Radiation Protection Dosimetry - recent issues

Patient dose studies: what should be reported?

Martin, C. J. — 2008-06-04

Radiation dosimetry for diagnostic medical exposures

Martin, C. J. — 2008-06-04

The number and complexity of medical procedures using X rays or radioactive materials are both steadily increasing. As a result, the dose from medical exposures now makes up the largest component of the radiation dose to the population in some developed countries. Key developments include the change from film to digital radiography, the increasing sophistication of interventional radiology allowing more complex procedures and the speed and facilities available with multi-slice computed tomography scanners that have extended the range of applications. It is crucial to have accurate dosimetry to monitor the impact of these developments, to ensure that techniques are optimised, and to provide information on health risk that clinicians can consider when justifying exposures. There are two aspects to dosimetry in radiology, assessment of doses to patients and measurement of equipment performance. The techniques that are used will be described, factors that influence doses and that must be considered when making measurements will be discussed, and future developments will be considered.

Neutron microdosimetric response of a gas electron multiplier

Dubeau, J., Waker, A. J. — 2008-06-04

A new high-sensitivity tissue equivalent proportional counter (TEPC) on the basis of the gas electron multiplier (GEM) detector used in high-energy physics experiments has been designed, constructed and tested in a variety of neutron fields. The GEM–TEPC makes use of a lithographically produced strip readout system to achieve the equivalent of a large number of miniature TEPC detector elements. This new device could be used as the basis of an electronic personal dosemeter for gamma and neutron mixed radiation fields.

Automated detection of irradiated food with the comet assay

Verbeek, F., Koppen, G., Schaeken, B., Verschaeve, L. — 2008-06-04

Food irradiation is the process of exposing food to ionising radiation in order to disinfect, sanitise, sterilise and preserve food or to provide insect disinfestation. Irradiated food should be adequately labelled according to international and national guidelines. In many countries, there are furthermore restrictions to the product-specific maximal dose that can be administered. Therefore, there is a need for methods that allow detection of irradiated food, as well as for methods that provide a reliable dose estimate. In recent years, the comet assay was proposed as a simple, rapid and inexpensive method to fulfil these goals, but further research is required to explore the full potential of this method. In this paper we describe the use of an automated image analysing system to measure DNA comets which allow the discrimination between irradiated and non-irradiated food as well as the set-up of standard dose–response curves, and hence a sufficiently accurate dose estimation.

Evaluation of specific absorbed fractions from internal photon sources in ORNL analytical adult phantom

Hakimabad, H. M., Motavalli, L. R. — 2008-06-04

To design a diagnostic or therapeutic irradiation programme, there is a need to estimate the absorbed dose. In this investigation, specific absorbed fractions (SAFs) were calculated based on Cristy and Eckerman's analytical adult phantom, by MCNP4C Monte Carlo code. SAFs were estimated with uncertainty <3%, for about 600 source organ–target organ pairs at 12 photon energies (these data are available at http://www.um.ac.ir/~mirihakim). Then these results were compared with Cristy and Eckerman's, which were based on direct Monte Carlo, reciprocity principle and point source kernel methods. Also, agreements and disagreements between them for different states were discussed.

Indoor radon survey in dwellings of the Kars province, Turkey

Celik, N., Poffijn, A., Cevik, U., Schepens, L. — 2008-06-04

Makrofol Solid State Nuclear Track Detectors were used to study the ²²²Radon concentration in dwellings of the Kars province in Turkey. Radon measurements were done for 3 months in 87 houses, selected as uniformly distributed in the area as possible. All values were seasonally corrected. In order to define the seasonal correction factors, the readings were taken in 12 homes for a 12-month period. A 1:100.000 scale geologic map of the region, prepared and published by the Institute of Mineral Research and Exploration (Ankara, Turkey), was used to present the radon results. Digitising, processing and integrating of the data were performed by using ArcView GIS. The results of the radon measurements in the study area range from 20 to 600 Bq/m³, with 114 Bq/m³ as average value. The results showed that the number of lung cancer deaths attributable to indoor radon exposure was estimated to be ~5.

Confidence limits for Neyman type A-distributed events

2008-06-04

The Neyman type A distribution, a generalised, ‘contagious’ Poisson distribution, finds application in a number of disciplines such as biology, physics and economy. In radiation biology, it best describes the distribution of chromosomal aberrations in cells that were exposed to neutrons, alpha radiations or heavy ions. Intriguingly, no method has been developed for the calculation of confidence limits (CLs) of Neyman type A-distributed events. Here, an algorithm to calculate the 95% CL of Neyman type A-distributed events is presented. Although it has been developed in response to the requirements of radiation biology, it can find application in other fields of research. The algorithm has been implemented in a PC-based computer program that can be downloaded, free of charge, from www.pu.kielce.pl/ibiol/neta.

Variations in occupational exposure to magnetic fields among welders in Malaysia

Man, A.-K., Shahidan, R. — 2008-06-04

This study attempted to estimate the lifelong magnetic field (MF) exposures of a particular group of welders. Exposure was quantified via measurements, observations and interviews. It was found that these welders face a vast range of lifelong MF exposures depending on the welding processes and duration of the welding tasks performed. This may explain the inconsistency in the results of studies of MF exposures on human health. The mere assessing of the MF exposure levels through spot measurements does not give an overall picture of the total amount of exposure received by the welders as some of these workers performed the welding task throughout the day, whereas others performed this as a part of their job. The exposure to various chemicals in the fume may complicate the interpretation of the elevated health risk among the welders.

Effect of an aerosol deposition pattern in the lung on the counting efficiency of a large area germanium detector array

Kramer, G. H., Hauck, B. M. — 2008-06-04

The Human Monitoring Laboratory has extended the use of sliced lungs containing planar sources to simulate heterogeneous radionuclide deposition patterns. This work examined two deposition patterns and their effect on the counting efficiency of low-energy photons. The results have shown that heterogenous distributions can be difficult to detect in some cases and can still lead to large uncertainties (up to a factor of 2.5) in the activity estimate, especially at low photon energies. At higher energies (~60 keV), the effect of the heterogeneous distribution is greatly reduced and errors in the activity estimate reduced to ~25%. The presence of a heterogenous distribution can be detected by comparing the ratio of the individual detector counts with the expected values obtained from measuring multiple lungs sets that contained a homogeneous distribution. The distributions tested in this paper were detectable (at 2) as heterogeneous by two of the four detectors in the counting array.

Direct high-resolution alpha spectrometry from nuclear fuel particles in an outdoor air sample

Pollanen, R., Siiskonen, T. — 2008-06-04

The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are ²⁴²Cm, ²³⁹Pu and ²⁴⁰Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra.

Assessment of occupational exposure to magnetic fields in high-voltage substations (154/34.5 kV)

Helhel, S., Ozen, S. — 2008-06-04

This work proposes the survey of magnetic field measurements taken in 154/31.5 kV substations in the city of Antalya for occupational exposure assessment. For measurements, three substations have been taken into account, where four occupants are present for each 8 h of shift, which means 12 occupants are present during the day. Operator desks at three different substations read a lowest magnetic field of 0.3 µT at minimum loaded season and reached up to 1 µT at maximum loaded season, which means operators exposed to a magnetic field of ≥ 0.3 µT 8 h d^–1. In switch gear regions, maximum magnetic field reading is 23 µT at minimum loaded season and reached up to 70 µT. Outdoor magnetic field measurement at circuit breaker region goes up to 62 µT with respect to operator heights.

Radionuclide content and associated radiation hazards of building materials and by-products in Baoji, West China

Lu, X., Zhang, X. — 2008-06-04

Seven types of common building materials and by-products of coal-fired power plants collected from Baoji, West China, were analysed for the natural radioactivity of ²²⁶Ra, ²³²Th and ⁴⁰K using gamma ray spectrometry with an NaI(Tl) detector. The average activity concentrations vary from 23.0 to 112.2, 20.2 to 147.5 and 113.2 to 890.8 Bq kg^–1 for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The measured activity concentrations for these radionuclides were compared with the data reported from other countries and with the worldwide average activity of soil. As a measure of radiation hazard to the people, the radium equivalent activities, total annual effective dose and activity concentration index were estimated. The radium equivalent activities of the studied samples are below the internationally accepted values. The calculated total annual effective dose and the activity concentration index of seven types of common building materials are <1 mSv y^–1 and 1, respectively. But fly ash and bottom ash exhibit the higher values that exceed and be close to the acceptable values, respectively. This study shows that the measured building materials do not pose any significant source of radiation hazard and are safe for use in the construction of dwellings. Nevertheless, when fly ash and bottom ash are used in dwelling construction, it is important to assess their radiation potential.

Determination of natural radioactivity in drinking water in private dug wells in Akure, Southwestern Nigeria

Ajayi, O. S., Owolabi, T. P. — 2008-06-04

Gamma spectrometry of well water was done to measure the activity concentrations of gamma-emitters ²²⁶Ra and ²²⁸Ra from ²³⁸U and ²³²Th series, respectively, and ⁴⁰K in their waters. Measurements were done using high-purity (HPGe) co-axial detectors (Canberra, GC 2018-7500 ) coupled to Canberra Multichannel Analyser system. Activity concentrations ranged from 0.57 to 26.86, 0.20 to 60.06 and 0.35 to 29.01 Bq l^–1 for ²²⁶Ra, ²²⁸Ra and ⁴⁰K, respectively. Activity concentrations were compared with data from other parts of the world and used to estimate annual effective dose for three age groups. Total annual effective doses from the intake of these radionuclides in the waters ranged from 0.02 to 76.84, 0.02 to 38.80 and 0.05 to 481.60 mSv y^–1 for age group <1, 2–7 and ≥17 y, respectively. These values are considerably higher than both the World Health Organisation and the International Commission on Radiological Protection limits.

Patient dosimetry in interventional cardiology at the University Hospital of Osijek

2008-06-04

The interventional cardiology was recently implemented at the University Hospital of Osijek. Patients' absorbed doses during coronary angiography (CA) and the percutaneous transluminal coronary angioplasty (PTCA) procedures were measured and compared with published data and international standards. All patients undergoing CA or PTCA procedures during a 1-month period were included in the study. Patients' doses are expressed in terms of dose area product (DAP) per procedure. The patients' DAPs ranged from 2.6 to 210 Gy cm² (average of 59 Gy cm²) during CAs, and from 61 to 220 Gy cm² (average of 120 Gy cm²) during PTCAs. Patients' doses during CAs and PTCAs at the University Hospital of Osijek are in good agreement with the published ones. In complex cases, the radiochromic dosimetry films were used to show possible dose distributions across patient's skin. The film dosimetry showed a limitation of using only DAP values for the estimation of skin injuries risk.

Dose level of occupational exposure in China

Tian, Y., Zhang, L., Ju, Y. — 2008-06-04

This paper discusses the dose level of Chinese occupational exposures during 1986–2000. Data on occupational exposures from the main categories in nuclear fuel cycle (uranium enrichment and conversion, fuel fabrication, reactor operation, waste management and research activity, except for uranium mining and milling because of the lack of data), medical uses of radiation (diagnostic radiation, nuclear medicine and radiotherapy) and industrial uses of radiation (industrial radiography and radioisotope production) are presented and summarised in detail. These are the main components of occupational exposures in China. In general, the average annual effective doses show a steady decreasing trend over periods: from 2.16 to 1.16 mSv in medical uses of radiation during 1990–2000; from 1.92 to 1.18 mSv in industrial radiography during 1990–2000; from 8.79 to 2.05 mSv in radioisotope production during the period 1980–2000. Almost all the average annual effective doses in discussed occupations were lower than 5 mSv in recent years (except for well-logging: 6.86 mSv in 1999) and no monitored workers were found to have received the occupational exposure exceeding 50 mSv in a single year or 100 mSv in a five-year period. So the Chinese protection status of occupation exposure has been improved in recent years. However, the average annual effective doses in some occupations, such as diagnostic radiology and coal mining, were still much higher than that of the whole world. There are still needs for further improvement and careful monitoring of occupational exposure to protect every worker from excessive occupational exposure, especially for the workers who were neglected before.

A method for calculation of radiation quantities at all points in gamma radiation calibration fields

2008-06-04

Radiation quantity values at all points of a known distance range of gamma radiation calibration fields were calculated using a mathematical method. The method is based on interpolation using Chi-square test on a set of experimental data at optional points of both collimated and un-collimated calibration set-ups by means of a reference instrument. In comparison with Monte Carlo calculations, the values that were calculated by this method differ by <1% for collimated and 2% for un-collimated calibration set-ups. Consequently, the radiation quantities at all points of gamma radiation calibration field set-ups can accurately be formulated and determined by this method. In addition, all points in the radiation fields can be regarded as test points.

One cubic metre NIST traceable radon test chamber

Kotrappa, P., Stieff, F. — 2008-06-04

With the availability of the National Institute of Standards and Technology (NIST) Radon Emanation Standard with a content of ~5000 Bq of ²²⁶Ra, it is possible to build a flow through a practical radon test chamber. A standard glove box with four gloves and a transfer port is used. Air is pumped through a flow integrator, water jar for humidification and NIST source holder, and into the glove box through a manifold. A derived theoretical expression provides the calculated radon concentration inside the chamber. The calculation includes a derived decay correction due to the large volume and low flow rate of the system. Several calibrated continuous radon monitors and passive integrating electret ion chambers tested in the chamber agreed fairly well with the calculated radon concentrations. The chamber is suitable for handling the calibration of several detectors at the same time.

Effective dose: a useful concept in diagnostic radiology?

Brenner, D., Huda, W. — 2008-06-04

Letters to the Editor

German, U., Weinstein, M., Abraham, A., Alfassi, Z. B. — 2008-06-04

Letters to the Editor

Horowitz, Y. S. — 2008-06-04

Radon transport through concrete and determination of its diffusion coefficient

Nikezic, D., Urosevic, V. — 2008-06-04

Limitations of the Use of the Vertical Cut-off to Calculate Cosmic-ray Propagation in the Earth's Atmosphere

O'Brien, K. — 2008-06-04

OSL and TL in LiF:Mg,Ti following alpha particle and beta ray irradiation: application to mixed-field radiation dosimetry

Oster, L., Horowitz, Y. S., Podpalov, L. — 2008-06-04

The optically stimulated luminescence (OSL) of LiF:Mg,Ti (TLD-100) following irradiation by beta and alpha particles was investigated by the measurement of the excitation and emission spectra of OSL and comparison with thermoluminescence (TL) characteristics. Measurements were also carried out on nominally pure LiF monocrystals. The preferential excitation of OSL compared to TL following high-ionisation density (HID) alpha irradiation is naturally explained via the identification of OSL with the ‘two-hit’ F₂ or F₃⁺ centre, whereas the major component of composite TL glow peak 5 is believed to arise from a ‘one-hit’ complex defect. This discovery allows near-total discrimination between HID radiation and low-ionisation density radiation and may have significant potential in mixed-field radiation dosimetry.

Studies on the response of the TLD badge for high-energy photons

Kumar, M., Kher, R. K., Sahni, G., Chhokra, K. — 2008-06-04

Absorbed tissue dose measurements are carried out for high-energy photon beams using CaSO₄:Dy thermo-luminescence dosemeter (TLD) badge and the results are also verified using ionisation chamber used in radiation therapy. The photon beams generated using linear accelerator at 6 and 18 MV photon beam energies have been used and the absorbed doses are measured at the surface as well as at various depths. It has been found that the depth at which maximum dose is delivered increases with the increase in photon energy and the depth of maximum absorbed dose in tissue occurs beyond 10 mm. It has also been found that the evaluation of the absorbed dose (or Hp(10) as well) using thermoluminescence readout of disc D1 clearly shows that the current TLD badge provides a reasonable estimate of the effective dose for photon fields from 6 to 18 MV linacs for anterior–posterior incidence. The paper also provides information regarding the misinterpretation of radiation pattern in multi-element/filter TLD badge.

Dose to persons assisting voluntarily during X-ray examinations of large animals

Hupe, O., Ankerhold, U. — 2008-06-04

Pet owners often assist voluntarily while their pets are being X-rayed during a medical examination. Medical staff members occupationally exposed to radiation are monitored regularly, as they wear personal dosemeters, whereas no dose measurements are carried out on voluntarily assisting persons, as measurements are both cost- and time-intensive. However, the dose limits prescribed in the German radiation protection regulations have to be observed for these volunteers as well. To assist the legislator in deciding whether the German regulation should be changed so that in future the dose of voluntarily assisting persons should also be determined—either by wearing a dosemeter or in another way—investigations with regard to the radiation dose exposure suffered by volunteers were performed within the scope of a research project. The personal dose equivalent H_p(10) for persons assisting knowingly and willingly in X-ray examinations in veterinary medicine was measured for different examination scenarios. Typical exposure situations have been identified and measurements performed in the field of scattered X-rays. The measurements were carried out on animals in veterinary practices and, to verify these measurements, also under laboratory conditions. This paper deals with X-ray examinations of large animals, with the focus especially on horses. The measured personal dose equivalent values of voluntary helpers in equine radiology are in the order of a few microsieverts.

Optimised geometry to calculate dose rate conversion coefficient for external exposure to photons

Askri, B., Manai, K., Trabelsi, A., Baccari, B. — 2008-06-04

A single-parameter geometry to describe soil is achieved for Monte Carlo calculation of absorbed dose rate in air for photon emitters from natural radionuclides. This optimised geometry based on physical assumptions consists of the soil part whose emitted radiation has a given minimum probability to reach the detector. This geometry was implemented in Geant4 toolkit and a significant reduction in computation time was achieved. Simulation tests have shown that for soil represented by a cylinder of 40 m radius and 1 m deep, >98% of the calculated dose rate conversion coefficients in air at 1 m above the ground is generated by only 6% of the soil volume in the case of uniform distribution of radioactivity, and >99.2% of the calculated dose rate for an exponential distribution. When the soil is represented by the entire optimised geometry, 99% of the conversion coefficients values are reached for a soil depth of 1 m and 100% for that of ~2 m.

Study of a gold-foil-based multisphere neutron spectrometer

Wang, Z., Hutchinson, J. D., Hertel, N. E., Burgett, E., Howell, R. M. — 2008-06-04

Multisphere neutron spectrometers with active thermal neutron detectors cannot be used in high-intensity radiation fields due to pulse pile-up and dead-time effects. Thus, a multisphere spectrometer using a passive detection system, specifically gold foils, has been investigated in this work. The responses of a gold-foil-based Bonner sphere neutron spectrometer were studied for two different gold-foil holder designs; an aluminium-polyethylene holder and a polyethylene holder. The responses of the two designs were calculated for four incident neutron beam directions, namely, parallel, perpendicular and at ± 45° relative to the flat surface of the foil. It was found that the use of polyethylene holder resulted in a more isotropic response to neutrons for the four incident directions considered. The computed responses were verified by measuring the neutron spectrum of a ²⁵²Cf source with known strength.

Study of Zeff for DNA, RNA and retina by numerical methods

Suresh, K. C., Manjunatha, H. C., Rudraswamy, B. — 2008-06-04

The effective atomic number of a biomolecule for photon interaction present in DNA, RNA and retina has been estimated in the energy range 0.001–20 MeV using two different numerical methods. The significant variation of Z_eff with photon energy is reported. This shows that Z_eff is not constant with energy for photon interaction in DNA, RNA and retinal.

Radiation doses from some [3H]-labelled organic compounds following ingestion

Taylor, D. M. — 2008-06-04

Published information, especially human data, on the biokinetics of 11 compounds labelled with ³H was used to develop simple, cautious compound-specific models and to calculate both tissue absorbed doses and effective doses using the OLINDA computer code. The compounds were [³H]-cortisol, 3-Hydroxy-5β-pregnane-11, 20-dione-7-[³H], cyclic 20 trimethylene acetal, [³H]-ifetroban, [³H]-digoxin, 7-[2'--methylphenylethylamino[³H]]theophylline, 7-[2'--methylphenylethylamino]theophylline-[³H], [³H]-amphetamine, [17³H]-nicergoline, [³H]-colestipol, [³H]-5(S)-benzamido-4-oxo-6-phenylhexanoyl-l-proline and [6-³H]-thymidine. The calculated effective doses ranged from 6 to 87% of that predicted by the ICRP default model for uncharacterised organic compounds of tritium (OBTM). For all the compounds studied, the retention of ³H in the body was less than that predicted by the OBTM and the route of excretion was found to influence both tissue and effective doses. It is concluded that although the ICRP OBT model may underestimate doses for specific compounds by up to an order of magnitude, it can still be applied with caution for prospective radiological protection purposes, but it should not be applied for the interpretation of bioassay data.

Use of the mini C-arm for wrist fractures--establishing a diagnostic reference level

Love, G. J., Pillai, A., Gibson, S. — 2008-06-04

The establishment of diagnostic reference levels (DRLs) for all typical radiological examinations became mandatory following the implementation of the Ionising Radiations (Medical Exposure) Regulations Act 2000. At present, there are no national dosage guidelines in the UK regarding use of fluoroscopy in orthopaedic trauma. The increasing popularity of the mini C-arm image intensifier amongst surgeons has led to concerns regarding use of ionizing radiation by personnel who have not been trained in radiation protection. It is therefore essential to have formal protocols for use of the mini C-arm to comply with the law and to maintain safe clinical practice. It is attempted to provide dose data for wrist fracture manipulations that may be used as a basis for setting a DRL for this procedure. Screening times were recorded for 80 wrist manipulations in a fracture clinic setting using a mini C-arm image intensifier. A DRL was set using the third quartile value for screening time. The median screening time for wrist fractures was 20 s with a range from 1 to 177 s. The third quartile value for screening time was 34 s. This value can be used as a provisional DRL for wrist fracture manipulations. The DRL is a quantitative guide for the optimisation of radiological protection. IR(ME)R 2000 states that if it is consistently exceeded by an individual operator or a piece of equipment, investigation and remedial action must be taken. We recommend that trauma units establish their own local DRLs for common procedures as made mandatory by legislation.

A large-scale multicentre study in Belgium of dose area product values and effective doses in interventional cardiology using contemporary X-ray equipment

Bogaert, E., Bacher, K., Thierens, H. — 2008-06-04

In this paper, a large-scale multicentre patient dose study performed in eight Belgian interventional cardiology departments is presented. Effective dose (E) was calculated based on a detailed dose–area product (DAP)-registration during each procedure and by using conversion coefficients generated by the Monte Carlo-based computer program PCXMC. Conversion coefficients were found to be 0.177 mSv Gycm^–2 for systems that do not use any additional copper filtration in cineradiography and 0.207 mSv Gycm^–2 for systems that use additional copper filtration in cineradiography. Mean E values of 9.6 and 15.3 mSv for diagnostic and therapeutic procedures, respectively, were obtained. DAP distributions were investigated in order to derive dose reference levels: 71 and 106 Gycm² for diagnostic and therapeutic procedures, respectively, are proposed. Significant differences were observed in DAP distributions taking into account whether additional copper filtration was used in the cineradiography mode. Apart from the skin, the organs most at risk are lungs and heart. The probability of fatal cancer for the studied population amounted to 1.1 x 10^–4 and 2.1 x 10^–4 for diagnostic and therapeutic procedures, respectively, for the age distribution of the patients considered in this multicentre study.

Radioactivity concentrations and dose assessment in surface soil samples from east and south of Marmara region, Turkey

2008-06-04

The activity concentrations of ¹³⁷Cs, ⁴⁰K, ²³²Th, ²³⁸U and ²²⁶Ra were measured in surface soil samples from East and South of Marmara region, Turkey. The physico-chemical parameters (organic matter, CaCO₃ contents and pH-value) of the soil samples were determined in the samples collected from 100 sampling stations. The average activity concentrations of ¹³⁷Cs, ⁴⁰K, ²³²Th, ²³⁸U and ²²⁶Ra were found to be 27.46 ± 21.84, 442.51 ± 189.85, 26.63 ± 15.90, 21.77 ± 12.08 and 22.45 ± 13.31 Bq kg^–1, respectively. The mean value of total annual external gamma radiation dose equivalent for the natural radionuclides was calculated to be 54.86 µSv. The current data were compared with those found in the other locations of Turkey and different countries.

Natural radioactivity and dose estimation in underground water from the Sudety Mountains in Poland

Kozlowska, B., Walencik, A., Dorda, J. — 2008-06-04

Studies of natural radioactivity in spring water in Swieradów – Czerniawa Health Resort were performed with the use of nuclear and mass spectrometry techniques. The investigated region is situated in the Sudety Mountains, where uranium exploration was conducted in the early 1950s of the last century. Annual effective doses due to radionuclide intake were calculated for 4 out of 20 spring waters used for consumption by spa patients and inhabitants. The summed effective doses without ²²²Rn were of the range 0.4 µSv to 9.2 µSv, for patient for of a 20-day duration stay and from 1.3 µSv y^–1 to 26.7 µSv y^–1 for an inhabitant. The contribution of radon consumed with water raises these values to 209.4 µSv per 20 days and 608.3 µSv y^–1 for a patient and inhabitant, respectively.

Measurements of non-target organ doses using MOSFET dosemeters for selected IMRT and 3D CRT radiation treatment procedures

Wang, B., Xu, X. G. — 2008-06-04

Many expressed concerns about the potential increase in second cancer risk from the widespread shift to intensity-modulated radiation therapy (IMRT) techniques from traditional 3-D conformal radiation treatment (3D CRT). This paper describes the study on in-phantom measurements of radiation doses in organ sites away from the primary tumour target. The measurements involved a RANDO^® phantom and Metal Oxide Semiconductor Field Effect Transistor dosemeters for selected 3D CRT and IMRT treatment plans. Three different treatment plans, 4-field 3D CRT, 6-field 3D CRT and 7-field IMRT for the prostate, were considered in this study. Steps to reconstruct organ doses from directly measured data were also presented. The dosemeter readings showed that the doses decrease as the distances increase for all treatment plans. At 40 cm from the prostate target, doses were <1% of the therapeutic dose. At this location, however, the IMRT plan resulted in an absorbed dose from photons, that is a factor of 3–5 higher than the 3D CRT treatment plans. This increase on absorbed dose is due to the increased exposure time for delivering the IMRT plan. The total monitor unit (MU) was 2850 for the IMRT case, while the MU was 1308 and 1260 for 6-field and 4-field 3D CRT cases, respectively. Findings from this case study involving the prostate treatments agree with those from previous studies that IMRT indeed delivers higher photon doses to locations that are away from the primary target.

Surface dose measurement in patients and physicians and effective dose estimation in patients during uterine artery embolisation

2008-06-04

Surface dose monitoring in patients and physicians during 29 uterine artery embolisation (UAE) procedures was performed using photoluminescence dosemeters and thermo-luminescence dosemeters. Organ or tissue doses were measured with an anthropomorphic phantom using UAE exposure conditions averaged from the 29 cases, and effective doses were estimated for the patient. Entrance surface dose of the patients at the maximum dose position ranged from 121.5 to 1650 mGy. Estimated doses ranged from 3.16 to 43 mGy for the ovary and from 3.8 to 51.8 mGy for the uterus. The effective dose was 1.09–14.8 mSv. Monitored doses on the body surface of physicians were relatively high in the upper arm (5.41 ± 1.52 to 163 ± 17.25 µGy) and the hand and fingers (0.85 ± 1.18 to 222 ± 16.4 µGy).

Dose conversion coefficients calculated using tomographic phantom, KTMAN-2, for X-ray examination of cardiac catheterisation

Park, S. H., Lee, J. K., Lee, C. — 2008-06-04

In this study, organ-absorbed doses and effective doses to patient during interventional radiological procedures were estimated using tomographic phantom, Korean Typical Man-2 (KTMAN-2). Four projections of cardiac catheterisation were simulated for dose calculation by Monte Carlo technique. The parameters of X-ray source and exposure conditions were obtained from literature data. Particle transport was simulated using general purposed Monte Carlo code, MCNPX 2.5.0. Organ-absorbed doses and effective doses were normalised to dose area product (DAP). The effective doses per DAP were between 0.1 and 0.5 mSv Gy^–1 per cm². The results were compared with those derived from adult stylised phantom. KTMAN-2 received up to 105% higher effective doses than stylised phantom. The dose differences were mainly caused by more realistic internal topology of KTMAN-2 compared to stylised phantom that are closely positioned organs near the heart and shift of abdominal organs to the thoracic region due to supine position. The results of this study showed that tomographic phantoms are more suitable for dose assessment of supine patients undergoing the interventional radiology. The results derived from KTMAN-2 were the first radiation dose data based on non-Caucasian individuals for interventional procedures.

The effect of field modifier blocks on the fast photoneutron dose equivalent from two high-energy medical linear accelerators

2008-06-04

High-energy linear accelerators (linacs) have several advantages, including low skin doses and high dose rates at deep-seated tumours. But, at energies more than 8 MeV, photonuclear reactions produce neutron contamination around the therapeutic beam, which may induce secondary malignancies. In spite of improvements achieved in medical linac designs, many countries still use conventional (non-intensity-modulated radiotherapy) linacs. Hence, in these conventional machines, fitting the beam over the treatment volume may require using blocks. Therefore, the effect of these devices on neutron production of linacs needs to be studied. The aim of this study was to investigate the effect of field shaping blocks on photoneutron dose in the treatment plane for two high-energy medical linacs. Two medical linacs, a Saturn 43 (25 MeV) and an Elekta SL 75/25 (18 MeV), were studied. Polycarbonate (PC) films were used to measure the fluence of photoneutrons produced by these linacs. After electrochemical etching of the PC films, the neutron dose equivalent was calculated at the isocentre and 50 cm away from the isocentre. It was noted that by increasing the distance from the centre of the X-ray beam towards the periphery, the photoneutron dose equivalent decreases rapidly for both the open and blocked fields. Increasing the energy of the photons causes an increase in the amount of photoneutron dose equivalent. At 25 MeV photon energy, the lead blocks cause a meaningful increase in the dose equivalent of photoneutrons. In this research, a 30% increase was seen in neutron dose contribution to central axis dose at the isocentre of a 25 MeV irregular field shaped by lead blocks. It is concluded that lead blocks must be considered as a source of photoneutron production when treating irregular fields with high-energy photons.

Organ and effective doses of patients arising from coronary angiography and percutaneous transluminal coronary angioplasty at two hospitals in Mashhad-Iran

Bahreyni Toossi, M. T., Zare, H., Bayani, S., Esmaili, S. — 2008-06-04

A detailed study of radiation doses received by 83 patients who underwent coronary angiography (CA) and 26 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) by the femoral route in two hospitals in Mashhad-Iran is presented. All procedures were undertaken with Siemens angioscope X-ray equipment. Thermoluminescent dosimeters (TLD-100), suitably calibrated, were used to measure the dose received at five locations on the patient's skin (on the thyroid, gonads and lens of eyes). A dose area product (DAP) meter was also used. DAP values and fluoroscopy times were recorded for each patient. The mean values for DAP were 32.47 ± 4.03 and 44.49 ± 5.64 Gy cm² for CA and PTCA, respectively. The patient dosimetry results revealed the thyroid receives the highest dose in CA and PTCA examinations. Also, in this study, DAP to effective dose conversion factors were estimated by means of a Rando phantom and the effective dose received by the patients was estimated for CA and PTCA examinations. The estimated mean values of effective dose were 6.75 ± 0.85 and 9.61 ± 1.24 mSv, respectively.

Neutron scattering in concrete and wood: Part II--oblique incidence

Facure, A., Silva, A. X., Rivera, J. C., Falcao, R. C. — 2008-06-04

The knowledge of neutron reflection coefficients is of practical interest when projecting the shielding of radiotherapy rooms, since it is known that about 75% of the neutrons at the maze entrance of these rooms are scattered neutrons. In a previous paper, the energy spectra of photoneutrons were calculated, when reflected by ordinary, high-density concrete and wood barriers, using the MCNP5 code, considering normal incidence and neutron incident energies varying between 0.1 and 10 MeV. It was found that the mean energy of the reflected neutrons does not depend on the reflection angle and that these mean energies are lower in wood and barytes concrete, compared with ordinary concrete. In the present work, the simulation of neutron reflection coefficients were completed, considering the case when these particles do not collide frontally with the barriers, which constitute the radiotherapy room walls. Some simulations were also made to evaluate how neutron equivalent doses at the position of the room door is affected when the maze walls are lined with neutron absorbing materials, such as wood itself or borated polyethylene. Finally, capture gamma rays dose at the entrance of rooms with different maze lengths were also simulated. The results were discussed in the light of the albedo concepts presented in the literature and some of these results were confronted with others, finding good agreement between them.

Variations in backscatter observed in PMMA whole-body dosimetry slab phantoms

Schwahn, S. O., Gesell, T. F. — 2008-06-04

Polymethyl methacrylate (PMMA) is a useful material for dosimetry phantoms in many ways including approximate tissue equivalence, stability, accessibility and ease of use. However, recent studies indicate that PMMA may have some unanticipated variation in backscatter from one phantom to another. While the reasons behind the variations have not been identified, it has been demonstrated that the backscatter from one phantom to another may vary by as much as 15%, resulting in a dosemeter response variation of as much as 5%. This unexpected contribution to uncertainty in delivered dose to a dosemeter may be quite large compared to the normally estimated uncertainty, potentially causing problems with calibration and performance testing. This paper includes data supporting the differences in backscatter among phantoms, and results from tests on the phantoms performed in an effort to identify possible causes.

Assessment of terrestrial gamma radiation doses for some Egyptian granite samples

El Arabi, A. M., Ahmed, N. K., Salahel Din, K. — 2008-06-04

External exposures of population to ionising radiation due to naturally occurring radionuclides in sixty-three granite samples from three different locations in south eastern desert of Egypt were considered in this article. Average outdoor gamma dose rates in air were 190, 290 and 330 nGy h^–1 for Elba, Qash Amir and Hamra Dome granites, respectively. The corresponding doses in indoor air are 270, 400 and 470 nGy h^–1, respectively. These average values give rise to annual effective dose (outdoor, indoor and in total) 0.24, 1.4 and 1.6 mSv for Elba granite. For Qash Amir and Hamra Dome granites the corresponding values were 0.35, 2 and 2.3 mSv and 0.41, 2.3 and 2.7 mSv, respectively.

Time for Unification of CT Dosimetry with Radiography and Fluoroscopy

Huda, W. — 2008-06-03

Undesirable nuclear reactions and induced radioactivity as a result of the use of the high-energy therapeutic beams generated by medical linacs

Konefal, A., Polaczek-Grelik, K., Zipper, W. — 2008-06-03

In this paper, the problem of undesirable photonuclear, electronuclear and neutron capture reactions taking place in the treatment room during emission of the typical high-energy therapeutic beams from two different medical accelerators, i.e. Primus Siemens and Varian Clinac-2300, is presented. The radioisotopes ¹⁸⁷W, ⁵⁶Mn, ²⁸Al, ⁵⁷Ni, ³⁸Cl, ⁵⁷Co and ¹⁹Au and the neutron activation of ¹H were identified as a consequence of these reactions. Moreover, the increased photon fluence rate behind the door of the accelerator bunker in the operator console room was observed during emission of the 20 MV X-rays from the Varian Clinac-2300 as well as in the case of the 15 MV X-ray beam from the Primus Siemens. No increased radiation was observed during the 6 MV X-ray beam emission. The performed measurements produced evidences on the presence of neutrons in the operator console room during emission of the 15 MV X-ray beam from the Primus Siemens as well as the 20 MV X-rays and the 22 MeV electrons from the Varian Clinac-2300 accelerator.

Dose distribution measurements and calculations for Dounreay hot particles

Aydarous, A. Sh., Charles, M. W., Darley, P. J. — 2008-06-03

Discrete fragments of irradiated nuclear fuel have been discovered on the foreshore at the Dounreay nuclear site in Scotland, offshore on the seabed and at nearby beaches which have public access. The fragments contain mainly ¹³⁷Cs and ⁹⁰Sr/⁹⁰Y and for particles recovered to date, ¹³⁷Cs activities are within the range of 10³ to 10⁸ Bq. The most active particles found at Sandside Beach contain ~3x10⁵Bq ¹³⁷Cs. Direct measurements of the spatial dose distributions from 37 fuel fragments were measured in detail for the first time using radiochromic dye film as part of a national evaluation of the associated potential radiological hazard. Monte Carlo code calculations of the doses are in good agreement with measurements, taking into account variations to be expected due to differences in shape and the increasing importance of self-absorption for the larger, more active fragments. Dose measurements provide little evidence for wide variations in the ¹³⁷Cs:⁹⁰Sr/⁹⁰Y ratio between fragments. Specific attention is given to the evaluation of skin dose, averaged over an area of 1 cm² at a depth of 0.07 mm, since this is of major radiological concern. There is no obvious dependence of skin dose on the site of origin of the fragments (foreshore, seabed or beaches) for a given ¹³⁷Cs activity level. A dose rate survey instrument (SmartION) was shown to provide a rapid and convenient method for skin dose assessment from fuel fragments in the ¹³⁷Cs activity range measured (2x10⁵ to 2x10⁷ Bq). A conversion factor multiplier of 240 can be applied to the open window SmartION scale reading to estimate the skin dose rate within ±25%.

Review of international standards for dosemeters

Behrens, R., Ambrosi, P. — 2008-06-03

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.

Case-control study of radon and lung cancer in New Jersey

2008-06-03

Radon is known to cause lung cancer in humans; however, there remain uncertainties about the effects associated with residential exposures. This case-control study of residential radon and lung cancer was conducted in five counties in New Jersey and involved 561 cases and 740 controls. A yearlong -track detector measurement of radon was completed for ~93% of all residences lived in at the time of interview (a total of 2063). While the odds ratios (ORs) for whole data were suggestive of an increased risk for exposures >75 Bq m^–3, these associations were not statistically significant. The adjusted excess OR (EOR) per 100 Bq m^–3 was –0.13 (95% CI: –0.30 to 0.44) for males, 0.29 (95% CI: –0.12 to 1.70) for females and 0.05 (95% CI: –0.14 to 0.56) for all subjects combined. An analysis of radon effects by histological type of lung cancer showed that the OR was strongest for small/oat cell carcinomas in both males and females. There was no statistical heterogeneity of radon effects by demographic factors (age at disease occurrence, education level and type of respondent). Analysis by categories of smoking status, frequency or duration did not modify the risk estimates of radon on lung cancer. The findings of this study are consistent with an earlier population-based study of radon and lung cancer among New Jersey women, and with the North American pooling of case control radon seven studies, including the previous New Jersey study. Several uncertainties regarding radon measurements and assumptions of exposure history may have resulted in underestimation of a true exposure–response relationship.

Occupational exposure to electromagnetic fields in physiotherapy departments

2008-06-03

To assess occupational exposure to electromagnetic fields, 11 microwave (MW), 4 short-wave diathermy and 15 magneto therapy devices were analysed in eight physiotherapy departments. Measurements taken at consoles and environmental mapping showed values above European Directive 2004/40/EC and ACGIH exposure limits at ~50 cm from MW applicators (2.45 GHz) and above the Directive magnetic field limit near the diathermy unit (27.12 MHz). Levels in front of MW therapy applicators decreased rapidly with distance and reduction in power; this may not always occur in work environments where nearby metal structures (chairs, couches, etc.) may reflect or perturb electromagnetic fields. Large differences in stray field intensities were found for various MW applicators. Measurements of power density strength around MW electrodes confirmed radiation fields between 30° and 150°, with a peak at 90°, in front of the cylindrical applicator and maximum values between 30° and 150° over the whole range of 180° for the rectangular parabolic applicator. Our results reveal that although most areas show substantially low levels of occupational exposure to electromagnetic fields in physiotherapy units, certain cases of over-occupational exposure limits do exist.

Assessment of the radiological hazards due to naturally occurring radionuclides in soil samples collected from the north western areas of Pakistan

Rahman, S., Matiullah, , Mujahid, S. A., Hussain, S. — 2008-06-03

²²⁶Ra, ²³²Th and ⁴⁰K were measured in soil samples, these were collected from different localities of the North West Frontier Province and Federally Administered Tribal Areas, Pakistan. In order to measure the specific activities in these samples P-type coaxial high purity germanium based gamma-ray spectrometer was used. Average values of the measured activities of ²²⁶Ra, ²³²Th and ⁴⁰K were 26 ± 11, 39 ± 17 and 485 ± 177 Bq kg^–1, respectively. Average radium equivalent activity was found to be 122 ± 42 Bq kg^–1. External and internal hazard indices were also calculated and found to be 0.33 ± 0.12 and 0.40 ± 0.14, respectively. Average effective dose received due to gamma rays was 0.34 ± 0.12 mSv y^–1. Measured natural radioactivity, hazard indices and effective doses received by the population were found within the recommended limits. The aim of this work was to make a baseline data of natural radioactive elements for the soil of the area and to assess it radiological significance if used as a building material for the construction of houses.

Evaluation and measurement of magnetic field exposure at a typical high-voltage substation and its power lines

Ozen, S. — 2008-06-03

This study presents a survey of magnetic field measurements including those resulting from 380/154 kV power substations, which play a vital role in human body biological studies. The survey was carried out in the main power substation of Antalya, Turkey, located at the suburban region of the city, under actual loads. The paper also presents the actual magnetic field strength measured near the 380/154 kV substation and power transmission lines (380 and 154 kV) connecting to the substation. Since most part of these lines pass through a residential area, they have been included in the study, and the actual magnetic field variation around them has been investigated by comparative analysis of measured data. For the occupants working at substations, occupational exposure has been analysed with actual magnetic fields at operating locations. Induced internal electric fields and current densities in the occupants' body due to exposure to external magnetic fields produced by a conventional 380/154 kV power substation have been investigated.

Measurement of natural radioactivity and dose rate assessment of terrestrial gamma radiation in the soil of southern Punjab, Pakistan

Fatima, I., Zaidi, J. H., Arif, M., Daud, M., Ahmad, S. A., Tahir, S. N. A. — 2008-06-03

Activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in soil samples collected from the most populous area of southern Punjab of Pakistan have been measured by gamma-ray spectrometry. The measured activity concentrations for these radionuclides are compared with the reported data from different other countries and it is found that measured activity concentrations are comparable with the worldwide measured average values reported by the UNSCEAR. Subsequently assessed radiological effects show that the mean radium equivalent activity (Ra_eq) is 96.7 ± 15.2 Bq kg^–1 and air absorbed dose rate (D) is 46.1 ± 7.3 nGy h^–1. The values of internal and external radiation hazard indices are found to be less than unity. The annual effective radiation dose is calculated to be 0.28 ± 0.05 mSv, which is well below the limit of 1.0 mSv y^–1 recommended by the International Commission on Radiological Protection, for the general public.

Determination of uranium, thorium and potassium activity concentrations in soil cores in Araba valley, Jordan

Abusini, M., Al-ayasreh, K., Al-Jundi, J. — 2008-06-03

Soil samples were collected from six different locations in Araba valley, situated between Aqaba port and Dead sea. The samples have been analysed by using gamma-ray spectrometry. From the measured gamma-ray spectra, activity concentrations are determined for ²³⁸U, ²³²Th and ⁴⁰K. The mean activity concentration for ²³⁸U, ²³²Th and ⁴⁰K was found to be in the range 19 ± 1.4 to 38.7 ± 3, 14.3 ± 0.8 to 35 ± 3.2 and 94 ± 18.9 to 762 ± 47.4 Bq kg^–1, respectively. These results indicate that the mean concentrations of ²³⁸U, ²³²Th and ⁴⁰K in the populated Araba valley are lower than those in other populated areas. On the other hand, the concentrations of the major oxides (Al₂O₃, SiO₂, K₂O, CaO and Fe₂O₃) in the samples were determined using wavelength dispersive X-ray fluorescence. High potassium and iron content in some samples might be attributed to the active faults, which refer to the Dead sea transform fault.

Radiation dose optimisation and risk estimation to patients and staff during hysterosalpingography

2008-06-03

Hysterosalpingography (HSG) is an efficient radiological examination for the evaluation of the female reproductive tract. However, it involves unavoidable irradiation to the ovaries of women in childbearing age. Therefore, radiation dose optimisation is required in order to reduce the probability of the associated risks. This study attempts to: measure patient and staff doses, estimate the effective dose and radiation risk for HSG using digital fluoroscopic images. Thirty-seven patients with infertility were examined using two digital X-ray machines. Thermoluminescence dosimeters (TLD) were used to measure entrance surface dose (ESD) for patients and staff during the procedure. The mean ESD and thyroid surface dose of the patient were 3.60 and 0.17 mGy, respectively, while the mean ESD for the staff was 0.18 mGy per procedure. The patient overall risk for cancer and hereditary effects is 24 x 10^–6, while the risk for the staff is negligible. HSG with fluoroscopic technique demonstrate improved dose characteristics, compared to the conventional radiographic-based technique, reducing the surface dose by a factor of 3, without compromising the diagnostic findings.

Multileaf shielding design against neutrons produced by medical linear accelerators

Rebello, W. F., Silva, A. X., Facure, A. — 2008-06-03

This work aims at presenting a study using Monte Carlo simulation of a Multileaf Shielding (MLS) System designed to be used for the protection of patients who undergo radiotherapy treatment, against undesired exposure to neutrons produced in the components of the medical linear accelerator heads. The choice of radiotherapy equipment as the subject of study fell on the Varian Clinac 2100/2300 with MLC-120 operating at 18 MeV. The general purpose Monte Carlo N-Particle radiation transport code, MCNP5, was used in the computer simulation in order to determine the ambient dose equivalent, H* (10), on several points on the patient's plane, with the equipment operation with and without the MLS. The results of the simulations showed a significant neutron dose reduction after the inclusion of the proposed shielding.

Dose from slow negative muons

Siiskonen, T. — 2008-06-03

Conversion coefficients from fluence to ambient dose equivalent, from fluence to maximum dose equivalent and quality factors for slow negative muons are examined in detail. Negative muons, when stopped, produce energetic photons, electrons and a variety of high-LET particles. Contribution from each particle type to the dose equivalent is calculated. The results show that for the high-LET particles the details of energy spectra and decay yields are important for accurate dose estimates. For slow negative muons the ambient dose equivalent does not always yield a conservative estimate for the protection quantities. Especially, the skin equivalent dose is strongly underestimated if the radiation-weighting factor of unity for slow muons is used. Comparisons to earlier studies are presented.

Influence of the rotation centre in panoramic radiography

Kaeppler, G., Buchgeister, M., Reinert, S. — 2008-06-03

The aim is to present the curve of the rotation centre in dental panoramic radiography and to examine its influence on organ doses. A screenless film was fixed between the layers of an Alderson Rando phantom in the centre of the mandible. The phantom was positioned in two different X-ray units [Scanora^® (Soredex, Helsinki, Finland) and Orthophos^® (Sirona, Bensheim, Germany)] and exposed. Organ doses and effective doses were determined. The curves of the rotation centre showed clear differences especially in the area of the parotid gland. These differences corresponded to the differences in organ doses and in effective doses (Scanora^®: 29.9 µGy; Orthophos Plus^®: 14 µGy). Artefacts might be shown (Orthophos, result of a plate osteosynthesis) or not (Scanora) due to the different rotation centres. Differences in organ doses and in image quality, e.g. artefacts, were explained with the curve of the rotation centre and beam geometry.

Monte Carlo comparison of the St Petersburg phantom with a BOMAB phantom in the HML's whole-body counter

Kramer, G. H., Capello, K., Sung, J. — 2008-06-03

Three sizes of the St Petersburg phantom have been compared to six sizes of BOMAB phantoms measured by a virtual whole-body counter similar to the one in use in the Human Monitoring Laboratory using Monte Carlo simulations. The previously published data comparing the St Petersburg Reference Man sized phantom with a similar sized Bottle Manikin Absorber Phantoms (BOMAB) phantom at 662 keV is supported; however, the simulations also show that the smaller sized St Petersburg phantoms do not agree well with smaller BOMAB phantoms. It is concluded that the St Petersburg phantoms are system dependent meaning that all sizes of the St Petersburg phantoms should be experimentally compared over a wide photon energy range against corresponding BOMAB phantoms to validate their use for calibrating whole-body counters.

Radon measurements in the Catalagzi Thermal Power Plant, Turkey

Aytekin, H., Bayata, S., Baldik, R., Celebi, N. — 2008-06-03

The Çatalagzi Thermal Power Plant (ÇTPP) (41⁰30'48.4^''N and 0.31⁰53'41.5^''E) is located at nearly 13 km North-east of Zonguldak city, which is located at the West Black Sea coast in Turkey. The middling products with high ash content of bituminous coals are used in this plant. Seasonal radon concentration measurements have been carried out by using CR-39 plastic track detectors in and around the ÇTPP. The annual average radon concentration has been found to vary from a minimum of 39.8 ± 28.9 Bq m^–3 in the ash area to a maximum of ~75.0 ± 15.7 Bq m^–3 in the service building of the power plant. The annual average radon concentration in the dwellings of the thermal power plant colony of the plant is 71.0 ± 33.4 Bq m^–3. The effective dose has been found to vary from 0.38 to 0.71 mSv y^–1 with a mean value of 0.56 mSv y^–1, which is lower than the effective dose values 3–10 mSv given as the range of action levels recommended by International Commission on Radiological Protection: Protection against radon-222 at home and at work, ICRP Publication 65 (1993).

Tritium in the urine in Finnish people

Puhakainen, M., Heikkinen, T. — 2008-06-03

Tritium in urine was analysed from 227 randomly selected Finnish adults. The people were 18 to 65 of age. Urine samples were collected over night. The mean activity concentration of tritiated water in urine was 2.5 Bq l^–1 and the maximum activity concentration 18.3 Bq l^–1. The minimum detectable activity varied from 1.5 to 2.3 Bq l^–1. Because organically bound tritium is ~10% of the total tritium, its concentration was below the detection limit and could be ignored. The mean effective dose for Finnish people from tritium was 2.4 x 10^–3 µSv y^–1.