Calculation of gamma spectra in a plastic scintillator for energy calibrationand dose computation
In this study, the gamma spectra in a polystyrene scintillator were calculated for the energy calibration and dose computation. Based on the relationship between the energy resolution and estimated energy broadening effect in the calculated spectra, the gamma spectra were simply calculated without many iterations. The calculated spectra were in agreement with the calculation by an existing method and measurements. (Source: Radiation Protection Dosimetry)
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Kim, C., Yoo, H., Kim, Y., Moon, M., Kim, J. Y., Kang, D. U., Lee, D., Kim, M. S., Cho, M., Lee, E., Cho, G. Tags: Paper Source Type: research
Numerical simulation of direct measurement to determine thyroid 131i content of two tepco workers considering individual tissue thickness
In this study, the relationship between the count ratio (80.2/365 keV) and the thickness of soft tissue overlying the thyroid was investigated by means of numerical simulations performed using the Japanese Male (JM) phantom varying the thickness of the overlaying tissue. From the measured count ratios, it was possible to estimate that the overlaying tissue was thinner for Worker 1 (difference from the JM phantom: –0.34±1.29 cm) and thicker for Worker 2 (diff.: 2.5±1.2 cm). The thyroid 131I contents evaluated taking into account the individual thicknesses were 4.3 kBq for Worker 1 and 8.4 kBq for Worker ...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Tani, K., Kurihara, O., Kim, E., Sakai, K., Akashi, M. Tags: Paper Source Type: research
Creation of female computational phantoms for calibration of lung counters
Plutonium isotopes are of high concern because they lead to high doses. In case of contamination, the activity burden inside the lungs should be assessed accurately. Many studies showed that the presence of breasts has a substantial influence on lung counting efficiencies. Currently, the calibration of most lung counting systems is done by means of physical phantoms representing only male chests. A set of female computational phantoms has been developed in order to provide gender-specific efficiency calibrations for the 241Am gamma emission (59.54 keV). The phantoms were created starting from a library of female chest phan...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Lombardo, P. A., Lebacq, A. L., Vanhavere, F. Tags: Paper Source Type: research
Numerical assessment of 131i deposited in thyroid for non-standard situations
At the CIEMAT whole-body counter, a low-energy germanium detector is used for the in vivo assessment of 131I activity in thyroid, mainly for the individual monitoring programmes of workers. The detector is calibrated with a cylindrical neck phantom made of polymethyl methacrylate that mimics the neck of an adult, containing a vial with a radioactive solution. For an accurate activity assessment, it is necessary to perform the calibration of the detector with phantoms that closely reproduce the anatomy of a real person. Nevertheless, it is not affordable to count on a variety of physical phantoms covering the different anat...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Moraleda, M., Gomez-Ros, J. M. Tags: Paper Source Type: research
Crucial parameters for proper simulation of the detector used in in vivo measurements
Mathematical calibration is an increasingly popular technique among laboratories with a whole- or partial-body counters. A mathematical calibration employing a voxel phantom and Monte Carlo radiation transport code simulations has many benefits and can overcome many limitations of detector efficiency calibration using physical anthropomorphic phantoms. This publication tries to identify key factors for detector modelling. The influence of such parameters depends on energy and thus is studied in the gamma energy range of detectable radionuclides, i.e. from 15 keV to 1.5 MeV. (Source: Radiation Protection Dosimetry)
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Vrba, T. Tags: Paper Source Type: research
Monte carlo simulation of the bremsstrahlung radiation for the measurement of an internal contamination with pure-beta emitters in vivo
Rapid measurement techniques are required for a large-scale emergency monitoring of people. In vivo measurement of the bremsstrahlung radiation produced by incorporated pure-beta emitters can offer a rapid technique for the determination of such radionuclides in the human body. This work presents a method for the calibration of spectrometers, based on the use of UPh-02T (so-called IGOR) phantom and specific 90Sr/90Y sources, which can account for recent as well as previous contaminations. The process of the whole- and partial-body counter calibration in combination with application of a Monte Carlo code offers readily exte...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Fantinova, K., Fojtik, P., Malatova, I. Tags: Paper Source Type: research
MCNP SIMULATION OF THE HP(10) ENERGY RESPONSE OF A BRAZILIAN TLD ALBEDO NEUTRON INDIVIDUAL DOSEMETER, FROM THERMAL TO 20 MeV
The Brazilian Instituto de Radioprotecão e Dosimetria (IRD) runs a neutron individual monitoring system with a home-made TLD albedo dosemeter. It has already been characterised and calibrated in some reference fields. However, the complete energy response of this dosemeter is not known, and the calibration factors for all monitored workplace neutron fields are difficult to be obtained experimentally. Therefore, to overcome such difficulties, Monte Carlo simulations have been used. This paper describes the simulation of the HP(10) neutron response of the IRD TLD albedo dosemeter using the MCNPX transport code, for en...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Freitas, B. M., Martins, M. M., Pereira, W. W., da Silva, A. X., Mauricio, C. L. P. Tags: Paper Source Type: research
ENVIRONMENTAL DOSIMETRY WITH THE BeOSL PERSONAL DOSEMETER
In the course of this work, a dosemeter for measurement of ambient dose equivalent H*(10) based on the BeOSL dosimetry system was designed. Calculations of the energy response of the two-element BeOSL personal dosemeter in terms of H*(10) showed that the response does not fulfil the requirements of IEC 62387. Especially, the response for photon energies of 60–100 keV is too low. It is possible to correct this under-response using a BeOSL two-element dosemeter, a linear algorithm and an additional cover for the dosemeter. The Hp(0.07) element is shielded with lead, and with the help of a linear algorithm, corrections ...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Jahn, A., Sommer, M., Henniger, J. Tags: Paper Source Type: research
Environmental monitoring with passive detectors at ctn in portugal
The aim of this work is to present the methods in use for environmental dose assessment with passive detectors at Campus Tecnológico e Nuclear (CTN) of Instituto Superior Técnico, in Portugal. The methods are based on LiF:Mg,Ti (TLD-100) detectors inserted in Harshaw holders placed at four locations and exchanged on a quarterly basis. An initial group of measurements allowed the estimation of the time interval necessary to attain a stable value, the determination of a fading factor, as well as the calculation method for the assessment of the ambient dose equivalent rate. (Source: Radiation Protection Dosimetry)
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Pereira, M. F., Pereira, J., Rangel, S., Saraiva, M., Santos, L. M., Cardoso, J. V., Alves, J. G. Tags: Paper Source Type: research
Secondary neutron doses in a proton therapy centre
The formation of secondary high-energy neutrons in proton therapy can be a concern for radiation protection of staff. In this joint intercomparative study (CERN, SCK•CEN and IBA/IRISIB/ULB), secondary neutron doses were assessed with different detectors in several positions in the Proton Therapy Centre, Essen (Germany). The ambient dose equivalent H*(10) was assessed with Berthold LB 6411, WENDI-2, tissue-equivalent proportional counter (TEPC) and Bonner spheres (BS). The personal dose equivalent Hp(10) was measured with two types of active detectors and with bubble detectors. Using spectral and basic angular informat...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: De Saint-Hubert, M., Saldarriaga Vargas, C., Van Hoey, O., Schoonjans, W., De Smet, V., Mathot, G., Stichelbaut, F., Manessi, G., Dinar, N., Aza, E., Cassell, C., Silari, M., Vanhavere, F. Tags: Paper Source Type: research
Radon and progeny sourced dose assessment of spa employees in balneological sites
This study was conducted in the scope of IAEA project with the name ‘Establishing a Systematic Radioactivity Survey and Total Effective Dose Assessment in Natural Balneological Sites’ (TUR/9/018), at the Health Physics department of Sarayköy Nuclear Research and Training Center (SANAEM). The aim of this study is estimation of radon and progeny sourced effective dose for the people who are working at the spa facilities by measuring radon activity concentration (RAC) at the ambient air of indoor spa pools and dressing rooms. As it is known, the source of the radon gas is the radium content of the earth cr...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Uzun, S. K., Demiröz, I. Tags: Paper Source Type: research
A single-exposure, multidetector neutron spectrometer for workplace monitoring
This communication describes a recently developed single-exposure neutron spectrometer, based on multiple active thermal neutron detectors located within a moderating sphere, which have been developed jointly by CIEMAT (Spain), INFN (Italy) and Politecnico di Milano (Italy) in the framework of Italian and Spanish collaboration projects. The fabricated prototypes permit to achieve spectrometric resolution with nearly isotropic response for neutron with energies from thermal to 100–200 MeV, thus being able to characterise the complete neutron spectrum in only one exposure by unfolding the measured responses of the dete...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Bedogni, R., Bortot, D., Buonomo, B., Esposito, A., Gomez-Ros, J. M., Introini, M. V., Mazzitelli, G., Moraleda, M., Pola, A., Romero, A. M. Tags: Paper Source Type: research
Dose to radiological technologists from induced radionuclides in carbon ion radiotherapy
In this study, annual doses to RTs working in a carbon ion radiotherapy facility were estimated based on measurements with the Si-semiconductor personal dosemeter. In addition, the time decay of dose around a patient couch after irradiation was obtained by phantom experiments. The annual Hp(10) values for passive and scanned beams were estimated to be 61 and 2 μSv, respectively, when assuming the number of treatments in 2013. These are much lower than the ICRP recommended dose limit for radiation workers. The time-series data of dose to RTs during their work and the time decay of the dose should be helpful for reducing ...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Yonai, S., Spano, V. Tags: Paper Source Type: research
Response of dosemeters in fields generated by laser-accelerated protons
In laser-driven acceleration, ultra-short and intense laser pulses are focussed on targets to generate beams of ionising radiation. One of the most important issues to be addressed is personal monitoring. While traditional dosemeters were designed primarily for measurements in continuous fields, dosemeters for laser laboratories must be capable of working in pulsed fields of pulse length below 1 ps, in a single-shot regime up to the repetition rate of 1 kHz. Responses of conventional dosemeters (films, polyallyldiglycol carbonate, electronic personal dosemeter) to proton bunches of up to 30 MeV energy produced by South Kor...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Olsovcova, V., Versaci, R., Ambrozova, I., Zelenka, Z., Kaufman, J., Margarone, D., Kim, I. J., Jeong, T. M. Tags: Paper Source Type: research
Three-year retention of radioactive caesium in the body of tepco workers involved in the fukushima daiichi nuclear power station accident
Direct measurements of seven highly exposed workers at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station accident have been performed continuously since June 2011. Caesium clearance in the monitored workers is in agreement with the biokinetic models proposed by the International Commission on Radiological Protection. After 500 d from the initial measurement, however, the caesium clearance slowed. It was thought to be unlikely that additional Cs intake had occurred after the initial intake, as activity in foods was kept low. And, the contribution from the detector over the chest was enhanced with time...
Source: Radiation Protection Dosimetry - September 7, 2016 Category: Radiology Authors: Nakano, T., Tani, K., Kim, E., Kurihara, O., Sakai, K., Akashi, M. Tags: Paper Source Type: research
