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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 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...,13]. In this work we have adopted the sensible approach of choosing the principal axes Fig. 1. (Color online) Added far-field divergence due to the aperture size as a result of truncation. 1374 J. Opt. Soc. Am. A / Vol. 28, No. 7 / July 2011 C. Mafusire and A...

  2. 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

  3. Fitting relationship between the beam quality β factor of high-energy laser and the wavefront aberration of laser beam

    Science.gov (United States)

    Ji, Zhong-Ye; Zhang, Xiao-Fang

    2018-01-01

    The mathematical relation between the beam quality β factor of high-energy laser and the wavefront aberration of laser beam is important in beam quality control theory of the high-energy laser weapon system. In order to obtain this mathematical relation, numerical simulation is used in the research. Firstly, the Zernike representations of typically distorted atmospheric wavefront aberrations caused by the Kolmogoroff turbulence are generated. And then, the corresponding beam quality β factors of the different distorted wavefronts are calculated numerically through fast Fourier transform. Thus, the statistical distribution rule between the beam quality β factors of high-energy laser and the wavefront aberrations of the beam can be established by the calculated results. Finally, curve fitting method is chosen to establish the mathematical fitting relationship of these two parameters. And the result of the curve fitting shows that there is a quadratic curve relation between the beam quality β factor of high-energy laser and the wavefront aberration of laser beam. And in this paper, 3 fitting curves, in which the wavefront aberrations are consisted of Zernike Polynomials of 20, 36, 60 orders individually, are established to express the relationship between the beam quality β factor and atmospheric wavefront aberrations with different spatial frequency.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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)

  9. 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

  10. 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

  11. Cone-beam CT hepatic arteriography in chemoembolization for hepatocellular carcinoma: angiographic image quality and its determining factors.

    Science.gov (United States)

    Lee, In Joon; Chung, Jin Wook; Yin, Yong Hu; Kim, Hyo-Cheol; Kim, Young Il; Jae, Hwan Jun; Park, Jae Hyung

    2014-09-01

    To analyze image quality and the factors that determine it for cone-beam computed tomography (CT) hepatic arteriography in chemoembolization for hepatocellular carcinoma (HCC). From September 2009-December 2010, 399 consecutive patients referred for chemoembolization of HCC were scheduled for cone-beam CT scan. There were 12 patients (3%) excluded because of difficulty with breath-hold. Of the 387 patients who underwent cone-beam CT hepatic arteriography, 100 patients were ultimately included in the study according to inclusion criteria. Maximum intensity projection images were scored for image quality of each segmental hepatic artery. Potential determining factors for image quality were diaphragmatic motion, portal vein enhancement, and hepatic artery-to-parenchyma enhancement ratio. The flow rate of contrast media, x-ray delay, and location of the catheter tip were also evaluated. It was possible to trace at least subsegmental hepatic arteries in 625 of 700 segments (89.3%) on cone-beam CT hepatic arteriography. Diaphragmatic motion, prominent portal vein enhancement, and low hepatic artery-to-parenchyma enhancement ratio worsened image quality (P cone-beam CT hepatic arteriography images was good enough to trace subsegmental hepatic arteries at a minimum. Respiratory and cardiac motion, portal vein enhancement, and hepatic artery-to-parenchyma enhancement ratio significantly affected the image quality of cone-beam CT hepatic arteriography. Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.

  12. 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)

  13. Simulation and experiment studies of aberration effects on the measurement of laser beam quality factor (M2)

    Science.gov (United States)

    Meng, Lingqiang; Huang, Zheqiang; Han, Zhigang; Shen, Hua; Zhu, Rihong

    2018-01-01

    In the measurement system of beam quality factor, M2, wave-front and intensity aberrations caused by optical elements, thermal effects, residual pump light, etc., influence the measurement results. The influence was analyzed using the angular spectrum and the finite element methods. Simulation of the impact of different aberrations, thermal effects and residual pump light on the measurement of the M2 is provided. The M2 of a high-power fiber laser is measured by a beam quality analyzer when the laser transmits through a high absorption red glass with different output power. The results from the experiment and the simulation have good consistency. The simulation and experiment results can be applied for the designs of high-power laser, laser beam quality measurement, and laser-launching systems.

  14. 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)

  15. Measurements of kQ beam quality correction factors for the NE2611A chamber in high-energy photon beams using the NMi water calorimeter

    International Nuclear Information System (INIS)

    Pieksma, M.; Prez, L.A. de; Dijk, E. van; Aalbers, A.H.L.

    2002-01-01

    Full text: Recently published protocols for clinical reference dosimetry in external high-energy photon and electron beam radiotherapy by the AAPM and the IAEA are no longer based on traditional air-kerma standards, but have instead adopted absorbed dose to water as the key quantity. The most direct way to determine the absorbed dose to water is by employing a sealed-water type calorimeter. A number of national standards laboratories, among which the NMi, are presently conducting effort towards developing water calorimeters as the new standard for absorbed dose to water. The design of the NMi water calorimeter has several unique features. It is portable and compact, has radiation windows for both vertical and horizontal beams, and has a built-in waterproof ionization chamber, which can be used to determine experimental correction factors for the calorimeter lid, walls, etc. Thermistor probes operable at 4 deg. C are mounted in a sealed high-purity water cell. A high-quality water purifying system has been installed and integrated into a filling station for the water cell, including a bubbling stage to saturate the water with different gasses to control the well-known heat defect. A forthcoming revision of the NCS (Netherlands Commission on Radiation Dosimetry) protocols for dosimetry of high-energy photon and electron beams has direct relevance for the NMi water calorimeter. In accordance with the new AAPM and IAEA protocols, these revised protocols will also no longer be based on air kerma, but on absorbed dose to water instead. The NCS subcommittee 'Uniformity Dosimetry Protocols' is currently drafting new Codes of Practice for determining the absorbed dose to water for high-energy photon and electron beams used in radiotherapy institutes in the Netherlands and Belgium. Part of the new protocols will be a table of experimentally determined k Q beam quality correction factors for photon beam qualities and dosimetric equipment (graphite ionization chambers and

  16. Comparison of the absorbed dose at calibration depth of photon beams using the Japan society of medical physics 12 beam quality conversion factor in the presence or absence of a waterproofing sleeve

    International Nuclear Information System (INIS)

    Kinoshita, Naoki; Kita, Akinobu; Murai, Emi; Nishimoto, Yasuhiro; Toi, Akiko; Shimada, Masato; Sasamoto, Kouhei; Adachi, Toshiki; Takemura, Akihiro

    2013-01-01

    In standard external beam radiotherapy dosimetry, which is based on absorbed dose by water, the absorbed dose at any calibration depth is calculated using the same beam quality conversion factor, regardless of the presence or absence of a waterproofing sleeve. In this study, we evaluated whether there were differences between absorbed doses at calibration depths calculated using a beam quality conversion factor including a wall correction factor that corresponds to a waterproofing sleeve thickness of 0.3 mm, and without a waterproofing sleeve. The Japan Society of Medical Physics (JSMP) has reported that the uncertainty of the results using a beam quality conversion factor that included a wall correction factor corresponding to a waterproofing sleeve thickness of 0.3 mm, regardless of the presence or absence of the sleeve, was 0.2%. This uncertainty proved to be in agreement with the reported range.(author)

  17. 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.

  18. On the behavior of fc,Q factors with quality indexes for medium energy X-ray beams: A Monte Carlo study with PENELOPE

    Science.gov (United States)

    Chica, U.; Anguiano, M.; Lallena, A. M.

    2013-09-01

    A series of Monte Carlo simulations has been performed to determine the behavior of the factor fc,Q as a function of the usual quality indexes for medium energy X-ray beams. Up to 46 beams, with spectra generated with the codes XCOMP5R and SPEKCALC, for potentials up to 300 kV, were transported using the Monte Carlo code PENELOPE to calculate the doses in water and in a PTW 30001 ionization chamber, both at the reference depth. The half-value layer (the usual quality index for these beams) and other two quality indexes, the generating potential and the homogeneity coefficient, have been considered. The calculated fc,Q factors are well described with a function that involves the power of the half-value layer up to the square and a second quality index linearly. The predictive power of this combination has been studied.

  19. 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 ...

  20. 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.

  1. 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.

  2. Evaluation of beam quality for high-power lasers

    Science.gov (United States)

    Yang, Hongru; Wu, Lei; Wang, Xuexin; Shi, Jifang; Li, Gaoping; Ji, Xiao

    2008-03-01

    High-power lasers are widely used in various scientific, industrial and military applications. There is currently a desire for precision measurement the beam quality of high-power lasers in order to evaluate the performance of the laser systems and the operational effectiveness of chemical and solid-state high-power laser weapons. There are many methods of beam quality determination, such as beam parameter product, encircled energy ratio BQ, Strehi ratio, diffraction limit factor β and beam propagation factor M2. In this paper, a beam quality measurement device is developed for high-power lasers. This device consists of a beam attenuator with large reflective ratio and minimal wavefront distortion, an off-axis parabolic mirror, an imaging lens and an infrared focal plane array detector. The laser beam intensity distribution, beam width, beam divergence and beam pointing stability can be obtained in real-time and the beam quality can be evaluated by the various determinations through imaging process. Advantages and disadvantages of these beam quality determination for evaluation the performance of the high-power lasers are analyzed and discussed. The measurement uncertainties of relative parameters are also analyzed and discussed.

  3. Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT devices

    Directory of Open Access Journals (Sweden)

    Ninita Lindfors

    Full Text Available Objectives: The aim of this in vitro study was to evaluate how a deviation from the horizontal plane, affects the image quality in two different CBCT-devices. Methods: A phantom head SK150 (RANDO, The Phantom Laboratory, Salem, NY, USA was examined in two CBCT-units: Accuitomo 80 and Veraviewepocs 3D R100 (J. Morita Mfg. Corp. Kyoto, Japan. The phantom head was placed with the hard palate parallel to the horizontal plane and tilted 20 ° backwards. Exposures were performed with different field of views (FOVs, voxel sizes, slice thicknesses and exposure settings. Effective dose was calculated using PCXMC 2.0 (STUK, Helsinki, Finland. Image quality was assessed using contrast-to-noise-ratio (CNR. Region of interest (ROI was set at three different levels of the mandibular bone and soft tissue, uni- and bilaterally in small and large FOVs, respectively. CNR values were calculated by CT-value and standard deviation for each ROI. Factor analysis was used to analyze the material. Results: Tilting the phantom head backwards rendered significantly higher mean CNR values regardless of FOV. The effective dose was lower in small than in large FOVs and varied to a larger extent between CBCT-devices in large FOVs. Conclusions: Head position can affect the image quality. Tilting the head backward improved image quality in the mandibular region. However, if influenced by other variables e.g. motion artifacts in a clinical situation, remains to be further investigated. Advances in knowledge: Image quality assessed using CNR values to investigate the influence of different patient positions and FOVs. Keywords: Image quality, CBCT, Radiation dose, Patient position, FOV

  4. 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.

  5. 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%.

  6. 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

    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.......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...

  7. 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)

  8. 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...

  9. 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...

  10. 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.

  11. 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

  12. 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.

  13. 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)

  14. 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)

  15. 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

  16. 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)

  17. 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)

  18. 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.

  19. 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

  20. Propagation of low-quality laser beams in turbulent air: new fast simulation methods and experimental results

    Science.gov (United States)

    Hall, Thomas; Spindler, Gerhard; Becker, Peter; Grünewald, Karin; Pargmann, Carsten; Duschek, Frank

    2017-11-01

    Novel inherently fast methods basing upon fundamental Gaussian modes are presented to numerically simulate the propagation behavior of a low-quality laser beam, i.e., a beam characterized by a high quality factor M^2, in turbulent air. Actually, for a given initial diameter, beam wandering and spread at the target position is calculated. Test results are checked against respective simulations using higher-order mode beams having clearly defined quality factors and nearly perfect agreement is demonstrated. Experiments performed on the German Aerospace Center (DLR) laser test range at Lampoldshausen near Stuttgart satisfactorily accord with the predictions of the proposed simulation techniques.

  1. Generation of High Quality Laser Accelerated Ion Beams

    OpenAIRE

    Esirkepov, T. Zh.; Bulanov, S. V.; Nishihara, K.; Tajima, T.; Pegoraro, F.; Khoroshkov, V. S.; Mima, K.; Daido, H.; Kato, Y.; Kitagawa, Y.; Nagai, K.; Sakabe, S.

    2002-01-01

    In order to achieve a high quality, i. e. monoergetic, intense ion beam, we propose the use of a double layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The high quality proton beams from the double layer target, irradiated by an ultra-intense laser pulse, are demonstrated with three dimensional Particle-in-Cell simulations.

  2. 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....... The applicability of the International Standards Organization 11146 : 1999 standard for$M^2$measurement of the beam quality of HC-PCFs is discussed. Because they are dependent on the measurement parameters, such as choice of aperturing scheme and the axis of measurement,$M^2$values could vary from 1.32 to 3.......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....

  3. Factors Influencing Healthcare Service Quality

    OpenAIRE

    Ali Mohammad Mosadeghrad

    2014-01-01

    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 o...

  4. 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.

  5. Cherenkov detector for beam quality measurement

    Science.gov (United States)

    Orfanelli, S.; CMS Collaboration

    2016-07-01

    A new detector to measure the machine induced background at larger radii has been developed and installed in the CMS experiment at the LHC. It consists of forty modules, each comprising a quartz bar read out by a photomultiplier tube. Since Cherenkov radiation is emitted in a forward cone around the charged particle trajectory, these detectors can distinguish between the arrival directions of the machine induced background and the collision products. The back-end electronics consists of a uTCA readout with excellent time resolution. The installation in the CMS is described and first commissioning measurements with the LHC beams in Run II are presented.

  6. Sidewall quality in proton beam writing

    International Nuclear Information System (INIS)

    Chiam, S.Y.; Kan, J.A. van; Osipowicz, T.; Udalagama, C.N.B.; Watt, F.

    2007-01-01

    Proton beam writing has been shown to allow the fabrication of high aspect ratio nanostructures at sub-100 nm dimension and with smooth and vertical sidewalls. For applications such as the fabrication of waveguides, sidewall smoothness is an important issue. We report results from investigations into side wall roughness measured directly with Atomic Force Microscopy. Structures were written in bulk poly(methylmethacrylate) (PMMA) with 2 MeV protons specifically to allow side access. We studied the effects of different scanning algorithms and also the variation of wall roughness with development time and ion penetration depth. Our results indicate that sidewall rms roughness of less than 7 nm is readily achievable. Multi-loop scanning and optimization of the scanning algorithm can lead to significant improvements in sidewall smoothness

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.)

  13. 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.

  14. Quality factor of aberrated gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2010-09-01

    Full Text Available Optics research team! Opportunities: MSc and PhD studentships, Post docs and Sabbaticals Contact: Prof Andrew Forbes or Dr Stef Roux www.csir.co.za/lasers/index_mathematical_optics.html ...

  15. 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.

  16. 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.

  17. Beam quality evaluation of 20/400 µm large-mode-area fiber based on mode decomposition and reconstruction

    Science.gov (United States)

    Bai, Gang; Chen, Xiaolong; Yang, Yifeng; Zheng, Ye; Zhao, Xiang; Liu, Kai; Zhao, Chun; Qi, Yunfeng; He, Bing; Zhou, Jun

    2018-02-01

    We implement a fast beam quality factor evaluation of a large-mode-area 20/400 µm fiber based on mode decomposition and reconstruction. Each transverse mode power weight factor and relative phase difference at the fiber output facet are estimated by the stochastic parallel gradient descent algorithm based simply on the instantaneous acquired charge coupled device near-field beam profile. The beam quality factor M 2 in two orthogonal directions can be analyzed in consideration of the complex amplitude of each transmission mode. The performance of our method is verified by applying it to the beam quality measurement of a 217.4 W high-power fiber laser. The calculated M 2 in two directions are 1.25 and 1.18, respectively, which is in good agreement with the measured results of 1.29 and 1.24. The proposed method could be helpful for beam quality evaluation of high-power fiber lasers and amplifiers, where the rapid change of the beam quality factor is difficult to detect due to mode instability.

  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. 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

  20. Beam propagation factors and kurtosis parameters of a Lorentz-Gauss vortex beam.

    Science.gov (United States)

    Zhou, Guoquan

    2014-06-01

    Based on the second-order and the higher-order moments, analytical expressions for the beam propagation factors of a Lorentz-Gauss vortex beam with l=1 have been derived, and analytical propagation expressions for the kurtosis parameters of a Lorentz-Gauss vortex beam with l=1 through a paraxial and real ABCD optical system have also been presented. The M² factor is determined by the parameters a and b and decreases with increasing the parameter a or b. The M² factor is validated to be larger than 2. The kurtosis parameters depend on the diffraction-free ranges of the Lorentz part, the parameters a and b, and the ratio A/B. The kurtosis parameters of a Lorentz-Gauss vortex beam propagating in free space are demonstrated in different reference planes. In the far field, the kurtosis parameter K decreases with increasing one of the parameters a and b. Upon propagation, the kurtosis parameter K first decreases, then increases, and finally tends to a saturated value. In any case, the kurtosis parameter K is larger than 2. This research is beneficial to optical trapping, guiding, and manipulation of microscopic particles and atoms using Lorentz-Gauss vortex beams.

  1. 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

  2. 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)

  3. 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%.

  4. 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

  5. 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%

  6. 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.

  7. A Review on Audit Quality Factors

    OpenAIRE

    Seyed Mahmoud Hosseinniakani; Helena Inacio; Rui Mota

    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...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. A simple method for boosting the beam quality of commercial DPL

    Science.gov (United States)

    Zhang, Guang-Yin; Jiao, Zhi-Yong; Yan, Cai-Fan; Ding, Xin; Zhang, Chao-Bo; Zhang, Xiao-Hua; Gu, Xue-Wen; Song, Feng

    2003-12-01

    A simple method for boosting the beam quality of a commercial laser diode pumped laser (DPL) is put forward. By keeping one of the mirrors unchanged and the moving the other mirror a proper distance away from the laser rod, high beam quality laser output is realized.

  14. 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

  15. 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.

  16. 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.

  17. Can Neutron Beam Components and Radiographic Image Quality be determined by the Use of Beam Purity and Sensitivity Indicators?

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1986-01-01

    radiography f a c i l i t i e s of the European Community. The direct, transfer and track-etch methods using different f i lm recording materials were used. Neutron beam components were calculated from film density measurements under the beam purity indicators and radiographic image quality was assessed......In the Euratom Neutron Radiography Working Group Test Program beam purity and s e n s i t i v i t y indicators, as prescribed by the ASTM E 545-81 were used together with the NRWG beam purity i n d i c a t o r - f u e l and c a l i b r a t i o n fuel pin. They were radiographed together at neutron...

  18. Characterization and evaluation of an integrated quality monitoring system for online quality assurance of external beam radiation therapy.

    Science.gov (United States)

    Hoffman, David; Chung, Eunah; Hess, Clayton; Stern, Robin; Benedict, Stanley

    2017-01-01

    The aim of this work was to comprehensively evaluate a new large field ion chamber transmission detector, Integral Quality Monitor (IQM), for online external photon beam verification and quality assurance. The device is designed to be mounted on the linac accessory tray to measure and verify photon energy, field shape, gantry position, and fluence before and during patient treatment. Our institution evaluated the newly developed ion chamber's effect on photon beam fluence, response to dose, detection of photon fluence modification, and the accuracy of the integrated barometer, thermometer, and inclinometer. The detection of photon fluence modifications was performed by measuring 6 MV with fields of 10 cm × 10 cm and 1 cm × 1 cm "correct" beam, and then altering the beam modifiers to simulate minor and major delivery deviations. The type and magnitude of the deviations selected for evaluation were based on the specifications for photon output and MLC position reported in AAPM Task Group Report 142. Additionally, the change in ion chamber signal caused by a simulated IMRT delivery error is evaluated. The device attenuated 6 MV, 10 MV, and 15 MV photon beams by 5.43 ± 0.02%, 4.60 ± 0.02%, and 4.21 ± 0.03%, respectively. Photon beam profiles were altered with the IQM by < 1.5% in the nonpenumbra regions of the beams. The photon beam profile for a 1 cm × 1 cm 2 fields were unchanged by the presence of the device. The large area ion chamber measurements were reproducible on the same day with a 0.14% standard deviation and stable over 4 weeks with a 0.47% SD. The ion chamber's dose-response was linear (R 2 = 0.99999). The integrated thermometer agreed to a calibrated thermometer to within 1.0 ± 0.7°C. The integrated barometer agreed to a mercury barometer to within 2.3 ± 0.4 mmHg. The integrated inclinometer gantry angle measurement agreed with the spirit level at 0 and 180 degrees within 0.03 ± 0.01 degrees and 0.27 ± 0.03 at 90 and 270 degrees. For the

  19. 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.

  20. The stress intensity factor for the double cantilever beam

    Science.gov (United States)

    Fichter, W. B.

    1983-01-01

    Fourier transforms and the Wiener-Hopf technique are used in conjunction with plane elastostatics to examine the singular crack tip stress field in the double cantilever beam (DCB) specimen. In place of the Dirac delta function, a family of functions which duplicates the important features of the concentrated forces without introducing unmanageable mathematical complexities is used as a loading function. With terms of order h-squared/a-squared retained in the series expansion, the dimensionless stress intensity factor is found to be K (h to the 1/2)/P = 12 to the 1/2 (a/h + 0.6728 + 0.0377 h-squared/a-squared), in which P is the magnitude of the concentrated forces per unit thickness, a is the distance from the crack tip to the points of load application, and h is the height of each cantilever beam. The result is similar to that obtained by Gross and Srawley by fitting a line to discrete results from their boundary collocation analysis.

  1. Environmental factors and semen quality

    DEFF Research Database (Denmark)

    Jurewicz, Joanna; Hanke, Wojciech; Radwan, Michal

    2009-01-01

    OBJECTIVES: An increasing number of reports suggest that chemical and physical agents in the environment, introduced and spread by human activity, may affect male fertility in humans. This article aims at evaluating the impact of environmental exposures (pesticides, phthalates, PCBs, air pollution...... 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...

  2. Strength and stiffness of small glued-laminated beams with different qualities of tension laminations

    Science.gov (United States)

    Catherine M. Marx; Russell C. Moody

    1981-01-01

    A total of 180 small Douglas Fir–Larch (DF-L) or Southern Pine (SP) glued-laminated beams were evaluated to determine the tension lamination quality necessary to obtain desired design stresses. The test beams had either the regular laminating grades of L1 DF-L/No. 1D SP or the special 302-24 laminating grade as tension laminations. Because an initial set of SP beams...

  3. The Effect of Spandrel Beam's Specification on Response Modification Factor of Concrete Coupled Shear Walls

    OpenAIRE

    Mussa Mahmoudi; seyed Mohammad Reza Mortazavi; Saeid Ajdari

    2016-01-01

    Response modification factor (R factor) is one of the seismic design parameters to be considered in evaluating the performance of buildings during strong motions. This paper has tried to evaluate the response modification factor of concrete coupled shear wall structures with various length/depth ratios of spandrel beams. The effect of diagonal reinforcement of spandrel beam was also evaluated on the R factor. The R factor directly depends on overstrength factor and ductility reduction factor....

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. Surface water quality assessment using factor analysis

    African Journals Online (AJOL)

    2006-01-16

    Jan 16, 2006 ... factors extracted by the Centroid method, rotated by Varimax rotation (Ahmed et al., 2005). Calculated eigenvalues, per cent. Figure 1. Sketch map of water quality monitoring stations in Buyuk. Menderes Basin in Turkey. TABLE 1. Descriptive statistics of water quality data under low-flow conditions. Variable.

  9. 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

  10. 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

  11. 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.

  12. Adaptive slab laser beam quality improvement using a weighted least-squares reconstruction algorithm.

    Science.gov (United States)

    Chen, Shanqiu; Dong, LiZhi; Chen, XiaoJun; Tan, Yi; Liu, Wenjin; Wang, Shuai; Yang, Ping; Xu, Bing; Ye, YuTang

    2016-04-10

    Adaptive optics is an important technology for improving beam quality in solid-state slab lasers. However, there are uncorrectable aberrations in partial areas of the beam. In the criterion of the conventional least-squares reconstruction method, it makes the zones with small aberrations nonsensitive and hinders this zone from being further corrected. In this paper, a weighted least-squares reconstruction method is proposed to improve the relative sensitivity of zones with small aberrations and to further improve beam quality. Relatively small weights are applied to the zones with large residual aberrations. Comparisons of results show that peak intensity in the far field improved from 1242 analog digital units (ADU) to 2248 ADU, and beam quality β improved from 2.5 to 2.0. This indicates the weighted least-squares method has better performance than the least-squares reconstruction method when there are large zonal uncorrectable aberrations in the slab laser system.

  13. Quantitative image quality evaluation for kV cone-beam CT-based IGRT

    International Nuclear Information System (INIS)

    Lim, S Y; Zin, Hafiz M

    2017-01-01

    The objective of this study is to quantitatively evaluate the image quality of a kV cone-beam CT-based IGRT system (Elekta, XVI) using two commercial CT image quality phantoms, Catphan-600 and CIRS-062QA. Both phantoms consist of similar image quality test modules (uniformity, CT linearity and spatial resolution) but each phantom has different diameter and test pattern design. Each test module was imaged separately using an optimised cone-beam CT imaging parameter. The quality metrics of the reconstructed images were analysed using algorithms developed with MatLab. The image uniformity and the spatial resolution measured with Catphan were of 4% and 40% greater respectively, compared to those measured with CIRS phantom. The differences were due to the beam scattering and hardening originated from the CIRS phantom holder. The contrast-to-noise ratio (CNR) values measured with CIRS phantom were at least 2% higher than that of Catphan. The diameter of CIRS phantom is smaller and resulted in lower beam attenuation. The quantitative image quality assessment algorithms developed for both phantoms provided a phantom-specific set of reference values for a cone-beam CT imaging system as recommended by AAPM TG-142. Further investigation will be performed to resolve beam hardening issue arising from the CIRS phantom holder. (paper)

  14. 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....

  15. 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.

  16. The generation of high-quality, intense ion beams by ultra-intense lasers

    CERN Document Server

    Roth, M; Audebert, Patrick; Blazevic, A; Brambrink, E; Cowan, T E; Fuchs, J; Gauthier, J C; Geissel, M; Hegelich, M; Karsch, S; Meyer-Ter-Vehn, J; Ruhl, H; Schlegel, T; Stephens, R B

    2002-01-01

    Intense beams of protons and heavy ions have been observed in ultra-intense laser-solid interaction experiments. Thereby, a considerable fraction of the laser energy is transferred to collimated beams of energetic ions (e.g. up to 50 MeV protons; 100 MeV fluorine), which makes these beams highly interesting for various applications. Experimental results indicate a very short-pulse duration and an excellent beam quality, leading to beam intensities in the TW range. To characterize the beam quality and its dependence on laser parameters and target conditions we performed experiments using the 100 TW laser system at Laboratoire pour l'Utilisation des Lasers Intenses at the Ecole Polytechnique, France, with focused intensities exceeding 10 sup 1 sup 9 W cm sup - sup 2. We found a strong dependence on the target rear surface conditions allowing to tailor the ion beam by an appropriate target design. We also succeeded in the generation of heavy ion beams by suppressing the proton amount at the target surface. We wi...

  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. A Path Model of Psychosocial Factors Influencing Quality, Quality ...

    African Journals Online (AJOL)

    This study adopted the survey research design using an ex-post facto type to investigate path modeling of psychosocial factors influencing quality marital relationship among married individuals in Southwest Nigeria. The target population ... Three research questions were answered using path analysis. The result showed ...

  19. Fish milt quality and major factors influencing the milt quality ...

    African Journals Online (AJOL)

    In commercial fish production, the evaluation of milt quality is essential in order to increase the efficiency of artificial fertilization. Numerous studies have demonstrated that qualitative parameters of milt (i.e. seminal fluid composition, spermatozoa motility and sperm production) could be influence by several factors including ...

  20. Efficient generation of high beam-quality attosecond pulse with polarization-gating Bessel-Gauss beam from highly-ionized media.

    Science.gov (United States)

    Li, Yang; Zhang, Qingbin; Hong, Weiyi; Wang, Shaoyi; Wang, Zhe; Lu, Peixiang

    2012-07-02

    Single attosecond pulse generation with polarization gating Bessel-Gauss beam in relatively strongly-ionized media is investigated. The results show that Bessel-Gauss beam has the ability to suppress the spatial plasma dispersion effects caused by high density of free electrons, thus the laser field can maintain its spatial profile through highly-ionized medium. This indicates the use of Bessel-Gauss beam has advantages over Gaussian beam in high harmonic generation under high ionization conditions. In our scheme, significant improvement of spatiotemporal properties of harmonics is achieved and an isolated attosecond pulse with high beam quality is filtered out using polarization gating.

  1. 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)

  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. 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

  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. 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.

  7. 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,…

  8. 7 CFR 52.782 - Allowances for quality factors.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Allowances for quality factors. 52.782 Section 52.782... for Quality Factors § 52.782 Allowances for quality factors. Table IV—Allowances for Quality Factors Factor Sample unit size Maximum number permissible for the respective grade A A B B C C Pits 20 ozs Not...

  9. 7 CFR 52.810 - Allowances for quality factors.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Allowances for quality factors. 52.810 Section 52.810... for Quality Factors § 52.810 Allowances for quality factors. Table I—Allowances for Quality Factors Factor Sample unit size Maximum number permissible for the respective grade A B C Color: Vary markedly or...

  10. 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...... gender and smoking were associated with reduced QOL, suggesting that these factors play an independent role on lowering QOL. Depression did not inflate the relationship between asthma severity and worse QOL, suggesting that asthma severity plays an independent role on everyday life regardless...

  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. 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

  14. Machine Protection and Beam Quality during the LHC Injection Process

    CERN Document Server

    Verena Kain, V K

    2005-01-01

    This thesis is concerned with the machine protection system for the LHC injection process, where the intensity of the injected beam is alreay more than one order of magnitude above the equipment damage level. It focuses on a detailed specification, description and performance validation of the protection systems for the transfer from the SPS and the injection into the LHC. Numerical simulations were used to design active (equipment monitoring to ensure correct settings) and passive (collimators and absorbers) protection systems, and to analyze their performance. The simulation methodology was based on two common computer codes: energy deposition simulations were done with FLUKA and particle tracking was done with the tracking module of MAD-X. Realistic machine states were set up for the failure simulations including geometrical and optical mismatch, orbit tolerances, mechanical tolerances, power converter ripples, misalignment of elements and trajectory correction. The equipment damage limit was derived and c...

  15. 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...

  16. 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

    2017-06-01

    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).

  17. 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).

  18. 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)

  19. 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)

  20. Double compression system to increase beam quality in medical linear accelerators

    Science.gov (United States)

    Rajabi, A.; Shokri, B.; Ahmadizadeh, Y.

    2017-06-01

    The modern radiation therapy is now one of the most powerful tools for the treatment of tumors and cancers. During these treatments, the quality of the operation and the clinical requirements are critical. Here in the present work, based on the beam dynamics of the electrons in RF cavities, a new design for enhancing the quality of bunches is proposed. The simulation results show that the new design can increase the quality of the output bunches which consequently increase the quality of the radiotherapy treatment.

  1. Enhancement of image quality with a fast iterative scatter and beam hardening correction method for kV CBCT

    Energy Technology Data Exchange (ETDEWEB)

    Reitz, Irmtraud; Hesse, Bernd-Michael; Nill, Simeon; Tuecking, Thomas; Oelfke, Uwe [DKFZ, Heidelberg (Germany)

    2009-07-01

    The problem of the enormous amount of scattered radiation in kV CBCT (kilo voltage cone beam computer tomography) is addressed. Scatter causes undesirable streak- and cup-artifacts and results in a quantitative inaccuracy of reconstructed CT numbers, so that an accurate dose calculation might be impossible. Image contrast is also significantly reduced. Therefore we checked whether an appropriate implementation of the fast iterative scatter correction algorithm we have developed for MV (mega voltage) CBCT reduces the scatter contribution in a kV CBCT as well. This scatter correction method is based on a superposition of pre-calculated Monte Carlo generated pencil beam scatter kernels. The algorithm requires only a system calibration by measuring homogeneous slab phantoms with known water-equivalent thicknesses. In this study we compare scatter corrected CBCT images of several phantoms to the fan beam CT images acquired with a reduced cone angle (a slice-thickness of 14 mm in the isocenter) at the same system. Additional measurements at a different CBCT system were made (different energy spectrum and phantom-to-detector distance) and a first order approach of a fast beam hardening correction will be introduced. The observed, image quality of the scatter corrected CBCT images is comparable concerning resolution, noise and contrast-to-noise ratio to the images acquired in fan beam geometry. Compared to the CBCT without any corrections the contrast of the contrast-and-resolution phantom with scatter correction and additional beam hardening correction is improved by a factor of about 1.5. The reconstructed attenuation coefficients and the CT numbers of the scatter corrected CBCT images are close to the values of the images acquired in fan beam geometry for the most pronounced tissue types. Only for extreme dense tissue types like cortical bone we see a difference in CT numbers of 5.2%, which can be improved to 4.4% with the additional beam hardening correction. Cupping

  2. 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.

  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. Quality indexes based on water measurements for low and medium energy x-ray beams: A theoretical study with PENELOPE

    Energy Technology Data Exchange (ETDEWEB)

    Chica, U. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada, Spain and FISRAD S.A.S Carrera 64 a No 22-41, Bogotá D.C. (Colombia); Anguiano, M.; Lallena, A. M., E-mail: lallena@ugr.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Vilches, M. [Servicio de Radiofísica, Hospital Universitario “San Cecilio”, Avda. Dr. Olóriz, 16, E-18012 Granada (Spain)

    2014-01-15

    Purpose : To study the use of quality indexes based on ratios of absorbed doses in water at two different depths to characterize x-ray beams of low and medium energies. Methods : A total of 55 x-ray beam spectra were generated with the codes XCOMP5R and SPEKCALC and used as input of a series of Monte Carlo simulations performed with PENELOPE, in which the percentage depth doses in water and thek{sub Q,Q{sub 0}} factors, defined in the TRS-398 protocol, were determined for each beam. Some of these calculations were performed by simulating the ionization chamber PTW 30010. Results : The authors found that the relation betweenk{sub Q,Q{sub 0}} and the ratios of absorbed doses at two depths is almost linear. A set of ratios statistically compatible with that showing the best fit has been determined. Conclusions : The results of this study point out which of these ratios of absorbed doses in water could be used to better characterize x-ray beams of low and medium energies.

  5. Compact, high-power, high-beam-quality quasi-CW microsecond five-pass zigzag slab 1319  nm amplifier.

    Science.gov (United States)

    Guo, Chuan; Zuo, Junwei; Bian, Qi; Xu, Chang; Zong, Qinshuang; Bo, Yong; Shen, Yu; Zong, Nan; Gao, Hongwei; Lin, Yanyong; Yuan, Lei; Liu, Yang; Cui, Dafu; Peng, Qinjun; Xu, Zuyan

    2017-04-20

    We demonstrate a compact, high-power, quasi-continuous-wave (QCW) end-pumped 1319 nm Nd:YAG slab amplifier laser with good beam quality. The laser is based on a QCW pulse Nd:YAG master oscillator and Nd:YAG slab amplifier with multi-pass zigzag architecture. The amplifier operates at a pulse repetition frequency of 500 Hz and pulse width of ∼105  μs, delivering a maximum output power of 51.5 W under absorbed pump power of 217.8 W and corresponding to an extraction efficiency of 14.2%. The beam quality factor is measured to be Mx2=1.61 and My2=1.81 in the orthogonal directions. To the best of our knowledge, this is the first compact, high-power, high-beam-quality QCW Nd:YAG amplifier at 1319 nm based on a multi-pass zigzag slab structure.

  6. 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).

  7. 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).

  8. 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.

  9. An analytical formalism to calculate phantom scatter factors for flattening filter free (FFF) mode photon beams

    International Nuclear Information System (INIS)

    Chung, Heeteak; Prado, Karl L; Yi, Byong Yong

    2014-01-01

    Phantom Scatter Factors, Sp in the Khan formalism (Khan et al 1980 J. Radiat. Oncol. Biol. Phys. 6 745–51) describe medium-induced changes in photon-beam intensity as a function of size of the beam. According to the British Journal of Radiology, Supplement 25, megavoltage phantom scatter factors are invariant as a function of photon-beam energy. However, during the commissioning of an accelerator with flattening filter free (FFF) photon beams (Varian TrueBeam TM  6-MV FFF and 10-MV FFF), differences were noted in phantom scatter between the filtered beams and FFF-mode beams. The purpose of this work was to evaluate this difference and provide an analytical formalism to explain the phantom scatter differences between FFF-mode and the filtered mode. An analytical formalism was devised to demonstrate the source of phantom scatter differences between the filtered and the FFF-mode beams. The reason for the differences in the phantom scatter factors between the filtered and the FFF-mode beams is hypothesized to be the non-uniform beam profiles of the FFF-mode beams. The analytical formalism proposed here is based on this idea, taking the product of the filtered phantom scatter factors and the ratio of the off-axis ratio between the FFF-mode and the filtered beams. All measurements were performed using a Varian TrueBeam TM  linear accelerator with photon energies of 6-MV and 10-MV in both filtered and FFF-modes. For all measurements, a PTW Farmer type chamber and a Scanditronix CC04 cylindrical ionization were used. The in-water measurements were made at depth dose maximum and 100 cm source-to-axis distance. The in-air measurements were done at 100 cm source-to-axis distance with appropriate build-up cap. From these measurements, the phantom scatter factors were derived for the filtered beams and the FFF-mode beams for both energies to be evaluated against the phantoms scatter factors calculated using the proposed algorithm. For 6-MV, the difference between the

  10. 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

  11. 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

  12. 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 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 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 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.

  13. Determination of scatter factor parameters and electron disequilibrium for monoenergetic photon beams.

    Science.gov (United States)

    McDonough, J; Bloch, P; Bjärngard, B E

    1999-02-01

    The tissue-phantom-ratio (TPR) is expressed as the product of the phantom scatter factor (SF), an electron disequilibrium factor, and an attenuation factor, equal to the zero-area TPR. The scatter factor, as a function of depth d and field size s, has been described by two parameters a and w, SF(d,s) = 1 + asd/(ws + d). We have determined the parameters a and w for 20 monoenergetic photon beams between 1 and 20 MeV. Pencil-beam energy-deposition kernels were obtained using Monte Carlo simulations. The kernels were used to calculate broad-beam depth-dose data, which were converted to TPR and fitted to the equation above using an iterative search over a-w space. The parameter a is nearly equal to the attenuation coefficient for all energies while the parameter w increases with energy. The resulting a and w compare favorably to values determined for clinical photon beams, as a function of the measured attenuation coefficient. With the scatter factor determined, we isolated the electron disequilibrium factor for each monoenergetic beam. It can be characterized as a quadratic function of the depth. The coefficients of the quadratic function can be related to the range of the most energetic secondary electron produced.

  14. 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

  15. 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.

  16. Poster - Thur Eve - 41: Effect of beam symmetry on enhanced dynamic wedge quality assurance and tolerance levels.

    Science.gov (United States)

    Meyer, T; Hudson, A

    2012-07-01

    Wedged fields are common in three dimensional conformal radiation therapy and require appropriate quality assurance (QA). Currently, our centre calculates the angle of enhanced dynamic wedge (EDW) deliveries with the PROFILER at a monthly frequency but Canadian guidelines on the recommended QA of enhanced dynamic wedges are not available yet. TG-142 recommendations include monthly validation of the central axis wedge factors with only annual verification of wedge profiles. Our monthly QA results have demonstrated a sensitivity of the calculated EDW angle to open beam symmetry. The goal of this work is to compare wedge angle and direct profile comparison as QA measures of EDW delivery and determine appropriate parameter tolerances. The impact of open field symmetry variations on EDW profiles was determined by varying beam symmetry with a test potentiometer and measuring the resulting EDW beam profile with the PROFILER. A calculated wedge angle and direct profile comparison were used to describe the deviations in EDW deliveries. The impact of the deviations on typical plans incorporating wedged fields was evaluated by constructing 'equivalent wedges' to the profile deviations using mixed 60 degree and open field beams and performing plan comparisons in Eclipse. Beam symmetry was observed to have a significant impact on wedge angle for small angle wedges, with a 1% symmetry tolerance allowing a 3.4 degree range of wedge angles for a nominal 10 degree wedge. Direct profile comparison allows a more consistent definition of a dose based tolerance range to be applied without angle dependent tolerances. © 2012 American Association of Physicists in Medicine.

  17. Influence of laser beam incidence angle on laser lap welding quality of galvanized steels

    Science.gov (United States)

    Mei, Lifang; Yan, Dongbing; Chen, Genyu; Wang, Zhenhui; Chen, Shuixuan

    2017-11-01

    Based on the characteristics of laser welded structural parts of auto bodies, the influence of variation in laser beam incidence angle on the lap welding performance of galvanized auto-body sheets was studied. Lap welding tests were carried out on the galvanized sheets for auto-body application at different laser beam incidence angles by using the optimal welding parameters obtained through orthogonal experiment. The effects of incidence angle variation on seam appearance, cross-sectional shape, joint mechanical properties and microstructure of weldments were analyzed. In addition, the main factors influencing the value of incidence angle were investigated. According to the results, the weld seams had a good appearance as well as a fine, and uniform microstructure when the laser beam incidence angle was smaller than the critical incidence angle, and thus they could withstand great tensile and shear loads. Moreover, all tensile-shear specimens were fractured in the base material zone. When the laser beam incidence angle was larger than the critical incidence angle, defects like shrinkage and collapse tended to emerge, thereby resulting in the deteriorated weldability of specimens. Meanwhile, factors like the type and thickness of sheet, weld width as well as inter-sheet gap all had a certain effect on the value of laser beam incidence angle. When the sheet thickness was small and the weld width was narrow, the laser beam incidence angle could be increased appropriately. At the same time, small changes in the inter-sheet gap could greatly impact the value of incidence angle. When the inter-sheet gap was small, the laser beam incidence angle should not be too large.

  18. 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

  19. High power, high beam quality solid state lasers for materials processing applications

    Energy Technology Data Exchange (ETDEWEB)

    Hackel, L.A.; Dane, C.B.; Hermann, M.R. [and others

    1994-08-01

    The Laser Science and Technology Department at Lawrence Livermore National Laboratory is developing solid state lasers with high average power and high beam quality. Specific systems include a laser to generate 10 to 14 {angstrom} x-rays for proximity print lithography, a 400 mJ, 500 Hz laser for 130 {angstrom} projection lithography and unique systems for speckle imaging, laser radars and medical treatments.

  20. 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)

  1. Verification of a pencil beam based treatment planning system: output factors for open photon beams shaped with MLC or blocks

    International Nuclear Information System (INIS)

    Hansson, H.

    1999-01-01

    The accuracy of monitor unit calculations from a pencil beam based, three-dimensional treatment planning system (3D TPS) has been evaluated for open irregularly shaped photon fields. The dose per monitor unit was measured in water and in air for x-ray beam qualities from 6 to 15 MV. The fields were shaped either with a multileaf collimator (MLC) or with customized alloy blocks. Calculations from the 3D TPS were compared with measurements. The agreement between calculated and measured dose per monitor unit depended on field size and the amount of blocking and was within 3% for the MLC-shaped fields. The deviation could be traced to limitations in head scatter modelling for the MLC. For fields shaped with alloy blocks, the dose per monitor unit was calculated to be within 1.6% of measured values for all fields studied. The measured and calculated relative phantom scatter for fields with the same equivalent field size were identical for MLC and alloy shaped fields. These results indicate that the accuracy in the TPS calculations for open irregular fields, shaped with MLC or blocks, is satisfactory for clinical situations. (author)

  2. 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.

  3. 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)

  4. Evaluation of Seismic Parameters and Response Modification Factor of Connections in Reduced Beam Section

    OpenAIRE

    Elmira Tavasoli Yousef Abadi

    2016-01-01

    All structural components influencing the inelastic analysis alter response modification factor too. Ductility of connections has been regarded among the factors which have a direct impact on steel frame response modification factor. The experience of recent earthquakes such as the 1994 Northridge earthquake showed that structural connections in steel frame incurred unexpected (brittle) fracture in beam-to-column connection area. One of the methods to improve performance of moment frames is t...

  5. 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.)

  6. Non-Pulse-Leakage 100-kHz Level, High Beam Quality Industrial Grade Nd:YVO4 Picosecond Amplifier

    Directory of Open Access Journals (Sweden)

    Zhenao Bai

    2017-06-01

    Full Text Available A non-pulse-leakage optical fiber pumped 100-kHz level high beam quality Nd:YVO4 picosecond amplifier has been developed. An 80 MHz, 11.5 ps mode-locked picosecond laser is used as the seed with single pulse energy of 1 nJ. By harnessing the double β-BaB2O4 (BBO crystal Pockels cells in both the pulse picker and regenerative amplifier, the seed pulse leakage of the output is suppressed effectively with an adjustable repetition rate from 200 to 500 kHz. Through one stage traveling-wave amplifier, a maximum output power of 24.5 W is generated corresponding to the injected regenerative amplified power of 9.73 W at 500 kHz. The output pulse duration is 16.9 ps, and the beam quality factor M2 is measured to be 1.25 with near-field roundness higher than 99% at the full output power.

  7. High quality quasi-Bessel beam generated by round-tip axicon

    Czech Academy of Sciences Publication Activity Database

    Brzobohatý, Oto; Čižmár, Tomáš; Zemánek, Pavel

    2008-01-01

    Roč. 16, č. 17 (2008), s. 12688-12700 ISSN 1094-4087 R&D Projects: GA MŠk(CZ) LC06007; GA MPO FT-TA2/059 Institutional research plan: CEZ:AV0Z20650511 Keywords : fourier optics and signal processing * spatial filtering * laser beam shaping Subject RIV: BH - Optics, Masers, Laser s Impact factor: 3.880, year: 2008

  8. 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 cutting * CO2 laser beam cutting * 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

  9. Cavity loss factors of non-relativistic beams for Project X

    Energy Technology Data Exchange (ETDEWEB)

    Lunin, A.; Yakovlev, V.; Kazakov, S.; /Fermilab

    2011-03-01

    Cavity loss factor calculation is an important part of the total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the addition of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.

  10. 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)

  11. 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.

  12. 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.

  13. 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

  14. Image quality of two different mobile cone beam computed tomographs for maxillofacial surgery.

    Science.gov (United States)

    Seeberger, Robin; Buchgeister, Markus; Seethaler, Andreas C; Shiozawa, Thomas; Hoffmann, Juergen

    2012-12-01

    We evaluated two mobile cone beam computed tomographs (mCBCT) comparing image quality with respect to radiation dosage. Image quality was analyzed by using different scanning modes. The skulls of three human cadavers were scanned by use of conventional Computed Tomography (CT) as well as with two mobile cone beam computed tomographs (Siemens Arcadis Orbic 3D and Ziehm Vision Vario 3D). Six different acquisition modes with different radiation dosages were used. The axial views of all scans were evaluated by five medical doctors regarding image quality by identifying predefined anatomical structures of the skull. A five-point ranking scale was used. The inter-rater reliability was statistically depicted by Cohen's Kappa coefficient. A Wilcoxon signed rank test was used to evaluate the rater's results. For evaluating the signal-to-noise ratio (SNR) a Catphan 600 reference body with two different inlays was used. Comparing the mCBCTs, the image quality of the Siemens Arcadis Orbic 3D in high-dosage mode received the best score (median: 2.27). The inter-rater reliability was fair (Kappa=-0.030 to 0.328). The Wilcoxon test showed significant (p<0.05) different median rating values in 18 out of 21 imaging modes. The SNR was higher (better) in the high-dosage modes. Intra-operative 3D imaging by using mCBCT for maxillofacial surgery in low-dose mode acquisition is adequate in terms of signal-to-noise ratio and image quality. The image quality does not correlate in a linear manner with a higher radiation dosage. Surgeons using this technique should gather their own experience with the different acquisition modes. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  15. 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

  16. 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

  17. Comparative assessment of subjective image quality of cross-sectional cone-beam computed tomography scans

    International Nuclear Information System (INIS)

    Kamburoglu, K.; Murat, S.; Kolsuz, E.; Kurt, H.; Paksoy, C.; Yueksel, S.

    2011-01-01

    Since the introduction of cone-beam computed tomography (CBCT), several novel systems with different technical specifications and settings have become commercially available. Therefore, it is essential to evaluate CBCT systems for differences in the subjective quality of images obtained for various dental procedures. We evaluated the subjective image quality of cross-sectional scans obtained from various CBCT systems. Images of three cadaver mandibles were obtained from four different CBCT units: Veraviewepocs 3D 40 x 40 mm field of view (FOV) (voxel size: 0.125 x 0.125 x 0.125 mm), Iluma, low-resolution (voxel size: 0.3 x 0.3 x 0.3 mm), Kodak, 50 x 3.7 cm field of view (FOV) (voxel size: 0.076 x 0.076 x 0.076 mm), and Vatech 12 x 8.5 cm FOV (voxel size: 0.160 x 0.160 x 0.160 mm). We assessed subjective image quality and the visibility of 10 specific features, namely, caries, amalgam restoration, final implant drill, root canal filling, metal crown, mandibular canal, mental foramen, tooth (periodontal ligament space and lamina dura), trabecular pattern, and soft tissue. Images were viewed and scored by five calibrated observers, and image quality was ranked from best to worst. The Veraviewepocs 3D had the highest quality images for most of the assessed features, whereas the Iluma low-resolution scans were rated as the lowest quality images. (author)

  18. 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)

  19. Considerations on Beam Quality Control in MIT X-Ray FEL

    CERN Document Server

    Wang, Dong; Graves, William; Huang, Gang; Wang, Defa; Wu, Juhao; Zwart, Townsend

    2005-01-01

    The next generation of x-ray FEL requires very high quality electron beams for producing unprecedented x-ray radiations. In proposed x-ray FEL facilities, especially those that use multi-stage high gain high harmonic (HGHG) principle to obtain coherence in both transverse and longitudinal dimensions, the arrival timing of electron bunches must be very precise to ensure the seed laser overlap the desired sections of the electron bunch. A scheme is proposed to achieve 10s fs level of arrival timing control level.

  20. 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.

  1. Detector to detector corrections: a comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams

    DEFF Research Database (Denmark)

    Azangwe, Godfrey; Grochowska, Paulina; Georg, Dietmar

    2014-01-01

    Purpose: The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially...... useful as a reference data set for small beam dosimetry measurements. Methods: Dose response of passive and real time detectors was investigated for small field sizes shaped with a micromultileaf collimator ranging from 0.6 × 0.6 cm2 to 4.2 × 4.2 cm2 and the measurements were extended to larger fields...... of up to 10 × 10 cm2. Measurements were performed at 5 cm depth, in a 6 MV photon beam. Detectors used included alanine, thermoluminescent dosimeters (TLDs), stereotactic diode, electron diode, photon diode, radiophotoluminescent dosimeters (RPLDs), radioluminescence detector based on carbon...

  2. 100-watt fiber-based green laser with near diffraction-limited beam quality

    Science.gov (United States)

    Hu, Dan; Eisenberg, Eric; Brar, Khush; Yilmaz, Tolga; Honea, Eric

    2010-02-01

    An air-cooled, light-weight, fiber-based, high power green laser has been prototyped. The system consists of an all-fibercoupled IR pump laser at 1064 nm and a frequency-conversion module in a compact and flexible configuration. The IR laser operates in QCW mode, with 10 MHz pulse repetition frequency and 3-5 ns pulse width, to generate sufficient peak power for frequency doubling in the converter module. The IR laser can produce more than 200 W in a linearlypolarized diffraction-limited output beam with high spectral brightness for frequency conversion. The converter module has an input telescope and an oven with a nonlinear crystal to efficiently convert the 1064-nm IR fiber laser output to 532-nm green output. The IR laser and conversion module are connected via a stainless-steel protected delivery fiber for optical beam delivery and an electrical cable harness for electrical power delivery and system control. The beam quality of the 532 nm output remains near diffraction-limited, with M2green laser sources are expected to enable various scientific, defense and industrial applications.

  3. Effects of electron beam irradiation on the microbial growth and quality of beef jerky during storage

    Science.gov (United States)

    Kim, Hyun-Jin; Chun, Ho-Hyun; Song, Hyeon-Jeong; Song, Kyung-Bin

    2010-11-01

    Electron beam irradiation was applied to improve the microbial safety of beef jerky during storage. Beef jerky samples were irradiated at doses of 1, 3, 5, and 10 kGy and stored at 20 °C for 60 d. Microbiological data indicated that the populations of total aerobic bacteria significantly decreased with increasing irradiation dosage. In particular, the populations of total aerobic bacteria were significantly decreased by 1.76 log CFU/g at 10 kJ/m 2, compared to the control. Color measurements showed reduced Hunter L and a values of beef jerky for all the treatments during storage, and the Hunter L, a, and b values of beef jerky were not significantly different among the treatments. Sensory evaluation results also showed that electron beam irradiation did not affect sensory scores in overall during storage. Therefore, the results suggest that electron beam irradiation could be useful in improving the microbial safety without impairing the quality of beef jerky during storage.

  4. Effects of electron beam irradiation on the microbial growth and quality of beef jerky during storage

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Jin; Chun, Ho-Hyun; Song, Hyeon-Jeong [Department of Food Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Song, Kyung-Bin, E-mail: kbsong@cnu.ac.k [Department of Food Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2010-11-15

    Electron beam irradiation was applied to improve the microbial safety of beef jerky during storage. Beef jerky samples were irradiated at doses of 1, 3, 5, and 10 kGy and stored at 20 {sup o}C for 60 d. Microbiological data indicated that the populations of total aerobic bacteria significantly decreased with increasing irradiation dosage. In particular, the populations of total aerobic bacteria were significantly decreased by 1.76 log CFU/g at 10 kJ/m{sup 2}, compared to the control. Color measurements showed reduced Hunter L and a values of beef jerky for all the treatments during storage, and the Hunter L, a, and b values of beef jerky were not significantly different among the treatments. Sensory evaluation results also showed that electron beam irradiation did not affect sensory scores in overall during storage. Therefore, the results suggest that electron beam irradiation could be useful in improving the microbial safety without impairing the quality of beef jerky during storage.

  5. 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...

  6. 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...... increase in quality factor due to the effect of the internally stored energy are given in special cases. For the air-core antenna of vanishing size, it is shown that the dipole modes are the modes providing the lowest quality factor of all modes. Finally an investigation of the effect of the core...

  7. Factors affecting the quality of cryoprecipitate

    Directory of Open Access Journals (Sweden)

    Rajeswari Subramaniyan

    2017-01-01

    Conclusion: The factor VIII recovery in CRYO improves significantly with higher baseline factor VIII: C levels, blood group A donor, and rapid freezing using blast freezer. Rapid freezing also increases the fibrinogen yield.

  8. 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.

  9. 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....

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Sub; Kwon, Hyok Rak; Sim, Woo Hyoun; Oh, Seung Hyoun; Lee, Ji Youn; Jeon, Kug Jin; Kim, Kee Deog; Park, Chang Seo [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Yensei University, Seoul (Korea, Republic of)

    2000-09-15

    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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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 [Korea Atomic Energy Research Institte, Jeongeup (Korea, Republic of); Park, Jin Gyu [Korea University, Seoul (Korea, Republic of)

    2009-06-15

    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.

  16. Counter-crossing injection for stable high-quality electron beam generation via laser-plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kotaki, H; Daito, I; Hayashi, Y; Ma, J; Chen, L-M; Kando, M; Esirkepov, T Z; Fukuda, Y; Homma, T; Pirozhkov, A; Koga, J K; Nakajima, K; Daido, H; Bulanov, S V [Advanced Photon Research Center, Japan Atomic Energy Agency, Kizugawa, Kyoto (Japan)], E-mail: kotaki.hideyuki@jaea.go.jp

    2008-05-01

    Counter-crossing injection, which is a realistic setup for applications, by two sub-relativistic laser pulses colliding at an angle of 45 degrees is demonstrated. The collision of the two laser pulses generates a high-quality electron beam with high reproducibility. The generated monoenergetic electron beam has a peak energy of 14.4 MeV, an energy spread of 10.6%, a charge of 21.8 pC, a normalized emittance of 1.6 {pi} mm mrad, and a reproducibility of 50%. The electron beam generation is unfolded with two-dimensional-particle-in-cell simulations. The laser pulses in plasma are self-focused to higher intensity when the laser power is above the threshold for relativistic self-focusing. The collision of the self-focused laser pulses generates a high-quality electron beam with high reproducibility.

  17. 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 ...

  18. 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 ...

  19. Understanding the Institutional-Level Factors of Urban School Quality

    Science.gov (United States)

    Gottfried, Michael A.

    2012-01-01

    Background/Context: This article addresses which school-level factors contribute to school quality. Previous research has focused on assessing the effects of school-level variables on student-level quality (e.g., achievement). However, the field has been limited in not evaluating the effects of school-level factors directly on measured…

  20. 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.)

  1. Analysis on Factors Affecting the Self-Repair Capability of SMA Wire Concrete Beam

    Directory of Open Access Journals (Sweden)

    Li Sun

    2013-01-01

    Full Text Available Crack expansion of concrete is the initial damage stage of structures, which may cause greater damage to structures subject to long-term loads or under extreme conditions. In recent years, the application of intelligent materials to crack self-repair has become a hotspot among researchers. In order to study the influence of factors on the self-repair capability of shape memory alloy (SMA wire concrete beam, both theoretical and experimental methods were employed for analysis. For the convenience of experiment, composite materials (epoxy cement mortar and silicone polymer clay instead of concrete were used. The SMA wires were externally installed on and internally embedded in epoxy resin cement mortar beams and silicone polymer clay beams. Comparison of crack repair situation between two installation methods turns out that both methods possess their own advantages and disadvantages and should be employed according to the actual situation. The influence of unbonded length on the self-repair capability of embedded type SMA wire beams and the necessary minimum unbonded length to achieve self-repair function were studied. The results state clearly that the longer the unbonded length is, the better the crack repair situation is.

  2. 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…

  3. 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.

  4. A methodology for analysis of defective pipeline by introducing stress concentration factor into beam-pipe finite element formulation

    Directory of Open Access Journals (Sweden)

    Hsu Yang Shang

    2016-06-01

    Full Text Available This work proposes a methodology for defective pipe elastoplastic analysis using the Euler Bernoulli beam-pipe element formulation. The virtual work equation is modified to incorporate the stress concentration factor in beam-pipe element formulation. The stress concentration factor is evaluated a priori by a 2D or 3D finite element model according to the defect profile. In this work, a semicircular defect and a rectangular defect are considered. The stress concentration factor is inserted into the beam-pipe element elastoplastic formulation, and several applications are presented to show the applicability of the proposed method.

  5. 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.

  6. 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

  7. 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)

  8. 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.

  9. 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.

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

    Science.gov (United States)

    Ahmad, Misbah; Hussain, Amjad; Muhammad, Wazir; Rizvi, Syed Qaisar Abbas; Matiullah

    2010-01-01

    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. PMID:20177568

  11. Fluence Correction Factors and Stopping Power Ratios for Clinical Ion Beams

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Hansen, David Christoffer; Sobolevsky, Nikolai

    2011-01-01

    Background. In radiation therapy, the principal dosimetric quantity of interest is the absorbed dose to water. Therefore, a dose conversion to dose to water is required for dose deposited by ion beams in other media. This is in particular necessary for dose measurements in plastic phantoms...... for increased positioning accuracy, graphite calorimetry being developed as a primary standard for dose to water dosimetry, but also for the comparison of dose distributions from Monte Carlo simulations with those of pencil beam algorithms. Material and methods. In the conversion of absorbed dose to phantom...... material to absorbed dose to water the water-to-material stopping power ratios (STPR) and the fluence correction factors (FCF) for the full charged particle spectra are needed. We determined STPR as well as FCF for water to graphite, bone (compact), and PMMA as a function of water equivalent depth, zw...

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

    DEFF Research Database (Denmark)

    Kováts, Daniella; Császár, Noémi; Haller, József

    2017-01-01

    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...... with the WHO-5 Well-being Index (WHOQOL-5), Diener Satisfaction with Life Scale (SwLS), and the Quality of Life in Epilepsy-31 Questionnaire (Qolie-31). We investigated their association with demographic characteristics, general health status, epilepsy, and its treatment. The impact of these factors on illness...... associations with epilepsy-related factors. All four categories of factors were associated with Qolie-31 and IPQ scores. Factors had an additive impact on IPQ, but not on Qolie-31. SIGNIFICANCE: Our findings reveal interactions between the method of life quality assessment and the factors that are identified...

  13. 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.

  14. 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)

  15. 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

  16. Examination of the properties of IMRT and VMAT beams and evaluation against pre-treatment quality assurance results

    International Nuclear Information System (INIS)

    Crowe, S B; Kairn, T; Langton, C M; Trapp, J V; Middlebrook, N; Sutherland, B; Hill, B; Kenny, J

    2015-01-01

    This study aimed to provide a detailed evaluation and comparison of a range of modulated beam evaluation metrics, in terms of their correlation with QA testing results and their variation between treatment sites, for a large number of treatments. Ten metrics including the modulation index (MI), fluence map complexity, modulation complexity score (MCS), mean aperture displacement (MAD) and small aperture score (SAS) were evaluated for 546 beams from 122 intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) treatment plans targeting the anus, rectum, endometrium, brain, head and neck and prostate. The calculated sets of metrics were evaluated in terms of their relationships to each other and their correlation with the results of electronic portal imaging based quality assurance (QA) evaluations of the treatment beams. Evaluation of the MI, MAD and SAS suggested that beams used in treatments of the anus, rectum, head and neck were more complex than the prostate and brain treatment beams. Seven of the ten beam complexity metrics were found to be strongly correlated with the results from QA testing of the IMRT beams (p < 0.00008). For example, values of SAS (with multileaf collimator apertures narrower than 10 mm defined as ‘small’) less than 0.2 also identified QA passing IMRT beams with 100% specificity. However, few of the metrics are correlated with the results from QA testing of the VMAT beams, whether they were evaluated as whole 360° arcs or as 60° sub-arcs. Select evaluation of beam complexity metrics (at least MI, MCS and SAS) is therefore recommended, as an intermediate step in the IMRT QA chain. Such evaluation may also be useful as a means of periodically reviewing VMAT planning or optimiser performance. (paper)

  17. Verification of dose output and beam quality indicator in linear accelerators; Verificacao do fator de calibracao e indicador de qualidade do feixe de aceleradores lineares

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Maria da Penha [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil)]. E-mail: mpenhas@hotmail.com; Mota, Helvecio Correa [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil); Almeida, Carlos Eduardo V. de [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Lab. de Ciencias Radiologicas

    2001-10-01

    A quality assurance program is a mandatory prerequisite for obtaining the high level of accuracy required for radiotherapy. This paper reports the results of part of the routine quality control tests for linear accelerators at the National Cancer Institute, Brazil, performed monthly over a period of two years. These tests included dose output and beam quality indicator. The results were compared with the guidelines of the AAPM TG-40 protocol. The results for the photon beams have shown dose output variations of up to 12%; for electron beams, the largest deviation found was 10%. The fluctuations observed in the beam quality indicator for the electron beams were greater than for the photon beams. These results strongly emphasize the importance of a quality assurance program in radiotherapy services in order to allow prompt corrections of the dose delivered to the patient. (author)

  18. 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.

  19. 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

  20. Image quality and dose for a multisource cone-beam CT extremity scanner.

    Science.gov (United States)

    Gang, Grace J; Zbijewski, Wojciech; Mahesh, Mahadevappa; Thawait, Gaurav; Packard, Nathan; Yorkston, John; Demehri, Shadpour; Siewerdsen, Jeffrey H

    2018-01-01

    This work investigates the dose characteristics and image quality of a multisource cone-beam CT scanner dedicated for extremity imaging. The scanner has an x-ray source with three separate anode-cathode units evenly distributed along the longitudinal direction. A nominal scan protocol fires the three sources sequentially, and a total of 600 projections (200 for each source) are acquired over a source-detector orbit of 210 o . Dose was measured using a Farmer chamber in three CTDI phantoms stacked end-to-end. Measurements were performed at the central and four peripheral locations of a CTDI phantom on the axial plane and repeated along the longitudinal direction. The extent of 3D sampling of the three-source configuration was assessed in the Fourier domain through noise power spectrum measurements from air scans and compared with that from a single-source scan. A modified Defrise phantom and anthropomorphic knee and hand phantoms were used for visual assessment of cone-beam artifacts in the reconstructed images. The dose distribution for the three-source configuration exhibits radial asymmetry on the axial plane consistent with a short-scan geometry. Along the longitudinal direction, the highest dose was measured at the central axial plane where the field of view (FOV) from all three sources overlaps and falls off more slowly toward the end compared to a single-source configuration. The extent of 3D sampling is improved throughout the FOV as each source compensates for missing frequencies from the adjacent source. As a result, the reduction in streak and shading artifacts is apparent in the reconstructed images of all three phantoms. The improvement in image quality from the three-source configuration is most pronounced in joint spaces farther from the central axial plane. Initial assessment of the multisource scanner demonstrated the advantages over single-source designs in a compact scanner with large longitudinal FOV. The reduction in cone-beam artifact is

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. Evaluation of scaling factors for the PTW RW3 plastic mannequin in electron beams; Evaluacion de los factores de puesta en escala para el maniqui plastico RW3 de PTW en haces de electrones

    Energy Technology Data Exchange (ETDEWEB)

    Moral Sanchez, S. C.; Bragado Alvarez, L.; Erzilbengoa, M.; Guisasola Berasategui, M. A.

    2011-07-01

    The International Code of Practice TRS-398 dosimetry published by the International Atomic Energy Agency (IAEA, 2004) are presented as a guide, the values ??for the scaling factor of depth, cp1, the factor scaling of flow, and the nominal density h1, p, 1, for some plastic materials discouraging in any case, its use in electron beam qualities R50> 4 g / cm (10Mev Energies above). In our study, we evaluated these scaling factors for the RW3 plastic phantom (PTW Freiburg).

  8. Additional quality factors for the World Wide Web.

    OpenAIRE

    Fitzpatrick, Ronan

    2000-01-01

    Web site development is maturing from the enthusiastic experimental practice of early years to a more professional discipline, addressing the needs of Web site visitors and owner organisations. Quality is central to this maturing and it is necessary to have a full understanding of the meaning of quality in the context of the ever-changing Web. This paper identifies five new quality factors for the Web (visibility, credibility, intelligibility, engagibility and differentiation), together with ...

  9. Iranian Voice Quality of Life Profile (IVQLP): Factor Analysis.

    Science.gov (United States)

    Dehqan, Ali; Yadegari, Fariba; Scherer, Ronald C; Asgari, Ali; Dabirmoghadam, Payman

    2017-09-01

    An important domain in health-related quality of life evaluations is quality of life perceptions due to having a voice disorder. The objective of this study was to examine the factor structure of the Iranian Voice Quality of Life Profile (IVQLP) based on Exploratory Factor Analysis and confirmatory factor analysis. The study sample consisted of 280 patients (174 males and 106 females) diagnosed with MTD, benign organic disorders such as polyps and nodules, and unilateral vocal fold paralysis and cancer. To evaluate the different dimensions of the IVQLP, a principal component analysis (PCA) was conducted. Confirmatory factor analysis (CFA) was used to investigate the fitting of extracted dimensions and construct validity of the IVQLP. The results showed that the IVQLP has a 4-factor structure. The first factor has 17 items and refers to Emotions. The second factor has 12 items and refers to Individual/Social Relations. The third factor with 6 items refers to Occupation, and the forth with 5 items relates to Psychosomatic characteristics. The conclusion of this study is that the concept of quality of life in Iranian patients with voice disorders is somewhat different from that of Western patients. This difference can be seen in. the large number of items related to an Emotional factor and the identification of a Psychosomatic factor. Copyright © 2017 The Voice Foundation. All rights reserved.

  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. Factors Affecting Soil Quality Maintenance in Northern Katsina State ...

    African Journals Online (AJOL)

    Factors affecting soil quality maintenance in the area according to the findings are natural and man-induced, including agricultural practices in general and deforestation, soil degradation and erosion, as well as biodiversity loss in particular. The results also indicated that values of the selected elements affecting soil quality ...

  12. Surface water quality assessment using factor analysis | Boyacioglu ...

    African Journals Online (AJOL)

    In this study, the factor analysis technique is applied to surface water quality data sets obtained from the Buyuk Menderes River Basin, Turkey, during two different hydrological periods. Results show that the indices which changed the quality of water in two seasons and locations differed. During low-flow conditions, water ...

  13. 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

  14. BUILDABILITY FACTORS THAT INFLUENCE MICRO-LEVEL FORMWORK LABOUR PRODUCTIVITY OF BEAMS IN BUILDING FLOORS

    Directory of Open Access Journals (Sweden)

    Abdulaziz M. Jarkas

    2011-10-01

    Full Text Available Buildability is one of the most important factors that influence labour productivity. Nevertheless, a thorough literature examination revealed a dearth of research concerning the effects of buildability on labour productivity of in situ reinforced concrete construction. Beams are major components of building floors, and the objective of this investigation is to explore the buildability factors that influence their micro-level formwork labour productivity. Therefore, a large volume of productivity data was collected and analysed using a categorical interaction-regression method. As a result, the main and interaction effects of beam repetition, size, intersections and span geometry were determined. The obtained results indicate that the investigated factors significantly influence the forming operation labour efficiency and substantiate the importance of applying design rationalisation, standardisation and repetition concepts to the design stage of construction projects. The findings satisfy the explored activity buildability knowledge gap, which can be used to provide designers with feedback on how well their designs consider the buildability principle requirements, as well as their decision consequences on the forming operation productivity.

  15. 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

  16. 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.

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

    Science.gov (United States)

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

    2013-08-01

    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 1013 He+ cm-2 was established, with both graphene samples becoming highly defective at doses over 5 × 1014 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.

  18. 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.

  19. Odontological light-emitting diode light-curing unit beam quality

    Science.gov (United States)

    de Magalhães Filho, Thales Ribeiro; Weig, Karin de Mello; Werneck, Marcelo Martins; da Costa Neto, Célio Albano; da Costa, Marysilvia Ferreira

    2015-05-01

    The distribution of light intensity of three light-curing units (LCUs) to cure the resin-based composite for dental fillings was analyzed, and a homogeneity index [flat-top factor (FTF)] was calculated. The index is based on the M2 index, which is used for laser beams. An optical spectrum analyzer was used with an optical fiber to produce an x-y power profile of each LCU light guide. The FTF-calculated values were 0.51 for LCU1 and 0.55 for LCU2, which was the best FTF, although it still differed greatly from the perfect FTF=1, and 0.27 for LCU3, which was the poorest value and even lower than the Gaussian FTF=0.5. All LCUs presented notably heterogeneous light distribution, which can lead professionals and researchers to produce samples with irregular polymerization and poor mechanical properties.

  20. 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

  1. Quality and accuracy of cone beam computed tomography gated by active breathing control

    International Nuclear Information System (INIS)

    Thompson, Bria P.; Hugo, Geoffrey D.

    2008-01-01

    The purpose of this study was to evaluate the quality and accuracy of cone beam computed tomography (CBCT) gated by active breathing control (ABC), which may be useful for image guidance in the presence of respiration. Comparisons were made between conventional ABC-CBCT (stop and go), fast ABC-CBCT (a method to speed up the acquisition by slowing the gantry instead of stopping during free breathing), and free breathing respiration correlated CBCT. Image quality was assessed in phantom. Accuracy of reconstructed voxel intensity, uniformity, and root mean square error were evaluated. Registration accuracy (bony and soft tissue) was quantified with both an anthropomorphic and a quality assurance phantom. Gantry angle accuracy was measured with respect to gantry speed modulation. Conventional ABC-CBCT scan time ranged from 2.3 to 5.8 min. Fast ABC-CBCT scan time ranged from 1.4 to 1.8 min, and respiratory correlated CBCT scans took 2.1 min to complete. Voxel intensity value for ABC gated scans was accurate relative to a normal clinical scan with all projections. Uniformity and root mean square error performance degraded as the number of projections used in the reconstruction of the fast ABC-CBCT scans decreased (shortest breath hold, longest free breathing segment). Registration accuracy for small, large, and rotational corrections was within 1 mm and 1 degree sign . Gantry angle accuracy was within 1 degree sign for all scans. For high-contrast targets, performance for image-guidance purposes was similar for fast and conventional ABC-CBCT scans and respiration correlated CBCT.

  2. 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 I FBA 0 1 e CQ I FBA 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 equipment

  3. 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.

  4. Local Recurrence After Primary Proton Beam Therapy in Uveal Melanoma: Risk Factors, Retreatment Approaches, and Outcome.

    Science.gov (United States)

    Seibel, Ira; Cordini, Dino; Rehak, Matus; Hager, Annette; Riechardt, Aline I; Böker, Alexander; Heufelder, Jens; Weber, Andreas; Gollrad, Johannes; Besserer, Angela; Joussen, Antonia M

    2015-10-01

    To evaluate the risk factors, recurrence rates, retreatments, and long-term patient outcomes following proton beam therapy for uveal melanoma. Retrospective interventional case series. All patients treated with primary proton beam therapy for uveal melanoma at the oncology service at Charité-Berlin and Helmholtz-Zentrum-Berlin between May 1998 and December 2008 were reviewed for local recurrence. Of 982 patients, 982 eyes matched the inclusion criteria. The data were obtained from electronic health records, operative reports, discharge letters, and radiation planning. Comparisons of fundus photographs and ultrasound measurements were performed to assess the growth pattern of the tumor and to determine the success of retreatment, in the case that a globe-retaining therapy was undertaken. Of 982 patients, 35 patients (3.6%) developed local recurrence. The median follow-up was 60.7 months (6.0-170.4 months). Local control rate was 96.4% and the overall eye retention rate was 95.0% in this cohort. Local recurrence was correlated with a higher risk for metastasis and reduced survival. Largest tumor diameter was identified as the sole statistically significant risk factor for local recurrence (P = .00001). All globe-retaining retreatment approaches for local recurrence, including proton beam therapy, brachytherapy, and transpupillary thermotherapy used for recurrences at the tumor margins, showed good local tumor control and similar metastasis-free survivals. This study showed that each globe-retaining retreatment approach can result in satisfying local tumor control. In case of early detection of local recurrence, preservation of the globe can be warranted. Therefore, regularly performed follow-ups should be ensured. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Approaching Safety through Quality: Factors Influencing College Student Perceptions.

    Science.gov (United States)

    Ramaswamy, S K; Mosher, G A

    2016-04-01

    Quality management practices have been identified by previous literature as a factor that could potentially reduce the level of safety incidents and hazards in agricultural work environments. The present study used multivariate analysis to examine the effect of independent variables such as quality and safety awareness, work experience, safety and quality management experience, and the perceived importance of safety and quality on the role of quality management practices as a mitigating factor for safety hazards and incidents in agriculture. Variables were measured on a five-point scale using a survey questionnaire. Data were collected from approximately 900 undergraduates enrolled in the College of Agriculture and Life Sciences at a large land grant university in the U.S. The level of student work experience and student perceptions of the importance of quality explained a significant amount of the variance in student views of quality management practices as a mitigating factor for safety hazards and incidents. The findings of this study provide further evidence for using quality management practices as a basis for safety interventions targeted at the agricultural workforce.

  6. Quality control of radiotherapy centres in the Slovak Republic: a dosimetry intercomparison of photon and electron beams under reference conditions

    International Nuclear Information System (INIS)

    Gomola, I.; Kralik, G.; Laginova, V.; Van Dam, J.

    2001-01-01

    The aim of this paper is a dosimetry intercomparison of photon and electron beams under reference conditions as well as quality control of radiotherapy centres in the Slovak Republic. The results obtained in the first check shows that only about 60% of beams are within the acceptance limit. The reasons of discrepancies were traced, in some cases by an on site visit of experts from the NRC, and unacceptable deviations were corrected. The results clearly demonstrate the usefulness of the external dosimetry checks performed with the mailed thermoluminescent dosimeters. Standard deviation of the distribution of the results decreased from SD=4.3% to SD=I.8% for checked photon beams and from SD=8.6% to SD=2.4% for electron beams, respectively, at the end of the project. The dosimetry audits which are performed in regular intervals significantly decreasing a possibility of mistreatment (under-dosage or over-dosage ) of patients due to wrong calibration of radiation therapy beams. In order to keep the reached level of dosimetry precision, it is necessary to establish the external audit in radiotherapy at the national level based on postal TLD dosimetry by transferring the know-how from the international program on quality assurance in radiotherapy dosimetry with the assistance of the IAEA. (authors)

  7. Experimental and Monte Carlo-based determination of the beam quality specifier for TomoTherapyHD treatment units.

    Science.gov (United States)

    Howitz, S; Schwedas, M; Wiezorek, T; Zink, K

    2017-10-12

    Reference dosimetry by means of clinical linear accelerators in high-energy photon fields requires the determination of the beam quality specifier TPR 20,10 , which characterizes the relative particle flux density of the photon beam. The measurement of TPR 20,10 has to be performed in homogenous photon beams of size 10×10cm 2 with a focus-detector distance of 100cm. These requirements cannot be fulfilled by TomoTherapy treatment units from Accuray. The TomoTherapy unit provides a flattening-filter-free photon fan beam with a maximum field width of 40cm and field lengths of 1.0cm, 2.5cm and 5.0cm at a focus-isocenter distance of 85cm. For the determination of the beam quality specifier from measurements under nonstandard reference conditions Sauer and Palmans proposed experiment-based fit functions. Moreover, Sauer recommends considering the impact of the flattening-filter-free beam on the measured data. To verify these fit functions, in the present study a Monte Carlo based model of the treatment head of a TomoTherapyHD unit was designed and commissioned with existing beam data of our clinical TomoTherapy machine. Depth dose curves and dose profiles were in agreement within 1.5% between experimental and Monte Carlo-based data. Based on the fit functions from Sauer and Palmans the beam quality specifier TPR 20,10 was determined from field sizes 5×5cm 2 , 10×5cm 2 , 20×5cm 2 and 40×5cm 2 based on dosimetric measurements and Monte Carlo simulations. The mean value from all experimental values of TPR 20,10 resulted in TPR 20,10 ¯=0.635±0.4%. The impact of the non-homogenous field due to the flattening-filter-free beam was negligible for field sizes below 20×5cm 2 . The beam quality specifier calculated by Monte Carlo simulations was TPR 20,10 =0.628 and TPR 20,10 =0.631 for two different calculation methods. The stopping power ratio water-to-air s w,a Δ directly depends on the beam quality specifier. The value determined from all experimental TPR 20,10 data

  8. 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

  9. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Steiding, Christian; Kolditz, Daniel; Kalender, Willi A., E-mail: willi.kalender@imp.uni-erlangen.de [Institute of Medical Physics, University of Erlangen-Nürnberg, Henkestraße 91, 91052 Erlangen, Germany and CT Imaging GmbH, 91052 Erlangen (Germany)

    2014-03-15

    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. 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)

  12. 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

  13. 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.

  14. The geographical factor in the determination of audit quality

    Directory of Open Access Journals (Sweden)

    Antonio luis duréndez gómez-guillamón

    2012-07-01

    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.

  15. A Projection Quality-Driven Tube Current Modulation Method in Cone-Beam CT for IGRT: Proof of Concept.

    Science.gov (United States)

    Men, Kuo; Dai, Jianrong

    2017-12-01

    To develop a projection quality-driven tube current modulation method in cone-beam computed tomography for image-guided radiotherapy based on the prior attenuation information obtained by the planning computed tomography and then evaluate its effect on a reduction in the imaging dose. The QCKV-1 phantom with different thicknesses (0-400 mm) of solid water upon it was used to simulate different attenuation (μ). Projections were acquired with a series of tube current-exposure time product (mAs) settings, and a 2-dimensional contrast to noise ratio was analyzed for each projection to create a lookup table of mAs versus 2-dimensional contrast to noise ratio, μ. Before a patient underwent computed tomography, the maximum attenuation [Formula: see text] within the 95% range of each projection angle (θ) was estimated according to the planning computed tomography images. Then, a desired 2-dimensional contrast to noise ratio value was selected, and the mAs setting at θ was calculated with the lookup table of mAs versus 2-dimensional contrast to noise ratio,[Formula: see text]. Three-dimensional cone-beam computed tomography images were reconstructed using the projections acquired with the selected mAs. The imaging dose was evaluated with a polymethyl methacrylate dosimetry phantom in terms of volume computed tomography dose index. Image quality was analyzed using a Catphan 503 phantom with an oval body annulus and a pelvis phantom. For the Catphan 503 phantom, the cone-beam computed tomography image obtained by the projection quality-driven tube current modulation method had a similar quality to that of conventional cone-beam computed tomography . However, the proposed method could reduce the imaging dose by 16% to 33% to achieve an equivalent contrast to noise ratio value. For the pelvis phantom, the structural similarity index was 0.992 with a dose reduction of 39.7% for the projection quality-driven tube current modulation method. The proposed method could reduce the

  16. 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

  17. Nanodosimetry-based quality factors for radiation protection in space

    International Nuclear Information System (INIS)

    Schulte, Reinhard W.; Wroe, Andrew J.; Bashkirov, Vladimir A.; Garty, Guy Y.; Breskin, Amos; Chechik, Rachel; Shchemelinin, Sergei; Gargioni, Elisabetta; Grosswendt, Bernd; Rosenfeld, Anatoly B.

    2008-01-01

    Evaluation and monitoring of the cancer risk from space radiation exposure is a crucial requirement for the success of long-term space missions. One important task in the risk calculation is to properly weigh the various components of space radiation dose according to their assumed contribution to the cancer risk relative to the risk associated with radiation of low ionization density. Currently, quality factors of radiation both on the ground and in space are defined by national and international commissions based on existing radiobiological data and presumed knowledge of the ionization density distribution of the radiation field at a given point of interest. This approach makes the determination of the average quality factor of a given radiation field a rather complex task. In this contribution, we investigate the possibility to define quality factors of space radiation exposure based on nanodosimetric data. The underlying formalism of the determination of quality factors on the basis of nanodosimetric data is described, and quality factors for protons and ions (helium and carbon) of different energies based on simulated nanodosimetric data are presented. The value and limitations of this approach are discussed. (orig.)

  18. 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...

  19. Field Quality and Mechanical Analysis of the Beam Separation Dipole for HL-LHC Upgrade

    CERN Document Server

    AUTHOR|(CDS)2086334; Nakamoto, Tatsushi; Xu, Q; Kawamata, H; Todesco, Ezio

    2015-01-01

    High luminosity upgrade of the Large Hadron Collider (HL-LHC) project has been launched to attain a ten times higher integrated luminosity than the current LHC that has been in operation for over ten years. For this goal, the quadruple and dipole magnets around two interaction points, the ATLAS and the CMS, will be upgraded. High Energy Accelerator Research Organization (KEK) is in charge of developing the new superconducting beam separation dipole magnet (D1). The main dipole field of 5.6 T in a large aperture of 150 mm is generated using a cos-theta coil wound with Nb-Ti cables at nominal operating current of 12.0 kA at 1.9 K corresponding to 75% of the load line ratio. The main challenges for the D1 are larger aperture, a high level of iron saturation, radiation resistance, and tight constraints on field quality. This article summarizes the results of a detailed analysis on field error. Electromagnetic simulation with ROXIE was carried out for the 2-D model of the new D1. As possible design changes, a diam...

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

    International Nuclear Information System (INIS)

    Haywood, J

    2016-01-01

    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 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.

  1. 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.

  2. Determination of the quenching correction factors for plastic scintillation detectors in therapeutic high-energy proton beams

    Science.gov (United States)

    Wang, L. L. W.; Perles, L. A.; Archambault, L.; Sahoo, N.; Mirkovic, D.; Beddar, S.

    2012-12-01

    Plastic scintillation detectors (PSDs) have many advantages over other detectors in small field dosimetry due to their high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs undergo a quenching effect which makes the signal level reduced significantly when the detector is close to the Bragg peak where the linear energy transfer (LET) for protons is very high. This study measures the quenching correction factor (QCF) for a PSD in clinical passive-scattering proton beams and investigates the feasibility of using PSDs in depth-dose measurements in proton beams. A polystyrene-based PSD (BCF-12, ϕ0.5 mm × 4 mm) was used to measure the depth-dose curves in a water phantom for monoenergetic unmodulated proton beams of nominal energies 100, 180 and 250 MeV. A Markus plane-parallel ion chamber was also used to get the dose distributions for the same proton beams. From these results, the QCF as a function of depth was derived for these proton beams. Next, the LET depth distributions for these proton beams were calculated by using the MCNPX Monte Carlo code, based on the experimentally validated nozzle models for these passive-scattering proton beams. Then the relationship between the QCF and the proton LET could be derived as an empirical formula. Finally, the obtained empirical formula was applied to the PSD measurements to get the corrected depth-dose curves and they were compared to the ion chamber measurements. A linear relationship between the QCF and LET, i.e. Birks' formula, was obtained for the proton beams studied. The result is in agreement with the literature. The PSD measurements after the quenching corrections agree with ion chamber measurements within 5%. PSDs are good dosimeters for proton beam measurement if the quenching effect is corrected appropriately.

  3. 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...

  4. 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

  5. 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

  6. Verification of relative output factor measurement using Gafchromic films for small-field radiosurgery photon beams.

    Science.gov (United States)

    Abdullah, R.; Sapeei, M. S.; Shukor, N. S. A.; Yusof, M. F. M.; Mohamed, M.; Idris, N. R. N.; Yusoff, A. L.; Zakaria, A.; Aziz, M. Z. A.

    2018-01-01

    Accurate dosimetry of small-field photon beams has always been difficult to achieve, due to the steep dose gradient and absence of lateral electronic equilibrium. The purpose of this study was to verify the measurement of relative output factor (ROF), which is one of the dosimetric parameter required for stereotactic radiosurgery (SRS) treatment planning. The ROFs for Radionics circular cone collimators with diameter in the range of 10.0 to 45.0 mm were measured using Gafchromic EBT2 and EBT3 films. The measurements were then compared with the ROFs obtained using a PinPoint ionisation chamber and Monte Carlo (MC) simulation. From the results, the ROFs measured by the ionisation chamber, EBT2, and EBT3 films were good agreement with the MC simulation, with deviations of less than 1.5, 2.6, and 5.0 % respectively. Based on the film dosimetry, the EBT2 film showed in a more reliable measurement for field size ranging from 15.0 to 45.0 mm, compared with EBT3. As a conclusion, based on the special characteristic of the small-field photon beams, ROF measurement using PinPoint ionisation chamber are being favoured, due to its accuracy. However, the EBT2 film can be used as an alternative, when high spatial resolution is required.

  7. Shear Correction Factors in Creep-Damage Analysis of Beams, Plates and Shells

    Science.gov (United States)

    Altenbach, Holm; Naumenko, Konstantin

    Modern design rules for thin-walled structures which operate at elevated temperatures are based on the demand that the creep and may be the damage behaviour should be taken into account. In the last four decades various models including the scalar or tensor valued hardening and damage variables are established. These models reflect the influence of the deformation or the damage induced anisotropy on the creep response. One problem in creep analysis of thin-walled structures is the selection of the structural mechanics model which has to be adequate to the choice of the constitutive equations. Considering complex loading conditions the structural mechanics model has to reflect for instance the different constitutive behaviour in tension and compression. Below the applicability of classical engineering models for beams, plates and shells to the creep-damage analysis is discussed. It will be shown that a first improvement of the classical approach can be given within the assumptions of the first order shear deformation theory. Based on the beam equations we demonstrate that the shear correction factors have to be modified within the time-step analysis.

  8. High quality factor, fully switchable terahertz superconducting metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Scalari, G., E-mail: scalari@phys.ethz.ch; Maissen, C.; Faist, J. [Institute of Quantum Electronics, Eidgenössische Technische Hochschule Zürich (Switzerland); Cibella, S.; Leoni, R. [Istituto di Fotonica e Nanotecnologie (IFN), CNR, via Cineto Romano 42, 00156 Rome (Italy)

    2014-12-29

    We present a complementary THz metasurface realised with Niobium thin film which displays a quality factor Q = 54 and a fully switchable behaviour as a function of the temperature. The switching behaviour and the high quality factor are due to a careful design of the metasurface aimed at maximising the ohmic losses when the Nb is above the critical temperature and minimising the radiative coupling. The superconductor allows the operation of the cavity with high Q and the use of inductive elements with a high aspect ratio. Comparison with three dimensional finite element simulations highlights the crucial role of the inductive elements and of the kinetic inductance of the Cooper pairs in achieving the high quality factor and the high field enhancement.

  9. 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.

  10. 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

  11. 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 ...

  12. Organisational factors affecting the quality of hospital clinical coding.

    Science.gov (United States)

    Santos, Suong; Murphy, Gregory; Baxter, Kathryn; Robinson, Kerin M

    The influence of organisational factors on the quality of hospital coding using the International Statistical Classification of Diseases and Health Related Problems, 10th Revision, Australian Modification (ICD-10-AM) was investigated using a mixed quantitative-qualitative approach. The organisational variables studied were: hospital specialty; geographical locality; structural characteristics of the coding unit; education, training and resource supports for Clinical Coders; and quality control mechanisms. Baseline data on the hospitals' coding quality, measured by the Performance Indicators for Coding Quality tool, were used as an independent index measure. No differences were found in error rates between rural and metropolitan hospitals, or general and specialist hospitals. Clinical Coder allocation to "general" rather than "specialist" unit coding resulted in fewer errors. Coding Managers reported that coding quality can be improved by: Coders engaging in a variety of role behaviours; improved Coder career opportunities; higher staffing levels; reduced throughput; fewer time constraints on coding outputs and associated work; and increased Coder interactions with medical staff.

  13. Measurement of depth dose factors for various 60-Co and X-ray beams using ion chambers and thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Milu, C.

    1983-06-01

    As the depth dose factors may vary with the type of 60 Co unit (or X-ray generator) several determinations in this direction were done. The depth doses (mGy/s) for 60 Co beam (SSD=80cm) for the depths 5,10,15 and 20 cm were 11.92, 8.25, 5.75 and resp. 4.10 for field size 10x10 cm and 12.70, 9.42, 6.63 and resp. 4.93 for field size 20x20 cm. In X-ray beam, the depth doses (mGy/s) for FSD=50 cm, open-end and field size 10 cm diam. were: 1.78, 0.66, 0.23 and 0.09 for 100 kV (0.143 mm HVL, in air) and depths 5, 10, 15 and resp. 20 cm; 2.61, 1.12, 0.46 and 0.19 for 135 kV and 4.13, 1.88, 0.88 and 0.40 for 180 kV. The quality of the radiation at different depths in the water phantom was determined using a tandem TLD within Cu sleeve and TLD without Cu sleeve. The values obtained ranged from 0.018 mm Cu for 100 kV to 0.170 for 180 kV at depth 5 cm. All determinations were done using an IAEA perspex water tank and Harshaw extruded LiF as detectors. An intercomparison using LiF powder capsules prepared and sent by the IAEA Dosimetry Laboratory was performed too, in order to check the consistency of thermoluminescent dosimetry systems

  14. 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.

  15. Factors affecting the quality of external auditing services

    OpenAIRE

    Alaraji Fedaa Abd Almajid Sabbar; Al-Dulaimi Zaid Yaseen Saud; Sabri Thamer Mahdi Muhamed; Ion Elena Iuliana

    2017-01-01

    This study is aim to adopt knowledge the specific concept to external audit quality and which are the factors that affecting on those qualities in the State of Iraq. As well as, to knowledge the range of depend this job in Iraq on international or local criterion to external audit quality or not. Also, to identify the satisfaction of interested parties about job of audit on service of external audit or not. According to viewpoint external audit the workers in this job and interested parties a...

  16. Quality assurance network in central Europe. External audit on output calibration for photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Izewska, J. [Radiotherapy Dept., Univ. Hospital Gasthuisberg, Leuven (Belgium); Novotny, J. [Radiotherapy Dept., Univ. Hospital Gasthuisberg, Leuven (Belgium); Gwiazdowska, B. [Medical Physics Dept., Cancer Centre, Warsaw (Poland); Kindlova, A. [Dept. of Radiotherapy and Oncology, Univ. Hospital Vinohrady, Prague (Czech Republic); Kontra, G. [National Inst. of Oncology, Budapest (Hungary); Dam, J. van [Radiotherapy Dept., Univ. Hospital Gasthuisberg, Leuven (Belgium); Dutreix, A. [Radiotherapy Dept., Univ. Hospital Gasthuisberg, Leuven (Belgium); Schueren, E. van der [Radiotherapy Dept., Univ. Hospital Gasthuisberg, Leuven (Belgium)

    1995-12-31

    The EROPAQ project for TLD monitoring of photon beams started in June 1994 with the set-up of the TLD system: calibration, reading and evaluation procedures. The acceptance level of {+-}3% was set for the TLD intercomparisons. The policy of the project was to check all beams in 47 participating radiotherapy centres and to recheck all the beams in those centres, where a deviation exceeding {+-}3% occurred in one or more of the beams. Out of 129 beams checked, 100 beams (78%) were found within the {+-}3% limit. Eleven beams show deviations larger than {+-}6%, and immediate corrective action was undertaken. Out of 47 centres checked, 22 did not participate in any external audit in a preceding 5 years. In these centres 68% (34/50) of the total number of {gamma} and X-ray beams checked but only 59% (20/34) of {gamma} beams were within the acceptance level, while in the 25 centres, which participated in an external audit before, these figures were 84% (66/79) and 88% (35/40) respectively. The sources of discrepancies were thoroughly investigated, discussed with the participants and the errors corrected. Poor results were in several cases associated with very old design of radiotherapy units and old dosimetry systems, equipped with inadequate ionization chambers. In several centres, an insufficient training of the physicists in clinical dosimetry was observed. Thanks to the corrective action, a great improvement of calibration of the beams was achieved. Standard deviation of the distribution of the results for all x and {gamma} beams checked decreased from SD = 7.4% at the first check to SD = 2.5% at the second check. (orig.).

  17. 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.

  18. 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

  19. 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

  20. 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)

  1. 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

  2. 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.

  3. Quantification of bone quality using different cone beam computed tomography devices: Accuracy assessment for edentulous human mandibles

    OpenAIRE

    Van Dessel, Jeroen; Nicolielo, Laura Ferreira Pinheiro; Huang, Yan; Slagmolen, Pieter; Politis, Constantinus; Lambrichts, Ivo; Jacobs, Reinhilde

    2016-01-01

    Purpose: To determine the accuracy of the latest cone beam computed tomography (CBCT) machines in comparison to multi-slice computer tomography (MSCT) and micro computed tomography (micro CT) for objectively assessing trabecular and cortical bone quality prior to implant placement. Materials and methods: Eight edentulous human mandibular bone samples were scanned with seven CBCT scanners (3D Accuitomo 170, i-CAT Next Generation, ProMax 3D Max, Scanora 3D, Cranex 3D, Newtom GiANO and Carestrea...

  4. Accessing the Elastic Form-Factors of the $Delta(1232)$ Using the Beam-Normal Asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Dalton, Mark M. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-08-01

    The beam-normal single-spin asymmetry, $B_n$, exists in the scattering of high energy electrons, polarized transverse to their direction of motion, from nuclear targets. To first order, this asymmetry is caused by the interference of the one-photon exchange amplitude with the imaginary part of the two-photon exchange amplitude. Measurements of $B_n$, for the production of a $\\Delta(1232)$ resonance from a proton target, will soon become available from the Qweak experiment at Jefferson Lab and the A4 experiment at Mainz. The imaginary part of two-photon exchange allows only intermediate states that are on-shell, including the $\\Delta$ itself. Therefore such data is sensitive to $\\gamma\\Delta\\Delta$, the elastic form-factors of the $\\Delta$. This article will introduce the form-factors of the $\\Delta$, discuss what might be learned about the elastic form-factors from these new data, describe ongoing efforts in calculation and measurement, and outline the possibility of future measurements.

  5. 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

  6. Application of factor analysis to the water quality in reservoirs

    Science.gov (United States)

    Silva, Eliana Costa e.; Lopes, Isabel Cristina; Correia, Aldina; Gonçalves, A. Manuela

    2017-06-01

    In this work we present a Factor Analysis of chemical and environmental variables of the water column and hydro-morphological features of several Portuguese reservoirs. The objective is to reduce the initial number of variables, keeping their common characteristics. Using the Factor Analysis, the environmental variables measured in the epilimnion and in the hypolimnion, together with the hydromorphological characteristics of the dams were reduced from 63 variables to only 13 factors, which explained a total of 83.348% of the variance in the original data. After performing rotation using the Varimax method, the relations between the factors and the original variables got clearer and more explainable, which provided a Factor Analysis model for these environmental variables using 13 varifactors: Water quality and distance to the source, Hypolimnion chemical composition, Sulfite-reducing bacteria and nutrients, Coliforms and faecal streptococci, Reservoir depth, Temperature, Location, among other factors.

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

    Indian Academy of Sciences (India)

    Parameters suitable for their application in the optical and microwave frequency ranges have been used to compute the frequencies corresponding to the normal modes for the TE and TM modes. Expressions for the quality factors for realistic resonators, i.e., for a dielectric sphere with a non-zero conductivity and a metal ...

  8. Sexually transmitted infections - factors associated with quality of ...

    African Journals Online (AJOL)

    Objectives: To study the factors associated with quality of sexually transmitted infection (STI) care among private general practitioners in Gauteng. Methods: We analysed 1 194 records of patients attending 26 randomly selected GP practices in the first 3 months of 2000 and 2002, for 3 STI syndromes, namely urethral ...

  9. Factors Affecting Soil Quality Maintenance In Northern Katsina State

    African Journals Online (AJOL)

    Factors affecting soil quality maintenance in the area according to the findings are natural and man-induced, including agricultural practices in general and ..... Global warming. 5. 3.03. Total. 165. 100. As the presence of vegetation helps to shield the soil from the direct ray of the sun so it helps to act as wind-brake. The.

  10. A simple quality factor for characterization of thin silicon films

    Czech Academy of Sciences Publication Activity Database

    Kočka, Jan; Mates, Tomáš; Ledinský, Martin; Stuchlíková, The-Ha; Stuchlík, Jiří; Fejfar, Antonín

    2008-01-01

    Roč. 354, 19-25 (2008), s. 2227-2230 ISSN 0022-3093 R&D Projects: GA MŽP(CZ) SN/3/172/05 Keywords : microcrystalline silicon * deposition process * high growth rate * quality evaluation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.449, year: 2008

  11. FACTORS AFFECTING WATER QUALITY IN A WATER SUPPLY NETWORK

    Directory of Open Access Journals (Sweden)

    Artur Jachimowski

    2017-07-01

    Full Text Available An effect of factors determining water quality in the water supply network in Kraków is assessed. Data collected over a four-year research period included quality parameters of water taken from the water distribution system in the period between 1 January 2011 and 31 December 2014. In analysis the supply zones of four municipal water treatment plants in Krakow were considered. The selection of 29 water sampling points within the supply area allowed water quality to to be compared with respect to operational and technological aspects. Factor analysis enabled 4 components explaining correlations between tap water quality variables to be distinguished. It follows from the research performed that the obtained factors applied to 77% of overall water variability. The highest share was assigned to factor 1 that explained in 32% the chemical composition of water under consideration and was correlated with calcium, conductance, nitrates (V, magnesium and to a moderate extent with ∑ THM (with negative sign.

  12. Smartphone laser beam spatial profiler.

    Science.gov (United States)

    Hossain, Md Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas

    2015-11-15

    A simple, low-cost, portable, smartphone-based laser beam profiler for characterizing laser beam profiles is reported. The beam profiler utilizes a phosphor silica glass plate to convert UV light into visible (green) light that can be directly imaged onto an existing smartphone CMOS chip and analyzed using a customized app. 3D printing enables the ready fabrication of the instrument package. The beam's diameter, shape, divergence, beam quality factor, and output power are measured for two UV lasers: a CW 244 nm frequency-doubled Ar ion laser and a pulsed 193 nm ArF exciplex laser. The availability of specialized phosphor converters can extend the instrument from the UV to the near infrared and beyond, and the smartphone platform extends the Internet of Things to map laser beam profiles simultaneously in different locations.

  13. 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.

  14. 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.

  15. The development of an interdepartmental audit as part of a physics quality assurance programme for external beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Bonnett, D.E.; Jaukett, R.J. (Royal Infirmary, Leicester (United Kingdom)); Mills, J.A.; Martin-Smith, P. (Walsgrave Hospital, Coventry (United Kingdom))

    1994-03-01

    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).

  16. 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.

  17. Factors affecting the quality of external auditing services

    Directory of Open Access Journals (Sweden)

    Alaraji Fedaa Abd Almajid Sabbar

    2017-07-01

    Full Text Available This study is aim to adopt knowledge the specific concept to external audit quality and which are the factors that affecting on those qualities in the State of Iraq. As well as, to knowledge the range of depend this job in Iraq on international or local criterion to external audit quality or not. Also, to identify the satisfaction of interested parties about job of audit on service of external audit or not. According to viewpoint external audit the workers in this job and interested parties about external audit in Iraq where practice the profession of external audit under the supervision and control of the board of the profession consists of members appointed by the government ministries no are elected. The study reached to a set of many conclusions, most important of all that the realization external audit in Iraq for importance of external audit quality. Although no existence no concept of specific criterion for quality, whether international or local. Therefore, this study recommends a set of recommendations necessary to adopt uniform criterion for the quality of the external audit job in Iraq, whether international or local, to achieve high quality in audit services and achieving satisfaction of interested parties on those services.

  18. Predictive risk factors for radiation retinopathy and optic neuropathy after proton beam therapy for uveal melanoma.

    Science.gov (United States)

    Seibel, Ira; Cordini, Dino; Hager, Annette; Tillner, Johanna; Riechardt, Aline I; Heufelder, Jens; Davids, Anja M; Rehak, Matus; Joussen, Antonia M

    2016-09-01

    This study was performed in order to evaluate the incidence of radiation retinopathy and optic neuropathy occurring after proton beam therapy for uveal melanoma. Included in this study were all patients who had been treated with primary proton beam therapy for uveal melanoma at the oncology service between May 1998 and June 2014 with a minimum follow-up of 12 months. Excluded were all patients who underwent re-irradiation, or vitrectomy due to exudative retinal detachment or for tumor-resection. During this period, 1127 patients matched the inclusion criteria, of whom 768 (68.1 %) and 463 (41.0 %) developed radiation retinopathy and optic neuropathy after a median time of 18.9 months (2.0-99.84 months) and 19.8 months (0.2-170.4 months), respectively. Mean follow-up was 53.4 months (12-170.4 months). Included were 558 men (49.5 %) and 569 women (50.5 %). Mean age was 61 years (16-89 years). Visual acuity slightly decreased from initial levels of 0.3 logMAR-0.4 logMAR in patients without developing any radiation-induced complication but severely decreased to 1.0 logMAR or 1.5 logMAR in the case of developing radiation retinopathy only or optic neuropathy, respectively. Independent risk factors for radiation retinopathy were a centrally (<2.5 mm from sensitive structures) located tumor or a thick tumor located more than 2.5 mm from sensitive structures, while those for radiation optic neuropathy comprised a short distance and applied dose to the optic disk. The risk for radiation retinopathy is higher in central uveal melanoma. Mid-/peripheral tumors are at high risk for radiation retinopathy and maculopathy if presenting with increased thickness.

  19. 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.

  20. COMP report: CPQR technical quality control guidelines for accelerator-integrated cone-beam systems for verification imaging.

    Science.gov (United States)

    Bissonnette, Jean-Pierre

    2018-03-06

    The Canadian Organization of Medical Physicists, in close partnership with the Canadian Partnership for Quality Radiotherapy has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet in order to ensure an acceptable level of radiation treatment quality. The TQC guidelines have been rigorously reviewed and field tested in a variety of Canadian radiation treatment facilities. The development process enables rapid review and update to keep the guidelines current with changes in technology. This article presents the quality control guideline accelerator-integrated cone-beam systems for verification imaging that has resulted from this process. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  1. 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.

  2. 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.

  3. Factors affecting quality and safety of fresh-cut produce.

    Science.gov (United States)

    Francis, G A; Gallone, A; Nychas, G J; Sofos, J N; Colelli, G; Amodio, M L; Spano, G

    2012-01-01

    The quality of fresh-cut fruit and vegetable products includes a combination of attributes, such as appearance, texture, and flavor, as well as nutritional and safety aspects that determine their value to the consumer. Nutritionally, fruit and vegetables represent a good source of vitamins, minerals, and dietary fiber, and fresh-cut produce satisfies consumer demand for freshly prepared, convenient, healthy food. However, fresh-cut produce deteriorates faster than corresponding intact produce, as a result of damage caused by minimal processing, which accelerates many physiological changes that lead to a reduction in produce quality and shelf-life. The symptoms of produce deterioration include discoloration, increased oxidative browning at cut surfaces, flaccidity as a result of loss of water, and decreased nutritional value. Damaged plant tissues also represent a better substrate for growth of microorganisms, including spoilage microorganisms and foodborne pathogens. The risk of pathogen contamination and growth is one of the main safety concerns associated with fresh-cut produce, as highlighted by the increasing number of produce-linked foodborne outbreaks in recent years. The pathogens of major concern in fresh-cut produce are Listeria monocytogenes, pathogenic Escherichia coli mainly O157:H7, and Salmonella spp. This article describes the quality of fresh-cut produce, factors affecting quality, and various techniques for evaluating quality. In addition, the microbiological safety of fresh-cut produce and factors affecting pathogen survival and growth on fresh-cut produce are discussed in detail.

  4. Quality of life and its influencing factors in patients with

    Directory of Open Access Journals (Sweden)

    LIU Song-yan

    2011-04-01

    Full Text Available 【Abstract】Objective: To observe the quality of life in patients with post-traumatic epilepsy and discuss the influencing factors. Methods: We assessed 105 patients with post-traumatic epilepsy and 100 healthy people as control using Quality of Life Scale-31 (QOL-31, Self-rating Depressing Scale (SDS and Self-rating Anxiety Scale (SAS, and conducted retrospective analysis on the depression, anxiety, site of trauma, control of seizure, EEG and therapeutic compliance. Results: Patients with post-traumatic epilepsy scored much lower than the control group on QOL-31 (P<0.01, but higher than the control group on SDS and SAS (P<0.01. Multiple regression analysis indicated that major influencing factors on the quality of life were anxiety, therapeutic compliance, depression, poor control of epileptic seizure and site of trauma. Conclusions: The quality of life in patients with posttraumatic epilepsy has significantly declined. Doctors should pay attention to psychological and mental problems of patients with epilepsy, such as depression and anxiety, enhancing therapeutic compliance and controlling epileptic seizure, which are the keys to improving prognosis. Key words: Epilepsy, post-traumatic; Quality of life; Anxiety

  5. 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.

  6. 8.2  kW high beam quality quasi-continuous-wave face-pumped Nd:YAG slab amplifier.

    Science.gov (United States)

    Chen, Zhong-Zheng; Xu, Yi-Ting; Guo, Ya-Ding; Wang, Bao-Shan; Xu, Jian; Xu, Jia-Lin; Gao, Hong-Wei; Yuan, Lei; Yuan, Hong-Tao; Lin, Yan-Yong; Xiao, Yun-Sheng; Bo, Yong; Peng, Qin-Jun; Lei, Wen-Qiang; Cui, Da-Fu; Xu, Zu-Yan

    2015-06-01

    An 8 kW level quasi-continuous-wave (QCW) face-pumped 1064 nm slab laser with high beam quality was developed by a master oscillator power amplifier (MOPA) system. A single-mode fiber seed laser was amplified by two-stage single-pass Nd:YAG rod preamplifiers and four face-pumped Nd:YAG slab amplifiers. The slab amplifiers were well designed with uniform pumping and uniform cooling for well-distributed thermal and stress. A dynamically feedbacked optical aberration compensation device was employed to correct low-order optical aberration, and the residue high-order optical aberration was corrected by an adaptive optics system. The QCW MOPA delivered up to an average power of 8.2 kW with a pulse duration of 200 μs at a repetition rate of 400 Hz. The beam quality factor was measured to be β=3.5.

  7. 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.

  8. 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

  9. 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

  10. On the impact of neutron beam divergence and scattering on the quality of transmission acquired tomographic images

    Science.gov (United States)

    Silvani, Maria Ines; Lopes, Ricardo T.; de Almeida, Gevaldo L.; Gonçalves, Marcelo José; Furieri, Rosanne C. A. A.

    2007-10-01

    The impact of the divergence of a thermal neutron beam and the scattered neutrons on the quality of tomographic images acquired by transmission have been evaluated by using a third generation tomographic system incorporating neutron collimators under several different arrangements. The system equipped with a gaseous position sensitive detector has been placed at the main channel outlet of the Argonauta Research Reactor in Instituto de Engenharia Nuclear (CNEN-Brazil) which furnishes a thermal neutron flux of 2.3 × 105 n cm-2 s-1. Experiments have then been conducted using test-objects with well-known inner structure and composition to assess the influence of the collimators arrangement on the quality of the acquired images. Both, beam divergence and scattering - expected to spoil the image quality - have been reduced by using properly positioned collimators between the neutron source and the object, and in the gap between the object and the detector, respectively. The shadow cast by this last collimator on the projections used to reconstruct the tomographic images has been eliminated by a proper software specifically written for this purpose. Improvement of the tomographic images has been observed, demonstrating the effectiveness of the proposed approach to improve their quality by using properly positioned collimators.

  11. 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)

  12. 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

  13. 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.

  14. Evaluation of image quality for different kV cone-beam CT acquisition and reconstruction methods in the head and neck region

    Energy Technology Data Exchange (ETDEWEB)

    Elstroem, Ulrik V.; Muren, Ludvig P. (Dept. of Oncology, Aarhus Univ. Hospital, Aarhus (Denmark); Dept. of Medical Physics, Aarhus Univ. Hospital, Aarhus (Denmark)), e-mail: ulrielst@rm.dk; Petersen, Joergen B. B. (Dept. of Medical Physics, Aarhus Univ. Hospital, Aarhus (Denmark)); Grau, Cai (Dept. of Oncology, Aarhus Univ. Hospital, Aarhus (Denmark))

    2011-08-15

    Purpose. To evaluate the image quality obtained in a standard QA phantom with both clinical and non-clinical cone-beam computed tomography (CBCT) acquisition modes for the head and neck (HN) region as a step towards CBCT-based treatment planning. The impact of deteriorated Hounsfield unit (HU) accuracy was investigated by comparing results from clinical CBCT image reconstructions to those obtained from a pre-clinical scatter correction algorithm. Methods. Five different CBCT acquisition modes on a clinical system for kV CBCT-guided radiotherapy were investigated. Image reconstruction was performed in both standard clinical software and with an experimental reconstruction algorithm with improved beam hardening and scatter correction. Using the Catphan 504 phantom, quantitative measures of HU uniformity, HU verification and linearity, contrast-to-noise ratio (CNR), and spatial resolution using modulation transfer function (MTF) estimation were assessed. To benchmark the CBCT image properties, comparison to standard HN protocols on conventional CT scanners was performed by similar measures. Results. The HU uniformity within a water-equivalent homogeneous region was considerably improved using experimental vs. standard reconstruction, by factors of two for partial scans and four for full scans. Similarly, the amount of capping/cupping artifact was reduced by more than 1.5%. With mode and reconstruction specific HU calibration using seven inhomogeneity inserts comparable HU linearity was observed. CNR was on average 5% higher for experimental reconstruction (scaled with the square-root of dose between modes for both reconstruction methods). Conclusions. Judged on parameters affecting the common diagnostic image properties, improved beam hardening and scatter correction diminishes the difference between CBCT and CT image quality considerably. In the pursuit of CBCT-based treatment adaptation, dedicated imaging protocols may be required

  15. 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.

  16. 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 ( Pcanola meal at doses of 45 kGy decreased ( Pcanola meal at doses of 15 and 30 kGy was improved ( Pcanola meal were more resistant to degradation, compared with an untreated sample. Electron beam irradiation was effective in protecting CP from ruminal degradation and reducing antinutritional factors of irradiated canola meal.

  17. Stroboscopic image capture: Reducing the dose per frame by a factor of 30 does not prevent beam-induced specimen movement in paraffin

    Energy Technology Data Exchange (ETDEWEB)

    Typke, Dieter [Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Gilpin, Christopher J. [Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390 (United States); Downing, Kenneth H. [Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Glaeser, Robert M. [Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States) and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 (United States)]. E-mail: rmglaeser@lbl.gov

    2007-02-15

    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{sub 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 {sub image}(g)/F {sub 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.

  18. 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

  19. 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)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Predictive factors of the dimensions and location of mental foramen using cone beam computed tomography.

    Science.gov (United States)

    Muinelo-Lorenzo, Juan; Fernández-Alonso, Ana; Smyth-Chamosa, Ernesto; Suárez-Quintanilla, Juan Antonio; Varela-Mallou, Jesús; Suárez-Cunqueiro, María Mercedes

    2017-01-01

    The mental foramen (MF) hosts main neurovascular structures, making it of crucial importance for surgical procedures. This study aimed to analyze the factors influencing the dimensions and location of the MF. Cone beam computed tomography (CBCT) scans of 344 patients were examined for MF dimensions, as well as for the distances from the MF to the alveolar crest (MF-MSB), and to the inferior mandibular border (MF-MIB). Gender, mandibular side and presence of accessory mental foramina (AMF) significantly influence MF area. Males, left hemimandibles, and hemimandibles with no AMF had a higher rate of large MF areas (B = - 0.60; p = 0.003, females; B = 0.55; p = 0.005; B = 0.85; p = 0.038). Age, gender and dental status significantly influence MF-MSB distance. The distance decreased as age increased (B = -0.054; p = 0.001), females showed a lower rate of long MF-MSB distances (B = -0.94, p = 0.001), and dentate patients showed a higher rate of long MF-MSB distances (B = 2.27; p = 0.001). Age, gender and emerging angle significantly influenced MF-MIB distance. The distance decreased as age and emerging angle increased (B = -0.01; p = 0.001; B = -0.03; p = 0.001), and females had a lower rate of long MF-MIB distances (B = -1.94, p = 0.001). General and local factors influence the dimensions and location of MF. MF dimensions are influenced by gender, mandibular side, anteroposterior position, and the presence of AMF. Distance from MF to alveolar crest is influenced by gender, age and dental status, while the relative MF position is influenced by age and dental status. CBCT images make it possible to analyze the MF in order to avoid complications during surgical procedures.

  6. Predictive factors of the dimensions and location of mental foramen using cone beam computed tomography.

    Directory of Open Access Journals (Sweden)

    Juan Muinelo-Lorenzo

    Full Text Available The mental foramen (MF hosts main neurovascular structures, making it of crucial importance for surgical procedures. This study aimed to analyze the factors influencing the dimensions and location of the MF.Cone beam computed tomography (CBCT scans of 344 patients were examined for MF dimensions, as well as for the distances from the MF to the alveolar crest (MF-MSB, and to the inferior mandibular border (MF-MIB.Gender, mandibular side and presence of accessory mental foramina (AMF significantly influence MF area. Males, left hemimandibles, and hemimandibles with no AMF had a higher rate of large MF areas (B = - 0.60; p = 0.003, females; B = 0.55; p = 0.005; B = 0.85; p = 0.038. Age, gender and dental status significantly influence MF-MSB distance. The distance decreased as age increased (B = -0.054; p = 0.001, females showed a lower rate of long MF-MSB distances (B = -0.94, p = 0.001, and dentate patients showed a higher rate of long MF-MSB distances (B = 2.27; p = 0.001. Age, gender and emerging angle significantly influenced MF-MIB distance. The distance decreased as age and emerging angle increased (B = -0.01; p = 0.001; B = -0.03; p = 0.001, and females had a lower rate of long MF-MIB distances (B = -1.94, p = 0.001.General and local factors influence the dimensions and location of MF. MF dimensions are influenced by gender, mandibular side, anteroposterior position, and the presence of AMF. Distance from MF to alveolar crest is influenced by gender, age and dental status, while the relative MF position is influenced by age and dental status. CBCT images make it possible to analyze the MF in order to avoid complications during surgical procedures.

  7. 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

  8. 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.

  9. 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

  10. Quality management in the nuclear industry: the human factor

    Energy Technology Data Exchange (ETDEWEB)

    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).

  11. Pharmacological properties of granulocytic colony-stimulating factor pegylated using electron beam synthesis nanotechnologies.

    Science.gov (United States)

    Dygai, A M; Zyuz'kov, G N; Zhdanov, V V; Madonov, P G; Udut, E V; Miroshnichenko, L A; Khrichkova, T Yu; Simanina, E V; Stavrova, L A; Artamonov, A V; Bekarev, A A; Kinsht, D N; Chaikovskiy, A V; Markova, T S; Gurto, R V

    2011-11-01

    Granulocytic CSF pegylated using electron-beam synthesis nanotechnology exhibits pronounced granulomonocytopoiesis-stimulating and SC-mobilizing activity. More potent stimulation of committed precursors against the background of less pronounced activation of polypotent hemopoietic cells is a peculiarity of hemostimulating action of pegylated using electron-beam synthesis nanotechnology granulocytic CSF in comparison with its non-modified analog. The mobilizing effect of pegylated using electron-beam synthesis nanotechnology granulocytic CSF on early progenitor elements surpasses that of non-conjugated cytokine.

  12. 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

  13. 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

  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. Effects of Sealing Run Welding with Defocused Laser Beam on the Quality of T-joint Fillet Weld

    Science.gov (United States)

    Unt, Anna; Poutiainen, Ilkka; Salminen, Antti

    Fillet weld is the predominant weld type used for connecting different elements e.g. in shipbuilding, offshore and bridge structures. One of prevalent research questions is the structural integrity of the welded joint. Post weld improvement techniques are being actively researched, as high stress areas like an incomplete penetration on the root side or fluctuations in penetration depth cannot be avoided. Development of laser and laser-arc hybrid welding processes have greatly contributed to increase of production capacity and reduction of heat-induced distortions by producing single pass full penetration welds in thin- and medium thickness structural steel parts. Present study addresses the issue of how to improve the quality of the fillet welds by welding the sealing run on the root side with defocused laser beam. Welds having incomplete or excessive penetration were produced with several beam angles and laser beam spot sizes on surface. As a conclusion, significant decrease or even complete elimination of the seam irregularities, which act as the failure starting points during service, is achieved.

  16. 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.

  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. 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.

  19. 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

  20. 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.

  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. 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)

  4. 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

  5. Effects of Electron Beam Irradiated Natural Casings on the Quality Characteristics of Emulsion Sausage

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunwook; Kim, Hackyoun; Hwang, Koeun; Choi, Sunmi; Kim, Cheonjei; Choi, Jihun; Choi, Yunsang [Konkuk Univ., Seoul (Korea, Republic of); Lee, Juwoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-07-01

    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.

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

    Indian Academy of Sciences (India)

    Normal modes and quality factors of spherical dielectric resonators. Hθ = A. jωµ0r d dr {√. rJn+(1/2)(kr)} d dθ {P m n (cos θ)} cos mφ,. (12b). Hφ = −. mA. jωµ0r sin θ d dr {√. rJn+(1/2)(kr)} Pm n (cos θ) sin mφ. (12c). Similarly, for the TM modes the field components are given by. Er = n(n + 1)A jωε0εrr3/2. Jn+(1/2)(kr)Pm n (cos ...

  7. A simple quality factor for characterization of thin silicon films

    Czech Academy of Sciences Publication Activity Database

    Kočka, Jan; Mates, Tomáš; Ledinský, Martin; Stuchlíková, The-Ha; Stuchlík, Jiří; Fejfar, Antonín

    2008-01-01

    Roč. 354, 19-25 (2008), s. 2227-2230 ISSN 0022-3093 R&D Projects: GA MŠk(CZ) LC06040; GA ČR(CZ) GD202/05/H003; GA MŠk LC510; GA AV ČR IAA1010413; GA AV ČR IAA1010316; GA MŽP(CZ) SN/3/172/05 Institutional research plan: CEZ:AV0Z10100521 Keywords : microcrystalline silicon * deposition process * high growth rate * quality evaluation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.449, year: 2008

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  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. 70-Watt green laser with near diffraction-limited beam quality

    Science.gov (United States)

    Hu, Dan; Eisenberg, Eric; Madasamy, Pratheepan; Mead, Roy; Honea, Eric

    2009-02-01

    A 70-Watt green laser with M2green laser consists of an all-fiber-based IR pump laser at 1064 nm and a frequency-conversion module in a compact and flexible configuration. The IR laser produces up to 150 Watts in a polarized diffraction-limited output beam with high spectral brightness for frequency conversion. The IR laser is operating under QCW mode, e.g. 10 MHz with 3~5 ns pulse width or 700 MHz with 50 ps pulse width, to generate sufficient peak power for frequency doubling in the converter module. The IR laser and conversion module are connected via a 5-mm stainless-steel protected delivery fiber for optical beam delivery and an electrical cable harness for electrical power delivery and system control. Both the IR laser and converter module are run through embedded software that controls laser operations such as warm up and shut down. System overview and full characterization results will be presented. Such a high power green laser with near diffraction-limited output in a compact configuration will enable various scientific as well as industrial applications.

  17. Improving the quality of radiographic images acquired with conical radiation beams through divergence correction and filtering

    Science.gov (United States)

    Silvani, M. I.; Almeida, G. L.; Latini, R. M.; Bellido, A. V. B.; Souza, E. S.; Lopes, R. T.

    2015-07-01

    Earlier works have shown the feasibility to correct the deformation of the attenuation map in radiographs acquired with conical radiation beams provided that the inspected object could be expressed into analytical geometry terms. This correction reduces the contribution of the main object in the radiograph, allowing thus the visualization of its otherwise concealed heterogeneities. However, the non-punctual character of the source demanded a cumbersome trial-and-error approach in order to determine the proper correction parameters for the algorithm. Within this frame, this work addresses the improvement of radiographs of specially tailored test-objects acquired with a conical beam through correction of its divergence by using the information contained in the image itself. The corrected images have afterwards undergone a filtration in the frequency domain aiming at the reduction of statistical fluctuation and noise by using a 2D Fourier transform. All radiographs have been acquired using 165Dy and 198Au gamma-ray sources produced at the Argonauta research reactor in Institutode Engenharia Nuclear - CNEN, and an X-ray sensitive imaging plate as detector. The processed images exhibit features otherwise invisible in the original ones. Their processing by conventional histogram equalization carried out for comparison purposes did not succeed to detect those features.

  18. Mie Plasmons: Modes Volumes, Quality Factors, and Coupling Strengths (Purcell Factor to a Dipolar Emitter

    Directory of Open Access Journals (Sweden)

    G. Colas des Francs

    2012-01-01

    Full Text Available Using either quasistatic approximation or exact Mie expansion, we characterize the localized surface plasmons supported by a metallic spherical nanoparticle. We estimate the quality factor Qn and define the effective volume Vn of the nth mode in such a way that coupling strength with a neighbouring dipolar emitter is proportional to the ratio Qn/Vn (Purcell factor. The role of Joule losses, far-field scattering, and mode confinement in the coupling mechanism is introduced and discussed with simple physical understanding, with particular attention paid to energy conservation.

  19. Expected quality factor of a simple tuned oscillator.

    Science.gov (United States)

    Tan, Kia Hock

    2011-05-01

    A positive feedback system oscillating under self-sustained mode is shown to have an extremely high gain. Modeled as one port, the expected Q is much higher than the loaded Q-factor of the resonator. With just thermal noise present, random phase/frequency deviation is linear. Centered about the oscillator frequency omega/(0), noise frequency on both sides is more amplified with decreasing separation distance. Ultimately, frequency pulling may result in synchronous locking with hysteresis, which occurs because a real oscillator displays a truncated limiting curve. Once locked onto a signal, smaller levels are ignored. A new approach to the design and characterization of a simple tuned oscillator is offered: According to the phenomenon of injection locking, there exists an expected quality factor relating the shape of the truncated limiting curve to an ideal curve. In this paper, synthesis and innovative analytical methods of academic interest are revealed: 1) application of the transducer loss method is revised to establish a new method for oscillator characterization; 2) a transparent method of normalizing a two-port network in the presence of white noise is developed; and 3) in quartz crystal controlled oscillators, characterization of the noise originating from an equivalent noise-resistance determined from parameter of the quartz crystal is proposed. It is shown that the two-port model can also be approximated on a one-port basis. In conclusion, a sample of closed-form estimation of expected Q-factor order of magnitude of piezoelectric resonator oscillators is calculated.

  20. 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....

  1. 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)

  2. Examining the Factor Structure and Hierarchical Nature of the Quality of Life Construct

    Science.gov (United States)

    Wang, Mian; Schalock, Robert L.; Verdugo, Miguel A.; Jenaro, Christina

    2010-01-01

    There is considerable debate in the area of individual quality of life research regarding the factor structure and hierarchical nature of the quality of life construct. Our purpose in this study was to test via structural equation modeling an a priori quality of life model consisting of eight first-order factors and one second-order factor. Data…

  3. [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.

  4. 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.

  5. 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)

  6. 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.

  7. Patient factors associated with quality of life in atrial fibrillation.

    Science.gov (United States)

    Randolph, Tiffany C; Simon, DaJuanicia N; Thomas, Laine; Allen, Larry A; Fonarow, Gregg C; Gersh, Bernard J; Kowey, Peter R; Reiffel, James A; Naccarelli, Gerald V; Chan, Paul S; Spertus, John A; Peterson, Eric D; Piccini, Jonathan P

    2016-12-01

    As treatment options for atrial fibrillation (AF) increase, more attention is focused on patients' experiences and quality of life (QoL). However, little is known about the factors associated with these outcomes. The Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) is a disease-specific QoL tool for AF, with domain and summary scores ranging from 0 (the worst QoL) to 100. Using multivariable linear regression, we evaluated factors associated with baseline AFEQT Summary and Subscale Scores in ORBIT AF, a large, community-based AF registry. Independent associations were reported as coefficient estimates in scores and 95% confidence intervals (CI). Overall, AFEQT was assessed in 2007 AF outpatients from 99 sites. Median age (IQR) was 76 years (67-82) and 43% were female. The median AFEQT summary score was 82 (67-94). Female sex, younger age, new onset AF, higher heart rate, obstructive sleep apnea, symptomatic heart failure (HF), chronic obstructive pulmonary disease and coronary artery disease were all independently associated with reduced QoL. Female sex [Estimate -7.03, 95% CI (-9.31, -4.75)] and new onset versus permanent AF [Estimate -7.44, 95% CI (-11.03, -3.84)] were independently associated with increased symptoms. NYHA Class III or IV HF [Estimate -14.44, 95% CI (-19.46, -8.76)] and female sex [Estimate -7.91, 95% CI (-9.95, -5.88)] were most independently associated with impaired daily activities. QoL in patients with AF varies widely and is associated with several patient factors. Understanding patient factors independently associated with worse QoL can be a foundation for tailoring treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Enhancing selectivity of infrared emitters through quality-factor matching

    Science.gov (United States)

    Sakr, Enas; Zhou, Zhiguang; Bermel, Peter

    2015-09-01

    It has recently been proposed that designing selective emitters with photonic crystals (PhCs) or plasmonic metamaterials can suppress low-energy photon emission, while enhancing higher-energy photon emission. Here, we will consider multiple approaches to designing and fabricating nanophotonic structures concentrating infrared thermal radiation at energies above a critical threshold. These are based on quality factor matching, in which one creates resonant cavities that couple light out at the same rate that the underlying materials emit it. When this quality-factor matching is done properly, emissivities can approach those of a blackbody, but only within a selected range of thermal photon energies. One potential application is for improving the conversion of heat to electricity via a thermophotovoltaic (TPV) system, by using thermal radiation to illuminate a photovoltaic (PV) diode. In this study, realistic simulations of system efficiencies are performed using finite-difference time domain (FDTD) and rigorous coupled wave analysis (RCWA) to capture both thermal radiation and PV diode absorption. We first consider a previously studied 2D molybdenum photonic crystal with a commercially-available silicon PV diode, which can yield TPV efficiencies up to 26.2%. Second, a 1D-periodic samarium-doped glass emitter with a gallium antimonide (GaSb) PV diode is presented, which can yield efficiencies up to 38.5%. Finally, a 2D tungsten photonic crystal with a 1D integrated, chirped filter and the GaSb PV diode can yield efficiencies up to 38.2%; however, the fabrication procedure is expected to be more challenging. The advantages and disadvantages of each strategy will be discussed.

  9. 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

  10. 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)

  11. 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.

  12. Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance.

    Science.gov (United States)

    Barnes, Michael P; Greer, Peter B

    2016-03-08

    In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved in-plane and cross-plane profiles during plan delivery from which symmetry could be determined. Time-resolved symmetry measurements were performed throughout static field exposures at cardinal gantry angles, conformal arcs with constant dose rate and gantry speed, and during a VMAT test plan with gantry speed and dose rate modulation. Measurements were performed for both clockwise and counterclockwise gantry rotation and across four Varian 21iX lin-acs. The symmetry was found to be generally constant throughout the static field exposures to within 0.3% with an exception on one linac of up to 0.7%. Agreement in symmetry between cardinal angles was always within 1.0% and typically within 0.6%. During conformal arcs the results for clockwise and counterclockwise rotation were in agreement to within 0.3%. Both clockwise and counterclockwise tended to vary in similar manner by up to 0.5% during arc consistent with the cardinal gantry angle static field results. During the VMAT test plan the symmetry generally was in agreement with the conformal arc results. Greater variation in symmetry was observed in the low-dose-rate regions by up to 1.75%. All results were within clinically acceptable levels using the tolerances of NCS Report 24 (2015).

  13. 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)

  14. Effects of Electron Beam Irradiation on Zearalenone and Ochratoxin A in Naturally Contaminated Corn and Corn Quality Parameters

    Directory of Open Access Journals (Sweden)

    Xiaohu Luo

    2017-02-01

    Full Text Available Zearalenone (ZEN and ochratoxin A (OTA are secondary toxic metabolites widely present in grains and grain products. In this study, the effects of electron beam irradiation (EBI on ZEN and OTA in corn and the quality of irradiated corn were investigated. Results indicated that EBI significantly affected ZEN and OTA. The degradation rates of ZEN and OTA at 10 kGy in solution were 65.6% and 75.2%, respectively. The initial amounts significantly affected the degradation rate. ZEN and OTA in corn were decreased by the irradiation dose, and their degradation rates at 50 kGy were 71.1% and 67.9%, respectively. ZEN and OTA were more easily degraded in corn kernel than in corn flour. Moisture content (MC played a vital role in ZEN and OTA degradation. High MC was attributed to high ZEN and OTA degradation. The quality of irradiated corn was evaluated on the basis of irradiation dose. L* value changed, but this change was not significant (p > 0.05. By contrast, a* and b* decreased significantly (p < 0.05 with irradiation dose. The fatty acid value increased significantly. The pasting properties, including peak, trough, breakdown, and final and setback viscosities, were also reduced significantly (p < 0.05 by irradiation. Our study verified that EBI could effectively degrade ZEN and OTA in corn. Irradiation could also affect corn quality.

  15. Assessment of image quality in soft tissue and bone visualization tasks for a dedicated extremity cone-beam CT system.

    Science.gov (United States)

    Demehri, S; Muhit, A; Zbijewski, W; Stayman, J W; Yorkston, J; Packard, N; Senn, R; Yang, D; Foos, D; Thawait, G K; Fayad, L M; Chhabra, A; Carrino, J A; Siewerdsen, J H

    2015-06-01

    To assess visualization tasks using cone-beam CT (CBCT) compared to multi-detector CT (MDCT) for musculoskeletal extremity imaging. Ten cadaveric hands and ten knees were examined using a dedicated CBCT prototype and a clinical multi-detector CT using nominal protocols (80 kVp-108mAs for CBCT; 120 kVp- 300 mAs for MDCT). Soft tissue and bone visualization tasks were assessed by four radiologists using five-point satisfaction (for CBCT and MDCT individually) and five-point preference (side-by-side CBCT versus MDCT image quality comparison) rating tests. Ratings were analyzed using Kruskal-Wallis and Wilcoxon signed-rank tests, and observer agreement was assessed using the Kappa-statistic. Knee CBCT images were rated "excellent" or "good" (median scores 5 and 4) for "bone" and "soft tissue" visualization tasks. Hand CBCT images were rated "excellent" or "adequate" (median scores 5 and 3) for "bone" and "soft tissue" visualization tasks. Preference tests rated CBCT equivalent or superior to MDCT for bone visualization and favoured the MDCT for soft tissue visualization tasks. Intraobserver agreement for CBCT satisfaction tests was fair to almost perfect (κ ~ 0.26-0.92), and interobserver agreement was fair to moderate (κ ~ 0.27-0.54). CBCT provided excellent image quality for bone visualization and adequate image quality for soft tissue visualization tasks. • CBCT provided adequate image quality for diagnostic tasks in extremity imaging. • CBCT images were "excellent" for "bone" and "good/adequate" for "soft tissue" visualization tasks. • CBCT image quality was equivalent/superior to MDCT for bone visualization tasks.

  16. 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

  17. Comparison of Image Quality and Diagnostic Performance of Cone-Beam CT during Drug-Eluting Embolic Transarterial Chemoembolization and Multidetector CT in the Detection of Hepatocellular Carcinoma.

    Science.gov (United States)

    Lucatelli, Pierleone; Argirò, Renato; Ginanni Corradini, Stefano; Saba, Luca; Cirelli, Carlo; Fanelli, Fabrizio; Ricci, Carmelo; Levi Sandri, Giovanni Battista; Catalano, Carlo; Bezzi, Mario

    2017-07-01

    To compare image quality and diagnostic performance of cone-beam computed tomography (CT) and multidetector CT in the detection of hypervascular hepatocellular carcinoma (HCC) in patients with cirrhosis undergoing transarterial chemoembolization with drug-eluting embolic agents. Fifty-five consecutive patients referred for chemoembolization of hypervascular HCC were prospectively enrolled. Imaging included preprocedural multidetector CT within 1 month before planned treatment, intraprocedural cone-beam CT, and 1-month follow-up multidetector CT. Analysis of image quality was performed with calculations of lesion-to-liver contrast-to-noise ratio (LLCNR) and lesion-to-liver signal-to-noise-ratio (LLSNR). One-month follow-up multidetector CT was considered the reference standard for the detection of HCC nodules. Median LLCNR values were 3.94 (95% confidence interval [CI], 3.06-5.05) for preprocedural multidetector CT and 6.90 (95% CI, 5.17-7.77) for intraprocedural cone-beam CT (P cone-beam CT (P cone-beam CT detected 15 additional hypervascular nodules that were also visible on 1-month follow-up multidetector CT. Cone-beam CT has a significantly higher diagnostic performance compared with preprocedural multidetector CT in the detection of HCCs and can influence management of patients with cirrhosis by identifying particularly aggressive tumors. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

  18. Data Quality Monitoring Framework for ATLAS Experiment: Performance Achieved with Colliding Beams at LHC

    CERN Document Server

    Corso-Radu, A; The ATLAS collaboration; Ilchenko, Y; Kolos, S; Okawa, H; Slagle, K; Taffard, A

    2010-01-01

    With the delivery of the first proton-proton collisions by the LHC, the ATLAS collaboration had the opportunity to operate the detector under the environment it was designed for. These first runs have been of great interest not only for the high energy physics outcome, but also were used to perform a general commissioning of the system. The online data quality monitoring framework (DQMF) is a highly scalable distributed framework that is used to assess the quality of the data and the operational conditions of the detector, trigger and data acquisition system. DQMF provides quick feedback to the user about the correct functioning and performance of different parts of the detector, it quickly spots problems related with data quality and allows one to determine the origin of these problems. DQMF performs over forty thousand advanced data quality checks at a rate that depends on the histogram update frequency and it displays histograms and results of these checks on several dozens of monitors installed in the mai...

  19. STRESS DISTRIBUTIONS AND STRESS CONCENTRATION FACTORS IN A SIMPLE BEAM WITH A CIRCULAR HOLE SUBJECTED TO CONSTANT BENDING MOMENT

    Directory of Open Access Journals (Sweden)

    Seçil ERİM

    1998-03-01

    Full Text Available In this study, a beam subjected to pure bending with a circular hole on its transverse axis, is analyzed by the Finite Element Method. The hole is shifted to various locations along the transverse axis and two different materials, namely isotropic (steel and orthotropic (graphite-epoxy, are used as beam material. Stress distribution and stress concentration factors around the hole are determined for each case. In order to establish the effect of fiber reinforcing angle on the stress distribution, the examination is repeated at various reinforcing angles between 0° and 90° for graphite-epoxy. Denoting the distance between the longitudinal axis and the center of the hole as b, the value of the critical hole diameter which leads to the maximum theoretical bending moment is determined by using the Finite Element Method. Furthermore, the critical distance b which will create the maximum theoretical bending moment for a constant hole diameter of 10 mm, is calculated for steel and each reinforcing angle of the composite beam.

  20. Comparison of the Diagnostic Image Quality of the Canine Maxillary Dentoalveolar Structures Obtained by Cone Beam Computed Tomography and 64-Multidetector Row Computed Tomography

    Science.gov (United States)

    Soukup, Jason W.; Drees, Randi; Koenig, Lisa J.; Snyder, Christopher J.; Hetzel, Scott; Miles, Chanda R.; Schwarz, Tobias

    2016-01-01

    Summary The objective of this blinded study was to validate the use of cone beam computed tomography (CT) for imaging of the canine maxillary dentoalveolar structures by comparing its diagnostic image quality with that of 64-multidetector row CT. Sagittal slices of a tooth-bearing segment of the maxilla of a commercially purchased dog skull embedded in methyl methacrylate were obtained along a line parallel with the dental arch using a commercial histology diamond saw. The slice of tooth-bearing bone that best depicted the dentoalveolar structures was chosen and photographed. The maxilla segment was imaged with cone beam CT and 64-multidetector row CT. Four blinded evaluators compared the cone beam CT and 64-multidetector row CT images and image quality was scored as it related to the anatomy of dentoalveolar structures. Trabecular bone, enamel, dentin, pulp cavity, periodontal ligament space, and lamina dura were scored. In addition, a score depicting the evaluators overall impression of the image was recorded. Images acquired with cone beam CT were found to be significantly superior in image quality to images acquired with 64-multidetector row CT overall, and in all scored categories. In our study setting, cone beam CT was found to be a valid and clinically superior imaging modality for the canine maxillary dentoalveolar structures when compared to 64-multidetector row CT. PMID:26415384

  1. Comparison of the Diagnostic Image Quality of the Canine Maxillary Dentoalveolar Structures Obtained by Cone Beam Computed Tomography and 64-Multidetector Row Computed Tomography.

    Science.gov (United States)

    Soukup, Jason W; Drees, Randi; Koenig, Lisa J; Snyder, Christopher J; Hetzel, Scott; Miles, Chanda R; Schwarz, Tobias

    2015-01-01

    The objective of this blinded study was to validate the use of cone beam computed tomography (C) for imaging of the canine maxillary dentoalveolar structures by comparing its diagnostic image quality with that of 64-multidetector row CT Sagittal slices of a tooth-bearing segment of the maxilla of a commercially purchased dog skull embedded in methylmethacrylate were obtained along a line parallel with the dental arch using a commercial histology diamond saw. The slice of tooth-bearing bone that best depicted the dentoalveolar structures was chosen and photographed. The maxillary segment was imaged with cone beam CT and 64-multidetector row CT. Four blinded evaluators compared the cone beam CT and 64-multidetector row CT images and image quality was scored as it related to the anatomy of dentoalveolar structures. Trabecular bone, enamel, dentin, pulp cavity, periodontal ligament space, and lamina dura were scored In addition, a score depicting the evaluators overall impression of the image was recorded. Images acquired with cone beam CT were found to be significantly superior in image quality to images acquired with 64-multidetector row CT overall, and in all scored categories. In our study setting cone beam CT was found to be a valid and clinically superior imaging modality for the canine maxillary dentoalveolar structures when compared to 64-multidetector row CT.

  2. 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.

  3. Influence of cone-beam computed tomography milliamperage settings on image quality of the mandibular third molar region

    International Nuclear Information System (INIS)

    Neves, Frederico Sampaio; Souza, Thais de Camargo; De-Azevedo-Vaz, Sergio Lins; Boscolo, Frab Norberto; Campos, Paulo Sergio Flores

    2014-01-01

    The objective of this study was to assess the image quality of the mandibular third molar region using different milliamperage (mA) settings of cone-beam computed tomography. Twelve dry mandibles with impacted third molars were scanned with a Kodak 9000 unit (Kodak Dental Systems, Carestream Health, Rochester, NY, USA) using different mA settings (2, 4, 6.3, 8, 10, 12, and 15 mA). Two oral radiologists evaluated the images. They classified the tooth root, periodontal space, lamina dura, trabecular bone, mandibular canal, and overall image quality as excellent, good, poor, or inadequate for diagnosis. Statistical analyses were performed by one-way ANOVA with a post hoc Tukey test to investigate the influence of the mA settings in the image quality of the structures analyzed. The significance level was set at 5%. The 15 and 12 mA settings provided the highest mean values for all the evaluated criteria, with significant differences from the values for the other mA settings. The 10, 8, and 6.3 mA settings showed no significant differences in relation to tooth root and periodontal space. For the other evaluated criteria, no significant differences were observed for the 10 and 8 mA settings. The 4 and 2 mA settings gave the lowest mean values. The best low-dose protocol with good image quality was the 10 mA setting. Lower dose protocols with 8 and 6.3 mA settings can also be used for these purposes, but caution is necessary because of increased image noise. (author)

  4. 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.

  5. 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)

  6. Simulations of far-field optical beam quality influenced by the thermal distortion of the secondary mirror for high-power laser system

    Science.gov (United States)

    Guo, Ruhai; Chen, Ning; Zhuang, Xinyu; Wang, Bing

    2015-02-01

    In order to research the influence on the beam quality due to thermal deformation of the secondary mirror in the high power laser system, the theoretical simulation study is performed. Firstly, three typical laser power 10kW, 50kW and 100kW with the wavelength 1.064μm are selected to analyze thermal deformation of mirror through the finite element analyze of thermodynamics instantaneous method. Then the wavefront aberration can be calculated by ray-tracing theory. Finally, focus spot radius,beam quality (BQ) of far-filed beam can be calculated and comparably analyzed by Fresnel diffraction integration. The simulation results show that with the increasing laser power, the optical aberration of beam director gets worse, the far-field optical beam quality decrease, which makes the laser focus spot broadening and the peak optical intensity of center decreasing dramatically. Comparing the clamping ring and the three-point clamping, the former is better than the latter because the former only induces the rotation symmetric deformation and the latter introduces additional astigmatism. The far-field optical beam quality can be improved partly by simply adjusting the distance between the main mirror and the secondary mirror. But the far-field power density is still the one tenth as that without the heat distortion of secondary mirror. These results can also provide the reference to the thermal aberration analyze for high power laser system and can be applied to the field of laser communication system and laser weapon etc.

  7. 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.

  8. 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

  9. A comparative evaluation of Cone Beam Computed Tomography (CBCT) and Multi-Slice CT (MSCT) Part I. On subjective image quality

    NARCIS (Netherlands)

    Liang, X.; Jacobs, R.; Hassan, B.; Li, L.M.; Pauwels, R.; Corpas, L.; Souza, P.C.; Martens, W.; Alonso, A.; Lambrichts, I.

    2010-01-01

    Aims: To compare image quality and visibility of anatomical structures in the mandible between five Cone Beam Computed Tomography (CBCT) scanners and one Multi-Slice CT (MSCT) system. Materials and methods: One dry mandible was scanned with five CBCT scanners (Accuitomo 3D, i-CAT, NewTom 3G,

  10. Influencing Factors for Sleep Quality Among Shift-working Nurses: A Cross-Sectional Study in China Using 3-factor Pittsburgh Sleep Quality Index.

    Science.gov (United States)

    Zhang, Li; Sun, Dong-Mei; Li, Chang-Bing; Tao, Min-Fang

    2016-12-01

    The aim of this study was to identify influencing factors for sleep quality among shift-working nurses based on a three-factor scoring model that included sleep efficacy, sleep quality and daily dysfunction. A cross-sectional survey of 513 nurses in a hospital in Shanghai, China, was conducted using a self-reported questionnaire. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI). Data were analyzed based on the three-factor PSQI model: Factor 1, sleep efficacy; Factor 2, sleep quality; Factor 3, daily disturbances. After adjusting for age, marital status, and having children, multivariate logistic regression analysis showed that participants who had previous shift work experience which was at least 6 months ago, or were currently performing shift work were significantly more likely to have poor sleep quality (PSQI > 5) than those who had never done shift work (adjusted odds ratios of 3.943 and 3.975, respectively, both p sleep quality. An appropriate arrangement and intervention strategies are needed in Chinese hospitals in order to improve sleep quality among shift-working nurses. Copyright © 2016. Published by Elsevier B.V.

  11. Quality Factor for the Hadronic Calorimeter in High Luminosity Conditions

    CERN Document Server

    Seixas, Jose; The ATLAS collaboration; Manhaes de Andrade Filho, Luciano; Sotto-Maior-Peralva, Bernardo

    2015-01-01

    The Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of ATLAS experiment and has about 10,000 eletronic channels. An Optimal Filter (OF) has been used to estimate the energy sampled by the calorimeter and applies a Quality Factor (QF) for signal acceptance. An approach using Matched Filter (MF) has also been pursued. In order to cope with the luminosity rising foreseen for LHC operation upgrade, different algorithms have been developed. Currently, the OF measure for signal acceptance is implemented through a chi-square test. At a low luminosity scenario, such QF measure has been used as a way to describe how the acquired signal is compatible to the pulse shape pattern. However, at high-luminosity conditions, due to pile up, this QF acceptance is no longer possible when OF is employed, and the QF becomes a measure to indicate whether the reconstructed signal suffers or not from pile up. Methods are being developed in order to recover the superposed information, and the QF may be us...

  12. 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.

  13. 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)

    Østerås, Bjørn Helge; Skaane, Per; Gullien, Randi; Martinsen, Anne Catrine Trægde

    2018-01-25

    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.

  14. Quality response of 'Bing' and 'Rainier' sweet cherries to low rose electron beam irradiation

    International Nuclear Information System (INIS)

    Drake, S.R.; Neven, L.G.

    1997-01-01

    'Bing' and 'Rainier' sweet cherries were irradiated at doses of 0.00, 0.15, 0.30, 0.60 and 0.90 kGy using a linear accelerator. Cherries were evaluated for quality immediately after treatment and again after 14 days storage at 1C. No variation in soluble solids, titratable acidity or flavor were noted at any of the irradiation doses. Defects were increased for 'Rainier' cherries at irradiation doses above 0.60 kGy, but no change in defects of 'Bing' cherries were present regardless of irradiation doses. Objective color of 'Bing' cherries was lighter with more red at irradiation doses greater than 0.30 kGy, but this change in color was not evident visually. Objective color of 'Rainier' cherries was reduced at irradiation doses of 0.60 kGy and greater. This reduction in 'Rainier' red color was evident visually at an irradiation dose of 0.90 kGy. No change in 'Bing' green stem color was evident, but 'Rainier' stem color improved at irradiation doses above 0.60 kGy. Firmness of both 'Bing' and 'Rainier' cherries was reduced at irradiation doses of 0.60 kGy and greater. By using the linear accelerator at doses of 0.60 kGy or less, 'Ring' and 'Rainier' cherries can be irradiated with no major quality loss to meet quarantine requirements

  15. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

    Science.gov (United States)

    Abu Anas, Emran Mohammad; Kim, Jae Gon; Lee, Soo Yeol; Kamrul Hasan, Md

    2011-10-01

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

  16. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging

    International Nuclear Information System (INIS)

    Anas, Emran Mohammad Abu; Hasan, Md Kamrul; Kim, Jae Gon; Lee, Soo Yeol

    2011-01-01

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

  17. Effect of absorbed pump power on the quality of output beam from ...

    Indian Academy of Sciences (India)

    The contribution to the phase shift from thermal stress induced birefringence, i.e., the term containing εij in eq. (1) is small and can be neglected [3]. For monolithic laser the factor. (n-1) in eq. (1) has to be replaced by n because the cavity mirrors are directly deposited on the crystal surface and there is no crystal–air interface ...

  18. The level and influencing factors of quality of life in patients with brachial plexus injury

    Directory of Open Access Journals (Sweden)

    Jie Shen

    2014-06-01

    Conclusions: A brachial plexus injury significantly compromises an individual's quality of life. Multiple factors influence this quality, which should be targeted to augment the physical and psychological care provided.

  19. Quality of Life and Its Factors in Korean Elderly With Mild Cognitive Impairment.

    Science.gov (United States)

    Kang, Younhee; Lee, Eliza

    2017-06-01

    Based on the secondary data analysis, this study aimed to identify quality of life and factors that affect quality of life among Korean elderly with mild cognitive impairment. Demographic characteristics, physical factors, and psychosocial factors as well as quality of life of the elderly with mild cognitive impairment were comprehensively measured. The research subjects consisted of 348 home-resident elderly and their quality of life scores were relatively high at 29.86. Their quality of life varied according to education and gender, and instrumental activities of daily living (actual, latent), somatic symptoms, sleep quality, depression, and social support affected their quality of life. Depression and social support were predictors of quality of life. The most powerful predictor was depression (β = -.583, p quality of life among elderly with mild cognitive impairment, nursing interventions to alleviate depression and to enhance social support from family, friends, and relevant neighbors are needed.

  20. [Quality of realgar and its influencing factors based on toxicity].

    Science.gov (United States)

    Jiang, La; Xu, Huan-Hua; Jiang, Zhen-Hong; Yang, Shi-Han; Shi, Qiao-Li; Ma, Zeng-Chun; Gao, Yue; Chen, Zhi-Wu

    2017-12-01

    The results of a toxicity analysis showed differences from those of the existing experimental data. Therefore, HPLC-ICP-MS was used to analyze the soluble arsenic content at different valences in realgar prepared with water grind processing, which were collected from 3 companies. The results showed that the free arsenic of the 3 companies did not exceed the limit of Chinese Pharmacopoeia. However, if the free arsenic was calculated based on the total value of As(Ⅲ) + As(Ⅴ), free arsenic of 1 company exceeded the limit of Chinese Pharmacopoeia. The method of determining free arsenic in Chinese Pharmacopoeia. was ancient Cai's arsenic detection method, which had a certain limitation and failed to effectively avoid the toxicity of remaining arsenics except for trivalent arsenic. Then, we examined the effects of water and temperature on the content and form of soluble arsenic in realgar. The results showed that the content of soluble arsenic increased with the rise of water content, and the form of soluble arsenic did not change, there were only As (Ⅲ) and As (Ⅴ); With the simple temperature factor, there was an increasing trend in the content of soluble arsenic in the samples, the maximum increment was As (Ⅲ) 2.489 mg•g⁻¹ and As (Ⅴ) 0.546 mg•g⁻¹; When water and temperature played an synergistic effect, the increase of soluble arsenic in the samples significantly changed, the maximum increment was As (Ⅲ) 23.690 mg•g⁻¹, As (Ⅴ) 0.468 mg•g⁻¹, respectively. Through comprehensive analysis, we believed that the quality of realgar was susceptible to water content and temperature. Both of the single effect of water content and the synergistic effect of water and temperature can significantly change the content of soluble arsenic in realgar, and the water content was a high-risk factor. In the current Chinese Pharmacopoeia 2015 version, the free arsenic detection method had limitations, hence new techniques shall be introduced; At the same

  1. Factors Affecting Quality of Laboratory Services in Public and Private Health Facilities in Addis Ababa, Ethiopia

    OpenAIRE

    Mesfin, Eyob Abera; Taye, Binyam; Belay, Getachew; Ashenafi, Aytenew; Girma, Veronica

    2017-01-01

    Background Quality laboratory service is an essential component of health care system but in Sub-Saharan Africa such as Ethiopia, laboratories quality system remains weak due to several factors and it needs more attention to strengthen its capacity and quality system. Methodology A cross sectional study was conducted using a questionnaire to assess factors affecting the quality of laboratory service at private and public health institutions in Addis Ababa. Results A total of 213 laboratory pr...

  2. Controllable high-quality electron beam generation by phase slippage effect in layered targets

    Czech Academy of Sciences Publication Activity Database

    Yu, Q.; Gu, Yanjun; Li, X.F.; Huang, S.; Zhang, F.; Kong, O.; Ma, Y.Y.; Kawata, S.

    2014-01-01

    Roč. 21, č. 11 (2014), "113106-1"-"113106-6" ISSN 1070-664X R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : laser * plasma * electrons Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.142, year: 2014

  3. 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.

  4. 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.

  5. Some factors governing the water quality of microtidal estuaries in ...

    African Journals Online (AJOL)

    The role of coastal geomorphology and Man-made alterations, including reduced river flow through dam construction, determines, at least in part, the water quality of South African microtidal estuaries. To offer increased understanding of the manner in which these features may modify water quality, a short description of the ...

  6. Factors influencing quality of leadership in public higher institutions ...

    African Journals Online (AJOL)

    The study investigates the quality of leadership in higher institutions of learning in Ghana using data from three (3) public universities. Using a mixed method, the study employed both exploratory and causal design to investigate the dimensions of Quality of Leadership from the Ghanaian perspective. The paper proceeded ...

  7. 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…

  8. Some Factors Affecting the Quality of Meat from Ruminants and ...

    African Journals Online (AJOL)

    Further, means for obtaining quality meat under Tanzanian conditions are pointed out. Meat quality encompasses various attributes ranging from carcass composition to health and production-related issues including animal welfare. These attributes can be manipulated to man's advantage at different stages of obtaining ...

  9. Reclaiming Quality in Higher Education: A Human Factor Approach

    Science.gov (United States)

    Cheng, Ming

    2017-01-01

    Interest in quality is well established within higher education. This paper will critically review the most commonly used definitions of quality: fitness for purpose and value for money. It will point out that these two definitions are important but they ignore the emancipatory power of higher education and the development needs of academics and…

  10. 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.

  11. 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…

  12. 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

  13. Determination of output factor for 6 MV small photon beam: comparison between Monte Carlo simulation technique and microDiamond detector

    International Nuclear Information System (INIS)

    Krongkietlearts, K; Tangboonduangjit, P; Paisangittisakul, N

    2016-01-01

    In order to improve the life's quality for a cancer patient, the radiation techniques are constantly evolving. Especially, the two modern techniques which are intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are quite promising. They comprise of many small beam sizes (beamlets) with various intensities to achieve the intended radiation dose to the tumor and minimal dose to the nearby normal tissue. The study investigates whether the microDiamond detector (PTW manufacturer), a synthetic single crystal diamond detector, is suitable for small field output factor measurement. The results were compared with those measured by the stereotactic field detector (SFD) and the Monte Carlo simulation (EGSnrc/BEAMnrc/DOSXYZ). The calibration of Monte Carlo simulation was done using the percentage depth dose and dose profile measured by the photon field detector (PFD) of the 10×10 cm 2 field size with 100 cm SSD. Comparison of the values obtained from the calculations and measurements are consistent, no more than 1% difference. The output factors obtained from the microDiamond detector have been compared with those of SFD and Monte Carlo simulation, the results demonstrate the percentage difference of less than 2%. (paper)

  14. Long-Term Quality of Life Outcome After Proton Beam Monotherapy for Localized Prostate Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Coen, John J., E-mail: jcoen@partners.org [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Paly, Jonathan J.; Niemierko, Andrzej; Weyman, Elizabeth [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Rodrigues, Anita [Department of Medical Oncology, Massachusetts General Hospital, Boston, MA (United States); Shipley, William U.; Zietman, Anthony L. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States); Talcott, James A. [Department of Medical Oncology, Massachusetts General Hospital, Boston, MA (United States)

    2012-02-01

    Objectives: High-dose external radiation for localized prostate cancer results in favorable clinical outcomes and low toxicity rates. Here, we report long-term quality of life (QOL) outcome for men treated with conformal protons. Methods: QOL questionnaires were sent at specified intervals to 95 men who received proton radiation. Of these, 87 men reported 3- and/or 12-month outcomes, whereas 73 also reported long-term outcomes (minimum 2 years). Symptom scores were calculated at baseline, 3 months, 12 months, and long-term follow-up. Generalized estimating equation models were constructed to assess longitudinal outcomes while accounting for correlation among repeated measures in an individual patient. Men were stratified into functional groups from their baseline questionnaires (normal, intermediate, or poor function) for each symptom domain. Long-term QOL changes were assessed overall and within functional groups using the Wilcoxon signed-rank test. Results: Statistically significant changes in all four symptom scores were observed in the longitudinal analysis. For the 73 men reporting long-term outcomes, there were significant change scores for incontinence (ID), bowel (BD) and sexual dysfunction (SD), but not obstructive/irritative voiding dysfunction (OID). When stratified by baseline functional category, only men with normal function had increased scores for ID and BD. For SD, there were significant changes in men with both normal and intermediate function, but not poor function. Conclusions: Patient reported outcomes are sensitive indicators of treatment-related morbidity. These results quantitate the long-term consequences of proton monotherapy for prostate cancer. Analysis by baseline functional category provides an individualized prediction of long-term QOL scores. High dose proton radiation was associated with small increases in bowel dysfunction and incontinence, with more pronounced changes in sexual dysfunction.

  15. Long-Term Quality of Life Outcome After Proton Beam Monotherapy for Localized Prostate Cancer

    International Nuclear Information System (INIS)

    Coen, John J.; Paly, Jonathan J.; Niemierko, Andrzej; Weyman, Elizabeth; Rodrigues, Anita; Shipley, William U.; Zietman, Anthony L.; Talcott, James A.

    2012-01-01

    Objectives: High-dose external radiation for localized prostate cancer results in favorable clinical outcomes and low toxicity rates. Here, we report long-term quality of life (QOL) outcome for men treated with conformal protons. Methods: QOL questionnaires were sent at specified intervals to 95 men who received proton radiation. Of these, 87 men reported 3- and/or 12-month outcomes, whereas 73 also reported long-term outcomes (minimum 2 years). Symptom scores were calculated at baseline, 3 months, 12 months, and long-term follow-up. Generalized estimating equation models were constructed to assess longitudinal outcomes while accounting for correlation among repeated measures in an individual patient. Men were stratified into functional groups from their baseline questionnaires (normal, intermediate, or poor function) for each symptom domain. Long-term QOL changes were assessed overall and within functional groups using the Wilcoxon signed-rank test. Results: Statistically significant changes in all four symptom scores were observed in the longitudinal analysis. For the 73 men reporting long-term outcomes, there were significant change scores for incontinence (ID), bowel (BD) and sexual dysfunction (SD), but not obstructive/irritative voiding dysfunction (OID). When stratified by baseline functional category, only men with normal function had increased scores for ID and BD. For SD, there were significant changes in men with both normal and intermediate function, but not poor function. Conclusions: Patient reported outcomes are sensitive indicators of treatment-related morbidity. These results quantitate the long-term consequences of proton monotherapy for prostate cancer. Analysis by baseline functional category provides an individualized prediction of long-term QOL scores. High dose proton radiation was associated with small increases in bowel dysfunction and incontinence, with more pronounced changes in sexual dysfunction.

  16. Measurement of backscatter factor for kilovoltage x-ray beam using ionization chamber and Gafchromic XR-QA2 film

    Science.gov (United States)

    Shukor, N. S. Ab; Asri, N. H. Mohd; Syed Jaafar, S. M. F.; Rosnan, M. S.; Aziz, S. A. Abdul

    2018-01-01

    Backscatter factor (BSF) is an important parameter in the determination of surface dose for kilovoltage X-ray beam. The purpose of this study was to measure the BSF for kilovoltage diagnostic X-ray beam, and compare the measured BSF between Gafchromic XR-QA2 film and shadow free (SFD) ionization chamber (IC). The parameters that may affect the BSF, such as tube voltage (kVp) and field size, were also studied. The results were in good agreement with the TRS 457, with deviation of less than 12 %. Based on the film study, the BSF obtained from the film measurement were found to be lower than that of the IC, with average difference of 26 %. It was also found that smaller field size resulted in lower effective energy, and the amount of photons which scattered back onto the surface were also smaller. This study demonstrated that the Gafchromic XR-QA2 film was not suitable for the application of small field size.

  17. Effects of electron beam irradiation on chemical composition, antinutritional factors, ruminal degradation and in vitro protein digestibility of canola meal

    Energy Technology Data Exchange (ETDEWEB)

    Taghinejad-Roudbaneh, M., E-mail: mtaghinejad@iaut.ac.i [Department of Animal Science, Faculty of Agriculture, Islamic Azad University, Tabriz Branch, P.O. Box 51589, Tabriz (Iran, Islamic Republic of); Ebrahimi, S.R. [Department of Animal Science, Faculty of Agriculture, Shahr-e-Qods Branch, Islamic Azad University, P.O. Box 37515-374, Shahr-e-Qods (Iran, Islamic Republic of); Azizi, S. [Department of Clinical Sciences, Faculty of Veterinary Medicine, Urmia University, P.O. Box 57155-1177, Urmia (Iran, Islamic Republic of); Shawrang, P. [Nuclear Science and Technology Research Institute, Agricultural, Medical and Industrial Research School, Atomic Energy Organization of Iran, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of)

    2010-12-15

    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 (P<0.01). From in situ results, irradiation of canola meal at doses of 45 kGy decreased (P<0.05) the effective degradibility of crude protein (CP) by 14%, compared with an untreated sample. In vitro CP digestibility of EB-irradiated canola meal at doses of 15 and 30 kGy was improved (P<0.05). Electrophoresis results showed that napin and cruciferin sub-units of 30 and 45 kGy EB-irradiated canola meal were more resistant to degradation, compared with an untreated sample. Electron beam irradiation was effective in protecting CP from ruminal degradation and reducing antinutritional factors of irradiated canola meal.

  18. Ion recombination and polarity correction factors for a plane-parallel ionization chamber in a proton scanning beam.

    Science.gov (United States)

    Liszka, Małgorzata; Stolarczyk, Liliana; Kłodowska, Magdalena; Kozera, Anna; Krzempek, Dawid; Mojżeszek, Natalia; Pędracka, Anna; Waligórski, Michael Patrick Russell; Olko, Paweł

    2018-01-01

    To evaluate the effect on charge collection in the ionization chamber (IC) in proton pencil beam scanning (PBS), where the local dose rate may exceed the dose rates encountered in conventional MV therapy by up to three orders of magnitude. We measured values of the ion recombination (k s ) and polarity (k pol ) correction factors in water, for a plane-parallel Markus TM23343 IC, using the cyclotron-based Proteus-235 therapy system with an active proton PBS of energies 30-230 MeV. Values of k s were determined from extrapolation of the saturation curve and the Two-Voltage Method (TVM), for planar fields. We compared our experimental results with those obtained from theoretical calculations. The PBS dose rates were estimated by combining direct IC measurements with results of simulations performed using the FLUKA MC code. Values of k s were also determined by the TVM for uniformly irradiated volumes over different ranges and modulation depths of the proton PBS, with or without range shifter. By measuring charge collection efficiency versus applied IC voltage, we confirmed that, with respect to ion recombination, our proton PBS represents a continuous beam. For a given chamber parameter, e.g., nominal voltage, the value of k s depends on the energy and the dose rate of the proton PBS, reaching c. 0.5% for the TVM, at the dose rate of 13.4 Gy/s. For uniformly irradiated regular volumes, the k s value was significantly smaller, within 0.2% or 0.3% for irradiations with or without range shifter, respectively. Within measurement uncertainty, the average value of k pol , for the Markus TM23343 IC, was close to unity over the whole investigated range of clinical proton beam energies. While no polarity effect was observed for the Markus TM23343 IC in our pencil scanning proton beam system, the effect of volume recombination cannot be ignored. © 2017 American Association of Physicists in Medicine.

  19. 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

  20. Calculation of computed tomography dose index to effective dose conversion factors based on measurement of the dose profile along the fan shaped beam.

    Science.gov (United States)

    Jansen, J T; Geleijns, J; Zweers, D; Schultz, F W; Zoetelief, J

    1996-01-01

    The variation in computed tomography dose index (CTDI) to effective dose conversion factors between different types of CT scanner is large (i.e. a factor of about 2 due to differences in beam shaping filters). Consequently, scanner specific conversion factors have to be applied. For some types of scanner, however, detailed information on the construction of beam shaping filters is not provided by the manufacturers. It is of interest to investigate the use of measured dose profiles for the calculation of conversion factors. Based upon measured dose profiles, two appropriate photon spectra selected on the basis of measured half value layers, gender specific adult phantoms Adam and Eva, and the Monte Carlo neutron and photon radiation transport code (MCNP), organ and effective dose conversion factors are calculated. To validate the method, a comparison is made between results for measured and calculated beam profiles for a Philips Tomoscan 350. The results in terms of effective dose per slice per unit of CTDI are compared with published data. Relative difference in conversion factors per slice averaged over all slices used for the calculations is 13 +/- 4% between the two spectra, 10.2 +/- 0.2% between measured and calculated beam profiles and 50 +/- 191% between the phantoms of different gender. The relative difference between the averaged results for the Adam and Eva phantoms and published results for a hermaphrodite phantom is on average equal to or less than 15 +/- 13%, depending on the spectrum and beam profile used, although larger differences can occur for specific slices. It is concluded that CTDI to effective dose conversion factors can be derived on the basis of measured beam profiles.

  1. 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?...

  2. 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.

  3. SU-F-T-232: Monthly Quality Assurance in External Beam Radiation Therapy Using a Single System

    Energy Technology Data Exchange (ETDEWEB)

    Ding, K [Department of Radiation Oncology, Johns Hopkins University, Baltimore, MD (United States); Ji, T [Department of Radiation Oncology, Johns Hopkins University, Baltimore, MD (United States); Department of Radiation Oncology, The First Hospital, China Medical University, Shenyang, Liaoning (China); Iordachita, I [Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD (United States); Velarde, E; Hyatt, J; Wong, J

    2016-06-15

    Purpose: Monthly quality assurance (QA) is time consuming for external beam radiation therapy, taking as long as 6–8 hours for each machine. It is due to the use and setup of multiple devices for different QA procedures. We have developed a single system with rotational capability for the measurement of both optical light and radiation which significantly reduces the time spent on Monthly QA. Methods: A single system using mirrors, a phosphor screen and a CCD camera is housed on a cylindrical motor so that it can rotate 360 degrees. For monthly QA, the system is placed on the patient couch of the medical accelerator with the plane of the phosphor screen at isocenter for all measurements. For optical QA such as optical distance indicator, room laser and light field, the optical image is collected directly with the camera. For radiation QA such as beam profile, MLC speed, picket-fence test, collimator rotation, table rotation and gantry rotation, a brass build-up plate is attached to the top of the phosphor screen. Two brass plates with islands of different thickness were designed for photon energy and electron energy constancy checks. Flex map, distortion map and uniformity map were developed to calibrate the motor bearing, camera/lens distortion, and the phosphor screen’s measured response across the field. Results: Following the TG142 guidelines for monthly QA with our system, the overall run time is reduced from 6–8 hours to 1.5 hours. Our system’s rotating design allows for quick testing of the gantry radiation isocenter test that is also independent of the sag of the gantry and the EPID. Conclusion: Our system significantly shortens the time needed for monthly QA by unifying the tests with a single system. Future work will be focused on extending the technology to Brachytherapy, IMRT and proton therapy QAs. This work is funded in part by a sponsor research grant from JPLC who owns the Raven technology. John Wong is a co-founder of JPLC.

  4. Factors affecting the possibility to detect buccal bone condition around dental implants using cone beam computed tomography

    DEFF Research Database (Denmark)

    Liedke, Gabriela S; Spin-Neto, Rubens; da Silveira, Heloisa E D

    2016-01-01

    OBJECTIVES: To evaluate factors with impact on the conspicuity (possibility to detect) of the buccal bone condition around dental implants in cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS: Titanium (Ti) or zirconia (Zr) implants and abutments were inserted into 40 bone blocks...... in a way to obtain variable buccal bone thicknesses. Three combinations regarding the implant-abutment metal (TiTi, TiZr, or ZrZr) and the number of implants (one, two, or three) were assessed. Two CBCT units (Scanora 3D - Sc and Cranex 3D - Cr) and two voxel resolutions (0.2 and 0.13 mm) were used....... Reconstructed sagittal images (2.0 and 5.0 mm thickness) were evaluated by three examiners, using a dichotomous scale when assessing the condition of the buccal bone around the implants. A multivariate logistic regression was performed using examiners' detection of the buccal bone condition as the dependent...

  5. Electron beam and mechanical lithographies as enabling factors for organic-based device fabrication

    International Nuclear Information System (INIS)

    Visconti, P.; Pisignano, D.; Della Torre, A.; Persano, L.; Maruccio, G.; Biasco, A.; Cingolani, R.; Rinaldi, R.

    2005-01-01

    Organic-based photonics and molecular electronics are attracting an increasing interest in modern science. The realization of high-resolution master structures by electron beam lithography (EBL) and their transfer to different organic functional materials by mechanical lithographies allow to fully exploit the wide flexibility of molecular systems for opto- and nanoelectronic devices. Planar nanojunctions, consisting of two metallic electrodes separated by an insulating medium, permit to test the molecular conduction properties. Since the typical size of a biomolecule is of the order of a few nanometer, hybrid molecular electronic (HME) devices need metallic electrodes separated by a nanometer-scale channel. Conversely, photonic applications often require 100 nm to 1 μm features on large areas. In this work, we report on the fabrication of both large-area periodic master structures with resolution down to 200 nm, and planar metallic electrodes with sub-10 nm separation obtained by EBL followed by metal electroplating deposition. The fabricated 3-terminal bio-nanodevices show a transistor-like behaviour with a maximum voltage gain of 0.76. Moreover, we developed a number of mechanical patterning methods, including soft hot embossing, rapid prototyping, sub-micrometer fluidics, high- and room-temperature nanoimprinting, to fabricate planar nanostructures on both biomolecular and organic materials. These allowed us a high-fidelity pattern transfer up to 100-nm scale resolution, without reducing the emission yields of light-emitting organics, thus opening the way to the one-step realization of organic-based confined optoelectronic devices

  6. Scaling up and controlling beam quality of flowing-gas diode pumped potassium laser with different pumping geometries: 3D CFD modeling

    Science.gov (United States)

    Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Barmashenko, Boris D.; Rosenwaks, Salman

    2017-10-01

    Comprehensive analysis of the performance and beam quality of subsonic flowing-gas K diode-pumped alkali lasers (DPALs) with different pumping geometries, using 3D computational fluid dynamics model, is reported. The model is first applied to a K DPAL with transverse pumping and parameters similar to those of the 1.5 kW K DPAL [Pitz et al, Proc. SPIE 9729, 972902 (2016)] and the calculated results are in satisfactory agreement with the measurements. To study the possibility of scaling up the K DPAL the model is then applied to 100-kW class device with transverse and end pumping geometry. Dependence of the output power on the flow velocity and the pumping geometry is studied. Comparison between end and transverse pumping schemes shows that the output power is almost unaffected by the pumping geometry. However, the spatial intensity distribution of the output laser beam depends on the pumping geometry: it is uniform for the end pumping, whereas for the transverse pumping it is strongly non-uniform at high gas temperature (corresponding to large density of K atoms), becoming more uniform with temperature reduction. The model is applied to evaluation of the beam quality of flowing-gas K DPALs which strongly depends on the refractive index distribution in the gain medium. The beam divergence and the width of the intensity profile in the far field for the end pumping appear to be much smaller than for the transverse pumping. Wave front corrections of the transversely pumped device using cylindrical lens results in substantial reduction of the laser beam divergence and improvement of its quality which becomes comparable with that of the end pumped laser.

  7. Development and clinical translation of a cone-beam CT scanner for high-quality imaging of intracranial hemorrhage

    Science.gov (United States)

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

    2017-03-01

    Purpose: Prompt, reliable detection of intracranial hemorrhage (ICH) is essential for treatment of stroke and traumatic brain injury, and would benefit from availability of imaging directly at the point-of-care. This work reports the performance evaluation of a clinical prototype of a cone-beam CT (CBCT) system for ICH imaging and introduces novel algorithms for model-based reconstruction with compensation for data truncation and patient motion. Methods: The tradeoffs in dose and image quality were investigated as a function of analytical (FBP) and model-based iterative reconstruction (PWLS) algorithm parameters using phantoms with ICH-mimicking inserts. Image quality in clinical applications was evaluated in a human cadaver imaged with simulated ICH. Objects outside of the field of view (FOV), such as the head-holder, were found to introduce challenging truncation artifacts in PWLS that were mitigated with a novel multi-resolution reconstruction strategy. Following phantom and cadaver studies, the scanner was translated to a clinical pilot study. Initial clinical experience indicates the presence of motion in some patient scans, and an image-based motion estimation method that does not require fiducial tracking or prior patient information was implemented and evaluated. Results: The weighted CTDI for a nominal scan technique was 22.8 mGy. The high-resolution FBP reconstruction protocol achieved < 0.9 mm full width at half maximum (FWHM) of the point spread function (PSF). The PWLS soft-tissue reconstruction showed <1.2 mm PSF FWHM and lower noise than FBP at the same resolution. Effects of truncation in PWLS were mitigated with the multi-resolution approach, resulting in 60% reduction in root mean squared error compared to conventional PWLS. Cadaver images showed clear visualization of anatomical landmarks (ventricles and sulci), and ICH was conspicuous. The motion compensation method was shown in clinical studies to restore visibility of fine bone structures

  8. TH-E-17A-09: High Quality and Artifact-Free 4D Cone Beam CT and Its Application in Adaptive Treatment Planning

    Energy Technology Data Exchange (ETDEWEB)

    Niu, K; Li, K; Smilowitz, J; Chen, G [University of Wisconsin, Madison, WI (United States)

    2014-06-15

    Purpose: To develop a high quality 4D cone beam CT (4DCBCT) method that is immune to patient/couch truncations and to investigate its application in adaptive replanning of lung XRT. Methods: In this study, IRB-approved human subject CBCT data was acquired using a Varian on-board imager with 1 minute rotation time. The acquired projection data was retrospectively sorted into 20 respiratory phase bins, from which 4DCBCT images with high SNR and high temporal resolution were generated using Prior Image Constrained Compressed Sensing (PICCS). Couch and patient truncations generate strong data inconsistency in the projection data and artifacts in the 4DCBCT image. They were addressed using an adaptive PICCS method. The artifact-free PICCS-4DCBCT images were used to generate adaptive treatment plans for the same patient at the 10th (day 21) and 30th (day 47) fractions. Dosimetric impacts with and without PICCS- 4DCBCT were evaluated by isodose distributions, DVHs, and other dosimetric factors. Results: The adaptive PICCS-4DCBCT method improves image quality by removing residue truncation artifacts; measured universal image quality increased 37%. The isodose lines and DVHs with PICCS-4DCBCT-based adaptive replanning were significantly more conformal to PTV than without replanning due to changes in patient anatomy caused by progress of the treatment. The mean dose to PTV at the 10th fraction was 63.1Gy with replanning and 64.2Gy without replanning, where the prescribed dose was 60Gy, in 2Gy × 30 fractions. The mean dose to PTV at the 30th fraction was 61.6Gy with replanning and 64.9Gy without replanning. Lung V20 was 37.1%, 41.9% and 43.3% for original plan, 10th fraction plan and 30th fraction plan; with re-planning, Lung V20 was 37.1%, 32%, 27.8%. Conclusion: 4DCBCT imaging using adaptive PICCS is able to generate high quality, artifact-free images that potentially can be used to create replanning for improving radiotherapy of the lung. K Niu, K Li, J Smilowitz: Nothing

  9. TH-E-17A-09: High Quality and Artifact-Free 4D Cone Beam CT and Its Application in Adaptive Treatment Planning

    International Nuclear Information System (INIS)

    Niu, K; Li, K; Smilowitz, J; Chen, G

    2014-01-01

    Purpose: To develop a high quality 4D cone beam CT (4DCBCT) method that is immune to patient/couch truncations and to investigate its application in adaptive replanning of lung XRT. Methods: In this study, IRB-approved human subject CBCT data was acquired using a Varian on-board imager with 1 minute rotation time. The acquired projection data was retrospectively sorted into 20 respiratory phase bins, from which 4DCBCT images with high SNR and high temporal resolution were generated using Prior Image Constrained Compressed Sensing (PICCS). Couch and patient truncations generate strong data inconsistency in the projection data and artifacts in the 4DCBCT image. They were addressed using an adaptive PICCS method. The artifact-free PICCS-4DCBCT images were used to generate adaptive treatment plans for the same patient at the 10th (day 21) and 30th (day 47) fractions. Dosimetric impacts with and without PICCS- 4DCBCT were evaluated by isodose distributions, DVHs, and other dosimetric factors. Results: The adaptive PICCS-4DCBCT method improves image quality by removing residue truncation artifacts; measured universal image quality increased 37%. The isodose lines and DVHs with PICCS-4DCBCT-based adaptive replanning were significantly more conformal to PTV than without replanning due to changes in patient anatomy caused by progress of the treatment. The mean dose to PTV at the 10th fraction was 63.1Gy with replanning and 64.2Gy without replanning, where the prescribed dose was 60Gy, in 2Gy × 30 fractions. The mean dose to PTV at the 30th fraction was 61.6Gy with replanning and 64.9Gy without replanning. Lung V20 was 37.1%, 41.9% and 43.3% for original plan, 10th fraction plan and 30th fraction plan; with re-planning, Lung V20 was 37.1%, 32%, 27.8%. Conclusion: 4DCBCT imaging using adaptive PICCS is able to generate high quality, artifact-free images that potentially can be used to create replanning for improving radiotherapy of the lung. K Niu, K Li, J Smilowitz: Nothing

  10. 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…

  11. 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

  12. The human factors of quality and QA in R D environments

    Energy Technology Data Exchange (ETDEWEB)

    Hill, S.G.

    1990-01-01

    Achieving quality is a human activity. It is therefore important to consider the human in the design, development and evaluation of work processes and environments in an effort to enhance human performance and minimize error. It is also important to allow for individual differences when considering human factors issues. Human Factors is the field of study which can provide information on integrating the human into the system. Human factors and quality are related for the customer of R D work, R D personnel who perform the work, and the quality professional who overviews the process of quality in the work. 18 refs., 1 fig.

  13. [Correlations between wild Polygonatum odoratum quality and main ecological factors].

    Science.gov (United States)

    Bu, Jing; Li, Deng-Wu; Wang, Dong-Mei

    2012-06-01

    By the methods of stepwise regression, principal component analysis, and grey relational grade analysis, this paper studied the correlations between the effective components (polysaccharides and water- and alcohol-soluble substances) contents and antioxidant activity of wild Polygonatum odoratum in different places and the ecological factors. Among the test ecological factors, the mean air temperature in January and in July, mean annual precipitation, frost-free period, and soil pH and total potassium were the main factors affecting the effective component contents of P. odoratum, with a contribution rate of 99.0%. As compared with soil factors, climatic factors made more contribution to the effective component contents. Soil total potassium was the key factor controlling the effective component contents, mean annual precipitation was the main decision factor, and mean air temperature in January was the main limiting factor. The plant polysaccharides and water-soluble substance contents were the key factors affecting the antioxidant activity of P. odoratum, and the capability of P. odoratum in excavating DPPH free radical increased with increasing contents of polysaccharides and water-soluble substances.

  14. 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

  15. Near-diffraction-limited segmented broad area diode laser based on off-axis spectral beam combining

    DEFF Research Database (Denmark)

    Jensen, O.B.; Thestrup Nielsen, Birgitte; Andersen, Peter E.

    2006-01-01

    The beam quality of a 500-mu m-wide broad area diode laser with five active segments has been improved beyond the beam quality of the individual segments. The principle of this new laser system is based on off-axis feedback in combination with spectral beam combining. By using a double......-feedback scheme we are able to improve the beam quality of the laser by a factor of 23 from M-2 = 55 for the free-running diode laser to M-2 = 2.4 for the laser with feedback at a drive current of 2.2 A. The improved M-2 value is a factor of 3.4 below M-2 = 8.2 for a single free-running segment. This is the first...... time that the beam quality of a segmented broad area diode laser has been improved beyond the beam quality of the individual segments....

  16. Sleep quality in women with systemic lupus erythematosus: contributing factors and effects on health-related quality of life.

    Science.gov (United States)

    Mirbagher, Leila; Gholamrezaei, Ali; Hosseini, Naeimeh; Sayed Bonakdar, Zahra

    2016-03-01

    Sleep quality disturbances are common in patients with systemic lupus erythematosus (SLE). We evaluated sleep quality and its contributors in women with SLE. Also we evaluated the effects of sleep quality disturbance on patients' health-related quality of life (HRQoL). Sleep quality was assessed in 77 women with SLE (age 36.5 ± 10.1 years) using the Pittsburgh Sleep Quality Index (PSQI). Disease activity and cumulative disease damage were assessed with standard indices. Patients completed the Hospital Anxiety and Depression Scale and LupusQoL. Univariate and multivariate analyses were performed to find contributors of poor sleep quality and association of sleep quality with HRQoL. Poor sleep quality was present in 44 patients (57.1%). Poor sleepers were older (P = 0.015) and had higher body mass index (P = 0.027) and more severe anxiety (P psychological factors were determinants of sleep quality in our study. Studies with objective sleep measures as well as interventional studies are warranted in this regard. © 2014 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

  17. Efectos de los factores de edificabilidad sobre la productividad laboral de moldajes de vigas en fundaciones The effects of buildability factors on formwork labor productivity of grade beams

    Directory of Open Access Journals (Sweden)

    Abdulaziz M Jarkas

    2010-08-01

    decisiones sobre la eficiencia laboral. Por otro lado, los patrones descritos pueden servir como guía a los administradores de la construcción para una efectiva planificación de actividades y utilización laboral eficiente.Buildability is one of the most important factors affecting labor productivity. Nonetheless, an extensive search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the formwork trade level. Despite the importance of this trade to in situ reinforced concrete material, the influence of buildability factors on formwork labor productivity of major structural elements are yet to be quantified in measurable terms. Grade beams are important structural elements which are primarily used to provide one, or a combination, of the following functions: (1 tie the building foundations to provide the required lateral stiffness at the sub-structural levels; (2 reduce the unsupported free length of columns below grade level; and (3 limit excessive differential settlements of isolated foundations. Therefore, the objective of this research is to investigate and quantify the effects and relative influence of the following buildability factors on formwork labor efficiency of this activity: (a variability of beam sizes; (b beam sizes; and (c number of joints formed at beams intersections. To achieve this objective, a large volume of productivity data was collected and analyzed using the multiple regression method. As a result, the effects and relative influence of the buildability factors investigated are determined. Apart from the variability of beam sizes, the findings show significant effects of these factors on formwork labor productivity, which can be used to provide designers feedback on how well their designs consider the requirements of buildability principles, and the consequences of their decisions on labor efficiency. On the other hand, the depicted patterns may provide guidance to

  18. 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…

  19. Associated Factors and Quality of Care Received among Maternal ...

    African Journals Online (AJOL)

    USER

    Deaths at a Regional Hospital in Ghana: Maternal Death Audit Review. Akosua Owusu-Sarpong. 1. *, Kwame A. Boamah ... measure to ensure the quality of institutional maternal health services in the country, all health facilities .... management of patients prior to referral and insufficient information on the referral letter from.

  20. 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.

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

    African Journals Online (AJOL)

    hope&shola

    2010-12-06

    Dec 6, 2010 ... observed after filleting. It has been suggested that this contamination could be due to biofilms present 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.

  2. Factors Affecting Drinking Water Quality from Source to Home in ...

    African Journals Online (AJOL)

    BACK GROUND: Water becomes contaminated with faecal material due to inadequate protection of the source, unhygienic practices of the community at the source and poor household handling practices. The objective of this study was to identify the risks associated with the protected source, to determine the water quality ...

  3. Factors influencing assessment quality in higher vocational education

    NARCIS (Netherlands)

    Baartman, L.; Gulikers, J.T.M.; Dijkstra, A.

    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

  4. Migration of intraprostatic fiducial markers and its influence on the matching quality in external beam radiation therapy for prostate cancer

    International Nuclear Information System (INIS)

    Delouya, Guila; Carrier, Jean-Francois; Beliveau-Nadeau, Dominic; Donath, David; Taussky, Daniel

    2010-01-01

    Purpose: To assess the influence of fiducial marker (FM) migration on the matching quality in external beam radiation therapy (EBRT) for prostate cancer. Materials and methods: The position of FMs were identified using on-board kV imaging (OBI) and their 3-D position established using an in-house reconstruction algorithm for 31 patients with prostate adenocarcinoma. To carry out the match, the positions were overlaid on the digitally reconstructed radiographs (DRR) generated from the planning CT. The distance between each FM was calculated for seven treatments throughout the EBRT course. Four radiotherapy technologists were asked to independently perform and rate the match from OBI to DRR which was then correlated to the extent of FM migration. Results: All the matches were rated by at least three radiotherapy technologists as 'very easy' ('easy' subgroup) for 24 patients (77%), while the other seven patients had their match rated less than 'very easy' and considered the 'not easy' subgroup. The average daily FM migration was 0.93 ± 0.34 mm for the 'easy' subgroup vs. 1.82 ± 0.75 mm for the latter. An average migration >2 mm was seen in five/seven patients in the 'not easy' subgroup as compared to none in the 'easy' subgroup. There was a trend towards less FM migration and better matching if the planning CT was done later than the day of the FM implant (p = 0.093). Conclusions: FM migration >2 mm predicts for a more difficult matching process; PTV margins might have to be adjusted or the planning CT repeated.

  5. Spatial resolution measurements by Radia diagnostic software with SEDENTEXCT image quality phantom in cone beam CT for dental use.

    Science.gov (United States)

    Watanabe, Hiroshi; Nomura, Yoshikazu; Kuribayashi, Ami; Kurabayashi, Tohru

    2018-02-01

    We aimed to employ the Radia diagnostic software with the safety and efficacy of a new emerging dental X-ray modality (SEDENTEXCT) image quality (IQ) phantom in CT, and to evaluate its validity. The SEDENTEXCT IQ phantom and Radia diagnostic software were employed. The phantom was scanned using one medical full-body CT and two dentomaxillofacial cone beam CTs. The obtained images were imported to the Radia software, and the spatial resolution outputs were evaluated. The oversampling method was employed using our original wire phantom as a reference. The resultant modulation transfer function (MTF) curves were compared. The null hypothesis was that MTF curves generated using both methods would be in agreement. One-way analysis of variance tests were applied to the f50 and f10 values from the MTF curves. The f10 values were subjectively confirmed by observing the line pair modules. The Radia software reported the MTF curves on the xy-plane of the CT scans, but could not return f50 and f10 values on the z-axis. The null hypothesis concerning the reported MTF curves on the xy-plane was rejected. There were significant differences between the results of the Radia software and our reference method, except for f10 values in CS9300. These findings were consistent with our line pair observations. We evaluated the validity of the Radia software with the SEDENTEXCT IQ phantom. The data provided were semi-automatic, albeit with problems and statistically different from our reference. We hope the manufacturer will overcome these limitations.

  6. The effects of TGG crystal length on output power and beam quality of a unidirectional ring Nd:YVO4 laser with and without second harmonic generation

    Science.gov (United States)

    Ahmadi, A.; Avazpour, A.; Nadgaran, H.; Mousavi, M.

    2018-04-01

    The effect of terbium gallium garnet (TGG ) crystal length on 1064 and 532 nm output powers and beam quality of a unidirectional ring Nd:YVO4 laser is investigated. In the case of 1064 nm (without nonlinear crystal), the laser output power without considerating the effect of TGG crystal was computed theoretically. Then three TGG crystals with different lengths were placed in the laser setup one by one. A systematic decrease in output power was observed by increasing the TGG crystal length. The experiment was repeated in the case of 532 nm. It was found that in a 532 nm laser, higher laser efficiency and small beam quality degradation can be achieved by increasing the TGG crystal length leading to a 5.7 W green laser with 27 W pump power. The power stability and beam quality were 0.8% for 30 min and less than 1.3, respectively.

  7. A review of the scientific basis for the quality factor for fast neutrons

    International Nuclear Information System (INIS)

    Myers, D.K.; Johnson, J.R.

    1986-04-01

    Recently, the ICRP has recommended that the quality factor for fast neutrons be increased by a factor of two. They did not give a detailed explanation of the reasons for their recommendations, but indicated that the reasons would be developed as part of a much larger review of the quality factor for all radiations. Since it is AECB's policy to follow ICRP's recommendations unless there is good reason not to do so, and since the changing of the quality factor for neutrons has not been generally accepted by other countries a review of the scientific basis for the neutron quality factor was requested. This report gives results of that review. The report reviews the available published information on the relative biological effectiveness (RBE) of neutrons and on the physical basis for the neutron quality factor for use in personnel dosimetry programs. It is concluded that some, but by no means all, of the RBE data supports an increased quality factor, but the relevance of this data to the quality factor for use in radiaton protection is not clear for two reasons. Firstly, the biological endpoints are not all directly extrapolatable to late stochastic effects in humans, and secondly, the current conservative selection of a quality factor for neutrons, and the conservative practise of equating whole body dose to the maximum dose equivalent, leads to a factor of about 10 conservatism in the assignment of neutron dose equivalents. The overall conclusion of the review is that there is no compelling reason to increase the quality factor for neutrons at least until the ICRP has completed its comprehensive review of the subject. 58 refs

  8. Sleep quality and some factors affecting sleep quality in the students living in the residence hall of a university

    OpenAIRE

    Ozge Yavuz Sari; Sarp Uner; Berkem Buyukakkus; Emine Ozlem Bostanci; Aytek Huseyin Celiksoz; Mehmet Budak

    2015-01-01

    AIM: Sleep disorders are remarkable public health problems as they adversely affect physical, mental and social health and may cause accidents and decline in academic performance and labor productivity. Aim of the study is assessing sleep quality and determining some factors affecting sleep quality in the students living in the residence hall of a university. METHOD: It is a cross sectional study conducted with 277 students, 180 of whom are female. Data were collected via a questionnaire ...

  9. Influence of photon beam energy on the dose enhancement factor caused by gold and silver nanoparticles: An experimental approach

    International Nuclear Information System (INIS)

    Guidelli, Eder José; Baffa, Oswaldo

    2014-01-01

    Purpose: Noble metal nanoparticles have found several medical applications in the areas of radiation detection; x-ray contrast agents and cancer radiation therapy. Based on computational methods, many papers have reported the nanoparticle effect on the dose deposition in the surrounding medium. Here the authors report experimental results on how silver and gold nanoparticles affect the dose deposition in alanine dosimeters containing several concentrations of silver and gold nanoparticles, for five different beam energies, using electron spin resonance spectroscopy (ESR). Methods: The authors produced alanine dosimeters containing several mass percentage of silver and gold nanoparticles. Nanoparticle sizes were measured by dynamic light scattering and by transmission electron microscopy. The authors determined the dose enhancement factor (DEF) theoretically, using a widely accepted method, and experimentally, using ESR spectroscopy. Results: The DEF is governed by nanoparticle concentration, size, and position in the alanine matrix. Samples containing gold nanoparticles afford a DEF higher than 1.0, because gold nanoparticle size is homogeneous for all gold concentrations utilized. For samples containing silver particles, the silver mass percentage governs the nanoparticles size, which, in turns, modifies nanoparticle position in the alanine dosimeters. In this sense, DEF decreases for dosimeters containing large and segregated particles. The influence of nanoparticle size-position is more noticeable for dosimeters irradiated with higher beam energies, and dosimeters containing large and segregated particles become less sensitive than pure alanine (DEF < 1). Conclusions: ESR dosimetry gives the DEF in a medium containing metal nanoparticles, although particle concentration, size, and position are closely related in the system. Because this is also the case as in many real systems of materials containing inorganic nanoparticles, ESR is a valuable tool for

  10. Influence of photon beam energy on the dose enhancement factor caused by gold and silver nanoparticles: An experimental approach.

    Science.gov (United States)

    Guidelli, Eder José; Baffa, Oswaldo

    2014-03-01

    Noble metal nanoparticles have found several medical applications in the areas of radiation detection; x-ray contrast agents and cancer radiation therapy. Based on computational methods, many papers have reported the nanoparticle effect on the dose deposition in the surrounding medium. Here the authors report experimental results on how silver and gold nanoparticles affect the dose deposition in alanine dosimeters containing several concentrations of silver and gold nanoparticles, for five different beam energies, using electron spin resonance spectroscopy (ESR). The authors produced alanine dosimeters containing several mass percentage of silver and gold nanoparticles. Nanoparticle sizes were measured by dynamic light scattering and by transmission electron microscopy. The authors determined the dose enhancement factor (DEF) theoretically, using a widely accepted method, and experimentally, using ESR spectroscopy. The DEF is governed by nanoparticle concentration, size, and position in the alanine matrix. Samples containing gold nanoparticles afford a DEF higher than 1.0, because gold nanoparticle size is homogeneous for all gold concentrations utilized. For samples containing silver particles, the silver mass percentage governs the nanoparticles size, which, in turns, modifies nanoparticle position in the alanine dosimeters. In this sense, DEF decreases for dosimeters containing large and segregated particles. The influence of nanoparticle size-position is more noticeable for dosimeters irradiated with higher beam energies, and dosimeters containing large and segregated particles become less sensitive than pure alanine (DEF nanoparticles, although particle concentration, size, and position are closely related in the system. Because this is also the case as in many real systems of materials containing inorganic nanoparticles, ESR is a valuable tool for investigating DEF. Moreover, these results alert to the importance of controlling the size-position of

  11. Influence of photon beam energy on the dose enhancement factor caused by gold and silver nanoparticles: An experimental approach

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, Eder José, E-mail: ederguidelli@pg.ffclrp.usp.br; Baffa, Oswaldo [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901 Ribeirão Preto, SP (Brazil)

    2014-03-15

    Purpose: Noble metal nanoparticles have found several medical applications in the areas of radiation detection; x-ray contrast agents and cancer radiation therapy. Based on computational methods, many papers have reported the nanoparticle effect on the dose deposition in the surrounding medium. Here the authors report experimental results on how silver and gold nanoparticles affect the dose deposition in alanine dosimeters containing several concentrations of silver and gold nanoparticles, for five different beam energies, using electron spin resonance spectroscopy (ESR). Methods: The authors produced alanine dosimeters containing several mass percentage of silver and gold nanoparticles. Nanoparticle sizes were measured by dynamic light scattering and by transmission electron microscopy. The authors determined the dose enhancement factor (DEF) theoretically, using a widely accepted method, and experimentally, using ESR spectroscopy. Results: The DEF is governed by nanoparticle concentration, size, and position in the alanine matrix. Samples containing gold nanoparticles afford a DEF higher than 1.0, because gold nanoparticle size is homogeneous for all gold concentrations utilized. For samples containing silver particles, the silver mass percentage governs the nanoparticles size, which, in turns, modifies nanoparticle position in the alanine dosimeters. In this sense, DEF decreases for dosimeters containing large and segregated particles. The influence of nanoparticle size-position is more noticeable for dosimeters irradiated with higher beam energies, and dosimeters containing large and segregated particles become less sensitive than pure alanine (DEF < 1). Conclusions: ESR dosimetry gives the DEF in a medium containing metal nanoparticles, although particle concentration, size, and position are closely related in the system. Because this is also the case as in many real systems of materials containing inorganic nanoparticles, ESR is a valuable tool for

  12. Feedstock Quality Factor Calibration and Data Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Richard D. Boardman; Tyler L. Westover; Garold L. Gresham

    2010-05-01

    The goal of the feedstock assembly operation is to deliver uniform, quality-assured feedstock materials that will enhance downstream system performance by avoiding problems in the conversion equipment. In order to achieve this goal, there is a need for rapid screening tools and methodologies for assessing the thermochemical quality characteristics of biomass feedstock through the assembly process. Laser-induced breakdown spectroscopy (LIBS) has been identified as potential technique that could allow rapid elemental analyses of the inorganic content of biomass feedstocks; and consequently, would complement the carbohydrate data provided by near-infrared spectrometry (NIRS). These constituents, including Si, K, Ca, Na, S, P, Cl, Mg, Fe and Al, create a number of downstream problems in thermochemical processes. In particular, they reduce the energy content of the feedstock, influence reaction pathways, contribute to fouling and corrosion within systems, poison catalysts, and impact waste streams.

  13. Quality attributes and socio-demographic factors affecting channel choices

    OpenAIRE

    Lupín, Beatriz; Rodríguez, Elsa Mirta M.

    2012-01-01

    Potato is an important staple food and horticultural crop for Argentina and it is included in almost every meal prepared by households. The annual average per capita consumption of potatoes is 40 kg. Despite the rapid rise of supermarkets, small fruit and vegetable shops still dominate horticultural retail in Argentina. The fresh potato quality is a wide and subjective notion that deals with different kinds of attributes e.g., colour, flavor, nutritional contents, added substances during the ...

  14. Factors related to the quality of life of older prisoners.

    Science.gov (United States)

    De Smet, Stefaan; De Donder, Liesbeth; Ryan, Denis; Van Regenmortel, Sofie; Brosens, Dorien; Vandevelde, Stijn

    2017-06-01

    There is evidence of an increasing emphasis on the relevance of the quality of life-paradigm as an outcome measure for clients in geriatric, forensic, as well as correctional care. This paper aims to explore to what extent variables that were categorized according to the main areas of the Good Lives Model ('the self', 'the body' and 'social life') are related to the quality of life domains of older imprisoned offenders. Data were collected by means of a structured questionnaire administered in individual interviews with 93 older prisoners aged 60 years and over in 16 prisons of the Dutch-speaking region in Belgium. Characteristics of the main GLM-areas were identified by specifically designed items as well three validated instruments (psychiatric disorders, loneliness, and frailty). Dependent variables consisted of the four sub-domains of the WHOQOL-BREF instrument which measures quality of life in four domains, namely: (1) physical health, (2) psychological health, (3) social relationships, and (4) environment. Structural equation modelling (SEM) was used for statistical analysis. Individual variables, such as satisfaction with activities, were related to the older prisoners' QoL in several domains simultaneously. Other than suicidal ideation, psychopathological symptoms had no significant relation to quality of life. Approaches enabling older prisoner to disclose their interests, experiences, and feelings are important in prison. Special attention should be given to psychiatric and age-related symptoms of older prisoners, since they may not be noted by the prison staff, as older prisoners seem to be poorer self-advocates as compared to their younger peers.

  15. PSYCHOSOCIAL FACTORS CONSUMER PERCEPTION OF QUALITY DENTAL CARE

    Directory of Open Access Journals (Sweden)

    Надежда Алексеевна Кудинова

    2013-04-01

    Full Text Available Purpose to examine the motivational space, values and health-social and psychological portrait of patients who rated the quality of dental care.Methodology historical, sociological, statistical. Results: In a market economy, patients’ satisfaction is of one of the most important regulators of demand.  Estimate of the quality of dental services (QDS depends on the patients having stable socio-psychological status being in a certain system of values, in space of some motives and needs. Got data have revealed that nearly 17.5% of patients dissatisfied with the quality of dental care, but the size of the motivational area of this group by nearly 20% higher than that of their opponents. With the structure of the motives are no such positions as "visiting the dentist enters my behavior stereotype", "I want to know the details of my dental health" and "The process of dental treatment gives me pleasure" In the group of patients who are satisfied QDS, relevance value orientation "good health" is 1.5 times the value of "education" in 2.5 times, and the value of "high social security" is 4.5 times higher than among the dissatisfied patients.Practical implications public health and health care.DOI: http://dx.doi.org/10.12731/2218-7405-2013-2-22

  16. PSYCHOSOCIAL FACTORS CONSUMER PERCEPTION OF QUALITY DENTAL CARE

    Directory of Open Access Journals (Sweden)

    Kudinova Nadezhda Alekseevna

    2013-02-01

    Full Text Available Purpose to examine the motivational space, values ​​and health-social and psychological portrait of patients who rated the quality of dental care. Methodology historical, sociological, statistical. Results: In a market economy, patients’ satisfaction is of one of the most important regulators of demand. Estimate of the quality of dental services (QDS depends on the patients having stable socio-psychological status being in a certain system of values, in space of some motives and needs. Got data have revealed that nearly 17.5% of patients dissatisfied with the quality of dental care, but the size of the motivational area of this group by nearly 20% higher than that of their opponents. With the structure of the motives are no such positions as "visiting the dentist enters my behavior stereotype", "I want to know the details of my dental health" and "The process of dental treatment gives me pleasure" In the group of patients who are satisfied QDS, relevance value orientation "good health" is 1.5 times the value of "education" in 2.5 times, and the value of "high social security" is 4.5 times higher than among the dissatisfied patients. Practical implications public health and health care.

  17. Factors influencing the surface quality of polished tool steels

    International Nuclear Information System (INIS)

    Rebeggiani, S; Rosén, B-G

    2014-01-01

    Today’s demands on surface quality of moulds for injection moulding of plastic components involve no/low defect contents and roughness levels in the nm-range for high gloss applications. Material properties as well as operating conditions influence the mould finish, and thus the final surface of moulded products. This paper focuses on how particle content and different polishing strategies influence final surface qualities of moulds. Visual estimations of polished tool steel samples were combined with non-contact 3D-surface texture analysis in order to correlate traditional assessments to more quantitative methods, and to be able to analyse the surfaces at nanometre-level. It was found that steels with a lower proportion of particles, like carbides and oxides, gave rise to smoother polished surfaces. In a comparative study of polishers from different polishing shops, it was found that while different surface preparation strategies can lead to similar final roughness, similar preparation techniques can produce high-quality surfaces from different steel grades. However, the non-contact 3D-surface texture analysis showed that not all smooth polished surfaces have desirable functional topographies for injection moulding of glossy plastic components. (paper)

  18. Factors that determine the quality of bigeye tuna, caught in the western tropical Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    C.C. Nóbrega

    2014-06-01

    Full Text Available Tuna are highly prized in Oriental cuisine, and the bigeye tuna (Thunnus obesus is of great commercial importance. Quality is assessed by the tuna meat quality, freshness, texture and fat, which can be altered by factors inherent to capture, such as days of onboard storage, months of the year, whether the catch was living or dead, fish weight and year. These factors were correlated to identify those that affect quality. We obtained data from nine vessels, from January 2007 to April 2010, creating an information bank of 21,908 bigeye tuna. Fish quality and parameters were related using multiple linear regression analysis, in which the variables were included in the model by a stepwise procedure (F>4. We found that live catch, heavier fish and fewer days of storage positively affected the quality, and that there is a seasonality of quality related to biological factors, which are not amenable to control.

  19. Quality factors in the life cycle of software oriented to safety systems in nuclear power plants

    International Nuclear Information System (INIS)

    Nunez McLeod, J.E.; Rivera, S.S.

    1997-01-01

    The inclusion of software in safety related systems for nuclear power plants, makes it necessary to include the software quality assurance concept. The software quality can be defined as the adjustment degree between the software and the specified requirements and user expectations. To guarantee a certain software quality level it is necessary to make a systematic and planned set of tasks, that constitute a software quality guaranty plan. The application of such a plan involves activities that should be performed all along the software life cycle, and that can be evaluated through the so called quality factors, due to the fact that the quality itself cannot be directly measured, but indirectly as some of it manifestations. In this work, a software life cycle model is proposed, for nuclear power plant safety related systems. A set os software quality factors is also proposed , with its corresponding classification according to the proposed model. (author) [es

  20. Association between socioeconomic factors and sleep quality in an urban population-based sample in Germany

    DEFF Research Database (Denmark)

    Anders, Markus P; Breckenkamp, Jürgen; Blettner, Maria

    2014-01-01

    , but also health status, are also associated with sleep quality and can influence in part the socioeconomic levels seen in sleep quality. CONCLUSION: SES and sleep quality are associated. However, there are important additional determinants that influence the level of association between SES and sleep......BACKGROUND: Good sleep quality is essential for recovery. The risk factors of sleep disorders have been extensively investigated, but there is sparse information on the association of socioeconomic factors with a person's sleep quality. The aim of the present analysis is to investigate...... from the baseline survey taken in 2004. Sleep quality for the same participants was measured with in-depth personal interviews in 2006 using the Pittsburgh Sleep Quality Index, together with other relevant characteristics (e.g. anxiety, depression and health status). Multiple logistic regression...

  1. The analysis on factors affecting the quality of proton magnetic resonance spectroscopy of prostate

    International Nuclear Information System (INIS)

    Mao Lijuan; Lin Erjian; Guo Yan; Liu Mingjuan; Meng Quanfei

    2009-01-01

    Objective: To discuss all sorts of factors affecting the quality of proton magnetic resonance spectroscopy of prostate and try to find a better method to improve the quality and accuracy of MRS in prostate, and to be helpful to clinical diagnosis. Methods: Three-dimensional proton MR spectroscopy of the prostate was performed on 15 patients with prostate illness and 35 healthy volunteers. And all sorts of factors affecting the exam were analyzed. Results: The impact factors included subjective and objective factors. The subjective factors included the cooperation of patients, the localization, and the selection of ROI. The objective factors included the magnetic homogeneity, effects of peripheral tissue, lesion of the prostate, foreign body, staxis after puncture and contrast medium after enhancement. Conclusion: Just by controlling the subjective and objective factors, the quality and accuracy of the exam can be improved. (authors)

  2. Mitigation of beam fluctuation due to atmospheric turbulence and prediction of control quality using intelligent decision-making tools.

    Science.gov (United States)

    Raj, A Arockia Bazil; Selvi, J Arputha Vijaya; Kumar, D; Sivakumaran, N

    2014-06-10

    In free-space optical link (FSOL), atmospheric turbulence causes fluctuations in both intensity and phase of the received beam and impairing link performance. The beam motion is one of the main causes for major power loss. This paper presents an investigation on the performance of two types of controller designed for aiming a laser beam to be at a particular spot under dynamic disturbances. The multiple experiment observability nonlinear input-output data mapping is used as the principal components for controllers design. The first design is based on the Taguchi method while the second is artificial neural network method. These controllers process the beam location information from a static linear map of 2D plane: optoelectronic position detector, as observer, and then generate the necessary outputs to steer the beam with a microelectromechanical mirror: fast steering mirror. The beam centroid is computed using monopulse algorithm. Evidence of suitability and effectiveness of the proposed controllers are comprehensively assessed and quantitatively measured in terms of coefficient of correlation, correction speed, control exactness, centroid displacement, and stability of the receiver signal through the experimental results from the FSO link setup established for the horizontal range of 0.5 km at an altitude of 15.25 m. The test field type is open flat terrain, grass, and few isolated obstacles.

  3. Vibration factors impact analysis on aerial film camera imaging quality

    Science.gov (United States)

    Xie, Jun; Han, Wei; Xu, Zhonglin; Tan, Haifeng; Yang, Mingquan

    2017-08-01

    Aerial film camera can acquire ground target image information advantageous, but meanwhile the change of aircraft attitude, the film features and the work of camera inside system could result in a vibration which could depress the image quality greatly. This paper presented a design basis of vibration mitigation stabilized platform based on the vibration characteristic of the aerial film camera and indicated the application analysis that stabilized platform could support aerial camera to realize the shoot demand of multi-angle and large scale. According to the technique characteristics of stabilized platform, the development direction are high precision, more agility, miniaturization and low power.

  4. Pediatric Coccidioidomycosis Patients: Perceptions, Quality of Life and Psychosocial Factors

    Directory of Open Access Journals (Sweden)

    Erin Mary Gaab

    2015-08-01

    Full Text Available Research investigating the effects of coccidioidomycosis (valley fever on children and the psychosocial implications of this disease in general is lacking. This study reviews what is known about pediatric coccidioidomycosis patients. It documents the psychological functioning, quality of life, and illness perceptions of a sample of coccidioidomycosis patient families. Primary caregivers of pediatric patients and patients from a major hospital in the San Joaquin Valley of California were interviewed regarding their perceptions of disease detection, access to care and the patient/family experience.

  5. Prediction of lung density changes after radiotherapy by cone beam computed tomography response markers and pre-treatment factors for non-small cell lung cancer patients

    DEFF Research Database (Denmark)

    Bernchou, Uffe; Hansen, Olfred; Schytte, Tine

    2015-01-01

    BACKGROUND AND PURPOSE: This study investigates the ability of pre-treatment factors and response markers extracted from standard cone-beam computed tomography (CBCT) images to predict the lung density changes induced by radiotherapy for non-small cell lung cancer (NSCLC) patients. METHODS...

  6. Effect of Occupational Factors on the Quality of Life of Workers in ...

    African Journals Online (AJOL)

    as work stress and job satisfaction. These occupational factors generally affect the physical, social and mental states of an individual; these factors being domains of quality of life; will invariably reflect the individual's wellbeing as a result of his occupation when assessed. Related work factors such as job satisfaction, job.

  7. Key Factors of Quality in the Sector of Tourism Services Providers: Case Study: Czech Republic

    Directory of Open Access Journals (Sweden)

    Ida Vajčnerová

    2014-01-01

    Full Text Available The paper summarizes main results of partial research aimed at detection of the key factors affecting quality in the sector of tourism services providers, namely tour operators and travel agencies. A primary questionnaire survey was conducted; the researched factors were distributed in the context of service quality dimensions (Grönroos model; the dimensions were tested in relation to sex, age and education of the respondents (ANOVA; Brown-Forsythe test. Assurance was identified as the most important dimension. The output of the study is determining the significance of individual quality factors from the perspective of a potential customer when selecting a service provider.

  8. Transverse equilibria in linear collider beam-beam collisions

    International Nuclear Information System (INIS)

    Rosenzweig, J.B.; Chen, Pisin

    1991-01-01

    It has been observed in simulations of the beam-beam interaction in linear colliders that a near equilibrium pinched state of the colliding beams develops when the disruption parameter is large (D much-gt 1). In this state the beam transverse density distributions are peaked at center, with long tails. The authors present here an analytical model of the equilibrium approached by the beams, that of a generalized Bennett pinch which develops through collisionless damping due to the strong nonlinearity of the beam-beam interaction. In order to calculate the equilibrium pinched beam size, an estimation of the rms emittance growth is made which takes into account the partial adiabaticity of the collision. This pinched beam size is used to derive the luminosity enhancement factors whose scaling is in agreement with the simulation results for both D and thermal factor A = σ z /β * large, and explains the previously noted cubic relationship between round and flat beam enhancement factors

  9. A Multivariate Evaluation of Factors Affecting the Quality of Freshly Frozen Tissue Specimens.

    Science.gov (United States)

    Wang, Tong-Hong; Chen, Chin-Chuan; Liang, Kung-Hao; Chen, Chi-Yuan; Chuang, Wen-Yu; Ueng, Shir-Hwa; Chu, Pao-Hsien; Huang, Chung-Guei; Chen, Tse-Ching; Hsueh, Chuen

    2017-08-01

    Well-prepared and preserved freshly frozen specimens are indispensable materials for clinical studies. To manage specimen quality and to understand the factors potentially affecting specimen quality during preservation processes, we analyzed the quality of RNA and genomic DNA of various tissues collected between 2002 and 2011 in Linkou Chang Gung Memorial Hospital, Taiwan. During this period, a total of 1059 freshly frozen specimens from eight major cancer categories were examined. It was found that preservation duration, organ origin, and tissue type could all influence the quality of RNA samples. The increased preservation period correlated with decreased RNA quality; the brain, breast, and stomach RNA specimens displayed faster degradation rates than those of other organs, and RNA specimens isolated from tumor tissues were apparently more stable than those of other tissues. These factors could all be used as quality predictors of RNA quality. In contrast, almost all analyses revealed that the genomic DNA samples had good quality, which was not influenced by the aforementioned factors. The results assisted us in determining preservation factors that affect specimen quality, which could provide evidence for improving processes of sample collection and preservation. Furthermore, the results are also useful for researchers to adopt as the evaluation criteria for choosing specimen collection and preservation strategies.

  10. Factors affecting quality of nurse shift handover in the emergency department.

    Science.gov (United States)

    Thomson, Heather; Tourangeau, Ann; Jeffs, Lianne; Puts, Martine

    2018-04-01

    The aim of this study was to explore and test factors hypothesized to influence quality of Emergency Department nurse-to-nurse shift handover communication. Nurse-to-nurse shift handover communication includes the transfer of information and responsibility for patients at shift change. The unique environment of the Emergency Department, where there is a high degree of patient unpredictability, increased patient volumes and rapid patient turnover, can create challenges for high quality handover communication. There is considerable literature addressing handover communication and factors that influence quality or effectiveness. However, few studies have empirically tested those factors. A quantitative, cross-sectional design was used to test a conceptual model of factors hypothesized to influence quality of handover communication. In 2014, data were gathered using surveys mailed to Emergency Department nurses across Ontario, Canada. The final eligible sample was 231 of 576 for an overall response rate of 40.1%. Analysis was performed using backwards elimination stepwise multiple linear regression. Four statistically significant explanatory variables were retained in the final multiple regression model, explaining 34% (p quality. Handover quality was increased when patients flowed smoothly through triage, when nurses experienced positive intrusions, in the presence of a positive safety climate and when there were positive relationships between incoming and outgoing nurses. By understanding those factors that contribute to handover quality, it is possible to develop targeted interventions aimed at improving the quality of Emergency Department nurse-to-nurse shift handover. © 2017 John Wiley & Sons Ltd.

  11. Optimization of the pion beam for the HADES detector and determination of the {eta} form factor in proton-proton reactions at 2.2 GeV; Optimierung des Pionenstrahls zum HADES-Detektor und Bestimmung des {eta}-Formfaktors in Proton-Proton-Reaktionen bei 2.2 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Spruck, Bjoern

    2008-02-08

    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 {eta} 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 {eta} Dalitz decay in p+p reactions at 2.2 GeV kinetic energy to determine the electromagnetic transition form factor of the {eta} meson. A fit to the data leads to a form factor slope of b=2.2{sub -1.4}{sup +1.2} GeV{sup -2}. This corresponds to a pole mass of {lambda}=680{sub -130}{sup +460} MeV/c{sup 2}. It has been shown, that a semi-exclusive analysis of the {eta} Dalitz decay within the event hypothesis framework including a kinematical fit is feasible. (orig.)

  12. Quality of synthetic speech perceptual dimensions, influencing factors, and instrumental assessment

    CERN Document Server

    Hinterleitner, Florian

    2017-01-01

    This book reviews research towards perceptual quality dimensions of synthetic speech, compares these findings with the state of the art, and derives a set of five universal perceptual quality dimensions for TTS signals. They are: (i) naturalness of voice, (ii) prosodic quality, (iii) fluency and intelligibility, (iv) absence of disturbances, and (v) calmness. Moreover, a test protocol for the efficient indentification of those dimensions in a listening test is introduced. Furthermore, several factors influencing these dimensions are examined. In addition, different techniques for the instrumental quality assessment of TTS signals are introduced, reviewed and tested. Finally, the requirements for the integration of an instrumental quality measure into a concatenative TTS system are examined.

  13. Computation of beam quality parameters for Mo/Mo, Mo/Rh, Rh/Rh, and W/Al target/filter combinations in mammography

    International Nuclear Information System (INIS)

    Kharrati, Hedi; Zarrad, Boubaker

    2003-01-01

    A computer program was implemented to predict mammography x-ray beam parameters in the range 20-40 kV for Mo/Mo, Mo/Rh, Rh/Rh, and W/Al target/filter combinations. The computation method used to simulate mammography x-ray spectra is based on the Boone et al. model. The beam quality parameters such as the half-value layer (HVL), the homogeneity coefficient (HC), and the average photon energy were computed by simulating the interaction of the spectrum photons with matter. The checking of this computation was done using a comparison of the results with published data and measured values obtained at the Netherlands Metrology Institute Van Swinden Laboratorium, National Institute of Standards and Technology, and International Atomic Energy Agency. The predicted values with a mean deviation of 3.3% of HVL, 3.7% of HC, and 1.5% of average photon energy show acceptable agreement with published data and measurements for all target/filter combinations in the 23-40 kV range. The accuracy of this computation can be considered clinically acceptable and can allow an appreciable estimation for the beam quality parameters

  14. Stability of period and quality factor of free core nutation

    Czech Academy of Sciences Publication Activity Database

    Vondrák, Jan; Ron, Cyril

    2009-01-01

    Roč. 6, č. 3 (2009), s. 217-224 ISSN 1214-9705. [Czech-Polish Workshop on Recent Geodynamics /9./. Náchod, 12.11.2008-14.11.2009] R&D Projects: GA MŠk(CZ) LC506 Institutional research plan: CEZ:AV0Z10030501 Keywords : Earth orientation * nutation * geophysical excitation * VLBI Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.275, year: 2009

  15. Nontraditional factors influencing the quality of life of hemodialysis patients

    Directory of Open Access Journals (Sweden)

    Diana-Cristina Varela

    2014-06-01

    Full Text Available Introduction: The prevalence of CKD patients in advanced stages with dialysis requirement continues to grow. A goal for the medical team, the patient and their caregivers is to provide a treatment that offers an impact on the prognosis and quality of life (QOL. Methods: In 100 patients with CKD on hemodialysis, randomized assigned, the quality of life by SF-36 was assessed, it was evaluated the functional capacity using the Karnofsky, ability to perform basic tasks of daily life through the index Barthel, presence of depression using the Beck test, family functioning through family APGAR, cognitive state through Minimental and presence of comorbidities using the Charlson index correlated with the sum of physical components (PCS and mental components (MCS of the SF-36 in patients in two renal units in Medellín and Bogotá, Colombia. Results: A decrease in QOL in the physical components (PCS Mental components (MCS regarding the general population. A significant correlation between low PCS and diabetes mellitus (-16 p=0.008 95% CI 2.49 was found. Low MCS showed relation with PTH (p=0.046 95% CI 0.000-0.014, Karnofsky index (p=0.034 95% CI 0.244 to 5.984 and Beck depression test (p=0.000 95% CI -13.606 to 6.253. Conclusions: The QOL of hemodialysis patients is affected with more impact on PCS, there is significant relationship between MCS with functional status and depression. To improve QOL in hemodialysis patients, non traditionally-measured variables should be measured and monitored and the therapeutic focus should be optimized addressed to physical rehabilitation, nutritional, functional and psychological state.

  16. The development of a postal method to assess X-ray beam parameters and image quality in dental radiology

    International Nuclear Information System (INIS)

    Fenton, D.M.

    1994-10-01

    Intraoral radiographs are an extremely valuable diagnostic tool in dentistry. Radiography permits the early detection and diagnosis of dental disease and consequently is used extensively. However, public concern about radiation exposure has increased in recent times. This concern is reflected in national and international law, to the extent that, the basic principles of radiological protection, that is, justification, optimisation and dose limitation are written into law. Furthermore, in Ireland, the regulations, as outlined in the Code of Practice for Radiological Protection in Dentistry, require intraoral dental X-ray machines to perform to certain standards. A report of a direct survey of 164 intraoral dental X-ray machines is given in this study. The survey covered mechanical, electrical as well as radiation safety. Inadequacies with respect to focus to skin distance and timer accuracy were found in 45% and 42% of the machines surveyed. Ninety eight machines were assessed for electrical safety in which 48% were found to be unsafe. The results indicate that a complete assessment of the performance of dental X-ray units in Ireland is required. However, as there are in excess of 800 dental X-ray machines located throughout the country, such an assessment would be very costly for the regulatory authority. The development of a postal method for the assessment of the performance of dental X-ray machines is described in this study. This postal method provides information on the kV, total filtration, beam width and timer linearity and is undertaken by means of a penetrameter and film envelopes for exposure to the X-ray set under examination, together with a questionnaire that requests information on environment in which the machine is located. Using this method an accuracy of +-5% of the actual value was achieved in the measurement of kVp. The penetrameter was also used to assess whether or not the filtration of a particular machine complies with the regulations. This

  17. The Impact of Soft Factors on Quality Improvement in Manufacturing Industry

    Science.gov (United States)

    Chan, Shiau Wei; Fauzi Ahmad, Md; Kong, Mei Wan

    2017-08-01

    Nowadays, soft factors have become the key factors of success in quality improvement of an organisation. Many organisations have neglected the importance of soft factors, this may influence the organisational performance. Hence, the purpose of this research is to examine the impact of soft factors on quality improvement in manufacturing industries. Six hypotheses were examined while considering six dimensions of soft factors including management commitment, customer focus, supplier relationship, employee involvement, training and education, and reward and recognition that have a positive impact on quality improvement. In this study, eighty one managers from the quality department were randomly selected in the manufacturing industry in Batu Pahat, Johor. The questionnaires were distributed to them. The researcher analysed the quantitatively collected data using descriptive analysis and correlation analysis. The findings of this study revealed that all soft factors are correlated to the quality improvement in an organisation with a high significant value but the regression analysis shows that the supplier relationship and employee involvement has more significant impact on quality improvement as compared to other soft factors which contributes of this study.

  18. Effective quality factors for neutrons based on the revised ICRP/ICRU recommendations

    International Nuclear Information System (INIS)

    Veinot, K. G.; Hertel, N. E.

    2005-01-01

    The quality factor (Q) is intended to relate the biological effectiveness of a radiation to the absorbed dose delivered in tissue. Quality factors are defined as a function of the unrestricted linear energy transfer (L) relationship in water and are used with operational quantities. Radiation weighting factors (wR) are used in protection quantities to take into account total radiation detriment. While the International Commission on Radiological Protection (ICRP) defines the Q(L) relationship, the International Commission on Radiation Units and Measurements (ICRU) recommends the charged particle stopping power and range data. If either of these data recommendations change, the quality factors must be recomputed. The latest guidance from both organisations applicable to neutron quality factors are the ICRP Publication 60 (Q(L) relationship) and the ICRU Report 49 (stopping power and range data). In the present study, absorbed dose conversion coefficients (pGy cm 2 ) were calculated for two operational quantities defined by the ICRU - the ambient absorbed dose and the personal absorbed dose. Dose-equivalent (pSv cm 2 ) conversion coefficients were also computed using mean quality factors based on ICRP 60 and ICRU 49 recommendations. Effective quality factors were then calculated from the ratio of the dose-equivalent to the absorbed dose conversion coefficients for both the personal dose-equivalent and ambient dose-equivalent and compared to values reported in the literature. (authors)

  19. Detector dose response in megavoltage small photon beams. II. Pencil beam perturbation effects

    International Nuclear Information System (INIS)

    Bouchard, Hugo; Duane, Simon; Kamio, Yuji; Palmans, Hugo; Seuntjens, Jan

    2015-01-01

    Purpose: To quantify detector perturbation effects in megavoltage small photon fields and support the theoretical explanation on the nature of quality correction factors in these conditions. Methods: In this second paper, a modern approach to radiation dosimetry is defined for any detector and applied to small photon fields. Fano’s theorem is adapted in the form of a cavity theory and applied in the context of nonstandard beams to express four main effects in the form of perturbation factors. The pencil-beam decomposition method is detailed and adapted to the calculation of perturbation factors and quality correction factors. The approach defines a perturbation function which, for a given field size or beam modulation, entirely determines these dosimetric factors. Monte Carlo calculations are performed in different cavity sizes for different detection materials, electron densities, and extracameral components. Results: Perturbation effects are detailed with calculated perturbation functions, showing the relative magnitude of the effects as well as the geometrical extent to which collimating or modulating the beam impacts the dosimetric factors. The existence of a perturbation zone around the detector cavity is demonstrated and the approach is discussed and linked to previous approaches in the literature to determine critical field sizes. Conclusions: Monte Carlo simulations are valuable to describe pencil beam perturbation effects and detail the nature of dosimetric factors in megavoltage small photon fields. In practice, it is shown that dosimetric factors could be avoided if the field size remains larger than the detector perturbation zone. However, given a detector and beam quality, a full account for the detector geometry is necessary to determine critical field sizes

  20. Factors related to quality of life among older adults in Bangladesh: A cross sectional survey.

    Science.gov (United States)

    Uddin, Mohammad Abbas; Soivong, Pratum; Lasuka, Duangruedee; Juntasopeepun, Phanida

    2017-12-01

    This cross-sectional design study aimed to describe quality of life and examine factors related to quality of life among older adults in Bangladesh. Convenience sampling was used to recruit 280 older adults from ten villages in two southern districts. The results demonstrate that the majority of the participants reported an overall moderate score of quality of life. Moreover, participants' sleep problems, depression, religiosity, and activities of daily living were negatively correlated with quality of life whereas social support and health service availability were positively correlated with quality of life. Implementing intervention programs upon the significant related factors to improve older adults' quality of life is recommended. © 2017 John Wiley & Sons Australia, Ltd.

  1. Winter wheat quality monitoring and forecasting system based on remote sensing and environmental factors

    International Nuclear Information System (INIS)

    Haiyang, Yu; Yanmei, Liu; Guijun, Yang; Xiaodong, Yang; Chenwei, Nie; Dong, Ren

    2014-01-01

    To achieve dynamic winter wheat quality monitoring and forecasting in larger scale regions, the objective of this study was to design and develop a winter wheat quality monitoring and forecasting system by using a remote sensing index and environmental factors. The winter wheat quality trend was forecasted before the harvest and quality was monitored after the harvest, respectively. The traditional quality-vegetation index from remote sensing monitoring and forecasting models were improved. Combining with latitude information, the vegetation index was used to estimate agronomy parameters which were related with winter wheat quality in the early stages for forecasting the quality trend. A combination of rainfall in May, temperature in May, illumination at later May, the soil available nitrogen content and other environmental factors established the quality monitoring model. Compared with a simple quality-vegetation index, the remote sensing monitoring and forecasting model used in this system get greatly improved accuracy. Winter wheat quality was monitored and forecasted based on the above models, and this system was completed based on WebGIS technology. Finally, in 2010 the operation process of winter wheat quality monitoring system was presented in Beijing, the monitoring and forecasting results was outputted as thematic maps

  2. Chilled beam application guidebook

    CERN Document Server

    Butler, David; Gräslund, Jonas; Hogeling, Jaap; Lund Kristiansen, Erik; Reinikanen, Mika; Svensson, Gunnar

    2007-01-01

    Chilled beam systems are primarily used for cooling and ventilation in spaces, which appreciate good indoor environmental quality and individual space control. Active chilled beams are connected to the ventilation ductwork, high temperature cold water, and when desired, low temperature hot water system. Primary air supply induces room air to be recirculated through the heat exchanger of the chilled beam. In order to cool or heat the room either cold or warm water is cycled through the heat exchanger.

  3. Factors predicting team climate, and its relationship with quality of care in general practice

    OpenAIRE

    Goh, Teik T; Eccles, Martin P; Steen, Nick

    2009-01-01

    Abstract Background Quality of care in general practice may be affected by the team climate perceived by its health and non-health professionals. Better team working is thought to lead to higher effectiveness and quality of care. However, there is limited evidence available on what affects team functioning and its relationship with quality of care in general practice. This study aimed to explore individual and practice factors that were associated with team climate, and to explore the relatio...

  4. Nutrition myths - the factor influencing the quality of children's diets

    Directory of Open Access Journals (Sweden)

    Slávka Mrosková

    2016-03-01

    Full Text Available Aim: To analyse the influence of parents' belief in nutrition myths on the frequency of their serving certain foods to their children. Design: Cross-sectional study. Methods: Survey carried out with 297 respondents - parents of children aged 5-18 years. The data collection took place between September 2013 and December 2014. The questionnaire focussed on 14 nutrition myths related to selected foods (milk, dairy products, meat, offal, fruit, vegetables, eggs, fish, legumes, soya, and flour dishes. At the same time, the parents reported the frequency of their serving the monitored foods to their children. In the statistical analysis, Spearman's rank correlation coefficient was used. Results: For nine nutrition myths we found significant negative coefficients between a certain nutrition myth and the frequency of the serving of the food. The nutrition myths related to the consumption of fish (r = -0.328, eggs (r = -0.203, soya (r = -0.301; -0.290, offal (r = -0.155, meat (r = -0.128, milk (r = -0.272; -0.254, and fruit/vegetables (r = -0.104. Conclusion: The belief in nutrition myths appears to be a determinant modifying parental behaviour and subsequently the quality of children's diets.

  5. Impact of different beam set-up methods on quality of intensity modulated radiation therapy in non-small cell lung cancer

    International Nuclear Information System (INIS)

    Zhu Zhengfei; Xu Zhiyong; Chen Lanfei; Hu Weigang; Fan Min; Wu Kailiang; Xia Bing; Fu Xiaolong

    2010-01-01

    Objective: To investigate whether the change of beam set-up methods will influence the dosimetric quality of intensity modulated radiation therapy (IMRT) for non-small cell lung cancer (NSCLC). Methods: Twenty-one stage I-III NSCLC patients were selected for this study. The technique of step and shoot was used and three different beam set-up methods were chosen for IMRT planning including IMRT-7 with nine equal-spaced beams angled 0 degree, 51 degree, 102 degree, 153 degree, 204 degree, 255 degree and 306 degree; IMRT-5 with five equal-spaced beams angled 0 degree, 72 degree, 144 degree, 216 degree and 288 degree; and IMRT-5m which was created from IMRT-7 but excluded 2 fields (51 degree and 102 degree were omitted if there was lesion in the right lung, while 255 degree and 306 degree were excluded if there was lesion in the left lung). The dose constrains of normal lungs for IMRT were set according to V 5 -V 60 of normal lungs obtained from the same patient's actually treated 3D-CRT dose volume histogram. The prescription dose for IMRT started from 65 Gy, and then escalated or decreased step by step by 2 Gy once a time until best plan was obtained. Results: For normal lung dose, IMRT-5m had lower V 5 -V 25 than the other two groups; but there was no significant difference in V 30 -V 40 . IMRT-5 was the worst for V 45 -V 60 ; and mean lung dose was lowest in IMRT-5m. Dose parameters of esophagus and spinal cord, target conformity index, and total monitor units were all similar among difference plans. IMRT-5m had lowest heart V 40 compared to the other two groups. For target heterogeneity index, IMRT-5 was higher than IMRT-7, but there were no significant differences among IMRT-5m, IMRT-5 and IMRT-7. Compared to 3D-CRT, the prescription dose could be increased by (5.1±4.6) Gy for IMRT-7, (3.1±5.3) Gy for IMRT-5, and (5.5±4.8) Gy for IMRT-5m. Conclusions: Fewer beams and modified beam angles could result in similar, even better plan quality. (authors)

  6. 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, Jens Peter

    2016-01-01

    OBJECTIVE: We investigated the impact of deep inspiration breath-hold (DIBH) and tumour baseline shifts on image quality and registration uncertainty in image-guided DIBH radiotherapy (RT) for locally advanced lung cancer. METHODS: Patients treated with daily cone beam CT (CBCT)-guided free...... and visualization of tumour and anatomical structures. We examined the impact of tumour baseline shift between consecutive DIBHs on CBCT image quality. RESULTS: CBCT scans from 15 patients were analysed. Intraobserver image registration uncertainty was approximately 2 mm in both FB and DIBH, except...... for the craniocaudal direction in FB, where it was >3 mm. On the 31st fraction, the intraobserver uncertainty increased compared with the second fraction. This increase was more pronounced in FB. Image quality scores improved in DIBH compared with FB for all parameters in all patients. Simulated tumour baseline shifts...

  7. Factors Associated with the Utilization and Quality of Prenatal Care in Western Rural Regions of China

    Science.gov (United States)

    Dongxu, Wang; Yuhui, Shi; Stewart, Donald; Chun, Chang; Chaoyang, Li

    2012-01-01

    Purpose: The paper seeks to identify key features of prenatal care utilization and quality in western regions of China and to determine the factors affecting the quality of prenatal care. Design/methodology/approach: A descriptive, cross-sectional study was conducted. The instrument for the study was a 10-stem respondent-administered, structured…

  8. Change in Quality of Life after Rehabilitation: Prognostic Factors for Visually Impaired Adults

    Science.gov (United States)

    Langelaan, Maaike; de Boer, Michiel R.; van Nispen, Ruth M. A.; Wouters, Bill; Moll, Annette C.; van Rens, Ger H. M. B.

    2009-01-01

    The overall aim of rehabilitation for visually impaired adults is to improve the quality of life and (societal) participation. The objectives of this study were to obtain the short-term and long-term outcome of a comprehensive rehabilitation programme on quality of life for visually impaired adults, and prognostic baseline factors responsible for…

  9. Factors associated with poor sleep quality in patients with multiple sclerosis differ by disease duration

    NARCIS (Netherlands)

    Vitkova, Marianna; Gdovinova, Zuzana; Rosenberger, Jaroslav; Szilasiova, Jarmila; Nagyova, Iveta; Mikula, Pavol; Krokavcova, Martina; Groothoff, Johan W.; van Dijk, Jitse P.

    2014-01-01

    Background: Sleep disturbance is a common symptom of multiple sclerosis (MS) and knowledge about factors that contribute to poor sleep quality is scarce. Objective: The aim was to explore the differences in the prevalence and determinants of poor sleep quality in a sample of patients with MS with

  10. Prevalence and Predicting Factors for Commonly Neglected Sexual Side Effects to External-Beam Radiation Therapy for Prostate Cancer.

    Science.gov (United States)

    Frey, Anders; Pedersen, Christian; Lindberg, Henriette; Bisbjerg, Rasmus; Sønksen, Jens; Fode, Mikkel

    2017-04-01

    pursue. Frey A, Pedersen C, Lindberg H, et al. Prevalence and Predicting Factors for Commonly Neglected Sexual Side Effects to External-Beam Radiation Therapy for Prostate Cancer. J Sex Med 2017;14:558-565. Copyright © 2017 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.

  11. Prevalence of Apical Bone Defects and Evaluation of Associated Factors Detected with Cone-beam Computed Tomographic Images.

    Science.gov (United States)

    Lemagner, Fabien; Maret, Delphine; Peters, Ove A; Arias, Ana; Coudrais, Elisabeth; Georgelin-Gurgel, Marie

    2015-07-01

    Cone-beam computed tomographic (CBCT) imaging has been shown to be accurate for detecting apical bone defects (ABDs). Medium field of view CBCT imaging may provide apical images of the whole oral cavity at a resolution that is sufficient to allow ABDs to be located and measured. The aim of the work presented was to calculate the prevalence of ABDs from CBCT images as well as to assess some associated factors and their measurement. One hundred CBCT data sets with a voxel size of 0.2 mm were analyzed by 2 evaluators according to a standardized reading protocol. The number of maxillary and mandibular teeth, the presence of endodontic treatment, and the presence of ABDs associated with endodontic treatment were identified, and the presence of intraradicular posts was documented. The size of ABDs detected was measured, and they were classified according to the Cone Beam Computed Tomography Periapical Index. A total of 2368 teeth and 100 subjects were analyzed. The prevalence of ABDs in subjects was 78%; in 8.6% of the sample teeth, ABDs were present, and 38.2% of endodontically treated maxillary molars were affected by it. Endodontic treatment was significantly associated with an increased risk for the presence of an ABD (P = .0001); 40.8% of endodontically treated teeth were associated with an ABD. This rate increased to 85.9% in endodontically treated maxillary molars. Placement of a post was significantly associated with the presence of an ABD (P = .003). The most frequent lesions were those with diameters between 2 and 4 mm (39.2%). There are only few studies on the prevalence of ABDs using CBCT analysis. This study in a French population shows a high prevalence of ABDs, especially on endodontically treated molars. The most effective way to exhaustively detect such defects is with CBCT imaging. Moreover, CBCT images show details of the extent of bone loss, thus providing information valuable for the therapeutic decision and details that could help with the prognosis

  12. Bloch-Wave Engineered Submicron Diameter Micropillars with Quality Factors Exceeding 10,000

    DEFF Research Database (Denmark)

    Hofling, S.; Lermer, M.; Gregersen, Niels

    2011-01-01

    Adiabatic design submicron diameter quantum-dot micropillars have been designed and implemented for cavity quantum electrodynamics experiments. Ultra-high experimental quality factors (>10,000) are obtained for submicron diameters and strong light-matter interaction is observed.......Adiabatic design submicron diameter quantum-dot micropillars have been designed and implemented for cavity quantum electrodynamics experiments. Ultra-high experimental quality factors (>10,000) are obtained for submicron diameters and strong light-matter interaction is observed....

  13. Factors influencing the perceived quality of clinical supervision of occupational therapists in a large Australian state.

    Science.gov (United States)

    Martin, Priya; Kumar, Saravana; Lizarondo, Lucylynn; Tyack, Zephanie

    2016-10-01

    Clinical supervision is important for effective health service delivery, professional development and practice. Despite its importance there is a lack of evidence regarding the factors that improve its quality. This study aimed to investigate the factors that influence the quality of clinical supervision of occupational therapists employed in a large public sector health service covering mental health, paediatrics, adult physical and other practice areas. A mixed method, sequential explanatory study design was used consisting of two phases. This article reports the quantitative phase (Phase One) which involved administration of the Manchester Clinical Supervision Scale (MCSS-26) to 207 occupational therapists. Frequency of supervision sessions, choice of supervisor and the type of supervision were found to be the predictor variables with a positive and significant influence on the quality of clinical supervision. Factors such as age, length of supervision and the area of practice were found to be the predictor variables with a negative and significant influence on the quality of clinical supervision. Factors that influence the perceived quality of clinical supervision among occupational therapists have been identified. High quality clinical supervision is an important component of clinical governance and has been shown to be beneficial to practitioners, patients and the organisation. Information on factors that make clinical supervision effective identified in this study can be added to existing supervision training and practices to improve the quality of clinical supervision. © 2016 Occupational Therapy Australia.

  14. Quality of life and its related factors in infertile couples.

    Science.gov (United States)

    Keramat, Afsaneh; Masoomi, Seyyedeh Zahra; Mousavi, Seyed Abbas; Poorolajal, Jalal; Shobeiri, Fatemeh; Hazavhei, Seyyed Mohammad Mehdi

    2014-01-01

    Health related quality of life (QoL) has now been considered as a main tool for outcome measurement in infertility. The present study aimed to determine the association between general and specified QoL with different psychological aspects of self-esteem, social support, sexual satisfaction, and marital satisfaction in a sample of Iranian infertile couples. This cross-sectional study was conducted on 385 infertile couples referred to the Fatemieh Hospital in Hamadan City, western Iran in 2012.To measure the self-esteem, the Iseng test was used. The social support scaling developed by Cassidy and Long was used for assessment of social support. The sexual satisfaction was also assessed by the Lindaberg questionnaire. For assessing the general QoL state, the WHO-QoL-BREF and FertiQoL tools were employed. Self-esteem scores were lower in the couples with longer infertility duration. The social support mean score was lower in low income couples. Those with higher educational level, shorter infertility duration, and higher income were more satisfied from their marital relationships. Besides, we revealed that the previous failed efforts for treatment of infertility were adversely associated with the lower social support and sexual satisfaction. The higher educational level, higher monthly income, living in urban area, shorter duration of marriage and infertility, and male gender were associated with better. QoL status in the most components.Associations between QoL and self-esteem, social support, sexual satisfaction, and marital satisfaction were significant (Pself-esteem, social support, sexual satisfaction, and marital satisfaction.

  15. Identifying items to assess methodological quality in physical therapy trials: a factor analysis.

    Science.gov (United States)

    Armijo-Olivo, Susan; Cummings, Greta G; Fuentes, Jorge; Saltaji, Humam; Ha, Christine; Chisholm, Annabritt; Pasichnyk, Dion; Rogers, Todd

    2014-09-01

    Numerous tools and individual items have been proposed to assess the methodological quality of randomized controlled trials (RCTs). The frequency of use of these items varies according to health area, which suggests a lack of agreement regarding their relevance to trial quality or risk of bias. The objectives of this study were: (1) to identify the underlying component structure of items and (2) to determine relevant items to evaluate the quality and risk of bias of trials in physical therapy by using an exploratory factor analysis (EFA). A methodological research design was used, and an EFA was performed. Randomized controlled trials used for this study were randomly selected from searches of the Cochrane Database of Systematic Reviews. Two reviewers used 45 items gathered from 7 different quality tools to assess the methodological quality of the RCTs. An exploratory factor analysis was conducted using the principal axis factoring (PAF) method followed by varimax rotation. Principal axis factoring identified 34 items loaded on 9 common factors: (1) selection bias; (2) performance and detection bias; (3) eligibility, intervention details, and description of outcome measures; (4) psychometric properties of the main outcome; (5) contamination and adherence to treatment; (6) attrition bias; (7) data analysis; (8) sample size; and (9) control and placebo adequacy. Because of the exploratory nature of the results, a confirmatory factor analysis is needed to validate this model. To the authors' knowledge, this is the first factor analysis to explore the underlying component items used to evaluate the methodological quality or risk of bias of RCTs in physical therapy. The items and factors represent a starting point for evaluating the methodological quality and risk of bias in physical therapy trials. Empirical evidence of the association among these items with treatment effects and a confirmatory factor analysis of these results are needed to validate these items.

  16. Factors Affecting Quality of Laboratory Services in Public and Private Health Facilities in Addis Ababa, Ethiopia

    Science.gov (United States)

    Taye, Binyam; Belay, Getachew; Ashenafi, Aytenew; Girma, Veronica

    2017-01-01

    Background Quality laboratory service is an essential component of health care system but in Sub-Saharan Africa such as Ethiopia, laboratories quality system remains weak due to several factors and it needs more attention to strengthen its capacity and quality system. Methodology A cross sectional study was conducted using a questionnaire to assess factors affecting the quality of laboratory service at private and public health institutions in Addis Ababa. Results A total of 213 laboratory professionals participated in the study and 131 (61.5%) participants had bachelor degree. Majority, 133 (62.4%), of the professionals did not attend any work related training. Seventy five (35.2%) respondents believed that their laboratories did not provide quality laboratory services and the major reported factors affecting provision of quality services were shortage of resources (64.3%), poor management support (57.3%), poor equipment quality (53.4%), high workload (41.1%), lack of equipment calibration (38.3%) and lack of knowledge (23.3%). Moreover logistic regression analysis showed that provision of quality laboratory service was significantly associated with result verification (AOR=9.21, 95% CI=2.26, 37.48), internal quality control (AOR= 6.11, 95% CI=2.11, 17.70), turnaround time (AOR=5.11, 95% CI=1.94, 13.46), shortage of equipment (AOR=7.76, 95% CI=2.55, 23.66), communication with clinicians (AOR=3.24, 95% CI=1.25, 8.41) and lack of job description (AOR=3.67, 95% CI=1.319, 10.22). Conclusion In conclusion, the major factors that affecting the quality of laboratory service were associated with poor human resource management, poor resources provision, poor management commitment, ineffective communication system and lack of well-established quality management system. PMID:29075171

  17. Factors Affecting Quality of Laboratory Services in Public and Private Health Facilities in Addis Ababa, Ethiopia.

    Science.gov (United States)

    Mesfin, Eyob Abera; Taye, Binyam; Belay, Getachew; Ashenafi, Aytenew; Girma, Veronica

    2017-10-01

    Quality laboratory service is an essential component of health care system but in Sub-Saharan Africa such as Ethiopia, laboratories quality system remains weak due to several factors and it needs more attention to strengthen its capacity and quality system. A cross sectional study was conducted using a questionnaire to assess factors affecting the quality of laboratory service at private and public health institutions in Addis Ababa. A total of 213 laboratory professionals participated in the study and 131 (61.5%) participants had bachelor degree. Majority, 133 (62.4%), of the professionals did not attend any work related training. Seventy five (35.2%) respondents believed that their laboratories did not provide quality laboratory services and the major reported factors affecting provision of quality services were shortage of resources (64.3%), poor management support (57.3%), poor equipment quality (53.4%), high workload (41.1%), lack of equipment calibration (38.3%) and lack of knowledge (23.3%). Moreover logistic regression analysis showed that provision of quality laboratory service was significantly associated with result verification (AOR=9.21, 95% CI=2.26, 37.48), internal quality control (AOR= 6.11, 95% CI=2.11, 17.70), turnaround time (AOR=5.11, 95% CI=1.94, 13.46), shortage of equipment (AOR=7.76, 95% CI=2.55, 23.66), communication with clinicians (AOR=3.24, 95% CI=1.25, 8.41) and lack of job description (AOR=3.67, 95% CI=1.319, 10.22). In conclusion, the major factors that affecting the quality of laboratory service were associated with poor human resource management, poor resources provision, poor management commitment, ineffective communication system and lack of well-established quality management system.

  18. Factors controlling air quality in different European subway systems.

    Science.gov (United States)

    Martins, Vânia; Moreno, Teresa; Mendes, Luís; Eleftheriadis, Konstantinos; Diapouli, Evangelia; Alves, Célia A; Duarte, Márcio; de Miguel, Eladio; Capdevila, Marta; Querol, Xavier; Minguillón, María Cruz

    2016-04-01

    Sampling campaigns using the same equipment and methodology were conducted to assess and compare the air quality at three South European subway systems (Barcelona, Athens and Oporto), focusing on concentrations and chemical composition of PM2.5 on subway platforms, as well as PM2.5 concentrations inside trains. Experimental results showed that the mean PM2.5 concentrations widely varied among the European subway systems, and even among different platforms within the same underground system, which might be associated to distinct station and tunnel designs and ventilation systems. In all cases PM2.5 concentrations on the platforms were higher than those in the urban ambient air, evidencing that there is generation of PM2.5 associated with the subway systems operation. Subway PM2.5 consisted of elemental iron, total carbon, crustal matter, secondary inorganic compounds, insoluble sulphate, halite and trace elements. Of all metals, Fe was the most abundant, accounting for 29-43% of the total PM2.5 mass (41-61% if Fe2O3 is considered), indicating the existence of an Fe source in the subway system, which could have its origin in mechanical friction and wear processes between rails, wheels and brakes. The trace elements with the highest enrichment in the subway PM2.5 were Ba, Cu, Mn, Zn, Cr, Sb, Sr, Ni, Sn, Co, Zr and Mo. Similar PM2.5 diurnal trends were observed on platforms from different subway systems, with higher concentrations during subway operating hours than during the transport service interruption, and lower levels on weekends than on weekdays. PM2.5 concentrations depended largely on the operation and frequency of the trains and the ventilation system, and were lower inside the trains, when air conditioning system was operating properly, than on the platforms. However, the PM2.5 concentrations increased considerably when the train windows were open. The PM2.5 levels inside the trains decreased with the trains passage in aboveground sections. Copyright © 2015

  19. Impact of age on quality of life in patients with localized prostate cancer treated with high-dose rate brachytherapy combined with external beam radiotherapy.

    Science.gov (United States)

    Kikkawa, Kazuro; Iba, Akinori; Kohjimoto, Yasuo; Noda, Yasutaka; Sonomura, Tetsuo; Hara, Isao

    2018-02-04

    To evaluate age-related quality of life changes in patients with localized prostate cancer treated by high-dose rate brachytherapy combined with external beam radiation therapy. A total of 172 patients with clinically localized prostate cancer were categorized to age groups <75 years and ≥75 years. Changes in their quality of life were evaluated using the Japanese version of Medical Outcome Study 8-Items Short Form Health Survey, Expanded Prostate Cancer Index Composite and International Index of Erectile Function-5 at baseline, and followed up to 24 months after treatment. There were no significant differences in Medical Outcome Study 8-Items Short Form Health Survey scores, and urinary and bowel scores of the Expanded Prostate Cancer Index Composite for older men after treatment. International Index of Erectile Function-5 summary scores were significantly decreased in both groups. Although sexual function and sexual bother scores were decreased in patients aged <75 years, these scores were maintained in patients aged ≥75 years. Quality of life of prostate cancer patients undergoing high-dose rate brachytherapy combined with external beam radiation therapy does not seem to be significantly affected by age. © 2018 The Japanese Urological Association.

  20. Factors of Quality Improvement of the Foreign Language Teaching in Technical University

    Directory of Open Access Journals (Sweden)

    Ira R. Agasieva

    2017-03-01

    Full Text Available In the article the problem of quality of teaching and knowledge of the English language has been considered. The factors that influence the improvement of the quality of teaching and knowledge of the English language in a technical college, the use of various methods of enhancing the quality of teaching and knowledge of the English language has been analyzed. It has been distinguished the necessity of taking into account the factors such as emotional maturity of the student, the desire for success, student cognitive style, its consistency and independence.