Science.gov

Sample records for harshaw tld-700h dosemeters

  1. The dose-response of Harshaw TLD-700H.

    PubMed

    Velbeck, K J; Luo, L Z; Ramlo, M J; Rotunda, J E

    2006-01-01

    Harshaw TLD-700H (7LiF:Mg,Cu,P) was previously characterised for low- to high-dose ranges from 1 microGy to 20 Gy. This paper describes the studies and results of dose-response and linearity at much higher doses. TLD-700H is a near perfect dosimetric material with near tissue equivalence, flat energy response, and the ability to measure beta, gamma and X rays. These new results extend the applicability of Harshaw TLD-700H into more dosimetric measurement environments. The simple glow curve structure provides insignificant fade, eliminating special oven preparation methods experienced by other materials. The work presented in this paper quantifies the performance of Harshaw TLD-700H in extended ranges. PMID:16581931

  2. Type testing of an extremity finger stall dosemeter based on Harshaw TLD EXTRAD technology.

    PubMed

    Gilvin, P J; Luo, L Z; Baker, S T; Hill, C E; Rotunda, J E

    2007-01-01

    A new type of extremity dosemeter, which incorporates the Harshaw TLD EXTRAD dosemeter element into a PVC finger stall, has been developed. The dosemeter uses high-sensitivity lithium fluoride, (7)LiF:Mg,Cu,P (TLD-700H) in a thin 7 mg cm(-2) layer, with alternative coverings of PVC at 10 mg cm(-2) and aluminised polyester at 3.2 mg cm(-2). Results are presented of the type testing of both versions of the finger stall dosemeter against published standards. PMID:17132668

  3. Performance of Harshaw TLD-100H two-element Dosemeter.

    PubMed

    Luo, L Z; Rotunda, J E

    2006-01-01

    One of the advantages of LiF based thermoluminescent (TL) materials is its tissue-equivalent property. The Harshaw TLD-100H (LiF:Mg,Cu,P) material has demonstrated that it has a near-flat photon energy response and high sensitivity. With the optimized dosemeter filters built into the holder, the Harshaw TLD-100H two-element dosemeter can be used as a whole body personnel dosemeter for gamma, X ray and beta monitoring without the use of an algorithm or correction factor. This paper presents the dose performance of the Harshaw TLD-100H two-element dosemeter against the ANSI N13.11-2001 standard and the results of tests that are required in IEC 1066 International Standard. PMID:16644944

  4. Pre-irradiation and post-irradiation fading of the Harshaw 8841 TLD in different environmental conditions.

    PubMed

    Jones, L A; Stokes, R P

    2007-01-01

    The pre-irradiation and post-irradiation fading of a commercially available LiF:Mg,Cu,P thermoluminescent detector (TLD)-the Harshaw 8841 TLD-have been assessed. The Harshaw 8841 TLD comprises three TLD-700H chips (99.7% 7LiF and 0.03% 6LiF by weight) and one TLD-600H chip (4.4% 7LiF and 95.6% 6LiF by weight). Pre-irradiation and post-irradiation fading were measured for storage times up to 164 d and three different storage temperatures (-8, 25 and 50 degrees C). Dosemeters were irradiated in a mixed photon-neutron field so that the fading behaviour of the photon and neutron signals could be studied. The TLD-700H and TLD-600H chips exhibited complex changes in sensitivity and signal that depended on storage time, storage temperature and the type of radiation to which the chips had been exposed. However, the magnitudes of these changes in sensitivity and signal were relatively small. TLD-600H and TLD-700H, therefore, exhibit good stability of sensitivity and signal. PMID:17008363

  5. Response of Harshaw neutron thermoluminescence dosemeters in terms of the revised ICRP/ICRU recommendations.

    PubMed

    Veinot, K G; Hertel, N E

    2005-01-01

    To monitor workers for external neutron radiation dose, the Y-12 National Security Complex utilises the thermoluminescence dosemeters (TLDs) manufactured by Harshaw. At Y-12, the majority of external dose to workers is due to low-energy photon and/or beta particles emitted from uranium and its progeny. However, some neutron dose is expected since neutrons are produced from (alpha,n) reactions in various compounds found at the plant, including UF4 and UF6. Neutron sources, such as 252Cf, are also used throughout the complex. The Harshaw neutron dosemeter consists of two gamma-sensitive elements (7Li) and two neutron-sensitive elements enriched in 6Li with various shielding/filter materials placed around each of them. In this work, the energy response of the dosemeter to neutrons has been calculated using the Monte Carlo transport code MCNP Version 4-C and, these results are compared with the measured response of the dosemeter to unmoderated and D2O-moderated 252Cf neutrons. The response of the dosemeter has also been determined in terms of the personal absorbed dose and personal dose equivalent as a function of neutron energy based on the recommendations of the ICRP Publication 60 and ICRU Report 49. The energy response of the dosemeter characteristics can be used to generate spectral conversion coefficients for routine neutron absorbed dose and dose equivalent calculations. PMID:15788417

  6. The MCNP-4C2 design of a two element photon/electron dosemeter that uses magnesium/copper/phosphorus doped lithium fluoride.

    PubMed

    Eakins, J S; Bartlett, D T; Hager, L G; Molinos-Solsona, C; Tanner, R J

    2008-01-01

    The Health Protection Agency is changing from using detectors made from 7LiF:Mg,Ti in its photon/electron personal dosemeters, to 7LiF:Mg,Cu,P. Specifically, the Harshaw TLD-700H card is to be adopted. As a consequence of this change, the dosemeter holder is also being modified not only to accommodate the shape of the new card, but also to optimize the photon and electron response characteristics of the device. This redesign process was achieved using MCNP-4C2 and the kerma approximation, electron range/energy tables with additional electron transport calculations, and experimental validation, with different potential filters compared; the optimum filter studied was a polytetrafluoroethylene disc of diameter 18 mm and thickness 4.3 mm. Calculated relative response characteristics at different angles of incidence and energies between 16 and 6174 keV are presented for this new dosemeter configuration and compared with measured type-test results. A new estimate for the energy-dependent relative light conversion efficiency appropriate to the 7LiF:Mg,Cu,P was also derived for determining the correct dosemeter response. PMID:17951605

  7. Energy and directional response for the Harshaw dosemeter holders 8814 and 8891, and its effect on the appropriate radiation qualities for absolute calibration.

    PubMed

    Børretzen, I; Wøhni, T

    2003-01-01

    The personal dosimetry laboratory at the Norwegian radiation protection authority utilises a two-element dosemeter card for measuring Hp(10) and Hp(0.07), in a Harshaw dosemeter holder type 8814. Energy and directional responses for photons and betas for this holder have been assessed, as well as for the new Harshaw holder type 8891. The energy response characteristics for the 12-1250 keV photon energy range, in terms of TL output per unit Hp(10) and Hp(0.07) have been evaluated. The maximum over-response to under-response ratio for the Hp(10) element was found to be 1.46 for the new type 8891 holder, as compared to 1.55 for the older type 8814. The new holder also displays a more favourable directional response for this element. For the Hp(0.07) element, no significant differences with regard to energy or directional responses were found. Selecting radiation energy for absolute calibration of the Hp(10) and Hp(0.07) elements are discussed. PMID:12596986

  8. The study of new calibration features in the Harshaw TLD system.

    PubMed

    Luo, L Z

    2007-01-01

    The Harshaw TLD system has three key calibration procedures: the Reader, the Dosemeter and the Algorithm. These functions must be properly calibrated for the system to achieve the optimum results. For the conventional reader and dosemeter calibration, Harshaw TLD recommends a pre-fade and a post-fade of 24-48 h when calibrating the system for LiF:Mg,Ti type dosemeter. It is also recommended that keeping the fade time consistent is important to maintain the quality of the system performance. In recent years, new calibration features have been introduced into the Harshaw TLD models 6600 and 8800 operating systems. These new features are Auto Calibration, Auto QC and Auto Blank, and they give the user the ability to set up the clear-expose-read process to be performed automatically in a sequence for each dosemeter. This saves processing time and keeps the fade time the same. However, since the fade time is near zero, will it affect the TLD system calibration factors? What should the user expect? This paper presents a study of the effect of Auto Calibration/Auto QC to the TLD operation. PMID:17223631

  9. Personal photon dosemeter trial--Devonport Royal Dockyard.

    PubMed

    Collison, Roger

    2005-03-01

    To establish an understanding of the operational responses of various personal dosemeters employed at Devonport and to assess new types of dosemeters, a photon dosemeter trial was conducted. Most day-to-day exposure is to relatively low dose rates. Therefore the suitability of each dosemeter for use within the relatively low Devonport dose rate environment has been assessed. The Panasonic TLD demonstrated a good representation of the dose within the medium to higher gamma energy ranges with an unexpected under-response at lower energies. The optically stimulated luminescent dosemeter showed a varied response within a degraded (60)Co environment. With consistent under-response, the NRPB TLD and film badge were found to generally be unsuitable for sites such as Devonport. The Harshaw TLD demonstrated a good representation of the dose. The RADOS RAD80 and QFD fail to meet current best industry standards. However, the QFD is the only direct reading dosemeter suitable for use where intrinsically safe equipment is required. The RADOS RAD52 and SAIC PD 2i show a reasonable representation of the dose received but should be adjusted to read within an operational (60)Co environment. Direct ion storage and Thermo [corrected] electronic personal dosemeters showed good representations of the dose. Inherent characteristics combined with the associated systems led to the conclusion that these dosemeters should be employed for preference. PMID:15798276

  10. Comparison of the effects of exposure to light in Harshaw LiF:Mg,Ti and LiF:Mg,Cu,P.

    PubMed

    Baker, S T; Gilvin, P J

    2007-01-01

    The response of thermoluminescence dosemeters (TLDs) to light, in various conditions, has been studied. TLD cards containing both conventional lithium fluoride (LiF:Mg,Ti) and the high-sensitivity material LiF:Mg,Cu,P were available, so permitting a comparison between the two types. Also available for the tests were Harshaw extremity EXT-RAD (LiF:Mg,Cu,P) dosemeters. The LiF:Mg,Ti body TLD cards and the EXT-RAD extremity dosemeters both showed some response to fluorescent light, while the LiF:Mg,Cu,P cards showed no significant response. It is therefore concluded that LiF:Mg,Cu,P body cards need no special precautions to protect them from the effects of light. For LiF:Mg,Ti cards and extremity dosemeters, effects are small, but steps to avoid excessive light exposure should be considered. PMID:16980318

  11. Passive Neutron Dosemeter Design

    NASA Astrophysics Data System (ADS)

    Becerra-Ferrerio, Ana Mara; Vega-Carrillo, Hctor Ren

    2002-08-01

    A passive neutron dosemeter was designed to be used in mixed radiation fields. The design was carried out using Monte Carlo method. The dosemeter model was a 25.4 cmdiameter polyethylene sphere with a thermoluminescent dosemeter, TLD600, located at the sphere center. This model was irradiated with 50 monoenergetic neutron sources with energies from 10-8 to 20 MeV. A 506.71 cm2-area disk was used to model the source term whose center was located at 100 cm from polyethylene sphere's center. The dosemeter response was compared with the responses of SNOOPY, Harwell 95/0075 and PNR-4. With these responses it was calculated the dosemeter responses for 252Cf, 252Cf/D2O and 239PuBe neutron sources. The passive dosemeter relative response has the same shape of SNOOPY, Harwell 95/0075 and PNR-4 dosemeters. Due to the type of thermal neutron detector used in the passive dosemeter the absolute response per unit fluence, is lower than the absolute response of SNOOPY, Harwell 95/0075 and PNR-4 dosemeters. However the passive dosemeter response in function of the average neutron energy of the 252Cf, 252Cf/D2O and 239PuBe neutron energy was more linear.

  12. Thermoluminescence dosimetry of a thermal neutron field and comparison with Monte Carlo calculations.

    PubMed

    Fernandes, A C; Santos, J P; Kling, A; Marques, J G; Gonçalves, I C; Carvalho, A Ferro; Santos, L; Cardoso, J; Osvay, M

    2004-01-01

    The characteristics of thermoluminescence dosemeters (TLDs) regarding the determination of photon and neutron absorbed doses were investigated in a thermal neutron beam. Harshaw TLD-100 (LiF:Mg,Ti) and TLD-700 (7LiF:Mg,Ti) were compared with similar materials from Solid Dosimetric Detector and Method Laboratory (People's Republic of China). Harshaw TLD-700H (7LiF:Mg,Cu,P) and aluminium oxide (Al2O3:Mg,Y) from Hungary were also considered for photon dose measurement. The neutron sensitivity of the investigated materials was measured and found to be consistent with values reported by other authors. A comparison was made between the TL dose measurements and results obtained via conventional methods. An agreement within 20% was obtained, which demonstrates the ability of TLD for measuring neutron and photon doses in a mixed field, using careful calibration procedures and determining the neutron sensitivity for the usage conditions. PMID:15367765

  13. Type testing the Model 6600 plus automatic TLD reader.

    PubMed

    Velbeck, K J; Luo, L Z; Streetz, K L

    2006-01-01

    The Harshaw Model 6600 Plus is a reader with a capacity for 200 TLD cards or 800 extremity cards. The new unit integrates more functionality, and significantly automates the QC and calibration process compared to the Model 6600. The Model 6600 Plus was tested against the IEC 61066 (1991-2012) procedures using Harshaw TLD-700H and TLD-600H, LiF:Mg,Cu,P based TLD Cards. An overview of the type testing procedures is presented. These include batch homogeneity, detection threshold, reproducibility, linearity, self-irradiation, residue, light effects on dosemeter, light leakage to reader, voltage and frequency, dropping and reader stability. The new TLD reader was found to meet all the IEC criteria by large margins and appears well suited for whole body, extremity and environmental dosimetry applications, with a high degree of dosimetric performance. PMID:16835278

  14. Comparison of time effects, decision limit and residual signal in Harshaw LiF:Mg,Ti and LiF:Mg,Cu,P.

    PubMed

    Gilvin, P J

    2007-01-01

    The personal dosimetry service of the UK Health Protection Agency--formerly of the National Radiological Protection Board (NRPB)--is currently commissioning a body thermoluminescence dosemeter (TLD) system based on the use of Harshaw 8800 readers and two-element cards. As part of the process, studies have been carried out into the long-term time dependence of response, the limit of detection and the magnitude of the signal remaining after recommended processing. TLD cards containing both conventional lithium fluoride (LiF:Mg,Ti) and the high-sensitivity material LiF:Mg,Cu,P were available, thus allowing a comparison between the two types of material. PMID:17293354

  15. Inter-comparison among different TLD-based techniques in a standard multisphere assembly for the characterisation of neutron fields.

    PubMed

    Bedogni, R; Angelone, M; Esposito, A; Chiti, M

    2006-01-01

    In the framework of collaboration among the ENEA Radiation Protection Institute (Bologna), the ENEA Fusion Department (Frascati) and the INFN-LNF-Radiation Protection Group (Frascati), an experimental campaign was organised on the usage of thermoluminescence dosemeters (TLDs) for the dosimetric and spectrometric characterisation of neutron fields. Commercially available TLDs of different material and different sensitivity to photons and thermal neutrons were selected, namely TLD600H and TLD700H from Harshaw, GR206 and GR207 from SSDML (China), MCP-6s from TLD Poland. The detectors were first calibrated in standard fields of photons ((60)Co) and thermal neutrons at the ENEA-IRP Secondary Standard Calibration Laboratory of Bologna, then exposed in fast neutron standard fields of different energy, using a standard multisphere moderating assembly. The paper compares the dosimetric characteristics of the studied TL detectors, underlining the (n-gamma) discrimination capability, and discusses their spectrometric performances addressed to radiation protection applications. PMID:16709710

  16. Dosimetric properties of new cards with high-sensitivity MCP-N (LiF:Mg,Cu,P) detectors for Harshaw automatic reader.

    PubMed

    Budzanowski, M; Bilski, P; Olko, P; Ryba, E; Perle, S; Majewski, M

    2007-01-01

    A new configuration for a thermoluminescent dosimetric card has been developed through collaboration between the Institute of Nuclear Physics in Kraków and several commercial dosimetric companies. The card is based on high-sensitivity LiF:Mg,Cu,P circular pellets (MCP-N) welded inside synthetic foils. The basic configuration consists of two pellets of 3.6 mm diameter and thicknesses from 0.25 up to 0.38 mm. The cards can be processed in a standard 6600 or 8800 Harshaw automatic TLD reader. The dosemeters demonstrate very high sensitivity, low background and good stability. This article presents results of the performance tests of the new dosimetric cards in the automatic TLD readers and a comparison of their properties. PMID:17020912

  17. UV-induced bleaching of deep traps in Harshaw TLD LiF:Mg,Cu,P and LiF:Mg,Ti.

    PubMed

    Benevides, L; Voss, S; Nita, I; Rotunda, J; Velbeck, K; Luo, L Z; Moscovitch, M

    2011-03-01

    The effects of UV-induced bleaching of deep traps on Harshaw thermoluminescent (TL) LiF:Mg,Cu,P and LiF:Mg,Ti materials were investigated. During a normal heating cycle, LiF:Mg,Cu,P is limited to a maximum temperature of 240 °C. LiF:Mg,Ti can be read to higher temperatures; however, encapsulation in polytetrafluoroethylene limits the maximum readout temperature to 300 °C. Generally, for both materials, these respective temperatures are sufficient for emptying traps corresponding to the main dosemetric peaks. However, when the dosemeters are subjected to a high dose level, such as 1 Gy (much higher than individual monitoring dose levels), higher temperature traps are filled that cannot be emptied without exceeding the above-mentioned maximum temperatures. These high temperature traps tend to be unstable during normal readout and can significantly increase the residual TL signal. The purpose of this study was to investigate the applicability of a UV-induced bleaching technique for emptying higher temperature traps following high-dose applications. In addition, in the case of LiF:Mg,Cu,P, where the maximum readout temperature is significantly lower, we investigated the possibility of reducing the residual signal using the application of repeated readout cycles. The optical bleaching approach was found to be effective in the case of LiF:Mg,Ti; however, for LiF:Mg,Cu,P, no reduction in the residual signal was observed. For this latter material, the application of repeatable readout cycles is very effective and residual signals equivalent to dose levels as low as 0.01 mGy were observed following an initial dose of 5 Gy. To the best of our knowledge, this work is the first attempt to apply an 'optical annealing' technique to the Harshaw thermoluminescent dosemeter (TLD) materials. PMID:21310735

  18. The implementation in routine of the ENEA new personal photon dosemeter.

    PubMed

    Fantuzzi, E; Mariotti, F; Morelli, B; Uleri, G

    2006-01-01

    The ENEA photon dosemeter, introduced in 1995, consisting of two differently filtrated LiF(Mg,Cu,P) detectors, has been modified recently. The ABS (acrylonitrile butadiene styrene) plastic support has been replaced by a new aluminium card supporting the same two detectors (LiF(Mg,Cu,P) GR200). The new card, fully developed at the ENEA-Radiation Protection Institute (which is going to be patented), can now be processed through a Harshaw Model 6600 Automated TLD Reader, a hot gas reader. This paper reports the results of the individual calibration of approximately 60,000 LiF(Mg,Cu,P) GR200 detectors inserted on the new aluminium cards. Before the implementation in routine of the new cards, the reader has been characterised. Steps and tests to be made to use the card in routine (i.e. reader stability, linearity, reproducibility, etc.) are reported. The whole dosimetric system now combines the very good performances of the Harshaw Model 6600 reader and that of LiF(Mg,Cu,P) thermoluminescent material. PMID:16644988

  19. Review of international standards for dosemeters.

    PubMed

    Behrens, R; Ambrosi, P

    2008-01-01

    International standards for radiation protection dosemeters are published by the International Electrotechnical Commission and the International Organization for Standardization. Several standards exist side by side, although they treat the same measuring task, and specify different requirements, so that dosemeters of different quality result. In this paper, the quality of dosemeters is compared by calculating the uncertainty of dose measurements for dosemeters, which just basely fulfil the respective standard. The results are related to general yardsticks on uncertainty laid down by international organisations. Furthermore, technical differences are standards and addressed and a method to make them conform is presented. PMID:17627960

  20. An adapter for the Harshaw model 2000D TL analyzer system

    NASA Astrophysics Data System (ADS)

    Gupta, Virendra P.; Cusimano, John P.; Parker, DeRay

    A potentially more versatile personnel radiation dosimetry badge, using TLD LiF-700 and LiF-600 chips, has been under development at the INEL. To read all four TLD chips from this badge without removing (or placing back after reading) one chip at a time, a unique adapter has been developed to provide the capability of reading chips in a Harshaw Model 2000D Automated TL Analyzer System. Only slight modification of the Harshaw Analyzer is required for using this adapter.

  1. Optimization of the readout procedures for the Harshaw 8800 TL (thermoluminescent) dosimetry system

    SciTech Connect

    Liu, Chwei-jeng; Sims, C.S.; Rhea, T.A.

    1989-07-01

    The optimization of the readout procedures for Harshaw's LiF-TLDs and it 8800 automatic TLD reader were studied. The optimization was based on the TLD sensitivity stability during 8-10 recycling uses. Three types of TLDs under several exposure conditions (gamma and neutron, low and high doses, and different fading times), five different types of TL light signals, and three different heating time-temperature-profiles (TTPs) were involved in the stability performance studies. The results show that the optimum readout procedures for all exposure cases can be achieved by using the Harshaw-suggested TTP heating methods and the TL light signals of some certain carefully-chosen regions of interest and peaks 3+4+5. The practical experience gained from using the computerized glow curve deconvolution (CGCD) program in the reader is also discussed. 17 refs., 5 figs., 6 tabs.

  2. Optimization of the readout procedures for the Harshaw 8800 automatic TL dosimetry system

    SciTech Connect

    Liu, J.; Sims, C.S.; Rhea, T.A. )

    1989-08-01

    The optimization of the readout procedures for Harshaw's LiF-TLDs and 8800 automatic TAD reader were studied. The optimization was mainly based on the TAD sensitivity stability performance during 8-10 recycling uses. These types of LiF-TLDs under several exposure conditions (gamma and neutron, low and high doses, and different fading times), five different types of TL light signals, and three different time-temperature profile (TTP) heating methods were involved in the stability performance studies. The results sow that the optimum readout procedures for all exposure cases can be achieved by using the Harshaw suggested TTP heating methods and the TL light signals of certain carefully chosen regions of interest, and TL signal of peaks 3 + 4 + 5. In this paper the practical experience gained from using the computerized glow curve deconvolution program to derive the TL signals of some peak areas is presented.

  3. Evaluation of Effective Sources in Uncertainty Measurements of Personal Dosimetry by a Harshaw TLD System

    PubMed Central

    Hosseini Pooya, SM; Orouji, T

    2014-01-01

    Background: The accurate results of the individual doses in personal dosimety which are reported by the service providers in personal dosimetry are very important. There are national / international criteria for acceptable dosimetry system performance. Objective: In this research, the sources of uncertainties are identified, measured and calculated in a personal dosimetry system by TLD. Method: These sources are included; inhomogeneity of TLDs sensitivity, variability of TLD readings due to limited sensitivity and background, energy dependence, directional dependence, non-linearity of the response, fading, dependent on ambient temperature / humidity and calibration errors, which may affect on the dose responses. Some parameters which influence on the above sources of uncertainty are studied for Harshaw TLD-100 cards dosimeters as well as the hot gas Harshaw 6600 TLD reader system. Results: The individual uncertainties of each sources was measured less than 6.7% in 68% confidence level. The total uncertainty was calculated 17.5% with 95% confidence level. Conclusion: The TLD-100 personal dosimeters as well as the Harshaw TLD-100 reader 6600 system show the total uncertainty value which is less than that of admissible value of 42% for personal dosimetry services. PMID:25505769

  4. Fast neutron dosemeter using pixelated detector Timepix.

    PubMed

    Bulanek, Boris; Ekendahl, Daniela; Prouza, Zdenek

    2014-10-01

    A Timepix detector covered with polyethylene convertors of different thicknesses is presented as a fast neutron real-time dosemeter. The application of different weighting factors in connection with the position of a signal in a Timepix detector enables one to obtain an energy-dependent signal equal to neutron dose equivalents. A simulation of a Timepix detector covered with polyethylene convertors using monoenergetic neutrons is presented. The experimental set-up of a dosemeter was also produced. The first results of detector response using different fast neutron sources are presented. PMID:24277875

  5. Using operational equipment to read accident dosemeters.

    PubMed

    Devine, R T; Vigil, M M; Martinez, W A

    2004-01-01

    Analysis of accident dosemeters usually involves the use of laboratory-based counting equipment. Gamma spectrometers are used for indium, copper and gold, and alpha-beta detectors for sulphur. This equipment is usually not easily transported due to the shielding required and the weight and delicacy of the counters. For intercomparison studies that require reading the dosemeters on site, a transportable system is required unless the site operating the study can count samples for all the participants. In the case of an actual accident these systems would have a difficulty in counting a large number of accident dosemeters. In an accident, personnel are usually subdivided according to their level of exposure. Those exposed to higher doses are treated immediately. An alternate system should be made available to handle the dosemeters worn by those personnel are likely to receive lower doses. Improvements in portable operational equipment for gamma and beta monitoring allow their use as spectrometers. Such a system was used for the SILENE intercomparison conducted at IRSN Valduc on 12 June and 19, 2002, and the preliminary results compared well with the other participants. PMID:15353733

  6. Health Hazard Evaluation Report HETA 84-128-1601, Harshaw/Filtrol, Louisville, Kentucky

    SciTech Connect

    London, M.; Lee, S.A.; Morawetz, J.

    1985-06-01

    Environmental and breathing-zone samples were analyzed for 3,3'-dichlorobenzidine (DCB) and ortho-dianisidine (ODA) at Harshaw/Filtrol, Louisville, Kentucky in August, 1984. The evaluation was requested by the union to investigate possible exposures to suspected bladder carcinogens. Urine and skin samples were obtained from four potentially exposed workers and analyzed for ODA and DCB. The authors conclude that a potential health hazard exists due to ODA exposure at the facility. DCB does not pose a health risk. Recommendations include improving housekeeping and decontamination procedures for DCB, handling ODA as a suspect carcinogen by applying appropriate engineering controls and using personal protective equipment, and performing periodic monitoring for urinary DCB and ODA.

  7. [Inaccuracy in the acquisition of glowcurves with the TL-Reader Harshaw 5500].

    PubMed

    Polivka, Bernd; Lüpke, Matthias; Seifert, Herrmann; Karstens, Johann-Hinrich

    2006-01-01

    Putting into operation a TL Reader Type Harshaw 5500 revealed some inaccuracies in the acquisition of glowcurves, i.e., a shift of the glowcurves upon exposure to different temperatures in sequential measurements. These inaccuracies hinder a precise analysis of parts of the glowcurves with easy methods. The present investigation focused on the analysis of possible causes for these observations. It was found out that one requirement for a reproducible data acquisition is the stability and precise positioning of the thermoluminescence dosimeter in the heating position. These conditions allow constant heating and therefore a stable glowcurve concerning the temperature. The accuracy of glowcurve acquisition could be clearly improved with mechanical changes of the TL Reader. Long-term observations are still required. PMID:16875029

  8. A new, passive dosemeter for gamma, beta and neutron radiations.

    PubMed

    Jones, L A; Stokes, R P

    2011-03-01

    The Defence Science and Technology Laboratory (Dstl) provides personal radiation dosimetry to the UK Ministry of Defence. Dstl has recently developed a dosemeter that is based on a combination of thermoluminescent and etched-track detectors. The Dstl Combined Dosemeter is capable of assessing doses due to photons, beta particles and neutrons. This paper presents the laboratory type testing results for the Combined Dosemeter, and also describes the procedure for calibrating the dosemeter for use in workplace neutron fields. The Combined Dosemeter meets the type test requirements that are relevant to its intended applications, and gives neutron doses that are within 50% of the true dose in the workplaces in which it is used, even when the wearer has the potential to be exposed to a variety of neutron spectra (e.g. on board nuclear-powered submarines). PMID:21346288

  9. Calibration of Far West Technology (FWT-60) radiachromic dye dosemeters

    SciTech Connect

    Mincher, B.J.; Zaidi, M.K.

    1992-01-01

    Radiachromic dye dosimetry was used to measure kilogray doses absorbed by various liquid samples during gamma-ray exposure in a spent nuclear fuel pool. The source of nuclear fuel was the Advanced Test Reactor (ATR) at the Idaho National Engineering Laboratory (INEL). Calibrations were performed using a {sup 60}Co source and were run on bare dosemeters, as well as on dosemeters which mocked to simulate the samples. These dosemeters were prepared as a dye-impregnated nylon film and are commercially available. When exposed to gamma-ray doses of 0.5 to 200 kGy, a color change occurs which has an optical density proportional to absorbed dose. The difference in the calibration curves demonstrated the importance of irradiation of dosemeters under conditions as close to the actual samples as possible. Since these dosemeters could not be immersed directly in the organic solutions of interest, they were sandwiched between layers of lucite and stainless steel. This simulated the conditions inside an irradiated sample and provides a practical method of measuring absorbed doses. The reproducibility of measurements using the radiachromic dye dosemeters is also shown. 10 refs.

  10. Calibration of Far West Technology (FWT-60) radiachromic dye dosemeters

    SciTech Connect

    Mincher, B.J.; Zaidi, M.K.

    1992-08-01

    Radiachromic dye dosimetry was used to measure kilogray doses absorbed by various liquid samples during gamma-ray exposure in a spent nuclear fuel pool. The source of nuclear fuel was the Advanced Test Reactor (ATR) at the Idaho National Engineering Laboratory (INEL). Calibrations were performed using a {sup 60}Co source and were run on bare dosemeters, as well as on dosemeters which mocked to simulate the samples. These dosemeters were prepared as a dye-impregnated nylon film and are commercially available. When exposed to gamma-ray doses of 0.5 to 200 kGy, a color change occurs which has an optical density proportional to absorbed dose. The difference in the calibration curves demonstrated the importance of irradiation of dosemeters under conditions as close to the actual samples as possible. Since these dosemeters could not be immersed directly in the organic solutions of interest, they were sandwiched between layers of lucite and stainless steel. This simulated the conditions inside an irradiated sample and provides a practical method of measuring absorbed doses. The reproducibility of measurements using the radiachromic dye dosemeters is also shown. 10 refs.

  11. Further studies in the reduction of residual in Harshaw TLD-100H (LiF:Mg,Cu,P).

    PubMed

    Ramlo, M; Moscovitch, M; Rotunda, J E

    2007-01-01

    This paper describes further investigations and results in the reduction of residual signal in Harshaw TLD-100H, 600H and 700H (LiF:Mg,Cu,P). TLD-100H is an advanced, relatively new dosimetric material with near tissue-equivalence, flat energy response, and the ability to measure beta, photon and, more importantly, neutrons all from the same base material. The simple glow curve structure provides insignificant fade over extended dosimetric periods of up to 1 y. A criticism of the material has been the residual as compared with TLD-100 (LiF:Mg,Ti). We will show how high-temperature peaks cause the residual signal. We will also show how the various parameters and conditions of the residual measurement technique as well as the configuration of the sample affect the residual measurements. A brief description of the experimental paths taken during our investigation will be presented. We will show how we have reduced the high-temperature peaks of LiF:Mg,Cu,P in our manufacturing process while not affecting other dosimetric properties of this material. The improvements and material properties that need to be shown have been incorporated into our production processes. LiF:Mg,Cu,P stands as a premier choice for personal dosimetry and has been integrated into personal, environmental and extremity configurations of the Harshaw TLD family-line of products. PMID:17416592

  12. The possible effect on personnel dose by two copper filters covering Element 1 of the Harshaw 8814 TLD badge.

    PubMed

    Reciniello, R N; Sengupta, S; Thompson, R L

    2009-08-01

    Ongoing uncertainties have existed regarding possible effects at low photon energies of two copper filters covering Element 1 of the Harshaw Type-8814 thermoluminescent dosimeter badge casing. To address these, Brookhaven National Laboratory's (BNL) Personnel Monitoring Group conducted a test in which Type-8814 badges with one copper filter covering Element 1 were irradiated at several low-energy levels side-by-side with the same number of badges with two copper filters covering Element 1. A review of exposures to personnel at Brookhaven Laboratory to possible low-energy photon flux was also conducted. From both the test and the review of exposures, it can be concluded that, for radiological work under the conditions at BNL, there is no apparent dosimetric difference if one or two copper filters cover Element 1 of the Type-8814 badge. PMID:19590267

  13. The applicability of the PTTL dose re-analysis method to the Harshaw LiF:Mg,Cu,P material.

    PubMed

    Moscovitch, M; Benevides, L; Romanyukha, A; Hull, F; Duffy, M; Voss, S; Velbeck, K J; Nita, I; Rotunda, J E

    2011-03-01

    The phototransferred thermoluminescence (PTTL) technique is applied to the Harshaw LiF:Mg,Cu,P material. It is demonstrated that using 254-nm UV light, dose levels as low as 0.2 mGy can be re-estimated. The PTTL efficiency was found to be ∼ 6 % in the dose range of 0.2 mGy-1 Gy, and it appears to be dose-independent. This implies that a simple calibration factor could be applied to the PTTL data for the re-estimation of dose levels. It was demonstrated that with a proper choice of the TL readout parameters, and the UV-light irradiation conditions, dose levels that are relevant to personal or environmental dosimetry can be re-estimated. PMID:21450701

  14. Preliminary survey report: control technology for manual transfer of chemical powders at Harshaw Filtrol Partnership, Louisville, Kentucky

    SciTech Connect

    Godbey, F.W.

    1984-08-01

    Health-hazard control measures, work processes, and existing control technologies used in the manual transfer of chemical powders were evaluated at Harshaw Filtrol Partnership, Louisville, Kentucky in May, 1984. The company employed 180 workers to produce inorganic and organic colors for the paint, printing, and coatings industries. The major dry ingredients were cadmium, selenium, lead, molybdenum, and chrome. Colors were made by mixing water and solid materials together in tanks from which the finished product was precipitated out. Solid materials were metered out from storage tanks or dumped from large bags into the mixer tanks. The precipitated finished product was metered from the mixer into bags and other containers. Local and general exhaust ventilation was provided along with safety glasses, hard hats, respirators, face shields, and protective clothing. Workers received health and safety training and were encouraged to use good work practices.

  15. Formerly utilized MED/AEC sites remedial action program. Radiological survey of the Harshaw Chemical Company, Cleveland, Ohio

    SciTech Connect

    Wynveen, R.A.; Smith, W.H.; Sholeen, C.M.; Justus, A.L.; Flynn, K.F.

    1984-04-01

    During the MED/AEC era, the Harshaw Chemical Company processed large quantities of normal uranium to produce both oxide and fluoride compounds. This work was done under contract to MED and its successor, AEC. Records indicated that at the time the AEC contract was terminated, the facility was decontaminated by Harshaw and released from AEC control in 1960. However, a search of AEC records indicated that documentation was insufficient to determine whether the decontamination work was adequate by current guidelines. Hence, a radiological assessment of the site ws initiated in 1976. The entire grounds and all buildings were surveyed using surface survey instruments to detect surface contamination and radiation detectors to determine general radiation levels. Extensive surface contamination was found throughout the site. While the major contamination was found in Plant C, significant levels of contamination also were found in 16 other buildings and at 32 exterior locations. The contaminating material seemed to be normal uranium exclusively. Air samples were taken at numerous indoor locations throughout the site, but no elevated levels of radon were detected. This was as expected since normal uranium has been separated from radium and hence radon levels are very low. Several soil samples were taken from around the site. Analyses of these samples indicated extensive soil contamination, as well as suspected contamination of the river bed in the vicinity of the plant outfall. Scheduled subsurface investigation of the site, as well as of the river bed and sewer system, have not been conducted. Levels of contamination at this site are significantly above guidelines for release of the site for unrestricted use. 57 figures, 7 tables.

  16. Multisphere default spectra--solution spectrum and dosemeter response implications.

    PubMed

    Mallett, M W; McLean, T D; Olsher, R H; Romero, L L; Seagraves, D T; Devine, R T; Eisele, S L; Hoffman, J M; Murphy, R O

    2004-01-01

    Initial calibration of a multisphere spectroscopy system has been completed at Los Alamos National Laboratory using four standard calibration scenarios. Spectrum unfolding was performed using three methods of constructing the default spectrum: simple parameter models, Monte Carlo calculations and physical measurement. Comparisons of the resulting spectra for each solution method are presented. Implications of the spectral solutions upon dosemeter characterisation are addressed. PMID:15353707

  17. Empirical-theoretical determination of the neutron response function for Teflon encapsulated TLD-600 using the Harshaw Model 8800 hot-gas reader

    NASA Astrophysics Data System (ADS)

    Buckner, M. A.

    1994-07-01

    The neutron energy response of Teflon encapsulated TLD-600, processed by a Harshaw Model 8800 hot-gas reader, has been determined using a combined experimental and theoretical approach. The agreement between theoretically predicted responses and experimental data for the three radioisotopic spectra evaluated was within 0.1%. The method used to determine the response functions, the response functions themselves, and the theoretical and experimental results are presented.

  18. Radiochromic gel dosemeter for three-dimensional dosimetry

    NASA Astrophysics Data System (ADS)

    Bero, M. A.; Gilboy, W. B.; Glover, P. M.

    2001-06-01

    A gel dosemeter in which ionising radiation causes a colour change was produced by modifying an existing Fricke gel system. This allows a more convenient preparation procedure and gives a better quality dosimetric system for three-dimensional (3-D) dose measurements. The role of three active components of the Ferrous sulphate Xylenol orange Gelatin (FXG) gel dosemeter is quantified with special consideration of their effect on system sensitivity and stability. The optimal composition was found to be 0.5 mM ferrous sulphate, 0.1 mM xylenol orange and 25 mM sulphuric acid. The dose response is linear in the range 0.1-30 Gy. The FXG sensitivity, derived from the gradient of the dose response curve, was found to be ΔA=0.084 cm -1 Gy -1, where A is the optical absorption coefficient at a wavelength of 585 nm, with reproducibility and 24 h stability of better than 5%.

  19. A method for evaluating personal dosemeters in workplace with neutron fields.

    PubMed

    de Freitas Nascimento, Luana; Cauwels, Vanessa; Vanhavere, Filip

    2012-04-01

    Passive detectors, as albedo or track-etch, still dominate the field of neutron personal dosimetry, mainly due to their low-cost, high-reliability and elevated throughput. However, the recent appearance in the market of electronic personal dosemeters for neutrons presents a new option for personal dosimetry. In addition to passive detectors, electronic personal dosemeters necessitate correction factors, concerning their energy and angular response dependencies. This paper reports on the results of a method to evaluate personal dosemeters for workplace where neutrons are present. The approach here uses few instruments and does not necessitate a large mathematical workload. Qualitative information on the neutron energy spectrum is acquired using a simple spectrometer (Nprobe), reference values for H*(10) are derived from measurements with ambient detectors (Studsvik, Berthold and Harwell) and angular information is measured using personal dosemeters (electronic and bubbles dosemeters) disposed in different orientations on a slab phantom. PMID:21565843

  20. Monte Carlo modelling of a simple accident dosemeter.

    PubMed

    Devine, R T

    2005-01-01

    A simple dosemeter made of a sulphur tablet, bare and cadmium-covered indium foils and a cadmium-covered copper foil has been modelled using MCNP5. Studies of the model without phantoms or other confounding factors have shown that the cross sections and fluence-to-dose factors generated by the Monte Carlo method agree with those generated by analytic expressions for the high-energy component. In this study, the effect of location on phantoms is studied and an extension of this study to low and intermediate energies is done. The activities expected from exposure to four critical assemblies on phantom is calculated and compared with observations. PMID:16604683

  1. New concept of IEC standards for radiation protection dosemeters.

    PubMed

    Ambrosi, P; Behrens, R

    2008-01-01

    The International Electrotechnical Commission (IEC) develops new standards for radiation protection dosemeters which follow a new concept. They are much more flexible in detail, but still ensure the same measurement quality. They are, for example, no longer specific for the detector type, but rather specific for the measurement task, e.g. for individual monitoring with active direct-reading instruments. Another example is that they are flexible with respect to the ranges of influence quantities. The conceptual changes are described in this paper, together with the advantages this new concept provides for manufacturers, users and legislators. PMID:18420572

  2. Monte Carlo modelling of a simple accident dosemeter.

    TOXLINE Toxicology Bibliographic Information

    Devine RT

    2005-01-01

    A simple dosemeter made of a sulphur tablet, bare and cadmium-covered indium foils and a cadmium-covered copper foil has been modelled using MCNP5. Studies of the model without phantoms or other confounding factors have shown that the cross sections and fluence-to-dose factors generated by the Monte Carlo method agree with those generated by analytic expressions for the high-energy component. In this study, the effect of location on phantoms is studied and an extension of this study to low and intermediate energies is done. The activities expected from exposure to four critical assemblies on phantom is calculated and compared with observations.

  3. Tupe testing of the Siemens Plessey electronic personal dosemeter

    SciTech Connect

    Hirning, C.R.; Yuen, P.S.

    1995-07-01

    This paper presents the results of a laboratory assessment of the performance of a new type of personal dosimeter, the Electronic Personal Dosemeter made by Siemens Plessey Controls Limited. Twenty pre-production dosimeters and a reader were purchased by Ontario Hydro for the assessment. Tests were performed on radiological performance, including reproducibility, accuracy, linearity, detection threshold, energy response, angular response, neutron response, and response time. There were also tests on the effects of a variety of environmental factors, such as temperature, humidity, pulsed magnetic and electric fields, low- and high-frequency electromagnetic fields, light exposure, drop impact, vibration, and splashing. Other characteristics that were tested were compared with the relevant requirements of three standards: an Ontario Hydro standard for personal alarming dosimeters, an International Electrotechnical Commission draft standard for direct reading personal dose monitors, and an International Electrotechnical Commission standard for thermoluminescence dosimetry systems for personal monitoring. In general, the performance of the Electronic Personal Dosemeter was found to be quite acceptable: it met most of the relevant requirements of the three standards. However, the following deficiencies were found: slow response time; sensitivity to high-frequency electromagnetic fields; poor resistance to dropping; and an alarm that was not loud enough. In addition, the response of the electronic personal dosimeter to low-energy beta rays may be too low for some applications. Problems were experienced with the reliability of operation of the pre-production dosimeters used in these tests. 11 refs., 8 figs., 24 tabs.

  4. Type testing of the Siemens Plessey electronic personal dosemeter.

    PubMed

    Hirning, C R; Yuen, P S

    1995-07-01

    This paper presents the results of a laboratory assessment of the performance of a new type of personal dosimeter, the Electronic Personal Dosemeter made by Siemens Plessey Controls Limited. Twenty pre-production dosimeters and a reader were purchased by Ontario Hydro for the assessment. Tests were performed on radiological performance, including reproducibility, accuracy, linearity, detection threshold, energy response, angular response, neutron response, and response time. There were also tests on the effects of a variety of environmental factors, such as temperature, humidity, pulsed magnetic and electric fields, low- and high-frequency electromagnetic fields, light exposure, drop impact, vibration, and splashing. Other characteristics that were tested were alarm volume, clip force, and battery life. The test results were compared with the relevant requirements of three standards: an Ontario Hydro standard for personal alarming dosimeters, an International Electrotechnical Commission draft standard for direct reading personal dose monitors, and an International Electrotechnical Commission standard for thermoluminescence dosimetry systems for personal monitoring. In general, the performance of the Electronic Personal Dosemeter was found to be quite acceptable: it met most of the relevant requirements of the three standards. However, the following deficiencies were found: slow response time; sensitivity to high-frequency electromagnetic fields; poor resistance to dropping; and an alarm that was not loud enough. In addition, the response of the electronic personal dosimeter to low-energy beta rays may be too low for some applications. Problems were experienced with the reliability of operation of the pre-production dosimeters used in these tests. PMID:7790213

  5. Detectors/Dosemeters of galactic and solar cosmic rays.

    PubMed

    Tommasino, L

    2004-01-01

    Different passive multidetector stacks have been developed at the Italian National Agency for Environmental Protection (ANPA-stack), which makes it possible to measure directly ionising radiations, low-energy and high-energy neutrons, and high-energy charged (HZE) particles. The stack consists of several types of passive devices, namely recoil-track and fission-track detectors, bubble detectors, thermoluminescence dosemeters and an electronic personal dosemeter. Most of these detectors have been used on earth for the assessment of the occupational exposure, or in outer space for cosmic ray physics and/or for the assessment of the dose received by astronauts. A great deal of efforts and new developments have been required to make these detectors useful for in-flight measurements. As outcome of these extensive efforts, different new detectors have been developed, which exploit some of the most successful principles of radiation detection, such as the use of avalanche processes to facilitate the registration of nuclear tracks and the use of coincidence-counting to increase the signal-to-noise ratio. On the basis of these new detectors, different systems (generally referred to as ANPA-stack) have been obtained, which have been successfully applied for a variety of different measurements of cosmic ray radiation fields and doses. PMID:15273355

  6. The Role of Historical Operations Information for Supporting Remedial Investigation Work at the Former Harshaw Chemical Site

    SciTech Connect

    Kolhoff, A.; Johnson, R.; Peterson, J.; Picel, K.; DeVaughn, J.

    2008-07-01

    In the early stages of hazardous, toxic, and radioactive waste (HTRW) site investigations, basic record searches are performed to help direct the agencies investigating contaminated sites to areas of concern and to identify contaminants of interest (COI). Plans developed on the basis of this preliminary research alone are often incomplete and result in unexpected discoveries either while in the field investigating the site or after the reports have been written. Many of the sites investigated under the Formerly Utilized Sites Remedial Action Program (FUSRAP) have complex histories that are slowly uncovered over the life of the project. Because of programmatic constraints, nuances of these sites are often discovered late in their programs and result in increased expenditures in order to fully characterize the site, perform a robust feasibility study, and recommend appropriate alternatives for remediation. By identifying resources for public records, classified records, historic aerial photographs, and other sources of site-specific historical information, a process can be established to optimize the collection of information and to develop efficient and complete project plans. In many cases, interviews with past site employees are very useful tools. In combining what is found in the records, observed on historic aerial photographs, and heard from former employees and family members, teams investigating these sites can begin to compile sound and more complete conceptual site models (CSM(s). The former Harshaw Chemical Site (HCS) illustrates this discovery process. HCS is part of FUSRAP. Preliminary investigations by the U.S. Department of Energy (DOE) in the 1970's provided an initial CSM of activities that had taken place that may have resulted in contamination. The remedial investigation (RI) conducted by the U.S. Army Corps of Engineers (USACE) was designed around this CSM. The RI work, however, identified a number of site conditions that were unexpected, including new potential COI associated with recycled uranium and contaminant locations that were inconsistent with the original CSM. As part of an RI Addendum effort, the USACE reconsidered its understanding of HCS historical activities. This effort included an intensive review of available historical aerial photography, an in-depth Potentially Responsible Parties (PRP) investigation, additional analysis of the production processes in place at HCS, and targeted supplemental data collection. The result of this effort was a revised CSM that included a number of previously unidentified potential COI and a much clearer understanding of the processes and resulting waste streams potentially associated with environmental contamination. Because of their complex and often poorly documented operational histories, unexpected discoveries will always be a part of investigating sites such as HCS. Taking advantage of available resources and expending funds for thorough historical research early in the life of a project will help to reduce the chances for expensive field re-mobilizations and significant schedule delays. A complete and accurate site history also allows for more efficient long-term technical and budgetary planning, thus eliminating many obstacles associated with the ultimate disposition of HTRW sites. (authors)

  7. The role of historical operations information for supporting remedial investigation work at the former Harshaw Chemical Site - 8279.

    SciTech Connect

    Johnson, R.; Peterson, J.; Picel, K.; Kolhoff, A.; Devaughn, J.; Environmental Science Division; U. S.Army Corps of Engineers, Buffalo District; Science Applications International Corp.

    2008-01-01

    In the early stages of hazardous, toxic, and radioactive waste (HTRW) site investigations, basic record searches are performed to help direct the agencies investigating contaminated sites to areas of concern and to identify contaminants of interest (COI). Plans developed on the basis of this preliminary research alone are often incomplete and result in unexpected discoveries either while in the field investigating the site or after the reports have been written. Many of the sites investigated under the Formerly Utilized Sites Remedial Action program (FUSRAP) have complex histories that are slowly uncovered over the life of the project. Because of programmatic constraints, nuances of these sites are often discovered late in their programs and result in increased expenditures in order to fully characterize the site, perform a robust feasibility study, and recommend appropriate alternatives for remediation. By identifying resources for public records, classified records, historic aerial photographs, and other sources of site-specific historical information, a process can be established to optimize the collection of information and to develop efficient and complete project plans. In many cases, interviews with past site employees are very useful tools. In combining what is found in the records, observed on historic aerial photographs, and heard from former employees and family members, teams investigating these sites can begin to compile sound and more complete conceptual site models (CSMs). The former Harshaw Chemical Site (HCS) illustrates this discovery process. HCS is part of FUSRAP. Preliminary investigations by the US Department of Energy (DOE) in the 1970s provided an initial CSM of activities that had taken place that may have resulted in contamination. The remedial investigation (RI) conducted by the US Army Corps of Engineers (USACE) was designed around this CSM. The RI work, however, identified a number of site conditions that were unexpected, including new potential COI associated with recycled uranium and contaminant locations that were inconsistent with the original CSM. As part of an RI Addendum effort, the USACE reconsidered its understanding of HCS historical activities. This effort included an intensive review of available historical aerial photography, an in-depth Potentially Responsible Parties (PRP) investigation, additional analysis of the production processes in place at HCS, and targeted supplemental data collection. The result of this effort was a revised CSM that included a number of previously unidentified potential COI and a much clearer understanding of the processes and resulting waste streams potentially associated with environmental contamination. Because of their complex and often poorly documented operational histories, unexpected discoveries will always be a part of investigating sites such as HCS. Taking advantage of available resources and expending funds for thorough historical research early in the life of a project will help to reduce the chances for expensive field remobilizations and significant schedule delays. A complete and accurate site history also allows for more efficient long-term technical and budgetary planning, thus eliminating many obstacles associated with the ultimate disposition of HTRW sites.

  8. Compliance of electronic personal neutron dosemeters with the new International Standard IEC 61526.

    PubMed

    Luszik-Bhadra, M

    2007-01-01

    The recommendations and test requests for the dose equivalent response of personal neutron dosemeters formulated by the new International Standard IEC 61526 are summarised. In particular, IEC 61526 allows the use of broad fields if dosemeters do not fulfil the hard requirements using monoenergetic neutrons. Some broad fields which can work as a replacement field using ISO sources (252Cf, 252Cf (D2O mod.), 241Am-Be) and simulated workplace fields (CANEL and SIGMA) are described. This work shows the results of recent measurements of the personal dose equivalent response for the dosemeters Thermo Electron EPD-N2, Aloka PDM-313 and the prototype dosemeter PTB DOS-2002, and discusses their compliance with respect to the new IEC 61526 standard. PMID:17213218

  9. 1983 ORNL intercomparison of personnel neutron and gamma dosemeters

    SciTech Connect

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

    1985-01-01

    The Ninth Personnel Dosimetry Intercomparison Study was conducted during April 19-21, 1983, at the Oak Ridge National Laboratory. Dosemeters from 33 participating agencies were mounted on water-filled polyethylene elliptical phantoms and exposed to a range of low-level dose equivalents (0.02-0.45 mSv gamma and 0.49-11.14 mSv neutron) which could be encountered during routine personnel monitoring in mixed radiation fields. The Health Physics Research Reactor served as the radiation source for six separate exposures which used four different shield conditions: unshielded and shielded with steel, steel/concrete, and concrete. Results of the neutron measurements indicate that it is not unusual for dose equivalent estimates made under the same conditions by different agencies to differ by more than a factor of 2. Albedo systems, which were the most popular neutron monitors in this study, provided the most accurate results with CR-39 recoil track being least accurate. Track and film neutron systems exhibited problems providing measurable indication of neutron exposure at dose equivalents of about 0.50 mSv. Gamma measurements showed that TLD and film systems generally overestimated dose equivalents in the mixed radiation fields with film exhibiting significant problems providing measurable indication of gamma exposure at dose equivalents lower than about 0.15 mSv. Under the conditions of this study in which exposures were carefully controlled and participants had information concerning exposure conditions and incident spectra prior to dosemeter analysis, only slightly more than half of all neutron and gamma dose equivalent estimates met regulatory accuracy standards relative to reference values. These results indicate that continued improvement of mixed-field personnel dosimetry is required by many participating organizations. 15 references, 30 tables.

  10. A comparison of the response of PADC neutron dosemeters in high-energy neutron fields.

    PubMed

    Trompier, F; Boschung, M; Buffler, A; Domingo, C; Cale, E; Chevallier, M-A; Esposito, A; Ferrarini, M; Geduld, D R; Hager, L; Hohmann, E; Mayer, S; Musso, A; Romero-Esposito, M; Rttger, S; Smit, F D; Sashala Naik, A; Tanner, R; Wissmann, F; Caresana, M

    2014-10-01

    Within the framework of the EURADOS Working Group 11, a comparison of passive neutron dosemeters in high-energy neutron fields was organised in 2011. The aim of the exercise was to evaluate the response of poly-allyl-glycol-carbonate neutron dosemeters from various European dosimetry laboratories to high-energy neutron fields. Irradiations were performed at the iThemba LABS facility in South Africa with neutrons having energies up to 66 and 100 MeV. PMID:24298170

  11. Numerical and experimental results of the operational neutron dosemeter 'Saphydose-N'.

    PubMed

    Lahaye, T; Chau, Q; Mnard, S; Ndontchueng-Moyo, M; Bolognese-Milsztajn, T; Rannou, A

    2004-01-01

    Since 1993, the Institute for Radiological Protection and Nuclear Safety (IRSN) has lead, in association with Electricit de France (EDF), a R&D study of a neutron personal electronic dosemeter. This dosemeter, called 'Saphydose-N', is manufactured by the SAPHYMO company. This paper presents first the optimisation of some detector components using Monte Carlo calculations, and second the test of the manufactured Saphydose-N under radiation following the IEC 1323 standard's recommendations for active personal neutron dosemeters. The measurements with the manufactured dosemeter were performed on the one hand at PTB (Physikalisch-Technische Bundesanstalt) in mono-energetic neutron fields and, on the other hand at IRSN in neutron fields generated by a thermal facility (SIGMA), radionuclide ISO sources and a realistic spectrum (CANEL/T400). The manufactured dosemeter Saphydose-N was also tested during measurement campaigns of the European programme EVIDOS ('Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields') at different nuclear workplaces. The study showed that Saphydose-N complies with the recommendations of standard IEC 1323 and can be used at any workplace with no previous knowledge of the neutron field characteristics. PMID:15353645

  12. Characterization of optically stimulated luminescence dosemeters to measure organ doses in diagnostic radiology

    PubMed Central

    Endo, A; Katoh, T; Kobayashi, I; Joshi, R; Sur, J; Okano, T

    2012-01-01

    Objective The aim of this study was to assess the characteristics of an optically stimulated luminescence dosemeter (OSLD) for use in diagnostic radiology and to apply the OSLD in measuring the organ doses by panoramic radiography. Methods The dose linearity, energy dependency and angular dependency of aluminium oxide-based OSLDs were examined using an X-ray generator to simulate various exposure settings in diagnostic radiology. The organ doses were then measured by inserting the dosemeters into an anthropomorphic phantom while using three panoramic machines. Results The dosemeters demonstrated consistent dose linearity (coefficient of variation<1.5%) and no significant energy dependency (coefficient of variation<1.5%) under the applied exposure conditions. They also exhibited negligible angular dependency (?10%). The organ doses of the X-ray as a result of panoramic imaging by three machines were calculated using the dosemeters. Conclusion OSLDs can be utilized to measure the organ doses in diagnostic radiology. The availability of these dosemeters in strip form proves to be reliably advantageous. PMID:22116136

  13. Characteristics and Performance of the Sunna High Dose Dosemeter Using Green Photoluminescence and UV Absorption Readout Methods

    SciTech Connect

    Miller, Steven D.; Murphy, Mark K.; Tinker, Mike R.; Kovacs, Andres; Mclaughlin, William

    2002-01-01

    Growth in the use of ionizing radiation for medical sterilization and the potential for wide-scale international food irradiation have created the need for robust, mass-producible, inexpensive, and highly accurate radiation dosemeters. The Sunna dosemeter, lithium fluoride injection-moulded in a polyethylene matrix, can be read out using either green photoluminescence or ultraviolet (UV) absorption.

  14. Use of digital dosemeters for supporting staff radiation safety in paediatric interventional radiology suites.

    PubMed

    McNeil, Sarah M; Lai, Priscilla; Connolly, Bairbre L; Gordon, Christopher L

    2013-12-01

    Modern-day interventional radiology (IR) procedures impart a wide range of occupational radiation doses to team members. Unlike thermoluminescent badges, digital dosemeters provide real-time dose readings, making them ideal for identifying different components during IR procedures, which influence staff radiation safety. This study focused solely on paediatric IR (PIR) cases. Digital dosemeters measured the impact of imaging modality, shielding, patient and operator specific factors, on the radiation dose received during various simulated and real live PIR procedures. They recorded potential dose reductions of 10- to 100-fold to each staff member with appropriate use of shielding, choice of imaging method, staff position in the room and complex interplay of other factors. The digital dosemeters were well tolerated by staff. Results highlight some unique radiation safety challenges in PIR that arise from dose increases with magnification use and close proximity of staff to the X-ray beam. PMID:23843426

  15. Developing a method and deriving an uncertainty budget for the internal calibration of dosemeters for radiographic equipment.

    PubMed

    Worrall, M; Sutton, D G

    2015-03-01

    Any institution wishing to perform an internal cross calibration of its diagnostic dosemeters should first quantify the uncertainty associated with this to demonstrate that it remains appropriate for the measurements being undertaken.An uncertainty budget for internal cross calibration that covers a range of locally used dosemeters has been derived using the methodology of the International Atomic Energy Agency. The specific internal cross calibration protocol requirements necessary for this uncertainty budget to be valid are discussed.The final quantified uncertainty is 5.31%; this is dominated by the 5% uncertainty associated with the calibration of the reference instrument. The next largest contributions are from differences in temperature and pressure and dosemeter energy dependence.It has been demonstrated that with careful adherence to a well designed internal cross calibration protocol, dosemeters can be calibrated in-house against a calibrated reference dosemeter with very little increase in the associated calibration uncertainty. PMID:25651390

  16. Validation of a MOSFET dosemeter system for determining the absorbed and effective radiation doses in diagnostic radiology.

    PubMed

    Manninen, A-L; Kotiaho, A; Nikkinen, J; Nieminen, M T

    2015-04-01

    This study aimed to validate a MOSFET dosemeter system for determining absorbed and effective doses (EDs) in the dose and energy range used in diagnostic radiology. Energy dependence, dose linearity and repeatability of the dosemeter were examined. The absorbed doses (ADs) were compared at anterior-posterior projection and the EDs were determined at posterior-anterior, anterior-posterior and lateral projections of thoracic imaging using an anthropomorphic phantom. The radiation exposures were made using digital radiography systems. This study revealed that the MOSFET system with high sensitivity bias supply set-up is sufficiently accurate for AD and ED determination. The dosemeter is recommended to be calibrated for energies <60 and >80 kVp. The entrance skin dose level should be at least 5 mGy to minimise the deviation of the individual dosemeter dose. For ED determination, dosemeters should be implanted perpendicular to the surface of the phantom to prevent the angular dependence error. PMID:25213263

  17. Official dosimetry with personal electronic dosemeters--the framework in Germany.

    PubMed

    Czarwinski, R; Kaulard, J; Pfeffer, W

    2007-01-01

    In Germany, personal electronic dosemeters (AEPDs) are presently applied mainly for operational radiation protection monitoring particularly in nuclear power engineering companies, large hospitals and research centres. This is done in addition to the official dosimetry of record. Therefore, frequently, double monitoring occurs-officially and operationally. A crucial advantage of AEPDs compared with passive dosemeters is the ability to adapt the monitoring period to the working time in controlled areas and to allow an immediate readout of the dose after leaving the controlled area, e.g. a job-related monitoring is possible by correlating the readout dose with the job performed. Germany started a general research project, consisting of two parts, for an optimised implementation of personal electronic dosemeters into official dosimetry. The use of AEPDs as official dosemeters depends on an approval by Federal and Federal State ('Lnder') authorities as an official dosimetry system, which has to comply with special requirements ensuring that the legal requirements are fulfilled. The formulation of these special requirements is in the focus of part one of the research project, supervised by the Federal Office for Radiation Protection (BfS) and performed by the Gesellschaft fr Anlagen- und Reaktorsicherheit (GRS) mbH. As a result of part one, a framework was developed which is the basis for a future technical implementation project. Part one is described in the paper, while part two is still to be initiated and will deal with the implementation and testing phase of the introduction of personal electronic dosemeters as official dosemeters. PMID:16987912

  18. Influence of dosemeter position for the assessment of eye lens dose during interventional cardiology.

    PubMed

    Principi, Sara; Ginjaume, Mercè; Duch, Maria Amor; Sánchez, Roberto M; Fernández, Jose M; Vano, Eliseo

    2015-04-01

    The equivalent dose limit for the eye lens for occupational exposure recommended by the ICRP has been reduced to 20 mSv y(-1) averaged over defined periods of 5 y, with no single year exceeding 50 mSv. The compliance with this new requirement could not be easy in some workplace such as interventional radiology and cardiology. The aim of this study is to evaluate different possible approaches in order to have a good estimate of the eye lens dose during interventional procedures. Measurements were performed with an X-ray system Philips Allura FD-10, using a PMMA phantom to simulate the patient scattered radiation and a Rando phantom to simulate the cardiologist. Thermoluminescence (TL) whole-body and TL eye lens dosemeters together with Philips DoseAware active dosemeters were located on different positions of the Rando phantom to estimate the eye lens dose in typical cardiology procedures. The results show that, for the studied conditions, any of the analysed dosemeter positions are suitable for eye lens dose assessment. However, the centre of the thyroid collar and the left ear position provide a better estimate. Furthermore, in practice, improper use of the ceiling-suspended screen can produce partial protection of some parts of the body, and thus large differences between the measured doses and the actual exposure of the eye could arise if the dosemeter is not situated close to the eye. PMID:25514919

  19. Investigation of a BeO-based optically stimulated luminescence dosemeter.

    PubMed

    Sommer, M; Henniger, J

    2006-01-01

    The optical sensitivity of BeO-based luminophors has been well-known for many years. The optical stimulation of BeO with blue light is most effective. Then the dosemeters emit luminescent light in the ultraviolet-range around 325 nm. Matched on these facts a simple optically stimulated luminescence (OSL) treatment has been developed. Intense blue light-emitting diodes are used for cw-stimulation. A Hamamatsu solar blind photomultiplier detects the OSL-light. Good separation of both spectral ranges by optical filters is very important. The dosemeter has a linear dose response between approximately 20 muGy and >10 Gy. It was suggested, that a modification of stimulation conditions would allow measurements down to 1 muGy. Fading, photon energy dependence and reproducibility of OSL-signal correspond well with requirements to clinical and personal dosemeters. In addition, basic questions of the OSL-process in BeO have been investigated. A relevant point of interest was the dependency of the OSL-signal on stimulation power. PMID:16735572

  20. Determination of the calibration factor of polysulphone film UV dosemeters for terrestrial solar radiation.

    PubMed

    Krins, A; Drschel, B; Knuschke, P; Seidlitz, H K; Thiel, S

    2001-01-01

    Polysulphone film is used as a personal UV dosemeter in dermatological or epidemiological studies. The relative efficiency of this detector does not exactly match the action spectrum as proposed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and to which the UV dose and exposure limits refer. Therefore, the calibration of the dosemeter depends on the spetrum. In the present paper the variation of the calibration factor for terrestrial solar UV spectra is analysed on the basis of a two year observation period at a site near Munich. Germany. A detailed error estimation is included. It is shown that the variation of the calibration factor within this class of spectra is the main contribution to the total uncertainty of the dose determination, which can be up to 40%. The shape of the spectrum of terrestrial solar UV radiation is mainly determined by the total ozone column and the solar elevation angle. It is shown how the calibration depends on these two parameters and how this additional information can help to reduce the measurement error to a residual uncertainty of 17%. Exposure studies of terrestrial solar UV radiation using polysulphone film as a dosemeter would gain in accuracy if total ozone column values at the study's site could be measured or taken from satellite or weather service data. The interpretation of the magnitude of the dose uncertainty depends on the further use of these data. PMID:11707033

  1. Development and characterization of real-time personal neutron dosemeter with two silicon detectors

    NASA Astrophysics Data System (ADS)

    Sasaki, M.; Nakamura, T.; Tsujimura, N.; Ueda, O.; Suzuki, T.

    1998-12-01

    We have developed a new real-time personal neutron dosemeter containing two neutron sensors, a fast and a slow neutron sensor. The former sensor is a p-type silicon semiconductor detector. The slow neutron sensor is also a p-type silicon semiconductor detector and natural boron is doped on the aluminum electrode to produce 10B(n,?) reactions. A thin polyethylene radiator is contacted on the front surface of each sensor to produce recoil protons. The neutron detection efficiencies of these sensors were measured in a thermal neutron field and monoenergetic neutron fields from 8 keV to 22 MeV. By taking the weighted sum of counts given by the two sensors, the detection efficiency could be made to approach to the fluence-to-dose equivalent conversion factor given by ICRP 51. Field tests of the performance of this neutron dosemeter were performed in the radiation environments around several nuclear facilities, including reactor, accelerator, radioisotope and nuclear fuel handling facilities. Based on the results of these field tests, we conclude that our dosemeter is able to provide a reading of the neutron dose equivalent within a factor of 2 margin of accuracy.

  2. Response of dosemeters in the radiation field generated by a TW-class laser system.

    PubMed

    Olovcov, V; Klr, D; Krsa, J; Kr?s, M; Velyhan, A; Zelenka, Z; Rus, B

    2014-10-01

    State-of-the-art laser systems are able to generate ionising radiation of significantly high energies by focusing ultra-short and intense pulses onto targets. Thus, measures ensuring the radiation protection of both working personnel and the general public are required. However, commercially available dosemeters are primarily designed for measurement in continuous fields. Therefore, it is important to explore their response to very short pulses. In this study, the responses of dosemeters in a radiation field generated by iodine high-power and Ti:Sapphire laser systems are examined in proton and electron acceleration experiments. Within these experiments, electron bunches of femtosecond pulse duration and 100-MeV energy and proton bunches with sub-nanosecond pulse duration and energy of several megaelectronvolts were generated in single-shot regimes. Responses of typical detectors (TLD, films and electronic personal dosemeter) were analysed and compared. Further, a first attempt was carried out to characterise the radiation field generated by TW-class laser systems. PMID:24563524

  3. Performance of a personal neutron dosemeter based on direct ion storage at workplace fields in the nuclear industry.

    PubMed

    Boschung, M; Fiechtner, A; Wernli, C

    2007-01-01

    In the framework of the EVIDOS project, funded by the EC, measurements were carried out using dosemeters, based on ionisation chambers with direct ion storage (DIS-N), at several workplace fields, namely, at a fuel processing plant, a boiling and a pressurised water reactor, and near transport and storage casks. The measurements and results obtained with the DIS-N in these workplaces, which are representative for the nuclear industry, are described in this study. Different dosemeter configurations of converter and shielding materials were considered. The results are compared with values for personal dose equivalent which were assessed within the EVIDOS project by other partners. The advantages and limitations of the DIS-N dosemeter are discussed. PMID:17110388

  4. Eye lens monitoring for interventional radiology personnel: dosemeters, calibration and practical aspects of H p (3) monitoring. A 2015 review.

    PubMed

    Carinou, Eleftheria; Ferrari, Paolo; Bjelac, Olivera Ciraj; Gingaume, Merce; Merce, Marta Sans; O'Connor, Una

    2015-09-01

    A thorough literature review about the current situation on the implementation of eye lens monitoring has been performed in order to provide recommendations regarding dosemeter types, calibration procedures and practical aspects of eye lens monitoring for interventional radiology personnel. Most relevant data and recommendations from about 100 papers have been analysed and classified in the following topics: challenges of today in eye lens monitoring; conversion coefficients, phantoms and calibration procedures for eye lens dose evaluation; correction factors and dosemeters for eye lens dose measurements; dosemeter position and influence of protective devices. The major findings of the review can be summarised as follows: the recommended operational quantity for the eye lens monitoring is H p (3). At present, several dosemeters are available for eye lens monitoring and calibration procedures are being developed. However, in practice, very often, alternative methods are used to assess the dose to the eye lens. A summary of correction factors found in the literature for the assessment of the eye lens dose is provided. These factors can give an estimation of the eye lens dose when alternative methods, such as the use of a whole body dosemeter, are used. A wide range of values is found, thus indicating the large uncertainty associated with these simplified methods. Reduction factors from most common protective devices obtained experimentally and using Monte Carlo calculations are presented. The paper concludes that the use of a dosemeter placed at collar level outside the lead apron can provide a useful first estimate of the eye lens exposure. However, for workplaces with estimated annual equivalent dose to the eye lens close to the dose limit, specific eye lens monitoring should be performed. Finally, training of the involved medical staff on the risks of ionising radiation for the eye lens and on the correct use of protective systems is strongly recommended. PMID:26343787

  5. Energy and angular dependence of active-type personal dosemeter for high-energy neutron.

    PubMed

    Rito, Hirotaka; Yamauchi, Tomoya; Oda, Keiji

    2011-07-01

    In order to develop an active-type personal dosemeter having suitable sensitivity to high-energy neutrons, the characteristic response of silicon surface barrier detector has been investigated experimentally and theoretically. An agreement of the shape of pulse-height distribution, its change with radiator thickness and the relative sensitivity was confirmed between the calculated and experimental results for 14.8-MeV neutrons. The angular dependence was estimated for other neutron energies, and found that the angular dependence decreased with the incident energy. The reason was also discussed with regard to the radiator thickness relative to maximum range of recoil protons. PMID:21613268

  6. Measurement models for passive dosemeters in view of uncertainty evaluation using the Monte Carlo method.

    PubMed

    van Dijk, J W E

    2014-12-01

    Two measurement models for passive dosemeters such as thermoluminescent dosemeter, optically stimulated luminescence, radio-photoluminescence, photographic film or track etch are discussed. The first model considers the dose evaluation with the reading equipment as a single measurement, the one-stage model. The second model considers the build-up of a latent signal or latent image in the detector during exposure and the evaluation using a reader system as two separate measurements, the two-stage model. It is discussed that the two-stage model better reflects the cause and effect relations and the course of events in the daily practice of a routine dosimetry service. The one-stage model will be non-linear in crucial input quantities which can give rise to erroneous behavior of the uncertainty evaluation based on the law of propagation of uncertainty. Input quantities that show an asymmetric probability distributions propagate through the one-stage model in a physically not relevant way. PMID:24464818

  7. Photon energy dependence of three fortuitous dosemeters from personal electronic devices, measured by optically stimulated luminescence.

    PubMed

    Beerten, Koen; Vanhavere, Filip

    2010-08-01

    New data are presented with regard to the relative OSL sensitivity of three different emergency dosemeters irradiated to various photon energies approximately between 48 and 1250 keV using blue excitation light. Investigated components extracted from commonly worn objects include those from USB flash drives (alumina substrate), mobile phones (Ba-rich silicate) and credit cards (chip card module). Several basic properties have been investigated such as the overall radiation sensitivity, the shape of the decay curve and fading of the OSL signal. An increase of the sensitivity for low energies relative to (60)Co gamma rays can be observed for the three dosemeters, the increase being very pronounced for the Ba-rich component (factor of 10) and less pronounced for the chip card module (factor of 2). It is concluded that proper dose correction factors for photon energy have to be applied in order to accurately determine the absorbed dose to tissue. The OSL sensitivity to neutron irradiation was investigated as well, but this was found to be less than the gamma sensitivity. PMID:20304766

  8. Development of advanced-type multi-functional electronic personal dosemeter.

    PubMed

    Nunomiya, T; Abe, S; Aoyama, K; Nakamura, T

    2007-01-01

    An advanced-type small, light, multi-functional electronic personal dosemeter has been developed using silicon semiconductor radiation detectors for dose management of workers at nuclear power plants and accelerator facilities. This dosemeter is 62 x 82 x 27 mm(3) in size and approximately 130 g in weight, which is capable of measuring personal gamma ray and neutron dose equivalents, Hp(10), simultaneously. The neutron dose equivalent can be obtained using two types of silicon semiconductors: a slow-neutron sensor (<1 MeV) and a fast-neutron sensor (>1 MeV). The slow neutron sensor is a 10 x 10 mm(2) p-type silicon on which a natural boron layer is deposited around an aluminium electrode. The fast neutron sensor is also a 10 x 10 mm(2) p-type silicon crystal on which an amorphous silicon hydride is deposited. The neutron energy response corresponding to the fluence-to-dose-equivalent conversion coefficient given by ICRP Publication 74 has been evaluated using a monoenergetic neutron source from 250 keV to 15 MeV at the Fast Neutron Laboratory of Tohoku University. As the result, the Hp(10) response to neutrons in the energy range of 250 keV and 4.4 MeV within +/-50% difference has been obtained. PMID:17704353

  9. Efficiency of a radiophotoluminescence glass dosemeter for low-earth-orbit space radiation

    NASA Technical Reports Server (NTRS)

    Yasuda, H.; Fujitaka, K.; Badhwar, G. D. (Principal Investigator)

    2002-01-01

    Chips of a radiophotoluminescence glass dosemeter (RPLG) were used for measurements of space radiation during a 9.8 d Shuttle-Mir mission (STS-91) at an altitude of 400 km and an inclination of 51.65 degrees. Two of RPLG chips were put into each of 59 positions in or on a life-size human phantom. The RPLG values equivalent to 137Cs gamma ray absorbed doses were found to be systematically lower than those of a Mg2SiO4:Tb thermoluminescence dosemeter (TDMS). In comparison with the organ or tissue absorbed dose and dose equivalent values that were estimated using a combination of TDMS and plastic nuclear track detectors, the efficiencies of the RPLG chips were about 80% for the water absorbed dose and about 40% for the dose equivalent. Whereas the percentage values will change during different missions, such additional information obtained from small RPLG chips is useful for improving the reliability of radiation dosimetry in space.

  10. Performance of the EPD-N2 dosemeter for monitoring aircrew doses.

    PubMed

    Scherpelz, R I; Cezeaux, J R

    2015-03-01

    United States Air Force (USAF) aircrew fly at altitudes and for durations where doses from cosmic radiation are significant enough to warrant monitoring. This study evaluated a candidate radiological monitoring system for USAF aircrew, the Thermo Scientific electronic personnel dosemeter (EPD-N2). The evaluation consisted of characterising the device in a well-characterised radiation field at a European Organization for Nuclear Research (CERN) accelerator, and aboard an USAF aircraft. The performance of the EPDs was evaluated by comparison with accepted values for dose at the CERN facility, comparison with the value calculated by flight dose software and comparison with the value estimated by a tissue-equivalent proportional counter aboard the aircraft. This study recommends that a correction factor of 1/CF = 1/3.9 be applied to EPD-N2 measurements aboard aircraft flights. The uncertainty in this correction factor is 11.8 %. PMID:25108394

  11. Two-dimensional differential calibration method for a neutron dosemeter using a thermal neutron beam.

    PubMed

    Matsumoto, Tetsuro; Harano, Hideki; Masuda, Akihiko; Nishiyama, Jun; Matsue, Hideaki; Uritani, Akira; Nunomiya, Tomoya

    2013-08-01

    A new thermal neutron calibration method to experimentally determine the energy response function of a neutron detector using a pulse parallel beam and the time-of-flight (TOF) technique is developed. The calibration method was experimentally demonstrated for a (3)He proportional counter and an electric personal dosemeter using a pulsed thermal neutron beam from the research reactor JRR-3M. The responses of the detectors were successfully obtained as a function of neutron energy. However, detailed information on the detector structure is required to obtain the spatial response distribution for the detector. The authors further propose an improved calibration method obtaining the spatial response distribution using a pulsed narrow beam, the TOF technique and a beam scanning technique. PMID:23509397

  12. Photon beam audits for radiation therapy clinics: a pilot mailed dosemeter study in Turkey.

    PubMed

    Yegingil, Z; DeWerd, L A; Davis, S D; Hammer, C; Kunugi, K

    2012-01-01

    A thermoluminescent dosemeter (TLD) mailed dose audit programme was performed at five radiotherapy clinics in Turkey. The intercomparison was organised by the University of Wisconsin Radiation Calibration Laboratory (UWRCL), which was responsible for the technical aspects of the study including reference irradiations, distribution, collection and evaluation. The purpose of these audits was to perform an independent dosimetry check of the radiation beams using TLDs sent by mail. Acrylic holders, each with five TLD chips inside and instructions for their irradiation to specified absorbed dose to water of 2 Gy, were mailed to all participating clinics. TLD irradiations were performed with a 6 MV linear accelerator and (60)Co photon beams. The deviations from the TL readings of UWRCL were calculated. Discrepancies inside the limits of 5 % between the participant-stated dose, and the TLD-measured dose were considered acceptable. One out of 10 beams checked was outside this limit, with a difference of 5.8 %. PMID:21362695

  13. Automation of radiation dosimetry using PTW dosemeter and LabVIEW

    NASA Astrophysics Data System (ADS)

    Weiss, C.; Al-Frouh, K.; Anjak, O.

    2011-10-01

    Automation of UNIDOS "Dosemeter" using personal computer (PC) is discussed in this paper. In order to save time and eliminate human operation errors during the radiation dosimetry, suitable software, using LabVIEW graphical programming language, was written to automate and facilitate the processes of measurements, analysis and data storage. The software calculates the calibration factor of the ionization chamber in terms of air kerma or absorbed dose to water according to IAEA dosimetry protocols. It also has the ability to print a calibration certificate. The obtained results using this software are found to be more reliable and flexible than those obtained by manual methods previously employed. Using LabVIEW as a development tool is extremely convenient to make things easier when software modifications and improvements are needed.

  14. Dose measurements for gamma knife with radiophotoluminescent glass dosemeter and radiochromic film.

    PubMed

    Hsu, Shih-Ming; Lee, Jeng-Hung; Hsu, Fang-Yuh; Lee, Hsiu-Wen; Hung, Shih-Kai; Liao, Yi-Jen; Lee, Moon-Sing

    2011-07-01

    Stereotactic radiosurgery (SRS) is designed for patients with small lesion areas that are not suitable for actual surgery. SRS delivers high dose to the lesion with high gradient on the irradiation margin area. In this study, radiophotoluminescent glass dosemeter (RPLGD) and radiochromic film were used to measure the output factor of a gamma knife. Also, a Monte Carlo code (OMEGA/BEAM) was applied to simulate the output factor. For 14 and 8 mm sizes of helmet collimators, the variations of output factors determined with RPLGD, radiochromic film, the Monte Carlo code and Elekta were all within 0.5 %. When helmet collimator size was 4 mm, the output factors detected from RPLGD, radiochromic film and Monte Carlo simulation were all within 3.2 % when compared with Elekta. Taken together, RPLGD, radiochromic film and Monte Carlo simulation will be used as precise tools to measure the output factor of a gamma knife. PMID:21493605

  15. Study of a selection of 10 historical types of dosemeter: variation of the response to Hp(10) with photon energy and geometry of exposure.

    PubMed

    Thierry-Chef, I; Pernicka, F; Marshall, M; Cardis, E; Andreo, P

    2002-01-01

    An international collaborative study of cancer risk among workers in the nuclear industry is tinder way to estimate direetly the cancer risk following protracted low-dose exposure to ionising radiation. An essential aspect of this study is the characterisation and quantification of errors in available dose estimates. One major source of errors is dosemeter response in workplace exposure conditions. Little information is available on energy and geometry response for most of the 124 different dosemeters used historically in participating facilities. Experiments were therefore set up to assess this. using 10 dosemeter types representative of those used over time. Results show that the largest errors were associated with the response of early dosemeters to low-energy photon radiation. Good response was found with modern dosemeters. even at low energy. These results are being used to estimate errors in the response for each dosemeter type, used in the participating facilities, so that these can be taken into account in the estimates of cancer risk. PMID:12408486

  16. Calibration of an eye lens dosemeter in terms of Hp(3) to be used in interventional radiology

    NASA Astrophysics Data System (ADS)

    Borges, F. L. S.; Guimarães, M. C.; Da Silva, T. A.; Nogueira Tavares, M. S.

    2014-11-01

    Recently, the International Commission on Radiological Protection has reviewed epidemiological evidences suggesting that there were tissue reaction effects in the eye lens below the previously considered absorbed dose threshold. A new statement related to the eye lens was issued that changed the absorbed dose threshold and reduced the dose limits for occupationally exposed persons. As consequence, some planned exposures require eye lens dosimetry and a debate was raised on the adequacy of the dosimetric quantity and on its method of measurement. The aim of this work was to study the methodology for calibrating the EYE-DTM holder with a TLD-100H Harshaw chip detector and to determine its angular and energy dependences in terms of personal dose equivalent, Hp(3).

  17. Effective dose assessment in the maxillofacial region using thermoluminescent (TLD) and metal oxide semiconductor field-effect transistor (MOSFET) dosemeters: a comparative study

    PubMed Central

    Schulze, D; Wolff, J; Rottke, D

    2014-01-01

    Objectives: The objective of this study was to compare the performance of metal oxide semiconductor field-effect transistor (MOSFET) technology dosemeters with thermoluminescent dosemeters (TLDs) (TLD 100; Thermo Fisher Scientific, Waltham, MA) in the maxillofacial area. Methods: Organ and effective dose measurements were performed using 40 TLD and 20 MOSFET dosemeters that were alternately placed in 20 different locations in 1 anthropomorphic RANDO head phantom (the Phantom Laboratory, Salem, NY). The phantom was exposed to four different CBCT default maxillofacial protocols using small (4??5?cm) to full face (20??17?cm) fields of view (FOVs). Results: The TLD effective doses ranged between 7.0 and 158.0?Sv and the MOSFET doses between 6.1 and 175.0?Sv. The MOSFET and TLD effective doses acquired using four different (FOV) protocols were as follows: face maxillofacial (FOV 20??17?cm) (MOSFET, 83.4?Sv; TLD, 87.6?Sv; ?5%); teeth, upper jaw (FOV, 8.5??5.0?cm) (MOSFET, 6.1?Sv; TLD, 7.0?Sv; ?14%); tooth, mandible and left molar (FOV, 4??5?cm) (MOSFET, 10.3?Sv; TLD, 12.3?Sv; ?16%) and teeth, both jaws (FOV, 10??10?cm) (MOSFET, 175?Sv; TLD, 158?Sv; +11%). The largest variation in organ and effective dose was recorded in the small FOV protocols. Conclusions: Taking into account the uncertainties of both measurement methods and the results of the statistical analysis, the effective doses acquired using MOSFET dosemeters were found to be in good agreement with those obtained using TLD dosemeters. The MOSFET dosemeters constitute a feasible alternative for TLDs for the effective dose assessment of CBCT devices in the maxillofacial region. PMID:25143020

  18. Relative response of alanine dosemeters for high-energy electrons determined using a Fricke primary standard

    NASA Astrophysics Data System (ADS)

    Vrs, Sndor; Anton, Mathias; Boillat, Bndicte

    2012-03-01

    A significant proportion of cancer patients is treated using MeV electron radiation. One of the measurement methods which is likely to furnish reliable dose values also under non-reference conditions is the dosimetry using alanine and read-out via electron spin resonance (ESR). The system has already proven to be suitable for QA purposes for modern radiotherapy involving megavoltage x-rays. In order to render the secondary standard measurement system of the Physikalisch-Technische Bundesanstalt based on alanine/ESR useable for dosimetry in radiotherapy, the dose-to-water (DW) response of the dosemeter needs to be known for relevant radiation qualities. For MeV electrons, the DW response was determined using the Fricke primary standard of the Swiss Federal Office of Metrology. Since there were no citable detailed publications on the Swiss primary standard available, this measurement system is described in some detail. The experimental results for the DW response are compared to results of Monte Carlo simulations which model in detail the beams furnished by the electron accelerator as well as the geometry of the detectors. The agreement between experiment and simulation is very good, as well as the agreement with results published by the National Research Council of Canada which are based on a different primary standard. No significant dependence of the DW response was found in the range between 6 and 20?MeV. It is therefore suggested to use a unique correction factor kE for alanine for all MeV qualities of kE = 1.012 0.010.

  19. Evaluation of a personal and environmental dosemeter based on CR-39 track detectors in quasi-monoenergetic neutron fields.

    PubMed

    Caresana, M; Ferrarini, M; Parravicini, A; Sashala Naik, A

    2014-10-01

    In this paper, the evaluation of the dosimetric capability of a detector based on a CR-39 solid-state nuclear track detector coupled to a 1 cm thickness of PMMA radiator was made with the aim of understanding the applicability of this technique to personal and environmental neutron dosimetry. The dosemeter has been exposed to monoenergetic and quasi-monoenergetic neutron beams at PTB in Braunschweig, Germany and at Ithemba Laboratories, in Faure, South Africa, with peak energies ranging from 0.565 to 100 MeV. The results showed a response that is almost independent of the neutron energy in the whole energy range. PMID:24324248

  20. Bias and uncertainty of penetrating photon dose measured by film dosemeters in an epidemiological study of US nuclear workers.

    PubMed

    Daniels, R D; Schubauer-Berigan, M K

    2005-01-01

    A retrospective exposure assessment of 1269 study subjects was completed for use in a multi-site case-control study of the relationship between protracted workplace external radiation exposure and leukaemia mortality. The majority of exposure data result from film badge monitoring programmes at the four US weapons production facilities and a US Naval shipyard. Bias and uncertainty in reported exposures among study facilities and across time were as result of differences in incident photon energy, exposure geometry, dosemeter type and dosimetry methods. These sources of measurement uncertainty were examined by facility and time to derive bias factors (B) for normalising exposures. In conjunction with facility reported results, the bias factors provide a means to estimate the equivalent dose, penetrating to a depth of 10 mm [H(p)(10)] and the equivalent dose to the active bone marrow for use in the epidemiological study. Uncertainty was expressed as the constructed 95% confidence interval (i.e. the 2.5th-97.5th% range) of the estimated parameter. The bias factors indicate that recorded exposures provide a reasonable estimate of H(p)(10) (bias factor near unity) and overestimate equivalent dose to active bone marrow (H(T)) by a factor between 1.2 and 1.7. On average, dosemeter-response uncertainties estimated using Monte Carlo simulation were approximately +/-19 and +/-33% for H(p)(10) and H(T), respectively. PMID:15769802

  1. Effects of high ambient temperature on glow-peak fading properties of LiF:Mg,Ti thermoluminescent dosemeters.

    PubMed

    Harvey, John A; Kearfott, Kimberlee J

    2012-04-01

    The effects of a controlled high temperature environment on LiF:Mg,Ti thermoluminescent dosemeters (TLDs) were investigated. TLDs were exposed to ambient temperatures of 30, 40 and 50°C. Sensitivity changes before irradiation, typically called pre-irradiation fading, and signal loss after irradiation, called post-irradiation fading, were studied. Dosemeters were subjected to up to 33 d of pre-irradiation and 68 d of post-irradiation storage. For pre-irradiation fading, peak 5 showed a signal increase of ∼30 % and peak 4 showed an ∼30 % decrease in 20 d. The sum of the areas of peaks 4 and 5 remained relatively constant even for long pre-irradiation times, although at 50°C, losses in peak 5 signal were too significant to maintain the sum of peaks 4 and 5 constant. Peak 3 was still detectable even at 50°C and the longest irradiation times, but peak 2 was very difficult to detect after 15-20 d, especially with post-irradiation fading. PMID:21733861

  2. Characterising Passive Dosemeters for Dosimetry of Biological Experiments in Space (dobies)

    NASA Astrophysics Data System (ADS)

    Vanhavere, Filip; Spurny, Frantisek; Yukihara, Eduardo; Genicot, Jean-Louis

    Introduction: The DOBIES (Dosimetry of biological experi-ments in space) project focusses on the use of a stan-dard dosimetric method (as a combination of differ-ent passive techniques) to measure accurately the absorbed doses and equivalent doses in biological samples. Dose measurements on biological samples are of high interest in the fields of radiobiology and exobiology. Radiation doses absorbed by biological samples must be quantified to be able to determine the relationship between observed biological effects and the radiation dose. The radiation field in space is very complex, con-sisting of protons, neutrons, electrons and high-energy heavy charged particles. It is not straightfor-ward to measure doses in this radiation field, cer-tainly not with only small and light passive doseme-ters. The properties of the passive detectors must be tested in radiation fields that are representative of the space radiation. We will report on the characterisation of different type of passive detectors at high energy fields. The results from such characterisation measurements will be applied to recent exposures of detectors on the International Space Station. Material and methods: Following passive detectors are used: thermoluminescent detectors (TLD) optically stimulated luminescence detectors (OSLD) track etch detectors (TED) The different groups have participated in the past to the ICCHIBAN series of irradiations. Here protons and other particles of high energy were used to de-termine the LET-dependency of the passive detec-tors. The last few months, new irradiations have been done at the iThemba labs (100-200 MeV protons), Dubna (145 MeV protons) and the JRC-IRMM (quasi mono energetic neutrons up to 19 MeV). All these detectors were also exposed to a simulated space radiation field at CERN (CERF-field). Discussion: The interpretation of the TLD and OSLD results is done using the measured LET spectrum (TED) and the LET-dependency curves of ths TLD and OSLDs. These LET- dependency curves are determined based on the different irradiations listed above. We will report on the results of the different detectors in these fields. Further information on the LET of the space irradia-tion can be deduced from the ratio of the different peaks of the TLDs after glow curve deconvolution, and from the shape of the decay curve of the OSLDs. The results in the CERF field can on the other hand directly being used as a calibration for space radia-tion fields. Conclusion: Combining different passive detectors will lead to improved information on the radiation field, and thus to a better estimation of the absorbed dose to the bio-logical samples. We use the characterisations on high energy accelerators to improve the estimation of some recent space doses.

  3. Performance of the electronic personal dosemeter for neutron 'Saphydose-N' at different workplaces of nuclear facilities.

    PubMed

    Lahaye, T; Chau, Q; Mnard, S; Lacoste, V; Muller, H; Luszik-Bhadra, M; Reginatto, M; Bruguier, P

    2006-01-01

    This paper mainly aims at presenting the measurements and the results obtained with the electronic personal neutron dosemeter Saphydose-N at different facilities. Three campaigns were led in the frame of the European contract EVIDOS ('Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields'). The first one consisted in the measurements at the IRSN French research laboratory in reference neutron fields generated by a thermal facility (SIGMA), radionuclide ISO sources ((241)AmBe; (252)Cf; (252)Cf(D(2)O)\\Cd) and a realistic spectrum (CANEL/T400). The second one was performed at the Krmmel Nuclear Power Plant (Germany) close to the boiling water reactor and to a spent fuel transport cask. The third one was realised at Mol (Belgium), at the VENUS Research Reactor and at Belgonuclaire, a fuel processing factory. PMID:16820401

  4. Energy response of a two-dimensional sheet-type LiF:Mg,Cu,P TL dosemeter to photons.

    PubMed

    Konnai, Akiko; Nariyama, Nobuteru; Ohnishi, Seiki; Odano, Naoteru; Ozasa, Naoto; Ishikawa, Yuhzoh

    2006-01-01

    A 2-D tissue-equivalent sheet-type dosemeter (NTL sheet) was developed using thermoluminescent material of LiF:Mg,Cu,P (NTL-250). The energy responses of the NTL sheet and NTL-250 powder were measured with 10-150 keV monoenergetic photons from synchrotron radiation at SPring-8. The sample was irradiated by a rotational method for the uniform irradiation with the narrow beam. Linearity of the NTL-250 was confirmed up to 2 Gy. Energy responses of the NTL sheet and NTL-250 powder were close to that of soft tissue. On the other hand, the BaSO(4) sheet, which has been used practically, showed the response that the sensitivity approximately 60 keV was 100 times higher than that for (60)Co gamma rays. Therefore the NTL sheet can be said to have excellent properties for dose measurements. PMID:16614093

  5. A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources.

    PubMed

    Sliski, Alan; Soares, Christopher; Mitch, Michael G

    2006-01-01

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a (103)Pd source of air-kerma strength 3.4 U (1 U = 1 microGy m(2) h(-1)), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries such as eye applicators for treating macular degeneration. PMID:16782747

  6. Measurements of non-target organ doses using MOSFET dosemeters for selected IMRT and 3D CRT radiation treatment procedures.

    PubMed

    Wang, Brian; Xu, X George

    2008-01-01

    Many expressed concerns about the potential increase in second cancer risk from the widespread shift to intensity-modulated radiation therapy (IMRT) techniques from traditional 3-D conformal radiation treatment (3D CRT). This paper describes the study on in-phantom measurements of radiation doses in organ sites away from the primary tumour target. The measurements involved a RANDO((R)) phantom and Metal Oxide Semiconductor Field Effect Transistor dosemeters for selected 3D CRT and IMRT treatment plans. Three different treatment plans, 4-field 3D CRT, 6-field 3D CRT and 7-field IMRT for the prostate, were considered in this study. Steps to reconstruct organ doses from directly measured data were also presented. The dosemeter readings showed that the doses decrease as the distances increase for all treatment plans. At 40 cm from the prostate target, doses were <1% of the therapeutic dose. At this location, however, the IMRT plan resulted in an absorbed dose from photons, that is a factor of 3-5 higher than the 3D CRT treatment plans. This increase on absorbed dose is due to the increased exposure time for delivering the IMRT plan. The total monitor unit (MU) was 2850 for the IMRT case, while the MU was 1308 and 1260 for 6-field and 4-field 3D CRT cases, respectively. Findings from this case study involving the prostate treatments agree with those from previous studies that IMRT indeed delivers higher photon doses to locations that are away from the primary target. PMID:17627959

  7. Effect of short-term sensitivity loss in LiF:Mg,Cu,P thermoluminescent dosemeter and its implications on personnel dosimetry operations.

    PubMed

    Romanyukha, Alexander; Delzer, Jeffrey A; Grypp, Matthew D; Williams, Anthony S

    2016-02-01

    A short-term sensitivity loss in LiF:Mg,Cu,P thermoluminescent dosemeters (TLDs) was observed and is described. Its observation occurred during a pre-irradiation anneal with a slightly elevated maximum temperature (5-15C), which causes notable under-response (5-10 %) of the subsequent read at the recommended time-temperature profile (TTP), which has a peak temperature of 260C. A subsequent irradiation and reading using the recommended TTP showed partial or complete recovery of the TLD's sensitivity. To the best of our knowledge, there were no publications on possible implications of a one-time 5-15C overheat of LiF:Mg,Cu,P TLDs during anneal. This is not unusual when several readers with some variations in their heating cycles are used to calibrate and process the same population of dosemeters. A special test to identify if a small uncontrolled overheating of a dosemeter element has occurred was developed and tested. Two practical implications of the effect of a short-term sensitivity loss in LiF:Mg,Cu,P, e.g. inconsistency in results of metrological traceability verification and reporting of false neutron doses, are described in detail. Simple indicators of a small uncontrolled overheating are provided. PMID:25767182

  8. Energy response of GR-200A thermoluminescence dosemeters to 60Co and to monoenergetic synchrotron radiation in the energy range 28-40 keV.

    PubMed

    Emiro, F; Di Lillo, F; Mettivier, G; Fedon, C; Longo, R; Tromba, G; Russo, P

    2016-01-01

    The response of LiF:Mg,Cu,P thermoluminescence dosemeters (type GR-200A) to monoenergetic radiation of energy 28, 35, 38 and 40 keV was evaluated with respect to irradiation with a calibrated (60)Co gamma-ray source. High-precision measurements of the relative air kerma response performed at the SYRMEP beamline of the ELETTRA synchrotron radiation facility (Trieste, Italy) showed a significant deviation of the average response to low-energy X-rays from that to (60)Co, with an over-response from 6 % (at 28 keV) to 22 % (at 40 keV). These data are not consistent with literature data for these dosemeters, where model predictions gave deviation from unity of the relative air kerma response of about 10 %. The authors conclude for the need of additional determinations of the low-energy relative response of GR-200A dosemeters, covering a wider range of monoenergetic energies sampled at a fine energy step, as planned in future experiments by their group at the ELETTRA facility. PMID:25737582

  9. Assessment of effective radiation dose of an extremity CBCT, MSCT and conventional X ray for knee area using MOSFET dosemeters.

    PubMed

    Koivisto, Juha; Kiljunen, Timo; Wolff, Jan; Kortesniemi, Mika

    2013-12-01

    The objective of this study was to assess and compare the organ and effective doses in the knee area resulting from different commercially available multislice computed tomography devices (MSCT), one cone beam computed tomography device (CBCT) and one conventional X-ray radiography device using MOSFET dosemeters and an anthropomorphic RANDO knee phantom. Measurements of the MSCT devices resulted in effective doses ranging between 27 and 48 Sv. The CBCT measurements resulted in an effective dose of 12.6 Sv. The effective doses attained using the conventional radiography device were 1.8 Sv for lateral and 1.2 Sv for anterior-posterior projections. The effective dose resulting from conventional radiography was considerably lower than those recorded for the CBCT and MSCT devices. The MSCT effective dose results were two to four times higher than those measured on the CBCT device. This study demonstrates that CBCT can be regarded as a potential low-dose 3D imaging technique for knee examinations. PMID:23825221

  10. Numerical simulations for diamond sensors as real-time X-ray skin dosemeters; comparison to silicon

    NASA Astrophysics Data System (ADS)

    Jung, M.; Morel, J.; Siffert, P.

    2008-03-01

    Simulation results from Monte Carlo codes developed in our laboratory are used to analyze and improve detector responses against unknown high flux X-ray spectra exposures, as encountered in medicine. The algorithms are applied to diamond and silicon based dosemeters studies. The simulations are focused on real-time skin dosimetry for X-ray energies between 10 and 200 keV. The detector response is simulated as an induced collected charge under high fluence irradiation, to control patient injury. The dose equivalent response at 0.07 mm skin depth is calculated for a large set of diamond sensors. Their sensitivity, accuracy and angular response dispersion are presented. The quasi-tissue equivalent property of the diamond material allows maximum response uncertainties lower than 10% at least up to 75? opening incidences. For such monitors the amount of collected charges shows an asymptotic maximum limit near 80 nC Sv-1 per mm 3 sensor interaction volume. These performances are discussed, and compared to those of silicon diodes.

  11. On the use of LiF:Mg,Ti thermoluminescence dosemeters in space--a critical review.

    PubMed

    Horowitz, Y S; Satinger, D; Fuks, E; Oster, L; Podpalov, L

    2003-01-01

    The use of LiF:Mg,Ti thermoluminescence dosemeters (TLDs) in space radiation fields is reviewed. It is demonstrated in the context of modified track structure theory and microdosimetric track structure theory that there is no unique correlation between the relative thermoluminescence (TL) efficiency of heavy charged particles, neutrons of all energies and linear energy transfer (LET). Many experimental measurements dating back more than two decades also demonstrate the multivalued, non-universal, relationship between relative TL efficiency and LET. It is further demonstrated that the relative intensities of the dosimetric peaks and especially the high-temperature structure are dependent on a large number of variables, some controllable, some not. It is concluded that TL techniques employing the concept of LET (e.g. measurement of total dose, the high-temperature ratio (HTR) methods and other combinations of the relative TL efficiency of the various peaks used to estimate average Q or simulate Q-LET relationships) should be regarded as lacking a sound theoretical basis, highly prone to error and, as well, lack of reproducibility/universality due to the absence of a standardised experimental protocol essential to reliable experimental methodology. PMID:14653322

  12. Advantage of 3D volumetric dosemeter in delivery quality assurance of dynamic arc therapy: comparison of pencil beam and Monte Carlo calculations

    PubMed Central

    Shin, H-J; Song, J H; Jung, J-Y; Kwak, Y-K; Kay, C S; Kang, Y-N; Choi, B O; Jang, H S

    2013-01-01

    Objective: To evaluate the accuracy of pencil beam calculation (PBC) and Monte Carlo calculation (MCC) for dynamic arc therapy (DAT) in a cylindrically shaped homogenous phantom, by comparing the two plans with an ion chamber, a film and a three-dimensional (3D) volumetric dosemeter. Methods: For this study, an in-house phantom was constructed, and the PBC and MCC plans for DAT were performed using iPlan RT (BrainLAB, Heimstetten, Germany). The A16 micro ion chamber (Standard Imaging, Middleton, WI), Gafchromic EBT2 film (International Specialty Products, Wayne, NJ) and ArcCHECK (Sun Nuclear, Melbourne, FL) were used for measurements. For comparison with each plan, two-dimensional (2D) and 3D gamma analyses were performed using 3%/3?mm and 2%/2?mm criteria. Results: The difference between the PBC and MCC plans using 2D and 3D gamma analyses was found to be 7.85% and 28.8%, respectively. The ion chamber and 2D dose distribution measurements did not exhibit this difference revealed by the comparison between the PBC and MCC plans. However, the 3D assessment showed a significant difference between the PBC and MCC (62.7% for PBC vs 93.4% for MCC, p?=?0.034). Conclusion: Evaluation using a 3D volumetric dosemeter can be clinically useful for delivery quality assurance (QA), and the MCC should be used to achieve the most reliable dose calculation for DAT. Advances in knowledge: (1) The DAT plan calculated using the PBC has a limitation in the calculation methods, and a 3D volumetric dosemeter was found to be an adequate tool for delivery QA of DAT. (2) The MCC was superior to PBC in terms of the accuracy in dose calculation for DAT even in the homogenous condition. PMID:24234583

  13. Technical performance of the Luxel Al(2)O(3):C optically stimulated luminescence dosemeter element at radiation oncology and nuclear accident dose levels.

    PubMed

    Miller, Steven D; Murphy, Mark K

    2007-01-01

    The dose ranges typical for radiation oncology and nuclear accident dosimetry are on the order of 2-70 Gy and 0.1-5 Gy, respectively. In terms of solid-state passive dosimetry, thermoluminescent (TL) materials historically have been used extensively for these two applications, with silver-halide, leuco-dye and BaFBr:Eu-based films being used on a more limited basis than TL for radiation oncology. This present work provides results on the performance of a film based on an aluminum oxide, Al(2)O(3):C, for these dosimetry applications, using the optically stimulated luminescence (OSL) readout method. There have been few investigations of Al(2)O(3):C performance at radiation oncology and nuclear accident dose levels, and these have included minimal dosimetric and environmental effects information. Based on investigations already published, the authors of this present study determined that overall improvements over film and TLDs for this Al(2)O(3):C OSL technology at radiation oncology and nuclear accident dose levels may include (1) a more tissue-equivalent response to photons compared to X-ray film, (2) higher sensitivity, (3) ability to reread dosemeters and (4) diagnostic capability using small-area imaging. The results of the present investigation indicate that additional favourable performance characteristics for the Al(2)O(3):C dosemeter are a wide dynamic range (0.001-100 Gy), a response insensitive to temperature and moisture over a wide range, negligible dose rate dependence, and minimal change in post-irradiation response. As a radiation detection medium, this OSL phosphor offers an assortment of dosimetry properties that will permit it to compete with current radiation detection technologies such as silver-halide, leuco-dye and photostimulable-phosphor-based films, as well as TLDs. PMID:17164274

  14. Technical Performance of the Luxel Al2O3:C Optically Stimulated Luminescence Dosemeter Element at Radiation Oncology and Nuclear Accident Dose Levels

    SciTech Connect

    Miller, Steven D.; Murphy, Mark K.

    2006-12-12

    The dose ranges typical for radiation oncology and nuclear accident dosimetry are on the order of 2?70 Gy and 0.1?5 Gy, respectively. In terms of solid-state passive dosimetry; thermoluminescent (TL) materials historically have been used extensively for these two applications, with silver-halide, leuco-dye, and BaFBr:Eu-based films being used on a more limited basis than TL for radiation oncology. This present work provides results on the performance of a film based on an aluminum oxide, Al2O3:C, for these dosimetry applications, using the optically-stimulated luminescence (OSL) readout method. There have been few investigations of Al2O3:C performance at radiation oncology and nuclear accident dose levels, and these have included minimal dosimetric and environmental effects information. Based on investigations already published, the authors of this present study determined that overall improvements over film and TLDs for this Al2O3:C OSL technology at radiation oncology and nuclear accident dose levels may include (1) a more tissue-equivalent response to photons compared to X-ray film, (2) higher sensitivity, (3) ability to reread dosemeters, and (4) diagnostic capability using small-area imaging. The results of the present investigation indicate that additional favorable performance characteristics for the Al2O3:C dosemeter are a wide dynamic range(0.001 to 100 Gy), a response insensitive to temperature and moisture over a wide range, negligible dose rate dependence, and minimal change in post-irradiation response. As a radiation detection medium, this OSL phosphor offers an assortment of dosimetry properties that will permit it to compete with current radiation detection technologies such as silver-halide, leuco-dye, and photostimulable-phosphor based films, as well as TLDs.

  15. Characteristics of a 85Kr beta-particle source applied in Series 1 reference irradiations of DIS-1 direct ion storage dosemeters.

    PubMed

    Hakanen, A T; Sipilä, P M; Sahla, T T

    2007-01-01

    Characteristics necessary to specify an ISO 6980 Series 1 reference radiation field were determined for a commercially available 85Kr beta-particle source, using a BEAM EGS4 Monte Carlo code. The characteristics include residual maximum beta energy, E(res), and the uniformity of the dose rate over the calibration area. The E(res) and the uniformity were also determined experimentally, using an extrapolation ionization chamber (EC) and a 0.2 cm3 parallel plate ionization chamber, respectively. The depth-dose curve measured with the EC gave a value 0.62 MeV for the E(res). Series 2 90Sr + 90Y and Series 1(85) Kr beta-particle sources calibrated for H(p)(0.07) at the secondary standard dosimetry laboratory (SSDL) of STUK were used to determine the energy and angular responses of DIS-1 direct ion storage dosemeters. The averaged zero angle H(p)(0.07) responses to the 90Sr + 90Y and 85Kr reference radiations were 135 and 80%, respectively. The responses were normalized to 100%, H(p)(0.07) response to 137Cs photon radiation. PMID:17548464

  16. The response of lif thermoluminescence dosemeters to photon beams in the energy range from 30 kV x rays to 60Co gamma rays.

    PubMed

    Davis, S D; Ross, C K; Mobit, P N; Van der Zwan, L; Chase, W J; Shortt, K R

    2003-01-01

    The energy response of standard (TLD-100) and high-sensitivity (TLD-100H) LiF thermoluminescence dosemeters (TLDs) has been studied for photon beams with mean energies from about 25 keV to 1100 keV. Canadian primary standards for air kerma were used to establish the air kerma rates for each of the photon beams. TLDs were mounted in a PMMA holder and the air kerma response was measured as a function of energy. The EGSnrc Monte Carlo code was used to model the TLD holder and calculate the absorbed dose to the TLD chip per unit air kerma for each beam. The measured and calculated results were combined to obtain the intrinsic dose response of the TLD chip. Broadly, our results are consistent with existing data, which show a marked difference in the energy dependence of the two materials. However, the precision of our measurements (standard uncertainty of about 0.6%) has permitted the identification of features that have not been noted before. In particular, the energy dependence of the two materials is quite different in the important energy region delimited by 137Cs and 60Co gamma rays. PMID:14653324

  17. Type testing of a new TLD for the UK Health Protection Agency.

    PubMed

    Gilvin, P J; Baker, S T; Daniels, T J; Eakins, J D; McClure, D R; Bartlett, D T; Boucher, C

    2008-01-01

    The UK Health Protection Agency is currently commissioning a new personal dosimetry system based on the use of Harshaw two-element thermoluminescent dosemeter cards using LiF:Mg,Cu,P. Results of extensive type testing carried out with reference to IEC 61066, "Thermoluminescence Dosimetry Systems for Personal and Environmental Monitoring", have been presented. PMID:17513291

  18. Extremity dosimetry trial: Devonport Royal Dockyard.

    PubMed

    Kenyon, Rob; Collison, Roger

    2008-01-01

    This trial was undertaken to assess extremity dosemeters, which were made available to Devonport Royal Dockyard and determine the most suitable to the site. The trial included operational and laboratory-based exposures. Operational exposures were within a submarine reactor compartment and a waste storage area. Laboratory exposures were undertaken using (241)Am, (137)Cs and (60)Co sources to compare and contrast the dosemeters energy response. In addition, the low dose response and the response if placed in the incorrect orientation were also assessed. Ten passive and two active dosemeters were tested, with three highlighted as the most technically suitable, DSTL Harshaw DXT-RAD, HPA Harshaw EXT-RAD and the AMEC Panasonic UD-807A. The most technically suitable dosemeter was the DSTL Harshaw DXT-RAD, due to good responses within all aspects of the trial and the user's preference for the ring type design. The John Caunt ED2 electronic dosemeter 2 (ED2) also performed well, but suffered radio frequency interference. PMID:18319280

  19. Energy response of different types of RADOS personal dosemeters with MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P) TL detectors.

    PubMed

    Obryk, B; Hranitzky, C; Stadtmann, H; Budzanowski, M; Olko, P

    2011-03-01

    The photon energy response of different RADOS (Mirion Technologies) personal dosemeters with MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P) thermoluminescence (TL) detectors was investigated. Three types of badges were applied. The irradiation with reference photon radiation qualities N (the narrow spectrum series), and S-Cs and S-Co nuclide radiation qualities, specified in ISO 4037 [International Organization for Standardization (ISO). X and gamma reference radiations for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy. ISO 4037. Part 1-4 (1999)], in the energy range of 16-1250 keV, were performed at the Dosimetry Laboratory Seibersdorf. The results demonstrated that a readout of a single MTS-N or MCP-N detector under the Al filter can be used to determine Hp(10) according to requirements of IEC 61066 [International Electrotechnical Commission (IEC). Thermoluminescence dosimetry systems for personal and environmental monitoring. International Standard IEC 61066 (2006)] for TL systems for personal dosimetry. The new RADOS badge with the experimental type of a holder (i.e. Cu/Al filters) is a very good tool for identifying the radiation quality (photon energy). PMID:21227957

  20. Intercomparison exercise within a distributed-dosimetry network.

    PubMed

    Romanyukha, A; Voss, S P; Benevides, L A

    2011-03-01

    The results of an intercomparison exercise within the US Navy dosimetric network (USN-DN) are presented and discussed. The USN-DN uses a commercially available LiF:Mg,Cu,P thermoluminescent dosemeter (TLD) model Harshaw 8840/8841 and TLD reader model Harshaw 8800 manufactured by Thermo Fisher Scientific. The USN-DN consists of a single calibration facility and 16 satellite dosimetry reading facilities throughout the world with ∼ 40 model 8800 TLD readers and in excess of 350 000 TLD cards in circulation. The Naval Dosimetry Center (NDC) is the primary calibration site responsible for the distribution and calibration of all TLD cards and their associated holders. In turn, each satellite facility is assigned a subpopulation of cards, which are utilised for servicing their local customers. Consistency of the NDC calibration of 150 dosemeters (calibrated at NDC) and 27 locally calibrated remote readers was evaluated in the framework of this intercomparison. Accuracy of TLDs' calibration, performed at the NDC, was found to be <3 % throughout the entire network. Accuracy of the readers' calibration, performed with the NDC issued calibration dosemeters at remote sites, was found to be better than 4 % for most readers. The worst performance was found for reader Channel 3, which is calibrated using the thinnest chip of the Harshaw 8840/8841 dosemeter. The loss of sensitivity of this chip may be caused by time-temperature profile that has been designed for all four chips without consideration of chip thickness. PMID:21088021

  1. Analysis of anomalous data produced by Harshaw Model 8801 thermoluminescent dosimeter cards

    SciTech Connect

    Sonder, E.; Ahmed, A.B.

    1993-05-01

    A large number of dosimeters that have produced abnormal data during field assignment have been stored, reirradiated, and studied. Results are summarized and comparisons are made with normal dosimeters. Summarized here are anomalous glow curve shapes, distributions of anomalies in the residual luminescent responses, and historical and repeat-irradiation behavior of abnormal dosimeters. The results indicate that by far the most frequent abnormal data involve elevated readings from Chip 3, accompanied by excess luminescence at temperatures higher than that of the normal radiation produced band. There is no sharp division between normal and abnormal dosimeters (dosimeters yielding excess luminescence at high temperature). Rather, dosimeters exhibit a continuum of behavior from very good (little high temperature luminescence) to clearly abnormal behavior. The excess luminescence emitted at high temperature in abnormal dosimeters is not proportional to absorbed dose; it has a radiation-independent average value that depends on the dosimeter but varies erratically above and below that average for consecutive anneals. At relatively high radiation exposures (>100 mR), the amount of excess high temperature luminescence becomes unimportant and abnormal data are rare.

  2. Long-term stability of Harshaw LiF:Mg,Cu,P TLDS.

    PubMed

    Gilvin, P J; Burkett, R A; Baker, S T; Garratt, N J

    2011-03-01

    The sensitivity of Harshaw™ magnesium/copper/phosphorus-doped lithium fluoride is shown to be stable over long time periods, even when, as is often the case in practical operations, the TLDs are read out only three times a year. PMID:21216732

  3. The effect of visible light on Harshaw Model 8801 thermoluminescent dosimeters

    SciTech Connect

    Sonder, E.; Ahmed, A.B.; McMahan, K.L.; Colwell, D.S.; Smith, P.R.

    1990-09-01

    It has been known for some time that illumination of lithium fluoride (LiF) thermoluminescent dosimeters, particularly with ultraviolet wavelengths, causes these dosimeters to emit thermoluminescence (TL), similar to that caused by exposure to radiation. However the effect of incandescent light on dosimeters is not well documented. In this study the growth, saturation and spectral dependence of this luminescence is studied for open dosimeter cards illuminated with room incandescent light, and for dosimeters inside their holders exposed to bright sunlight. The results confirm that illumination with room light does give rise to luminescence in unirradiated dosimeters. Light in the ultraviolet is an order of magnitude more efficient in producing this TL than is longer wave length (red) visible light. The illumination-induced TL saturates at intensities that correspond to TL produced by exposure of about 70 mR of {sup 137}Cs; thus illumination clearly can give rise to false radiation exposure reports. Moreover it was fund that the dosimeter holder allows enough light to enter so that exposure of dosimeters to bright sunlight will activate some of the chips of the dosimeter cards in a fashion identical to that of room light. The glow curves produced by light are broader than those produced by gamma irradiation and a series of experiments have confirmed that the light induced TL comes from the Teflon sheets holding the LiF dosimeters, rather than the LiF chips themselves. 13 refs., 5 figs., 2 tabs.

  4. Long-term stability of a TLD-based individual monitoring system.

    PubMed

    Alves, J G; Abrantes, J N; Margo, O; Rangel, S; Santos, L

    2006-01-01

    The thermoluminescence dosemeter (TLD) system at the Individual Monitoring Service (IMS) of the Nuclear Technology Institute (ITN) at the Radiological Protection and Nuclear Safety Department (DPRSN) comprises two 6600 Harshaw readers and the Harshaw 8814 TL card and the holder containing two LiF:Mg,Ti (TLD-100) dosemeters for the evaluation of H(p)(10) and H(p)(0.07). The readers are calibrated on a monthly basis and as part of the quality assurance programme implemented at the IMS a set of dosemeters is issued monthly to the DPRSN's Standard Dosimetry Laboratory for linearity measurements. The results obtained since November 2001 are presented. Fading and sensitivity change experiments are carried out every month covering 8 week periods so that enough time is given to simulate issuing, integrating and receiving times and respective delays. A set of 96 dosemeters organised in eight subsets of 12 are used. In each subset, four dosemeters are irradiated and stored at room temperature (RT), four are not irradiated at all and the last four are irradiated after storage. The 12 dosemeters of each subset are readout at the same time, one per week, covering the 8 week period. The results from the sets irradiated and stored at different periods allowed for the evaluation of fading and sensitivity changes experienced over the whole monitoring period and respective preparation time and readout delays. Time evolution charts of the reader calibration factors, of the linearity parameters and of the evolution of the integrated area in the region of dosimetric interest with storage at RT were obtained. This paper aims to quantify the long-term stability of the TLD system in use at the IMS. PMID:16987916

  5. LiF:Mg,Cu,P glow curve shape dependence on heating rate.

    PubMed

    Luo, L Z; Velbeck, K J; Moscovitch, M; Rotunda, J E

    2006-01-01

    The glow curve shape of LiF:Mg,Cu,P (MCP) material is studied in this research. The study is focused on the effects of the heating rate on the dosimetric peaks. Different configurations of dosemeters (chips, cards and powder) are studied. The shifting of the dominant dosimetric peak is observed and analysed. The curves are deconvoluted using the new Harshaw Glow Curve Analyser (GCA) program. Results of the study are presented, as well as possible explanations as to the observed effects. PMID:16581930

  6. Preliminary results on bubble detector as personal neutron dosemeter.

    PubMed

    Ponraju, D; Krishnan, H; Viswanathan, S; Indira, R

    2011-03-01

    The bubble detector is demonstrated as one of the best suitable neutron detectors for neutron dose rate measurements in the presence of high-intense gamma fields. Immobilisation of a volatile liquid in a superheated state and achieving uniform distribution of tiny superheated droplets were a practical challenge. A compact and reusable bubble detector with high neutron sensitivity has been developed at the Indira Gandhi Centre for Atomic Research by immobilising the superheated droplets in a suitable polymer matrix. Two types of bubble detectors have been successfully developed, one by incorporating isobutane for measuring fast neutron and another by incorporating Freon-12 for both fast and thermal neutron. The performance of the detector has been tested using 5 Ci Am-Be neutron source and the results are described. PMID:21217133

  7. Lithium-gadolinium-borate as a neutron dosemeter.

    PubMed

    Lewis, D V; Spyrou, N M; Williams, A M; Beeley, P A

    2007-01-01

    Lithium-gadolinium-borate (LGB) dispersed as microcrystals within the plastic scintillator BC-490 is a promising material for accurate neutron dosimetry in mixed n/gamma fields. Spectral information > 1 MeV is obtained by capture gating proton recoil events in the plastic scintillator to subsequent capture in (6)Li. Below 1 MeV, isolated capture events in either gadolinium or (6)Li give energy information in this region. Discrimination based on capture gating is used to reject false coincidences due to gamma rays or incorrectly gated neutron events. A detailed Monte Carlo model has been created in MCNPX that predicts the energy response of the LGB spectrometer in the capture-gated mode of operation. X-ray microtomography has been performed on the detector in order to obtain the LGB microcrystal distribution within the plastic scintillator, and this is incorporated into the model. The way in which the calculated response functions can be included in an unfolding procedure is outlined. PMID:17578875

  8. Chapter I: Geology of a Middle Tertiary Clay Deposit in thePatagonia Mountains near Harshaw, Santa Cruz County, Southeastern Arizona

    USGS Publications Warehouse

    Houser, Brenda B.

    2005-01-01

    A middle Tertiary rhyolite tuff on the northeast side of the Patagonia Mountains in Santa Cruz County, southeastern Arizona contains lenses of calcareous low-swelling montmorillonite clay, as much as 10 to 15 m thick. The presence of the tuff has been known for years, but the clay has not been described previously. The clay lenses, which are virtually silt- and sand-free, were probably formed by diagenetic alteration of fairly clean ash-fall-tuff beds. In preliminary tests, the clay exhibited only about 9 percent shrinkage on drying and about 1 percent shrinkage on firing. Cracking and distortion were minimal in both drying and firing. Further testing needs to be done on the clay to determine its suitability as a specialty clay or as an additive to other clays.

  9. A study on the behaviour of TLD-100 glow peaks at extreme ambient temperatures in Riyadh, Saudi Arabia.

    PubMed

    Al-Haj, Abdalla N; Lagarde, Charlie S

    2006-01-01

    In this study, the temperature-induced variations in the TLD-100 response and the modifications in its glow peaks are investigated in real environmental exposure conditions in Riyadh, Saudi Arabia, where ambient temperatures during summer reach >45 degrees C and with relative humidity of <10%. Three groups of 12 TLD-100 cards in Harshaw type 8814 TLD cardholders were deployed as environmental dosemeters for a period of approximately 1 month for 12 consecutive months. One group was irradiated to 5 mGy 137Cs prior to deployment; another was irradiated to the same dose after deployment, while the last group was left unirradiated. Analysis of glow curves was done using commercially available glow curve deconvolution software (CGCD). Monthly variations in peak 3, 4 and 5 areas relative to the corresponding peak areas of a prompt glow curve are presented. Results of this study show good TL signal compensation between peaks 4 and 5 at all ambient temperatures encountered in this experiment, despite the observed individual variations experienced by each of these peaks. The sum of peak 4 and 5 areas is constant to within approximately 10%, for both pre- and post-irradiated dosemeters, during this 12-month cycle. PMID:16735566

  10. Ten years of monitoring the occupational radiation exposure in Bosnia and Herzegovina.

    PubMed

    Basić, B; Beganović, A; Samek, D; Skopljak-Beganović, A; Gazdić-Santić, M

    2010-01-01

    Monitoring of occupationally exposed persons in Bosnia and Herzegovina started in 1960s and it was interrupted in 1992. Dosimetry service resumed in 1999 when the International Atomic Energy Agency provided Harshaw 4500 TLD-reader and the first set of TLDs for the Radiation Protection Centre (RPC) of the Institute of Public Health of the Federation of Bosnia and Herzegovina. In January 2009, the RPC covered 1279 professionals with personal dosimetry, which is more than 70 % of all radiation workers in the country. Most of the TLD users work in medical institutions. In period 1999-2003 RPC provided 984 workers with dosemeters. In the next 5 y period (2004-2008), the number of persons covered by dosimetry increased by an average of 51 %. The mean and collective effective dose in the period 1999-2003 were 1.55 mSv and 1.54 personSv, respectively. In the period 2004-2008, the mean doses changed by 1 % on average, but the collective effective dose increased by 53 % for all practices. Mean and collective effective dose were 1.57 mSv and 2.34 personSv, respectively. The highest personal doses are associated with industrial radiography, than exposures in nuclear medicine. Radiology plays a significant role in collective dose only, whereas other exposures are low. Results correspond to results found in the literature. New practices in industry and medicine emphasise the need for more personal dosemeters, as well as specialised dosemeters for extremities monitoring, etc. PMID:20150230

  11. Detection of thermal neutrons with a CMOS pixel sensor for a future dosemeter

    SciTech Connect

    Vanstalle, M.; Husson, D.; Higueret, S.; Le, T. D.; Nourreddine, A. M.

    2011-07-01

    The RaMsEs group (Radioprotection et Mesures Environnementales) is developing a new compact device for operational neutron dosimetry. The electronic part of the detector is made of an integrated active pixel sensor, originally designed for tracking in particle physics. This device has useful features for neutrons, such as high detection efficiency for charged particles, good radiation resistance, high readout speed, low power consumption and high rejection of photon background. A good response of the device to fast neutrons has already been demonstrated [1]. In order to test the sensibility of the detector to thermal neutrons, experiments have been carried out with a 512 x 512 pixel CMOS sensor on a californium source moderated with heavy water (Cf.D{sub 2}O) on the Van Gogh irradiator at the LMDN, IRSN, Cadarache (France)). A thin boron converter is used to benefit from the significant cross section of the {sup 10}B (n,{alpha}) {sup 7}Li reaction. Results show a high detection efficiency (around 10{sup -3}) of the device to thermal neutrons. Our measurements are in good agreement with GEANT4 Monte Carlo simulations. (authors)

  12. Thermoluminescence solid-state nanodosimetry—the peak 5A/5 dosemeter

    PubMed Central

    Fuks, E.; Horowitz, Y. S.; Horowitz, A.; Oster, L.; Marino, S.; Rainer, M.; Rosenfeld, A.; Datz, H.

    2011-01-01

    The shape of composite peak 5 in the glow curve of LiF:Mg,Ti (TLD-100) following 90Sr/90Y beta irradiation, previously demonstrated to be dependent on the cooling rate used in the 400°C pre-irradiation anneal, is shown to be dependent on ionisation density in both naturally cooled and slow-cooled samples. Following heavy-charged particle high-ionisation density (HID) irradiation, the temperature of composite peak 5 decreases by ∼5°C and the peak becomes broader. This behaviour is attributed to an increase in the relative intensity of peak 5a (a low-temperature satellite of peak 5). The relative intensity of peak 5a is estimated using a computerised glow curve deconvolution code based on first-order kinetics. The analysis uses kinetic parameters for peaks 4 and 5 determined from ancillary measurements resulting in nearly ‘single-glow peak’ curves for both the peaks. In the slow-cooled samples, owing to the increased relative intensity of peak 5a compared with the naturally cooled samples, the precision of the measurement of the 5a/5 intensity ratio is found to be ∼15 % (1 SD) compared with ∼25 % for the naturally cooled samples. The ratio of peak 5a/5 in the slow-cooled samples is found to increase systematically and gradually through a variety of radiation fields from a minimum value of 0.13±0.02 for 90Sr/90Y low-ionisation density irradiations to a maximum value of ∼0.8 for 20 MeV Cu and I ion HID irradiations. Irradiation by low-energy electrons of energy 0.1–1.5 keV results in values between 1.27 and 0.95, respectively. The increasing values of the ratio of peak 5a/5 with increasing ionisation density demonstrate the viability of the concept of the peak 5a/5 nanodosemeter and its potential in the measurement of average ionisation density in a ‘nanoscopic’ mass containing the trapping centre/luminescent centre spatially correlated molecule giving rise to composite peak 5. PMID:21149323

  13. Alarm inhalation dosemeter for long living radioactive dust due to an uncontrolled release

    SciTech Connect

    Streil, T.; Oeser, V.; Rambousky, R.; Buchholz, F. W.

    2008-08-07

    MyRIAM is the acronym for My Radioactivity In Air Monitor and points out that the device was designed for personal use to detect any radioactivity in the air at the place and at the moment of danger. The active air sampling process enables a detection limit several orders of magnitude below that of Gamma detectors. Therefore, it is the unique way to detect dangerous exposures in time.Individual protection against inhalation of long living radioactive dust (LLRD) saves human life and health. LLRD may occur in natural environment as well as in case of nuclear accidence or military and terrorist attacks. But in any case, the immediate warning of the population is of great importance. Keep in mind: it is very easy to avoid LLRD inhalation--but you have to recognize the imminent danger. The second requirement of gap-less documentation and reliable assessment of any derived LLRD exposure is building the link to Dosimetry applications.The paper demonstrates the possibility to design small and low cost air samplers, which can be used as personal alarm dosimeters and fulfil the requirements mentioned above.Several test measurements taken by a mobile phone sized MyRIAM, shall be used to demonstrate the correctness of this statement.

  14. Alarm inhalation dosemeter for long living radioactive dust due to an uncontrolled release

    NASA Astrophysics Data System (ADS)

    Streil, T.; Oeser, V.; Rambousky, R.; Buchholz, F. W.

    2008-08-01

    MyRIAM is the acronym for My Radioactivity In Air Monitor and points out that the device was designed for personal use to detect any radioactivity in the air at the place and at the moment of danger. The active air sampling process enables a detection limit several orders of magnitude below that of Gamma detectors. Therefore, it is the unique way to detect dangerous exposures in time. Individual protection against inhalation of long living radioactive dust (LLRD) saves human life and health. LLRD may occur in natural environment as well as in case of nuclear accidence or military and terrorist attacks. But in any case, the immediate warning of the population is of great importance. Keep in mind: it is very easy to avoid LLRD inhalationbut you have to recognize the imminent danger. The second requirement of gap-less documentation and reliable assessment of any derived LLRD exposure is building the link to Dosimetry applications. The paper demonstrates the possibility to design small and low cost air samplers, which can be used as personal alarm dosimeters and fulfil the requirements mentioned above. Several test measurements taken by a mobile phone sized MyRIAM, shall be used to demonstrate the correctness of this statement.

  15. Thermoluminescent spectra of rare earth doped MgB4O7 dosemeters.

    PubMed

    Karali, T; Rowlands, A P; Prokic, M; Townsend, P D; Halmagean, E

    2002-01-01

    This paper presents X ray excited TL spectra of magnesium borate doped with either single rare earth ions Dy or Tm, or co-doped with Dy/Tm, Tm/Mn or Dy/Tb. Intrinsic emission from the host material is in the UV/blue region at approximately 375 nm, with a tail extending to 200 nm. The main dosimetric peak is detected at approximately 180 degrees C but slight differences are noted between the glow peak maxima from the different rare earth ions and there were changes following thermal treatments. The results are discussed according to the interaction between trapping and rare earth sites. PMID:12382891

  16. A comparison of personal dose equivalent measurements made by personal dosemeters

    NASA Astrophysics Data System (ADS)

    Cechak, T.; Davidkova, J.; Kodl, O.; Novacek, P.; Papirnik, P.; Petrova, K.; Prasek, P.; Martincik, J.; Sochor, V.

    2014-11-01

    Individual monitoring services for external radiation were tested in the Czech Republic. The results of the tests show that they are dosimetry systems authorized and regularly tested in the Czech Republic having outliers for low energy region and angle of 50 degree and greater. With the highest probability, it can be stated that the processing equipment does not determine the angle of exposure reliably. These cases may have caused overestimations of Hp(10) in the special conditions occurring e.g. in interventional radiology and cardiology procedures.

  17. Elimination of redundant thermoluminescent dosemeter monitoring at Oyster Creek nuclear generating station

    SciTech Connect

    Schwartz, P.E.

    1989-01-01

    The Oyster Creek direct radiation monitoring network has long been operating using several time-scale measurements. This network is used to assess the radiation levels during normal plant operations as well as to set the background radiation levels used to determine the radiological impact of a nonroutine release of radioactivity from the plant. Through analysis of the behavior of the monthly and quarterly activity of several types of direct radiation monitoring, the successful elimination of redundant and artificially high measurement techniques has been done in concert with providing the community with most efficient direct radiation monitoring methods. Dose rates from external radiation sources are measured around licensed U.S. Nuclear Regulatory Commission (NRC) facilities using passive detectors known as thermoluminescent dosimeters (TLDs). These detectors provide a quantitative measurement of the radiation levels in the are in which they are placed. The detected radiation could be the result of cosmic or naturally occurring origin in the air and on the ground, prior nuclear weapons testing, and activity from a nuclear facility. This paper describes the TLD network placed around the Oyster Creek nuclear generating station (OCNGS) and the comparisons between TLDs of different manufacturers and of different resident times and the successful elimination of the less accurate monthly TLD for the purpose of cost containment.

  18. CW-OSL measurement protocols using optical fibre Al2O3:C dosemeters.

    PubMed

    Edmund, J M; Andersen, C E; Marckmann, C J; Aznar, M C; Akselrod, M S; Btter-Jensen, L

    2006-01-01

    A new system for in vivo dosimetry during radiotherapy has been introduced. Luminescence signals from a small crystal of carbon-doped aluminium oxide (Al2O3:C) are transmitted through an optical fibre cable to an instrument that contains optical filters, a photomultiplier tube and a green (532 nm) laser. The prime output is continuous wave optically stimulated luminescence (CW-OSL) used for the measurement of the integrated dose. We demonstrate a measurement protocol with high reproducibility and improved linearity, which is suitable for clinical dosimetry. A crystal-specific minimum pre-dose is necessary for signal stabilisation. Simple background subtraction only partially removes the residual signal present at long integration times. Instead, the measurement protocol separates the decay curve into three individual components and only the fast and medium components were used. PMID:16990348

  19. Occupational exposure doses in interventional procedures in Bosnia and Herzegovina.

    PubMed

    Bašić, B; Beganović, A; Skopljak-Beganović, A; Samek, D

    2011-03-01

    Monitoring of occupationally exposed workers in Bosnia and Herzegovina started in 1960s and it was interrupted in 1992. Dosimetry service resumed in 1999 when the International Atomic Energy Agency provided Radiation Protection Centre with Harshaw 4500 Thermoluminescence dosemeter (TLD)-reader and the first set of TLDs. The highest doses are received by professionals working in interventional procedures (radiology, cardiology, gastroenterohepatology etc.). Number of these procedures is increasing each year (just in cardiology this increase is 24 % per year). Results from two TLDs are used to estimate effective dose. One is worn under the apron (chest level), and the other above (neck level). Calculation is performed using Niklason's methodology. Total number of occupationally exposed persons in interventional radiology is 90. The collective dose they receive is 67 person mSv, while the mean dose is 0.77 mSv (based on 12-month period). Highest doses are received by physicians (3.7 mSv), while radiographers and nurses receive 2.1 and 1.9 mSv respectively. This occurs due to the fact that physicians stand closer to the source (patient). The lead apron is proven to be the most efficient radiation protection equipment, but, also, lead thyroid shield and glasses can significantly lower doses received by professionals. The use of this equipment is highly recommended. PMID:21138927

  20. Lithium fluoride detectors for recording gamma rays over a wide dose range

    SciTech Connect

    Erkin, V.G.; Persinen, A.A.

    1987-02-01

    The authors have combined thermoluminescent and spectrophotometric methods to measure doses in the range 1 x 10/sup -4/ to 6 x 10/sup 5/ Gy with DTG-4 detectors of diameter 5 mm and thickness 1 mm. We used a /sup 60/Co or /sup 137/Cs source (doses 10/sup -4/-10 Gy), as well as an MRKh-..gamma..-20 apparatus (doses of 10/sup 2/-6 x 10/sup 5/ Gy). The gamma doses were monitored with a set of ionization chambers in the VA-J-18 apparatus as well as with ferrous sulfate dosemeters. The light sum was recorded over the range 20-200/sup 0/C with a Harshaw model 2000-D instrument and with a KDT-1. The optical absorption spectra were measured with an SF-26 spectrophotometer over the range 200-600 nm. The detectors were irradiated in batches of five for each dose in plastic cassettes providing obedience to the electron-equilibrium conditions.

  1. Assessment of medical occupational radiation doses in Costa Rica.

    PubMed

    Mora, P; Acuña, M

    2011-09-01

    Participation of the University of Costa Rica (UCR) in activities in an IAEA Regional Project RLA/9/066 through training, equipment and expert missions, has enabled to setting up of a national personal monitoring laboratory. Since 2007, the UCR has been in charge of monitoring around 1800 medical radiation workers of the Social Security System. Individual external doses are measured with thermoluminescent dosemeter using a Harshaw 6600 Plus reader. The service has accreditation with ISO/IEC 17025:2005. Distribution of monitored medical personnel is as follows: 83 % in diagnostic radiology, 6 % in nuclear medicine and 6 % in radiotherapy. Preliminary values for the 75 percentile of annual H(p)(10) in mSv are: radiology 0.37; interventional radiology 0.41; radiotherapy 0.53 and nuclear medicine 1.55. The service provided by the UCR in a steady and reliable way can help to implement actions to limit the doses received by the medical workers and optimise their radiation protection programs. PMID:21856694

  2. Discrimination of photon from proton irradiation using glow curve feature extraction and vector analysis.

    PubMed

    Skopec, M; Loew, M; Price, J L; Guardala, N; Moscovitch, M

    2006-01-01

    Two types of thermoluminescence dosemeters (TLDs), the Harshaw LiF:Mg,Ti (TLD-100) and CaF(2):Tm (TLD-300) were investigated for their glow curve response to separate photon and proton irradiations. The TLDs were exposed to gamma irradiation from a (137)Cs source and proton irradiation using a positive ion accelerator. The glow curve peak structure for each individual TLD exposure was deconvolved to obtain peak height, width, and position. Simulated mixed-field glow curves were obtained by superposition of the experimentally obtained single field exposures. Feature vectors were composed of two kinds of features: those from deconvolution and those taken in the neighbourhood of several glow curve peaks. The inner product of the feature vectors was used to discriminate among the pure photon, pure proton and simulated mixed-field irradiations. In the pure cases, identification of radiation types is both straightforward and effective. Mixed-field discrimination did not succeed using deconvolution features, but the peak-neighbourhood features proved to discriminate reliably. PMID:16614091

  3. Development of a TL detector for neutron measurement by CaSO4:Dy phosphors.

    PubMed

    Yang, Jeong-Seon; Kim, Jang-Lyul; Kim, Doo-Young; Chang, Si-Young

    2004-01-01

    Personal neutron dosimetry is quite a difficult area because a neutron is always accompanied with gamma radiation, which is required of a capability for mixed field dosimetry. CaSO4:Dy phosphor is known to have a very high sensitivity to gamma radiation, but the neutron capture cross section of the constituents of CaSO4:Dy are so small that the interactions between the thermal neutron and the phosphor are rare. One method to improve the neutron interaction is by introducing an impurity ion with a large thermal neutron captures cross section into the phosphor to act as a neutron target centre such as 6Li. In neutron-gamma mixed radiation fields, if two detectors for the 6Li-7Li compounds embedded CaSO4:Dy thermoluminescent (TL) pellets are used, a 6Li-compound embedded pellet can detect the neutron and gamma radiations together, and the other pellet can only detect the gamma radiation. Recently, the Korea Atomic Energy Research Institute (KAERI) has developed a new type of CaSO4:Dy TL materials embedded with phosphorous (KCT-300) to detect beta and gamma radiation with a very high sensitivity. This paper presents the development of CaSO4:Dy TL pellets embedded with 6Li compound for a thermal neutron measurement, and the detection method of the neutron and gamma dose in mixed fields with CaSO4:Dy TL pellets embedded with a 6Li compound (KCT-306) and CaSO4:Dy TL pellets embedded with a 7Li compound (KCT-307) is introduced. The net neutron sensitivity of CaSO4:Dy TL pellets embedded with 6Li compound developed in this study is about two times higher than that of the TLD-600 (Harshaw Chemical) dosemeter which is available commercially. PMID:15353663

  4. Pre- and post-irradiation fading effect for LiF:Mg,Ti and LiF:Mg,Cu,P materials used in routine monitoring.

    PubMed

    Carinou, E; Askounis, P; Dimitropoulou, F; Kiranos, G; Kyrgiakou, H; Nirgianaki, E; Papadomarkaki, E; Kamenopoulou, V

    2011-03-01

    LiF is a well-known thermoluminescent (TL) material used in individual monitoring, and its fading characteristics have been studied for years. In the present study, the fading characteristics (for a period of 150 d) of various commercial LiF materials with different dopants have been evaluated. The materials used in the study are those used in routine procedures by the Personal Dosimetry Department of Greek Atomic Energy Commission and in particular, LiF:Mg,Ti (MTS-N, TL Poland), LiF:Mg,Cu,P (MCP-N, TL Poland), LiF:Mg,Cu,P (MCP-Ns, thin active layer detector, TL Poland) and LiF:Mg,Cu,P (TLD100H, Harshaw). The study showed that there is a sensitivity loss in signal of up to 20 % for the MTS-N material for a 150-d period in the pre-irradiation fading phase. The MCP-N has a stable behaviour in the pre-irradiation fading phase, but this also depends on the readout system. As far as the post-irradiation fading effect is concerned, a decrease of up to 20 % for the MTS-N material is observed for the same time period. On the other hand, the LiF:Mg,Cu,P material presents a stable behaviour within ± 5 %. These results show that the fading effect is different for each material and should be taken into account when estimating doses from dosemeters that are in use for >2 months. PMID:21199822

  5. Response of TL materials to diagnostic radiology X radiation beams.

    PubMed

    Maia, Ana F; Caldas, Linda V E

    2010-01-01

    The main objective of this study was to carry out a direct performance comparison among some known types of TLDs-three types of CaSO(4):Dy pellets, sintered Al(2)O(3) pellets, LiF:Mg,Ti (Harshaw TLD-100), CaF(2):Dy (Harshaw TLD-200) and CaF(2):Mn (Harshaw TLD-400)-in the energy and dose ranges of diagnostic radiology beams. Several dosimetric characteristics were evaluated, such as reproducibility, sensitivity, calibration curves, lower dose limits and energy dependence. PMID:20097569

  6. Comparison of environmental TLD (thermoluminescent dosimeter) results obtained using glow curve deconvolution and region of interest analysis

    SciTech Connect

    Not Available

    1987-01-01

    We tested a Harshaw Model 4000 TLD Reader in the Sandia Environmental TLD Program. An extra set of LiF TLD-700 chips were prepared for each field location and calibration level. At the end of quarter one, half of the TLDs were read on the Model 4000 and the other half were read on our standard Harshaw Model 2000. This presentation compares the results of the two systems. The Model 4000 results are reported for two regions of interest and for background subtraction using Harshaw Glow Curve Deconvolution Software.

  7. Redox reactions in Cu-activated nanocrystalline LiF TLD phosphor

    NASA Astrophysics Data System (ADS)

    Singh, Manveer; Sahare, P. D.

    2012-10-01

    Samples of cubic shaped nanocrystalline LiF:Mg, LiF:Cu, LiF:P and LiF:Mg, Cu, P materials were synthesized through the chemical coprecipitation route. In case of LiF:Cu, it was predominantly doped with Cu2+ and Cu+ impurities using CuCl2 and Cu2Cl2 salts, respectively, as dopants. The samples were characterized by XRD, SEM and TEM techniques. The particle size observed from TEM photographs and XRD analysis was found to be in the range of 50-80 nm. Samples were annealed at different ambient temperatures in the range of 373-773 K. The pellets of these materials were exposed to γ-rays in the dose range (0.1 Gy-100 kGy) from 137Cs source for further studies. Thermoluminescence (TL) glow curves of these nanocrystalline samples show two main peaks one at around 404 K and another broad peak centered at around 490 K. The relative intensities of these peaks were found to change on doping with CuCl2 and Cu2Cl2. Comparison with commercially available TLD phosphors showed that TLD-700H and TLD-900 are more sensitive while, TLD-100 is less sensitive than LiF:Cu+ phosphor. The change in glow curve structures and the photoluminescence (PL) spectra revealed that the relative concentrations of the Cu2+ ↔ Cu+ ↔ Cu0 change irreversibly during irradiation, while taking TL readouts and during annealing beyond 523 K. It seems that such redox reactions are responsible for the changes in the sensitivity and the loss of the reusability of the phosphor as Cu+ is necessary for the high sensitivity of the phosphor. Further detailed studies by taking glow curve readouts up to different temperatures, irradiating again and taking TL readouts show that the remaining traps after the first readout could change the Cu2+/Cu+ ratio altering the glow curve structure. The PL spectra and ESR measurements of the irradiated samples also support these findings. It may be concluded that redox reactions are mainly responsible for the loss of sensitivity and reusability on taking TL after 523 K in case of LiF:Cu+ and LiF:Mg, Cu, P TLD phosphors. A model representing the redox reactions illustrates the TL phenomenon occurring in LiF:Cu+ phosphor.

  8. CaSO4:DY,Mn: A new and highly sensitive thermoluminescence phosphor for versatile dosimetry

    NASA Astrophysics Data System (ADS)

    Bahl, Shaila; Lochab, S. P.; Kumar, Pratik

    2016-02-01

    With the advent of newer techniques for dose reduction coupled with the development of more sensitive detectors, the radiation doses in radiological medical investigation are decreasing. Nevertheless, keeping the tenet in mind that all radiation doses could entail risk, there is a need to develop more sensitive dosimeters capable of measuring low doses. This paper gives the account of the development of a new and sensitive phosphor CaSO4:Dy,Mn and its characterization. The standard production procedure based on the recrystallization method was used to prepare CaSO4:Dy,Mn. The Thermoluminescence (TL) studies were carried out by exposing it with gamma radiation (Cs-137) from 10 μGy to 100 Gy. The theoretical studies to determine the number of peaks and kinetic parameters related to the TL glow peaks in CaSO4:Dy,Mn was performed using the Computerized Glow Curve Deconvolution (CGCD) method. Experiments were performed to determine optimum concentration of the dopants Dysprosium (Dy) and Mangnese (Mn) in the host CaSO4 so that maximum sensitivity of the phosphor may be achieved. The optimum dopant concentration turned out to be 0.1 mol%. As there were two dopants Dy and Mn their relative ratio were varied in steps of 0.025 keeping the concentration of total dopant (Dy and Mn) 0.1 mol% always. The maximum TL intensity was seen in the CaSO4:Dy(0.025),Mn(0.075) combination. The TL sensitivity of this phosphor was found to be about 2 and 1.8 times higher than that of popular phosphor CaSO4:Dy and LiF:Mg,Cu,P (TLD-700H) respectively. This new phosphor CaSO4:Dy,Mn showed fading of 11% which is similar to that of the standard phosphor CaSO4:Dy. The paper concludes that the new, highly sensitive TL phosphor CaSO4:Dy,Mn has shown higher sensitivity and hence the potential to replace commonly used CaSO4:Dy.

  9. Beta and low-energy photon irradiation of several commercial phosphors

    SciTech Connect

    Fix, J.J.; Holbrook, K.L.; Soldat, K.L.

    1983-02-01

    Several commercially available thermoluminescent phosphors were evaluated with respect to their observed response to selected beta sources and K-fluorescent x rays. Phosphor responses were determined for in-air and on-phantom irradiations. Similar irradiations were done using a /sup 137/Cs source. Phosphor glow curves were recorded using a Harshaw Model 2080 TL Picoprocessor.

  10. Beta and low-energy photon irradiation of several commercial phosphors

    NASA Astrophysics Data System (ADS)

    Fix, J. J.; Holbrook, K. L.; Soldat, K. L.

    1983-02-01

    Several commercially available thermoluminescent phosphors were evaluated with respect to their observed response to selected beta sources and K-fluorescent X rays. Phosphor responses were determined for in-air and on-phantom irradiations. Similar irradiations were done using a 137Cs source. Phosphor glow curves were recorded using a Harshaw Model 2080 TL Picoprocessor.

  11. Chemical and structural characterization of thermally degraded black chrome

    SciTech Connect

    Lampert, C.M.; Washburn, J.

    1980-06-01

    The very popular black chrome coating, Harshaw Chemical Company's Chromonyx, was characterized in terms of materials science to determine the nature of its microstructure and contribution to solar selectivity. The properties and degradation mode were revealed for samples heat treated at high temperatures. Principally, transmission and scanning electron microscopy, scanning Auger and energy dispersive X-ray analysis were employed for this microstructural characterization.

  12. ANIMAL COGNITION. Response to Comments on "Number-space mapping in the newborn chick resembles humans' mental number line".

    PubMed

    Rugani, Rosa; Vallortigara, Giorgio; Priftis, Konstantinos; Regolin, Lucia

    2015-06-26

    Mangalam and Karve raise concerns on whether our results demonstrate a mental number line, suggesting auxiliary experiments. Further data analyses show that their methodological concerns are not founded. Harshaw suggests that a side bias could have affected our results. We show that this concern is also unfounded. PMID:26113715

  13. Testing of Willow Clones for Biomass Production in Wisconsin

    SciTech Connect

    Kubiske, Marke E.

    2005-01-01

    A core experiment with 31 willow clones and 8 standard poplar clones was established at the Harshaw Experimental Farm, Rhinelander, WI in 1997. Data analysis is continuing for survival, growth, and biomass data for all willow test sites in this project.

  14. The response of the BTI bubble detectors in mixed gamma-neutron workplace fields.

    PubMed

    Vanhavere, F; Coeck, M; Lievens, B

    2007-01-01

    Bubble detectors have become a mature technology and are used as neutron dosemeters in a wide range of applications. At the SCK-CEN and Belgonuclaire they are used as official personal neutron dosemeter for the personnel. In the European Commission (EC) project of Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields (EVIDOS), a whole range of neutron dosemeters were irradiated in workplace fields in nuclear installations in Europe, including two types of bubble detectors. The responses of the bubble detectors are compared with the reference values determined using a directional spectrometer and a reference instrument to measure Hp(10). PMID:17533158

  15. Personnel neutron dosimetry

    SciTech Connect

    Hankins, D.

    1982-04-01

    This edited transcript of a presentation on personnel neutron discusses the accuracy of present dosimetry practices, requirements, calibration, dosemeter types, quality factors, operational problems, and dosimetry for a criticality accident. 32 figs. (ACR)

  16. Albedo neutron dosimetry in Germany: regulations and performance.

    PubMed

    Luszik-Bhadra, M; Zimbal, A; Busch, F; Eichelberger, A; Engelhardt, J; Figel, M; Frasch, G; Gnther, K; Jordan, M; Martini, E; Haninger, T; Rimpler, A; Seifert, R

    2014-12-01

    Personal neutron dosimetry has been performed in Germany using albedo dosemeters for >20 y. This paper describes the main principles, the national standards, regulations and recommendations, the quality management and the overall performance, giving some examples. PMID:24639589

  17. Beta dosimetry with newly developed graphite mixed TL detectors.

    PubMed

    Proki?, M S

    1985-04-01

    The characteristics of thermoluminescent dosemeters prepared from graphite mixed with sintered MgB4O7:Dy are presented for beta ray dosimetry. These dosemeters are attractive for beta ray dosimetry since the material combines low transparency with near tissue equivalence and high sensitivity, thus enabling skin dose to be assessed from low energy beta emitters in accordance with the ICRP recommendations. Results from practical field experiments are also presented. PMID:4001159

  18. Effect of phosphorus and other promoters on CoMo alumina hydrotreating catalysts

    SciTech Connect

    Stanulonis, J.J.; Pedersen, L.A.

    1980-01-01

    One-step impregnation with up to 2.5% by wt of phosphorus in the form of phosphoric acid produced a more active catalyst for hydrodenitrogenation but not for hydrodesulfurization of naphtha by comparison with an American Cyanamid Co. catalyst in which cobalt and molybdenum were supported on alumina. However, one-step impregnation did not guarantee good catalysts. The physical properties of the American Cyanamid and Harshaw Chemical Co. alumina supports were alike, but the activity similarity for both desulfurization and denitrogenation was between the Harshaw and Filtrol Corp. alumina supports. The promoting effects of the phosphoric acid and alumina were physical, but chemical action might also have been present. It appeared that if molybdenum is tied up in crystalline components, either the proper dispersion together with interaction is not achieved or the compounds physically block active sites.

  19. An investigation of false positive dosimetry results

    SciTech Connect

    Lewandowski, M.A.; Davis, S.A.; Goff, T.E.; Wu, C.F.

    1996-12-31

    The Waste Isolation Pilot Plant (WIPP) is a facility designed for the demonstration of the safe disposal of transuranic waste. Currently, the radiation source term is confined to sealed calibration and check sources since WIPP has not received waste for disposal. For several years the WIPP Dosimetry Group has operated a Harshaw Model 8800C reader to analyze Harshaw 8801-7776 thermoluminescent cards (3 TLD-700 and 1 TLD-600) with 8805 holder. The frequency of false positive results for quarterly dosimeter exchanges is higher than desired by the Dosimetry Group management. Initial observations suggested that exposure to intense ambient sunlight may be responsible for the majority of the false positive readings for element 3. A study was designed to investigate the possibility of light leaking through the holder and inducing a signal in element 3. This paper discusses the methods and results obtained, with special emphasis placed on recommendations to reduce the frequency of light-induced false positive readings.

  20. Dosimetric study of thermoluminescent detectors in clinical photon beams using liquid water and PMMA phantoms.

    PubMed

    Matsushima, Luciana C; Veneziani, Glauco R; Sakuraba, Roberto K; da Cruz, José C; Campos, Letícia L

    2012-07-01

    The purpose of this study was the dosimetric evaluation of thermoluminescent detectors of calcium sulphate doped with dysprosium (CaSO4:Dy) produced by IPEN compared to the TL response of lithium fluoride doped with magnesium and titanium (LiF:Mg,Ti) dosimeters and microdosimeters produced by Harshaw Chemical Company to clinical photon beams dosimetry (6 and 15 MV) using liquid water and PMMA phantoms. PMID:22341404

  1. Meeting Specifications Of Antares NaCl Laser Windows

    NASA Astrophysics Data System (ADS)

    Straughan, V. E.; Krus, D. J.

    1981-09-01

    This is a review article describing some of the techniques employed in meeting certain specifications for the fabrication of Antares 18" diameter NaC1 laser windows. Specifically, a pressure test for strength and window stability is described as well as a method for non-contact measurement of wedge angle and wedge direction utilizing a Fizeau 18" interferometer. Also the procedure followed at Harshaw in the mounting of windows is outlined.

  2. Current Challenges in Personal Dosimetry at the U.S. DOE Hanford Site

    SciTech Connect

    Rathbone, Bruce A. ); McDonald, Joseph C. ); Traub, Richard J. )

    2002-10-01

    Abstract - This paper presents an overview of the dosimetry system, dose equivalent calculation methodology, and QA/QC practices used at the U.S. Department of Energy Hanford site. It describes some of the problems encountered in accurately measuring dose equivalent quantities under a broad range of field conditions that do not necessarily correlate with laboratory calibration conditions and the approach taken to solve these problems. Personnel at Hanford are monitored with a combination of Harshaw model 8825 and 8816 thermoluminescent dosimeters and CR-39? track etch dosimeters. Extremities are monitored using the ICN MeasuRing loaded with a Harshaw XD740 chipstrate TLD. All dosimeters employ LiF:Mg,Ti elements that are read onsite with Harshaw model 8800 and 6600 TLD readers. CR-39? dosimeters are electrochemically etched in non-commercial etch chambers and counted with an automated track counting system developed by Pacific Northwest National Laboratory. Problems with over response of the 8825 with respect to Hp(0.07), under response of the 8825 with respect to Hp(3), and over response of the 8825 with respect to Hp(10) in Hanford's 90Sr/90Y beta radiation fields are discussed. Approaches to measurement of the operational quantities for field conditions and algorithm solutions to the above problems are described. Methods used to calibrate the ring dosimeter for Hanford field conditions together with limitations of the ring dosimeter in measuring Hp(0.07) for extremities, particularly when covered with protective clothing, are also discussed.

  3. Catalysts for NO/sub x/ reduction using ammonia

    SciTech Connect

    Darian, S.T.; Eldridge, J.W.; Kittrell, J.R.

    1982-05-01

    In the present work, two basically different catalyst compositions were studied. The first was a commercial catalyst, Harshaw V0301, approximately 10% vanadia supported on alumina; the second was a modified molecular-sieve catalyst prepared in our laboratories. The basic design employed for minimizing the pressure drop was that of a parallel-passage reactor, PPR, comprising a set of stainless-steel screens coated on both sides with catalyst particles and mounted in parallel on a steel-rod frame with spaces between them for passage of the gas flowing parallel to the screens. Of the three catalyst compositions tested, Harshaw V0301 was somewhat more active than the modified molecular sieve, MS I, but the improved modification, MS II, showed greater activity than the Harshaw catalyst. The NO/sub x/ conversion obtained with the modified molecular-sieve catalysts increases as reaction temperature increases, at least up to somewhere over 450/sup 0/ C. Preliminary design calculations and cost estimates for full-scale PPR units to control NO/sub x/ emissions from utility power plants indicate that this approach holds much promise for obtaining high NO/sub x/ conversions at high space velocities with low pressure drops, and also with attractively low capital investment and operating costs. 4 references, 8 figures, 1 table. (JMT)

  4. Catalytic methods for improved coal liquefaction and hydrotreating. Quarterly report No. 4, June 23-September 22, 1986. [Cyclohexene

    SciTech Connect

    Hirschon, A.S.; Laine, R.M.; Wilson, R.B. Jr.

    1986-10-01

    The goal of this project is to optimize the reaction conditions for liquefying coal and upgrading coal liquids. This quarter we concentrated on Tasks 1 and 2. In Task 1, Synthesis of Catalysts, we doped one of our organometallic-based NiMo catalysts with ruthenium to compare with the ruthenium-doped Harshaw catalyst (RuCoMo). We also added iron to the Harshaw-based RuCoMo catalyst to form an FeRuCoMo catalyst. In Task 2, HDN Activity of Catalysts with Model Systems, we furthered our efforts to study the mechanism and reactivity of the CoMo and RuCoMo catalysts. We studied cyclohexene under HDN conditions, in the presence of quinoline, and found that it is rapidly hydrogenated to cyclohexane but is not dehydrogenated to give benzene. We also tested and compared the Harshaw NiMo catalyst with the RuNiMo catalyst synthesized last quarter. We found the RuNiMo catalyst more active and more selective for HDN of quinoline to propylbenzene than the commercial NiMo catalyst. An organometallic-based RuNiMo catalyst was also tested and found to be very active and selective, but not as selective as the promoted commercial catalysts. The FeRuCoMo catalyst was tested and found to have activity similar to that of the CoMo catalyst; however, it has a higher selectivity to aromatic products. 4 refs., 8 figs., 3 tabs.

  5. Optimization of the photon response for a LiF thermoluminescent dosimeter

    SciTech Connect

    Carnell, R.C.

    1998-12-31

    A Harshaw LiF TLD card holder was optimized for maximum discrimination between different energies of irradiating photons in order to improve the dosimetric response. Since dose is proportional energy deposited, a theoretical model was created to estimate the TLD response by calculating the energy deposition. These results correlated with experimental data from NIST to within 20%. In order to increase the accuracy of the model, energy deposition calculations were made using the MCNP particle transport program. MCNP improved the correlation of the modeled data with the experimental data. Next, Harshaw`s 8825 card holder was optimized for photon energy determination by analyzing the card holder`s response with different filter materials and thickness. This analysis showed that increasing the copper filter thickness by 20 times and doubling the tin filter thickness compared to the original 8825 design improved the TLD`s photon energy determination response. The improved 8825 card holder was constructed and experiments were conducted at Armstrong Laboratories. The MCNP model predicted the experimental response of the card holder to within two standard deviations for all beams except M60. Finally, recommendations for a new card holder were made by Naval Dosimetry Center which included a modified filter for improved dose determination.

  6. Intercomparison 2013 on measurements of the personal dose equivalent Hp(10) in photon fields in the African region.

    PubMed

    Arib, M; Herrati, A; Dari, F; Ma, J; Lounis-Mokrani, Z

    2015-02-01

    An intercomparison exercise on the measurement of personal dose equivalent Hp(10) was jointly organised by the International Atomic Energy Agency and the Nuclear Research Centre of Algiers through its Secondary Standard Dosimetry Laboratory in the African region. This intercomparison exercise was aimed at verifying the performance of the individual monitoring services of the participants in order to assess their capabilities to measure the quantity Hp(10) in photon (gamma and X ray) fields helping them to comply with dose limitation requirements. The scope of this intercomparison was aimed at passive dosemeters, which determine the personal dose equivalent in photon radiation fields, mainly for thermoluminescence and optically stimulated luminescence dosemeters. Twenty-seven countries from the Africa region and from outside Africa participated in this exercise. The intercomparison protocol, including the preparation of the dosemeters and the irradiation procedures, is described and the results are presented, analysed and discussed. PMID:24982261

  7. Reference dosimetry measurements for the international intercomparison of criticality accident dosimetry SILENE 9-21 June 2002.

    PubMed

    Asselineau, B; Trompier, F; Texier, C; Iti, C; Mdioni, R; Tikunov, D; Muller, H; Pelcot, G

    2004-01-01

    An international intercomparison of criticality accident dosimetry systems took place in the SILENE reactor, in June 2002. Participants from 60 laboratories irradiated their dosemeters (physical and biological) using two different configurations of the reactor. In preparation for this intercomparison, the leakage radiation fields were characterised by spectrometry and dosimetry measurements using the ROSPEC spectrometer associated with a NE-213 scintillator, ionisation chambers, GM counters, diodes and thermoluminescence dosemeters (TLDs). For this intercomparison, a large area was required to irradiate the dosemeters both in free air and on phantoms. Therefore, measurements of the uniformity of the field were performed with activation detectors and TLDs for neutron and gammas, respectively. This paper describes the procedures used and the results obtained. PMID:15353691

  8. The use of passive environmental TLDs in the operation of the Spanish early warning network 'REVIRA'.

    PubMed

    Sez-Vergara, J C; Romero, A M; Vila Pena, M; Rodriguez, R; Muiz, J L

    2002-01-01

    As required by different international agreements, the regulatory body in Spain (Consejo de Seguridad Nuclear) implemented in 1992 a national automatic network (REVIRA) that continuously monitors radiation levels in order to give early warning of incidents having potential transboundary implications. The detector for environmental gamma-radiation dose rate is an active instrument based on a Geiger-Mller counter. However, the use of passive environmental dosemeters provides an additional low-cost dose estimate with an independent centralised calibration and even better basic features than active instruments. Since 1999, all 25 REVIRA stations have been monitored with passive TL environmental dosemeters based on LiF:Mg,Cu,P and operated according to the procedures established at Ciemat. This paper presents the obtained results and the further analysis considering differences in aspects such as photon energy response, inherent background or response to cosmic rays. The benefits of the use of passive environmental dosemeters in early warning networks are discussed. PMID:12382745

  9. Radon contribution to the total effective dose of uranium miners.

    PubMed

    Otahal, P; Burian, I; Nasir, M M; Gregor, Z

    2014-07-01

    Exposure to radon and its decay products is one of the three parts that create the total effective dose of uranium miners. Photons from gamma radiation and exposition to long-lived alpha emitters which are members of uranium family are the other two parts. The monthly total effective dose of uranium miners in mine Rozna I (Czech republic) is determined by the personal dosemeter ALGADE, which ensures the continual individual monitoring of all three parts. The exposed dosemeters are evaluated in the National Institute for Nuclear, Chemical and Biological Protection in Kamenna near Pribram. This paper describes the individual parts of miners' total effective dose considering the different types of work activities and workplaces. The main input data are the evaluation results of the uranium miners' personal dosemeters ALGADE in mine Rozna I in the time period from 2000 till 2012. PMID:24723187

  10. Microprocessor controlled portable TLD system

    NASA Technical Reports Server (NTRS)

    Apathy, I.; Deme, S.; Feher, I.

    1996-01-01

    An up-to-date microprocessor controlled thermoluminescence dosemeter (TLD) system for environmental and space dose measurements has been developed. The earlier version of the portable TLD system, Pille, was successfully used on Soviet orbital stations as well as on the US Space Shuttle, and for environmental monitoring. The new portable TLD system, Pille'95, consists of a reader and TL bulb dosemeters, and each dosemeter is provided with an EEPROM chip for automatic identification. The glow curve data are digitised and analysed by the program of the reader. The measured data and the identification number appear on the LED display of the reader. Up to several thousand measured data together with the glow curves can be stored on a removable flash memory card. The whole system is supplied either from built-in rechargeable batteries or from the mains of the space station.

  11. Dosimetry measurements using Timepix in mixed radiation fields induced by heavy ions; comparison with standard dosimetry methods

    PubMed Central

    Ploc, Ondrej; Kubancak, Jan; Sihver, Lembit; Uchihori, Yukio; Jakubek, Jan; Ambrozova, Iva; Molokanov, Alexander; Pinsky, Lawrence

    2014-01-01

    Objective of our research was to explore capabilities of Timepix for its use as a single dosemeter and LET spectrometer in mixed radiation fields created by heavy ions. We exposed it to radiation field (i) at heavy ion beams at HIMAC, Chiba, Japan, (ii) in the CERN's high-energy reference field (CERF) facility at Geneva, France/Switzerland, (iii) in the exposure room of the proton therapy laboratory at JINR, Dubna, Russia, and (iv) onboard aircraft. We compared the absolute values of dosimetric quantities obtained with Timepix and with other dosemeters and spectrometers like tissue-equivalent proportional counter (TEPC) Hawk, silicon detector Liulin, and track-etched detectors (TEDs).

  12. Dosimetry quality assurance in Martin Marietta Energy Systems` centralized external dosimetry system

    SciTech Connect

    Souleyrette, M.L.

    1992-10-23

    External dosimetry needs at the four Martin Marietta Energy Systems facilities are served by Energy Systems Centralized External Dosimetry System (CEDS). The CEDS is a four plant program with four dosimeter distribution centers and two dosimeter processing centers. Each plant has its own distribution center, while processing centers are located at ORNL and the Y-12 Plant. The program has been granted accreditation by the Department of Energy Laboratory Accreditation Program (DOELAP). The CEDS is a TLD based system which is responsible for whole-body beta-gamma, neutron, and extremity monitoring. Beta-gamma monitoring is performed using the Harshaw/Solon Technologies model 8805 dosimeter. Effective October 1, 1992 the standard silver mylar has been replaced with an Avery mylar foil blackened on the underside with ink. This was done in an effort to reduce the number of light induced suspect readings. At this time we have little operational experience with the new blackened mylars-The CEDS neutron dosimeter is the Harshaw model 8806B. This card/holder configuration contains two TLD-600/TLD-700 chip pairs; one pair is located beneath a cadmium filter and one pair is located beneath a plastic filter. In routine personnel monitoring the CEDS neutron dosimeter is always paired with a CEDS beta-gamma dosimeter.The CEDS extremity dosimeter is composed of a Harshaw thin TLD-700 dosiclip placed inside a Teledyne RB-4 finger sachet. The finger sachet provides approximately 7 mg/cm{sup 2} filtration over the chip. A teflon ring surrounds the dosiclip to help prevent tearing of the vinyl sachet.

  13. Dosimetry quality assurance in Martin Marietta Energy Systems' centralized external dosimetry system

    SciTech Connect

    Souleyrette, M.L.

    1992-10-23

    External dosimetry needs at the four Martin Marietta Energy Systems facilities are served by Energy Systems Centralized External Dosimetry System (CEDS). The CEDS is a four plant program with four dosimeter distribution centers and two dosimeter processing centers. Each plant has its own distribution center, while processing centers are located at ORNL and the Y-12 Plant. The program has been granted accreditation by the Department of Energy Laboratory Accreditation Program (DOELAP). The CEDS is a TLD based system which is responsible for whole-body beta-gamma, neutron, and extremity monitoring. Beta-gamma monitoring is performed using the Harshaw/Solon Technologies model 8805 dosimeter. Effective October 1, 1992 the standard silver mylar has been replaced with an Avery mylar foil blackened on the underside with ink. This was done in an effort to reduce the number of light induced suspect readings. At this time we have little operational experience with the new blackened mylars-The CEDS neutron dosimeter is the Harshaw model 8806B. This card/holder configuration contains two TLD-600/TLD-700 chip pairs; one pair is located beneath a cadmium filter and one pair is located beneath a plastic filter. In routine personnel monitoring the CEDS neutron dosimeter is always paired with a CEDS beta-gamma dosimeter.The CEDS extremity dosimeter is composed of a Harshaw thin TLD-700 dosiclip placed inside a Teledyne RB-4 finger sachet. The finger sachet provides approximately 7 mg/cm[sup 2] filtration over the chip. A teflon ring surrounds the dosiclip to help prevent tearing of the vinyl sachet.

  14. Liquefaction of bituminous coals using disposable ore catalysts and hydrogen. Final report, February 7, 1982-July 31, 1982

    SciTech Connect

    Mathur, V.K.

    1982-09-01

    There are a number of problems associated with the production of liquid fuels from coal. The most complex is the use of commercial catalysts which are expensive, with short life, and cannot be recovered or regenerated. The objective of this study was to conduct experiments on coal hydrogenation using low cost mineral ores as disposable catalysts. Coal samples from Blacksville Mine, Pittsburgh Bed were hydrogenated using a number of ores, ore concentrates and industrial waste products as catalysts. Experiments were also conducted using a commercial catalyst (Harshaw Chemicals, 0402T) and no catalyst at all to compare the results. Since iron pyrite has been reported to be a good disposable catalyst, experiments were also conducted using pyrite individually as well as in admixture with other ores or concentrates. The liquefaction was conducted at 425/sup 0/C under 2000 psig (13,790 kPa) hydrogen pressure for a reaction time of 30 minutes using SRC-II heavy distillate as a vehicle oil. The conclusions of this study are as follows: (a) Results of liquefaction using two cycle technique showed that the catalytic activity of iron pyrite could be enhanced by adding materials like limonite, laterite or red mud. Iron pyrite in admixture with limonite ore or molybdenum oxide concentrate gave the best results among all the binary mixtures studied. (b) Iron pyrite with molybdenum oxide concentrate and cobaltic hydroxide cake (metal loading in each case the same as in Harshaw catalyst) gave results which compared favorably with those obtained using the Harshaw catalyst. It is recommended that work on this project should be continued exploring other ores and their mixtures for their catalytic activity for coal liquefaction.

  15. Evaluation of commercially available TLD readers

    SciTech Connect

    Gulbin, J.; de Planque, G.

    1981-10-01

    The performance of two commercially available thermoluminescence bulb dosimetry systems, the Victoreen 2810 Ultra Sensitive TLD Reader and the Harshaw Model 2000P Bulb Dosimetry System, was investigated. Of primary interest was the reliability of the instruments at an exposure range typically encountered in environmental radiation when monitoring on a monthly basis, i.e., approx. 10 mR. Uniformity, linearity, and reproducibility test results are reported. The two systems were found to perform comparably well as bulb readers. Evaluation of the dual capability of the Victoreen 2810 as a chip reader is also described.

  16. A robotic manipulator for handling TLD badges.

    PubMed

    Levinson, S; Weinstein, M; Abraham, A; German, U; Gorelik, V; Rozenfeld, R; Hillel, S; Rodnay, G

    2008-11-01

    A prototype system for automatic handling of Harshaw/Bicron (now ThermoFisher Scientific) thermoluminescent dosimetry (TLD) badges, which is based on a robotic arm, was designed and built. The robot performs the loading and unloading of the TLD cards in the badges and transports them between the loading/unloading station and magazine stations. For quality assurance, a sticker containing the worker's details printed in barcode format was added to the badge. Automatic on-line identification is performed for checking the correlation between the badge and the TLD card number. PMID:18849713

  17. Improved catalysts for coal liquefaction: Quarterly report No. 10 for the period November 30, 1986 to February 28, 1987

    SciTech Connect

    Haynes, H.W. Jr.; McCormick, R.L.

    1987-03-24

    One deactivation run was completed during the last quarter using a catalyst prepared from a Harshaw/Filtrol titania support (JK02). This catalyst had a much lower surface area than the benchmark commercial catalyst (Amocat 1A) and consequent lower hydrogenation activity. The JK02 catalysts maintained its activity very well however and deactivation paralleled that of the benchmark catalyst. Silica-magnesia and nitrided activated carbon were tested as catalyst supports in batch reactor initial activity studies. Silica-magnesia did not perform well but a nitrided activated carbon supported catalyst has been selected for activity maintenance testing in the next quarter. 10 refs., 5 figs., 11 tabs.

  18. Relative thermoluminescent response of LiF-TLD to 4 keV X-rays

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Kalef-Ezra, J.

    The relative thermoluminescent response of 4 keV X-rays to 60Co gamma rays has been found to be 1.03 ± 0.05 for LiF-TLD (Harshaw) in our possession. The result stengthens the contention that the relative TL response of LiF-TLD can be essentially independent of energy. Further experiments are necessary to determine the material or experimental parameters which may lead to relative TL response significantly different from unity as previously reported in some experimental investigations.

  19. Development of simulated catalyst aging technique with athabasca bitumen

    SciTech Connect

    Kriz, J.F.; Ternan, M.

    1980-01-01

    The deactivation of Harshaw 0603T (3% CoO, 12% MoO) catalyst was tested with Athabasca bitumen in a modified version of previously described equipment for simulating catalyst aging. Catalyst aging was evaluated by the increase in product density and sulfur level. The deactivation proceeded in the same pattern but 30 times more rapidly at 495/sup 0/C and 5/hr liquid volumetric space velocity (simulation of aging conditions) than at 450/sup 0/C and 1/hr liquid volumetric space velocity (actual aging).

  20. Evaluation of a linear position sensitive neutron detector for powder spectroscopy

    NASA Astrophysics Data System (ADS)

    Chang, I.-Ping; Nunes, A. C.

    1982-09-01

    A one meter long position sensitive detector was acquired from Harshaw Corp. for a small angle neutron camera operated by the University of Rhode Island at the 2 MW reactor of the Rhode Island Nuclear Science Center. In the course of testing the detector system, to determine linearity, resolution, stability and efficiency, it was employed in a powder spectrometer. Once geometrical effects are properly taken care of, it appears that the present detector, though not optimized for powder diffraction, permits collection of data essentially equivalent to that taken with the original step scanned detector though 15 times faster.

  1. Evaluation of commercially available TLD readers

    NASA Astrophysics Data System (ADS)

    Gulbin, J.; Deplanque, G.

    1981-10-01

    The performance of two commercially available thermoluminescence bulb dosimetry systems, the Victoreen 2810 Ultra Sensitive TLD Reader and the Harshaw Model 2000P Bulb Dosimetry System, was investigaed. Of primary interest was the reliability of the instruments at an exposure range typically encountered in environmental radiation when monitoring on a monthly basis, i.e., approx. 10 mR. Uniformity, linearity, and reproducibility test results are reported. The two systems found to perform comparably well as bulb readers. Evaluation of the dual capability of the Victoreen 2810 as a chip reader is also described.

  2. Large enhancement of TLD-100 sensitivity by irradiation in a reactor core

    NASA Astrophysics Data System (ADS)

    How, Mooi Lau; Ah, Auu Gui; Harasawa, Susumu

    1986-09-01

    Irradiation of Harshaw TLD-100 chips by a thermal neutron fluence of about 10 16 n cm -2 in a reactor has caused an increase of their thermoluminescence output by a factor of about 8000 times. The increase is more or less proportional to the thermal neutron fluence, at least up to 10 16 n th cm -2. The irradiated TLDs are stable in their thermoluminescence output. As the glow curves before and after irradiation are similar, the original number of luminescence centres seems to have been increased by this irradiation. As a result, these TLD's are much more sensitive than even the most sensitive TLD presently available in the market.

  3. Thermoluminescence decay and emission spectra of some γ-irradiated alkali fluorides

    NASA Astrophysics Data System (ADS)

    Khedekar, Atmaram Vishnu; Ramani, Ramaseshan; Sardesai, Suresh Shamrao; Kalkar, Chandrakant Dattatraya

    1981-06-01

    The room temperature thermoluminescence (RTL) decay from γ-irradiated LiF single crystal (Harshaw), NaF and KF powders (40-60 mesh) were studied as a function of the gamma radiation dose. The total luminescence reaches a maximum for a particular dose depending on the nature of the crystal. The emission spectra for LiF, NaF and KF showed one, two and three emission bands, respectively, in the range 375 to 700 nm. The RTL disappears at higher doses for these fluorides. The results are explained on the basis of postulated metastable energy level.

  4. Evaluation of a linear position sensitive neutron detector for powder spectroscopy

    SciTech Connect

    Chang, I.P.; Nunes, A.C.

    1982-01-01

    A one meter long position sensitive detector was acquired from Harshaw Corp. for a small angle neutron camera operated by the University of Rhode Island at the 2 MW reactor of the Rhode Island Nuclear Science Center. In the course of testing the detector system, to determine linearity, resolution, stability, and efficiency, it was employed in a powder spectrometer. Once geometrical effects are properly taken care of, it appears that the present detector, though not optimized for powder diffraction, permits collection of data essentially equivalent to that taken with the original step scanned detector though 15 times faster.

  5. Correction factors for the ISO rod phantom, a cylinder phantom, and the ICRU sphere for reference beta radiation fields of the BSS 2

    NASA Astrophysics Data System (ADS)

    Behrens, R.

    2015-03-01

    The International Organization for Standardization (ISO) requires in its standard ISO 6980 that beta reference radiation fields for radiation protection be calibrated in terms of absorbed dose to tissue at a depth of 0.07 mm in a slab phantom (30 cm x 30 cm x 15 cm). However, many beta dosemeters are ring dosemeters and are, therefore, irradiated on a rod phantom (1.9 cm in diameter and 30 cm long), or they are eye dosemeters possibly irradiated on a cylinder phantom (20 cm in diameter and 20 cm high), or area dosemeters irradiated free in air with the conventional quantity value (true value) being defined in a sphere (30 cm in diameter, made of ICRU tissue (International Commission on Radiation Units and Measurements)). Therefore, the correction factors for the conventional quantity value in the rod, the cylinder, and the sphere instead of the slab (all made of ICRU tissue) were calculated for the radiation fields of 147Pm, 85Kr, 90Sr/90Y, and, 106Ru/106Rh sources of the beta secondary standard BSS 2 developed at PTB. All correction factors were calculated for 0° up to 75° (in steps of 15°) radiation incidence. The results are ready for implementation in ISO 6980-3 and have recently been (partly) implemented in the software of the BSS 2.

  6. Some developments in neutron and charged particle dosimetry.

    PubMed

    Bos, Adrie J J; d'Errico, Francesco

    2006-01-01

    There is an increasing need for dosimetry of neutrons and charged particles. Increasing exposure levels are reported in the nuclear industry, deriving from more frequent in-service entries at commercial nuclear power plants, and from increased plant decommissioning and refurbishment activities. Another need stems from the compliance with requirements of the regulations and standards. The European Council directive 96/29 requires dosimetric precautions if the effective dose exceeds 1 mSv a(-1). On average, aircrew members exceed this value. Further, there is a trend of increasing use of charged particles in radiotherapy. The present situation is that we have reasonably good photon dosemeters, but neutron and charged particle dosemeters are still in need of improvements. This work highlights some of the developments in this field. It is mainly concentrated on some developments in passive dosimetry, in particular thermally and optically stimulated luminescent detectors, indicating the direction of ongoing research. It shows that passive dosemeters are still a very active field. Active dosemeters will not be discussed with the exception of new developments in microdosimetric measurements [new types of tissue equivalent proportional counters (TEPCs)]. The TEPC is unique in its ability to provide a simultaneous determination of neutron / charged particle / gamma ray doses, or dose equivalents using a single detector. PMID:16987918

  7. Dose measurements in space by the Hungarian Pille TLD system.

    PubMed

    Apathy, I; Deme, S; Feher, I; Akatov, Y A; Reitz, G; Arkhanguelski, V V

    2002-10-01

    Exposure of crew, equipment, and experiments to the ambient space radiation environment in low Earth orbit poses one of the most significant problems to long-term space habitation. Accurate dose measurement has become increasingly important during the assembly (extravehicular activity (EVA)) and operation of space stations such as on Space Station Mir. Passive integrating detector systems such as thermoluminescent dosemeters (TLDs) are commonly used for dosimetry mapping and personal dosimetry on space vehicles. The well-known advantages of passive detector systems are their independence of power supply, small dimensions, high sensitivity, good stability, wide measuring range, resistance to environmental effects, and relatively low cost. Nevertheless, they have the general disadvantage that for evaluation purposes they need a laboratory or large--in mass and power consumption--terrestrial equipment, and consequently they cannot provide time-resolved dose data during long-term space flights. KFKI Atomic Energy Research Institute (KFKI AEKI) has developed and manufactured a series of thermoluminescent dosemeter systems for measuring cosmic radiation doses in the 10 microGy to 10 Gy range, consisting of a set of bulb dosemeters and a compact, self-contained, TLD reader suitable for on-board evaluation of the dosemeters. By means of such a system, highly accurate measurements were carried out on board the Salyut-6, -7 and Mir Space Stations as well as on the Space Shuttle. A detailed description of the system is given and the comprehensive results of these measurements are summarised. PMID:12440428

  8. Personal dose equivalent angular response factors for photons with energies up to 1 GeV.

    PubMed

    Veinot, K G

    2013-04-01

    When performing personal dosemeter calibrations, the dosemeters are typically irradiated while mounted on slab-type phantoms and oriented facing the source. Performance testing standards or intercomparison studies may also specify various rotational angles to test the response of the dosemeter and associated algorithm as this rotation introduces changes in the quantity of delivered dose. Correction factors for rotational effects are available, but many have not been updated in recent years and were typically calculated using the kerma approximation. The personal dose equivalent, Hp(d), is the quantity recommended by the International Commission on Radiation Units and Measurements to be used as an approximation of the protection quantity effective dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body, but typically the location of interest is the trunk where personal dosemeters are worn and in this instance a suitable approximation is a 30 cm 30 cm 15 cm slab-type phantom. In this work personal dose equivalent conversion coefficients for photons with energies up to 1 GeV have been calculated for depths of 0.007, 0.3 and 1.0 cm in the slab phantom for rotational angles ranging from 15 to 75. Angular response factors have been determined by comparing the conversion coefficients for each angle and energy to those reported in an earlier work for a non-rotational (e.g. perpendicular to the phantom face) geometry. The angular response factors were determined for discrete angles, but fits of the factors are provided. PMID:22914333

  9. Fire testing of bare uranium hexafluoride cylinders

    SciTech Connect

    Pryor, W.A.

    1991-12-31

    In 1965, the Oak Ridge Gaseous Diffusion Plant (ORGDP), now the K-25 Site, conducted a series of tests in which bare cylinders of uranium hexafluoride (UF{sub 6}) were exposed to engulfing oil fires for the US Atomic Energy Commission (AEC), now the US Department of Energy (DOE). The tests are described and the results, conclusions, and observations are presented. Two each of the following types of cylinders were tested: 3.5-in.-diam {times} 7.5-in.-long cylinders of Monel (Harshaw), 5.0-in.-diam {times} x 30-in.-long cylinders of Monel, and 8-in.-diam {times} 48-in.-long cylinders of nickel. The cylinders were filled approximately to the standard UF{sub 6} fill limits of 5, 55, and 250 lb, respectively, with a U-235 content of 0.22%. The 5-in.- and 8-in.-diam cylinders were tested individually with and without their metal valve covers. For the 3.5-in.-diam Harshaw cylinders and the 5.0-in.-diam cylinder without a valve cover, the valves failed and UF{sub 6} was released. The remaining 6 cylinders ruptured explosively in time intervals ranging from about 8.5 to 11 min.

  10. Fire testing of bare uranium hexafluoride cylinders

    SciTech Connect

    Pryor, W.A.

    1991-12-31

    In 1965, the Oak Ridge Gaseous Diffusion Plant (ORGDP), now the K-25 Site, conducted a series of tests in which bare cylinders of uranium hexafluoride (UF{sub 6}) were exposed to engulfing oil fires for the US Atomic Energy Commission (AEC), now the US Department of Energy (DOE). The tests are described and the results, conclusions, and observations are presented. Two each of the following types of cylinders were tested: 3.5-in.-diam {times} 7.5-in.-long cylinders of Monel (Harshaw), 5.0-in.-diam {times} 30-in.-long cylinders of Monel, and 8-in.-diam {times} 48-in.-long cylinders of nickel. The cylinders were filled approximately to the standard UF{sub 6} fill limits of 5, 55, and 250 lb, respectively, with a U-235 content of 0.22%. The 5-in.- and 8-in.-diam cylinders were tested individually with and without their metal valve covers. For the 3.5-in.-diam Harshaw cylinders and the 5.0-in.-diam cylinder without a valve cover the valves failed and UF{sub 6} was released. The remaining cylinders ruptured explosively in time intervals ranging from about 8.5 to 11 min.

  11. Radiation measurements inside the CDF detector

    SciTech Connect

    Yarema, R.J.

    1989-07-20

    During the last CDF experimental period from 6/88 to 6/1/89, radiation measurements were made inside the detector on or near the beampipe using various types of monitors. The purpose of the tests was to help predict the radiation levels for future electronics which must be located close to the interaction area. The results from two different types of monitors, PIN diodes and TLD's are reported in this paper. The TLD's (Harshaw/Filtrol type 700) are sensitive to x-rays, gammas, alphas, electrons, and protons. They are calibrated against a cesium source and corrected for nonlinear effects at higher radiation levels. The PIN diodes (Harshaw/Filtrol type DN-156) are sensitive only to neutrons. The devices are calibrated for 1 MeV neutrons and require correction factors for neutrons at other energy levels. All of the monitors were placed just outside of the VTPC, but still inside the CDF magnetic field. The monitors were located 68 inches from the center of the interaction region. The beam pipe is 2 inches in diameter. Therefore the closest monitoring points were on the beampipe or 1 inch from the beam. 5 figs., 2 tabs.

  12. Hydrodeoxygenation of phenolic components of wood-derived oil

    SciTech Connect

    Elliott, D.C.

    1983-03-01

    Hydrotreatment of wood-derived oil to remove phenolic oxygen is a potential upgrading step by which such materials can be rendered compatible with current petroleum refining technology and converted to a diesel equivalent. Accordingly, the hydrodeoxygenation of model phenols and wood derived oil was studied in a batch reactor. Using phenol, a number of commercial catalysts were evaluated for performance and stability at reaction temperatures from 300 to 425/sup 0/C and hydrogen pressures from 900 to 2050 psig. Product yields and analysis indicate the most efficient catalysts to be Ni (Ni 1404, Harshaw) and presulfided Co-Mo (CoMo 0402, Harshaw), based on yields of benzene and cyclohexane. Due to complications caused by the introduction of sulfur into the system, the Ni catalyst may be preferred. Alkyl phenols, napthol and guiacol were hydrotreated at 400/sup 0/C and 2000 psig using an unsulfided Co-Mo catalyst. In addition to the corresponding alkylated aromatic and saturated cycloalkanes, significant yields of scrambled aromatic product, formed by dealkylation and methyl migration were observed. Guiacol hydrotreatment is complex, there being significant polymerization and dimerization: pyrolysis, not catalystic hydrodeoxygenation is the major reaction path. Wood-derived oils were partially deoxygenated and somewhat upgraded by hydrotreatment using Ni and sulfided Co-Mo catalysts.

  13. Study of the improvement of TLD cards for personal neutron dosimetry

    NASA Astrophysics Data System (ADS)

    Rabie, N.; Hassan, G. M.; El-Sersy, A. R.; Ezzat, M.

    In this work, personal thermoluminescence dosimeter (TLD) cards type of GN-6770 (holder type 8806) from Harshaw were used for personal neutron dosimetry. The response of the dosimeters has been determined in terms of the personal absorbed dose and personal dose equivalent for different neutron energy components, based on the recommendations of ICRP-60 and ICRU-49. Neutron irradiation was performed using a 5 mCi Am-Be neutron source. The TLD reader, type Harshaw 6600, was installed and calibrated for accurate neutron doses equivalent to gamma-ray doses. It was found that fast neutron doses measured by TLD (badges or cards) are in agreement with those measured by neutron TE (tissue equivalent gas) ionization chambers and neutron monitors. Thermal neutron doses measured by TLD cards were overestimated when compared with those measured by neutron monitors. Additional Cd was used to reduce thermal neutron doses to be in agreement with actual thermal doses. Other configurations for TLD crystals are also suggested for accurate thermal neutron dose measurements.

  14. Catalytic coal liquefaction. Quarterly report, January-March 1981

    SciTech Connect

    Weller, S. W.

    1981-01-01

    A new tubing bomb micro reactor has been designed, constructed, and tested. It is suitable for catalyst comparisons in experiments of widely differing nature. The reactor is capable of initial pressurization with H/sub 2/, heating, pressure monitoring during a run, and G.C. analysis of gaseous products. An extensive series of runs has been completed on the hydrotreating of 1-methylnaphthalene as a multifunctional catalyst screening test at 500/sup 0/C. Six Co/Mo/Al/sub 2/O/sub 3/ catalysts from four suppliers have been tested (after presulfiding), along with a comparison run with stannous chloride. At a catalyst level of 0.5 wt.%, the rank-ordering of activity for ring hydrogenation (RHG) was Cyanamid HDS-1442B>AmocatlA>Harshaw 0402T approx. AkzoPA-23924>Amocat1B>Akzo77-RAM-3. Ring hydrocracking (RHC) activity decreased in the order Amocat 1A approx. Amocat1B>Akzo PA-23924>Harshaw 0402T>Akzo 77-RAM-3 approx. Cyanamid HDS1442B. Hydrodemethylation (HDM) is almost unaffected by Co/Mo/Al/sub 2/O/sub 3/ catalysts. At 500/sup 0/C the extent of RHC and HDM is much greater than at 450/sup 0/C, but the extent of RHG is much less.

  15. Catalytic methods for improved coal liquefaction and hydrotreating: Quarterly report No. 6 for the period December 23, 1986 through March 22, 1987

    SciTech Connect

    Hirschon, A.S.; Laine, R.M.; Wilson, R.B. Jr.

    1987-04-01

    During this quarter we synthesized two new ruthenium catalysts. The first catalyst, Ru/sub 3/(CO)/sub 12/ supported on alumina, Ru(OM), was prepared to compare the reactivity of supported ruthenium carbonyl with that of bulk ruthenium, and with the RuMo(OM) catalyst prepared last quarter. The second catalyst was a RuCoMo catalyst prepared from the promotion of sulfided Harshaw CoMo with ruthenium trichloride, rather than with ruthenium carbonyl, which was used in previous preparations. We found that the ruthenium supported on alumina, Ru(OM), had the same activity and selectivity as bulk ruthenium, and was totally poisoned by hydrogen sulfide, as was the bulk metal. We also found that the RuCoMo prepared by ruthenium trichloride promotion had a similar activity and selectivity as the RuCoMo catalyst prepared by ruthenium carbonyl impregnation. Comparisons of the CoMo and RuCoMo catalysts were made on the HDN of decahydroquinoline (DHQ). We found in both cases the HDN product was almost exclusively propylcyclohexane, showing that the formation of propylbenzene during the HDN of quinoline must come from propylaniline or benzotetrahydroquinoline. We also compared the surface areas and pore sizes of the Harshaw CoMo and promoted RuCoMo catalysts and found them very similar. This quarter we presented a summary of our work on our use of organometallic precursors and promoted RuCoMo catalysts at the Denver ACS meeting. 4 refs.

  16. Optical absorption and thermoluminescence in LiF TLD-100

    NASA Astrophysics Data System (ADS)

    Caldas, Linda V. E.; Mayhugh, Michael R.; Stoebe, Thomas G.

    1983-06-01

    The thermoluminescent (TL) properties of many LiF samples have demonstrated a strong influence on trace impurities and impurity content on the TL process. Hence, the general validity of any particular model must be tested against its applicability in a standard material such as Harshaw LiF (TLD-100). In this paper the validity of the use of Harshaw LiF(54) by Mayhugh et al. in their model development for the TL process in LiF is demonstrated by comparing the TL and optical properties of LiF(54) with TLD-100. The specific properties of optical absorption bands at 310 and 380 nm, the F band near 250 nm, and the Z3 band near 225 nm are intercompared with observed TL peaks in both materials. Both the gamma and uv-exposure behavior of the Z3 center demonstrates a direct relationship between Z3 and TL peak 10, while no direct conversion between Z3 and the 310-nm band is observed in TLD-100. These results do not support recent models identifying Z3 with TL peak 6 and Z2 with the 310-nm band (and TL peak 5); this is probably due to differences in purity and defect state in the LiF samples used by other investigators, emphasizing the need for standardization of materials in this system.

  17. New catalysts for coal-liquid upgrading. Quarterly report, March 1, 1983-May 31, 1983. [More generally various metallophthalocyanines

    SciTech Connect

    Boucher, L.J.

    1983-01-01

    The conversion of quinaldine was compared to that of quinoline using the commercial catalysts: NiMo oxide/Al/sub 2/O/sub 3/ (HT-500E, %NiO = 3.5, %MoO/sub 3/ = 15.5, surface area 200 m/sup 2//g), NiW/Al/sub 2/O/sub 3/ (Harshaw Ni 4301E; %Ni = 6, %W = 19 surface area = 230 m/sup 2//g) CoMo oxide/Al/sub 2/O/sub 3/ (Harshaw CoMo-0603; %CoO = 3, %MoO/sub 3/ = 12, surface area = 166 m/sup 2//g. The rates of hydrogenation of several nitrogen containing heterocycles have been measured at 1000 psi H/sub 2/ pressure and 250 to 350/sup 0/C using (Co(PC)) supported on silica, alumina, silica-alumina. Although our initial reports were to the contrary, present results are consistent with a first order hydrogenation of substrate. For the hydrogenation of quinoline the support influences the rate to a small extent. The various substrates undergo hydrogenation at different rats.

  18. The high dose response and functional capability of the DT-702/Pd lithium fluoride thermoluminescent dosimeter.

    PubMed

    Lawlor, Tyler M; Talmadge, Molly D; Murray, Mark M; Nelson, Martin E; Mueller, Andrew C; Romanyukha, Alexander A; Fairchild, Gregory R; Grypp, Matthew D; Williams, Anthony S

    2015-05-01

    The United States Navy monitors the dose its radiation workers receive using the DT-702/PD thermoluminescent dosimeter, which consists of the Harshaw 8840 holder and the four-element Harshaw 8841 card. There were two main objectives of this research. In the first objective, the dosimeters were exposed to 100 Gy using electron and x-ray beams and found to respond approximately 30-40% lower than the delivered dose. No significant effect on the under-response was found when dose rate, radiation type, dosimeter position on the phantom, and dosimeter material were varied or when the card was irradiated while enclosed in its holder. Since the current naval policy is to remove from occupational use any thermoluminescent dosimeter with an accumulated deep dose equivalent of 0.05 Sv or greater, the functionality of the dosimeter was also investigated at deep dose equivalents of 0.05, 0.15, and 0.25 Sv using 60Co and 137Cs sources as the second main objective. All dosimeters were annealed following exposure and then exposed to 5.0 mSv from a 90Sr source. In all cases, the dosimeters responded within 3% of the delivered dose, indicating that the dosimeters remained functional as defined by naval dosimetry requirements. However, the anneal time required to clear the thermoluminescent dosimeter's reading was found to increase approximately as the cube root with the delivered dose. PMID:25811149

  19. Evaluating the performance of the Harshaw™ DXTRAD LiF:Mg,Cu,P finger ring with two different thickness filters.

    PubMed

    Baker, S T; Roberts, G H; Gilvin, P J

    2011-03-01

    Amongst the dosemeters offered by the Health Protection Agency (HPA) Personal Dosimetry Service are finger rings, which use the Harshaw™ DXTRAD element. This paper describes restricted-type testing carried out by HPA on the previously untried combination of the LiF:Mg,Cu,P material and a thicker filter (42 mg cm(-2)). The tests were based on ISO 12794 [International Organization for Standardization. ISO 12794:2000 nuclear energy--radiation protection--individual thermoluminescence dosemeters for the extremities and eyes. ISO (2000)] and included energy and angle dependence of response for photons. The conclusion was, for photon dosimetry applications the thicker filter is acceptable for use in the HPA service. PMID:21212080

  20. Surface dose measurement in patients and physicians and effective dose estimation in patients during uterine artery embolisation.

    PubMed

    Nishizawa, K; Masuda, Y; Morinaga, K; Suzuki, S; Kikuyama, S; Yoshida, T; Ohno, Mari; Akahane, K; Iwai, K

    2008-01-01

    Surface dose monitoring in patients and physicians during 29 uterine artery embolisation (UAE) procedures was performed using photoluminescence dosemeters and thermo-luminescence dosemeters. Organ or tissue doses were measured with an anthropomorphic phantom using UAE exposure conditions averaged from the 29 cases, and effective doses were estimated for the patient. Entrance surface dose of the patients at the maximum dose position ranged from 121.5 to 1650 mGy. Estimated doses ranged from 3.16 to 43 mGy for the ovary and from 3.8 to 51.8 mGy for the uterus. The effective dose was 1.09-14.8 mSv. Monitored doses on the body surface of physicians were relatively high in the upper arm (5.41+/-1.52 to 163+/-17.25 microGy) and the hand and fingers (0.85+/-1.18 to 222+/-16.4 microGy). PMID:18337296

  1. Dosimetric properties of a radiochromic gel detector for diagnostic X-rays

    NASA Astrophysics Data System (ADS)

    Bero, M. A.

    2007-09-01

    The gel dosimetry method was found to be capable of addressing complicated issues related to dose measurements particularly in modern sophisticated radiotherapy applications. The Ferrous-sulphate Xylenol-orange and Gelatin (FXG) radiochromic gel dosemeter is one of the systems used for such applications. Some chemical dosemeters show different responses for low- and medium-energy X-rays in comparison with high-energy γ-photons. The energy and dose rate dependence of the FXG dose response was examined. In addition to the detector response, other important dosimetric properties of the system were investigated for different X-ray beam qualities with tube voltages in the range 100-300 kV. An orthovoltage X-ray therapy unit was used to irradiate standard sized samples of FXG from different batches for radiation doses in the range 0-20 Gy.

  2. Characterisation of the TAPIRO BNCT epithermal facility.

    PubMed

    Burn, K W; Colli, V; Curzio, G; d'Errico, F; Gambarini, G; Rosi, G; Scolari, L

    2004-01-01

    A collimated epithermal beam for boron neutron capture therapy (BNCT) research has been designed and built at the TAPIRO fast research reactor. A complete experimental characterisation of the radiation field in the irradiation chamber has been performed, to verify agreement with IAEA requirements. Slow neutron fluxes have been measured by means of an activation technique and with thermoluminescent detectors (TLDs). The fast neutron dose has been determined with gel dosemeters, while the fast neutron spectrum has been acquired by means of a neutron spectrometer based on superheated drop detectors. The gamma-dose has been measured with gel dosemeters and TLDs. For an independent verification of the experimental results, fluxes, doses and neutron spectra have been calculated with Monte Carlo simulations using the codes MCNP4B and MCNPX_2.1.5 with the direct statistical approach (DSA). The results obtained confirm that the epithermal beams achievable at TAPIRO are of suitable quality for BNCT purposes. PMID:15353724

  3. A practical method to evaluate radiofrequency exposure of mast workers.

    PubMed

    Alanko, Tommi; Hietanen, Maila

    2008-01-01

    Assessment of occupational exposure to radiofrequency (RF) fields in telecommunication transmitter masts is a challenging task. For conventional field strength measurements using manually operated instruments, it is difficult to document the locations of measurements while climbing up a mast. Logging RF dosemeters worn by the workers, on the other hand, do not give any information about the location of the exposure. In this study, a practical method was developed and applied to assess mast workers' exposure to RF fields and the corresponding location. This method uses a logging dosemeter for personal RF exposure evaluation and two logging barometers to determine the corresponding height of the worker's position on the mast. The procedure is not intended to be used for compliance assessments, but to indicate locations where stricter assessments are needed. The applicability of the method is demonstrated by making measurements in a TV and radio transmitting mast. PMID:19054796

  4. Implementation of an electronic personal dosimetry system (EPD) at Oldbury-on-Severn power station.

    PubMed

    Clarke, P W; Weeks, A R

    2001-03-01

    This article presents the implementation of an electronic personal dosemeter (EPD) as a film badge replacement at Oldbury-on-Severn power station, which is the first major site to use an approval issued by the UK Health and Safety Executive (HSE) for dose measurement by an EPD. The practicalities and history behind the introduction of an EPD for personal dosimetry are described. PMID:11281529

  5. Individual monitoring based on magnesium borate.

    PubMed

    Proki?, Mirjana

    2007-01-01

    Valuable features of magnesium borate sintered solid thermoluminescence dosemeters (TLDs), such as near tissue- equivalence, high sensitivity, and good performances for X, gamma, beta and neutron dosimetry, were developed and produced by the Institute of Nuclear Sciences, Vinca. These features form the basis for using this type of TLDs successfully for legal personal dosimetry control in Serbia for the past 27 y. The dosimetric properties of this TL material are presented in this study. PMID:16980707

  6. Pacific Northwest Laboratory annual report for 1984 to the DOE Office of the Assistant Secretary for Policy, Safety, and Environment. Part 5. Overview and assessment

    SciTech Connect

    Bair, W.J.

    1985-02-01

    Research conducted in 1984 is briefly described. Research areas include: (1) uncertainties in modeling source/receptor relations for acidic deposition; (2) health physics support and assistance to the DOE; (3) technical guidelines for radiological calibrations; (4) personnel neutron dosemeter evaluation and upgrade program; (5) beta measurement evaluation and upgrade; (6) accreditation program for occupational exposure measurements; (7) assurance program for Remedial Action; (8) environmental protection support and assistance; (9) hazardus waste risk assessment; and (10) radiation policy studies. (ACR)

  7. A method to minimise the fading effects of LiF:Mg,Ti (TLD-600 and TLD-700) using a pre-heat technique.

    PubMed

    Lee, YoungJu; Won, Yuho; Kang, Kidoo

    2015-04-01

    Passive integrating dosemeters [thermoluminescent dosimeter (TLD) and optically stimulated luminescence (OSL)] are the only legally permitted individual dosemeters for occupational external radiation exposure monitoring in Korea. Also its maximum issuing cycle does not exceed 3 months, and the Korean regulations require personal dosemeters for official assessment of external radiation exposure to be issued by an approved or rather an accredited dosimetry service according to ISO/IEC 17025. KHNP (Korea Hydro & Nuclear Power, LTD), a unique operating company of nuclear power plants (NPPs) in Korea, currently has a plan to extend a TLD issuing cycle from 1 to 3 months under the authors' fading error criteria, 10%. The authors have performed a feasibility study that minimises post-irradiation fading effects within their maximum reading cycle employing pre-heating technique. They repeatedly performed irradiation/reading a bare TLD chip to determine optimum pre-heating conditions by analysing each glow curve. The optimum reading conditions within the maximum reading cycle of 3 months were decided: a pre-heating temperature of 165C, a pre-heating time of 9 s, a heating rate of 25C s(-1), a reading temperature of 300C and an acquisition time of 10 s. The fading result of TLD-600 and TLD-700 carried by newly developed time temperature profile (TTP) showed a much smaller fading effect than that of current TTP. The result showed that the fading error due to a developed TTP resulted in a ?5% signal loss, whereas a current TTP caused a ?15% loss. The authors also carried out a legal performance test on newly developed TTP to confirm its possibility as an official dosemeter. The legal performance tests that applied the developed TTP satisfied the criteria for all the test categories. PMID:25301971

  8. On the interpretation and use of neutron calibration coefficients.

    PubMed

    Schwartz, R B; McDonald, J C

    2003-01-01

    Calibration laboratories provide measurement services that include determining the calibration coefficients for neutron survey meters and personal dosemeters. While there are numerous documents dealing with the procedures for calibration of neutron measuring devices, the purpose of this paper is to clarify the use of the particular dose equivalent conversion coefficients used at the National Institute of Standards and Technology and the Pacific Northwest National Laboratory for these calibrations. PMID:14756185

  9. Monitoring the eye lens: which dose quantity is adequate?

    NASA Astrophysics Data System (ADS)

    Behrens, R.; Dietze, G.

    2010-07-01

    Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. The question of which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens arises from this situation. While in many countries dosemeters calibrated in terms of the dose equivalent quantity Hp(0.07) have been seen as being adequate for monitoring the dose to the eye lens, this might be questionable in the case of reduced dose limits and, thus, it may become necessary to use the dose equivalent quantity Hp(3) for this purpose. To discuss this question, the dose conversion coefficients for the equivalent dose of the eye lens (in the following eye lens dose) were determined for realistic photon and beta radiation fields and compared with the values of the corresponding conversion coefficients for the different operational quantities. The values obtained lead to the following conclusions: in radiation fields where most of the dose comes from photons, especially x-rays, it is appropriate to use dosemeters calibrated in terms of Hp(0.07) on a slab phantom, while in other radiation fields (dominated by beta radiation or unknown contributions of photon and beta radiation) dosemeters calibrated in terms of Hp(3) on a slab phantom should be used. As an alternative, dosemeters calibrated in terms of Hp(0.07) on a slab phantom could also be used; however, in radiation fields containing beta radiation with the end point energy near 1 MeV, an overestimation of the eye lens dose by up to a factor of 550 is possible.

  10. Extra dose due to extravehicular activity during the NASA4 mission measured by an on-board TLD system.

    PubMed

    Deme, S; Apathy, I; Hejja, I; Lang, E; Feher, I

    1999-01-01

    A microprocessor-controlled on-board TLD system, 'Pille'96', was used during the NASA4 (1997) mission to monitor the cosmic radiation dose inside the Mir Space Station and to measure the extra dose to two astronauts in the course of their extravehicular activity (EVA). For the EVA dose measurements, CaSO4:Dy bulb dosemeters were located in specially designed pockets of the ORLAN spacesuits. During an EVA lasting 6 h, the dose ratio inside and outside Mir was measured. During the EVA, Mir crossed the South Atlantic Anomaly (SAA) three times. Taking into account the influence of these three crossings the mean EVA/internal dose rate ratio was 3.2. Internal dose mapping using CaSO4:Dy dosemeters gave mean dose rates ranging from 9.3 to 18.3 microGy h-1 at locations where the shielding effect was not the same. Evaluation results of the high temperature region of LiF dosemeters are given to estimate the mean LET. PMID:11542227

  11. Characterisation of OSL and OSLN droplets for dosimetry.

    PubMed

    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. PMID:24381203

  12. Characterisation of neutron fields: challenges in assessing the directional distribution.

    PubMed

    Cauwels, Vanessa; Vanhavere, Filip; Reginatto, Marcel

    2014-10-01

    The SCK·CEN has carried out neutron field characterisation campaigns at several nuclear reactors. The main goal of these measurement campaigns was to evaluate the performance of different neutron personal dosemeters. To be able to evaluate the performance of neutron personal dosemeters in terms of Hp(10), knowledge of the directional distribution is indispensable. This distribution was estimated by placing several personal dosemeters on all six sides of a slab phantom. The interpretation and conversion of this information into a reliable value for Hp(10) requires great care. The data were analysed using three methods. In the first approach, a linear interpolation was performed on three perpendicular axes. In the other two approaches, an icosahedron was used to model the angle of incidence of the neutrons and a linear interpolation or a Bayesian analysis was performed. This study describes the limitations and advantages of each of these methods and provides recommendations for their use to estimate the personal dose equivalent Hp(10) for neutron dosimetry. PMID:24966340

  13. Low-energy x-ray dosimetry studies (7 to 17.5 keV) with synchroton radiation

    SciTech Connect

    Ipe, N.E.; Bellamy, H.; Flood, J.R.

    1995-06-01

    Unique properties of synchrotron radiation (SR), such as its high intensity, brightness, polarization, and broad spectral distribution (extending from x-ray to infra-red wavelengths) make it an attractive light source for numerous experiments. As SR facilities are rapidly being built all over the world, they introduce the need for low-energy x-ray dosemeters because of the potential radiation exposure to experimenters. However, they also provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory are described. Lithium fluoride TLDs (TLD-100) of varying thicknesses (0.015 to 0.08 cm) were exposed free in air to monochromatic x-rays (7 to 17.5 keV). These exposures were monitored with ionization chambers. The response (nC/Gy) was found to increase with increasing TLD thickness and with increasing beam energy. A steeper increase in response with increasing energy was observed with the thicker TLDs. The responses at 7 and 17.5 keV were within a factor of 2.3 and 5.2 for the 0.015 and 0.08 cm-thick TLDs, respectively. The effects of narrow (beam size smaller than the dosemeter) and broad (beam size larger than the dosemeter) beams on the response of the TLDs are also reported.

  14. Bonner sphere neutron spectrometry at spent fuel casks

    NASA Astrophysics Data System (ADS)

    Rimpler, Arndt

    2002-01-01

    For transport and interim storage of spent fuel elements from power reactors and vitrified highly active waste (HAW) from reprocessing, various types of casks are used. The radiation exposure of the personnel during transportation and storage of these casks is caused by mixed photon-neutron fields and, frequently, the neutron dose is predominant. In operational radiation protection, survey meters and even personal dosemeters with imperfect energy dependence of the dose-equivalent response are used, i.e. the fluence response of the devices does not match the fluence-to-dose equivalent conversion function. In order to achieve more accurate dosimetric information and to investigate the performance of dosemeters, spectrometric investigations of the neutron fields are necessary. Therefore, fluence spectra and dose rates were measured by means of a simple portable Bonner multisphere spectrometer (BSS). The paper describes briefly the experimental set-up and evaluation procedure. Measured spectra for different locations, types of casks and inventory are discussed. The spectra provide a basis to determine dose rates and other integral quantities with higher accuracy and for choosing suitable area monitors, respectively, to establish correction factors applied to the dosemeter reading.

  15. Determination of personal dose equivalents in accelerator radiation fields.

    PubMed

    McDonald, J C

    2001-01-01

    Values for the dose equivalent are required for radiation protection purposes, but determination of such values can be quite difficult for high energy radiations. The accurate determination of personal dose equivalents in accelerator radiation fields requires the propel use of appropriate radiological quantities and units, knowledge of the dose equivalent response of the personal dosemeters used, measurement or calculation of the fluence spectrum in the workplace and the fluence spectrum of the reference radiation used to calibrate the dosemeters, in addition to knowledge of the appropriate fluence-to-dose equivalent conversion coefficients. This information can then be used to select the appropriate dosemeters, set up the optimum calibration conditions, or to establish correction factors that account for differences in the calibration and workplace fluence spectra. High energy neutrons account for a significant fraction of the dose equivalent received by workers at accelerator facilities, and this work discusses the procedures and methods needed to determine dose equivalent produced by neutrons in the vicinity of high energy particle accclerators. PMID:11843090

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

    PubMed

    d'Errico, F; Bartlett, D; Bolognese-Milsztajn, T; Boschung, M; Coeck, M; Curzio, G; Fiechtner, A; Kyllnen, 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. PMID:17522043

  17. Studies involving high temperature desulfurization/regeneration reactions of metal oxides for fuel cell developments. Project status report, February 1983

    SciTech Connect

    Not Available

    1983-03-10

    In the current reporting period, we carried out desulfurization/regeneration tests of the CuO/ZnO sorbent mixed with sand in the fluidized bed reactor. Very high sulfur capacities were observed which decreased on subsequent cycles. Because of low temperature reduction (250/sup 0/) and desulfurization (500/sup 0/C), no zinc loss from the bed was observed. A blank run with sand will be carried out to observe the reactivity of mineral salts in sand with H/sub 2/S. We also carried out the experiment of three different ZnO sorbents (U.C., Harshaw and Strem) diluted with alumina in quartz lined packed bed reactor for the modeling work.

  18. Investigation of basic characteristics of laser heating in thermoluminescence and of laser-stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Braunlich, P. F.

    1985-03-01

    Experimental and computational methods are presented for the complete characterization of the thermoluminescence response obtained from semi-infinite slabs of thermoluminescent phosphors upon exposure to localized Gaussian laser heating beams. A number of different phosphor configurations are described as examples. These include LiF:Mg,Ti (TLD-100, Harshaw Chemical Corporation) in form of chips, which are widely used in the dosimetry of ionizing radiation, and thin layer dosimeters prepared either as self-supporting films of powder in a polyimide matrix, or on substrates of LiF single crystals or borosilicate glass. It is demonstrated that all relevant optical and thermal properties of the dosimeters can be determined by these methods and that, based on this knowledge, the expected thermoluminescence response of a given configuration can be simulated as a function of a number of experimental parameters.

  19. Heating Rate Effects on Thermoluminescence of BaSO4:Eu+PTFE Prepared at Inin-Mexico

    NASA Astrophysics Data System (ADS)

    Gonzalez, P. R.; Furetta, C.; Cruz-Zaragoza, E.; Azorín, J.

    In this work, we show the influence of heating rate (H.R.) on the thermoluminescence (TL) signal of BaSO4 activated by Eu ions. The maximum temperature, the TL integral, the activation energy, the frequency factor and full width at half maximum of the TL glow-peak as a function of the H.R. were studied. The TL reading system used was a Harshaw TL reader model 4000, with constant H.R. in the range from 2 to 12 K/s. The irradiation dose was 0.1 Gy from 60Co in all cases. The kinetic parameters and their dependence on the H.R. were evaluated using the sequential quadratic programming glow curve deconvolution (SQPGCD). The experimental results showed that as the H.R. increases, the IM shifts to higher temperature; similar behavior of the kinetics parameters were obtained.

  20. Hydrogenation reactions of model titanium compounds under coal liquefaction conditions

    SciTech Connect

    Treblow, M.; Brown, F.R.; Spitler, C.A.

    1983-11-01

    Used catalyst and reactor deposits from a fixed-bed coal liquefaction unit show high concentrations of titanium and boron. The titanium was present as anatase, a titania polymorph. Hydrogenation reactions with and without catalyst were performed with model titanium and boron compounds under liquefaction conditions. The catalyst used was Harshaw 0402T 3% CoO - 15% MoO/sub 3/ on an alumina-silica support. Rutile remained unchanged by reactor conditions. In all other runs the titanium starting material, whether organic or inorganic in nature, converted to anatase. When the deposition of the reaction products was monitored, only that anatase derived from organic titanium compounds accumulated on and in the catalyst pellets to an appreciable extent.

  1. Evaluation of new and conventional thermoluminescent phosphors for environmental monitoring using automated thermoluminescent dosimeter readers

    SciTech Connect

    Rathbone, B.A.; Endres, A.W.; Antonio, E.J.

    1994-10-01

    In recent years, there has been considerable interest in a new generation of super-sensitive thermoluminescent (TL) phosphors for potential use in routine personnel and environmental monitoring. Two of these phosphors, {alpha}-Al{sub 2}O{sub 3}:C and LiF:Mg,Cu,P, are evaluated in this paper for selected characteristics relevant to environmental monitoring, along with two conventional phosphors widely used in environmental monitoring, LiF:Mg,Ti and CaF{sub 2}:Dy. The characteristics evaluated are light-induced fading, light-induced background, linearity and variability at low dose, and the minimum measurable dose. These characteristics were determined using an automated commercial dosimetry system (Harshaw System 8800) and routine processing protocols. Annealing and readout protocols for each phosphor were optimized for use in a large-scale environmental monitoring program.

  2. Analysis of read-out heating rate effects on the glow peaks of TLD-100 using WinGCF software

    NASA Astrophysics Data System (ADS)

    Bauk, Sabar; Hussin, Siti Fatimah; Alam, Md. Shah

    2016-01-01

    This study was done to analyze the effects of the read-out heating rate on the LiF:Mg,Ti (TLD-100) thermoluminescent dosimeters (TLD) glow peaks using WinGCF computer software. The TLDs were exposed to X-ray photons with a potential difference of 72 kVp and 200 mAs in air and were read-out using a Harshaw 3500 TLD reader. The TLDs were read-out using four read-out heating rates at 10, 7, 4 and 1 °C s-1. It was observed that lowering the heating rate could separate more glow peaks. The activation energy for peak 5 was found to be lower than that for peak 4. The peak maximum temperature and the integral value of the main peak decreased as the heating rate decreases.

  3. Laser stimulated thermoluminescence

    NASA Astrophysics Data System (ADS)

    Abtahi, A.; Bräunlich, P.; Kelly, P.; Gasiot, J.

    1985-08-01

    Experimental and computational methods are presented for the complete characterization of the thermoluminescence response obtained from thermoluminescent phosphors upon exposure to localized Gaussian laser heating beams. A number of different phosphor configurations are described as examples. These include LiF:Mg,Ti (TLD-100, Harshaw Chemical Corporation) in form of chips, which are widely used in the dosimetry of ionizing radiation, and thin-layer dosimeters prepared either as self-supporting films or powder in a polyimide matrix, or on substrates of LiF single crystals or borosilicate glass. It is demonstrated that all relevant optical and thermal properties of the dosimeters can be determined by these methods and that, based on this knowledge, the expected thermoluminescence response of a given configuration can be simulated as a function of a number of experimental parameters.

  4. Metallurgical analysis and high temperature degradation of the black chrome solar selective absorber

    SciTech Connect

    Lampert, C.M.

    1980-03-01

    The characteristics of black chrome, a solar selective absorber, have been the object of much interest by solar materials scientists. For this study, a well known coating, Harshaw Chemical Company's Chromonyx was selected for detailed scrutiny of its properties and degradation modes when exposed to high temperatures. Both as-plated and annealed microstructural models were presented. Technical means used in this microstructural characterization were: scanning and transmission electron microscopy, Auger depth profiling hemispherical reflectance and energy dispersive x-ray analysis. From these results a physical metallurgical model for wavelength selective properties of the coating was developed. Thus, it was observed that black chrome degraded as Cr/sub 2/O/sub 3/ oxide particles grew and chromium depleted. This effect was pronounced in air and to a lesser degree in medium vacuum. Oxidation by preferential diffusion and outgassing which causes structural changes, may take place.

  5. Technical aspects of the Naval Dosimetry Center quality assurance programme.

    PubMed

    St John, T J; Cassata, J R; Blake, P K; Wallace, W H; Minniti, R

    2006-01-01

    The purpose of this paper is to describe the technical aspects of the Naval Dosimetry Center (NDC) quality programme. The Navy has been formally monitoring personnel for occupational exposure to ionising radiation since at least 1946. The current system, the DT-702/PD, is the Harshaw 8840 holder and 8841 card. New card and holder checks are performed to verify that the correct LiF elements and holder filters are in the correct location and are of the correct composition. Element correction coefficient (ECC) magnitude and repeatability are also verified. Several quality assurance parameters are checked by a specially designed shipping machine. Calibration cards are used to calibrate each reader and quality control cards are inserted throughout a group of field cards to verify reader operation during the read process. The success of the programme is measured by annual proficiency tests administered by the National Voluntary Laboratory Accreditation Programme and Pacific Northwest National Laboratories. PMID:16757494

  6. Atomic size effects on recombination processes during thermoluminescence in doped crystals

    NASA Astrophysics Data System (ADS)

    Mdebuka, A. M.

    1993-10-01

    Atomic size effects on recombination processes during thermoluminescence (TL) in KCl: Harshaw (nominally pure samples), KCl: Ag (14 ppm), KCl: Na(>250 ppm) and KCl: Li (1 ppm) following room temperature (RT) γ-irradiation (20Mrad) has been examined. Results show that the stability of defects increases with decreasing dopant atomic size. (Peak temperatures are 210°C, 255°C and 277, 5°C in Ag-doped Na-doped and Li-doped samples respectively.) The trap-depth also increases as atomic size of dopants decreases. Emission spectrum indicates that only a perturbation of the well known band peak at 440 nm is caused by impurities. Additional band peaks occur in Ag-doped samples.

  7. Measurement of acid site density on molybdenum sulfide

    SciTech Connect

    Hou, P.; Wise, H.

    1982-12-01

    The method involves the room-temperature chemisorption of a base, such as ammonia, on the surface of molybdenum sulfide in the absence of any support material. For these measurements the catalyst sample was exposed at 300 K to pulses of ammonia (1 to 10 vol % in He) in a microreactor system connected to a thermal conductivity cell. The acidity measurements were conducted with a sample of molybdenum sulfide (catalyst A). The results of the surface-area measurements (BET/N/sub 2/) and the ammonia saturation coverage, identified as acid site equivalent, are listed. Similar results were obtained with a commercial catalyst of molybdenum sulfide (catalyst B, Harshaw M0-0401-T).

  8. Mechanical and optical properties of forged NaCl

    NASA Astrophysics Data System (ADS)

    Graves, G. A.; Detrio, J. A.; McCullum, D.; Dempsey, D. A.

    1980-07-01

    The mechanical and infrared laser absorption properties were determined on test specimens cut from a 32 cm diameter forging of Polytran Nacl produced by Harshaw. The homogeneity of the mechanical and optical properties statistically showed a significant dependence of the ultimate strength on azimuthal position in the forging. The absorption of the specimens at CO2, CO, HF/DF, and Nd:YAG laser wavelengths were measured and no significant dependence on specimen location was observed. The absorption variations were less than 10 percent for all of the laser wavelengths studied except at 3.8 micrometers (40 percent). Other properties examined include: specific heat; thermal expansion; and hardness. Strength measurements were made with both uniaxial flexural bars and biaxial disc test specimens.

  9. Optical Figuring And Evaluation Of 18" NaCl Windows

    NASA Astrophysics Data System (ADS)

    Shrader, E. F.; Bastien, G.

    1980-11-01

    To facilitate the production of 18" diameter NaC1 windows for the Antares Inertial Confinement Fusion Program of LASL, Harshaw has an optical evaluation test facility in the same room as the polishing machines. The principal optical test instrument is an 18" Zygo Fizeau interferometer. The photographed interferogram from the interferometer is digitized manually using a BITPAD* coordinate digitizer and PET 200l** computer. The computer has been programmed (in Basic) to fit, by least squares, the fringe coordinates to the best spherical fit over the clear aperture. The output gives the best fit (sphere) and wedge (linear) and the RMS deviation of wave front from best fit. An interferogram can be reduced in less than ten minutes. The cost of the reduction equipment was less than $2,000.00.

  10. Stereotactic radiosurgery dosimetry using thermoluminescent dosimeters and radiochromic films

    NASA Astrophysics Data System (ADS)

    Ávila-Rodríguez, Miguel A.; Rodríguez-Villafuerte, Mercedes; Perches, Rodolfo Díaz

    2000-10-01

    In this work we present a protocol to measure absorbed dose distributions in stereotactic radiosurgery treatments with a linear accelerator (Linac) using thermoluminescent dosimeters (TLD) and radiochromic dye films. A Linac Philips SL-15 (6 MV X-rays), a ZD2 stereoactic system for localizing the target via computed tomography (CT), and Leibinger radiosurgery accessories will be used. A versatile spherical acrylic phantom of 16 cm diameter to measure the dose distributions has been designed. The phantom is composed of two hemispheres. On one flat side of the hemispheres an array of Harshaw/Bicron TLD-100 or a sheet of GafChromic MD-55 film will be placed. The phantom will be irradiated in three different orientations to obtain spatial dose distributions in the coronal, sagital and transverse planes. The experimental measurement will be compared with the results provided by a commercial treatment-planning system.

  11. Preirradiation sensitivity loss of reader-annealed LiF TLDs

    SciTech Connect

    Poeton, R.W.; Stanford, N.; Scannel, M.J.

    1987-01-01

    Yankee Atomic Electric Company (YAEC) maintains a thermoluminescent dosimeter (TLD) dosimetry service using a Harshaw TLD badge system consisting of two TLD cards in a plastic case and automatic 2271 readers. Beginning in 1986, a standardized on-site quality assurance testing program was instituted for the facilities provided with YAEC personnel dosimetry. Results obtained during the first half of 1986 indicated a low bias in test TLD results on the order of 10 to 15%. A subsequent investigation attributed this bias to a previously unidentified loss in the sensitivity of reader-annealed LiF TLDs with storage time prior to irradiation. The discovery of this effect, based on in-plant quality assurance testing, demonstrates the usefulness of even relatively simple quality assurance tests by users themselves, regardless of the apparent thoroughness of other testing.

  12. In vivo thermoluminescence dosimetry for total body irradiation.

    PubMed

    Palkosková, P; Hlavata, H; Dvorák, P; Novotný, J; Novotný, J

    2002-01-01

    An improvement in the clinical results obtained using total body irradiation (TBI) with photon beams requires precise TBI treatment planning, reproducible irradiation, precise in vivo dosimetry, accurate documentation and careful evaluation. In vivo dosimetry using LiF Harshaw TLD-100 chips was used during the TBI treatments performed in our department. The results of in vivo thermoluminescence dosimetry (TLD) show that using TLD measurements and interactive adjustment of some treatment parameters based on these measurements, like monitor unit calculations, lung shielding thickness and patient positioning, it is possible to achieve high precision in absorbed dose delivery (less than 0.5%) as well as in homogeneity of irradiation (less than 6%). PMID:12382820

  13. Optimum parameters of TLD100 powder used for radiotherapy beams calibration check

    SciTech Connect

    Arib, M. . E-mail: mehenna.arib@comena-dz.org; Yaich, A.; Messadi, A.; Dari, F.

    2006-10-01

    External audit of the absorbed dose determination from radiotherapy machines is performed using Lithium fluoride (LiF) TLD-100. Optimal parameters needed to obtain highly accurate dosage from LiF powder was investigated, including the setup of the Harshaw 4000 reader. A linear correspondence between the thermoluminescent signal and the mass of the powder was observed, demonstrating that the dose can be evaluated with small samples of powder. The reproducibility of the thermoluminescence dosimeter (TLD) readings obtained with up to 10 samples from 1 capsule containing 160 mg of powder was around 1.5% (1 standard deviation [SD]). The time required for the manual evaluation of TLDs can be improved by 3 readings without loss of accuracy. Better reproducibility is achieved if the capsules are evaluated 7 days after irradiation using a nitrogen flow of 300 cc/min.

  14. Optimum parameters of TLD100 powder used for radiotherapy beams calibration check.

    PubMed

    Arib, M; Yaich, A; Messadi, A; Dari, F

    2006-01-01

    External audit of the absorbed dose determination from radiotherapy machines is performed using Lithium fluoride (LiF) TLD-100. Optimal parameters needed to obtain highly accurate dosage from LiF powder was investigated, including the setup of the Harshaw 4000 reader. A linear correspondence between the thermoluminescent signal and the mass of the powder was observed, demonstrating that the dose can be evaluated with small samples of powder. The reproducibility of the thermoluminescence dosimeter (TLD) readings obtained with up to 10 samples from 1 capsule containing 160 mg of powder was around 1.5% (1 standard deviation [SD]). The time required for the manual evaluation of TLDs can be improved by 3 readings without loss of accuracy. Better reproducibility is achieved if the capsules are evaluated 7 days after irradiation using a nitrogen flow of 300 cc/min. PMID:16905448

  15. Evaluation of spurious readings in Los Alamos personnel TL dosimeters

    SciTech Connect

    Eisen, Y.; Littlejohn, G.J.; Cortez, J.R.

    1984-08-01

    This study investigates the possibility of tritium build-up in TLD-600 chips irradiated with neutrons and the causes of spurious readings in the Harshaw TLD cards used for personnel dosimetry. Experiments indicated that spurious readings in TLD-600 chips, previously irradiated with neutrons, might occur in cases where the cards had been accidentally read at temperatures lower than 300/sup 0/C as a result of bad contact between the hot finger in the reading system and the chips. Because a TLD card contains glue and paper bar-code labels, the postannealing is performed at 80/sup 0/C for 17 hours. This annealing procedure alone does not effectively deplete the high-energy traps, such as those near 260/sup 0/C, populated by high-LET (Linear Energy Transfer) particles. TLD-600 chips, irradiated on a phantom by 400 mrem of moderated fission neutrons, read at 240/sup 0/C, annealed at 80/sup 0/C for 17 hours, and then reread at 280/sup 0/C, showed residual doses as large as 200 mrem (equivalent photons). Calculations and experiments show that for neutron exposures around 1 rem of moderated fission neutrons with an average energy of 500 keV, the maximum build-up of dose as a result of tritium formation is less than 1 mrem. The dose build-up in properly annealed TLD-600 and TLD-700 chips, is nearly the same, even though the TLD-600 chips were previously irradiated by neutrons. Both kinds of chips show natural background accumulation. A mechanism for annealing the Harshaw cards at high temperatures, without destroying the label or the adhesive material, was developed and found to be useful. 7 references, 4 figures, 3 tables.

  16. Distributed control, multiple pH loops optimize heavy metal waste treatment

    SciTech Connect

    Narvarte, S.; Koch, C.

    1985-11-01

    Pigments that generate separate waste streams containing lead chromate, Cadmium, organic pigments, and pigment dispersion are produced at the Louisville, KY, plant of Harshaw/Filtrol. The original waste treatment system comingled the four streams during treatment. Primary neutralization of the resultant stream consisted of ferrous sulfate additions to control oxidation reduction potential and sodium hydroxide to adjust pH level. The pH level was selected to precipitate heavy metals for later filtration and removal. The objective is to minimize the solubility of the different metals by controlling the stream's pH. But the minimum solubilities for the stream's different metals occur at widely varying pH levels. This broad pH range made it difficult to optimize wastewater control despite the use of a powerful distributed control system and operator interface. The new wastewater treatment system designed for the plant precipitates the heavy metals individually. Separate pH control of the stream containing cadmium pigments, for example optimizes solubility conditions for precipitating cadmium. Similarly, separate pH control loops optimize precipitation of lead and chrome. The new treatment system essentially doubles the instrumentation requirements for the plant. It will contain multiple pH monitors and loop controls. But the nature of the distributed control system has simplified expansion of the control system. To expand the control system for the new waste treatment plant Harshaw/Filtrol has simply added two more controller files. Since the treatment plant's operator station has a capacity for eight controller even after expansion the new system is still at half capacity. Start-up of the expanded waste treatment plant is scheduled for the first quarter of 1986. No problems are anticipated.

  17. Catalytic methods for improved coal liquefaction and hydrotreating. Quarterly report No. 3, March 23-June 22, 1986

    SciTech Connect

    Hirschon, A.S.; Laine, R.M.; Wilson, R.B. Jr.

    1986-07-01

    The goal of this project is to optimize the reaction conditions for coal liquefaction and upgrading coal liquids. Our results for this quarter are summarized by task. Task 1. Synthesis of Catalysts. During this quarter we synthesized two more ''doped'' Harshaw catalysts. One was sulfided CoMo catalyst doped with rhodium, and the other was a sulfided NiMo catalyst doped with ruthenium. Task 2. HDN Activity of Catalysts with Model Systems. This quarter we tested the effects of the bulk metals osmium, rhenium, and rhodium on the HDN of THQ and compared the results to those from ruthenium, molybdenum, and nickel. The bulk ruthenium was found to be far more active than any of the other bulk metals. We also tested the effects of the ruthenium-doped catalyst on the hydrogenation of propylbenzene under HDN conditions and found that the presence of quinoline greatly retards the hydrogenation of propylbenzene. We ran the Harshaw CoMo catalyst under HDN conditions at 100 psig of H/sub 2/ to compare with the RuCoMo catalyst under similar reaction conditions and found that the CoMo catalyst was essentially inactive. We also tested the doped RhCoMo catalyst and found that it had a poorer selectivity toward aromatic products than the other catalysts. When we tested the doped RuNiMo catalyst, however, we found a much higher selectivity to propylbenzene - even higher than with the doped ruthenium CoMo catalyst. Task 3. Catalytic Reactions and Additives on Coal and Coal Liquids. We recently submitted a manuscript to Theophrastus Publications on our use of additives and catalysts for HDN reactions. The manuscript is enclosed in Appendix B. The two papers in the appendices were processed separately for inclusion in the Energy Data Base. 6 refs., 5 figs., 1 tab.

  18. Combined shift and methanation in a fluidized-bed reactor. Quarterly progress report, 1 April-30 June 1980

    SciTech Connect

    Streeter, R C

    1980-07-01

    Only one bench-scale reactor test was completed. The Harshaw Ni/Cu/Mo and UCI (composition undisclosed) catalysts were evaluated over a 12-day period at 800 F and a feed gas H/sub 2//CO ratio of 2/1. Initial conversions with both catalysts were about 33 percent; and the activities of both samples declined steadily during the test, with final conversion values in the 15 to 20 percent range. During this test, problems were experienced with water carryover into the Drierite traps, necessitating some major design changes in the water letdown system. Two subsequent attempts to initiate a second test at 950 F with these catalysts were unsuccessful for the reasons given. A 5-day PEDU test (Test SM-2) was conducted using the spent Harshaw Ni/Cu/Mo catalyst from Test SM-1 in February. The purpose was to continue the data period at H/sub 2//CO = 1/1 that was terminated prematurely during the earlier PEDU test. After a brief baseline period (H/sub 2//CO = 3/1), during which catalyst activity appeared to be normal, the feed gas was changed to approximately 31 percent H/sub 2/, 31 percent CO, 22 percent CO/sub 2/, and 16 percent CH/sub 4/; and steam was added to the feed. Some difficulty was experienced in maintaining high bed temperatures, with the result that the steam flow had to be gradually decreased. This may have enhanced catalyst coking, since the catalyst activity generally declined slowly throughout the test, and the final carbon content of the catalyst was 3.6 percent (vs. 2.0 percent at the beginning of the test). A second 5-day PEDU test (Test SM-3) was conducted using the Climax Ni/Mo catalyst. The results are described.

  19. Novel catalytic methods for heteroatom removal in coal liquids upgrading. Quarterly report No. 1, September 1-December 1, 1983

    SciTech Connect

    Laine, R.M.; Hirschon, A.S.; Wilson, R.B. Jr.; Sundback, K.

    1983-12-01

    We are presently conducting baseline studies designed to establish the reactions of the coal liquids with the strong nucleophiles in the absence of catalysts. We are also establishing baseline conditions for commercial (Harshaw) HDN catalysts based on method of catalyst activation (with and without sulfiding), quantity of catalyst added, and quantities of coal liquid used in our reactor configuration. SRC-II middle distillate was obtained from the Pittsburg and Midway Mining Company SRC pilot plant at Ft. Lewis, Washington. The cobalt-molybdenum catalyst, HT-400 (3 wt % CoO, 15.1 wt % MoO/sub 3/, on Al/sub 2/O/sub 3/) was obtained from Harshaw Chemical Company. Hydrogen sulfide (H/sub 2/S) was obtained from Matheson. Hydrogen (H/sub 2/), nitrogen (N/sub 2/), and an H/sub 2/S (10%)/H/sub 2/ gas mixture were obtained from Liquid Carbonic. Hydrogenation reactions have been performed in a 300-mL Autoclave Engineers (AE) Magnedrive stirred reactor, heated with a 1000-watt electric furnace (AE). The temperature was controlled with a model CP temperature controller (AE). The autoclave was connected through a sample gas vent to a Carle Series S gas chromatograph adapted by Carle to analyze C/sub 1/-C/sub 3/, H/sub 2/, O/sub 2/, N/sub 2/, and H/sub 2/S. For gas analyses, the autoclave was vented into the 1-mL sample injection port of the GC. Nuclear magnetic resonance spectra were obtained on a JOEL FX 90Q spectrometer.

  20. Ambient Dose Equivalent measured at the Instituto Nacional de Cancerologia Department of Nuclear Medicine

    SciTech Connect

    Avila, O.; Torres-Ulloa, C. L.; Medina, L. A.; Trujillo-Zamudio, F. E.; Gamboa de Buen, I.; Buenfil, A. E.; Brandan, M. E.

    2010-12-07

    Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerologia, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with {sup 137}Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrologia, to known {sup 137}Cs gamma radiation air kerma. Radionuclides considered for this study are {sup 131}I, {sup 18}F, {sup 67}Ga, {sup 99m}Tc, {sup 111}In, {sup 201}Tl and {sup 137}Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placed during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with {sup 131}I and {sup 137}Cs. High dose values were found at the waste storage room, outside corridor of {sup 137}Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the {sup 137}Cs brachytherapy corridor is equal to (18.51{+-}0.02)x10{sup -3} mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05{+-}0.03)x10{sup -3} mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).

  1. Dose received by occupationally exposed workers at a nuclear medicine department

    SciTech Connect

    Avila, O.; Sanchez-Uribe, N. A.; Rodriguez-Laguna, A.; Medina, L. A.; Estrada, E.; Buenfil, A. E.; Brandan, M. E.

    2012-10-23

    Personal Dose Equivalent (PDE) values were determined for occupational exposed workers (OEW) at the Nuclear Medicine Department (NMD) of 'Instituto Nacional de Cancerologia' (INCan), Mexico, using TLD-100 thermoluminescent dosemeters. OEW at NMD, INCan make use of radiopharmaceuticals for diagnosis and treatment of diseases. Radionuclides associated to a pharmaceutical compound used at this Department are {sup 131}I, {sup 18}F, {sup 68}Ga, {sup 99m}Tc, {sup 111}In and {sup 11}C with main gamma emission energies between 140 and 511 keV. Dosemeter calibration was performed at the metrology department of 'Instituto Nacional de Investigaciones Nucleares' (ININ), Mexico. Every occupational worker used dark containers with three dosimeters which were replaced monthly for a total of 5 periods. Additionally, control dosemeters were also placed at a site free of radioactive sources in order to determine the background radiation. Results were adjusted to find PDE/day and estimating annual PDE values in the range between 2 mSv (background) and 9 mSv. The mean annual value is 3.51 mSv and the standard deviation SD is 0.78 mSv. Four of the 16 OEW received annual doses higher than the average +1 SD (4.29 mSv). Results depend on OEW daily activities and were consistent for each OEW for the 5 studied periods as well as with PDE values reported by the firm that performs the monthly service. All obtained values are well within the established annual OEW dose limit stated in the {sup R}eglamento General de Seguridad Radiologica{sup ,} Mexico (50 mSv), as well as within the lower limit recommended by the 'International Commission on Radiation Protection' (ICRP), report no.60 (20 mSv). These results verify the adequate compliance of the NMD at INCan, Mexico with the norms given by the national regulatory commission.

  2. Dose received by occupationally exposed workers at a nuclear medicine department

    NASA Astrophysics Data System (ADS)

    vila, O.; Snchez-Uribe, N. A.; Rodrguez-Laguna, A.; Medina, L. A.; Estrada, E.; Buenfil, A. E.; Brandan, M. E.

    2012-10-01

    Personal Dose Equivalent (PDE) values were determined for occupational exposed workers (OEW) at the Nuclear Medicine Department (NMD) of "Instituto Nacional de Cancerologa" (INCan), Mexico, using TLD-100 thermoluminescent dosemeters. OEW at NMD, INCan make use of radiopharmaceuticals for diagnosis and treatment of diseases. Radionuclides associated to a pharmaceutical compound used at this Department are 131I, 18F, 68Ga, 99mTc, 111In and 11C with main gamma emission energies between 140 and 511 keV. Dosemeter calibration was performed at the metrology department of "Instituto Nacional de Investigaciones Nucleares" (ININ), Mexico. Every occupational worker used dark containers with three dosimeters which were replaced monthly for a total of 5 periods. Additionally, control dosemeters were also placed at a site free of radioactive sources in order to determine the background radiation. Results were adjusted to find PDE/day and estimating annual PDE values in the range between 2 mSv (background) and 9 mSv. The mean annual value is 3.51 mSv and the standard deviation SD is 0.78 mSv. Four of the 16 OEW received annual doses higher than the average +1 SD (4.29 mSv). Results depend on OEW daily activities and were consistent for each OEW for the 5 studied periods as well as with PDE values reported by the firm that performs the monthly service. All obtained values are well within the established annual OEW dose limit stated in the "Reglamento General de Seguridad Radiolgica", Mxico (50 mSv), as well as within the lower limit recommended by the "International Commission on Radiation Protection" (ICRP), report no.60 (20 mSv). These results verify the adequate compliance of the NMD at INCan, Mexico with the norms given by the national regulatory commission.

  3. Ambient Dose Equivalent measured at the Instituto Nacional de Cancerología Department of Nuclear Medicine

    NASA Astrophysics Data System (ADS)

    Ávila, O.; Torres-Ulloa, C. L.; Medina, L. A.; Trujillo-Zamudio, F. E.; de Buen, I. Gamboa; Buenfil, A. E.; Brandan, M. E.

    2010-12-01

    Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerología, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with 137Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrología, to known 137Cs gamma radiation air kerma. Radionuclides considered for this study are 131I, 18F, 67Ga, 99mTc, 111In, 201Tl and 137Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placed during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with 131I and 137Cs. High dose values were found at the waste storage room, outside corridor of 137Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the 137Cs brachytherapy corridor is equal to (18.51±0.02)×10-3 mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05±0.03)×10-3 mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).

  4. Assessment of the radiological safety of a Genoray portable dental X-ray unit

    PubMed Central

    Hafezi, L; Manafi, F; Talaeipour, A R

    2015-01-01

    Objectives: The portable dental radiographic systems are generally used in emergency situations (e.g. during natural disasters) for disabled/aged patients and in patient rooms. This study assesses the output exposure of a portable dental radiographic system measured using thermoluminescent dosemeters (TLDs). Methods: Occupational exposure of the operator was determined when the portable dental unit was used for mandibular and maxillary teeth exposure. Results: The doses of some critical organs of an operator were measured using TLDs implanted within the Rando phantom. Conclusions: Considering the annual organ dose limits, the eye lens dose limit is the main factor determining the frequency of system application. PMID:25343709

  5. Analiza niepewności pomiaru współczynnika wzorcowania dawkomierzy terapeutycznych i diagnostycznych, wzorcowanych w polskim Laboratorium Wtórnych Wzorców Dozymetrycznych

    NASA Astrophysics Data System (ADS)

    Ulkowski, Piotr; Bulski, Wojciech; Gwiazdowska, Barbara

    2011-01-01

    The aim of the study was to work out a method of establishing the measurement uncertainty and determination of uncertainty values for calibration of dosemeters at the SSDL. For the determination of type A and B uncertainties, a method according to iternational ISO standard was used. The calibration procedures used at the SSDL, consistent with the reports of the International Atomic Energy Agency, were taken into account. The presented results apply to all dosimeters calibrated at the SSDL. The detailed analysis of every step of the calibration procedures and the results obtained show that the measurement uncertinty is within the limits accepted by the Polish Centre for Accreditation.

  6. Optically stimulated luminescence (OSL) response of Al2O3:C, BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors.

    PubMed

    Kumar, Pratik; Bahl, Shaila; Sahare, P D; Kumar, Surender; Singh, Manveer

    2015-12-01

    This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors for different doses and bleaching durations. The results have also been compared with the commercially available Landauer Al2O3:C (Luxel) dosemeter. Nanocrystalline K2Ca2(SO4)3:Eu is known to be a sensitive thermoluminescent phosphor, but its OSL response is hardly reported. At first, pellets of nanocrystalline K2Ca2(SO4)3:Eu powder were prepared by adding Teflon as a binder. Their OSL signal was compared with that of the material in pure form, i.e. without adding the binder (in 100:1 ratio). It was observed that adding the binder does not appreciably affect the OSL intensity. On comparison with the commercially available Al2O3:C from Landauer, it was found that K2Ca2(SO4)3:Eu is around 15 times less sensitive than Al2O3:C. 'Homemade' BaFCl:Eu phosphor has also been studied. The intensity of BaFCl:Eu was ?20 times more than the standard Al2O3:C dosemeter and ?200 times more sensitive than K2Ca2(SO4)3:Eu in the dose range of 13-200 cGy. OSL dosemeters are believed to give luminescence signal even if they are read before, i.e. multiple reading may be possible under suitable conditions after single exposure. This was also checked for all the prepared dosemeters and it was found that Al2O3:C showed the least decrease of <2 %, followed by BaFCl:Eu of 15 % and K2Ca2(SO4)3:Eu with 20 %. Finally, Al2O3:C and BaFCl:Eu phosphors were also studied for their optical bleaching durations to which the respective signals get completely removed so that the phosphor can be re-used. It was observed that BaFCl:Eu is bleached faster and more easily than Al2O3:C. PMID:25646524

  7. Cooling rate effects in thermoluminescence dosimetry grade lithium flouride. Implications for practical dosimetry.

    PubMed

    Mason, E W; McKinlay, A F; Clark, I

    1976-01-01

    A systematic investigation of the effects of cooling rates in the range of 10(-1) to 2 X 10(5) degrees C min-1 applied to TLD-700, LiF thermoluminescence dosemeters has shown that the 'transfer sensitivity' effect observed by Booth, Johnson and Attix (1972) is only of importance for cooling rates greater than 10(3) degrees C min-1. Although it is concluded that for practical dosimetry purposes the effect may be ignored it is not clear why Booth et al. observed such large changes and until this discrepancy is explained it is recommended that a low temperature pre-irradiation anneal should be used. PMID:1267932

  8. Photon doses in NPL standard neutron fields.

    PubMed

    Roberts, N J; Horwood, N A; McKay, C J

    2014-10-01

    Standard neutron fields are invariably accompanied by a photon component due to the neutron-generating reactions and secondary neutron interactions in the surrounding environment. A set of energy-compensated Geiger-Mller (GM) tubes and electronic personal dosemeters (EPDs) have been used to measure the photon dose rates in a number of standard radionuclide and accelerator-based neutron fields. The GM tubes were first characterised in standard radioisotope and X-ray photon fields and then modelled using MCNP to determine their photon dose response as a function of energy. Values for the photon-to-neutron dose equivalent ratios are presented and compared with other published values. PMID:24126485

  9. Novel catalytic methods for heteroatom removal in coal liquids upgrading. Quarterly report No. 2, December 1, 1983-March 1, 1984

    SciTech Connect

    Laine, R.M.; Hirschon, A.S.; Wilson, R.B. Jr.

    1984-03-01

    The goal of this project is to optimize the conditions for the coal liquefaction stage of coal refinement. This work is divided into three tasks; this quarter we report the results of our work on the first two tasks. In Task 1 we concentrated on baseline studies designed to establish the role of hydrogen sulfide in the absence of catalyst. We also established some baseline conditions for a commercial (Harshaw) HDN catalyst based on (1) method of catalyst activation (with and without sulfiding), (2) quantity of catalyst added, and (3) quantities of coal liquid used in our reactor configuration. We found that without catalyst, H/sub 2/S/H/sub 2/ has no effect on the coal liquid under upgrading conditions. However, when H/sub 2/S/H/sub 2/ is used with catalyst, the nitrogen content in the coal liquid is significantly reduced when compared with runs with catalyst and H/sub 2/ alone. In no case did we observe any sulfur incorporation. In a complementary study, partly funded by EPRI, we studied the interaction of H/sub 2/S with potential coal model compounds and with coal. From the work on coal models we found that H/sub 2/S promotes hydrogen transfer from tetralin to the models or to coal and aids in removing oxygen from the coal models. We also found that the addition of H/sub 2/S aids in the liquefaction of coal. We will submit the results of our work to Fuel. Abstracts of the manuscripts (in preparation) are attached (Appendix A). In Task 2 we began the synthesis of some organometallic molybdenum cluster complexes. We also investigated the mechanism of the HDN process with the Harshaw catalyst and quinoline as a model. We reported our proposed mechanism at the California Catalysis Society Conference of March 23, 1984. The abstract of the talk is given in Appendix B. We will shortly submit a paper on our results to the Journal of Molecular Catalysis. 5 references, 2 figures, 3 tables.

  10. Novel catalytic methods for heteroatom removal in coal liquids upgrading. Quarterly report No. 7, March 1-June 1, 1985. [CF/sub 3/SO/sub 3/H and CF/sub 3/COOH

    SciTech Connect

    Laine, R.M.; Hirschon, A.S.; Wilson, R.B. Jr.

    1985-06-01

    The goal of this project is to optimize the reaction conditions for upgrading coal liquids. Results for this quarter are summarized below by task. Task 1: This quarter we tested the effect of H/sub 2/S on a sulfided NiMo catalyst obtained from Harshaw. We found that, unlike our results with the CoMo catalyst, the addition of H/sub 2/S to the NiMo catalyst showed no effect on the HDN process under our conditions for upgrading an SRC-II liquid. However, CoMo with H/sub 2/S is almost as effective as NiMo, but consumes less hydrogen. Task 2: We tested several of the surface-confined catalysts that were prepared last quarter and found that the bimetallic NiMo catalysts have a high degree of HDN activity, but the same product selectivity as the corresponding catalysts made by conventional methods. Based on literature references to high activity of bulk ruthenium and ruthenium sulfide towards C-C and C-S bond cleavage, we performed some preliminary experiments with bulk ruthenium to test for HDN activity. Our initial experiments have shown that ruthenium exhibits a high degree of HDN activity at lower temperatures and displays a different selectivity than that shown with conventional catalysts. In other experiments, we added ruthenium to a Harshaw CoMo catalyst and found both an increase in HDN activity, and an increase in selectivity to unsaturated HDN products. This change in selectivity is the goal of this project and could be highly significant in lowering the cost of hydrotreated coal liquids. Task 3: We also tested the effects of acid on HDN in the absence of catalysts on both a quinoline solution and on an SRC-II liquid. Our results show that acid has no apparent effect on the quinoline. However, acid reduces the nitrogen content of the SRC-II liquid to the same level as the combination of catalyst and acid. 7 refs., 8 figs., 4 tabs.

  11. Further studies on the non-universality of the TL-LET response in thermoluminescent LiF and Li2B4O7: The effect of high temperature TL

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Kalef-Ezra, J.; Moscovitch, M.; Pinto, H.

    1980-06-01

    Three batches of thermoluminescent bulb dosimeters of LiF (TLD-100, 600, 700 - Harshaw) and two batches of Li2B4O7 (TLD-800 — Harshaw) were irradiated with 60Co γ rays, 13.54 meV monoenergetic neutrons and 3.8 MeV alphas. The relative population of high temperature TL peaks (peaks 6 and 7 in LiF) was found to be both batch and ionization density dependent with ɛT>1n=0.206±0.02, ɛT>2n=0.288±0.02, ɛT>1α=0.205±0.02, ɛT >2α=0.316±0.02, ɛT>3α=0.355±0.02, and ɛT>1γ=0.035±0.01ɛT>2γ=0.102±0.015, ɛT>3γ=0.123±0.015. In li2B4O7, no variationa was observed in the glow structure as a function of batch or type of radiation. It follows immediately, therefore, that the batch variations previously reported by Horowitz et al. in the relative total TL production efficiency, η, remain unchanged at η1 = 0.775 ± 0.007 and η2 = 1.105 ± 0.017 in Li2B 4O7. We calculate batch values of the relative partial TL production efficiency for LiF, η4+5, to be 0.288 ± 0.008 and 0.333 ± 0.008 for batches 1 and 2 respectively following neutron irradiation and 0.14 ± 0.02, 0.16 ± 0.01 and 0.213 ± 0.015 for batches 1, 2, 3 respectively following alpha irradiation. The batch variations in η4+5 (i.e. the major dosimetric peaks in LiF) remain, therefore, 14.5% and 41.4% following neutron and alpha irradiation respectively. The batch variations in η and ɛT> are apparently associated with large variations in the concentrations of Ba, Al and Cr in LiF and Al, Si in Li2B4O7. The previous conclusions arrived at by Horowitz et al., regarding the non-universality of the TL-LET dependence in LiF and Li2B4O7 cannot be explained by batch variations of high temperature TL and remain, therefore, unmodified.

  12. Thermoluminescent characteristics of new pre-calibrated dosimeters (TLD) in commercially available readers for selected applications

    NASA Astrophysics Data System (ADS)

    Tawil, R. A.; Pontikos, P.; Szalanczy, A.; Velbeck, K.; Bruml, W.; Rotunda, J. E.

    1994-12-01

    This paper reports the performance of newly developed pre-calibrated Thermoluminescent Dosimeters (TLD) with a description and performance results for two commercially available TLD readers. Introduced for use in basic research, medical diagnostics and therapy applications, the Harshaw Model 5500 Automatic TLD Reader evaluates up to 50 dosimeters (rods, chips, disks, μ-cubes) per loading; the Harshaw Model 3500 Manual TLD Reader evaluates single dosimeters and powder. Tests were conducted using the International Electrotechnical Commission (IEC) guidelines for TLD readers to determine system performance and compliance. Both instruments passed the compliance standards in all tests established by the IEC: detection thresholds for both instruments were less than 10μGy, reproducibility was better than 0.7%, sensitivity to ambient light was less than 0.2 Hmax (where Hmax is the maximum detection threshold), TL residue was less than 1% of the total integral charge, stability less than 1% deviation after a 24 hour warm-up period, linearity was within specification, test light stability was under 1%, and power leakage requirements set forth by UL-544 (less than 500 μA AC RMS leakage) was less than 42 μA AC RMS in all cases. The characteristics of newly introduced, factory calibrated, extruded TLD-100 rods were investigated by studying the consistency of the Element Correction Coefficients (ECCs) under a variety of conditions. The ECC (< x> / xi) relates an individual dosimeter's response, xi, to the mean response, < x>, of the group. Supralinearity effects and the validity of ECCs generated at 1 cGy for use in the 50-900 cGy dose range were characterized and reported. The results for two specific applications, phantom studies with 60Co and at four Orthovoltage energies are also reported. Portability of Element Correction Coefficients from reader to reader was achieved with a relative standard deviation of less than 1.7%. The relative standard deviation of five TLDs exposed to various doses in the range of 50-900 cGy, with ECCs applied using a 1 cGy dose, yielded results under 2%. At Orthovoltage energies ranging from 100 kV p to 300 kV p, the corresponding relative standard deviations were less than 3%.

  13. In vivo dose evaluation during gynaecological radiotherapy using L-alanine/ESR dosimetry.

    PubMed

    Rech, Amanda Burg; Barbi, Gustavo Lazzaro; Ventura, Luiz Henrique Almeida; Guimares, Flavio Silva; Oliveira, Harley Francisco; Baffa, Oswaldo

    2014-06-01

    The dose delivered by in vivo 3-D external beam radiation therapy (EBRT) was verified with L-alanine/electron spin resonance (ESR) dosimetry for patients diagnosed with gynaecological cancer. Measurements were performed with an X-band ESR spectrometer. Dosemeters were positioned inside the vaginal cavity with the assistance of an apparatus specially designed for this study. Previous phantom studies were performed using the same conditions as in the in vivo treatment. Four patients participated in this study during 20-irradiation sessions, giving 220 dosemeters to be analysed. The doses were determined with the treatment planning system, providing dose confirmation. The phantom study resulted in a deviation between -2.5 and 2.1 %, and for the in vivo study a deviation between -9.2 and 14.2 % was observed. In all cases, the use of alanine with ESR was effective for dose assessment, yielding results consistent with the values set forth in the International Commission on Radiation Units and Measurements (ICRU) reports. PMID:24751984

  14. A review of recent advances in optical fibre sensors for in vivo dosimetry during radiotherapy.

    PubMed

    O'Keeffe, S; McCarthy, D; Woulfe, P; Grattan, M W D; Hounsell, A R; Sporea, D; Mihai, L; Vata, I; Leen, G; Lewis, E

    2015-06-01

    This article presents an overview of the recent developments and requirements in radiotherapy dosimetry, with particular emphasis on the development of optical fibre dosemeters for radiotherapy applications, focusing particularly on in vivo applications. Optical fibres offer considerable advantages over conventional techniques for radiotherapy dosimetry, owing to their small size, immunity to electromagnetic interferences, and suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based dosemeters, together with being lightweight and flexible, mean that they are minimally invasive and thus particularly suited to in vivo dosimetry. This means that the sensor can be placed directly inside a patient, for example, for brachytherapy treatments, the optical fibres could be placed in the tumour itself or into nearby critical tissues requiring monitoring, via the same applicators or needles used for the treatment delivery thereby providing real-time dosimetric information. The article outlines the principal sensor design systems along with some of the main strengths and weaknesses associated with the development of these techniques. The successful demonstration of these sensors in a range of different clinical environments is also presented. PMID:25761212

  15. Effect of background and transport dose on the results of the personal dose equivalent Hp(10) measurements in photon fields obtained during the intercomparison 2013 of the African region.

    PubMed

    Arib, M; Herrati, A; Dari, F; Lounis-Mokrani, Z

    2015-12-01

    As part of the intercomparison on the measurement of personal dose equivalent Hp(10), jointly organised by the International Atomic Energy Agency and the Algerian Secondary Standard Dosimetry Laboratory, for the African region, up to 12 dosemeters were added to the packages of the 28 participants to evaluate the background and transport dose (BGTD), received by the dosemeters before and after their irradiation at the SSDL (environmental irradiations, scanning process at the airports, etc.). Out of the 28 participants, only 17 reported the corresponding BGTD measured values, which lied between 0.03 and 0.8 mSv. The mean measured value of BG was (0.25±0.14) mSv, which is significantly high compared with the lowest dose value used in the intercomparison exercise. The BGTD correction shifted the overall results of the intercomparison from an overestimation of dose (∼8 % before applying BGT dose correction) to an underestimation of dose (-9 % after correction). The measurement protocol and the detailed analysis of the results and applied corrections are discussed in this paper. PMID:25433048

  16. Monte Carlo-derived TLD cross-calibration factors for treatment verification and measurement of skin dose in accelerated partial breast irradiation.

    PubMed

    Garnica-Garza, H M

    2009-03-21

    Monte Carlo simulation was employed to calculate the response of TLD-100 chips under irradiation conditions such as those found during accelerated partial breast irradiation with the MammoSite radiation therapy system. The absorbed dose versus radius in the last 0.5 cm of the treated volume was also calculated, employing a resolution of 20 microm, and a function that fits the observed data was determined. Several clinically relevant irradiation conditions were simulated for different combinations of balloon size, balloon-to-surface distance and contents of the contrast solution used to fill the balloon. The thermoluminescent dosemeter (TLD) cross-calibration factors were derived assuming that the calibration of the dosemeters was carried out using a Cobalt 60 beam, and in such a way that they provide a set of parameters that reproduce the function that describes the behavior of the absorbed dose versus radius curve. Such factors may also prove to be useful for those standardized laboratories that provide postal dosimetry services. PMID:19229101

  17. Aircrew exposure monitoring: results of 2001 to 2003 studies.

    PubMed

    Spurný, F; Turek, K; Vlcek, B; Dachev, Ts

    2004-01-01

    Aircrew exposure represents one of the recent subjects of occupational individual dosimetry. Since 1991 many new results have been found; there is however a need to gather further data on this exposure and its variation with geomagnetic position, solar activity and flight route parameters. Since 2001, many individual and six long-term monitoring programmes have been conducted onboard aircraft of Czech Airlines (CSA). In these programmes, a Si-diode spectrometer was fixed in an aircraft. Together with it, passive dosemeters thermoluminescent detector, track-etch based neutron dosemeter linear energy transfer and spectrometer) were exposed. More than 700 regular commercial flights were monitored in this manner. CSA supplied us also with full navigation data, which allowed us to calculate the exposure levels using EPCARD 3.2 and CARI6 codes. Direct experimental readings obtained with the detectors mentioned above were interpreted on the basis of calibrations in on-Earth reference fields and compared with calculated data. A satisfactory correlation between all sets of data was observed. PMID:15353673

  18. Occupational eye lens doses in interventional cardiology. A multicentric study.

    PubMed

    Sánchez, R M; Vano, E; Fernández, J M; Pifarré, X; Ordiales, J M; Rovira, J J; Carrera, F; Goicolea, J; Fernández-Ortiz, A

    2016-03-01

    New European regulation regarding radiological protection of workers and more specifically the new occupational dose limit for the eye lens recently reduced to 20 mSv yr(-1) may affect interventional cardiologists. This paper presents a set of measurements of occupational doses performed in five interventional cardiology centres and then compared with the new dose limit. The measurement of occupational doses was performed over the apron at chest level using electronic dosemeters recording H p(10). In one of the centres, scatter dose at goggles was also measured with optically stimulated luminescence dosemeters calibrated in terms of H p(0.07). An average H p(10) over the apron of 46 μSv/procedure was measured for cardiologists. Lower doses were noted in other professionals like second cardiologists, nurses or anaesthetists. Procedures for valvular and other structural heart diseases involved the highest occupational doses, averaging over 100 μSv/procedure. Important differences in occupational doses among centres may be indicative of different radiation protection habits. The new occupational dose limit for the eye lens is likely to be exceeded by those among the interventionalists who do not use protection tools (ceiling suspended screen and/or goggles) even with standard workloads. PMID:26861214

  19. Uncertainties in external dosimetry: analytical vs. Monte Carlo method.

    PubMed

    Behrens, R

    2010-03-01

    Over the years, the International Commission on Radiological Protection (ICRP) and other organisations have formulated recommendations regarding uncertainty in occupational dosimetry. The most practical and widely accepted recommendations are the trumpet curves. To check whether routine dosemeters comply with them, a Technical Report on uncertainties issued by the International Electrotechnical Commission (IEC) can be used. In this report, the analytical method is applied to assess the uncertainty of a dosemeter fulfilling an IEC standard. On the other hand, the Monte Carlo method can be used to assess the uncertainty. In this work, a direct comparison of the analytical and the Monte Carlo methods is performed using the same input data. It turns out that the analytical method generally overestimates the uncertainty by about 10-30 %. Therefore, the results often do not comply with the recommendations of the ICRP regarding uncertainty. The results of the more realistic uncertainty evaluation using the Monte Carlo method usually comply with the recommendations of the ICRP. This is confirmed by results seen in regular tests in Germany. PMID:19942627

  20. Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom

    PubMed Central

    Iqbal, K; Gillin, M; Summers, P A; Dhanesar, S; Gifford, K A; Buzdar, S A

    2013-01-01

    Objective: The purpose of this study was to evaluate spot scanning proton therapy with an anthropomorphic prostate phantom at the Proton Therapy Center of The University of Texas MD Anderson Cancer Center at Houston, TX (PTCH). Methods: An anthropomorphic prostate phantom from the Radiological Physics Center (RPC), The University of Texas MD Anderson Cancer Center, Houston, TX, was used, which contained thermoluminescent dosemeters and GAFCHROMIC EBT2 film (ISP Technologies, Wayne, NJ). The phantom was irradiated by the Hitachi synchrotron (Hitachi America, Ltd, Tarrytown, NY), and the results were compared between the treatment planning system (TPS) and RPC measurements. Results: RPC results show that the right/left, inferior/superior and posterior/anterior aspects of the coronal/sagittal and EBT2 film measurements were within 7%/4?mm of the TPS. The RPC thermoluminescent dosemeter measurements of the prostate and femoral heads were within 3% of the TPS. Conclusion: The RPC prostate phantom is a useful mechanism to evaluate spot scanning beam proton therapy within certain confidence levels. Advances in knowledge: The RPC anthropomorphic prostate phantom could be used to establish quality assurance of spot scanning proton beam for patients with prostate cancer. PMID:24049129

  1. The new EC technical recommendations for monitoring individuals occupationally exposed to external radiation.

    PubMed

    Alves, J G; Ambrosi, P; Bartlett, D T; Currivan, L; van Dijk, J W E; Fantuzzi, E; Kamenopoulou, V

    2011-03-01

    The purpose of the European Commission technical recommendations (TR) for monitoring individuals occupationally exposed to external radiation is to provide guidance on those aspects of the implementation of the European Union Parliament and Council Directives directly related to individual monitoring of external radiation, and to encourage harmonisation thereof. They are mainly aimed at the management and staff of IM services but also at manufacturers, laboratories supplying type-testing services, national authorities trying to harmonise approval procedures, and government bodies to harmonise regulations and guidance. The TR main topics are: objectives and aims of IM for external radiation; dosimetry concepts; accuracy requirements; calibration, type testing and performance testing; approval procedures; quality assurance and quality control; and dose record keeping. Attention is paid to particular aspects, such as wide energy ranges for the use of personal dosemeters, pulsed fields and non-charged particle equilibrium; and use of active personal dosemeters. The TR give proposals towards achieving harmonisation in IM and the eventual mutual recognition of services and of dose results. PMID:20959338

  2. Monte Carlo modelling of 90Sr/90Y and 85Kr beta fields for Hp(3) measurements.

    PubMed

    Eakins, J S; Baker, S T; Gibbens, N J; Gilvin, P J; Hager, L G; Tanner, R J

    2014-01-01

    In support of research aimed at developing a thermoluminescence dosemeter capable of accurately measuring ionising radiation doses to the lens of the eye, Monte Carlo modelling of a standard beta exposure set-up has been performed. It was found that electrons with an energy distribution corresponding to the beta emission spectrum from (85)Kr deposit negligible doses at a depth of 3 mm in tissue, but doses from (90)Sr/(90)Y are significant; free in air and fluence-to-Hp(3,θ°) and -Hp(0.07,θ°) conversion coefficient data were found for this field for exposures at 0°, 30° and 60° angles of incidence, and the response characteristics of the new eye dosemeter were evaluated. It was shown that the results were not affected greatly by the shape of the calibration phantom. However, it was demonstrated that the presence of intermediating air and beam flattening filters hardens the energy distribution of the field at the point of test, relative to a raw (90)Sr/(90)Y source, and this impacts dose depositions. PMID:23945747

  3. Development of age-specific Japanese head phantoms for dose evaluation in paediatric head CT examinations.

    PubMed

    Yamauchi-Kawaura, C; Fujii, K; Akahane, K; Yamauchi, M; Narai, K; Aoyama, T; Katsu, T; Obara, S; Imai, K; Ikeda, M

    2015-02-01

    In this study, the authors developed age-specific physical head phantoms simulating the physique of Japanese children for dose evaluation in paediatric head computed tomography (CT) examinations. Anatomical structures at 99 places in 0-, 0.5-, 1- and 3-y-old Japanese patients were measured using DICOM viewer software from CT images, and the head phantom of each age was designed. For trial manufacture, a 3-y-old head phantom consisting of acrylic resin and gypsum was produced by machine processing. Radiation doses for the head phantom were measured with radiophotoluminescence glass dosemeters and Si-pin photodiode dosemeters. To investigate whether the phantom shape was suitable for dose evaluation, organ doses in the same scan protocol were compared between the 3-y-old head and commercially available anthropomorphic phantoms having approximately the same head size. The doses of organs in both phantoms were equivalent. The authors' designed paediatric head phantom will be useful for dose evaluation in paediatric head CT examinations. PMID:24821932

  4. Monte Carlo-derived TLD cross-calibration factors for treatment verification and measurement of skin dose in accelerated partial breast irradiation

    NASA Astrophysics Data System (ADS)

    Garnica-Garza, H M

    2009-03-01

    Monte Carlo simulation was employed to calculate the response of TLD-100 chips under irradiation conditions such as those found during accelerated partial breast irradiation with the MammoSite radiation therapy system. The absorbed dose versus radius in the last 0.5 cm of the treated volume was also calculated, employing a resolution of 20 m, and a function that fits the observed data was determined. Several clinically relevant irradiation conditions were simulated for different combinations of balloon size, balloon-to-surface distance and contents of the contrast solution used to fill the balloon. The thermoluminescent dosemeter (TLD) cross-calibration factors were derived assuming that the calibration of the dosemeters was carried out using a Cobalt 60 beam, and in such a way that they provide a set of parameters that reproduce the function that describes the behavior of the absorbed dose versus radius curve. Such factors may also prove to be useful for those standardized laboratories that provide postal dosimetry services.

  5. Indoor concentration of radon, thoron and their progeny around granite regions in the state of Karnataka, India.

    PubMed

    Sannappa, J; Ningappa, C

    2014-03-01

    An extensive studies on the indoor activity concentrations of thoron, radon and their progeny in the granite region in the state of Karnataka, India, has been carried out since, 2007 in the scope of a lung cancer epidemiological study using solid-state nuclear track detector-based double-chamber dosemeters (LR-115, type II plastic track detector). Seventy-four dwellings of different types were selected for the measurement. The dosemeters containing SSNTD detectors were fixed 2 m above the floor. After an exposure time of 3 months (90 d), films were etched to reveal tracks. From the track density, the concentrations of radon and thoron were evaluated. The value of the indoor concentration of thoron and radon in the study area varies from 16 to 170 Bq m(-3) and 18 to 300 Bq m(-3) with medians of 66 and 82.3 Bq m(-3), respectively, and that of their progeny varies from 1.8 to 24 mWL with a median of 3.6 mWL and 1.6 to 19.6 mWL, respectively. The concentrations of indoor thoron, radon and their progeny and their equivalent effective doses are discussed. PMID:24106330

  6. Effects of ambient temperature on the FXG radiochromic gels used for 3-D dosimetry

    NASA Astrophysics Data System (ADS)

    Bero, M. A.; Kharita, M. H.

    2004-01-01

    Environmental effects on the optical properties of a sensitive radiochromic gel dosemeter; in particular storage, irradiation and measurements temperature were studied. Knowledge of light temperature and other ambient effects help to optimise working conditions and minimize errors. A ferrous-sulphate dosemeter with xylenol orange ion indicator incorporated in a gelatin gel matrix (FXG) was prepared under normal working conditions, and the samples were then kept in closed storage area at different temperature ranging from 5°C up to the gel melting temperature about 35°C. The samples optical absorbance was then measured quantitatively using double beam spectrophotometry. There is a small and steady increase in the absorbance 0.3×10-3 /°C with increasing temperature until about 30°C when we observe a big jump in the gel absorbance. Finally, additional important behaviour of FXG material was noticed, that is the changes occurred under the influence of rising temperature are reversible which is different from the permanent radiation caused changes.

  7. Occupational radiation exposure during removal of radioactive reactor components from GRR-1 pool.

    PubMed

    Kontogeorgakos, D; Tzika, F; Valakis, S; Stamatelatos, I E

    2011-03-01

    The aim of the study was to control occupational exposure during the removal of radioactive reactor components from a Greek research reactor pool. The method comprised the prediction of the radiation levels, the design of special shielding structures and the occupational dose assessment. Activation calculations were performed using the FISPACT code to predict the source term. Monte Carlo simulations using MCNP code were utilized to estimate the ambient dose equivalent rates. The results of the calculations were verified by measurements and were found to be in good agreement. Thermoluminescence dosemeter (TLD) and electronic personal dosemeter (EPD) were implemented to measure the radiation exposure of the workers. The total collective dose of 14 participating workers was 0.15 man mSv. The maximum individual effective dose was 0.02 mSv, and the maximum extremity equivalent dose was 0.09 mSv. The discussed method provides a useful tool enabling work planning during reactor decommissioning and renovation activities ensuring that exposures will be maintained ALARA. PMID:21051436

  8. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    NASA Astrophysics Data System (ADS)

    Caresana, M.; Denker, A.; Esposito, A.; Ferrarini, M.; Golnik, N.; Hohmann, E.; Leuschner, A.; Luszik-Bhadra, M.; Manessi, G.; Mayer, S.; Ott, K.; Röhrich, J.; Silari, M.; Trompier, F.; Volnhals, M.; Wielunski, M.

    2014-02-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  9. Doses to skin during dynamic perfusion computed tomography of the liver.

    PubMed

    Beganovic, Adnan; Sefic-Pasic, Irmina; Skopljak-Beganovic, Amra; Kristic, Spomenka; Sunjic, Svjetlana; Mekic, Amra; Gazdic-Santic, Maja; Drljevic, Advan; Samek, Davorin

    2013-01-01

    Many new computed tomography (CT) techniques have been introduced during the recent years, one of them being CT-assisted dynamic perfusion imaging (perfusion CT, PCT). Many concerns were raised when first cases of deterministic radiation effects were reported. This paper shows how radiochromic films can be utilised as passive dosemeters for use in PCT. Radiochromic dosemeters undergo a colour change directly and do not require chemical processing. Prior to their use, they need to be calibrated. Films are placed on top and on the right side of the patient and exposed during the procedure. Readout is performed using a densitometer. Results show that average local skin doses are 0.510.07 and 0.420.04 Gy on top and on the lateral side of the patient, respectively. Results of the patient dosimetry (local skin doses) are consistent. This is due to the fact that each patient had the same CT protocol used for imaging (120 kV, 60 mA and C(vol) of 247.75 mGy). Radiochromic films designed for interventional radiology can be effectively used for local skin dose measurements in perfusion CT. Dose values obtained are below the threshold needed for deterministic effects (erythema, hair loss, etc.). These effects might happen if inappropriate CT protocol is used; one that is usually used for routine imaging. PMID:22728469

  10. Verification of an effective dose equivalent model for neutrons

    SciTech Connect

    Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.

    1991-10-01

    Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modeling techniques and a knowledge of the radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well-chosen measurements are required to confirm the theoretical models. Neutron measurements were performed in a RANDO phantom using thermoluminescent dosemeters, track etch dosemeters, and a 1/2-in. (1.27-cm) tissue equivalent proportional counter in order to estimate neutron doses and dose equivalents within the phantom at specific locations. The phantom was exposed to bare and D{sub 2}O-moderated {sup 252}Cf neutrons at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and calculate organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared to the calculations. 8 refs., 3 figs., 3 tabs.

  11. Book Review:

    NASA Astrophysics Data System (ADS)

    Burns, J. F.

    1984-01-01

    Publications of the International Commission on Radiation Units and Measurements (ICRU) enjoy a justifiably high reputation for their relevance and accuracy. This is no exception. As the report is assumed to be the joint responsibility of all members of the Commission, no authors' names are given. Nevertheless, the various chapters clearly correspond to the interests of the four members of the "report committee", all of whom are well known in their respective fields of work. The subject of the report is the measurement of absorbed dose and absorbed dose rate in materials exposed to pulsed ionizing radiation, particularly X-ray and electron beams. Only thirty five pages of text may seem at first sight to be insufficient to provide anything but a superficial view of the subject, but the authors have adopted a very compact style which covers a lot of ground. It should be regarded as a practical guide, not as a textbook or scientific monograph; rules are sometimes given without justification, but with a reference to where more information can be found. Four types of radiation detectors are dealt with in separate chapters—ionization chambers, chemical dosemeters, calorimeters and solid-state detectors. For irradiation conditions typical of those encountered in radiotherapy, i.e. from about 0.05 mGy to 1 mGy per pulse, commercial cable-connected ionization chambers are recommended, and this chapter is largely a summary of the many papers by Boag on corrections for non-saturation. Suggestions are also made for the design of chambers for use with higher dose rates up to 100 mGy per pulse. For still higher dose rates, such as those met with in radiobiological and radiochemical research, the Fricke dosemeter can be used up to 10 Gy per pulse. The chapter on chemical dosemeters deals also with extensions upwards in dose rate to about 100 Gy per pulse using "super-Fricke" solution or a thiocyanate dosemeter. Calorimeters are less influenced by a change from continuous to pulsed radiation than are other types of detector, but they do demand fairly high dose rates. Methods to correct for cooling are described in detail, and a warning is given about a possible change in thermal defect of some materials in short pulses with very high instantaneous dose rates. This chapter also contains a useful discussion on monitoring devices. The chapter on solid-state dosemeters covers a wide range of radiation effects including the change of optical absorption in glass and plastic materials after irradiation, photoluminescent and thermoluminescent materials and semiconductor detectors. These devices are described in rather general terms, and there is less information than in other chapters on the special problems of measuring pulsed radiation. The section on semiconductors is now rather out of date as there has been a great increase of interest in these devices in recent years in connection with nuclear hardening of electronic circuits. For those who have to measure protection-level radiation in the vicinity of pulsed accelerators three practical hints are given: don't use particle-counting devices as these will usually just record the pulse repetition frequency of the accelerator (Sect. 2.6), when designing cylindrical and spherical ionization chambers it is wise to avoid the use of a guard ring inside the collecting volume (Sect. 2.7), for large ionization chambers the ion-collection time may be long compared with the period between pulses, and the chamber will then behave as if subjected to continuous rather than pulsed radiation (Sect. 2.2.8). There is no doubt that anyone who is responsible for the dosimetry of pulsed X-ray or electron beams will find this report a handy practical guide and a useful pointer for further information.

  12. Influence of support on the performance of molybdenum sulfide catalysts used to hydrotreat coal liquids

    SciTech Connect

    McCormick, R.L.

    1988-01-01

    Supports for molybdenum sulfide hydrotreating catalysts included silica, silica-magnesia, titania, chromia-alumina, activated carbon and nitrided activated carbon. The alumina supported Amocat 1A and Amocat 1C as well as the silica-alumina supported, Harshaw CoMo-0402 were also studied. Catalysts were characterized by BET surface area, mercury porosimetry and x-ray powder diffraction. Acidity was measured by the temperature programmed desorption of tert-butyl amine. Initial activity screening studies were conducted in a stirred autoclave batch reactor to determine appropriate metals loadings for the various supports. Initially active catalysts were then tested in a bench scale, trickle bed reactor to determine activity maintenance, coking tendency and selectivity at lined out conditions. Selectivities for hydrodenitrogenation and for the production of hydrogen donor molecules were of interest. The donatable hydrogen content of the produce was determined by {sup 1}H and {sup 13}C NMR spectroscopy. The results indicated a strong correlation between lined out hydrogenation activity and the volume in 60-200 {angstrom} diameter pores. A second correlation was observed between HDN activity and acid site density, indicating the importance of acid sites in denitrogenation. Low acidity catalysts appeared to produce a greater hydrogen donor content in the product oil than did high acidity catalysts but the results were not conclusive. The results also suggest that Bronsted acid sites can markedly reduce coking tendency but that in general, coke formation is related in a complex way to the acid/base chemistry of the surface.

  13. Neutron dose measurements with the GSI ball at high-energy accelerators.

    PubMed

    Fehrenbacher, G; Gutermuth, F; Kozlova, E; Radon, T; Schuetz, R

    2007-01-01

    A moderator-type neutron monitor containing pairs of TLD 600/700 elements (Harshaw) modified with the addition of a lead layer (GSI ball) for the measurement of the ambient dose equivalent from neutrons at medium- and high-energy accelerators, is introduced in this work. Measurements were performed with the Gesellschaft für Schwerionenforschung (GSI) ball as well as with conventional polyethylene (PE) spheres at the high-energy accelerator SPS at European Organization for Nuclear Research [CERN (CERF)] and in Cave A of the heavy-ion synchrotron SIS at GSI. The measured dose values are compared with dose values derived from calculated neutron spectra folded with dose conversion coefficients. The estimated reading of the spheres calculated by means of the response functions and the neutron spectra is also included in the comparison. The analysis of the measurements shows that the PE/Pb sphere gives an improved estimate on the ambient dose equivalent of the neutron radiation transmitted through shielding of medium- and high-energy accelerators. PMID:16980706

  14. Rate enhancement for catalytic upgrading coal naphthas. Quarterly progress report, July--September 1992

    SciTech Connect

    Davis, B.H.

    1992-12-31

    During this quarter, hydrotreatment of the Black Thunder naphtha sample was carried out using two commercial catalysts. Also, the Illinois No. 6 naphtha were hydrotreated using unsupported transition metal sulfides. Each reaction condition was maintained for 24 hours and three steady state samples were taken in the last 6 hours of the 24 hours period to calculate the removal of the heteroatoms for each condition. Prior to G.C. analysis, the samples were washed three times with distilled water to remove dissolved H{sub 2}S and NH{sub 3}. Two commercial catalysts, a Co-Mo on alumina (American Cyanamid HDS-1442A, 1/16in. {times} 1/4in. pellets) and a Ni-W on alumina (Harshaw Catalyst, Ni-4301, E 1/12, Lot 16, Drum 29) were employed in the processing of the Black Thunder naphtha samples. Analytical data for these catalysts are presented in Table 1. Unsupported transition metal sulfides were prepared following the procedure published by Chianelli et al.

  15. The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation.

    PubMed

    Nawi, Siti Nurasiah Binti Mat; Wahib, Nor Fadira Binti; Zulkepely, Nurul Najua Binti; Amin, Yusoff Bin Mohd; Min, Ung Ngie; Bradley, David Andrew; Nor, Roslan Bin Md; Maah, Mohd Jamil

    2015-01-01

    Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a (60)Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium. PMID:26307987

  16. Relative thermoluminescent response of LiF-TLD to 252Cf fission fragments

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Kalef-Ezra, J.

    In the framework of our investigations into the use of modified track structure theory (TST) for the calculation of heavy charged particle (HCP) thermoluminescent (TL) yields, we have measured the relative TL response of LiF (Harshaw) to 252Cf fission fragments with the result ηff, α= 1.47 ± 0.34 (TLD-100), 1.25 ± 0.31 (TLD-600) and 1.24 ± 0.28 (TLD-700). The relative TL response at high ionization density is found to be strongly dependent on details of the high temperature annealing procedure and the former results for ηff, α are significantly reduced to 0.58 ± 0.1 (TLD-600, TLD-700) when oxygen-free nitrogen atmosphere and somewhat slower cooling is used during the annealing instead of air. The surprizingly high values of ηff, α obtained for both annealing procedures indicates a definite lack of unique correlation between η and stopping power (˜10 3 and 2 × 10 4 MeV · g-1cm2 for 4 MeV α-particles and 252Cf fission fragments respectively stopping in LiF). On the other hand, modified TST calculations which determine η via a convolution of the charge carrier concentration around the HCP track with the dose-TL response generated from low energy electrons are in good agreement with the experimental results.

  17. Thermoluminescent properties and defect stability in silver doped crystals

    NASA Astrophysics Data System (ADS)

    Mdebuka, A. M.

    1992-03-01

    Thermoluminescence in room-temperature X-irradiated KCl:Ag (14 ppm) crystals has been examined. KCI:Harshaw (nominal pure) crystals are also used for comparison. Stability of defects and kinetics of recombination processes occurring during thermoluminescence are investigated with a closer look at impurity effects. X-irradiations were performed at increasing doses (25 kV and 20 mA, 35 kV and 30 mA, 45 kV and 40 mA) for 5 h at each setting. Results indicate that the stability of defects in Ag-doped samples increases with dose. General-order kinetics methods indicate that recombination processes follow the first-order kinetics since the probability of retrapping (0.01) is far less than that of recombination (0.99). Using several first-order kinetics methods, the frequency factor seem to be in the region associated with escape frequency of electrons (10 9-10 12 s -1).

  18. High-temperature effects on a Co-Mo-Al/sub 2/O/sub 3/ catalyst

    SciTech Connect

    Dale, J.M.; Hulett, L.D.; Fuller, E.L.; Richards, H.L.; Sherman, R.L.

    1980-01-01

    Commercially prepared Harshaw Chemical Co. CoMo-0401 T hydrotreating catalyst was heated in air at 300/sup 0/, 500/sup 0/, 700/sup 0/, 800/sup 0/, 900/sup 0/, and 1000/sup 0/C for 16 hr and studied by X-ray fluorescence, X-ray photoelectron spectroscopy, and electron microscopy. The catalysts heated up to 800/sup 0/C contained the cobalt and molybdenum in separate entities, the latter partly in the form of calcium molybdate at the outer surfaces. At temperatures above 700/sup 0/C, cobalt, molybdenum, silicon, and calcium became mobile, which resulted in uniform distribution of these elements throughout the catalyst and formation of cobalt molybdate and cobalt aluminate coprecipitated with calcium molybdate which segregated from the ..cap alpha..-alumina support. No loss of cobalt or molybdenum was observed to 1000/sup 0/C. The calcium probably originated from a calcium salt of an organic acid binder or from a promoter or stabilizer added in the pellet manufacturing process.

  19. Interim status report of the TMI personnel-dosimetry project

    SciTech Connect

    Rich, B.L.; Alvarez, J.L.; Adams, S.R.

    1981-06-01

    The current 2-chip TLD personnel dosimeter in use at Three Mile Island (TMI) has been shown inadequate for the anticipated high beta/gamma fields during TMI recovery operations in some areas. This project surveyed the available dosimeter systems, set up an Idaho National Engineering Laboratory (INEL) prototype system, and compared this system with those commercial systems that could be made immediately available for comparison. Of the systems tested, the new INEL personnel dosimeter was found to produce the most accurate results for use in recovery operations at TMI-2. The other multiple-chip or multiple-filter systems were found less desirable at present. The most prominent deficiencies in the INEL dosimeter stem from the fact that it lacks a completely automated reader and its x-ray and thermal neutron responses require additional development. A automated prototype reader system may be in operation by the end of CY-1981. Three alternatives for operational dosimetry are discussed. A combination of a modified version of the presently used Harshaw 2-chip dosimeter and the INEL dosimeter is recommended.

  20. Technique For Increasing The Optical Strength Of Single-Crystal NaCI Through Temperature Cycling

    NASA Astrophysics Data System (ADS)

    Franck, Jerome B.; Soileau, MJ

    1982-02-01

    This paper relates a technique for increasing the optical strength of single-crystal NaCl. The 1.06-μm pulse laser-induced damage threshold was increased by a factor of 4.6 by a temperature annealing process. The starting material for this work was single-crystal "laser grade" NaCl acquired from the Harshaw Chemical Company. The bulk laser-induced damage threshold of the crystal was measured prior to and after the heat treatment using a Nd:YAG laser operated at 1.06 pm in the TEM00 spatial mode with a pulse width of 9 nsec, full width at half maximum. After the laser-induced damage threshold of the untreated crystal was meas-ured, it was mounted in a quartz tube and placed in an oven for the heat treatment. The quartz tube was continuously flushed with dry nitrogen throughout the heat treatment. The NaC1 sample was slowly heated to 794°C (approximately 7°C below its melting temperature). The sample was maintained at this temperature for a short time and was then removed from the oven to allow rapid cooling. The specimen required repolishing after the heat treatment because of surface sublimation which occurred at temperatures near melting. After repolishing, the bulk laser-induced breakdown intensity was remeasured and found to be 4.6 times greater than the value measured for the untreated crystal.

  1. Ionic and superionic conductivities of SrF2 crystals in a wide frequency range

    NASA Astrophysics Data System (ADS)

    Evangelakis, G. A.; Miliotis, Demitrios

    1987-09-01

    The ionic and superionic conductivities of SrF2 single crystals purchased from Harshaw have been measured at different temperatures as a function of frequency. The temperature varied from 400 to 1010 °C and the frequency ranged from 10 Hz to 10 MHz. We used a coaxial-line configuration, with polished platinum electrodes welded on stainless steel. At all temperatures the apparent conductivity of the sample depended upon the crystal thickness and the measuring frequency. An analysis has been made using complex-impedance diagrams, which led to the conclusion that the actual conductivity is frequency independent in this temperature range. The observed frequency dependence is attributed to poor contact between the crystal and the electrodes, and this is supported by a model analysis based on an equivalent electric circuit with air-gap capacitance. Therefore no frequency dependence can be deduced for the conductivity of SrF2 crystals. In addition, from the experimental Arrhenius diagram, we calculate extrinsic and intrinsic enthalpies.

  2. Response of thermoluminescent dosimeters to photons simulated with the Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Moralles, M.; Guimarães, C. C.; Okuno, E.

    2005-06-01

    Personal monitors composed of thermoluminescent dosimeters (TLDs) made of natural fluorite (CaF 2:NaCl) and lithium fluoride (Harshaw TLD-100) were exposed to gamma and X rays of different qualities. The GEANT4 radiation transport Monte Carlo toolkit was employed to calculate the energy depth deposition profile in the TLDs. X-ray spectra of the ISO/4037-1 narrow-spectrum series, with peak voltage (kVp) values in the range 20-300 kV, were obtained by simulating a X-ray Philips MG-450 tube associated with the recommended filters. A realistic photon distribution of a 60Co radiotherapy source was taken from results of Monte Carlo simulations found in the literature. Comparison between simulated and experimental results revealed that the attenuation of emitted light in the readout process of the fluorite dosimeter must be taken into account, while this effect is negligible for lithium fluoride. Differences between results obtained by heating the dosimeter from the irradiated side and from the opposite side allowed the determination of the light attenuation coefficient for CaF 2:NaCl (mass proportion 60:40) as 2.2 mm -1.

  3. BGO suppressed gamma detector arrays

    NASA Astrophysics Data System (ADS)

    Tabor, S. L.

    1987-04-01

    Arrays of a number of high-resolution γ detectors are needed to investigate the excited states of nuclei in detail, especially in coincidence experiments. The best elements currently available for such arrays use a high-resolution Ge diode detector surrounded by a high-efficiency Bi 4Ge 3O 12 (BGO) scintillator. The BGO scintillator serves to veto those events in which the incoming γ-ray undergoes Compton scattering leading to escape of the scattered photon from the Ge crystal. The first elements of a detector array at the FSU tandem-linac laboratory have been assembled with Ortec high-purity n-type Ge crystals and single crystal BGO scintillators from Harshaw. Each Ge crystal is placed inside a 127 cm diameter by 152 cm long BGO annulus. A smaller 61 mm diameter by 81 mm long BGO split annulus is placed around the cold finger behind the Ge crystal. The performance of the array elements and repair techniques on the Ge detectors are discussed.

  4. Climax spent fuel dosimetry. Short term exposure, 8 March 1983

    SciTech Connect

    Quam, W.; DeVore, T.

    1984-06-01

    The second short-term exposure (performed 8 March 1983) in Hole CFH3 at the Climax Spent Fuel Test site is described. These short-term (1 hour long) exposures are intended to provide an independent measurement of the exposure rate at the wall and the 0.51-m and 0.66-m locations. Only CaF{sub 2} TLD`s were used in the second short-term exposure. Harshaw chips were cut to 0.32 x 0.18 x 0.09 cm size and aged by several exposure/readout/bakeout cycles until all odd chips were weeded out and the remaining chips exhibited stable sensitivities. Exposure at Climax was done by removing the existing long-term dosimetry strings and inserting identical strings using the CaF{sub 2} TLD`s in the stainless steel holders. The first short-term exposure produced absorbed doses as high as {similar_to}000 rads-LiF. The linearity corrections determined for the CaF{sub 2} TLD`s at these exposure levels were {similar_to}2%. The present post-exposure calibration method used calibration doses very close to those encountered in the field.

  5. The role of organic solvent for liquefaction of biomass into liquid fuels and chemicals

    SciTech Connect

    Datta, B.K.

    1994-12-31

    Five reactions were carried out using the Ni-1404P (HARSHAW) catalyst, in a tetralin medium at 350{degrees}C, 35 bar hydrogen, two hours reaction time and 8:1 solvent/feed ratio, on different feeds in a one liter capacity rocker autoclave reactor. The products recovery from autoclave reactor prior to processing was almost quantitative. Pressures that were measured after cooling the reactor to room temperature were, in general, found to be smaller than the initial pressure used. This indicates the consumption of hydrogen and production of chemicals that are potential alternative sources to fossil fuels for energy production. Therefore, these products were confirmed by IR and GC. High oil yields (liquid product) were obtained from saw-dust> cellulose > straw > refuse. On the other hand, highest char yield (solid product) is refuse > straw > saw-dust > cellulose. Moreover, highest organic liquid products were obtained from cellulose > straw > saw-dust > refuse. Fission of sugar units provides a variety of carbonyl compounds, such as acetaldehyde and glyoxal, which readily evaporate. By condensation of unsaturated products and cleavage of the side chains through a free radical mechanism, there were formed new chemicals due to high temperature and pressure. The role of tetralin in the liquefaction process is discussed.

  6. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al 2O 3:C

    NASA Astrophysics Data System (ADS)

    Mittani, J. C. R.; da Silva, A. A. R.; Vanhavere, F.; Akselrod, M. S.; Yukihara, E. G.

    2007-07-01

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al 2O 3:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with 6Li ( 6LiF), lithium carbonate 95% enriched with 6Li ( 6Li 2CO 3), boric acid enriched with 99% of 10B (H310BO) and gadolinium oxide (Gd 2O 3). The proportion of Al 2O 3:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare 252Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ( 6LiF:Mg,Ti and 7LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al 2O 3:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the 60Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al 2O 3:C.

  7. Thermoluminescence properties of CVD diamond films

    NASA Astrophysics Data System (ADS)

    Pospíil, J.; Bulí, R.; Budinská, Z.; Novák, R.; Sopko, B.; Spváek, V.; Echák, T.; Hlídek, P.; Matjka, P.; Macková, A.; Cejnarová, A.; Krása, J.

    2003-09-01

    Two kinds of CVD diamond films were investigated with respect to their thermoluminescent (TL) properties, especially concerning their sensitivity to ionising radiation and to daylight. The films were characterised by means of Raman/photoluminescence/FTIR spectroscopy, XRD, RBS and elastic recoil detection analysis (ERDA). Thermoluminescent (TL) responses of these materials to photons provided by radionuclide 55Fe source (6 keV) over the dose range from 1 to 100 mGy were measured. Typical TL glowcurve is a result of two components, one with maximum in range 160-180 °C and the second, between 307-327 °C. In irradiated samples, the first peak is caused by the exposure to daylight, which increases overall TL signal, the second is caused by irradiation by ?-photons. Exploitation of TL properties of CVD diamonds for a photon dosimetry is possible after careful daylight shielding. The sensitivity of used CVD diamond dosimeters was 10 times less than that of TLD 100 (LiF: Mg, Ti) Harshaw dosimeter. (

  8. Automated hydrotreating pilot plants

    SciTech Connect

    Yanik, S.J.; Graham, J.R.

    1986-03-01

    One of the major tasks facing catalyst supplies involved in hydrotreating/hydrogenation catalyst development work is proper catalyst evaluation. There are dozens of hydrotreating catalysts available to refiners, and selecting the optimum catalyst for a particular application is a challenging task. For fixed bed applications, the choice is especially difficult because, in addition to activity and selectivity, both catalyst life and pressure drop buildup are important considerations. Unfortunately, data on these latter effects are seldom available for new catalyst formulations. While pilot-plant data have been proven to be reliable indicators of the ultimate catalyst life achieved commercially, long-term catalyst aging data are expensive to gather, and proper pilot-plant design is mandatory to duplicate commercial results. Because the proper catalyst choice can earn millions of dollars per year for refiners in terms of enhanced downstream product values, it is justified to install top-quality pilot-plant facilities to demonstrate these benefits. This article describes an automated, minimum-attention set of five state-of-the-art hydrotreating pilot plants that are being completed for the Filtrol Catalyst Division of the Harshaw/Filtrol Partnership.

  9. Mixed-radiation discrimination using thermoluminescent dosimeters

    NASA Astrophysics Data System (ADS)

    Skopec, Marlene

    This work has developed, analyzed, and tested methods to discriminate among different types of radiation exposures using the glow curves of thermoluminescent dosimeters (TLDs). Thermoluminescent materials, Harshaw LiF:Mg,Ti (TLD-100) and CaF2:Tm (TLD-300), were exposed to pure proton, pure photon (x-ray and gamma), and mixed fields to examine and use differences in the thermoluminescent (TL) glow curve shapes for the purpose of radiation type discrimination. The effect of radiation type exposure order on thermoluminescent glow curve shape and the principle of superposition of glow curves were evaluated. Using computerized glow curve deconvolution (CGCD), no significant differences in glow curve shape or magnitude were found. Results demonstrated that the superposition of pure field glow curves is a valid method of simulating mixed field glow curves (i.e., the principle of superposition holds). Two robust and novel techniques for radiation type discrimination were developed: vector representation (VR) and principal component analysis (PCA). In VR, vectors were constructed from glow curve points and classified based on the vector inner product with a unit vector and vector magnitude. In PCA, variations in the glow curves due to radiation type are classified according to one principal component. The two methods were tested for accuracy using leave-one-out validation (LOOV) with classification based on the Mahalanobis distance. Overall, both techniques performed equally well, with over 92% accurate three category classification using the high temperature peak of TLD-100 and nearly 100% correct classification in TLD-300.

  10. Investigation of the use of Ge-doped optical fibre for in vitro IMRT prostate dosimetry

    NASA Astrophysics Data System (ADS)

    Noor, Noramaliza M.; Hussein, M.; Bradley, D. A.; Nisbet, A.

    2011-10-01

    In this study, the thermoluminescence (TL) yield of Ge-doped optical fibres for in vitro dosimetry has been investigated for the verification of Intensity Modulated Radiation Therapy (IMRT) three-dimensional (3D) dose distributions. Ge-doped optical fibres offer many advantages over conventional dosimetry systems including high sensitivity, minimal fading, and cost effectiveness. IMRT verification plans using the Varian Eclipse treatment planning system for two prostate cancer patients were created using Alderson Rando Anthropomorphic Phantom CT data-sets. Measurements were performed using the Rando phantom at nominal energies of 6 MV and 15 MV. Ge-doped optical fibre TL yields were compared with dose determined through use of the treatment planning system and also with the well-established TL lithium fluoride (LiF) dosimetry system (Harshaw TLD-100 and TLD-700). Results show the Ge-doped optical fibre to verify in vitro doses within 3% of the Eclipse predicted doses and LiF TLDs for the particular high energy photon beams used.

  11. Catalytic hydrogenation of coal-derived liquids. Interim report, March-May 1981

    SciTech Connect

    Berg, L.; McCandless, F.P.

    1981-07-01

    Two runs of more than 100 hours of catalyst life were completed using SRC-I and SRC-II as the feeds. One run had catalyst regeneration every three hours, the other every eight hours. The catalyst, 4% CoO, 8% MoO/sub 3/, 1% NiO and 8% WO/sub 3/ on NALCO-78-6008C alumina base, reduced the nitrogen content to less than 0.3% and showed no signs of deterioration in activity. Regeneration after the three or eight hour periods was by burnoff with oxygen in nitrogen followed by re-sulfiding with H/sub 2/S in hydrogen. The liquid yield from SRC was 90% of which 30% was 50 to 204/sup 0/C. boiling range gasoline. It appears that a viable process to convert SRC into a feedstock acceptable to a petroleum refinery has been discovered. A study of the effect of carbon laydown on pore volume and subsequent deactivation of the catalyst was carried out in a pressurized batch reactor. Little reduction in pore volume was noted. Three commercial catalysts, Harshaw HT400, NALCO MO477 and NALCO MN502, were evaluated with SRC-II. These catalysts are capable of giving specification grade denitrogenation for up to five hours. The effect of added water to the feed stream lengthened the cycle time for the HT400 catalyst. About 25% of the liquid product is in gasoline boiling range.

  12. In vivo evaluating skin doses for lung cancer patients undergoing volumetric modulated arc therapy treatment.

    PubMed

    Tseng, Hsien-Chun; Pan, Lung-Kang; Chen, Hsin-Yu; Liu, Wen-Shan; Hsu, Chang-Chieh; Chen, Chien-Yi

    2015-01-01

    This study is the first to use 10- to 90-kg tissue-equivalent phantoms as patient surrogates to measure peripheral skin doses (Dskin) in lung cancer treatment through Volumetric Modulated Arc Therapy of the Axesse linac. Five tissue-equivalent and Rando phantoms were used to simulate lung cancer patients using the thermoluminescent dosimetry (TLD-100H) approach. TLD-100H was calibrated using 6 MV photons coming from the Axesse linac. Then it was inserted into phantom positions that closely corresponded with the position of the represented organs and tissues. TLDs were measured using the Harshaw 3500 TLD reader. The ICRP 60 evaluated the mean Dskin to the lung cancer for 1 fraction (7 Gy) undergoing VMAT. The Dskin of these phantoms ranged from 0.51±0.08 (10-kg) to 0.22±0.03 (90-kg) mSv/Gy. Each experiment examined the relationship between the Dskin and the distance from the treatment field. These revealed strong variations in positions close to the tumor center. The correlation between Dskin and body weight was Dskin (mSv) = -0.0034x + 0.5296, where x was phantom's weight in kg. R2 is equal to 0.9788. This equation can be used to derive an equation for lung cancer in males. Finally, the results are compared to other published research. These findings are pertinent to patients, physicians, radiologists, and the public. PMID:26405934

  13. Hydrotreating for re-refined lubricating oil. Final technical report. [HDS-20A (Al/sub 2/O/sub 3/ with CoO and MoO/sub 3/); HT-500 (Al/sub 2/O/sub 3/ with NiO and MoO/sub 3/)

    SciTech Connect

    Wilson, D.B.

    1981-01-01

    The BERC Process for re-refining lubricating oil uses hydrotreating as a process step in place of a conventional acid-clay operatin. While hydrotreating is a well-established unit process for petroleum and many other liquid hydrocarbons, very little experimental work is available on re-refined lubricating oil. Eight commercial hydrotreating catalysts were screened over the temperature range of 550 to 750/sup 0/F and over the pressure range of 500 psig to 700 psig. These materials were tested in a Autoclave spinning-basket reactor using a liquid hourly weight space velocity (LHWSV) of approximately 8.0 cc/gm.cat.hr. and hydrogen flow sufficient to maintain saturated liquid. Using color change (sulfur wt %) and viscosity (both 100/sup 0/ and 210/sup 0/F) as the measure of catalysts performance, two catalysts-American Cyanamide HDS-20A and Harshaw HT-500 were selected for trickle-bed operation experiments. The HDS-20A and HT-500 catalysts were operated in a trickle-bed reactor system for 238 hours and 407 hours, respectively. The results of these experiments were correlated in terms of the weight percent sulfur present as a function of temperature and pressure of operation and the LHWSV. Initial examination of the catalysts after the trickle-bed experiments showed residual hydrocarbons on the surface. Washing with acetone removed substantially all this residual material. Elemental analysis of the remaining material showed carbon. 47 figures, 28 tables.

  14. The track interaction model for alpha particle induced thermoluminescence supralinearity: dependence of the supralinearity on the vector properties of the alpha particle radiation field

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Rosenkrantz, M.; Mahajna, S.; Yossian, D.

    1996-01-01

    Thermoluminescence (TL) - fluence response characteristics for peaks 5, 7, 8 and 9 in LiF:Mg,Ti (TLD-100; Harshaw/Bicron) were measured for 5 MeV alpha particles, in both `non-parallel' and `near-parallel' geometries,and for 1 MeV alpha particles in `near-parallel' geometry. The onset of supralinearity in the non-parallel configuration is always at a significantly lower fluence (by approximately a factor of five) than in the nearly parallel configuration. This dependence of the onset of supralinearity on the vector properties of the alpha particle radiation field is interpreted as `proof positive' of the dominant importance of track interaction effects in the linear/supralinear behaviour of the glow peaks of TLD-100. A mathematical expression for the linear/supralinear behaviour for heavy charged particles in near-parallel geometry has been developed and fitted to the TL - fluence response curves. The model incorporates both possibilities of electron and hole diffusion in the glow curve heating stage as well as the contribution to the supralinearity of all the participating nearest-neighbour track interactions. The model is capable of yielding excellent fits to the experimental data; the inclusion of hole diffusion and retrapping is preferred to predict the very abrupt transition from linear to supralinear behaviour for the high-temperature peaks.

  15. A TLD dose algorithm using artificial neural networks

    SciTech Connect

    Moscovitch, M.; Rotunda, J.E.; Tawil, R.A.; Rathbone, B.A.

    1995-12-31

    An artificial neural network was designed and used to develop a dose algorithm for a multi-element thermoluminescence dosimeter (TLD). The neural network architecture is based on the concept of functional links network (FLN). Neural network is an information processing method inspired by the biological nervous system. A dose algorithm based on neural networks is fundamentally different as compared to conventional algorithms, as it has the capability to learn from its own experience. The neural network algorithm is shown the expected dose values (output) associated with given responses of a multi-element dosimeter (input) many times. The algorithm, being trained that way, eventually is capable to produce its own unique solution to similar (but not exactly the same) dose calculation problems. For personal dosimetry, the output consists of the desired dose components: deep dose, shallow dose and eye dose. The input consists of the TL data obtained from the readout of a multi-element dosimeter. The neural network approach was applied to the Harshaw Type 8825 TLD, and was shown to significantly improve the performance of this dosimeter, well within the U.S. accreditation requirements for personnel dosimeters.

  16. Position-sensitive detectors of the detector group at Jülich

    NASA Astrophysics Data System (ADS)

    Engels, R.; Clemens, U.; Kemmerling, G.; Nöldgen, H.; Schelten, J.

    2009-06-01

    The detector group of the Central Institute of Electronics at the Forschungszentrum Jülich GmbH was founded in 1968. First developments aimed at a detector system with a position-sensitive BF 3 proportional counter for small-angle neutron scattering, which was later used at a beamline of the research reactor FRJ2. At the end of the 1970s first measurements were carried out with photomultiplier (PM)-based detector systems linked with a LiI crystal from Harshaw. Based on this experience we started with the spectrum of position-sensitive neutron scintillation detectors, which have been developed and designed in our institute during the last three decades comprising several high-resolution linear and two-dimensional detectors. The general design of those detectors is based on a modified Anger principle using an array of PMs and a 1 mm 6Li glass scintillator. The sensitive detector area varies on the type of the PMs used and is related to the spatial resolution of the detector type. The neutron sensitivity at 1 Å is about 65% and the remaining gamma sensitivity is less than 10 -4 with a maximum count rate up to 500 kHz depending on the used detector system.

  17. An investigation of the deactivation phenomena associated with the use of commercial HDS catalysts

    SciTech Connect

    Ammus, J.M.; Androutsopoulos, G.P.; Tsetsekou, A.H.

    1987-07-01

    Catalyst deactivation data, obtained from the HDS of a Greek oil residue on a spinning basket laboratory scale reactor, are reported in this paper. Two commercial grade hydrodesulfurization (HDS) catalysts, viz., Harshaw HT-400 E and ICI-41-6, were used in the investigation. Initial activities and modes of activity loss vs. run time are compared (HT-400 E possessed an initial activity 25% higher than that of ICI-41-6; activity was reduced to 55-65% for the former and 70% for the latter catalyst after 100 h of operation). Coke and metal deposits built up vs. run time are also reported here (75% of the total amount was deposited within the initial 30 h of catalyst operation. The role of catalyst particle size upon the rate and the extent of activity reduction is quantified. Experimental data showing the dependence of the catalyst pellet coke content vs. the nominal coke deposit thickness were fitted by using a random corrugated pore model, and the effect of particle size was satisfactorily quantified.

  18. Thermoluminescence characteristics of flat optical fiber in radiation dosimetry under different electron irradiation conditions

    NASA Astrophysics Data System (ADS)

    Alawiah, A.; Intan, A. M.; Bauk, S.; Abdul-Rashid, H. A.; Yusoff, Z.; Mokhtar, M. R.; Wan Abdullah, W. S.; Mat Sharif, K. A.; Mahdiraji, G. A.; Mahamd Adikan, F. R.; Tamchek, N.; Noor, N. M.; Bradley, D. A.

    2013-05-01

    Thermoluminescence (TL) flat optical fibers (FF) have been proposed as radiation sensor in medical dosimetry for both diagnostic and radiotherapy applications. A flat optical fiber with nominal dimensions of (3.226 × 3.417 × 0.980) mm3 contains pure silica SiO2 was selected for this research. The FF was annealed at 400°C for 1 h before irradiated. Kinetic parameters and dosimetric glow curve of TL response were studied in FF with respect to electron irradiation of 6 MeV, 15 MeV and 21 MeV using linear accelerator (LINAC) in the dose range of 2.0-10.0 Gy. The TL response was read using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader used includes; initial preheat temperature of 80°C, maximum readout temperature is 400°C and the heating rate of 30°Cs-1. The proposed FF shows excellent linear radiation response behavior within the clinical relevant dose range for all of these energies, good reproducibility, independence of radiation energy, independence of dose rate and exhibits a very low thermal fading. From these results, the proposed FF can be used as radiation dosimeter and favorably compares with the widely used of LiF:MgTi dosimeter in medical radiotherapy application.

  19. Dosimetric properties of the newly developed KLT-300 (LiF:Mg,Cu,Na,Si) TL detector.

    PubMed

    Lee, J I; Kim, J L; Chang, S Y; Chung, K S; Choe, H S

    2004-01-01

    The dosimetric properties of the newly developed KLT-300 (KAERI LiF:Mg,Cu,Na,Si TL detector) in KAERI (Korea Atomic Energy Research Institute) were investigated. The sensitivity of the TL detector was about 30 times higher than that of the TLD-100 by light integration. In the study of the dose linearity of the detector, the dose response was very linear up to 10 Gy and a sublinear response was observed at higher doses. The energy response of the detector was studied for photon energies from 20 to 662 keV. The results show that a maximum response of 1.004 at 53 keV and a minimum response of 0.825 at 20 keV were observed. The reproducibility study for the TL detector was also carried out. The coefficients of variation for each detector separately did not exceed 0.016, and for all the 10 detectors collectively it was 0.0054. IEC Standard requires that the coefficient of variation shall not exceed 0.075. So, the reproducibility of this new TL detector sufficiently satisfied the IEC requirements. A detection threshold of the detector was investigated and found to be 70 nGy by Harshaw 4500 TLD Reader. PMID:15856584

  20. Pore structure characterization of catalyst supports via low field NMR

    SciTech Connect

    Smith, D.M.; Glaves, C.L.; Gallegos, D.P. )

    1988-09-01

    The pore structures of two types of catalyst support material were studied: {gamma}-alumina and silica aerogel. The alumina samples were commercial catalyst supports made in 1/8 inch diameter pellet form by Harshaw Chemical. Aerogels were prepared by forming a gel in a two-step, base-catalyzed process using TEOS, followed by supercritical drying to form the aerogel. Two different aerogels were made, one undergoing the drying process immediately after gel formation (non-aged), and the other being aged in the gel state for two weeks in a basic solution of 0.1 molar NH{sub 4}OH at 323 K before being supercritically dried (aged). The aging process is believed to alter the aerogel pore structure. The pore size distribution of the alumina material was determined via NMR and compared to results obtained by mercury intrusion and nitrogen adsorption/condensation techniques. The pore size distributions of the two aerogel samples were measured via NMR and nitrogen adsorption/condensation; the material was too compressible for porosimetry.

  1. Optical modeling of black chrome solar-selective coatings

    NASA Astrophysics Data System (ADS)

    Sweet, J. N.; Pettit, R. B.

    1982-07-01

    Various investigations of coating microstructure are reviewed and the results of these studies are used to develop a picture of the microstructure of the black chrome films plated from the Harshaw Chromonyx bath. In this model, the black chrome film is composed of roughly spherical particles which may tend to cluster together. These particles in turn are composed of small crystallites of metallic chrome and various oxides of chrome. The film void volume fraction appears to be or = 0.6. The microstructural picture has been idealized to facilitate calculations of the spectral reflectance for films deposited onto nickel substrates and for freestanding or stripped films. In the idealized model, the metallic chromium is assumed to be in the form of spherical crystallites with concentric shells Cr2O3 and the crystallite volume fraction is assumed to increase with depth into the film. Various experimental data are utilized to define film thickness, average volume fraction of Cr + Cr2O3, and volume ratio of Cr to Cr + Cr2O3.

  2. Theoretical and Practical Implications of the Effects of Temperature during Irradiation and during Pre - and Post-Irradiation Storage on the Response of Thermoluminescence Dosimeters.

    NASA Astrophysics Data System (ADS)

    de Planque, E. Gail

    Experiments have been conducted to determine the applicability of the Randall-Wilson theory for describing the behavior of CaF(,2):Mn thermoluminescence dosimeters (Harshaw TLD-400 chips). Results were obtained for four different conditions: irradiation followed by storage, irradiation after storage, irradiation both preceded and followed by storage, and continuous simultaneous irradiation and storage. The experiments were performed for storage intervals of approximately 1, 2, 3, 5, 6 and 7 days at five different storage temperatures: -25, +20, +65, +150 and +175(DEGREES)C. The results indicate fading that is described not by the Randall-Wilkins theory but rather as a function of the logarithm of the storage time. While the results suggest that the trapping efficiency is independent of temperature, they do demonstrate a small decrease in TL response with storage time prior to irradiation which is independent of temperature and time (> 17 hours) and hence probably not dosimetric in origin but perhaps optically related. Glow curve analyses support the concept of a band of traps rather than a single trap. The overall results are compared to other data available in the literature most of which is for room-temperature storage. These data, show remarkably good agreement when uniformly normalized. Although peripheral experiments revealed problems associated with self-irradiation as well as a decline in sensitivity with use, the stability experiment results verify the highly favorable stability properties of CaF(,2):Mn for common widespread application.

  3. An example of abnormal glow curves identification in personnel thermoluminescent dosimetry.

    PubMed

    Osorio Piniella, V; Stadtmann, H; Lankmayr, E

    2002-01-01

    The personal Dosimetry Service Seibersdorf analyses monthly a large number of thermoluminescent dosimeters (TLD). The dosimeters consist of LiF chips, and the readout is carried out with an automated Harshaw 8800 reader system. In some cases, the luminescent glow curves of the routine analysis do not have the expected form as a result of external chemical contamination, hardware problems, poor heat transfer, etc. It is therefore necessary to investigate the reasons for the irregularity of these curves. An algorithm for the investigation of the routine curves was developed. It is based on the fact that the shape of an abnormal glow curve differs from the shape of a normal one. An interesting type of abnormal glow curves in the routine service was found. Some dosimeters of a certain client, a steel industry, exhibit glow curves with an atypical shape and very high signals. In those dosimeters, a possible chemical contamination in the form of a powder was discovered, which interferes with the dosimetric signal. A quantitative analysis of that powder was made by means of inductively coupled plasma emission spectroscopy (ICP-OES) after microwave dissolution. Elements like aluminium, barium, calcium and others were found. Such elements are used in different combinations as thermoluminescent materials. PMID:12406593

  4. An extended role for thermoluminescent phosphors in personnel environmental and accident dosimetry using sensitisation, re-estimation and fast fading

    NASA Astrophysics Data System (ADS)

    Charles, M. W.

    1983-02-01

    This paper summarises some techniques for extending the usefulness of conventional phosphors in personnel, environmental and accident dosimetry. An optimised procedure for utilising radiation sensitisation and UV re-estimation in thermoluminescent LiF is presented. In particular it is shown that optimum performance is achieved by using a UV wavelength of 250 ± 10 nm for both the UV/thermal anneal following sensitisation, and for the UV re-estimation procedure. In the case of Harshaw LiF chips (3×3×0.9 mm 3) the sensitivity is increased by a factor of 4-5 to achieve a minimum detectable dose of ˜ 10 μGy (2 σ) and a minimum re-estimable dose of 50-100 mGy (2σ), dependent on batch. Sensitized LiF also exhibits improved tissue equivalence, extended linearity and improved precision at low doses. The information from fast-fading glow peaks, which is normally rejected, is shown to have a useful application to the evaluation of short-term increases in environmental dose rates such as may occur following accidental releases of radioactivity.

  5. A phantom study of image quality versus radiation dose for digital radiography

    NASA Astrophysics Data System (ADS)

    Tung, C. J.; Tsai, H. Y.; Shi, M. Y.; Huang, T. T.; Yang, C. H.; Chen, I. J.

    2007-09-01

    In the present work, a contrast-detail phantom was used to study the image quality and the radiation dose for digital X-ray imaging systems. The phantom consists of a 265 mm (H)×265 mm (W)×10 mm (D) acrylic sheet with drilled holes of various depths and diameters. At each setting of exposure techniques, three images were taken and evaluated subjectively by three independent radiologists. The average image quality figure (IQF) was then calculated. In addition, a computer program was developed to evaluate objectively the same images. This program, written in MATLAB, was based on a statistical method with variance analysis of the image pixels. Corrections of the parallax effect were made. Results showed that the computer program proved more sensitive than the radiologists. In addition to image analyses, the entrance surface dose (ESD) was measured using the Harshaw thermoluminescent dosimeters TLD-100H. Two 75 mm-thick acrylic slabs were used with the contrast-detail phantom in between. Optimization analyses on the image quality and the radiation dose were performed.

  6. The development, characterization, and performance evaluation of a new combination type personnel neutron dosimeter

    SciTech Connect

    Liu, J.C.; Sims, C.S.; Poston, J.W.; Texas A and M Univ., College Station, TX . Dept. of Nuclear Engineering)

    1989-10-01

    A new combination type personnel neutron dosimeter has been designed and developed at the Oak Ridge National Laboratory (ORNL). The combination personnel neutron dosimeter (CPND) consists of a Harshaw albedo neutron thermoluminescent dosimeter (two pairs of TLD-600/TLD- 700) and two bubble detectors (one BD-100R and one BDS-1500 from Bubble Technology Industries, Canada). The CPND was developed with the aim of having crude neutron spectrometric capability, universal applicability, better angular response, and an improved lower limit of detection (LLD). The CPND has been well characterized in the following areas: reusability, linearity, lower limit of detection (LLD), detection capability in mixed neutron-gamma fields, angular dependence, and neutron energy dependence. the characterization was accomplished with irradiations using a {sup 238}Pu-Be source, a {sup 252}Cf(D{sub 2}O) source, a {sup 252}Cf source, a {sup 252}Cf(PE) source, monoenergetic neutrons from accelerator and reactor filtered beams, {sup 137}Cs, and X-rays. Optimum signal readout procedures, signal processing techniques, routine operational usage, and neutron dose equivalent evaluation algorithms for the CPND were developed with the goals of having the best precision and accuracy as well as being convenient to use. 97 refs., 43 figs., 22 tabs.

  7. Rate enhancement for catalytic upgrading coal naphthas

    SciTech Connect

    Davis, B.H.

    1992-01-01

    During this quarter, hydrotreatment of the Black Thunder naphtha sample was carried out using two commercial catalysts. Also, the Illinois No. 6 naphtha were hydrotreated using unsupported transition metal sulfides. Each reaction condition was maintained for 24 hours and three steady state samples were taken in the last 6 hours of the 24 hours period to calculate the removal of the heteroatoms for each condition. Prior to G.C. analysis, the samples were washed three times with distilled water to remove dissolved H[sub 2]S and NH[sub 3]. Two commercial catalysts, a Co-Mo on alumina (American Cyanamid HDS-1442A, 1/16in. [times] 1/4in. pellets) and a Ni-W on alumina (Harshaw Catalyst, Ni-4301, E 1/12, Lot 16, Drum 29) were employed in the processing of the Black Thunder naphtha samples. Analytical data for these catalysts are presented in Table 1. Unsupported transition metal sulfides were prepared following the procedure published by Chianelli et al.

  8. Studies involving high temperature desulfurization/regeneration reactions of metal oxides for fuel cell development. Project status report, June 1982

    SciTech Connect

    Not Available

    1982-07-15

    Desulfurization/regeneration tests of V/sub 2/O/sub 5/ supported on alumina prepared at Giner, Inc., Harshaw Vanadia catalyst obtained from METC and unsupported high purity V/sub 2/O/sub 5/ (Union Carbide) were carried out in a new quartz lined reactor. The results obtained are similar to those obtained in the previously used stainless steel reactor. Figure 1 and 2 confirm that V/sub 2/O/sub 3/ has an affinity to react with H/sub 2/S. The vanadia catalyst obtained from METC showed lower sulfur capacity than the one obtained directly. It is seen that change in desulfurization temperature has little effect on sulfur capacity (Figure 1), but the change in water concentration of inlet gas mixture has a large effect on sulfur capacity (Figure 2). Both of these results are in agreement with our earlier experiments. Surface analyses of mixed oxide CuO/ZnO, CuO/zeolite and CuO/Al/sub 2/O/sub 3/ sorbents were carried out by Scanning Eletron Microscopy (SEM). Procurement of quartz reactor, furnace and other accessories and construction of fluidized bed reactor systems have progressed well.

  9. Pilot Quality Control Program for Brachytherapy of Low Dose Rate at the General Hospital of Mexico

    NASA Astrophysics Data System (ADS)

    Álvarez R., J. T.; Tovar M., V.; Salinas, B.; Hernández O., O.; Santillán B., L.; Molero M., C.; Montoya M., J.

    2004-09-01

    We describe the pilot quality control program for brachytherapy of low dose rate proposed to be used in the Radiotherapy Department at the General Hospital of Mexico. The program consists of three parts: a) development of calibration procedures, performed in terms of air-kerma strength for calibration of 137Cs and 192Ir brachytherapy sources, and for the calibration of well-type ionization chambers for 137Cs, b) performance of localisation and reconstruction techniques for radioactive sources with a Baltas' phantom. The results obtained for the media deviation , are in the optimum level, ± 0.5 mm < ± 1.0 mm; the confidence limit Δ, is in the emergency level, Δ=3.2 mm. c) verification of absorbed dose to water DW, given by the hospital. It consists on the characterisation of a TLD-100 powder dosimetry system at SSDL: The calibration curves for powder response (nC or nC/ mg) vs Dw and the control charts for the Harshaw 3500 reader were obtained. The statistical validation of the calibration curve by normality of the residuals and the lack of fit tests were realised. In the other hand, TLD's were irradiated in the hospital to a nominal Dw = 2 Gy with sources of 137Cs. The percent deviations Δ%, between the Dw imparted by the Hospital and the determined by SSDL, are 1.2% Δ⩽ 6.5 % which are consistent with the expanded uncertainty U% for DW, 5.6 U% 10%.

  10. TLD postal dose intercomparison for megavoltage units in Poland.

    PubMed

    Izewska, J; Gajewski, R; Gwiazdowska, B; Kania, M; Rostkowska, J

    1995-08-01

    The aim of the TLD pilot study was to investigate and to reduce the uncertainties involved in the measurements of absorbed dose and to improve the consistency in dose determination in the regional radiotherapy centres in Poland. The intercomparison was organized by the SSDL. It covered absorbed dose measurements under reference conditions for Co-60, high energy X-rays and electron beams. LiF powder type MT-N was used for the irradiations and read with the Harshaw TLD reader model 2000B/2000C. The TLD system was set up and an analysis of the factors influencing the accuracy of absorbed dose measurements with TL-detectors was performed to evaluate and minimize the measurement uncertainty. A fading not exceeding 2% in 12 weeks was found. The relative energy correction factor did not exceed 3% for X-rays in the range 4-15 MV, and 4% for electron beams between 6 and 20 MeV. A total of 34 beams was checked. Deviation of +/- 3.5% stated and evaluated dose was considered acceptable for photons and +/- 5% for electron beams. The results for Co-60, high energy X-rays and electron beams showed that there were two, three and no centres, respectively, beyond acceptance levels. The sources of errors for all deviations out of this range were thoroughly investigated, discussed and corrected, however two deviations remained unexplained. The pilot study resulted in an improvement of the accuracy and consistency of dosimetry in Poland. PMID:7501812

  11. Calibration of a TLD-100 powder dosimetric system to verify the absorbed dose to water imparted by 137Cs sources in low dose rate brachytherapy at the oncology unit in the Hospital General de Mexico.

    PubMed

    Alvarez Romero, J T; Tovar Muñoz, V M; de León, B Salinas; Oviedo, J O Hernández; Barcenas, L Santillán; Milo, C Molero; Monterrubio, J Montoya

    2006-01-01

    A thermoluminescence dosimetry (TLD) system was characterised at SSDL-ININ to verify the air-kerma strength (S(K)) and dose-to-water (D(W)) values for (137)Cs sources used in low dose rate (LDR) brachytherapy treatments at the Hospital General de Mexico (HGM). It consists of a Harshaw 3500 reader and a set of TLD-100 powder capsules. The samples of TLD-100 powder were calibrated in terms of D(W) vs. nC or nC mg(-1), and their dose response curves were corrected for supralinearity. The D(W) was calculated using the AAPM TG-43 formalism using S(K) for a CDCSM4 (137)Cs reference source. The S(K) value was obtained by using a NE 2611 chamber, and with two well chambers. The angular anisotropy factor was measured with the NE 2611 chamber for this source. The HGM irradiated TLD-100 powder capsules to a reference dose D(W) of 2 Gy with their (137)Cs sources. The percent deviations between the imparted and reference doses were 1.2% < or = Delta < or = 6.5%, which are consistent with the combined uncertainties: 5.6% < or = u(c) < or = 9.8% for D(W). PMID:16644958

  12. Final Harvest of Above-Ground Biomass and Allometric Analysis of the Aspen FACE Experiment

    SciTech Connect

    Mark E. Kubiske

    2013-04-15

    The Aspen FACE experiment, located at the US Forest Service Harshaw Research Facility in Oneida County, Wisconsin, exposes the intact canopies of model trembling aspen forests to increased concentrations of atmospheric CO2 and O3. The first full year of treatments was 1998 and final year of elevated CO2 and O3 treatments is scheduled for 2009. This proposal is to conduct an intensive, analytical harvest of the above-ground parts of 24 trees from each of the 12, 30 m diameter treatment plots (total of 288 trees) during June, July & August 2009. This above-ground harvest will be carefully coordinated with the below-ground harvest proposed by D.F. Karnosky et al. (2008 proposal to DOE). We propose to dissect harvested trees according to annual height growth increment and organ (main stem, branch orders, and leaves) for calculation of above-ground biomass production and allometric comparisons among aspen clones, species, and treatments. Additionally, we will collect fine root samples for DNA fingerprinting to quantify biomass production of individual aspen clones. This work will produce a thorough characterization of above-ground tree and stand growth and allocation above ground, and, in conjunction with the below ground harvest, total tree and stand biomass production, allocation, and allometry.

  13. Geochemistry of soils from the San Rafael Valley, Santa Cruz County, Arizona

    USGS Publications Warehouse

    Folger, Helen W.; Gray, Floyd

    2013-01-01

    This study was conducted to determine whether surficial geochemical methods can be used to identify subsurface mineraldeposits covered by alluvium derived from surrounding areas. The geochemical investigation focused on an anomalous geo-physical magnetic high located in the San Rafael Valley in Santa Cruz County, Arizona. The magnetic high, inferred to be asso-ciated with a buried granite intrusion, occurs beneath Quaternary alluvial and terrace deposits. Soil samples were collected at a depth of 10 to 30 centimeters below land surface along transects that traverse the inferred granite. The samples were analyzed by inductively coupled plasma-mass spectrometry and by the partial-leach Mobile Metal Ion method. Principal component and factor analyses showed a strong correlation between the soils and source rocks hosting base-metal replacement deposits in the Harshaw and Patagonia Mining Districts. Factor analysis also indicated areas of high metal concentrations associated with the Meadow Valley Flat. Although no definitive geochemical signature was identified for the inferred granite, concentrations otungsten and iron in the surrounding area were slightly elevated.

  14. Dosimetric properties of dysprosium doped calcium magnesium borate glass subjected to Co-60 gamma ray

    NASA Astrophysics Data System (ADS)

    Omar, R. S.; Wagiran, H.; Saeed, M. A.

    2016-01-01

    Thermoluminescence (TL) dosimetric properties of dysprosium doped calcium magnesium borate (CMB:Dy) glass are presented. This study is deemed to understand the application of calcium as the modifier in magnesium borate glass with the presence of dysprosium as the activator to be performed as TL dosimeter (TLD). The study provides fundamental knowledge of a glass system that may lead to perform new TL glass dosimetry application in future research. Calcium magnesium borate glass systems of (70-y) B2O3 - 20 CaO - 10 MgO-(y) Dy2O3 with 0.05 mol % ≤ y ≤ 0.7 mol % of dyprosium were prepared by melt-quenching technique. The amorphous structure and TL properties of the prepared samples were determined using powder X-ray diffraction (XRD) and TL reader; model Harshaw 4500 respectively. The samples were irradiated to Co-60 gamma source at a dose of 50 Gy. Dosimetric properties such as annealing procedure, time temperature profile (TTP) setting, optimization of Dy2O3 concentration of 0.5 mol % were determined for thermoluminescence dosimeter (TLD) reader used.

  15. The Thermoluminescence Response of Ge-Doped Flat Fibers to Gamma Radiation

    PubMed Central

    Mat Nawi, Siti Nurasiah Binti; Wahib, Nor Fadira Binti; Zulkepely, Nurul Najua Binti; Amin, Yusoff Bin Mohd; Min, Ung Ngie; Bradley, David Andrew; Md Nor, Roslan Bin; Maah, Mohd Jamil

    2015-01-01

    Study has been undertaken of the thermoluminescence (TL) yield of various tailor-made flat cross-section 6 mol% Ge-doped silica fibers, differing only in respect of external dimensions. Key TL dosimetric characteristics have been investigated, including glow curves, dose response, sensitivity, fading and reproducibility. Using a 60Co source, the samples were irradiated to doses within the range 1 to 10 Gy. Prior to irradiation, the flat fibers were sectioned into 6 mm lengths, weighed, and annealed at 400 °C for 1 h. TL readout was by means of a Harshaw Model 3500 TLD reader, with TLD-100 chips (LiF:Mg, Ti) used as a reference dosimeter to allow the relative response of the fibers to be evaluated. The fibers have been found to provide highly linear dose response and excellent reproducibility over the range of doses investigated, demonstrating high potential as TL-mode detectors in radiation medicine applications. Mass for mass, the results show the greatest TL yield to be provided by fibers of the smallest cross-section, analysis indicating this to be due to minimal light loss in transport of the TL through the bulk of the silica medium. PMID:26307987

  16. Evaluation of organ doses in adult and paediatric CT examinations based on Monte Carlo simulations and in-phantom dosimetry.

    PubMed

    Fujii, K; Nomura, K; Muramatsu, Y; Takahashi, K; Obara, S; Akahane, K; Satake, M

    2015-07-01

    The aim of this study was to validate the computed tomography dose index (CTDI) and organ doses evaluated by Monte Carlo simulations through comparisons with doses evaluated by in-phantom dosimetry. Organ doses were measured with radio-photoluminescence glass dosemeter (RGD) set at various organ positions within adult and 1-y-old anthropomorphic phantoms. For the dose simulations, the X-ray spectrum and bow-tie filter shape of a CT scanner were estimated and 3D voxelised data of the CTDI and anthropomorphic phantoms from the acquired CT images were derived. Organ dose simulations and measurements were performed with chest and abdomen-pelvis CT examination scan parameters. Relative differences between the simulated and measured doses were within 5 % for the volume CTDI and 13 % for organ doses for organs within the scan range in adult and paediatric CT examinations. The simulation results were considered to be in good agreement with the measured doses. PMID:25848103

  17. [Radon in workplaces, a review].

    PubMed

    Di Loreto, G; Sacco, A; Felicioli, G

    2010-01-01

    Radon is a chemical radioactive element. It occurs naturally as the decay product of radium; it's responsible for the majority of the mean public exposure to ionizing radiation. It is often the single largest contributor to an individual's background radiation dose, and is the most variable from location to location. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as attics, and basements. Breathing in radon is a cause of lung cancer. In Italy, high levels of radon should be found in underground spaces such as wineries, historical buildings, hot springs or mushrooms farms, and it's a hazard all this workplaces. To ensure the health and safety of employees and others who have access to their work environment, the occupational physician can program inexpensive surveys (with dosemeters) and develop an information plan. PMID:21438274

  18. The utilization of bubble detector technology in the development of a Combination Area Neutron Spectrometer (CANS)

    SciTech Connect

    Buckner, M.A.; Sims, C.S.

    1991-01-01

    The compact and relatively inexpensive Combination Area Neutron Spectrometer (CANS) should provide neutron spectral capabilities heretofore available only via complex set-ups and time-consuming, painstaking calculations. Some of its strong points include the measurement of neutron fluence and the need for only a single algorithm, with a single solution, regardless of the spectra. Because fluence, a real quantity, is the foundation of dose equivalent determination, the results of CANS should endure the winds of change accompanying the definition of dose equivalent and its consorted conversion conventions. It is also hoped that personnel applications may be realized in miniature version of CANS, the Personal Neutron Dosemeter/Spectrometer (PENDOSE). 6 refs., 3 figs.

  19. Comparison of radiation dose to operator between transradial and transfemoral coronary angiography with optimised radiation protection: a phantom study.

    PubMed

    Liu, Huiliang; Jin, Zhigeng; Jing, Limin

    2014-03-01

    A growing concern in applying radial access in cardiac catheterisation is the increased operator radiation exposure. This study used an anthropomorphic phantom to simulate transradial and transfemoral coronary angiography with optimised radiation protection conditions. Operator radiation exposure was measured with thermoluminescent dosemeters at prede?ned locations. Compared with the femoral route, the radial route was associated with a dose decrease of 15 % at the operator's chest level with optimised radiation shielding. However, radiation exposure to the operator's hand remained significantly higher when applying radial access even with collective protective equipment used (by a factor of 2). Furthermore, the efficiency of operator radiation protection was found to be dependent on the tube incidence. Awareness should be raised about the significant increase of radiation exposure to operators' hands in transradial coronary angiography. Protection to reduce the dose level to the hands is necessary and should be further improved. PMID:24162374

  20. Design and fabrication of a multipurpose thyroid phantom for medical dosimetry and calibration.

    PubMed

    Mehdizadeh Naderi, Simin; Sina, Sedigheh; Karimipoorfard, Mehrnoosh; Lotfalizadeh, Fatemeh; Entezarmahdi, Mohammad; Moradi, Hamed; Faghihi, Reza

    2016-03-01

    A multipurpose anthropomorphic neck phantom was designed and fabricated for use in medical applications. The designed neck phantom is composed of seven elliptic cylindrical slices with a semi-major axis of 14 cm and a semi-minor axis of 12.5 cm, each having the thickness of 2 cm. The thyroid gland, bony part of the neck, and the windpipe were also built inside the neck phantom. For the purpose of medical dosimetry, some holes were drilled inside the phantom to accommodate the thermoluminescence dosemeters with different shapes and dimensions. For testing the quality of images in nuclear medicine, the thyroid gland was built separately to accommodate the radioactive iodine. Finally, the nuclear medicine images were obtained by inserting (131)I in both male and female thyroid parts. PMID:26124260

  1. Determination of environmental radioactivity (238U, 232Th and 40K) and indoor natural background radiation level in Chennai city (Tamilnadu State), India.

    PubMed

    Babai, K S; Poongothai, S; Punniyakotti, J

    2013-01-01

    An extensive study on the determination of the natural radioactivity ((238)U, (232)Th and (40)K) levels in soil samples of Chennai city, India has been undertaken and the results of the same are compared with the levels reported in other Indian cities as well as other parts of the world. The radioactivity content in the soil samples, the absorbed dose rate, annual effective dose equivalent, radium equivalent activity, internal and external hazard indices were calculated and compared with UNSCEAR 2000 recommended values. In addition to the above, mapping of indoor natural background gamma radiation levels has been made using thermo luminescent dosemeters throughout Chennai city and the same are reported. PMID:22847868

  2. Monte Carlo simulation of the IRSN CANEL/T400 realistic mixed neutron-photon radiation field.

    PubMed

    Lacoste, V; Gressier, V

    2004-01-01

    The calibration of dosemeters and spectrometers in realistic neutron fields simulating those encountered at workplaces is of high necessity to provide true and reliable dosimetric information to the exposed nuclear workers. The CANEL assembly was set-up at IRSN to produce such neutron fields. It comprises a depleted uranium shell, to produce fission neutrons, then iron and water to moderate them and a polyethylene duct. The new presented CANEL facility is used with 3.3 MeV neutrons. Calculations were performed with the MCNP4C code to characterise this mixed neutron-photon expanded radiation field at the position where calibrations are usually performed. The neutron fluence energy and the direction distributions were calculated and the operational quantities were derived from these distributions. The photon fluence and corresponding ambient dose equivalent were also estimated. Comparison with experimental results showed an overall good agreement. PMID:15353634

  3. Thermal neutron calibration channel at LNMRI/IRD.

    PubMed

    Astuto, A; Salgado, A P; Leite, S P; Patrão, K C S; Fonseca, E S; Pereira, W W; Lopes, R T

    2014-10-01

    The Brazilian Metrology Laboratory of Ionizing Radiations (LNMRI) standard thermal neutron flux facility was designed to provide uniform neutron fluence for calibration of small neutron detectors and individual dosemeters. This fluence is obtained by neutron moderation from four (241)Am-Be sources, each with 596 GBq, in a facility built with blocks of graphite/paraffin compound and high-purity carbon graphite. This study was carried out in two steps. In the first step, simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The quality of the resulting neutron fluence in terms of spectrum, cadmium ratio and gamma-neutron ratio was evaluated. In the second step, the system was assembled based on the results obtained on the simulations, and new measurements are being made. These measurements will validate the system, and other intercomparisons will ensure traceability to the International System of Units. PMID:24625545

  4. Comparing Geant4 hadronic models for the WENDI-II rem meter response function.

    PubMed

    Vanaudenhove, T; Dubus, A; Pauly, N

    2013-01-01

    The WENDI-II rem meter is one of the most popular neutron dosemeters used to assess a useful quantity of radiation protection, namely the ambient dose equivalent. This is due to its high sensitivity and its energy response that approximately follows the conversion function between neutron fluence and ambient dose equivalent in the range of thermal to 5 GeV. The simulation of the WENDI-II response function with the Geant4 toolkit is then perfectly suited to compare low- and high-energy hadronic models provided by this Monte Carlo code. The results showed that the thermal treatment of hydrogen in polyethylene for neutron <4 eV has a great influence over the whole detector range. Above 19 MeV, both Bertini Cascade and Binary Cascade models show a good correlation with the results found in the literature, while low-energy parameterised models are not suitable for this application. PMID:22972796

  5. The MATROSHKA facility--dose determination during an EVA.

    PubMed

    Reitz, Guenther; Berger, Thomas

    2006-01-01

    On 29 January 2004 the MATROSHKA facility was launched with a Russian Progress to the International Space Station. MATROSHKA is an ESA project, which has been achieved under the direction of the German Aerospace Center (DLR). The project is a cooperation of >16 research institutes from all over the world and is currently the biggest international experiment in radiation dosimetry ever performed in space. The facility simulates, as exact as possible, an astronaut during an extravehicular activity. It was successfully installed outside the Russian segment 'Zvezda' on 26 February 2004 and will remain there for a 1.5 year exposure period. The main task of the facility is to measure particle fluence and energy spectra, dose and dose rates outside and inside--including organ dose determination--in an anthropomorphic phantom mounted on the outside of the Space Station with passive and active dosemeter systems. PMID:16644992

  6. History of the solar particle event radiation doses on-board aeroplanes using a semi-empirical model and Concorde measurements.

    PubMed

    Lantos, P; Fuller, N

    2003-01-01

    Measurements during solar particle events with dosemeters flying permanently on-board Concorde are used to develop a semi-empirical model, called SiGLE. The model is intended to calculate, for a given flight plan, the dose equivalent received during a solar particle event observed with ground-based neutron monitors. It is successfully in operation in the SIEVERT computerised system intended to improve monitoring of radiation dose received by aircrews, in application to a European Directive. The semi-empirical model is applied to evaluate, for most exposed routes, the radiation doses corresponding to the GLEs observed since 1942 with ion chambers or neutron monitors. The results for the largest GLEs observed in the past are discussed in terms of radiation risk, and guidelines are suggested concerning possible alerts to the aeroplanes in case of events of exceptional magnitude. PMID:14565726

  7. Characterisation of neutron fields at Cernavoda NPP.

    PubMed

    Cauwels, Vanessa; Vanhavere, Filip; Dumitrescu, Dorin; Chirosca, Alecsandru; Hager, Luke; Million, Marc; Bartz, James

    2013-04-01

    Near a nuclear reactor or a fuel container, mixed neutron/gamma fields are very common, necessitating routine neutron dosimetry. Accurate neutron dosimetry is complicated by the fact that the neutron effective dose is strongly dependent on the neutron energy and the direction distribution of the neutron fluence. Neutron field characterisation is indispensable if one wants to obtain a reliable estimate for the neutron dose. A measurement campaign at CANDU nuclear power plant located in Cernavoda, Romania, was set up to characterise the neutron fields in four different locations and to investigate the behaviour of different neutron personal dosemeters. This investigation intends to assist in choosing a suitable neutron dosimetry system at this nuclear power plant. PMID:22874895

  8. Doses to LiF :Ti, Mg chips encapsulated in plastic extremity rings as a result of radon gas exposure.

    PubMed

    Kearfott, Kimberlee J; Noon, Evan P; Rafique, Muhammad

    2015-06-01

    Previous studies measured the effects of (222)Rn on various thermoluminescent dosemeters (TLDs). This study quantified the effects of (222)Rn on LiF : Ti,Mg chips encapsulated in plastic extremity rings. For 28 d, one batch of TLDs was left in a chamber with high radon levels, and another batch in a control chamber with normal background radon levels. A few TLDs in each batch were removed from the rings for direct exposure to the ambient air in each chamber. Passive continuous radon monitors (CRMs) recorded the (222)Rn levels. TLDs were processed using a third-party dosimetry company, CRM data were analysed, and the relationship between integrated (222)Rn concentration and TLD response was determined. The batch of TLDs in the experimental chamber showed a weak response to (222)Rn gas, which was in the order of 0.5 nSv Bq(-1) m(3) d(-1). PMID:25785500

  9. Estimation of annual occupational effective doses from external ionizing radiation at medical institutions in Kenya

    NASA Astrophysics Data System (ADS)

    Korir, Geoffrey; Wambani, Jeska; Korir, Ian

    2011-04-01

    This study details the distribution and trends of doses due to occupational radiation exposure among radiation workers from participating medical institutions in Kenya, where monthly dose measurements were collected for a period of one year ranging from January to December in 2007. A total of 367 medical radiation workers were monitored using thermoluminescent dosemeters. They included radiologists (27%), oncologists (2%), dentists (4%), Physicists (5%), technologists (45%), nurses (4%), film processor technicians (3%), auxiliary staff (4%), and radiology office staff (5%). The average annual effective dose of all categories of staff was found to range from 1.19 to 2.52 mSv. This study formed the initiation stage of wider, comprehensive and more frequent monitoring of occupational radiation exposures and long-term investigations into its accumulation patterns in our country.

  10. Dose evaluation for foetal computed tomography with a 320-row unit in wide-volume mode and an 80-row unit in helical scanning mode: a phantom study.

    PubMed

    Matsunaga, Yuta; Kawaguchi, Ai; Kobayashi, Masanao; Suzuki, Shigetaka; Suzuki, Shoichi; Chida, Koichi

    2016-03-01

    The purpose of this study was to evaluate the maternal and foetal effective doses during foetal computed tomography (CT) and to compare the radiation dose, dose profile and image noise on 80-row CT in helical scanning mode and 320-row CT in wide-volume scanning mode. The radiation doses were measured using thermoluminescent dosemeters implanted at various organ sites of an anthropomorphic pregnant phantom. The foetal doses in the 320-row multi-detector CT (MDCT) and 80-row MDCT units were higher than the volume CT dose index (CTDIvol). The dose profile in the 320-row MDCT overlapped in two places but showed no overlap in the 80-row MDCT. There were no significant differences in image noise between the two scanning modes. The foetal dose evaluation by CTDIvol may underestimate the foetal radiation risk. When using the wide-volume mode, operators must take into account the number of scans and overlap between volumetric sections. PMID:26224738

  11. Neutron spectrometry around a high-energy electron-positron collider using a multi-sphere system with passive detectors.

    PubMed

    Bedogni, R; Esposito, A; Chiti, M; Angelone, M

    2007-01-01

    At the INFN LNF (Frascati), the 510 MeV electron-positron collider DAPhiNE is operating since 1997. The neutron fields in the areas around the accelerator were characterised using a Bonner sphere system. The sensitivity of the system was extended up to 10(2) MeV by means of a lead loaded 12('') sphere. Recently developed thermoluminescence dosemeters (TLDs), with improved neutron sensitivity and gamma rejection properties, were used as central detectors. The new TLD-based spectrometric system was characterised by irradiation in quasi-monoenergetic or radionuclide neutron fields. In addition, numerical verifications with the Monte Carlo code MCNP were performed. This work addresses this new TLD-based spectrometer and presents the spectral measurements performed in a point of test around DAPhiNE. The results are compared with those obtained, in the same point, with a previously validated Bonner sphere system based on an active (6)LiI(Eu) scintillator. PMID:17502313

  12. Dosimetric investigations on Mars-96 mission.

    PubMed

    Semkova, J; Dachev, T s; Matviichuk, Y u; Koleva, R; Tomov, B; Baynov, P; Petrov, V; Nguyen, V; Siegrist, M; Chene, J; d'Uston, C; Cotin, F

    1994-10-01

    The dosimetric experiments Dose-M and Liulin as part of the more complex French-German-Bulgarian-Russian experiments for the investigation of the radiation environment for Mars-96 mission are described. The experiments will be realized with dosemeter-radiometer instruments, measuring absorbed dose in semiconductor detectors and the particle flux. Two detectors will be mounted on board the Mars-96 orbiter. Another detector will be on the guiderope of the Mars-96 Aerostate station. The scientific aims of Dose-M and Liulin experiments are: Analysis of the absorbed dose and the flux on the path and around Mars behind different shielding. Study of the shielding characteristics of the Martian atmosphere from galactic and solar cosmic rays including solar proton events. Together with the French gamma-spectrometer and the German neutron detectors the investigation of the radiation environment on the surface of Mars and in the atmosphere up to 4000 m altitude will be conducted. PMID:11540012

  13. Eye lens dosimetry: task 2 within the ORAMED project.

    PubMed

    Gualdrini, G; Mariotti, F; Wach, S; Bilski, P; Denoziere, M; Daures, J; Bordy, J-M; Ferrari, P; Monteventi, F; Fantuzzi, E

    2011-03-01

    The ORAMED (Optimization of RAdiation protection for MEDical staff) project is funded by EU-EURATOM within the 7 Framework Programme. Task 2 of the project is devoted to study the dose to the eye lens. The study was subdivided into various topics, starting from a critical revision of the operational quantity H(p)(3), with the corresponding proposal of a cylindrical phantom simulating as best as possible the head in which the eyes are located, the production of a complete set of air kerma to dose equivalent conversion coefficients for photons from 10 keV to 10 MeV, and finally, the optimisation of the design of a personal dosemeter well suited to respond in terms of H(p)(3). The paper presents some preliminary results. PMID:21335629

  14. Simulated workplace neutron fields

    NASA Astrophysics Data System (ADS)

    Lacoste, V.; Taylor, G.; Rttger, S.

    2011-12-01

    The use of simulated workplace neutron fields, which aim at replicating radiation fields at practical workplaces, is an alternative solution for the calibration of neutron dosemeters. They offer more appropriate calibration coefficients when the mean fluence-to-dose equivalent conversion coefficients of the simulated and practical fields are comparable. Intensive Monte Carlo modelling work has become quite indispensable for the design and/or the characterization of the produced mixed neutron/photon fields, and the use of Bonner sphere systems and proton recoil spectrometers is also mandatory for a reliable experimental determination of the neutron fluence energy distribution over the whole energy range. The establishment of a calibration capability with a simulated workplace neutron field is not an easy task; to date only few facilities are available as standard calibration fields.

  15. Characterisation of bubble detectors for aircrew and space radiation exposure.

    PubMed

    Green, A R; Bennett, L G I; Lewis, B J; Tume, P; Andrews, H R; Noulty, R A; Ing, H

    2006-01-01

    The Earth's atmosphere acts as a natural radiation shield which protects terrestrial dwellers from the radiation environment encountered in space. In general, the intensity of this radiation field increases with distance from the ground owing to a decrease in the amount of atmospheric shielding. Neutrons form an important component of the radiation field to which the aircrew and spacecrew are exposed. In light of this, the neutron-sensitive bubble detector may be ideal as a portable personal dosemeter at jet altitudes and in space. This paper describes the ground-based characterisation of the bubble detector and the application of the bubble detector for the measurement of aircrew and spacecrew radiation exposure. PMID:16987919

  16. Reduction of occupational radiation dose in staff at the cardiac catheterisation laboratory by protective material placed on the patient.

    PubMed

    Ordiales, J M; Nogales, J M; Snchez-Casanueva, R; Vano, E; Fernndez, J M; lvarez, F J; Ramos, J; Martnez, G; Lpez-Mnguez, J R

    2015-07-01

    Reducing occupational radiation dose in cardiac catheterisation laboratories is one of the objectives of the radiation protection system because the procedures performed involve high levels of radiation compared with others in health care. Recommendations on protection methods used are referred to different structural types and personal protection tools. In this work, the effectiveness of a shielding drape above the patient in different geometric shapes for a standard procedure in interventional cardiology was evaluated. Values of personal dose equivalent Hp(10) obtained simultaneously with three active electronic semiconductor dosemeters located at the usual position of staff and at the C-arm have been used to show the usefulness of the shielding drape. PMID:25848096

  17. Vertical distribution of radiation dose rates in the water of a brackish lake in Aomori Prefecture, Japan.

    PubMed

    Ohtsuka, Yoshihito; Iyogi, Takashi; Ueda, Shinji; Hisamatsu, Shun'ichi

    2015-11-01

    Seasonal radiation dose rates were measured with glass dosemeters housed in watertight cases at various depths in the water of Lake Obuchi, a brackish lake in Aomori Prefecture, Japan, during fiscal years 2011-2013 to assess the background external radiation dose to aquatic biota in the lake. The mean radiation dose in the surface water of the lake was found to be 27 nGy h(-1), which is almost the same as the absorption dose rate due to cosmic ray reported in the literature. Radiation dose rates decreased exponentially with water depth down to a depth of 1 m above the bottom sediment. In the water near the sediment, the dose rate increased with depth owing to the emission of γ-rays from natural radionuclides in the sediment. PMID:25944958

  18. Dose measurements in pulsed radiation fields with commercially available measuring components.

    PubMed

    Friedrich, Sabrina; Hupe, Oliver

    2016-03-01

    Dose measurements in pulsed radiation fields with dosemeters using the counting technique are known to be inappropriate. Therefore, there is a demand for a portable device able to measure the dose in pulsed radiation fields. As a detector, ionisation chambers seem to be a good alternative. In particular, using a secondary standard ionisation chamber in combination with a reliable charge-measuring system would be a good solution. The Physikalisch-Technische Bundesanstalt (PTB) uses secondary standard ionisation chambers in combination with PTB-made measuring electronics for dose measurements at its reference fields. However, for general use, this equipment is too complex. For measurements on-site, a mobile special electronic system [Hupe, O. and Ankerhold, U. Determination of ambient and personal dose equivalent for personnel and cargo security screening. Radiat. Prot. Dosim. 121: (4), 429-437 (2006)] has been used successfully. Still, for general use, there is a need for a much simpler but a just as good solution. A measuring instrument with very good energy dependence for H*(10) is the secondary standard ionisation chamber HS01. An easy-to-use and commercially available electrometer for measuring the generated charges is the UNIDOS by PTW Freiburg. Depending on the expected dose values, the ionisation chamber used can be selected. In addition, measurements have been performed by using commercially available area dosemeters, e.g. the Mini SmartION 2120S by Thermo Scientific, using an ionisation chamber and the Szintomat 6134 A/H by Automess, using a scintillation detector. PMID:26056377

  19. Indoor inhalation dose estimates due to radon and thoron in some areas of South-Western Punjab, India.

    PubMed

    Kumar, Sanjeev; Singh, Surinder; Bajwa, Bikramjit Singh; Singh, Bhupinder; Sabharwal, Arvind D; Eappen, K P

    2012-08-01

    LR-115 (type II)-based radon-thoron discriminating twin-chamber dosemeters have been used for estimating radon ((222)Rn) and thoron ((220)Rn) concentrations in dwellings of south-western Punjab, India. The present study region has shown pronounced cases of cancer incidents in the public [Thakur, Rao, Rajwanshi, Parwana and Kumar (Epidemiological study of high cancer among rural agricultural community of Punjab in Northern India. Int J Environ Res Public Health 2008; 5(5):399-407) and Kumar et al. (Risk assessment for natural uranium in subsurface water of Punjab state, India. Hum Ecol Risk Assess 2011;17:381-93)]. Radon being a carcinogen has been monitored in some dwellings selected randomly in the study area. Results show that the values of radon ((222)Rn) varied from 21 to 79 Bq m(-3), with a geometric mean of 45 Bq m(-3) [geometric standard deviation (GSD 1.39)], and those of thoron ((220)Rn) from minimum detection level to 58 Bq m(-3) with a geometric mean of 19 Bq m(-3) (GSD 1.88). Bare card data are used for computing the progeny concentration by deriving the equilibrium factor (F) using a root finding method [Mayya, Eappen and Nambi (Methodology for mixed field inhalation dosimetry in monazite areas using a twin-cup dosemeter with three track detectors. Radiat Prot Dosim 1998;77(3):177-84)]. Inhalation doses have been calculated and compared using UNSCEAR equilibrium factors and by using the calculated F-values. The results show satisfactory comparison between the values. PMID:22267272

  20. Indoor radon survey in dwellings of nine cities in the Eastern and the Western provinces of Saudi Arabia.

    PubMed

    Abu-Jarad, F; Fazal-ur-Rehman; Al-Jarallah, M I; Al-Shukri, A

    2003-01-01

    The results of a first phase of an indoor radon survey in a total of 1610 dwellings distributed in nine cities of the Eastern and the Western provinces of Saudi Arabia are presented. The objective of this radon survey was to obtain representative indoor radon data for seven cities in the Eastern province. Khafji, Hafr Al-Batin, Abqaiq, Qatif, Al-Ahsa, Dammam and Khobar and to compare this with two cities in the Western province, Madina and Taif. So far, detailed radon data is not available for Saudi Arabia: therefore, this radon survey provides a base line for Saudi Arabia in the Radon World Atlas. On average, 200 indoor radon dosemeters were distributed in each city and placed for a period of one year starting from May 2001 to May 2002. The total number of collected dosemeters was 847. A total of 724 houses and 98 schools were covered in this survey. The results of the survey in the cities showed that the overall minimum, maximum and average radon concentrations were 1, 137 and 22 Bq m(-3), respectively. Geometric mean and geometric standard deviations of the radon distribution were found to be 18 and 1.92, respectively. In one of the dwellings in Qatif city, radon concentration, measured by a passive system and then confirmed by an active system, was found to be 535 +/- 23 and 523 +/- 22 Bq m(-3), respectively. The result of a radon survey in 98 schools showed that the minimum, maximum and average radon concentrations were 1, 70 and 19 Bq m(-3), respectively. The average radon concentration for each city was also determined. The lowest average radon concentration (8 Bq m(-3)) was found in Al-Ahsa while the highest average concentration (40 Bq m(-3)) was found in Khafji. PMID:14690323

  1. Angular dependence of a simple accident dosimeter

    SciTech Connect

    Devine, R. T.; Romero, L. L.; Olsher, R. H.

    2004-01-01

    A simple dosimeter made of a sulfur tablet, bare and cadmium covered indium foils and a cadmium covered copper foil has been modeled using MCNP5. Studies of the model without phantom or other confounding factors have shown that the cross sections and fluence-to-dose factors generated by the Monte Carlo method agree with those generated by analytic expressions for the high energy component. The threshold cross sections for the detectors on a phantom were calculated. The resulting doses assigned agree well with exposures made to three critical assemblies. In this study the angular dependence on a phantom is studied and compared with measurements taken on the GODIVA reactor. The dosimeter positions on the phantom are facing the source, on the back and the side. In previous papers the modeling of a simple dosimeter made of a sulfur tablet, bare and cadmium covered indium foils and a cadmium covered copper foil has been modeled using MCNP5. The conclusion made was that most of the neutron dose from criticality assemblies results from the high energy neutron fluences determined by the sulfur and indium detectors. The results using doses measured from the GODIVA, SHEBA, and bare and lead shielded SILENE reactors confirmed this. The angular dependence of an accident dosemeter is of interest in evaluating the exposure of personnel. To investigate this effect accident dosemeters were placed on a phantom and exposed to the GODIVA reactor at phantom orientations of 0{sup o}, 45{sup o}, 90{sup o}, 135{sup o}, and 180{sup o} to the assembly center line.

  2. Radiation dose evaluation in 64-slice CT examinations with adult and paediatric anthropomorphic phantoms

    PubMed Central

    Fujii, K; Aoyama, T; Yamauchi-Kawaura, C; Koyama, S; Yamauchi, M; Ko, S; Akahane, K; Nishizawa, K

    2009-01-01

    The objective of this study was to evaluate the organ dose and effective dose to patients undergoing routine adult and paediatric CT examinations with 64-slice CT scanners and to compare the doses with those from 4-, 8- and 16-multislice CT scanners. Patient doses were measured with small (<7 mm wide) silicon photodiode dosemeters (34 in total), which were implanted at various tissue and organ positions within adult and 6-year-old child anthropomorphic phantoms. Output signals from photodiode dosemeters were read on a personal computer, from which organ and effective doses were computed. For the adult phantom, organ doses (for organs within the scan range) and effective doses were 835 mGy and 718 mSv, respectively, for chest CT, and 1233 mGy and 1021 mSv, respectively, for abdominopelvic CT. For the paediatric phantom, organ and effective doses were 417 mGy and 37 mSv, respectively, for chest CT, and 514 mGy and 39 mSv, respectively, for abdominopelvic CT. Doses to organs at the boundaries of the scan length were higher for 64-slice CT scanners using large beam widths and/or a large pitch because of the larger extent of over-ranging. The CT dose index (CTDIvol), doselength product (DLP) and the effective dose values using 64-slice CT for the adult and paediatric phantoms were the same as those obtained using 4-, 8- and 16-slice CT. Conversion factors of DLP to the effective dose by International Commission on Radiological Protection 103 were 0.024 mSv?mGy?1?cm?1 and 0.019 mSv?mGy?1?cm?1 for adult chest and abdominopelvic CT scans, respectively. PMID:19934069

  3. Visible photoluminescence of color centers in LiF crystals for absorbed dose evaluation in clinical dosimetry

    NASA Astrophysics Data System (ADS)

    Villarreal-Barajas, J. E.; Piccinini, M.; Vincenti, M. A.; Bonfigli, F.; Khan, R. F.; Montereali, R. M.

    2015-04-01

    Among insulating materials, lithium fluoride (LiF) has been successfully used as ionizing radiation dosemeter for more than 60 years. Thermoluminescence (TL) has been the most commonly used reading technique to evaluate the absorbed dose. Lately, optically stimulated luminescence (OSL) of visible emitting color centers (CCs) has also been explored in pure and doped LiF. This work focuses on the experimental behaviour of nominally pure LiF crystals dosemeters for 6 MV x rays at low doses based on photoluminescence (PL) of radiation induced CCs. Polished LiF crystals were irradiated using 6 MV x rays produced by a clinical linear accelerator. The doses (absorbed dose to water) covered the 1-100 Gy range. Optical absorption spectra show stable formation of primary F defects up to a maximum concentration of 2×1016 cm-3, while no significant M absorption band at around 450 nm was detected. On the other hand, under Argon laser excitation at 458 nm, PL spectra of the irradiated LiF crystals clearly exhibited the characteristic F2 and F+3 visible broad emission bands. Their sum intensity is linearly proportional to the absorbed dose in the investigated range. PL integrated intensity was also measured using a conventional fluorescence optical microscope under blue lamp illumination. The relationship between the absorbed dose and the integrated F2 and F+3 PL intensities, represented by the net average pixel number in the optical fluorescence images, is also fairly linear. Even at the low point defect densities obtained at the investigated doses, these preliminary experimental results are encouraging for further investigation of CCs PL in LiF crystals for clinical dosimetry.

  4. Mixed field peronnel dosimetry: Part 1, High temperature peak characteristics of the reader-annealed TLD-600

    SciTech Connect

    Liu, J.C. ); Sims, C.S. )

    1991-02-01

    The high temperature peaks (TL peaks 6--7) of TLD-600 are known to have higher responses to high LET radiation than to low LET radiation. These high temperature peak characteristics were studied for the automatic reader-annealed Harshaw albedo neutron TLD. The high temperature peaks response is linear for neutrons over the dose equivalent range tested (0.05--3 mSv of a {sup 252}Cf source moderated by a 15 cm radius polyethylene sphere), but is supralinear above 20 mSv of {sup 137}Cs photons. The peaks ratio (peaks 6--7/peaks 3--5) of TLD-600 is 0.15 for neutrons of any incident energy, 0.01 for {sup 137}Cs gammas, and 0.02 for M-150 x-rays. Based on the high temperature peak characteristics, a mixed field neutron-photon personnel dosimetry methodology using a single TLD-600 element was developed. The dosimetric method was evaluated in mixed {sup 238}PuBe + {sup 137}Cs fields with four neutron-gamma dose equivalent ratios, and the neutron, photon and total dose equivalent estimations are better than 20% except in one case. However, it was found that the neutron and photon dose equivalent estimations are sensitive to the neutron and photon peaks ratios, depending on the neutron-photon dose equivalent ratio and the neutron source in the mixed field. Therefore, a successful use of this method requires knowledge of the photon and neutron energies in the mixed field. 13 refs., 6 figs., 2 tabs.

  5. Catalytic methods for improved coal liquefaction and hydrotreating: Quarterly report No. 5 for the period September 23, 1986 through December 22, 1986

    SciTech Connect

    Hirschon, A.S.; Laine, R.M.; Wilson, R.B. Jr.

    1987-01-01

    The goal of this project is to optimize the reaction conditions for coal liquefaction and upgrading coal liquids. Accomplishments for this quarter are presented for the following tasks: (1) synthesis of catalysts; (2) hydrodenitrogenation (HDN) activity of catalysts with model system; and (3) catalytic reactions and additives on coal and coal liquids. For task 1, variations of bi/sup -/, tri/sup -/, and tetrametallic catalysts (RuMo, FeCoMo, RuCoMo, RuFeCoMo), were prepared to compare with catalysts prepared during the last quarter. For task 2, we found that the ruthenium-doped organometallic catalyst, RuMo (OM), was considerably more active and more selective than the RuNiMo (OM) catalyst. The RuFeCoMo catalysts, formed from doping ruthenium on FeCoMo, was also a very active catalyst, and far more active than the corresponding FeRuCoMo catalyst, formed from doping iron on RuCoMo. We treated an SRC-II coal liquid with the RuCoMo catalyst, recovered it, and tested it for HDN activity on our model systems. This aged catalyst was highly selective toward aromatic products and although it had reduced HDN activity compared to a fresh sample, it was still more active than the nonpromoted CoMo catalyst. For task 3, an SRC-II coal liquid was treated with a promoted Harshaw CoMo catalyst, RuCoMo. Although the activity of this catalyst was similar to that of the CoMo catalyst, the hydrogen consumption was less with ruthenium catalyst. 7 refs., 3 tabs.

  6. An investigation of gamma background radiation in Hamadan province, Iran.

    PubMed

    Rostampour, Nima; Almasi, Tinoosh; Rostampour, Masoumeh; Mohammadi, Mohammad; Ghazikhanlou Sani, Karim; Khosravi, Hamid R; Pooya, S Mehdi Hosseini; Golzar, Bahman; Jabari Vesal, Naghi

    2012-12-01

    The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO(4):Dy thermoluminecense dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate  outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22  and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in  Hamadan province. PMID:22570508

  7. Surface-modified polyblend membranes for gas separation process

    SciTech Connect

    Yang, T.

    1989-01-01

    Blends of polymethyl-methacrylate (PMMA) and poly (vinylidene fluoride) (PVDF) were studied. It was found that concentration of PVDF less than 40 wt% lead to miscible systems when the membranes are cast from dimethyl sulfoxide solvent. The miscible polyblends were used as media for the separation of a 50:50 carbon dioxide:methane gas mixture. The measurements of transport properties were made using a Harshaw permeability cell with FTIR detection. Both the transient and steady state permeabilities of carbon dioxide and methane were determined. Low pressures of the gas mixture were used to minimize any artifacts arising from plasticization effects due to carbon dioxide sorption. The results showed that the separation factor, the ratio of the measured permeabilities of carbon dioxide and methane, was decreased by increasing the content of PVDF. Thermodynamic concepts were applied to predict the permeabilities of carbon dioxide and methane in pure amorphous PVDF and the polyblends. Surface characterization of the polymer blends, prior to surface modification, was done using contact angle, ESCA and ISS measurements. Acid hydrolysis of the surface region to form poly (methacrylic acid) (PMAA) was carried out using dilute (65 vol%) sulfuric acid. Different reagents for post-treatment of the hydrolyzed membranes led to different surface structures and morphologies, that dominated the final separation and permeabilities of both gases. Water swelled the surface layer, and caused defects after it was removed, that deteriorated the separation efficiency of the membranes. Isopropyl alcohol post-treatment led to a denser surface layer and increased the separation efficiency. FTIR-ATR, density measurements, and optical and electron microscopies were utilized to help interpret the transport property data.

  8. Theoretical and practical implications of the effects of temperature during irradiation and during pre- and post-irradiation storage on the response of thermoluminescence dosimeters

    SciTech Connect

    Gail de Planque, E.

    1984-01-01

    Experiments have been conducted to determine the applicability of the Randall-Wilkins theory for describing the behavior of CaF/sub 2/:Mn thermoluminescence dosimeters (Harshaw TLD-400 chips). Results were obtained for four different conditions: irradiation followed by storage, irradiation after storage, irradiation both preceded and followed by storage, and continuous simultaneous irradiation and storage. The experiments were performed for storage intervals of approximately 1, 2, 3, 5, 6 and 7 days at five different storage temperatures: -25, +20, +65, +150 and +175/sup 0/C. The results indicate fading that is described not by the Randall-Wilkins theory but rather as a linear function of the logarithm of the storage time. While the results suggest that the trapping efficiency is independent of temperature, they do demonstrate a small decrease in TL response with storage time prior to irradiation which is independent of temperature and time (>17 hours) and hence probably not dosimetric in origin but perhaps optically related. Glow curve analyses support the concept of a band of traps rather than a single trap. The overall results are compared to other data available in the literature most of which is for room-temperature storage. These data, for storage periods ranging from minutes to one year, can also be described as a linear function of the logarithm of the storage time and are remarkably consistent when uniformly normalized. Although peripheral experiments revealed problems associated with self-irradiation as well as a decline in sensitivity with use, the stability experiment results verify the highly favorable stability properties of CaF/sub 2/:Mn for widespread application.

  9. Catalytic hydrogenation of coal-derived liquids. Interim report, December 1981-February 1982

    SciTech Connect

    Berg, L.; McCandless, F.P.

    1982-03-01

    The optimum relationship between temperature and space velocity for the 4% CoO, 8% MoO/sub 3/, 1% NiO, 8% WO/sub 3/ MSU catalyst for upgrading SRC-II proved to be 425/sup 0/C and 0.5 SV, best yield; 475/sup 0/C and 0.75 SV, highest naphtha yield; and 500/sup 0/C and 1.25 SV, greatest denitrogenation. The octane number of the 40 to 205/sup 0/C gasoline from the 500/sup 0/C and 1.25 SV run is 90.3. Increasing the operating pressure from the usual 1100 psi to 2000 psi at 425/sup 0/C and 1.25 SV had a beneficial effect on denitrogenation and liquid yield but virtually no effect on desulfurization. The investigation of partially hydrogenated Koppers creosote oil as a hydrogen donor agent was begun with one hydrogenation of the creosote having been completed. The effect of adding 1.5% water to the feed SRC-II to attain specification grade denitrogenation with Harshaw HT-400 catalyst was reported by us previously. When this procedure is applied to the MSU 4% CoO, 8% MoO/sub 3/, 8% WO/sub 3/ catalyst, it again improves the denitrogenation. A study of desulfurization of SRC-II with five different base materials having median pore diameters ranging from 90A to 220A indicated that the highest activity occurs in the 115 to 161A range, and that activity decreases as median pore diameter goes below 90A or above 160A.

  10. Orthodontic radiographic procedures--how safe are they?

    PubMed

    Buch, B; Fensham, R

    2003-02-01

    Parents of children subjected to radiographic procedures for orthodontic purposes occasionally express concern about possible radiation overdose to sensitive structures in the head and neck region. The following study was designed to determine this. Twenty Harshaw lithium fluoride thermoluminescent dosimeters (TLDs) were irradiated using a calibrated RT 100 X-ray source. These were read in a Toledo 654 TLD reader. The readings of all dosimeters fell within 10% on either side of the mean reading for the dosimeters. Twelve were finally selected which fell closest to the mean. Six of the TLDs were randomly selected and placed in a Rando female phantom in a position corresponding to the lens of the eye-3 in the left and 3 in the right eye. A standard pantomogram was taken of the phantom using an Orthophos machine. The TLDs were then replaced by another two groups of 3 in the same positions in the phantom and a lateral cephalogram taken on the same machine. The TLDs were read in the Toledo reader. Six of the 12 TLDs were then randomly selected for re-use. Three were placed in the phantom in the region of the thyroid and a pantomogram again taken. The procedure was repeated for a cephalogram and the TLDs again read. In all cases the readings of each group of 3 TLDs did not vary by more than 10% on either side of the mean readings. The TLD readings were then converted by means of a conversion factor to actual dose measurements. The doses to left and right eyes and to the thyroid were respectively found to be 0,0151, 0,0222 & 0,0896 mSv for the pantomogram and 0,0351, 0,0183 & 0,0177 mSv for the cephalogram--an almost insignificant dose in terms of the "background equivalent" concept. PMID:12705098

  11. Detection of Thermoluminescence in Post-Gamma Shelf-Aged Polyethylene

    NASA Astrophysics Data System (ADS)

    Gray, Jonathan; Shah Jahan, M.

    2004-11-01

    Polyethylene (PE) of molecular weight 3-6 million mol/gm, commonly known as ultra-high molecular weight PE (UHMWPE) and used in orthopedic joint replacements, was irradiated with gamma rays at sterilization dose ( ˜ 3 MRad of ^60Co) at room temperature (RT) in air and subsequently aged for 5-15 years in the same environment. When heated from RT to 280^oC at 1^oC/s using a commercial thermoluminescence (TL) detector (Harshaw 3500), the aged UHMWPE samples were found to produce luminescence with (glow) peaks near 112^oC, 208^oC and 255^oC. While the 112^oC TL glow peak is attributed to the long-lived oxygen-induced free radicals, the 208^oC and 255^oC glow peaks are assigned to molecular breakdown processes caused by melting of the long-chain molecules. To confirm the correlation between TL and the free radicals, measurements were made on the same samples before and after recording TL using an X-band (9.5 GHz microwave frequency and 100 kHz modulation and detection frequency) electron spin resonance (ESR) spectrometer (Varian E-4). Before TL, ESR produced a broad resonance line centered at g-value 2.013 and peak-to-peak separation of 5.26 G. After TL, a very weak broad ESR signal was detected which may be produced by molecular breakdown or free radicals still present in the sample.

  12. New and improved dispersion and recovery techniques for slurry phase catalysis. Quarterly report, October 1-December 31, 1985. [9-phenanthrol

    SciTech Connect

    Tarrer, A.R.; Curtis, C.W.; Guin, J.A.; Tatarchuk, B.J.

    1985-01-01

    Values of the equilibrium adsorptivity (K/sub i/) and surface reaction rate (k'/sub i/) for several model coal liquid compounds undergoing catalytic hydrogenation using Harshaw 0402T catalyst at 300/sup 0/C were obtained. The model compounds used were naphthalene, acenaphthene, phenanthrene, 1-acenaphthol, 9-phenanthrol, and quinoline. The values obtained at the conditions used imply that the hydrodenitrogenation (HDN) reaction of quinoline is an order of magnitude slower than both the hydrogenation (HYD) of naphthalene, phenanthrene, and acenaphtene, and hydrodeoxygenation (HDO) of 1-acenaphthol and 9-phenanthrol. Values for the equilibrium adsorptivities obtained indicate that the adsorptivity of quinoline is an order of magnitude greater than that of the others. The combination of these facts helps explain why quinoline retards the hydrogenation of naphthalene to a much greater extent than any of the other compounds. The methodology used to determine these values was: The probable hydrogenation, hydrodeoxygenation, or hydrodenitrogenation reaction pathway was identified from the literature or the experiment. Kinetic data, in the form of concentration vs. time, for the various reactions were taken using batch micro-reactors. Using a continuous hydrotreater a value for the steady state conversion of naphthalene was obtained. Using this value and data on the batch HYD of naphthalene values of k'/sub i/ and K/sub i/ for naphthalene were calculated. Using the continuous hydrotreater a new value for the steady state conversion of naphthalene was obtained using feed containing small quantities of a given model inhibitor. From these data, along with kinetic data for each model compound, values of the equilibrium adsorptivity and surface reaction rate for all other compounds were determined. 25 refs., 17 figs., 12 tabs.

  13. The use of LiF (TLD-100) as an out-of-field dosimeter.

    PubMed

    Kry, Stephen F; Price, Michael; Followill, David; Mourtada, Firas; Salehpour, Mohammad

    2007-01-01

    The commonly used thermoluminescent dosimeter TLD-100 (Harshaw Chemical Company, Solon, OH) responds not only to photons and electrons, but also to neutrons that are produced during high-energy therapies. As a result, TLD-100 measurements outside of the treatment field are suspect when high-energy radiation is used. Although alternatives such as TLD-700 do not respond to neutrons, specialty dosimeters of this kind are expensive and are not routinely used in most clinics. In the current study, we examined the accuracy of TLD-100 in measuring the out-of-field photon dose as a function of treatment energy. To determine the accuracy of TLD-100 as compared with TLD-700, TLD-100 was irradiated outside of the treatment field by medical accelerators operated at 6, 10, 15, and 18 MV. In an effort to eliminate the response of TLD-100 to neutrons, TLD capsules were encased in varying thicknesses of cadmium foil (0.25 - 0.75 mm) before being irradiated at 18 MV. The out-of-field TLD-100 was found to be accurate at 6 MV and 10 MV, but to be substantially over-responsive at 15 MV and 18 MV (by up to 1063% relative to TLD-700). By wrapping the TLD-100 in up to 0.75 mm of cadmium, it was possible to drastically reduce (down to 39% on average) the over-response of the TLD-100; however, total removal of the over-responsiveness was not possible. Although TLD-100 is well suited for measuring out-of-field dose at energies as high as 10 MV, at higher energies (15 MV or greater), this dosimeter over-responds substantially and should not be used. Although encasing the TLD in cadmium minimized over-response to a degree, the reduction was not sufficient to make TLD-100 viable for measuring out-of-field dose at high treatment energies. PMID:18449155

  14. Practical experiences with the synthesis of [11C]CH3I through gas phase iodination reaction using a TRACERlabFXC synthesis module.

    PubMed

    Kniess, Torsten; Rode, Katrin; Wuest, Frank

    2008-04-01

    The results of [(11)C]CH(3)I synthesis through hydrogen gas reduction of [(11)C]CO(2) on different nickel catalysts (HARSHAW-nickel, SHIMALITE-nickel, nickel on silica/alumina, nickel nanosize 99.99%) followed by gas phase iodination using a TRACERlab FX(C) synthesis unit are reported. Further reaction parameters such as furnace temperatures, flow rate of hydrogen gas and reduction time were optimized. It was found that reduction of [(11)C]CO(2) proceeded in 28-83% yield depending on the nickel catalyst and temperature. The gas phase iodination (methane conversion) gave 31-62% of [(11)C]CH(3)I depending on temperature and amount of iodine in the iodine furnace. [(11)C]CH(3)I was used for heteroatom methylation reactions exemplified by a piperazine and a phenol (1 and 3). The specific activity of the (11)C-labelled products 2 and 4 was determined after HPLC purification and solid-phase extraction. Compounds 2 and 4 were obtained in 8-14% radiochemical yield (decay-corrected, based upon trapped [(11)C]CH(4)) within 30 min. The specific activity was determined to be in the range of 20-30 GBq/mumol at the end-of-synthesis. Nickel catalyst nanosize was found to be superior compared with other Ni catalysts tested. The relatively low specific activity may be mainly due to carbon contaminations originating from the long copper tubing (500 m) between the cyclotron and the radiochemistry facility. PMID:17683943

  15. Neutron radiation induced degradation of diode characteristics

    NASA Astrophysics Data System (ADS)

    Khanna, S. M.; Pepper, G. T.; Stone, R. E.

    1992-12-01

    Neutron radiation effects on diode current-voltage characteristics have been studied for a variety of diode over 1(10)(exp 13) - 3(10)(exp 15) n/sq cm 1 MeV equivalent neutron fluence range. A classification scheme consisting of three types of neutron effects on diode forward characteristics is proposed here for the first time. For constant forward current I(sub F) higher than that in the generation-recombination regime, the diode voltage V(sub F) either increases with fluence phi (Type 1 diode), on V(sub F) first decreases with phi at lower fluence levels and then increases with phi at higher fluence levels (Type 2 diode), or V(sub F) decreases with phi at all fluence levels used in this work (Type 3 diode). Most of the previous results on p-n junction diodes correspond to Type 1 diode results. Type 2 diode results are rather rare in the literature. Several examples of Type 2 diode results are presented here. Type 3 diode results are reported here for other types of diodes not reported earlier. These results are explained qualitatively in terms of the theories for a p-n junction and for radiation effects on semiconductors. It is shown here that a type 3 diode could be developed as a high neutron fluence monitor with three orders of magnitude higher upper limit than the Harshaw p-i-n diode neutron fluence monitor under evaluation at the US Army Aberdeen Proving Grounds, Aberdeen, Md. The results also suggest a methodology for radiation hard diode development.

  16. The development, characterization, and performance evaluation of a new combination type personnel neutron dosimeter

    SciTech Connect

    Liu, Chweijeng.

    1989-01-01

    A new combination type personnel neutron dosimeter has been designed and developed at the Oak Ridge National Laboratory. The combination personnel neutron dosimeter (CPND) consists of a Harshaw albedo neutron thermoluminescent dosimeter and two bubble detectors. The CPND was developed with the aim of having crude neutron spectrometric capability, universal applicability, better angular response, and an improved lower limit of detection (LLD). The CPND has been well characterized in the following areas: reusability, linearity, LLD, detection capability in mixed neutron-gamma fields, angular dependence, and neutron energy dependence. The characterization was accomplished with irradiations using a {sup 238}Pu-Be source, a {sup 252}Cf(D{sub 2}O) source, a {sup 252}Cf source, a {sup 252}Cf(PE) source, monoenergetic neutrons from accelerator and reactor filtered beams, {sup 137}Cs, and X-rays. Optimum signal readout procedures, signal processing techniques, routine operational usage, and neutron dose equivalent evaluation algorithms for the CPND were developed. Various reference spectra were developed to evaluate the performance (mainly the spectrometric and the dose equivalent measurement capabilities) of the CPND. The performance of the CPND was evaluated by in-situ tests in radiation fields existing in the working environment at ORNL. The spectra in these areas were measured previously with a calibrated Bonner multisphere spectrometer. The CPND also was tested with laboratory radioisotopic sources in single-source and multi-source exposure situations. Finally, the CPND was tested by participating in the fourteenth Personnel Dosimetry Intercomparison Study. The results of the tests mentioned above demonstrated that the CPND meets the ambitious design purposes.

  17. Optical modeling of black chrome solar-selective coatings

    SciTech Connect

    Sweet, J.N.; Pettit, R.B.

    1982-07-01

    Various investigations of coating microstructure are reviewed and the results of these studies are used to develop a picture of the microstructure of black chrome films plated from the Harshaw Chromonyx bath. In this model, the black chrome film is composed of roughly spherical particles which may tend to cluster together. These particles in turn are composed of small crystallites of metallic chrome and various oxides of chrome. The film void volume fraction appears to be greater than or equal to 0.6. The microstructural picture has been idealized to facilitate calculations of the spectral reflectance for films deposited onto nickel substrates and for freestanding or stripped films. In the idealized model, the metallic chromium is assumed to be in the form of spherical crystallites with concentric shells of Cr/sub 2/O/sub 3/ and the crystallite volume fraction is assumed to increase with depth into the film. Various experimental data are utilized to define film thickness, average volume fraction of Cr + Cr/sub 2/O/sub 3/, and volume ratio of Cr to Cr + Cr/sub 2/O/sub 3/. Both the Maxwell-Garnett (MG) and the Bruggeman effective medium theories for the dielectric constant of a composite media are reviewed. The extension of the MG theory to high inclusion volume fractions is discussed. Various forms of the MG theory and the Bruggeman theory are then utilized in reflectance calculations for both regular and stripped films.The results indicate that the MG formalism provides the best overall description of the optical response of black chrome films. Both model and experiment show that the solar absorptance initially decreases slowly as the amount of Cr/sub 2/O/sub 3/ increases; however a rapid decrease occurs when the Cr/sub 2/O/sub 3/ content passes 70 vol %.

  18. SU-E-T-308: Systematic Characterization of the Energy Response of Different LiF TLD Crystals for Dosimetry Applications

    SciTech Connect

    Pena, E; Caprile, P; Sanchez-Nieto, B

    2014-06-01

    Purpose: The thermoluminiscense dosimeters (TLDs) are widely used in personal and clinical dosimetry due to its small size, good sensitivity and tissue equivalence, among other advantages. This study presents the characterization of Lithium Fluoride based TLDs, in terms of their absorbed dose response to successive irradiation cycles in a broad range of beam energies, measured under reference conditions. Methods: Four types of Harshaw TLD chips were used: TLD-100, TLD-600 TLD-700 and 100-H. They were irradiated with 10 photon beams of different energy spectrums, from 28 kVp to 18MV (in 30 consecutive cycles for 6 and 18 MV). Results: It was found that the response of the dosimetric system was stabilized (less than ±3%) after 10 cycles for TLD-600 and TLD-700. In the case of TLD-100 and TLD-100H this dependence was not observed. A decreased response to increasing beam energy in terms of absorbed dose to water was observed, as expected, except for TLD-100H which showed the opposite behavior. The less energy dependent detector was the TLD-100H exhibiting a maximum deviation of 12%. The highest variation observed was 33% for TLD-100. The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy. Conclusion: The study allowed the determination of calibration factors in absorbed dose for a wide range of energies and materials for different dosimetric applications, such as in-vivo dosimetry during imaging and radiotherapy.

  19. SU-E-J-69: Evaluation of the Lens Dose On the Cone Beam IGRT Procedures

    SciTech Connect

    Palomo-Llinares, R; Gimeno-Olmos, J; Carmona Meseguer, V; Lliso-Valverde, F; Candela-Juan, C; Perez-Calatayud, J; Pujades, M; Ballester, F

    2014-06-01

    Purpose: With the establishment of the IGRT as a standard technique, the extra dose that is given to the patients should be taken into account. Furthermore, it has been a recent decrease of the dose threshold in the lens, reduced to 0.5 Gy (ICRP ref 4825-3093-1464 on 21st April, 2011).The purpose of this work was to evaluate the extra dose that the lens is receive due to the Cone-Beam (CBCT) location systems in Head-and-Neck treatments. Methods: The On-Board Imaging (OBI) v 1.5 of the two Varian accelerators, one Clinac iX and one True Beam, were used to obtain the dose that this OBI version give to the lens in the Head-and-Neck location treatments. All CBCT scans were acquired with the Standard Dose Head protocol (100 kVp, 80 mA, 8 ms and 200 degree of rotation).The measurements were taken with thermoluminescence (TLD) EXTRAD (Harshaw) dosimeters placed in an anthropomorphic phantom over the eye and under 3 mm of bolus material to mimic the lens position. The center of the head was placed at the isocenter. To reduce TLD energy dependence, they were calibrated at the used beam quality. Results: The average lens dose at the lens in the OBI v 1.5 systems of the Clinac iX and the True Beam is 0.071 and 0.076 cGy/CBCT, respectively. Conclusions: The extra absorbed doses that receive the eye lenses due to one CBCT acquisition with the studied protocol is far below the new ICRP recommended threshold for the lens. However, the addition effect of several CBCT acquisition during the whole treatment should be taken into account.

  20. Improving neutron dosimetry using bubble detector technology

    SciTech Connect

    Buckner, M.A.

    1993-02-01

    Providing accurate neutron dosimetry for a variety of neutron energy spectra is a formidable task for any dosimetry system. Unless something is known about the neutron spectrum prior to processing the dosimeter, the calculated dose may vary greatly from that actually encountered; that is until now. The entrance of bubble detector technology into the field of neutron dosimetry has eliminated the necessity of having an a priori knowledge of the neutron energy spectra. Recently, a new approach in measuring personnel neutron dose equivalent was developed at Oak Ridge National Laboratory. By using bubble detectors in combination with current thermoluminescent dosimeters (TLDs) as a Combination Personnel Neutron Dosimeter (CPND), not only is it possible to provide accurate dose equivalent results, but a simple four-interval neutron energy spectrum is obtained as well. The components of the CPND are a Harshaw albedo TLD and two bubble detectors with theoretical energy thresholds of 100 key and 1500 keV. Presented are (1) a synoptic history surrounding emergence of bubble detector technology, (2) a brief overview of the current theory on mechanisms of interaction, (3) the data and analysis process involved in refining the response functions, (4) performance evaluation of the original CPND and a reevaluation of the same data under the modified method, (5) the procedure used to determine the reference values of component fluence and dose equivalent for field assessment, (6) analysis of the after-modification results, (7) a critique of some currently held assumptions, offering some alternative explanations, and (8) thoughts concerning potential applications and directions for future research.

  1. Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV

    SciTech Connect

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

    2010-09-27

    The personal dose equivalent, H{sub p}(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity Effective Dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk where personal dosemeters are usually worn and in this instance a suitable approximation is a 30 cm X 30 cm X 15 cm slab-type phantom. For this condition the personal dose equivalent is denoted as H{sub p,slab}(d) and the depths, d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several MeV, however, data to higher energies are limited. In this work conversion coefficients up to 1 GeV have been calculated for H{sub p,slab}(10) and H{sub p,slab}(3) using both the kerma approximation and by tracking secondary charged particles. For H{sub p}(0.07) the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H{sub p,slab}(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared to the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance.

  2. Measurements of environmental background radiation at location of coal-fired power plants.

    PubMed

    Adrovic, F; Proki?, M; Ninkovi?, M M; Glisi?, R

    2004-01-01

    Environmental radiation monitoring in the vicinity of coal-fired power plants which are used primarily to determine the variability in measured background exposures are presented in this article; this is in order to estimate the contribution due to the plants' operation. Measurements have been done using a multi-element, high sensitive dosemeter system composed of three solid, properly filtered, sintered CaSO4:Dy thermoluminescent detectors, and one low-atomic number, MgB4O7:Dy,Na thermoluminiscencent detector produced at the Vinca Institute. The dosemeters were deployed quarterly 1 m above ground level at locations within 20 km of the power plants. Twenty urban and suburban measured stations were established. Measurements were carried out over one year period, from the beginning of the summer of 1995 to the end of the spring of 1996. The registered annual absorbed dose in air, from all of the 20 stations, vary from 0.91 to 1.46 mGy a(-1). One of the highest values of the annual absorbed dose was measured at the station near to the plant, i.e. at the place the most exposed to the lighter fly ash from the plant stack, as it was expected. The annual absorbed dose registered at the measuring stations that were selected as a control because they were situated practically away from possible influence of the plants were from 0.91 to 0.98 mGy a(-1). The above values of absorbed doses become very important, by concurrence of the circumstances, because they represent the zero background radiation level before the incidence of depleted uranium over former Yougoslav territory in the Kosovo region in the spring of 1999. These measured absorbed dose exposures have to be compared with corresponding absorbed dose rates from the natural sources, such as soil having an exposure of 18-93 nGy h(-1) (average 35 nGy h(-1)) according to the UNSCEAR 2000 Report. This investigation has been primarily done in order to check the impact of coal-fired power plants on the background radiation level in its vicinity. According to the experimental results, influence was confirmed both qualitatively and quantitatively. PMID:15385680

  3. WE-D-17A-05: Measurement of Stray Radiation Within An Active Scanning Proton Therapy Facility: EURADOS WG9 Intercomparison Exercise of Active Dosimetry Systems

    SciTech Connect

    Farah, J; Trompier, F; Stolarczyk, L; Klodowska, M; Liszka, M; Olko, P; Algranati, C; Fellin, F; Schwarz, M; Domingo, C; Romero-Exposito, M; Dufek, V; Frojdh, E; George, S; Harrison, R; Kubancak, J; Ploc, O; Knezevic, Z; Majer, M; Miljanic, S; and others

    2014-06-15

    Purpose: Intercomparison of active dosemeters in the measurement of stray radiation at the Trento active-scanning proton therapy facility. Methods: EURADOS WG9 carried out a large intercomparison exercise to test different dosemeters while measuring secondary neutrons within a 230 MeV scanned proton therapy facility. Detectors included two Bonner Sphere Spectrometers (BSS), three tissue equivalent proportional counters (TEPCHawk) and six rem-counters (Wendi II, Berthold, RadEye, a regular and an extended-range Anderson and Braun NM2B counters). Measurements of neutron ambient dose equivalents, H*(10), were done at several positions inside (8 positions) and outside (3 positions) the treatment room while irradiating a water tank phantom with a 10 × 10 × 10 cc field. Results: A generally good agreement on H*(10) values was observed for the tested detectors. At distance of 2.25 m and angles 45°, 90° and 180° with respect to the beam axis, BSS and proportional counters agreed within 30%. Higher differences (up to 60%) were observed at the closest and farthest distances, i.e. at positions where detectors sensitivity, energy, fluence and angular response are highly dependent on neutron spectra (flux and energy). The highest neutron H*(10) value, ∼60 microSv/Gy, was measured at 1.15 m along the beam axis. H*(10) decreased significantly with the distance from the isocenter dropping to 1.1 microSv/Gy at 4.25 m and 90° from beam axis, ∼2 nanoSv/Gy at the entrance of the maze, 0.2 nanoSv/Gy at the door outside the room and below detection limit in the gantry control room and at an adjacent room. These values remain considerately lower than those of passively scattered proton beams. BSS and Hawk unfolded spectra provide valuable inputs when studying the response of each detector. Conclusion: TEPCs and BSS enable accurate measurements of stray neutrons while other rem-meters also give satisfactory results but require further improvements to reduce uncertainties.

  4. Personal dose equivalent conversion coefficients for photons to 1 GeV.

    PubMed

    Veinot, K G; Hertel, N E

    2011-04-01

    The personal dose equivalent, H(p)(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity effective dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk, where personal dosemeters are usually worn, and in this instance a suitable approximation is a 30 30 15 cm(3) slab-type phantom. For this condition, the personal dose equivalent is denoted as H(p,slab)(d) and the depths, d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several megaelectronvolts, however, data to higher energies are limited. In this work, conversion coefficients up to 1 GeV have been calculated for H(p,slab)(10) and H(p,slab)(3) both by using the kerma approximation and tracking secondary charged particles. For H(p)(0.07), the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H(p,slab)(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom, conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared with the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance. PMID:21148165

  5. Past and future application of solid-state detectors in manned spaceflight.

    PubMed

    Reitz, Guenther

    2006-01-01

    The radiation exposure in space missions can be reduced by careful mission planning and appropriate measures, such as provision of a radiation shelter, but it cannot be eliminated. The reason for that is the high penetration capability of the radiation components owing to their high energies. Radiation is therefore an acknowledged primary concern for manned spaceflight and is a potentially limiting factor for long-term orbital and interplanetary missions. The radiation environment is a complex mixture of charged particles of solar and galactic origin and of the radiation belts, as well as of secondary particles produced in interactions of the galactic cosmic particles with the nuclei of atmosphere of the earth. The complexity even increases by placing a spacecraft into this environment owing to the interaction of the radiation components with the shielding material. Therefore it is a challenge to provide for appropriate measurements in this radiation field, coping with the limited resources on experiment power and mass. Solid-state dosemeters were already chosen for measurements in the first manned flights. Thermoluminescence dosemeters (TLDs) and plastic nuclear track detectors (PNTD) especially found a preferred application because they are light-weighted, need no power supply and they are tissue-equivalent. Most of the data available until 1996 were gathered by using these passive detectors; this especially holds for heavy ion particle spectra. The systems, supplemented by converter foils or fission detectors and bubble detectors, provide information on dose, particle flux-, energy- and linear energy transfer spectra of the ionising radiation and neutron fluxes and doses. From 1989, silicon detectors were used for dose and flux measurements and later on for particle spectrometry. Silicon detectors were demonstrated as a powerful tool for the description of space radiation environment. Optical simulated luminescence (OSL) detectors have now been introduced as a new system in space research. Both, OSL and superheated drop detectors are candidates for personal dosimetry systems. The article will summarise past results, and results of measurements performed recently on the ISS, and conclude with future aspects. PMID:16766573

  6. The Development, Characterization, and Performance Evaluation of a New Combination Type Personnel Neutron Dosimeter

    NASA Astrophysics Data System (ADS)

    Liu, Chwei-Jeng

    A new combination type personnel neutron dosimeter has been designed and developed at the Oak Ridge National Laboratory (ORNL). The combination personnel neutron dosimeter (CPND) consists of a Harshaw albedo neutron thermoluminescent dosimeter (two pairs of TLD-600/TLD-700) and two bubble detectors (one BD-100R and one BDS-1500 from Bubble Technology Industries, Canada). The CPND was developed with the aim of having crude neutron spectrometric capability, universal applicability, better angular response, and an improved lower limit of detection (LLD). The CPND has been well characterized in the following areas: reusability, linearity, lower limit of detection (LLD), detection capability in mixed neutron-gamma fields, angular dependence, and neutron energy dependence. The characterization was accomplished with irradiations using a ^{238} Pu-Be source, a ^{252} Cf(D_2O) source, a ^{252}Cf source, a ^ {252}Cf(PE) source, monoenergetic neutrons from accelerator and reactor filtered beams, ^ {137}Cs, and X-rays. Optimum signal readout procedures, signal processing techniques, routine operational usage, and neutron dose equivalent evaluation algorithms for the CPND were developed with the goals of having the best precision and accuracy as well as being convenient to use. Various reference spectra were developed to evaluate the performance (mainly the spectrometric and the dose equivalent measurement capabilities) of the CPND. The performance of the CPND was evaluated by in-situ tests in radiation fields existing in the working environment at ORNL. The spectra in these areas were measured previously with a calibrated Bonner multisphere spectrometer. The CPND also was tested with laboratory radioisotopic sources in single-source and multi-source exposure situations. Finally, the CPND was tested by participating in the fourteenth Personnel Dosimetry Intercomparison Study. The results of the tests mentioned above demonstrated that the CPND meets the ambitious design purposes. Because of its 4 -interval spectrometric capability and high sensitivity, the CPND can be used, without prior knowledge of the spectrum or calibration in the field, to provide accurate dose equivalent estimates. The results of the detailed characterization and performance tests showed that the new CPND is an excellent personnel neutron dosimeter.

  7. Laser Stimulated Thermoluminescence

    NASA Astrophysics Data System (ADS)

    Abtahi, Abdollah

    Techniques for localized heating of semi-infinite single-layer and two-layer structures are investigated theoretically and experimentally, motivated by applications in thermoluminescence (TL) dosimetry of ionizing radiation. The heat-conduction equations are solved by the Green's function technique to obtain the transient temperature distribution caused by exposure to laser beams of Gaussian and uniform circular intensity profiles. It is shown that the spatio-temporal temperature response is readily monitored by the TL response that results when layer configuration contains a thermoluminescent phosphor. The experiments for the verification of the developed theory are performed with two specially constructed TL detection systems, one featuring a laser beam of Gaussian profile and the other a uniform circular laser beam. Measurements of the thermoluminescent emission from a number of different TL systems are performed and compared with computed responses on the basis of simple electron kinetics. We experiment exclusively with the commercial TL phosphor LiF:Mg,Ti(TLD-100, Harshaw), the most widely used material in thermoluminescence dosimetry. We study in detail localized Gaussian beam heating of it in the form of 0.9 mm thick slabs, self-supporting firms of fine-grain powder in a polyimide (Kapton) matrix, and on substrates of LiF single crystals or borosilicate glass. Thermoluminescent layers on glass substrates have been heated with Gaussian and uniform circular intensity profiles in two different modes: the laser beam impinges onto (a) the phosphor layer, and (b) the glass substrate. It is demonstrated that the optical and thermal behavior of the dosimeters can be determined by these methods and that, furthermore, the thermoluminescence response of a given configuration can be simulated as a function of a number of experimental parameters such as laser power, beam size, substrate and TL-layer thicknesses, and configuration of the dosimeters. In addition, we have investigated the dependence of the luminous efficiency (normalized thermoluminescence yield) and peak heights on heating rates in the range from 4 K/s to 5500 K/s. The efficiency values obtained are then included in the comparison of experimental and theoretical TL responses curves for various laser powers.

  8. Characterization of impurities in cubic boron nitride crystallites with thermoluminescence and ionoluminescence

    NASA Astrophysics Data System (ADS)

    Manfredotti, C.; Lo Giudice, A.; Paolini, C.; Vittone, E.; Fizzotti, F.; Cossio, R.

    2004-09-01

    IonoLuminescence (IL) and ThermoLuminescence (TL) techniques have been used in order to characterize the defects induced by doping due to different precursors in cubic boron nitride (c-BN) growth. Crystallites of dimensions of the order of 10-40 m obtained by HPHT (High Pressure and High Temperature) method were used. Protons microbeams of 2 MeV - corresponding to a penetration depth of 26 m in c-BN - with a spot diameter of few m, in connection with an ellipsoidal mirror characterized by a large light collection efficiency and a 0.25 m monochromator, allowed to acquire wide area luminescence spectra. We observed that IL spectra for samples characterized by a large Mg content, as obtained by PIXE (Particle Induced X-ray Emission) analysis, displayed three peaks at 1.95 eV, 3.2 eV and 3.9 eV respectively, while in samples with a large Ca content a fourth peak appeared around 1.7 eV. Even if the number of available samples was relatively low, a fair correlation was observed between the total area under the peaks at 1.7 and 1.95 eV and the total Ca content (up to 25 ppm) on one side and between the total area under the peak at 3.9 eV and the total Mg content (up to 100 ppm), even if this peak appeared with a much smaller intensity also in all the other samples. Moreover, TL measurements were carried out from RT up to 400 °C with a standard Harshaw TL reader after the exposure of samples to some Gy doses from a collimated -particle 241Am source. Specimens obtained by a Mg-based precursor did not show any thermoluminescence, while samples obtained by a Ca-based precursor showed a large and very reproducible TL spectrum. From the initial rise TL method, coupled to a preheating in order to separate the contributions from different traps, three series of centres were found out at 0.21, 0.35 and 0.6 eV. Samples obtained without a Ca-based precursor probably have a level at 0.45 eV instead of at 0.35 eV and, likely, there is also another level at 0.52 eV in Ca-doped platelets.

  9. SU-E-T-101: Determination and Comparison of Correction Factors Obtained for TLDs in Small Field Lung Heterogenous Phantom Using Acuros XB and EGSnrc

    SciTech Connect

    Soh, R; Lee, J; Harianto, F

    2014-06-01

    Purpose: To determine and compare the correction factors obtained for TLDs in 2 × 2cm{sup 2} small field in lung heterogenous phantom using Acuros XB (AXB) and EGSnrc. Methods: This study will simulate the correction factors due to the perturbation of TLD-100 chips (Harshaw/Thermoscientific, 3 × 3 × 0.9mm{sup 3}, 2.64g/cm{sup 3}) in small field lung medium for Stereotactic Body Radiation Therapy (SBRT). A physical lung phantom was simulated by a 14cm thick composite cork phantom (0.27g/cm{sup 3}, HU:-743 ± 11) sandwiched between 4cm thick Plastic Water (CIRS,Norfolk). Composite cork has been shown to be a good lung substitute material for dosimetric studies. 6MV photon beam from Varian Clinac iX (Varian Medical Systems, Palo Alto, CA) with field size 2 × 2cm{sup 2} was simulated. Depth dose profiles were obtained from the Eclipse treatment planning system Acuros XB (AXB) and independently from DOSxyznrc, EGSnrc. Correction factors was calculated by the ratio of unperturbed to perturbed dose. Since AXB has limitations in simulating actual material compositions, EGSnrc will also simulate the AXB-based material composition for comparison to the actual lung phantom. Results: TLD-100, with its finite size and relatively high density, causes significant perturbation in 2 × 2cm{sup 2} small field in a low lung density phantom. Correction factors calculated by both EGSnrc and AXB was found to be as low as 0.9. It is expected that the correction factor obtained by EGSnrc wlll be more accurate as it is able to simulate the actual phantom material compositions. AXB have a limited material library, therefore it only approximates the composition of TLD, Composite cork and Plastic water, contributing to uncertainties in TLD correction factors. Conclusion: It is expected that the correction factors obtained by EGSnrc will be more accurate. Studies will be done to investigate the correction factors for higher energies where perturbation may be more pronounced.

  10. Comparison of doses to the rectum derived from treatment planning system with in-vivo dose values in vaginal vault brachytherapy using cylinder applicators

    PubMed Central

    Obed, Rachel Ibhade; Akinlade, Bidemi Idayat; Ntekim, Atara

    2015-01-01

    Purpose In-vivo measurements to determine doses to organs-at-risk can be an essential part of brachytherapy quality assurance (QA). This study compares calculated doses to the rectum with measured dose values as a means of QA in vaginal vault brachytherapy using cylinder applicators. Material and methods At the Department of Radiotherapy, University College Hospital (UCH), Ibadan, Nigeria, intracavitary brachytherapy (ICBT) was delivered by a GyneSource high-dose-rate (HDR) unit with 60Co. Standard 2D treatment plans were created with HDR basic 2.6 software for prescription doses 5-7 Gy at points 5 mm away from the posterior surface of vaginal cylinder applicators (20, 25, and 30 mm diameters). The LiF:Mg, Ti thermoluminescent dosimeter rods (1 x 6 mm) were irradiated to a dose of 7 Gy on Theratron 60Co machine for calibration purpose prior to clinical use. Measurements in each of 34 insertions involving fourteen patients were performed with 5 TLD-100 rods placed along a re-usable rectal marker positioned in the rectum. The dosimeters were read in Harshaw 3500 TLD reader and compared with doses derived from the treatment planning system (TPS) at 1 cm away from the dose prescription points. Results The mean calculated and measured doses ranged from 2.1-3.8 Gy and 1.2-5.6 Gy with averages of 3.0 ± 0.5 Gy and 3.1 ± 1.1 Gy, respectively, for treatment lengths 2-8 cm along the cylinder-applicators. The mean values correspond to 48.9% and 50.8% of the prescribed doses, respectively. The deviations of the mean in-vivo doses from the TPS values ranged from –1.9 to 2.1 Gy with a p-value of 0.427. Conclusions This study was part of efforts to verify rectal dose obtained from the TPS during vaginal vault brachytherapy. There was no significant difference in the dose to the rectum from the two methods of measurements. PMID:26816506

  11. Maintaining the accuracy of the (60)Co calibration service at the ARPANSA post source replacement in 2010.

    PubMed

    Oliver, Chris; Butler, Duncan; Webb, David; Wright, Tracy; Lye, Jessica; Ramanathan, Ganesan; Harty, Peter; Takau, Viliami

    2015-06-01

    The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) maintains a (60)Co teletherapy source primarily for the calibration of therapy dosemeters. The source and encapsulating head were replaced in early 2010 with an Eldorado 78 head and new (60)Co source. In this article we present the results of ongoing accuracy and stability measurements since the replacement. A number of formal and informal indirect comparisons have been carried out with laboratories holding primary and secondary standards for (60)Co. ARPANSA chambers have also been calibrated at international primary standard laboratories allowing comparison of calibration coefficients and thus (60)Co absorbed dose standards. (60)Co calibration coefficients supplied by manufacturers of chambers were compared to those measured at the ARPANSA when this calibration was traceable to a primary standard. ARPANSA also participates in an annual international mailed dosimetry audit conducted by the International Atomic Energy Agency. The results thus far demonstrate that the absorbed doses to water delivered by the new ARPANSA (60)Co source are consistent with international doses within the stated uncertainties. PMID:25749989

  12. Assessment of the effective doses from two dental cone beam CT devices

    PubMed Central

    Schilling, R; Geibel, M-A

    2013-01-01

    Objectives: This study compares the effective dose for different fields of view (FOVs), resolutions and X-ray parameters from two cone beam CT units: the KaVo 3D (three-dimensional) eXam and the KaVo Pan eXam Plus 3D (KaVo Dental, Biberach, Germany). Methods: Measurements were made using thermoluminescent dosemeter chips in a radiation analog dosimetry head and neck phantom. The calculations of effective doses are based on the ICRP 60 and ICRP 103 recommendations of the International Commission on Radiological Protection. Results: Effective doses from the 3D eXam ranged between 32.8 µSv and 169.8 µSv, and for the Pan eXam Plus effective doses ranged between 40.2 µSv and 183.7 µSv; these were measured using ICRP 103 weighting factors in each case. The increase in effective dose between ICRP 60 and ICRP 103 recommendations averaged 157% for all measurements. Conclusions: Effective doses can be reduced significantly with the choice of lower resolutions and mAs settings as well as smaller FOVs to avoid tissues sensitive to radiation being inside the direct beam. Larger FOVs do not necessarily lead to higher effective doses. PMID:23420855

  13. Gafchromic film as a fast visual indicator of radiation exposure of first responders.

    PubMed

    Oren, Unal; Rf, Christopher L; Mattsson, Sren

    2012-06-01

    Three types of Gafchromic films have been studied to investigate their potential for use as a visually readable dosemeter for persons acting as first responders in connection with radiological or nuclear emergencies. The two most sensitive film types show a pronounced variation in sensitivity by photon energy and are therefore not suitable for use in cases of unknown exposures. The third film type tested (RTQA2), which is intended for quality control in radiation therapy has a sensitivity that is independent of the radiation quality, and is therefore considered as the most optimal for visual reading in situ. Tests carried out on a group of 10 human observers showed that absorbed doses down to 40 mGy can be detected by the eye. Read by a portable densitometer, qualitative absorbed dose estimates down to 9 mGy can be achieved. The colour change is obtained instantaneously, giving first responders immediate information about the presence of beta-, gamma- and X-ray radiation. PMID:21926417

  14. Natural radioactivity measurements in beach-rock samples of south-east coast of Tamilnadu, India.

    PubMed

    Ramasamy, V; Dheenathayalu, M; Ravisankar, R; Ponnusamy, V; Rajamanickkam, G Victor; Sahayam, DajKumar; Meenakshisundram, V; Gajendran, V

    2004-01-01

    The concentration of primordial radionuclides in beach-rock samples of the south-east coast of Tamilnadu, India has been measured using gamma ray spectrum of rock. The mean activities of 232Th, 238U and 40K are 144.18, 29.25 and 267.48 Bq kg(-1) respectively. In situ measurements were also carried out using environmental radiation dosemeter. The linear correlation coefficient was obtained. The average activity of concentration of 232Th in the present study is 2.5 times higher than the world median value while the activity of 238U and 40K were found to be lower. This may be due to the heavy minerals present in the study area. In the present study, the calculated activity ratio (Th/U) is higher than the crustal rocks. This may be due to changes in the crustal composition through time (mafic to felsic) that are reflected by a change in the Th and U abundances in sedimentary rocks, and also increase in carbon content with time resulted in the decrease in U content and increase in Th/U ratio. PMID:15266072

  15. Evaluation of dose from external irradiation for individuals living in areas affected by the Fukushima Daiichi Nuclear Plant accident.

    PubMed

    Naito, Wataru; Uesaka, Motoki; Yamada, Chie; Ishii, Hideki

    2015-02-01

    In order to effectively and appropriately manage external radiation doses in the affected areas of Fukushima, it is important to identify when, where and how much exposure occurred. It is also necessary to quantitatively measure external exposure and air dose rates for different activity patterns in individuals living and working in Japanese-style buildings. The authors used a new personal dosemeter (D-shuttle) along with a global positioning system and geographical information system to relate personal dose rate with activity patterns and air dose rate. Hourly individual doses obtained by D-shuttle can provide an effective communication tool for those who want to identify when and how much exposure occurs. Personal monitoring of 26 volunteers showed that personal doses obtained from D-shuttle were ?30% of cumulative air dose estimated by data from the airborne monitoring survey. This analysis showed that, for most study volunteers, the exposure from staying at home represented about half of the total cumulative dose. This suggests that even though the peak exposure doses may be observed outside of working hours, to develop appropriate countermeasures for external dose reduction, it is thus important to identify the contributions of individuals' time-activities. This study provides a valuable basis for developing a realistic and pragmatic method to estimate external doses of individuals in Fukushima. PMID:24982262

  16. Radiation Exposure to Patient and Staff in Hepatic Chemoembolization: Risk Estimation of Cancer and Deterministic Effects

    SciTech Connect

    Hidajat, Nico Wust, Peter; Felix, Roland; Schroeder, Ralf Juergen

    2006-10-15

    The purpose of the study was to determine the risks of radiation-induced cancer and deterministic effects for the patient and staff in transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC). Sixty-five patients with HCC underwent the first cycle of TACE. Thermoluminescence dosemeters and conversion factors were used to measure surface doses and to calculate organ doses and effective dose. For the patient, the risk of fatal cancer and severe genetic defect was in the magnitude of 10{sup -4} and 10{sup -5}, respectively. Five patients showed surface doses over the first lumbar vertebra exceeding 2000 mSv and 45 patients showed doses over the spine or the liver region above 500 mSv. The risk of fatal cancer and severe genetic defect for the radiologist and assistant was in the magnitude of 10{sup -7} to 10{sup -8}. They could exceed the threshold for lens opacity in the case of more than 490 and 1613 TACE yearly for a period of many years, respectively. Radiation dose could lead to local transient erythema and/or local depression of hematopoiesis in many patients after TACE. For the radiologist and assistant, risk of fatal cancer and genetic defect and lens opacity might arise when they perform interventions such as TACE intensively.

  17. Automation of film densitometry for application in personal monitoring.

    PubMed

    Taheri, M; Movafeghi, A; Rastkhah, N

    2011-03-01

    In this research work, a semi-automatic densitometry system has been developed for large-scale monitoring services by use of film badge dosemeters. The system consists of a charge-coupled device (CCD)-based scanner that can scan optical densities (ODs) up to 4.2, a computer vision algorithm to improve the quality of digitised films and an analyser program to calculate the necessary information, e.g. the mean OD of region of interest and radiation doses. For calibration of the system, two reference films were used. The Microtek scanner International Color Consortium (ICC) profiler is applied for determining the colour attributes of the scanner accurately and a reference of the density step tablet, Bundesanstalt fr Materialforschung und-prfung (BAM) is used for calibrating the automatic conversion of gray-level values to OD values in the range of 0.2-4.0 OD. The system contributes to achieve more objectives and reliable results. So by applying this system, we can digitise a set of 20 films at once and calculate their relative doses less than about 4 min, and meanwhile it causes to avoid disadvantages of manual process and to enhance the accuracy of dosimetry. PMID:21199823

  18. Monitoring the eye lens: how do the international organisations react?

    PubMed

    Behrens, R

    2015-04-01

    The International Commission on Radiological Protection (ICRP) has recommended to lower the limit of the dose to the eye lens for occupationally exposed persons to a mean value of 20 mSv y(-1) (averaged over 5 y, with a maximum of 50 mSv y(-1)); already in the autumn of 2011, both the European Commission and the International Atomic Energy Agency : IAEA) took over this reduction in their respective draft basic safety standards. Even prior to this (and since then, increasingly so), several international activities were started (among other things, the following ones): (1) the ICRP adopted a stylised model of the eye to calculate dose conversion coefficients for its report ICRP 116; (2) the European Commission has funded the ORAMED project dealing with radiation protection in medicine; (3) in its standard IEC 62387 on passive dosimetry systems, the International Electrotechnical Commission (IEC) has laid down requirements for Hp(3) eye dosemeters; (4) the International Organization for Standardization (ISO) and the IAEA provide a range of practical advice in the standard ISO 15382 (still a draft) and in a technical document IAEA TecDoc on both radiation protection and on dosimetry; (5) for most cases, the International Commission on Radiation Units and Measurements (ICRU) recommends both phantoms (the slab and the cylinder). In short: most national procedures can orientate themselves on international ones; some questions, however, remain open. PMID:25213264

  19. Ambient dose and dose rate measurements in the vicinity of Elekta Precise accelerators for radiation therapy.

    PubMed

    Zutz, H; Hupe, O

    2014-12-01

    In radiation therapy, commercially available medical linear accelerators (LINACs) are used. At high primary beam energies in the 10-MeV range, the leakage dose of the accelerator head and the backscatter from the room walls, the air and the patient become more important. Therefore, radiation protection measurements of photon dose rates in the treatment room and in the maze are performed to quantify the radiation field. Since the radiation of the LINACs is usually pulsed with short radiation pulse durations in the microsecond range, there are problems with electronic dose (rate) meters commonly used in radiation protection. In this paper measurements with ionisation chambers are presented and electronic dosemeters are used for testing at selected positions. The measured time-averaged dose rate ranges from a few microsieverts per hour in the maze to some millisieverts per hour in the vicinity of the accelerator head and up to some sieverts per hour in the blanked primary beam and several hundred sieverts per hour in the direct primary beam. PMID:24379437

  20. Reliability in individual monitoring service.

    PubMed

    Mod Ali, N

    2011-03-01

    As a laboratory certified to ISO 9001:2008 and accredited to ISO/IEC 17025, the Secondary Standard Dosimetry Laboratory (SSDL)-Nuclear Malaysia has incorporated an overall comprehensive system for technical and quality management in promoting a reliable individual monitoring service (IMS). Faster identification and resolution of issues regarding dosemeter preparation and issuing of reports, personnel enhancement, improved customer satisfaction and overall efficiency of laboratory activities are all results of the implementation of an effective quality system. Review of these measures and responses to observed trends provide continuous improvement of the system. By having these mechanisms, reliability of the IMS can be assured in the promotion of safe behaviour at all levels of the workforce utilising ionising radiation facilities. Upgradation of in the reporting program through a web-based e-SSDL marks a major improvement in Nuclear Malaysia's IMS reliability on the whole. The system is a vital step in providing a user friendly and effective occupational exposure evaluation program in the country. It provides a higher level of confidence in the results generated for occupational dose monitoring of the IMS, thus, enhances the status of the radiation protection framework of the country. PMID:21147789

  1. Dose distribution for dental cone beam CT and its implication for defining a dose index

    PubMed Central

    Pauwels, R; Theodorakou, C; Walker, A; Bosmans, H; Jacobs, R; Horner, K; Bogaerts, R

    2012-01-01

    Objectives To characterize the dose distribution for a range of cone beam CT (CBCT) units, investigating different field of view sizes, central and off-axis geometries, full or partial rotations of the X-ray tube and different clinically applied beam qualities. The implications of the dose distributions on the definition and practicality of a CBCT dose index were assessed. Methods Dose measurements on CBCT devices were performed by scanning cylindrical head-size water and polymethyl methacrylate phantoms, using thermoluminescent dosemeters, a small-volume ion chamber and radiochromic films. Results It was found that the dose distribution can be asymmetrical for dental CBCT exposures throughout a homogeneous phantom, owing to an asymmetrical positioning of the isocentre and/or partial rotation of the X-ray source. Furthermore, the scatter tail along the z-axis was found to have a distinct shape, generally resulting in a strong drop (90%) in absorbed dose outside the primary beam. Conclusions There is no optimal dose index available owing to the complicated exposure geometry of CBCT and the practical aspects of quality control measurements. Practical validation of different possible dose indices is needed, as well as the definition of conversion factors to patient dose. PMID:22752320

  2. Neutron field characterisation of the OB26 CRNA irradiator in view of its use for calibration purposes.

    PubMed

    Mazrou, Hakim; Sidahmed, Tassadit; Allab, Malika

    2010-09-01

    The main goal of the present work is to characterise the neutron field of an OB26 irradiation system acquired by the Nuclear Research Center of Algiers for radiation protection purposes. Extensive Monte-Carlo (MC) calculations and measurements using BF(3)- and (3)He-based neutron area dosemeters were performed to estimate the contribution, on the energy neutron spectrum, of each component present in the bunker facility of the Algerian Secondary Standard Dosimetry Laboratory (SSDL) where the irradiator has been installed. For this purpose, new irradiation configurations based on the (241)Am-Be source placed in the OB 26/2 biological shielding inside its environment have been investigated by MC simulations, and comparison with the ISO spectrum has been performed. During MC simulations, sensitivity analysis has been considered to estimate the effect of several physical parameters on the neutron fluence and dose equivalent rates. In addition, the contribution of the gamma dose equivalent rates to the total neutron dose equivalent rates was estimated for both selected source-detector distances (SDDs) 150 and 200 cm. Finally, a theoretical approach has been adopted, using MCNP5 fluence rates, to estimate the readings of the instruments taking into account their response functions. A low mean difference (12 %) between measured and predicted dose equivalent rates for two selected SDDs has been observed. Overall, the obtained MCNP5 results regarding the actual SSDL irradiation facility are particularly encouraging, but need to be supported by further experimental data. PMID:20554579

  3. Results of the regional intercomparison exercise for the determination of operational quantity HP(10) in Latin America.

    PubMed

    Saraví, M; Zaretzky, A; Lindner, C; Díaz, J; Walwyn, G; Amorim, R; De Souza, D; Gregori, B; Papadópulos, S; Meghzifene, A; Ferruz, P; Suárez, R Cruz

    2007-01-01

    Several intercomparison exercises were organised by the International Atomic Energy Agency (IAEA) on the determination of operational quantities at the regional or interregional basis. In the Latin American region an intercomparison for the determination of the operational quantity Hp(10) was completed mid-2004, as a follow-up to previous exercises carried out during the 1990s. Eighteen individual external monitoring services from nineteen Member States participated in the first phase. The second phase grouped 15 services that had participated in the first phase. Dosemeter irradiations in photon beams were done by four Secondary Standard Dosimetry Laboratories (SSDLs) of the region. The preparation of this exercises involved an audit by the IAEA SSDL, where reference irradiations were provided to all participants for verification of their systems. During the first phase (2002-2003) only 9 out of 18 services met the performance requirements for such monitoring services. Necessary corrective actions and procedure verification were implemented. During the second phase (2004) 11 out of 15 services fulfilled the performance criteria. This intercomparison shows that there has been improvement in the second phase and most participants demonstrated a satisfactory performance of the quantity tested. PMID:17182603

  4. Characteristics of the neutron field of the facility at DIN-UPM.

    PubMed

    Gallego, E; Lorente, A; Vega-Carrillo, H R

    2004-01-01

    A new source facility (241Am-Be) has been installed in a bunker-type room of large dimensions. To characterise the neutron fields in the facility, detailed calculations have been made with MCNP-4C, showing the different components of the neutron radiation reaching the reference points (direct, inscattered, backscattered). The contribution from neutrons scattered in the walls to the total ambient dose equivalent remains reasonably low (<10%) in the reference points. Additionally, spectra measurements have been performed with a Bonner spheres spectrometer with a 6LiI(Eu) scintillator (0.4 phi x 0.4 cm2), UTA4 response matrix and BUNKIUT unfolding code. The calculated and experimentally obtained spectra are compared, with small differences found in the epithermal and thermal region, attributable to the concrete composition used in the calculations. The H*(10) rate has been determined from the spectra, and then compared to the reading of an active dosemeter (LB6411), with differences found lower than 8%. PMID:15353625

  5. Neutron measurements in a Varian 2,100C LINAC facility using a Bonner sphere system based on passive gold activation detectors.

    PubMed

    Fernández, F; Domingo, C; Amgarou, K; Castelo, J; Bouassoule, T; Garcia, M J; Luguera, E

    2007-01-01

    The use of high-energy linear electron accelerators (LINACs) for medical cancer treatments is widespread on an international scale. The associated bremsstrahlung X rays may produce neutrons as a result of subsequent photonuclear reactions with the different materials constituting the accelerator head. The generated neutron field is highly variable and depends strongly on the beam energy, on the accelerator shielding, on the flattering filter as well as on the movable collimators (jaws) design and on the irradiation field geometry. An estimate of this photoneutron component is, thus, of practical interest to quantify the radiological risk for the working staff and patients. Due to high frequency electromagnetic fields, and also to the presence of abundant leaked and scattered photons in these installations, measurements of the corresponding neutron fields by active dosemeters are extremely difficult. A modified version of the Bonner sphere system, based on passive gold activation detectors, has been used to perform neutron measurements at two points in a Varian 2,100C LINAC facility. A home-made unfolding procedure (CDM) has been utilised to determine the neutron spectra present at the measurement points. Results indicate that the giant dipole resonance process is the most adequate model to explain neutron production in the LINAC and that a thermal component is present at the measurement points. PMID:17525060

  6. 1983 international intercomparison of nuclear accident dosimetry systems at Oak Ridge National Laboratory

    SciTech Connect

    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.

  7. Radiation measurements around X-ray cabinet systems.

    PubMed

    Suric Mihic, M; Vucic, Z; Prlic, I; Lulic, I; Mestrovic, T

    2012-07-01

    Security personnel who operate X-ray units for the control of hand luggage and personal items at airports are generally not under dosimetric surveillance. A significant increase in the number of inspected items per passenger, due to rigorous air traffic security measures, raises a question of extended exposure of these workers to scattered X-ray radiation. A new approach to investigating directions of breaches of scattered X-ray radiation in the area near to an X-ray cabinet system, which is based on using active electronic dosemeters is presented. Influence of the increase in the number of inspected items in time on the dose rate is described. Time-dependent dose rates have showed a very good correlation with passengers undergoing security control prior to boarding an airplane. Measurements confirmed that an increase in the dose rate, coinciding with rush hours, was caused by scattered radiation passing through incompletely closed lead curtains. It is found that the doses at the entrance to the inspection tunnel are 50% higher than those at the exit, which is a consequence of inherent operational characteristics of X-ray cabinet systems. PMID:22302108

  8. Experimental simulation of personal dosimetry in production of medical radioisotopes by research reactor.

    PubMed

    Mossadegh, N; Karimian, A; Shahhosseini, E; Mohammadzadeh, A; Sheibani, Sh

    2011-09-01

    Due to their work conditions, research reactor personnel are exposed to ionising nuclear radiations. Because the absorbed dose values are different for different tissues due to variations in sensitivity, in this work personal dosimetry has been performed under normal working conditions at anatomical locations relevant to more sensitive tissues as well as for the whole body by employing a Rando phantom and thermoluminescent dosemeters (TLDs). Fifty-two TLDs-100H were positioned at high-risk organ locations such as the thyroid, eyes as well as the left breast, which was used to assess the whole-body dose in order to study the absorbed doses originating from selected locations in the vicinity of the reactor. The results have employed the tissue weighting factors based on International Commission on Radiological Protection ICRP 103 and ICRP 60 and the measured results were below the dose limits recommended by ICRP. The mean effective dose rates calculated from ICRP 103 were the following: whole body, 30.64-6.44 Sv h(-1); thyroid, 1.22-0.23 Sv h(-1); prostate, 0.085-0.045 Sv h(-1); gonads, 1.00-0.51 Sv h(-1); breast, 3.68-0.77 Sv h(-1); and eyes, 33.74-7.01 Sv h(-1). PMID:21862507

  9. Comparison of different PADC materials for neutron dosimetry.

    PubMed

    Mayer, S; Boschung, M

    2014-10-01

    Investigations on track density and track size distributions of different PADC (poly allyl diglycol carbonate) materials have been performed. The PADC used for the tests has been produced by Thermo Electron (USA), Track Analysis System Limited (UK), Chiyoda Technol Corporation (Japan) and Intercast srl (Italy). For each PADC material 120 detectors were randomly selected out of 2 sheets: 60 detectors from one sheet have been irradiated with a personal dose equivalent of 3 mSv in the field of a (241)Am-Be source at the calibration laboratory of PSI, whilst the other 60 detectors from the other sheet have been used as background samples. All detectors have been processed according to an identical etching procedure and have been analysed with TASLImage scanning system. For each set of detectors the value of the average background signal, the average neutron sensitivity and the detection limit with respect to a personal dose equivalent measured with a dosemeter based on PADC have been determined. The results of the investigations allowed a comparison of the neutron sensitivity and background signal behaviours of PADC materials from different manufacturers and the assessment of the variation of neutron sensitivity and background signal over a single sheet. PMID:24097314

  10. Microdosemeter instrument (MIDN) for assessing risk in space.

    PubMed

    Pisacane, V L; Dolecek, Q E; Malak, H; Cucinotta, F A; Zaider, M; Rosenfeld, A B; Rusek, A; Sivertz, M; Dicello, J F

    2011-02-01

    Radiation in space generally produces higher dose rates than that on the Earth's surface, and contributions from primary galactic and solar events increase with altitude within the magnetosphere. Presently, no personnel monitor is available to astronauts for real-time monitoring of dose, radiation quality and regulatory risk. This group is developing a prototypic instrument for use in an unknown, time-varying radiation field. This microdosemeter-dosemeter nucleon instrument is for use in a spacesuit, spacecraft, remote rover and other applications. It provides absorbed dose, dose rate and dose equivalent in real time so that action can be taken to reduce exposure. Such a system has applications in health physics, anti-terrorism and radiation-hardening of electronics as well. The space system is described and results of ground-based studies are presented and compared with predictions of transport codes. An early prototype in 2007 was successfully launched, the only solid-state microdosemeter to have flown in space. PMID:21199825

  11. Survey of radon and thoron in homes of Indian Himalaya.

    PubMed

    Ramola, Rakesh Chand

    2011-07-01

    Measurements of radon, thoron and their progeny were carried out in some houses from Garhwal and Kumaun Himalayas of India using a LR-115 plastic track detector. The measurements were made in various residential houses of the area at a height of 2.5 m above the ground level using a twin chamber radon dosemeter, which can record the values of radon, thoron and their progeny separately. The concentrations of radon and thoron in these homes were found to vary from 11 to 191 and 1 to 156 Bq m(-3), respectively. The equilibrium factor between radon and progeny varies from 0.02 to 0.90, with an average of 0.26 for the region. The resulting dose rate due to radon, thoron and their decay products was found to vary from 0.02 to 0.84 ?Sv h(-1) with an arithmetic mean of 0.27 ?Sv h(-1). A detailed analysis of the distribution of radon, thoron and their decay products inside a house is also reported. The observed dose rates due to radon, thoron and progeny were found somewhat higher but well below the international recommendations. PMID:21486831

  12. Bubble-detector measurements in the Russian segment of the International Space Station during 2009-12.

    PubMed

    Smith, M B; Khulapko, S; Andrews, H R; Arkhangelsky, V; Ing, H; Lewis, B J; Machrafi, R; Nikolaev, I; Shurshakov, V

    2015-01-01

    Measurements using bubble detectors have been performed in order to characterise the neutron dose and energy spectrum in the Russian segment of the International Space Station (ISS). Experiments using bubble dosemeters and a bubble-detector spectrometer, a set of six detectors with different energy thresholds that is used to determine the neutron spectrum, were performed during the ISS-22 (2009) to ISS-33 (2012) missions. The spectrometric measurements are in good agreement with earlier data, exhibiting expected features of the neutron energy spectrum in space. Experiments using a hydrogenous radiation shield show that the neutron dose can be reduced by shielding, with a reduction similar to that determined in earlier measurements using bubble detectors. The bubble-detector data are compared with measurements performed on the ISS using other instruments and are correlated with potential influencing factors such as the ISS altitude and the solar activity. Surprisingly, these influences do not seem to have a strong effect on the neutron dose or energy spectrum inside the ISS. PMID:24714114

  13. Novel shielding materials for space and air travel.

    PubMed

    Vana, N; Hajek, M; Berger, T; Fugger, M; Hofmann, P

    2006-01-01

    The reduction of dose onboard spacecraft and aircraft by appropriate shielding measures plays an essential role in the future development of space exploration and air travel. The design of novel shielding strategies and materials may involve hydrogenous composites, as it is well known that liquid hydrogen is most effective in attenuating charged particle radiation. As precursor for a later flight experiment, the shielding properties of newly developed hydrogen-rich polymers and rare earth-doped high-density rubber were tested in various ground-based neutron and heavy ion fields and compared with aluminium and polyethylene as reference materials. Absorbed dose, average linear energy transfer and gamma-equivalent neutron absorbed dose were determined by means of LiF:Mg,Ti thermoluminescence dosemeters and CR-39 plastic nuclear track detectors. First results for samples of equal aerial density indicate that selected hydrogen-rich plastics and rare-earth-doped rubber may be more effective in attenuating cosmic rays by up to 10% compared with conventional aluminium shielding. The appropriate adaptation of shielding thicknesses may thus allow reducing the biologically relevant dose. Owing to the lower density of the plastic composites, mass savings shall result in a significant reduction of launch costs. The experiment was flown as part of the European Space Agency's Biopan-5 mission in May 2005. PMID:16717109

  14. Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate.

    PubMed

    Kowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro

    2014-12-01

    The 6- to 7-MeV high-energy gamma-ray calibration field by the (19)F(p, ??)(16)O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma-ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. PMID:24446508

  15. Indoor radon levels in urban Hyderabad area, Andhra Pradesh, India.

    PubMed

    Sreenath Reddy, M; Yadagiri Reddy, P; Rama Reddy, K; Eappen, K P; Ramachandran, T V; Mayya, Y S

    2008-01-01

    Indoor radon levels in urban areas of Hyderabad, Andhra Pradesh, India were measured by a time integrated method using solid state nuclear track detector-based dosemeters. Results show that the radon levels varied widely in the area ranging from 17 to 311 Bq m(-3) with a geometric mean value of 52.8 Bq m(-3) (GSD=1.7). Cumulative frequency distribution of radon levels gave a best fit on a log-normal scale. Measurements were carried out for 1 y, segregating the measurement periods in accordance with seasonal changes. Soil samples from the region were also analysed for natural radionuclides to study its effect, if any, on indoor radon levels. Dwellings categorised based on construction types showed that the average radon levels in the order tiles (TLE)>asbestos (ASB)>concrete (RCC) for the roof structures. The estimated radon levels in the study area are relatively higher than the country's average value of 23 Bq m(-3) and global average value of 30 Bq m(-3). PMID:19122001

  16. Evaluation of a real-time display for skin dose map in cardiac catheterisation procedures.

    PubMed

    Sanchez, Roberto M; Vano, Eliseo; Fernandez, Jose M; Escaned, Javier

    2015-07-01

    The purpose of this work was to validate a prototype designed to display skin dose maps in real time for clinicians that perform interventional cardiology procedures. Measurements using copper absorbers and three kinds of dosemeters (solid-state, radiochromic film and optically stimulated luminescence) were performed in a catheterisation laboratory. Some clinical results are also discussed. The system provides patient skin doses with acceptable accuracy, taking into account couch shifts, wedge compensation filters and collimation. The greatest source of uncertainty is that resulting from patient shape modelling. From a set of 374 patients recorded, it can be concluded that the peak skin dose (PSD) for patients with the same cumulative air kerma at the patient entrance reference point can be rather different. This real-time skin dose calculator has resulted easier to manage for measuring patient PSDs than other methods based on films or CR plates. As well as an improvement for patient safety, it could prove a useful training tool for clinicians. PMID:25788618

  17. Effectiveness of thyroid gland shielding in dental CBCT using a paediatric anthropomorphic phantom

    PubMed Central

    Davies, J; Horner, K; Theodorakou, C

    2015-01-01

    Objectives: The purpose of the study is to evaluate the effectiveness of thyroid shielding in dental CBCT examinations using a paediatric anthropomorphic phantom. Methods: An ATOM® 706-C anthropomorphic phantom (Computerized Imaging Reference Systems Inc., Norfolk, VA) representing a 10-year-old child was loaded with six thermoluminescent dosemeters positioned at the level of the thyroid gland. Absorbed doses to the thyroid were measured for five commercially available thyroid shields using a large field of view (FOV). Results: A statistically significant thyroid gland dose reduction was found using thyroid shielding for paediatric CBCT examinations for a large FOV. In addition, a statistically significant difference in thyroid gland doses was found depending on the position of the thyroid gland. There was little difference in the effectiveness of thyroid shielding when using a lead vs a lead-equivalent thyroid shield. Similar dose reduction was found using 0.25- and 0.50-mm lead-equivalent thyroid shields. Conclusions: Thyroid shields are to be recommended when undertaking large FOV CBCT examinations on young patients. PMID:25411710

  18. Preparation and characterisation of a sol-gel process ?-Al?O? polycrystalline detector.

    PubMed

    Ferreira, H R; Santos, A

    2015-02-01

    This article presents the dosimetric characteristics of ?-Al2O3 detectors prepared through the sol-gel process, disc pressing and sintering in a highly reducing atmosphere. Comparative tests between the sol-gel process ?-Al2O3 polycrystalline and anion-defective ?-Al2O3:C single-crystal detectors indicate that the ones prepared through this approach present good dosimetric characteristics similar to those found in single-crystal detectors, such as a simple glow curve with the main peak at ?198 C (2 C s(-1)), high sensitivity, a detection threshold of 1.7 Gy, linearity of response, low fading, relatively low photon energy dependence, reusability without annealing and good reproducibility. However, the undesirable feature of heating rate dependence of the thermoluminescence (TL) output in ?-Al2O3:C single crystal is practically non-existent in the sol-gel process ?-Al2O3 polycrystalline detector. This characteristic renders it useful for the routine processing of large numbers of personal and environmental dosemeters at higher heating rates and also when it comes to the proposal for new approaches to thermal quenching investigation. PMID:24795396

  19. Occupational dose constraints in interventional cardiology procedures: the DIMOND approach

    NASA Astrophysics Data System (ADS)

    Tsapaki, Virginia; Kottou, Sophia; Vano, Eliseo; Komppa, Tuomo; Padovani, Renato; Dowling, Annita; Molfetas, Michael; Neofotistou, Vassiliki

    2004-03-01

    Radiation fields involved in angiographic suites are most uneven with intensity and gradient varying widely with projection geometry. The European Commission DIMOND III project addressed among others, the issues regarding optimization of staff doses with an attempt to propose preliminary occupational dose constraints. Two thermoluminescent dosemeters (TLD) were used to assess operators' extremity doses (left shoulder and left foot) during 20 coronary angiographies (CAs) and 20 percutaneous transluminal coronary angioplasties (PTCAs) in five European centres. X-ray equipment, radiation protection measures used and the dose delivered to the patient in terms of dose-area product (DAP) were recorded so as to subsequently associate them with operator's dose. The range of staff doses noted for the same TLD position, centre and procedure type emphasizes the importance of protective measures and technical characteristics of x-ray equipment. Correlation of patient's DAP with staff shoulder dose is moderate whereas correlation of patient's DAP with staff foot dose is poor in both CA and PTCA. Therefore, it is difficult to predict operator's dose from patient's DAP mainly due to the different use of protective measures. A preliminary occupational dose constraint value was defined by calculating cardiologists' annual effective dose and found to be 0.6 mSv.

  20. Study of the impact of artificial articulations on the dose distribution under medical irradiation

    NASA Astrophysics Data System (ADS)

    Buffard, E.; Gschwind, R.; Makovicka, L.; Martin, E.; Meunier, C.; David, C.

    2005-02-01

    Perturbations due to the presence of high density heterogeneities in the body are not correctly taken into account in the Treatment Planning Systems currently available for external radiotherapy. For this reason, the accuracy of the dose distribution calculations has to be improved by using Monte Carlo simulations. In a previous study, we established a theoretical model by using the Monte Carlo code EGSnrc [I. Kawrakow, D.W.O. Rogers, The EGSnrc code system: MC simulation of electron and photon transport. Technical Report PIRS-701, NRCC, Ottawa, Canada, 2000] in order to obtain the dose distributions around simple heterogeneities. These simulations were then validated by experimental results obtained with thermoluminescent dosemeters and an ionisation chamber. The influence of samples composed of hip prostheses materials (titanium alloy and steel) and a substitute of bone were notably studied. A more complex model was then developed with the Monte Carlo code BEAMnrc [D.W.O. Rogers, C.M. MA, G.X. Ding, B. Walters, D. Sheikh-Bagheri, G.G. Zhang, BEAMnrc Users Manual. NRC Report PPIRS 509(a) rev F, 2001] in order to take into account the hip prosthesis geometry. The simulation results were compared to experimental measurements performed in a water phantom, in the case of a standard treatment of a pelvic cancer for one of the beams passing through the implant. These results have shown the great influence of the prostheses on the dose distribution.

  1. Evaluation of staff, patient and foetal radiation doses due to endoscopic retrograde cholangiopancreatography (ERCP) procedures in a pregnant patient.

    PubMed

    Huda, A; Garzón, W J; Filho, G C L; Vieira, B; Kramer, R; Xu, X G; Gao, Y; Khoury, H J

    2016-03-01

    The use of endoscopic retrograde cholangiopancreatography (ERCP) in pregnant patients is not rare. Most studies on the safety and efficacy of these procedures report short- and long-term pregnancy outcomes and but not foetal absorbed doses. This investigation reports on an ERCP procedure for a 40-y-old woman who was 32-34 weeks pregnant. Thermoluminescent dosemeters (TLD 100) were used to measure doses received by the patient and the staff. Additionally, Monte Carlo calculations were performed using a 3D computational phantom representing a 9-month pregnant patient to estimate the foetal absorbed dose. The results show that the spleen of the mother received the largest absorbed dose of 12.18 mGy since it was closer to the source than other internal organs. For the foetus and uterus, the lowest absorbed dose was found to be 0.01 mGy to the foetal brain, while the largest absorbed dose was estimated to be 0.13 mGy to the placenta. PMID:26084305

  2. Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule.

    PubMed

    Pugliese, M; Bengin, V; Casolino, M; Roca, V; Zanini, A; Durante, M

    2010-08-01

    Radiation assessment and protection in space is the first step in planning future missions to the Moon and Mars, where mission and number of space travelers will increase and the protection of the geomagnetic shielding against the cosmic radiation will be absent. In this framework, the shielding effectiveness of two flexible materials, Kevlar and Nextel, were tested, which are largely used in the construction of spacecrafts. Accelerator-based tests clearly demonstrated that Kevlar is an excellent shield for heavy ions, close to polyethylene, whereas Nextel shows poor shielding characteristics. Measurements on flight performed onboard of the International Space Station and of the Foton-M3 capsule have been carried out with special attention to the neutron component; shielded and unshielded detectors (thermoluminescence dosemeters, bubble detectors) were exposed to a real radiation environment to test the shielding properties of the materials under study. The results indicate no significant effects of shielding, suggesting that thin shields in low-Earth Orbit have little effect on absorbed dose. PMID:20364264

  3. Dosimetric study of mandible examinations performed with three cone-beam computed tomography scanners.

    PubMed

    Khoury, Helen J; Andrade, Marcos E; Araujo, Max Well; Brasileiro, Izabela V; Kramer, Richard; Huda, Amir

    2015-07-01

    The objective of this work was to evaluate the air kerma-area product (PKA) and the skin absorbed dose in the region of the eyes, salivary glands and thyroid of the patient from mandible examinations performed with three cone-beam computed tomography (CBCT) scanners, i.e. i-CAT classic, Gendex CB-500 and PreXion 3D. For the dosimetric evaluation, an anthropomorphic head phantom (model RS-250) was used to simulate an adult patient. The CBCT examinations were performed using standard and high-resolution protocols for mandible acquisitions for adult patients. During the phantom's exposure, the PKA was measured using an ionising chamber and the absorbed doses to the skin in the region of the eyes, thyroid and salivary glands were estimated using thermoluminescence dosemeters (TLDs) positioned on the phantom's surface. The PKA values estimated with the CBCT scanners varied from 26 to 138 Gy m(2). Skin absorbed doses in the region of the eyes varied from 0.07 to 0.34 mGy; at the parotid glands, from 1.31 to 5.93 mGy; at the submandibular glands, from 1.41 to 6.86 mGy; and at the thyroid, from 0.18 to 2.45 mGy. PKA and absorbed doses showed the highest values for the PreXion 3D scanner due to the use of the continuous exposure mode and a high current-time product. PMID:25897144

  4. Effective dose from cone beam CT examinations in dentistry.

    PubMed

    Roberts, J A; Drage, N A; Davies, J; Thomas, D W

    2009-01-01

    Cone beam CT (CBCT) is becoming an increasingly utilized imaging modality for dental examinations in the UK. Previous studies have presented little information on patient dose for the range of fields of view (FOVs) that can be utilized. The purpose of the study was therefore to calculate the effective dose delivered to the patient during a selection of CBCT examinations performed in dentistry. In particular, the i-CAT CBCT scanner was investigated for several imaging protocols commonly used in clinical practice. A Rando phantom containing thermoluminescent dosemeters was scanned. Using both the 1990 and recently approved 2007 International Commission on Radiological Protection recommended tissue weighting factors, effective doses were calculated. The doses (E(1990), E(2007)) were: full FOV head (92.8 microSv, 206.2 microSv); 13 cm scan of the jaws (39.5 microSv, 133.9 microSv); 6 cm high-resolution mandible (47.2 microSv, 188.5 microSv); 6 cm high-resolution maxilla (18.5 microSv, 93.3 microSv); 6 cm standard mandible (23.9 microSv, 96.2 microSv); and 6 cm standard maxilla (9.7 microSv, 58.9 microSv). The doses from CBCT are low compared with conventional CT but significantly higher than conventional dental radiography techniques. PMID:18852212

  5. Photoneutron contamination from an 18 MV Saturne medical linear accelerator in the treatment room.

    PubMed

    Khosravi, Mostafa; Shahbazi-Gahrouei, Daryoush; Jabbari, Keyvan; Nasri-Nasrabadi, Mehdi; Baradaran-Ghahfarokhi, Milad; Siavashpour, Zahra; Gheisari, Ruhollah; Amiri, Behnam

    2013-09-01

    Dose escalation with high-energy X rays of medical linear accelerators (linacs) in radiotherapy offers several distinct advantages over the lower energy photons. However, owing to photoneutron reactions, interaction of high-energy photons (>8 MV) with various high-Z nuclei of the materials in the linac head components produces unavoidable neutrons. The aim of this study was to evaluate the photoneutron dose equivalent per unit therapeutic X-ray dose of 18 MV, GE Saturne 20 linac in the treatment room using Monte Carlo (MC) MCNP linac head full simulation as well as thermoluminescence dosemeter measurements. This machine is one of the old linac models manufactured by General Electric Company; however, it is widely used in the developing countries because of low cost and simple maintenance for radiotherapy applications. The results showed a significant photoneutron dose from Saturne 20 linac head components especially at distances near the linac head (<150 cm). Results of this work could be used in several applications, especially designing bunker and entrance door shielding against neutrons produced by photoneutron reactions in GE Saturne 20. However, a detailed cost optimisation for a specific room would require a dedicated calculation. PMID:23538892

  6. Characterization of neutron calibration fields at the TINT's 50 Ci americium-241/beryllium neutron irradiator

    NASA Astrophysics Data System (ADS)

    Liamsuwan, T.; Channuie, J.; Ratanatongchai, W.

    2015-05-01

    Reliable measurement of neutron radiation is important for monitoring and protection in workplace where neutrons are present. Although Thailand has been familiar with applications of neutron sources and neutron beams for many decades, there is no calibration facility dedicated to neutron measuring devices available in the country. Recently, Thailand Institute of Nuclear Technology (TINT) has set up a multi-purpose irradiation facility equipped with a 50 Ci americium-241/beryllium neutron irradiator. The facility is planned to be used for research, nuclear analytical techniques and, among other applications, calibration of neutron measuring devices. In this work, the neutron calibration fields were investigated in terms of neutron energy spectra and dose equivalent rates using Monte Carlo simulations, an in-house developed neutron spectrometer and commercial survey meters. The characterized neutron fields can generate neutron dose equivalent rates ranging from 156 μSv/h to 3.5 mSv/h with nearly 100% of dose contributed by neutrons of energies larger than 0.01 MeV. The gamma contamination was less than 4.2-7.5% depending on the irradiation configuration. It is possible to use the described neutron fields for calibration test and routine quality assurance of neutron dose rate meters and passive dosemeters commonly used in radiation protection dosimetry.

  7. Studies on automatic hot gas reader used in the countrywide personnel monitoring programme.

    PubMed

    Kumar, Munish; Alagu Raja, E; Prasad, L C; Popli, K L; Kher, R K; Bhatt, B C

    2005-01-01

    In India, approximately 58,000 radiation workers are monitored using locally made CaSO4:Dy teflon embedded thermoluminescence dosemeter (TLD) badge system. The automatic hot gas readers developed locally are also used in TL measurements. The hot gas reader system has many advantages over the manual readers used previously and has completely replaced the manual reader system in all TLD personnel monitoring units in India. In the present study, the new reader system is studied and a theoretical attempt has been made to interpret the experimentally obtained results. The glow curves are generated theoretically and are also plotted experimentally. It has been found that the heat capacity of the heating gas, which is responsible for the transfer of heat, has a role in deciding the position of peak and is verified experimentally using different gas flow rates of nitrogen and argon as heating gases in the reader. The theoretical study may also be helpful in fitting the experimentally obtained glow curves and, therefore, the elimination of unwanted non-radiation-induced contributions, such as dark current, electronic spikes, light leakage and triboluminescence that generally distort the glow curve shape, can be achieved. PMID:15843392

  8. Luminescence-based retrospective dosimetry using Al2O3 from mobile phones: a simulation approach to determine the effects of position.

    PubMed

    Eakins, J S; Kouroukla, E

    2015-06-01

    Monte Carlo modelling has been performed in support of efforts to establish emergency dosimetry services based on optically or thermally stimulated luminescence (OSL/TL) of the Al(2)O(3) substrate present on the resistors found in mobile phones, which can act as fortuitous retrospective dosemeters for photon exposures. Specifically, a range of exposure conditions has been modelled to assess the dependence of the dosimetry on factors such as the position of resistors within a phone, the orientation of the phone relative to the source, and the location of the phone relative to its owner. Variations due to the resistors' positions and the phone's orientation were generally found to contribute just a few percent to the uncertainty on the dose assessments, though the electrical contacts surrounding the resistors could potentially enhance these by several 10s of percent. But, the location of the phone was found to impact dosimetry greatly. The largest discrepancies in the results were found for low-energy exposures: for (192)Ir, differences of up to an order-of-magnitude were found between resistor and whole body doses. The outcome of the work was to derive correction / calibration factors that can be applied to estimate whole body doses from OSL/TL readings, the accurate application of which would depend on the knowledge of the exposure geometry and the degree of conservatism acceptable for the dose assessment. PMID:25884152

  9. The effective dose of different scanning protocols using the Sirona GALILEOS® comfort CBCT scanner

    PubMed Central

    Bohay, R; Kaci, L; Barnett, R; Battista, J

    2015-01-01

    Objectives: To determine the effective dose and CT dose index (CTDI) for a range of imaging protocols using the Sirona GALILEOS® Comfort CBCT scanner (Sirona Dental Systems GmbH, Bensheim, Germany). Methods: Calibrated optically stimulated luminescence dosemeters were placed at 26 sites in the head and neck of a modified RANDO® phantom (The Phantom Laboratory, Greenwich, NY). Effective dose was calculated for 12 different scanning protocols. CTDI measurements were also performed to determine the dose–length product (DLP) and the ratio of effective dose to DLP for each scanning protocol. Results: The effective dose for a full maxillomandibular scan at 42 mAs was 102 ± 1 μSv and remained unchanged with varying contrast and resolution settings. This compares with 71 μSv for a maxillary scan and 76 μSv for a mandibular scan with identical milliampere-seconds (mAs) at high contrast and resolution settings. Conclusions: Changes to mAs and beam collimation have a significant influence on effective dose. Effective dose and DLP vary linearly with mAs. A collimated maxillary or mandibular scan decreases effective dose by approximately 29% and 24%, respectively, as compared with a full maxillomandibular scan. Changes to contrast and resolution settings have little influence on effective dose. This study provides data for setting individualized patient exposure protocols to minimize patient dose from ionizing radiation used for diagnostic or treatment planning tasks in dentistry. PMID:25358865

  10. Establishment of trigger levels to steer the follow-up of radiation effects in patients undergoing fluoroscopically-guided interventional procedures in Belgium.

    PubMed

    Struelens, L; Bacher, K; Bosmans, H; Bleeser, F; Hoornaert, M T; Malchair, F; Balter, S

    2014-12-01

    The accumulated dose to the skin of the patient during fluoroscopically-guided procedures can exceed the thresholds for tissue reactions. In practice, interventionalists have no direct information about the local procedure-related skin doses in their patient, causing suboptimal or delayed treatment. In current study, the accumulated Kerma-Area-Product (KAP) values were registered, as well as the reference air kerma (Ka,r) values, if available, for almost 200 cases undergoing seven different procedures. A sheet filled with 50 thermoluminescent dosemeters was wrapped around each patient to measure the peak skin dose. In a significant part of the Transjugular Intrahepatic Portosystemic Shunt (TIPSS) procedures, chemo-embolizations of the liver and cerebral embolizations, the threshold values for deterministic skin damage (2 Gy) were attained. Trigger values in terms of KAP, corresponding to a peak skin dose of 2 Gy, were determined. In general, our results comply reasonably well with the values proposed in the NCRP 168 report, with a KAP value of 425 Gy cm² and a Ka,r value of 3 Gy, corresponding to a peak skin dose of 3 Gy. Only for the TIPSS procedure a considerably lower value of 2 Gy was obtained at the published Ka,r and for the RF ablations we obtained a considerably lower value of 250 Gy cm² in terms of KAP. PMID:25277316

  11. The effects of high ambient radon on thermoluminescence dosimetry readings.

    PubMed

    Harvey, John A; Kearfott, Kimberlee J

    2011-11-01

    The effect of a high level of ambient (222)Rn gas on thermoluminescence dosemeters (TLDs) is examined. Groups of LiF:Mg,Ti and CaF(2):Dy TLDs were exposed to (222)Rn under controlled environmental conditions over ∼7 d using a luminous (226)Ra aircraft dial. LiF:Mg,Ti TLDs were tested bare, and both types were tested mounted in cards used for environmental dosimetry and mounted in cards enclosed in plastic badges. A passive continuous radon monitor was used to measure the (222)Rn level in the small chamber during the experiments. The data were analysed to determine the relationship between the integrated (222)Rn level and the TLD response. Although both LiF:Mg,Ti and CaF(2):Dy TLDs showed a strong response to (222)Rn, the badges prevented measurable radon detection by the TLDs within. The TLDs were not used to directly measure the radon concentration; rather, a correction for its influence was desired. PMID:21177272

  12. Three-dimensional radiation dose measurements with Ferrous Benzoic Acid Xylenol Orange in Gelatin gel and optical absorption tomography

    NASA Astrophysics Data System (ADS)

    Bero, M. A.; Gilboy, W. B.; Glover, P. M.; Keddie, J. L.

    1999-02-01

    The optical characteristics of a Ferrous Benzoic Acid Xylenol Orange in Gelatin (FBXG) gel have been studied over the wavelength range 300-700 nm as a function of radiation dose. The unirradiated gel exhibits a strong absorption peak at 440 nm; with increasing dose this peak starts to reduce in intensity while a new broad peak centred at 585 nm begins to appear. Using 60Co gamma rays the absorption coefficients for these two peaks were found to vary linearly with dose up to at least 30 Gy with slopes of -0.028 cm-1 Gy-1 (440 nm) and 0.069 cm-1 Gy-1 (585 nm). The pre- and post-irradiation stability was studied and absorbance changes of less than 1% per hour were observed over periods of a few days. The NMR response of FBXG gels was found to be marginally reduced compared to the standard Fricke dosemeter in gel form and the NMR technique is much less sensitive than the optical readout method. Tissue equivalent phantoms with dimensions of several centimetres can be constructed of FBXG gel and Optical Absorption Tomography (OAT) used to measure the three-dimensional dose distribution within them after exposure to radiation beams. The OAT technique is a much simpler and cheaper method of readout compared with Magnetic Resonance Imaging (MRI).

  13. Preliminary indoor thoron measurements in high radiation background area of southeastern coastal Orissa, India.

    PubMed

    Ramola, R C; Prasad, G; Gusain, G S; Rautela, B S; Choubey, V M; Sagar, D Vidya; Tokonami, S; Sorimachi, A; Sahoo, S K; Janik, M; Ishikawa, T

    2010-10-01

    This paper presents the preliminary results of radon and thoron measurements in the houses of Chhatrapur area of southeastern coast of Orissa, India. This area is one of the high radiation background radiation areas in India, which consists of monazite sand as the source of thoron. Both active and passive methods were employed for the measurements. Radon and thoron concentrations were measured in the houses of Chhatrapur area using twin cup radon dosemeters, RAD7 and radon-thoron discriminative detector (Raduet). Thoron progeny concentration was also measured in the houses using deposition rate measurements. Radon and thoron concentrations in the houses of study area were found to vary from 8 to 47 Bq m(-3) and the below detection level to 77 Bq m(-3), respectively. While thoron progeny concentration in these houses ranges between 0.17 and 4.24 Bq m(-3), preliminary investigation shows that the thoron concentration is higher than radon concentration in the houses of the study area. The thoron progeny concentration was found to be comparatively higher, which forms a base for further study in the area. The comparison between the results of various techniques is presented in this paper. PMID:20833682

  14. Radiation exposure in interventional radiology

    NASA Astrophysics Data System (ADS)

    Pinto, N. G. V.; Braz, D.; Vallim, M. A.; Filho, L. G. P.; Azevedo, F. S.; Barroso, R. C.; Lopes, R. T.

    2007-09-01

    The aim of this study is to evaluate dose values in patients and staff involved in some interventional radiology procedures. Doses have been measured using thermoluminescent dosemeters for single procedures (such as renal and cerebral arteriography, transjungular intrahepatic portasystemic shunt (TIPS) and chemoembolization). The magnitude of doses through the hands of interventional radiologists has been studied. Dose levels were evaluated in three points for patients (eye, thyroid and gonads). The dose-area product (DAP) was also investigated using a Diamentor (PTW-M2). The dose in extremities was estimated for a professional who generally performed one TIPS, two chemoembolizations, two cerebral arteriographies and two renal arteriographies in a week. The estimated annual radiation dose was converted to effective dose as suggested by the 453-MS/Brazil norm The annual dose values were 137.25 mSv for doctors, 40.27 mSv for nurses and 51.95 mSv for auxiliary doctors, and all these annual dose values are below the limit established. The maximum values of the dose obtained for patients were 6.91, 10.92 and 15.34 mGy close to eye, thyroid and gonads, respectively. The DAP values were evaluated for patients in the same interventional radiology procedures. The dose and DAP values obtained are in agreement with values encountered in the literature.

  15. The dependence of skin lesions on the depth-dose distribution from beta-irradiation of people in the Chernobyl nuclear power plant accident.

    PubMed

    Barabanova, A; Osanov, D P

    1990-04-01

    A detailed study was made of the conditions of exposure of 56 victims of the Chernobyl accident who suffered radiation lesions in the skin. The most typical conditions were experimentally reconstructed in order to investigate the specific characteristics of the distribution of doses to the skin according to depth for different exposure conditions. The absorbed doses at depths of 7 mg cm-2 and 150 mg cm-2 were calculated on the basis of measurements with multilayer skin dosemeters. The patients were classified into four groups. Dosimetric characteristics for each group were compared with the clinical pictures to establish the critical factors in the occurrence of lesions. It was demonstrated that the depth-dose distribution of beta-radiation to the skin is of great influence not only for the early effects of radiation but also for the later effects. Radiation lesions in the skin led to death if the area of the lesions exceeded about 50% of the total body surface, and if the doses to the skin were about 200-300 Gy at 7 mg cm-2 and more than about 30 Gy at 150 mg cm-2. PMID:1969906

  16. Estimation of organ doses and effective doses in image-guided respiration-gated radiotherapy.

    PubMed

    Nakao, Minoru; Obara, Satoshi; Nabatame, Kuniaki; Akahane, Keiichi; Sanada, Shigeru; Shirai, Toshiyuki

    2016-01-01

    Dose conformity in thoracic and abdominal ion-beam radiotherapy is degraded by respiratory motion. To improve conformity, an image-guided respiration-gated system can be used in the treatment room. The purpose of this study was to estimate the organ doses and effective doses to patients from an image-guided respiration-gated system. Glass dosemeters were inserted into an adult anthropomorphic phantom and were attached to the surface on the phantom. The phantom was placed on the treatment couch, and the imaging dose from fluoroscopy was evaluated. In addition to the organ doses, the effective doses were also estimated according to the ICRP Publication 103. The irradiation time is over 3-5 min per beam angle. When image acquisition conditions were assumed for thoracic treatment, the effective doses and maximal skin doses were 0.48-0.79 mSv and 5.9-9.9 mGy, respectively. The estimated doses can be the base data for considering radiological protection in the radiotherapy. PMID:25848094

  17. Non-vascular interventional procedures: effective dose to patient and equivalent dose to abdominal organs by means of DICOM images and Monte Carlo simulation.

    PubMed

    Longo, Mariaconcetta; Marchioni, Chiara; Insero, Teresa; Donnarumma, Raffaella; D'Adamo, Alessandro; Lucatelli, Pierleone; Fanelli, Fabrizio; Salvatori, Filippo Maria; Cannavale, Alessandro; Di Castro, Elisabetta

    2016-03-01

    This study evaluates X-ray exposure in patient undergoing abdominal extra-vascular interventional procedures by means of Digital Imaging and COmmunications in Medicine (DICOM) image headers and Monte Carlo simulation. The main aim was to assess the effective and equivalent doses, under the hypothesis of their correlation with the dose area product (DAP) measured during each examination. This allows to collect dosimetric information about each patient and to evaluate associated risks without resorting to in vivo dosimetry. The dose calculation was performed in 79 procedures through the Monte Carlo simulator PCXMC (A PC-based Monte Carlo program for calculating patient doses in medical X-ray examinations), by using the real geometrical and dosimetric irradiation conditions, automatically extracted from DICOM headers. The DAP measurements were also validated by using thermoluminescent dosemeters on an anthropomorphic phantom. The expected linear correlation between effective doses and DAP was confirmed with an R(2) of 0.974. Moreover, in order to easily calculate patient doses, conversion coefficients that relate equivalent doses to measurable quantities, such as DAP, were obtained. PMID:26211013

  18. A national dosimetry audit of intraoperative radiotherapy

    PubMed Central

    Earner, B; Faulkner, P; Dancer, N

    2013-01-01

    Objective: National dosimetry audits are a fundamental part of quality assurance in radiotherapy, especially for new techniques. Intraoperative radiotherapy with a compact mobile kilovoltage X-ray source is a novel approach for the treatment of breast and other cancers. All seven current clinical sites in the UK were audited by a single visiting group and set of measurement equipment. Methods: Measurements of output, isotropy and depth doses were performed using an ion chamber in solid water, thermoluminescent dosemeters and radiochromic film, respectively. Results: The mean difference between measured and planned dose across all centres was ?3.22.7%. Measured isotropy was within 3% around the lateral plane of the X-ray source and +114% in the forward direction compared with the lateral plane. Measured depth doses were agreed within 52% of manufacturer-provided calibration values or a mean gamma index of 97% at a tolerance of 7%/0.5?mm. Conclusion: Agreement within measurement uncertainties was found for all three parameters except forward anisotropy, which is unlikely to be clinically significant. Steep dose gradients increase the sensitivity to small variations in positioning, but these tests are practical for use in interdepartmental audits and local baseline comparison. Advances in knowledge: The first UK interdepartmental audit of intraoperative radiotherapy builds confidence in the delivery of this treatment. PMID:24133058

  19. Comparison between direct measurements and modeled estimates of external radiation exposure among school children 18 to 30 months after the Fukushima nuclear accident in Japan.

    PubMed

    Nomura, Shuhei; Tsubokura, Masaharu; Hayano, Ryugo; Furutani, Tomoyuki; Yoneoka, Daisuke; Kami, Masahiro; Kanazawa, Yukio; Oikawa, Tomoyoshi

    2015-01-20

    After a major radioactive incident, accurate dose reconstruction is important for evaluating health risks and appropriate radiation protection policies. After the 2011 Japan Fukushima nuclear incident, we assessed the level of agreement between the modeled and directly measured dose and estimated the uncertainties. The study population comprised 520 school children from Minamisoma city, located 20 km north of the nuclear plant. The annual dose 1830 months after the incident was assessed using two approaches: estimation using the model proposed by the Japanese government and direct measurement by radiation dosemeters. The ratio of the average of modeled and measured doses was 3.0 (standard deviation (SD): 2.0). The reduction coefficient, an index for radiation attenuation properties, was 0.3 (SD: 0.1) on average, whereas the value used in the government model was 0.6. After adjusting for covariates, the coefficient had a significant negative correlation with the air dose rate in the dwelling location (p < 0.001), indicating that stronger building shielding effects are valuable in areas with higher air contamination levels. The present study demonstrated that some overestimation may have been related to uncertainties in radiation reduction effects, and that the air contamination level might provide a more important indicator of these effects. PMID:25514624

  20. 41Ca - a possible neutron specific biomarker in tooth enamel

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Arazi, A.; Faestermann, T.; Knie, K.; Korschinek, G.; Maier, H. J.; Nakamura, N.; Rhm, W.; Rugel, G.

    2004-08-01

    The measurement of long-lived radionuclides, produced by neutrons originating from the atomic-bomb explosions, offers the possibility to reconstruct neutron fluences to which survivors in Hiroshima and Nagasaki were exposed. The long-lived radionuclide, 41Ca (T1/2=103 000 years), is suggested here as a means for a retrospective determination of thermal neutron fluences, directly within the human body of a survivor. As proper material tooth enamel is proposed. The 41Ca signal in tooth enamel may be correlated with the exposure to A-bomb induced thermal neutron fluences, provided the natural background level of 41Ca/Ca is significantly lower. Therefore, tooth samples of unexposed survivors of the A-bomb explosions have been examined by means of accelerator mass spectrometry, in order to quantify the natural background level of 41Ca/Ca. Measured 41Ca/Ca ratios were confirmed to be as low as about 2 10-15. Thus, the A-bomb induced additional signal should be detectable for survivors at epidemiological relevant distances. Since tooth enamel had already been used as a dosemeter for gamma radiation from the A-bomb explosion, the detection of 41Ca in tooth enamel would allow, for the first time, an assessment of both, ?-ray and neutron exposures in the same biological material.

  1. The role of shielding in superficial X-ray therapy.

    PubMed

    Medvedevas, N; Adliene, D; Laurikaitiene, J; Andrejaitis, A

    2011-09-01

    Superficial X-ray therapy is applicable in the kilovoltage range for the treatment of the cancer. Pb shielding is used to protect radiation-sensitive organs since the doses are high, however the question about shielding efficiency is still open. The role of shielding was investigated in this work based on the results of dose measurements performed using a set of pencil dosemeters and thermoluminescent dosimetries. According to the measured angular dose distributions on the phantom surface during X-ray irradiation, the area near the applicator exposed to the waste irradiation was evaluated and Pb shielding of a corresponding size was chosen. It has been shown that the dose in the area of interest decreases non-linearly, however high shielding efficiency (~90 %) remains almost stable in the whole area. No significant contribution of secondary scattered photons from Pb has been observed. The role of Pb shielding in superficial X-ray therapy is discussed on the basis of the obtained results. PMID:21816725

  2. Personal dose equivalent conversion coefficients for electrons to 1 Ge V.

    PubMed

    Veinot, K G; Hertel, N E

    2012-04-01

    In a previous paper, conversion coefficients for the personal dose equivalent, H(p)(d), for photons were reported. This note reports values for electrons calculated using similar techniques. The personal dose equivalent is the quantity used to approximate the protection quantity effective dose when performing personal dosemeter calibrations and in practice the personal dose equivalent is determined using a 303015 cm slab-type phantom. Conversion coefficients to 1 GeV have been calculated for H(p)(10), H(p)(3) and H(p)(0.07) in the recommended slab phantom. Although the conversion coefficients were determined for discrete incident energies, analytical fits of the conversion coefficients over the energy range are provided using a similar formulation as in the photon results previously reported. The conversion coefficients for the personal dose equivalent are compared with the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection guidance. Effects of eyewear on H(p)(3) are also discussed. PMID:21715410

  3. Strict X-ray beam collimation for facial bones examination can increase lens exposure

    PubMed Central

    Powys, R; Robinson, J; Kench, P L; Ryan, J; Brennan, P C

    2012-01-01

    Objectives It is well accepted that collimation is a cost-effective dose-reducing tool for X-ray examinations. This phantom-based study investigated the impact of X-ray beam collimation on radiation dose to the lenses of the eyes and thyroid along with the effect on image quality in facial bone radiography. Methods A three-view series (occipitomental, occipitomental 30 and lateral) was investigated, and radiation doses to the lenses and thyroid were measured using an Unfors dosemeter. Images were assessed by six experienced observers using a visual grading analysis and a total of 5400 observations were made. Results Strict collimation significantly (p<0.0001) reduced the radiation dose to the lenses of the eyes and thyroid when using a fixed projection-specific exposure. With a variable exposure technique (fixed exit dose, to simulate the behaviour of an automatic exposure control), while strict collimation was again shown to reduce thyroid dose, higher lens doses were demonstrated when compared with larger fields of exposure. Image quality was found to significantly improve using strict collimation, with observer preference being demonstrated using visual grading characteristic curves. Conclusion The complexities of optimising radiographic techniques have been shown and the data presented emphasise the importance of examining dose-reducing strategies in a comprehensive way. PMID:22374279

  4. The MATROSHKA Experiment - First Mission Results

    NASA Astrophysics Data System (ADS)

    Reitz, Guenther

    MATROSHKA is an ESA multi-user experiment unit on the International Space Station ISS for studies of depth dose distribution of the different components of the orbital radiation field at different sites of the organs, occurring in astronauts being exposed during an EVA. To accomplish that, the facility comprises an anthropomorphic phantom to simulate the human body, active and passive detectors for space radiation dosimetry, data acquisition and processing electronics and the overall mechanical housing and support structure for the MATROSHKA components. The development and manufacture was under ESA contract by DLR, Institute for Aerospace Medicine with sub-contractors Kayser Italia (Livorno) and DTM (Modena). MATROSHKA was launched within PROGRESS on January 29, 2004 and mounted shortly afterwards outside the Russian Zvezda Module of the Station. The time of outside exposure during this mission phase was 539 days. After that, the facility was returned into the Station for passive sensor exchange. After the first passive detector set was returned to ground with Soyuz for on-ground evaluation the facility is further used inside the station during two follow-on project phases. The MATROSHKA experiment delivered a unique set of data results from the evaluation of numerous detectors, such as Thermoluminescence detectors, plastic nuclear track detectors and silicon dosemeters. This paper intends to give besides a short overview of the instrumentation used inside the MATROSHKA facility selected results from the first exposure and describes the determination of organ dose equivalents from these results

  5. Comparison of radiation doses between newborns and 6-y-old children undergoing head, chest and abdominal CT examinations: a phantom study.

    PubMed

    Sugimoto, Naruto; Aoyama, Takahiko; Koyama, Shuji; Yamauchi-Kawaura, Chiyo; Fujii, Keisuke

    2013-01-01

    Radiation doses in paediatric computed tomography (CT) were investigated for various types of recent CT scanners with newborn and 6-y-old phantoms in which silicon-photodiode dosemeters were implanted at various organ positions. In the head, chest and abdominal CT for the newborn phantom, doses for organs within the scan region were 21-40, 3-8 and 3-12 mGy, respectively. The corresponding doses for the child phantom were 20-37, 2-11 and 4-17 mGy, respectively. In the head, chest and abdominal CT, the effective doses were respectively 2.1-3.3, 2.0-6.0 and 2.2-10.0 mSv for the newborn, and 1.0-2.0, 1.2-6.6 and 2.9-11.8 mSv for the child. Radiation doses for the newborn were at the same levels as those for the child, excepting effective doses in head CT for the newborn, which were 1.8 times higher than those for the child. PMID:22645383

  6. Comparison between the effects of inhaled isoprenaline and fenoterol on plasma cyclic AMP and heart rate in normal subjects.

    PubMed Central

    Fairfax, A J; Rehahn, M; Jones, D; O'Malley, B

    1984-01-01

    The time course of changes in plasma cyclic AMP, heart rate and bronchial tone after inhalation of fenoterol or isoprenaline from a dose-metered aerosol are reported in a group of normal subjects. After isoprenaline, plasma cyclic AMP increased rapidly reaching a peak by 10 min and returned to basal levels within 60 min. A rapid, transient rise in heart rate occurred that was maximal by 5 min and returned to a basal level by 45 min. After fenoterol, the changes in cyclic AMP and heart rate were of much longer duration. The rise in plasma cyclic AMP was slower in onset and of greater magnitude than for isoprenaline, reaching a peak by 20 min and remaining above basal level for more than 6 h. The maximum increase in heart rate after fenoterol was less than that observed with isoprenaline but an elevated rate persisted for 4 h after inhalation of fenoterol. Fenoterol is known to have a longer duration of action as a bronchodilator in comparison with isoprenaline. The prolonged rise in plasma cyclic AMP in normal subjects given inhaled fenoterol may reflect this long duration of action. The concomitant rise in heart rate, however, suggests that the duration of plasma cyclic AMP response may in part be due to the systemic effect of the fraction of inhaled fenoterol known to be absorbed via the buccal and intestinal routes. PMID:6322828

  7. Estimation of the risk of secondary cancer in the thyroid gland and the breast outside the treated volume in patients undergoing brain, mediastinum and breast radiotherapy.

    PubMed

    Vlachopoulou, Vassiliki; Malatara, Georgia; Delis, Harry; Kardamakis, Dimitrios; Panayiotakis, George

    2013-04-01

    The purpose of this study was to measure the peripheral dose which is the absorbed dose in organs located outside the treatment volume such as the thyroid gland and the breast in patients undergoing radiotherapy, utilising the MOSFET dosemeters, as well as to estimate the probability of secondary cancer. The thyroid gland doses, expressed as a percentage of the prescribed dose (%TD), were measured to be 2.0±0.3 %, in whole brain irradiation, 10.0±8.0 % in mediastinum treatment and 8.0±2.0 and 2.0±0.8 % in breast treatment, with and without the supraclavicular irradiation, respectively, with a corresponding risk of 0.2, 2.0, 1.0 and 0.3 %. The dose to the breast was 7.0±2.0 %, in the mediastinum treatment, and 4.0±1.0 and 2.0±0.8 %, in the breast treatment, with and without supraclavicular irradiation, respectively, with a corresponding risk of 4.0, 2.0 and 1.0 %. Although the results indicate that the risk is not negligible, its significance should be considered in conjunction with the existing pathology and age of the patients. PMID:22923288

  8. Comparison of measured and calculated spatial dose distributions for a bench-mark 106Ru/106Rh hot particle source.

    PubMed

    Aydarous, A Sh; Charles, M W; Darley, P J

    2008-01-01

    This study is a part of a programme of research to provide validated dose measurement and calculation techniques for beta emitting hot particles by the construction of well-defined model hot particle sources. This enables parallel measurements and calculations to be critically compared. This particular study concentrates on the high-energy beta emitter, (106)Ru/(106)Rh (Emax = 3.54 MeV). This source is a common constituent of failed nuclear fuel, particularly in accident situations. The depth dose distributions were measured using radiochromic dye film (RDF); an imaging photon detector coupled to an LiF thermoluminescent dosemeter (LiF-IPD) and an extrapolation ionisation chamber (ECH). Dose calculations were performed using the Monte Carlo radiation transport code MCNP4C. Doses were measured and calculated as average values over various areas and depths. Of particular interest are the doses at depths of 7 and 30-50 mg cm(-2), and averaged over an area of 1 cm2, as recommended by the International Commission on Radiological Protection for use in routine and accidental over-exposures of the skin. In this case, the average ratios (MCNP/measurement) for RDF, ECH and LiF-IPD were 1.07 +/- 0.02, 1.02 +/- 0.01 and 0.83 +/- 0.16, respectively. There are significantly greater discrepancies between the ECH and LiF-IPD measurement techniques and calculations-particularly for shallow depths and small averaging areas. PMID:18083995

  9. Samarium-153 therapy for prostate cancer: the evaluation of urine activity, staff exposure and dose rate from patients.

    PubMed

    Parlak, Yasemin; Gumuser, Gul; Sayit, Elvan

    2015-03-01

    The aim of this study was to determine the excretion of Samarium-153-ethylenediaminetetramethylphosphonic acid ((153)Sm-EDTMP) in urine and to calculate the dose rate of its retention in the body as a function of time and the dose received by the skin of laboratory staff's finger. Urine samples were collected from 11 patients after intravenous injection of (153)Sm-EDTMP. The measurements of dose rate were performed. Thermoluminescent dosemeters were used for absorbed dose measurements. Effective half-lives that were calculated from urine sample measurements were found as 7.13 h within the first 24 h. Whole body dose rates before collecting urine of patients were 60.0 15.7 Sv h(-1) for within 1 h following (153)Sm-EDTMP administration. The highest finger radiation dose is to the right-hand thumb (3.8 2 mGy). The results of the study imply that patients who recieved (153)Sm-EDTMP therapy should be kept a minumum of 8 h in an isolated room at hospital and that one staff should give therapy at most two patients per week. PMID:25063786

  10. The effective dose assessment of C-arm CT in hepatic arterial embolisation therapy

    PubMed Central

    Tyan, Y-S; Li, Y-Y; Ku, M-C; Huang, H-H

    2013-01-01

    Objective: To assess the effective dose of the liver C-arm computed tomography (CT) scan during hepatic arterial embolisation surgery with clinical dose–area product (DAP) data from Taiwan. Methods: The experiment used two kinds of phantoms: RANDO® Man and RANDO Woman (The Phantom Laboratory, Salem, NY), embedded with thermoluminescent dosemeters at locations according to the International Commission on Radiological Protection 103 report. The conversion factors of DAP to effective doses for males and females, respectively, were obtained. The clinical DAP data of liver C-arm CT scan during hepatic arterial embolisation surgery were collected in a hospital in Taiwan. Results: There were 125 liver transarterial embolisation therapy cases, including 94 males and 31 females, from February 2009 to June 2010. C-arm CT was used 38 times for males and 17 times for females. The corresponding average and standard deviation of clinical DAP were 61.0±6.6 Gy cm2 and 52.2±8.3 Gy cm2, respectively. Conclusion: The DAP of RANDO Man and RANDO Woman phantoms simply scanned by C-arm CT are much lower than that of patients. After consideration of the clinical DAP of patients, the effective doses of a liver C-arm CT scan recommended for males and females in Taiwan are 11.5±2.3 mSv and 11.3±3.0 mSv, respectively. Advances in knowledge: The conversion factors of DAP to effective doses for males and females are 0.19±0.03 mSv Gy−1 cm−2 and 0.22±0.05 mSv Gy−1 cm−2. Only if the actual DAP value of a patient scan is multiplied by the conversion factor can the correct effective dose be determined. PMID:23403454

  11. The effect of 6 and 15 MV on intensity-modulated radiation therapy prostate cancer treatment: plan evaluation, tumour control probability and normal tissue complication probability analysis, and the theoretical risk of secondary induced malignancies

    PubMed Central

    Hussein, M; Aldridge, S; Guerrero Urbano, T; Nisbet, A

    2012-01-01

    Objective The aim of this study was to investigate the effect of 6 and 15-MV photon energies on intensity-modulated radiation therapy (IMRT) prostate cancer treatment plan outcome and to compare the theoretical risks of secondary induced malignancies. Methods Separate prostate cancer IMRT plans were prepared for 6 and 15-MV beams. Organ-equivalent doses were obtained through thermoluminescent dosemeter measurements in an anthropomorphic Aldersen radiation therapy human phantom. The neutron dose contribution at 15 MV was measured using polyallyl-diglycol-carbonate neutron track etch detectors. Risk coefficients from the International Commission on Radiological Protection Report 103 were used to compare the risk of fatal secondary induced malignancies in out-of-field organs and tissues for 6 and 15 MV. For the bladder and the rectum, a comparative evaluation of the risk using three separate models was carried out. Dose–volume parameters for the rectum, bladder and prostate planning target volume were evaluated, as well as normal tissue complication probability (NTCP) and tumour control probability calculations. Results There is a small increased theoretical risk of developing a fatal cancer from 6 MV compared with 15 MV, taking into account all the organs. Dose–volume parameters for the rectum and bladder show that 15 MV results in better volume sparing in the regions below 70 Gy, but the volume exposed increases slightly beyond this in comparison with 6 MV, resulting in a higher NTCP for the rectum of 3.6% vs 3.0% (p=0.166). Conclusion The choice to treat using IMRT at 15 MV should not be excluded, but should be based on risk vs benefit while considering the age and life expectancy of the patient together with the relative risk of radiation-induced cancer and NTCPs. PMID:22010028

  12. A single plan solution to chest wall radiotherapy with bolus?

    PubMed Central

    Ordonez-Sanz, C; Bowles, S; Hirst, A

    2014-01-01

    Objective: Radiotherapy treatments of post-mastectomy chest walls are complex, requiring treatment close to skin, necessitating bolus use. Commonly used 5- and 10-mm-thick boluses develop full skin dose, needing removal for the latter half of treatment and requiring two treatment plans to be generated. Can a thinner bolus be used for all treatment fractions, requiring only one plan? Methods: Investigation of doses received using (A) a half-time 10-mm-thick Vaseline® bolus (current situation); (B) a brass mesh (Whiting & Davis, Attleboro Falls, MA) and (C) 3- and 5-mm Superflab™ (Mick Radio-Nuclear Instruments, Mount Vernon, NY) for 6 and 15 MV. Dosimetric measurements in Barts WT1 solid water and an anthropomorphic phantom, using ionization chambers and thermoluminescent dosemeters, were used to study the effect of different bolus regimes on the photon depth–dose curves (DDCs) and skin doses. Results: Measured skin doses for the current 10-mm-thick Vaseline bolus, brass mesh and 3-mm bolus were compared (5 mm bolus has been rejected). The brass mesh has the least effect on the DDC, with changes <0.7% for depths greater than dmax. Brass mesh conforms superiorly to skin surfaces. Measurements on an anthropomorphic phantom demonstrate an increased skin dose compared with our current treatment protocol. Conclusion: Brass mesh has the smallest effect on the DDC, whilst sufficiently increasing surface dose. It can be removed at any fraction, based on a clinical decision, without the need for generating a new plan. Treating with one plan significantly reduces planning times. Advances in knowledge: Quantification of skin doses required and achieved from wax-on/wax-off treatment compared with alternative available breast boluses. PMID:24646288

  13. Occupational radiation doses to the extremities and the eyes in interventional radiology and cardiology procedures

    PubMed Central

    Efstathopoulos, E P; Pantos, I; Andreou, M; Gkatzis, A; Carinou, E; Koukorava, C; Kelekis, N L; Brountzos, E

    2011-01-01

    Objectives The aim of this study was to determine occupational dose levels in interventional radiology and cardiology procedures. Methods The study covered a sample of 25 procedures and monitored occupational dose for all laboratory personnel. Each individual wore eight thermoluminescent dosemeters next to the eyes, wrists, fingers and legs during each procedure. Radiation protection shields used in each procedure were recorded. Results The highest doses per procedure were recorded for interventionists at the left wrist (average 485 μSv, maximum 5239 μSv) and left finger (average 324 μSv, maximum 2877 μSv), whereas lower doses were recorded for the legs (average 124 μSv, maximum 1959 μSv) and the eyes (average 64 μSv, maximum 1129 μSv). Doses to the assisting nurses during the intervention were considerably lower; the highest doses were recorded at the wrists (average 26 μSv, maximum 41 μSv) and legs (average 18 μSv, maximum 22 μSv), whereas doses to the eyes were minimal (average 4 μSv, maximum 16 μSv). Occupational doses normalised to kerma area product (KAP) ranged from 11.9 to 117.3 μSv/1000 cGy cm2 and KAP was poorly correlated to the interventionists' extremity doses. Conclusion Calculation of the dose burden for interventionists considering the actual number of procedures performed annually revealed that dose limits for the extremities and the lenses of the eyes were not exceeded. However, there are cases in which high doses have been recorded and this can lead to exceeding the dose limits when bad practices are followed and the radiation protection tools are not properly used. PMID:21172967

  14. Comparison of effective dose and lifetime risk of cancer incidence of CT attenuation correction acquisitions and radiopharmaceutical administration for myocardial perfusion imaging

    PubMed Central

    Szczepura, K; Hogg, P

    2014-01-01

    Objective: To measure the organ dose and calculate effective dose from CT attenuation correction (CTAC) acquisitions from four commonly used gamma camera single photon emission CT/CT systems. Methods: CTAC dosimetry data was collected using thermoluminescent dosemeters on GE Healthcare's Infinia™ Hawkeye™ (GE Healthcare, Buckinghamshire, UK) four- and single-slice systems, Siemens Symbia™ T6 (Siemens Healthcare, Erlangen, Germany) and the Philips Precedence (Philips Healthcare, Amsterdam, Netherlands). Organ and effective dose from the administration of 99mTc-tetrofosmin and 99mTc-sestamibi were calculated using International Commission of Radiological Protection reports 80 and 106. Using these data, the lifetime biological risk was calculated. Results: The Siemens Symbia gave the lowest CTAC dose (1.8 mSv) followed by the GE Infinia Hawkeye single-slice (1.9 mSv), GE Infinia Hawkeye four-slice (2.5 mSv) and Philips Precedence v. 3.0. Doses were significantly lower than the calculated doses from radiopharmaceutical administration (11 and 14 mSv for 99mTc-tetrofosmin and 99mTc-sestamibi, respectively). Overall lifetime biological risks were lower, which suggests that using CTAC data posed minimal risk to the patient. Comparison of data for breast tissue demonstrated a higher risk than that from the radiopharmaceutical administration. Conclusion: CTAC doses were confirmed to be much lower than those from radiopharmaceutical administration. The localized nature of the CTAC exposure compared to the radiopharmaceutical biological distribution indicated dose and risk to the breast to be higher. Advances in knowledge: This research proved that CTAC is a comparatively low-dose acquisition. However, it has been shown that there is increased risk for breast tissue especially in the younger patients. As per legislation, justification is required and CTAC should only be used in situations that demonstrate sufficient net benefit. PMID:24998249

  15. Replacement tissue-equivalent proportional counter for the International Space Station.

    PubMed

    Perez-Nunez, D; Braby, L A

    2011-02-01

    The tissue-equivalent proportional counter (TEPC)-based dosemeters used on the International Space Station have exceeded their planned useful lives, and are scheduled to be replaced with the new units taking advantage of improved technology. The original TEPC detectors used cylindrical geometry with field tubes to achieve good energy resolution and minimum sensitivity to noise created by vibration. The inside diameter of these detectors is 5.1 cm. The new detectors developed for this application produce the resolution and vibration resistance of the cylindrical detector with the isotropic response and compact size of a spherical detector. The cathode structure consists of conductive tissue-equivalent plastic A-150 layers separated by thin polyethylene layers perpendicular to the anode. Each conductive layer is held at the electrical potential needed to produce uniform electric field strength along the anode wire, and thus the same gas gain for electrons produced in different portions of the spherical volume. The new design contains the whole preamplifier inside the vacuum chamber to reduce electronic noise. Also the vacuum chamber has a novel design with a 0.020-inch-thick aluminium wall to allow a total wall thickness of 0.5 g cm(-2), which is typical of the shielding provided by a space suit. This feature will allow measuring the dose on the astronauts' skin due to low-energy electrons and protons produced during solar events. The vacuum chamber has a new bayonet clamping system that reduces the total detector weight to less than half that of the old TEPC. PMID:21115447

  16. Indoor radon/thoron levels and inhalation doses to some populations in Himachal Pradesh, India.

    PubMed

    Virk, H S; Sharma, Navjeet

    2002-02-01

    It is well established that some areas of Himachal Pradesh (H.P.) state of India situated in the environs of the Himalayan mountains are relatively rich in uranium-bearing minerals. Some earlier studies by our group have indicated high levels of radon (>200 Bq m(-3)) in the dwellings. It is in this context that an indoor radon/thoron survey has been carried out in selected villages of four districts in the state of H.P. This survey has been conducted as a part of a national, coordinated project using twin chamber dosemeter cups designed by the Environmental Assessment Division (EAD), Department of Atomic Energy, Govt. of India. The track-etch technique is used for calibration of plastic detector LR-115 type-II which are employed for recording alpha tracks due to radon/thoron and their daughters. Year long radon/thoron data have been collected for seasonal correlations of indoor radon/thoron in the dwellings. The indoor radon levels have been found to vary from a minimum value of 17.4 Bq m(-3) to a maximum value of 140.3 Bq m(-3). The indoor thoron levels vary from a minimum value of 5.2 Bq m(-3) to a maximum value of 131.9 Bq m(-3). The year average dose rate for the local population varies from 0.03 microSv h(-1) to 0.83 microSv h(-1). The annual exposure dose to inhabitants in all the dwellings lies below the upper limit of 10 mSv given in ICRP-65. PMID:11871700

  17. Indoor radon concentration in the rural dwellings of Chhattisgarh state (India).

    PubMed

    Khokhar, M S K; Kher, R S; Rathore, V B; Ramachandran, T V

    2006-01-01

    Inhalation of radon and its daughter products is the major contributor to the total exposure of the population to natural radiation. An indoor radon survey has been carried out in the state of Chhattisgarh (80.26 degrees N to 84.41 degrees N and 17.8 degrees E to 24.1 degrees E), India under the national coordinated radon project of the Department of Atomic Energy. In the frame of this project indoor radon concentration has been measured in 105 dwellings situated in different villages of Chhattisgarh state. Houses were selected for measurements to cover the most common type of houses generally existing in the rural areas. Measurements have been done on quarterly integrating cycle for one full year in each dwelling using radon cup dosemeter employing LR-115, type-II (pelliculable), solid-state nuclear track detectors. The gamma radiation level was also checked in each dwelling using a gamma survey meter. It was found that the annual average indoor radon concentration in these dwellings varies from 9.91 to 87.84 Bq m(-3) with overall mean value of 26.48 Bq m(-3). Gamma level in these rural dwellings varies from 14.84 to 26.56 microR h(-1) with mean value of 18.68 microR h(-1). We observed that the radon concentration is relatively higher in the houses where the floor is bare but relatively lower in those houses where the floor is tiled or cemented. PMID:16645001

  18. Concentrations of radon and its daughter products in and around Bangalore city.

    PubMed

    Ningappa, C; Sannappa, J; Chandrashekara, M S; Paramesh, L

    2008-01-01

    Indoor radon and its progeny levels were measured during 2005-06 in Bangalore rural district and in Bangalore City by using Solid State Nuclear Track Detector (SSNTD)-based twin cup dosemeters, and the activity of radium present in soils and rocks was measured by using HPGe detector. Fifty dwellings of different types were chosen for the measurement. The dosimeters containing the detector (LR-115 Type II Film) used in each house were fixed 2 m above the floor. After an exposure time of 90 days, films were etched to reveal tracks. From the track density, the concentrations of radon were evaluated. The value of radon concentration in the indoor air near granite quarries varies from 55 to 300 Bq.m(-3) with a median of 155 Bq.m(-3) and its progeny varies from 0.24 to 19.6 mWL with a median of 8.4 mWL. In Bangalore City, the concentration of radon varies from 18.4 to 110 Bq.m(-3) with a median of 45 Bq.m(-3) and its progeny varies from 1.62 to 11.24 mWL with a median of 4.15 mWL. Higher concentrations of radon and its progeny were observed in granite quarries compared with Bangalore City. The main reason for the higher indoor radon and its progeny concentration is due to the mining activity and the types of the bedrock. The concentration of radon mainly depends on the activity of radium present in soils and rocks and the types of building materials used. The activity of radium varies in granitic regions of Bangalore rural district from 42.0 to 163.6 Bq.kg(-1) with a median of 112.8 Bq.kg(-1). The concentrations of indoor radon and its daughter products and equivalent effective dose are discussed. PMID:18381336

  19. The reduction of dose in paediatric panoramic radiography: the impact of collimator height and programme selection

    PubMed Central

    Safi, H; Maddison, S M

    2015-01-01

    Objectives: The aim of this work was to estimate the doses to radiosensitive organs in the head of a young child undergoing panoramic radiography and to establish the effectiveness of a short collimator in reducing dose. Methods: Thermoluminescent dosemeters were used in a paediatric head phantom to simulate an examination on a 5-year-old child. The panoramic system used was an Instrumentarium OP200 D (Instrumentarium Dental, Tuusula, Finland). The collimator height options were 110 and 140 mm. Organ doses were measured using exposure programmes intended for use with adult and child size heads. The performance of the automatic exposure control (AEC) system was also assessed. Results: The short collimator reduced the dose to the brain and the eyes by 57% and 41%, respectively. The dose to the submandibular and sublingual glands increased by 32% and 20%, respectively, when using a programme with a narrower focal trough intended for a small jaw. The effective dose measured with the short collimator and paediatric programme was 7.7 μSv. The dose to the lens of the eye was 17 μGy. When used, the AEC system produced some asymmetry in the dose distribution across the head. Conclusions: Panoramic systems when used to frequently image children should have programmes specifically designed for imaging small heads. There should be a shorter collimator available and programmes that deliver a reduced exposure time and allow reduction of tube current. Programme selection should also provide flexibility for focal trough size, shape and position to match the smaller head size. PMID:25352427

  20. Using GafChromic film to estimate the effective dose from dental cone beam CT and panoramic radiography

    PubMed Central

    Al-Okshi, A; Nilsson, M; Petersson, A; Wiese, M; Lindh, C

    2013-01-01

    Objectives: To demonstrate the feasibility of GafChromic® XR-QA2 (ISP Corp., Wayne, NJ) as a dosemeter when performing measurements of the effective dose from three cone beam CT (CBCT) units and to compare the doses from examinations of three common dental clinical situations. A second aim was to compare the radiation doses for three digital panoramic units with the doses for the CBCT units. Methods: The CBCT units used were Veraviewepocs 3De® (J Morita MFG Corp., Kyoto, Japan), ProMax® 3D (Planmeca, Helsinki, Finland) and NewTom VGi® (Quantitative Radiology, Verona, Italy). GafChromic XR-QA2 films were placed between the selected layers of the head and neck of a tissue-equivalent human skull (RANDO® phantom; The Phantom Laboratory, Salem, NY). The exposure parameters were set using the automatic exposure control function of the units. Depending on the availability, medium and smaller field of view (FOV) scanning modes were used. The effective dose was estimated using the 2007 International Commission on Radiological Protection formalism. Results: The lowest effective dose of a CBCT unit was observed for ProMax 3D, FOV 4 × 5 cm (10 μSv), the highest for NewTom VGi, FOV 8 × 8 cm—high resolution (129 μSv). The range of effective doses for digital panoramic machines measured was 8–14 μSv. Conclusions: This study demonstrates the feasibility of using radiochromic films for dental CBCT and panoramic dosimetry. PMID:23610090

  1. Peripheral photon and neutron doses from prostate cancer external beam irradiation.

    PubMed

    Bezak, Eva; Takam, Rundgham; Marcu, Loredana G

    2015-12-01

    Peripheral photon and neutron doses from external beam radiotherapy (EBRT) are associated with increased risk of carcinogenesis in the out-of-field organs; thus, dose estimations of secondary radiation are imperative. Peripheral photon and neutron doses from EBRT of prostate carcinoma were measured in Rando phantom. (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P glass-rod thermoluminescence dosemeters (TLDs) were inserted in slices of a Rando phantom followed by exposure to 80 Gy with 18-MV photon four-field 3D-CRT technique. The TLDs were calibrated using 6- and 18-MV X-ray beam. Neutron dose equivalents measured with CR-39 etch-track detectors were used to derive readout-to-neutron dose conversion factor for (6)LiF:Mg,Cu,P TLDs. Average neutron dose equivalents per 1 Gy of isocentre dose were 3.80.9 mSv Gy(-1) for thyroid and 7.05.4 mSv Gy(-1) for colon. For photons, the average dose equivalents per 1 Gy of isocentre dose were 0.20.1 mSv Gy(-1) for thyroid and 8.19.7 mSv Gy(-1) for colon. Paired (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P TLDs can be used to measure photon and neutron doses simultaneously. Organs in close proximity to target received larger doses from photons than those from neutrons whereas distally located organs received higher neutron versus photon dose. PMID:25564673

  2. Development of an applicator for eye lens dosimetry during radiotherapy

    PubMed Central

    Park, J M; Lee, J; Ye, S-J

    2014-01-01

    Objective: To develop an applicator for in vivo measurements of lens dose during radiotherapy. Methods: A contact lens-shaped applicator made of acrylic was developed for in vivo measurements of lens dose. This lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistors (MOSFETs) dosemeters. CT images of an anthropomorphic phantom with and without the applicator were acquired. Ten volumetric modulated arc therapy plans each for the brain and the head and neck cancer were generated and delivered to an anthropomorphic phantom. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. Results: The average difference between the measured and the calculated doses with the applicator was 3.1??1.8?cGy with a micro MOSFET and 2.8??1.3?cGy with a standard MOSFET. The average difference without the lens applicator was 4.8??5.2?cGy with the micro MOSFET and 5.7??6.5?cGy with the standard MOSFET. The maximum difference with the micro MOSFET was 10.5?cGy with the applicator and 21.1?cGy without the applicator. For the standard MOSFET, it was 6.8?cGy with the applicator and 27.6?cGy without the applicator. Conclusion: The lens applicator allowed reduction of the differences between the calculated and the measured doses during in vivo measurement for the lens compared with in vivo measurement at the surface of the eyelid. Advances in knowledge: By using an applicator for in vivo dosimetry of the eye lens, it was possible to reduce the measurement uncertainty. PMID:25111733

  3. Study on radionuclides in granite quarries of Bangalore rural district, Karnataka, India.

    PubMed

    Ningappa, C; Sannappa, J; Karunakara, N

    2008-01-01

    Studies on natural radiation levels and radionuclides were carried out extensively in the environment of granite quarries of Kanakapura, Ramanagara Taluks and Bidadi Hobli in Bangalore rural District and Bangalore city. The indoor and outdoor gamma exposure rate in air was measured using an environmental dosemeter, and it is converted into absorbed dose using suitable conversion factor. The activity concentrations of natural radionuclides in rock samples and also in soil samples were measured using an HPGe gamma-ray spectrometer. The results reveal that the activity concentrations of (226)Ra, (232)Th and (40)K in rocks are found to be vary from 32.2 to 163.6, 128.3 to 548.6 and 757.4 to 1418.4 Bq kg(-1), respectively, with corresponding arithmetic mean values of 93.2, 306.2 and 1074.4 Bq kg(-1). Activity concentrations of (226)Ra, (232)Th and (40)K in soil samples were found to vary from 32.4 to 55.2, 39.9 to 214.3 and 485.4 to 1150.2 Bq kg(-1), respectively, with corresponding arithmetic mean values of 40.7, 93.1 and 750.4 Bq kg(-1). The average activity levels of all these radionuclides are above the global average. This is consistent with the geological and geo-chemical significance of the rocks of the area under investigation. The results of these systematic investigations are discussed in detail and compared with the literature values represented for other environments. PMID:18682406

  4. Evolution of the CaF2:Tm (TLD-300) glow curve as an indicator of beam quality for low-energy photon beams

    NASA Astrophysics Data System (ADS)

    Muoz, I. D.; Avila, O.; Gamboa-deBuen, I.; Brandan, M. E.

    2015-03-01

    We study the high- to low- temperature signal ratio (HLTR) of the CaF2:Tm glow curve as a function of beam quality for low-energy photon beams with effective energy between 15.2 and 33.6?keV, generated with W, Mo and Rh anodes. CaF2:Tm dosemeters (TLD-300) were exposed to x-rays and 60Co gamma-rays. Glow curves were deconvoluted into 7 peaks, using computerized glow curve deconvolution and HLTR was evaluated. Air kerma and dose in water were between 2.1-15.0?mGy and 49.8-373.8?mGy, respectively. All peaks in the glow curve showed a linear response with respect to air kerma and dose in water. HLTR values decreased monotonically between 1.029? ?0.010 (at 15.2?keV) and 0.821? ?0.011 (33.6?keV), and no effects due to the use of different anode/filter combinations were observed. The results indicate a relatively high value of HLTR (about 1 for 17?keV effective energy, or 3?keV??m-1 track-average LET) and a measurable dependence on the photon beam quality. Comparison of these photon data with HLTR for ions shows good quantitative agreement. The reported evolution of the CaF2:Tm glow curve could facilitate the estimation of the effective energy of unknown photon fields by this technique.

  5. NUNDO: a numerical model of a human torso phantom and its application to effective dose equivalent calculations for astronauts at the ISS.

    PubMed

    Puchalska, Monika; Bilski, Pawel; Berger, Thomas; Hajek, Michael; Horwacik, Tomasz; Krner, Christine; Olko, Pawel; Shurshakov, Vyacheslav; Reitz, Gnther

    2014-11-01

    The health effects of cosmic radiation on astronauts need to be precisely quantified and controlled. This task is important not only in perspective of the increasing human presence at the International Space Station (ISS), but also for the preparation of safe human missions beyond low earth orbit. From a radiation protection point of view, the baseline quantity for radiation risk assessment in space is the effective dose equivalent. The present work reports the first successful attempt of the experimental determination of the effective dose equivalent in space, both for extra-vehicular activity (EVA) and intra-vehicular activity (IVA). This was achieved using the anthropomorphic torso phantom RANDO() equipped with more than 6,000 passive thermoluminescent detectors and plastic nuclear track detectors, which have been exposed to cosmic radiation inside the European Space Agency MATROSHKA facility both outside and inside the ISS. In order to calculate the effective dose equivalent, a numerical model of the RANDO() phantom, based on computer tomography scans of the actual phantom, was developed. It was found that the effective dose equivalent rate during an EVA approaches 700 ?Sv/d, while during an IVA about 20 % lower values were observed. It is shown that the individual dose based on a personal dosimeter reading for an astronaut during IVA results in an overestimate of the effective dose equivalent of about 15 %, whereas under an EVA conditions the overestimate is more than 200 %. A personal dosemeter can therefore deliver quite good exposure records during IVA, but may overestimate the effective dose equivalent received during an EVA considerably. PMID:25119442

  6. Evolution of the CaF?:Tm (TLD-300) glow curve as an indicator of beam quality for low-energy photon beams.

    PubMed

    Muoz, I D; Avila, O; Gamboa-deBuen, I; Brandan, M E

    2015-03-21

    We study the high- to low- temperature signal ratio (HLTR) of the CaF2:Tm glow curve as a function of beam quality for low-energy photon beams with effective energy between 15.2 and 33.6?keV, generated with W, Mo and Rh anodes. CaF2:Tm dosemeters (TLD-300) were exposed to x-rays and (60)Co gamma-rays. Glow curves were deconvoluted into 7 peaks, using computerized glow curve deconvolution and HLTR was evaluated. Air kerma and dose in water were between 2.1-15.0?mGy and 49.8-373.8?mGy, respectively. All peaks in the glow curve showed a linear response with respect to air kerma and dose in water. HLTR values decreased monotonically between 1.029? ?0.010 (at 15.2?keV) and 0.821? ?0.011 (33.6?keV), and no effects due to the use of different anode/filter combinations were observed. The results indicate a relatively high value of HLTR (about 1 for 17?keV effective energy, or 3?keV??m(-1) track-average LET) and a measurable dependence on the photon beam quality. Comparison of these photon data with HLTR for ions shows good quantitative agreement. The reported evolution of the CaF2:Tm glow curve could facilitate the estimation of the effective energy of unknown photon fields by this technique. PMID:25683355

  7. Shielding effect of thyroid collar for digital panoramic radiography

    PubMed Central

    Han, G-S; Cheng, J-G; Li, G

    2013-01-01

    Objectives: To evaluate the shielding effect of thyroid collar for digital panoramic radiography. Methods: 4 machines [Orthopantomograph OP200 (Instrumentarium Dental, Tuusula, Finland), Orthophos CD (Sirona Dental Systems GmbH, Bensheim, Germany), Orthophos XG Plus (Sirona Dental Systems GmbH) and ProMax (Planmeca Oy, Helsinki, Finland)] were used in this study. Average tissue-absorbed doses were measured using thermoluminescent dosemeter chips in an anthropomorphic phantom. Effective organ and total effective doses were derived according to the International Commission of Radiological Protection 2007 recommendations. The shielding effect of one collar in front and two collars both in front and at the back of the neck was measured. Results: The effective organ doses of the thyroid gland obtained from the 4 panoramic machines were 1.12??Sv for OP200, 2.71??Sv for Orthophos CD, 2.18??Sv for Orthophos XG plus and 2.20??Sv for ProMax, when no thyroid collar was used. When 1 collar was used in front of the neck, the effective organ doses of the thyroid gland were 1.01??Sv (9.8% reduction), 2.45??Sv (9.6% reduction), 1.76??Sv (19.3% reduction) and 1.70??Sv (22.7% reduction), respectively. Significant differences in dose reduction were found for Orthophos XG Plus and ProMax. When two collars were used, the effective organ doses of the thyroid gland were also significantly reduced for the two machines Orthophos XG Plus and ProMax. The same trend was observed in the total effective doses for the four machines. Conclusions: Wearing a thyroid collar was helpful when the direct digital panoramic imaging systems were in use, whereas for the indirect digital panoramic imaging systems, the thyroid collar did not have an extra protective effect on the thyroid gland and whole body. PMID:24005060

  8. SU-E-I-04: A Mammography Phantom to Measure Mean Glandular Dose and Image Quality

    SciTech Connect

    Lopez-Pineda, E; Ruiz-Trejo, C; E, Brandan M

    2014-06-01

    Purpose: To evaluate mean glandular dose (MGD) and image quality in a selection of mammography systems using a novel phantom based on thermoluminescent dosemeters and the ACR wax insert. Methods: The phantom consists of two acrylic, 19 cm diameter, 4.5 cm thick, semicircular modules, used in sequence. The image quality module contains the ACR insert and is used to obtain a quality control image under automatic exposure conditions. The dosimetric module carries 15 TLD-100 chips, some under Al foils, to determine air kerma and half-value-layer. TL readings take place at our laboratory under controlled conditions. Calibration was performed using an ionization chamber and a Senographe 2000D unit for a variety of beam qualities, from 24 to 40 kV, Mo and Rh anodes and filters. Phantom MGD values agree, on the average, within 3% with ionization chamber data, and their precision is better than 10% (k=1). Results: MGD and image quality have been evaluated in a selection of mammography units currently used in Mexican health services. The sample includes analogic (screen/film), flexible digital (CR), and full-field digital image receptors. The highest MDG are associated to the CR technology. The most common image quality failure is due to artifacts (dust, intensifying screen scratches, and processor marks for film/screen, laser reader defects for CR). Conclusion: The developed phantom permits the MGD measurement without the need of a calibrated ionization chamber at the mammography site and can be used by a technician without the presence of a medical physicist. The results indicate the urgent need to establish quality control programs for mammography.

  9. Effective radiation dose and eye lens dose in dental cone beam CT: effect of field of view and angle of rotation

    PubMed Central

    Zhang, G; Theodorakou, C; Walker, A; Bosmans, H; Jacobs, R; Bogaerts, R; Horner, K

    2014-01-01

    Objective: To quantify the effect of field of view (FOV) and angle of rotation on radiation dose in dental cone beam CT (CBCT) and to define a preliminary volume–dose model. Methods: Organ and effective doses were estimated using 148 thermoluminescent dosemeters placed in an anthropomorphic phantom. Dose measurements were undertaken on a 3D Accuitomo 170 dental CBCT unit (J. Morita, Kyoto, Japan) using six FOVs as well as full-rotation (360°) and half-rotation (180°) protocols. Results: For the 360° rotation protocols, effective dose ranged between 54 µSv (4 × 4 cm, upper canine) and 303 µSv (17 × 12 cm, maxillofacial). An empirical relationship between FOV dimension and effective dose was derived. The use of a 180° rotation resulted in an average dose reduction of 45% compared with a 360° rotation. Eye lens doses ranged between 95 and 6861 µGy. Conclusion: Significant dose reduction can be achieved by reducing the FOV size, particularly the FOV height, of CBCT examinations to the actual region of interest. In some cases, a 180° rotation can be preferred, as it has the added value of reducing the scan time. Eye lens doses should be reduced by decreasing the height of the FOV rather than using inferior FOV positioning, as the latter would increase the effective dose considerably. Advances in knowledge: The effect of the FOV and rotation angle on the effective dose in dental CBCT was quantified. The dominant effect of FOV height was demonstrated. A preliminary model has been proposed, which could be used to predict effective dose as a function of FOV size and position. PMID:25189417

  10. Techniques de dosimétrie physique pour la reconstitution d'accident radiologique

    NASA Astrophysics Data System (ADS)

    Bottollier-Depois, J. F.; Chau, Q.; Gaillard-Lecanu, E.; Médioni, R.; Roux, A.

    1998-04-01

    When a radiological accident occurred, the distribution of the dose received in the organism must be assessed within a short time. This information, which completes the clinical and biological investigations, is useful for the medical team. In this way, the physical dosimetry makes use of experimental and numerical reconstitution techniques which are generally complementary. The numerical technique consists in simulating the particles transport with a calculation code based on the Monte-Carlo method in a geometry which represents the injured person and the environment. The experimental reconstitution is performed with tissue equivalent phantoms and special dosemeters. Suite à un accident radiologique, il est important d'estimer rapidement la distribution de la dose reçue par l'organisme. Cette information, qui vient en complément des investigations cliniques et biologiques, s'avère d'une grande utilité pour les médecins. À cette fin, la dosimétrie physique utilise des moyens de reconstitution numériques et expérimentaux, généralement complémentaires. La reconstitution numérique consiste, à l'aide d'un code de calcul basé sur une méthode probabiliste de Monte-Carlo, à simuler le transport des particules dans une géométrie représentant l'accidenté et son evironnement. La reconstitution expérimentale est réalisée à l'aide de fantômes équivalents tissu et de dosimètres adaptés.

  11. Radiation exposure to patients and medical staff in hepatic chemoembolisation interventional procedures in Recife, Brazil.

    PubMed

    Khoury, H J; Garzon, W J; Andrade, G; Lunelli, N; Kramer, R; de Barros, V S M; Huda, A

    2015-07-01

    The purpose of this study was to evaluate patient and medical staff absorbed doses received from transarterial chemoembolisation of hepatocellular carcinoma, which is the most common primary liver tumour worldwide. The study was performed in three hospitals in Recife, capital of the state of Pernambuco, located in the Brazilian Northeastern region. Two are public hospitals (A and B), and one is private (C). For each procedure, the number of images, irradiation parameters (kV, mA and fluoroscopy time), the air kerma-area product (PKA) and the cumulative air kerma (Ka,r) at the reference point were registered. The maximum skin dose (MSD) of the patient was estimated using radiochromic film. For the medical staff dosimetry, thermoluminescence dosemeters (TLD-100) were attached next to the eyes, close to the thyroid (above the shielding), on the thorax under the apron, on the wrist and on the feet. The effective dose to the staff was estimated using the algorithm of von Boetticher. The results showed that the mean value of the total PKA was 267.49, 403.83 and 479.74 Gy cm(2) for Hospitals A, B and C, respectively. With regard to the physicians, the average effective dose per procedure was 17 Sv, and the minimum and maximum values recorded were 1 and 41 Sy, respectively. The results showed that the feet received the highest doses followed by the hands and lens of the eye, since the physicians did not use leaded glasses and the equipment had no lead curtain. PMID:25870436

  12. Assessment of GeB doped SiO2 optical fiber for the application of remote radiation sensing system

    NASA Astrophysics Data System (ADS)

    Alawiah, A.; Fadhli, M. M.; Bauk, S.; Abdul-Rashid, H. A.; Maah, M. J.

    2013-12-01

    The research and development efforts on the silica (SiO2) optical fiber for application in radiation sensing and other dosimetry field have become quite active. The widely used LiF based dosimeter (TLD) has shown a relatively low reproducibility and there is a time delay in dose assessment which loses its capability as direct real-time dose assessment dosimeters unlike diodes. The macroscopic size of the optical fiber generally does not allow direct in vivo dose sensing in the inner organ for radiotherapy and medical imaging. A flat optical fiber (FF) with nominal dimensions of (0.08 x10 x 10) mm3 of pure silica SiO2 and GeO2 with Boron doped silica fiber SiO2 was selected for this research. The Germanium was used a dopant to enhance the flat optical fiber to reach much higher responsiveness and dose sensitivity in high energy and high dose irradiation. Together with this combination, both TLD dimension and dose assessment issues was hoped to be overcome. The research conducted by comparing the response of pure silica SiO2 flat optical fiber with a GeO2 with Boron doped silica SiO2 flat optical fiber. The FF sample was annealed at 400°C for one hour before irradiated. Kinetic parameters and dosimetric glow curve of TL response and sensitivity were studied with respect to the electron beam of high dose of micro beam irradiation of 1.0 kGy, 5.0 kGy, 10.0 kGy, 50.0 kGy, 100.0 kGy, 500.0 kGy, and 1.0 MGy using Singapore Synchrotron Light Source's (PCIT) beamline. The PCIT operates at 500mA current with real time current range from 90-100mA, dose rate of 3.03 MGy/hour and energy at 8.9KeV. The source to Source Surface Distance (SSD) was at 6.0 cm, with a field size of 20mm × 8mm diameter of a half circle. The TL response was measured using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader was obtained to a preheat temperature of 150 °C for 5 s, the output signal being acquired at a temperature ramprate of 35 °Cs-1, acquisition time of 10 s and a maximum temperature of 400 °C each of the FF samples. All reading was taken under N2 gas flow, suppressing oxidation and potential triboluminescence. The proposed FF shows the excellent TL response for high energy irradiation and good reproducibility and exhibits a very low rate of fading and low variation background signal. From these results, the proposed FF can be used as a radiation dosimeter in remote radiation sensing and favorably compares with the widely used of LiF based dosimeter on common medical radiotherapy application.

  13. Determination of absorbed dose to water around a clinical HDR {sup 192}Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response

    SciTech Connect

    Carlsson Tedgren, Aasa; Elia, Rouba; Hedtjaern, Haakan; Olsson, Sara; Alm Carlsson, Gudrun

    2012-02-15

    Purpose: Experimental radiation dosimetry with thermoluminescent dosimeters (TLDs), calibrated in a {sup 60}Co or megavoltage (MV) photon beam, is recommended by AAPM TG-43U1for verification of Monte Carlo calculated absorbed doses around brachytherapy sources. However, it has been shown by Carlsson Tedgren et al.[Med. Phys. 38, 5539-5550 (2011)] that for TLDs of LiF:Mg,Ti, detector response was 4% higher in a {sup 137}Cs beam than in a {sup 60}Co one. The aim of this work was to investigate if similar over-response exists when measuring absorbed dose to water around {sup 192}Ir sources, using LiF:Mg,Ti dosimeters calibrated in a 6 MV photon beam. Methods: LiF dosimeters were calibrated to measure absorbed dose to water in a 6 MV photon beam and used to measure absorbed dose to water at distances of 3, 5, and 7 cm from a clinical high dose rate (HDR) {sup 192}Ir source in a polymethylmethacrylate (PMMA) phantom. Measured values were compared to values of absorbed dose to water calculated using a treatment planning system (TPS) including corrections for the difference in energy absorption properties between calibration quality and the quality in the users'{sup 192}Ir beam and for the use of a PMMA phantom instead of the water phantom underlying dose calculations in the TPS. Results: Measured absorbed doses to water around the {sup 192}Ir source were overestimated by 5% compared to those calculated by the TPS. Corresponding absorbed doses to water measured in a previous work with lithium formate electron paramagnetic resonance (EPR) dosimeters by Antonovic et al. [Med. Phys. 36, 2236-2247 (2009)], using the same irradiation setup and calibration procedure as in this work, were 2% lower than those calculated by the TPS. The results obtained in the measurements in this work and those obtained using the EPR lithium formate dosimeters were, within the expanded (k = 2) uncertainty, in agreement with the values derived by the TPS. The discrepancy between the results using LiF:Mg,Ti TLDs and the EPR lithium formate dosimeters was, however, statistically significant and in agreement with the difference in relative detector responses found for the two detector systems by Carlsson Tedgren et al. [Med. Phys. 38, 5539-5550 (2011)] and by Adolfsson et al.[Med. Phys. 37, 4946-4959 (2010)]. Conclusions: When calibrated in {sup 60}Co or MV photon beams, correction for the linear energy transfer (LET) dependence of LiF:Mg,Ti detector response will be needed as to measure absorbed doses to water in a {sup 192}Ir beam with highest accuracy. Such corrections will depend on the manufacturing process (MTS-N Poland or Harshaw TLD-100) and details of the annealing and read-out schemes used.

  14. Mammography dosimetry using an in-house developed polymethyl methacrylate phantom.

    PubMed

    Sharma, Reena; Sharma, Sunil Dutt; Mayya, Y S; Chourasiya, G

    2012-08-01

    Phantom-based measurements in mammography are well-established for quality assurance (QA) and quality control (QC) procedures involving equipment performance and comparisons of X-ray machines. Polymethyl methacrylate (PMMA) is among the best suitable materials for simulation of the breast. For carrying out QA/QC exercises in India, a mammographic PMMA phantom with engraved slots for keeping thermoluminescence dosemeters (TLD) has been developed. The radiation transmission property of the developed phantom was compared with the commercially available phantoms for verifying its suitability for mammography dosimetry. The breast entrance exposure (BEE), mean glandular dose (MGD), percentage depth dose (PDD), percentage surface dose distribution (PSDD), calibration testing of automatic exposure control (AEC) and density control function of a mammography machine were measured using this phantom. MGD was derived from the measured BEE following two different methodologies and the results were compared. The PDD and PSDD measurements were carried out using LiF: Mg, Cu, P chips. The in-house phantom was found comparable with the commercially available phantoms. The difference in the MGD values derived using two different methods were found in the range of 17.5-32.6 %. Measured depth ranges in the phantom lie between 0.32 and 0.40 cm for 75 % depth dose, 0.73 and 0.92 cm for 50 % depth dose, and 1.54 and 1.78 cm for 25 % depth dose. Higher PSDD value was observed towards chest wall edge side of the phantom, which is due to the orientation of cathode-anode axis along the chest wall to the nipple direction. Results obtained for AEC configuration testing shows that the observed mean optical density (O.D) of the phantom image was 1.59 and O.D difference for every successive increase in thickness of the phantom was within±0.15 O.D. Under density control function testing, at -2 and -1 density settings, the variation in film image O.D was within±0.15 O.D of the normal density setting '0' and at +2 and +1 density setting, it was observed to be within±0.30 O.D. This study indicates that the locally made PMMA TLD slot phantom can be used to measure various mammography QC parameters which are essentially required for better outcomes in mammography. PMID:22232773

  15. Irradiation of members of the general public from radioactive caesium following the Chernobyl reactor accident: Field studies in a highly contaminated area in the Bryansk region, Russia

    NASA Astrophysics Data System (ADS)

    Thornberg, Charlotte

    From 1990 to 1998, estimations of the effective dose due to irradiation from 137Cs and 134Cs were carried out for inhabitants in rural villages in the Bryansk region, Russia. The villages, situated about 180 km from the Chernobyl power plant received deposition of 137Cs in the range 0.9-2.7 MBq m-2 due to the accident in 1986. The body burden of 137,134Cs was estimated from measurements of the urinary concentration of caesium radionuclides, together with in vivo measurements using a portable detector. The external effective dose was estimated from measurements with thermoluminescent (TL)-dosemeters worn by the participants during one month each year. In a case study, the changes in biokinetics of 137Cs during pregnancy was investigated in a woman with an unintended intake of 137Cs via mushrooms grown in the area. During pregnancy the biological half-time of caesium was 54% of that before pregnancy. The ratio of the 137Cs concentration in breast milk (Bq L-1) to that in the mother's body (Bq kg-1) was 15% one month after the child was born. The body burden of 137Cs in the Russian individuals calculated from urine samples showed a good agreement with the body burden estimated from in vivo measurements in the same individuals. Normalisation of the caesium concentration in the urine samples by the use of potassium or creatinine excretion introduced systematic differences and a larger spread in the calculated values of the 137Cs body burden as compared with calculations without normalisation. The yearly effective dose to inhabitants in the Russian villages varied between 1.2 and 2.5 mSv as a mean for all villages between 1991 and 1998 and the internal effective dose was 30-50% of the total effective dose. The external effective dose decreased on average 15% per year, while the internal effective dose varied, depending to a great extent on the availability of mushrooms. The cumulated effective dose for a 70-year period after the accident was calculated to be 100 mSv assuming that the effective dose will decrease by only the physical decay of 137Cs (2% per year) after 1998. Individuals may receive considerably higher effective doses, up to 0.5 Sv during a life-time considering the large spread in dose values among individuals.

  16. A CCD-based optical CT scanner for high-resolution 3D imaging of radiation dose distributions: equipment specifications, optical simulations and preliminary results

    NASA Astrophysics Data System (ADS)

    Doran, Simon J.; Klein Koerkamp, Koen; Bero, Mamdouh A.; Jenneson, Paul; Morton, Edward J.; Gilboy, Walter B.

    2001-12-01

    Methods based on magnetic resonance imaging for the measurement of three-dimensional distributions of radiation dose are highly developed. However, relatively little work has been done on optical computed tomography (OCT). This paper describes a new OCT scanner based on a broad beam light source and a two-dimensional charge-coupled device (CCD) detector. A number of key design features are discussed including the light source; the scanning tank, turntable and stepper motor control; the diffuser screen onto which images are projected and the detector. It is shown that the non-uniform pixel sensitivity of the low-cost CCD detector used and the granularity of the diffuser screen lead to a serious ring artefact in the reconstructed images. Methods are described for eliminating this. The problems arising from reflection and refraction at the walls of the gel container are explained. Optical ray-tracing simulations are presented for cylindrical containers with a variety of radii and verified experimentally. Small changes in the model parameters lead to large variations in the signal intensity observed in the projection data. The effect of imperfect containers on data quality is discussed and a method based on a 'correction scan' is shown to be successful in correcting many of the related image artefacts. The results of two tomography experiments are presented. In the first experiment, a radiochromic Fricke gel sample was exposed four times in different positions to a 100 kVp x-ray beam perpendicular to the plane of imaging. Images of absorbed dose with slice thickness of 140 μm were acquired, with 'true' in-plane resolution of 560 × 560 μm2 at the edge of the 72 mm field of view and correspondingly higher resolution at the centre. The nominal doses measured correlated well with the known exposure times. The second experiment demonstrated the well known phenomenon of diffusion in the dosemeter gels and yielded a value of (0.12 +/- 0.02) mm2 s-1 for the diffusion coefficient of the xylenol orange/iron complex. Finally, the overall implications of the above findings for dosimetry using OCT are discussed.

  17. A CCD-based optical CT scanner for high-resolution 3D imaging of radiation dose distributions: equipment specifications, optical simulations and preliminary results.

    PubMed

    Doran, S J; Koerkamp, K K; Bero, M A; Jenneson, P; Morton, E J; Gilboy, W B

    2001-12-01

    Methods based on magnetic resonance imaging for the measurement of three-dimensional distributions of radiation dose are highly developed. However, relatively little work has been done on optical computed tomography (OCT). This paper describes a new OCT scanner based on a broad beam light source and a two-dimensional charge-coupled device (CCD) detector. A number of key design features are discussed including the light source; the scanning tank, turntable and stepper motor control; the diffuser screen onto which images are projected and the detector. It is shown that the non-uniform pixel sensitivity of the low-cost CCD detector used and the granularity of the diffuser screen lead to a serious ring artefact in the reconstructed images. Methods are described for eliminating this. The problems arising from reflection and refraction at the walls of the gel container are explained. Optical ray-tracing simulations are presented for cylindrical containers with a variety of radii and verified experimentally. Small changes in the model parameters lead to large variations in the signal intensity observed in the projection data. The effect of imperfect containers on data quality is discussed and a method based on a 'correction scan' is shown to be successful in correcting many of the related image artefacts. The results of two tomography experiments are presented. In the first experiment, a radiochromic Fricke gel sample was exposed four times in different positions to a 100 kVp x-ray beam perpendicular to the plane of imaging. Images of absorbed dose with slice thickness of 140 microm were acquired. with 'true' in-plane resolution of 560 x 560 microm2 at the edge of the 72 mm field of view and correspondingly higher resolution at the centre. The nominal doses measured correlated well with the known exposure times. The second experiment demonstrated the well known phenomenon of diffusion in the dosemeter gels and yielded a value of (0.12 +/- 0.02) mm2 s(-1) for the diffusion coefficient of the xylenol orange/iron complex. Finally, the overall implications of the above findings for dosimetry using OCT are discussed. PMID:11768500

  18. Skin dose measurements using radiochromic films, TLDS and ionisation chamber and comparison with Monte Carlo simulation.

    PubMed

    Alashrah, Saleh; Kandaiya, Sivamany; Maalej, Nabil; El-Taher, A

    2014-12-01

    Estimation of the surface dose is very important for patients undergoing radiation therapy. The purpose of this study is to investigate the dose at the surface of a water phantom at a depth of 0.007 cm as recommended by the International Commission on Radiological Protection and International Commission on Radiation Units and Measurement with radiochromic films (RFs), thermoluminescent dosemeters and an ionisation chamber in a 6-MV photon beam. The results were compared with the theoretical calculation using Monte Carlo (MC) simulation software (MCNP5, BEAMnrc and DOSXYZnrc). The RF was calibrated by placing the films at a depth of maximum dose (d(max)) in a solid water phantom and exposing it to doses from 0 to 500 cGy. The films were scanned using a transmission high-resolution HP scanner. The optical density of the film was obtained from the red component of the RGB images using ImageJ software. The per cent surface dose (PSD) and percentage depth dose (PDD) curve were obtained by placing film pieces at the surface and at different depths in the solid water phantom. TLDs were placed at a depth of 10 cm in a solid water phantom for calibration. Then the TLDs were placed at different depths in the water phantom and were exposed to obtain the PDD. The obtained PSD and PDD values were compared with those obtained using a cylindrical ionisation chamber. The PSD was also determined using Monte Carlo simulation of a LINAC 6-MV photon beam. The extrapolation method was used to determine the PSD for all measurements. The PSD was 15.03.6% for RF. The TLD measurement of the PSD was 16.05.0%. The (0.6 cm(3)) cylindrical ionisation chamber measurement of the PSD was 50.03.0%. The theoretical calculation using MCNP5 and DOSXYZnrc yielded a PSD of 15.02.0% and 15.72.2%. In this study, good agreement between PSD measurements was observed using RF and TLDs with the Monte Carlo calculation. However, the cylindrical chamber measurement yielded an overestimate of the PSD. This is probably due to the ionisation chamber calibration factor that is only valid in charged particle equilibrium condition, which is not achieved at the surface in the build-up region. PMID:24300340

  19. Simultaneous measurements of radon and thoron, and their progeny levels in dwellings on anticlinal structures of Assam, India.

    PubMed

    Barooah, Debajyoti; Barman, Simi; Phukan, Sarat

    2014-06-01

    Radon and thoron, and their progeny concentrations along with equilibrium factors for gas progeny and radiological risks to the residents have been measured in dwellings of Digboi and Mashimpur areas located on anticlines during the winter season. In this present investigation, twin-cup dosemeters fitted with LR-115 (II) nuclear detectors have been employed. The present work has shown that there exist considerable house-to-house variations in values with maximum values in mud houses and minimum values in assam type (AT) houses. It has been found that mean (and geometric standard deviations (GSD)) radon concentrations are 83.8 (1.3), 113.5 (1.1) and 157.2 (1.2) Bq m(-3) in AT, reinforced cement concrete (RCC) and mud houses in Digboi area and 63.0 (1.1), 87.1 (1.4) and 182.1 (1.2) Bq m(-3) in AT, RCC and mud houses in Mashimpur area, respectively. The overall mean radon concentrations in Digboi and Mashimpur are estimated to be 114.4 (1.4) and 100.0 (1.7) Bq m(-3). The mean radon concentrations are found to be less than the lower reference level of 200 Bq m(-3) of the International Commission on Radiological Protection (ICRP 2007). The thoron concentrations in Digboi area are estimated to be 31.1 (1.3), 50.8 (1.4) and 67.0 (1.6) Bq m(-3) in AT, RCC and mud houses, respectively, whereas in Mashimpur area, the thoron concentrations are estimated to be 26.4 (1.3), 44.4 (1.3) and 77.7 (1.3) Bq m(-3) in AT, RCC and mud houses, respectively. The mean annual effective doses in Digboi area are found to be 1.9 (1.3), 2.7 (1.2) and 4.1 (1.4) mSv y(-1) in AT, RCC and mud houses, respectively, while in the case of Mashimpur area, the mean annual effective doses are found to be 1.5 (1.4), 2.2 (1.2) and 4.9 (1.3) mSv y(-1) in AT, RCC and mud houses, respectively. Nevertheless, the obtained results are much lower than the upper reference level of 10 mSv (ICRP 2007). PMID:24469015

  20. Cosmic Radiation and Aircrew Exposure: Implementation of European Requirements in Civil Aviation, Dublin, 1-3 July 1998

    NASA Astrophysics Data System (ADS)

    Talbot, Lee

    1999-03-01

    The European Union's Basic Safety Standards Directive (96/29/Euratom) lays down safety standards for the protection of workers and the general public against the effects of ionising radiations. Article 42 of the Directive deals with the protection of aircrew. It states that for crew of jet aircraft who are likely to be subject to exposure to more than 1 mSv y-1 appropriate measures must be taken, in particular: to assess the exposure of the crew concerned, to take into account the assessed exposure when organising working schedules with a view to reducing the doses of highly exposed aircrew, to inform concerned workers of the health risks involved in their work, to apply Article 10 to female aircrew. (The unborn child shall be treated like a member of the public.) This Directive must be transformed into national law of the 15 member states of the European Union by 13 May 2000. The European Commission and the Radiological Protection Institute of Ireland sponsored this International Conference. The objective of this conference was to assist both the airline industry and the national regulatory organisations in identifying the means available to comply with the requirements of the Directive. Over 200 delegates attended the conference from more than 25 countries. The welcoming addresses were made by Mary Upton (Director of the Radiological Protection Institute of Ireland), Joe Jacob (Minister for State responsible for Nuclear Safety) and James Currie (Director-General for the Environment, Nuclear Safety and Civil Protection). Mr Currie stated that there was a need for political decisions to be based on good science, and that technological trends will lead to higher and longer flights, and therefore higher radiation doses. The first day concentrated on the scientific basis of measurement, calculation and monitoring of cosmic radiation. The first speaker, Dr Heinrich from the University of Siegen, Germany, talked about the physics of cosmic radiation fields. He pointed out that of all the particles that come from outside our solar system 85% are hydrogen, 12.5% are helium and 1.5% are heavier particles. The flux of these particles changes over the 11-year solar cycle: if the solar activity is high then the cosmic radiation flux is low. The Earth's geomagnetic field affects whether or not a particle will reach the Earth. The nearer the equator, the higher the cut-off rigidity and hence the greater the shielding. At the poles the cut-off rigidity is at its lowest, hence the greater the number of particles which reach the Earth. The speaker summarised by saying that in order to make an accurate assessment of the radiation dose due to cosmic radiation one must know which primary cosmic rays are involved, the solar modulation effects, the geomagnetic shielding and particle interactions in the atmosphere. Alternatively dosimetric measurements can be made at different altitudes, latitudinal and longitudinal positions for the most relevant radiation components. The second speaker of the morning, Dr Hilton Smith, the Ex-Scientific Secretary of the ICRP, gave a talk entitled `Quantifying Radiation Risk'. The talk started by explaining that high LET radiations have a greater probability of causing DNA damage than low LET radiations and that DNA can be damaged in a number of ways: the single-strand break, two single-strand breaks, the double-strand break (the hallmark of ionising radiation) and base damage. The possible effects of these interactions are the death of the cell, inhibition of cellular division and change in cell structure. The physical and chemical effects occur over very short periods, but the biological effects may not be noticed for many years. The speaker described risk estimation based on A-bomb survivors, medical therapy, medical diagnosis of patients, occupational studies of uranium miners and radium workers. The human fatal cancer risk has been calculated by the ICRP to be 5% Sv-1 for the public. The maximum likelihood of cancer occurring is at age 70. At the end of the presentation there was a discussion on whether or not protons of a certain energy should have a quality factor of 5. It was suggested that the factor should be equal to one. Dr Bartlett of the NRPB gave the next talk on Radiation Protection Concepts and Quantities for Occupational Exposure to Cosmic Radiation. Dr Bartlett explained that there are significant differences between the exposure condition of aircrew and occupational exposure generally. There are a greater range of radiation types and energies. Half of aircrews' doses are due to neutrons. UK Classified radiation workers receive 2% of their dose from high LET radiations and aircrew receive 50%. Dose distributions and characteristics of the working populations are different, with 53% of aircrew being female, as opposed to 7% of Classified UK radiation workers. The field intensity on aircraft is predictable, and, with the exception of rare solar flare events, there is no risk of accidental exposures. The speaker highlighted the variation in cosmic radiation dose as a function of altitude illustrated by the radiation doses at 15, 10 and 6.7 km being 10, 5 and 1 µSv h-1. It was interesting to note the comparison made between the average radiation dose of 1 mSv y-1 in the nuclear industry and 2 mSv y-1 for aircrew. The speaker said that it is necessary to appreciate that people living in high radon areas in the UK receive approximately 8 mSv per year. Dr Bartlett highlighted how the requirements for the protection of aircrew from the Basic Safety Standard Directive (BSS96) differed from those for occupational exposures in general, namely that there are not explicit dose limits, other than that to be applied to the exposure of the foetus. There are no requirements for the designation of areas or classification of workers and there is no reference to the principle of ALARA, but there is a requirement to take account of the assessed exposure when arranging work schedules with a view to reducing higher doses. Dr Bartlett summed up by saying that dose assessment will probably be done by folding roster information with estimates of route doses. The last speaker of the morning session was Dr Maria Blettner, from the International Agency for Research on Cancer, Lyon, France. She talked about epidemiological studies for individuals occupationally exposed to radiation. The speaker emphasised that the results of early studies regarding cancer mortality are equivocal; elevated cancer risks have been observed in some studies, but not in others. The low cumulative dose up to 100 mSv is associated with poor statistics. Therefore it is difficult to calculate the relative risk of exposure with a high degree of confidence. The speaker also highlighted the difficulty in obtaining a comparison population since aircrews have characteristics and lifestyles that differ from the general population. The speaker stressed the need for large studies in this field of epidemiology. Dr Blettner summarised her speech by saying that the results of a cohort of some 22 000 pilots and 47 000 crewmembers can be formed from the workers in nine different countries and that pooled analyses are expected in 2001. The next speaker was Dennis O'Sullivan, from the Dublin Institute of Advanced Studies, who gave a talk entitled `Overview and Present Status of EC Research Programme'. The objectives of the EC programme were highlighted as follows: to develop and calibrate instrumentation for use at altitude, to measure flux and energy spectra of neutrons and charged particles, to measure LET spectra and ambient dose equivalent, to estimate dose contribution by solar particle events and finally to compare results with calculations. The airlines involved in these studies were Aer Lingus, Alitalia, BA, Lufthansa and Scandinavia Airlines. Tests were carried out on several routes, on both subsonic and supersonic aircraft. A detailed set of measurements were obtained over a five-year period. Professor O'Sullivan said that the NRPB used TLDs for low and high LET radiations and PADC for neutrons. The investigation of dosemeter response was carried out using Monte Carlo codes. The active instruments used for measurements were the tissue equivalent proportional counter (TEPC) and a Bonnersphere spectrometer using eight spheres. The instrumentation used was calibrated in the CERN-CEC reference field. In summary, it was found that the shape of the neutron spectrum does not change with altitudes and that the maximum dose rate was found to be under the seats of the aircraft. Dr Lindbourg of the Swedish Radiation Protection Institute gave a short talk on the importance of using the TEPC for cosmic ray measurements, as it is the only means of reading directly absorbed dose to tissue and the radiation quality (in terms of lineal energy). Dr Schewe from PTB, Germany, gave the next talk on reference fields and calibration procedures. The speaker highlighted the difficulties in measuring radiation fields onboard aircraft, as the calibration fields used are often vastly different to the radiation field the instrumentation is being exposed to. The speaker said that this could lead to errors in the measurements in excess of 50%. One way around this is to use realistic reference fields, which produce similar particle compositions and particle fluences as those present in the cosmic radiation at aircraft altitudes. For this work the reference field facility in one of the secondary beams lines of the CERN Super Proton Synchrotron was used. In summary it was shown that the TEPC could be used as a reference instrument for evaluating ambient dose equivalent in aircraft. The next speaker was Dr Tommasino of the ANPA, Rome, who talked about in-flight measurement of radiation fields and doses. He stated that the problem of radiation dose assessment has been developed within the multinational research programmes of the Commission of the European Communities. The speaker talked about the different dosimetric systems formed by the TEPC, ANPA-stack, DIAS-stack and Extended Rem-counter. The ANPA-stack and DIAS-stack detectors have been developed under the CEC research programme specifically for the measurement of cosmic radiation on aircraft. The experiments were carried out between 1994 and 1997 at the period of the solar minimum, and therefore represent an upper limit on the dose due to galactic cosmic rays. The speaker gave an example of a flight from Tokyo to Milan, where the ambient dose equivalent was 4.83 µSv h-1 and the annual dose, assuming a 700 hour year, was 3.38 mSv y-1. In conclusion the speaker said that the measurements from all four dosimetric systems were consistent. Dr Schraube from the National Research Centre for Environment and Health, Germany, gave the last presentation of the day, on the experimental verification and calculation of route doses. The verification was restricted to neutrons. The speaker showed that theoretical calculations could be matched to experimental data. Therefore the fluences at all positions of interest in the Earth's atmosphere could be calculated. It was then possible to calculate the doses on aviation routes using the computer package European Program for the Calibration of Aviation Route Dose (EPCARD). The second day of the conference concentrated on the airline industry perspective of the cosmic radiation problem. The first speaker was B Lecouturier, of the Federation des Syndicats de Transport, Brussels. She gave an introductory presentation on the view of cabin crew. The speaker highlighted the inconsistency of some EU states: for example, some states insist that pregnant workers stop flying, while others do not. In conclusion the speaker said that cabin crew wish for a correct assessment of their cosmic radiation dose, medical surveillance and further epidemiological studies. The second speaker of the day was Dr Balouet, also from the Federation des Syndicats de Transport, Brussels. His talk was entitled, `Ionising Radiations and Cabin Crew Concerns'. The main concerns of cabin crews were as follows: uncertainty in the quality factor for neutrons, heavy ions are not taken into account when calculating radiation doses, 25-60% of some routes if flown for a standard working year could exceed the 6 mSv level, European crew flying on non-European airlines, solar flares, which give relatively high radiation exposures. The next speaker was Wallace Friedberg of the Civil Aeromedical Institute, USA, who gave a talk on the guidelines provided by the FAA to promote radiation safety for Air Carrier Crewmembers. Wallace recalled the information the FAA has provided, including: (a) guidelines for air carrier training programmes on in-flight radiation exposure, including recommended radiation exposure limits; (b) estimates of the galactic radiation dose received on a wide variety of air carrier flights; (c) tables for estimating healthy risks from galactic radiation exposure; and (d) support for research on the effects of irradiation during pregnancy, including possible galactic radiation effects on the reproductive health of female flight attendants. The speaker highlighted the availability of a computer program (CARI) available to the general public, which can be used for estimating the galactic radiation dose received from a non-stop flight between any two locations in the world. Sandy Mitchell of the European Cockpit Association was the next speaker. He gave a talk on the concept of `As Low as Reasonably Achievable' in relation to cosmic radiation. The speaker began by saying that aviation activity was increasing by 5% per annum and flights below 25 000 ft pose no radiation exposure problem. The speaker then drew attention to the strategies that could be employed to reduce radiation exposure, which include restriction of altitude to 31 000 ft, restriction of annual flying hours to 500 hours, increased aircraft shielding, fitting all aircraft with active monitoring and the introduction of annual medical examinations for aircrew. It was also suggested by the speaker that pregnant flying aircrew could undertake ground duties or be given unpaid leave. Alternatively, they could be transferred to regional routes where doses are very low. The speaker concluded by performing a cost-benefit analysis of reducing the cruising altitude of aircraft. This lead to increased fuel consumption but reduced collective dose. It was shown that the collective dose reduction would not be great enough to justify the costs incurred. The session after lunch concentrated on the airlines and the air industry. Dr Oksanen of Finnair gave the fist lecture of this session in a talk entitled `The Operator: Experiences and Views'. The speaker began by summarising the Association of European Airlines (AEA) involvement in cosmic radiation, which has included dose measurement and estimation, production of educational material and epidemiological studies. The speaker talked about the differing methods of route dose estimation using active monitoring, passive monitoring and computer modelling. The AEA airlines believe that the EURATOM Directive may best be implemented by route dose estimation using a common mathematical model. This would have the advantage that modelling is accepted worldwide as a credible and practical method of dose estimates and overcomes the logistic problems, the likelihood of equipment failure and error inherent in direct measurement. In addition, it allows for consistency of route dose estimates among various airlines and finally offers the opportunity for independent scrutiny and audit required. Michael Bagshaw, the Head of Medical Services for British Airways, gave a very interesting talk on in-flight measurements. Mr Bagshaw began by talking about the cosmic ray detection methods used on the Concorde, consisting of GM tubes and boron trifluoride detectors. The information from these detectors is then fed directly to the pilot. The system alarms at 500 µSv h-1. However, since Concorde entered service in 1976 no Concorde has had to reduce altitude due to cosmic radiation. Mr BAGSHAW said the effective dose when averaged over 113 flights was 13 µSv h-1, with the London to New York route dose being 43 µSv h-1. On average flight crew get 3-4 mSv y-1 and cabin crews get 2-3 mSv y-1. Interestingly, it is BA policy to ground crew on the declaration of pregnancy. A crewmember who does not declare she is pregnant may still fly, even if she knows she is pregnant. A pregnant crewmember therefore has a choice. Christopher Hume from British Aerospace gave a short presentation regarding the manufacturer's perspective. A number of issues that are going to increase cosmic radiation dose were highlighted. Future aircraft are going to fly at much higher altitudes, the BIZ JET is going to fly at 60 000 ft and the SCT is going to fly at 70 000 ft. Some new routes may go directly over the North Pole. The speaker mentioned that shielding of the aircraft in order to reduce doses was impractical. Clive Dyer from the DERA Space Department in Farnborough made an unscheduled and very interesting presentation concerning the cosmic radiation effects on avionics. He stated that there are common links between the interaction of radiation within electronics and that within tissue at the DNA level. His talk described the different ways in which ionising radiation can interact with electronics and cause a number of different effects, including bit-flips, destructive burn-out, gate rupture and dielectric failure. Professor Dyer mentioned that the reduction in component size means larger upsets in the electronics. The speaker then concentrated on single-event effects on equipment in space, where the problems were first predicted in 1962 and observed in 1975. PCs on the Space Shuttle and Mir require frequent reboot, typically every nine hours. The speaker concluded by saying that single-event effects can now be seen at ground level because of the design of modern computer chips. The final day concentrated on regulatory aspects. L Bergau, from the Medical Department of Lufthansa German Airlines, gave the first talk on medical aspects. His study involved the comparison of female aircrew and female ground crew. The study excluded anyone who had undergone medical treatment with ionising radiation and heavy smokers. Two thousand cells from each individual were scored. The results showed that the numbers of dicentrics were the same in the cabin crew, aircrew and ground crew, demonstrating that the low cosmic radiation exposures seem not to increase cancer risk. Mr Ulback from the National Institute of Radiation Hygiene, Denmark, gave the next speech. His talk was simply entitled `Radiation Protection'. The speaker outlined how the legislation had been derived from the ICRP, through the EU commission and EU council, and finally adopted in the legislation of the member states. The final speaker, Mr Courades from the European Commission, spoke about EU legislation. Mr Courades said that the EU Directive would affect more states than are currently members because other countries wish to become part of the EU. It was highlighted that Article 42 applied only to aircrew (civilian and military) and not passengers. It was also pointed out that classification of the workplace is not required onboard aircraft. Mr Courades said that it was difficult to have a generic dose for a specific flight because of `free flight' where an aircraft changes altitude frequently. The speaker summed up by stressing the need for a common implementation of the directive.