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Sample records for harshaw tld-700h dosemeters

  1. 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

  2. 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.

  3. Uncertainties in dosemeter intercomparison techniques

    NASA Astrophysics Data System (ADS)

    Harrison, R. M.; Rawlings, D. J.

    1996-03-01

    The results of 180 intercomparisons of field dosemeters with an NPL secondary-standard exposure meter (type 2560, with a type 2561 chamber) have been analysed in order to study variations in readings when ionization chambers are interchanged during the comparison process. It is suggested that the percentage standard error of the mean of the combined series of chamber intercomparisons be used to set a target uncertainty (0.3%), action level (0.5%) and limit of acceptability (1.0%). The target uncertainty is consistent with IAEA estimates of uncertainty for this part of the calibration chain. It is shown that if the calibration procedure is repeated, the percentage difference between the geometric means calculated from each calibration (i.e. a single interchange of chambers) may be as high as . This reinforces the need for at least one repetition of the intercomparison procedure.

  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. 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

  6. 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.

  7. 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.

  8. 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.

  9. Factories: The Ionising Radiations (Sealed Sources) (Radiation Dosemeter and Dose Rate Meter) Order, 1961 

    E-print Network

    Hare, John

    1961-01-01

    This Order prescribes the particulars to be contained In registers kept in pursuance of paragraph (3) of Regulation 13 of the Ionising Radiations (Sealed Sources) Regulations, 1961, of every test of a radiation dosemeter ...

  10. An estimate of the propagated uncertainty for a dosemeter algorithm used for personnel monitoring.

    PubMed

    Veinot, K G

    2015-03-01

    The Y-12 National Security Complex utilises thermoluminescent dosemeters (TLDs) to monitor personnel for external radiation doses. The TLD consist of four elements positioned behind various filters, and dosemeters are processed on site and input into an algorithm to determine worker dose. When processing dosemeters and determining the dose equivalent to the worker, a number of steps are involved, including TLD reader calibration, TLD element calibration, corrections for fade and background, and inherent sensitivities of the dosemeter algorithm. In order to better understand the total uncertainty in calculated doses, a series of calculations were performed using certain assumptions and measurement data. Individual contributions to the uncertainty were propagated through the process, including final dose calculations for a number of representative source types. Although the uncertainty in a worker's calculated dose is not formally reported, these calculations can be used to verify the adequacy of a facility's dosimetry process. PMID:25009187

  11. Quality assurance of personal beta particle dosemeters used for individual monitoring of occupationally exposed persons.

    PubMed

    Helmstädter, Klaus; Ambrosi, Peter

    2007-01-01

    As a result of investigations and intercomparison measurements organised from 1996 to 1999 by PTB, several types of personal dosemeters, all based on TLD, were selected by the dosimetry services for the measurement of the personal dose equivalent Hp(0.07) in beta and/or photon radiation fields. These dosemeters have now the status of legal personal beta partial-body dosemeters. Workplaces at which beta radiation might significantly contribute to the doses to the extremities are to be found today with increasing frequency in radiation therapy, radiation source production and nuclear power plants. Quality assurance for beta personal dosemeters is stipulated by guidelines for the official dosimetry service and is carried out by way of the intercomparison measurements organised periodically by the PTB. The results are evaluated based on the recommendations of the German Commission on Radiological Protection (SSK). The procedure of these intercomparison measurements will be explained in detail. The experience gained from three series of comparisons with seven types of fingerring dosemeters will be described and the results will be presented. The anonymity of the dosemeter types and of the participants in the intercomparison will be preserved. PMID:17337739

  12. Personal neutron dosimetry in nuclear power plants using etched track and albedo thermoluminescence dosemeters.

    PubMed

    Fernández, F; Bakali, M; Amgarou, K; Nourreddine, A; Mouhssine, D

    2004-01-01

    Measurement of the personal dose equivalent rates for neutrons is a difficult task because available dosemeters do not provide the required energy response and sensitivity. Furthermore, the available wide calibration spectra recommended by the International Standard Organisation does not reproduce adequately the spectra encountered in practical situations of the nuclear industry. There is a real necessity to characterise the radiation field, in which workers can be exposed, and to calibrate personal dosemeters in order to determine the dose equivalent in these installations. For this reason, we measure the neutron spectrum with our Bonner sphere system and we fold this spectrum with energy-dependent fluence-to-dose conversion coefficients to obtain the reference dose equivalent rate. This reference value is then compared with the personal dosemeter reading to determine a field-specific correction factor. In this paper, we present the values of this field-specific correction factor for etched track and albedo thermoluminescence dosemeters at three measurement locations inside the containment building of the Vandellňs II nuclear power plant. We have found that assigning to each personal dosemeter the mean value of the field-specific correction factors of the three measurement locations, allows the evaluation of neutron personal dose equivalent rate with a relative uncertainty of approximately 25 and 15% for the PADC and albedo dosemeters, respectively. PMID:15353734

  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. 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

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

    PubMed

    Principi, Sara; Ginjaume, Mercč; 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

  16. Dissolution behaviour of 238U, 234U and 230Th deposited on filters from personal dosemeters.

    PubMed

    Becková, Vera; Malátová, Irena

    2008-01-01

    Kinetics of dissolution of (238)U, (234)U and (230)Th dust deposited on filters from personal alpha dosemeters was studied by means of a 26-d in vitro dissolution test with a serum ultrafiltrate simulant. Dosemeters had been used by miners at the uranium mine 'Dolní Rozínka' at Rozná, Czech Republic. The sampling flow-rate as declared by the producer is 4 l h(-1) and the sampling period is typically 1 month. Studied filters contained 125 +/- 6 mBq (238)U in equilibrium with (234)U and (230)Th; no (232)Th series nuclides were found. Half-time of rapid dissolution of 1.4 d for (238)U and (234)U and slow dissolution half-times of 173 and 116 d were found for (238)U and (234)U, respectively. No detectable dissolution of (230)Th was found. PMID:17974580

  17. Field calibration of dosemeters used for routine measurements at flight altitudes.

    PubMed

    Wissmann, F; Burmeister, S; Dönsdorf, E; Heber, B; Hubiak, M; Klages, T; Langner, F; Möller, T; Meier, M

    2010-08-01

    Intercomparisons of dosemeters used in radiation protection are performed routinely in reference radiation fields under well-defined conditions. In the case of the radiation protection of aircrew members, such reference fields either do not exist or they can be partially simulated by accelerator-based fields. Another method is to perform simultaneous measurements on board an aircraft under constant flight conditions, i.e. at defined latitude, longitude and altitude. The intercomparison presented in this work is the second one of its kind. As reference instruments, two types of tissue-equivalent proportional counters (TEPC) were used in comparison with different silicon detector systems. The excellent agreement of the FDOScalc code, which is based on measurements made by PTB during different phases of solar cycle 23 with the TEPC measurements and the results of the preceding project "Coordinated Access to Aircraft for Transnational Environmental Research" (CAATER) even allows the in-field calibration of the Si dosemeters. PMID:20484163

  18. 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

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

    PubMed

    Krins, A; Dörschel, 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

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

    PubMed

    Olšovcová, V; Klír, D; Krása, 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

  1. Brazilian gamma-neutron dosemeter: response to 241AmBe and 252Cf neutron sources.

    PubMed

    Souto, E B; Campos, L L

    2011-03-01

    With the aim of improving the monitoring of workers potentially exposed to neutron radiation in Brazil, the IPEN/CNEN-SP in association with PRO-RAD designed and developed a passive individual gamma-neutron mixed-field dosemeter calibrated to be used to (241)AmBe sources. To verify the dosimetry system response to different neutron spectra, prototypes were irradiated with a (252)Cf source and evaluated using the dose-calculation algorithm developed for (241)AmBe sources. PMID:21186217

  2. 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

  3. 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.

  4. Spectral correction factors for conventional neutron dosemeters used in high-energy neutron environments.

    PubMed

    Lee, K W; Sheu, R J

    2015-04-01

    High-energy neutrons (>10 MeV) contribute substantially to the dose fraction but result in only a small or negligible response in most conventional moderated-type neutron detectors. Neutron dosemeters used for radiation protection purpose are commonly calibrated with (252)Cf neutron sources and are used in various workplace. A workplace-specific correction factor is suggested. In this study, the effect of the neutron spectrum on the accuracy of dose measurements was investigated. A set of neutron spectra representing various neutron environments was selected to study the dose responses of a series of Bonner spheres, including standard and extended-range spheres. By comparing (252)Cf-calibrated dose responses with reference values based on fluence-to-dose conversion coefficients, this paper presents recommendations for neutron field characterisation and appropriate correction factors for responses of conventional neutron dosemeters used in environments with high-energy neutrons. The correction depends on the estimated percentage of high-energy neutrons in the spectrum or the ratio between the measured responses of two Bonner spheres (the 4P6_8 extended-range sphere versus the 6? standard sphere). PMID:25280480

  5. Portable x-ray spectrometer/dosemeter based on a silicon diode

    SciTech Connect

    Eisen, Y.; Olsher, R.H.; Brake, R.J.; Littlejohn, G.J.; Meddles, A.

    1987-01-01

    We developed a portable x-ray spectrometer/dosemeter based on a silicon p-i-n diode. The instrument is capable of obtaining spectral information in the region from 18 keV to 150 keV and measuring photon exposures in the region from 18 keV to 1.3 MeV. A theoretical method is described for obtaining a nearly air equivalent response in the energy region above 18 keV. The instrument has a dynamic range for most energies between 0.5 mR/h and 5 R/h. Its small size, ability to provide spectroscopic output, and satisfactory air equivalent response over a wide energy range, make this instrument more attractive than portable ionization chambers.

  6. 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

  7. Track-etch dosemeter response to neutrons up to 300 MeV

    SciTech Connect

    Devine, R.T.; Walker, S.; Staples, P.; Duran, M.; Mundis, R.; Miller, J.

    1996-04-01

    Electro-chemical and chemical track-etch dosemeters were obtained from commercial suppliers and exposed to neutrons produced at the LANTF WNR white neutron source at 15{degree} with no shielding and filtered by polyethylene blocks of 2.5, 5.1, 10.2, 20.3 and 40.6 cin thickness. The neutron spectrum was determined using calculations. Mean energies from 28 to 300 MeV were produced. Dose was calculated from the NCRP-38 flux-to-dose conversion. The results are compared with NTA film which was exposed in the same configuration. The response of track etch dosimeters was found to reach a minimum and then rise as the average neutron energy increased. The response of the NTA film increased as the neutron energy increased.

  8. 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.

  9. 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?µSv and the MOSFET doses between 6.1 and 175.0?µSv. The MOSFET and TLD effective doses acquired using four different (FOV) protocols were as follows: face maxillofacial (FOV 20?×?17?cm) (MOSFET, 83.4?µSv; TLD, 87.6?µSv; ?5%); teeth, upper jaw (FOV, 8.5?×?5.0?cm) (MOSFET, 6.1?µSv; TLD, 7.0?µSv; ?14%); tooth, mandible and left molar (FOV, 4?×?5?cm) (MOSFET, 10.3?µSv; TLD, 12.3?µSv; ?16%) and teeth, both jaws (FOV, 10?×?10?cm) (MOSFET, 175?µSv; TLD, 158?µSv; +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

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

    PubMed

    Vörös, Sándor; Anton, Mathias; Boillat, Bénédicte

    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 (D(W)) response of the dosemeter needs to be known for relevant radiation qualities. For MeV electrons, the D(W) 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 D(W) 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 D(W) response was found in the range between 6 and 20?MeV. It is therefore suggested to use a unique correction factor k(E) for alanine for all MeV qualities of k(E) = 1.012 ± 0.010. PMID:22349609

  11. 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

  12. 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.

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

    PubMed

    Lahaye, T; Chau, Q; Ménard, 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 Krümmel 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 Belgonucléaire, a fuel processing factory. PMID:16820401

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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 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.

  2. 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.

  3. 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)

  4. 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.

  5. TECHNICAL RESPONSE ANIMAL COGNITION

    E-print Network

    Napp, Nils

    TECHNICAL RESPONSE ANIMAL COGNITION Response to Comments on "Number-space mapping in the newborn concerns are not founded. Harshaw suggests that a side bias could have affected our results. We show/17; overall 24/30, P bias may be related to feeding

  6. 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.

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

    PubMed

    Luszik-Bhadra, M; Zimbal, A; Busch, F; Eichelberger, A; Engelhardt, J; Figel, M; Frasch, G; Günther, 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

  8. Personal neutron dosimetry at a research reactor facility.

    PubMed

    Kamenopoulou, V; Carinou, E; Stamatelatos, I E

    2001-01-01

    Individual neutron monitoring presents several difficulties due to the differences in energy response of the dosemeters. In the present study, an individual dosemeter (TLD) calibration approach is attempted for the personnel of a research reactor facility. The neutron energy response function of the dosemeter was derived using the MCNP code. The results were verified by measurements to three different neutron spectra and were found to be in good agreement. Three different calibration curves were defined for thermal, intermediate and fast neutrons. At the different working positions around the reactor, neutron spectra were defined using the Monte Carlo technique and ambient dose rate measurements were performed. An estimation of the neutrons energy is provided by the ratio of the different TLD pellets of each dosemeter in combination with the information concerning the worker's position; then the dose equivalent is deduced according to the appropriate calibration curve. PMID:11586728

  9. Conceptual design of spectrum changeable neutron calibration fields in JAERI/FRS.

    PubMed

    Saegusa, J; Tanimura, Y; Yoshizawa, M; Yoshida, M

    2004-01-01

    Spectrum changeable neutron calibration fields are planned to be established with an accelerator installed in Japan Atomic Energy Research Institute/Facility of Radiation Standards. The neutron fields are provided by bombarding a target surrounded by a moderator, with charged particles from the accelerator. In the fields, a wide variety of neutron spectra is provided with sufficient fluence rate for the calibration of dosemeters. In this study, necessity of the field was first discussed in view of relationship between readings of existing dosemeters and true dose equivalents where the dosemeters were used. Second, test simulation of neutron spectra was carried out with the Monte Carlo technique for some arrangements with a LiF target and quasi-cylindrical moderators with different materials. The simulated spectra were summarised in terms of fluence-average energy, fluence rate and calibration factor for the dosemeters. PMID:15353628

  10. Comparison of commercial thermoluminescent readers regarding high-dose high-temperature measurements

    E-print Network

    Bilski, P; Obryk, B; Hodyr, K

    2014-01-01

    Three different thermoluminescent measuring systems have been compared with respect to the differences in temperature profiles, spectral sensitivities, as well as linearity of dose response characteristics. The comparison was performed using the Harshaw 3500, Riso DA-20 and RA94 TLD readers. The instruments were tested for the readouts of highly irradiated LiF:Mg,Cu,P (MCP) TL detectors, which require readout up to 550 C, in case of doses exceeding 1 kGy. It was found that the Harshaw 3500 can be used, without any additional light attenuation, for the measurements of MCP detectors exposed to doses up to about 5 Gy. For the other two readers the upper dose limit is about 5 times lower. It was also found that the Harshaw 3500 shows the best thermal stability considering the peak maximum position. For the ultra-high doses the differences in the spectral characteristics of the applied optical filters and photomultipliers, in conjunction with an evolution of the MCP TL emission spectrum with increasing dose, signi...

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Estimation of staff lens doses during interventional procedures. Comparing cardiology, neuroradiology and interventional radiology.

    PubMed

    Vano, E; Sanchez, R M; Fernandez, J M

    2015-07-01

    The purpose of this article is to estimate lens doses using over apron active personal dosemeters in interventional catheterisation laboratories (cardiology IC, neuroradiology IN and radiology IR) and to investigate correlations between occupational lens doses and patient doses. Active electronic personal dosemeters placed over the lead apron were used on a sample of 204 IC procedures, 274 IN and 220 IR (all performed at the same university hospital). Patient dose values (kerma area product) were also recorded to evaluate correlations with occupational doses. Operators used the ceiling-suspended screen in most cases. The median and third quartile values of equivalent dose Hp(10) per procedure measured over the apron for IC, IN and IR resulted, respectively, in 21/67, 19/44 and 24/54 µSv. Patient dose values (median/third quartile) were 75/128, 83/176 and 61/159 Gy cm(2), respectively. The median ratios for dosemeters worn over the apron by operators (protected by the ceiling-suspended screen) and patient doses were 0.36; 0.21 and 0.46 µSv Gy(-1) cm(-2), respectively. With the conservative approach used (lens doses estimated from the over apron chest dosemeter) we came to the conclusion that more than 800 procedures y(-1) and per operator were necessary to reach the new lens dose limit for the three interventional specialties. PMID:25848117

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Tenth ORNL Personnel Dosimetry Intercomparison Study

    SciTech Connect

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

    1985-03-01

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

  6. 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

  7. A comparison of different neutron spectroscopy systems at the reactor facility VENUS

    NASA Astrophysics Data System (ADS)

    Vanhavere, F.; Vermeersch, F.; Chartier, J. L.; Itié, C.; Rosenstock, W.; Köble, T.; d'Errico, F.

    2002-01-01

    The VENUS facility is a zero-power research reactor mainly devoted to studies on LWR fuels. Localised high-neutron rates were found around the reactor, with a neutron/gamma dose equivalent rate ratio as high as three. Therefore, a study of the neutron dosimetry around the reactor was started some years ago. During this study, several methods of neutron spectroscopy were employed and a study of individual and ambient dosemeters was performed. A first spectrometric measurement was done with the IPSN multisphere spectrometer in three positions around the reactor. Secondly, the ROSPEC spectrometer from the Fraunhofer Institut was used. The spectra were also measured with the bubble interactive neutron spectrometer. These measurements were compared with a numerical simulation of the neutron field made with the code TRIPOLI-3. Dosimetric measurements were made with three types of personal neutron dosemeters: an albedo type, a track etch detector and a bubble detector.

  8. A A field test for extremity dose assessment during outages at Korean nuclear power plants.

    PubMed

    Kim, Hee Geun; Kong, Tae Young

    2013-05-01

    During maintenance on the water chamber of a steam generator, the pressuriser heater and the pressure tube feeder in nuclear power plants, workers are likely to receive high radiation doses due to the severe workplace conditions. In particular, it is expected that workers' hands would receive the highest radiation doses because of their contact with the radioactive materials. In this study, field tests for extremity dose assessments in radiation workers undertaking contact tasks with high radiation doses were conducted during outages at pressurised water reactors and pressurised heavy water reactors in Korea. In the test, the radiation workers were required to wear additional thermoluminescent dosemeters (TLDs) on their backs and wrists and an extremity dosemeter on the finger, as well as a main TLD on the chest while performing the maintenance tasks. PMID:23091221

  9. A method to characterise site, urban and regional ambient background radiation.

    PubMed

    Passmore, C; Kirr, M

    2011-03-01

    Control dosemeters are routinely provided to customers to monitor the background radiation so that it can be subtracted from the gross response of the dosemeter to arrive at the occupational dose. Landauer, the largest dosimetry processor in the world with subsidiaries in Australia, Brazil, China, France, Japan, Mexico and the UK, has clients in approximately 130 countries. The Glenwood facility processes over 1.1 million controls per year. This network of clients around the world provides a unique ability to monitor the world's ambient background radiation. Control data can be mined to provide useful historical information regarding ambient background rates and provide a historical baseline for geographical areas. Historical baseline can be used to provide site or region-specific background subtraction values, document the variation in ambient background radiation around a client's site or provide a baseline for measuring the efficiency of clean-up efforts in urban areas after a dirty bomb detonation. PMID:20959341

  10. 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

  11. 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.

  12. 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 165°C, a pre-heating time of 9 s, a heating rate of 25°C s(-1), a reading temperature of 300°C 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

  13. 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)

  14. 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.

  15. Electronic neutron personal dosimetry with superheated drop detectors.

    PubMed

    d'Errico, F; Apfel, R E; Curzio, G; Nath, R

    2001-01-01

    The prototype of an electronic personal neutron dosemeter based on superheated drop detectors is presented. This battery operated device comprises a neutron sensor, bubble-counting electronics and a temperature controller ensuring an optimal dose equivalent response. The neutron sensor is a 12 ml detector vial containing an emulsion of about 50,000 halocarbon-12 droplets of 100 microns diameter. The temperature controller is a low-power, solid-state device stabilising the emulsion at 31.5 degrees C by means of an etched foil heater. The microprocessor controlled counting electronics relies on a double piezo-electric transducer configuration to record bubble formation acoustically via a comparative pulse-shape analysis of ambient noise and detector signals. The performance of the dosemeter was analysed in terms of the requirements presently developed for neutron personal dosemeters. The detection threshold is about 1 microSv, while the personal dose equivalent response to neutrons in the thermal to 62 MeV range falls within a factor 1.6 of 13 bubbles per microSv. PMID:11586744

  16. 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

  17. Single crystal diamond detector for radiotherapy

    NASA Astrophysics Data System (ADS)

    Schirru, F.; Kisielewicz, K.; Nowak, T.; Marczewska, B.

    2010-07-01

    The new generation of synthetic diamonds grown as a CVD single crystal on a high pressure high temperature substrate offers a wide range of applications. In particular, because of the near tissue equivalence and its small size (good spatial resolution), CVD single crystal diamond finds applicability in radiotherapy as a dosemeter of ionizing radiation. In this paper we report the electrical and dosimetric properties of a new diamond detector which was fabricated at IFJ based on a single crystal detector-grade CVD diamond provided with a novel contact metallization. Diamond properties were assessed at IFJ using a Theratron 680E therapeutic 60Co gamma rays unit and at COOK with 6 and 18 MV x-rays Varian Clinac CL2300 C/D accelerator. The new dosemeter showed high electric and dosimetric performances: low value of dark current, high current at the level of some nanoamperes during irradiation, very fast dynamic response with a rise time amounting to parts of a second, good stability and repeatability of the current and linearity of the detector signal at different dose and dose rate levels typically applied in radiotherapy. The results confirm the potential applicability of diamond material as a dosemeter for applications in radiotherapy.

  18. 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.

  19. 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

  20. 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).

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

    NASA Astrophysics Data System (ADS)

    Ávila, O.; Sánchez-Uribe, N. A.; Rodríguez-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 Cancerología" (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 Radiológica", México (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

    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.

  3. 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).

  4. 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

  5. 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-Müller (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

  6. An analysis of the radiation field characteristics for extremity dose assessment during maintenance periods at nuclear power plants in Korea.

    PubMed

    Kim, Hee Geun; Kong, Tae Young

    2012-12-01

    Workers who maintain the water chambers of steam generators during maintenance periods in nuclear power plants (NPPs) have a higher likelihood of high radiation exposure, even if they are exposed for a short period of time. In particular, it is expected that the hands of workers would receive the highest radiation exposure as a consequence of hand contact with radioactive materials. In this study, a characteristic analysis of inhomogeneous radiation fields for contact operations was conducted using thermoluminescent dosemeters for the whole body and extremities during maintenance periods at Korean NPPs. It was observed that inhomogeneous radiation fields for contact operations at NPPs were dominated by high-energy photons. PMID:22628525

  7. Investigation about the thermal features of the ovens used for thermoluminescence

    E-print Network

    Scarpa, G; Moscati, M

    1991-01-01

    The present paper reports the results of an investigation carried out by the PAS-FIBI-DOSIBIO laboratory (ENEA, Casaccia, Roma) about the thermal features of the ovens used for annealing treatments of TL dosemeters. A total number of 45 commercial ovens and muffle furnaces were studied. belonging to 24 Italian Health Physics laboratories. The investigation has shown that the majority of the ovens do not possess a degree of accuracy, stability, uniformity and reproducibility suitable for their use in the field of thermoluminescence dosimetry. Practical suggestions are also given in order to reduce the effects of some of the negative characteristics found in most ovens.

  8. Dose distribution outside the target volume for 170-MeV proton beam.

    PubMed

    Pachnerová Brabcová, K; Ambrožová, I; Kuban?ák, J; Puchalska, M; Vondrá?ek, V; Molokanov, A G; Sihver, L; Davídková, M

    2014-10-01

    Dose delivered outside the proton field during radiotherapy can potentially lead to secondary cancer development. Measurements with a 170-MeV proton beam were performed with passive detectors (track etched detectors and thermoluminescence dosemeters) in three different depths along the Bragg curve. The measurement showed an uneven decrease of the dose outside of the beam field with local enhancements. The major contribution to the delivered dose is due to high-energy protons with linear energy transfer (LET) up to 10 keV µm(-1). However, both measurement and preliminary Monte Carlo calculation also confirmed the presence of particles with higher LET. PMID:24759915

  9. Dosimetry at an interim storage for spent nuclear fuel.

    PubMed

    Králík, M; Kulich, V; Studeny, J; Pokorny, P

    2007-01-01

    The Czech nuclear power plant Dukovany started its operation in 1985. All fuel spent from 1985 up to the end of 2005 is stored at a dry interim storage, which was designed for 60 CASTOR-440/84 casks. Each of these casks can accommodate 84 fuel assemblies from VVER 440 reactors. Neutron-photon mixed fields around the casks were characterized in terms of ambient dose equivalent measured by standard area dosemeters. Except this, neutron spectra were measured by means of a Bonner sphere spectrometer, and the measured spectra were used to derive the corresponding ambient dose equivalent due to neutrons. PMID:17526479

  10. Measurements of the neutron dose and energy spectrum on the International Space Station during expeditions ISS-16 to ISS-21.

    PubMed

    Smith, M B; Akatov, Yu; Andrews, H R; Arkhangelsky, V; Chernykh, I V; Ing, H; Khoshooniy, N; Lewis, B J; Machrafi, R; Nikolaev, I; Romanenko, R Y; Shurshakov, V; Thirsk, R B; Tomi, L

    2013-01-01

    As part of the international Matroshka-R and Radi-N experiments, bubble detectors have been used on board the ISS in order to characterise the neutron dose and the energy spectrum of neutrons. Experiments using bubble dosemeters inside a tissue-equivalent phantom were performed during the ISS-16, ISS-18 and ISS-19 expeditions. During the ISS-20 and ISS-21 missions, the bubble dosemeters were supplemented by a bubble-detector spectrometer, a set of six detectors that was used to determine the neutron energy spectrum at various locations inside the ISS. The temperature-compensated spectrometer set used is the first to be developed specifically for space applications and its development is described in this paper. Results of the dose measurements indicate that the dose received at two different depths inside the phantom is not significantly different, suggesting that bubble detectors worn by a person provide an accurate reading of the dose received inside the body. The energy spectra measured using the spectrometer are in good agreement with previous measurements and do not show a strong dependence on the precise location inside the station. To aid the understanding of the bubble-detector response to charged particles in the space environment, calculations have been performed using a Monte-Carlo code, together with data collected on the ISS. These calculations indicate that charged particles contribute <2% to the bubble count on the ISS, and can therefore be considered as negligible for bubble-detector measurements in space. PMID:22826353

  11. 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.

  12. 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 0.51±0.07 and 0.42±0.04 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

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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,?°) and -Hp(0.07,?°) 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

  18. Neutron measurements in the Vandellňs II nuclear power plant with a Bonner sphere system.

    PubMed

    Fernández, F; Bakali, M; Tomás, M; Muller, H; Pochat, J L

    2004-01-01

    In some Spanish nuclear power plants of pressurised water reactor (PWR) type, albedo thermoluminescence dosemeters are used for personal dosimetry while survey meters, based on a thermal-neutron detector inside a cylindrical or spherical moderator, are used for dose rate assessment in routine monitoring. The response of both systems is highly dependent on the energy of the existing neutron fields. They are usually calibrated by means of ISO neutron sources with energy distributions quite different from those encountered at these installations. Spectrometric measurements with a Bonner sphere system (BSS) allow us to determine the reference dosimetric values. The UAB group, under request from the National Coordinated Research Action, was in charge of characterising the neutron fields and evaluating the response of personal dosemeters at several measurement points inside the containment building of the Catalan Nuclear Power Plant Vandellňs II. The neutron fields were characterised at five places using the UAB-BSS and a home made unfolding code called MITOM. The results obtained confirm the presence of low-energy components in the neutron field in most of the selected points. Moreover, we have found no influence of the nuclear fuel burning on the shape of the spectrum. PMID:15353701

  19. Radon exhalation rate from the soil, sand and brick samples collected from NWFP and FATA, Pakistan.

    PubMed

    Rahman, Said; Mati, N; Matiullah; Ghauri, Badar

    2007-01-01

    In order to characterise the building materials as an indoor radon source, knowledge of the radon exhalation rate from these materials is very important. In this regard, soil, sand and brick samples were collected from different places of the North West Frontier Province (NWFP) and Federally Administered Tribal Areas (FATA), Pakistan. The samples were processed and placed in plastic containers. NRPB radon dosemeters were installed in it at heights of 25 cm above the surface of the samples and containers were then hermetically sealed. After 40-80 d of exposure to radon, CR-39 detectors were removed from the dosemeter holders and etched in 25% NaOH at 80 degrees C for 16 h. From the measured radon concentration values, (222)Rn exhalation rates were determined. Exhalation rate form soil, sand and brick samples was found to vary from 114 +/- 11 to 416 +/- 9 mBq m(-2) h(-1), 205 +/- 16 to 291 +/- 13 mBq m(-2) h(-1) and 245 +/- 12 to 365 +/- 11 mBq m(-2) h(-1), respectively. PMID:17561517

  20. 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

    2015-08-17

    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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. Spectra and Neutron Dosimetry Inside a PET Cyclotron Vault Room

    SciTech Connect

    Vega-Carrillo, Hector Rene; Mendez, Roberto; Iniguez, Maria Pilar; Marti-Climent, Joseph; Penuelas, Ivan; Barquero, Raquel

    2006-09-08

    The neutron field around a PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Pairs of thermoluminescent dosemeters, TLD600 and TLD700, were used as thermal neutron detector inside a Bonner Spheres Spectrometer to measure the neutron spectra at three different positions inside the cyclotron's vault room. Neutron spectra were also determined by Monte Carlo calculations. The hardest spectrum was observed in front of cyclotron target and the softest was noticed at the antipode of target. Neutron doses derived from the measured spectra vary between 11 and 377 mSv/{mu}A-h of proton integrated current, Doses were also measured with a single-moderator remmeter, with an active thermal neutron detector, whose response in affected by the radiation field in the vault room.

  6. 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

  7. 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

  8. Simulation of response functions of fast neutron sensors and development of thin neutron silicon sensor.

    PubMed

    Takada, Masashi; Nakamura, Takashi; Matsuda, Mikihiko; Nunomiya, Tomoya

    2014-10-01

    On radiation detection using silicon sensor, signals are produced from collected charges in a depletion layer; however, for high-energy particles, this depletion layer is extended due to funnelling phenomenon. The lengths of charge collection were experimentally obtained from proton peak energies in measured pulse-heights. The length is extended with increasing proton energy of up to 6 MeV, and then, is constant over 6 MeV. The response functions of fast neutron sensors were simulated for 5- and 15-MeV monoenergetic and (252)Cf neutron sources using the Monte Carlo N-Particle eXtended code. The simulation results agree well with the experimental ones, including the effect of funnelling phenomenon. In addition, a thin silicon sensor was developed for a new real-time personal neutron dosemeter. Photon sensitivity is vanishingly smaller than neutron one by a factor of 5×10(-4). PMID:24516186

  9. Measurements of gamma dose and thermal neutron fluence in phantoms exposed to a BNCT epithermal beam with TLD-700.

    PubMed

    Gambarini, G; Magni, D; Regazzoni, V; Borroni, M; Carrara, M; Pignoli, E; Burian, J; Marek, M; Klupak, V; Viererbl, L

    2014-10-01

    Gamma dose and thermal neutron fluence in a phantom exposed to an epithermal neutron beam for boron neutron capture therapy (BNCT) can be measured by means of a single thermoluminescence dosemeter (TLD-700). The method exploits the shape of the glow curve (GC) and requires the gamma-calibration GC (to obtain gamma dose) and the thermal-neutron-calibration GC (to obtain neutron fluence). The method is applicable for BNCT dosimetry in case of epithermal neutron beams from a reactor because, in most irradiation configurations, thermal neutrons give a not negligible contribution to the TLD-700 GC. The thermal neutron calibration is not simple, because of the impossibility of having thermal neutron fields without gamma contamination, but a calibration method is here proposed, strictly bound to the method itself of dose separation. PMID:24435913

  10. Simulated workplace neutron fields

    NASA Astrophysics Data System (ADS)

    Lacoste, V.; Taylor, G.; Röttger, 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.

  11. Neutron Dose measurement in the carbon ion therapy area at HIRFL (IMP) as 12C ions with energies from 165 to 350MeV/u

    E-print Network

    Xu, Jun-Kui; Yan, Wei-Wei; Su, You-Wu; Li, Zong-Qiang; Wang, Mao; Pang, Cheng-Guo; Xu, Chong

    2016-01-01

    The neutron dose distributions on observation distances and on observation angles were measured using a Wendi-II neutron dose-meter at the deep tumor therapy terminal at HIRFL (Heavy Ion Research Facility in Lanzhou) as 12C ions with energies from 165 to 350 MeV/u bombarding on thick solid water targets with different thickness according to the ion energies. The experimental results were compared with those calculated by FLUKA code. It is found that the experimental data was in good agreement with the calculated results. The neutron energy spectra were also studied by using the FLUKA code. The results are valuable for the shielding design of high energy heavy ion medical machines and for the individual dose assessment.

  12. 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

  13. Radionuclide neutron sources in calibration laboratory--neutron and gamma doses and their changes in time.

    PubMed

    Józefowicz, K; Golnik, N; Tulik, P; Zielczynski, M

    2007-01-01

    The calibration laboratory, having standard neutron fields of radionuclide sources, should perform regular measurements of fields' parameters in order to check their stability and to get knowledge of any changes. Usually, accompanying gamma radiation is not of serious concern, but some personal dosemeters, old neutron dose equivalent meters with scintillation detectors and the dose meters of mixed radiation require the determination of this component. In the Laboratory of Radiation Protection Measurements in the Institute of Atomic Energy, Poland, the fields of radionuclide neutron sources (252)Cf, (241)Am-Be and (239)Pu-Be were examined for nearly 20 y. A number of detectors and methods have been applied for the determination of neutron ambient dose equivalent rate and for the determination of neutron and gamma dose components. This paper presents the recent results of measurements of gamma and neutron dose and dose equivalent, compared with the results accumulated in nearly 20 y. PMID:17513855

  14. Dose evaluation in criticality accident conditions using transient critical facilities fueled with a fissile solution.

    PubMed

    Nakamura, T; Tonoike, K; Miyoshi, Y

    2004-01-01

    Neutron dose measurement and evaluation techniques in criticality accident conditions using a thermo luminescence dosemeter (TLD) was studied at the Transient Experiment Critical Facility (TRACY) of Japan Atomic Energy Research Institute (JAERI). In the present approach, the absorbed dose is derived from the ambient dose equivalent measured with a TLD, using the appropriate conversion factor given by computation. Using this technique, the neutron dose around the SILENE reactor of the Institute for Radioprotection and Nuclear Safety (IRSN) of France was measured in the Accident Dosimetry Intercomparison Exercise (June 10-21, 2002) organized by OECD/NEA and IRSN. In this exercise, the gamma dose was also measured with a TLD. In this report, measurements and evaluation results at TRACY and SILENE are presented. PMID:15353695

  15. Recalibration of indium foil for personnel screening in criticality accidents.

    PubMed

    Takada, C; Tsujimura, N; Mikami, S

    2011-03-01

    At the Nuclear Fuel Cycle Engineering Laboratories of the Japan Atomic Energy Agency (JAEA), small pieces of indium foil incorporated into personal dosemeters have been used for personnel screening in criticality accidents. Irradiation tests of the badges were performed using the SILENE reactor to verify the calibration of the indium activation that had been made in the 1980s and to recalibrate them for simulated criticalities that would be the most likely to occur in the solution process line. In addition, Monte Carlo calculations of the indium activation using the badge model were also made to complement the spectral dependence. The results lead to a screening level of 15 kcpm being determined that corresponds to a total dose of 0.25 Gy, which is also applicable in posterior-anterior exposure. The recalibration based on the latest study will provide a sounder basis for the screening procedure in the event of a criticality accident. PMID:21062798

  16. 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

  17. 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

  18. Thermal neutron calibration channel at LNMRI/IRD.

    PubMed

    Astuto, A; Salgado, A P; Leite, S P; Patrăo, 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

  19. 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 ?-rays from natural radionuclides in the sediment. PMID:25944958

  20. Evaluation of an automated FDG dose infuser to PET-CT patients.

    PubMed

    Sánchez, Roberto M; Vano, Eliseo; Fernández, Jose M; Ginjaume, Mercč; Carreras, José L

    2015-07-01

    An experience with an automated infuser device at a university hospital is presented in this paper. Occupational doses at operators' fingertips were measured using optically stimulated luminescence dosemeters for two different scenarios: (i) using a semi-automatic system to prepare the fluorodesoxiglucose (FDG) injections that were delivered to the patient manually and (ii) using an automated infusion device that prepares and delivers the FDG dose. The accuracy of the activity prepared by the automatic system was also verified. Reductions in fingertip doses of 60 % using the fully automatic system have been measured. The difference between the programmed and the delivered activity was 2 %. The use of the automatic infuser in the authors' institution has led to a substantial reduction in hand radiation doses. But contamination risks, even though reduced, still exist; therefore, radioisotope manipulation should follow strict radiation protection rules to avoid incidents. Improved accuracy in dose delivery reduces chances of dose misadministration. PMID:25821215

  1. 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; Sánchez-Casanueva, R; Vano, E; Fernández, J M; Álvarez, F J; Ramos, J; Martínez, G; López-Mínguez, 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.; Rühm, 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.

  12. Intercomparison of Monte Carlo radiation transport codes to model TEPC response in low-energy neutron and gamma-ray fields.

    PubMed

    Ali, F; Waker, A J; Waller, E J

    2014-10-01

    Tissue-equivalent proportional counters (TEPC) can potentially be used as a portable and personal dosemeter in mixed neutron and gamma-ray fields, but what hinders this use is their typically large physical size. To formulate compact TEPC designs, the use of a Monte Carlo transport code is necessary to predict the performance of compact designs in these fields. To perform this modelling, three candidate codes were assessed: MCNPX 2.7.E, FLUKA 2011.2 and PHITS 2.24. In each code, benchmark simulations were performed involving the irradiation of a 5-in. TEPC with monoenergetic neutron fields and a 4-in. wall-less TEPC with monoenergetic gamma-ray fields. The frequency and dose mean lineal energies and dose distributions calculated from each code were compared with experimentally determined data. For the neutron benchmark simulations, PHITS produces data closest to the experimental values and for the gamma-ray benchmark simulations, FLUKA yields data closest to the experimentally determined quantities. PMID:24162375

  13. 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

  14. 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

  15. 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

  16. 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

  17. Shielding evaluation of a medical linear accelerator vault in preparation for installing a high-dose rate 252Cf remote afterloader.

    PubMed

    Melhus, C S; Rivard, M J; Kurkomelis, J; Liddle, C B; Massé, F X

    2005-01-01

    In support of the effort to begin high-dose rate 252Cf brachytherapy treatments at Tufts-New England Medical Center, the shielding capabilities of a clinical accelerator vault against the neutron and photon emissions from a 1.124 mg 252Cf source were examined. Outside the clinical accelerator vault, the fast neutron dose equivalent rate was below the lower limit of detection of a CR-39 etched track detector and below 0.14 +/- 0.02 muSv h(-1) with a proportional counter, which is consistent, within the uncertainties, with natural background. The photon dose equivalent rate was also measured to be below background levels (0.1 muSv h(-1)) using an ionisation chamber and an optically stimulated luminescence dosemeter. A Monte Carlo simulation of neutron transport through the accelerator vault was performed to validate measured values and determine the thermal-energy to low-energy neutron component. Monte Carlo results showed that the dose equivalent rate from fast neutrons was reduced by a factor of 100,000 after attenuation through the vault wall, and the thermal-energy neutron dose equivalent rate would be an additional factor of 1000 below that of the fast neutrons. Based on these findings, the shielding installed in this facility is sufficient for the use of at least 5.0 mg of 252Cf. PMID:15755770

  18. Uncertainties in workplace external dosimetry--an analytical approach.

    PubMed

    Ambrosi, P

    2006-01-01

    The uncertainties associated with external dosimetry measurements at workplaces depend on the type of dosemeter used together with its performance characteristics and the information available on the measurement conditions. Performance characteristics were determined in the course of a type test and information about the measurement conditions can either be general, e.g. 'research' and 'medicine', or specific, e.g. 'X-ray testing equipment for aluminium wheel rims'. This paper explains an analytical approach to determine the measurement uncertainty. It is based on the Draft IEC Technical Report IEC 62461 Radiation Protection Instrumentation-Determination of Uncertainty in Measurement. Both this paper and the report cannot eliminate the fact that the determination of the uncertainty requires a larger effort than performing the measurement itself. As a counterbalance, the process of determining the uncertainty results not only in a numerical value of the uncertainty but also produces the best estimate of the quantity to be measured, which may differ from the indication of the instrument. Thus it also improves the result of the measurement. PMID:17065194

  19. 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 ?Sv/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.

  20. Dosimetric monitoring in Ukraine--present status and path to the future.

    PubMed

    Chumak, V; Boguslavskaya, A

    2007-01-01

    Despite wide use of nuclear energy and radiation sources in industry and medicine, there is no centralised dose accounting system in Ukraine; existing dosimetry services operate obsolete manual thermoluminescence dosemeter (TLD) readers and do not meet modern proficiency standards. Currently, dosimetric monitoring is required for approximately 42,000 occupationally exposed workers, including 9100 in medicine, 17,000 employees of nuclear power plants and approximately 16,000 workers dealing with other sources of occupational exposure. This article presents the plan of elaboration of the United System for monitoring and registration of individual doses which has the aim of harmonisation of individual monitoring in Ukraine through securing methodical unity; scientific and methodological guidance of individual dosimetric control; procurement of common technical policy regarding nomenclature and operation of instrumentation; implementation of quality assurance programmes; development and support of information infrastructure, in particular operation of the national registry of individual doses; training and certification of personnel engaged in the system of individual dosimetric monitoring. PMID:16987910

  1. Workplace monitoring for exposures to radon and to other natural sources in Europe: integration of monitoring for internal and external exposures.

    PubMed

    Lopez, M A; Currivan, L; Falk, R; Olko, P; Wernli, C; Castellani, C M

    2004-01-01

    Part of the action of the EURADOS working group (European Radiation Dosimetry Group) on "Harmonisation of Individual Monitoring in Europe" was to investigate how the results from personal dosemeters for external radiation, from monitoring for internal exposure and from workplace monitoring, can be combined into a complete and consistent system of individual monitoring. To facilitate this work, the "EURADOS questionnaire Q3" relating to radon and other natural sources of radiation in the workplace was distributed to relevant institutes across Europe. A total of 24 countries replied to the questionnaire. This study offers an important overview on actual regulations, national standards and reference levels for protection of employees from radon and other natural sources in different workplace scenarios. Information was also collected on individual monitoring and area monitoring to determine individual doses in workplaces with elevated levels of natural radiation. The article discusses in detail the results obtained showing by country the reference level in workplaces for radon gas and other natural sources. In both instances, exposures in mines, other underground workplaces, industry workplaces/waterworks, offices, schools and day-care homes were considered. The resultant data clearly indicate that there is a need for harmonisation among countries, not least in the areas of regulation and use of reference levels in the workplace. PMID:15574988

  2. Gafchromic film as a fast visual indicator of radiation exposure of first responders.

    PubMed

    Oren, Unal; Rääf, Christopher L; Mattsson, Sören

    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

  3. 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

  4. 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

  5. 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.

  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. Evaluation of treatment planning system of brachytherapy according to dose to the rectum delivered.

    PubMed

    Allahverdi, Mahmoud; Sarkhosh, Mina; Aghili, Mahdi; Jaberi, Ramin; Adelnia, Akbar; Geraily, Ghazale

    2012-07-01

    The aim of this study was to assess the actual dose delivered to the rectum and compare it with the treatment planning system (TPS) reports. In this study, the dose delivered to the rectum was measured by semiconductor diode detectors (PTW, Germany). The factors that influence diode response were investigated as well. Calibration factors of diodes were measured weekly to investigate the effect of time interval on the accuracy of calibration. Then 40 applications of patients with cervix carcinoma were evaluated. Rectum dose was measured by means of rectal dosemeter and compared with the TPS-calculated dose. In this research, the differences between the measured and the calculated dose were investigated. The mean difference between the TPS-calculated dose and the measured dose was 6.5% (range: -22 to +39) for rectum. The TPS-calculated maximum dose was typically higher than the measured maximum dose. The study showed that the main reason for the difference was due to the movements of the patient and applicator shift in the elapsed time between the imaging and treatment stage. It is recommended that in vivo dosimetry should be performed in addition to treatment planning computation. In vivo dosimetry is a reliable solution to compare the planned and actual dose delivered to organs at risk. PMID:22128355

  8. The Use of a Gamma Ray Imaging Device for In-Cell Assay

    SciTech Connect

    Hughes, K.; Walker, S.

    2008-07-01

    Gamma ray imaging has become an established technique within the nuclear industry, especially within the field of decommissioning. The technique is most commonly used to identify the origins of radiation within contaminated environments in order to provide a level of characterisation that is not possible using conventional dosemeters. Gamma ray images demonstrate, in a clear, easy to understand format, where there are significant sources of gamma emitting radiation. These images are often used to help determine decontamination, decommissioning or clean-up strategies. Recent developments at Sellafield, in the UK, have demonstrated how gamma ray imaging devices can be used to perform in-cell, quantitative, assay. A data collection and analysis procedure has been developed that can be used to produce activity values for gamma bearing items. The technique is of especial value as the items of interest can be located in cells with limited or no man access, either due to poor physical access or high dose rates. This quantitative assay technique can be used to segregate wastes in-situ, allowing only wastes meeting user-specified criteria to be selected. This paper describes two successful applications of this newly developed technique on the Sellafield site. The technique is covered by European Patent - EP1315004A1 and US Patent - US7095030B2. (authors)

  9. 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

  10. 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

  11. 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.

  12. Dosimetric feature of natural biotite mineral.

    PubMed

    Kalita, J M; Wary, G

    2015-04-01

    A thermoluminescence (TL) study relevant to radiation dosimetry has been carried out for X-ray irradiated biotite mineral under un-annealed and different annealed (473, 573, 673 and 773 K) conditions. Some significant variations in dosimetric characteristics have been observed with annealing treatment. Due to generation of an additional shallow trap level at depth 0.78 eV in 673 and 773 K annealed samples, the dose response is found to improve. For the 773 K annealed sample, a linear dose response has been observed from 10 to 1100 mGy. The fading is ?13% within 5 d after irradiation and onward it reduces to 7% up to 60 d. Reproducibility of this (773 K) sample is excellent. After 10 recycles the coefficient of variations in the results for the 60, 180 and 1000 mGy dose-irradiated samples are found to be 0.97, 1.31 and 1.03%, respectively. The potential use of biotite as a natural X-ray dosemeter is discussed. PMID:25227440

  13. 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

  14. Preparation and thermoluminescence properties of aluminium oxide doped with europium.

    PubMed

    Azorín, J; Esparza, A; Falcony, C; Rivera, T; García, M; Martínez, E

    2002-01-01

    There is little information concerning the use of rare earths as dopants of Al2O3. This paper presents the preparation method and the results of studying the thermoluminescence characteristics of Al2O3:Eu exposed to ultraviolet light. Phosphor powder was obtained by the evaporation method. Optimum dopant concentration was 10% at an evaporation temperature of 700 degrees C. The powder obtained was submitted to thermal treatments at high temperatures in order to stabilise the traps. Diffraction patterns showed amorphous powder up to 500 degrees C; as the temperature was raised crystalline phases of Al2O3 appeared. The photoluminescence spectrum induced by 250 nm UV light exhibited four well defined peaks characteristic of the Eu3+ ion. The glow curve exhibited two peaks at 180 and 350 degrees C. The sensitivity of Al2O3:Eu was 10 times lower than Al2O3:C. The thermoluminescence response was linear from 2.4 to 3000 microJ.cm(-2) of spectral irradiance, and the fading 2% in a month. From these results it can be concluded that Al2O3:Eu has potential as an UV dosemeter. PMID:12382877

  15. 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

  16. 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

  17. Radioactivity concentrations and dose assessment for soil samples around nuclear power plant IV in Taiwan.

    PubMed

    Tsai, Tsuey-Lin; Lin, Chun-Chih; Wang, Tzu-Wen; Chu, Tieh-Chi

    2008-09-01

    Activity concentrations and distributions of natural and man-made radionuclides in soil samples collected around nuclear power plant IV, Taiwan, were investigated for five years to assess the environmental radioactivity and characterisation of radiological hazard prior to commercial operation. The activity concentrations of radionuclides were determined via gamma-ray spectrometry using an HPGe detector. Data obtained show that the average concentrations of the (238)U and (232)Th series, and (40)K, were within world median ranges in the UNSCEAR report. The (137)Cs ranged from 2.46 +/- 0.55 to 12.13 +/- 1.31 Bq kg(-1). The terrestrial absorbed dose rate estimated by soil activity and directly measured with a thermoluminescence dosemeter (excluding cosmic rays), and the annual effective doses, were 45.63, 57.34 nGy h(-1) and 57.19 microSv, respectively. Experimental results were compared with international recommended values. Since the soil in this area is an important building material, the mean radium equivalent activity, external and inhalation hazard indices and the representative level index using various models given in the literature for the study area were 98.18 Bq kg(-1), 0.27, 0.34 and 0.73, respectively, which were below the recommended limits. Analytical results demonstrate that no radiological anomaly exists. The baseline data will prove useful and important in estimating the collective dose near the new nuclear power plant under construction in Taiwan. PMID:18714131

  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 µGy, 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. 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 µGy 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

  20. The MATROSHKA Facility - History and science overview

    NASA Astrophysics Data System (ADS)

    Reitz, G.; Berger, T.

    The ESA MATROSHKA facility was realized through the German Aerospace Center DLR Cologne as main contractor On the 29th of January 2004 the facility was launched with a Russian PROGRESS vehicle to the International Space Station It was installed outside the Russian segment Zvezda on the 26th February 2004 and remained there until August 2005 and simulates as exact as possible an astronaut during an extravehicular activity EVA The MATROSHKA facility basically consists of a human phantom a Base Structure and a Container The container as well as the phantom is mounted to the base structure which serves as a footprint for the human phantom The container is a Carbon Fiber structure and forms with the Base Structure a closed volume that contains a dry oxygen atmosphere and protects the phantom against e g space vacuum space debris solar UV and material off-gassing It acts also as a simulation of the space suit The phantom body is made of commercial phantom parts well introduced in the field of radiotherapy It consists of 33 slices composed of natural bones embedded in tissue equivalent plastic of different density for tissue and lung The Phantom slices are equipped with channels and cut-outs to allow the accommodation of active and passive dosemeters temperature and pressure sensors The radiation experiments accommodated in the facility are performed under leadership of DLR in a cooperation of more than 15 research institutes from all over the world The MATROSHKA experiments represent therefore the currently biggest international

  1. 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

  2. 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

  3. 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

  4. 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 30×30×15 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

  5. 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

  6. 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

  7. An investigation of the radiation doses to the lower legs and feet of staff undertaking interventional procedures

    PubMed Central

    Artschan, R E R; Chase, K; Fender, A; Howells, P G; Buchan, S

    2014-01-01

    Objective: Occupational radiation doses from fluoroscopic procedures are some of the highest doses of exposure amongst medical staff using radiography. Protective equipment and dose monitoring are used to minimize and control the risk from these occupational doses. Other studies have considered the effectiveness of this protection, but this study further considers whether protection is adequate for the lower leg and foot and the extent to which these doses can be reduced. Methods: Scatter air kerma profiles at toe level were measured with an ionization chamber. Thermoluminescent dosemeters and lower extremity phantoms were used to estimate the dose variation with the height of patient couch. A 7-week period of in situ toe dose monitoring of four radiologists was also undertaken. Results: The use of protective curtains effectively reduced the exposure to most of the lower extremities. Toe doses were found to be high and increased with increase in couch height. In situ monitoring indicated annual toe doses of 110?mSv for two of the four radiologists monitored. Conclusion: Protective curtains should be used, but they might have limitations with respect to toe doses. Annual toe doses approaching the classification threshold of 150?mSv were measured for two radiologists. Caution should be exercised when there is a gap below curtains and, when possible, staff should step back from the couch. Lower legs and toes should be included in local radiation protection programmes. Advances in knowledge: Toe doses in interventional radiology may be higher than expected and may have to be included in radiation protection programmes. PMID:24678856

  8. Observation of Radiation Environment on ISS during Solar Particle Event in March 2012

    NASA Astrophysics Data System (ADS)

    Semkova, Jordanka; Dachev, Tsvetan; Koleva, Rositza; Maltchev, Stephan; Bankov, Nikolay; Benghin, Victor; Shurshakov, Vyacheslav; Petrov, Vladislav; Drobyshev, Sergey

    2013-04-01

    The Liulin-5 charged particle telescope observes the radiation conditions in the spherical tissue-equivalent phantom of MATROSHKA-R international project on the International Space Station (ISS) since June 2007. In this paper attention is drawn to the results from measurements of the radiation parameters during the Solar Particle Event (SPE) occurred 7-8.03.2012. During that SPE the solar particles penetrated the ISS orbit at high geographic latitudes in the regions of the south and north Earth magnetic poles and at 3< L they caused particle flux and dose rates increase in all three detectors of Liulin-5, located at 40, 60 and 165 mm depths along the phantom's radius. The maximum flux at 40 mm depth observed outside the inner radiation belt in the region of South Atlantic Anomaly (SAA) during that SPE reached 7.2 part/cm2.s and the dose rate reached 107.8 µGy/hour. The total dose outside SAA received during the SPE was 259.9 µGy. Compared are the dose rates, particle fluxes, deposited energy spectra, linear energy transfer spectra, obtained radiation quality factors and dose equivalent values during the SPE and during quite conditions. Compared are data from Liulin-5 charged particle telescope and from other particle and radiation detectors in space during that SPE. Compared are the results from radiation measurements on ISS during SPE of March 2012 and data from SPE radiation environment investigations on Mir manned space station in 1989-1993 time periods, conducted with Liulin type dosemeters.

  9. An engagement factor for caregiver radiation dose assessment with radioiodine treatment.

    PubMed

    Lee, Hyun Kuk; Hong, Seong Jong; Jeong, Kyu Hwan; Jung, Jae Won; Kim, Seong Min; Kang, Yun-Hee; Han, Man Seok

    2015-03-01

    This study aims to suggest ways to better manage thyroid cancer patients treated with high- and low-activity radioiodine ((131)I) by assessing external radiation doses to family members and caregivers and the level of radiation in the surrounding environment. The radiation doses to caregivers of 33 inpatients (who were quarantined in the hospital for 2-3 d after treatment) and 31 outpatients who received radioiodine treatment after thyroidectomy were measured using passive thermoluminescence dosemeters. In this study, 33 inpatients were administered high-activity (100-200 mCi) (131)I, and 31 outpatients were administered low-activity (30 mCi) (131)I. The average doses to caregivers were measured at 0.61 mSv for outpatients and 0.16 mSv for inpatients. The total integrated dose of the recovery (recuperation) rooms where the patients stayed after release from hospital was measured to be 0.83 mSv for outpatients and 0.23 mSv for inpatients. To reflect the degree of engagement between the caregiver and the patient, considering the duration and distance between two during exposure, the authors used the engagement factor introduced by Jeong et al. (Estimation of external radiation dose to caregivers of patients treated with radioiodine after thyroidectomy. Health Phys 2014; 106: :466-474.). This study presents a new engagement factor (K-value) of 0.82 obtained from the radiation doses to caregivers of both in- and out-patients treated with high- and low-activity radioiodine, and based on this new value, this study presented a new predicted dose for caregivers. A patient treated with high-activity radioiodine can be released after 24 h of isolation, whereas outpatients treated with low-activity radioiodine should be isolated for at least 12 h. PMID:25028695

  10. 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

  11. 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.

  12. 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)

    Muńoz, 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.

  13. Validation of a Monte Carlo simulation for dose assessment in dental cone beam CT examinations.

    PubMed

    Morant, J J; Salvadó, M; Casanovas, R; Hernández-Girón, I; Velasco, E; Calzado, A

    2012-07-01

    A Monte Carlo (MC) simulation for calculating absorbed dose has been developed and applied for dental applications with an i-CAT cone beam CT (CBCT) system. To validate the method a comparison was made between calculated and measured dose values for two different clinical protocols. Measurements with a pencil CT chamber were performed free-in-air and in a CT dose head phantom; measurements were also performed with a transmission ionization chamber. In addition for each protocol a total number of 58 thermoluminescence dosemeters (TLD) were packed in groups and placed at 16 representative anatomical locations of an anthropomorphic phantom (Remab system) to assess absorbed doses. To simulate X-ray exposure, a software application based on the EGS4 package was applied. Dose quantities were calculated for different voxelized models representing the CT ionization and transmission chambers, the TLDs, and the phantoms as well. The dose quantities evaluated in the comparison were the accumulated dose averaged along the rotation axis (D(i)), the volume average dose,D(vol) for the dosimetric phantom, the dose area product (DAP) and the absorbed dose for the TLDs. Absolute differences between measured and simulated outcomes were ? 2.1% for free-in-air doses; ? 6.2% in the 5 cavities of the CT dose head phantom; ? 13% for TLDs inside the primary beam. Such differences were considered acceptable in all cases and confirmed the validity of the MC program for different geometries. In conclusion, the devised MC simulation program can be a robust tool to optimize protocols and estimate patient doses for CBCT units in dental, oral and maxillofacial radiology. PMID:21807542

  14. Environmental gamma dosimetry with OSL of alpha-Al(2)O(3):C for in situ sediment measurements.

    PubMed

    Richter, D; Dombrowski, H; Neumaier, S; Guibert, P; Zink, A C

    2010-09-01

    The physical properties of alpha-Al(2)O(3):C are very similar to that of quartz, which make it an attractive dosimetric material for geological and archaeological dating applications. Storage experiments in an ultra-low-radiation underground environment (UDO at PTB) and gamma-ray spectrometry show that the optically stimulated luminescence (OSL) signal of this material does neither suffer from a significant inherent background caused by traces of radionuclides (<6 microGy a(-1)) nor from fading. After having performed a simple calibration procedure, gamma dosimetry based on alpha-Al(2)O(3):C detectors, which were exposed in a brick block and a lead castle for different periods of time, provided concordant results with dose values derived from independent gamma-ray spectrometric measurements using high-purity germanium and NaI:Tl detectors. These investigations indirectly confirm both the absence of a significant inherent background and fading of the detector material. Small doses of a few micro gray accumulated in short exposure times to environmental radiation can be accurately measured, even when doses (i.e. transport dose) much larger than the actual environmental dose have to be subtracted. It is shown that the OSL signal caused by small transport doses can be easily and reproducibly reset even under difficult field conditions by illuminating the dosemeters with the blue light from Luxeon LEDs. Summarised, alpha-Al(2)O(3):C appears to be the material of choice for dosimetric dating applications of quartz or related materials, when analysed by using OSL. PMID:20534630

  15. 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 µSv, and the minimum and maximum values recorded were 1 and 41 µSy, 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

  16. 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; Körner, Christine; Olko, Pawel; Shurshakov, Vyacheslav; Reitz, Günther

    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

  17. 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.

  18. 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.

  19. Improving IMRT quality control efficiency using an amorphous silicon electronic portal imager.

    PubMed

    Budgell, G J; Zhang, Q; Trouncer, R J; Mackay, R I

    2005-11-01

    An amorphous silicon electronic portal imaging device (EPID) has been investigated to determine its usefulness and efficiency for performing linear accelerator quality control checks specific to step and shoot intensity modulated radiation therapy (IMRT). Several dosimetric parameters were measured using the EPID: dose linearity and segment to segment reproducibility of low dose segments, and delivery accuracy of fractions of monitor units. Results were compared to ion chamber measurements. Low dose beam flatness and symmetry were tested by overlaying low dose beam profiles onto the profile from a stable high-dose exposure and visually checking for differences. Beam flatness and symmetry were also calculated and plotted against dose. Start-up reproducibility was tested by overlaying profiles from twenty successive two monitor unit segments. A method for checking the MLC leaf calibration was also tested, designed to be used on a daily or weekly basis, which consisted of summing the images from a series of matched fields. Daily images were coregistered with, then subtracted from, a reference image. A threshold image showing dose differences corresponding to > 0.5 mm positional errors was generated and the number of pixels with such dose differences used as numerical parameter to which a tolerance can be applied. The EPID was found to be a sensitive relative dosemeter, able to resolve dose differences of 0.01 cGy. However, at low absolute doses a reproducible dosimetric nonlinearity of up to 7% due to image lag/ghosting effects was measured. It was concluded that although the EPID is suitable to measure segment to segment reproducibility and fractional monitor unit delivery accuracy, it is still less useful than an ion chamber as a tool for dosimetric checks. The symmetry/flatness test proved to be an efficient method of checking low dose profiles, much faster than any of the alternative methods. The MLC test was found to be extremely sensitive to sudden changes in MLC calibration but works best with a composite reference image consisting of an average of five successive days' images. When used in this way it proved an effective and efficient daily check of MLC calibration. Overall, the amorphous silicon EPID was found to be a suitable device for IMRT QC although it is not recommended for dosimetric tests. Automatic procedures for low monitor unit profile analysis and MLC leaf positioning yield considerable time-savings over traditional film techniques. PMID:16370416

  20. Improving IMRT quality control efficiency using an amorphous silicon electronic portal imager

    SciTech Connect

    Budgell, G.J.; Zhang, Q.; Trouncer, R.J.; Mackay, R.I.

    2005-11-15

    An amorphous silicon electronic portal imaging device (EPID) has been investigated to determine its usefulness and efficiency for performing linear accelerator quality control checks specific to step and shoot intensity modulated radiation therapy (IMRT). Several dosimetric parameters were measured using the EPID: dose linearity and segment to segment reproducibility of low dose segments, and delivery accuracy of fractions of monitor units. Results were compared to ion chamber measurements. Low dose beam flatness and symmetry were tested by overlaying low dose beam profiles onto the profile from a stable high-dose exposure and visually checking for differences. Beam flatness and symmetry were also calculated and plotted against dose. Start-up reproducibility was tested by overlaying profiles from twenty successive two monitor unit segments. A method for checking the MLC leaf calibration was also tested, designed to be used on a daily or weekly basis, which consisted of summing the images from a series of matched fields. Daily images were co-registered with, then subtracted from, a reference image. A threshold image showing dose differences corresponding to >0.5 mm positional errors was generated and the number of pixels with such dose differences used as numerical parameter to which a tolerance can be applied. The EPID was found to be a sensitive relative dosemeter, able to resolve dose differences of 0.01 cGy. However, at low absolute doses a reproducible dosimetric nonlinearity of up to 7% due to image lag/ghosting effects was measured. It was concluded that although the EPID is suitable to measure segment to segment reproducibility and fractional monitor unit delivery accuracy, it is still less useful than an ion chamber as a tool for dosimetric checks. The symmetry/flatness test proved to be an efficient method of checking low dose profiles, much faster than any of the alternative methods. The MLC test was found to be extremely sensitive to sudden changes in MLC calibration but works best with a composite reference image consisting of an average of five successive days' images. When used in this way it proved an effective and efficient daily check of MLC calibration. Overall, the amorphous silicon EPID was found to be a suitable device for IMRT QC although it is not recommended for dosimetric tests. Automatic procedures for low monitor unit profile analysis and MLC leaf positioning yield considerable time-savings over traditional film techniques.