the three detectors. The LeCroy 3500 mainframe can be operated remotely from the detector array with control exercised through moderns and the telephone system. System performance with a mixed source of 125 Sb, 154 Eu, and 155 Eu confirms the expected efficiency of 120% with an overall resolution that is between the resolution of the best detector and that of the worst

  7. Analysis technique of impurity in high purity deuterium by cryogenic gas-chromatography

    Zhou Junbo; Gao Liping

    2007-01-01

    A veracious and applicable quantitative analysis method of O 2 , N 2 and H 2 , HD in high purity deuterium by the chromatogram columniation filled with 5A molecular sieve and alumina was researched and constituted at natural temperature and 77 K, respectively. Minimum detecting limit of the present method is (150-200) x 10 -6 for H 2 and HD, and it can meet the need of quantitative analysis of the impurity during high purity deuterium preparation. (authors)

  8. Intraoperative radioguidance with a portable gamma camera: a novel technique for laparoscopic sentinel node localisation in urological malignancies

    Vermeeren, L.; Valdes Olmos, R.A.; Vogel, W.V.; Sivro, F.; Hoefnagel, C.A.; Meinhardt, W.; Bex, A.; Poel, H.G. van der; Horenblas, S.

    2009-01-01

    Our aim was to assess the feasibility of intraoperative radioguidance with a portable gamma camera during laparoscopic sentinel node (SN) procedures in urological malignancies. We evaluated the use of the intraoperative portable gamma camera in 20 patients: 16 patients with prostate carcinoma (PCC), 2 patients with renal cell carcinoma (RC) and 2 patients with testicular cancer (TC). Intra/peritumoural injection of 99m Tc-nanocolloid ( 99m Tc) was followed by planar lymphoscintigraphy, SPECT/CT and marking of SN levels. Before laparoscopy a 125 I seed was fixed on the laparoscopic gamma probe as a pointer of SN seeking. The portable gamma camera was set to display the 99m Tc signal for SN localisation and the 125 I signal for SN seeking. Matching of these signals on screen indicated exact SN localisation, and consequently this SN was removed. The mean injected dose was 218 MBq in PCC, 228 MBq in RC and 88 MBq in TC. Pelvic SN were visualised in all PCC patients, with uncommonly located SN in seven patients. SN metastases were found in seven patients (one in a uncommonly located SN). Both RC patients and TC patients had para-aortic SN, which were all tumour free. A total of 59 SN were removed. The portable gamma camera enabled real-time SN display/identification in 18 patients (90%). The use of a portable gamma camera in combination with a laparoscopic gamma probe incorporates intraoperative real-time imaging with improved SN identification in urological malignancies. This procedure might also be useful for SN identification of other deep draining malignancies. (orig.)

  9. Intraoperative radioguidance with a portable gamma camera: a novel technique for laparoscopic sentinel node localisation in urological malignancies

    Vermeeren, L.; Valdes Olmos, R.A.; Vogel, W.V.; Sivro, F.; Hoefnagel, C.A. [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Department of Nuclear Medicine, Amsterdam (Netherlands); Meinhardt, W.; Bex, A.; Poel, H.G. van der; Horenblas, S. [Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Department of Urology, Amsterdam (Netherlands)

    2009-07-15

    Our aim was to assess the feasibility of intraoperative radioguidance with a portable gamma camera during laparoscopic sentinel node (SN) procedures in urological malignancies. We evaluated the use of the intraoperative portable gamma camera in 20 patients: 16 patients with prostate carcinoma (PCC), 2 patients with renal cell carcinoma (RC) and 2 patients with testicular cancer (TC). Intra/peritumoural injection of {sup 99m}Tc-nanocolloid ({sup 99m}Tc) was followed by planar lymphoscintigraphy, SPECT/CT and marking of SN levels. Before laparoscopy a {sup 125}I seed was fixed on the laparoscopic gamma probe as a pointer of SN seeking. The portable gamma camera was set to display the {sup 99m}Tc signal for SN localisation and the {sup 125}I signal for SN seeking. Matching of these signals on screen indicated exact SN localisation, and consequently this SN was removed. The mean injected dose was 218 MBq in PCC, 228 MBq in RC and 88 MBq in TC. Pelvic SN were visualised in all PCC patients, with uncommonly located SN in seven patients. SN metastases were found in seven patients (one in a uncommonly located SN). Both RC patients and TC patients had para-aortic SN, which were all tumour free. A total of 59 SN were removed. The portable gamma camera enabled real-time SN display/identification in 18 patients (90%). The use of a portable gamma camera in combination with a laparoscopic gamma probe incorporates intraoperative real-time imaging with improved SN identification in urological malignancies. This procedure might also be useful for SN identification of other deep draining malignancies. (orig.)

  10. The germanium wall of the GEM detector system GEM Collaboration

    Betigeri, M.; Biakowski, E.; Bojowald, H.; Budzanowski, A.; Chatterjee, A.; Drochner, M.; Ernst, J.; Foertsch, S.; Freindl, L.; Frekers, D.; Garske, W.; Grewer, K.; Hamacher, A.; Igel, S.; Ilieva, J.; Jarczyk, L.; Jochmann, M.; Kemmerling, G.; Kilian, K.; Kliczewski, S.; Klimala, W.; Kolev, D.; Kutsarova, T.; Lieb, J.; Lippert, G.; Machner, H.; Magiera, A.; Nann, H.; Pentchev, L.; Plendl, H.S.; Protic, D.; Razen, B.; Rossen, P. von; Roy, B.J.; Siudak, R.; Smyrski, J.; Srikantiah, R.V.; Strzakowski, A.; Tsenov, R.; Zolnierczuk, P.A.; Zwoll, K.

    1999-01-01

    A stack of annular detectors made of high-purity germanium was developed. The detectors are position sensitive with radial structures. The first one ('Quirl') is double-sided position sensitive defining 40,000 pixels, the following three (E1, E2 and E3) have 32 wedges each. The Quirl acts as tracker while the other three act as calorimeter. The stack was successfully operated in meson production reactions close to threshold

  11. Study of a new architecture of gamma cameras with Cd/ZnTe/CdTe semiconductors; Etude d'une nouvelle architecture de gamma camera a base de semi-conducteurs CdZnTe /CdTe

    Guerin, L

    2007-11-15

    This thesis studies new semi conductors for gammas cameras in order to improve the quality of image in nuclear medicine. The chapter 1 reminds the general principle of the imaging gamma, by describing the radiotracers, the channel of detection and the types of Anger gamma cameras acquisition. The physiological, physical and technological limits of the camera are then highlighted, to better identify the needs of future gamma cameras. The chapter 2 is dedicated to a bibliographical study. At first, semi-conductors used in imaging gamma are presented, and more particularly semi-conductors CDTE and CdZnTe, by distinguishing planar detectors and monolithic pixelated detectors. Secondly, the classic collimators of the gamma cameras, used in clinical routine for the most part of between them, are described. Their geometry is presented, as well as their characteristics, their advantages and their inconveniences. The chapter 3 is dedicated to a state of art of the simulation codes dedicated to the medical imaging and the methods of reconstruction in imaging gamma. These states of art allow to introduce the software of simulation and the methods of reconstruction used within the framework of this thesis. The chapter 4 presents the new architecture of gamma camera proposed during this work of thesis. It is structured in three parts. The first part justifies the use of semiconducting detectors CdZnTe, in particular the monolithic pixelated detectors, by bringing to light their advantages with regard to the detection modules based on scintillator. The second part presents gamma cameras to base of detectors CdZnTe (prototypes or commercial products) and their associated collimators, as well as the interest of an association of detectors CdZnTe in the classic collimators. Finally, the third part presents in detail the HiSens architecture. The chapter 5 describes both software of simulation used within the framework of this thesis to estimate the performances of the Hi

  12. Cosmogenically-produced isotopes in natural and enriched high-purity germanium detectors for the MAJORANA DEMONSTRATOR

    Gilliss, Thomas; MAJORANA DEMONSTRATOR Collaboration

    2017-01-01

    The MAJORANA DEMONSTRATOR advances toward measurements of the neutrinoless double-beta decay of 76Ge. Detectors employed in the DEMONSTRATOR are subject to cosmogenic spallation during production and processing, resulting in activation of certain long-lived radioisotopes. Activation of these cosmogenic isotopes is mitigated by shielded storage of detectors and through underground operation of the DEMONSTRATOR at the 4850 ft level of the Sanford Underground Research Facility. In this work, we explore the appearance and reduction of cosmogenic contributions to the DEMONSTRATOR background spectrum. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

  13. Statistical pixelwise inference models for planar data analysis: an application to gamma-camera uniformity monitoring

    Kalemis, A [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Bailey, D L [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Flower, M A [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Lord, S K [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom); Ott, R J [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom)

    2004-07-21

    In this paper two tests based on statistical models are presented and used to assess, quantify and provide positional information of the existence of bias and/or variations between planar images acquired at different times but under similar conditions. In the first test a linear regression model is fitted to the data in a pixelwise fashion, using three mathematical operators. In the second test a comparison using z-scoring is used based on the assumption that Poisson statistics are valid. For both tests the underlying assumptions are as simple and few as possible. The results are presented as parametric maps of either the three operators or the z-score. The z-score maps can then be thresholded to show the parts of the images which demonstrate change. Three different thresholding methods (naive, adaptive and multiple) are presented: together they cover almost all the needs for separating the signal from the background in the z-score maps. Where the expected size of the signal is known or can be estimated, a spatial correction technique (referred to as the reef correction) can be applied. These tests were applied to flood images used for the quality control of gamma camera uniformity. Simulated data were used to check the validity of the methods. Real data were acquired from four different cameras from two different institutions using a variety of acquisition parameters. The regression model found the bias in all five simulated cases and it also found patterns of unstable regions in real data where visual inspection of the flood images did not show any problems. In comparison the z-map revealed the differences in the simulated images from as low as 1.8 standard deviations from the mean, corresponding to a differential uniformity of 2.2% over the central field of view. In all cases studied, the reef correction increased significantly the sensitivity of the method and in most cases the specificity as well. The two proposed tests can be used either separately or in

  14. Statistical pixelwise inference models for planar data analysis: an application to gamma-camera uniformity monitoring

    Kalemis, A; Bailey, D L; Flower, M A; Lord, S K; Ott, R J

    2004-01-01

    In this paper two tests based on statistical models are presented and used to assess, quantify and provide positional information of the existence of bias and/or variations between planar images acquired at different times but under similar conditions. In the first test a linear regression model is fitted to the data in a pixelwise fashion, using three mathematical operators. In the second test a comparison using z-scoring is used based on the assumption that Poisson statistics are valid. For both tests the underlying assumptions are as simple and few as possible. The results are presented as parametric maps of either the three operators or the z-score. The z-score maps can then be thresholded to show the parts of the images which demonstrate change. Three different thresholding methods (naive, adaptive and multiple) are presented: together they cover almost all the needs for separating the signal from the background in the z-score maps. Where the expected size of the signal is known or can be estimated, a spatial correction technique (referred to as the reef correction) can be applied. These tests were applied to flood images used for the quality control of gamma camera uniformity. Simulated data were used to check the validity of the methods. Real data were acquired from four different cameras from two different institutions using a variety of acquisition parameters. The regression model found the bias in all five simulated cases and it also found patterns of unstable regions in real data where visual inspection of the flood images did not show any problems. In comparison the z-map revealed the differences in the simulated images from as low as 1.8 standard deviations from the mean, corresponding to a differential uniformity of 2.2% over the central field of view. In all cases studied, the reef correction increased significantly the sensitivity of the method and in most cases the specificity as well. The two proposed tests can be used either separately or in

  15. Design and implementation of a quality assurance program for gamma cameras

    Montoya M, A.; Rodriguez L, A.; Trujillo Z, F. E.

    2010-09-01

    In nuclear medicine more than 90% of the carried out procedures are diagnostic. To assure an appropriate diagnostic quality of the images and the doses optimization received by the patients originated in the radioactive material, it is indispensable the periodic surveillance of the operation and performance of the equipment s by means of quality assurance tests. This work presents a proposal of a quality assurance program for gamma cameras based on recommendations of the IAEA, the American Association of Medical Physics and the National Electrical Manufacturers Association. Some tests of the program were applied to an e.cam gamma camera (Siemens) of the Nuclear Medicine Department of the National Institute of Cancer. The intrinsic and extrinsic uniformity, the intrinsic spatial resolution and the extrinsic sensibility were verified. For intrinsic uniformity the average daily values of the integral uniformity and differential uniformity in the useful vision field were 2.61% and 1.58% respectively, the average monthly values of intrinsic uniformity for the integral and differential uniformity in the useful vision field were 4.10% and 1.66% respectively. The used acceptance criterions were respectively of 3.74% and 2.74%. The average values of extrinsic uniformity for the useful vision field were of 7.65% (intrinsic uniformity) and 2.69% (extrinsic uniformity), in this case the acceptance criterion is a value of 6.00%. The average value of intrinsic spatial resolution went 4.67 mm superior to 4.4. mm that is the acceptance limit. Finally, maximum variations of 1.8% were observed (minors than 2% that is the acceptance criterion) for the extrinsic sensibility measured in different regions of the detector. Significant variations of extrinsic sensibility were not observed among the monthly lectures. Of the realized measurements was concluded that the system requires of a maintenance service by part of the manufacturer, which one carries out later on to this work. The

  16. Compact CdZnTe-Based Gamma Camera For Prostate Cancer Imaging

    Cui, Y.; Lall, T.; Tsui, B.; Yu, J.; Mahler, G.; Bolotnikov, A.; Vaska, P.; DeGeronimo, G.; O'Connor, P.; Meinken, G.; Joyal, J.; Barrett, J.; Camarda, G.; Hossain, A.; Kim, K.H.; Yang, G.; Pomper, M.; Cho, S.; Weisman, K.; Seo, Y.; Babich, J.; LaFrance, N.; James, R.B.

    2011-01-01

    In this paper, we discuss the design of a compact gamma camera for high-resolution prostate cancer imaging using Cadmium Zinc Telluride (CdZnTe or CZT) radiation detectors. Prostate cancer is a common disease in men. Nowadays, a blood test measuring the level of prostate specific antigen (PSA) is widely used for screening for the disease in males over 50, followed by (ultrasound) imaging-guided biopsy. However, PSA tests have a high false-positive rate and ultrasound-guided biopsy has a high likelihood of missing small cancerous tissues. Commercial methods of nuclear medical imaging, e.g. PET and SPECT, can functionally image the organs, and potentially find cancer tissues at early stages, but their applications in diagnosing prostate cancer has been limited by the smallness of the prostate gland and the long working distance between the organ and the detectors comprising these imaging systems. CZT is a semiconductor material with wide band-gap and relatively high electron mobility, and thus can operate at room temperature without additional cooling. CZT detectors are photon-electron direct-conversion devices, thus offering high energy-resolution in detecting gamma rays, enabling energy-resolved imaging, and reducing the background of Compton-scattering events. In addition, CZT material has high stopping power for gamma rays; for medical imaging, a few-mm-thick CZT material provides adequate detection efficiency for many SPECT radiotracers. Because of these advantages, CZT detectors are becoming popular for several SPECT medical-imaging applications. Most recently, we designed a compact gamma camera using CZT detectors coupled to an application-specific-integrated-circuit (ASIC). This camera functions as a trans-rectal probe to image the prostate gland from a distance of only 1-5 cm, thus offering higher detection efficiency and higher spatial resolution. Hence, it potentially can detect prostate cancers at their early stages. The performance tests of this camera

  17. Germanium detectors for nuclear spectroscopy: Current research and development activity at LNL

    Napoli, D. R., E-mail: daniel.r.napoli@lnl.infn.it [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Maggioni, G., E-mail: maggioni@lnl.infn.it; Carturan, S.; Gelain, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); Department of Physics and Astronomy “G. Galilei”, University of Padova, Via Marzolo 8, 35121 Padova (Italy); Eberth, J. [Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln (Germany); Grimaldi, M. G.; Tatí, S. [Department of Physics and Astronomy, University of Catania (Italy); Riccetto, S. [University of Camerino and INFN of Perugia (Italy); Mea, G. Della [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell’Università 2, 35020 Legnaro, Padova (Italy); University of Trento (Italy)

    2016-07-07

    High-purity Germanium (HPGe) detectors have reached an unprecedented level of sophistication and are still the best solution for high-resolution gamma spectroscopy. In the present work, we will show the results of the characterization of new surface treatments for the production of these detectors, studied in the framework of our multidisciplinary research program in HPGe detector technologies.

  18. A specially designed cut-off gamma camera for high resolution SPECT of the brain

    Larsson, S.A.; Bergstrand, G.; Bergstedt, H.; Berg, J.; Flygare, O.; Schnell, P.O.; Anderson, N.; Lagergren, C.

    1984-01-01

    A modern gamma camera system for Single Photon Emission Computed Tomography (SPECT) has been modified in order to optimize examinations of the head. By cutting off a part of the detector housing at one edge, it has been possible to rotate the camera close to the skull, still covering the entire brain and the skull base. The minimum radius of rotation used was thereby reduced, in the mean, from 21.2 cm to 13.0 cm in examination of 18 patients. In combination with an adjustment of the 64 x 64 acquisition matrix to a field of view of 26x26 cm/sup 2/, the spatial resolution improved from 18.6 mm (FWHM) to 12.6 +- 0.3 mm (FWHM) using the conventional LEGP-collimator and to 10.4 +- 0.3 mm (FWHM) using the LEHR-collimator. No other modification than a slight cut of the light guide was made in the internal construction of the camera. Thus, the physical properties of the detector head are not essentially changed from those of a non-modified unit. The improved spatial resolution of the cut-off camera SPECT-system implies certain clinical advantages in studies of the brain, the cerebrospinal fluid (CSF)-space and the skull base

  19. Radioguided Parathyroidectomy with Portable Mini Gamma-Camera for the Treatment of Primary Hyperparathyroidism

    Claudio Casella

    2015-01-01

    Full Text Available Background. A proper localisation of pathological parathyroid glands is essential for a minimally invasive approach in the surgical treatment of primary hyperparathyroidism (PHP. The recent introduction of portable mini gamma-cameras (pMGCs enabled intraoperative scintigraphic scanning. The aim of our study is to evaluate the efficacy of this new method and compare it with the preoperative localisation surveys. Methods. 20 patients were studied; they were evaluated preoperatively by neck ultrasound and Tc-sestaMIBI-scintigraphy and intraoperatively with the pMGC IP Guardian 2. The results obtained from the three evaluations were compared. Results. The pMGC presented a sensitivity of 95%, a specificity of 98.89%, and a diagnostic accuracy of 98.18%, which were higher than those of preoperative ultrasound (sensitivity 55%; specificity 95%; diagnostic accuracy 87% and scintigraphy with Tc-sestaMIBI (sensitivity 73.68%; specificity 96.05%; diagnostic accuracy 91.58%. Conclusions. The pMGC can be used effectively as an intraoperative method to find the correct location of the pathological parathyroid glands. The pMGC is more reliable than the currently used preoperative and intraoperative localisation techniques.

  20. Heart imaging by cadmium telluride gamma camera European Program 'BIOMED' consortium

    Scheiber, C; Chambron, J; Prat, V; Kazandjan, A; Jahnke, A; Matz, R; Thomas, S; Warren, S; Hage-Hali, M; Regal, R; Siffert, P; Karman, M

    1999-01-01

    Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3x3 mm, field of view: 15 cmx15 cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15 deg. tilt of the collimator with respect to the detector grid. A 16x16 CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16...

  1. 3D tomographic imaging with the γ-eye planar scintigraphic gamma camera

    Tunnicliffe, H.; Georgiou, M.; Loudos, G. K.; Simcox, A.; Tsoumpas, C.

    2017-11-01

    γ-eye is a desktop planar scintigraphic gamma camera (100 mm × 50 mm field of view) designed by BET Solutions as an affordable tool for dynamic, whole body, small-animal imaging. This investigation tests the viability of using γ-eye for the collection of tomographic data for 3D SPECT reconstruction. Two software packages, QSPECT and STIR (software for tomographic image reconstruction), have been compared. Reconstructions have been performed using QSPECT’s implementation of the OSEM algorithm and STIR’s OSMAPOSL (Ordered Subset Maximum A Posteriori One Step Late) and OSSPS (Ordered Subsets Separable Paraboloidal Surrogate) algorithms. Reconstructed images of phantom and mouse data have been assessed in terms of spatial resolution, sensitivity to varying activity levels and uniformity. The effect of varying the number of iterations, the voxel size (1.25 mm default voxel size reduced to 0.625 mm and 0.3125 mm), the point spread function correction and the weight of prior terms were explored. While QSPECT demonstrated faster reconstructions, STIR outperformed it in terms of resolution (as low as 1 mm versus 3 mm), particularly when smaller voxel sizes were used, and in terms of uniformity, particularly when prior terms were used. Little difference in terms of sensitivity was seen throughout.

  2. Development of an LYSO based gamma camera for positron and scinti-mammography

    Liang, H.-C.; Jan, M.-L.; Lin, W.-C.; Yu, S.-F.; Su, J.-L.; Shen, L.-H.

    2009-08-01

    In this research, characteristics of combination of PSPMTs (position sensitive photo-multiplier tube) to form a larger detection area is studied. A home-made linear divider circuit was built for merging signals and readout. Borosilicate glasses were chosen for the scintillation light sharing in the crossover region. Deterioration effect caused by the light guide was understood. The influences of light guide and crossover region on the separable crystal size were evaluated. According to the test results, a gamma camera with a crystal block of 90 × 90 mm2 covered area, composed of 2 mm LYSO crystal pixels, was designed and fabricated. Measured performances showed that this camera worked fine in both 511 keV and lower energy gammas. The light loss behaviour within the crossover region was analyzed and realized. Through count rate measurements, the 176Lu nature background didn't show severe influence on the single photon imaging and exhibited an amount of less than 1/3 of all the events acquired. These results show that with using light sharing techniques, combination of multiple PSPMTs in both X and Y directions to build a large area imaging detector is capable to be achieved. Also this camera design is feasible to keep both the abilities for positron and single photon breast imaging applications. Separable crystal size is 2 mm with 2 mm thick glass applied for the light sharing in current status.

  3. Development of an LYSO based gamma camera for positron and scinti-mammography

    Liang, H-C; Jan, M-L; Lin, W-C; Yu, S-F; Shen, L-H; Su, J-L

    2009-01-01

    In this research, characteristics of combination of PSPMTs (position sensitive photo-multiplier tube) to form a larger detection area is studied. A home-made linear divider circuit was built for merging signals and readout. Borosilicate glasses were chosen for the scintillation light sharing in the crossover region. Deterioration effect caused by the light guide was understood. The influences of light guide and crossover region on the separable crystal size were evaluated. According to the test results, a gamma camera with a crystal block of 90 x 90 mm 2 covered area, composed of 2 mm LYSO crystal pixels, was designed and fabricated. Measured performances showed that this camera worked fine in both 511 keV and lower energy gammas. The light loss behaviour within the crossover region was analyzed and realized. Through count rate measurements, the 176 Lu nature background didn't show severe influence on the single photon imaging and exhibited an amount of less than 1/3 of all the events acquired. These results show that with using light sharing techniques, combination of multiple PSPMTs in both X and Y directions to build a large area imaging detector is capable to be achieved. Also this camera design is feasible to keep both the abilities for positron and single photon breast imaging applications. Separable crystal size is 2 mm with 2 mm thick glass applied for the light sharing in current status.

  4. Kernel integration scatter model for parallel beam gamma camera and SPECT point source response

    Marinkovic, P.M.

    2001-01-01

    Scatter correction is a prerequisite for quantitative single photon emission computed tomography (SPECT). In this paper a kernel integration scatter Scatter correction is a prerequisite for quantitative SPECT. In this paper a kernel integration scatter model for parallel beam gamma camera and SPECT point source response based on Klein-Nishina formula is proposed. This method models primary photon distribution as well as first Compton scattering. It also includes a correction for multiple scattering by applying a point isotropic single medium buildup factor for the path segment between the point of scatter an the point of detection. Gamma ray attenuation in the object of imaging, based on known μ-map distribution, is considered too. Intrinsic spatial resolution of the camera is approximated by a simple Gaussian function. Collimator is modeled simply using acceptance angles derived from the physical dimensions of the collimator. Any gamma rays satisfying this angle were passed through the collimator to the crystal. Septal penetration and scatter in the collimator were not included in the model. The method was validated by comparison with Monte Carlo MCNP-4a numerical phantom simulation and excellent results were obtained. The physical phantom experiments, to confirm this method, are planed to be done. (author)

  5. Quantitative studies with the gamma-camera: correction for spatial and energy distortion

    Soussaline, F.; Todd-Pokropek, A.E.; Raynaud, C.

    1977-01-01

    The gamma camera sensitivity distribution is an important source of error in quantitative studies. In addition, spatial distortion produces apparent variations in count density which degrades quantitative studies. The flood field image takes into account both effects and is influenced by the pile-up of the tail distribution. It is essential to measure separately each of these parameters. These were investigated using a point source displaced by a special scanning table with two X, Y stepping motors of 10 micron precision. The spatial distribution of the sensitivity, spatial distortion and photopeak in the field of view were measured and compared for different setting-up of the camera and PM gains. For well-tuned cameras, the sensitivity is fairly constant, while the variations appearing in the flood field image are primarily due to spatial distortion, the former more dependent than the latter on the energy window setting. This indicates why conventional flood field uniformity correction must not be applied. A correction technique to improve the results in quantitative studies has been tested using a continuously matched energy window at every point within the field. A method for correcting spatial distortion is also proposed, where, after an adequately sampled measurement of this error, a transformation can be applied to calculate the true position of events. The knowledge of the magnitude of these parameters is essential in the routine use and design of detector systems

  6. The review of myocardial positron emission computed tomography and positron imaging by gamma camera

    Ohtake, Tohru [Tokyo Univ. (Japan). Faculty of Medicine

    1998-04-01

    To measure myocardial blood flow, Nitrogen-13 ammonia, Oxygen-15 water, Rubidium-82 and et al. are used. Each has merit and demerit. By measuring myocardial coronary flow reserve, the decrease of flow reserve during dipyridamole in patients with hypercholesterolemia or diabetes mellitus without significant coronary stenosis was observed. The possibility of early detection of atherosclerosis was showed. As to myocardial metabolism, glucose metabolism is measured by Fluorine-18 fluorodeoxyglucose (FDG), and it is considered as useful for the evaluation of myocardial viability. We are using FDG to evaluate insulin resistance during insulin clamp in patients with diabetes mellitus by measuring glucose utilization rate of myocardium and skeletal muscle. FFA metabolism has been measured by {sup 11}C-palmitate, but absolute quantification has not been performed. Recently the method for absolute quantification was reported, and new radiopharmaceutical {sup 18}F-FTHA was reported. Oxygen metabolism has been estimated by {sup 11}C-acetate. Myocardial viability, cardiac efficiency was evaluated by oxygen metabolism. As to receptor or sympathetic nerve end, cardiac insufficiency or cardiac transplantation was evaluated. Imaging of positron emitting radiopharmaceutical by gamma camera has been performed. Collimator method is clinically useful for cardiac imaging of viability study. (author). 54 refs.

  7. Feasibility study of a lens-coupled charge-coupled device gamma camera

    Lee, Hakjae; Jung, Youngjun; Kim, Jungmin; Bae, Seungbin; Lee, Kisung; Kang, Jungwon

    2011-01-01

    A charge-coupled device (CCD) is generally used in a digital camera as a light-collecting device such as a photomultiplier tube (PMT). Because of its low sensitivity and very high dark current, CCD have not been popularly used for gamma imaging systems. However, a recent CCD technological breakthrough has improved CCD sensitivity, and the use of a Peltier cooling system can significantly minimize the dark current. In this study, we investigated the feasibility of a prototype CCD gamma camera consisting of a CsI scintillator, optical lenses, and a CCD module. Despite electron-multiplying (EM) CCDs having higher performance, in this study, we built a cost-effective system consisted of low-cost components compared to EMCCDs. Our prototype detector consists of a CsI scintillator, two optical lenses, and a conventional Peltier-cooled CCD. The performance of this detector was evaluated by acquiring the sensitivity, resolution, and the modulation transfer function (MTF). The sensitivity of the prototype detector showed excellent linearity. With a 1 mm-diameter pinhole collimator, the full width at half-maximum (FWHM) of a 1.1 mm Tc-99m line source image was 2.85 mm. These results show that the developed prototype camera is feasible for small animal gamma imaging.

  8. A gamma camera method to monitor the use of degradable starch microspheres in hepatic arterial chemotherapy

    Britten, A.; Fleming, J.; Flowerdew, A.; Hunt, T.; Taylor, I.; Ackery, D.

    1989-01-01

    A gamma camera method to quantify the haemodynamic effects of degradable starch microspheres (DSM) in intra arterial hepatic therapy is described. Results are presented from ten patients with colorectal liver metastases. Intra hepatic arterio venous shunting was present in 1 patient prior to DSM and in 2 subjects after three 300 mg DSM fractions. DSM reduced the rate of flow of injectate to the lung in all cases. Conversely, an increased rate of flow of injectate to gut or spleen occurred with 300 mg fractions of DSM in 7/9 cases. Lower dose DSM fractions are indicated. At 2-3 min after DSM injection the mean fraction of the activity retained in the liver was 0.22. A DSM induced enhancement of tumour relative to normal tissue perfusion was obtained in four out of five tumour regions identified. All indices showed a wide variation between patients and between individual DSM doses, and the high incidence of extra hepatic shunting confirms the need for monitoring when using intra arterial microspheres. (orig.)

  9. Relationship between image quality and changes in spatial resolution for the gamma camera

    Ikeda, Hozumi; Kishimoto, Kenji; Shimonishi, Yoshihiro; Ohmura, Masahiro; Kosakai, Kazuhisa; Hamada, Kunio; Ochi, Hironobu.

    1989-01-01

    The purpose of this study is to examine quantitatively the relationship between visual image quality and degradation in spatial resolution for a gamma camera by the increase in distance from collimator. The relationship between the proportion (p) of images identified the difference of image quality and the difference (δFWHM) in FWHM between paired images was showed in a sigmoid curve. Using Dendy's method, minimum level to be correctly identified the difference of image quality on three out of four occasions (p=0.75) was corresponded to 0.4 mm in δFWHM. Using fuzzy theory, the level to be identified the difference of image quality was examind under various conditions. The truth-value of fuzzy sets-degraded or slightly degraded and not-degraded in image quality between paired images-was gained the peak at 0.5 mm of δFWHM. It was founded that changes of 0.4-0.5 mm in FWHM-corresponding about 2 cm distance from collimator-could be sufficiently identified in the difference of image quality. (author)

  10. Methodology for Gamma cameras calibration for I-131 uptake quantification in Hyperthyroidism diseases

    Lopez Diaz, A.; Palau San Pedro, A.; Martin Escuela, J. M.; Reynosa Montejo, R.; Castillo, J.; Torres Aroche, L.

    2015-01-01

    Optimization and verification of Patient-Specific Treatment Planning with unsealed I-131 sources is a desirable goal from medical and radiation protection point of view. To obtain a practical protocol to combine the estimation of the related parameters with patient's specific treatment dose in hyperthyroidism disease, 3 equipment were studied (Iodine Probe, a Philips Forte Camera with pin-hole collimators and a Mediso Nucline with HEGP for planar and SPECT techniques) and crossed calibrated. The linear behaviour on diagnostic and therapeutic activity range was verified, showing a linear correlation fitting factor R 2 > 0.99. The differences between thyroid uptake determinations in all equipment were less than 6% for therapeutic activities and less than 1.1% in the diagnostic range. The combined protocol to calculate, with only one administration of I 131 , all the necessary parameters to the treatment dose estimation in 2D or 3D, avoiding wasting time with gamma cameras, was established and verified. Following this protocol the difference between apparent and calculated activities were less than 3%. (Author)

  11. Applications of multi-pinhole gamma camera collimation to tomography and image enhancement

    Simpson, D.R.

    1981-01-01

    Recently, multi-pinhole gamma camera collimation has been introduced in the field of emission tomography. This collimation process simultaneously produces several images covering a limited angular range, which may then be recombined to obtain tomographic slices of the object imaged. This study has investigated a possible method for improving the images obtained by this technique by two multi-pinhole views taken 90 0 apart. During the course of this work, multi-pinhole collimation was also applied to in vivo imaging of the disintegration of tablets. Collimmators were designed and built both for tomography and imaging tablet disintegration, and computer programs were written to reconstruct the images by simple backprojection and by filtered backprojection. The use of multi-pinhole collimators to image the disintegration of tablets in vivo was clearly demonstrated. Phantom tests done in vitro were capable of imaging defects as small as 5 mm 2 , while images made with real tablets both in vitro and in vivo readily showed the onset and progress of the tablet disintegration. Further experiments are planned using this technique to measure gastric emptying times disintegration times of various tablet formulations. Limitations of multi-pinhole technique included problems such as limited ranges of viewing and artifacts introduced due to incomplete sampling

  12. Correction of dynamic time-activity curves for gamma-camera dead time, radiotracer delivery, and radioactive decay: special considerations with ultrashort-lived radioisotopes

    Kuruc, A.; Zimmerman, R.E.; Treves, S.

    1985-01-01

    Time-vs.-activity curves obtained by using ultrashort-lived radioisotopes often need to be corrected for the effects of gamma-camera dead time and physical decay. Count loss due to gamma-camera dead time can be monitored by using an electronic oscillator incorporated into the gamma camera. Two algorithms that use this information to correct time-activity curves are discussed. It is also shown that the effect of physical decay on a time-activity curve is dependent on the time course of delivery of the radioisotope to the organ of interest. A mathematical technique that corrects physical decay is described

  13. Assessment of right ventricular function with nonimaging first pass ventriculography and comparison of results with gamma camera studies.

    Zhang, Z; Liu, X J; Liu, Y Z; Lu, P; Crawley, J C; Lahiri, A

    1990-08-01

    A new technique has been developed for measuring right ventricular function by nonimaging first pass ventriculography. The right ventricular ejection fraction (RVEF) obtained by non-imaging first pass ventriculography was compared with that obtained by gamma camera first pass and equilibrium ventriculography. The data has demonstrated that the correlation of RVEFs obtained by the nonimaging nuclear cardiac probe and by gamma camera first pass ventriculography in 15 subjects was comparable (r = 0.93). There was also a good correlation between RVEFs obtained by the nonimaging nuclear probe and by equilibrium gated blood pool studies in 33 subjects (r = 0.89). RVEF was significantly reduced in 15 patients with right ventricular and/or inferior myocardial infarction compared to normal subjects (28 +/- 9% v. 45 +/- 9%). The data suggests that nonimaging probes may be used for assessing right ventricular function accurately.

  14. Growth and characterization of high-purity SiC single crystals

    Augustine, G.; Balakrishna, V.; Brandt, C. D.

    2000-04-01

    High-purity SiC single crystals with diameter up to 50 mm have been grown by the physical vapor transport method. Finite element analysis was used for thermal modeling of the crystal growth cavity in order to reduce stress in the grown crystal. Crystals are grown in high-purity growth ambient using purified graphite furniture and high-purity SiC sublimation sources. Undoped crystals up to 50 mm in diameter with micropipe density less than 100 cm -2 have been grown using this method. These undoped crystals exhibit resistivities in the 10 3 Ω cm range and are p-type due to the presence of residual acceptor impurities, mainly boron. Semi-insulating SiC material is obtained by doping the crystal with vanadium. Vanadium has a deep donor level located near the middle of the band gap, which compensates the residual acceptor resulting in semi-insulating behavior.

  15. Evaluation of intrinsic uniformity of gamma camera in the Servicio de Medicina Nuclear at the Hospital San Juan de Dios

    Mora Ramirez, Erick

    2007-01-01

    The quality assurance program in a nuclear medicine department aims to minimize errors and artifacts that cover all aspects of clinical practice. The quality control can be seen such as one particular procedure used to meet measurements that can be followed along the time. The intrinsic flood-field uniformity is one of the quality control procedures to evaluate the response of a gamma camera to a spatially uniform flux of an incident gamma radiation over the field of view. The gamma cameras, recording the integral and differential uniformity figures of the intrinsic uniformity during the 2007, were evaluated in order to establish how well the instruments were working. An evaluation of the acquisition protocol which implies the variation of the acquired counts, the energy window width and its placement was performed at the beginning. After that the recorded data were analyzed creating plots which were showing the performance of the systems. Using an energy window placed at 140 keV at 20 %, with matrix size of 512 x 512, acquiring 15 million counts and the source activity close to 700 μC; it was thought that good enough images and uniformities are obtained. Both are within the manufactures requirements; however, increasing the number of acquired counts, images are much better and an improvement in the evaluated parameters can be seen. The performance evaluation of the three gamma cameras was taking into account for approximately 240 days, showing an integral uniformity range of 1.04 - 3.5 % and the range for differential uniformity vary from 0.88 up to 2.7 %. It concludes that the gamma cameras were working quite well, no need to vary the acquisition protocol because it is good enough to perform this test. Also, factors affecting the quality of the images are radioactive waste material not very well shielded and temperature room variations, especially at the beginning of the workday. (author) [es

  16. Radiotracer study of wash load movement in a drum-type fabric washing machine using a gamma camera

    Balt, A.P.; Brekel, L.D.M. van den; Vandecasteele, C.; Kolar, Z.

    1987-01-01

    A study was made of the movement of the wash loads in a drum-type washing machine. For this purpose a sup(99m)Tc source was attached to one or two separate textile pieces and the subsequent source positions were determined by means of a gamma-camera. The wash load movement pattern appears to depend on the type of textile material and its amount, as well as on the volume of water present in the washing machine.

  17. Estimated GFR (eGFR by prediction equation in staging of chronic kidney disease compared to gamma camera GFR

    Mohammad Masum Alam

    2016-07-01

    Full Text Available Background: Glomerular filtration rate is an effective tool for diagnosis and staging of chronic kidney disease. The effect ofrenal insufficiency by different method of this tool among patients with CKD is controversial.Objective: The objec­tive of this study was to evaluate the performance of eGFR in staging of CKD compared to gamma camera based GFR.Methods: This cross sectional analytical study was conducted in the Department of Biochemistry Bangabandhu Sheikh Mujib Medical University (BSMMU with the collaboration with National Institute of Nuclear Medicine and Allied Sciences, BSMMU during the period of January 2011 to December 2012. Gama camera based GFR was estimated from DTP A reno gram and eGFR was estimated by three prediction equations. Comparison was done by Bland Altman agree­ment test to see the agreement on the measurement of GFR between three equation based eGFR method and gama camera based GFR method. Staging comparison was done by Kappa analysis to see the agreement between the stages identified by those different methods.Results: Bland-Altman agreement analysis between GFR measured by gamma camera, CG equation ,CG equation corrected by BSA and MDRD equation shows statistically significant. CKD stages determined by CG GFR, CG GFR corrected by BSA , MDRD GFR and gamma camera based GFR was compared by Kappa statistical analysis .The kappa value was 0.66, 0.77 and 0.79 respectively.Conclusions: This study findings suggest that GFR estimation by MDRD equation in CKD patients shows good agreement with gamma camera based GFR and for staging of CKD patients, eGFR by MDRD formula may be used as very effective tool in Bangladeshi population.

  18. Radiotracer study of wash load movement in a drum-type fabric washing machine using a gamma camera

    Balt, A.P.; Brekel, L.D.M. van den; Vandecasteele, C.; Kolar, Z.

    1987-01-01

    A study was made of the movement of the wash loads in a drum-type washing machine. For this purpose a sup(99m)Tc source was attached to one or two separate textile pieces and the subsequent source positions were determined by means of a gamma-camera. The wash load movement pattern appears to depend on the type of textile material and its amount, as well as on the volume of water present in the washing machine. (author)

  19. A new method for elimination of artifacts produced by collimator septum effect in gamma-camera images

    Uchida, Isao; Onai, Yoshio; Tomaru, Teizo; Irifune, Toraji; Kakegawa, Makoto.

    1978-01-01

    Collimator artifacts may be present within the images produced by collimators whose septal width approaches the inherent resolution of the gamma-camera system. As the inherent resolution of the gamma-camera is improved, collimator artifacts become more prominent. The purpose of this study is to eliminate collimator artifacts from gamma-camera images. To eliminate the septum effect produced by high-energy parallel-hole collimators with thick septa, the following method was used: X and Y signals from the detector are made to ride on the triangular waves changing periodically, and resultant position signals obtained by this processing are applied to the corresponding deflection circuits in the CRT display. The oscillation amplitude of processed position signals can be regulated by the frequency and amplitude of the triangular waves. Regulation of the oscillation amplitude of position signals, which would produce maximum reduction of collimator artifacts, was to approach the spatial frequency responses of the overall processed line spread functions obtained experimentally to those of the Gaussian functions with FWHM equal to the geometric resolution calculated from the equation given by Gerber and Miller. In images of a pancreas phantom containing 131 I, collimator artifacts were clearly seen in the unprocessed case, but were eliminated in the processed case. (auth.)

  20. Comparison of myocardial perfusion imaging between the new high-speed gamma camera and the standard anger camera

    Tanaka, Hirokazu; Chikamori, Taishiro; Hida, Satoshi

    2013-01-01

    Cadmium-zinc-telluride (CZT) solid-state detectors have been recently introduced into the field of myocardial perfusion imaging. The aim of this study was to prospectively compare the diagnostic performance of the CZT high-speed gamma camera (Discovery NM 530c) with that of the standard 3-head gamma camera in the same group of patients. The study group consisted of 150 consecutive patients who underwent a 1-day stress-rest 99m Tc-sestamibi or tetrofosmin imaging protocol. Image acquisition was performed first on a standard gamma camera with a 15-min scan time each for stress and for rest. All scans were immediately repeated on a CZT camera with a 5-min scan time for stress and a 3-min scan time for rest, using list mode. The correlations between the CZT camera and the standard camera for perfusion and function analyses were strong within narrow Bland-Altman limits of agreement. Using list mode analysis, image quality for stress was rated as good or excellent in 97% of the 3-min scans, and in 100% of the ≥4-min scans. For CZT scans at rest, similarly, image quality was rated as good or excellent in 94% of the 1-min scans, and in 100% of the ≥2-min scans. The novel CZT camera provides excellent image quality, which is equivalent to standard myocardial single-photon emission computed tomography, despite a short scan time of less than half of the standard time. (author)

  1. Feasibility of the gamma camera acceptance testing procedure introduced by the Swiss Federal Office of public health

    Baechler, S.; Bochud, F.; Verdun, F.R.; Corminboeuf, F.; Linder, R.; Trueb, Ph.; Malterre, J.; Bischof Delaloye, A.

    2006-01-01

    Like in the field of radiology, digital systems are also becoming the standard in the field of nuclear medicine. This offers not only the possibility to process, transmit and archive data from patients more easily but also to introduce quantitative measurements for quality controls. In this framework, standards concerning the qualification of gamma camera systems have been updated and appeared to be useful to set legal requirements, in spite of the fact, that this is not their goals. The aim of this study was first to choose a set of tests described in standards to define measurements to be performed at the acceptance of the systems and after the regular maintenance (at least once every six months). Reference values are then established to control the stability of the system. To verify the feasibility, from a technical and a time requirements points of view, the tests proposed for the quality assurance programme have been applied on three gamma camera systems. The results of this study show that new requirements concerning the quality assurance of gamma camera of the Swiss Federal Office of Public Health based on international standards required to slightly modify some procedures to reduce the time necessary for the acceptance and status tests. (authors)

  2. Scalable preparation of high purity rutin fatty acid esters following enzymatic synthesis

    Lue, Bena-Marie; Guo, Zheng; Xu, Xuebing

    2010-01-01

    Investigations into expanded uses of modified flavonoids are often limited by the availability of these high purity compounds. As such, a simple, effective and relatively fast method for isolation of gram quantities of both long and medium chain fatty acid esters of rutin following scaled......-up biosynthesis reactions was established. Acylation reactions of rutin and palmitic or lauric acids were efficient in systems containing dried acetone and molecular sieves, yielding from 70–77% bioconversion after 96 h. Thereafter, high purity isolates (>97%) were easily obtained in significant quantities...

  3. Dissolution of high-purity lead and subsequent crystal growth during the preparation of corrosion coupons

    McGarvey, G.B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); McDougall, T.E.; Owen, D.G. [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada)

    1997-07-01

    High-purity lead discs were prepared using several combinations of polishing, rinsing and ultrasonic treatment. Physical degradation of the lead surface and the premature generation and deposition of oxides on the surface were observed for certain combinations of preparation steps. Ultrasonic treatment of the discs was found to be particularly detrimental as it induced significant crystal growth and, in several instances, deterioration of the polished surface. Simple air drying of freshly rinsed discs also led to oxide formation on the surface after as short a time as 1 min. An effective method for preparing discs from high-purity lead is described. (author)

  4. Dissolution of high-purity lead and subsequent crystal growth during the preparation of corrosion coupons

    McGarvey, G.B.; McDougall, T.E.; Owen, D.G.

    1997-01-01

    High-purity lead discs were prepared using several combinations of polishing, rinsing and ultrasonic treatment. Physical degradation of the lead surface and the premature generation and deposition of oxides on the surface were observed for certain combinations of preparation steps. Ultrasonic treatment of the discs was found to be particularly detrimental as it induced significant crystal growth and, in several instances, deterioration of the polished surface. Simple air drying of freshly rinsed discs also led to oxide formation on the surface after as short a time as 1 min. An effective method for preparing discs from high-purity lead is described. (author)

  5. Analytical monitoring of systems for the production of high-purity, desalinated water

    Kunert, I.

    1988-01-01

    The purity requirements to be met by high-purity water currently push the most sensitive analytical methods to their utmost limits of sensitivity. The required degree of purity of the water at present can only be achieved by application of membrane processes, and pre-purification of the feedwater to a quality corresponding to that of the raw water source. The contribution in hand discusses the analytical monitoring of the raw water treatment plant, the water treatment prior to the treatment by reverse osmosis, monitoring and control of the modules for reverse osmosis, and the monitoring of high-purity water production for the microelectronics industry. (orig./RB) [de

  6. Potential role of a new hand-held miniature gamma camera in performing minimally invasive parathyroidectomy

    Ortega, Joaquin; Lledo, Salvador [University of Valencia, Clinic University Hospital, Department of Surgery, Valencia (Spain); Ferrer-Rebolleda, Jose [Clinic University Hospital, Department of Nuclear Medicine, Valencia (Spain); Cassinello, Norberto [Clinic University Hospital, Unit of Endocrinologic and Bariatric Surgery, Valencia (Spain)

    2007-02-15

    Sestamibi scans have increased the use of minimally invasive parathyroidectomy (MIP) to treat primary hyperparathyroidism (PHPT) when caused by a parathyroid single adenoma. The greatest concern for surgeons remains the proper identification of pathological glands in a limited surgical field. We have studied the usefulness of a new hand-held miniature gamma camera (MGC) when used intraoperatively to locate parathyroid adenomas. To our knowledge this is the first report published on this subject in the scientific literature. Five patients with PHPT secondary to a single adenoma, positively diagnosed by preoperative sestamibi scans, underwent a MIP. A gamma probe for radioguided surgery and the new hand-held MGC were used consecutively to locate the pathological glands. This new MGC has a module composed of a high-resolution interchangeable collimator and a CsI(Na) scintillating crystal. It has dimensions of around 15 cm x 8 cm x 9 cm and weighs 1 kg. The intraoperative assay of PTH (ioPTH) was used to confirm the complete resection of pathological tissue. All cases were operated on successfully by a MIP. The ioPTH confirmed the excision of all pathological tissues. The MGC proved its usefulness in all patients, even in a difficult case in which the first attempt with the gamma probe failed. In all cases it offered real-time accurate intraoperative images. The hand-held MGC is a useful instrument in MIP for PHPT. It may be used to complement the standard tools used to date, or may even replace them, at least in selected cases of single adenomas. (orig.)

  7. Potential role of a new hand-held miniature gamma camera in performing minimally invasive parathyroidectomy

    Ortega, Joaquin; Lledo, Salvador; Ferrer-Rebolleda, Jose; Cassinello, Norberto

    2007-01-01

    Sestamibi scans have increased the use of minimally invasive parathyroidectomy (MIP) to treat primary hyperparathyroidism (PHPT) when caused by a parathyroid single adenoma. The greatest concern for surgeons remains the proper identification of pathological glands in a limited surgical field. We have studied the usefulness of a new hand-held miniature gamma camera (MGC) when used intraoperatively to locate parathyroid adenomas. To our knowledge this is the first report published on this subject in the scientific literature. Five patients with PHPT secondary to a single adenoma, positively diagnosed by preoperative sestamibi scans, underwent a MIP. A gamma probe for radioguided surgery and the new hand-held MGC were used consecutively to locate the pathological glands. This new MGC has a module composed of a high-resolution interchangeable collimator and a CsI(Na) scintillating crystal. It has dimensions of around 15 cm x 8 cm x 9 cm and weighs 1 kg. The intraoperative assay of PTH (ioPTH) was used to confirm the complete resection of pathological tissue. All cases were operated on successfully by a MIP. The ioPTH confirmed the excision of all pathological tissues. The MGC proved its usefulness in all patients, even in a difficult case in which the first attempt with the gamma probe failed. In all cases it offered real-time accurate intraoperative images. The hand-held MGC is a useful instrument in MIP for PHPT. It may be used to complement the standard tools used to date, or may even replace them, at least in selected cases of single adenomas. (orig.)

  8. Gamma camera based Positron Emission Tomography: a study of the viability on quantification

    Pozzo, Lorena

    2005-01-01

    Positron Emission Tomography (PET) is a Nuclear Medicine imaging modality for diagnostic purposes. Pharmaceuticals labeled with positron emitters are used and images which represent the in vivo biochemical process within tissues can be obtained. The positron/electron annihilation photons are detected in coincidence and this information is used for object reconstruction. Presently, there are two types of systems available for this imaging modality: the dedicated systems and those based on gamma camera technology. In this work, we utilized PET/SPECT systems, which also allows for the traditional Nuclear Medicine studies based on single photon emitters. There are inherent difficulties which affect quantification of activity and other indices. They are related to the Poisson nature of radioactivity, to radiation interactions with patient body and detector, noise due to statistical nature of these interactions and to all the detection processes, as well as the patient acquisition protocols. Corrections are described in the literature and not all of them are implemented by the manufacturers: scatter, attenuation, random, decay, dead time, spatial resolution, and others related to the properties of each equipment. The goal of this work was to assess these methods adopted by two manufacturers, as well as the influence of some technical characteristics of PET/SPECT systems on the estimation of SUV. Data from a set of phantoms were collected in 3D mode by one camera and 2D, by the other. We concluded that quantification is viable in PET/SPECT systems, including the estimation of SUVs. This is only possible if, apart from the above mentioned corrections, the camera is well tuned and coefficients for sensitivity normalization and partial volume corrections are applied. We also verified that the shapes of the sources used for obtaining these factors play a role on the final results and should be delt with carefully in clinical quantification. Finally, the choice of the region

  9. Depth-of-Interaction Compensation Using a Focused-Cut Scintillator for a Pinhole Gamma Camera

    Alhassen, Fares; Kudrolli, Haris; Singh, Bipin; Kim, Sangtaek; Seo, Youngho; Gould, Robert G.; Nagarkar, Vivek V.

    2011-06-01

    Preclinical SPECT offers a powerful means to understand the molecular pathways of drug interactions in animal models by discovering and testing new pharmaceuticals and therapies for potential clinical applications. A combination of high spatial resolution and sensitivity are required in order to map radiotracer uptake within small animals. Pinhole collimators have been investigated, as they offer high resolution by means of image magnification. One of the limitations of pinhole geometries is that increased magnification causes some rays to travel through the detection scintillator at steep angles, introducing parallax errors due to variable depth-of-interaction in scintillator material, especially towards the edges of the detector field of view. These parallax errors ultimately limit the resolution of pinhole preclinical SPECT systems, especially for higher energy isotopes that can easily penetrate through millimeters of scintillator material. A pixellated, focused-cut (FC) scintillator, with its pixels laser-cut so that they are collinear with incoming rays, can potentially compensate for these parallax errors and thus improve the system resolution. We performed the first experimental evaluation of a newly developed focused-cut scintillator. We scanned a Tc-99 m source across the field of view of pinhole gamma camera with a continuous scintillator, a conventional “straight-cut” (SC) pixellated scintillator, and a focused-cut scintillator, each coupled to an electron-multiplying charge coupled device (EMCCD) detector by a fiber-optic taper, and compared the measured full-width half-maximum (FWHM) values. We show that the FWHMs of the focused-cut scintillator projections are comparable to the FWHMs of the thinner SC scintillator, indicating the effectiveness of the focused-cut scintillator in compensating parallax errors.

  10. Evaluation of efficiency of a semiconductor gamma camera eZ-SCOPE AN

    Wang Xinqiang; Wang Wei; Zhu Jiarui; Zhao Wenrui

    2004-01-01

    Objective: To study the basic performance of a compact semiconductor gamma camera (eZ-SCOPE AN) which is constructed using cadmium zinc telluride (CdZnTe) detectors with identical numbers of pixels. Each of the semiconductors sized 2 mm x 2 mm is located in 16 matrix x 16 matrix. The view field is 32 mm x 32 mm. Methods: Using a quality-control phantom, the eZ-SCOPE AN was evaluated. The specific performance characteristics were evaluated as shown below referring to National Electrical Manufacturers Association (NEMA) standards. 1) Intrinsic energy resolution. 2) Intrinsic count rate performance 3) Integral uniformity. 4) System planar sensitivity. 5) Special system resolution. Results: The intrinsic energy resolution [full width at half maximum (FWHM)] was 5.07%. It was failed to determine the maximal intrinsic count rate and the 20% count loss rate with a point source of 37 MBq because the plateau was not reached while using the solutions measured. The integral uniformity was 3.84% with the high sensitivity collimator. The system planer sensitivity was 20 988 counts·min -1 ·MBq -1 with high resolution collimator and 61 090 counts·min -1 ·MBq -1 with high sensitivity collimator. The special system resolution (FWHM) was 2.2 mm when the distance between the source and the collimator was 0 mm and it was 5.7 mm when the distance was 30 mm. Conclusion: This device is of high resolution and high sensitivity and is a reliable tool to investigate radioactivity biodistribution in small organs and small animals. (authors)

  11. Radionuclide examination of the cerebral circulation with the 'Fucks-Knipping Gamma-Camera'

    Arnim, W.H. von; Schicha, H.; Becker, V.; Vyska, K.; Feinendegen, L.E.

    1976-01-01

    In order to analyze cerebral blood flow for diagnostic purposes, Indium 113m-DTPA was i.v. injected into seated patients, and time-activity curves were registered by a multifacet gamma camera (Fucks-Knipping) form 8 regions of interest, from the median area and from the right and left side of the head: 3 from the hemisphere, 3 from the brain stem, 2 from the large arteries of the neck. The results from 14 patients with chronic impairment of cerebral blood flow were compared with normal data from 20 healthy individuals. The time activity curves were analyzed for peak-height, mean transit time, and ratio peak to plateau height. The individual parameters were investigated for the degree of their correlation in a multiparameter system. The results from the patients indicated for the different single parameters a non-uniform response. There was also no correlation between the deviation of different parameters, between single pathological parameters and the degree and the site of blood flow impairment. On the other hand, a positive correlation was found between the number of pathological parameters and the degree of blood flow impairment irrespective of the site of its localization. Reason for this result probably is the variable location and degree of blood flow compensation by collaterals, which predominantly are expected at the cerebral base. The data indicate the potential usefulness of the application of the multiparameter analysis to quantitatively detect the degree of impairment of cerebral blood flow without regard to its topography. In this respect, the method, here described, promises to be of clinical value for non-invasive and non-hazardous diagnostic screening of cerebral blood flow. (orig.) [de

  12. Depth-of-Interaction Compensation Using a Focused-Cut Scintillator for a Pinhole Gamma Camera.

    Alhassen, Fares; Kudrolli, Haris; Singh, Bipin; Kim, Sangtaek; Seo, Youngho; Gould, Robert G; Nagarkar, Vivek V

    2011-06-01

    Preclinical SPECT offers a powerful means to understand the molecular pathways of drug interactions in animal models by discovering and testing new pharmaceuticals and therapies for potential clinical applications. A combination of high spatial resolution and sensitivity are required in order to map radiotracer uptake within small animals. Pinhole collimators have been investigated, as they offer high resolution by means of image magnification. One of the limitations of pinhole geometries is that increased magnification causes some rays to travel through the detection scintillator at steep angles, introducing parallax errors due to variable depth-of-interaction in scintillator material, especially towards the edges of the detector field of view. These parallax errors ultimately limit the resolution of pinhole preclinical SPECT systems, especially for higher energy isotopes that can easily penetrate through millimeters of scintillator material. A pixellated, focused-cut (FC) scintillator, with its pixels laser-cut so that they are collinear with incoming rays, can potentially compensate for these parallax errors and thus improve the system resolution. We performed the first experimental evaluation of a newly developed focused-cut scintillator. We scanned a Tc-99m source across the field of view of pinhole gamma camera with a continuous scintillator, a conventional "straight-cut" (SC) pixellated scintillator, and a focused-cut scintillator, each coupled to an electron-multiplying charge coupled device (EMCCD) detector by a fiber-optic taper, and compared the measured full-width half-maximum (FWHM) values. We show that the FWHMs of the focused-cut scintillator projections are comparable to the FWHMs of the thinner SC scintillator, indicating the effectiveness of the focused-cut scintillator in compensating parallax errors.

  13. Monitoring system for isolated limb perfusion based on a portable gamma camera

    Orero, A.; Muxi, A.; Rubi, S.; Duch, J.; Vidal-Sicart, S.; Pons, F.; Roe, N.; Rull, R.; Pavon, N.; Pavia, J.

    2009-01-01

    Background: The treatment of malignant melanoma or sarcomas on a limb using extremity perfusion with tumour necrosis factor (TNF-α) and melphalan can result in a high degree of systemic toxicity if there is any leakage from the isolated blood territory of the limb into the systemic vascular territory. Leakage is currently controlled by using radiotracers and heavy external probes in a procedure that requires continuous manual calculations. The aim of this work was to develop a light, easily transportable system to monitor limb perfusion leakage by controlling systemic blood pool radioactivity with a portable gamma camera adapted for intraoperative use as an external probe, and to initiate its application in the treatment of MM patients. Methods: A special collimator was built for maximal sensitivity. Software for acquisition and data processing in real time was developed. After testing the adequacy of the system, it was used to monitor limb perfusion leakage in 16 patients with malignant melanoma to be treated with perfusion of TNF-α and melphalan. Results: The field of view of the detector system was 13.8 cm, which is appropriate for the monitoring, since the area to be controlled was the precordial zone. The sensitivity of the system was 257 cps/MBq. When the percentage of leakage reaches 10% the associated absolute error is ±1%. After a mean follow-up period of 12 months, no patients have shown any significant or lasting side-effects. Partial or complete remission of lesions was seen in 9 out of 16 patients (56%) after HILP with TNF-α and melphalan. Conclusion: The detector system together with specially developed software provides a suitable automatic continuous monitoring system of any leakage that may occur during limb perfusion. This technique has been successfully implemented in patients for whom perfusion with TNF-α and melphalan has been indicated. (orig.)

  14. Monitoring system for isolated limb perfusion based on a portable gamma camera

    Orero, A.; Muxi, A.; Rubi, S.; Duch, J. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); Vidal-Sicart, S.; Pons, F. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); Inst. d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona (Spain); Red Tematica de Investigacion Cooperativa en Cancer (RTICC), Barcelona (Spain); Roe, N. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); CIBER de Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona (Spain); Rull, R. [Servei de Cirurgia, Hospital Clinic, Barcelona (Spain); Pavon, N. [Inst. de Fisica Corpuscular, CSIC - UV, Valencia (Spain); Pavia, J. [Servei de Medicina Nuclear, Hospital Clinic, Barcelona (Spain); Inst. d' Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona (Spain); CIBER de Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona (Spain)

    2009-07-01

    Background: The treatment of malignant melanoma or sarcomas on a limb using extremity perfusion with tumour necrosis factor (TNF-{alpha}) and melphalan can result in a high degree of systemic toxicity if there is any leakage from the isolated blood territory of the limb into the systemic vascular territory. Leakage is currently controlled by using radiotracers and heavy external probes in a procedure that requires continuous manual calculations. The aim of this work was to develop a light, easily transportable system to monitor limb perfusion leakage by controlling systemic blood pool radioactivity with a portable gamma camera adapted for intraoperative use as an external probe, and to initiate its application in the treatment of MM patients. Methods: A special collimator was built for maximal sensitivity. Software for acquisition and data processing in real time was developed. After testing the adequacy of the system, it was used to monitor limb perfusion leakage in 16 patients with malignant melanoma to be treated with perfusion of TNF-{alpha} and melphalan. Results: The field of view of the detector system was 13.8 cm, which is appropriate for the monitoring, since the area to be controlled was the precordial zone. The sensitivity of the system was 257 cps/MBq. When the percentage of leakage reaches 10% the associated absolute error is {+-}1%. After a mean follow-up period of 12 months, no patients have shown any significant or lasting side-effects. Partial or complete remission of lesions was seen in 9 out of 16 patients (56%) after HILP with TNF-{alpha} and melphalan. Conclusion: The detector system together with specially developed software provides a suitable automatic continuous monitoring system of any leakage that may occur during limb perfusion. This technique has been successfully implemented in patients for whom perfusion with TNF-{alpha} and melphalan has been indicated. (orig.)

  15. Imaging of radiocesium uptake dynamics in a plant body using a newly developed high-resolution gamma camera for radiocesium

    Kawachi, Naoki; Yin, Yong-Gen; Suzui, Nobuo; Ishii, Satomi; Fujimaki, Shu [Radiotracer Imaging Gr., Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Yoshihara, Toshihiro [Plant Molecular Biology, Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194 (Japan); Watabe, Hiroshi [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, 6-3Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 (Japan); Yamamoto, Seiichi [Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya 461-8673 (Japan)

    2014-07-01

    Vast agricultural and forest areas around the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station in Japan were contaminated with radiocesium (Cs-134 and Cs-137) after the accident following the earthquake and tsunami in March 2011. A variety of agricultural studies, such as fertilizer management and plant breeding, have been undertaken intensively for reduction of radiocesium uptake in crops, or, enhancement of uptake in phyto-remediation. In this study, we newly developed a gamma camera specific for plant nutritional research, and performed quantitative analyses on uptake and partitioning of radiocesium in intact plant bodies. In general, gamma camera is a common technology in medical imaging, but it is not applicable to high-energy gamma rays such as emissions from Cs-137 (662 keV). Therefore, we designed our new gamma camera to prevent the penetration and scattering of the high-energy gamma rays. A single-crystal scintillator, Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG), was employed, which has a relatively high density, a large light output, no natural radioactivity and no hygroscopicity. A 44 x 44 matrix of the Ce:GAGG pixels, with dimensions of 0.85 mm x 0.85 mm x 10 mm for each pixel, was coupled to a high-quantum efficiency position sensitive photomultiplier tube. This gamma detector unit was encased in a 20-mm-thick tungsten container with a tungsten pinhole collimator on the front. By using this gamma camera, soybean plants (Glycine max), grown in hydroponic solutions and fed with 1-2 MBq of Cs-137, were imaged for 6.5 days in maximum to investigate and visualize the uptake dynamics into/within the areal part. As a result, radiocesium gradually appeared in the shoot several hours after feeding of Cs-137, and then accumulated intensively in the maturing pods and seeds in a characteristic pattern. Our results also demonstrated that this gamma-camera method enables quantitative evaluation of plant ability to absorb, transport

  16. Performance assessment of a slat gamma camera collimator for 511 keV imaging. Corrigendum. Phys. Med. Biol., v. 44, p. 1735-1741

    Britten, A.J.; Klie, R.

    1999-01-01

    Further to the recent work on slat gamma camera collimators by Britten and Klie (see above), the authors would like to add some references on the early work in gamma camera slat collimators, which should have been included for completeness. These papers are the original publication by Keyes (1975), and the work carried out by Webb et al (1992, 1993) deriving equations for geometric sensitivity and showing Monte Carlo modelling of performance. (author)

  17. Modeling of dislocation dynamics in germanium Czochralski growth

    Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

    2017-06-01

    Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

  18. High-Purity Fe3S4 Greigite Microcrystals for Magnetic and Electrochemical Performance

    Li, Guowei; Zhang, Baomin; Yu, Feng; Novakova, Alla A.; Krivenkov, Maxim S.; Kiseleva, Tatiana Y.; Chang, Liao; Rao, Jiancun; Polyakov, Alexey O.; Blake, Graeme R.; de Groot, Robert A.; Palstra, Thomas T. M.

    2014-01-01

    High-purity Fe3S4 (greigite) microcrystals with octahedral shape were synthesized via a simple hydrothermal method using a surfactant. The as-prepared samples have the inverse spinel structure with high crystallinity. The saturation magnetization (M-s) reaches 3.74 mu(B) at 5 K and 3.51 mu(B) at

  19. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Pal'-Val', P.P.; Kaufmann, Kh.-J.

    1983-01-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples sub ected to microplastic deformation (epsilon 0 approximately 10 -4 , during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples

  20. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    Pal-Val, P.P.; Kaufmann, H.J.

    1984-01-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation. (author)

  1. Tests of ball bearing used in high-temperature and high-purity water

    Leng Chengmu; Hao Shouxin.

    1987-01-01

    According to the particular conditions and the operation environments in high-temperature and high-purity water, the test content and the measurement instrumentation for the ball bearing were defined. Through various tests, operational performances of the bearing have preliminarily been understood. It provided some useful information for the engineering application of the bearing

  2. Perspectives of data-driven LPV modeling of high-purity distillation columns

    Bachnas, A.A.; Toth, R.; Mesbah, A.; Ludlage, J.H.A.

    2013-01-01

    Abstract—This paper investigates data-driven, Linear- Parameter-Varying (LPV) modeling of a high-purity distillation column. Two LPV modeling approaches are studied: a local approach, corresponding to the interpolation of Linear Time- Invariant (LTI) models identified at steady-state purity levels,

  3. Operation of a high-purity silicon diode alpha particle detector at 1.4 K

    Martoff, C.J.; Kaczanowicz, E.; Neuhauser, B.J.; Lopez, E.; Zhang, Y.; Ziemba, F.P.

    1991-01-01

    Detection of alpha particles at temperatures as low as 1.4 K was demonstrated using a specially fabricated Si diode. The diode was 475 mm 2 by 0.280 mm thick, fabricated from high-purity silicon with degenerately doped contacts. This is an important step toward development of dual-mode (ionization plus phonon) silicon detectors for low energy radiation. (orig.)

  4. High-temperature mechanical properties of high-purity 70 mass% Cr-Fe alloy

    Asahina, M.; Harima, N.; Takaki, S.; Abiko, K. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2002-01-16

    An ingot of high-purity 70 mass% Cr-Fe alloy was prepared by high-frequency induction melting in a high-purity argon atmosphere using a cold copper crucible. Its tensile properties such as hot-ductility and tensile strength were measured, and compared with the results for a high-purity 50 mass% Cr-Fe alloy, a high-purity 60 mass% Cr-Fe alloy and a Ni-based super-alloy. The formation of {sigma}-phase was also examined. The purity of a 70Cr-Fe alloy (70 mass% Cr-Fe alloy) ingot is more than 99.98 mass% and the total amount of gaseous impurities (C, N, O, S, H) in the 70Cr-Fe alloy is 69.9 mass ppm. The strength of the 70Cr-Fe alloy is higher than those of the 60Cr-Fe alloy and the 50Cr-Fe alloy at the temperatures between 293 and 1573 K, without decrease in ductility with increasing Cr content. The 70Cr-Fe alloy also possesses excellent high-temperature ductility. The {sigma}-phase was not observed after aging of 3.6 Ms at 873 K. Consequently, the 70Cr-Fe alloy is an excellent alloy as the base of super heat-resistant alloys. (orig.)

  5. State-of-the-art in analytical characterization of high purity solid ...

    Facilities and some results of several spectroscopic methods which have potential applications in the field of analysis of solid high purity substances and which have been elaborated in Russia, will be discussed in this paper. Laser nondispersive atomic fluorescence method with glow discharge cathode sputtering atomiser, ...

  6. Variation of low temperature internal friction of microplastic deformation of high purity molybdenum single crystals

    Pal-Val, P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, H.J. (Akademie der Wissenschaften der DDR, Berlin)

    1984-08-01

    Amplitude and temperature spectra of ultrasound absorption in weakly deformed high purity molybdenum single crystals of different orientations were measured. The results were discussed in terms of parameter changes related to quasiparticle or dislocation oscillations, respectively, dislocation point defect interactions as well as defect generation at microplastic deformation.

  7. Preparation of uranium-plutonium mixed nitride pellets with high purity

    Arai, Yasuo; Shiozawa, Ken-ichi; Ohmichi, Toshihiko

    1992-01-01

    Uranium-plutonium mixed nitride pellets have been prepared in the gloveboxes with high purity Ar gas atmosphere. Carbothermic reduction of the oxides in N 2 -H 2 mixed gas stream was adopted for synthesizing mixed nitride. Sintering was carried out in various conditions and the effect on the pellet characteristics was investigated. (author)

  8. Diagnosis of myocardial viability by dual-head coincidence gamma camera fluorine-18 fluorodeoxyglucose positron emission tomography with and without non-uniform attenuation correction

    Nowak, B.; Zimmy, M.; Kaiser, H.-J.; Schaefer, W.; Reinartz, P.; Buell, U.; Schwarz, E.R.; Dahl, J. vom

    2000-01-01

    This study assessed a dual-head coincidence gamma camera (hybrid PET) equipped with single-photon transmission for myocardial fluorine-18 fluorodeoxyglucose (FDG) imaging by comparing this technique with conventional positron emission tomography (PET) using a dedicated ring PET scanner. Twenty-one patients were studied with dedicated FDG ring PET and FDG hybrid PET for evaluation of myocardial glucose metabolism, as well as technetium-99 m tetrofosmin single-photon emission tomography (SPET) to estimate myocardial perfusion. All patients underwent transmitted attenuation correction using germanium-68 rod sources for ring PET and caesium-137 point sources for hybrid PET. Ring PET and hybrid PET emission scans were started 61±12 and 98±15 min, respectively, after administration of 154±31 MBq FDG. Attenuation-corrected images were reconstructed iteratively for ring PET and hybrid PET (ac-hybrid PET), and non-attenuation-corrected images for hybrid PET (non-ac-hybrid PET) only. Tracer distribution was analysed semiquantitatively using a volumetric vector sampling method dividing the left ventricular wall into 13 segments. FDG distribution in non-ac-hybrid PET and ring PET correlated with r=0.36 (P<0.0001), and in ac-hybrid PET and ring PET with r=0.79 (P<0.0001). Non-ac-hybrid PET significantly overestimated FDG uptake in the apical and supra-apical segments, and underestimated FDG uptake in the remaining segments, with the exception of one lateral segment. Ac-hybrid PET significantly overestimated FDG uptake in the apical segment, and underestimated FDG uptake in only three posteroseptal segments. A three-grade score was used to classify diagnosis of viability by FDG PET in 136 segments with reduced perfusion as assessed by SPET. Compared with ring PET, non-ac-hybrid PET showed concordant diagnoses in 80 segments (59%) and ac-hybrid PET in 101 segments (74%) (P<0.001). Agreement between ring PET and non-ac-hybrid PET was best in the basal lateral wall and in the

  9. A prototype small CdTe gamma camera for radioguided surgery and other imaging applications.

    Tsuchimochi, Makoto; Sakahara, Harumi; Hayama, Kazuhide; Funaki, Minoru; Ohno, Ryoichi; Shirahata, Takashi; Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar

    2003-12-01

    Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mmx166 mmx65 mm. The effective visual field was 44.8 mmx44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV (99mTc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56 +/- 0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and facilitating

  10. A prototype small CdTe gamma camera for radioguided surgery and other imaging applications

    Tsuchimochi, Makoto; Hayama, Kazuhide [Department of Oral and Maxillofacial Radiology, The Nippon Dental University School of Dentistry at Niigata, 1-8 Hamaura-cho, 951-8580, Niigata (Japan); Sakahara, Harumi [Department of Radiology, Hamamatsu University School of Medicine, Hamamatsu (Japan); Funaki, Minoru; Ohno, Ryoichi; Shirahata, Takashi [Acrorad Co. Ltd., Tokyo (Japan); Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar [Integrated Detector and Electronics A.S (IDE AS), Hovik (Norway)

    2003-12-01

    Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mm x 166 mm x 65 mm. The effective visual field was 44.8 mm x 44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV ({sup 99m}Tc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56{+-}0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and

  11. A prototype small CdTe gamma camera for radioguided surgery and other imaging applications

    Tsuchimochi, Makoto; Hayama, Kazuhide; Sakahara, Harumi; Funaki, Minoru; Ohno, Ryoichi; Shirahata, Takashi; Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar

    2003-01-01

    Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mm x 166 mm x 65 mm. The effective visual field was 44.8 mm x 44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV ( 99m Tc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56±0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and facilitating

  12. Effects of use of the lodine contrast medium on gamma camera imaging

    Pyo, Sung Jae; Cho, Yun Ho [Dept. of Nuclear Medicine, Inha University hospital, Incheon (Korea, Republic of); Choi, Jae Ho [Dept. of Radiological Technology, Ansan College, Ansan (Korea, Republic of)

    2016-12-15

    Effects of Gamma camera imaging on gamma ray counting rates as a function of use and density of the iodine contrast medium currently in primary use for clinics, and changes in gamma ray counting rates as a function of the contrast medium status upon attenuation correction using a CT absorption coefficientin an SPECT/CT attenuation correction will be considered herein. For experimental materials used 99mTcO4 370 MBq and Pamiray 370 mg, Iomeron 350 mg, Visipaque 320 mg, Bonorex 300 mg of iodine contrast medium. For image acquisition, planar imaging was consecutively filmed for 1, 2, 3, 4, 5 min, respectively, 30 min after administration of 99mTcO4. while 60 views were filmed per frame for 20 min at 55 min for the SPECT/CT imaging. In planar imaging, the gamma ray counting rates as a function of filming time were reduced showing a statistically significant difference when mixed according to the type of contrast medium density rather than when the radioactive isotope 99mTcO4 and the saline solution were mixed. In the tomography for mixing of the radioactive isotope 99mTcO4 and saline solution, the mean counting rate without correction by the CT absorption coefficient is 182±26 counts, while the counting rate with correction by the CT absorption coefficient is 531.3±34 counts. In the tomography for mixing of the radioactive isotope 99mTcO4 and the saline solution with the contrast medium, the mean values before attenuation correction by CT absorption coefficient were 166±29, 158.3±17, 154±36, and 150±33 counts depending on the densities of the contrast medium, while the mean values after attenuation correction were 515±03, 503±10, 496±31, and 488.7±33 counts, showing significant differences in both cases when comparatively evaluated with the imaging for no mixing of the contrast medium. Iodine contrast medium affects the rate of gamma ray. Therefore, You should always be preceded before another test on the day of diagnosis.

  13. Implementation of test for quality assurance in nuclear medicine gamma camera

    Moreno, A. Montoya; Laguna, A. Rodríguez; Zamudio, Flavio E. Trujillo

    2012-10-01

    In nuclear medicine (NM) over 90% of procedures are performed for diagnostic purposes. To ensure adequate diagnostic quality of images and the optimization of the doses received by patients originated from the radioactive material is essential for regular monitoring and equipment performance through a quality assurance program (QAP). The QAP consists of 15 proposed performance tomographic and not tomographic gamma camera (GC) tests, and is based on recommendations of international organizations. We describe some results of the performance parameters of QAP applied to a GC model e.cam Siemens, of the Department of NM of the National Cancer Institute of Mexico (INCan). The results were: (1) The average intrinsic spatial resolution (Rin) was 4.67 ± 0.25 mm at the limit of acceptance criterion of 4.4 mm. (2) The sensitivity extrinsic (Sext), with maximum variations of 1.8% (less than 2% which is the criterion of acceptance). (3) Rotational Uniformity (Urot), with values of integral uniformity (IU) in the useful field of view detector (UFOV), with maximum percentage change of 0.97% and monthly variations equal angles, ranging from 0.13 to 0.99% less than 1%. (4) The displacement of the center of rotation (DCOR), indicated a maximum deviation of 0.155 ± 0.039 mm less than 4.795 mm, an absolute deviation of less than 0.5 where pixel 0.085 pixel is suggested, the criteria are assigned to low-energy collimator high resolution. (5) In tomographic uniformity (Utomo), UI values (%) and percentage noise level (rms%) were 7.54 ± 1.53 and 4.18 ± 1.69 which are consistent with the limits of acceptance of 7.0-12.0% and 3.0-6.0% respectively. The smallest cold sphere has a diameter of 11.4 mm. The implementation of a QAP allows for high quality diagnostic images, optimization of the doses given to patients, a reduction of exposure to occupationally exposed workers (POE, by its Spanish acronym), and generally improves the productivity of the service. This proposal can be used to

  14. Dual-head gamma camera system for intraoperative localization of radioactive seeds

    Arsenali, B; Viergever, M A; Gilhuijs, K G A; De Jong, H W A M; Beijst, C; Dickerscheid, D B M

    2015-01-01

    Breast-conserving surgery is a standard option for the treatment of patients with early-stage breast cancer. This form of surgery may result in incomplete excision of the tumor. Iodine-125 labeled titanium seeds are currently used in clinical practice to reduce the number of incomplete excisions. It seems likely that the number of incomplete excisions can be reduced even further if intraoperative information about the location of the radioactive seed is combined with preoperative information about the extent of the tumor. This can be combined if the location of the radioactive seed is established in a world coordinate system that can be linked to the (preoperative) image coordinate system. With this in mind, we propose a radioactive seed localization system which is composed of two static ceiling-suspended gamma camera heads and two parallel-hole collimators. Physical experiments and computer simulations which mimic realistic clinical situations were performed to estimate the localization accuracy (defined as trueness and precision) of the proposed system with respect to collimator-source distance (ranging between 50 cm and 100 cm) and imaging time (ranging between 1 s and 10 s). The goal of the study was to determine whether or not a trueness of 5 mm can be achieved if a collimator-source distance of 50 cm and imaging time of 5 s are used (these specifications were defined by a group of dedicated breast cancer surgeons). The results from the experiments indicate that the location of the radioactive seed can be established with an accuracy of 1.6 mm  ±  0.6 mm if a collimator-source distance of 50 cm and imaging time of 5 s are used (these experiments were performed with a 4.5 cm thick block phantom). Furthermore, the results from the simulations indicate that a trueness of 3.2 mm or less can be achieved if a collimator-source distance of 50 cm and imaging time of 5 s are used (this trueness was achieved for all 14 breast phantoms which

  15. Regional cerebral blood flow measurement using N-isopropyl-p-[123I] iodoamphetamine and rotating gamma camera emission computed tomography

    Matsuda, Hiroshi; Seki, Hiroyasu; Ishida, Hiroko

    1985-01-01

    Thirty-one regional cerebral blood flow (rCBF) measurements were performed on 26 patients with cerebrovascular accidents using N-Isopropyl-p-[ 123 I] Iodoamphetamine ( 123 I-IMP) and rotating gamma camera emission computed tomography (ECT). The equation for determining rCBF is as follows: F=100.R.Cb/(N.A), where F is rCBF in ml/100 g/min., R is the constant withdrawal rate of arterial blood in ml/min., Cb is the brain activity concentration in μCi/g, A is the total activity (5 min.) in the withdrawal arterial whole blood in μCi and N is the fraction of A that is true tracer activity (0.75). In determining Cb at 5 min. after injection, reconstructed counts from 35 min. to 59 min. were corrected to represent those from 4 min. to 5 min. with the use of time activity curve for the entire brain immediately after injection to 30 min. Reconstructed counts of central region in tomographic image were corrected 118% of the obtained values from the result of the countingrate ratio between peripheral and central regions of interests obtained from phantom study. Brain mean blood flow values were distributed from 11 to 39 ml/100 g/min. In 119 cortical regions obtained from 11 measurements in 9 patients, there was a significant correlation (r=0.41, p 123 I-IMP and rotating gamma camera ECT and those from 133 Xe inhalation method. rCBF measurement using 123 I-IMP and rotating gamma camera ECT is not only relatively noninvasive measurement for the entire brain but also three-dimensional evaluation. Besides, it is superior in spatial resolution and accuracy to conventional 133 Xe clearance method. (author)

  16. First 10 kg of naked Germanium detectors in liquid nitrogen installed in the GENIUS-Test-Facility

    Klapdor-Kleingrothaus, H.V.; Chkvorets, O.; Krivosheina, I.V.; Strecker, H.; Tomei, C.

    2003-01-01

    The first four naked high-purity Germanium detectors were installed successfully in liquid nitrogen in the GENIUS-Test-Facility in the GRAN SASSO Underground Laboratory on May 5, 2003. This is the first time ever that this novel technique aiming at extreme background reduction in search for rare decays is going to be tested underground. First operational parameters are presented

  17. Uteroplacental blood flow in diabetic pregnancy: measurements with indium 113m and a computer-linked gamma camera

    Nylund, L.; Lunell, N.O.; Lewander, R.; Persson, B.; Sarby, B.

    1982-01-01

    The uteroplacental blood flow index in the last trimester of pregnancy in 26 women with diabetes mellitus was compared to that in 41 healthy control subjects. After an intravenous injection of 1 mCi of indium 113m, the radiation over the placenta was recorded with a computer-linked gamma camera. From time-activity analysis of the isotope accumulation curve, a uteroplacental blood flow index could be calculated. In the diabetic pregnant women, the maternal-placental blood flow index was reduced 35% to 45% compared to that in healthy women. The blood flow index tended to be further impaired in those diabetic women who had higher blood glucose values

  18. The European Expression Of Interest For High Purity U-233 Materials

    Giaquinto, Joseph M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Younkin, James R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-04-01

    The purpose of this letter report is to document the response for an Expression of Interest (EOI) sent to the European Safeguards and research and development (R&D) scientific communities for the distribution of small amounts of high purity 233U materials for use in safeguards, nonproliferation, and basic R&D in the nuclear disciplines. The intent for the EOI was to gauge the level of international interest for these materials from government and research institutions with programmatic missions in the nuclear security or nuclear R&D arena. The information contained herein is intended to provide information to assist key decision makers in DOE as to the ultimate disposition path for the high purity materials currently being recovered at Oak Ridge National Laboratory (ORNL) and only those items for which there is no United States (U.S.) sponsor identified.

  19. Rare earth impurities in high purity lanthanum oxide determined by neutron activation analysis

    Nguyen Van Suc; Desai, H.B.; Parthasarathy, R.; Gangadharan, S.

    1992-01-01

    Individual rare earth impurities in high purity La 2 O 3 (≥99.9%) have been determined by NAA after pre-separation of the matrix (La). The separation is carried out on an anion exchanger (Dowex 1x8) using different mixtures of methanol/nitric acid as eluants. The rare earth elements from Dy to Lu are eluted quantitatively using a 10% 1M HNO 3 - 90% methanol mixture, while the light rare earths from Ce to Gd are eluted quantitatively using a 10% 0.05M HNO 3 - 90% methanol mixture. La, which is retained on the column, is eluted using 0.1M HNO 3 . The recoveries of the various rare earth elements have been checked using radiotracers and also by spiking the sample with known amount of elements, and the recoveries are found to be quantitative. Results obtained on a typical high purity lanthanum oxide are reported here. (author) 5 refs.; 1 fig

  20. Improved procedure for high purity gaseous peroxyacyl nitrate production: use of heavy lipid solvents

    Gaffney, J S; Fajer, R; Senum, G I

    1984-01-01

    An improved procedure is described for the production of peroxyacyl nitrates (PAN's) in the gas phase. The method of Nielsen et al. (1982) has been modified to yield PAN's of high purity with no further chromatographic purification required. Extraction of PAN's from the nitration of the peracids is accomplished by use of a heavy lipid solvent (n-tridecane). This solvent's low vapor pressure allows the simple separation and preparation of high purity gaseous PAN's (>98%) as determined by Fourier transform infrared spectroscopy (FTIR). Using this method infrared integrated band strengths are reported for peroxyacetyl nitrate (PAN) perdeutero-peroxyacetyl nitrate (PAN-D/sub 3/) and peroxyproprionyl nitrate (PPN). The method allows facile production of large amounts of gaseous PAN's for smog chamber and laboratory studies, toxicological and health effects research, as well as for calibration of PAN analyses.

  1. Approaches to the accurate characterization of high purity metal fluorides and fluoride glasses

    Beary, E. S.; Paulsen, P. J.; Rains, T. C.; Ewing, K. J.; Jaganathan, J.; Aggarwal, I.

    1990-11-01

    The analytical challenges posed by the measurement of trace contaminants in high purity metal fluorides require that innovative chemical preparation procedures be used to enhance existing instrumental techniques. The instrumental techniques used to analyze these difficult matrices must be sensitive enough to detect extremely low levels of trace impurities, and the background interferences derived from the matrix (metal fluoride or glass) must be minimized. A survey of analytical techniques that have the necessary characteristics to analyze these materials will be given. In addition, means of controlling the chemical blank will be presented. Mass and atomic spectrometric techniques will be discussed, specifically graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Analytical procedures using GFAAS and ICP-MS have been developed to determine sub ppb (part per billion) levels of contaminants in high purity fluoride materials.

  2. Fabrication of novel cryomill for synthesis of high purity metallic nanoparticles

    Kumar, Nirmal; Biswas, Krishanu

    2015-08-01

    The successful preparation of free standing metal nanoparticles with high purity in bulk quantity is the pre-requisite for any potential application. This is possible by using ball milling at cryogenic temperature. However, the most of ball mills available in the market do not allow preparing high purity metal nanoparticles by this route. In addition, it is not possible to carry out in situ measurements of process parameters as well as diagnostic of the process. In the present investigation, we present a detailed study on the fabrication of a cryomill, which is capable of avoiding contaminations in the product. It also provides in situ measurements and diagnostic of the low temperature milling process. Online monitoring of the milling temperature and observation of ball motion are the important aspects in the newly designed mill. The nanoparticles prepared using this fabricated mill have been found to be free standing and also free from contaminations.

  3. Comparison of Deformation in High-Purity Single/Large Grain and Polycrystalline Niobium Superconducting Cavities

    Ganapati Rao Myneni; Peter Kneisel

    2005-01-01

    The current approach for the fabrication of superconducting radio frequency (SRF) cavities is to roll and deep draw sheets of polycrystalline high-purity niobium. Recently, a new technique was developed at Jefferson Laboratory that enables the fabrication of single-crystal high-purity Nb SRF cavities. To better understand the differences between SRF cavities fabricated out of fine-grained polycrystalline sheet in the standard manner and single crystal cavities fabricated by the new technique, two half-cells were produced according to the two different procedures and compared using a variety of analytical techniques including optical microscopy, scanning laser confocal microscopy, profilometry, and X-ray diffraction. Crystallographic orientations, texture, and residual stresses were determined in the samples before and after forming and this poster presents the results of this ongoing study

  4. Some aspects of ICP-AES analysis of high purity rare earths

    Murty, P.S.; Biswas, S.S.

    1991-01-01

    Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a technique capable of giving high sensitivity in trace elemental analysis. While the technique possesses high sensitivity, it lacks high selectivity. Selectivity is important where substances emitting complex spectra are to be analysed for trace elements. Rare earths emit highly complex spectra in a plasma source and the determination of adjacent rare earths in a high purity rare earth matrix, with high sensitivity, is not possible due to the inadequate selectivity of ICP-AES. One approach that has yielded reasonably good spectral selectivity in the high purity rare earth analysis by ICP-AES is by employing a combination of wavelength modulation techniques and high resolution echelle grating. However, it was found that by using a high resolution monochromator senstitivities either comparable to or better than those reported by the wavelength modulation technique could be obtained. (author). 2 refs., 2 figs., 2 tabs

  5. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  6. The element analysis of high purity beryllium by method of laser mass-spectrometry

    Virich, V.D.; Kisel', O.V.; Kovtun, K.V.; Pugachev, N.S.; Yakobson, L.A.

    2003-01-01

    The operation is devoted to examination of a possibility of the analysis of element composition pure and high purity model of a beryllium is model by a method of laser mass spectrometry. The advantages of a method in a part of finding of a small amount of admixtures in comparison with other modes of the analysis are exhibited. The possibility of quantitative definition of a content in beryllium samples of gas-making admixtures-C,N,O surveyed

  7. A Study of the Surface Quality of High Purity Copper after Heat Treatment

    Aicheler, M; Atieh, S; Calatroni, S; Riddone, G; Lebet, S; Samoshkin, A

    2011-01-01

    Themanufacturing flow of accelerating structures for the compact linear collider, based on diamond-machined high purity copper components, include several thermal cycles (diffusion bonding, brazing of cooling circuits, baking in vacuum, etc.). The high temperature cycles may be carried out following different schedules and environments (vacuum, reducing hydrogen atmosphere, argon, etc.) and develop peculiar surface topographies which have been the object of extended observations. This study presents and discusses the results of scanning electron microscopy (SEM) and optical microscopy investigations.

  8. Operation of a high-purity silicon diode alpha particle detector at 1. 4 K

    Martoff, C.J.; Kaczanowicz, E. (Temple Univ., Philadelphia, PA (USA)); Neuhauser, B.J.; Lopez, E.; Zhang, Y. (San Francisco State Univ., CA (USA)); Ziemba, F.P. (Quantrad Corp. (USA))

    1991-03-01

    Detection of alpha particles at temperatures as low as 1.4 K was demonstrated using a specially fabricated Si diode. The diode was 475 mm{sup 2} by 0.280 mm thick, fabricated from high-purity silicon with degenerately doped contacts. This is an important step toward development of dual-mode (ionization plus phonon) silicon detectors for low energy radiation. (orig.).

  9. High-purity Cu nanocrystal synthesis by a dynamic decomposition method

    Jian, Xian; Cao, Yu; Chen, Guozhang; Wang, Chao; Tang, Hui; Yin, Liangjun; Luan, Chunhong; Liang, Yinglin; Jiang, Jing; Wu, Sixin; Zeng, Qing; Wang, Fei; Zhang, Chengui

    2014-01-01

    Cu nanocrystals are applied extensively in several fields, particularly in the microelectron, sensor, and catalysis. The catalytic behavior of Cu nanocrystals depends mainly on the structure and particle size. In this work, formation of high-purity Cu nanocrystals is studied using a common chemical vapor deposition precursor of cupric tartrate. This process is investigated through a combined experimental and computational approach. The decomposition kinetics is researched via differential sca...

  10. Analysis of the strain-aging phenomena in high purity niobium: competition between hardening and recovery

    Andreone, C.; Cizeron, G.; Larere, A.

    1981-01-01

    The strain-aging phenomena in high purity niobium were studied using tensile tests. Four parameters were considered which characterize the yield point, the permanent hardening, the recovery and the apparent yield stress. Five successive steps can be distinguished from the changes in these parameters with changes in the aging temperature. The detailed analysis of the phenomena involved concerns mainly the locking of dislocations by first- and second-type segregations and the opposite effect of reorganization of the dislocation network. (Auth.)

  11. Activation analysis of high purity metals and application to study on physical properties

    Ueda, Yoshitake; Hashimoto, Eiji; Matsushita, Rokuji.

    1994-01-01

    In order to determine the true characteristics of matters, the utmost reduction of impurities is indispensable. By the heightening of the purity of aluminum, that of 99.9999% purity has been obtained, but efforts have been exerted to further heighten the purity. For the purpose, it is important to know the behavior of trace impurities during refining, and the quantitative research by neutron activation analysis for various impurities has been carried out. The research on the electron condition of trace impurity atoms in refined aluminum is also important. The band refining of high purity aluminum is explained. By repeating the refining 10 times, the sample of RRR exceeding 30000 was obtained. The impurities contributing to the resistivity are Sc, Ti, V and Cr. Based on the results, the heightening of aluminum purity was attempted by devising the new procedure. As for the electric properties of solute elements in high purity metals, those of transition elements and rare earth elements in aluminum are reported. As the result of measuring the remaining resistance, the sample having the RRR exceeding 45000 after the correction for size effect was done has been obtained. At present, the efforts toward further high purity are continued. (K.I.)

  12. Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

    Mayuzumi, Masami; Ohta, Jyoji; Kako, Kenji

    1998-01-01

    The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce 4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

  13. High purity heavy water production: need for total organic carbon determination in process water streams

    Ayushi; Kumar, Sangita D.; Reddy, A.V.R.; Vithal, G.K.

    2009-01-01

    In recent times, demand for high purity heavy water (99.98% pure) in industries and laboratories has grown by manifold. Its application started in nuclear industry with the design of CANDU reactor, which uses natural uranium as fuel. In this reactor the purest grade of heavy water is used as the moderator and the primary coolant. Diverse industrial applications like fibre optics, medicine, semiconductors etc. use high purity heavy water extensively to achieve better performance of the specific material. In all these applications there is a stringent requirement that the total organic carbon content (TOC) of high purity heavy water should be very low. This is because the presence of TOC can lead to adverse interactions in different applications. To minimize the TOC content in the final product there is a need to monitor and control the TOC content at each and every stage of heavy water production. Hence a simple, rapid and accurate method was developed for the determination of TOC content in process water samples. The paper summarizes the results obtained for the TOC content in the water samples collected from process streams of heavy water production plant. (author)

  14. Calibration of gamma cameras for the evaluation of accidental intakes of high-energy photon emitting radionuclides by humans based on urine samples

    Degenhardt, A.L.; Lucena, E.A.; Reis, A.A. dos; Souza, W.O.; Dantas, A.L.A.; Dantas, B.M., E-mail: bmdantas@ird.gov.br [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Dosimetria

    2017-07-01

    The prompt response to emergency situations involving suspicion of intakes of radionuclides requires the use of simple and rapid methods of internal monitoring of the exposed individuals. The use of gamma cameras to estimate intakes and committed doses was investigated by the Centers for Disease Control and Preventions (CDC) of the USA in 2010.The present study aims to develop a calibration protocol for gamma cameras to be applied on internal monitoring based on urine samples to evaluate the incorporation of high-energy photon emitting radionuclides in emergency situations. A gamma camera available in a public hospital located in the city of Rio de Janeiro was calibrated using a standard liquid source of {sup 152}Eu supplied by the LNMRI of the IRD.'Efficiency vs Energy' curves at 10 and 30 cm were obtained. Calibration factors, Minimum Detectable Activities and Minimum Detectable Effective Doses of the gamma camera were calculated for {sup 137}Cs and {sup 60}Co. The gamma camera evaluated in this work presents enough sensitivity to detect activities of such radionuclides at dose levels suitable to assess suspected accidental intakes. (author)

  15. Long-wavelength germanium photodetectors by ion implantation

    Wu, I.C.; Beeman, J.W.; Luke, P.N.; Hansen, W.L.; Haller, E.E.

    1990-11-01

    Extrinsic far-infrared photoconductivity in thin high-purity germanium wafers implanted with multiple-energy boron ions has been investigated. Initial results from Fourier transform spectrometer(FTS) measurements have demonstrated that photodetectors fabricated from this material have an extended long-wavelength threshold near 192μm. Due to the high-purity substrate, the ability to block the hopping conduction in the implanted IR-active layer yields dark currents of less than 100 electrons/sec at temperatures below 1.3 K under an operating bias of up to 70 mV. Optimum peak responsivity and noise equivalent power (NEP) for these sensitive detectors are 0.9 A/W and 5 x 10 -16 W/Hz 1/2 at 99 μm, respectively. The dependence of the performance of devices on the residual donor concentration in the implanted layer will be discussed. 12 refs., 4 figs

  16. Use of dual-head gamma camera in radionuclide internal contamination monitoring on radiation workers from a nuclear medicine department

    Rodriguez-Laguna, A.; Brandan, M.E.

    2008-01-01

    As a part of an internal dosimetry program that is performed at the Mexican National Institute of Cancerology - Nuclear Medicine Department, in the present work we suggest a procedure for the routinely monitoring of internal contamination on radiation workers and nuclear medicine staff. The procedure is based on the identification and quantification of contaminating radionuclides in human body by using a dual-head whole-body gamma camera. The results have shown that the procedures described in this study can be used to implement a method to quantify minimal accumulated activity in the main human organs to evaluate internal contamination with radionuclides. The high sensitivity of the uncollimated gamma camera is advantageous for the routinely detection and identification of small activities of internal contamination. But, the null spatial resolution makes impossible the definition of contaminated region of interest. Then, the use of collimators is necessary to the quantification of incorporated radionuclides activities in the main human organs and for the internal doses assessment. (author)

  17. Pulse shapes and surface effects in segmented germanium detectors

    Lenz, Daniel

    2010-01-01

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of 76 Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope 76 Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  18. Pulse shapes and surface effects in segmented germanium detectors

    Lenz, Daniel

    2010-03-24

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of {sup 76}Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope {sup 76}Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  19. Measurement of the iodine uptake by the thyroid: comparative analysis between the gamma camera system with 'pinhole' collimator and 13S002 system

    Silva, Carlos Borges da; Mello, Rossana Corbo R. de; Rebelo, Ana Maria O.

    2002-01-01

    The thyroid uptake measurements are common in medical uses and are considered a direct and precise form of diagnostic, however, different results have been observed as measurements of thyroid uptake are taken using distinct equipment. This study attempts to find the cause of the differences between a thyroid uptake probe and a gamma camera. These discrepancies can be associated to the different patients samples, equipment's problems or operator procedures errors. This work presents the results of comparative uptake measurements performed in a neck phantom and a 4-hour thyroid uptake study in 40 patients, using a Gamma Camera Ohio Nuclear model Sigma 410 with a pinhole collimator and Nuclear Medicine System model 13S002, developed by Instituto de Engenharia Nuclear. The results observed show that in spite of non satisfactory results commented in literature, both the System 13S002 and System Gamma Camera Ohio can be used in uptake thyroid diagnostic with statistical confidence degree of 99 %. (author)

  20. Localization of the placenta in the 3 trimester of gestation with the use of a gamma-camera and radioactive sup(113m)In indium isotope

    Brudnik, A.; Chromy, G.; Ulfik, A.; Bielawski, J.; Wasylewski, A. (Slaska Akademia Medyczna, Katowice (Poland))

    1980-01-01

    In 56 women, treated because of uterine bleedings in the 3 trimester of gestation the localization of the placenta was looked for with use of a gamma camera (Toshiba Co.) and indium radioisotope 113-In. The methodic procedures were elaborated for the application of the gamma-camera and the utilization of radioactive marker /sup 125/Sb in the anatomic reference areas. Full conformity of results with findings at cesarean section was met. Isotope placentography with the application of gamma camera gives a high percentage of adequate diagnoses, least dose of exposition, uncomplicated procedures. The negative diagnosis in suspected cases of placenta previa permitted to decrease the time of hospital stay in a number of cases observed because of uterine bleedings in the 3 trimester of pregnancy.

  1. Localization of the placenta in the 3 trimester of gestation with the use of a gamma-camera and radioactive sup(113m)In indium isotope

    Brudnik, A.; Chromy, G.; Ulfik, A.; Bielawski, J.; Wasylewski, A.

    1980-01-01

    In 56 women, treated because of uterine bleedings in the 3 trimester of gestation the localization of the placenta was looked for with use of a gamma camera (Toshiba Co.) and indium radioisotope 113-In. The methodic procedures were elaborated for the application of the gamma-camera and the utilization of radioactive marker 125 Sb in the anatomic reference areas. Full conformity of results with findings at cesarean section was met. Isotope placentography with the application of gamma camera gives a high percentage of adequate diagnoses, least dose of exposition, uncomplicated procedures. The negative diagnosis in suspected cases of placenta previa permitted to decrease the time of hospital stay in a number of cases observed because of uterine bleedings in the 3 trimester of pregnancy. (author)

  2. Liquid-helium scintillation detection with germanium photodiodes

    Luke, P.N.; Haller, E.E.; Steiner, H.M.

    1982-05-01

    Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

  3. The HURRA filter: An easy method to eliminate collimator artifacts in high-energy gamma camera images.

    Perez-Garcia, H; Barquero, R

    The correct determination and delineation of tumor/organ size is crucial in 2-D imaging in 131 I therapy. These images are usually obtained using a system composed of a Gamma camera and high-energy collimator, although the system can produce artifacts in the image. This article analyses these artifacts and describes a correction filter that can eliminate those collimator artifacts. Using free software, ImageJ, a central profile in the image is obtained and analyzed. Two components can be seen in the fluctuation of the profile: one associated with the stochastic nature of the radiation, plus electronic noise and the other periodically across the position in space due to the collimator. These frequencies are analytically obtained and compared with the frequencies in the Fourier transform of the profile. A specially developed filter removes the artifacts in the 2D Fourier transform of the DICOM image. This filter is tested using a 15-cm-diameter Petri dish with 131 I radioactive water (big object size) image, a 131 I clinical pill (small object size) image, and an image of the remainder of the lesion of two patients treated with 3.7GBq (100mCi), and 4.44GBq (120mCi) of 131 I, respectively, after thyroidectomy. The artifact is due to the hexagonal periodic structure of the collimator. The use of the filter on large-sized images reduces the fluctuation by 5.8-3.5%. In small-sized images, the FWHM can be determined in the filtered image, while this is impossible in the unfiltered image. The definition of tumor boundary and the visualization of the activity distribution inside patient lesions improve drastically when the filter is applied to the corresponding images obtained with HE gamma camera. The HURRA filter removes the artifact of high-energy collimator artifacts in planar images obtained with a Gamma camera without reducing the image resolution. It can be applied in any study of patient quantification because the number of counts remains invariant. The filter makes

  4. SU-C-201-07: Validation of a GATE Gamma Camera Model for the Siemens Symbia

    Mikell, J; Siman, W; Kappadath, S; Mourtada, F

    2015-01-01

    Purpose: To develop a simulation model of a clinical gamma camera/SPECT system and to validate the model using experimental and published measurements from the clinical system. Methods: Geant4 Application for Tomographic Emission (GATE) was used to create a model of the Siemens Symbia gamma camera. A modular model was implemented that allows specifying combinations of crystal thickness (3/8”, 5/8”) and collimator (LEHR, MELP, HE). Shielding, energy resolution, intrinsic resolution, crystal thickness, and collimator properties were set based on manufacturer specifications. Validation of the model was performed by simulating NEMA 2007 gamma camera tests including spatial resolution and sensitivity for Tc99; these were compared with experimental and published data for the scanner. The simulated energy spectra of a Tc99 line source in acrylic blocks was visually compared with the corresponding experimental acquisition. For a 4 cm diameter sphere filled with Tc99, the attenuation maps were generated from simulation data, and the photopeak and scatter window were extracted from GATE output using ROOT to create DICOM files to use in the clinical reconstruction. Results: Simulated spatial resolutions for LEHR 3/8” crystal at 0, 10 cm, 10 cm (with scatter), and 30 cm were 4, 6.7, 7.9, and 14.5 mm FWHM; these were 9% less than published data. For 5/8” crystal the spatial resolutions were 4.5, 7.0, 8.5, and 14.7 mm FWHM; these were 4% to 10% less than published data. Simulated sensitivity was within 3.5% of published data for both LEHR 3/8” and 5/8”. The simulated energy spectra matched the photopeak and scatter window well, but did overestimate the counts below 90 keV. The simulated attenuation map and projection data were successfully reconstructed with the clinical software, and the passed visual inspection. Conclusions: Validation of a specific clinical scanner allows future studies of quantification accuracy for both planar and SPECT imaging. Research

  5. SU-C-201-07: Validation of a GATE Gamma Camera Model for the Siemens Symbia

    Mikell, J; Siman, W; Kappadath, S [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX (United States); University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX (United States); Mourtada, F [Christiana Care Hospital, Newark, DE (United States); Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston TX (United States); Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA (United States)

    2015-06-15

    Purpose: To develop a simulation model of a clinical gamma camera/SPECT system and to validate the model using experimental and published measurements from the clinical system. Methods: Geant4 Application for Tomographic Emission (GATE) was used to create a model of the Siemens Symbia gamma camera. A modular model was implemented that allows specifying combinations of crystal thickness (3/8”, 5/8”) and collimator (LEHR, MELP, HE). Shielding, energy resolution, intrinsic resolution, crystal thickness, and collimator properties were set based on manufacturer specifications. Validation of the model was performed by simulating NEMA 2007 gamma camera tests including spatial resolution and sensitivity for Tc99; these were compared with experimental and published data for the scanner. The simulated energy spectra of a Tc99 line source in acrylic blocks was visually compared with the corresponding experimental acquisition. For a 4 cm diameter sphere filled with Tc99, the attenuation maps were generated from simulation data, and the photopeak and scatter window were extracted from GATE output using ROOT to create DICOM files to use in the clinical reconstruction. Results: Simulated spatial resolutions for LEHR 3/8” crystal at 0, 10 cm, 10 cm (with scatter), and 30 cm were 4, 6.7, 7.9, and 14.5 mm FWHM; these were 9% less than published data. For 5/8” crystal the spatial resolutions were 4.5, 7.0, 8.5, and 14.7 mm FWHM; these were 4% to 10% less than published data. Simulated sensitivity was within 3.5% of published data for both LEHR 3/8” and 5/8”. The simulated energy spectra matched the photopeak and scatter window well, but did overestimate the counts below 90 keV. The simulated attenuation map and projection data were successfully reconstructed with the clinical software, and the passed visual inspection. Conclusions: Validation of a specific clinical scanner allows future studies of quantification accuracy for both planar and SPECT imaging. Research

  6. Crystallographic Analysis of Nucleation at Hardness Indentations in High-Purity Aluminum

    Xu, Chaoling; Zhang, Yubin; Lin, Fengxiang

    2016-01-01

    Nucleation at Vickers hardness indentations has been studied in high-purity aluminum cold-rolled 12 pct. Electron channeling contrast was used to measure the size of the indentations and to detect nuclei, while electron backscattering diffraction was used to determine crystallographic orientations....... It is found that indentations are preferential nucleation sites. The crystallographic orientations of the deformed grains affect the hardness and the nucleation potentials at the indentations. Higher hardness gives increased nucleation probabilities. Orientation relationships between nuclei developed...... they form. Finally, possible nucleation mechanisms are briefly discussed....

  7. A fundamental self-generated quenching center for lanthanide-doped high-purity solids

    Auzel, F.

    2002-01-01

    An intrinsic self-generated quenching center for lanthanide-doped high-purity solids is presented for transitions, which cannot be quenched by cross-relaxation. This center, in fact a cluster-like pair of active centers, is shown to come from a particular multiphonon-assisted energy transfer between them. Being due to the vibronic properties of the host it cannot be suppressed. Its role in lanthanide first excited states self-quenching is analyzed and a simple mathematical expression is derived. This law is compared with experimental results for self-quenching in Er-doped fluorophosphate glasses

  8. Synthesis and characterization of straight and stacked-sheet AlN nanowires with high purity

    Lei, M.; Yang, H.; Li, P.G.; Tang, W.H.

    2008-01-01

    Large-scale AlN nanowires with hexagonal crystal structure were synthesized by the direct nitridation method at high temperatures. The experimental results indicate that these single-crystalline AlN nanowires have high purity and consist of straight and stacked-sheet nanowires. It is found that straight AlN nanowire grows along [1, 1, -2, 0] direction, whereas the stacked-sheet nanowire with hexagonal cross section is along [0 0 0 1] direction. It is thought that vapor-solid (VS) mechanism should be responsible for the growth of AlN nanowires

  9. Damage process of high purity tungsten coatings by hydrogen beam heat loads

    Tamura, S.; Tokunaga, K.; Yoshida, N.; Taniguchi, M.; Ezato, K.; Sato, K.; Suzuki, S.; Akiba, M.; Tsunekawa, Y.; Okumiya, M.

    2005-01-01

    To investigate the synergistic effects of heat load and hydrogen irradiation, cyclic heat load tests with a hydrogen beam and a comparable electron beam were performed for high purity CVD-tungsten coatings. Surface modification was examined as a function of the peak temperature by changing the heat flux. Scanning Electron Microscopy analysis showed that the surface damage caused by the hydrogen beam was more severe than that by the electron beam. In the hydrogen beam case, cracking at the surface occurred at all peak temperatures examined from 300 deg. C to 1600 deg. C. These results indicate that the injected hydrogen induces embrittlement for the CVD-tungsten coating

  10. An ICP AES method for determination of dysprosium and terbium in high purity yttrium oxide

    Rupawate, V.H.; Hareendran, K.N.; Roy, S.B.

    2011-01-01

    High purity yttrium finds interesting application in astronavigation, luminescence, nuclear energy and metallurgical industries. Most of these applications require yttrium oxide of highest purity. Consequently there is a need for production of high purity yttrium oxide. Separation and purification of yttrium from other rare earths is a challenging task due to their close chemical properties. Liquid-liquid extraction and ion exchange have been widely used in the production of yttrium oxide of highest purity. Determination of impurities, especially other rare earths, in ppm level is required for process development and chemical characterization of the high purity Y 2 O 3 . Many methods have been described in literature. However since the advent of ICP AES much work in this area has been carried out by this technique. This paper describes the work done for determination of dysprosium (Dy) and terbium (Tb) in yttrium oxide using a high resolution sequential ICP AES. Emission spectra of rare earth elements are very complex and due to this complexity it is important to select spectral interference free analyte lines for determination of rare earths in rare earth matrix. For the determination of Dy and Tb in Y 2 O 3 , sensitive lines of Dy and Tb are selected from the instrument wavelength table and spectral interference free emission lines for the determination is selected by scanning around the selected wavelengths using 5 g/L Y solution and 5 mg/L standard solutions of Dy and Tb prepared in 4% nitric acid. It is found 353.170 nm line of Dy and 350.917 nm line Tb is suitable for quantitative determination. The signal to background ratio increases with increase in matrix concentration, i.e. from 1 to 5 mg/L. The optimum forward power is determined and it is found to be 1100W for Dy and 1000W for Tb. The instrument is calibrated using matrix matched standards containing 5g/L of Y matrix. Samples are dissolved in nitric acid and Y concentration is maintained at 5g/L. Two

  11. Preparation of high-purity cerium nitrate; Preparacao de nitrato de cerio de alta pureza

    Avila, Daniela Moraes; Silva Queiroz, Carlos Alberto da; Santos Mucillo, Eliana Navarro dos [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1995-12-31

    The preparation of high-purity cerium nitrate has been carried out Cerium oxide has been prepared by fractioned precipitation and ionic exchange techniques, using a concentrate with approximately 85% of cerium oxide from NUCLEMON as raw material. Five sequential ion-exchange columns with a retention capacity of 170 g each have been used. The ethylenediamine-tetraacetic acid (EDTA) was used as eluent. The cerium content has been determined by gravimetry and iodometry techniques. The resulting cerium oxide has a purity > 99%. This material was transformed in cerium nitrate to be used as precursor for the preparation of Zirconia-ceria ceramics by the coprecipitation technique. (author) 2 tabs.

  12. Hysec Process: production of high-purity hydrogen from coke oven gas

    Nishida, S

    1984-01-01

    An account is given of the development of the Hysec Process by the Kansai Netsukagaku and Mitsubishi Kakoki companies. The process is outlined and its special features noted. The initial development aim was to obtain high-purity hydrogen from coke oven gas by means of PSA. To achieve this, ways had to be found for removing the impurities in the coke oven gas and the trace amounts of oxygen which are found in the product hydrogen. The resulting hydrogen is 99.9999% pure. 3 references.

  13. Ion-exchange preparation of high-purity vanadium acid from industrial liquors

    Sajdakhmedov, U.A.; Arslanov, Sh.S.; Vulikh, A.I.

    1994-01-01

    The results of investigations on production of special-purity vanadium acid and vanadium oxide directly from process solutions (technical grade liquors) using ionites are presented. Potentiality of thorough purification of vanadium(5) oxide, when producing vanadium acid on the KU-2 cationite with subsequent purification on anionite, is shown. On the basis of the results obtained a principle flowsheet of ion-exchange production of high-purity vanadium(5) oxide from industrial liquors has been developed. 2 refs.; 1 fig.; 4 tabs

  14. Measurement of oxide-layer thickness of internal granules in high-purity aluminium

    Takacs, S.; Ditroi, F.; Mahunka, I.

    1989-01-01

    Charged-particle activation analysis was used for the determination of bulk oxygen concentration in aluminium. High-purity aluminium samples and mixtures containing different amounts of alumina were irradiated by 13 MeV 3 He particles. The aim of the investigation was to determine the oxide-layer thickness on the surface of internal aluminium granules. The measurement was carried out by determining the bulk oxygen concentration in the samples, and calculating the oxide-layer thickness, by using model conditions about the microstructure of the aluminium samples. (author) 5 refs

  15. Formation and evolution of tweed structures on high-purity aluminum polycrystalline foils under cyclic tension

    Kuznetsov, P. V.; Vlasov, I. V.; Sklyarova, E. A.; Smekalina, T. V.

    2015-01-01

    Peculiarities of formation and evolution of tweed structures on the surface of high-purity aluminum polycrystalline foils under cyclic tension were studied using an atom force microscope and a white light interferometer. Tweed structures of micron and submicron sizes were found on the foils at different number of cycles. In the range of 42,000 < N < 95,000 cycles destruction of tweed patterns is observed, which leads to their disappearance from the surface of the foils. Formation of tweed structures of various scales is discussed in terms of the Grinfeld instability

  16. GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

    Heusser, G.; Weber, M.; Hakenmüller, J.; Laubenstein, M.; Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H.

    2015-01-01

    We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut für Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤100 μBq kg -1 for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites

  17. GIOVE: a new detector setup for high sensitivity germanium spectroscopy at shallow depth

    Heusser, G.; Weber, M.; Hakenmueller, J.; Lindner, M.; Maneschg, W.; Simgen, H.; Stolzenburg, D.; Strecker, H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Laubenstein, M. [Laboratori Nazionali del Gran Sasso, Assergi (Italy)

    2015-11-15

    We report on the development and construction of the high-purity germanium spectrometer setup GIOVE (Germanium Inner Outer VEto), recently built and now operated at the shallow underground laboratory of the Max-Planck-Institut fuer Kernphysik, Heidelberg. Particular attention was paid to the design of a novel passive and active shield, aiming at efficient rejection of environmental and muon induced radiation backgrounds. The achieved sensitivity level of ≤ 100μBq kg{sup -1} for primordial radionuclides from U and Th in typical γ ray sample screening measurements is unique among instruments located at comparably shallow depths and can compete with instruments at far deeper underground sites. (orig.)

  18. A study of effects of scattered reaction on physical parameters of a new gamma camera used in nuclear medicine

    Maury, Martine.

    1979-01-01

    This work is devoted to the analysis of the performance of a new gamma camera. This camera is characterized by the introduction of an image amplifier between the crystal detector and the localization system which compound four photomultipliers. The appreciation of performances of this new instrument is based on the measure of the physical parameters usually studied in this purpose: energy resolution, spatial resolution, modulation transfert fonction and contrast, sensitivity and deadtime. Furthermore, we have studied the influence of scattered radiation on the value of these parameters. Two studies complete this work: the artificial deterioration of the energy resolution of the camera inserting a noise, to estimate the importance of the energy resolution on the image contrast; the scanning of pulse amplitude spectra obtained from brain of patients in order to evaluate the participation of scattered radiation in the peak's constitution. We present, at last, a quality control programm for scintillation camera [fr

  19. Multiaxial tomography of heart chambers by gated blood-pool emission computed tomography using a rotating gamma camera

    Tamaki, N.; Mukai, T.; Ishii, Y.; Yonekura, Y.; Yamamoto, K.; Kadota, K.; Kambara, H.; Kawai, C.; Torizuka, K.

    1983-01-01

    Fifteen patients and three volunteers underwent radionuclide blood-pool cardiac studies with electrocardiographic gating. Following conventional planar-gated imaging (anterior and left anterior oblique projections), emission computed tomography (ECT), using a rotating gamma camera, was performed.A series of transaxial tomograms of the cardiac chambers was obtained. The left ventricular short-axis plane, long-axis plane, and four-chamber-view plane were then reorganized; each chamber was visualized separately. Compared to gated planar imaging, this technique showed regional asynergy more clearly in patients with myocardial infarction and demonstrated dilatation of the atria and ventricles more accurately in patients with an atrial septal defect and valvular heart diseases. In addition, when a section of the heart is otained at any angle with gated blood pool ECT, three-dimensional assessment of cardiac chambers in motion is more precise; mutual superimposition becomes unnecessary

  20. ORIS: the Oak Ridge Imaging System program listings. [Nuclear medicine imaging with rectilinear scanner and gamma camera

    Bell, P. R.; Dougherty, J. M.

    1978-04-01

    The Oak Ridge Imaging System (ORIS) is a general purpose access, storage, processing and display system for nuclear medicine imaging with rectilinear scanner and gamma camera. This volume contains listings of the PDP-8/E version of ORIS Version 2. The system is designed to run under the Digital Equipment Corporation's OS/8 monitor in 16K or more words of core. System and image file mass storage is on RK8E disk; longer-time image file storage is provided on DECtape. Another version of this program exists for use with the RF08 disk, and a more limited version is for DECtape only. This latter version is intended for non-medical imaging.

  1. Experimental evaluation of an online gamma-camera imaging of permanent seed implantation (OGIPSI) prototype for partial breast irradiation

    Ravi, Ananth; Caldwell, Curtis B.; Pignol, Jean-Philippe

    2008-01-01

    Previously, our team used Monte Carlo simulation to demonstrate that a gamma camera could potentially be used as an online image guidance device to visualize seeds during permanent breast seed implant procedures. This could allow for intraoperative correction if seeds have been misplaced. The objective of this study is to describe an experimental evaluation of an online gamma-camera imaging of permanent seed implantation (OGIPSI) prototype. The OGIPSI device is intended to be able to detect a seed misplacement of 5 mm or more within an imaging time of 2 min or less. The device was constructed by fitting a custom built brass collimator (16 mm height, 0.65 mm hole pitch, 0.15 mm septal thickness) on a 64 pixel linear array CZT detector (eValuator-2000, eV Products, Saxonburg, PA). Two-dimensional projection images of seed distributions were acquired by the use of a digitally controlled translation stage. Spatial resolution and noise characteristics of the detector were measured. The ability and time needed for the OGIPSI device to image the seeds and to detect cold spots was tested using an anthropomorphic breast phantom. Mimicking a real treatment plan, a total of 52 103 Pd seeds of 65.8 MBq each were placed on three different layers at appropriate depths within the phantom. The seeds were reliably detected within 30 s with a median error in localization of 1 mm. In conclusion, an OGIPSI device can potentially be used for image guidance of permanent brachytherapy applications in the breast and, possibly, other sites

  2. In vivo quantification of {sup 177}Lu with planar whole-body and SPECT/CT gamma camera imaging

    Bailey, Dale L. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Faculty of Health Sciences, University of Sydney, Cumberland, NSW (Australia); Sydney Medical School, University of Sydney, Camperdown, NSW (Australia); NETwork, Sydney Vital, St Leonards, Sydney, NSW (Australia); Hennessy, Thomas M.; Willowson, Kathy P.; Henry, E. Courtney [Institute of Medical Physics, University of Sydney, Camperdown, NSW (Australia); Chan, David L.H. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); NETwork, Sydney Vital, St Leonards, Sydney, NSW (Australia); Aslani, Alireza [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Roach, Paul J. [Department of Nuclear Medicine, Royal North Shore Hospital, St Leonards, NSW 2065 (Australia); Sydney Medical School, University of Sydney, Camperdown, NSW (Australia)

    2015-09-17

    Advances in gamma camera technology and the emergence of a number of new theranostic radiopharmaceutical pairings have re-awakened interest in in vivo quantification with single-photon-emitting radionuclides. We have implemented and validated methodology to provide quantitative imaging of {sup 177}Lu for 2D whole-body planar studies and for 3D tomographic imaging with single-photon emission computed tomography (SPECT)/CT. Whole-body planar scans were performed on subjects to whom a known amount of [{sup 177}Lu]-DOTA-octreotate had been administered for therapy. The total radioactivity estimated from the images was compared with the known amount of the radionuclide therapy administered. In separate studies, venous blood samples were withdrawn from subjects after administration of [{sup 177}Lu]-DOTA-octreotate while a SPECT acquisition was in progress and the concentration of the radionuclide in the venous blood sample compared with that estimated from large blood pool structures in the SPECT reconstruction. The total radioactivity contained within an internal SPECT calibration standard was also assessed. In the whole-body planar scans (n = 28), the estimated total body radioactivity was accurate to within +4.6 ± 5.9 % (range −17.1 to +11.2 %) of the correct value. In the SPECT reconstructions (n = 12), the radioactivity concentration in the cardiac blood pool was accurate to within −4.0 ± 7.8 % (range −16.1 to +7.5 %) of the true value and the internal standard measurements (n = 89) were within 2.0 ± 8.5 % (range −16.3 to +24.2 %) of the known amount of radioactivity contained. In our hands, state-of-the-art hybrid SPECT/CT gamma cameras were able to provide accurate estimates of in vivo radioactivity to better than, on average, ±10 % for use in biodistribution and radionuclide dosimetry calculations.

  3. Surface preparation for high purity alumina ceramics enabling direct brazing in hydrogen atmospheres

    Cadden, Charles H.; Yang, Nancy Yuan Chi; Hosking, Floyd M.

    2001-01-01

    The present invention relates to a method for preparing the surface of a high purity alumina ceramic or sapphire specimen that enables direct brazing in a hydrogen atmosphere using an active braze alloy. The present invention also relates to a method for directly brazing a high purity alumina ceramic or sapphire specimen to a ceramic or metal member using this method of surface preparation, and to articles produced by this brazing method. The presence of silicon, in the form of a SiO.sub.2 -containing surface layer, can more than double the tensile bond strength in alumina ceramic joints brazed in a hydrogen atmosphere using an active Au-16Ni-0.75 Mo-1.75V filler metal. A thin silicon coating applied by PVD processing can, after air firing, produce a semi-continuous coverage of the alumina surface with a SiO.sub.2 film. Room temperature tensile strength was found to be proportional to the fraction of air fired surface covered by silicon-containing films. Similarly, the ratio of substrate fracture versus interface separation was also related to the amount of surface silicon present prior to brazing. This process can replace the need to perform a "moly-manganese" metallization step.

  4. Effect of initial grain size on dynamic recrystallization in high purity austenitic stainless steels

    El Wahabi, M.; Gavard, L.; Montheillet, F.; Cabrera, J.M.; Prado, J.M.

    2005-01-01

    The influence of initial microstructure on discontinuous dynamic recrystallization (DDRX) has been investigated by using high purity and ultra high purity austenitic stainless steels with various initial grain sizes. After uniaxial compression tests at constant strain rates and various temperatures, the steady state microstructure or the state corresponding to the maximum strain (ε = 1) attained in the test was analyzed by scanning electron microscopy aided with automated electron back scattering diffraction. Recrystallized grain size d rec and twin boundary fraction f TB measurements were carried out. The mechanical behavior was also investigated by comparing experimental stress-strain curves with various initial grain sizes. DDRX kinetics was described by the classical Avrami equation. It was concluded that larger initial grain sizes promoted a delay in the DDRX onset in the two alloys. It was also observed that the softening process progressed faster for smaller initial grain sizes. The effect of initial grain size is larger in the HP material and becomes more pronounced at low temperature

  5. A High-Purity Alumina for Use in Studies of Shock Loaded Samples

    Lacina, David; Neel, Christopher

    2017-06-01

    We report the results of plate impact experiments on a potential new ``standard'' material, Coorstek Plasmapure-UC (99.9% purity) polycrystalline alumina, for use in non-conduction, impact environment, shock loading studies. This work was motivated by a desire to find a 99.9% purity alumina to replace the now unavailable Coors Vistal (99.9%) alumina, as it was hoped the Hugoniot elastic limit (HEL) of the new standard would match the 9-11 GPa value of Vistal. Shock response data, including the HEL, Hugoniot particle velocities, Hugoniot shock velocities, stress vs volume, and release wave speeds, was obtained up to 14 GPa. This data will be compared with Hugoniot curve data for other high purity alumina to contrast differences in the shock response, and is intended to be useful in impedance matching calculations. We will show that the HEL of Plasmapure-UC alumina is 5.5 GPa and speculate on causes for this lower than expected value. We will also explore why the elastic-plastic response for Plasmapure-UC alumina differs from what has been observed from other high purity alumina. The final result of this work is to recommend a well-characterized, lower purity alumina (Coorstek AD-995) as a potential new ``standard'' material.

  6. Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

    Smith, L.A. Jr.; Jones, E.M. Jr.; Hearn, D.

    1984-05-08

    Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150 to 250 F at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C[sub 3] to C[sub 6] and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom. 2 figs.

  7. Fused salt processing of impure plutonium dioxide to high-purity plutonium metal

    Mullins, L.J.; Christensen, D.C.; Babcock, B.R.

    1982-01-01

    A process for converting impure plutonium dioxide (approx. 96% pure) to high-purity plutonium metal (>99.9%) was developed. The process consists of reducing the oxide to an impure plutonium metal intermediate with calcium metal in molten calcium chloride. The impure intermediate metal is cast into an anode and electrorefined to produce high-purity plutonium metal. The oxide reduction step is being done now on a 0.6-kg scale with the resulting yield being >99.5%. The electrorefining is being done on a 4.0-kg scale with the resulting yield being 80 to 85%. The purity of the product, which averages 99.98%, is essentially insensitive to the purity of the feed metal. The yield, however, is directly dependent on the chemical composition of the feed. To date, approximately 250 kg of impure oxide has been converted to pure metal by this processing sequence. The availability of impure plutonium dioxide, together with the need for pure plutonium metal, makes this sequence a valuable plutonium processing tool

  8. Wet routes of high purity BaTiO3 nanopowders

    Wang Liqiu; Liu Liang; Xue Dongfeng; Kang Hongmin; Liu Changhou

    2007-01-01

    High purity BaTiO 3 nanopowders were prepared in wet routes through stearic acid gel (SAG) and acetic acid gel (AAG) techniques, respectively. BaTiO 3 samples were characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectrometry, X-ray fluorescence spectrometry, and thermal gravimetric analysis. The present results indicate that both methods have a similar reaction process during calcination, while BaTiO 3 crystallites were initially formed at 550 deg. C by SAG and 800 deg. C by AAG. Both methods could produce BaTiO 3 powders with a cubic perovskite structure, while they had different grain size distributions within 25-50 nm for SAG and 50-80 nm for AAG. BaTiO 3 samples prepared by SAG had a lower agglomeration than those by AAG. SAG has shown many distinctive advantages in the preparation of high purity BaTiO 3 nanopowders, without Ba and Ti losses and hazardous wastes

  9. High-purity Cu nanocrystal synthesis by a dynamic decomposition method

    Jian, Xian; Cao, Yu; Chen, Guozhang; Wang, Chao; Tang, Hui; Yin, Liangjun; Luan, Chunhong; Liang, Yinglin; Jiang, Jing; Wu, Sixin; Zeng, Qing; Wang, Fei; Zhang, Chengui

    2014-12-01

    Cu nanocrystals are applied extensively in several fields, particularly in the microelectron, sensor, and catalysis. The catalytic behavior of Cu nanocrystals depends mainly on the structure and particle size. In this work, formation of high-purity Cu nanocrystals is studied using a common chemical vapor deposition precursor of cupric tartrate. This process is investigated through a combined experimental and computational approach. The decomposition kinetics is researched via differential scanning calorimetry and thermogravimetric analysis using Flynn-Wall-Ozawa, Kissinger, and Starink methods. The growth was found to be influenced by the factors of reaction temperature, protective gas, and time. And microstructural and thermal characterizations were performed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Decomposition of cupric tartrate at different temperatures was simulated by density functional theory calculations under the generalized gradient approximation. High crystalline Cu nanocrystals without floccules were obtained from thermal decomposition of cupric tartrate at 271°C for 8 h under Ar. This general approach paves a way to controllable synthesis of Cu nanocrystals with high purity.

  10. Streamer knotwilg branching: sudden transition in morphology of positive streamers in high-purity nitrogen

    Heijmans, L C J; Clevis, T T J; Nijdam, S; Van Veldhuizen, E M; Ebert, U

    2015-01-01

    We describe a peculiar branching phenomenon in positive repetitive streamer discharges in high purity nitrogen. We name it knotwilg branching after the Dutch word for a pollard willow tree. In a knotwilg branching a thick streamer suddenly splits into many thin streamers. Under some conditions this happens for all streamers in a discharge at about the same distance from the high-voltage electrode tip. At this distance, the thick streamers suddenly bend sharply and appear to propagate over a virtual surface surrounding the high-voltage electrode, rather than following the background electric field lines. From these bent thick streamers many, much thinner, streamers emerge that roughly follow the background electric field lines, creating the characteristic knotwilg branching. We have only found this particular morphology in high purity nitrogen at pressures in the range 50 to 200 mbar and for pulse repetition rates above 1 Hz; the experiments were performed for an electrode distance of 16 cm and for fast voltage pulses of 20 or 30 kV. These observations clearly disagree with common knowledge on streamer propagation. We have analyzed the data of several tens of thousands of discharges to clarify the phenomena. We also present some thoughts on how the ionization of the previous discharges could concentrate into some pre-ionization region near the needle electrode and create the knotwilg morphology, but we present no final explanation. (paper)

  11. Preparation of High Purity CdTe for Nuclear Detector: Electrical and Nuclear Characterization

    Zaiour, A.; Ayoub, M.; Hamié, A.; Fawaz, A.; Hage-ali, M.

    High purity crystal with controllable electrical properties, however, control of the electrical properties of CdTe has not yet been fully achieved. Using the refined Cd and Te as starting materials, extremely high-purity CdTe single crystals were prepared by the traditional vertical THM. The nature of the defects involved in the transitions was studied by analyzing the position of the energy levels by TSC method. The resolution of 4.2 keV (FWHM) confirms the high quality and stability of the detectors: TSC spectrum was in coherence with detectors spectrum with a horizontal plate between 0.2 and 0.6 eV. The enhancement in resolution of detectors with a full width at half- maximum (less than 0.31 meV), lead to confirm that the combination of vacuum distillation and zone refining was very effective to obtain more purified CdTe single crystals for photovoltaic or nuclear detectors with better physical properties.

  12. Trace elements in high purity materials for advanced technology: contribution of neutron activation analysis and radioanalytical technique

    Gallorini, M.; Pietra, R.; Sabbioni, E.

    1991-01-01

    Neutron activation analysis and radioanalytical techniques have been employed to investigate problems related to trace elements and high purity technology materials. Applications of these techniques are overviewed: semiconductor technology as in the case of As and In ion implantation in high purity silicon; problems related to trace elements impurities in thermometric measurements; coating materials to prevent trace elements contamination in biological sampling and metals release from human prostheses. (author) 8 refs.; 2 figs.; 8 tabs

  13. Cryogenic readout techniques for germanium detectors

    Benato, G. [University of Zurich, (Switzerland); Cattadori, C. [INFN - Milano Bicocca, (Italy); Di Vacri, A. [INFN LNGS, (Italy); Ferri, E. [Universita Milano Bicocca/INFN Milano Bicocca, (Italy); D' Andrea, V.; Macolino, C. [GSSI/INFN LNGS, (Italy); Riboldi, S. [Universita degli Studi di Milano/INFN Milano, (Italy); Salamida, F. [Universita Milano Bicocca/INFN Milano Bicocca, (Italy)

    2015-07-01

    High Purity Germanium detectors are used in many applications, from nuclear and astro-particle physics, to homeland security or environment protection. Although quite standard configurations are often used, with cryostats, charge sensitive amplifiers and analog or digital acquisition systems all commercially available, it might be the case that a few specific applications, e.g. satellites, portable devices, cryogenic physics experiments, etc. also require the development of a few additional or complementary techniques. An interesting case is for sure GERDA, the Germanium Detector Array experiment, searching for neutrino-less double beta decay of {sup 76}Ge at the Gran Sasso National Laboratory of INFN - Italy. In GERDA the entire detector array, composed of semi-coaxial and BEGe naked crystals, is operated suspended inside a cryostat filled with liquid argon, that acts not only as cooling medium and but also as an active shield, thanks to its scintillation properties. These peculiar circumstances, together with the additional requirement of a very low radioactive background from all the materials adjacent to the detectors, clearly introduce significant constraints on the design of the Ge front-end readout electronics. All the Ge readout solutions developed within the framework of the GERDA collaboration, for both Phase I and Phase II, will be briefly reviewed, with their relative strength and weakness compared together and with respect to ideal Ge readout. Finally, the digital processing techniques developed by the GERDA collaboration for energy estimation of Ge detector signals will be recalled. (authors)

  14. Experience from operating germanium detectors in GERDA

    Palioselitis, Dimitrios; GERDA Collaboration

    2015-05-01

    Phase I of the Germanium Detector Array (GERDA) experiment, searching for the neutrinoless double beta (0νββ) decay of 76Ge, was completed in September 2013. The most competitive half-life lower limit for the 0νββ decay of 76Ge was set (T-0ν1/2 > 2.1 · 1025 yr at 90% C.L.). GERDA operates bare Ge diodes immersed in liquid argon. During Phase I, mainly refurbished semi-coaxial high purity Ge detectors from previous experiments were used. The experience gained with handling and operating bare Ge diodes in liquid argon, as well as the stability and performance of the detectors during GERDA Phase I are presented. Thirty additional new enriched BEGe-type detectors were produced and will be used in Phase II. A subgroup of these detectors has already been used successfully in GERDA Phase I. The present paper gives an overview of the production chain of the new germanium detectors, the steps taken to minimise the exposure to cosmic radiation during manufacturing, and the first results of characterisation measurements in vacuum cryostats.

  15. Experience from operating germanium detectors in GERDA

    Palioselitis, Dimitrios

    2015-01-01

    Phase I of the Germanium Detector Array (GERDA) experiment, searching for the neutrinoless double beta (0νββ) decay of 76 Ge, was completed in September 2013. The most competitive half-life lower limit for the 0νββ decay of 76 Ge was set (T- 0ν 1/2 > 2.1 · 10 25 yr at 90% C.L.). GERDA operates bare Ge diodes immersed in liquid argon. During Phase I, mainly refurbished semi-coaxial high purity Ge detectors from previous experiments were used. The experience gained with handling and operating bare Ge diodes in liquid argon, as well as the stability and performance of the detectors during GERDA Phase I are presented. Thirty additional new enriched BEGe-type detectors were produced and will be used in Phase II. A subgroup of these detectors has already been used successfully in GERDA Phase I. The present paper gives an overview of the production chain of the new germanium detectors, the steps taken to minimise the exposure to cosmic radiation during manufacturing, and the first results of characterisation measurements in vacuum cryostats. (paper)

  16. Electromechanically cooled germanium radiation detector system

    Lavietes, Anthony D.; Joseph Mauger, G.; Anderson, Eric H.

    1999-01-01

    We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++, GAMANL, GRPANL and MGAU, typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service . The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted

  17. Radiochemical neutron activation analysis based multi-elemental analysis of high purity gallium

    Tashimova, F.A.; Sadikov, I.I; Salimov, M.I.; Zinov'ev, V.G.

    2006-01-01

    Full text: Gallium is one of the widely used materials in semiconductor and optoelectronics industry. Gallium is used to produce infrared detectors, piezoelectric sensors, high- and low-temperature transistors for space and defense technology. One of the most important requirements for semiconductor materials of gallium compounds is an excessive high purity for layers and films. Information on impurities (type of an impurity, concentration, character of distribution) is important as for better understanding of the physical and chemical processes taking place in formed semiconductor structures and for the 'know-how' of devices on their basis. The object of this work is to develop radiochemical neutron activation technique for analysis of high purity gallium. Irradiation of 0.1 g of gallium sample in neutron flux of 5·10 13 cm -2 s -1 for 5 hours will result in induced activity of more than 10 8 Bq, due to 72 Ga radionuclide, half-life of which is 14.1 hours. Therefore to perform instrumental NAA of gallium long period (10 day) cooling is required, and high sensitive determination of elements producing short- and long-lived radionuclides (T 1/2 72 Ga. We have studied the behavior of gallium in extraction-chromatographic system 'TBP-HCl'. The experiments have shown that higher factor of distribution (D) and capacity on gallium can be achieved when 'TBP-4M HCl' system is used. However more than 10 trace elements have high D and thus they cannot be separated from 72 Ga. To resolve the problem and increase the number of separated trace elements we have used preliminary satisfaction of chromatographic column with tellurium, which has D higher than the most of elements in 'TBP-4M HCl' system and thus suppresses extraction of elements. Distribution profile of gallium along the column and elution curve of 25 trace elements have been measured. Chemical yields of separated elements measured by using radiotracers are more than 93%. On the basis of the carried out researches

  18. A radioagent method for determination of traces of phosphorus in high-purity silicon

    Chen, P.Y.; Chen, J.S.; Sun, H.J.; Yang, M.H.

    1985-01-01

    The feasibility of the determination of phosphorus at the extreme trace levels in high-purity silicon by radioreagent method is explored. After silicon dissolution with hydrofluoric and nitric acids and matrix volatilization, 12-molybdophosphoric acid is formed by the addition of the reagent, sup(99)MoOsub(4)sup(2-), in nitric acid medium and then extracted into isobutyl acetate. By plotting the phosphorus content against the radioactivity of sup(99)Mo in the organic phase, a linear relationship persisting down to 5 ng is obtained. Special effort was made to eliminate the unreacted sup(99)MoOsub(4)sup(2-) reagent and the optimal control of phosphorus blank introduced through the multistage analytical procedure in order to ensure reliable determination of phosphorus at the ppb level. (author)

  19. Physical and mechanical metallurgy of high purity Nb for accelerator cavities

    Bieler, T.R.; Wright, N.T.; Pourboghrat, F.; Compton, C.; Hartwig, K.T.; Baars, D.; Zamiri, A.; Chandrasekaran, S.; Darbandi, P.; Jiang, H.; Skoug, E.; Balachandran, S.; Ice, G.E.; Liu, W.

    2010-01-01

    In the past decade, high Q values have been achieved in high purity Nb superconducting radio frequency (SRF) cavities. Fundamental understanding of the physical metallurgy of Nb that enables these achievements is beginning to reveal what challenges remain to establish reproducible and cost-effective production of high performance SRF cavities. Recent studies of dislocation substructure development and effects of recrystallization arising from welding and heat treatments and their correlations with cavity performance are considered. With better fundamental understanding of the effects of dislocation substructure evolution and recrystallization on electron and phonon conduction, as well as the interior and surface states, it will be possible to design optimal processing paths for cost-effective performance using approaches such as hydroforming, which minimizes or eliminates welds in a cavity.

  20. Efficiency correction for disk sources using coaxial High-Purity Ge detectors

    Chatani, Hiroshi.

    1993-03-01

    Efficiency correction factors for disk sources were determined by making use of closed-ended coaxial High-Purity Ge (HPGe) detectors, their relative efficiencies for a 3' 'x3' ' NaI(Tl) with the 1.3 MeV γ-rays were 30 % and 10 %, respectively. Parameters for the correction by mapping method were obtained systematically, using several monoenergetic (i.e. no coincidence summing loses) γ-ray sources produced by irradiation in the Kyoto University Reactor (KUR) core. These were found out that (1) the systematics of the Gaussian fitting parameters, which were calculated using the relative efficiency distributions of HPGe, to the γ-ray energies are recognized, (2) the efficiency distributions deviate from the Gaussian distributions outside of the radii of HPGe. (3) mapping method is a practical use in satisfactory accuracy, as the results in comparison with the disk source measurements. (author)

  1. Se-Se isoelectronic centers in high purity CdTe

    Najjar, Rita; Andre, Regis; Mariette, Henri [CEA-CNRS, Nanophysique et Semiconducteurs, Institut Neel, 25 rue des martyrs, 38042 Grenoble (France); Golnik, Andrzej; Kossacki, Piotr; Gaj, Jan A. [Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warsaw (Poland)

    2010-06-15

    We evidence zero-dimensional exciton states trapped on isoelectronic Se centers in CdTe quantum wells, {delta}-doped with Se. Thanks to special precautions taken to have very high purity CdTe heterostructures, it is possible to observe, in photoluminescence spectra, sharp discrete lines arising from individual centers related to the Se doping. These emission lines appear at about 40 meV below the CdTe band gap energy. The most prominent lines are attributed to the recombination of excitons bound to nearest-neighbor selenium pairs in a tetrahedral CdTe environment. This assignment is confirmed by a common linear polarization direction of the emitted light, parallel to <110>. These excitons localized on individual isoelectronic traps are good candidates as single photon emitters (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Temperature dependence of luminescence for different surface flaws in high purity silica glass

    Fournier, J.; Grua, P.; Neauport, J.; Fargin, E.; Jubera, V.; Talaga, D.; Del Guerzo, A.; Raffy, G.; Jouannigot, S.

    2013-01-01

    In situ temperature dependence of the Photoluminescence under 325 nm irradiation is used to investigate defect populations existing in different surface flaws in high purity fused silica. Five photoluminescence bands peaking at 1.9, 2.1, 2.3, 2.63 and 3.11 eV have been detected in the spectral area ranging from 1.6 up to 3.6 eV. The Gaussian deconvolution of spectra allows dividing the five luminescence bands in two categories. The former corresponds to bands showing a significant intensity enhancement while temperature decreases; the latter corresponds to bands remaining insensitive to the temperature evolution. Such a behavior brings new information on defects involved in laser damage mechanism at 351 nm in nanosecond regime. (authors)

  3. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Pal' -Val' , P.P.; Kaufmann, Kh.J.

    1983-03-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples sub ected to microplastic deformation (epsilon<=0.45%) were used. Unstrained samples displayed at T<30 K a rapid increase in the absorption with lowering temperature which is interpreted as an indication of electron viscosity due to electron-phonon collisions. After deformation this part of absorption disappeared. This seems to suggest that microplastic deformation brings about in the crystal a sufficiently large number of defects that can compete with phonons in restricting the electron mean free path. A low temperature dynamic annealing has been revealed in strained samples, that is almost complete recovery of the absorption nature under irradiation with high amplitude sound, epsilon/sub 0/ approximately 10/sup -4/, during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples.

  4. High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap

    Han Chulwoong

    2015-06-01

    Full Text Available Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungsten carbide-cobalt hard metal scrap was mechanically broken into particles and then tungsten trioxide particle was recovered by hydrometallurgical method. Recovered tungsten trioxide was reduced to tungsten particle in a hydrogen environment. After that, tungsten particle was melted and solidified to make a spherical one by RF (Ratio Frequency thermal plasma process. Well spherical tungsten micro-particle was successfully obtained from spent scrap. In addition to the morphological change, thermal plasma process showed an advantage for the purification of feedstock particle.

  5. Facile synthesis of upconversion nanoparticles with high purity using lanthanide oleate compounds

    Kang, Ning; Ai, Chao-Chao; Zhou, Ya-Ming; Wang, Zuo; Ren, Lei

    2018-02-01

    A novel strategy for preparing highly pure NaYF4-based upconversion nanoparticles (UCNPs) was developed using lanthanide oleate compounds [Ln(OA)3] as the precursor, denoted as the Ln-OA preparation method. Compared to the conventional solvothermal method for synthesizing UCNPs using lanthanide chloride compounds (LnCl3) as the precursor (denoted as the Ln-Cl method), the Ln-OA strategy exhibited the merits of high purity, reduced purification process and a uniform size in preparing core and core-shell UCNPs excited by a 980 or 808 nm near infrared (NIR) laser. This work sheds new insight on the preparation of UCNPs and promotes their application in biomedical fields.

  6. Computers in the investigation of the impurity content of high-purity materials

    Makarov, Yu.B.; Yan'kov, S.V.

    1987-01-01

    The efficiency of the concept of data banks for the accumulation and processing of information is now generally acknowledged. In scientific investigations not only bibliographic but also factual data banks are becoming more and more prevalent. In this article, the authors consider the possibilities of providing a data bank on high-purity materials for the study of impurity contents. Also in this paper, the authors distinguish the following groups of problems that arise in the study of impurity composition and presents examples of their proposed solutions to these problems: the analysis of error and the determination of the most probably value of impurity concentration; the estimation of average properties of impurity composition with respect to groups of impurities and samples, and the forecast of the complete impurity composition

  7. Sensor locations and noise reduction in high-purity batch distillation control loops

    Oisiovici R.M.

    2000-01-01

    Full Text Available The influence of the sensor locations on the composition control of high-purity batch distillation columns has been investigated. Using concepts of the nonlinear control theory, an input-output linearizing controller was implemented to keep the distillate composition constant at a desired value by varying the reflux ratio. An Extended Kalman Filter was developed to estimate the compositions required in the control algorithm using temperature measurements. In the presence of measurement noise, the control performance depended greatly on the sensor locations. Placing the sensors further from the top stages reduced the detrimental effects of noise but increased the inference error. To achieve accurate composition control, both noise reduction and composition estimate accuracy should be considered in the selection of the sensor locations.

  8. Physical and mechanical metallurgy of high purity Nb for accelerator cavities

    T. R. Bieler

    2010-03-01

    Full Text Available In the past decade, high Q values have been achieved in high purity Nb superconducting radio frequency (SRF cavities. Fundamental understanding of the physical metallurgy of Nb that enables these achievements is beginning to reveal what challenges remain to establish reproducible and cost-effective production of high performance SRF cavities. Recent studies of dislocation substructure development and effects of recrystallization arising from welding and heat treatments and their correlations with cavity performance are considered. With better fundamental understanding of the effects of dislocation substructure evolution and recrystallization on electron and phonon conduction, as well as the interior and surface states, it will be possible to design optimal processing paths for cost-effective performance using approaches such as hydroforming, which minimizes or eliminates welds in a cavity.

  9. In vitro characterization of high purity factor IX concentrates for the treatment of hemophilia B.

    Limentani, S A; Gowell, K P; Deitcher, S R

    1995-04-01

    This study employed sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and immunoblotting to assess the purity of seven high purity factor IX concentrates: Aimafix (Aima), AlphaNine-SD (Alpha Therapeutic), Factor IX VHP (Biotransfusion), Immunine (Immuno), Mononine (Armour Pharmaceutical), Nanotiv (Kabi Pharmacia), and 9MC (Blood Products Laboratory). The mean specific activity of these products ranged from 68 U factor IX/mg (Aimafix) to 246 U factor IX/mg (Mononine). SDS-PAGE analysis showed that the highest purity product, Mononine, had a single contaminating band under non-reducing conditions. Two additional bands were detected when this product was analyzed under reducing conditions. All other products had multiple contaminating bands that were more apparent under reducing than non-reducing conditions. The immunoblot for factor IX showed a dominant factor IX band for all products. In addition, visible light chain of factor IX was detected for AlphaNine-SD, Factor IX VHP, Immunine, Mononine, Nanotiv, and 9MC, suggesting that the factor IX in these products had undergone partial activation to factor IXa. Another contaminating band was visible at 49,500 for all of the products except 9MC. In addition to this band, high molecular weight contaminants were apparent for some products, most notably AlphaNine-SD. The identity of these bands is unknown. Immunoblotting failed to demonstrate factor VII as a contaminant of any of the high purity products, although factor VIIa could be detected in some lots of Immunine, Nanotiv, and 9MC by a clot-based assay. Factor X contaminated Aimafix, AlphaNine-SD, Factor IX VHP, Immunine, Nanotiv, and 9MC, but activation products of factor X were not detected.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Recycling of high purity selenium from CIGS solar cell waste materials

    Gustafsson, Anna M.K., E-mail: anna.gustafsson@chalmers.se; Foreman, Mark R.StJ.; Ekberg, Christian

    2014-10-15

    Highlights: • A new method for recycling of selenium from CIGS solar cell materials is presented. • Separation of selenium as selenium dioxide after heating in oxygen atmosphere. • Complete selenium separation after oxidation of <63 μm particles at 800 °C for 1 h. • After reduction of selenium dioxide the selenium purity was higher than 99.999 wt%. - Abstract: Copper indium gallium diselenide (CIGS) is a promising material in thin film solar cell production. To make CIGS solar cells more competitive, both economically and environmentally, in comparison to other energy sources, methods for recycling are needed. In addition to the generally high price of the material, significant amounts of the metals are lost in the manufacturing process. The feasibility of recycling selenium from CIGS through oxidation at elevated temperatures was therefore examined. During oxidation gaseous selenium dioxide was formed and could be separated from the other elements, which remained in solid state. Upon cooling, the selenium dioxide sublimes and can be collected as crystals. After oxidation for 1 h at 800 °C all of the selenium was separated from the CIGS material. Two different reduction methods for reduction of the selenium dioxide to selenium were tested. In the first reduction method an organic molecule was used as the reducing agent in a Riley reaction. In the second reduction method sulphur dioxide gas was used. Both methods resulted in high purity selenium. This proves that the studied selenium separation method could be the first step in a recycling process aimed at the complete separation and recovery of high purity elements from CIGS.

  11. Monitoring of the internal contamination of occupationally exposure personnel in services of nuclear medicine through the use of gamma cameras

    Teran, M.; Paolino, A.; Savio, E.; Hermida, J.C.; Dantas, B.M.

    2006-01-01

    The radionuclides incorporation can happen as a result of diverse activities; these include the work associated with the different stadiums of the nuclear fuel cycle, the use of radioactive sources in medicine, the scientific research, the agriculture and the industry. In Uruguay the main activities linked to the manipulation of open sources correspond those of Nuclear Medicine and from 2004, in the mark of the Project Arcal RLA 049 and being based on the Safety Guides of the IAEA it is implementing a program of internal monitoring in combined form the Nuclear Medicine Center of the Hospital of and the Radiochemistry class of the Faculty of Chemistry. In accordance with the publication of the ICRP 75 the emphasis of any monitoring program should be in the formal study of the doses in the workers to who are considered commendable of to receive in routine form an outstanding fraction of the dose limits or who work in areas where the exposures can be significant in the accident event. From April 2004, to the date has started a pilot plan by means of in that were established appropriate conditions of procedures and of safety in a reduced group of workers of the Nuclear Medicine area. In that period the first work limits, equipment adjustment, calibrations and registration systems were determined. The monitoring system implemented until the moment is carried out with a thyroid caption equipment. However these measurements are carried out in the university hospital embracing 40% of the involved workers of our country, with the purpose of reaching the covering of the biggest quantity of occupationally exposed personnel of private clinics. Also it was developed a new work proposal that allows to have an alternative measure method, in the event of not having the equipment habitually used. Among the conclusions of this work are that for the before exposed are considered the measure conditions but appropriate the following ones: Gamma Camera without collimator; Measurement

  12. Simultaneous determination of dysprosium, holmium and erbium in high purity rare earth oxides by second order derivative spectrophotometry

    Anbu, M.; Prasada Rao, T.; Iyer, C. S. P.; Damodaran, A. D.

    1996-01-01

    High purity individual rare earth oxides are increasingly used as major components in lasers (Y 2 O 3 ), phosphors (YVO 3 , Eu 2 O 3 ), magnetic bubble memory films (Gd 2 O 3 ) and refractive-index lenses and fibre optics (La 2 O 3 ). The determination of individual lanthanides in high purity rare earth oxides is a more important and difficult task. This paper reports the utilization of higher order derivative spectrophotometry for the simultaneous determination of dysprosium, holmium and erbium in high purity rare earth oxides. The developed procedure is simple, reliable and allows the determination of 0.001 to 0.2% of dysprosium, holmium and erbium in several rare earth. (author). 9 refs, 2 figs, 2 tabs

  13. Creating high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses

    Xin, PeiPei; Cheng, Hong; Zhang, ShanShan; Wang, HanMu; Xu, ZiShan; Liu, HongPing

    2018-04-01

    We propose a method of producing high-purity angular-momentum-state Rydberg atoms by a pair of unipolar laser pulses. The first positive-polarity optical half-cycle pulse is used to prepare an excited-state wave packet while the second one is less intense, but with opposite polarity and time delayed, and is employed to drag back the escaping free electron and clip the shape of the bound Rydberg wave packet, selectively increasing or decreasing a fraction of the angular-momentum components. An intelligent choice of laser parameters such as phase and amplitude helps us to control the orbital-angular-momentum composition of an electron wave packet with more facility; thus, a specified angular-momentum state with high purity can be achieved. This scheme of producing high-purity angular-momentum-state Rydberg atoms has significant application in quantum-information processing.

  14. Measurement of glomerular filtration rate using technetium-99m-DTPA and the gamma camera: A comparison of methods

    Russell, C.D.; Bischoff, P.G.; Kontzen, F.; Rowell, K.L.; Yester, M.V.; Lloyd, L.K.; Tauxe, W.N.; Dubovsky, E.V.

    1984-01-01

    A variety of methods has been proposed to estimate glomerular filtration rate (GFR) from renal uptake of Tc-99m-DTPA using a gamma camera. To compare alternative methods, the authors have calculated GFR in several different ways from measurements in 33 patients, and compared the results with an independent GFR measurement based on 8-point plasma clearance of Yb-169-DTPA. The best agreement was obtained using an algorithm that has not been described previously. This was a modification of a method used previously in which correction was made for overlap of kidneys by liver and spleen. The correlation coefficient was 0.958 and the residual standard deviation was 12.1 ml/min. This method required a single 20-min blood sample as well as the camera data. The best method not requiring a blood sample was significantly less accurate, with correlation coefficient 0.866 and residual standard deviation 21.1 ml/min. The accuracy of these methods was comparable to that reported for the creatinine clearance, the most commonly used estimate of GFR in current clinical practice

  15. Reliability of single kidney glomerular filtration rate measured by a 99mTc-DTPA gamma camera technique

    Rehling, M.; Moller, M.L.; Jensen, J.J.; Thamdrup, B.; Lund, J.O.; Trap-Jensen, J.

    1986-01-01

    The reliability of a previously published method for determination of single kidney glomerular filtration rate (SKGFR) by means of technetium-99m-diethylenetriaminepenta-acetate (99mTc-DTPA) gamma camera renography was evaluated. The day-to-day variation in the calculated SKGFR values was earlier found to be 8.8%. The technique was compared to the simultaneously measured renal clearance of inulin in 19 unilaterally nephrectomized patients with GFR varying from 11 to 76 ml/min. The regression line (y = 1.04 X -2.5) did not differ significantly from the line of identity. The standard error of estimate was 4.3 ml/min. In 17 patients the inter- and intraobserver variation of the calculated SKGFR values was 1.2 ml/min and 1.3 ml/min, respectively. In 21 of 25 healthy subjects studied (age range 27-29 years), total GFR calculated from the renograms was within an established age-dependent normal range of GFR

  16. Non-invasive estimation of the human pulmonary blood volume with gamma camera and RI-angiocardiography

    Goto, Koshi; Hirano, Akihiko; Hirakawa, Senri

    1981-01-01

    A new, non-invasive method for the estimation of the human pulmonary blood volume (PBV), existing between the pulmonary artery bifurcation (PAB) and the left atrium (LA), has been developed in this laboratory, in the form of PBV = PPT sub(RCG) x 0.77 x CO, equation (6), given in Appendix. This was an extension of the classical Stewart-Hamilton method of indicator dilution, applied to radioisotope angiocardiography. Using a gamma-camera, the radio-isotope (99 m Tc-albumin) dilution curves were recorded externally at the region of PAB, LA and LV (left ventricle), among other things, in human subjects in supine position. The mean transit time (MTT) was determined for each region, and the difference in MTT, e.g., ΔMTT sub(PAB-LA), was measured. We calculated PBV between PAB and LA as PBV = ΔMTT sub(PAB-LA) x CO, equation (1) given in Appendix. Empirical time relations between ΔMTT sub(PAB-LA) and PPT sub(RCG) were examined in mechanical models and human subjects, through several steps represented by equations (2) to (5), given in Appendix, and our tentatively final formula was equation (6). The values of PBV estimated in this way were in good agreement with those of PBV measured invasively in the past, using two injection sites (PA and LA) and one sampling site (artery). (author)

  17. Simulation-based evaluation and optimization of a new CdZnTe gamma-camera architecture (HiSens)

    Robert, Charlotte; Montemont, Guillaume; Rebuffel, Veronique; Guerin, Lucie; Verger, Loick; Buvat, Irene

    2010-01-01

    A new gamma-camera architecture named HiSens is presented and evaluated. It consists of a parallel hole collimator, a pixelated CdZnTe (CZT) detector associated with specific electronics for 3D localization and dedicated reconstruction algorithms. To gain in efficiency, a high aperture collimator is used. The spatial resolution is preserved thanks to accurate 3D localization of the interactions inside the detector based on a fine sampling of the CZT detector and on the depth of interaction information. The performance of this architecture is characterized using Monte Carlo simulations in both planar and tomographic modes. Detective quantum efficiency (DQE) computations are then used to optimize the collimator aperture. In planar mode, the simulations show that the fine CZT detector pixelization increases the system sensitivity by 2 compared to a standard Anger camera without loss in spatial resolution. These results are then validated against experimental data. In SPECT, Monte Carlo simulations confirm the merits of the HiSens architecture observed in planar imaging.

  18. Functional studies of the oesophagus with sulfur-colloid of sup(99m)Tc and gamma-camera

    Veiga-Fernandes, F.; Costa, P.M.; Pinheiro, M.F.; Guerreiro, D.

    1982-01-01

    A scintiscanning technique which allows sequential detection and quantification of gastro-oesophageal reflux (GER), and study of the oesophageal emptying of a liquid and semi-solid food is presented. At first patients swallowed 5 ml of water containing 1 mCi sup(99m)Tc sulfur-colloid and oesophageal activity is recorded from an anterior view by a gamma-camera. Then, patients ingest 300 ml of water that clear the oesophagus and fill up the stomach. GER index is calculated according to the formula GER = (Ae - Ab)/Ag) x 100, where Ae is the activity in the oesophagus; Ab, is the background activity; and Ag is the gastric activity. GER index presented corresponds to a median of three determinations in upright, supine and supine position with abdominal pressure of 4 kilos. The oesophageal transit time of a semi-solid food in upright and supine position is registered 5 minutes after GER studies through two areas of interest which are positioned: one in the superior third and the other in the inferior third of the oesophagus. Normal GER reflux index was, 0.84 +- 0.37 in the upright position; 0.87 +- 0.43 in the supine position; and 0.90 +- 0.56 in the supine position plus abdominal pressure

  19. Simulation of a multi-detector gamma camera for validation protocols of quantification the activity from SPECT images

    Lozano Sanchez, A.; Calderon Marin, C.; Gonzalez Gonzalez, J.

    2015-01-01

    The main sources that decreasing accuracy in the estimation of internal absorbed dose has been identified in the methods for the quantification of cumulated activity from scintigraphic imaging, likes the corrections required by the physical and instrumental phenomena related to the formation of those images. The results of the simulation of a dual detector gamma camera E.cam SIEMENS using the Monte Carlo code SIMIND to obtain tomographic SPECT projections are presented here. SIMIND will allow dealing with the contribution of physical interactions and instrumental effects during simulations. Energy resolution, spatial resolution and sensitivity planar were determined with real and simulated systems. The relative differences did not exceed 10%. Energy spectra simulated under different conditions (source in air and water) with the inclusion of interactions in the collimator and phantom were compared. The tomographic sensitivity of a volumetric phantom containing radioactive solutions of 99m Tc and 131 I were determined from real and simulated SPECT images. Two processing protocols were considered: with scatter correction ( 99m Tc dual energy window method and 131 I were calculated after corrections. The results, expressed in terms of the differences relative to the well-know activity value in the phantom inserts improves when attenuation and scattering corrections are applied, obtaining good agreement between the results for real and simulated systems. (Author)

  20. Assessment of spleen size using gamma camera scintigraphy in newly diagnosed patients with essential thrombocythaemia and polycythaemia vera

    Carneskog, J.; Wadenvik, H.; Kutti, J.; Fjaeelling, M.

    1996-01-01

    By using gamma camera imaging the spleen size was assessed in 18 consecutive patients with essential thrombocythaemia (ET) and in 18 consecutive patients with polycythaemia vera (PV). All ET and PV patients were newly diagnosed and had not received any myelosuppressive therapy prior to study. The spleen areas in both posterior and left lateral projections were determined. Eighteen consecutive patients with idiopathic thrombocytopenic purpura (ITP) served as a control group since by definition they do not present with splenic enlargement; in these latter subjects the mean posterior and left lateral splenic areas were almost identical (48 ± 15 and 47 ± 17 cm 2 , respectively). In comparison with this control group patients with ET an dPV had significantly larger spleens. In both ET and in PV patients the left lateral spleen scan area exceeded the posterior one. Patients with PV had larger splenic areas in both projections than did patients with ET, but the differences were not statistically significant. Compared to the ITP patients it was found that at least 50% of the ET patients and at least 61% of the PV patients at diagnosis presented with splenomegaly. (au) 35 refs

  1. Assessment of spleen size using gamma camera scintigraphy in newly diagnosed patients with essential thrombocythaemia and polycythaemia vera

    Carneskog, J.; Wadenvik, H.; Kutti, J. [Univ. of Goeteborg, Sahlgrenska Univ. Hospital, Dept. of Medicine, Haematology Section, Goeteborg (Sweden); Fjaeelling, M. [Univ. of Goeteborg, Sahlgrenska Univ. Hospital, Dept. of Clinical Physiology, Section of Nuclear Med., Goeteborg (Sweden)

    1996-03-01

    By using gamma camera imaging the spleen size was assessed in 18 consecutive patients with essential thrombocythaemia (ET) and in 18 consecutive patients with polycythaemia vera (PV). All ET and PV patients were newly diagnosed and had not received any myelosuppressive therapy prior to study. The spleen areas in both posterior and left lateral projections were determined. Eighteen consecutive patients with idiopathic thrombocytopenic purpura (ITP) served as a control group since by definition they do not present with splenic enlargement; in these latter subjects the mean posterior and left lateral splenic areas were almost identical (48 {+-} 15 and 47 {+-} 17 cm{sup 2}, respectively). In comparison with this control group patients with ET an dPV had significantly larger spleens. In both ET and in PV patients the left lateral spleen scan area exceeded the posterior one. Patients with PV had larger splenic areas in both projections than did patients with ET, but the differences were not statistically significant. Compared to the ITP patients it was found that at least 50% of the ET patients and at least 61% of the PV patients at diagnosis presented with splenomegaly. (au) 35 refs.

  2. Intraoperative Scintigraphy Using a Large Field-of-View Portable Gamma Camera for Primary Hyperparathyroidism: Initial Experience

    Nathan C. Hall

    2015-01-01

    Full Text Available Background. We investigated a novel technique, intraoperative 99 mTc-Sestamibi (MIBI imaging (neck and excised specimen (ES, using a large field-of-view portable gamma camera (LFOVGC, for expediting confirmation of MIBI-avid parathyroid adenoma removal. Methods. Twenty patients with MIBI-avid parathyroid adenomas were preoperatively administered MIBI and intraoperatively imaged prior to incision (neck and immediately following resection (neck and/or ES. Preoperative and intraoperative serum parathyroid hormone monitoring (IOPTH and pathology (path were also performed. Results. MIBI neck activity was absent and specimen activity was present in 13/20 with imaging after initial ES removal. In the remaining 7/20 cases, residual neck activity and/or absent ES activity prompted excision of additional tissue, ultimately leading to complete hyperfunctioning tissue excision. Postexcision LFOVGC ES imaging confirmed parathyroid adenoma resection 100% when postresection imaging qualitatively had activity (ES and/or no activity (neck. The mean ± SEM time saving using intraoperative LFOVGC data to confirm resection versus first IOPTH or path result would have been 22.0 ± 2 minutes (specimen imaging and 26.0 ± 3 minutes (neck imaging. Conclusion. Utilization of a novel real-time intraoperative LFOVGC imaging approach can provide confirmation of MIBI-avid parathyroid adenoma removal appreciably faster than IOPTH and/or path and may provide a valuable adjunct to parathyroid surgery.

  3. Iterative reconstruction of SiPM light response functions in a square-shaped compact gamma camera

    Morozov, A.; Alves, F.; Marcos, J.; Martins, R.; Pereira, L.; Solovov, V.; Chepel, V.

    2017-05-01

    Compact gamma cameras with a square-shaped monolithic scintillator crystal and an array of silicon photomultipliers (SiPMs) are actively being developed for applications in areas such as small animal imaging, cancer diagnostics and radiotracer guided surgery. Statistical methods of position reconstruction, which are potentially superior to the traditional centroid method, require accurate knowledge of the spatial response of each photomultiplier. Using both Monte Carlo simulations and experimental data obtained with a camera prototype, we show that the spatial response of all photomultipliers (light response functions) can be parameterized with axially symmetric functions obtained iteratively from flood field irradiation data. The study was performed with a camera prototype equipped with a 30  ×  30  ×  2 mm3 LYSO crystal and an 8  ×  8 array of SiPMs for 140 keV gamma rays. The simulations demonstrate that the images, reconstructed with the maximum likelihood method using the response obtained with the iterative approach, exhibit only minor distortions: the average difference between the reconstructed and the true positions in X and Y directions does not exceed 0.2 mm in the central area of 22  ×  22 mm2 and 0.4 mm at the periphery of the camera. A similar level of image distortions is shown experimentally with the camera prototype.

  4. The germination of germanium

    Burdette, Shawn C.; Thornton, Brett F.

    2018-02-01

    Shawn C. Burdette and Brett F. Thornton explore how germanium developed from a missing element in Mendeleev's periodic table to an enabler for the information age, while retaining a nomenclature oddity.

  5. Human parvovirus B19 infection in hemophiliacs first infused with two high-purity, virally attenuated factor VIII concentrates.

    Azzi, A; Ciappi, S; Zakvrzewska, K; Morfini, M; Mariani, G; Mannucci, P M

    1992-03-01

    Human parvovirus B19 can be transmitted by coagulation factor concentrates and is highly resistant to virucidal methods. To evaluate whether the additional removal of virus by chromatographic methods during the manufacture of high-purity concentrates reduces the risk of B19 transmission, we have prospectively evaluated the rate of anti-B19 seroconversion in two groups of susceptible (anti-B19 negative) hemophiliacs infused with high-purity, heated (pasteurized) or solvent-detergent-treated factor VIII concentrates. Both products infected a relatively high proportion of patients (nine of 20).

  6. Angiocardiography with 99mTc-albumin bymass of gamma camera associated with examinations in the morphological and dynamic study of the congenital heart disease

    Esposti, A D; Abbati, A

    1975-03-03

    A. Degli Esposti and A. Abbati: Computerised gamma-camera 99/sup m/ Tc-albumin angiocardiography in the morphological and dynamic examination of children with congenital heart disease. A number of cases in which computerised gamma-camera 99/sup m/ Tc-albumin angiocardiography was employed in children with congenital heart diseases are described. Comparison is made with the data obtained contrastographically, or during surgery or necropsy. The preliminary results, particularly in recently examined subjects, whose data were processed in a more efficient manner, point to the usefulness of the method. Though incapable of offering the same morphological precision as contrastography, it has the advantage of being absolute harmless and, above all, repeatable.

  7. Abridged acid-base wet-milling synthesis of high purity hydroyapatite

    Sandi Carolina Ruiz-Mendoza

    2008-06-01

    Full Text Available There is a plethora of routes to produce hydroxyapatite(HA and in general calcium phosphates(CP but production usually leads to a mixture of several phases. Besides ionic contamination, most of these methods are cumbersome, restricted to small volumes of product and require a lot of thermal energy. The acid-base route eliminates foreign ions or additives and its only byproduct is water. Heterogeneous reaction drawback is that solid reactants do not easily come in contact with each other and therefore addition and stirring times become very lengthy and still the product is a mixture. The synthesis started from calcium hydroxide and phosphoric acid (PA. Ball milling was used to favor kinetics and stoichiometry. Six sets of PA addition, paddle stirring and ball milling times were used. Products were evaluated by X ray diffraction (XRD, Fourier Transform Infrared (FTIR, scanning electron microscopy (SEM, X ray fluorescence (XRF and Ca/P ratio. Chemical analysis for calcium proceeded through oxalate precipitate and phosphorus by the phosphomolibdate technique. A set of conditions yielding high purity HA was established.

  8. Characteristics of high-purity Teflon vial for 14C measurement in old tree rings

    Sakurai, H.; Saswaki, Y.; Matsumoto, T.; Aoki, T.; Kato, W.; Gandou, T.; Gunji, S.; Tokanai, F.

    2003-01-01

    14 C concentration in single-year tree rings of an old cedar of ca. 2500 years ago is measured to investigate the 11-yr periodicity of solar activity. Our highly accurate 14 C measuring system is composed of a benzene synthesizer capable of producing a large quantity (10 g) of benzene and a Quantulus 1220 TM liquid scintillation counting system. The accuracy is less than 0.2% for measurements of 14 C concentration. The benzene sample is contained in a high-purity Teflon/copper-counting vial (20 ml) manufactured by Wallac Oy Company. We found a vial with an irregular copper cap for the measurements of 11 tree rings. The behavior of the vial with the irregular cap was investigated. The Teflon sheet inside the cap plays an important role in achieving stable measurement. The rate of volatilization of the benzene was less than 0.35 mg/day for vials with ordinary caps. This results in the volatilization rate of 0.003% for 10.5 g of benzene and hence guarantees measurement at an accuracy of 0.2% for 70 days

  9. Comparison of the effect of neutron irradiation on high purity vanadium and vanadium oxygen alloys

    Arsenault, R.J.; Bressers, J.

    1977-01-01

    An investigation of the effect of neutron damage on the low temperature deformation characteristics of high purity vanadium (R/sub 300K//R/sub 4.2K/ = 1100) was undertaken for two purposes. One purpose was to determine if reducing the purity interstitial content to a lower level would result in a large difference in the effective stress between irradiated and non-irradiated samples. The present data along with previously obtained data does indicate that the difference increases as the impurity interstitial content is reduced. The explanation of this observation is based on the rapid increase of the non-irradiated yield stress at 77 0 K due to small increases in the oxygen content; however, the increase of the yield stress of the irradiated samples is much less with the same increase in oxygen content. A second purpose of this investigation was to determine the size and density of observable neutron produced defects as a function of oxygen content by transmission electron microscopy, and to relate the changes in density with changes in the yield stress. It was found that the density decreases and the size increases as the oxygen content decreases. There is qualitative agreement between the increase in yield stress at 300 0 K and the observable defect density. However, the change in the yield stress at 77 0 K due to neutron irradiation cannot be related to defect density and size

  10. Electrical properties of as-grown and proton-irradiated high purity silicon

    Krupka, Jerzy, E-mail: krupka@imio.pw.edu.pl [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Karcz, Waldemar [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation); Kamiński, Paweł [Institute of Electronic Materials Technology, Wólczyńska 13, 301-919 Warsaw (Poland); Jensen, Leif [Topsil Semiconductor Materials A/S, Siliciumvej 1, DK-3600 Frederikssund (Denmark)

    2016-08-01

    The complex permittivity of as-grown and proton-irradiated samples of high purity silicon obtained by the floating zone method was measured as a function of temperature at a few frequencies in microwave spectrum by employing the quasi TE{sub 011} and whispering gallery modes excited in the samples under test. The resistivity of the samples was determined from the measured imaginary part of the permittivity. The resistivity was additionally measured at RF frequencies employing capacitive spectroscopy as well as in a standard direct current experiment. The sample of as-grown material had the resistivity of ∼85 kΩ cm at room temperature. The sample irradiated with 23-MeV protons had the resistivity of ∼500 kΩ cm at 295 K and its behavior was typical of the intrinsic material at room and at elevated temperatures. For the irradiated sample, the extrinsic conductivity region is missing and at temperatures below 250 K hopping conductivity occurs. Thermal cycle hysteresis of the resistivity for the sample of as-grown material is observed. After heating and subsequent cooling of the sample, its resistivity decreases and then slowly (∼50 h) returns to the initial value.

  11. GELATIO: a general framework for modular digital analysis of high-purity Ge detector signals

    Agostini, M; Pandola, L; Zavarise, P; Volynets, O

    2011-01-01

    GELATIO is a new software framework for advanced data analysis and digital signal processing developed for the GERDA neutrinoless double beta decay experiment. The framework is tailored to handle the full analysis flow of signals recorded by high purity Ge detectors and photo-multipliers from the veto counters. It is designed to support a multi-channel modular and flexible analysis, widely customizable by the user either via human-readable initialization files or via a graphical interface. The framework organizes the data into a multi-level structure, from the raw data up to the condensed analysis parameters, and includes tools and utilities to handle the data stream between the different levels. GELATIO is implemented in C++. It relies upon ROOT and its extension TAM, which provides compatibility with PROOF, enabling the software to run in parallel on clusters of computers or many-core machines. It was tested on different platforms and benchmarked in several GERDA-related applications. A stable version is presently available for the GERDA Collaboration and it is used to provide the reference analysis of the experiment data.

  12. Interaction between a high purity magnesium surface and PCL and PLA coatings during dynamic degradation

    Chen Ying; Song Yang; Zhang Shaoxiang; Li Jianan; Zhao Changli; Zhang Xiaonong

    2011-01-01

    In this study, polycaprolactone (PCL) and polylactic acid (PLA) coatings were prepared on the surface of high purity magnesium (HPMs), respectively, and electrochemical and dynamic degradation tests were used to investigate the degradation behaviors of these polymer-coated HPMs. The experimental results indicated that two uniform and smooth polymer films with thicknesses between 15 and 20 μm were successfully prepared on the HPMs. Electrochemical tests showed that both PCL-coated and PLA-coated HPMs had higher free corrosion potentials (E corr ) and smaller corrosion currents (I corr ) in the modified simulated body fluid (m-SBF) at 37 0 C, compared to those of the uncoated HPMs. Dynamic degradation tests simulating the flow conditions in coronary arteries were carried out on a specific test platform. The weight of the specimens and the pH over the tests were recorded to characterize the corrosion performance of those samples. The surfaces of the specimens after the dynamic degradation tests were also examined. The data implied that there was a special interaction between HPM and its polymer coatings during the dynamic degradation tests, which undermined the corrosion resistance of the coated HPMs. A model was proposed to illustrate the interaction between the polymer coatings and HPM. This study also suggested that this reciprocity may also exist on the implanted magnesium stents coated with biodegradable polymers, which is a potential obstacle for the further development of drug-eluting magnesium stents.

  13. Determination of trace impurities in high purity water by emission spectroscopy and flame photometry

    Charbel, M.Y.; Lordello, A.R.

    1985-01-01

    A spectrochemical method for the determination of trace amounts of Fe, Mg, Mn, Sn, Cr, Bi, Ni, Ca, Na, Zn, Sr, Al, Ba and Cu in high purity water is described. In addition Na, Li and K are measured by flame photometry. The standards used in the spectrochemical method are prepared by evaporation in hot plate of 50 mL standard solution in Teflon becker to dryness, the residue being dissolved with 500 μL hot HCl (1:1). Four hundred μL of this solution is evaporated under infra-red lamp on Apiezon treated flat top graphite electrodes. The residue is submitted to a direct current arc excitation. The accuracy is estimated by the spectrochemical method with a direct procedure sample preparation. The relative standard deviation varies from +- 4% to +- 27%. For the elements Na, Li and K standard solutions are concentrated fiftyfold by a simple evaporation procedure and then measured by flame photometry. The standard deviation and accuracy are given. (Author) [pt

  14. Micro-deformation behavior in micro-compression with high-purity aluminum processed by ECAP

    Xu Jie

    2015-01-01

    Full Text Available Ultrafine-grained (UFG materials have a potential for applications in micro-forming since grain size appears to be the dominant factor which determines the limiting size of the geometrical features. In this research, high-purity Al was processed by equal-channel angular pressing (ECAP at room temperature through 1–8 passes. Analysis shows that processing by ECAP produces a UFG structure with a grain size of ~1.3 μm and with microhardness and microstructural homogeneity. Micro-compression testing was carried out with different specimen dimensions using the annealed sample and after ECAP processing through 1–8 passes. The results show the flow stress increases significantly after ECAP processing by comparison with the annealed material. The flow stress generally reaches a maximum value after 2 passes which is consistent with the results of microhardness. The flow stress decreases with decreasing specimen diameter from 4 mm to 1 mm which demonstrates that size effects also exist in the ultrafine-grained materials. However, the deformation mechanism in ultrafine-grained pure Al changes from strain strengthening to softening by dynamic recovery by comparison with the annealed material.

  15. Native oxidation of ultra high purity Cu bulk and thin films

    Iijima, J.; Lim, J.-W.; Hong, S.-H.; Suzuki, S.; Mimura, K.; Isshiki, M.

    2006-01-01

    The effect of microstructure and purity on the native oxidation of Cu was studied by using angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and spectroscopic ellipsometry (SE). A high quality copper film prepared by ion beam deposition under a substrate bias voltage of -50 V (IBD Cu film at V s = -50 V) showed an oxidation resistance as high as an ultra high purity copper (UHP Cu) bulk, whereas a Cu film deposited without substrate bias voltage (IBD Cu film at V s = 0 V) showed lower oxidation resistance. The growth of Cu 2 O layer on the UHP Cu bulk and both types of the films obeyed in principle a logarithmic rate law. However, the growth of oxide layer on the IBD Cu films at V s = 0 and -50 V deviated upward from the logarithmic rate law after the exposure time of 320 and 800 h, respectively. The deviation from the logarithmic law is due to the formation of CuO on the Cu 2 O layer after a critical time

  16. Synthesis of high purity rutile nanoparticles from medium-grade Egyptian natural ilmenite

    Mohamed G. Shahien

    2015-09-01

    Full Text Available The Egyptian magmatic ilmenite is classified as a medium-grade ore. The present work is an attempt to produce a high-quality TiO2 that can be used in several industries from this medium-grade raw material using the mechanical activation, carbothermic reduction, hydrochloric acid leaching and calcination. A mixture from the ilmenite (FeTiO3 and activated carbon was milled for 30 h. This mixture was annealed at 1200 °C for one hour and the product was leached by hydrochloric acid and calcined at 600 °C for two hours. The role of the ball milling was to grind the raw ilmenite to obtain the nano size, and the carbothermic reduction was to reduce all the Fe-Ti phases to a mixture from Fe metal and TiO2. Leaching procedure was carried out to remove all the Fe metal and obtain a high-grade TiO2. After leaching and calcination of the milled and annealed mixture of FeTiO3/C under the optimal conditions, TiO2 nanoparticles with a size of 10–100 nm and purity more than 95% were obtained. The qualifications of the synthesized high purity rutile nanoparticles from the Egyptian natural ilmenite match the conditions of many industrial applications.

  17. Comparison between bulk and thin foil ion irradiation of ultra high purity Fe

    Prokhodtseva, A., E-mail: anna.prokhodtseva@psi.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, 5232 Villigen PSI (Switzerland); Décamps, B. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), CNRS-IN2P3-Univ. Paris-Sud 11, UMR 8609, Bât. 108, 91405 Orsay (France); Schäublin, R. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, 5232 Villigen PSI (Switzerland)

    2013-11-15

    Accumulation of radiation damage in ultra high purity iron under self ion irradiation without and with simultaneous He implantation was investigated in bulk and thin foil form to assess, on the one hand, the effect of free surfaces and, on the other hand, the influence of He. Specimens were irradiated at room temperature to a dose of 0.8 dpa and ∼900 appm He content. We found in thin foils after irradiation with single beam a majority of a{sub 0} 〈1 0 0〉 type loops, while in the presence of He it is the ½ a{sub 0} 〈1 1 1〉 type loops that prevail. In single beam irradiated bulk samples most of the loops are of ½ a{sub 0} 〈1 1 1〉 type. In both bulk and thin foils density of defects visible in transmission electron microscope is considerably higher when He is implanted with prevailing ½ a{sub 0} 〈1 1 1〉 dislocation loops, indicating that He stabilizes them.

  18. Effect of temperature on corrosion of steels in high purity water

    Honda, Takashi; Kashimura, Eiji; Ohashi, Kenya; Furutani, Yasumasa; Ohsumi, Katsumi; Aizawa, Motohiro; Matsubayashi, Hideo.

    1987-01-01

    Effect of temperature on corrosion behavior of steels was evaluated in the range of 150 - 300 deg C in high purity water containing about 200 ppb oxygen. The exposure tests were carried out in actual and simulated reactor water of BWR plants. Through X-ray diffractometry, SIMS, XPS and chemical analyses, it was clarified that the chemical composition and morphology of oxide films formed on austenitic stainless steel changed above about 250 deg C. Chromium dissolved easily through corrosion above this temperature, and the oxide films primarily consisted of spinel type oxides containing high concentration of nickel. Further, as the protectivety of oxide films increased with temperature, the corrosion rate had a peak around 250 deg C after a long exposure period. A major phase of oxide films on carbon steel was magnetite in the whole temperature range. However, as the oxide films formed at high temperatures had very compact structures, the effect of temperature on the corrosion rate was similar to that observed on stainless steel. (author)

  19. Radio frequency and linearity performance of transistors using high-purity semiconducting carbon nanotubes.

    Wang, Chuan; Badmaev, Alexander; Jooyaie, Alborz; Bao, Mingqiang; Wang, Kang L; Galatsis, Kosmas; Zhou, Chongwu

    2011-05-24

    This paper reports the radio frequency (RF) and linearity performance of transistors using high-purity semiconducting carbon nanotubes. High-density, uniform semiconducting nanotube networks are deposited at wafer scale using our APTES-assisted nanotube deposition technique, and RF transistors with channel lengths down to 500 nm are fabricated. We report on transistors exhibiting a cutoff frequency (f(t)) of 5 GHz and with maximum oscillation frequency (f(max)) of 1.5 GHz. Besides the cutoff frequency, the other important figure of merit for the RF transistors is the device linearity. For the first time, we report carbon nanotube RF transistor linearity metrics up to 1 GHz. Without the use of active probes to provide the high impedance termination, the measurement bandwidth is therefore not limited, and the linearity measurements can be conducted at the frequencies where the transistors are intended to be operating. We conclude that semiconducting nanotube-based transistors are potentially promising building blocks for highly linear RF electronics and circuit applications.

  20. Recovery of high-purity metallic Pd from Pd(II)-sorbed biosorbents by incineration.

    Won, Sung Wook; Lim, Areum; Yun, Yeoung-Sang

    2013-06-01

    This work reports a direct way to recover metallic palladium with high purity from Pd(II)-sorbed polyethylenimine-modified Corynebacterium glutamicum biosorbent using a combined method of biosorption and incineration. This study is focused on the incineration part which affects the purity of recovered Pd. The incineration temperature and the amount of Pd loaded on the biosorbent were considered as major factors in the incineration process, and their effects were examined. The results showed that both factors significantly affected the enhancement of the recovery efficiency and purity of the recovered Pd. SEM-EDX and XRD analyses were used to confirm that Pd phase existed in the ash. As a result, the recovered Pd was changed from PdO to zero-valent Pd as the incineration temperature was increased from 600 to 900°C. Almost 100% pure metallic Pd was recovered with recovery efficiency above 99.0% under the conditions of 900°C and 136.9 mg/g. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Modelling of hydrogen permeability of membranes for high-purity hydrogen production

    Zaika, Yury V.; Rodchenkova, Natalia I.

    2017-11-01

    High-purity hydrogen is required for clean energy and a variety of chemical technology processes. Different alloys, which may be well-suited for use in gas-separation plants, were investigated by measuring specific hydrogen permeability. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones), and identify the limiting factors. This paper presents a nonlinear mathematical model taking into account the dynamics of sorption-desorption processes and reversible capture of diffusing hydrogen by inhomogeneity of the material’s structure, and also modification of the model when the transport rate is high. The results of numerical modelling allow to obtain information about output data sensitivity with respect to variations of the material’s hydrogen permeability parameters. Furthermore, it is possible to analyze the dynamics of concentrations and fluxes that cannot be measured directly. Experimental data for Ta77Nb23 and V85Ni15 alloys were used to test the model. This work is supported by the Russian Foundation for Basic Research (Project No. 15-01-00744).

  2. Recovery of high purity proteins from polyacrylamide gels using ultraviolet scanning densitometry

    Bartolini, P.; Arkaten, R.; Ribela, M.T.C.P.

    1988-07-01

    We present here a technique for the purification of proteins carried out by a quantitative analytical method used in conjunction with a preparative gel electrophoresis. Both methods employ densitometric ultraviolet scanning of unstained protein bands, a procedure wich is particulary suitable for the purification and recovery of biologically active polypeptides. In short, the purified extracted protein, isolated in a segment cut out from a preparative gel, is recovered by a second (reversed) electrophoresis. We performed the extractions and recoveries of different amounts of two standard proteins (BSA and STI) and a polypeptide hormone (hGH). Our main interest, especially for the hormone is the complete protein recovery with retention of bio and immunoactivity and high purity. For the proteins tested, the mean recovery was of 93 + - 5% obtaining a mean purity of 95 + - 7%. We conclude that the proposed method should have interesting applications, particularly in the obtention of very pure hormones, as are needed for radioligand assays, for radiolabelling and specific antibody raising. We emphasize the simplicity and rapidity of the method (the entire preparative process: first electrophoresis, UV scanning and reversed electrophoresis can be performed in approximately six hours) and its efficiency in recovering pure proteins even on a milligram scale. We thank the support from the IAEA (4299/RB) and FINEP (43.86.0351.00) and CENE (Brazil). (author) [pt

  3. Research of a novel biodegradable surgical staple made of high purity magnesium

    Hongliu Wu

    2016-12-01

    Full Text Available Surgical staples made of pure titanium and titanium alloys are widely used in gastrointestinal anastomosis. However the Ti staple cannot be absorbed in human body and produce artifacts on computed tomography (CT and other imaging examination, and cause the risk of incorrect diagnosis. The bioabsorbable staple made from polymers that can degrade in human body environment, is an alternative. In the present study, biodegradable high purity magnesium staples were developed for gastric anastomosis. U-shape staples with two different interior angles, namely original 90° and modified 100°, were designed. Finite element analysis (FEA showed that the residual stress concentrated on the arc part when the original staple was closed to B-shape, while it concentrated on the feet for the modified staple after closure. The in vitro tests indicated that the arc part of the original staple ruptured firstly after 7 days immersion, whereas the modified one kept intact, demonstrating residual stress greatly affected the corrosion behavior of the HP-Mg staples. The in vivo implantation showed good biocompatibility of the modified Mg staples, without inflammatory reaction 9 weeks post-operation. The Mg staples kept good closure to the Anastomosis, no leaking and bleeding were found, and the staples exhibited no fracture or severe corrosion cracks during the degradation.

  4. Precise coulometric titration of uranium in a high-purity uranium metal and in uranium compounds

    Tanaka, Tatsuhiko; Yoshimori, Takayoshi

    1975-01-01

    Uranium in uranyl nitrate, uranium trioxide and a high-purity uranium metal was assayed by the coulometric titration with biamperometric end-point detection. Uranium (VI) was reduced to uranium (IV) by solid bismuth amalgam in 5M sulfuric acid solution. The reduced uranium was reoxidized to uranium (VI) with a large excess of ferric ion at a room temperature, and the ferrous ion produced was titrated with the electrogenerated manganese(III) fluoride. In the analyses of uranium nitrate and uranium trioxide, the results were precise enough when the error from uncertainty in water content in the samples was considered. The standard sample of pure uranium metal (JAERI-U4) was assayed by the proposed method. The sample was cut into small chips of about 0.2g. Oxides on the metal surface were removed by the procedure shown by National Bureau of Standards just before weighing. The mean assay value of eleven determinations corrected for 3ppm of iron was (99.998+-0.012) % (the 95% confidence interval for the mean), with a standard deviation of 0.018%. The proposed coulometric method is simple and permits accurate and precise determination of uranium which is matrix constituent in a sample. (auth.)

  5. GELATIO: a general framework for modular digital analysis of high-purity Ge detector signals

    Agostini, M.; Pandola, L.; Zavarise, P.; Volynets, O.

    2011-08-01

    GELATIO is a new software framework for advanced data analysis and digital signal processing developed for the GERDA neutrinoless double beta decay experiment. The framework is tailored to handle the full analysis flow of signals recorded by high purity Ge detectors and photo-multipliers from the veto counters. It is designed to support a multi-channel modular and flexible analysis, widely customizable by the user either via human-readable initialization files or via a graphical interface. The framework organizes the data into a multi-level structure, from the raw data up to the condensed analysis parameters, and includes tools and utilities to handle the data stream between the different levels. GELATIO is implemented in C++. It relies upon ROOT and its extension TAM, which provides compatibility with PROOF, enabling the software to run in parallel on clusters of computers or many-core machines. It was tested on different platforms and benchmarked in several GERDA-related applications. A stable version is presently available for the GERDA Collaboration and it is used to provide the reference analysis of the experiment data.

  6. A solvent-extraction module for cyclotron production of high-purity technetium-99m.

    Martini, Petra; Boschi, Alessandra; Cicoria, Gianfranco; Uccelli, Licia; Pasquali, Micòl; Duatti, Adriano; Pupillo, Gaia; Marengo, Mario; Loriggiola, Massimo; Esposito, Juan

    2016-12-01

    The design and fabrication of a fully-automated, remotely controlled module for the extraction and purification of technetium-99m (Tc-99m), produced by proton bombardment of enriched Mo-100 molybdenum metallic targets in a low-energy medical cyclotron, is here described. After dissolution of the irradiated solid target in hydrogen peroxide, Tc-99m was obtained under the chemical form of 99m TcO 4 - , in high radionuclidic and radiochemical purity, by solvent extraction with methyl ethyl ketone (MEK). The extraction process was accomplished inside a glass column-shaped vial especially designed to allow for an easy automation of the whole procedure. Recovery yields were always >90% of the loaded activity. The final pertechnetate saline solution Na 99m TcO 4 , purified using the automated module here described, is within the Pharmacopoeia quality control parameters and is therefore a valid alternative to generator-produced 99m Tc. The resulting automated module is cost-effective and easily replicable for in-house production of high-purity Tc-99m by cyclotrons. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Effect of microplastic deformation on the electron ultrasonic absorption in high-purity molybdenum monocrystals

    Pal' -Val' , P.P. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur); Kaufmann, Kh.J. (Akademie der Wissenschaften der DDR, Berlin)

    1983-03-01

    The low temperature (100-6 K) linear absorption of ultrasound (88 kHz) by high purity molybdenum single crystals have been studied. Both unstrained samples and samples subjected to microplastic deformation (epsilon<=0.45%) were used. Unstrained samples displayed at T<30 K a rapid increase in the absorption with lowering temperature which is interpreted as an indication of electron viscosity due to electron-phonon collisions. After deformation this part of absorption disappeared. This seems to suggest that microplastic deformation brings about in the crystal a sufficiently large number of defects that can compete with phonons in restricting the electron mean free path. A low temperature ''dynamic annealing'' has been revealed in strained samples, that is, almost complete recovery of the absorption nature under irradiation with high amplitude sound, epsilon/sub 0/ approximately 10/sup -4/, during 10 min, at 6 K. A new relaxation peak of absorption at 10 K has been found in strained samples.

  8. A novel auto-thermal reforming membrane reactor for high purity H2

    Tony Boyd; Grace, J.R.; Lim, C.J.; Adris, A.M.

    2006-01-01

    A novel hydrogen reactor based on steam reforming of natural gas has been developed and tested. The reactor produces high purity hydrogen using in-situ perm-selective membranes installed in a fluidized catalyst bed, thus shifting the thermodynamic equilibrium of the SMR reaction and eliminating the need for downstream hydrogen purification. The reactor is particularly suited to auto-thermal reforming, where air is added to the reformer to provide the endothermic reaction heat, thus eliminating the need to indirectly heat the reactor. The gas flow pattern within the fluidized bed induces an internal circulation of catalyst particles between the central SMR reaction (permeation) zone and an outer annulus. The circulating hot catalyst particles from the oxidation zone carry the required endothermic heat of reaction for the reforming, while ensuring that the palladium membranes are not exposed to excessive temperatures or to oxygen. Another beneficial characteristic of the reactor is that very little of the nitrogen present in the oxidation air reaches the reaction zone, thus maintaining the hydrogen driving force for the perm-selective membranes. Pilot plant results carried out in a semi-industrial scale reactor will be presented. The reactor was operated up to 650 C and 14 bar. Pure hydrogen (99.999+%) was initially obtained from the reactor and an equilibrium shift was demonstrated. (authors)

  9. Optimization of extraction of high purity all-trans-lycopene from tomato pulp waste.

    Poojary, Mahesha M; Passamonti, Paolo

    2015-12-01

    The aim of this work was to optimize the extraction of pure all-trans-lycopene from the pulp fractions of tomato processing waste. A full factorial design (FFD) consisting of four independent variables including extraction temperature (30-50 °C), time (1-60 min), percentage of acetone in n-hexane (25-75%, v/v) and solvent volume (10-30 ml) was used to investigate the effects of process variables on the extraction. The absolute amount of lycopene present in the pulp waste was found to be 0.038 mg/g. The optimal conditions for extraction were as follows: extraction temperature 20 °C, time 40 min, a solvent composition of 25% acetone in n-hexane (v/v) and solvent volume 40 ml. Under these conditions, the maximal recovery of lycopene was 94.7%. The HPLC-DAD analysis demonstrated that, lycopene was obtained in the all-trans-configuration at a very high purity grade of 98.3% while the amount of cis-isomers and other carotenoids were limited. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Photoluminescence measurement of polycrystalline CdTe made of high purity source material

    Hempel, Hannes; Kraft, Christian; Heisler, Christoph; Geburt, Sebastian; Ronning, Carsten; Wesch, Werner [Institute of Solid State Physics, Friedrich Schiller Universitaet Jena, Helmholtzweg 3, 07743 Jena (Germany)

    2012-07-01

    CdTe is a common material for thin film solar cells. However, the mainly used CdTe source material is known to contain a high number of intrinsic defects and impurities. In this work we investigate the defect structure of high purity CdTe by means of Photoluminescence, which is a common method to detect the energy levels of defects in the band gap of semiconductors. We used a 633 nm HeNe-Laser at sample temperatures of 8 K. The examined samples were processed in a new vacuum system based on the PVD method. They yield significantly different spectra on as-grown samples compared to those measured on samples which are grown by the standard process, since the double peak at 1.55 eV was hardly detectable and the A-center correlated transition vanished. Instead a peak at 1.50 eV with pronounced phonon coupling was observed. The 1.50 eV peak is known from other measurements but has not been characterized so far. The intention of this work is to characterize this new feature and the influence of post deposition treatments of the CdTe layers on the PL spectra.

  11. Preparation of high purity metallic protactinium. Crystal structure and dissolution enthalpy of the metal

    Bohet, J.

    1977-01-01

    Some 300 mg of Pa have been produced in a high purity metallic state. Protactinium monocarbide has been obtained by the carboreduction of Pa 2 O 5 . Protactinium iodide, produced by the direct reaction of iodine on the carbide, has been sublimated at 420 0 C and thermally dissociated at 1200 0 C on a W wire. In these conditions Pa metal has been deposited with a yield greater than 85% and presents a bct structure stable at room temperature (a=3.921+-0.001A and c=3.235+-0.001A). The fcc phase (Fm3m type) (a=5.018+-0.001A) has been obtained by quenching metallic samples (bct) heated in argon at 1500 0 C. The chemical analysis and the transformation of the fcc into bct phase by controlled heat treatments show the presence of this high temperature phase in the metal. Protactinium mononitride (5.58% N) produced by direct reaction of N on Pa at 1100 0 C presents the same fcc crystal structure but the lattice parameter is higher (a=5.047+-0.001A). The dissolution heat of metallic Pa (bct) has been determined in the aqueous solution HCl 12M - HF 0.05M at 298.15+-0.05 K. The standard formation enthalpies of the ionic species Pa(IV) and Pa(V) are respectively equal to -672+-15 kJ.mol -1 and -821+-15 kJ.mol -1

  12. The characteristics of void distribution in spalled high purity copper cylinder under sweeping detonation

    Yang, Yang; Jiang, Zhi; Chen, Jixinog; Guo, Zhaoliang; Tang, Tiegang; Hu, Haibo

    2018-03-01

    The effects of different peak compression stresses (2-5 GPa) on the spallation behaviour of high purity copper cylinder during sweeping detonation were examined by Electron Backscatter Diffraction Microscopy, Doppler Pins System and Optical Microscopy techniques. The velocity history of inner surface and the characteristics of void distributions in spalled copper cylinder were investigated. The results indicated that the spall strength of copper in these experiments was less than that revealed in previous reports concerning plate impact loading. The geometry of cylindrical copper and the obliquity of incident shock during sweeping detonation may be the main reasons. Different loading stresses seemed to be responsible for the characteristics of the resultant damage fields, and the maximum damage degree increased with increasing shock stress. Spall planes in different cross-sections of sample loaded with the same shock stress of 3.29 GPa were found, and the distance from the initiation end has little effect on the maximum damage degree (the maximum damage range from 12 to 14%), which means that the spallation behaviour was stable along the direction parallel to the detonation propagation direction under the same shock stress.

  13. MIS High-Purity Plutonium Oxide Metal Oxidation Product TS707001 (SSR123): Final Report

    Veirs, Douglas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stroud, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Berg, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Narlesky, Joshua Edward [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Worl, Laura Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Max A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carillo, Alex [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-09

    A high-purity plutonium dioxide material from the Material Identification and Surveillance (MIS) Program inventory has been studied with regard to gas generation and corrosion in a storage environment. Sample TS707001 represents process plutonium oxides from several metal oxidation operations as well as impure and scrap plutonium from Hanford that are currently stored in 3013 containers. After calcination to 950°C, the material contained 86.98% plutonium with no major impurities. This study followed over time, the gas pressure of a sample with nominally 0.5 wt% water in a sealed container with an internal volume scaled to 1/500th of the volume of a 3013 container. Gas compositions were measured periodically over a six year period. The maximum observed gas pressure was 138 kPa. The increase over the initial pressure of 80 kPa was primarily due to generation of nitrogen and carbon dioxide gas in the first six months. Hydrogen and oxygen were minor components of the headspace gas. At the completion of the study, the internal components of the sealed container showed signs of corrosion, including pitting.

  14. X-ray quantitative analysis on spallation response in high purity copper under sweeping detonation

    Yang, Yang, E-mail: yangyanggroup@163.com [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China); National Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Key Laboratory of Nonferrous Metals Material Science and Engineering of Ministry of Education, Central South University, Changsha 410083 (China); Chen, Jixiong; Peng, Zhiqiang [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Guo, Zhaoliang; Tang, Tiegang; Hu, Haibo [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China); Hu, Yanan [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2016-06-14

    The 3-D quantitative investigation of spall behavior in high purity copper plants with different heat treatment histories was characterized using X-ray computer tomography (XRCT). The effect of shock stress and grain size on the spatial distribution and morphology of incipient spall samples were discussed. The results revealed that, in samples with similar microstructure, the ranges of void distribution decrease with the increasing of shock stress. The characteristic parameters (such as mean elongation, mean flatness and mean sphericity of voids) determined using XRCT herein as a function of shock stress and grain size. The quantitative analyses of spallation datasets render functional relationships between the microscopic parameters (like volume, frequency) of spallation voids and the microstructure. The XRCT observations show that voids are prone to coalescence in thermo-mechanical treatments (TMT) sample, while the final maximum and mean volume of void were smaller than that of annealed sample. This is due to the smaller grain size of TMT sample, which means more nucleation sites of voids, this made the voids get closer and easier to coalescence, and flat voids formed ultimately.

  15. Interaction between a high purity magnesium surface and PCL and PLA coatings during dynamic degradation

    Chen Ying; Song Yang; Zhang Shaoxiang; Li Jianan; Zhao Changli; Zhang Xiaonong, E-mail: xnzhang@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2011-04-15

    In this study, polycaprolactone (PCL) and polylactic acid (PLA) coatings were prepared on the surface of high purity magnesium (HPMs), respectively, and electrochemical and dynamic degradation tests were used to investigate the degradation behaviors of these polymer-coated HPMs. The experimental results indicated that two uniform and smooth polymer films with thicknesses between 15 and 20 {mu}m were successfully prepared on the HPMs. Electrochemical tests showed that both PCL-coated and PLA-coated HPMs had higher free corrosion potentials (E{sub corr}) and smaller corrosion currents (I{sub corr}) in the modified simulated body fluid (m-SBF) at 37 {sup 0}C, compared to those of the uncoated HPMs. Dynamic degradation tests simulating the flow conditions in coronary arteries were carried out on a specific test platform. The weight of the specimens and the pH over the tests were recorded to characterize the corrosion performance of those samples. The surfaces of the specimens after the dynamic degradation tests were also examined. The data implied that there was a special interaction between HPM and its polymer coatings during the dynamic degradation tests, which undermined the corrosion resistance of the coated HPMs. A model was proposed to illustrate the interaction between the polymer coatings and HPM. This study also suggested that this reciprocity may also exist on the implanted magnesium stents coated with biodegradable polymers, which is a potential obstacle for the further development of drug-eluting magnesium stents.

  16. Neutron activation analysis of high purity silver using high resolution gamma-spectrometry

    Gilbert, E.N.; Veriovkin, G.V.; Botchkaryov, B.N.; Godovikov, A.A.; Zhavoronkov, V.Ya.; Mikhailov, V.A.

    1975-01-01

    A method of neutron activation determination of microimpurities in high purity silver has been developed. For matrix activity separation the extraction of silver by dibuthylsulfide /DBS/ was employed. The purification coefficient was 10 8 after triple extraction. To study the behaviour of microimpurities in the extraction procedure and to determine their chemical yields some tracer experiments were undertaken with radionuclides of Na, Se, Fe, Co, Cu, As, Sc, Te, Zr, Hf, Mo, W, Cd, In, Sb, La, Ce, Eu, Ta, Re, Ir, Ru. All the elements studied were found to remain in the aqueous phase up to 96-99% after triple extraction with DBS. To estimate the accuracy of the method and to study the mutual influence of the elements in the sample in various relative amounts on the accuracy of the analysis, a number of experiments of ''added-found'' type was performed and the results were treated statistically. In these experiments model mixtures of 30 nuclides were analysed after triple DBS extraction. The t-criterion values for the confidence interval at P=0.95 show the absence of systematic errors. Variation coefficient values do not exceed 15%. Using Ge/Li/ detector it was possible to determine 30 elements simultaneously in silver samples. (T.G.)

  17. MIS High-Purity Plutonium Oxide Hydride Product 5501579 (SSR124): Final Report

    Veirs, Douglas Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stroud, Mary Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Berg, John M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Narlesky, Joshua Edward [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Worl, Laura Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinex, Max A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carillo, Alex [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-02-08

    A high-purity plutonium dioxide material from the Material Identification and Surveillance (MIS) Program inventory has been studied with regard to gas generation and corrosion in a storage environment. Sample 5501579 represents process plutonium oxides from hydride oxide from Rocky Flats that are currently stored in 3013 containers. After calcination to 950°C, the material contained 87.42% plutonium with no major impurities. This study followed over time, the gas pressure of a sample with nominally 0.5 wt% water in a sealed container with an internal volume scaled to 1/500th of the volume of a 3013 container. Gas compositions were measured periodically over a six year period. The maximum observed gas pressure was 124 kPa. The increase over the initial pressure of 70 kPa was primarily due to generation of nitrogen and carbon dioxide gas. Hydrogen and oxygen were minor components of the headspace gas. At the completion of the study, the internal components of the sealed container showed signs of corrosion.

  18. Contribution to the study of the conductivity of high purity water

    Nens, Ch.

    1964-01-01

    In this work a study is made more particularly of two points: the production of high purity water and the estimation of this purity by means of conductivity measurements. As far as water purification is concerned it is observed that the de-ionisation produced by ion exchange resins in mixed beds leads to a water having a lower conductivity than that obtained by distillation. This low conductivity however, measured at the column exit before the water comes into contact with air is not stable. In fact the carbon dioxide in the water gives rise to an equilibrium with production of the ions HCO 3 - , CO 3 -- . These ions are retained during the passage of the water through the resins. They reappear again at the column exit as a result of the displacement of the hydration equilibrium of CO 2 ; because of this the conductivity of the water increases with time. The water obtained by successive distillations does not behave in the same way because no carbon dioxide is present. Distillation is however a costly purification process on an industrial scale, especially if large quantities of water have to be treated. The measurement of these low conductivities is very delicate. The method employed makes use of a direct current and gives reproducible results if care is taken to exclude interfering electric fields by screening the apparatus. (author) [fr

  19. Influence of Ta Content in High Purity Niobium on Cavity Performance Preliminary Results*

    Kneisel, P

    2004-01-01

    In a previous paper* a program designed to study the influence of the residual tantalum content on the superconducting properties of pure niobium metal for RF cavities was outlined. The main rationale for this program was based on a potential cost reduction for high purity niobium, if a less strict limit on the chemical specification for Ta content, which is not significantly affecting the RRR–value, could be tolerated for high performance cavities. Four ingots with different Ta contents have been melted and transformed into sheets. In each manufacturing step the quality of the material has been monitored by employing chemical analysis, neutron activation analysis, thermal conductivity measurements and evaluation of the mechanical properties. The niobium sheets have been scanned for defects by an eddy current device. From three of the four ingots—Ta contents 100, 600 and 1,200 wppm—two single cell cavities each of the CEBAF variety have been fabricated and a series of tests on each ...

  20. Simultaneously Recovering High-Purity Chromium and Removing Organic Pollutants from Tannery Effluent

    Jie Zong

    2016-01-01

    Full Text Available Chromium pollution is a serious issue because of carcinogenic toxicities of the pollutants and low recovery rate of chromium because of the presence of organic, such as protein and fat. In this work, high recovery rate and high purity of the chromium ion were successfully prepared by the way of acid enzyme, flocculant, and Fenton oxidation. The experiments were characterized by TG, TOC, UV-VIS, and SEM. In the work, the tannery waste chrome liquor was used as experimental material. The results showed that the percentage of reduction of TOC in the tannery waste chrome liquor by method of Fenton oxidation, acid enzyme, and the flocculant was 71.15%, 65.26%, and 22.05%, respectively. Therefore, the organism content of chrome tanning waste liquid was greatly reduced through the pretreatment. And the application experiment showed that the properties and grain surface and fibers of the tanned leather with commercial chromium powder and chrome tanning agent prepared from the chromium waste liquid treated with Fenton are nearly the same.

  1. [Evaluation of the efficacy of sentinel node detection in breast cancer: chronological course and influence of the incorporation of an intra-operative portable gamma camera].

    Goñi Gironés, E; Vicente García, F; Serra Arbeloa, P; Estébanez Estébanez, C; Calvo Benito, A; Rodrigo Rincón, I; Camarero Salazar, A; Martínez Lozano, M E

    2013-01-01

    To define the sentinel node identification rate in breast cancer, the chronological evolution of this parameter and the influence of the introduction of a portable gamma camera. A retrospective study was conducted using a prospective database of 754 patients who had undergone a sentinel lymph node biopsy between January 2003 and December 2011. The technique was mixed in the starting period and subsequently was performed with radiotracer intra-peritumorally administered the day before of the surgery. Until October 2009, excision of the sentinel node was guided by a probe. After that date, a portable gamma camera was introduced for intrasurgical detection. The SN was biopsied in 725 out of the 754 patients studied. The resulting technique global effectiveness was 96.2%. In accordance with the year of the surgical intervention, the identification percentage was 93.5% in 2003, 88.7% in 2004, 94.3% in 2005, 95.7% in 2006, 93.3% in 2007, 98.8% in 2008, 97.1% in 2009 and 99.1% in 2010 and 2011. There was a significant difference in the proportion of identification before and after the incorporation of the portable gamma camera of 4.6% (95% CI of the difference 2-7.2%, P = 0.0037). The percentage of global identification exceeds the recommended level following the current guidelines. Chronologically, the improvement for this parameter during the study period has been observed. These data suggest that the incorporation of a portable gamma camera had an important role. Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.

  2. Measuring of main parameters of blood circulation at small laboratory animals in chronic experiment by means of computerized gamma-camera

    Rutskij, A.V.; Kovalenko, Yu.D.; Rudenko, F.V.; Ioda, G.I.; Kaminskij, M.P.

    1996-01-01

    Technique for studding of a state systemic and regional hemodynamics at small laboratory animals (rats) by using short-lived isotopes (technetium 99 m) and computerized gamma-camera are described. One gives possibility to make the repeated measuring in condition long-tome experiment. The proposed technique of radiocardiocirculography gives possibility simultaneously to measure linear parameters of both arterial and vein blood circulation too. 3 refs., 1 tab., 2 figs

  3. Local deposition of high-purity Pt nanostructures by combining electron beam induced deposition and atomic layer deposition

    Mackus, A.J.M.; Mulders, J.J.L.; Sanden, van de M.C.M.; Kessels, W.M.M.

    2010-01-01

    An approach for direct-write fabrication of high-purity platinum nanostructures has been developed by combining nanoscale lateral patterning by electron beam induced deposition (EBID) with area-selective deposition of high quality material by atomic layer deposition (ALD). Because virtually pure,

  4. Design and development of fluidized bed reactor system for production of trichlorosilane as a precursor for high purity silicon

    Kumar, Rajesh; Mohan, Sadhana; Bhanja, K.; Nayak, S.; Bhattacharya, S.K.

    2009-01-01

    Trichlorosilane is widely used as precursor material for production of high purity silicon. It is mainly produced by reaction of metallurgical grade silicon with anhydrous HCl gas in a fluidized bed reactor. To develop this process on commercial scale a pilot size fluidized bed reactor system was designed and developed and successfully operated. This paper discusses the critical issues related to these activities. (author)

  5. Development of new gamma camera localization method for sentinel nodes by image fusion and navigation in lymphoscintigraphy

    Fidler, V.; Milanez, T.; Prepadnik, M.; Skalic, S.; Skalic, K.; Vidrgar-Kralj, B.; Fidler, S.; Medved, M.

    2004-01-01

    Full text: The objective of this study was the development of the localization technique for skin marking the lesions with low accumulating Tc-99m labeled radiopharmaceuticals. Fusion of high count static planar scan (base image) with real time acquired scan (fluent image) and with added moving point source (Tc-99m or Co-57) in the same patient position was performed for best overlapping the target lesions and point source spot. Special acquisition software in Windows (Oncology MedicView) was developed. Both images were pre-processed by online visual inspection and then fluently fused in the way that only point source spot is overlapped to the base image. Image normalization was done by linear, log or combined log/linear conversions followed by on-line contrasting of fused image by high sensitive color scaling and spatial contrast filtering. The localization was performed in several patient positions with fixed bed and patient. Navigation tools using audio and visual signals were continuously created from the 'lesion-point source spot' distance information. Localization accuracy for SLN(s) using this technique was considerably high. SLN detection improved from 76 % (95 patients, 72 detected SLNs, 23 undetectable SLNs) to 95 % (45 pts, 42 detected SLNs, 3 undetectable SLNs). Localization procedure was shortened for at least 3 times. The new technique substantially lowered the localization time and increased the lesion detection by on-line interactive optimization of fused images. It can be used for all radioisotope localizations in oncology diagnostics using simple analog or semi digital gamma cameras connected to low-cost IAEA acquisition module and specially developed acquisition/processing software. (author)

  6. The clinical impact of a combined gamma camera/CT imaging system on somatostatin receptor imaging of neuroendocrine tumours

    Hillel, P.G.; Beek, E.J.R. van; Taylor, C.; Lorenz, E.; Bax, N.D.S.; Prakash, V.; Tindale, W.B.

    2006-01-01

    AIM: With a combined gamma camera/CT imaging system, CT images are obtained which are inherently registered to the emission images and can be used for the attenuation correction of SPECT and for mapping the functional information from these nuclear medicine tomograms onto anatomy. The aim of this study was to evaluate the clinical impact of SPECT/CT using such a system for somatostatin receptor imaging (SRI) of neuroendocrine tumours. MATERIALS AND METHODS: SPECT/CT imaging with 111 In-Pentetreotide was performed on 29 consecutive patients, the majority of whom had carcinoid disease. All SPECT images were first reported in isolation and then re-reported with the addition of the CT images for functional anatomical mapping (FAM). RESULTS: Fifteen of the 29 SPECT images were reported as abnormal, and in 11 of these abnormal images (73%) FAM was found to either establish a previously unknown location (7/11) or change the location (4/11) of at least one lesion. The revised location could be independently confirmed in 64% of these cases. Confirmation of location was not possible in the other patients due to either a lack of other relevant investigations, or the fact that lesions seen in the SPECT images were not apparent in the other investigations. FAM affected patient management in 64% of the cases where the additional anatomical information caused a change in the reported location of lesions. CONCLUSION: These results imply that FAM can improve the reporting accuracy for SPECT SRI with significant impact on patient management

  7. A method to quantitate cerebral blood flow using a rotating gamma camera and iodine-123 iodoamphetamine with one blood sampling

    Iida, Hidehiro; Itoh, Hiroshi; Bloomfield, P.M.; Munaka, Masahiro; Higano, Shuichi; Murakami, Matsutaro; Inugami, Atsushi; Eberl, S.; Aizawa, Yasuo; Kanno, Iwao; Uemura, Kazuo

    1994-01-01

    A method has been developed to quantitate regional cerebral blood blow (rCBF) using iodine-123-labelled N-isopropyl-p-iodoamphetamine (IMP). This technique requires only two single-photon emission tomography (SPET) scans and one blood sample. Based on a two-compartment model, radioactivity concentrations in the brain for each scan time are calculated. A standard input function has been generated by combining the input functions from 12 independent studies prior to this work to avoid frequent arterial blood sampling, and one blood sample is taken at 10 min following IMP administration for calibration of the standard arterial input function. This calibration time was determined such that the integration of the first 40 min of the calibrated, combined input function agreed best with those from 12 individual input functions (the difference was 5.3% on average). This method was applied to eight subjects (two normals and six patients with cerebral infarction), and yielded rCBF values which agreed well with those obtained by a positron emission tomography H 2 15 O autoradiography method. This method was also found to provide rCBF values that were consistent with those obtained by the non-linear least squares fitting technique and those obtained by conventional microsphere model analysis. The optimum SPET scan times were found to be 40 and 180 min for the early and delayed scans, respectively. These scan times allow the use of a conventional rotating gamma camera for clinical purposes. V d values ranged between 10 and 40 ml/g depending on the pathological condition, thereby suggesting the importance of measuring V d for each ROI. In conclusion, optimization of the blood sampling time and the scanning time enabled quantitative measurement of rCBF with two SPET scans and one blood sample. (orig.)

  8. Physical assessment of the GE/CGR Neurocam and comparison with a single rotating gamma-camera

    Kouris, K.; Jarritt, P.H.; Costa, D.C.; Ell, P.J.

    1992-01-01

    The GE/CGR Neurocam is a triple-headed single photon emission tomography (SPET) system dedicated to multi-slice brain tomography. We have assessed its physical performance in terms of sensitivity and resolution, and its clinical efficacy in comparison with a modern, single, rotating gamma-camera (GE 400XCT). Using a water-filled cylinder containing TC-99m, the tomographic volume sensitivity of the Neurocam was 30.0 and 50.7 kcps/MBq.ml.cm for the high-resolution and general-purpose collimators, respectively; the corresponding values for the single rotating camera were 7.6 and 12.8 kcps/MBq.ml.cm. Tomographic resolution was measured in air and in water. In air, the Neurocam resolution at the centre of the field-of-view is 9.0 and 10.7 mm full width at half-maximum (FWHM) with the collimators, respectively, and is isotropic in the three orthogonal planes; the resolution of the GE 400XCT with its 13-cm radius of rotation is 10.3 and 11.7 mm, respectively. For the Neurocam with the HR collimator, the transaxial FWHM values in water were 9.7 mm at the centre and 9.5 mm radial (6.6 mm tangential) at 8 cm from the centre. The physical characteristics of the Neurocam enable the routine acquisition of brain perfusion data with Tc-99m hexamethyl-propylene amine oxime in about 14 min, yielding better image quality than with a single rotating camera in 40 min. (orig./HP)

  9. Cerebral emission computer tomography with a rotating gamma camera: clinic results with J-123 Isopropylamphetamin and J-123-Fenetyllin

    Biersack, H.J.; Hartmann, A.; Froescher, W.; Reske, S.-N.; Reichmann, K.; Knopp, R.; Winkler, C.

    1984-01-01

    Many amines can pass the blood brain barrier and accumulate in relatively large amounts in the brain tissue. For about 2 years 123-J amphetamines have, therefore, been used for brain imaging by several teams. Our experience sofar is based on 28 patients. Of these, 14 were epileptics, 10 had cerebrovascular diseases, 2 suffered from migraine and another 2 had brain tumors. In 3 patients with vascular lesions studies were repeated twice or three times. Amphetamine uptake in the brain was measured with a rotating gamma camera system (Gammatome T9000/CGR). At an examination time of 20 minutes 64 frames were acquired during one full rotation. The pulse rate was about 3000 second after injecting 6.5 mCi of 123-J amphetamine. Of the epileptics, 8 showed defects both on CT and SPECT, in 3 cases both studies were normal. While 1 patient with CT positivity had a normal SPECT, 2 cases were found to have lesions on SPECT inspite of a normal CT. The size of the lesion seen on amphetamine SPECT was lager than on CT in 3 of 9 patients. In the 10 patients with cerebrovascular lesions the 2 procedures showed concordant normal patterns in 1 and concordant abnormal patterns in 7 instances. 2 patients with normal CT were found to have a lesion on amphetamine scanning which corresponded to the neurologic findings. Regarding the size of the lesions, SPECT showed a more extensive involvement than CT in 2 cases. This again was in good agreement with the neurologic findings. Inspite of repeat studies cerebellar diaschisis was only seen in a single case with healed cerebral infarction and hemiplegia of some years' standing. Two patients suffered from migraine and compromised blood flow was identified as suggested by the neurologic findings inspite of a normal CT. (Author)

  10. Calibration of gamma camera systems for a multicentre European {sup 123}I-FP-CIT SPECT normal database

    Tossici-Bolt, Livia [Southampton Univ. Hospitals NHS Trust, Dept. of Medical Physics and Bioengineering, Southampton (United Kingdom); Dickson, John C. [UCLH NHS Foundation Trust and Univ. College London, Institute of Nuclear Medicine, London (United Kingdom); Sera, Terez [Univ. of Szeged, Dept. of Nuclear Medicine and Euromedic Szeged, Szeged (Hungary); Nijs, Robin de [Rigshospitalet and Univ. of Copenhagen, Neurobiology Research Unit, Copenhagen (Denmark); Bagnara, Maria Claudia [Az. Ospedaliera Universitaria S. Martino, Medical Physics Unit, Genoa (Italy); Jonsson, Cathrine [Karolinska Univ. Hospital, Dept. of Nuclear Medicine, Medical Physics, Stockholm (Sweden); Scheepers, Egon [Univ. of Amsterdam, Dept. of Nuclear Medicine, Academic Medical Centre, Amsterdam (Netherlands); Zito, Felicia [Fondazione IRCCS Granda, Ospedale Maggiore Policlinico, Dept. of Nuclear Medicine, Milan (Italy); Seese, Anita [Univ. of Leipzig, Dept. of Nuclear Medicine, Leipzig (Germany); Koulibaly, Pierre Malick [Univ. of Nice-Sophia Antipolis, Nuclear Medicine Dept., Centre Antoine Lacassagne, Nice (France); Kapucu, Ozlem L. [Gazi Univ., Faculty of Medicine, Dept. of Nuclear Medicine, Ankara (Turkey); Koole, Michel [Univ. Hospital and K.U. Leuven, Nuclear Medicine, Leuven (Belgium); Raith, Maria [Medical Univ. of Vienna, Dept. of Nuclear Medicine, Vienna (Austria); George, Jean [Univ. Catholique Louvain, Nuclear Medicine Division, Mont-Godinne Medical Center, Mont-Godinne (Belgium); Lonsdale, Markus Nowak [Bispebjerg Univ. Hospital, Dept. of Clinical Physiology and Nuclear Medicine, Copenhagen (Denmark); Muenzing, Wolfgang [Univ. of Munich, Dept. of Nuclear Medicine, Munich (Germany); Tatsch, Klaus [Univ. of Munich, Dept. of Nuclear Medicine, Munich (Germany); Municipal Hospital of Karlsruhe Inc., Dept. of Nuclear Medicine, Karlsruhe (Germany); Varrone, Andrea [Center for Psychiatric Research, Karolinska Inst., Dept. of Clinical Neuroscience, Stockholm (Sweden)

    2011-08-15

    A joint initiative of the European Association of Nuclear Medicine (EANM) Neuroimaging Committee and EANM Research Ltd. aimed to generate a European database of [{sup 123}I]FP-CIT single photon emission computed tomography (SPECT) scans of healthy controls. This study describes the characterization and harmonization of the imaging equipment of the institutions involved. {sup 123}I SPECT images of a striatal phantom filled with striatal to background ratios between 10:1 and 1:1 were acquired on all the gamma cameras with absolute ratios measured from aliquots. The images were reconstructed by a core lab using ordered subset expectation maximization (OSEM) without corrections (NC), with attenuation correction only (AC) and additional scatter and septal penetration correction (ACSC) using the triple energy window method. A quantitative parameter, the simulated specific binding ratio (sSBR), was measured using the ''Southampton'' methodology that accounts for the partial volume effect and compared against the actual values obtained from the aliquots. Camera-specific recovery coefficients were derived from linear regression and the error of the measurements was evaluated using the coefficient of variation (COV). The relationship between measured and actual sSBRs was linear across all systems. Variability was observed between different manufacturers and, to a lesser extent, between cameras of the same type. The NC and AC measurements were found to underestimate systematically the actual sSBRs, while the ACSC measurements resulted in recovery coefficients close to 100% for all cameras (AC range 69-89%, ACSC range 87-116%). The COV improved from 46% (NC) to 32% (AC) and to 14% (ACSC) (p < 0.001). A satisfactory linear response was observed across all cameras. Quantitative measurements depend upon the characteristics of the SPECT systems and their calibration is a necessary prerequisite for data pooling. Together with accounting for partial volume, the

  11. High-Purity Semiconducting Single-Walled Carbon Nanotubes: A Key Enabling Material in Emerging Electronics.

    Lefebvre, Jacques; Ding, Jianfu; Li, Zhao; Finnie, Paul; Lopinski, Gregory; Malenfant, Patrick R L

    2017-10-17

    Semiconducting single-walled carbon nanotubes (sc-SWCNTs) are emerging as a promising material for high-performance, high-density devices as well as low-cost, large-area macroelectronics produced via additive manufacturing methods such as roll-to-roll printing. Proof-of-concept demonstrations have indicated the potential of sc-SWCNTs for digital electronics, radiofrequency circuits, radiation hard memory, improved sensors, and flexible, stretchable, conformable electronics. Advances toward commercial applications bring numerous opportunities in SWCNT materials development and characterization as well as fabrication processes and printing technologies. Commercialization in electronics will require large quantities of sc-SWCNTs, and the challenge for materials science is the development of scalable synthesis, purification, and enrichment methods. While a few synthesis routes have shown promising results in making near-monochiral SWCNTs, gram quantities are available only for small-diameter sc-SWCNTs, which underperform in transistors. Most synthesis routes yield mixtures of SWCNTs, typically 30% metallic and 70% semiconducting, necessitating the extraction of sc-SWCNTs from their metallic counterparts in high purity using scalable postsynthetic methods. Numerous routes to obtain high-purity sc-SWCNTs from raw soot have been developed, including density-gradient ultracentrifugation, chromatography, aqueous two-phase extraction, and selective DNA or polymer wrapping. By these methods (termed sorting or enrichment), >99% sc-SWCNT content can be achieved. Currently, all of these approaches have drawbacks and limitations with respect to electronics applications, such as excessive dilution, expensive consumables, and high ionic impurity content. Excess amount of dispersant is a common challenge that hinders direct inclusion of sc-SWCNTs into electronic devices. At present, conjugated polymer extraction may represent the most practical route to sc-SWCNTs. By the use of

  12. N-Type delta Doping of High-Purity Silicon Imaging Arrays

    Blacksberg, Jordana; Hoenk, Michael; Nikzad, Shouleh

    2005-01-01

    A process for n-type (electron-donor) delta doping has shown promise as a means of modifying back-illuminated image detectors made from n-doped high-purity silicon to enable them to detect high-energy photons (ultraviolet and x-rays) and low-energy charged particles (electrons and ions). This process is applicable to imaging detectors of several types, including charge-coupled devices, hybrid devices, and complementary metal oxide/semiconductor detector arrays. Delta doping is so named because its density-vs.-depth characteristic is reminiscent of the Dirac delta function (impulse function): the dopant is highly concentrated in a very thin layer. Preferably, the dopant is concentrated in one or at most two atomic layers in a crystal plane and, therefore, delta doping is also known as atomic-plane doping. The use of doping to enable detection of high-energy photons and low-energy particles was reported in several prior NASA Tech Briefs articles. As described in more detail in those articles, the main benefit afforded by delta doping of a back-illuminated silicon detector is to eliminate a "dead" layer at the back surface of the silicon wherein high-energy photons and low-energy particles are absorbed without detection. An additional benefit is that the delta-doped layer can serve as a back-side electrical contact. Delta doping of p-type silicon detectors is well established. The development of the present process addresses concerns specific to the delta doping of high-purity silicon detectors, which are typically n-type. The present process involves relatively low temperatures, is fully compatible with other processes used to fabricate the detectors, and does not entail interruption of those processes. Indeed, this process can be the last stage in the fabrication of an imaging detector that has, in all other respects, already been fully processed, including metallized. This process includes molecular-beam epitaxy (MBE) for deposition of three layers, including

  13. High purity Fe3O4 from Local Iron Sand Extraction

    Gunanto, Y. E.; Izaak, M. P.; Jobiliong, E.; Cahyadi, L.; Adi, W. A.

    2018-04-01

    Indonesia has a long coastline and is rich with iron sand. The iron sand is generally rich in various elements such as iron and titanium. One of the products processing of the iron sand mineral is iron (II) (III) oxide (magnetite Fe3O4). The stages of purification process to extracting magnetite phase and discarding the other phases has been performed. Magnetite phase analysis of ironsand extraction retrieved from Indonesia have been investigated. The result of analysis element of iron sand shows that it consists of majority Fe around 65 wt%. However, there are still 17 impurities such as Ti, Al, Ce, Co, Cr, Eu, La, Mg, Mn, Na, Sc, Sm, Th, V, Yb, and Zn. After extraction process, Fe element content increases up to 94%. The iron sand powder after milling for 10 hours and separating using a magnetic separator, the iron sand powders are dissolved in acid chloride solution to form a solution of iron chloride, and this solution is sprinkled with sodium hydroxide to obtain fine powders of Fe3O4. The fine powders which formed were washed with de-mineralization water. The X-ray diffraction pattern shows that the fine powders have a single phase of Fe3O4. The analysis result shows that the sample has the chemical formula: Fe3O4 with a cubic crystal system, space group: Fd-3m and lattice parameters: a = b = c = 8.3681 (1) Å, α = β = γ = 90°. The microstructure analysis shows that the particle of Fe3O4 homogeneously shaped like spherical. The magnetic properties using vibrating sample magnetometer shows that Fe3O4 obtained have ferromagnetic behavior with soft magnetic characteristics. We concluded that this purification of iron sand had been successfully performed to obtain fine powders of Fe3O4 with high purity.

  14. A green preparation of Mn-based product with high purity from low-grade rhodochrosite

    Lian, F.; Ma, L.; Chenli, Z.; Mao, L.

    2018-01-01

    The low-grade rhodochrosite, the main resources for exploitation and applications in China, contains multiple elements such as iron, silicon, calcium and magnesium. So the conventional preparation of manganese sulphate and manganese oxide with high purity from electrolytic product is characterized by long production-cycle, high-resource input and high-pollution discharge. In our work, a sustainable preparation approach of high pure MnSO4 solution and Mn3O4 was studied by employing low-grade rhodochrosite (13.86%) as raw material. The repeated leaching of rhodochrosite with sulphuric acid was proposed in view of the same ion effect, in order to improve the solubility of Mn2+ and inhibit the dissolution of the impurities Ca2+ and Mg2+. With the aid of theoretical calculation, BaF2 was chosen to remove Ca2+ and Mg2+ completely in the process of purifying. The results showed that the impurities such as Ca2+, Mg2+, Na+ were decreased to less than 20ppm, and the Ni- and Fe- impurities were decreased to less than 1ppm, which meets the standards of high pure reagent for energy and electronic materials. The extraction ratio and the recovery ratio of manganese reached 94.3% and 92.7%, respectively. Moreover, the high pure Mn3O4 was one-step synthesized via the oxidation of MnSO4 solution with the ratios of OH-/Mn2+=2 and Mn2+/H2O2=1.03, and the recovery rate of manganese reaches 99%.

  15. Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

    Abd-Elnaiem, Alaa M., E-mail: alaa.abd-elnaiem@science.au.edu.eg [KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Mebed, A.M. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Department of Physics, Faculty of Science, Al-Jouf University, Sakaka 2014 (Saudi Arabia); El-Said, Waleed Ahmed [Department of Chemistry, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Abdel-Rahim, M.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

    2014-11-03

    Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes.

  16. Melt-drop technique for the production of high-purity metal powder

    Aldinger, F.; Linck, E.; Claussen, N.

    1977-01-01

    The production of high-purity powders of metals and alloys such as beryllium, titanium alloys, or superalloys is a problem. Oxidation of these materials cannot be avoided. Oxidation occurs in inert gases and even in reducing atmospheres when any gas impurities are present. Therefore, the powder production of these materials has to be performed either in high vacuum or at least in a static atmosphere of inert gas purified immediately before coming into contact with the disintegrating material. These requirements are very well met by the melt-drop technique presented in this paper, especially for coarse powders which must not necessarily be cold-workable. This is true, for example, for superalloys where high-temperature applications require large grain sizes; or in titanium alloys because the final microstructure will be achieved by a thermomechanical treatment. In the case of beryllium and beryllium alloys, where grain sizes <5 μm are desired, further milling is necessary. But the melt-drop technique offers a simple and clean method directly from the purifying process of vacuum melting. In melt-drop processes a liquid metal flows through a nozzle at the bottom of a crucible or the melt is just poured through a sieve. The theory of disintegration of a liquid jet into droplets, dates back to the 19th century. More recent investigations attempted to produce uniformly sized droplets by applying a capillary wave of given wave length to the jet. But this has been done only with non-metallic materials. Evidence is presented to prove the theory and show that this concept is applicable to the production of metal powders with controlled particle size

  17. Metallic oxide nano-clusters synthesis by ion implantation in high purity Fe10Cr alloy

    Zheng, Ce

    2015-01-01

    ODS (Oxide Dispersed Strengthened) steels, which are reinforced with metal dispersions of nano-oxides (based on Y, Ti and O elements), are promising materials for future nuclear reactors. The detailed understanding of the mechanisms involved in the precipitation of these nano-oxides would improve manufacturing and mechanical properties of these ODS steels, with a strong economic impact for their industrialization. To experimentally study these mechanisms, an analytical approach by ion implantation is used, to control various parameters of synthesis of these precipitates as the temperature and concentration. This study demonstrated the feasibility of this method and concerned the behaviour of alloys models (based on aluminium oxide) under thermal annealing. High purity Fe-10Cr alloys were implanted with Al and O ions at room temperature. Transmission electron microscopy observations showed that the nano-oxides appear in the Fe-10Cr matrix upon ion implantation at room temperature without subsequent annealing. The mobility of implanted elements is caused by the defects created during ion implantation, allowing the nucleation of these nanoparticles, of a few nm in diameter. These nanoparticles are composed of aluminium and oxygen, and also chromium. The high-resolution experiments show that their crystallographic structure is that of a non-equilibrium compound of aluminium oxide (cubic γ-Al 2 O 3 type). The heat treatment performed after implantation induces the growth of the nano-sized oxides, and a phase change that tends to balance to the equilibrium structure (hexagonal α-Al 2 O 3 type). These results on model alloys are fully applicable to industrial materials: indeed ion implantation reproduces the conditions of milling and heat treatments are at equivalent temperatures to those of thermo-mechanical treatments. A mechanism involving the precipitation of nano-oxide dispersed in ODS alloys is proposed in this manuscript based on the obtained experimental results

  18. Porous and mesh alumina formed by anodization of high purity aluminum films at low anodizing voltage

    Abd-Elnaiem, Alaa M.; Mebed, A.M.; El-Said, Waleed Ahmed; Abdel-Rahim, M.A.

    2014-01-01

    Electrochemical oxidation of high-purity aluminum (Al) films under low anodizing voltages (1–10) V has been conducted to obtain anodic aluminum oxide (AAO) with ultra-small pore size and inter-pore distance. Different structures of AAO have been obtained e.g. nanoporous and mesh structures. Highly regular pore arrays with small pore size and inter-pore distance have been formed in oxalic or sulfuric acids at different temperatures (22–50 °C). It is found that the pore diameter, inter-pore distance and the barrier layer thickness are independent of the anodizing parameters, which is very different from the rules of general AAO fabrication. The brand formation mechanism has been revealed by the scanning electron microscope study. Regular nanopores are formed under 10 V at the beginning of the anodization and then serve as a template layer dominating the formation of ultra-small nanopores. Anodization that is performed at voltages less than 5 V leads to mesh structured alumina. In addition, we have introduced a simple one-pot synthesis method to develop thin walls of oxide containing lithium (Li) ions that could be used for battery application based on anodization of Al films in a supersaturated mixture of lithium phosphate and phosphoric acid as matrix for Li-composite electrolyte. - Highlights: • We develop anodic aluminum oxide (AAO) with small pore size and inter-pore distance. • Applying low anodizing voltages onto aluminum film leads to form mesh structures. • The value of anodizing voltage (1–10 V) has no effect on pore size or inter-pore distance. • Applying anodizing voltage less than 5 V leads to mesh structured AAO. • AAO can be used as a matrix for Li-composite electrolytes

  19. Raman and photoelectron spectroscopic investigation of high-purity niobium materials: Oxides, hydrides, and hydrocarbons

    Singh, Nageshwar; Deo, M. N.; Nand, Mangla; Jha, S. N.; Roy, S. B.

    2016-09-01

    We present investigations of the presence of oxides, hydrides, and hydrocarbons in high-purity (residual resistivity ratio, ˜300) niobium (Nb) materials used in fabrication of superconducting radio frequency (SRF) cavities for particle accelerators. Raman spectroscopy of Nb materials (as-received from the vendor as well as after surface chemical- and thermal processing) revealed numerous peaks, which evidently show the presence of oxides (550 cm-1), hydrides (1277 and 1385 cm-1: ˜80 K temperature), and groups of hydrocarbons (1096, 2330, 2710, 2830, 2868, and 3080 cm-1). The present work provides direct spectroscopic evidence of hydrides in the electropolished Nb materials typically used in SRF cavities. Raman spectroscopy thus can provide vital information about the near-surface chemical species in niobium materials and will help in identifying the cause for the performance degradation of SRF cavities. Furthermore, photoelectron spectroscopy was performed on the Nb samples to complement the Raman spectroscopy study. This study reveals the presence of C and O in the Nb samples. Core level spectra of Nb (doublet 3d5/2 and 3d3/2) show peaks near 206.6 and 209.4 eV, which can be attributed to the Nb5+ oxidation state. The core level spectra of C 1 s of the samples are dominated by graphitic carbon (binding energy, 284.6 eV), while the spectra of O 1 s are asymmetrically peaked near binding energy of ˜529 eV, and that indicates the presence of metal-oxide Nb2O5. The valence-band spectra of the Nb samples are dominated by a broad peak similar to O 2p states, but after sputtering (for 10 min) a peak appears at ˜1 eV, which is a feature of the elemental Nb atom.

  20. Evaluation of Prebiotic Effects of High-Purity Galactooligosaccharides in vitro and in vivo

    Ki Bae Hong

    2016-01-01

    Full Text Available Galactooligosaccharides (GOS are an important class of dietary prebiotics that exert beneficial effects on intestinal microbiota and gut barrier function. In this study, high-purity GOS (HP-GOS were investigated in vitro and in vivo and confirmed as prebiotic ingredients in rat diet. HP-GOS were successfully produced using a two-step process, enzymatic hydrolysis and fermentation by yeast. They were found to serve as a good substrate and carbon source for supporting the growth of probiotic bacteria more effectively than other commercial GOS. Following administration of 1 % (by mass of HP-GOS to rats, the growth of Bifidobacterium bifidum and B. longum in the gut increased most rapidly up to 12 h, and thereafter the increase was slow. Therefore, 1 % HP-GOS was found to be acceptable for the growth of probiotic bacteria. Groups of animals that were orally administered HP-GOS and bifidobacteria during the study, and the group administered HP-GOS during the 2nd (days 13–15 and 4th (days 28–30 period of the study had significantly (p<0.05 higher numbers of bifidobacteria in faeces than groups receiving a single dose of bifidobacteria. HP-GOS affected the expression of genes encoding glucagon-like peptide-1 (GLP-1 and peptide YY (PYY. There was a significant upregulation of GLP-1 and PYY mRNA with HP-GOS and bifidobacteria intake. We propose that the prebiotic properties of HP-GOS are potentially valuable for the production of functional foods for human consumption.