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1

The use of TLD-700H dosemeters in the assessment of external doses at the former Semipalatinsk nuclear test site.  

PubMed

The joint projects performed since 1995 by the Jülich Research Centre in co-operation with the Kazakh National Nuclear Centre in the area of the former nuclear test site near Semipalatinsk, in eastern Kazakhstan, have assessed the current dose rate of the population at and around the test site, as well as determining retrospectively the dose rate of persons affected by the atmospheric tests. Measurements of the population by personal dosemeters depend on reliably wearing these dosemeters over prolonged periods of time, and of a sufficient dosemeter return. In the past, such measurements have been particularly successful whenever short wearing times were possible. This requires high sensitivity of the dosemeters. The suitability of the highly sensitive TLD material of the BICRON TLD 700H type for such personal dosimetry measurements was investigated. It was tested in practical field application at the Semipalatinsk nuclear test site in September 2000. Initial results are available from individual doses received by a group of geologists and a group of herdsmen at the test site. For the first time, the individual dose was measured directly in these population groups. Detection limits below 1 microSv permit informative measurements for wearing times of less than two weeks. Most individual doses did not arise significantly out of local fluctuations of natural background. A conservative assessment from the aspect of practical health physics yielded a mean personal dose of 0.55 microSv per day for the herdsmen, whereas the geologists received a mean personal dose of 0.45 microSv per day. For an annual exposure period of typically, about three months, the radiation dose received by the persons investigated, in addition to the natural radiation exposure, is thus well below the international limit value of 1 mSv x a(-1) for the population dose. PMID:12382756

Hill, P; Dederichs, H; Pillath, J; Schlecht, W; Hille, R; Artemev, O; Ptitskaya, L; Akhmetov, M

2002-01-01

2

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

PubMed

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

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

2007-01-01

3

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

4

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

PubMed

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

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

2006-01-01

5

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

SciTech Connect

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

Liu, J.; Sims, C.S.; Rhea, T.A. (Oak Ridge National Lab., TN (United States))

1989-08-01

6

Self-indicating radiation alert dosemeter (SIRAD).  

PubMed

In an event of a nuclear or dirty bomb explosion and a radiological accident, there is a need for self-indicating instant radiation dosemeter for monitoring radiation exposure. The self-indicating instant radiation alert dosemeter (SIRAD) is a credit card size radiation dosemeter for monitoring ionising radiation from a few hundredths of a Gray to a few Gray. It is always active and is ready to use. It needs no battery. The dosemeter develops colour instantly upon exposure, and the colour intensifies with dose. It has a colour chart so that the dose on the active element may be read by matching its colour with the chart that is printed next to it on the card. However, in this work, the dose is measured by the optical density of the element. The dosemeter cannot be reset. The response changes by <1% per degrees C from -20 to +60 degrees C. The shelf-life is >3 y at room temperature. It contains no hazardous materials. The dosemeter would meet the requirements of instantly monitoring high dose in an event of a nuclear or dirty bomb explosion or a radiation accident. PMID:16565203

Riel, Gordon K; Winters, Patrick; Patel, Gordhan; Patel, Paresh

2006-01-01

7

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

8

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

Microsoft Academic Search

The Defence Science and Technology Laboratory (Dstl) provides personal radiation dosimetry to the UK Ministry of Defence. Dstl has recently developed a dosemeter that is based on a combination of thermoluminescent and etched-track detectors. The Dstl Combined Dosemeter is capable of assessing doses due to photons, beta particles and neutrons. This paper presents the laboratory type testing results for the

L. A. Jones; R. P. Stokes

2011-01-01

9

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

PubMed

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

Jones, L A; Stokes, R P

2011-03-01

10

Comparing different error-conditions in film dosemeter evaluation.  

PubMed

In the evaluation of a film used as a personal dosemeter it may be necessary to mark the dosemeters when possible error-conditions are recognised, such as errors that have an influence on the ability to make a correct evaluation of the dose value. In this project a comparison has been carried out to examine how two individual monitoring services, IMS [National Institute of Radiation Hygiene, Denmark (NIRH) and National Research Centre for Environment and Health, Germany (GSF)], from two different EU countries mark their dosemeters. The IMS are different in size, type of customers and issuing period, but both use films as their primary dosemeters. The error-conditions examined are dosemeters exposed to moisture or light, contaminated dosemeters, films exposed outside the badge, missing filters in the badge, films inserted incorrectly in the badge and dosemeters not returned or returned too late to the IMS. The data are collected for the year 2003 where NIRH evaluated approximately 50,000 and GSF approximately 1.4 million film dosemeters. The percentage of film dosemeters is calculated for each error-condition as well as the distribution among eight different employee categories, i.e. medicine, nuclear medicine, nuclear industry, industry, radiography, laboratories, veterinary and others. It turned out, that incorrect insertion of the film in the badge was the most common error-condition observed at both IMS and that veterinarians, as the employee category, generally have the highest number of errors. NIRH has a significantly higher relative number of dosemeters in most error-conditions than GSF, which perhaps reflects that a comparison is difficult due to different systemic and methodical differences between the IMS and countries, e.g. regulations and monitoring programs etc. Also the non-existence of a common categorisation method for employee categories contributes to make a comparison like this difficult. PMID:17846026

Roed, H; Figel, M

2007-01-01

11

Ferrous-Ferric Ion exchange dosemeter.  

PubMed

In this work a three-dimensional ferrous-ferric ion exchange dosemeter is proposed and the dose response measured. The dosemeter consists of strong acid cation exchange resin beads in the H form in water. Amberlyst 15 Wet beads with a harmonic mean diameter of 0.600-0.850 mm were prepared by soaking them in an aqueous solution of ferrous ammonium sulphate to exchange ferrous ions for H(+) ions. The beads were rinsed with distilled water and packed in glass vials. Sets of samples with ferrous ion concentrations of 0.5 and 1.0 mM were dosed with 6 MV X rays from a Varian 2100C linac. The spin-lattice relaxation time constants (T1) for the samples were measured using an Apollo spectrometer (Tecmag, Houston, TX) interfaced to a 1.5 T magnet (Magnex, Abingdon, UK). Each sample had two T1 values; a long T1 at 1200 ms that did not significantly change with dose and a short T1 that ranged from 56 ms at 0 Gy to 36 ms at 100 Gy. The R1 vs. dose responses were linear with slopes of 0.066 and 0.079 s(-1) Gy(-1). PMID:16644977

Bauhs, John A; Hammer, Bruce E

2006-01-01

12

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

13

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

14

Radiochromic gel dosemeter for three-dimensional dosimetry  

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

15

NaCl as a retrospective and accident dosemeter.  

PubMed

NaCl is a cheap and widely available material. This study investigated the potential of NaCl in the form of a household salt as a retrospective and accident dosemeter using optically stimulated luminescence (OSL). Samples of the investigated household salt were stimulated using blue light of linearly modulated power. Attention was concentrated on sensitivity, dose dependence of the OSL signal, fading, optimisation of the read-out procedure and application of analytical protocols that do not require a specific calibration. A potential of NaCl as a complementary dosemeter within emergency preparedness was considered. The behaviour of the OSL signal observed was found to be favourable for dosimetry. PMID:21068016

Ekendahl, Daniela; Judas, Libor

2011-04-01

16

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

PubMed

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

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

2012-04-01

17

Effect of the Temperature and Relative Humidity in Dosemeters Used for Personnel Monitoring.  

National Technical Information Service (NTIS)

The systematics of the combined effect of temperature and humidity on photographic dosimeters of the type Agfa-Gevaert, Kodak type II, III and the thermoluminescent dosimeters LiF:Mg,Ti (TLD-100, Harshaw), D-CaSO sub 4 :Dy-0,4 (Teledyne), e CaSO sub 4 :Dy...

J. Antonio Filho

1982-01-01

18

New concept of IEC standards for radiation protection dosemeters.  

PubMed

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

Ambrosi, P; Behrens, R

2008-01-01

19

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

SciTech Connect

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

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

2008-01-01

20

High-energy response of passive dosemeters in use at LANL.  

PubMed

The high-energy neutron response of three passive dosemeters in use at the Los Alamos National Laboratory (LANL) has been investigated using metrology-grade fields. The dosemeters include the LANL Model 8823 TLD badge and the LANL PN3 track etch device. Both are dosemeters of record at LANL. The third device was the Personal Neutron Dosemeter (PND), a superheated emulsion device, manufactured by Bubble Technology Industries, Inc. (BTI). The response of the three dosemeters at neutron energies exceeding 10 MeV was assessed with monoenergetic neutrons at the Physikalisch-Technische Bundesanstalt facility (14.8 and 19 MeV). For the sake of completeness, data collected at lower energies are also included in this study. High-energy quasi-monoenergetic beams produced by the cyclotron facilities at the Université Catholique de Louvain (UCL) and the The Svedberg Laboratory (TSL) were also utilised as part of this study. These measurements were made to better understand and help interpret dosemeter readings obtained by workers at high-energy accelerators, such as the 800 MeV spallation neutron source facility located at the Los Alamos Neutron Science Center (LANSCE). PMID:17522036

Olsher, Richard H; McLean, Thomas D; Mallett, Michael W; Romero, Leonard L; Devine, Robert T; Hoffman, Jeffrey M

2007-01-01

21

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

22

Characterisation of PRESAGE: A new 3-D radiochromic solid polymer dosemeter for ionising radiation.  

PubMed

For the past 50 years there has been interest in developing 3-D dosemeters for ionising radiation. Particular emphasis has been put on those dosemeters that change their optical properties in proportion to the absorbed dose. Many of the dosemeters that have been evaluated have had limitations such as lack of transparency, diffusion of the image of the dose distribution or poor stability of baseline optical density. Many of these performance limitations have been overcome by the development of PRESAGE, an optically clear polyurethane-based radiochromic 3-D dosemeter. The solid PRESAGE dosemeter is formulated with a free radical initiator and a leuco dye and it does not require a container to maintain its shape. The polyurethane matrix is tissue equivalent and prevents the diffusion of the dose distribution image. There is a linear dose-response, which is independent of both photon energy and dose rate. Simple precautions such as preventing long-term exposure to additional ionising radiation including ultraviolet and controlling storage temperatures prevent the bleaching of the radiochromic response field within the irradiated dosemeter. PMID:16782984

Adamovics, J; Maryanski, M J

2006-01-01

23

Recent results of irradiations of DIS-1 dosemeters with an XR200 X-ray flash unit.  

PubMed

Earlier measurements have revealed that active electronic dosemeters have deficiencies in pulsed fields of ionising radiation due to the counting technique used. The DIS-1 dosemeter uses a promising technology, which should be basically suitable for measurements in pulsed fields. In this paper, first measurements with the DIS-1 dosemeter at an X-ray flash generator XR200 with pulse durations of ?115 ns and doses per pulse of a few microsievert are shown. PMID:23075930

Zutz, H; Hupe, O

2013-05-01

24

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

PubMed Central

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

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

2012-01-01

25

Calculated angular responses of an RPL dosemeter to photon and beta radiation.  

PubMed

The calculated dose equivalent response as a function of the angle has been examined for the radiophotoluminescent (RPL) glass dosemeter that was exposed to narrow series X-ray, N-60, N-80, N-100, N-150, N-200, N-250, N-300, photon sources ((60)Co and (137)Cs) and beta-ray emitter ((90)Sr/(90)Y) while mounted on an ISO water slab phantom. The angular dose equivalent responses H(p)(10) and H(p)(0.07) were calculated using the Monte Carlo MCNPX code. The RPL dosemeter and the phantom were rotated in the horizontal and vertical planes from a variety of angles of interest. The results were compared with the experimental data. Good agreement was found between the measured and calculated values of the relative dose equivalent angular responses of the RPL dosemeter. PMID:22361351

Hocine, Nora

2012-08-01

26

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

27

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

PubMed

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

Czarwinski, R; Kaulard, J; Pfeffer, W

2007-01-01

28

The applicability of radiophotoluminescence dosemeter (RPLD) for measuring medical radiation (MR) doses.  

PubMed

The applicability of radiophotoluminescence dosimetry was determined by assessing various radiophotoluminescence dosemeter (RPLD) properties for measuring medical radiation doses from radiation sources of a continuous spectrum. The RPLD was found to be accurate for measuring doses in diagnostics (50-125 keV) and radiation therapy (6, 10 and 18 MV photons, 6 and 15 MeV electrons). The RPLD shows excellent dose linearity (R(2) > 0.99), reproducibility and batch uniformity, and minimal fading and accurate accumulated dose measurement. The dosemeter material is independent of photon energy in the diagnostic range; however, the dosemeter requires additional calibration in the mammography energy range and also for accurate dose measurement with photon or electron energies in radiation therapy. RPLD measurements with a tin filter show considerable angular dependence at angles exceeding 50° between the photon beam and the normal to the long axis of the dosemeter. The RPLD measurement accuracy at high doses can be improved with optimised pre-heating schemes. PMID:22232778

Manninen, A-L; Koivula, A; Nieminen, M T

2012-08-01

29

A catalogue of dosemeters and dosimetric services within Europe--an update.  

PubMed

The catalogue of dosemeters and dosimetric services within the European Union (EU) Member States and Switzerland that was issued by EURADOS in the year 2000 has been updated and extended with information on dosimetric services in the new EU Member States and Bulgaria, Croatia, Romania, Serbia and Montenegro, and Ukraine. The total number of dosimetric services in these European countries is now estimated to be about 200. The present catalogue is based on information collected from 90 European dosimetric services, among which 34 questionnaires from 32 services were obtained over the years 2001-2004 for the first time. This article assesses and updates the present use of personal dosemeters and the extent to which occupationally exposed persons in Europe are monitored with dosemeters able to measure the operational quantity-personal dose equivalent, H(P)(d). The perspective of joining EU by the new countries accelerated the implementation of the EU Basic Safety Standard Directive to their national regulations. As a result, all newly investigated services reported their ability to measure H(P)(d). The catalogue provides information on the dosemeters, dose calculation and background subtraction algorithms, calibration methods, energy and angular response, and performance. PMID:15574986

Lopez Ponte, M A; Castellani, C M; Currivan, L; VanDijk, J W E; Falk, R; Olko, P; Wernli, C

2004-01-01

30

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

PubMed

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

Becková, Vera; Malátová, Irena

2008-01-01

31

Evaluating the uncertainty in measurement of occupational exposure with personal dosemeters.  

PubMed

In the 1990 Recommendations of the ICRP it is stated that an uncertainty in a dose measured with a personal dosemeter under workplace conditions of a factor 1.5 in either direction 'will not be unusual'. In many documents similar to the EU Technical recommendations, the IAEA Safety Guides and papers in scientific journals, this statement is understood to be a basis for developing type-test criteria and criteria for the approval of dosimetric systems. The methods for evaluating the standard uncertainty as proposed in the above mentioned documents and in national and international standards use an approach that is based on the Law of Propagation of Uncertainties (LPU). This approach needs a number of assumptions, the validity of which cannot easily be verified for personal dosemeters. The current paper presents a numerical method based on Monte Carlo simulation for the calculation phase of the evaluation of uncertainties. The results of applying the method on the type-test data of the NRG TL-dosemeter indicate that the combined standard uncertainty estimated using the LPU approach might well not be realistic. The numerical method is simple and can be precisely formulated, making it suitable for being part of approval or accreditation procedures. PMID:17261535

van Dijk, J W E

2007-01-01

32

DOSIMAP: a high-resolution 2-D tissue equivalent dosemeter for linac QA and IMRT verification.  

PubMed

New generation of radiation therapy accelerators requires highly accurate dose measurements with high spatial resolution patterns. IMRT is especially demanding since the positioning accuracy of all the multi-leafs should be verified for each applied field and at any incidence. A new 2-D tissue equivalent dosemeter is presented with high spatial resolution that can fulfil these tasks. A plastic scintillator sheet is sandwiched between two polystyrene cubes, and the emitted light is observed by a high-resolution camera. A patented procedure allows efficient discrimination of the scintillation proportional to the dose from the parasitic Cerenkov radiation. This extraction made on the cumulated images taken during an irradiation field at a rate of 10 images s(-1) provides high-resolution mapping of the dose rate and cumulated dose in quasi real time. The dosemeter is tissue equivalent (ICRU-44) and works both for electrons and photons without complex parameter adjustment, since phantom and detector materials are identical. The calibration is simple and independent of the irradiation conditions (energy, fluence, quality and so on). The principle of the dosemeter and its calibration procedure are discussed in this paper. The results and, in particular, the dose depth profiles are compared with standard ionisation chamber measurements in polystyrene for both photons and electrons. Finally, the detector specifications are summarised and one example of complex IMRT field is discussed. PMID:18757897

Collomb-Patton, V; Boher, P; Leroux, T; Fontbonne, J-M; Batalla, A; Vela, A

2008-01-01

33

The 12B counter: an active dosemeter for high-energy neutrons.  

PubMed

High-energy accelerators can produce strong time-structured radiation fields. Such dose shots are generated at linear machines with low duty cycles as well as at circular machines when complete fills are instantaneously lost. The main dose component behind thick shielding is due to high-energy neutrons occurring at that time structure. Dosemeters based on Geiger-Mueller tubes or proportional counters fail here completely. The 12B counter, a novel dosemeter made of a plastic scintillator using carbon activation for event-like exposure, has been introduced. High-energy neutrons activate the carbon nuclei by three inelastic reactions. The decay patterns with half-lives between 20 ms and 20 min can be exploited depending on the time structure of the radiation field. The response of the 12B counter was measured along with some other dosemeters, both active and passive, in the radiation field behind the lateral concrete shielding of a 7.5 GeV proton transfer line. PMID:16604616

Leuschner, A

2005-01-01

34

Reproducibility of TL measurements in a mixed field of thermal neutrons and photons.  

PubMed

The reproducibility of measurements performed with GR-100 (LiF:Mg,Ti) from the Solid Dosimetric Detector and Method Laboratory (DML) China, GR-107 (7LiF:Mg,Ti, DML), TLD-700H (7LiF:Mg.Cu,P, Harshaw) and Al2O3:Mg,Y (Hungary) in photon and mixed photon-neutron fields was investigated. Mixed-field irradiations were performed in a thermal neutron field generated at a nuclear reactor. GR-100 sensitivity decreased after mixed-field irradiations, while no significant change was found for the other materials. Using GR-100 for the dosimetry of mixed and high-intensity fields requires careful procedures. PMID:12382796

Fernandes, A C; Gonçalves, I C; Ferro Carvalho, A; Santos, J; Cardoso, J; Santos, L; Osvay, M

2002-01-01

35

Evaluations of absorbed dose ratio factor of Al2O3 dosemeter in radiotherapy photon beams using cavity theory.  

PubMed

The aim of the work was to evaluate the absorbed dose ratio factor f(md) of an Al(2)O(3) dosemeter to water in photon radiotherapy beams using cavity theory. Burlin theory was used for calculating of this ratio. The effective mass attenuation coefficient ? was obtained by comparing Monte Carlo simulations in monoenergetic photon beams. The evaluations of the absorbed dose ratio factor f(md) were studied for Al(2)O(3) dosemeters of different sizes, which were placed at various depths of the water phantom in different radiation field sizes of Mohan's 6, 10 and 15-MV X-rays. Beyond the build-up region, the variation of f(md) increases by 0.25 % as the depth increases from 4 to 10 cm. The maximum variation due to different dosemeter sizes is 8.3 %. The difference in the f(md) due to different radiation field sizes is 1.5 %. The effect of the dosemeter size cannot be neglected. The difference in the f(md) due to the radiation field sizes of different beams would increase as the dosemeter size increases. PMID:22562942

Zhu, Jinhan; Chen, Shaowen; Chen, Lixin; Liu, Xiaowei

2012-12-01

36

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

PubMed

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

Boschung, M; Fiechtner, A; Wernli, C

2007-01-01

37

Dose evaluation in criticality accidents using response of Panasonic TL personal dosemeters (UD-809/UD-802).  

PubMed

This study gives the results of dosimetry measurements carried out in the Silčne reactor at Valduc (France) with neutron and photon personal thermoluminescence dosemeters (TLDs) in mixed neutron and gamma radiation fields, in the frame of the international accident dosimetry intercomparison programme in 2002. The intercomparison consisted of a series of three irradiation scenarios. The scenarios took place at the Valduc site (France) by using the Silčne experimental reactor. For neutron and photon dosimetry, Panasonic model UD-809 and UD-802 personal TLDs were used together. PMID:22389154

Zeyrek, C T; Gündüz, H

2012-09-01

38

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

PubMed

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

Souto, E B; Campos, L L

2011-03-01

39

Portable transfer digital dosemeter for beam output measurements with X and gamma rays, electrons and neutrons.  

PubMed

This instrument was developed in response to a requirement for an accurate, stable and portable transfer dosemeter for calibration, at therapy dose levels, of equipment used for generating X and gamma rays, electrons and neutrons. The detector is a 0.5 cm3 ionization chamber capable of fitting various wall materials reproducibly at the end of the chamber stem. The measuring system uniquely combines the features of a MOSFET electrometer and an automatic Townsend balance. When used for X, gamma and neutron radiations, the instrument measures the tissue kerma in free air on two ranges: 0.001 - 1.999 Gy (0.1 - 199.9 rad) and 0.01 - 19.99 Gy (1 - 1999 rad) or their exposure equivalents, with autoranging feature when the first range is exceeded. The polarizing voltage (180 V) can be reversed for electron and neutron dosimetry. The dosemeter has a measuring accuracy of +/- 0.2% FS +/- 1 digit and operates on four 1.5 V torchlight cells or on AC mains (200-250 V, 50 - 60 Hz). It utilizes solid state devices, CMOS integrated circuits and displays, and is not affected by RF fields. The instrument is enclosed in a brief-case for portability and is easy to operate and maintain in a hospital. PMID:7225720

Sankaran, A; Gokarn, R S; Gangadharan, P

1981-04-01

40

ENEA extremity dosemeter based on LiF(Mg,Cu,P) to evaluate Hp(3,alpha).  

PubMed

Recent epidemiological studies suggest a rather low-dose threshold (<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 optimised and current dose limits for the eye lens may be reduced in the future. ICRP Publication 103 on H(p)(d), in §(136), reads that '… a depth d = 3 mm has been proposed for the rare case of monitoring the dose to the lens of the eye. In practice, however, H(p)(3) has rarely been monitored and H(p)(0.07) can be used for the same monitoring purpose… '. As recommended on the EU 'Technical recommendations for monitoring individuals occupationally exposed to external radiation', a test on the ENEA TL extremity dosemeter is herein reported. The results within the actual EU founded Optimization of RAdiation protection for MEDical staff (ORAMED) Project, whose WP2 is aimed at the quantity H(p)(3) and eye lens dosimetry in practice, are taken into account. The paper summarises the main aspects of the study carried out at ENEA-Radiation Protection Institute (Bologna, Italy) to provide practical solutions (in the use and the design) to evaluate the response of the ENEA TL extremity dosemeter in terms of H(p)(3). PMID:21224262

Mariotti, F; Fantuzzi, E; Morelli, B; Gualdrini, G; Botta, M C; Uleri, G; Bordy, J M; Denoziere, M

2011-03-01

41

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

42

Automation of radiation dosimetry using PTW dosemeter and LabVIEW™  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

43

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

PubMed

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

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

2013-08-01

44

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

45

The use of Lithium Flouride Thermoluminescent Dosemeters to measure the Dose Distribution of a 15 MeV Electron Beam  

Microsoft Academic Search

A comparison was made of the central axis depth-dose curves obtained for 15 MeV electrons using an ion chamber and LiF dosemeters. The two uncorrected curves were very similar and gave the same depth-dose curves within experimental limits. Corrections that must be made to the LiF curve for energy and dose dependence and to the ion chamber readings for the

Peter R Almond; Ann Wright; J. F. Lontz II

1967-01-01

46

Al 2O 3:C as a sensitive OSL dosemeter for rapid assessment of environmental photon dose rates  

Microsoft Academic Search

The use of Al2O3:C single crystals as optically stimulated luminescnce (OSL) dosemeters for rapid assessment of the environmental photon dose rate is proposed. It is shown that Al2O3:C possesses higher OSL sensitivity than TL sensitivity. In TL measurements thermal quenching is a major problem that crucially depends on the heating rate used and, therefore, the all-optical nature of the OSL

L. Břtter-Jensen; N. Agersnap Larsen; B. G. Markey; S. W. S. McKeever

1997-01-01

47

Comparison of neutron dose quantities and instrument and dosemeter readings at representative locations in an MOX fuel fabrication plant  

NASA Astrophysics Data System (ADS)

The relationships between operational and protection quantities, and values of personal dosemeter and instrument readings have been determined for a recently designed MOX fuel fabrication plant. The relationships between the quantities, and the readings of personal dosemeters are sensitive to both the energy and direction distribution of neutron fluence. The energy distributions were calculated using the Monte Carlo code MCBEND. The direction distribution was addressed by calculating independently, spectral components for which the direction distribution could be reasonably assumed. At representative locations, and for assumed worker orientations, the radiation field is analysed as having, in general, three components—a direct, unidirectional component from the nearest identified discrete source, which is considered incident A-P, several unidirectional components from other such sources which are treated as a rotational component and a scattered isotropic component. The calculated spectra were folded with conversion coefficients for personal dose equivalent, Hp(10) slab (A-P, ROT and ISO), effective dose, E, (A-P, ROT and ISO), ambient dose equivalent, H*(10), personal dosemeter (AP, ROT and ISO) and survey instrument response characteristics.

Bartlett, D. T.; Hager, L. G.; Tanner, R. J.; Haley, R. M.; Cooper, A. J.

2002-01-01

48

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

49

Selection of the most appropriate two-dosemeter algorithm for estimating effective dose equivalent during maintenance periods in Korean nuclear power plants.  

PubMed

The application of a two-dosemeter system with its algorithm, as well as a test of its use in an inhomogeneous high-radiation field, is described in this study. The goal was to improve the method for estimating the effective dose equivalent during maintenance periods at Korean Nuclear Power Plants (NPPs). The use of this method in Korean and international NPPs, including those NPPs in the USA and Canada, was also investigated. The algorithms used by the the American National Standards Institute, Lakshmanan, the National Council on Radiation Protection and Measurements (NCRP), the Electric Power Research Institute and Kim were extensively analysed as two-dosemeter algorithms. Their possible application to NPPs was evaluated using data for each algorithm from two-dosemeter results that were obtained from an inhomogeneous high-radiation field during maintenance periods at Korean NPPs. The NCRP algorithm (55:50) was selected as an optimal two-dosemeter algorithm for Korean NPPs by taking into account the field test results and the convenience of wearing two dosemeters. PMID:20203124

Kim, Hee Geun; Kong, Tae Young

2010-07-01

50

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

PubMed

A significant proportion of cancer patients is treated using MeV electron radiation. One of the measurement methods which is likely to furnish reliable dose values also under non-reference conditions is the dosimetry using alanine and read-out via electron spin resonance (ESR). The system has already proven to be suitable for QA purposes for modern radiotherapy involving megavoltage x-rays. In order to render the secondary standard measurement system of the Physikalisch-Technische Bundesanstalt based on alanine/ESR useable for dosimetry in radiotherapy, the dose-to-water (D(W)) response of the dosemeter needs to be known for relevant radiation qualities. For MeV electrons, the D(W) response was determined using the Fricke primary standard of the Swiss Federal Office of Metrology. Since there were no citable detailed publications on the Swiss primary standard available, this measurement system is described in some detail. The experimental results for the D(W) response are compared to results of Monte Carlo simulations which model in detail the beams furnished by the electron accelerator as well as the geometry of the detectors. The agreement between experiment and simulation is very good, as well as the agreement with results published by the National Research Council of Canada which are based on a different primary standard. No significant dependence of the D(W) response was found in the range between 6 and 20?MeV. It is therefore suggested to use a unique correction factor k(E) for alanine for all MeV qualities of k(E) = 1.012 ± 0.010. PMID:22349609

Vörös, Sándor; Anton, Mathias; Boillat, Bénédicte

2012-03-01

51

Characterisation of energy response of Al2O3:C optically stimulated luminescent dosemeters (OSLDs) using cavity theory  

PubMed Central

Aluminium oxide (Al2O3:C) is a common material used in optically stimulated luminescent dosemeters (OSLDs). OSLDs have a known energy dependence, which can impact on the accuracy of dose measurements, especially for lower photon energies, where the dosemeter can overrespond by a factor of 3–4. The purpose of this work was to characterise the response of Al2O3:C using cavity theory and to evaluate the applicability of this approach for polyenergetic photon beams. The cavity theory energy response showed good agreement (within 2 %) with the corresponding measured values. A comparison with measured values reported in the literature for low-energy polyenergetic spectra showed more varied agreement (within 6 % on average). The discrepancy between these results is attributed to differences in the raw photon energy spectra used to calculate the energy response. Analysis of the impact of the photon energy spectra versus the mean photon energy showed improved accuracy if the energy response was determined using the entire photon spectrum rather than the mean photon energy. If not accounted for, the overresponse due to photon energy could introduce substantial inaccuracy in dose measurement using OSLDs, and the results of this study indicate that cavity theory may be used to determine the response with reasonable accuracy.

Scarboro, S. B.; Kry, S. F.

2013-01-01

52

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

PubMed

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

Daniels, R D; Schubauer-Berigan, M K

2005-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

54

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

PubMed

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

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

2006-01-01

55

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

PubMed

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

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

2006-01-01

56

Extremity and whole-body dosemeters for beta and beta gamma fields based on LiF:Mg,Cu,P thin detectors.  

PubMed

This study aims at proposing two TL dosemeters: one for the whole body and another for the extremities, for beta and gamma fields. Selected sensible material consists of 5 mg x cm(-2) LiF:Mg,Cu,P film (GR-200F) manufactured in China. Calibration was carried out according to ISO 4037-3, in terms of Hp(0.07), and dosimetric performance was analysed on the basis of IEC-1066 and ISO-12794 Standards. Experiments showed a satisfactory sensitivity of the proposed dosemeters for detecting beta radiation at protection levels and a very good energy response; thus, highly recommending their use for weakly penetrating radiation measurements. However, the homogeneity and the reproducibility of GR-200F are not found to be as reliable as in standard materials. PMID:12382748

Pérez, S; Ginjaume, M; Ortega, X; Duch, M A; Roig, M

2002-01-01

57

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

58

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

PubMed

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

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

2003-01-01

59

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

PubMed

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

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

2013-12-01

60

Analysis of neutron and photon response of a TLD-ALBEDO personal dosemeter on an ISO slab phantom using TRIPOLI-4.3 Monte Carlo code.  

PubMed

TRIPOLI-4.3 Monte Carlo transport code has been used to evaluate the QUADOS (Quality Assurance of Computational Tools for Dosimetry) problem P4, neutron and photon response of an albedo-type thermoluminescence personal dosemeter (TLD) located on an ISO slab phantom. Two enriched 6LiF and two 7LiF TLD chips were used and they were protected, in front or behind, with a boron-loaded dosemeter-holder. Neutron response of the four chips was determined by counting 6Li(n,t)4He events using ENDF/B-VI.4 library and photon response by estimating absorbed dose (MeV g(-1)). Ten neutron energies from thermal to 20 MeV and six photon energies from 33 keV to 1.25 MeV were used to study the energy dependence. The fraction of the neutron and photon response owing to phantom backscatter has also been investigated. Detailed TRIPOLI-4.3 solutions are presented and compared with MCNP-4C calculations. PMID:16381740

Lee, Y K

2005-01-01

61

Experimental Calibration and Determination of the Relative Response for Lif: Mg, Ti(TLD-100) Dosemeters at sup 60 Co gamma and 60 kVp X-Ray Energies.  

National Technical Information Service (NTIS)

The thermoluminescence efficiency of LiF: Mg, Ti (TLD-100) dosemeters has been determined for photon beams from sup 60 Co gamma rays and 60 kVp X-rays. It has been proven that light yield varies as a function of the photon energy. An experiment was perfor...

M. L. Marco L. Gonzalez V. Delgado E. Vano P. Moran

1985-01-01

62

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

PubMed

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

Miller, Steven D; Murphy, Mark K

2007-01-01

63

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

PubMed

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

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

2011-03-01

64

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

PubMed

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 measurement was normalized to the value produced by 6 MV X-rays. LiF:Mg:Cu:P was found to under-respond to a majority of these radiations whereas LiF:Mg:Ti over-responded to a majority. Their smallest relative measured response was produced by the lowest energy beam, and the maximum measured relative response of 1.15+/-0.07 and 1.21+/-0.07 for LiF:Mg:Cu:P and LiF:Mg:Ti, respectively, occurred at 33 keV. Energy response coefficients were derived from these measurements to estimate the error introduced by using either type of TLD to measure the dose from an X-ray spectrum different to that used for its absolute response calibration. It was calculated that if the response of either type of TLD was calibrated at 100 kVp, then an error of no more than +/-2% would be introduced into measurements of tube output at potentials of 50-130 kVp. LiF:Mg:Cu:P was found to introduce a larger error (up to 30%) into the measurement of body exit dose than LiF:Mg:Ti at tube potentials of 40-150 kVp, if its absolute response was calibrated using the corresponding body entrance beam. The method should allow this type of error to be estimated in other dosimetry applications for either type of TLD. PMID:15900061

Edwards, C R; Mountford, P J; Green, S; Palethorpe, J E; Moloney, A J

2005-06-01

65

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

SciTech Connect

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

Sonder, E.; Ahmed, A.B.

1993-05-01

66

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

National Technical Information Service (NTIS)

A large number of dosimeters that have produced abnormal data during field assignment have been stored, reirradiated, and studied. Results are summarized and comparisons are made with normal dosimeters. Summarized here are anomalous glow curve shapes, dis...

E. Sonder A. B. Ahmed

1993-01-01

67

Telephone chip-cards as individual dosemeters  

Microsoft Academic Search

It has been observed that a certain type of telephone chip-card can be used as radiation detectors for individuals exposed to external gamma doses. The radiation dose responses of more than 200 chip-cards, produced by various companies since 1990, were investigated using infrared stimulated luminescence (IRSL). The radiation dose responses of some of the chip-cards were found to be compatible

H. Y. Göksu

2003-01-01

68

Intercomparison Study of Thermoluminescent Dosemeters for Environmental Measurements.  

National Technical Information Service (NTIS)

The importance of the relatively large contribution to human exposure levels made by natural radiation has long been recognized. The development of thermoluminescence and etched-track dose measurement techniques have led to a renewed interest in quantitat...

A. F. McKinlay

1985-01-01

69

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

70

Phototransferred Thermoluminescence of KCL:Eu2+ Dosemeters  

NASA Astrophysics Data System (ADS)

The phototransferred thermoluminescence (PTTL) of KCl:Eu2+ crystals was studied after exposure to X -rays or ? radiation. The main thermoluminescence (TL) peaks were found around 370, 390 and 470 K. The 470 K highest intensity peak is considered to be the dosimetric peak due to its low fading and linear dose behavior. The main dosimetric peak is sharply decreased after illumination with UV light of a previously irradiated specimen. The PTTL is wavelength dependent and has been shown to peak in the 220 - 230 nm region and 650 nm in previously non irradiated and irradiated samples, respectively. The PTTL spectral response is always a broad band around 390 - 490 nm peaked at 425 nm, which is related to the well-known Eu2+ emission.

Barboza-Flores, M.; Meléndrez, R.; Chernov, V.; Bernal, R.; Piters, T. M.; Pérez-Salas, R.; Aceves, R.; Pedroza-Montero, M.; Castańeda, B.

2001-04-01

71

Individual gamma Dosemeter MD 20: Physical Tests and Evaluation Tests.  

National Technical Information Service (NTIS)

Tests on the digital individual dose ratemeter type DM 20 for gamma radiation measurement are presented. The aim of this testing is an evaluation of main physical characteristics under irradiation. Results are given in tables and graphs. Relative sensitiv...

R. Laureana

1981-01-01

72

OSL response to proton irradiation in some natural dosemeters: Implications for martian sediment dating  

Microsoft Academic Search

The knowledge of environmental dose rate on Mars is crucial for in situ Optically Stimulated Luminescence (OSL) dating of martian sediments. Protons are the dominant source of dose rate on Mars. The efficiency of OSL production after proton irradiation depends on the proton's Linear Energy Transfer (LET). Since the absorbed dose estimates are usually derived using a low LET reference

M. Jain; C. E. Andersen; W. Hajdas; J. M. Edmund; L. Břtter-Jensen

2007-01-01

73

Anomalous results with the widely used NRPB/SSI-type passive radon dosemeter.  

PubMed

In an industrial hall, with large variations of radon concentration within minutes, simultaneous measurements were done with two types of passive radon detectors and an active radon measuring device. The widely used passive radon detector of the National Radiological Protection Board (NRPB) [Health Protection Agency (former NRPB) (HPA)]/Statens strĺlskyddsinstitut (Swedish Radiation Protection Institute) (SSI) type produced anomalous results, seemingly uncorrelated to the radon concentration which was in the order of hundreds of becquerels per metre, usually underestimating but occasionally overestimating. We tried to reproduce similar exposure characteristics in our laboratory, but failed to reproduce the anomalous readings. We suspected, but could not prove, that the anomalous results were due to the combination of high radon concentration gradients, with pressure-driven air exchange between the inside of the detector holder and the outside atmosphere. Moreover, this theory was at least partly contradicted when we drilled holes in the detector holder. Although of interest, this effect is not likely to have substantially influenced any radon surveys, given the unusual nature of the exposure that caused the effect. PMID:20858675

Paridaens, J

2010-12-01

74

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

NASA Astrophysics Data System (ADS)

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.; Rambousky, R.; Buchholz, F. W.

2008-08-01

75

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

76

Properties of TL Dosemeters after Irradiation with High Heavy Ion Doses.  

National Technical Information Service (NTIS)

The TL phosphors LiF:Mg,Ti and CaF sub 2 :Mn (Dohnalum products in powder and disk form) have been irradiated with high doses of 630 MeV protons, 73 MeV sup 12 C and 75 MeV sup 18 O ions. The dose-response characteristics in the dose ranges of 10 exp -1 t...

K. Huebner

1981-01-01

77

Properties of TL Dosemeters after Irradiation with Heavy Ions at High Doses.  

National Technical Information Service (NTIS)

The thermoluminescent phosphors LiF:Mg,Ti and CaF sub 2 :Mn were irradiated at different JINR accelerators with 630 MeV protons and with exp 12 C exp 6+ ions (73 MeV) and exp 18 O exp 8+ ions (75 MeV). For LiF luminophors (used in the thermoluminescent do...

K. Huebner

1981-01-01

78

Development of a framework of quality assurance practices for a radon passive dosemeter service.  

PubMed

Etched track detectors are widely used for the detection of radon and its decay products. The reliability of radon measurement performed with such devices requires that laboratories producing analytical data are able to provide results of the required quality. The need for uniform results from laboratories at an international level therefore requires the implementation of a quality assurance programme, the harmonization of criteria, sampling procedures, calculations and the reporting of results, agreed on the basis of fundamental principles and international standards. The quality assurance programme described here is the first step on the way to ISO/IEC 17025 certification for the RI-RN (ISPESL) laboratory. PMID:20530856

D'Alessandro, M; Leonardi, F; Tonnarini, S; Trevisi, R; Veschetti, M

2010-06-01

79

Assessment of medical occupational radiation doses in Costa Rica.  

PubMed

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

Mora, P; Acuńa, M

2011-09-01

80

Calibracao de um dosimetro de albedo no ciclotron CV-28. (Calibration of an albedo dosemeter at CV-28 cyclotron).  

National Technical Information Service (NTIS)

This work deals with the analysis and application of neutron measurement techniques in order to obtain information on the neutron spectrum and neutron dose equivalent at several representative working places of the cyclotron laboratory of the Instituto de...

P. W. Fajardo C. L. P. Mauricio

1991-01-01

81

Response Behavior of the Most Employed Individual Monitoring Thermoluminescent Dosemeters under Different Conditions of Temperature and Relative Humidity.  

National Technical Information Service (NTIS)

The influence of the temperature and the humidity on the stability of the response of LiF:Mg,Ti(TLD-100), LiF:Mg,Ti(TLD-700), CaSO4:Dy++Teflon(D-CaSO4:Dy-0,4), CaF2:Dy(TLD-200) and Li2B4O7:Mn,Si thermoluminescent detectors was investigated. The detectors ...

L. A. R. Rosa B. Burgkhardt

1988-01-01

82

Evaluation of dose equivalent by the electronic personal dosemeter for neutron 'Saphydose-N' at different workplaces of nuclear facilities.  

PubMed

This paper presents the results of measurements made with the electronic personal neutron Saphydose-N during the four campaigns of the European contract EVIDOS (EValuation of Individual DOSimetry in mixed neutron and photon radiation fields). These measurements were performed at Institute for Radiological Protection and Nuclear Safety (IRSN) in France (C0), at the Krümmel Nuclear Power Plant in Germany (C1), at the VENUS Research Reactor and the Belgonucléaire fuel processing plant in Belgium (C2) and at the Ringhals Nuclear Power Plant in Sweden (C3). The results for Saphydose-N are compared with reference values for dose equivalent. PMID:17110389

Chau, Q; Lahaye, T

2007-01-01

83

Investigation of some commercial TLD chips/discs as UV dosimeters  

NASA Astrophysics Data System (ADS)

Using a deuterium UV source, we have investigated the response of a number of commercially available thermoluminescence (TL) dosimeters (TLDs) to UV radiation (UVR), including LiF : Mg, Cu, P (TLD-100 H), CaF 2 : Dy (TLD-200), CaF 2 : Mn (TLD-400), Al 2O 3 (TLD-500), 7LiF : Mg, Cu, P (TLD-700 H) and CaSO 4 : Dy (TLD-900). The intrinsic method was used to detect UVR, while trap depth and frequency factors were estimated using the initial rise method. We have studied TL intensity as a function of exposure time, observing high sensitivity of TLD-500 to UVR. Conversely, TLD-400 displays weak sensitivity to these same radiations. Although TLD-900 and TLD-200 are both less sensitive to UVR than TLD-500, they each provide a linear response to UVR. The possible use of these phosphors as UV dosimeters has been further appraised, examining thermal fading effects and fading due to light exposure.

Noh, Abdullah M.; Amin, Yusoff M.; Mahat, Rosli H.; Bradley, D. A.

2001-06-01

84

Thermoluminescence and photoluminescence characteristics of nanocrystalline LiNaSO4 : Eu phosphor  

NASA Astrophysics Data System (ADS)

Europium doped LiNaSO4 in its nanocrystalline form has been prepared and its thermoluminescence (TL) properties are studied. The TL glow curve of the phosphor has been found to have a simple structure with a single peak at 432 K. Though the highly sensitive, commercially available TL phosphor LiF : Mg, Cu, P (TLD-700H) is about 1.5 times more sensitive than the nanocrystalline material, the sensitivity of the concerned nanomaterial is much higher (~10 times) than the other standard phosphor TLD-100 (LiF : Mg, Ti). Compared to the conventional LiNaSO4 : Eu phosphor (prepared through a melting procedure and having particle size of 125 µm), the nano-sized phosphor has a lesser TL sensitivity. However, this reduction in TL sensitivity on decreasing the particle size from micrometres to nanometres gives a better understanding of the TL phenomenon. The order of TL kinetics for the concerned nanomaterial is also found to be different from that of the conventional material. Photoluminescence studies that have been performed on these materials throw light on the reasons for such a change in the order of kinetics. Further, fading and reusability of the concerned nanomaterial has also been studied and it has been found that the phosphor is quite suitable for radiation dosimetry.

Pandey, A.; Sahare, P. D.; Bakare, J. S.; Lochab, S. P.; Singh, F.; Kanjilal, D.

2003-10-01

85

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

Microsoft Academic Search

The dose ranges typical for radiation oncology and nuclear accident dosimetry are on the order of 2?70 Gy and 0.1?5 Gy, respectively. In terms of solid-state passive dosimetry; thermoluminescent (TL) materials historically have been used extensively for these two applications, with silver-halide, leuco-dye, and BaFBr:Eu-based films being used on a more limited basis than TL for radiation oncology. This present

Steven D. Miller; Mark K. Murphy

2006-01-01

86

Thoron and radon diffusion through different types of filter  

Microsoft Academic Search

Can-type dosemeters containing solid state nuclear track detectors have been involved in many studies of radon concentration in the environment. A filter usually blocks the entrance face for radon into such a dosemeter. One of the main purposes of such a filter is to stop thoron gas from entering the dosemeter — which is usually calibrated only for radon (222Rn,

R. Shweikani; B. Al-Bataina; S. A. Durrani

1997-01-01

87

Progettazione di un dosimetro personale a termoluminescenza con rivelatori di LiF (Mg, Cu, P) per radiazione fotonica. (Personnel thermoluminescent dosemeter using LiF (Mg, Cu, P) detectors).  

National Technical Information Service (NTIS)

Since about thirty years a the Bologna ENEA (Italian Agency for New Technologies, Energy and the Environment) has been carrying out a personal dosimetry service for ionizing radiations. To this end a significant part of the applied research in the dosimet...

E. Fantuzzi F. Monteventi U. De Maio R. Poli G. C. Uleri

1994-01-01

88

Redox reactions in Cu-activated nanocrystalline LiF TLD phosphor  

NASA Astrophysics Data System (ADS)

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

Singh, Manveer; Sahare, P. D.

2012-10-01

89

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

Microsoft Academic Search

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

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

2010-01-01

90

Effect of Plastic Deformation on the Thermoluminescence of gamma-Irradiated KCl Crystals  

Microsoft Academic Search

The effect of plastic deformation on the thermoluminescence of nominally pure Harshaw KCl samples gamma irradiated at room temperature has been studied up to 450 °C. In samples plastically strained prior to irradiation a new glow peak appears. It has been found that this glow peak does not follow either first- or second-order kinetics. It is shown that the phosphorescence

V. Ausín; J. L. Alvarez Rivas

1972-01-01

91

Evaluation of a linear position sensitive neutron detector for powder spectroscopy  

Microsoft Academic Search

A one meter long position sensitive detector was acquired from Harshaw Corp. for a small angle neutron camera operated by the University of Rhode Island at the 2 MW reactor of the Rhode Island Nuclear Science Center. In the course of testing the detector system, to determine linearity, resolution, stability and efficiency, it was employed in a powder spectrometer. Once

I.-Ping Chang; A. C. Nunes

1982-01-01

92

Alanine blends for ESR measurements of thermal neutron fluence in a mixed radiation field.  

PubMed

In this paper, the results of a study on the electron spin resonance (ESR) dosimetry to measure thermal neutron fluence in a mixed radiation field (neutron and photons) are presented. The ESR responses of alanine dosemeters with different additives are compared. In particular, the (10)B-acid boric and the Gd-oxide were chosen to enhance the sensitivity of alanine dosemeters to thermal neutrons. Irradiations were carried out inside the thermal column of the TAPIRO reactor of the ENEA center, Casaccia Rome. The main results are a greater neutron sensitivity and a smaller lowest detectable fluence for the dosemeters with gadolinium than for dosemeters of alanine with (10)B, which is well known to be much more sensitive to thermal neutrons than simple alanine. PMID:17517673

Marrale, M; Brai, M; Gennaro, G; Triolo, A; Bartolotta, A; D'Oca, M C; Rosi, G

2007-01-01

93

Determination of the Absolute Value of Absorbed Dose in Tissue-Equivalent Material in Standard Source gamma Field.  

National Technical Information Service (NTIS)

The absolute measurements of main dosimetric parameters in the /sup 60/Co field of ROKUS irradiation device are performed in order to create a standard irradiation field for calibration of medical dosemeters. The measurements were made by means of tissue-...

M. Zel'chinskij

1988-01-01

94

Individual Neutron Dosimetry.  

National Technical Information Service (NTIS)

The most important concepts and development in individual neutron dosimetry are presented, especially the dosimetric properties of the albedo technique. The main problem in albedo dosimetry is to calibrate the dosemeter in the environs of each neutron sou...

C. L. P. Mauricio

1987-01-01

95

Direct ion storage dosimetry systems for photon, beta and neutron radiation with instant readout capabilities.  

PubMed

The direct ion storage (DIS) dosemeter is a new type of electronic dosemeter from which the dose information for both Hp(10) and Hp(0.07) can be obtained instantly at the workplace by using an electronic reader unit. The number of readouts is unlimited and the stored information is not affected by the readout procedure. The accumulated dose can also be electronically reset by authorised personnel. The DIS dosemeter represents a potential alternative for replacing the existing film and thermoluminescence dosemeters (TLDs) used in occupational monitoring due to its ease of use and low operating costs. The standard version for normal photon and beta dosimetry, as well as a developmental version for neutron dosimetry, have been characterised in several field studies. Two new small size variations are also introduced, including a contactless readout device and a militarised version optimised for field use. PMID:11586743

Wernli, C; Kahilainen, J

2001-01-01

96

Quantitative evaluation of personal exposure to UV radiation of workers and general public.  

PubMed

Due to meteorological conditions variability and to the variability of exposure patterns, which can be largely different during a working day, personal dosemeters use can be necessary to obtain a correct quantitative evaluation of the radiation dose absorbed by an exposed worker. Different classes of personal dosemeters exist and, among them, electronic dosemeters and polysulphone film dosemeters. An experimental campaign is presented conduced in a cultivated area of Tuscany and some aspects are discussed about an experimental campaign performed on a population of volunteers on a central Italy beach near Rome. The aim of the present work is to show some relevant issues in a dosimetric approach to the exposure evaluation of outdoor workers and, in general, of the public during recreational activities. PMID:19841017

Sisto, R; Borra, M; Casale, G R; Militello, A; Siani, A M

2009-12-01

97

Calibration of Instrument and Personnel Monitoring in Radiological Protection.  

National Technical Information Service (NTIS)

It is difficult to choose radioprotection equipment that is not too expensive and still suit the purpose. Some of the dosimetric characteristics of good dosemeters outlined by ISO 4071-1978 (E) namely scale linearity, energy dependence, radiation quality ...

A. A. M. Ramli W. S. W. Abdullah

1987-01-01

98

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerologi´a Department of Nuclear Medicine  

Microsoft Academic Search

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerologi´a, 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 Metrologi´a, to known

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

2010-01-01

99

Response of \\  

Microsoft Academic Search

A single crystal of sodium iodide 9-1\\/4 inches in diameter and 9 inches high with the top bevelled at 450 was recently obtained from Harshaw Chemical Company. A half-inch hole was drilled in the bevelled end to the center of the crystal. Three 5-inch diameter Dumont 6364's were optically connected directly to the flat end of the crystal. Sources were

R. C. Davis; P. R. Bell; G. G. Kelley; N. H. Lazar

1956-01-01

100

LET dependence of thermoluminescent efficiency and peak height ratio of CaF 2:Tm  

Microsoft Academic Search

First-order thermoluminescence (TL) kinetics computerized glow curve deconvolution (CGCD) and manual analysis of the composite peak structures have been applied to study the behaviour of glow peaks 3 and 5 in CaF2:Tm (TLD-300, Harshaw-Thermo Fisher Scientific) single crystals after heavy charged particle (HCP) irradiation with respect to Co60 gamma rays for a linear energy transfer (LET) interval from 2.3 to

M. Hajek; T. Berger; R. Bergmann; N. Vana; Y. Uchihori; N. Yasuda; H. Kitamura

2008-01-01

101

Kinetics and mechanism of desulfurization and denitrogenation of coal-derived liquids. Second quarterly report, September 20, 1975December 20, 1975. [Aged CoO-MoO-SiO-AlO catalyst pellets used in single-stage liquefaction and hydrosulfurization of coal  

Microsoft Academic Search

The construction of the first high-pressure liquid-phase flow microreactor has been completed, and kinetic studies of reaction of dibenzothiophene have been started. Understanding of catalytic hydrodesulfurization and catalyst decay has been advanced by examination of the reaction rate of thiophene, tetrahydrothiophene, and butanethiol on Harshaw 0402T catalyst. Two batch autoclave reactors have been completely assembled behind appropriate safety barricades; satisfactory

J. R. Katzer; B. C. Gates; J. H. Olson; H. Kwart; A. B. Stiles

1976-01-01

102

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

PubMed

In view of the introduction of International Commission on Radiation Units and Measurements operational quantities Hp(10) and Hp(0.07), defined for individual monitoring, it became necessary to develop an algorithm that gives direct response of the dosemeter in terms of the operational quantities. Hence, for this purpose and also to improve the accuracy in dose estimation especially in the mixed fields of X ray and gamma, an algorithm was developed based on higher-order polynomial fit of the data points generated from the dose-response of discs under different filter regions of the present TL dosemeter system for known delivered doses. Study on the response of the BARC TL dosemeter system based on CaSO(4):Dy Teflon thermoluminescence dosemeter discs in the mixed fields of X and gamma radiation was carried out to ensure that the accuracies are within the prescribed limits recommended by the international organisations. The prevalent algorithm, based on the ratios of the disc response under various filters regions of the dosemeter to pure photons, was tested for different proportion of two radiations in case of mixed field dosimetry. It was found that the accuracy for few fields is beyond the acceptable limit in case of prevalent algorithm. The new proposed algorithm was also tested in mixed fields of photon fields and to pure photon fields of varied angles. It was found that the response of the dosemeter in mixed fields of photons and its angular response are satisfactory. The new algorithm can be used to record and report the personal dose in terms of Hp(10) as per the international recommendation for the present TL dosemeter. PMID:16984896

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

2007-01-01

103

Thermoluminescent detectors applied in individual monitoring of radiation workers in Europe--a review based on the EURADOS questionnaire.  

PubMed

Among the activities of EURADOS Working Group 2 formed by experts from several European countries is the harmonisation of individual monitoring as part of radiation protection of occupationally exposed persons. Here, we provide information about thermoluminescent detectors (TLDs) applied by the European dosimetric services and the dosimetric characteristics of dosemeters in which these detectors are applied. Among 91 services from 29 countries which responded to the EURADOS questionnaire, 61 apply dosemeters with TLDs for the determination of personal dose equivalent H(p)(10) for photons and beta radiation, and 16 services use TLDs for neutron albedo dosemeters. Those most frequently used are standard lithium fluoride TLDs (mainly TLD-100, TLD-700, Polish MTS-N and MTS-7, Russian DTG-4), high-sensitive lithium fluoride (GR-200, MCP-N) and lithium borate TLDs. Some services use calcium sulphate and calcium fluoride detectors. For neutron dosimetry, most services apply pairs of LiF:Mg,Ti TLDs with (6)Li and (7)Li. The characteristics (energy response) of individual dosemeters are mainly related to the energy response of the detectors and filters applied. The construction of filters in dosemeters applied for measurements of H(p)(10) and their energy response are also reviewed. PMID:16581929

Olko, P; Currivan, L; van Dijk, J W E; Lopez, M A; Wernli, C

2006-01-01

104

TL dose measurements on board the Russian segment of the ISS during Expedition-7 and -8  

NASA Astrophysics Data System (ADS)

The most advanced version of a thermo-luminescent (TL) dosemeter system (``Pille-MKS'') developed by the KFKI Atomic Energy Research Institute (KFKI AEKI), consisting of ten CaSO4:Dy bulb dosemeters and a compact reader, was successfully installed on board the ISS in October, 2003. It is applied for the routine and EVA individual dosimetry of astronauts/cosmonauts as part of the service system as well as for onboard experiments and operated by the Institute for Biomedical Problems (IBMP). It is unique providing accurate and high resolution TL dose data already on board the space station which became increasingly important during the suspension of the Space Shuttle flights. In accordance with the common Russian-American working document ISS 8 IDRD, seven dosemeters are located at several places of the Russian segment of the ISS and read out per month, two dosemeters are dedicated for EVAs and one dosemeter is kept in the reader to be read out automatically every 90 minutes. During particular events like coronal mass ejections, hitting Earth incidental measuring campaigns are intercalated with frequent readouts (twice a day). In this paper we report results of dosimetric measurements made aboard the International Space Station during Expedition-7 and -8 using the Pille portable TLD system. We compare results with TLD measurements made using an identical equipment during the DOSMAP experiment on board the ISS in 2001.

Apáthy, I.; Akatov, Yu. A.; Arkhangelsky, V. V.; Deme, S.; Reitz, G.

105

Czech results at criticality dosimetry intercomparison 2002.  

PubMed

Two criticality dosimetry systems were tested by Czech participants during the intercomparison held in Valduc, France, June 2002. The first consisted of the thermoluminescent detectors (TLDs) (Al-P glasses) and Si-diodes as passive neutron dosemeters. Second, it was studied to what extent the individual dosemeters used in the Czech routine personal dosimetry service can give a reliable estimation of criticality accident exposure. It was found that the first system furnishes quite reliable estimation of accidental doses. For routine individual dosimetry system, no important problems were encountered in the case of photon dosemeters (TLDs, film badge). For etched track detectors in contact with the 232Th or 235U-Al alloy, the track density saturation for the spark counting method limits the upper dose at approximately 1 Gy for neutrons with the energy >1 MeV. PMID:15353690

Frantisek, Spurný; Jaroslav, Trousil

2004-01-01

106

Intercomparison of passive dosimetry technology at EDF facilities in France.  

PubMed

Since the spring of 1999, new French radiation protection legislation has allowed the use of passive dosemeters, other than the silver emulsion film badge, for the measurement of H(p)(10). Faced with the eventual obsolescence of its dosimetry system, Electricité de France (EDF, the French electricity provider) initiated a comparative study of passive dosemeters, based on different technologies, that had received accreditation by national laboratories and regulatory bodies, namely: TLD, RPL and OSL. An extended field study in nuclear power stations and medical X-ray departments has shown that all technologies provide compatible dosimetric estimates. It also showed that the selected dosemeters based on RPL and OSL technologies gave better results due to their energy responses and to a lower detection threshold compliant with the new regulation. A final suggestion to implement a new OSL based dosimetric system is made due to its overall performance and to its lower cost of implementation. PMID:17298953

Garcier, Y; Cordier, G; Pauron, C; Fazileabasse, J

2007-01-01

107

Quality control for exposure assessment in epidemiological studies.  

PubMed

In the framework of an epidemiological study, dosemeters were used for the assessment of radio frequency electromagnetic field exposure. To check the correct dosemeter's performance in terms of consistency of recorded field values over the entire study period, a quality control strategy was developed. In this paper, the concept of quality control and its results is described. From the 20 dosemeters used, 19 were very stable and reproducible, with deviations of a maximum of +/-1 dB compared with their initial state. One device was found to be faulty and its measurement data had to be excluded from the analysis. As a result of continuous quality control procedures, the confidence in the measurements obtained during the field work was strengthened significantly. PMID:20308051

Bornkessel, C; Blettner, M; Breckenkamp, J; Berg-Beckhoff, G

2010-08-01

108

Radon contribution to the total effective dose of uranium miners.  

PubMed

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

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

2014-07-01

109

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

PubMed

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

Asselineau, B; Trompier, F; Texier, C; Itié, C; Médioni, R; Tikunov, D; Muller, H; Pelcot, G

2004-01-01

110

Individual neutron monitoring in workplaces with mixed neutron/photon radiation.  

PubMed

EVIDOS ('evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cask. PMID:15353743

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

2004-01-01

111

A thermoluminescence dosimetry system for personal monitoring in Ireland.  

PubMed

In 1993 the decision was taken to replace film badges with thermoluminescence dosemeters (TLDs) as the main form of dosemeter for both whole-body and extremity monitoring at the Dosimetry Service of the Radiological Protection Institute of Ireland (RPII) in Dublin. A review of commercially available automatic TLD systems was carried out to identify the system which best met the RPII's requirements. This paper describes the dosimetry system used, and, in addition, discusses the problems encountered and how these were addressed. PMID:11586731

Currivan, L; Spain, D; Donnelly, H; Colgan, P A

2001-01-01

112

Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT).  

PubMed

A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF2:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH3CH(NH2)COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT. PMID:15353722

Cecilia, A; Baccaro, S; Cemmi, A; Colli, V; Gambarini, G; Rosi, G; Scolari, L

2004-01-01

113

Some developments in neutron and charged particle dosimetry.  

PubMed

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

Bos, Adrie J J; d'Errico, Francesco

2006-01-01

114

Measurement of fast neutrons produced by high-energy X-ray beams of medical electron accelerators  

Microsoft Academic Search

The fast neutron contamination associated with the 25 MV X-ray beam of a clinical linear accelerator and with the 19 MV X-ray beam of a betatron has been measured at the patient treatment location, using both fission fragment track detectors and silicon diode dosemeters. Measurements are made of the neutron fluence and dose, both in and out of the primary

R. M. Wilenzick; P. R. Almond; G. D. Oliver; C. E. De Almeida

1973-01-01

115

A preliminary study to determine the diagnostic reference level using dose-area product for limited-area cone beam CT  

PubMed Central

Objectives: The aim of this study was to measure the dose–area product (DAP) of limited-area cone beam CT (CBCT) units used by dental offices, and to evaluate the rationale of the DAP with an aid of optically stimulated luminescence (OSL) dosemeter in measuring radiation dose. Method: The DAPs of 21 CBCT units used in the dental offices of Tokyo and the surrounding areas from five different manufacturers were measured using OSL nanoDot dosemeter. An assembly of OSL dosemeters with an X-ray film was exposed by CBCT units at exposure parameters commonly used in each dental office. DAP values were then calculated as expressed in mGy?cm2. Results: DAP values ranged from 126.7?mGy?cm2 to 1476.9?mGy?cm2, depending on the units used. Conclusion: OSL dosemeter coupled with film can be utilized for a large-scale study to measure DAP. The DAP values for individual CBCT units depend not only on the field of view, but also on the exposure parameters adapted by the dental offices.

Endo, A; Katoh, T; Vasudeva, SB; Kobayashi, I; Okano, T

2013-01-01

116

Operational and dosimetric characteristics of etched-track neutron detectors in routine neutron radiation protection dosimetry  

Microsoft Academic Search

There are a number of etched-track neutron dosimetry systems in routine use for personal monitoring. In this paper, the operational and dosimetric characteristics of these systems are summarized. Brief details are given of the dosemeter design, the material used, its quality control procedures, background, processing and read methods, neutron energy range, energy and angle dependence of response, decision threshold, linearity,

R. J. Tanner; D. T. Bartlett; L. G. Hager

2005-01-01

117

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

118

Dose measurements in space by the Hungarian Pille TLD system.  

PubMed

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

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

2002-10-01

119

Personal neutron dosimetry in the space station MIR and the space shuttle  

Microsoft Academic Search

A passive neutron dosemeter based on nuclear track detectors and TLD's was used in 1995 and 1997 on the MIR station and in Space Shuttle flights to MIR. As it is equipped with neutron converters and shieldings of different types the track detector system allows the neutron dose equivalent to be determined in rough energy intervals. The results of the

M. Luszik-Bhadra; M. Matzke; T. Otto; G. Reitz; H. Schuhmacher

1999-01-01

120

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

121

High-sensitivity thermoluminescence applied to environmental monitoring  

NASA Astrophysics Data System (ADS)

We describe the development of a new environmental TLD Dosemeter Badge and dose computation algorithm based on the new LiF:Mg,Cu,P material. LiF:Mg,Cu,P, with its high sensitivity, tissue equivalence, energy independence, and low fading characteristics, is a natural choice for environmental dosimetry. The badge consists of a card and a plastic holder. The card contains four LiF:Mg,Cu,P elements, each 3.2 mm square and 0.4 mm thick, encapsulated in TeflonR. The badge is symmetrical and uses four filters to discriminate low and high energy photons and to determine Directional Dose Equivalent, H'(0.07,(alpha) ), and Ambient Dose Equivalent, H*(10). Extensive data was taken based on irradiations of 920 dosemeters to both single and mixed fields of photons and betas. In addition, angular incidence data of various fields was taken. The approach to the algorithm is empirical and is based on this data. While most algorithms are based solely on perpendicular incidence exposure, this algorithm is being developed to account for the angular response of the dosemeter. This paper will present the algorithm for perpendicular irradiation; the angular response portion is in development. The dosemeter is designed to meet the criteria of the new draft standard ANSI N13.29, 'Environmental Dosimetry Performance -- Criteria for Testing.'

Velbeck, K. J.; Zhang, L.; Rotunda, Joe E.; Moscovitch, Marko

1999-02-01

122

Long-term intercomparison of Spanish environmental dosimetry services. Study of transit dose estimations  

Microsoft Academic Search

This paper presents the layout and results of a three-year follow-up of a national intercomparison campaign organized on a voluntary basis among the Spanish Laboratories in charge of environmental monitoring at and in the vicinity of Spanish nuclear installations. The dosemeters were exposed in the field at an environmental reference station with a known ambient dose equivalent, and controlled meteorological

Ma Amor Duch; Jose Carlos Sáez-Vergara; Mercč Ginjaume; Candelas Gómez; Ana María González-Leitón; Javier Herrero; Ma José de Lucas; Rafael Rodríguez; Immaculada Marugán; Rosario Salas

2008-01-01

123

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.

124

Austrian radiation dose measurements onboard space station mir and the international space station iss - overview and comparison  

NASA Astrophysics Data System (ADS)

The Atominstitut of the Austrian Universities has conducted various space research missions in the last 12 years in cooperation with the Institute for Biomedical Problems in Moscow. They dealt with the exact determination of the radiation hazards for cosmonauts and the development o precise measurement devices.f Special emphasis will be laid on the last experiment on space station MIR the goal of which was the determination of the depth distribution of absorbed dose and dose equivalent in a water filled phantom. The first results from dose measurements onboard the International Space Station will also be discussed.. The phantom with a diameter of 35 cm was developed at the Institute for Biomedical Problems and had 4 channels where dosemeters can be exposed in different depths. The exp osure period covered the timeframe from May 1997 to February 1999. Thermoluminescent dosemeters (TLDs) were exposed inside the phantom, either parallel or perpendicular to the hull of the spacecraft. For the evaluation of the linear energy transfer (LET), the High Temperature Ratio (HTR) - method was applied. Based on this method a mean quality factor and, subsequently, the dose equivalent is calculated according to the Q(LET ) relationship proposed in ICRP 26. An increased contribution of neutrons could be detected inside the phantom. However the total dose equivalent did not increase over the depth of the phantom. As the first Austrian measurements on the ISS dosemeter packages were exposed for 248 days, starting in February 2001 at six different locations onboard the ISS. The Austrian dosemeter sets for this first exposure on the ISS contained 5 different kinds of passive thermoluminescent dosemeters. First results showed a position dependent absorbed dose rate and LET at the ISS. Dose rates ranged from 180 to 280 ?Gy/d. The differences in dose measurements onboard the 2 space stations will be discussed.

Berger, T.; Hajek, M.; Summerer, L.; Vana, N.; Akatov, Y.; Shurshakov, V.; Arkhangelsky, V.

125

Austrian dose measurements onboard space station MIR and the International Space Station - overview and comparison  

NASA Astrophysics Data System (ADS)

The Atominstitute of the Austrian Universities has conducted various space research missions in the last 12 years in cooperation with the Institute for Biomedical Problems in Moscow. They dealt with the exact determination of the radiation hazards for cosmonauts and the development of precise measurement devices. Special emphasis will be laid on the last experiment on space station MIR the goal of which was the determination of the depth distribution of absorbed dose and dose equivalent in a water filled Phantom. The first results from dose measurements onboard the International Space Station (ISS) will also be discussed. The spherical Phantom with a diameter of 35 cm was developed at the Institute for Biomedical Problems and had 4 channels where dosemeters can be exposed in different depths. The exposure period covered the timeframe from May 1997 to February 1999. Thermoluminescent dosemeters (TLDs) were exposed inside the Phantom, either parallel or perpendicular to the hull of the spacecraft. For the evaluation of the linear energy transfer (LET), the high temperature ratio (HTR) method was applied. Based on this method a mean quality factor and, subsequently, the dose equivalent is calculated according to the Q(LET ?) relationship proposed in ICRP 26. An increased contribution of neutrons could be detected inside the Phantom. However the total dose equivalent did not increase over the depth of the Phantom. As the first Austrian measurements on the ISS dosemeter packages were exposed for 248 days, starting in February 2001 at six different locations onboard the ISS. The Austrian dosemeter sets for this first exposure on the ISS contained five different kinds of passive thermoluminescent dosemeters. First results showed a position dependent absorbed dose rate at the ISS.

Berger, T.; Hajek, M.; Summerer, L.; Vana, N.; Akatov, Y.; Shurshakov, V.; Arkhangelsky, V.

2004-01-01

126

Characterisation of the TAPIRO BNCT epithermal facility.  

PubMed

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

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

2004-01-01

127

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

128

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

NASA Astrophysics Data System (ADS)

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

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

2004-01-01

129

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

NASA Astrophysics Data System (ADS)

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

Bero, M. A.

2007-09-01

130

Experimental determination of the dose deposition profile of a 90Sr beta source.  

PubMed

Three different methods for characterising the dose deposition profile of a (90)Sr/(90)Y radioactive source are described: GAFChromic film dosimetry, Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL). For the film measurements, GAFChromic film samples were stacked at different depths between polyethylene terephthalate (PET) foils. For TL, the thickness of a TLD-500 dosemeter was gradually reduced by polishing and the TL from chips of different thickness was used in conjunction with a mathematical model based on the exponential attenuation of dose inside the crystal to determine the decay constant for the dose-depth profile. Finally, an OSL reader with confocal stimulation / detection capabilities was used to map the two-dimensional dose distribution in TLD-500 dosemeters as a function of depth. The shapes of the dose deposition profiles obtained from all the investigated methods are in good agreement. PMID:16644945

Gaza, R; Bulur, E; McKeever, S W S; Soares, C G

2006-01-01

131

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

132

Reassessment of individual dosimetry of long-lived alpha radionuclides of uranium miners through experimental determination of urinary excretion of uranium.  

PubMed

Urinary excretion of uranium of 40 uranium miners was determined by the high-resolution inductively coupled mass spectrometry method. The concentration of uranium in the urine of the miners was converted to daily excretion of (238)U either under the assumption that the daily urinary excretion is 1.6 l or daily urinary excretion of creatinine is 1.7 g and compared with the excretion of (238)U calculated with a biokinetic model. Input data to the excretion model were derived from personal three- component ALGADE dosemeters, using the component for the estimation of inhalation of long-lived alpha radionuclides. Experimentally found contents of uranium in the urine of uranium miners are generally lower than the modelled ones, which means that the dosimetric approach is conservative. The uncertainty of inhalation intakes, derived from the measurements of filters from personal dosemeters, and the uncertainty of the concentration of uranium in the urine are discussed. PMID:22923239

Malátová, I; Becková, V; Tomásek, L; Slezáková-Marusiaková, M; H?lka, J

2013-04-01

133

Content of uranium in urine of uranium miners as a tool for estimation of intakes of long-lived alpha radionuclides.  

PubMed

Uranium in the urine of 10 uranium miners (hewers), 27 members of general population and 11 family members of miners was determined by the High-Resolution ICP-MS method. Concentration of uranium in urine of the miners was converted to daily excretion of (238)U under the assumption that the daily excretion of urine is 2 l and compared with the modelled excretion of (238)U. Daily excretion of (238)U was modelled using input data from personal dosemeters from a component for measurement of intake of long-lived alpha radionuclides. A reasonable agreement between evaluated and measured values was found. The uncertainty of inhalation intakes, derived from measurements of filters from personal dosemeters, and uncertainty of concentration of uranium in urine are discussed. PMID:21208936

Malátová, I; Becková, V; Tomásek, L; Hulka, J

2011-11-01

134

Review of bubble detector response characteristics and results from space.  

PubMed

A passive neutron-bubble dosemeter (BD), developed by Bubble Technology Industries, has been used for space applications. Both the bubble detector-personal neutron dosemeter and bubble detector spectrometer have been studied at ground-based facilities in order to characterise their response due to neutrons, heavy ion particles and protons. This technology was first used during the Canadian-Russian collaboration aboard the Russian satellite BION-9, and subsequently on other space missions, including later BION satellites, the space transportation system, Russian MIR space station and International Space Station. This paper provides an overview of the experiments that have been performed for both ground-based and space studies in an effort to characterise the response of these detectors to various particle types in low earth orbit and presents results from the various space investigations. PMID:21890528

Lewis, B J; Smith, M B; Ing, H; Andrews, H R; Machrafi, R; Tomi, L; Matthews, T J; Veloce, L; Shurshakov, V; Tchernykh, I; Khoshooniy, N

2012-06-01

135

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

136

Quality assurance and quality control programme in the Personal Dosimetry Department of the Greek Atomic Energy Commission.  

PubMed

A quality assurance (QA) and quality control (QC) programme was applied to the personal monitoring department (TLD based) of the Greek Atomic Energy Commission (GAEC). This programme was designed according to the recommendations of international bodies such as the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), the International Atomic Energy Agency (IAEA) and the European Commission (CEC). This paper deals with the presentation of the QA/QC programme which includes administrative data and information, technical checking of the equipment, acceptance tests of new equipment and dosemeters, issuing and processing of the dosemeters, dose evaluation, record keeping and reporting, traceability and reproducibility, handling of complaints, internal reviews and external audits. PMID:12382742

Kamenopoulou, V; Drikos, G; Carinou, E; Papadomarkaki, E; Askounis, P; Kyrgiakou, H; Kefalonitis, N

2002-01-01

137

A practical method to evaluate radiofrequency exposure of mast workers.  

PubMed

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

Alanko, Tommi; Hietanen, Maila

2008-01-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2002-01-01

139

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

140

IEC STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION  

SciTech Connect

This paper presents IEC/SC 45B Radiation protection instrumentation and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

Voytchev, Miroslav [IRSN; Ambrosi, P. [Physikalisch-Technische Bundesanstalt (PTB); Behrens, R. [Physikalisch-Technische Bundesanstalt (PTB); Chiaro Jr, Peter John [ORNL

2011-01-01

141

Overview of novel techniques for radiation protection and dosimetry  

Microsoft Academic Search

Generally, the main approaches for assessing the radiation protection (RP) quantities in neutron fields are: i) the use of an instrument with a response to the protection quantity quasi-independent of energy; ii) neutron spectrometry; iii) microdosimetry.The techniques based on the first approach include rem-meters, superheated emulsions and the electronic personal dosemeters. Passive rem-meters have recently been developed for assessing the

Stefano Agosteo

2010-01-01

142

Monitoring environmental dose rate using Risř TL\\/OSL readers with built-in sources: recommendations for users  

Microsoft Academic Search

Measurements were carried out to quantify the dose rate delivered to samples due to leakage and cross-talk of the beta and alpha sources in various models of Risř TL\\/OSL readers; additionally the offset time was calculated. Highly sensitive ?-Al2O3:C and CaF2:Mn dosemeters were used to investigate the impact on low environmental dose-rate assessment. The effect is shown to depend on

R. Kalchgruber; H. Y. Göksu; E. Hochhäuser; G. A. Wagner

2002-01-01

143

C? and CE values (dosimetry)  

Microsoft Academic Search

An MEL (SL75\\/20) linear accelerator, an absorbed dose calorimeter and ferrous sulphate have been used to obtain absorbed dose correction factors, Clambda and CE, for use with a Farmer ionisation chamber. The calorimeter is a twin quasi-adiabatic graphite absorber type and has been used for the measurement of 8 and 16 MV X-rays. The Fricke Dosemeter Reference Service of the

G Pitchford; M Bidmead

1978-01-01

144

The use of gel dosimetry to measure the 3D dose distribution of a 90Sr\\/90Y intravascular brachytherapy seed  

Microsoft Academic Search

Absorbed dose distributions in 3D imparted by a single 90Sr\\/90Y beta particle seed source of the type used for intravascular brachytherapy were investigated. A polymer gel dosimetry medium was used as a dosemeter and phantom, while a special high-resolution laser CT scanner with a spatial resolution of 100 µm in all dimensions was used to quantify the data. We have

G Massillon-JL; R Minniti; M G Mitch; M J Maryanski; C G Soares

2009-01-01

145

Neutron beam dosimetry at the NRL cyclotron  

Microsoft Academic Search

A 35 MeV deuteron beam impinging upon a thick Be target is being employed to generate a neutron beam for radiobiological experiments of relevance to later possible fast neutron therapy trials. The primary calibration of the beam has been based upon tissue-equivalent plastic ionization chambers, calibrated in turn with 60Co gamma -rays. CaF2:Mn and 7LiF (TLD-700) thermoluminescent dosemeters have been

F. H. Attix; R. B. Theus; P. Shapiro; R. E. Surratt; A. E. Nash; S. G. Gorbics

1973-01-01

146

TL measurement of ambient dose at a Nuclear Medicine Department  

Microsoft Academic Search

An investigation of ambient dose at the Nuclear Medicine Department, Instituto Nacional de Cancerologěa, Mexico, was performed using two types of thermoluminescent dosemeters: TLD-100 and TLD-900. In addition, ambient dose was measured at the outside corridor of the hospitalization room for 137Cs brachytherapy patients. Radionuclides used at the Nuclear Medicine Department are 131I, 18F, 67Ga, 99mTc, 111In, 201Tl. Main gamma

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

147

Measurement of acid site density on molybdenum sulfide  

SciTech Connect

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

Hou, P.; Wise, H.

1982-12-01

148

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

SciTech Connect

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

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

1994-10-01

149

ESR and TL dosimetry systems: comparative measurements for human phantom.  

PubMed

Mixtures of small fragments of tooth enamel as well as thermoluminescence (TL) dosimeters were placed into the tissue-equivalent phantom of the human head with skeleton (approximately at the level of the jaws) and irradiated using 137Cs low dose-rate gamma therapeutic sources ('SELEKTRON' LDR 137Cs). Phantom, samples of teeth and TL detectors were irradiated behind water tank to produce scattered irradiation. The same irradiation with the same geometry was performed in air too. For gamma-spectrometry 137Cs sources with very low activity were used but with the same geometry as therapeutic sources. The absorbed dose in enamel was estimated with the help of ESR spectrometer 'ESP-300 E' (Brucker). The samples of tooth enamel were partially used for preliminary dose evaluation by ESR signal before starting of experiment. TL dosimetry was performed by TL reader model 8800 (HARSHAW) using TL dosimeters calibrated with 137Cs. The paper presents data obtained in comparative aspects. PMID:9022197

Stepanenko, V F; Skvortsov, V G; Ivannikov, A I; Kondrashov, A E; Vaichulis, P P; Denisenko, O N; Kozlov, V A; Khamidova, L G; Tikunov, D D; Panfilov, A P; Eichhozff, U

1996-01-01

150

Application of the high-temperature ratio method for evaluation of the depth distribution of dose equivalent in a water-filled phantom on board space station Mir.  

PubMed

A water-filled tissue equivalent phantom with a diameter of 35 cm was developed at the Institute for Biomedical Problems. Moscow. Russia. It contains four channels perpendicular to each other, where dosemeters can be exposed at different depths. Between May 1997 and February 1999 the phantom was installed at three different locations on board the Mir space station. Thermoluminescence dosemeters (TLDs) were exposed at various depths inside the phantom either parallel or perpendicular to the hull of the spacecraft. The high-temperature ratio (HTR) method was used for the evaluation of the TLDs. The method was developed at the Atominstitute of the Austrian Universities. Vienna, Austria, and has already been used for measurements in mixed radiation fields on earth and in space with great success. It uses the changes of peak height ratios in LiF:Mg,Ti glow curves in dependence on the linear energy transfer (LET), and therefore allows determination of an 'averaged' LET as well as measurement of the absorbed dose. A mean quality factor and, subsequently, the dose equivalent can be calculated according to the Q(LETinfinity) relationship proposed by the ICRP. The small size of the LiF dosemeters means that the HTR method can be used to determine the gradient of absorbed dose and dose equivalent inside the tissue equivalent body. PMID:12382930

Berger, T; Hajek, M; Schöner, W; Fugger, M; Vana, N; Akatov, Y; Shurshakov, V; Arkhangelsky, V; Kartashov, D

2002-01-01

151

Chemical dosimetry system for criticality accidents.  

PubMed

Ruder Boskovi? Institute (RBI) criticality dosimetry system consists of a chemical dosimetry system for measuring the total (neutron + gamma) dose, and a thermoluminescent (TL) dosimetry system for a separate determination of the gamma ray component. The use of the chemical dosemeter solution chlorobenzene-ethanol-trimethylpentane (CET) is based on the radiolytic formation of hydrochloric acid, which protonates a pH indicator, thymolsulphonphthalein. The high molar absorptivity of its red form at 552 nm is responsible for a high sensitivity of the system: doses in the range 0.2-15 Gy can be measured. The dosemeter has been designed as a glass ampoule filled with the CET solution and inserted into a pen-shaped plastic holder. For dose determinations, a newly constructed optoelectronic reader has been used. The RBI team took part in the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002, with the CET dosimetry system. For gamma ray dose determination TLD-700 TL detectors were used. The results obtained with CET dosemeter show very good agreement with the reference values. PMID:15353694

Miljani?, Saveta; Ilijas, Boris

2004-01-01

152

ESR/alanine dosimetry applied to radiation processing  

NASA Astrophysics Data System (ADS)

The radiation processing of food products is specified in terms of absorbed dose, and processing quality is assessed on the basis of absorbed dose measurements. The validity of process quality control is highly dependent on the quality of the measurements and associated instrumentation; in this respect, dosimetry calibration by an Organization with official status provides an essential guarantee of validity to the quality control steps taken. The Laboratoire de Métrologie des Rayonnements Ionisants (L.M.R.I.) is the primary standards and evaluation laboratory approved by the Bureau National de Métrologie (B.N.M.), which is the French National Bureau of Standards. The LMRI implements correlation procedures in response to the various requirements which arise in connection with high doses and doserates. Such procedures are mainly based on ESR/alanine spectrometry, a dosimetry technique ideally suited to that purpose. Dosemeter geometry and design are tailored to operating conditions. "Photon" dosemeters consist of a detector material in powder or compacted form, and a wall with thickness and chemical composition consistent with the application. "Electron" dosemeters have a detector core of compacted alanine with thickness down to a few tenths of a millimeter. The ESR/alanine dosimetry technique, developed at LMRI is a flexible, reliable and accurate tool which effectively meets the various requirements arising in the field of reference dosimetry, where high doses and doserates are involved.

Mosse, D. C.

153

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

154

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.

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

2013-01-01

155

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

156

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

SciTech Connect

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

Avila, O. [Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, DF (Mexico); Torres-Ulloa, C. L. [Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, DF (Mexico); Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, AP 70-542, 04510, DF (Mexico); Medina, L. A. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, 01000, DF (Mexico); Unidad de Investigacion Biomedica en Cancer INCan-UNAM, Av. San Fernando 22 C.P. 14080 (Mexico); Trujillo-Zamudio, F. E. [Instituto Nacional de Cancerologia (INCan), Av. San Fernando 22, C.P. 14080 (Mexico); Gamboa de Buen, I. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, AP 70-543, 04510 DF (Mexico); Buenfil, A. E.; Brandan, M. E. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, 01000, DF (Mexico)

2010-12-07

157

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

158

Analiza niepewno?ci pomiaru wspó?czynnika wzorcowania dawkomierzy terapeutycznych i diagnostycznych, wzorcowanych w polskim Laboratorium Wtórnych Wzorców Dozymetrycznych  

NASA Astrophysics Data System (ADS)

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

Ulkowski, Piotr; Bulski, Wojciech; Gwiazdowska, Barbara

2011-01-01

159

Natural gamma radioactivity in the villages of Kanyakumari District, Tamil Nadu, India.  

PubMed

In situ radiometric survey carried out in 81 revenue villages of Kanyakumari District, Tamil Nadu, India, using a portable radiation dosemeter/detector, revealed the existence of radiation hotspots along the coastal belt. A close observation of the coastal villages specifically revealed high background radioactivity in 14 coastal villages. A very high intrinsic anomalous radioactivity of 41.03 ?Sv h(-1) was observed, in a famous tourist spot in the coastal belt of Kanyakumari District. This is the highest level of radiation registered in South India, which is extremely higher than the permissible world average and is suggestive of causing severe clinical problems on continuous and prolonged exposure. PMID:23516264

Padua, Jeni Chandar; Basil Rose, M R

2013-01-01

160

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

PubMed

The Monte Carlo simulation programs PENELOPE and MCNPX have been used for simulating the dose rate distribution in a (60)Co 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 values and the measurements indicates the effectiveness of both codes in performing the dose-mapping simulation for gamma irradiators. PMID:18222694

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

2008-04-01

161

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

PubMed

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

Kim, Hee Geun; Kong, Tae Young

2012-12-01

162

A review of exposures to radon, long-lived radionuclides and external gamma at the Czech uranium mine.  

PubMed

This paper presents the results of the personal exposure monitoring conducted in the RoŽná uranium mine in the Czech Republic. In this mine, which has been operated since the late 1950s, personal ALGADE dosemeters have been used since 1998. A group of 600 miners employed during the period 2000-09 has been analysed. Annual exposures to radon decay products, long-lived alpha emitters and external gamma radiation are described. These components play an essential role in the estimation of the total effective dose. The dependence of the exposures on the type of mining job is also assessed. PMID:21471123

Marušiaková, M; Gregor, Z; Tomášek, L

2011-05-01

163

Measurement of dose-width product in panoramic dental radiology.  

PubMed

The National Radiological Protection Board has recommended the introduction of dose-width product (DWP) for the measurement of patient dose in panoramic dental radiology. The present work describes a method for measuring DWP using a pencil ionization chamber. The technique was tested on five panoramic dental units; the reproducibility of the method was 5.7%. In order to test the method, DWP was also assessed using thermoluminescent dosemeters and film. The results obtained agreed within 8.6% with those obtained using the pencil ionization chamber method. The proposed method appears to be simple and precise. PMID:12642282

Isoardi, P; Ropolo, R

2003-02-01

164

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

NASA Astrophysics Data System (ADS)

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

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

165

Computed Tomography: Image and Dose Assessment  

NASA Astrophysics Data System (ADS)

In this work an experimental evaluation of image quality and dose imparted during a computed tomography study in a Public Hospital in Mexico City is presented; The measurements required the design and construction of two phantoms at the Institute of Physics, UNAM, according to the recommendations of American Association of Physicists in Medicine (AAPM). Image assessment was performed in terms the spatial resolution and image contrast. Dose measurements were carried out using LiF: Mg,Ti (TLD-100) dosemeters and pencil-shaped ionisation chamber; The results for a computed tomography head study in single and multiple detector modes are presented.

Valencia-Ortega, F.; Ruiz-Trejo, C.; Rodríguez-Villafuerte, M.; Buenfil, A. E.; Mora-Hernández, L. A.

2006-09-01

166

Spectrometry and dosimetry of a neutron source  

NASA Astrophysics Data System (ADS)

Using the Monte Carlo methods, the spectrum, dose equivalent and ambient dose equivalent of a 239PuBe have been determined at several distances. The spectrum and both doses were determined to 100 cm with a Bonner sphere spectrometer. These quantities were obtained by unfolding the spectrometer count rates using artificial neural networks. The dose equivalent was measured with the area neutron dosemeter Eberline model NRD, to 100, 200 and 300 cm. All the measurements were carried out in an open space to avoid the room-return. With these results, it was found that this source has a yield of 8.41E(6) n/s.

Vega-Carrillo, H. R.; Manzanares-Acuńa, E.; Hernández-Dávila, V. M.; González, J. Ramírez; Villasana, R. Hernández; Ruiz, A. Chacón

167

Computed Tomography: Image and Dose Assessment  

SciTech Connect

In this work an experimental evaluation of image quality and dose imparted during a computed tomography study in a Public Hospital in Mexico City is presented; The measurements required the design and construction of two phantoms at the Institute of Physics, UNAM, according to the recommendations of American Association of Physicists in Medicine (AAPM). Image assessment was performed in terms the spatial resolution and image contrast. Dose measurements were carried out using LiF: Mg,Ti (TLD-100) dosemeters and pencil-shaped ionisation chamber; The results for a computed tomography head study in single and multiple detector modes are presented.

Valencia-Ortega, F.; Ruiz-Trejo, C.; Rodriguez-Villafuerte, M.; Buenfil, A. E. [Instituto de Fisica, UNAM, A.P. 20-364, D.F. 01000 (Mexico); Mora-Hernandez, L. A. [Hospital de Oncologia, Centro Medico Nacional Siglo XXI, 06720, D.F. (Mexico)

2006-09-08

168

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

NASA Astrophysics Data System (ADS)

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

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

1994-12-01

169

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

PubMed

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

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

2013-01-01

170

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

PubMed

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

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

2011-03-01

171

Neutron response of the chlorobenzene-ethanol-trimethylpentane dosimetry system.  

PubMed

The dosimetric use of the chemical solution chlorobenzene-ethanol-trimethylpentane (CET) is based on the radiolytic formation of hydrochloric acid, which protonates a pH indicator thymolsulphonphthalein. On the basis of the CET solution, an accident and emergency personal dosemeter was designed allowing doses in the range 0.2-15 Gy can be measured. Radiation-chemical yields, G(HCl), for the CET system, and the responses of dosemeters in different neutron fields, ranging from 0.35 to 19.3 MeV mean energy neutrons, are summarised. The relation of G(HCl) to linear energy transfer (LET) of incident heavy charged particles is also evaluated on the basis of the previously published data. The response of the CET system to monoenergetic neutrons was calculated from the measured dependence of the G value upon LET of heavy charged particles and data about the LET distribution for monoenergetic neutrons. A very good agreement between this calculation and the experimental results was obtained. These results enable predictions of the response to be made in radiation fields with the known LET distributions. PMID:17522040

Miljani?, S; Razem, D

2007-01-01

172

Personal dosimetry for interventional operators: when and how should monitoring be done?  

PubMed Central

Objective Assessment of the potential doses to the hands and eyes for interventional radiologists and cardiologists can be difficult. A review of studies of doses to interventional operators reported in the literature has been undertaken. Methods Distributions for staff dose to relevant parts of the body per unit dose–area product and for doses per procedure in cardiology have been analysed and mean, median and quartile values derived. The possibility of using these data to provide guidance for estimation of likely dose levels is considered. Results Dose indicator values that could be used to predict orders of magnitude of doses to the eye, thyroid and hands from interventional operator workloads have been derived, based on the third quartile values, from the distributions of dose results analysed. Conclusion Dose estimates made in this way could be employed in risk assessments when reviewing protection and monitoring requirements. Data on the protection provided by different shielding and technique factors have also been reviewed to provide information for risk assessments. Recommendations on the positions in which dosemeters are worn should also be included in risk assessments, as dose measurements from suboptimal dosemeter use can be misleading.

Martin, C J

2011-01-01

173

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

174

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

175

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

PubMed

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

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

2004-01-01

176

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

PubMed

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

Garnica-Garza, H M

2009-03-21

177

Correlation of optically stimulated luminescence and thermoluminescence of Al 2O 3:Fe, Mg, Cr crystals  

NASA Astrophysics Data System (ADS)

Optically Stimulated Luminescence (OSL) is a technique with increasing application in radiation dosimetry. Here we present the OSL properties of an aluminum oxide single crystal, with impurities of Cr, Mg and Fe, and the correlation of the OSL signal with the thermoluminescent (TL) emission of this material. The results show a TL glow curve with at least four peaks (110, 160, 225 and 270 °C, at 5 °C s -1), with the first one fading rapidly at room temperature. As far as OSL is concerned, a high-intensity signal was observed, comparable to the signal obtained with the known OSL dosemeter Al 2O 3:C. There is a rapid fading of this signal, which becomes stable, with 60% of the initial intensity, after a 1000 s waiting time. The correlation of results obtained with both techniques indicates that illumination with blue light empties almost completely the first and both the highest temperature TL peaks, and moderately the most intense peak (at 160 °C). This fact is commensurate with the fading of the OSL signal, pointing to a relation of the most stable part of the signal with the high-temperature TL peaks, and showing that the shallow traps (related to the lowest temperature TL peak) contribute to the less stable OSL signal. In conclusion, our results state that this crystal can be used as a radiation OSL or TL dosemeter, if care is taken with immediate fading.

Yoshimura, E. M.

2007-09-01

178

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

179

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

PubMed

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

Behrens, R

2010-03-01

180

Book Review:  

NASA Astrophysics Data System (ADS)

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

Burns, J. F.

1984-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

183

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

SciTech Connect

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

McCormick, R.L.

1988-01-01

184

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

SciTech Connect

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

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

1987-07-01

185

BGO suppressed gamma detector arrays  

NASA Astrophysics Data System (ADS)

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

Tabor, S. L.

186

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

NASA Astrophysics Data System (ADS)

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

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

2007-07-01

187

Thermoluminescence properties of CVD diamond films  

NASA Astrophysics Data System (ADS)

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

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

2003-09-01

188

Mixed-radiation discrimination using thermoluminescent dosimeters  

NASA Astrophysics Data System (ADS)

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

Skopec, Marlene

189

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

190

Green stimulated luminescence of ZrO 2 + PTFE to UV radiation dosimetry  

NASA Astrophysics Data System (ADS)

The use of optically stimulated luminescence (OSL) as a method for the determination of environmental radiation absorbed dose using solid state materials has become the main interest of the most great research centers. The aim of this work is to study some dosimetric characteristics of ZrO 2 to be used as a UVR dosemeter by using the OSL method. The most attractive characteristic of ZrO 2 is its very high intrinsic sensitivity to UV radiation. Optical characteristics of ZrO 2 were also studied. OSL typical decay was obtained. OSL response of ZrO 2 samples as a function of irradiation time was linear in the range of 30-1000 s. Experimental results showed that ZrO 2 exhibit attractive characteristics which make it suitable for UV dosimetry applications.

Rivera, T.; Azorín, J.; Furetta, C.; Falcony, C.; García, M.; Martínez, E.

2004-01-01

191

Combined TL and 10B-alanine ESR dosimetry for BNCT.  

PubMed

The dosimetric technique described in this paper is based on electron spin resonance (ESR) detectors using an alanine-boric compound acid enriched with (10)B, and beryllium oxide thermoluminescent (TL) detectors; with this combined dosimetry, it is possible to discriminate the doses due to thermal neutrons and gamma radiation in a mixed field. Irradiations were carried out inside the thermal column of a TRIGA MARK II water-pool-type research nuclear reactor, also used for Boron Neutron Capture therapy (BNCT) applications, with thermal neutron fluence from 10(9) to 10(14) nth cm(-2). The ESR dosemeters using the alanine-boron compound indicated ESR signals about 30-fold stronger than those using only alanine. Moreover, a negligible correction for the gamma contribution, measured with TL detectors, almost insensitive to thermal neutrons, was necessary. Therefore, a simultaneous analysis of our TL and ESR detectors allows discrimination between thermal neutron and gamma doses, as required in BNCT. PMID:15353720

Bartolotta, A; D'Oca, M C; Lo Giudice, B; Brai, M; Borio, R; Forini, N; Salvadori, P; Manera, S

2004-01-01

192

Harmonisation (legal, dosimetric, quality aspects) of individual monitoring, and integration of monitoring for external and internal exposures (EURADOS Working Group).  

PubMed

The EURADOS Working Group II on 'Harmonisation of individual monitoring' consists of experts from almost all EU Member States and Newly Associated States (NAS), involved in tasks related to the assessment of doses for internal and external radiation. The final objective is to achieve harmonisation in individual monitoring for occupational exposures. Sub-group 2 activities are focused on investigating how the results from personal dosemeters for external radiation and workplace monitoring and from monitoring for internal exposure can be combined into a complete and consistent system of individual monitoring. Three questionnaires were prepared, covering 'Individual monitoring of external radiation' (Questionnaire 1), 'Internal exposure' (Questionnaire 2) and 'Natural sources of radiation at the workplace' (Questionnaire 3). With the agreement of a 'contact-person', selected in each country, the distribution of the three EURADOS 2002 questionnaires was carried out by e-mail among the dosimetry facilities of 28 European countries. The preliminary results of these actions are presented here. PMID:14527044

Lopez, M A; Currivan, L; Falk, R; Olko, P; Wernli, C; Castellani, C M; van Dijk, J W E

2003-01-01

193

Aspects of harmonisation of individual monitoring for external radiation in Europe: conclusions of a EURADOS action.  

PubMed

Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accreditation and approval procedures has been compiled. The catalogue of dosimetric services has been updated and extended. An overview of national regulations and standards for protection from radon and other natural sources in workplaces has been made, attempting to combine the results from individual monitoring for external, internal and workplace monitoring. A first status description of the active personal dosemeters, including legislative and technical information, and their implementation has been made. The importance of practical factors on the uncertainty in the dose measurement has been estimated. Even if a big progress has been made towards harmonisation, there is still work to be done. PMID:16581923

Kamenopoulou, V; van Dijk, J W E; Ambrosi, P; Bolognese-Milsztajn, T; Castellani, C M; Currivan, L; Falk, R; Fantuzzi, E; Figel, M; Alves, J Garcia; Ginjaume, M; Janzekovic, H; Kluszczynski, D; Lopez, M A; Luszik-Bhadra, M; Olko, P; Roed, H; Stadtmann, H; Vanhavere, F; Vartiainen, E; Wahl, W; Weeks, A; Wernli, C

2006-01-01

194

Long-term measurements of H*(10) at aviation altitudes in the northern hemisphere.  

PubMed

Monitoring the radiation field at aviation altitudes is achieved by the dosemeter system piDOS installed in a passenger aircraft. The basic detector is a 2 in. tissue-equivalent proportional counter (TEPC) mounted in a cabin-baggage-sized aluminium suitcase. The entire system was characterised in neutron and photon reference fields from which two calibration factors were determined according to the splitting of the measured dose deposition spectrum yd(y) into low-LET and high-LET regions. A total of 255 flights in the northern hemisphere was analysed. The dependencies of the ambient dose equivalent rates on altitude, latitude and solar activity have been determined. These new data extend the data base used in Germany for the validation of program codes to calculate the radiation exposure of air crew members. PMID:16698966

Wissmann, F

2006-01-01

195

Neutron ESR dosimetry through ammonium tartrate with low Gd content.  

PubMed

This paper continues analyses on organic compounds for application in neutron dosimetry performed through electron spin resonance (ESR). Here, the authors present the results obtained by ESR measurements of a blend of ammonium tartrate dosemeters and gadolinium oxide (5 % by weight). The choice of low amount of Gd is due to the need of improving neutron sensitivity while not significantly influencing tissue equivalence. A study of the effect of gadolinium presence on tissue equivalence was carried out. The experiments show that the neutron sensitivity is enhanced by more than an order of magnitude even with this small additive content. Monte Carlo simulations on the increment of energy release due to gadolinium presence were carried, and the results were in good agreement with the experimental data. PMID:24795394

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

2014-06-01

196

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

197

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

198

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

199

The thermoluminescence efficiency of Li2B4O7:Cu and of CaSO4:Tm for photons.  

PubMed

The intrinsic thermoluminescence (TL) efficiency of a TL detector relates the absorbed dose in the detector material to the light yield observed upon evaluation. Knowledge of the TL efficiency is of interest when performing numerical simulations of detector response, where only absorbed dose can be predicted. Here, the experimental determination of TL efficiency for calcium sulphate (CaSO(4):Tm) and lithium borate (Li(2)B(4)O(7):Cu) is reported. These materials are widely used in Panasonic dosemeter badges. The results of the study are in agreement with predictions from track structure theory and microdosimetry, relating an enhanced light yield at low X-ray energies to supralinear behaviour of the TL phosphor. PMID:21183547

Otto, Th; Gindraux, L; Strasser, M

2011-03-01

200

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

201

Use of statistical checks as maintenance tools for TLD readers.  

PubMed

Although the values of different parameters may remain within permissible limits during the operation of a thermoluminescent dosemeter (TLD) reader, certain effects can become apparent only when a long-term followup of these parameters is performed. In order to ensure an accurate and reliable operation of a TLD reader, the system characteristics must be monitored continuously. Long-term statistical checks of key system parameters may give a broader insight into the operational characteristics of the TLD reader and may help for proper maintenance of the system. The photomultipliers noise, the internal reference light source stability and the A to D reference voltage were found to be critical parameters, which have a major influence on the accuracy and stability of the system. A followup of these parameters for a period of about 10 y is presented, and some problems are seen to be reflected in the distributions. PMID:17533159

Weinstein, M; Shemesh, Y; Abraham, A; German, U

2007-01-01

202

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

203

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

204

Dosimetric investigations on Mars-96 mission.  

PubMed

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

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

1994-10-01

205

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

206

A simple method to correct for the temperature lag in TL glow-curve measurements  

NASA Astrophysics Data System (ADS)

Temperature lags between the heating element and the sample are known to exists during a thermoluminescence measurement. The experimental difficulties associated with the temperature lag can be quite serious, when one wants to extract physical information from the glow curves, because it is obviously essential to know the sample's temperature rather than that of the heating element. In the present work approximate relations to estimate the temperature lag between the heating element and the dosemeter and the effective heating rate 0022-3727/31/16/017/img5 across the sample are proposed. Preliminary experimental tests of the proposed equations are performed on LiF:Mg, Ti and 0022-3727/31/16/017/img6 and on data taken from the literature.

Kitis, G.; Tuyn, J. W. N.

1998-08-01

207

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

PubMed

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

Nakamura, T; Tonoike, K; Miyoshi, Y

2004-01-01

208

Applicability of an exposure model for the determination of emissions from mobile phone base stations.  

PubMed

Applicability of a model to estimate radiofrequency electromagnetic field (RF-EMF) strength in households from mobile phone base stations was evaluated with technical data of mobile phone base stations available from the German Net Agency, and dosimetric measurements, performed in an epidemiological study. Estimated exposure and exposure measured with dosemeters in 1322 participating households were compared. For that purpose, the upper 10th percentiles of both outcomes were defined as the 'higher exposed' groups. To assess the agreement of the defined 'higher' exposed groups, kappa coefficient, sensitivity and specificity were calculated. The present results show only a weak agreement of calculations and measurements (kappa values between -0.03 and 0.28, sensitivity between 7.1 and 34.6). Only in some of the sub-analyses, a higher agreement was found, e.g. when measured instead of interpolated geo-coordinates were used to calculate the distance between households and base stations, which is one important parameter in modelling exposure. During the development of the exposure model, more precise input data were available for its internal validation, which yielded kappa values between 0.41 and 0.68 and sensitivity between 55 and 76 for different types of housing areas. Contrary to this, the calculation of exposure-on the basis of the available imprecise data from the epidemiological study-is associated with a relatively high degree of uncertainty. Thus, the model can only be applied in epidemiological studies, when the uncertainty of the input data is considerably reduced. Otherwise, the use of dosemeters to determine the exposure from RF-EMF in epidemiological studies is recommended. PMID:18676976

Breckenkamp, J; Neitzke, H P; Bornkessel, C; Berg-Beckhoff, G

2008-01-01

209

Effect of leaded glasses and thyroid shielding on cone beam CT radiation dose in an adult female phantom  

PubMed Central

Objectives: This study aims to demonstrate the effectiveness of leaded glasses in reducing the lens of eye dose and of lead thyroid collars in reducing the dose to the thyroid gland of an adult female from dental cone beam CT (CBCT). The effect of collimation on the radiation dose in head organs is also examined. Methods: Dose measurements were conducted by placing optically stimulated luminescent dosemeters in an anthropomorphic female phantom. Eye lens dose was measured by placing a dosemeter on the anterior surface of the phantom eye location. All exposures were performed on one commercially available dental CBCT machine, using selected collimation and exposure techniques. Each scan technique was performed without any lead shielding and then repeated with lead shielding in place. To calculate the percent reduction from lead shielding, the dose measured with lead shielding was divided by the dose measured without lead shielding. The percent reduction from collimation was calculated by comparing the dose measured with collimation to the dose measured without collimation. Results: The dose to the internal eye for one of the scans without leaded glasses or thyroid shield was 0.450?cGy and with glasses and thyroid shield was 0.116?cGy (a 74% reduction). The reduction to the lens of the eye was from 0.396?cGy to 0.153?cGy (a 61% reduction). Without glasses or thyroid shield, the thyroid dose was 0.158?cGy; and when both glasses and shield were used, the thyroid dose was reduced to 0.091?cGy (a 42% reduction). Conclusions: Collimation alone reduced the dose to the brain by up to 91%, with a similar reduction in other organs. Based on these data, leaded glasses, thyroid collars and collimation minimize the dose to organs outside the field of view.

Goren, AD; Prins, RD; Dauer, LT; Quinn, B; Al-Najjar, A; Faber, RD; Patchell, G; Branets, I; Colosi, DC

2013-01-01

210

An investigation of gamma background radiation in Hamadan province, Iran.  

PubMed

The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO(4):Dy thermoluminecense dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate  outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22  and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in  Hamadan province. PMID:22570508

Rostampour, Nima; Almasi, Tinoosh; Rostampour, Masoumeh; Mohammadi, Mohammad; Ghazikhanlou Sani, Karim; Khosravi, Hamid R; Pooya, S Mehdi Hosseini; Golzar, Bahman; Jabari Vesal, Naghi

2012-12-01

211

Free Air CO2 Enrichment (FACE) Research Data from the Aspen FACE Experiment (FACTS II)  

DOE Data Explorer

DOE has conducted trace gas enrichment experiments since the mid 1990s. The FACE Data Management System is a central repository and archive for Free-Air Carbon Dioxide Enrichment (FACE) data, as well as for the related open-top chamber (OTC) experiments. FACE Data Management System is located at DOE’s Carbon Dioxide Information Analysis Center (CDIAC). While the data from the various FACE sites, each one a unique user facility, are centralized at CDIAC, each of the FACE sites presents its own view of its activities and information. For that reason, DOE Data Explorer users are advised to see both the central repository at http://public.ornl.gov/face/index.shtml and the individual home pages of each site. FACTS II, the Aspen FACE Experiment is a multidisciplinary study to assess the effects of increasing tropospheric ozone and carbon dioxide levels on the structure and function of northern forest ecosystems. The Aspen FACE facility is located at the Harshaw Experimental Forest near Rhinelander, Wisconsin. It consists of twelve 30m rings in which the concentrations of carbon dioxide and tropospheric ozone can be controlled. The design provides the ability to assess the effects of these gasses alone, and in combination, on many ecosystem attributes, including growth, leaf development, root characteristics, and soil carbon. Each ring consists of a series of vertical ventpipes which disperse carbon dioxide, ozone or normal air into the center of the ring. This computer controlled system uses signal feedback technology to adjust gas release each second in order to maintain a stable, elevated concentration of carbon dioxide and/or ozone throughout the experimental plot. Because there is no confinement, there is no significant change in the natural, ambient environment other than elevating these trace gas concentrations. [copied from http://aspenface.mtu.edu/index.html] Ring maps, lists of publications, data from the experiments, newsletters, protocol and performance information, and links to other FACTS and FACE information are provided at the ASPEN FACE website.

212

Orthodontic radiographic procedures--how safe are they?  

PubMed

Parents of children subjected to radiographic procedures for orthodontic purposes occasionally express concern about possible radiation overdose to sensitive structures in the head and neck region. The following study was designed to determine this. Twenty Harshaw lithium fluoride thermoluminescent dosimeters (TLDs) were irradiated using a calibrated RT 100 X-ray source. These were read in a Toledo 654 TLD reader. The readings of all dosimeters fell within 10% on either side of the mean reading for the dosimeters. Twelve were finally selected which fell closest to the mean. Six of the TLDs were randomly selected and placed in a Rando female phantom in a position corresponding to the lens of the eye-3 in the left and 3 in the right eye. A standard pantomogram was taken of the phantom using an Orthophos machine. The TLDs were then replaced by another two groups of 3 in the same positions in the phantom and a lateral cephalogram taken on the same machine. The TLDs were read in the Toledo reader. Six of the 12 TLDs were then randomly selected for re-use. Three were placed in the phantom in the region of the thyroid and a pantomogram again taken. The procedure was repeated for a cephalogram and the TLDs again read. In all cases the readings of each group of 3 TLDs did not vary by more than 10% on either side of the mean readings. The TLD readings were then converted by means of a conversion factor to actual dose measurements. The doses to left and right eyes and to the thyroid were respectively found to be 0,0151, 0,0222 & 0,0896 mSv for the pantomogram and 0,0351, 0,0183 & 0,0177 mSv for the cephalogram--an almost insignificant dose in terms of the "background equivalent" concept. PMID:12705098

Buch, B; Fensham, R

2003-02-01

213

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

SciTech Connect

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

Liu, J.C. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Sims, C.S. (Oak Ridge National Lab., TN (USA))

1991-02-01

214

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

215

Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV  

SciTech Connect

The personal dose equivalent, H{sub p}(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity Effective Dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk where personal dosemeters are usually worn and in this instance a suitable approximation is a 30 cm X 30 cm X 15 cm slab-type phantom. For this condition the personal dose equivalent is denoted as H{sub p,slab}(d) and the depths, d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several MeV, however, data to higher energies are limited. In this work conversion coefficients up to 1 GeV have been calculated for H{sub p,slab}(10) and H{sub p,slab}(3) using both the kerma approximation and by tracking secondary charged particles. For H{sub p}(0.07) the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H{sub p,slab}(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared to the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance.

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

2010-09-27

216

Laser Stimulated Thermoluminescence  

NASA Astrophysics Data System (ADS)

Techniques for localized heating of semi-infinite single-layer and two-layer structures are investigated theoretically and experimentally, motivated by applications in thermoluminescence (TL) dosimetry of ionizing radiation. The heat-conduction equations are solved by the Green's function technique to obtain the transient temperature distribution caused by exposure to laser beams of Gaussian and uniform circular intensity profiles. It is shown that the spatio-temporal temperature response is readily monitored by the TL response that results when layer configuration contains a thermoluminescent phosphor. The experiments for the verification of the developed theory are performed with two specially constructed TL detection systems, one featuring a laser beam of Gaussian profile and the other a uniform circular laser beam. Measurements of the thermoluminescent emission from a number of different TL systems are performed and compared with computed responses on the basis of simple electron kinetics. We experiment exclusively with the commercial TL phosphor LiF:Mg,Ti(TLD-100, Harshaw), the most widely used material in thermoluminescence dosimetry. We study in detail localized Gaussian beam heating of it in the form of 0.9 mm thick slabs, self-supporting firms of fine-grain powder in a polyimide (Kapton) matrix, and on substrates of LiF single crystals or borosilicate glass. Thermoluminescent layers on glass substrates have been heated with Gaussian and uniform circular intensity profiles in two different modes: the laser beam impinges onto (a) the phosphor layer, and (b) the glass substrate. It is demonstrated that the optical and thermal behavior of the dosimeters can be determined by these methods and that, furthermore, the thermoluminescence response of a given configuration can be simulated as a function of a number of experimental parameters such as laser power, beam size, substrate and TL-layer thicknesses, and configuration of the dosimeters. In addition, we have investigated the dependence of the luminous efficiency (normalized thermoluminescence yield) and peak heights on heating rates in the range from 4 K/s to 5500 K/s. The efficiency values obtained are then included in the comparison of experimental and theoretical TL responses curves for various laser powers.

Abtahi, Abdollah

217

Thermoluminescence responses of terbium-doped magnesium orthosilicate with different synthesis conditions.  

PubMed

Numerous materials have been proposed for thermoluminescence dosemeter, and the example of highest sensitivity is cited as magnesium orthosilicate doped with terbium (Mg2SiO4:Tb). Nevertheless, the material is currently not commercially attractive because the sensitivity varies greatly with synthesis techniques. This is a multi-parameter problem, and the current work explores some of the conditions required to consistently enhance the response. These new results show that to get a high TL response, Mg2SiO4:Tb should be prepared at a high temperature of at least 1500°C, for sintering times of several hours. In the current example, the optimum time was 6 h. Signals also vary with the terbium activator concentration, and good responses were achieved with a concentration of Tb at 5 wt %. Overall, this suggests that with careful preparation, the potentially high dosimetry performance might be exploited. The inherent problem of concentration quenching is considered, and the potential benefits of processing the powder with pulse laser annealing are reviewed in the light of successful luminescence and laser studies for rare-earth-doped laser materials. PMID:24101655

Wang, Y; Jiang, Y; Chu, X; Xu, J; Townsend, P D

2014-03-01

218

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

219

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

220

Uncertainties in workplace external dosimetry--an analytical approach.  

PubMed

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

Ambrosi, P

2006-01-01

221

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

222

Evaluation of patient exposure in computerised tomogram in Poland.  

PubMed

The increasing number of computerised tomography (CT) procedures performed in Poland in recent years has resulted in a growing contribution of these examinations to the whole exposure of the population to ionising radiation from medical sources. (The number of CT examinations in Poland was 170,000 in 1995 and 460,000 in 1999.) An evaluation is presented of doses to patients in CT examinations performed with different types of CT unit. To evaluate the exposure to patients dose linear product (DLP) was measured using a NOMEX dosemeter with a pencil chamber (PTW, Frieburg) and the cylindrical PMMA phantoms 'head' and 'body'. CTDI values were evaluated according to current methodology as described in European Guidelines (EUR 16262). The measurements were performed for seven types of CT unit made by different companies. The CTDI values were also compared to reference levels recommended by IAEA. In conclusion it was found that the value of collective effective dose (2200 man.Sv), has increased in Poland nearly 4 times in comparison to 1995, whereas the number of CT examinations increased nearly 3 times in this period. For most of the 'controlled' CT scanners the values of CTDI in head procedures are near to or higher than the IAEA Reference Level (50 mGy); this can result from the protocols, which are chosen without a dose analysis. PMID:12120672

Staniszewska, M A

2002-01-01

223

Monte carlo study of MOSFET packaging, optimised for improved energy response: single MOSFET filtration.  

PubMed

Monte Carlo simulations of the energy response of a conventionally packaged single metal-oxide field effect transistors (MOSFET) detector were performed with the goal of improving MOSFET energy dependence for personal accident or military dosimetry. The MOSFET detector packaging was optimised. Two different 'drop-in' design packages for a single MOSFET detector were modelled and optimised using the GEANT4 Monte Carlo toolkit. Absorbed photon dose simulations of the MOSFET dosemeter placed in free-air response, corresponding to the absorbed doses at depths of 0.07 mm (D(w)(0.07)) and 10 mm (D(w)(10)) in a water equivalent phantom of size 30 x 30 x 30 cm(3) for photon energies of 0.015-2 MeV were performed. Energy dependence was reduced to within + or - 60 % for photon energies 0.06-2 MeV for both D(w)(0.07) and D(w)(10). Variations in the response for photon energies of 15-60 keV were 200 and 330 % for D(w)(0.07) and D(w)(10), respectively. The obtained energy dependence was reduced compared with that for conventionally packaged MOSFET detectors, which usually exhibit a 500-700 % over-response when used in free-air geometry. PMID:20460400

Othman, M A R; Cutajar, D L; Hardcastle, N; Guatelli, S; Rosenfeld, A B

2010-09-01

224

Comparison of entrance surface doses of some X ray examinations with CEC reference doses.  

PubMed

Entrance surface dose (ESD) measurements have been carried out in Nigeria as part of the ongoing dose reduction programme. Thermoluminescence dosemeters (TLD) were used to measure skin entrance doses for four common radiographic views in three hospitals. The mean ESD for the PA chest examination in all the participating hospitals was in the range 0.12 - 4.46 mGy. The mean ESD for the AP skull. PA skull and LAT skull were 8.55, 5.17 and 6.97 mGy respectively. The mean ESD values are greater than the CEC reference doses, except for rooms 1 and 2 in UCH where the entrance surface doses for PA chest examination are below the CEC reference dose. The QA test results show non-compliance of the accuracy of tube voltage with acceptance limit in three rooms. The timer accuracy is also not within the acceptance limit in two rooms. The reproducibility of both the kVp and timer in all the rooms is good. PMID:11930883

Ogunseyinde, A O; Adeniran, S A M; Obed, R I; Akinlade, B I; Ogundare, F O

2002-01-01

225

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

226

State-of-the-art dosimetric methods for internal and external exposures: conclusions of a EURADOS action.  

PubMed

In radiation protection dosimetry the quantity of interest is the effective dose (E); the dose limit to an adult worker applies to the sum of the relevant doses from external exposures and the relevant committed effective doses from intakes of radionuclides, during the same period of time. A EURADOS study was carried out to investigate how the results from personal dosemeters for external radiation, from workplace monitoring and from monitoring of internal exposures can be combined into a consistent system of individual monitoring. The integration of dosimetric methods and data for external and internal radiation require the complete characterisation of the occupational exposure present at the workplace, and the availability of adequate equipment and tools for the assessment of effective dose. To evaluate the capability of services to accomplish this approach, a European Dosimetry Network has been established among 28 European countries through the respective contact-persons and their dosimetric facilities which collaborated with EURADOS providing relevant data about performance and legal aspects. The information collected was presented as a monograph in Radiation Protection Dosimetry in 2004. The more relevant conclusions of this study are presented here. PMID:17213216

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

2007-01-01

227

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

PubMed

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

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

2004-01-01

228

Novel shielding materials for space and air travel.  

PubMed

The reduction of dose onboard spacecraft and aircraft by appropriate shielding measures plays an essential role in the future development of space exploration and air travel. The design of novel shielding strategies and materials may involve hydrogenous composites, as it is well known that liquid hydrogen is most effective in attenuating charged particle radiation. As precursor for a later flight experiment, the shielding properties of newly developed hydrogen-rich polymers and rare earth-doped high-density rubber were tested in various ground-based neutron and heavy ion fields and compared with aluminium and polyethylene as reference materials. Absorbed dose, average linear energy transfer and gamma-equivalent neutron absorbed dose were determined by means of LiF:Mg,Ti thermoluminescence dosemeters and CR-39 plastic nuclear track detectors. First results for samples of equal aerial density indicate that selected hydrogen-rich plastics and rare-earth-doped rubber may be more effective in attenuating cosmic rays by up to 10% compared with conventional aluminium shielding. The appropriate adaptation of shielding thicknesses may thus allow reducing the biologically relevant dose. Owing to the lower density of the plastic composites, mass savings shall result in a significant reduction of launch costs. The experiment was flown as part of the European Space Agency's Biopan-5 mission in May 2005. PMID:16717109

Vana, N; Hajek, M; Berger, T; Fugger, M; Hofmann, P

2006-01-01

229

Experimental qualification of a code for optimizing gamma irradiation facilities  

NASA Astrophysics Data System (ADS)

Dose computation codes are a prerequisite for the design of gamma irradiation facilities. Code quality is a basic factor in the achievement of sound economic and technical performance by the facility. This paper covers the validation of a code by reference dosimetry experiments. Developed by the "Société Générale pour les Techniques Nouvelles" (SGN), a supplier of irradiation facilities and member of the CEA Group, the code is currently used by that company. (ERHART, KERARON, 1986) Experimental data were obtained under conditions representative of those prevailing in the gamma irradiation of foodstuffs. Irradiation was performed in POSEIDON, a Cobalt 60 cell of ORIS-I. Several Cobalt 60 rods of known activity are arranged in a planar array typical of industrial irradiation facilities. Pallet density is uniform, ranging from 0 (air) to 0.6. Reference dosimetry measurements were performed by the "Laboratoire de Métrologie des Rayonnements Ionisants" (LMRI) of the "Bureau National de Métrologie" (BNM). The procedure is based on the positioning of more than 300 ESR/alanine dosemeters throughout the various target volumes used. The reference quantity was the absorbed dose in water. The code was validated by a comparison of experimental and computed data. It has proved to be an effective tool for the design of facilities meeting the specific requirements applicable to foodstuff irradiation, which are frequently found difficult to meet.

Mosse, D. C.; Leizier, J. J. M.; Keraron, Y.; Lallemant, T. F.; Perdriau, P. D. M.

230

Micronucleus induction in peripheral blood lymphocytes of patients under radiotherapy treatment for cervical cancer or Hodgkin's disease.  

PubMed

The genetic damage present in peripheral blood lymphocytes of patients treated with fractionated partial-body radiation therapy for cervical cancer or Hodgkin's disease was followed during treatment by means of the cytokinesis-block micronucleus assay. For each patient a dose-response relationship with respect to the number of micronuclei after in vitro irradiation of blood samples pretreatment was also determined. Comparing the individual in vivo-in vitro data, the micronucleus yields after the equivalent whole-body dose during radiotherapy were found to differ substantially from the in vitro dose-response. Contrary to the linear-quadratic dose dependence after in vitro irradiation the initial increase in the micronucleus yield during radiotherapy levelled off at elevated doses. The observed differences cannot be attributed only to the effects of interphase death and the partial irradiation of the lymphocyte pool. The correlation between the micronucleus yield and the equivalent whole-body dose for values up to 2 Gy, observed for the pooled data of the first part of the radiotherapy treatment, demonstrates the suitability of the cytokinesis-block micronucleus assay as a biological dosemeter after accidents involving partial-body irradiation. PMID:7775828

Thierens, H; Vral, A; Van Eijkeren, M; Speleman, F; De Ridder, L

1995-05-01

231

Three-dimensional radiation dose measurements with Ferrous Benzoic Acid Xylenol Orange in Gelatin gel and optical absorption tomography  

NASA Astrophysics Data System (ADS)

The optical characteristics of a Ferrous Benzoic Acid Xylenol Orange in Gelatin (FBXG) gel have been studied over the wavelength range 300-700 nm as a function of radiation dose. The unirradiated gel exhibits a strong absorption peak at 440 nm; with increasing dose this peak starts to reduce in intensity while a new broad peak centred at 585 nm begins to appear. Using 60Co gamma rays the absorption coefficients for these two peaks were found to vary linearly with dose up to at least 30 Gy with slopes of -0.028 cm-1 Gy-1 (440 nm) and 0.069 cm-1 Gy-1 (585 nm). The pre- and post-irradiation stability was studied and absorbance changes of less than 1% per hour were observed over periods of a few days. The NMR response of FBXG gels was found to be marginally reduced compared to the standard Fricke dosemeter in gel form and the NMR technique is much less sensitive than the optical readout method. Tissue equivalent phantoms with dimensions of several centimetres can be constructed of FBXG gel and Optical Absorption Tomography (OAT) used to measure the three-dimensional dose distribution within them after exposure to radiation beams. The OAT technique is a much simpler and cheaper method of readout compared with Magnetic Resonance Imaging (MRI).

Bero, M. A.; Gilboy, W. B.; Glover, P. M.; Keddie, J. L.

1999-02-01

232

Thyroid exposure to scattered radiation and associated second cancer risk from paediatric radiotherapy for extracranial tumours.  

PubMed

This study was conducted to estimate the scattered thyroid dose and relevant second cancer risk from radiotherapy for extracranial tumours during childhood.  Anteroposeterior and posteronaterior field irradiations employed during the treatment of Hodgkin's disease, neuroblastoma and Wilms' tumour were simulated on two humanoid phantoms representing 5- and 10-y-old patients. Measurements were performed using thermoluminescent dosemeters. Practical thyroid lead shields with thicknesses of 2-10 mm were placed in the phantoms' neck region. The lifetime risk for cancer induction was assessed using sex- and age-specific risk factors. Thyroid dose per monitor unit varied from 28.1 to 492.4 ?Gy by the primary irradiation site and patient's age. The 10-mm-thick lead shield led to a dose reduction up to 28.9 %. For typical prescribed tumour doses, the total risks for thyroid cancer development after radiotherapy of 5- and 10-y-old male patients were 0.05-0.99  and 0.03-0.48 %, respectively. The corresponding risks for females increased to 0.29-5.51 and 0.17-2.94 %. PMID:22504308

Mazonakis, Michalis; Kourinou, Kalliopi; Lyraraki, Efrossini; Varveris, Haralambos; Damilakis, John

2012-12-01

233

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.

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

2013-01-01

234

Indoor (222)Rn and (220)Rn concentrations and doses in Bangalore, India.  

PubMed

(222)Rn and (220)Rn levels have been measured using passive detector technique by employing time integrated solid-state nuclear track detector-based dosemeters in various types of houses at 10 different locations in and around Bangalore Metropolitan, India. The measured geometric mean concentration values of (222)Rn and (220)Rn levels in 200 dwellings of different types of construction were found to be 32.2±1.6 and 21.4±1.0 Bq m(-3), respectively. The dose rate received by the population of Bangalore ranged between 0.2 and 3.5 mSv y(-1) with an average and the geometric mean of 1.14±0.05 and 1.06 mSv y(-1), respectively. Overall, the result does not show much significant radiological risk for the inhabitants and the (222)Rn levels are well within the limits of global average concentration of 40 Bq m(-3). However, the (220)Rn levels observed were found to be higher than the global average of 10 Bq m(-3). PMID:22375038

Sathish, L A; Nagaraja, K; Ramachandran, T V

2012-08-01

235

Preliminary indoor thoron measurements in high radiation background area of southeastern coastal Orissa, India.  

PubMed

This paper presents the preliminary results of radon and thoron measurements in the houses of Chhatrapur area of southeastern coast of Orissa, India. This area is one of the high radiation background radiation areas in India, which consists of monazite sand as the source of thoron. Both active and passive methods were employed for the measurements. Radon and thoron concentrations were measured in the houses of Chhatrapur area using twin cup radon dosemeters, RAD7 and radon-thoron discriminative detector (Raduet). Thoron progeny concentration was also measured in the houses using deposition rate measurements. Radon and thoron concentrations in the houses of study area were found to vary from 8 to 47 Bq m(-3) and the below detection level to 77 Bq m(-3), respectively. While thoron progeny concentration in these houses ranges between 0.17 and 4.24 Bq m(-3), preliminary investigation shows that the thoron concentration is higher than radon concentration in the houses of the study area. The thoron progeny concentration was found to be comparatively higher, which forms a base for further study in the area. The comparison between the results of various techniques is presented in this paper. PMID:20833682

Ramola, R C; Prasad, G; Gusain, G S; Rautela, B S; Choubey, V M; Sagar, D Vidya; Tokonami, S; Sorimachi, A; Sahoo, S K; Janik, M; Ishikawa, T

2010-10-01

236

Survey of radon and thoron in homes of Indian Himalaya.  

PubMed

Measurements of radon, thoron and their progeny were carried out in some houses from Garhwal and Kumaun Himalayas of India using a LR-115 plastic track detector. The measurements were made in various residential houses of the area at a height of 2.5 m above the ground level using a twin chamber radon dosemeter, which can record the values of radon, thoron and their progeny separately. The concentrations of radon and thoron in these homes were found to vary from 11 to 191 and 1 to 156 Bq m(-3), respectively. The equilibrium factor between radon and progeny varies from 0.02 to 0.90, with an average of 0.26 for the region. The resulting dose rate due to radon, thoron and their decay products was found to vary from 0.02 to 0.84 ?Sv h(-1) with an arithmetic mean of 0.27 ?Sv h(-1). A detailed analysis of the distribution of radon, thoron and their decay products inside a house is also reported. The observed dose rates due to radon, thoron and progeny were found somewhat higher but well below the international recommendations. PMID:21486831

Ramola, Rakesh Chand

2011-07-01

237

An investigation into the effect of protective devices on the dose to radiosensitive organs in the head and neck.  

PubMed

A series of experiments were performed to determine the dose reduction afforded to radiosensitive organs in the head and neck by various protective devices. These included spectacles with plastic, standard glass, photochromic and lead-glass lenses, a thyroid collar and a lead-acrylic face mask. The measurements were performed using an anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters, in conditions realistic of clinical practice. Irradiations were performed using scattered radiation produced by a pelvic phantom, for X-ray beams generated at 80 kVp and 110 KVp. It was found that the reduction in dose to the lens of the eye ranged between 0% and 97%, whilst the dose to the thyroid and oesophagus was reduced by between 76% and 97%, and was dependent on the protective device and tube potential employed. A reduction in brain dose of up to 81% was also measured, for the lead-acrylic face mask. Also presented is the ratio of organ dose to dose to the bridge of the nose for thyroid, oesophagus, brain and sinuses, as measured for the case of no head or neck protection. PMID:1393418

Marshall, N W; Faulkner, K; Clarke, P

1992-09-01

238

Use of lead shields for radiation protection of superficial organs in patients undergoing head CT examinations.  

PubMed

Head computed tomography examinations are often accompanied with unnecessary irradiation of superficial organs that are rarely the main target for the investigation. The aim of this work is to demonstrate that lead shields could be effectively used to protect superficial organs without compromising image quality where superficial organ itself is not a target and that the irradiation of the superficial organ is unavoidable. The objective was achieved by first assessing the image quality using phantom measurements made with and without lead shielding in order to determine optimal shielding thickness for patient applications. The entrance surface doses (ESDs) to superficial organs of sixty patients were measured using LiF-thermoluminescent dosemeters without, with one layer, or with two layers of lead shields. Phantom studies demonstrated that the use of modified lead shields of up to 0.25 mm thickness could be used without significant effect on the image quality for central and posterior regions. In these studies, lead shields of 0.25 mm thickness reduce the ESDs to the lens of the eyes and thyroid by 44 and 51%, respectively. The image quality reduction by eye shields was significant to the anterior (i.e. orbital) region but marginal to the central and posterior regions (cerebrum). In view of the above, the use of modified lead shields could reduce the dose to the superficial organs considerably without significantly compromising image quality. PMID:18375945

Ngaile, J E; Uiso, C B S; Msaki, P; Kazema, R

2008-01-01

239

Organ and effective doses from verification techniques in image-guided radiotherapy.  

PubMed

The purpose of this work was an evaluation of organ doses and effective doses from three verification techniques in Image-Guided Radiotherapy: from kilovoltage (kV) cone beam computed tomography (CBCT) scans, from two orthogonal kV images and from two orthogonal megavoltage (MV) images for two different treatment sites: pelvis and head and neck (H&N). For comparison reasons, organ doses and effective doses from prostate and H&N radiotherapy were also evaluated. Measurements of organ doses were performed in a male anthropomorphic Rando phantom by means of thermoluminescent dosemeters. In this investigation, measured organ doses from one CBCT scan, from two MV images and from two kV images of pelvis represent typically 1-6, 1-10 and 0.05-1 %, respectively, of organ doses resulting from one fraction of prostate radiotherapy. The maximum effective doses from CBCT scans, kV images and MV images of pelvis are 5.6, 0.8 and 11.9 mSv, respectively. PMID:21816726

Dufek, V; Horakova, I; Novak, L

2011-09-01

240

Measurement of dose in panoramic dental radiology.  

PubMed

The National Radiological Protection Board (NRPB) has recommended the introduction of dose-width product (DWP) for the measurement of patient dose in panoramic dental radiology and has proposed a reference level of 65 mGy mm for adult exposures. This paper describes a method for measuring DWP and dose-area product (DAP) using thermoluminescent dosemeters (TLDs). The technique was used on 16 sets with a range of exposure settings. The mean value of DWP was 14% higher than the mean value reported from a survey by the NRPB. This difference is most likely to be caused by systematic variations due to measurement method. The average DAP for a standard adult examination was shown to be 11.3 cGy cm2. Data are presented so that the DAP can be derived from the exposure factors (tube current and operating potential) and beam area. Based on published data for effective dose, it is estimated that the DAP to effective dose conversion factor is approximately 0.06 mSv(Gy cm2)-1. The average DAP value (11.3 cGy cm2) can be compared with the average value for intraoral radiography (9.3 cGy cm2) based on the NRPB survey of entrance surface doses assuming 6 cm circular collimation. PMID:11064656

Williams, J R; Montgomery, A

2000-09-01

241

Thermoluminescence properties of Li2CO3-K2CO3-H3BO3glass system co-doped with CuO and MgO.  

PubMed

The thermoluminescent properties of boric glass modified with lithium and potassium carbonates (LKB) and co-doped with CuO and MgO are reported for the first time. Two techniques are applied to investigate the effect of dopants and co-dopants on the thermal stimulation properties of LKB. The induced TL glow curves of a CuO-doped sample are found to be at 220°C with a single peak. An enhancement of about three times is shown with the increment of 0.1 mol % MgO as a co-dopant impurity. This enhancement may contribute to the ability of magnesium to create extra electron traps and consequently the energy transfer to monovalent Cu(+) ions. LKB:Cu,Mg is low Z material (Zeff=8.55), and observed 15 times less sensitive than LiF: Mg, Ti (TLD-100). The proposed dosemeter showed good linearity in TL dose-response, low fading and excellent reproducibility with a simple glow curve, and thus, can be used in the radiation dosimetry. PMID:23193136

Alajerami, Yasser Saleh Mustafa; Hashim, Suhairul; Ramli, Ahmad Termizi; Saleh, Muneer Aziz; Kadni, Taiman

2013-06-01

242

Low-dose radiation hyper-radiosensitivity in multicellular tumour spheroids  

PubMed Central

Objective We propose and study a new model aimed at describing the low-dose hyper-radiosensitivity phenomenon appearing in the survival curves of different cell lines. Methods The model uses the induced repair assumption, considering that the critical dose at which this mechanism begins to act varies from cell to cell in a given population. The model proposed is compared with the linear-quadratic model and the modified linear-quadratic model, which is commonly used in literature and in which the induced repair is taken into account in a heuristic way. The survival curve for the MCF-7 line of human breast cancer is measured at low absorbed doses and the uncertainties in these doses are estimated using thermoluminiscent dosemeters. Results It is shown that these multicellular spheroids present low-dose hyper-radiosensitivity. The new model permits an accurate description of the data of two human cell lines (previously published) and of the multicellular spheroids of the MCF-7 line here measured. Conclusion The model shows enough flexibility to account for data with very different characteristics and considers in a faithful way the hypothesis of the repair induction.

Guirado, D; Aranda, M; Ortiz, M; Mesa, J A; Zamora, L I; Amaya, E; Villalobos, M; Lallena, A M

2012-01-01

243

Radiation measurements around X-ray cabinet systems.  

PubMed

Security personnel who operate X-ray units for the control of hand luggage and personal items at airports are generally not under dosimetric surveillance. A significant increase in the number of inspected items per passenger, due to rigorous air traffic security measures, raises a question of extended exposure of these workers to scattered X-ray radiation. A new approach to investigating directions of breaches of scattered X-ray radiation in the area near to an X-ray cabinet system, which is based on using active electronic dosemeters is presented. Influence of the increase in the number of inspected items in time on the dose rate is described. Time-dependent dose rates have showed a very good correlation with passengers undergoing security control prior to boarding an airplane. Measurements confirmed that an increase in the dose rate, coinciding with rush hours, was caused by scattered radiation passing through incompletely closed lead curtains. It is found that the doses at the entrance to the inspection tunnel are 50% higher than those at the exit, which is a consequence of inherent operational characteristics of X-ray cabinet systems. PMID:22302108

Suric Mihic, M; Vucic, Z; Prlic, I; Lulic, I; Mestrovic, T

2012-07-01

244

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

245

On-board TLD measurements on MIR and ISS.  

PubMed

This paper presents results from dosimetric measurements made aboard the Mir space station and the International Space Station (ISS) using the Pille portable thermoluminescent dosemeter (TLD) system. This paper includes the dosimetry mapping and automatic readout (trapped and untrapped components) results from Mir and ISS. The mean dose rate in 2001-2003 was 7 microGy h(-1). Using the hourly measuring period in automatic mode, doses from both galactic (independent of South Atlantic Anomaly--SAA) and SAA components were determined during Euromir'95 experiment. The mean total dose rate was 12.5 microGy h(-1), while the SAA contribution was 6.2 microGy h(-1). A similar measurement was performed on ISS in 2001 and in 2003. Both the manual and automatic measurements show a significant decrease in dose rate in 2001 in comparison to 1995-1997 due to the change in solar activity. For determination of the high linear energy transfer contribution from the radiation field during the ISS mapping experiment, three CR-39 plastic nuclear track detectors (PNTDs) were co-located with each TL detector. Analysis of the combined TLD and PNTD measurements showed a typical mean TLD efficiency of 84%, a dose contribution <10 keV microm(-1) of 17%, and an average quality factor of 1.95. PMID:16709717

Deme, S; Apáthy, I; Pázmándi, T; Benton, E R; Reitz, G; Akatov, Y

2006-01-01

246

Estimation of the risk of secondary cancer in the thyroid gland and the breast outside the treated volume in patients undergoing brain, mediastinum and breast radiotherapy.  

PubMed

The purpose of this study was to measure the peripheral dose which is the absorbed dose in organs located outside the treatment volume such as the thyroid gland and the breast in patients undergoing radiotherapy, utilising the MOSFET dosemeters, as well as to estimate the probability of secondary cancer. The thyroid gland doses, expressed as a percentage of the prescribed dose (%TD), were measured to be 2.0±0.3 %, in whole brain irradiation, 10.0±8.0 % in mediastinum treatment and 8.0±2.0 and 2.0±0.8 % in breast treatment, with and without the supraclavicular irradiation, respectively, with a corresponding risk of 0.2, 2.0, 1.0 and 0.3 %. The dose to the breast was 7.0±2.0 %, in the mediastinum treatment, and 4.0±1.0 and 2.0±0.8 %, in the breast treatment, with and without supraclavicular irradiation, respectively, with a corresponding risk of 4.0, 2.0 and 1.0 %. Although the results indicate that the risk is not negligible, its significance should be considered in conjunction with the existing pathology and age of the patients. PMID:22923288

Vlachopoulou, Vassiliki; Malatara, Georgia; Delis, Harry; Kardamakis, Dimitrios; Panayiotakis, George

2013-04-01

247

Calculation of personal dose equivalent for positron-emitting radionuclides using Monte Carlo code EGS5.  

PubMed

The conversion coefficients, H'(d,?)/?, for monoenergetic positrons and positron-emitting radionuclides were calculated by using the user code UCICRPM of the Monte Carlo code EGS5 to estimate the radiation dose for medical staff involved in positron emission tomography examinations. From these coefficients, the dose equivalent rates per unit activity at 0.07 and 10 mm depths in a soft tissue for a straight-line source of 2-deoxy-2-[(18)F]fluoro-d-glucose ((18)F-FDG) were calculated by using the developed user code UCF18DOSE. The dose equivalent rates per unit activity at 0.07 and 10 mm depths were measured by using a personal dosemeter (DOSE(3)) under the same conditions as those considered in the calculation. The calculated dose equivalent rates per unit activity at 0.07 and 10 mm depths were 0.116 and 0.0352 pSv min(-1) Bq(-1), respectively, at 20 cm from the (18)F-FDG injection tube. PMID:21498852

Kato, T; Aoki, K; Yokoyama, S; Ejiri, K; Minami, K; Yashima, H; Taniguchi, A; Nakamura, T; Hirayama, H

2011-07-01

248

A parametric model to describe neutron spectra around high-energy electron accelerators and its application in neutron spectrometry with Bonner Spheres  

NASA Astrophysics Data System (ADS)

Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.

Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo

2010-03-01

249

Optimising radiographic bitewing examination to adult and juvenile patients through the use of anthropomorphic phantoms.  

PubMed

Four anthropomorphic phantoms (an adult male, an adult female, a 10-y-old child and a 5-y-old child) were exposed to bitewing radiographs at film and digital settings using both rectangular and round collimation. Optically stimulated dosemeters were used. For children, average organ doses were <40 µGy and the organs with the highest doses were the salivary glands, parotid, oral mucosa, skin and extrathoracic airway. For adults, average organ doses were <200 µGy. Highest adult doses were to the salivary glands, oral mucosa and skin. Effective doses ranged from 1.5 to 1.8 µSv for children and from 2.6 to 3.6 µSv for adults when optimised technique factors were employed, including digital receptors, rectangular collimation, size-appropriate exposure times and proper clinical judgment. Optimised doses were a fraction of the natural daily background exposure. Therefore, predictions of hypothetical cancer incidence or detriment in patient populations exposed to such low doses are highly speculative and should be discouraged. PMID:23918744

Dauer, Lawrence T; Branets, Iryna; Stabulas-Savage, Jeanine; Quinn, Brian; Miodownik, Daniel; Dauer, Zachary L; Colosi, Dan; Hershkowitz, David; Goren, Arthur

2014-01-01

250

Radiation doses to the population in The Netherlands, due to external natural sources.  

PubMed

An estimate has been made of gamma doses to the population in the Netherlands, caused by natural radiation sources encountered in the environment. Data are given, derived from two independent types of measurement: Exposure/dose rate measurements in the living environment (private houses as well as workplaces), using a high pressure ionization chamber and thermoluminescent dosemeters (TLD) respectively and Individual monitoring, using TLD. The study included some 750 individuals, 400 houses and 275 workplaces. The participants were selected and divided into two groups on the basis of their location in areas of relatively high and low terrestrial radiation level respectively. Distinction was made between three categories of individuals with respect to their patterns of life. An estimate was made of the influence of the terrestrial component of the natural background and of some typical building materials on the indoor radiation level. An average indoor exposure rate of 9.5 muR . h-1 and a dose rate of 95 nGy . h-1 for individuals were found, both with a standard deviation of 15-20%. PMID:4081746

Julius, H W; van Dongen, R

1985-10-01

251

Low-energy x-ray dosimetry studies (6 to 16 keV) at SSRL beamline 1-5  

NASA Astrophysics Data System (ADS)

Synchrotron radiation facilities provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory (SSRL) are described. Polish lithium fluoride thermoluminescent dosemeters (TLDs), MTS-N(LiF:Mg, Ti- 0.4 mm thick), MCP-N (LiF:Mg, Cu, P - 0.4 mm thick) were exposed free in air to monochromatic x-rays (6-16 keV). These exposures were monitored with an SSRL ionization chamber. The responses (counts/Gy) of MTS-N and MCP-N were generally found to increase with increasing energy. The response at 16 keV is about 3 and 4 times higher than the response at 6 keV for MTS-N and MCP-N, respectively. Irradiation at 6 keV indicates a fairly linear dose response for both type of TLDs over a dose range of 0.01 to 0.4 Gy. In addition there appears to be no significant difference in responses between irradiating the TLDs from the front and the back sides. The energy response of the PTW ionization chamber type 23342 relative to the SSRL ionization chamber is within +/-4.5% between 6 and 16 keV. Both the TLDs and the PTW ionization chamber can also be used for beam dosimetry.

Ipe, N. E.; Chatterji, S.; Fassň, A.; Kase, K. R.; Seefred, R.; Olko, P.; Bilski, P.; Soares, C.

1997-07-01

252

Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom  

NASA Astrophysics Data System (ADS)

High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mm×300 mm×300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cross-sectional area of 100 mm 2 at a depth of 150 mm of the PMMA phantom, was measured as 3.3×10 6 mGy h -1W -1 for 7-GeV bremsstrahlung spectrum.

Job, P. K.; Pisharody, M.; Semones, E.

1999-12-01

253

Reliability in individual monitoring service.  

PubMed

As a laboratory certified to ISO 9001:2008 and accredited to ISO/IEC 17025, the Secondary Standard Dosimetry Laboratory (SSDL)-Nuclear Malaysia has incorporated an overall comprehensive system for technical and quality management in promoting a reliable individual monitoring service (IMS). Faster identification and resolution of issues regarding dosemeter preparation and issuing of reports, personnel enhancement, improved customer satisfaction and overall efficiency of laboratory activities are all results of the implementation of an effective quality system. Review of these measures and responses to observed trends provide continuous improvement of the system. By having these mechanisms, reliability of the IMS can be assured in the promotion of safe behaviour at all levels of the workforce utilising ionising radiation facilities. Upgradation of in the reporting program through a web-based e-SSDL marks a major improvement in Nuclear Malaysia's IMS reliability on the whole. The system is a vital step in providing a user friendly and effective occupational exposure evaluation program in the country. It provides a higher level of confidence in the results generated for occupational dose monitoring of the IMS, thus, enhances the status of the radiation protection framework of the country. PMID:21147789

Mod Ali, N

2011-03-01

254

Criticality accident dosimetry systems: an international intercomparison at the SILENE reactor in 2002.  

PubMed

In criticality accident dosimetry and more generally for high dose measurements, special techniques are used to measure separately the gamma ray and neutron components of the dose. To improve these techniques and to check their dosimetry systems (physical and/or biological), a total of 60 laboratories from 29 countries (America, Europe, Asia) participated in an international intercomparaison, which took place in France from 9 to 21 June 2002, at the SILENE reactor in Valduc and at a pure gamma source in Fontenay-aux-Roses. This intercomparison was jointly organised by the IRSN and the CEA with the help of the NEA/OCDE and was partly supported by the European Communities. This paper describes the aim of this intercomparison, the techniques used by the participants and the two radiation sources and their characteristics. The experimental arrangements of the dosemeters for the irradiations in free air or on phantoms are given. Then the dosimetric quantities measured and reported by the participants are summarised, analysed and compared with the reference values. The present paper concerns only the physical dosimetry and essentially experiments performed on the SILENE facility. The results obtained with the biological dosimetry are published in two other papers of this issue. PMID:15353686

Médioni, R; Asselineau, B; Verrey, B; Trompier, F; Itié, C; Texier, C; Muller, H; Pelcot, G; Clairand, I; Jacquet, X; Pochat, J L

2004-01-01

255

Photoneutron contamination from an 18 MV Saturne medical linear accelerator in the treatment room.  

PubMed

Dose escalation with high-energy X rays of medical linear accelerators (linacs) in radiotherapy offers several distinct advantages over the lower energy photons. However, owing to photoneutron reactions, interaction of high-energy photons (>8 MV) with various high-Z nuclei of the materials in the linac head components produces unavoidable neutrons. The aim of this study was to evaluate the photoneutron dose equivalent per unit therapeutic X-ray dose of 18 MV, GE Saturne 20 linac in the treatment room using Monte Carlo (MC) MCNP linac head full simulation as well as thermoluminescence dosemeter measurements. This machine is one of the old linac models manufactured by General Electric Company; however, it is widely used in the developing countries because of low cost and simple maintenance for radiotherapy applications. The results showed a significant photoneutron dose from Saturne 20 linac head components especially at distances near the linac head (<150 cm). Results of this work could be used in several applications, especially designing bunker and entrance door shielding against neutrons produced by photoneutron reactions in GE Saturne 20. However, a detailed cost optimisation for a specific room would require a dedicated calculation. PMID:23538892

Khosravi, Mostafa; Shahbazi-Gahrouei, Daryoush; Jabbari, Keyvan; Nasri-Nasrabadi, Mehdi; Baradaran-Ghahfarokhi, Milad; Siavashpour, Zahra; Gheisari, Ruhollah; Amiri, Behnam

2013-09-01

256

Fading in CaF/sub 2/(Tm/Dy) TL phosphors used in environmental radiation monitoring  

SciTech Connect

Thermoluminescence dosimetry technique is currently used for occupational dosimetry and monitoring of supervised areas in the medical and industrial use of ionizing radiation. Recently, the problems about the potential effects of low dose levels, as those due to natural radiation or in the proximity of nuclear facilities, has produced a continuing interest in the study of thermoluminescent dosemeters for the measurement of environmental exposure. Undoubtedly, TLDs offer a number of advantages over other devices available for these purposes: they are small, relatively inexpensive, stable integrating detectors, which can be used in large number, placed everywhere, and assembled in a variety of arrangements. The aim of this paper is to report the fading observed for two different kind of calcium fluoride submitted to different climate conditions over storage time. CaF/sub 2/ (Dy/Tm) have been chosen because of their high sensitivity which makes them very useful in environmental dosimetry. On the other hand, the lower limit of the absorbed dose for CaF/sub 2/ is about 10/sup -6/Gy while for LiF is about 5x10/sup -5/Gy. Because the environmental absorbed dose in Italy is about 7x10/sup -5/Gy/month it is evident the usefulness of CaF/sub 2/ with respect to LiF.

Bacci, C.; Draghi, V.; Furetta, C.; Rispoli, B.

1989-02-01

257

Characterization of the scattered radiation field around an x-ray tube  

NASA Astrophysics Data System (ADS)

To determine patient doses or doses to the medical staff, Monte Carlo calculations are frequently applied. In these kinds of calculations the x-ray tube is often simplified to make the calculations faster. The purpose of this study is to investigate the influence of simplifications in the Monte Carlo set-up of the x-ray tube on the observed differences between measurements and calculations in the scattered field. At a distance of 50 and 100 cm from the focal spot, air kerma calculations are done for different angles from -90° to 90° from the central beam axis in steps of 15° with the Monte Carlo software code MCNP-X. Different calculations were performed where each time a component of the simulated x-ray tube (collimator, filters, etc) or the environment (walls) is included. Scattered doses are also measured with thermoluminescent dosemeters. For the most simplified geometry of the x-ray tube, measurements are on average 70% larger than the calculated results. A much better agreement with the measurements is observed for more realistic calculations. The current work applies to a particular source in the SCK•CEN calibration laboratory; therefore the obtained results are representative and relevant for studies in calibration laboratories. As clinical sources have more shielding material and as in real imaging situations the scatter generated at the patient is much larger than the scatter leaking from the source, the results of this study have a limited impact on the wider field of clinical dosimetry.

Struelens, Lara; Kauwenberghs, Kim; Vanhavere, Filip

2011-05-01

258

Absorbed doses from computed tomography for dental implant surgery: comparison with conventional tomography.  

PubMed

Tomography is often needed prior to implant surgery to evaluate jaw bone dimensions. Computed tomography (CT) is advocated as an alternative. The purpose of this study was to measure the absorbed doses to radiosensitive organ in the head and neck region when CT is used. Measurements were made with extruded LiF thermoluminescent dosemeters within and on an anthropomorphic phantom examined with a Philips Tomoscan LX CT scanner. Axial scanning was performed for the maxilla and both frontal, perpendicular to the alveolus, and axial for the mandible. The highest absorbed doses were at the skin surface, 38 mGy with maxillary scans, and from axial and frontal scans of the mandible 35 mGy and 37 Gy, respectively. The parotid dose was 31 mGy from maxillary scans and in the mandible the submandibular gland dose was 27 mGy with axial scanning and 16 mGy with frontal. The eye lens received its highest dose (5.5 mGy) from frontal scans of the mandible. Although outside the scanning plane the pituitary and the thyroid glands received comparatively high absorbed doses of 0.6-4.0 mGy. All organ doses measured were considerably higher than those reported for conventional tomography. PMID:8508935

Ekestubbe, A; Thilander, A; Gröndahl, K; Gröndahl, H G

1993-02-01

259

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.

260

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

261

Organ doses from prostate radiotherapy and associated concomitant exposures.  

PubMed

In addition to the therapeutic exposure, a course of radiotherapy will involve the additional (concomitant) irradiation of the patient using CT, simulator or portal imaging systems, for localization of the target volume and subsequent verification of treatment delivery. The number of concomitant exposures is likely to increase as the developing technical capabilities for conformal, image-guided radiotherapy make target and critical organ definition an increasingly important aspect of radiotherapy. Estimation of doses and risks to critical organs in the body from all sources is thus necessary to provide the basis for adequate justification of the exposures as required by ICRP. In this paper, doses to selected organs and tissues for which ICRP have identified fatal cancer probabilities have been measured using a realistic anthropomorphic phantom loaded with thermoluminescent dosemeters and irradiated using a treatment protocol for radical radiotherapy of the prostate. Independently, doses to the same organs and tissues have been measured from concomitant CT and portal imaging exposures given for localization and verification purposes. Although negligible in comparison with the target dose, realistic numbers of concomitant exposures give a small but significant contribution to the total dose to most organs and tissues outside the target volume. Generally, this is in the range 5-10% of the total organ dose, but can be as high as 20% for bone surfaces. These data may be used to estimate concomitant doses from any combination of CT and portal imaging and may help in the justification process, especially when additional verification exposures may be required during treatment. PMID:16714751

Harrison, R M; Wilkinson, M; Shemilt, A; Rawlings, D J; Moore, M; Lecomber, A R

2006-06-01

262

Replacement tissue-equivalent proportional counter for the International Space Station.  

PubMed

The tissue-equivalent proportional counter (TEPC)-based dosemeters used on the International Space Station have exceeded their planned useful lives, and are scheduled to be replaced with the new units taking advantage of improved technology. The original TEPC detectors used cylindrical geometry with field tubes to achieve good energy resolution and minimum sensitivity to noise created by vibration. The inside diameter of these detectors is 5.1 cm. The new detectors developed for this application produce the resolution and vibration resistance of the cylindrical detector with the isotropic response and compact size of a spherical detector. The cathode structure consists of conductive tissue-equivalent plastic A-150 layers separated by thin polyethylene layers perpendicular to the anode. Each conductive layer is held at the electrical potential needed to produce uniform electric field strength along the anode wire, and thus the same gas gain for electrons produced in different portions of the spherical volume. The new design contains the whole preamplifier inside the vacuum chamber to reduce electronic noise. Also the vacuum chamber has a novel design with a 0.020-inch-thick aluminium wall to allow a total wall thickness of 0.5 g cm(-2), which is typical of the shielding provided by a space suit. This feature will allow measuring the dose on the astronauts' skin due to low-energy electrons and protons produced during solar events. The vacuum chamber has a new bayonet clamping system that reduces the total detector weight to less than half that of the old TEPC. PMID:21115447

Perez-Nunez, D; Braby, L A

2011-02-01

263

Techniques for measurement of dose width product in panoramic dental radiography.  

PubMed

Dose width product (DWP) is the quantity recommended for assessment of patient dose for panoramic dental radiography. It is the product of the absorbed dose in air in the X-ray beam integrated over an exposure cycle and the width of the beam, both measured at the receiving slit. A robust method for measuring the DWP is required in order to facilitate optimization of practices and enable comparison of dose levels at different centres. In this study, three techniques for measuring the DWP have been evaluated through comparison of results from 20 orthopantomographic units. These used a small in-beam semiconductor detector and X-ray film, a pencil ionization chamber and an array of thermoluminescent dosemeters (TLDs). The mean results obtained with the three techniques agreed within +/-6%. The technique employing a pencil ionization chamber of the type used for dose assessment of CT scanners is the simplest and most reliable method. The in-beam detector and film method has larger errors both from positioning the radiation detector and from measurement of X-ray beam width, which should be the full width at half maximum obtained from a scan of the film optical density. The TLD array method was accurate, but more time consuming to carry out. The mean DWP for the units studied was 65 mGy mm and the mean dose-area product was 89 mGy cm2. The DWP for 30% of the units tested exceeded the diagnostic reference dose of 65 mGy mm, recommended by the National Radiological Protection Board. PMID:16489195

Doyle, P; Martin, C J; Robertson, J

2006-02-01

264

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

265

A single plan solution to chest wall radiotherapy with bolus?  

PubMed

Objective: Radiotherapy treatments of post-mastectomy chest walls are complex, requiring treatment close to skin, necessitating bolus use. Commonly used 5- and 10-mm-thick boluses develop full skin dose, needing removal for the latter half of treatment and requiring two treatment plans to be generated. Can a thinner bolus be used for all treatment fractions, requiring only one plan? Methods: Investigation of doses received using (A) a half-time 10-mm-thick Vaseline® bolus (current situation); (B) a brass mesh (Whiting & Davis, Attleboro Falls, MA) and (C) 3- and 5-mm Superflab™ (Mick Radio-Nuclear Instruments, Mount Vernon, NY) for 6 and 15?MV. Dosimetric measurements in Barts WT1 solid water and an anthropomorphic phantom, using ionization chambers and thermoluminescent dosemeters, were used to study the effect of different bolus regimes on the photon depth-dose curves (DDCs) and skin doses. Results: Measured skin doses for the current 10-mm-thick Vaseline bolus, brass mesh and 3-mm bolus were compared (5?mm bolus has been rejected). The brass mesh has the least effect on the DDC, with changes <0.7% for depths greater than dmax. Brass mesh conforms superiorly to skin surfaces. Measurements on an anthropomorphic phantom demonstrate an increased skin dose compared with our current treatment protocol. Conclusion: Brass mesh has the smallest effect on the DDC, whilst sufficiently increasing surface dose. It can be removed at any fraction, based on a clinical decision, without the need for generating a new plan. Treating with one plan significantly reduces planning times. Advances in knowledge: Quantification of skin doses required and achieved from wax-on/wax-off treatment compared with alternative available breast boluses. PMID:24646288

Ordonez-Sanz, C; Bowles, S; Hirst, A; Macdougall, N D

2014-05-01

266

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.

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

2013-01-01

267

Understanding the dosimetric powder EPR spectrum of sucrose by identification of the stable radiation-induced radicals.  

PubMed

Sucrose, the main component of table sugar, present in nearly every household and quite radiation sensitive, is considered as an interesting emergency dosemeter. Another application of radiation-induced radicals in sugars is the detection of irradiation in sugar-containing foodstuffs. The complexity of electron paramagnetic resonance (EPR) spectra of radicals in these materials, as a result of many hyperfine interactions and the multi-compositeness of the spectra of individual sugars, complicate dose assessment and the improvement of protocols for control and identification of irradiated sugar-containing foodstuffs using EPR. A thorough understanding of the EPR spectrum of individual irradiated sugars is desirable when one wants to reliably use them in a wide variety of dosimetric applications. Recently, the dominant room temperature stable radicals in irradiated sucrose have been thoroughly characterised using EPR, electron nuclear double resonance (ENDOR) and ENDOR-induced EPR. These radicals were structurally identified by comparing their proton hyperfine and g-tensors with the results of Density Functional Theory calculations for test radical structures. In this paper, the authors use the spin Hamiltonian parameters determined in these studies to simulate powder EPR spectra at the standard X-band (9.5 GHz), commonly used in applications, and at higher frequencies, up to J-band (285 GHz), rendering spectra with higher resolution. A few pitfalls in the simulation process are highlighted. The results indicate that the major part of the dosimetric spectrum can be understood in terms of three dominant radicals, but as-yet unidentified radicals also contribute in a non-negligible way. PMID:24865804

Vrielinck, H; Kusakovskij, J; Vanhaelewyn, G; Matthys, P; Callens, F

2014-06-01

268

TLD-100 thermoluminescent efficiencies for low-energy ions: correlation of efficiency with ion incident energy  

NASA Astrophysics Data System (ADS)

A systematic investigation of heavy charged particle-to-gamma thermoluminescent (TL) efficiencies has been performed for the total signal and peak 5 of LiF : Mg,Ti (TLD-100) dosemeters. Experimental and theoretical efficiencies are presented for protons as well as helium, carbon, nitrogen and oxygen ions. Proton, helium and carbon irradiations were performed at incident energies between 0.7 and 11 MeV. For nitrogen and oxygen, two energies, corresponding to 'mirror' values below and above the Bragg peak energy, were used to measure TL efficiencies for the same linear energy transfer (LET) entrance value. The energies chosen were 4.83 and 9.95 MeV for nitrogen ions and 6.02 and 12.95 MeV for oxygen ions. Distinct curves are found for each ion species. Data for energies higher than the Bragg peak energy follow the well-known tendency, efficiency values decrease with increasing LET. Efficiencies measured below the Bragg peak display the opposite effect, efficiency increases with increasing LET. Presenting results as a function of incident energy shows a monotonic and single valued behaviour, efficiency decreases with decreasing energy. The measured efficiencies of the higher-energy data (above the Bragg peak) were found to be 1.45 times greater than their low-energy counterparts. Modified track structure theory efficiency calculations were performed for all the ions investigated using radial dose distributions obtained via Monte Carlo simulations in solid-state LiF and 8.1 keV x-rays as test radiation. The theoretical values show agreement with data within 40% for both peak 5 and the total signal. The calculations predict the observed behaviour, higher efficiency for higher ion energy.

Ávila, O.; Rodríguez-Villafuerte, M.; Avilés, P.; Gamboa-de Buen, I.; Buenfil, A. E.; Ruiz-Trejo, C.; Concha, K.; Brandan, M. E.

2006-05-01

269

Comparison of various techniques for the exact determination of absorbed dose in heavy ion fields using passive detectors  

NASA Astrophysics Data System (ADS)

Passive thermoluminescent detectors (TLDs) are commonly applied for the determination of absorbed dose in routine radiation protection. The usage of TLDs in heavy ion fields, e.g. for treatment planing in radiotherapy or in space dosimetry, requires the detailed knowledge of the efficiency of these detectors to the ion under study in dependence on the LET of the ion. This is due to the fact, that the detection efficiency of TLDs changes with increasing LET. This would lead - if the changing efficiency of the TL- material is not taken into account - to a measured deviation of the absorbed dose. In the framework of the ICCHIBAN project - which was started as an intercomparison of passive and active detector systems used for dose determination in space - "Blind" exposures were carried out. No information about dose and ion species was given for the investigators. Three different methods were used for the efficiency correction of TLDs after the BLIND exposures. The first method used the different LET efficiency of the TL-materials LiF: Mg, Ti and LiF:Mg, Cu,P to determine the LET and based on this value the efficiency of the LiF: Mg, Ti dosemeters. The second method used the high temperature emissions in LiF: Mg, Ti for the efficiency correction. The third method applied used a combination of TLDs and CR-39 track etch detectors to determine the total absorbed dose during the BLIND exposures. The paper will discuss the threee methods, and focus on the applicability for the usage of these methods for dose determination and recalculation in space dosimetry.

Berger, T.; Reitz, G.; Hajek, M.; Vana, N.

270

Comparison of various techniques for the exact determination of absorbed dose in heavy ion fields using passive detectors  

NASA Astrophysics Data System (ADS)

Passive thermoluminescent detectors (TLDs) are commonly applied for the determination of absorbed dose in routine radiation protection. The usage of TLDs in heavy ion fields, e.g., in space dosimetry or for treatment planing in radiotherapy, requires the detailed knowledge of the efficiency of these detectors to the ion under study in dependence on the LET of the ion. This is due to the fact, that the detection efficiency of TLDs changes with increasing LET. If the changing efficiency of the TL-material is not taken into account, this would lead to a deviation of the measured absorbed dose. In the framework of the ICCHIBAN project - which was started as an intercomparison of passive and active detector systems used for dose determination in space - "BLIND" exposures were carried out. No information about dose and ion species was given to the investigators. Three different methods were used for the efficiency correction of TLDs after the BLIND exposures. The first method used the different LET efficiency of the TL-materials LiF:Mg, Ti and LiF:Mg, Cu, P to determine the LET and from this LET the efficiency of the LiF:Mg, Ti dosemeters. The second method used the high temperature emissions in LiF:Mg, Ti for the efficiency correction. The third method used a combination of TLDs and CR-39 track etch detectors to determine the total absorbed dose during the BLIND exposures. The paper will discuss the three methods, and focus on their applicability to precise dose determination and recalculation in space dosimetry.

Berger, T.; Reitz, G.; Hajek, M.; Vana, N.

271

Assessment of GeB doped SiO2 optical fiber for the application of remote radiation sensing system  

NASA Astrophysics Data System (ADS)

The research and development efforts on the silica (SiO2) optical fiber for application in radiation sensing and other dosimetry field have become quite active. The widely used LiF based dosimeter (TLD) has shown a relatively low reproducibility and there is a time delay in dose assessment which loses its capability as direct real-time dose assessment dosimeters unlike diodes. The macroscopic size of the optical fiber generally does not allow direct in vivo dose sensing in the inner organ for radiotherapy and medical imaging. A flat optical fiber (FF) with nominal dimensions of (0.08 x10 x 10) mm3 of pure silica SiO2 and GeO2 with Boron doped silica fiber SiO2 was selected for this research. The Germanium was used a dopant to enhance the flat optical fiber to reach much higher responsiveness and dose sensitivity in high energy and high dose irradiation. Together with this combination, both TLD dimension and dose assessment issues was hoped to be overcome. The research conducted by comparing the response of pure silica SiO2 flat optical fiber with a GeO2 with Boron doped silica SiO2 flat optical fiber. The FF sample was annealed at 400°C for one hour before irradiated. Kinetic parameters and dosimetric glow curve of TL response and sensitivity were studied with respect to the electron beam of high dose of micro beam irradiation of 1.0 kGy, 5.0 kGy, 10.0 kGy, 50.0 kGy, 100.0 kGy, 500.0 kGy, and 1.0 MGy using Singapore Synchrotron Light Source's (PCIT) beamline. The PCIT operates at 500mA current with real time current range from 90-100mA, dose rate of 3.03 MGy/hour and energy at 8.9KeV. The source to Source Surface Distance (SSD) was at 6.0 cm, with a field size of 20mm × 8mm diameter of a half circle. The TL response was measured using a TLD reader Harshaw Model 3500. The Time-Temperature-Profile (TTP) of the reader was obtained to a preheat temperature of 150 °C for 5 s, the output signal being acquired at a temperature ramprate of 35 °Cs-1, acquisition time of 10 s and a maximum temperature of 400 °C each of the FF samples. All reading was taken under N2 gas flow, suppressing oxidation and potential triboluminescence. The proposed FF shows the excellent TL response for high energy irradiation and good reproducibility and exhibits a very low rate of fading and low variation background signal. From these results, the proposed FF can be used as a radiation dosimeter in remote radiation sensing and favorably compares with the widely used of LiF based dosimeter on common medical radiotherapy application.

Alawiah, A.; Fadhli, M. M.; Bauk, S.; Abdul-Rashid, H. A.; Maah, M. J.

2013-12-01

272

Determination of absorbed dose to water around a clinical HDR {sup 192}Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response  

SciTech Connect

Purpose: Experimental radiation dosimetry with thermoluminescent dosimeters (TLDs), calibrated in a {sup 60}Co or megavoltage (MV) photon beam, is recommended by AAPM TG-43U1for verification of Monte Carlo calculated absorbed doses around brachytherapy sources. However, it has been shown by Carlsson Tedgren et al.[Med. Phys. 38, 5539-5550 (2011)] that for TLDs of LiF:Mg,Ti, detector response was 4% higher in a {sup 137}Cs beam than in a {sup 60}Co one. The aim of this work was to investigate if similar over-response exists when measuring absorbed dose to water around {sup 192}Ir sources, using LiF:Mg,Ti dosimeters calibrated in a 6 MV photon beam. Methods: LiF dosimeters were calibrated to measure absorbed dose to water in a 6 MV photon beam and used to measure absorbed dose to water at distances of 3, 5, and 7 cm from a clinical high dose rate (HDR) {sup 192}Ir source in a polymethylmethacrylate (PMMA) phantom. Measured values were compared to values of absorbed dose to water calculated using a treatment planning system (TPS) including corrections for the difference in energy absorption properties between calibration quality and the quality in the users'{sup 192}Ir beam and for the use of a PMMA phantom instead of the water phantom underlying dose calculations in the TPS. Results: Measured absorbed doses to water around the {sup 192}Ir source were overestimated by 5% compared to those calculated by the TPS. Corresponding absorbed doses to water measured in a previous work with lithium formate electron paramagnetic resonance (EPR) dosimeters by Antonovic et al. [Med. Phys. 36, 2236-2247 (2009)], using the same irradiation setup and calibration procedure as in this work, were 2% lower than those calculated by the TPS. The results obtained in the measurements in this work and those obtained using the EPR lithium formate dosimeters were, within the expanded (k = 2) uncertainty, in agreement with the values derived by the TPS. The discrepancy between the results using LiF:Mg,Ti TLDs and the EPR lithium formate dosimeters was, however, statistically significant and in agreement with the difference in relative detector responses found for the two detector systems by Carlsson Tedgren et al. [Med. Phys. 38, 5539-5550 (2011)] and by Adolfsson et al.[Med. Phys. 37, 4946-4959 (2010)]. Conclusions: When calibrated in {sup 60}Co or MV photon beams, correction for the linear energy transfer (LET) dependence of LiF:Mg,Ti detector response will be needed as to measure absorbed doses to water in a {sup 192}Ir beam with highest accuracy. Such corrections will depend on the manufacturing process (MTS-N Poland or Harshaw TLD-100) and details of the annealing and read-out schemes used.

Carlsson Tedgren, Aasa; Elia, Rouba; Hedtjaern, Haakan; Olsson, Sara; Alm Carlsson, Gudrun [Radiation Physics, Department of Medical and Health Sciences (IMH), Faculty of Health Sciences, Linkoeping University, SE 581 85 Linkoeping (Sweden) and Swedish Radiation Safety Authority, SE 171 16 Stockholm (Sweden); Radiation Physics, Department of Medical and Health Sciences (IMH), Faculty of Health Sciences, Linkoeping University, SE 581 85 Linkoeping (Sweden); Radiation Physics, Department of Medical and Health Sciences (IMH), Faculty of Health Sciences, Linkoeping University, SE 581 85 Linkoeping (Sweden) and Department of Radiation Physics UHL, County Council of Oestergoetland, SE 581 85 Linkoeping (Sweden); Radiation Physics, Department of Medical and Health Sciences (IMH), Faculty of Health Sciences, Linkoeping University, SE 581 85 Linkoeping (Sweden)

2012-02-15

273

Determination of nuclear tracks parameters on sequentially etched PADC detectors  

NASA Astrophysics Data System (ADS)

Polyallyl Diglycol Carbonate (PADC) detectors find many applications in radiation protection. One of them is the cosmic radiation dosimetry, where PADC detectors measure the linear energy transfer (LET) spectra of charged particles (from protons to heavy ions), supplementing TLD detectors in the role of passive dosemeter. Calibration exposures to ions of known LET are required to establish a relation between parameters of track observed on the detector and LET of particle creating this track. PADC TASTRAK nuclear track detectors were exposed to 12 C and 56 Fe ions of LET in H2 O between 10 and 544 keV/µm. The exposures took place at the Heavy Ion Medical Accelerator (HIMAC) in Chiba, Japan in the frame of the HIMAC research project "Space Radiation Dosimetry-Ground Based Verification of the MATROSHKA Facility" (20P-240). Detectors were etched in water solution of NaOH with three different temperatures and for various etching times to observe the appearance of etched tracks, the evolution of their parameters and the stability of the etching process. The applied etching times (and the solution's concentrations and temperatures) were: 48, 72, 96, 120 hours (6.25 N NaOH, 50 O C), 20, 40, 60, 80 hours (6.25 N NaOH, 60 O C) and 8, 12, 16, 20 hours (7N NaOH, 70 O C). The analysis of the detectors involved planimetric (2D) measurements of tracks' entrance ellipses and mechanical measurements of bulk layer thickness. Further track parameters, like angle of incidence, track length and etch rate ratio were then calculated. For certain tracks, results of planimetric measurements and calculations were also compared with results of optical track profile (3D) measurements, where not only the track's entrance ellipse but also the location of the track's tip could be directly measured. All these measurements have been performed with the 2D/3D measurement system at DLR. The collected data allow to create sets of V(LET in H2 O) calibration curves suitable for short, intermediate and long etching time and will be use during analysis of detectors exposed on the International Space Station during DOSIS and MATROSHKA experiments. The help and support of Yukio Uchihori and Hisashi Kitamura during the irradiations at HIMAC is highly appreciated. This work was supported by the Polish Ministry of Science and Higher Education, grants: No N N505 261535 and No. DWM/N118/ESA/2008.

Horwacik, Tomasz; Bilski, Pawel; Koerner, Christine; Facius, Rainer; Berger, Thomas; Nowak, Tomasz; Reitz, Guenther; Olko, Pawel

274

A CCD-based optical CT scanner for high-resolution 3D imaging of radiation dose distributions: equipment specifications, optical simulations and preliminary results  

NASA Astrophysics Data System (ADS)

Methods based on magnetic resonance imaging for the measurement of three-dimensional distributions of radiation dose are highly developed. However, relatively little work has been done on optical computed tomography (OCT). This paper describes a new OCT scanner based on a broad beam light source and a two-dimensional charge-coupled device (CCD) detector. A number of key design features are discussed including the light source; the scanning tank, turntable and stepper motor control; the diffuser screen onto which images are projected and the detector. It is shown that the non-uniform pixel sensitivity of the low-cost CCD detector used and the granularity of the diffuser screen lead to a serious ring artefact in the reconstructed images. Methods are described for eliminating this. The problems arising from reflection and refraction at the walls of the gel container are explained. Optical ray-tracing simulations are presented for cylindrical containers with a variety of radii and verified experimentally. Small changes in the model parameters lead to large variations in the signal intensity observed in the projection data. The effect of imperfect containers on data quality is discussed and a method based on a 'correction scan' is shown to be successful in correcting many of the related image artefacts. The results of two tomography experiments are presented. In the first experiment, a radiochromic Fricke gel sample was exposed four times in different positions to a 100 kVp x-ray beam perpendicular to the plane of imaging. Images of absorbed dose with slice thickness of 140 ?m were acquired, with 'true' in-plane resolution of 560 × 560 ?m2 at the edge of the 72 mm field of view and correspondingly higher resolution at the centre. The nominal doses measured correlated well with the known exposure times. The second experiment demonstrated the well known phenomenon of diffusion in the dosemeter gels and yielded a value of (0.12 +/- 0.02) mm2 s-1 for the diffusion coefficient of the xylenol orange/iron complex. Finally, the overall implications of the above findings for dosimetry using OCT are discussed.

Doran, Simon J.; Klein Koerkamp, Koen; Bero, Mamdouh A.; Jenneson, Paul; Morton, Edward J.; Gilboy, Walter B.

2001-12-01

275

Simultaneous measurements of radon and thoron, and their progeny levels in dwellings on anticlinal structures of Assam, India.  

PubMed

Radon and thoron, and their progeny concentrations along with equilibrium factors for gas progeny and radiological risks to the residents have been measured in dwellings of Digboi and Mashimpur areas located on anticlines during the winter season. In this present investigation, twin-cup dosemeters fitted with LR-115 (II) nuclear detectors have been employed. The present work has shown that there exist considerable house-to-house variations in values with maximum values in mud houses and minimum values in assam type (AT) houses. It has been found that mean (and geometric standard deviations (GSD)) radon concentrations are 83.8 (1.3), 113.5 (1.1) and 157.2 (1.2) Bq m(-3) in AT, reinforced cement concrete (RCC) and mud houses in Digboi area and 63.0 (1.1), 87.1 (1.4) and 182.1 (1.2) Bq m(-3) in AT, RCC and mud houses in Mashimpur area, respectively. The overall mean radon concentrations in Digboi and Mashimpur are estimated to be 114.4 (1.4) and 100.0 (1.7) Bq m(-3). The mean radon concentrations are found to be less than the lower reference level of 200 Bq m(-3) of the International Commission on Radiological Protection (ICRP 2007). The thoron concentrations in Digboi area are estimated to be 31.1 (1.3), 50.8 (1.4) and 67.0 (1.6) Bq m(-3) in AT, RCC and mud houses, respectively, whereas in Mashimpur area, the thoron concentrations are estimated to be 26.4 (1.3), 44.4 (1.3) and 77.7 (1.3) Bq m(-3) in AT, RCC and mud houses, respectively. The mean annual effective doses in Digboi area are found to be 1.9 (1.3), 2.7 (1.2) and 4.1 (1.4) mSv y(-1) in AT, RCC and mud houses, respectively, while in the case of Mashimpur area, the mean annual effective doses are found to be 1.5 (1.4), 2.2 (1.2) and 4.9 (1.3) mSv y(-1) in AT, RCC and mud houses, respectively. Nevertheless, the obtained results are much lower than the upper reference level of 10 mSv (ICRP 2007). PMID:24469015

Barooah, Debajyoti; Barman, Simi; Phukan, Sarat

2014-06-01

276

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

277

Assessment of annual whole-body occupational radiation exposure in medical practice in Ghana (2000-09).  

PubMed

Occupational exposure to radiation in medical practice in Ghana has been analysed for a 10-y period between 2000 and 2009. Monitored dose data in the medical institution in Ghana from the Radiation Protection Institute's database were extracted and analysed in terms of three categories: diagnostic radiology, radiotherapy and nuclear medicine. One hundred and eighty medical facilities were monitored for the 10-y period, out of which ~98% were diagnostic radiology facilities. Only one nuclear medicine and two radiotherapy facilities have been operational in the country since 2000. During the 10-y study period, monitored medical facilities increased by 18.8%, while the exposed workers decreased by 23.0%. Average exposed worker per entire medical institution for the 10-y study period was 4.3. Annual collective dose received by all the exposed workers reduced by a factor of 4 between 2000 and 2009. This is seen as reduction in annual collective doses in diagnostic radiology, radiotherapy and nuclear medicine facilities by ~76, ~72 and ~55%, respectively, for the 10-y period. Highest annual collective dose of 601.2 man mSv was recorded in 2002 and the least of 142.6 man mSv was recorded in 2009. Annual average values for dose per institution and dose per exposed worker decreased by 79 and 67.6%, respectively between 2000 and 2009. Average dose per exposed worker for the 10-y period was least in radiotherapy and highest in diagnostic radiology with values 0.14 and 1.05 mSv, respectively. Nuclear medicine however recorded average dose per worker of 0.72 mSv. Correspondingly, range of average effective doses within the diagnostic radiology, radiotherapy and nuclear medicine facilities were 0.328-2.614, 0.383-0.728 and 0.448-0.695 mSv, respectively. Throughout the study period, an average dose per medical institution of 3 mSv and an average dose per exposed worker of 0.69 mSv were realised. Exposed workers in diagnostic radiology primarily received most of the individual annual doses >1 mSv. The entire study period had 705 instances in which exposed workers received individual annual doses >1 mSv. On thermoluminescent dosemeter (TLD) return rates, facilities in Volta and Eastern Regions recorded highest return rates of 94.3% each. Ashanti Region recorded the least TLD return rate with 76.7%. PMID:21743072

Hasford, F; Owusu-Banahene, J; Amoako, J K; Otoo, F; Darko, E O; Emi-Reynolds, G; Yeboah, J; Arwui, C C; Adu, S

2012-05-01