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Sample records for beam quality factor

  1. Generalized beam quality factor of aberrated truncated Gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2011-07-01

    Full Text Available with a quadratic refractive index profile, a change in the beam quality factor can be used to infer the pre- sence of aberrations and thereby study the media of interest. For these reasons, among others, research into the beam qual- ity factor... very much like a normal lens (without the rotational symmetry associated with defocus) since the beam quality factor is calculated in the principal axes. With y-astigmatism, the lenslike behavior does not take place in the principal axes where...

  2. Quality factor of aberrated gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2010-09-01

    Full Text Available 15 20 25 30 35 M 4 © CSIR 2010 www.csir.co.za Conclusion • Laser beam quality depends on - y-Astigmatism - y-Coma - x-Coma - y-Triangular astigmatism - x-Triangular astigmatism - Spherical aberration...

  3. Quality correction factors of composite IMRT beam deliveries: Theoretical considerations

    International Nuclear Information System (INIS)

    Bouchard, Hugo

    2012-01-01

    Purpose: In the scope of intensity modulated radiation therapy (IMRT) dosimetry using ionization chambers, quality correction factors of plan-class-specific reference (PCSR) fields are theoretically investigated. The symmetry of the problem is studied to provide recommendable criteria for composite beam deliveries where correction factors are minimal and also to establish a theoretical limit for PCSR delivery k Q factors. Methods: The concept of virtual symmetric collapsed (VSC) beam, being associated to a given modulated composite delivery, is defined in the scope of this investigation. Under symmetrical measurement conditions, any composite delivery has the property of having a k Q factor identical to its associated VSC beam. Using this concept of VSC, a fundamental property of IMRT k Q factors is demonstrated in the form of a theorem. The sensitivity to the conditions required by the theorem is thoroughly examined. Results: The theorem states that if a composite modulated beam delivery produces a uniform dose distribution in a volume V cyl which is symmetric with the cylindrical delivery and all beams fulfills two conditions in V cyl : (1) the dose modulation function is unchanged along the beam axis, and (2) the dose gradient in the beam direction is constant for a given lateral position; then its associated VSC beam produces no lateral dose gradient in V cyl , no matter what beam modulation or gantry angles are being used. The examination of the conditions required by the theorem lead to the following results. The effect of the depth-dose gradient not being perfectly constant with depth on the VSC beam lateral dose gradient is found negligible. The effect of the dose modulation function being degraded with depth on the VSC beam lateral dose gradient is found to be only related to scatter and beam hardening, as the theorem holds also for diverging beams. Conclusions: The use of the symmetry of the problem in the present paper leads to a valuable theorem showing

  4. Calculation of beam quality correction factor using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Kawachi, T.; Saitoh, H.; Myojoyama, A.; Katayose, T.; Kojima, T.; Fukuda, K.; Inoue, M.

    2005-01-01

    In recent years, a number of the CyberKnife systems (Accuray C., U.S.) have been increasing significantly. However, the CyberKnife has unique treatment head structure and beam collimating system. Therefore, the global standard protocols can not be adopted for absolute absorbed dose dosimetry in CyberKnife beam. In this work, the energy spectrum of photon and electron from CyberKnife treatment head at 80 cm SSD and several depths in water are simulated with conscientious geometry using by the EGS Monte Carlo method. Furthermore, for calculation of the beam quality correction factor k Q , the mean restricted mass stopping power and the mass energy absorption coefficient of air, water and several chamber wall and waterproofing sleeve materials are calculated. As a result, the factors k Q CyberKnife beam for several ionization chambers are determined. And the relationship between the beam quality index PDD(10) x in CyberKnife beam and k Q is described in this report. (author)

  5. Electron beam water calorimetry measurements to obtain beam quality conversion factors.

    Science.gov (United States)

    Muir, Bryan R; Cojocaru, Claudiu D; McEwen, Malcolm R; Ross, Carl K

    2017-10-01

    To provide results of water calorimetry and ion chamber measurements in high-energy electron beams carried out at the National Research Council Canada (NRC). There are three main aspects to this work: (a) investigation of the behavior of ionization chambers in electron beams of different energies with focus on long-term stability, (b) water calorimetry measurements to determine absorbed dose to water in high-energy beams for direct calibration of ion chambers, and (c) using measurements of chamber response relative to reference ion chambers, determination of beam quality conversion factors, k Q , for several ion chamber types. Measurements are made in electron beams with energies between 8 MeV and 22 MeV from the NRC Elekta Precise clinical linear accelerator. Ion chamber measurements are made as a function of depth for cylindrical and plane-parallel ion chambers over a period of five years to investigate the stability of ion chamber response and for indirect calibration. Water calorimetry measurements are made in 18 MeV and 22 MeV beams. An insulated enclosure with fine temperature control is used to maintain a constant temperature (drifts less than 0.1 mK/min) of the calorimeter phantom at 4°C to minimize effects from convection. Two vessels of different designs are used with calibrated thermistor probes to measure radiation induced temperature rise. The vessels are filled with high-purity water and saturated with H 2 or N 2 gas to minimize the effect of radiochemical reactions on the measured temperature rise. A set of secondary standard ion chambers are calibrated directly against the calorimeter. Finally, several other ion chambers are calibrated in the NRC 60 Co reference field and then cross-calibrated against the secondary standard chambers in electron beams to realize k Q factors. The long-term stability of the cylindrical ion chambers in electron beams is better (always <0.15%) than plane-parallel chambers (0.2% to 0.4%). Calorimetry measurements

  6. Absorbed-dose beam quality conversion factors for cylindrical chambers in high energy photon beams.

    Science.gov (United States)

    Seuntjens, J P; Ross, C K; Shortt, K R; Rogers, D W

    2000-12-01

    Recent working groups of the AAPM [Almond et al., Med. Phys. 26, 1847 (1999)] and the IAEA (Andreo et al., Draft V.7 of "An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water," IAEA, 2000) have described guidelines to base reference dosimetry of high energy photon beams on absorbed dose to water standards. In these protocols use is made of the absorbed-dose beam quality conversion factor, kQ which scales an absorbed-dose calibration factor at the reference quality 60Co to a quality Q, and which is calculated based on state-of-the-art ion chamber theory and data. In this paper we present the measurement and analysis of beam quality conversion factors kQ for cylindrical chambers in high-energy photon beams. At least three chambers of six different types were calibrated against the Canadian primary standard for absorbed dose based on a sealed water calorimeter at 60Co [TPR10(20)=0.572, %dd(10)x=58.4], 10 MV [TPR10(20)=0.682, %dd(10)x=69.6), 20 MV (TPR10(20)=0.758, %dd(10)x= 80.5] and 30 MV [TPR10(20) = 0.794, %dd(10)x= 88.4]. The uncertainty on the calorimetric determination of kQ for a single chamber is typically 0.36% and the overall 1sigma uncertainty on a set of chambers of the same type is typically 0.45%. The maximum deviation between a measured kQ and the TG-51 protocol value is 0.8%. The overall rms deviation between measurement and the TG-51 values, based on 20 chambers at the three energies, is 0.41%. When the effect of a 1 mm PMMA waterproofing sleeve is taken into account in the calculations, the maximum deviation is 1.1% and the overall rms deviation between measurement and calculation 0.48%. When the beam is specified using TPR10(20), and measurements are compared with kQ values calculated using the version of TG-21 with corrected formalism and data, differences are up to 1.6% when no sleeve corrections are taken into account. For the NE2571 and the NE2611A chamber types, for which the most literature data are

  7. The determination of beam quality correction factors: Monte Carlo simulations and measurements.

    Science.gov (United States)

    González-Castaño, D M; Hartmann, G H; Sánchez-Doblado, F; Gómez, F; Kapsch, R-P; Pena, J; Capote, R

    2009-08-07

    Modern dosimetry protocols are based on the use of ionization chambers provided with a calibration factor in terms of absorbed dose to water. The basic formula to determine the absorbed dose at a user's beam contains the well-known beam quality correction factor that is required whenever the quality of radiation used at calibration differs from that of the user's radiation. The dosimetry protocols describe the whole ionization chamber calibration procedure and include tabulated beam quality correction factors which refer to 60Co gamma radiation used as calibration quality. They have been calculated for a series of ionization chambers and radiation qualities based on formulae, which are also described in the protocols. In the case of high-energy photon beams, the relative standard uncertainty of the beam quality correction factor is estimated to amount to 1%. In the present work, two alternative methods to determine beam quality correction factors are prescribed-Monte Carlo simulation using the EGSnrc system and an experimental method based on a comparison with a reference chamber. Both Monte Carlo calculations and ratio measurements were carried out for nine chambers at several radiation beams. Four chamber types are not included in the current dosimetry protocols. Beam quality corrections for the reference chamber at two beam qualities were also measured using a calorimeter at a PTB Primary Standards Dosimetry Laboratory. Good agreement between the Monte Carlo calculated (1% uncertainty) and measured (0.5% uncertainty) beam quality correction factors was obtained. Based on these results we propose that beam quality correction factors can be generated both by measurements and by the Monte Carlo simulations with an uncertainty at least comparable to that given in current dosimetry protocols.

  8. Experimental determination of beam quality conversion factors kQ in clinical photon beams using ferrous sulphate (Fricke) dosimetry

    International Nuclear Information System (INIS)

    Palm, A.; Mattsson, Olof

    2002-01-01

    The implementation of protocols based on absorbed dose to water standards requires beam quality conversion factors, k Q . Calculated values of k Q are available for ionization chambers used for reference dosimetry. Ideally, k Q should be experimentally determined at the same beam qualities as that of the user. In this work we measure k Q factors in clinical photon beams and compare them with calculated and measured values. Beam quality conversion factors are determined for clinical photon beams of nominal energies 4 MV, 6 MV, 15 MV, and 25 MV, for commonly used cylindrical ionization chambers. Twelve chambers of eight different types are used. For three of them, no experimental data have previously been available. The experimental procedure is based on measurements with ionization chambers and Fricke dosimetry in the reference beam ( 60 Co γ radiation) and in clinical linear accelerator beams. The k Q values determined in this work generally agree within 0.5% with previously reported experimental values both when %dd(10) x and TPR 20,10 are used for beam quality specification. The agreement with calculated data is generally within 0.5%, except for the 15 MV beam. For this beam the measured values are usually between 0.5% and 1% lower than the data taken from the TG-51 protocol or the TRS-398 code of practice. For three NE2571 chambers and three NE2581 chambers, the maximum observed deviation of individual k Q values is 0.2% and 0.4%, respectively

  9. Direct measurement of electron beam quality conversion factors using water calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Renaud, James, E-mail: james.renaud@mail.mcgill.ca; Seuntjens, Jan [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4 (Canada); Sarfehnia, Arman [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4, Canada and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Marchant, Kristin [Allan Blair Cancer Centre, Saskatchewan Cancer Agency, Regina, Saskatchewan S4T 7T1, Canada and Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A1 (Canada); McEwen, Malcolm; Ross, Carl [Ionizing Radiation Standards, National Research Council of Canada, Ottawa, Ontario K1A 0R6 (Canada)

    2015-11-15

    Purpose: In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. Methods: A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. Results: The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9–20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%–0.40%) and its influence on the perturbation correction (Type B, 0.10%–0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, k{sub ecal}, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM’s TG-51 protocol

  10. Direct measurement of electron beam quality conversion factors using water calorimetry.

    Science.gov (United States)

    Renaud, James; Sarfehnia, Arman; Marchant, Kristin; McEwen, Malcolm; Ross, Carl; Seuntjens, Jan

    2015-11-01

    In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9-20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%-0.40%) and its influence on the perturbation correction (Type B, 0.10%-0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, kecal, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM's TG-51 protocol. General agreement between the relative

  11. Absorbed dose beam quality factors for cylindrical ion chambers: Experimental determination at 6 and 15 MV photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Caporali, C; Guerra, A S; Laitano, R F; Pimpinella, M [ENEA-Casaccia, Inst. Nazionale di Meterologia delle Radiazioni Ionizzanti, Rome (Italy). Dipt. Ambiente

    1996-08-01

    Ion chambers calibrated in terms of absorbed dose to water need an additional factor conventionally designed by k{sub Q} in order to determine the absorbed dose. The quantity k{sub Q} depends on beam quality and chamber characteristics. Rogers and Andreo provided calculations of the k{sub Q} factors for most commercially available ionization chambers for clinical dosimetry. Experimental determinations of the k{sub Q} factors for a number of cylindrical ion chambers have been made and are compared with the calculated values so far published. Measurements were made at 6 MV and 15 MV clinical photon beams at a point in water phantom where the ion chambers and a Fricke dosimeter were alternatively irradiated. The uncertainty on the experimental k{sub Q} factors resulted about {+-} 0.6%. The theoretical and experimental k{sub Q} values are in fairly good agreement. (author). 12 refs, 3 tabs.

  12. SU-E-T-464: On the Equivalence of the Quality Correction Factor for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Sorriaux, J; Paganetti, H; Testa, M; Giantsoudi, D; Schuemann, J; Bertrand, D; Orban de Xivry, J.; Lee, J; Palmans, H; Vynckier, S; Sterpin, E

    2014-01-01

    Purpose: In current practice, most proton therapy centers apply IAEA TRS-398 reference dosimetry protocol. Quality correction factors (kQ) take into account in the dose determination process the differences in beam qualities used for calibration unit and for treatment unit. These quality correction factors are valid for specific reference conditions. TRS-398 reference conditions should be achievable in both scattered proton beams (i.e. DS) and scanned proton beams (i.e. PBS). However, it is not a priori clear if TRS-398 kQ data, which are based on Monte Carlo (MC) calculations in scattered beams, can be used for scanned beams. Using TOPAS-Geant4 MC simulations, the study aims to determine whether broad beam quality correction factors calculated in TRS-398 can be directly applied to PBS delivery modality. Methods: As reference conditions, we consider a 10×10×10 cm 3 homogeneous dose distribution delivered by PBS system in a water phantom (32/10 cm range/modulation) and an air cavity placed at the center of the spread-out-Bragg-peak. In order to isolate beam differences, a hypothetical broad beam is simulated. This hypothetical beam reproduces exactly the same range modulation, and uses the same energy layers than the PBS field. Ion chamber responses are computed for the PBS and hypothetical beams and then compared. Results: For an air cavity of 2×2×0.2 cm 3 , the ratio of ion chamber responses for the PBS and hypothetical beam qualities is 0.9991 ± 0.0016. Conclusion: Quality correction factors are insensitive to the delivery pattern of the beam (broad beam or PBS), as long as similar dose distributions are achieved. This investigation, for an air cavity, suggests that broad beam quality correction factors published in TRS-398 can be applied for scanned beams. J. Sorriaux is financially supported by a public-private partnership involving the company Ion Beam Applications (IBA)

  13. Monte Carlo calculations of electron beam quality conversion factors for several ion chamber types

    Energy Technology Data Exchange (ETDEWEB)

    Muir, B. R., E-mail: Bryan.Muir@nrc-cnrc.gc.ca [Measurement Science and Standards, National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario K1A 0R6 (Canada); Rogers, D. W. O., E-mail: drogers@physics.carleton.ca [Carleton Laboratory for Radiotherapy Physics, Physics Department, Carleton University, 1125 ColonelBy Drive, Ottawa, Ontario K1S 5B6 (Canada)

    2014-11-01

    Purpose: To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations of the response of 10 plane-parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on the determination of the optimal shift of the chambers’ effective point of measurement (EPOM) and beam quality conversion factors. Methods: The EGSnrc system is used for calculations of the absorbed dose to gas in ion chamber models and the absorbed dose to water as a function of depth in a water phantom on which cobalt-60 and several electron beam source models are incident. The optimal EPOM shifts of the ion chambers are determined by comparing calculations of R{sub 50} converted from I{sub 50} (calculated using ion chamber simulations in phantom) to R{sub 50} calculated using simulations of the absorbed dose to water vs depth in water. Beam quality conversion factors are determined as the calculated ratio of the absorbed dose to water to the absorbed dose to air in the ion chamber at the reference depth in a cobalt-60 beam to that in electron beams. Results: For most plane-parallel chambers, the optimal EPOM shift is inside of the active cavity but different from the shift determined with water-equivalent scaling of the front window of the chamber. These optimal shifts for plane-parallel chambers also reduce the scatter of beam quality conversion factors, k{sub Q}, as a function of R{sub 50}. The optimal shift of cylindrical chambers is found to be less than the 0.5 r{sub cav} recommended by current dosimetry protocols. In most cases, the values of the optimal shift are close to 0.3 r{sub cav}. Values of k{sub ecal} are calculated and compared to those from the TG-51 protocol and differences are explained using accurate individual correction factors for a subset of ion chambers investigated. High-precision fits to beam quality conversion factors normalized to unity in a beam with R{sub 50} = 7.5 cm (k{sub Q}{sup ′}) are provided. These

  14. Monte Carlo calculations of kQ, the beam quality conversion factor

    International Nuclear Information System (INIS)

    Muir, B. R.; Rogers, D. W. O.

    2010-01-01

    Purpose: To use EGSnrc Monte Carlo simulations to directly calculate beam quality conversion factors, k Q , for 32 cylindrical ionization chambers over a range of beam qualities and to quantify the effect of systematic uncertainties on Monte Carlo calculations of k Q . These factors are required to use the TG-51 or TRS-398 clinical dosimetry protocols for calibrating external radiotherapy beams. Methods: Ionization chambers are modeled either from blueprints or manufacturers' user's manuals. The dose-to-air in the chamber is calculated using the EGSnrc user-code egs c hamber using 11 different tabulated clinical photon spectra for the incident beams. The dose to a small volume of water is also calculated in the absence of the chamber at the midpoint of the chamber on its central axis. Using a simple equation, k Q is calculated from these quantities under the assumption that W/e is constant with energy and compared to TG-51 protocol and measured values. Results: Polynomial fits to the Monte Carlo calculated k Q factors as a function of beam quality expressed as %dd(10) x and TPR 10 20 are given for each ionization chamber. Differences are explained between Monte Carlo calculated values and values from the TG-51 protocol or calculated using the computer program used for TG-51 calculations. Systematic uncertainties in calculated k Q values are analyzed and amount to a maximum of one standard deviation uncertainty of 0.99% if one assumes that photon cross-section uncertainties are uncorrelated and 0.63% if they are assumed correlated. The largest components of the uncertainty are the constancy of W/e and the uncertainty in the cross-section for photons in water. Conclusions: It is now possible to calculate k Q directly using Monte Carlo simulations. Monte Carlo calculations for most ionization chambers give results which are comparable to TG-51 values. Discrepancies can be explained using individual Monte Carlo calculations of various correction factors which are more

  15. SU-F-BRD-15: Quality Correction Factors in Scanned Or Broad Proton Therapy Beams Are Indistinguishable

    Energy Technology Data Exchange (ETDEWEB)

    Sorriaux, J; Lee, J [Molecular Imaging Radiotherapy & Oncology, Universite Catholique de Louvain, Brussels (Belgium); ICTEAM Institute, Universite catholique de Louvain, Louvain-la-Neuve (Belgium); Testa, M; Paganetti, H [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, Massachusetts (United States); Bertrand, D; Orban de Xivry, J [Ion Beam Applications, Louvain-la-neuve, Brabant Wallon (Belgium); Palmans, H [EBG MedAustron GmbH, Wiener Neustadt (Austria); National Physical Laboratory, Teddington (United Kingdom); Vynckier, S [Cliniques Universitaires Saint-Luc, Brussels (Belgium); Sterpin, E [Molecular Imaging Radiotherapy & Oncology, Universite Catholique de Louvain, Brussels (Belgium)

    2015-06-15

    Purpose: The IAEA TRS-398 code of practice details the reference conditions for reference dosimetry of proton beams using ionization chambers and the required beam quality correction factors (kQ). Pencil beam scanning (PBS) requires multiple spots to reproduce the reference conditions. The objective is to demonstrate, using Monte Carlo (MC) calculations, that kQ factors for broad beams can be used for scanned beams under the same reference conditions with no significant additional uncertainty. We consider hereafter the general Alfonso formalism (Alfonso et al, 2008) for non-standard beam. Methods: To approach the reference conditions and the associated dose distributions, PBS must combine many pencil beams with range modulation and shaping techniques different than those used in passive systems (broad beams). This might lead to a different energy spectrum at the measurement point. In order to evaluate the impact of these differences on kQ factors, ion chamber responses are computed with MC (Geant4 9.6) in a dedicated scanned pencil beam (Q-pcsr) producing a 10×10cm2 composite field with a flat dose distribution from 10 to 16 cm depth. Ion chamber responses are also computed by MC in a broad beam with quality Q-ds (double scattering). The dose distribution of Q -pcsr matches the dose distribution of Q-ds. k-(Q-pcsr,Q-ds) is computed for a 2×2×0.2cm{sup 3} idealized air cavity and a realistic plane-parallel ion chamber (IC). Results: Under reference conditions, quality correction factors for a scanned composite field versus a broad beam are the same for air cavity dose response, k-(Q-pcsr,Q-ds) =1.001±0.001 and for a Roos IC, k-(Q-pcsr,Q-ds) =0.999±0.005. Conclusion: Quality correction factors for ion chamber response in scanned and broad proton therapy beams are identical under reference conditions within the calculation uncertainties. The results indicate that quality correction factors published in IAEA TRS-398 can be used for scanned beams in the SOBP of a

  16. SU-F-BRD-15: Quality Correction Factors in Scanned Or Broad Proton Therapy Beams Are Indistinguishable

    International Nuclear Information System (INIS)

    Sorriaux, J; Lee, J; Testa, M; Paganetti, H; Bertrand, D; Orban de Xivry, J; Palmans, H; Vynckier, S; Sterpin, E

    2015-01-01

    Purpose: The IAEA TRS-398 code of practice details the reference conditions for reference dosimetry of proton beams using ionization chambers and the required beam quality correction factors (kQ). Pencil beam scanning (PBS) requires multiple spots to reproduce the reference conditions. The objective is to demonstrate, using Monte Carlo (MC) calculations, that kQ factors for broad beams can be used for scanned beams under the same reference conditions with no significant additional uncertainty. We consider hereafter the general Alfonso formalism (Alfonso et al, 2008) for non-standard beam. Methods: To approach the reference conditions and the associated dose distributions, PBS must combine many pencil beams with range modulation and shaping techniques different than those used in passive systems (broad beams). This might lead to a different energy spectrum at the measurement point. In order to evaluate the impact of these differences on kQ factors, ion chamber responses are computed with MC (Geant4 9.6) in a dedicated scanned pencil beam (Q-pcsr) producing a 10×10cm2 composite field with a flat dose distribution from 10 to 16 cm depth. Ion chamber responses are also computed by MC in a broad beam with quality Q-ds (double scattering). The dose distribution of Q -pcsr matches the dose distribution of Q-ds. k-(Q-pcsr,Q-ds) is computed for a 2×2×0.2cm 3 idealized air cavity and a realistic plane-parallel ion chamber (IC). Results: Under reference conditions, quality correction factors for a scanned composite field versus a broad beam are the same for air cavity dose response, k-(Q-pcsr,Q-ds) =1.001±0.001 and for a Roos IC, k-(Q-pcsr,Q-ds) =0.999±0.005. Conclusion: Quality correction factors for ion chamber response in scanned and broad proton therapy beams are identical under reference conditions within the calculation uncertainties. The results indicate that quality correction factors published in IAEA TRS-398 can be used for scanned beams in the SOBP of a high

  17. Simulation study of the photon quality correction factors of ionization chambers for FiR 1 epithermal neutron beam

    International Nuclear Information System (INIS)

    Koivunoro, H.; Uusi-Simola, J.; Savolainen, S.; Kotiluoto, P.; Auterinen, I.; Kosunen, A.

    2006-01-01

    At FiR 1 BNCT facility in Finland, neutron-insensitive Mg(Ar) ionization chambers are used for photon dose measurements in an epithermal neutron beam. Previously, photon sensitivity factors for the chamber for the measurements in a water phantom in FiR 1 beam have been determined experimentally from measurements in 60 Co gamma and in a 6 MV clinical accelerator photon beams. However, the response of the ionization chamber in a water phantom depends on energy spectrum and angle of the photons and the secondary electrons created inside the phantom and may differ depending on type of the irradiation source (accelerator vs. an epithermal neutron beam). Also, the experimental sensitivity factor does not take into account the possible perturbations in the photon production in phantom caused by the ionization chamber materials. Therefore, it is necessary to determine the photon quality correction factors (k Qγ ) for the Mg(Ar) chamber at the FiR 1 beam through computer simulations. In this study, the k Qγ factors have been determined for Mg(Ar) chamber from Monte Carlo calculations of absorbed photon dose at two depths in a water phantom using MCNP code. The k qγ factors obtained with this method are compared to the sensitivity factors determined with measurements in an accelerator photon beam and to the k Qγ factors published previously. (author)

  18. Interface circuit for a multiple-beam tuning-fork gyroscope with high quality factors

    Science.gov (United States)

    Wang, Ren

    This research work presents the design, theoretical analysis, fabrication, interface electronics, and experimental results of a Silicon-On-Insulator (SOI) based Multiple-Beam Tuning-Fork Gyroscope (MB-TFG). Based on a numerical model of Thermo-Elastic Damping (TED), a Multiple-Beam Tuning-Fork Structure (MB-TFS) is designed with high Quality factors (Qs) in its two operation modes. A comprehensive theoretical analysis of the MB-TFG design is conducted to relate the design parameters to its operation parameters and further performance parameters. In conjunction with a mask that defines the device through trenches to alleviate severe fabrication effect on anchor loss, a simple one-mask fabrication process is employed to implement this MB-TFG design on SOI wafers. The fabricated MB-TFGs are tested with PCB-level interface electronics and a thorough comparison between the experimental results and a theoretical analysis is conducted to verify the MB-TFG design and accurately interpret the measured performance. The highest measured Qs of the fabricated MB-TFGs in vacuum are 255,000 in the drive-mode and 103,000 in the sense-mode, at a frequency of 15.7kHz. Under a frequency difference of 4Hz between the two modes (operation frequency is 16.8kHz) and a drive-mode vibration amplitude of 3.0um, the measured rate sensitivity is 80mVpp/°/s with an equivalent impedance of 6MQ. The calculated overall rate resolution of this device is 0.37/hrhiElz, while the measured Angle Random Walk (ARW) and bias instability are 6.67°/'vhr and 95°/hr, respectively.

  19. Experimental determination of the beam quality dependence factors, kQ, for ionization chambers used in photon and electron dosimetry

    International Nuclear Information System (INIS)

    Guerra, A.S.; Laitano, R.F.; Pimpinella, M.

    1995-01-01

    Dosimetry in radiotherapy with ionization chambers calibrated in 60 Co gamma beams in terms of absorbed dose to water, D W , can be performed if a factor conventionally denoted as k Q is known. The factor k Q depends on the beam quality and the chamber characteristics. Calculated values of the k Q factors for many types of ionization chamber have been recently published. In this work the experimental determination of the k Q factors for various ionization chambers was performed for 6 MV and 15 MV photon beams and for a 14 MeV electron beam. The k Q factors were determined by a procedure based on relative measurements performed with the ionization chamber and ferrous sulphate solution in 60 Co gamma radiation and accelerator beams, respectively. The experimental k Q values are compared with the calculated values so far published. Theoretical and experimental k Q values are in fairly good agreement. The uncertainty in the experimental k Q factors determined in this work is less than about 1%, that is, appreciably smaller than the uncertainty of about 1.5% reported for the calculated values. (Author)

  20. Correction factors for photon beam quality for cylindrical ionization chambers: Monte Carlo calculations by using the PENELOPE code

    International Nuclear Information System (INIS)

    Barreras Caballero, A. A.; Hernandez Garcia, J.J.; Alfonso Laguardia, R.

    2009-01-01

    Were directly determined correction factors depending on the type camera beam quality, k, Q, and kQ, Qo, instead of the product (w, air p) Q, for three type cylindrical ionization chambers Pinpoint and divergent monoenergetic beams of photons in a wide range of energies (4-20 MV). The method of calculation used dispenses with the approaches taken in the classic procedure considered independent of braking power ratios and the factors disturbance of the camera. A detailed description of the geometry and materials chambers were supplied by the manufacturer and used as data input for the system 2006 of PENELOPE Monte Carlo calculation using a User code that includes correlated sampling, and forced interactions division of particles. We used a photon beam Co-60 as beam reference for calculating the correction factors for beam quality. No data exist for the cameras PTW 31014, 31015 and 31016 in the TRS-398 at they do not compare the results with data calculated or determined experimentally by other authors. (author)

  1. Medium-Term Stability of the Photon Beam Energy of An Elekta CompactTM Linear Accelerator Based on Daily Measurements of Beam Quality Factor

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Mosleh-Shirazi

    2016-04-01

    Full Text Available Introduction In this study, we aimed to assess the medium-term energy stability of a 6MV Elekta CompactTM linear accelerator. To the best of our knowledge, this is the first published article to evaluate this linear accelerator in terms of energy stability. As well as investigating the stability of the linear accelerator energy over a period of several weeks, the results will be useful for estimation of the required tolerance values for the beam quality factor (BQF of the PTW QUICKCHECK weblineTM (QCW daily checking device. Materials and Methods Over a 13 week period of routine clinical service, 52 daily readings of BQF were taken and then analyzed for a 10×10 cm2 field. Results No decreasing or increasing trend in BQF was observed over the study period. The mean BQF value was estimated at 5.4483 with a standard deviation (SD of 0.0459 (0.8%. The mean value was only 0.1% different from the baseline value. Conclusion The results of this medium-term stability study of the Elekta Compact linear accelerator energy showed that 96.2% of the observed BQF values were within ±1.3% of the baseline value. This can be considered to be within the recommended tolerance for linear accelerator photon beam energy. If an approach of applying ±3 SD is taken, the tolerance level for BQF may be suggested to be set at ±2.5%. However, further research is required to establish a relationship between BQF value and the actual changes in beam energy and penetrative quality.

  2. Quality factors

    International Nuclear Information System (INIS)

    Kerr, G.D.

    1986-01-01

    The quality factor, Q, is a dimensionless modifier used in converting absorbed dose, expressed in rads (or grays), to dose equivalent, expressed in rems (or seiverts). The dose equivalent is used in radiation protection to account for the biological effectiveness of different kinds of radiation. The quality factor is related to both the linear energy transfer (LET) and relative biological effectiveness (RBE). The RBE's obtained from biological experiments depend in a complex way on the observed biological effect, the specific test organism, and the experimental conditions. Judgement is involved, therefore, in the choice of the quality factor. Questions regarding the adequacy of current Q values for neutrons were raised first in a 1980 statement by the National Council on Radiation Protection (NCRP) and later in a 1985 statement by the International Commission on Radiological Protection (ICRP). In 1980, the NCRP alerted the technical community to possible future increases between a factor of three and ten in the Q for neutrons, and in 1985, the ICRP suggested an increase by a factor of two in Q for neutrons. Both the ICRP and NRCP are now recommending essentially the same guidance with regard to Q for neutrons: an increase by a factor of two. The Q for neutrons is based on a large, albeit unfocused, body of experimental data. In spite of the lack of focus, the data supporting a change in the neutron quality factor are substantial. However, the proposed doubling of Q for neutrons is clouded by other issues regarding its application. 33 refs., 4 figs., 6 tabs

  3. Experimental determination of beam quality factors, kQ, for two types of Farmer chamber in a 10 MV photon and a 175 MeV proton beam.

    Science.gov (United States)

    Medin, Joakim; Ross, Carl K; Klassen, Norman V; Palmans, Hugo; Grusell, Erik; Grindborg, Jan-Erik

    2006-03-21

    Absorbed doses determined with a sealed water calorimeter operated at 4 degrees C are compared with the results obtained using ionization chambers and the IAEA TRS-398 code of practice in a 10 MV photon beam (TPR(20,10) = 0.734) and a 175 MeV proton beam (at a depth corresponding to the residual range, R(res) = 14.7 cm). Three NE 2571 and two FC65-G ionization chambers were calibrated in terms of absorbed-dose-to-water in (60)Co at the Swedish secondary standard dosimetry laboratory, directly traceable to the BIPM. In the photon beam quality, calorimetry was found to agree with ionometry within 0.3%, confirming the k(Q) values tabulated in TRS-398. In contrast, a 1.8% deviation was found in the proton beam at 6 g cm(-2) depth, suggesting that the TRS-398 tabulated k(Q) values for these two ionization chamber types are too high. Assuming no perturbation effect in the proton beam for the ionization chambers, a value for (w(air)/e)(Q) of 33.6 J C(-1) +/- 1.7% (k = 1) can be derived from these measurements. An analytical evaluation of the effect from non-elastic nuclear interactions in the ionization chamber wall indicates a perturbation effect of 0.6%. Including this estimated result in the proton beam would increase the determined (w(air)/e)(Q) value by the same amount.

  4. A better beam quality

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Progress has been made on two fronts, providing physics data and preparing for higher intensities. Over the Whitsun weekend of May 22 to 24, 5 fills for physics provided almost 30 hours of stable colliding beams, all with bunch intensities around 2x1010 protons and at a β* of 2m. The first three of these fills were with 6 bunches per beam, giving 3 pairs of collisions in all experiments. For the other two fills, the number of bunches per beam was increased to 13, giving 8 pairs of colliding bunches, and for the first time luminosities were pushed above 1029 cm-2s-1, 2 orders of magnitude higher than first collisions in March. In between and after these physics fills, nominal bunches of 1011 protons were successfully ramped and brought into collision in ATLAS and CMS for the first time (not in stable beam conditions and without squeeze). Event rates seen by the experiments were in the expected range for these conditions. In the middle of this work, a short fill with beams of 7 nominal bunches was ...

  5. In situ measurement of laser beam quality

    Science.gov (United States)

    Hashemi, Somayeh Sadat; Ghavami Sabouri, Saeed; Khorsandi, Alireza

    2017-09-01

    An innovative optical method is introduced for the beam quality measurement of any arbitrary transverse mode based on the reconstruction of the mode from a few-frame image of the beam cross-section. This is performed by the decomposition of a mode to its basic Hermite-Gaussian modal coefficients. The performance of the proposed method is examined through M 2-factor measurement of the beam of a Nd:YAG laser which was forced to oscillate in a certain mode using a crossed rectangular intracavity aperture. Obtained results have shown that this method can be alternatively replaced for the hologram- and ISO-based techniques recently exploiting for beam quality measurement regardless of the mode type and the position of utilized CCD camera along the beam direction.

  6. A Beam Quality Monitor for LHC Beams in the SPS

    CERN Document Server

    Papotti, G

    2008-01-01

    The SPS Beam Quality Monitor (BQM) system monitors the longitudinal parameters of the beam before extraction to the LHC to prevent losses and degradation of the LHC luminosity by the injection of low quality beams. It is implemented in two priority levels. At the highest level the SPS-LHC synchronization and global beam structure are verified. If the specifications are not met, the beam should be dumped in the SPS before extraction. On the second level, individual bunch position, length and stability are checked for beam quality assessment. Tolerances are adapted to the mode of operation and extraction to the LHC can also be inhibited. Beam parameters are accessed by acquiring bunch profiles with a longitudinal pick up and fast digital oscilloscope. The beam is monitored for instabilities during the acceleration cycle and thoroughly checked a few ms before extraction for a final decision on extraction interlock. Dedicated hardware and software components implementing fast algorithms are required. In this pape...

  7. Experimental investigation of factors limiting slow axis beam quality in 9xx nm high power broad area diode lasers

    International Nuclear Information System (INIS)

    Winterfeldt, M.; Crump, P.; Wenzel, H.; Erbert, G.; Tränkle, G.

    2014-01-01

    GaAs-based broad-area diode lasers are needed with improved lateral beam parameter product (BPP lat ) at high power. An experimental study of the factors limiting BPP lat is therefore presented, using extreme double-asymmetric (EDAS) vertical structures emitting at 910 nm. Continuous wave, pulsed and polarization-resolved measurements are presented and compared to thermal simulation. The importance of thermal and packaging-induced effects is determined by comparing junction -up and -down devices. Process factors are clarified by comparing diodes with and without index-guiding trenches. We show that in all cases studied, BPP lat is limited by a non-thermal BPP ground-level and a thermal BPP, which depends linearly on self-heating. Measurements as a function of pulse width confirm that self-heating rather than bias-level dominates. Diodes without trenches show low BPP ground-level, and a thermal BPP which depends strongly on mounting, due to changes in the temperature profile. The additional lateral guiding in diodes with trenches strongly increases the BPP ground-level, but optically isolates the stripe from the device edges, suppressing the influence of the thermal profile, leading to a BPP-slope that is low and independent of mounting. Trenches are also shown to initiate strain fields that cause parasitic TM-polarized emission with large BPP lat , whose influence on total BPP lat remains small, provided the overall polarization purity is >95%

  8. Experimental investigation of factors limiting slow axis beam quality in 9xx nm high power broad area diode lasers

    Science.gov (United States)

    Winterfeldt, M.; Crump, P.; Wenzel, H.; Erbert, G.; Tränkle, G.

    2014-08-01

    GaAs-based broad-area diode lasers are needed with improved lateral beam parameter product (BPPlat) at high power. An experimental study of the factors limiting BPPlat is therefore presented, using extreme double-asymmetric (EDAS) vertical structures emitting at 910 nm. Continuous wave, pulsed and polarization-resolved measurements are presented and compared to thermal simulation. The importance of thermal and packaging-induced effects is determined by comparing junction -up and -down devices. Process factors are clarified by comparing diodes with and without index-guiding trenches. We show that in all cases studied, BPPlat is limited by a non-thermal BPP ground-level and a thermal BPP, which depends linearly on self-heating. Measurements as a function of pulse width confirm that self-heating rather than bias-level dominates. Diodes without trenches show low BPP ground-level, and a thermal BPP which depends strongly on mounting, due to changes in the temperature profile. The additional lateral guiding in diodes with trenches strongly increases the BPP ground-level, but optically isolates the stripe from the device edges, suppressing the influence of the thermal profile, leading to a BPP-slope that is low and independent of mounting. Trenches are also shown to initiate strain fields that cause parasitic TM-polarized emission with large BPPlat, whose influence on total BPPlat remains small, provided the overall polarization purity is >95%.

  9. Experimental investigation of factors limiting slow axis beam quality in 9xx nm high power broad area diode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Winterfeldt, M., E-mail: martin.winterfeldt@fbh-berlin.de; Crump, P.; Wenzel, H.; Erbert, G.; Tränkle, G. [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany)

    2014-08-14

    GaAs-based broad-area diode lasers are needed with improved lateral beam parameter product (BPP{sub lat}) at high power. An experimental study of the factors limiting BPP{sub lat} is therefore presented, using extreme double-asymmetric (EDAS) vertical structures emitting at 910 nm. Continuous wave, pulsed and polarization-resolved measurements are presented and compared to thermal simulation. The importance of thermal and packaging-induced effects is determined by comparing junction -up and -down devices. Process factors are clarified by comparing diodes with and without index-guiding trenches. We show that in all cases studied, BPP{sub lat} is limited by a non-thermal BPP ground-level and a thermal BPP, which depends linearly on self-heating. Measurements as a function of pulse width confirm that self-heating rather than bias-level dominates. Diodes without trenches show low BPP ground-level, and a thermal BPP which depends strongly on mounting, due to changes in the temperature profile. The additional lateral guiding in diodes with trenches strongly increases the BPP ground-level, but optically isolates the stripe from the device edges, suppressing the influence of the thermal profile, leading to a BPP-slope that is low and independent of mounting. Trenches are also shown to initiate strain fields that cause parasitic TM-polarized emission with large BPP{sub lat}, whose influence on total BPP{sub lat} remains small, provided the overall polarization purity is >95%.

  10. On beam quality and flatness of radiotherapy megavoltage photon beams

    International Nuclear Information System (INIS)

    Hossain, Murshed; Rhoades, Jeffrey

    2016-01-01

    Ratio of percentage depth dose (PDD) at two depths, PDD at a depth of 10 cm (PDD 10 ), and beam flatness are monitored regularly for radiotherapy beams for quality assurance. The purpose of this study is to understand the effects of changes in one of these parameters on the other. Is it possible to monitor only the beam flatness and not PDD? The investigation has two components. Naturally occurring i.e., unintended changes in PDD ratio and in-plane flatness for 6 and 10 MV photon beams for one particular Siemens Artiste Linac are monitored for a period of about 4 years. Secondly, deliberate changes in the beam parameters are induced by changing the bending magnet current (BMI). Relationships between various beam parameters for unintended changes as well as deliberate changes are characterized. Long term unintentional changes of PDD ratio are found to have no systematic trend. The flatness in the in plane direction for 6 and 10 MV beams show slow increase of 0.43 and 0.75 % respectively in about 4 years while the changes in the PDD ratio show no such trend. Over 10 % changes in BMI are required to induce changes in the beam quality indices at 2 % level. PDD ratio for the 10 MV beam is found to be less sensitive, while the depth of maximum dose, d max , is more sensitive to the changes in BMI compared to the 6 MV beam. Tolerances are more stringent for PDD 10 than PDD ratio for the 10 MV beam. PDD ratio, PDD 10 , and flatness must be monitored independently. Furthermore, off axis ratio alone cannot be used to monitor flatness. The effect of beam quality change in the absolute dose is clinically insignificant.

  11. Influence of mode competition on beam quality of fiber amplifier

    International Nuclear Information System (INIS)

    Xiao Qi-Rong; Yan Ping; Sun Jun-Yi; Chen Xiao; Ren Hai-Cui; Gong Ma-Li

    2014-01-01

    Theoretical and experimental studies of the influence of the mode competition on the output beam quality of fiber amplifiers are presented. Rate equations and modal decomposition method are used in the theoretical model. In the experiment, the output beam-quality factor of a fiber amplifier, which is based on a Yb-doped double-clad large mode area fiber as a function of the seed beam quality and the pump power of the amplifier, is measured. The experimental results are consistent with the theoretical analysis. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  12. Measurement system with high accuracy for laser beam quality.

    Science.gov (United States)

    Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

    2015-05-20

    Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%.

  13. Improvement of the beam quality of a diode laser with two active broad-area segments

    DEFF Research Database (Denmark)

    Chi, Mingjun; Thestrup, B.; Mortensen, J.L.

    2003-01-01

    The beam quality of a diode laser with two active segments was improved using an external cavity with collimating optics, a grating, and an output coupler. The beam quality of the output beam, which is the first-order diffractive beam from the grating, was improved by a factor of 2, and at least...... half of the freely running power of the laser was coupled out from the external cavity. The output power can be enhanced further by the feedback from the zeroth-order beam. The possibility of improving the beam quality further is discussed and a new double-external-cavity configuration is suggested....

  14. Average spreading and beam quality evolution of Gaussian array beams propagating through oceanic turbulence

    International Nuclear Information System (INIS)

    Zhi, Dong; Chen, Yizhu; Tao, Rumao; Ma, Yanxing; Zhou, Pu; Si, Lei

    2015-01-01

    The propagation properties of a radial Gaussian beam array through oceanic turbulence are studied analytically. The analytical expressions for the average intensity and the beam quality (power-in-the-bucket (PIB) and M 2 -factor) of a radial beam array in a turbulent ocean are derived based on an account of statistical optics methods, the extended Huygens-Fresnel principle, and the second order moments of the Wigner distribution function. The influences of w, ε, and χ T on the average intensity are investigated. The array divergence increases and the laser beam spreads as the salinity-induced dominant, ε decreased, and χ T increased. Further, the analytical expression of PIB and the M 2 -factor in the target plane is obtained. The changes of PIB and the M 2 -factor with three oceanic turbulence parameters indicate that the stronger turbulence with a larger w, smaller ε, and larger χ T results in the value of PIB decreasing, the value of the M 2 -factor increasing, and the beam quality degrading. (letter)

  15. LHC Injection Beam Quality During LHC Run I

    CERN Document Server

    AUTHOR|(CDS)2079186; Kain, Verena; Stapnes, Steinar

    The LHC at CERN was designed to accelerate proton beams from 450 GeV to 7 TeV and collide them in four large experiments. The 450 GeV beam is extracted from the last pre-accelerator, the SPS, and injected into the LHC via two 3 km long transfer lines, TI 2 and TI 8. The injection process is critical in terms of preservation of beam quality and machine protection. During LHC Run I (2009-2013) the LHC was filled with twelve high intensity injections per ring, in batches of up to 144 bunches of 1.7*10^11 protons per bunch. The stored beam energy of such a batch is already an order of magnitude above the damage level of accelerator equipment. Strict quality and machine protection requirements at injection have a significant impact on operational efficiency. During the first years of LHC operation, the injection phase was identified as one of the limiting factors for fast LHC turnaround time. The LHC Injection Quality Check (IQC) software framework was developed as a part of this thesis to monitor the beam quality...

  16. Beam-scanning system for determination of beam profiles and form factors in merged-beam experiments

    International Nuclear Information System (INIS)

    Keyser, C.J.; Froelich, H.R.; Mitchell, J.B.A.; McGowan, J.W.

    1979-01-01

    A beam-scanning system for a merged electron-ion beam experiment is described. This system is used to determine the horizontal and vertical beam profiles and the form factors at three different locations along the axis of the beams. Design details of the wedge-shaped scanners and the electronic circuit for obtaining beam profiles and form factors are described. The form factor derivation for merged beams is given and an expression in terms of measured quantities is derived. (author)

  17. A laser beam quality definition based on induced temperature rise.

    Science.gov (United States)

    Miller, Harold C

    2012-12-17

    Laser beam quality metrics like M(2) can be used to describe the spot sizes and propagation behavior of a wide variety of non-ideal laser beams. However, for beams that have been diffracted by limiting apertures in the near-field, or those with unusual near-field profiles, the conventional metrics can lead to an inconsistent or incomplete description of far-field performance. This paper motivates an alternative laser beam quality definition that can be used with any beam. The approach uses a consideration of the intrinsic ability of a laser beam profile to heat a material. Comparisons are made with conventional beam quality metrics. An analysis on an asymmetric Gaussian beam is used to establish a connection with the invariant beam propagation ratio.

  18. Using Target Ablation for Ion Beam Quality Improvement

    International Nuclear Information System (INIS)

    Zhao Shuan; Chen Jia-Er; Lin Chen; Ma Wen-Jun; Yan Xue-Qing; Wang Jun-Jie

    2016-01-01

    During the laser foil interaction, the output ion beam quality including the energy spread and beam divergence can be improved by the target ablation, due to the direct laser acceleration (DLA) electrons generated in the ablation plasma. The acceleration field established at the target rear by these electrons, which is highly directional and triangle-envelope, is helpful for the beam quality. With the help of the target ablation, both the beam divergence and energy spread will be reduced. If the ablation is more sufficient, the impact of DLA-electron-caused field will be strengthened, and the beam quality will be better, confirmed by the particle-in-cell simulation. (paper)

  19. Minimal requirements for quality controls in radiotherapy with external beams

    International Nuclear Information System (INIS)

    1999-01-01

    Physical dosimetric guidelines have been developed by the Italian National Institute of Health study group on quality assurance in radiotherapy to define protocols for quality controls in external beam radiotherapy. While the document does not determine strict rules or firm recommendations, it suggests minimal requirements for quality controls necessary to guarantee an adequate degree of accuracy in external beam radiotherapy [it

  20. Neutron quality factor

    International Nuclear Information System (INIS)

    1995-06-01

    Both the International Commission on Radiological Protection (ICRP) and the National Council on Radiation Protection and Measurements (NCRP) have recommended that the radiation quality weighting factor for neutrons (Q n , or the corresponding new modifying factor, w R ) be increased by a value of two for most radiation protection practices. This means an increase in the recommended value for Q n from a nominal value of 10 to a nominal value of 20. This increase may be interpreted to mean that the biological effectiveness of neutrons is two times greater than previously thought. A decision to increase the value of Q n will have a major impact on the regulations and radiation protection programs of Federal agencies responsible for the protection of radiation workers. Therefore, the purposes of this report are: (1) to examine the general concept of open-quotes quality factorclose quotes (Q) in radiation protection and the rationale for the selection of specific values of Q n ; and (2) to make such recommendations to the Federal agencies, as appropriate. This report is not intended to be an exhaustive review of the scientific literature on the biological effects of neutrons, with the aim of defending a particular value for Q n . Rather, the working group examined the technical issues surrounding the current recommendations of scientific advisory bodies on this matter, with the aim of determining if these recommendations should be adopted by the Federal agencies. Ultimately, the group concluded that there was no compelling basis for a change in Q n . The report was prepared by Federal scientists working under the auspices of the Science Panel of the Committee on Interagency Radiation Research and Policy Coordination (CIRRPC)

  1. Factors Affecting Medical Service Quality.

    Science.gov (United States)

    Mosadeghrad, Ali Mohammad

    2014-02-01

    A better understanding of factors influencing quality of medical service can pinpoint better strategies for quality assurance in medical services. This study aimed to identify factors affecting the quality of medical services provided by Iranian physicians. Exploratory in-depth individual interviews were conducted with sixty-four physicians working in various medical institutions in Iran. Individual, organizational and environmental factors enhance or inhibit the quality of medical services. Quality of medical services depends on the personal factors of the physician and patient, and factors pertaining to the healthcare setting and the broader environment. Differences in internal and external factors such as availability of resources, patient cooperation and collaboration among providers affect the quality of medical services and patient outcomes. Supportive leadership, proper planning, education and training and effective management of resources and processes improve the quality of medical services. This article contributes to healthcare theory and practice by developing a conceptual framework for understanding factors that influence medical services quality.

  2. Flattening filter free beams from TrueBeam and Versa HD units: Evaluation of the parameters for quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Fogliata, Antonella, E-mail: antonella.fogliata@humanitas.it; Reggiori, Giacomo; Stravato, Antonella; Scorsetti, Marta; Cozzi, Luca [Radiotherapy and Radiosurgery Department, Humanitas Research Hospital, Milan-Rozzano I-20098 (Italy); Fleckenstein, Jens; Schneider, Frank; Lohr, Frank [Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim D-68167 (Germany); Pachoud, Marc; Ghandour, Sarah [Radiation Oncology Department, Hôpital Riviera Chablais, Vevey CH-1800 (Switzerland); Krauss, Harald [Radio-Oncology Department, Kaiser Franz Josef Spital, Vienna A-1100 (Austria)

    2016-01-15

    Purpose: Flattening filter free (FFF) beams generated by medical linear accelerators are today clinically used for stereotactical and non-stereotactical radiotherapy treatments. Such beams differ from the standard flattened beams (FF) in the high dose rate and the profile shape peaked on the beam central axis. Definition of new parameters as unflatness and slope for FFF beams has been proposed based on a renormalization factor for FFF profiles. The present study aims to assess the dosimetric differences between FFF beams generated by linear accelerators from different vendors, and to provide renormalization and parameter data of the two kinds of units. Methods: Dosimetric data from two Varian TrueBeam and two Elekta Versa HD linear accelerators, all with 6 and 10 MV nominal accelerating potentials, FF and FFF modes have been collected. Renormalization factors and related fit parameters according to Fogliata et al. [“Definition of parameters for quality assurance of flattening filter free (FFF) photon beams in radiation therapy,” Med. Phys. 39, 6455–6464 (2012)] have been evaluated for FFF beams of both units and energies. Unflatness and slope parameters from profile curves were evaluated. Dosimetric differences in terms of beam penetration and near-the-surface dose were also assessed. Results: FFF profile parameters have been updated; renormalization factors and unflatness from the Varian units are consistent with the published data. Elekta FFF beam qualities, different from the Varian generated beams, tend to express similar behaviour as the FF beam of the corresponding nominal energy. TPR{sub 20,10} for 6 and 10 MV FF and FFF TrueBeam beams are 0.665, 0.629 (6 MV) and 0.738, 0.703 (10 MV). The same figures for Versa HD units are 0.684, 0.678 (6 MV) and 0.734, 0.721 (10 MV). Conclusions: Renormalization factor and unflatness parameters evaluated from Varian and Elekta FFF beams are provided, in particular renormalization factors table and fit parameters.

  3. Evaluation of thermal effects on the beam quality of disk laser with unstable resonator

    Science.gov (United States)

    Shayganmanesh, Mahdi; Beirami, Reza

    2017-01-01

    In this paper thermal effects of the disk active medium and associated effects on the beam quality of laser are investigated. Using Collins integral and iterative method, transverse mode of an unstable resonator including a Yb:YAG active medium in disk geometry is calculated. After that the beam quality of the laser is calculated based on the generalized beam characterization method. Thermal lensing of the disk is calculated based on the OPD (Optical Path Difference) concept. Five factors influencing the OPD including temperature gradient, disk thermal expansion, photo-elastic effect, electronic lens and disk deformation are considered in our calculations. The calculations show that the effect of disk deformation factor on the quality of laser beam in the resonator is strong. However the total effect of all the thermal factors on the internal beam quality is fewer. Also it is shown that thermal effects degrade the output power, beam profile and beam quality of the output laser beam severely. As well the magnitude of each of affecting factors is evaluated distinctly.

  4. Summary Of Session 4: How Do We Monitor Beam Quality?

    Energy Technology Data Exchange (ETDEWEB)

    Karantzoulis, E

    2001-07-01

    Up to the end of the 80's beam quality was mainly believed to be connected only to the intensity i.e. beam quantity. However, with the new colliders already functioning or programmed, new and more (also in safety) demanding production machines (e.g. isotope) and the many new 3rd generation synchrotron radiation sources that accommodate many experimental lines, the beam quality (BQ) issue has to be re-examined, re-evaluated and re-defined. (author)

  5. Summary Of Session 4: How Do We Monitor Beam Quality?

    Energy Technology Data Exchange (ETDEWEB)

    Karantzoulis, E

    2001-07-01

    Up to the end of the 80's beam quality was mainly believed to be connected only to the intensity i.e. beam quantity. However, with the new colliders already functioning or programmed, new and more (also in safety) demanding production machines (e.g. isotope) and the many new 3rd generation synchrotron radiation sources that accommodate many experimental lines, the beam quality (BQ) issue has to be re-examined, re-evaluated and re-defined. (author)

  6. Summary Of Session 4: How Do We Monitor Beam Quality?

    International Nuclear Information System (INIS)

    Karantzoulis, E.

    2001-01-01

    Up to the end of the 80's beam quality was mainly believed to be connected only to the intensity i.e. beam quantity. However, with the new colliders already functioning or programmed, new and more (also in safety) demanding production machines (e.g. isotope) and the many new 3rd generation synchrotron radiation sources that accommodate many experimental lines, the beam quality (BQ) issue has to be re-examined, re-evaluated and re-defined. (author)

  7. Measuring Beam Quality of Hollow Core Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Shephard, J.D.; Roberts, John; Jones, J.D.C.

    2006-01-01

    In this paper, the authors measure the quality of the delivered beam from hollow core photonic crystal fibers (HC-PCFs). The$M^2$parameter is determined, and the near- to far-field transition is examined. The influence on these properties due to the presence of a core surround mode is evaluated.......17 for the same output beam. This highlights the need for careful consideration when measuring and describing the beam quality delivered by these novel photonic fibers....

  8. Numerical determination of injector design for high beam quality

    International Nuclear Information System (INIS)

    Boyd, J.K.

    1985-01-01

    The performance of a free electron laser strongly depends on the electron beam quality or brightness. The electron beam is transported into the free electron laser after it has been accelerated to the desired energy. Typically the maximum beam brightness produced by an accelerator is constrained by the beam brightness deliverd by the accelerator injector. Thus it is important to design the accelerator injector to yield the required electron beam brightness. The DPC (Darwin Particle Code) computer code has been written to numerically model accelerator injectors. DPC solves for the transport of a beam from emission through acceleration up to the full energy of the injector. The relativistic force equation is solved to determine particle orbits. Field equations are solved for self consistent electric and magnetic fields in the Darwin approximation. DPC has been used to investigate the beam quality consequences of A-K gap, accelerating stress, electrode configuration and axial magnetic field profile

  9. Air Quality Monitoring with Routine Utilization of Ion Beam Analysis

    International Nuclear Information System (INIS)

    Wegrzynek, D.

    2013-01-01

    Full text: Information on source contributions to ambient air particulate concentrations is a vital tool for air quality management. Traditional gravimetric analysis of airborne particulate matter is unable to provide information on the sources contributing to air particulate concentrations. Ion beam analysis is used to identify the elemental composition of air particulates for source apportionment and determining the relative contribution of biogenic and anthropogenic sources to air particulate pollution. The elemental composition is obtained by proton induced X-ray emission technique (PIXE), which is an ion beam analysis (IBA) technique. The element concentrations are deduced from the X ray spectra produced when the particulate collected on a filter is bombarded with a high-energy proton beam. As part of the UNDP/IAEA/RCA Project RAS/8/082 ‘Better Management of the Environment, Natural Resources and Industrial Growth through Isotope and Radiation Technology,’ a collaborative alliance was formed between the Institute of Geological and Nuclear Sciences Limited and the Wellington Regional Council, New Zeland [1]. The purpose of the project was to examine the elemental composition of air particulate matter and determine the origins through source apportionment techniques. In New Zealand PM 10 and PM 2.5 fractions have been collected at the industrial area of Seaview, Wellington over two years using a GENT stacked filter unit sampler. Concentrations of elements with atomic mass above neon were determined using ion beam analysis and elemental carbon concentrations were determined using a reflectometer. Specific ambient source elemental 'fingerprints' were then determined by factor analysis and the relative contributions of various local and regional sources were assessed. The significant factors (sources) were determined to be sea salt, soil, industry, and combustion sources. Local industry was found to contribute to ambient lead concentrations. (author)

  10. Feasibility of using a dose-area product ratio as beam quality specifier for photon beams with small field sizes.

    Science.gov (United States)

    Pimpinella, Maria; Caporali, Claudio; Guerra, Antonio Stefano; Silvi, Luca; De Coste, Vanessa; Petrucci, Assunta; Delaunay, Frank; Dufreneix, Stéphane; Gouriou, Jean; Ostrowsky, Aimé; Rapp, Benjamin; Bordy, Jean-Marc; Daures, Josiane; Le Roy, Maïwenn; Sommier, Line; Vermesse, Didier

    2018-01-01

    To investigate the feasibility of using the ratio of dose-area product at 20 cm and 10 cm water depths (DAPR 20,10 ) as a beam quality specifier for radiotherapy photon beams with field diameter below 2 cm. Dose-area product was determined as the integral of absorbed dose to water (D w ) over a surface larger than the beam size. 6 MV and 10 MV photon beams with field diameters from 0.75 cm to 2 cm were considered. Monte Carlo (MC) simulations were performed to calculate energy-dependent dosimetric parameters and to study the DAPR 20,10 properties. Aspects relevant to DAPR 20,10 measurement were explored using large-area plane-parallel ionization chambers with different diameters. DAPR 20,10 was nearly independent of field size in line with the small differences among the corresponding mean beam energies. Both MC and experimental results showed a dependence of DAPR 20,10 on the measurement setup and the surface over which D w is integrated. For a given setup, DAPR 20,10 values obtained using ionization chambers with different air-cavity diameters agreed with one another within 0.4%, after the application of MC correction factors accounting for effects due to the chamber size. DAPR 20,10 differences among the small field sizes were within 1% and sensitivity to the beam energy resulted similar to that of established beam quality specifiers based on the point measurement of D w . For a specific measurement setup and integration area, DAPR 20,10 proved suitable to specify the beam quality of small photon beams for the selection of energy-dependent dosimetric parameters. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  11. The ESTRO-EQUAL quality assurance network for photon and electron radiotherapy beams in Germany

    International Nuclear Information System (INIS)

    Ferreira, I.H.; Dutreix, A.; Richter, J.; Bridier, A.; Chavaudra, J.; Svensson, H.

    2001-01-01

    Background: In 1998 an ESTRO Quality Assurance Network for radiotherapy (EQUAL) has been set up for 25 European countries for photon and electron beams in reference and non-reference conditions. Material and Methods: Measurements are done using LiF powder (DTL937-Philitech, France) that is processed with the PCL3 automatic reader (Fimel-PTW). The participating centers irradiate the TLDs with an absorbed dose of 2 Gy according to the clinical routine. Results: Until September 2000 EQUAL has checked 135 photon beams (including the beams rechecked) from 51 radiotherapy centers in Germany out of 86 accepted centers. The results show that 2% of the beam outputs in reference conditions and 3% of the percentage depth doses are outside the tolerance level (deviation > ± 5%). 6% of the beam output variations and of the wedge transmission factors show deviations > ± 5%. The global analysis of results shows deviations > ± 5% in at least one parameter for 18 beams out of the 135 beams checked. Five rechecked beams present one ''real dosimetric'' problem in one or more parameters, corresponding to 4% of the 114 beams for which the deviations cannot be attributed to set-up errors. - The EQUAL network has checked 89 electron beams in Germany. The results show that all beam outputs checked are within the tolerance level. The standard deviation for the beam output in reference conditions is 2.0% and 2.2% for the beam output for the others field sizes. The percentage of deviations > 3% and ≤ 5% for the reference beam output is higher for electron beams than for photon beam checks. Therefore the electron beam calibration and the TPS algorithms should be improved to increase the accuracy of the patient dosimetry for radiotherapy. (orig.) [de

  12. Beam propagation factor and Kurtosis parameter of different types of flattened Gaussian beams

    International Nuclear Information System (INIS)

    Saghafi, S.; Forbes, G.W.; Sheppard, C.J.R.

    1999-01-01

    Full text: The beam propagation factor, M 2 and the Kurtosis parameter, K, are considered for three different models of flattened Gaussian beams. Plots of M 2 versus K reveal similarities between these flattened beams. In fact, for this type of beam, it is possible to predict K from the value of M 2 We also determine the values of the parameters that characterize those different types of flattened Gaussian beam modes for any given value of M 2 . Finally, once K and M 2 have been measured for any flattened beam, these equations can be used to determine the closeness of this real beam to members of the three well-known classes of flattened beams. This can facilitate the analyses of the beam and its propagation. Copyright (1999) Australian Optical Society

  13. High beam quality and high energy short-pulse laser with MOPA

    Science.gov (United States)

    Jin, Quanwei; Pang, Yu; Jiang, JianFeng; Tan, Liang; Cui, Lingling; Wei, Bin; Sun, Yinhong; Tang, Chun

    2018-03-01

    A high energy, high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with two amplifier stages is demonstrated. The two-rod birefringence compensation was used as beam quality controlling methods, which presents a short-pulse energy of 40 mJ with a beam quality value of M2 = 1.2 at a repetition rate of 400Hz. The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns.The method of spherical aberration compensation is improved the beam quality, a M2 factor of 2.3 and an optical-to-optical efficiency of 27.7% is obtained at the maximum laser out power.The laser obtained 1.4J out energy with polarization integration.

  14. Factors influencing bone scan quality

    International Nuclear Information System (INIS)

    Adams, F.G.; Shirley, A.W.

    1983-01-01

    A reliable subjective method of assessing bone scan quality is described. A large number of variables which theoretically could influence scan quality were submitted to regression and factor analysis. Obesity, age, sex and abnormality of scan were found to be significant but weak variables. (orig.)

  15. Factors Influencing Healthcare Service Quality

    Directory of Open Access Journals (Sweden)

    Ali Mohammad Mosadeghrad

    2014-07-01

    Full Text Available Background The main purpose of this study was to identify factors that influence healthcare quality in the Iranian context. Methods Exploratory in-depth individual and focus group interviews were conducted with 222 healthcare stakeholders including healthcare providers, managers, policy-makers, and payers to identify factors affecting the quality of healthcare services provided in Iranian healthcare organisations. Results Quality in healthcare is a production of cooperation between the patient and the healthcare provider in a supportive environment. Personal factors of the provider and the patient, and factors pertaining to the healthcare organisation, healthcare system, and the broader environment affect healthcare service quality. Healthcare quality can be improved by supportive visionary leadership, proper planning, education and training, availability of resources, effective management of resources, employees and processes, and collaboration and cooperation among providers. Conclusion This article contributes to healthcare theory and practice by developing a conceptual framework that provides policy-makers and managers a practical understanding of factors that affect healthcare service quality.

  16. Quality factors for monoenergetic neutrons

    International Nuclear Information System (INIS)

    Cross, W.G.; Ing, H.

    1984-01-01

    Mean quality factors anti Q(E/sub n/), for the dose resulting from first interactons of monoenergetic neutrons in tissue, have been calculated at energies from thermal to 14.7 MeV. Knowledge of these values, along with kerma factors, allows the calculation of the heavy-particle dose equivalent for any known neutron spectrum in tissue. The partial quality factors for the dose delivered by C, N, and O elastic and inelastic recoils are found to be virtually independent of the scattering angular distributions and are given by simple expressions

  17. Evaluating the beam quality of double-cladding fiber lasers in applications.

    Science.gov (United States)

    Yan, Ping; Wang, Xuejiao; Gong, Mali; Xiao, Qirong

    2016-08-10

    We put forward a new βFL factor, which is used exclusively in fiber lasers and is suitable to assess beam quality and choose the LP01 mode as the new suitable ideal beam. We present a new simple measurement method and verify the reasonability of the βFL factor in experiment in a 20/400 μm fiber laser. Furthermore, we use the βFL factor to evaluate the beam quality of a 3-kW-level fiber laser. It can be concluded that βFL is a key factor not only for assessing the performance of the high-power fiber laser that is our main focus, but also for the simple measurement.

  18. Factors affecting dental service quality.

    Science.gov (United States)

    Bahadori, Mohammadkarim; Raadabadi, Mehdi; Ravangard, Ramin; Baldacchino, Donia

    2015-01-01

    Measuring dental clinic service quality is the first and most important factor in improving care. The quality provided plays an important role in patient satisfaction. The purpose of this paper is to identify factors affecting dental service quality from the patients' viewpoint. This cross-sectional, descriptive-analytical study was conducted in a dental clinic in Tehran between January and June 2014. A sample of 385 patients was selected from two work shifts using stratified sampling proportional to size and simple random sampling methods. The data were collected, a self-administered questionnaire designed for the purpose of the study, based on the Parasuraman and Zeithaml's model of service quality which consisted of two parts: the patients' demographic characteristics and a 30-item questionnaire to measure the five dimensions of the service quality. The collected data were analysed using SPSS 21.0 and Amos 18.0 through some descriptive statistics such as mean, standard deviation, as well as analytical methods, including confirmatory factor. Results showed that the correlation coefficients for all dimensions were higher than 0.5. In this model, assurance (regression weight=0.99) and tangibility (regression weight=0.86) had, respectively, the highest and lowest effects on dental service quality. The Parasuraman and Zeithaml's model is suitable to measure quality in dental services. The variables related to dental services quality have been made according to the model. This is a pioneering study that uses Parasuraman and Zeithaml's model and CFA in a dental setting. This study provides useful insights and guidance for dental service quality assurance.

  19. The SPS Beam quality monitor, from design to operation

    CERN Document Server

    Papotti, G; Follin, F; Shaposhnikova, E

    2011-01-01

    The SPS Beam Quality Monitor is a system that monitors longitudinal beam parameters on a cycle-by-cycle basis and prevents extraction to the LHC in case the specifications are not met. This avoids losses, unnecessary stress of machine protection components and luminosity degradation, additionally helping efficiency during the filling process. The system has been operational since the 2009 LHC run, checking the beam pattern, its correct position with respect to the LHC references, individual bunch lengths and stability. In this paper the algorithms used, the hardware implementation and the operational aspects are presented.

  20. Multi-institutional Prospective Evaluation of Bowel Quality of Life After Prostate External Beam Radiation Therapy Identifies Patient and Treatment Factors Associated With Patient-Reported Outcomes: The PROSTQA Experience

    Energy Technology Data Exchange (ETDEWEB)

    Hamstra, Daniel A., E-mail: dhamm@med.umich.edu [Department of Radiation Oncology, The University of Michigan Medical Center, Ann Arbor, Michigan (United States); Conlon, Anna S.C.; Daignault, Stephanie [Department of Biostatistics, The University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan (United States); Dunn, Rodney L. [Department of Urology, The University of Michigan Medical Center, Ann Arbor, Michigan (United States); Sandler, Howard M. [Department of Radiation Oncology, Cedars Sinai Medical Center, Los Angeles, California (United States); Hembroff, A. Larry [Office for Survey Research, Michigan State University, East Lansing, Michigan (United States); Zietman, Anthony L. [Department of Radiation Oncology, The Massachusetts General Hospital, Boston, Massachusetts (United States); Kaplan, Irving [Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts (United States); Ciezki, Jay [Department of Radiation Oncology, The Cleveland Clinic, Cleveland, Ohio (United States); Kuban, Deborah A. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Wei, John T. [Department of Urology, The University of Michigan Medical Center, Ann Arbor, Michigan (United States); Sanda, Martin G. [Department of Urology, Emory University Medical Center, Atlanta, Georgia (United States); Michalski, Jeff M. [Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri (United States)

    2013-07-01

    Purpose: To evaluate patients treated with external beam radiation therapy as part of the multicenter Prostate Cancer Outcomes and Satisfaction with Treatment Quality Assessment (PROSTQA), to identify factors associated with posttreatment patient-reported bowel health-related quality of life (HRQOL). Methods and Materials: Pretreatment characteristics and treatment details among 292 men were evaluated using a general linear mixed model for their association with measured HRQOL by the Expanded Prostate Cancer Index Composite instrument through 2 years after enrollment. Results: Bowel HRQOL had a median score of 100 (interquartile range 91.7-100) pretreatment and 95.8 (interquartile range 83.3-100) at 2 years, representing new moderate/big problems in 11% for urgency, 7% for frequency, 4% for bloody stools, and 8% for an overall bowel problems. Baseline bowel score was the strongest predictor for all 2-year endpoints. In multivariable models, a volume of rectum ≥25% treated to 70 Gy (V70) yielded a clinically significant 9.3-point lower bowel score (95% confidence interval [CI] 16.8-1.7, P=.015) and predicted increased risks for moderate to big fecal incontinence (P=.0008). No other radiation therapy treatment-related variables influenced moderate to big changes in rectal HRQOL. However, on multivariate analyses V70 ≥25% was associated with increases in small, moderate, or big problems with the following: incontinence (3.9-fold; 95% CI 1.1-13.4, P=.03), rectal bleeding (3.6-fold; 95% CI 1.3-10.2, P=.018), and bowel urgency (2.9-fold; 95% CI 1.1-7.6, P=.026). Aspirin use correlated with a clinically significant 4.7-point lower bowel summary score (95% CI 9.0-0.4, P=.03) and an increase in small, moderate, or big problems with bloody stools (2.8-fold; 95% CI 1.2-6.4, P=.018). Intensity modulated radiation therapy was associated with higher radiation therapy doses to the prostate and lower doses to the rectum but did not independently correlate with bowel HRQOL

  1. Multi-institutional Prospective Evaluation of Bowel Quality of Life After Prostate External Beam Radiation Therapy Identifies Patient and Treatment Factors Associated With Patient-Reported Outcomes: The PROSTQA Experience

    International Nuclear Information System (INIS)

    Hamstra, Daniel A.; Conlon, Anna S.C.; Daignault, Stephanie; Dunn, Rodney L.; Sandler, Howard M.; Hembroff, A. Larry; Zietman, Anthony L.; Kaplan, Irving; Ciezki, Jay; Kuban, Deborah A.; Wei, John T.; Sanda, Martin G.; Michalski, Jeff M.

    2013-01-01

    Purpose: To evaluate patients treated with external beam radiation therapy as part of the multicenter Prostate Cancer Outcomes and Satisfaction with Treatment Quality Assessment (PROSTQA), to identify factors associated with posttreatment patient-reported bowel health-related quality of life (HRQOL). Methods and Materials: Pretreatment characteristics and treatment details among 292 men were evaluated using a general linear mixed model for their association with measured HRQOL by the Expanded Prostate Cancer Index Composite instrument through 2 years after enrollment. Results: Bowel HRQOL had a median score of 100 (interquartile range 91.7-100) pretreatment and 95.8 (interquartile range 83.3-100) at 2 years, representing new moderate/big problems in 11% for urgency, 7% for frequency, 4% for bloody stools, and 8% for an overall bowel problems. Baseline bowel score was the strongest predictor for all 2-year endpoints. In multivariable models, a volume of rectum ≥25% treated to 70 Gy (V70) yielded a clinically significant 9.3-point lower bowel score (95% confidence interval [CI] 16.8-1.7, P=.015) and predicted increased risks for moderate to big fecal incontinence (P=.0008). No other radiation therapy treatment-related variables influenced moderate to big changes in rectal HRQOL. However, on multivariate analyses V70 ≥25% was associated with increases in small, moderate, or big problems with the following: incontinence (3.9-fold; 95% CI 1.1-13.4, P=.03), rectal bleeding (3.6-fold; 95% CI 1.3-10.2, P=.018), and bowel urgency (2.9-fold; 95% CI 1.1-7.6, P=.026). Aspirin use correlated with a clinically significant 4.7-point lower bowel summary score (95% CI 9.0-0.4, P=.03) and an increase in small, moderate, or big problems with bloody stools (2.8-fold; 95% CI 1.2-6.4, P=.018). Intensity modulated radiation therapy was associated with higher radiation therapy doses to the prostate and lower doses to the rectum but did not independently correlate with bowel HRQOL

  2. Radiation quality of beams of negative pions

    International Nuclear Information System (INIS)

    Dicello, J.F.; Brenner, D.J.

    1981-01-01

    As a negative pion stops in tissue, it attaches itself to an adjacent atom to form a mesonic atom. Subsequently, the wave function of the pion interacts with that of the nucleus and the pion is absorbed. Because the energy associated with the rest mass of the pion is greater than the separation energy of the nuclear particles, the nucleus disintegrates (pion star). In tissue, approximately 40 MeV goes into overcoming the binding energies; 20 MeV goes into kinetic energy of charged particles; 80 MeV goes into kinetic energy of neutrons. In cases where biological studies are performed with beams of negative pions, as much as 20% of the total absorbed dose in the treatment volume and about 50% of the high-LET dose (> 100 keV/μm) can result from neutrons. The degree of biological response and the variation of that response throughout the treatment volume can be altered by the neutron dose

  3. Environmental factors and semen quality

    DEFF Research Database (Denmark)

    Jurewicz, Joanna; Hanke, Wojciech; Radwan, Michal

    2009-01-01

    , trihalomethanes (THMs), mobile phones) on semen quality, by reviewing most recent published literature. MATERIALS AND METHODS: Epidemiological studies focusing on exposure to environmental factors and semen quality for the last ten years were identified by a search of the Pubmed, Medline, Ebsco, Agricola...... to sperm motility. In case of air pollution, studies suggest a link between ambient air pollutants and various semen characteristics. Additional research is needed to corroborate this association and to establish the causal agents. Results of few studies on subfertile men demonstrate associations between...... phthalate levels commonly experienced by the public and impaired sperm quality (impact on sperm concentration, morphology, motility), but the findings have not been corroborated in studies of men from the general population. Mobile phones might adversely affect the quality of semen by decreasing mostly...

  4. SU-F-J-205: Effect of Cone Beam Factor On Cone Beam CT Number Accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Yao, W; Hua, C; Farr, J; Brady, S; Merchant, T [St. Jude Children’s Research Hospital, Memphis, TN (United States)

    2016-06-15

    Purpose: To examine the suitability of a Catphan™ 700 phantom for image quality QA of a cone beam computed tomography (CBCT) system deployed for proton therapy. Methods: Catphan phantoms, particularly Catphan™ 504, are commonly used in image quality QA for CBCT. As a newer product, Catphan™ 700 offers more tissue equivalent inserts which may be useful for generating the electron density – CT number curve for CBCT based treatment planning. The sensitometry-and-geometry module used in Catphan™ 700 is located at the end of the phantom and after the resolution line pair module. In Catphan™ 504 the line pair module is located at the end of the phantom and after the sensitometry-and-geometry module. To investigate the effect of difference in location on CT number accuracy due to the cone beam factor, we scanned the Catphan™ 700 with the central plane of CBCT at the center of the phantom, line pair and sensitometry-andgeometry modules of the phantom, respectively. The protocol head and thorax scan modes were used. For each position, scans were repeated 4 times. Results: For the head scan mode, the standard deviation (SD) of the CT numbers of each insert under 4 repeated scans was up to 20 HU, 11 HU, and 11 HU, respectively, for the central plane of CBCT located at the center of the phantom, line pair, and sensitometry-and-geometry modules of the phantom. The mean of the SD was 9.9 HU, 5.7 HU, and 5.9 HU, respectively. For the thorax mode, the mean of the SD was 4.5 HU, 4.4 HU, and 4.4 HU, respectively. The assessment of image quality based on resolution and spatial linearity was not affected by imaging location changes. Conclusion: When the Catphan™ 700 was aligned to the center of imaging region, the CT number accuracy test may not meet expectations. We recommend reconfiguration of the modules.

  5. Longitudinal Beam measurements at the LHC: The LHC Beam Quality Monitor

    CERN Document Server

    Papotti, G; Follin, F; Wehrle, U

    2011-01-01

    The LHC Beam Quality Monitor is a system that measures individual bunch lengths and positions, similarly to the twin system SPS Beam Quality Monitor, from which it was derived. The pattern verification that the system provides is vital during the injection process to verify the correctness of the injected pattern, while the bunch length measurement is fed back to control the longitudinal emittance blow up performed during the energy ramp and provides a general indication of the health of the RF system. The algorithms used, the hardware implementation and the system integration in the LHC control infrastructure are presented in this paper, along with possible improvements.

  6. Methods for slow axis beam quality improvement of high power broad area diode lasers

    Science.gov (United States)

    An, Haiyan; Xiong, Yihan; Jiang, Ching-Long J.; Schmidt, Berthold; Treusch, Georg

    2014-03-01

    For high brightness direct diode laser systems, it is of fundamental importance to improve the slow axis beam quality of the incorporated laser diodes regardless what beam combining technology is applied. To further advance our products in terms of increased brightness at a high power level, we must optimize the slow axis beam quality despite the far field blooming at high current levels. The later is caused predominantly by the built-in index step in combination with the thermal lens effect. Most of the methods for beam quality improvements reported in publications sacrifice the device efficiency and reliable output power. In order to improve the beam quality as well as maintain the efficiency and reliable output power, we investigated methods of influencing local heat generation to reduce the thermal gradient across the slow axis direction, optimizing the built-in index step and discriminating high order modes. Based on our findings, we have combined different methods in our new device design. Subsequently, the beam parameter product (BPP) of a 10% fill factor bar has improved by approximately 30% at 7 W/emitter without efficiency penalty. This technology has enabled fiber coupled high brightness multi-kilowatt direct diode laser systems. In this paper, we will elaborate on the methods used as well as the results achieved.

  7. High quality electron beams from a laser wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, S M; Issac, R C; Welsh, G H; Brunetti, E; Shanks, R P; Anania, M P; Cipiccia, S; Manahan, G G; Aniculaesei, C; Ersfeld, B; Islam, M R; Burgess, R T L; Vieux, G; Jaroszynski, D A [SUPA, Department of Physics, University of Strathclyde, Glasgow (United Kingdom); Gillespie, W A [SUPA, Division of Electronic Engineering and Physics, University of Dundee, Dundee (United Kingdom); MacLeod, A M [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee (United Kingdom); Van der Geer, S B; De Loos, M J, E-mail: m.wiggins@phys.strath.ac.u [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2010-12-15

    High quality electron beams have been produced in a laser-plasma accelerator driven by femtosecond laser pulses with a peak power of 26 TW. Electrons are produced with an energy up to 150 MeV from the 2 mm gas jet accelerator and the measured rms relative energy spread is less than 1%. Shot-to-shot stability in the central energy is 3%. Pepper-pot measurements have shown that the normalized transverse emittance is {approx}1{pi} mm mrad while the beam charge is in the range 2-10 pC. The generation of high quality electron beams is understood from simulations accounting for beam loading of the wakefield accelerating structure. Experiments and self-consistent simulations indicate that the beam peak current is several kiloamperes. Efficient transportation of the beam through an undulator is simulated and progress is being made towards the realization of a compact, high peak brilliance free-electron laser operating in the vacuum ultraviolet and soft x-ray wavelength ranges.

  8. Emittance measuring unit for 100% duty factor linac injector beams

    Energy Technology Data Exchange (ETDEWEB)

    Shubaly, M R; Pachner, J Jr; Ormrod, J H; Ungrin, J; Schriber, S O [ed.

    1976-11-01

    A description is given of a system to measure the emittance of a 750 keV 100 mA dc proton beam suitable for injection into a 100% duty factor linear accelerator. A relatively slowly pulsed 45/sup 0/ magnet switches the beam to a beam dump inside the emittance measuring unit for approx. 10 s. A fast pulsed 5/sup 0/ magnet then deflects the beam to a multiple aperture ''pepper-pot'' plate for 300 ..mu..s. Beamlets passing through the plate travel 520 mm and produce a pattern on a scintillator screen. A photograph of the pattern is analyzed to determine beam emittance. Preliminary results on low current beams show a gross increase in the emittance in the horizontal plane.

  9. Image quality of cone beam CT on respiratory motion

    International Nuclear Information System (INIS)

    Zhang Ke; Li Minghui; Dai Jianrong; Wang Shi

    2011-01-01

    In this study,the influence of respiratory motion on Cone Beam CT (CBCT) image quality was investigated by a motion simulating platform, an image quality phantom, and a kV X-ray CBCT. A total of 21 motion states in the superior-inferior direction and the anterior-posterior direction, separately or together, was simulated by considering different respiration amplitudes, periods and hysteresis. The influence of motion on CBCT image quality was evaluated with the quality indexes of low contrast visibility, geometric accuracy, spatial resolution and uniformity of CT values. The results showed that the quality indexes were affected by the motion more prominently in AP direction than in SI direction, and the image quality was affected by the respiration amplitude more prominently than the respiration period and the hysteresis. The CBCT image quality and its characteristics influenced by the respiration motion, and may be exploited in finding solutions. (authors)

  10. Determination of the quality index (Q) for photon beams at arbitrary field sizes.

    Science.gov (United States)

    Sauer, Otto A

    2009-09-01

    A commonly used beam quality index (Q) for high-energy photon beams is the tissue phantom ratio (TPR20,10) for a square field of 10 x 10 cm2 and SDD of 100 cm. On some specialized radiotherapy treatment equipment such a reference collimator setting is not achievable. Likewise a flat beam profile, not explicitly required in dosimetry protocols, but certainly influences the measurement of Q, is not always produced. In this work, a method was developed in order to determine Q at any field size, especially for small and nonflattened beams. An analytical relationship was derived between TPR20,10 for arbitrary field sizes and Q [the TPR20,10 (10 x 10 cm2)] as quality index. The proposed model equation was fitted to the measured and published data in order to achieve three general fit parameters. The procedure was then tested with published data from TomoTherapy and CyperKnife treatment devices. For standard flattened photon fields, the uncertainty in Q measured at any field size using the parameters derived from this study is better than 1%. In flattening-filter free beams, the proposed procedure results in a reliable Q for any field size setting. A method is introduced and successfully tested in order to measure the beam quality under nonstandard conditions. It can be used, e.g., to get energy dependent correction factors as tabulated in dosimetry codes of practice even if standard conditions are not adjustable.

  11. Large deflection angle, high-power adaptive fiber optics collimator with preserved near-diffraction-limited beam quality.

    Science.gov (United States)

    Zhi, Dong; Ma, Yanxing; Chen, Zilun; Wang, Xiaolin; Zhou, Pu; Si, Lei

    2016-05-15

    We report on the development of a monolithic adaptive fiber optics collimator, with a large deflection angle and preserved near-diffraction-limited beam quality, that has been tested at a maximal output power at the 300 W level. Additionally, a new measurement method of beam quality (M2 factor) is developed. Experimental results show that the deflection angle of the collimated beam is in the range of 0-0.27 mrad in the X direction and 0-0.19 mrad in the Y direction. The effective working frequency of the device is about 710 Hz. By employing the new measurement method of the M2 factor, we calculate that the beam quality is Mx2=1.35 and My2=1.24, which is in agreement with the result from the beam propagation analyzer and is preserved well with the increasing output power.

  12. Present status of high quality beam facility at Waseda University

    International Nuclear Information System (INIS)

    Washio, M.; Kawai, H.; Hama, Y.; Kudo, N.; Kobayashi, M.; Kuribayasi, T.; Kawaguchi, M.; Kuroda, R.; Maeda, K.; Nagasawa, F.; Ueyama, D.; Hizume, K.; Wang, X.J.; Hayano, H.; Urakawa, J.; Kashiwagi, S.

    2004-01-01

    A research project named High-Tech Research Center Project has been conducted at Waseda University. In this project, an RF gun system has been used for production of low emittance and short bunched electron beam. The experiments for the electron beam quality measurement have been carried out by slit scan techniques, etc. Short pulsed x-ray with the energy range of so-called water window has been generation by the inverse compton scattering. Further, the pulse radiolysis system has been constructed, and the stroboscopic pulse radiolysis has been applied for the detection of hydrated electron in picosecond time region. (author)

  13. Commissioning of output factors for uniform scanning proton beams

    International Nuclear Information System (INIS)

    Zheng Yuanshui; Ramirez, Eric; Mascia, Anthony; Ding Xiaoning; Okoth, Benny; Zeidan, Omar; Hsi Wen; Harris, Ben; Schreuder, Andries N.; Keole, Sameer

    2011-01-01

    Purpose: Current commercial treatment planning systems are not able to accurately predict output factors and calculate monitor units for proton fields. Patient-specific field output factors are thus determined by either measurements or empirical modeling based on commissioning data. The objective of this study is to commission output factors for uniform scanning beams utilized at the ProCure proton therapy centers. Methods: Using water phantoms and a plane parallel ionization chamber, the authors first measured output factors with a fixed 10 cm diameter aperture as a function of proton range and modulation width for clinically available proton beams with ranges between 4 and 31.5 cm and modulation widths between 2 and 15 cm. The authors then measured the output factor as a function of collimated field size at various calibration depths for proton beams of various ranges and modulation widths. The authors further examined the dependence of the output factor on the scanning area (i.e., uncollimated proton field), snout position, and phantom material. An empirical model was developed to calculate the output factor for patient-specific fields and the model-predicted output factors were compared to measurements. Results: The output factor increased with proton range and field size, and decreased with modulation width. The scanning area and snout position have a small but non-negligible effect on the output factors. The predicted output factors based on the empirical modeling agreed within 2% of measurements for all prostate treatment fields and within 3% for 98.5% of all treatment fields. Conclusions: Comprehensive measurements at a large subset of available beam conditions are needed to commission output factors for proton therapy beams. The empirical modeling agrees well with the measured output factor data. This investigation indicates that it is possible to accurately predict output factors and thus eliminate or reduce time-consuming patient-specific output

  14. Fundamental factors influencing portal image quality

    International Nuclear Information System (INIS)

    Jaffray, D.A.

    1995-01-01

    It has been recognized that improved methods of verifying radiation field placement in external beam radiotherapy are required in order to make frequent checks of field placement feasible. As a result, a large number of electronic portal imaging systems have been developed as possible replacements for film. These developments have produced digital systems with faster acquisition and improved display contrast, however, the quality of the images acquired with such systems is still disappointing. This presentation examines many of the fundamental factors which limit the quality of radiographs obtained with a megavoltage radiotherapy beam. The size and shape of the radiation sources (focal and extra-focal) in radiotherapy machines and their influence on the spatial resolution of portal images are examined. Monte Carlo simulations of x-ray interactions within the patient determined that a significant fraction of the x-ray scatter generated in the patient is due to bremsstrahlung and positron annihilation. Depending on the detector, the scatter signal can reduce the differential signal-to-noise by 20%. Furthermore, a Monte Carlo study of the interaction of x-rays within typical fluoroscopic imaging detectors (metal plate/phosphor screen) demonstrates the degrading effect of energy absorption noise on the detective quantum efficiency of fluoroscopic based imaging systems. Finally, the spatial frequency content in the x-ray shadowgram is demonstrated to change with x-ray energy, resulting in images that appear to have reduced spatial resolution at megavoltage energies. The relative magnitude of each of these factors will be presented and recommendations for the next generation of portal imaging systems will be made

  15. A Review on Audit Quality Factors

    OpenAIRE

    Hosseinniakani, Seyed; Inácio, Coelho Helena; Mota, Rui

    2014-01-01

    “Audit Quality” is not easy to define because of many diverse factors affecting quality. According to the consultation paper of the International Auditing and Assurance Standards Board (IAASB), audit quality is the significant issue that requires more considerable attention. Understanding how audit quality is important requires investigating audit quality factors more precisely. So, the present article aims to review and summarize the different audit quality factors, comparing the results ach...

  16. Postharvest quality of cut roses following electron-beam irradiation

    International Nuclear Information System (INIS)

    Chang, A.Y.; Gladon, R.J.; Gleason, M.L.; Parker, S.K.; Agnew, N.H.; Olson, D.G.

    1997-01-01

    Cut Rosa x hybrida L. 'Royalty' flowers were used to determine the efficacy of electron-beam irradiation for increasing postharvest quality and decreasing petal infection by Botrytis cinerea Pers. In an experiment for determining the injury threshold, roses received electron-beam irradiation of 0, 0.5, 1, 2, and 4 kGy. Irradiation dosages greater than or equal to 4 kGy caused necrosis on petal tissue and decreased postharvest life at 20 degrees C. In a second experiment to evaluate postharvest quality, roses were irradiated at 0, 0.25, 0.5, 0.75, and 1 kGy. Dosages of 0.25 and 0.5 kGy slowed the rate of flower bud opening for 2 days but did not decrease postharvest quality when compared with nonirradiated roses. Roses that received irradiation dosages of 0.75 and 1 kGy showed unacceptable quality. In a third experiment, roses that had or had not been inoculated with B. cinerea were irradiated at 0, 0.25, 0.5, and 0.75 kGy. Irradiation did not control B. cinerea populations, and rose quality decreased as dosage increased. In a fourth experiment to determine the effect of irradiation on B. cinerea, conidia on water-agar plates exposed to dosages less than or equal to 1, 2, and 4 kGy germinated at rates of approximately 90%, 33%, and 2%, respectively, within 24 h

  17. Stress Concentration Factor and Stress Intensity Factor with U-notch and Crack in the Beam

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Bo Seong; Lee, Kwang Ho [Kyungpook National Univ., Daegu (Korea, Republic of)

    2016-05-15

    The stress concentration factors and stress intensity factors for a simple beam and a cantilever are analyzed by using finite element method and photoelasticity. Using the analyzed results, the estimated graphs on stress concentration factors and stress intensity factors are obtained. To analyze stress concentration factors of notch, the dimensionless notch length H(height of specimen)/h=1.1-2 and dimensionless gap space r(radius at the notch tip)/h=0.1~0.5 are used, where h=H-c and c is the notch length. As the notch gap length increases and the gap decreases, the stress concentration factors increase. Stress concentration factors of a simple beam are greater than those of a cantilever beam. However, actually, the maximum stress values under a load, a notch length and a gap occur more greatly in the cantilever beam than in the simple beam. To analyze stress intensity factors, the normalized crack length α(crack length)/H=0.2~0.5 is used. As the length of the crack increases, the normalized stress intensity factors increase. The stress intensity factors under a constant load and a crack length occur more greatly in the cantilever beam than in the simple beam.

  18. Comparison of photon beam qualities for treatment of deep seated tumours

    International Nuclear Information System (INIS)

    Ssengabi, J.

    1977-06-01

    Physical parameters that influence the quality of photon beams have been examined. The interaction of photon beams of different qualities from cobolt-60 gamma rays to 42 MV X-rays, with a patient-target region system has been investigated with a view to compare the photon beam qualities under specified irradiation conditions. The concept of integral dose and its use in photon beam intercomparison has been investigated. The results of the study have shown the inadequacy of a single beam parameter, such as the central axis depth dose data, in the intercomparison of photon beam qualities for the treatment of deep seated tumours. (author)

  19. X-ray beam qualities for dental radiology purposes

    International Nuclear Information System (INIS)

    Santos, Marcus Aurelio P. dos; Fragoso, Maria da Conceicao de F.; Lima, Ricardo de A.; Hazim, Clovis A.

    2009-01-01

    In order to establish characteristics or properties of equipment for diagnostic radiology, e.g. ion chambers and semiconductor detectors, calibration laboratories offer a set of well-defined radiation conditions, called X-ray qualities, which can be used for many Physics studies and medical purposes. The standardization of radiation qualities has been carried out in several fields of study, but little attention has been given to the area of dental radiology, mainly for medical and physical applications using single-phase units with half-wave rectification. For this reason, a single-phase dental unit with adjustable peak voltage and tube current, called 'variable potential X-ray equipment', was developed aiming to define X-ray beam qualities for test and calibrations purposes. X-ray spectra at 50, 60 and 70 kVp were determined by using a CdTe detector and compared with those obtained for ten commercial X-ray dental units. As a result of this study, a set of X-ray qualities for the variable potential X-ray equipment was determined. The X-ray qualities spectra were utilized as reference for determination of a new set of X-ray qualities characterized for a constant potential X-ray equipment. Thus, sets of X-ray qualities were standardized and implemented in two X-ray laboratories: one with the variable potential X-ray equipment and other with constant potential X-ray equipment. These reference X-ray beam qualities should be used for test and calibration purposes involving scientific studies and services. (author)

  20. Analytically derived weighting factors for transmission tomography cone beam projections

    International Nuclear Information System (INIS)

    Yao Weiguang; Leszczynski, Konrad

    2009-01-01

    Weighting factors, which define the contributions of individual voxels of a 3D object to individual projection elements (pixels) on the detector, are the basic elements required in iterative tomographic reconstructions from transmission projections. Exact or as accurate as possible values for weighting factors are required in high-resolution reconstructions. Geometric complexity of the problem, however, makes it difficult to obtain exact weighting factor values. In this work, we derive an analytical expression for the weighting factors in cone beam projection geometry. The resulting formula is validated and applied to reconstruction from mega and kilovoltage x-ray cone beam projections. The reconstruction speed and accuracy are significantly improved by using the weighting factor values.

  1. ISTC projects devoted to improving laser beam quality

    Science.gov (United States)

    Malakhov, Yu. I.

    2007-05-01

    Short overview is done about the activity of ISTC in a direction concerned with improving powerful laser beam quality by means of nonlinear and linear adaptive optics methods. Completed projects #0591 and #1929 resulted in the development of a stimulated Brillouin scattering (SBS) phase conjugation mirror of superhigh fidelity employing the kinoform optical elements (rasters of small lenses) of new generation designed for pulsed or pulse-periodic lasers with nanosecond scale pulse duration. Project #2631 is devoted to development of an adaptive optical system for phase registration and correction of laser beams with wave front vortices. The principles of operation of conventional adaptive systems are based on the assumption that the phase is a smooth continuous function in space. Therefore the solution of the Project tasks will assume a new step in adaptive optics.

  2. Image simulation and a model of noise power spectra across a range of mammographic beam qualities

    Energy Technology Data Exchange (ETDEWEB)

    Mackenzie, Alistair, E-mail: alistairmackenzie@nhs.net; Dance, David R.; Young, Kenneth C. [National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Diaz, Oliver [Centre for Vision, Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom and Computer Vision and Robotics Research Institute, University of Girona, Girona 17071 (Spain)

    2014-12-15

    Purpose: The aim of this work is to create a model to predict the noise power spectra (NPS) for a range of mammographic radiographic factors. The noise model was necessary to degrade images acquired on one system to match the image quality of different systems for a range of beam qualities. Methods: Five detectors and x-ray systems [Hologic Selenia (ASEh), Carestream computed radiography CR900 (CRc), GE Essential (CSI), Carestream NIP (NIPc), and Siemens Inspiration (ASEs)] were characterized for this study. The signal transfer property was measured as the pixel value against absorbed energy per unit area (E) at a reference beam quality of 28 kV, Mo/Mo or 29 kV, W/Rh with 45 mm polymethyl methacrylate (PMMA) at the tube head. The contributions of the three noise sources (electronic, quantum, and structure) to the NPS were calculated by fitting a quadratic at each spatial frequency of the NPS against E. A quantum noise correction factor which was dependent on beam quality was quantified using a set of images acquired over a range of radiographic factors with different thicknesses of PMMA. The noise model was tested for images acquired at 26 kV, Mo/Mo with 20 mm PMMA and 34 kV, Mo/Rh with 70 mm PMMA for three detectors (ASEh, CRc, and CSI) over a range of exposures. The NPS were modeled with and without the noise correction factor and compared with the measured NPS. A previous method for adapting an image to appear as if acquired on a different system was modified to allow the reference beam quality to be different from the beam quality of the image. The method was validated by adapting the ASEh flat field images with two thicknesses of PMMA (20 and 70 mm) to appear with the imaging characteristics of the CSI and CRc systems. Results: The quantum noise correction factor rises with higher beam qualities, except for CR systems at high spatial frequencies, where a flat response was found against mean photon energy. This is due to the dominance of secondary quantum noise

  3. Using a tandem ionization chamber for quality control of X-ray beams

    International Nuclear Information System (INIS)

    Yoshizumi, Maira T.; Caldas, Linda V.E.

    2011-01-01

    X-ray beam qualities are defined by both the mean energies and by the half-value layers (HVL). Many international protocols use the half-value layer and the beam voltage to characterize the X-ray beam quality. A quality control program for X-ray equipment includes the constancy check of beam qualities, i.e., the periodical verification of the half-value layer, which can be a time consumable procedure. A tandem ionization chamber, developed at Instituto de Pesquisas Energeticas e Nucleares, was used to determine the HVL and its constancy for five radiotherapy standard beam qualities. This ionization chamber is composed by two sensitive volumes with inner electrodes made of different materials: aluminum and graphite. The beam quality constancy check test was performed during two months and the maximum variation obtained was 1.24% for the radiation beam quality T-10. This result is very satisfactory according to national recommendations. (author)

  4. The quality of high-energy X-ray beams

    International Nuclear Information System (INIS)

    LaRiviere, P.D.

    1989-01-01

    Supplement 17 of the British Journal of Radiology is a survey of central-axis depth doses for radiotherapy machines, patterned largely on BJR Supplement 11 (1972). Inspection of high-energy X-ray depth doses for a 10 x 10 cm field at an SSD of 100 cm disclosed large differences between the two sets of data, especially for qualities above 8 MV, e.g. a depth dose of 80% at 10 cm is rated at about 19 MV according to BJR Supplement 11, and 23 MV according to BJR Supplement 17. It was found that Supplement 17 depth-dose data above 8 MV were erratic, but Supplement 11 data could be represented by an analytical expression, providing a unique means of assigning MV quality. It was also found that dose-weighted average energy of the filtered beam plotted smoothly against depth dose. For dosimetric purposes, it is suggested that this parameter be used as a true measure of beam quality, removing discrepancies introduced by the use of nominal MV for this purpose. (author)

  5. A quality audit program for external beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, W.F.; Stovall, M. [Univ. of Texas, Houston, TX (United States)

    1993-12-31

    For more than 25 years, the University of Texas M. D. Anderson Cancer Center has had a quality audit program using mailed dosimeters to verify radiation therapy machine output. Two programs, one compulsory and one voluntary, presently monitor therapy beams at more than 1000 megavoltage-therapy facilities. A successful program requires two major components: a high-precision thermoluminescent dosimeter (TLD) system and dedicated staff that interact closely with the users to resolve discrepancies. The TLD system, the logistics used, and the human interaction of these programs are described. Examples show that the programs can identify major discrepancies, exceeding 5 %, as well as discrepancies as small as 3%.

  6. A new method for improving beam quality of LINAC

    International Nuclear Information System (INIS)

    Xie Jialin; Li Fengtian; Wang Yanshan; Wang Bosi

    1999-01-01

    The principle of the self-adaptive feed-forward (SAFF) control to improve the beam quality of linac is introduced. the analytical procedure for calculating the control signals, the structure of a practical control system, and applications of SAFF in klystron, RF gun, and linac are presented, especially the application in the thermionic gun whose response is non-linear, time-variant and of large time-delay. The described control system is operational and some primary experimental results have been obtained, including the control of amplitude and phase fluctuations of the klystron output, the microwave field in the gun cavity and linac

  7. A quality audit program for external beam radiotherapy

    International Nuclear Information System (INIS)

    Hanson, W.F.; Stovall, M.

    1993-01-01

    For more than 25 years, the University of Texas M. D. Anderson Cancer Center has had a quality audit program using mailed dosimeters to verify radiation therapy machine output. Two programs, one compulsory and one voluntary, presently monitor therapy beams at more than 1000 megavoltage-therapy facilities. A successful program requires two major components: a high-precision thermoluminescent dosimeter (TLD) system and dedicated staff that interact closely with the users to resolve discrepancies. The TLD system, the logistics used, and the human interaction of these programs are described. Examples show that the programs can identify major discrepancies, exceeding 5 %, as well as discrepancies as small as 3%

  8. An electron beam imaging system for quality assurance in IORT

    Science.gov (United States)

    Casali, F.; Rossi, M.; Morigi, M. P.; Brancaccio, R.; Paltrinieri, E.; Bettuzzi, M.; Romani, D.; Ciocca, M.; Tosi, G.; Ronsivalle, C.; Vignati, M.

    2004-01-01

    Intraoperative radiation therapy is a special radiotherapy technique, which enables a high dose of radiation to be given in a single fraction during oncological surgery. The major stumbling block to the large-scale application of the technique is the transfer of the patient, with an open wound, from the operating room to the radiation therapy bunker, with the consequent organisational problems and the increased risk of infection. To overcome these limitations, in the last few years a new kind of linear accelerator, the Novac 7, conceived for direct use in the surgical room, has become available. Novac 7 can deliver electron beams of different energies (3, 5, 7 and 9 MeV), with a high dose rate (up to 20 Gy/min). The aim of this work, funded by ENEA in the framework of a research contract, is the development of an innovative system for on-line measurements of 2D dose distributions and electron beam characterisation, before radiotherapy treatment with Novac 7. The system is made up of the following components: (a) an electron-light converter; (b) a 14 bit cooled CCD camera; (c) a personal computer with an ad hoc written software for image acquisition and processing. The performances of the prototype have been characterised experimentally with different electron-light converters. Several tests have concerned the assessment of the detector response as a function of impulse number and electron beam energy. Finally, the experimental results concerning beam profiles have been compared with data acquired with other dosimetric techniques. The achieved results make it possible to say that the developed system is suitable for fast quality assurance measurements and verification of 2D dose distributions.

  9. The effect of thermal de-phasing on the beam quality of a high-power single-pass second harmonic generation

    Science.gov (United States)

    Sadat Hashemi, Somayeh; Ghavami Sabouri, Saeed; Khorsandi, Alireza

    2018-04-01

    We present a theoretical model in order to study the effect of a thermally loaded crystal on the quality of a second-harmonic (SH) beam generated in a high-power pumping regime. The model is provided based on using a particular structure of oven considered for MgO:PPsLT nonlinear crystal to compensate for the thermal de-phasing effect that as the pumping power reaches up to 50 W degrades the conversion efficiency and beam quality of the interacting beams. Hereupon, the quality of fundamental beam is involved in the modeling to investigate the final effect on the beam quality of generated SH beam. Beam quality evaluation is subsequently simulated using Hermite-Gaussian modal decomposition approach for a range of fundamental beam qualities varied from 1 to 3 and for different levels of input powers. To provide a meaningful comparison numerical simulation is correlated with real data deduced from a high-power SH generation (SHG) experimental device. It is found that when using the open-top oven scheme and fixing the fundamental M 2-factor at nearly 1, for a range of input powers changing from 15 to 30 W, the M 2-factor of SHG beam is degraded from 9% to 24%, respectively, confirming very good consistency with the reported experimental results.

  10. Morphometric analysis - Cone beam computed tomography to predict bone quality and quantity.

    Science.gov (United States)

    Hohlweg-Majert, B; Metzger, M C; Kummer, T; Schulze, D

    2011-07-01

    Modified quantitative computed tomography is a method used to predict bone quality and quantify the bone mass of the jaw. The aim of this study was to determine whether bone quantity or quality was detected by cone beam computed tomography (CBCT) combined with image analysis. MATERIALS AND PROCEDURES: Different measurements recorded on two phantoms (Siemens phantom, Comac phantom) were evaluated on images taken with the Somatom VolumeZoom (Siemens Medical Solutions, Erlangen, Germany) and the NewTom 9000 (NIM s.r.l., Verona, Italy) in order to calculate a calibration curve. The spatial relationships of six sample cylinders and the repositioning from four pig skull halves relative to adjacent defined anatomical structures were assessed by means of three-dimensional visualization software. The calibration curves for computer tomography (CT) and cone beam computer tomography (CBCT) using the Siemens phantom showed linear correlation in both modalities between the Hounsfield Units (HU) and bone morphology. A correction factor for CBCT was calculated. Exact information about the micromorphology of the bone cylinders was only available using of micro computer tomography. Cone-beam computer tomography is a suitable choice for analysing bone mass, but, it does not give any information about bone quality. 2010 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  11. Megavoltage planar and cone-beam imaging with low-Z targets: dependence of image quality improvement on beam energy and patient separation.

    Science.gov (United States)

    Robar, James L; Connell, Tanner; Huang, Weihong; Kelly, Robin G

    2009-09-01

    The purpose of this study is to investigate the improvement of megavoltage planar and cone-beam CT (CBCT) image quality with the use of low atomic number (Z) external targets in the linear accelerator. In this investigation, two experimental megavoltage imaging beams were generated by using either 3.5 or 7.0 MeV electrons incident on aluminum targets installed above the level of the carousel in a linear accelerator (2100EX, Varian Medical, Inc., Palo Alto, CA). Images were acquired using an amorphous silicon detector panel. Contrast-to-noise ratio (CNR) in planar and CBCT images was measured as a function of dose and a comparison was made between the imaging beams and the standard 6 MV therapy beam. Phantoms of variable diameter were used to examine the loss of contrast due to beam hardening. Porcine imaging was conducted to examine qualitatively the advantages of the low-Z target approach in CBCT. In CBCT imaging CNR increases by factors as high as 2.4 and 4.3 for the 7.0 and 3.5 MeV/Al beams, respectively, compared to images acquired with 6 MV. Similar factors of improvement are observed in planar imaging. For the imaging beams, beam hardening causes a significant loss of the contrast advantage with increasing phantom diameter; however, for the 3.5 MeV/Al beam and a phantom diameter of 25 cm, a contrast advantage remains, with increases of contrast by factors of 1.5 and 3.4 over 6 MV for bone and lung inhale regions, respectively. The spatial resolution is improved slightly in CBCT images for the imaging beams. CBCT images of a porcine cranium demonstrate qualitatively the advantages of the low-Z target approach, showing greater contrast between tissues and improved visibility of fine detail. The use of low-Z external targets in the linear accelerator improves megavoltage planar and CBCT image quality significantly. CNR may be increased by a factor of 4 or greater. Improvement of the spatial resolution is also apparent.

  12. Factors influencing equipment selection in electron beam processing

    Science.gov (United States)

    Barnard, J. W.

    2003-08-01

    During the eighties and nineties accelerator manufacturers dramatically increased the beam power available for high-energy equipment. This effort was directed primarily at meeting the demands of the sterilization industry. During this era, the perception that bigger (higher power, higher energy) was always better prevailed since the operating and capital costs of accelerators did not increase with power and energy as fast as the throughput. High power was needed to maintain per unit costs low for treatment. This philosophy runs counter to certain present-day realities of the sterilization business as well as conditions influencing accelerator selection in other electron beam applications. Recent experience in machine selection is described and factors affecting choice are presented.

  13. Determination of quality factors by microdosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Al-Affan, I.A.M.; Watt, D.E.

    1987-03-15

    The application of microdose parameters for the specification of a revised scale of quality factors which would be applicable at low doses and dose rates is examined in terms of an original proposal by Rossi. Two important modifications are suggested to enable an absolute scale of quality factors to be constructed. Allowance should be made to allow for the dependence of the saturation threshold of lineal energy on the type of heavy charged particle. Also, an artificial saturation threshold should be introduced for electron tracks as a means of modifying the measurements made in the microdosimeter to the more realistic site sizes of nanometer dimensions. The proposed absolute scale of quality factors nicely encompasses the high RBEs of around 3 observed at low doses for tritium ..beta.. rays and is consistent with the recent recommendation of the ICRP that the quality factor for fast neutrons be increased by a factor of two, assuming that there is no biological repair for the reference radiation.

  14. LD-pumped erbium and neodymium lasers with high energy and output beam quality

    Science.gov (United States)

    Kabanov, Vladimir V.; Bezyazychnaya, Tatiana V.; Bogdanovich, Maxim V.; Grigor'ev, Alexandr V.; Lebiadok, Yahor V.; Lepchenkov, Kirill V.; Ryabtsev, Andrew G.; Ryabtsev, Gennadii I.; Shchemelev, Maxim A.

    2013-05-01

    Physical and fabrication peculiarities which provide the high output energy and beam quality for the diode pumped erbium glass and Nd:YAG lasers are considered. Developed design approach allow to make passively Q-switched erbium glass eye-safe portable laser sources with output energy 8 - 12 mJ (output pulse duration is less than 25 ns, pulse repetition rate up to 5 Hz) and beam quality M2 less than 1.3. To reach these values the erbium laser pump unit parameters were optimized also. Namely, for the powerful laser diode arrays the optimal near-field fill-factor, output mirror reflectivity and heterostructure properties were determined. Construction of advanced diode and solid-state lasers as well as the optical properties of the active element and the pump unit make possible the lasing within a rather wide temperature interval (e.g. from minus forty till plus sixty Celsius degree) without application of water-based chillers. The transversally pumped Nd:YAG laser output beam uniformity was investigated depending on the active element (AE) pump conditions. In particular, to enhance the pump uniformity within AE volume, a special layer which practically doesn't absorb the pump radiation but effectively scatters the pump and lasing beams, was used. Application of such layer results in amplified spontaneous emission suppression and improvement of the laser output beam uniformity. The carried out investigations allow us to fabricate the solid-state Nd:YAG lasers (1064 nm) with the output energy up to 420 mJ at the pulse repetition rate up to 30 Hz and the output energy up to 100 mJ at the pulse repetition rate of of 100 Hz. Also the laser sources with following characteristics: 35 mJ, 30 Hz (266 nm); 60 mJ, 30 Hz (355 nm); 100 mJ, 30 Hz (532 nm) were manufactured on the base of the developed Nd:YAG quantrons.

  15. Tailoring the laser pulse shape to improve the quality of the self-injected electron beam in laser wakefield acceleration

    International Nuclear Information System (INIS)

    Upadhyay, Ajay K.; Samant, Sushil A.; Krishnagopal, S.

    2013-01-01

    In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement in the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.

  16. Quality factors to consider in condensate selection

    Energy Technology Data Exchange (ETDEWEB)

    Lywood, B. [Crude Quality Inc., Edmonton, AB (Canada)

    2009-07-01

    Many factors must be considered when assessing the feasibility of using condensates as a diluent for bitumen or heavy crude production blending. In addition to commercial issues, the effect of condensate quality is a key consideration. In general, condensate quality refers to density and viscosity. However, valuation decisions could be enhanced through the expansion of quality definitions and understanding. This presentation focused on the parameters that are important in choosing a diluent grade product. It also reviewed pipeline and industry specifications and provided additional information regarding general properties for bitumen and condensate compatibility; sampling and quality testing needs; and existing sources of information regarding condensate quality. tabs., figs.

  17. Improvement of the beam quality of a broad-area diode laser using double feedback from two external mirrors

    DEFF Research Database (Denmark)

    Chi, M.; Bøgh, A.-S.; Thestrup, B.

    2004-01-01

    In this letter, a symmetric double-feedback configuration, to improve the beam quality of broad-area diode lasers is demonstrated. With this configuration, a symmetric double-lobed far field can be obtained, and this configuration leads to good beam quality. The beam quality factor M-2 of a diode...... laser with the emitting area 1 mumx200 mum is improved by using both the asymmetric single feedback and the symmetric double feedback. M-2 values of 4.3 for the asymmetric single-feedback laser system and 3.3 for the symmetric double-feedback laser system are obtained, whereas the M-2 value...... of the freely running laser is 42. The far and the near fields are also measured and compared for the three conditions. (C) 2004 American Institute of Physics....

  18. Electron beam irradiation: a novel technology to enhance the quality of soybean seeds

    International Nuclear Information System (INIS)

    Bhalla, Shashi; Srinivasan, K.; Singh, Subadas; Thakur, Manju; Sharma, S.K.; Pramod, R.; Dwivedi, J.; Bapna, S.C.

    2010-01-01

    Soybean seeds, rich in protein and oil, maintain their germinability only for short durations under ambient conditions. Loss of viability of stored seeds often hampers soybean production in harsh environments worldwide. Physiological factors favored by high temperature and high moisture content accelerate the seed deterioration in the tropics. Several chemical and physical treatments are being used to enhance quality. Irradiation is a novel technology for food preservation and is gaining importance all over the world. Low doses of irradiation bring about improvement in quality of food/seeds, which can be beneficial in several ways. Electron Beam (EB) irradiation is a new approach in this area. The objective of present study was to investigate the effect of EB irradiation in enhancing the quality of low vigour soybean seeds

  19. Application of the entropy concept to describe the quality of a X-ray beam

    International Nuclear Information System (INIS)

    Oliveira, A.D.

    2002-01-01

    In a previous work (Oliveira and Pedroso de Lima, 2000), we introduced the concept of entropy to describe the degradation of the energy of a photon beam incident in a material. We pointed out the relation between both, the entropy of the distribution of the energy deposited in matter and the traditional quality factor of the radiation protection. From the point of view of the entropy, we showed that, in what concerns to the monoenergetic approximation to a polyenergetic beam, we can hardly speak in an approximation (Oliveira 2001). In fact, the behaviour of the entropy is very different for both, an X-ray and a monoenergetic beam. In this work we developed further the study of the degradation of the energy of X-ray photons, from the point of view of the entropy, introducing the concepts of surface entropy, S surf , equilibrium entropy, S eq , and concepts of entropy variation, namely, primary to surface variation, S ps , and total entropy variation, S T . These are characteristic parameters of the X-ray beams describing the degradation of the primary photons while they interact with matter

  20. Implementation to spanish protocol of quality control of accelerators to daily control of electron beams

    International Nuclear Information System (INIS)

    Adaimi Hernandez, P.; Ramirez Ros, J. C.; Casa de Julian, M. A. de la; Clemente Gutierrez, F.; Cabello Murillo, E.; Diaz Fuente, R.; Ferrando Sanchez, A.

    2011-01-01

    A revised procedure for daily control of the electron beams to make measurements more meaningful physically, having a better reproducibility and more in line with the recommendations of the Spanish Protocol for Quality Control in Electron Linear Accelerators Clinical Use. The daily quality control beams of high energy electrons that had been done so far was the finding that the record of a series of measures (symmetry, uniformity, stability, energy, beam central dose) were within tolerance values established. The amendment is to check the beam quality by directly measuring changes in absorption depth at which the dose is reduced to half its maximum value, R50.

  1. Analysis of ion beam teletherapy patient-specific quality assurance.

    Science.gov (United States)

    Liu, Xiaoli; Deng, Yu; Schlegel, Nicki; Huang, Zhijie; Moyers, Michael F

    2018-02-27

    The objective of this study was to evaluate the procedures for patient-specific quality assurance measurements using modulated scanned and energy stacked beams for proton and carbon ion teletherapy. Delivery records from 1734 portal measurements were analyzed using a 3-point pass criteria: more than 22 of 24 chambers in a water phantom (WP) had to have a measured dose difference from the planned portal doses less than or equal to 3%, or the distance from the measurement point location to a point location in the plan having the same dose had to be less than or equal to 3 mm (distance to agreement [DTA]), and the mean dose deviation of all chambers had to be less than 3%. Stratification of results showed some associations between measurement parameters and pass rates. For proton portals, pass rates were high at all measurement depths, but for carbon ion portals, pass rates decreased as a function of increasing measurement depth. Pass rates of both proton and carbon ion portals with 1 WP were slightly lower than those with a second WP. The total pass rates were 97.7% and 91.9% for proton and carbon ion patient portals, respectively. In general, the measured doses exhibited good agreement with the treatment planning system (TPS) calculated doses. When the chamber position was deeper than 150 mm in carbon ion beams, a lower pass rate was observed, which may have been caused by ion chamber array setup uncertainty (lateral and depth) in highly modulated portals or incorrect modeling of scatter by the TPS. These deviations need further investigation. Copyright © 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  2. Definition of parameters for quality assurance of flattening filter free (FFF) photon beams in radiation therapy

    International Nuclear Information System (INIS)

    Fogliata, A.; Garcia, R.; Knöös, T.; Nicolini, G.; Clivio, A.; Vanetti, E.; Khamphan, C.; Cozzi, L.

    2012-01-01

    Purpose: Flattening filter free (FFF) beams generated by medical linear accelerators have recently started to be used in radiotherapy clinical practice. Such beams present fundamental differences with respect to the standard filter flattened (FF) beams, making the generally used dosimetric parameters and definitions not always viable. The present study will propose possible definitions and suggestions for some dosimetric parameters for use in quality assurance of FFF beams generated by medical linacs in radiotherapy. Methods: The main characteristics of the photon beams have been analyzed using specific data generated by a Varian TrueBeam linac having both FFF and FF beams of 6 and 10 MV energy, respectively. Results: Definitions for dose profile parameters are suggested starting from the renormalization of the FFF with respect to the corresponding FF beam. From this point the flatness concept has been translated into one of “unflatness” and other definitions have been proposed, maintaining a strict parallelism between FFF and FF parameter concepts. Conclusions: Ideas for quality controls used in establishing a quality assurance program when introducing FFF beams into the clinical environment are given here, keeping them similar to those used for standard FF beams. By following the suggestions in this report, the authors foresee that the introduction of FFF beams into a clinical radiotherapy environment will be as safe and well controlled as standard beam modalities using the existing guidelines.

  3. Photoinjector beam quality improvement by shaping the wavefront of a drive laser with oblique incidence

    International Nuclear Information System (INIS)

    He Zhigang; Wang Xiaohui; Jia Qika

    2012-01-01

    To increase the quantum efficiency (QE) of a copper photocathode and reduce the thermal emittance of an electron beam, a drive laser with oblique incidence was adopted in a BNL type photocathode rf gun. The disadvantageous effects on the beam quality caused by oblique incidence were analyzed qualitatively. A simple way to solve the problems through wavefront shaping was introduced and the beam quality was improved. (authors)

  4. High quality-factor optical resonators

    International Nuclear Information System (INIS)

    Henriet, Rémi; Salzenstein, Patrice; Coillet, Aurélien; Saleh, Khaldoun; Chembo, Yanne K; Ristic, Davor; Ferrari, Maurizio; Mortier, Michel; Rasoloniaina, Alphonse; Dumeige, Yannick; Féron, Patrice; Cibiel, Gilles; Llopis, Olivier

    2014-01-01

    Various resonators are investigated for microwave photonic applications. Micro-sphere, disk and fiber ring resonators were designed, realized and characterized. Obtained quality factors are as high as Q = 10 10 . (paper)

  5. Monte Carlo-based investigations on the impact of removing the flattening filter on beam quality specifiers for photon beam dosimetry.

    Science.gov (United States)

    Czarnecki, Damian; Poppe, Björn; Zink, Klemens

    2017-06-01

    The impact of removing the flattening filter in clinical electron accelerators on the relationship between dosimetric quantities such as beam quality specifiers and the mean photon and electron energies of the photon radiation field was investigated by Monte Carlo simulations. The purpose of this work was to determine the uncertainties when using the well-known beam quality specifiers or energy-based beam specifiers as predictors of dosimetric photon field properties when removing the flattening filter. Monte Carlo simulations applying eight different linear accelerator head models with and without flattening filter were performed in order to generate realistic radiation sources and calculate field properties such as restricted mass collision stopping power ratios (L¯/ρ)airwater, mean photon and secondary electron energies. To study the impact of removing the flattening filter on the beam quality correction factors k Q , this factor for detailed ionization chamber models was calculated by Monte Carlo simulations. Stopping power ratios (L¯/ρ)airwater and k Q values for different ionization chambers as a function of TPR1020 and %dd(10) x were calculated. Moreover, mean photon energies in air and at the point of measurement in water as well as mean secondary electron energies at the point of measurement were calculated. The results revealed that removing the flattening filter led to a change within 0.3% in the relationship between %dd(10) x and (L¯/ρ)airwater, whereby the relationship between TPR1020 and (L¯/ρ)airwater changed up to 0.8% for high energy photon beams. However, TPR1020 was a good predictor of (L¯/ρ)airwater for both types of linear accelerator with energies filter within 1.1% and 1.6% was observed for TPR1020 and %dd(10) x respectively. The results of this study have shown that removing the flattening filter led to a change in the relationship between the well-known beam quality specifiers and dosimetric quantities at the point of measurement

  6. Influence of the Integral Quality Monitor transmission detector on high energy photon beams: A multi-centre study.

    Science.gov (United States)

    Casar, Bozidar; Pasler, Marlies; Wegener, Sonja; Hoffman, David; Talamonti, Cinzia; Qian, Jianguo; Mendez, Ignasi; Brojan, Denis; Perrin, Bruce; Kusters, Martijn; Canters, Richard; Pallotta, Stefania; Peterlin, Primoz

    2017-09-01

    The influence of the Integral Quality Monitor (IQM) transmission detector on photon beam properties was evaluated in a preclinical phase, using data from nine participating centres: (i) the change of beam quality (beam hardening), (ii) the influence on surface dose, and (iii) the attenuation of the IQM detector. For 6 different nominal photon energies (4 standard, 2 FFF) and square field sizes from 1×1cm 2 to 20×20cm 2 , the effect of IQM on beam quality was assessed from the PDD 20,10 values obtained from the percentage dose depth (PDD) curves, measured with and without IQM in the beam path. The change in surface dose with/without IQM was assessed for all available energies and field sizes from 4×4cm 2 to 20×20cm 2 . The transmission factor was calculated by means of measured absorbed dose at 10cm depth for all available energies and field sizes. (i) A small (0.11-0.53%) yet statistically significant beam hardening effect was observed, depending on photon beam energy. (ii) The increase in surface dose correlated with field size (pphoton energies except for 18MV. The change in surface dose was smaller than 3.3% in all cases except for the 20×20cm 2 field and 10MV FFF beam, where it reached 8.1%. (iii) For standard beams, transmission of the IQM showed a weak dependence on the field size, and a pronounced dependence on the beam energy (0.9412 for 6MV to 0.9578 for 18MV and 0.9440 for 6MV FFF; 0.9533 for 10MV FFF). The effects of the IQM detector on photon beam properties were found to be small yet statistically significant. The magnitudes of changes which were found justify treating IQM either as tray factors within the treatment planning system (TPS) for a particular energy or alternatively as modified outputs for specific beam energy of linear accelerators, which eases the introduction of the IQM into clinical practice. Copyright © 2017. Published by Elsevier GmbH.

  7. Influence of the Integral Quality Monitor transmission detector on high energy photon beams. A multi-centre study

    Energy Technology Data Exchange (ETDEWEB)

    Casar, Bozidar [Institute of Oncology, Ljubljana (Slovenia). Dept. of Radiation Physics; Pasler, Marlies [Lake Constance Radiation Oncology Center, Singen and Friedrichshafen (Germany); Wegener, Sonja [Wuerzburg Univ. (Germany). Dept. of Radiation Oncology; and others

    2017-10-01

    The influence of the Integral Quality Monitor (IQM) transmission detector on photon beam properties was evaluated in a preclinical phase, using data from nine participating centres: (i) the change of beam quality (beam hardening), (ii) the influence on surface dose, and (iii) the attenuation of the IQM detector. For 6 different nominal photon energies (4 standard, 2 FFF) and square field sizes from 1 x 1 cm{sup 2} to 20 x 20 cm{sup 2}, the effect of IQM on beam quality was assessed from the PDD{sub 20,10} values obtained from the percentage dose depth (PDD) curves, measured with and without IQM in the beam path. The change in surface dose with/without IQM was assessed for all available energies and field sizes from 4 x 4 cm{sup 2} to 20 x 20 cm{sup 2}. The transmission factor was calculated by means of measured absorbed dose at 10 cm depth for all available energies and field sizes. (i) A small (0.11-0.53%) yet statistically significant beam hardening effect was observed, depending on photon beam energy. (ii) The increase in surface dose correlated with field size (p < 0.01) for all photon energies except for 18 MV. The change in surface dose was smaller than 3.3% in all cases except for the 20 x 20 cm{sup 2} field and 10 MV FFF beam, where it reached 8.1%. (iii) For standard beams, transmission of the IQM showed a weak dependence on the field size, and a pronounced dependence on the beam energy (0.9412 for 6 MV to 0.9578 for 18 MV and 0.9440 for 6 MV FFF; 0.9533 for 10 MV FFF). The effects of the IQM detector on photon beam properties were found to be small yet statistically significant. The magnitudes of changes which were found justify treating IQM either as tray factors within the treatment planning system (TPS) for a particular energy or alternatively as modified outputs for specific beam energy of linear accelerators, which eases the introduction of the IQM into clinical practice.

  8. SU-F-T-276: Source Modeling and VMAT Quality Assurance Referring to the TrueBeam Representative Beam Data for Eclipse

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Q [Beijing Hospital, Beijing (China)

    2016-06-15

    Purpose: To study quality assurance (QA) of volumetric modulated arc therapy (VMAT) after the 6MV and 10MV photon beam source modeling, referring to the Varian TrueBeam representative beam data for Eclipse. Methods: The source model needs specific measured beam data, such as PDDs and profiles, diagonal profile, output factors (OFs), and MLC transmission factor (TF) and dosimetric leaf gap (DLG), et al. We downloaded the representative data from myVarian website, which includes TrueBeam 4MV-15MV photon beam data and 6MeV-22MeV electron beam data in w2CAD file format for use with Eclipse and in Excel spreadsheet format for use in data comparison. The beam data in W2CAD format can be imported into the Eclipse system and calibrated for use, as appropriate. We used PTW MP3 water tank to measure the beam data in some typical field sizes, and compared the measured data with the representative data. We found that the PDDs, profiles and OFs are similar. However according to some papers and our measurements, we decided that our MLC TF and DLG are 1.58 and 1.33 (6MV), 1.79 and 1.57 (10MV), respectively. After we had configured the anisotropic analytical algorithm (AAA) with the representative data in Eclipse, we also have done dosimetric verification for 88 VMAT plans. Results: The end-to-end test procedures of VMAT were performed for 6MV and 10MV energy modes. The NE Farmer ion chamber mean measurements showed 1.2% (6MV, 38 cases) and 1.2% (10MV, 50 cases) between measurement and calculation; the Sun Nuclear ArcCheck mean measurements demonstrated gamma pass rates are as followings: 98.9%, 93.2%, 61.0% for 6MV, and 98.9%, 91.9%, 59.5% for 10MV, using 3%/3mm, 2%/2mm, 1%/1mm, 10% threshold criteria, respectively. Conclusion: The representative data is applicable to our TrueBeam for the VMAT plan, though our MLC factors are a little different, and its patientspecific QA is good.

  9. Factors influencing quality of life in asthmatics

    DEFF Research Database (Denmark)

    Al-kalemji, Abir; Petersen, Karin Dam; Sørensen, Jan

    2013-01-01

    INTRODUCTION: The quality of life (QOL) in persons with asthma is reduced and different factors such as demography, asthma severity and psychiatric comorbidity play an influential role. However, little is known about the interplay of these factors. OBJECTIVE: To describe QOL in relation to asthma...

  10. Tilting the jaw to improve the image quality or to reduce the dose in cone-beam computed tomography

    International Nuclear Information System (INIS)

    Luckow, Marlen; Deyhle, Hans; Beckmann, Felix; Dagassan-Berndt, Dorothea; Müller, Bert

    2011-01-01

    Objective: The image quality in cone-beam computed tomography (CBCT) should be improved tilting the mandible that contains two dental titanium implants, within the relevant range of motion. Materials and methods: Using the mandible of a five-month-old pig, CBCT was performed varying the accelerating voltage, beam current, the starting rotation angle of the mandible in the source-detector plane and the tilt angles of the jaw with respect to the source-detector plane. The different datasets were automatically registered with respect to micro CT data to extract the common volume and the deviance to the pre-defined standard that characterizes the image quality. Results: The variations of the accelerating voltage, beam current and the rotation within the source-detection plane provided the expected quantitative behavior indicating the appropriate choice of the imaging quality factor. The tilting of the porcine mandible by about 14° improves the image quality by almost a factor of two. Conclusions: The tilting of the mandible with two dental implants can be used to significantly reduce the artifacts of the strongly X-ray absorbing materials in the CBCT images. The comparison of 14° jaw tilting with respect to the currently recommended arrangement in plane with the teeth demonstrates that the applied exposure time and the related dose can be reduced by a factor of four without decreasing the image quality.

  11. Beam-quality measurements using a spatial light modulator

    CSIR Research Space (South Africa)

    Schulze, C

    2012-11-01

    Full Text Available We present a fast and easy technique for measuring the beam propagation ratio, M2, of laser beams using a spatial light modulator. Our technique is based on digitally simulating the free-space propagation of light, thus eliminating the need...

  12. TLD postal dose quality audit service for Co-60 beams in reference conditions in Cuba

    International Nuclear Information System (INIS)

    Gutierrez Lores, S.; Walwyn Salas, G.; Alonso Villanueva, G.

    2008-01-01

    This report presents the methodology and experience of the Cuban's Secondary Standard Dosimetry Laboratory for the implementation of postal dose quality audits service for Co-60 beams in reference conditions, using TLDs. Under coordinated research project (Contract 10794) were bought (TLD -100) Tl rods type JR 1152F made in China, with dimensions of 6 mm x 1 mm x 1 mm. All of these rods were identified individually with a consecutive number made over one of its sides, using a fine tip of graphite. The method used to determinate the individual sensibility of the TL detectors was: irradiating a group of them, with the same history of irradiation and readout (100 rods approximately), four serial times in the same geometrical conditions, to read them out and to attribute to each of them a sensitivity factor. This sensitivity factor is equal to average for the 4 cycle of irradiation and readout of the quote between the TL readout from dosimeter i and the mean of all values for each cycle. The TLD signal was read using HARSHAW 2000C/B reader. The results obtained in the external verification of the accuracy of the dose determination by the TLD system were performed in cooperation with IAEA Dosimetry Laboratory at Seibersdorf in different years are shown, the results obtained of the quality audits carried out to the different services of radiotherapy of the country are analysed also. The quality audits are an useful tool for the improvement of the accuracy in the dosimetry of clinical beams of radiotherapy with Co-60, contributing this way to the improvement of the life quality to cancer patients of the Cuban system of health. (author)

  13. A sextupole ion beam guide to improve the efficiency and beam quality at IGISOL

    International Nuclear Information System (INIS)

    Karvonen, P.; Moore, I.D.; Sonoda, T.; Kessler, T.; Penttilae, H.; Peraejaervi, K.; Ronkanen, P.; Aystoe, J.

    2008-01-01

    The laser ion source project at the IGISOL facility, Jyvaeskylae, has motivated the development and construction of an rf sextupole ion beam guide (SPIG) to replace the original skimmer electrode. The SPIG has been tested both off-line and on-line in proton-induced fission, light-ion and heavy-ion induced fusion-evaporation reactions and, in each case, has been directly compared to the skimmer system. For both fission and light-ion induced fusion, the SPIG has improved the mass-separated ion yields by a factor of typically 4-8. Correspondingly, the transmission efficiency of both systems has been studied in simulations with and without space charge effects. The transport capacity of the SPIG has been experimentally determined to be ∼10 12 ions s -1 before space charge effects start to take effect. A direct comparison with the simulation has been made using data obtained via light-ion fusion evaporation. Both experiment and simulation show an encouraging agreement as a function of current extracted from the ion guide.

  14. Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system

    International Nuclear Information System (INIS)

    Breitbach, Elizabeth K.; Maltz, Jonathan S.; Gangadharan, Bijumon; Bani-Hashemi, Ali; Anderson, Carryn M.; Bhatia, Sudershan K.; Stiles, Jared; Edwards, Drake S.; Flynn, Ryan T.

    2011-01-01

    Purpose: To quantify the improvement in megavoltage cone beam computed tomography (MVCBCT) image quality enabled by the combination of a 4.2 MV imaging beam line (IBL) with a carbon electron target and a detector system equipped with a novel sintered pixelated array (SPA) of translucent Gd 2 O 2 S ceramic scintillator. Clinical MVCBCT images are traditionally acquired with the same 6 MV treatment beam line (TBL) that is used for cancer treatment, a standard amorphous Si (a-Si) flat panel imager, and the Kodak Lanex Fast-B (LFB) scintillator. The IBL produces a greater fluence of keV-range photons than the TBL, to which the detector response is more optimal, and the SPA is a more efficient scintillator than the LFB. Methods: A prototype IBL + SPA system was installed on a Siemens Oncor linear accelerator equipped with the MVision TM image guided radiation therapy (IGRT) system. A SPA strip consisting of four neighboring tiles and measuring 40 cm by 10.96 cm in the crossplane and inplane directions, respectively, was installed in the flat panel imager. Head- and pelvis-sized phantom images were acquired at doses ranging from 3 to 60 cGy with three MVCBCT configurations: TBL + LFB, IBL + LFB, and IBL + SPA. Phantom image quality at each dose was quantified using the contrast-to-noise ratio (CNR) and modulation transfer function (MTF) metrics. Head and neck, thoracic, and pelvic (prostate) cancer patients were imaged with the three imaging system configurations at multiple doses ranging from 3 to 15 cGy. The systems were assessed qualitatively from the patient image data. Results: For head and neck and pelvis-sized phantom images, imaging doses of 3 cGy or greater, and relative electron densities of 1.09 and 1.48, the CNR average improvement factors for imaging system change of TBL + LFB to IBL + LFB, IBL + LFB to IBL + SPA, and TBL + LFB to IBL + SPA were 1.63 (p -8 ), 1.64 (p -13 ), 2.66 (p -9 ), respectively. For all imaging doses, soft tissue contrast was more

  15. Determination of quality factors by microdosimetry

    International Nuclear Information System (INIS)

    Al-Affan, I.A.M.; Watt, D.E.

    1987-01-01

    The application of microdose parameters for the specification of a revised scale of quality factors which would be applicable at low doses and dose rates is examined in terms of an original proposal by Rossi. Two important modifications are suggested to enable an absolute scale of quality factors to be constructed. Allowance should be made to allow for the dependence of the saturation threshold of lineal energy on the type of heavy charged particle. Also, an artificial saturation threshold should be introduced for electron tracks as a means of modifying the measurements made in the microdosimeter to the more realistic site sizes of nanometer dimensions. The proposed absolute scale of quality factors nicely encompasses the high RBEs of around 3 observed at low doses for tritium β rays and is consistent with the recent recommendation of the ICRP that the quality factor for fast neutrons be increased by a factor of two, assuming that there is no biological repair for the reference radiation. (orig.)

  16. Image-rotating cavity designs for improved beam quality in nanosecond optical parametric oscillators

    International Nuclear Information System (INIS)

    Smith, Arlee V.; Bowers, Mark S.

    2001-01-01

    We show by computer simulation that high beam quality can be achieved in high-energy, nanosecond optical parametric oscillators by use of image-rotating resonators. Lateral walk-off between the signal and the idler beams in a nonlinear crystal creates correlations across the beams in the walk off direction, or equivalently, creates a restricted acceptance angle. These correlations can improve the beam quality in the walk-off plane. We show that image rotation or reflection can be used to improve beam quality in both planes. The lateral walk-off can be due to birefringent walk-off in type II mixing or to noncollinear mixing in type I or type II mixing

  17. Analytic representation of the backscatter correction factor at the exit of high energy photon beams

    International Nuclear Information System (INIS)

    Kappas, K.; Rosenwald, J.C.

    1991-01-01

    In high-energy X-ray beams, the dose calculated near the exit surface under electronic equilibrium conditions is generally over-estimated since it is derived from measurements performed in water with large thickness of backscattering material. The resulting error depends on a number of parameters such as beam energy, field dimension, thickness of overlying and underlying material. The authors have systematically measured for 4 different energies and for different para- meters and for different combinations of the above parameters, the reduction of dose due to backscatter. This correction is expressed as a multiplicative factor, called 'Backscatter Correction Factor' (BCF). This BCF is larger for lower energies, larger field sizes and larger depths. The BCF has been represented by an analytical expression which involves an exponential function of the backscattering thickness and linear relationships with depth field size and beam quality index. Using this expression, the BCF can be calculated within 0.5% for any conditions in the energy range investigated. (author). 14 refs.; 4 figs.; 3 tabs

  18. Cone beam computed tomography radiation dose and image quality assessments.

    Science.gov (United States)

    Lofthag-Hansen, Sara

    2010-01-01

    Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and

  19. Saturne II: characteristics of the proton beam, field qualities and corrections, acceleration of the polarized protons

    International Nuclear Information System (INIS)

    Laclare, J.-L.

    1978-01-01

    Indicated specifications of Saturne II are summed up: performance of the injection system, quality of the guidance field (magnetic measurements and multipolar corrections), transverse and longitudinal instabilities, characteristics of the beam stored in the machine and of the extracted beam. The problem of depolarization along the acceleration cycle is briefly discussed (1 or 2% between injection and 3 GeV) [fr

  20. Factors influencing microinjection molding replication quality

    Science.gov (United States)

    Vera, Julie; Brulez, Anne-Catherine; Contraires, Elise; Larochette, Mathieu; Trannoy-Orban, Nathalie; Pignon, Maxime; Mauclair, Cyril; Valette, Stéphane; Benayoun, Stéphane

    2018-01-01

    In recent years, there has been increased interest in producing and providing high-precision plastic parts that can be manufactured by microinjection molding: gears, pumps, optical grating elements, and so on. For all of these applications, the replication quality is essential. This study has two goals: (1) fabrication of high-precision parts using the conventional injection molding machine; (2) identification of robust parameters that ensure production quality. Thus, different technological solutions have been used: cavity vacuuming and the use of a mold coated with DLC or CrN deposits. AFM and SEM analyses were carried out to characterize the replication profile. The replication quality was studied in terms of the process parameters, coated and uncoated molds and crystallinity of the polymer. Specific studies were processed to quantify the replicability of injection molded parts (ABS, PC and PP). Analysis of the Taguchi experimental designs permits prioritization of the impact of each parameter on the replication quality. A discussion taking into account these new parameters and the thermal and spreading properties on the coatings is proposed. It appeared that, in general, increasing the mold temperature improves the molten polymer fill in submicron features except for the steel insert (for which the presence of a vacuum is the most important factor). Moreover, the DLC coating was the best coating to increase the quality of the replication. This result could be explained by the lower thermal diffusivity of this coating. We noted that the viscosity of the polymers is not a primordial factor of the replication quality.

  1. Exploring Factors That Influence Quality Literature Circles

    Science.gov (United States)

    Young, Chase; Mohr, Kathleen A. J.

    2018-01-01

    Research indicates that literature circles are an authentic means for literacy development that students typically enjoy. To better understand the potential value and to add to the research base regarding literature circles, this study, involving 17 fourth graders, explores factors that may influence the quality of literature discussions,…

  2. Quality control in the geometry of the beam of a unit of volumetric modulated arcotheraphy

    International Nuclear Information System (INIS)

    Clemente Gutierrez, F.; Ramirez Ros, J. C.; Cabello Murillo, E.; Casa de Julian, M. A. de la

    2011-01-01

    We report here the evidence offered for the regular quality control (monthly) beam geometry (flatness and symmetry) for a unit of 6 MV Elekta Synergy with VMAT, belonging to the Radiation Oncology Service of the Defense Central Hospital Gomez Ulla.

  3. Diode pumped 1kHz high power Nd:YAG laser with excellent beam quality

    NARCIS (Netherlands)

    Godfried, Herman; Godfried, H.P; Offerhaus, Herman L.

    1997-01-01

    The design and operation of a one kilohertz diode pumped all solid-state Nd:YAG master oscillator power amplifier system with a phase conjugate mirror is presented. The setup allows high power scaling without reduction in beam quality.

  4. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    OpenAIRE

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Kuncic, Zdenka; Keall, Paul J.

    2014-01-01

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An inv...

  5. Stability of electron-beam energy monitor for quality assurance of the electron-beam energy from radiotherapy accelerators

    International Nuclear Information System (INIS)

    Chida, Koichi; Zuguchi, Masayuki; Saito, Haruo; Takai, Yoshihiro; Mitsuya, Masatoshi; Sakakida, Hideharu; Yamada, Shogo; Kohzuki, Masahiro

    2002-01-01

    Information on electron energy is important in planning radiation therapy using electrons. The Geske 3405 electron beam energy monitor (Geske monitor, PTW Nuclear Associates, Carle Place, NY, USA) is a device containing nine ionization chambers for checking the energy of the electron beams produced by radiotherapy accelerators. We wondered whether this might increase the likelihood of ionization chamber trouble. In spite of the importance of the stability of such a quality assurance (QA) device, there are no reports on the stability of values measured with a Geske monitor. The purpose of this paper was therefore to describe the stability of a Geske monitor. It was found that the largest coefficient of variation (CV) of the Geske monitor measurements was approximately 0.96% over a 21-week period. In conclusion, the stability of Geske monitor measurements of the energy of electron beams from a linear accelerator was excellent. (author)

  6. Longitudinal beam parameters and quality checks of the LHC beam in the SPS: further results and comparisons

    CERN Document Server

    Papotti, G; Linnecar, T; Shaposhnikova, E; Tückmantel, Joachim; CERN. Geneva. AB Department

    2008-01-01

    Controlled longitudinal emittance blow up is used, along with other measures, to stabilize the nominal LHC beam in the SPS. Two Machine Development studies (MDs) were carried out in 2007 to evaluate the effectiveness of different noise settings for the longitudinal blow up of the beam. The noise settings are affected by both the presence of the 800 MHz RF system and intensity effects which modify the synchrotron frequency distribution inside the bunch. The results for the first MD are reported in Note [1]. This Note reports on the results of the second MD, carried out on 2007-10-17, as well as the comparison between the two in order to analyse the differences between the two occasions. Figures of merit are used that allow rapid evaluation of the quality of the beam as for example stability and bunch length uniformity across batches.

  7. SU-E-T-577: Obliquity Factor and Surface Dose in Proton Beam Therapy

    International Nuclear Information System (INIS)

    Das, I; Andersen, A; Coutinho, L

    2015-01-01

    Purpose: The advantage of lower skin dose in proton beam may be diminished creating radiation related sequalae usually seen with photon and electron beams. This study evaluates the surface dose as a complex function of beam parameters but more importantly the effect of beam angle. Methods: Surface dose in proton beam depends on the beam energy, source to surface distance, the air gap between snout and surface, field size, material thickness in front of surface, atomic number of the medium, beam angle and type of nozzle (ie double scattering, (DS), uniform scanning (US) or pencil beam scanning (PBS). Obliquity factor (OF) is defined as ratio of surface dose in 0° to beam angle Θ. Measurements were made in water phantom at various beam angles using very small microdiamond that has shown favorable beam characteristics for high, medium and low proton energy. Depth dose measurements were performed in the central axis of the beam in each respective gantry angle. Results: It is observed that surface dose is energy dependent but more predominantly on the SOBP. It is found that as SSD increases, surface dose decreases. In general, SSD, and air gap has limited impact in clinical proton range. High energy has higher surface dose and so the beam angle. The OF rises with beam angle. Compared to OF of 1.0 at 0° beam angle, the value is 1.5, 1.6, 1,7 for small, medium and large range respectively for 60 degree angle. Conclusion: It is advised that just like range and SOBP, surface dose should be clearly understood and a method to reduce the surface dose should be employed. Obliquity factor is a critical parameter that should be accounted in proton beam therapy and a perpendicular beam should be used to reduce surface dose

  8. Beam Quality Preservation in the CERN PS-SPS Complex

    CERN Multimedia

    Arduini, Gianluigi

    2004-01-01

    The LHC will require beams of unprecedented transverse and longitudinal brightness. Their production imposes tight constraints on the emittance growth in each element of the LHC injector chain, namely the PS-SPS Accelerator Complex. The problems encountered at the different stages of the acceleration in the complex span a wide range of topics, such as injection matching, RF gymnastics, space charge, transverse and longitudinal single- and coupled-bunch instabilities, and electron cloud effects. The measurement techniques developed and applied to identify and study the various sources of emittance dilution to the high precision required for the LHC beams and the solutions found to control such phenomena are illustrated.

  9. Design of RF chopper system for improving beam quality in FEL injector with thermionic gun

    International Nuclear Information System (INIS)

    Chen, Q.; Qin, B.; Tan, P.; Hu, T.; Pei, Y.; Zhang, F.

    2014-01-01

    For a linac-based Free Electron Laser (FEL), good beam quality largely contributes to the success of the final radiation. An imperfection confronted with the HUST THz-FEL facility is the long beam tail that emerges in the electron gun and exists through the whole beam line. This paper proposes to deploy a chopper system after the electron gun to truncate the beam tails before they enter into the linac. Physical dimensions of the chopper cavity are discussed in detail and we have developed and derived new analytical expressions applying to all frequencies for the optimal design. Also, technical issues of the cavity are considered. Beam dynamic simulation is performed to examine the truncation effect and the results show that more than 78% of the beam tail can be removed effectively, while preserving the emittance and energy spread in acceptable level

  10. On beam quality and stopping power ratios for high-energy x-rays

    International Nuclear Information System (INIS)

    Johnsson, S.A.; Ceberg, C.P.; Knoeoes, T.; Nilsson, P.

    2000-01-01

    The aim of this work is to quantitatively compare two commonly used beam quality indices, TPR(20/10) and %dd(10) x , with respect to their ability to predict stopping power ratios (water to air), s w,air , for high-energy x-rays. In particular, effects due to a varied amount of filtration of the photon beam will be studied. A new method for characterizing beam quality is also presented, where the information we strive to obtain is the moments of the spectral distribution. We will show how the moments enter into a general description of the transmission curve and that it is possible to correlate the moments to s w,air with a unique and simple relationship. Comparisons with TPR(20/10) and %dd(10) x show that the moments are well suited for beam quality specification in terms of choosing the correct s w,air . (author)

  11. Quality factors of nonideal micro pillars

    DEFF Research Database (Denmark)

    Gregersen, Niels; Nielsen, Torben Roland; Tromborg, Bjarne

    2007-01-01

    The influence of fabrication-induced imperfections and material absorption on the quality (Q) factor of a microcavity pillar is studied numerically. The dependence on sidewall inclination, selective underetch, and intrinsic loss is quantified. The authors show that imperfections can lead to an im...... to an improvement in Q and that a sidewall inclination angle of less than 1° causes a dramatic change in the Q factor. The variations in Q can be attributed to a delicate balance between effective index contrasts, mode overlap, and higher-order mode contributions....

  12. The quality factor in ionising radiation

    International Nuclear Information System (INIS)

    Chen Changmao

    1990-12-01

    The existing quality factors for ionizing radiation and the Q values recommended by ICRU report 40 are briefly introduced, and the relevant aspects are also discussed. It is recommended that the new Q values presented by ICRU should not be adopted in protection radiation practices, but the ultimate decision from ICRP should be noted. It is pointed out that the relevant academic discussion should be developed at present, in order to study the position and policy which should be taken. (author)

  13. High quality beams of MV/cm THz pulses generated from DSTMS

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Jepsen, Peter Uhd

    2015-01-01

    A beam characterization of a THz beam generated from the organic crystal DSTMS is presented. The simple, collinear phase-matching geometry for this crystal results in an M2 factor below 1.5, resulting in a focused field strength of more than 4 MV/cm....

  14. Factors that Influence Quality Service of Teachers

    Directory of Open Access Journals (Sweden)

    M. Nur Mustafa

    2013-07-01

    Full Text Available Education as a profession requires a thorough commitment and sincerity among educators in guiding and shaping the patterns of learning toward forming identities and lead change in the students. As an adult with a lot of knowledge and experience, classroom becomes an important medium for the delivery and access to knowledge to the students in an instructional condition that effectively and efficiently. Therefore, all educators need to prepare themselves to face challenges to deal with children as a leader in charge in constructing a conducive and persuasive educational relationship. Important characteristics in this context is how to create a memorable delivery systems that meet the standard qualities and aligned with the education laws enforced. As a teacher who has received training from experts and civil servants thus all actions taken should be sincere, open, meet the service specification that gives attention to the self-esteem of the students with a good service, quality, and meet their needs. Therefore, this study will discuss the main factors that affect the quality of service to the students among the teachers namely motivation and professional competence. Selected samples in this study were 327 teachers from Secondary School in Pekanbaru. This study has shown a clear interest in improving the quality of motivation and the quality of service of teachers to the students. The aspects of the professional competence of teachers are still experiencing problems in applying the knowledge and skills to lead and manage the classroom inrealizing   a conducive environment.

  15. Study of the tomographic image quality provided by a conical beam system kilo voltage

    International Nuclear Information System (INIS)

    Garayoa Roca, J.; Castro Tejero, P.

    2011-01-01

    Imaging systems play an increasingly important role in radiotherapy, and to ensure the quality of the process, you must know the characteristics and limitations of available imaging systems. In this study we sought to evaluate the image quality of an IGRT system based on a kilo voltage cone beam.

  16. Cone Beam CT vs. Fan Beam CT: A Comparison of Image Quality and Dose Delivered Between Two Differing CT Imaging Modalities.

    Science.gov (United States)

    Lechuga, Lawrence; Weidlich, Georg A

    2016-09-12

    A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities-fan beam and cone beam-was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation. The results indicate that fan beam CT produces superior images to that of on-board imaging (OBI) cone beam CT systems, while providing a considerably less dose to the patient.

  17. Constancy check of beam quality in conventional diagnostic X-ray equipment

    International Nuclear Information System (INIS)

    Costa, Alessandro M.; Badin, Romulo S.; Leite, Marina S.; Caldas, Linda V.E.

    2008-01-01

    A tandem ionization chamber was developed for quality control programs of X-ray equipment used in conventional radiography and mammography. A methodology for the use of the tandem chamber in the constancy check of diagnostic X-ray beam qualities was established. The application at a medical X-ray imaging facility of this established methodology is presented. The use of the tandem chamber in the constancy check of diagnostic X-ray beam qualities is a useful method to control the performance of the X-ray equipment

  18. Dual-energy contrast-enhanced breast tomosynthesis: optimization of beam quality for dose and image quality

    International Nuclear Information System (INIS)

    Samei, Ehsan; Saunders, Robert S Jr

    2011-01-01

    Dual-energy contrast-enhanced breast tomosynthesis is a promising technique to obtain three-dimensional functional information from the breast with high resolution and speed. To optimize this new method, this study searched for the beam quality that maximized image quality in terms of mass detection performance. A digital tomosynthesis system was modeled using a fast ray-tracing algorithm, which created simulated projection images by tracking photons through a voxelized anatomical breast phantom containing iodinated lesions. The single-energy images were combined into dual-energy images through a weighted log subtraction process. The weighting factor was optimized to minimize anatomical noise, while the dose distribution was chosen to minimize quantum noise. The dual-energy images were analyzed for the signal difference to noise ratio (SdNR) of iodinated masses. The fast ray-tracing explored 523 776 dual-energy combinations to identify which yields optimum mass SdNR. The ray-tracing results were verified using a Monte Carlo model for a breast tomosynthesis system with a selenium-based flat-panel detector. The projection images from our voxelized breast phantom were obtained at a constant total glandular dose. The projections were combined using weighted log subtraction and reconstructed using commercial reconstruction software. The lesion SdNR was measured in the central reconstructed slice. The SdNR performance varied markedly across the kVp and filtration space. Ray-tracing results indicated that the mass SdNR was maximized with a high-energy tungsten beam at 49 kVp with 92.5 μm of copper filtration and a low-energy tungsten beam at 49 kVp with 95 μm of tin filtration. This result was consistent with Monte Carlo findings. This mammographic technique led to a mass SdNR of 0.92 ± 0.03 in the projections and 3.68 ± 0.19 in the reconstructed slices. These values were markedly higher than those for non-optimized techniques. Our findings indicate that dual

  19. Application of a tandem ionization chamber in a quality control program of X-ray beams, radiotherapy level

    International Nuclear Information System (INIS)

    Yoshizumi, Maira T.; Caldas, Linda V.E.

    2008-01-01

    A tandem ionization chamber, developed at the Instituto de Pesquisas Energeticas e Nucleares (IPEN), for X radiation beams, radiotherapy level, was applied into a quality control program of the Calibration Laboratory of IPEN. This ionization chamber is composed by two ionization chambers, with a volume of 0.6 cm 3 each one. Its inner plane-parallel electrodes and guard rings are made of different materials: one is made of aluminum and the other is made of graphite. Because of this difference in materials, the ionization chamber forms a tandem system. The relative response of the calibration factors of both sides of the chamber allows an easy verification of the X-ray beam qualities stability. The ionization chamber was submitted to some tests to verify the stability of its response: leakage current before and after exposure, repeatability and reproducibility. The performance of the ionization chamber was satisfactory. (author)

  20. Quality factor: conceptual problems and practical solutions

    International Nuclear Information System (INIS)

    Dennis, J.A.

    1988-01-01

    In the past ten years a growing divide has become apparent between the dosimetric concepts designed to provide measures of stochastic risks and those designed for the measurement and control of exposures to radiation. Those designed to provide estimates of risk, e.g. effective dose equivalent, might need to be further refined to incorporate the latest scientific beliefs and evidence about the dependence on radiation quality and dose rate as well as on age and sex. Both animal and human evidence strongly supports a belief that different tissues and different types of neoplasm will have different dependencies on radiation quality and dose rate. For practical purposes of risk estimation it is necessary to select the same values for all human neoplasms. There are reasons for using life shortening in animals as a basis for this purpose, but the data for the dependence on the whole range of radiation qualities is meagre. To provide some stability for the new concepts of measurement and calibration it may be better to accommodate changing perceptions on radiation risks by specifying different levels of exposure for different types of radiation without changing the current quality factors for the measurement quantities. (author)

  1. TLD Postal service for quality audits of beams of Co-60 in reference conditions in Cuba

    International Nuclear Information System (INIS)

    Gutierrez L, S.; Walwyn S, G.; Alonso V, G.

    2006-01-01

    Purpose: To describe the methodology and experience of the Secondary Laboratory of Dosimetric Calibration of Cuba in the establishment of the TLD Postal Service for quality audits of beams of Co-60 in reference conditions. Materials and methods: Through the Coordinated Project of Research (Contract 10794) its was bought 200 solid thermoluminescent detectors of LiF: Mg, Ti (TLD-100) in micro bars form with dimensions of 6 x 1 x 1 mm and of the JR 1152F type manufactured in China. All these detectors were identified individually with a serial number on one of its faces, using a graphite fine sheet. Those detectors for its irradiation are introduced in cylindrical plastic capsules developed and used by the International Atomic Energy Agency (IAEA) in the Audit Postal Service of Dose IAEA/WHO, the capsules have one cavity equal to 3 mm for that is necessary to recover this cavity with a fine plastic tube so that the detectors remain immobile during the irradiation. The method used to determine the individual sensitivity of the thermoluminescent detectors is: to irradiate a detectors group (100 micro bars) 4 times in those same geometric conditions, with the same irradiation history and reading, then it is determine for each detector a sensitivity factor equal to the average of those readings obtained for the 4 irradiation cycles for each i detector among the average of all the reading values obtained during the 4 cycles. The thermoluminescent signal is obtained with a Harshaw 2000C/B reader manual. Results: The satisfactory results obtained in the verification of the calibration of the TLD system, using the reference irradiation service of the Seibersdorf Dosimetry Laboratory of the IAEA in three different years are shown. The results of the audits carried out to the different radiotherapy services of the country in different years are also presented. Conclusions: The experience with the detectors acquired in the project demonstrates that with an appropriate

  2. Effect of electron beam on quality and physiological metabolism of blueberry

    International Nuclear Information System (INIS)

    Zhou Huijuan; Ye Zhengwen; Zhang Xueying; Su Mingshen; Du Jihong; Zhang Minqian

    2013-01-01

    In order to explore safe, simple and effective storage technology, experiment was conducted with 'ai li ao te' blueberry for studying the effect of electron beam on quality and physiological metabolism. Fruit was stored at temperature of (1 ± 0.5)℃, with RH of 80% ∼ 85%, and treated with electron beam of 0.5, 1, 1.5, 2, 3 kGy. The results showed that the proper dose of electron beam could decline the bad fruit rate and weightlessness, restrain respiration intensity, alleviate the decline of soluble solids, acid and Vc content. Meanwhile it did not have significant negative effects on pulp colour. All these showed that electron beam of 1 kGy treatment could keep the best storage quality of blueberry, keep the sound berry and weightlessness rate at > 90% and < 10% respectively, prolong the effective storage time from 30d to 60d. (authors)

  3. Formation of a high quality electron beam using photo cathode RF electron gun

    International Nuclear Information System (INIS)

    Washio, Masakazu

    2000-01-01

    Formation of a high quality electron beam using photo cathode RF electron gun is expected for formation of a next generation high brilliant X-ray beam and a source for electron and positron collider. And, on a field of material science, as is possible to carry out an experiment under ultra short pulse and extremely high precision in time, it collects large expectation. Recently, formation of high quality beam possible to develop for multi directions and to use by everyone in future has been able to realize. Here were explained on electron beam source, principle and component on RF electron gun, working features on RF gun, features and simulation of RF gun under operation, and some views in near future. (G.K.)

  4. Yogurt, diet quality and lifestyle factors.

    Science.gov (United States)

    Panahi, S; Fernandez, M A; Marette, A; Tremblay, A

    2017-05-01

    Yogurt consumption has been associated with healthy dietary patterns and lifestyles, better diet quality and healthier metabolic profiles. Studies have shown that frequent yogurt consumers do not only have higher nutrient intakes, but also an improved diet quality, which includes higher consumption of fruits and vegetables, whole grains, and dairy compared with low or non-consumers indicating better compliance with dietary guidelines. Recent epidemiological and clinical evidence suggests that yogurt contributes to better metabolic health because of its effects on the control of body weight, energy homeostasis and glycemic control. Furthermore, yogurt consumers have been shown to be more physically active (⩾ 2 h/week), smoke less, have higher education and knowledge of nutrition compared with non-consumers. Thus, yogurt consumption may be considered a signature of a healthy diet through its nutritional content, impact on metabolic health including the control of energy balance, body weight and glycemia and its relationships with healthier behaviors and lifestyle factors.

  5. Radiochromic film calibration for the RQT9 quality beam

    Science.gov (United States)

    Costa, K. C.; Gomez, A. M. L.; Alonso, T. C.; Mourao, A. P.

    2017-11-01

    When ionizing radiation interacts with matter it generates energy deposition. Radiation dosimetry is important for medical applications of ionizing radiation due to the increasing demand for diagnostic radiology and radiotherapy. Different dosimetry methods are used and each one has its advantages and disadvantages. The film is a dose measurement method that records the energy deposition by the darkening of its emulsion. Radiochromic films have a little visible light sensitivity and respond better to ionizing radiation exposure. The aim of this study is to obtain the resulting calibration curve by the irradiation of radiochromic film strips, making it possible to relate the darkening of the film with the absorbed dose, in order to measure doses in experiments with X-ray beam of 120 kV, in computed tomography (CT). Film strips of GAFCHROMIC XR-QA2 were exposed according to RQT9 reference radiation, which defines an X-ray beam generated from a voltage of 120 kV. Strips were irradiated in "Laboratório de Calibração de Dosímetros do Centro de Desenvolvimento da Tecnologia Nuclear" (LCD / CDTN) at a dose range of 5-30 mGy, corresponding to the range values commonly used in CT scans. Digital images of the irradiated films were analyzed by using the ImageJ software. The darkening responses on film strips according to the doses were observed and they allowed obtaining the corresponding numeric values to the darkening for each specific dose value. From the numerical values of darkening, a calibration curve was obtained, which correlates the darkening of the film strip with dose values in mGy. The calibration curve equation is a simplified method for obtaining absorbed dose values using digital images of radiochromic films irradiated. With the calibration curve, radiochromic films may be applied on dosimetry in experiments on CT scans using X-ray beam of 120 kV, in order to improve CT acquisition image processes.

  6. Optical components of adaptive systems for improving laser beam quality

    Science.gov (United States)

    Malakhov, Yuri I.; Atuchin, Victor V.; Kudryashov, Aleksis V.; Starikov, Fedor A.

    2008-10-01

    The short overview is given of optical equipment developed within the ISTC activity for adaptive systems of new generation allowing for correction of high-power laser beams carrying optical vortices onto the phase surface. They are the kinoform many-level optical elements of new generation, namely, special spiral phase plates and ordered rasters of microlenses, i.e. lenslet arrays, as well as the wide-aperture Hartmann-Shack sensors and bimorph deformable piezoceramics- based mirrors with various grids of control elements.

  7. Comparison between TG-51 and TRS-398: electron contamination effect on photon beam-quality specification

    International Nuclear Information System (INIS)

    Medina, Antonio Lopez; Teijeiro, Antonio; Salvador, Francisco; Medal, Daniela; Vazquez, Julio; Salgado, Manuel; Carrion, MarIa C

    2004-01-01

    Two dosimetry protocols based on absorbed dose to water have recently been implemented: TG-51 and TRS-398. These protocols use different beam-quality indices. The effect of electron contamination in measurements of %dd(10) x has been proposed as a disadvantage of the TG-51. For actual measurements of %dd(10) x in five clinical beams ) a purging magnet was employed to remove the electron contamination. Also, %dd(10) x was measured in the different ways described in TG-51 for high-energy beams: with a lead foil at 50 cm from the phantom surface, at 30 cm, and for open beam. Moreover, TPR 20,10 was determined. Also, periodic quality-control measurements were used for comparing both quality indices and variation over time, but D 20,10 was used instead of TPR 20,10 and measurements in open beam for the %dd(10) x determination. Considering both protocols, S w,air and k Q were calculated in order to compare the results with the experimental data. Significant differences (0.3% for k Q ) were only found for the two high-energy beams, but when the electron contamination is underestimated by TG-51, the difference in k Q is lower. Differences in the other cases and variations over time were less than 0.1%

  8. Impact on quality culture of total quality management practices factors

    Directory of Open Access Journals (Sweden)

    Faihan Mosaad Saud Alotaibi

    2014-09-01

    Full Text Available This study investigated total quality management practices and quality culture of Saudi Arabian contractors. Improving the quality can be achieved through implementation of total quality management although studies and researches work regarding this improvement is still lacking. A quantitative approach using the survey method was employed. With assistance from the Saudi Arabia Ministry of Municipal and Rural Affairs, survey questionnaires were distributed to selected contractors in Saudi Arabia. The collected data were analysed using correlation, and multiple regression analyses. The key findings were the confirmation of significant relationships between all total quality management practices and quality culture and a positive relationship between quality management practices and quality culture. Furthermore, total quality management practices were found to be able to explain 68.1% of the variance in quality culture, while quality culture explained 12.5% of the variance in competitiveness. Quality culture was found to only partially mediate the relationship between total quality management practices and competitiveness.

  9. Clinical Ion Beam Applications: Basic Properties, Application, Quality Control, Planning

    International Nuclear Information System (INIS)

    Kraft, Gerhard

    2009-01-01

    Heavy-ion therapy using beam scanning and biological dose optimization is a novel technique of high-precision external radiotherapy. It yields a better perspective for tumor cure of radio-resistant tumors. However, heavy-ion therapy is not a general solution for all types of tumors. As compared to conventional radiotherapy, heavy-ion radiotherapy has the advantages of higher tumor dose, improved sparing of normal tissue in the entrance channel, a more precise concentration of the dose in the target volume with steeper gradients to the normal tissue, and a higher radiobiological effectiveness for tumors which are radio-resistant in conventional therapy. These properties make it possible to treat radio-resistant tumors with great success, including those in close vicinity to critical organs.

  10. Theoretical and numerical studies on the transport of transverse beam quality in plasma-based accelerators

    International Nuclear Information System (INIS)

    Mehrling, Timon Johannes

    2014-11-01

    This work examines effects, which impact the transverse quality of electron-beams in plasma-based accelerators, by means of theoretical and numerical methods. Plasma-based acceleration is a promising candidate for future particle accelerator technologies. In plasma-based acceleration, highly intense laser beams or high-current relativistic particle beams are focused into a plasma to excite plasma-waves with extreme transverse and longitudinal electric fields. The amplitude of these fields exceed with 10-100 GV/m the ones in today's radio-frequency accelerators by several orders of magnitude, hence, in principle allowing for accordingly shorter and cheaper accelerators based on plasma. Despite the tremendous progress in the recent decade, beams from plasma accelerators are not yet achieving the quality as demanded for pivotal applications of relativistic electron-beams, e.g. free-electron lasers (FELs).Studies within this work examine how the quality can be optimized in the production of the beams and preserved during the acceleration and transport to the interaction region. Such studies cannot be approached purely analytical but necessitate numerical methods, such as the Particle-In-Cell (PIC) method, which can model kinetic, electrodynamic and relativistic plasma phenomena. However, this method is computationally too expensive for parameter-scans in three-dimensional geometries. Hence, a quasi-static PIC code was developed in connection with this work, which is significantly more effective than the full PIC method for a class of problems in plasma-based acceleration.The evolution of the emittance of beams which are injected into plasma modules was studied in this work by means of theoretical and the above numerical methods. It was shown that the beam parameters need to be matched accurately into the focusing plasma-channel in order to allow for beam-quality preservation. This suggested that new extraction and injection-techniques are required in staged plasma

  11. Metrology and quality of radiation therapy dosimetry of electron, photon and epithermal neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Kosunen, A

    1999-08-01

    In radiation therapy using electron and photon beams the dosimetry chain consists of several sequential phases starting by the realisation of the dose quantity in the Primary Standard Dosimetry Laboratory and ending to the calculation of the dose to a patient. A similar procedure can be described for the dosimetry of epithermal neutron beams in boron neutron capture therapy (BNCT). To achieve the required accuracy of the dose delivered to a patient the quality of all steps in the dosimetry procedure has to be considered. This work is focused on two items in the dosimetry chains: the determination of the dose in the reference conditions and the evaluation of the accuracy of dose calculation methods. The issues investigated and discussed in detail are: a)the calibration methods of plane parallel ionisation chambers used in electron beam dosimetry, (b) the specification of the critical dosimetric parameter i.e. the ratio of stopping powers for water to air, (S I ?){sup water} {sub air}, in photon beams, (c) the feasibility of the twin ionization chamber technique for dosimetry in epithermal neutron beams applied to BNCT and (d) the determination accuracy of the calculated dose distributions in phantoms in electron, photon, and epithermal neutron beams. The results demonstrate that up to a 3% improvement in the consistency of dose determinations in electron beams is achieved by the calibration of plane parallel ionisation chambers in high energy electron beams instead of calibrations in {sup 60}Co gamma beams. In photon beam dosimetry (S I ?){sup water} {sub air} can be determined with an accuracy of 0.2% using the percentage dose at the 10 cm depth, %dd(10), as a beam specifier. The use of %odd(10) requires the elimination of the electron contamination in the photon beam. By a twin ionisation chamber technique the gamma dose can be determined with uncertainty of 6% (1 standard deviation) and the total neutron dose with an uncertainty of 15 to 20% (1 standard deviation

  12. Metrology and quality of radiation therapy dosimetry of electron, photon and epithermal neutron beams

    International Nuclear Information System (INIS)

    Kosunen, A.

    1999-08-01

    In radiation therapy using electron and photon beams the dosimetry chain consists of several sequential phases starting by the realisation of the dose quantity in the Primary Standard Dosimetry Laboratory and ending to the calculation of the dose to a patient. A similar procedure can be described for the dosimetry of epithermal neutron beams in boron neutron capture therapy (BNCT). To achieve the required accuracy of the dose delivered to a patient the quality of all steps in the dosimetry procedure has to be considered. This work is focused on two items in the dosimetry chains: the determination of the dose in the reference conditions and the evaluation of the accuracy of dose calculation methods. The issues investigated and discussed in detail are: a)the calibration methods of plane parallel ionisation chambers used in electron beam dosimetry, (b) the specification of the critical dosimetric parameter i.e. the ratio of stopping powers for water to air, (S I ?) water air , in photon beams, (c) the feasibility of the twin ionization chamber technique for dosimetry in epithermal neutron beams applied to BNCT and (d) the determination accuracy of the calculated dose distributions in phantoms in electron, photon, and epithermal neutron beams. The results demonstrate that up to a 3% improvement in the consistency of dose determinations in electron beams is achieved by the calibration of plane parallel ionisation chambers in high energy electron beams instead of calibrations in 60 Co gamma beams. In photon beam dosimetry (S I ?) water air can be determined with an accuracy of 0.2% using the percentage dose at the 10 cm depth, %dd(10), as a beam specifier. The use of %odd(10) requires the elimination of the electron contamination in the photon beam. By a twin ionisation chamber technique the gamma dose can be determined with uncertainty of 6% (1 standard deviation) and the total neutron dose with an uncertainty of 15 to 20% (1 standard deviation). To improve the accuracy

  13. Absorbed dose calibration factors for parallel-plate chambers in high energy photon beams

    International Nuclear Information System (INIS)

    McEwen, M.R.; Duane, S.; Thomas, R.A.S.

    2002-01-01

    parallel-plate chambers, which is discussed below. The small difference (around 0.3%) between the NACP and Roos chambers at the highest photon energies is within the measurement uncertainties but may indicate a slight difference in chamber response. A number of chambers were recalibrated six months later to investigate chamber stability. It was found that the repeatability was generally better than 0.5% and the variations in time appear to be random. These differences are larger than for thimble chambers, where we have found stability at better than the 0.3% level over several years. Parallel-plate chambers in electron beams have also showed high stability (McEwen et al, 2001), which would indicate that parallel-plate chambers are sensitive to small variations in the beam quality of photon beams that do not affect thimble chambers. This data can also be used to derive relative wall correction factors for the Roos and NACP. Good agreement (within 0.3%) was found with previous data (Palm et al, 2000; Nystrom et al, 1993). These measurements would seem to confirm that p wall for the Roos chamber given in TRS-381 is too low by around 0.5%. Parallel-plate chambers can be calibrated in terms of absorbed dose to water, but with an uncertainty larger than for thimble chambers. Chamber stability also appears to be worse than for thimble chambers. Polarity corrections must always be measured and applied, as the polarity effect for a particular chamber is difficult to predict

  14. Focused ion-beam line profiles: A study of some factors affecting beam broadening

    International Nuclear Information System (INIS)

    Templeton, I.M.; Champion, H.G.

    1995-01-01

    The current--density profile of a focused ion beam (FIB) has a central peak accompanied by broader ''wings'' that, while unimportant in lithographic applications, can lead to unwanted effects during an implantation operation. The origin of the wings, and hence the best way to minimize them, is not clear and needs further study. We have measured the line profiles of several of the ions available in our FIB machine as a function of a number of variables, under ultrahigh vacuum (UHV) conditions. No effects are observed from changes in emission current or deliberate defocusing of the objective lens. There are some changes with beam aperture and/or current, but the biggest differences seem to be associated with a change of source type and hence, possibly, with a change in the source/extractor configuration or in the alloy and the emission process. The wing amplitudes are appreciably lower than many previously observed, and their profiles, at least for the lighter ions studied (Be ++ , Be + , and B + ), are Gaussian rather than exponential. It seems possible that our UHV conditions may have eliminated a scattering mechanism responsible for the larger, exponential wings previously observed. The corresponding beam and rectangle-edge profiles have been calculated. copyright 1995 American Vacuum Society

  15. Quality assurance of computed tomography scanner beams in diagnostic radiology

    International Nuclear Information System (INIS)

    Lindskoug, B.A.

    1989-01-01

    The number of computed tomography (CT) scanners in diagnostic radiology is increasing, to the extent that they are now found in relatively small hospitals. These hospitals do not have local physicists available and so methods must be developed to allow quality assurance to be carried out at distant laboratories. Several different types of solid water phantoms are available with various built-in test objects that may supply sufficient information about the many parameters that must be checked. The dose distributions, however, are usually not so well considered, although the connection between image quality and absorbed dose must be known for optimal use of a CT scanner. By introducing thermoluminescent dosemeters (TLDs) into a commercial phantom (RMI), it was possible to measure the absorbed dose profile and the line integral of the absorbed dose across the slit. The computer-guided readout of the TLDs gives the absorbed dose, the average dose and half maximum width, absorbed dose curve, and also the line integral of the peak. The only modification of the phantom was five holes, drilled at strategic positions, that did not influence the built-in test objects. This single measurement provides an appropriate monthly quality assurance check of the CT scanner with little extra effort. (author)

  16. Novel imaging and quality assurance techniques for ion beam therapy a Monte Carlo study

    CERN Document Server

    Rinaldi, I; Jäkel, O; Mairani, A; Parodi, K

    2010-01-01

    Ion beams exhibit a finite and well defined range in matter together with an “inverted” depth-dose profile, the so-called Bragg peak. These favourable physical properties may enable superior tumour-dose conformality for high precision radiation therapy. On the other hand, they introduce the issue of sensitivity to range uncertainties in ion beam therapy. Although these uncertainties are typically taken into account when planning the treatment, correct delivery of the intended ion beam range has to be assured to prevent undesired underdosage of the tumour or overdosage of critical structures outside the target volume. Therefore, it is necessary to define dedicated Quality Assurance procedures to enable in-vivo range verification before or during therapeutic irradiation. For these purposes, Monte Carlo transport codes are very useful tools to support the development of novel imaging modalities for ion beam therapy. In the present work, we present calculations performed with the FLUKA Monte Carlo code and pr...

  17. Biophysics of NASA radiation quality factors

    International Nuclear Information System (INIS)

    Cucinotta, Francis A.

    2015-01-01

    NASA has implemented new radiation quality factors (QFs) for projecting cancer risks from space radiation exposures to astronauts. The NASA QFs are based on particle track structure concepts with parameters derived from available radiobiology data, and NASA introduces distinct QFs for solid cancer and leukaemia risk estimates. The NASA model was reviewed by the US National Research Council and approved for use by NASA for risk assessment for International Space Station missions and trade studies of future exploration missions to Mars and other destinations. A key feature of the NASA QFs is to represent the uncertainty in the QF assessments and evaluate the importance of the QF uncertainty to overall uncertainties in cancer risk projections. In this article, the biophysical basis for the probability distribution functions representing QF uncertainties was reviewed, and approaches needed to reduce uncertainties were discussed. (author)

  18. Biophysics of NASA radiation quality factors.

    Science.gov (United States)

    Cucinotta, Francis A

    2015-09-01

    NASA has implemented new radiation quality factors (QFs) for projecting cancer risks from space radiation exposures to astronauts. The NASA QFs are based on particle track structure concepts with parameters derived from available radiobiology data, and NASA introduces distinct QFs for solid cancer and leukaemia risk estimates. The NASA model was reviewed by the US National Research Council and approved for use by NASA for risk assessment for International Space Station missions and trade studies of future exploration missions to Mars and other destinations. A key feature of the NASA QFs is to represent the uncertainty in the QF assessments and evaluate the importance of the QF uncertainty to overall uncertainties in cancer risk projections. In this article, the biophysical basis for the probability distribution functions representing QF uncertainties was reviewed, and approaches needed to reduce uncertainties were discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. CALiPER Report 20.1: Subjective Evaluation of Beam Quality, Shadow Quality, and Color Quality for LED PAR38 Lamps

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2013-11-07

    This report focuses on human-evaluated characteristics, including beam quality, shadow quality, and color quality. Using a questionnaire that included rank-ordering, opinions on 27 of the Report 20 PAR38 lamps were gathered during a demonstration event for members of the local Illuminating Engineering Society (IES) chapter. This was not a rigorous scientific experiment, and the data should not be extrapolated beyond the scope of the demonstration. The results suggest that many of the LED products compared favorably to halogen PAR38 benchmarks in all attributes considered. LED lamps using a single-emitter design were generally preferred for their beam quality and shadow quality, and the IES members' ranking of color quality did not always match the rank according to the color rendering index (CRI).

  20. DOE CALiPER Program, Report 20.1 Subjective Evaluation of Beam Quality, Shadow Quality, and Color Quality for LED PAR38 Lamps

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Poplawski, Michael E.; Miller, Naomi J.

    2013-10-01

    This report focuses on human-evaluated characteristics, including beam quality, shadow quality, and color quality. Using a questionnaire that included rank ordering, opinions on 27 of the Report 20 PAR38 lamps were gathered during a demonstration event for members of the local Illuminating Engineering Society (IES) chapter. This was not a rigorous scientific experiment, and the data should not be extrapolated beyond the scope of the demonstration. The results suggest that many of the LED products compared favorably to halogen PAR38 benchmarks in all attributes considered. LED lamps using a single-emitter design were generally preferred for their beam quality and shadow quality, and the IES members ranking of color quality did not always match the rank according to the color rendering index (CRI).

  1. Investigating the effect of electron emission pattern on RF gun beam quality

    Energy Technology Data Exchange (ETDEWEB)

    Rajabi, A. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Shokri, B., E-mail: b-shokri@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Velenjak, 1983963113, Tehran (Iran, Islamic Republic of)

    2016-05-11

    Thermionic radio frequency gun is one of the most promising choices to gain a high quality electron beam, used in the infrared free electron lasers and synchrotron radiation injectors. To study the quality of the beam in a compact electron source, the emission pattern effect on the beam dynamics should be investigated. In the presented work, we developed a 3D simulation code to model the real process of thermionic emission and to investigate the effect of emission pattern, by considering geometrical constraints, on the beam dynamics. According to the results, the electron bunch emittance varies considerably with the emission pattern. Simulation results have been validated via comparison with the well-known simulation codes such as ASTRA simulation code and CST microwave studio, as well as other simulation results in the literature. It was also demonstrated that by using a continuous wave laser beam for heating the cathode, the emission pattern full width at half maximum (FWHM) of the transverse emission distribution is proportional to FWHM of the Gaussian profile for the laser beam. Additionally, by using the developed code, the effect of wall structure around the cathode on the back bombardment effect has been studied. According to the results, for a stable operation of the RF gun, one should consider the nose cone in vicinity of the cathode surface to reduce the back-bombardment effect. - Highlights: • We developed a 3D code to simulate the beam dynamics of thermionic RF gun. • Te impact of the emission pattern on the beam dynamic was investigated. • Different emission pattern results different emittance in the gun exit. • Using a nosecone around the cathode adjacent wall reduces back bombardment effect.

  2. Practical use of a plastic scintillator for quality assurance of electron beam therapy.

    Science.gov (United States)

    Yogo, Katsunori; Tatsuno, Yuya; Tsuneda, Masato; Aono, Yuki; Mochizuki, Daiki; Fujisawa, Yoshiki; Matsushita, Akihiro; Ishigami, Minoru; Ishiyama, Hiromichi; Hayakawa, Kazushige

    2017-06-07

    Quality assurance (QA) of clinical electron beams is essential for performing accurate and safe radiation therapy. However, with advances in radiation therapy, QA has become increasingly labor-intensive and time-consuming. In this paper, we propose a tissue-equivalent plastic scintillator for quick and easy QA of clinical electron beams. The proposed tool comprises a plastic scintillator plate and a charge-coupled device camera that enable the scintillation light by electron beams to be recorded with high sensitivity and high spatial resolution. Further, the Cerenkov image is directly subtracted from the scintillation image to discriminate Cerenkov emissions and accurately measure the dose profiles of electron beams with high spatial resolution. Compared with conventional methods, discrepancies in the depth profile improved from 7% to 2% in the buildup region via subtractive corrections. Further, the output brightness showed good linearity with dose, good reproducibility (deviations below 1%), and dose rate independence (within 0.5%). The depth of 50% dose measured with the tool, an index of electron beam quality, was within  ±0.5 mm of that obtained with an ionization chamber. Lateral brightness profiles agreed with the lateral dose profiles to within 4% and no significant improvement was obtained using Cerenkov corrections. Field size agreed to within 0.5 mm with those obtained with ionization chamber. For clinical QA of electron boost treatment, a disk scintillator that mimics the shape of a patient's breast is applied. The brightness distribution and dose, calculated using a treatment planning system, was generally acceptable for clinical use, except in limited zones. Overall, the proposed plastic scintillator plate tool efficiently performs QA for electron beam therapy and enables simultaneous verification of output constancy, beam quality, depth, and lateral dose profiles during monthly QAs at lower doses of irradiation (small monitor units, MUs).

  3. Long-term stability of beam quality and output of conventional X-ray units

    OpenAIRE

    Fukuda, Atsushi; Matsubara, Kosuke; Miyati, Toshiaki

    2015-01-01

    Conventional diagnostic X-ray units are used for radiographic imaging in many countries. For obtaining entrance surface doses, a numerical dose determination method has been applied in Japan. Although this technique is effective, it has to account for errors, particularly fluctuations, due to the beam quality and output of X-ray tubes. As a part of our quality control procedures, we recorded the entrance surface air kerma, tube voltage, and half-value layer measurements made for four diagnost...

  4. Commissioning and quality assurances of the CMS XIO radiotherapy treatment planning system for external beam photons

    International Nuclear Information System (INIS)

    Muralidhar, K.R.; Anurupa; Soubhagya; Sudhakar; Shiva; Krishnam Raju, A.; Narayana Murthy, P.

    2008-01-01

    The commissioning of XIO treatment planning system (TPS) was carried out by Computerized Medical Devices, USA for Siemens and Elekta linear accelerators. The Commissioning and quality assurance of the CMS XIO radiotherapy treatment planning system involves many steps, beginning from beam data acquisition and entry into the computerized TPS, through patient data acquisition, to treatment plan generation and the final transfer of data to the treatment machine and quality assurance of TPS

  5. Beam quality management by periodic reproduction of wavefront aberrations in end-pumped Nd:YVO4 laser amplifiers.

    Science.gov (United States)

    Liu, Bin; Liu, Chong; Shen, Lifeng; Wang, Chunhua; Ye, Zhibin; Liu, Dong; Xiang, Zhen

    2016-04-18

    A method for beam quality management is presented in a master oscillator power amplifier (MOPA) using Nd:YVO4 as the gain medium by extra-cavity periodic reproduction of wavefront aberrations. The wavefront aberration evolution of the intra-cavity beams is investigated for both symmetrical and asymmetrical resonators. The wavefront aberration reproduction process is successfully realized outside the cavity in four-stage amplifiers. In the MOPA with a symmetrical oscillator, the laser power increases linearly and the beam quality hardly changes. In the MOPA with an asymmetrical oscillator, the beam quality is deteriorated after the odd-stage amplifier and is improved after the even-stage amplifier. The wavefront aberration reproduction during the extra-cavity beam propagation in the amplifiers is equivalent to that during the intra-cavity propagation. This solution helps to achieve the effective beam quality management in laser amplifier chains.

  6. Accurate model of photon beams as a tool for commissioning and quality assurance of treatment planning calculations

    International Nuclear Information System (INIS)

    Linares Rosales, Haydee M.; Lara Mas, Elier; Alfonso Laguardia, Rodolfo

    2015-01-01

    Simulation of a linear accelerator (linac) head requires determining the parameters that characterize the primary electron beam striking on the target which is a step that plays a vital role in the accuracy of Monte Carlo calculations. In this work, the commissioning of photon beams (6 MV and 15 MV) of an Elekta Precise accelerator, using the Monte Carlo code EGSnrc, was performed. The influence of the primary electron beam characteristics on the absorbed dose distribution for two photon qualities was studied. Using different combinations of mean energy and radial FWHM of the primary electron beam, deposited doses were calculated in a water phantom, for different field sizes. Based on the deposited dose in the phantom, depth dose curves and lateral dose profiles were constructed and compared with experimental values measured in an arrangement similar to the simulation. Taking into account the main differences between calculations and measurements, an acceptability criteria based on confidence limits was implemented. As expected, the lateral dose profiles for small field sizes were strongly influenced by the radial distribution (FWHM). The combinations of energy/FWHM that best reproduced the experimental results were used to generate the phase spaces, in order to obtain a model with the motorized wedge included and to calculate output factors. A good agreement was obtained between simulations and measurements for a wide range of fi eld sizes, being all the results found within the range of tolerance. (author)

  7. 2000W high beam quality diode laser for direct materials processing

    Science.gov (United States)

    Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

    2011-11-01

    This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

  8. Improved image quality for asymmetric double-focal cone-beam SPECT

    International Nuclear Information System (INIS)

    Cao, Z.J.; Tsui, B.M.W.

    1993-01-01

    To optimize both spatial resolution and detection efficiency in brain SPECT imaging using a rectangular camera, an asymmetric double-focal cone-beam collimator is proposed with the focal points located near the base plane of the patient's head. To fit the entire head into the field-of-view of the collimator with dimensions of 50cmx40cm and at a radius-of-rotation of 15 cm, the focal lengths of the collimator are 55 and 70 cm, respectively, in the transverse and axial directions. With this geometry, the artifacts in the reconstructed image produced by the Feldkamp algorithm are more severe compared to those in a symmetric cone-beam geometry, due to the larger vertex angle between the top of the head and the base plane. To improve the reconstructed image quality, a fully three-dimensional (3D) reconstruction algorithm developed previously for single-focal cone-beam SPECT was extended to the asymmetric double-focal cone-beam geometry. The algorithm involves nonstationary 2D filtering and a reprojection technique for estimation of the missing data caused by a single-orbit cone-beam geometry. The results from simulation studies with the 3D Defrise slab phantom demonstrated that the fully 3D algorithm provided a much improved image quality in terms of reduced slice-to-slice cross talks and shape elongation compared to that produced by the conventional Feldkamp algorithm

  9. Quality of 'Climax' blueberries after low dosage electron beam irradiation

    International Nuclear Information System (INIS)

    Miller, W.R.; McDonald, R.E.; McCollum, T.G.; Smittle, B.J.

    1994-01-01

    Fruit of 'Climax' rabbiteye blueberries (Vaccinium ashei Reade) were irradiated by a linear accelerator at 0, 0.25, 0.5, 0.75, 1.0, and 1.25 kGy and evaluated for various quality attributes after storage for 1, 3, 7, or 14 days at 1C plus 2 days at 15C, respectively. Weight loss increased during storage and averaged 4.2% after the final inspection and was not affected by irradiation dosage. About 5% of total berries were decayed after 14 days at 1C, about 6% after the final inspection at 15C, but decay was not affected by the level of irradiation. Electrolyte leakage, skin color, total soluble solids, acidity, and pH were also not affected by irradiation dosage. There was a significant decline in berry firmness, flavor, and texture as dosage increased. Berries treated at 1.0 kGy or above were softer and had lower flavor and texture preference scores than berries treated at lower dosages or nontreated berries

  10. Use of a two-dimensional ionization chamber array for proton therapy beam quality assurance

    International Nuclear Information System (INIS)

    Arjomandy, Bijan; Sahoo, Narayan; Ding Xiaoning; Gillin, Michael

    2008-01-01

    Two-dimensional ion chamber arrays are primarily used for conventional and intensity modulated radiotherapy quality assurance. There is no commercial device of such type available on the market that is offered for proton therapy quality assurance. We have investigated suitability of the MatriXX, a commercial two-dimensional ion chamber array detector for proton therapy QA. This device is designed to be used for photon and electron therapy QA. The device is equipped with 32x32 parallel plate ion chambers, each with 4.5 mm diam and 7.62 mm center-to-center separation. A 250 MeV proton beam was used to calibrate the dose measured by this device. The water equivalent thickness of the buildup material was determined to be 3.9 mm using a 160 MeV proton beam. Proton beams of different energies were used to measure the reproducibility of dose output and to evaluate the consistency in the beam flatness and symmetry measured by MatriXX. The output measurement results were compared with the clinical commissioning beam data that were obtained using a 0.6 cc Farmer chamber. The agreement was consistently found to be within 1%. The profiles were compared with film dosimetry and also with ion chamber data in water with an excellent agreement. The device is found to be well suited for quality assurance of proton therapy beams. It provides fast two-dimensional dose distribution information in real time with the accuracy comparable to that of ion chamber measurements and film dosimetry

  11. Response of TLD-100"T"M microtubes to two RQR3 quality radiation beams

    International Nuclear Information System (INIS)

    Nunes, M.G.; Villani, D.; Almeida, S.B.; Vivolo, V.; Yoriyaz, H.; Louis, G.M.J.

    2016-01-01

    The present work compares the response of TLD-100"T"M microcubes to two RQR 3 diagnostic radiology reference quality radiation beams, defined by IEC-61267 norm, aiming to evaluate the detectability of TLD-100"T"M energy dependence reported in literature within the same reference quality radiation range. TLD-100"T"M microcubes reproducibility is assessed through the response of a second set of TLD-100"T"M microcubes, evaluated in a second thermoluminescence reader, to the RQR 3 diagnostic radiology reference quality radiation beam implemented at the Laboratorio de Calibracao de Instrumentos of IPEN, Sao Paulo, SP, Brazil. The dependence of TLD-100"T"M microcubes TL response was not detectable in these conditions and the reproducibility of the measurements is 90,2%. (author)

  12. Surface water quality assessment using factor analysis

    African Journals Online (AJOL)

    2006-01-16

    Jan 16, 2006 ... Surface water, groundwater quality assessment and environ- .... Urbanisation influences the water cycle through changes in flow and water ..... tion of aquatic life, CCME water quality Index 1, 0. User`s ... Water, Air Soil Pollut.

  13. Measurement of conversion coefficients between air Kerma and personal dose equivalent and backscatter factors for diagnostic X-ray beams

    International Nuclear Information System (INIS)

    Rosado, Paulo Henrique Goncalves

    2008-01-01

    Two sets of quantities are import in radiological protection: the protection and operational quantities. Both sets can be related to basic physical quantities such as kerma through conversion coefficients. For diagnostic x-ray beams the conversion coefficients and backscatter factors have not been determined yet, those parameters are need for calibrating dosimeters that will be used to determine the personal dose equivalent or the entrance skin dose. Conversion coefficients between air kerma and personal dose equivalent and backscatter factors were experimentally determined for the diagnostic x-ray qualities RQR and RQA recommended by the International Electrotechnical Commission (IEC). The air kerma in the phantom and the mean energy of the spectrum were measured for such purpose. Harshaw LiF-100H thermoluminescent dosemeters (TLD) were used for measurements after being calibrated against an 180 cm 3 Radcal Corporation ionization chamber traceable to a reference laboratory. A 300 mm x 300 mm x 150 mm polymethylmethacrylate (PMMA) slab phantom was used for deep-dose measurements. Tl dosemeters were placed in the central axis of the x-ray beam at 5, 10, 15, 25 and 35 mm depth in the phantom upstream the beam direction Another required parameter for determining the conversion coefficients from was the mean energy of the x-ray spectrum. The spectroscopy of x-ray beams was done with a CdTe semiconductor detector that was calibrated with 133 Ba, 241 Am and 57 Co radiation sources. Measurements of the x-ray spectra were carried out for all RQR and RQA IEC qualities. Corrections due to the detector intrinsic efficiency, total energy absorption, escape fraction of the characteristic x-rays, Compton effect and attenuation in the detector were done aiming an the accurate determination of the mean energy. Measured x-ray spectra were corrected with the stripping method by using these response functions. The typical combined standard uncertainties of conversion coefficients and

  14. Influence of beam divergence on form-factor in X-ray diffraction radiation

    International Nuclear Information System (INIS)

    Sergeeva, D.Yu.; Tishchenko, A.A.; Strikhanov, M.N.

    2015-01-01

    Diffraction radiation from divergent beam is considered in terms of radiation in UV and X-ray range. Scedastic form of Gaussian distribution of the particle in the bunch, i.e. Gaussian distribution with changing dispersion has been used, which is more adequate for description of divergent beams than often used Gaussian distribution with constant dispersion. Both coherent and incoherent form-factors are taken into account. The conical diffraction effect in diffraction radiation is proved to make essential contribution in spectral-angular characteristics of radiation from a divergent beam

  15. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Moteabbed, Maryam, E-mail: mmoteabbed@partners.org; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-05-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D{sub mean}) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D{sub mean} and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D{sub mean} and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  16. Pilot Quality Control Program for Audit RT External Beams at Mexican Hospitals

    International Nuclear Information System (INIS)

    Alvarez R, J T; Tovar M, V M

    2008-01-01

    A pilot quality control program for audit 18 radiotherapy RT external beams at 13 Mexican hospitals is described--for eleven 60 Co beams and seven photon beams of 6, 10 and 15 MV from accelerators. This program contains five parts: a) Preparation of the TLD-100 powder: washing, drying and annealing (one hour 400 deg. C plus 24 hrs 80 deg. C). b) Sending two IAEA type capsules to the hospitals for irradiation at the hospital to a nominal D W = 2 Gy·c) Preparation at the SSDL of ten calibration curves CC in the range of 0.5 Gy to 6 Gy in terms of absorbed dose to water D W for 60 Co with traceability to primary laboratory NRC (Canada), according to a window irradiation: 26/10/2007-7/12/2007. d) Reading all capsules that match their hospital time irradiation and the SSDL window irradiation. f) Evaluation of the Dw imparted by the hospitals

  17. Pilot Quality Control Program for Audit RT External Beams at Mexican Hospitals

    Science.gov (United States)

    Álvarez R., J. T.; Tovar M., V. M.

    2008-08-01

    A pilot quality control program for audit 18 radiotherapy RT external beams at 13 Mexican hospitals is described—for eleven 60 Co beams and seven photon beams of 6, 10 and 15 MV from accelerators. This program contains five parts: a) Preparation of the TLD-100 powder: washing, drying and annealing (one hour 400 °C plus 24 hrs 80 °C). b) Sending two IAEA type capsules to the hospitals for irradiation at the hospital to a nominal DW = 2 Gy ṡ c ) Preparation at the SSDL of ten calibration curves CC in the range of 0.5 Gy to 6 Gy in terms of absorbed dose to water DW for 60 Co with traceability to primary laboratory NRC (Canada), according to a window irradiation: 26/10/2007-7/12/2007. d) Reading all capsules that match their hospital time irradiation and the SSDL window irradiation. f) Evaluation of the Dw imparted by the hospitals.

  18. Effect of area x-ray beam equalization on image quality and dose in digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Jerry; Xu Tong; Husain, Adeel; Le, Huy; Molloi, Sabee [Department of Radiological Sciences, University of California, Irvine, CA 92697 (United States)

    2004-08-21

    In mammography, thick or dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing the x-ray exposure to under-penetrated regions without increasing the exposure to other breast regions. Optimal equalization parameters with respect to image quality and patient dose were determined through computer simulations and validated with experimental observations on a step phantom and an anthropomorphic breast phantom. Three parameters important in equalization digital mammography were considered: attenuator material (Z = 13-92), beam energy (22-34 kVp) and equalization level. A Mo/Mo digital mammography system was used for image acquisition. A prototype 16 x 16 piston driven equalization system was used for preparing patient-specific equalization masks. Simulation studies showed that a molybdenum attenuator and an equalization level of 20 were optimal for improving contrast, CNR and figure of merit (FOM = CNR{sup 2}/dose). Experimental measurements using these parameters showed significant improvements in contrast, CNR and FOM. Moreover, equalized images of a breast phantom showed improved image quality. These results indicate that area beam equalization can improve image quality in digital mammography.

  19. ISTC Projects from RFNC-VNIIEF Devoted to Improving Laser Beam Quality

    Science.gov (United States)

    Starikov, F.; Kochemasov, G.

    Information is given about the Projects # 1929 and # 2631 supported by ISTC and concerned with improving laser beam quality and interesting for adaptive optics community. One of them, Project # 1929 has been recently finished. It has been devoted to development of an SBS phase conjugation mirror of superhigh conjugation quality employing the kinoform optics for high-power lasers with nanosecond scale pulse duration. With the purpose of reaching ideal PC fidelity, the SBS mirror includes the raster of small lenses that has been traditionally used as the lenslet in Shack-Hartmann wavefront sensor in adaptive optics. The second of them, Project # 2631, is concerned with the development of an adaptive optical system for phase correction of laser beams with wavefront vortex. The principles of operation of modern adaptive systems are based on the assumption that the phase is a smooth continuous function in space. Therefore the solution of the Project tasks will assume a new step in adaptive optics.

  20. ATLAS tile calorimeter data quality assessment and performance with calibration, cosmic and first beam data

    International Nuclear Information System (INIS)

    Volpi, Matteo

    2010-01-01

    The commissioning of the barrel hadronic calorimeter (Tile) of the ATLAS detector at the Large Hadron Collider (LHC) has been the focus of an extensive project over the last several years. Work with Tile has resulted in a fully operational detector before the first LHC beam test on 10 September 2008. A set of tools has been developed spanning from the hardware and software systems of the detector and online monitoring to the offline reconstruction. This set of tools constitutes the final Tile data quality system and is highly integrated with all ATLAS online and offline frameworks. A review of the final data quality system of the Tile hadronic calorimeter will be presented together with selected results on hardware reliability. This will be followed by the detector performance checks performed on cosmic data and on the first LHC beam data taken on 10 September 2008.

  1. Impact of coherent synchrotron radiation on beam qualities in a Chicane

    International Nuclear Information System (INIS)

    Xiang Dao; Huang Wenhui; He Xiaozhong

    2004-01-01

    When the bunch goes through a Chicane, the energy will be redistributed within the bunch due to CSR (coherent synchrotron radiation), which would cause nonlinearity. Present theory states that this nonlinearity would add a huge amount to emittance growth. Based on simulation results, this paper would point out that the theory is only valid under an ideal condition that the bunch initially has no nonlinearity and under some given parameters there could be a cancellation between the nonlinearity caused by CSR and the initial nonlinearity. So under these circumstances authors can expect CSR to improve the beam quality. This paper provides a brief information about CSR and a full estimation of effects of CSR on beam qualities

  2. Quality factor improvement of silicon nitride micro string resonators

    DEFF Research Database (Denmark)

    Schmid, Silvan; Malm, Bjarke; Boisen, Anja

    2011-01-01

    Resonant micro and nano strings are of interest for sensor applications due to their extraordinary high quality factors, low mass and tunable resonant frequency. It has been found that the quality factor of strings is usually limited by clamping loss. In this work, clamping loss has been addressed...... by varying the clamping design and string geometry. We present silicon nitride micro strings with quality factors (Q) of up to 4 million in high vacuum achieved by minimizing clamping loss. For applications such as for chemical sensing, strings need to vibrate at atmospheric pressure. Maximal quality factor...

  3. Elimination of importance factors for clinically accurate selection of beam orientations, beam weights and wedge angles in conformal radiation therapy

    International Nuclear Information System (INIS)

    Bedford, James L.; Webb, Steve

    2003-01-01

    A method of simultaneously optimizing beam orientations, beam weights, and wedge angles for conformal radiotherapy is presented. This method removes the need for importance factors by optimizing one objective only, subject to a set of rigid constraints. This facilitates the production of inverse solutions which, without trial-and-error modification of importance factors, precisely satisfy the specified constraints. The algorithm minimizes an objective function which is based upon the single objective to be optimized, but which is forced to an artificially high value when the constraints are not met, so that only satisfactory solutions are allowed. Due to the complex nature of the objective function space, including multiple local minima separated by large regions of plateau, a random search technique equivalent to fast simulated annealing is used for producing inverse plans. To illustrate the novel features of the new algorithm, a simulation is first presented, for the case of a cylindrical phantom. The morphology of the objective function space is shown to be significantly different for the new algorithm, compared to that for a conventional quadratic objective function. Clinical cases for prostate and craniopharyngioma are then presented. For the prostate case, the objective is to reduce irradiated rectal volume. Three-field, four-field, and six-field optimizations, with or without orientation optimization, are shown to provide solutions which are consistent with previously reported plans and class solutions. For the craniopharyngioma case, which involves the use of a high-precision stereotactic conformal technique, the objective is to reduce the irradiated volume of normal brain. Practically feasible beam angles are produced which, compared to a standard plan, provide a small but worthwhile sparing of normal brain. The algorithm is thereby shown to be robust and suitable for clinical application

  4. Project outline of high quality electron beam generation at Waseda University

    Energy Technology Data Exchange (ETDEWEB)

    Washio, M.; Hama, Y.; Kashiwagi, S.; Kuroda, R.; Kobuki, T. [Waseda Univ., Advanced Research Institute for Science and Engineering, Shinjuku, Tokyo (Japan); Hirose, T. [Tokyo Metropolitan Univ. (Japan). Dept. of Physics

    2000-03-01

    High quality electron beam generation project has been started at Waseda University under the grant of Ministry of Education, named High-Tech Research Center Project. In the project, we will install a laser photo-cathode RF Gun system with 1.6 accelerating structure cells of s-band and a stabilized RF power source. This RF Gun is expected to produce single electron bunch up to 1 or 2nC with around 10ps pulse duration. (author)

  5. Project outline of high quality electron beam generation at Waseda University

    International Nuclear Information System (INIS)

    Washio, M.; Hama, Y.; Kashiwagi, S.; Kuroda, R.; Kobuki, T.; Hirose, T.

    2000-01-01

    High quality electron beam generation project has been started at Waseda University under the grant of Ministry of Education, named High-Tech Research Center Project. In the project, we will install a laser photo-cathode RF Gun system with 1.6 accelerating structure cells of s-band and a stabilized RF power source. This RF Gun is expected to produce single electron bunch up to 1 or 2nC with around 10ps pulse duration. (author)

  6. Two-cascade push-pull synchrotron with 100% time duty factor of extracted beam

    International Nuclear Information System (INIS)

    Karabekov, I.P.

    1987-01-01

    Schemes of producing beams of electrons and gamma-quanta in energy range of several GeV using synchroton accelerating principle is suggested. Results of calculating basic parameters of suggested accelerator for 6 GeV energy and 40 μA current which prove the idea of its construction are presented. Two sections of particle input and impinge have been created in the accelerator. Particles in the ring are twice accelerated during the oscillation period of feed electromagnet variable component in opposite directions of orbit circulation. Extracted beam axes intersect in some point of the orbit plane. The mixing magnetic field, directing both beams along the common trajectory to the target is established in this point. In order to achieve 100% beam duty factor it is suggested to use the scheme of combining two magnetic tracks in electromagnet with fluxes, characterized by Π/2 phase shift

  7. Quality control and radioprotection in dental cone beam computed tomography - case study

    International Nuclear Information System (INIS)

    Rodrigues, Ligiane C.N.; Ferreira, Nadya M.P.D.

    2011-01-01

    The radiological protection in medical and odontologic radiology follows The Order (Portaria) 453/98 of the Ministry of Health, which presents the minimum set of tests for the constancy X-ray equipment. These tests follow the procedures set forth in the Resolution no. 64, the National Agency for Sanitary Vigilance. This work aims to show a study on dental cone beam computed tomography (CBCT), evaluating the physical parameters that influence the performance and image quality and presenting the appropriate tests to this new system. The authors analyzed the tests specific for computed tomography (CT) of the Resolution no. 64, feasibility assessment of them and if their interpretations are compatible with CBCT. Once determined if testing is feasible, compare with those presented in the manual provided by the equipment manufacturer. The CT scanner used was the Mini-Cat Tomography Scanner Xoran Technologies of KAVO. In the study it was verified that four tests could be reproduced in CBCT: noise, accuracy and uniformity in the number of CT of water and spatial resolution. Considering experimental data, the methodology and tolerance of manufacturer for the first two tests were more appropriate. For the uniformity test of the CT number, we recommend using the phantom quality control. Three new tests were suggested to be made in the quality control of the Cone Beam: linearity, artifacts and alignment of the beam. (author)

  8. Quality control and radioprotection in dental cone beam computed tomography - case study

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Ligiane C.N.; Ferreira, Nadya M.P.D., E-mail: lnadya@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    The radiological protection in medical and odontologic radiology follows The Order (Portaria) 453/98 of the Ministry of Health, which presents the minimum set of tests for the constancy X-ray equipment. These tests follow the procedures set forth in the Resolution no. 64, the National Agency for Sanitary Vigilance. This work aims to show a study on dental cone beam computed tomography (CBCT), evaluating the physical parameters that influence the performance and image quality and presenting the appropriate tests to this new system. The authors analyzed the tests specific for computed tomography (CT) of the Resolution no. 64, feasibility assessment of them and if their interpretations are compatible with CBCT. Once determined if testing is feasible, compare with those presented in the manual provided by the equipment manufacturer. The CT scanner used was the Mini-Cat Tomography Scanner Xoran Technologies of KAVO. In the study it was verified that four tests could be reproduced in CBCT: noise, accuracy and uniformity in the number of CT of water and spatial resolution. Considering experimental data, the methodology and tolerance of manufacturer for the first two tests were more appropriate. For the uniformity test of the CT number, we recommend using the phantom quality control. Three new tests were suggested to be made in the quality control of the Cone Beam: linearity, artifacts and alignment of the beam. (author)

  9. Quality control beam of radiation through imaging system using a flat panel (ILD)

    International Nuclear Information System (INIS)

    Benitez Serrano, J. A.; Gomez Barrado, A.; Sanchez-Reyes, A.

    2013-01-01

    The daily quality checks of the accelerator include, among others, checks of the daily calibration, symmetry and uniformity of the radiation beam. Usually verification systems daily are used for this purpose, which employ arrays of detectors of solid-state or ionization chambers. This paper intends to carry out the control of quality through the irradiation of a number of fields in the portal imaging system and its subsequent analysis in software's own creation, as well as the comparison of results with the daily verification system. (Author)

  10. SU-C-201-07: Towards Clinical Cherenkov Emission Dosimetry: Stopping Power-To-Cherenkov Power Ratios and Beam Quality Specification of Clinical Electron Beams

    International Nuclear Information System (INIS)

    Zlateva, Y; Seuntjens, J; El Naqa, I

    2016-01-01

    Purpose: We propose a Cherenkov emission (CE)-based reference dosimetry method, which in contrast to ionization chamber-based dosimetry, employs spectrum-averaged electron restricted mass collision stopping power-to-Cherenkov power ratios (SCRs), and we examine Monte Carlo-calculated SCRs and beam quality specification of clinical electron beams. Methods: The EGSnrc user code SPRRZnrc was modified to compute SCRs instead of stopping-power ratios (single medium: water; cut-off: CE threshold (observing Spencer-Attix conditions); CE power: Frank-Tamm). SCRs are calculated with BEAMnrc for realistic electron beams with nominal energies of 6–22 MeV from three Varian accelerators (TrueBeam Clinac 21EX, Clinac 2100C/D) and for mono-energetic beams of energies equal to the mean electron energy at the water surface. Sources of deviation between clinical and mono-energetic SCRs are analyzed quantitatively. A universal fit for the beam-quality index R_5_0 in terms of the depth of 50% CE C_5_0 is carried out. Results: SCRs at reference depth are overestimated by mono-energetic values by up to 0.2% for a 6-MeV beam and underestimated by up to 2.3% for a 22-MeV beam. The variation is mainly due to the clinical beam spectrum and photon contamination. Beam angular spread has a small effect across all depths and energies. The influence of the electron spectrum becomes increasingly significant at large depths, while at shallow depths and high beam energies photon contamination is predominant (up to 2.0%). The universal data fit reveals a strong linear correlation between R_5_0 and C_5_0 (ρ > 0.99999). Conclusion: CE is inherent to radiotherapy beams and can be detected outside the beam with available optical technologies, which makes it an ideal candidate for out-of-beam high-resolution 3D dosimetry. Successful clinical implementation of CE dosimetry hinges on the development of robust protocols for converting measured CE to radiation dose. Our findings constitute a key step

  11. Impact of Spot Size and Beam-Shaping Devices on the Treatment Plan Quality for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Moteabbed, Maryam; Yock, Torunn I.; Depauw, Nicolas; Madden, Thomas M.; Kooy, Hanne M.; Paganetti, Harald

    2016-01-01

    Purpose: This study aimed to assess the clinical impact of spot size and the addition of apertures and range compensators on the treatment quality of pencil beam scanning (PBS) proton therapy and to define when PBS could improve on passive scattering proton therapy (PSPT). Methods and Materials: The patient cohort included 14 pediatric patients treated with PSPT. Six PBS plans were created and optimized for each patient using 3 spot sizes (∼12-, 5.4-, and 2.5-mm median sigma at isocenter for 90- to 230-MeV range) and adding apertures and compensators to plans with the 2 larger spots. Conformity and homogeneity indices, dose-volume histogram parameters, equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and integral dose were quantified and compared with the respective PSPT plans. Results: The results clearly indicated that PBS with the largest spots does not necessarily offer a dosimetric or clinical advantage over PSPT. With comparable target coverage, the mean dose (D_m_e_a_n) to healthy organs was on average 6.3% larger than PSPT when using this spot size. However, adding apertures to plans with large spots improved the treatment quality by decreasing the average D_m_e_a_n and EUD by up to 8.6% and 3.2% of the prescribed dose, respectively. Decreasing the spot size further improved all plans, lowering the average D_m_e_a_n and EUD by up to 11.6% and 10.9% compared with PSPT, respectively, and eliminated the need for beam-shaping devices. The NTCP decreased with spot size and addition of apertures, with maximum reduction of 5.4% relative to PSPT. Conclusions: The added benefit of using PBS strongly depends on the delivery configurations. Facilities limited to large spot sizes (>∼8 mm median sigma at isocenter) are recommended to use apertures to reduce treatment-related toxicities, at least for complex and/or small tumors.

  12. Factor selection for service quality evaluation: a hospital case study.

    Science.gov (United States)

    Ameryoun, Ahmad; Najafi, Seyedvahid; Nejati-Zarnaqi, Bayram; Khalilifar, Seyed Omid; Ajam, Mahdi; Ansarimoghadam, Ahmad

    2017-02-13

    Purpose The purpose of this paper is to develop a systematic approach to predict service quality dimension's influence on service quality using a novel analysis based on data envelopment and SERVQUAL. Design/methodology/approach To assess hospital service quality in Tehran, expectation and perception of those who received the services were evaluated using SERVQUAL. The hospital service quality dimensions were found by exploratory factor analysis (EFA). To compare customer expectation and perception, perceived service quality index (PSQI) was measured using a new method based on common weights. A novel sensitivity approach was used to test the service quality factor's impact on the PSQI. Findings A new service quality dimension named "trust in services" was found using EFA, which is not an original SERVQUAL factor. The approach was applied to assess the hospital's service quality. Since the PSQI value was 0.76 it showed that improvements are needed to meet customer expectations. The results showed the factor order that affect PSQI. "Trust in services" has the strongest influence on PSQI followed by "tangibles," "assurance," "empathy," and "responsiveness," respectively. Practical implications This work gives managers insight into service quality by following a systematic method; i.e., measuring perceived service quality from the customer viewpoint and service factors' impact on customer perception. Originality/value The procedure helps managers to select the required service quality dimensions which need improvement and predict their effects on customer perception.

  13. Factors Affecting Quality of Audit; Empirical Evidence from Iran ...

    African Journals Online (AJOL)

    This study examines factors affecting quality of audit using empirical evidence from Iran Quality of audit was seen as the degree to which an audit report is free from deficiencies and distortions which show up later on. The quality of an audit was measured in terms of an auditor's ability to report financial distortions willingly ...

  14. Factors Affecting Time, Cost and Quality Management in Building ...

    African Journals Online (AJOL)

    The study is an assessment of time, cost and quality management in the Nigerian construction industry, and it aims to explore time cost and quality management in the construction industry. The objective of the study is to identify factors affecting time; cost and quality management in building construction projects. This study ...

  15. Neoadjuvant hormonal therapy and external-beam radiotherapy versus external-beam irradiation alone for prostate cancer. A quality-of-life analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pinkawa, Michael; Piroth, Marc D.; Asadpour, Branka; Gagel, Bernd; Fischedick, Karin; Siluschek, Jaroslav; Kehl, Mareike; Krenkel, Barbara; Eble, Michael J. [RWTH Aachen (Germany). Dept. of Radiotherapy

    2009-02-15

    To evaluate the impact of neoadjuvant hormonal therapy (NHT) on quality of life after external-beam radiotherapy (EBRT) for prostate cancer. A group of 170 patients (85 with and 85 without NHT) has been surveyed prospectively before EBRT (70.2-72 Gy), at the last day of EBRT, a median time of 2 months and 15 months after EBRT using a validated questionnaire (Expanded Prostate Cancer Index Composite). Pairs with and without NHT (median treatment time of 3.5 months before EBRT) were matched according to the respective planning target volume and prostate volume. Before EBRT, significantly lower urinary function/bother, sexual function and hormonal function/bother scores were found for patients with NHT. More than 1 year after EBRT, only sexual function scores remained lower. In a multivariate analysis, NHT and adjuvant hormonal therapy (HT) versus NHT only (hazard ratio 14; 95% confidence interval 2.7-183; p = 0.02) and luteinizing hormone-releasing hormone (LHRH) agonists versus antiandrogens (hazard ratio 3.6; 95% confidence interval 1.1-12; p = 0.04) proved to be independent risk factors for long-term erectile dysfunction (no or very poor ability to have an erection). With the exception of sexual function (additional adjuvant HT and application of LHRH analog independently adverse), short-term NHT was not found to decrease quality of life after EBRT for prostate cancer. (orig.)

  16. Radiation quality factor of spherical antennas with material cores

    DEFF Research Database (Denmark)

    Hansen, Troels Vejle; Kim, Oleksiy S.; Breinbjerg, Olav

    2011-01-01

    This paper gives a description of the radiation quality factor and resonances of spherical antennas with material cores. Conditions for cavity and radiating resonances are given, and a theoretical description of the radiation quality factor, as well as simple expressions describing the relative...

  17. Quality- a Factor of Management in Road Transport of Goods

    Directory of Open Access Journals (Sweden)

    Livij Jakomin

    2012-10-01

    Full Text Available Providing services on a quality level is an important factorof management in the trade rivalry for the control over the market.The factors affecting quality comprise technical factors andoperational and organisational ones. The technical factors includethe choice, the due care and maintenance of the vehicle.The operational and organisational factors are the quality offer,performing the transport service, the response in case of action,and the information efficiency.The necessity to control the total quality management is theresponsibility of the management. All staff members must participatein the improvement of quality management in their particularworking environment. Improved quality managementprovides for a higher safety of business operation and jobs, resultingin enhanced social security, which is gaining importancein mutual relations.

  18. Modelling lateral beam quality variations in pencil kernel based photon dose calculations

    International Nuclear Information System (INIS)

    Nyholm, T; Olofsson, J; Ahnesjoe, A; Karlsson, M

    2006-01-01

    Standard treatment machines for external radiotherapy are designed to yield flat dose distributions at a representative treatment depth. The common method to reach this goal is to use a flattening filter to decrease the fluence in the centre of the beam. A side effect of this filtering is that the average energy of the beam is generally lower at a distance from the central axis, a phenomenon commonly referred to as off-axis softening. The off-axis softening results in a relative change in beam quality that is almost independent of machine brand and model. Central axis dose calculations using pencil beam kernels show no drastic loss in accuracy when the off-axis beam quality variations are neglected. However, for dose calculated at off-axis positions the effect should be considered, otherwise errors of several per cent can be introduced. This work proposes a method to explicitly include the effect of off-axis softening in pencil kernel based photon dose calculations for arbitrary positions in a radiation field. Variations of pencil kernel values are modelled through a generic relation between half value layer (HVL) thickness and off-axis position for standard treatment machines. The pencil kernel integration for dose calculation is performed through sampling of energy fluence and beam quality in sectors of concentric circles around the calculation point. The method is fully based on generic data and therefore does not require any specific measurements for characterization of the off-axis softening effect, provided that the machine performance is in agreement with the assumed HVL variations. The model is verified versus profile measurements at different depths and through a model self-consistency check, using the dose calculation model to estimate HVL values at off-axis positions. A comparison between calculated and measured profiles at different depths showed a maximum relative error of 4% without explicit modelling of off-axis softening. The maximum relative error

  19. Improving the beam quality of high-power laser diodes by introducing lateral periodicity into waveguides

    Science.gov (United States)

    Sobczak, Grzegorz; DÄ browska, ElŻbieta; Teodorczyk, Marian; Kalbarczyk, Joanna; MalÄ g, Andrzej

    2013-01-01

    Low quality of the optical beam emitted by high-power laser diodes is the main disadvantage of these devices. The two most important reasons are highly non-Gaussian beam profile with relatively wide divergence in the junction plane and the filamentation effect. Designing laser diode as an array of narrow, close to each other single-mode waveguides is one of the solutions to this problem. In such devices called phase locked arrays (PLA) there is no room for filaments formation. The consequence of optical coupling of many single-mode waveguides is the device emission in the form of few almost diffraction limited beams. Because of losses in regions between active stripes the PLA devices have, however, somewhat higher threshold current and lower slope efficiencies compared to wide-stripe devices of similar geometry. In this work the concept of the high-power laser diode resonator consisted of joined PLA and wide stripe segments is proposed. Resulting changes of electro-optical characteristics of PLA are discussed. The devices are based on the asymmetric heterostructure designed for improvement of the catastrophic optical damage threshold as well as thermal and electrical resistances. Due to reduced distance from the active layer to surface in this heterostructure, better stability of current (and gain) distribution with changing drive level is expected. This could lead to better stability of optical field distribution and supermodes control. The beam divergence reduction in the direction perpendicular of the junction plane has been also achieved.

  20. Factors Determining e-Learning Service Quality

    Science.gov (United States)

    Uppal, Muhammad Amaad; Ali, Samnan; Gulliver, Stephen R.

    2018-01-01

    e-Learning courses are fast becoming common-place, yet the success of these online courses varies considerably. Since limited research addresses the issue of e-learning quality (ELQ) of service in higher education environments, there is an increasing need to effectively assess ELQ. In this paper, we argue that to obtain a satisfactory e-learning…

  1. High-quality electron beam generation in a proton-driven hollow plasma wakefield accelerator

    Science.gov (United States)

    Li, Y.; Xia, G.; Lotov, K. V.; Sosedkin, A. P.; Hanahoe, K.; Mete-Apsimon, O.

    2017-10-01

    Simulations of proton-driven plasma wakefield accelerators have demonstrated substantially higher accelerating gradients compared to conventional accelerators and the viability of accelerating electrons to the energy frontier in a single plasma stage. However, due to the strong intrinsic transverse fields varying both radially and in time, the witness beam quality is still far from suitable for practical application in future colliders. Here we demonstrate the efficient acceleration of electrons in proton-driven wakefields in a hollow plasma channel. In this regime, the witness bunch is positioned in the region with a strong accelerating field, free from plasma electrons and ions. We show that the electron beam carrying the charge of about 10% of 1 TeV proton driver charge can be accelerated to 0.6 TeV with a preserved normalized emittance in a single channel of 700 m. This high-quality and high-charge beam may pave the way for the development of future plasma-based energy frontier colliders.

  2. Factors Associated with Sleep Quality in Maxillectomy Patients.

    Science.gov (United States)

    Li, Na; Otomaru, Takafumi; Said, Mohamed Moustafa; Kanazaki, Ayako; Yeerken, Yesiboli; Taniguchi, Hisashi

    To investigate factors affecting sleep quality in maxillectomy patients after prosthetic rehabilitation and to determine the association between defect status and sleep quality. A total of 57 patients participated in this study. Sleep quality, general health, and oral health-related quality of life (OHRQoL) were evaluated. Of the total sample, 89% had poor sleep quality. Early morning awakening and daytime sleepiness were the most common complaints. Defect status and the extent of neck dissection could affect sleep quality in these patients. Improvement of OHRQoL in patients with dentomaxillary prostheses may help improve sleep.

  3. THE FACTORS FORMING QUALITY OF GRANULATED SUGAR

    Directory of Open Access Journals (Sweden)

    N. G. Kulneva

    2015-01-01

    Full Text Available Sugar, with good taste and high caloric, is one of the most popular human food. Consumers sugar must be sure that the sugar under normal conditions of use is of high quality and is not harmful to the health of the product. One reason for the decline in the quality of sugar is bacterial contamination. This is because the sugar industry products are good targets for the development of different groups of microorganisms, e.g., Bacillus subtilis, Clostridium perfringes, Leuconostoc dextranicum, Torula alba, Pseudomonas fluorescens, Sarcina lutea and others. These organisms are affected with beets, and then with sugar beet chips and diffusion juice fall into the processing line of sugar production. Their number in the diffusion juice varies and depends on many facto rs such as the quality of raw materials, the quality of cleaning beet root colonization of transporter-washing and the supply of water to the diffusion process, the temperature of the diffusion and others. In the diffusion unit has the most favorable conditions for the development of micro-organisms. Some of them, especially resistant bacteria and thermophilic bacteria or their spores, forming a capsule which protects against external influences occur in the final product sugar. When injected into the fresh crop of product (juice, syrup, they begin to multiply rapidly, causing difficulties in the process. The higher seeding beet microorganisms, the more they decompose and emit sucrose metabolism byproducts. To reduce the negative impact of microbiological and reduce losses from decomposition of sucrose conducted research on the possibility of using chlorine-containing substances in the sugar industry. It was established experimentally that the investigated chlorinated drug has bacteriostatic action and can be recommended for use in sugar beet production.

  4. Comparison of surface roughness quality created by abrasive water jet and CO2 laser beam cutting

    Czech Academy of Sciences Publication Activity Database

    Zeleňák, M.; Valíček, Jan; Klich, Jiří; Židková, P.

    2012-01-01

    Roč. 19, č. 3 (2012), s. 481-485 ISSN 1330-3651 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : abrasive waterjet cut ting * CO2 laser beam cut ting * optical profilometry * titanium sample Subject RIV: JQ - Machines ; Tools Impact factor: 0.601, year: 2012 http://hrcak.srce.hr/index.php?show=clanak&id_clanak_jezik=129054

  5. Determination of neutron beam quality and evaluation of image quality (neutron radiography technique)

    International Nuclear Information System (INIS)

    Wan Muhammad Saridan Wan Hassan; Manan Munhamad Jaib; Ng Sook Kien; Lai Zhong Yuan; Azali Muhammad; Abd Aziz Mohamed; Mohd Rawi Abdullah

    2005-01-01

    The following topics were presented: beam purity Indicator (BPI) and sensitivity indicator (SI) test objects (ASTM E545-91); No Numbra (NU) test object (ASTM E803-91); MTF and Noise; parameters used in calculation; results of the experiments; summary of analysis. The resulting data consisted exposure contributors and sensitivity levels for films that were radiographed along with 0.25 and 0.5 mm Gd converters; visibility of holes and gaps on the image of the sensitivity indicator using both 0.25 and 0.5 mm Gd converters; qualitative data obtained from observation of the blurring effect on the lower boron nitride disc for both 0.25 and 0.5 mm Gd converters

  6. Impact of large x-ray beam collimation on image quality

    Science.gov (United States)

    Racine, Damien; Ba, Alexandre; Ott, Julien G.; Bochud, François O.; Verdun, Francis R.

    2016-03-01

    Large X-ray beam collimation in computed tomography (CT) opens the way to new image acquisition techniques and improves patient management for several clinical indications. The systems that offer large X-ray beam collimation enable, in particular, a whole region of interest to be investigated with an excellent temporal resolution. However, one of the potential drawbacks of this option might be a noticeable difference in image quality along the z-axis when compared with the standard helical acquisition mode using more restricted X-ray beam collimations. The aim of this project is to investigate the impact of the use of large X-ray beam collimation and new iterative reconstruction on noise properties, spatial resolution and low contrast detectability (LCD). An anthropomorphic phantom and a custom made phantom were scanned on a GE Revolution CT. The images were reconstructed respectively with ASIR-V at 0% and 50%. Noise power spectra, to evaluate the noise properties, and Target Transfer Functions, to evaluate the spatial resolution, were computed. Then, a Channelized Hotelling Observer with Gabor and Dense Difference of Gaussian channels was used to evaluate the LCD using the Percentage correct as a figure of merit. Noticeable differences of 3D noise power spectra and MTF have been recorded; however no significant difference appeared when dealing with the LCD criteria. As expected the use of iterative reconstruction, for a given CTDIvol level, allowed a significant gain in LCD in comparison to ASIR-V 0%. In addition, the outcomes of the NPS and TTF metrics led to results that would contradict the outcomes of CHO model observers if used for a NPWE model observer (Non- Prewhitening With Eye filter). The unit investigated provides major advantages for cardiac diagnosis without impairing the image quality level of standard chest or abdominal acquisitions.

  7. Evaluation of Skin Dose and Image Quality on Cone Beam Computed Tomography

    International Nuclear Information System (INIS)

    Ahn, Jong Ho; Hong, Chae Seon; Kim, Jin Man; Jang, Jun Young

    2008-01-01

    Cone-beam CT using linear accelerator attached to on-board imager is a image guided therapy equipment. Because it is to check the patient's set-up error, correction, organ and target movement. But imaging dose should be cause of the secondary cancer when taking a image. The aim of this study is investigation of appropriate cone beam CT scan mode to compare and estimate the image quality and skin dose. Measurement by Thermoluminescence dosimeter (TLD-100, Harshaw) with using the Rando phantom are placed on each eight sites in separately H and N, thoracic, abdominal section. each 4 methods of scan modes of are measured the for skin dose in three time. Subsequently, obtained average value. Following image quality QA protocol of equipment manufacturers using the catphan 504 phantom, image quality of each scan mode is compared and analyzed. The results of the measured skin dose are described in here. The skin dose of Head and Neck are measured mode A: 8.96 cGy, mode B: 4.59 cGy, mode C: 3.46 cGy mode D: 1.76 cGy and thoracic mode A: 9.42 cGy, mode B: 4.58 cGy, mode C: 3.65 cGy, mode D: 1.85 cGy, and abdominal mode A: 9.97 cGy, mode B: 5.12 cGy, mode C: 4.03 cGy, mode D: 2.21 cGy. Approximately, dose of mode B are reduced 50%, mode C are reduced 60%, mode D are reduced 80% a point of reference dose of mode A. the results of analyzed HU reproducibility, low contrast resolution, spatial resolution (high contrast resolution), HU uniformity in evaluation item of image quality are within the tolerance value by recommended equipment manufacturer in all scan mode. Maintaining the image quality as well as reducing the image dose are very important in cone beam CT. In the result of this study, we are considered when to take mode A when interested in soft tissue. And we are considered to take mode D when interested in bone scan and we are considered to take mode B, C when standard scan. Increasing secondary cancer risk due to cone beam CT scan should be reduced by low m

  8. Optimization of the pion beam for the HADES detector and determination of the η form factor in proton-proton reactions at 2.2 GeV

    International Nuclear Information System (INIS)

    Spruck, Bjoern

    2008-01-01

    This thesis contains two tasks. The first part focuses on the development and optimization of the pion beam facility for the HADES experiment. The second part describes the measurement of the electromagnetic transition form factor of the η meson in proton-proton reactions. To investigate pion-nucleon reaction, a secondary pion beam is required. The pions are produced by a heavy ion beam impinging on a beryllium target. In order to determine the profile of the beam focus, two scintillating fiber detectors have been built as part of this thesis and are read out with recently developed electronics. The measured size of the beam focus appeared to be not acceptable, which can be attributed to the achromatic magnetic focusing in the beam line. Simulations have shown, that an additional quadrupole magnet directly in front of HADES would solve this problem and improve the beam quality. A test experiment including this new quadrupole has been performed and the analysis is still in progress. Preliminary results show a significant reduction of the momentum dependency of the focus. The size of the actual beam spot has been deduced to 14 mm by using an indirect tracking approach. For deducing the electromagnetic structure of hadrons, a first step has been done by analyzing the η Dalitz decay in p+p reactions at 2.2 GeV kinetic energy to determine the electromagnetic transition form factor of the η meson. A fit to the data leads to a form factor slope of b=2.2 -1.4 +1.2 GeV -2 . This corresponds to a pole mass of λ=680 -130 +460 MeV/c 2 . It has been shown, that a semi-exclusive analysis of the η Dalitz decay within the event hypothesis framework including a kinematical fit is feasible. (orig.)

  9. Soft X-ray generation via inverse compton scattering between high quality electron beam and high power laser

    International Nuclear Information System (INIS)

    Masakazu Washio; Kazuyuki Sakaue; Yoshimasa Hama; Yoshio Kamiya; Tomoko Gowa; Akihiko Masuda; Aki Murata; Ryo Moriyama; Shigeru Kashiwagi; Junji Urakawa

    2007-01-01

    High quality beam generation project based on High-Tech Research Center Project, which has been approved by Ministry of Education, Culture, Sports, Science and Technology in 1999, has been conducted by advance research institute for science and engineering, Waseda University. In the project, laser photo-cathode RF-gun has been selected for the high quality electron beam source. RF cavities with low dark current, which were made by diamond turning technique, have been successfully manufactured. The low emittance electron beam was realized by choosing the modified laser injection technique. The obtained normalized emmitance was about 3 m.mrad at 100 pC of electron charge. The soft x-ray beam generation with the energy of 370 eV, which is in the energy region of so-called water window, by inverse Compton scattering has been performed by the collision between IR laser and the low emmitance electron beams. (Author)

  10. Dosimetry quality audit of high energy photon beams in greek radiotherapy centers

    International Nuclear Information System (INIS)

    Hourdakis, Constantine J.; Boziari, A.

    2008-01-01

    Background and purpose: Dosimetry quality audits and intercomparisons in radiotherapy centers is a useful tool in order to enhance the confidence for an accurate therapy and to explore and dissolve discrepancies in dose delivery. This is the first national comprehensive study that has been carried out in Greece. During 2002 - 2006 the Greek Atomic Energy Commission performed a dosimetry quality audit of high energy external photon beams in all (23) Greek radiotherapy centers, where 31 linacs and 13 Co-60 teletherapy units were assessed in terms of their mechanical performance characteristics and relative and absolute dosimetry. Materials and Methods: The quality audit in dosimetry of external photon beams took place by means of on-site visits, where certain parameters of the photon beams were measured, calculated and assessed according to a specific protocol and the IAEA TRS 398 dosimetry code of practice. In each radiotherapy unit (Linac or Co-60), certain functional parameters were measured and the results were compared to tolerance values and limits. Doses in water under reference and non reference conditions were measured and compared to the stated values. Also, the treatment planning systems (TPS) were evaluated with respect to irradiation time calculations. Results: The results of the mechanical tests, dosimetry measurements and TPS evaluation have been presented in this work and discussed in detail. This study showed that Co-60 units had worse performance mechanical characteristics than linacs. 28% of all irradiation units (23% of linacs and 42% of Co-60 units) exceeded the acceptance limit at least in one mechanical parameter. Dosimetry accuracy was much worse in Co60 units than in linacs. 61% of the Co60 units exhibited deviations outside ±3% and 31% outside ±5%. The relevant percentages for the linacs were 24% and 7% respectively. The results were grouped for each hospital and the sources of errors (functional and human) have been investigated and

  11. Dosimetry quality audit of high energy photon beams in greek radiotherapy centers.

    Science.gov (United States)

    Hourdakis, Constantine J; Boziari, A

    2008-04-01

    Dosimetry quality audits and intercomparisons in radiotherapy centers is a useful tool in order to enhance the confidence for an accurate therapy and to explore and dissolve discrepancies in dose delivery. This is the first national comprehensive study that has been carried out in Greece. During 2002--2006 the Greek Atomic Energy Commission performed a dosimetry quality audit of high energy external photon beams in all (23) Greek radiotherapy centers, where 31 linacs and 13 Co-60 teletherapy units were assessed in terms of their mechanical performance characteristics and relative and absolute dosimetry. The quality audit in dosimetry of external photon beams took place by means of on-site visits, where certain parameters of the photon beams were measured, calculated and assessed according to a specific protocol and the IAEA TRS 398 dosimetry code of practice. In each radiotherapy unit (Linac or Co-60), certain functional parameters were measured and the results were compared to tolerance values and limits. Doses in water under reference and non reference conditions were measured and compared to the stated values. Also, the treatment planning systems (TPS) were evaluated with respect to irradiation time calculations. The results of the mechanical tests, dosimetry measurements and TPS evaluation have been presented in this work and discussed in detail. This study showed that Co-60 units had worse performance mechanical characteristics than linacs. 28% of all irradiation units (23% of linacs and 42% of Co-60 units) exceeded the acceptance limit at least in one mechanical parameter. Dosimetry accuracy was much worse in Co60 units than in linacs. 61% of the Co60 units exhibited deviations outside +/-3% and 31% outside +/-5%. The relevant percentages for the linacs were 24% and 7% respectively. The results were grouped for each hospital and the sources of errors (functional and human) have been investigated and discussed in details. This quality audit proved to be a

  12. Study on the output factors of asymmetrical rectangular electron beam field

    International Nuclear Information System (INIS)

    Chen Yinghai; Yang Yueqin; Ma Yuhong; Zheng Jin; Zou Lijuan

    2009-01-01

    Objective: To evaluate the variant regularity of the output factors of asymmetrical rectangular electron beam field. Methods: The output factors of three special fields with different applicators and energies were measured by ionization chamber method at different off-axis distances. Then deviations of the output factors between asymmetrical and symmetric rectangular fields were calculated. Results: The changes of output factor with different off-axis distances in asymmetrical rectangular fields were basically consistent with those in standard square fields with the same applicator. It revealed that the output factor of asymmetrical rectangular field was related with the off-axis ratio of standard square field. Applicator and field size did not show obvious influence on the output factor. Conclusions: The output factor changes of asymmetrical rectangular field are mainly correlated with the off-axis ratio of standard square field. The correction of the output factor is determined by the off-axis ratio changes in standard square field. (authors)

  13. LHCB: A LHCb-VELO module as beam quality monitor for proton therapy beam at the Clatterbridge Centre for Oncology

    CERN Multimedia

    Casse, G; Patel, G D; Smith, N A; Kacperek, A; Marsland, B

    2010-01-01

    The progress in detector technology, driven by the needs of particle tracking and vertexing in the present LHC and its upgrade (sLHC), has led to the design of silicon sensors with low mass, high granularity, high speed and unprecedented radiation hardness. The sensors designed for such a harsh environment can be profitably used for instrumenting the control systems of therapeutic hadron beams. The high granularity and readout clock speed are well suited for monitoring continuous beam currents. The low mass allows reduced interference with the beam whilst monitoring its profile with high precision. The high resolution and sensitivity to minimum ionising particles allows monitoring of the beam spot position by measurement of the halo in real time, without any interference with the beam spot used in therapy.

  14. An analysis of main factors in electron beam flue gas purification

    International Nuclear Information System (INIS)

    Zhang Ming; Xu Guang

    2003-01-01

    Electron beam flue gas purification method is developing very quickly in recent years. Based on the experiment setting for electron beam flue gas purification in Institute of Nuclear Energy and Technology, Tsinghua University, how the technique factors affect the ratio of desulphurization and denitrogenation are described. Radiation dose (D), temperature (T), humidity (H), pour ammonia quantity (α) and initial concentration of SO 2 (C SO 2 ) and NO x (C NO x ) are main factors influencing flue gas purification. Using the methods of correlation analysis and regression analysis, the primary effect factors are found out and the regression equations are set to optimize the system process, predigest the system structure and to forecast the experimental results. (authors)

  15. An automated procedure for the quality assurance of electron beam output and energy

    International Nuclear Information System (INIS)

    Woo, M.K.; Videla, N.G.

    2004-01-01

    In this article, we report on the development of a simple and accurate method for quality assurance of electron beam output and energy. Aluminum disks of thicknesses d max or d 50 of the particular electron energy are positioned sequentially over a parallel-plate ion chamber and the ratio of the two signals is compared to the standard. The positioning of the aluminum disks is carried out remotely and automatically to eliminate the necessity of multiple setups. One method utilizes the remote control feature of the treatment couch and another employs a motor-driven carousel. The superior sensitivity over a commercially available energy monitor is illustrated

  16. Method of controlling coherent synchroton radiation-driven degradation of beam quality during bunch length compression

    Science.gov (United States)

    Douglas, David R [Newport News, VA; Tennant, Christopher D [Williamsburg, VA

    2012-07-10

    A method of avoiding CSR induced beam quality defects in free electron laser operation by a) controlling the rate of compression and b) using a novel means of integrating the compression with the remainder of the transport system: both are accomplished by means of dispersion modulation. A large dispersion is created in the penultimate dipole magnet of the compression region leading to rapid compression; this large dispersion is demagnified and dispersion suppression performed in a final small dipole. As a result, the bunch is short for only a small angular extent of the transport, and the resulting CSR excitation is small.

  17. A service for monitoring the quality of intraoperative cone beam CT images

    Directory of Open Access Journals (Sweden)

    Heckel Frank

    2016-09-01

    Full Text Available In recent years, operating rooms (ORs have transformed into integrated operating rooms, where devices are able to communicate, exchange data, or even steer and control each other. However, image data processing is commonly done by dedicated workstations for specific clinical use-cases. In this paper, we propose a concept for a dynamic service component for image data processing on the example of automatic image quality assessment (AQUA of intraoperative cone beam computed tomography (CBCT images. The service is build using the Open Surgical Communication Protocol (OSCP and the standard for Digital Imaging and Communications in Medicine (DICOM. We have validated the proposed concept in an integrated demonstrator OR.

  18. Evaluation of diet quality of the elderly and associated factors.

    Science.gov (United States)

    Pinto de Souza Fernandes, Dalila; Duarte, Maria Sônia Lopes; Pessoa, Milene Cristine; Franceschini, Sylvia do Carmo Castro; Ribeiro, Andréia Queiroz

    2017-09-01

    Observational studies suggest healthy dietary patterns are associated with risk reduction and better control of various chronic diseases. However, few Brazilian studies have focused on evaluating the quality of the elderly diet and its relationship with diseases. This study aimed to estimate the association between diet quality and socioeconomic factors, health and nutrition of the elderly. This is a cross-sectional population-based study whose target population were non-institutionalized elderly residents in the city of Viçosa, Brazil. Anthropometric, socioeconomic, health conditions, lifestyle and food consumption variables were obtained from a semi-structured questionnaire. The quality of the diet was assessed by the revised Healthy Eating Index classified into tertiles, considering the first tertile as "Poor diet quality," the second as 'Intermediate diet quality' and the third as "Better diet quality." To identify factors independently associated with diet quality model, the works used multinomial logistic regression. In the results of the multivariate analysis, the factors independently associated with "better diet quality" included female gender, higher education, history of one to five medical visits in the past year, history of diabetes mellitus, dyslipidemia and the use of polypharmacy. Our results show that most seniors need to improve the quality of their diet and those of male gender with no or little education, and those who do not seek medical services constitute the group that needs attention concerning the measures to improve the quality of their diet. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Improvement in beam quality of the JAEA AVF cyclotron for focusing heavy-ion beams with energies of hundreds of MeV

    International Nuclear Information System (INIS)

    Kurashima, Satoshi; Miyawaki, Nobumasa; Okumura, Susumu; Oikawa, Masakazu; Yoshida, Ken-ichi; Kamiya, Tomihiro; Fukuda, Mitsuhiro; Satoh, Takahiro; Nara, Takayuki; Agematsu, Takashi; Ishibori, Ikuo; Yokota, Watalu; Nakamura, Yoshiteru

    2007-01-01

    In order to achieve a heavy-ion microbeam with an energy of hundreds of MeV applied to the research fields of biotechnology and materials science, the JAEA AVF cyclotron (K = 110) has been upgraded to provide a high quality beam with a smaller energy spread and a higher current stability. A flat-top (FT) acceleration system of the cyclotron, designed to produce ion beams with an energy spread of ΔE/E ≤ 0.02%, has been developed to reduce chromatic aberrations in the lenses of the focusing microbeam system. The FT acceleration system provides uniform energy gain of the beam by superimposing a fifth-harmonic voltage on the fundamental one. In addition, stabilization of the acceleration rf voltage and the phase were achieved to accelerate the high quality beam and to provide it stably to the microbeam system connected to a cyclotron beam line. In the latest experiment, we have succeeded to accelerate 260 MeV 20 Ne 7+ with an energy spread of 0.05% in FWHM using the FT acceleration system

  20. Investigation of cone-beam CT image quality trade-off for image-guided radiation therapy

    Science.gov (United States)

    Bian, Junguo; Sharp, Gregory C.; Park, Yang-Kyun; Ouyang, Jinsong; Bortfeld, Thomas; El Fakhri, Georges

    2016-05-01

    It is well-known that projections acquired over an angular range slightly over 180° (so-called short scan) are sufficient for fan-beam reconstruction. However, due to practical imaging conditions (projection data and reconstruction image discretization, physical factors, and data noise), the short-scan reconstructions may have different appearances and properties from the full-scan (scans over 360°) reconstructions. Nevertheless, short-scan configurations have been used in applications such as cone-beam CT (CBCT) for head-neck-cancer image-guided radiation therapy (IGRT) that only requires a small field of view due to the potential reduced imaging time and dose. In this work, we studied the image quality trade-off for full, short, and full/short scan configurations with both conventional filtered-backprojection (FBP) reconstruction and iterative reconstruction algorithms based on total-variation (TV) minimization for head-neck-cancer IGRT. Anthropomorphic and Catphan phantoms were scanned at different exposure levels with a clinical scanner used in IGRT. Both visualization- and numerical-metric-based evaluation studies were performed. The results indicate that the optimal exposure level and number of views are in the middle range for both FBP and TV-based iterative algorithms and the optimization is object-dependent and task-dependent. The optimal view numbers decrease with the total exposure levels for both FBP and TV-based algorithms. The results also indicate there are slight differences between FBP and TV-based iterative algorithms for the image quality trade-off: FBP seems to be more in favor of larger number of views while the TV-based algorithm is more robust to different data conditions (number of views and exposure levels) than the FBP algorithm. The studies can provide a general guideline for image-quality optimization for CBCT used in IGRT and other applications.

  1. High quality electron beams from a plasma channel guided laser wakefield accelerator

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, Cs.; Tilborg, J. van; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2004-01-01

    Laser driven accelerators, in which particles are accelerated by the electric field of a plasma wave driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV/m. These fields are thousands of times those achievable in conventional radiofrequency (RF) accelerators, spurring interest in laser accelerators as compact next generation sources of energetic electrons and radiation. To date however, acceleration distances have been severely limited by lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low energy beams with 100% electron energy spread, limiting applications. Here we demonstrate that a relativistically intense laser can be guided by a preformed plasma density channel and that the longer propagation distance can result in electron beams of percent energy spread with low emittance and increased energy, containing >10 9 electrons above 80 MeV. The preformed plasma channel technique forms the basis of a new class of accelerators, combining beam quality comparable to RF accelerators with the high gradients of laser accelerators to produce compact tunable high brightness electron and radiation sources

  2. Effects of data sampling rate on image quality in fan-beam-CT system

    International Nuclear Information System (INIS)

    Iwata, Akira; Yamagishi, Nobutoshi; Suzumura, Nobuo; Horiba, Isao.

    1984-01-01

    Investigation was made into the relationship between spatial resolution or artifacts and data sampling rate in order to pursue the causes of the degradation of CT image quality by computer simulation. First the generation of projection data and reconstruction calculating process are described, and then the results are shown about the relation between angular sampling interval and spatical resolution or artifacts, and about the relation between projection data sampling interval and spatial resolution or artifacts. It was clarified that the formulation of the relationship between spatial resolution and data sampling rate performed so far for parallel X-ray beam was able to be applied to fan beam. As a conclusion, when other reconstruction parameters are the same in fan beam CT systems, spatial resolution can be determined by projection data sampling rate rather than angular sampling rate. The mechanism of artifact generation due to the insufficient number of angular samples was made clear. It was also made clear that there was a definite relationship among measuring region, angular sampling rate and projection data sampling rate, and the amount of artifacts depending upon projection data sampling rate was proportional to the amount of spatial frequency components (Aliasing components) of a test object above the Nyquist frequency of projection data. (Wakatsuki, Y.)

  3. Training, Quality Assurance Factors, and Tools Investigation: a Work Report and Suggestions on Software Quality Assurance

    Science.gov (United States)

    Lee, Pen-Nan

    1991-01-01

    Previously, several research tasks have been conducted, some observations were obtained, and several possible suggestions have been contemplated involving software quality assurance engineering at NASA Johnson. These research tasks are briefly described. Also, a brief discussion is given on the role of software quality assurance in software engineering along with some observations and suggestions. A brief discussion on a training program for software quality assurance engineers is provided. A list of assurance factors as well as quality factors are also included. Finally, a process model which can be used for searching and collecting software quality assurance tools is presented.

  4. Dietary quality, lifestile factors and healthy ageing in Europe

    NARCIS (Netherlands)

    Haveman-Nies, A.

    2001-01-01

    Keywords: dietary quality, dietary patterns, lifestyle factors, smoking, physical activity, elderly, mortality, Mediterranean Diet Score, Healthy Diet Indicator, healthy ageing, self-rated health, functional status


    The contribution

  5. Normal modes and quality factors of spherical dielectric resonators: I ...

    Indian Academy of Sciences (India)

    Eigenmodes; spherical resonators; spherical dielectric resonators; quality factors. PACS No. 42.50. .... Alternatively, introducing the angular momentum operator L defined as, L = (1/j)( r × ∇) ...... referee of the article for some helpful comments.

  6. Molecular Beam Epitaxy Growth of High Crystalline Quality LiNbO3

    Science.gov (United States)

    Tellekamp, M. Brooks; Shank, Joshua C.; Goorsky, Mark S.; Doolittle, W. Alan

    2016-12-01

    Lithium niobate is a multi-functional material with wide reaching applications in acoustics, optics, and electronics. Commercial applications for lithium niobate require high crystalline quality currently limited to bulk and ion sliced material. Thin film lithium niobate is an attractive option for a variety of integrated devices, but the research effort has been stagnant due to poor material quality. Both lattice matched and mismatched lithium niobate are grown by molecular beam epitaxy and studied to understand the role of substrate and temperature on nucleation conditions and material quality. Growth on sapphire produces partially coalesced columnar grains with atomically flat plateaus and no twin planes. A symmetric rocking curve shows a narrow linewidth with a full width at half-maximum (FWHM) of 8.6 arcsec (0.0024°), which is comparable to the 5.8 arcsec rocking curve FWHM of the substrate, while the film asymmetric rocking curve is 510 arcsec FWHM. These values indicate that the individual grains are relatively free of long-range disorder detectable by x-ray diffraction with minimal measurable tilt and twist and represents the highest structural quality epitaxial material grown on lattice mismatched sapphire without twin planes. Lithium niobate is also grown on lithium tantalate producing high quality coalesced material without twin planes and with a symmetric rocking curve of 193 arcsec, which is nearly equal to the substrate rocking curve of 194 arcsec. The surface morphology of lithium niobate on lithium tantalate is shown to be atomically flat by atomic force microscopy.

  7. External beam irradiation for choroid metastases: identification of factors predisposing to long-term sequelae

    International Nuclear Information System (INIS)

    Rudoler, Shari B.; Corn, Benjamin W.; Shields, Carol L.; De Potter, Patrick; Hyslop, Terry; Shields, Jerry A.; Curran, Walter J.

    1997-01-01

    Purpose: To improve overall quality of life, palliative treatments should attempt to minimize associated complications while effectively controlling specific symptoms. We reviewed our experience treating posterior uveal metastases with external beam radiotherapy (EBRT) to determine the complication rate and to identify the relationship between patient, tumor, or treatment-related factors and the development of ocular complications. Methods and Materials: 483 consecutive patients (pts) (578 eyes) were diagnosed with intraocular metastatic disease from solid tumors between 1972-1995. Of these, 233 eyes (188 pts) had lesions of the posterior uveal tract and received EBRT. Median follow-up time was 5.8 months (range: 0.7-170.0 months). Follow-up information regarding the development of complications was documented for 230 eyes. Complete EBRT details were available for 189 eyes. Seventy-two percent of the patients received 30.0-40.0 Gy in 2.0-3.0 Gy fractions. Biologically effective dose (BED) was calculated to allow meaningful comparisons between various fractionation regimens and total doses. Concurrent chemotherapy and/or hormonal therapy was used for 101 eyes (44%). Results: Median BED was 61 Gy 3 (range, 6.7-105 Gy 3 ), and 80% of treated eyes received BED 50-70 Gy 3 . EBRT energies included photons (70%), 60 Co (19%), electrons (6%), mixed energies (3%), and orthovoltage (2%). Lens-sparing techniques were used in 136 eyes (71%). At last follow-up 28 eyes (12%) developed one or more significant complications, including cataracts (16 eyes), radiation retinopathy (6 eyes), optic neuropathy (5 eyes), exposure keratopathy (5 eyes), and neovascularization of the iris (4 eyes). Two eyes developed narrow-angle glaucoma, and one of these required enucleation. On univariate analysis, Caucasian race (vs. Black/Hispanic, p = 0.03), increased intraocular pressure at diagnosis (>21 mmHg, p = 0.02), and diagnosis by biopsy (vs. no biopsy, p = 0.03) predisposed toward the

  8. A criterion-based audit of the technical quality of external beam radiotherapy for prostate cancer

    International Nuclear Information System (INIS)

    Brundage, Michael; Danielson, Brita; Pearcey, Robert; Bass, Brenda; Pickles, Tom; Bahary, Jean-Paul; Peng, Yingwei; Wallace, David; Mackillop, William

    2013-01-01

    Purpose: To evaluate the technical quality of external beam radiotherapy for prostate cancer in Canada. Methods: This was a multi-institution, retrospective study of a random sample of patients undergoing radiotherapy (RT) for prostate cancer in Canada. Patterns of care were determined by abstracting details of the patients’ management from original records. The quality of patient’s technical care was measured against a previously published, comprehensive suite of quality indicators. Results: 32 of the 37 RT centres participated. The total study population of 810 patients included 25% low-risk, 44% intermediate-risk, and 28% high-risk cases. 649 received external beam RT (EBRT) only, for whom compliance with 12 indicators of the quality of pre-treatment assessment ranged from 56% (sexual function documented) to 96% (staging bone scan obtained in high-risk patients). Compliance with treatment-related indicators ranged from 78% (dose to prostate ⩾74 Gy in intermediate risk patients not receiving hormone therapy) to 100% (3DCRT or IMRT plan). Compliance varied among centres; no centre demonstrated 100% compliance on all indicators and every centre was 100% compliant on at least some indicators. The number of assessment-related indicators (n = 13) with which a given centre was 100% compliant ranged from 4 to 11 (median 7) and the number of the treatment-specific indicators (n = 8) with which a given centre was 100% compliant ranged from 6 to 8 (median 8). ADT therapy was utilised in most high-risk cases (191, 92.3%). Conclusions: While patterns of prostate cancer care in Canada vary somewhat, compliance on the majority of quality indicators is very high. However, all centres showed room for improvement on several indicators and few individual patients received care that met target benchmarks on all quality measures. This variation is particularly important for indicators such as delivered dose where impact on disease outcome is known to exist, and suggests that

  9. High quality atomically thin PtSe2 films grown by molecular beam epitaxy

    Science.gov (United States)

    Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

    2017-12-01

    Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

  10. Factors impacting on the microbiological quality and safety of ...

    African Journals Online (AJOL)

    Problems with the safety and shelf life of export hake have been raised by the Namibian fishing industry. This prompted an investigation into the factors that may have an impact on the microbiological quality and safety of processed hake. Samples were collected along the processing line; the general microbiological quality ...

  11. Quality control of a kV cone beam computed tomography imaging system

    International Nuclear Information System (INIS)

    Marguet, M.; Bodez, V.

    2009-01-01

    Purpose: This work presents the introduction of a quality assurance program for the On-Board Imager (O.B.I., Varian) kV cone beam computed tomography (kV C.B.C.T.) system, together with the results of 1 year monthly testing. Materials and methods: Firstly the geometric precision and stability of the equipment and of the associated software were evaluated using the Marker phantom. The coincidence of the accelerator isocenter and the imager isocenter was verified as well as the accuracy of the registration of kV cone beam computed tomography (kV C.B.C.T.) with reference CT images. Then, the kV C.B.C.T. image quality was evaluated using the Catphan 504 phantom and ArtiScan software (Aquilab) for both full-fan (F.F.) and half-fan (H.F.) imaging modes. Results: The kV C.B.C.T. isocenter and image registration with correction of the table position were found to be within a tolerance of 2.0 mm. Concerning the kV C.B.C.T. image quality, image noise and uniformity, the Hounsfield units (HU) stability and linearity, geometric distortion and high contrast resolution were all found to be within the manufacturer's recommendations for both F.F. and H.F. modes. However, the low contrast resolution for the HF mode did not meet the manufacturer's specifications. Conclusion: The quality assurance tests introduced have defined the initial system characteristics and their evolution during a period of 1 year, demonstrating the stability of the O.B.I.. (authors)

  12. Quality control of JEOL JBX-9500FSZ e-beam lithography system in a multi-user laboratory

    DEFF Research Database (Denmark)

    Greibe, Tine; Anhøj, Thomas Aarøe; Johansen, Leif

    2016-01-01

    designed quality control procedure characterized using a scanning electron microscope. We inspect position accuracy, dynamic focus, and dynamic astigmatism, as well as single and multi-pixel lines in thin resist. Beam shape quality is inspected in the corners of the writing field at 6 different beam...... currents between 2 and 60 nA. We use positive-tone resist AR-P6200 (CSAR 62) from All Resist. With our quality control procedure, we routinely write 11 nm lines on a 40 nm pitch, and obtain a field stitching accuracy better than 3 nm and overlay accuracy less than 7 nm....

  13. Effects of gamma and electron beam irradiation on the microbial quality of steamed tofu rolls

    International Nuclear Information System (INIS)

    Jia, Qian; Gao, Meixu; Li, Shurong; Wang, Zhidong

    2013-01-01

    The effectiveness of two kinds of radiation processing, gamma and electron beam (ebeam) irradiation, for the inactivation of Staphylococcus aureus, Salmonella enteritidis and Listeria innocua which were inoculated in pre-sterilised steamed tofu rolls was studied. The corresponding effects of both irradiation types on total bacterial counts (TBCs) in commercial steamed tofu rolls available in the market were also examined. The microbiological results demonstrated that gamma irradiation yielded D 10 values of 0.20, 0.24 and 0.22 kGy for S. aureus, S. enteritidis and L. innocua, respectively. The respective D 10 values for ebeam irradiation were 0.31, 0.35 and 0.27 kGy. Gamma and ebeam irradiation yielded D 10 values of 0.48 and 0.43 kGy for total bacterial counts in commercial steamed tofu rolls, respectively. The results suggest that ebeam irradiation has similar effect on decreasing TBCs in steamed tofu rolls, and gamma irradiation is slightly more effective than ebeam irradiation in reducing the populations of pathogenic bacteria. The observed differences in D 10 -values between them might be due to the significant differences in dose rate applied, and radiation processing of soybean products to improve their microbial quality could be available for other sources of protein. - Highlights: ► Our research material is steamed tofu rolls, a kind of soybean products. ► We compared the effects of gamma ray and electron beam irradiation. ► Total bacterial and three strains of pathogens are studied in our research. ► We reported electron beam has similar decontamination effect as gamma ray. ► Radiation processing of soybean products to improve their microbial quality could be available for other sources of protein.

  14. Evaluation of the Beam Quality of Intraoral X-ray Equipment using Intraoral Standard Films

    International Nuclear Information System (INIS)

    Lee, Sang Sub; Kwon, Hyok Rak; Sim, Woo Hyoun; Oh, Seung Hyoun; Lee, Ji Youn; Jeon, Kug Jin; Kim, Kee Deog; Park, Chang Seo

    2000-01-01

    This study was to evaluate the beam quality of intraoral X-ray equipment used at Yonsei University Dental Hospital (YUDH) using the half value layer (HVL) and the characteristic curve of intraoral standard X-ray film. The study was done using the intraoral X-ray equipment used at each clinical department at YUDH. Aluminum filter was used to determine the HVL. Intraoral standard film was used to get the characteristic curve of each intraoral X-ray equipment. Most of the HVLs of intraoral X-ray equipment were higher than the least recommended thickness, but the REX 601 model used at the operative dentistry department and the X-707 model used at the pediatric dentistry department had HVLs lower than the recommended thickness. The slopes of the characteristic curves of films taken using the PANPAS 601 model and REX 601 model at operative dentistry department, the X-70S model of prosthodontic dentistry department, and the REX 601 model at the student clinic were relatively low. HVL and the characteristic curve of X-ray film can be used to evaluate the beam quality of intraoral X-ray equipment. In order to get the best X-ray films with the least radiation exposure to patients and best diagnostic information in clinical dentistry, X-ray equipment should be managed in the planned and organized fashion.

  15. Quality of working life of nurses and its related factors.

    Science.gov (United States)

    Moradi, Tayebeh; Maghaminejad, Farzaneh; Azizi-Fini, Ismail

    2014-06-01

    Nurses as the largest group of health care providers should enjoy a satisfactory quality of working life to be able to provide quality care to their patients. Therefore, attention should be paid to the nurses' working life. This study aimed to investigate the quality of nurses' working life in Kashans' hospitals during 2012. This cross-sectional study was conducted on 200 nurses during 2012. The data-gathering instrument consisted of two parts. The first part consisted of questions on demographic information and the second part was the Walton's quality of work life questionnaire. Data were analyzed using the SPSS software. For statistical analysis T test and one way ANOVA were used. The results of the study showed that 60% of nurses reported that they had moderate level of quality of working life while 37.1% and 2% had undesirable and good quality of working life, respectively. Nurses with associate degrees reported a better quality of working life than others. A significant relationship was found between variables such as education level, work experience, and type of hospital with quality of working life score (P quality of working life score of nurses with employment status (P = 0.061), salary (P = 0.052), age, gender and marital status (P > 0.05). Nurses' quality of work life was at the moderate level. As quality of work life has an important impact on attracting and retaining employees, it is necessary to pay more attention to the nurses' quality of work life and its affecting factors.

  16. Modeling silicon diode energy response factors for use in therapeutic photon beams.

    Science.gov (United States)

    Eklund, Karin; Ahnesjö, Anders

    2009-10-21

    Silicon diodes have good spatial resolution, which makes them advantageous over ionization chambers for dosimetry in fields with high dose gradients. However, silicon diodes overrespond to low-energy photons, that are more abundant in scatter which increase with large fields and larger depths. We present a cavity-theory-based model for a general response function for silicon detectors at arbitrary positions within photon fields. The model uses photon and electron spectra calculated from fluence pencil kernels. The incident photons are treated according to their energy through a bipartition of the primary beam photon spectrum into low- and high-energy components. Primary electrons from the high-energy component are treated according to Spencer-Attix cavity theory. Low-energy primary photons together with all scattered photons are treated according to large cavity theory supplemented with an energy-dependent factor K(E) to compensate for energy variations in the electron equilibrium. The depth variation of the response for an unshielded silicon detector has been calculated for 5 x 5 cm(2), 10 x 10 cm(2) and 20 x 20 cm(2) fields in 6 and 15 MV beams and compared with measurements showing that our model calculates response factors with deviations less than 0.6%. An alternative method is also proposed, where we show that one can use a correlation with the scatter factor to determine the detector response of silicon diodes with an error of less than 3% in 6 MV and 15 MV photon beams.

  17. Modeling silicon diode energy response factors for use in therapeutic photon beams

    International Nuclear Information System (INIS)

    Eklund, Karin; Ahnesjoe, Anders

    2009-01-01

    Silicon diodes have good spatial resolution, which makes them advantageous over ionization chambers for dosimetry in fields with high dose gradients. However, silicon diodes overrespond to low-energy photons, that are more abundant in scatter which increase with large fields and larger depths. We present a cavity-theory-based model for a general response function for silicon detectors at arbitrary positions within photon fields. The model uses photon and electron spectra calculated from fluence pencil kernels. The incident photons are treated according to their energy through a bipartition of the primary beam photon spectrum into low- and high-energy components. Primary electrons from the high-energy component are treated according to Spencer-Attix cavity theory. Low-energy primary photons together with all scattered photons are treated according to large cavity theory supplemented with an energy-dependent factor K(E) to compensate for energy variations in the electron equilibrium. The depth variation of the response for an unshielded silicon detector has been calculated for 5 x 5 cm 2 , 10 x 10 cm 2 and 20 x 20 cm 2 fields in 6 and 15 MV beams and compared with measurements showing that our model calculates response factors with deviations less than 0.6%. An alternative method is also proposed, where we show that one can use a correlation with the scatter factor to determine the detector response of silicon diodes with an error of less than 3% in 6 MV and 15 MV photon beams.

  18. Quality assurance (QA) program in BNCT. RBE of 7 NCT beams for intestinal crypt regeneration in mice

    International Nuclear Information System (INIS)

    John, Gueulette; De Coster, Blanche-Marie; Wambersie, Andre; Gregoire, Vincent; Rasmussen, Finn S.; Auterinen, Iiro; Binns, Peter; Blaumann, Herman; Matsumura, Akira; Liu Hongming

    2006-01-01

    The epithermal neutron beams presently used for Neutron Capture Therapy (NCT) differ substantially in their composition (relative contribution of the different dose components to the total dose), in their dose rate (depending on the power of the reactor) as well as in their general feature (e.g. beam delivery system). Each of these elements might alter significantly the biological effectiveness of the beams. Therefore, the Relative Biological Effectiveness (RBE) of 7 NCT beams was intercompared, for a reference biological system (crypt regeneration in mice) and under well-defined irradiation conditions. This type of experiments - which should facilitate the exchange of radiobiological/clinical information - should take part of the Quality Assurance (QA) procedure of all NCT beams. (author)

  19. Comparison of the effects of gamma ray and e-beam irradiation on the quality of minced beef during storage

    International Nuclear Information System (INIS)

    Park, Jae Nam; Han, In Jun; Kim, Wang Geun; Song, Beom Seok; Kim, Jae Hun; Choi, Jong Il; Yoon, Yo Han; Byun, Myung Woo; Hwang, Han Joon; Lee, Ju Woon; Park, Jin Gyu

    2009-01-01

    This study was conducted to compare the microbiological and physicochemical qualities of minced beef irradiated with gamma ray of e-beam at the absorbed doses from 5 to 20 kGy. The total bacterial counts of minced beef were decreased depending upon the irradiation doses, but sterilizing effect of gamma irradiation was higher than that of e-beam irradiation. The contents of malondialdegyde of minced beef were increased depending upon irradiation doses as well as storage periods (p< 0.05). Volatile basic nitrogen in minced beef was constantly increased during storage, but the increasing rate were retarded by irradiation. The hunter's color values(L*, a* and b*) of gamma or e-beam irradiated minced beef were decreased as irradiation dose increasing. Meanwhile, the quality changes of gamma irradiated samples were faster than e-beam irradiated samples

  20. Investigation on the Quality Factor Limit of the (111 Silicon Based Disk Resonator

    Directory of Open Access Journals (Sweden)

    Xin Zhou

    2018-01-01

    Full Text Available Quality factor is one of the most important parameters for a MEMS resonator. Most MEMS resonators are dominated by thermoelastic dissipation (TED. This paper demonstrates that the TED in a disk resonator that is made of (111 single-crystal silicon is surpassed by clamping loss. The stiffness-mass decoupling design method, combined with reducing the beam width, was used to engineer high QTED. Experiments show that Q of the (111 disk resonator have an upper boundary that is determined by the clamping loss caused by the unbalanced out-of-plane displacement. The origin of the out-of-plane displacement is explained by theory and simulation.

  1. SU-F-T-338: Flattening Filter Free Photon Beams Can Achieve the Same Plan Quality as Conventional Flattened Beams for Prostate Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kolar, M; Szwedowski, R; Greskovich, J; Xia, P [Cleveland Clinic, Cleveland, OH (United States)

    2016-06-15

    Purpose: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. Methods: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFF plan. Each plan was prescribed so that at least 95% of the PTV received the prescription dose. The following dosimetric endpoints were evaluated: volume receiving 78Gy (V78) of the CTV and PTV, PTV conformality index (CI, ratio of prescription isodose volume to the PTV volume), bladder volume receiving 70Gy (V70) and 60Gy (V60), rectum volume receiving 70Gy (V70) and 50Gy (V50), dose to 10cc of the rectum, and volume of both femoral heads receiving 50Gy (V50). Total monitor units for each plan were recorded. Results: No significant difference was found for all dosimetric endpoints between all plans (p>0.05). Compared to the 6MV plans, monitor units were higher with the double arc 10MV FFF plans and lower with the single arc 10MV FFF plans, 29% and 4% respectively. Conclusion: Both single arc and double arc 10MV FFF VMAT can achieve equivalent plan quality as 6MV flat beam double arc treatment plans. With the gantry speed restriction, a high dose rate of 2400MU/min may allow the optimizer to use more MUs than actually needed. Single arc 10MV FFF VMAT plans are a reasonable alternative to double arc 6MV flat beam VMAT plans.

  2. SU-F-T-338: Flattening Filter Free Photon Beams Can Achieve the Same Plan Quality as Conventional Flattened Beams for Prostate Radiotherapy

    International Nuclear Information System (INIS)

    Kolar, M; Szwedowski, R; Greskovich, J; Xia, P

    2016-01-01

    Purpose: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. Methods: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFF plan. Each plan was prescribed so that at least 95% of the PTV received the prescription dose. The following dosimetric endpoints were evaluated: volume receiving 78Gy (V78) of the CTV and PTV, PTV conformality index (CI, ratio of prescription isodose volume to the PTV volume), bladder volume receiving 70Gy (V70) and 60Gy (V60), rectum volume receiving 70Gy (V70) and 50Gy (V50), dose to 10cc of the rectum, and volume of both femoral heads receiving 50Gy (V50). Total monitor units for each plan were recorded. Results: No significant difference was found for all dosimetric endpoints between all plans (p>0.05). Compared to the 6MV plans, monitor units were higher with the double arc 10MV FFF plans and lower with the single arc 10MV FFF plans, 29% and 4% respectively. Conclusion: Both single arc and double arc 10MV FFF VMAT can achieve equivalent plan quality as 6MV flat beam double arc treatment plans. With the gantry speed restriction, a high dose rate of 2400MU/min may allow the optimizer to use more MUs than actually needed. Single arc 10MV FFF VMAT plans are a reasonable alternative to double arc 6MV flat beam VMAT plans.

  3. Snacking patterns, diet quality, and cardiovascular risk factors in adults

    Science.gov (United States)

    The relationship of snacking patterns on nutrient intake and cardiovascular risk factors in adults is unknown. The aim of this study was to examine the associations of snacking patterns with nutrient intake, diet quality, and a selection of cardiovascular risk factors in adults participating in the ...

  4. Improving the beam quality of the neutron radiography facility using the SLOWPOKE-2 at the Royal Military College of Canada

    International Nuclear Information System (INIS)

    Lewis, W.J.; Bennett, L.G.I.; Teshima, P.

    1996-01-01

    At the SLOWPOKE-2 Facility at the Royal Military College of Canada, a neutron radiography facility has been designed and installed, and the beam quality has been improved by performing a series of radiographs using American standard for testing and materials (ASTM) E 545 indicators. Other means of determining the progress such as bubble detectors and activation foils were used. Modifications to the nosepiece of the beam tube including shielding and linings for fast neutron and gamma radiation were made. (orig.)

  5. Quality assurance in proton beam therapy using a plastic scintillator and a commercially available digital camera.

    Science.gov (United States)

    Almurayshid, Mansour; Helo, Yusuf; Kacperek, Andrzej; Griffiths, Jennifer; Hebden, Jem; Gibson, Adam

    2017-09-01

    In this article, we evaluate a plastic scintillation detector system for quality assurance in proton therapy using a BC-408 plastic scintillator, a commercial camera, and a computer. The basic characteristics of the system were assessed in a series of proton irradiations. The reproducibility and response to changes of dose, dose-rate, and proton energy were determined. Photographs of the scintillation light distributions were acquired, and compared with Geant4 Monte Carlo simulations and with depth-dose curves measured with an ionization chamber. A quenching effect was observed at the Bragg peak of the 60 MeV proton beam where less light was produced than expected. We developed an approach using Birks equation to correct for this quenching. We simulated the linear energy transfer (LET) as a function of depth in Geant4 and found Birks constant by comparing the calculated LET and measured scintillation light distribution. We then used the derived value of Birks constant to correct the measured scintillation light distribution for quenching using Geant4. The corrected light output from the scintillator increased linearly with dose. The system is stable and offers short-term reproducibility to within 0.80%. No dose rate dependency was observed in this work. This approach offers an effective way to correct for quenching, and could provide a method for rapid, convenient, routine quality assurance for clinical proton beams. Furthermore, the system has the advantage of providing 2D visualization of individual radiation fields, with potential application for quality assurance of complex, time-varying fields. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  6. DETERMINANT FACTORS OF FINANCIAL REPORTING QUALITY AND ECONOMIC CONSEQUENCES

    Directory of Open Access Journals (Sweden)

    Zaenal Fanani

    2017-03-01

    Full Text Available The aim of this research was to prove empirically the determining factors that influence the quality of financialreporting and the economic consequences, and there were influence differences of quality attributes of financialreporting to the economic consequences. The research samples were taken by purposive sampling so it obtained141 listed manufacturing businesses from 2001 to 2006. The research used four data analysis technique:auxiliary regression R2, confirmatory factor analysis, simple regression, and multiple regressions. The resultsshowed seven attributes, there were five attributes that gave contribution for financial reporting quality namelyaccrual quality, predictability, smoothness, relevance value, and conservatism while the persistence and timelinessgave small contribution. The five attributes were also different each other. From the thirteen determiningfactors, it showed nine factors that produced significant influences namely operation cycle, sales volatility,firm size, firm age, loss proportion, leverage, environmental risk, institutional ownership, market concentration,and auditor quality, while the other three, they were liquidity, managerial ownership, and investmentgrowth that were not significant. Testing results of economic consequences of quality of financial reportingshowed that the quality of factorial financial reporting influenced negatively and significantly toward informationasymmetry.

  7. Studying wedge factors and beam profiles for physical and enhanced dynamic wedges

    Directory of Open Access Journals (Sweden)

    Ahmad Misbah

    2010-01-01

    Full Text Available This study was designed to investigate variation in Varian′s Physical and Enhanced Dynamic Wedge Factors (WF as a function of depth and field size. The profiles for physical wedges (PWs and enhanced dynamic wedges (EDWs were also measured using LDA-99 array and compared for confirmation of EDW angles at different depths and field sizes. WF measurements were performed in water phantom using cylindrical 0.66 cc ionization chamber. WF was measured by taking the ratio of wedge and open field ionization data. A normalized wedge factor (NWF was introduced to circumvent large differences between wedge factors for different wedge angles. A strong linear dependence of PW Factor (PWF with depth was observed. Maximum variation of 8.9% and 4.1% was observed for 60° PW with depth at 6 and 15 MV beams respectively. The variation in EDW Factor (EDWF with depth was almost negligible and less than two per cent. The highest variation in PWF as a function of field size was 4.1% and 3.4% for thicker wedge (60° at 6 and 15 MV beams respectively and decreases with decreasing wedge angle. EDWF shows strong field size dependence and significant variation was observed for all wedges at both photon energies. Differences in profiles between PW and EDW were observed on toe and heel sides. These differences were dominant for larger fields, shallow depths, thicker wedges and low energy beam. The study indicated that ignoring depth and field size dependence of WF may result in under/over dose to the patient especially doing manual point dose calculation.

  8. Quality control methodology and implementation of X-radiation standards beams, mammography level, following the standard IEC 61267

    International Nuclear Information System (INIS)

    Correa, Eduardo de Lima

    2010-01-01

    In this work it was developed and applied a quality control program of the X radiation system (160 kV, constant potential, target of tungsten) of the Calibration Laboratory of IPEN(LCI) in the energy range relative to mammography beams (from 25 kV to 35 kV). The X radiation standards beams, level mammography, using molybdenum and aluminum as additional filtration, were established after the application of this quality control program following national and international recommendations. The reference ionization chamber has traceability to PTB and was regularly submitted to quality control tests for evaluation and analysis of its performance. The radiation qualities emerging from the X-radiation assembly (RQR-M), based on a phantom made up of an aluminum added filter (RQA-M), narrow beam condition (RQN-M) and broad beam condition (RQB-M), following the recommendations of the international standard IEC 61267 (2005) and the IAEA code of practice, TRS 457 (2007) were established. For the implantation of RQN-M and RQB-M radiation qualities, two mammography phantoms were developed. The half-value layers found are those presented by the German primary laboratory PTB, and varied from 0.35 to 1.21 mm Al. The air kerma rates were obtained for all the 15 implanted qualities. (author)

  9. High quality proton beams from hybrid integrated laser-driven ion acceleration systems

    Energy Technology Data Exchange (ETDEWEB)

    Sinigardi, Stefano, E-mail: sinigardi@bo.infn.it [Dipartimento di Fisica e Astronomia, Università di Bologna and INFN Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale [Dipartimento di Fisica e Astronomia, Università di Bologna and INFN Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Giove, Dario; De Martinis, Carlo [Dipartimento di Fisica, Università di Milano and INFN Sezione di Milano, Via F.lli Cervi 201, I-20090 Segrate (Italy); Bolton, Paul R. [Kansai Photon Science Institute (JAEA), Umemidai 8-1-7, Kizugawa-shi, Kyoto 619-0215 (Japan)

    2014-03-11

    We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15M€. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments.

  10. High quality proton beams from hybrid integrated laser-driven ion acceleration systems

    Science.gov (United States)

    Sinigardi, Stefano; Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale; Giove, Dario; De Martinis, Carlo; Bolton, Paul R.

    2014-03-01

    We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15 M €. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments.

  11. High quality proton beams from hybrid integrated laser-driven ion acceleration systems

    International Nuclear Information System (INIS)

    Sinigardi, Stefano; Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale; Giove, Dario; De Martinis, Carlo; Bolton, Paul R.

    2014-01-01

    We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15M€. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments

  12. Electron beam irradiation of sun-dried apricots for quality maintenance

    International Nuclear Information System (INIS)

    Wei, Ming; Zhou, Linyan; Song, Hongbo; Yi, Jianyong; Wu, Bin; Li, Yaru; Zhang, Le; Che, Fengbin; Wang, Zhidong; Gao, Meixu

    2014-01-01

    The chemical, sensory, and microbial quality parameters of electron beam (EB)-irradiated and non-irradiated sun-dried apricots were periodically evaluated to optimize the EB irradiation of sun-dried apricots for quality maintenance. The sun-dried apricots were treated with 1.0, 2.0, 3.0, 4.0, and 5.0 kGy of EB and subsequently stored at ambient temperature. EB treatment at 1.0–3.0 kGy proved to be beneficial for retaining high levels of β-carotene, ascorbic acid, titratable acidity, total sugars, and color without any significant effect on sensory properties. Doses of 1.0–3.0 kGy retained the β-carotene content of sun-dried apricots to 8.21%, 9.27%, and 10.43% compared with 6.09% in control samples after 10 months of storage. After 10 months of storage, the maximum losses of ascorbic acid were 37.8% in control samples and 35.5% in 3.0 kGy-irradiated samples. Titratable acidity and total sugars were significantly enhanced immediately after 1.0–3.0 kGy irradiation treatment, and both parameters showed no significant change after 10 months of storage. Samples subjected to EB treatment at 3.0 kGy maintained a high overall acceptability of sun-dried apricots. Decreased number of viable microorganisms to below detection limits were observed after 3.0 kGy irradiation, and compared with the control, the logarithmic reductions after 10 months of storage were 0.98 for yeast and mold count, as well as 1.71 for bacterial count. - Highlights: • Electron beam irradiation was used for sun-dried apricots quality maintenance. • The chemical, sensory, and microbial quality parameters of apricots were evaluated. • 1.0–3.0 kGy proved to be beneficial for retaining high levels of apricots quality. • 3.0 kGy of irradiation maintained a high overall acceptability of sun-dried apricots. • 3.0 kGy of irradiation reduced the viable microorganisms to below detection limits

  13. Application of high quality antiproton beam to study charmonium and exotics above DD-bar threshold

    International Nuclear Information System (INIS)

    Barabanov, M.Y.; Vodopyanov, A.S.

    2014-01-01

    The spectroscopy of charmonium and exotic states with hidden charm is discussed. It is a good testing tool for theories of strong interactions including QCD in both perturbative and non-perturbative regime, lattice QCD, potential models and phenomenological models. An elaborated analysis of charmonium and charmed hybrid spectrum is given, and attempts to interpret recent experimental data in the above DD-bar threshold region are considered. Experiments using antiproton beam take advantage of the intensive production of particle-antiparticle pairs in antiproton-proton annihilations. Experimental data from different collaboration are analyzed with special attention given to new states with hidden charm that were discovered recently. Some of these states can be interpreted as higher-laying S, P and D wave charmonium states. But much more data on different decay modes are needed before firmer conclusions can be made. These data can be derived directly from the experiments using high quality antiproton beam with momentum up to 15 GeV/c. (authors)

  14. Applications of factor analysis to electron and ion beam surface techniques

    International Nuclear Information System (INIS)

    Solomon, J.S.

    1987-01-01

    Factor analysis, a mathematical technique for extracting chemical information from matrices of data, is used to enhance Auger electron spectroscopy (AES), core level electron energy loss spectroscopy (EELS), ion scattering spectroscopy (ISS), and secondary ion mass spectroscopy (SIMS) in studies of interfaces, thin films, and surfaces. Several examples of factor analysis enhancement of chemical bonding variations in thin films and at interfaces studied with AES and SIMS are presented. Factor analysis is also shown to be of great benefit in quantifying electron and ion beam doses required to induce surface damage. Finally, examples are presented of the use of factor analysis to reconstruct elemental profiles when peaks of interest overlap each other during the course of depth profile analysis. (author)

  15. Factors affecting quality of life in Hungarian adults with epilepsy

    DEFF Research Database (Denmark)

    Kováts, Daniella; Császár, Noémi; Haller, József

    2017-01-01

    perception (Illness Perception Questionnaire, IPQ) was also studied. RESULTS: The four measures correlated highly significantly. In addition, the predictive power of factors was comparable with the four inventories as evaluated by Multiple Regression. Factors explained 52%, 41%, 63% and 46% in the variance......PURPOSE: We investigated the impact of 19 factors on life quality in Hungarian patients with epilepsy. Wellbeing was evaluated by several inventories to investigate the impact of factors in more detail. METHODS: A cross-sectional study was performed in 170 patients. Wellbeing was evaluated...... as influencing life quality. This appears to be the first study that analyses the factors that influence illness perception in epilepsy patients, and suggests that the IPQ may become a valuable tool in epilepsy research....

  16. Quality control in cone-beam computed tomography (CBCT) EFOMP-ESTRO-IAEA protocol (summary report).

    Science.gov (United States)

    de Las Heras Gala, Hugo; Torresin, Alberto; Dasu, Alexandru; Rampado, Osvaldo; Delis, Harry; Hernández Girón, Irene; Theodorakou, Chrysoula; Andersson, Jonas; Holroyd, John; Nilsson, Mats; Edyvean, Sue; Gershan, Vesna; Hadid-Beurrier, Lama; Hoog, Christopher; Delpon, Gregory; Sancho Kolster, Ismael; Peterlin, Primož; Garayoa Roca, Julia; Caprile, Paola; Zervides, Costas

    2017-07-01

    The aim of the guideline presented in this article is to unify the test parameters for image quality evaluation and radiation output in all types of cone-beam computed tomography (CBCT) systems. The applications of CBCT spread over dental and interventional radiology, guided surgery and radiotherapy. The chosen tests provide the means to objectively evaluate the performance and monitor the constancy of the imaging chain. Experience from all involved associations has been collected to achieve a consensus that is rigorous and helpful for the practice. The guideline recommends to assess image quality in terms of uniformity, geometrical precision, voxel density values (or Hounsfield units where available), noise, low contrast resolution and spatial resolution measurements. These tests usually require the use of a phantom and evaluation software. Radiation output can be determined with a kerma-area product meter attached to the tube case. Alternatively, a solid state dosimeter attached to the flat panel and a simple geometric relationship can be used to calculate the dose to the isocentre. Summary tables including action levels and recommended frequencies for each test, as well as relevant references, are provided. If the radiation output or image quality deviates from expected values, or exceeds documented action levels for a given system, a more in depth system analysis (using conventional tests) and corrective maintenance work may be required. Copyright © 2017. Published by Elsevier Ltd.

  17. Effect of electron beam irradiation on quality of fresh chilled pork

    International Nuclear Information System (INIS)

    Shang Yibin; Gao Meixu; Li Shurong; Pei Ying; Wang Zhidong

    2013-01-01

    The effects of electron beam irradiation on nutrient quality, lipid oxidation and sensory quality of fresh chilled pork were investigated. Fresh chilled pork whose fat to muscle ratio was 1 : 6 was grounded and packaged, and then irradiated at doses of 0, 2.0, 3.8, 6.2, 8.3 and 10.5 kGy. The contents of fat andprotein, chromaticity, sensory characteristics, lipid oxidation index of TBARS value, POV, diene value of irradiated and unirradiated samples were measured. The results showed that there were no significant differences (5% level) in content of proteinand fat between irradiated and control samples, but irradiation could significantly increase TBARS value and POV. EB irradiation enhanced the increase of total diene value. The samples treated with 3.8 and 6.2 kGy showed good color during storage. There were no significant differences in sensory characteristics among different EB doses. It is concluded that 4-6 kGy EB irradiation, which is effective for decontamination, shows no significant effect on qualities of fresh chilled pork. (authors)

  18. Bowtie filter and water calibration in the improvement of cone beam CT image quality

    International Nuclear Information System (INIS)

    Li Minghui; Dai Jianrong; Zhang Ke

    2010-01-01

    Objective: To evaluate the improvement of cone beam CT (CBCT) image quality by using bewtie filter (F 1 ) and water calibration. Methods: First the multi-level gain calibration of the detector panel with the method of Cal 2 calibration was performed, and the CT images of CATPHAN503 with F 0 and bowtie filter were collected, respectively. Then the detector panel using water calibration kit was calibrated, and images were acquired again. Finally, the change of image quality after using F 1 and (or) water calibration method was observed. The observed indexes included low contrast visibility, spatial uniformity, ring artifact, spatial resolution and geometric accuracy. Results: Comparing with the traditional combination of F 0 filter and Cal 2 calibration, the combination of bowtie filter F 1 and water calibration improves low contrast visibility by 13.71%, and spatial uniformity by 54. 42%. Water calibration removes ring artifacts effectively. However, none of them improves spatial resolution and geometric accuracy. Conclusions: The combination of F 1 and water calibration improves CBCT image quality effectively. This improvement is aid to the registration of CBCT images and localization images. (authors)

  19. Quality of 'Sharpblue' blueberries after electron beam irradiation

    International Nuclear Information System (INIS)

    Miller, W.R.; McDonald, R.E.; Smittle, B.J.

    1995-01-01

    Freshly harvested 'Sharpblue' blueberries (Vaccinium spp.), a hybrid of complex parentage (Sharpe and Sherman, 1976), were irradiated by electron beam at 0, 0.25, 0.5, 0.75, or 1.0 kGy to determine its effects on condition and quality after treatment and subsequent storage. Berry firmness was not affected by increased doses following 1 or 3 days of storage at 1C, but it declined with higher doses when stored for 7 days at 1C. In general, berry flavor and texture declined as dosage increased; however, neither flavor nor texture were rated unacceptable by a sensory panel. Weight loss, decay, soluble solids concentration, acidity, pH, skin color, or waxy bloom were not affected by dosage or storage

  20. URBAN LANDSCAPE QUALITY AND FACTORS THAT HAVE INFLUENCE ON LANDSCAPE QUALITY IN LATGALE REGION

    OpenAIRE

    Matisovs, Ivars

    2005-01-01

    The paper deals with urban landscape individualities in the cities and towns of Latgale region. Also show facilities and methods of integrated assessment of urban landscape quality. Article provides information about specifics of urban landscape and factors, that have influence on landscape quality. The paper presents the results of Daugavpils and Rēzekne urban landscape quality complex assessment, that have been realised in 2003- 2005. This results don’t establish significant disparities bet...

  1. Updating the tritium quality factor: the argument for conservatism

    International Nuclear Information System (INIS)

    Till, J.E.; Etnier, E.L.; Meyer, H.R.

    1980-01-01

    Estimated doses resulting from tritium releases to the environment are linearly dependent upon the quality factor (Q) chosen for tritium beta radiation. In 1969 the International Commission on Radiological Protection (ICRP) recommended using 1 as the Q for all low energy beta radiation. Considerable improvements have been made in evaluating exposures to tritium at very low dose rates and in refining physiological and biological endpoints since the 1969 ICRP recommendations. This study summarizes recent experiments to determine the relative biological effectiveness of tritium. Based upon our study of published data related to quality factor, its importance in the calculation of dose, and the currently accepted conservative philosophy in radiation protection, it is concluded that a value of 2 would seem to be more defensible for environmental assessments and that a reevaluation of the tritium quality factor by the ICRP is needed

  2. FACTORS DESCRIBING STUDENTS´ PERCEPTION ON EDUCATION QUALITY STANDARDS

    Directory of Open Access Journals (Sweden)

    Lucie Vnoučková

    2017-12-01

    Full Text Available Education quality assurance is the necessity for today’s competitive environment in university education. Quality assurance standards and strategies are being used in most of universities and higher education institutions. But the perception of quality standards is being usually seen from the perspective of a university management. This study aims to analyze and present perceptions of students towards a measurement of education quality standards and to identify significant groups of students according to their preferences in education quality. Students’ questionnaires and focus groups collected the data. Two dimensional and multi-dimensional statistical methods were used to evaluate the results. The outputs show five groups of students based on their perception of the education quality. Examination of students’ interest in specific areas, subjects and courses leads to identification of factors which affect their preferences in education. The paper found five significant groups of perceived quality by students. These are Quality receptionists, Business oriented, Expert innovators, Distance learners and Arrangement oriented. Limit of the study is a narrow focus on one private university. This study may encourage other papers to develop and test further the impact of education quality on students’ preferences for measurable improvements. The paper is an extension of the conference paper presented on ERIE conference 2017.

  3. Project quality management critical success factors for buildings

    CERN Document Server

    Low, Sui Pheng

    2014-01-01

    The book presents the development of the Construction Quality Assessment System (CONQUAS), Singapore’s de facto quality performance measurement system, explains the application of the Quality Management System (QMS) to manage CONQUAS and identifies 33 critical success factors (CSFs) for achieving high CONQUAS scores. Through CONQUAS, the reader benefits from understanding how the Singapore government developed and implemented the first objective system for measuring what many building professionals have perceived to be elusive quality standards in the construction industry. The book presents both the theoretical concepts as well as the practical aspects to achieving strategic Project Quality Management that is anchored on the CSFs to building best practices. To realistically reflect the practical aspects and challenging issues faced by stakeholders in the construction industry, questionnaire surveys were conducted with building professionals to distinguish the importance level and extent of adoption of the ...

  4. Electron fluence correction factors for various materials in clinical electron beams

    International Nuclear Information System (INIS)

    Olivares, M.; Blois, F. de; Podgorsak, E.B.; Seuntjens, J.P.

    2001-01-01

    Relative to solid water, electron fluence correction factors at the depth of dose maximum in bone, lung, aluminum, and copper for nominal electron beam energies of 9 MeV and 15 MeV of the Clinac 18 accelerator have been determined experimentally and by Monte Carlo calculation. Thermoluminescent dosimeters were used to measure depth doses in these materials. The measured relative dose at d max in the various materials versus that of solid water, when irradiated with the same number of monitor units, has been used to calculate the ratio of electron fluence for the various materials to that of solid water. The beams of the Clinac 18 were fully characterized using the EGS4/BEAM system. EGSnrc with the relativistic spin option turned on was used to optimize the primary electron energy at the exit window, and to calculate depth doses in the five phantom materials using the optimized phase-space data. Normalizing all depth doses to the dose maximum in solid water stopping power ratio corrected, measured depth doses and calculated depth doses differ by less than ±1% at the depth of dose maximum and by less than 4% elsewhere. Monte Carlo calculated ratios of doses in each material to dose in LiF were used to convert the TLD measurements at the dose maximum into dose at the center of the TLD in the phantom material. Fluence perturbation correction factors for a LiF TLD at the depth of dose maximum deduced from these calculations amount to less than 1% for 0.15 mm thick TLDs in low Z materials and are between 1% and 3% for TLDs in Al and Cu phantoms. Electron fluence ratios of the studied materials relative to solid water vary between 0.83±0.01 and 1.55±0.02 for materials varying in density from 0.27 g/cm3 (lung) to 8.96 g/cm3 (Cu). The difference in electron fluence ratios derived from measurements and calculations ranges from -1.6% to +0.2% at 9 MeV and from -1.9% to +0.2% at 15 MeV and is not significant at the 1σ level. Excluding the data for Cu, electron fluence

  5. Key factors for a high-quality VR experience

    Science.gov (United States)

    Champel, Mary-Luc; Doré, Renaud; Mollet, Nicolas

    2017-09-01

    For many years, Virtual Reality has been presented as a promising technology that could deliver a truly new experience to users. The media and entertainment industry is now investigating the possibility to offer a video-based VR 360 experience. Nevertheless, there is a substantial risk that VR 360 could have the same fate as 3DTV if it cannot offer more than just being the next fad. The present paper aims at presenting the various quality factors required for a high-quality VR experience. More specifically, this paper will focus on the main three VR quality pillars: visual, audio and immersion.

  6. Direct determination of k Q factors for cylindrical and plane-parallel ionization chambers in high-energy electron beams from 6 MeV to 20 MeV

    Science.gov (United States)

    Krauss, A.; Kapsch, R.-P.

    2018-02-01

    For the ionometric determination of the absorbed dose to water, D w, in high-energy electron beams from a clinical accelerator, beam quality dependent correction factors, k Q, are required. By using a water calorimeter, these factors can be determined experimentally and potentially with lower standard uncertainties than those of the calculated k Q factors, which are tabulated in various dosimetry protocols. However, one of the challenges of water calorimetry in electron beams is the small measurement depths in water, together with the steep dose gradients present especially at lower energies. In this investigation, water calorimetry was implemented in electron beams to determine k Q factors for different types of cylindrical and plane-parallel ionization chambers (NE2561, NE2571, FC65-G, TM34001) in 10 cm  ×  10 cm electron beams from 6 MeV to 20 MeV (corresponding beam quality index R 50 ranging from 1.9 cm to 7.5 cm). The measurements were carried out using the linear accelerator facility of the Physikalisch-Technische Bundesanstalt. Relative standard uncertainties for the k Q factors between 0.50% for the 20 MeV beam and 0.75% for the 6 MeV beam were achieved. For electron energies above 8 MeV, general agreement was found between the relative electron energy dependencies of the k Q factors measured and those derived from the AAPM TG-51 protocol and recent Monte Carlo-based studies, as well as those from other experimental investigations. However, towards lower energies, discrepancies of up to 2.0% occurred for the k Q factors of the TM34001 and the NE2571 chamber.

  7. Direct determination of k Q factors for cylindrical and plane-parallel ionization chambers in high-energy electron beams from 6 MeV to 20 MeV.

    Science.gov (United States)

    Krauss, A; Kapsch, R-P

    2018-02-06

    For the ionometric determination of the absorbed dose to water, D w , in high-energy electron beams from a clinical accelerator, beam quality dependent correction factors, k Q , are required. By using a water calorimeter, these factors can be determined experimentally and potentially with lower standard uncertainties than those of the calculated k Q factors, which are tabulated in various dosimetry protocols. However, one of the challenges of water calorimetry in electron beams is the small measurement depths in water, together with the steep dose gradients present especially at lower energies. In this investigation, water calorimetry was implemented in electron beams to determine k Q factors for different types of cylindrical and plane-parallel ionization chambers (NE2561, NE2571, FC65-G, TM34001) in 10 cm  ×  10 cm electron beams from 6 MeV to 20 MeV (corresponding beam quality index R 50 ranging from 1.9 cm to 7.5 cm). The measurements were carried out using the linear accelerator facility of the Physikalisch-Technische Bundesanstalt. Relative standard uncertainties for the k Q factors between 0.50% for the 20 MeV beam and 0.75% for the 6 MeV beam were achieved. For electron energies above 8 MeV, general agreement was found between the relative electron energy dependencies of the k Q factors measured and those derived from the AAPM TG-51 protocol and recent Monte Carlo-based studies, as well as those from other experimental investigations. However, towards lower energies, discrepancies of up to 2.0% occurred for the k Q factors of the TM34001 and the NE2571 chamber.

  8. Factors associated with diet quality of older adults

    Directory of Open Access Journals (Sweden)

    Tatiana Império de FREITAS

    Full Text Available ABSTRACT Objective Evaluate the factors associated with diet quality of older adults from the city of São Caetano do Sul, São Paulo, Brazil. Methods A cross-sectional study was carried out on a sample of 295 older adults receiving care in health care units in São Caetano do Sul. Diet quality was assessed using the Brazilian Healthy Eating Index. The associations between the diet quality mean score and the socio-demographic, economic, and anthropometric characteristics and lifestyle and health conditions were verified using multiple linear regression. Results Lower diet quality mean score were associated with the variables: marital status (widowed or separated (β=-2.02; p=0.047, retired (β=-4.24; p=0.034, and smoking (β=-8.06; p=0.001; whereas higher diet quality mean score were associated with higher education level (9 years or more (β=3.49; p=0.013. Conclusion Individuals with higher education level had better diet quality, and those who were widowed or separated, retired, and smokers had worse diet quality indicating that socio-demographic, economic, and lifestyle are factors that can influence food choice of older adults.

  9. Modeling of transmission and DLG factors for a TrueBeam STX; Modelagem dos fatores de transmissão e DLG para um TrueBeam STX

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Laís B.; Pavan, Guilherme A.; Camargo, André V.; Santoni, Letícia M.; Silva, Diego C. S. A. [Hospital de Câncer de Barretos, SP (Brazil)

    2017-07-01

    For the rounded leaf-end Multi Leaf Collimator (MLC), the Eclipse planning system (Varian) requires the measurement of the Transmission Factor (FT) and Dosimetric Leaf Gap (DLG) for Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT). The use of these factors obtained by the methodology proposed by Varian may not guarantee the best agreement in quality assurance (QA) of patients, while the modeling of these factors makes it possible to obtain an 'optimal' value by reducing the differences between doses measured / calculated. The objective of this work was to measure the FT and DLG of a TrueBeam accelerator (TB) with different setups and detectors, model these parameters and validate the results applying the AAPM-TG119 methodology using the Portal Dosimetry (PD) system. To obtain FT and DLG (6MV, 6FFF, 10MV and 10FFF), DICOM plans supplied by Varian and Farmer ionization chamber and CC13 were used in different setups. For the modeling, the dose measured with the Farmer chamber was initially used in VMAT plans for prostate and head and neck. From the obtained data, interactively the values of the FT and DLG were altered by searching for a higher oil index (> 95%) in the 1% 1mm criterion using the PD. Finally, all planning of TG119 with IMRT and VMAT were measured using PD. The measured values were: 6X [(FT = 1.1% / 1.0%) (DLG = 0.044cm / 0.12cm)], 10X [(FT = 1.3% / 1.3% (FT = 0.93% / 0.4%) (DLG = 0.036cm / 0.05cm)], 10FFF [(FT = 1.14% / 1.05%) (DLG = 0.048 Cm / 0.05cm)]. The mean acceptance percentages for the gamma criterion 1% 1mm of the TG119 schedules with VMAT / IMRT after modeling were 6X: 96% / 76%; 10X: 98% / 95%; 6FFF: 97% / 87%; 10FFF: 97% / 82%. The modeling of FT and DLG is useful to improve the accuracy of patient quality assurance, but the choice of detector and the technique used (VMAT or IMRT) are determinant and lead to different results. A balance should be found according to the routine of the

  10. A feasibility study of Dynamic Phantom scanner for quality assurance of photon beam profiles at various gantry angles.

    Science.gov (United States)

    Zhang, Yunkai; Hsi, Wen C; Chu, James C H; Bernard, Damian B; Abrams, Ross A

    2005-01-01

    The effect of gantry rotation on beam profiles of photon and electron beams is an important issue in quality assurance for radiotherapy. To address variations in the profiles of photon and electron beams at different gantry angles, a Dynamic Phantom scanner composed of a 20 x 12 x 6 cm3 scanning Lucite block was designed as a cross-beam-profile scanner. To our knowledge, differences between scanned profiles acquired at different gantry angles with a small size Lucite block and those acquired a full-size (60 x 60 x 50 cm3) water phantom have not been previously investigated. We therefore performed a feasibility study for a first prototype Dynamic Phantom scanner without a gantry attachment mount. Radiation beams from a Varian LINAC 21EX and 2100C were used. Photon beams (6 MV and 18 MV) were shaped by either collimator jaws or a Varian 120 Multileaf (MLC) collimator, and electron beams (6 MeV, 12 MeV, and 20 MeV) were shaped by a treatment cone. To investigate the effect on profiles by using a Lucite block, a quantitative comparison of scanned profiles with the Dynamic Phantom and a full-size water phantom was first performed at a 0 degrees gantry angle for both photon and electron beams. For photon beam profiles defined by jaws at 1.0 cm and 5.0 cm depths of Lucite (i.e., at 1.1 cm and 5.7 cm depth of water), a good agreement (less than 1% variation) inside the field edge was observed between profiles scanned with the Dynamic Phantom and with a water phantom. The use of Lucite in the Dynamic Phantom resulted in reduced penumbra width (about 0.5 mm out of 5 mm to 8mm) and reduced (1% to 2%) scatter dose beyond the field edges for both 6 MV and 18 MV beams, compared with the water phantom scanner. For profiles of the MLC-shaped 6 MV photon beam, a similar agreement was observed. For profiles of electron beams scanned at 2.9 cm depth of Lucite (i.e., at 3.3 cm depth of water), larger disagreements in profiles (3% to 4%) and penumbra width (3 mm to 4 mm out of 12 mm

  11. Variation in Adherence to External Beam Radiotherapy Quality Measures Among Elderly Men With Localized Prostate Cancer

    International Nuclear Information System (INIS)

    Bekelman, Justin E.; Zelefsky, Michael J.; Jang, Thomas L.; Basch, Ethan M.; Schrag, Deborah

    2007-01-01

    Purpose: To characterize the variation in adherence to quality measures of external beam radiotherapy (EBRT) for localized prostate cancer and its relation to patient and provider characteristics in a population-based, representative sample of U.S. men. Methods and Materials: We evaluated EBRT quality measures proposed by a RAND expert panel of physicians among men aged ≥65 years diagnosed between 2000 and 2002 with localized prostate cancer and treated with primary EBRT using data from the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare program. We assessed the adherence to five EBRT quality measures that were amenable to analysis using SEER-Medicare data: (1) use of conformal RT planning; (2) use of high-energy (>10-MV) photons; (3) use of custom immobilization; (4) completion of two follow-up visits with a radiation oncologist in the year after therapy; and (5) radiation oncologist board certification. Results: Of the 11,674 patients, 85% had received conformal RT planning, 75% had received high-energy photons, and 97% had received custom immobilization. One-third of patients had completed two follow-up visits with a radiation oncologist, although 91% had at least one visit with a urologist or radiation oncologist. Most patients (85%) had been treated by a board-certified radiation oncologist. Conclusions: The overall high adherence to EBRT quality measures masked substantial variation in geography, socioeconomic status in the area of residence, and teaching affiliation of the RT facility. Future research should examine the reasons for the variations in these measures and whether the variation is associated with important clinical outcomes

  12. IEC 61267: Feasibility of type 1100 aluminium and a copper/aluminium combination for RQA beam qualities.

    Science.gov (United States)

    Leong, David L; Rainford, Louise; Zhao, Wei; Brennan, Patrick C

    2016-01-01

    In the course of performance acceptance testing, benchmarking or quality control of X-ray imaging systems, it is sometimes necessary to harden the X-ray beam spectrum. IEC 61267 specifies materials and methods to accomplish beam hardening and, unfortunately, requires the use of 99.9% pure aluminium (Alloy 1190) for the RQA beam quality, which is expensive and difficult to obtain. Less expensive and more readily available filters, such as Alloy 1100 (99.0% pure) aluminium and copper/aluminium combinations, have been used clinically to produce RQA series without rigorous scientific investigation to support their use. In this paper, simulation and experimental methods are developed to determine the differences in beam quality using Alloy 1190 and Alloy 1100. Additional simulation investigated copper/aluminium combinations to produce RQA5 and outputs from this simulation are verified with laboratory tests using different filter samples. The results of the study demonstrate that although Alloy 1100 produces a harder beam spectrum compared to Alloy 1190, it is a reasonable substitute. A combination filter of 0.5 mm copper and 2 mm aluminium produced a spectrum closer to that of Alloy 1190 than Alloy 1100 with the added benefits of lower exposures and lower batch variability. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  13. Design of a Highly Stable, High-Conversion-Efficiency, Optical Parametric Chirped-Pulse Amplification System with Good Beam Quality

    International Nuclear Information System (INIS)

    Guardalben, M.J.; Keegan, J.; Waxer, L.J.; Bagnoud, V.; Begishev, I.A.; Puth, J.; Zuegel, J.D.

    2003-01-01

    OAK B204 An optical parametric chirped-pulse amplifier (OPCPA) design that provides 40% pump-to-signal conversion efficiency and over-500-mJ signal energy at 1054 nm for front-end injection into a Nd:glass amplifier chain is presented. This OPCPA system is currently being built as the prototype front end for the OMEGA EP (extended performance) laser system at the University of Rochester's Laboratory for Laser Energetics. Using a three-dimensional spatial and temporal numerical model, several design considerations necessary to achieve high conversion efficiency, good output stability, and good beam quality are discussed. The dependence of OPCPA output on the pump beam's spatiotemporal shape and the relative size of seed and pump beams is described. This includes the effects of pump intensity modulation and pump-signal walk-off. The trade-off among efficiency, stability, and low output beam intensity modulation is discussed

  14. An examination of human factors in external beam radiation therapy: Findings and implications

    International Nuclear Information System (INIS)

    Henriksen, K.; Kaye, R.D.; Jones, R.E. Jr.; Morisseau, D.S.; Persensky, J.J.

    1994-01-01

    To better understand the contributing factors to human error in external beam radiation therapy, the US Nuclear Regulatory Commission has undertaken a series of human factors evaluations. A team of human factors specialists, assisted by a panel of radiation oncologists, medical physicists, and radiation technologists, conducted visits to 24 radiation oncology departments at community hospitals, university centers, and free-standing clinics. A function and task analysis was initially performed to guide subsequent evaluations in the areas of human-system interfaces, procedures, training and qualifications, and organizational policies and practices. Representative findings and implications for improvement are discussed within the context of a dynamic model which holds that misadministration likely results from the unanticipated interaction of several necessary but singly insufficient conditions

  15. Coupling of high-quality-factor optical resonators

    International Nuclear Information System (INIS)

    Salzenstein, Patrice; Henriet, Rémi; Coillet, Aurélien; Chembo, Yanne K; Mortier, Michel; Sérier-Brault, Hélène; Rasoloniaina, Alphonse; Dumeige, Yannick; Féron, Patrice

    2013-01-01

    We improve theoretically and experimentally the problem of the coupling between a high Q-factor resonator and its external coupler. We have observed oscillations of ringing induced by the sweeping of the excitation frequency of an active microsphere. Thanks to this approach, the quality factor of an optical resonator was measured and we obtained Q = 5.8 × 10 8 . (paper)

  16. Quantification frameworks and their application for evaluating the software quality factor using quality characteristic value

    International Nuclear Information System (INIS)

    Kim, C.; Chung, C.H.; Won-Ahn, K.

    2004-01-01

    Many problems, related with safety, frequently occur because Digital Instrument and Control Systems are widely used and expanding their ranges to many applications in Nuclear Power Plants. It, however, does not hold a general position to estimate an appropriate software quality. Thus, the Quality Characteristic Value, a software quality factor through each software life cycle, is suggested in this paper. The Quality Characteristic Value is obtained as following procedure: 1) Scoring Quality Characteristic Factors (especially correctness, traceability, completeness, and understandability) onto Software Verification and Validation results, 2) Deriving the diamond-shaped graphs by setting values of Factors at each axis and lining every points, and lastly 3) Measuring the area of the graph for Quality Characteristic Value. In this paper, this methodology is applied to Plant Control System. In addition, the series of quantification frameworks exhibit some good characteristics in the view of software quality factor. More than any thing else, it is believed that introduced framework may be applicable to regulatory guide, software approval procedures, due to its soundness and simple characteristics. (authors)

  17. Experimental determination of pcav factors for cylindrical ionisation chambers in electron beams

    International Nuclear Information System (INIS)

    Palm, Aa.; Mattsson, O.

    2000-01-01

    The electron beam method recommended for calibrating plane parallel ionisation chambers involves cavity correction factors for cylindrical chambers. The cavity correction factors in the IAEA TRS-381 Code of Practice are based on measurements at R 100 in a PMMA phantom using PMMA cylindrical chambers having different cavity radii. In the present work the recommended data were confirmed for electron beams delivered by modern medical accelerators by using the very same phantom and ionisation chambers that were used in the original work. From another series of measurements, using four specially designed wall-less chambers in a graphite phantom, the linear relation between p cav and the chamber radius that is the basis for the experimental method, was verified. The method was also used to determine the cavity correction factors for a set of Farmer-like graphite chambers placed in water. Compared to the TRS-381 Code of Practice a smaller correction was found for the cavity perturbation for the graphite chambers used in water. (author)

  18. Identifying key hospital service quality factors in online health communities.

    Science.gov (United States)

    Jung, Yuchul; Hur, Cinyoung; Jung, Dain; Kim, Minki

    2015-04-07

    The volume of health-related user-created content, especially hospital-related questions and answers in online health communities, has rapidly increased. Patients and caregivers participate in online community activities to share their experiences, exchange information, and ask about recommended or discredited hospitals. However, there is little research on how to identify hospital service quality automatically from the online communities. In the past, in-depth analysis of hospitals has used random sampling surveys. However, such surveys are becoming impractical owing to the rapidly increasing volume of online data and the diverse analysis requirements of related stakeholders. As a solution for utilizing large-scale health-related information, we propose a novel approach to identify hospital service quality factors and overtime trends automatically from online health communities, especially hospital-related questions and answers. We defined social media-based key quality factors for hospitals. In addition, we developed text mining techniques to detect such factors that frequently occur in online health communities. After detecting these factors that represent qualitative aspects of hospitals, we applied a sentiment analysis to recognize the types of recommendations in messages posted within online health communities. Korea's two biggest online portals were used to test the effectiveness of detection of social media-based key quality factors for hospitals. To evaluate the proposed text mining techniques, we performed manual evaluations on the extraction and classification results, such as hospital name, service quality factors, and recommendation types using a random sample of messages (ie, 5.44% (9450/173,748) of the total messages). Service quality factor detection and hospital name extraction achieved average F1 scores of 91% and 78%, respectively. In terms of recommendation classification, performance (ie, precision) is 78% on average. Extraction and

  19. Long-term stability of beam quality and output of conventional X-ray units.

    Science.gov (United States)

    Fukuda, Atsushi; Matsubara, Kosuke; Miyati, Tosiaki

    2015-01-01

    Conventional diagnostic X-ray units are used for radiographic imaging in many countries. For obtaining entrance surface doses, a numerical dose determination method has been applied in Japan. Although this technique is effective, it has to account for errors, particularly fluctuations, due to the beam quality and output of X-ray tubes. As a part of our quality control procedures, we recorded the entrance surface air kerma, tube voltage, and half-value layer measurements made for four diagnostic X-ray tubes over a 103-week period. The entrance surface air kerma for one of the four X-ray tubes had increased significantly by 11.4 % over 1 year from its initial setting, whereas the tube voltages and half-value layers did not deviate significantly from their initial values. Medical physicists and radiological technologists should be aware of this fluctuation for diagnostic X-ray tubes and take it into consideration when calculating the entrance surface air kerma.

  20. Helium ion microscopy of graphene: beam damage, image quality and edge contrast

    International Nuclear Information System (INIS)

    Fox, D; Zhou, Y B; O’Neill, A; Wang, J J; Coleman, J N; Donegan, J F; Zhang, H Z; Kumar, S; Duesberg, G S

    2013-01-01

    A study to analyse beam damage, image quality and edge contrast in the helium ion microscope (HIM) has been undertaken. The sample investigated was graphene. Raman spectroscopy was used to quantify the disorder that can be introduced into the graphene as a function of helium ion dose. The effects of the dose on both freestanding and supported graphene were compared. These doses were then correlated directly to image quality by imaging graphene flakes at high magnification. It was found that a high magnification image with a good signal to noise ratio will introduce very significant sample damage. A safe imaging dose of the order of 10 13 He + cm −2 was established, with both graphene samples becoming highly defective at doses over 5 × 10 14 He + cm −2 . The edge contrast of a freestanding graphene flake imaged in the HIM was then compared with the contrast of the same flake observed in a scanning electron microscope and a transmission electron microscope. Very strong edge sensitivity was observed in the HIM. This enhanced edge sensitivity over the other techniques investigated makes the HIM a powerful nanoscale dimensional metrology tool, with the capability of both fabricating and imaging features with sub-nanometre resolution. (paper)

  1. Monte Carlo computed machine-specific correction factors for reference dosimetry of TomoTherapy static beam for several ion chambers

    International Nuclear Information System (INIS)

    Sterpin, E.; Mackie, T. R.; Vynckier, S.

    2012-01-01

    Purpose: To determine k Q msr ,Q o f msr ,f o correction factors for machine-specific reference (msr) conditions by Monte Carlo (MC) simulations for reference dosimetry of TomoTherapy static beams for ion chambers Exradin A1SL, A12; PTW 30006, 31010 Semiflex, 31014 PinPoint, 31018 microLion; NE 2571. Methods: For the calibration of TomoTherapy units, reference conditions specified in current codes of practice like IAEA/TRS-398 and AAPM/TG-51 cannot be realized. To cope with this issue, Alfonso et al. [Med. Phys. 35, 5179–5186 (2008)] described a new formalism introducing msr factors k Q msr ,Q o f msr ,f o for reference dosimetry, applicable to static TomoTherapy beams. In this study, those factors were computed directly using MC simulations for Q 0 corresponding to a simplified 60 Co beam in TRS-398 reference conditions (at 10 cm depth). The msr conditions were a 10 × 5 cm 2 TomoTherapy beam, source-surface distance of 85 cm and 10 cm depth. The chambers were modeled according to technical drawings using the egs++ package and the MC simulations were run with the egs c hamber user code. Phase-space files used as the source input were produced using PENELOPE after simulation of a simplified 60 Co beam and the TomoTherapy treatment head modeled according to technical drawings. Correlated sampling, intermediate phase-space storage, and photon cross-section enhancement variance reduction techniques were used. The simulations were stopped when the combined standard uncertainty was below 0.2%. Results: Computed k Q msr ,Q o f msr ,f o values were all close to one, in a range from 0.991 for the PinPoint chamber to 1.000 for the Exradin A12 with a statistical uncertainty below 0.2%. Considering a beam quality Q defined as the TPR 20,10 for a 6 MV Elekta photon beam (0.661), the additional correction k Q msr, Q f msr, f ref to k Q,Q o defined in Alfonso et al. [Med. Phys. 35, 5179–5186 (2008)] formalism was in a range from 0.997 to 1.004.Conclusion: The MC computed

  2. A feasibility study of the Dynamic Phantom scanner for quality assurance of beam profiles at various gantry angles

    Science.gov (United States)

    Zhang, Yunkai; Hsi, Wen C.; Chu, James C.H.; Bernard, Damian B.; Abrams, Ross A.

    2005-01-01

    The effect of gantry rotation on beam profiles of photon and electron beams is an important issue in quality assurance for radiotherapy. To address variations in the profiles of photon and electron beams at different gantry angles, a Dynamic Phantom scanner composed of a 20×12×6 cm3 scanning Lucite block was designed as a cross‐beam‐profile scanner. To our knowledge, differences between scanned profiles acquired at different gantry angles with a small size Lucite block and those acquired a full‐size (60×60×50 cm3) water phantom have not been previously investigated. We therefore performed a feasibility study for a first prototype Dynamic Phantom scanner without a gantry attachment mount. Radiation beams from a Varian LINAC 21EX and 2100C were used. Photon beams (6 MV and 18 MV) were shaped by either collimator jaws or a Varian 120 Multileaf (MLC) collimator, and electron beams (6 MeV, 12 MeV, and 20 MeV) were shaped by a treatment cone. To investigate the effect on profiles by using a Lucite block, a quantitative comparison of scanned profiles with the Dynamic Phantom and a full‐size water phantom was first performed at a 0° gantry angle for both photon and electron beams. For photon beam profiles defined by jaws at 1.0 cm and 5.0 cm depths of Lucite (i.e., at 1.1 cm and 5.7 cm depth of water), a good agreement (less than 1% variation) inside the field edge was observed between profiles scanned with the Dynamic Phantom and with a water phantom. The use of Lucite in the Dynamic Phantom resulted in reduced penumbra width (about 0.5 mm out of 5 mm to 8 mm) and reduced (1% to 2%) scatter dose beyond the field edges for both 6 MV and 18 MV beams, compared with the water phantom scanner. For profiles of the MLC‐shaped 6 MV photon beam, a similar agreement was observed. For profiles of electron beams scanned at 2.9 cm depth of Lucite (i.e., at 3.3 cm depth of water), larger disagreements in profiles (3% to 4%) and penumbra width (3 mm to 4 mm out of 12 mm

  3. Factors affecting quality of life in cancer patients undergoing ...

    African Journals Online (AJOL)

    Factors affecting quality of life in cancer patients undergoing chemotherapy. ... Objective: The aim of this study was to evaluate the QoL in cancer patients with solid tumors and at the different chemotherapy cycles (CT). ... Results: A significant relationship between the cancer type, pain intensity, and fatigue was found.

  4. DEPENDENCE RELATIONSHIP BETWEEN THE CRITICAL QUALITY FACTORS AND SOCIAL IMPACT

    Directory of Open Access Journals (Sweden)

    José Álvarez García

    2014-10-01

    Full Text Available This paper shows the results of the empirical study conducted in 186 tourist accommodation businesses in Spain certified under the “Q for Tourist Quality”, own System Quality Management. It was raised with the purpose of analyzing the structure of the relationship between critical quality factors and results-social impact, how they operate and the level of their influence on obtaining these results within the company. Starting from a deep theoretical revision we propose a theoretical model together with the hypotheses to be tested, and we proceed to validation using the technique of Structural Equation Models. The results obtained show that companies wishing to improve their social impact should take into account that leadership is the most important factor to achieve it. Leadership indirectly affects the social impact through its influence on alliances and resources, quality policy/planning, personnel management and learning.

  5. Monolithic integration of collimating Fresnel lens for beam quality enhancement in tapered high-power laser diode

    NARCIS (Netherlands)

    Lau, F.K.; Tee, C.W.; Zhao, Xin; Williams, K.A.; Penty, R.V.; White, I.H.; Calligaro, M.; Lecomte, M.; Parillaud, O.; Michel, N.; Krakowski, M.

    2006-01-01

    We demonstrate, for the first time, a monolithic integrated lens for wide aperture gain-guided tapered laser beam quality enhancement by compensating the quadratic phase curvature. The 3mm long tapered laser with an output aperture of 170µm adopted in this design consists of a gain-guided tapered

  6. Transmission of laser pulses with high output beam quality using step-index fibers having large cladding

    Science.gov (United States)

    Yalin, Azer P; Joshi, Sachin

    2014-06-03

    An apparatus and method for transmission of laser pulses with high output beam quality using large core step-index silica optical fibers having thick cladding, are described. The thick cladding suppresses diffusion of modal power to higher order modes at the core-cladding interface, thereby enabling higher beam quality, M.sup.2, than are observed for large core, thin cladding optical fibers. For a given NA and core size, the thicker the cladding, the better the output beam quality. Mode coupling coefficients, D, has been found to scale approximately as the inverse square of the cladding dimension and the inverse square root of the wavelength. Output from a 2 m long silica optical fiber having a 100 .mu.m core and a 660 .mu.m cladding was found to be close to single mode, with an M.sup.2=1.6. Another thick cladding fiber (400 .mu.m core and 720 .mu.m clad) was used to transmit 1064 nm pulses of nanosecond duration with high beam quality to form gas sparks at the focused output (focused intensity of >100 GW/cm.sup.2), wherein the energy in the core was laser pulses was about 6 ns. Extending the pulse duration provided the ability to increase the delivered pulse energy (>20 mJ delivered for 50 ns pulses) without damaging the silica fiber.

  7. A resonant magnetic field microsensor with high quality factor at atmospheric pressure

    International Nuclear Information System (INIS)

    Herrera-May, A L; García-Ramírez, P J; Martínez-Castillo, J; Sauceda-Carvajal, A; García-González, L; Aguilera-Cortés, L A; Figueras-Costa, E

    2009-01-01

    A resonant magnetic field microsensor with a high quality factor at atmospheric pressure has been designed, fabricated and tested. This microsensor does not require vacuum packaging to operate efficiently and presents a compact and simple geometrical configuration of silicon. This geometry permits us to decrease the size of the structure and facilities its fabrication and operation. It is constructed of a seesaw plate (400 × 150 × 15 µm 3 ), two torsional beams (60 × 40 × 15 µm 3 ), four flexural beams (130 × 12 × 15 µm 3 ) and a Wheatstone bridge with four p-type piezoresistors. The resonant device exploits the Lorentz force principle and operates at its first resonant frequency (136.52 kHz). A sinusoidal excitation current of 22.0 mA with a frequency of 136.52 kHz and magnetic fields from 1 to 400 G are considered. The mechanical response of the microsensor is modeled with the finite element method (FEM). The structure of the microsensor registered a maximum von Mises stress of 53.8 MPa between the flexural and the torsional beams. Additionally, a maximum deflection (372.5 nm) is obtained at the extreme end of the plate. The proposed microsensor has the maximum magnetic sensitivity of 40.3 µV G −1 (magnetic fields −1/2 , theoretical resolution of 1.43 mG Hz −1/2 and power consumption less than 10.0 mW

  8. Real-time determination of laser beam quality by modal decomposition.

    Science.gov (United States)

    Schmidt, Oliver A; Schulze, Christian; Flamm, Daniel; Brüning, Robert; Kaiser, Thomas; Schröter, Siegmund; Duparré, Michael

    2011-03-28

    We present a real-time method to determine the beam propagation ratio M2 of laser beams. The all-optical measurement of modal amplitudes yields M2 parameters conform to the ISO standard method. The experimental technique is simple and fast, which allows to investigate laser beams under conditions inaccessible to other methods.

  9. Factors affecting the adoption of quality assurance technologies in healthcare.

    Science.gov (United States)

    Storey, John

    2013-01-01

    In the light of public concern and of strong policy emphasis on quality and safety in the nursing care of patients in hospital settings, this paper aims to focus on the factors affecting the adoption of innovative quality assurance technologies. Two sets of complementary literature were mined for key themes. Next, new empirical insights were sought. Data gathering was conducted in three phases. The first involved contact with NHS Technology Hubs and other institutions which had insights into leading centres in quality assurance technologies. The second phase was a series of telephone interviews with lead nurses in those hospitals which were identified in the first phase as comprising the leading centres. The third phase comprised a series of face to face interviews with innovators and adopters of healthcare quality assurance technologies in five hospital trusts. There were three main sets of findings. First, despite the strong policy push and the templates established at national level, there were significant variations in the nature and robustness of the quality assurance toolkits that were developed, adapted and adopted. Second, in most of the adopting cases there were important obstacles to the full adoption of the toolkits that were designed. Third, the extent and nature of the ambition of the developers varied dramatically - some wished to see their work impacting widely across the health service; others had a number of different reasons for wanting to restrict the impact of their work. The general concerns about front-line care and the various inquiries into care quality failures emphasise the need for improved and consistent care quality assurance methodologies and practice. The technology adoption literature gives only partial insight into the nature of the challenges; this paper offers specific insights into the factors inhibiting the full adoption of quality assurance technologies in ward-based care.

  10. A quality assurance framework for the fully automated and objective evaluation of image quality in cone-beam computed tomography

    International Nuclear Information System (INIS)

    Steiding, Christian; Kolditz, Daniel; Kalender, Willi A.

    2014-01-01

    Purpose: Thousands of cone-beam computed tomography (CBCT) scanners for vascular, maxillofacial, neurological, and body imaging are in clinical use today, but there is no consensus on uniform acceptance and constancy testing for image quality (IQ) and dose yet. The authors developed a quality assurance (QA) framework for fully automated and time-efficient performance evaluation of these systems. In addition, the dependence of objective Fourier-based IQ metrics on direction and position in 3D volumes was investigated for CBCT. Methods: The authors designed a dedicated QA phantom 10 cm in length consisting of five compartments, each with a diameter of 10 cm, and an optional extension ring 16 cm in diameter. A homogeneous section of water-equivalent material allows measuring CT value accuracy, image noise and uniformity, and multidimensional global and local noise power spectra (NPS). For the quantitative determination of 3D high-contrast spatial resolution, the modulation transfer function (MTF) of centrally and peripherally positioned aluminum spheres was computed from edge profiles. Additional in-plane and axial resolution patterns were used to assess resolution qualitatively. The characterization of low-contrast detectability as well as CT value linearity and artifact behavior was tested by utilizing sections with soft-tissue-equivalent and metallic inserts. For an automated QA procedure, a phantom detection algorithm was implemented. All tests used in the dedicated QA program were initially verified in simulation studies and experimentally confirmed on a clinical dental CBCT system. Results: The automated IQ evaluation of volume data sets of the dental CBCT system was achieved with the proposed phantom requiring only one scan for the determination of all desired parameters. Typically, less than 5 min were needed for phantom set-up, scanning, and data analysis. Quantitative evaluation of system performance over time by comparison to previous examinations was also

  11. A quality assurance framework for the fully automated and objective evaluation of image quality in cone-beam computed tomography.

    Science.gov (United States)

    Steiding, Christian; Kolditz, Daniel; Kalender, Willi A

    2014-03-01

    Thousands of cone-beam computed tomography (CBCT) scanners for vascular, maxillofacial, neurological, and body imaging are in clinical use today, but there is no consensus on uniform acceptance and constancy testing for image quality (IQ) and dose yet. The authors developed a quality assurance (QA) framework for fully automated and time-efficient performance evaluation of these systems. In addition, the dependence of objective Fourier-based IQ metrics on direction and position in 3D volumes was investigated for CBCT. The authors designed a dedicated QA phantom 10 cm in length consisting of five compartments, each with a diameter of 10 cm, and an optional extension ring 16 cm in diameter. A homogeneous section of water-equivalent material allows measuring CT value accuracy, image noise and uniformity, and multidimensional global and local noise power spectra (NPS). For the quantitative determination of 3D high-contrast spatial resolution, the modulation transfer function (MTF) of centrally and peripherally positioned aluminum spheres was computed from edge profiles. Additional in-plane and axial resolution patterns were used to assess resolution qualitatively. The characterization of low-contrast detectability as well as CT value linearity and artifact behavior was tested by utilizing sections with soft-tissue-equivalent and metallic inserts. For an automated QA procedure, a phantom detection algorithm was implemented. All tests used in the dedicated QA program were initially verified in simulation studies and experimentally confirmed on a clinical dental CBCT system. The automated IQ evaluation of volume data sets of the dental CBCT system was achieved with the proposed phantom requiring only one scan for the determination of all desired parameters. Typically, less than 5 min were needed for phantom set-up, scanning, and data analysis. Quantitative evaluation of system performance over time by comparison to previous examinations was also verified. The maximum

  12. Development and validation of two phantoms for quality control in cone-beam CT

    International Nuclear Information System (INIS)

    Gomes B, W. O.

    2016-10-01

    The cone beam computed tomography (CBCT) was introduced into the market in the late 90 s and being a relatively new technology, also no well-established quality control protocols. There are currently projects to standardize the use of CBCT. The SEDENTEXCT project was created with the goal of developing guidelines for CBCT, including the development of a phantom for quality control it is proposed. This study aimed at the development and validation of the models of phantom: CQ_IFBA_01 e CQ_IFBA_02, the first filled with water and the second fully with solid structure in PMMA. Both models allow, otherwise the European phantom - SEDENTEXCT, its use in various models of CBCT, independent of the size of the field of view. The two phantoms used to evaluate seven parameters of quality control are: intensity or average value of pixels of five different plastics, signal to noise ratio, resolution, low contrast, spatial resolution, the accuracy of distances on the z axis, the geometric distortion and image uniformity. The spatial resolution is a critical parameter that differs significantly from the other types of scan, and in these two phantom can be evaluated by two different methods: MTF obtained by Fourier transformation of the function LSF (line spread function) and/or by analysis visual image to a pattern of bars up to 16 pl/cm. Validation was performed in three models CBCT: Kodak 9000, i-CAT Classical and Orthophos XG 3-dimensional. All imaging protocols were characterized dosimetric ally with solid state sensors to correlate with the perfect operation. These models were selected by different manufacturers have different characteristics as FOV, maximum voltage, slice thickness and patient positioning mode. The two of phantom models were viable and also showed compliance with the specifications and data available in the literature. We conclude the feasibility of the two phantom models, and model option will be linked to the practicality positioning equipment. (Author)

  13. Regularization design for high-quality cone-beam CT of intracranial hemorrhage using statistical reconstruction

    Science.gov (United States)

    Dang, H.; Stayman, J. W.; Xu, J.; Sisniega, A.; Zbijewski, W.; Wang, X.; Foos, D. H.; Aygun, N.; Koliatsos, V. E.; Siewerdsen, J. H.

    2016-03-01

    Intracranial hemorrhage (ICH) is associated with pathologies such as hemorrhagic stroke and traumatic brain injury. Multi-detector CT is the current front-line imaging modality for detecting ICH (fresh blood contrast 40-80 HU, down to 1 mm). Flat-panel detector (FPD) cone-beam CT (CBCT) offers a potential alternative with a smaller scanner footprint, greater portability, and lower cost potentially well suited to deployment at the point of care outside standard diagnostic radiology and emergency room settings. Previous studies have suggested reliable detection of ICH down to 3 mm in CBCT using high-fidelity artifact correction and penalized weighted least-squared (PWLS) image reconstruction with a post-artifact-correction noise model. However, ICH reconstructed by traditional image regularization exhibits nonuniform spatial resolution and noise due to interaction between the statistical weights and regularization, which potentially degrades the detectability of ICH. In this work, we propose three regularization methods designed to overcome these challenges. The first two compute spatially varying certainty for uniform spatial resolution and noise, respectively. The third computes spatially varying regularization strength to achieve uniform "detectability," combining both spatial resolution and noise in a manner analogous to a delta-function detection task. Experiments were conducted on a CBCT test-bench, and image quality was evaluated for simulated ICH in different regions of an anthropomorphic head. The first two methods improved the uniformity in spatial resolution and noise compared to traditional regularization. The third exhibited the highest uniformity in detectability among all methods and best overall image quality. The proposed regularization provides a valuable means to achieve uniform image quality in CBCT of ICH and is being incorporated in a CBCT prototype for ICH imaging.

  14. Dosimetric commissioning and quality assurance of scanned ion beams at the Italian National Center for Oncological Hadrontherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mirandola, Alfredo, E-mail: mirandola@cnao.it; Molinelli, S.; Vilches Freixas, G.; Mairani, A.; Gallio, E.; Panizza, D.; Russo, S.; Ciocca, M. [Fondazione CNAO, strada Campeggi 53, Pavia 27100 (Italy); Donetti, M. [INFN, Torino 10125, Italy and Fondazione CNAO, strada Campeggi 53, Pavia 27100 (Italy); Magro, G. [INFN–Dipartimento di Fisica, Università degli Studi di Pavia, Via U. Bassi 6, Pavia 27100, Italy and Fondazione CNAO, strada Campeggi 53, Pavia 27100 (Italy); Giordanengo, S. [INFN, Torino 10125 (Italy); Orecchia, R. [Fondazione CNAO, strada Campeggi 53, Pavia 27100, Italy and Radiotherapy Division, European Institute of Oncology, Via Ripamonti 435, Milano 20141 (Italy)

    2015-09-15

    Purpose: To describe the dosimetric commissioning and quality assurance (QA) of the actively scanned proton and carbon ion beams at the Italian National Center for Oncological Hadrontherapy. Methods: The laterally integrated depth-dose-distributions (IDDs) were acquired with the PTW Peakfinder, a variable depth water column, equipped with two Bragg peak ionization chambers. FLUKA Monte Carlo code was used to generate the energy libraries, the IDDs in water, and the fragment spectra for carbon beams. EBT3 films were used for spot size measurements, beam position over the scan field, and homogeneity in 2D-fields. Beam monitor calibration was performed in terms of number of particles per monitor unit using both a Farmer-type and an Advanced Markus ionization chamber. The beam position at the isocenter, beam monitor calibration curve, dose constancy in the center of the spread-out-Bragg-peak, dose homogeneity in 2D-fields, beam energy, spot size, and spot position over the scan field are all checked on a daily basis for both protons and carbon ions and on all beam lines. Results: The simulated IDDs showed an excellent agreement with the measured experimental curves. The measured full width at half maximum (FWHM) of the pencil beam in air at the isocenter was energy-dependent for both particle species: in particular, for protons, the spot size ranged from 0.7 to 2.2 cm. For carbon ions, two sets of spot size are available: FWHM ranged from 0.4 to 0.8 cm (for the smaller spot size) and from 0.8 to 1.1 cm (for the larger one). The spot position was accurate to within ±1 mm over the whole 20 × 20 cm{sup 2} scan field; homogeneity in a uniform squared field was within ±5% for both particle types at any energy. QA results exceeding tolerance levels were rarely found. In the reporting period, the machine downtime was around 6%, of which 4.5% was due to planned maintenance shutdowns. Conclusions: After successful dosimetric beam commissioning, quality assurance measurements

  15. Dosimetric commissioning and quality assurance of scanned ion beams at the Italian National Center for Oncological Hadrontherapy

    International Nuclear Information System (INIS)

    Mirandola, Alfredo; Molinelli, S.; Vilches Freixas, G.; Mairani, A.; Gallio, E.; Panizza, D.; Russo, S.; Ciocca, M.; Donetti, M.; Magro, G.; Giordanengo, S.; Orecchia, R.

    2015-01-01

    Purpose: To describe the dosimetric commissioning and quality assurance (QA) of the actively scanned proton and carbon ion beams at the Italian National Center for Oncological Hadrontherapy. Methods: The laterally integrated depth-dose-distributions (IDDs) were acquired with the PTW Peakfinder, a variable depth water column, equipped with two Bragg peak ionization chambers. FLUKA Monte Carlo code was used to generate the energy libraries, the IDDs in water, and the fragment spectra for carbon beams. EBT3 films were used for spot size measurements, beam position over the scan field, and homogeneity in 2D-fields. Beam monitor calibration was performed in terms of number of particles per monitor unit using both a Farmer-type and an Advanced Markus ionization chamber. The beam position at the isocenter, beam monitor calibration curve, dose constancy in the center of the spread-out-Bragg-peak, dose homogeneity in 2D-fields, beam energy, spot size, and spot position over the scan field are all checked on a daily basis for both protons and carbon ions and on all beam lines. Results: The simulated IDDs showed an excellent agreement with the measured experimental curves. The measured full width at half maximum (FWHM) of the pencil beam in air at the isocenter was energy-dependent for both particle species: in particular, for protons, the spot size ranged from 0.7 to 2.2 cm. For carbon ions, two sets of spot size are available: FWHM ranged from 0.4 to 0.8 cm (for the smaller spot size) and from 0.8 to 1.1 cm (for the larger one). The spot position was accurate to within ±1 mm over the whole 20 × 20 cm"2 scan field; homogeneity in a uniform squared field was within ±5% for both particle types at any energy. QA results exceeding tolerance levels were rarely found. In the reporting period, the machine downtime was around 6%, of which 4.5% was due to planned maintenance shutdowns. Conclusions: After successful dosimetric beam commissioning, quality assurance measurements

  16. Physics and material science of ultra-high quality factor superconducting resonator

    International Nuclear Information System (INIS)

    Vostrikov, Alexander

    2015-01-01

    The nitrogen doping into niobium superconducting radio frequency cavity walls aiming to improve the fundamental mode quality factor is the subject of the research in the given work. Quantitative nitrogen diffusion into niobium model calculating the concentration profile was developed. The model estimations were confirmed with secondary ion mass spectrometry technique measurements. The model made controlled nitrogen doping recipe optimization possible. As a result the robust reproducible recipe for SRF cavity walls treatment with nitrogen doping was developed. The cavities produced with optimized recipe met LCLS-II requirements on quality factor of 2.7 · 10 10 at acceleration field of 16 MV/m. The microscopic effects of nitrogen doping on superconducting niobium properties were studied with low energy muon spin rotation technique and magnetometer measurements. No significant effect of nitrogen on the following features was found: electron mean free path, magnetic field penetration depth, and upper and surface critical magnetic fields. It was detected that for nitrogen doped niobium samples magnetic flux starts to penetrate inside the superconductor at lower external magnetic field value compared to the low temperature baked niobium ones. This explains lower quench field of SRF cavities treated with nitrogen. Quality factor improvement of fundamental mode forced to analyze the high order mode (HOM) impact on the particle beam dynamics. Both resonant and cumulative effects caused by monopole and dipole HOMs respectively are found to be negligible within the requirements for LCLS-II.

  17. Physics and material science of ultra-high quality factor superconducting resonator

    Energy Technology Data Exchange (ETDEWEB)

    Vostrikov, Alexander [Univ. of Chicago, IL (United States)

    2015-08-01

    The nitrogen doping into niobium superconducting radio frequency cavity walls aiming to improve the fundamental mode quality factor is the subject of the research in the given work. Quantitative nitrogen diffusion into niobium model calculating the concentration profile was developed. The model estimations were confirmed with secondary ion mass spectrometry technique measurements. The model made controlled nitrogen doping recipe optimization possible. As a result the robust reproducible recipe for SRF cavity walls treatment with nitrogen doping was developed. The cavities produced with optimized recipe met LCLS–II requirements on quality factor of 2.7 ∙ 1010 at acceleration field of 16 MV/m. The microscopic effects of nitrogen doping on superconducting niobium properties were studied with low energy muon spin rotation technique and magnetometer measurements. No significant effect of nitrogen on the following features was found: electron mean free path, magnetic field penetration depth, and upper and surface critical magnetic fields. It was detected that for nitrogen doped niobium samples magnetic flux starts to penetrate inside the superconductor at lower external magnetic field value compared to the low temperature baked niobium ones. This explains lower quench field of SRF cavities treated with nitrogen. Quality factor improvement of fundamental mode forced to analyze the high order mode (HOM) impact on the particle beam dynamics. Both resonant and cumulative effects caused by monopole and dipole HOMs respectively are found to be negligible within the requirements for LCLS–II.

  18. Conversion of output factor from square field into rectangular field in electron beam

    CERN Document Server

    Wang Jian Hua; Xu Yi Fei

    2002-01-01

    Objective: A simple and accurate calculation method was designed to convert output factor from square field into rectangular field in electron beam, which can be easily implemented in clinical practice. Methods: 6, 12, 15 MeV electron beam, field size 6.0 cm x 7.5 cm, 5.0 cm x 10.0 cm, 6.0 cm x 12.0 cm, TL3000C dosimeter and source-to-surface distance method were used in dose measurement. The measured dose values were compared with the calculated ones from three theoretical equations with the conformation evaluated. Results: The calculated dose values from three theoretical equations differed from the measured ones by 0.23%, 1.30% and 1.10% (6 MeV), 0.63%, 0.90% and 0.73% (12 MeV), 0.50%, 1.80% and 3.40% (15 MeV), conforming best to the equation OUF (X, Y)=[OUF(X,X). OUF(Y,Y)] sup 1 sup / sup 2. When the size of the field was longer than Rp, the difference between the calculated values and measured ones was relatively very small. Conclusions: The output factor in rectangular fields can be accurately calculate...

  19. SU-E-I-59: Image Quality and Dose Measurement for Partial Cone-Beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Abouei, E; Ford, N [University of British Columbia, Vancouver, BC (Canada)

    2014-06-01

    Purpose: To characterize performance of cone beam CT (CBCT) used in dentistry investigating quantitatively the image quality and radiation dose during dental CBCT over different settings for partial rotation of the x-ray tube. Methods: Image quality and dose measurements were done on a variable field of view (FOV) dental CBCT (Carestream 9300). X-ray parameters for clinical settings were adjustable for 2–10 mA, 60–90 kVp, and two optional voxel size values, but time was fixed for each FOV. Image quality was assessed by scanning cylindrical poly-methyl methacrylate (PMMA) image quality phantom (SEDENTEXCT IQ), and then the images were analyzed using ImageJ to calculate image quality parameters such as noise, uniformity, and contrast to noise ratio (CNR). A protocol proposed by SEDENTEXCT, dose index 1 (DI1), was applied to dose measurements obtained using a thimble ionization chamber and cylindrical PMMA dose index phantom (SEDENTEXCT DI). Dose distributions were obtained using Gafchromic film. The phantoms were positioned in the FOV to imitate a clinical positioning. Results: The image noise was 6–12.5% which, when normalized to the difference of mean voxel value of PMMA and air, was comparable between different FOVs. Uniformity was 93.5ß 99.7% across the images. CNR was 1.7–4.2 and 6.3–14.3 for LDPE and Aluminum, respectively. Dose distributions were symmetric about the rotation angle's bisector. For large and medium FOVs at 4 mA and 80–90 kVp, DI1 values were in the range of 1.26–3.23 mGy. DI1 values were between 1.01–1.93 mGy for small FOV (5×5 cm{sup 2}) at 4–5 mA and 75–84 kVp. Conclusion: Noise decreased by increasing kVp, and the CNR increased for each FOV. When FOV size increased, image noise increased and CNR decreased. DI1 values were increased by increasing tube current (mA), tube voltage (kVp), and/or FOV. Funding for this project from NSERC Discovery grant, UBC Faculty of Dentistry Research Equipment Grant and UBC Faculty of

  20. SU-E-I-59: Image Quality and Dose Measurement for Partial Cone-Beam CT

    International Nuclear Information System (INIS)

    Abouei, E; Ford, N

    2014-01-01

    Purpose: To characterize performance of cone beam CT (CBCT) used in dentistry investigating quantitatively the image quality and radiation dose during dental CBCT over different settings for partial rotation of the x-ray tube. Methods: Image quality and dose measurements were done on a variable field of view (FOV) dental CBCT (Carestream 9300). X-ray parameters for clinical settings were adjustable for 2–10 mA, 60–90 kVp, and two optional voxel size values, but time was fixed for each FOV. Image quality was assessed by scanning cylindrical poly-methyl methacrylate (PMMA) image quality phantom (SEDENTEXCT IQ), and then the images were analyzed using ImageJ to calculate image quality parameters such as noise, uniformity, and contrast to noise ratio (CNR). A protocol proposed by SEDENTEXCT, dose index 1 (DI1), was applied to dose measurements obtained using a thimble ionization chamber and cylindrical PMMA dose index phantom (SEDENTEXCT DI). Dose distributions were obtained using Gafchromic film. The phantoms were positioned in the FOV to imitate a clinical positioning. Results: The image noise was 6–12.5% which, when normalized to the difference of mean voxel value of PMMA and air, was comparable between different FOVs. Uniformity was 93.5ß 99.7% across the images. CNR was 1.7–4.2 and 6.3–14.3 for LDPE and Aluminum, respectively. Dose distributions were symmetric about the rotation angle's bisector. For large and medium FOVs at 4 mA and 80–90 kVp, DI1 values were in the range of 1.26–3.23 mGy. DI1 values were between 1.01–1.93 mGy for small FOV (5×5 cm 2 ) at 4–5 mA and 75–84 kVp. Conclusion: Noise decreased by increasing kVp, and the CNR increased for each FOV. When FOV size increased, image noise increased and CNR decreased. DI1 values were increased by increasing tube current (mA), tube voltage (kVp), and/or FOV. Funding for this project from NSERC Discovery grant, UBC Faculty of Dentistry Research Equipment Grant and UBC Faculty of Dentistry

  1. Novel, compact, and simple ND:YVO4 laser with 12 W of CW optical output power and good beam quality

    Science.gov (United States)

    Zimer, H.; Langer, B.; Wittrock, U.; Heine, F.; Hildebrandt, U.; Seel, S.; Lange, R.

    2017-11-01

    We present first, promising experiments with a novel, compact and simple Nd:YVO4 slab laser with 12 W of 1.06 μm optical output power and a beam quality factor M2 2.5. The laser is made of a diffusion-bonded YVO4/Nd:YVO4 composite crystal that exhibits two unique features. First, it ensures a one-dimensional heat removal from the laser crystal, which leads to a temperature profile without detrimental influence on the laser beam. Thus, the induced thermo-optical aberrations to the laser field are low, allowing power scaling with good beam quality. Second, the composite crystal itself acts as a waveguide for the 809 nm pump-light that is supplied from a diode laser bar. Pump-light shaping optics, e.g. fast- or slow-axis collimators can be omitted, reducing the complexity of the system. Pump-light redundancy can be easily achieved. Eventually, the investigated slab laser might be suitable for distortion-free high gain amplification of weak optical signals.

  2. Megavoltage photon beam attenuation by carbon fiber couch tops and its prediction using correction factors

    International Nuclear Information System (INIS)

    Hayashi, Naoki; Shibamoto, Yuta; Obata, Yasunori; Kimura, Takashi; Nakazawa, Hisato; Hagiwara, Masahiro; Hashizume, Chisa I.; Mori, Yoshimasa; Kobayashi, Tatsuya

    2010-01-01

    The purpose of this study was to evaluate the effect of megavoltage photon beam attenuation (PBA) by couch tops and to propose a method for correction of PBA. Four series of phantom measurements were carried out. First, PBA by the exact couch top (ECT, Varian) and Imaging Couch Top (ICT, BrainLAB) was evaluated using a water-equivalent phantom. Second, PBA by Type-S system (Med-Tec), ECT and ICT was compared with a spherical phantom. Third, percentage depth dose (PDD) after passing through ICT was measured to compare with control data of PDD. Forth, the gantry angle dependency of PBA by ICT was evaluated. Then, an equation for PBA correction was elaborated and correction factors for PBA at isocenter were obtained. Finally, this method was applied to a patient with hepatoma. PBA of perpendicular beams by ICT was 4.7% on average. With the increase in field size, the measured values became higher. PBA by ICT was greater than that by Type-S system and ECT. PBA increased significantly as the angle of incidence increased, ranging from 4.3% at 180 deg to 11.2% at 120 deg. Calculated doses obtained by the equation and correction factors agreed quite well with the measured doses between 120 deg and 180 deg of angles of incidence. Also in the patient, PBA by ICT was corrected quite well by the equation and correction factors. In conclusion, PBA and its gantry angle dependency by ICT were observed. This simple method using the equation and correction factors appeared useful to correct the isocenter dose when the PBA effect cannot be corrected by a treatment planning system. (author)

  3. SU-D-209-02: Percent Depth Dose Curves for Fluoroscopic X-Ray Beam Qualities Incorporating Copper Filtration

    Energy Technology Data Exchange (ETDEWEB)

    Wunderle, K [Cleveland Clinic Foundation, Cleveland, OH (United States); Wayne State University School of Medicine, Detroit, MI (United States); Godley, A; Shen, Z; Dong, F [Cleveland Clinic Foundation, Cleveland, OH (United States); Rakowski, J [Wayne State University School of Medicine, Detroit, MI (United States)

    2016-06-15

    Purpose: The purpose of this investigation was to quantify percent depth dose (PDD) curves for fluoroscopic x-ray beam qualities incorporating added copper filtration. Methods: A PTW (Freiburg, Germany) MP3 water tank was used with a Standard Imaging (Middleton, WI) Exradin Model 11 Spokas Chamber to measure PDD curves for 60, 80, 100 and 120 kVp x-ray beams with copper filtration ranging from 0.0–0.9 mm at 22cm and 42cm fields of view from 0 to 150 mm of water. A free-in-air monitor chamber was used to normalize the water tank data to fluctuations in output from the fluoroscope. The measurements were acquired on a Siemens (Erlangen, Germany) Artis ZeeGo fluoroscope. The fluoroscope was inverted from the typical orientation providing an x-ray beam originating from above the water tank. The water tank was positioned so that the water level was located at 60cm from the focal spot; which also represents the focal spot to interventional reference plane distance for that fluoroscope. Results: PDDs for 60, 80, 100, and 120 kVp with 0 mm of copper filtration compared well to previously published data by Fetterly et al. [Med Phys, 28, 205 (2001)] for those beam qualities given differences in fluoroscopes, geometric orientation, type of ionization chamber, and the water tank used for data collection. PDDs for 60, 80, 100, and 120 kVp with copper filtration were obtained and are presented, which have not been previously investigated and published. Conclusion: The equipment and processes used to acquire the reported data were sound and compared well with previously published data for PDDs without copper filtration. PDD data for the fluoroscopic x-ray beams incorporating copper filtration can be used as reference data for estimating organ or soft tissue dose at depth involving similar beam qualities or for comparison with mathematical models.

  4. Experimental investigation of the effect of the laser beam polarization state on the quality of steel sheet cutting

    Science.gov (United States)

    Golyshev, A. A.; Orishich, A. M.; Shulyatyev, V. B.

    2017-10-01

    The paper presents the results of experimental investigation of the effect of the beam polarization on the quality of the oxygen-assisted laser cutting of steel by a CO2-laser. Under consideration is the effect of the laser cutting parameters by the beam with the linear polarization on the cut surface roughness. It is founded that the minimal roughness is reached when the electric field vector is perpendicular to the cutting speed vector. It is concluded that the absorbed power distribution imposes the essential influence on the surface quality, and that the radiation heating of side walls is important to have lower roughness. Obtained results enabled to present probable reasons of the worse surface quality of the metals cut by a fiber laser than the ones cut by a CO2-laser.

  5. Minimal requirements for quality controls in radiotherapy with external beams; Controlli di qualita' essenziali in radioterapia con fasci esterni

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    Physical dosimetric guidelines have been developed by the Italian National Institute of Health study group on quality assurance in radiotherapy to define protocols for quality controls in external beam radiotherapy. While the document does not determine strict rules or firm recommendations, it suggests minimal requirements for quality controls necessary to guarantee an adequate degree of accuracy in external beam radiotherapy. [Italian] Il gruppo di studio Assicurazione di qualita' in radioterapia dell'Istituto Superiore di Sanita' presenta le linee guida per la stesura dei protocolli di controllo di qualita' essenziali necessari a garantire un adeguato livello di accuratezza del trattamento radiante e rappresenta pertanto una parte essenziale del contributo fisico-dosimetrico globale di assicurazione di qualita' in radioterapia con fasci esterni.

  6. Factors associated with poor sleep quality in women with cancer

    Directory of Open Access Journals (Sweden)

    Thalyta Cristina Mansano-Schlosser

    Full Text Available ABSTRACT Objectives: to analyze the factors associated with poor sleep quality, its characteristics and components in women with breast cancer prior to surgery for removing the tumor and throughout the follow-up. Method: longitudinal study in a teaching hospital, with a sample of 102 women. The following were used: a questionnaire for sociodemographic and clinical characterization, the Pittsburgh Sleep Quality Index; the Beck Depression Inventory; and the Herth Hope Scale. Data collection covered from prior to the surgery for removal of the tumor (T0 to T1, on average 3.2 months; T2, on average 6.1 months; and T3, on average 12.4 months. Descriptive statistics and the Generalized Estimating Equations model were used. Results: depression and pain contributed to the increase in the score of the Pittsburgh Sleep Quality Index, and hope, to the reduction of the score - independently - throughout follow-up. Sleep disturbances were the component with the highest score throughout follow-up. Conclusion: the presence of depression and pain, prior to the surgery, contributed to the increase in the global score of the Pittsburgh Sleep Quality Index, which indicates worse quality of sleep throughout follow-up; greater hope, in its turn, influenced the reduction of the score of the Pittsburgh Sleep Quality Index.

  7. Image quality assessment of three limited field-of-view cone-beam computed tomography devices in endodontics

    International Nuclear Information System (INIS)

    Tran, Michel

    2015-01-01

    Since the beginning of Cone Beam Computed Tomography (CBCT) in dento-maxillo-facial radiology, many CBCT devices with different technical aspects and characteristics were produced. Technical variations between CBCT and acquisition settings could involve image quality differences. In order to compare the performance of three limited field-of-view CBCT devices, an objective and subjective evaluation of image quality was carried out using an ex-vivo phantom, which combines both diagnostic and technical features. A significant difference in image quality was found between the five acquisition protocols of the study. (author) [fr

  8. SU-F-T-67: Correction Factors for Monitor Unit Verification of Clinical Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Haywood, J [Mercy Health Partners, Muskegon, MI (United States)

    2016-06-15

    Purpose: Monitor units calculated by electron Monte Carlo treatment planning systems are often higher than TG-71 hand calculations for a majority of patients. Here I’ve calculated tables of geometry and heterogeneity correction factors for correcting electron hand calculations. Method: A flat water phantom with spherical volumes having radii ranging from 3 to 15 cm was created. The spheres were centered with respect to the flat water phantom, and all shapes shared a surface at 100 cm SSD. D{sub max} dose at 100 cm SSD was calculated for each cone and energy on the flat phantom and for the spherical volumes in the absence of the flat phantom. The ratio of dose in the sphere to dose in the flat phantom defined the geometrical correction factor. The heterogeneity factors were then calculated from the unrestricted collisional stopping power for tissues encountered in electron beam treatments. These factors were then used in patient second check calculations. Patient curvature was estimated by the largest sphere that aligns to the patient contour, and appropriate tissue density was read from the physical properties provided by the CT. The resulting MU were compared to those calculated by the treatment planning system and TG-71 hand calculations. Results: The geometry and heterogeneity correction factors range from ∼(0.8–1.0) and ∼(0.9–1.01) respectively for the energies and cones presented. Percent differences for TG-71 hand calculations drop from ∼(3–14)% to ∼(0–2)%. Conclusion: Monitor units calculated with the correction factors typically decrease the percent difference to under actionable levels, < 5%. While these correction factors work for a majority of patients, there are some patient anatomies that do not fit the assumptions made. Using these factors in hand calculations is a first step in bringing the verification monitor units into agreement with the treatment planning system MU.

  9. High-quality electron beam generation and bright betatron radiation from a cascaded laser wakefield accelerator (Conference Presentation)

    Science.gov (United States)

    Liu, Jiansheng; Wang, Wentao; Li, Wentao; Qi, Rong; Zhang, Zhijun; Yu, Changhai; Wang, Cheng; Liu, Jiaqi; Qing, Zhiyong; Ming, Fang; Xu, Yi; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2017-05-01

    One of the major goals of developing laser wakefiled accelerators (LWFAs) is to produce compact high-energy electron beam (e-beam) sources, which are expected to be applied in developing compact x-ray free-electron lasers and monoenergetic gamma-ray sources. Although LWFAs have been demonstrated to generate multi-GeV e-beams, to date they are still failed to produce high quality e beams with several essential properties (narrow energy spread, small transverse emittance and high beam charge) achieved simultaneously. Here we report on the demonstration of a high-quality cascaded LWFA experimentally via manipulating electron injection, seeding in different periods of the wakefield, as well as controlling energy chirp for the compression of energy spread. The cascaded LWFA was powered by a 1-Hz 200-TW femtosecond laser facility at SIOM. High-brightness e beams with peak energies in the range of 200-600 MeV, 0.4-1.2% rms energy spread, 10-80 pC charge, and 0.2 mrad rms divergence are experimentally obtained. Unprecedentedly high 6-dimensional (6-D) brightness B6D,n in units of A/m2/0.1% was estimated at the level of 1015-16, which is very close to the typical brightness of e beams from state-of-the-art linac drivers and several-fold higher than those of previously reported LWFAs. Furthermore, we propose a scheme to minimize the energy spread of an e beam in a cascaded LWFA to the one-thousandth-level by inserting a stage to compress its longitudinal spatial distribution via velocity bunching. In this scheme, three-segment plasma stages are designed for electron injection, e-beam length compression, and e-beam acceleration, respectively. A one-dimensional theory and two-dimensional particle-in-cell simulations have demonstrated this scheme and an e beam with 0.2% rms energy spread and low transverse emittance could be generated without loss of charge. Based on the high-quality e beams generated in the LWFA, we have experimentally realized a new scheme to enhance the

  10. The study of surgical image quality evaluation system by subjective quality factor method

    Science.gov (United States)

    Zhang, Jian J.; Xuan, Jason R.; Yang, Xirong; Yu, Honggang; Koullick, Edouard

    2016-03-01

    GreenLightTM procedure is an effective and economical way of treatment of benign prostate hyperplasia (BPH); there are almost a million of patients treated with GreenLightTM worldwide. During the surgical procedure, the surgeon or physician will rely on the monitoring video system to survey and confirm the surgical progress. There are a few obstructions that could greatly affect the image quality of the monitoring video, like laser glare by the tissue and body fluid, air bubbles and debris generated by tissue evaporation, and bleeding, just to name a few. In order to improve the physician's visual experience of a laser surgical procedure, the system performance parameter related to image quality needs to be well defined. However, since image quality is the integrated set of perceptions of the overall degree of excellence of an image, or in other words, image quality is the perceptually weighted combination of significant attributes (contrast, graininess …) of an image when considered in its marketplace or application, there is no standard definition on overall image or video quality especially for the no-reference case (without a standard chart as reference). In this study, Subjective Quality Factor (SQF) and acutance are used for no-reference image quality evaluation. Basic image quality parameters, like sharpness, color accuracy, size of obstruction and transmission of obstruction, are used as subparameter to define the rating scale for image quality evaluation or comparison. Sample image groups were evaluated by human observers according to the rating scale. Surveys of physician groups were also conducted with lab generated sample videos. The study shows that human subjective perception is a trustworthy way of image quality evaluation. More systematic investigation on the relationship between video quality and image quality of each frame will be conducted as a future study.

  11. Influence factors of visual quality after phacoemulsification for cataract

    Directory of Open Access Journals (Sweden)

    Zhen-Lin Lin

    2017-12-01

    Full Text Available Cataract refers to the degenerative changes in lens quality caused by various causes of reduced transparency or color change. Surgical treatment is the main treatment modality at present. Among them, phacoemulsification has become the main surgical treatment for cataract because of its advantages such as short operation time, small incision and quicker healing. Today, cataract surgery has gradually shift to refractive surgery, and is no longer simply as cataract surgery. But after cataract phacoemulsification, the symptoms and visual quality are different. The main causes include refractive error, postoperative dry eyes and postoperative corneal astigmatism. This article reviews the factors that influence the visual quality of cataract phacoemulsification and its future trends.

  12. SPS Injection and Beam Quality for LHC Heavy Ions With 150 ns Kicker Rise Time

    CERN Document Server

    Goddard, Brennan; Ducimetière, Laurent; Kotzian, Gerd; Uythoven, Jan; Velotti, Francesco

    2016-01-01

    As part of the LHC Injectors Upgrade project for LHC heavy ions, the SPS injection kicker system rise time needs reduction below its present 225 ns. One technically challenging option under consideration is the addition of fast Pulse Forming Lines in parallel to the existing Pulse Forming Networks for the 12 kicker magnets MKP-S, targeting a system field rise time of 100 ns. An alternative option is to optimise the system to approach the existing individual magnet field rise time (2-98%) of 150 ns. This would still significantly increase the number of colliding bunches in LHC while minimising the cost and effort of the system upgrade. The observed characteristics of the present system are described, compared to the expected system rise time, together with results of simulations and measurements with 175 and 150 ns injection batch spacing. The expected beam quality at injection into LHC is quantified, with the emittance growth and simulated tail population taking into account expected jitter and synchronisatio...

  13. Metering instrument of quality factor Q of gravitational wave antenna

    International Nuclear Information System (INIS)

    Jia-yan, C.; Tong-ren, G.

    1982-01-01

    The quality factor, Q, of gravitational wave antenna depends on the material property as well as external conditions, such as temperature, residual pressure in vacuum tank, support type, additional loss from transducer on antenna, etc. In order to find out the relationship between the antenna Q and external conditions automatical operating in succession is required. The authors have designed and made a metering instrument for quality factor Q. The metering instrument of Q can measure Q of the metal cylinder and other bar of higher Q. It can give data of the measurement at regular intervals as desired. It can measure accurately the longitudinal fundamental mode frequency of the cylinder with a digital frequency meter record oscillating signal from metering instrument. Because the metering instrument excites free-vibration of the cylinder with free-running type and keep up the stationary amplitude for a long time. (Auth.)

  14. Impact of Constant Rate Factor on Objective Video Quality Assessment

    Directory of Open Access Journals (Sweden)

    Juraj Bienik

    2017-01-01

    Full Text Available This paper deals with the impact of constant rate factor value on the objective video quality assessment using PSNR and SSIM metrics. Compression efficiency of H.264 and H.265 codecs defined by different Constant rate factor (CRF values was tested. The assessment was done for eight types of video sequences depending on content for High Definition (HD, Full HD (FHD and Ultra HD (UHD resolution. Finally, performance of both mentioned codecs with emphasis on compression ratio and efficiency of coding was compared.

  15. Nuclear fuel management via fuel quality factor averaging

    International Nuclear Information System (INIS)

    Mingle, J.O.

    1978-01-01

    The numerical procedure of prime number averaging is applied to the fuel quality factor distribution of once and twice-burned fuel in order to evolve a fuel management scheme. The resulting fuel shuffling arrangement produces a near optimal flat power profile both under beginning-of-life and end-of-life conditions. The procedure is easily applied requiring only the solution of linear algebraic equations. (author)

  16. Improving the Optical Quality Factor of the WGM Resonator

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Iltchenko, Vladimir

    2008-01-01

    Resonators usually are characterized with two partially dependent values: finesse (F) and quality factor (Q). The finesse of an empty Fabry-Perot (FP) resonator is defined solely by the quality of its mirrors and is calculated as F=piR(exp 1/2)/(1-R). The maximum up-to-date value of reflectivity R approximately equal to 1 - 1.6 x 10(exp -6) is achieved with dielectric mirrors. An FP resonator made with the mirrors has finesse F=1.9 x 10(exp 6). Further practical increase of the finesse of FP resonators is problematic because of the absorption and the scattering of light in the mirror material through fundamental limit on the reflection losses given by the internal material losses and by thermodynamic density fluctuations on the order of parts in 109. The quality factor of a resonator depends on both its finesse and its geometrical size. A one-dimensional FP resonator has Q=2 F L/lambda, where L is the distance between the mirrors and lambda is the wavelength. It is easy to see that the quality factor of the resonator is unlimited because L is unlimited. F and Q are equally important. In some cases, finesse is technically more valuable than the quality factor. For instance, buildup of the optical power inside the resonator, as well as the Purcell factor, is proportional to finesse. Sometimes, however, the quality factor is more valuable. For example, inverse threshold power of intracavity hyperparametric oscillation is proportional to Q(exp 2) and efficiency of parametric frequency mixing is proportional to Q(exp 3). Therefore, it is important to know both the maximally achievable finesse and quality factor values of a resonator. Whispering gallery mode (WGM) resonators are capable of achieving larger finesse compared to FP resonators. For instance, fused silica resonators with finesse 2.3 x 10(exp 6) and 2.8 x 10(exp 6) have been demonstrated. Crystalline WGM resonators reveal even larger finesse values, F=6.3 x 10(exp 6), because of low attenuation of light in the

  17. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    International Nuclear Information System (INIS)

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J.; Kuncic, Zdenka

    2014-01-01

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  18. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    Energy Technology Data Exchange (ETDEWEB)

    Shieh, Chun-Chien [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006, Australia and Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J., E-mail: paul.keall@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006 (Australia); Kuncic, Zdenka [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia)

    2014-04-15

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  19. High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Musumeci, P.; Moody, J. T.; Scoby, C. M.; Gutierrez, M. S. [Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States); Bender, H. A.; Wilcox, N. S. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

    2010-01-15

    Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

  20. High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector.

    Science.gov (United States)

    Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Bender, H A; Wilcox, N S

    2010-01-01

    Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

  1. High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector

    International Nuclear Information System (INIS)

    Musumeci, P.; Moody, J. T.; Scoby, C. M.; Gutierrez, M. S.; Bender, H. A.; Wilcox, N. S.

    2010-01-01

    Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

  2. Radioactive beam production at the Bevalac

    International Nuclear Information System (INIS)

    Alonso, J.R.; Feinberg, B.; Kalnins, J.G.; Krebs, G.F.; McMahan, M.A.; Tanihata, I.

    1989-10-01

    At the Bevalac radioactive beams are routinely produced by the fragmentation process. The effectiveness of this process with respect to the secondary beam's emittance, intensity and energy spread depends critically on the nuclear reaction kinematics and the magnitude of the incident beam energy. When this beam energy significantly exceeds the energies of the nuclear reaction process, many of the qualities of the incident beam can be passed on to the secondary beam. Factors affecting secondary beam quality are discussed along with techniques for isolating and purifying a specific reaction product. The on-going radioactive beam program at the Bevalac is used as an example with applications, present performance and plans for the future. 6 refs., 6 figs., 1 tab

  3. High-quality laser-accelerated ion beams for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Harman, Zoltan; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); American University of Sharjah (United Arab Emirates)

    2009-07-01

    Cancer radiation therapy requires accelerated ion beams of high energy sharpness and a narrow spatial profile. As shown recently, linearly and radially polarized, tightly focused and thus extremely strong laser beams should permit the direct acceleration of light atomic nuclei up to energies that may offer the potentiality for medical applications. Radially polarized beams have better emittance than their linearly polarized counterparts. We put forward the direct laser acceleration of ions, once the refocusing of ion beams by external fields is solved or radially polarized laser pulses of sufficient power can be generated.

  4. Production of high-quality electron bunches by dephasing and beam loading in channeled and unchanneled laser plasma accelerators

    International Nuclear Information System (INIS)

    Geddes, C.G.R.; Toth, Cs.; Tilborg, J. van; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

    2005-01-01

    High-quality electron beams, with a few 10 9 electrons within a few percent of the same energy above 80 MeV, were produced in a laser wakefield accelerator by matching the acceleration length to the length over which electrons were accelerated and outran (dephased from) the wake. A plasma channel guided the drive laser over long distances, resulting in production of the high-energy, high-quality beams. Unchanneled experiments varying the length of the target plasma indicated that the high-quality bunches are produced near the dephasing length and demonstrated that channel guiding was more stable and efficient than relativistic self-guiding. Consistent with these data, particle-in-cell simulations indicate production of high-quality electron beams when trapping of an initial bunch of electrons suppresses further injection by loading the wake. The injected electron bunch is then compressed in energy by dephasing, when the front of the bunch begins to decelerate while the tail is still accelerated

  5. SU-E-T-571: Newly Emerging Integrated Transmission Detector Systems Provide Online Quality Assurance of External Beam Radiation Therapy

    International Nuclear Information System (INIS)

    Hoffman, D; Chung, E; Hess, C; Stern, R; Benedict, S

    2015-01-01

    Purpose: Two newly emerging transmission detectors positioned upstream from the patient have been evaluated for online quality assurance of external beam radiotherapy. The prototype for the Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area ion chamber mounted on the linac accessory tray to monitor photon fluence, energy, beam shape, and gantry position during treatment. The ion chamber utilizes a thickness gradient which records variable response dependent on beam position. The prototype of Delta4 Discover™, developed by ScandiDos (Uppsala, Sweden) is a linac accessory tray mounted 4040 diode array that measures photon fluence during patient treatment. Both systems are employable for patient specific QA prior to treatment delivery. Methods: Our institution evaluated the reproducibility of measurements using various beam types, including VMAT treatment plans with both the IQM ion chamber and the Delta4 Discover diode array. Additionally, the IQM’s effect on photon fluence, dose response, simulated beam error detection, and the accuracy of the integrated barometer, thermometer, and inclinometer were characterized. The evaluated photon beam errors are based on the annual tolerances specified in AAPM TG-142. Results: Repeated VMAT treatments were measured with 0.16% reproducibility by the IQM and 0.55% reproducibility by the Delta4 Discover. The IQM attenuated 6, 10, and 15 MV photon beams by 5.43±0.02%, 4.60±0.02%, and 4.21±0.03% respectively. Photon beam profiles were affected <1.5% in the non-penumbra regions. The IQM’s ion chamber’s dose response was linear and the thermometer, barometer, and inclinometer agreed with other calibrated devices. The device detected variations in monitor units delivered (1%), field position (3mm), single MLC leaf positions (13mm), and photon energy. Conclusion: We have characterized two new transmissions detector systems designed to provide in-vivo like measurements upstream

  6. SU-E-T-571: Newly Emerging Integrated Transmission Detector Systems Provide Online Quality Assurance of External Beam Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D; Chung, E; Hess, C; Stern, R; Benedict, S [UC Davis Cancer Center, Sacramento, CA (United States)

    2015-06-15

    Purpose: Two newly emerging transmission detectors positioned upstream from the patient have been evaluated for online quality assurance of external beam radiotherapy. The prototype for the Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area ion chamber mounted on the linac accessory tray to monitor photon fluence, energy, beam shape, and gantry position during treatment. The ion chamber utilizes a thickness gradient which records variable response dependent on beam position. The prototype of Delta4 Discover™, developed by ScandiDos (Uppsala, Sweden) is a linac accessory tray mounted 4040 diode array that measures photon fluence during patient treatment. Both systems are employable for patient specific QA prior to treatment delivery. Methods: Our institution evaluated the reproducibility of measurements using various beam types, including VMAT treatment plans with both the IQM ion chamber and the Delta4 Discover diode array. Additionally, the IQM’s effect on photon fluence, dose response, simulated beam error detection, and the accuracy of the integrated barometer, thermometer, and inclinometer were characterized. The evaluated photon beam errors are based on the annual tolerances specified in AAPM TG-142. Results: Repeated VMAT treatments were measured with 0.16% reproducibility by the IQM and 0.55% reproducibility by the Delta4 Discover. The IQM attenuated 6, 10, and 15 MV photon beams by 5.43±0.02%, 4.60±0.02%, and 4.21±0.03% respectively. Photon beam profiles were affected <1.5% in the non-penumbra regions. The IQM’s ion chamber’s dose response was linear and the thermometer, barometer, and inclinometer agreed with other calibrated devices. The device detected variations in monitor units delivered (1%), field position (3mm), single MLC leaf positions (13mm), and photon energy. Conclusion: We have characterized two new transmissions detector systems designed to provide in-vivo like measurements upstream

  7. Antiscatter grids in mobile C-arm cone-beam CT: Effect on image quality and dose

    Energy Technology Data Exchange (ETDEWEB)

    Schafer, S.; Stayman, J.W.; Zbijewski, W.; Schmidgunst, C.; Kleinszig, G.; Siewerdsen, J.H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Siemens Healthcare XP Division, Erlangen, Bavaria 91052 (Germany); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States) and Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2012-01-15

    Purpose: X-ray scatter is a major detriment to image quality in cone-beam CT (CBCT). Existing geometries exhibit strong differences in scatter susceptibility with more compact geometries, e.g., dental or musculoskeletal, benefiting from antiscatter grids, whereas in more extended geometries, e.g., IGRT, grid use carries tradeoffs in image quality per unit dose. This work assesses the tradeoffs in dose and image quality for grids applied in the context of low-dose CBCT on a mobile C-arm for image-guided surgery. Methods: Studies were performed on a mobile C-arm equipped with a flat-panel detector for high-quality CBCT. Antiscatter grids of grid ratio (GR) 6:1-12:1, 40 lp/cm, were tested in ''body'' surgery, i.e., spine, using protocols for bone and soft-tissue visibility in the thoracic and abdominal spine. Studies focused on grid orientation, CT number accuracy, image noise, and contrast-to-noise ratio (CNR) in quantitative phantoms at constant dose. Results: There was no effect of grid orientation on possible gridline artifacts, given accurate angle-dependent gain calibration. Incorrect calibration was found to result in gridline shadows in the projection data that imparted high-frequency artifacts in 3D reconstructions. Increasing GR reduced errors in CT number from 31%, thorax, and 37%, abdomen, for gridless operation to 2% and 10%, respectively, with a 12:1 grid, while image noise increased by up to 70%. The CNR of high-contrast objects was largely unaffected by grids, but low-contrast soft-tissues suffered reduction in CNR, 2%-65%, across the investigated GR at constant dose. Conclusions: While grids improved CT number accuracy, soft-tissue CNR was reduced due to attenuation of primary radiation. CNR could be restored by increasing dose by factors of {approx}1.6-2.5 depending on GR, e.g., increase from 4.6 mGy for the thorax and 12.5 mGy for the abdomen without antiscatter grids to approximately 12 mGy and 30 mGy, respectively, with a high

  8. Development and validation of two phantoms for quality control in cone-beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Gomes B, W. O., E-mail: wilsonottobatista@gmail.com [Instituto Federal da Bahia, Rua Emidio dos Santos s/n, Barbalho 40301-015, Salvador de Bahia (Brazil)

    2016-10-15

    The cone beam computed tomography (CBCT) was introduced into the market in the late 90 s and being a relatively new technology, also no well-established quality control protocols. There are currently projects to standardize the use of CBCT. The SEDENTEXCT project was created with the goal of developing guidelines for CBCT, including the development of a phantom for quality control it is proposed. This study aimed at the development and validation of the models of phantom: CQ{sub I}FBA{sub 0}1 e CQ{sub I}FBA{sub 0}2, the first filled with water and the second fully with solid structure in PMMA. Both models allow, otherwise the European phantom - SEDENTEXCT, its use in various models of CBCT, independent of the size of the field of view. The two phantoms used to evaluate seven parameters of quality control are: intensity or average value of pixels of five different plastics, signal to noise ratio, resolution, low contrast, spatial resolution, the accuracy of distances on the z axis, the geometric distortion and image uniformity. The spatial resolution is a critical parameter that differs significantly from the other types of scan, and in these two phantom can be evaluated by two different methods: MTF obtained by Fourier transformation of the function LSF (line spread function) and/or by analysis visual image to a pattern of bars up to 16 pl/cm. Validation was performed in three models CBCT: Kodak 9000, i-CAT Classical and Orthophos XG 3-dimensional. All imaging protocols were characterized dosimetric ally with solid state sensors to correlate with the perfect operation. These models were selected by different manufacturers have different characteristics as FOV, maximum voltage, slice thickness and patient positioning mode. The two of phantom models were viable and also showed compliance with the specifications and data available in the literature. We conclude the feasibility of the two phantom models, and model option will be linked to the practicality positioning

  9. Determination Of Output Factor For Photon Beam Of The Mitsubishi EXL-14 Linear Accelerator

    International Nuclear Information System (INIS)

    Nurman R; Sri-Inang S; Dani

    2003-01-01

    This paper describes the determination of output factor for 6 MV photon beam of The Mitsubishi EXL-14 linear accelerator teletherapy unit. Determination of percentage depth dose curve has been done using Wallhofer dosemeter at source to surface distance, SSD of 100 cm and field size of 10 cm x 10 cm. Measurement of output has been carried out using a 0.6 cc ionization chamber inside a water phantom at depth of 5 cm with source to surface distance, SSD of 100 cm for square fields ranging in size 4 cm x 4 cm up to 10 cm x 10 cm. Output for rectangular fields which equal to the equivalent square fields were also determined. The results obtained shows that the deviations of the output for 12 cm x 3 cm and 19 cm x 7 cm were higher than ±2% to the output of the equivalent square fields. (author)

  10. Quality control in the development of coagulation factor concentrates.

    Science.gov (United States)

    Snape, T J

    1987-01-01

    Limitation of process change is a major factor contributing to assurance of quality in pharmaceutical manufacturing. This is particularly true in the manufacture of coagulation factor concentrates, for which presumptive testing for poorly defined product characteristics is an integral feature of finished product quality control. The development of new or modified preparations requires that this comfortable position be abandoned, and that the effect on finished product characteristics of changes to individual process steps (and components) be assessed. The degree of confidence in the safety and efficacy of the new product will be determined by, amongst other things, the complexity of the process alteration and the extent to which the results of finished product tests can be considered predictive. The introduction of a heat-treatment step for inactivation of potential viral contaminants in coagulation factor concentrates presents a significant challenge in both respects, quite independent of any consideration of assessment of the effectiveness of the viral inactivation step. These interactions are illustrated by some of the problems encountered with terminal dry heat-treatment (72 h. at 80 degrees C) of factor VIII and prothrombin complex concentrates manufactured by the Blood Products Laboratory.

  11. Quality management in the nuclear industry: the human factor

    International Nuclear Information System (INIS)

    1990-01-01

    In the nuclear industry it is vital to understand the 'human factor' with regard to plant performance and plant safety. A proper management system ensures that personnel perform their duties correctly. 'Quality Management in the Nuclear Industry: the Human Factor', was a conference organized by the Institution of Mechanical Engineers in October 1990. The conference covered a wide range of topics on an international level including: standards, licensing and regulatory procedures; selection assessment and training of personnel; feedback from experience of good practice and of deviations; management and support of personnel performance; modelling and evaluation of human factors. The papers presented at the conference are contained in this volume. All twenty papers are indexed separately. (author)

  12. The geographical factor in the determination of audit quality

    Directory of Open Access Journals (Sweden)

    Antonio Luis Duréndez Gómez-Guillamón

    2012-12-01

    Full Text Available The aim of this research paper is to analyze the role of the spatial factor in the determination of audit quality. Concretely, we hypothesize that audit quality is influenced by location and by the existence of spill-over effects generated by two factors: (1 the specialization and reputation of auditing firms and (2 the economic and institutional development of the audit firm’s location. We developed an empirical research to test the existence of such spatial effects (location and spill-over on a representative sample of the Spanish audit market. The study includes spatial econometric techniques taking into account the auditee specific characteristics, as well as other external factors. The findings highlight the relevance of including the spatial dimension when the audit quality is being studied. The results confirm the existence of a location effect according to the highest quality values are found in the most developed Spanish areas. Furthermore, we find a spatial spill-over effect among regions, affecting audit quality values. This effect confirms that audit quality within a location spreads to its surroundings. The results support the promotion of governmental policies leading to improve audit quality considering the spill-over effect.KEYWORDS: RESUMENEl objetivo de este artículo es analizar la influencia del factor geográfico en la determinación de la calidad de la auditoría. En concreto, la hipótesis que se plantea sostiene que la calidad de la auditoría se ve afectada por la ubicación y por la existencia de efectos indirectos generados por dos factores: (1 la especialización y la reputación de las firmas de auditoría y (2 el desarrollo económico e institucional de la provincia donde se localiza la firma de auditoría. Con este objetivo hemos desarrollado un estudio empírico para probar la existencia de tales efectos espaciales (ubicación y desbordamiento en una muestra representativa del mercado de auditoría español. El

  13. The quest for μ → eγ and its experimental limiting factors at future high intensity muon beams

    Energy Technology Data Exchange (ETDEWEB)

    Cavoto, G. [' ' Sapienza' ' Univ., Roma (Italy). Dipt. di Fisica; Istituto Nazionale di Fisica Nucleare, Rome (Italy); Papa, A. [Paul Scherrer Institut, Villigen (Switzerland); Renga, F.; Voena, C. [Istituto Nazionale di Fisica Nucleare, Rome (Italy); Ripiccini, E. [Geneve Univ. (Switzerland). Dept. de Physique Nucleaire et Corpusculaire

    2018-01-15

    The search for the lepton flavor violating decay μ{sup +} → e{sup +}γ will reach an unprecedented level of sensitivity within the next five years thanks to the MEG-II experiment. This experiment will take data at the Paul Scherrer Institut where continuous muon beams are delivered at a rate of about 10{sup 8} muons per second. On the same time scale, accelerator upgrades are expected in various facilities, making it feasible to have continuous beams with an intensity of 10{sup 9} or even 10{sup 10} muons per second. We investigate the experimental limiting factors that will define the ultimate performances, and hence the sensitivity, in the search for μ{sup +} → e{sup +}γ with a continuous beam at these extremely high rates. We then consider some conceptual detector designs and evaluate the corresponding sensitivity as a function of the beam intensity. (orig.)

  14. Measurement of g factors of excited states in radioactive beams by the transient field technique: 132Te

    International Nuclear Information System (INIS)

    Benczer-Koller, N.; Kumbartzki, G.; Gurdal, G; Gross, Carl J; Krieger, B; Hatarik, Robert; O'Malley, Patrick; Pain, S. D.; Segen, L.; Baktash, Cyrus; Bingham, C. R.; Danchev, M.; Grzywacz, R.; Mazzocchi, C.

    2008-01-01

    The g factor of the 2 1 + state in 52 132 Te, E(2 1 + ) = 0.9739 MeV, r = 2.6 ps, was measured by the transient field technique applied to a radioactive beam. The development of an experimental approach necessary for work in radioactive beam environments is described. The result g = 0.28(15) agrees with the previous measurement by the recoil-in-vacuum technique, but here the sign of the g factor is measured as well

  15. Can We Predict Plan Quality for External Beam Partial Breast Irradiation: Results of a Multicenter Feasibility Study (Trans Tasman Radiation Oncology Group Study 06.02)

    Energy Technology Data Exchange (ETDEWEB)

    Kron, Tomas, E-mail: Tomas.Kron@petermac.org [Peter MacCallum Cancer Centre, Departments of Radiation Oncology, Physical Sciences and Radiation Therapy, Melbourne, Victoria (Australia); Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria (Australia); School of Science, Engineering and Technology, Royal Melbourne Institute of Technology University, Melbourne, Victoria (Australia); Willis, David; Link, Emma [Peter MacCallum Cancer Centre, Departments of Radiation Oncology, Physical Sciences and Radiation Therapy, Melbourne, Victoria (Australia); Lehman, Margot [Princess Alexandra Hospital, Department of Radiation Oncology, Brisbane, Queensland (Australia); Campbell, Gillian [Auckland City Hospital, Department of Radiation Oncology, Auckland (New Zealand); O' Brien, Peter [Newcastle Calvary Mater Hospital, Department of Radiation Oncology, Newcastle, NSW (Australia); Chua, Boon [Peter MacCallum Cancer Centre, Departments of Radiation Oncology, Physical Sciences and Radiation Therapy, Melbourne, Victoria (Australia); Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria (Australia)

    2013-11-15

    Purpose: Partial breast irradiation (PBI) after lumpectomy may be an option for selected patients with early breast cancer. A feasibility study of accelerated PBI delivered using external beam 3-dimensional conformal radiation therapy (RT) was undertaken at 8 Australasian centers. The present study evaluated the impact of patient, tumor, and RT technique-related factors on the quality of RT plans as determined by the dose–volume parameters of organs at risk. Methods and Materials: Forty-eight patients were enrolled in the study. All RT plans were centrally reviewed using predefined dosimetric criteria before commencement and after completion of protocol therapy. The RT plans of 47 patients met the dose–volume constraints, and all 47 patients received PBI to a prescribed dose of 38.5 Gy in 10 fractions. The RT plan quality was determined by volumes of the ipsilateral whole breast, lung, and heart that received 50% and 95%; 30%; and 5% of the prescribed dose, respectively. Patient, tumor, and RT technique-related factors were investigated for association with the parameters of RT plan quality. Results: The ratio of the planning target volume to the ipsilateral whole-breast volume was significantly associated with the ipsilateral breast doses on multiple variable analyses. The distance of the postlumpectomy surgical cavity from the heart and lung were predictive for heart and lung doses, respectively. A distance between surgical cavity and heart of >4 cm typically resulted in <1% of the heart volume receiving 5 Gy or less. It was more difficult to meet the heart dose constraint for left-sided and medially located tumors. Conclusions: Partial breast irradiation using 3-dimensional conformal RT was feasible within the study constraints. The ratio of planning target volume to ipsilateral whole-breast volume and the distance of surgical cavity from the heart were significant predictors of the quality of treatment plan for external beam PBI.

  16. Can We Predict Plan Quality for External Beam Partial Breast Irradiation: Results of a Multicenter Feasibility Study (Trans Tasman Radiation Oncology Group Study 06.02)

    International Nuclear Information System (INIS)

    Kron, Tomas; Willis, David; Link, Emma; Lehman, Margot; Campbell, Gillian; O'Brien, Peter; Chua, Boon

    2013-01-01

    Purpose: Partial breast irradiation (PBI) after lumpectomy may be an option for selected patients with early breast cancer. A feasibility study of accelerated PBI delivered using external beam 3-dimensional conformal radiation therapy (RT) was undertaken at 8 Australasian centers. The present study evaluated the impact of patient, tumor, and RT technique-related factors on the quality of RT plans as determined by the dose–volume parameters of organs at risk. Methods and Materials: Forty-eight patients were enrolled in the study. All RT plans were centrally reviewed using predefined dosimetric criteria before commencement and after completion of protocol therapy. The RT plans of 47 patients met the dose–volume constraints, and all 47 patients received PBI to a prescribed dose of 38.5 Gy in 10 fractions. The RT plan quality was determined by volumes of the ipsilateral whole breast, lung, and heart that received 50% and 95%; 30%; and 5% of the prescribed dose, respectively. Patient, tumor, and RT technique-related factors were investigated for association with the parameters of RT plan quality. Results: The ratio of the planning target volume to the ipsilateral whole-breast volume was significantly associated with the ipsilateral breast doses on multiple variable analyses. The distance of the postlumpectomy surgical cavity from the heart and lung were predictive for heart and lung doses, respectively. A distance between surgical cavity and heart of >4 cm typically resulted in <1% of the heart volume receiving 5 Gy or less. It was more difficult to meet the heart dose constraint for left-sided and medially located tumors. Conclusions: Partial breast irradiation using 3-dimensional conformal RT was feasible within the study constraints. The ratio of planning target volume to ipsilateral whole-breast volume and the distance of surgical cavity from the heart were significant predictors of the quality of treatment plan for external beam PBI

  17. Optimization of laser parameters to obtain high-energy, high-quality electron beams through laser-plasma acceleration

    International Nuclear Information System (INIS)

    Samant, Sushil Arun; Sarkar, Deepangkar; Krishnagopal, Srinivas; Upadhyay, Ajay K.; Jha, Pallavi

    2010-01-01

    The propagation of an intense (a 0 =3), short-pulse (L∼λ p ) laser through a homogeneous plasma has been investigated. Using two-dimensional simulations for a 0 =3, the pulse-length and spot-size at three different plasma densities were optimized in order to get a better quality beam in laser wakefield accelerator. The study reveals that with increasing pulse-length the acceleration increases, but after a certain pulse-length (L>0.23λ p ) the emittance blows-up unacceptably. For spot-sizes less than that given by k p0 r s =2√(a 0 ), trapping is poor or nonexistent, and the optimal spot-size is larger. The deviation of the optimal spot-size from this formula increases as the density decreases. The efficacy of these two-dimensional simulations has been validated by running three-dimensional simulations at the highest density. It has been shown that good quality GeV-class beams can be obtained at plasma densities of ∼10 18 cm -3 . The quality of the beam can be substantially improved by selecting only the high-energy peak; in this fashion an energy-spread of better than 1% and a current in tens of kA can be achieved, which are important for applications such as free-electron lasers.

  18. Factors influencing groundwater quality: towards an integrated management approach.

    Science.gov (United States)

    De Giglio, O; Quaranta, A; Barbuti, G; Napoli, C; Caggiano, G; Montagna, M T

    2015-01-01

    The safety of groundwater resources is a serious issue, particularly when these resources are the main source of water for drinking, irrigation and industrial use in coastal areas. In Italy, 85% of the water used by the public is of underground origin. The aim of this report is to analyze the main factors that make groundwater vulnerable. Soil characteristics and filtration capacity can promote or hinder the diffusion of environmental contaminants. Global climate change influences the prevalence and degree of groundwater contamination. Anthropic pressure causes considerable exploitation of water resources, leading to reduced water availability and the progressive deterioration of water quality. Management of water quality will require a multidisciplinary, dynamic and practical approach focused on identifying the measures necessary to reduce contamination and mitigate the risks associated with the use of contaminated water resources.

  19. The development of an interdepartmental audit as part of a physics quality assurance programme for external beam therapy

    International Nuclear Information System (INIS)

    Bonnett, D.E.; Jaukett, R.J.; Mills, J.A.; Martin-Smith, P.

    1994-01-01

    A cost-effective audit system has been developed that will both detect systematic error in data and procedures, and evaluate the quality assurance programme provided by a physics department for radiotherapy. The audit has been developed for external beam radiotherapy and assesses one modality and one treatment machine per year. The method of assessing the quality assurance programme and the schedule of measurements are described. The process is illustrated using the results of trial audits between the medical physics department at Coventry and Leicester. (author)

  20. Natural and anthropogenic factors affecting the groundwater quality in Serbia.

    Science.gov (United States)

    Devic, Gordana; Djordjevic, Dragana; Sakan, Sanja

    2014-01-15

    Various chemometric techniques were used to analyze the quality of groundwater data sets. Seventeen water quality parameters: the cations Na, K, Ca, Mg, the anions Cl, SO4, NO3, HCO3 and nine trace elements Pb, As, Mn, Ni, Cu, Cd, Fe, Zn and Cr were measured at 66 different key sampling sites in ten representative areas (low land-Northern Autonomous Province of Serbia, Vojvodina and central Serbia) for the summer period of 2009. HCA grouped the sample sites into four clusters based on the similarities of the characteristics of the groundwater quality. DA showed two parameters, HCO3 and Zn, affording more than 90% correct assignments in the spatial analysis of four/three different regions in Serbia. Factor analysis was applied on the log-transformed data sets and allowed the identification of a reduced number of factors with hydrochemical meaning. The results showed severe pollution with Mn, As, NO3, Ni, Pb whereby anthropogenic origin of these contaminants was indicated. The pollution comes from both scattered point sources (industrial and urban effluent) and diffuse source agricultural activity. These samples may not be suitable for human consumption; the water quality belongs to class III/IV (contaminated). The Fe anomalies (7.1mg/L) in the water from the Vetrnica site can be attributed to natural sources, such as the dissolution of rock masses and rock fragments. The serious groundwater contamination with As (25.7-137.8 μg/L) in the area of Banat (Northern Autonomous Province of Serbia, Vojvodina) and a sample No. 9 at the Great Morava River requires urgent attention. © 2013.

  1. Factors Associated with the Quality of Transient Elastography.

    Science.gov (United States)

    Juárez-Hernández, Eva; Uribe-Ramos, Martha Helena; Ramos-Ostos, Martha Helena; López-Ramírez, Angélica Yanine; Ornelas-Arroyo, Sofía; Romero-Flores, Juan Luis; Méndez-Sánchez, Nahúm; Uribe, Misael; Chávez-Tapia, Norberto C

    2015-07-01

    Transient elastography is a noninvasive method for the evaluation of fibrosis in chronic liver disease. However, its reliability is variable, and the factors associated with its accuracy have not been identified completely. To identify the factors associated with the reliability of transient elastography. A total of 2033 transient elastography measurements were taken from March 2009 to October 2013. Reliability was determined according to the interquartile range/median (IQR/M reliable; IQR/M reliable). Other indicators such as the percentage of successful measurements (>60 %), time of performance, and probe size were recorded. Potential factors that could affect the reliability of the procedure were analyzed using multivariate logistic regression. Slightly less than 5 % of the measurements were unsuccessful, and 83 % of the successful measurements were found to be reliable. Factors associated with an unsuccessful measurement were female gender, incorrect probe size, and the presence of HCV infection. Unreliable measurements were associated with use of the procedure as part of a clinical study and success rate. Very reliable evaluations were associated with >10 measurements, the presence of chronic hepatic disease, and a success rate of >60 %. The operator and clinical and anthropometric characteristics are factors that influence the success and reliability of transient elastography. Improvements in the quality of the procedure are needed to provide better diagnostic accuracy in clinical practice.

  2. Health related quality of life and influencing factors among welders.

    Directory of Open Access Journals (Sweden)

    Jingxiang Qin

    Full Text Available BACKGROUND: Occupational exposure to welding fumes is a serious occupational health problem all over the world. Welders are exposed to many occupational hazards; these hazards might cause some occupational diseases. The aim of the study was to assess the health related quality of life (HRQL of electric welders in Shanghai China and explore influencing factors to HRQL of welders. METHODS: 301 male welders (without pneumoconiosis and 305 non-dust male workers in Shanghai were enrolled in this study. Short Form-36 (SF-36 health survey questionnaires were applied in this cross-sectional study. Socio-demographic, working and health factors were also collected. Multiple stepwise regress analysis was used to identify significant factors related to the eight dimension scores. RESULTS: Six dimensions including role-physical (RP, bodily pain (BP, general health (GH, validity (VT, social function (SF, and mental health (MH were significantly worse in welders compared to non-dust workers. Multiple stepwise regress analysis results show that native place, monthly income, quantity of children, drinking, sleep time, welding type, use of personal protective equipment (PPE, great events in life, and some symptoms including dizziness, discomfort of cervical vertebra, low back pain, cough and insomnia may be influencing factors for HRQL of welders. Among these factors, only sleep time and the use of PPE were salutary. CONCLUSIONS: Some dimensions of HRQL of these welders have been affected. Enterprises which employ welders should take measures to protect the health of these people and improve their HRQL.

  3. Survey-assessed quality and organizational factors related to quality in Pursuing Perfection hospitals.

    Science.gov (United States)

    Shwartz, Michael; Cramer, Irene E; Holmes, Sally K; Cohen, Alan B; Restuccia, Joseph D; VanDeusen Lukas, Carol; Sullivan, Jennifer L; Charns, Martin P

    2010-01-01

    The goal of the Pursuing Perfection (P2) program was to encourage organizations to push quality improvement to new levels of excellence. As part of an evaluation of P2, we surveyed employees at the 7 participating P2 organizations to (1) assess their perceptions of patient care quality and improvement progress and (2) examine perceived performance on organizational and workgroup characteristics associated with quality. Many survey questions were drawn from existing conceptual models and survey instruments. We used factor analysis to create new scales from questions that were not part of established scales. We used correlation coefficients and multivariable models to examine relationships among variables. Variables most strongly associated with perceived quality included standardized and simplified care processes resulting in coordinated care and smooth handoffs, a clear sense of organizational direction and clear action plans, and communication with staff about reasons for change and improvement progress made. Of those variables with a strong relationship to quality, ones with relatively low mean ratings included workgroup coordination; sufficient resources and support for improvement; training; and efficient use of people, time, and energy. These are important areas on which management should focus to improve employee ratings of quality.

  4. Effect of electron beam irradiation on the quality of mackerel (Pneumatophorus japonicus) Meat

    International Nuclear Information System (INIS)

    Wu Dongxiao; Yang Wenge; Xu Dalun; Zhou Xingyu; Ou Changrong; Shi Huidong

    2012-01-01

    The effect of 3, 5, 7 kGy electron beam irradiation on the volatile basic nitrogen (VBN) and peroxide value (POV), the contents of histamine and unsaturated fatty acid (UFA) in Pneumatophorus japonicus meat with vacuum or ordinary package were measured during refrigeration. The results showed that electron beam treatment could effectively control the contents of histamine and VBN, postpone the oxidation of unsaturated fatty acid in P. japonicus meat. The shelf life of P. japonicus meat could be extended with electron beam irradiation. Before cold storage, it is appropriate that the P. japonicus meat were ordinary packaged and irradiated at the dose of 5 kGy. (authors)

  5. Determination of absorbed dose calibration factors for therapy level electron beam ionization chambers.

    Science.gov (United States)

    McEwen, M R; Williams, A J; DuSautoy, A R

    2001-03-01

    Over several years the National Physical Laboratory (NPL) has been developing an absorbed dose calibration service for electron beam radiotherapy. To test this service, a number of trial calibrations of therapy level electron beam ionization chambers have been carried out during the last 3 years. These trials involved 17 UK radiotherapy centres supplying a total of 46 chambers of the NACP, Markus, Roos and Farmer types. Calibration factors were derived from the primary standard calorimeter at seven energies in the range 4 to 19 MeV with an estimated uncertainty of +/-1.5% at the 95% confidence level. Investigations were also carried out into chamber perturbation, polarity effects, ion recombination and repeatability of the calibration process. The instruments were returned to the radiotherapy centres for measurements to be carried out comparing the NPL direct calibration with the 1996 IPEMB air kerma based Code of Practice. It was found that, in general, all chambers of a particular type showed the same energy response. However, it was found that polarity and recombination corrections were quite variable for Markus chambers-differences in the polarity correction of up to 1% were seen. Perturbation corrections were obtained and were found to agree well with the standard data used in the IPEMB Code. The results of the comparison between the NPL calibration and IPEMB Code show agreement between the two methods at the +/-1% level for the NACP and Farmer chambers, but there is a significant difference for the Markus chambers of around 2%. This difference between chamber types is most likely to be due to the design of the Markus chamber.

  6. Quality factor of a transmission line coupled coplanar waveguide resonator

    Energy Technology Data Exchange (ETDEWEB)

    Besedin, Ilya [National University for Science and Technology (MISiS), Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Menushenkov, Alexey P. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2018-12-15

    We investigate analytically the coupling of a coplanar waveguide resonator to a coplanar waveguide feedline. Using a conformal mapping technique we obtain an expression for the characteristic mode impedances and coupling coefficients of an asymmetric multi-conductor transmission line. Leading order terms for the external quality factor and frequency shift are calculated. The obtained analytical results are relevant for designing circuit-QED quantum systems and frequency division multiplexing of superconducting bolometers, detectors and similar microwave-range multi-pixel devices. (orig.)

  7. Detailed characterization of electron sources yielding first demonstration of European X-ray Free-Electron Laser beam quality

    Directory of Open Access Journals (Sweden)

    F. Stephan

    2010-02-01

    Full Text Available The photoinjector test facility at DESY, Zeuthen site (PITZ, was built to develop and optimize photoelectron sources for superconducting linacs for high-brilliance, short-wavelength free-electron laser (FEL applications like the free-electron laser in Hamburg (FLASH and the European x-ray free-electron laser (XFEL. In this paper, the detailed characterization of two laser-driven rf guns with different operating conditions is described. One experimental optimization of the beam parameters was performed at an accelerating gradient of about 43  MV/m at the photocathode and the other at about 60  MV/m. In both cases, electron beams with very high phase-space density have been demonstrated at a bunch charge of 1 nC and are compared with corresponding simulations. The rf gun optimized for the lower gradient has surpassed all the FLASH requirements on beam quality and rf parameters (gradient, rf pulse length, repetition rate and serves as a spare gun for this facility. The rf gun studied with increased accelerating gradient at the cathode produced beams with even higher brightness, yielding the first demonstration of the beam quality required for driving the European XFEL: The geometric mean of the normalized projected rms emittance in the two transverse directions was measured to be 1.26±0.13  mm mrad for a 1-nC electron bunch. When a 10% charge cut is applied excluding electrons from those phase-space regions where the measured phase-space density is below a certain level and which are not expected to contribute to the lasing process, the normalized projected rms emittance is about 0.9 mm mrad.

  8. Ion-recombination correction factor κsat for spherical ion chambers irradiated by continuous photom beams

    International Nuclear Information System (INIS)

    Piermattei, A.; Azario, L.; Arcovito, G.

    1996-01-01

    The large range of reference air kerma rates of brachytherapy sources involves the use of large-volume ionization chambers. When such ionization chambers are used the ion-recombination correction factor k sat has to be determined. In this paper three spherical ion chambers with volume ranging from 30 to 10 4 cm 3 have been irradiated by photons of a 192 Ir source to determine the k sat factors. The ionization currents of the ion chambers as a function of the applied voltage and the air kerma rate have been analysed to determine the contribution of the initial and general ion recombination. The k sat values for large-volume ionization chambers obtained by considering the general ion recombination as predominant (Almond's approach) are in disagreement with the results obtained using methods that consider both initial and general ion-recombination contributions (Niatel's approach). Such disagreement can reach 0.7% when high currents are measured for a high-activity source calibration in terms of reference air kerma rate. In this study a new 'two-voltage' method, independent of the voltage ratio given by a dosimetry system, is proposed for practical dosimetry of continuous x-and gamma-radiation beams. In the case where the Almond approach is utilized, the voltage ratio V 1 /V 2 should be less than 2 instead of Almond's limit of V 1 /V 2 <5. (Author)

  9. Hydrophone area-averaging correction factors in nonlinearly generated ultrasonic beams

    International Nuclear Information System (INIS)

    Cooling, M P; Humphrey, V F; Wilkens, V

    2011-01-01

    The nonlinear propagation of an ultrasonic wave can be used to produce a wavefield rich in higher frequency components that is ideally suited to the calibration, or inter-calibration, of hydrophones. These techniques usually use a tone-burst signal, limiting the measurements to harmonics of the fundamental calibration frequency. Alternatively, using a short pulse enables calibration at a continuous spectrum of frequencies. Such a technique is used at PTB in conjunction with an optical measurement technique to calibrate devices. Experimental findings indicate that the area-averaging correction factor for a hydrophone in such a field demonstrates a complex behaviour, most notably varying periodically between frequencies that are harmonics of the centre frequency of the original pulse and frequencies that lie midway between these harmonics. The beam characteristics of such nonlinearly generated fields have been investigated using a finite difference solution to the nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation for a focused field. The simulation results are used to calculate the hydrophone area-averaging correction factors for 0.2 mm and 0.5 mm devices. The results clearly demonstrate a number of significant features observed in the experimental investigations, including the variation with frequency, drive level and hydrophone element size. An explanation for these effects is also proposed.

  10. Hydrophone area-averaging correction factors in nonlinearly generated ultrasonic beams

    Science.gov (United States)

    Cooling, M. P.; Humphrey, V. F.; Wilkens, V.

    2011-02-01

    The nonlinear propagation of an ultrasonic wave can be used to produce a wavefield rich in higher frequency components that is ideally suited to the calibration, or inter-calibration, of hydrophones. These techniques usually use a tone-burst signal, limiting the measurements to harmonics of the fundamental calibration frequency. Alternatively, using a short pulse enables calibration at a continuous spectrum of frequencies. Such a technique is used at PTB in conjunction with an optical measurement technique to calibrate devices. Experimental findings indicate that the area-averaging correction factor for a hydrophone in such a field demonstrates a complex behaviour, most notably varying periodically between frequencies that are harmonics of the centre frequency of the original pulse and frequencies that lie midway between these harmonics. The beam characteristics of such nonlinearly generated fields have been investigated using a finite difference solution to the nonlinear Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation for a focused field. The simulation results are used to calculate the hydrophone area-averaging correction factors for 0.2 mm and 0.5 mm devices. The results clearly demonstrate a number of significant features observed in the experimental investigations, including the variation with frequency, drive level and hydrophone element size. An explanation for these effects is also proposed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

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

    Science.gov (United States)

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

    2011-12-01

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

  13. Environmental factors contributed to circannual rhythm of semen quality.

    Science.gov (United States)

    Mao, Huan; Feng, Lei; Yang, Wan-Xi

    2017-01-01

    We investigated whether human semen parameters present circannual rhythm or not, and whether environmental factors exert on semen quality. This retrospective study used data of patients mainly from Reproductive Medicine Center and Urology and Andrology Clinic of a general hospital in China. Sperm concentration and motility were measured by computer aided sperm analysis (CASA). Sperm morphology was scored based on the strict criteria (WHO, 2010). The Kruskal-Wallis rank test was used to investigate the relationship between semen parameters and season/month. Partial correlation coefficients were used to analyze the relationship between semen parameters and environmental factors. In this study, we found that sperm concentration and total amount per ejaculate were significantly lower in summer and higher in winter. But, sperm progressive motility and motility were significantly higher in spring and summer (from March to June), lower in autumn and winter (September and October). Unexpectedly, normal sperm morphology and mixed agglutination reaction (MAR) positive rate didn't vary along with season or month. Furthermore, temperature was negatively related to sperm concentration and total amount per ejaculate. Precipitation was positively associated with progressive motility and normal sperm morphology, but negatively related to sperm head defect percentage. The length of sunlight was positively related to progressive motility. The Air Quality Index (AQI) was positively associated with semen volume and sperm total amount per ejaculate. These suggest seasonal and monthly variation underlying some semen parameters.

  14. Ultra Stable, Industrial Green Tailored Pulse Fiber Laser with Diffraction-limited Beam Quality for Advanced Micromachining

    International Nuclear Information System (INIS)

    Deladurantaye, P; Roy, V; Desbiens, L; Drolet, M; Taillon, Y; Galarneau, P

    2011-01-01

    We report on a novel pulsed fiber laser platform providing pulse shaping agility at high repetition rates and at a wavelength of 532 nm. The oscillator is based on the direct modulation of a seed laser diode followed by a chain of fiber amplifiers. Advanced Large Mode Area (LMA) fiber designs as well as proprietary techniques to mitigate non-linear effects enable output energy per pulse up to 100 μJ at 1064 nm with diffraction-limited beam quality and narrow line widths suitable for efficient frequency conversion. Ultra stable pulses with tailored pulse shapes were demonstrated in the green region of the spectrum at repetition rates higher than 200 kHz. Pulse durations between 2.5 ns and 640 ns are available, as well as pulse to pulse dynamic shape selection at repetition rates up to 1 MHz. The pulse energy stability at 532 nm is better than ± 1.5%, 3σ, over 10 000 pulses. Excellent beam characteristics were obtained. The M 2 parameter is lower than 1.05, the beam waist astigmatism and beam waist asymmetry are below 10% and below 8% respectively, with high stability over time. We foresee that the small spot size, high repetition rate and pulse tailoring capability of this platform will provide advantages to practitioners who are developing novel, advanced processes in many industrially important applications.

  15. Effects of electron beam irradiation on chemical composition, antinutritional factors, ruminal degradation and in vitro protein digestibility of canola meal

    Science.gov (United States)

    Taghinejad-Roudbaneh, M.; Ebrahimi, S. R.; Azizi, S.; Shawrang, P.

    2010-12-01

    The aim of the present study was to determine the impact of electron beam (EB) irradiation at doses of 15, 30 and 45 kGy on the nutritional value of canola meal. The phytic acid and total glucosinolate content of EB-irradiated canola meal decreased as irradiation doses increased ( Pruminal degradation and reducing antinutritional factors of irradiated canola meal.

  16. Accelerating an Ordered-Subset Low-Dose X-Ray Cone Beam Computed Tomography Image Reconstruction with a Power Factor and Total Variation Minimization.

    Science.gov (United States)

    Huang, Hsuan-Ming; Hsiao, Ing-Tsung

    2016-01-01

    In recent years, there has been increased interest in low-dose X-ray cone beam computed tomography (CBCT) in many fields, including dentistry, guided radiotherapy and small animal imaging. Despite reducing the radiation dose, low-dose CBCT has not gained widespread acceptance in routine clinical practice. In addition to performing more evaluation studies, developing a fast and high-quality reconstruction algorithm is required. In this work, we propose an iterative reconstruction method that accelerates ordered-subsets (OS) reconstruction using a power factor. Furthermore, we combine it with the total-variation (TV) minimization method. Both simulation and phantom studies were conducted to evaluate the performance of the proposed method. Results show that the proposed method can accelerate conventional OS methods, greatly increase the convergence speed in early iterations. Moreover, applying the TV minimization to the power acceleration scheme can further improve the image quality while preserving the fast convergence rate.

  17. Should image rotation be addressed during routine cone-beam CT quality assurance?

    International Nuclear Information System (INIS)

    Ayan, Ahmet S; Lin Haibo; Yeager, Caitlyn; Deville, Curtiland; McDonough, James; Zhu, Timothy C; Anderson, Nathan; Ad, Voichita Bar; Both, Stefan; Lu, Hsiao-Ming

    2013-01-01

    The purpose of this study is to investigate whether quality assurance (QA) for cone-beam computed tomography (CBCT) image rotation is necessary in order to ensure the accuracy of CBCT based image-guided radiation therapy (IGRT) and adaptive radiotherapy (ART). Misregistration of angular coordinates during CBCT acquisition may lead to a rotated reconstructed image. If target localization is performed based on this image, an under- or over-dosage of the target volume (TV) and organs at risk (OARs) may occur. Therefore, patient CT image sets were rotated by 1° up to 3° and the treatment plans were recalculated to quantify changes in dose–volume histograms. A computer code in C++ was written to model the TV displacement and overlap area of an ellipse shape at the target and dose prescription levels corresponding to the image rotation. We investigated clinical scenarios in IGRT and ART in order to study the implications of image rotation on dose distributions for: (1) lateral TV and isocenter (SBRT), (2) central TV and isocenter (IMRT), (3) lateral TV and isocenter (IMRT). Mathematical analysis showed the dose coverage of TV depends on its shape, size, location, and orientation relative to the isocenter. Evaluation of three first scenario for θ = 1° showed variations in TV D95 in the context of IGRT and ART when compared to the original plan were within 2.7 ± 2.6% and 7.7 ± 6.9% respectively while variations in the second and third scenarios were less significant (<0.5%) for the angular range evaluated. However a larger degree of variation was found in terms of minimum and maximum doses for target and OARs. The rotation of CBCT image data sets may have significant dosimetric consequences in IGRT and ART. The TV's location relative to isocenter and shape determine the extent of alterations in dose indicators. Our findings suggest that a CBCT QA criterion of 1° would be a reasonable action level to ensure accurate dose delivery. (paper)

  18. Should image rotation be addressed during routine cone-beam CT quality assurance?

    Science.gov (United States)

    Ayan, Ahmet S.; Lin, Haibo; Yeager, Caitlyn; Deville, Curtiland; McDonough, James; Zhu, Timothy C.; Anderson, Nathan; Bar Ad, Voichita; Lu, Hsiao-Ming; Both, Stefan

    2013-02-01

    The purpose of this study is to investigate whether quality assurance (QA) for cone-beam computed tomography (CBCT) image rotation is necessary in order to ensure the accuracy of CBCT based image-guided radiation therapy (IGRT) and adaptive radiotherapy (ART). Misregistration of angular coordinates during CBCT acquisition may lead to a rotated reconstructed image. If target localization is performed based on this image, an under- or over-dosage of the target volume (TV) and organs at risk (OARs) may occur. Therefore, patient CT image sets were rotated by 1° up to 3° and the treatment plans were recalculated to quantify changes in dose-volume histograms. A computer code in C++ was written to model the TV displacement and overlap area of an ellipse shape at the target and dose prescription levels corresponding to the image rotation. We investigated clinical scenarios in IGRT and ART in order to study the implications of image rotation on dose distributions for: (1) lateral TV and isocenter (SBRT), (2) central TV and isocenter (IMRT), (3) lateral TV and isocenter (IMRT). Mathematical analysis showed the dose coverage of TV depends on its shape, size, location, and orientation relative to the isocenter. Evaluation of three first scenario for θ = 1° showed variations in TV D95 in the context of IGRT and ART when compared to the original plan were within 2.7 ± 2.6% and 7.7 ± 6.9% respectively while variations in the second and third scenarios were less significant (<0.5%) for the angular range evaluated. However a larger degree of variation was found in terms of minimum and maximum doses for target and OARs. The rotation of CBCT image data sets may have significant dosimetric consequences in IGRT and ART. The TV's location relative to isocenter and shape determine the extent of alterations in dose indicators. Our findings suggest that a CBCT QA criterion of 1° would be a reasonable action level to ensure accurate dose delivery.

  19. Task-based statistical image reconstruction for high-quality cone-beam CT

    Science.gov (United States)

    Dang, Hao; Webster Stayman, J.; Xu, Jennifer; Zbijewski, Wojciech; Sisniega, Alejandro; Mow, Michael; Wang, Xiaohui; Foos, David H.; Aygun, Nafi; Koliatsos, Vassilis E.; Siewerdsen, Jeffrey H.

    2017-11-01

    Task-based analysis of medical imaging performance underlies many ongoing efforts in the development of new imaging systems. In statistical image reconstruction, regularization is often formulated in terms to encourage smoothness and/or sharpness (e.g. a linear, quadratic, or Huber penalty) but without explicit formulation of the task. We propose an alternative regularization approach in which a spatially varying penalty is determined that maximizes task-based imaging performance at every location in a 3D image. We apply the method to model-based image reconstruction (MBIR—viz., penalized weighted least-squares, PWLS) in cone-beam CT (CBCT) of the head, focusing on the task of detecting a small, low-contrast intracranial hemorrhage (ICH), and we test the performance of the algorithm in the context of a recently developed CBCT prototype for point-of-care imaging of brain injury. Theoretical predictions of local spatial resolution and noise are computed via an optimization by which regularization (specifically, the quadratic penalty strength) is allowed to vary throughout the image to maximize local task-based detectability index ({{d}\\prime} ). Simulation studies and test-bench experiments were performed using an anthropomorphic head phantom. Three PWLS implementations were tested: conventional (constant) penalty; a certainty-based penalty derived to enforce constant point-spread function, PSF; and the task-based penalty derived to maximize local detectability at each location. Conventional (constant) regularization exhibited a fairly strong degree of spatial variation in {{d}\\prime} , and the certainty-based method achieved uniform PSF, but each exhibited a reduction in detectability compared to the task-based method, which improved detectability up to ~15%. The improvement was strongest in areas of high attenuation (skull base), where the conventional and certainty-based methods tended to over-smooth the data. The task-driven reconstruction method presents a

  20. Tandem mirror experiment-upgrade neutral beam test stand: a powerful tool for development and quality assurance

    International Nuclear Information System (INIS)

    Hibbs, S.M.; Kane, R.J.; Kerr, R.G.; Poulsen, P.

    1983-01-01

    During construction of the Tandem Mirror Experiment-Upgrade (TMX-U), we assembled a test stand to develop electronics for the neutral beam system. In the first six months of test stand use we operated a few neutral beam injector modules and directed considerable effort toward improving the electronic system. As system development progressed, our focus turned toward improving the injector modules themselves. The test stand has proved to be the largest single contributor to the successful operation of neutral beams on TMX-U, primarily because it provides quality assurance andd development capability in conjunction with the scheduled activities of the main experiment. This support falls into five major categories: (1) electronics development, (2) operator training, (3) injector module testing and characterization, (4) injector module improvements, and (5) physics improvements (through areas affected by injector operation). Normal day-to-day operation of the test stand comes under the third category, testing and characterization, and comprises our final quality assurance activity for newly assembled or repaired modules before they are installed on TMX-U

  1. Tandem Mirror Experiment-Upgrade neutral beam test stand: A powerful tool for development and quality assurance

    International Nuclear Information System (INIS)

    Hibbs, S.M.; Kane, R.J.; Kerr, R.G.; Poulsen, P.

    1983-01-01

    During construction of the Tandem Mirror Experiment-Upgrade (TMX-U), a test stand was assembled to develop electronics for the neutral beam system. In the first six months of test stand use the authors operated a few neutral beam injector modules and directed considerable effort toward improving the electronic system. As system development progressed, the focus turned toward improving the injector modules themselves. The test stand has proved to be the largest single contributor to the successful operation of neutral beams on TMX-U, primarily because it provides quality assurance and development capability in conjunction with the scheduled activities of the main experiment. This support falls into five major categories: (1) electronics development, (2) operator training, (3) injector module testing and characterization, (4) injector module improvements, and (5) physics improvements (through areas affected by injector operation). Normal day-to-day operation of the test stand comes under the third category, testing and characterization, and comprises the final quality assurance activity for newly assembled or repaired modules before they are installed on TMX-U. They have also used the test stand to perform a series of physics experiments, including: reducing gas flow through valve and arc chamber characterization, reducing impurities by titanium gettering, and reducing streaming gas using apertures and collisional gas dynamics

  2. M2 qualify laser beam propagation

    International Nuclear Information System (INIS)

    Abdelhalim, Bencheikh; Mohamed, Bouafia

    2010-01-01

    One of the most important properties of a laser resonator is the highly collimated or spatially coherent nature of the laser output beam. Laser beam diameter and quality factor M 2 are significant parameters in a wide range of laser applications. This is because the spatial beam quality determines how closely the beam can be focused or how well the beam propagates over long distances without significant dispersion. In the present paper we have used three different methods to qualify the spatial structure of a laser beam propagating in free space, the results are obtained and discussed, and we have found that the Wigner distribution function is a powerful tool which allows a global characterization of any kind of beam

  3. Stroboscopic image capture: Reducing the dose per frame by a factor of 30 does not prevent beam-induced specimen movement in paraffin

    International Nuclear Information System (INIS)

    Typke, Dieter; Gilpin, Christopher J.; Downing, Kenneth H.; Glaeser, Robert M.

    2007-01-01

    Beam-induced specimen movement may be the major factor that limits the quality of high-resolution images of organic specimens. One of the possible measures to improve the situation that was proposed by Henderson and Glaeser [Ultramicroscopy 16 (1985) 139-150], which we refer to here as 'stroboscopic image capture', is to divide the normal exposure into many successive frames, thus reducing the amount of electron exposure-and possibly the amount of beam-induced movement-per frame. The frames would then be aligned and summed. We have performed preliminary experiments on stroboscopic imaging using a 200-kV electron microscope that was equipped with a high dynamic range Charge-coupled device (CCD) camera for image recording and a liquid N 2 -cooled cryoholder. Single-layer paraffin crystals on carbon film were used as a test specimen. The ratio F(g)/F(0) of paraffin reflections, calculated from the images, serves as our criterion for the image quality. In the series that were evaluated, no significant improvement of the F image (g)/F image (0) ratio was found, even though the electron exposure per frame was reduced by a factor of 30. A frame-to-frame analysis of image distortions showed that considerable beam-induced movement had still occurred during each frame. In addition, the paraffin crystal lattice was observed to move relative to the supporting carbon film, a fact that cannot be explained as being an electron-optical effect caused by specimen charging. We conclude that a significant further reduction of the dose per frame (than was possible with this CCD detector) will be needed in order to test whether the frame-to-frame changes ultimately become small enough for stroboscopic image capture to show its potential

  4. Biplane interventional pediatric system with cone‐beam CT: dose and image quality characterization for the default protocols

    Science.gov (United States)

    Vañó, Eliseo; Alejo, Luis; Ubeda, Carlos; Gutiérrez‐Larraya, Federico; Garayoa, Julia

    2016-01-01

    The aim of this study was to assess image quality and radiation dose of a biplane angiographic system with cone‐beam CT (CBCT) capability tuned for pediatric cardiac procedures. The results of this study can be used to explore dose reduction techniques. For pulsed fluoroscopy and cine modes, polymethyl methacrylate phantoms of various thicknesses and a Leeds TOR 18‐FG test object were employed. Various fields of view (FOV) were selected. For CBCT, the study employed head and body dose phantoms, Catphan 504, and an anthropomorphic cardiology phantom. The study also compared two 3D rotational angiography protocols. The entrance surface air kerma per frame increases by a factor of 3–12 when comparing cine and fluoroscopy frames. The biggest difference in the signal‐to‐noise ratio between fluoroscopy and cine modes occurs at FOV 32 cm because fluoroscopy is acquired at a 1440×1440 pixel matrix size and in unbinned mode, whereas cine is acquired at 720×720 pixels and in binned mode. The high‐contrast spatial resolution of cine is better than that of fluoroscopy, except for FOV 32 cm, because fluoroscopy mode with 32 cm FOV is unbinned. Acquiring CBCT series with a 16 cm head phantom using the standard dose protocol results in a threefold dose increase compared with the low‐dose protocol. Although the amount of noise present in the images acquired with the low‐dose protocol is much higher than that obtained with the standard mode, the images present better spatial resolution. A 1 mm diameter rod with 250 Hounsfield units can be distinguished in reconstructed images with an 8 mm slice width. Pediatric‐specific protocols provide lower doses while maintaining sufficient image quality. The system offers a novel 3D imaging mode. The acquisition of CBCT images results in increased doses administered to the patients, but also provides further diagnostic information contained in the volumetric images. The assessed CBCT protocols provide images that are noisy

  5. Biplane interventional pediatric system with cone-beam CT: dose and image quality characterization for the default protocols.

    Science.gov (United States)

    Corredoira, Eva; Vañó, Eliseo; Alejo, Luis; Ubeda, Carlos; Gutiérrez-Larraya, Federico; Garayoa, Julia

    2016-07-08

    The aim of this study was to assess image quality and radiation dose of a biplane angiographic system with cone-beam CT (CBCT) capability tuned for pediatric cardiac procedures. The results of this study can be used to explore dose reduction techniques. For pulsed fluoroscopy and cine modes, polymethyl methacrylate phantoms of various thicknesses and a Leeds TOR 18-FG test object were employed. Various fields of view (FOV) were selected. For CBCT, the study employed head and body dose phantoms, Catphan 504, and an anthropomorphic cardiology phantom. The study also compared two 3D rotational angiography protocols. The entrance surface air kerma per frame increases by a factor of 3-12 when comparing cine and fluoroscopy frames. The biggest difference in the signal-to- noise ratio between fluoroscopy and cine modes occurs at FOV 32 cm because fluoroscopy is acquired at a 1440 × 1440 pixel matrix size and in unbinned mode, whereas cine is acquired at 720 × 720 pixels and in binned mode. The high-contrast spatial resolution of cine is better than that of fluoroscopy, except for FOV 32 cm, because fluoroscopy mode with 32 cm FOV is unbinned. Acquiring CBCT series with a 16 cm head phantom using the standard dose protocol results in a threefold dose increase compared with the low-dose protocol. Although the amount of noise present in the images acquired with the low-dose protocol is much higher than that obtained with the standard mode, the images present better spatial resolution. A 1 mm diameter rod with 250 Hounsfield units can be distinguished in reconstructed images with an 8 mm slice width. Pediatric-specific protocols provide lower doses while maintaining sufficient image quality. The system offers a novel 3D imaging mode. The acquisition of CBCT images results in increased doses administered to the patients, but also provides further diagnostic information contained in the volumetric images. The assessed CBCT protocols provide images that are noisy, but with

  6. Multi-Fresnel lenses pumping approach for improving high-power Nd:YAG solar laser beam quality.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana

    2013-07-20

    To significantly improve the present-day high-power solar laser beam quality, a three-stage multi-Fresnel lenses approach is proposed for side-pumping either a Nd:YAG single-crystal or a core-doped Sm(3+)Nd:YAG ceramic rod. Optimum pumping and laser beam parameters are found through ZEMAX and LASCAD numerical analysis. The proposed scheme offers a uniform absorption profile along the rod. 167 W laser power can be achieved, corresponding to 29.3 W/m(2) collection efficiency. High brightness figure of merit of 8.34 W is expected for the core-doped rod within a convex-concave resonator, which is 1300 times higher than that of the most-recent high-power solar laser.

  7. Comparison of Different Numerical Methods for Quality Factor Calculation of Nano and Micro Photonic Cavities

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza; Mørk, Jesper; Chung, Il-Sug

    2014-01-01

    Four different numerical methods for calculating the quality factor and resonance wavelength of a nano or micro photonic cavity are compared. Good agreement was found for a wide range of quality factors. Advantages and limitations of the different methods are discussed.......Four different numerical methods for calculating the quality factor and resonance wavelength of a nano or micro photonic cavity are compared. Good agreement was found for a wide range of quality factors. Advantages and limitations of the different methods are discussed....

  8. TU-FG-BRB-12: Real-Time Visualization of Discrete Spot Scanning Proton Therapy Beam for Quality Assurance

    International Nuclear Information System (INIS)

    Matsuzaki, Y; Jenkins, C; Yang, Y; Xing, L; Yoshimura, T; Fujii, Y; Umegaki, K

    2016-01-01

    Purpose: With the growing adoption of proton beam therapy there is an increasing need for effective and user-friendly tools for performing quality assurance (QA) measurements. The speed and versatility of spot-scanning proton beam (PB) therapy systems present unique challenges for traditional QA tools. To address these challenges a proof-of-concept system was developed to visualize, in real-time, the delivery of individual spots from a spot-scanning PB in order to perform QA measurements. Methods: The PB is directed toward a custom phantom with planar faces coated with a radioluminescent phosphor (Gd2O2s:Tb). As the proton beam passes through the phantom visible light is emitted from the coating and collected by a nearby CMOS camera. The images are processed to determine the locations at which the beam impinges on each face of the phantom. By so doing, the location of each beam can be determined relative to the phantom. The cameras are also used to capture images of the laser alignment system. The phantom contains x-ray fiducials so that it can be easily located with kV imagers. Using this data several quality assurance parameters can be evaluated. Results: The proof-of-concept system was able to visualize discrete PB spots with energies ranging from 70 MeV to 220 MeV. Images were obtained with integration times ranging from 20 to 0.019 milliseconds. If not limited by data transmission, this would correspond to a frame rate of 52,000 fps. Such frame rates enabled visualization of individual spots in real time. Spot locations were found to be highly correlated (R"2=0.99) with the nozzle-mounted spot position monitor indicating excellent spot positioning accuracy Conclusion: The system was shown to be capable of imaging individual spots for all clinical beam energies. Future development will focus on extending the image processing software to provide automated results for a variety of QA tests.

  9. TU-FG-BRB-12: Real-Time Visualization of Discrete Spot Scanning Proton Therapy Beam for Quality Assurance

    Energy Technology Data Exchange (ETDEWEB)

    Matsuzaki, Y [Proton Beam Therapy Center, Hokkaido University Hospital, Sapporo, Hokkaido (Japan); Jenkins, C; Yang, Y; Xing, L [Stanford University, Stanford, California (United States); Yoshimura, T; Fujii, Y [Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido (Japan); Umegaki, K [Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Hokkaido (Japan)

    2016-06-15

    Purpose: With the growing adoption of proton beam therapy there is an increasing need for effective and user-friendly tools for performing quality assurance (QA) measurements. The speed and versatility of spot-scanning proton beam (PB) therapy systems present unique challenges for traditional QA tools. To address these challenges a proof-of-concept system was developed to visualize, in real-time, the delivery of individual spots from a spot-scanning PB in order to perform QA measurements. Methods: The PB is directed toward a custom phantom with planar faces coated with a radioluminescent phosphor (Gd2O2s:Tb). As the proton beam passes through the phantom visible light is emitted from the coating and collected by a nearby CMOS camera. The images are processed to determine the locations at which the beam impinges on each face of the phantom. By so doing, the location of each beam can be determined relative to the phantom. The cameras are also used to capture images of the laser alignment system. The phantom contains x-ray fiducials so that it can be easily located with kV imagers. Using this data several quality assurance parameters can be evaluated. Results: The proof-of-concept system was able to visualize discrete PB spots with energies ranging from 70 MeV to 220 MeV. Images were obtained with integration times ranging from 20 to 0.019 milliseconds. If not limited by data transmission, this would correspond to a frame rate of 52,000 fps. Such frame rates enabled visualization of individual spots in real time. Spot locations were found to be highly correlated (R{sup 2}=0.99) with the nozzle-mounted spot position monitor indicating excellent spot positioning accuracy Conclusion: The system was shown to be capable of imaging individual spots for all clinical beam energies. Future development will focus on extending the image processing software to provide automated results for a variety of QA tests.

  10. Generation and application of soft-X-ray by means of inverse compton scattering between high quality election beam and IR laser

    International Nuclear Information System (INIS)

    Washio, M.; Sakaue, K.; Hama, Y.; Kamiya, Y.; Moriyama, R.; Hezume, K.; Saito, T.; Kuroda, R.; Kashiwagi, S.; Ushida, K.; Hayano, H.; Urakawa, J.

    2006-01-01

    High quality beam generation project based on High-Tech Research Center Project, which has been approved by Ministry of Education, Culture, Sports, Science and Technology in 1999, has been conducted by advance research institute for science and engineering, Waseda University. In the project, laser photo-cathode RF-gun has been selected for the high quality electron beam source. RF cavities with low dark current, which were made by diamond turning technique, have been successfully manufactured. The low emittance electron beam was realized by choosing the modified laser injection technique. The obtained normalized emittance was about 3 mm·mrad at 100 pC of electron charge. The soft X-ray beam generation with the energy of 370 eV, which is in the energy region of so-called 'water window', by inverse Compton scattering has been performed by the collision between IR laser and the low emittance electron beams. (authors)

  11. Application of electron-beam irradiation combined with antioxidants for fermented sausage and its quality characteristic

    International Nuclear Information System (INIS)

    Lim, D.G.; Seol, K.H.; Jeon, H.J.; Jo, C.; Lee, M.

    2008-01-01

    The effects of various doses of electron-beam irradiation on the changes in microbiological attributes of fermented sausage and the combined effect of electron-beam irradiation and various antioxidants on the oxidative stability and sensory properties during cold storage were investigated. Results indicated that 2 kGy of irradiation was the most effective in manufacturing a fermented sausage, and the addition of rosemary extracts was effective in controlling the production of off-flavor and development of lipid oxidation during cold storage

  12. Application of electron-beam irradiation combined with antioxidants for fermented sausage and its quality characteristic

    Science.gov (United States)

    Lim, D. G.; Seol, K. H.; Jeon, H. J.; Jo, C.; Lee, M.

    2008-06-01

    The effects of various doses of electron-beam irradiation on the changes in microbiological attributes of fermented sausage and the combined effect of electron-beam irradiation and various antioxidants on the oxidative stability and sensory properties during cold storage were investigated. Results indicated that 2 kGy of irradiation was the most effective in manufacturing a fermented sausage, and the addition of rosemary extracts was effective in controlling the production of off-flavor and development of lipid oxidation during cold storage.

  13. THE INSPECTION LIKE QUALITY FACTOR IN THE EDUCATIONAL SYSTEM

    Directory of Open Access Journals (Sweden)

    Joaquín Oliver Pozo

    2016-07-01

    Full Text Available The Inspection, along with other educational sectors, shapes from complementarity, coordination and communication between them, the architecture of the educational system. Each has its specificity and its own space in Education. The aim of this study is simply identify and define the location of the inspection into the education system, between educational administration and schools, and the "why" (their mission, and consistent with it, "which makes" (its functions and assignations. Mission and functions that take place in schools, at the sight of the Educational Administration and the society, through the Inspectorate as organization. Of the principles underlying this organization and of the communication, training, and technical and professional exchange that drives through their organizational structures, will depend its leadership in Education and to be seen as a quality factor.

  14. High quality factor HTS Josephson junctions on low loss substrates

    Energy Technology Data Exchange (ETDEWEB)

    Stornaiuolo, D; Longobardi, L; Massarotti, D; Barone, A; Tafuri, F [CNR-SPIN Napoli, Complesso Universitario di Monte Sant' Angelo, via Cinthia, 80126 Napoli (Italy); Papari, G; Carillo, F [NEST, CNR-NANO and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy); Cennamo, N [Dipartimento Ingegneria dell' Informazione, Seconda Universita degli Studi di Napoli, via Roma 29, 81031 Aversa (Italy)

    2011-04-15

    We have extended the off-axis biepitaxial technique to produce YBCO grain boundary junctions on low loss substrates. Excellent transport properties have been reproducibly found, with remarkable values of the quality factor I{sub c}R{sub n} (with I{sub c} the critical current and R{sub n} the normal state resistance) above 10 mV, far higher than the values commonly reported in the literature for high temperature superconductor (HTS) based Josephson junctions. The outcomes are consistent with a picture of a more uniform grain boundary region along the current path. This work supports a possible implementation of grain boundary junctions for various applications including terahertz sensors and HTS quantum circuits in the presence of microwaves.

  15. [Quality-of-life-related factors in adolescents].

    Science.gov (United States)

    Lima-Serrano, Marta; Martínez-Montilla, José Manuel; Guerra-Martín, María Dolores; Vargas-Martínez, Ana Magdalena; Lima-Rodríguez, Joaquín S

    To determine quality of life (QoL) and its relationship to lifestyles in adolescents in high schools. Cross-sectional, observational study with 256 students aged 12 to 17 in Seville (Spain). Multiple linear regression models were tested (p <0.05). The boys had higher scores in most of the QoL areas. The female gender was inversely related to physical, psychological, familial QoL areas and the general QoL index. Family functionality and performing physical activity were the factors most associated with better QoL in all areas. All multivariate models were statistically significant and explained from 11% of social QoL variability to 35% of the general QoL index. The findings could be useful for developing interventions to promote health in schools, with the objective of promoting healthy lifestyles and QoL. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Estimating Depolarization with the Jones Matrix Quality Factor

    Science.gov (United States)

    Hilfiker, James N.; Hale, Jeffrey S.; Herzinger, Craig M.; Tiwald, Tom; Hong, Nina; Schöche, Stefan; Arwin, Hans

    2017-11-01

    Mueller matrix (MM) measurements offer the ability to quantify the depolarization capability of a sample. Depolarization can be estimated using terms such as the depolarization index or the average degree of polarization. However, these calculations require measurement of the complete MM. We propose an alternate depolarization metric, termed the Jones matrix quality factor, QJM, which does not require the complete MM. This metric provides a measure of how close, in a least-squares sense, a Jones matrix can be found to the measured Mueller matrix. We demonstrate and compare the use of QJM to other traditional calculations of depolarization for both isotropic and anisotropic depolarizing samples; including non-uniform coatings, anisotropic crystal substrates, and beetle cuticles that exhibit both depolarization and circular diattenuation.

  17. Analysis of factors affecting the LOCA test quality

    International Nuclear Information System (INIS)

    Wang Lu

    2008-01-01

    Localization of nuclear safety-related equipment has become an important way of nuclear power development in China. To meet this demand, the competence should be promoted in the following two areas, one is to develop the capability of R and D and manufacturing of nuclear safety-related equipment, the other is to implement equipment qualification according to relevant codes and standards. As LOCA test is one of the most important parts in the qualification test of nuclear safety-related equipment, the main factors related with the quality of the LOCA test are analyzed in this paper, and this may be a reference to improve the skills in designing, constructing and operating LOCA test devices. (authors)

  18. Sci-Thur AM: YIS – 04: Stopping power-to-Cherenkov power ratios and beam quality specification for clinical Cherenkov emission dosimetry of electrons: beam-specific effects and experimental validation

    International Nuclear Information System (INIS)

    Zlateva, Yana; Seuntjens, Jan; El Naqa, Issam

    2016-01-01

    Purpose: To advance towards clinical Cherenkov emission (CE)-based dosimetry by investigating beam-specific effects on Monte Carlo-calculated electron-beam stopping power-to-CE power ratios (SCRs), addressing electron beam quality specification in terms of CE, and validating simulations with measurements. Methods: The EGSnrc user code SPRRZnrc, used to calculate Spencer-Attix stopping-power ratios, was modified to instead calculate SCRs. SCRs were calculated for 6- to 22-MeV clinical electron beams from Varian TrueBeam, Clinac 21EX, and Clinac 2100C/D accelerators. Experiments were performed with a 20-MeV electron beam from a Varian TrueBeam accelerator, using a diffraction grating spectrometer with optical fiber input and a cooled back-illuminated CCD. A fluorophore was dissolved in the water to remove CE signal anisotropy. Results: It was found that angular spread of the incident beam has little effect on the SCR (≤ 0.3% at d max ), while both the electron spectrum and photon contamination increase the SCR at shallow depths and decrease it at large depths. A universal data fit of R 50 in terms of C 50 (50% CE depth) revealed a strong linear dependence (R 2 > 0.9999). The SCR was fit with a Burns-type equation (R 2 = 0.9974, NRMSD = 0.5%). Below-threshold incident radiation was found to have minimal effect on beam quality specification (< 0.1%). Experiments and simulations were in good agreement. Conclusions: Our findings confirm the feasibility of the proposed CE dosimetry method, contingent on computation of SCRs from additional accelerators and on further experimental validation. This work constitutes an important step towards clinical high-resolution out-of-beam CE dosimetry.

  19. Sci-Thur AM: YIS – 04: Stopping power-to-Cherenkov power ratios and beam quality specification for clinical Cherenkov emission dosimetry of electrons: beam-specific effects and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Zlateva, Yana; Seuntjens, Jan; El Naqa, Issam [McGill University, Cedars Cancer Centre, University of Michigan (United States)

    2016-08-15

    Purpose: To advance towards clinical Cherenkov emission (CE)-based dosimetry by investigating beam-specific effects on Monte Carlo-calculated electron-beam stopping power-to-CE power ratios (SCRs), addressing electron beam quality specification in terms of CE, and validating simulations with measurements. Methods: The EGSnrc user code SPRRZnrc, used to calculate Spencer-Attix stopping-power ratios, was modified to instead calculate SCRs. SCRs were calculated for 6- to 22-MeV clinical electron beams from Varian TrueBeam, Clinac 21EX, and Clinac 2100C/D accelerators. Experiments were performed with a 20-MeV electron beam from a Varian TrueBeam accelerator, using a diffraction grating spectrometer with optical fiber input and a cooled back-illuminated CCD. A fluorophore was dissolved in the water to remove CE signal anisotropy. Results: It was found that angular spread of the incident beam has little effect on the SCR (≤ 0.3% at d{sub max}), while both the electron spectrum and photon contamination increase the SCR at shallow depths and decrease it at large depths. A universal data fit of R{sub 50} in terms of C{sub 50} (50% CE depth) revealed a strong linear dependence (R{sup 2} > 0.9999). The SCR was fit with a Burns-type equation (R{sup 2} = 0.9974, NRMSD = 0.5%). Below-threshold incident radiation was found to have minimal effect on beam quality specification (< 0.1%). Experiments and simulations were in good agreement. Conclusions: Our findings confirm the feasibility of the proposed CE dosimetry method, contingent on computation of SCRs from additional accelerators and on further experimental validation. This work constitutes an important step towards clinical high-resolution out-of-beam CE dosimetry.

  20. Factors affecting quality of social interaction park in Jakarta

    Science.gov (United States)

    Mangunsong, N. I.

    2018-01-01

    The existence of social interactions park in Jakarta is an oasis in the middle of a concrete jungle. Parks is a response to the need for open space as a place of recreation and community interaction. Often the social interaction parks built by the government does not function as expected, but other functions such as a place to sell, trash, unsafe so be rarely visited by visitors. The purpose of this study was to analyze the factors that affect the quality of social interaction parks in Jakarta by conducting descriptive analysis and correlation analysis of the variables assessment. The results of the analysis can give an idea of social interactions park based on community needs and propose the development of social interactioncity park. The object of study are 25 social interaction parks in 5 municipalities of Jakarta. The method used is descriptive analysis method, correlation analysis using SPSS 19 and using crosstab, chi-square tests. The variables are 5 aspects of Design, Plants composition: Selection type of plant (D); the beauty and harmony (Ind); Maintenance and fertility (P); Cleanliness and Environmental Health (BS); Specificity (Drainage, Multi Function garden, Means, Concern/Mutual cooperation, in dense settlements) (K). The results of analysis show that beauty is the most significant correlation with the value of the park followed by specificity, cleanliness and maintenance. Design was not the most significant variable affecting the quality of the park. The results of this study can be used by the Department of Parks and Cemeteries as input in managing park existing or to be developed and to improve the quality of social interaction park in Jakarta.

  1. Gamma radiation influence on internal quality factors of eggs

    International Nuclear Information System (INIS)

    Pombo, Carolina R.; Mano, Sergio B.

    2005-01-01

    Poultry egg is a fundamental item in the human diet due to its high nutritional value. Its treatment by irradiation in order to eliminate pathogenic bacteria has been authorized in the USA in 2000 limited to a dose of 3 kGy in contrast to the requirements of the Brazilian legislation that does not establish quantitative dose limits. However research on the sensory properties of irradiated eggs is still scarce in the literature. In this work, possible changes in the internal quality factors of eggs were investigated. The samples were irradiated with doses of 0, 0.5, 1.0, 1.5, 2.0 and 2.5 kGy at an average dose rate of 1.7 kGy/h in the research Cesium-137 irradiation facility at the Technological Center of the Army (CTEx) situated in Guaratiba, Rio de Janeiro (RJ). A total of 300 eggs sorted in 6 lots, one for each dose, were kept at room temperature being periodically inspected up to 20 days. The samples were analyzed for the following indicators of the internal quality of the eggs: Haugh unity, air chamber, yolk index, pH of the white and pH of the yolk. The results indicated that irradiation damages the structure of the white of the eggs reducing its consistency in addition to changing other parameters related to their internal quality. Therefore, it has been concluded that irradiation is not appropriate for the treatment of whole eggs in the conditions studied in this work. (author)

  2. Social factors affecting education quality of Iranian medical & dental students.

    Science.gov (United States)

    Zafarmand, A Hamid; Sabour, Siamak

    2014-09-01

    Positive social behavior of student is an important factor in the integrity of educational quality. Unbalanced behavior can disrupt the progress of students in learning. The present study evaluates the effect of social factors on education quality of dental and medical students. This descriptive cross-sectional study was conducted on 227 randomly selected students (109 dental and 118 medical). The questionnaire contained three domains of cultural collectivism, self-concept, and social adjustment adapted from California Test of Personality. It also included demographic questions like; field of study, gender and home city of residence. Data was analyzed using SPSS (version#19) software. Pearsons' correlation coefficient and independent t-test were used at the P-value of 0.05. Generally, girl students showed higher cultural collectivism (P=0.028) and social adjustment (P=0.04). On the contrary, boys were better in self-concept behavior (P=0.34). Home city of residence evidenced with no significant effect on any aspects of social attitudes of subjects. Pearsons' correlation coefficient test showed a weak correlation between cultural collectivism and self-concept (r=0.134, P=0.04) and between cultural collectivism and social adjustment, as well. (r=0.252, P=0.001) Independent t-test showed a significant difference between male and female students concerning cultural collectivism and social adjustment. Reliability of cultural collectivism, self-concept and social adjustment scales ranged from very good to moderate, α=0.83, α=0.63, and α=0.54 respectively. The results of this study indicated that female students show better cultural collectivism and social adjustment skills. It also proved that home city of residence has no significant effect upon social behavior of either medical or dental students.

  3. Evaluation of ion chamber dependent correction factors for ionisation chamber dosimetry in proton beams using a Monte Carlo method

    International Nuclear Information System (INIS)

    Palmans, H.; Verhaegen, F.

    1995-01-01

    In the last decade, several clinical proton beam therapy facilities have been developed. To satisfy the demand for uniformity in clinical (routine) proton beam dosimetry two dosimetry protocols (ECHED and AAPM) have been published. Both protocols neglect the influence of ion chamber dependent parameters on dose determination in proton beams because of the scatter properties of these beams, although the problem has not been studied thoroughly yet. A comparison between water calorimetry and ionisation chamber dosimetry showed a discrepancy of 2.6% between the former method and ionometry following the ECHED protocol. Possibly, a small part of this difference can be attributed to chamber dependent correction factors. Indications for this possibility are found in ionometry measurements. To allow the simulation of complex geometries with different media necessary for the study of those corrections, an existing proton Monte Carlo code (PTRAN, Berger) has been modified. The original code, that applies Mollire's multiple scattering theory and Vavilov's energy straggling theory, calculates depth dose profiles, energy distributions and radial distributions for pencil beams in water. Comparisons with measurements and calculations reported in the literature are done to test the program's accuracy. Preliminary results of the influence of chamber design and chamber materials on dose to water determination are presented

  4. Evaluation of ion chamber dependent correction factors for ionisation chamber dosimetry in proton beams using a Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Palmans, H [Ghent Univ. (Belgium). Dept. of Biomedical Physics; Verhaegen, F

    1995-12-01

    In the last decade, several clinical proton beam therapy facilities have been developed. To satisfy the demand for uniformity in clinical (routine) proton beam dosimetry two dosimetry protocols (ECHED and AAPM) have been published. Both protocols neglect the influence of ion chamber dependent parameters on dose determination in proton beams because of the scatter properties of these beams, although the problem has not been studied thoroughly yet. A comparison between water calorimetry and ionisation chamber dosimetry showed a discrepancy of 2.6% between the former method and ionometry following the ECHED protocol. Possibly, a small part of this difference can be attributed to chamber dependent correction factors. Indications for this possibility are found in ionometry measurements. To allow the simulation of complex geometries with different media necessary for the study of those corrections, an existing proton Monte Carlo code (PTRAN, Berger) has been modified. The original code, that applies Mollire`s multiple scattering theory and Vavilov`s energy straggling theory, calculates depth dose profiles, energy distributions and radial distributions for pencil beams in water. Comparisons with measurements and calculations reported in the literature are done to test the program`s accuracy. Preliminary results of the influence of chamber design and chamber materials on dose to water determination are presented.

  5. Improved image quality of cone beam CT scans for radiotherapy image guidance using fiber-interspaced antiscatter grid.

    Science.gov (United States)

    Stankovic, Uros; van Herk, Marcel; Ploeger, Lennert S; Sonke, Jan-Jakob

    2014-06-01

    Medical linear accelerator mounted cone beam CT (CBCT) scanner provides useful soft tissue contrast for purposes of image guidance in radiotherapy. The presence of extensive scattered radiation has a negative effect on soft tissue visibility and uniformity of CBCT scans. Antiscatter grids (ASG) are used in the field of diagnostic radiography to mitigate the scatter. They usually do increase the contrast of the scan, but simultaneously increase the noise. Therefore, and considering other scatter mitigation mechanisms present in a CBCT scanner, the applicability of ASGs with aluminum interspacing for a wide range of imaging conditions has been inconclusive in previous studies. In recent years, grids using fiber interspacers have appeared, providing grids with higher scatter rejection while maintaining reasonable transmission of primary radiation. The purpose of this study was to evaluate the impact of one such grid on CBCT image quality. The grid used (Philips Medical Systems) had ratio of 21:1, frequency 36 lp/cm, and nominal selectivity of 11.9. It was mounted on the kV flat panel detector of an Elekta Synergy linear accelerator and tested in a phantom and a clinical study. Due to the flex of the linac and presence of gridline artifacts an angle dependent gain correction algorithm was devised to mitigate resulting artifacts. Scan reconstruction was performed using XVI4.5 augmented with inhouse developed image lag correction and Hounsfield unit calibration. To determine the necessary parameters for Hounsfield unit calibration and software scatter correction parameters, the Catphan 600 (The Phantom Laboratory) phantom was used. Image quality parameters were evaluated using CIRS CBCT Image Quality and Electron Density Phantom (CIRS) in two different geometries: one modeling head and neck and other pelvic region. Phantoms were acquired with and without the grid and reconstructed with and without software correction which was adapted for the different acquisition

  6. Improved image quality of cone beam CT scans for radiotherapy image guidance using fiber-interspaced antiscatter grid

    International Nuclear Information System (INIS)

    Stankovic, Uros; Herk, Marcel van; Ploeger, Lennert S.; Sonke, Jan-Jakob

    2014-01-01

    Purpose: Medical linear accelerator mounted cone beam CT (CBCT) scanner provides useful soft tissue contrast for purposes of image guidance in radiotherapy. The presence of extensive scattered radiation has a negative effect on soft tissue visibility and uniformity of CBCT scans. Antiscatter grids (ASG) are used in the field of diagnostic radiography to mitigate the scatter. They usually do increase the contrast of the scan, but simultaneously increase the noise. Therefore, and considering other scatter mitigation mechanisms present in a CBCT scanner, the applicability of ASGs with aluminum interspacing for a wide range of imaging conditions has been inconclusive in previous studies. In recent years, grids using fiber interspacers have appeared, providing grids with higher scatter rejection while maintaining reasonable transmission of primary radiation. The purpose of this study was to evaluate the impact of one such grid on CBCT image quality. Methods: The grid used (Philips Medical Systems) had ratio of 21:1, frequency 36 lp/cm, and nominal selectivity of 11.9. It was mounted on the kV flat panel detector of an Elekta Synergy linear accelerator and tested in a phantom and a clinical study. Due to the flex of the linac and presence of gridline artifacts an angle dependent gain correction algorithm was devised to mitigate resulting artifacts. Scan reconstruction was performed using XVI4.5 augmented with inhouse developed image lag correction and Hounsfield unit calibration. To determine the necessary parameters for Hounsfield unit calibration and software scatter correction parameters, the Catphan 600 (The Phantom Laboratory) phantom was used. Image quality parameters were evaluated using CIRS CBCT Image Quality and Electron Density Phantom (CIRS) in two different geometries: one modeling head and neck and other pelvic region. Phantoms were acquired with and without the grid and reconstructed with and without software correction which was adapted for the different

  7. Producing National Ignition Facility (NIF)-quality beams on the Nova and Beamlet lasers

    International Nuclear Information System (INIS)

    Widmayer, C.C.; Auerbach, J.M.; Ehrlich, R.B.

    1996-08-01

    The Nova and Beamlet lasers were used to simulate the beam propagation conditions that will be encountered during the National Ignition Facility operation. Perturbation theory predicts that there is a 5mm scale length propagation mode that experiences large nonlinear power growth. This mode was observed in the tests. Further tests have confirmed that this mode can be suppressed with improved spatial filtering

  8. Simulations of Beam Quality in a 13 MeV PET Cyclotron

    Directory of Open Access Journals (Sweden)

    A. Pramudita

    2015-12-01

    Full Text Available Simulation of the trajectories of negative hydrogen ion (H− beam in a 13 MeV PET cyclotron (DECY-13 were carried out by using the Runge-Kutta (RK4 approximation method and Scilab 5.4.1. The magnetic and electric fields were calculated using Opera-3d/TOSCA softwares at 1 mm resolution. The cyclotron is of a fourth-harmonics type, meaning that the acceleration occurs four times per cycle, with a radiofrequency (RF field of 77.66 MHz frequency and 40 kV amplitude. The calculations and simulations show that the maximum distance between the ion source and the puller is about 6 mm, while the maximum width of the beam at 13 MeV is about 10 mm, and the initial phase between the RF field and the beam ranges from -10° to 10°, with a yield of about 10% of the beam from the ion source getting accelerated to 13 MeV.

  9. Influence of external beam technique and brachytherapy quality assurance on the side effects in the combined external beam- and brachytherapy treatment of local advanced prostate cancer

    International Nuclear Information System (INIS)

    Kovacs, G.; Galalae, R.; Wirth, B.; Bertermann, H.; Wilhelm, R.; Kohr, P.; Kimmig, B.

    1996-01-01

    Transrectal ultrasound(TRUS) guided HDR implantation of the prostate has been established at the Kiel University by Bertermann and Brix in 1986 and there are to date 179 (T1b-T3 No Mo) patients treated in a combined modality. The dose for the implant was 2x 15 Gy on the capsule of the prostate in 14-20 days. For local and regional lymph nodes 20 Gy external beam therapy (AP-PA pelvic portals), 20 Gy with an individual transmission block (100% for subclinical disease, 70% and 50% according to the implant dosimetry for the prostate) and 10 Gy small volume irradiation for the prostate was applied, conventional fractioned. Total dose after the therapy 70 Gy for the prostate and 50 Gy for the subclinical disease in 6-7 weeks. As a quality control method we use since 1991 in vivo dosimetry on the medial rectum wall as well as in the prostatic part of the urethra. Regular follow-up 3-118 months after therapy (median 55) with PSA, digital rectal examination, control TRUS with volumetry (after one year with biopsy) and bone scan. There were no major early side effects within the first three months. Proctitis till 1991 with a duration up to 12 months 49%, prolonging more than one year in 23 %, (total proctitis 72.6%). Dysuria in up to 12 months 30 %, long lasting 30% (total number of dysuria 60 %). Erectile dysfunction in 56 %. Because of the number of the side effects 1991 we changed the external beam technique: instead of the biaxial arch therapy the AP-PA portals, and reduced irradiated volume (from 6480 cm 3 to 5040 cm 3 ). We introduced instead of the small volume arch therapy for 10 Gy external boost the box-technique with shielding the back part of the rectum and the upper part of the bladder resulting additional volume reduction. Through the 15 Gy HDR brachytherapy dose on the prostate capsule there are up to 8 Gy on the medial rectal wall, measured by in vivo dosimetry. This dose could not be responsible for the high number of side effects (see gynecological

  10. Investigation on working quality of laser beam cutting of composite materials. Final report. Untersuchung der Bearbeitungsgenauigkeit und Prozessfuehrung beim Laserstrahlschneiden von Verbundwerkstoffen und Werkstoffverbunden. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, M.; Mueller, R.

    1992-01-01

    Expanded use of composite materials often requires a cutting process to reach the desired shape of the work piece. In conventional mechanical cutting technologies like milling remarcable tool wear has to be considered due to the containing glass fibers which have a tremendous abrasive effect on the tool teeth. Here the laser beam is an alternative 'tool'. With this investigations the knowledge about the parameters of laser beam cutting of composites which determine working quality was increased. Requirements for an optimal cutting process and fundamental correlations between process parameters and working quality are presented. In absence of suitable criterions to estimate the working quality of laser beam cut composite materials, a suggestion of a DIN 2310, Part 7, 'Thermal Cutting, Laser Beam Cutting of Composites' is presented. (orig.) With 69 refs., 125 figs.

  11. Experimental investigation of the characteristics of a laser beam passing through a fluid layer for surface quality in-process measurement

    International Nuclear Information System (INIS)

    Guo, Ruipeng; Tao, Zhengsu

    2010-01-01

    The optical characteristics of a laser beam passing through a fluid parallel layer are examined through a series of experimental tests in this project. The experimental apparatus consists of a bare surface quality measurement system and a fluid-supporting system. In the case of laser beam propagation through the static fluid layer, a modified Beckmann–Kirchhoff scattering model has been developed. Based on this model, the results of the surface quality in-process optical measurement can be amended. By extracting a ratio parameter from the image of the scattered light pattern to estimate surface roughness, the modified model can be verified quantitatively in the experimental system. As far as laser beam propagation through the flowing fluid layer is concerned, the deflection of the laser beam caused by fluid flow is small. The experiments are conducted to investigate the characteristics, and the results show that the resulting measurement error for surface quality optical measurement is in an acceptable range

  12. [Quality of life and related influencing factors in Chinese adults].

    Science.gov (United States)

    Deng, Q; Wang, L M; Zhang, M

    2016-02-01

    To evaluate the quality of life (QOL) and influencing factors on Chinese adults. 83 666 subjects from 2010 Chronic Non-communicable Disease and Risk Factor Surveillance Project in China were included in this study. Questionnaire was used to collect information on general condition and health status. WHOQOL-BREF was adopted as an instrument to measure the QOL on all the subjects.t test was used to compare QOL from different groups. Multiple linear regression analysis was used to assess the association of QOL with BMI, by gender. Among all the 83 666 subjects, mean scores of physical,psychological, social relationship and environment domains appeared as (73.97 ± 13.84), (66.65 ± 14.21), (65.76 ± 14.08) and (56.59 ± 15.15), respectively. Age, residential areas (urban/rural), education levels and marital status all showed significant impact on scores of the four domains (Peducation level (Peducation levels, marital status and chronic diseases could significantly influence the QOL of Chinese adults.

  13. SU-E-I-52: Effect of Various X-Ray Beam Qualities On the Exposure Index

    International Nuclear Information System (INIS)

    Yasumatsu, S; Iwase, K; Shimizu, Y; Tanaka, N; Morishita, J

    2015-01-01

    Purpose: The exposure index (EI) proposed by the International Electrotechnical Commission (IEC) 62494-1 is expected to be utilized as a standard dose index by every manufacturer. The IEC recommended the usage of RQA5 for the EI. However, X-ray beam qualities, particularly in clinical practices, vary depending on the examination objects and exposure conditions, including usage of anti-scatter grids. We investigated the effects of the X-ray beam qualities other than RQA5 on the EI. Methods: The Xray beam qualities of RQA3, 5, 7, and 9 in IEC 61267 Ed. 1.0 were adopted in a computed radiography system. A uniform exposure without objects was performed to measure the exposure indicators (S values) and air kerma (K). The relational equations between the S values and K were derived for the determination of the EI values. The EI values for RQA3, 7, and 9 were compared to those for RQA5 at the fixed S values of 100, 200, 400, and 600. Finally, the half-value layers (HVLs) using four grids (ratio 6:1, 8:1, 10:1, and 12:1) for the RQA5 X-ray were compared to those with RQA3–9. Results: The EI values for RQA3, 7, and 9 were up to 35.3%, 11.8%, and 38.7% higher, respectively, than that for RQA5 at the S value of 600. The HVLs without grids and with various grids for RQA5 were 6.85 mm Al. and in the range of 6.94–7.29 mm Al. (ΔHVL: up to 0.44 mm Al.), respectively. This variation in the HVLs with grids was smaller than that observed for RQA3–9 (ΔHVL: 2.0–7.5 mm Al.). Conclusion: Although the usage of grids may not greatly affect the EI, the X-ray beam quality for the determination of the EI cannot be ignored in the clinical evaluation of the dose index

  14. Moderator/collimator for a proton/deuteron linac to produce a high-intensity, high-quality thermal neutron beam for neutron radiography

    International Nuclear Information System (INIS)

    Singleterry, R.C. Jr.; Imel, G.R.; McMichael, G.E.

    1995-01-01

    Reactor based high resolution neutron radiography facilities are able to deliver a well-collimated (L/D ≥100) thermal flux of 10 6 n/cm 2 ·sec to an image plane. This is well in excess of that achievable with the present accelerator based systems such as sealed tube D-T sources, Van der Graaff's, small cyclotrons, or low duty factor linacs. However, continuous wave linacs can accelerate tens of milliamperes of protons to 2.5 to 4 MeV. The MCNP code has been used to analyze target/moderator configurations that could be used with Argonne's Continuous Wave Linac (ACWL). These analyses have shown that ACWL could be modified to generate a neutron beam that has a high intensity and is of high quality

  15. SU-E-T-554: Comparison of Electron Disequilibrium Factor in External Photon Beams for Different Models of Linear Accelerators

    International Nuclear Information System (INIS)

    LIU, B; Zhu, T

    2014-01-01

    Purpose: The dose in the buildup region of a photon beam is usually determined by the transport of the primary secondary electrons and the contaminating electrons from accelerator head. This can be quantified by the electron disequilibrium factor, E, defined as the ratio between total dose and equilibrium dose (proportional to total kerma), E = 1 in regions beyond buildup region. Ecan be different among accelerators of different models and/or manufactures of the same machine. This study compares E in photon beams from different machine models/ Methods: Photon beam data such as fractional depth dose curve (FDD) and phantom scatter factors as a function of field size and phantom depth were measured for different Linac machines. E was extrapolated from these fractional depth dose data while taking into account inverse-square law. The ranges of secondary electron were chosen as 3 and 6 cm for 6 and 15 MV photon beams, respectively. The field sizes range from 2x2 to 40x40 cm 2 . Results: The comparison indicates the standard deviations of electron contamination among different machines are about 2.4 - 3.3% at 5 mm depth for 6 MV and 1.2 - 3.9% at 1 cm depth for 15 MV for the same field size. The corresponding maximum deviations are 3.0 - 4.6% and 2 - 4% for 6 and 15 MV, respectively. Both standard and maximum deviations are independent of field sizes in the buildup region for 6 MV photons, and slightly decreasing with increasing field size at depths up to 1 cm for 15 MV photons. Conclusion: The deviations of electron disequilibrium factor for all studied Linacs are less than 3% beyond the depth of 0.5 cm for the photon beams for the full range of field sizes (2-40 cm) so long as they are from the same manufacturer

  16. Health-Related Quality of Life After Single-Fraction High-Dose-Rate Brachytherapy and Hypofractionated External Beam Radiotherapy for Prostate Cancer

    International Nuclear Information System (INIS)

    Morton, Gerard C.; Loblaw, D. Andrew; Chung, Hans; Tsang, Gail; Sankreacha, Raxa; Deabreu, Andrea; Zhang Liying; Mamedov, Alexandre; Cheung, Patrick; Batchelar, Deidre; Danjoux, Cyril; Szumacher, Ewa

    2011-01-01

    Purpose: To investigate the change in health-related quality of life for men after high-dose-rate brachytherapy and external beam radiotherapy for prostate cancer and the factors associated with this change. Methods and Materials: Eligible patients had clinically localized intermediate-risk prostate cancer. The patients received high-dose-rate brachytherapy as a single 15-Gy implant, followed by external beam radiotherapy to 37.5 Gy in 15 fractions. The patients were monitored prospectively for toxicity (Common Terminology Criteria for Adverse Events, version 3.0) and health-related quality of life (Expanded Prostate Cancer Index Composite [EPIC]). The proportion of patients developing a clinically significant difference in the EPIC domain score (minimally important difference of >0.5 standard deviation) was determined and correlated with the baseline clinical and dosimetric factors. The study accrued 125 patients, with a median follow-up of 24 months. Results: By 24 months, 23% had Grade 2 urinary toxicity and only 5% had Grade 2 bowel toxicity, with no Grade 3 toxicity. The proportion of patients reporting a significant decrease in EPIC urinary, bowel, sexual, and hormonal domain scores was 53%, 51%, 45%, and 40% at 12 months and 57%, 65%, 51%, and 30% at 24 months, respectively. The proportion with a >1 standard deviation decrease in the EPIC urinary, bowel, sexual, and hormonal domain scores was 38%, 36%, 24%, and 20% at 12 months and 46%, 48%, 19%, and 8% at 24 months, respectively. On multivariate analysis, the dose to 10% of the urethra was associated with a decreasing EPIC urinary domain score (p = .0089) and, less strongly (p = .0312) with a decreasing hormonal domain score. No association was found between the prostate volume, bladder dose, or high-dose volume and urinary health-related quality of life. A high baseline International Index of Erectile Function score was associated (p = .0019) with a decreasing sexual domain score. The optimal maximal dose

  17. Analysis of the penumbra enlargement in lung versus the Quality Index of photon beams: A methodology to check the dose calculation algorithm

    International Nuclear Information System (INIS)

    Tsiakalos, Miltiadis F.; Theodorou, Kiki; Kappas, Constantin; Zefkili, Sofia; Rosenwold, Jean-Claude

    2004-01-01

    It is well known that considerable underdosage can occur at the edges of a tumor inside the lung because of the degradation of penumbra due to lack of lateral electronic equilibrium. Although present even at smaller energies, this phenomenon is more pronounced for higher energies. Apart from Monte Carlo calculation, most of the existing Treatment Planning Systems (TPSs) cannot deal at all, or with acceptable accuracy, with this effect. A methodology has been developed for assessing the dose calculation algorithms in the lung region where lateral electronic disequilibrium exists, based on the Quality Index (QI) of the incident beam. A phantom, consisting of layers of polystyrene and lung material, has been irradiated using photon beams of 4, 6, 15, and 20 MV. The cross-plane profiles of each beam for 5x5, 10x10, and 25x10 fields have been measured at the middle of the phantom with the use of films. The penumbra (20%-80%) and fringe (50%-90%) enlargement was measured and the ratio of the widths for the lung to that of polystyrene was defined as the Correction Factor (CF). Monte Carlo calculations in the two phantoms have also been performed for energies of 6, 15, and 20 MV. Five commercial TPS's algorithms were tested for their ability to predict the penumbra and fringe enlargement. A linear relationship has been found between the QI of the beams and the CF of the penumbra and fringe enlargement for all the examined fields. Monte Carlo calculations agree very well (less than 1% difference) with the film measurements. The CF values range between 1.1 for 4 MV (QI 0.620) and 2.28 for 20 MV (QI 0.794). Three of the tested TPS's algorithms could not predict any enlargement at all for all energies and all fields and two of them could predict the penumbra enlargement to some extent. The proposed methodology can help any user or developer to check the accuracy of its algorithm for lung cases, based on a simple phantom geometry and the QI of the incident beam. This check is

  18. Effects of Electron Beam Irradiated Natural Casings on the Quality Characteristics of Emulsion Sausage

    International Nuclear Information System (INIS)

    Kim, Hyunwook; Kim, Hackyoun; Hwang, Koeun; Choi, Sunmi; Kim, Cheonjei; Choi, Jihun; Choi, Yunsang; Lee, Juwoon

    2011-01-01

    The effects of electron beam irradiated hog and sheep casings (1, 3, and 8 KGy) on the physicochemical properties and shelf stability of emulsion sausage were evaluated. There were no significantly differences in ph, instrumental color, and sensory evaluation among all the samples tested (p>0.05). The cooking yields for the irradiated treated samples were larger than the yields obtained for the non-irradiated samples for both the hog and sheep casing. However, the results on the purge loss after storage for 5 weeks were contradictory. The hardness of the sausage was lower when the irradiated natural casings were used. The irradiated natural casings accelerated lipid oxidation. The volatile basic nitrogen values were lower in samples treated with electron beam irradiation. The natural casings irradiated up to a dose of 3kGy not only had different total aerobic bacteria counts during the initial storage period but also displayed higher TAB counts at the final storage period

  19. Direct diode lasers with comparable beam quality to fiber, CO2, and solid state lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Kaiman, Michael; Overman, Robert; Glenn, John D.; Tayebati, Parviz

    2012-03-01

    TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers.

  20. Use of an optical digital reader for establishing criterion of quality control in clinical beams

    International Nuclear Information System (INIS)

    Genis S, R.

    1998-01-01

    The goal of this work is to present a procedure for realizing the control of the clinical radiation fields through typical radiographic film of verification in radiotherapy and showing the results of the analysis carried out in the expositions of reference fields for photons and electrons using an optical digital reader of high resolution (600 x 1200 dpi) named scanner and a computer program for images edition. It was possible to obtain the quantification of the following parameters: alinement of the radiation beam with the luminous beam, homogeneity or levelling of the radiation field, and self symmetry with respect to the center of the luminous field. With the purpose to compare the results versus an usual method it was realized measurements of the same images with a luminous photo densitometer with 1 mm collimation window. (Author)

  1. R & D of a Gas-Filled RF Beam Profile Monitor for Intense Neutrino Beam Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Yonehara, K. [Fermilab; Backfish, M. [Fermilab; Moretti, A. [Fermilab; Tollestrup, A. V. [Fermilab; Watts, A. [Fermilab; Zwaska, R. M. [Fermilab; Abrams, R. [MUONS Inc., Batavia; Cummings, M. A.; Dudas, A. [MUONS Inc., Batavia; Johnson, R. P. [MUONS Inc., Batavia; Kazakevich, G. [MUONS Inc., Batavia; Neubauer, M. [MUONS Inc., Batavia; Liu, Q. [Case Western Reserve U.

    2017-05-01

    We report the R&D of a novel radiation-robust hadron beam profile monitor based on a gas-filled RF cavity for intense neutrino beam experiments. An equivalent RF circuit model was made and simulated to optimize the RF parameter in a wide beam intensity range. As a result, the maximum acceptable beam intensity in the monitor is significantly increased by using a low-quality factor RF cavity. The plan for the demonstration test is set up to prepare for future neutrino beam experiments.

  2. Effect of photon-beam energy on VMAT and IMRT treatment plan quality and dosimetric accuracy for advanced prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Pasler, Marlies; Wirtz, Holger; Lutterbach, Johannes [Lake Constance Radiation Oncology Center Singen-Friedrichshafen, Singen (Germany); Georg, Dietmar [Medical Univ. Vienna (Austria). Dept. of Radiotherapy

    2011-12-15

    The goal of the research was to evaluate treatment plan quality and dosimetric accuracy of volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) plans using 6, 10, and 15 MV photon beams for prostate cancer including lymph nodes. In this retrospective study, VMAT and IMRT plans were generated with the Pinnacle {sup copyright} treatment planning system (TPS) (V9.0) for 10 prostate cancer cases. Each plan consisted of two target volumes: PTV{sub B} included the prostate bed, PTV{sub PC+LN} contained PTV{sub B} and lymph nodes. For plan evaluation statistics, the homogeneity index, conformity index, mean doses, and near-max doses to organs at risk (OAR) were analyzed. Treatment time and number of monitor units were assessed to compare delivery efficiency. Dosimetric plan verification was performed with a 2D ionization chamber array placed in a full scatter phantom. Results: No differences were found for target and OAR parameters in low and high energy photon beam plans for both VMAT and IMRT. A slightly higher low dose volume was detected for 6 MV VMAT plans (normal tissue: D{sub mean} = 16.47 Gy) compared to 10 and 15 MV VMAT plans (D{sub mean} = 15.90 Gy and 15.74 Gy, respectively), similar to the findings in IMRT. In VMAT, > 96% of detector points passed the 3%/ 3 mm {gamma} criterion; marginally better accuracy was found in IMRT (> 97%). Conclusion: For static and rotational IMRT, 15 MV photons did not show advantages over 6 and 10 MV high energy photon beams in large volume pelvic plans. For the investigated TPS and linac combination, 10 MV photon beams can be used as the general purpose energy for intensity modulation.

  3. Field quality in low-β superconducting quadrupoles and impact on the beam dynamics for the Large Hadron Collider upgrade

    Directory of Open Access Journals (Sweden)

    Boris Bellesia

    2007-06-01

    Full Text Available A possible scenario for the luminosity upgrade of the Large Hadron Collider is based on large aperture quadrupoles to lower β^{*} in the interaction regions. Here we analyze the measurements relative to the field quality of the RHIC and LHC superconducting quadrupoles to find out the dependence of field errors on the size of the magnet aperture. Data are interpreted in the framework of a Monte Carlo analysis giving the reproducibility in the coil positioning reached in each production. We show that this precision is likely to be independent of the magnet aperture. Using this result, we can carry out an estimate of the impact of the field quality on the beam dynamics for the collision optics.

  4. The local distribution of radiation quality of a collimated fast neutron beam from 15 MeV deuterons on beryllium

    International Nuclear Information System (INIS)

    Fidorra, J.; Booz, J.

    1978-01-01

    The local distribution of radiation quality (ysub(F), ysub(D)) of a collimated fast neutron beam from 14 MeV deuterons on Beryllium was studied with a spherical 1/2 inch EG and G proportional counter simulating a diameter of 2μm. The deuterons were accelerated by the compact cyclotron CV-28 of the Kernforschungsanlage Juelich. The collimator was constructed by the Cyclotron Corporation. The mean neutron energy was 6 MeV. The measurements were performed in air and in a water phantom at a target skin distance of 125 cm. The energy deposition spectra of fast neutrons obtained at various positions were separated into three components of different radiation quality: the gamma component, the recoil proton component, and the heavy ion component

  5. Dosimetric quality assurance of highly conformal external beam treatments: from 2D phantom comparisons to 4D patient dose reconstruction

    International Nuclear Information System (INIS)

    Feygelman, V; Nelms, B

    2013-01-01

    As IMRT technology continues to evolve, so do the dosimetric QA methods. A historical review of those is presented, starting with longstanding techniques such as film and ion chamber in a phantom and progressing towards 3D and 4D dose reconstruction in the patient. Regarding patient-specific QA, we envision that the currently prevalent limited comparison of dose distributions in the phantom by γ-analysis will be eventually replaced by clinically meaningful patient dose analyses with improved sensitivity and specificity. In a larger sense, we envision a future of QA built upon lessons from the rich history of ''quality'' as a science and philosophy. This future will aim to improve quality (and ultimately reduce cost) via advanced commissioning processes that succeed in detecting and rooting out systematic errors upstream of patient treatment, thus reducing our reliance on, and the resource burden associated with, per-beam/per-plan inspection.

  6. Dosimetric quality assurance of highly conformal external beam treatments: from 2D phantom comparisons to 4D patient dose reconstruction

    Science.gov (United States)

    Feygelman, V.; Nelms, B.

    2013-06-01

    As IMRT technology continues to evolve, so do the dosimetric QA methods. A historical review of those is presented, starting with longstanding techniques such as film and ion chamber in a phantom and progressing towards 3D and 4D dose reconstruction in the patient. Regarding patient-specific QA, we envision that the currently prevalent limited comparison of dose distributions in the phantom by γ-analysis will be eventually replaced by clinically meaningful patient dose analyses with improved sensitivity and specificity. In a larger sense, we envision a future of QA built upon lessons from the rich history of "quality" as a science and philosophy. This future will aim to improve quality (and ultimately reduce cost) via advanced commissioning processes that succeed in detecting and rooting out systematic errors upstream of patient treatment, thus reducing our reliance on, and the resource burden associated with, per-beam/per-plan inspection.

  7. Influence of substrate quality on structural properties of AlGaN/GaN superlattices grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, F. [NaMLab gGmbH, Nöthnitzer Straße 64, 01187 Dresden (Germany); Merkel, U.; Schmult, S. [TU Dresden, Institute of Semiconductors and Microsystems, Nöthnitzer Straße 64, 01187 Dresden (Germany); Mikolajick, T. [NaMLab gGmbH, Nöthnitzer Straße 64, 01187 Dresden (Germany); TU Dresden, Institute of Semiconductors and Microsystems, Nöthnitzer Straße 64, 01187 Dresden (Germany)

    2014-02-28

    Short-period AlGaN/GaN superlattices were established as versatile test structures to investigate the structural properties of molecular beam epitaxy (MBE)-grown GaN and AlGaN layers and their dependence on the GaN substrate quality. X-ray diffractometry data of the investigated superlattices allow access to relevant structural parameters such as aluminum mole fraction and layer thicknesses. The occurrence of theoretically predicted intense high-order satellite peaks and pronounced interface fringes in the diffraction pattern reflects abrupt interfaces and perfect 2-dimensional growth resulting in smooth surfaces. The data unambiguously demonstrate that the structural quality of the MBE grown layers is limited by the structural properties of the GaN substrate.

  8. Beam-Beam Effects

    International Nuclear Information System (INIS)

    Herr, W; Pieloni, T

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities

  9. Snacking patterns, diet quality, and cardiovascular risk factors in adults

    Science.gov (United States)

    2014-01-01

    Background The relationship of snacking patterns on nutrient intake and cardiovascular risk factors (CVRF) in adults is unknown. The aim of this study was to examine the associations of snacking patterns with nutrient intake, diet quality, and a selection of CVRF in adults participating in the 2001-2008 National Health and Nutrition Examination Survey. Methods 24-hour dietary recalls were used to determine intake and cluster analysis was used to identify the snacking patterns. Height and weight were obtained and the health indices that were evaluated included diastolic and systolic blood pressure, high density lipoprotein-cholesterol, low density lipoprotein cholesterol, triacylglycerides, blood glucose, and insulin. Results The sample was participants (n = 18,988) 19+ years (50% males; 11% African-Americans; 72% white, 12% Hispanic-Americans, and 5% other). Cluster analyses generated 12 distinct snacking patterns, explaining 61% of the variance in snacking. Comparisons of snacking patterns were made to the no snack pattern. It was found that miscellaneous snacks constituted the most common snacking pattern (17%) followed by cakes/cookies/pastries (12%) and sweets (9%). Most snacking patterns were associated with higher energy intakes. Snacking patterns cakes/cookies/pastries, vegetables/legumes, crackers/salty snacks, other grains and whole fruit were associated with lower intakes of saturated fatty acids. Added sugars intakes were higher in the cakes/cookies/pastries, sweets, milk desserts, and soft drinks patterns. Five snack patterns (cakes/cookies/pastries, sweets, vegetable/legumes, milk desserts, soft drinks) were associated with lower sodium intakes. Several snack patterns were associated with higher intakes of potassium, calcium, fiber, vitamin A, and magnesium. Five snacking patterns (miscellaneous snacks; vegetables/legumes; crackers/salty snacks; other grains; and whole fruit) were associated with better diet quality scores. Alcohol was associated with

  10. Improving beam spectral and spatial quality by double-foil target in laser ion acceleration for ion-driven fast ignition

    International Nuclear Information System (INIS)

    Huang, Chenkun; Albright, Brian J.

    2010-01-01

    Mid-Z ion driven fast ignition inertial fusion requires ion beams of 100s of MeV energy and < 10% energy spread. An overdense run-scale foil target driven by a high intensity laser pulse can produce an ion beam that has attractive properties for this application. The Break Out Afterburner (BOA) is one laser-ion acceleration mechanism proposed to generate such beams, however the late stages of the BOA tend to produce too large of an energy spread. The spectral and spatial qualities of the beam quickly evolve as the ion beam and co-moving electrons continue to interact with the laser. Here we show how use of a second target foil placed behind a nm-scale foil can substantially reduce the temperature of the co-moving electrons and improve the ion beam energy spread. Particle-In-Cell simulations reveal the dynamics of the ion beam under control. Optimal conditions for improving the spectral and spatial spread of the ion beam is explored for current laser and target parameters, leading to generation of ion beams of energy 100s of MeV and 6% energy spread, a vital step for realizing ion-driven fast ignition.

  11. CEBAF beam viewer imaging software

    International Nuclear Information System (INIS)

    Bowling, B.A.; McDowell, C.

    1993-01-01

    This paper discusses the various software used in the analysis of beam viewer images at CEBAF. This software, developed at CEBAF, includes a three-dimensional viewscreen calibration code which takes into account such factors as multiple camera/viewscreen rotations and perspective imaging, and maintaining a calibration database for each unit. Additional software allows single-button beam spot detection, with determination of beam location, width, and quality, in less than three seconds. Software has also been implemented to assist in the determination of proper chopper RF control parameters from digitized chopper circles, providing excellent results

  12. Factors Affecting Soil Quality Maintenance In Northern Katsina State

    African Journals Online (AJOL)

    programs or scientifically based soil management strategies. Soil quality ... envelopment analysis techniques in the reconciliation of two ..... integrated plant production and environmental quality. In ..... Handbook of Soil Science. (Ed). Sumner ...

  13. Factors associated with poor sleep quality in women with cancer.

    Science.gov (United States)

    Mansano-Schlosser, Thalyta Cristina; Ceolim, Maria Filomena

    2017-03-02

    to analyze the factors associated with poor sleep quality, its characteristics and components in women with breast cancer prior to surgery for removing the tumor and throughout the follow-up. longitudinal study in a teaching hospital, with a sample of 102 women. The following were used: a questionnaire for sociodemographic and clinical characterization, the Pittsburgh Sleep Quality Index; the Beck Depression Inventory; and the Herth Hope Scale. Data collection covered from prior to the surgery for removal of the tumor (T0) to T1, on average 3.2 months; T2, on average 6.1 months; and T3, on average 12.4 months. Descriptive statistics and the Generalized Estimating Equations model were used. depression and pain contributed to the increase in the score of the Pittsburgh Sleep Quality Index, and hope, to the reduction of the score - independently - throughout follow-up. Sleep disturbances were the component with the highest score throughout follow-up. the presence of depression and pain, prior to the surgery, contributed to the increase in the global score of the Pittsburgh Sleep Quality Index, which indicates worse quality of sleep throughout follow-up; greater hope, in its turn, influenced the reduction of the score of the Pittsburgh Sleep Quality Index. analizar los factores asociados a la mala calidad del sueño, sus características y componentes en mujeres con cáncer de mama, antes de la cirugía de retirada del tumor y a lo largo del seguimiento. estudio longitudinal, en hospital universitario con muestra de 102 mujeres. Fueron utilizados: un cuestionario de caracterización sociodemográfica y clínica; el Índice de Calidad del Sueño de Pittsburgh; el Inventario de Depresión de Beck; y la Escala de Esperanza de Herth. La recolección comprendió los momentos: antes de la cirugía de retirada del tumor (T0), en (T1) en promedio 3,2 meses, en (T2) en promedio 6,1 meses y en (T3) en promedio 12,4 meses. Se utilizó estadística descriptiva y el modelo de

  14. Structural fabrication quality as a factor of industrial facilities safety

    Science.gov (United States)

    Tishkov, E. V.; Kardaev, E. M.; Stolbova, S. Yu; Shishova, O. S.

    2018-04-01

    In the conditions of industrial facilities high wear degree, it is very important to ensure the possibility of their safe operation in order to avoid various kinds of accidents and catastrophes. As practice shows, industrial plant collapses can occur suddenly under normal operating conditions. Usually, such accidents can take place at different stages of structures life cycle. One of the reasons for this is the initially low quality of reinforced concrete structures fabrication. The article considers the factors contributing to the collapse of reinforced concrete structures of water purification tanks located on the territory of the Omsk Region. The main surveys results on tank structures after collapse with the use of ultrasonic and physical methods of investigation are presented. On the basis of the obtained data analysis, it was found that the main cause of the accidents was the insufficient load-bearing capacity of typical reinforced concrete structures, caused by defects in their fabrication in the factory conditions because of exceeding the standard displacement from the design position of the working reinforcement. Recommendations are given on the identification of defective structures and the prevention of similar accidents when operating similar tanks at manufacturing plants constructed from standard designs.

  15. Application of a newly developed software program for image quality assessment in cone-beam computed tomography.

    Science.gov (United States)

    de Oliveira, Marcus Vinicius Linhares; Santos, António Carvalho; Paulo, Graciano; Campos, Paulo Sergio Flores; Santos, Joana

    2017-06-01

    The purpose of this study was to apply a newly developed free software program, at low cost and with minimal time, to evaluate the quality of dental and maxillofacial cone-beam computed tomography (CBCT) images. A polymethyl methacrylate (PMMA) phantom, CQP-IFBA, was scanned in 3 CBCT units with 7 protocols. A macro program was developed, using the free software ImageJ, to automatically evaluate the image quality parameters. The image quality evaluation was based on 8 parameters: uniformity, the signal-to-noise ratio (SNR), noise, the contrast-to-noise ratio (CNR), spatial resolution, the artifact index, geometric accuracy, and low-contrast resolution. The image uniformity and noise depended on the protocol that was applied. Regarding the CNR, high-density structures were more sensitive to the effect of scanning parameters. There were no significant differences between SNR and CNR in centered and peripheral objects. The geometric accuracy assessment showed that all the distance measurements were lower than the real values. Low-contrast resolution was influenced by the scanning parameters, and the 1-mm rod present in the phantom was not depicted in any of the 3 CBCT units. Smaller voxel sizes presented higher spatial resolution. There were no significant differences among the protocols regarding artifact presence. This software package provided a fast, low-cost, and feasible method for the evaluation of image quality parameters in CBCT.

  16. H{sub 2}O{sub 2}-molecular beam epitaxy of high quality ZnO

    Energy Technology Data Exchange (ETDEWEB)

    El Shaer, A.; Bakin, A.; Che Mofor, A.; Kreye, M.; Waag, A. [Technical University Braunschweig, Institute of Semiconductor Technology, Braunschweig (Germany); Blaesing, J.; Krost, A. [Otto-von-Guericke-University, Institute of Experimental Physics, Magdeburg (Germany); Stoimenos, J. [Aristotele University, Physics Department, Thessaloniki (Greece); Pecz, B. [Hungarian Academy of Sciences, Research Institute for Technical Physics and Materials Science, P.O. Box 49, Budapest (Hungary)

    2007-07-15

    We have studied the growth and characterization of ZnO epilayers on (0001)-sapphire by H{sub 2}O{sub 2}-molecular beam epitaxy (MBE). A high temperature (HT) MgO buffer followed by a low-temperature ZnO buffer was introduced in order to accommodate the lattice mismatch between ZnO and sapphire. The surface morphology of the samples was studied using atomic force microscopy (AFM), and scanning electron microscopy (SEM). The crystalline quality of the layers was investigated by employing high resolution X-ray diffractometry (HRXRD) and high resolution transmission electron microscopy (HRTEM). The electrical properties of the grown ZnO layers were studied by Hall-effect measurements in a standard van der Pauw configuration. The measured surface roughness for the best layers is as low as 0.26 nm rms. HRXRD measurements of the obtained ZnO layers show excellent quality of the single crystalline ZnO heteroepitaxially grown on (0001)-sapphire with a HT MgO buffer layers. The influence of the growth conditions on the crystalline quality is discussed. The FWHM of the HRXRD (0002) rocking curves measured for the 2-inch ZnO-on-sapphire is as low as 27 arcsec with a very high lateral homogeneity across the whole 2-inch ZnO epilayers. The results indicate that H{sub 2}O{sub 2}-MBE is a suitable technique to fabricate ZnO epilayers of very high quality. (orig.)

  17. Effect of Gamma Radiation and Electron Beam on Microbiological Quality and Protein Patterns of 4 Selected Beans

    International Nuclear Information System (INIS)

    Chookaew, S.; Eamsir, J.; Pewlong, W.; Sajjabut, S.

    2014-01-01

    The aim of the present study was to evaluate the effect of gamma ray and electron beam on microbiological quality and protein pattern of four selected beans: mung beans, soy beans, peanuts and black beans. All beans samples were exposed to irradiation at doses of 0, 0.5, 1, and 2 kGy before evaluated for their microbiological quality using AOAC method and protein analysis by gel electrophoresis. Results showed that the amount of bacteria, yeast and mold of irradiated mung beans and peanuts were reduced, whereas these microbiological quality values remained relatively the same for irradiated soy beans and black beans compared to non-irradiated samples. In terms of protein analysis, the protein patterns of the irradiated beans were of the same quality as the non-irradiated samples. To further tested the effect of irradiation on the bean's protein at higher doses, all four selected beans were exposed to gamma ray at 10, 50, 100, 150 and 200 kGy. We found that the protein patterns of mung beans, peanuts and black beans were altered at doses above 50 kGy.

  18. Application of a newly developed software program for image quality assessment in cone-beam computed tomography

    International Nuclear Information System (INIS)

    De Oliveira, Marcus Vinicius Linhares; Campos, Paulo Sergio Flores; Paulo, Graciano; Santos, Antonio Carvalho; Santos, Joana

    2017-01-01

    The purpose of this study was to apply a newly developed free software program, at low cost and with minimal time, to evaluate the quality of dental and maxillofacial cone-beam computed tomography (CBCT) images. A polymethyl methacrylate (PMMA) phantom, CQP-IFBA, was scanned in 3 CBCT units with 7 protocols. A macro program was developed, using the free software ImageJ, to automatically evaluate the image quality parameters. The image quality evaluation was based on 8 parameters: uniformity, the signal-to-noise ratio (SNR), noise, the contrast-to-noise ratio (CNR), spatial resolution, the artifact index, geometric accuracy, and low-contrast resolution. The image uniformity and noise depended on the protocol that was applied. Regarding the CNR, high-density structures were more sensitive to the effect of scanning parameters. There were no significant differences between SNR and CNR in centered and peripheral objects. The geometric accuracy assessment showed that all the distance measurements were lower than the real values. Low-contrast resolution was influenced by the scanning parameters, and the 1-mm rod present in the phantom was not depicted in any of the 3 CBCT units. Smaller voxel sizes presented higher spatial resolution. There were no significant differences among the protocols regarding artifact presence. This software package provided a fast, low-cost, and feasible method for the evaluation of image quality parameters in CBCT

  19. Application of a newly developed software program for image quality assessment in cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    De Oliveira, Marcus Vinicius Linhares; Campos, Paulo Sergio Flores [Federal Institute of Bahia, Salvador (Brazil); Paulo, Graciano; Santos, Antonio Carvalho; Santos, Joana [Coimbra Health School, Polytechnic Institute of Coimbra, Coimbra (Portugal)

    2017-06-15

    The purpose of this study was to apply a newly developed free software program, at low cost and with minimal time, to evaluate the quality of dental and maxillofacial cone-beam computed tomography (CBCT) images. A polymethyl methacrylate (PMMA) phantom, CQP-IFBA, was scanned in 3 CBCT units with 7 protocols. A macro program was developed, using the free software ImageJ, to automatically evaluate the image quality parameters. The image quality evaluation was based on 8 parameters: uniformity, the signal-to-noise ratio (SNR), noise, the contrast-to-noise ratio (CNR), spatial resolution, the artifact index, geometric accuracy, and low-contrast resolution. The image uniformity and noise depended on the protocol that was applied. Regarding the CNR, high-density structures were more sensitive to the effect of scanning parameters. There were no significant differences between SNR and CNR in centered and peripheral objects. The geometric accuracy assessment showed that all the distance measurements were lower than the real values. Low-contrast resolution was influenced by the scanning parameters, and the 1-mm rod present in the phantom was not depicted in any of the 3 CBCT units. Smaller voxel sizes presented higher spatial resolution. There were no significant differences among the protocols regarding artifact presence. This software package provided a fast, low-cost, and feasible method for the evaluation of image quality parameters in CBCT.

  20. Beam quality dependence of IAEA TLDs irradiated in a standardized geometry

    International Nuclear Information System (INIS)

    Nystroem, H.; Bera, P.; Nette, P.

    1994-01-01

    Since 1968, the International Atomic Energy Agency (IAEA) has operated a postal dose intercomparison service based on TLDs. This service has been giving dosimetric support to hospitals with 60 Co teletherapy units in developing countries. The increasing number of medical accelerators installed in developing countries prompted the IAEA to expand the service also to cover high energy X ray beams. For this purpose the energy dependence of the TLDs and a suitable correction procedure for their use were studied. This paper is a discussion of that study. 10 refs, 6 figs, 2 tabs

  1. Technical Note: Validation of halo modeling for proton pencil beam spot scanning using a quality assurance test pattern

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Liyong, E-mail: linl@uphs.upenn.edu; Huang, Sheng; Kang, Minglei; Solberg, Timothy D.; McDonough, James E.; Ainsley, Christopher G. [Department of Radiation Oncology, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104 (United States)

    2015-09-15

    Purpose: The purpose of this paper is to demonstrate the utility of a comprehensive test pattern in validating calculation models that include the halo component (low-dose tails) of proton pencil beam scanning (PBS) spots. Such a pattern has been used previously for quality assurance purposes to assess spot shape, position, and dose. Methods: In this study, a scintillation detector was used to measure the test pattern in air at isocenter for two proton beam energies (115 and 225 MeV) of two IBA universal nozzles (UN #1 and UN #2). Planar measurements were compared with calculated dose distributions based on the weighted superposition of location-independent (UN #1) or location-dependent (UN #2) spot profiles, previously measured using a pair-magnification method and between two nozzles. Results: Including the halo component below 1% of the central dose is shown to improve the gamma-map comparison between calculation and measurement from 94.9% to 98.4% using 2 mm/2% criteria for the 115 MeV proton beam of UN #1. In contrast, including the halo component below 1% of the central dose does not improve the gamma agreement for the 115 MeV proton beam of UN #2, due to the cutoff of the halo component at off-axis locations. When location-dependent spot profiles are used for calculation instead of spot profiles at central axis, the gamma agreement is improved from 98.0% to 99.5% using 2 mm/2% criteria. The two nozzles clearly have different characteristics, as a direct comparison of measured data shows a passing rate of 89.7% for the 115 MeV proton beam. At 225 MeV, the corresponding gamma comparisons agree better between measurement and calculation, and between measurements in the two nozzles. Conclusions: In addition to confirming the primary component of individual PBS spot profiles, a comprehensive test pattern is useful for the validation of the halo component at off-axis locations, especially for low energy protons.

  2. High quality factor gigahertz frequencies in nanomechanical diamond resonators

    OpenAIRE

    Gaidarzhy, Alexei; Imboden, Matthias; Mohanty, Pritiraj; Rankin, Janet; Sheldon, Brian W.

    2007-01-01

    We report actuation and detection of gigahertz-range resonance frequencies in nano-crystalline diamond mechanical resonators. High order transverse vibration modes are measured in coupled-beam resonators exhibiting frequencies up to 1.441 GHz. The cantilever-array design of the resonators translates the gigahertz-range resonant motion of micron-long cantilever elements to the displacement of the central supporting structure. Use of nano-crystalline diamond further increases the frequency comp...

  3. Effect of thermal lens on beam quality and mode matching in LD pumped Er-Yb-codoped phosphate glass microchip laser

    Energy Technology Data Exchange (ETDEWEB)

    Liu Shujing; Song Feng; Cai Hong; Li Teng; Tian Bin; Wu Zhaohui; Tian Jianguo [Photonics Center, Nankai University, Tianjin 300071 (China); Key Laboratory of Advanced Technique and Fabrication for Weak-Light Nonlinear Photonics Materials (Ministry of Education), Nankai University, Tianjin 300457 (China)

    2008-02-07

    The theoretical values of the thermal focal length and laser beam waist are derived from the theoretical model and transformation theory, respectively. The values of thermal focal length, laser beam waist and the far field divergence angle were experimentally measured in a laser diode (LD) pumped erbium-ytterbium(Er-Yb)-codoped phosphate microchip glass laser. As an extension of thermal effect studies, we investigate the role of thermal lens on beam quality and the mode matching between the pump and the laser, which affects laser efficiency in TEM{sub 00} operation. The study shows that the experimental data are in good agreement with the theoretical predictions.

  4. High-quality beam generation using an RF gun and a 150 MeV microtron

    Science.gov (United States)

    Kuroda, R.; Washio, M.; Kashiwagi, S.; Kobuki, T.; Ben-Zvi, I.; Wang, X. J.; Hori, T.; Sakai, F.; Tsunemi, A.; Urakawa, J.; Hirose, T.

    2000-11-01

    Low-emittance sub-picosecond electron pulses are expected to be used in a wide field, such as free electron laser, laser acceleration, femtosecond X-ray generation by Inverse Compton scattering, pulse radiolysis, etc. In order to produce the low-emittance sub-picosecond electron pulse, we are developing a compact Racetrack Microtron (RTM) with a new 5 MeV injection system adopting a laser photo cathode RF gun (Washio et al., Seventh China-Japan Bilateral Symposium on Radiation Chemistry, October 28, Cengdu, China, 1996). The operation of RTM has been kept under a steady state of beam loading for long pulse mode so far (Washio et al., J. Surf. Sci. Soc. Jpn. 19 (2) (1998) 23). In earlier work (Washio et al., PAC99, March 31, New York, USA, 1999), we have succeeded in the numerical simulation for the case of single short pulse acceleration. Finally, the modified RTM was demonstrated as a useful accelerator for a picosecond electron pulse generation under a transient state of beam loading. In the simulation, a picosecond electron pulse was accelerated to 149.6 MeV in RTM for the injection of 5 MeV electron bunch with a pulse length of 10 ps (FWHM), a charge of 1 nC per pulse, and an emittance of 3 πmm mrad.

  5. Evaluations of absorbed dose ratio factor of Al2O3 dosemeter in radiotherapy photon beams using cavity theory

    International Nuclear Information System (INIS)

    Zhu, J.; Chen, S.; Chen, L.; Liu, X.

    2012-01-01

    The aim of the work was to evaluate the absorbed dose ratio factor f md of an Al 2 O 3 dosemeter to water in photon radiotherapy beams using cavity theory. Burlin theory was used for calculating of this ratio. The effective mass attenuation coefficient β was obtained by comparing Monte Carlo simulations in monoenergetic photon beams. The evaluations of the absorbed dose ratio factor f md were studied for Al 2 O 3 dosemeters of different sizes, which were placed at various depths of the water phantom in different radiation field sizes of Mohan's 6, 10 and 15-MV X-rays. Beyond the build-up region, the variation of f md increases by 0.25 % as the depth increases from 4 to 10 cm. The maximum variation due to different dosemeter sizes is 8.3 %. The difference in the f md due to different radiation field sizes is 1.5 %. The effect of the dosemeter size cannot be neglected. The difference in the f md due to the radiation field sizes of different beams would increase as the dosemeter size increases. (authors)

  6. Detour factors in water and plastic phantoms and their use for range and depth scaling in electron-beam dosimetry

    International Nuclear Information System (INIS)

    Fernandez-Varea, J.M.; Andreo, P.; Tabata, T.

    1996-01-01

    Average penetration depths and detour factors of 1-50 MeV electrons in water and plastic materials have been computed by means of analytical calculation, within the continuous-slowing-down approximation and including multiple scattering, and using the Monte Carlo codes ITS and PENELOPE. Results are compared to detour factors from alternative definitions previously proposed in the literature. Different procedures used in low-energy electron-beam dosimetry to convert ranges and depths measured in plastic phantoms into water-equivalent ranges and depths are analysed. A new simple and accurate scaling method, based on Monte Carlo-derived ratios of average electron penetration depths and thus incorporating the effect of multiple scattering, is presented. Data are given for most plastics used in electron-beam dosimetry together with a fit which extends the method to any other low-Z plastic material. A study of scaled depth - dose curves and mean energies as a function of depth for some plastics of common usage shows that the method improves the consistency and results of other scaling procedures in dosimetry with electron beams at therapeutic energies. (author)

  7. Quality of Working Life of Nurses and its Related Factors

    OpenAIRE

    Moradi, Tayebeh; Maghaminejad, Farzaneh; Azizi-Fini, Ismail

    2014-01-01

    Background: Nurses as the largest group of health care providers should enjoy a satisfactory quality of working life to be able to provide quality care to their patients. Therefore, attention should be paid to the nurses’ working life. Objectives: This study aimed to investigate the quality of nurses' working life in Kashans' hospitals during 2012. Materials and Methods: This cross-sectional study was conducted on 200 nurses during 2012. The data-gathering instrument consisted of two parts. T...

  8. Establishing the standard X-ray beam qualities for calibration of dosimeters used in diagnostic radiology following IAEA-TRS457

    International Nuclear Information System (INIS)

    Duong Van Trieu; Ho Quang Tuan; Bui Duc Ky

    2014-01-01

    The determination of the patient dose needs to provide a reference dose for the patient that reference dose levels to assess the relative risk during X- ray diagnostic. This mission, We had established a number of standard beam qualities to perform calibrations of diagnostic dosimeters and methods of measuring patient dose in X-ray diagnostic. At radiation dosimetry room, we had establish RQR2, RQR3, RQR4, RQR5, RQR6 beam qualities based on IAEA-TRS457 documentation with homogeneity coefficient (h) for each beam quality in the range 0.7 - 0.8, and haft-value layers HVL1, HVL2 of experimental and IAEA is different about 10%. Established calibration method for diagnostic dosimeters as KAP meters, UNFORS dosimeters, and the TLD dosimeters, practical measurements of entrance surface air kerma on Shimadzu X-ray machines used phantom. (author)

  9. Quality assurance for multileaf collimator with radiographic film exposed by slit beam

    International Nuclear Information System (INIS)

    Ma Jinli; Jiang Guoliang; Fu Xiaolong; Liao Yuan; Wu Kailiang; Zhou Lijun

    2004-01-01

    Objective: To evaluate the role of Kodak X-OMAT-V film exposed by slit beam in the check of various leaf positions of multileaf collimator(MLC), and to check the status of Varian 26 leaf pairs MLC in the Department of Radiation Oncology in Shanghai Cancer Hospital affiliated to Fudan University. Methods: At first, some position errors of different sizes were produced for different leaves so as to determine the minimal leaf position error that could be seen on film. Then, exposure conditions including the exposure dose and source to film distance were changed to find the optimal one. Finally, a Kodak X-OMAT-V film was exposed with a leaf sequence file which was designated randomly by a physicist with leaf position errors of different sizes. After the film was developed, two doctors and two physicists were invited to observe, on blind basis, in order to determine the sensitivity and specificity of the film in the check of leaf positions. Ultimately, leaf positions of the Varian 26 leaf pairs MLC were checked, in which way, the leaf motor status and the carriage stability were checked indirectly. Results: Leaf position errors no less than 0.2 mm could be found using Kodak X-OMAT-V film under the following conditions: source to film distance 100 cm, exposure dose 25 MU, which had been considered as the optimal exposure conditions. The sensitivity and specificity of this method were 73.4% and 96.4%. Any MLC leaf position errors more than 0.2 mm could not be detected. Thus, it was deemed that all leaf motors of the Varian 26 leaf pairs MLC were well in gear and the carriages were stable. Conclusions: MLC leaf position errors can be detected by Kodak X-OMAT-V film exposed by slit beam with high accuracy, but the ability to find leaf position errors with the naked eye may vary from person to person. It is proposed that the Kodak X-OMAT-V film exposed by slit beam be used to check the MLC leaf positions, i. e. the leaf motor status and carriage stability, at regular

  10. On the Use of Quality Factor in Seismology (Invited)

    Science.gov (United States)

    Morozov, I. B.

    2009-12-01

    Despite its canonical character and widespread use in attenuation studies, suitability of the quality factor Q for describing the Earth still needs to be reviewed. Specifically, we need to consider the following fundamental questions: 1) How close is Q-1 to representing a true medium property? 2) Theoretically, can or should Q-1 be related to complex arguments of the elastic moduli of the medium? and 3) What attenuation property is typically measured and transformed into Q? An attempt for answering these questions shows that not Q but the spatial attenuation coefficient, α, represents a consistent property of energy dissipation by the medium which is also actually measured in most cases. Transformation of α into the apparent Q = πf/αV (V is the wave velocity and f - frequency) makes this Q a phenomenological attribute of the wave and also leads to its built-in positive frequency dependence. Such strong positive Q(f) is often reported, particularly for the “scattering Q,” but it may be entirely due to near-constant values of α. The above transformation is also prone of the well-known uncertainties related to the compensation of geometrical spreading (GS). Q can be adequately used to model wave amplitudes but it includes the effects of the structure (e.g., diving or reflected-wave GS) but becomes ambiguous when applied to describing the in-situ attenuation. By using α(f) in interpretation, such effects are explicitly measured, and several general observations can be made, such as: 1) α(f) often shows linear dependencies on f in both real data and modeling, whereas the corresponding Q(f) may be complex; 2) the zero-frequency limit of α(f)=γ can be interpreted as a generalized measure of geometrical spreading, and 3) frequency-dependent in-situ Q is not as widespread as it is commonly thought. Quantity γ is variable and correlates with tectonic age of the lithosphere, whereas the effective frequency-independent Qe is typically significantly higher than

  11. Quality of Life and Associated Factors of Cancer Patients in Malaysia: A review of current literature

    Directory of Open Access Journals (Sweden)

    Husna Ahmad Ainuddin

    2016-06-01

    Full Text Available Measuring quality of life provides information helpful for cancer patients. However, facts about the quality of life and its associated factors among cancer patients in Malaysia are inconclusive. The aim of this review of literature is to evaluate the quality of life of cancer patients and its associated factors. Based on this review of the literature, it identified 24 studies. Associated factors effecting quality of life of cancer patients include socio-demographic, health related, psychological and cancer treatment. In conclusion, there is a need for further research to focus on developing effective interventions to enhance the patients' quality of life.

  12. Factors Influencing Perceptions of Service Quality in Cooperative Extension Workers

    Science.gov (United States)

    Anaza, Nwamaka A.; Rutherford, Brian N.; Widdows, Richard

    2012-01-01

    The authors examined the direct and indirect impact of empowerment on service quality as perceived by Extension staff. Using a sample 283 respondents, the results revealed that along with empowerment, constructs such as job satisfaction and organizational identification positively affected service quality. Undoubtedly, each of these variables…

  13. Factors impacting on the microbiological quality and safety of ...

    African Journals Online (AJOL)

    hope&shola

    2010-12-06

    Dec 6, 2010 ... microbiological quality and safety of processed hake. Samples were collected along the processing line; the general microbiological quality (mesophylic and psychrotrophic aerobic plate counts), total. Vibrio species and common fish spoilage bacterial counts were performed. The results constantly showed ...

  14. Quality Management in Schools: Analysis of Mediating Factors

    Science.gov (United States)

    Díez, Fernando; Iraurgi, Ioseba; Sanchez, Aurelio Villa

    2018-01-01

    The objective of this study is to contribute to Quality Management Systems (QMS) and their impact on schools in the Basque Country, Spain. Specifically, it analyses two models: the EFQM Excellence Model, which originated in the business world, and the Integrated Quality Project (IQP) Model, which has a humanistic focus and arose from an…

  15. The Impact Factor: Implications of Open Access on Quality

    Science.gov (United States)

    Grozanick, Sara E.

    2010-01-01

    There has been debate about the extent to which open access affects the quality of scholarly work. At the same time, researchers have begun to look for ways to evaluate the quality of open access publications. Dating back to the growth of citation indexes during the 1960s and 1970s, citation analysis--examining citation statistics--has since been…

  16. Quality Instruction as a Motivating Factor in Higher Education

    Science.gov (United States)

    Sogunro, Olusegun A.

    2017-01-01

    The importance of quality instruction in motivating students in higher education cannot be overemphasized. Without quality instruction, students' motivation to learn recedes. Five focus groups of graduate students aided the data collection for this study. More than one-third of the 119 participating graduate students involved in this study claimed…

  17. WHAT FACTORS INFLUENCE QUALITY SERVICE IMPROVEMENT IN MONTENEGRO: EMPIRICAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Djurdjica Perovic

    2013-03-01

    Full Text Available In this paper, using an Ordinary Least Square regression (OLS, we investigate whether intangible elements influence tourist's perception about service quality. Our empirical results based on tourist survey in Montenegro, indicate that intangible elements of tourism product have positive impact on tourist's overall perception of service quality in Montenegro.

  18. Quality descriptors of optical beams based on centred reduced moments I: spot analysis

    International Nuclear Information System (INIS)

    Castaneda, Roman; Garcia-Sucerquia, Jorge; Brand, Frank

    2003-03-01

    A method for analyzing beam spots is discussed. It is based on the central reduced moments of the spot and its associated density functions. These functions allow us to separately analyze specific spot fractions, in such a way that specific combinations of higher order moments can be interpreted as coordinates of their centre of mass and the length and orientations of their principal axis. So, the descriptors of the associated density functions deal with the quantitative estimation of spot features, such as coma-like and astigmatism-like distortions. To assure high accuracy, background noise suppression and an optimal match of the spot support onto the region [-1,1]x[- 1,1] are performed prior to the calculation of the moments. Simulations were performed for illustrating the method. (author)

  19. Quality assessment and enhancement for cone-beam computed tomography in dental imaging

    International Nuclear Information System (INIS)

    Jeon, Sung Chae

    2006-02-01

    Cone-beam CT will become increasingly important in diagnostic imaging modality in the dental practice over the next decade. For dental diagnostic imaging, cone-beam computed tomography (CBCT) system based on large area flat panel imager has been designed and developed for three-dimensional volumetric image. The new CBCT system can provide a 3-D volumetric image during only one circular scanning with relatively short times (20-30 seconds) and requires less radiation dose than that of conventional CT. To reconstruct volumetric image from 2-D projection images, FDK algorithm was employed. The prototype of our CBCT system gives the promising results that can be efficiently diagnosed. This dissertation deals with assessment, enhancement, and optimization for dental cone-beam computed tomography with high performance. A new blur estimation method was proposed, namely model based estimation algorithm. Based on the empirical model of the PSF, an image restoration is applied to radiological images. The accuracy of the PSF estimation under Poisson noise and readout electronic noise is significantly better for the R-L estimator than the Wiener estimator. In the image restoration experiment, the result showed much better improvement in the low and middle range of spatial frequency. Our proposed algorithm is more simple and effective method to determine 2-D PSF of the x-ray imaging system than traditional methods. Image based scatter correction scheme to reduce the scatter effects was proposed. This algorithm corrects scatter on projection images based on convolution, scatter fraction, and angular interpolation. The scatter signal was estimated by convolving a projection image with scatter point spread function (SPSF) followed by multiplication with scatter fraction. Scatter fraction was estimated using collimator which is similar to SPECS method. This method does not require extra x-ray dose and any additional phantom. Maximum estimated error for interpolation was less than 7

  20. Quality descriptors of optical beams based on centred reduced moments I spot analysis

    CERN Document Server

    Castaneda, R; García-Sucerquia, J

    2003-01-01

    A method for analyzing beam spots is discussed. It is based on the central reduced moments of the spot and its associated density functions. These functions allow us to separately analyze specific spot fractions, in such a way that specific combinations of higher order moments can be interpreted as coordinates of their centre of mass and the length and orientations of their principal axis. So, the descriptors of the associated density functions deal with the quantitative estimation of spot features, such as coma-like and astigmatism-like distortions. To assure high accuracy, background noise suppression and an optimal match of the spot support onto the region [-1,1]x[- 1,1] are performed prior to the calculation of the moments. Simulations were performed for illustrating the method.

  1. Effect of electron beam irradiation on post harvest quality of Agaricus bisporus

    International Nuclear Information System (INIS)

    Zhang Juanpin; Xing Zengtao; Bai Bing; Song Weiguo

    2011-01-01

    The effects of electron beam irradiation on fresh-keeping of Agaricus bisporus was studied after sporecarp samples were irradiated at 1.0, 2.0, 3.0 and 4.0 kGy and then stored at 4 degree C for 14d. The contents of water-soluble vitamins, amino acids and sugars were measured. Results showed that the contents of water-soluble sugars, amino acids, and aneurin, lactochrome, nicotinic acid in sporecarp did not significantly change after irradiation. However, asoribic acid was sensitive to irradiation, and the content was significantly reduced 31.1% at the dose of 4.0 kGy. It is concluded that 2 kGy irradiation can effectively prolong the shelf life, and almost no significant effect on the nutrient components of Agaricus bisporus. (authors)

  2. CRITERIA AND FACTORS THAT INSURE THE QUALITY IN PROVISION OF AUDIT SERVICES, DIFFERENT FROM AUDIT

    Directory of Open Access Journals (Sweden)

    Antoniuk O.

    2018-03-01

    Full Text Available Introduction. Quality management of audit services requires further theoretical research and development in the field of audit activity and quality of audit, continuous improvement of the organization and methodology in providing audit services. Purpose. The article deals with the theoretical and practical questions of assessing the quality of audit services that are different from the audit in order to identify ways to improve the methodological quality assurance in the provision of these services. Results. It is proved that factors (economic, methodological, organizational and conditions have an impact on the quality of audit services. This, in general, affects the content of audit services regulation and their social and economic significance. The terms of quality assurance, which are considered in the article, have a decisive influence on the implementation of those specific factors that directly change the properties of the audit services and create the services of the required quality. Assurance of the quality of audit services is considered as the creation of the necessary conditions for the implementation of all factors that affect the quality of audit services, maintanence of the given level of quality of audit services in accordance with the requirements of legal acts and market needs. Conclusions. The issue of identifying criteria, factors and indicators for assessing the quality in audit services is raised. In the generalized form, the matrix of quality assurance of audit services is presented, which indicates the interconnection of various conditions, factors, quality indicators in audit services.

  3. Effects of electron beam irradiated natural casings on the quality properties and shelf stability of emulsion sausage

    International Nuclear Information System (INIS)

    Kim, Hyun-Wook; Choi, Ji-Hun; Choi, Yun-Sang; Kim, Hack-Youn; Hwang, Ko-Eun; Song, Dong-Heon; Lee, Ju-Woon; Kim, Cheon-Jei

    2012-01-01

    The effect of electron beam irradiated hog and sheep casings (1, 3, and 8 kGy) on the physicochemical properties and shelf stability of emulsion sausage was evaluated. There were no significant differences in pH, instrumental color, sensory properties (overall acceptability), and hardness between all the samples. The cooking yields for the irradiated treated samples were larger than that of the yields obtained for the non-irradiated samples for both the hog and sheep casing. The irradiated natural casings accelerated lipid oxidation, and inhibited the formation of volatile basic nitrogen and the increase in total aerobic bacteria. In conclusion, the natural casings irradiated below at a dose of 3 kGy had no effect on physicochemical and sensory properties of the emulsion sausages, however, that improved the shelf-stability over 5 weeks. Therefore, natural casings irradiated at moderate doses are suitable for sausage production. - Highlights: ► The effect of E-beam irradiated natural casings on sausage quality was evaluated. ► The use of irradiated casings improved shelf stability of sausage. ► Natural casings irradiated below 3 kGy are suitable for sausage production.

  4. Development of a one-stop beam verification system using electronic portal imaging devices for routine quality assurance

    International Nuclear Information System (INIS)

    Lim, Sangwook; Ma, Sun Young; Jeung, Tae Sig; Yi, Byong Yong; Lee, Sang Hoon; Lee, Suk; Cho, Sam Ju; Choi, Jinho

    2012-01-01

    In this study, a computer-based system for routine quality assurance (QA) of a linear accelerator (linac) was developed by using the dosimetric properties of an amorphous silicon electronic portal imaging device (EPID). An acrylic template phantom was designed such that it could be placed on the EPID and be aligned with the light field of the collimator. After irradiation, portal images obtained from the EPID were transferred in DICOM format to a computer and analyzed using a program we developed. The symmetry, flatness, field size, and congruence of the light and radiation fields of the photon beams from the linac were verified simultaneously. To validate the QA system, the ion chamber and film (X-Omat V2; Kodak, New York, NY) measurements were compared with the EPID measurements obtained in this study. The EPID measurements agreed with the film measurements. Parameters for beams with energies of 6 MV and 15 MV were obtained daily for 1 month using this system. It was found that our QA tool using EPID could substitute for the film test, which is a time-consuming method for routine QA assessment.

  5. Development of a one-stop beam verification system using electronic portal imaging devices for routine quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sangwook, E-mail: medicalphysics@hotmail.com [Department of Radiation Oncology, Kosin University College of Medicine, Seo-gu, Busan (Korea, Republic of); Ma, Sun Young; Jeung, Tae Sig [Department of Radiation Oncology, Kosin University College of Medicine, Seo-gu, Busan (Korea, Republic of); Yi, Byong Yong [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Lee, Sang Hoon [Department of Radiation Oncology, Cheil General Hospital and Women' s Healthcare Center, Kwandong University College of Medicine, Jung-gu, Seoul (Korea, Republic of); Lee, Suk [Department of Radiation Oncology, College of Medicine, Korea University, Seongbuk-gu, Seoul (Korea, Republic of); Cho, Sam Ju [Department of Radiation Oncology, Eulji University School of Medicine, Eulji General Hospital, Nowon-gu, Seoul (Korea, Republic of); Choi, Jinho [Department of Radiation Oncology, Gachon University of Medicine and Science, Namdong-gu, Incheon (Korea, Republic of)

    2012-10-01

    In this study, a computer-based system for routine quality assurance (QA) of a linear accelerator (linac) was developed by using the dosimetric properties of an amorphous silicon electronic portal imaging device (EPID). An acrylic template phantom was designed such that it could be placed on the EPID and be aligned with the light field of the collimator. After irradiation, portal images obtained from the EPID were transferred in DICOM format to a computer and analyzed using a program we developed. The symmetry, flatness, field size, and congruence of the light and radiation fields of the photon beams from the linac were verified simultaneously. To validate the QA system, the ion chamber and film (X-Omat V2; Kodak, New York, NY) measurements were compared with the EPID measurements obtained in this study. The EPID measurements agreed with the film measurements. Parameters for beams with energies of 6 MV and 15 MV were obtained daily for 1 month using this system. It was found that our QA tool using EPID could substitute for the film test, which is a time-consuming method for routine QA assessment.

  6. Impact of chemical polishing on surface roughness and dimensional quality of electron beam melting process (EBM) parts

    Science.gov (United States)

    Dolimont, Adrien; Rivière-Lorphèvre, Edouard; Ducobu, François; Backaert, Stéphane

    2018-05-01

    Additive manufacturing is growing faster and faster. This leads us to study the functionalization of the parts that are produced by these processes. Electron Beam melting (EBM) is one of these technologies. It is a powder based additive manufacturing (AM) method. With this process, it is possible to manufacture high-density metal parts with complex topology. One of the big problems with these technologies is the surface finish. To improve the quality of the surface, some finishing operations are needed. In this study, the focus is set on chemical polishing. The goal is to determine how the chemical etching impacts the dimensional accuracy and the surface roughness of EBM parts. To this end, an experimental campaign was carried out on the most widely used material in EBM, Ti6Al4V. Different exposure times were tested. The impact of these times on surface quality was evaluated. To help predicting the excess thickness to be provided, the dimensional impact of chemical polishing on EBM parts was estimated. 15 parts were measured before and after chemical machining. The improvement of surface quality was also evaluated after each treatment.

  7. Development and implementation of a low-cost phantom for quality control in cone beam computed tomography

    International Nuclear Information System (INIS)

    Batista, W. O.; Navarro, M. V. T.; Maia, A. F.

    2013-01-01

    A phantom for quality control in cone beam computed tomography (CBCT) scanners was designed and constructed, and a methodology for testing was developed. The phantom had a polymethyl methacrylate structure filled with water and plastic objects that allowed the assessment of parameters related to quality control. The phantom allowed the evaluation of essential parameters in CBCT as well as the evaluation of linear and angular dimensions. The plastics used in the phantom were chosen so that their density and linear attenuation coefficient were similar to those of human facial structures. Three types of CBCT equipment, with two different technological concepts, were evaluated. The results of the assessment of the accuracy of linear and angular dimensions agreed with the existing standards. However, other parameters such as computed tomography number accuracy, uniformity and high-contrast detail did not meet the tolerances established in current regulations or the manufacturer's specifications. The results demonstrate the importance of establishing specific protocols and phantoms, which meet the specificities of CBCT. The practicality of implementation, the quality control test results for the proposed phantom and the consistency of the results using different equipment demonstrate its adequacy. (authors)

  8. Elaboration and implementation of standard operational procedure for quality assurance of cone beam CT image in radiotherapy

    International Nuclear Information System (INIS)

    Bonatto, Larisse N.; Estacio, Daniela R.; Lopes, Juliane S.; Sansson, Angela; Duarte, Lucas O.; Sbaraini, Patricia; Silva, Ana M. Marques da; Streck, Elaine E.

    2016-01-01

    The objective of this article is to present the implementation of the quality Control of Cone Beam Computed Tomography (CBCT) image, generated by the On-Board Imager, integrated with the linear accelerator Trilogy. Standard operating procedures (POPs) have been developed based on the literature and manuals of the simulator object Catphan 504 and the On-Board Imager. The following POPs were developed: acquisition of the CBCT image; linearity of CT number; uniformity; spatial resolution; low contrast resolution; spatial linearity; thickness of the cut. The validation of the elaborated procedures was done from an experimental acquisition of the simulator object. The results obtained in the validation of the POPs are in compliance with the parameters established by the manufacturer of the simulator object, as well as those obtained in the acceptance of the On-Board Imager device.

  9. Comparison of k Q factors measured with a water calorimeter in flattening filter free (FFF) and conventional flattening filter (cFF) photon beams

    Science.gov (United States)

    de Prez, Leon; de Pooter, Jacco; Jansen, Bartel; Perik, Thijs; Wittkämper, Frits

    2018-02-01

    Recently flattening filter free (FFF) beams became available for application in modern radiotherapy. There are several advantages of FFF beams over conventional flattening filtered (cFF) beams, however differences in beam spectra at the point of interest in a phantom potentially affect the ion chamber response. Beams are also non-uniform over the length of a typical reference ion chamber and recombination is usually larger. Despite several studies describing FFF beam characteristics, only a limited number of studies investigated their effect on k Q factors. Some of those studies predicted significant discrepancies in k Q factors (0.4% up to 1.0%) if TPR20,10 based codes of practice (CoPs) were to be used. This study addresses the question to which extent k Q factors, based on a TPR20,10 CoP, can be applied in clinical reference dosimetry. It is the first study that compares k Q factors measured directly with an absorbed dose to water primary standard in FFF-cFF pairs of clinical photon beams. This was done with a transportable water calorimeter described elsewhere. The measurements corrected for recombination and beam radial non-uniformity were performed in FFF-cFF beam pairs at 6 MV and 10 MV of an Elekta Versa HD for a selection of three different Farmer-type ion chambers (eight serial numbers). The ratio of measured k Q factors of the FFF-cFF beam pairs were compared with the TPR20,10 CoPs of the NCS and IAEA and the %dd(10) x CoP of the AAPM. For the TPR20,10 based CoPs differences less than 0.23% were found in k Q factors between the corresponding FFF-cFF beams with standard uncertainties smaller than 0.35%, while for the %dd(10) x these differences were smaller than 0.46% and within the expanded uncertainty of the measurements. Based on the measurements made with the equipment described in this study the authors conclude that the k Q factors provided by the NCS-18 and IAEA TRS-398 codes of practice can be applied for flattening filter free beams without

  10. Factors influencing quality of life in patients with active tuberculosis.

    Science.gov (United States)

    Marra, Carlo A; Marra, Fawziah; Cox, Victoria C; Palepu, Anita; Fitzgerald, J Mark

    2004-10-20

    With effective treatment strategies, the focus of tuberculosis (TB) management has shifted from the prevention of mortality to the avoidance of morbidity. As such, there should be an increased focus on quality of life (QoL) experienced by individuals being treated for TB. The objective of our study was to identify areas of QoL that are affected by active TB using focus groups and individual interviews. English, Cantonese, and Punjabi-speaking subjects with active TB who were receiving treatment were eligible for recruitment into the study. Gender-based focus group sessions were conducted for the inner city participants but individual interviews were conducted for those who came to the main TB clinic or were hospitalized. Facilitators used open-ended questions and participants were asked to discuss their experiences of being diagnosed with tuberculosis, what impact it had on their lives, issues around adherence to anti-TB medications and information pertaining to their experience with side effects to these medications. All data were audio-recorded, transcribed verbatim, and analyzed using constant comparative analysis. 39 patients with active TB participated. The mean age was 46.2 years (SD 18.4) and 62% were male. Most were Canadian-born being either Caucasian or Aboriginal. Four themes emerged from the focus groups and interviews. The first describes issues related to the diagnosis of tuberculosis and sub-themes were identified as 'symptoms', 'health care provision', and 'emotional impact'. The second theme discusses TB medication factors and the sub-themes identified were 'adverse effects', 'ease of administration', and 'adherence'. The third theme describes social support and functioning issues for the individuals with TB. The fourth theme describes health behavior issues for the individuals with TB and the identified sub-themes were "behavior modification" and "TB knowledge." Despite the ability to cure TB, there remains a significant impact on QOL. Since much

  11. Factors influencing quality of life in patients with active tuberculosis

    Directory of Open Access Journals (Sweden)

    Cox Victoria C

    2004-10-01

    Full Text Available Abstract Background With effective treatment strategies, the focus of tuberculosis (TB management has shifted from the prevention of mortality to the avoidance of morbidity. As such, there should be an increased focus on quality of life (QoL experienced by individuals being treated for TB. The objective of our study was to identify areas of QoL that are affected by active TB using focus groups and individual interviews. Methods English, Cantonese, and Punjabi-speaking subjects with active TB who were receiving treatment were eligible for recruitment into the study. Gender-based focus group sessions were conducted for the inner city participants but individual interviews were conducted for those who came to the main TB clinic or were hospitalized. Facilitators used open-ended questions and participants were asked to discuss their experiences of being diagnosed with tuberculosis, what impact it had on their lives, issues around adherence to anti-TB medications and information pertaining to their experience with side effects to these medications. All data were audio-recorded, transcribed verbatim, and analyzed using constant comparative analysis. Results 39 patients with active TB participated. The mean age was 46.2 years (SD 18.4 and 62% were male. Most were Canadian-born being either Caucasian or Aboriginal. Four themes emerged from the focus groups and interviews. The first describes issues related to the diagnosis of tuberculosis and sub-themes were identified as 'symptoms', 'health care provision', and 'emotional impact'. The second theme discusses TB medication factors and the sub-themes identified were 'adverse effects', 'ease of administration', and 'adherence'. The third theme describes social support and functioning issues for the individuals with TB. The fourth theme describes health behavior issues for the individuals with TB and the identified sub-themes were "behavior modification" and "TB knowledge." Conclusion Despite the ability to

  12. the quality factor in consumers' preference of textile fabrics

    African Journals Online (AJOL)

    DGS-FUTO

    2018-06-01

    Jun 1, 2018 ... Whereas one consumer may derive much utility from a particular brand of .... companies adopt a value model and provide higher quality for less money. ..... wrappers, the difference in consumers‟ rating is slight or marginal; ...

  13. Assessment of phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography.

    Science.gov (United States)

    Ludlow, John B; Walker, Cameron

    2013-12-01

    The increasing use of cone-beam computed tomography in orthodontics has been coupled with heightened concern about the long-term risks of x-ray exposure in orthodontic populations. An industry response to this has been to offer low-exposure alternative scanning options in newer cone-beam computed tomography models. Effective doses resulting from various combinations of field of view size and field location comparing child and adult anthropomorphic phantoms with the recently introduced i-CAT FLX cone-beam computed tomography unit (Imaging Sciences, Hatfield, Pa) were measured with optical stimulated dosimetry using previously validated protocols. Scan protocols included high resolution (360° rotation, 600 image frames, 120 kV[p], 5 mA, 7.4 seconds), standard (360°, 300 frames, 120 kV[p], 5 mA, 3.7 seconds), QuickScan (180°, 160 frames, 120 kV[p], 5 mA, 2 seconds), and QuickScan+ (180°, 160 frames, 90 kV[p], 3 mA, 2 seconds). Contrast-to-noise ratio was calculated as a quantitative measure of image quality for the various exposure options using the QUART DVT phantom. Child phantom doses were on average 36% greater than adult phantom doses. QuickScan+ protocols resulted in significantly lower doses than standard protocols for the child (P = 0.0167) and adult (P = 0.0055) phantoms. The 13 × 16-cm cephalometric fields of view ranged from 11 to 85 μSv in the adult phantom and 18 to 120 μSv in the child phantom for the QuickScan+ and standard protocols, respectively. The contrast-to-noise ratio was reduced by approximately two thirds when comparing QuickScan+ with standard exposure parameters. QuickScan+ effective doses are comparable with conventional panoramic examinations. Significant dose reductions are accompanied by significant reductions in image quality. However, this trade-off might be acceptable for certain diagnostic tasks such as interim assessment of treatment results. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc

  14. Human Factors in Software Development Processes: Measuring System Quality

    DEFF Research Database (Denmark)

    Abrahão, Silvia; Baldassarre, Maria Teresa; Caivano, Danilo

    2016-01-01

    Software Engineering and Human-Computer Interaction look at the development process from different perspectives. They apparently use very different approaches, are inspired by different principles and address different needs. But, they definitively have the same goal: develop high quality software...... in the most effective way. The second edition of the workshop puts particular attention on efforts of the two communities in enhancing system quality. The research question discussed is: who, what, where, when, why, and how should we evaluate?...

  15. Gingivitis, Psychological Factors and Quality of Life in Children.

    Science.gov (United States)

    da Silva, Priscila de Lima; Barbosa, Taís de Souza; Amato, Juliana Neide; Montes, Ana Bheatriz Marangoni; Gavião, Maria Beatriz Duarte

    2015-01-01

    To evaluate the associations between gingivitis, emotional status and quality of life in children. Sixty-four Brazilian students (11 to 12 years old) were examined for clinical and self-reported gingivitis. The participants were divided into two groups: those with gingivitis (n = 21) and controls (n = 43). Quality of life, anxiety and depression were measured using self-administered questionnaires. Saliva was collected 30 min after waking and at bedtime to measure the diurnal decline in salivary cortisol. The results were analysed using bivariate and multivariate analyses. There were significantly more female participants in the control group. Approximately 90% of the children with gingivitis had good oral hygiene and 10.5% had satisfactory oral hygiene. There was a significant positive correlation between anxiety and depression in both clinical groups. Anxiety was negatively correlated with quality of life in the control group. Depression was negatively correlated with quality of life and cortisol concentrations in the group with gingivitis, and with quality of life in the control group. Children with gingivitis were more likely to be older and males. Older children are more likely to experience gingival bleeding. The presence of gingivitis in children may be associated with worse psychological well-being, possibly compromising the quality of life.

  16. Characterization of the crystalline quality of β-SiC formed by ion beam synthesis

    International Nuclear Information System (INIS)

    Intarasiri, S.; Hallen, A.; Kamwanna, T.; Yu, L.D.; Possnert, G.; Singkarat, S.

    2006-01-01

    The ion beam synthesis (IBS) technique is applied to form crystalline silicon carbide (SiC) for future optoelectronics applications. Carbon ions at 80 and 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at room temperature and 400 deg. C, respectively, to doses in excess of 10 17 ions/cm 2 . Subsequent thermal annealing of the implanted samples was performed in a vacuum furnace at temperatures of 800, 900 and 1000 deg. C, respectively. Elastic recoil detection analysis was used to investigate depth distributions of the implanted ions and infrared transmittance (IR) measurement was used to characterize formation of SiC in the implanted Si substrate. Complementary to IR, Raman scattering measurements were also carried out. Levels of the residual damage distribution of the samples annealed at different temperatures were compared with that of the as-implanted one by Rutherford backscattering spectrometry (RBS) in the channeling mode. The results show that C-ion implantation at the elevated temperature, followed by high-temperature annealing, enhances the synthesis of crystalline SiC

  17. Improving the beam quality of rf guns by correction of rf and space-charge effects

    International Nuclear Information System (INIS)

    Serafini, L.

    1992-01-01

    In this paper we describe two possible strategies to attain ultra-low emittance electron beam generation by laser-driven RF guns. The first one is based on the exploitation of multi-mode resonant cavities to neutralize the emittance degradation induced by RF effects. Accelerating cigar-like (long and thin) electron bunches in multi-mode operated RF guns the space charge induced emittance is strongly decreased at the same time: high charged bunches, as typically requested by future TeV e - e + colliders, can be delivered by the gun at a quite low transverse emittance and good behaviour in the longitudinal phase space, so that they can be magnetically compressed to reach higher peak currents. The second strategy consists in using disk-like electron bunches, produced by very short laser pulses illuminating the photocathode. By means of an analytical study a new regime has been found, where the normalized transverse emittance scales like the inverse of the peak current, provided that the laser pulse intensity distribution is properly shaped in the transverse direction. Preliminary numerical simulations confirm the analytical predictions and show that the minimum emittance achievable is set up, in this new regime, by the wake-field interaction between the bunch and the cathode metallic wall

  18. The characterization of high quality multicrystalline silicon by the electron beam induced current method

    International Nuclear Information System (INIS)

    Chen, J; Sekiguchi, T; Nara, S; Yang, D

    2004-01-01

    Multicrystalline silicon (mc-Si) manufactured by a multi-stage solidification control casting method has been characterized by the electron beam induced current (EBIC) method. The average diffusion length of the ingot was over 250 μm, which was much longer than that of conventional mc-Si. The EBIC study revealed that the electrical activities of grain boundaries (GBs) varied with the ingot position due to the impurity contamination level. The main impurity detected was iron. The concentration of iron in the central position was much lower than that at the bottom and top positions. GBs in the central position showed no significant EBIC contrast at 300 K, suggesting low contamination level. GBs in the top and bottom positions, however, showed strong EBIC contrast at 300 K, suggesting high contamination level. At 100 K, a denuded zone with bright contrast developed around GBs in the top and bottom positions. The existence of the denuded zone suggested that impurities were gettered at the GBs. It was considered that the variation of the diffusion length in the ingot was related to the variation of recombination activities of GBs in the different positions, which mainly depended on the impurity contamination

  19. Evaluation of technical quality and periapical health of root-filled teeth by using cone-beam CT

    Directory of Open Access Journals (Sweden)

    Bilge Gülsüm NUR

    2014-12-01

    Full Text Available Objective This study aimed to assess the quality of root fillings, coronal restorations, complications of all root-filled teeth and their association with apical periodontitis (AP detected by cone-beam computed tomography (CBCT images from an adult Turkish subpopulation. Material and Methods The sample for this study consisted of 242 patients (aging from 15 to 72 years with 522 endodontically treated teeth that were assessed for technical quality of the root canal filling and periapical status of the teeth. Additionally, the apical status of each root-filled tooth was assessed according to the gender, dental arch, tooth type and age classification, undetected canals, instrument fracture, root fracture, apical resorption, apical lesion, furcation lesion and type and quality of the coronal structure. Statistical analysis was performed using percentages and chi-square test. Results The success rate of the root canal treatment was of 54.4%. The success rates of adequate and inadequate root canal treatment were not significantly different (p>0.05. Apical periodontitis was found in 228 (45.6% teeth treated for root canals. Higher prevalence of AP was found in patients aging from 20 to 29 years [64 (27% teeth] and in anterior (canines and incisors teeth [97 (41% teeth]. Conclusions The technical quality of root canal filling performed by dental practitioners in a Turkish subpopulation was consistent with a high prevalence of AP. The probable reasons for this failure are multifactorial, and there may be a need for improved undergraduate education and postgraduate courses to improve the clinical skills of dental practitioners in endodontics.

  20. Standard operating procedures for quality audits of 60Co external beam radiotherapy facilities

    International Nuclear Information System (INIS)

    Larrinaga Cortina, E.F.; Dominguez Hung, L.; Campa Menendez, R.

    2001-01-01

    The use of radiotherapy implies the necessity of rigorous quality standards in its different components, aimed to provide the best possible treatment and avoid potential patients' risks, that could even cause him death. Projects of technical cooperation developed in Cuba and supported by the International Atomic Energy Agency address the implementation of Programs of Quality Assurance (PGC) in radiotherapy services. The establishment of the National Quality Audit Program (PNAC) is a superior stage. The National Control Center for Medical Devices, as the national regulator entity for the control and supervision of medical devices in the National Health System, is responsible for the making and execution of the PNAC. The audit modality selected was the inspection visit in situ due to its intrinsic advantages, our geographical extension and the number of radiotherapy services. This paper presents the methodology for the execution of the PNAC, in form of a Normalized Procedure of Operation (PNO) that defines the objectives, scope, terms and definitions, responsibilities, composition and selection of the auditor team, security's conditions, materials and equipment, steps of the audit execution, results calculation and interpretation, records, etc. (author)

  1. Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom.

    Science.gov (United States)

    Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

    2014-07-01

    To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques.

  2. A high-quality factor of 267 000 micromechanical silicon resonator utilizing TED-free torsional vibration mode

    Science.gov (United States)

    Nakamura, K.; Naito, Y.; Onishi, K.; Kawakatsu, H.

    2012-12-01

    In industrial applications of a micromechanical silicon resonator as a physical sensor, a high-quality factor Q and a low-temperature coefficient of Q (TCQ) are required for high sensitivity in a wide temperature range. Although the newly developed thin film encapsulation technique enables a beam to operate with low viscous damping in a vacuum cavity, the Q of a flexural vibration mode is limited by thermo-elastic damping (TED). We proposed a torsional beam resonator which features both a high Q and a low TCQ because theoretically the torsional vibration mode does not suffer from TED. From experiments, Q of 267 000 and TCQ of 1.4 for the 20 MHz torsional vibration mode were observed which were superior to those of the flexural mode. The pressure of the residual gas in the cavity of only 20 pl volume, which is one of the energy loss factors limiting the Q, was successfully estimated to be 1-14 Pa. Finally, the possibilities of improving the Q and the difference of the measured TCQ from a theoretical value were discussed.

  3. Analysis Supporting Factors and Constraints LPMP Performance in Improving the Quality of Education in Jambi Province

    Science.gov (United States)

    Rosadi, Kemas Imron

    2015-01-01

    Development of education in Indonesia is based on three aspects, namely equity and expansion, quality and relevance, as well as good governance. Quality education is influenced by several factors related to quality education managerial leaders, limited funds, facilities, educational facilities, media, learning resources, tools and training…

  4. SU-F-T-429: Craniospinal Irradiation by VMAT Technique: Impact of FFF Beam and High Resolution MLC On Plan Quality

    Energy Technology Data Exchange (ETDEWEB)

    Ganesh, T; Sarkar, B; Munshi, A; Mohanti, B [Fortis Memorial Research Institute, Gurgaon, Haryana (India)

    2016-06-15

    Purpose: Objective of this study was to evaluate the impact of using flattening filter free (FFF) beam with 0.5 cm multileaf collimator (MLC) leaves over conventional flattened beam with 1 cm leaf width MLC on the treatment plan quality in cranio-spinal irradiation (CSI). Methods: For five medulloblastoma cases (3 males and 2 females), who were previously treated by volumetric modulated arc therapy (VMAT) technique using conventional flattened beam shaped by 1 cm width MLC leaves, four test plans were generated and compared against the delivered plan. These retrospective plans consisted of four different combinations of flattened and FFF beams from Elekta’s Agility treatment head with 0.5 cm width MLC leaves. Sparing of organs at risks (OAR) in terms of dose to 5%, 50%, 75% and 90% volumes, mean and maximum dose were evaluated. Results: All plans satisfied the planning objective of covering 95% of PTV by at least 95% of prescription dose. Marginal variation of dose spillage was observed between different VMAT plans at very low dose range (1–5 Gy). Variation in dose statistics for PTVs and OARs were within 1% or 1 Gy. Amongst the five plans, the plan with flattened beam with 1 cm MLC had the highest number of MUs, 2.13 times higher than the plan with Agility MLC with FFF beam that had the least number of MUs. No statistically significant difference (p≥0.05) was observed between the reference plan and the retrospectively generated plans in terms of PTV coverage, cold spot, hot spot and organ at risk doses. Conclusion: In the treatment of CSI cases by VMAT technique, FFF beams and/or finer width MLC did not exhibit advantage over the flattened beams or wider MLC in terms of plan quality except for reduction in MUs.

  5. Quality factors quantification/assurance for software related to safety in nuclear power plants

    International Nuclear Information System (INIS)

    Nunez McLeod, J.E.; Rivera, S.S.

    1997-01-01

    Quality assurance plan is needed to guarantee the software quality. The use of such a plan involves activities that should take place all along the life cycle, and which can be evaluated using the so called quality factors. This is due to the fact that the quality itself cannot be measured, but some of its manifestations can be used for this purpose. In the present work, a methodology to quantify a set of quality factors is proposed, for software based systems to be used in safety related areas in nuclear power plants. (author) [es

  6. Quality of life and cost factors in panic disorder.

    Science.gov (United States)

    Davidson, J R

    1996-01-01

    Quality of life encompasses domains of personal happiness, role fulfillment, and health status. Increasing attention has been paid to the relationship between quality of life and panic disorder, with accumulating evidence now available to suggest impairment in several domains among subjects with panic disorder. This review summarizes the results of community-based and treatment-seeking populations of subjects with panic disorder. Impaired personal happiness, restricted role functioning, and increased use of health services are all described. Evidence suggests that accurate diagnosis and effective treatment can significantly lessen health service utilization, resulting in substantial cost offset and also leading to increased work productivity and personal effectiveness.

  7. Quality factor due to roughness scattering of shear horizontal surface acoustic waves in nanoresonators

    NARCIS (Netherlands)

    Palasantzas, G.

    2008-01-01

    In this work we study the quality factor associated with dissipation due to scattering of shear horizontal surface acoustic waves by random self-affine roughness. It is shown that the quality factor is strongly influenced by both the surface roughness exponent H and the roughness amplitude w to

  8. Comparison of coronary artery calcium screening image quality between C-150 and e-Speed electron beam scanners.

    Science.gov (United States)

    Budoff, Matthew J; Shinbane, Jerold S; Oudiz, Ronald J; Child, Janis; Carson, Sivi; Chau, Alex; Tseng, Philip; Gao, Yanlin; Mao, Songshou

    2005-03-01

    The newest generation of electron beam tomographic scanner (e-Speed) has increased spatial and temporal resolution compared with the C-150 XP scanner. The aim of this study was to evaluate coronary artery calcium screening image quality between the e-Speed and C-150 scanners (GE Imatron, San Francisco, CA). Studies from 41 patients (14 women and 27 men) who underwent serial coronary artery calcium screening with the C-150 (first study) and the e-Speed (second study) were analyzed. Individual computed tomography (CT) slices were assessed for coronary artery motion artifacts, and CT Hounsfield units (HU) and noise values (CT HU standard deviation) at 16 discrete cardiac sites were measured and averaged. With the e-Speed scanner, there were significant decreases in right coronary artery motion artifacts compared with the C-150 scanner (0.3% versus 1.8%, P Image quality is significantly improved with use of the e-Speed scanner, due to its improved temporal and spatial resolution, compared with the C-150 scanner.

  9. Image quality and absorbed dose comparison of single- and dual-source cone-beam computed tomography.

    Science.gov (United States)

    Miura, Hideharu; Ozawa, Shuichi; Okazue, Toshiya; Kawakubo, Atsushi; Yamada, Kiyoshi; Nagata, Yasushi

    2018-04-17

    Dual-source cone-beam computed tomography (DCBCT) is currently available in the Vero4DRT image-guided radiotherapy system. We evaluated the image quality and absorbed dose for DCBCT and compared the values with those for single-source CBCT (SCBCT). Image uniformity, Hounsfield unit (HU) linearity, image contrast, and spatial resolution were evaluated using a Catphan phantom. The rotation angle for acquiring SCBCT and DCBCT images is 215° and 115°, respectively. The image uniformity was calculated using measurements obtained at the center and four peripheral positions. The HUs of seven materials inserted into the phantom were measured to evaluate HU linearity and image contrast. The Catphan phantom was scanned with a conventional CT scanner to measure the reference HU for each material. The spatial resolution was calculated using high-resolution pattern modules. Image quality was analyzed using ImageJ software ver. 1.49. The absorbed dose was measured using a 0.6-cm 3 ionization chamber with a 16-cm-diameter cylindrical phantom, at the center and four peripheral positions of the phantom, and calculated using weighted cone-beam CT dose index (CBCTDI w ). Compared with that of SCBCT, the image uniformity of DCBCT was slightly reduced. A strong linear correlation existed between the measured HU for DCBCT and the reference HU, although the linear regression slope was different from that of the reference HU. DCBCT had poorer image contrast than did SCBCT, particularly with a high-contrast material. There was no significant difference between the spatial resolutions of SCBCT and DCBCT. The absorbed dose for DCBCT was higher than that for SCBCT, because in DCBCT, the two x-ray projections overlap between 45° and 70°. We found that the image quality was poorer and the absorbed dose was higher for DCBCT than for SCBCT in the Vero4DRT. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of

  10. Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality

    Science.gov (United States)

    Helge Østerås, Bjørn; Skaane, Per; Gullien, Randi; Catrine Trægde Martinsen, Anne

    2018-02-01

    The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra™). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra™. AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.

  11. Factors Influencing Assessment Quality in Higher Vocational Education

    Science.gov (United States)

    Baartman, Liesbeth; Gulikers, Judith; Dijkstra, Asha

    2013-01-01

    The development of assessments that are fit to assess professional competence in higher vocational education requires a reconsideration of assessment methods, quality criteria and (self)evaluation. This article examines the self-evaluations of nine courses of a large higher vocational education institute. Per course, 4-11 teachers and 3-10…

  12. Factors impacting on the microbiological quality and safety of ...

    African Journals Online (AJOL)

    hope&shola

    2010-12-06

    Dec 6, 2010 ... in the distribution system for the treated sea-water used during processing. Although, sea-water could be an alternative source of water for marine fish processing plants, the treatment and the quality of the .... Small grey round.

  13. Factors associated with low quality of life in schizophrenia

    Directory of Open Access Journals (Sweden)

    Cardoso Clareci Silva

    2005-01-01

    Full Text Available Interest in quality of life in mental health care has been stimulated by the deinstitutionalization of psychiatric patients as well as a parallel interest in understanding the scope of their daily lives. This study aims to investigate the socio-demographic and clinical variables related to low quality of life, using a cross-sectional design to evaluate quality of life by means of the QLS-BR scale. We interviewed a sample of 123 outpatients from a reference mental health center in Divinópolis, Minas Gerais State, Brazil, clinically diagnosed with schizophrenia. Univariate and multivariate logistic regression analyses were carried out. The results showed that low quality of life is associated with one or more of the following: male gender, single marital status, low income plus low schooling, use of three or more prescribed psychoactive drugs, psychomotor agitation during the interview, and current follow-up care. The study identifies plausible indicators for the attention and care needed to improve psychiatric patient treatment.

  14. Quality management in schools: Analysis of mediating factors

    African Journals Online (AJOL)

    South African Journal of Education, Volume 38, Number 2, May 2018. 1 ... the greater the perception of quality among the teaching staff, regardless of the model used. This leads to the .... Hypothesis 1: Given its higher profile in the education ...

  15. Do Non-Economic Quality of Life Factors Drive Immigration?

    Science.gov (United States)

    Pacheco, Gail Anne; Rossouw, Stephanie; Lewer, Joshua

    2013-01-01

    This paper contributes to the immigration literature by generating two unique non-economic quality of life (QOL) indices and testing their role on recent migration patterns. Applying the generated QOL indices in conjunction with four independent welfare measures to an augmented gravity model of immigration, this paper finds an insignificant…

  16. Investigation of factors affecting the quality of americium electroplating.

    Science.gov (United States)

    Trdin, M; Benedik, L; Samardžija, Z; Pihlar, B

    2012-09-01

    Four different electrolyte solutions were used in the electrodeposition of americium and their influences on the quality of the thin layer of deposited americium isotopes in combination with three different cathode disc materials were investigated. The relations between alpha spectral resolution and disc surface properties were established. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. EVALUATION OF QUALITY CATERING SERVICES AS A FACTOR

    Directory of Open Access Journals (Sweden)

    Ewa Cieślik

    2014-09-01

    Full Text Available The aim of this study was to assess the impact of quality catering services on the increase of consumers’ confidence. The survey data were collected among 200 inhabitants of the district town of the province of Silesia taking into account their gender, age and occupational status. The research tool was the authoring questionnaire. The scope of the research included the quality of catering services, including customer service, and the level of customer satisfaction and know why the use of catering services. The results indicate a close correlation between the quality of catering services (cleanliness of premises, interior design, appearance / hygiene service staff and customers’ satisfaction. The majority of the respondents seldom use the food service and catering establishments; they choose affordable business premises, mostly fast food. Then, their attention is paid to their own tastes and prices, of the offered dishes. For the polled a very important criterion for choosing a place is the service staff of the establishment (manners, hygiene, appearance. The quality of catering services is very important for the customers, as it determines the choice of the catering facility and increases consumers’ loyalty in the institution.

  18. Deep inspiration breath-hold radiotherapy for lung cancer: impact on image quality and registration uncertainty in cone beam CT image guidance

    DEFF Research Database (Denmark)

    Josipovic, Mirjana; Persson, Gitte F; Bangsgaard, Jen