ICRP Publication Research Articles

Dose indicator for CyberKnife image-guided radiation therapy.

The purpose of this study was to calculate dose distributions from CyberKnife image-guided radiation therapy (IGRT) for brain, H&N, lung, and pelvis treatment regions and use them to extract the corresponding effective dose and estimate-related risk. We developed a CyberKnife IGRT kV beam model in a standard treatment planning system and validated it against measurements in heterogeneous phantoms. Five brain, five head and neck, five thorax, and 10 (five male and five female) pelvis patient computed tomographies (CTs) were contoured. The dose distribution resulting from different CyberKnife IGRT protocols was calculated. From them, the effective dose was calculated according to ICRP publication Nr 103, using the average dose to contoured organs. The corresponding risk factors were calculated. Entrance surface dose (ESD) was also calculated and compared with existing data. The maximum effective dose produced by CyberKnife IGRT protocols was 0.8mSv (brain), 1.9mSv (H&N), 20.2 (pelvis), and 42.4mSv (thorax) per fraction for a risk estimate of 0.004% (brain), 0.01% (H&N), 0.1% (pelvis), and 0.2% (thorax). Calculated ESD were compatible with existing data. Dose calculation models for CyberKnife IGRT kV beams were implemented in a clinical treatment planning system and validated in water and heterogeneous phantoms. We determined the effective dose and the related risk estimate resulting from CyberKnife IGRT protocols for brain, head and neck, thorax, and pelvis cases. The effective doses calculated for CyberKnife IGRT protocols were similar to those obtained for cone beam CT protocols on conventional C-arm linear accelerators, except for extreme irradiation conditions for thorax cases (140kV X-ray tube tension).

Remarks to history of radon activity concentration metrology

Abstract The radon issue has been known worldwide for dozens of years. Many scientific (ICRP Publication No. 137), technical (ICRU Report No. 88), and legislative (Council Directive 2013/59/EURATOM (EU-BSS)) documents have been published in the last decade. More and more attention is being paid to precise quantification to determine the concentration and consequent effects of various pollutants on human health worldwide. The quality of measurement and the variety of measurement techniques increase the need to unify measurement procedures and metrology continuity. Countries around the world are beginning to unify metrological procedures for determining different quantities based on international recommendations and standards. Not only for these reasons, it became more actual a need for more accurate radon activity concentration measurement and radon metrology unification. This paper summarizes the main remarks and technical aspects to the historical development of radon metrology.

Assessment of internal radiation exposure of nuclear medicine workers using whole body gamma counter

The use of unsealed sources in nuclear medicine may cause risks of internal exposure to the staffs. From the Basic Safety Radiation Protection Regulations (BSRP 2010) under ACT 304, the radiation workers should be assessed frequently for both internal and external exposures in order to ensure the compliance of dose limit of 20 mSv/y, averaged over defined periods of 5 years. The aim of this study was to evaluate the internal exposure of radiation workers from nuclear medicine centres who might be exposed to the unsealed sources such as Tc-99m and I-131. A total of 13 radiation workers from two nuclear medicine centres were invited to perform the whole-body counting in Malaysian Nuclear Agency. Each worker was scanned using ORTEC Whole Body Counter (WBC), bed type for 2400 s counting time. The internal exposure for each radionuclide of interest was then evaluated based on the ICRP Publication 68, IAEA’s Safety Report Series No. 37 and BSRP 2010 in determining the committed effective dose. The results show that there is no internal exposure found for all monitored radiation workers, thus demonstrate that the radiation protection and safety were strictly implemented in these centres.

Internal dosimetry of uranium workers exposed during the nuclear fuel fabrication process in Spain

Workers in the Juzbado plant of ENUSA in Spain are exposed to intakes of low enriched uranium during the fabrication of nuclear fuel elements for Nuclear Power Plants. CIEMAT started in 2014 an individual monitoring program for ENUSA workers consisting in routine bioassay measurements of uranium in urine by alpha spectrometry and a methodology of dose assessment based on ICRP Publications 78/68, ISO 27048 standard and IDEAS Guidelines V2. The individual monitoring program is complemented with workplace monitoring using Static Air Samplers (SAS) at the Juzbado facility. Results of routine monitoring data of 24 h-urine samples of Juzbado workforce confirmed low level of chronic intakes of uranium oxides in the plant, combined with acute intakes associated to incidents. IMBA software allows the dose assessments in complex intake regimes of occupational inhalation of Type S uranium compounds. Uncertainties of monitoring data were evaluated using the Scattering Factor approach (ISO 27048) for the intake calculation in the defined internal exposure scenario. A total of 200 workers at risk of internal exposures in the Juzbado facility were included in routine, special, confirmatory or task-related monitoring programs established by CIEMAT in agreement with ENUSA. Annual chronic intakes were assessed for 106 workers with monitoring results above the Minimum Detectable Activity (MDA = 0.50 mBq.sample−1 of 234U, 238U and 235U). Committed Effective Doses E(50) > 1 mSv/year were initially detected in 50% of these cases. Maximum annual intakes correspond to few cases of long term exposed workers with E(50) around 5 mSv/year. The preliminary study of the impact on the dose assessment using the new uranium model according to ICRP Publication 137 is presented here, showing a reduction of E(50) around a factor of 4 for workers exposed to uranium oxides re-defined as Type M/S materials (more soluble compounds, higher urinary excretion, lower dose coefficients than Type S uranium materials defined by ICRP Publications 78/68).

Salient features of ICRP publication 142: Radiological Protection from naturally occurring radioactive material in industrial processes

Salient features of ICRP publication 142: Radiological Protection from naturally occurring radioactive material in industrial processes

Оценка потенциальных радиологических рисков населения при реализации проекта «Прорыв» Госкорпорации «Росатом». Часть 1. Рекомендации МКРЗ

The concept “radiation detriment” has been debated intensively in the pages of the ICRP Publica-tion 103 (2007), new radiation epidemiological data obtained after 2007 have also been brought into discussion. For radiation detriment calculation radiation risk models based on data of the study of Japanese cohort of atomic bombings survivors were used. Models developed for esti-mating radiation risk factors take account of gender and age at exposure. Now ICRP has estimat-ed radiation detriment in specially designed standard population by averaging the estimates based on age at exposure. The concept “radiation detriment” was developed for quantification of the overall harm to health of humans and their offspring from stochastic effects of low-level radi-ation on different parts of the body, reduction in life expectancy and reduced quality of life. In ad-dition, radiation detriment is used to assess effective dose and its standardization for radiological protection. In the paper, the concept “radiation detriment” is assessed with regard to the possibility of extending the area of its application. The applicability of technique for calculation of radiation detriment is possible to be extended with account of Russian health and statistical data, lethality fraction estimates, years of life lost, gender and age. The extended “radiation detriment” will be renamed as “radiological detriment”, that will highlight the possibility of quantifying potential harm to a specific irradiated population. The magnitude of population-based radiological detri-ment may be used not only for matching sources of ionizing radiation by their impact on the standard population, but also for estimating the level of radiological protection of the specific population. The level of radiological detriment may be used for quantification of potential harm to the public health in the implementation of the Rosatom project “Proryv”.

Paediatric Diagnostic Reference levels in low Resource Settings: A Guide for Developing Country Practitioners with excerpts from ICRP

Background: The practical implementation of Diagnostic Reference Level in paediatric imaging is a complex task due to their unique individuality in terms of high sensitivity to radiation, varying body sizes and presenting pathology. Hence, good knowledge of medical technology, skill to perform patient dosimetry and to analyze mage quality is required. Purpose: To provide a guide on the methodological requirements for the establishment of Paediatric Diagnostic Reference Levels (PiDRLs) based on the revised and updated guidelines from the current ICRP publication 135 on Diagnostic Reference Levels (DRLs). Materials and method: An extensive review of the ICRP report Publication 135 on Diagnostic Reference levels in medical imaging with a focus on paediatric imaging and other related studies were undertaken. Results: The ICRP report 135 updates and refines the recommendations of 2001. It highlights that the application of DRLs in paediatrics alone is not sufficient for the optimization of protection. Image quality must be evaluated. Quantities used for DRLs should be appropriate to the imaging modality being evaluated, assess the amount of ionizing radiation applied to perform a medical imaging task, and be measured directly. For interventional procedures, the complexity of the procedure may be considered in setting DRLs. DRLs shall not be used for individual patients or as trigger (alert or alarm) levels for individual patients. Appropriate weight bands (generally with 5 or 10 kg intervals) are recommended for establishing paediatric DRLs and should be promoted. Conclusion: The amount of radiation used for examinations of children can vary tremendously due to great variation in patient size and weight from neonates to adult-sized adolescents. This variation in patient radiation dose is appropriate. However, variation in patient doses due to inappropriate technique or failure to child-size the imaging protocol is not appropriate. This forms the basis of the new ICRP guideline and should form the basis of developing PiDRLs.

ICRP Publication 142: Radiological Protection from Naturally Occurring Radioactive Material (NORM) in Industrial Processes.

The purpose of this publication is to provide guidance on radiological protection in industries involving naturally occurring radioactive material (NORM). These industries may give rise to multiple hazards and the radiological hazard is not necessarily dominant. The industries are diverse and may involve exposure of people and the environment where protective actions need to be considered. In some cases, there is a potential for significant routine exposure of workers and members of the public if suitable control measures are not considered. Releases of large volumes of NORM may also result in detrimental effects on the environment from radiological and non-radiological constituents. However, NORM industries present no real prospect of a radiological emergency leading to tissue reactions or immediate danger for life. Radiological protection in industries involving NORM can be appropriately addressed on the basis of the principles of justification of the actions taken and optimisation of protection using reference levels. An integrated and graded approach is recommended for the protection of workers, the public, and the environment, where consideration of non-radiological hazards is integrated with radiological hazards, and the approach to protection is optimised (graded) so that the use of various radiological protection programme elements is consistent with the hazards while not imposing unnecessary burdens. For workers, the approach starts with characterisation of the exposure situation, and integration, as necessary, of specific radiological protective actions to complement the protection strategy already in place or planned to manage other workplace hazards. According to the characteristics of the exposure situation and the magnitude of the hazards, a relevant reference level should be selected and appropriate collective or individual protective actions taken. Exposure to radon is also treated using a graded approach, based first on application of typical radon prevention and mitigation techniques, as described in <italic>Publication 126</italic>. A similar approach should be implemented for public exposure through the control of discharges, wastes, and residues after characterisation of the situation. If the protection of non-human species is warranted, it should be dealt with after an assessment of radiological exposure appropriate for the circumstances, taking into account all hazards and impacts. This should include identification of exposed organisms in the environment, and use relevant derived consideration reference levels to inform decisions on options for control of exposure.

A Scalable Database of Organ Doses for Common Diagnostic Fluoroscopy Procedures of Children: Procedures of Historical Practice for Use in Radiation Epidemiology Studies.

Assessment of health effects from low-dose radiation exposures in patients undergoing diagnostic imaging is an active area of research. High-quality dosimetry information pertaining to these medical exposures is generally not readily available to clinicians or epidemiologists studying radiation-related health risks. The purpose of this study was to provide methods for organ dose estimation in pediatric patients undergoing four common diagnostic fluoroscopy procedures: the upper gastrointestinal (UGI) series, the lower gastrointestinal (LGI) series, the voiding cystourethrogram (VCUG) and the modified barium swallow (MBS). Abstracted X-ray film data and physician interviews were combined to generate procedure outlines detailing X-ray beam projections, imaged anatomy, length of X-ray exposure, and presence and amount of contrast within imaged anatomy. Monte Carlo radiation transport simulations were completed for each of the four diagnostic fluoroscopy procedures across the 162-member (87 males and 75 females) University of Florida/National Cancer Institute pediatric phantom library, which covers variations in both subject height and weight. Absorbed doses to 28 organs, including the active marrow and bone endosteum, were assigned for all 162 phantoms by procedure. Additionally, we provide dose coefficients (DCs) in a series of supplementary tables. The DCs give organ doses normalized to procedure-specific dose metrics, including: air kerma-area product (µGy/mGy · cm2), air kerma at the reference point (µGy/µGy), number of spot films (SF) (µGy/number of SFs) and total fluoroscopy time (µGy/s). Organs accumulating the highest absorbed doses per procedure were as follows: kidneys between 0.9-25.4 mGy, 1.1-16.6 mGy and 1.1-9.7 mGy for the UGI, LGI and VCUG procedures, respectively, and salivary glands between 0.2-3.7 mGy for the MBS procedure. Average values of detriment-weighted dose, a phantom-specific surrogate for the effective dose based on ICRP Publication 103 tissue-weighting factors, were 0.98 mSv, 1.16 mSv, 0.83 mSv and 0.15 mSv for the UGI, LGI, VCUG and MBS procedures, respectively. Scalable database of organ dose coefficients by patient sex, height and weight, and by procedure exposure time, reference point air kerma, kerma-area product or number of spot films, allows clinicians and researchers to compute organ absorbed doses based on their institution-specific and patient-specific dose metrics. In addition to informing on patient dosimetry, this work has the potential to facilitate exposure assessments in epidemiological studies designed to investigate radiation-related risks.

ICRP Publication 140: Radiological Protection in Therapy with Radiopharmaceuticals.

Radiopharmaceuticals are increasingly used for the treatment of various cancers with novel radionuclides, compounds, tracer molecules, and administration techniques. The goal of radiation therapy, including therapy with radiopharmaceuticals, is to optimise the relationship between tumour control probability and potential complications in normal organs and tissues. Essential to this optimisation is the ability to quantify the radiation doses delivered to both tumours and normal tissues. This publication provides an overview of therapeutic procedures and a framework for calculating radiation doses for various treatment approaches. In radiopharmaceutical therapy, the absorbed dose to an organ or tissue is governed by radiopharmaceutical uptake, retention in and clearance from the various organs and tissues of the body, together with radionuclide physical half-life. Biokinetic parameters are determined by direct measurements made using techniques that vary in complexity. For treatment planning, absorbed dose calculations are usually performed prior to therapy using a trace-labelled diagnostic administration, or retrospective dosimetry may be performed on the basis of the activity already administered following each therapeutic administration. Uncertainty analyses provide additional information about sources of bias and random variation and their magnitudes; these analyses show the reliability and quality of absorbed dose calculations. Effective dose can provide an approximate measure of lifetime risk of detriment attributable to the stochastic effects of radiation exposure, principally cancer, but effective dose does not predict future cancer incidence for an individual and does not apply to short-term deterministic effects associated with radiopharmaceutical therapy. Accident prevention in radiation therapy should be an integral part of the design of facilities, equipment, and administration procedures. Minimisation of staff exposures includes consideration of equipment design, proper shielding and handling of sources, and personal protective equipment and tools, as well as education and training to promote awareness and engagement in radiological protection. The decision to hold or release a patient after radiopharmaceutical therapy should account for potential radiation dose to members of the public and carers that may result from residual radioactivity in the patient. In these situations, specific radiological protection guidance should be provided to patients and carers.

Dosimetric Impact of a New Computational Voxel Phantom Series for the Japanese Atomic Bomb Survivors: Pregnant Females.

An important cohort of the atomic bomb survivors are women who were pregnant when exposed to the photon and neutron fields at both Hiroshima and Nagasaki, as well as their children who were exposed in utero. Estimates of organ dose to the developing fetus allow for the development of dose-dependent and gestational age-dependent models of deterministic (e.g., organ malformation) and stochastic (e.g., leukemia) risk of in utero exposure. To date, both the 1986 and 2002 dosimetry systems at the Radiation Effects Research Foundation have utilized the uterine wall in the non-pregnant adult female as a dose surrogate for individual fetal organs and tissues. Here we present a new J45 (Japanese 1945) series of high-resolution phantoms of the adult pregnant female at 8-, 15-, 25- and 38-weeks post-conception. These models, which were derived from the University of Florida (UF) series of ICRP Publication 89 compliant reference phantoms, have been rescaled to approximate the pregnant mother using 1945 Japanese morphometry data. Fetal and maternal organ doses were estimated by computationally exposing the pregnant female phantom series to DS02 free-in-air photon and neutron fluences at three distances from the hypocenter at both Hiroshima and Nagasaki under frontal (AP) and isotropic (ISO) particle incidence. As for the fetal organ doses, our results indicate that the uterine wall of the non-pregnant female generally underestimates fetal organ dose within the pregnant female. The magnitude of these differences varies with both radiation type and irradiation geometry, with the smallest differences (5-7%) seen for ISO photon fields and the largest differences (20-30%) seen for AP neutron fields. Significant discrepancies were seen in fetal brain dose and its uterine wall surrogate, particularly for photon AP fields (ratio of uterine wall to brain dose varied from 0.9 to 1.3) and neutron AP fields (dose ratios from 0.75 to 2.0). As for the maternal organ doses, the use of organ doses in a non-pregnant female was shown, in general, to overestimate the corresponding organ doses in the pregnant female, with greater deviations seen at later stages of pregnancy (12-16% for AP photons and 44-53% for AP neutrons). The one exception was the uterine wall dose in pregnancy which was seen to be underestimated by that in the non-pregnant female phantom, particularly for ISO and AP neutron fields. These results demonstrate that the J45 pregnant female phantom series offers the opportunity for significant improvements in both fetal and maternal organ dose assessment within this unique cohort of the atomic bomb survivors.

Dosimetric dependence of ocular structures on eye size and shape for external radiation fields of electrons, photons, and neutrons

The dosimetric dependence of ocular structures on eye size and shape was investigated within the standard ICRP Publication 116 irradiation geometries. A realistic transport geometry was constructed by inserting a scalable and deformable stylised eye model developed in our previous study within the head of the ICRP Publication 110 adult male reference computational phantom. Beam irradiations of external electrons, photons, and neutrons on this phantom were simulated using the Monte Carlo radiation transport code PHITS in the geometries of AP, RLAT, PA and ROT. Absorbed doses in ocular structures such as ciliary body, retina, and optic nerves were computed as well as that in lens. A clear dosimetric dependence of ocular structures on eye size and shape was observed for external electrons while only a small dependence was seen for external photons and neutrons. Difference of the tendency was attributed to their depth-dose distributions where spread dose distributions were created by photons and neutrons while more concentrated distributions were created by external electrons.

Estimating radiation protection factor (RPF) values for a simple surrogate vehicle using the MCNP6.1 code

Computational and experimental estimates of radiation protection factor (RPF) values are of significant interest to various defense-related organizations. Values of the operational quantity of ambient dose equivalent were computed, using version 6.1 of the Monte Carlo N-Particle® code (MCNP6.1), for 25 photon energies and 53 neutrons energies. Energy-dependent values for absorbed dose at a 10-mm depth in the 30-cm-diameter ICRU tissue-equivalent sphere, D*(10), were estimated using the kerma approximation for photon (MCNP F6:p tally) and neutron (MCNP F6:n tally) radiation fields, and then transformed to fluence-to-ambient dose equivalent conversion coefficients, H*(10)/ϕ, using appropriate quality factors, Q, and radiation fluences. MCNP6.1-computed values of H*(10)/ϕ were compared with tabulated values from ICRP Publication 74. The published conversion coefficients for photon radiation fields were within the error bounds of all MCNP6.1-calculated values. For neutron fields, the computed and published conversion coefficients agreed within calculated error bounds for neutron energies of 100 keV and above, while responses to neutron fields below 100 keV exhibited the same shape and were consistent with the kerma approximation applied in the computational model. The MCNP6.1 models were then modified to simulate the same radiation fields, but H*(10)/ϕ conversion coefficients were calculated in the shielded environment of a surrogate vehicle (steel cube)—in keeping with historical and recent studies—and the ratios of shielded and unshielded vehicle response functions were expressed as energy-dependent RPF values. The MCNP6.1-computed neutron RPF values were compared with two prior experimental studies involving a mono-energetic neutron source and a high-yield, short-duration fission neutron spectrum and found to agree within the uncertainty of the experimentally-measured values. Limitations of the computed RPF values are discussed.

210Po as a source of natural radioactivity in cigarettes distributed in the Philippines

Abstract The natural radioactive nuclides especially 210 Po, are volatilized at the temperature (600 – 800 °C) of a burning cigarette and are taken into the human body. Therefore, analysis of natural radioactivity of 210 Po in cigarettes and the effective dose to smokers should be evaluated. The activity concentration of 210 Po in sixteen brands of Philippine cigarettes was measured by alpha spectrometry, and estimation of effective dose of 210 Po to smokers was performed. The activity concentration of 210 Po in cigarettes distributed in the Philippines ranged from 5.5 to 17.8 mBq/cigarette and the mean value of their activity concentrations was 12.0 mBq/cigarette. The mean value of annual effective doses of 210 Po to smokers obtained from these activity concentrations was 0.021 mSv/y, which was lower than the reference level (1-20 mSv/y) for existing situation in ICRP Publication 103.

Evaluation of equivalent dose to eye lens through dose equivalent Hp(3)

PurposeIndividual dosimetry allows to quantify doses from ionizing radiation of exposed workers. Scientific and epidemiological evidences highlight the need for adequate measures for a greater protection of the eye and a reduction in annual doses. ICRP Publication 103, illustrating the operational dose quantity Hp(d) for the individual monitoring, proposes a depth d = 3 mm for eye lens monitoring, indicating that even the Hp(0.07) can be used. In this study, it was investigated if there are differences in the evaluation of the equivalent dose to eye lens (Hlens) using Hp(3) or Hp(0.07). Materials and methodsA slab phantom calibration was performed by an Accredited Calibration Laboratory in terms of Hp(3) and Hp(0.07) using ext-rad TLD-100 (LiF:Mg,Ti) dosimeters. Hp(0.07) and Hp(3) were measured for 26 exposed workers to assess Hlens. The measuring took place monthly in 2017 to obtain both semestral and annual doses. ResultsHlens(0.07) was always smaller than Hlens(3). However, the differences were not statistically significant (Mann-Whitney test, p > 0.05) for both semestral and annual doses. The percentage differences were 7 ± 3%, 6 ± 3% and 7 ± 2% for I semester, II semester and whole year, respectively. The mean underestimation index <10%, intra-class correlation coefficient >0.99, coefficient of variation <3% and the excellent correlation (R2 ≈ 0.999) for both semestral and annual doses highlighted that Hp(0.07) can be used to evaluate Hlens instead of Hp(3). ConclusionsNo statistical evidence was found that the use of Hp(0.07) underestimates the equivalent dose to eye lens obtained through Hp(3).

Development of a reference framework to assess stylized human intrusion scenarios using GENII Version 2 considering design features of planned near-surface disposal facility in Korea

Abstract A standard form of six stylized human intrusion scenarios for a near-surface disposal facility (e.g. the planned Korean repository, Gyeongju Phase II) is proposed through re-categorization of totally thirty-one past cases reported in public literature. A reference assessment framework for inadvertent human intrusion is newly developed using GENII Version 2 conforming to the ICRP Publication 60 and thereafter. Calculated dose from the assessment framework is verified by comparing with hand calculation results for simplified model equations independently derived. Results from GENII Version 2 and 1.485 show inevitable differences, which is mainly attributed to the difference in the external dose assessment model. If intake dose coefficients in GENII Version 1.485 are modified, the difference can be reduced but still exist to an extent. Through deterministic and probabilistic sensitivity analysis, most affecting four parameters are derived and uncertainties of the parameters are quantified. It is expected that the reference assessment framework together with representative stylized scenarios can be used to do a human intrusion impact assessment for a specific repository using site-specific information. Especially, the past practice of human intrusion impact assessment using GENII Version 1.485 with or without modification may be replaced with the new assessment framework developed in this study.

Fluence-to-effective dose conversion coefficients for male astronauts

The problem of the reliable estimation of astronauts’ radiation exposure doses in deep space is very important and relevant in connection with the accepted space research programmes. The effective dose value based on ICRP Publication 103 presents too conservative an estimate of an astronaut’s radiation risk. A more realistic dose can be calculated on the basis of relationships between the radiation quality factor and linear energy transfer or linear energy or Z*2/β2, according to the NASA concept. In addition, it is reasonable to use a set of tissue weighting coefficients (normalised relative detriments) that have been averaged over a cohort of working age males similar to the male astronaut cohort. The closest to the male astronauts is the NASA cohort of males aged 30–60 years who have never smoked. The fluence-to-effective dose equivalent conversion coefficients calculated specially for male astronauts are compared. Different approaches to radiation risk estimation for astronauts are discussed.

Uranium isotopes concentrations in surface water samples for Al-Manathera and Al-Heerra regions of An-Najaf, Iraq

In this work, the concentrations of natural uranium, uranium isotopes, and the annual effective dose in the surface water for both of Al-Manathera and Al-Heerra regions of An-Najaf, Iraq were determined using a solid state, nuclear track detector, type (CR-39). The results show that the average of uranium concentrations in Al-Manathera and Al-Heerra regions were 1.75 ± 0.202 µg/l and 1.07 ± 0.152 µg/l respectively. The average of activities of 238U, 235U and 234U in Al-Manathera were in 6.48 ± 0.250, 0.100 ± 0.011 and 2.18 ± 0.252 Bq/l, while in Al-Heerra, they were 1.27 ± 0.188, 0.061 ± 0.008 and 1.33 ± 0.189 Bq/l, respectively. The total average of the annual effective dose of natural uranium in all water samples to the adult members of the population for both of Al-Manathera and Al-Heerra regions were 0.152 ± 0.017 µSv/y and 0.093 ± 0.012 µSv/y respectively. In addition, the outcomes demonstrate that uranium levels in the samples of water from Al-Manathera region were far toxic than the samples of Al-Heerra region, as they included uranium levels and total annual effective dose in all water samples of water that comply with the worldwide limits that are approved by International Commission on Radiological Protection (ICRP Publication, Ottawa, 21:1–3; ICRP, Recommendations of the International Commission on Radiological Protection, ICRP Publication, Ottawa, 1990 and Pergamum Press, Oxford; ICRP, Annals of the ICRP. ICRP publication 65, Pergamum Press, Oxford, 1993) which states that safe limits are (1.9 µg/L and 1 mSv/y) respectively. For that reason, one may conclude that the radioactive isotopes are not considered dangerous in case humans consumed it.

NEUROENDOCRINE EFFECTS OF PRENATAL IRRADIATION FROM RADIOACTIVE IODINE (review).

Neuroendocrine effects of the prenatal radiation exposure from radioactive iodine in an event of nuclear power reactor accidents are a key issue in the field of radiation medicine and radiation safety because of a dramatic radiosensitivity of the developing organism. Review of contemporary epidemiological, clinical and experimental data on neuroendocrine effects of prenatal exposure to 131I. Search in the PubMed/MEDLINE and Google Scholar abstract databases, along with a manual search for the relevant data sources. Estimated absorbed doses of intrauterine thyroid irradiation from radioactive iodine were obtained based on ICRP Publication 88, both with estimates of effective radiation doses on embryo and fetus, and estimates of the brain equivalent doses upon exposure in utero. The latter ones are subject to updating. The evidence-based data has been presented regarding a radiation-associated reduction of head and chest circumference at birth, as well as a radiation-associated excess of goiter with large thyroid nodules, and possibly of thyroid cancer after a prenatal exposure to 131I radionuclides. Data on intrauterine brain damage are controversial, but most researchers share the view that there are cognitive and emotional-behavioral disorders due to prenatal and postnatal irradiation and psy- chosocial impacts. Incidence increase of non-cancerous endocrine disorders and degenerative vascular disease of retina was noted. An experimental model of intrauterine irradiation from 131I on Wistar rats was for the first time ever created, extrapolating the radioneuroembryological effects in rats to individuals prenatally exposed after the Chornobyl disaster. Late neuropsychiatric and endocrine effects may be resulted from the relatively short-term impact of ionizing radiation at a level previously been considered safe. The necessity of neuropsychiatric and endocrinological monitoring of individuals exposed prenatally to ionizing radiation after the Chornobyl catastrophe throughout their life is substantiated. Experimental animal studies are a key direction in the further research of radiation effects, especially associated with low radiation doses. Further experimental and clinical neuroradiobio- logical studies aimed at exploration of the effect of ionizing radiation on hippocampal neurogenesis are most rele- vant nowadays.

Cataractogenic load - A concept to study the contribution of ionizing radiation to accelerated aging in the eye lens.

Ionizing radiation (IR) damages DNA and other macromolecules, including proteins and lipids. Most cell types can repair DNA damage and cycle continuously their macromolecules as a mechanism to remove defective proteins and lipids. In those cells that lack nuclei and other organelles, such as lens fiber cells and mammalian erythrocytes, IR-induced damage to macromolecules is retained because they cannot be easily replenished. Whilst the life span for an erythrocyte is several months, the life span of a human lens is decades. There is very limited turnover in lens macromolecules, therefore the aging process greatly impacts lens structure and function over its lifetime. The lens is a tissue where biomolecular longevity, lifelong retention of its components and continued growth are integral to its homeostasis. These characteristics make the lens an excellent model to study the contribution of retained macromolecular damage over time. Epidemiological data have revealed a significant association between exposure to IR, the loss of lens optical function and the formation of cataracts (cataractogenesis) later in life. Lifestyle, genetic and environmental factors all contribute to cataractogenesis due to their effect on the aging process. Cataract is an iconic age-related disease in humans. IR is a recognised cause of cataract and the occupational lens dose limit is reduced from 150 to 20 mGy / year averaged over 5 years (ICRP Publication 118). Understanding the effects of low dose IR on the lens and its role in cataractogenesis is therefore very important. So we redefine "cataractogenic load" as a term to account for the combined lifestyle, genetic and environmental processes that increase biomolecular damage to lens macromolecules leading to cataract formation. These processes weaken metabolic defenses, increase post-translational protein modifications, and alter the lipid structure and content of the lens. IR exposure is a significant insult to the lens because of free radical generation and the ensuing oxidative stress. We support the concept that damage caused by IR compounds the aging process by increasing the cataractogenic load, hereby accelerating lens aging and its loss of function.