WorldWideScience

Sample records for field dosimetry utilizing

  1. Dosimetry in clinical static magnetic fields using plastic scintillation detectors

    DEFF Research Database (Denmark)

    Stefanowicz, S.; Latzel, H.; Lindvold, Lars René

    2013-01-01

    , however, not clear yet how dosimetry will be conducted as standard methods and might not be easily transferred to systems with clinical magnetic fields. For dosimetry in MRI accelerators, we have tested plastic scintillation detectors (PSD) coupled to optical fibers. They are suitable for real-time and in......-vivo dosimetry in radiation treatments and diagnostics and could be, being all-optical, promising candidates for this application. To study the basic feasibility of using PSDs with organic scintillators in magnetic fields, we measured the response of these dosimeters in presence of magnetic fields up to 1 T...

  2. The clinical utility of vocal dosimetry for assessing voice rest.

    Science.gov (United States)

    Misono, Stephanie; Banks, Kathryn; Gaillard, Philippe; Goding, George S; Yueh, Bevan

    2015-01-01

    Voice rest is frequently recommended following surgical disruption of vocal fold epithelium, but patients report variable adherence to voice rest recommendations. The objective of this study was to assess the clinical utility of an ambulatory vocal dosimeter for measuring adherence to voice rest recommendations. Outcomes research. Part 1: To determine the utility of the dosimeter in nonclinical use, the relationship between self-reported voice use and dosimeter measurements was examined in normal subjects (n = 11) who prospectively logged voice use while wearing the dosimeter. Part 2: To determine clinical utility of the dosimeter, patients undergoing vocal fold surgery for which postoperative voice rest was recommended (n = 11) wore a dosimeter for 2 days prior to and 2 days after surgery. Phonation percent and sound level were compared at baseline and during voice rest. The dosimeter performed as hypothesized with both normal subjects and patients. A moderate correlation (r = 0.62) was noted between self-reported voice use and dosimeter measurements in normal subjects. In patients on voice rest, a statistically and clinically significant decrease was observed in measured voice use, both in phonation time (P = .002) and intensity of phonation (P = .004). Ambulatory vocal dosimetry may have clinical utility for assessing adherence to voice rest recommendations. This information will be useful for the design of future studies on voice rest. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

  3. MO-D-BRD-02: In Memoriam of Bengt Bjarngard: SBRT II: Small Field Dosimetry - TG155

    Energy Technology Data Exchange (ETDEWEB)

    Das, I [Indiana University- School of Medicine, Indianapolis, IN (United States); Reft, C [University Chicago, Chicago, IL (United States)

    2014-06-15

    Specialized radiation treatment such as SRS/SRT. SBRT, IMRT, VMAT, Tomotherapy, CyberKnife and Gamma Knife use small fields or combination of small fields where dosimetry is challenging and uncertain due to non-equilibrium conditions such as longitudinal and lateral disequilibrium. Additionally the primary photon fluence is greatly affected by the obstruction of the source size by the jaws creating a large dose gradient across the field. Electronic equilibrium is a phenomenon associated with the range of secondary particles which depend on the beam energy, photon spectrum and the composition of the medium. Additionally, the finite size of detectors creates volume averaging and fluence perturbations especially in small fields. The IAEA/AAPM has provided a frame work for non-compliant reference dosimetry in small fields1. The AAPM TG-1552 has adopted this frame work to provide guidelines in relative dosimetry. This course provides the insight of TG-155 that defines small field, provides recommendations for suitable detectors and associated correction factors to convert reading to dose. Recommendations of a good working practice for relative dosimetry measurements (PDD, TMR, output factor, etc.) and dose calculations based on the new formulation is are elaborated. It also discusses beam modeling and dose calculations as a critical step in clinical utilization of small field radiotherapy. Small errors in beam data, approximations in dose algorithms, or misaligned of detectors and field settings can propagate into large errors in planned and delivered dose. The modeling and treatment planning aspects of small field dosimetry are reviewed with emphasis on the most critical parts for ensuring accurate and safe radiation therapy. Discussion on k(fmsr, fclin) for commercially available detectors are also provided.1 P. Alfonso, P. Andreo, R. Capote, M. S. Huq, W. Kilby, P. Kjall, T. R. Mackie, H. Palmans, K. Rosser, J. Seuntjens, W. Ullrich and S. Vatnitsky, “A new

  4. Advances in electron dosimetry of irregular fields; Avances en dosimetria de electrones de campos irregulares

    Energy Technology Data Exchange (ETDEWEB)

    Mendez V, J. [Departamento de Radioterapia, Instituto de Enfermedades Neoplasicas, Avenida Angamos Este 2520, Lima 34 (Peru)

    1998-12-31

    In this work it is presented an advance in Electron dosimetry of irregular fields for beams emitted by linear accelerators. At present diverse methods exist which are coming to apply in the Radiotherapy centers. In this work it is proposed a method for irregular fields dosimetry. It will be allow to calculate the dose rate absorbed required for evaluating the time for the treatment of cancer patients. Utilizing the results obtained by the dosimetric system, it has been possible to prove the validity of the method describe for 12 MeV energy and for square field 7.5 x 7.5 cm{sup 2} with percentile error less than 1 % . (Author)

  5. DOSIMETRY

    CERN Multimedia

    Service de dosimétrie individuelle

    2000-01-01

    From the distribution Novembre/Decembre 2000 (film colour green), the people who worked in LEP experiments and who have not announced their participation to LEP dismantling or new activities in another experiment or group will be taken out from the regular distribution list of the Individual Dosimetry Service. Please contact Individual Dosimetry Service, tel. 72155 or e-mail to Jeannine.Fraisse@cern.ch We inform all staff and users under regular dosimetric control that the dosimeters for the monitoring period SEPTEMBER/OCTOBER will be available from their usual dispatchers on the 1st of September 2000. Please have your films changed before the 12th of September. The colour of the dosimeter valid in SEPTEMBER/OCTOBER is RED. The service will be closed exceptionally on Friday 8 September.

  6. DOSIMETRY

    CERN Multimedia

    2001-01-01

    From the month of May on, the neutron dosimeter will be worn in an extra package distinct from the usual film-badge. We will give you more ample information in Weekly Bulletin No. 18/2001 of April 30, 2001. In the week following Easter (17 - 20. 4. 2001) the Individual Dosimetry Service will be opened in the mornings from 8:30 to 11:30 h only. The Service will be closed on April 30.

  7. Dosimetry in radiation fields around high-energy proton accelerators

    CERN Document Server

    Agosteo, S; Silari, M; Theis, C

    2008-01-01

    Radiation dosimetry at high-energy proton accelerators is a difficult task because of the complexity of the stray radiation field. A good knowledge of this mixed radiation field is very important to be able to select the type of detectors (active and/or passive) to be employed for routine area monitoring and to choose the personal dosimeter legally required for estimating the effective dose received by individuals. At the same time, the response function of the detectors to the mixed field must be thoroughly understood. A proper calibration of a device, which may involve a complex series of measurements in various reference fields, is needed. Monte Carlo simulations provide a complementary – and sometimes the principal – mean of determining the response function. The ambient dose equivalent rates during operation range from a few hundreds of μSv per year to a few mSv per year. To measure such rates one needs detectors of high sensitivity and/or capable of integrating over long periods. The main challenge...

  8. Reference dosimetry and small-field dosimetry in external beam radiotherapy: Results from a Danish intercomparison study

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Behrens, Claus F.; Sibolt, Patrik

    methods was performed by DTU Nutech at six Danish clinics. The first part of the intercompa-rison regarded the consistency of reference dosimetry. Absorbed dose to water under reference conditions was measured using a Farmer ionization chamber, and was found to agree within 1 % with the daily dose checks......-mators and the measured field sizes, although one clinic showed field dimensions that were down to 21 ± 3 % smaller than expected. Small-field correction factors were estimated for a PinPoint cham-ber and a diamond detector using a fibre-coupled organic scintilla-tor as reference, after correcting for volume averaging...

  9. Use of Neutron Benchmark Fields for the Validation of Dosimetry Cross Sections

    Directory of Open Access Journals (Sweden)

    Griffin Patrick

    2016-01-01

    Full Text Available The evolution of validation metrics for dosimetry cross sections in neutron benchmark fields is explored. The strength of some of the metrics in providing validation evidence is examined by applying them to the 252Cf spontaneous fission standard neutron benchmark field, the 235U thermal neutron fission reference benchmark field, the ACRR pool-type reactor central cavity reference benchmark fields, and the SPR-III fast burst reactor central cavity. The IRDFF dosimetry cross section library is used in the validation study and observations are made on the amount of coverage provided to the library contents by validation data available in these benchmark fields.

  10. Dosimetry of the mixed field irradiation facility CALIBAN

    Energy Technology Data Exchange (ETDEWEB)

    Trompier, F. [Institute for Radiological Protection and Nuclear Safety, 92265 Fontenay-aux-roses (France)], E-mail: francois.trompier@irsn.fr; Huet, C.; Medioni, R.; Robbes, I. [Institute for Radiological Protection and Nuclear Safety, 92265 Fontenay-aux-roses (France); Asselineau, B. [Institute of Radioprotection and Nuclear Safety, 13115 St Paul-Lez-Durance (France)

    2008-02-15

    The dosimetry of the experimental reactor CALIBAN was established for photon and neutron components, and the kerma variations were evaluated according to position (distance from the core, height, angle with the median room axis). Dosimetry was performed with TLD (Al{sub 2}O{sub 3}) for the photon component, and with passive silicon diodes, activation detectors (Au, In, Ni, Mg, Cu) and alanine pellets measured by EPR spectrometry for the neutron component. The neutron energy distribution was experimentally evaluated at various distances based on the activities measured at the activated foil using the SNAC2 software. It was then compared with those calculated with the Monte Carlo code MCNPX.

  11. Time resolved dosimetry of human brain exposed to low frequency pulsed magnetic fields

    Science.gov (United States)

    Paffi, Alessandra; Camera, Francesca; Lucano, Elena; Apollonio, Francesca; Liberti, Micaela

    2016-06-01

    An accurate dosimetry is a key issue to understanding brain stimulation and related interaction mechanisms with neuronal tissues at the basis of the increasing amount of literature revealing the effects on human brain induced by low-level, low frequency pulsed magnetic fields (PMFs). Most literature on brain dosimetry estimates the maximum E field value reached inside the tissue without considering its time pattern or tissue dispersivity. Nevertheless a time-resolved dosimetry, accounting for dispersive tissues behavior, becomes necessary considering that the threshold for an effect onset may vary depending on the pulse waveform and that tissues may filter the applied stimulatory fields altering the predicted stimulatory waveform’s size and shape. In this paper a time-resolved dosimetry has been applied on a realistic brain model exposed to the signal presented in Capone et al (2009 J. Neural Transm. 116 257-65), accounting for the broadband dispersivity of brain tissues up to several kHz, to accurately reconstruct electric field and current density waveforms inside different brain tissues. The results obtained by exposing the Duke’s brain model to this PMF signal show that the E peak in the brain is considerably underestimated if a simple monochromatic dosimetry is carried out at the pulse repetition frequency of 75 Hz.

  12. A new formalism for reference dosimetry of small and nonstandard fields.

    Science.gov (United States)

    Alfonso, R; Andreo, P; Capote, R; Huq, M Saiful; Kilby, W; Kjäll, P; Mackie, T R; Palmans, H; Rosser, K; Seuntjens, J; Ullrich, W; Vatnitsky, S

    2008-11-01

    The use of small fields in radiotherapy techniques has increased substantially, in particular in stereotactic treatments and large uniform or nonuniform fields that are composed of small fields such as for intensity modulated radiation therapy (IMRT). This has been facilitated by the increased availability of standard and add-on multileaf collimators and a variety of new treatment units. For these fields, dosimetric errors have become considerably larger than in conventional beams mostly due to two reasons; (i) the reference conditions recommended by conventional Codes of Practice (CoPs) cannot be established in some machines and (ii) the measurement of absorbed dose to water in composite fields is not standardized. In order to develop standardized recommendations for dosimetry procedures and detectors, an international working group on reference dosimetry of small and nonstandard fields has been established by the International Atomic Energy Agency (IAEA) in cooperation with the American Association of Physicists in Medicine (AAPM) Therapy Physics Committee. This paper outlines a new formalism for the dosimetry of small and composite fields with the intention to extend recommendations given in conventional CoPs for clinical reference dosimetry based on absorbed dose to water. This formalism introduces the concept of two new intermediate calibration fields: (i) a static machine-specific reference field for those modalities that cannot establish conventional reference conditions and (ii) a plan-class specific reference field closer to the patient-specific clinical fields thereby facilitating standardization of composite field dosimetry. Prior to progressing with developing a CoP or other form of recommendation, the members of this IAEA working group welcome comments from the international medical physics community on the formalism presented here.

  13. A Quality Assurance Method that Utilizes 3D Dosimetry and Facilitates Clinical Interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Oldham, Mark, E-mail: mark.oldham@duke.edu [Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Thomas, Andrew; O' Daniel, Jennifer; Juang, Titania [Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Ibbott, Geoffrey [University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Adamovics, John [Rider University, Lawrenceville, New Jersey (United States); Kirkpatrick, John P. [Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2012-10-01

    Purpose: To demonstrate a new three-dimensional (3D) quality assurance (QA) method that provides comprehensive dosimetry verification and facilitates evaluation of the clinical significance of QA data acquired in a phantom. Also to apply the method to investigate the dosimetric efficacy of base-of-skull (BOS) intensity-modulated radiotherapy (IMRT) treatment. Methods and Materials: Two types of IMRT QA verification plans were created for 6 patients who received BOS IMRT. The first plan enabled conventional 2D planar IMRT QA using the Varian portal dosimetry system. The second plan enabled 3D verification using an anthropomorphic head phantom. In the latter, the 3D dose distribution was measured using the DLOS/Presage dosimetry system (DLOS = Duke Large-field-of-view Optical-CT System, Presage Heuris Pharma, Skillman, NJ), which yielded isotropic 2-mm data throughout the treated volume. In a novel step, measured 3D dose distributions were transformed back to the patient's CT to enable calculation of dose-volume histograms (DVH) and dose overlays. Measured and planned patient DVHs were compared to investigate clinical significance. Results: Close agreement between measured and calculated dose distributions was observed for all 6 cases. For gamma criteria of 3%, 2 mm, the mean passing rate for portal dosimetry was 96.8% (range, 92.0%-98.9%), compared to 94.9% (range, 90.1%-98.9%) for 3D. There was no clear correlation between 2D and 3D passing rates. Planned and measured dose distributions were evaluated on the patient's anatomy, using DVH and dose overlays. Minor deviations were detected, and the clinical significance of these are presented and discussed. Conclusions: Two advantages accrue to the methods presented here. First, treatment accuracy is evaluated throughout the whole treated volume, yielding comprehensive verification. Second, the clinical significance of any deviations can be assessed through the generation of DVH curves and dose overlays on

  14. Toward acquiring comprehensive radiosurgery field commissioning data using the PRESAGE/optical-CT 3D dosimetry system

    Energy Technology Data Exchange (ETDEWEB)

    Clift, Corey; Thomas, Andrew; Chang Zheng; Oldham, Mark [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Adamovics, John [Department of Chemistry, Rider University, Lawrenceville, NJ 08648 (United States); Das, Indra [Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN 46202 (United States)], E-mail: cclift@montefiore.org

    2010-03-07

    Achieving accurate small field dosimetry is challenging. This study investigates the utility of a radiochromic plastic PRESAGE read with optical-CT for the acquisition of radiosurgery field commissioning data from a Novalis Tx system with a high-definition multileaf collimator (HDMLC). Total scatter factors (S{sub c,p}), beam profiles, and penumbrae were measured for five different radiosurgery fields (5, 10, 20, 30 and 40 mm) using a commercially available optical-CT scanner (OCTOPUS, MGS Research). The percent depth dose (PDD), beam profile and penumbra of the 10 mm field were also measured using a higher resolution in-house prototype CCD-based scanner. Gafchromic EBT film was used for independent verification. Measurements of S{sub c,p} made with PRESAGE and film agreed with mini-ion chamber commissioning data to within 4% for every field (range 0.2-3.6% for PRESAGE, and 1.6-3.6% for EBT). PDD, beam profile and penumbra measurements made with the two PRESAGE/optical-CT systems and film showed good agreement with the high-resolution diode commissioning measurements with a competitive resolution (0.5 mm pixels). The in-house prototype optical-CT scanner allowed much finer resolution compared with previous applications of PRESAGE. The advantages of the PRESAGE (registered) system for small field dosimetry include 3D measurements, negligible volume averaging, directional insensitivity, an absence of beam perturbations, energy and dose rate independence.

  15. Poster - Thur Eve - 46: The upcoming international code of practice for small static photon field dosimetry.

    Science.gov (United States)

    Palmans, H; Alfonso, R; Andreo, P; Capote, R; Huq, M S; Izewska, J; Johansson, J; Kilby, W; Mackie, T R; Meghzifene, A; Rosser, K; Seuntjens, J; Ullrich, W

    2012-07-01

    The increased use of small photon fields in stereotactic and intensity-modulated radiotherapy has raised the need for standardizing the dosimetry of such fields using procedures consistent with those for conventional radiotherapy. An international working group, established by the IAEA in collaboration with AAPM and IPEM, is finalising a Code of Practice for the dosimetry of small static photon fields. Procedures for reference dosimetry in nonstandard machine specific reference (msr) fields are provided following the formalism of Alfonso et al. (Med. Phys. 35: 5179; 2008). Reference dosimetry using ionization chambers in machines that cannot establish a conventional 10 cm × 10 cm reference field is based on either a direct calibration in the msr field traceable to primary standards, a calibration in a reference field and a generic correction factor or the product of a correction factor for a virtual reference field and a correction factor for the difference between the msr and virtual fields. For the latter method, procedures are provided for determining the beam quality in non-reference conditions. For the measurement of field output factors in small fields, procedures for connecting large field measurements using ionization chambers to small field measurements using high-resolution detectors such as diodes, diamond, liquid ion chambers, organic scintillators and radiochromic film are given. The Code of Practice also presents consensus data on correction factors for use in conjunction with measured, detector-specific output factors. Further research to determine missing data according to the proposed framework will be strongly encouraged by publication of this document. © 2012 American Association of Physicists in Medicine.

  16. Dosimetry methods

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, A.; Kovacs, A.;

    2003-01-01

    Chemical and physical radiation dosimetry methods, used for the measurement of absorbed dose mainly during the practical use of ionizing radiation, are discussed with respect to their characteristics and fields of application.......Chemical and physical radiation dosimetry methods, used for the measurement of absorbed dose mainly during the practical use of ionizing radiation, are discussed with respect to their characteristics and fields of application....

  17. Study of homogeneity and inhomogeneity phantom in CUDA EGS for small field dosimetry

    Science.gov (United States)

    Yani, Sitti; Rhani, Mohamad Fahdillah; Haryanto, Freddy; Arif, Idam

    2017-02-01

    CUDA EGS was CUDA implementation to simulate transport photon in a material based on Monte Carlo algorithm for X-ray imaging. The objective of this study was to investigate the effect of inhomogeneities in inhomogeneity phantom for small field dosimetry (1×1, 2×2, 3×3, 4×4 and 5×5 cm2). Two phantoms, homogeneity and inhomogeneity phantom were used. The interaction in homogeneity and inhomogeneity phantom was dominated by Compton interaction and multiple scattering. The CUDA EGS can represent the inhomogeneity effect in small field dosimetry by combining the grayscale curve between homogeneity and inhomogeneity phantom. The grayscale curve in inhomogeneity phantom is not asymmetric because of the existence of different material in phantom.

  18. Dosimetry and field matching for radiotherapy to the breast and superclavicular fossa

    Science.gov (United States)

    Winfield, Elizabeth

    Radiotherapy for early breast cancer aims to achieve local disease control and decrease loco-regional recurrence rates. Treatment may be directed to breast or chest wall alone or, include regional lymph nodes. When using tangential fields to treat the breast a separate anterior field directed to the axilla and supraclavicular fossa (SCF) is needed to treat nodal areas. The complex geometry of this region necessitates matching of adjacent radiation fields in three dimensions. The potential exists for zones of overdosage or underdosage along the match line. Cosmetic results may be compromised if treatment fields are not accurately aligned. Techniques for field matching vary between centres in the UK. A study of dosimetry across the match line region using different techniques, as reported in the multi-centre START Trial Quality Assurance (QA) programme, was undertaken. A custom-made anthropomorphic phantom was designed to assess dose distribution in three dimensions using film dosimetry. Methods with varying degrees of complexity were employed to match tangential and SCF beams. Various techniques combined half beam blocking and machine rotations to achieve geometric alignment. Matching of asymmetric beams allowed a single isocentre technique to be used. Where field matching was not undertaken a gap between tangential and SCF fields was employed. Results demonstrated differences between techniques in addition to variations within the same technique between different centres. Geometric alignment techniques produced more homogenous dose distributions in the match region than gap techniques or those techniques not correcting for field divergence. For this multi-centre assessment of match plane techniques film dosimetry used in conjunction with a breast shaped phantom provided relative dose information. This study has highlighted the difficulties of matching treatment fields to achieve homogenous dose distribution through the region of the match plane and the degree of

  19. Scientific days on electromagnetic fields: from dosimetry to human health - Conference proceedings; Journees scientifiques - Champs electromagnetiques: de la dosimetrie a la sante humaine - Recueil des resumes et presentations

    Energy Technology Data Exchange (ETDEWEB)

    Wiart, J.; Ghanmi, A.; Picon, O.; Conil, E.; Varsier, N.; Hadjem, A.; Sudret, B.; Magne, I.; Souques, M.; Gaudaire, F.; De Seze, R.; Jawad, O.; Lautru, D.; Dricot, J.M.; Horlin, F.; De Doncker, P.; Drissaoui, A.; Musy, F.; Nicolas, L.; Perrussel, R.; Scorretti, R.; Voyer, D.; Jala, M.; Moulines, E.; Levy-Leduc, C.; Mahfouz, Z.; Gati, A.; Fouad Hanna, V.; Leveque, P.; Arnaud-Cormos, D.; Zhadobov, M.; Jarrige, P.; Gaborit, G.; Kohler, S.; Ticaud, N.; Duvillaret, L.; Guelilia, Z.; Loison, R.; Gillard, R.; Laisne, A.; Favet, D.; Benadhira, R.; Mir, L.; Nadi, M.; Kourtiche, D.; Gazeau, F.; Wilhelm, C.; Delemotte, L.; Breton, M.; Tarek, M.; Marc-Vergnes, J.P.; Yardin, C.; Perrin, A.; Le Drean, Y.; Sauleau, R.; Lambrozo, J.; Selmaoui, B.; Ghosn, R.; Thuroczy, G.; Villegier, A.S.; Loos, N.; Brenet-Dufour, V.; Liabeuf, S.; Bach, V.; Moretti, D.; Lewis, N.; Garenne, A.; Poulletier De Gannes, F.; Haro, E.; Lagroye, I.; Bornat, Y.; Boutaib, Y.; Saighi, S.; Renaud, S.; Veyre, B.; Schuz, J.; Deltour, I.; Van Deventer, E.; Vecchia, P.; Merckel, O.; Bellaouel, A.; Demaret, P.; Donati, P.; Jovanovic, D.; Chauvin, S.; Desreumaux, J.P.; Fouquet, L.; Picard, D.; Massardier-Pilonchery, A.; Hours, M.; Bergeret, A.; Person, C.; Toutain, Y.; Butet, R.; Berrahma, K.; Balderelli, I.; Stelmaszyk, V.; Cretallaz, C.; Lamproglou, I.; Amourette, C.; Diserbo, M.; Fauquette, W.; Martigne, P.; Collin, A.; Lagroye, I.; Ait Aissa, S.; Hurtier, A.; Taxile, M.; Le Montagner, L.; Athane, A.; Duleu, S.; Percherancier, Y.; Geffard, M.; Ruffie, G.; Billaudel, B.; Veyret, B.; Pelletier, A.; Delanaud, S.; Libert, J.P.; Schunck, T.; Bieth, F.; Soubere Mahamoud, Y.; Le Quement, C.; Ferrand, G.; Le Guevel, R.; Carton, P.H.; Luong, M.; Tanvir, S.; Selmaoui, B.; Silva Pires-Antonietti, V.; Sonnet, P.; Pulvin, S.; Kuster, O.; Tetelin, C.

    2012-04-15

    This document brings together the available presentations (articles and slides) given at the URSI scientific days on electromagnetic fields: dosimetry, peoples' exposure, biological and health risks, risk management, and medical uses. 48 presentations are compiled in this document and deal with: 1 - Stochastic dosimetry: variability challenge; 2 - How to estimate the exposure to 50/60 Hz magnetic field in an epidemiological study?; 3 - Joint analysis of population exposure and radio coverage of GSM and UMTS mobile phone networks; 4 - Study of the specific energy absorption rate (SAR) sensitiveness to phone positions near the head for 2 GSM mobile phones; 5 - Statistical Study of SAR under Wireless Channel - Exposure in Indoor Environment; 6 - Uncertainty propagation in numerical dosimetry: how to reduce calculation costs?; 7 - Use of a simplified pregnant woman model for foetus exposure analysis; 8 - SAR estimation using multi-exposure with a mobile phone; 9 - State-of-the-art in experimental dosimetry (RF and pulses); 10 - Mm-waves dosimetry: issues, stakes and actual solutions; 11 - Use of DG-FDTD for a dosimetry calculation in a strongly multi-scale problem: determination of the eye-SAR near a HF/VHF vehicle-borne source; 12 - Dosimetric measurements with a fiber-type electro-optical sensor; 13 - Partial experimental evaluation of basic restrictions in the HF/VHF range; 14 - Repetitive trans-cranial magnetic stimulation Stimulation (rTMS) in psychiatry: present day situation and perspectives; 15 - Medical applications of electric fields; 16 - Measurements for life: new perspectives? 17 - Nano-particles and magnetic stimuli for medical imaging and therapy; 18 - Molecular Insights into electroporation and siRNA electro-transfer through model cell membranes; 19 - State of knowledge on electromagnetic fields hypersensitivity (HS-CEM); 20 - Experimentation methodology: from results to interpretation; 22 - Mm waves - update on biological effects at 40-60 GHz; 23

  20. Small-Field Dosimetry in A 6 MV Photon Beam Using Alanine and Liquid Ionisation Chamber

    DEFF Research Database (Denmark)

    Zimmermann, S.; Riis, H. L.; Hjelm-Hansen, M.

    2012-01-01

    Lion ionisation chamber for small-field dosimetry in liquid water. Materials and Methods: The measurements were carried out on a Siemens Primus 58 leaves MLC. The alanine dosimeters were cylindric Ø4.9 mm × 3.0 mm and density of 1.2 g/cm3. The alanine dosimeters were placed on the top of a solid water stick of Ø4......, 2 times 4 sweeps with a 90° turn in between, total measurement time was 3 minutes per dosimeter. The alanine dosimetry system was calibrated using a Co60 gamma cell ensuring traceability to a national standard. Results: The results are summarized in Table 1. At depths below 2 mm, we noted...

  1. Topics in radiation dosimetry radiation dosimetry

    CERN Document Server

    1972-01-01

    Radiation Dosimetry, Supplement 1: Topics in Radiation Dosimetry covers instruments and techniques in dealing with special dosimetry problems. The book discusses thermoluminescence dosimetry in archeological dating; dosimetric applications of track etching; vacuum chambers of radiation measurement. The text also describes wall-less detectors in microdosimetry; dosimetry of low-energy X-rays; and the theory and general applicability of the gamma-ray theory of track effects to various systems. Dose equivalent determinations in neutron fields by means of moderator techniques; as well as developm

  2. Characterization of TLD-100 micro-cubes for use in small field dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Peña-Jiménez, Salvador, E-mail: zoid-9861@yahoo.com.mx; Gamboa-deBuen, Isabel, E-mail: gamboa@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Av. Universidad 3000, 04510 DF (Mexico); Lárraga-Gutiérrez, José Manuel, E-mail: jose.larraga.gtz@gmail.com, E-mail: amanda.garcia.g@gmail.com; García-Garduño, Olivia Amanda, E-mail: jose.larraga.gtz@gmail.com, E-mail: amanda.garcia.g@gmail.com [Laboratorio de Física Médica, Instituto Nacional de Neurología y Neurocirugía Manuel Velasco Suárez, Av. Insurgentes Sur 3877, 14269 DF (Mexico)

    2014-11-07

    At present there are no international regulations for the management of millimeter scale fields and there are no suggestions for a reference detector to perform the characterization and dose determination for unconventional radiation beams (small fields) so that the dosimetry of small fields remains an open research field worldwide because these fields are used in radiotherapy treatments. Sensitivity factors and reproducibility of TLD-100 micro-cubes (1×1×1 mm3) were determinate irradiating the dosimeters with a 6 MV beam in a linear accelerator dedicated to radiosurgery at the Instituto Nacional de Neurología y Neurocirugía (INNN). Thermoluminescent response as a function of dose was determined for doses in water between 0.5 and 3 Gy and two field sizes (2×2 cm2 and 10×10 cm2). It was found that the response is linear over the dose range studied and it does not depend on field size.

  3. Advanced radiochromic film methodologies for quantitative dosimetry of small and nonstandard fields

    Science.gov (United States)

    Rosen, Benjamin S.

    Radiotherapy treatments with small and nonstandard fields are increasing in use as collimation and targeting become more advanced, which spare normal tissues while increasing tumor dose. However, dosimetry of small and nonstandard fields is more difficult than that of conventional fields due to loss of lateral charged-particle equilibrium, tight measurement setup requirements, source occlusion, and the volume-averaging effect of conventional dosimeters. This work aims to create new small and nonstandard field dosimetry protocols using radiochromic film (RCF) in conjunction with novel readout and analysis methodologies. It also is the intent of this work to develop an improved understanding of RCF structure and mechanics for its quantitative use in general applications. Conventional digitization techniques employ white-light, flatbed document scanners or scanning-laser densitometers which are not optimized for RCF dosimetry. A point-by-point precision laser densitometry system (LDS) was developed for this work to overcome the film-scanning artifacts associated with the use of conventional digitizers, such as positional scan dependence, off-axis light scatter, glass bed interference, and low signal-to-noise ratios. The LDS was shown to be optically traceable to national standards and to provide highly reproducible density measurements. Use of the LDS resulted in increased agreement between RCF dose measurements and the single-hit detector model of film response, facilitating traceable RCF calibrations based on calibrated physical quantities. GafchromicRTM EBT3 energy response to a variety of reference x-ray and gamma-ray beam qualities was also investigated. Conventional Monte Carlo methods are not capable of predicting film intrinsic energy response to arbitrary particle spectra. Therefore, a microdosimetric model was developed to simulate the underlying physics of the radiochromic mechanism and was shown to correctly predict the intrinsic response relative to a

  4. Fast, high-resolution 3D dosimetry utilizing a novel optical-CT scanner incorporating tertiary telecentric collimation.

    Science.gov (United States)

    Sakhalkar, H S; Oldham, M

    2008-01-01

    This study introduces a charge coupled device (CCD) area detector based optical-computed tomography (optical-CT) scanner for comprehensive verification of radiation dose distributions recorded in nonscattering radiochromic dosimeters. Defining characteristics include: (i) a very fast scanning time of approximately 5 min to acquire a complete three-dimensional (3D) dataset, (ii) improved image formation through the use of custom telecentric optics, which ensures accurate projection images and minimizes artifacts from scattered and stray-light sources, and (iii) high resolution (potentially 50 microm) isotropic 3D dose readout. The performance of the CCD scanner for 3D dose readout was evaluated by comparison with independent 3D readout from the single laser beam OCTOPUS-scanner for the same PRESAGE dosimeters. The OCTOPUS scanner was considered the "gold standard" technique in light of prior studies demonstrating its accuracy. Additional comparisons were made against calculated dose distributions from the ECLIPSE treatment-planning system. Dose readout for the following treatments were investigated: (i) a single rectangular beam irradiation to investigate small field and very steep dose gradient dosimetry away from edge effects, (ii) a 2-field open beam parallel-opposed irradiation to investigate dosimetry along steep dose gradients, and (iii) a 7-field intensity modulated radiation therapy (IMRT) irradiation to investigate dosimetry for complex treatment delivery involving modulation of fluence and for dosimetry along moderate dose gradients. Dose profiles, dose-difference plots, and gamma maps were employed to evaluate quantitative estimates of agreement between independently measured and calculated dose distributions. Results indicated that dose readout from the CCD scanner was in agreement with independent gold-standard readout from the OCTOPUS-scanner as well as the calculated ECLIPSE dose distribution for all treatments, except in regions within a few

  5. Evaluation of detectors for the small field measurements used for clinical radiation dosimetry

    Science.gov (United States)

    Markovic, Miljenko

    Advanced radiation therapy treatments with very small field sizes are complex. Increasingly higher doses delivered in single or few fractions are being commonly used for the treatments of the small target volume. Absolute or relative small field dosimetry is difficult due to radiation transport. Therefore it is very important to understand characteristics of the small field, detector selection as well as correction factors that have to be taken into account for the accurate measurements. Reducing uncertainty in relative dose measurement and modeling dose on treatment planning systems are factors contributing to the accuracy of the small field radiation treatments. Several challenges in small field dosimetry arise because of the lack of lateral charge particle equilibrium as well as the occlusion of the direct photon beam source and collimator settings. Presence of low-density media in irradiation geometry does complicate dosimetry even more. All those conditions are representing the challenge when it comes to dosimetric measurements. Size and construction are crucial when it comes to choice of the detector. Depending on beam energy, resolving the beam profile and penumbra for the small field sizes are a challenge and practically impossible with detectors commonly used in clinics. With decreasing field size and due to changes in particle spectrum, variations in radiological parameters have to be taken into account. To measure percent depth dose, tissue maximum ratios, tissue phantom ratios as well as output factors for the small field size experimental studies and Monte Carlo simulations have been conducted to determine appropriate detectors for the measurements. The primary goal of Specific Aim 1 was experimental quantification of the performance parameters for single detectors used for dosimetric verification of the small fields in radiotherapy. The proposed method and qualitative value for appropriate detectors selection defined by field size has been set. The

  6. Monte Carlo-based diode design for correction-less small field dosimetry

    Science.gov (United States)

    Charles, P. H.; Crowe, S. B.; Kairn, T.; Knight, R. T.; Hill, B.; Kenny, J.; Langton, C. M.; Trapp, J. V.

    2013-07-01

    Due to their small collecting volume, diodes are commonly used in small field dosimetry. However, the relative sensitivity of a diode increases with decreasing small field size. Conversely, small air gaps have been shown to cause a significant decrease in the sensitivity of a detector as the field size is decreased. Therefore, this study uses Monte Carlo simulations to look at introducing air upstream to diodes such that they measure with a constant sensitivity across all field sizes in small field dosimetry. Varying thicknesses of air were introduced onto the upstream end of two commercial diodes (PTW 60016 photon diode and PTW 60017 electron diode), as well as a theoretical unenclosed silicon chip using field sizes as small as 5 mm × 5 mm. The metric \\frac{{D_{w,Q} }}{{D_{Det,Q} }} used in this study represents the ratio of the dose to a point of water to the dose to the diode active volume, for a particular field size and location. The optimal thickness of air required to provide a constant sensitivity across all small field sizes was found by plotting \\frac{{D_{w,Q} }}{{D_{Det,Q} }} as a function of introduced air gap size for various field sizes, and finding the intersection point of these plots. That is, the point at which \\frac{{D_{w,Q} }}{{D_{Det,Q} }} was constant for all field sizes was found. The optimal thickness of air was calculated to be 3.3, 1.15 and 0.10 mm for the photon diode, electron diode and unenclosed silicon chip, respectively. The variation in these results was due to the different design of each detector. When calculated with the new diode design incorporating the upstream air gap, k_{Q_{clin} ,Q_{msr} }^{f_{clin} ,f_{msr} } was equal to unity to within statistical uncertainty (0.5%) for all three diodes. Cross-axis profile measurements were also improved with the new detector design. The upstream air gap could be implanted on the commercial diodes via a cap consisting of the air cavity surrounded by water equivalent material. The

  7. Designing and Dosimetry of a Shield for Photon Fields of Radiation Therapy in Oral Cavity Cancer

    OpenAIRE

    Jabbari, Keyvan; Senobari, Somayeh; Roayaei, Mahnaz; Rostampour, Masoumeh

    2015-01-01

    The cancer of oral cavity is related to lesions of mucous membrane of tongue and gum that can be treated with radiation therapy. A lateral photon field can be used to treat this kind of tumor, which has a side-effect on normal tissue in the opposite side of the oral cavity. In this study the dosimetric effect of the various shields in oral cavity is evaluated. In this study, a special phantom similar to the structure of oral cavity with capability of film dosimetry was designed and constructe...

  8. Dosimetry; La dosimetrie

    Energy Technology Data Exchange (ETDEWEB)

    Le Couteulx, I.; Apretna, D.; Beaugerie, M.F. [Electricite de France (EDF), 75 - Paris (France)] [and others

    2003-07-01

    Eight articles treat the dosimetry. Two articles evaluate the radiation doses in specific cases, dosimetry of patients in radiodiagnosis, three articles are devoted to detectors (neutrons and x and gamma radiations) and a computer code to build up the dosimetry of an accident due to an external exposure. (N.C.)

  9. Towards reference dosimetry for the MR-linac: magnetic field correction of the ionization chamber reading.

    Science.gov (United States)

    Smit, K; van Asselen, B; Kok, J G M; Aalbers, A H L; Lagendijk, J J W; Raaymakers, B W

    2013-09-07

    In the UMC Utrecht a prototype MR-linac has been installed. The system consists of a 6 MV Elekta (Crawley, UK) linear accelerator and a 1.5 T Philips (Best, The Netherlands) Achieva MRI system. This paper investigates the feasibility to correct the ionization chamber reading for the magnetic field within the dosimetry calibration method described by Almond et al (1999 Med. Phys. 26 1847-70). Firstly, the feasibility of using an ionization chamber in an MR-linac was assessed by investigating possible influences of the magnetic field on NE2571 Farmer-type ionization chamber characteristics: linearity, repeatability, orientation in the magnetic field; and AAPM TG51 correction factor for voltage polarity and ion recombination. We found that these AAPM correction factors for the NE2571 chamber were not influenced by the magnetic field. Secondly, the influence of the permanent 1.5 T magnetic field on the NE2571 chamber reading was quantified. The reading is influenced by the magnetic field; therefore, a correction factor has been added. For the standardized setup used in this paper, the NE2571 chamber reading increases by 4.9% (± 0.2%) due to the transverse 1.5 T magnetic field. Dosimetry measurements in an MR-linac are feasible, if a setup-specific magnetic field correction factor (P1.5 T) for the charge reading is introduced. For the setup investigated in this paper, the P1.5 T has a value of 0.953.

  10. SU-D-304-03: Small Field Proton Dosimetry Using MicroDiamond and Gafchromic Film

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, A; Das, I [Indiana University School of Medicine, Indianapolis, IN (United States); Coutinho, L [Procure Proton Therapy Center, Somerset, NJ, Pittstown, NJ (United States)

    2015-06-15

    Purpose: Certain dosimetric characteristics continue to make proton beam therapy an appealing modality for cancer treatment. The proton Bragg peak allows for conformal radiation dose delivery to the target while reducing dose to normal tissue and organs. As field sizes become very small the benefit of the Bragg peak is diminished due to loss of transverse equilibrium along the central beam axis. Furthermore, aperture scattering contributes additional dose along the central axis. These factors warrant the need for accurate small field dosimetry. In this study small field dosimetry was performed using two different methods. Methods: Small field dosimetry measurements were performed using a PTW microdiamond detector and Gafchromic EBT2 film for aperture sizes ranging from 0.5cm to 10cm and a proton range in water of 10cm to 27cm. The measurements were analyzed and then compared to each other and to reference dosimetry data acquired with a Markus chamber. Results: A decrease in normalized output is observed at small field sizes and at larger ranges in water using both measurement methods. Also, a large variation is observed between the output measurements by microdiamond and film at very small field sizes. At the smallest aperture, normalized output ranged from 0.16 to 0.72 and the percent difference between both measurement methods ranged from 36% to 70% depending on proton range. At field sizes above 5cm the film and microdiamond agree within 3%. Conclusion: Although both measurement methods exhibit a general decrease in output factor at small field sizes, dosimetric measurements for small fields using these two methods can vary significantly. Dosimetry under standard conditions is not sufficient to correctly model the dose distributions and outputs factors for small field sizes, additional small field measurements should be performed.

  11. Setup and dosimetry for exposing anaesthetised pigs in vivo to 900 MHz GSM mobile phone fields.

    Science.gov (United States)

    Toivonen, Tommi; Toivo, Tim; Pitkäaho, Risto; Puranen, Lauri; Silfverhuth, Minna; Mennander, Ari; Hannula, Markus; Hyttinen, Jari; Jokela, Kari

    2008-07-01

    The aim of this study was a dosimetrical analysis of the setup used in the exposure of the heads of domestic pigs to GSM-modulated radio frequency electromagnetic fields (RF-EMF) at 900 MHz. The heads of pigs were irradiated with a half wave dipole using three different exposure routines; short bursts of 1-3 s at two different exposure levels and a continuous 10-min exposure. The electroencephalogram (EEG) was registered continuously during the exposures to search for RF-EMF originated changes. The dosimetry was based on simulations with the anatomical heterogeneous numerical model of the pig head. The simulation results were validated by experimental measurements with the exposure dipole and a homogeneous liquid phantom resembling the pig head. The specific absorption rate (SAR), defined as a maximum average over 10 g tissue mass (SAR(10g)), was 7.3 W/kg for the first set of short bursts and 31 W/kg for the second set of short bursts. The SAR(10g) in the continuous 10-min exposure was 31 W/kg. The estimated uncertainty for the dosimetry was +/-25% (K = 2).

  12. Dosimetry of cone-defined stereotactic radiosurgery fields with a commercial synthetic diamond detector

    Energy Technology Data Exchange (ETDEWEB)

    Morales, Johnny E., E-mail: johnny.morales@lh.org.au [Department of Radiation Oncology, Chris O’Brien Lifehouse, 119-143 Missenden Road, Camperdown, NSW 2050, Australia and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Level 4 O Block, Garden’s Point, Brisbane, QLD 4001 (Australia); Crowe, Scott B.; Trapp, J. V. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Level 4 O Block, Garden’s Point, Brisbane, QLD 4001 (Australia); Hill, Robin [Department of Radiation Oncology, Chris O’Brien Lifehouse, 119-143 Missenden Road, Camperdown, NSW 2050 (Australia); Freeman, Nigel [Department of Radiation Oncology, St Vincent’s Hospital, Victoria Street, Darlinghurst, NSW 2010 (Australia)

    2014-11-01

    Purpose: Small field x-ray beam dosimetry is difficult due to lack of lateral electronic equilibrium, source occlusion, high dose gradients, and detector volume averaging. Currently, there is no single definitive detector recommended for small field dosimetry. The objective of this work was to evaluate the performance of a new commercial synthetic diamond detector, namely, the PTW 60019 microDiamond, for the dosimetry of small x-ray fields as used in stereotactic radiosurgery (SRS). Methods: Small field sizes were defined by BrainLAB circular cones (4–30 mm diameter) on a Novalis Trilogy linear accelerator and using the 6 MV SRS x-ray beam mode for all measurements. Percentage depth doses (PDDs) were measured and compared to an IBA SFD and a PTW 60012 E diode. Cross profiles were measured and compared to an IBA SFD diode. Field factors, Ω{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}}, were calculated by Monte Carlo methods using BEAMnrc and correction factors, k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}}, were derived for the PTW 60019 microDiamond detector. Results: For the small fields of 4–30 mm diameter, there were dose differences in the PDDs of up to 1.5% when compared to an IBA SFD and PTW 60012 E diode detector. For the cross profile measurements the penumbra values varied, depending upon the orientation of the detector. The field factors, Ω{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}}, were calculated for these field diameters at a depth of 1.4 cm in water and they were within 2.7% of published values for a similar linear accelerator. The corrections factors, k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}}, were derived for the PTW 60019 microDiamond detector. Conclusions

  13. Correction factors for ionization chamber dosimetry in CyberKnife: Machine-specific, plan-class, and clinical fields

    Energy Technology Data Exchange (ETDEWEB)

    Gago-Arias, Araceli; Antolin, Elena; Fayos-Ferrer, Francisco; Simon, Rocio; Gonzalez-Castano, Diego M.; Palmans, Hugo; Sharpe, Peter; Gomez, Faustino; Pardo-Montero, Juan [Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782 (Spain); Servicio de Fisica Medica, Hospital Ruber Internacional, Madrid 28034 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782, Spain and Laboratorio de Radiofisica, Universidade de Santiago de Compostela, Santiago de Compostela, A Coruna 15782 (Spain); National Physical Laboratory, Teddington, Middx TW11 OLW (United Kingdom); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782, Spain and Laboratorio de Radiofisica, Universidade de Santiago de Compostela, Santiago de Compostela, A Coruna 15782 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidade de Santiago de Compostela, A Coruna 15782 (Spain)

    2013-01-15

    Purpose: The aim of this work is the application of the formalism for ionization chamber reference dosimetry of small and nonstandard fields [R. Alfonso, P. Andreo, R. Capote, M. S. Huq, W. Kilby, P. Kjaell, T. R. Mackie, H. Palmans, K. Rosser, J. Seuntjens, W. Ullrich, and S. Vatnitsky, 'A new formalism for reference dosimetry of small and nonstandard fields,' Med. Phys. 35, 5179-5186 (2008)] to the CyberKnife robotic radiosurgery system. Correction factors for intermediate calibration fields, a machine-specific reference field (msr) and two plan-class specific reference fields (pcsr), have been studied. Furthermore, the applicability of the new formalism to clinical dosimetry has been analyzed through the investigation of two clinical treatments. Methods: PTW31014 and Scanditronix-Wellhofer CC13 ionization chamber measurements were performed for the fields under investigation. Absorbed dose to water was determined using alanine reference dosimetry, and experimental correction factors were calculated from alanine to ionization chamber readings ratios. In addition, correction factors were calculated for the intermediate calibration fields and one of the clinical treatment fields using the Monte Carlo method and these were compared with the experimental values. Results: Overall correction factors deviating from unity by approximately 2% were obtained from both measurements and simulations, with values below and above unity for the studied intermediate calibration fields and clinical fields for the ionization chambers under consideration. Monte Carlo simulations yielded correction factors comparable with those obtained from measurements for the machine-specific reference field, although differences from 1% to 3.3% were observed between measured and calculated correction factors for the composite intermediate calibration fields. Dose distribution inhomogeneities are thought to be responsible for such discrepancies. Conclusions: The differences found between

  14. Evaluation of the uncertainty in an EBT3 film dosimetry system utilizing net optical density.

    Science.gov (United States)

    León Marroquin, Elsa Y; Herrera González, José A; Camacho López, Miguel A; Villarreal Barajas, José E; García-Garduño, Olivia A

    2016-01-01

    Radiochromic film has become an important tool to verify dose distributions for intensity-modulated radiotherapy (IMRT) and quality assurance (QA) procedures. A new radiochromic film model, EBT3, has recently become available, whose composition and thickness of the sensitive layer are the same as those of previous EBT2 films. However, a matte polyester layer was added to EBT3 to prevent the formation of Newton's rings. Furthermore, the symmetrical design of EBT3 allows the user to eliminate side-orientation dependence. This film and the flatbed scanner, Epson Perfection V750, form a dosimetry system whose intrinsic characteristics were studied in this work. In addition, uncertainties associated with these intrinsic characteristics and the total uncertainty of the dosimetry system were determined. The analysis of the response of the radiochromic film (net optical density) and the fitting of the experimental data to a potential function yielded an uncertainty of 2.6%, 4.3%, and 4.1% for the red, green, and blue channels, respectively. In this work, the dosimetry system presents an uncertainty in resolving the dose of 1.8% for doses greater than 0.8 Gy and less than 6 Gy for red channel. The films irradiated between 0 and 120 Gy show differences in the response when scanned in portrait or landscape mode; less uncertainty was found when using the portrait mode. The response of the film depended on the position on the bed of the scanner, contributing an uncertainty of 2% for the red, 3% for the green, and 4.5% for the blue when placing the film around the center of the bed of scanner. Furthermore, the uniformity and reproducibility radiochromic film and reproducibility of the response of the scanner contribute less than 1% to the overall uncertainty in dose. Finally, the total dose uncertainty was 3.2%, 4.9%, and 5.2% for red, green, and blue channels, respectively. The above uncertainty values were obtained by mini-mizing the contribution to the total dose uncertainty

  15. Mixed field dosimetry using focused and unfocused laser heating of thermoluminescent materials

    Energy Technology Data Exchange (ETDEWEB)

    Han, S.

    1994-03-01

    The incidents at the Three Mile Island and Chernobyl have triggered the need for better personnel dosimetry methods in mixed radiation fields. This thesis presents a detailed computational study of a new method for mixed radiation field dosimetry using single-element TL dosimeters with pulsed laser heating schemes. The main objective of this study was to obtain an optimum heating scheme so that the depth-dose distribution in a thick TL dosimeter could be accurately determined. The major parts of the study include: (a) heat conduction calculations for TL dosimeters with various heating schemes, (b) glow curve calculations for TL dosimeters based on a first-order kinetic model, (c) unfolding of the depth-dose distribution based on the glow curve data, and (d) estimation of shallow and deep doses from the unfolded depth-dose distribution. Two optimum heating schemes were obtained in this study. The first one was obtained for a focused laser beam, and the second one was obtained for a uniform laser beam. Both heating schemes consist of two processes: top surface heating and bottom surface heating, and each process in turn consists of a sequence of laser pulses with various heating durations and power levels. Compared to the ``true`` depth-dose distribution obtained using Monte Carlo transport code EGS4, relative errors associated with the shallow and deep doses obtained from the unfolded depth-dose distributions are 5% and 25%, respectively, for the focused laser beam, and 15% in both doses for the uniform laser beam. 74 refs., 148 figs.

  16. (Biological dosimetry)

    Energy Technology Data Exchange (ETDEWEB)

    Preston, R.J.

    1990-12-17

    The traveler attended the 1st International Conference on Biological Dosimetry in Madrid, Spain. This conference was organized to provide information to a general audience of biologists, physicists, radiotherapists, industrial hygiene personnel and individuals from related fields on the current ability of cytogenetic analysis to provide estimates of radiation dose in cases of occupational or environmental exposure. There is a growing interest in Spain in biological dosimetry because of the increased use of radiation sources for medical and occupational uses, and with this the anticipated and actual increase in numbers of overexposure. The traveler delivered the introductory lecture on Biological Dosimetry: Mechanistic Concepts'' that was intended to provide a framework by which the more applied lectures could be interpreted in a mechanistic way. A second component of the trip was to provide advice with regard to several recent cases of overexposure that had been or were being assessed by the Radiopathology and Radiotherapy Department of the Hospital General Gregorio Maranon'' in Madrid. The traveler had provided information on several of these, and had analyzed cells from some exposed or purportedly exposed individuals. The members of the biological dosimetry group were referred to individuals at REACTS at Oak Ridge Associated Universities for advice on follow-up treatment.

  17. Designing and Dosimetry of a Shield for Photon Fields of Radiation Therapy in Oral Cavity Cancer

    Science.gov (United States)

    Jabbari, Keyvan; Senobari, Somayeh; Roayaei, Mahnaz; Rostampour, Masoumeh

    2015-01-01

    The cancer of oral cavity is related to lesions of mucous membrane of tongue and gum that can be treated with radiation therapy. A lateral photon field can be used to treat this kind of tumor, which has a side-effect on normal tissue in the opposite side of the oral cavity. In this study the dosimetric effect of the various shields in oral cavity is evaluated. In this study, a special phantom similar to the structure of oral cavity with capability of film dosimetry was designed and constructed. The various shield slabs were made of five materials: Lead, Plexiglas, Acrylic resin, Silicon and Plaster. For irradiation, Cobalt 60 (60Co) and 6 MV photon beams were used. The film dosimetry before and after the shield was performed using GAFCHROMIC EBT2 films. The film before the shield measures the magnitude of backscattering radiation from the shield. The prescribed dose was 150 cGy. Results showed that 3 cm of the lead in both energies had the maximum absorption of radiation. The absorbed dose to opposite side of shield for 6 MV photon beams and 60Co were 21 and 32 cGy, respectively. The minimum attenuation on radiation was observed in silicon shield for which the dose of opposite side were 116 and 147 cGy for 6 MV and 60Co respectively. The maximum backscattered dose was measured 177 cGy and 219 cGy using 3 cm thickness of lead, which was quite considerable. The minimum backscattering where for acrylic resin 101 and 118 cGy for 6 MV and cobalt. In this study, it was concluded that the amount of backscattering for 3 cm Lead shield is quite considerable and increases the dose significantly. A composite layer of shield with 1–2 cm lead and 1 cm acrylic resin can have the protective effect and low backscattering radiation at the same time. PMID:26120570

  18. ESR-dosimetry in thermal and epithermal neutron fields for application in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Tobias

    2016-01-22

    Dosimetry is essential for every form of radiotherapy. In Boron Neutron Capture Therapy (BNCT) mixed neutron and gamma fields have to be considered. Dose is deposited in different neutron interactions with elements in the penetrated tissue and by gamma particles, which are always part of a neutron field. The therapeutic dose in BNCT is deposited by densely ionising particles, originating from the fragmentation of the isotope boron-10 after capture of a thermal neutron. Despite being investigated for decades, dosimetry in neutron beams or fields for BNCT remains complex, due to the variety in type and energy of the secondary particles. Today usually ionisation chambers combined with metal foils are used. The applied techniques require extensive effort and are time consuming, while the resulting uncertainties remain high. Consequently, the investigation of more effective techniques or alternative dosimeters is an important field of research. In this work the possibilities of ESR-dosimeters in those fields have been investigated. Certain materials, such as alanine, generate stable radicals upon irradiation. Using Electron Spin Resonance (ESR) spectrometry the amount of radicals, which is proportional to absorbed dose, can be quantified. Different ESR detector materials have been irradiated in the thermal neutron field of the research reactor TRIGA research reactor in Mainz, Germany, with five setups, generating different secondary particle spectra. Further irradiations have been conducted in two epithermal neutron beams. The detector response, however, strongly depends on the dose depositing particle type and energy. It is hence necessary to accompany measurements by computational modelling and simulation. In this work the Monte Carlo code FLUKA was used to calculate absorbed doses and dose components. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using amorphous track models. For the simulation, detailed models of

  19. MAGAT gel dosimetry for its application in small field treatment techniques

    Science.gov (United States)

    Gopishankar, N.; Vivekanandhan, S.; Kale, S. S.; Rath, G. K.; Senthil Kumaran, S.; Thulkar, Sanjay; Subramani, V.; Laviraj, M. A.; Bisht, R. K.; Mahapatra, A. K.

    2010-11-01

    Purpose of this work is to present the role of in-house manufactured MAGAT gel for treatment verification in small field dosimetric techniques such as Gammaknife (GK) and intensity-modulated radiation therapy (IMRT). Magnetic resonance imaging (MRI) is one of the most extensively used imaging technique for polymer gel dosimetry hence we used this method for gel evaluation. Different MR scanners and MRI sequences were used in this study for obtaining calibration plot between R2 and absorbed dose. An experimental plan was created for Gammaknife and IMRT. The prepared gel was filled in spherical glass phantom and in-house designed human head shape phantom for verification purpose. We used 8 TE values for all the imaging sequences for two reasons. Firstly it is sufficient enough to give good signal to noise ratio. Second considering the enormous scanning time involved in multiple spin echo sequence. MATLAB based in-house programs were used for R2 estimation and dose comparison. The isodose comparison with MAGAT gel showed reasonable agreement for both Gammaknife and IMRT techniques.

  20. Use of novel fibre-coupled radioluminescence and RADPOS dosimetry systems for total scatter factor measurements in small fields

    Science.gov (United States)

    Ploquin, N.; Kertzscher, G.; Vandervoort, E.; Cygler, J. E.; Andersen, C. E.; Francescon, P.

    2015-01-01

    A dosimetry system based on Al2O3:C radioluminescence (RL), and RADPOS, a novel 4D dosimetry system using microMOSFETs, were used to measure total scatter factors, ≤ft({{S}c,p}\\right)\\text{det}{{f\\text{clin}}}, for the CyberKnife robotic radiosugery system. New Monte Carlo calculated correction factors are presented and applied for the RL detector response for the 5, 7.5 and 10 mm collimators in order to correct for the detector geometry and increased photoelectric cross section of Al2O3:C relative to water. For comparison, measurements were also carried out using a micro MOSFET, PTW60012 diode and GAFCHROMIC® film (EBT and EBT2). Uncorrected ≤ft({{S}c,p}\\right)\\text{det}{{f\\text{clin}}}, were obtained by taking the ratio of the detector response for each collimator to that for the 60 mm diameter reference field. Published Monte Carlo calculated correction factors were applied to the RADPOS, microMOSFET and diode detector measurements to yield corrected field factors, Ω {{Q\\text{clin}},{{Q}\\text{msr}}}{{f\\text{clin}},{{f}\\text{msr}}}, following the terminology of a recent formalism introduced for small and composite field relative dosimetry. With corrections, the RL measured Ω {{Q\\text{clin}},{{Q}\\text{msr}}}{{f\\text{clin}},{{f}\\text{msr}}}, were 0.656  ±  0.002, 0.815  ±  0.002 and 0.865  ±  0.003 for the 5, 7.5 and 10 mm collimators, respectively. This was in good agreement with RADPOS corrected field factors of 0.650  ±  0.010, 0.816  ±  0.024 and 0.867  ±  0.010 for the 5, 7.5 and 10 mm collimators, respectively. Both RL and RADPOS total scatter factors agreed within approximately two standard deviations of the GAFCHROMIC film values (average of EBT and EBT2) of 0.640  ±  0.006, 0.806  ±  0.007 and 0.859  ±  0.09. Corrected total scatter factors for all dosimetry systems agreed within one standard deviation for collimator sizes 10-60 mm. Our study suggests that the micro

  1. Use of novel fibre-coupled radioluminescence and RADPOS dosimetry systems for total scatter factor measurements in small fields.

    Science.gov (United States)

    Ploquin, N; Kertzscher, G; Vandervoort, E; Cygler, J E; Andersen, C E; Francescon, P

    2015-01-07

    A dosimetry system based on Al2O3:C radioluminescence (RL), and RADPOS, a novel 4D dosimetry system using microMOSFETs, were used to measure total scatter factors, (S(c,p))(f(clin))(det), for the CyberKnife robotic radiosugery system. New Monte Carlo calculated correction factors are presented and applied for the RL detector response for the 5, 7.5 and 10 mm collimators in order to correct for the detector geometry and increased photoelectric cross section of Al2O3:C relative to water. For comparison, measurements were also carried out using a micro MOSFET, PTW60012 diode and GAFCHROMIC(®) film (EBT and EBT2). Uncorrected (S(c,p))(f(clin))(det) were obtained by taking the ratio of the detector response for each collimator to that for the 60 mm diameter reference field. Published Monte Carlo calculated correction factors were applied to the RADPOS, microMOSFET and diode detector measurements to yield corrected field factors, Ω(f(clin),f(msr))(Q(clin),Q(msr)), following the terminology of a recent formalism introduced for small and composite field relative dosimetry. With corrections, the RL measured Ω(f(clin),f(msr))(Q(clin),Q(msr)) were 0.656  ±  0.002, 0.815  ±  0.002 and 0.865  ±  0.003 for the 5, 7.5 and 10 mm collimators, respectively. This was in good agreement with RADPOS corrected field factors of 0.650  ±  0.010, 0.816  ±  0.024 and 0.867  ±  0.010 for the 5, 7.5 and 10 mm collimators, respectively. Both RL and RADPOS total scatter factors agreed within approximately two standard deviations of the GAFCHROMIC film values (average of EBT and EBT2) of 0.640  ±  0.006, 0.806  ±  0.007 and 0.859  ±  0.09. Corrected total scatter factors for all dosimetry systems agreed within one standard deviation for collimator sizes 10-60 mm. Our study suggests that the microMOSFET/RADPOS and optical fibre-coupled RL dosimetry system are well suited for total scatter factor measurements over the entire range of field

  2. Evaluation of individual dosimetry in mixed neutron and photon radiation fields (EVIDOS). Part I: Scope and methods of the project.

    Science.gov (United States)

    d'Errico, F; Bartlett, D; Bolognese-Milsztajn, T; Boschung, M; Coeck, M; Curzio, G; Fiechtner, A; Kyllönen, J-E; Lacoste, V; Lindborg, L; Luszik-Bhadra, M; Reginatto, M; Schuhmacher, H; Tanner, R; Vanhavere, F

    2007-01-01

    Supported by the European Commission, the EVIDOS project started in November 2001 with the broad goal of evaluating state of the art dosimetry techniques in representative workplaces of the nuclear industry. Seven European institutes joined efforts with end users at nuclear power plants, at fuel processing and reprocessing plants, and at transport and storage facilities. A comprehensive programme was devised to evaluate capabilities and limitations of standard and innovative personal dosemeters in relation to the mixed neutron-photon fields of concern to the nuclear industry. This paper describes the criteria behind the selection of dosimetry techniques and workplaces that were analysed, as well as the organisation of the measurement campaigns. Particular emphasis was placed on the evaluation of a variety of electronic personal dosemeters, either commercially available or previously developed by the partners. The estimates provided by these personal dosemeters were compared to reference values of dose equivalent quantities derived from spectrometry and fluence-to-dose equivalent conversion coefficients. Spectrometry was performed both with conventional multisphere and with some original instrumentation providing energy and direction resolution, based on silicon detectors and superheated drop detectors mounted on or in spherical moderators. The results were collected in a large, searchable database and are intended to be used in the harmonisation of dosimetric procedures for mixed radiation fields and for the approval of dosimetry services in Europe.

  3. K-band EPR dosimetry: small-field beam profile determination with miniature alanine dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Felipe [Departmento de Fisica e Matematica, FFCLRP-Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto-SP (Brazil); Department of Radiological Health, Caja de Seguro Social, Panama City (Panama); Department of Physics, Faculty of Natural and Exact Sciences and Technology, University of Panama, Panama City (Panama); Graeff, Carlos F.O. [Departmento de Fisica e Matematica, FFCLRP-Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto-SP (Brazil); Baffa, Oswaldo [Departmento de Fisica e Matematica, FFCLRP-Universidade de Sao Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirao Preto-SP (Brazil)

    2005-02-01

    The use of small-size alanine dosimeters presents a challenge because the signal intensity is less than the spectrometer sensitivity. K-band (24 GHz) EPR spectrometer seems to be a good compromise between size and sensitivity of the sample. Miniature alanine pellets were evaluated for small-field radiation dosimetry. Dosimeters of DL-alanine/PVC with dimensions of 1.5 mm diameter and 2.5 mm length with 5 mg mass were developed. These dosimeters were irradiated with 10 MV X-rays in the dose range 0.05-60 Gy and the first harmonic (1 h) spectra were recorded. Microwave power, frequency and amplitude of modulation were optimized to obtain the best signal-to-noise ratio (S/N). For beam profile determination, a group of 25 dosimeters were placed in an acrylic device with dimensions of (7.5x2.5x1) cm{sup 3} and irradiated with a (3x3) cm{sup 2} 10 MV X-rays beam field size. The dose at the central region of the beam was 20 Gy at a depth of 2.2 cm (build up for acrylic). The acrylic device was oriented perpendicular to the beam axis and to the gantry rotation axis. For the purposes of comparison of the spatial resolution, the beam profile was also determined with a radiographic film and 2 mm aperture optical densitometer; in this case the dose was 1 cGy. The results showed a similar spatial resolution for both types of dosimeters. The dispersion in dose reading was larger for alanine in comparison with the film, but alanine dosimeters can be read faster and more directly than film over a wide dose range.

  4. Status of radiation processing dosimetry

    DEFF Research Database (Denmark)

    Miller, A.

    1993-01-01

    Several milestones have marked the field of radiation processing dosimetry since IMRP 7. Among them are the IAEA symposium on High Dose Dosimetry for Radiation Processing and the international Workshops on Dosimetry for Radiation Processing organized by the ASTM. Several standards have been...... or are being published by the ASTM in this field, both on dosimetry procedures and on the proper use of specific dosimeter systems. Several individuals are involved in this international cooperation which contribute significantly to the broader understanding of the role of dosimetry in radiation processing....... The importance of dosimetry is emphasized in the standards on radiation sterilization which are currently drafted by the European standards organization CEN and by the international standards organization ISO. In both standards, dosimetry plays key roles in characterization of the facility, in qualification...

  5. The history and principles of chemical dosimetry for 3-D radiation fields: gels, polymers and plastics.

    Science.gov (United States)

    Doran, Simon J

    2009-03-01

    Over recent decades, modern protocols of external beam radiotherapy have been developed that involve very steep dose gradients and are thus extremely sensitive to errors in treatment delivery. A recent credentialling study by the Radiological Physics Center at the MD Anderson Cancer Center (Texas, USA) has noted potentially significant inaccuracies in test treatments at a variety of institutions. 3-D radiation dosimetry (often referred to as "gel dosimetry") may have an important role in commissioning new treatment protocols, to help prevent this type of error. This article discusses the various techniques of 3-D radiation dosimetry, with a focus on the types of radiosensitive samples used and on the optical computed tomography readout technique.

  6. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    Directory of Open Access Journals (Sweden)

    Timothy Olding

    2011-01-01

    Full Text Available This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI. For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low′s gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery. When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low′s gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a from the same gel batch and (b from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.

  7. Radiation dosimetry

    CERN Document Server

    Hine, Gerald J; Hine, Gerald J

    1956-01-01

    Radiation Dosimetry focuses on the advancements, processes, technologies, techniques, and principles involved in radiation dosimetry, including counters and calibration and standardization techniques. The selection first offers information on radiation units and the theory of ionization dosimetry and interaction of radiation with matter. Topics include quantities derivable from roentgens, determination of dose in roentgens, ionization dosimetry of high-energy photons and corpuscular radiations, and heavy charged particles. The text then examines the biological and medical effects of radiation,

  8. Utilizing a simple CT dosimetry phantom for the comprehension of the operational characteristics of CT AEC systems

    Energy Technology Data Exchange (ETDEWEB)

    Tsalafoutas, Ioannis A. [Medical Physics Department, Anticancer-Oncology Hospital of Athens “Agios Savvas,” 171 Alexandras Avenue, 115 22 Athens (Greece); Varsamidis, Athanasios; Thalassinou, Stella; Efstathopoulos, Efstathios P. [Second Department of Radiology, Medical School, University of Athens, University General Hospital, “Attikon,” Rimini 1, 124 62 Athens (Greece)

    2013-11-15

    Purpose: To investigate the utility of the nested polymethylacrylate (PMMA) phantom (which is available in many CT facilities for CTDI measurements), as a tool for the presentation and comparison of the ways that two different CT automatic exposure control (AEC) systems respond to a phantom when various scan parameters and AEC protocols are modified.Methods: By offsetting the two phantom's components (the head phantom and the body ring) half-way along their longitudinal axis, a phantom with three sections of different x-ray attenuation was created. Scan projection radiographs (SPRs) and helical scans of the three-section phantom were performed on a Toshiba Aquilion 64 and a Philips Brilliance 64 CT scanners, with different scan parameter selections [scan direction, pitch factor, slice thickness, and reconstruction interval (ST/RI), AEC protocol, and tube potential used for the SPRs]. The dose length product (DLP) values of each scan were recorded and the tube current (mA) values of the reconstructed CT images were plotted against the respective Z-axis positions on the phantom. Furthermore, measurements of the noise levels at the center of each phantom section were performed to assess the impact of mA modulation on image quality.Results: The mA modulation patterns of the two CT scanners were very dissimilar. The mA variations were more pronounced for Aquilion 64, where changes in any of the aforementioned scan parameters affected both the mA modulations curves and DLP values. However, the noise levels were affected only by changes in pitch, ST/RI, and AEC protocol selections. For Brilliance 64, changes in pitch affected the mA modulation curves but not the DLP values, whereas only AEC protocol and SPR tube potential selection variations affected both the mA modulation curves and DLP values. The noise levels increased for smaller ST/RI, larger weight category AEC protocol, and larger SPR tube potential selection.Conclusions: The nested PMMA dosimetry phantom can

  9. SU-C-201-06: Utility of Quantitative 3D SPECT/CT Imaging in Patient Specific Internal Dosimetry of 153-Samarium with GATE Monte Carlo Package

    Energy Technology Data Exchange (ETDEWEB)

    Fallahpoor, M; Abbasi, M [Tehran University of Medical Sciences, Vali-Asr Hospital, Tehran, Tehran (Iran, Islamic Republic of); Sen, A [University of Houston, Houston, TX (United States); Parach, A [Shahid Sadoughi University of Medical Sciences, Yazd, Yazd (Iran, Islamic Republic of); Kalantari, F [UT Southwestern Medical Center, Dallas, TX (United States)

    2015-06-15

    Purpose: Patient-specific 3-dimensional (3D) internal dosimetry in targeted radionuclide therapy is essential for efficient treatment. Two major steps to achieve reliable results are: 1) generating quantitative 3D images of radionuclide distribution and attenuation coefficients and 2) using a reliable method for dose calculation based on activity and attenuation map. In this research, internal dosimetry for 153-Samarium (153-Sm) was done by SPECT-CT images coupled GATE Monte Carlo package for internal dosimetry. Methods: A 50 years old woman with bone metastases from breast cancer was prescribed 153-Sm treatment (Gamma: 103keV and beta: 0.81MeV). A SPECT/CT scan was performed with the Siemens Simbia-T scanner. SPECT and CT images were registered using default registration software. SPECT quantification was achieved by compensating for all image degrading factors including body attenuation, Compton scattering and collimator-detector response (CDR). Triple energy window method was used to estimate and eliminate the scattered photons. Iterative ordered-subsets expectation maximization (OSEM) with correction for attenuation and distance-dependent CDR was used for image reconstruction. Bilinear energy mapping is used to convert Hounsfield units in CT image to attenuation map. Organ borders were defined by the itk-SNAP toolkit segmentation on CT image. GATE was then used for internal dose calculation. The Specific Absorbed Fractions (SAFs) and S-values were reported as MIRD schema. Results: The results showed that the largest SAFs and S-values are in osseous organs as expected. S-value for lung is the highest after spine that can be important in 153-Sm therapy. Conclusion: We presented the utility of SPECT-CT images and Monte Carlo for patient-specific dosimetry as a reliable and accurate method. It has several advantages over template-based methods or simplified dose estimation methods. With advent of high speed computers, Monte Carlo can be used for treatment planning

  10. Hematological dosimetry. Dosimetrie hematologique

    Energy Technology Data Exchange (ETDEWEB)

    Fluery-Herard, A. (CEA Centre d' Etudes de Fontenay-aux-Roses, 92 (FR). Direction des Sciences du Vivant)

    1991-01-01

    The principles of hematological dosimetry after acute or protracted whole-body irradiation are reviewed. In both cases, over-exposure is never homogeneous and the clinical consequences, viz medullary aplasia, are directly associated with the mean absorbed dose and the seriousness and location of the overexposure. The main hematological data required to assess the seriousness of exposure are the following: repeated blood analysis, blood precursor cultures, as indicators of whole-body exposure; bone marrow puncture, medullary precursor cultures and medullary scintigraphy as indicators of the importance of a local over-exposure and capacity for spontaneous repair. These paraclinical investigations, which are essential for diagnosis and dosimetry, are also used for surveillance and for the main therapeutic issues.

  11. Dosimetry Service

    CERN Multimedia

    2006-01-01

    Cern Staff and Users can now consult their dose records for an individual or an organizational unit with HRT. Please see more information on our web page: http://cern.ch/rp-dosimetry Dosimetry Service is open every morning from 8.30 - 12.00. Closed in the afternoons. We would like to remind you that dosimeters cannot be sent to customers by internal mail. Short-term dosimeters (VCT's) must always be returned to the Service after the use and must not be left on the racks in the experimental areas or in the secretariats. Dosimetry Service Tel. 7 2155 Dosimetry.service@cern.ch http://cern.ch/rp-dosimetry

  12. Upgrading the dosimetry at Ontario Hydro

    Energy Technology Data Exchange (ETDEWEB)

    Hirning, C.R. [Ontario Hydro, Whitby, ON (Canada). Health Physics Dept.

    1996-12-01

    Ontario Hydro has embarked upon a major programme to replace and upgrade its external dosimetry systems. In two year`s time, the utility expects to have two state-of-the-art dosimetry systems in place: a new TLD dosimetry of legal record that was designed nearly 30 years ago; and an electronic dosimetry system which could eventually replace the TLD as the primary system. (Author).

  13. Comparison of Flattening Filter (FF) and Flattening-Filter-Free (FFF) 6 MV photon beam characteristics for small field dosimetry using EGSnrc Monte Carlo code

    Science.gov (United States)

    Sangeetha, S.; Sureka, C. S.

    2017-06-01

    The present study is focused to compare the characteristics of Varian Clinac 600 C/D flattened and unflattened 6 MV photon beams for small field dosimetry using EGSnrc Monte Carlo Simulation since the small field dosimetry is considered to be the most crucial and provoking task in the field of radiation dosimetry. A 6 MV photon beam of a Varian Clinac 600 C/D medical linear accelerator operates with Flattening Filter (FF) and Flattening-Filter-Free (FFF) mode for small field dosimetry were performed using EGSnrc Monte Carlo user codes (BEAMnrc and DOSXYZnrc) in order to calculate the beam characteristics using Educated-trial and error method. These includes: Percentage depth dose, lateral beam profile, dose rate delivery, photon energy spectra, photon beam uniformity, out-of-field dose, surface dose, penumbral dose and output factor for small field dosimetry (0.5×0.5 cm2 to 4×4 cm2) and are compared with magna-field sizes (5×5 cm2 to 40×40 cm2) at various depths. The results obtained showed that the optimized beam energy and Full-width-half maximum value for small field dosimetry and magna-field dosimetry was found to be 5.7 MeV and 0.13 cm for both FF and FFF beams. The depth of dose maxima for small field size deviates minimally for both FF and FFF beams similar to magna-fields. The depths greater than dmax depicts a steeper dose fall off in the exponential region for FFF beams comparing FF beams where its deviations gets increased with the increase in field size. The shape of the lateral beam profiles of FF and FFF beams varies remains similar for the small field sizes less than 4×4 cm2 whereas it varies in the case of magna-fields. Dose rate delivery for FFF beams shows an eminent increase with a two-fold factor for both small field dosimetry and magna-field sizes. The surface dose measurements of FFF beams for small field size were found to be higher whereas it gets lower for magna-fields than FF beam. The amount of out-of-field dose reduction gets

  14. An integral field spectrograph utilizing mirrorlet arrays

    Science.gov (United States)

    Chamberlin, Phillip C.; Gong, Qian

    2016-09-01

    An integral field spectrograph (IFS) has been developed that utilizes a new and novel optical design to observe two spatial dimensions simultaneously with one spectral dimension. This design employs an optical 2-D array of reflecting and focusing mirrorlets. This mirrorlet array is placed at the imaging plane of the front-end telescope to generate a 2-D array of tiny spots replacing what would be the slit in a traditional slit spectrometer design. After the mirrorlet in the optical path, a grating on a concave mirror surface will image the spot array and provide high-resolution spectrum for each spatial element at the same time; therefore, the IFS simultaneously obtains the 3-D data cube of two spatial and one spectral dimensions. The new mirrorlet technology is currently in-house and undergoing laboratory testing at NASA Goddard Space Flight Center. Section 1 describes traditional classes of instruments that are used in Heliophysics missions and a quick introduction to the new IFS design. Section 2 discusses the details of the most generic mirrorlet IFS, while section 3 presents test results of a lab-based instrument. An example application to a Heliophysics mission to study solar eruptive events in extreme ultraviolet wavelengths is presented in section 4 that has high spatial resolution (0.5 arc sec pixels) in the two spatial dimensions and high spectral resolution (66 mÅ) across a 15 Å spectral window. Section 4 also concludes with some other optical variations that could be employed on the more basic IFS for further capabilities of this type of instrument.

  15. An Integral Field Spectrograph Utilizing Mirrorlet Arrays

    Science.gov (United States)

    Chamberlin, Phillip C.; Gong, Qian

    2016-01-01

    An integral field spectrograph (IFS) has been developed that utilizes a new and novel optical design to observe two spatial dimensions simultaneously with one spectral dimension. This design employs an optical 2-D array of reflecting and focusing mirrorlets. This mirrorlet array is placed at the imaging plane of the front-end telescope to generate a 2-D array of tiny spots replacing what would be the slit in a traditional slit spectrometer design. After the mirrorlet in the optical path, a grating on a concave mirror surface will image the spot array and provide high-resolution spectrum for each spatial element at the same time; therefore, the IFS simultaneously obtains the 3-D data cube of two spatial and one spectral dimensions. The new mirrorlet technology is currently in-house and undergoing laboratory testing at NASA Goddard Space Flight Center. Section 1 describes traditional classes of instruments that are used in Heliophysics missions and a quick introduction to the new IFS design. Section 2 discusses the details of the most generic mirrorlet IFS, while section 3 presents test results of a lab-based instrument. An example application to a Heliophysics mission to study solar eruptive events in extreme ultraviolet wavelengths is presented in section 4 that has high spatial resolution (0.5 arc sec pixels) in the two spatial dimensions and high spectral resolution (66 m) across a 15 spectral window. Section 4 also concludes with some other optical variations that could be employed on the more basic IFS for further capabilities of this type of instrument.

  16. Application of the planar-scanning technique to the near-field dosimetry of millimeter-wave radiators.

    Science.gov (United States)

    Zhao, Jianxun; Lu, Hongmin; Deng, Jun

    2015-02-01

    The planar-scanning technique was applied to the experimental measurement of the electric field and power flux density (PFD) in the exposure area close to the millimeter-wave (MMW) radiator. In the near-field region, the field and PFD were calculated from the plane-wave spectrum of the field sampled on a scan plane far from the radiator. The measurement resolution was improved by reducing the spatial interval between the field samples to a fraction of half the wavelength and implementing multiple iterations of the fast Fourier transform. With the reference to the results from the numerical calculation, an experimental evaluation of the planar-scanning measurement was made for a 50 GHz radiator. Placing the probe 1 to 3 wavelengths from the aperture of the radiator, the direct measurement gave the near-field data with significant differences from the numerical results. The planar-scanning measurement placed the probe 9 wavelengths away from the aperture and effectively reduced the maximum and averaged differences in the near-field data by 70.6% and 65.5%, respectively. Applied to the dosimetry of an open-ended waveguide and a choke ring antenna for 60 GHz exposure, the technique proved useful to the measurement of the PFD in the near-field exposure area of MMW radiators.

  17. Mean Field Games for Stochastic Growth with Relative Utility

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Minyi, E-mail: mhuang@math.carleton.ca [Carleton University, School of Mathematics and Statistics (Canada); Nguyen, Son Luu, E-mail: sonluu.nguyen@upr.edu [University of Puerto Rico, Department of Mathematics (United States)

    2016-12-15

    This paper considers continuous time stochastic growth-consumption optimization in a mean field game setting. The individual capital stock evolution is determined by a Cobb–Douglas production function, consumption and stochastic depreciation. The individual utility functional combines an own utility and a relative utility with respect to the population. The use of the relative utility reflects human psychology, leading to a natural pattern of mean field interaction. The fixed point equation of the mean field game is derived with the aid of some ordinary differential equations. Due to the relative utility interaction, our performance analysis depends on some ratio based approximation error estimate.

  18. Computational dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Siebert, B.R.L.; Thomas, R.H.

    1996-01-01

    The paper presents a definition of the term ``Computational Dosimetry`` that is interpreted as the sub-discipline of computational physics which is devoted to radiation metrology. It is shown that computational dosimetry is more than a mere collection of computational methods. Computational simulations directed at basic understanding and modelling are important tools provided by computational dosimetry, while another very important application is the support that it can give to the design, optimization and analysis of experiments. However, the primary task of computational dosimetry is to reduce the variance in the determination of absorbed dose (and its related quantities), for example in the disciplines of radiological protection and radiation therapy. In this paper emphasis is given to the discussion of potential pitfalls in the applications of computational dosimetry and recommendations are given for their avoidance. The need for comparison of calculated and experimental data whenever possible is strongly stressed.

  19. Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams.

    Science.gov (United States)

    Sánchez-Doblado, F; Andreo, P; Capote, R; Leal, A; Perucha, M; Arráns, R; Núñez, L; Mainegra, E; Lagares, J I; Carrasco, E

    2003-07-21

    Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm2 beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix (delta = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm2 fields. For radiosurgery applicators and narrow MLC beams, the calculated s(w,air) values agree with the reference within +/-0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s(w,air) agrees within 0.1% with the value for 10 x 10 cm2, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24 MV) the difference in s

  20. Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Doblado, F [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Andreo, P [Division of Medical Radiation Physics, University of Stockholm, Karolinska Institute, PO Box 260, SE-171 76 Stockholm (Sweden); Capote, R [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Leal, A [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Perucha, M [Dpto Fisica Medica y Biofisica, F Medicina, Universidad Sevilla (Spain); Arrans, R [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Nunez, L [Radiofisica, Clinica Puerta de Hierro, Madrid (Spain); Mainegra, E [National Research Council, Ottawa (Canada); Lagares, J I [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain); Carrasco, E [Radiofisica, Hospital Univ Virgen Macarena, Avda Dr Fedriani s/n, E-41009 Sevilla (Spain)

    2003-07-21

    Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm{sup 2} beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix ({delta} = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm{sup 2} fields. For radiosurgery applicators and narrow MLC beams, the calculated s{sub w,air} values agree with the reference within {+-}0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s{sub w,air} agrees within 0.1% with the value for 10 x 10 cm{sup 2}, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24

  1. Utilizing Urban Environments for Effective Field Experiences

    Science.gov (United States)

    MacAvoy, S. E.; Knee, K.

    2014-12-01

    Research surveys suggest that students are demanding more applied field experiences from their undergraduate environmental science programs. For geoscience educators at liberal arts colleges without field camps, university vehicles, or even geology departments, getting students into the field is especially rewarding - and especially challenging. Here, we present strategies that we have used in courses ranging from introductory environmental science for non-majors, to upper level environmental methods and geology classes. Urban locations provide an opportunity for a different type of local "field-work" than would otherwise be available. In the upper-level undergraduate Environmental Methods class, we relied on a National Park area located a 10-minute walk from campus for most field exercises. Activities included soil analysis, measuring stream flow and water quality parameters, dendrochronology, and aquatic microbe metabolism. In the non-majors class, we make use of our urban location to contrast water quality in parks and highly channelized urban streams. Here we share detailed lesson plans and budgets for field activities that can be completed during a class period of 2.5 hours with a $75 course fee, show how these activities help students gain quantitative competency, and provide student feedback about the classes and activities.

  2. Dosimetry for small fields in stereotactic radiosurgery using gafchromic MD-V2-55 film, TLD-100 and alanine dosimeters.

    Directory of Open Access Journals (Sweden)

    Guerda Massillon-J L

    Full Text Available This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK and a modified linear accelerator (linac for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55, alanine and thermoluminescent (TLD-100 dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in (60Co gamma-ray and 6 MV x-ray reference (10×10 cm(2 fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not

  3. Dosimetry Service

    CERN Multimedia

    Dosimetry Service

    2005-01-01

    Please remember to read your dosimeter at least once every month. A regular read-out is indispensable to ensure periodic monitoring of your personal dose. You must read your dosimeter even if you have not visited the controlled areas. Film badges are no longer valid at CERN and holders of film badges are no longer allowed to enter the controlled radiation areas or work with a source. Dosimetry Service Tel. 72155 http://cern.ch/rp-dosimetry

  4. Use of novel fibre-coupled radioluminescence and RADPOS dosimetry systems for total scatter factor measurements in small fields

    DEFF Research Database (Denmark)

    Ploquin, N.; Kertzscher, Gustavo; Vandervoort, E.

    2015-01-01

    for the RL detector response for the 5, 7.5 and 10 mm collimators in order to correct for the detector geometry and increased photoelectric cross section of Al2O3:C relative to water. For comparison, measurements were also carried out using a micro MOSFET, PTW60012 diode and GAFCHROMIC® film (EBT and EBT2......). Uncorrected (Sc,p)fclindet, were obtained by taking the ratio of the detector response for each collimator to that for the 60 mm diameter reference field. Published Monte Carlo calculated correction factors were applied to the RADPOS, microMOSFET and diode detector measurements to yield corrected field...... factors, Ωfclin,fmsrQclin,Qmsrfollowing the terminology of a recent formalism introduced for small and composite field relative dosimetry. With corrections, the RL measured Ωfclin,fmsrQclin,Qmsr were 0.656 ± 0.002, 0.815 ± 0.002 and 0.865 ± 0.003 for the 5, 7.5 and 10 mm collimators, respectively...

  5. Field calibration of PADC track etch detectors for local neutron dosimetry in man using different radiation qualities

    Energy Technology Data Exchange (ETDEWEB)

    Haelg, Roger A., E-mail: rhaelg@phys.ethz.ch [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Besserer, Juergen [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Boschung, Markus; Mayer, Sabine [Division for Radiation Safety and Security, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Clasie, Benjamin [Department of Radiation Oncology, Massachusetts General Hospital, 30 Fruit Street, Boston, MA 02114 (United States); Kry, Stephen F. [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Schneider, Uwe [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 204, CH-8057 Zurich (Switzerland)

    2012-12-01

    In order to quantify the dose from neutrons to a patient for contemporary radiation treatment techniques, measurements inside phantoms, representing the patient, are necessary. Published reports on neutron dose measurements cover measurements performed free in air or on the surface of phantoms and the doses are expressed in terms of personal dose equivalent or ambient dose equivalent. This study focuses on measurements of local neutron doses inside a radiotherapy phantom and presents a field calibration procedure for PADC track etch detectors. An initial absolute calibration factor in terms of H{sub p}(10) for personal dosimetry is converted into neutron dose equivalent and additional calibration factors are derived to account for the spectral changes in the neutron fluence for different radiation therapy beam qualities and depths in the phantom. The neutron spectra used for the calculation of the calibration factors are determined in different depths by Monte Carlo simulations for the investigated radiation qualities. These spectra are used together with the energy dependent response function of the PADC detectors to account for the spectral changes in the neutron fluence. The resulting total calibration factors are 0.76 for a photon beam (in- and out-of-field), 1.00 (in-field) and 0.84 (out-of-field) for an active proton beam and 1.05 (in-field) and 0.91 (out-of-field) for a passive proton beam, respectively. The uncertainty for neutron dose measurements using this field calibration method is less than 40%. The extended calibration procedure presented in this work showed that it is possible to use PADC track etch detectors for measurements of local neutron dose equivalent inside anthropomorphic phantoms by accounting for spectral changes in the neutron fluence.

  6. Epid Dosimetry

    Science.gov (United States)

    Greer, Peter B.; Vial, Philip

    2011-05-01

    Electronic portal imaging devices (EPIDs) were introduced originally for patient position verification. The idea of using EPIDs for dosimetry was realised in the 1980s. Little was published on the topic until the mid 1990's, when the interest in EPIDs for dosimetry increased rapidly and continues to grow. The increasing research on EPID dosimetry coincided with the introduction of intensity modulated radiation therapy (IMRT). EPIDs are well suited to IMRT dosimetry because they are high resolution, two-dimensional (2D) digital detectors. They are also pre-existing on almost all modern linear accelerators. They generally show a linear response to increasing dose. Different types of EPIDs have been clinically implemented, and these have been described in several review papers. The current generation of commercially available EPIDs are indirect detection active matrix flat panel imagers, also known as amorphous silicon (a-Si) EPIDs. Disadvantages of a-Si EPIDs for dosimetry include non-water equivalent construction materials, and the energy sensitivity and optical scatter of the phosphor scintillators used to create optical signal from the megavoltage beam. This report discusses current knowledge regarding a-Si EPIDs for dosimetry.

  7. Field Science--the Nature and Utility of Scientific Fields.

    Science.gov (United States)

    Casadevall, Arturo; Fang, Ferric C

    2015-09-08

    Fields are the fundamental sociological units of science. Despite their importance, relatively little has been written about their emergence, composition, structure, and function in the scientific enterprise. This essay considers the nature of fields and their important role in maintaining information and providing normative standards for scientific work. We suggest that fields arise naturally as a consequence of increasing information and scientific specialization. New fields tend to emerge as research communities grow, which may reflect biologically determined optima for the size of human groups. The benefits of fields include the organization of scientists with similar interests into communities that collectively define the next important problems to pursue. In the discipline of microbiology, fields are often organized on the basis of phylogenetic differences between microorganisms being studied. Although fields are essential to the proper functioning of science, their emergence can restrict access by outsiders and sustain dogmas that hinder progress. We suggest mechanisms to improve the functioning of scientific fields and to promote interdisciplinary interaction between fields.

  8. Compounds of 6Li and natural Li for EPR dosimetry in photon/neutron mixed radiation fields.

    Science.gov (United States)

    Lund, E; Gustafsson, H; Danilczuk, M; Sastry, M D; Lund, A

    2004-05-01

    Formates and dithionates of 6Li, enriched and 7Li in natural composition of Li offer a possibility to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field for instance at a boron neutron capture therapy (BNCT) facility. Tests with formates and dithionates of enriched 6Li and lithium compounds with natural composition have been performed at the BNCT facility at Studsvik, Sweden. Irradiations have been performed at 3 cm depth in a Perspex phantom in a fluence rate of thermal neutrons 1.8 x 10(9) n cm(-2) s(-1). The compounds were also irradiated in a pure X-ray field from a 4MV linear accelerator at 5 cm depth in a phantom with accurately determined absorbed doses. The signal intensity and shape was investigated within 3 h after the irradiation. A single line spectrum attributed to the CO2- radical was observed after irradiation of lithium formate. An increase in line width occurring after neutron irradiation in comparison with photon irradiation of the 6Li sample was attributed to dipolar broadening between CO2- radicals trapped in the tracks of the alpha particles. A spectrum due to the SO3- radical anion was observed after irradiation of lithium dithionate. The signal amplitude increased using the 6Li in place of the Li with natural composition of isotopes, in studies with low energy X-ray irradiation. Due to the decreased line width, caused by the difference in g(N) and I between the isotopes, the sensitivity with 6Li dithionate may be enhanced by an order of magnitude compared to alanine dosimetry. After comprehensive examination of the different combinations of compounds with different amounts of 6Li and 7Li regarding dosimetry, radiation chemistry and EPR properties these dosimeter material might be used for dose determinations at BNCT treatments and for biomedical experiments. Interesting properties of the radical formation might be visible due to the large difference in ionization density of neutrons compared to photons.

  9. Tissue interfaces dosimetry in small field radiotherapy with alanine/EPR mini dosimeters and Monte Carlo-Penelope simulation

    Energy Technology Data Exchange (ETDEWEB)

    Vega R, J. L.; Nicolucci, P.; Baffa, O. [Universidade de Sao Paulo, FFCLRP, Departamento de Fisica, Av. Bandeirantes 3900, Bairro Monte Alegre, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Chen, F. [Universidade Federale do ABC, CCNH, Rua Santa Adelia 166, Bangu, 09210-170 Santo Andre, Sao Paulo (Brazil); Apaza V, D. G., E-mail: josevegaramirez@yahoo.es [Universidad Nacional de San Agustin de Arequipa, Departamento de Fisica, Arequipa (Peru)

    2014-08-15

    The dosimetry system based on alanine mini dosimeters plus K-Band EPR spectrometer was tested in the tissue-interface dosimetry through the percentage depth-dose (Pdd) determination for 3 x 3 cm{sup 2} and 1 x 1 cm{sup 2} radiation fields sizes. The alanine mini dosimeters were produced by mechanical pressure from a mixture of 95% L-alanine and 5% polyvinyl alcohol (Pva) acting as binder. Nominal dimensions of these mini dosimeters were 1 mm diameter and 3 mm length as well as 3 - 4 mg mass. The EPR spectra of the mini dosimeters were registered using a K-Band (24 GHz) EPR spectrometer. The mini dosimeters were placed in a nonhomogeneous phantom and irradiated with 20 Gy in a 6 MV PRIMUS Siemens linear accelerator, with a source-to-surface distance of 100 cm using the small fields previously mentioned. The cylindrical non-homogeneous phantom was comprised of several disk-shaped plates of different materials in the sequence acrylic-bone cork-bone-acrylic, with dimensions 15 cm diameter and 1 cm thick. The plates were placed in descending order, starting from top with four acrylic plates followed by two bone plates plus eight cork plates plus two bone plates and finally, four acrylic plates (4-2-8-2-4). Pdd curves from the treatment planning system and from Monte Carlo simulation with Penelope code were determined. Mini dosimeters Pdd results show good agreement with Penelope, better than 95% for the cork homogeneous region and 97.7% in the bone heterogeneous region. In the first interface region, between acrylic and bone, it can see a dose increment of 0.6% for mini dosimeters compared to Penelope. At the second interface, between bone and cork, there is 9.1% of dose increment for mini dosimeter relative to Penelope. For the third (cork-bone) and fourth (bone-acrylic) interfaces, the dose increment for mini dosimeters compared to Penelope was 4.1% both. (Author)

  10. Correction factors for A1SL ionization chamber dosimetry in TomoTherapy: Machine-specific, plan-class, and clinical fields

    Energy Technology Data Exchange (ETDEWEB)

    Gago-Arias, Araceli; Rodriguez-Romero, Ruth; Sanchez-Rubio, Patricia; Miguel Gonzalez-Castano, Diego; Gomez, Faustino; Nunez, Luis; Palmans, Hugo; Sharpe, Peter; Pardo-Montero, Juan [Departamento de Fisica de Particulas, Facultad de Fisica, Universidad de Santiago de Compostela (Spain); Servicio de Radiofisica, Hospital Universitario Puerta de Hierro, Madrid 28222 (Spain); Departamento de Fisica de Particulas, Facultad de Fisica, Universidad de Santiago de Compostela, 15782 (Spain) and Radiation Physics Laboratory, Universidad de Santiago de Compostela, 15782 (Spain); Servicio de Radiofisica, Hospital Universitario Puerta de Hierro, Madrid, 28222 (Spain); National Physical Laboratory, Teddington, Middx, TW11 OLW (United Kingdom); Departamento de Fisica de Particulas, Facultad de Fisica, Universidad de Santiago de Compostela, 15782 (Spain)

    2012-04-15

    Purpose: Recently, an international working group on nonstandard fields presented a new formalism for ionization chamber reference dosimetry of small and nonstandard fields [Alfonso et al., Med. Phys. 35, 5179-5186 (2008)] which has been adopted by AAPM TG-148. This work presents an experimental determination of the correction factors for reference dosimetry with an Exradin A1SL thimble ionization chamber in a TomoTherapy unit, focusing on: (i) machine-specific reference field, (ii) plan-class-specific reference field, and (iii) two clinical treatments. Methods: Ionization chamber measurements were performed in the TomoTherapy unit for intermediate (machine-specific and plan-class-specific) calibration fields, based on the reference conditions defined by AAPM TG-148, and two clinical treatments (lung and head-and-neck). Alanine reference dosimetry was employed to determine absorbed dose to water at the point of interest for the fields under investigation. The corresponding chamber correction factors were calculated from alanine to ionization chamber measurements ratios. Results: Two different methods of determining the beam quality correction factor k{sub Q,Q{sub 0}} for the A1SL ionization chamber in this TomoTherapy unit, where reference conditions for conventional beam quality determination cannot be met, result in consistent values. The observed values of overall correction factors obtained for intermediate and clinical fields are consistently around 0.98 with a typical expanded relative uncertainty of 2% (k = 2), which when considered make such correction factors compatible with unity. However, all of them are systematically lower than unity, which is shown to be significant when a hypothesis test assuming a t-student distribution is performed (p=1.8x10{sup -2}). Correction factors k{sub Q{sub c{sub l{sub i{sub n,Q{sub p{sub c{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub p}{sub c}{sub s}{sub r}}}}}}}}}} and k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s

  11. On the Monte Carlo simulation of small-field micro-diamond detectors for megavoltage photon dosimetry

    Science.gov (United States)

    Andreo, Pedro; Palmans, Hugo; Marteinsdóttir, Maria; Benmakhlouf, Hamza; Carlsson-Tedgren, Åsa

    2016-01-01

    Monte Carlo (MC) calculated detector-specific output correction factors for small photon beam dosimetry are commonly used in clinical practice. The technique, with a geometry description based on manufacturer blueprints, offers certain advantages over experimentally determined values but is not free of weaknesses. Independent MC calculations of output correction factors for a PTW-60019 micro-diamond detector were made using the EGSnrc and PENELOPE systems. Compared with published experimental data the MC results showed substantial disagreement for the smallest field size simulated (5~\\text{mm}× 5 mm). To explain the difference between the two datasets, a detector was imaged with x rays searching for possible anomalies in the detector construction or details not included in the blueprints. A discrepancy between the dimension stated in the blueprints for the active detector area and that estimated from the electrical contact seen in the x-ray image was observed. Calculations were repeated using the estimate of a smaller volume, leading to results in excellent agreement with the experimental data. MC users should become aware of the potential differences between the design blueprints of a detector and its manufacturer production, as they may differ substantially. The constraint is applicable to the simulation of any detector type. Comparison with experimental data should be used to reveal geometrical inconsistencies and details not included in technical drawings, in addition to the well-known QA procedure of detector x-ray imaging.

  12. Agricultural field reclamation utilizing native grass crop production

    Science.gov (United States)

    J. Cure

    2013-01-01

    Developing a method of agricultural field reclamation to native grasses in the Lower San Pedro Watershed could prove to be a valuable tool for educational and practical purposes. Agricultural field reclamation utilizing native grass crop production will address water table depletion, soil degradation and the economic viability of the communities within the watershed....

  13. Dosimetry of Exposure to Electromagnetic Fields in Daily Life and Medical Applications

    NARCIS (Netherlands)

    J.F. Bakker (Jurriaan)

    2012-01-01

    textabstractElectromagnetic fields (EMF) are present everywhere in our environment but are usually invisible to the human eye. EMF for example generated by mobile phones and 50Hz power lines, can cause electric fields, currents and tissue heating in the human body. In the past, exposure limits were

  14. THERMOLUMINESCENT DOSIMETRY

    African Journals Online (AJOL)

    2005-10-20

    Oct 20, 2005 ... abo area of the city has the least radiation dose rate while Obantoku area has the upper limit. aking this as ... 'n Abeokuta. eywords: Environmental radiation, thermoluminescent dosimetry, Abeokuta, outdoor ... Both 238U and 232Th have long decay series with ... effects of radiation exposure (Hanson and.

  15. THERMOLUMINESCENT DOSIMETRY

    African Journals Online (AJOL)

    2005-10-20

    Oct 20, 2005 ... abo area of the city has the least radiation dose rate while Obantoku area has the upper limit. aking this as ... “n Abeokuta. eywords: Environmental radiation, thermoluminescent dosimetry, Abeokuta, outdoor ... Both 238U and 232Th have long decay series with ... effects of radiation exposure (Hanson and.

  16. The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, T., E-mail: schmito@uni-mainz.de [Institute for nuclear chemistry, Johannes Gutenberg-University, Mainz D-55128 (Germany); Bassler, N. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Aarhus C, Aarhus 8000 (Denmark); Blaickner, M. [AIT Austrian Institute of Technology GmbH, Vienna A-1220 (Austria); Ziegner, M. [AIT Austrian Institute of Technology GmbH, Vienna A-1220, Austria and TU Wien, Vienna University of Technology, Vienna A-1020 (Austria); Hsiao, M. C. [Insitute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liu, Y. H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Koivunoro, H. [Department of Physics, University of Helsinki, POB 64, FI-00014, Finland and HUS Medical Imaging Center, Helsinki University Central Hospital, FI-00029 HUS (Finland); Auterinen, I.; Serén, T.; Kotiluoto, P. [VTT Technical Research Centre of Finland, Espoo (Finland); Palmans, H. [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW, United Kingdom and Medical Physics Group, EBG MedAustron GmbH, Wiener Neustadt A-2700 (Austria); Sharpe, P. [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW (United Kingdom); Langguth, P. [Department of Pharmacy and Toxicology, University of Mainz, Mainz D-55128 (Germany); Hampel, G. [Institut für Kernchemie, Johannes Gutenberg-Universität, Mainz D-55128 (Germany)

    2015-01-15

    Purpose: The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Methods: Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a {sup 60}Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes FLUKA and MCNP. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen and Olsen alanine response model. Results: The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields. Conclusions: The

  17. Dosimetry of an accident in mixed field (neutrons, photons) using the spectrometry by electronic paramagnetic resonance(EPR); Dosimetrie d'accident en champ mixte (neutrons, photons) utilisant la spectrometrie par resonance paramagnetique electronique (RPE)

    Energy Technology Data Exchange (ETDEWEB)

    Herve, M.L

    2006-03-15

    In a radiological accident, the assessment of the dose received by the victim is relevant information for the therapeutic strategy. Two complementary dosimetric techniques based on physical means are used in routine practice in the laboratory: EPR spectroscopy performed on materials removed from the victim or gathered from the vicinity of the victim and Monte Carlo calculations. EPR dosimetry, has been used successfully several times in cases of photon or electron overexposures. Accidental exposure may also occur with a neutron component. The aim of this work is to investigate the potentiality of EPR dosimetry for mixed photon and neutron field exposure with different organic materials (ascorbic acid, sorbitol, glucose, galactose, fructose, mannose, lactose and sucrose). The influence of irradiation parameters (dose, dose rate, photon energy) and of environmental parameters (temperature of heating, light exposure) on the EPR signal amplitude was studied. To assess the neutron sensitivity, the materials were exposed to a mixed radiation field of experimental reactors with different neutron to photon ratios. The relative neutron sensitivity was found to range from 10% to 43% according to the materials. Prior knowledge of the ratio between the dose in samples measured by EPR spectrometry and organ or whole body dose obtained by calculations previously performed for these different configurations, makes it possible to give a first estimation of the dose received by the victim in a short delay. The second aim of this work is to provide data relevant for a quick assessment of the dose distribution in case of accidental overexposure based on EPR measurements performed on one or several points of the body. The study consists in determining by calculation the relation between the dose to the organs and whole body and the dose to specific points of the body, like teeth, bones or samples located in the pockets of victim clothes, for different external exposures corresponding

  18. Dosimetry Service

    CERN Multimedia

    Dosimetry Service

    2005-01-01

    Please remember to read your dosimeter every month at least once and preferably during the first week. A regular read-out is indispensable in order to ensure a periodic monitoring of the personal dose. You should read your dosimeter even if you have not visited the controlled areas. If you still have the old dosimeter (film badge), please send it immediately for evaluation to us (Bdg 24 E-011). After January 2005 there will be no developing process for the old film system. Information for Contractors: Please remember also to bring the form ‘Confirm Reception of a CERN Dosimeter' signed with ‘Feuille d'enregistrement du CERN'. Without these forms the dosimeter cannot be assigned. Thank you for your cooperation. Dosimetry Service Tel 767 2155 http://cern.ch/rp-dosimetry

  19. Studies of the Electric Field Distribution in Biological Bodies - Experimental Dosimetry at Radiofrequencies

    Science.gov (United States)

    1985-12-05

    Absorption Rate Distribution In Simple Geometrica ~l Bodies at Radio Frequencies", M.A.Sc. Thesis, University of Ottawa. 24. G.H. Wong, S.S. Stuchly, A...desigted for operaion in air 12,4,51 or in the dielectric media • C2.7] can be used 1: our eysteia lo s a they coo- _ Cl three L-doperdeot aote-ra...dielectric media is detetaled by masuring the output voltage of the electric field probe, placed at varils locacioc 160 me1 208 3.9 NA I= a sphere made of tht

  20. Radiation dosimetry.

    OpenAIRE

    Cameron, J

    1991-01-01

    This article summarizes the basic facts about the measurement of ionizing radiation, usually referred to as radiation dosimetry. The article defines the common radiation quantities and units; gives typical levels of natural radiation and medical exposures; and describes the most important biological effects of radiation and the methods used to measure radiation. Finally, a proposal is made for a new radiation risk unit to make radiation risks more understandable to nonspecialists.

  1. Occupational dosimetry in real time hemodynamic rooms. utility of the system Dose-aware as a training tool; Dosimetria ocupacional en tiempo real en salas de hemodinamica. Utilidad del Sistema Dose-Aware como herramienta formativa

    Energy Technology Data Exchange (ETDEWEB)

    Pinto Monedero, M.; Rodriguez Cobo, C.; Pifarre Martinez, X.; Ruiz Martin, J.; Barros Candelero, J. M.; Goicolea Ruigomez, J.; Diaz Blaires, G.; Garcia Lunar

    2014-02-01

    This paper presents the results from a study in a real time dosimetry system used in the catheter laboratory room of our center. The objective was to know the occupational doses per procedure, on the one hand, and, on the other hand, to evaluate its utility as a learning tool for radiation protection purposes with the simultaneous video recording of the interventions. 83 diagnostic and therapeutic procedures were analyzed, and an average dose per procedure of 0,37 {mu}Sv and 0,10 {mu}Sv for the main cardiologist and nurse were obtained, respectively. 36 of these interventions were also recorded and the images were synchronized with the dosimetric information stored and the dosimetry system. The findings were presented to the interventional cardiology team in a learning session. They showed a high level of satisfaction with this new method of optimizing the occupational doses through a customized learning session. (Author)

  2. Dosimetry for the MRI accelerator: the impact of a magnetic field on the response of a Farmer NE2571 ionization chamber.

    Science.gov (United States)

    Meijsing, I; Raaymakers, B W; Raaijmakers, A J E; Kok, J G M; Hogeweg, L; Liu, B; Lagendijk, J J W

    2009-05-21

    The UMC Utrecht is constructing a 1.5 T MRI scanner integrated with a linear accelerator (Lagendijk et al 2008 Radiother. Oncol. 86 25-9). The goal of this device is to facilitate soft-tissue contrast based image-guided radiotherapy, in order to escalate the dose to the tumour while sparing surrounding normal tissues. Dosimetry for the MRI accelerator has to be performed in the presence of a magnetic field. This paper investigates the feasibility of using a Farmer NE2571 ionization chamber for absolute dosimetry. The impact of the mcagnetic field on the response of this ionization chamber has been measured and simulated using GEANT4 Monte Carlo simulations. Two orientations of the ionization chamber with respect to the incident beam and the magnetic field which are feasible in the MRI accelerator configuration are taken into account. Measurements are performed using a laboratory magnet ranging from 0 to 1.2 T. In the simulations a range from 0 to 2 T is used. For both orientations, the measurements and simulations agreed within the uncertainty of the measurements and simulations. In conclusion, the response of the ionization chamber as a function of the magnetic field is understood and can be simulated using GEANT4 Monte Carlo simulations.

  3. Mixed field personnel dosimetry using a nearly tissue-equivalent multi-element thermoluminescence dosemeter

    Energy Technology Data Exchange (ETDEWEB)

    Moscovitch, M.; Velbeck, K.J.; Bencke, G.M. (Engelhard Corp., Harshaw Crystal and Electronic Products, Solon, OH (USA))

    1990-01-01

    The method of response interpretation for determining dose equivalents of a new multi-element thermoluminescence dosemeter in mixed photon-beta and photon-neutron fields is described. The four TL chips are LiF:Mg,Ti, each covered by its own unique filter. Experiments to determine the response of the dosemeter and to test the dose calculation algorithm were performed according to the standard established by the US Department of Energy Laboratory Accreditation Program (DOELAP). It has been shown that the dosemeter response can be used to identify the mixture type. The accuracy of the system has been proven in blind testing to be well within DOELAP tolerance limits in all test categories. (author).

  4. Dosimetry analysis of small radiation fields in stereotactic radiosurgery of the brain

    Science.gov (United States)

    Al-Najjar, Waleed Hassan

    Accurate dosimetric data of narrow circular photon beams are needed for stereotactic radiosurgery of brain tumors. However, the measurement of dosimetric data of narrow circular beams is beset with several constraints. Usually, 6 MV photon beams produced by isocentric linear accelerators are mostly used for routine radiosurgery although other photon energies are available. Systematic dosimetric studies were performed on 12.5, 20, 30 and 40 mm diameter collimators using different measuring techniques in order to examine the possible accuracies associated in the measured dosimetric data of narrow circular photon beams. In addition, the relative suitabilities of 4, 6 and 10 MV photon beams for stereotactic radiosurgery were assessed. The lack of electronic equilibrium and steep dose gradient effects were found to be minimal for a 4 MV photon beam compared to the 6 and 10 MV photon beams. The measured output factors with a small volume (0.02 cc) ionization chamber were found to agree with film and MOSFET (Metal Oxide Semiconductor Field Effect Transistor) detector measurements for 4 MV photon beam even for smaller field sizes. The measured beam profiles were also found to be in better agreement with the expected shapes for the 4 MV beam than for 6 and 10 MV beams. The 80% isodose volumes for a typical 20.0 mm diameter field for 1 to 10 non-coplanar converging arcs showed that the volumes for the 4 MV beam are slightly larger than the corresponding volumes for the 6 and 10 MV photon beams for any given isodose level. The dose fall- off distances from the 80% to 50% isodoses are also, in general, found to be smaller for the 4 MV beam. Therefore, for radiosurgery, the dose calculations for the 4 MV beam have less uncertainty than the dose calculations for the 6 and 10 MV beams. The output factors can be measured with an ionization chamber for the 4 MV photon beam over the range 12.5 to 40.0 mm diameter field size, whereas for the 6 MV beam they can only be measured for

  5. Near-field dosimetry for in vitro exposure of human cells at 60 GHz.

    Science.gov (United States)

    Zhadobov, Maxim; Sauleau, Ronan; Augustine, Robin; Le Quément, Catherine; Le Dréan, Yves; Thouroude, Daniel

    2012-01-01

    Due to the expected mass deployment of millimeter-wave wireless technologies, thresholds of potential millimeter-wave-induced biological and health effects should be carefully assessed. The main purpose of this study is to propose, optimize, and characterize a near-field exposure configuration allowing illumination of cells in vitro at 60 GHz with power densities up to several tens of mW/cm(2) . Positioning of a tissue culture plate containing cells has been optimized in the near-field of a standard horn antenna operating at 60 GHz. The optimal position corresponds to the maximal mean-to-peak specific absorption rate (SAR) ratio over the cell monolayer, allowing the achievement of power densities up to 50 mW/cm(2) at least. Three complementary parameters have been determined and analyzed for the exposed cells, namely the power density, SAR, and temperature dynamics. The incident power density and SAR have been computed using the finite-difference time-domain (FDTD) method. The temperature dynamics at different locations inside the culture medium are measured and analyzed for various power densities. Local SAR, determined based on the initial rate of temperature rise, is in a good agreement with the computed SAR (maximal difference of 5%). For the optimized exposure setup configuration, 73% of cells are located within the ±3 dB region with respect to the average SAR. It is shown that under the considered exposure conditions, the maximal power density, local SAR, and temperature increments equal 57 mW/cm(2) , 1.4 kW/kg, and 6 °C, respectively, for the radiated power of 425 mW.

  6. Hybrid nanostructured thin-films by PLD for enhanced field emission performance for radiation micro-nano dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, E., E-mail: maniphysics@gmail.com [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); Materials Science Group (MSG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Corrosion Science and Technology Group, Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Sree Balaji Medical College & Hospital (SBMCH), Bharath University, Chrompet, Chennai 600044 (India); Kennedy, J. [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Kavitha, G. [UNESCO-UNISA AFNET in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), Materials Research Department, iThemba LABS–National Research Foundation (NRF), 1 Old Faure Road, Somerset West, PO Box 722, Western Cape (South Africa); PG& Research Dept of Physics, AM Jain College Affiliated to University of Madras, Chennai 600114 (India); and others

    2015-10-25

    We report the observation of hybrid nanostructured thin-films such as diamond-like carbon (DLC) signature on the ZnO epitaxial thin-films grown onto the device silicon/quartz substrate by reactive pulsed laser deposition (r-PLD) under the argon–oxygen (Ar|O{sub 2}) ambient at 573 K. Undoped and Carbon (C) doped epitaxial ZnO thin-film layer formation is revealed by the accelerator based ion-beam analysis (IBA) technique of resonant Rutherford backscattering spectrometry (RRBS), glancing-incidence X-ray diffraction (GIXRD) pattern, micro-Raman spectroscopy (μ-RS) and field-emission (F-E) studies. The RRBS and GIXRD results show the deposition of epitaxial thin-films containing C into ZnO. The μ-RS technique is a standard nondestructive tool (NDT) for the characterization of crystalline, nano-crystalline, and amorphous carbons (a-C). As grown ZnO and C-doped ZnO thin-films μ-RS result reveal the doping effect of C-impurities that appear in the form of DLC evident from Raman peaks at 1357 and 1575 cm{sup −1} along with a wurtzite structure peak at 438 cm{sup −1} with E{sub 2}(h) phonon of ZnO. The electron transport F-E result shows the hybrid thin-films has high conductivity than the un-doped film. Fabricated hybrid nanostructured thin-films materials could be very useful for the emerging applications of micro-nano dosimetry. - Highlights: • Observation of hybrid nanostructured diamond-like carbon (DLC) on ZnO epitaxial thin-films at 573 K. • Carbon doped epitaxial ZnO thin-film layer formation is revealed by RRBS, Micro-Raman. • Field-emission (F-E) study. • DLC formation evident from Raman peaks at 1357 and 1575 cm{sup −1} along with a wurtzite structure peak of ZnO. • The electron transport F-E result shows the hybrid thin-film has high conductivity than the undoped thin-film.

  7. Monte Carlo simulation of mixed neutron-gamma radiation fields and dosimetry devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoqing

    2011-12-22

    Monte Carlo methods based on random sampling are widely used in different fields for the capability of solving problems with a large number of coupled degrees of freedom. In this work, Monte Carlos methods are successfully applied for the simulation of the mixed neutron-gamma field in an interim storage facility and neutron dosimeters of different types. Details are discussed in two parts: In the first part, the method of simulating an interim storage facility loaded with CASTORs is presented. The size of a CASTOR is rather large (several meters) and the CASTOR wall is very thick (tens of centimeters). Obtaining the results of dose rates outside a CASTOR with reasonable errors costs usually hours or even days. For the simulation of a large amount of CASTORs in an interim storage facility, it needs weeks or even months to finish a calculation. Variance reduction techniques were used to reduce the calculation time and to achieve reasonable relative errors. Source clones were applied to avoid unnecessary repeated calculations. In addition, the simulations were performed on a cluster system. With the calculation techniques discussed above, the efficiencies of calculations can be improved evidently. In the second part, the methods of simulating the response of neutron dosimeters are presented. An Alnor albedo dosimeter was modelled in MCNP, and it has been simulated in the facility to calculate the calibration factor to get the evaluated response to a Cf-252 source. The angular response of Makrofol detectors to fast neutrons has also been investigated. As a kind of SSNTD, Makrofol can detect fast neutrons by recording the neutron induced heavy charged recoils. To obtain the information of charged recoils, general-purpose Monte Carlo codes were used for transporting incident neutrons. The response of Makrofol to fast neutrons is dependent on several factors. Based on the parameters which affect the track revealing, the formation of visible tracks was determined. For

  8. Advances in nuclear particle dosimetry for radiation protection and medicine - Ninth Symposium on Neutron Dosimetry (Editorial Material, English)

    Energy Technology Data Exchange (ETDEWEB)

    Zoetelief, J; Bos, A J.; Schuhmacher, H; McDonald, Joseph C.; Schultz, F W.; Pihet, P

    2004-12-15

    The Ninth Symposium on Neutron Dosimetry has been expanded to cover not only neutron radiation but heavy charged particle dosimetry as well. The applications are found in such fields as radiation protection, aircrew dosimetry, medicine, nuclear power and accelerator health physics. Scientists from many countries from around the world presented their work, and described the latest developments in techniques and instrumentation.

  9. In-vivo dosimetry for field sizes down to 6 × 6 mm2 in shaped beam radiosurgery with microMOSFET.

    Science.gov (United States)

    Sors, A; Cassol, E; Latorzeff, I; Duthil, P; Sabatier, J; Lotterie, J A; Redon, A; Berry, I; Franceries, X

    2014-09-01

    The aim of this study is to evaluate microMOSFET as in-vivo dosimeter in 6 MV shaped-beam radiosurgery for field sizes down to 6 × 6 mm2. A homemade build-up cap was developed and its use with microMOSFET was evaluated down to 6 × 6 mm2. The study with the homemade build-up cap was performed considering its influence on field size over-cover occurring at surface, achievement of the overall process of electronic equilibrium, dose deposition along beam axis and dose attenuation. An optimized calibration method has been validated using MOSFET in shaped-beam radiosurgery for field sizes from 98 × 98 down to 18 × 18 mm2. The method was detailed in a previous study and validated in irregular field shapes series measurements performed on a head phantom. The optimized calibration method was applied to microMOSFET equipped with homemade build-up cap down to 6 × 6 mm2. Using the same irregular field shapes, dose measurements were performed on head phantom. MicroMOSFET results were compared to previous MOSFET ones. Additional irregular field shapes down to 8.8 × 8.8 mm2 were studied with microMOSFET. Isocenter dose attenuation due to the homemade build-up cap over the microMOSFET was near 2% irrespective of field size. Our results suggested that microMOSFET equipped with homemade build-up cap is suitable for in-vivo dosimetry in shaped-beam radiosurgery for field sizes down to 6 × 6 mm2 and therefore that the required build-up cap dimensions to perform entrance in-vivo dosimetry in small-fields have to ensure only partial charge particle equilibrium.

  10. Dosimetry of electromagnetic fields for compliance of radiological safety standards; Dosimetria de campos electromagneticos para el cumplimiento de normativas de seguridad radiologica

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, M.

    2005-07-01

    The non-ionizing radiation in occupational, public or residential environments shows a wide variety of characteristics regarding its frequency, power, time pattern, orientation, etc. For a correct dosimetry, it is necessary to choose among diverse measurements protocols and equipment: broadband equipment, selective meters, isotropic probes, high frequency, low frequency, personal monitors, area monitors...How should they be chosen? It depends on the more information available, the easier it will be to take the right decision. For this purpose, it is necessary to understand the physics of the electromagnetic fields (electric field, magnetic field, far and near field) and to be familiar with the corresponding safety limits (occupational or public exposure) in each case. Besides, it is very important to understand the differences between the different technologies used in the modern instrumentation and their applications to specific situations. (Author)

  11. Dosimetry tools and techniques for IMRT.

    Science.gov (United States)

    Low, Daniel A; Moran, Jean M; Dempsey, James F; Dong, Lei; Oldham, Mark

    2011-03-01

    Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly measuring commissioning data and quality assurance (QA) radiation dose distributions. This report provides a comprehensive overview of how dosimeters, phantoms, and dose distribution analysis techniques should be used to support the commissioning and quality assurance requirements of an IMRT program. The proper applications of each dosimeter are described along with the limitations of each system. Point detectors, arrays, film, and electronic portal imagers are discussed with respect to their proper use, along with potential applications of 3D dosimetry. Regardless of the IMRT technique utilized, some situations require the use of multiple detectors for the acquisition of accurate commissioning data. The overall goal of this task group report is to provide a document that aids the physicist in the proper selection and use of the dosimetry tools available for IMRT QA and to provide a resource for physicists that describes dosimetry measurement techniques for purposes of IMRT commissioning and measurement-based characterization or verification of IMRT treatment plans. This report is not intended to provide a comprehensive review of commissioning and QA procedures for IMRT. Instead, this report focuses on the aspects of metrology, particularly the practical aspects of measurements that are unique to IMRT. The metrology of IMRT concerns the application of measurement instruments and their suitability, calibration, and quality control of measurements. Each of the dosimetry measurement tools has limitations that need to be considered when incorporating them into a commissioning process or a comprehensive QA program. For example, routine quality assurance procedures require the use of robust field dosimetry systems. These often exhibit limitations with respect to spatial resolution or energy response and need to themselves be commissioned against more established dosimeters. A chain of

  12. Nuclear accident dosimetry intercomparison studies.

    Science.gov (United States)

    Sims, C S

    1989-09-01

    Twenty-two nuclear accident dosimetry intercomparison studies utilizing the fast-pulse Health Physics Research Reactor at the Oak Ridge National Laboratory have been conducted since 1965. These studies have provided a total of 62 different organizations a forum for discussion of criticality accident dosimetry, an opportunity to test their neutron and gamma-ray dosimetry systems under a variety of simulated criticality accident conditions, and the experience of comparing results with reference dose values as well as with the measured results obtained by others making measurements under identical conditions. Sixty-nine nuclear accidents (27 with unmoderated neutron energy spectra and 42 with eight different shielded spectra) have been simulated in the studies. Neutron doses were in the 0.2-8.5 Gy range and gamma doses in the 0.1-2.0 Gy range. A total of 2,289 dose measurements (1,311 neutron, 978 gamma) were made during the intercomparisons. The primary methods of neutron dosimetry were activation foils, thermoluminescent dosimeters, and blood sodium activation. The main methods of gamma dose measurement were thermoluminescent dosimeters, radiophotoluminescent glass, and film. About 68% of the neutron measurements met the accuracy guidelines (+/- 25%) and about 52% of the gamma measurements met the accuracy criterion (+/- 20%) for accident dosimetry.

  13. Computational dosimetry of induced electric fields during realistic movements in the vicinity of a 3 T MRI scanner.

    Science.gov (United States)

    Laakso, Ilkka; Kännälä, Sami; Jokela, Kari

    2013-04-21

    Medical staff working near magnetic resonance imaging (MRI) scanners are exposed both to the static magnetic field itself and also to electric currents that are induced in the body when the body moves in the magnetic field. However, there are currently limited data available on the induced electric field for realistic movements. This study computationally investigates the movement induced electric fields for realistic movements in the magnetic field of a 3 T MRI scanner. The path of movement near the MRI scanner is based on magnetic field measurements using a coil sensor attached to a human volunteer. Utilizing realistic models for both the motion of the head and the magnetic field of the MRI scanner, the induced fields are computationally determined using the finite-element method for five high-resolution numerical anatomical models. The results show that the time-derivative of the magnetic flux density (dB/dt) is approximately linearly proportional to the induced electric field in the head, independent of the position of the head with respect to the magnet. This supports the use of dB/dt measurements for occupational exposure assessment. For the path of movement considered herein, the spatial maximum of the induced electric field is close to the basic restriction for the peripheral nervous system and exceeds the basic restriction for the central nervous system in the international guidelines. The 99th percentile electric field is a considerably less restrictive metric for the exposure than the spatial maximum electric field; the former is typically 60-70% lower than the latter. However, the 99th percentile electric field may exceed the basic restriction for dB/dt values that can be encountered during tasks commonly performed by MRI workers. It is also shown that the movement-induced eddy currents may reach magnitudes that could electrically stimulate the vestibular system, which could play a significant role in the generation of vertigo-like sensations reported

  14. Dosimetry for radiation processing

    DEFF Research Database (Denmark)

    Miller, Arne

    1986-01-01

    During the past few years significant advances have taken place in the different areas of dosimetry for radiation processing, mainly stimulated by the increased interest in radiation for food preservation, plastic processing and sterilization of medical products. Reference services both...... and sterilization dosimetry, optichromic dosimeters in the shape of small tubes for food processing, and ESR spectroscopy of alanine for reference dosimetry. In this paper the special features of radiation processing dosimetry are discussed, several commonly used dosimeters are reviewed, and factors leading...

  15. Characterization of an electronic system for Image acquisition portal to open field dosimetry; Caracterizacao de um sistema eletronico de aquisicao de imagem portal para dosimetria em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Barbi, Gustavo L.; Oliveira, Harley F.; Bertucci, Edenyse C.; Amaral, Leonardo L.; Borges, Leandro F., E-mail: gustavobarbi@usp.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Hospital das Clinicas. Centro de Ciencias das Imagens e Fisica Medica

    2012-08-15

    The objective was to characterize and enable an electronic portal imaging device (EPID) to use like a portal dosimetry device - PDI, in non-transit mode, without interposition of scattering between the beam and EPID for measurement to open fields. The images as well as the DICOM header data are extracted from software ImageJ and the information are used in the basic algorithm for converting pixel to dose. The linearity and reproducibility of response were analyzed, and the maximum deviation found of 2,3% to 800 monitor units (MU) for linearity and -0,9% for reproducibility of signal measured daily. A 512x512 matrix with a resolution of 0,8mm was established to restore the shape of beam from the image. The field size dependence was evaluated, by obtaining the ratio of total scattering of ionization chamber and EPID. Finally, a calibration factor of 28470.88{+-}170.73 pixel/cGy was established for the central area of the image. Comparative analyzes between the PDI, radiochromic film and array of ionization chambers (MatriXX) showed good agreement for fields greater then 5 x 5 cm{sup 2} to reestablishment of form field and dose, however, for fields between 3x3 cm{sup 2} and 5x5 cm{sup 2}, the agreement to shape of beam was best established by film. (author)

  16. Dosimetry methods in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Artuso, E.; Felisi, M.; Regazzoni, V.; Giove, D. [Universita degli Studi di Milano, Department of Physics, Via Festa del Patrono 7, 20122 Milano (Italy); Agosteo, S.; Barcaglioni, L. [Istituto Nazionale di Fisica Nucleare, Milano (Italy); Campi, F.; Garlati, L. [Politecnico di Milano, Energy Department, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); De Errico, F. [Universita degli Studi di Pisa, Department of Civil and Industrial Engineering, Lungamo Pacinotti 43, 56126 Pisa (Italy); Borroni, M.; Carrara, M. [Fondazione IRCCS Istituto Nazionale Tumori, Medical Physics Unit, Via Venezian 1, 20133 Milano (Italy); Burian, J.; Klupak, V.; Viererbl, L.; Marek, M. [Research Centre Rez, Department of Neutron Physics, 250-68 Husinec-Rez (Czech Republic)

    2014-08-15

    Dosimetry studies have been carried out at thermal and epithermal columns of Lvr-15 research reactor for investigating the spatial distribution of gamma dose, fast neutron dose and thermal neutron fluence. Two different dosimetry methods, both based on solid state detectors, have been studied and applied and the accuracy and consistency of the results have been inspected. One method is based on Fricke gel dosimeters that are dilute water solutions and have good tissue equivalence for neutrons and also for all the secondary radiations produced by neutron interactions in tissue or water phantoms. Fricke gel dosimeters give the possibility of separating the various dose contributions, i.e. the gamma dose, the fast neutron dose and the dose due to charged particles generated during thermal neutron reactions by isotopes having high cross section, like 10-B. From this last dose, thermal neutron fluence can be obtained by means of the kerma factor. The second method is based on thermoluminescence dosimeters. In particular, the developed method draw advantage from the different heights of the peaks of the glow curve of such phosphors when irradiated with photons or with thermal neutrons. The results show that satisfactory results can be obtained with simple methods, in spite of the complexity of the subject. However, the more suitable dosimeters and principally their utilization and analysis modalities are different for the various neutron beams, mainly depending on the relative intensities of the three components of the neutron field, in particular are different for thermal and epithermal columns. (Author)

  17. Monte Carlo modelling of diode detectors for small field MV photon dosimetry: detector model simplification and the sensitivity of correction factors to source parameterization.

    Science.gov (United States)

    Cranmer-Sargison, G; Weston, S; Evans, J A; Sidhu, N P; Thwaites, D I

    2012-08-21

    The goal of this work was to examine the use of simplified diode detector models within a recently proposed Monte Carlo (MC) based small field dosimetry formalism and to investigate the influence of electron source parameterization has on MC calculated correction factors. BEAMnrc was used to model Varian 6 MV jaw-collimated square field sizes down to 0.5 cm. The IBA stereotactic field diode (SFD), PTW T60016 (shielded) and PTW T60017 (un-shielded) diodes were modelled in DOSRZnrc and isocentric output ratios (OR(fclin)(detMC)) calculated at depths of d = 1.5, 5.0 and 10.0 cm. Simplified detector models were then tested by evaluating the percent difference in (OR(fclin)(detMC)) between the simplified and complete detector models. The influence of active volume dimension on simulated output ratio and response factor was also investigated. The sensitivity of each MC calculated replacement correction factor (k(fclin,fmsr)(Qclin,Qmsr)), as a function of electron FWHM between 0.100 and 0.150 cm and energy between 5.5 and 6.5 MeV, was investigated for the same set of small field sizes using the simplified detector models. The SFD diode can be approximated simply as a silicon chip in water, the T60016 shielded diode can be modelled as a chip in water plus the entire shielding geometry and the T60017 unshielded diode as a chip in water plus the filter plate located upstream. The detector-specific (k(fclin,fmsr)(Qclin,Qmsr)), required to correct measured output ratios using the SFD, T60016 and T60017 diode detectors are insensitive to incident electron energy between 5.5 and 6.5 MeV and spot size variation between FWHM = 0.100 and 0.150 cm. Three general conclusions come out of this work: (1) detector models can be simplified to produce OR(fclin)(detMC) to within 1.0% of those calculated using the complete geometry, where typically not only the silicon chip, but also any high density components close to the chip, such as scattering plates or shielding material is necessary

  18. Development of an algorithm for TLD badge system for dosimetry in the field of X and gamma radiation in terms of Hp(10).

    Science.gov (United States)

    Bakshi, A K; Srivastava, K; Varadharajan, G; Pradhan, A S; Kher, R K

    2007-01-01

    In view of the introduction of International Commission on Radiation Units and Measurements operational quantities Hp(10) and Hp(0.07), defined for individual monitoring, it became necessary to develop an algorithm that gives direct response of the dosemeter in terms of the operational quantities. Hence, for this purpose and also to improve the accuracy in dose estimation especially in the mixed fields of X ray and gamma, an algorithm was developed based on higher-order polynomial fit of the data points generated from the dose-response of discs under different filter regions of the present TL dosemeter system for known delivered doses. Study on the response of the BARC TL dosemeter system based on CaSO(4):Dy Teflon thermoluminescence dosemeter discs in the mixed fields of X and gamma radiation was carried out to ensure that the accuracies are within the prescribed limits recommended by the international organisations. The prevalent algorithm, based on the ratios of the disc response under various filters regions of the dosemeter to pure photons, was tested for different proportion of two radiations in case of mixed field dosimetry. It was found that the accuracy for few fields is beyond the acceptable limit in case of prevalent algorithm. The new proposed algorithm was also tested in mixed fields of photon fields and to pure photon fields of varied angles. It was found that the response of the dosemeter in mixed fields of photons and its angular response are satisfactory. The new algorithm can be used to record and report the personal dose in terms of Hp(10) as per the international recommendation for the present TL dosemeter.

  19. Rigorously testing multialternative decision field theory against random utility models.

    Science.gov (United States)

    Berkowitsch, Nicolas A J; Scheibehenne, Benjamin; Rieskamp, Jörg

    2014-06-01

    Cognitive models of decision making aim to explain the process underlying observed choices. Here, we test a sequential sampling model of decision making, multialternative decision field theory (MDFT; Roe, Busemeyer, & Townsend, 2001), on empirical grounds and compare it against 2 established random utility models of choice: the probit and the logit model. Using a within-subject experimental design, participants in 2 studies repeatedly choose among sets of options (consumer products) described on several attributes. The results of Study 1 showed that all models predicted participants' choices equally well. In Study 2, in which the choice sets were explicitly designed to distinguish the models, MDFT had an advantage in predicting the observed choices. Study 2 further revealed the occurrence of multiple context effects within single participants, indicating an interdependent evaluation of choice options and correlations between different context effects. In sum, the results indicate that sequential sampling models can provide relevant insights into the cognitive process underlying preferential choices and thus can lead to better choice predictions.

  20. [Instrumental radiofrequency electromagnetic radiation dosimetry: general principals and modern methodology].

    Science.gov (United States)

    Perov, S Iu; Kudriashov, Iu B; Rubtsova, N B

    2012-01-01

    The modern experimental radiofrequency electromagnetic field dosimetry approach has been considered. The main principles of specific absorbed rate measurement are analyzed for electromagnetic field biological effect assessment. The general methodology of specific absorbed rate automated dosimetry system applied to establish the compliance of radiation sources with the safety standard requirements (maximum permissible levels and base restrictions) is described.

  1. Path forward for dosimetry cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, P.J. [Sandia National Laboratories, Albuquerque, NM 87185-1146 (United States); Peters, C.D. [Sandia Staffing Alliance, Albuquerque, NM 87110 (United States)

    2011-07-01

    In the 1980's the dosimetry community embraced the need for a high fidelity quantification of uncertainty in nuclear data used for dosimetry applications. This led to the adoption of energy-dependent covariance matrices as the accepted manner of quantifying the uncertainty data. The trend for the dosimetry community to require high fidelity treatment of uncertainty estimates has continued to the current time where requirements on nuclear data are codified in standards such as ASTM E 1018. This paper surveys the current state of the dosimetry cross sections and investigates the quality of the current dosimetry cross section evaluations by examining calculated-to-experimental ratios in neutron benchmark fields. In recent years more nuclear-related technical areas are placing an emphasis on uncertainty quantification. With the availability of model-based cross sections and covariance matrices produced by nuclear data codes, some nuclear-related communities are considering the role these covariance matrices should play. While funding within the dosimetry community for cross section evaluations has been very meager, other areas, such as the solar-related astrophysics community and the US Nuclear Criticality Safety Program, have been supporting research in the area of neutron cross sections. The Cross Section Evaluation Working Group (CSEWG) is responsible for the creation and maintenance of the ENDF/B library which has been the mainstay for the reactor dosimetry community. Given the new trends in cross section evaluations, this paper explores the path forward for the US nuclear reactor dosimetry community and its use of the ENDF/B cross-sections. The major concern is maintenance of the sufficiency and accuracy of the uncertainty estimate when used for dosimetry applications. The two major areas of deficiency in the proposed ENDF/B approach are: 1) the use of unrelated covariance matrices in ENDF/B evaluations and 2) the lack of 'due consideration' of

  2. Testing and linearity calibration of films of phenol compounds exposed to thermal neutron field for EPR dosimetry.

    Science.gov (United States)

    Gallo, S; Panzeca, S; Longo, A; Altieri, S; Bentivoglio, A; Dondi, D; Marconi, R P; Protti, N; Zeffiro, A; Marrale, M

    2015-12-01

    This paper reports the preliminary results obtained by Electron Paramagnetic Resonance (EPR) measurements on films of IRGANOX® 1076 phenols with and without low content (5% by weight) of gadolinium oxide (Gd2O3) exposed in the thermal column of the Triga Mark II reactor of LENA (Laboratorio Energia Nucleare Applicata) of Pavia (Italy). Thanks to their size, the phenolic films here presented are good devices for the dosimetry of beams with high dose gradient and which require accurate knowledge of the precise dose delivered. The dependence of EPR signal as function of neutron dose was investigated in the fluence range between 10(11) cm(-2) and 10(14) cm(-2). Linearity of EPR response was found and the signal was compared with that of commercial alanine films. Our analysis showed that gadolinium oxide (5% by weight) can enhance the thermal neutron sensitivity more than 18 times. Irradiated dosimetric films of phenolic compound exhibited EPR signal fading of about 4% after 10 days from irradiation.

  3. Intercomparisons of neutron dosimeters in support of dosimetry measurements in containment

    Energy Technology Data Exchange (ETDEWEB)

    Auman, L.E.; Miller, W.H. (Univ. of Missouri, Columbia (United States)); Graham, C.C.; Stretch, C.D. (Union Electric Co., Fulton, MO (United States)); Welty, T.J.; West, L. (Univ. of Arkansas, Fayetteville (United States))

    1991-01-01

    In support of neutron dosimetry needs at Union Electric's Callaway nuclear plant, an intercomparison of a variety of neutron detection systems was performed. Eight different neutron detection systems were tested in four different neutron fields, utilizing facilities at the Missouri University research reactor (MURR) and the Southwest Radiation Calibration Center at the University of Arkansas. In general, all results agreed within a factor of 2 in predicting the neutron dose equivalent.

  4. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    Energy Technology Data Exchange (ETDEWEB)

    Rathbone, Bruce A.

    2005-02-25

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. Rev. 0 marks the first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database.

  5. Neutron spectrometry and dosimetry in 100 and 300 MeV quasi-mono-energetic neutron field at RCNP, Osaka University, Japan

    Science.gov (United States)

    Mares, Vladimir; Trinkl, Sebastian; Iwamoto, Yosuke; Masuda, Akihiko; Matsumoto, Tetsuro; Hagiwara, Masayuki; Satoh, Daiki; Yashima, Hiroshi; Shima, Tatsushi; Nakamura, Takashi

    2017-09-01

    This paper describes the results of neutron spectrometry and dosimetry measurements using an extended range Bonner Sphere Spectrometer (ERBSS) with 3He proportional counter performed in quasi-mono-energetic neutron fields at the ring cyclotron facility of the Research Center for Nuclear Physics (RCNP), Osaka University, Japan. Using 100 MeV and 296 MeV proton beams, neutron fields with nominal peak energies of 96 MeV and 293 MeV were generated via 7Li(p,n)7Be reactions. Neutrons produced at 0° and 25° emission angles were extracted into the 100 m long time-of-flight (TOF) tunnel, and the energy spectra were measured at a distance of 35 m from the target. To deduce the corresponding neutron spectra from thermal to the nominal maximum energy, the ERBSS data were unfolded using the MSANDB unfolding code. At high energies, the neutron spectra were also measured by means of the TOF method using NE213 organic liquid scintillators. The results are discussed in terms of ambient dose equivalent, H*(10), and compared with the readings of other instruments operated during the experiment.

  6. Fundamentals of Radiation Dosimetry

    Science.gov (United States)

    Bos, Adrie J. J.

    2011-05-01

    The basic concepts of radiation dosimetry are reviewed on basis of ICRU reports and text books. The radiation field is described with, among others, the particle fluence. Cross sections for indirectly ionizing radiation are defined and indicated is how they are related to the mass energy transfer and mass energy absorption coefficients. Definitions of total and restricted mass stopping powers of directly ionizing radiation are given. The dosimetric quantities, kerma, absorbed dose and exposure together with the relations between them are discussed in depth. Finally it is indicated how the absorbed dose can be measured with a calorimeter by measuring the temperature increase and with an ionisation chamber measuring the charge produced by the ionizing radiation and making use of the Bragg-Gray relation.

  7. Advanced Utility Mercury-Sorbent Field-Testing Program

    Energy Technology Data Exchange (ETDEWEB)

    Ronald Landreth

    2007-12-31

    This report summarizes the work conducted from September 1, 2003 through December 31, 2007 on the project entitled Advanced Utility Mercury-Sorbent Field-Testing Program. The project covers the testing at the Detroit Edison St. Clair Plant and the Duke Power Cliffside and Buck Stations. The St. Clair Plant used a blend of subbituminous and bituminous coal and controlled the particulate emissions by means of a cold-side ESP. The Duke Power Stations used bituminous coals and controlled their particulate emissions by means of hot-side ESPs. The testing at the Detroit Edison St. Clair Plant demonstrated that mercury sorbents could be used to achieve high mercury removal rates with low injection rates at facilities that burn subbituminous coal. A mercury removal rate of 94% was achieved at an injection rate of 3 lb/MMacf over the thirty day long-term test. Prior to this test, it was believed that the mercury in flue gas of this type would be the most difficult to capture. This is not the case. The testing at the two Duke Power Stations proved that carbon- based mercury sorbents can be used to control the mercury emissions from boilers with hot-side ESPs. It was known that plain PACs did not have any mercury capacity at elevated temperatures but that brominated B-PAC did. The mercury removal rate varies with the operation but it appears that mercury removal rates equal to or greater than 50% are achievable in facilities equipped with hot-side ESPs. As part of the program, both sorbent injection equipment and sorbent production equipment was acquired and operated. This equipment performed very well during this program. In addition, mercury instruments were acquired for this program. These instruments worked well in the flue gas at the St. Clair Plant but not as well in the flue gas at the Duke Power Stations. It is believed that the difference in the amount of oxidized mercury, more at Duke Power, was the difference in instrument performance. Much of the equipment was

  8. SU-E-T-399: Evaluation of Selection Criteria for Computational Human Phantoms for Use in Out-Of-Field Organ Dosimetry for Radiotherapy Patients

    Energy Technology Data Exchange (ETDEWEB)

    Pelletier, C; Jung, J [East Carolina University, Greenville, NC (United States); Lee, C [University of Michigan, Ann Arbor, MI (United States); Pyakuryal, A; Lee, C [National Cancer Institute, Rockville, MD (United States); Kim, J [University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

    2015-06-15

    Purpose: To quantify the dosimetric uncertainty due to organ position errors when using height and weight as phantom selection criteria in the UF/NCI Hybrid Phantom Library for the purpose of out-of-field organ dose reconstruction. Methods: Four diagnostic patient CT images were used to create 7-field IMRT plans. For each patient, dose to the liver, right lung, and left lung were calculated using the XVMC Monte Carlo code. These doses were taken to be the ground truth. For each patient, the phantom with the most closely matching height and weight was selected from the body size dependent phantom library. The patient plans were then transferred to the computational phantoms and organ doses were recalculated. Each plan was also run on 4 additional phantoms with reference heights and or weights. Maximum and mean doses for the three organs were computed, and the DVHs were extracted and compared. One sample t-tests were performed to compare the accuracy of the height and weight matched phantoms against the additional phantoms in regards to both maximum and mean dose. Results: For one of the patients, the height and weight matched phantom yielded the most accurate results across all three organs for both maximum and mean doses. For two additional patients, the matched phantom yielded the best match for one organ only. In 13 of the 24 cases, the matched phantom yielded better results than the average of the other four phantoms, though the results were only statistically significant at the .05 level for three cases. Conclusion: Using height and weight matched phantoms does yield better results in regards to out-of-field dosimetry than using average phantoms. Height and weight appear to be moderately good selection criteria, though this selection criteria failed to yield any better results for one patient.

  9. Gel dosimetry for conformal radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G. [Department of Physics of the University and INFN, Milan (Italy)]. e-mail: grazia.gambarini@mi.infn.it

    2005-07-01

    With the continuum development of conformal radio therapies, aimed at delivering high dose to tumor tissue and low dose to the healthy tissue around, the necessities has appeared of suitable improvement of dosimetry techniques giving the possibility of obtaining dose images to be compared with diagnostic images. Also if wide software has been developed for calculating dose distributions in the fields of various radiotherapy units, experimental verifications are necessary, in particular in the case of complex geometries in conformal radiotherapy. Gel dosimetry is a promising method for imaging the absorbed dose in tissue-equivalent phantoms, with the possibility of 3D reconstruction of the spatial dose distribution, with milli metric resolution. Optical imaging of gel dosimeters, based on visible light absorbance analysis, has shown to be a reliable technique for achieving dose distributions. (Author)

  10. Dosimetry service removal

    CERN Multimedia

    Safety Commission

    2010-01-01

    Dear personal dosimeter user, Please note that the Dosimetry service has moved in building 55, the service is now located in the main floor: 55-R-004. Main floor instead of second floor. On your right hand when accessing in the building. Thank you Dosimetry Service

  11. Computational Techniques of Electromagnetic Dosimetry for Humans

    Science.gov (United States)

    Hirata, Akimasa; Fujiwara, Osamu

    There has been increasing public concern about the adverse health effects of human exposure to electromagnetic fields. This paper reviews the rationale of international safety guidelines for human protection against electromagnetic fields. Then, this paper also presents computational techniques to conduct dosimetry in anatomically-based human body models. Computational examples and remaining problems are also described briefly.

  12. EPR Dosimetry - Present and Future

    Energy Technology Data Exchange (ETDEWEB)

    Regulla, D.F. [GSF - National Research Centre for Environment and Health, Institute of Radiation Protection, 85764 Neuherberg (Germany)

    1999-07-01

    In the past, IAEA has played a central role in stipulating research and development in EPR high-dose standardisation as well as in coordinating and organising international dose intercomparison programs, within the Member States of the United Nations from the mid-seventies till today. The future tasks of EPR dosimetry seem to tend towards different subjects such as bio markers, biological radiation effects, post-accident dose reconstruction in the environment, and retrospective human dosimetry. The latter may be considered a promising tool for epidemiology on the way to re-define radiation risk of man for chronicle radiation exposures, based on e.g. South Ural civil population and radiation workers. There are on-going international activities in the field of standardising high-level dosimetry by the American Standards on Testing and Materials (Astm), and by the International Organisation of Standards (ISO). The International Commission on Radiation Units and Measurements (ICRU) is considering the establishment of relevant recommendations concerning industrial radiation processing, but also human dose reconstruction. (Author)

  13. Manipulation of microtubers for direct field utilization in seed production

    NARCIS (Netherlands)

    Pruski, K.; Astatkie, T.; Duplessis, P.; Stewart, L.; Nowak, J.; Struik, P.C.

    2003-01-01

    A two-year field study was conducted to determine the effects of jasmonic acid (JA), light (during in vitro explant production and in vitro tuberization phases), and dormancy-breaking treatment on performance of microtubers in the production of seed tubers (pre-elite) in five potato cultivars. Micro

  14. High-resolution field shaping utilizing a masked multileaf collimator.

    Science.gov (United States)

    Williams, P C; Cooper, P

    2000-08-01

    Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm

  15. Monte Carlo simulations of the electric field close to the body in realistic environments for application in personal radiofrequency dosimetry.

    Science.gov (United States)

    Iskra, S; McKenzie, R; Cosic, I

    2011-11-01

    Personal dosemeters can play an important role in epidemiological studies and in radiofrequency safety programmes. In this study, a Monte Carlo approach is used in conjunction with the finite difference time domain method to obtain distributions of the electric field strength close to a human body model in simulated realistic environments. The field is a proxy for the response of an ideal body-worn electric field dosemeter. A set of eight environments were modelled based on the statistics of Rayleigh, Rice and log-normal fading to simulate outdoor and indoor multipath exposures at 450, 900 and 2100 MHz. Results indicate that a dosemeter mounted randomly within 10-50 mm of the adult or child body model (torso region) will on average underestimate the spatially averaged value of the incident electric field strength by a factor of 0.52 to 0.74 over the frequencies of 450, 900 and 2100 MHz. The uncertainty in results, assessed at the 95 % confidence level (between the 2.5th and 97.5th percentiles) was largest at 2100 MHz and smallest at 450 MHz.

  16. L-alanine detector characterization for dosimetry of small fields in SBRT with VMAT techniques; Caracterizacao do detector de L-alanina para dosimetria de campos pequenos em SBRT com a tecnica de VMAT

    Energy Technology Data Exchange (ETDEWEB)

    Mazaro, Sarah J.; Peres, Leonardo [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil); Baffa, Oswaldo, E-mail: sarahmazaro@yahoo.com.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Departamento de Fisica

    2016-07-01

    New radiotherapy treatment techniques have some problems such as: the dosimetric and geometric of the beam and small fields. Determination of the prescribed dose on the target volume in small fields is hampered due to lack of lateral electronic equilibrium and steep dose gradient along the edges of fields. The choice of radiation better detector becomes important in the dosimetry of small fields. Alanine detector has been shown to be a good choice for measurements of high doses of radiation in small fields. This study aims to characterize the L-alanine detector through the dosimetric tests for SBRT in VMAT techniques. L-alanine response showed a strong linear correlation with the dose (R ² = 0.9865), with significant angles and dose rate dependencies (14%) and (15%) respectively, and minor with the small field size (maximum 4% deviation). (author)

  17. Dosimetry of ionising radiation in modern radiation oncology

    Science.gov (United States)

    Kron, Tomas; Lehmann, Joerg; Greer, Peter B.

    2016-07-01

    Dosimetry of ionising radiation is a well-established and mature branch of physical sciences with many applications in medicine and biology. In particular radiotherapy relies on dosimetry for optimisation of cancer treatment and avoidance of severe toxicity for patients. Several novel developments in radiotherapy have introduced new challenges for dosimetry with small and dynamically changing radiation fields being central to many of these applications such as stereotactic ablative body radiotherapy and intensity modulated radiation therapy. There is also an increasing awareness of low doses given to structures not in the target region and the associated risk of secondary cancer induction. Here accurate dosimetry is important not only for treatment optimisation but also for the generation of data that can inform radiation protection approaches in the future. The article introduces some of the challenges and highlights the interdependence of dosimetric calculations and measurements. Dosimetric concepts are explored in the context of six application fields: reference dosimetry, small fields, low dose out of field, in vivo dosimetry, brachytherapy and auditing of radiotherapy practice. Recent developments of dosimeters that can be used for these purposes are discussed using spatial resolution and number of dimensions for measurement as sorting criteria. While dosimetry is ever evolving to address the needs of advancing applications of radiation in medicine two fundamental issues remain: the accuracy of the measurement from a scientific perspective and the importance to link the measurement to a clinically relevant question. This review aims to provide an update on both of these.

  18. Radiation fields, dosimetry, biokinetics and biophysical models for cancer induction by ionising radiation 1996 - 1999. Mid-term reports for the period 1996-1997

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, P.; Paretzke, H.G.; Roth, P. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz; Michael, B.D. [Mount Vernon Hospital, Northwood (United Kingdom). Gray Lab.; O`Sullivan, D. [Dublin Inst. for Advanced Studies (Ireland)

    1998-12-31

    The main objectives of the first dosimetry project are the measurement of neutron and charged particle flux and energy spectra at altitudes in civil aviation, the determination of response characteristics for detectors, the investigation of calibration procedures, and the evaluation of exposures of aircrews. The overall objective of the second dosimetry project is to improve estimates of dose following the intake of radionuclides by adults and children. The work includes the development of biokinetic and dosimetric models, including models of the gastrointestinal tract, for the systemic behaviour of radionuclides, and for the developing embryo and foetus. Further subjects are target cell dosimetry for short-range particles and the development of computational tools for sensitivity and uncertainty analysis models. The third dosimetry project encompasses the study of different methods for retrospective dose assessments for individuals or groups of individuals accidentally exposed to increased levels of radiation. The methods investigated include electron paramagnetic resonance (EPR) of tooth enamel and chromosome painting (FISH) for lymphocytes in peripheral blood for individual retrospective dose assessments, luminescence techniques on materials in inhabited environment (ceramics, bricks) and model calculations using environmental data as input. (orig.)

  19. The CERN-EU high-energy reference field (CERF) facility for dosimetry at commercial flight altitudes and in space

    CERN Document Server

    Mitaroff, Angela

    2002-01-01

    A reference facility for the calibration and intercomparison of active and passive detectors in broad neutron fields has been available at CERN since 1992. A positively charged hadron beam (a mixture of protons and pions) with momentum of 120 GeV/c hits a copper target, 50 cm thick and 7 cut in diameter. The secondary particles produced in the interaction traverse a shield, at 90 degrees with respect to the direction of the incoming beam, made of either 80 to 160 cm of concrete or 40 cm of iron. Behind the iron shield, the resulting neutron spectrum has a maximum at about 1 MeV, with an additional high-energy component. Behind the 80 cm concrete shield, the neutron spectrum has a second pronounced maximum at about 70 MeV and resembles the high-energy component of the radiation field created by cosmic rays at commercial flight altitudes. This paper describes the facility, reports on the latest neutron spectral measurements, gives an overview of the most important experiments performed by the various collaborat...

  20. The CERN-EU high-energy reference field (CERF) facility for dosimetry at commercial flight altitudes and in space.

    Science.gov (United States)

    Mitaroff, A; Cern, M Silari

    2002-01-01

    A reference facility for the calibration and intercomparison of active and passive detectors in broad neutron fields has been available at CERN since 1992. A positively charged hadron beam (a mixture of protons and pions) with momentum of 120 GeV/c hits a copper target, 50 cm thick and 7 cm in diameter. The secondary particles produced in the interaction traverse a shield, at 90 degrees with respect to the direction of the incoming beam. made of either 80 to 160 cm of concrete or 40 cm of iron. Behind the iron shield, the resulting neutron spectrum has a maximum at about 1 MeV, with an additional high-energy component. Behind the 80 cm concrete shield, the neutron spectrum has a second pronounced maximum at about 70 MeV and resembles the high-energy component of the radiation field created by cosmic rays at commercial flight altitudes. This paper describes the facility, reports on the latest neutron spectral measurements, gives an overview of the most important experiments performed by the various collaborating institutions over recent years and briefly addresses the possible application of the facility to measurements related to the space programme.

  1. Utilization of Near Field Communication Technology for Loyalty Management

    Directory of Open Access Journals (Sweden)

    Ferina Ferdianti

    2013-09-01

    Full Text Available Near Field Communication (NFC is one of wireless technology developed at this time. We can use a mobile phone to do many transactions with NFC. Mobile developments have created to provide convenience for users in all aspects. However, at this time the function of NFC just limited for payment and micropayment. Beside it, there are assets that support to increase sales with attention of loyality management system. In this system, discounts or prizes are given based on data mining for every transaction costumers. Loyalty management has three concept, those are Frequency, Recency and Quantity. The goals are minimizing the cost, making purchase process faster, and managing data obtained through the NFC technology more simple. The result of this paper is the procedure to use data mining of NFC for loyalty management and system design using Unified Modeling Language approach.

  2. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field.

    Science.gov (United States)

    Tee, Sui Seng; DiGialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L; Miloushev, Vesselin; Poot, Alex J; Truong, Steven; Alvarez, Julio A; Aldeborgh, Hannah N; Keshari, Kayvan R

    2016-09-06

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting (13)C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  3. Sampling Hyperpolarized Molecules Utilizing a 1 Tesla Permanent Magnetic Field

    Science.gov (United States)

    Tee, Sui Seng; Digialleonardo, Valentina; Eskandari, Roozbeh; Jeong, Sangmoo; Granlund, Kristin L.; Miloushev, Vesselin; Poot, Alex J.; Truong, Steven; Alvarez, Julio A.; Aldeborgh, Hannah N.; Keshari, Kayvan R.

    2016-09-01

    Hyperpolarized magnetic resonance spectroscopy (HP MRS) using dynamic nuclear polarization (DNP) is a technique that has greatly enhanced the sensitivity of detecting 13C nuclei. However, the HP MRS polarization decays in the liquid state according to the spin-lattice relaxation time (T1) of the nucleus. Sampling of the signal also destroys polarization, resulting in a limited temporal ability to observe biologically interesting reactions. In this study, we demonstrate that sampling hyperpolarized signals using a permanent magnet at 1 Tesla (1T) is a simple and cost-effective method to increase T1s without sacrificing signal-to-noise. Biologically-relevant information may be obtained with a permanent magnet using enzyme solutions and in whole cells. Of significance, our findings indicate that changes in pyruvate metabolism can also be quantified in a xenograft model at this field strength.

  4. Development of polyaniline thin films for gamma radiation dosimetry; Desenvolvimento de filmes finos de polianilina para dosimetria da radiacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Ana Paula; Araujo, Elmo S. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear; Azevedo, Walter M. de [Pernambuco Univ., Recife, PE (Brazil). Dept. de Quimica Fundamental

    2001-07-01

    The increasing applications of the ionizing radiation added to the difficulty on operation of some dosimeters have became necessary the development of news materials and news dosimetry techniques. On the other hand, the study of the properties of conducts polymers are quite recent as well as its research in the dosimetry field is still superficial. The utilization of polyaniline (PANI) as a dosimetric material is of great relevancy, because this polymer has got good quality in the dosimetry. It is easy to operation, the devices may be fabricated in different geometry, it is a low cost material, and the electrical properties variation measurement system is simple. In addition, it does not exist previously study that characterizes this polymer as a dosimeter. Some early results have showed that doped PANI when irradiated with gamma rays ({sup 60} Co), dose range from 0 to 10kGy, responds proportionally to the doses above 1kGy. Thus, it is possible the utilization this polymer in high-energy dosimetry. Studies much more detailed are being made in order to complete the evidence of PANI as a dosimetric material. (author)

  5. Methodology for Mixed Field Inhalation Dosimetry in Monazite Areas using a Twin-Cup Dosemeter with Three Track Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Mayya, Y.S.; Eappen, K.P.; Nambi, K.S.V

    1998-07-01

    A methodology is proposed for estimating the gas and potential alpha energy concentrations (PAECs), and inhalation dose rates due to a mixed field of radon, thoron and their progeny present in the indoor atmosphere, using a radon-thoron discriminating dosemeter having three solid state nuclear track detectors (SSNTDs). The gas concentrations present in the vicinity of the dosemeter are directly measured through SSNTDs exposed in the 'cup mode'. The bare track density rates are related to the gas and the progeny concentrations by incorporating ventilation rate dependent spatial profiles for thoron gas. The ventilation rate is extracted as a real positive root of the governing equation and from this, the PAECs as well as the inhalation dose rates are estimated through the use of standard formulae. Error estimates on the dose rates have been carried out. Analyses of the field data from a sample survey of 35 houses situated in monazite bearing high background radiation areas of Kerala indicate that the methodology works successfully in a majority of the cases. Results for 22 cases which showed less than 100% statistical error are presented. These show median values of about 4.8 Bq.m{sup -3} and 462 Bq.m{sup -3} for radon and room averaged thoron concentrations, 0.5 mWL and 129 mWL for radon progeny and thoron progeny PAECs, and 1.21 {mu}Sv.h{sup -1} for inhalation dose rate. Although a complete picture would emerge only at the end of the ongoing large scale survey, the sample survey already indicates that indoor thoron levels in the Kerala monazite area are the highest reported so far in the literature. (author)

  6. Dosimetry of Low-Energy Beta Radiation

    DEFF Research Database (Denmark)

    Borg, Jette

    Useful techniques and procedures for derermination of absorbed doses from exposure in a low-energy beta radiation were studied and evaluated. The four techniques included were beta spectrometry, extrapolation chamber dosimetry, Monte Carlo (MC) calculations, and exoelectron dosimetry. As a typical...... low-energy beta radiation field a moderated spectrum from a carbon-14 source was used. The measured responce of a Si(Li) detector to photons (bremsstrahlung) showed fine agreemant with the MC calculated photon response, whereas the difference between measured and MC calculated response to electrons...

  7. Dosimetry of Low-Energy Beta Radiation

    DEFF Research Database (Denmark)

    Borg, Jette

    Useful techniques and procedures for derermination of absorbed doses from exposure in a low-energy beta radiation were studied and evaluated. The four techniques included were beta spectrometry, extrapolation chamber dosimetry, Monte Carlo (MC) calculations, and exoelectron dosimetry. As a typical...... low-energy beta radiation field a moderated spectrum from a carbon-14 source was used. The measured responce of a Si(Li) detector to photons (bremsstrahlung) showed fine agreemant with the MC calculated photon response, whereas the difference between measured and MC calculated response to electrons...

  8. Neutron dosimetry for low dose rate Cf-252 AT sources and adherence to recent clinical dosimetry protocol for brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Rivard, M.J.; Wierzbicki, J.G.; Van den Heuvel, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Radiation Oncology; Martin, R.C. [Oak Ridge National Lab., TN (United States). Chemical Technology Div.

    1997-12-01

    In 1995, the American Association of Physicists in Medicine Task Group 43 (AAPM TG-43) published a protocol obsoleting all mixed-field radiation dosimetry for Cf-252. Recommendations for a new brachytherapy dosimetry formalism made by this Task Group favor quantification of source strength in terms of air kerma rather than apparent Curies or other radiation units. Additionally, representation of this dosimetry data in terms of radial dose functions, anisotropy functions, geometric factors, and dose rate constants are in an angular and radial (spherical) coordinate system as recommended, rather than the along-away dosimetry data (Cartesian coordinate system) currently available. This paper presents the initial results of calculated neutron dosimetry in a water phantom for a Cf-252 applicator tube (AT) type medical source soon available from Oak Ridge National Laboratory (ORNL).

  9. Muskrat population dynamics and vegetation utilization : A management plan : Report on 1980 field season

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report for the 1980 field season on a study of muskrat population dynamics and vegetation utilization, being led by Utah State University for a doctorate...

  10. Multi-spectral wide-field imaging for PplX PDT dosimetry of skin (Conference Presentation)

    Science.gov (United States)

    LaRochelle, Ethan; Chun, Hayden H.; Hasan, Tayyaba; Pogue, Brian W.; Maytin, Edward V.; Chapman, Michael S.; Davis, Scott C.

    2016-03-01

    Actinic Kertoses (AK) are common pre-cancerous lesions associated with sun-damaged skin. While generally benign, the condition can progress to squamous cell carcinoma (SCC) and is a particular concern for immunosuppressed patients who are susceptible to uncontrolled AK and SCC. Among the FDA-approved treatment options for AK, ALA-based photodynamic therapy is unique in that it is non-scarring and can be repeated on the same area. However, response rates vary widely due to variations in drug and light delivery, PpIX production, and tissue oxygenation. Thus, developing modalities to predict response is critical to enable patient-specific treatment-enhancing interventions. To that end, we have developed a wide-field spectrally-resolved fluorescence imaging system capable of red and blue light excitation. While blue light excites PpIX efficiently, poor photon penetration limits the image content to superficial layers of skin. Red light excitation, on the other hand, can reveal fluorescence information originating from deeper in tissue, which may provide relevant information about PpIX distribution. Our instrument illuminates the skin via a fiber-based ring illuminator, into which is coupled sequentially a white light source, and blue and red laser diodes. Light emitted from the tissue passes through a high-speed filter wheel with filters selected to resolve the PpIX emission spectrum. This configuration enables the use of spectral fitting to decouple PpIX fluorescence from background signal, improving sensitivity to low concentrations of PpIX. Images of tissue-simulating phantoms and animal models confirm a linear response to PpIX, and the ability to image sub-surface PpIX inaccessible with blue light using red excitation.

  11. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    Energy Technology Data Exchange (ETDEWEB)

    Rathbone, Bruce A.

    2009-08-28

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program (HEDP) which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee (HPDAC) which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document.

  12. Design and experimental testing of air slab caps which convert commercial electron diodes into dual purpose, correction-free diodes for small field dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Charles, P. H., E-mail: paulcharles111@gmail.com [Department of Radiation Oncology, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Brisbane, Queensland 4102, Australia and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Cranmer-Sargison, G. [Department of Medical Physics, Saskatchewan Cancer Agency, 20 Campus Drive, Saskatoon, Saskatchewan S7L 3P6, Canada and College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan S7N 5E5 (Canada); Thwaites, D. I. [Institute of Medical Physics, School of Physics, University of Sydney, New South Wales 2006 (Australia); Kairn, T. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia and Genesis CancerCare Queensland, The Wesley Medical Centre, Suite 1, 40 Chasely Street, Auchenflower, Brisbane, Queensland 4066 (Australia); Crowe, S. B.; Langton, C. M.; Trapp, J. V. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Pedrazzini, G. [Genesis CancerCare Queensland, The Wesley Medical Centre, Suite 1, 40 Chasely Street, Auchenflower, Brisbane, Queensland 4066 (Australia); Aland, T.; Kenny, J. [Epworth Radiation Oncology, 89 Bridge Road, Richmond, Melbourne, Victoria 3121 (Australia)

    2014-10-15

    Purpose: Two diodes which do not require correction factors for small field relative output measurements are designed and validated using experimental methodology. This was achieved by adding an air layer above the active volume of the diode detectors, which canceled out the increase in response of the diodes in small fields relative to standard field sizes. Methods: Due to the increased density of silicon and other components within a diode, additional electrons are created. In very small fields, a very small air gap acts as an effective filter of electrons with a high angle of incidence. The aim was to design a diode that balanced these perturbations to give a response similar to a water-only geometry. Three thicknesses of air were placed at the proximal end of a PTW 60017 electron diode (PTWe) using an adjustable “air cap”. A set of output ratios (OR{sub Det}{sup f{sub c}{sub l}{sub i}{sub n}}) for square field sizes of side length down to 5 mm was measured using each air thickness and compared to OR{sub Det}{sup f{sub c}{sub l}{sub i}{sub n}} measured using an IBA stereotactic field diode (SFD). k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} was transferred from the SFD to the PTWe diode and plotted as a function of air gap thickness for each field size. This enabled the optimal air gap thickness to be obtained by observing which thickness of air was required such that k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} was equal to 1.00 at all field sizes. A similar procedure was used to find the optimal air thickness required to make a modified Sun Nuclear EDGE detector (EDGEe) which is “correction-free” in small field relative dosimetry. In addition, the feasibility of experimentally transferring k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r

  13. Neutron-photon mixed field dosimetry by TLD-700 glow curve analysis and its implementation in dose monitoring for Boron Neutron Capture Therapy (BNCT) treatments

    Energy Technology Data Exchange (ETDEWEB)

    Boggio, E. F.; Longhino, J. M. [Centro Atomico Bariloche, Departamento de Fisica de Reactores y Radiaciones / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina); Andres, P. A., E-mail: efboggio@cab.cnea.gov.ar [Centro Atomico Bariloche, Division Proteccion Radiologica / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina)

    2015-10-15

    BNCT is a cancerous cells selective, non-conventional radiotherapy modality to treat malignant tumors such as glioblastoma, melanoma and recurrent head and neck cancer. It consists of a two-step procedure: first, the patient is injected with a tumor localizing drug containing a non-radioactive isotope (Boron-10) with high slow neutron capture cross-section. In a second step, the patient is irradiated with neutrons, which are absorbed by the Boron-10 agent with the subsequently nuclear reaction B- 10(n,a)Li-7, thereby resulting in dose at cellular level due to the high-Let particles. The neutron fields suitable for BNCT are characterized by high neutron fluxes and low gamma dose. Determination of each component is not an easy task, especially when the volume of measurement is quite small or inaccessible for a miniature ionization chamber, for example. A method of measuring the photon and slow neutron dose(mainly by N-14 and B-10) from the glow curve (GC) analysis of a single {sup 7}LiF thermoluminescence detector is evaluated. This method was suggested by the group headed by Dr. Grazia Gambarini. The dosemeters used were TLD-600 ({sup 6}LiF:Mg,Ti with 95.6% {sup 6}Li) and TLD-700 ({sup 7}LiF:Mg,Ti with 99.9% {sup 7}LiF) from Harshaw. Photon dose measurement using the GC analysis method with TLD-700 in mixed fields requires the relation of the two main peaks of a TLD-600 GC shape obtained from an exposition to the same neutron field, and a photon calibrated GC with TLD-700. The requirements for slow neutron dose measurements are similar. In order to properly apply the GC analysis method at the Ra-6 Research Reactor BNCT facility, measurements were carried out in a standard water phantom, fully characterized on the BNCT beam by conventional techniques (activation detectors and paired ionization chambers technique). Next, the method was implemented in whole body dose monitoring of a patient undergoing a BNCT treatment, using a Bo MAb (Bottle Manikin Absorption) phantom

  14. Reactor Dosimetry State of the Art 2008

    Science.gov (United States)

    Voorbraak, Wim; Debarberis, Luigi; D'Hondt, Pierre; Wagemans, Jan

    2009-08-01

    . Williams, A. P. Ribaric and T. Schnauber. Agile high-fidelity MCNP model development techniques for rapid mechanical design iteration / J. A. Kulesza.Extension of Raptor-M3G to r-8-z geometry for use in reactor dosimetry applications / M. A. Hunter, G. Longoni and S. L. Anderson. In vessel exposure distributions evaluated with MCNP5 for Atucha II / J. M. Longhino, H. Blaumann and G. Zamonsky. Atucha I nuclear power plant azimutal ex-vessel flux profile evaluation / J. M. Longhino ... [et al.]. UFTR thermal column characterization and redesign for maximized thermal flux / C. Polit and A. Haghighat. Activation counter using liquid light-guide for dosimetry of neutron burst / M. Hayashi ... [et al.]. Control rod reactivity curves for the annular core research reactor / K. R. DePriest ... [et al.]. Specification of irradiation conditions in VVER-440 surveillance positions / V. Kochkin ... [et al.]. Simulations of Mg-Ar ionisation and TE-TE ionisation chambers with MCNPX in a straightforward gamma and beta irradiation field / S. Nievaart ... [et al.]. The change of austenitic stainless steel elements content in the inner parts of VVER-440 reactor during operation / V. Smutný, J. Hep and P. Novosad. Fast neutron environmental spectrometry using disk activation / G. Lövestam ... [et al.]. Optimization of the neutron activation detector location scheme for VVER-lOOO ex-vessel dosimetry / V. N. Bukanov ... [et al.]. Irradiation conditions for surveillance specimens located into plane containers installed in the WWER-lOOO reactor of unit 2 of the South-Ukrainian NPP / O. V. Grytsenko. V. N. Bukanov and S. M. Pugach. Conformity between LRO mock-ups and VVERS NPP RPV neutron flux attenuation / S. Belousov. Kr. Ilieva and D. Kirilova. FLUOLE: a new relevant experiment for PWR pressure vessel surveillance / D. Beretz ... [et al.]. Transport of neutrons and photons through the iron and water layers / M. J. Kost'ál ... [et al.]. Condition evaluation of spent nuclear fuel assemblies

  15. INDIVIDUAL DOSIMETRY SERVICE

    CERN Multimedia

    2000-01-01

    Personnel in the distribution groups Aleph, Delphi, L3, Opal who also work for other experiments than at LEP, should contact their dispatchers to explain their activities for the future, after LEP dismantling in order to be maintained on the regular distribution list at Individual DosimetryWe inform all staff and users under regular dosimetric control that the dosimeters for the monitoring period MAY/JUNE will be available from their usual dispatchers on Tuesday 2 May.Please have your films changed before the 12 May.The colour of the dosimeter valid in is MAY/JUNE is YELLOW.Individual Dosimetry Service will be closed on Friday 28 April.

  16. Nuclear medicine radiation dosimetry

    CERN Document Server

    McParland, Brian J

    2010-01-01

    Complexities of the requirements for accurate radiation dosimetry evaluation in both diagnostic and therapeutic nuclear medicine (including PET) have grown over the past decade. This is due primarily to four factors: growing consideration of accurate patient-specific treatment planning for radionuclide therapy as a means of improving the therapeutic benefit, development of more realistic anthropomorphic phantoms and their use in estimating radiation transport and dosimetry in patients, design and use of advanced Monte Carlo algorithms in calculating the above-mentioned radiation transport and

  17. Dosimetry of infant exposure to power-frequency magnetic fields: variation of 99th percentile induced electric field value by posture and skin-to-skin contact.

    Science.gov (United States)

    Li, Congsheng; Wu, Tongning

    2015-04-01

    Infant exposure to 50 Hz magnetic fields from power lines was numerically analyzed in this study. Dosimetric variability due to posture and skin-to-skin contact was evaluated using human anatomical models including a recently developed model of a 12-months-old infant. As proposed by the International Commission on Non-Ionizing Radiation Protection, the induced E-field strength (99th percentile value, E99 ) for the central nerve systems (E99_CNS ) and peripheral nerve system (E99_PNS ), were used as metrics. Results showed that the single (free of contact with others) infant model has lower E99 (E99_CNS and E99_PNS inclusive) compared with single adult and child models when exposed to the same power-frequency magnetic field. Also, studied postures of sitting, standing, or arm-up, would not change E99 _PNS . However, skin-to-skin contact with other models could significantly raise induced E-field strength in the infant (e.g., contact on 0.93% of the infant's total surface increased E99_PNS by 213%). Simulations with canonical models were conducted to assess different factors contributing to the E99 enhancement. Results indicated the importance of thoroughly investigating the conservativeness of current safety guidelines in the case of skin-to-skin contact, especially with infants.

  18. Dosimetry Comparison between Volumetric Modulated Arc Therapy with RapidArc and Fixed Field Dynamic IMRT for Local-Regionally Advanced Nasopharyngeal Carcinoma

    Institute of Scientific and Technical Information of China (English)

    Bao-min Zheng; Xiao-xia Dong; Hao Wu; You-jia Duan; Shu-kui Han; Yan Sun

    2011-01-01

    Objective:A dosimetric study was performed to evaluate the performance of volumetric modulated arc radiotherapy with RapidArc on locally advanced nasopharyngeal carcinoma (NPC).Methods:The CT scan data sets of 20 patients of locally advanced NPC were selected randomly.The plans were managed using volumetric modulated arc with RapidArc and fixed nine-field coplanar dynamic intensity-modulated radiotherapy (IMRT) for these patients.The dosimetry of the planning target volumes (PTV),the organs at risk (OARs) and the healthy tissue were evaluated.The dose prescription was set to 70 Gy to the primary tumor and 60 Gy to the clinical target volumes (CTV) in 33 fractions.Each fraction applied daily,five fractions per week.The monitor unit (MU) values and the delivery time were scored to evaluate the expected treatment efficiency.Results:Both techniques had reached clinical treatment's requirement.The mean dose (Dmean),maximum dose (Dmax) and minimum dose (Dmin) in RapidArc and fixed field IMRT for PTV were 68.4±0.6 Gy,74.8±0.9 Gy and 56.8±1.1 Gy; and 67.6±0.6 Gy,73.8±0.4 Gy and 57.5±0.6 Gy (P<0.05),respectively.Homogeneity index was 78.85±1.29 in RapidArc and 80.34±0.54 (P<0.05) in IMRT.The conformity index (CI:95%) was 0.78±0.01 for both techniques (P>0.05).Compared to IMRT,RapidArc allowed a reduction of Dmean to the brain stem,mandible and optic nerves of 14.1% (P<0.05),5.6% (P<0.05) and 12.2% (P<0.05),respectively.For the healthy tissue and the whole absorbed dose,Dmean of RapidArc was reduced by 3.6% (P<0.05),and 3.7% (P<0.05),respectively.The Dmean to the parotids,the spinal cord and the lens had no statistical difference among them.The mean MU values of RapidArc and IMRT were 550 and 1,379.The mean treatment time of RapidArc and IMRT was 165 s and 447 s.Compared to IMRT,the delivery time and the MU values of RapidArc were reduced by 63% and 60%,respectively.Conclusion:For locally advanced NPC,both RapidArc and IMRT reached

  19. Dosimetry for SIRT; Dosimetrie bei der SIRT

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, S.P. [Universitatesklinikum Essen (Germany). Klinik fuer Nuklearmedizin

    2011-09-15

    Dosimetry is only one aspect of treatment planning for 'Selective internal radiotherapy' (SIRT) or 'transarterial radioembolization' (TARE) with Yttrium-90 Microspheres is an emerging palliative therapy for malignant hepatoma. Dosimetric considerations, together with interventional, oncological and hepatological aspects need to be considered for optimal treatment stratification. The product-specific dosimetric calculations for 2 commercially available microsphere products are compared and set in relation to the average doses to liver and tumor. Ostensible discrepancies between the dose-response of Y-90-microspheres and external beam radiation therapy are discussed in the context of radiobiological concepts. (orig.)

  20. High frequency electromagnetic dosimetry

    CERN Document Server

    Sánchez-Hernández, David A

    2009-01-01

    Along with the growth of RF and microwave technology applications, there is a mounting concern about the possible adverse effects over human health from electromagnetic radiation. Addressing this issue and putting it into perspective, this groundbreaking resource provides critical details on the latest advances in high frequency electromagnetic dosimetry.

  1. Individual dosimetry service

    CERN Document Server

    2004-01-01

    We inform all staff and users under regular dosimetry control that the dosimeters for the monitoring period JULY-AUGUST 2004 are available from their usual dispatchers. Please have your films changed before the 15 JULY 2004. The color of the dosimeter valid in July-August 2004 is PINK.

  2. Dosimetry characteristics of multi-leaf collimator field for TrueBeam%TrueBeam加速器多叶准直器射野剂量学特性

    Institute of Scientific and Technical Information of China (English)

    熊绮丽; 石勇; 徐刚; 顾强

    2015-01-01

    医用电子直线加速器未均整射束的剂量学特征和优势早已被证明,但是随着三维适形和调强放射治疗技术的发展,临床治疗的射野(Field)主要是由多叶准直器射野形成,而有关未均整射束的多叶准直器射野剂量特征的研究很少。本文研究TrueBeam加速器6 MV-X未均整射束的多叶准直器射野剂量特征。利用蒙特卡罗(Monte Carlo, MC)模拟和三维剂量扫描系统临床测量,对比和分析射野离轴比曲线剂量特征。结果表明:蒙特卡罗模拟和临床测量未均整射束下多叶准直器叶片到位精度、X和Y方向的漏射量、射野半影、叶片间凹凸结构对射野剂量的影响大体一致。多叶准直器形成不规则射野的几何学、蒙特卡罗模拟和临床测量的不符合度(MC 或临床测量50%等剂量曲线的面积与射野几何面积的差值相对于射野实际面积的百分数)分别为3.629%、3.2626%和2.0394%。圆形射野、具有凹凸边界射野几何学和蒙特卡罗模拟的不符合度分别为0.8662%、0.8794%和0.2314%、0.8170%。为未均整射束条件下多叶准直器的临床合理使用提供可靠的依据。%Background: The dose distribution of the Flatting-Filter-Free (FFF) of medical linear accelerator (LINACS) has been proved to have its advantages in clinical use. With the recent development of three-dimensional conformal radiotherapy and intensity-modulated radiation therapy, field of clinical treatment is mainly achieved by using Multi-leaf Collimator (MLC). Because of the rare researches on dosimetry characteristics of MLC field under FFF beam, it is interesting to note the importance of its further development.Purpose:For the TureBeam accelerator of 6 MV-X, the dose characteristics of the MLC are studied in the presence of the FFF beam.Methods:The off-axis dose curve characteristics are analyzed by using the Monte Carlo (MC) method, combined with three-dimensional dose scanning data

  3. EPID dosimetry for pretreatment quality assurance with two commercial systems.

    Science.gov (United States)

    Bailey, Daniel W; Kumaraswamy, Lalith; Bakhtiari, Mohammad; Malhotra, Harish K; Podgorsak, Matthew B

    2012-07-05

    This study compares the EPID dosimetry algorithms of two commercial systems for pretreatment QA, and analyzes dosimetric measurements made with each system alongside the results obtained with a standard diode array. 126 IMRT fields are examined with both EPID dosimetry systems (EPIDose by Sun Nuclear Corporation, Melbourne FL, and Portal Dosimetry by Varian Medical Systems, Palo Alto CA) and the diode array, MapCHECK (also by Sun Nuclear Corporation). Twenty-six VMAT arcs of varying modulation complexity are examined with the EPIDose and MapCHECK systems. Optimization and commissioning testing of the EPIDose physics model is detailed. Each EPID IMRT QA system is tested for sensitivity to critical TPS beam model errors. Absolute dose gamma evaluation (3%, 3 mm, 10% threshold, global normalization to the maximum measured dose) yields similar results (within 1%-2%) for all three dosimetry modalities, except in the case of off-axis breast tangents. For these off-axis fields, the Portal Dosimetry system does not adequately model EPID response, though a previously-published correction algorithm improves performance. Both MapCHECK and EPIDose are found to yield good results for VMAT QA, though limitations are discussed. Both the Portal Dosimetry and EPIDose algorithms, though distinctly different, yield similar results for the majority of clinical IMRT cases, in close agreement with a standard diode array. Portal dose image prediction may overlook errors in beam modeling beyond the calculation of the actual fluence, while MapCHECK and EPIDose include verification of the dose calculation algorithm, albeit in simplified phantom conditions (and with limited data density in the case of the MapCHECK detector). Unlike the commercial Portal Dosimetry package, the EPIDose algorithm (when sufficiently optimized) allows accurate analysis of EPID response for off-axis, asymmetric fields, and for orthogonal VMAT QA. Other forms of QA are necessary to supplement the limitations of the

  4. Neutron spectrometry and dosimetry with ANNs

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Hernandez D, V. M. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Departamento de Ingenieria Nuclear, Universidad Politecnica de Madrid, Jose Gutierrez Abascal 2, 28006 Madrid (Spain)], e-mail: fermineutron@yahoo.com

    2009-10-15

    Artificial neural networks technology has been applied to unfold the neutron spectra and to calculate the effective dose, the ambient equivalent dose, and the personal dose equivalent for {sup 252}Cf and {sup 241}AmBe neutron sources. A Bonner sphere spectrometry with a {sup 6}LiI(Eu) scintillator was utilized to measure the count rates of the spheres that were utilized as input in two artificial neural networks, one for spectrometry and another for dosimetry. Spectra and the ambient dose equivalent were also obtained with BUNKIUT code and the UTA4 response matrix. With both procedures spectra and ambient dose equivalent agrees in less than 10%. (author)

  5. Criticality accident dosimetry with ESR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    D`Errico, F. [DCMN, Universita degli Studi di Pisa (Italy); Fattibene, P.; Onori, S.; Pantaloni, M. [Istituto Superiore di Sanita, Rome (Italy). Lab. di Fisica

    1997-01-01

    The suitability of the ESR alanine and sugar detectors for criticality accident dosimetry was experimentally investigated during an intercomparison of dosimetry techniques. Tests were performed irradiating detectors both free-in-air and on-phantom during controlled criticality excursions at the SILENE reactor in Valduc, France. Several grays of absorbed dose were imparted in neutron gamma-ray fields of various relative intensities and spectral distributions. Analysed results confirmed the potential of these systems which can immediately provide an acute dose assessment with an average underestimate of 30% in the various fields. This performance allows for the screening of severely exposed individuals and meets the IAEA recommendations on the early estimate of accident absorbed doses. (Author).

  6. The dosimetry of ionizing radiation

    CERN Document Server

    1990-01-01

    A continuation of the treatise The Dosimetry of Ionizing Radiation, Volume III builds upon the foundations of Volumes I and II and the tradition of the preceeding treatise Radiation Dosimetry. Volume III contains three comprehensive chapters on the applications of radiation dosimetry in particular research and medical settings, a chapter on unique and useful detectors, and two chapters on Monte Carlo techniques and their applications.

  7. About the parametrizations utilized to perform magnetic moments measurements using the transient field technique

    Science.gov (United States)

    Gómez, A. M.; Torres, D. A.

    2016-07-01

    The experimental study of nuclear magnetic moments, using the Transient Field technique, makes use of spin-orbit hyperfine interactions to generate strong magnetic fields, above the kilo-Tesla regime, capable to create a precession of the nuclear spin. A theoretical description of such magnetic fields is still under theoretical research, and the use of parametrizations is still a common way to address the lack of theoretical information. In this contribution, a review of the main parametrizations utilized in the measurements of Nuclear Magnetic Moments will be presented, the challenges to create a theoretical description from first principles will be discussed.

  8. Quantitative imaging for clinical dosimetry

    Science.gov (United States)

    Bardiès, Manuel; Flux, Glenn; Lassmann, Michael; Monsieurs, Myriam; Savolainen, Sauli; Strand, Sven-Erik

    2006-12-01

    Patient-specific dosimetry in nuclear medicine is now a legal requirement in many countries throughout the EU for targeted radionuclide therapy (TRT) applications. In order to achieve that goal, an increased level of accuracy in dosimetry procedures is needed. Current research in nuclear medicine dosimetry should not only aim at developing new methods to assess the delivered radiation absorbed dose at the patient level, but also to ensure that the proposed methods can be put into practice in a sufficient number of institutions. A unified dosimetry methodology is required for making clinical outcome comparisons possible.

  9. Neutron beam measurement dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Amaro, C.R. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-11-01

    This report describes animal dosimetry studies and phantom measurements. During 1994, 12 dogs were irradiated at BMRR as part of a 4 fraction dose tolerance study. The animals were first infused with BSH and irradiated daily for 4 consecutive days. BNL irradiated 2 beagles as part of their dose tolerance study using BPA fructose. In addition, a dog at WSU was irradiated at BMRR after an infusion of BPA fructose. During 1994, the INEL BNCT dosimetry team measured neutron flux and gamma dose profiles in two phantoms exposed to the epithermal neutron beam at the BMRR. These measurements were performed as a preparatory step to the commencement of human clinical trials in progress at the BMRR.

  10. Phantom positioning variation in the Gamma Knife® Perfexion dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Nathalia Almeida; Potiens, Maria da Penha Albuquerque [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Saraiva, Crystian [Hospital do Coracao, Sao Paulo, SP (Brazil)

    2015-07-01

    The use of small volume ionization chamber has become required for the dosimetry of equipment that use small radiation fields. A pinpoint ionization chamber is ideal for the dosimetry of a Gamma Knife® Perfexion (GKP) unit. In this work, this chamber was inserted into the phantom, and measurements were performed with the phantom in different positions, in order to verify if the change in the phantom positioning affects the dosimetry of the GKP. Three different phantom positions were performed. The variation in the result is within the range allowed for the dosimetry of a GKP equipment. (author)

  11. INDIVIDUAL DOSIMETRY SERVICE

    CERN Multimedia

    2000-01-01

    Personnel in the distribution groups Aleph, Delphi, L3, Opal who also work for other experiments than at LEP, should contact the Individual Dosimetry Service.We inform all staff and users under regular dosimetric control that the dosimeters for the monitoring period MARCH/APRIL will be available from their usual dispatchers on the third of March 2000.Please have your films changed before the 13th of March.The colour of the dosimeter valid in MARCH/APRIL is BLUE.

  12. INDIVIDUAL DOSIMETRY SERVICE

    CERN Multimedia

    1999-01-01

    Personnel in the distribution groups Aleph, Delphi, L3, Opal who also work for other experiments than at LEP, should contact the Individual Dosimetry ServiceWe inform all staff and users under regular dosimetric control that the dosimeters for the monitoring period JANUARY/FEBRUARY will be available from their usual dispatchers on Monday the third of January 2000.Please have your films changed:before the 12 January.The colour of the dosimeter valid in JANUARY/FEBRUARY is WHITE.

  13. Dosimetry: an ARDENT topic

    CERN Multimedia

    CERN Bulletin

    2012-01-01

    The first annual ARDENT workshop took place in Vienna from 20 to 23 November. The workshop gathered together the Early-Stage Researchers (ESR) and their supervisors, plus other people involved from all the participating institutions.   “The meeting, which was organised with the local support of the Austrian Institute of Technology, was a nice opportunity for the ESRs to get together, meet each other, and present their research plans and some preliminary results of their work,” says Marco Silari, a member of CERN Radiation Protection Group and the scientist in charge of the programme. Two full days were devoted to a training course on radiation dosimetry, delivered by renowned experts. The workshop closed with a half-day visit to the MedAustron facility in Wiener Neustadt. ARDENT (Advanced Radiation Dosimetry European Network Training) is a Marie Curie ITN project funded under EU FP7 with €4 million. The project focuses on radiation dosimetry exploiting se...

  14. Applied physics of external radiation exposure dosimetry and radiation protection

    CERN Document Server

    Antoni, Rodolphe

    2017-01-01

    This book describes the interaction of living matter with photons, neutrons, charged particles, electrons and ions. The authors are specialists in the field of radiation protection. The book synthesizes many years of experiments with external radiation exposure in the fields of dosimetry and radiation shielding in medical, industrial and research fields. It presents the basic physical concepts including dosimetry and offers a number of tools to be used by students, engineers and technicians to assess the radiological risk and the means to avoid them by calculating the appropriate shields. The theory of radiation interaction in matter is presented together with empirical formulas and abacus. Numerous numerical applications are treated to illustrate the different topics. The state of the art in radiation protection and dosimetry is presented in detail, especially in the field of simulation codes for external exposure to radiation, medical projects and advanced research. Moreover, important data spread in differ...

  15. Radiation protection dosimetry in medicine - Report of the working group n.9 of the European radiation dosimetry group (EURADOS) - coordinated network for radiation dosimetry (CONRAD - contract EC N) fp6-12684; Dosimetrie pour la radioprotection en milieu medical - rapport du groupe de travail n. 9 du European radiation dosimetry group (EURADOS) - coordinated netword for radiation dosimetry (CONRAD - contrat CE fp6-12684)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This report present the results achieved within the frame of the work the WP 7 (Radiation Protection Dosimetry of Medical Staff) of the coordination action CONRAD (Coordinated Network for Radiation Dosimetry) funded through the 6. EU Framework Program. This action was coordinated by EURADOS (European Radiation Dosimetry Group). EURADOS is an organization founded in 1981 to advance the scientific understanding and the technical development of the dosimetry of ionising radiation in the fields of radiation protection, radiobiology, radiation therapy and medical diagnosis by promoting collaboration between European laboratories. WP7 coordinates and promotes European research for the assessment of occupational exposures to staff in therapeutic and diagnostic radiology workplaces. Research is coordinated through sub-groups covering three specific areas: 1. Extremity dosimetry in nuclear medicine and interventional radiology: this sub-group coordinates investigations in the specific fields of the hospitals and studies of doses to different parts of the hands, arms, legs and feet; 2. Practice of double dosimetry: this sub-group reviews and evaluates the different methods and algorithms for the use of dosemeters placed above and below lead aprons in large exposure during interventional radiology procedures, especially to determine effective doses to cardiologists during cardiac catheterization; and 3. Use of electronic personal dosemeters in interventional radiology: this sub-group coordinates investigations in laboratories and hospitals, and intercomparisons with passive dosemeters with the aim to enable the formulation of standards. (authors)

  16. Neutron dosimetry: problems, solutions, prospects and the role of trace detectors; Dosimetria neutronica: problemas, soluciones, perspectivas y el papel de los detectores de traza

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, F. [Consejo de Seguridad Nuclear, Justo Dorado 11, 28040 Madrid (Spain)

    2009-10-15

    It is present in schematic way, the origin of the neutrons; their interaction with matter, until its application in the field of dosimetry. It describes some measuring instruments based on thermoluminescence dosimetry, some activation detectors and trace detectors. Finally, it summarizes the work in neutron dosimetry have been carried out at the Autonomous University of Barcelona. (Author)

  17. Utilizing neural networks in magnetic media modeling and field computation: A review

    Directory of Open Access Journals (Sweden)

    Amr A. Adly

    2014-11-01

    Full Text Available Magnetic materials are considered as crucial components for a wide range of products and devices. Usually, complexity of such materials is defined by their permeability classification and coupling extent to non-magnetic properties. Hence, development of models that could accurately simulate the complex nature of these materials becomes crucial to the multi-dimensional field-media interactions and computations. In the past few decades, artificial neural networks (ANNs have been utilized in many applications to perform miscellaneous tasks such as identification, approximation, optimization, classification and forecasting. The purpose of this review article is to give an account of the utilization of ANNs in modeling as well as field computation involving complex magnetic materials. Mostly used ANN types in magnetics, advantages of this usage, detailed implementation methodologies as well as numerical examples are given in the paper.

  18. Utilizing neural networks in magnetic media modeling and field computation: A review.

    Science.gov (United States)

    Adly, Amr A; Abd-El-Hafiz, Salwa K

    2014-11-01

    Magnetic materials are considered as crucial components for a wide range of products and devices. Usually, complexity of such materials is defined by their permeability classification and coupling extent to non-magnetic properties. Hence, development of models that could accurately simulate the complex nature of these materials becomes crucial to the multi-dimensional field-media interactions and computations. In the past few decades, artificial neural networks (ANNs) have been utilized in many applications to perform miscellaneous tasks such as identification, approximation, optimization, classification and forecasting. The purpose of this review article is to give an account of the utilization of ANNs in modeling as well as field computation involving complex magnetic materials. Mostly used ANN types in magnetics, advantages of this usage, detailed implementation methodologies as well as numerical examples are given in the paper.

  19. Radioembolization dosimetry : the road ahead

    NARCIS (Netherlands)

    Smits, Maarten L J; Elschot, Mattijs; Sze, Daniel Y; Kao, Yung H; Nijsen, JFW; Iagaru, Andre H; de Jong, Hugo W A M; van den Bosch, Maurice A A J; Lam, Marnix G E H

    2015-01-01

    Methods for calculating the activity to be administered during yttrium-90 radioembolization (RE) are largely based on empirical toxicity and efficacy analyses, rather than dosimetry. At the same time, it is recognized that treatment planning based on proper dosimetry is of vital importance for the o

  20. A novel optical lithography implement utilizing third harmonic generation via metallic tip enhanced near field

    Science.gov (United States)

    Zhang, Hui; Zhu, Ning; Mei, Ting; He, Miao; Li, Hao; Chen, Zhenshi

    2017-01-01

    A novel scheme for near-field optical lithography utilizing a metallic tip illuminated by femtosecond laser pulses with proper polarization has been presented. The strongly enhanced near field at the metallic tip offers a localized excitation source for the third harmonic generation in the nonlinear material. The generated third harmonic via excitation of nonlinear photoresist provides good exposure contrast due to the cubic intensity dependence. The spatial resolution of this novel lithography scheme is shown to be better than that of the conventional lithography technique.

  1. Utilization of a Buffered Dielectric to Achieve High Field-Effect Carrier Mobility in Graphene Transistors

    OpenAIRE

    Farmer, Damon B.; Chiu, Hsin-Ying; Lin, Yu-Ming; Jenkins, Keith A.; Xia, Fengnian; Avouris, Phaedon

    2009-01-01

    We utilize an organic polymer buffer layer between graphene and conventional gate dielectrics in top-gated graphene transistors. Unlike other insulators, this dielectric stack does not significantly degrade carrier mobility, allowing for high field-effect mobilities to be retained in top-gate operation. This is demonstrated in both two-point and four-point analysis, and in the high-frequency operation of a graphene transistor. Temperature dependence of the carrier mobility suggests that phono...

  2. Dosimetry of electromagnetic field exposure of an active armlet and its electromagnetic interference to the cardiac pacemakers using adult, child and infant models.

    Science.gov (United States)

    Yang, Hu; Wang, Yuduo; Yang, Jiangang; Wu, Tongning

    2016-01-01

    Wearable devices have been popularly used with people from different age groups. As a consequence, the concerns of their electromagnetic field (EMF) exposure to the human body and their electromagnetic interference (EMI) to the implanted medical devices have attracted many studies. The aim of this study was to evaluate the human exposure to the EMF of an active radiofrequency identification (RFID) armlet as well as its EMI to the cardiac pacemaker (CP). Different human models from various age groups were applied to assess the result variability. The scalar potential finite element method was utilized in the simulation. Local EMF exposure and the exposure to the central nerve system tissues were evaluated using different metrics. EMI to the CP was assessed in terms of the conducted voltage to the CP. The results from all the models revealed that the studied RFID armlet would not produce the EMF exposure exceeding the safety limits. The calculated interference voltage was highly dependent on the distance between the RFID armlet and the CP (i.e. the physical dimension of the individual model). The results proposed to evaluate the appropriateness of the current EMI measurement protocol for this kind of devices used by the infants.

  3. Relocation of Dosimetry Service

    CERN Multimedia

    2007-01-01

    The Dosimetry Service is moving from Building 24 to Building 55 and will therefore be closed on Friday, March 30. From Monday, April 2 onwards you will find us in building 55/1-001. Please note that during that day we might still have some problems with the internet connections and cannot fully guarantee normal service procedures. The service's opening hours and telephone number will not change as a result of the move 8.30 - 12.00, afternoons closed Tel. 72155

  4. INDIVIDUAL DOSIMETRY SERVICE

    CERN Multimedia

    2000-01-01

    Personnel in the distribution groups Aleph, Delphi, L3, Opal who also work for other experiments than at LEP, should contact their dispatchers to explain their activities for the future, after LEP dismantling in order to be maintained on the regular distribution list at Individual Dosimetry ServiceWe inform all staffs and users under regular dosimetric control that the dosimeters for the monitoring period JULY/AUGUST are available from their usual dispatchers.Please have your films changed before the 10th of July.The colour of the dosimeter valid in JULY/AUGUST is PINK.

  5. Metrological legal frame in the field of the photon dosimetry of radiotherapy in Cuba; Marco metrologico legal en el campo de la dosimetria fotonica de radioterapia en Cuba

    Energy Technology Data Exchange (ETDEWEB)

    Walwyn S, G.; Gutierrez L, S.; Gonzalez R, N. [CPHR, Calle 20 No. 4113 e/41 y 47, Playa C.P. 11300, La Habana (Cuba)]. e-mail: gonzalo@cphr.edu.cu

    2006-07-01

    The Clinical Dosimetry in the planning of the doses to administer to patients under radiant treatment is of great importance. At the moment the clinical dosemeters its are manufactured with a high technology but errors of production or manipulation cannot be discarded that lead to errors in this planning. It also exists, a group of metrological and of operation parameters that are not checked in a routine calibration, and for those that are checked, legal base that restricts its use in cases of bad operation doesn't exist. This motivated to the Cuban standard elaboration NC 352:2005, for the verification of reference dosemeters of radiotherapy, process that trafficked for an exhaustive search and study of standards and international technical reports, selecting as base document, the standard IEC 60731:1997, for essays of approval of model of clinical dosemeters used in radiotherapy. The present article shows the main technical aspects considered and the requirements and verification methods for the declaration of aptitude of the dosemeters. This document constitutes the scientific base for the implementation from a verification service to national level and an important contribution to the standardization of the metrology of ionizing radiations of Cuba. (Author)

  6. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Science.gov (United States)

    Suzuki, Masashi; Aki, Atsushi; Mizuki, Toru; Maekawa, Toru; Usami, Ron; Morimoto, Hisao

    2015-01-01

    We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  7. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Directory of Open Access Journals (Sweden)

    Masashi Suzuki

    Full Text Available We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  8. Eurados trial performance test for photon dosimetry

    DEFF Research Database (Denmark)

    Stadtmann, H.; Bordy, J.M.; Ambrosi, P.

    2001-01-01

    Within the framework of the EURADOS Action entitled Harmonisation and Dosimetric Quality Assurance in Individual Monitoring for External Radiation, trial performance tests for whole-body and extremity personal dosemeters were carried out. Photon, beta and neutron dosemeters were considered....... This paper summarises the results of the whole-body photon dosemeter test. Twenty-six dosimetry services from all EU Member States and Switzerland participated. Twelve different radiation fields were used to simulate various workplace irradiation fields. Dose values from 0.4 mSv to 80 mSv were chosen. From...

  9. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    Energy Technology Data Exchange (ETDEWEB)

    Rathbone, Bruce A.

    2010-04-01

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at the U.S. Department of Energy (DOE) Hanford site. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with requirements of 10 CFR 835, the DOE Laboratory Accreditation Program, the DOE Richland Operations Office, DOE Office of River Protection, DOE Pacific Northwest Office of Science, and Hanford’s DOE contractors. The dosimetry system is operated by the Pacific Northwest National Laboratory (PNNL) Hanford External Dosimetry Program which provides dosimetry services to PNNL and all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision

  10. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    Energy Technology Data Exchange (ETDEWEB)

    Rathbone, Bruce A.

    2011-04-04

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at the U.S. Department of Energy (DOE) Hanford site. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with requirements of 10 CFR 835, the DOE Laboratory Accreditation Program, the DOE Richland Operations Office, DOE Office of River Protection, DOE Pacific Northwest Office of Science, and Hanford’s DOE contractors. The dosimetry system is operated by the Pacific Northwest National Laboratory (PNNL) Hanford External Dosimetry Program which provides dosimetry services to PNNL and all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision

  11. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    Energy Technology Data Exchange (ETDEWEB)

    Rathbone, Bruce A.

    2007-03-12

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program (HEDP) which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee (HPDAC) which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. Rev. 0 marks the first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database. Revision numbers that are whole numbers reflect major revisions typically involving changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document. Revision Log: Rev. 0 (2/25/2005) Major revision and expansion. Rev. 0.1 (3/12/2007) Minor

  12. Information from the Dosimetry Service

    CERN Multimedia

    2006-01-01

    Please note the following opening hours of the Service: From 31st July onwards: Every morning from 8:30 to 12:00 The Service is closed in the afternoons. We should like to remind you that dosimeters cannot be sent to customers by internal mail. Short-term dosimeters (VCTs) must always be returned to the Service after use and must not be left on the racks in the experimental areas or in the secretariats. Dosimetry Service Tel 72155 Bldg. 24 E 011 Dosimetry.service@cern.ch http://cern.ch/rp-dosimetry

  13. Utilizing field medical equipment to support fixed facilities during major renovation projects.

    Science.gov (United States)

    Call, C A; Maloney, J P

    1993-05-01

    When a fixed facility plans for renovation, the ultimate goal is to provide continuous, cost-effective medical operations. One alternative is to utilize field medical equipment. The Deployable Medical Systems (DEPMEDS), even though designed for battlefield medicine, has been successfully used for six fixed facility renovation projects. As a direct result of various studies, several improvements have been implemented and recommended for the DEPMEDS equipment when used to support fixed facilities. These projects have provided a rich learning experience and have significantly improved the readiness posture of the AMEDD.

  14. Internal dosimetry technical basis manual

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-20

    The internal dosimetry program at the Savannah River Site (SRS) consists of radiation protection programs and activities used to detect and evaluate intakes of radioactive material by radiation workers. Examples of such programs are: air monitoring; surface contamination monitoring; personal contamination surveys; radiobioassay; and dose assessment. The objectives of the internal dosimetry program are to demonstrate that the workplace is under control and that workers are not being exposed to radioactive material, and to detect and assess inadvertent intakes in the workplace. The Savannah River Site Internal Dosimetry Technical Basis Manual (TBM) is intended to provide a technical and philosophical discussion of the radiobioassay and dose assessment aspects of the internal dosimetry program. Detailed information on air, surface, and personal contamination surveillance programs is not given in this manual except for how these programs interface with routine and special bioassay programs.

  15. Radioembolization Dosimetry: The Road Ahead

    Energy Technology Data Exchange (ETDEWEB)

    Smits, Maarten L. J., E-mail: m.l.j.smits-3@umcutrecht.nl; Elschot, Mattijs [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine (Netherlands); Sze, Daniel Y. [Stanford University School of Medicine, Division of Interventional Radiology (United States); Kao, Yung H. [Austin Hospital, Department of Nuclear Medicine (Australia); Nijsen, Johannes F. W. [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine (Netherlands); Iagaru, Andre H. [Stanford University School of Medicine, Division of Nuclear Medicine and Molecular Imaging (United States); Jong, Hugo W. A. M. de; Bosch, Maurice A. A. J. van den; Lam, Marnix G. E. H. [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine (Netherlands)

    2015-04-15

    Methods for calculating the activity to be administered during yttrium-90 radioembolization (RE) are largely based on empirical toxicity and efficacy analyses, rather than dosimetry. At the same time, it is recognized that treatment planning based on proper dosimetry is of vital importance for the optimization of the results of RE. The heterogeneous and often clustered intrahepatic biodistribution of millions of point-source radioactive particles poses a challenge for dosimetry. Several studies found a relationship between absorbed doses and treatment outcome, with regard to both toxicity and efficacy. This should ultimately lead to improved patient selection and individualized treatment planning. New calculation methods and imaging techniques and a new generation of microspheres for image-guided RE will all contribute to these improvements. The aim of this review is to give insight into the latest and most important developments in RE dosimetry and to suggest future directions on patient selection, individualized treatment planning, and study designs.

  16. Radioembolization dosimetry: the road ahead.

    Science.gov (United States)

    Smits, Maarten L J; Elschot, Mattijs; Sze, Daniel Y; Kao, Yung H; Nijsen, Johannes F W; Iagaru, Andre H; de Jong, Hugo W A M; van den Bosch, Maurice A A J; Lam, Marnix G E H

    2015-04-01

    Methods for calculating the activity to be administered during yttrium-90 radioembolization (RE) are largely based on empirical toxicity and efficacy analyses, rather than dosimetry. At the same time, it is recognized that treatment planning based on proper dosimetry is of vital importance for the optimization of the results of RE. The heterogeneous and often clustered intrahepatic biodistribution of millions of point-source radioactive particles poses a challenge for dosimetry. Several studies found a relationship between absorbed doses and treatment outcome, with regard to both toxicity and efficacy. This should ultimately lead to improved patient selection and individualized treatment planning. New calculation methods and imaging techniques and a new generation of microspheres for image-guided RE will all contribute to these improvements. The aim of this review is to give insight into the latest and most important developments in RE dosimetry and to suggest future directions on patient selection, individualized treatment planning, and study designs.

  17. El Centro Geothermal Utility Core Field Experiment environmental-impact report and environmental assessment

    Energy Technology Data Exchange (ETDEWEB)

    1979-08-01

    The City of El Centro is proposing the development of a geothermal energy utility core field experiment to demonstrate the engineering and economic feasibility of utilizing moderate temperature geothermal heat, on a pilot scale, for space cooling, space heating, and domestic hot water. The proposed facility is located on part of a 2.48 acre (1 hectare) parcel owned in fee by the City in the southeastern sector of El Centro in Imperial County, California. Geothermal fluid at an anticipated temperature of about 250/sup 0/F (121/sup 0/C) will heat a secondary fluid (water) which will be utilized directly or processed through an absorption chiller, to provide space conditioning and water heating for the El Centro Community Center, a public recreational facility located approximately one-half mile north of the proposed well site. The geothermal production well will be drilled to 8500 feet (2590m) and an injection well to 4000 feet (1220m) at the industrially designated City property. Once all relevant permits are obtained it is estimated that site preparation, facility construction, the completion and testing of both wells would be finished in approximately 26 weeks. The environmental impacts are described.

  18. Hanford internal dosimetry program manual

    Energy Technology Data Exchange (ETDEWEB)

    Carbaugh, E.H.; Sula, M.J.; Bihl, D.E.; Aldridge, T.L.

    1989-10-01

    This document describes the Hanford Internal Dosimetry program. Program Services include administrating the bioassay monitoring program, evaluating and documenting assessments of internal exposure and dose, ensuring that analytical laboratories conform to requirements, selecting and applying appropriate models and procedures for evaluating internal radionuclide deposition and the resulting dose, and technically guiding and supporting Hanford contractors in matters regarding internal dosimetry. 13 refs., 16 figs., 42 tabs.

  19. Optical fiber detectors as in-vivo dosimetry method of quality assurance in radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Plazas, M.C. [Universidad Nacional de Colombia, Bogota (Colombia). Physics Dept. Medical Physics Group; Justus, B.L.; Falkenstein, P.; Huston, A.L. [Naval Research Laboratory, Washington, DC (United States). Optical Sciences Div.; Ning, H.; Miller, R. [National Cancer Institute, Bethesda, MD (United States). Radiation Oncology Branch

    2004-07-01

    A new in-vivo dosimetry system has been under development for some time using radio luminescent phosphors. These phosphors are activated, metal ion doped glasses (Ex: Cu{sup 1{+-}} doped quartz fiber), have excellent optical transparency and offer several potential advantages for radiation dosimetry; including: small size, high sensitivity, linearity of dose response insensitivity to electromagnetic interference. The utility of these phosphors as a detection modality has been limited in real-time dosimetry applications due to the production of Cerenkov radiation in the carrier fiber, which produces a contaminant signal proportional to dose rate as well as the size of the radiation field. One possible method for eliminating this signal is using an electronic gating signal from the accelerator to delay data acquisition during the actual beam pulse, when Cerenkov radiation is produced. Due to the intrinsic properties of our particular scintillator, this method offers the best mechanism for eliminating Cerenkov noise, while retaining the ability to detect individual beam pulses. The dosimeter was tested using an external beam radiotherapy machine that provided pulses of 6 MeV x-rays. Gated detection was used to discriminate the signal collected during the radiation pulses, which included contributions from Cerenkov radiation and native fiber fluorescence, from the signal collected between the radiation pulses, which contained only the long-lived phosphorescence from the Cu{sup 1{+-}} doped fused quartz detector. Gated detection of the phosphorescence provided accurate, real-time dose measurements that were linear with absorbed dose, independent of dose rate and that were accurate for all field sizes studied. (author)

  20. Dosimetry of iodoantipyrine.

    Science.gov (United States)

    Chu, R Y; Ekeh, S; Basmadjian, G

    1989-01-01

    Dosimetry of iodoantipyrine labeled with radioactive iodine was determined by measuring the biodistribution of 131I-iodoantipyrine in 41 female rabbits. Following administration of the radiopharmaceutical, subjects were killed at 0.5, 6, 12, 17, 24, 36, and 48 h. Organs and samples of tissues and body fluids were assayed. Results were corrected for physical decay. Exponential functions were employed to describe the time-concentration curves; representative value would be the biological half life of 9.96 +/- 0.55 h for blood. Cumulated activity estimates for 123I, 125I and 131I were then computed. Extrapolation to absorbed dose in humans followed the formulation of the Medical International Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine. The whole body absorbed doses are 7 mu Gray, 5 mu Gray and 29 mu Gray per MBq of 123I, 125I, and 131I administered respectively.

  1. Medical dosimetry in Hungary

    Science.gov (United States)

    Turák, O.; Osvay, M.; Ballay, L.

    2012-09-01

    Radiation exposure of medical staff during cardiological and radiological procedures was investigated. The exposure of medical staff is directly connected to patient exposure. The aim of this study was to determine the distribution of doses on uncovered part of body of medical staff using LiF thermoluminescent (TL) dosimeters in seven locations. Individual Kodak film dosimeters (as authorized dosimetry system) were used for the assessment of medical staff's effective dose. Results achieved on dose distribution measurements confirm that wearing only one film badge under the lead apron does not provide enough information on the personal dose. The value of estimated annual doses on eye lens and extremities (fingers) were in good correlation with international publications.

  2. Strahlungsmessung und Dosimetrie

    CERN Document Server

    Krieger, Hanno

    2013-01-01

    „Strahlungsquellen und Dosimetrie“ ist Teil einer Lehrbuchreihe zur Strahlungsphysik und zum Strahlenschutz. Der erste Teil befasst sich mit den physikalischen Grundlagen der Strahlungsdetektoren und der Strahlungsmessung. Im zweiten Teil werden die Konzepte und Verfahren der klinischen Dosimetrie dargestellt. Der dritte Abschnitt erläutert ausführlich die Dosisverteilungen der klinisch angewendeten Strahlungsarten. Im vierten Teil werden weitere Messaufgaben der Strahlungsphysik einschließlich der Messsysteme für die Bildgebung mit Röntgenstrahlung dargestellt. Neben den grundlegenden Ausführungen enthält dieser Band im laufenden Text zahlreiche Tabellen und Grafiken zur technischen und medizinischen Radiologie, die bei der praktischen Arbeit sehr hilfreich sein können und 199 Übungsaufgaben mit Lösungen zur Vertiefung der Inhalte. Für die zweite Auflage wurden die Darstellungen der Elektronen- und der Protonendosimetrie sowie der bildgebenden Verfahren mit Computertomografen deutlich erweit...

  3. Dosimetry considerations in phototherapy

    Energy Technology Data Exchange (ETDEWEB)

    Profio, A.E.; Doiron, D.R.

    Dosimetry in phototherapy involves a determination of the energy absorbed per unit mass of tissue, corrected for the quantum yield in a photochemical reaction. The dose rate in photochemotherapy of cancer with hematoporphyrin derivative and visible light is related to the extinction coefficient, quantum yield for singlet oxygen production, concentration of sensitizer and energy flux density at depth. Data or methods of determining these quantities are presented. Calculations have been performed for the energy flux density at depth, as a function of the total attenuation coefficient and ratio of scattering coefficient to total attenuation coefficient, for isotropic scattering in slab geometry. For small absorption, these depth dose curves exhibit a maximum within the tissue followed by an exponential decrease.

  4. Dosimetry considerations in phototherapy

    Energy Technology Data Exchange (ETDEWEB)

    Profio, A.E.; Doiron, D.R.

    1981-03-01

    Dosimetry in phototherapy involves a determination of the energy absorbed per unit mass of tissue, corrected for the quantum yield in a photochemical reaction. The dose rate in photochemotherapy of cancer with hematoporphyrin derivative and visible light is related to the extinction coefficient, quantum yield for singlet oxygen production, concentration of sensitizer and energy flux density at depth. Data or methods of determining these quantities are presented. Calculations have been performed for the energy flux density at depth, as a function of the total attenuation coefficient and ratio of scattering coefficient to total attenuation coefficient, for isotropic scattering in slab geometry. For small absorption, these depth dose curves exhibit a maximum within the tissue followed by an exponential decrease.

  5. Technical basis for external dosimetry at the Waste Isolation Pilot Plant (WIPP)

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, E.W. [Science Applications International Corp., Oak Ridge, TN (United States); Wu, C.F.; Goff, T.E. [Westinghouse Electric Corp., Carlsbad, NM (United States). Waste Isolation Div.

    1993-12-31

    The WIPP External Dosimetry Program, administered by Westinghouse Electric Corporation, Waste Isolation Division, for the US Department of Energy (DOE), provides external dosimetry support services for operations at the Waste Isolation Pilot Plant (WIPP) Site. These operations include the receipt, experimentation with, storage, and disposal of transuranic (TRU) wastes. This document describes the technical basis for the WIPP External Radiation Dosimetry Program. The purposes of this document are to: (1) provide assurance that the WIPP External Radiation Dosimetry Program is in compliance with all regulatory requirements, (2) provide assurance that the WIPP External Radiation Dosimetry Program is derived from a sound technical base, (3) serve as a technical reference for radiation protection personnel, and (4) aid in identifying and planning for future needs. The external radiation exposure fields are those that are documented in the WIPP Final Safety Analysis Report.

  6. In vivo dosimetry: trends and prospects for brachytherapy

    DEFF Research Database (Denmark)

    Kertzscher, Gustavo; Rosenfeld, A.; Beddar, S.

    2014-01-01

    The error types during brachytherapy (BT) treatments and their occurrence rates are not well known. The limited knowledge is partly attributed to the lack of independent verification systems of the treatment progression in the clinical workflow routine. Within the field of in vivo dosimetry (IVD)...

  7. Fiber-coupled Luminescence Dosimetry in Therapeutic and Diagnostic Radiology

    DEFF Research Database (Denmark)

    Andersen, Claus Erik

    2011-01-01

    Fiber-coupled luminescence dosimetry is an emerging technology with several potentially attractive features of relevance for uses in therapeutic and diagnostic radiology: direct water equivalence (i.e. no significant perturbation of the radiation field in a water phantom or a patient), sub...

  8. Eurados trial performance test for neutron personal dosimetry

    DEFF Research Database (Denmark)

    Bordy, J.M.; Stadtmann, H.; Ambrosi, P.;

    2001-01-01

    measured, but particular problems were noted in the determination of intermediate energy fields and large incident angles, demonstrating the difficulties of neutron personal dosimetry. Of particular concern from a radiological protection point of view was the large number of results underestimating...... personal dose equivalent. A considerable over-response was noted in a few cases....

  9. Graphite mixed magnesium borate TL dosemeters for beta ray dosimetry

    DEFF Research Database (Denmark)

    Prokic, M; Christensen, Poul

    1984-01-01

    Sintered MgB4O7:Dy dosemeters with graphite contents from 1 to 10% were investigated for application for personnel dosimetry. Data are given on dose response, dose threshold, reproducibility, beta energy response and fading. Furthermore, results from practical field experiments are presented...

  10. In vivo dosimetry with silicon diodes in total body irradiation

    Science.gov (United States)

    Oliveira, F. F.; Amaral, L. L.; Costa, A. M.; Netto, T. G.

    2014-02-01

    The aim of this work is the characterization and application of silicon diode detectors for in vivo dosimetry in total body irradiation (TBI) treatments. It was evaluated the diode response with temperature, dose rate, gantry angulations and field size. A maximum response variation of 2.2% was obtained for temperature dependence. The response variation for dose rate and angular was within 1.2%. For field size dependence, the detector response increased with field until reach a saturation region, where no more primary radiation beam contributes for dose. The calibration was performed in a TBI setup. Different lateral thicknesses from one patient were simulated and then the calibration factors were determined by means of maximum depth dose readings. Subsequent to calibration, in vivo dosimetry measurements were performed. The response difference between diode readings and the prescribed dose for all treatments was below 4%. This difference is in agreement as recommended by the International Commission on Radiation Units and Measurements (ICRU), which is ±5%. The present work to test the applicability of a silicon diode dosimetry system for performing in vivo dose measurements in TBI techniques presented good results. These measurements demonstrated the value of diode dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in TBI treatments.

  11. Characterising an aluminium oxide dosimetry system.

    Science.gov (United States)

    Conheady, Clement F; Gagliardi, Frank M; Ackerly, Trevor

    2015-09-01

    In vivo dosimetry is recommended as a defence-in-depth strategy in radiotherapy treatments and is currently employed by clinics around the world. The characteristics of a new optically stimulated luminescence dosimetry system were investigated for the purpose of replacing an aging thermoluminescence dosimetry system for in vivo dosimetry. The stability of the system was not sufficient to satisfy commissioning requirements and therefore it has not been released into clinical service at this time.

  12. SU-D-213-06: Dosimetry of Modulated Electron Radiation Therapy Using Fricke Gel Dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Gawad, M Abdel; Elgohary, M; Hassaan, M; Emam, M [Al Azhar University, Cairo Egypt (Egypt); Desouky, O [National center for radiation research and technology-Egyptian atomic energy, Cairo (Egypt); Eldib, A [Al Azhar University, Cairo Egypt (Egypt); Fox Chase Cancer Center, Philadelphia, PA (United States); Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States)

    2015-06-15

    Purpose: Modulated electron radiation therapy (MERT) has been proposed as an effective modality for treatment of superficial targets. MERT utilizes multiple beams of different energies which are intensity modulated to deliver optimized dose distribution. Energy independent dosimeters are thus needed for quantitative evaluations of MERT dose distributions and measurements of absolute doses delivered to patients. Thus in the current work we study the feasibility of Fricke gel dosimeters in MERT dosimetry. Methods: Batches of radiation sensitive Fricke gel is fabricated and poured into polymethyl methacrylate cuvettes. The samples were irradiated in solid water phantom and a thick layer of bolus was used as a buildup. A spectrophotometer system was used for measuring the color changes (the absorbance) before and after irradiation and then we calculate net absorbance. We constructed calibration curves to relate the measured absorbance in terms of absorbed dose for all available electron energies. Dosimetric measurements were performed for mixed electron beam delivery and we also performed measurement for segmented field delivery with the dosimeter placed at the junction of two adjacent electron beams of different energies. Dose measured by our gel dosimetry is compared to that calculation from our precise treatment planning system. We also initiated a Monte Carlo study to evaluate the water equivalence of our dosimeters. MCBEAM and MCSIM codes were used for treatment head simulation and phantom dose calculation. PDDs and profiles were calculated for electron beams incident on a phantom designed with 1cm slab of Fricke gel. Results: The calibration curves showed no observed energy dependence with all studied electron beam energies. Good agreement was obtained between dose calculated and that obtained by gel dosimetry. Monte Carlo results illustrated the tissue equivalency of our Gel dosimeters. Conclusion: Fricke Gel dosimeters represent a good option for the dosimetric

  13. Hanford External Dosimetry Technical Basis Manual PNL-MA-842

    Energy Technology Data Exchange (ETDEWEB)

    Rathbone, Bruce A.

    2010-01-01

    The Hanford External Dosimetry Technical Basis Manual PNL-MA-842 documents the design and implementation of the external dosimetry system used at Hanford. The manual describes the dosimeter design, processing protocols, dose calculation methodology, radiation fields encountered, dosimeter response characteristics, limitations of dosimeter design under field conditions, and makes recommendations for effective use of the dosimeters in the field. The manual describes the technical basis for the dosimetry system in a manner intended to help ensure defensibility of the dose of record at Hanford and to demonstrate compliance with 10 CFR 835, DOELAP, DOE-RL, ORP, PNSO, and Hanford contractor requirements. The dosimetry system is operated by PNNL’s Hanford External Dosimetry Program (HEDP) which provides dosimetry services to all Hanford contractors. The primary users of this manual are DOE and DOE contractors at Hanford using the dosimetry services of PNNL. Development and maintenance of this manual is funded directly by DOE and DOE contractors. Its contents have been reviewed and approved by DOE and DOE contractors at Hanford through the Hanford Personnel Dosimetry Advisory Committee (HPDAC) which is chartered and chaired by DOE-RL and serves as means of coordinating dosimetry practices across contractors at Hanford. This manual was established in 1996. Since its inception, it has been revised many times and maintained by PNNL as a controlled document with controlled distribution. The first revision to be released through PNNL’s Electronic Records & Information Capture Architecture (ERICA) database was designated Revision 0. Revision numbers that are whole numbers reflect major revisions typically involving significant changes to all chapters in the document. Revision numbers that include a decimal fraction reflect minor revisions, usually restricted to selected chapters or selected pages in the document. Maintenance and distribution of controlled hard copies of the

  14. Dosimetry of iodoantipyrine

    Energy Technology Data Exchange (ETDEWEB)

    Chu, R.Y.L.; Ekeh, S. (Oklahoma Univ., Oklahoma City, OK (USA). Dept. of Radiological Sciences; Veterans Administration Medical Center, Oklahoma City, OK (USA)); Basmadjian, G. (Oklahoma Univ., Oklahoma City, OK (USA). Dept. of Pharmaceutical Sciences)

    1989-12-01

    Dosimetry of iodoantipyrine labeled with radioactive iodine was determined by measuring the biodistribution of {sup 131}I-iodoantipyrine in 41 female rabbits. Following administration of the radiopharmaceutical, subjects were killed at 0.5, 6, 12, 17, 24, 36, and 48 h. Organs and samples of tissues and body fluids were assayed. Results were corrected for physical decay. Exponential functions were employed to describe the time-concentration curves; representative value would be the biological half life of 9.96+-0.55 h for blood. Cumulated activity estimates for {sup 123}I, {sup 125}I and {sup 131}I were then computed. Extrapolation to absorbed dose in humans followed the formulation of the Medical International Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine. The whole body absorbed doses are 0.7 {mu}Gray, 0.5 {mu}Gray and 2.9 {mu}Gray per MBq of {sup 123}I, {sup 123}I, and {sup 131}I administered respectively. (orig.).

  15. Magnetomotive optical coherence elastography (MM-OCE) for thermal therapy dosimetry (Conference Presentation)

    Science.gov (United States)

    Huang, Pin-Chieh; Marjanovic, Marina; Spillman, Darold R.; Odintsov, Boris M.; Boppart, Stephen A.

    2016-03-01

    Biomechanical properties of tissues have been utilized for disease detection, diagnosis, and progression, however they have not been extensively utilized for therapy dosimetry. Magnetic hyperthermia aims to kill cells and ablate tumors using magnetic nanoparticles (MNPs) either injected in or targeted to tumors. Upon application of an appropriate AC magnetic field, MNPs can heat target tissue while sparing non-targeted healthy tissue. However, a sensitive monitoring technique for the dose of magnetic hyperthermia is needed to prevent over-treatment and collateral injury. During hyperthermia treatments, the viscoelastic properties of tissues are altered due to protein denaturation, coagulation, and tissue dehydration, making these properties candidates for dosimetry. Magnetomotive optical coherence elastography (MM-OCE) utilizes MNPs as internal force transducers to probe the biomechanical properties of tissues. Therefore, we aim to evaluate the hyperthermia dose based on the elastic changes revealed by MM-OCE. In this study, MNPs embedded in tissues were utilized for both hyperthermia and MM-OCE measurements. Tissue temperature and elastic modulus were obtained, where the elastic modulus was extracted from the resonance frequency detected by MM-OCE. Results showed a correlation between stiffness and temperature change following treatment. To investigate the thermal-dose-dependent changes, intervals of hyperthermia treatment were repeatedly performed on the same tissue sequentially, interspersed with MM-OCE. With increasing times of treatment, tissue stiffness increased, while temperature rise remained relatively constant. These results suggest that MM-OCE may potentially identify reversible and irreversible tissue changes during thermal therapy, supporting the use of MM-OCE for dosimetric control of hyperthermia in future applications.

  16. [The image noise effect on the results of Gamma knife dosimetry parameters test].

    Science.gov (United States)

    Cheng, Xiaojun; Zhang, Conghua; Hu, Chuanpeng; Dai, Fuyou; Wei, Kunjie; Chu, Caifang

    2012-12-01

    In order to analyze the image noise effect on the results of Gamma knife dosimetry parameter test, we tested the dosimetry parameters of the Gamma knives according to GBZ 168-2005. Radiological protection standards of X (gamma)-ray stereotactic radiosurgery for head treatment. Dose analysis software was applied to examine the testing film before and after image denoising, and SPSS 11.0 software was used for statistical analysis. The results showed that there was a significant difference in the results of the maximum deviation between radiation field size and its nominal value (t = 7.600, P Gamma knife dosimetry parameters, so as to cause deviations.

  17. Comparison of determinants of research knowledge utilization by practitioners and administrators in the field of child and family social services

    Directory of Open Access Journals (Sweden)

    Gervais Marie-Joëlle

    2010-06-01

    Full Text Available Abstract Background An important gap exists between research production and its utilization. Few studies have examined the factors affecting knowledge utilization in the field of child and family social services. Methods The objectives of the study are to describe knowledge utilization by child protection administrators and practitioners (N = 477 and to compare factors related to knowledge utilization by these two occupational groups. The study was conducted with an adapted version of the Questionnaire sur l'utilisation des connaissances (Knowledge Utilization Questionnaire. Factor analysis was used to collapse data collected on the questionnaire items. Factor score for each respondent served as independent variables in three separate multivariate regression analyses to explore variables likely to predict research-based knowledge utilization. Results A minority of respondents (18% report using on a frequent basis research-based knowledge in their practice. Relational capital between researchers and users and perceived usefulness of research based knowledge were the two factors most strongly related to utilization. There was a specificity in the factors associated with knowledge utilization according to occupational groups in child protection organizations. Use of active knowledge transfer strategies was associated with knowledge utilization by practitioners, while knowledge dissemination efforts played a more significant role for administrators. Conclusion These results encourage both the use of strategies differentiated according to users and the intensification of interactions between users and researchers to foster research knowledge utilization.

  18. Information from the Dosimetry Service

    CERN Multimedia

    2006-01-01

    Please note the following opening hours of the Service: In June: Every morning from 8:30 to 12:00 In July: Mondays, Wednesdays and Fridays from 8:30 to 11:30 Closed all day on Tuesdays and Thursdays From 31st July onwards: Every morning from 8:30 to 12:00 The Service is closed in the afternoons. We should like to remind you that dosimeters cannot be sent to customers by internal mail. Short-term dosimeters (VCTs) must always be returned to the Service after use and must not be left on the racks in the experimental areas or in the secretariats. Dosimetry Service Tel 72155 Bldg. 24 E 011 Dosimetry.service@cern.ch http://cern.ch/rp-dosimetry

  19. For information: Individual dosimetry service

    CERN Multimedia

    2004-01-01

    The service has noticed that there are dosimeter holders who have changed their activities and thus have no longer need of dosimeter as a permanent basis in their work (persons who go rarely to the controlled areas). The reduction of persons in the regular distribution list of dosimeters will lighten the work of the service (distribution, evaluation and consolidation of doses) as well as the work of the distributors, needless to say the economical input this would have for CERN. For the persons who only need a dosimeter temporarily we would like to remind that there is a quick and simple procedure to have one immediately from the Individual Dosimetry Service. Please contact the service (dosimetry.service@cern.ch) if you do not need a dosimeter regularly. Thank you for your cooperation. http://cern.ch/rp-dosimetry

  20. Review of recent advances in radiochromic materials for 3D dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Kevin, E-mail: Kevin.jordan@lhsc.on.c [London Regional Cancer Program, London Health Sciences Centre (United Kingdom); Department of Medical Biophysics, University of Western Ontario, London, ON (Canada)

    2010-11-01

    Recent papers concerning radiochromic films, plastics and hydrogels for 3D dosimetry are summarized. The utility of Presage, a radiochromic plastic, with optical CT readout was demonstrated for the following applications: motion and gated treatment delivery, commissioning of small fields for radiosurgery, {sup 192}Ir high dose rate brachytherapy source commissioning and as a 3D insert for IMRT credentialing tests with Radiological Physics Centre (RPC) phantoms. Preliminary performance for characterizing microbeams from a synchrotron with optic projection tomography readout demonstrated resolution of an 83 micron diameter beam. Hydrogel chemistries based on nonionic micelles for leuco malachite green and leuco crystal violet demonstrated that low diffusion gels can be designed by choosing product dyes that are poorly soluble and water and tend to remain in the micelles. Turnbull blue chemistry has been successfully adapted to form a non-diffusing gel as well. The performance of ferrous xylenol orange hydrogel layers doped with boron to form neutron dosimeters demonstrated another practical application. Polymerization hydrogels are alternate materials that can be read with optical CT scanners. High dose gradient applications in brachytherapy with 90Sr/90Y sources and proton dosimetry are presented for comparison.

  1. Review of recent advances in radiochromic materials for 3D dosimetry

    Science.gov (United States)

    Jordan, Kevin

    2010-11-01

    Recent papers concerning radiochromic films, plastics and hydrogels for 3D dosimetry are summarized. The utility of Presage", a radiochromic plastic, with optical CT readout was demonstrated for the following applications: motion and gated treatment delivery, commissioning of small fields for radiosurgery, 192Ir high dose rate brachytherapy source commissioning and as a 3D insert for IMRT credentialing tests with Radiological Physics Centre (RPC) phantoms. Preliminary performance for characterizing microbeams from a synchrotron with optic projection tomography readout demonstrated resolution of an 83 micron diameter beam. Hydrogel chemistries based on nonionic micelles for leuco malachite green and leuco crystal violet demonstrated that low diffusion gels can be designed by choosing product dyes that are poorly soluble and water and tend to remain in the micelles. Turnbull blue chemistry has been successfully adapted to form a non-difffusing gel as well. The performance of ferrous xylenol orange hydrogel layers doped with boron to form neutron dosimeters demonstrated another practical application. Polymerization hydrogels are alternate materials that can be read with optical CT scanners. High dose gradient applications in brachytherapy with 90Sr/90Y sources and proton dosimetry are presented for comparison.

  2. Information from the Dosimetry Service

    CERN Multimedia

    2006-01-01

    CERN Staff and Users can now consult their dose records for an individual or an organizational unit with HRT. Please see more information on our web page http://cern.ch/rp-dosimetry. The Dosimetry Service is open every morning from 8.30 - 12.00, and closed in the afternoons. We would like to remind you that dosimeters cannot be sent to customers by internal mail. Short-term dosimeters (VCT's) must always be returned to the Service after use and must not be left on the racks in the experimental areas or in the secretariats.

  3. Information from the Dosimetry Service

    CERN Multimedia

    2006-01-01

    CERN Staff and Users can now consult their dose records for an individual or an organizational unit with HRT. Please see more information on our web page: http://cern.ch/rp-dosimetry. The Dosimetry Service is open every morning from 8.30 to 12.00 and is closed in the afternoons. We would like to remind you that dosimeters cannot be sent to customers by internal mail. Short-term dosimeters (VCT's) must always be returned to the Service after use and must not be left on the racks in the experimental areas or in the secretariats.

  4. Monte Carlo physical dosimetry for small photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Perucha, M.; Rincon, M.; Leal, A.; Carrasco, E. [Sevilla Univ. (Spain). Dept. Fisiologia Medica y Biofisica; Sanchez-Doblado, F. [Sevilla Univ. (Spain). Dept. Fisiologia Medica y Biofisica]|[Hospital Univ. Virgen Macarena, Sevilla (Spain). Servicio de Oncologia Radioterapica; Nunez, L. [Clinica Puerta de Hierro, Madrid (Spain). Servicio de Radiofisica; Arrans, R.; Sanchez-Calzado, J.A.; Errazquin, L. [Hospital Univ. Virgen Macarena, Sevilla (Spain). Servicio de Oncologia Radioterapica

    2001-07-01

    Small field dosimetry is complicated due to the lack of electronic equilibrium and to the high steep dose gradients. This works compares PDD curves, profiles and output factors measured with conventional detectors (film, diode, TLD and ionisation chamber) and calculated with Monte Carlo. The 6 MV nominal energy from a Philips SL-18 linac has been simulated by using the OMEGA code. MC calculation reveals itself as a convenient method to validate OF and profiles in special conditions, such as small fields. (orig.)

  5. Proton minibeam radiation therapy: Experimental dosimetry evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Peucelle, C.; Martínez-Rovira, I.; Prezado, Y., E-mail: prezado@imnc.in2p3.fr [IMNC-UMR 8165, CNRS, Paris 7 and Paris 11 Universities, 15 rue Georges Clemenceau, Orsay Cedex 91406 (France); Nauraye, C.; Patriarca, A.; Hierso, E.; Fournier-Bidoz, N. [Institut Curie - Centre de Protonthérapie d’Orsay, Campus Universitaire, Bât. 101, Orsay 91898 (France)

    2015-12-15

    Purpose: Proton minibeam radiation therapy (pMBRT) is a new radiotherapy (RT) approach that allies the inherent physical advantages of protons with the normal tissue preservation observed when irradiated with submillimetric spatially fractionated beams. This dosimetry work aims at demonstrating the feasibility of the technical implementation of pMBRT. This has been performed at the Institut Curie - Proton Therapy Center in Orsay. Methods: Proton minibeams (400 and 700 μm-width) were generated by means of a brass multislit collimator. Center-to-center distances between consecutive beams of 3200 and 3500 μm, respectively, were employed. The (passive scattered) beam energy was 100 MeV corresponding to a range of 7.7 cm water equivalent. Absolute dosimetry was performed with a thimble ionization chamber (IBA CC13) in a water tank. Relative dosimetry was carried out irradiating radiochromic films interspersed in a IBA RW3 slab phantom. Depth dose curves and lateral profiles at different depths were evaluated. Peak-to-valley dose ratios (PVDR), beam widths, and output factors were also assessed as a function of depth. Results: A pattern of peaks and valleys was maintained in the transverse direction with PVDR values decreasing as a function of depth until 6.7 cm. From that depth, the transverse dose profiles became homogeneous due to multiple Coulomb scattering. Peak-to-valley dose ratio values extended from 8.2 ± 0.5 at the phantom surface to 1.08 ± 0.06 at the Bragg peak. This was the first time that dosimetry in such small proton field sizes was performed. Despite the challenge, a complete set of dosimetric data needed to guide the first biological experiments was achieved. Conclusions: pMBRT is a novel strategy in order to reduce the side effects of RT. This works provides the experimental proof of concept of this new RT method: clinical proton beams might allow depositing a (high) uniform dose in a brain tumor located in the center of the brain (7.5 cm depth

  6. 楔形野与野中野在三维适形治疗计划的剂量对比研究%Dosimetry Study of Wedge Field and Field-In-Field in 3D-CRT Plans

    Institute of Scientific and Technical Information of China (English)

    胡胜文; 荆保国; 梁玉新

    2011-01-01

    目的:比较研究楔形过滤板射野(Wedge Filter)与野中野(FIF:Field-in-Field)在放疗时靶区及周围正常组织照射剂量的差异.方法:随机选择骨(腰椎)转移癌,脑癌,乳腺癌,食管癌,肺癌共24例,进行CT扫描,靶区和危及器官(OAR)的勾画,用三维治疗计划系统进行楔形野计划(Wedge Plan)和野中野计划(FIF Plan)设计,并进行结果对比分析.结果:FIF计划的剂量均匀性(HI)和适形度(CI)要优于Wedge计划,P值分别为0.001,0.007,同时FIF计划的跳数明显小于Wedge计划的跳数,其差异具有统计学意义(P=0.00),而PTV的靶区覆盖率(V95%)和正常组织照射量差异没有明显的统计学意义(P>0.05).结论:与Wedge计划相比,FIF计划具有更好的适形度和剂量均匀性,在临床中应用中,可减低机器损耗,提高工作效率,值得在临床工作中推广使用.%Objective: To make the comparative research the differences of target dose and surrounding normal tissue dose between Wedge Field and Field-ln-Filed in radiotherapy. Methods: Random selection of bone (lumbar) metastatic carcinoma, brain cancer, breast cancer, esophageal cancer, lung cancer of 24 cases, performed the CT scan and outlined the target and organ at risk(OAR), using three-dimensional treatment planning system to design Field-In-Field plan and Wedge plan, and the results were compared and analyzed. Results: The dose of Habituation Index(HI) and Conformity Index(CI) of FIF plan was superior to the Wedge plan, P value was 0.001,0.007 respectively. Meanwhile the Monitor Unit of FIF plan was obviously less than the Wedge plan, the differences were statistically significant (P=0.00), but the difference of the coverage of PTV(K95%) and radiation dose of normal tissue were not statistically significant(P>0.05). Conclusions: Compared with Wedge plan, FIF plan has better Habituation Index and Conformity Index of PTV. Hi the clinical applications, it can reduce machine's depreciation; improve work

  7. A high sensitivity field effect transistor biosensor for methylene blue detection utilize graphene oxide nanoribbon.

    Science.gov (United States)

    Lin, Ting-Chun; Li, Yan-Sheng; Chiang, Wei-Hung; Pei, Zingway

    2017-03-15

    In this work, we developed a field effect transistor (FET) biosensor utilizing solution-processed graphene oxide nanoribbon (GONR) for methylene blue (MB) sensing. MB is a unique material; one of its crucial applications is as a marker in the detection of biomaterials. Therefore, a highly sensitive biosensor with a low detection limit that can be fabricated simply in a noncomplex detection scheme is desirable. GONR is made by unzipping multiwall carbon nanotubes, which can be mass-produced at low temperature. The GONR-FET biosensor demonstrated a sensitivity of 12.5μA/mM (determined according to the drain current difference caused by the MB concentration change). The Raman spectra indicate that the materials quality of the GONR and the domain size for the C=C sp(2) bonding were both improved after MB detection. X-ray photoelectron spectroscopy revealed that the hydroxyl groups on the GONR were removed by the reductive MB. According to XPS and Raman, the positive charge is proposed to transfer from MB to GONR during sensing. This transfer causes charge in-neutrality in the GONR which is compensated by releasing •OH functional groups. With high sensitivity, a low detection limit, and a simple device structure, the GONR-FET sensor is suitable for sensing biomaterials.

  8. The Field Utility Vehicle: a tool for EOD personnel using neutron-based UXO discrimination systems

    Science.gov (United States)

    Womble, Phillip C.; Paschal, Jonathon; Cantrell, Kirk; Wallace, Britton L.

    2004-09-01

    In the past decade, two portable systems for the discrimination of unexploded ordnance (UXO) have been developed: the PINS system and the PELAN system. While technically portable, each of these systems has ancillary equipment and wires which make them cumbersome for explosive ordnance disposal (EOD) personnel. Also, moving these systems from place to place is time-consuming. We have developed a mobile platform called the Field Utility Vehicle (FUV) to mitigate these burdens. The FUV provides power and communications for these devices, is self-propelled, and has a powered lift mechanism to adjust the height of these systems to any shell size. The FUV concept originated during a demonstration of the PELAN system at the White Oak Naval Surface Warfare Center conducted by US Navy EOD Technology Division personnel. Currently, a prototype FUV has been built and tested at the Western Kentucky University"s Applied Physics Institute. The results of these tests and cost-benefit of employing the FUV in UXO clean-up operations will be shown.

  9. The Urban Ecology Institute's field studies program: utilizing urban areas for experiential learning and ecological research

    Science.gov (United States)

    Starry, O.

    2005-05-01

    The Urban Ecology Institute (UEI) promotes the stewardship of healthy urban ecosystems by improving science and civic education for middle and high school youth and by working with urban communities to protect and transform natural resources. Established in 1999, UEI's field studies program engages over 1000 youth in the greater Boston area. A substantial component of this program involves water quality monitoring. We have recently adapted protocols from published leaf breakdown studies for incorporation into the UEI water quality curriculum. A 2004 pilot study of these leaf breakdown activities, conducted at four sites, compared rates of red maple breakdown to those of Norway maple, a potentially invasive urban street tree. Preliminary data from this successful pilot study suggest that leaf litter inputs from the two different tree species have varying effects on stream ecosystem function. We present this study as an example of how urban areas can be utilized for both ecological research and inclusive experiential learning through which science and mathematic knowledge can be effectively communicated.

  10. Film dosimetry in conformal radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Danciu, C.; Proimos, B.S. [Patras Univ. (Greece). Dept. of Medical Physics

    1995-12-01

    Dosimetry, through a film sandwiched in a transverse cross-section of a solid phantom, is a method of choice in Conformal Radiotherapy because: (a) the blackness (density) of the film at each point offers a measure of the total dose received at that point, and (b) the film is easily calibrated by exposing a film strip in the same cross-section, through a stationary field. The film must therefore have the following properties: (a) it must be slow, in order not to be overexposed, even at a therapeutic dose of 200 cGy, and (b) the response of the film (density versus dose curve) must be independent of the photon energy spectrum. A few slow films were compared. It was found that the Kodak X-Omat V for therapy verification was the best choice. To investigate whether the film response was independent of the photon energy, response curves for six depths, starting from the depth of maximum dose to the depth of 25 cm, in solid phantom were derived. The vertical beam was perpendicular to the anterior surface of the phantom, which was at the distance of 100 cm from the source and the field was 15x15 cm at that distance. This procedure was repeated for photon beams emitted by a Cobalt-60 unit, two 6 MV and 15 MV Linear Accelerators, as well as a 45 MV Betatron. For each of those four different beams the film response was the same for all six depths. The results, as shown in the diagrams, are very satisfactory. The response curve under a geometry similar to that actually applied, when the film is irradiated in a transverse cross-section of the phantom, was derived. The horizontal beam was almost parallel (angle of 85) to the plane of the film. The same was repeated with the central ray parallel to the film (angle 90) and at a distance of 1.5 cm from the horizontal film. The field size was again 15x15 at the lateral entrance surface of the beam. The response curves remained the same, as when the beam was perpendicular to the films.

  11. Dose Verification of Stereotactic Radiosurgery Treatment for Trigeminal Neuralgia with Presage 3D Dosimetry System

    OpenAIRE

    2010-01-01

    Achieving adequate verification and quality-assurance (QA) for radiosurgery treatment of trigeminal-neuralgia (TGN) is particularly challenging because of the combination of very small fields, very high doses, and complex irradiation geometries (multiple gantry and couch combinations). TGN treatments have extreme requirements for dosimetry tools and QA techniques, to ensure adequate verification. In this work we evaluate the potential of Presage/Optical-CT dosimetry system as a tool for the v...

  12. Eleventh DOE workshop on personnel neutron dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-31

    Since its formation, the Office of Health (EH-40) has stressed the importance of the exchange of information related to and improvements in neutron dosimetry. This Workshop was the eleventh in the series sponsored by the Department of Energy (DOE). It provided a forum for operational personnel at DOE facilities to discuss current issues related to neutron dosimetry and for leading investigators in the field to discuss promising approaches for future research. A total of 26 papers were presented including the keynote address by Dr. Warren K. Sinclair, who spoke on, ``The 1990 Recommendations of the ICRP and their Biological Background.`` The first several papers discussed difficulties in measuring neutrons of different energies and ways of compensating or deriving correction factors at individual facilities. Presentations were also given by the US Navy and Air Force. Current research in neutron dosimeter development was the subject of the largest number of papers. These included a number on the development of neutron spectrometers. Selected papers were processed separately for inclusion in the Energy Science and Technology Database.

  13. The intellectual structure and substance of the knowledge utilization field: A longitudinal author co-citation analysis, 1945 to 2004

    Science.gov (United States)

    Estabrooks, Carole A; Derksen, Linda; Winther, Connie; Lavis, John N; Scott, Shannon D; Wallin, Lars; Profetto-McGrath, Joanne

    2008-01-01

    Background It has been argued that science and society are in the midst of a far-reaching renegotiation of the social contract between science and society, with society becoming a far more active partner in the creation of knowledge. On the one hand, new forms of knowledge production are emerging, and on the other, both science and society are experiencing a rapid acceleration in new forms of knowledge utilization. Concomitantly since the Second World War, the science underpinning the knowledge utilization field has had exponential growth. Few in-depth examinations of this field exist, and no comprehensive analyses have used bibliometric methods. Methods Using bibliometric analysis, specifically first author co-citation analysis, our group undertook a domain analysis of the knowledge utilization field, tracing its historical development between 1945 and 2004. Our purposes were to map the historical development of knowledge utilization as a field, and to identify the changing intellectual structure of its scientific domains. We analyzed more than 5,000 articles using citation data drawn from the Web of Science®. Search terms were combinations of knowledge, research, evidence, guidelines, ideas, science, innovation, technology, information theory and use, utilization, and uptake. Results We provide an overview of the intellectual structure and how it changed over six decades. The field does not become large enough to represent with a co-citation map until the mid-1960s. Our findings demonstrate vigorous growth from the mid-1960s through 2004, as well as the emergence of specialized domains reflecting distinct collectives of intellectual activity and thought. Until the mid-1980s, the major domains were focused on innovation diffusion, technology transfer, and knowledge utilization. Beginning slowly in the mid-1980s and then growing rapidly, a fourth scientific domain, evidence-based medicine, emerged. The field is dominated in all decades by one individual, Everett

  14. The intellectual structure and substance of the knowledge utilization field: A longitudinal author co-citation analysis, 1945 to 2004

    Directory of Open Access Journals (Sweden)

    Wallin Lars

    2008-11-01

    Full Text Available Abstract Background It has been argued that science and society are in the midst of a far-reaching renegotiation of the social contract between science and society, with society becoming a far more active partner in the creation of knowledge. On the one hand, new forms of knowledge production are emerging, and on the other, both science and society are experiencing a rapid acceleration in new forms of knowledge utilization. Concomitantly since the Second World War, the science underpinning the knowledge utilization field has had exponential growth. Few in-depth examinations of this field exist, and no comprehensive analyses have used bibliometric methods. Methods Using bibliometric analysis, specifically first author co-citation analysis, our group undertook a domain analysis of the knowledge utilization field, tracing its historical development between 1945 and 2004. Our purposes were to map the historical development of knowledge utilization as a field, and to identify the changing intellectual structure of its scientific domains. We analyzed more than 5,000 articles using citation data drawn from the Web of Science®. Search terms were combinations of knowledge, research, evidence, guidelines, ideas, science, innovation, technology, information theory and use, utilization, and uptake. Results We provide an overview of the intellectual structure and how it changed over six decades. The field does not become large enough to represent with a co-citation map until the mid-1960s. Our findings demonstrate vigorous growth from the mid-1960s through 2004, as well as the emergence of specialized domains reflecting distinct collectives of intellectual activity and thought. Until the mid-1980s, the major domains were focused on innovation diffusion, technology transfer, and knowledge utilization. Beginning slowly in the mid-1980s and then growing rapidly, a fourth scientific domain, evidence-based medicine, emerged. The field is dominated in all decades

  15. The intellectual structure and substance of the knowledge utilization field: a longitudinal author co-citation analysis, 1945 to 2004.

    Science.gov (United States)

    Estabrooks, Carole A; Derksen, Linda; Winther, Connie; Lavis, John N; Scott, Shannon D; Wallin, Lars; Profetto-McGrath, Joanne

    2008-11-13

    It has been argued that science and society are in the midst of a far-reaching renegotiation of the social contract between science and society, with society becoming a far more active partner in the creation of knowledge. On the one hand, new forms of knowledge production are emerging, and on the other, both science and society are experiencing a rapid acceleration in new forms of knowledge utilization. Concomitantly since the Second World War, the science underpinning the knowledge utilization field has had exponential growth. Few in-depth examinations of this field exist, and no comprehensive analyses have used bibliometric methods. Using bibliometric analysis, specifically first author co-citation analysis, our group undertook a domain analysis of the knowledge utilization field, tracing its historical development between 1945 and 2004. Our purposes were to map the historical development of knowledge utilization as a field, and to identify the changing intellectual structure of its scientific domains. We analyzed more than 5,000 articles using citation data drawn from the Web of Science. Search terms were combinations of knowledge, research, evidence, guidelines, ideas, science, innovation, technology, information theory and use, utilization, and uptake. We provide an overview of the intellectual structure and how it changed over six decades. The field does not become large enough to represent with a co-citation map until the mid-1960s. Our findings demonstrate vigorous growth from the mid-1960s through 2004, as well as the emergence of specialized domains reflecting distinct collectives of intellectual activity and thought. Until the mid-1980s, the major domains were focused on innovation diffusion, technology transfer, and knowledge utilization. Beginning slowly in the mid-1980s and then growing rapidly, a fourth scientific domain, evidence-based medicine, emerged. The field is dominated in all decades by one individual, Everett Rogers, and by one paradigm

  16. Monte Carlo simulations to optimize experimental dosimetry of narrow beams used in Gamma Knife radio-surgery

    Energy Technology Data Exchange (ETDEWEB)

    Lymperopoulou, G. [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece)], E-mail: glymper@phys.uoa.gr; Petrokokkinos, L.; Papagiannis, P. [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Steiner, M.; Spevacek, V.; Semnicka, J.; Dvorak, P. [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Department of Dosimetry and Application of Ionizing Radiation, Brehova 7 115 19, Prague 1 (Czech Republic); Seimenis, I. [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece)

    2007-09-21

    The Leksell Gamma Knife is a stereotactic radio-surgery unit for the treatment of small volumes (on the order of 25 mm{sup 3}) that employs a hemispherical configuration of 201 {sup 60}Co sources and appropriate configurations of collimation to form beams of 4, 8, 14 and 18 mm nominal diameter at the Unit Center Point (UCP). Although Monte Carlo (MC) simulation is well suited for narrow-beam dosimetry, experimental dosimetry is required at least for acceptance testing and quality assurance purposes. Besides other drawbacks of conventional point dosimeters, the main problems associated with narrow-beam dosimetry in stereotactic applications are accurate positioning and volume averaging. In this work, MCNPX and EGSnrc MC simulation dosimetry results for a Gamma Knife unit are benchmarked through their comparison to treatment planning software calculations based on radio-chromic film measurements. Then, MC dosimetry results are utilized to optimize the only three-dimensional experimental dosimetry method available; the polymer gel-Magnetic Resonance Imaging (MRI) method. MC results are used to select the spatial resolution in the imaging session of the irradiated gels and validate a mathematical tool for the localization of the UCP in the three-dimensional experimental dosimetry data acquired. Experimental results are compared with corresponding MC calculations and shown capable to provide accurate dosimetry, free of volume averaging and positioning uncertainties.

  17. Dosimetry for Electron Beam Applications

    DEFF Research Database (Denmark)

    Miller, Arne

    1983-01-01

    This report describes two aspects of electron bean dosimetry, on one hand developaent of thin fil« dosimeters and measurements of their properties, and on the other hand developaent of calorimeters for calibration of routine dosimeters, e.g. thin films. Two types of radiochromic thin film...

  18. In aqua vivo EPID dosimetry

    NARCIS (Netherlands)

    Wendling, M.; McDermott, L.N.; Mans, A.; Olaciregui-Ruiz, I.; Pecharroman-Gallego, R.; Sonke, J.J.; Stroom, J.; Herk, M. van; Mijnheer, B.J.

    2012-01-01

    PURPOSE: At the Netherlands Cancer Institute--Antoni van Leeuwenhoek Hospital in vivo dosimetry using an electronic portal imaging device (EPID) has been implemented for almost all high-energy photon treatments of cancer with curative intent. Lung cancer treatments were initially excluded, because t

  19. In vivo dosimetry in brachytherapy

    DEFF Research Database (Denmark)

    Tanderup, Kari; Beddar, Sam; Andersen, Claus Erik;

    2013-01-01

    In vivo dosimetry (IVD) has been used in brachytherapy (BT) for decades with a number of different detectors and measurement technologies. However, IVD in BT has been subject to certain difficulties and complexities, in particular due to challenges of the high-gradient BT dose distribution and th...

  20. Portal dosimetry in wedged beams

    NARCIS (Netherlands)

    Spreeuw, H.; Rozendaal, R.; Camargo, P.; Mans, A.; Wendling, M.; Olaciregui-Ruiz, I.; Sonke, J.J.; Herk, M. van; Mijnheer, B.

    2015-01-01

    Portal dosimetry using electronic portal imaging devices (EPIDs) is often applied to verify high-energy photon beam treatments. Due to the change in photon energy spectrum, the resulting dose values are, however, not very accurate in the case of wedged beams if the pixel-to-dose conversion for the s

  1. Generalized EPID calibration for in vivo transit dosimetry.

    Science.gov (United States)

    Fidanzio, Andrea; Cilla, Savino; Greco, Francesca; Gargiulo, Laura; Azario, Luigi; Sabatino, Domenico; Piermattei, Angelo

    2011-01-01

    Many researchers are studying new in vivo dosimetry methods based on the use of Elelctronic portal imaging devices (EPIDs) that are simple and efficient in their daily use. However the need of time consuming implementation measurements with solid water phantoms for the in vivo dosimetry implementation can discourage someone in their use. In this paper a procedure has been proposed to calibrate aSi EPIDs for in vivo transit dosimetry. The dosimetric equivalence of three aSi Varian EPIDs has been investigated in terms of signal reproducibility and long term stability, signal linearity with MU and dose per pulse and signal dependence on the field dimensions. The signal reproducibility was within ± 0.5% (2SD), while the long term signal stability has been maintained well within ± 2%. The signal linearity with the monitor units (MU) was within ± 2% and within ± 0.5% for the EPIDs controlled by the IAS 2, and IAS 3 respectively. In particular it was verified that the correction factor for the signal linearity with the monitor units, k(lin), is independent of the beam quality, and the dose per pulse absorbed by the EPID. For 6, 10 and 15 MV photon beams, a generalized set of correlation functions F(TPR,w,L) and empirical factors f(TPR,d,L) as a function of the Tissue Phantom Ratio (TPR), the phantom thickness, w, the square field side, L, and the distance, d, between the phantom mid-plane and the isocentre were determined to reconstruct the isocenter dose. The tolerance levels of the present in vivo dosimetry method ranged between ± 5% and ± 6% depending on the tumor body location. In conclusion, the procedure proposed, that use generalized correlation functions, reduces the effort for the in vivo dosimetry method implementation for those photon beams with TPR within ± 0.3% as respect those here used.

  2. Quality control for X-ray dosimetry with Fricke dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Vivianne Lucia Bormann de [Centro Regional de Cincias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)]. E-mail: lsouza@cnen.gov.br; Austerlitz, C. [East Carolina University, NC (United States)]. E-mail: camposc@ecu.edu

    2007-07-01

    It is a well-established fact that the success of radiation therapy is dependent on the accurate dosimetry of the radiation beam used. This dosimetry must include equipment performance as well. A system for Fricke dosimetry was used for this purpose. The Fricke solution and a parallel ionization chamber (used for comparison) were irradiated with an X-ray beam from a Pantak X-ray equipment. The ionization chamber was positioned at a distance of 500 mm of the focal point, in the central axis of the X-ray field which is defined as 100x100 mm{sup 2} at the calibration distance. A plexiglas phantom appropriate to hold the polypropylene tube was used to irradiate the vials with the Fricke solution. The irradiated solutions were transferred directly from the polypropylene vials to 10 mm length cuvettes and the optical densities were measured in 304 nm using a Beckman Counter Model DU 640 spectrophotometer. Three institutions were visited to verify their procedures and two were in accordance with the lAEA recommended procedures for soft X-ray dosimetry. The results of the measurements performed in the institutions visited show that the Fricke dosimeter system developed can be used for quality control for soft X-ray equipment. (author)

  3. The Utility Frequence of The Devices with Electromagnetic Field By Nurses.

    Directory of Open Access Journals (Sweden)

    Aysegul Akar

    2010-12-01

    Full Text Available AIM: The electromagnetic waves (EMW emitted by both natural and man made sources have increased in our daily surroundings and the threat presented by these waves is crucial for human health. The aim of this study was determine the utility frequence of the devices with electromagnetic field by the nurses deployed in Ondokuz Mayis University Hospital (OMUH. METHOD: This cross-sectional study was conducted between 1and 31May 2009 at OMUH. Of the 456 nurses who worked at the hospital in this period, 368 (80.7% nurses accepted to participate in our study. The data are presented as medians (minimum-maximum and percentages. The data were evaluated using Mann-Whitney U test and the level of statistical significance was determined as p<0.05. RESULTS: Of all the participants, 366 (99.5% used mobile telephone, 293 (79.6% used hair dryer, 289 (78.6% used satellite receiver, 129 (35.1% used wireless internet modem and 73 (19.8% used microwave oven. Of the nurses using mobile telephone, 102 nurses (27.9% had “limitless talk” tariff. There was no statistical difference with respect to the minimum amount of time allocated to the telephone talk and monthly expenditure between nurses using the limitless talk tariff and those who did not. On the other hand, there was difference in the maximum amount of time allocated to the telephone talk (p<0.05. Of these nurses, 311 (85% reported that they left their mobile telephones on at night and the mobile telephone was kept at bedroom by almost all of these subjects. Sixty six participants (18% reported that they used mobile telephone while driving. CONCLUSION: Our study revealed that almost all the participants used EMW emitting devices and that mobile telephone was the most common EMW emitting device. As it is not possible to completely remove the EMW emitting devices from our lives, we believe that their utility should be limited to minimize their negative effects. [TAF Prev Med Bull 2010; 9(6.000: 579-584

  4. Plutonium worker dosimetry.

    Science.gov (United States)

    Birchall, Alan; Puncher, M; Harrison, J; Riddell, A; Bailey, M R; Khokryakov, V; Romanov, S

    2010-05-01

    Epidemiological studies of the relationship between risk and internal exposure to plutonium are clearly reliant on the dose estimates used. The International Commission on Radiological Protection (ICRP) is currently reviewing the latest scientific information available on biokinetic models and dosimetry, and it is likely that a number of changes to the existing models will be recommended. The effect of certain changes, particularly to the ICRP model of the respiratory tract, has been investigated for inhaled forms of (239)Pu and uncertainties have also been assessed. Notable effects of possible changes to respiratory tract model assumptions are (1) a reduction in the absorbed dose to target cells in the airways, if changes under consideration are made to the slow clearing fraction and (2) a doubling of absorbed dose to the alveolar region for insoluble forms, if evidence of longer retention times is taken into account. An important factor influencing doses for moderately soluble forms of (239)Pu is the extent of binding of dissolved plutonium to lung tissues and assumptions regarding the extent of binding in the airways. Uncertainty analyses have been performed with prior distributions chosen for application in epidemiological studies. The resulting distributions for dose per unit intake were lognormal with geometric standard deviations of 2.3 and 2.6 for nitrates and oxides, respectively. The wide ranges were due largely to consideration of results for a range of experimental data for the solubility of different forms of nitrate and oxides. The medians of these distributions were a factor of three times higher than calculated using current default ICRP parameter values. For nitrates, this was due to the assumption of a bound fraction, and for oxides due mainly to the assumption of slower alveolar clearance. This study highlights areas where more research is needed to reduce biokinetic uncertainties, including more accurate determination of particle transport rates

  5. ESR dosimetry: achievements and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Baffa, O., E-mail: baffa@usp.br [Universidade de Sao Paulo, Departamento de Fisica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    2015-10-15

    Full text: Electron Spin Resonance (ESR), also known as Electron Paramagnetic Resonance (EPR) and more recently as Electron Magnetic Resonance (Emr), is a spectroscopy technique able to detect unpaired electrons such as those created by the interaction ionizing radiation with matter. When the unpaired electrons created by ionizing radiation are stable over some reasonable time, ESR can be used to measure the radiation dose deposited in the material under study. In principle, any insulating material that satisfies this requisite can be used as a dosimeter. ESR has been used in retrospective dosimetry in case of radiological accidents using natural constituents of human body such as teeth, bones and nails as well as fortuitous materials as sugar, sweeteners and plastics. When using teeth the typical detected dose is 0.5 Gy for, for X-Band spectrometers (9 GHz) and even lower doses if higher frequency spectrometers are used. Clinical dosimetry is another area of potential use of this dosimetric modality. In this application the amino acid alanine has been proposed and being used. Alanine dosimeters are very easy to prepare and require no complicated treatments for use. Alanine/ESR dosimetry satisfies many of the required properties for clinical applications such as water equivalent composition, independence of response for the energy range used in therapy and high precision. Other organic materials such as ammonium tartrate are being investigated to increase the sensitivity of ESR for clinical applications. Finally, industrial applications can also benefit from this dosimetry. The challenges to expand applications, the number of users and research groups of ESR dosimetry will be discussed. (Author)

  6. Utilization of Red Mud as Raw Material in the Production of Field Road Cement

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao; LUO Zhongtao; ZHANG Lei; RONG Hui; YANG Jiujun

    2016-01-01

    The total utilization amount of red mud is limited due to its high content of alkali, heavy metals and naturally occurring radioactive element. In order to rationalize the use of red mud, a typical ifeld road cement using dealkalized red mud (content of alkali lower than 1%) as raw material was ifrstly prepared in this paper. Then, a preliminary research on the radioactivity of the red mud based ifeld road cement has been carried out. For that reason, two samples of raw materials were prepared. One was with ordinary raw materials, as the control group (CG), the other was with 23w % red mud, as the experimental group (EG). The clinkers were acquired by sintering the above two raw materials at 1 400℃. Subsequently, the two types of cement prepared by the above two kinds of clinkers were tested by measuring the normal consistency, setting time, mechanical strength and drying shrinkage. Meanwhile, the hydration products of the two types of cement were examined by XRD analysis at the curing age of 6 hours, 1, 3, 7, and 28 days, respectively. The radioactivity of the two kinds of cement clinkers was then measured by gamma-ray spectrometry. The experimental results indicate that the main mineralogical phases components in the EG ifeld road cement clinkers are C3S, C2S, and C4AF, the 28 days lfexural and compressive strength of the EG ifeld road cement mortars could be up to 8.45 and 53.2 MPa, respectively. The radioactive measuring results of the EG field road cement show that the value of radium equivalent activity index (Raeq) is 254.8 Bq/Kg-1, which is lower than the upper limit.

  7. Dosimetry of low-energy beta radiation

    Energy Technology Data Exchange (ETDEWEB)

    Borg, J.

    1996-08-01

    Useful techniques and procedures for determination of absorbed doses from exposure in a low-energy {beta} radiation field were studied and evaluated in this project. The four different techniques included were {beta} spectrometry, extrapolation chamber dosimetry, Monte Carlo (MC) calculations, and exoelectron dosimetry. As a typical low-energy {beta} radiation field a moderated spectrum from a {sup 14}C source (E{sub {beta}},{sub max} =156 keV) was chosen for the study. The measured response of a Si(Li) detector to photons (bremsstrahlung) showed fine agreement with the MC calculated photon response, whereas the difference between measured and MC calculated responses to electrons indicates an additional dead layer thickness of about 12 {mu}m in the Si(Li) detector. The depth-dose profiles measured with extrapolation chambers at two laboratories agreed very well, and it was confirmed that the fitting procedure previously reported for {sup 147}Pm depth-dose profiles is also suitable for {beta} radiation from {sup 14}C. An increasing difference between measured and MC calculated dose rates for increasing absorber thickness was found, which is explained by limitations of the EGS4 code for transport of very low-energy electrons (below 10-20 keV). Finally a study of the thermally stimulated exoelectron emission (TSEE) response of BeO thin film dosemeters to {beta} radiation for radiation fields with maximum {beta} energies ranging from 67 keV to 2.27 MeV is reported. For maximum {beta} energies below approximately 500 keV, a decrease in the response amounting to about 20% was observed. It is thus concluded that a {beta} dose higher than about 10 {mu}Gy can be measured with these dosemeters to within 0 to -20% independently of the {beta}energy for E{sub {beta}},{sub max} values down to 67 keV. (au) 12 tabs., 38 ills., 71 refs.

  8. Feasibility of portal dosimetry for flattening filter-free radiotherapy.

    Science.gov (United States)

    Chuter, Robert W; Rixham, Philip A; Weston, Steve J; Cosgrove, Vivian P

    2016-01-08

    The feasibility of using portal dosimetry (PD) to verify 6 MV flattening filter-free (FFF) IMRT treatments was investigated. An Elekta Synergy linear accelerator with an Agility collimator capable of delivering FFF beams and a standard iViewGT amorphous silicon (aSi) EPID panel (RID 1640 AL5P) at a fixed SSD of 160 cm were used. Dose rates for FFF beams are up to four times higher than for conventional flattened beams, meaning images taken at maximum FFF dose rate can saturate the EPID. A dose rate of 800 MU/min was found not to saturate the EPID for open fields. This dose rate was subsequently used to characterize the EPID for FFF portal dosimetry. A range of open and phantom fields were measured with both an ion chamber and the EPID, to allow comparison between the two. The measured data were then used to create a model within The Nederlands Kanker Instituut's (NKI's) portal dosimetry software. The model was verified using simple square fields with a range of field sizes and phantom thicknesses. These were compared to calculations performed with the Monaco treatment planning system (TPS) and isocentric ion chamber measurements. It was found that the results for the FFF verification were similar to those for flattened beams with testing on square fields, indicating a difference in dose between the TPS and portal dosimetry of approximately 1%. Two FFF IMRT plans (prostate and lung SABR) were delivered to a homogeneous phantom and showed an overall dose difference at isocenter of ~0.5% and good agreement between the TPS and PD dose distributions. The feasibility of using the NKI software without any modifications for high-dose-rate FFF beams and using a standard EPID detector has been investigated and some initial limitations highlighted.

  9. Sample size requirements for estimating effective dose from computed tomography using solid-state metal-oxide-semiconductor field-effect transistor dosimetry

    Science.gov (United States)

    Trattner, Sigal; Cheng, Bin; Pieniazek, Radoslaw L.; Hoffmann, Udo; Douglas, Pamela S.; Einstein, Andrew J.

    2014-01-01

    Purpose: Effective dose (ED) is a widely used metric for comparing ionizing radiation burden between different imaging modalities, scanners, and scan protocols. In computed tomography (CT), ED can be estimated by performing scans on an anthropomorphic phantom in which metal-oxide-semiconductor field-effect transistor (MOSFET) solid-state dosimeters have been placed to enable organ dose measurements. Here a statistical framework is established to determine the sample size (number of scans) needed for estimating ED to a desired precision and confidence, for a particular scanner and scan protocol, subject to practical limitations. Methods: The statistical scheme involves solving equations which minimize the sample size required for estimating ED to desired precision and confidence. It is subject to a constrained variation of the estimated ED and solved using the Lagrange multiplier method. The scheme incorporates measurement variation introduced both by MOSFET calibration, and by variation in MOSFET readings between repeated CT scans. Sample size requirements are illustrated on cardiac, chest, and abdomen–pelvis CT scans performed on a 320-row scanner and chest CT performed on a 16-row scanner. Results: Sample sizes for estimating ED vary considerably between scanners and protocols. Sample size increases as the required precision or confidence is higher and also as the anticipated ED is lower. For example, for a helical chest protocol, for 95% confidence and 5% precision for the ED, 30 measurements are required on the 320-row scanner and 11 on the 16-row scanner when the anticipated ED is 4 mSv; these sample sizes are 5 and 2, respectively, when the anticipated ED is 10 mSv. Conclusions: Applying the suggested scheme, it was found that even at modest sample sizes, it is feasible to estimate ED with high precision and a high degree of confidence. As CT technology develops enabling ED to be lowered, more MOSFET measurements are needed to estimate ED with the same

  10. EPR/PTFE dosimetry for test reactor environments

    Energy Technology Data Exchange (ETDEWEB)

    Vehar, D.W.; Griffin, P.J.; Quirk, T.J. [Sandia National Laboratories, Albuquerque, NM 87185-1146 (United States)

    2011-07-01

    The use of Electron Paramagnetic Resonance (EPR) spectroscopy with materials such as alanine is well established as a technique for measurement of ionizing radiation absorbed dose in photon and electron fields such as Co-60, high-energy bremsstrahlung and electron-beam fields [1]. In fact, EPR/Alanine dosimetry has become a routine transfer standard for national standards bodies such as NIST and NPL. In 1992 the Radiation Metrology Laboratory (RML) at Sandia National Laboratories implemented EPR/Alanine capabilities for use in routine and calibration activities at its Co-60 and pulsed-power facilities. At that time it also investigated the usefulness of the system for measurement of absorbed dose in the mixed neutron/photon environments of reactors such as the Sandia Pulsed Reactor and the Annular Core Research Reactor used for hardness testing of electronics. The RML concluded that the neutron response of alanine was a sufficiently high fraction of the overall dosimeter response that the resulting uncertainties in the photon dose would be unacceptably large for silicon-device testing. However, it also suggested that non-hydrogenous materials such as polytetrafluoroethylene (PTFE) would exhibit smaller neutron response and might be useful in mixed environments. Preliminary research with PTFE in photon environments indicated considerable promise, but further development was not pursued at that time. Because of renewed interest in absorbed dose measurements that could better define the individual contributions of photon and neutron components to the overall dose delivered to a test object, the RML has re-initiated the development of an EPR/PTFE dosimetry system. This effort consists of three stages: 1) Identification of PTFE materials that may be suitable for dosimetry applications. It was speculated that the inconsistency of EPR signatures in the earlier samples may have been due to variability in PTFE manufacturing processes. 2) Characterization of dosimetry in

  11. Developing a science of clinical utility in diagnostic classification systems field study strategies for ICD-11 mental and behavioral disorders.

    Science.gov (United States)

    Keeley, Jared W; Reed, Geoffrey M; Roberts, Michael C; Evans, Spencer C; Medina-Mora, María Elena; Robles, Rebeca; Rebello, Tahilia; Sharan, Pratap; Gureje, Oye; First, Michael B; Andrews, Howard F; Ayuso-Mateos, José Luís; Gaebel, Wolfgang; Zielasek, Juergen; Saxena, Shekhar

    2016-01-01

    The World Health Organization (WHO) Department of Mental Health and Substance Abuse has developed a systematic program of field studies to evaluate and improve the clinical utility of the proposed diagnostic guidelines for mental and behavioral disorders in the Eleventh Revision of the International Classification of Diseases and Related Health Problems (ICD-11). The clinical utility of a diagnostic classification is critical to its function as the interface between health encounters and health information, and to making the ICD-11 be a more effective tool for helping the WHO's 194 member countries, including the United States, reduce the global disease burden of mental disorders. This article describes the WHO's efforts to develop a science of clinical utility in regard to one of the two major classification systems for mental disorders. We present the rationale and methodologies for an integrated and complementary set of field study strategies, including large international surveys, formative field studies of the structure of clinicians' conceptualization of mental disorders, case-controlled field studies using experimental methodologies to evaluate the impact of proposed changes to the diagnostic guidelines on clinicians' diagnostic decision making, and ecological implementation field studies of clinical utility in the global settings in which the guidelines will ultimately be implemented. The results of these studies have already been used in making decisions about the structure and content of ICD-11. If clinical utility is indeed among the highest aims of diagnostic systems for mental disorders, as their developers routinely claim, future revision efforts should continue to build on these efforts. (PsycINFO Database Record

  12. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Fratin, Luciano

    1993-12-31

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

  13. Results from 2010 Caliban Criticality Dosimetry Intercomparison

    Energy Technology Data Exchange (ETDEWEB)

    Veinot, K. G.

    2011-10-12

    The external dosimetry program participated in a criticality dosimetry intercomparison conducted at the Caliban facility in Valduc, France in 2010. Representatives from the dosimetry and instrumentation groups were present during testing which included irradiations of whole-body beta/gamma (HBGT) and neutron thermoluminescent dosimeters (TLDs), a fixed nuclear accident dosimeter (FNAD), electronic alarming dosimeters, and a humanoid phantom filled with reference man concentrations of sodium. This report reviews the testing procedures, preparations, irradiations, and presents results of the tests.

  14. Latest developments in silica fibre luminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D. A.; Abdul S, S. F.; Jafari, S. M.; Alanazi, A. [University of Surrey, Department of Physics, GU2 7XH Guildford, Surrey (United Kingdom); Amouzad M, G. [University of Malaya, Faculty of Engineering, Department of Electrical Engineering, Integrated Lightwave Research Group, 50603 Kuala Lumpur (Malaysia); Addul R, H. A.; Mizanur R, A. K. M.; Zubair, H. T.; Begum, M.; Yusoff, Z.; Omar, N. Y. M. [Multimedia University, Faculty of Engineering, 2010 Cyberjaya, Selangor (Malaysia); Maah, M. J. [University of Malaya, Department of Chemistry, 50603 Kuala Lumpur (Malaysia); Collin, S. [National Physical Laboratory, Hampton Road, Teddington, TW11 OLW Middlesex (United Kingdom); Mat-Sharif, K. A.; Muhd-Yassin, S. Z.; Zulkifli, M. I., E-mail: d.a.bradley@surrey.ac.uk [Telekom Malaysia Research and Development Sdn Bhd., 63000 Cyberjaya, Selangor (Malaysia)

    2015-10-15

    Full text: Using tailor made sub-mm diameter doped-silica fibres, we are carrying out luminescence dosimetry studies for a range of situations, including thermoluminescence (Tl)investigations on a liquid alpha source formed of {sup 223}RaCl (the basis of the Bayer Health care product Xofigo), the Tl response to a 62 MeV proton source and Tl response to irradiation from an {sup 241}Am-Be neutron source. In regard to the former, in accord with the intrinsic high linear energy transfer (Let) and short path length (<100 um) of the α-particles in calcified tissue, the product is in part intended as a bone-seeking radionuclide for treatment of metastatic cancer, offering high specificity and efficacy. The Tl yield of Ge-doped SiO{sub 2} fibres has been investigated including for photonic crystal fibre un collapsed, flat fibres and single mode fibres, these systems offering many advantages over conventional passive dosimetry types. In particular, one can mention comparable and even superior sensitivity, an effective atomic number Z{sub eff} of the silica dosimetric material close to that of bone, and the glassy nature of the fibres offering the additional advantage of being able to place such dosimeters directly into liquid environments. Finally we review the use of our tailor made fibres for on-line radioluminescence measurements of radiotherapy beams. The outcome from these various lines of research is expected to inform development of doped fiber radiation dosimeters of versatile utility, ranging from clinical applications through to industrial studies and environmental evaluations. (Author)

  15. Performance of the CEDS Accident Dosimetry System at the 1995 Los Alamos National Laboratory Nuclear Accident Dosimetry Intercomparison

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, K.L.; Schwanke, L.J.

    1996-12-01

    In July 1995, LANL hosted an accident dosimetry intercomparison. When all reactors on the Oak Ridge Reservation were idled in 1988, the Health Physics Research Reactor (HPRR), which had been used for 22 previous intercomparisons dating from 1965, was shut down for an indefinite period. The LANL group began characterization of two critical assemblies for dosimetry purposes. As a result, NAD-23 was conceived and 10 DOE facilities accepted invitations to participate in the intercomparison. This report is a summary of the performance of one of the participants, the Centralized External Dosimetry System (CEDS). The CEDS is a cooperative personnel dosimetry arrangement between three DOE sites in Oak Ridge, Tennessee. Many successes and failures are reported herein. Generally, the TL dosimeters performed poorly and always over-reported the delivered dose. The TLD processing procedures contain efforts that would lead to large biases in the reported absorbed dose, and omit several key steps in the TLD reading process. The supralinear behavior of lithium fluoride (LiF) has not been characterized for this particular dosimeter and application (i.e., in high-dose mixed neutron/gamma fields). The use of TLD materials may also be precluded given the limitations of the LiF material itself, the TLD reading system, and the upper dose level to which accident dosimetry systems are required to perform as set forth in DOE regulations. The indium foil results confirm the expected inability of that material to predict the magnitude of the wearer`s dose reliably, although it is quite suitable as a quick-sort material. Biological sample (hair) results were above the minimum detectable activity (MDA) for only one of the tests. Several questions as to the best methods for sample handling and processing remain.

  16. MISTI Shielding and Dosimetry Experiment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reliable on-orbit dosimetry is necessary for understanding effects of space radiation environments on spacecraft microelectronics performance and comparison of...

  17. Utilizing High Resolution Panoramas as Virtual Field Experiences in Undergraduate Planetary Science Courses

    Science.gov (United States)

    Piatek, J. L.

    2011-03-01

    Tier-scalable exercises utilizing high resolution panoramas allow students to explore terrestrial landscapes and outcrops virtually, and provide good context for interpreting spacecraft images of solar system bodies.

  18. Fifth personnel dosimetry intercomparison study

    Energy Technology Data Exchange (ETDEWEB)

    Sims, C.S.

    1980-02-01

    The fifth Personnel Dosimetry Intercomparison Study (PDIS) was conducted at the Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research (DOSAR) facility on March 20-22, 1979. This study is the latest PDIS in the continuing series started at the DOSAR facility in 1974. The PDIS is a three day study, typically in March, where personnel dosimeters are mailed to the DOSAR facility, exposed to a range of low-level neutron radiation doses (1 to 15 mSv or equivalently, 100 to 1500 mrem) and neutron-to-gamma ratios (1:1-10:1) using the Health Physics Research Reactor (HPRR) as the radiation source, and returned to the participants for evaluation. This report is a summary and analysis of the results reported by the various participants. The participants are able to intercompare their results with those of others who made dose measurements under identical experimental conditions.

  19. NOTE FROM THE DOSIMETRY SERVICE

    CERN Multimedia

    2002-01-01

    During March, the Dosimetry Service will be opened from 8h30 to 12h in the morning and closed every afternoon.   We have established that many people, who are provided regularly with a personal dosimeter (film badge), have changed their activity and do not need it anymore, because they do not, or only exceptionally, enter controlled areas. If you are one of these persons, please contact the Personal Dosimeter Service (tel: 72155). There is a simplified procedure for obtaining a dosimeter if you have an immediate need for short-term visits in controlled areas. A reduction of the number of persons on the regular distribution list of dosimeters would decrease our and the distributors workload. It would also contribute to significant savings in the dosimetry, and thus CERN, budget. We thank you in advance for your understanding and for your collaboration.

  20. Dosimetry with phantom for total body irradiation (TBI)

    Energy Technology Data Exchange (ETDEWEB)

    Tezuka, Takako; Sakakura, Noriyuki; Obata, Yasunori; Tabushi, Katuyoshi; Kondou, Satoru [Nagoya Univ. (Japan). School of Health Sciences; Koyama, Syuuji; Aoyama, Yuuichi; Shimohira, Akiyo [Nagoya Univ. (Japan). Hospital

    2002-04-01

    Total body irradiation (TBI) is being used as a method of preparation for bone marrow transplantation (BMT). In TBI, the dose calculation is based on dosimetry using a phantom. We measured the basic dose with a phantom using a 10 MV X-rays. We confirmed the accuracy of the dose calculation performed in our facilities and investigated a method of more accurate dosimetry. We measured the variation in dose according to the size of the phantom and the depth using a tough water phantom, and examined the difference in TMR according to SCD, field size, and size of the phantom. Consequently, the dose has been changed regardless of the size of the phantom at larger than 80 x 30 x 30 cm{sup 3}, and it is about 1% larger than 30 x 30 x 30 cm{sup 3}. Also TMR has changed according to various conditions, including the size of the phantom, field size, and SCD. Therefore, it was found that dosimetry using the 30 x 30 x 30 cm{sup 3} phantom leads to underestimation in dose calculation, and there is no difference in dose between the field size of 151.5 x 160 cm{sup 2} and 151.5 x 80 cm{sup 2}. It is also necessary to consider the effect of the vertical size of the phantom. (author)

  1. Dosimetry for the external radiation therapy. Dosimetry with alanine; Dosimetrie fuer die externe Strahlentherapie. Dosimetrie mit Alanin

    Energy Technology Data Exchange (ETDEWEB)

    Anton, Mathias [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Arbeitsgruppe ' Alanin-Dosimetrie'

    2013-06-15

    The alanine-ESR dosimetry in the PTB is described. The response power of alanine related to the water energy dose for X-rays with average energy of 10-1000 keV is presented. Furthermore the application of alanine for the quality assurance in the radiation therapy is described by means of the prostate irradiation and the therapy of a tumor in the neck region as examples. (HSI)

  2. I-124 Imaging and Dosimetry

    Directory of Open Access Journals (Sweden)

    Russ Kuker

    2017-02-01

    Full Text Available Although radioactive iodine imaging and therapy are one of the earliest applications of theranostics, there still remain a number of unresolved clinical questions as to the optimization of diagnostic techniques and dosimetry protocols. I-124 as a positron emission tomography (PET radiotracer has the potential to improve the current clinical practice in the diagnosis and treatment of differentiated thyroid cancer. The higher sensitivity and spatial resolution of PET/computed tomography (CT compared to standard gamma scintigraphy can aid in the detection of recurrent or metastatic disease and provide more accurate measurements of metabolic tumor volumes. However the complex decay schema of I-124 poses challenges to quantitative PET imaging. More prospective studies are needed to define optimal dosimetry protocols and to improve patient-specific treatment planning strategies, taking into account not only the absorbed dose to tumors but also methods to avoid toxicity to normal organs. A historical perspective of I-124 imaging and dosimetry as well as future concepts are discussed.

  3. Dosimetry studies in Zaborie village.

    Science.gov (United States)

    Takada, J; Hoshi, M; Endo, S; Stepanenko, V F; Kondrashov, A E; Petin, D; Skvortsov, V; Ivannikov, A; Tikounov, D; Gavrilin, Y; Snykov, V P

    2000-05-01

    Dosimetry studies in Zaborie, a territory in Russia highly contaminated by the Chernobyl accident, were carried out in July, 1997. Studies on dosimetry for people are important not only for epidemiology but also for recovery of local social activity. The local contamination of the soil was measured to be 1.5-6.3 MBq/m2 of Cs-137 with 0.7-4 microSv/h of dose rate. A case study for a villager presently 40 years old indicates estimations of 72 and 269 mSv as the expected internal and external doses during 50 years starting in 1997 based on data of a whole-body measurement of Cs-137 and environmental dose rates. Mean values of accumulated external and internal doses for the period from the year 1986 till 1996 are also estimated to be 130 mSv and 16 mSv for Zaborie. The estimation of the 1986-1996 accumulated dose on the basis of large scale ESR teeth enamel dosimetry provides for this village, the value of 180 mSv. For a short term visitor from Japan to this area, external and internal dose are estimated to be 0.13 mSv/9d (during visit in 1997) and 0.024 mSv/50y (during 50 years starting from 1997), respectively.

  4. Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

    Energy Technology Data Exchange (ETDEWEB)

    Kerkhof, L.; Williams, K.H.; Long, P.E.; McGuinness, L.

    2011-02-21

    Previous experiments at the Rifle, Colorado Integrated Field Research Challenge (IFRC) site demonstrated that field-scale addition of acetate to groundwater reduced the ambient soluble uranium concentration. In this report, sediment samples collected before and after acetate field addition were used to assess the active microbes via {sup 13}C acetate stable isotope probing on 3 phases [coarse sand, fines (8-approximately 150 {micro}m), groundwater (0.2-8 {micro}m)] over a 24-day time frame. TRFLP results generally indicated a stronger signal in {sup 13}C-DNA in the 'fines' fraction compared to the sand and groundwater. Before the field-scale acetate addition, a Geobacter-like group primarily synthesized {sup 13}C-DNA in the groundwater phase, an alpha Proteobacterium primarily grew on the fines/sands, and an Acinetobacter sp. and Decholoromonas-like OTU utilized much of the {sup 13}C acetate in both groundwater and particle-associated phases. At the termination of the field-scale acetate addition, the Geobacter-like species was active on the solid phases rather than the groundwater, while the other bacterial groups had very reduced newly synthesized DNA signal. These findings will help to delineate the acetate utilization patterns of bacteria in the field and can lead to improved methods for stimulating distinct microbial populations in situ.

  5. JENDL dosimetry file 99 (JENDL/D-99)

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Katsuhei [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Institute; Iguchi, Tetsuo [Nagoya Univ., Faculty of Engineering, Nagoya, Aichi (Japan); Iwasaki, Shin [Tohoku Univ., Faculty of Engineering, Sendai, Miyagi (JP)] [and others

    2002-01-01

    The JENDL Dosimetry File 99 (JENDL/D-99), which is a revised version of the JENDL Dosimetry File 91 (JENDL/D-91), has been compiled and released for the determination of neutron flux and energy spectra. This work was undertaken to remove the inconsistency between the cross sections and their covariances in JENDL/D-91 since the covariances were mainly taken from IRDF-85 although the cross sections were based on JENDL-3. Dosimetry cross sections have been evaluated for 67 reactions on 47 nuclides together with covariances. The cross sections for 34 major reactions and their covariances were simultaneously generated, and the remaining 33 reaction data were mainly taken from JENDL/D-91. Latest measurements were taken into account in the evaluation. The resultant evaluated data are given in the neutron energy region below 20 MeV in both of point-wise and group-wise files in the ENDF-6 format. In order to confirm the reliability of the evaluated data, several integral tests have been carried out: comparisons with average cross sections measured in fission neutron fields, fast/thermal reactor spectra, DT neutron fields and Li(d,n) neutron fields. It was found from the comparisons that the cross sections calculated from JENDL/D-99 are generally in good agreement with the measured data. The contents of JENDL/D-99 and the results of the integral tests are described in this report. All of the dosimetry cross sections are shown in a graphical form in the Appendix. (author)

  6. Application of a new dosimetry formalism to volumetric modulated arc therapy (VMAT).

    Science.gov (United States)

    Rosser, Karen E; Bedford, James L

    2009-12-07

    Volumetric modulated arc therapy (VMAT) offers a challenge to classical dosimetry protocols as the beams are dynamic in orientation and aperture shape and may include small apertures. The aim of this paper is to apply a formalism to VMAT beams that has recently been published by the International Atomic Energy Agency (IAEA) working party to improve the dosimetry for small and non-standard fields. We investigated three possible fields and assessed their suitability as plan class specific reference (pcsr) fields. The factors in the new dosimetry formalism were investigated: the conversion of dose to water from the conventional reference field to the pcsr and then from the pcsr to a treatment plan, using a PTW semiflex chamber, two Farmer chambers and an electron diode. Finally, the dose was compared for Alanine, the new formalism and calculated using Pinnacle(3) (Philips Radiation Oncology Systems) for two typical clinical VMAT beams. Correction factors between the reference field and the pcsr determined with Alanine range from 0.1% to 2.3% for the three pcsr fields. Dose to water measured using the calibrated ionization chambers is less than 2% different to the dose calculated by Pinnacle(3). VMAT planning and delivery procedures have been successfully implemented and a new dosimetry protocol has been investigated for this new technique. Calibration factors for pcsr fields are found to be up to 2.3% different when using the new formalism, compared to using a standard dosimetry protocol. Using the calibration factors determined in the pcsr fields, the ionization chambers and electron diode agree to within 1% with Alanine dosimetry for two clinical VMAT plans. Good agreements between calculations and measurements are found for these two plans when the new formalism is used.

  7. Characteristics of Feeding Preference and Nutrients Utilization of Golden Apple Snail (Pomacea canaliculata on Macrophytes in Paddy Fields

    Directory of Open Access Journals (Sweden)

    Benliang Zhao

    2012-10-01

    Full Text Available Golden apple snail was a harmful invasive gastropod in Asian wetlands. In order to clarify the effect of Pomacea canaliculata on macrophytes in paddy fields, feeding preference and nutrients utilization of snail were studied. Feeding preference of snail was Alternanthera philoxenoides>Monochoria vaginalis>Oryza sativa L. Snail showed a higher approximate digestion coefficient on Oryza sativa L. than that on Monochoria vaginalis. Nitrogen utilization coefficient of snail on Alternanthera philoxenoides was significantly higher than that on Oryza sativa L. Snail exhibited a higher calcium utilization coefficient on Alternanthera philoxenoides and Monochoria vaginalis than that on Oryza sativa L. Oryza sativa L. was not preferred among three plants under the same available and exposure condition.

  8. Advanced Corneal Cross-Linking System with Fluorescence Dosimetry

    Directory of Open Access Journals (Sweden)

    Marc D. Friedman

    2012-01-01

    Full Text Available Purpose. This paper describes an advanced system that combines corneal cross-linking with riboflavin with fluorescence dosimetry, the ability to measure riboflavin diffusion within the cornea both before and during UVA treatment. Methods and Results. A corneal cross-linking system utilizing a digital micromirror device (DMD was assembled and used to measure diffusion coefficients of 0.1% riboflavin in 20% dextran in porcine eyes. A value of (3.3±0.2×10−7 cm2/s was obtained for the stroma. Diffusion coefficients for the transepithelial formulation of 0.1% riboflavin in 0.44% saline and 0.02% BAK were also measured to be 4.7±0.3×10−8 cm2/s for epithelium only and (4.6±0.4×10−7 cm2/s for stroma only. Riboflavin consumption during a UVA treatment was also demonstrated. Conclusion. A new advanced corneal cross-linking system with fluorescence dosimetry of riboflavin has been demonstrated. It is hoped that this method may play a significant role in determining the underlying mechanisms of corneal cross-linking and assist with the development of additional riboflavin formulations. Moreover, dosimetry may prove valuable in providing a method to account for the biological differences between individuals, potentially informing cornea-specific UVA treatment doses in real time.

  9. Ammonia Volatilization and Nitrogen Utilization Efficiency in Response to Urea Application in Rice Fields of the Taihu Lake Region, China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ammonia volatilization losses, nitrogen utilization efficiency, and rice yields in response to urea application to a rice field were investigated in Wangzhuang Town, Changshu City, Jiangsu Province, China. The N fertilizer treatments, applied in triplicate, were 0 (control), 100, 200, 300, or 350 kg N ha-1. After urea was applied to the surface water, a continuous airflow enclosure method was used to measure ammonia volatilization in the paddy field. Total N losses through ammonia volatilization generally increased with the N application rate, and the two higher N application rates (300 and 350 kg N ha-1) showed a higher ratio of N lost through ammonia volatilization to applied N. Total ammonia loss by ammonia volatilization during the entire rice growth stage ranged from 9.0% to 16.7% of the applied N. Increasing the application rate generally decreased the ratio of N in the seed to N in the plant. For all N treatments, the nitrogen fertilizer utilization efficiency ranged from 30.9% to 45.9%. Surplus N with the highest N rate resulted in lodging of rice plants, a decreased rate of nitrogen fertilizer utilization, and reduced rice yields. Calculated from this experiment, the most economical N fertilizer application rate was 227 kg ha-1 for the type of paddy soil in the Taihu Lake region. However, recommending an appropriate N fertilizer application rate such that the plant growth is enhanced and ammonia loss is reduced could improve the N utilization efficiency of rice.

  10. Realization of Field Sequential Color in Simple Matrix Antiferroelectric Liquid Crystal Displays by Utilizing Fast Pretransitional Response

    Science.gov (United States)

    Suzuki, Yasushi; Chen, Guo-Ping; Manna, Uttam; Vij, Jagdish K.; Fukuda, Atsuo

    2009-07-01

    Simple matrix antiferroelectric liquid crystal displays (SM-AFLCDs) are prototyped to realize field sequential color (FSC) by utilizing the fast pretransitional response. The developed FSC-SM-AFLCDs will lead to the replacement of existing static driven FSC-SM-nematic-LCDs. Bright and clear color can be given to already market-acquired, black-and-white SM-LCDs of up to 1/64-duty and 3-in. diagonal size. To optimize the display performance, we analyze two important factors, the large pretransitional effect and the appropriate reset pulse, in terms of the interlayer interaction potential used in describing the field-induced transition of the antiferroelectric smectic phase.

  11. Filter concepts for gas turbines. Overview and field report on utility value enhancement with three-stage filtration

    Energy Technology Data Exchange (ETDEWEB)

    Manstein, Heiko; Rothmann, Andreas [Scandinavia Freudenberg Filtration Technologies KG, Weinheim (Germany). Turbomachinery

    2009-07-01

    Efficient air filtration and its contribution towards cost-effective operation of gas turbines offer an extensive field for continual design enhancements. The utility value of three-stage, high-efficiency filter installations for gasturbine air intake systems was in terms of its basics covered by a previous publication. Feedback from multi-stage systems installed in the field validates the applicability to statically operated filter systems currently in common use, against the background of the stipulations posed for particle arrestance, coalescence characteristics and pressure-loss behaviour. (orig.)

  12. Relative dosimetry by Ebt-3; Dosimetria relativa por EBT3

    Energy Technology Data Exchange (ETDEWEB)

    De Leon A, M. A.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico); Hernandez O, J. O., E-mail: madla16@hotmail.com [Hospital General de Mexico, Dr. Balmis 148, Col. Doctores, 06726 Mexico D. F. (Mexico)

    2015-10-15

    In the present work relative dosimetry in two linear accelerator for radiation therapy was studied. Both Varian Oncology systems named Varian Clinac 2100-Cd and MLC Varian Clinac i X were used. Gaf Chromic Ebt-3 film was used. Measurements have been performed in a water equivalent phantom, using 6 MV and 18 MV photon beams on both Linacs. Both calibration and Electron irradiations were carried out with the ionization chamber placed at the isocenter, below a stack of solid water slabs, at the depth of dose maximum (D max), with a Source-to-Surface Distance (SSD) of 100 cm and a field size of 10 cm x 10 cm. Calibration and dosimetric measurements photons were carried out under IAEA-TRS 398 protocol. Results of relative dosimetry in the present work are discussed. (Author)

  13. Alternative statistical methods for cytogenetic radiation biological dosimetry

    CERN Document Server

    Fornalski, Krzysztof Wojciech

    2014-01-01

    The paper presents alternative statistical methods for biological dosimetry, such as the Bayesian and Monte Carlo method. The classical Gaussian and robust Bayesian fit algorithms for the linear, linear-quadratic as well as saturated and critical calibration curves are described. The Bayesian model selection algorithm for those curves is also presented. In addition, five methods of dose estimation for a mixed neutron and gamma irradiation field were described: two classical methods, two Bayesian methods and one Monte Carlo method. Bayesian methods were also enhanced and generalized for situations with many types of mixed radiation. All algorithms were presented in easy-to-use form, which can be applied to any computational programming language. The presented algorithm is universal, although it was originally dedicated to cytogenetic biological dosimetry of victims of a nuclear reactor accident.

  14. The specifics of dosimetry for food irradiation applications

    Science.gov (United States)

    Kuntz, Florent; Strasser, Alain

    2016-12-01

    Dose measurement applied to food irradiation is obviously a very important and critical aspect of this process. It is described in many standards and guides. The application of appropriate dosimetry tools is explained. This helps to ensure traceability of this measurement and number of dosimeters available on the market are well studied even though theirs response should be characterized while used in routine processing conditions. When employed in low energy radiation fields, these dosimeters may exhibit specific response compared to the usual Cobalt 60 source irradiation. Traceable calibration or correction factor assessment of this energy dependency is mandatory. It is to mention that the absorbed dose is measured in the dosimeter itself and unfortunately not in/on the food product. However, existing dosimetry systems fulfill all relevant requirements.

  15. Radiation Protection and Dosimetry An Introduction to Health Physics

    CERN Document Server

    Stabin, Michael G

    2007-01-01

    This comprehensive text provides an overview of all relevant topics in the field of radiation protection (health physics). Radiation Protection and Dosimetry serves as an essential handbook for practicing health physics professionals, and is also ideal as a teaching text for courses at the university level. The book is organized to introduce the reader to basic principles of radiation decay and interactions, to review current knowledge and historical aspects of the biological effects of radiation, and to cover important operational topics such as radiation shielding and dosimetry. In addition to presenting the most up to date treatment of the topics and references to the literature, most chapters contain numerical problems with their solutions for use in teaching or self assessment. One chapter is devoted to Environmental Health Physics, which was written in collaboration with leading professionals in the area.

  16. Dosimetry requirements derived from the sterilization standards

    DEFF Research Database (Denmark)

    Miller, A.

    1998-01-01

    The main standards for radiation sterilization, ISO 11137 and EN 552, rest the documentation for the properly executed sterilization process on dosimetry. Both standards describe general requirements to the dosimetry system: The dose measurements must be traceable to national standards, the uncer...

  17. A Noninvasive Magnetic Stimulator Utilizing Secondary Ferrite Cores and Resonant Structures for Field Enhancement

    CERN Document Server

    Pradhan, Raunaq

    2016-01-01

    In this paper, secondary ferrite cores and resonant structures have been used for field enhancement. The tissue was placed between the double square source coil and the secondary ferrite core. Resonant coils were added which aided in modulating the electric field in the tissue. The field distribution in the tissue was measured using electromagnetic simulations and ex-vivo measurements with tissue. Calculations involve the use of finite element analysis (Ansoft HFSS) to represent the electrical properties of the physical structure. The setup was compared to a conventional design in which the secondary ferrite cores were absent. It was found that the induced electric field could be increased by 122%, when ferrite cores were placed below the tissue at 450 kHz source frequency. The induced electric field was found to be localized in the tissue, verified using ex-vivo experiments. This preliminary study maybe further extended to establish the verified proposed concept with different complicated body parts modelled...

  18. Year 2000 compliance concerns with the ISA Thermoluminescent Dosimetry Data Processing (TL-DP) software system

    Energy Technology Data Exchange (ETDEWEB)

    Saviz, K.

    1998-05-26

    The year 2000 is rapidly approaching, and there is a good chance that computer systems that utilize two digit year dates will experience problems in retrieval of date information. The ISA Thermoluminescent Dosimetry Data Processing (TL-DP) software and computer system has been reviewed for Year 2000 compliance issues.

  19. Dosimetry using radiosensitive gels in radiotherapy: significance and methods; Dosimetrie par gels radiosensibles en radiotherapie. Interet et methodes

    Energy Technology Data Exchange (ETDEWEB)

    Gibon, D. [Dept. de Radiotherapie, Centre Oscar Lambret, Lille Cedex (France); Bourel, P. [Lab. de Biophysique, Inst. de Technologie Medicale, Centre Hospitalier Universitaire, Lille (France); Castelain, B. [Dept. de Radiotherapie, Centre Oscar Lambret, Lille Cedex (France); Marchandise, X.; Rousseau, J. [Lab. de Biophysique, Inst. de Technologie Medicale, Centre Hospitalier Universitaire, Lille (France)

    2001-02-01

    The goal of conformal radiotherapy is to concentrate the dose in a well-defined volume by avoiding the neighbouring healthy structures. This technique requires powerful treatment planning software and a rigorous control of estimated dosimetry. The usual dosimetric tools are not adapted to visualize and validate complex 3D treatment. Dosimetry by radiosensitive gel permits visualization and measurement of the three-dimensional dose distribution. The objective of this work is to report on current work in this field and, based on our results and our experience, to draw prospects for an optimal use of this technique. Further developments will relate to the realization of new radiosensitive gels satisfying, as well as possible, cost requirements, easy realization and use, magnetic resonance imagery (MRI) sensitivity, tissue equivalence, and stability. Other developments focus on scanning methods, especially in MRI to measure T1 and T2. (author)

  20. Utility bill comprehension in the commercial and industrialsector: results of field research

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Christopher T.

    2000-06-02

    This paper presents the results of interviews conducted with 44 business people in 10 states to examine the use of the utility bill as an information mechanism for providing businesses with the relationship between energy consumption and cost. Our results indicate that there are significant barriers to the use of the utility bill as an information tool for energy consumers. Furthermore, we found significant variations among respondents in the information desired from the bill, and differences in decision-making criteria for investments aimed at reducing energy consumption and for those aimed at other forms of waste minimization. These results call into question the applicability of standard market theories in the purchase of energy by most businesses.

  1. SU-E-T-559: Monte Carlo Simulation of Cobalt-60 Teletherapy Unit Modeling In-Field and Out-Of-Field Doses for Applications in Computational Radiation Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Petroccia, H; Bolch, W [J. Crayton Pruitt Family of Biomedical Engineering, University of Florida, Gainesville, FL (United States); Li, Z; Mendenhall, N [Radiation Oncology, UF Health Proton Therapy Institute, Jacksonville, FL (United States)

    2015-06-15

    Purpose: Mean organ doses from structures located in field and outside of field boundaries during radiotherapy treatment must be considered when looking at secondary effects. Treatment planning in patients with 40 years of follow-up does not include 3-D treatment planning images and did not estimate dose to structures out of the direct field. Therefore, it is of interest to correlate actual clinical events with doses received. Methods: Accurate models of radiotherapy machines combined with whole body computational phantoms using Monte Carlo methods allow for dose reconstructions intended for studies on late radiation effects. The Theratron-780 radiotherapy unit and anatomically realistic hybrid computational phantoms are modeled in the Monte Carlo radiation transport code MCNPX. The major components of the machine including the source capsule, lead in the unit-head, collimators (fixed/adjustable), and trimmer bars are simulated. The MCNPX transport code is used to compare calculated values in a water phantom with published data from BJR suppl. 25 for in-field doses and experimental data from AAPM Task Group No. 36 for out-of-field doses. Next, the validated cobalt-60 teletherapy model is combined with the UF/NCI Family of Reference Hybrid Computational Phantoms as a methodology for estimating organ doses. Results: The model of Theratron-780 has shown to be agree with percentage depth dose data within approximately 1% and for out of field doses the machine is shown to agree within 8.8%. Organ doses are reported for reference hybrid phantoms. Conclusion: Combining the UF/NCI Family of Reference Hybrid Computational Phantoms along with a validated model of the Theratron-780 allows for organ dose estimates of both in-field and out-of-field organs. By changing field size, position, and adding patient-specific blocking more complicated treatment set-ups can be recreated for patients treated historically, particularly those who lack both 2D/3D image sets.

  2. Teaching Methods Utilizing a Field Theory Viewpoint in the Elementary Reading Program.

    Science.gov (United States)

    LeChuga, Shirley; Lowry, Heath

    1980-01-01

    Suggests and lists sources of information on reading instruction that discuss the promotion and enrichment of the interactive learning process between children and their environment based on principles underlying the cognitive-field theory of learning. (MKM)

  3. History of dose specification in Brachytherapy: From Threshold Erythema Dose to Computational Dosimetry

    Science.gov (United States)

    Williamson, Jeffrey F.

    2006-09-01

    This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as a means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.

  4. ESR dosimetry using eggshells and tooth enamel for accidental dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Toshihide; Yamanaka, Chihiro; Ikeya, Motoji [Department of Earth and Space Science, Faculty of Science, Osaka Univ., Toyonaka, Osaka (Japan)

    1997-07-01

    The CO{sub 2}{sup -} signal of eggshells showed a good dose linearity and was appropriate in the wide dose range from 1 to 10 kGy, while ESR signal of CO{sub 2}{sup -} in sea and fresh water shells were saturated at a dose od below 10 kGy. The minimum detectable dose and G-value of CO{sub 2}{sup -} in eggshells were estimated 0.3 Gy and 0.28, respectively. The lifetime of CO{sub 2}{sup -} in eggshells could not be determined exactly because of overlapping organic signals, however it is still sufficiently long for practical use as ESR dosimeter materials. Various bird`s or reptile`s eggshells would be available as natural retrospective ESR dosimeter materials after nuclear accidents. Eggshells will be useful for the food irradiation dosimetry in the dose range of about a few kGy. Tooth enamel is one of the most useful dosimeter materials in public at a accident because of its high sensitivity. ESR dosimetry will replace TLD in near future if the cost of an ESR reader is further reduced . (author)

  5. Radiation dosimetry by potassium feldspar

    Indian Academy of Sciences (India)

    Arun Pandya; S G Vaijapurkar; P K Bhatnagar

    2000-04-01

    The thermoluminescence (TL) properties of raw and annealed feldspar have been studied for their use in gamma dosimetry. The raw gamma exposed feldspar shows glow peaks at 120°C and 319°C. Gamma dose beyond 500 cGy can be measured without any significant fading even after 40 days of termination of exposure. The annealed feldspar shows a glow peak at 120°C after gamma exposure. This peak can be used to measure gamma doses beyond 25 cGy when the TL is measured after 24 h from termination of exposure.

  6. Relocation of the Dosimetry Service

    CERN Multimedia

    2007-01-01

    The Dosimetry Service is moving from Building 24 to Building 55 and will therefore be closed on Friday, 30 March. From Monday, 2 April onwards you will find us in Building 55/1-001. Please note that we cannot exclude problems with Internet connections on that day and are therefore unable to guarantee normal service. The Service's opening hours and telephone number will not change as a result of the move: Open from 8.30 - 12.00. Closed in the afternoons. Tel. 7 2155

  7. Development and evaluation of a phantom for multi-purpose dosimetry in intensity-modulated radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae Sun; Kim, Chan Hyeong [Hanyang University, Seoul (Korea, Republic of); Park, Joo Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Han, Young Yih [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kum, O Yeon [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2011-08-15

    A LEGO-type multi-purpose dosimetry phantom was developed for intensity-modulated radiation therapy (IMRT), which requires various types of challenging dosimetry. Polystyrene, polyethylene, polytetrafluoroethylene (PTFE), and polyurethane foam (PU-F) were selected to represent muscle, fat, bone, and lung tissue, respectively, after considering the relevant mass densities, elemental compositions, effective atomic numbers, and photon interaction coefficients. The phantom, which is composed of numerous small pieces that are similar to LEGO blocks, provides dose and dose distribution measurements in homogeneous and heterogeneous media. The phantom includes dosimeter holders for several types of dosimeters that are frequently used in IMRT dosimetry. An ion chamber and a diode detector were used to test dosimetry in heterogeneous media under radiation fields of various sizes. The data that were measured using these dosimeters were in disagreement when the field sizes were smaller than 1.5 x 1.5 cm{sup 2} for polystyrene and PTFE, or smaller than 3 x 3 cm{sup 2} for an air cavity. The discrepancy was as large as 41% for the air cavity when the field size was 0.7 x 0.7 cm{sup 2}, highlighting one of the challenges of IMRT small field dosimetry. The LEGO-type phantom is also very useful for two-dimensional dosimetry analysis, which elucidates the electronic dis-equilibrium phenomena on or near the heterogeneity boundaries

  8. Field emission arrays fabricated utilizing conjugated ZnO quantum dot/carbon nanotube hybrid nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Wu Chaoxing [Institute of Optoelectronic Display, Fuzhou University, Fuzhou 350002 (China); Li Fushan, E-mail: fushanli@hotmail.com [Institute of Optoelectronic Display, Fuzhou University, Fuzhou 350002 (China); Zhang Yongai [Institute of Optoelectronic Display, Fuzhou University, Fuzhou 350002 (China); Guo Tailiang, E-mail: gtl@fzu.edu.cn [Institute of Optoelectronic Display, Fuzhou University, Fuzhou 350002 (China); Qu Bo; Chen Zhijian [State Key Laboratory for Mesoscopic Physics, Peking University, Beijing 100871 (China)

    2011-02-15

    In situ growth of ZnO quantum dots (QDs) on the surface of multiwalled carbon nanotube (MWCNTs) was realized via a mild solution-process method, and their application in field emission device was demonstrated. High resolution transmission electron microscopy observation revealed the conjugation between ZnO QDs and MWCNTs. Field emission arrays based on ZnO QD/MWCNT hybrid nanocomposite exhibited significantly improved luminance intensity and emitting dot density when compared with the MWCNT-only arrays. It is proposed that the introduction of the ZnO QDs on the sidewall of MWCNTs can enhance the tunnelling probability, and result in the improved field emission property for the hybrid emitters.

  9. Organic field-effect transistor nonvolatile memories utilizing sputtered C nanoparticles as nano-floating-gate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Liu, Chang-Hai; She, Xiao-Jian; Sun, Qi-Jun; Gao, Xu; Wang, Sui-Dong, E-mail: wangsd@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China)

    2014-10-20

    High-performance organic field-effect transistor nonvolatile memories have been achieved using sputtered C nanoparticles as the nano-floating-gate. The sputtered C nano-floating-gate is prepared with low-cost material and simple process, forming uniform and discrete charge trapping sites covered by a smooth and complete polystyrene layer. The devices show large memory window, excellent retention capability, and programming/reading/erasing/reading endurance. The sputtered C nano-floating-gate can effectively trap both holes and electrons, and it is demonstrated to be suitable for not only p-type but also n-type organic field-effect transistor nonvolatile memories.

  10. Trends in gel dosimetry: Preliminary bibliometric overview of active growth areas, research trends and hot topics from Gore’s 1984 paper onwards

    Science.gov (United States)

    Baldock, C.

    2017-05-01

    John Gore’s seminal 1984 paper on gel dosimetry spawned a vibrant research field ranging from fundamental science through to clinical applications. A preliminary bibliometric study was undertaken of the gel dosimetry family of publications inspired by, and resulting from, Gore’s original 1984 paper to determine active growth areas, research trends and hot topics from Gore’s paper up to and including 2016. Themes and trends of the gel dosimetry research field were bibliometrically explored by way of co-occurrence term maps using the titles and abstracts text corpora from the Web of Science database for all relevant papers from 1984 to 2016. Visualisation of similarities was used by way of the VOSviewer visualisation tool to generate cluster maps of gel dosimetry knowledge domains and the associated citation impact of topics within the domains. Heat maps were then generated to assist in the understanding of active growth areas, research trends, and emerging and hot topics in gel dosimetry.

  11. Utilization of Field Enhancement in Plasmonic Waveguides for Subwavelength Light-Guiding, Polarization Handling, Heating, and Optical Sensing

    Directory of Open Access Journals (Sweden)

    Daoxin Dai

    2015-10-01

    Full Text Available Plasmonic nanostructures have attracted intensive attention for many applications in recent years because of the field enhancement at the metal/dielectric interface. First, this strong field enhancement makes it possible to break the diffraction limit and enable subwavelength optical waveguiding, which is desired for nanophotonic integrated circuits with ultra-high integration density. Second, the field enhancement in plasmonic nanostructures occurs only for the polarization mode whose electric field is perpendicular to the metal/dielectric interface, and thus the strong birefringence is beneficial for realizing ultra-small polarization-sensitive/selective devices, including polarization beam splitters, and polarizers. Third, plasmonic nanostructures provide an excellent platform of merging electronics and photonics for some applications, e.g., thermal tuning, photo-thermal detection, etc. Finally, the field enhancement at the metal/dielectric interface helps a lot to realize optical sensors with high sensitivity when introducing plasmonic nanostrutures. In this paper, we give a review for recent progresses on the utilization of field enhancement in plasmonic nanostructures for these applications, e.g., waveguiding, polarization handling, heating, as well as optical sensing.

  12. Characterisation of OSL and OSLN droplets for dosimetry.

    Science.gov (United States)

    Nascimento, L F; D'Agostino, E; Vaniqui, A C S; Saldarriaga, C; Vanhavere, F; De Deene, Y

    2014-10-01

    In spite of considerable progress in neutron dosimetry, there is no dosemeter that is capable of measuring neutron doses independently of the neutron spectrum with good accuracy. Carbon-doped aluminium oxide (Al2O3:C) is a sensitive material for ionising radiation (beta-ray, X ray and electron) and has been used for applications in personal and medical dosimetry as an optically stimulated luminescence (OSL) dosemeter. Al2O3:C has a low sensitivity to neutron radiation; this prevents its application to neutron fields, representing a disadvantage of Al2O3:C-OSL when compared with LiF, which is used as a thermoluminescent detector. Recently an improvement for neutron dosimetry (Passmore and Kirr. Neutron response characterisation of an OSL neutron dosemeter. Radiat. Prot. Dosim. 2011; 144: 155-60) uses Al2O3:C coated with (6)Li2CO3 (OSLN),which gives the high-sensitive response as known for Al2O3:C with the advantage of being also sensitive to thermal neutrons. In this article, the authors compare small-size detectors (droplets) of Al2O3:C (OSL) and of Al2O3:C+(6)Li2CO3 (OSLN) and discuss the advantages and drawbacks of both materials, regarding size vs. response.

  13. The Chernobyl experience in the area of retrospective dosimetry.

    Science.gov (United States)

    Chumak, Vadim V

    2012-03-01

    The Chernobyl accident, which occurred on 26 April 1986 at a nuclear power plant located less than 150 km north of Kiev, was the largest nuclear accident to date. The unprecedented scale of the accident was determined not only by the amount of released activity, but also by the number of workers and of the general public involved, and therefore exposed to increased doses of ionising radiation. Due to the unexpected and large scale of the accident, dosimetry techniques and practices were far from the optimum; personal dosimetry of cleanup workers (liquidators) was not complete, and there were no direct measurements of the exposures of members of the public. As a result, an acute need for retrospective dose assessment was dictated by radiation protection and research considerations. In response, substantial efforts have been made to reconstruct doses for the main exposed cohorts, using a broad variety of newly developed methods: analytical, biological and physical (electron paramagnetic resonance spectroscopy of teeth, thermoluminescence of quartz) and modelling. This paper reviews the extensive experience gained by the National Research Center for Radiation Medicine, Academy of Medical Sciences, Ukraine in the field of retrospective dosimetry of large cohorts of exposed population and professionals. These dose reconstruction projects were implemented, in particular, in the framework of epidemiological studies, designed to follow-up the medical consequences of the Chernobyl accident and study health effects of ionizing radiation, particularly Ukrainian-American studies of cataracts and leukaemia among liquidators.

  14. Faraday caustics: Singularities in the Faraday spectrum and their utility as probes of magnetic field properties

    CERN Document Server

    Bell, M R; Enßlin, T A

    2011-01-01

    We describe singularities in the distribution of polarized intensity as a function of Faraday depth (i.e. the Faraday spectrum) that arise due to line of sight (LOS) magnetic field reversals. We call these features Faraday caustics due to their similarity to optical caustics. They appear sharply spiked in the Faraday spectrum with a tail that extends to one side. The direction in which the tail extends depends on the way in which the LOS magnetic field reversal occurs (either changing from oncoming to retreating or vice versa). We describe how surfaces of Faraday caustics relate to boundaries between regions where the LOS magnetic field has opposite polarity. Examples from simulations of the polarized synchrotron emission from the Milky Way are provided. We derive the probability or luminosity distribution of Faraday caustics produced in a Gaussian magnetic field distribution as a function of their strength, F, and find that for strong Faraday caustics P(F) ~ F^(-3). If fully resolved, this distribution is al...

  15. Giant electrocaloric effect in PZT bilayer thin films by utilizing the electric field engineering

    Science.gov (United States)

    Zhang, Tiandong; Li, Weili; Cao, Wenping; Hou, Yafei; Yu, Yang; Fei, Weidong

    2016-04-01

    The enhancement of the electrocaloric effect (ECE) was achieved by the amplifying effect of applied electric field through devising the thin films' structure. The PbZr0.95Ti0.05O3/PbZr0.52Ti0.48O3 bilayer structured thin films were fabricated on a Pt(111)/Ti/SiO2/Si substrate using sol-gel method. The ΔS = 20.5 J K-1 kg-1 and ΔT = 24.8 K for bilayer thin films is achieved around 125 °C much below Tc, which is caused by the amplifying electric field induced phase transition of OAFE/RFE in PZr0.95Ti0.05O3 layer. It is also worth mentioning that the films exhibit outstanding ECE at room temperature; ΔS = 11.9 J K-1 kg-1 and ΔT = 10.7 K are observed, which are attributed to the effect of amplifying electric field in PbZr0.95Ti0.05O3 layer and RFE/TFE at morphotropic phase boundaries (MPB) in PbZr0.52Ti0.48O3 layer. This result indicates that to amplify the local electric field engineering and to maximize the number of coexisting phases in heterostructures or multilayer thin films may be an effective way for cooling applications.

  16. Utilizing Geo-Referenced Mobile Game Technology for Universally Accessible Virtual Geology Field Trips

    Science.gov (United States)

    Bursztyn, Natalie; Pederson, Joel; Shelton, Brett; Walker, Andrew; Campbell, Todd

    2015-01-01

    Declining interest and low persistence is well documented among undergraduate students in Science, Technology, Engineering, and Math in the United States. For geoscience, field trips are important attractors to students, however with high enrollment courses and increasing costs they are becoming rare. We propose in this concept paper that the…

  17. The Metaphor of Scaffolding: Its Utility for the Field of Learning Disabilities.

    Science.gov (United States)

    Stone, C. Addison

    1998-01-01

    This critical analysis of the scaffolding metaphor for the field of learning disabilities first reviews the origins and early applications of the metaphor and criticisms of the metaphor raised by others. It proposes an enriched version of the metaphor which emphasizes the communicational dynamics and conceptual reorganization involved in…

  18. Laboratory and field testing for utilization of an excavated soil as landfill liner material.

    Science.gov (United States)

    Bozbey, Ilknur; Guler, Erol

    2006-01-01

    This study investigates the feasibility of using a silty soil excavated in highway construction as landfill liner material. The tests were conducted both at laboratory and in situ scales, and the soil was tested in pure and lime treated forms. Different levels of compaction energy were used. For the field study, a test pad was constructed and in situ hydraulic conductivity experiments were conducted by sealed double ring infiltrometers (SDRI). Laboratory testing revealed that while lime treatment improved the shear strength, it resulted in higher hydraulic conductivity values compared to pure soil. It was observed that leachate permeation did not change the hydraulic conductivity of the pure and lime treated samples. Laboratory hydraulic conductivities were on the order of 10(-9) m/s and met the 1.0E-08 m/s criterion in the Turkish regulations, which is one order of magnitude higher than the value allowed in most developed countries. SDRI testing, which lasted for 6 mo, indicated that lime treatment increased the hydraulic conductivity of pure soil significantly in the field scale tests. In situ hydraulic conductivities were on the order of 1E-08 and 1E-07 m/s, and exceeded the allowable value in the Turkish regulations. Undisturbed samples collected from the test pad were not representative of field hydraulic conductivities. Contrary to laboratory findings, higher compaction efforts did not result in lower hydraulic conductivities in field scales. The study verified the importance of in situ hydraulic conductivity testing in compacted liners.

  19. Propulsion Utilizing Laser-Driven Ponderomotive Fields for Deep-Space Missions

    Science.gov (United States)

    Williams, George J.; Gilland, James H.

    2009-03-01

    The generation of large amplitude electric fields in plasmas by high-power lasers has been studied for several years in the context of high-energy particle acceleration. Fields on the order of GeV/m are generated in the plasma wake of the laser by non-linear ponderomotive forces. The laser fields generate longitudinal and translational electron plasma waves with phase velocities close to the speed of light. These fields and velocities offer the potential to revolutionize spacecraft propulsion, leading to extended deep space robotic probes. Based on these initial calculations, plasma acceleration by means of laser-induced ponderomotive forces appears to offer significant potential for spacecraft propulsion. Relatively high-efficiencies appear possible with proper beam conditioning, resulting in an order of magnitude more thrust than alternative concepts for high ISP (>105 s) and elimination of the primary life-limiting erosion phenomena associated with conventional electric propulsion systems. Ponderomotive propulsion readily lends itself to beamed power which might overcome some of the constraints of power-limited propulsion concepts. A preliminary assessment of the impact of these propulsion systems for several promising configurations on mission architectures has been conducted. Emphasizing interstellar and interstellar-precursor applications, performance and technical requirements are identified for a number of missions. The use of in-situ plasma and gas for propellant is evaluated as well.

  20. Simulation of Magnetic Field Assisted Finishing (MFAF) Process Utilizing Smart MR Polishing Tool

    Science.gov (United States)

    Barman, Anwesa; Das, Manas

    2017-02-01

    Magnetic field assisted finishing process is an advanced finishing process. This process is capable of producing nanometer level surface finish. In this process magnetic field is applied to control the finishing forces using magnetorheological polishing medium. In the current study, permanent magnet is used to provide the required magnetic field in the finishing zone. The working gap between the workpiece and the magnet is filled with MR fluid which is used as the polishing brush to remove surface undulations from the top surface of the workpiece. In this paper, the distribution of magnetic flux density on the workpiece surface and behaviour of MR polishing medium during finishing are analyzed using commercial finite element packages (Ansys Maxwell® and Comsol®). The role of magnetic force in the indentation of abrasive particles on the workpiece surface is studied. A two-dimensional simulation study of the steady, laminar, and incompressible MR fluid flow behaviour during finishing process is carried out. The material removal and surface roughness modelling of the finishing process are also presented. The indentation force by a single active abrasive particle on the workpiece surface is modelled during simulation. The velocity profile of MR fluid with and without application of magnetic field is plotted. It shows non-Newtonian property without application of magnetic field. After that the total material displacement due to one abrasive particle is plotted. The simulated roughness profile is in a good agreement with the experimental results. The conducted study will help in understanding the fluid behavior and the mechanism of finishing during finishing process. Also, the modelling and simulation of the process will help in achieving better finishing performance.

  1. Electromagnetic and heat transfer computations for non-ionizing radiation dosimetry.

    Science.gov (United States)

    Samaras, T; Regli, P; Kuster, N

    2000-08-01

    Reliable information on the heat distribution inside biological tissues is essential for the planning and optimization of experiments which aim to study the effects of non-ionizing radiation (NIR). In electrodynamics, the finite-difference time-domain (FDTD) technique has become the dominant technique for radiofrequency dosimetry. In order to obtain the electromagnetic field and heat distributions within the same simulation run without changing discretization, a heat diffusion solver has been directly integrated into an advanced electrodynamic FDTD kernel. The implementation enables both coupled and sequential simulations. It also includes the ability to work with complex bodies and to accelerate heat diffusion. This paper emphasizes the importance of this combination in the field of NIR dosimetry. Two examples from this area are given: the validation of dosimetry with temperature probes and the estimation of the highest thermal load during bioexperiments.

  2. An Automated Biological Dosimetry System

    Science.gov (United States)

    Lorch, T.; Bille, J.; Frieben, M.; Stephan, G.

    1986-04-01

    The scoring of structural chromosome aberrations in peripheral human blood lymphocytes can be used in biological dosimetry to estimate the radiation dose which an individual has received. Especially the dicentric chromosome is a rather specific indicator for an exposure to ionizing radiation. For statistical reasons, in the low dose range a great number of cells must be analysed, which is a very tedious task. The resulting high cost of a biological dose estimation limits the application of this method to cases of suspected irradiation for which physical dosimetry is not possible or not sufficient. Therefore an automated system has been designed to do the major part of the routine work. It uses a standard light microscope with motorized scanning stage, a Plumbicon TV-camera, a real-time hardware preprocessor, a binary and a grey level image buffer system. All computations are performed by a very powerful multi-microprocessor-system (POLYP) based on a MIMD-architecture. The task of the automated system can be split in finding the metaphases (see Figure 1) at low microscope magnification and scoring dicentrics at high magnification. The metaphase finding part has been completed and is now in routine use giving good results. The dicentric scoring part is still under development.

  3. Video equipment of tele dosimetry and audio; Video equipo de teledosimetria y audio

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda R, M.A.; Padilla C, I. [CFE, Central Laguna Verde, Subgerencia General de Operacion, Proteccion Radiologica, Veracruz (Mexico)]. e-mail: aojega@cfe.gob.mx

    2007-07-01

    To develop a work in an area with high radiation, it requires of a detailed knowledge of the surroundings work, a communication and effective vision, a near dosimetric control. In a work where the spaces variables and reduced accesses exist, noise that hinders the communication, defendant operative condition, radiation field and taking of decision, it is necessary to have tools that allow a total control of the environment to make opportune and effective decisions, there where the task is developed. Under this elementary concept, it was developed in the Laguna Verde Central a project that it allowed a mechanism, interactive of control in spaces complex; to see, to hear, to speak, to measure. This concept takes to the creation of an equipped system with closed circuit of television, wireless communication systems, tele dosimetry wireless systems, VHS and DVD recording equipment, uninterrupted energy units. The system requires of an electric power socket, and the installation of two cables by CCTV camera. The system is mobilized by a person. He puts on in operation in 5 minutes using a verification list. The concept was developed in the project denominated VETA-1, (Video Equipment of Tele dosimetry and Audio). It is objective of this work to present before the society the development of the VETA-1 tool that conclude in their first prototype in May of the present year. The VETA-1 project arises by a necessity of optimizing dose, it is an ALARA tool, with a countless applications, like it was proven in the 12 recharge stop of the Unit 1. The VETA-1 project integrate a recording system, with the primary end of analyzing in the place where the task is developed the details for an effective and opportune decision, but the resulting information is of utility for the personnel's training and the planning of future works. The VETA-1 system is an ALARA tool of quick response control. (Author)

  4. X-ray dosimetry in mammography for Mo/Mo combination utilizing Compton spectrometry;Dosimetria de raios X em mamografia para combinacao Mo/Mo utilizando espectrometria Compton

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Jose Neres de; Terini, Ricardo Andrade, E-mail: rterini@pucsp.b [Pontificia Univ. Catolica de Sao Paulo (PUC-SP), SP (Brazil). Dept. de Fisica; Herdade, Silvio Bruni [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Eletrotecnica e Energia. Secao Tecnica de Desenvolvimento em Tecnologia em Saude; Furquim, Tania Aparecida Correia [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Eletrotecnica e Energia. Secao Tecnica de Aplicacoes em Diagnostico por Imagem

    2010-08-15

    Objective: to compare mammography benefit and X-ray induced cancer risk, one should investigate absorbed doses. For this purpose, spectra of primary X-ray beams from a clinical mammography equipment were determined for Mo/Mo target/filter combination, using Compton spectrometry and average glandular dose (AGD) in a BR-12 breast phantom was evaluated. Material and Method: a CdTe detector was used for spectrometry of X-ray beams Compton scattered {approx} 100 deg, by a PMMA cylinder, for different depths inside the BR-12 phantom and voltages between 28 and 35 kV. The reconstruction of the primary beam spectra from the measured ones was followed by the determination of AGD. Results: half-value layer values determined by spectra resulted 0.39 to 0.45 mmAl, and by ionization chamber, 0.38 to 0.42 mmAl, respectively, for beams incident on the phantom surface. The AGDN normalized per unitary incident air kerma, on the BR-12 surface, ranged from 0.156 to 0.226. Conclusion: the percentage deviation of AGD{sub N}, relative to the chamber measurements, ranged from 1% to 3%. The utilized method is a good alternative to determine AGD{sub N} and depth-dose distributions in breast phantoms. (author)

  5. Estimating output fluence with MCNP4 for shaped fields and their comparison with measurements in the EPID system aS1000 for dosimetry 2D in-vivo; Estimacion de la fluencia de salida con MCNP4 para campos conformados y su comparacion con mediciones en el sistema EPID aS1000 para dosimetria in-vivo 2D

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez R, B.; Rodriguez P, X.; Sosa, M., E-mail: bhernandez@fisica.ugto.mx [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Loma del Bosque No. 103, 37150 Leon, Guanajuato (Mexico)

    2015-10-15

    Full text: Radiotherapy dosimetry is a fundamental process in quality control of the treatments performed with this technique. Different systems exist to quantify radiation dose in radiotherapy, one of them is the Electronic Portal Imaging Device (EPID), which is widely used in IMRT to measure the output fluence of a radiation field for comparison with a predicted fluence in a planning system. The objective of this work was to simulate a Varian linear accelerator model Clinac i X using the MCNP4 code for obtaining curves of percentage depth dose (Pdd) and open fields dosimetric profiles of 5 x 5, 10 x 10, 20 x 20 and 30 x 30 cm{sup 2}. The simulations were validated by comparing them with measurements made with ionization chamber. Then a mannequin of solid water (30 x 30 x 20 cm{sup 3}) with an open field of 10 x 10 cm{sup 2} was irradiated to measure the output fluence with EPID aS1000 system of Varian. A simulation of the solid water mannequin under the same conditions of irradiation was conducted to estimate the output fluence. Tests of index gamma and percentage differences were calculated to compare that simulated with that measured. In all cases was found that more than 95% of the evaluated points passed the acceptance criteria (ΔD= 1% and ΔS= 1 mm for curves Pdd and profiles, and ΔD= 3% and ΔS= 3 mm for fluence two-dimensional). This paper will contribute to the implementation of in-vivo dosimetry three-dimensional with the EPID system. (Author)

  6. Artificial neural networks in neutron dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Hernandez D, V.M.; Manzanares A, E.; Mercado, G.A.; Perales M, W.A.; Robles R, J.A. [Unidades Academicas de Estudios Nucleares, UAZ, A.P. 336, 98000 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Depto. de Ingenieria Nuclear, Universidad Politecnica de Madrid, (Spain)

    2005-07-01

    An artificial neural network has been designed to obtain the neutron doses using only the Bonner spheres spectrometer's count rates. Ambient, personal and effective neutron doses were included. 187 neutron spectra were utilized to calculate the Bonner count rates and the neutron doses. The spectra were transformed from lethargy to energy distribution and were re-binned to 31 energy groups using the MCNP 4C code. Re-binned spectra, UTA4 response matrix and fluence-to-dose coefficients were used to calculate the count rates in Bonner spheres spectrometer and the doses. Count rates were used as input and the respective doses were used as output during neural network training. Training and testing was carried out in Mat lab environment. The artificial neural network performance was evaluated using the {chi}{sup 2}- test, where the original and calculated doses were compared. The use of Artificial Neural Networks in neutron dosimetry is an alternative procedure that overcomes the drawbacks associated in this ill-conditioned problem. (Author)

  7. The Conformer Specific Rotational Spectrum of 3-PHENYLPROPIONITRILE Utilizing Strong Field Coherence Breaking

    Science.gov (United States)

    Fritz, Sean; Hernandez-Castillo, Alicia O.; Abeysekera, Chamara; Zwier, Timothy S.

    2017-06-01

    The 8-18 GHz conformer specific rotational spectrum of gauche- and anti-3-phenylpropionitrile (C6H5-CH2-CH2-CN) conformers has been recorded using the strong field coherence breaking (SFCB) technique [1] with a modified line picking scheme for multiple selective excitations (MSE). As the recombination product of benzyl and cyanomethyl resonance-stabilized radicals, 3-phenylpropionitrile is a likely component of the complex organics in Titan's atmosphere, motivating its structural characterization. Details of the modified line picking scheme, hyperfine constants and relative population ratios of the two conformers will be presented. [1] A.O Hernandez-Castillo, Chamara Abeysekera, Brian M. Hays, Timothy S. Zwier, "Broadband Multi-Resonant Strong Field Coherence Breaking as a Tool for Single Isomer Microwave Spectroscopy." J. Chem. Phys. 145, 114203 (2016).

  8. Wide-Field OCT Angiography at 400 KHz Utilizing Spectral Splitting

    Directory of Open Access Journals (Sweden)

    Laurin Ginner

    2014-10-01

    Full Text Available Optical angiography systems based on optical coherence tomography (OCT require dense sampling in order to maintain good vascular contrast. We demonstrate a way to gain acquisition speed and spatial sampling by using spectral splitting with a swept source OCT system. This method splits the recorded spectra into two to several subspectra. Using continuous lateral scanning, the lateral sampling is then increased by the same factor. This allows increasing the field of view of OCT angiography, while keeping the same transverse resolution and measurement time. The performance of our method is demonstrated in vivo at different locations of the human retina and verified quantitatively. Spectral splitting can be applied without any changes in the optical setup, thus offering an easy way to increase the field of view of OCT in general and in particular for OCT angiography.

  9. Keratocyte fragments and cells utilize competing pathways to move in opposite directions in an electric field.

    Science.gov (United States)

    Sun, Yaohui; Do, Hao; Gao, Jing; Zhao, Ren; Zhao, Min; Mogilner, Alex

    2013-04-08

    Sensing of an electric field (EF) by cells-galvanotaxis-is important in wound healing [1], development [2], cell division, nerve growth, and angiogenesis [3]. Different cell types migrate in opposite directions in EFs [4], and the same cell can switch the directionality depending on conditions [5]. A tug-of-war mechanism between multiple signaling pathways [6] can direct Dictyostelium cells to either cathode or anode. Mechanics of motility is simplest in fish keratocytes, so we turned to keratocytes to investigate their migration in EFs. Keratocytes sense electric fields and migrate to the cathode [7, 8]. Keratocyte fragments [9, 10] are the simplest motile units. Cell fragments from leukocytes are able to respond to chemotactic signals [11], but whether cell fragments are galvanotactic was unknown. We found that keratocyte fragments are the smallest motile electric field-sensing unit: they migrate to the anode, in the opposite direction of whole cells. Myosin II was essential for the direction sensing of fragments but not for parental cells, while PI3 kinase was essential for the direction sensing of whole cells but not for fragments. Thus, two signal transduction pathways, one depending on PI3K, another on myosin, compete to orient motile cells in the electric field. Galvanotaxis is not due to EF force and does not depend on cell or fragment size. We propose a "compass" model according to which protrusive and contractile actomyosin networks self-polarize to the front and rear of the motile cell, respectively, and the electric signal orients both networks toward cathode with different strengths.

  10. Exposure to electromagnetic fields from smart utility meters in GB; part I) laboratory measurements.

    Science.gov (United States)

    Peyman, Azadeh; Addison, Darren; Mee, Terry; Goiceanu, Cristian; Maslanyj, Myron; Mann, Simon

    2017-05-01

    Laboratory measurements of electric fields have been carried out around examples of smart meter devices used in Great Britain. The aim was to quantify exposure of people to radiofrequency signals emitted from smart meter devices operating at 2.4 GHz, and then to compare this with international (ICNIRP) health-related guidelines and with exposures from other telecommunication sources such as mobile phones and Wi-Fi devices. The angular distribution of the electric fields from a sample of 39 smart meter devices was measured in a controlled laboratory environment. The angular direction where the power density was greatest was identified and the equivalent isotropically radiated power was determined in the same direction. Finally, measurements were carried out as a function of distance at the angles where maximum field strengths were recorded around each device. The maximum equivalent power density measured during transmission around smart meter devices at 0.5 m and beyond was 15 mWm(-2) , with an estimation of maximum duty factor of only 1%. One outlier device had a maximum power density of 91 mWm(-2) . All power density measurements reported in this study were well below the 10 W m(-2) ICNIRP reference level for the general public. Bioelectromagnetics. 2017;38:280-294. © 2017 Crown copyright. BIOELECTROMAGNETICS © 2017 Wiley Periodicals, Inc.

  11. Introduction to radiological physics and radiation dosimetry

    CERN Document Server

    Attix, Frank Herbert

    2004-01-01

    A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as photographic, calorimetric, chemical, and thermoluminescence dosimetry. Includes many new derivations, such as Kramers X-ray spectrum, as well as topics that have not been thoroughly analyzed in other texts, such as broad-beam attenuation and geometrics, and the reciprocity theorem

  12. Manipulating quantum dot fluorescence by utilizing Brownian induced near-field interactions with plasmonic nanoparticles

    Science.gov (United States)

    Palombo, Nola

    Quantum dots (QDs) are semiconductor nanocrystals with size-dependent optical properties; thus making them supreme fluorophores. Plasmonic nanoparticles (PNPs), such as gold and silver nanoparticles, support localized surface plasmons on their surface. When the localized surface plasmons are excited, a highly concentrated electromagnetic field is formed near the particle. Therefore, if a QD is within the near-field of a PNP, the emission or excitation of the QD can be enhanced. However, due to Forster Resonance Energy Transfer (FRET), the QD fluorescence could instead be quenched by the proximity of PNPs. Whether enhancement or quenching occurs, is dependent upon the distance and geometry of the nanoparticles. Enhanced QD fluorescence would be helpful in biomedical sensing and imaging and solar energy conversion applications. In addition, quenched QD fluorescence caused by FRET could be applied to FRET-based sensing and imaging in medical diagnosis. This master's thesis first theoretically models the stochastic movement of QDs and PNPs in an aqueous solution. The simulation is based upon the Direct Simulation Monte Carlo method coupled with Langevin equations. Using this simulation, we were able to predict the percentage of QDs in the near-field region of PNPs. The percentage of QDs in the near-field region of GNPs for a concentration of 1 × 1013 QDs/mL and 5 × 108 GNPs/mL, is a very small percentage of 2 × 10-5%. Yet, the concentration of QDs in the near-field region of GNPs was calculated to be 1,510,000 QDs mL-1. In addition, this master's thesis experimentally explores the enhancement and quenching of QD emission for different concentrations and sizes of PNPs in aqueous solutions. The fluorescence spectra of two types of QD-PNP mixtures were measured. The first mixture was QDs and gold nanoparticles (GNPs) dispersed in distilled water, where the emission wavelength of the QDs matches the localized surface plasmon excitation wavelength of the GNPs. The second

  13. Updating and extending the IRDF-2002 dosimetry library

    Energy Technology Data Exchange (ETDEWEB)

    Capote, R. [International Atomic Energy Agency, NAPC-Nuclear Data Section, Vienna (Austria); Zolotarev, K.I.; Pronyaev, V.G. [Inst. of Physics and Power Engineering, Obninsk, Kaluga Region (Russian Federation); Trkov, A. [Jozef Stefan Inst., Ljubljana (Slovenia)

    2011-07-01

    The International Reactor Dosimetry File (IRDF)-2002 released in 2004 by the IAEA (see http://www-nds.iaea.org/irdf2002/) contains cross-section data and corresponding uncertainties for 66 dosimetry reactions. New cross-section evaluations have become available recently that re-define some of these dosimetry reactions including: (1) high-fidelity evaluation work undertaken by one of the authors (KIZ); (2) evaluations from the US ENDF/B-VII.0 and candidate evaluations from the US ENDF/B-VII.1 libraries that cover reactions within the International Evaluation of Neutron Cross-Section Standards; (3) European JEFF3.1 library; and (4) Japanese JENDL-4.0 library. Additional high-threshold reactions not included in IRDF-2002 (e.g., {sup 59C}o(n,3n) and {sup 209}Bi(n,3n)) have been also evaluated to characterize higher-energy neutron fields. Overall, 37 new evaluations of dosimetry reactions have been assessed and intercomparisons made with integral measurements in reference neutron fields to determine whether they should be adopted to update and improve IRDF-2002. Benchmark calculations performed for newly evaluated reactions using the ENDF/B-VII.0 {sup 235}U thermal fission and {sup 252}Cf spontaneous fission neutron spectra show that calculated integral cross sections exhibit improved agreement with evaluated experimental data when compared with the equivalent data from the IRDF-2002 library. Data inconsistencies or deficiencies of new evaluations have been identified for {sup 63}Cu(n,2n), {sup 60}Ni(n,p) {sup 60m+g}Co, {sup 55}Mn(n,{gamma}), and {sup 232}Th(n,f) reactions. Compared with IRDF-2002, the upper neutron energy boundary was formally increased from the actual maximum energy of typically 20 MeV up to 60 MeV by using the TENDL-2010 cross sections and covariance matrices. This extension would allow the updated IRDF library to be also used in fusion dosimetry applications. Uncertainties in the cross sections for all new evaluations are given in the form of

  14. Utilizing an Artificial Outcrop to Scaffold Learning Between Laboratory and Field Experiences in a College-Level Introductory Geology Course

    Science.gov (United States)

    Wilson, Meredith

    Geologic field trips are among the most beneficial learning experiences for students as they engage the topic of geology, but they are also difficult environments to maximize learning. This action research study explored one facet of the problems associated with teaching geology in the field by attempting to improve the transition of undergraduate students from a traditional laboratory setting to an authentic field environment. Utilizing an artificial outcrop, called the GeoScene, during an introductory college-level non-majors geology course, the transition was studied. The GeoScene was utilized in this study as an intermediary between laboratory and authentic field based experiences, allowing students to apply traditional laboratory learning in an outdoor environment. The GeoScene represented a faux field environment; outside, more complex and tangible than a laboratory, but also simplified geologically and located safely within the confines of an educational setting. This exploratory study employed a mixed-methods action research design. The action research design allowed for systematic inquiry by the teacher/researcher into how the students learned. The mixed-methods approach garnered several types of qualitative and quantitative data to explore phenomena and support conclusions. Several types of data were collected and analyzed, including: visual recordings of the intervention, interviews, analytic memos, student reflections, field practical exams, and a pre/post knowledge and skills survey, to determine whether the intervention affected student comprehension and interpretation of geologic phenomena in an authentic field environment, and if so, how. Students enrolled in two different sections of the same laboratory course, sharing a common lecture, participated in laboratory exercises implementing experiential learning and constructivist pedagogies that focused on learning the basic geological skills necessary for work in a field environment. These laboratory

  15. Possibilities of Utilization the Risk – Based Techniques in the Field of Offshore Wind Power Plants

    Directory of Open Access Journals (Sweden)

    Przemysław Kacprzak

    2014-09-01

    Full Text Available In the article the risk-based concept that may be applicable to offshore wind power plants has been presented. The aim of the concept is to aid designers in the early design and retrofit phases of the project in case of lack or insufficient information in relevant international standards. Moreover the initial classification of components within main system parts of offshore wind power plant has been performed. Such classification is essential in order to apply risk-based concept. However further scientific researches need to be performed in that field to develop detailed concept useful for future practical applications.

  16. Near-field enhanced optical tweezers utilizing femtosecond-laser nanostructured substrates

    CERN Document Server

    Kotsifaki, Domna G; Lagoudakis, Pavlos G

    2015-01-01

    We present experimental evidence of plasmonic-enhanced optical tweezers, of polystyrene beads in deionized water in the vicinity of metal-coated nanostructures. The optical tweezers operate with a continuous wave (CW) near-infrared laser. We employ a Cu/Au bilayer that significantly improves dissipation of heat generated by the trapping laser beam and avoid de-trapping from heat convection currents. We investigate the improvement of the optical trapping force, the effective trapping quality factor, and observe an exponential distance dependence of the trapping force from the nanostructures, expected from the evanescent plasmon field.

  17. Preliminary utilization of Iran's ERTS-1 data in the field of geology and water resources

    Science.gov (United States)

    Akhavi, M. S.; Ebtehadj, K.

    1973-01-01

    Preliminary analysis of a number of selected ERTS-1 images undertaken in the fields of geology and water resources for the purpose of testing its applicability and usefulness for mapping the natural resources of Iran identified a number of geologic and hydrologic phenomena, such as previously unknown faults, streams, and lakes. Due to a number of limiting factors, the results of this study are by no means conclusive; yet, the encouraging results obtained demonstrate the importance of satellite imagery for multidisciplinary resource analysis purposes in Iran.

  18. Utilizing self-assembled-monolayer-based gate dielectrics to fabricate molybdenum disulfide field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kawanago, Takamasa, E-mail: kawanago.t.ab@m.titech.ac.jp; Oda, Shunri [Quantum Nanoelectronics Research Center (QNERC), Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550 (Japan)

    2016-01-25

    In this study, we apply self-assembled-monolayer (SAM)-based gate dielectrics to the fabrication of molybdenum disulfide (MoS{sub 2}) field-effect transistors. A simple fabrication process involving the selective formation of a SAM on metal oxides in conjunction with the dry transfer of MoS{sub 2} flakes was established. A subthreshold slope (SS) of 69 mV/dec and no hysteresis were demonstrated with the ultrathin SAM-based gate dielectrics accompanied by a low gate leakage current. The small SS and no hysteresis indicate the superior interfacial properties of the MoS{sub 2}/SAM structure. Cross-sectional transmission electron microscopy revealed a sharp and abrupt interface of the MoS{sub 2}/SAM structure. The SAM-based gate dielectrics are found to be applicable to the fabrication of low-voltage MoS{sub 2} field-effect transistors and can also be extended to various layered semiconductor materials. This study opens up intriguing possibilities of SAM-based gate dielectrics in functional electronic devices.

  19. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    Science.gov (United States)

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-01-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry. PMID:27181521

  20. Raising the avermectins production in Streptomyces avermitilis by utilizing nanosecond pulsed electric fields (nsPEFs)

    Science.gov (United States)

    Guo, Jinsong; Ma, Ruonan; Su, Bo; Li, Yinglong; Zhang, Jue; Fang, Jing

    2016-05-01

    Avermectins, a group of anthelmintic and insecticidal agents produced from Streptomyces avermitilis, are widely used in agricultural, veterinary, and medical fields. This study presents the first report on the potential of using nanosecond pulsed electric fields (nsPEFs) to improve avermectin production in S. avermitilis. The results of colony forming units showed that 20 pulses of nsPEFs at 10 kV/cm and 20 kV/cm had a significant effect on proliferation, while 100 pulses of nsPEFs at 30 kV/cm exhibited an obvious effect on inhibition of agents. Ultraviolet spectrophotometry assay revealed that 20 pulses of nsPEFs at 15 kV/cm increased avermectin production by 42% and reduced the time for reaching a plateau in fermentation process from 7 days to 5 days. In addition, the decreased oxidation reduction potential (ORP) and increased temperature of nsPEFs-treated liquid were evidenced to be closely associated with the improved cell growth and fermentation efficiency of avermectins in S. avermitilis. More importantly, the real-time RT-PCR analysis showed that nsPEFs could remarkably enhance the expression of aveR and malE in S. avermitilis during fermentation, which are positive regulator for avermectin biosynthesis. Therefore, the nsPEFs technology presents an alternative strategy to be developed to increase avermectin output in fermentation industry.

  1. Field-Reversed Configuration Formation Scheme Utilizing a Spheromak and Solenoid Induction

    Energy Technology Data Exchange (ETDEWEB)

    Gerhardt, S. P.; Belova, E. V.; Yamada, M.; Ji, H.; Ren, B.; McGeehan, B.; Inomoto, M.

    2008-06-12

    A new field-reversed configuration (FRC) formation technique is described, where a spheromak transitions to a FRC with inductive current drive. The transition is accomplished only in argon and krypton plasmas, where low-n kink modes are suppressed; spheromaks with a lighter majority species, such as neon and helium, either display a terminal tilt-mode, or an n=2 kink instability, both resulting in discharge termination. The stability of argon and krypton plasmas through the transition is attributed to the rapid magnetic diffusion of the currents that drive the kink-instability. The decay of helicity during the transition is consistent with that expected from resistivity. This observation indicates a new scheme to form a FRC plasma, provided stability to low-n modes is maintained, as well as a unique situation where the FRC is a preferred state.

  2. Co thickness dependence of structural and magnetic properties in spin quantum cross devices utilizing stray magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Kaiju, H., E-mail: kaiju@es.hokudai.ac.jp; Kasa, H.; Mori, S.; Misawa, T.; Abe, T.; Nishii, J. [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Komine, T. [Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan)

    2015-05-07

    We investigate the Co thickness dependence of the structural and magnetic properties of Co thin-film electrodes sandwiched between borate glasses in spin quantum cross (SQC) devices that utilize stray magnetic fields. We also calculate the Co thickness dependence of the stray field between the two edges of Co thin-film electrodes in SQC devices using micromagnetic simulation. The surface roughness of Co thin films with a thickness of less than 20 nm on borate glasses is shown to be as small as 0.18 nm, at the same scanning scale as the Co film thickness, and the squareness of the hysteresis loop is shown to be as large as 0.96–1.0. As a result of the establishment of polishing techniques for Co thin-film electrodes sandwiched between borate glasses, we successfully demonstrate the formation of smooth Co edges and the generation of stray magnetic fields from Co edges. Theoretical calculation reveals that a strong stray field beyond 6 kOe is generated when the Co thickness is greater than 10 nm at a junction gap distance of 5 nm. From these experimental and calculation results, it can be concluded that SQC devices with a Co thickness of 10–20 nm can be expected to function as spin-filter devices.

  3. Protocol for emergency EPR dosimetry in fingernails

    OpenAIRE

    Trompier, F; Kornak, L.; Calas, C.; Romanyukha, A.; LeBlanc, B.; Mitchell, C. A.; Swartz, H M; Clairand, I.

    2007-01-01

    There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail...

  4. Development of radiation biological dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chul Koo; Kim, Tae Hwan; Lee, Yun Sil; Son, Young Sook; Kim, Soo Kwan; Jang, Won Suk; Le, Sun Joo; Jee, Young Heun; Jung, Woo Jung

    1999-04-01

    Up until now, only a few methods have been developed for radiation biological dosimetry such as conventional chromosome aberration and micronucleus in peripheral blood cell. However, because these methods not only can be estimated by the expert, but also have a little limitation due to need high technique and many times in the case of radiation accident, it is very difficult to evaluate the absorbed dose of victims. Therefore, we should develop effective, easy, simple and rapid biodosimetry and its guideline (triage) to be able to be treated the victims as fast as possible. We established the premature chromosome condensation assay and apoptotic fragment assay which was the significant relationship between dose and cell damages to evaluate the irradiation dose as correct and rapid as possible using lymphocytes and crypt cells, and compared with conventional chromosome aberration assay and micronuclei assay.

  5. Advanced materials in radiation dosimetry

    CERN Document Server

    Bruzzi, M; Nava, F; Pini, S; Russo, S

    2002-01-01

    High band-gap semiconductor materials can represent good alternatives to silicon in relative dosimetry. Schottky diodes made with epitaxial n-type 4 H SiC and Chemical Vapor Deposited diamond films with ohmic contacts have been exposed to a sup 6 sup 0 Co gamma-source, 20 MeV electrons and 6 MV X photons from a linear accelerator to test the current response in on-line configuration in the dose range 0.1-10 Gy. The released charge as a function of the dose and the radiation-induced current as a function of the dose-rate are found to be linear. No priming effects have been observed using epitaxial SiC, due to the low density of lattice defects present in this material.

  6. Fiber-coupled Al2O3:C radioluminescence dosimetry for total body irradiations

    DEFF Research Database (Denmark)

    Buranurak, Siritorn; Andersen, Claus E.

    2016-01-01

    in the context of Total Body Irradiations (TBIs) where patients are treated with large fields of 6 or 18 MV photons at an extended source-to-surface distance (SSD). The study shows that Al2O3:C dosimetry using the saturated-RL protocol may be suitable for real-time in vivo dosimetry during TBI treatments from...... the perspective of the good agreement with alanine dosimetry and other critical phantom tests, including the ability to cope with the large stem signal experienced during TBI treatments at extended SSD. In contrast, the chromatic stem removal technique often used for organic plastic scintillators did not work...... caveat can therefore be removed from the list of potential problems associated with fiber-coupled Al2O3:C dosimetry using the saturated-RL protocol. This further has implications for TBI dosimetry using the RL Al2O3:C system due to large dose-rate differences between calibrations at the iso...

  7. Cutaneous papilloma and squamous cell carcinoma therapy utilizing nanosecond pulsed electric fields (nsPEF.

    Directory of Open Access Journals (Sweden)

    Dong Yin

    Full Text Available Nanosecond pulsed electric fields (nsPEF induce apoptotic pathways in human cancer cells. The potential therapeutic effective of nsPEF has been reported in cell lines and in xenograft animal tumor model. The present study investigated the ability of nsPEF to cause cancer cell death in vivo using carcinogen-induced animal tumor model, and the pulse duration of nsPEF was only 7 and 14 nano second (ns. An nsPEF generator as a prototype medical device was used in our studies, which is capable of delivering 7-30 nanosecond pulses at various programmable amplitudes and frequencies. Seven cutaneous squamous cell carcinoma cell lines and five other types of cancer cell lines were used to detect the effect of nsPEF in vitro. Rate of cell death in these 12 different cancer cell lines was dependent on nsPEF voltage and pulse number. To examine the effect of nsPEF in vivo, carcinogen-induced cutaneous papillomas and squamous cell carcinomas in mice were exposed to nsPEF with three pulse numbers (50, 200, and 400 pulses, two nominal electric fields (40 KV/cm and 31 KV/cm, and two pulse durations (7 ns and 14 ns. Carcinogen-induced cutaneous papillomas and squamous carcinomas were eliminated efficiently using one treatment of nsPEF with 14 ns duration pulses (33/39 = 85%, and all remaining lesions were eliminated after a 2nd treatment (6/39 = 15%. 13.5% of carcinogen-induced tumors (5 of 37 were eliminated using 7 ns duration pulses after one treatment of nsPEF. Associated with tumor lysis, expression of the anti-apoptotic proteins Bcl-xl and Bcl-2 were markedly reduced and apoptosis increased (TUNEL assay after nsPEF treatment. nsPEF efficiently causes cell death in vitro and removes papillomas and squamous cell carcinoma in vivo from skin of mice. nsPEF has the therapeutic potential to remove human squamous carcinoma.

  8. Development a high-resolution radiation dosimetry system based on Fricke solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vedelago, J. [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Mattea, F. [Universidad Nacional de Cordoba, Facultad de Ciencias Quimicas, Departamento de Quimica Organica, Ciudad Universitaria, 5000 Cordoba (Argentina); Valente, M., E-mail: josevedelago@gmail.com [Instituto de Fisica E. Gaviola, Oficina 102 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2014-08-15

    Due to the growing complexity of modern medical procedures involving the use of ionizing radiation, dosimetry by non-conventional techniques is one of the research areas in the field of greatest interest nowadays. Tissue-equivalent high-resolution dosimetry systems capable of attaining continuous dose mapping are required. In this scenario, Fricke gel dosimetry is a very promising option for in-phantom dose measurements in complex radiation techniques. Implementation of this technique requires dedicated instruments capable of measuring and performing the immediate in situ analysis of the acquired data at the radiation facility. The versatility of Fricke gel dosimetry in different applications depending on the chemical and isotopic composition of the dosimeter extends its application to different high performance conventional and non-conventional radiation procedures involving diverse types of radiation treatments and also radiation diagnosis procedures. This work presents an integral dosimetry system, based on Fricke gel solutions and their analysis by optical techniques, aiming for an increase in the precision on dose determinations. The chemical synthesis and dosimeter preparation were accomplished at LIIFAMIRx facilities, following the procedures and protocols described in previous works. Additionally, specific instrumentation for optical sample analysis was completely designed and constructed at LIIFAMIRx facilities. The main outcome of this work was the development of a methodology that improves the integral dose determination performance by the pre-irradiation of Fricke gel dosimeters. (author)

  9. Fundamentals of materials, techniques and instrumentation for OSL and FNTD dosimetry

    Science.gov (United States)

    Akselrod, M. S.

    2013-02-01

    The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al2O3:C as a material of choice for many dosimetric applications including fiberoptic OSL/RL sensors with diameters as small as 300 μm. A new RL/OSL fiberoptic system has a high potential for in vivo and in vitro dosimetry in both radiation therapy and diagnostic mammography. Different aspects of instrumentation, data processing algorithms, post-irradiation and real-time measurements are described. The next technological breakthrough was done with Fluorescent Nuclear Track detectors (FNTD) that has some important advantages in measuring fast neutron and high energy heavy charge particles that became the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology were engineered and successfully demonstrated for occupational and accident dosimetry, for medical dosimetry and radiobiological research.

  10. UTILIZATION OF PULSED ELECTROMAGNETIC FIELD AND TRADITIONAL PHYSIOTHERAPY IN KNEE OSTEOARTHRITIS MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Kadrya H. Battecha

    2015-04-01

    Full Text Available Background and Objectives: Pulsed electromagnetic field (PEMF has been suggested as a treatment method for musculoskeletal system disorders. The present study was conducted to determine whether the addition of PEMF to traditional physiotherapy produces better clinical outcomes than traditional physiotherapy alone in the management of moderate knee osteoarthritis (OA. Design: A single-blinded, randomized controlled study Methods: Twenty subjects (5 men and 15 women with unilateral moderate knee OA (Kellgren-Lawrence criteria grade 2. They were randomly allocated in 2 groups to receive: group (A PEMF plus ultrasound plus exercises; or (B ultrasound plus exercises. Both groups received the respective treatments 3 times per week for 4 weeks and underwent the same pretreatment and post treatment evaluation that included active knee range of motion (ROM by universal goniometer, knee pain score by visual analogue scale (VAS and knee functional performance by Western Ontario and McMaster Universities osteoarthritis index (WOMAC. Result: There was an improvement in both groups in active knee flexion ROM, reduced VAS score and improved WOMAC index , however, all outcomes were significantly better in group (A (p <0.05. Moreover, the percentages of outcomes improvement were in favor of group (A. Conclusion: The addition of PEMF to traditional physiotherapy in managing Knee OA produced a greater improvement in pain relief, range of motion and resulted in better functional performance than did traditional physiotherapy alone. The improvement in current study should be limited to short term outcomes of PEMF.

  11. Smith-Purcell experiment utilizing a field-emitter array cathode measurements of radiation

    CERN Document Server

    Ishizuka, H; Yokoo, K; Shimawaki, H; Hosono, A

    2001-01-01

    Smith-Purcell (SP) radiation at wavelengths of 350-750 nm was produced in a tabletop experiment using a field-emitter array (FEA) cathode. The electron gun was 5 cm long, and a 25 mmx25 mm holographic replica grating was placed behind the slit provided in the anode. A regulated DC power supply accelerated electron beams in excess of 10 mu A up to 45 keV, while a small Van de Graaff generator accelerated smaller currents to higher energies. The grating had a 0.556 mu m period, 30 deg. blaze and a 0.2 mu m thick aluminum coating. Spectral characteristics of the radiation were measured both manually and automatically; in the latter case, the spectrometer was driven by a stepping motor to scan the wavelength, and AD-converted signals from a photomultiplier tube were processed by a personal computer. The measurement, made at 80 deg. relative to the electron beam, showed good agreement with theoretical wavelengths of the SP radiation. Diffraction orders were -2 and -3 for beam energies higher than 45 keV, -3 to -5 ...

  12. Pulse-resolved radiotherapy dosimetry using fiber-coupled organic scintillators

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg

    fiber-coupled organic scintillators and data acquisition hardware, was developed at the Radiation Research Division at Risø DTU and tested using clinical x-ray beams at hospitals in Denmark and abroad. Measurements of output factors and percentage depth dose were performed and compared with reference......This PhD project pertains to the development and adaptation of a dosimetry system that can be used to verify the delivery of radiation in modern radiotherapy modalities involving small radiation fields and dynamic radiation delivery. The dosimetry system is based on fibre-coupled organic...

  13. Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

    Energy Technology Data Exchange (ETDEWEB)

    Kerkhoff, Lee; Williams, Kenneth H.; Long, Philip E.; McGuinness, L.

    2011-02-15

    Uranium contaminated groundwaters are a legacy concern for the U.S. Department of Energy. Previous experiments at the Rifle, Colorado Integrated Field Challenge (IFC) site have demonstrated that field-scale addition of acetate to groundwater reduces the ambient soluable uranium concentration, sequestering the radionuclide as uraninite. However, questions remain regarding which microorganism(s) are consuming this acetate and if active groundwater microorganisms are different from active particle-associated bacteria. In this report, 13-C acetate was used to assess the active microbes that synthesize DNA on 3 size fractions [coarse sand, fines (8-approximately 150 micron), groundwater (0.2-8 micron)] over a 24 -day time frame. Results indicated a stronger signal from 13-C acetate associated with the “fines” fraction compared with smaller amounts of 13-C uptake on the sand fraction and groundwater samples during the SIP incubations. TRFLP analysis of this 13-C-labeled DNA, indicated 31+ 9 OTU's with 6 peaks dominating the active profiles (166, 187, 210, 212, and 277 bp peaks using MnlI). Cloning/sequencing of the amplification products indicated a Geobacter-like group (187, 210, 212 bp) primarily synthesized DNA from acetate in the groundwater phase, an alpha Proteobacterium (166 bp) primarily grew on the fines/sands, and an Acinetobacter sp. (277 bp) utilized much of the 13C acetate in both groundwater and particle-associated phases. These findings will help to delineate the acetate utilization patterns of bacteria during field-scale acetate addition and can lead to improved methods for stimulating distinct microbial populations in situ.

  14. International Intercomparison Exercise for Nuclear Accident Dosimetry at the DAF Using GODIVA-IV

    Energy Technology Data Exchange (ETDEWEB)

    Hickman, David [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hudson, Becka [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-15

    The Nuclear Criticality Safety Program operated under the direction of Dr. Jerry McKamy completed the first NNSA Nuclear Accident Dosimetry exercise on May 27, 2016. Participants in the exercise were from Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), Savanah River Site (SRS), Pacific Northwest National Laboratory (PNNL), US Navy, the Atomic Weapons Establishment (United Kingdom) under the auspices of JOWOG 30, and the Institute for Radiological Protection and Nuclear Safety (France) by special invitation and NCSP memorandum of understanding. This exercise was the culmination of a series of Integral Experiment Requests (IER) that included the establishment of the Nuclear Criticality Experimental Research Center, (NCERC) the startup of the Godiva Reactor (IER-194), the establishment of a the Nuclear Accident Dosimetry Laboratory (NAD LAB) in Mercury, NV, and the determination of reference dosimetry values for the mixed neutron and photon radiation field of Godiva within NCERC.

  15. Fourth conference on radiation protection and dosimetry: Proceedings, program, and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Casson, W.H.; Thein, C.M.; Bogard, J.S. [eds.

    1994-10-01

    This Conference is the fourth in a series of conferences organized by staff members of Oak Ridge National Laboratory in an effort to improve communication in the field of radiation protection and dosimetry. Scientists, regulators, managers, professionals, technologists, and vendors from the United States and countries around the world have taken advantage of this opportunity to meet with their contemporaries and peers in order to exchange information and ideas. The program includes over 100 papers in 9 sessions, plus an additional session for works in progress. Papers are presented in external dosimetry, internal dosimetry, radiation protection programs and assessments, developments in instrumentation and materials, environmental and medical applications, and on topics related to standards, accreditation, and calibration. Individual papers are indexed separately on EDB.

  16. Chemolithotrophic acetogenic H2/CO2 utilization in Italian rice field soil.

    Science.gov (United States)

    Liu, Fanghua; Conrad, Ralf

    2011-09-01

    Acetate oxidation in Italian rice field at 50 °C is achieved by uncultured syntrophic acetate oxidizers. As these bacteria are closely related to acetogens, they may potentially also be able to synthesize acetate chemolithoautotrophically. Labeling studies using exogenous H(2) (80%) and (13)CO(2) (20%), indeed demonstrated production of acetate as almost exclusive primary product not only at 50 °C but also at 15 °C. Small amounts of formate, propionate and butyrate were also produced from (13)CO(2). At 50 °C, acetate was first produced but later on consumed with formation of CH(4). Acetate was also produced in the absence of exogenous H(2) albeit to lower concentrations. The acetogenic bacteria and methanogenic archaea were targeted by stable isotope probing of ribosomal RNA (rRNA). Using quantitative PCR, (13)C-labeled bacterial rRNA was detected after 20 days of incubation with (13)CO(2). In the heavy fractions at 15 °C, terminal restriction fragment length polymorphism, cloning and sequencing of 16S rRNA showed that Clostridium cluster I and uncultured Peptococcaceae assimilated (13)CO(2) in the presence and absence of exogenous H(2), respectively. A similar experiment showed that Thermoanaerobacteriaceae and Acidobacteriaceae were dominant in the (13)C treatment at 50 °C. Assimilation of (13)CO(2) into archaeal rRNA was detected at 15 °C and 50 °C, mostly into Methanocellales, Methanobacteriales and rice cluster III. Acetoclastic methanogenic archaea were not detected. The above results showed the potential for acetogenesis in the presence and absence of exogenous H(2) at both 15 °C and 50 °C. However, syntrophic acetate oxidizers seemed to be only active at 50 °C, while other bacterial groups were active at 15 °C.

  17. A convective divertor utilizing a 2nd-order magnetic field null

    Science.gov (United States)

    Rognlien, Thomas

    2014-10-01

    New results motivate a detailed study of a magnetic divertor concept characterized by strong plasma convection near a poloidal magnetic field (Bp) null region. The configuration is that of a near-2nd-order Bp null (Bp ~ Δ r2) , as in a snowflake divertor. The concept has 2 key features: (A) Convection spreads the heat flux between multiple divertor legs and further broadens the heat-flux profile within each leg, thereby greatly reducing target-plate heat loads. (B) The heat flux is further reduced by line radiation in each leg in detachment-like ionization zones. Theory indicates that convective turbulence arises when the poloidal plasma beta, βp = 2μ0nT/B p 2 >> 1 . Measurements in TCV now more fully quantify earlier NSTX and TCV observations of plasma mixing, and related modeling of TCV indicates that strongly enhanced null-region transport is present. Convective mixing provides a stabilizing mechanism to prevent the ionization fronts (hydrogenic and impurity) from collapsing to a highly radiating core MARFE. Also, the radiating zone maps to a very small region at the midplane owing to the very weak Bp in the convective region, thus minimizing its impact on the core plasma. Detailed calculations are reported that combine features A and B noted above. The plasma mixing mechanisms are described together with the corresponding transport model implemented in the 2D UEDGE edge transport code. UEDGE calculations are presented that quantify the roles of mixing, impurity radiation, and detachment stability for a realistic snowflake configuration. Work in collaboration with D.D. Ryutov, S.I. Krasheninnikov, and M.V. Umansky. Performed for the U.S. DoE by LLNS, LLC, LLNL, under Contract DE-AC52-07NA27344.

  18. Calibration facility for environment dosimetry instruments

    Energy Technology Data Exchange (ETDEWEB)

    Bercea, Sorin; Celarel, Aurelia; Cenusa, Constantin [Horia Hulubei National Institute for Physics and Nuclear Engineering, 30 Reactorului St, Magurele, Jud Ilfov, P.O.B. MG-6, RO-077125 (Romania)

    2013-12-16

    In the last ten years, the nuclear activities, as well as the major nuclear events (see Fukushima accident) had an increasing impact on the environment, merely by contamination with radioactive materials. The most conferment way to quickly identify the presence of some radioactive elements in the environment, is to measure the dose-equivalent rate H. In this situation, information concerning the values of H due only to the natural radiation background must exist. Usually, the values of H due to the natural radiation background, are very low (∼10{sup −9} - 10{sup −8} Sv/h). A correct measurement of H in this range involve a performing calibration of the measuring instruments in the measuring range corresponding to the natural radiation background lead to important problems due to the presence of the natural background itself the best way to overlap this difficulty is to set up the calibration stand in an area with very low natural radiation background. In Romania, we identified an area with such special conditions at 200 m dept, in a salt mine. This paper deals with the necessary requirements for such a calibration facility, as well as with the calibration stand itself. The paper includes also, a description of the calibration stand (and images) as well as the radiological and metrological parameters. This calibration facilities for environment dosimetry is one of the few laboratories in this field in Europe.

  19. Calibration facility for environment dosimetry instruments

    Science.gov (United States)

    Bercea, Sorin; Celarel, Aurelia; Cenusa, Constantin

    2013-12-01

    In the last ten years, the nuclear activities, as well as the major nuclear events (see Fukushima accident) had an increasing impact on the environment, merely by contamination with radioactive materials. The most conferment way to quickly identify the presence of some radioactive elements in the environment, is to measure the dose-equivalent rate H. In this situation, information concerning the values of H due only to the natural radiation background must exist. Usually, the values of H due to the natural radiation background, are very low (˜10-9 - 10-8 Sv/h). A correct measurement of H in this range involve a performing calibration of the measuring instruments in the measuring range corresponding to the natural radiation background lead to important problems due to the presence of the natural background itself the best way to overlap this difficulty is to set up the calibration stand in an area with very low natural radiation background. In Romania, we identified an area with such special conditions at 200 m dept, in a salt mine. This paper deals with the necessary requirements for such a calibration facility, as well as with the calibration stand itself. The paper includes also, a description of the calibration stand (and images) as well as the radiological and metrological parameters. This calibration facilities for environment dosimetry is one of the few laboratories in this field in Europe.

  20. A portable multi-purpose OSL reader for UV dosimetry at workplaces

    Energy Technology Data Exchange (ETDEWEB)

    Smetana, F. [Atomic Institute of the Austrian Universities, Vienna University of Technology, Stadionallee 2, AT-1020 Vienna (Austria); Hajek, M. [Atomic Institute of the Austrian Universities, Vienna University of Technology, Stadionallee 2, AT-1020 Vienna (Austria)], E-mail: mhajek@ati.ac.at; Bergmann, R. [Atomic Institute of the Austrian Universities, Vienna University of Technology, Stadionallee 2, AT-1020 Vienna (Austria); Brusl, H. [Austrian Social Insurance for Occupational Risks, Adalbert-Stifter-Strasse 65, AT-1200 Vienna (Austria); Fugger, M. [Atomic Institute of the Austrian Universities, Vienna University of Technology, Stadionallee 2, AT-1020 Vienna (Austria); Gratzl, W. [WEGS Data, Gatterholzgasse 14, AT-1120 Vienna (Austria); Kitz, E. [Austrian Social Insurance for Occupational Risks, Adalbert-Stifter-Strasse 65, AT-1200 Vienna (Austria); Vana, N. [Atomic Institute of the Austrian Universities, Vienna University of Technology, Stadionallee 2, AT-1020 Vienna (Austria)

    2008-02-15

    Optically stimulated luminescence (OSL) techniques are used for environmental radiation monitoring, luminescence dating and retrospective dosimetry. A portable and robust field instrument has been developed for the routine assessment of occupational exposure to ultraviolet (UV) radiation at workplaces. The design principles of hard- and software are described, along with preliminary measurements that illustrate the operation of the system and its capabilities.

  1. Anthropomorphic Phantom Radiation Dosimetry at the NATO Standard Reference Point at Aberdeen Proving Ground,

    Science.gov (United States)

    1987-04-01

    will have a non-isotropic angular dependance . Thus, for free-field dosimetry, while the bubble detector results could be directly transformed * into...these experiments was the bubble dosimeter temperature dependance . In all experiments, the phantom was surrounded by a tent arrangement (see figs) in

  2. Characterizing a pulse-resolved dosimetry system for complex radiotherapy beams using organic scintillators

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Ottosson, Rickard; Lindvold, Lars René;

    2011-01-01

    field at 10 cm depth. The dose per pulse behaviour compared well with linac target current measurements and accumulated dose measurements, and the system was able to resolve transient dose delivery differences between two Varian linac builds. The system therefore shows promise for reference dosimetry...

  3. Tenth ORNL Personnel Dosimetry Intercomparison Study

    Energy Technology Data Exchange (ETDEWEB)

    Swaja, R.E.; Chou, T.L.; Sims, C.S.; Greene, R.T.

    1985-03-01

    The Tenth Personnel Dosimetry Intercomparison Study was conducted at the Oak Ridge National Laboratory during April 9-11, 1984. Dosemeter badges from 31 participating organizations were mounted on 40cm Lucite phantoms and exposed to a range of dose equivalents which could be encountered during routine personnel monitoring in mixed radiation fields. The Health Physics Research Reactor served as the only source of radiation for eight of the ten irradiations which included a low (approx. 0.50 mSv) and high (approx. 10.00 mSv) neutron dose equivalent run for each of four shield conditions. Two irradiations were also conducted for which concrete- and Lucite-shield reactor irradiations were gamma-enhanced using a /sup 137/Cs source. Results indicated that some participants had difficulty obtaining measurable indication of neutron and gamma exposures at dose equivalents less than about 0.50 mSv and 0.20 mSv, respectively. Albedo dosemeters provided the best overall accuracy and precision for the neutron measurements. Direct interaction TLD systems showed significant variation in accuracy with incident spectrum, and threshold neutron dosemeters (film and recoil track) underestimated reference values by more than 50%. Gamma dose equivalents estimated in the mixed fields were higher than reference values with TL gamma dosemeters generally yielding more accurate results than film. Under the conditions of this study in which participants had information concerning exposure conditions and radiation field characteristics prior to dosemeter evaluation, only slightly more than half of all reported results met regulatory standards for neutron and gamma accuracy. 19 refs., 2 figs., 29 tabs.

  4. Design and optimization of anode flow field of a large proton exchange membrane fuel cell for high hydrogen utilization

    Science.gov (United States)

    Yesilyurt, Serhat; Rizwandi, Omid

    2016-11-01

    We developed a CFD model of the anode flow field of a large proton exchange membrane fuel cell that operates under the ultra-low stoichiometric (ULS) flow conditions which intend to improve the disadvantages of the dead-ended operation such as severe voltage transient and carbon corrosion. Very small exit velocity must be high enough to remove accumulated nitrogen, and must be low enough to retain hydrogen in the active area. Stokes equations are used to model the flow distribution in the flow field, Maxwell-Stefan equations are used to model the transport of the species, and a voltage model is developed to model the reactions kinetics. Uniformity of the distribution of hydrogen concentration is quantified as the normalized area of the region in which the hydrogen mole fraction remains above a certain level, such as 0.9. Geometry of the anode flow field is modified to obtain optimal configuration; the number of baffles at the inlet, width of the gaps between baffles, width of the side gaps, and length of the central baffle are used as design variables. In the final design, the hydrogen-depleted region is less than 0.2% and the hydrogen utilization is above 99%. This work was supported by The Scientific and Technolo-gical Research Council of Turkey, TUBITAK-213M023.

  5. Design and performance issues of RF coils utilized in ultra high field MRI: experimental and numerical evaluations.

    Science.gov (United States)

    Ibrahim, Tamer S; Kangarlu, Alayar; Chakeress, Donald W

    2005-07-01

    In this paper, two TEM resonators were evaluated experimentally and numerically at 8 tesla (T) (340 MHz for 1H imaging). The coils were constructed to be 21.2-cm long (standard) and 11-cm long (a proposed less claustrophobic design). The experimental evaluation was done on a single cadaver using an ultra high field, 8 T, whole-body magnet. The numerical modeling was performed using an in-house finite difference time domain packagethat treats the coil and the load (anatomically detailed human head model) as a single system. The coils were tested with quadrature excitation at different coil alignment positions with respect to human head. For head imaging at 8 T, the overall numerical and experimental results demonstrated that when compared to the longer coil, the shorter coil provides superior signal-to-noise ratio, coil sensitivity, and excite field in the biological regions that lie within both of the coils' structures. A study of the RF (excite/receive fields) homogeneity showed variations in the performance of both coils that are mostly dependant on the region of interest and the position of coil with respect to the head. As such, depending on the application, the shorter coil could be effectively utilized.

  6. Uncertainty in 3D gel dosimetry

    Science.gov (United States)

    De Deene, Yves; Jirasek, Andrew

    2015-01-01

    Three-dimensional (3D) gel dosimetry has a unique role to play in safeguarding conformal radiotherapy treatments as the technique can cover the full treatment chain and provides the radiation oncologist with the integrated dose distribution in 3D. It can also be applied to benchmark new treatment strategies such as image guided and tracking radiotherapy techniques. A major obstacle that has hindered the wider dissemination of gel dosimetry in radiotherapy centres is a lack of confidence in the reliability of the measured dose distribution. Uncertainties in 3D dosimeters are attributed to both dosimeter properties and scanning performance. In polymer gel dosimetry with MRI readout, discrepancies in dose response of large polymer gel dosimeters versus small calibration phantoms have been reported which can lead to significant inaccuracies in the dose maps. The sources of error in polymer gel dosimetry with MRI readout are well understood and it has been demonstrated that with a carefully designed scanning protocol, the overall uncertainty in absolute dose that can currently be obtained falls within 5% on an individual voxel basis, for a minimum voxel size of 5 mm3. However, several research groups have chosen to use polymer gel dosimetry in a relative manner by normalizing the dose distribution towards an internal reference dose within the gel dosimeter phantom. 3D dosimetry with optical scanning has also been mostly applied in a relative way, although in principle absolute calibration is possible. As the optical absorption in 3D dosimeters is less dependent on temperature it can be expected that the achievable accuracy is higher with optical CT. The precision in optical scanning of 3D dosimeters depends to a large extend on the performance of the detector. 3D dosimetry with X-ray CT readout is a low contrast imaging modality for polymer gel dosimetry. Sources of error in x-ray CT polymer gel dosimetry (XCT) are currently under investigation and include inherent

  7. SU-C-BRE-04: Microbeam-Radiation-Therapy (MRT): Characterizing a Novel MRT Device Using High Resolution 3D Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Q [Duke University, Durham, NC (United States); Juang, T; Bache, S [Durham, NC (United States); Chang, S [UNC School of Medicine, Chapel Hill, NC (United States); Oldham, M [Duke University Medical Center, Durham, NC (United States)

    2014-06-15

    Purpose: The feasibility of MRT has recently been demonstrated utilizing a new technology of Carbon-Nano-Tube(CNT) field emission x-ray sources.This approach can deliver very high dose(10's of Gy) in narrow stripes(sub-mm) of radiation which enables the study of novel radiation treatment approaches. Here we investigate the application of highresolution (50um isotropic) PRESAGE/Optical-CT 3D dosimetry techniques to characterize the radiation delivered in this extremely dosimetrically challenging scenario. Methods: The CNT field emission x-ray source irradiator comprises of a linear cathode array and a novel collimator alignment system. This allows a precise delivery of high-energy small beams up to 160 kVp. A cylindrical dosimeter (∼2.2cm in height ∼2.5cm in diameter) was irradiated by CNT MRT delivering 3 strips of radiation with a nominal entrance dose of 32 Gy.A second dosimeter was irradiated with similar entrance dose, with a regular x-ray irradiator collimated to microscopical strip-beams. 50um (isotropic) 3D dosimetry was performed using an in-house optical-CT system designed and optimized for high resolution imaging (including a stray light deconvolution correction).The percentage depth dose (PDD), peak-to-valley ratio (PVR) and beam width (FWHM) data were obtained and analyzed in both cases. Results: High resolution 3D images were successfully achieved with the prototype system, enabling extraction of PDD and dose profiles. The PDDs for the CNT irradiation showed pronounced attenuation, but less build-up effect than that from the multibeam irradiation. The beam spacing between the three strips has an average value of 0.9mm while that for the 13 strips is 1.5 mm at a depth of 16.5 mm. The stray light corrected image shows line profiles with reduced noise and consistent PVR values. Conclusion: MRT dosimetry is extremely challenging due to the ultra small fields involved.This preliminary application of a novel, ultra-high resolution, optical-CT 3D

  8. Geobacter sulfurreducens subsp. ethanolicus, subsp. nov., an ethanol-utilizing dissimilatory Fe(III)-reducing bacterium from a lotus field.

    Science.gov (United States)

    Viulu, Samson; Nakamura, Kohei; Kojima, Akihiro; Yoshiyasu, Yuki; Saitou, Sakiko; Takamizawa, Kazuhiro

    2013-01-01

    An ethanol-utilizing Fe(III)-reducing bacterial strain, OSK2A(T), was isolated from a lotus field in Aichi, Japan. Phylogenetic analysis of the 16S rRNA gene sequences of OSK2A(T) and related strains placed it within Geobacter sulfurreducens PCA(T). Strain OSK2A(T) was shown to be a Gram-negative, motile, rod-shaped bacterium, strictly anaerobic, 0.76-1.65 µm long and 0.28-0.45 μm wide. Its growth occurred at 20-40℃, pH 6.0-8.1, and it tolerated up to 1% NaCl. The G+C content of the genomic DNA was 61.2 mol% and DNA-DNA hybridization value with Geobacter sulfurreducens PCA(T) was 60.7%. The major respiratory quinone was MK-8. The major fatty acids were 16:1 ω7c, 16:0, 14:0, 15:0 iso, 16:1 ω5c, and 18:1 ω7c. Strain OSK2A(T) could utilize H2, ethanol, acetate, lactate, pyruvate, and formate as substrates with Fe(III)-citrate as electron acceptor. Amorphous Fe(III) hydroxide, Fe(III)-NTA, fumarate, malate, and elemental sulfur were utilized as electron acceptors with either acetate or ethanol as substrates. Results obtained from physiological, DNA-DNA hybridization, and chemotaxonomic tests support genotypic and phenotypic differentiation of strain OSK2A(T) from its closest relative. The isolate is assigned as a novel subspecies with the name Geobacter sulfurreducens subsp. ethanolicus, subsp. nov. (type strain OSK2A(T)=DSMZ 26126(T)=JCM 18752(T)).

  9. Utilization of 100 mb midlatitude height fields as an indicator of sampling effects on total ozone variations

    Science.gov (United States)

    Miller, A. J.; Nagatani, R. M.; Laver, J. D.; Korty, B.

    1979-01-01

    Midlatitude 100-mb height fields are employed to determine the effects of ground based sampling locations on measurements of variations in the total ozone content of the atmosphere. The precision of the zonal average heights computed by the technique of Angell and Korshover (1978) from data over ozone sampling areas at 50 deg N is compared to the zonal average computed from the entire data set. Linear regressions of ozone contents determined by an analysis of backscatter UV satellite data with respect to 100 mb heights are utilized to transform zonal differences in height to ozone levels. The zonal average total ozone sampling error is found to be on the order of 2% for midlatitudes of the Northern hemisphere, indicating that the general shape of ozone trends determined by ground-based observations appears to be real and the increase of ozone from the mid-1960's to the early 1970's may be greater than previously suggested.

  10. Direct utilization of geothermal resources field experiments at Monroe, Utah. Final report, July 14, 1978-July 13, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Blair, C.K.; Owen, L.B. (eds.)

    1982-12-01

    The City of Monroe, Utah undertook a project to demonstrate the economic and technical viability of utilizing a low temperature geothermal resource to provide space and hot water heating to commercial, municipal, and domestic users within the community. During the course of the project, resource development and assessment, including drilling of a production well, was successfully completed. Upon completion of the field development and assessment phase of the program and of a preliminary design of the district heating system, it was determined that the project as proposed was not economically viable. This was due to: (1) a significant increase in estimated capital equipment costs resulting from the general inflation in construction costs, the large area/low population density in Monroe, and a more remote fluid disposal well site than planned, could not balance increased construction costs, (2) a lower temperature resource than predicted, and (3) due to predicted higher pumping and operating costs. After a thorough investigation of alternatives for utilizing the resource, further project activities were cancelled because the project was no longer economical and an alternative application for the resource could not be found within the constraints of the project. The City of Monroe, Utah is still seeking a beneficial use for the 600 gpm, 164/sup 0/F geothermal well. A summary of project activities included.

  11. Utilizing NASA Earth Observations to Monitor Land Management Practices and the Development of Marshlands to Rice Fields in Rwanda

    Science.gov (United States)

    Dusabimana, M. R.; Blach, D.; Mwiza, F.; Muzungu, E.; Swaminathan, R.; Tate, Z.

    2014-12-01

    Rwanda, a small country with the highest population density in Sub-Saharan Africa, is one of the world's poorest countries. Although agriculture is the backbone of Rwandan economy, agricultural productivity is extremely low. Over 90 % of the population is engaged in subsistence farming and only 52 % of the total land surface area is arable. Of this land, approximately 165,000 hectares are marshlands, of which only 57 % has been cultivated. Rwandan government has invested in the advancement of agriculture with activities such as irrigation, marshland reclamation, and crop regionalization. In 2001, Ministry of Agriculture and Animal Resources (MINAGRI) released the Rural Sector Support Program (RSSP), which aimed at converting marshlands into rice fields at various development sites across the country. The focus of this project was to monitor rice fields in Rwanda utilizing NASA Earth observations such as Landsat 5 Thematic Mapper and Landsat 8 Operational Land Imager. Modified Normalized Difference Water Index (MNDWI) was used to depict the progress of marshland to rice field conversion as it highlights the presence of irrigated rice fields from the surrounding area. Additionally, Decision Support System for Agrotechnology Transfer (DSSAT) was used to estimate rice yield at RSSP sites. Various simulations were run to find perfect conditions for cultivating the highest yield for a given farm. Furthermore, soil erosion susceptibility masks were created by combining factors derived from ASTER, MERRA, and ground truth data using Revised Universal Soil Loss Equation (RUSLE). The end results, maps, and tutorials were delivered to the partners and policy makers in Rwanda to help make informed decisions. It can be clearly seen that Earth observations can be successfully used to monitor agricultural and land management practices as a cost effective method that will enable farmers to improve crop yield production and food security.

  12. In aqua vivo EPID dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Wendling, Markus; McDermott, Leah N.; Mans, Anton; Olaciregui-Ruiz, Igor; Pecharroman-Gallego, Raul; Sonke, Jan-Jakob; Stroom, Joep; Herk, Marcel J.; Mijnheer, Ben van [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands)

    2012-01-15

    Purpose: At the Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital in vivo dosimetry using an electronic portal imaging device (EPID) has been implemented for almost all high-energy photon treatments of cancer with curative intent. Lung cancer treatments were initially excluded, because the original back-projection dose-reconstruction algorithm uses water-based scatter-correction kernels and therefore does not account for tissue inhomogeneities accurately. The aim of this study was to test a new method, in aqua vivo EPID dosimetry, for fast dose verification of lung cancer irradiations during actual patient treatment. Methods: The key feature of our method is the dose reconstruction in the patient from EPID images, obtained during the actual treatment, whereby the images have been converted to a situation as if the patient consisted entirely of water; hence, the method is termed in aqua vivo. This is done by multiplying the measured in vivo EPID image with the ratio of two digitally reconstructed transmission images for the unit-density and inhomogeneous tissue situation. For dose verification, a comparison is made with the calculated dose distribution with the inhomogeneity correction switched off. IMRT treatment verification is performed for each beam in 2D using a 2D {gamma} evaluation, while for the verification of volumetric-modulated arc therapy (VMAT) treatments in 3D a 3D {gamma} evaluation is applied using the same parameters (3%, 3 mm). The method was tested using two inhomogeneous phantoms simulating a tumor in lung and measuring its sensitivity for patient positioning errors. Subsequently five IMRT and five VMAT clinical lung cancer treatments were investigated, using both the conventional back-projection algorithm and the in aqua vivo method. The verification results of the in aqua vivo method were statistically analyzed for 751 lung cancer patients treated with IMRT and 50 lung cancer patients treated with VMAT. Results: The improvements by

  13. Technical Basis Document for PFP Area Monitoring Dosimetry Program

    CERN Document Server

    Cooper, J R

    2000-01-01

    This document describes the phantom dosimetry used for the PFP Area Monitoring program and establishes the basis for the Plutonium Finishing Plant's (PFP) area monitoring dosimetry program in accordance with the following requirements: Title 10, Code of Federal Regulations (CFR), part 835, ''Occupational Radiation Protection'' Part 835.403; Hanford Site Radiological Control Manual (HSRCM-1), Part 514; HNF-PRO-382, Area Dosimetry Program; and PNL-MA-842, Hanford External Dosimetry Technical Basis Manual.

  14. Dosimetry at a 400 keV accelerator

    DEFF Research Database (Denmark)

    Miller, A.

    1992-01-01

    Absolute calorimetric dosimetry and relative dose mapping methods are described for a 400 keV electron accelerator used for polymer curing and crosslinking experiments. These methods of dosimetry are also useful at accelerators used in gas cleaning processes.......Absolute calorimetric dosimetry and relative dose mapping methods are described for a 400 keV electron accelerator used for polymer curing and crosslinking experiments. These methods of dosimetry are also useful at accelerators used in gas cleaning processes....

  15. Personnel neutron dosimetry at Department of Energy facilities

    Energy Technology Data Exchange (ETDEWEB)

    Brackenbush, L.W.; Endres, G.W.R.; Selby, J.M.; Vallario, E.J.

    1980-08-01

    This study assesses the state of personnel neutron dosimetry at DOE facilities. A survey of the personnel dosimetry systems in use at major DOE facilities was conducted, a literature search was made to determine recent advances in neutron dosimetry, and several dosimetry experts were interviewed. It was concluded that personnel neutron dosimeters do not meet current needs and that serious problems exist now and will increase in the future if neutron quality factors are increased and/or dose limits are lowered.

  16. Revisiting photodynamic therapy dosimetry: reductionist & surrogate approaches to facilitate clinical success

    Science.gov (United States)

    Pogue, Brian W.; Elliott, Jonathan T.; Kanick, Stephen C.; Davis, Scott C.; Samkoe, Kimberley S.; Maytin, Edward V.; Pereira, Stephen P.; Hasan, Tayyaba

    2016-04-01

    Photodynamic therapy (PDT) can be a highly complex treatment, with many parameters influencing treatment efficacy. The extent to which dosimetry is used to monitor and standardize treatment delivery varies widely, ranging from measurement of a single surrogate marker to comprehensive approaches that aim to measure or estimate as many relevant parameters as possible. Today, most clinical PDT treatments are still administered with little more than application of a prescribed drug dose and timed light delivery, and thus the role of patient-specific dosimetry has not reached widespread clinical adoption. This disconnect is at least partly due to the inherent conflict between the need to measure and understand multiple parameters in vivo in order to optimize treatment, and the need for expedience in the clinic and in the regulatory and commercialization process. Thus, a methodical approach to selecting primary dosimetry metrics is required at each stage of translation of a treatment procedure, moving from complex measurements to understand PDT mechanisms in pre-clinical and early phase I trials, towards the identification and application of essential dose-limiting and/or surrogate measurements in phase II/III trials. If successful, identifying the essential and/or reliable surrogate dosimetry measurements should help facilitate increased adoption of clinical PDT. In this paper, examples of essential dosimetry points and surrogate dosimetry tools that may be implemented in phase II/III trials are discussed. For example, the treatment efficacy as limited by light penetration in interstitial PDT may be predicted by the amount of contrast uptake in CT, and so this could be utilized as a surrogate dosimetry measurement to prescribe light doses based upon pre-treatment contrast. Success of clinical ALA-based skin lesion treatment is predicted almost uniquely by the explicit or implicit measurements of photosensitizer and photobleaching, yet the individualization of treatment

  17. Revisiting photodynamic therapy dosimetry: reductionist & surrogate approaches to facilitate clinical success.

    Science.gov (United States)

    Pogue, Brian W; Elliott, Jonathan T; Kanick, Stephen C; Davis, Scott C; Samkoe, Kimberley S; Maytin, Edward V; Pereira, Stephen P; Hasan, Tayyaba

    2016-04-01

    Photodynamic therapy (PDT) can be a highly complex treatment, with many parameters influencing treatment efficacy. The extent to which dosimetry is used to monitor and standardize treatment delivery varies widely, ranging from measurement of a single surrogate marker to comprehensive approaches that aim to measure or estimate as many relevant parameters as possible. Today, most clinical PDT treatments are still administered with little more than application of a prescribed drug dose and timed light delivery, and thus the role of patient-specific dosimetry has not reached widespread clinical adoption. This disconnect is at least partly due to the inherent conflict between the need to measure and understand multiple parameters in vivo in order to optimize treatment, and the need for expedience in the clinic and in the regulatory and commercialization process. Thus, a methodical approach to selecting primary dosimetry metrics is required at each stage of translation of a treatment procedure, moving from complex measurements to understand PDT mechanisms in pre-clinical and early phase I trials, towards the identification and application of essential dose-limiting and/or surrogate measurements in phase II/III trials. If successful, identifying the essential and/or reliable surrogate dosimetry measurements should help facilitate increased adoption of clinical PDT. In this paper, examples of essential dosimetry points and surrogate dosimetry tools that may be implemented in phase II/III trials are discussed. For example, the treatment efficacy as limited by light penetration in interstitial PDT may be predicted by the amount of contrast uptake in CT, and so this could be utilized as a surrogate dosimetry measurement to prescribe light doses based upon pre-treatment contrast. Success of clinical ALA-based skin lesion treatment is predicted almost uniquely by the explicit or implicit measurements of photosensitizer and photobleaching, yet the individualization of treatment

  18. Effect of strategies regarding concentrate supplementation and day-time grazing on N utilization at both field and dairy cow level

    DEFF Research Database (Denmark)

    Lund, Peter; Søegaard, Karen; Weisbjerg, Martin Riis

    2008-01-01

    N utilization at cow and field level was examined over two grazing periods of 30 days with 64 Holstein dairy cows. At cow and field level the effect of sward type (diploid vs. tetraploid perennial ryegrass, both mixed with white clover) and compressed sward height (6 vs. 10 cm) was examined....

  19. Development of tailor-made silica fibres for TL dosimetry

    Science.gov (United States)

    Bradley, D. A.; Abdul Sani, Siti F.; Alalawi, Amani I.; Jafari, S. M.; Noor, Noramaliza M.; Hairul Azhar, A. R.; Mahdiraji, Ghafour Amouzad; Tamchek, Nizam; Ghosh, S.; Paul, M. C.; Alzimami, Khalid S.; Nisbet, A.; Maah, M. J.

    2014-11-01

    The Ge dopant in commercially available silica optical fibres gives rise to appreciable thermoluminscence (TL), weight-for-weight offering sensitivity to MV X-rays several times that of the LiF dosimeter TLD100. The response of these fibres to UV radiation, X-rays, electrons, protons, neutrons and alpha particles, with doses from a fraction of 1 Gy up to 10 kGy, have stimulated further investigation of the magnitude of the TL signal for intrinsic and doped SiO2 fibres. We represent a consortium effort between Malaysian partners and the University of Surrey, aimed at production of silica fibres with specific TL dosimetry applications, utilizing modified chemical vapour deposition (MCVD) doped silica-glass production and fibre-pulling facilities. The work is informed by defect and dopant concentration and various production dependences including pulling parameters such as temperature, speed and tension; the fibres also provide for spatial resolutions down to <10 μm, confronting many limitations faced in use of conventional (TL) dosimetry. Early results are shown for high spatial resolution (~0.1 mm) single-core Ge-doped TL sensors, suited to radiotherapy applications. Preliminary results are also shown for undoped flat optical fibres of mm dimensions and Ge-B doped flat optical fibres of sub-mm dimensions, with potential for measurement of doses in medical diagnostic applications.

  20. Selection of a new dosismetry system: one utility`s experience

    Energy Technology Data Exchange (ETDEWEB)

    Hirning, C.R. [Ontario Hydro, Whitby, ON (Canada). Health Physics Dept.

    1996-12-31

    Ontario Hydro is an electrical utility that operates 20 nuclear reactors of the Candu design. Dosimetry for workers is provided by an in-house thermoluminescence dosimetry service, using two-element dosemeters designed by Atomic Energy of Canada Limited in the late 1960s. Several recent assessments of the dosimetry system have recommended that it be replaced with more up-to-date technology. There has been much interest within the company in the possibility of adopting electronic dosemeters for dosimetry of record. The task of evaluating alternative technologies and recommending the best option for the next dosimetry system was assigned to a team of employees. This team had representation from all of the four nuclear stations, from the two dosimetry laboratories, from the two major labour unions and from the purchasing department. Broad representation was considered necessary to ensure that the interests of all concerned parties would be taken into account. However, the team approach to making such recommendations appears to be uncommon, perhaps even unique. This paper describes the process that was followed by the team, and its outcome. (author).

  1. Dynamic MLC-QA Based On Portal Dosimetry

    Directory of Open Access Journals (Sweden)

    Sajeev Surendran

    2014-05-01

    Full Text Available Purpose: Intensity modulated radiotherapy using dynamic delivery method requires accurate verification of MLC, its position and speed of motion. These parameter have major impact on dose delivery on patients. For quality assurance (QA procedure requires more time consumed in a radiotherapy department. The main purpose of this study was to investigate the potential use of amorphous silicon based EPID portal dosimetry for dMLC QA Methods and Materials: A varian Clinac_iX with On Board Imager (OBI and Rapid Arc facility ( VMAT equipped with 120 leaf Millennium MLC and with Amorphous Silicon Based EPID (aSi-1000, varian mounted on a Exact Robotic Arm is used. The dMLC QA consists of different dynamic MLC pattern provided by varian for checking positional accuracy, MLC gap, Leaf speed and complex dynamic field. Results and Discussion: Various dMLC tests were done using portal dosimetry. All results are within the tolerance limit. Picket fence test shows that leaf position errors of upto 0.2mm can be detected which are within the tolerance limit. Complex dynamic field were exposed to EPID, which shows the leaf speed and are within the tolerance limit.

  2. Validation of internal dosimetry protocols based on stochastic method

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Bruno M.; Fonseca, Telma C.F., E-mail: bmm@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Almeida, Iassudara G.; Trindade, Bruno M.; Campos, Tarcisio P.R., E-mail: tprcampos@yahoo.com.br [Universidade Federal de Minas Gerais (DEN/UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2015-07-01

    Computational phantoms adapted to Monte Carlo codes have been applied successfully in radiation dosimetry fields. NRI research group has been developing Internal Dosimetry Protocols - IDPs, addressing distinct methodologies, software and computational human-simulators, to perform internal dosimetry, especially for new radiopharmaceuticals. Validation of the IDPs is critical to ensure the reliability of the simulations results. Inter comparisons of data from literature with those produced by our IDPs is a suitable method for validation. The aim of this study was to validate the IDPs following such inter comparison procedure. The Golem phantom has been reconfigured to run on MCNP5. The specific absorbed fractions (SAF) for photon at 30, 100 and 1000 keV energies were simulated based on the IDPs and compared with reference values (RV) published by Zankl and Petoussi-Henss, 1998. The SAF average differences from RV and those obtained in IDP simulations was 2.3 %. The SAF largest differences were found in situations involving low energy photons at 30 keV. The Adrenals and thyroid, i.e. the lowest mass organs, had the highest SAF discrepancies towards RV as 7.2 % and 3.8 %, respectively. The statistic differences of SAF applying our IDPs from reference values were considered acceptable at the 30, 100 and 1000 keV spectra. We believe that the main reason for the discrepancies in IDPs run, found in lower masses organs, was due to our source definition methodology. Improvements of source spatial distribution in the voxels may provide outputs more consistent with reference values for lower masses organs. (author)

  3. Instrumentation for the individual dosimetry of workers

    CERN Document Server

    Thévenin, J C

    2003-01-01

    The control of the radiation dose exposure of workers and personnel exposed to ionizing radiations (nuclear industry, nuclear medicine, army, university laboratories etc..) is ensured by individual dosemeters. This dosimetry is mandatory for all workers susceptible to be exposed to more than 30% of the regulatory dose limit. dosemeters are worn on the chest and in some particular cases, on the finger (dosemeter rings) or on the wrist. Passive dosemeters allow to measure the dose a posteriori, while electronic dosemeters allow a direct reading and recording of the dose. This article presents successively: 1 - the general principles of individual dosimetry: situations of exposure, radiation detection, operational data, standardization, calibration and quality assurance, measurement uncertainties; 2 - goals and regulatory framework of individual dosimetry: regulation and recommendations, optimization, respect of dose limits, accidental situations; 3 - passive dosemeters: film, thermoluminescent, radio-photolumin...

  4. Model selection for radiochromic film dosimetry

    CERN Document Server

    Méndez, Ignasi

    2015-01-01

    The purpose of this study was to find the most accurate model for radiochromic film dosimetry by comparing different channel independent perturbation models. A model selection approach based on (algorithmic) information theory was followed, and the results were validated using gamma-index analysis on a set of benchmark test cases. Several questions were addressed: (a) whether incorporating the information of the non-irradiated film, by scanning prior to irradiation, improves the results; (b) whether lateral corrections are necessary when using multichannel models; (c) whether multichannel dosimetry produces better results than single-channel dosimetry; (d) which multichannel perturbation model provides more accurate film doses. It was found that scanning prior to irradiation and applying lateral corrections improved the accuracy of the results. For some perturbation models, increasing the number of color channels did not result in more accurate film doses. Employing Truncated Normal perturbations was found to...

  5. Performance testing of UK personal dosimetry laboratories

    CERN Document Server

    Marshall, T O

    1985-01-01

    The proposed Ionising Radiations Regulations will require all UK personal dosimetry laboratories that monitor classified personnel to be approved for personal dosimetry by the Health and Safety Executive. It is suggested that these approvals should be based on general and supplementary criteria published by the British Calibration Service (BCS) for laboratory approval for the provision of personal dosimetry services. These criteria specify certain qualitative requirements and also indicate the need for regular tests of performance to be carried out to ensure constancy of dosimetric standards. This report concerns the latter. The status of the BCS criteria is discussed and the need for additional documents to cover new techniques and some modifications to existing documents is indicated. A means is described by which the technical performance of laboratories, concerned with personal monitoring for external radiations, can be assessed, both initially and ongoing. The costs to establish the scheme and operate it...

  6. Bayesian Methods for Radiation Detection and Dosimetry

    CERN Document Server

    Groer, Peter G

    2002-01-01

    We performed work in three areas: radiation detection, external and internal radiation dosimetry. In radiation detection we developed Bayesian techniques to estimate the net activity of high and low activity radioactive samples. These techniques have the advantage that the remaining uncertainty about the net activity is described by probability densities. Graphs of the densities show the uncertainty in pictorial form. Figure 1 below demonstrates this point. We applied stochastic processes for a method to obtain Bayesian estimates of 222Rn-daughter products from observed counting rates. In external radiation dosimetry we studied and developed Bayesian methods to estimate radiation doses to an individual with radiation induced chromosome aberrations. We analyzed chromosome aberrations after exposure to gammas and neutrons and developed a method for dose-estimation after criticality accidents. The research in internal radiation dosimetry focused on parameter estimation for compartmental models from observed comp...

  7. Dosimetry procedures for an industrial irradiation plant

    Science.gov (United States)

    Grahn, Ch.

    Accurate and reliable dosimetry procedures constitute a very important part of process control and quality assurance at a radiation processing plant. γ-Dose measurements were made on the GBS 84 irradiator for food and other products on pallets or in containers. Chemical dosimeters wre exposed in the facility under conditions of the typical plant operation. The choice of the dosimeter systems employed was based on the experience in chemical dosimetry gained over several years. Dose uniformity information was obtained in air, spices, bulbs, feeds, cosmetics, plastics and surgical goods. Most products currently irradiated require dose uniformity which can be efficiently provided by pallet or box irradiators like GBS 84. The radiation performance characteristics and some dosimetry procedures are discussed.

  8. Protocol for emergency EPR dosimetry in fingernails.

    Science.gov (United States)

    Trompier, F; Kornak, L; Calas, C; Romanyukha, A; Leblanc, B; Mitchell, C A; Swartz, H M; Clairand, I

    2007-08-01

    There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried out on nails freshly sampled and irradiated to 4 and 20 Gy; this protocol gave dose estimates with an error of less than 30%.

  9. State of the art of solid state dosimetry; Estado da arte em dosimetria do estado solido

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Susana O., E-mail: sosouza@ufs.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil); Yamamoto, Takayoshi [Radioisotope Research Center, Osaka University (Japan); D' Errico, Francesco, E-mail: francesco.derrico@yale.edu [Yale University, School of Medicine, CT (United States)

    2014-07-01

    Passive solid-state detectors still dominate the personal dosimetry field. This article provides state of the art in this field and summarizes the most recent works presented on TL, OSL and RPL during the 17th International Conference on Solid State Dosimetry held in Recife in September 2013. The Article contains in particular the techniques Thermoluminescence (TL), Optically Stimulated Luminescence (OSL), radio photoluminescence (RPL). Thermoluminescence has the biggest advantage of the wide availability of commercial materials for dosimetry, and the nature tissue-equivalent of several of these materials. The limitation of the TL dosimetry presents fading luminance signal and the need for high temperatures to obtain the signal. The Optically Stimulated Luminescence has the advantages of high sensitivity, the possibility of multiple reading, while its limit is the need to use response compensating filters in addition to the high cost of equipment and dosimeters still restricted very few options trading . The radio photoluminescence has a reading that is completely non-destructive, but their dosimeters present lack of tissue-equivalent and a high cost. Presents the details of the techniques and the advantages and limitations of each of these will be discussed.

  10. Development of gas microstrip detectors for digital x-ray imaging and radiation dosimetry

    CERN Document Server

    Dixit, M S; Dubeau, J; Gobbi, D G; Johns, P C; Karlen, Dean A; Oakham, F G; Waker, A J

    1998-01-01

    Our recent work in the application of gas microstrip detector (GMD) technology to the fields of digital X-ray imaging and radiation dosimetry Is described. The GMD can measure the position and the energy of individual photons at the high counting rates encountered in X-ray imaging. GMD-based imaging systems have high detective quantum efficiency and permit improvement of image quality and contrast using display windowing and measured energy information. Results are presented on the performance of a prototype GMD imaging system operated with a xenon/methane 90/10 gas mixture at 1 atm. Results are also presented on the performance of a GMD filled with tissue equivalent gases for applications in the field of radiation dosimetry in mixed neutron and gamma fields. The results show that the GMD can be used for dosimetric discrimination between different types of radiation in mixed-field environments.

  11. Pre-evaluation of an ionization chamber for clinical radiotherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Lucio P.; Perini, Ana P.; Xavier, Marcos; Caldas, Linda V.E., E-mail: mxavier@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-07-01

    This work presents some pre-operational tests for characterization of a new homemade ionization chamber developed at the Calibration Laboratory of Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP). This chamber was designed for use in radiotherapy dosimetry. To study the utilization of this chamber in radiotherapy, some tests were undertaken: short- and medium-term stabilities, saturation curve, recombination loss, polarity effect and leakage current. All results obtained in these tests were within the international recommendations. (author)

  12. Design of a Class of Antennas Utilizing MEMS, EBG and Septum Polarizers including Near-field Coupling Analysis

    Science.gov (United States)

    Kim, Ilkyu

    Recent developments in mobile communications have led to an increased appearance of short-range communications and high data-rate signal transmission. New technologies provides the need for an accurate near-field coupling analysis and novel antenna designs. An ability to effectively estimate the coupling within the near-field region is required to realize short-range communications. Currently, two common techniques that are applicable to the near-field coupling problem are 1) integral form of coupling formula and 2) generalized Friis formula. These formulas are investigated with an emphasis on straightforward calculation and accuracy for various distances between the two antennas. The coupling formulas are computed for a variety of antennas, and several antenna configurations are evaluated through full-wave simulation and indoor measurement in order to validate these techniques. In addition, this research aims to design multi-functional and high performance antennas based on MEMS (Microelectromechanical Systems) switches, EBG (Electromagnetic Bandgap) structures, and septum polarizers. A MEMS switch is incorporated into a slot loaded patch antenna to attain frequency reconfigurability. The resonant frequency of the patch antenna can be shifted using the MEM switch, which is actuated by the integrated bias networks. Furthermore, a high gain base-station antenna utilizing beam-tilting is designed to maximize gain for tilted beam applications. To realize this base-station antenna, an array of four dipole-EBG elements is constructed to implement a fixed down-tilt main beam with application in base station arrays. An improvement of the operating range with the EBG-dipole array is evaluated using a simple linkbudget analysis. The septum polarizer has been widely used in circularly polarized antenna systems due to its simple and compact design and high quality of circularity. In this research, the sigmoid function is used to smoothen the edge in the septum design, which

  13. Technical basis for internal dosimetry at Hanford

    Energy Technology Data Exchange (ETDEWEB)

    Sula, M.J.; Carbaugh, E.H.; Bihl, D.E.

    1991-07-01

    The Hanford Internal Dosimetry Program, administered by Pacific Northwest Laboratory for the US Department of Energy, provides routine bioassay monitoring for employees who are potentially exposed to radionuclides in the workplace. This report presents the technical basis for routine bioassay monitoring and the assessment of internal dose at Hanford. The radionuclides of concern include tritium, corrosion products ({sup 58}Co, {sup 60}Co, {sup 54}Mn, and {sup 59}Fe), strontium, cesium, iodine, europium, uranium, plutonium, and americium,. Sections on each of these radionuclides discuss the sources and characteristics; dosimetry; bioassay measurements and monitoring; dose measurement, assessment, and mitigation and bioassay follow-up treatment. 78 refs., 35 figs., 115 tabs.

  14. Technical basis for internal dosimetry at Hanford

    Energy Technology Data Exchange (ETDEWEB)

    Sula, M.J.; Carbaugh, E.H.; Bihl, D.E.

    1989-04-01

    The Hanford Internal Dosimetry Program, administered by Pacific Northwest Laboratory for the US Department of Energy, provides routine bioassay monitoring for employees who are potentially exposed to radionuclides in the workplace. This report presents the technical basis for routine bioassay monitoring and the assessment of internal dose at Hanford. The radionuclides of concern include tritium, corrosion products (/sup 58/Co, /sup 60/Co, /sup 54/Mn, and /sup 59/Fe), strontium, cesium, iodine, europium, uranium, plutonium, and americium. Sections on each of these radionuclides discuss the sources and characteristics; dosimetry; bioassay measurements and monitoring; dose measurement, assessment, and mitigation; and bioassay follow-up treatment. 64 refs., 42 figs., 118 tabs.

  15. Optically stimulated luminescence in retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Murray, A.S.

    2002-01-01

    Since the beginning of the 1990s the exploration of optically stimulated luminescence (OSL) in retrospective accident dosimetry has driven an intensive investigation and development programme at Riso into measurement facilities and techniques. This paper reviews some of the outcomes of this progr......Since the beginning of the 1990s the exploration of optically stimulated luminescence (OSL) in retrospective accident dosimetry has driven an intensive investigation and development programme at Riso into measurement facilities and techniques. This paper reviews some of the outcomes...

  16. SNL RML recommended dosimetry cross section compendium

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, P.J.; Kelly, J.G.; Luera, T.F. [Sandia National Labs., Albuquerque, NM (United States); VanDenburg, J. [Science and Engineering Associates, Inc., Albuquerque, NM (United States)

    1993-11-01

    A compendium of dosimetry cross sections is presented for use in the characterization of fission reactor spectrum and fluence. The contents of this cross section library are based upon the ENDF/B-VI and IRDF-90 cross section libraries and are recommended as a replacement for the DOSCROS84 multigroup library that is widely used by the dosimetry community. Documentation is provided on the rationale for the choice of the cross sections selected for inclusion in this library and on the uncertainty and variation in cross sections presented by state-of-the-art evaluations.

  17. How flatbed scanners upset accurate film dosimetry.

    Science.gov (United States)

    van Battum, L J; Huizenga, H; Verdaasdonk, R M; Heukelom, S

    2016-01-21

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner's transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner's optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film.

  18. Evaluation of triple channel correction acquisition method for radiochromic film dosimetry

    OpenAIRE

    2012-01-01

    The purpose of this study was to evaluate the triple channel correction acquisition (TCCA) method for radiochromic film dosimetry performed with a flatbed scanner. The study had two parts: a fundamental and a clinical examination. In the fundamental examination, we evaluated the accuracy of calibration curves for Gafchromic EBT2 (EBT2). The films were calibrated using a field-by-field method with 13 dose steps. Seven calibration curves obtained by TCCA were compared with those produced by a s...

  19. Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy

    Science.gov (United States)

    Glaser, Adam Kenneth

    Since its discovery in the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams. To advance this application, several novel techniques were implemented to realize the maximum potential of the signal, such as time-gating for maximizing the signal to noise ratio (SNR) and Cherenkov-excited fluorescence for generating isotropic light release in water. Proof of concept experiments were conducted in water tanks to demonstrate the feasibility of the proposed method for two-dimensional (2D) projection imaging, three-dimensional (3D) parallel beam tomography, large field of view 3D cone beam tomography, and video-rate dynamic imaging of treatment plans for a number of common radiotherapy applications. The proposed dosimetry method was found to have a number of unique advantages, including but not limited to its non-invasive nature, water-equivalence, speed, high-resolution, ability to provide full 3D data, and potential to yield data in-vivo. Based on

  20. Thermoluminescent dosimetry in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lara C, A.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Av. Legaria 694, Col. Irrigacion, 11500 Ciudad de Mexico (Mexico); Osorio V, M. [ISSSTE, Centro Medico Nacional 20 de Noviembre, Felix Cuevas 540, Col. del Valle, 03100 Ciudad de Mexico (Mexico); Hernandez O, O., E-mail: armando_lara_cam@yahoo.com.mx [Hospital General de Mexico, Dr. Balmis 148, Col. Doctores, 06726 Ciudad de Mexico (Mexico)

    2016-10-15

    In this work we studied the dosimetry performed on CT scan in two different equipment, SOMATOM and Phillips, with 16 and 64 slice respectively. We used 51 pellets of lithium fluoride doped with magnesium and titanium (LiF: Mg, Ti) also knows as TLD-100 due to its physical properties and its easy of use, in this study, first analysis a batch of 56 pellets, but only 53 pellets were optimal for this study, cesium-137 was used as source irradiation, then proceeded to calibrate the batch with X-rays source, measuring the corresponding dose in a Farmers ionization chamber, then, we obtained a calibration curve, and we used as reference to calculation of the applied dose, finally designing ergonomic mesh, were it was deposited a TLD 100, placed in a regions of interest were made to each scan type. Once characterized our material proceeded to testing in 30 patients, which were irradiated with X-ray tube, whose operation was performed at 80, 120 kV with a current of 100, 300 and 400 m A according to scanning protocol. Overall we measured dose of 5 mGy to 53 mGy, these measurements reflect significant dose to can induced cancer, due previous reports published, that doses greater than 20 mGy there is a risk of developing cancer in the long term, but in practice when it assigned a medical diagnosis, there are no dose limits due to benefits patients, however, IAEA publish recommendations that allow us to carry out optimum handling of ionizing radiation, among these is the quality control of the tomography equipment that helps greatly reduce patient dose. (Author)

  1. Kinetics model for lutate dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lima, M.F.; Mesquita, C.H., E-mail: mflima@ipen.br, E-mail: chmesqui@ipen.br [Instituto de Pesquisas Energeticas (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-11-01

    The use of compartmental analysis to predict the behavior of drugs in the organism is considered the better option among numerous methods employed in pharmacodynamics. A six compartments model was developed to determinate the kinetic constants of 177Lu-DOTATATO biodistribution using data from one published study with 67 patients treated by PRRT (Peptide receptor radionuclide therapy) and followed by CT during 68,25 hours. The compartmental analysis was made using the software AnaComp Registered-Sign . The influence of the time pos-injection over the dose assessment was studied taking into account the renal excretion management by aminoacid coinfusion, whose direct effects persist in the first day. The biodistribution curve was split in five sectors: 0-0.25h; 0-3.25h; 3.25-24.25h; 24.25-68.25h and 3.25-68.25h. After the examination of that influence, the study was concentrated in separate the biodistribution curve in two phases. Phase 1: governed by uptake from the blood, considering the time pos-injection until 3.25h and phase 2: governed by renal excretion, considering the time pos-injection from 3.25h to 68.25h. The model considered the organs and tissues superposition in the CT image acquisition by sampling parameters as the contribution of the the activity concentration in blood and relation between the sizes of the whole body and measured organs. The kinetic constants obtained from each phase (1 and 2) were used in dose assessment to patients in 26 organs and tissues described by MIRD. Dosimetry results were in agreement with the available results from literature, restrict to whole body, kidneys, bone marrow, spleen and liver. The advantage of the proposed model is the compartmental method quickness and power to estimate dose in organs and tissues, including tumor that, in the most part, were not discriminate by voxels of phantoms built using CT images. (author)

  2. SEVENTH DOE WORKSHOP ON PERSONNEL NEUTRON DOSIMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Vallario, E J

    1978-10-24

    This workshop was the seventh of a series and was held on October 23-24. 1978, at the Central Electricity Generating Board, HQ, London, England. Typically~ attendees at the Workshop were concerned with one of three activities: studying and refining existing techniques in an attempt to quantify already-known parameters with greater precision, looking for ways to apply existing neutron dosirr:etry techniques to a specific local problem, identifying the needs and weaknesses of existing systems, with the goal of improving and passibly simplifying field measurements. The types of neutron dosimetry techniques discussed by participants included albedo dosimeters, track etch, and TLD. One speaker reported on NTA film, noting that fading could be eliminated by drying the emulsion in dry nitrogen before field use. There were no reports on tissue equivalent proportional counters or activation analysis. One participant discussed a metal oxide silicon dosimeter. The need to develop a consistent standard terminology, as well as calibration sources and techniques, on both the national and international level was evident. The need for standardization is particularly acute in the U.S. Techniques for evaluating dosimeter response in the field should he standardized, since several different instruments with widely different response characteristics are currently being used. The choice of instruments is often parochial. Also. the type and use of phantoms should be standardized. Neutron dose assignment is significantly affected by the position of the dosimeter on the body. for example, a typical albedo dosimeter may give differences of up to 20% depending on whether it is worn on the belt or chest. Larger errors are encountered with front-to-back (angular} orientation. 1n an attempt to minimize such errors~ at least two European facilities are using neutron dosimeter belts, which provide dosimeters both in front and in back of the wearer. The gamma-to-neutron ratio around nuclear power

  3. Assessment of a 2D electronic portal imaging devices-based dosimetry algorithm for pretreatment and in-vivo midplane dose verification

    Directory of Open Access Journals (Sweden)

    Ali Jomehzadeh

    2016-01-01

    Conclusion: The 2D EPID-based dosimetry algorithm provides an accurate method to verify the dose of a simple 10 × 10 cm2 field, in two dimensions, inside a homogenous slab phantom and an IMRT prostate plan, as well as in 3D conformal plans (prostate, head-and-neck, and lung plans applied using an anthropomorphic phantom and in vivo. However, further investigation to improve the 2D EPID dosimetry algorithm for a head-and-neck case, is necessary.

  4. Recombination methods in the dosimetry of mixed radiation

    Energy Technology Data Exchange (ETDEWEB)

    Golnik, N. [Institute of Atomic Energy, Otwock-Swierk (Poland)

    1996-12-31

    The work describes the state of art of recombination methods developed for the dosimetry of mixed radiation fields. The existing theories of initial recombination of ions in gases is given. Recombination methods developed in IAE are reviewed in detail. The methods described here can be applied in mixed radiation fields of poorly known composition and practically unlimited energy range. Main dosimetric parameters such as absorbed dose, photon component to the absorbed dose, radiation quality factor, dose equivalent, ambient dose equivalent and some other quantities can be determined in single instrument. A novel method has been developed for determination of the energy loss distribution in the nanometric region. Experimental tests showed that the method is promising not only for radiation protection but also for radiobiological investigations. (author). 166 refs, 62 figs, 16 tabs.

  5. Relative electron dosimetry using a synthetic diamond probe

    CERN Document Server

    Merwe, D G

    1999-01-01

    Implementation of Bragg-Gray Cavity Theory in electron dosimetry is complicated by the fact that most commercial detector volumes behave as small field inhomogeneities. Several correction factors are necessary to establish the absorbed dose at a particular point in a homogenous tissue-equivalent phantom. The energy dependence of air and the replacement effects introduced as a result of air ionization chambers' construction and size, increase the uncertainty of electron beam calibrations. Preliminary relative dose measurements performed with a prototype synthetic diamond are presented here. Theoretically, the radiation response of diamond, synthetic or natural, has negligible energy dependence. The sensitivity and small size of the probe makes it an excellent candidate for measurements in fields of high dose gradient.

  6. Implications of in vitro dosimetry on toxicological ranking of low aspect ratio engineered nanomaterials.

    Science.gov (United States)

    Pal, Anoop K; Bello, Dhimiter; Cohen, Joel; Demokritou, Philip

    2015-01-01

    In vitro high throughput screening platforms based on mechanistic injury pathways are been used for hazard assessment of engineered nanomaterials (ENM). Toxicity screening and other in vitro nanotoxicology assessment efforts in essence compare and rank nanomaterials relative to each other. We hypothesize that this ranking of ENM is susceptible to dispersion and dosimetry protocols, which continue to be poorly standardized. Our objective was to quantitate the impact of dosimetry on toxicity ranking of ENM. A set of eight well-characterized and diverse low aspect ratio ENMs, were utilized. The recently developed in vitro dosimetry platform at Harvard, which includes preparation of fairly monodispersed suspensions, measurement of the effective density of formed agglomerates in culture media and fate and transport modeling was used for calculating the effective dose delivered to cells as a function of time. Changes in the dose-response relationships between the administered and delivered dose were investigated with two representative endpoints, cell viability and IL-8 production, in the human monocytic THP-1 cells. The slopes of administered/delivered dose-response relationships changed 1:4.94 times and were ENM-dependent. The overall relative ranking of ENM intrinsic toxicity also changed considerably, matching notably better the in vivo inflammation data (R(2 )= 0.97 versus 0.64). This standardized dispersion and dosimetry methodology presented here is generalizable to low aspect ratio ENMs. Our findings further reinforce the need to reanalyze and reinterpret in vitro ENM hazard ranking data published in the nanotoxicology literature in the light of dispersion and dosimetry considerations (or lack thereof) and to adopt these protocols in future in vitro nanotoxicology testing.

  7. Dosimetry implant for treating restenosis and hyperplasia

    Science.gov (United States)

    Srivastava, Suresh; Gonzales, Gilbert R; Howell, Roger W; Bolch, Wesley E; Adzic, Radoslav

    2014-09-16

    The present invention discloses a method of selectively providing radiation dosimetry to a subject in need of such treatment. The radiation is applied by an implant comprising a body member and .sup.117mSn electroplated at selected locations of the body member, emitting conversion electrons absorbed immediately adjacent selected locations while not affecting surrounding tissue outside of the immediately adjacent area.

  8. Optically stimulated luminescence techniques in retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Murray, A.S.

    2001-01-01

    Optically stimulated luminescence signals from natural quartz and feldspar are now used routinely in dating geological and archaeological materials. More recently they have also been employed in accident dosimetry, i.e. the retrospective assessment of doses received as a result of a nuclear...

  9. Development of A-bomb survivor dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, G.D.

    1995-12-31

    An all important datum in risk assessment is the radiation dose to individual survivors of the bombings in Hiroshima and Nagasaki. The first set of dose estimates for survivors was based on a dosimetry system developed in 1957 by the Oak Ridge National Laboratory (ORNL). These Tentative 1957 Doses (T57D) were later replaced by a more extensive and refined set of Tentative 1965 Doses (T65D). The T65D system of dose estimation for survivors was also developed at ORNL and served as a basis for risk assessment throughout the 1970s. In the late 1970s, it was suggested that there were serious inadequacies with the T65D system, and these inadequacies were the topic of discussion at two symposia held in 1981. In early 1983, joint US- Japan research programs were established to conduct a thorough review of all aspects of the radiation dosimetry for the Hiroshima and Nagasaki A-bomb survivors. A number of important contributions to this review were made by ORNL staff members. The review was completed in 1986 and a new Dosimetry System 1986 (DS86) was adopted for use. This paper discusses the development of the various systems of A-bomb survivor dosimetry, and the status of the current DS86 system as it is being applied in the medical follow-up studies of the A-bomb survivors and their offspring.

  10. Thermoluminescence Dosimetry Applied to Radiation Protection

    DEFF Research Database (Denmark)

    Christensen, Poul; Bøtter-Jensen, Lars; Majborn, Benny

    1982-01-01

    This is a general review of the present state of the development and application of thermoluminescence dosimetry (TLD) for radiation protection purposes. A description is given of commonly used thermoluminescent dosimeters and their main dosimetric properties, e.g. energy response, dose range...

  11. Dosimetry implant for treating restenosis and hyperplasia

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Suresh; Gonzales, Gilbert R; Howell, Roger W; Bolch, Wesley E; Adzic, Radoslav

    2014-09-16

    The present invention discloses a method of selectively providing radiation dosimetry to a subject in need of such treatment. The radiation is applied by an implant comprising a body member and .sup.117mSn electroplated at selected locations of the body member, emitting conversion electrons absorbed immediately adjacent selected locations while not affecting surrounding tissue outside of the immediately adjacent area.

  12. Intra-Operative Dosimetry in Prostate Brachytherapy

    Science.gov (United States)

    2007-11-01

    CT-based post-implant dosimetry. Figure 1: System concept for TRUS and C-arm fusion B BODY B.1 Brief System Concept The system concept for...C-arm calibration - is it really necessary?,” MICCAI, pp. 639–646, 2005. 10. Brainlab, Inc., Heimstetten, Germany, Vector Vision. 11. Medtronic

  13. Advances in reference and transfer dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Desrosiers, M.F. [Ionizing Radiation Division, Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    1999-07-01

    All prerequisites are now in place to create a fundamentally and radically different type of calibration service for the radiation processing industry. Advancements in dosimetry and information technology can be combined to provide industry with on-line calibrations, on demand at a low cost. The remote calibration service will serve as a basis for other areas of metrology. (Author)

  14. Personnel radiation dosimetry symposium: program and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    1984-10-01

    The purpose was to provide applied and research dosimetrists with sufficient information to evaluate the status and direction of their programs relative to the latest guidelines and techniques. A technical program was presented concerning experience, requirements, and advances in gamma, beta, and neutron personnel dosimetry.

  15. Evaluation of correlation between chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation.

    Science.gov (United States)

    Hasanzadeh, Hadi; Mokhtari-Dizaji, Manijhe; Bathaie, S Zahra; Hassan, Zuhair M

    2010-06-01

    Currently several therapeutic applications of ultrasound in cancer treatment are under progress which uses cavitation phenomena to deliver their effects. There are several methods to evaluate cavitation activity such as chemical dosimetry and measurement of subharmonic signals. In this study, the cavitation activity induced by the ultrasound irradiation on exposure parameters has been measured by terephthalic acid chemical dosimetry and subharmonic analysis. Experiments were performed in the near 1 MHz fields in the progressive wave mode and effect of duty cycles changes with 2 W/cm(2) intensity (I(SATA)) and acoustic intensity changes in continuous mode on both fluorescence intensity and subharmonic intensity were measured. The dependence between fluorescence intensity of terephthalic acid chemical dosimetry and subharmonic intensity analysis were analyzed by Pearson correlation (p-value subharmonic intensity and the fluorescence intensity for continuous mode is higher than for pulsing mode (p-value subharmonic intensity and the fluorescence intensity with sonication intensity (p-value subharmonic intensity at different duty cycles (R=0.997, p-value subharmonic intensity (microW/cm(2)) significantly correlated with the fluorescence intensity (count) (R=0.901; psubharmonic intensity due to subharmonic spectrum analysis. It is concluded that there is dependence between terephthalic acid chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation activity.

  16. Environmental impact assessment of wood ash utilization in forest road construction and maintenance--A field study.

    Science.gov (United States)

    Oburger, Eva; Jäger, Anna; Pasch, Alexander; Dellantonio, Alex; Stampfer, Karl; Wenzel, Walter W

    2016-02-15

    The ever increasing use of wood material as fuel for green energy production requires innovative, environmentally safe strategies for recycling of the remaining wood ash. Utilizing wood ash in forest road construction and maintenance to improve mechanical stability has been suggested as a feasible recycling option. To investigate the environmental impact of wood ash application in forest road maintenance, a two-year field experiment was conducted at two Austrian forest sites (Kobernausserwald (KO) (soil pH 5.5) and Weyregg (WE) (pH 7.7)) differing in their soil chemical properties. Two different ashes, one produced by grate incineration (GA) and the other by fluidized bed incineration in a mixture with 15 vol% burnt lime (FBA), were incorporated in repeated road sections at a 15:85% (V/V) ash-to-soil rate. Leaching waters from the road body were collected and analyzed for 32 environmentally relevant parameters over two years. Upon termination of the experiment, sub-road soil samples were collected and analyzed for ash-related changes in soil chemistry. Even though a larger number of parameters was affected by the ash application at the alkaline site (WE), we observed the most pronounced initial increases of pH as well as Al, As, Fe, Mn, Ni, Co, Cu, Mo, and NO2(−) concentrations in leachates beneath GA-treated road bodies at Kobernausserwald due to the lower soil buffer capacity at this site. Despite the observed effects our results indicate that, when specific requirements are met (i.e. appropriate ash quality, sufficient soil buffer capacity below the road body, and single time-point ash incorporation within several decades), wood ash application in forest road construction is generally environmentally acceptable.

  17. Pulse-resolved radiotherapy dosimetry using fiber-coupled organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Ravnsborg Beierholm, A.

    2011-05-15

    This PhD project pertains to the development and adaptation of a dosimetry system that can be used to verify the delivery of radiation in modern radiotherapy modalities involving small radiation fields and dynamic radiation delivery. The dosimetry system is based on fibre-coupled organic scintillators and can be perceived as a well characterized, independent alternative to the methods that are in clinical use today. The dosimeter itself does not require a voltage supply, and is composed of water equivalent materials. The dosimeter can be fabricated with a sensitive volume smaller than a cubic millimeter, which is small enough to resolve the small radiation fields encountered in modern radiotherapy. The fast readout of the dosimeter enables measurements on the same time scale as the pulsed radiation delivery from the medical linear accelerators used for treatment. The dosimetry system, comprising fiber-coupled organic scintillators and data acquisition hardware, was developed at the Radiation Research Division at Risoe DTU and tested using clinical x-ray beams at hospitals in Denmark and abroad. Measurements of output factors and percentage depth dose were performed and compared with reference values and Monte Carlo simulations for static square radiation fields for standard (4 cm x 4 cm to 20 cm x 20 cm) and small (down to 0.6 cm x 0.6 cm) field sizes. The accuracy of most of the obtained measurements was good, agreeing with reference and simulated dose values to within 2 % standard deviation for both standard and small fields. This thesis concludes that the new pulse-resolved dosimetry system holds great potential for modern radiotherapy applications, such as stereotactic radiotherapy and intensity-modulated radiotherapy. (Author)

  18. Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Matthews, Q [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Hilts, M [Medical Physics, BC Cancer Agency-Vancouver Island Centre, Victoria BC V8R 6V5 (Canada); Schulze, G [Michael Smith Laboratories, University of British Columbia, Vancouver BC V6T 1Z4 (Canada); Blades, M W [Department of Chemistry, University of British Columbia, Vancouver BC V6T 1Z1 (Canada); Turner, R F B [Michael Smith Laboratories, University of British Columbia, Vancouver BC V6T 1Z4 (Canada); Department of Chemistry, University of British Columbia, Vancouver BC V6T 1Z1 (Canada); Department of Electrical and Computer Engineering, University of British Columbia, Vancouver BC V6T 1Z4 (Canada)

    2006-05-21

    This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors >15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data.

  19. Investigation of a 2D two-point maximum entropy regularization method for signal-to-noise ratio enhancement: application to CT polymer gel dosimetry.

    Science.gov (United States)

    Jirasek, A; Matthews, Q; Hilts, M; Schulze, G; Blades, M W; Turner, R F B

    2006-05-21

    This study presents a new method of image signal-to-noise ratio (SNR) enhancement by utilizing a newly developed 2D two-point maximum entropy regularization method (TPMEM). When utilized as an image filter, it is shown that 2D TPMEM offers unsurpassed flexibility in its ability to balance the complementary requirements of image smoothness and fidelity. The technique is evaluated for use in the enhancement of x-ray computed tomography (CT) images of irradiated polymer gels used in radiation dosimetry. We utilize a range of statistical parameters (e.g. root-mean square error, correlation coefficient, error histograms, Fourier data) to characterize the performance of TPMEM applied to a series of synthetic images of varying initial SNR. These images are designed to mimic a range of dose intensity patterns that would occur in x-ray CT polymer gel radiation dosimetry. Analysis is extended to a CT image of a polymer gel dosimeter irradiated with a stereotactic radiation therapy dose distribution. Results indicate that TPMEM performs strikingly well on radiation dosimetry data, significantly enhancing the SNR of noise-corrupted images (SNR enhancement factors >15 are possible) while minimally distorting the original image detail (as shown by the error histograms and Fourier data). It is also noted that application of this new TPMEM filter is not restricted exclusively to x-ray CT polymer gel dosimetry image data but can in future be extended to a wide range of radiation dosimetry data.

  20. In vivo thermoluminescent dosimetry in studies of helicoid computed tomography and excretory urogram; Dosimetria termoluminiscente In vivo en estudios de tomografia computada helicoidal y urograma excretor

    Energy Technology Data Exchange (ETDEWEB)

    Cruz C, D.; Azorin N, J. [UAM-I, 09340 Mexico D.F. (Mexico); Saucedo A, V.M.; Barajas O, J.L. [Unidad de Especialidades Medicas, Secretaria de la Defensa Nacional, 11500 Mexico D.F. (Mexico)

    2005-07-01

    The dosimetry is the field of measurement of the ionizing radiations. It final objective is to determine the 'absorbed dose' for people. The dosimetry is vital in the radiotherapy, the radiological protection and the treatment technologies by irradiation. Presently work, we develop 'In vivo' dosimetry, in exposed patients to studies of helical computed tomography and excretory urogram. The dosimetry 'in vivo' was carried out in 20 patients selected aleatorily, for each medical study. The absorbed dose was measured in points of interest located in crystalline, thyroid, chest and abdomen of each patient, by means of thermoluminescent dosemeters (TLD) LiF: Mg,Cu,P + Ptfe of national fabrication. Also it was quantified the dose in the working area. (Author)

  1. Synthesis of the scientific French speaking days on numerical codes in radiation protection, in radio physics and in dosimetry; Synthese des journees scientifiques francophones portant sur les codes de calculs en radioprotection, radiophysique et dosimetrie

    Energy Technology Data Exchange (ETDEWEB)

    Paul, D. [Universite de la Mediterranee, Faculte de Pharmacie, Service de Medecine et Sante au Travail, Lab. de Biogenotoxicologie et Mutagenese Environnement (EA 1784-IFR PMSE 112), 13 - Marseille (France); Makovicka, L. [Centre National de la Recherche Scientifique (CNRS), RMA/CREST/FEMTO-ST, UMR 6174, 25 - Montbeliard (France); Ricard, M. [Institut Gustave Roussy, Service de Physique, 94 - Villejuif (France)

    2005-03-01

    Synthesis of the scientific French speaking days on numerical codes in radiation protection, in radio-physics and in dosimetry. The paper carries the title of 'French speaking' scientific days co-organized on October 2-3, 2003 in Sochaux by the SFRP, SFPM and FIRAM societies. It has for objective to establish the scientific balance sheet of this international event, to give the synthesis of current tendencies in the field of the development and of the use of the numerical codes in radiation protection, in radio-physics and in dosimetry. (author)

  2. Development of radiation biological dosimetry and treatment of radiation-induced damaged tissue

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chul Koo; Kim, Tae Hwan; Lee, Yun Sil [and others

    2000-04-01

    Util now, only a few methods have been developed for radiation biological dosimetry such as conventional chromosome aberration and micronucleus in peripheral blood cell. However, because these methods not only can be estimated by the expert, but also have a little limitation due to need high technique and many times in the case of radiation accident, it is very difficult to evaluate the absorbed dose of victims. Therefore, we should develop effective, easy, simple and rapid biodosimetry and its guideline(triage) to be able to be treated the victims as fast as possible. We established the apoptotic fragment assay, PCC, comet assay, and micronucleus assay which was the significant relationship between dose and cell damages to evaluate the irradiated dose as correct and rapid as possible using lymphocytes and crypt cells, and compared with chromosome dosimetry and micronucleus assay.

  3. Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources

    Science.gov (United States)

    Rivard, Mark Joseph

    Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source

  4. Thermoluminescence in medical dosimetry; Termoluminiscencia en dosimetria medica

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, T., E-mail: trivera@ipn.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)

    2011-10-15

    The dosimetry by thermoluminescence (Tl) is applied in the entire world for the dosimetry of ionizing radiations specially to personal and medical dosimetry. This dosimetry method has been very interesting for measures in vivo because the Tl dosimeters have the advantage of being very sensitive in a very small volume and they are also equivalent to tissue and they do not need additional accessories (for example, cable, electrometer, etc.) The main characteristics of the diverse Tl materials to be used in the radiation measures and practical applications are: the Tl curve, the share homogeneity, the signal stability after the irradiation, precision and exactitude, the response in function with the dose and the energy influence. In this work a brief summary of the advances of the radiations dosimetry is presented by means of the thermally stimulated luminescence and its application to the dosimetry in radiotherapy. (Author)

  5. Design of a realistic radiation field for the calibration of dosimeters used in interventional radiology cardiology (medical personnel dosimetry); Conception d'un champ de rayonnements realiste pour l'etalonnage des dosimetres utilises en radiologie cardiologie interventionnelle (dosimetrie du personnel medical)

    Energy Technology Data Exchange (ETDEWEB)

    Bordy, J.M.; Daures, J.; Denoziere, M.; Gouriou, J. [CEA Saclay, LIST, Laboratoire National Henri Becquerel, 91 - Gif-sur-Yvette (France); Itie, Ch.; Donadile, L. [Institut de Radioprotection et de Surete Nucleaire (IRSN), 92263 Fontenay-aux-Roses (France); Struelens, L. [Belgian Nuclear Research Centre (SCK.CEN) (Belgium); Schultz, F. [Delft University of Technology, Applied Physics-RRR-RIH, Pays Bas (Netherlands)

    2010-07-01

    The authors present the principle to determine the reference value in terms of individual dose equivalent for a calibration installation specifically designed to emulate a radiation field faced at a workstation during interventional cardiology or radiology. They present the workstation configuration which includes the patient and the surgeon. They report the study of the calibration installation where the patient and surgeon are replaced by 'phantoms', and indicate the various fluence spectra obtained at different locations corresponding to different parts of the human body. They compare the simulated and measured spectra

  6. Trends in Radiation Dosimetry: preliminary overview of active growth areas, research trends and hot topics from 2011-2015

    Science.gov (United States)

    Baldock, C.

    2017-01-01

    The themes and trends of the radiation dosimetry research field were bibliometrically explored by way of co-occurrence term maps using the titles and abstracts text corpora from the Web of Science database for the period from 2011 to 2015. Visualisation of similarities was used by way of the VOSviewer visualization tool to generate cluster maps of radiation dosimetry knowledge domains and the associated citation impact of topics within the domains. Heat maps were then generated to assist in the understanding of active growth areas, research trends, and emerging and hot topics.

  7. TU-F-201-00: Radiochromic Film Dosimetry Update

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-06-15

    Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to) external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.

  8. Intercomparison of passive dosimetry technology at EDF facilities in France.

    Science.gov (United States)

    Garcier, Y; Cordier, G; Pauron, C; Fazileabasse, J

    2007-01-01

    Since the spring of 1999, new French radiation protection legislation has allowed the use of passive dosemeters, other than the silver emulsion film badge, for the measurement of H(p)(10). Faced with the eventual obsolescence of its dosimetry system, Electricité de France (EDF, the French electricity provider) initiated a comparative study of passive dosemeters, based on different technologies, that had received accreditation by national laboratories and regulatory bodies, namely: TLD, RPL and OSL. An extended field study in nuclear power stations and medical X-ray departments has shown that all technologies provide compatible dosimetric estimates. It also showed that the selected dosemeters based on RPL and OSL technologies gave better results due to their energy responses and to a lower detection threshold compliant with the new regulation. A final suggestion to implement a new OSL based dosimetric system is made due to its overall performance and to its lower cost of implementation.

  9. Photon and fast neutron dosimetry using aluminium oxide thermoluminescence dosemeters.

    Science.gov (United States)

    Santos, J P; Fernandes, A C; Gonçalves, I C; Marques, J G; Carvalho, A F; Santos, L; Cardoso, J; Osvay, M

    2006-01-01

    Al(2)O(3):Mg,Y thermoluminescence (TL) dosemeters were used to measure photon and fast neutron doses in a fast neutron beam recently implemented at the Portuguese Research Reactor, Nuclear and Technological Institute, Portugal. The activation of Al(2)O(3):Mg,Y by fast neutrons provides information about the fast neutron component by measuring the activity of the reaction products and the self-induced TL signal. Additionally, the first TL reading after irradiation determines the photon dose. The elemental composition of the dosemeters was determined by instrumental neutron activation analysis and by particle induced X-ray emission. Results demonstrate that Al(2)O(3):Mg,Y is an adequate material to discriminate photon and fast neutron fields for reactor dosimetry purposes.

  10. Review of optically stimulated luminescence (OSL) instrumental developments for retrospective dosimetry

    DEFF Research Database (Denmark)

    Bøtter-Jensen, Lars; Thomsen, Kristina Jørkov; Jain, Mayank

    2010-01-01

    This review describes 40 years of experience gained at Risø National Laboratory in the development of facilities for irradiation, thermal/optical stimulation and luminescence signal detection. These facilities have mainly been used in luminescence dating and nuclear accident dosimetry. We focus e...... especially on methods for light stimulation and irradiation, and developments of new portable TL/OSL readers for determining doses directly in the field on both Earth and the planet Mars....

  11. Consequences of air around an ionization chamber : Are existing solid phantoms suitable for reference dosimetry on an MR-linac?

    NARCIS (Netherlands)

    Hackett, S. L.; Van Asselen, B.; Wolthaus, J. W H; Kok, J. G M; Woodings, S. J.; Lagendijk, J. J W; Raaymakers, B. W.

    2016-01-01

    Purpose: A protocol for reference dosimetry for the MR-linac is under development. The 1.5 T magnetic field changes the mean path length of electrons in an air-filled ionization chamber but has little effect on the electron trajectories in a surrounding phantom. It is therefore necessary to correct

  12. Absolute and relative dosimetry for ELIMED

    Science.gov (United States)

    Cirrone, G. A. P.; Cuttone, G.; Candiano, G.; Carpinelli, M.; Leonora, E.; Lo Presti, D.; Musumarra, A.; Pisciotta, P.; Raffaele, L.; Randazzo, N.; Romano, F.; Schillaci, F.; Scuderi, V.; Tramontana, A.; Cirio, R.; Marchetto, F.; Sacchi, R.; Giordanengo, S.; Monaco, V.

    2013-07-01

    The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

  13. Trigeminal neuralgia treatment dosimetry of the Cyberknife

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Anthony [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Lo, Anthony T., E-mail: tonyho22003@yahoo.com [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Dieterich, Sonja; Soltys, Scott G.; Gibbs, Iris C. [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Chang, Steve G.; Adler, John R. [Department of Neurosurgery, Stanford University, Stanford, CA (United States)

    2012-04-01

    There are 2 Cyberknife units at Stanford University. The robot of 1 Cyberknife is positioned on the patient's right, whereas the second is on the patient's left. The present study examines whether there is any difference in dosimetry when we are treating patients with trigeminal neuralgia when the target is on the right side or the left side of the patient. In addition, we also study whether Monte Carlo dose calculation has any effect on the dosimetry. We concluded that the clinical and dosimetric outcomes of CyberKnife treatment for trigeminal neuralgia are independent of the robot position. Monte Carlo calculation algorithm may be useful in deriving the dose necessary for trigeminal neuralgia treatments.

  14. Absolute and relative dosimetry for ELIMED

    Energy Technology Data Exchange (ETDEWEB)

    Cirrone, G. A. P.; Schillaci, F.; Scuderi, V. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Institute of Physics Czech Academy of Science, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Carpinelli, M. [INFN Sezione di Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Leonora, E.; Randazzo, N. [INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy); Presti, D. Lo [INFN-Sezione di Catania, Via Santa Sofia 64, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Raffaele, L. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy); Tramontana, A. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Cirio, R.; Sacchi, R.; Monaco, V. [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino, Italy and Università di Torino, Dipartimento di Fisica, Via P.Giuria, 1 10125 Torino (Italy); Marchetto, F.; Giordanengo, S. [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino (Italy)

    2013-07-26

    The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

  15. Technical basis document for internal dosimetry

    CERN Document Server

    Hickman, D P

    1991-01-01

    This document provides the technical basis for the Chem-Nuclear Geotech (Geotech) internal dosimetry program. Geotech policy describes the intentions of the company in complying with radiation protection standards and the as low as reasonably achievable (ALARA) program. It uses this policy and applicable protection standards to derive acceptable methods and levels of bioassay to assure compliance. The models and computational methods used are described in detail within this document. FR-om these models, dose- conversion factors and derived limits are computed. These computations are then verified using existing documentation and verification information or by demonstration of the calculations used to obtain the dose-conversion factors and derived limits. Recommendations for methods of optimizing the internal dosimetry program to provide effective monitoring and dose assessment for workers are provided in the last section of this document. This document is intended to be used in establishing an accredited dosi...

  16. Thermocurrent dosimetry with high purity aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Fullerton, G.D.; Cameron, J.R.; Moran, P.R.

    1976-01-01

    The application of thermocurrent (TC) to ionizing radiation dosimetry was studied. It was shown that TC in alumina (Al/sub 2/O/sub 3/) has properties that are suited to personnel dosimetry and environmental monitoring. TC dosimeters were made from thin disks of alumina. Aluminum electrodes were evaporated on each side: on one face a high voltage electrode and on the opposite face a measuring electrode encircled by a guard ring. Exposure to ionizing radiation resulted in stored electrons and holes in metastable trapping sites. The signal was read-out by heating the dosimeter with a voltage source and picnometer connected in series between the opposite electrodes. The thermally remobilized charge caused a transient TC. The thermogram, TC versus time or temperature, is similar to a TL glow curve. Either the peak current or the integrated current is a measure of absorbed dose. Six grades of alumina were studied from a total of four commercial suppliers. All six materials displayed radiation induced TC signals. Sapphire of uv-grade quality from the Adolf Meller Co. (AM) had the best dosimetry properties of those investigated. Sources of interference were studied. Thermal fading, residual signal and radiation damage do not limit TC dosimetry. Ultraviolet light can induce a TC response but it is readily excluded with uv-opaque cladding. Improper surface preparation prior to electrode evaporation was shown to cause interference. A spurious TC signal resulted from polarization of surface contaminants. Spurious TC was reduced by improved cleaning prior to electrode application. Polished surfaces resulted in blocking electrodes and caused a sensitivity shift due to radiation induced thermally activated polarization. This was not observed with rough cut surfaces.

  17. Report: dosimetry of diagnostic exams in nuclear medicine; Rapport: dosimetrie des explorations diagnostiques en medecine nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Touzery, C. [Centre Regional de Lutte Contre le Cancer de Bourgogne, Centre Georges-Francois Leclerc, 21 - Dijon (France); Aubert, B. [Institut Gustave Roussy, 94 - Villejuif (France); Caselles, O. [Centre Claudius-Regaud, 31 - Toulouse (France); Gardin, I. [Centre Henri Becquerel, 76 - Rouen (France); Guilhem, M.Th. [Centre Hospitalier Regional de la Source, 45 - Orleans (France); Laffont, S. [Centre Eugene-Marquis, 35 - Rennes (France); Lisbona, A. [Centre Regional de Lutte Contre le Cancer Rene-Gauducheau, 44 - Nantes (France)

    2002-07-01

    A compilation about dosimetry of diagnosis explorations in nuclear medicine is presented in this issue. Dosimetry tables of the different radiopharmaceuticals used in nuclear medicine give indications on absorbed and efficient doses according the patients age from one year to adult age. The doses received by a fetus during a lung scintigraphy realized for the pregnant woman susceptible to suffer of pulmonary emboli is presented. A table of efficient doses for the infants until the age of six months for the principal scintigraphy explorations realized in nuclear medicine are given. A chapter of theoretical headlines is devoted to dosimetry and the calculations methods of absorbed and efficient doses in function of patients age. A short chapter concerns the recommendations to explore nursing mothers by scintigraphy. A last chapter treats the efficient doses received during explorations using ionizing radiations in radiology and their place in annual natural irradiation scale. (N.C.)

  18. Synthetic diamond devices for medical dosimetry applied to radiotherapy; Etude et developpement de dispositifs en diamant synthetique pour la dosimetrie medicale: applications en radiotherapie

    Energy Technology Data Exchange (ETDEWEB)

    Descamps, C

    2007-06-15

    The aim of this thesis, lead in the framework of an integrated European project entitled M.A.E.S.T.R.O. for ' Methods and Advanced Equipment for Simulation and Treatment in Radio Oncology', was to develop and test synthetic diamond detector in clinical environment for new modalities used in radiotherapy. Diamond is a good candidate for the detection of high energy beams in medical fields. It can be used for passive dosimetry, as thermoluminescent dosimeters or for active dosimetry as ionisation chambers. These two applications are presented here. Concerning the thermoluminescence, several impurities or dopants (boron, phosphorus, and nitrogen) have been incorporated in the diamond films during growth, in order to modify the material dosimetric properties and a detailed study of nitrogen-containing films is proposed. The second part presents the results obtained in active dosimetry. Two guide lines were followed: the measurement set-up optimisation and the material modification. The first dosimetric studies under radiotherapy beams concerning nitrogen-containing polycrystalline diamond as well as high purity single crystal diamond are conclusive. The detectors behaviours are in agreement with the recommendations of the International Atomic Energy Agency (IAEA). (author)

  19. Reconstructive dosimetry for cutaneous radiation syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Lima, C.M.A.; Lima, A.R.; Degenhardt, Ä.L.; Da Silva, F.C.A., E-mail: dasilva@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Valverde, N.J. [Fundacao Eletronuclear de Assistencia Medica, Rio de Janeiro, RJ (Brazil)

    2015-10-15

    According to the International Atomic Energy Agency (IAEA), a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS) in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry. (author)

  20. Hanford Internal Dosimetry Project manual. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Carbaugh, E.H.; Bihl, D.E.; MacLellan, J.A.; Long, M.P.

    1994-07-01

    This document describes the Hanford Internal Dosimetry Project, as it is administered by Pacific Northwest Laboratory (PNL) in support of the US Department of Energy and its Hanford contractors. Project services include administrating the bioassay monitoring program, evaluating and documenting assessment of potential intakes and internal dose, ensuring that analytical laboratories conform to requirements, selecting and applying appropriate models and procedures for evaluating radionuclide deposition and the resulting dose, and technically guiding and supporting Hanford contractors in matters regarding internal dosimetry. Specific chapters deal with the following subjects: practices of the project, including interpretation of applicable DOE Orders, regulations, and guidance into criteria for assessment, documentation, and reporting of doses; assessment of internal dose, including summary explanations of when and how assessments are performed; recording and reporting practices for internal dose; selection of workers for bioassay monitoring and establishment of type and frequency of bioassay measurements; capability and scheduling of bioassay monitoring services; recommended dosimetry response to potential internal exposure incidents; quality control and quality assurance provisions of the program.

  1. Electron paramagnetic resonance dosimetry using synthetic hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kwon; Kim, Hwi Young; Ye, Sung Joon [Seoul National University, Seoul (Korea, Republic of); Hirata, Hiroshi [Hokkaido University, Sapporo (Japan); Park, Jong Min [Seoul National University Hospital, Seoul (Korea, Republic of)

    2014-11-15

    The victims exposed doses under 3.5-4.0 Gy have chance to survive if treated urgently. To determine the priority of treatment among a large number of victims, the triage – distinguishing patients who need an urgent treatment from who may not be urgent – is necessary based on radiation biodosimetry. A current gold standard for radiation biodosimetry is the chromosomal assay using human lymphocytes. But this method requires too much time and skilled labors to cover the mass victims in radiation emergencies. Electron paramagnetic resonance (EPR) has been known for its capability of quantifying radicals in matters. EPR dosimetry is based on the measurement of stable radiation-induced radicals in tooth enamel. Hydroxyapatite (HAP) (Ca10(PO4)6(OH)2) contained in tooth enamel is a major probe for radiation dose reconstruction. This HAP dosimetry study was performed using a novel EPR spectrometer in Hokkaido University, Japan. The EPR dose-response curve was made using HAP samples. The blind test using 250 cGy samples showed the feasibility of EPR dosimetry for the triage purpose.

  2. Reconstructive dosimetry for cutaneous radiation syndrome.

    Science.gov (United States)

    Lima, C M A; Lima, A R; Degenhardt, Ä L; Valverde, N J; Silva, F C A da

    2015-10-01

    According to the International Atomic Energy Agency (IAEA), a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS) in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry.

  3. Reconstructive dosimetry for cutaneous radiation syndrome

    Directory of Open Access Journals (Sweden)

    C.M.A. Lima

    2015-01-01

    Full Text Available According to the International Atomic Energy Agency (IAEA, a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry.

  4. Software tool for portal dosimetry research.

    Science.gov (United States)

    Vial, P; Hunt, P; Greer, P B; Oliver, L; Baldock, C

    2008-09-01

    This paper describes a software tool developed for research into the use of an electronic portal imaging device (EPID) to verify dose for intensity modulated radiation therapy (IMRT) beams. A portal dose image prediction (PDIP) model that predicts the EPID response to IMRT beams has been implemented into a commercially available treatment planning system (TPS). The software tool described in this work was developed to modify the TPS PDIP model by incorporating correction factors into the predicted EPID image to account for the difference in EPID response to open beam radiation and multileaf collimator (MLC) transmitted radiation. The processes performed by the software tool include; i) read the MLC file and the PDIP from the TPS, ii) calculate the fraction of beam-on time that each point in the IMRT beam is shielded by MLC leaves, iii) interpolate correction factors from look-up tables, iv) create a corrected PDIP image from the product of the original PDIP and the correction factors and write the corrected image to file, v) display, analyse, and export various image datasets. The software tool was developed using the Microsoft Visual Studio.NET framework with the C# compiler. The operation of the software tool was validated. This software provided useful tools for EPID dosimetry research, and it is being utilised and further developed in ongoing EPID dosimetry and IMRT dosimetry projects.

  5. Diagnostic radiology dosimetry: status and trends

    Energy Technology Data Exchange (ETDEWEB)

    Rivera M, T., E-mail: trivera@ipn.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    Full text: Medical radiation is by far the largest man-made source of public exposure to ionizing radiation. Since 1970 the expression of protection standards shifted from a dose- to a risk-based approach, with dose limits established to yield risks to radiation workers comparable with those for workers in other safe industries. Another hand, worldwide interest in patient dose measurement was stimulated by the publication of Patient Dose Reduction in Diagnostic Radiology by the UK National Radiological Protection Board (NRPB). In response to heightened awareness of the importance of patient dose contributed by radiology procedures, there has been a general trend to effect control of patient doses by applying the principles of optimization coupled with an increase in regulatory enforcement. In this sense, thermoluminescent dosimetry (TLD) has been actively proposed in the last 3 decades thanks to their successful applications in diagnostic radiology. At the same time, it is emerged as the best radiation dosimetry method. The present work presents advantages of thermoluminescent dosimetry for X-ray beams measurements and its optimization. (Author)

  6. Methodological aspects of EPR dosimetry with teeth

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, S.; Chumak, V. [Scientific Center for Radiation Medicine, Kiev (Ukraine)

    2001-07-01

    EPR dosimetry with tooth enamel is known today as one of the most reliable and accurate methods of retrospective dosimetry. In the present study a comprehensive analysis of influence of the major confounding factors (solar UV exposure and dental X-ray diagnostic procedures) on the accuracy of accidental dose reconstruction is given. In this analysis, the facts known from literature as well as own authors' results were considered. Among the latter it is worth to mention study of doses in enamel caused by X-ray diagnostic procedures as well as investigation of dose profiles in front teeth, which are most affected to solar radiation. As a main result, the variant of dosimetric technique is proposed. It comprises the optimal combination of strongest sides of existing techniques which allows to conduct routine reconstruction of accidental doses as low as few tens of mGy with errors of the same order of magnitude. The proposed technique is primarily destined for dosimetry of Chernobyl liquidators, but could be used for reconstruction of doses of other over-exposed categories. (orig.)

  7. In vivo dosimetry in external beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mijnheer, Ben [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam 1066 CX (Netherlands); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Izewska, Joanna [Division of Human Health, International Atomic Energy Agency, Vienna 1400 (Austria); Reft, Chester [Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, Illinois 60637 (United States)

    2013-07-15

    In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

  8. Sensitivity studies associated with dosimetry experiment interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Bourganel, S.; Soldevila, M. [CEA/DANS/DM2S/SERMA, CEA Saclay, 91191, Gif sur Yvette (France); Ferrer, A.; Gregoire, G.; Destouches, C.; Beretz, D. [CEA/DEN-CAD/DER/SPEX, CEA Cadarache, F13108, Saint Paul lez Durance (France)

    2011-07-01

    Document available in abstract form only, full text of document follows: Interpretation of reactor dosimetry experiments with C/E comparison requires precise knowledge of parameters involved in modeling. Some parameters have more weight than others on the calculated values. So, sensitivity studies should be conducted to verify the importance of these parameters. The conclusions of these studies are used to refine the experiment modeling, or to correct uncertainty calculations. The results of these sensitivity studies allow a post-irradiation analysis, which can justify the discarding of some atypical C/M values. Derived uncertainties may be improved by the sensitivity analyses. Beyond classical parameters as geometry or composition, this paper describes some specific sensitivity studies conducted for dosimetry irradiation in reactor, and presents conclusions. These studies are based on dosimeters irradiated in the EOLE reactor facility at Cadarache CEA center. Conclusions drawn from these studies are generic and can be applied to any dosimetry study. Calculations performed for these studies were realized using TRIPOLI-4 Monte Carlo code. (authors)

  9. Patient dosimetry in classical radiology;Dosimetrie patient en radiologie classique

    Energy Technology Data Exchange (ETDEWEB)

    Valero, M. [Autorite de Surete Nucleaire, 75 Paris (France); Sirinelli, D. [Tours Univ., 37 (France); Chateil, J.F. [CHU Bordeaux, 33 (France)

    2009-10-15

    The objective is to give to the participants the means to determine, by simple methods, the dose delivered to skin during a radiological examination (conventional or numerical). The message to remember is: the use of a numerical detector does not lead systematically to reduce the dose at the patient. The dose.length product is a risk indicator. It is important to compare our practices to the procedures written in the guide of procedures and to note and to send to I.R.S.N. the dosimetry data relative to the dosimetry reference levels. (N.C.)

  10. Micrometer-resolved film dosimetry using a microscope in microbeam radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Bartzsch, Stefan, E-mail: stefan.bartzsch@icr.ac.uk; Oelfke, Uwe [The Institute of Cancer Research, 15 Cotswold Road, Sutton SM2 5NG (United Kingdom); Lott, Johanna; Welsch, Katrin [Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg (Germany); Bräuer-Krisch, Elke [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, Grenoble Cedex 9 38043 (France)

    2015-07-15

    Purpose: Microbeam radiation therapy (MRT) is a still preclinical tumor therapy approach that uses arrays of a few tens of micrometer wide parallel beams separated by a few 100 μm. The production, measurement, and planning of such radiation fields are a challenge up to now. Here, the authors investigate the feasibility of radiochromic film dosimetry in combination with a microscopic readout as a tool to validate peak and valley doses in MRT, which is an important requirement for a future clinical application of the therapy. Methods: Gafchromic{sup ®} HD-810 and HD-V2 films are exposed to MRT fields at the biomedical beamline ID17 of the European Synchrotron Radiation Facility (ESRF) and are afterward scanned with a microscope. The measured dose is compared with Monte Carlo calculations. Image analysis tools and film handling protocols are developed that allow accurate and reproducible dosimetry. The performance of HD-810 and HD-V2 films is compared and a detailed analysis of the resolution, noise, and energy dependence is carried out. Measurement uncertainties are identified and analyzed. Results: The dose was measured with a resolution of 5 × 1000 μm{sup 2} and an accuracy of 5% in the peak and between 10% and 15% in the valley region. As main causes for dosimetry uncertainties, statistical noise, film inhomogeneities, and calibration errors were identified. Calibration errors strongly increase at low doses and exceeded 3% for doses below 50 and 70 Gy for HD-V2 and HD-810 films, respectively. While the grain size of both film types is approximately 2 μm, the statistical noise in HD-V2 is much higher than in HD-810 films. However, HD-810 films show a higher energy dependence at low photon energies. Conclusions: Both film types are appropriate for dosimetry in MRT and the microscope is superior to the microdensitometer used before at the ESRF with respect to resolution and reproducibility. However, a very careful analysis of the image data is required

  11. SU-E-J-214: MR Protocol Development to Visualize Sirius MRI Markers in Prostate Brachytherapy Patients for MR-Based Post-Implant Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lim, T; Wang, J; Frank, S; Stafford, R; Bruno, T; Bathala, T; Mahmood, U; Pugh, T; Ibbott, G; Kudchadker, R [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: The current CT-based post-implant dosimetry allows precise seed localization but limited anatomical delineation. Switching to MR-based post-implant dosimetry is confounded by imprecise seed localization. One approach is to place positive-contrast markers (Sirius) adjacent to the negative-contrast seeds. This patient study aims to assess the utility of a 3D fast spoiled gradient-recalled echo (FSPGR) sequence to visualize Sirius markers for post-implant dosimetry. Methods: MRI images were acquired in prostate implant patients (n=10) on Day 0 (day-of-implant) and Day 30. The post-implant MR protocol consisted of 3D T2-weighted fast-spin-echo (FSE), T2-weighted 2D-FSE (axial) and T1-weighted 2D-FSE (axial/sagittal/coronal). We incorporated a 3D-FSPGR sequence into the post-implant MR protocol to visualize the Sirius markers. Patients were scanned with different number-of-excitations (6, 8, 10), field-of-view (10cm, 14cm, 18cm), slice thickness (1mm, 0.8mm), flip angle (14 degrees, 20 degrees), bandwidth (122.070 Hz/pixel, 325.508 Hz/pixel, 390.625 Hz/pixel), phase encoding steps (160, 192, 224, 256), frequency-encoding direction (right/left, anterior/posterior), echo-time type (minimum-full, out-of-phase), field strength (1.5T, 3T), contrast (with, without), scanner vendor (Siemens, GE), coil (endorectal-coil only, endorectal-and-torso-coil, torsocoil only), endorectal-coil filling (30cc, 50cc) and endorectal-coil filling type (air, perfluorocarbon [PFC]). For post-implant dosimetric evaluation with greater anatomical detail, 3D-FSE images were fused with 3D-FSPGR images. For comparison with CT-based post-implant dosimetry, CT images were fused with 3D-FSPGR images. Results: The 3D-FSPGR sequence facilitated visualization of markers in patients. Marker visualization helped distinguish signal voids as seeds versus needle tracks for more definitive MR-based post-implant dosimetry. On the CT-MR fused images, the distance between the seed on CT to MR images was 3

  12. Scintillation properties of the YVO{sub 4}:Eu{sup 3+} compound in powder form. Its application to dosimetry in radiation fields produced by pulsed mega-voltage photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Nahuel; Molina, Pablo; Santiago, Martin; Caselli, Eduardo [National University of Central Buenos Aires, Tandil (Argentina). Inst. de Fisica Arroyo Seco; Teichmann, Tobias; Sommer, Marian; Henniger, Juergen [Dresden University of Technology (Germany). Radiation Physics Group

    2015-07-01

    The investigation of scintillation properties of europium doped yttrium orthovanadate shows the suitability of this material for fiber-based dose rate measurements. All measurements were carried out with a 6 MV Varian linear accelerator. The temperature dependence of the signal is lower than that of the plastic scintillators reported so far. By measuring the afterglow of probes between Linac-pulses, the signal due to the stem effect can be successfully eliminated. Comparison of depth dose profiles in a water phantom for radiation field dimensions between 1 x 1 cm{sup 2} and 10 x 10 cm{sup 2} shows that the probes are suitable for small fields having dimensions up to 1 x 1 cm{sup 2}. The high light yield of probes having dimensions of 1 mm opens up the possibility for their use in spatially confined radiation fields, such as in intensity-modulated radiotherapy (IMRT) and volume-modulated radiation therapy (VMAT).

  13. Performance of Regolith Feed Systems for Analog Field Tests of In-Situ Resource Utilization Oxygen Production Plants in Mauna Kea, Hawaii

    Science.gov (United States)

    Townsend, Ivan I.; Mueller, Robert P.; Mantovani, James G.; Zacny, Kris A.; Craft, Jack

    2010-01-01

    This paper focuses on practical aspects of mechanical auger and pneumatic regolith conveying system feeding In-Situ Resource Utilization Oxygen production plants. The subsystems of these feedstock delivery systems include an enclosed auger device, pneumatic venturi educator, jet-lift regolith transfer, innovative electro-cyclone gas-particle separation/filtration systems, and compressors capable of dealing with hot hydrogen and/or methane gas re-circulating in the system. Lessons learned from terrestrial laboratory, reduced gravity and field testing on Mauna Kea Volcano in Hawaii during NASA lunar analog field tests will be discussed and practical design tips will be presented.

  14. Preliminary organic geochemical study of lignite from the Smederevsko Pomoravlje field (Kostolac basin, Serbia: Reconstruction of geological evolution and potential for rational utilization

    Directory of Open Access Journals (Sweden)

    Đoković Nataša

    2015-01-01

    Full Text Available The paper is aimed to determine the origin and geological evolution of lignites from Smederevsko Pomoravlje field (Kostolac Basin, Serbia. Possible rational utilization of coal is also considered. For this purpose numerous organic geochemical analyses have been applied to representative lignite samples. Obtained results showed that coal from the Smederevsko Pomoravlje field is typical humic coal. Peat-forming vegetation is dominated by gymnosperm plants. Coal forming plants belonged to the gymnosperm families Taxodiaceae, Cupressaceae, Phyllocladaceae and Pinaceae. Other precursors of organic matter (OM were microbial biomass, ferns and angiosperms. It is established that peatification was performed in neutral to slightly acidic, fresh water environment under anoxic to suboxic redox conditions. Maturity of OM is low in the phase of intense diagenetic processes. Biomarker compositions and values of corresponding parameters revealed that Smederevsko Pomoravlje field, Drmno field (Kostolac Basin and “A“ field (Kovin deposit represent a part of the unique lignite basin. Results of this study suggest possible rational utilization of the Smederevsko Pomoravlje lignites in thermal power plants. This is particularly related to samples from coal seam I. Significant amount of gas could be generated from lignites at higher maturities. Eight samples meet basic assumptions for effective gasification. [Projekat Ministarstva nauke Republike Srbije, br. 176006

  15. Utilizing an Artificial Outcrop to Scaffold Learning between Laboratory and Field Experiences in a College-Level Introductory Geology Course

    Science.gov (United States)

    Wilson, Meredith

    2012-01-01

    Geologic field trips are among the most beneficial learning experiences for students as they engage the topic of geology, but they are also difficult environments to maximize learning. This action research study explored one facet of the problems associated with teaching geology in the field by attempting to improve the transition of undergraduate…

  16. Utilizing an Artificial Outcrop to Scaffold Learning between Laboratory and Field Experiences in a College-Level Introductory Geology Course

    Science.gov (United States)

    Wilson, Meredith

    2012-01-01

    Geologic field trips are among the most beneficial learning experiences for students as they engage the topic of geology, but they are also difficult environments to maximize learning. This action research study explored one facet of the problems associated with teaching geology in the field by attempting to improve the transition of undergraduate…

  17. Reference dosimetry of proton pencil beams based on dose-area product: a proof of concept

    Science.gov (United States)

    Gomà, Carles; Safai, Sairos; Vörös, Sándor

    2017-06-01

    This paper describes a novel approach to the reference dosimetry of proton pencil beams based on dose-area product (DAPw ). It depicts the calibration of a large-diameter plane-parallel ionization chamber in terms of dose-area product in a 60Co beam, the Monte Carlo calculation of beam quality correction factors—in terms of dose-area product—in proton beams, the Monte Carlo calculation of nuclear halo correction factors, and the experimental determination of DAPw of a single proton pencil beam. This new approach to reference dosimetry proves to be feasible, as it yields DAPw values in agreement with the standard and well-established approach of determining the absorbed dose to water at the centre of a broad homogeneous field generated by the superposition of regularly-spaced proton pencil beams.

  18. Use of a liquid ionization chamber for stereotactic radiotherapy dosimetry.

    Science.gov (United States)

    Wagner, A; Crop, F; Lacornerie, T; Vandevelde, F; Reynaert, N

    2013-04-21

    Liquid ionization chambers (LICs) offer an interesting tool in the field of small beam dosimetry, allowing better spatial resolution and reduced perturbation effects. However, some aspects remain to be addressed, such as the higher recombination and the effects from the materials of the detector. Our aim was to investigate these issues and their impact. The first step was the evaluation of the recombination effects. Measurements were performed at different SSDs to vary the dose per pulse, and the collection efficiency was obtained. The BEAMnrc code was then used to model the Cyberknife head. Finally, the liquid ionization chamber itself was modelled using the EGSnrc-based code Cavity allowing the evaluation of the influence of the volume and the chamber materials. The liquid ionization charge collection efficiency is approximately 0.98 at 1.5 mGy pulse(-1), the highest dose per pulse that we have measured. Its impact on the accuracy of output factors is less than half a per cent. The detector modelling showed a significant contribution from the graphite electrode, up to 6% for the 5 mm collimator. The dependence of the average electronic mass collision stopping power of iso-octane with beam collimation is negligible and thus has no influence on output factor measurements. Finally, the volume effect reaches 5% for the small 5 mm collimator and becomes much smaller (<0.5%) for diameters above 10 mm. LICs can effectively be used for small beam relative dosimetry as long as adequate correction factors are applied, especially for the electrode and volume effects.

  19. New developed cylindrical TM010 mode EPR cavity for X-band in vivo tooth dosimetry.

    Directory of Open Access Journals (Sweden)

    Guo Junwang

    Full Text Available EPR tooth in vivo dosimetry is an attractive approach for initial triage after unexpected nuclear events. An X-band cylindrical TM010 mode resonant cavity was developed for in vivo tooth dosimetry and used in EPR applications for the first time. The cavity had a trapezoidal measuring aperture at the exact position of the cavity's cylindrical wall where strong microwave magnetic field H1 concentrated and weak microwave electric field E1 distributed. Theoretical calculations and simulations were used to design and optimize the cavity parameters. The cavity features were evaluated by measuring DPPH sample, intact incisor samples embed in a gum model and the rhesus monkey teeth. The results showed that the cavity worked at designed frequency and had the ability to make EPR spectroscopy in relative high sensitivity. Sufficient modulation amplitude and microwave power could be applied into the aperture. Radiation induced EPR signal could be observed remarkably from 1 Gy irradiated intact incisor within only 30 seconds, which was among the best in scan time and detection limit. The in vivo spectroscopy was also realized by acquiring the radiation induced EPR signal from teeth of rhesus monkey whose teeth was irradiated by dose of 2 Gy. The results suggested that the cavity was sensitive to meet the demand to assess doses of significant level in short time. This cavity provided a very potential option for the development of X-band in vivo dosimetry.

  20. 1983 international intercomparison of nuclear accident dosimetry systems at Oak Ridge National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Swaja, R.E.; Greene, R.T.; Sims, C.S.

    1985-04-01

    An international intercomparison of nuclear accident dosimetry systems was conducted during September 12-16, 1983, at Oak Ridge National Laboratory (ORNL) using the Health Physics Research Reactor operated in the pulse mode to simulate criticality accidents. This study marked the twentieth in a series of annual accident dosimetry intercomparisons conducted at ORNL. Participants from ten organizations attended this intercomparison and measured neutron and gamma doses at area monitoring stations and on phantoms for three different shield conditions. Results of this study indicate that foil activation techniques are the most popular and accurate method of determining accident-level neutron doses at area monitoring stations. For personnel monitoring, foil activation, blood sodium activation, and thermoluminescent (TL) methods are all capable of providing accurate dose estimates in a variety of radiation fields. All participants in this study used TLD's to determine gamma doses with very good results on the average. Chemical dosemeters were also shown to be capable of yielding accurate estimates of total neutron plus gamma doses in a variety of radiation fields. While 83% of all neutron measurements satisfied regulatory standards relative to reference values, only 39% of all gamma results satisfied corresponding guidelines for gamma measurements. These results indicate that continued improvement in accident dosimetry evaluation and measurement techniques is needed.

  1. Evaluation and development of X-ray detectors for dosimetry; Evaluierung und Entwicklung von Roentgendetektoren fuer die Dosimetrie

    Energy Technology Data Exchange (ETDEWEB)

    Boehnel, Michael

    2012-03-28

    thus be improved between 5% and 50% in the investigated photon energy interval of 9 keV to 60 keV. The energy resolution of the Timepix ASIC in the spectroscopic time-over-threshold mode is studied in detail with the help of the test pulse functionality, and the influence of different detector configurations is presented. The detector counting artifacts in the energy deposition spectra, arising in the time-over-threshold mode, are described using examples. A concluding discussion supplies a comparison of the energy resolving characteristics of the two operating modes of the Timepix detector. The results of the experiments concerning the characterisation of the Timepix detector are used for the extension of an existing Monte Carlo simulation. The modelling of the counting mode and the new implementation of the time-over-threshold mode in the simulation are presented. The main focus is the correct description of the energy deposition spectra in the simulation. A comparison of measurements and simulation results show a good agreement for the selected approach to modelling the Timepix detector. One application for the presented X-ray detectors is dosimetry. In this work a procedure is presented for determining the personal dose equivalent from the data of energy resolving pixelated X-ray detectors. The quality of the dose reconstruction obtained by simulations and experiments are demonstrated by utilizing a Timepix detector. For a field use in a dosemeter, the Timepix detector is not suitable due to its limitations. The need for the development of a new detector arises, a detector particularly adapted to the requirements of personal dosimetry. The outline of the development of the Dosepix detector is given and its functional principles are explained. The dosemeter for the determination of the personal dose equivalent H{sub p}(10) consists of three individual Dosepix detectors, with two of the units covered by converter materials (tin and aluminum). Based on simulations

  2. Dosimetry intercomparisons in European medical device sterilization plants

    DEFF Research Database (Denmark)

    Miller, A.; Sharpe, P.H.G.

    2000-01-01

    Dosimetry intercomparisons have been carried out involving two-thirds of all European radiation sterilization facilities. Dosimeters for the intercomparisons were supplied by two accredited calibration laboratories. The results show good agreement, and indicate overall dosimetry accuracy of the o...... of the order of +/-5% (1 sigma) for both Co-60 and electron beam plants. (C) 2000 Elsevier Science Ltd. All rights reserved....

  3. Neutron dosimetry and radiation damage calculations for HFBR

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Ratner, R.T. [Pacific Northwest National Lab., TN (United States)

    1998-03-01

    Neutron dosimetry measurements have been conducted for various positions of the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) in order to measure the neutron flux and energy spectra. Neutron dosimetry results and radiation damage calculations are presented for positions V10, V14, and V15.

  4. Use of the GATE Monte Carlo package for dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Visvikis, D. [INSERM U650, LaTIM, University Hospital Medical School, F 29609 Brest (France)]. E-mail: Visvikis.Dimitris@univ-brest.fr; Bardies, M. [INSERM U601, CHU Nantes, F 44093 Nantes (France); Chiavassa, S. [INSERM U601, CHU Nantes, F 44093 Nantes (France); Danford, C. [Department of Medical Physics, MSKCC, New York (United States); Kirov, A. [Department of Medical Physics, MSKCC, New York (United States); Lamare, F. [INSERM U650, LaTIM, University Hospital Medical School, F 29609 Brest (France); Maigne, L. [Departement de Curietherapie-Radiotherapie, Centre Jean Perrin, F 63000 Clemont-Ferrand (France); Staelens, S. [UGent-ELIS, St-Pietersnieuwstraat, 41, B 9000 Gent (Belgium); Taschereau, R. [CRUMP Institute for Molecular Imaging, UCLA, Los Angeles (United States)

    2006-12-20

    One of the roles for Monte Carlo (MC) simulation studies is in the area of dosimetry. A number of different codes dedicated to dosimetry applications are available and widely used today, such as MCNP, EGSnrc and PTRAN. However, such codes do not easily facilitate the description of complicated 3D sources or emission tomography systems and associated data flow, which may be useful in different dosimetry application domains. Such problems can be overcome by the use of specific MC codes such as GATE (GEANT4 Application to Tomographic Emission), which is based on Geant4 libraries, providing a scripting interface with a number of advantages for the simulation of SPECT and PET systems. Despite this potential, its major disadvantage is in terms of efficiency involving long execution times for applications such as dosimetry. The strong points and disadvantages of GATE in comparison to other dosimetry specific codes are discussed and illustrated in terms of accuracy, efficiency and flexibility. A number of features, such as the use of voxelised and moving sources, as well as developments such as advanced visualization tools and the development of dose estimation maps allowing GATE to be used for dosimetry applications are presented. In addition, different examples from dosimetry applications with GATE are given. Finally, future directions with respect to the use of GATE for dosimetry applications are outlined.

  5. Sandia National Laboratories Internal Dosimetry Technical Basis Manual (Rev 4)

    Energy Technology Data Exchange (ETDEWEB)

    Goke, Sarah Hayes [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Elliott, Nathan Ryan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    The Sandia National Laboratories’ Internal Dosimetry Technical Basis Manual is intended to provide extended technical discussion and justification of the internal dosimetry program at SNL. It serves to record the approach to evaluating internal doses from radiobioassay data, and where appropriate, from workplace monitoring data per the Department of Energy Internal Dosimetry Program Guide DOE G 441.1C. The discussion contained herein is directed primarily to current and future SNL internal dosimetrists. In an effort to conserve space in the TBM and avoid duplication, it contains numerous references providing an entry point into the internal dosimetry literature relevant to this program. The TBM is not intended to act as a policy or procedure statement, but will supplement the information normally found in procedures or policy documents. The internal dosimetry program outlined in this manual is intended to meet the requirements of Federal Rule 10CFR835 for monitoring the workplace and for assessing internal radiation doses to workers.

  6. Effects of Operating Pressure on Energy-saving of Water Recycling Utilization with MVR system in Oil Extraction Fields

    OpenAIRE

    Li, Liansheng; Zhao, Yuanyang; Wang, Le; Xiao, Jun; Yang, Qichao; Liu, Guangbin; Tang, Bin

    2015-01-01

    One of the most effective methods for the extraction of crude oil with high viscosity is injecting high temperature water vapor to the oil well. To save water consumption and achieve zero discharge, it is needed to separate and purify the water, which is mixed with oil, mud and other impurities. In this paper, the mechanical vapor recompression (MVR) system is analyzed and the parameters for analysis are based on a demonstration project on water recycling utilization in the Karamay crude oil ...

  7. Portal dosimetry for VMAT using integrated images obtained during treatment.

    Science.gov (United States)

    Bedford, James L; Hanson, Ian M; Hansen, Vibeke Nordmark

    2014-02-01

    Portal dosimetry provides an accurate and convenient means of verifying dose delivered to the patient. A simple method for carrying out portal dosimetry for volumetric modulated arc therapy (VMAT) is described, together with phantom measurements demonstrating the validity of the approach. Portal images were predicted by projecting dose in the isocentric plane through to the portal image plane, with exponential attenuation and convolution with a double-Gaussian scatter function. Appropriate parameters for the projection were selected by fitting the calculation model to portal images measured on an iViewGT portal imager (Elekta AB, Stockholm, Sweden) for a variety of phantom thicknesses and field sizes. This model was then used to predict the portal image resulting from each control point of a VMAT arc. Finally, all these control point images were summed to predict the overall integrated portal image for the whole arc. The calculated and measured integrated portal images were compared for three lung and three esophagus plans delivered to a thorax phantom, and three prostate plans delivered to a homogeneous phantom, using a gamma index for 3% and 3 mm. A 0.6 cm(3) ionization chamber was used to verify the planned isocentric dose. The sensitivity of this method to errors in monitor units, field shaping, gantry angle, and phantom position was also evaluated by means of computer simulations. The calculation model for portal dose prediction was able to accurately compute the portal images due to simple square fields delivered to solid water phantoms. The integrated images of VMAT treatments delivered to phantoms were also correctly predicted by the method. The proportion of the images with a gamma index of less than unity was 93.7% ± 3.0% (1SD) and the difference between isocenter dose calculated by the planning system and measured by the ionization chamber was 0.8% ± 1.0%. The method was highly sensitive to errors in monitor units and field shape, but less sensitive to

  8. Small Field Dosimetry Using Optical-Fiber Radioluminescence and Radpos Dosimetry Systems

    DEFF Research Database (Denmark)

    Ploquin, N.; Kertzscher Schwencke, Gustavo Adolfo Vladimir; Vandervoort, E.

    2012-01-01

    Inc, USA). The RL signal generated in the crystal by ionizing radiation can be read remotely via thin optical fiber cables. The system was originally developed for in vivo dose verification during external beam radiotherapy and brachytherapy (Radiother Oncol, 100 (3), 45662, 2011). However, due....... Detector readings for each cone were normalized to those for 60 mm cone. For MOSFET detectors in both mobileMOSFET and RADPOS systems, the corrections proposed by Francescon et al. (J Appl Clin Med Phys, 10 (1), 14752, 2009) were applied. Since FWHM of our Cyberknife source is 2.4mm, the μ...

  9. Dosimetry applications in GATE Monte Carlo toolkit.

    Science.gov (United States)

    Papadimitroulas, Panagiotis

    2017-02-21

    Monte Carlo (MC) simulations are a well-established method for studying physical processes in medical physics. The purpose of this review is to present GATE dosimetry applications on diagnostic and therapeutic simulated protocols. There is a significant need for accurate quantification of the absorbed dose in several specific applications such as preclinical and pediatric studies. GATE is an open-source MC toolkit for simulating imaging, radiotherapy (RT) and dosimetry applications in a user-friendly environment, which is well validated and widely accepted by the scientific community. In RT applications, during treatment planning, it is essential to accurately assess the deposited energy and the absorbed dose per tissue/organ of interest, as well as the local statistical uncertainty. Several types of realistic dosimetric applications are described including: molecular imaging, radio-immunotherapy, radiotherapy and brachytherapy. GATE has been efficiently used in several applications, such as Dose Point Kernels, S-values, Brachytherapy parameters, and has been compared against various MC codes which are considered as standard tools for decades. Furthermore, the presented studies show reliable modeling of particle beams when comparing experimental with simulated data. Examples of different dosimetric protocols are reported for individualized dosimetry and simulations combining imaging and therapy dose monitoring, with the use of modern computational phantoms. Personalization of medical protocols can be achieved by combining GATE MC simulations with anthropomorphic computational models and clinical anatomical data. This is a review study, covering several dosimetric applications of GATE, and the different tools used for modeling realistic clinical acquisitions with accurate dose assessment. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  10. Retrospective accident dosimetry using trapped charges

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. I.; Kim, J. L.; Chang, I.; Kim, B. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Dicentric chromosome aberrations technique scoring of aberrations in metaphases prepared from human lymphocytes is most commonly used. This is considered as a reliable technique because the sample is extracted from the individual human body itself. There are other techniques in biological dosimetry such as Fluorescence In Situ Hybridization (FISH) using translocations, premature chromosome condensation (PCC) and micronucleus assay. However the minimum detectable doses (MDD) are relatively high and sample preparation time is also relatively longer. Therefore, there is limitation in use of these techniques for the purpose of triage in a short time in case of emergency situation relating large number of persons. Electronic paramagnetic resonance (EPR) technique is based on the signal from unpaired electrons such as free radicals in irradiated materials especially tooth enamel, however it has also limitation for the purpose of triage because of difficulty of sample taking and its high MDD. Recently as physical methods, thermoluminescence (TL) and optically stimulated luminescence (OSL) technique have been attracted due to its lower MDD and simplicity of sample preparation. Density of the trapped charges is generally proportional to the radiation dose absorbed and the intensity of emitting light is also proportional to the density of trapped charges, thus it can be applied to measure radiation dose retrospectively. In this presentation, TL and OSL techniques are going to introduced and discussed as physical methods for retrospective accident dosimetry using trapped charges especially in electronic component materials. As a tool for dose reconstruction for emergency situation, thermoluminescece and optically stimulated luminescence techniques which are based on trapped charges during exposure of material are introduced. These techniques have several advantages such as high sensitivity, fast evaluation and ease to sample collection over common biological dosimetry and EPR

  11. In vivo light dosimetry for pleural PDT

    Science.gov (United States)

    Dimofte, Andreea; Zhu, Timothy C.; Finlay, Jarod C.; Culligan, Melissa; Edmonds, Christine E.; Friedberg, Joseph S.; Cengel, Keith; Hahn, Stephen M.

    2009-02-01

    In-vivo light Dosimetry for patients undergoing photodynamic therapy (PDT) is one of the important dosimetry quantities critical for predicting PDT outcome. This study examines the light fluence (rate) delivered to patients undergoing pleural PDT as a function of treatment time, treatment volume and surface area, and its accuracy as a function of the calibration accuracies of each isotropic detector and the calibration integrating sphere. The patients studied here were enrolled in Phase II clinical trial of Photofrin-mediated PDT for the treatment of non-small cell lung cancer with pleural effusion. The ages of the patients studied varied from 34 to 69 year old. All patients were administered 2mg per kg body weight Photoprin 24 hours before the surgery. Patients undergoing photodynamic therapy (PDT) are treated with laser light with a light fluence of 60 J/cm^2 at 630nm. Fluence rate (mW/cm^2) and cumulative fluence (J/cm^2) was monitored at 7 different sites during the entire light treatment delivery. Isotropic detectors were used for in-vivo light dosimetry. The anisotropy of each isotropic detector was found to be within 30%. The mean fluence rate delivery varied from 37.84 to 94.05 mW/cm^2 and treatment time varied from 1762 to 5232s. We have established a correlation between the treatment time and the treatment volume. The results are discussed using an integrating sphere theory and the measured tissue optical properties. The result can be used as a clinical guideline for future pleural PDT treatment.

  12. [Lithium fluoride: not only dosimetry, but also X ray imaging?].

    Science.gov (United States)

    Bonfigli, F; Campurra, G; Montereali, R M; Vincenti, M A

    2011-01-01

    Lithium fluoride is a well known material used for dosimetry. In the last years it was proposed and tested also as imaging detector for X-ray microscopy. Optical microscopy represents the oldest and most used imaging technique for medicine and cell biology investigations; later other imaging techniques, including electron microscopy, were introduced. The recent technological developments in the soft X-ray field, concerning sources, optics and detectors, have been increased the interest of physicians and biologists for X-ray microscopy, mainly to obtain in vivo imaging of cells. An innovative imaging detector has been proposed and tested by researchers of C.R. ENEA Frascati, as handy, versatile and compact plate for soft X-ray imaging with very high spatial resolution, wide dynamic range, large field of view and easy to read by an optical microscope. Scientific and technological applications can be foreseen in several fields, as nanotechnologies, materials, photonics, life science and microscopy (including cell imaging, also in vivo).

  13. Application of advanced Monte Carlo Methods in numerical dosimetry.

    Science.gov (United States)

    Reichelt, U; Henniger, J; Lange, C

    2006-01-01

    Many tasks in different sectors of dosimetry are very complex and highly sensitive to changes in the radiation field. Often, only the simulation of radiation transport is capable of describing the radiation field completely. Down to sub-cellular dimensions the energy deposition by cascades of secondary electrons is the main pathway for damage induction in matter. A large number of interactions take place until such electrons are slowed down to thermal energies. Also for some problems of photon transport a large number of photon histories need to be processed. Thus the efficient non-analogue Monte Carlo program, AMOS, has been developed for photon and electron transport. Various applications and benchmarks are presented showing its ability. For radiotherapy purposes the radiation field of a brachytherapy source is calculated according to the American Association of Physicists in Medicine Task Group Report 43 (AAPM/TG43). As additional examples, results for the detector efficiency of a high-purity germanium (HPGe) detector and a dose estimation for an X-ray shielding for radiation protection are shown.

  14. Preclinical dosimetry of magnetic fluid hyperthermia for bladder cancer

    Science.gov (United States)

    Oliveira, Tiago R.; Stauffer, Paul R.; Lee, Chen-Ting; Landon, Chelsea; Etienne, Wiguins; Maccarini, Paolo F.; Inman, Brant; Dewhirst, Mark W.

    2013-02-01

    Background Despite positive efficacy, thermotherapy is not widely used in clinical oncology. Difficulties associated with field penetration and controlling power deposition patterns in heterogeneous tissue have limited its use for heating deep in the body. Heat generation using iron-oxide super-paramagnetic nanoparticles excited with magnetic fields has been demonstrated to overcome some of these limitations. The objective of this preclinical study is to investigate the feasibility of treating bladder cancer with magnetic fluid hyperthermia (MFH) by analyzing the thermal dosimetry of nanoparticle heating in a rat bladder model. Methods The bladders of 25 female rats were injected with 0.4 ml of Actium Biosystems magnetite-based nanoparticles (Actium Biosystems, Boulder CO) via catheters inserted in the urethra. To assess the distribution of nanoparticles in the rat after injection we used the 7 T small animal MRI system (Bruker ClinScan, Bruker BioSpin MRI GmbH, Ettlingen, Germany). Heat treatments were performed with a small animal magnetic field applicator (Actium Biosystems, Boulder CO) with a goal of raising bladder temperature to 42°C in 1°C/min to a steady-state of 42°C. Conclusion Our data demonstrate that a MFH system provides well-localized heating of rat bladder with effective control of temperature in the bladder and minimal heating of surrounding tissues.

  15. Final Design for an International Intercomparison Exercise for Nuclear Accident Dosimetry at the DAF Using Godiva-IV: IER-148 CED-2 Report

    Energy Technology Data Exchange (ETDEWEB)

    Heinrichs, Dave [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beller, Tim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burch, Jennifer [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cummings, Rick [National Security Technologies, LLC. (NSTec), Mercury, NV (United States) Nevada National Security Site; Duluc, Matthieu [Inst. de Radioprotection et de Sûrete Nucleaire (ISRN), Fontenay-aux-Roses (France); Gadd, Milan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Goda, Joetta [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hickman, David [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McAvoy, Doug [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rathbone, Bruce [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sullivan, Randy [Savannah River Site (SRS), Aiken, SC (United States); Trompier, Francois [Inst. de Radioprotection et de Sûrete Nucleaire (ISRN), Fontenay-aux-Roses (France); Veinot, Ken [Y-12 National Security Complex, Oak Ridge, TN (United States); Ward, Dann [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Will, Rashelle [National Security Technologies, LLC. (NSTec), Mercury, NV (United States) Nevada National Security Site; Wilson, Chris [Atomic Weapons Establishment (AWE), Berkshire (United Kingdom); Zieziulewicz, Thomas [Knolls Atomic Power Lab. (KAPL), Niskayuna, NY (United States)

    2014-09-30

    This document is the Final Design (CED-2) Report for IER-148, “International Inter-comparison Exercise for Nuclear Accident Dosimetry at the DAF Using Godiva-IV.” The report describes the structure of the exercise consisting of three irradiations; identifies the participating laboratories and their points of contact; provides the details of all dosimetry elements and their placement in proximity to Godiva-IV on support stands or phantoms ; and lists the counting and spectroscopy equipment each laboratory will utilize in the Mercury NAD Lab. The exercise is tentatively scheduled for one week in August 2015.

  16. Secondary standard dosimetry laboratory at INFLPR

    Energy Technology Data Exchange (ETDEWEB)

    Scarlat, F.; Minea, R.; Scarisoreanu, A.; Badita, E.; Sima, E.; Dumitrascu, M.; Stancu, E.; Vancea, C., E-mail: scarlat.f@gmail.com [National Institute for Laser, Plasma and Radiation Physics - INFLPR, Bucharest (Romania)

    2011-07-01

    National Institute for Laser, Plasma and Radiation Physics (INFLPR) has constructed a High Energy Secondary Standard Dosimetry Laboratory SSDL-STARDOOR - for performing dosimetric calibrations according to ISO IEC SR/EN 17025:2005 standards. This is outfitted with UNIDOS Secondary Standard Dosimeter from PTW (Freiburg Physikalisch-Technische Werksttaten) calibrated at the PTB-Braunschweig (German Federal Institute of Physics and Metrology). A radiation beam of the quality of Q used by our laboratory as calibration source are provided by INFLPR 7 MeV electron beam linear accelerator mounted in our facility. (author)

  17. Characterization of brazilian wollastonite for radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Souza, D.N. [Departamento de Fisica, Universidade Federal de Sergipe, Sao Cristovao/SE (Brazil); Melo, A.P.; Gazano, V.S.O.; Caldas, L.V.E. [Instituto de Pesquisas Energeticas e Nucleares, Comissao Nacional de Energia Nuclear, Sao Paulo (Brazil)]. e-mail: dnsouza@fisca.ufs.br

    2006-07-01

    In these work preliminary results of the characterization analyses of Brazilian Wollastonite for radiation dosimetry are presented. Wollastonite is a silicate of calcium, Ca(SiO{sub 3}), and it was acquired in the form of rude mineral with Andradite inclusions. The sample was cleaned and prepared for obtained selected grains of Wollastonite. The analyses of chemical and mineralogical compositions were obtained using the neutron activation and X-ray powder diffraction techniques. The thermoluminescent (TL) glow curve of the material shows a prominent peak at about 200 C. TL emission spectra, and photoinduced emission spectra were also obtained. (Author)

  18. Enhanced field emission from ZnO nanowire arrays utilizing MgO buffer between seed layer and silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Si [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Chen, Jiangtao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Mid. Road, Lanzhou 730000 (China); Liu, Jianlin [Quantum Structures Laboratory, Department of Electrical and Computer Engineering, University of California, Riverside, CA 92521 (United States); Qi, Jing, E-mail: qijing@lzu.edu.cn [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, Yuhua, E-mail: wyh@lzu.edu.cn [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2016-11-30

    Highlights: • We obtained ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer. • FE properties of ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer is better than that without MgO buffer. • With MgO buffer, the ZnO seed layer shows lower top-bottom resistance and better electron transport. • The enhanced field emission properties can be attributed to good electron transport in seed layer, good nanowire alignment because of MgO buffer. - Abstract: Field emitters based on ZnO nanowires and other nanomaterials are promising high-brightness electron sources for field emission display, microscopy and other applications. The performance of a ZnO nanowire field emitter is linked to the quality, conductivity and alignment of the nanowires on a substrate, therefore requiring ways to improve these parameters. Here, ZnO nanowire arrays were grown on ZnO seed layer on silicon substrate with MgO buffer between the seed layer and Si. The turn-on field and enhancement factor of these nanowire arrays are 3.79 V/μm and 3754, respectively. These properties are improved greatly compared to those of ZnO nanowire arrays grown on ZnO seed layer without MgO buffer, which are 5.06 V/μm and 1697, respectively. The enhanced field emission properties can be attributed to better electron transport in seed layer, and better nanowire alignment because of MgO buffer.

  19. Energy and Exergy Analysis of Kalina Cycle for the Utilization of Waste Heat in Brine Water for Indonesian Geothermal Field

    Directory of Open Access Journals (Sweden)

    Nasruddin Nasruddin

    2015-04-01

    Full Text Available The utilization of waste heat in a power plant system—which would otherwise be released back to the environment—in order to produce additional power increases the efficiency of the system itself. The purpose of this study is to present an energy and exergy analysis of Kalina Cycle System (KCS 11, which is proposed to be utilized to generate additional electric power from the waste heat contained in geothermal brine water available in the Lahendong Geothermal power plant site in North Sulawesi, Indonesia. A modeling application on energy and exergy system is used to study the design of thermal system which uses KCS 11. To obtain the maximum power output and maximum efficiency, the system is optimized based on the mass fraction of working fluid (ammonia-water, as well as based on the turbine exhaust pressure. The result of the simulation is the optimum theoretical performance of KCS 11, which has the highest possible power output and efficiency. The energy flow diagram and exergy diagram (Grassman diagram was also presented for KCS 11 optimum system to give quantitative information regarding energy flow from the heat source to system components and the proportion of the exergy input dissipated in the various system components.

  20. Air core detectors for Cerenkov-free scintillation dosimetry of brachytherapy β-sources.

    Science.gov (United States)

    Eichmann, Marion; Thomann, Benedikt

    2017-09-01

    Plastic scintillation detectors are used for dosimetry in small radiation fields with high dose gradients, e.g., provided by β-emitting sources like (106) Ru/(106) Rh eye plaques. A drawback is a background signal caused by Cerenkov radiation generated by electrons passing the optical fibers (light guides) of this dosimetry system. Common approaches to correct for the Cerenkov signal are influenced by uncertainties resulting from detector positioning and calibration procedures. A different approach to avoid any correction procedure is to suppress the Cerenkov signal by replacing the solid core optical fiber with an air core light guide, previously shown for external beam therapy. In this study, the air core concept is modified and applied to the requirements of dosimetry in brachytherapy, proving its usability for measuring water energy doses in small radiation fields. Three air core detectors with different air core lengths are constructed and their performance in dosimetry for brachytherapy β-sources is compared with a standard two-fiber system, which uses a second fiber for Cerenkov correction. The detector systems are calibrated with a (90) Sr/(90) Y secondary standard and tested for their angular dependence as well as their performance in depth dose measurements of (106) Ru/(106) Rh sources. The signal loss relative to the standard detector increases with increasing air core length to a maximum value of 58.3%. At the same time, however, the percentage amount of Cerenkov light in the total signal is reduced from at least 12.1% to a value below 1.1%. There is a linear correlation between induced dose and measured signal current. The air core detectors determine the dose rates for (106) Ru/(106) Rh sources without any form of correction for the Cerenkov signal. The air core detectors show advantages over the standard two-fiber system especially when measuring in radiation fields with high dose gradients. They can be used as simple one-fiber systems and allow

  1. The Validity and Utility of the California Family Risk Assessment under Practice Conditions in the Field: A Prospective Study

    Science.gov (United States)

    Johnson, Will L.

    2011-01-01

    Objective: Analysis of the validity and implementation of a child maltreatment actuarial risk assessment model, the California Family Risk Assessment (CFRA). Questions addressed: (1) Is there evidence of the validity of the CFRA under field operating conditions? (2) Do actuarial risk assessment results influence child welfare workers' service…

  2. Silicon based light emitters utilizing radiation from dislocations; electric field induced shift of the dislocation-related luminescence

    NARCIS (Netherlands)

    Arguirov, T.; Mchedlidze, T.; Kittler, M.; Reiche, M.; Wilhelm, T.; Hoang, T.; Holleman, J.; Schmitz, J.

    2009-01-01

    Dislocation rich regions can be controllably formed at a certain location inside a silicon wafer. We studied the light emission properties of such regions located in an electric field of a p–n junction under different excitation conditions. It was found that the luminescence spectra of the dislocati

  3. Field Tests of “In-Situ” Remediation of Groundwater From Dissolved Mercury Utilizing Sulfate Reducing Bacteria

    Science.gov (United States)

    Field tests of biologically active filters have been conducted at groundwater mercury pollution site in Pavlodar, Kazakhstan. The biofilters represented cultures of sulfate-reducing bacteria (SRB) immobilized on claydite imbedded in wells drilled down to basalt clay layer (14-17 ...

  4. Development of a new software tool, based on ANN technology, in neutron spectrometry and dosimetry research

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J.M.; Martinez B, M.R.; Vega C, H.R. [Universidad Autonoma de Zacatecas, Av. Ramon Lopez Velarde 801, A.P. 336, 98000 Zacatecas (Mexico)

    2007-07-01

    Artificial Intelligence is a branch of study which enhances the capability of computers by giving them human-like intelligence. The brain architecture has been extensively studied and attempts have been made to emulate it as in the Artificial Neural Network technology. A large variety of neural network architectures have been developed and they have gained wide-spread popularity over the last few decades. Their application is considered as a substitute for many classical techniques that have been used for many years, as in the case of neutron spectrometry and dosimetry research areas. In previous works, a new approach called Robust Design of Artificial Neural network was applied to build an ANN topology capable to solve the neutron spectrometry and dosimetry problems within the Mat lab programming environment. In this work, the knowledge stored at Mat lab ANN's synaptic weights was extracted in order to develop for first time a customized software application based on ANN technology, which is proposed to be used in the neutron spectrometry and simultaneous dosimetry fields. (Author)

  5. A generalized calibration procedure for in vivo transit dosimetry using siemens electronic portal imaging devices.

    Science.gov (United States)

    Fidanzio, Andrea; Greco, Francesca; Gargiulo, Laura; Cilla, Savino; Sabatino, Domenico; Cappiello, Massimo; Di Felice, Cinzia; Di Castro, Elisabetta; Azario, Luigi; Russo, Mariateresa; Pompei, Luciano; D'Onofrio, Guido; Piermattei, Angelo

    2011-03-01

    A practical and accurate generalized in vivo dosimetry procedure has been implemented for Siemens linacs supplying 6, 10, and 15 MV photon beams, equipped with aSi electronic portal imaging devices (EPIDs). The in vivo dosimetry method makes use of correlation ratios between EPID transit signal, s (t) (0) (TPR,w,L), and phantom mid-plane dose, D (0)(TPR,w,L), as functions of phantom thickness, w, square field dimensions, L, and tissue-phantom ratio TPR(20,10). The s (t) (0) (TPR,w,L) and D (0)(TPR,w,L) values were defined to be independent of the EPID sensitivity and monitor unit calibration, while their dependence on TPR(20,10) was investigated to determine a set of generalized correlation ratios to be used for beams with TPR(20,10) falling in the examined range. This way, other radiotherapy centers can use the method with no need to locally perform the whole set of measurements in solid water phantoms, required to implement it. Tolerance levels for 3D conformal treatments, ranging between ±5 and ±6% according to tumor type and location, were estimated for comparison purposes between reconstructed isocenter dose, D (iso), and treatment planning system (TPS) computed dose D (iso,TPS). Finally a dedicated software, interfaceable with record and verify (R&V) systems used in the centers, was developed to obtain in vivo dosimetry results in less than 2 min after beam delivery.

  6. Physical aspects of scintigraphy-based dosimetry for nuclear medicine therapy

    Energy Technology Data Exchange (ETDEWEB)

    Geworski, L.; Knoop, B.O. [Dept. of Radiation Protection and Medical Physics, Hannover Medical School, Hannover (Germany); Schaefer, A.; Kirsch, C.M. [Dept. of Nuclear Medicine, Saarland Univ. Medical Center, Homburg (Germany); Pinkert, J. [Bayer Vital GmbH, Leverkusen (Germany); Plotkin, M. [Clinic for Nuclear Medicine, Univ. Hospital Charitee, Berlin (Germany)

    2010-07-01

    In nuclear medicine therapy the treatment of tumours by radiation exposure from internally deposited labelled antibodies or labelled peptides is currently an active field of investigation. To permit the efficient delivery of high amounts of radiation dose to tumours while limiting the radiation dose to critical organs dosimetry calculations have to be performed. These are relying on scintigraphic data being input to the well known MIRD formalism. This paper focuses on the methods and the difficulties associated with the scintigraphic determination of organ kinetics. The physical properties of the well-known scintigraphic imaging modalities, PET, SPECT and planar scintigraphy, are discussed thereby taking into account the properties of the appropriate radionuclides currently being available for therapy and dosimetry. Several arguments are given and disputed for the limited clinical use of PET and SPECT in dosimetry and the ongoing preference of planar whole-body imaging as the method of choice. The quantitative restrictions still inherent to this method are also discussed in detail. Procedural recommendations are proposed covering all processes related to data acquisition, data correction and data analysis which finally lead to reliable estimations of organ dose. (orig.)

  7. A novel optical calorimetry dosimetry approach applied to an HDR Brachytherapy source

    Science.gov (United States)

    Cavan, A.; Meyer, J.

    2013-06-01

    The technique of Digital Holographic Interferometry (DHI) is applied to the measurement of radiation absorbed dose distribution in water. An optical interferometer has been developed that captures the small variations in the refractive index of water due to the radiation induced temperature increase ΔT. The absorbed dose D is then determined with high temporal and spatial resolution using the calorimetric relation D=cΔT (where c is the specific heat capacity of water). The method is capable of time resolving 3D spatial calorimetry. As a proof-of-principle of the approach, a prototype DHI dosimeter was applied to the measurement of absorbed dose from a High Dose Rate (HDR) Brachytherapy source. Initial results are in agreement with modelled doses from the Brachyvision treatment planning system, demonstrating the viability of the system for high dose rate applications. Future work will focus on applying corrections for heat diffusion and geometric effects. The method has potential to contribute to the dosimetry of diverse high dose rate applications which require high spatial resolution such as microbeam radiotherapy (MRT) or small field proton beam dosimetry but may potentially also be useful for interface dosimetry.

  8. Retrospective assessment of personnel neutron dosimetry for workers at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Fix, J.J.; Wilson, R.H.; Baumgartner, W.B.

    1996-09-01

    This report was prepared to examine the specific issue of the potential for unrecorded neutron dose for Hanford workers, particularly in comparison with the recorded whole body (neutron plus photon) dose. During the past several years, historical personnel dosimetry practices at Hanford have been documented in several technical reports. This documentation provides a detailed history of the technology, radiation fields, and administrative practices used to measure and record dose for Hanford workers. Importantly, documentation has been prepared by personnel whose collective experience spans nearly the entire history of Hanford operations beginning in the mid-1940s. Evaluations of selected Hanford radiation dose records have been conducted along with statistical profiles of the recorded dose data. The history of Hanford personnel dosimetry is complex, spanning substantial evolution in radiation protection technology, concepts, and standards. Epidemiologic assessments of Hanford worker mortality and radiation dose data were initiated in the early 1960s. In recent years, Hanford data have been included in combined analyses of worker cohorts from several Department of Energy (DOE) sites and from several countries through the International Agency for Research on Cancer (IARC). Hanford data have also been included in the DOE Comprehensive Epidemiologic Data Resource (CEDR). In the analysis of Hanford, and other site data, the question of comparability of recorded dose through time and across the respective sites has arisen. DOE formed a dosimetry working group composed of dosimetrists and epidemiologists to evaluate data and documentation requirements of CEDR. This working group included in its recommendations the high priority for documentation of site-specific radiation dosimetry practices used to measure and record worker dose by the respective DOE sites.

  9. Teledosimetry: Personal and Area Dosimetry Control in order to evaluate the risk in real time

    Energy Technology Data Exchange (ETDEWEB)

    Galan Montenegro, P.; Macias Jaen, J.; Bodineau Gil, C.; Sanchez Hidalgo, M.

    2004-07-01

    Telemedicine is now an essential part of Health care and so, in addition to the scientific programme in the Carlos Haya Hospital in Malaga, Physics Department is involved into a process of change about the vision as a new Health Centre of XXI Century: Knowledge Hospital, by digital architecture and digitally integrated in its world. The Integrating the Health care Enterprise is the model used in order to get a big grade of relationship between medical images and information system. This change must be done in colaboration between some Departments of our centre, because it is a multidisciplinary task. It is understood that Teledosimetry can be considered as an important part of Telemedicine in the Radiological Protection field for workers and general public. In order to get this objective, the first step since 2000 it has been to prepare the internal hospital network with personal dosimetry information. From here workers in our hospital can obtain their dosimetry information data in more than 300 computers and since 2003, from home too. For access, each one of all have got an user identification and a password and so it can be guaranteed the privacy. We transform dose data reported by CND (Dosimetry National Center) in a big and visible database in PHP4 and Javascript format. This process is marked of problems about all due to the big manipulated information. Our intention is to make a better and friendly control, customisable and in real-time of the information dosimetry by a modular monitoring system of electronic dosimeters by the web. These radiation detectors would be located in representatives places. (Author)

  10. Thermoluminescent analyses of mean photon energy of a field

    Energy Technology Data Exchange (ETDEWEB)

    Cavalieri, T. A.; De Paiva, F.; Fonseca, G.; Dalledone S, P. de T.; Yoriyaz, H., E-mail: tassio.cavalieri@usp.br [Instituto de Pesquisas Energeticas e Nucleares / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil)

    2014-08-15

    Nowadays a common method of dosimetry is utilize the thermoluminescent dosimetry (TLD) of LiF, where for pure gamma field is typically used the LiF or CaF{sub 2} TLDs and for mixed neutron and gamma field dosimetry is used the pair TLD-600/TLD-700. The difference between these three LiF TLDs is the amount of isotope {sup 6}Li in their composition. The isotope {sup 6}Li has a great cross section for thermal neutrons, making the TLD-600 sensitive to thermal neutrons beyond the radiation gamma. Whereas the TLD-700 is considered sensitive only for radiation gamma. Some studies showed an energetic dependence of these TLDs for gammas rays. So the goal of this work was study these energetic dependence of TLDs from the angular coefficient of their response versus dose calibration curves when they were irradiated in four fields with photons of different energies: 43 keV, 662 keV, 1.2 MeV, 3 MeV. In order to create the calibration curves TLD, it was performed three irradiations with distinct exposure times for each photon energy. These studies showed a different angular coefficient to each curve; demonstrate the energetic dependence of these TLDs. By simulation with Monte Carlo based code, MCNP-5, it was observed the deposited photon dose due to different photons energies. From these simulations, it was also possible to observe a difference of dose deposition in TLDs when they were exposed to the same dose provided from different photons energies. These work showed the previously study of photon energetic dependence of LiF TLDs. (Author)

  11. Air emissions of small-scale (< 10 MW) biomass boilers. Review of three field tests; Developpement d'un calorimetre a eau pour la dosimetrie au LNE-LNHB

    Energy Technology Data Exchange (ETDEWEB)

    Autret, E. [Agence de l' Environnement et de la Maitrise de l' Energie, ADEME, 49 - Angers (France)

    2011-01-15

    Objectives of greenhouse gases emission reduction, which encourages bio-energy development for heat purposes, are compatible with air-quality policies if the concept of clean biomass combustion is applied. This paper presents actual emission levels of atmospheric pollutants of small-scale (< 10 MW) biomass boilers from a review of three field tests carried out between 2007 and 2009. 31 biomass boilers have been audited to cover the large diversity of sites under operation in terms of fuels, power, flue-gas cleaning devices.. Results are compared to actual and forecasted regulations. The review shows that fuel quality and operation are key issues to ensure low emissions of organic pollutants (OC, VOC, CnHm, PCDD/F, PAH, PCB, HCB), SO{sub 2}, NO{sub x}, fine particulate matters, metallic compounds. Installation design (power, flue-gas cleaning techno logy) also has a major impact on organic pollutants and fine particulate matter emissions. A large majority of boilers have very low emission levels. Guidelines are finally stated to keep on promoting small-scale biomass boilers in order to be air-quality compatible and efficient to fight climate change. (author)

  12. Gallium nitride based thin films for photon and particle radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Markus

    2012-07-23

    Ionization chambers have been used since the beginning of the 20th century for measuring ionizing radiation and still represent the ''gold standard'' in dosimetry. However, since the sensitivity of the devices is proportional to the detection volume, ionization chambers are not common in numerous medical applications, such as imaging. In these fields, spatially resolved dose information is, beside film-systems, usually measured with scintillators and photo-multipliers, which is a relatively complex and expensive technique. For thus much effort has been focused on the development of novel detection systems in the last decades and especially in the last few years. Examples include germanium or silicon photoconductive detectors, MOSFETs, and PIN-diodes. Although for these systems, miniaturization for spatially resolved detection is possible, they suffer from a range of disadvantages. Characteristics such as poor measurement stability, material degradation, and/or a limited measurement range prevent routine application of these techniques in medical diagnostic devices. This work presents the development and evaluation of gallium nitride (GaN) thin films and heterostructures to validate their application in x-ray detection in the medical regime. Furthermore, the impact of particle radiation on device response was investigated. Although previous publications revealed relatively low energy absorption of GaN, it is possible to achieve very high signal amplification factors inside the material due to an appropriate sensor configuration, which, in turn, compensates the low energy absorption. Thus, gallium nitride can be used as a photo-conductor with ohmic contacts. The conductive volume of the sensor changes in the presence of external radiation, which results in an amplified measurement signal after applying a bias voltage to the device. Experiments revealed a sensitivity of the device between air kerma rates of 1 {mu}Gy/s and 20 mGy/s. In this range

  13. Monte Carlo simulations for heavy ion dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Geithner, O.

    2006-07-26

    Water-to-air stopping power ratio (s{sub w,air}) calculations for the ionization chamber dosimetry of clinically relevant ion beams with initial energies from 50 to 450 MeV/u have been performed using the Monte Carlo technique. To simulate the transport of a particle in water the computer code SHIELD-HIT v2 was used which is a substantially modified version of its predecessor SHIELD-HIT v1. The code was partially rewritten, replacing formerly used single precision variables with double precision variables. The lowest particle transport specific energy was decreased from 1 MeV/u down to 10 keV/u by modifying the Bethe- Bloch formula, thus widening its range for medical dosimetry applications. Optional MSTAR and ICRU-73 stopping power data were included. The fragmentation model was verified using all available experimental data and some parameters were adjusted. The present code version shows excellent agreement with experimental data. Additional to the calculations of stopping power ratios, s{sub w,air}, the influence of fragments and I-values on s{sub w,air} for carbon ion beams was investigated. The value of s{sub w,air} deviates as much as 2.3% at the Bragg peak from the recommended by TRS-398 constant value of 1.130 for an energy of 50 MeV/u. (orig.)

  14. Dosimetry of radium-223 and progeny

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, D.R. [Pacific Northwest National Lab., Richland, WA (United States); Sgouros, G. [Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    1999-01-01

    Radium-223 is a short-lived (11.4 d) alpha emitter with potential applications in radioimmunotherapy of cancer. Radium-223 can be complexed and linked to protein delivery molecules for specific tumor-cell targeting. It decays through a cascade of short-lived alpha- and beta-emitting daughters with emission of about 28 MeV of energy through complete decay. The first three alpha particles are essentially instantaneous. Photons associated with Ra-223 and progeny provide the means for tumor and normal-organ imaging and dosimetry. Two beta particles provide additional therapeutic value. Radium-223 may be produced economically and in sufficient amounts for widescale application. Many aspects of the chemistry of carrier-free isotope preparation, complexation, and linkage to the antibody have been developed and are being tested. The radiation dosimetry of a Ra-223-labeled antibody shows favorable tumor to normal tissue dose ratios for therapy. The 11.4-d half-life of Ra-223 allows sufficient time for immunoconjugate preparation, administration, and tumor localization by carrier antibodies before significant radiological decay takes place. If 0.01 percent of a 37 MBq (1 mCi) injection deposits in a one gram tumor mass, and if the activity is retained with a typical effective half-time (75 h), the absorbed dose will be 163 mGy MBq{sup {minus}1} (600 rad mCi{sup {minus}1}) administered. 49 refs., 5 figs., 2 tabs.

  15. DRDC Ottawa working standard for biological dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Segura, T.M.; Prud' homme-Lalonde, L. [Defence Research and Development Canada, Ottawa, Ontario (Canada); Thorleifson, E. [Health Canada, Gatineau, Quebec (Canada); Lachapelle, S.; Mullins, D. [JERA Consulting (Canada); Qutob, S. [Health Canada, Gatineau, Quebec (Canada); Wilkinson, D.

    2005-07-15

    This Standard provides quality assurance, quality control, and evaluation of the performance criteria for the purpose of accreditation of the Radiation Biology laboratory at Defence Research and Development Canada - Ottawa (DRDC Ottawa) using biological dosimetry to predict radiation exposure doses. The International Standard (ISO 19238) and the International Atomic Energy Association (IAEA) Technical Report Series No. 405 are used as guiding documents in preparation of this working document specific to the DRDC Ottawa Radiation Biology Laboratory. This Standard addresses: 1. The confidentiality of personal information, for the customer and the service laboratory; 2. The laboratory safety requirements; 3. The calibration sources and calibration dose ranges useful for establishing the reference dose-effect curves allowing the dose estimation from chromosome aberration frequency, and the minimum detection levels; 4. Transportation criteria for shipping of test samples to the laboratory; 5. Preparation of samples for analysis; 6. The scoring procedure for unstable chromosome aberrations used for biological dosimetry; 7. The criteria for converting a measured aberration frequency into an estimate of absorbed dose; 8. The reporting of results; 9. The quality assurance and quality control plan for the laboratory; and 10. Informative annexes containing examples of a questionnaire, instructions for customers, a data sheet for recording aberrations, a sample report and other supportive documents. (author)

  16. ISDD: A Computational Model of Particle Sedimentation, Diffusion and Target Cell Dosimetry for In Vitro Toxicity Studies

    Energy Technology Data Exchange (ETDEWEB)

    Hinderliter, Paul M.; Minard, Kevin R.; Orr, Galya; Chrisler, William B.; Thrall, Brian D.; Pounds, Joel G.; Teeguarden, Justin G.

    2010-11-30

    . As a consequence, in vitro hazard assessments utilizing mass-based exposure metrics have inherently high errors where particle number or surface areas target cells doses are believed to drive response. The gold standard for particle dosimetry for in vitro nanotoxicology studies should be direct experimental measurement of the cellular content of the studied particle. However, where such measurements are impractical, unfeasible, and before such measurements become common, particle dosimetry models such as ISDD provide a valuable, immediately useful alternative, and eventually an adjunct to such measurements.

  17. ISDD: A computational model of particle sedimentation, diffusion and target cell dosimetry for in vitro toxicity studies

    Directory of Open Access Journals (Sweden)

    Chrisler William B

    2010-11-01

    g/mL basis and target cell doses on a particle surface area or number basis can be as high as three to six orders of magnitude. As a consequence, in vitro hazard assessments utilizing mass-based exposure metrics have inherently high errors where particle number or surface areas target cells doses are believed to drive response. The gold standard for particle dosimetry for in vitro nanotoxicology studies should be direct experimental measurement of the cellular content of the studied particle. However, where such measurements are impractical, unfeasible, and before such measurements become common, particle dosimetry models such as ISDD provide a valuable, immediately useful alternative, and eventually, an adjunct to such measurements.

  18. Radiation Dosimetry for Quality Control of Food Preservation and Disinfestation

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne; Uribe, R.M.

    1983-01-01

    In the use of x and gamma rays and scanned electron beams to extend the shelf life of food by delay of sprouting and ripening, killing of microbes, and control of insect population, quality assurance is provided by standardized radiation dosimetry. By strategic placement of calibrated dosimeters...... speed) to meet changes that occur in product and source parameters (e.g. bulk density and radiation spectrum). Routine dosimetry methods and certain corrections of dosimetry data may be selected for the radiations used in typical food processes....

  19. Dosimetry of Auger emitters: Physical and phenomenological approaches

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, K.S.R.; Howell, R.W.; Rao, D.V.; Mylavarapu, V.B.; Kassis, A.I.; Adelstein, S.J.; Wright, H.A.; Hamm, R.N.; Turner, J.E.

    1987-01-01

    Recent radiobiological studies have demonstrated that Auger cascades can cause severe biological damage contrary to expectations based on conventional dosimetry. Several determinants govern these effects, including the nature of the Auger electron spectrum; localized energy deposition; cellular geometry; chemical form of the carrier; cellular localization, concentration, and subcellular distribution of the radionuclide. Conventional dosimetry is inadequate in that these considerations are ignored. Our results provide the basis for biophysical approaches toward subcellular dosimetry of Auger emitters in vitro and in vivo. 12 refs., 7 figs., 2 tabs.

  20. Radioluminescence dosimetry by scintillating fiber optics: the open challenges

    Science.gov (United States)

    Veronese, Ivan; Cantone, Marie Claire; Chiodini, Norberto; De Mattia, Cristina; Fasoli, Mauro; Mones, Eleonora; Vedda, Anna

    2013-09-01

    In the last decade, the interest in scintillating fiber optics for ionizing radiation monitoring is constantly increasing. Among the fields of possible applications of these sensors, radiation therapy represents a driving force for the research and development of new devices. In fact, the small dimensions of fiber optics based detectors, together with their realtime response, make these systems extremely promising both in quality assurance measurements of intensity modulated radiotherapy beams, and in in-vivo dosimetry. On the other hand, two specific aspects might represent limiting factors: (i) the "stem effect", that is the spurious luminescence originating as a consequence of the irradiation of the light guide, and (ii) the "memory effect", that is the radioluminescence sensitivity increase during prolonged exposition to ionizing radiation, typical of many scintillating materials. These two issues, representing the main challenges to face for the effective use of scintillating fiber as dosimeters in radiotherapy, were studied considering amorphous silica matrices prepared by sol-gel method and doped with europium. The origin of the stem effect was investigated by means of spectral measurements of the doped fibers irradiated with Xrays and electrons of different energies, field sizes and orientations. New approaches for removing the stem effect on the basis of the radioluminescent spectral analysis are presented and discussed. Furthermore, the causes and phenomenology of the memory effect are described, considering also the effect of dose accumulation with different dose rates and energies of ionizing radiation.

  1. Application of spherical diodes for megavoltage photon beams dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Barbés, Benigno, E-mail: bbarbes@unav.es [Servicio de Oncología Radioterápica, Clínica Universidad de Navarra, Avda. Pío XII, 36, E-31008 Pamplona, Navarra (Spain); Azcona, Juan D. [Department of Radiation Oncology, Stanford University, Stanford, California 94305 and Servicio de Oncología Radioterápica, Clínica Universidad de Navarra, Avda. Pío XII 36, E-31008 Pamplona, Navarra (Spain); Burguete, Javier [Departamento de Física y Matemática Aplicada, Facultad de Ciencias, Universidad de Navarra, Irunlarrea 1, E-31008 Pamplona, Navarra (Spain); Martí-Climent, Josep M. [Servicio de Medicina Nuclear, Clínica Universidad de Navarra, Avda. Pío XII 36, E-31008 Pamplona, Navarra (Spain)

    2014-01-15

    Purpose: External beam radiation therapy (EBRT) usually uses heterogeneous dose distributions in a given volume. Designing detectors for quality control of these treatments is still a developing subject. The size of the detectors should be small to enhance spatial resolution and ensure low perturbation of the beam. A high uniformity in angular response is also a very important feature in a detector, because it has to measure radiation coming from all the directions of the space. It is also convenient that detectors are inexpensive and robust, especially to performin vivo measurements. The purpose of this work is to introduce a new detector for measuring megavoltage photon beams and to assess its performance to measure relative dose in EBRT. Methods: The detector studied in this work was designed as a spherical photodiode (1.8 mm in diameter). The change in response of the spherical diodes is measured regarding the angle of incidence, cumulated irradiation, and instantaneous dose rate (or dose per pulse). Additionally, total scatter factors for large and small fields (between 1 × 1 cm{sup 2} and 20 × 20 cm{sup 2}) are evaluated and compared with the results obtained from some commercially available ionization chambers and planar diodes. Additionally, the over-response to low energy scattered photons in large fields is investigated using a shielding layer. Results: The spherical diode studied in this work produces a high signal (150 nC/Gy for photons of nominal energy of 15 MV and 160 for 6 MV, after 12 kGy) and its angular dependence is lower than that of planar diodes: less than 5% between maximum and minimum in all directions, and 2% around one of the axis. It also has a moderated variation with accumulated dose (about 1.5%/kGy for 15 MV photons and 0.7%/kGy for 6 MV, after 12 kGy) and a low variation with dose per pulse (±0.4%), and its behavior is similar to commercial diodes in total scatter factor measurements. Conclusions: The measurements of relative dose

  2. City of El Centro geothermal energy utility core field experiment. Final report, February 16, 1979-November 30, 1984

    Energy Technology Data Exchange (ETDEWEB)

    Province, S.G.; Sherwood, P.B.

    1984-11-01

    The City of El Centro was awarded a contract in late 1978 to cost share the development of a low to moderate temperature geothermal resource in the City. The resource would be utilized to heat, cool and provide hot water to the nearby Community Center. In December 1981, Thermal 1 (injector) was drilled to 3970 feet. In January 1982, Thermal 2 (producer) was drilled to 8510 feet. Before testing began, fill migrated into both wells. Both wells were cleaned out. A pump was installed in the producer, but migration of fill again into the injector precluded injection of produced fluid. A short term production test was undertaken and results analyzed. Based upon the analysis, DOE decided that the well was not useful for commercial production due to a low flow rate, the potential problems of continued sanding and gasing, and the requirement to lower the pump setting depth and the associated costs of pumping. There was no commercial user found to take over the wells. Therefore, the wells were plugged and abandoned. The site was restored to its original condition.

  3. High performance unipolar inverters by utilizing organic field-effect transistors with ultraviolet/ozone treated polystyrene dielectric

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Wei; Yu, Xinge; Fan, Huidong; Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2014-09-01

    High performance unipolar inverters based on a significant variation of threshold voltage (V{sub th}) of organic field-effect transistors (OFETs), which was realized by introducing UV/ozone (UVO) treatment to polystyrene (PS) dielectric, were fabricated. A controllable V{sub th} shift of more than 10 V was obtained in the OFETs by adjusting the UVO treating time, and the unipolar inverters exhibited inverting voltage near 1/2 driving voltage and a noise margin of more than 70% of ideal value. From the analysis of scanning electron microscopy, atom force microscopy, and X-ray photoelectron spectroscopy, the dramatic controllable V{sub th} of OFETs, which played a key role in high performance unipolar inverters, was attributed to the newly generated oxygen functional groups in the PS dielectric induced by UVO treatment.

  4. One click film (OCF) dosimetry system for routine QA

    Energy Technology Data Exchange (ETDEWEB)

    Kim, So Young; Yi, Byong Yong; Kim, Jong Hoon; Ahn, Seung Do; Lee, Sang Wook; Choi, Eun Kyoung [Asan Medical Center, College of Medicine, University of Ulsan, Seoul (Korea, Republic of); Joo, Kwan Sik [MyongJi University, Yongin (Korea, Republic of)

    2002-12-15

    To develop a practical film dosimetry system for routine Quality Assurance (QA). An One Click Film (OCF) Dosimetry system was designed to perform swift routine QA with functions including automatic fog value elimination, angle adjustment, automatic symmetry calculation, and realtime profile generation with the ability to display realtime three-dimensional dose distributions. The most frequently used functions for routine QA, such as the elimination of the fog value, conversion into an H and D curve, symmetry, and isodose distribution, can be achieved with only one click. Reliable results were achieved with the OCF dosimetry with simpler steps than other commercially available film dosimetry systems for routine QA. More research on the refined user interface will make this system be clinically useful.

  5. Software for evaluation of EPR-dosimetry performance.

    Science.gov (United States)

    Shishkina, E A; Timofeev, Yu S; Ivanov, D V

    2014-06-01

    Electron paramagnetic resonance (EPR) with tooth enamel is a method extensively used for retrospective external dosimetry. Different research groups apply different equipment, sample preparation procedures and spectrum processing algorithms for EPR dosimetry. A uniform algorithm for description and comparison of performances was designed and implemented in a new computer code. The aim of the paper is to introduce the new software 'EPR-dosimetry performance'. The computer code is a user-friendly tool for providing a full description of method-specific capabilities of EPR tooth dosimetry, from metrological characteristics to practical limitations in applications. The software designed for scientists and engineers has several applications, including support of method calibration by evaluation of calibration parameters, evaluation of critical value and detection limit for registration of radiation-induced signal amplitude, estimation of critical value and detection limit for dose evaluation, estimation of minimal detectable value for anthropogenic dose assessment and description of method uncertainty.

  6. Retrospective dosimetry analyses of reactor vessel cladding samples

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L. R.; Soderquist, C. Z. [Battelle Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Fero, A. H. [Westinghouse Electric Company, Cranberry Twp., PA 16066 (United States)

    2011-07-01

    Reactor pressure vessel cladding samples for Ringhals Units 3 and 4 in Sweden were analyzed using retrospective reactor dosimetry techniques. The objective was to provide the best estimates of the neutron fluence for comparison with neutron transport calculations. A total of 51 stainless steel samples consisting of chips weighing approximately 100 to 200 mg were removed from selected locations around the pressure vessel and were sent to Pacific Northwest National Laboratory for analysis. The samples were fully characterized and analyzed for radioactive isotopes, with special interest in the presence of Nb-93m. The RPV cladding retrospective dosimetry results will be combined with a re-evaluation of the surveillance capsule dosimetry and with ex-vessel neutron dosimetry results to form a comprehensive 3D comparison of measurements to calculations performed with 3D deterministic transport code. (authors)

  7. Proceedings of the third conference on radiation protection and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Swaja, R.E.; Sims, C.S.; Casson, W.H. [eds.

    1991-10-01

    The Third Conference on Radiation Protection and Dosimetry was held during October 21--24, 1991, at the Sheraton Plaza Hotel in Orlando, Florida. This meeting was designed with the objectives of promoting communication among applied, research, regulatory, and standards personnel involved in radiation protection, and providing them with sufficient information to evaluate their programs. To meet these objectives, a technical program consisting of more than 75 invited and contributed oral presentations encompassing all aspects of radiation protection was prepared. General topics considered in the technical session included external dosimetry, internal dosimetry, instruments, accident dosimetry, regulations and standards, research advances, and applied program experience. In addition, special sessions were held to afford attendees the opportunity to make short presentations of recent work or to discuss topics of general interest. Individual reports are processed separately on the database.

  8. Evaluation of the Gafchromic{sup Registered-Sign} EBT2 film for the dosimetry of radiosurgical beams

    Energy Technology Data Exchange (ETDEWEB)

    Larraga-Gutierrez, Jose M. [Laboratorio de Fisica Medica, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, Mexico D.F. 14269 (Mexico) and Unidad de Radioneurocirugia, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, C.P. 14269, Mexico D.F. 14269 (Mexico); Garcia-Hernandez, Diana [Laboratorio de Fisica Medica, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, Mexico D.F. 14269 (Mexico); Garcia-Garduno, Olivia A. [Laboratorio de Fisica Medica, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, Mexico D.F. 14269 (Mexico) and Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Unidad Legaria, Instituto Politecnico Nacional, Legaria 694, Mexico D.F. 11500 (Mexico); Galvan de la Cruz, Olga O. [Unidad de Radioneurocirugia, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, Mexico D.F. 14269 (Mexico); Ballesteros-Zebadua, Paola [Laboratorio de Fisica Medica, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, Mexico D.F. 14269 (Mexico) and Unidad de Radioneurocirugia, Instituto Nacional de Neurologia y Neurocirugia, Insurgentes Sur 3877, Mexico D.F. 14269 (Mexico); Esparza-Moreno, Karina P. [Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan, Toluca, Estado De Mexico 50180 (Mexico)

    2012-10-15

    Purpose: Radiosurgery uses small fields and high-radiation doses to treat intra- and extracranial lesions in a single session. The lack of a lateral electronic equilibrium and the presence of high-dose gradients in these fields are challenges for adequate measurements. The availability of radiation detectors with the high spatial resolution required is restricted to only a few. Stereotactic diodes and EBT radiochromic films have been demonstrated to be good detectors for small-beam dosimetry. Because the stereotactic diode is the standard measurement for the dosimetry of radiosurgical beams, the goal of this work was to perform measurements with the radiochromic film Gafchromic{sup Registered-Sign} EBT2 and compare its results with a stereotactic diode. Methods: Total scatter factors, tissue maximum, and off-axis ratios from a 6 MV small photon beams were measured using EBT2 radiochromic film in a water phantom. The film-measured data were evaluated by comparing it with the data measured with a stereotactic field diode (IBA-Dosimetry). Results: The film and diode measurements had excellent agreement. The differences between the detectors were less than or equal to 2.0% for the tissue maximum and the off-axis ratios. However, for the total scatter factors, there were significant differences, up to 4.9% (relative to the reference field), for field sizes less than 1.0 cm. Conclusions: This work found that the Gafchromic{sup Registered-Sign} EBT2 film is adequate for small photon beam measurements, particularly for tissue maximum and off-axis ratios. However, careful attention must be taken when measuring output factors of small beams below 1.0 cm due to the film's energy dependence. The measurement differences may be attributable to the film's active layer composition because EBT2 incorporates higher Z elements (i.e., bromide and potassium), hence revealing a potential energy dependence for the dosimetry of small photon beams.

  9. Magnetic hyperthermia dosimetry by biomechanical properties revealed in magnetomotive optical coherence elastography (MM-OCE) (Conference Presentation)

    Science.gov (United States)

    Huang, Pin-Chieh; Marjanovic, Marina; Spillman, Darold R.; Odintsov, Boris M.; Boppart, Stephen A.

    2016-03-01

    Magnetic nanoparticles (MNPs) have been utilized in magnetic hyperthermia to treat solid tumors. Under an appropriate AC magnetic field, energy can be transferred to the MNPs to heat up the intended tissue target while sparing non-targeted healthy tissue. However, a sensitive monitoring technique for the dose of MNP thermal therapy is desirable in order to prevent over-treatment and collateral injury. Typical hyperthermia dosimetry often relies on changes in imaging properties or temperature measurements based on the thermal distribution. Alternative dosimetric indicators can include the biomechanical properties of the tissue, reflecting the changes due to protein denaturation, coagulation, and tissue dehydration during hyperthermia treatments. Tissue stiffness can be probed by elastography modalities including MRI, ultrasound imaging, and optical coherence elastography (OCE), with OCE showing the highest displacement sensitivity (tens of nanometers). Magnetomotive optical coherence elastography (MM-OCE) is one type of OCE that utilizes MNPs as internal force transducers to probe the tissue stiffness. Therefore, we examined the feasibility of evaluating the hyperthermia dose based on the elasticity changes revealed by MM-OCE. Superparamagnetic MNPs were applied to ex vivo tissue specimens for both magnetic hyperthermia and MM-OCE experiments, where temperature and elastic modulus were obtained. A correlation between temperature rise and measured stiffness was observed. In addition, we found that with repetitive sequential treatments, tissue stiffness increased, while temperature rise remained relatively constant. These results potentially suggest that MM-OCE could indicate the irreversible changes the tissue undergoes during thermal therapy, which supports the idea for MM-OCE-based hyperthermia dosage control in future applications.

  10. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    OpenAIRE

    2016-01-01

    Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation f...

  11. Why is a high accuracy needed in dosimetry. [Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Lanzl, L.H.

    1976-01-01

    Dose and exposure intercomparisons on a national or international basis have become an important component of quality assurance in the practice of good radiotherapy. A high degree of accuracy of ..gamma.. and x radiation dosimetry is essential in our international society, where medical information is so readily exchanged and used. The value of accurate dosimetry lies mainly in the avoidance of complications in normal tissue and an optimal degree of tumor control.

  12. Basic principles in the radiation dosimetry of nuclear medicine.

    Science.gov (United States)

    Stabin, Michael; Xu, Xie George

    2014-05-01

    The basic principles of the use of radiation dosimetry in nuclear medicine are reviewed. The basic structure of the main mathematical equations are given and formal dosimetry systems are discussed. An extensive overview of the history and current status of anthropomorphic models (phantoms) is given. The sources and magnitudes of uncertainties in calculated internal dose estimates are reviewed. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. A practical three-dimensional dosimetry system for radiation therapy

    OpenAIRE

    Guo, Pengyi; Adamovics, John; Oldham, Mark

    2006-01-01

    There is a pressing need for a practical three-dimensional (3D) dosimetry system, convenient for clinical use, and with the accuracy and resolution to enable comprehensive verification of the complex dose distributions typical of modern radiation therapy. Here we introduce a dosimetry system that can achieve this challenge, consisting of a radiochromic dosimeter (PRESAGE™) and a commercial optical computed tomography (CT) scanning system (OCTOPUS™). PRESAGE™ is a transparent material with com...

  14. Stochastic method-based computational system for neutron/photon dosimetry applied to radiotherapy and radiology

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Bruno Machado; Campos, Tarcisio Passos Ribeiro de, E-mail: campos@nuclear.ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Program of Post-Graduation in Sciences and Nuclear Techniques

    2011-03-15

    Objective: The present paper describes a procedure for conversion of computed tomography or magnetic resonance images into a three-dimensional voxel model for dosimetry purposes. Such model is a personalized representation of the patient that can be utilized in nuclear particle transport simulations by means of the MCNP (Monte Carlo N-Particle) code, reproducing the stochastic process of nuclear particles interaction with human tissues. Materials and Methods: The developed computational system - SISCODES - is a tool designed for 3D planning of radiotherapy or radiological procedures. Based on tomographic images of the patient, the treatment plan is modeled and simulated. Then, the absorbed doses are shown by means of isodose curves superimposed on the model. The SISCODES couples the three dimensional model with the MCNP5 code, simulating the protocol of exposure to ionizing radiation. Results: The SISCODES has been utilized by the NRI/CNPq in the creation of anthropomorphic and anthropometric voxel models which are coupled with the MCNP code for modeling brachytherapy and teletherapy applied to lung, pelvis, spine, head and neck tumors, among others. The current SISCODES modules are presented together with examples of cases of radiotherapy planning. Conclusion: The SISCODES provides a fast method to create personalized voxel models of any patient which can be used in stochastic simulations. The combination of the MCNP simulation with a personalized model of the patient increases the dosimetry accuracy in radiotherapy. (author)

  15. Utility of galaxy catalogs for following up gravitational waves from binary neutron star mergers with wide-field telescopes

    CERN Document Server

    Hanna, Chad; Vousden, Will

    2013-01-01

    The first detections of gravitational waves from binary neutron star mergers with advanced LIGO and Virgo observatories are anticipated in the next five years. These detections could pave the way for multi-messenger gravitational-wave (GW) and electromagnetic (EM) astronomy if GW triggers are successfully followed up with targeted EM observations. However, GW sky localization is relatively poor, with expected localization areas of ~10--100 square degrees; this presents a challenge for following up GW signals from compact binary mergers. Prioritizing wide-field follow-ups based on the probability of successful imaging is important when it is impossible to tile the entire gravitational-wave localization region. Galaxy catalogs were effective at narrowing down regions of the sky to search in initial attempts at joint GW/EM observations. The next generation of GW detectors will have a ten-fold increase in range thereby increasing the expected number of galaxies per unit solid angle a thousand-fold. As an addition...

  16. Characterizing and hindcasting ripple bedform dynamics: Field test of non-equilibrium models utilizing a fingerprint algorithm

    Science.gov (United States)

    DuVal, Carter B.; Trembanis, Arthur C.; Skarke, Adam

    2016-03-01

    Ripple bedform response to near bed forcing has been found to be asynchronous with rapidly changing hydrodynamic conditions. Recent models have attempted to account for this time variance through the introduction of a time offset between hydrodynamic forcing and seabed response with varying success. While focusing on temporal ripple evolution, spatial ripple variation has been partly neglected. With the fingerprint algorithm ripple bedform parameterization technique, spatial variation can be quickly and precisely characterized, and as such, this method is particularly useful for evaluation of ripple model spatio-temporal validity. Using time-series hydrodynamic data and synoptic acoustic imagery collected at an inner continental shelf site, this study compares an adapted time-varying ripple geometric model to observed field observations in light of the fingerprint algorithm results. Multiple equilibrium ripple predictors are tested within the time-varying model, with the algorithm results serving as the baseline geometric values. Results indicate that ripple bedforms, in the presence of rapidly changing high-energy conditions, reorganize at a slower rate than predicted by the models. Relict ripples were found to be near peak-forcing wavelengths after rapidly decaying storm events, and still present after months of sub-critical flow conditions.

  17. A new standard cylindrical graphite-walled ionization chamber for dosimetry in 60Co beams at calibration laboratories

    Science.gov (United States)

    Neves, Lucio P.; Perini, Ana P.; Caldas, Linda V. E.

    2014-11-01

    60Co sources are used mostly at dosimetry laboratories for calibration of ionization chambers utilized for radiotherapy dosimetry, mainly in those laboratories where there is no linear accelerator available. In this work, a new cylindrical ionization chamber was developed and characterized to be used as a reference dosimeter at the Calibration Laboratory of the IPEN. The characterization tests were performed according to the IEC 60731 standard, and all tests presented results within its recommended limits. Furthermore, the correction factors for the wall, stem, central collecting electrode, nonaxial uniformity and the mass-energy absorption coefficient were determined using the EGSnrc Monte Carlo code. The air kerma rate determined with this new dosimeter was compared to the one obtained with the IPEN standard, presenting a difference of 1.5%. Therefore, the new ionization chamber prototype developed and characterized in this work presents potential use as a primary standard dosimeter at radiation metrology laboratories.

  18. Individual dosimetry of workers and patients: implementation and perspectives; La dosimetrie individuelle des travailleurs et de patients: mise en oeuvre et perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Rannou, A.; Aubert, B.; Lahaye, Th.; Scaff, P.; Casanova, Ph.; Van Bladel, L.; Queinnec, F.; Valendru, N.; Jehanno, J.; Grude, E.; Berard, Ph.; Desbree, A.; Kafrouni, H.; Paquet, F.; Vanhavere, F.; Bridier, A.; Ginestet, Ch.; Magne, S.; Donadille, L.; Bordy, J.M.; Bottollier-Depois, J.F.; Barrere, J.L.; Ferragut, A.; Metivier, H.; Gaillard-Lecanu, E

    2008-07-01

    These days organised by the section of the technical protection of the S.F.R.P. review the different techniques of dosimetry used in France and Europe, and present the future orientations.The different interventions are as follow: Individual exposures of the workers: historic assessment and perspectives; medical exposure: where are the doses; legal obligations in individual dosimetry: which are the objective and the need on the subject; the dosimetry follow-up of workers by the S.I.S.E.R.I. system: assessment and perspectives; impact of the norm ISO 20553 on the follow-up of internal exposure; the implementation of the patient dose measurement in Belgium; techniques of passive dosimetry used in Europe; Supervision radiation protection at EDF: long term and short term approach; Comparison active and passive dosimetry at Melox; methodology for the choice of new neutron dosemeters; the working group M.E.D.O.R.: guide of internal dosimetry for the use of practitioners; O.E.D.I.P.E.: tool of modeling for the personalized internal dosimetry; the use of the Monte-Carlo method for the planning of the cancer treatment by radiotherapy becomes a reality; the works of the committee 2 of the ICRP; passive dosimetry versus operational dosimetry: situation in Europe; Implementation of the in vivo dosimetry in a radiotherapy department: experience of the Gustave Roussy institute; experience feedback on the in vivo measures in radiotherapy, based on the use of O.S.L. pellets; multi points O.S.L. instrumentation for the radiation dose monitoring in radiotherapy; dosimetry for extremities for medical applications: principle results of the European contract C.O.N.R.A.D.; references and perspectives in dosimetry; what perspectives for numerical dosimetry, an example: Sievert; system of dose management: how to answer to needs; the last technical evolutions in terms of electronic dosimetry in nuclear power plant; the fourth generation type reactors: what dosimetry. (N.C.)

  19. The radiation dosimetry of intrathecally administered radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Stabin, M.G. [Oak Ridge Inst. for Science and Education, TN (United States); Evans, J.F. [Ohio State Univ., Columbus, OH (United States)

    1999-01-01

    The radiation dose to the spine, spinal cord, marrow, and other organs of the body from intrathecal administration of several radiopharmaceuticals was studied. Anatomic models were developed for the spine, spinal cerebrospinal fluid (CSF), spinal cord, spinal skeleton, cranial skeleton, and cranial CSF. A kinetic model for the transport of CSF was used to determine residence times in the CSF; material leaving the CSF was thereafter assumed to enter the bloodstream and follow the kinetics of the radiopharmaceutical as if intravenously administered. The radiation transport codes MCNP and ALGAMP were used to model the electron and photon transport and energy deposition. The dosimetry of Tc-99m DTPA and HSA, In-111 DTPA, I-131 HSA, and Yb-169 DTPA was studied. Radiation dose profiles for the spinal cord and marrow in the spine were developed and average doses to all other organs were estimated, including dose distributions within the bone and marrow.

  20. Accidental neutron dosimetry with human hair

    Science.gov (United States)

    Ekendahl, Daniela; Bečková, Věra; Zdychová, Vlasta; Bulánek, Boris; Prouza, Zdeněk; Štefánik, Milan

    2014-11-01

    Human hair contains sulfur, which can be activated by fast neutrons. The 32S(n,p)32P reaction with a threshold of 2.5 MeV was used for fast neutron dose estimation. It is a very important parameter for individual dose reconstruction with regards to the heterogeneity of the neutron transfer to the human body. Samples of human hair were irradiated in a radial channel of a training reactor VR-1. 32P activity in hair was measured both, directly by means of a proportional counter, and as ash dispersed in a liquid scintillator. Based on neutron spectrum estimation, a relationship between the neutron dose and induced activity was derived. The experiment verified the practical feasibility of this dosimetry method in cases of criticality accidents or malevolent acts with nuclear materials.

  1. EPR tooth dosimetry of SNTS area inhabitants

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, Sergey [Scientific Center for Radiation Medicine, Melnikova str., 53, Kiev (Ukraine); Desrosiers, Marc [Ionizing Radiation Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Bouville, Andre; Luckyanov, Nicholas [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Bethesda, MD (United States); Chumak, Vadim [Scientific Center for Radiation Medicine, Melnikova str., 53, Kiev (Ukraine); Simon, Steven L. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Bethesda, MD (United States)], E-mail: ssimon@mail.nih.gov

    2007-07-15

    The determination of external dose to teeth of inhabitants of settlements near the Semipalatinsk Nuclear Test Site (SNTS) was conducted using the EPR dosimetry technique to assess radiation doses associated with exposure to radioactive fallout from the test site. In this study, tooth doses have been reconstructed for 103 persons with all studied teeth having been formed before the first nuclear test in 1949. Doses above those received from natural background radiation, termed 'accident doses', were found to lie in the range from zero to approximately 2 Gy, with one exception, a dose for one person from Semipalatinsk city was approximately 9 Gy. The variability of reconstructed doses within each of the settlements demonstrated heterogeneity of the deposited fallout as well as variations in lifestyle. The village mean external gamma doses for residents of nine settlements were in the range from a few tens of mGy to approximately 100 mGy.

  2. Dosimetry for radiocolloid therapy of cystic craniopharyngiomas

    CERN Document Server

    Rojas, E L; Lallena, A M; Bodineau, C; Galan, P; Al-Dweri, Feras M.O.; Lallena, Antonio M.; Bodineau, Coral; Galan, Pedro

    2003-01-01

    The dosimetry for radiocolloid therapy of cystic craniopharyngiomas is investigated. Analytical calculations based on the Loevinger and the Berger formulae for electrons and photons, respectively, are compared with Monte Carlo simulations. The role of the material of which the colloid introduced inside the craniopharyngioma is made of as well as that forming the cyst wall is analyzed. It is found that the analytical approaches provide a very good description of the simulated data in the conditions where they can be applied (i.e., in the case of a uniform and infinite homogeneous medium). However, the consideration of the different materials and interfaces produces a strong reduction of the dose delivered to the cyst wall in relation to that predicted by the Loevinger and the Berger formulae.

  3. EPR-dosimetry with carious teeth

    Energy Technology Data Exchange (ETDEWEB)

    Sholom, S.V. E-mail: sholom@leed1.kiev.ua; Haskell, E.H.; Hayes, R.B.; Chumak, V.V.; Kenner, G.H

    2000-12-15

    The effect of caries in EPR dosimetry of tooth enamel (in the dose range of 0-1 Gy) was investigated. The enamel of each tooth was divided into carious, non-carious and intermediate portions. The EPR signals of enamel at g=2.0018 (dosimetric) and g=2.0045 (native) were examined. The intensity of the dosimetric signal was the same for all three portions, while that of the native signal was higher for carious portions than for non-carious and intermediate portions. Reconstruction of the laboratory applied doses was done using all portions. Reasonable correlation between nominal and reconstructed doses was found in most cases. The effect of alkali treatment on the native and dosimetric signals of enamel was also tested. Reduction of the native signal intensity, particularly in the carious portions, was found to be the only significant effect. This resulted in a slight improvement in the accuracy of the reconstructed doses.

  4. In vivo dosimetry during tangential breast treatment

    Energy Technology Data Exchange (ETDEWEB)

    Heukelom, S.; Lanson, J.H.; Tienhoven, G. van; Mijnheer, B.J. (Nederlands Kanker Inst. ' Antoni van Leeuwenhoekhuis' , Amsterdam (Netherlands))

    1991-12-01

    Three-dimensional (3-D) dose distribution as calculated in clinical practice for tangential breast treatment was verified through in vivo dosimetry. Clinical practice at Netherlands Cancer Institute implies use of 8MV X-ray beams, 2-D treatment planning system, collimator rotation and a limited set of patient data for dose calculations. By positioning diodes at the central beam axes as well as in the periphery of the breast the magnitude of dose values at the isocentre and in points situated in high-dose regions behind the lung could be assessed. The position of diodes was verified by means of an on-line portal imaging device. Reproducibility of these in vivo dose measurements was better than 2% (1SD). This study shows that on the average dose delivery at the isocentre is 2% less at the points behind the lung, 5.7% higher with respect to the calculated dose values. Detailed analysis of these in vivo dosimetry results, based on dose measurements performed with a breast shaped phantom, yielded the magnitudes of errors in predicted dose due to several limitations in dose calculation algorithms and dose calculation procedure. These limitations are each introducing an error of several percent but are compensating each other for the dose calculation at the isocentre. It is concluded that dose distribution in patient for this treatment technique and dose calculation procedure can be predicted with a 2-D treatment planning system in an acceptable way. A more accurate prediction of dose distribution can be performed but requires an estimation of the lack of scatter due to missing tissue, the change in the dose distribution due to oblique incident beams and incorporation of the actual output of the treatment machine in the assessment of the number of monitor units. (author). 28 refs.; 3 figs.; 4 tabs.

  5. Fast neutron activation dosimetry with TLDS

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, D.W.; Moran, P.R.

    1975-01-01

    Fast neutron activation using threshold reactions is the only neutron dosimetry method which offers complete discrimination against gamma-rays and preserves some information about the neutron energy. Conventional activation foil technique requires sensitive radiation detectors to count the decay of the neutron induced activity. For extensive measurements at low neutron fluences, vast outlays of counting equipment are required. TL dosimeters are inexpensive, extremely sensitive radiation detectors. The work of Mayhugh et al. (Proc. Third Int. Conf. on Luminescence Dosimetry, Riso Report 249, 1040, (1971)) showed that CaSO/sub 4/: DyTLDs could be used to measure the integrated dose from the decay of the radioactivity produced in the dosimeters by exposure to thermal neutrons. This neatly combines the activation detector and counter functions in one solid state device. This work has been expanded to fast neutron exposures and other TL phosphors. The reactions /sup 19/F(n, 2n)/sup 18/F, /sup 32/S(n,p)/sup 32/P, /sup 24/Mg(n,p)/sup 24/, and /sup 64/Zn(n,p)/sup 64/Cu were found useful for fast neutron activation in commercial TLDs. As each TLD is its own integrating decay particle counter, many activation measurements can be made at the same time. The subsequent readings of the TL signals can be done serially after the induced radioactivity has decayed, using only one TL reader. The neutron detection sensitivity is limited mainly by the number statistics of the neutron activations. The precision of the neutron measurement is within a factor of two of conventional foil activation for comparable mass detectors. Commercially available TLDs can measure neutron fluences of 10/sup 9/n/cm/sup 2/ with 10 percent precision.

  6. High sensitive radiation detector for radiology dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Valente, M.; Malano, F. [Instituto de Fisica Enrique Gaviola, Oficina 102 FaMAF - UNC, Av. Luis Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina); Molina, W.; Vedelago, J., E-mail: valente@famac.unc.edu.ar [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2014-08-15

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

  7. Personal Dosimetry Enhancement for Underground Workplaces

    Directory of Open Access Journals (Sweden)

    L. Thinová

    2005-01-01

    Full Text Available Personal dosimetry for underground workers mainly concerns measurement of the concentration of radon (and its daughters and the correct application of the data in dose calculation, using a biokinetic model for lung dosimetry. A conservative approach for estimating the potential dose in caves (or underground is based on solid state alpha track detector measurements. The obtained dataset is converted into an annual effective dose in agreement with the ICRP recommendations using the “cave factor”, the value of which depends on the spectrum of aerosol particles, or on the proportional representation of the unattached and the attached fraction and on the equilibrium factor. The main difference between apartments and caves is the absence of aerosol sources, high humidity, low ventilation rate and the uneven surface in caves. A more precisely determined dose value would have a significant impact on radon remedies or on restricting the time workers stay underground. In order to determine  how the effective dose is calculated, it is necessary to divide these areas into distinct categories by the following measuring procedures: continual radon measurement (to capture the differences in EERC between working hours and night-time, and also between daily and seasonal radon concentration variations; regular measurements of radon and its daughters to estimate the equilibrium factor and the presence of 218Po; regular indoor air flow measurements to study the location of the radon supply and its transfer among individual areas of the cave; natural radioactive element content evaluation in subsoils and in water inside/outside, a study of the radon sources in the cave; aerosol particle-size spectrum measurements to determine the free fraction; monitoring the behaviour of guides and workers to record the actual time spent in the cave, in relation to the continuously monitored levels of Rn concentration. 

  8. Effect of contrast agent administration on consequences of dosimetry and biology in radiotherapy planning

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Ching-Jung [Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, 259 Wen-Hua 1st Road, Kwei-Shan, Tao-Yuan 333 Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Kwei-Shan, Tao-Yuan 333 Taiwan (China); Yang, Pei-Ying [Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, 259 Wen-Hua 1st Road, Kwei-Shan, Tao-Yuan 333 Taiwan (China); Chao, Tsi-Chian, E-mail: chaot@mail.cgu.edu.tw [Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, 259 Wen-Hua 1st Road, Kwei-Shan, Tao-Yuan 333 Taiwan (China); Tu, Shu-Ju,