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1

Personal photon dosemeter trial--Devonport Royal Dockyard.  

PubMed

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

Collison, Roger

2005-03-01

2

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

SciTech Connect

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.

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

1985-06-01

3

State of the Art in Electronic Dosemeters for Neutrons  

SciTech Connect

The paper presents an overview of electronic personal dosemeters for neutrons in mixed neutron/photon fields. The energy response of commercially available electronic dosemeters in quasi-monoenergetic neutron fields and their performance in working places is discussed. The response curves are extended to high-energy neutrons up to 100 MeV, new prototype dosemeters are described and discussed especially for use at high-energy accelerators and in space.

Luszik-Bhadra, Marlies [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany)

2011-05-05

4

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

SciTech Connect

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.

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

1992-01-01

5

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

SciTech Connect

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.

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

1992-08-01

6

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

PubMed

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

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

2004-01-01

7

A STUDY OF THE IRRADIATION TEMPERATURE COEFFICIENT FOR L-ALANINE AND DL-ALANINE DOSEMETERS  

E-print Network

of the parameters that influence the dosemeter response. The temperature of the dosemeter during irradiation-controlled irradiations; and com- putations from limited data. One influence not explored was the isomeric composition out at CIAE. (The mention of commercial products throughout this paper does not imply recommen- dation

8

Experience on evaluation of passive neutron dosemeters according to ISO 21909.  

PubMed

This paper presents experience, found problems and lessons learnt during the evaluations of various TLD and CR-39 passive neutron dosemeters according to ISO 21909. Recommendations for the standard, being currently in revision, are also discussed. PMID:24287599

Voytchev, M

2014-10-01

9

1983 ORNL intercomparison of personnel neutron and gamma dosemeters  

SciTech Connect

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.

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

1985-01-01

10

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

PubMed

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

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

2014-10-01

11

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

PubMed

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

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

2004-01-01

12

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

PubMed

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

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

2004-01-01

13

PTB intercomparisons of passive H*(10) area dosemeters for environmental monitoring.  

PubMed

For measuring the quantity ambient dose equivalent, H*(10), various passive photon and neutron dosemeters have been newly developed and are used in particular for the monitoring of nuclear facilities in the radiation field of the natural ambient radiation. Since 2005, the Physikalisch-Technische Bundesanstalt (PTB) has been performing intercomparisons to study fundamental properties and the long-term behaviour of area dosemeters under real environmental conditions, i.e. the accuracy of photon and neutron measurements performed in the complex natural radiation field. Measuring bodies from four European countries were the participants, including Germany. The goal was, on the one hand, quality assurance for existing passive dosemeters and measurement procedures and, on the other hand, the experimental investigation of whether the requirements of the appropriate standards and guidelines are met in practical use. PMID:24051174

Dombrowski, H; Neumaier, S

2014-10-01

14

Calibration of personal dosemeters in terms of the ICRU operational quantities  

SciTech Connect

The International Commission on Radiological Units and Measurements (ICRU) has defined several new operational quantities for radiation protection purposes. The quantities to be used for personal monitoring are defined at depths in the human body. Because these quantities are impossible to measure directly, the ICRU has recommended that personal dosemeters should be calibrated under simplified conditions on an appropriate phantom, such as the ICRU sphere. The US personal dosimetry accreditation programs make use of a 30 {times} 30 {times} 15 cm polymethymethacrylate (PMMA) phantom, therefore it is necessary to relate the response of dosemeters calibrated on this phantom to the ICRU operational quantities. Calculations of the conversion factors to compute dosemeter response in terms of the operational quantities have been performed using the code MCNP. These calculations have also been compared to experimental measurements using thermoluminescent (TLD) detectors.

McDonald, J.C. [Pacific Northwest Lab., Richland, WA (United States); Hertel, N.E. [Texas Univ., Austin, TX (United States). Dept. of Mechanical Engineering

1992-05-01

15

Neutron dosimetry inside the containment building of Spanish nuclear power plants with PADC based dosemeters  

Microsoft Academic Search

The Spanish Nuclear Safety Council (Consejo de Seguridad Nuclear, CSN) recommends performing neutron individual dose assignments at workplaces based on ambient dose equivalent measurements using area monitors and by estimating the amount of time that workers spend in the different monitored environments. In addition, some Spanish nuclear power plants estimate the neutron dose equivalent using albedo thermoluminescence dosemeters (TLD). In

M. J. García-Fusté; C. Domingo; K. Amgarou; T. Bouassoule; J. Castelo

2009-01-01

16

Performance characteristics of neutron personnel dosemeters used in the Oak Ridge intercomparison studies  

Microsoft Academic Search

To provide an opportunity for dosimetrists to test and calibrate their neutron personnel monitoring systems, the staff of the Dosimetry Applications Research Facility at the Oak Ridge National Laboratory (ORNL) has conducted personnel dosimetry intercomparison studies (PDIS) periodically since 1974. During these studies, neutron dosemeters are mailed to ORNL, exposed to low-level (less than 15 mSv) dose equivalents in a

Swaja

1987-01-01

17

Determination of the response function for two personal neutron dosemeter designs based on PADC.  

PubMed

Since 1998 neutron dosimetry based on PADC (poly allyl diglycol carbonate) is done with a so-called original Paul Scherrer Institute (PSI) design at PSI. The original design (i.e. holder) was later changed. Both designs are optimised for use in workplaces around high-energy accelerators, where the neutron energy spectra are dominated by fast neutrons ranging up to some 100 MeV. In addition to the change of the dosemeter design a new evaluation method based on a microscope scanning technique has been introduced and the etching conditions have been optimised. In the present work, the responses obtained with the original and the new dosemeter designs are compared for fields of radionuclide sources and monoenergetic reference fields using the new evaluation method. The response curves in terms of the personal dose equivalent for normally incident neutrons were built as functions of the incident neutron energy. PMID:24179145

Mayer, S; Assenmacher, F; Boschung, M

2014-10-01

18

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

PubMed

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

Olšovcová, V; Klír, D; Krása, J; Kr?s, M; Velyhan, A; Zelenka, Z; Rus, B

2014-10-01

19

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

PubMed

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

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

2001-01-01

20

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

PubMed

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. PMID:12382940

Yasuda, H; Fujitaka, K

2002-01-01

21

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

22

Use of a dual-labelled oligonucleotide as a DNA dosemeter for radiological exposure detection.  

PubMed

A reporter molecule consisting of a synthetic oligonucleotide is being characterised for a novel damage detection scenario for its potential use as a field-deployable, personal deoxyribonucleic acid (DNA) dosemeter for radiation detection. This dosemeter is devoid of any biological properties other than being naked DNA and therefore has no DNA repair capabilities. It supports biodosimetry techniques, which require lengthy analysis of cells from irradiated individuals, and improves upon inorganic dosimetry, thereby providing for a more relevant means of measuring the accumulated dose from a potentially mixed-radiation field. Radiation-induced single strand breaks (SSBs) within the DNA result in a quantifiable fluorescent signal. Proof of concept has been achieved over 250 mGy-10 Gy dose range in radiation fields from ??Co, with similar results seen using a linear accelerator X-ray source. Further refinements to both the molecule and the exposure/detection platform are expected to lead to enhanced levels of detection for mixed-field radiological events. PMID:21335332

Wood, T; Lewis, B J; McDermott, K; Bennett, L G I; Avarmaa, K; Corcoran, E C; Wilkinson, D; Jones, A; Jones, T; Kennedy, E; Prud'homme-Lalonde, L; Boudreau, D; Gravel, J-F; Drolet, C; Kerr, A; Schreiner, L J; Pierre, J R M; Blagoeva, R; Veres, T

2012-01-01

23

Feasibility of a neutron detector-dosemeter based on single-event upsets in dynamic random-access memories.  

PubMed

The feasibility was investigated of a solid-state neutron detector/dosemeter based on single-event upset (SEU) effects in dynamic random-access memories (DRAMs), commonly used in computer memories. Such a device, which uses a neutron converter material to produce a charged particle capable of causing an upset, would be light-weight, low-power, and could be read simply by polling the memory for bit flips. It would have significant advantages over standard solid-state neutron dosemeters which require off-line processing for track etching and analysis. Previous efforts at developing an SEU neutron detector/dosemeter have suffered from poor response, which can be greatly enhanced by selecting a modern high-density DRAM chip for SEU sensitivity and by using a thin 10B film as a converter. Past attempts to use 10B were not successful because the average alpha particle energy was insufficient to penetrate to the sensitive region of the memory. This can be overcome by removing the surface passivation layer before depositing the 10B film or by implanting 10B directly into the chip. Previous experimental data show a 10(3) increase in neutron sensitivity by chips containing borosilicate glass, which could be used in an SEU detector. The results are presented of simulations showing that the absolute efficiency of an SEU neutron dosemeter can be increased by at least a factor of 1000 over earlier designs. PMID:12382721

Phillips, G W; August, R A; Campbell, A B; Nelson, M E; Price, J L; Guardala, N A; Moscovitch, M

2002-01-01

24

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

SciTech Connect

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.

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

1987-01-01

25

Track-etch dosemeter response to neutrons up to 300 MeV  

SciTech Connect

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.

Devine, R.T.; Walker, S.; Staples, P.; Duran, M. [Los Alamos National Lab., NM (United States); Mundis, R.; Miller, J. [Science Applications International Corp., Los Alamos, NM (United States)

1996-04-01

26

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

PubMed

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

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

2012-01-01

27

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

PubMed

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

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

2002-01-01

28

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

29

Study on the response of thermoluminescent dosemeters to synchrotron radiation: experimental method and Monte Carlo calculations.  

PubMed

In the present study, the energy dependence of response of some popular thermoluminescent dosemeters (TLDs) have been investigated such as LiF:Mg,Ti, LiF:Mg,Cu,P and CaSO(4):Dy to synchrotron radiation in the energy range of 10-34 keV. The study utilised experimental, Monte Carlo and analytical methods. The Monte Carlo calculations were based on the EGSnrc and FLUKA codes. The calculated energy response of all the TLDs using the EGSnrc and FLUKA codes shows excellent agreement with each other. The analytically calculated response shows good agreement with the Monte Carlo calculated response in the low-energy region. In the case of CaSO(4):Dy, the Monte Carlo-calculated energy response is smaller by a factor of 3 at all energies in comparison with the experimental response when polytetrafluoroethylene (PTFE) (75 % by wt) is included in the Monte Carlo calculations. When PTFE is ignored in the Monte Carlo calculations, the difference between the calculated and experimental response decreases (both responses are comparable >25 keV). For the LiF-based TLDs, the Monte Carlo-based response shows reasonable agreement with the experimental response. PMID:20308052

Bakshi, A K; Chatterjee, S; Palani Selvam, T; Dhabekar, B S

2010-07-01

30

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

PubMed

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

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

2014-10-01

31

Improvement and calibration of a SSNT personal dosemeter and study of importance of albedo factor for dose calculation.  

PubMed

The Neutriran albedo neutron dosemeter has been improved and calibrated for neutron personal dosimetry. The Monte Carlo code MCNP4b was used to calculate the thermal neutrons backscattered from the body (albedo factor). Backscattering from the wall, ceiling and floor in calibration room was considered also via simulation by MCNP4C. A semi automated counting system applying a high-resolution scanner was used for counting of tracks. An 241Am source was used to produce similar alpha particles from 10B (n,alpha)7Li reaction for the optimisation of scanner parameters to distinguish and separate the tracks in SSNTD, which lead to a better distinction between etched alpha tracks and, consequently, a higher linear region of dose characteristic. PMID:16980708

Torkzadeh, F; Taheri, M

2007-01-01

32

Development of a fibre-optic dosemeter to measure the skin dose and percentage depth dose in the build-up region of therapeutic photon beams.  

PubMed

In this study, a fibre-optic dosemeter (FOD) using an organic scintillator with a diameter of 0.5 mm for photon-beam therapy dosimetry was fabricated. The fabricated dosemeter has many advantages, including water equivalence, high spatial resolution, remote sensing and real-time measurement. The scintillating light generated from an organic-dosemeter probe embedded in a solid-water stack phantom is guided to a photomultiplier tube and an electrometer via 20 m of plastic optical fibre. Using this FOD, the skin dose and the percentage depth dose in the build-up region according to the depths of a solid-water stack phantom are measured with 6- and 15-MV photon-beam energies with field sizes of 10 × 10 and 20 × 20 cm(2), respectively. The results are compared with those measured using conventional dosimetry films. It is expected that the proposed FOD can be effectively used in radiotherapy dosimetry for accurate measurement of the skin dose and the depth dose distribution in the build-up region due to its high spatial resolution. PMID:22764176

Kim, K-A; Yoo, W J; Jang, K W; Moon, J; Han, K-T; Jeon, D; Park, J-Y; Cha, E-J; Lee, B

2013-03-01

33

Short communication The low energy X-ray response of the LiF:Mg:Cu:P thermoluminescent dosemeter: a comparison with LiF:Mg:Ti  

Microsoft Academic Search

LiF:Mg:Cu:P thermoluminescent dosemeters (TLD) can be used for the same X-ray dosimetry applications as LiF:Mg:Ti, with each type having the disadvantage of a response dependent on energy, particularly at low energies. Measurements were made of the response per unit air kerma of LiF:Mg:Cu:P and LiF:Mg:Ti to nine quasi-monoenergetic X-ray beams with mean energies from 12 keV to 208 keV. Each

C R EDWARDS; P J MOUNTFORD; J E PALETHORPE; A J MOLONEY

34

Extremity dosimetry trial: Devonport Royal Dockyard.  

PubMed

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

Kenyon, Rob; Collison, Roger

2008-01-01

35

The effect of beam tube potential variation on gonad dose to patients during chest radiography investigated using high sensitivity LiF:Mg,Cu,P thermoluminescent dosemeters.  

PubMed

Optimization of X-ray beam tube potential (kVp) in radiological examinations can minimize patient dose. This research aims to investigate the effect of tube potential variation on gonad doses to patients during posteroanterior (PA) chest radiography examinations. This study was carried out using a Toshiba general purpose X-ray unit and a Rando phantom. Dose measuring equipment included an ion chamber system, a dose-area product (DAP) meter and a thermoluminescent dosemeter (TLD) reader system with high sensitivity TLD pellets of LiF:Mg,Cu,P for low level gonad dose measurement. PA chest exposures of the phantom to produce a constant exit dose were made using a standard low tube potential (range 60-100 kVp) non-grid technique and a high tube potential (range 95-150 kVp) grid technique. Entrance surface doses (ESDs) and DAPs were also included in the measurements. Effective doses (EDs) were computed from ESD and DAP measurements using NRPB-SR262 and Xdose software. Results show that with the low tube potential technique both ovary dose and testes dose increase with increasing tube potential; statistically significant correlations of r = 0.994 (p = 0.0006) and r = 0.998 (p = 0.001), respectively, were found. For both organs, doses increase at a rate of approximately 2% per kVp. With the high tube potential technique there is insignificant correlation between gonad doses and tube potential. When comparing patient doses from typical exposures made at 70 kVp (low tube potential non-grid technique) with doses from exposures made at 120 kVp (high tube potential grid technique), the high tube potential technique delivers significantly higher values for ESD, and ovary, testes and effective doses by factors of 1.7, 5.2, 5.5 and 2.7, respectively. PMID:11387155

Fung, K K; Gilboy, W B

2001-04-01

36

Lithium-gadolinium-borate as a neutron dosemeter.  

PubMed

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

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

2007-01-01

37

Preliminary results on bubble detector as personal neutron dosemeter.  

PubMed

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

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

2011-03-01

38

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

USGS Publications Warehouse

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

Houser, Brenda B.

2005-01-01

39

Pre-read and post-read annealing techniques for the Harshaw/Filtrol Inc. CaSO?:Dy beta TDL chip  

E-print Network

of low energy traps) and over reporting of the measured dose due to energy previously stored within the chip. Following well defined annealing protocols will minimize these causes of error in TL output. The objective of this research was to study...- ray or neutron TLD chips. The TLD chip should demonstrate high sensitivity and accuracy, a linear relationship between absorbed dose and TL output over a large range, dose rate independence, a low LLD, a flat energy response curve, minimal angular...

McCarthy, Daniel Patrick

2012-06-07

40

A comparison of personal dose equivalent measurements made by personal dosemeters  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

41

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

SciTech Connect

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.

Streil, T.; Oeser, V. [SARAD GmbH, Wiesbadener Str. 10-20, D-01159 Dresden (Germany); Rambousky, R.; Buchholz, F. W. [SARAD GmbH, Wiesbadener Str. 10-20, D-01159 Dresden (Germany); Armed Forces Scientific Institute for Protection Technologies-NBC Protection PO.Box 1142, 29633 Munster (Germany)

2008-08-07

42

Response of thermoluminescence dosemeters statically exposed to X-ray radiation  

Microsoft Academic Search

Using a two-dimensional thermo luminescent (TL) system consisting of MCP-N (LiF:Mg,Cu,P) TL detectors and self-developed TLD reader with a CCD camera (TL-CCD reader) a method of distinguishing between static and dynamic radiation exposure to X-rays was developed. MCP-N TL detectors installed in the RADOS dosimetry badge were covered with non-uniform Pb and Cu filters. Quantitative identification of the static exposure

R. Kope?; M. Budzanowski; P. Olko; W. Gieszczyk; K. Szewczak

43

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

SciTech Connect

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.

Schwartz, P.E.

1989-01-01

44

Thermoluminescence solid-state nanodosimetry--the peak 5A/5 dosemeter  

PubMed Central

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

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

2011-01-01

45

Assessing the potential for using biogenic calcites as dosemeters for luminescence dating  

Microsoft Academic Search

Calcium carbonate emits an intense thermoluminescence (TL) signal and previous work has explored the potential of using this signal to date both inorganic carbonates such as limestones and stalagmites and biogenic calcite produced by marine organisms. Luminescence analysis of biogenic calcites directly dates the secretion of the mineral by the organism and is therefore not reliant upon exposure of the

G. A. T. Duller; K. E. H. Penkman; A. G. Wintle

2009-01-01

46

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

PubMed

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

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

2006-01-01

47

The effect of beam tube potential variation on gonad dose to patients during chest radiography investigated using high sensitivity LiF:Mg,Cu,P thermoluminescent dosemeters  

Microsoft Academic Search

Optimization of X-ray beam tube potential (kVp) in radiological examinations can minimize patient dose. This research aims to investigate the effect of tube potential variation on gonad doses to patients during posteroanterior (PA) chest radiography examinations. This study was carried out using a Toshiba general purpose X-ray unit and a Rando phantom. Dose measuring equipment included an ion chamber system,

K K L FUNG; W B GILBOY

48

Monte Carlo simulations to study fast neutron real-time personal diamond and silicon dosemeters: Sensitivity calculations and background transparency analysis  

NASA Astrophysics Data System (ADS)

Different Monte Carlo codes have been used to study diamond detectors in real-time personal fast neutron dosimetry. Some specific ones include a digital counting processing with an acceptance cut-off set on the detector pulse-height to achieve low dose measurements necessary in personal safety controls. This method is also used to avoid several background contaminations, as, for instance, that of gamma-ray signals in mixed neutron-gamma fields, or that induced by neutrons spallation reactions on the carbon atoms. It is also proposed to extract responses from different neutron energy spectra around power plants or in fusion experiments. Diamond detection efficiencies are calculated for parallel and dispersed mono-energetic neutron beam irradiation between 100 keV and 16 MeV. The interest of many detection channels against response accuracy and background removal is discussed for gamma-ray filters, neutron converters, pulse-height acceptances and sensor properties. In the range from 0.75 to 7 MeV, diamond and silicon based monitors of similar interaction volumes but with different acceptance cut-offs show comparable sensitivities near 2.5 microsievert per pulse with less than 25% maximum response dispersions.

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

2007-09-01

49

Measurement of neutron spectra for determining dose equivalent rates at the Texas A&M University Nuclear Science Center  

E-print Network

above is changed in the code so that the total neutron flux is the same as that determined by Schoenbucher (Sc77). HELIUM-3 PROPORTIONAL COUNTER The He detector used in this study was a custom detector built by Harshaw Chemical Co... above is changed in the code so that the total neutron flux is the same as that determined by Schoenbucher (Sc77). HELIUM-3 PROPORTIONAL COUNTER The He detector used in this study was a custom detector built by Harshaw Chemical Co...

Sanza, Bruce Jerome

2012-06-07

50

THE SEASONAL DISTRIBUTION AND ABUNDANCE OF HUMMINGBIRDS IN OAK WOODLAND AND RIPARIAN COMMUNITIES IN SOUTHEASTERN ARIZONA  

Microsoft Academic Search

We examined the distribution and abundance of hummingbirds at two study sites in southeastern Arizona, where we banded over 8000 individuals and 11 species in a 6-year period. We trapped approximately once a week from April to October at each site, from 1988-1992 at Sonoita, in oak woodlands, and 1991-1993 at Harshaw Creek, in a riparian area. Anna's ( Calypte

Susan M. Wethington; Stephen M. Russell

2003-01-01

51

Thermoluminescent dosimeters (TLD) quality assurance network in the Czech Republic  

Microsoft Academic Search

Introduction: The Czech thermoluminescent dosimeters (TLD) quality assurance network was established in 1997. Its aim is to pursue a regular independent quality audit in Czech radiotherapy centres and to support state supervision.Materials and methods: The audit is realised via mailed TL dosimetry. The TLD system consists of encapsulated LiF:Mg,Ti powder (type MT-N) read with Harshaw manual reader model 4000. Basic

Daniela Kroutil??ková; Josef Novotný; Libor Judas

2003-01-01

52

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

Microsoft Academic Search

Catalyst deactivation data, obtained from the HDS of a Greek oil residue on a spinning basket laboratory scale reactor, are reported in this paper. Two commercial grade hydrodesulfurization (HDS) catalysts, viz., Harshaw HT-400 E and ICI-41-6, were used in the investigation. Initial activities and modes of activity loss vs. run time are compared (HT-400 E possessed an initial activity 25%

Jamal M. Ammus; George P. Androutsopoulos; Athena H. Tsetsekou

1987-01-01

53

Microprocessor controlled portable TLD system  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

54

Hand exposure to ionising radiation of nuclear medicine workers.  

PubMed

The specific nature of work in nuclear medicine departments involves the use of isotopes and handling procedures, which contribute to the considerable value of an equivalent dose received, in particular, by the fingertips. Standard nuclear medicine department uses ring dosemeters placed usually at the base of the middle finger. The main aim of the study was to find out whether a relationship exists between the doses recorded by thermoluminescent detectors placed at various locations on the radiopharmacists' hands and the doses recorded by the ring detectors, and to determine the character of that relationship. The correction factor represents a correction value to be used to calculate the doses which might be received by locations on the hand from the dose recorded by the ring dosemeter. The dose recorded by the ring dosemeter is on the average five times lower than that received by the fingertips of thumb, index and middle fingers. PMID:18310609

Wrzesie?, M; Olszewski, J; Jankowski, J

2008-01-01

55

Variations observed in environmental radiation at ground level.  

PubMed

To investigate and monitor environmental radiation at ground level, Physikalisch-Technische Bundesanstalt (PTB) has installed several dosemeters and particle detectors at the new Ambient Radiation Dosimetry Site. The separation of the total ambient dose equivalent rate H*10(env) of environmental radiation into the different contributions is achieved by comparing the data of different detectors: the muon detector MUDOS, a modified neutron dosemeter, proportional counters and ionisation chambers. The response of the latter two dosemeter systems to cosmic radiation was determined at the Cosmic Radiation Dosimetry Site on a lake near PTB. Besides the increase of the ambient dose equivalent rate during rainfall, variations owing to air pressure, solar activity and temperature changes in the upper atmosphere are observed. Without rain and solar effects, smooth variations of the cosmic component at ground level of +/-6.9 nSv h(-1) should be treated as naturally occurring variations during an entire year. PMID:15985498

Wissmann, F

2006-01-01

56

RisS-M-2389 ACCELERATOR DEPARTMENT  

E-print Network

Ris«S-M-2389 ACCELERATOR DEPARTMENT Annual Progress Report 1 January - 31 December 1982 Abstract as of the operation of various irradiation facilities. INIS-descriptors: ACCELERATOR FACILITIES; BACTERIA; DOSEMETERS FACILITIES 30 4.1 HRC electron linear accelerator 30 4.2 Febetron, field-emission accelerator 31 4.3 ICT, low

57

RISC-M-2t9i ACCELERATOR DEPARTMENT  

E-print Network

RISC-M-2t9i » ACCELERATOR DEPARTMENT Annual Progress Report 1 January - 31 December 1984 Abstract ACCELERATOR FACILITIES; BACTERIA; DOSEMETERS; DOSIMETRY; IRRADIATION DEVICES; RADIATION CHEMISTRY; REACTION. OPERATION AND MAINTENANCE OF IRRADIATION FACILITIES 25 4.1 HRC electron linear accelerator 25 4.2 Febetron

58

Risa-M-2423 ACCELERATOR DEPARTMENT  

E-print Network

Risa-M-2423 ACCELERATOR DEPARTMENT Annual Progress Report 1 January - 31 December 1983 Abstract as of the operation of various irradiation facilities. INIS-descriptors ACCELERATOR FACILITIES; BACTERIA; DOSEMETERS OPERATION AND MAINTENANCE OF IRRADIATION FACILITIES 26 4.1 HRC electron linear accelerator 26 4.2 Febetron

59

RIS-M-2559 ACCELERATOR DEPARTMENT  

E-print Network

RISĂ?-M-2559 ACCELERATOR DEPARTMENT Annual Progress Report 1 January - 31 December 1985 Abstract irradiation facilities. INIS-descriptors. ACCELERATOR FACILITIES; DOSEMETERS; DOSIMETRY; IRRADIATION DEVICES.5 References 21 3. OPERATION AND MAINTENANCE OF THE IRRADIATION FACILITY 24 3.1 HRC electron linear accelerator

60

Rise-M-2173 ACCELERATOR DEPARTMENT  

E-print Network

Rise-M-2173 ACCELERATOR DEPARTMENT Annual Progress Report 1 January - 31 December 1978 Abstract- radiation facilities. INIS-descriptors: ACCELERATOR FACILITIES, BACTERIA, DOSEMETERS, DOSIMETRY, IRRADIATION.1 HRC electron linear accelerator 2 1.2 Febetron, field emission accelerator 3 1.3 ICT, low energy

61

RIS-M-2231 ACCELERATOR DEPARTMENT  

E-print Network

RISĂ?-M-2231 ACCELERATOR DEPARTMENT Annual Progress Report 1 January - 31 December 1979 Abstract irradiation facilities. INIS-descriptorS: ACCELERATOR FACILITIES, BACTERIA, DOSEMETERS, DOSIMETRY, IRRADIATION AND MAINTENANCE OF IRRADIATION FACILITIES ... 8 1.1. HRC electron linear accelerator 8 1.2. Febetron, field

62

Solar dosimetry of the face: the relationship of natural ultraviolet radiation exposure to basal cell carcinoma localisation  

Microsoft Academic Search

Measurements have been made of the distribution of natural ultraviolet radiation (UVR) at 41 sites on the face of a large fibreglass model of a head. The dosemeter used was the polymer film polysulphone. The results have been correlated with published values of the distribution of basal cell carcinomas on the face. Although the comparison has highlighted the problems of

B L Diffey; T J Tate; A Davis

1979-01-01

63

RIS-M-2302 LIST OF SELECTED PUBLICATIONS 1980  

E-print Network

, The Cold Neutron Source in DR 3. Riso-M-2246 (1980) 30 pp. Krenk, S., First-Passage Times and Extremes Neutron Dosemeter. Risø-M- 2247 (1980) 14 pp. Hvidtfeldt Larsen, A. M., The Three-Dimensional PWR

64

Correlation of patient skin doses in cardiac interventional radiology with dose-area product  

Microsoft Academic Search

The use of X-rays in cardiac interventional radiology has the potential to induce deterministic radiation effects on the patient's skin. Guidelines published by official organizations encourage the recording of information to evaluate this risk, and the use of reference values in terms of the dose-area product (DAP). Skin dose measurements were made with thermo- luminescent dosemeters placed at eight different

S VAN DE PUTTE; F VERHAEGEN; Y TAEYMANS; H THIERENS

65

Differences in using the international commission on radiological protection’s publications 60 and 103 for determining effective dose in paediatric CT examinations  

Microsoft Academic Search

The use of computed tomography (CT) worldwide is continuing to increase for both adults and children, posing population health risks due to radiation exposure. These risks are highest for children, reducing with age at exposure. Effective dose is a useful parameter for expressing relative risk and comparing dose. In this study, high sensitivity thermoluminescence dosemeters (TLD) were used to measure

Z. Brady; T. M. Cain; P. N. Johnston

66

*** 1 CJ O w Ris-M-2689  

E-print Network

radon dosemeter 11 3.4. Continuous radon monitor 13 3.5. Collection of meteorological data 15 3 and minimum in the summer. A deviating seasonal varia- tion wab found in three of the houses. Hourly data between the indoor radon concentration and meteorological factors. However, for most of the houses

67

Ris-R-1216(EN) Development of a Portable Triple  

E-print Network

and Skin Dosimetry Jakob Helt-Hansen Risø National Laboratory, Roskilde, Denmark November 2000 #12;Abstract. There is thus a need for a portable and rugged active beta dosemeter-spectrometer to carry out immediate all subsequent data analysis. The LabViewTM software distributed by National Instruments was used

68

Analysis of the Neutron Component and Determination of the LET Spectrum at High Altitudes  

Microsoft Academic Search

6 LiI(Eu) scintillation counter and thermoluminescent dosemeters (TLDs), respectively, were used to determine the neutron energy spectrum as well as the absorbed dose and the average linear energy transfer (LET) in a complex mixed radiation field on top of Mt. Sonnblick (3105 m). The neutron component makes up 35 to 60 % of the biologically relevant dose at high altitudes,

N. Vana; T. Berger; M. Hajek; M. Minarik; M. Noll; W. Schöner

69

Comparison of Different Detector Performance for the Assessment of Neutron Personal Equivalent Dose in Nuclear Power Plants  

Microsoft Academic Search

In Spain the Nuclear Safety Council (CSN) recommends the use of neutron survey monitors to measure the ambient dose equivalent rate at the workplace and then the individual do se is calculated by taking into account the length of permanence at the monitored site. In spite of this recommendation, some nuclear power plants prefer to use TLD dosemeters for estimating

M. Ginjaume; X. Ortega; A. Duch; F. Fernández

70

RIS-M-2483 A PILOT INVESTIGATION OP NATORAL RADIATION IN DANISH HOUSES  

E-print Network

RISø-M-2483 A PILOT INVESTIGATION OP NATORAL RADIATION IN DANISH HOUSES A. Sørensen, L. Bøtter-Jensen, B. Majborn, and S.P. Nielsen Health Physics Department Abstract. As a prelude to a nationwide survey radiation in Denmark. A passive cup dosemeter was designed containing CR39 track detectors and TLD

71

Fire testing of bare uranium hexafluoride cylinders  

SciTech Connect

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.

Pryor, W.A. [PAI Corp., Oak Ridge, TN (United States)

1991-12-31

72

Fire testing of bare uranium hexafluoride cylinders  

SciTech Connect

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.

Pryor, W.A. [PAI Corp., Oak Rige, TN (United States)

1991-12-31

73

Study of the improvement of TLD cards for personal neutron dosimetry  

NASA Astrophysics Data System (ADS)

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

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

74

Tenth ORNL Personnel Dosimetry Intercomparison Study  

SciTech Connect

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.

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

1985-03-01

75

EURADOS IC2012N: EURADOS 2012 intercomparison for whole-body neutron dosimetry.  

PubMed

The European Radiation Dosimetry Group (EURADOS) IC2012n intercomparison for neutron dosemeters intended to measure personal dose equivalent, Hp(10), was performed in 2012. A total of 31 participants (27 individual monitoring services from Europe, 2 from Japan, 1 from Israel and 1 from USA) registered with 34 dosimetry systems. Participation was restricted to passive or active neutron dosemeters routinely used in individual monitoring of radiation workers. The dosimetry systems were based on thermoluminescence, polyallyldiglycol carbonate, optically stimulated luminescence, fission track detection and silicon diodes (electronic devices). The irradiation tests were chosen to provide the participants with useful information on their dosimetry systems, i.e. linearity, reproducibility, responses for different energies and angles and to simulated workplace fields. The paper will report and discuss the first analysis of the results of the EURADOS IC2012n intercomparison. PMID:24578527

Fantuzzi, E; Chevallier, M-A; Cruz-Suarez, R; Luszik-Bhadra, M; Mayer, S; Thomas, D J; Tanner, R; Vanhavere, F

2014-10-01

76

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

PubMed

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

Kim, Hee Geun; Kong, Tae Young

2013-05-01

77

Characterisation of the TAPIRO BNCT thermal facility.  

PubMed

Dosimetry and spectrometry measurements have been carried out in the thermal column of the research fast reactor RSV-TAPIRO (ENEA-Casaccia, Rome) in order to investigate its suitability for irradiation of cells or mice, with a view to research in the interests of boron neutron capture therapy (BNCT). The thermal column consists of a graphite moderator (40 cm thick) containing a lead shield (13 cm thick) in order to shield reactor background. The irradiation volume, inside this structure, has cubic shape (18 x 18 x 18 cm3). Besides measurements of fluence and dose rates in air or in phantom performed with thermoluminescence dosemeters (TLDs) and using the activation technique, dose and fluence profiles have been generated using a method based on gel dosemeters analysed with optical imaging. To check the consistency of the results, spectrometry measurements in the same irradiation volume have been performed by means of bubble detectors. PMID:15353725

Rosi, G; Gambarini, G; Colli, V; Gay, S; Scolari, L; Fiorani, O; Perrone, A; Nava, E; Fasolo, F; Visca, L; Zanini, A

2004-01-01

78

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

PubMed

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

Passmore, C; Kirr, M

2011-03-01

79

Retrospective dosimetry with alumina substrate from electronic components.  

PubMed

Alumina substrate can be found in electronic components used in portable electronic devices. The material is radiation sensitive and can be applied in dosimetry using thermally or optically stimulated luminescence. Electronic portable devices such as mobile phones, USB flash discs, mp3 players, etc., which are worn close to the body, can represent  personal dosemeters for members of the general public in situations of large-scale radiation accidents or malevolent acts with radioactive materials. This study investigated dosimetric properties of alumina substrates and aspects of using mobile phones as personal dosemeters. The alumina substrates exhibited favourable dosimetry characteristics. However, anomalous fading had to be properly corrected in order to achieve sufficient precision in dose estimate. Trial dose reconstruction performed by means of two mobile phones proved that mobile phones can be used for reconstruction of personal doses. PMID:21964904

Ekendahl, Daniela; Judas, Libor

2012-06-01

80

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

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)

Bair, W.J.

1985-02-01

81

Neutron spectrometry with CR39 track detectors and silicon diodes using unfolding techniques  

Microsoft Academic Search

A combination personal neutron dosemeter with spectrometric properties is proposed. The system consists of a passive CR-39 track detector and an active silicon diode. The response functions (pulse height spectra for diodes and track diameter distributions for track detectors) were first determined with monoenergetic neutrons in the energy range from 1.2 to 19 MeV. The unfolding of different simulated spectral

M. Luszik-Bhadra; E. Dietz; F. D'Errico; S. Guldbakke; M. Matzke

1997-01-01

82

Personal monitoring of 218Po and 214Po radionuclide deposition onto individuals under normal environmental exposure conditions.  

PubMed

Personal dosemeters have been utilized to monitor the deposition of the radon decay products 218Po and 214Po onto individuals under normal environmental exposure conditions. Each detector consists of TASTRAK alpha-sensitive plastic incorporated into an ordinary working wristwatch. Subsequent analysis provides energy discrimination of the detected alpha-particle decays, and allows events from the individual radon decay products 218Po and 214Po, attached to the detector surface, to be uniquely identified. Assuming similar deposition onto skin and detector surfaces, the activity per unit area of deposited radionuclides can be determined for exposed skin. Forty-one personal dosemeters were issued to volunteers selected through the hospital medical physics departments at Reading, Northampton, Exeter and Plymouth. Each volunteer was also issued with a personal radon dosemeter to determine their individual radon exposure. The volunteers wore the two dosemeters simultaneously and continuously for a period of around one month. Correlations were observed between the radon exposure of the individual and the activity per unit area of 218Po and 214Po on the detector surface. From these correlations it can be estimated that at the UK average radon exposure of 20 Bq m(-3), the number of decays/cm2/year on continuously exposed skin surface is between 3500 and 28,000 for 218Po, and between 7000 and 21,000 for 214Po. These results can be combined with theoretical modelling of the dose distribution in the skin to yield the alpha-particle radiation dose to any identified target cells. PMID:10495117

Eatough, J P; Worley, A; Moss, G R

1999-09-01

83

Monitoring the eye lens: which dose quantity is adequate?  

NASA Astrophysics Data System (ADS)

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.

Behrens, R.; Dietze, G.

2010-07-01

84

Performance assessment of patient dosimetry services and X-ray quality assurance instruments used in diagnostic radiology  

Microsoft Academic Search

Experiences of the Regional Radiation Physics and Protection Service (RRPPS) in performance assessment of diagnostic X-ray QA instrumentation and on-patient dosemeters are recounted. Issues relating to the provision of realistic and reproducible reference conditions for calibrated X-irradiations are considered and summary statistics from test measurements of dose and kVp meters are provided. For both dose and kVp meters it is

S. Green; J. E. Palethorpe; D. Peach; D. A. Bradley

1999-01-01

85

Scattered radiation in a neonatal surgical unit.  

PubMed

We studied the doses of "scattered" received by neonates in a Neonatal Surgical Unit by placing thermoluminescent dosemeters in various positions expect the direct beam. Doses of "scattered" radiation received by neonates as a results of exposure of their neighbours to X-ray examinations were found to be negligible. Sick neonates need not be moved from their neighbours undergoing exposure to X-rays. PMID:8555132

Iyer, K R; Spitz, L; Kiely, E; Drake, D P; Dykes, E; Evans, K; Wallace, M; Brereton, R J

1995-10-01

86

Dose mapping of a 60Co irradiation facility using PENELOPE and MCNPX and its validation by chemical dosimetry  

Microsoft Academic Search

The Monte Carlo simulation programs PENELOPE and MCNPX have been used for simulating the dose rate distribution in a 60Co gamma irradiator.The simulated isodose curves obtained for each simulation code were validated comparing them to the dose measurements performed with a Fricke solution, which is a standard dosemeter widely used in radiation processing for calibration purposes.The agreement between the simulated

A. Belchior; M. L. Botelho; L. Peralta; P. Vaz

2008-01-01

87

Radiation streaming experiment through a labyrinth of the 12 GeV proton accelerator facility at KEK(2)--TLD REM-counter method.  

PubMed

The doses of radiation streaming through a labyrinth were measured using thermoluminescence dosemeters (TLDs) and neutron moderators for TLDs at the neutrino beam line of the 12 GeV proton accelerator facility of High Energy Accelerator Research Organization (KEK). The calculated doses using the Monte Carlo code, MCNPX basically agreed with the experimental results. However, unexpectedly, the calculated neutron doses were smaller than the measured ones along the upstream side of the labyrinth. PMID:16604638

Nakamura, H; Miura, T; Numajiri, M; Nakao, N; Nakashima, H; Matsuda, N; Watanabe, S

2005-01-01

88

Characterisation of OSL and OSLN droplets for dosimetry.  

PubMed

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

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

2014-10-01

89

Sensitivity variation of doped Fricke gel irradiated with monochromatic synchrotron X rays between 33.5 and 80 keV.  

PubMed

An experimental binary radiotherapy proposes the concomitant use of a high-Z compound and synchrotron X rays for enhancing radiation dose selectively in tumours by a photoelectric effect. This study aimed at measuring the resulting dose enhancement in irradiated material. A doped Fricke gel dosemeter model was manufactured with 10 mg ml(-1) of iodine (Telebrix) or barium (Micropaque). Samples were irradiated with a monochromatic synchrotron beam at 33.5, 50, 65 and 80 keV. The ensuing enhancement of the sensitivity of the dosemeter was derived from the nuclear magnetic resonance relaxation rates measured at different X-ray doses. Our results demonstrate (1) the preservation of a linear relationship between relaxation rates and X-ray doses for dosemeters doped with high-Z atoms and (2) a clear energy-dependent sensitivity enhancement for barium-doped Fricke gels. This enhancement was neither reproducible with iodinated compounds nor clearly related to the expected dose enhancement factor. However 1% barium sulphate in the gel could significantly improve the gel's response when it was irradiated by low-energy X rays. PMID:15956218

Corde, Stéphanie; Adam, Jean-François; Biston, Marie-Claude; Joubert, Aurélie; Charvet, Anne-Marie; Estčve, François; Le Bas, Jean-François; Elleaume, Hélčne; Balosso, Jacques

2005-01-01

90

Measurement of the fluence response of the GSI neutron ball in high-energy neutron fields produced by 500 AMeV and 800 AMeV deuterons.  

PubMed

Experiments were performed in Cave C of GSI (Gesellschaft für Schwerionenforschung) using the LAND (Large Area Neutron Detector) in combination with the deflection magnet ALADIN (A LArge DIpol magNet) in front of the LAND where charged particles and neutrons can be separated. This arrangement is used to create high-energetic neutron fields by irradiation of a thick lead target (5 cm) with deuteron beams with the energies of 500 or 800 MeV per nucleon. In break-up reactions the neutron is separated from the proton which is deflected in the magnetic field of the ALADIN. The produced neutron radiation, which has a pronounced peak at the nucleon energy, is used to measure the fluence response of the GSI neutron ball. A thermoluminescence (TL) based spherical neutron dosemeter was developed for the area monitoring for the quantity H(10) at high-energy accelerators. In the same experiment, the spectral neutron fluence Phi(E) is measured with the LAND in the energy range from 100 MeV to 1 GeV. The measured fluence responses are compared with results of FLUKA calculations and the corresponding fluence-to-dose conversion coefficients. The measured dosemeter responses are too high in comparison to the calculated ones (up to approximately 50%), the dosemeter reading gives dose values which are too high by a factor of 1.1-2.2 related to the corresponding fluence-to-dose conversion factors. PMID:17519242

Fehrenbacher, G; Gutermuth, F; Kozlova, E; Radon, T; Aumann, T; Beceiro, S; Le Bleis, T; Boretzky, K; Emling, H; Johansson, H; Kiselev, O; Simon, H; Typel, S

2007-01-01

91

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

PubMed

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

Cauwels, Vanessa; Vanhavere, Filip; Reginatto, Marcel

2014-10-01

92

Single crystal diamond detector for radiotherapy  

NASA Astrophysics Data System (ADS)

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.

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

2010-07-01

93

Dose received by occupationally exposed workers at a nuclear medicine department  

NASA Astrophysics Data System (ADS)

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.

Ávila, O.; Sánchez-Uribe, N. A.; Rodríguez-Laguna, A.; Medina, L. A.; Estrada, E.; Buenfil, A. E.; Brandan, M. E.

2012-10-01

94

Occupational radiation dose to eyes from endoscopic retrograde cholangiopancreatography procedures in light of the revised eye lens dose limit from the International Commission on Radiological Protection  

PubMed Central

Objective: Endoscopic retrograde cholangiopancreatography (ERCP) is a common procedure that combines the use of X-ray fluoroscopy and endoscopy for examination of the bile duct. Published data on ERCP doses are limited, including staff eye dose from ERCP. Occupational eye doses are of particular interest now as the International Commission on Radiological Protection (ICRP) has recommended a reduction in the dose limit to the lens of the eye. The aim of this study was to measure occupational eye doses obtained from ERCP procedures. Methods: A new eye lens dosemeter (EYE-D™, Radcard, Krakow, Poland) was used to measure the ERCP eye dose, Hp(3), at two endoscopy departments in Ireland. A review of radiation protection practice at the two facilities was also carried out. Results: The mean equivalent dose to the lens of the eye of a gastroenterologist is 0.01?mSv per ERCP procedure with an undercouch X-ray tube and 0.09?mSv per ERCP procedure with an overcouch X-ray tube. Staff eye dose normalised to patient kerma area product is also presented. Conclusion: Staff eye doses in ERCP have the potential to exceed the revised ICRP limit of 20?mSv per annum when an overcouch X-ray tube is used. The EYE-D dosemeter was found to be a convenient method for measuring lens dose. Eye doses in areas outside of radiology departments should be kept under review, particularly in light of the new ICRP eye dose limit. Advances in knowledge: Occupational eye lens doses from ERCP procedures have been established using a new commercially available dedicated Hp(3) dosemeter. PMID:23385992

Gallagher, A; Malone, L; O'Reilly, G

2013-01-01

95

Inhalation and external doses in coastal villages of high background radiation area in Kollam, India.  

PubMed

The observational evidence for radiation-induced health effects in humans comes largely from the exposures to high doses received over short periods of time. The rate of induction of any health risk at low doses and dose rates is estimated by extrapolation from observations at high doses. Effects of low dose/low dose rate could be done by the study of populations that have been exposed to slightly above-average natural radiation doses. Southwest coastal line of the Kerala state in India is one such region known to have elevated levels of background radioactivity mainly due to the mineral-rich sand available with high abundance of thorium. In the present work, a study was conducted to investigate the inhalation and external radiation doses to human beings in the high background radiation area along the southwest coast of Kerala. Five hundred dwellings were selected for the study. All the selected houses were at least 10 y old with similar construction. Long-term integrated indoor measurements of the external gamma dose using thermoluminescent dosemeters (TLDs) and the inhalation dose with the SSNTD-based twin-cup dosemeters were carried out in the dwellings simultaneously. Ambient gamma dose measurements were also made with a GM tube-based survey meter while deploying and retrieving the dosemeters. The data show a high degree of heterogeneity. The inhalation dose was found to vary from 0.1 to 3.53 mSv y(-1) and the external dose rates had a range of 383-11419 µGy y(-1). The external doses measured by the survey meter and TLDs showed an excellent correlation. PMID:22961502

Ben Byju, S; Koya, P K M; Sahoo, B K; Jojo, P J; Chougaonkar, M P; Mayya, Y S

2012-11-01

96

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

NASA Astrophysics Data System (ADS)

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).

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

97

Photon doses in NPL standard neutron fields.  

PubMed

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

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

2014-10-01

98

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

PubMed

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

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

1976-01-01

99

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

PubMed

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

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

2014-10-01

100

Neutron dosimetry with 6LiF-rich TL sheet.  

PubMed

A (6)LiF-rich thermoluminescent sheet-type dosemeter ((6)LiF-rich NTL sheet) was developed for neutron 2D dosimetry. The dosemeter utilises the (6)Li(n, alpha)(3)H reaction to detect thermal neutrons. Responses of the (6)LiF-rich NTL sheet to neutrons were measured at the neutron beam irradiation facility for BNCT in JRR-4 Research Reactor at the Japan Atomic Energy Research Institute. Placement of a multi-leaf collimator at the output port of the neutron (beam) irradiation facility, produced either stripe- or round-shaped neutron distributions; the spatial distribution was measured using the developed NTL sheets. Direct measurements of neutron attenuation in water were also carried out using the developed NTL sheet, submersed in a water phantom. In each experiment, NTL sheets having natural abundance (7.9%) of LiF, and (6)LiF-enriched NTL (18.94%) sheet were irradiated under the same conditions. The ratio of thermoluminescence intensities of the (6)LiF-rich NTL sheet to that of the normal NTL sheet was compared to a theoretically calculated value. The experimental measurements are shown to be in good agreement with the calculations. PMID:16709707

Konnai, Akiko; Odano, Naoteru; Nariyama, Nobuteru; Ohnishi, Seiki; Nakajima, Nobuya; Yamamoto, Kazuyoshi; Kishi, Toshiaki; Ozasa, Naoto; Ishikawa, Yuhzoh

2006-01-01

101

History of personal dosimetry performance testing in the United States.  

PubMed

The basis for personal dosimetry performance testing in the United States is ANSI/HPS N13.11 (2001). Now in its third edition, this standard has been in place since 1983. Testing under this standard is administered by the National Voluntary Accreditation Program (NVLAP), and accreditation of dosimetry processors under this program is required by US Nuclear Regulatory Commission (NRC) regulations. The US Department of Energy (DOE) also maintains a testing program for its laboratories and contractors, administered by the Department of Energy Laboratory Accreditation Program (DOELAP). A focus in recent years has been the modification of ANSI/HPS N13.11 to allow acceptance by both testing programs in order to bring harmonisation to US personal dosemeter processing testing. Since there is no type testing program in the US for personal dosemeters, the testing philosophy of ANSI N13.11 has always combined elements of type testing and routine performance testing. This philosophy is explored in detail in this presentation, along with trends in the development of the document to its present state. In addition, a look will be taken at what the future holds for the next revision of the document, scheduled to begin in 2005. PMID:17287202

Soares, C G

2007-01-01

102

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

PubMed

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

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

2014-06-01

103

Gel dosimetry in the BNCT facility for extra-corporeal treatment of liver cancer at the HFR Petten.  

PubMed

A thorough evaluation of the dose inside a specially designed and built facility for extra-corporeal treatment of liver cancer by boron neutron capture therapy (BNCT) at the High Flux Reactor (HFR) Petten (The Netherlands) is the necessary step before animal studies can start. The absorbed doses are measured by means of gel dosemeters, which help to validate the Monte Carlo simulations of the spheroidal liver holder that will contain the human liver for irradiation with an epithermal neutron beam. These dosemeters allow imaging of the dose due to gammas and to the charged particles produced by the (10)B reaction. The thermal neutron flux is extrapolated from the boron dose images and compared to that obtained by the calculations. As an additional reference, Au, Cu and Mn foil measurements are performed. All results appear consistent with the calculations and confirm that the BNCT liver facility is able to provide an almost homogeneous thermal neutron distribution in the liver, which is a requirement for a successful treatment of liver metastases. PMID:17496302

Gambarini, G; Daquino, G G; Moss, R L; Carrara, M; Nievaart, V A; Vanossi, E

2007-01-01

104

Intercomparison of radiation protection instrumentation in a pulsed neutron field  

NASA Astrophysics Data System (ADS)

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.

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

105

Verification of an effective dose equivalent model for neutrons  

SciTech Connect

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.

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

1991-10-01

106

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

PubMed

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

Sannappa, J; Ningappa, C

2014-03-01

107

Doses to operators during interventional radiology procedures: focus on eye lens and extremity dosimetry.  

PubMed

The present study is focused on the personnel doses during several types of interventional radiology procedures. Apart from the use of the official whole body dosemeters (thermoluminescence dosemeter type), measurements were performed to the extremities and the eyes using thermoluminescent loose pellets. The mean doses per kerma area product were calculated for the monitored anatomic regions and for the most frequent types of procedures. Higher dose values were measured during therapeutic procedures, especially embolisations. The maximum recorded doses during a single procedure were 1.8 mSv to the finger (nephrostomy), 2.1 mSv to the wrist (liver chemoembolisation), 0.6 mSv to the leg (brain embolisation) and 2.4 mSv to the eye (brain embolisation). The annual doses estimated for the operator with the highest workload according to the measurements and the system's log book were 90.4 mSv to the finger, 107.9 mSv to the wrist, 21.6 mSv to the leg and 49.3 mSv to the eye. Finally, the effect of the beam angulation (i.e. projection) and shielding equipment on the personnel doses was evaluated. The measurements were performed within the framework of the ORAMED (Optimization of RAdiation Protection for MEDical staff) project. PMID:21044993

Koukorava, C; Carinou, E; Simantirakis, G; Vrachliotis, T G; Archontakis, E; Tierris, C; Dimitriou, P

2011-03-01

108

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

PubMed

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

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

2014-01-01

109

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

USGS Publications Warehouse

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

Folger, Helen W.; Gray, Floyd

2013-01-01

110

Brain damage among mentally disordered sex offenders.  

PubMed

The incidence and nature of structural brain dysfunction was investigated in a pilot study sample of individuals currently assigned the Nebraska Penal Code designation of mentally disordered sexual offender. It was hypothesized that the sexual offenders would show a significantly higher incidence of dysfunction than a psychosocially normal group as evidenced by computed tomography scan measures, regional cerebral blood flow, and neuropsychological instruments. The hypothesis was tested by two different methods. One method used a 160 by 160 printout of density numbers generated by computer from computed tomography scans administered to the sexual offenders. The second method used mean blood flow data generated from a Harshaw TASC-5 Regional Cerebral Blood Flow analysis system. Additionally, the Luria-Nebraska Neuropsychological Test Battery was administered as a measure of the behavioral correlates of brain dysfunction. Preliminary analyses indicate that 50% of the sexual offenders tested showed brain dysfunction as demonstrated by decreased density measures, decreased blood flow, and performance deficits on the Luria Battery. The implications of these findings, if confirmed, are substantial on issues of criminal responsibility, sentencing, treatment, and rehabilitation of the sex offender. Case reports of the patients studied are presented. PMID:7097186

Graber, B; Hartmann, K; Coffman, J A; Huey, C J; Golden, C J

1982-01-01

111

Catalyst assessment for upgrading short contact time SRC (solvent-refined coal) to low-sulfur boiler fuels  

SciTech Connect

Of nine catalysts tested in a fixed-bed pilot unit for upgrading a 50% West Kentucky SRC recycle solvent blend, best desulfurization and deoxygenation activities were obtained with proprietary catalysts, Mobil HCL-2 and HCL-3, American Cyanamid's commercial HDS-1443, and Harshaw's commercial 618X catalyst. The activities depended in part on the presence of macropores. The best Conradson carbon residue reduction was obtained with Mobil HCL-2 and HCL-3, and with Amoco'/s developmental catalyst Amocat 1B. The highest polar asphaltene conversion was obtained with Amocat 1B and HDS-1443. The lowest hydrogen consumption as a function of total liquid product sulfur content occurred with HCL-2, HDS-1443, and Amocat 1A. An aging run with Amocat 1A was operated smoothly for 15 days at 2000 psig and 775/sup 0/F, and then terminated owing to incipient reactor plugging; a simple deactivation equation correctly predicted the degree of desulfurization with time on stream, which was equivalent to a 2/sup 0/ to 3/sup 0/F/day temperature rise for maintaining constant product sulfur levels. The deposits formed on the catalysts were analyzed.

Shih, S.S.; Angevine, P.J.; Heck, R.H.; Sawruk, S.

1980-01-01

112

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

PubMed

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

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

2014-10-01

113

Retrospective dosimetry: dose evaluation using unheated and heated quartz from a radioactive waste storage building.  

PubMed

In the assessment of dose received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using heated materials such as household ceramics and bricks. However, unheated materials such as mortar and concrete are more commonly found in industrial sites and particularly in nuclear installations. These materials contain natural dosemeters such as quartz, which usually is less sensitive than its heated counterpart. The potential of quartz extracted from mortar in a wall of a low-level radioactive-waste storage facility containing distributed sources of 60Co and 137Cs has been investigated. Dose-depth proliles based on small aliquots and single grains from the quartz extracted from the mortar samples are reported here. These are compared with results from heated quartz and polymineral fine grains extracted from an adjacent brick, and the integrated dose recorded by environmental TLDs. PMID:12382805

Jain, M; Břtter-Jensen, L; Murray, A S; Jungner, H

2002-01-01

114

Recalibration of indium foil for personnel screening in criticality accidents.  

PubMed

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

Takada, C; Tsujimura, N; Mikami, S

2011-03-01

115

Characterisation of neutron fields at Cernavoda NPP.  

PubMed

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

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

2013-04-01

116

EPR/alanine pellets with low Gd content for neutron dosimetry.  

PubMed

This paper reports on results obtained by electron paramagnetic resonance (EPR) measurements and Monte Carlo (MC) simulation on a blend of alanine added with low content of gadolinium oxide (5 % by weight) to improve the sensitivity to thermal neutron without excessively affecting tissue equivalence. The sensitivity is enhanced by this doping procedure of more an order of magnitude. The results are compared with those obtained with the addition of boric acid (50 % by weight) where boron is in its natural isotopic composition in order to produce low-cost EPR dosemeters. The gadolinium addition influences neutron sensitivity more than the boron addition. The presence of additives does not substantially change the fading of the EPR signal induced by neutrons. The MC simulations agree the experimental results in case of gadolinium addition. PMID:24262924

Marrale, M; Brai, M; Longo, A; Panzeca, S; Carlino, A; Tranchina, L; Tomarchio, E; Parlato, A; Buttafava, A; Dondi, D; Zeffiro, A

2014-10-01

117

Study on quality control parameters of a TLD system for individual monitoring.  

PubMed

This work intends to identify and follow up quality control parameters important for the general improvement of our thermoluminescence dosemeter (TLD) system for Individual Monitoring that is currently preparing its accreditation according to the EN ISO/IEC 17025 Standard. A retrospective analysis of the readers' start-up tests revealed an eventual variation of parameters, like the high voltage, which may affect the light collecting system, and hence the TL dose results. This was investigated and although the high voltage requires a careful look, the stability and reproducibility of the TLD system was ascertained by the results of quality control procedures. As a consequence of this work, the start-up procedure was modified and the warning levels used for the start-up daily tests of the readers were derived from a more realistic approach. PMID:15367763

Alves, J G; Montezuma, R; Margo, O; Santos, L

2004-01-01

118

Monoenergetic fast neutron reference fields: II. Field characterization  

NASA Astrophysics Data System (ADS)

Monoenergetic neutron reference fields are required for the calibration of neutron detectors and dosemeters for various applications ranging from nuclear physics and nuclear data measurements to radiation protection. In a series of two separate publications the metrological aspects of the production and measurement of fast neutrons are reviewed. In the first part, requirements for the nuclear reactions used to produce neutron fields as well as methods for target characterization and the general layout of reference facilities were discussed. This second part focuses on the most important techniques for field characterization and includes the determination of the neutron fluence as well as the spectral neutron distribution and the determination of the fluence of contaminating photons. The measurements are usually carried out relative to reference cross sections which are reviewed in a separate contribution, but for certain conditions 'absolute' methods for neutron measurements can be used which are directly traceable to the international system of units (SI).

Nolte, Ralf; Thomas, David J.

2011-12-01

119

Monoenergetic fast neutron reference fields: I. Neutron production  

NASA Astrophysics Data System (ADS)

Monoenergetic neutron reference fields are required for the investigation of the energy-dependent response and the calibration of neutron detectors and dosemeters for various applications ranging from nuclear physics and nuclear data measurements to radiation protection. In a series of two separate publications the metrological aspects of the production and the measurement of fast neutrons are reviewed. In this first part, requirements for the nuclear reaction used to produce the neutron field as well as methods for target characterization and the general layout of reference facilities are discussed. The second part will focus on the most important techniques for field characterization. This includes the determination of the neutron fluence as well as the spectral neutron distribution and the determination of the fluence of contaminating photons.

Nolte, Ralf; Thomas, David J.

2011-12-01

120

Argentine intercomparison programme for personal dosimetry.  

PubMed

An Intercomparison Programme is being carried out in Argentina for individual monitoring services. The programme was designed to test, on a voluntary basis, the performance of the laboratories that provide individual monitoring services for X and gamma radiation fields in the range from low-level dose up to 100 mSv. Irradiations were performed in full accordance with ISO 4037-3 recommendations by the Regional Reference Centre for Dosimetry (CRRD), belonging to Atomic Energy Commission (CNEA) and the Physical Dosimetry Laboratory of the Nuclear Regulatory Authority (ARN). At the same time, several items have been asked to each participant pertaining to the action range, the detectors' characteristics, the laboratory procedures, the existence of an algorithm and its use for the dosemeter evaluation. In this study the evolution of the laboratories' performance throughout the programme, based on ISO 14146 acceptance criteria, is shown. PMID:17848382

Gregori, B N; Papadópulos, S B; Saraví, M; Kunst, J J

2007-01-01

121

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

PubMed

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

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

2014-10-01

122

Dose distributions in phantoms irradiated in thermal columns of two different nuclear reactors.  

PubMed

In-phantom dosimetry studies have been carried out at the thermal columns of a thermal- and a fast-nuclear reactor for investigating: (a) the spatial distribution of the gamma dose and the thermal neutron fluence and (b) the accuracy at which the boron concentration should be estimated in an explanted organ of a boron neutron capture therapy patient. The phantom was a cylinder (11 cm in diameter and 12 cm in height) of tissue-equivalent gel. Dose images were acquired with gel dosemeters across the axial section of the phantom. The thermal neutron fluence rate was measured with activation foils in a few positions of this phantom. Dose and fluence rate profiles were also calculated with Monte Carlo simulations. The trend of these profiles do not show significant differences for the thermal columns considered in this work. PMID:17576652

Gambarini, G; Agosteo, S; Altieri, S; Bortolussi, S; Carrara, M; Gay, S; Nava, E; Petrovich, C; Rosi, G; Valente, M

2007-01-01

123

Water equivalent plastic scintillation detectors in radiation therapy.  

PubMed

A review of the dosimetric characteristics and properties of plastic scintillation detectors for use in radiation therapy is presented. The detectors show many desirable qualities when exposed to megavoltage photon and electron beams, including water equivalence, energy independence, reproducibility, dose linearity, resistance to radiation damage and near temperature independence. These detectors do not require the usual conversion and/or correction factors used to convert the readings from common dosemeters to absorbed dose. Due to their small detecting volume, plastic scintillation detectors exhibit excellent spatial resolution. Detector performance, in certain specific cases, can be affected by radiation-induced light arising in the optical fibres that carry the scintillator signal to a photodetector. While this effect is negligible for photon beams, it may not be ignored for electron beams and needs to be accounted for. PMID:16882685

Beddar, A S

2006-01-01

124

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

PubMed

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

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

2013-01-01

125

Simulated workplace neutron fields  

NASA Astrophysics Data System (ADS)

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.

Lacoste, V.; Taylor, G.; Röttger, S.

2011-12-01

126

Thermal neutron calibration channel at LNMRI/IRD.  

PubMed

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

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

2014-10-01

127

Spectra and Neutron Dosimetry Inside a PET Cyclotron Vault Room  

NASA Astrophysics Data System (ADS)

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/?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.

Vega-Carrillo, Héctor René; Méndez, Roberto; Ińiguez, María Pilar; Martí-Climent, Joseph; Peńuelas, Iván; Barquero, Raquel

2006-09-01

128

Liulin-type spectrometry-dosimetry instruments.  

PubMed

The main purpose of Liulin-type spectrometry-dosimetry instruments (LSDIs) is cosmic radiation monitoring at the workplaces. An LSDI functionally is a low mass, low power consumption or battery-operated dosemeter. LSDIs were calibrated in a wide range of radiation fields, including radiation sources, proton and heavy-ion accelerators and CERN-EC high-energy reference field. Since 2000, LSDIs have been used in the scientific programmes of four manned space flights on the American Laboratory and ESA Columbus modules and on the Russian segment of the International Space Station, one Moon spacecraft and three spacecraft around the Earth, one rocket, two balloons and many aircraft flights. In addition to relative low price, LSDIs have proved their ability to qualify the radiation field on the ground and on the above-mentioned carriers. PMID:21177270

Dachev, Ts; Dimitrov, Pl; Tomov, B; Matviichuk, Yu; Spurny, F; Ploc, O; Brabcova, K; Jadrnickova, I

2011-03-01

129

Tissue-equivalent TL sheet dosimetry system for X- and gamma-ray dose mapping.  

PubMed

To measure dose distribution for X- and gamma rays simply and accurately, a tissue-equivalent thermoluminescent (TL) sheet-type dosemeter and reader system were developed. The TL sheet is composed of LiF:Mg,Cu,P and ETFE polymer, and the thickness is 0.2 mm. For the TL reading, a square heating plate, 20 cm on each side, was developed, and the temperature distribution was measured with an infrared thermal imaging camera. As a result, linearity within 2% and the homogeneity within 3% were confirmed. The TL signal emitted is detected using a CCD camera and displayed as a spatial dose distribution. Irradiation using synchrotron radiation between 10 and 100 keV and (60)Co gamma rays showed that the TL sheet dosimetry system was promising for radiation dose mapping for various purposes. PMID:16614090

Nariyama, N; Konnai, A; Ohnishi, S; Odano, N; Yamaji, A; Ozasa, N; Ishikawa, Y

2006-01-01

130

Spectra and Neutron Dosimetry Inside a PET Cyclotron Vault Room  

SciTech Connect

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.

Vega-Carrillo, Hector Rene [Unidades Academicas: Estudios Nucleares e Ing. Electrica. Universidad Autonoma de Zacatecas, A.P. 336, 98000 Zacatecas, Zac. Mexico (Mexico); Mendez, Roberto [Universidad Europea Miguel de Cervantes, Valladolid (Spain); Iniguez, Maria Pilar [Facultad de Ciencias de la Universidad de Valladolid, Valladolid (Spain); Marti-Climent, Joseph; Penuelas, Ivan [Servicio de Medicina Nuclear, Clinica Universitaria de la Universidad de Navarra (Spain); Barquero, Raquel [Hospital Universitario Rio Hortega, Valladolid (Spain)

2006-09-08

131

Review of retrospective dosimetry techniques for external ionising radiation exposures.  

PubMed

The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements. PMID:21183550

Ainsbury, E A; Bakhanova, E; Barquinero, J F; Brai, M; Chumak, V; Correcher, V; Darroudi, F; Fattibene, P; Gruel, G; Guclu, I; Horn, S; Jaworska, A; Kulka, U; Lindholm, C; Lloyd, D; Longo, A; Marrale, M; Monteiro Gil, O; Oestreicher, U; Pajic, J; Rakic, B; Romm, H; Trompier, F; Veronese, I; Voisin, P; Vral, A; Whitehouse, C A; Wieser, A; Woda, C; Wojcik, A; Rothkamm, K

2011-11-01

132

Dose response of xylitol and sorbitol for EPR retrospective dosimetry with applications to chewing gum.  

PubMed

The purpose of this investigation was to study the radiation-induced electron paramagnetic resonance signal in sweeteners xylitol and sorbitol for use in retrospective dosimetry. For both sweeteners and chewing gum, the signal changed at an interval of 1-84 d after irradiation with minimal changes after 4-8 d. A dependence on storage conditions was noticed and the exposure of the samples to light and humidity was therefore minimised. Both the xylitol and sorbitol signals showed linearity with dose in the measured dose interval, 0-20 Gy. The dose-response measurements for the chewing gum resulted in a decision threshold of 0.38 Gy and a detection limit of 0.78 Gy. A blind test illustrated the possibility of using chewing gums as a retrospective dosemeter with an uncertainty in the dose determination of 0.17 Gy (1 SD). PMID:22908355

Israelsson, A; Gustafsson, H; Lund, E

2013-04-01

133

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

PubMed

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

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

2012-08-01

134

Evaluation of the effects of scattered radiation on dosimeter calibration in a calibration range.  

PubMed

ISO standard 4037 specifies limits for scattered radiation for "gamma reference radiation" for the calibration of "protection-level dosemeters and rate dosemeters." More specifically, it specifies that scattered radiation should contribute less than 5% to the total exposure rate for source-center-to-dosimeter-center distances (henceforth called downrange distances) over which dosimeters are calibrated. In a previous paper by the authors, the results of an MCNP analysis of a calibration range with a Cs irradiator (henceforth called Cs calibration range) were reported. In that paper, simulations of the singly differential photon fluence rate (i.e., flux) energy spectra (henceforth called photon flux energy spectra) from the Cs (an ISO standard 4037 gamma reference radiation) irradiator were reported. In that paper, the spectra were examined to determine the contribution of scattered photons to the exposure rate in the Cs calibration range for various downrange distances. In this paper, the simulations of the photon flux energy spectra for the Cs irradiator photons for various downrange distances are convolved with response functions, creating an ideal exposure meter and two commercially available ion chamber survey meters, in order to predict the meters' response rates versus downrange distance. The simulated response rates indicate that the Cs calibration range satisfies an operational check of the contribution of scattered radiation to the exposure rate that is specified in the ISO standard 4037, although as shown in the previous paper by the authors, the Cs calibration range does not satisfy the ISO standard 4037 specification that scattered radiation should contribute less than 5% to the total exposure rate for downrange distances over which dosimeters are calibrated. The ISO standard 4037 operational check is that the measured exposure rate varies from an inverse square dependence by less than 5% for the downrange distances over which dosimeters are calibrated. PMID:23192089

Petrie, Christian M; Nimps, Ronni G; Blue, Thomas E; Herminghuysen, Kevin

2013-01-01

135

Photon energy dependence of the sensitivity of radiochromic film and comparison with silver halide film and LiF TLDs used for brachytherapy dosimetry.  

PubMed

There is a new radiochromic film, a highly uniform, thin (100-microns) detector whose sensitive layer (6 microns thick) changes from colorless to blue by dye polymerization without processing, upon exposure to ionizing radiation. Because the dose gradients around brachytherapy sources are steep, the high spatial resolution offered by film dosimetry is an advantage over other detectors such as thermoluminescent dosimeters (TLDs). This compares the photon energy dependence of the sensitivities of GafChromic film, silver halide verification film (Kodak X-Omat V Film), and lithium fluoride TLDs (Harshaw), over the photon energy range 28 keV to 1.7 MeV, which is of interest in brachytherapy. Sensitivity of the radiochromic film is observed to decrease by about 30% as effective photon energy decreases from 1710 keV (4-MV x rays) to 28 keV (60-kV x rays, 2-mm A1 filter). In contrast, the sensitivity of verification film increases by 980% and that of LiF TLDs increases by 41%. The variation of the sensitivity of radiochromic film with photon energy is considerably less than that for silver halide film and similar to that for LiF TLDs, but in the opposite direction. Radiochromic film, like LIF TLDs, does not exhibit the drastic sensitivity changes below 127 keV that silver halide film exhibits. Dose distribution in the immediate vicinity of a high activity (370 GBq) brachytherapy 192Ir source has been mapped using radiochromic film and is presented to illustrate the applicability of this new technology to brachytherapy dosimetry. PMID:1921886

Muench, P J; Meigooni, A S; Nath, R; McLaughlin, W L

1991-01-01

136

Improving neutron dosimetry using bubble detector technology  

SciTech Connect

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.

Buckner, M.A.

1993-02-01

137

Surface-modified polyblend membranes for gas separation process  

SciTech Connect

Blends of polymethyl-methacrylate (PMMA) and poly (vinylidene fluoride) (PVDF) were studied. It was found that concentration of PVDF less than 40 wt% lead to miscible systems when the membranes are cast from dimethyl sulfoxide solvent. The miscible polyblends were used as media for the separation of a 50:50 carbon dioxide:methane gas mixture. The measurements of transport properties were made using a Harshaw permeability cell with FTIR detection. Both the transient and steady state permeabilities of carbon dioxide and methane were determined. Low pressures of the gas mixture were used to minimize any artifacts arising from plasticization effects due to carbon dioxide sorption. The results showed that the separation factor, the ratio of the measured permeabilities of carbon dioxide and methane, was decreased by increasing the content of PVDF. Thermodynamic concepts were applied to predict the permeabilities of carbon dioxide and methane in pure amorphous PVDF and the polyblends. Surface characterization of the polymer blends, prior to surface modification, was done using contact angle, ESCA and ISS measurements. Acid hydrolysis of the surface region to form poly (methacrylic acid) (PMAA) was carried out using dilute (65 vol%) sulfuric acid. Different reagents for post-treatment of the hydrolyzed membranes led to different surface structures and morphologies, that dominated the final separation and permeabilities of both gases. Water swelled the surface layer, and caused defects after it was removed, that deteriorated the separation efficiency of the membranes. Isopropyl alcohol post-treatment led to a denser surface layer and increased the separation efficiency. FTIR-ATR, density measurements, and optical and electron microscopies were utilized to help interpret the transport property data.

Yang, T.

1989-01-01

138

Practical experiences with the synthesis of [11C]CH3I through gas phase iodination reaction using a TRACERlabFXC synthesis module.  

PubMed

The results of [(11)C]CH(3)I synthesis through hydrogen gas reduction of [(11)C]CO(2) on different nickel catalysts (HARSHAW-nickel, SHIMALITE-nickel, nickel on silica/alumina, nickel nanosize 99.99%) followed by gas phase iodination using a TRACERlab FX(C) synthesis unit are reported. Further reaction parameters such as furnace temperatures, flow rate of hydrogen gas and reduction time were optimized. It was found that reduction of [(11)C]CO(2) proceeded in 28-83% yield depending on the nickel catalyst and temperature. The gas phase iodination (methane conversion) gave 31-62% of [(11)C]CH(3)I depending on temperature and amount of iodine in the iodine furnace. [(11)C]CH(3)I was used for heteroatom methylation reactions exemplified by a piperazine and a phenol (1 and 3). The specific activity of the (11)C-labelled products 2 and 4 was determined after HPLC purification and solid-phase extraction. Compounds 2 and 4 were obtained in 8-14% radiochemical yield (decay-corrected, based upon trapped [(11)C]CH(4)) within 30 min. The specific activity was determined to be in the range of 20-30 GBq/mumol at the end-of-synthesis. Nickel catalyst nanosize was found to be superior compared with other Ni catalysts tested. The relatively low specific activity may be mainly due to carbon contaminations originating from the long copper tubing (500 m) between the cyclotron and the radiochemistry facility. PMID:17683943

Kniess, Torsten; Rode, Katrin; Wuest, Frank

2008-04-01

139

Comparison of different PADC materials for neutron dosimetry.  

PubMed

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

Mayer, S; Boschung, M

2014-10-01

140

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

PubMed

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

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

2014-10-01

141

Neutron measurements in a Varian 2,100C LINAC facility using a Bonner sphere system based on passive gold activation detectors.  

PubMed

The use of high-energy linear electron accelerators (LINACs) for medical cancer treatments is widespread on an international scale. The associated bremsstrahlung X rays may produce neutrons as a result of subsequent photonuclear reactions with the different materials constituting the accelerator head. The generated neutron field is highly variable and depends strongly on the beam energy, on the accelerator shielding, on the flattering filter as well as on the movable collimators (jaws) design and on the irradiation field geometry. An estimate of this photoneutron component is, thus, of practical interest to quantify the radiological risk for the working staff and patients. Due to high frequency electromagnetic fields, and also to the presence of abundant leaked and scattered photons in these installations, measurements of the corresponding neutron fields by active dosemeters are extremely difficult. A modified version of the Bonner sphere system, based on passive gold activation detectors, has been used to perform neutron measurements at two points in a Varian 2,100C LINAC facility. A home-made unfolding procedure (CDM) has been utilised to determine the neutron spectra present at the measurement points. Results indicate that the giant dipole resonance process is the most adequate model to explain neutron production in the LINAC and that a thermal component is present at the measurement points. PMID:17525060

Fernández, F; Domingo, C; Amgarou, K; Castelo, J; Bouassoule, T; Garcia, M J; Luguera, E

2007-01-01

142

Organ/Tissue absorbed doses measured with a human phantom torso in the 9th Shuttle-Mir Mission (STS-91).  

PubMed

Organ/Tissue absorbed doses were measured with a life-size human phantom torso in the 9th Shuttle/Mir Mission (STS-91) from June 2 to 12, 1998. This is the first attempt to measure directly organ/tissue doses over a whole human body in space. The absorbed dose was measured by combination of two integrating detectors: thermo- luminescent dosemeter of Mg2SiO4: Tb (TDMS) and plastic nuclear track detector (PNTD). Both detectors were calibrated on ground using high-energy charged-particle beams. The detectors were packed in 59 cases of tissue-equivalent resin; and put into the positions of radiologically important organs and tissues in the phantom. Efficiency reductions of TDMS for high-LET particles were corrected based on the LET-differential particle fluence of space radiation measured with PNTDs. The accumulated absorbed doses during this 9.8-days mission at low-earth orbit (400 km x 51.6 degrees) ranged from 1.6 mGy at colon to 2.6 mGy at bone surface (shoulder) with a variation factor of 1.6. The absorbed doses at some internal organs were higher than the skin dose. This fact is important from the viewpoint of radiological protection for astronauts. PMID:11543317

Yasuda, H; Komiyama, T; Fujitaka, K

1999-09-01

143

Preparation and thermoluminescence properties of aluminium oxide doped with europium.  

PubMed

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

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

2002-01-01

144

Glow curve analysis applied to the discrimination of X ray versus proton irradiation.  

PubMed

Three types of thermoluminescence dosemeters (TLDs): LiF:Mg,Ti (TLD-100), CaF2:Tm (TLD-300), and alpha-Al2O3:C (TLD-500), were investigated for their glow curve response to separate X ray and proton irradiations. The glow curve structure for each individual TLD's exposure to the X ray and proton irradiations was analysed and compared. Distinguishable differences between the glow curve structure characteristic of each type of radiation were observed. The proton TLD-100 glow curve has revealed a complex high-temperature peak structure that was used for the proton/X ray discrimination algorithm. Proton irradiation of TLD-300 resulted in an apparent switch in the relative heights of peaks 3 and 5 as compared to X ray. In TLD-500, proton irradiation produced a more subtle difference in the glow curve with an increase in the ratio between high- and low-temperature peaks. Results demonstrate promising differences in glow curve structure present allowing for discrimination between X ray and proton radiation field exposures. PMID:12382714

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

2002-01-01

145

Measurements of X ray absorbed doses to dental patients in two dental X ray units in Nigeria.  

PubMed

Measurements of absorbed doses from radiographic examinations to various anatomical sites in the head and neck of patients with an average age of 45 years using intra-oral dental radiography have been carried out. LiF (TLD-100) dosemeters were used for the measurements of the absorbed dose. The measured absorbed doses to the various anatomical sites in the two units are reported, discussed and compared with results from the literature. Quality control measurements were also performed using a Victoreen quality control test device on the X ray units. The tube voltage accuracies for the two units were found to be within acceptable limits (less than +/- 10%). On the other hand the exposure time accuracies for these units have large deviations (>20%). These results and those that have been reported in the literature may be an indication that high patient doses are common in most dental X ray centres and countries. As a result of this, regular compliance and performance checks of dental diagnostic X ray equipment are essential in order to ensure proper performance and to minimise unnecessary patient and operator doses. PMID:12474946

Ogundaret, F O; Oni, O M; Balogun, F A

2002-01-01

146

Geant4 simulation of the CERN-EU high-energy reference field (CERF) facility.  

PubMed

The CERN-EU high-energy reference field facility is used for testing and calibrating both active and passive radiation dosemeters for radiation protection applications in space and aviation. Through a combination of a primary particle beam, target and a suitable designed shielding configuration, the facility is able to reproduce the neutron component of the high altitude radiation field relevant to the jet aviation industry. Simulations of the facility using the GEANT4 (GEometry ANd Tracking) toolkit provide an improved understanding of the neutron particle fluence as well as the particle fluence of other radiation components present. The secondary particle fluence as a function of the primary particle fluence incident on the target and the associated dose equivalent rates were determined at the 20 designated irradiation positions available at the facility. Comparisons of the simulated results with previously published simulations obtained using the FLUKA Monte Carlo code, as well as with experimental results of the neutron fluence obtained with a Bonner sphere spectrometer, are made. PMID:20511404

Prokopovich, D A; Reinhard, M I; Cornelius, I M; Rosenfeld, A B

2010-09-01

147

Strict X-ray beam collimation for facial bones examination can increase lens exposure  

PubMed Central

Objectives It is well accepted that collimation is a cost-effective dose-reducing tool for X-ray examinations. This phantom-based study investigated the impact of X-ray beam collimation on radiation dose to the lenses of the eyes and thyroid along with the effect on image quality in facial bone radiography. Methods A three-view series (occipitomental, occipitomental 30 and lateral) was investigated, and radiation doses to the lenses and thyroid were measured using an Unfors dosemeter. Images were assessed by six experienced observers using a visual grading analysis and a total of 5400 observations were made. Results Strict collimation significantly (p<0.0001) reduced the radiation dose to the lenses of the eyes and thyroid when using a fixed projection-specific exposure. With a variable exposure technique (fixed exit dose, to simulate the behaviour of an automatic exposure control), while strict collimation was again shown to reduce thyroid dose, higher lens doses were demonstrated when compared with larger fields of exposure. Image quality was found to significantly improve using strict collimation, with observer preference being demonstrated using visual grading characteristic curves. Conclusion The complexities of optimising radiographic techniques have been shown and the data presented emphasise the importance of examining dose-reducing strategies in a comprehensive way. PMID:22374279

Powys, R; Robinson, J; Kench, P L; Ryan, J; Brennan, P C

2012-01-01

148

Assessing occupational and domestic ELF magnetic field exposure in the uk adult brain tumour study: results of a feasibility study.  

PubMed

The feasibility of measuring exposure to extremely low frequency magnetic fields (ELF MF) in the UK Adult Brain Tumour Study (UKABTS) was examined. During the study, 81 individuals and 30 companies were approached with 79 individuals and 25 companies agreeing to participate. Exposure data were collected using EMDEX II dosemeters worn by the participants for 3-4 consecutive days. Data were collected over a total of 321 d, including non-occupational periods. The results showed occupational exposure to be the main determinant of overall exposure. Moderate to strong correlations were found between arithmetic mean exposure and all other metrics with the possible exception of maximum exposure. Significant differences in exposure were found between job categories with large variability in certain categories. Highest average exposures were found for security officers (arithmetic mean, AM: 0.78 micro T), secretaries (AM: 0.48 micro T) and dentists (AM: 0.42 micro T). Welding and working near high-voltage power lines were associated with elevated exposure. In summary, acceptably precise measures of ELF MF exposure are feasible at relatively moderate cost. The results were used to develop a protocol for data collection from subjects in the UKABTS. PMID:15031444

van Tongeren, Martie; Mee, Terry; Whatmough, Pamela; Broad, Lisa; Maslanyj, Myron; Allen, Stuart; Muir, Ken; McKinney, Patricia

2004-01-01

149

Synthesis and characterisation of BaSo4:Eu thermoluminescence phosphor.  

PubMed

Polycrystalline powder samples of BaSO(4) doped with Eu(2+) were prepared by solid-state reaction in different reducing atmospheres. Photoluminescence (PL), thermoluminescence (TL), TL kinetic and dosimetric studies have been carried out in this phosphor. The TL glow curve of BaSO(4):Eu(2+) showed only a single peak at 513 K unlike other phosphors and the TL intensity is about three to four times higher than that of CaSO(4):Dy, which is currently used as the radiation dosemeter for personnel monitoring in India. The TL dose response of the phosphor was found to be linear up to the dose range of 10(3) Gy beyond which saturation sets in. PL and TL spectra showed the characteristic emission of Eu(2+) ion. The TL parameters such as trap depth (E) or the energy required to release the electron or hole from the trap, frequency factor (s) and the order of kinetics (b) are determined by different methods such as isothermal decay, initial rise and variable heating rate. PMID:22223718

Annalakshmi, O; Jose, M T; Madhusoodanan, U

2012-06-01

150

Dosimetry of BNCT beams with novel thermoluminescent detectors.  

PubMed

In the dosimetry of boron neutron capture therapy (BNCT) beams, thermoluminescent (TL) detectors are typically applied in phantom measurements to determine the spatial distribution of the gamma ray and neutron dose. Pairs of 6LiF and 7LiF are applied to discriminate between the thermal neutron and gamma ray field components, exploiting the high cross section for (n,alpha) reaction of 6Li. At the Institute of Nuclear Physics (INP) in Kraków (Poland) a prototype TL-based measuring set has been constructed and tested. This set consists of a miniature TL detector (of 2 mm diameter and 0.4 mm thickness) placed inside a miniature container made of non-thermoluminescent 6LiF. The outer dimensions of the set are 4.5 mm diameter and 1.4 mm thickness, enabling its application in place of a thermoluminescence dosemeter pellet in typical phantoms. The detector sets were tested in the BNCT beam of the Studsvik reactor. By exploiting the ratio of TL signals of the unshielded and shielded detectors, it was possible to estimate the contributions of the thermal and epithermal components of the neutron field. PMID:15353719

Bilski, P; Budzanowski, M; Ochab, E; Olko, P; Czopyk, ?

2004-01-01

151

Dose reduction in a paediatric X-ray department following optimization of radiographic technique.  

PubMed

A survey of radiation doses to children from diagnostic radiography has been carried out in a dedicated paediatric X-ray room. Entrance surface dose (ESD) and dose-area product (DAP) per radiograph were simultaneously measured with thermoluminescent dosemeters (TLDs) and a DAP meter to provide mean dose values for separate age ranges. Results of ESD and DAP were lower than the mean values from other UK studies for all ages and radiographs, except for the infant pelvis AP radiograph. Comparison of ESD and radiographic technique with CEC quality criteria highlighted a need for reduction of dose to infants and implied an increase in tube filtration might overcome the limitations of the room's three-phase, 12-pulse generator, allowing higher tube potentials to be used on infants. Additional tube filtration of 3 mmA1 was installed following assessment of dose reduction and image quality with test objects and phantoms, and confirmation from the paediatric radiologist that clinical image quality was not-significantly altered. The tube potential was increased from 50 to 56 kVp for the infant pelvis AP radiograph. The resulting ESD and effective dose fell by 51% and 38%, respectively. The CEC quality criteria have proved useful as a benchmark against which technique in X-ray departments can be compared, and as such are a useful tool for optimizing radiographic technique and reducing patient dose. PMID:9828798

Mooney, R; Thomas, P S

1998-08-01

152

Neutron dose distribution at the GSI fragment separator.  

PubMed

GSI is operating a facility for the production of rare isotopes. Nuclei are produced by fragmentation or fission of the impinging heavy ions with energies of approximately 1 GeV per nucleon. The major part of the primary beam and the produced nuclei is deposited in the components of the Fragment Separator (FRS) and generates neutron radiation. Thermoluminescence dosemeters (TLDs) (6LiF/7LiF pairs in PE spheres) were exposed in neutron fields produced by uranium beams with energies between 100 and 1000 MeV per nucleon during an irradiation period in the year 2002. Two-dimensional dose distributions are obtained using these TL measurements in combination with model calculations. The applied model describes the dose distribution as a superposition of dose patterns of 20 single sources equally distributed along the FRS. The single source distribution is based on a measured double differential neutron distribution for a 1 GeV per nucleon uranium beam. PMID:15353740

Fehrenbacher, G; Festag, J G

2004-01-01

153

Effective dose span of ten different cone beam CT devices  

PubMed Central

Objectives: Evaluation and reduction of dose are important issues. Since cone beam CT (CBCT) has been established now not just in dentistry, the number of acquired examinations continues to rise. Unfortunately, it is very difficult to compare the doses of available devices on the market owing to different exposition parameters, volumes and geometries. The aim of this study was to evaluate the spans of effective doses (EDs) of ten different CBCT devices. Methods: 48 thermoluminescent dosemeters were placed in 24 sites in a RANDO® head phantom. Protocols with lowest exposition parameters and protocols with highest exposition parameters were performed for each of the ten devices. The ED was calculated from the measured energy doses according to the International Commission on Radiological Protection 2007 recommendations for each protocol and device, and the statistical values were evaluated afterwards. Results: The calculation of the ED resulted in values between 17.2?µSv and 396?µSv for the ten devices. The mean values for protocols with lowest and highest exposition parameters were 31.6?µSv and 209?µSv, respectively. Conclusions: It was not the aim of this study to evaluate the image quality depending on different exposition parameters but to define the spans of EDs in which different CBCT devices work. There is a wide span of ED for different CBCT devices depending on the selected exposition parameters, required spatial resolution and many other factors. PMID:23584925

Rottke, D; Patzelt, S; Poxleitner, P; Schulze, D

2013-01-01

154

Study of the impact of artificial articulations on the dose distribution under medical irradiation  

NASA Astrophysics Data System (ADS)

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.

Buffard, E.; Gschwind, R.; Makovicka, L.; Martin, E.; Meunier, C.; David, C.

2005-02-01

155

Comparison of radiation doses between newborns and 6-y-old children undergoing head, chest and abdominal CT examinations: a phantom study.  

PubMed

Radiation doses in paediatric computed tomography (CT) were investigated for various types of recent CT scanners with newborn and 6-y-old phantoms in which silicon-photodiode dosemeters were implanted at various organ positions. In the head, chest and abdominal CT for the newborn phantom, doses for organs within the scan region were 21-40, 3-8 and 3-12 mGy, respectively. The corresponding doses for the child phantom were 20-37, 2-11 and 4-17 mGy, respectively. In the head, chest and abdominal CT, the effective doses were respectively 2.1-3.3, 2.0-6.0 and 2.2-10.0 mSv for the newborn, and 1.0-2.0, 1.2-6.6 and 2.9-11.8 mSv for the child. Radiation doses for the newborn were at the same levels as those for the child, excepting effective doses in head CT for the newborn, which were 1.8 times higher than those for the child. PMID:22645383

Sugimoto, Naruto; Aoyama, Takahiko; Koyama, Shuji; Yamauchi-Kawaura, Chiyo; Fujii, Keisuke

2013-01-01

156

Natural radiation exposure in a municipality of the Brazilian Sertao  

SciTech Connect

Sixty-seven thermoluminescent dosemeters (TLDs) were distributed to the inhabitants of a Brazilian municipality located in the semi-arid inland (Sertao) of the state of Rio Grande do Norte. All the TLDs were exposed for 180 d in bedrooms or in living areas of the selected buildings and eventually returned to the authors` laboratory in italy. Radiological measurements gave a range of 32-330 nGy h{sup -1}, an arithmetic mean of 107 {+-} 47 nGy h{sup -1}, and a geometric mean of 99 nGy h{sup -1}. This last value corresponds to an annual indoor effective dose equivalent of 425 {mu}Sv. Concentrations of primordial radionuclides in some samples of building material, soil, and rock collected in the aformentioned territory were analytically determined by gamma spectrometer. The relatively high content of {sup 226}Ra (98.5 {+-} 12 Bq kg{sup -1}), {sup 232}Th (252.5 {+-} 47 Bq kg{sup -1}), and {sup 40}K (1533 {+-} 169 Bq kg{sup -1}) in bedrock is probably responsible for the elevated {lambda}-radiation environment of that municipality. 12 refs., 1 fig., 2 tab.

Malanca, A. [UFRN, Natal (Brazil)] [UFRN, Natal (Brazil); Gaidolfi, L. [Settore Fisico-Ambientale, Piacenza (Italy)] [Settore Fisico-Ambientale, Piacenza (Italy)

1996-08-01

157

Fibre remote optoelectronic gamma dosimetry based on optically stimulated luminescence of Al2O3:C.  

PubMed

Optically stimulated luminescence dosimetry (OSL-D) used in conjunction with fibre optics enables a remote measurement of dose, for the purpose of radioprotection in the nuclear industry and in medicine (radiology, radiotherapy). Alumina OSL crystals are used because of their low Z, low fading and optical transparency, which improves the sensitivity. An optoelectronic portable dosemeter has been designed and tested that shows a dose detection of 50 microGy with a 20 metre-long fibre. Following irradiation, all trapped electrons are released under light stimulation while the OSL is integrated to provide dose-equivalent measurements. A compensation technique is designed with the help of the MCNP4b code, so that both angular and photon energy characteristics comply with international standards (CEI 61066) for photon dose equivalent Hp(10). Two sensors are described that allow measurements over a wide solid angle (95% of 4piSr), for photon energies ranging from 15 keV to 3 MeV. PMID:12382872

Ranchoux, G; Magne, S; Bouvet, J P; Ferdinand, P

2002-01-01

158

The MATROSHKA Facility - History and science overview  

NASA Astrophysics Data System (ADS)

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

Reitz, G.; Berger, T.

159

Tests of shielding effectiveness of Kevlar and Nextel onboard the International Space Station and the Foton-M3 capsule.  

PubMed

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

Pugliese, M; Bengin, V; Casolino, M; Roca, V; Zanini, A; Durante, M

2010-08-01

160

Automation of film densitometry for application in personal monitoring.  

PubMed

In this research work, a semi-automatic densitometry system has been developed for large-scale monitoring services by use of film badge dosemeters. The system consists of a charge-coupled device (CCD)-based scanner that can scan optical densities (ODs) up to 4.2, a computer vision algorithm to improve the quality of digitised films and an analyser program to calculate the necessary information, e.g. the mean OD of region of interest and radiation doses. For calibration of the system, two reference films were used. The Microtek scanner International Color Consortium (ICC) profiler is applied for determining the colour attributes of the scanner accurately and a reference of the density step tablet, Bundesanstalt für Materialforschung und-prüfung (BAM) is used for calibrating the automatic conversion of gray-level values to OD values in the range of 0.2-4.0 OD. The system contributes to achieve more objectives and reliable results. So by applying this system, we can digitise a set of 20 films at once and calculate their relative doses less than about 4 min, and meanwhile it causes to avoid disadvantages of manual process and to enhance the accuracy of dosimetry. PMID:21199823

Taheri, M; Movafeghi, A; Rastkhah, N

2011-03-01

161

Occupational radiation doses to the extremities and the eyes in interventional radiology and cardiology procedures  

PubMed Central

Objectives The aim of this study was to determine occupational dose levels in interventional radiology and cardiology procedures. Methods The study covered a sample of 25 procedures and monitored occupational dose for all laboratory personnel. Each individual wore eight thermoluminescent dosemeters next to the eyes, wrists, fingers and legs during each procedure. Radiation protection shields used in each procedure were recorded. Results The highest doses per procedure were recorded for interventionists at the left wrist (average 485 ?Sv, maximum 5239 ?Sv) and left finger (average 324 ?Sv, maximum 2877 ?Sv), whereas lower doses were recorded for the legs (average 124 ?Sv, maximum 1959 ?Sv) and the eyes (average 64 ?Sv, maximum 1129 ?Sv). Doses to the assisting nurses during the intervention were considerably lower; the highest doses were recorded at the wrists (average 26 ?Sv, maximum 41 ?Sv) and legs (average 18 ?Sv, maximum 22 ?Sv), whereas doses to the eyes were minimal (average 4 ?Sv, maximum 16 ?Sv). Occupational doses normalised to kerma area product (KAP) ranged from 11.9 to 117.3 ?Sv/1000 cGy cm2 and KAP was poorly correlated to the interventionists' extremity doses. Conclusion Calculation of the dose burden for interventionists considering the actual number of procedures performed annually revealed that dose limits for the extremities and the lenses of the eyes were not exceeded. However, there are cases in which high doses have been recorded and this can lead to exceeding the dose limits when bad practices are followed and the radiation protection tools are not properly used. PMID:21172967

Efstathopoulos, E P; Pantos, I; Andreou, M; Gkatzis, A; Carinou, E; Koukorava, C; Kelekis, N L; Brountzos, E

2011-01-01

162

NUNDO: a numerical model of a human torso phantom and its application to effective dose equivalent calculations for astronauts at the ISS.  

PubMed

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

Puchalska, Monika; Bilski, Pawel; Berger, Thomas; Hajek, Michael; Horwacik, Tomasz; Körner, Christine; Olko, Pawel; Shurshakov, Vyacheslav; Reitz, Günther

2014-11-01

163

Shielding effect of thyroid collar for digital panoramic radiography  

PubMed Central

Objectives: To evaluate the shielding effect of thyroid collar for digital panoramic radiography. Methods: 4 machines [Orthopantomograph® OP200 (Instrumentarium Dental, Tuusula, Finland), Orthophos CD (Sirona Dental Systems GmbH, Bensheim, Germany), Orthophos XG Plus (Sirona Dental Systems GmbH) and ProMax® (Planmeca Oy, Helsinki, Finland)] were used in this study. Average tissue-absorbed doses were measured using thermoluminescent dosemeter chips in an anthropomorphic phantom. Effective organ and total effective doses were derived according to the International Commission of Radiological Protection 2007 recommendations. The shielding effect of one collar in front and two collars both in front and at the back of the neck was measured. Results: The effective organ doses of the thyroid gland obtained from the 4 panoramic machines were 1.12??Sv for OP200, 2.71??Sv for Orthophos CD, 2.18??Sv for Orthophos XG plus and 2.20??Sv for ProMax, when no thyroid collar was used. When 1 collar was used in front of the neck, the effective organ doses of the thyroid gland were 1.01??Sv (9.8% reduction), 2.45??Sv (9.6% reduction), 1.76??Sv (19.3% reduction) and 1.70??Sv (22.7% reduction), respectively. Significant differences in dose reduction were found for Orthophos XG Plus and ProMax. When two collars were used, the effective organ doses of the thyroid gland were also significantly reduced for the two machines Orthophos XG Plus and ProMax. The same trend was observed in the total effective doses for the four machines. Conclusions: Wearing a thyroid collar was helpful when the direct digital panoramic imaging systems were in use, whereas for the indirect digital panoramic imaging systems, the thyroid collar did not have an extra protective effect on the thyroid gland and whole body. PMID:24005060

Han, G-S; Cheng, J-G; Li, G

2013-01-01

164

The effective dose assessment of C-arm CT in hepatic arterial embolisation therapy  

PubMed Central

Objective: To assess the effective dose of the liver C-arm computed tomography (CT) scan during hepatic arterial embolisation surgery with clinical dose–area product (DAP) data from Taiwan. Methods: The experiment used two kinds of phantoms: RANDO® Man and RANDO Woman (The Phantom Laboratory, Salem, NY), embedded with thermoluminescent dosemeters at locations according to the International Commission on Radiological Protection 103 report. The conversion factors of DAP to effective doses for males and females, respectively, were obtained. The clinical DAP data of liver C-arm CT scan during hepatic arterial embolisation surgery were collected in a hospital in Taiwan. Results: There were 125 liver transarterial embolisation therapy cases, including 94 males and 31 females, from February 2009 to June 2010. C-arm CT was used 38 times for males and 17 times for females. The corresponding average and standard deviation of clinical DAP were 61.0±6.6?Gy?cm2 and 52.2±8.3?Gy?cm2, respectively. Conclusion: The DAP of RANDO Man and RANDO Woman phantoms simply scanned by C-arm CT are much lower than that of patients. After consideration of the clinical DAP of patients, the effective doses of a liver C-arm CT scan recommended for males and females in Taiwan are 11.5±2.3?mSv and 11.3±3.0?mSv, respectively. Advances in knowledge: The conversion factors of DAP to effective doses for males and females are 0.19±0.03?mSv?Gy?1?cm?2 and 0.22±0.05?mSv?Gy?1?cm?2. Only if the actual DAP value of a patient scan is multiplied by the conversion factor can the correct effective dose be determined. PMID:23403454

Tyan, Y-S; Li, Y-Y; Ku, M-C; Huang, H-H

2013-01-01

165

Depth dose distributions measured with thermoluminescence detectors inside the anthropomorphic torso of the MATROSHKA experiment inside and outside the ISS  

NASA Astrophysics Data System (ADS)

The ESA MATROSHKA (MTR) facility was realized through the German Aerospace Center, DLR, Cologne, as main contractor, aiming for the determination of skin and organ doses within a simulated human upper torso. MTR simulates, by applying an anthropomorphic upper torso, as exact as possible an astronaut performing either an extravehicular activity (EVA) (MTR Phase 1) or an astronaut working inside the International Space Station (MTR Phase 2A). It consists of a human phantom, a Base Structure and a Carbon fibre container - simulating the astronaut‘s space suit. The phantom itself is made up 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. Over 4800 passive detectors (thermoluminescence detectors (TLDs) and plastic nuclear track detectors) constitute the radiation experiments which are beside inside the phantom also located on top the head of the phantom, in front of the belly and around the body as part of a Poncho and a Hood. In its 1st exposure phase (MTR 1: 2004 - 2005) MTR measured the depth dose distribution of an astronaut performing an EVA - mounted outside the Zvezda Module. In its 2nd exposure phase the phantom was positioned inside the ISS to monitor the radiation environment and measure the depth dose distribution in dependence on the inside shielding configurations. The majority of the TLDs provided for the determination of the depth dose distribution was provided by IFJ-PAN, ATI and DLR. Data of "combined" depth dose distribution of the three different groups will be shown for the MTR-1 exposure (outside the ISS) and the MTR-2A (inside the ISS). The discussion will focus on the difference in depth dose as well as skin dose distribution based on the different shielding thickness provided by the two experimental phases.

Berger, Thomas; Reitz, Guenther; Hajek, Michael; Bergmann, Robert; Bilski, Pawel; Puchalska, Msc. Monika

166

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)

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.

Thornberg, Charlotte

167

[Radiation exposure of health personnel and patients in the heart catheterization laboratory in during vascular brachytherapy].  

PubMed

Interventional radiological measures can lead to high radiation exposures for medical staff. In order to determine the radiation exposure to staff and patients, the resulting radiation exposures were directly measured for 52 measures at an cardiac catheterization laboratory with a new dosimetry system DIS (Direct Ion Storage). Beside the measurement of body dose behind the lead apron, measurements of radiation doses were performed in front of the lead apron and at the wrist of the physician. These measurements were taken as an approximation of the radiation exposure of the non-shielded body parts. The patients dose was estimated by placing a dosemeter close to the head of the patient and from the dose-area product. The mean value of body dose from 52 measurements for the physician behind the lead apron was 1.9 microSv per procedure with a range of 0-9 microSv. In front of the lead apron, a mean value of 53.9 microSv (3-233 microSv) per procedure was obtained. The mean value of partial body dose at the physician's wrist was determined to be 163.2 microSv (12-603 microSv) per procedure. It could be shown that measures combined with interventions lead to higher exposures compared with measures without interventions. For the medical technician, the mean value behind the lead apron was 3.9 microSv (0-58 microSv) per procedure. For the patient, a mean value of 800 microSv (119-8642 microSv) was measured close to the head. The mean dose to the skin of the patient at radiation entrance was determined to be 307 mGy (70-1190 mGy). From this data, the radiation dose per year for the physician performing 1000 measures, was determined to be 1.9 mSv/year. This is below the new dose limit of 20 mSv/year. Also the estimations for the dose to the eye lens and the hands of the physician show no conflicts with actual dose limits when obeying all radiation regulations. The results for vascular brachytherapy did not show significantly higher exposures, compared with conventional measures including interventions. PMID:12219698

Folkerts, K H; Franz, A; Kiefer, A; Hennersdorf, G

2002-06-01