Cataracts among Chernobyl Clean-up Workers: Implications Regarding Permissible Eye Exposures

Somatic Variants in the Human Lens Epithelium: A Preliminary Assessment

Purpose

We hypothesize that somatic mutations accumulate in cells of the human lens and may contribute to the development of cortical or posterior sub-capsular cataracts. Here, we used a Next-generation sequencing (NGS) strategy to screen for low-allelic frequency variants in DNA extracted from human lens epithelial samples.

Methods

Next-Generation sequencing of 151 cancer-related genes (WUCaMP2 panel) was performed on DNA extracted from post-mortem or surgical specimens obtained from 24 individuals. Usually, pairwise comparisons were made between two or more ocular samples from the same individual, allowing putative somatic variants detected in lens samples to be differentiated from germline variants.

Results

Use of a targeted hybridization approach enabled high sequence coverage (>1000-fold) of the WUCaMP2 genes. In addition to high-frequency variants (corresponding to homozygous or heterozygous SNPs and Indels), somatic variants with allelic frequencies of 1-4% were detected in the lens epithelial samples. The presence of one such variant, a T > C point substitution at position 32907082 in BRCA2, was verified subsequently using droplet digital PCR.

Conclusions

Low-allelic fraction variants are present in the human lens epithelium, at frequencies consistent with the presence of millimeter-sized clones.

The effects of simulating a realistic eye model on the eye dose of an adult male undergoing head computed tomography

In head computed tomography, radiation upon the eye lens (as an organ with high radiosensitivity) may cause lenticular opacity and cataracts. Therefore, quantitative dose assessment due to exposure of the eye lens and surrounding tissue is a matter of concern. For this purpose, an accurate eye model with realistic geometry and shape, in which different eye substructures are considered, is needed. To calculate the absorbed radiation dose of visual organs during head computed tomography scans, in this study, an existing sophisticated eye model was inserted at the related location in the head of the reference adult male phantom recommended by the International Commission on Radiological Protection (ICRP). Then absorbed doses and distributions of energy deposition in different parts of this eye model were calculated and compared with those based on a previous simple eye model. All calculations were done using the Monte Carlo code MCNP4C for tube voltages of 80, 100, 120 and 140 kVp. In spite of the similarity of total dose to the eye lens for both eye models, the dose delivered to the sensitive zone, which plays an important role in the induction of cataracts, was on average 3% higher for the sophisticated model as compared to the simple model. By increasing the tube voltage, differences between the total dose to the eye lens between the two phantoms decrease to 1%. Due to this level of agreement, use of the sophisticated eye model for patient dosimetry is not necessary. However, it still helps for an estimation of doses received by different eye substructures separately.

The risk of cataractogenesis after gamma knife radiosurgery: a nationwide population based case-control study

Background

Medical radiation is considered a factor responsible for cataractogenesis. However, the incidence of this ophthalmologic complication resulting from gamma knife radiosurgery (GKRS) has not yet been reported. The present study aimed to determine the risk of cataractogenesis associated with radiation exposure from GKRS.

Methods

This study used information from a random sample of one million persons enrolled in the nationally representative Taiwan National Health Insurance Research Database. The GK group consisted of patients who underwent GKRS between 2000 and 2009. The non-GK group was composed of subjects who had never undergone GKRS, but who were matched with the case group for time of enrollment, age, sex, history of coronary artery disease, hypertension, and diabetes.

Results

There were 277 patients in the GK group and 2770 matched subjects in the non-GK group. The GK group had a higher overall incidence of cataracts (10.11% vs. 7.26%; crude hazard ratio [cHR], 1.59; 95% CI, 1.07–2.36; adjusted hazard ratio [aHR], 1.25; 95% CI, 0.82–1.90) than the non-GK group. Patients who had undergone computed tomography and/or cerebral angiography (CT/angio) studies had a higher risk of developing cataracts than those who did not (10.82% vs. 6.64%; cHR, 1.74; 95% CI, 1.31–2.30; aHR, 1.65; 95% CI, 1.22–2.23). The age group between 30 and 50 years had the highest risk of cataractogenesis in both the GK and CT/angio groups (cHR, 3.50; 95% CI, 1.58–7.72; aHR, 2.43; 95% CI, 1.02–5.81; cHR, 2.96; 95% CI, 1.47–5.99; aHR, 2.27; 95% CI, 1.05–4.93, respectively).

Conclusions

Radiation exposure due to GKRS and CT/angio study may be independently associated with increased risk of cataractogenesis. We suggest routine dosimetry measurement of eye lens and proper protection for patients with benign lesions during GKRS. Regular follow-up imaging studies should avoid the use of CT/angio, and particular care should be taken in the 30–50-year-old age group, due to their significantly increased risk of cataract formation.

HIGHLIGHTS OF THE RUSSIAN HEALTH STUDIES PROGRAM AND UPDATED RESEARCH FINDINGS

Recognized for conducting cutting-edge science in the field of radiation health effects research, the Department of Energy's (DOE) Russian Health Studies Program has continued to generate excitement and enthusiasm throughout its 23-year mission to assess worker and public health risks from radiation exposure resulting from nuclear weapons production activities in the former Soviet Union. The three goals of the Program are to: (1) clarify the relationship between health effects and chronic, low-to-medium dose radiation exposure; (2) estimate the cancer risks from exposure to gamma, neutron, and alpha radiation; and (3) provide information to the national and international organizations that determine radiation protection standards and practices. Research sponsored by DOE's Russian Health Studies Program is conducted under the authority of the Joint Coordinating Committee for Radiation Effects Research (JCCRER), a bi-national committee representing Federal agencies in the United States and the Russian Federation. Signed in 1994, the JCCRER Agreement established the legal basis for the collaborative research between USA and Russian scientists to determine the risks associated with working at or living near Russian former nuclear weapons production sites. The products of the Program are peer-reviewed publications on cancer risk estimates from worker and community exposure to ionizing radiation following the production of nuclear weapons in Russia. The scientific return on investment has been substantial. Through 31 December 2015, JCCRER researchers have published 299 peer-reviewed publications. To date, the research has focused on the Mayak Production Association (Mayak) in Ozersk, Russia, which is the site of the first Soviet nuclear weapons production facility, and people in surrounding communities along the Techa River. There are five current projects in the Russian Health Studies Program: two radiation epidemiology studies; two historical dose reconstruction studies and a worker biorepository. National and international standard-setting organizations use cancer risk estimates computed from epidemiological and historical dose reconstruction studies to validate or revise radiation protection standards. An overview of the most important research results will be presented.

Assessment of the occupational eye lens dose for clinical staff in interventional radiology, cardiology and neuroradiology

In accordance with recommendations by the International Commission on Radiological Protection, the current European Basic Safety Standards has adopted a reduced occupational eye lens dose limit of 20 mSv yr^-1. The radiation safety implications of this dose limit is of concern for clinical staff that work with relatively high dose x-ray angiography and interventional radiology. Presented in this work is a thorough assessment of the occupational eye lens dose based on clinical measurements with active personal dosimeters worn by staff during various types of procedures in interventional radiology, cardiology and neuroradiology. Results are presented in terms of the estimated equivalent eye lens dose for various medical professions. In order to compare the risk of exceeding the regulatory annual eye lens dose limit for the widely different clinical situations investigated in this work, the different medical professions were separated into categories based on their distinct work pattern: staff that work (a) regularly beside the patient, (b) in proximity to the patient and (c) typically at a distance from the patient. The results demonstrate that the risk of exceeding the annual eye lens dose limit is of concern for staff category (a), i.e. mainly the primary radiologist/cardiologist. However, the results also demonstrate that the risk can be greatly mitigated if radiation protection shields are used in the clinical routine. The results presented in this work cover a wide range of clinical situations, and can be used as a first indication of the risk of exceeding the annual eye lens dose limit for staff at other medical centres.

Organ and effective dose reduction for region-of-interest (ROI) CBCT and fluoroscopy

In some medical-imaging procedures using CBCT and fluoroscopy, it may be needed to visualize only the center of the field-of-view with optimal quality. To reduce the dose to the patient as well as enable increased contrast in the region of interest (ROI) during CBCT and fluoroscopy procedures, a 0.7 mm thick Cu ROI attenuator with a circular aperture 12% of the FOV was used. The aim of this study was to quantify the dose-reduction benefit of ROI imaging during a typical CBCT and interventional fluoroscopy procedures in the head and torso. The Toshiba Infinix C-Arm System was modeled in BEAMnrc/EGSnrc with and without the ROI attenuator. Patient organ and effective doses were calculated in DOSXYZnrc/EGSnrc Monte-Carlo software for CBCT and interventional procedures. We first compared the entrance dose with and without the ROI attenuator on a 20 cm thick solid-water block. Then we simulated a CBCT scan and an interventional fluoroscopy procedure on the head and torso with and without an ROI attenuator. The results showed that the entrance-surface dose reduction in the solid water is about 85.7% outside the ROI opening and 10.5% in the ROI opening. The results showed a reduction in most organ doses of 45%-70% and in effective dose of 46%-66% compared to the dose in a CBCT scan and in an interventional procedure without the ROI attenuator. This work provides evidence of substantial reduction of organ and effective doses when using an ROI attenuator during CBCT and fluoroscopic procedures.

[Risk of senile cataract among nuclear industry workers]

AIM

to assess the relative risk (RR) of senile cataract in a cohort of workers occupationally exposed to external gamma-rays over a long time period.

MATERIAL AND METHODS

The RR of cataract development was studied in a cohort of nuclear workers that were first employed in 1948-1982 and followed up till the end of 2008 (n=22,377; females, 25.4%). The mean age at initial employment was 24.9 years. The mean cumulative gamma-ray dose was 0.54 Sv in males and 0.44 Sv in females. The analysis performed with EPICURE software provided RR estimates for cataract incidence in relation to a number of non-radiation and radiation factors.

RESULTS

The RR of senile cataract increased with the attained age of the workers. The RR was significantly higher in males during the 2006-2008 period as compared to the 1996-2005 period. The RR was significantly higher in workers that were diagnosed with glaucoma and high myopia as compared to those that were not. The risk of senile cataract increased with the external gamma-ray dose and was the highest in workers who had formerly been exposed to doses above 2.00 Sv. The RR of senile cataract showed no dependency on sex, age at initial employment, smoking status, alcohol consumption, or diabetes mellitus.

CONCLUSION

The incidence of senile cataract in the cohort under study was found to depend on both non-radiation and radiation factors.

Hand Surgery and Fluoroscopic Eye Radiation Dosage: A Prospective Pilot Comparison of Large Versus Mini C-Arm Fluoroscopy Use

Background: The purpose of this study is to (1) perform a prospective pilot comparison of the impact of large versus mini C-arm fluoroscopy on resultant eye radiation exposure and (2) test the hypothesis that the use of either modality during routine hand surgery does not exceed the current recommended limits to critical eye radiation dosage. Methods: Over a 12-month period, eye radiation exposure was prospectively measured by a board-certified hand surgeon using both large and mini C-arm fluoroscopy. For each modality, accumulated eye radiation dosage was measured monthly, while fluoroscopic radiation output was recorded, including total exposure time and dose rate. Results: A total of 58 cases were recorded using large C-arm and 25 cases using mini C-arm. Between the 2 groups, there was not a significant difference with total exposure time (P = .88) and average dose rate per case (P = .10). With the use of either modality, average monthly eye radiation exposure fell within the undetectable range (<30 mrem), significantly less than the current recommended limit of critical eye radiation (167 mrem/month). Conclusions: The impact of various fluoroscopic sources on eye radiation exposure remains relatively unexplored. In this study, the minimal detectable eye radiation dosages observed in both groups were reliably consistent. Our findings suggest that accumulated eye radiation dosage, from the use of either fluoroscopic modality, does not approach previously reported levels of critical radiation loads.

Monte Carlo study of the scattered radiation field near the eyes of the operator in interventional procedures

Interventional radiology and cardiology guarantee high benefits for patients, but are known to be associated with a high level of radiation exposure of medical staff. The recently suggested decrease of the annual dose limit for the eye lens, from 150 to 20 mSv, caused a need for a reconsideration of practices ensuring sufficient protection for the lens of the eyes of medical staff. In such context the study of the scattered radiation around the operator's head could help in finding the best solutions to be adopted for the ceiling-suspended shield and lead glasses in the most common situations in interventional practices. MCNPX Monte Carlo code was employed with anthropomorphic mathematical phantoms to simulate interventional practice projections. For each projection the effect of changing selected parameters on the evaluated scattered radiation towards the operator's head has been calculated. The variety of modelled situations provides plentiful material regarding the spatial distribution of the scattered radiation, useful to improve eye lens radiation protection, such as the following:  (a) Glasses, which provide shielding from both lateral and bottom-up scattered radiation, can reduce by ten times the exposure to the most exposed eyes;  (b) The ceiling-suspended shield offers valuable protection, but such effectiveness can diminish by 90% if the shielding is not correctly positioned;  (c) The transition from femoral to radial access usually intensifies the scattered radiation toward the operator head (a factor of 1.5 for AP projection), but for RAO projections, a reduction of the order by two to three times, in the case of radial access, can be seen, due to the protection provided by the image receptor. The detailed fluence outcomes show that there is a preferential direction of the impinging scattered radiation that should be considered when radiation protection options are evaluated or when a dedicated eye lens dosemeter is used for monitoring.

ON-FIELD EVALUATION OF OPERATOR LENS PROTECTIVE DEVICES IN INTERVENTIONAL RADIOLOGY

The recent publication of the Euratom Directive 2013/59, adopting the reduction of eye lens dose limits from 150 to 20 mSv y^-1, calls for the development of new tools and methodologies for evaluating the eye lens dose absorbed by the medical staff involved in interventional radiology practices. Moreover, the effectiveness of the protective devices, like leaded glasses, which can be employed for radiation protection purposes, must be tested under typical exposure scenarios. In this work, eye lens dose measurements were carried out on an anthropomorphic phantom simulating a physician bound to perform standard interventional neuroradiology angiographic procedures. The correlation between eye lens doses, in terms of Hp(0.07), and the equivalent dose [again in terms of Hp(0.07)] monthly measured with thermoluminescent dosemeters placed above the lead apron at the chest level was studied, in the presence and in the absence of different types of leaded glasses.

Risk of Cataract Incidence in a Cohort of Mayak PA Workers following Chronic Occupational Radiation Exposure

This is the first study of cataract incidence in a cohort of Mayak Production Association workers first employed at one of the main facilities in 1948-1982 and followed up till the end of 2008 (22,377 workers). Principal advantages of the study are the large size of the cohort, long-term follow-up and sufficient statistical power, available results of annual eye examinations over the entire follow-up period and detailed information on non-radiation confounders. Individual measured doses from external γ-rays and neutrons used in the analyses were provided by the Mayak Worker Dosimetry System 2008 (MWDS-2008). Relative risk (RR) and excess relative risk (ERR) per unit dose (Gy) were calculated based on maximum likelihood using the AMFIT module of the EPICURE software. The RR of cataract incidence was found to be the highest in workers exposed at doses above 2.0 Gy. A significant linear association of cataract incidence with cumulative dose from external γ-rays was found with ERR/Gy equal to 0.28 (95% confidence intervals: 0.20, 0.37). The results obtained varied slightly with inclusion of additional adjustments for non-radiation factors (smoking index, hypertension, glaucoma and body mass index). Adjusting for the dose from neutrons gave a considerable increase in ERR/Gy for cataract incidence.

InterCardioRisk: a novel online tool for estimating doses of ionising radiation to occupationally-exposed medical staff and their associated health risks

Those working in interventional cardiology and related medical procedures are potentially subject to considerable exposure to x-rays. Two types of tissue of particular concern that may receive considerable doses during such procedures are the lens of the eye and the brain. Ocular radiation exposure results in lens changes that, with time, may progress to partial or total lens opacification (cataracts). In the early stages, such opacities do not result in visual disability; the severity of such changes tends to increase progressively with dose and time until vision is impaired and cataract surgery is required. Scattered radiation doses to the eye lens of an interventional cardiologist in typical working conditions can exceed 34 μGy min^-1 in high-dose fluoroscopy modes and 3 μGy per image during image acquisition (instantaneous rate values) when radiation protection tools are not used. A causal relation between exposure to ionising radiation and increased risk of brain and central nervous system tumours has been shown in a number of studies. Although absorbed doses to the brain in interventional cardiology procedures are lower than those to the eye lens by a factor between 3.40 and 8.08 according to our simulations, doses to both tissues are among the highest occupational radiation doses documented for medical staff whose work involves exposures to x-rays. We present InterCardioRisk, a tool featuring an easy-to-use web interface that provides a general estimation of both cumulated absorbed doses experienced by medical staff exposed in the interventional cardiology setting and their estimated associated health risks. The tool is available at http://intercardiorisk.creal.cat.

Doses for post-Chernobyl epidemiological studies: are they reliable?

On 26 April 2016, thirty years will have elapsed since the occurrence of the Chernobyl accident, which has so far been the most severe in the history of the nuclear reactor industry. Numerous epidemiological studies were conducted to evaluate the possible health consequences of the accident. Since the credibility of the association between the radiation exposure and health outcome is highly dependent on the adequacy of the dosimetric quantities used in these studies, this paper makes an effort to overview the methods used to estimate individual doses and the associated uncertainties in the main analytical epidemiological studies (i.e. cohort or case-control) related to the Chernobyl accident. Based on the thorough analysis and comparison with other radiation studies, the authors conclude that individual doses for the Chernobyl analytical epidemiological studies have been calculated with a relatively high degree of reliability and well-characterized uncertainties, and that they compare favorably with many other non-Chernobyl studies. The major strengths of the Chernobyl studies are: (1) they are grounded on a large number of measurements, either performed on humans or made in the environment; and (2) extensive effort has been invested to evaluate the uncertainties associated with the dose estimates. Nevertheless, gaps in the methodology are identified and suggestions for the possible improvement of the current dose estimates are made.

[Effects on health of the Chernobyl accident: 30 years on]

This paper reflects the current state of research into the short- and long-term effects on health in the former Soviet Union and Europe of the nuclear accident in Chernobyl. It discusses the latest results of epidemiological studies and presents future research perspectives.

Ionizing Radiation Doses Detected at the Eye Level of the Primary Surgeon During Orthopaedic Procedures

OBJECTIVES

To evaluate the ionizing radiation dose received by the eyes of orthopaedic surgeons during various orthopaedic procedures. Secondary objective was to compare the ionizing radiation dose received between differing experience level.

DESIGN

Prospective comparative study between January 2013 and May 2014.

SETTING

Westmead Hospital, a Level 1 Trauma Centre for Greater Western Sydney.

PARTICIPANTS

A total of 26 surgeons volunteered to participate within the study.

INTERVENTION

Experience level, procedure performed, fluoroscopy time, dose area product, total air kerma, and eye dose received was recorded. Participants were evaluated on procedure and experience level.

MAIN OUTCOME MEASUREMENTS

Radiation dose received at eye level by the primary surgeon during an orthopaedic procedure.

RESULTS

Data from a total of 131 cases was recorded and included for analysis. The mean radiation dose detected at the eye level of the primary surgeon was 0.02 mSv (SD = 0.05 mSv) per procedure. Radiation at eye level was only detected in 31 of the 131 cases. The highest registered dose for a single procedure was 0.31 mSv. Femoral nails and pelvic fixation procedures had a significantly higher mean dose received than other procedure groups (0.04 mSv (SD = 0.07 mSv) and 0.04 mSv (SD = 0.06 mSv), respectively). Comparing the eye doses received by orthopaedic consultants and trainees, there was no significant difference between the 2 groups.

CONCLUSIONS

The risk of harmful levels of radiation exposure at eye level to orthopaedic surgeons is low. This risk is greatest during insertion of femoral intramedullary nails and pelvic fixation, and it is recommended that in these situations, surgeons take all reasonable precautions to minimize radiation dose. The orthopaedic trainees in this study were not subjected to higher doses of radiation than their consultant trainers. On the basis of these results, most of the orthopaedic surgeons remain well below the yearly radiation dose of 20 mSv as recommended by the International Commission on Radiological Protection.

30 years After the Chernobyl Nuclear Accident: Time for Reflection and Re-evaluation of Current Disaster Preparedness Plans

It has been 30 years since the worst accident in the history of the nuclear era occurred at the Chernobyl power plant in Ukraine close to densely populated urban areas. To date, epidemiological studies reported increased long-term risks of leukemia, cardiovascular diseases, and cataracts among cleanup workers and of thyroid cancer and non-malignant diseases in those exposed as children and adolescents. Mental health effects were the most significant public health consequence of the accident in the three most contaminated countries of Ukraine, Belarus, and the Russian Federation. Timely and clear communication with affected populations emerged as one of the main lessons in the aftermath of the Chernobyl nuclear accident.

The Risk of Cataract among Survivors of Childhood and Adolescent Cancer: A Report from the Childhood Cancer Survivor Study

With therapeutic successes and improved survival after a cancer diagnosis in childhood, increasing numbers of cancer survivors are at risk of subsequent treatment-related morbidities, including cataracts. While it is well known that the lens of the eye is one of the most radiosensitive tissues in the human body, the risks associated with radiation doses less than 2 Gy are less understood, as are the long- and short-term cataract risks from exposure to ionizing radiation at a young age. In this study, we followed 13,902 five-year survivors of childhood cancer in the Childhood Cancer Survivor Study cohort an average of 21.4 years from the date of first cancer diagnosis. For patients receiving radiotherapy, lens dose (mean: 2.2 Gy; range: 0-66 Gy) was estimated based on radiotherapy records. We used unconditional multivariable logistic regression models to evaluate prevalence of self-reported cataract in relationship to cumulative radiation dose both at five years after the initial cancer diagnosis and at the end of follow-up. We modeled the radiation effect in terms of the excess odds ratio (EOR) per Gy. We also analyzed cataract incidence starting from five years after initial cancer diagnosis to the end of follow-up using Cox regression. A total of 483 (3.5%) cataract cases were identified, including 200 (1.4%) diagnosed during the first five years of follow-up. In a multivariable logistic regression model, cataract prevalence at the end of follow-up was positively associated with lens dose in a manner consistent with a linear dose-response relationship (EOR per Gy = 0.92; 95% CI: 0.65-1.20). The odds ratio for doses between 0.5 and 1.5 Gy was elevated significantly relative to doses <0.5 Gy (OR = 2.2; 95% CI: 1.3-3.7). The results from this study indicate a strong association between ocular exposure to ionizing radiation and long-term risk of pre-senile cataract. The risk of cataract increased with increasing exposure, beginning at lens doses as low as 0.5 Gy. Our findings are in agreement with a growing body of evidence of an elevated risk for lens opacities in populations exposed to doses of ionizing radiation below the previously suggested threshold level of 2 Gy.

Occupational eye lens doses in interventional cardiology. A multicentric study

New European regulation regarding radiological protection of workers and more specifically the new occupational dose limit for the eye lens recently reduced to 20 mSv yr(-1) may affect interventional cardiologists. This paper presents a set of measurements of occupational doses performed in five interventional cardiology centres and then compared with the new dose limit. The measurement of occupational doses was performed over the apron at chest level using electronic dosemeters recording H p(10). In one of the centres, scatter dose at goggles was also measured with optically stimulated luminescence dosemeters calibrated in terms of H p(0.07). An average H p(10) over the apron of 46 μSv/procedure was measured for cardiologists. Lower doses were noted in other professionals like second cardiologists, nurses or anaesthetists. Procedures for valvular and other structural heart diseases involved the highest occupational doses, averaging over 100 μSv/procedure. Important differences in occupational doses among centres may be indicative of different radiation protection habits. The new occupational dose limit for the eye lens is likely to be exceeded by those among the interventionalists who do not use protection tools (ceiling suspended screen and/or goggles) even with standard workloads.

Measurement of occupational doses of ionising radiation to the lens of the eyes of interventional radiologists

Currently, there exists no standardised method for monitoring radiation doses to the eye lens. This investigation aimed to determine the optimum method for monitoring the eye doses for interventional radiologists. Three interventional radiologists were issued with a series of dosimeters to wear during their routine work. These dosimeters were worn at defined positions on the body and the absorbed dose to each position was measured. It was confirmed that the dose received to the thyroid collar followed an apparently well-defined relationship to the dose recorded on the forehead, which is representative of the dose to the lens of the eye. It was also confirmed that, as hypothesised, the dose to the left eye was universally greater than to the right, although by varying factors. It was concluded that the use of dosimeters attached to the inside arms of protective eyewear is the optimum solution for eye lens dosimetry. It was also concluded that, when used with a dose conversion factor which corroborates existing literature, dosimeters attached to the outside of a thyroid collar yield sufficiently accurate results for use in routine dosimetry programmes.

Lens of the eye dose calculation for neuro-interventional procedures and CBCT scans of the head

The aim of this work is to develop a method to calculate lens dose for fluoroscopically-guided neuro-interventional procedures and for CBCT scans of the head. EGSnrc Monte Carlo software is used to determine the dose to the lens of the eye for the projection geometry and exposure parameters used in these procedures. This information is provided by a digital CAN bus on the Toshiba Infinix C-Arm system which is saved in a log file by the real-time skin-dose tracking system (DTS) we previously developed. The x-ray beam spectra on this machine were simulated using BEAMnrc. These spectra were compared to those determined by SpekCalc and validated through measured percent-depth-dose (PDD) curves and half-value-layer (HVL) measurements. We simulated CBCT procedures in DOSXYZnrc for a CTDI head phantom and compared the surface dose distribution with that measured with Gafchromic film, and also for an SK150 head phantom and compared the lens dose with that measured with an ionization chamber. Both methods demonstrated good agreement. Organ dose calculated for a simulated neuro-interventional-procedure using DOSXYZnrc with the Zubal CT voxel phantom agreed within 10% with that calculated by PCXMC code for most organs. To calculate the lens dose in a neuro-interventional procedure, we developed a library of normalized lens dose values for different projection angles and kVp's. The total lens dose is then calculated by summing the values over all beam projections and can be included on the DTS report at the end of the procedure.

[Radiation protection in interventional radiology]

The application of ionizing radiation in medicine seems to be a safe procedure for patients as well as for occupational exposition to personnel. The developments in interventional radiology with fluoroscopy and dose-intensive interventions require intensified radiation protection. It is recommended that all available tools should be used for this purpose. Besides the options for instruments, x‑ray protection at the intervention table must be intensively practiced with lead aprons and mounted lead glass. A special focus on eye protection to prevent cataracts is also recommended. The development of cataracts might no longer be deterministic, as confirmed by new data; therefore, the International Commission on Radiological Protection (ICRP) has lowered the threshold dose value for eyes from 150 mSv/year to 20 mSv/year. Measurements show that the new values can be achieved by applying all X‑ray protection measures plus lead-containing eyeglasses.

EURADOS strategic research agenda: vision for dosimetry of ionising radiation

Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises-based on input from EURADOS Working Groups (WGs) and Voting Members-five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org).

Fitness costs of increased cataract frequency and cumulative radiation dose in natural mammalian populations from Chernobyl

A cataract is a clouding of the lens that reduces light transmission to the retina, and it decreases the visual acuity of the bearer. The prevalence of cataracts in natural populations of mammals, and their potential ecological significance, is poorly known. Cataracts have been reported to arise from high levels of oxidative stress and a major cause of oxidative stress is ionizing radiation. We investigated whether elevated frequencies of cataracts are found in eyes of bank voles Myodes glareolus collected from natural populations in areas with varying levels of background radiation in Chernobyl. We found high frequencies of cataracts in voles collected from different areas in Chernobyl. The frequency of cataracts was positively correlated with age, and in females also with the accumulated radiation dose. Furthermore, the number of offspring in female voles was negatively correlated with cataract severity. The results suggest that cataracts primarily develop as a function of ionizing background radiation, most likely as a plastic response to high levels of oxidative stress. It is therefore possible that the elevated levels of background radiation in Chernobyl affect the ecology and fitness of local mammals both directly through, for instance, reduced fertility and indirectly, through increased cataractogenesis.

A New Era of Low-Dose Radiation Epidemiology

The last decade has introduced a new era of epidemiologic studies of low-dose radiation facilitated by electronic record linkage and pooling of cohorts that allow for more direct and powerful assessments of cancer and other stochastic effects at doses below 100 mGy. Such studies have provided additional evidence regarding the risks of cancer, particularly leukemia, associated with lower-dose radiation exposures from medical, environmental, and occupational radiation sources, and have questioned the previous findings with regard to possible thresholds for cardiovascular disease and cataracts. Integrated analysis of next generation genomic and epigenetic sequencing of germline and somatic tissues could soon propel our understanding further regarding disease risk thresholds, radiosensitivity of population subgroups and individuals, and the mechanisms of radiation carcinogenesis. These advances in low-dose radiation epidemiology are critical to our understanding of chronic disease risks from the burgeoning use of newer and emerging medical imaging technologies, and the continued potential threat of nuclear power plant accidents or other radiological emergencies.

Dosimetry Support of the Ukrainian-American Case-control Study of Leukemia and Related Disorders Among Chornobyl Cleanup Workers

This paper describes dose reconstruction for a joint Ukrainian-American case-control study of leukemia that was conducted in a cohort of 110,645 male Ukrainian cleanup workers of the Chornobyl (Chernobyl) accident who were exposed to various radiation doses over the 1986-1990 time period. Individual bone-marrow doses due to external irradiation along with respective uncertainty distributions were calculated for 1,000 study subjects using the RADRUE method, which employed personal cleanup history data collected in the course of an interview with the subject himself if he was alive or with two proxies if he was deceased. The central estimates of the bone-marrow dose distributions range from 3.7 × 10(-5) to 3,260 mGy, with an arithmetic mean of 92 mGy. The uncertainties in the individual stochastic dose estimates can be approximated by lognormal distributions; the average geometric standard deviation is 2.0.

Impact of radiation protection means on the dose to the lens of the eye while handling radionuclides in nuclear medicine

The human eye lens appears to be more radiosensitive than previously assumed. The reduction of the limit for the dose to the lens of the eye to 20 mSv per year has been passed in the current Euratom Directives (2013). Therefore, in this work the impact of laboratory glasses and X-ray protective goggles was investigated and reciprocal attenuation factors (i.e. transmission factors) for different nuclides (Tc-99m, I-131, Y-90, F-18 and Ga-68) were determined. The radionuclides in typical geometry (syringe, applicator) were positioned at a distance of 50 cm to the eyes of four Alderson-Head-Phantoms. Different dosemeters measuring H_p(3) respective H_p(0.07) were fixed to the eyes of the phantoms, either behind the glasses or without any protection means, respectively. The mean reciprocal attenuation factors were determined to be between unity for F-18 and I-131 using laboratory glasses (no attenuation effect) and < 0.01 for Y-90 using X-ray protective goggles. All other results were between these extremes. It has been shown, that prospective doses to the lens of the eye can be reduced significantly by using appropriate radiation protection means, especially for those dose-relevant beta radiation emitting nuclides such as Y-90.

Eye lens monitoring for interventional radiology personnel: dosemeters, calibration and practical aspects of H p (3) monitoring. A 2015 review

A thorough literature review about the current situation on the implementation of eye lens monitoring has been performed in order to provide recommendations regarding dosemeter types, calibration procedures and practical aspects of eye lens monitoring for interventional radiology personnel. Most relevant data and recommendations from about 100 papers have been analysed and classified in the following topics: challenges of today in eye lens monitoring; conversion coefficients, phantoms and calibration procedures for eye lens dose evaluation; correction factors and dosemeters for eye lens dose measurements; dosemeter position and influence of protective devices. The major findings of the review can be summarised as follows: the recommended operational quantity for the eye lens monitoring is H p (3). At present, several dosemeters are available for eye lens monitoring and calibration procedures are being developed. However, in practice, very often, alternative methods are used to assess the dose to the eye lens. A summary of correction factors found in the literature for the assessment of the eye lens dose is provided. These factors can give an estimation of the eye lens dose when alternative methods, such as the use of a whole body dosemeter, are used. A wide range of values is found, thus indicating the large uncertainty associated with these simplified methods. Reduction factors from most common protective devices obtained experimentally and using Monte Carlo calculations are presented. The paper concludes that the use of a dosemeter placed at collar level outside the lead apron can provide a useful first estimate of the eye lens exposure. However, for workplaces with estimated annual equivalent dose to the eye lens close to the dose limit, specific eye lens monitoring should be performed. Finally, training of the involved medical staff on the risks of ionising radiation for the eye lens and on the correct use of protective systems is strongly recommended.

Eye lens dose in interventional cardiology

The ICRP has recently recommended reducing the occupational exposure dose limit for the lens of the eye to 20 mSv y(-1), averaged over a period of 5 y, with no year exceeding 50 mSv, instead of the current 150 mSv y(-1). This reduction will have important implications for interventional cardiology and radiology (IC/IR) personnel. In this work, lens dose received by a staff working in IC is studied in order to determine whether eye lens dose monitoring or/and additional radiological protection measures are required. Eye lens dose exposure was monitored in 10 physicians and 6 nurses. The major IC procedures performed were coronary angiography and percutaneous transluminal coronary angioplasty. The personnel were provided with two thermoluminescent dosemeters (TLDs): one calibrated in terms of Hp(3) located close to the left ear of the operator and a whole-body dosemeter calibrated in terms of Hp(10) and Hp(0.07) positioned on the lead apron. The estimated annual eye lens dose for physicians ranged between 8 and 60 mSv, for a workload of 200 procedures y(-1). Lower doses were collected for nurses, with estimated annual Hp(3) between 2 and 4 mSv y(-1). It was observed that for nurses the Hp(0.07) measurement on the lead apron is a good estimate of eye lens dose. This is not the case for physicians, where the influence of both the position and use of protective devices such as the ceiling shield is very important and produces large differences among doses both at the eyes and on the thorax. For physicians, a good correlation between Hp(3) and dose area product is shown.

Radiation dose response estimation with emphasis on low dose range using restricted cubic splines: application to all solid cancer mortality data, 1950-2003, in atomic bomb survivors

Using the all solid cancer mortality data set of the Life Span Study (LSS) cohort from 1950 to 2003 (LSS Report 14) data among atomic bomb survivors, excess relative risk (ERR) statistical analyses were performed using the second degree polynomial and the threshold and restricted cubic spline (RCS) dose response models. For the RCS models with 3 to 7 knots of equally spaced percentiles with margins in the dose range greater than 50 mGy, the dose response was assumed to be linear at less than 70 to 90 mGy. Due to the skewed dose distribution of atomic bomb survivors, the current knot system for the RCS analysis results in a detailed depiction of the dose response as less than approximately 0.5 Gy. The 6 knot RCS models for the all-solid cancer mortality dose response of the whole dose or less than 2 Gy were selected with the AIC model selection criterion and fit significantly better (p < 0.05) than the linear (L) model. The usual RCS includes the L-global model but not the quadratic (Q) nor linear-quadratic (LQ) global models. The authors extended the RCS to include L or LQ global models by putting L or LQ constraints on the cubic spline in the lower and upper tails, and the best RCS model selected with AIC criterion was the usual RCS with L-constraints in both the lower and upper tails. The selected RCS had a linear dose-response model in the lower dose range (i.e., < 0.2-0.3 Gy) and was compatible with the linear no-threshold (LNT) model in this dose range. The proposed method is also useful in describing the dose response of a specific cancer or non-cancer disease incidence/mortality.

Influence of dosemeter position for the assessment of eye lens dose during interventional cardiology

The equivalent dose limit for the eye lens for occupational exposure recommended by the ICRP has been reduced to 20 mSv y(-1) averaged over defined periods of 5 y, with no single year exceeding 50 mSv. The compliance with this new requirement could not be easy in some workplace such as interventional radiology and cardiology. The aim of this study is to evaluate different possible approaches in order to have a good estimate of the eye lens dose during interventional procedures. Measurements were performed with an X-ray system Philips Allura FD-10, using a PMMA phantom to simulate the patient scattered radiation and a Rando phantom to simulate the cardiologist. Thermoluminescence (TL) whole-body and TL eye lens dosemeters together with Philips DoseAware active dosemeters were located on different positions of the Rando phantom to estimate the eye lens dose in typical cardiology procedures. The results show that, for the studied conditions, any of the analysed dosemeter positions are suitable for eye lens dose assessment. However, the centre of the thyroid collar and the left ear position provide a better estimate. Furthermore, in practice, improper use of the ceiling-suspended screen can produce partial protection of some parts of the body, and thus large differences between the measured doses and the actual exposure of the eye could arise if the dosemeter is not situated close to the eye.

Application of the ELDO approach to assess cumulative eye lens doses for interventional cardiologists

In preparation of a large European epidemiological study on the relation between eye lens dose and the occurrence of lens opacities, the European ELDO project focused on the development of practical methods to estimate retrospectively cumulative eye lens dose for interventional medical professionals exposed to radiation. The present paper applies one of the ELDO approaches, correlating eye lens dose to whole-body doses, to assess cumulative eye lens dose for 14 different Finnish interventional cardiologists for whom annual whole-body dose records were available for their entire working period. The estimated cumulative left and right eye lens dose ranged from 8 to 264 mSv and 6 to 225 mSv, respectively. In addition, calculations showed annual eye lens doses sometimes exceeding the new ICRP annual limit of 20 mSv. The work also highlights the large uncertainties associated with the application of such an approach proving the need for dedicated dosimetry systems in the routine monitoring of the eye lens dose.

Current discussions of DDREF, cataracts, circulatory diseases and dose limits

Although more than a century of radiation research has provided a lot of insight into radiation risk, there are still fields that need clarification. This is particularly true for the low dose range, meaning doses up to ∼100 mSv. One can detect biological effects in that dose range, but it is unclear whether these biological effects like mutations or chromosomal aberrations translate into health effects like cancer, cataracts or circulatory diseases. Thus, for radiation protection purposes, assumptions have to made that must be reappraised on the basis of new findings from time to time. Affected by new insights are currently the DDREF (dose and dose-rate effectiveness factor), cataracts and circulatory diseases. If the new findings are very convincing, dose limits have to be changed at short notice. If there are only weak indications, stability of the radiation protection system is more important than changing limits all the time.

Editor's choice--Angulation of the C-arm during complex endovascular aortic procedures increases radiation exposure to the head

OBJECTIVES/BACKGROUND

The increased complexity of endovascular aortic repair necessitates longer procedural time and higher radiation exposure to the operator, particularly to exposed body parts. The aims were to measure directly exposure to radiation of the bodies and heads of the operating team during endovascular repair of thoracoabdominal aortic aneurysms (TAAA), and to identify factors that may increase exposure.

METHODS

This was a single-centre prospective study. Between October 2013 and July 2014, consecutive elective branched and fenestrated TAAA repairs performed in a hybrid operating room were studied. Electronic dosimeters were used to measure directly radiation exposure to the primary (PO) and assistant (AO) operator in three different areas (under-lead, over-lead, and head). Fluoroscopy and digital subtraction angiography (DSA) acquisition times, C-arm angulation, and PO/AO height were recorded.

RESULTS

Seventeen cases were analysed (Crawford II-IV), with a median operating time of 280 minutes (interquartile range 200-330 minutes). Median age was 76 years (range 71-81 years); median body mass index was 28 kg/m(2) (25-32 kg/m(2)). Stent-grafts incorporated branches only, fenestrations only, or a mixture of branches and fenestrations. A total of 21 branches and 38 fenestrations were cannulated and stented. Head dose was significantly higher in the PO compared with the AO (median 54 μSv [range 24-130 μSv] vs. 15 μSv [range 7-43 μSv], respectively; p = .022), as was over-lead body dose (median 80 μSv [range 37-163 μSv] vs. 32 μSv [range 6-48 μSv], respectively; p = .003). Corresponding under-lead doses were similar between operators (median 4 μSv [range 1-17 μSv] vs. 1 μSv [range 1-3 μSv], respectively; p = .222). Primary operator height, DSA acquisition time in left anterior oblique (LAO) position, and degrees of LAO angulation were independent predictors of PO head dose (p < .05).

CONCLUSIONS

The head is an unprotected area receiving a significant radiation dose during complex endovascular aortic repair. The deleterious effects of exposure to this area are not fully understood. Vascular interventionalists should be cognisant of head exposure increasing with C-arm angulation, and limit this manoeuvre.

Evaluation of occupational and patient radiation doses in orthopedic surgery

This study intends to measure the radiation dose to patients and staff during (i) Dynamic Hip Screw (DHS) and (ii) Dynamic Cannula Screw (DCS) and to evaluate entrance surface Air kerma (ESAK) dose and organ doses and effective doses. Calibrated Thermoluminescence dosimeters (TLD-GR200A) were used. The mean patients' doses were 0.46mGy and 0.07mGy for DHS and DCS procedures, respectively. The mean staff doses at the thyroid and chest were 4.69mGy and 1.21mGy per procedure. The mean organ and effective dose for patients and staff were higher in DHS compared to DCS. Orthopedic surgeons were exposed to unnecessary radiation doses due to the lack of protection measures. The radiation dose per hip procedure is within the safety limit and less than the previous studies.