These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

PubMed

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

Veinot, K G; Hertel, N E

2005-01-01

2

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

PubMed

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

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

2011-03-01

3

FACTS II (Aspen FACE) Facility and Harshaw Forest Experimental Farm Facility  

E-print Network

June 2002 FACTS II (Aspen FACE) Facility and Harshaw Forest Experimental Farm Facility Site*, and Wendy Jones* *School of Forestry and Wood Products, Michigan Technological University, 1400 Townsend;Project Name: Forest Atmosphere Carbon Transfer and Storage (FACTS-II) The Aspen Free-air CO2 and O3

4

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

PubMed

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

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

2011-03-01

5

Review of international standards for dosemeters.  

PubMed

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

Behrens, R; Ambrosi, P

2008-01-01

6

Comparison on characteristics of radiophotoluminescent glass dosemeters and thermoluminescent dosemeters.  

PubMed

The radiophotoluminescent glass dosemeter (RPLGD) system is applicable for measurement of radiation dose of X rays and gamma rays by using radiophotoluminescent glass (silver-activated phosphate glass). When the radiophotoluminescent glass is exposed to ionizing radiation, stable luminescent centres are created. During pulsed ultraviolet laser excitation (337.1 nm) in the reader, the centres emit a radiation induced orange fluorescent light (600-700 nm). This phenomenon is called radiophotoluminescence. This study compared the RPLGD system with lithium fluoride (LiF) thermoluminescence dosimetry system and the results of the study revealed that the RPLGD had not only good basic characteristics for reproducibility of readout value, dose linearity, energy dependence and fading, but also infinite repeatable measurements and could be one of the most important radiation dose measurement instruments. PMID:16709718

Hsu, Shih-Ming; Yeh, Shann-Horng; Lin, Meei-Shiow; Chen, Wei-Li

2006-01-01

7

Fast neutron dosemeter using pixelated detector Timepix.  

PubMed

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

Bulanek, Boris; Ekendahl, Daniela; Prouza, Zdenek

2014-10-01

8

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

9

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

10

Active neutron dosemeters based on microdosimetric principles: research studies.  

PubMed

Over the past few years, the Institute for Radiation Protection and Nuclear Safety (IRSN) has been studying a personal electronic neutron dosemeter and an ambient electronic neutron dosemeter based on experimental microdosimetric principles using low pressure proportional counters. The results obtained in 2000 and in 2001 with the cylindrical tissue-equivalent proportional counter developed for use in radiation protection and filled with a low pressure tissue-equivalent gas (propane based) are presented here. PMID:12194330

Ménard, S; Chau, Q; Lahaye, T

2002-01-01

11

Dose measurement for medical staff with glass dosemeters and thermoluminescence dosemeters during 125I brachytherapy for prostate cancer.  

PubMed

Photoluminescence glass dosemeters (PLDs) and thermoluminescence dosemeters (TLDs) are commonly used as a personal monitoring dosemeter. PLDs and TLDs were used for surface dose monitoring of medical staff involved in (125)I brachytherapy for prostate cancer because these dosemeters have a wide dose-response linearity and high sensitivity for low photon energy. Surface doses measured with PLDs agreed with those with TLDs within ?20 % except for a few cases. Surface doses at a surgeon's left hand and arm were higher than those at the other measuring points. A surgeon received a maximum dose of 650 ?Gy at the back of left hand. Surface doses to an assistant were <100 ?Gy. Surface doses to a nurse, a radiologist, an anaesthesiologist and a radiological technologist were <10 ?Gy. The occupational exposure to a surgeon could be reduced by the adjustment of fluoroscopic parameters and the use of lead gloves. PMID:21212076

Fujii, K; Ko, S; Nako, Y; Tonari, A; Nishizawa, K; Akahane, K; Takayama, M

2011-03-01

12

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

PubMed

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

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

2011-03-01

13

Study of the photon radiation performance of electronic personal dosemeters.  

PubMed

Following the specifications and test methods given by international standards IEC-61526 and ISO 4037, the dosimetry department of the IPSN studied the photon radiation performance of seven recent electronic personal dosemeters: The personal dosimetric performance of each piece of equipment was tested with X and gamma radiation between 12 keV and 1.25 MeV. PMID:11586741

Texier, C; Itié, C; Servičre, H; Gressier, V; Bolognese-Milsztajn, T

2001-01-01

14

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

15

Type testing of the Siemens Plessey electronic personal dosemeter.  

PubMed

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

Hirning, C R; Yuen, P S

1995-07-01

16

Response of alanine and radio-photo-luminescence dosemeters to mixed high-energy radiation fields.  

PubMed

Alanine and Radio-Photo-Luminescence (RPL) dosemeters are passive dosemeters used to monitor absorbed dose in all kind of radiation fields. However, up to now both dosemeter types are calibrated to photon sources only. In order to study the response of RPL and alanine dosemeters to mixed high-energy particle fields like those occurring at CERN's accelerators, an irradiation campaign at the CERN-EC High-Energy Reference field Facility (CERF-field) was performed. In this facility a copper target is irradiated by hadrons with a momentum of 120 GeV/c. Dosemeters were exposed to various mixed radiation fields by placing them at various positions on the surface of the target. In addition to the experiment FLUKA Monte Carlo simulations were carried out, which provide information concerning the energy deposition at the dosemeter locations. This paper compares the measurements with the simulation results and discusses the radiation field compositions present at the various dosemeter positions on the target. PMID:17369266

Vincke, H; Brunner, I; Floret, I; Forkel-Wirth, D; Fuerstner, M; Mayer, S; Theis, C

2007-01-01

17

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

PubMed

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

Voytchev, M

2014-10-01

18

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

PubMed

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

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

2014-10-01

19

The first operational dosemeter for neutrons which complies with IEC standard 1323.  

PubMed

Individual neutron dosimetry represents one of the current difficulties in the field of radiological protection of workers. Since March 1999, the regulatory requirements in France for active (i.e. operational) dosimetry have been those of ICRP Publication 60, applicable from May 2000, necessitating the introduction of a new generation of neutron dosemeters. Over the last few years, the Institute for Nuclear Safety and Protection has been studying an individual electronic dosemeter for neutrons based on a semiconducting detector, capable of meeting the specifications laid down by a neutron dosimetry work group, including members from all the main players in the French nuclear industry. In 1998, the IPSN began transferring technology to the Saphymo company which, by the end of 2001, will be marketing Saphydose-n, the first individual dosemeter for neutrons which complies with IEC Standard 1323. This dosemeter is of compact design and can assess the individual dose equivalent Hp(10) in mixed neutron and gamma radiation fields. It wil be usable in any nuclear facility without prior knowledge of the average neutron spectrum or of the neutron-gamma ratio. It will be possible to connect the Saphydose-n dosemeter to any of the existing gamma deserter terminals to read the dose data and recharge the batteries. PMID:11586740

Lahaye, T; Cutarella, D; Ménard, S; Bolognese-Milsztajn, T

2001-01-01

20

VALIDATION OF A MOSFET DOSEMETER SYSTEM FOR DETERMINING THE ABSORBED AND EFFECTIVE RADIATION DOSES IN DIAGNOSTIC RADIOLOGY.  

PubMed

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

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

2014-09-11

21

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

22

Qualification of the bubble detector as neutron dosemeter at the MOX plant of BELGONUCLEAIRE  

NASA Astrophysics Data System (ADS)

Due to the increasing contribution of the neutron dose to the total dose of the BELGONUCLEAIRE personnel and the introduction of the ICRP 60 recommendations,1 the use of a more reliable personal neutron dosemeter has become even more important. A Canadian2 dosimeter manufactured by Bubble Technology Industries seemed to be a very interesting alternative to the albedo dosimeter used in the past. An extensive investigation program was carried out at BELGONUCLEAIRE to determine the effectiveness of the new dosimeter in the fuel fabrication plant environment. A series of tests were conducted to get a better understanding of this type of dosemeter.

Kockerols, P.; De Smet, F.; Vandergheynst, A.

2000-07-01

23

Long-term PTB intercomparison of passive H*(10) dosemeters used in area monitoring  

NASA Astrophysics Data System (ADS)

This intercomparison serves to investigate the long-term behaviour of passive (or similarly used active) H*(10) dosemeters which are dedicated to the monitoring of the surroundings of nuclear plants and accelerators and used in the radiation field of the natural ambient radiation. From autumn 2005 to spring 2007, approx. 650 photon and neutron dosemeters were exposed to environmental radiation at three dosimetric reference sites, operated by the Physikalisch-Technische Bundesanstalt (PTB). In addition to the measurements under natural conditions a number of dosemeters was also subjected to an additional irradiation in PTB photon and neutron fields. Ten measuring bodies and institutions, which are involved in ambient monitoring in Germany, Austria and Switzerland, took part in this intercomparison. The intercomparison revealed the typical precision to be expected from long-term dose measurements in the natural environment. The difference of the response of the dosemeters to terrestrial and to cosmic radiation was determined. From the results of this intercomparison some sources of uncertainty were identified and some recommendations to improve area monitoring were derived.

Dombrowski, H.; Neumaier, S.

2012-04-01

24

Simulated and measured Hp(10) response of the personal dosemeter Seibersdorf.  

PubMed

The Hp(10) energy response of the personal dosemeter Seibersdorf and its two different filtered LiF:Mg,Ti (TLD-100) thermoluminescence (TL) detectors are investigated. A close-to-reality simulation model of the personal dosemeter badge including the wrapped detector card was implemented with the MCNP Monte Carlo N-particle transport code. The comparison of measured and computationally calculated response using a semi-empirical TL efficiency function is carried out to provide information about the quality of the results of both methods, experiment and simulation. Similar to the experimental calibration conditions, the irradiation of dosemeters centred on the front surface of the International Organization for Standardization (ISO) water slab phantom is simulated using ISO-4037 reference photon radiation qualities with mean energies between 24 keV and 1.25 MeV and corresponding ISO conversion coefficients. The comparison of the simulated and measured relative Hp(10) energy responses resulted in good agreement within some percent except for the filtered TL element at lower photon energies. PMID:17846027

Hranitzky, C; Stadtmann, H

2007-01-01

25

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

26

Assessment of neutron dosemeters around standard sources and nuclear fissile objects.  

PubMed

In order to evaluate the neutron doses around nuclear fissile objects, a comparative study has been made on several neutron dosemeters: bubble dosemeters, etched-track detectors (CR-39) and 3He-filled proportional counters used as dose-rate meters. The measurements were made on the ambient and the personal dose equivalents H*(10) and Hp(10). Results showed that several bubble dosemeters should have been used due to a low reproducibility in the measurements. A strong correlation with the neutron energy was also found, with about a 30% underestimation of Hp(10) for neutrons from the PuBe source, and about a 9% overestimation for neutrons from the 252Cf source. Measurements of the nuclear fissile objects were made using the CR-39 and the dose-rate meters. The CR-39 led to an underestimation of 30% with respect to the neutron dose-rate meter measurements. In addition, the MCNP calculation code was used in the different configurations. PMID:12382734

Raimondi, N; Tournier, B; Groetz, J E; Piot, J; Riebler, E; Crovisier, P; Chambaudet, A; Cabanné, N

2002-01-01

27

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

NASA Astrophysics Data System (ADS)

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

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

1998-12-01

28

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

PubMed

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

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

2014-10-01

29

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

30

Development of a new electronic personal neutron dosemeter using a CMOS active pixel sensor.  

PubMed

A CMOS active pixel sensor, originally designed for the tracking of minimum ionising charged particles in high-energy physics, has been recently used for the detection of fast neutrons. Data were taken at the IRSN Cadarache facility with a (241)Am-Be ISO source and a polyethylene radiator. A high-intrinsic efficiency (1.2 x 10(-3)) has been obtained. It is in good agreement with both calculations and a MCNPX Monte Carlo simulation. This experiment paves the way for a fully electronic personal neutron dosemeter. PMID:17576655

Trocmé, M; Higueret, S; Husson, D; Nourreddine, A; Lę, T D

2007-01-01

31

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

32

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

PubMed

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

van Dijk, J W E

2014-12-01

33

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

34

SCIENTIFIC NOTE: The effect of radiation on bioluminescent bacteria: possible use of luminescent bacteria as a biological dosemeter  

Microsoft Academic Search

Reports investigations on the response of the bioluminescent bacteria, Photobacterium phosphoreum, to radiation and the use of the bacteria as a biological radiation dosemeter. By the latter the authors mean a water-equivalent biological system that will compare beams not merely on the basis of absorbed dose, but also have intrinsic RBE values for different radiation beams. The authors studied the

J. Mantel; M. Freidin; A. A. Bulich; H. Perry

1983-01-01

35

Exposure of aircraft crew to cosmic radiation: on-board intercomparison of various dosemeters.  

PubMed

Owing to their professional activity, flight crews may receive a dose of some millisieverts within a year; airline passengers may also be concerned. The effective dose is to be estimated using various experimental and calculation tools. The European project DOSMAX (Dosimetry of Aircrew Exposure during Solar Maximum) was initiated in 2000 extending to 2004 to complete studies over the current solar cycle during the solar maximum phase. To compare various dosemeters in real conditions simultaneously in the same radiation field, an intercomparison was organised aboard a Paris-Tokyo round-trip flight. Both passive and active detectors were used. Good agreement was observed for instruments determining the different components of the radiation field; the mean ambient dose equivalent for the round trip was 129 +/- 10 microSv. The agreement of values obtained for the total dose obtained by measurements and by calculations is very satisfying. PMID:15353683

Bottollier-Depois, J-F; Trompier, F; Clairand, I; Spurny, F; Bartlett, D; Beck, P; Lewis, B; Lindborg, L; O'Sullivan, D; Roos, H; Tommasino, L

2004-01-01

36

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

PubMed

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

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

2012-01-01

37

Application of whole-body personal TL dosemeters in mixed field beta-gamma radiation.  

PubMed

Application of whole-body personal TL dosemeters based on a high-sensitivity LiF:Mg,Cu,P (MCP-N) in mixed field beta-gamma radiation has been characterised. The measurements were carried out with (90)Sr/(90)Y, (85)Kr and (137)Cs point sources to calculate the energy response and linearity of the TLD response in a dose range of 0.1-30 mSv. From the result, calibration curves were obtained, enabling the readout of individual dose equivalent Hp(10) from gamma radiation and Hp(0.07) from beta radiation in mixed field beta-gamma. Limitation of the methodology and its application are presented and discussed. PMID:25009188

Ciupek, K; Aksamit, D; Wo?oszczuk, K

2014-11-01

38

PERFORMANCE OF THE EPD-N2 DOSEMETER FOR MONITORING AIRCREW DOSES.  

PubMed

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

Scherpelz, R I; Cezeaux, J R

2014-08-01

39

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

PubMed

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

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

2011-07-01

40

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

41

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

42

Characteristics and performance of the Sunna high dose dosemeter using green photoluminescence and UV absorption readout methods.  

PubMed

Growth in the use of ionising radiation for medical sterilisation and the potential for wide-scale international food irradiation have created the need for robust, mass-producible, inexpensive, and highly accurate radiation dosemeters. The Sunna dosemeter, lithium fluoride injection-moulded in a polyethylene matrix, can be read out using either green photoluminescence or ultraviolet (UV) absorption. The Sunna dosemeter can be mass-produced inexpensively with high precision. Both the photoluminescent and the UV absorption reader are simple and inexpensive. Both methods of analysis display negligible humidity effects, minimal dose rate dependence, acceptable post-irradiation effects, and permit measurements with a precision of nearly 1% 1sigma. The UV method shows negligible irradiation temperature effects from -30 degrees C to +60 degrees C. The photoluminescence method shows negligible irradiation temperature effects above room temperature for sterilisation dose levels and above. The dosimetry characteristics of these two readout methods are presented along with performance data in commercial sterilisation facilities. PMID:12382704

Miller, S D; Murphy, M K; Tinker, M R; Kovacs, A; McLaughlin, W

2002-01-01

43

Influence of the uniformity of the slab phantom illumination on the calibration of personal dosemeters.  

PubMed

For the calibration of personal dosemeters in terms of H(p)(10), the ISO water slab phantom shall be used. The irradiation geometry must be chosen such that the field diameter at the phantom front surface is large enough to irradiate the phantom completely and, in addition, homogeneously. However, in practice it is not always possible to achieve this, especially if high dose rates are required and hence the irradiation must be performed at short distances. The subject of this investigation is to determine the influence of the beam diameter on the calibration result or, more correctly, on the quantity value of H(p)(10). Measurements were performed with a PTB-developed secondary standard chamber for H(p)(10) at several radiation qualities of the ISO narrow-spectrum series. The results show that a reduced beam diameter of only 250 mm decreases the quantity value of H(p)(10) by a maximum of 5 %. This can be considered by adding an additional standard uncertainty of a maximum of 5 % for the quantity value of H(p)(10). PMID:20176730

Ankerhold, U; Ambrosi, P

2010-06-01

44

Active personal dosemeters in interventional radiology: tests in laboratory conditions and in hospitals.  

PubMed

The work package 3 of the ORAMED project, Collaborative Project (2008-11) supported by the European Commission within its seventh Framework Programme, is focused on the optimisation of the use of active personal dosemeters (APDs) in interventional radiology and cardiology (IR/IC). Indeed, a lack of appropriate APD devices is identified for these specific fields. Few devices can detect low-energy X rays (20-100 keV), and none of them are specifically designed for working in pulsed radiation fields. The work presented in this paper consists in studying the behaviour of some selected APDs deemed suitable for application in IR/IC. For this purpose, measurements under laboratory conditions, both with continuous and pulsed X-ray beams, and tests in real conditions on site in different European hospitals were performed. This study highlights the limitations of APDs for this application and the need of improving the APD technology so as to fulfil all needs in the IR/IC field. PMID:21186215

Clairand, I; Bordy, J-M; Daures, J; Debroas, J; Denozičre, M; Donadille, L; Ginjaume, M; Itié, C; Koukorava, C; Krim, S; Lebacq, A-L; Martin, P; Struelens, L; Sans-Mercé, M; Tosic, M; Vanhavere, F

2011-03-01

45

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

PubMed

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

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

2014-10-01

46

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

47

Uncertainty assessment of a two element LiF:Mg,Ti TL personal dosemeter using Monte-Carlo techniques.  

PubMed

This paper presents the results of an uncertainty assessment and a comparison study of dose algorithms for H(p)(10) and H(p)(0.07) used for evaluating a routine two-element thermoluminescent whole-body dosemeter. Due to the photon-energy response of the two different filtered LiF:Mg,Ti detector elements, the application of a dose algorithm is necessary to assess the relevant photon doses over the rated energy range with an acceptable energy dependence. A linear dose algorithm with two different sets of parameters was designed to assess the personal dose equivalent in the relevant quantity H(p)(10) and H(p)(0.07). Based on the experimental results from calibrations on the ISO water slab phantom, a detailed uncertainty analysis was performed by means of Monte-Carlo (MC) techniques and other analytical methods. The uncertainty contribution of the individual detector element signals was taken into special consideration. For this analysis, realistic energy and angular distributions were applied to calculate the dosemeter response. It is concluded that the MC method is an appropriate tool to perform uncertainty calculations. The possibility to assign arbitrary probability density functions to the input quantities, as well as to define a complex model function (dose algorithm) allows the simulation of irradiation conditions close to reality. PMID:21245065

Stadtmann, H; Hranitzky, C

2011-03-01

48

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

PubMed

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

Harvey, John A; Kearfott, Kimberlee J

2012-04-01

49

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. PMID:22653437

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

2013-01-01

50

Fundamental study on the characteristics of a radiophotoluminescence glass dosemeter with no energy compensation filter for measuring patient entrance doses in cardiac interventional procedures.  

PubMed

Cardiac interventional procedures have been increasing year by year. However, radiation skin injuries have been still reported. There is a necessity to measure the patient entrance skin dose (ESD), but an accurate dose measurement method has not been established. To measure the ESD, a lot of radiophotoluminescence dosemeters (RPLDs) provide an accurate measurement of the direct actual ESD at the points they are arrayed. The purpose of this study was to examine the characteristics of RPLD to measure the ESD. As a result, X-ray permeable RPLD (with no tin filter) did not interfere with the percutaneous coronary intervention procedure. The RPLD also had good fundamental performance characteristics. Although the RPLD had a little energy dependence, it showed excellent dose and dose-rate linearity, and good angular dependence. In conclusion, by calibrating the energy dependence, RPLDs are useful dosemeter to measure the ESD in cardiac intervention. PMID:24277872

Kato, Mamoru; Chida, Koichi; Moritake, Takashi; Koguchi, Yasuhiro; Sato, Tadaya; Oosaka, Hajime; Tosa, Tetsuo; Kadowaki, Ken

2014-12-01

51

Comparison of two extremity dosemeters based on LiF:Mg,Cu,P thin detectors for mixed beta-gamma fields.  

PubMed

Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in the design of an extremity dosemeter for mixed beta-photon radiation fields. Both detectors consist of an extremely thin layer of sensitive material with effective thicknesses of 5 and 8 mg cm(-2), respectively, held in a 5 mg cm(-2) PVC ring holder. Dosimetric performance was analysed according to the ISO 12794 standard and compared with 240 mg cm(-2) TLD-100 measurements. In particular, the energy response was obtained for ISO narrow X-ray spectra, (137)Cs, (60)Co, (204)Tl and (90)Sr/(90)Y. From these measurements a mean calibration factor was calculated to estimate H(p)(0.07). Subsequently, the performance of the dosemeters was checked for a set of 10 different mixed photon and beta-photon fields. The study shows that the proposed dosemeters can estimate H(p)(0.07) in a wide range of mixed beta-photon fields with a maximum deviation from the given dose of 30% and an overall uncertainty of the order of 25% (k = 1). However, the results also highlight a large variability among the different thin detectors and, thus, the standard TLD-100 material is recommended whenever the workplace does not include low-energy beta radiation. PMID:16644980

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

2006-01-01

52

Relative HCP-to-gamma Thermoluminescent Efficiencies for TLD-100 Dosemeters Exposed to Low-energy Ions  

SciTech Connect

This work presents data and calculations of (HCP)-to-gamma TLD-100 thermoluminescent efficiencies. Dosemeters were irradiated with low energy hydrogen, helium, carbon, nitrogen and oxygen ions. 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. Efficiency results, both as a function of LET and energy, show distinct curves for each ion species. For energies above the Bragg peak energy, measurements show the well known tendency, efficiency values decrease with increasing LET. Data for energies lower than the Bragg peak display the opposite, efficiency increases with increasing LET. Results presented as a function of incident energy show that efficiency decreases with decreasing energy. For nitrogen and oxygen ions, the ''mirror'' measurements at higher energy (above the Bragg peak) are found to be 1.45 times greater than their low energy counterparts. Theoretical predictions based on Modified Track Structure Theory (MTST) show agreement with data within 40 % and predict the observed behavior, higher efficiency for higher ion energy.

Avila, O. [Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, DF (Mexico); Rodriguez-Villafuerte, M.; Buenfil, A. E.; Ruiz-Trejo, C.; Concha, K.; Brandan, M. E. [Instituto de Fisica, UNAM, AP 20-364, 01000, DF (Mexico); Aviles, P. [Facultad de Ciencias, UNAM, AP 70-542, 04510, DF (Mexico); Gamboa de Buen, I. [Instituto de Ciencias Nucleares, UNAM, AP 70-543, 04510 DF (Mexico)

2006-09-08

53

Evaluation of personal dose equivalent using optically stimulated luminescent dosemeters in Marumori after the Fukushima nuclear accident.  

PubMed

The personal dose equivalent for 36 Marumori residents living in wooden houses was evaluated using optically stimulated luminescent dosemeters after the Fukushima nuclear accident. The cumulative doses to residents over 200 d from 1 September 2011 ranged from 536 to 1490 µSv. In each resident's house, the indoor and outdoor ambient dose equivalents were measured with an NaI scintillation survey meter. A linear relationship with a slope of 0.5 was found between them; however, the ratio of the indoor to the outdoor ambient dose equivalent varied from 0.36 to 1.0. A better linear relationship was observed between the personal dose equivalent and the indoor ambient dose equivalent compared with that between the personal dose equivalent and the outdoor ambient dose equivalent. These results indicate that the individual exposure dose depends on the indoor ambient dose equivalent rather than the outdoor ambient dose equivalent. These results should be very helpful in obtaining the countermeasures to reduce residents' exposure dose. PMID:22987119

Yoshida-Ohuchi, Hiroko; Hirasawa, Noriyasu; Kobayashi, Ikuo; Yoshizawa, Takeshi

2013-01-01

54

A modified lead attenuation method to determine the fast neutron sensitivity kU of a photon dosemeter.  

PubMed

Various lead attenuation techniques to determine the fast neutron sensitivity kU of a photon dosemeter are reviewed and a modified method is proposed to determine the kU value of a commercially available Geiger--Müller detector. The dependence on the 'effective' photon energy of the gamma-component of the mixed n--gamma field is illustrated and the most probable photon energy is deduced from measurements outside the radiation field. Using the relevant photon mass attenuation coefficient, measurements carried out with a well-collimated neutron beam at the MRC Cyclotron, Hammersmith Hospital, London, show that the Dg component contributes 2.41 +/- 0.13% to the total radiation field. Using a detector with a PTFE sleeve in the place of a Perspex sleeve, highly consistent results are obtained and the enhancement of the kU value by the Perspex is demonstrated. The neutron sensitivities of two MX 163 GM detectors with Perspex and PTFE sleeves were respectively determined as 0.73 +/- 0.07% and 0.98 +/- 0.14%. PMID:472010

Hough, J H

1979-07-01

55

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

56

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

PubMed Central

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

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

2013-01-01

57

Multichannel dosemeter and Al2O3:C optically stimulated luminescence fibre sensors for use in radiation therapy: evaluation with electron beams.  

PubMed

This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve. PMID:18757901

Magne, S; Auger, L; Bordy, J M; de Carlan, L; Isambert, A; Bridier, A; Ferdinand, P; Barthe, J

2008-01-01

58

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

59

The use of enriched 6Li and 7Li Lif:Mg,Cu,P glass-rod thermoluminescent dosemeters for linear accelerator out-of-field radiation dose measurements.  

PubMed

(6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P glass-rod thermoluminescent dosemeters (TLDs) were used for measurements of out-of-field photon and neutron doses produced by Varian iX linear accelerator. Both TLDs were calibrated using 18-MV X-ray beam to investigate their dose-response sensitivity and linearity. CR-39 etch-track detectors (Luxel+, Landauer) were employed to provide neutron dose data to calibrate (6)LiF:Mg,Cu,P TLDs at various distances from the isocentre. With cadmium filters employed, slow neutrons (<0.5 eV) were distinguished from fast neutrons. The average in-air photon dose equivalents per monitor unit (MU) ranged from 1.5±0.4 to 215.5±94.6 ?Sv at 100 and 15 cm from the isocentre, respectively. Based on the cross-calibration factors obtained with CR-39 etch-track detectors, the average in-air fast neutron dose equivalents per MU range from 10.6±3.8 to 59.1±49.9 ?Sv at 100 and 15 cm from the isocentre, respectively. Contribution of thermal neutrons to total neutron dose equivalent was small: 3.1±7.2 ?Sv per MU at 15 cm from the isocentre. PMID:21873634

Takam, R; Bezak, E; Liu, G; Marcu, L

2012-06-01

60

An active personal neutron dosemeter based on microdosimetric principles: CIME.  

PubMed

Over the last few years IPSN has been developing a small, tissue equivalent proportional counter (TEPC) with multielement geometry for personal radiation protection monitoring. This paper presents the last prototype, which is insensitive to microphony, and the experimental results. Numerical modelling results using CERN codes are partly presented and allow an understanding of the nuclear and electrostatic physics involved in a TEPC. PMID:11586745

Ménard, S; Cutarella, D; Lahaye, T; Bolognese-Milsztajn, T

2001-01-01

61

Preliminary results on bubble detector as personal neutron dosemeter.  

PubMed

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

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

2011-03-01

62

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

63

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

E-print Network

correction factor, the chips output could be used interchangeably. Table 1: Initial Sensitivity Data. Chi Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 TL Out ut nC 18. 580 17. 088 19. 452 18. 282 17. 562 18. 343 19. 510 19. 037 19... (nC) Ave. Output (nC) Corr. Factor 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 18. 826 17. 432 20. 276 18. 366 17. 876 18. 642 18. 664 18. 866 18. 834 18. 884 19. 744 19. 270 16. 506 20. 156 20. 898 17. 736 16. 746 19. 036 17...

McCarthy, Daniel Patrick

2012-06-07

64

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

65

The G-value for the ferrous sulphate dosemeter for the radiation from californium-252  

Microsoft Academic Search

The FeSO4 G-value for the mixed neutron and ?-radiation from californium.252 has been measured experimentally using ionization dosimetry. A value of 9.9 +- 0.7 was obtained for irradiations in air (?-component 31%) and 10.1 +- 0.8 in a scattering medium (?-component 43%). Calculated G-values for the neutron component alone were consistent with theoretical predictions.

D. Greene; J. Law; D. Major

1973-01-01

66

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

SciTech Connect

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

Vanstalle, M.; Husson, D.; Higueret, S.; Le, T. D.; Nourreddine, A. M. [Institut Pluridisciplinaire Hubert Curien, Univ. of Strasbourg, CNRS, 67037 Strasbourg (France)

2011-07-01

67

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

Microsoft Academic Search

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

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

2009-01-01

68

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

69

MODIFICATION OF SHIRT BUTTONS FOR RETROSPECTIVE RADIATION DOSIMETRY AFTER A RADIOLOGICAL EVENT  

E-print Network

as single batches of 40 Harshaw TLD-100 and TLD-100H from Thermo Electron Corporation (now Thermo Scientific manual TLD reader (Thermo Electron Corporation). The LiF:Mg,Ti rods were an- nealed at least

Brenner, David Jonathan

70

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

71

Personnel photon dosimeter on the base of TLD sup n sup a sup t LiF  

E-print Network

A personnel photon dosemeter on the basis of thermoluminescence detectors (TLD) sup n sup a sup t LiF is described. Experimental responses of the dosemeters in the unit of individual equivalent dose H sub p (10) for energy of photons 59.5, 120, 662, and 1250 keV are presented. It is shown that the dosemeter allows one to measure H sub p (10) with admissible uncertainty in the energy range from 60 to 1250 keV.

Kaskanov, G Y

2003-01-01

72

z>/r ^o ^/^^ Riso.M-2637  

E-print Network

a continuous radiation monitoring system is vety costly, it still may be necessary for detecting radioactive distribution and doso of environmental gamma radiation was developed using a multi- element TL dosemeter. Experimentally obtained energy responses from a multi-element TL dosemeter with different kinds of fil- ters were

73

C7-158 JOURNAL DE PHYSIQUE Colloque C7, supplkment au no 12, Tome 37, Dtcembre 1976 THERMOLUMINESCENCE IN ALKALINE-EARTH  

E-print Network

THERMOLUMINESCENCE IN ALKALINE-EARTH DOPED KC1 IRRADIATED AT ROOM TEMPERATURE A. R A S C ~ Nand J. L. ALVAREZ RIVAS Junta de Energia Nuclear, Madrid-3, Spain Abstract. -The thermoluminescence of KC1 : Ca, KC1 : Sr and KC-exponentialfactorsactivationenergiesthat the thermoluminescent processes. It is concluded, as in a previous work on pure Harshaw KC1 crystals

Paris-Sud XI, Université de

74

Albedo neutron dosimetry in Germany: regulations and performance.  

PubMed

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

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

2014-12-01

75

Personnel neutron dosimetry  

SciTech Connect

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

Hankins, D.

1982-04-01

76

TL detectors for gamma ray dose measurements in criticality accidents.  

PubMed

Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Boskovi? Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed. PMID:17369267

Miljani?, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezevi?, Zeljka

2007-01-01

77

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

SciTech Connect

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

Rathbone, Bruce A. (BATTELLE (PACIFIC NW LAB)); McDonald, Joseph C. (BATTELLE (PACIFIC NW LAB)); Traub, Richard J. (BATTELLE (PACIFIC NW LAB))

2002-10-01

78

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

E-print Network

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

Bilski, P; Obryk, B; Hodyr, K

2014-01-01

79

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

80

Microprocessor controlled portable TLD system  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

81

INTERCOMPARISON 2013 ON MEASUREMENTS OF THE PERSONAL DOSE EQUIVALENT Hp(10) IN PHOTON FIELDS IN THE AFRICAN REGION.  

PubMed

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

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

2014-06-30

82

Thermal neutron equivalent dose assessment around the KFUPM neutron source storage area using NTDs. King Fahd University of Petroleum and Minerals.  

PubMed

Area passive neutron dosemeters based on nuclear track detectors (NTDs) have been used for 13 days to assess accumulated low doses of thermal neutrons around neutron source storage area of the King Fahd University of Petroleum and Minerals (KFUPM). Moreover, the aim of this study is to check the effectiveness of shielding of the storage area. NTDs were mounted with the boron converter on their surface as one compressed unit. The converter is a lithium tetraborate (Li2B4O7) layer for thermal neutron detection via 10B(n,alpha)7Li and 6Li(n,alpha)3H nuclear reactions. The area passive dosemeters were installed on 26 different locations around the source storage area and adjacent rooms. The calibration factor for NTD-based area passive neutron dosemeters was found to be 8.3 alpha tracks x cm(-2) x microSv(-1) using active snoopy neutron dosemeters in the KFUPM neutron irradiation facility. The results show the variation of accumulated dose with locations around the storage area. The range of dose rates varied from as low as 40 nSvx h(-1) up to 11 microSv x h(-1). The study indicates that the area passive neutron dosemeter was able to detect accumulated doses as low as 40 nSv x h(-1), which could not be detected with the available active neutron dosemeters. The results of the study also indicate that an additional shielding is required to bring the dose rates down to background level. The present investigation suggests extending this study to find the contribution of doses from fast neutrons around the neutron source storage area using NTDs through proton recoil. The significance of this passive technique is that it is highly sensitive and does not require any electronics or power supplies, as is the case in active systems. PMID:12474945

Abu-Jarad, F; Fazal-ur-Rehman; Al-Haddad, M N; Al-jarallah, M I

2002-01-01

83

Ris-M-2557 HEALTH PHYSICS DEPARTMENT  

E-print Network

14 3 . RADI0EC0LOGY 16 3.1. Environmental radioactivity 16 3.2. Dynamic models of the human food-chain are supplied with the Risø standard beta/gamma personal TLD badge. Additional dosemeters, e.g. fast neutron

84

The use of calcite mineral thermoluminescence for the determination of previously received gamma radiation dose in foodstuffs\\/E1 uso de la termoluminiscencia de la calcita para la determinación de la dosis de radiación gamma de alimentos previamente irradiados  

Microsoft Academic Search

This paper describes the potential use of calcite mineral dust as a high-dose radiation dosemeter. The results obtained show that saturation dose in natural calcite is of the order of 7 kGy. Measurements of absorbed dose, for samples previously irradiated with known gamma doses, showed a good level of agreement between actual doses and calculated doses, although the level of

M. Urbina; P. Beneitez; A. Millán; T. Calderón

1996-01-01

85

Theoretical current response of silicon detectors to fast neutron beams in mixed n, ? fields  

Microsoft Academic Search

A theoretical approach is presented improving the knowledge on real time fast neutron dosimetry in intense fields. The detector is a reverse biased silicon junction operating at room temperature. The signal readout is a current measurement for which the leakage current of the sensor sets the detector threshold in the range of 1Svs?1 dose rates. The dosemeter energy response as

M Jung; C Teissier; P Siffert

1998-01-01

86

' if, --*. u r . f t . ^ ,, f * ^ '  

E-print Network

, tritium, and 60 Co in seawater sediments, sea- plants and mussels in the North Atlantic reg ion 21 #12;Pag 5.1. Chernobyl 37 5.2. Barseback power plant 39 5.3. Argos system 39 l are supplied with the Risø standard beta/gamma personal TLD badge. Additional dosemeters, e.g. fast neutron

87

Electrons in Atoms and Molecules  

NSDL National Science Digital Library

The interactions of electrons with matter have great explanatory power and are central to many technologies from transistors, diodes, smoke detectors, and dosemeters to sophisticated imaging, lasers, and quantum computing. A conceptual grasp of the interactions of electrons in general allows students to acquire deeper understanding that can be applied to a very broad range of technologies.

2012-07-19

88

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

Microsoft Academic Search

This study details the distribution and trends of doses due to occupational radiation exposure among radiation workers from participating medical institutions in Kenya, where monthly dose measurements were collected for a period of one year ranging from January to December in 2007. A total of 367 medical radiation workers were monitored using thermoluminescent dosemeters. They included radiologists (27%), oncologists (2%),

Geoffrey Korir; Jeska Wambani; Ian Korir

2011-01-01

89

Radiation Protection Dosimetry Vol. 100, Nos 14, pp. 207209 (2002)  

E-print Network

on these crystals were studied. Methods of optical absorption, X and UV excited luminescence, thermoluminescence (TL), phototransferred thermoluminescence and optically stimulated luminescence were used in these investigations for radiation detectors and solid state dosemeters. In previous work, mainly thermoluminescence (TL) methods

Chen, Reuven

90

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. PMID:23420859

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

2013-01-01

91

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

92

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.

93

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

94

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

95

A multi-detector neutron spectrometer with nearly isotropic response for environmental and workplace monitoring  

NASA Astrophysics Data System (ADS)

This communication describes an improved design for a neutron spectrometer consisting of 6Li thermoluminescent dosemeters located at selected positions within a single moderating polyethylene sphere. The spatial arrangement of the dosemeters has been designed using the MCNPX Monte Carlo code to calculate the response matrix for 56 log-equidistant energies from 10 -9 to 100 MeV, looking for a configuration that permits to obtain a nearly isotropic response for neutrons in the energy range from thermal to 20 MeV. The feasibility of the proposed spectrometer and the isotropy of its response have been evaluated by simulating exposures to different reference and workplace neutron fields. The FRUIT code has been used for unfolding purposes. The results of the simulations as well as the experimental tests confirm the suitability of the prototype for environmental and workplace monitoring applications.

Gómez-Ros, J. M.; Bedogni, R.; Moraleda, M.; Delgado, A.; Romero, A.; Esposito, A.

2010-01-01

96

Developments in uncertainty analysis for individual monitoring.  

PubMed

Uncertainty analysis is an important part of the quality management programme of an individual monitoring service. Evaluating the uncertainty in measurement is quantifying the quality of measurement. This is emphasised by the recent publication of documents and standards that give guidance on how to perform such an analysis. This paper discusses some aspects of this guidance using a hypothetical dosemeter as an example. It is argued that for personal dosemeters with possibly large uncertainties caused by the energy and angle dependence of the response, the numerical method for the propagation of distributions as described in the Supplement 1 to the 'Guide to the expression of uncertainty in measurement' is the preferred method. PMID:21131658

van Dijk, J W E

2011-03-01

97

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

98

Personal neutron dosimetry in the space station MIR and the Space Shuttle.  

PubMed

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 measurements on the MIR station and in the Space Shuttle flights are presented and the influence of charged particles in the complex mixed radiation field in space is discussed. Improvements are possible by means of a new active neutron dosemeter which is under development at the PTB. First measurements with a prototype in the high-energy reference fields at CERN are presented and discussed. PMID:12025840

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

1999-06-01

99

A whole-body dosimetry system for personal monitoring based on hot-pressed thin layer TLD.  

PubMed

We are introducing a new high-capacity thermoluminescent dosemeter (TLD) system to measure the whole body values of H(p)(10) and H(p)(0.07) from photons for use in individual monitoring services. Small and light-weight badges allow a convenient application in a wide variety of workplaces with photon radiation from 20 keV to at least 7 MeV. The main advantage of this system will be the large capacity of ? 100,000 dosemeters per month at costs equivalent to the current film monitoring. The hot-pressed thin-layer TL detector (LiF:Mg,Ti) is welded onto an aluminium substrate and provided with a data matrix code for automatic processing. The detector holder has been optimised, that no additional filter is necessary. The new designed TLD reader with readout times <10 s will allow a large throughput and a considerable degree of automation. PMID:21227958

Busch, F; Engelhardt, J; Martini, E; Lesz, J

2011-03-01

100

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

PubMed

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

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

2014-10-01

101

The patient as a radioactive source: an intercomparison of survey meters for measurements in nuclear medicine.  

PubMed

In this work, the radiation exposure in nuclear medicine is evaluated by measuring dose rates in the proximity of patients and those in close contact to sources like capsules and syringes. A huge number of different survey meters (SMs) are offered commercially. This topic has recently gained interest since dosemeters and active personal dosemeters (APD) for the new dose quantities (ambient and directional dose equivalent) have become available. One main concern is the practical use of SMs and APD in daily clinical routines. Therefore, the radiation field of four common radiopharmaceuticals containing (18)F, (90)Y, (99m)Tc and (131)I in radioactive sources or after application to the patient was determined. Measurements were carried out with different SMs and for several distances. Dose rates decline significantly with the distance to the patient, and with some restrictions, APD can be used as SMs. PMID:25071244

Uhrhan, K; Drzezga, A; Sudbrock, F

2014-11-01

102

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

103

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

104

Optimum parameters of TLD100 powder used for radiotherapy beams calibration check  

SciTech Connect

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

Arib, M. [Laboratoire Secondaire des Etalons en Dosimetrie, Centre de Recherche Nucleaire d'Alger, Alger Gare (Algeria)]. E-mail: mehenna.arib@comena-dz.org; Yaich, A. [Laboratoire Secondaire des Etalons en Dosimetrie, Centre de Recherche Nucleaire d'Alger, Alger Gare (Algeria); Messadi, A. [Laboratoire Secondaire des Etalons en Dosimetrie, Centre de Recherche Nucleaire d'Alger, Alger Gare (Algeria); Dari, F. [Laboratoire Secondaire des Etalons en Dosimetrie, Centre de Recherche Nucleaire d'Alger, Alger Gare (Algeria)

2006-10-01

105

Monitoring the eye lens: which dose quantity is adequate?  

NASA Astrophysics Data System (ADS)

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

Behrens, R.; Dietze, G.

2010-07-01

106

Monitoring the eye lens: which dose quantity is adequate?  

PubMed

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. The question of which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens arises from this situation. While in many countries dosemeters calibrated in terms of the dose equivalent quantity H(p)(0.07) have been seen as being adequate for monitoring the dose to the eye lens, this might be questionable in the case of reduced dose limits and, thus, it may become necessary to use the dose equivalent quantity H(p)(3) for this purpose. To discuss this question, the dose conversion coefficients for the equivalent dose of the eye lens (in the following eye lens dose) were determined for realistic photon and beta radiation fields and compared with the values of the corresponding conversion coefficients for the different operational quantities. The values obtained lead to the following conclusions: in radiation fields where most of the dose comes from photons, especially x-rays, it is appropriate to use dosemeters calibrated in terms of H(p)(0.07) on a slab phantom, while in other radiation fields (dominated by beta radiation or unknown contributions of photon and beta radiation) dosemeters calibrated in terms of H(p)(3) on a slab phantom should be used. As an alternative, dosemeters calibrated in terms of H(p)(0.07) on a slab phantom could also be used; however, in radiation fields containing beta radiation with the end point energy near 1 MeV, an overestimation of the eye lens dose by up to a factor of 550 is possible. PMID:20601777

Behrens, R; Dietze, G

2010-07-21

107

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

Microsoft Academic Search

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

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

2008-01-01

108

A METHOD TO MINIMISE THE FADING EFFECTS OF LIF:MG,TI (TLD-600 and TLD-700) USING A PRE-HEAT TECHNIQUE.  

PubMed

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

Lee, YoungJu; Won, Yuho; Kang, Kidoo

2014-10-01

109

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

110

Bonner sphere neutron spectrometry at spent fuel casks  

NASA Astrophysics Data System (ADS)

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

Rimpler, Arndt

2002-01-01

111

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

112

Characterisation of OSL and OSLN droplets for dosimetry.  

PubMed

In spite of considerable progress in neutron dosimetry, there is no dosemeter that is capable of measuring neutron doses independently of the neutron spectrum with good accuracy. Carbon-doped aluminium oxide (Al2O3:C) is a sensitive material for ionising radiation (beta-ray, X ray and electron) and has been used for applications in personal and medical dosimetry as an optically stimulated luminescence (OSL) dosemeter. Al2O3:C has a low sensitivity to neutron radiation; this prevents its application to neutron fields, representing a disadvantage of Al2O3:C-OSL when compared with LiF, which is used as a thermoluminescent detector. Recently an improvement for neutron dosimetry (Passmore and Kirr. Neutron response characterisation of an OSL neutron dosemeter. Radiat. Prot. Dosim. 2011; 144: 155-60) uses Al2O3:C coated with (6)Li2CO3 (OSLN),which gives the high-sensitive response as known for Al2O3:C with the advantage of being also sensitive to thermal neutrons. In this article, the authors compare small-size detectors (droplets) of Al2O3:C (OSL) and of Al2O3:C+(6)Li2CO3 (OSLN) and discuss the advantages and drawbacks of both materials, regarding size vs. response. PMID:24381203

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

2014-10-01

113

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

PubMed

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

Cauwels, Vanessa; Vanhavere, Filip; Reginatto, Marcel

2014-10-01

114

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

115

Derivation and application of dose reduction factors for protective eyewear worn in interventional radiology and cardiology.  

PubMed

Doses to the eyes of interventional radiologists and cardiologists could exceed the annual limit of 20?mSv proposed by the International Commission on Radiological Protection. Lead glasses of various designs are available to provide protection, but standard eye dosemeters will not take account of the protection they provide. The aim of this study has been to derive dose reduction factors (DRFs) equal to the ratio of the dose with no eyewear, divided by that when lead glasses are worn. Thirty sets of protective eyewear have been tested in x-ray fields using anthropomorphic phantoms to simulate the patient and clinician in two centres. The experiments performed have determined DRFs from simulations of interventional procedures by measuring doses to the eyes of the phantom representing the clinician, using TLDs in Glasgow, Scotland and with an electronic dosemeter in Gothenburg, Sweden. During interventional procedures scattered x-rays arising from the patient will be incident on the head of the clinician from below and to the side. DRFs for x-rays incident on the front of lead glasses vary from 5.2 to 7.6, while values for orientations similar to those used in the majority of clinical practice are between 1.4 and 5.2. Specialised designs with lead glass side shields or of a wraparound style with angled lenses performed better than lead glasses based on the design of standard spectacles. Results suggest that application of a DRF of 2 would provide a conservative factor that could be applied to personal dosemeter measurements to account for the dose reduction provided by any type of lead glasses provided certain criteria relating to design and consistency of use are applied. PMID:25332300

Magee, Jill S; Martin, Colin J; Sandblom, Viktor; Carter, Matthew J; Almén, Anja; Cederblad, Ake; Jonasson, Pernilla; Lundh, Charlotta

2014-12-01

116

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

PubMed

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

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

2012-11-01

117

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

118

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

119

Dose received by occupationally exposed workers at a nuclear medicine department  

SciTech Connect

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

Avila, O.; Sanchez-Uribe, N. A.; Rodriguez-Laguna, A.; Medina, L. A.; Estrada, E.; Buenfil, A. E.; Brandan, M. E. [Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, DF (Mexico); Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, DF (Mexico) and Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, AP 70-542, 04510, DF (Mexico); Instituto Nacional de Cancerologia (INCan), Av. San Fernando No.22, C.P. 14080 (Mexico); Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, 01000 DF (Mexico) and Unidad de Investigacion Biomedica en Cancer INCan-UNAM, Av. San Fernando No.22 C.P. 4080 (Mexico); Instituto Nacional de Cancerologia (INCan), Av. San Fernando No.22, C.P. 14080 (Mexico); Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364, 01000 DF (Mexico)

2012-10-23

120

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

PubMed Central

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

Gallagher, A; Malone, L; O’Reilly, G

2013-01-01

121

EURADOS trial performance test for neutron personal dosimetry.  

PubMed

This paper reports on the results of a neutron trial performance test sponsored by the European Commission and organised by EURADOS. As anticipated, neutron dosimetry results were very dependent on the dosemeter type and the dose calculation algorithm. Fast neutron fields were generally well measured, but particular problems were noted in the determination of intermediate energy fields and large incident angles, demonstrating the difficulties of neutron personal dosimetry. Of particular concern from a radiological protection point of view was the large number of results underestimating personal dose equivalent. A considerable over-response was noted in a few cases. PMID:11586722

Bordy, J M; Stadtmann, H; Ambrosi, P; Bartlett, D T; Christensen, P; Colgan, T; Hyvönen, H

2001-01-01

122

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

123

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

PubMed

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

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

2014-10-01

124

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

125

Results for NRPB dosimetry services in the 2000 EURADOS trial performance test. National Radiolgical Protection Board. European Radiation Dosimetry Group.  

PubMed

During 2000 a trial performance test for individual monitoring services in Europe was organised by the European Radiation Dosimetry Group (EURADOS), covering whole-body beta/photon, whole-body neutron and extremity beta/photon dosimetry for both monoenergetic and simulated workplace fields. The UK National Radiological Protection Board (NRPB), which supplies routine dosemeters to some 50,000 wearers in the UK and overseas, participated in this trial performance test. This paper presents the results obtained for the NRPB whole-body TLD, neutron (PADC) and extremity dosimetry services and comments on their performance in comparison with the overall results. PMID:12382744

Gilvin, P J; Dunderdale, J; Perkins, D K

2002-01-01

126

Investigation about the thermal features of the ovens used for thermoluminescence  

E-print Network

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

Scarpa, G; Moscati, M

1991-01-01

127

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

128

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

129

Characterization of neutron reference fields at US Department of Energy calibration fields.  

PubMed

The Health Physics Measurements Group at the Los Alamos National Laboratory (LANL) has initiated a study of neutron reference fields at selected US Department of Energy (DOE) calibration facilities. To date, field characterisation has been completed at five facilities. These fields are traceable to the National Institute for Standards and Technology (NIST) through either a primary calibration of the source emission rate or through the use of a secondary standard. However, neutron spectral variation is caused by factors such as room return, scatter from positioning tables and fixtures, source anisotropy and spectral degradation due to source rabbits and guide tubes. Perturbations from the ideal isotropic point source field may impact the accuracy of instrument calibrations. In particular, the thermal neutron component of the spectrum, while contributing only a small fraction of the conventionally true dose, can contribute a significant fraction of a dosemeter's response with the result that the calibration becomes facility-specific. A protocol has been developed to characterise neutron fields that relies primarily on spectral measurements with the Bubble Technology Industries (BTI) rotating neutron spectrometer (ROSPEC) and the LANL Bonner sphere spectrometer. The ROSPEC measurements were supplemented at several sites by the BTI Simple Scintillation Spectrometer probe, which is designed to extend the ROSPEC upper energy range from 5 to 15 MeV. In addition, measurements were performed with several rem meters and neutron dosemeters. Detailed simulations were performed using the LANL MCNPX Monte Carlo code to calculate the magnitude of source anisotropy and scatter factors. PMID:17496290

Olsher, R H; McLean, T D; Mallett, M W; Seagraves, D T; Gadd, M S; Markham, Robin L; Murphy, R O; Devine, R T

2007-01-01

130

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

PubMed

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

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

2011-03-01

131

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

132

Verification of an effective dose equivalent model for neutrons  

NASA Astrophysics Data System (ADS)

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 D2O-moderated Cf-252 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.

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

1991-10-01

133

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

134

Eye dosimetry in interventional radiology and cardiology: current challenges and practical considerations.  

PubMed

Interventional radiology and cardiology are areas with high potential for risk to eye lens. Accurate assessment of eye dose is one of the most important aspects of correlating doses with observed lens opacities among workers in interventional suites and ascertaining compliance with regulatory limits. The purpose of this paper is to review current approaches and opportunities in eye dosimetry and assess challenges in particular in accuracy and practicality. The possible approaches include practical dosimetry using passive dosemeters or active dosemeters with obvious advantage of active dosimetry. When neither of these is available, other approaches are based on either retrospective dose assessment using scatter radiation dose levels or correlations between patient dose indices and eye doses to the operators. In spite of all uncertainties and variations, estimation of eye dose from patient dose can be accepted as a compromise. Future challenges include development of practical methods for regular monitoring of individual eye doses and development of better techniques to estimate eye dose from measurements at some reference points. PMID:24262928

Ciraj-Bjelac, O; Rehani, M M

2014-12-01

135

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

136

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

PubMed Central

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

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

2013-01-01

137

Intercomparison of radiation protection instrumentation in a pulsed neutron field  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

138

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

PubMed

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

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

2015-02-01

139

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

140

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

SciTech Connect

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

Quam, W.; DeVore, T.

1984-06-01

141

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

SciTech Connect

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

Mark E. Kubiske

2013-04-15

142

Interim status report of the TMI personnel-dosimetry project  

SciTech Connect

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

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

1981-06-01

143

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

PubMed

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

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

2006-01-01

144

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

PubMed

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

Liu, Huiliang; Jin, Zhigeng; Jing, Limin

2014-03-01

145

Intercomparison of dosimetry systems based on CaF2:Mn TL detectors.  

PubMed

The responses of readings by the TL dosimetry system MR200 TL developed in-house and used at JSI and the TOLEDO TL system used at RBI are compared. Ten measurements at different doses ranging from 0.01 mSv to 5 Sv were carried out. A set of 36 dosemeters with three pellets of CaF2:Mn were irradiated in radiation fields of 137Cs and 60Co. Analysis of the measured results shows that at doses below 0.1 Sv, readers' outputs do not differ >5% from each other. At doses >1 Sv, the results obtained by the MR200 reader must be corrected with a known factor. Finally, the reproducibility of the results from the MR200 was tested. PMID:16735564

Zorko, B; Miljani?, S; Veki?, B; Stuhec, M; Gobec, S; Ranogajec-Komor, M

2006-01-01

146

A phantom-based evaluation of three commercially available patient organ shields for computed tomography X-ray examinations in diagnostic radiology.  

PubMed

Three commercially available in-plane patient organ shields (barium eye, bismuth eye and bismuth breast) for computed tomography (CT) examinations were evaluated to determine their effectiveness for dose reduction. Absorbed doses were measured using metal oxide semiconductor field effect transistor dosemeters fastened to a Kyoto CT Torso phantom. Resultant images were visually compared with those minus shielding by an experienced radiologist. Approximate dose reductions of 21, 38 and 50 % were achieved by the barium eye, bismuth eye and bismuth breast shields, respectively, at a cost of increased image noise and streak artefacts. Shielded images produced varied levels of image artefact, particularly those resulting from the eye shields. Measured dose reductions were not consistent with the potential dose savings stated by the manufacturers of the shields. When evaluating the breast shield, similar dose reduction was achieved without shield-induced artefact by simply reducing the X-ray tube current. PMID:23222552

Huggett, Jamie; Mukonoweshuro, William; Loader, Robert

2013-07-01

147

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

PubMed

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

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

2014-10-01

148

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

149

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

PubMed

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

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

2014-10-01

150

Organ dose evaluation for multi-slice spiral CT scans based on China Sichuan chest anthropomorphic phantom measurements.  

PubMed

The authors measured organ radiation doses during multi-slice computed tomography (MSCT) chest scans using a China Sichuan anthropomorphic phantom (CDP-1C). Chest CT images from live volunteers based on automatic tube current modulation (ATCM) techniques were similar to those obtained using the CDP-1C phantom, indicating that the phantom accurately modelled the anatomic structure and X-ray absorbance of the human torso. Indeed, attenuation values differed by <5%. Organ radiation doses were measured using thermoluminescence dosemeters in the CDP-1C. With increased noise index, the CT dose index, the dose-length product and the average organ dose all decreased. Thus, the CDP-1C phantom can also assess dose levels during CT examinations in Chinese patients. The noise index (based on ATCM techniques) should be set to 8.5 or higher to reduce X-ray exposure while maintaining appropriate resolution for diagnosis. PMID:22039271

Peng, Gang; Zeng, Yongming; Luo, Tianyou; Zhao, Feng; Peng, Shengkun; You, Renqiang; Tan, Hua; Liu, Xiao; Wang, Jie

2012-07-01

151

Review of retrospective dosimetry techniques for external ionising radiation exposures.  

PubMed

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

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

2011-11-01

152

Indoor radon levels in schools of South-East Italy.  

PubMed

A survey was conducted to evaluate average levels of indoor radon and gamma doses in all educational buildings (506 schools) located in South-East Italy (the Salento peninsula, province of Lecce). In this paper the final findings relating to measurements performed with SSNTD dosemeters in 438 schools (86% of the sample) are reported. The average annual activity concentration of radon in schools located in the province of Lecce is 209 ± 9 Bq/m(3). Radon values actually ranged from 21 Bq/m(3) to 1608 Bq/m(3). About 7% of schools showed radon concentration values above 500 Bq/m(3), the Italian action level for workplaces. PMID:22789472

Trevisi, Rosabianca; Leonardi, Federica; Simeoni, Carla; Tonnarini, Sabrina; Veschetti, Miriam

2012-10-01

153

Thermal neutron calibration channel at LNMRI/IRD.  

PubMed

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

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

2014-10-01

154

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

PubMed Central

The objective of this study was to evaluate the organ dose and effective dose to patients undergoing routine adult and paediatric CT examinations with 64-slice CT scanners and to compare the doses with those from 4-, 8- and 16-multislice CT scanners. Patient doses were measured with small (<7 mm wide) silicon photodiode dosemeters (34 in total), which were implanted at various tissue and organ positions within adult and 6-year-old child anthropomorphic phantoms. Output signals from photodiode dosemeters were read on a personal computer, from which organ and effective doses were computed. For the adult phantom, organ doses (for organs within the scan range) and effective doses were 8–35 mGy and 7–18 mSv, respectively, for chest CT, and 12–33 mGy and 10–21 mSv, respectively, for abdominopelvic CT. For the paediatric phantom, organ and effective doses were 4–17 mGy and 3–7 mSv, respectively, for chest CT, and 5–14 mGy and 3–9 mSv, respectively, for abdominopelvic CT. Doses to organs at the boundaries of the scan length were higher for 64-slice CT scanners using large beam widths and/or a large pitch because of the larger extent of over-ranging. The CT dose index (CTDIvol), dose–length product (DLP) and the effective dose values using 64-slice CT for the adult and paediatric phantoms were the same as those obtained using 4-, 8- and 16-slice CT. Conversion factors of DLP to the effective dose by International Commission on Radiological Protection 103 were 0.024 mSv?mGy?1?cm?1 and 0.019 mSv?mGy?1?cm?1 for adult chest and abdominopelvic CT scans, respectively. PMID:19934069

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

2009-01-01

155

The use of LiF (TLD-100) as an out-of-field dosimeter.  

PubMed

The commonly used thermoluminescent dosimeter TLD-100 (Harshaw Chemical Company, Solon, OH) responds not only to photons and electrons, but also to neutrons that are produced during high-energy therapies. As a result, TLD-100 measurements outside of the treatment field are suspect when high-energy radiation is used. Although alternatives such as TLD-700 do not respond to neutrons, specialty dosimeters of this kind are expensive and are not routinely used in most clinics. In the current study, we examined the accuracy of TLD-100 in measuring the out-of-field photon dose as a function of treatment energy. To determine the accuracy of TLD-100 as compared with TLD-700, TLD-100 was irradiated outside of the treatment field by medical accelerators operated at 6, 10, 15, and 18 MV. In an effort to eliminate the response of TLD-100 to neutrons, TLD capsules were encased in varying thicknesses of cadmium foil (0.25 - 0.75 mm) before being irradiated at 18 MV. The out-of-field TLD-100 was found to be accurate at 6 MV and 10 MV, but to be substantially over-responsive at 15 MV and 18 MV (by up to 1063% relative to TLD-700). By wrapping the TLD-100 in up to 0.75 mm of cadmium, it was possible to drastically reduce (down to 39% on average) the over-response of the TLD-100; however, total removal of the over-responsiveness was not possible. Although TLD-100 is well suited for measuring out-of-field dose at energies as high as 10 MV, at higher energies (15 MV or greater), this dosimeter over-responds substantially and should not be used. Although encasing the TLD in cadmium minimized over-response to a degree, the reduction was not sufficient to make TLD-100 viable for measuring out-of-field dose at high treatment energies. PMID:18449155

Kry, Stephen F; Price, Michael; Followill, David; Mourtada, Firas; Salehpour, Mohammad

2007-01-01

156

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

157

Personal dose equivalent conversion coefficients for photons to 1 GeV.  

PubMed

The personal dose equivalent, H(p)(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity effective dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk, where personal dosemeters are usually worn, and in this instance a suitable approximation is a 30 × 30 × 15 cm(3) slab-type phantom. For this condition, the personal dose equivalent is denoted as H(p,slab)(d) and the depths, d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several megaelectronvolts, however, data to higher energies are limited. In this work, conversion coefficients up to 1 GeV have been calculated for H(p,slab)(10) and H(p,slab)(3) both by using the kerma approximation and tracking secondary charged particles. For H(p)(0.07), the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H(p,slab)(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom, conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared with the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance. PMID:21148165

Veinot, K G; Hertel, N E

2011-04-01

158

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

159

The Development, Characterization, and Performance Evaluation of a New Combination Type Personnel Neutron Dosimeter  

NASA Astrophysics Data System (ADS)

A new combination type personnel neutron dosimeter has been designed and developed at the Oak Ridge National Laboratory (ORNL). The combination personnel neutron dosimeter (CPND) consists of a Harshaw albedo neutron thermoluminescent dosimeter (two pairs of TLD-600/TLD-700) and two bubble detectors (one BD-100R and one BDS-1500 from Bubble Technology Industries, Canada). The CPND was developed with the aim of having crude neutron spectrometric capability, universal applicability, better angular response, and an improved lower limit of detection (LLD). The CPND has been well characterized in the following areas: reusability, linearity, lower limit of detection (LLD), detection capability in mixed neutron-gamma fields, angular dependence, and neutron energy dependence. The characterization was accomplished with irradiations using a ^{238} Pu-Be source, a ^{252} Cf(D_2O) source, a ^{252}Cf source, a ^ {252}Cf(PE) source, monoenergetic neutrons from accelerator and reactor filtered beams, ^ {137}Cs, and X-rays. Optimum signal readout procedures, signal processing techniques, routine operational usage, and neutron dose equivalent evaluation algorithms for the CPND were developed with the goals of having the best precision and accuracy as well as being convenient to use. Various reference spectra were developed to evaluate the performance (mainly the spectrometric and the dose equivalent measurement capabilities) of the CPND. The performance of the CPND was evaluated by in-situ tests in radiation fields existing in the working environment at ORNL. The spectra in these areas were measured previously with a calibrated Bonner multisphere spectrometer. The CPND also was tested with laboratory radioisotopic sources in single-source and multi-source exposure situations. Finally, the CPND was tested by participating in the fourteenth Personnel Dosimetry Intercomparison Study. The results of the tests mentioned above demonstrated that the CPND meets the ambitious design purposes. Because of its 4 -interval spectrometric capability and high sensitivity, the CPND can be used, without prior knowledge of the spectrum or calibration in the field, to provide accurate dose equivalent estimates. The results of the detailed characterization and performance tests showed that the new CPND is an excellent personnel neutron dosimeter.

Liu, Chwei-Jeng

160

Regional geochemical studies in the Patagonia Mountains, Santa Cruz County, Arizona  

USGS Publications Warehouse

The Patagonia Mountains in southern Arizona contain the deeply buried porphyry copper system at Red Mountain as well as a number of other base- and precious-metal mines and prospects. The range contains complex Basin and Range geology with units ranging in age from Precambrian to Holocene. Rock types present include igneous intrusive and extrusive units as well as sedimentary and metamorphic units, most of which have been tectonically disturbed. A total of 264 stream-sediment samples were collected and analyzed for 32 elements. Geochemical maps for Sb, Ag, Pb, Te, B, Mn, Au, Zn, Cu (total), Cu (cold-extractable), and Mo, as well as for Cu (cold-extractable)/Cu (total) and Fe/Mn, are presented. Anomaly patterns for these elements generally occur over the Red Mountain deposit and (or) along a north-northwest trend parallel to the major Harshaw Creek Fault. Much of the entire area sampled contains widespread anomalies for Pb, Te, and Cu; the other elements are only locally anomalous. Various plots of ratios of Cu (cold-extractable) to Cu (total) did not produce any new information not readily apparent on either one of the two copper maps. A plot of ratios of Fe to Mn delineated many areas of pyrite mineralization. Several of these areas may represent the pyritic halos around deeply buried porphyry copper systems. The best ore guide for the Red Mountain porphyry system is the coincidence of positive anomalies of Mo, Pb, and Te and a negative anomaly of Mn. Other areas with anomalies of the same suite of elements are present within the Patagonia Mountains. It is concluded that geochemical sampling, even in a highly contaminated area, can be useful in delineating major geologic features, such as porphyry copper belts and major faults. Multielement geochemical surveys on a regional scale can effectively locate large, deeply buried, zoned mineral systems such as that at Red Mountain. Plots of element ratios, where adequately understood, can provide geochemical information not readily discernible from plots of single elements alone. ?? 1981.

Chaffee, M.A.; Hill, R.H.; Sutley, S.J.; Watterson, J.R.

1981-01-01

161

Personal dose equivalent conversion coefficients for electrons to 1 Ge V.  

PubMed

In a previous paper, conversion coefficients for the personal dose equivalent, H(p)(d), for photons were reported. This note reports values for electrons calculated using similar techniques. The personal dose equivalent is the quantity used to approximate the protection quantity effective dose when performing personal dosemeter calibrations and in practice the personal dose equivalent is determined using a 30×30×15 cm slab-type phantom. Conversion coefficients to 1 GeV have been calculated for H(p)(10), H(p)(3) and H(p)(0.07) in the recommended slab phantom. Although the conversion coefficients were determined for discrete incident energies, analytical fits of the conversion coefficients over the energy range are provided using a similar formulation as in the photon results previously reported. The conversion coefficients for the personal dose equivalent are compared with the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection guidance. Effects of eyewear on H(p)(3) are also discussed. PMID:21715410

Veinot, K G; Hertel, N E

2012-04-01

162

SAMARIUM-153 THERAPY FOR PROSTATE CANCER: THE EVALUATION OF URINE ACTIVITY, STAFF EXPOSURE AND DOSE RATE FROM PATIENTS.  

PubMed

The aim of this study was to determine the excretion of Samarium-153-ethylenediaminetetramethylphosphonic acid ((153)Sm-EDTMP) in urine and to calculate the dose rate of its retention in the body as a function of time and the dose received by the skin of laboratory staff's finger. Urine samples were collected from 11 patients after intravenous injection of (153)Sm-EDTMP. The measurements of dose rate were performed. Thermoluminescent dosemeters were used for absorbed dose measurements. Effective half-lives that were calculated from urine sample measurements were found as 7.1±3 h within the first 24 h. Whole body dose rates before collecting urine of patients were 60.0 ± 15.7 µSv h(-1) for within 1 h following (153)Sm-EDTMP administration. The highest finger radiation dose is to the right-hand thumb (3.8 ± 2 mGy). The results of the study imply that patients who recieved (153)Sm-EDTMP therapy should be kept a minumum of 8 h in an isolated room at hospital and that one staff should give therapy at most two patients per week. PMID:25063786

Parlak, Yasemin; Gumuser, Gul; Sayit, Elvan

2014-07-25

163

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. PMID:22972973

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

2012-01-01

164

Comparison of organ dosimetry methods and effective dose calculation methods for paediatric CT.  

PubMed

Computed tomography (CT) is the single biggest ionising radiation risk from anthropogenic exposure. Reducing unnecessary carcinogenic risks from this source requires the determination of organ and tissue absorbed doses to estimate detrimental stochastic effects. In addition, effective dose can be used to assess comparative risk between exposure situations and facilitate dose reduction through optimisation. Children are at the highest risk from radiation induced carcinogenesis and therefore dosimetry for paediatric CT recipients is essential in addressing the ionising radiation health risks of CT scanning. However, there is no well-defined method in the clinical environment for routinely and reliably performing paediatric CT organ dosimetry and there are numerous methods utilised for estimating paediatric CT effective dose. Therefore, in this study, eleven computational methods for organ dosimetry and/or effective dose calculation were investigated and compared with absorbed doses measured using thermoluminescent dosemeters placed in a physical anthropomorphic phantom representing a 10 year old child. Three common clinical paediatric CT protocols including brain, chest and abdomen/pelvis examinations were evaluated. Overall, computed absorbed doses to organs and tissues fully and directly irradiated demonstrated better agreement (within approximately 50 %) with the measured absorbed doses than absorbed doses to distributed organs or to those located on the periphery of the scan volume, which showed up to a 15-fold dose variation. The disparities predominantly arose from differences in the phantoms used. While the ability to estimate CT dose is essential for risk assessment and radiation protection, identifying a simple, practical dosimetry method remains challenging. PMID:22492218

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

2012-06-01

165

Natural radiation exposure in a municipality of the Brazilian Sertao  

SciTech Connect

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

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

1996-08-01

166

Effective dose span of ten different cone beam CT devices  

PubMed Central

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

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

2013-01-01

167

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

168

Neural network modelling of dose distribution and dose uniformity in the Tunisian Gamma Irradiator.  

PubMed

In this paper an approach to model dose distributions, isodose curves and dose uniformity in the Tunisian Gamma Irradiation Facility using artificial neural networks (ANNs) are described. For this purpose, measurements were carried out at different points in the irradiation cell using polymethyl methacrylate dosemeters. The calculated and experimental results are compared and good agreement is observed showing that ANNs can be used as an efficient tool for modelling dose distribution in the gamma irradiation facility. Monte Carlo (MC) photon-transport simulation techniques have been used to evaluate the spatial dose distribution for extensive benchmarking. ANN approach appears to be a significant advance over the time-consuming MC or the less accurate regression methods for dose mapping. As a second application, a detailed dose mapping using two different product densities was carried out. The minimum and maximum dose locations and dose uniformity as a function of the irradiated volume for each product density were determined. Good agreement between ANN modelling and experimental results was achieved. PMID:23633649

Manai, K; Trabelsi, A

2013-11-01

169

Indoor radon levels in urban Hyderabad area, Andhra Pradesh, India.  

PubMed

Indoor radon levels in urban areas of Hyderabad, Andhra Pradesh, India were measured by a time integrated method using solid state nuclear track detector-based dosemeters. Results show that the radon levels varied widely in the area ranging from 17 to 311 Bq m(-3) with a geometric mean value of 52.8 Bq m(-3) (GSD=1.7). Cumulative frequency distribution of radon levels gave a best fit on a log-normal scale. Measurements were carried out for 1 y, segregating the measurement periods in accordance with seasonal changes. Soil samples from the region were also analysed for natural radionuclides to study its effect, if any, on indoor radon levels. Dwellings categorised based on construction types showed that the average radon levels in the order tiles (TLE)>asbestos (ASB)>concrete (RCC) for the roof structures. The estimated radon levels in the study area are relatively higher than the country's average value of 23 Bq m(-3) and global average value of 30 Bq m(-3). PMID:19122001

Sreenath Reddy, M; Yadagiri Reddy, P; Rama Reddy, K; Eappen, K P; Ramachandran, T V; Mayya, Y S

2008-01-01

170

EVALUATION OF DOSE FROM EXTERNAL IRRADIATION FOR INDIVIDUALS LIVING IN AREAS AFFECTED BY THE FUKUSHIMA DAIICHI NUCLEAR PLANT ACCIDENT.  

PubMed

In order to effectively and appropriately manage external radiation doses in the affected areas of Fukushima, it is important to identify when, where and how much exposure occurred. It is also necessary to quantitatively measure external exposure and air dose rates for different activity patterns in individuals living and working in Japanese-style buildings. The authors used a new personal dosemeter (D-shuttle) along with a global positioning system and geographical information system to relate personal dose rate with activity patterns and air dose rate. Hourly individual doses obtained by D-shuttle can provide an effective communication tool for those who want to identify when and how much exposure occurs. Personal monitoring of 26 volunteers showed that personal doses obtained from D-shuttle were ?30 % of cumulative air dose estimated by data from the airborne monitoring survey. This analysis showed that, for most study volunteers, the exposure from staying at home represented about half of the total cumulative dose. This suggests that even though the peak exposure doses may be observed outside of working hours, to develop appropriate countermeasures for external dose reduction, it is thus important to identify the contributions of individuals' time-activities. This study provides a valuable basis for developing a realistic and pragmatic method to estimate external doses of individuals in Fukushima. PMID:24982262

Naito, Wataru; Uesaka, Motoki; Yamada, Chie; Ishii, Hideki

2014-06-30

171

Estimation of radiation dose at various depths for commonly used radionuclides in radiosynoviorthesis in a tissue equivalent material.  

PubMed

The purpose of the paper is to report on the dose estimation studies at various depths for the commonly used beta-emitting 90Y, 166Ho, 153Sm, 32p, and 177Lu radionuclides in a phantom fabricated using the poly methyl methacrylate tissue equivalent material having a density of 1.19 gm/cc, by using thermoluminescent dosemeters. GAFChromic MD-55 films were used to calculate the calibration factor for the thermoluminescent micro-rods used in our study. It is observed that 90Y delivers the highest dose at 1 mm amongst the radionuclides tested followed by 32p, 166Ho, 153Sm, and 177Lu, whereas the cumulative dose received by the joint was found to be more for 32P followed by 90Y, 166Ho, 153Sm, and 177Lu. The highest therapeutic range obtained is 3.1 mm for 153Sm amongst the tested radionuclides. The dose values obtained for all the above-mentioned radionuclides can serve as reference material for those researchers and clinicians who are interested in selection of the radionuclide for the type of joint treated and the amount of dose necessary to be delivered to the synovial membrane. PMID:16964849

Tandon, Pankaj; Malpani, B L; Venkatesh, Meera; Bhatt, B C

2006-08-01

172

A study of environmental radioactivity measurements in the Samsun province, Turkey.  

PubMed

This study was concerned with the measurement of natural and artificial radionuclides in soil samples and indoor radon concentrations in the Samsun province, Turkey. In soil samples, the values of individual mean activity of (226)Ra, (232)Th, (40)K and (137)Cs radionuclides were found to be 31, 22, 341 and 16 Bq kg(-1), respectively. The radiological parameters, such as the absorbed dose rate in air, the annual effective dose (AED) and excess lifetime cancer risk, were calculated. Indoor radon measurements were carried out with CR-39-based radon dosemeters at 127 dwellings in the Samsun province. The mean annual (222)Rn activity was found to be 106 Bq m(-3) (equivalent to an AED of 1.88 mSv). The seasonal variation of (222)Rn activity shows that maximum levels are observed in the winter, while minimum levels are observed in the summer. The mean lifetime fatality risk for the studied area was estimated at 1.45×10(-4). The results obtained did not significantly differ from those obtained in other parts of the country. PMID:22619352

Kucukomeroglu, B; Maksutoglu, F; Damla, N; Cevik, U; Celebi, N

2012-12-01

173

MONITORING THE EYE LENS: HOW DO THE INTERNATIONAL ORGANISATIONS REACT?  

PubMed

The International Commission on Radiological Protection (ICRP) has recommended to lower the limit of the dose to the eye lens for occupationally exposed persons to a mean value of 20 mSv y(-1) (averaged over 5 y, with a maximum of 50 mSv y(-1)); already in the autumn of 2011, both the European Commission and the International Atomic Energy Agency : IAEA) took over this reduction in their respective draft basic safety standards. Even prior to this (and since then, increasingly so), several international activities were started (among other things, the following ones): (1) the ICRP adopted a stylised model of the eye to calculate dose conversion coefficients for its report ICRP 116; (2) the European Commission has funded the ORAMED project dealing with radiation protection in medicine; (3) in its standard IEC 62387 on passive dosimetry systems, the International Electrotechnical Commission (IEC) has laid down requirements for Hp(3) eye dosemeters; (4) the International Organization for Standardization (ISO) and the IAEA provide a range of practical advice in the standard ISO 15382 (still a draft) and in a technical document IAEA TecDoc on both radiation protection and on dosimetry; (5) for most cases, the International Commission on Radiation Units and Measurements (ICRU) recommends both phantoms (the slab and the cylinder). In short: most national procedures can orientate themselves on international ones; some questions, however, remain open. PMID:25213264

Behrens, R

2014-09-11

174

Dose reduction of cone beam CT scanning for the entire oral and maxillofacial regions with thyroid collars  

PubMed Central

Objective The aim of this study was to evaluate the influence of thyroid collars on radiation dose during cone beam CT (CBCT) scanning. Methods Average tissue-absorbed dose for a NewTom 9000 CBCT scanner (Quantitative Radiology, Verona, Italy) was measured using thermoluminescent dosemeter chips in a phantom. The scans were carried out with and without thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection 2007 recommendations. Results The effective organ doses for the thyroid gland and oesophagus were 31.0 µSv and 2.4 µSv, respectively, during CBCT scanning without a collar around the neck. When the thyroid collars were used loosely around the neck, no effective organ dose reduction was observed. When one thyroid collar was used tightly on the front of the neck, the effective organ dose for the thyroid gland and oesophagus were reduced to 15.9 µSv (48.7% reduction) and 1.4 µSv (41.7% reduction), respectively. Similar organ dose reduction (46.5% and 41.7%) was achieved when CBCT scanning was performed with two collars tightly on the front and back of the neck. However, the differences to the total effective dose were not significant among the scans with and without collars around the neck (p = 0.775). Conclusions Thyroid collars can effectively reduce the radiation dose to the thyroid and oesophagus if used appropriately. PMID:22707330

Qu, XM; Li, G; Sanderink, GCH; Zhang, ZY; Ma, XC

2012-01-01

175

Thermoluminescence characteristics of teflon embedded CaSO4:Dy TLD.  

PubMed

The Korea Atomic Energy Research Institute (KAERI) is manufacturing CaSO4:Dy Teflon TL pellets which have more sensitivity and stability than commercial TLD. A method is presented of preparing the CaSO4:Dy phosphor-embedded Teflon powder, which is then compressed to a thin pellet form used as the TLD element. Investigations are made to determine optimum preparation conditions and dosimetric characteristics of the CaSO4:Dy Teflon pellet such as the sensitivity, energy response, dose response, fading, re-usability, and lowest level of detection. The results show that the sensitivity of the CaSO4:Dy pellet is 2 times higher than that of the commercial Teledyne CaSO4:Dy pellet. A dose-response was observed to be linear in the range from 10(-5) to 10 Gy. The relative energy response in the low energy region was 9.6 (normalised to the 137Cs gamma source), and the fading rate was about 10% for five months. The re-usability was estimated to be more than 60 cycles, and the low level of detection dose was 22 microGy. From the results, the CaSO4:Dy pellet developed in KAERI can be successfully used in personal dosemeters through appropriate filter design for compensating the energy response. PMID:12382892

Yang, J S; Kim, D Y; Kim, J L; Chang, S Y; Nam, Y M; Park, J W

2002-01-01

176

Measurement of potential alpha energy exposure and potential alpha energy concentration and estimating radiation dose of radon in Sari city in the north region of Iran.  

PubMed

In dwellings in Sari city in the northern region of Iran, the potential alpha energy exposure (PAEE) and potential alpha energy concentration (PAEC) have been measured and the radiation dose due to radon and its progenies has been estimated. In this study, the dosemeters DOSEman and SARAD GmbH (Germany), which are sensitive to alpha particles, were used. The population of the city of Sari is 495 369 people and the density of population is 116.5 people per km(2). A percentage of the total household population of Sari in areas of geographically different samples was selected. The PAEE, PAEC and radon concentration in four different seasons in a year in homes for sampling were measured. The mean PAEE due to indoor radon in homes of four cities in Sari city was estimated to be 28.23 Bq m(-3) and the mean PAEC was estimated to be 27.11 Bq m(-3). Also the mean indoor radon level was found to be 29.95 Bq m(-3). The annual dose equivalent is ?0.0151 ?Sv y(-1). Measurement results show that the average PAEE, PAEC and radon concentration are higher in winter than in other seasons. This difference could be due to stillness and lack of air movement indoors in winter. PMID:24292487

Rahimi, Seyed Ali; Nikpour, Behzad

2014-12-01

177

Bubble-detector measurements in the Russian segment of the International Space Station during 2009-12.  

PubMed

Measurements using bubble detectors have been performed in order to characterise the neutron dose and energy spectrum in the Russian segment of the International Space Station (ISS). Experiments using bubble dosemeters and a bubble-detector spectrometer, a set of six detectors with different energy thresholds that is used to determine the neutron spectrum, were performed during the ISS-22 (2009) to ISS-33 (2012) missions. The spectrometric measurements are in good agreement with earlier data, exhibiting expected features of the neutron energy spectrum in space. Experiments using a hydrogenous radiation shield show that the neutron dose can be reduced by shielding, with a reduction similar to that determined in earlier measurements using bubble detectors. The bubble-detector data are compared with measurements performed on the ISS using other instruments and are correlated with potential influencing factors such as the ISS altitude and the solar activity. Surprisingly, these influences do not seem to have a strong effect on the neutron dose or energy spectrum inside the ISS. PMID:24714114

Smith, M B; Khulapko, S; Andrews, H R; Arkhangelsky, V; Ing, H; Lewis, B J; Machrafi, R; Nikolaev, I; Shurshakov, V

2015-01-01

178

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

PubMed

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

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

2014-10-01

179

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

PubMed

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

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

2005-01-01

180

Radiation-induced chromosome damage in human lymphocytes  

PubMed Central

ABSTRACT Analysis for chromosome aberrations in human peripheral blood lymphocytes has been developed as an indicator of dose from ionising radiation. This paper outlines the mechanism of production of aberrations, the technique for their analysis and the dose-effect relationships for various types of radiation. During the past ten years the National Radiological Protection Board has developed a service for the UK in which estimates of dose from chromosome aberration analysis are made on people known or suspected of being accidentally over-exposed. This service can provide estimates where no physical dosemeter was worn and is frequently able to resolve anomalous or disputed data from routine film badges. Several problems in the interpretation of chromosome aberration yields are reviewed. These include the effects of partial body irradiation and the response to variations in dose rate and the intermittent nature of some exposures. The dosimetry service is supported by a research programme which includes surveys of groups of patients irradiated for medical purposes. Two surveys are described. In the first, lymphocyte aberrations were examined in rheumatiod arthritis patients receiving intra-articular injections of colloidal radiogold or radioyttrium. A proportion of the nuclide leaked from the joint into the regional lymphatic system. In the second survey a comparison was made between the cytogenetic and physical estimates of whole body dose in patients receiving iodine 131 for thyroid carcinoma. Images PMID:338021

Lloyd, D. C.; Dolphin, G. W.

1977-01-01

181

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

182

The effects of high ambient radon on thermoluminescence dosimetry readings.  

PubMed

The effect of a high level of ambient (222)Rn gas on thermoluminescence dosemeters (TLDs) is examined. Groups of LiF:Mg,Ti and CaF(2):Dy TLDs were exposed to (222)Rn under controlled environmental conditions over ?7 d using a luminous (226)Ra aircraft dial. LiF:Mg,Ti TLDs were tested bare, and both types were tested mounted in cards used for environmental dosimetry and mounted in cards enclosed in plastic badges. A passive continuous radon monitor was used to measure the (222)Rn level in the small chamber during the experiments. The data were analysed to determine the relationship between the integrated (222)Rn level and the TLD response. Although both LiF:Mg,Ti and CaF(2):Dy TLDs showed a strong response to (222)Rn, the badges prevented measurable radon detection by the TLDs within. The TLDs were not used to directly measure the radon concentration; rather, a correction for its influence was desired. PMID:21177272

Harvey, John A; Kearfott, Kimberlee J

2011-11-01

183

Estimation of radiation dose at various depths for commonly used radionuclides in radiosynoviorthesis in a tissue equivalent material  

SciTech Connect

The purpose of the paper is to report on the dose estimation studies at various depths for the commonly used beta-emitting {sup 90}Y, {sup 166}Ho, {sup 153}Sm, {sup 32}P, and {sup 177}Lu radionuclides in a phantom fabricated using the poly methyl methacrylate tissue equivalent material having a density of 1.19 gm/cc, by using thermoluminescent dosemeters. GAFChromic MD-55 films were used to calculate the calibration factor for the thermoluminescent micro-rods used in our study. It is observed that {sup 90}Y delivers the highest dose at 1 mm amongst the radionuclides tested followed by {sup 32}P, {sup 166}Ho, {sup 153}Sm, and {sup 177}Lu, whereas the cumulative dose received by the joint was found to be more for {sup 32}P followed by {sup 90}Y, {sup 166}Ho, {sup 153}Sm, and {sup 177}Lu. The highest therapeutic range obtained is 3.1 mm for {sup 153}Sm amongst the tested radionuclides. The dose values obtained for all the above-mentioned radionuclides can serve as reference material for those researchers and clinicians who are interested in selection of the radionuclide for the type of joint treated and the amount of dose necessary to be delivered to the synovial membrane.

Tandon, Pankaj; Malpani, B. L.; Venkatesh, Meera; Bhatt, B. C. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, CT and CRS Building, Anushaktinagar, Mumbai, 400 094 (India); Radiation Medicine Centre, Bhabha Atomic Research Centre, CT and CRS Building, Anushaktinagar, Mumbai, 400 094 (India); Radiopharmaceutical Division, Bhabha Atomic Research Centre, CT and CRS Building, Anushaktinagar, Mumbai, 400 094 (India); Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, CT and CRS Building, Anushaktinagar, Mumbai, 400 094 (India)

2006-08-15

184

A study on the radiation dose of the orthopaedic surgeon and staff from a mini C-arm fluoroscopy unit.  

PubMed

In this study, radiation exposure to the surgeon and supporting staff from a mini C-arm unit during fluoroscopically guided orthopaedic surgeries was studied. A Diadose dosemeter and Gamma-Scout meter were used for air-kerma measurements for primary and scattered radiations. The entrance dose of hands, eyes and thyroid of the surgeon was measured during direct observation. Scattered air-kerma rate was measured to quantify the received entrance dose of the supporting staff. During direct observation, the skin-entrance exposure rates of the surgeon's hand, eye and thyroid gland were 8036, 0.85 and 0.9 microGy min(-1), respectively. The scattered exposure rate was precipitously dropped beyond the path of the primary radiation beam, and reached 0.51 microGy min(-1) at a distance of 40 cm from the beam's central axis. This study showed that the surgeon's hand was the most dose-limiting organ for fluoroscopically guided orthopaedic surgery procedures when it was exposed to primary radiation. The exposure of supporting staff at a working distance of >20 cm from the beam was minimal during fluoroscopy by mini C-arm unit. PMID:18765404

Mesbahi, Asghar; Rouhani, Alireza

2008-01-01

185

Radiation exposure to nuclear medicine staff involved in PET/CT practice in Serbia.  

PubMed

The purpose of this work is to evaluate the radiation exposure to nuclear medicine (NM) staff in the two positron emission tomography-computed tomography centres in Serbia and to investigate the possibilities for dose reduction. Dose levels in terms of Hp(10) for whole body and Hp(0.07) for hands of NM staff were assessed using thermoluminescence and electronic personal dosemeters. The assessed doses per procedure in terms of Hp(10) were 4.2-7 and 5-6 ?Sv, in two centres, respectively, whereas the extremity doses in terms of Hp(0.07) in one of the centres was 34-126 ?Sv procedure(-1). The whole-body doses per unit activity were 17-19 and 21-26 ?Sv GBq(-1) in two centres, respectively, and the normalised finger dose in one centre was 170-680 ?Sv GBq(-1). The maximal estimated annual whole-body doses in two centres were 3.4 and 2.0 mSv, while the corresponding extremity dose in the later one was 45 mSv. Improvements as introduction of automatic dispensing system and injection and optimisation of working practice resulted in dose reduction ranging from 12 up to 67 %. PMID:24464817

Antic, V; Ciraj-Bjelac, O; Stankovic, J; Arandjic, D; Todorovic, N; Lucic, S

2014-12-01

186

Influence of lead apron shielding on absorbed doses from panoramic radiography  

PubMed Central

Objectives: This study investigated the absorbed doses in a full anthropomorphic body phantom from two different panoramic radiography devices, performing protocols with and without applying a lead apron. Methods: A RANDO® full body phantom (Alderson Research Laboratories Inc., Stamford, CT) was equipped with 110 thermoluminescent dosemeters at 55 different sites and set up in two different panoramic radiography devices [SCANORA® three-dimensional (3D) (SOREDEX, Tuusula, Finland) and ProMax® 3D (Planmeca, Helsinki, Finland)] and exposed. Two different protocols were performed in the two devices. The first protocol was performed without any lead shielding, whereas the phantom was equipped with a standard adult lead apron for the second protocol. Results: A two-tailed paired samples t-test for the SCANORA 3D revealed that there is no difference between the protocol using lead apron shielding (m?=?87.99, s?=?102.98) and the protocol without shielding (m?=?87.34, s?=?107.49), t(54)?=??0.313, p?>?0.05. The same test for the ProMax 3D showed that there is also no difference between the protocol using shielding (m?=?106.48, s?=?117.38) and the protocol without shielding (m?=?107.75, s?=?114,36), t(54)?=?0.938, p?>?0.05. Conclusions: In conclusion, the results of this study showed no statistically significant differences between a panoramic radiography with or without the use of lead apron shielding. PMID:24174012

Rottke, D; Grossekettler, L; Sawada, K; Poxleitner, P; Schulze, D

2013-01-01

187

PREPARATION AND CHARACTERISATION OF A SOL-GEL PROCESS ?-AL2O3 POLYCRYSTALLINE DETECTOR.  

PubMed

This article presents the dosimetric characteristics of ?-Al2O3 detectors prepared through the sol-gel process, disc pressing and sintering in a highly reducing atmosphere. Comparative tests between the sol-gel process ?-Al2O3 polycrystalline and anion-defective ?-Al2O3:C single-crystal detectors indicate that the ones prepared through this approach present good dosimetric characteristics similar to those found in single-crystal detectors, such as a simple glow curve with the main peak at ?198 °C (2 °C s(-1)), high sensitivity, a detection threshold of 1.7 µGy, linearity of response, low fading, relatively low photon energy dependence, reusability without annealing and good reproducibility. However, the undesirable feature of heating rate dependence of the thermoluminescence (TL) output in ?-Al2O3:C single crystal is practically non-existent in the sol-gel process ?-Al2O3 polycrystalline detector. This characteristic renders it useful for the routine processing of large numbers of personal and environmental dosemeters at higher heating rates and also when it comes to the proposal for new approaches to thermal quenching investigation. PMID:24795396

Ferreira, H R; Santos, A

2014-05-01

188

DOSIMETRIC FEATURE OF NATURAL BIOTITE MINERAL.  

PubMed

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

Kalita, J M; Wary, G

2014-09-16

189

Radiation Exposure to Patient and Staff in Hepatic Chemoembolization: Risk Estimation of Cancer and Deterministic Effects  

SciTech Connect

The purpose of the study was to determine the risks of radiation-induced cancer and deterministic effects for the patient and staff in transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC). Sixty-five patients with HCC underwent the first cycle of TACE. Thermoluminescence dosemeters and conversion factors were used to measure surface doses and to calculate organ doses and effective dose. For the patient, the risk of fatal cancer and severe genetic defect was in the magnitude of 10{sup -4} and 10{sup -5}, respectively. Five patients showed surface doses over the first lumbar vertebra exceeding 2000 mSv and 45 patients showed doses over the spine or the liver region above 500 mSv. The risk of fatal cancer and severe genetic defect for the radiologist and assistant was in the magnitude of 10{sup -7} to 10{sup -8}. They could exceed the threshold for lens opacity in the case of more than 490 and 1613 TACE yearly for a period of many years, respectively. Radiation dose could lead to local transient erythema and/or local depression of hematopoiesis in many patients after TACE. For the radiologist and assistant, risk of fatal cancer and genetic defect and lens opacity might arise when they perform interventions such as TACE intensively.

Hidajat, Nico, E-mail: nico.hidajat@gmx.de; Wust, Peter; Felix, Roland; Schroeder, Ralf Juergen [Charite Campus Virchow-Klinikum, Humboldt-University of Berlin, Department of Radiology (Germany)

2006-10-15

190

Determination of photon fluence spectra from the NPL Mobaltron Co-60 unit  

NASA Astrophysics Data System (ADS)

Absorbed dose to water calibrations of secondary standard hospital dosemeters are carried out in both x-radiation from 4 to 19 MV and in Co-60 gamma radiation. Measurements are performed using the primary standard graphite calorimeter and by inserting the secondary standard and working standard chambers at a reference depth in either a water or graphite phantom. Details of the dose distributions and the responses of these chambers in each phantom for the Co-60 radiation quality are, however, unknown. A knowledge of the photon fluence spectra produced by the Co-60 unit is therefore required to enable this analysis to be carried out. Work undertaken to determine the photon fluence spectra incident on the front face of the water and graphite phantoms under standard measurement conditions is described. The spectra were validated by comparing calculated tissue phantom ratios with recent experimental values. The calculated tissue phantom ratio (TPR) values were found to agree with measurements to within 1 to 2 sigma (total uncertainty), and also with independent estimates obtained using the program AVERMV. The observed discrepancies were primarily systematic in nature with the largest source of uncertainty being the change in beam quality, and hence chamber calibration factor, with depth in the phantom.

Shipley, D. R.; Duane, S.

1994-01-01

191

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

192

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

193

Personal radiation doses in PET/CT facility: measurements vs. calculations.  

PubMed

The estimation of shielding requirement of a new positron emission tomography (PET) facility is essential. Because of penetrating annihilation photons, not only radiation safety in the vicinity of patients should be considered, but also rooms adjacent to uptake and imaging rooms should be taken into account. Before installing a PET/CT camera to nuclear medicine facilities of Helsinki University Central Hospital (HUCH), a typical PET imaging day was simulated using phantoms. Phantoms were filled with 300 +/- 36 MBq of (18)F isotope and dose rates were measured at 12 central locations in the laboratory. In addition to measurements, dose rates were also calculated using guidelines of AAPM Task Group 108. The relationship between the measured and calculated dose rates was found to be good and statistically significant, using Pearson's correlation test. The evaluated monthly doses were compared with personal dosemeter readings. AAPM's report gives practical tools for evaluation of radiation shielding. Calculations can be carried out successfully for existing hospital complexes too. However, calculations should be carried out carefully, because especially doors, windows and partitions can easily cause underestimation of shielding requirements as shown in this work. PMID:18713782

Hippeläinen, E; Nikkinen, P; Ihalainen, T; Uusi-Simola, J; Savolainen, S

2008-01-01

194

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

PubMed

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. PMID:21464535

Struelens, Lara; Kauwenberghs, Kim; Vanhavere, Filip

2011-05-01

195

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

196

Small field of view cone beam CT temporomandibular joint imaging dosimetry  

PubMed Central

Objectives: Cone beam CT (CBCT) is generally accepted as the imaging modality of choice for visualisation of the osseous structures of the temporomandibular joint (TMJ). The purpose of this study was to compare the radiation dose of a protocol for CBCT TMJ imaging using a large field of view Hitachi CB MercuRay™ unit (Hitachi Medical Systems, Tokyo, Japan) with an alternative approach that utilizes two CBCT acquisitions of the right and left TMJs using the Kodak 9000® 3D system (Carestream, Rochester, NY). Methods: 25 optically stimulated luminescence dosemeters were placed in various locations of an anthropomorphic RANDO® Man phantom (Alderson Research Laboratories, Stanford, CT). Dosimetric measurements were performed for each technique, and effective doses were calculated using the 2007 International Commission on Radiological Protection tissue weighting factor recommendations for all protocols. Results: The radiation effective dose for the CB MercuRay technique was 223.6?±?1.1??Sv compared with 9.7?±?0.1??Sv (child), 13.5?±?0.9??Sv (adolescent/small adult) and 20.5?±?1.3??Sv (adult) for the bilateral Kodak acquisitions. Conclusions: Acquisitions of individual right and left TMJ volumes using the Kodak 9000 3D CBCT imaging system resulted in a more than ten-fold reduction in the effective dose compared with the larger single field acquisition with the Hitachi CB MercuRay. This decrease is made even more significant when lower tube potential and tube current settings are used. PMID:24048693

Lukat, T D; Wong, J C M; Lam, E W N

2013-01-01

197

Using GafChromic film to estimate the effective dose from dental cone beam CT and panoramic radiography  

PubMed Central

Objectives: To demonstrate the feasibility of GafChromic® XR-QA2 (ISP Corp., Wayne, NJ) as a dosemeter when performing measurements of the effective dose from three cone beam CT (CBCT) units and to compare the doses from examinations of three common dental clinical situations. A second aim was to compare the radiation doses for three digital panoramic units with the doses for the CBCT units. Methods: The CBCT units used were Veraviewepocs 3De® (J Morita MFG Corp., Kyoto, Japan), ProMax® 3D (Planmeca, Helsinki, Finland) and NewTom VGi® (Quantitative Radiology, Verona, Italy). GafChromic XR-QA2 films were placed between the selected layers of the head and neck of a tissue-equivalent human skull (RANDO® phantom; The Phantom Laboratory, Salem, NY). The exposure parameters were set using the automatic exposure control function of the units. Depending on the availability, medium and smaller field of view (FOV) scanning modes were used. The effective dose was estimated using the 2007 International Commission on Radiological Protection formalism. Results: The lowest effective dose of a CBCT unit was observed for ProMax 3D, FOV 4?×?5?cm (10??Sv), the highest for NewTom VGi, FOV 8?×?8?cm—high resolution (129??Sv). The range of effective doses for digital panoramic machines measured was 8–14??Sv. Conclusions: This study demonstrates the feasibility of using radiochromic films for dental CBCT and panoramic dosimetry. PMID:23610090

Al-Okshi, A; Nilsson, M; Petersson, A; Wiese, M; Lindh, C

2013-01-01

198

Assessment of the effective doses from two dental cone beam CT devices  

PubMed Central

Objectives: This study compares the effective dose for different fields of view (FOVs), resolutions and X-ray parameters from two cone beam CT units: the KaVo 3D (three-dimensional) eXam and the KaVo Pan eXam Plus 3D (KaVo Dental, Biberach, Germany). Methods: Measurements were made using thermoluminescent dosemeter chips in a radiation analog dosimetry head and neck phantom. The calculations of effective doses are based on the ICRP 60 and ICRP 103 recommendations of the International Commission on Radiological Protection. Results: Effective doses from the 3D eXam ranged between 32.8?µSv and 169.8?µSv, and for the Pan eXam Plus effective doses ranged between 40.2?µSv and 183.7?µSv; these were measured using ICRP 103 weighting factors in each case. The increase in effective dose between ICRP 60 and ICRP 103 recommendations averaged 157% for all measurements. Conclusions: Effective doses can be reduced significantly with the choice of lower resolutions and mAs settings as well as smaller FOVs to avoid tissues sensitive to radiation being inside the direct beam. Larger FOVs do not necessarily lead to higher effective doses. PMID:23420855

Schilling, R; Geibel, M-A

2013-01-01

199

Experimental simulation of personal dosimetry in production of medical radioisotopes by research reactor.  

PubMed

Due to their work conditions, research reactor personnel are exposed to ionising nuclear radiations. Because the absorbed dose values are different for different tissues due to variations in sensitivity, in this work personal dosimetry has been performed under normal working conditions at anatomical locations relevant to more sensitive tissues as well as for the whole body by employing a Rando phantom and thermoluminescent dosemeters (TLDs). Fifty-two TLDs-100H were positioned at high-risk organ locations such as the thyroid, eyes as well as the left breast, which was used to assess the whole-body dose in order to study the absorbed doses originating from selected locations in the vicinity of the reactor. The results have employed the tissue weighting factors based on International Commission on Radiological Protection ICRP 103 and ICRP 60 and the measured results were below the dose limits recommended by ICRP. The mean effective dose rates calculated from ICRP 103 were the following: whole body, 30.64-6.44 µSv h(-1); thyroid, 1.22-0.23 µSv h(-1); prostate, 0.085-0.045 µSv h(-1); gonads, 1.00-0.51 µSv h(-1); breast, 3.68-0.77 µSv h(-1); and eyes, 33.74-7.01 µSv h(-1). PMID:21862507

Mossadegh, N; Karimian, A; Shahhosseini, E; Mohammadzadeh, A; Sheibani, Sh

2011-09-01

200

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

PubMed Central

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

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

2012-01-01

201

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

202

The effect of 6 and 15 MV on intensity-modulated radiation therapy prostate cancer treatment: plan evaluation, tumour control probability and normal tissue complication probability analysis, and the theoretical risk of secondary induced malignancies  

PubMed Central

Objective The aim of this study was to investigate the effect of 6 and 15-MV photon energies on intensity-modulated radiation therapy (IMRT) prostate cancer treatment plan outcome and to compare the theoretical risks of secondary induced malignancies. Methods Separate prostate cancer IMRT plans were prepared for 6 and 15-MV beams. Organ-equivalent doses were obtained through thermoluminescent dosemeter measurements in an anthropomorphic Aldersen radiation therapy human phantom. The neutron dose contribution at 15 MV was measured using polyallyl-diglycol-carbonate neutron track etch detectors. Risk coefficients from the International Commission on Radiological Protection Report 103 were used to compare the risk of fatal secondary induced malignancies in out-of-field organs and tissues for 6 and 15 MV. For the bladder and the rectum, a comparative evaluation of the risk using three separate models was carried out. Dose–volume parameters for the rectum, bladder and prostate planning target volume were evaluated, as well as normal tissue complication probability (NTCP) and tumour control probability calculations. Results There is a small increased theoretical risk of developing a fatal cancer from 6 MV compared with 15 MV, taking into account all the organs. Dose–volume parameters for the rectum and bladder show that 15 MV results in better volume sparing in the regions below 70 Gy, but the volume exposed increases slightly beyond this in comparison with 6 MV, resulting in a higher NTCP for the rectum of 3.6% vs 3.0% (p=0.166). Conclusion The choice to treat using IMRT at 15 MV should not be excluded, but should be based on risk vs benefit while considering the age and life expectancy of the patient together with the relative risk of radiation-induced cancer and NTCPs. PMID:22010028

Hussein, M; Aldridge, S; Guerrero Urbano, T; Nisbet, A

2012-01-01

203

Monte Carlo design study for thick gas electron multiplier-based multi-element microdosimetric detector  

NASA Astrophysics Data System (ADS)

To accomplish enhanced neutron dose response with high detection efficiency, a set of multi-element microdosimetric detectors were designed using THick Gas Electron Multiplier (THGEM). THGEM generates a strong electric field within microholes of a sub-millimeter thick insulator, which makes electron multiplication possible without the traditional anode wire electrodes. Owing to the absence of wire electrodes, the newly designed neutron dosemeters offer flexible and convenient fabrication in contrast to the traditional multi-element tissue-equivalent proportional counters. In order to investigate the dependence of the neutron dosimetric response and detection efficiency on detector design, five designs with a different number of gas cavities and an identical outer diameter of 5 cm were created. For each design, a Monte Carlo simulation was developed using the Geant4 code to calculate the deposited energy spectrum in the gas cavities for mono-energetic neutron beams ranging from 10 keV to 2 MeV. From the simulation results, the microdosimetric and the absorbed dose responses of each multi-element design were consistent with the responses of the conventional single cavity detector. The quality factor and the dose equivalent responses were subsequently obtained and showed reasonable agreement with the ideal values for neutron energies above 300 keV while underestimating in the lower energy region. The neutron detection efficiency of each design was analyzed in terms of the neutron counts per incident fluence and the counts per dose equivalent. As the number of the multi-element cavities increased, both efficiencies increased greatly. The efficiency of the highest cavity density with 61×9 multi-elements was on average 5.6 times higher than that of the single cavity design. The 37×7 design could be chosen as a reasonable compromise between the two conflicting requirements, high efficiency and convenience in fabrication.

Anjomani, Z.; Hanu, A. R.; Prestwich, W. V.; Byun, S. H.

2014-09-01

204

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

205

Preliminary assessment of the dose to the interventional radiologist in fluoro-CT-guided procedures.  

PubMed

A preliminary assessment of the occupational dose to the intervention radiologist received in fluoroscopy computerised tomography (CT) used to guide the collection of lung and bone biopsies is presented. The main aim of this work was to evaluate the capability of the reading system as well as of the available whole-body (WB) and extremity dosemeters used in routine monthly monitoring periods to measure per procedure dose values. The intervention radiologist was allocated 10 WB detectors (LiF: Mg, Ti, TLD-100) placed at chest and abdomen levels above and below the lead apron, and at both right and left arms, knees and feet. A special glove was developed with casings for the insertion of 11 extremity detectors (LiF:Mg, Cu, P, TLD-100H) for the identification of the most highly exposed fingers. The H(p)(10) dose values received above the lead apron (ranged 0.20-0.02 mSv) depend mainly on the duration of the examination and on the placement of physician relative to the beam, while values below the apron are relatively low. The left arm seems to receive a higher dose value. H(p)(0.07) values to the hand (ranged 36.30-0.06 mSv) show that the index, middle and ring fingers are the most highly exposed. In this study, the wrist dose was negligible compared with the finger dose. These results are preliminary and further studies are needed to better characterise the dose assessment in CT fluoroscopy. PMID:21112883

Pereira, M F; Alves, J G; Sarmento, S; Santos, J A M; Sousa, M J; Gouvęa, M; Oliveira, A D; Cardoso, J V; Santos, L M

2011-03-01

206

AN ENGAGEMENT FACTOR FOR CAREGIVER RADIATION DOSE ASSESSMENT WITH RADIOIODINE TREATMENT.  

PubMed

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

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

2014-07-15

207

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

208

Shielding effect of thyroid collar for digital panoramic radiography  

PubMed Central

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

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

2013-01-01

209

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

PubMed

The health effects of cosmic radiation on astronauts need to be precisely quantified and controlled. This task is important not only in perspective of the increasing human presence at the International Space Station (ISS), but also for the preparation of safe human missions beyond low earth orbit. From a radiation protection point of view, the baseline quantity for radiation risk assessment in space is the effective dose equivalent. The present work reports the first successful attempt of the experimental determination of the effective dose equivalent in space, both for extra-vehicular activity (EVA) and intra-vehicular activity (IVA). This was achieved using the anthropomorphic torso phantom RANDO(®) equipped with more than 6,000 passive thermoluminescent detectors and plastic nuclear track detectors, which have been exposed to cosmic radiation inside the European Space Agency MATROSHKA facility both outside and inside the ISS. In order to calculate the effective dose equivalent, a numerical model of the RANDO(®) phantom, based on computer tomography scans of the actual phantom, was developed. It was found that the effective dose equivalent rate during an EVA approaches 700 ?Sv/d, while during an IVA about 20 % lower values were observed. It is shown that the individual dose based on a personal dosimeter reading for an astronaut during IVA results in an overestimate of the effective dose equivalent of about 15 %, whereas under an EVA conditions the overestimate is more than 200 %. A personal dosemeter can therefore deliver quite good exposure records during IVA, but may overestimate the effective dose equivalent received during an EVA considerably. PMID:25119442

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

2014-11-01

210

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

211

Skin dose measurements using radiochromic films, TLDS and ionisation chamber and comparison with Monte Carlo simulation.  

PubMed

Estimation of the surface dose is very important for patients undergoing radiation therapy. The purpose of this study is to investigate the dose at the surface of a water phantom at a depth of 0.007 cm as recommended by the International Commission on Radiological Protection and International Commission on Radiation Units and Measurement with radiochromic films (RFs), thermoluminescent dosemeters and an ionisation chamber in a 6-MV photon beam. The results were compared with the theoretical calculation using Monte Carlo (MC) simulation software (MCNP5, BEAMnrc and DOSXYZnrc). The RF was calibrated by placing the films at a depth of maximum dose (dmax) in a solid water phantom and exposing it to doses from 0 to 500 cGy. The films were scanned using a transmission high-resolution HP scanner. The optical density of the film was obtained from the red component of the RGB images using ImageJ software. The per cent surface dose (PSD) and percentage depth dose (PDD) curve were obtained by placing film pieces at the surface and at different depths in the solid water phantom. TLDs were placed at a depth of 10 cm in a solid water phantom for calibration. Then the TLDs were placed at different depths in the water phantom and were exposed to obtain the PDD. The obtained PSD and PDD values were compared with those obtained using a cylindrical ionisation chamber. The PSD was also determined using Monte Carlo simulation of a LINAC 6-MV photon beam. The extrapolation method was used to determine the PSD for all measurements. The PSD was 15.0±3.6 % for RF. The TLD measurement of the PSD was 16.0±5.0 %. The (0.6 cm(3)) cylindrical ionisation chamber measurement of the PSD was 50.0±3.0 %. The theoretical calculation using MCNP5 and DOSXYZnrc yielded a PSD of 15.0±2.0 % and 15.7±2.2 %. In this study, good agreement between PSD measurements was observed using RF and TLDs with the Monte Carlo calculation. However, the cylindrical chamber measurement yielded an overestimate of the PSD. This is probably due to the ionisation chamber calibration factor that is only valid in charged particle equilibrium condition, which is not achieved at the surface in the build-up region. PMID:24300340

Alashrah, Saleh; Kandaiya, Sivamany; Maalej, Nabil; El-Taher, A

2014-12-01