10 CFR 20.1201 - Occupational dose limits for adults.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false Occupational dose limits for adults. 20.1201 Section 20.1201 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose... surveys or other radiation measurements for the purpose of demonstrating compliance with the occupational...

10 CFR 20.1201 - Occupational dose limits for adults.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false Occupational dose limits for adults. 20.1201 Section 20.1201 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose... surveys or other radiation measurements for the purpose of demonstrating compliance with the occupational...

OCCUPATIONAL RADIATION DOSES TO OPERATORS PERFORMING FLUOROSCOPICALLY-GUIDED PROCEDURES

PubMed Central

Kim, Kwang Pyo; Miller, Donald L.; de Gonzalez, Amy Berrington; Balter, Stephen; Kleinerman, Ruth A.; Ostroumova, Evgenia; Simon, Steven L.; Linet, Martha S.

2012-01-01

In the past 30 years, the numbers and types of fluoroscopically-guided (FG) procedures have increased dramatically. The objective of the present study is to provide estimated radiation doses to physician specialists, other than cardiologists, who perform FG procedures. We searched Medline to identify English-language journal articles reporting radiation exposures to these physicians. We then identified several primarily therapeutic FG procedures that met specific criteria: well-defined procedures for which there were at least five published reports of estimated radiation doses to the operator, procedures performed frequently in current medical practice, and inclusion of physicians from multiple medical specialties. These procedures were percutaneous nephrolithotomy (PCNL), vertebroplasty, orthopedic extremity nailing for treatment of fractures, biliary tract procedures, transjugular intrahepatic portosystemic shunt creation (TIPS), head/neck endovascular therapeutic procedures, and endoscopic retrograde cholangiopancreatography (ERCP). We abstracted radiation doses and other associated data, and estimated effective dose to operators. Operators received estimated doses per patient procedure equivalent to doses received by interventional cardiologists. The estimated effective dose per case ranged from 1.7 – 56μSv for PCNL, 0.1 – 101 μSv for vertebroplasty, 2.5 – 88μSv for orthopedic extremity nailing, 2.0 – 46μSv for biliary tract procedures, 2.5 – 74μSv for TIPS, 1.8 – 53μSv for head/neck endovascular therapeutic procedures, and 0.2 – 49μSv for ERCP. Overall, mean operator radiation dose per case measured over personal protective devices at different anatomic sites on the head and body ranged from 19 – 800 (median = 113) μSv at eye level, 6 – 1180 (median = 75)μSv at the neck, and 2 – 1600 (median = 302) μSv at the trunk. Operators’ hands often received greater doses than the eyes, neck or trunk. Large variations in operator doses

Increased occupational radiation doses: nuclear fuel cycle.

PubMed

Bouville, André; Kryuchkov, Victor

2014-02-01

The increased occupational doses resulting from the Chernobyl nuclear reactor accident that occurred in Ukraine in April 1986, the reactor accident of Fukushima that took place in Japan in March 2011, and the early operations of the Mayak Production Association in Russia in the 1940s and 1950s are presented and discussed. For comparison purposes, the occupational doses due to the other two major reactor accidents (Windscale in the United Kingdom in 1957 and Three Mile Island in the United States in 1979) and to the main plutonium-producing facility in the United States (Hanford Works) are also covered but in less detail. Both for the Chernobyl nuclear reactor accident and the routine operations at Mayak, the considerable efforts made to reconstruct individual doses from external irradiation to a large number of workers revealed that the recorded doses had been overestimated by a factor of about two.Introduction of Increased Occupational Exposures: Nuclear Industry Workers. (Video 1:32, http://links.lww.com/HP/A21).

Estimation of an Occupational Choice Model when Occupations Are Misclassified

ERIC Educational Resources Information Center

Sullivan, Paul

2009-01-01

This paper develops an empirical occupational choice model that corrects for misclassification in occupational choices and measurement error in occupation-specific work experience. The model is used to estimate the extent of measurement error in occupation data and quantify the bias that results from ignoring measurement error in occupation codes…

On the feasibility of utilizing active personal dosimeters worn on the chest to estimate occupational eye lens dose in x-ray angiography.

PubMed

Omar, Artur; Marteinsdottir, Maria; Kadesjö, Nils; Fransson, Annette

2015-06-01

The International Commission on Radiological Protection (ICRP) has recommended that the occupational dose limit to the eye lens be substantially reduced. To ensure compliance with these recommendations, monitoring of the occupational eye lens dose is essential in certain hospital work environments. For assessment of the eye lens dose it is recommended to use a supplementary dosimeter placed at a position adjacent to the eye(s). Wearing a dosimeter at eye level can, however, be impractical and distributing and managing additional dosimeters over long periods of time is cumbersome and costly for large clinical sites. An attractive alternative is to utilize active personal dosimeters (APDs), which are routinely used by clinical staff for real-time monitoring of the personal dose equivalent rate (H(p)(10)). In this work, a formalism for the determination of eye lens dose from the response of such APD's worn on the chest is proposed and evaluated. The evaluation is based on both phantom and clinical measurements performed in an x-ray angiography suite for interventional cardiology. The main results show that the eye lens dose to the primary operator and to the assisting clinical staff can be conservatively estimated from the APD response as D(eye)(conductor) = 2.0 APD chest and D(eye)(assisting) = 1.0 APD chest, respectively. However, care should be exercised for particularly short assisting staff and if radiation protection shields are misused. These concerns can be greatly mitigated if the clinical staff are provided with adequate radiation protection training.

Occupational radiation procedures and doses in South Korean dentists.

PubMed

Kim, Yoon-Ji; Cha, Eun Shil; Lee, Won Jin

2016-10-01

Dentistry is among the occupations involving chronic exposure to ionizing radiation. Although several cohort studies on medical radiation workers have been conducted in some countries, only a few epidemiological studies on dentists have been performed to examine occupational radiation exposure worldwide. The aim of this study was to investigate occupational characteristics and radiation exposures in South Korean dentists. A total of 658 dentists were surveyed from April 2012 to May 2013, and survey data were linked with dosimetry data from the National Dose Registry. Multiple linear regression analysis was used to identify the relationship between demographic or occupational factors and individual radiation doses. Of the dentists sampled, 78% were men, 51% were younger than age 40, and 61% began employment after 2000. The most frequent procedures performed by dentists were panoramic radiography, followed by intraoral and portable dental radiography. Male dentists were more frequently involved in radiation procedures, and a higher proportion of male than female dentists wore a lead apron for diagnostic radiology. The average annual effective dose was 0.18 mSv for male and 0.13 mSv for female dentists. Female dentists working in provincial areas had significantly higher average annual and cumulative effective doses than those in metropolitan areas. The cumulative effective doses were significantly greater for older dentists, those who entered the field in the 1990s, and those with longer employment duration. Our findings provided detailed information on work practices, number of procedures performed on a weekly basis, and occupational radiation doses, which enabled in-depth evaluation of occupational radiation exposure and work status among dentists. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Occupancy estimation and the closure assumption

USGS Publications Warehouse

Rota, Christopher T.; Fletcher, Robert J.; Dorazio, Robert M.; Betts, Matthew G.

2009-01-01

1. Recent advances in occupancy estimation that adjust for imperfect detection have provided substantial improvements over traditional approaches and are receiving considerable use in applied ecology. To estimate and adjust for detectability, occupancy modelling requires multiple surveys at a site and requires the assumption of 'closure' between surveys, i.e. no changes in occupancy between surveys. Violations of this assumption could bias parameter estimates; however, little work has assessed model sensitivity to violations of this assumption or how commonly such violations occur in nature. 2. We apply a modelling procedure that can test for closure to two avian point-count data sets in Montana and New Hampshire, USA, that exemplify time-scales at which closure is often assumed. These data sets illustrate different sampling designs that allow testing for closure but are currently rarely employed in field investigations. Using a simulation study, we then evaluate the sensitivity of parameter estimates to changes in site occupancy and evaluate a power analysis developed for sampling designs that is aimed at limiting the likelihood of closure. 3. Application of our approach to point-count data indicates that habitats may frequently be open to changes in site occupancy at time-scales typical of many occupancy investigations, with 71% and 100% of species investigated in Montana and New Hampshire respectively, showing violation of closure across time periods of 3 weeks and 8 days respectively. 4. Simulations suggest that models assuming closure are sensitive to changes in occupancy. Power analyses further suggest that the modelling procedure we apply can effectively test for closure. 5. Synthesis and applications. Our demonstration that sites may be open to changes in site occupancy over time-scales typical of many occupancy investigations, combined with the sensitivity of models to violations of the closure assumption, highlights the importance of properly addressing

Estimation of Radiation Dose for a Sitting Phantom Using PIMAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akkurt, Hatice; Eckerman, Keith F

2007-01-01

To assess the radiation dose in different configurations when needed (e.g., occupational exposure or public exposure in a radiologically significant event), the mathematical phantom has recently been revised to enable freely moving abilities for arms and legs. The revised phantom is called PIMAL: Phantom with Moving Arms and Legs. Additionally, a graphical user interface has been developed to assist the analyst with input preparation and output manipulation. To investigate the impact of the phantom configuration on the estimated organ doses, PIMAL has been used in a different posture than the standard vertical-upright position. In this paper, the estimated organ andmore » effective dose values for a representative posture, the phantom in a sitting position, compared with those for the phantom in standing position, are presented.« less

Modeling of occupational exposure to accidentally released manufactured nanomaterials in a production facility and calculation of internal doses by inhalation

PubMed Central

Vaquero-Moralejo, Celina; Jaén, María; Lopez De Ipiña Peña, Jesús; Neofytou, Panagiotis

2016-01-01

Background Occupational exposure to manufactured nanomaterials (MNMs) and its potential health impacts are of scientific and practical interest, as previous epidemiological studies associate exposure to nanoparticles with health effects, including increased morbidity of the respiratory and the circulatory system. Objectives To estimate the occupational exposure and effective internal doses in a real production facility of TiO2 MNMs during hypothetical scenarios of accidental release. Methods Commercial software for geometry and mesh generation, as well as fluid flow and particle dispersion calculation, were used to estimate occupational exposure to MNMs. The results were introduced to in-house software to calculate internal doses in the human respiratory tract by inhalation. Results Depending on the accidental scenario, different areas of the production facility were affected by the released MNMs, with a higher dose exposure among individuals closer to the particles source. Conclusions Granted that the study of the accidental release of particles can only be performed by chance, this numerical approach provides valuable information regarding occupational exposure and contributes to better protection of personnel. The methodology can be used to identify occupational settings where the exposure to MNMs would be high during accidents, providing insight to health and safety officials. PMID:27670588

Medical and occupational dose reduction in pediatric barium meal procedures

NASA Astrophysics Data System (ADS)

Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Ledesma, J. A.; Legnani, A.; Bunick, A. P.; Sauzen, J.; Yagui, A.; Vosiak, P.

2017-11-01

Doses received in pediatric Barium Meal procedure can be rather high. It is possible to reduce dose values following the recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP). In the present work, the modifications of radiographic techniques made in a Brazilian hospital according to the EC and the ICRP recommendations and their influence on medical and occupational exposure are reported. The procedures of 49 patients before and 44 after the optimization were studied and air kerma-area product (PK,A) values and the effective doses were evaluated. The occupational equivalent doses were measured next to the eyes, under the thyroid shield and on each hand of both professionals who remained inside the examination room. The implemented modifications reduced by 70% and 60% the PK,A and the patient effective dose, respectively. The obtained dose values are lower than approximately 75% of the results from similar studies. The occupational annual equivalent doses for all studied organs became lower than the limits set by the ICRP. The equivalent doses in one examination were on average below than 75% of similar studies.

Occupational doses and ALARA - recent developments in Sweden

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godas, T.; Viktorsson, C.

1995-03-01

Sweden has traditionally experienced very slow doses to workers in the nuclear industry. However, this trend has since last year been broken mainly due to significant maintenance and repair work. This paper will describe occupational dose trends in Sweden and discuss actions that are being implemented to control this new situation.

Estimation of staff lens doses during interventional procedures. Comparing cardiology, neuroradiology and interventional radiology.

PubMed

Vano, E; Sanchez, R M; Fernandez, J M

2015-07-01

The purpose of this article is to estimate lens doses using over apron active personal dosemeters in interventional catheterisation laboratories (cardiology IC, neuroradiology IN and radiology IR) and to investigate correlations between occupational lens doses and patient doses. Active electronic personal dosemeters placed over the lead apron were used on a sample of 204 IC procedures, 274 IN and 220 IR (all performed at the same university hospital). Patient dose values (kerma area product) were also recorded to evaluate correlations with occupational doses. Operators used the ceiling-suspended screen in most cases. The median and third quartile values of equivalent dose Hp(10) per procedure measured over the apron for IC, IN and IR resulted, respectively, in 21/67, 19/44 and 24/54 µSv. Patient dose values (median/third quartile) were 75/128, 83/176 and 61/159 Gy cm(2), respectively. The median ratios for dosemeters worn over the apron by operators (protected by the ceiling-suspended screen) and patient doses were 0.36; 0.21 and 0.46 µSv Gy(-1) cm(-2), respectively. With the conservative approach used (lens doses estimated from the over apron chest dosemeter) we came to the conclusion that more than 800 procedures y(-1) and per operator were necessary to reach the new lens dose limit for the three interventional specialties. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Combined Use of a Patient Dose Monitoring System and a Real-Time Occupational Dose Monitoring System for Fluoroscopically Guided Interventions.

PubMed

Heilmaier, Christina; Kara, Levent; Zuber, Niklaus; Berthold, Christian; Weishaupt, Dominik

2016-04-01

To determine the effect on patient radiation exposure of the combined use of a patient dose monitoring system and real-time occupational dose monitoring during fluoroscopically guided interventions (FGIs). Patient radiation exposure, in terms of the kerma area product (KAP; Gy ∙ cm(2)), was measured in period 1 with a patient dose monitoring system, and a real-time occupational dose monitoring system was additionally applied in period 2. Mean/median KAP in 19 different types of FGIs was analyzed in both periods for two experienced interventional radiologists combined as well as individually. Patient dose and occupational dose were correlated, applying Pearson and Spearman correlation coefficients. Although FGIs were similar in numbers and types over both periods, a substantial decrease was found for period 2 in total mean ± SD/median KAP for both operators together (period 1, 47 Gy ∙ cm(2) ± 67/41 Gy ∙ cm(2); period 2, 37 Gy ∙ cm(2) ± 69/34 Gy ∙ cm(2)) as well as for each individual operator (for all, P < .05). Overall, KAP declined considerably in 15 of 19 types of FGIs in period 2. Mean accumulated dose per intervention was 4.6 µSv, and mean dose rate was 0.24 mSv/h. There was a strong positive correlation between patient and occupational dose (r = 0.88). Combined use of a patient dose monitoring system and a real-time occupational dose monitoring system in FGIs significantly lessens patient and operator doses. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

10 CFR 835.207 - Occupational dose limits for minors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Occupational dose limits for minors. 835.207 Section 835.207 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External... to radiation and/or radioactive materials at a DOE activity are 0.1 rem (0.001 Sv) total effective...

10 CFR 835.207 - Occupational dose limits for minors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Occupational dose limits for minors. 835.207 Section 835.207 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External... to radiation and/or radioactive materials at a DOE activity are 0.1 rem (0.001 Sv) total effective...

10 CFR 835.207 - Occupational dose limits for minors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Occupational dose limits for minors. 835.207 Section 835.207 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External... to radiation and/or radioactive materials at a DOE activity are 0.1 rem (0.001 Sv) total effective...

10 CFR 835.207 - Occupational dose limits for minors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Occupational dose limits for minors. 835.207 Section 835.207 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External... to radiation and/or radioactive materials at a DOE activity are 0.1 rem (0.001 Sv) total effective...

RADTRAD: A simplified model for RADionuclide Transport and Removal And Dose estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humphreys, S.L.; Miller, L.A.; Monroe, D.K.

1998-04-01

This report documents the RADTRAD computer code developed for the U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Reactor Regulation (NRR) to estimate transport and removal of radionuclides and dose at selected receptors. The document includes a users` guide to the code, a description of the technical basis for the code, the quality assurance and code acceptance testing documentation, and a programmers` guide. The RADTRAD code can be used to estimate the containment release using either the NRC TID-14844 or NUREG-1465 source terms and assumptions, or a user-specified table. In addition, the code can account for a reduction in themore » quantity of radioactive material due to containment sprays, natural deposition, filters, and other natural and engineered safety features. The RADTRAD code uses a combination of tables and/or numerical models of source term reduction phenomena to determine the time-dependent dose at user-specified locations for a given accident scenario. The code system also provides the inventory, decay chain, and dose conversion factor tables needed for the dose calculation. The RADTRAD code can be used to assess occupational radiation exposures, typically in the control room; to estimate site boundary doses; and to estimate dose attenuation due to modification of a facility or accident sequence.« less

Development of cost estimation tools for total occupational safety and health activities and occupational health services: cost estimation from a corporate perspective.

PubMed

Nagata, Tomohisa; Mori, Koji; Aratake, Yutaka; Ide, Hiroshi; Ishida, Hiromi; Nobori, Junichiro; Kojima, Reiko; Odagami, Kiminori; Kato, Anna; Tsutsumi, Akizumi; Matsuda, Shinya

2014-01-01

The aim of the present study was to develop standardized cost estimation tools that provide information to employers about occupational safety and health (OSH) activities for effective and efficient decision making in Japanese companies. We interviewed OSH staff members including full-time professional occupational physicians to list all OSH activities. Using activity-based costing, cost data were obtained from retrospective analyses of occupational safety and health costs over a 1-year period in three manufacturing workplaces and were obtained from retrospective analyses of occupational health services costs in four manufacturing workplaces. We verified the tools additionally in four workplaces including service businesses. We created the OSH and occupational health standardized cost estimation tools. OSH costs consisted of personnel costs, expenses, outsourcing costs and investments for 15 OSH activities. The tools provided accurate, relevant information on OSH activities and occupational health services. The standardized information obtained from our OSH and occupational health cost estimation tools can be used to manage OSH costs, make comparisons of OSH costs between companies and organizations and help occupational health physicians and employers to determine the best course of action.

Effective biological dose from occupational exposure during nanoparticle synthesis

NASA Astrophysics Data System (ADS)

Demou, Evangelia; Tran, Lang; Housiadas, Christos

2009-02-01

Nanomaterial and nanotechnology safety require the characterization of occupational exposure levels for completing a risk assessment. However, equally important is the estimation of the effective internal dose via lung deposition, transport and clearance mechanisms. An integrated source-to-biological dose assessment study is presented using real monitoring data collected during nanoparticle synthesis. Experimental monitoring data of airborne exposure levels during nanoparticle synthesis of CaSO4 and BiPO4 nanoparticles in a research laboratory is coupled with a human lung transport and deposition model, which solves in an Eulerian framework the general dynamic equation for polydisperse aerosols using particle specific physical-chemical properties. Subsequently, the lung deposition model is coupled with a mathematical particle clearance model providing the effective biological dose as well as the time course of the biological dose build-up after exposure. The results for the example of BiPO4 demonstrate that even short exposures throughout the day can lead to particle doses of 1.10·E+08#/(kg-bw·8h-shift), with the majority accumulating in the pulmonary region. Clearance of particles is slow and is not completed within a working shift following a 1 hour exposure. It mostly occurs via macrophage activity in the alveolar region, with small amounts transported to the interstitium and less to the lymph nodes.

Occupational dose constraints in interventional cardiology procedures: the DIMOND approach

NASA Astrophysics Data System (ADS)

Tsapaki, Virginia; Kottou, Sophia; Vano, Eliseo; Komppa, Tuomo; Padovani, Renato; Dowling, Annita; Molfetas, Michael; Neofotistou, Vassiliki

2004-03-01

Radiation fields involved in angiographic suites are most uneven with intensity and gradient varying widely with projection geometry. The European Commission DIMOND III project addressed among others, the issues regarding optimization of staff doses with an attempt to propose preliminary occupational dose constraints. Two thermoluminescent dosemeters (TLD) were used to assess operators' extremity doses (left shoulder and left foot) during 20 coronary angiographies (CAs) and 20 percutaneous transluminal coronary angioplasties (PTCAs) in five European centres. X-ray equipment, radiation protection measures used and the dose delivered to the patient in terms of dose-area product (DAP) were recorded so as to subsequently associate them with operator's dose. The range of staff doses noted for the same TLD position, centre and procedure type emphasizes the importance of protective measures and technical characteristics of x-ray equipment. Correlation of patient's DAP with staff shoulder dose is moderate whereas correlation of patient's DAP with staff foot dose is poor in both CA and PTCA. Therefore, it is difficult to predict operator's dose from patient's DAP mainly due to the different use of protective measures. A preliminary occupational dose constraint value was defined by calculating cardiologists' annual effective dose and found to be 0.6 mSv.

Occupant traffic estimation through structural vibration sensing

NASA Astrophysics Data System (ADS)

Pan, Shijia; Mirshekari, Mostafa; Zhang, Pei; Noh, Hae Young

2016-04-01

The number of people passing through different indoor areas is useful in various smart structure applications, including occupancy-based building energy/space management, marketing research, security, etc. Existing approaches to estimate occupant traffic include vision-, sound-, and radio-based (mobile) sensing methods, which have placement limitations (e.g., requirement of line-of-sight, quiet environment, carrying a device all the time). Such limitations make these direct sensing approaches difficult to deploy and maintain. An indirect approach using geophones to measure floor vibration induced by footsteps can be utilized. However, the main challenge lies in distinguishing multiple simultaneous walkers by developing features that can effectively represent the number of mixed signals and characterize the selected features under different traffic conditions. This paper presents a method to monitor multiple persons. Once the vibration signals are obtained, features are extracted to describe the overlapping vibration signals induced by multiple footsteps, which are used for occupancy traffic estimation. In particular, we focus on analysis of the efficiency and limitations of the four selected key features when used for estimating various traffic conditions. We characterize these features with signals collected from controlled impulse load tests as well as from multiple people walking through a real-world sensing area. In our experiments, the system achieves the mean estimation error of +/-0.2 people for different occupant traffic conditions (from one to four) using k-nearest neighbor classifier.

Estimation of the Dose and Dose Rate Effectiveness Factor

NASA Technical Reports Server (NTRS)

Chappell, L.; Cucinotta, F. A.

2013-01-01

Current models to estimate radiation risk use the Life Span Study (LSS) cohort that received high doses and high dose rates of radiation. Transferring risks from these high dose rates to the low doses and dose rates received by astronauts in space is a source of uncertainty in our risk calculations. The solid cancer models recommended by BEIR VII [1], UNSCEAR [2], and Preston et al [3] is fitted adequately by a linear dose response model, which implies that low doses and dose rates would be estimated the same as high doses and dose rates. However animal and cell experiments imply there should be curvature in the dose response curve for tumor induction. Furthermore animal experiments that directly compare acute to chronic exposures show lower increases in tumor induction than acute exposures. A dose and dose rate effectiveness factor (DDREF) has been estimated and applied to transfer risks from the high doses and dose rates of the LSS cohort to low doses and dose rates such as from missions in space. The BEIR VII committee [1] combined DDREF estimates using the LSS cohort and animal experiments using Bayesian methods for their recommendation for a DDREF value of 1.5 with uncertainty. We reexamined the animal data considered by BEIR VII and included more animal data and human chromosome aberration data to improve the estimate for DDREF. Several experiments chosen by BEIR VII were deemed inappropriate for application to human risk models of solid cancer risk. Animal tumor experiments performed by Ullrich et al [4], Alpen et al [5], and Grahn et al [6] were analyzed to estimate the DDREF. Human chromosome aberration experiments performed on a sample of astronauts within NASA were also available to estimate the DDREF. The LSS cohort results reported by BEIR VII were combined with the new radiobiology results using Bayesian methods.

[Evaluation of Organ Dose Estimation from Indices of CT Dose Using Dose Index Registry].

PubMed

Iriuchijima, Akiko; Fukushima, Yasuhiro; Ogura, Akio

Direct measurement of each patient organ dose from computed tomography (CT) is not possible. Most methods to estimate patient organ dose is using Monte Carlo simulation with dedicated software. However, dedicated software is too expensive for small scale hospitals. Not every hospital can estimate organ dose with dedicated software. The purpose of this study was to evaluate the simple method of organ dose estimation using some common indices of CT dose. The Monte Carlo simulation software Radimetrics (Bayer) was used for calculating organ dose and analysis relationship between indices of CT dose and organ dose. Multidetector CT scanners were compared with those from two manufactures (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare). Using stored patient data from Radimetrics, the relationships between indices of CT dose and organ dose were indicated as each formula for estimating organ dose. The accuracy of estimation method of organ dose was compared with the results of Monte Carlo simulation using the Bland-Altman plots. In the results, SSDE was the feasible index for estimation organ dose in almost organs because it reflected each patient size. The differences of organ dose between estimation and simulation were within 23%. In conclusion, our estimation method of organ dose using indices of CT dose is convenient for clinical with accuracy.

How Valid are Estimates of Occupational Illness?

ERIC Educational Resources Information Center

Hilaski, Harvey J.; Wang, Chao Ling

1982-01-01

Examines some of the methods of estimating occupational diseases and suggests that a consensus on the adequacy and reliability of estimates by the Bureau of Labor Statistics and others is not likely. (SK)

10 CFR 20.1502 - Conditions requiring individual monitoring of external and internal occupational dose.

Code of Federal Regulations, 2014 CFR

2014-01-01

... internal occupational dose. 20.1502 Section 20.1502 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Surveys and Monitoring § 20.1502 Conditions requiring individual monitoring of external and internal occupational dose. Each licensee shall monitor exposures to radiation and radioactive...

10 CFR 20.1502 - Conditions requiring individual monitoring of external and internal occupational dose.

Code of Federal Regulations, 2012 CFR

2012-01-01

... internal occupational dose. 20.1502 Section 20.1502 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Surveys and Monitoring § 20.1502 Conditions requiring individual monitoring of external and internal occupational dose. Each licensee shall monitor exposures to radiation and radioactive...

10 CFR 20.1502 - Conditions requiring individual monitoring of external and internal occupational dose.

Code of Federal Regulations, 2011 CFR

2011-01-01

... internal occupational dose. 20.1502 Section 20.1502 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Surveys and Monitoring § 20.1502 Conditions requiring individual monitoring of external and internal occupational dose. Each licensee shall monitor exposures to radiation and radioactive...

10 CFR 20.1502 - Conditions requiring individual monitoring of external and internal occupational dose.

Code of Federal Regulations, 2013 CFR

2013-01-01

... internal occupational dose. 20.1502 Section 20.1502 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Surveys and Monitoring § 20.1502 Conditions requiring individual monitoring of external and internal occupational dose. Each licensee shall monitor exposures to radiation and radioactive...

10 CFR 20.1502 - Conditions requiring individual monitoring of external and internal occupational dose.

Code of Federal Regulations, 2010 CFR

2010-01-01

... internal occupational dose. 20.1502 Section 20.1502 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Surveys and Monitoring § 20.1502 Conditions requiring individual monitoring of external and internal occupational dose. Each licensee shall monitor exposures to radiation and radioactive...

Radiation Dose Reconstruction Program of the National Institute for Occupational Safety and Health: overview.

PubMed

Neton, James W; Howard, John; Elliott, Larry J

2008-07-01

Over the past 65 years, hundreds of thousands of workers have been engaged in nuclear weapons-related activities for the U.S. Department of Energy or its predecessor agencies. To date, almost 27,000 such employees (or their survivors) have filed claims under Part B of the Energy Employees Occupational Illness Compensation Program Act of 2000, which provides monetary compensation and medical benefits to energy employees who have developed certain types of cancer that have been determined, under the guidelines of the program, to have resulted from occupational radiation exposure covered under the Act. Although it is difficult to predict the number of cancer claims that will be evaluated under this program, the number could double or triple. In each case, the processing of a claim requires that the National Institute for Occupational Safety and Health reconstruct the radiation dose received by the employee followed by a determination by the U.S. Department of Labor as to whether the employee was "at least as likely as not" to have sustained the cancer as a result of his or her occupational exposure to ionizing radiation. Although some of the dose assessments are straightforward, many are extremely complex due to (1) missing, non-interpretable, or undocumented records; (2) a wide variety of external and internal exposure conditions; and/or (3) highly variable work assignments and work loads. The program objectives are to process claims in an effective, efficient, and timely manner. One of the initial challenges was to develop the necessary infrastructure to meet these objectives. Subsequent challenges included documenting that assessments are fair and scientifically consistent. Ensuring that each claimant receives the "benefit of the doubt" in any cases where the required background information and data are ambiguous or not available is also an important objective. Fortunately, there are some aspects of the processing requirements that have tended to reduce the

The estimation of occupational dose in 15 MV varian clinac iX room by Argon-41 as an activation product of photoneutron

NASA Astrophysics Data System (ADS)

Latifah, R.; Bunawas; Noor, J. A. E.

2018-03-01

Linear accelerator (linac) becomes the most commonly used treatment to damage and kill cancer cell. Photon and electron as the radiation beam are produced by accelerating electrons to very high energy. Neutrons are generated when incident high photon energy interacts with component of linac such as target, flattering filter and collimator via photoneutrons reaction. The neutrons can also produce activation of materials in treatment room to generate radioactive materials. We have estimated the concentration of Argon-41 as activated product from argon-40 in the linac room using foil activation. The results show that the Argon-41 concentration in linac room which is operated 15 MV for 1 treatment (1 minute) is 1440 Bq/m3. Accordingly that concentration, the occupational dose is 6.4 mSv per year.

Estimating occupational exposure to carcinogens in Quebec.

PubMed

Labrèche, France; Duguay, Patrice; Ostiguy, Claude; Boucher, Alexandre; Roberge, Brigitte; Peters, Cheryl E; Demers, Paul A

2013-09-01

We estimated the extent of exposure to occupational carcinogens in Quebec, Canada, to help raise awareness of occupational cancers. Proportions of workers exposed to 21 recognized and 17 probable carcinogens (according to Quebec occupational health regulation and the International Agency for Research on Cancer [IARC] classification) were extracted from various sources: workplace monitoring data, research projects, a population survey, radiation protection data, exposure estimates from the Carcinogen Exposure Canada (CAREX Canada) Project database, and published exposure data. These proportions were applied to Quebec labor force data. Among the 38 studied, carcinogens with the largest proportions of exposed workers were solar radiation (6.6% of workers), night shift work/rotating shift work including nights (6.0%), diesel exhaust fumes (4.4%), wood dust (2.9%) and polycyclic aromatic hydrocarbons (2.0%). More than 15 carcinogens were identified in several industrial sectors, and up to 100,000 young workers are employed in these sectors. Although crude, estimates obtained with different data sources allow identification of research and intervention priorities for cancer in Quebec. Copyright © 2013 Wiley Periodicals, Inc.

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2010 CFR

2010-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2010-01-01 2010-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2014 CFR

2014-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2014-01-01 2014-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2012 CFR

2012-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2012-01-01 2012-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2013 CFR

2013-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2013-01-01 2013-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2011 CFR

2011-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2011-01-01 2011-01-01 false Occupational dose limits for general employees. 835.202...

OCCUPATIONAL DOSE DURING ADULT INTERVENTIONAL CARDIOLOGY: FIRST VALUES WITH PERSONAL ACTIVE DOSIMETERS IN CHILE.

PubMed

Ubeda, Carlos; Morales, Claudio; Gutiérrez, Diego; Oliveira, Marcus; Manterola, Carlos

2018-05-11

The objective of this article is to present initial occupational dose values using digital active personal dosimeters for medical staff during adult interventional cardiology procedures in a public hospital in Chile. Personal dose equivalent Hp(10) over the lead apron of physician, nurse and radiographer were measured during 59 procedures. Mean values of occupational dose Hp(10) per procedure were 47.6, 6.2 and 4.3 μSv for physician, nurse and radiographer, respectively. If no protective tools are used, physician dose can exceed the new eye lens dose limit.

Estimation of median human lethal radiation dose computed from data on occupants of reinforced concrete structures in Nagasaki, Japan.

PubMed

Levin, S G; Young, R W; Stohler, R L

1992-11-01

This paper presents an estimate of the median lethal dose for humans exposed to total-body irradiation and not subsequently treated for radiation sickness. The median lethal dose was estimated from calculated doses to young adults who were inside two reinforced concrete buildings that remained standing in Nagasaki after the atomic detonation. The individuals in this study, none of whom have previously had calculated doses, were identified from a detailed survey done previously. Radiation dose to the bone marrow, which was taken as the critical radiation site, was calculated for each individual by the Engineering Physics and Mathematics Division of the Oak Ridge National Laboratory using a new three-dimensional discrete-ordinates radiation transport code that was developed and validated for this study using the latest site geometry, radiation yield, and spectra data. The study cohort consisted of 75 individuals who either survived > 60 d or died between the second and 60th d postirradiation due to radiation injury, without burns or other serious injury. Median lethal dose estimates were calculated using both logarithmic (2.9 Gy) and linear (3.4 Gy) dose scales. Both calculations, which met statistical validity tests, support previous estimates of the median lethal dose based solely on human data, which cluster around 3 Gy.

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

PubMed

Omar, Artur; Kadesjö, Nils; Palmgren, Charlotta; Marteinsdottir, Maria; Segerdahl, Tony; Fransson, Annette

2017-03-20

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.

A U.S. Multicenter Study of Recorded Occupational Radiation Badge Doses in Nuclear Medicine.

PubMed

Villoing, Daphnée; Yoder, R Craig; Passmore, Christopher; Bernier, Marie-Odile; Kitahara, Cari M

2018-05-01

Purpose To summarize occupational badge doses recorded for a sample of U.S. nuclear medicine technologists. Materials and Methods Nine large U.S. medical institutions identified 208 former and current nuclear medicine technologists certified after 1979 and linked these individuals to historic badge dose records maintained by a commercial dosimetry company (Landauer), yielding a total of 2618 annual dose records. The distributions of annual and cumulative occupational doses were described by using summary statistics. Results Between 1992 and 2015, the median annual personal dose equivalent per nuclear medicine technologist was 2.18 mSv (interquartile range [IQR], 1.25-3.47 mSv; mean, 2.69 mSv). Median annual personal dose equivalents remained relatively constant over this period (range, 1.40-3.30 mSv), while maximum values generally increased over time (from 8.00 mSv in 1992 to 13.9 mSv in 2015). The median cumulative personal dose equivalent was 32.9 mSv (IQR, 18.1-65.5 mSv; mean, 51.4 mSv) for 45 technologists who had complete information and remained employed through 2015. Conclusion Occupational radiation doses were well below the established occupational limits and were consistent with those observed for nuclear medicine technologists worldwide and were greater than those observed for nuclear and general medical workers in the United States These results should be informative for radiation monitoring and safety efforts in nuclear medicine departments. © RSNA, 2018 Online supplemental material is available for this article.

Radiation dose to technologists per nuclear medicine examination and estimation of annual dose.

PubMed

Bayram, Tuncay; Yilmaz, A Hakan; Demir, Mustafa; Sonmez, Bircan

2011-03-01

Conventional diagnostic nuclear medicine applications have been continuously increasing in most nuclear medicine departments in Turkey, but to our knowledge no one has studied the doses to technologists who perform nuclear medicine procedures. Most nuclear medicine laboratories do not have separate control rooms for technologists, who are quite close to the patient during data acquisition. Technologists must therefore stay behind lead shields while performing their task if they are to reduce the radiation dose received. The aim of this study was to determine external radiation doses to technologists during nuclear medicine procedures with and without a lead shield. Another aim was to investigate the occupational annual external radiation doses to Turkish technologists. This study used a Geiger-Müller detector to measure dose rates to technologists at various distances from patients (0.25, 0.50, 1, and 2 m and behind a lead shield) and determined the average time spent by technologists at these distances. Deep-dose equivalents to technologists were obtained. The following conventional nuclear medicine procedures were considered: thyroid scintigraphy performed using (99m)Tc pertechnetate, whole-body bone scanning performed using (99m)Tc-methylene diphosphonate, myocardial perfusion scanning performed using (99m)Tc-methoxyisobutyl isonitrile, and (201)Tl (thallous chloride) and renal scanning performed using (99m)Tc-dimercaptosuccinic acid. The measured deep-dose equivalent to technologists per procedure was within the range of 0.13 ± 0.05 to 0.43 ± 0.17 μSv using a lead shield and 0.21 ± 0.07 to 1.01 ± 0.46 μSv without a lead shield. Also, the annual individual dose to a technologist performing only a particular scintigraphic procedure throughout a year was estimated. For a total of 95 clinical cases (71 patients), effective external radiation doses to technologists were found to be within the permissible levels. This study showed that a 2-mm lead shield

MO-F-CAMPUS-I-02: Occupational Conceptus Doses From Fluoroscopically-Guided Interventional Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Damilakis, J; Perisinakis, K; Solomou, G

Purpose: The aim of this method was to provide dosimetric data on conceptus dose for the pregnant employee who participates in fluoroscopically-guided interventional procedures. Methods: Scattered air-kerma dose rates were obtained for 17 fluoroscopic projections involved in interventional procedures. These projections were simulated on an anthropomorphic phantom placed on the examination table supine. The operating theater was divided into two grids relative to the long table sides. Each grid consisted of 33 cells spaced 0.50 m apart. During the simulated exposures, at each cell, scatter air-kerma rate was measured at 110 cm from the floor i.e. at the height ofmore » the waist of the pregnant worker. Air-kerma rates were divided by the dose area product (DAP) rate of each exposure to obtain normalized data. For each projection, measurements were performed for 3 kVp and 3 filtration values i.e. for 9 different x-ray spectra. All measurements were performed by using a modern C-arm angiographic system (Siemens Axiom Artis, Siemens, Germany) and a radiation meter equipped with an ionization chamber. Results: The results consist of 153 iso-dose maps, which show the spatial distribution of DAP-normalized scattered air-kerma doses at the waist level of a pregnant worker. Conceptus dose estimation is possible using air-kerma to embryo/fetal dose conversion coefficients published in a previous study (J Cardiovasc Electrophysiol, Vol. 16, pp. 1–8, July 2005). Using these maps, occupationally exposed pregnant personnel may select a working position for a certain projection that keeps abdominal dose as low as reasonably achievable. Taking into consideration the regulatory conceptus dose limit for occupational exposure, determination of the maximum workload allowed for the pregnant personnel is also possible. Conclusion: Data produced in this work allow for the anticipation of conceptus dose and the determination of the maximum workload for a pregnant worker from any

Using physiologically based pharmacokinetic modeling and benchmark dose methods to derive an occupational exposure limit for N-methylpyrrolidone.

PubMed

Poet, T S; Schlosser, P M; Rodriguez, C E; Parod, R J; Rodwell, D E; Kirman, C R

2016-04-01

The developmental effects of NMP are well studied in Sprague-Dawley rats following oral, inhalation, and dermal routes of exposure. Short-term and chronic occupational exposure limit (OEL) values were derived using an updated physiologically based pharmacokinetic (PBPK) model for NMP, along with benchmark dose modeling. Two suitable developmental endpoints were evaluated for human health risk assessment: (1) for acute exposures, the increased incidence of skeletal malformations, an effect noted only at oral doses that were toxic to the dam and fetus; and (2) for repeated exposures to NMP, changes in fetal/pup body weight. Where possible, data from multiple studies were pooled to increase the predictive power of the dose-response data sets. For the purposes of internal dose estimation, the window of susceptibility was estimated for each endpoint, and was used in the dose-response modeling. A point of departure value of 390 mg/L (in terms of peak NMP in blood) was calculated for skeletal malformations based on pooled data from oral and inhalation studies. Acceptable dose-response model fits were not obtained using the pooled data for fetal/pup body weight changes. These data sets were also assessed individually, from which the geometric mean value obtained from the inhalation studies (470 mg*hr/L), was used to derive the chronic OEL. A PBPK model for NMP in humans was used to calculate human equivalent concentrations corresponding to the internal dose point of departure values. Application of a net uncertainty factor of 20-21, which incorporates data-derived extrapolation factors, to the point of departure values yields short-term and chronic occupational exposure limit values of 86 and 24 ppm, respectively. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Dose-response relations between occupational exposures to physical and psychosocial factors and the risk of low back pain

PubMed Central

Jansen, J; Morgenstern, H; Burdorf, A

2004-01-01

Aims: To assess dose-response relations between occupational exposures to physical and psychosocial factors and the risk of low back pain. Methods: A cohort of 523 subjects, working in nursing homes and homes for the elderly, was followed prospectively for one year. Physical load for different occupations was assessed by quantitative observations at the workplace. Information on low back pain and other factors was gathered with questionnaires administered at baseline and at one year. Two outcome measures of low back pain incidence were used: any new episode of pain lasting for at least a few hours during follow up (LBP); and any new episode of disabling pain that interfered with daily activities during follow up (LBP/D). Hierarchical regression analysis with a spline function was used to estimate dose-response relations. Results: The risk of LBP was not associated with physical factors, controlling for confounders; but this outcome was inversely associated with age and weakly, though imprecisely, associated with two psychosocial factors—low decision authority and high work demands. In contrast, the risk of LBP/D was positively associated with age and not associated with the psychosocial factors. Trunk flexion over 45 degrees was monotonically associated with the risk of LBP/D; the estimated relative risk was 3.18 (95% CI 1.13 to 9.00) for 1 hour and 45 minutes of bending per week (90th centile), relative to 30 minutes per week. The hierarchical estimates of effect were more stable than were the maximum likelihood estimates. Conclusion: Occupational exposure to trunk flexion over 45 degrees appears to be a risk factor for low back pain with disability among persons employed in nursing homes and homes for the elderly in the Netherlands. PMID:15550602

Dose received by occupationally exposed workers at a nuclear medicine department

NASA Astrophysics Data System (ADS)

Ávila, O.; Sánchez-Uribe, N. A.; Rodríguez-Laguna, A.; Medina, L. A.; Estrada, E.; Buenfil, A. E.; Brandan, M. E.

2012-10-01

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

Dose received by occupationally exposed workers at a nuclear medicine department

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avila, O.; Sanchez-Uribe, N. A.; Rodriguez-Laguna, A.

2012-10-23

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

10 CFR 20.2104 - Determination of prior occupational dose.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 20.2104 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Records § 20... occupational radiation dose received during the current year. (b) Prior to permitting an individual to... statement from the individual, or from the individual's most recent employer for work involving radiation...

10 CFR 20.2104 - Determination of prior occupational dose.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 20.2104 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Records § 20... occupational radiation dose received during the current year. (b) Prior to permitting an individual to... statement from the individual, or from the individual's most recent employer for work involving radiation...

10 CFR 20.2104 - Determination of prior occupational dose.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 20.2104 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Records § 20... occupational radiation dose received during the current year. (b) Prior to permitting an individual to... statement from the individual, or from the individual's most recent employer for work involving radiation...

10 CFR 20.2104 - Determination of prior occupational dose.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 20.2104 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Records § 20... occupational radiation dose received during the current year. (b) Prior to permitting an individual to... statement from the individual, or from the individual's most recent employer for work involving radiation...

10 CFR 20.2104 - Determination of prior occupational dose.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 20.2104 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Records § 20... occupational radiation dose received during the current year. (b) Prior to permitting an individual to... statement from the individual, or from the individual's most recent employer for work involving radiation...

Multi-scale occupancy estimation and modelling using multiple detection methods

USGS Publications Warehouse

Nichols, James D.; Bailey, Larissa L.; O'Connell, Allan F.; Talancy, Neil W.; Grant, Evan H. Campbell; Gilbert, Andrew T.; Annand, Elizabeth M.; Husband, Thomas P.; Hines, James E.

2008-01-01

Occupancy estimation and modelling based on detection–nondetection data provide an effective way of exploring change in a species’ distribution across time and space in cases where the species is not always detected with certainty. Today, many monitoring programmes target multiple species, or life stages within a species, requiring the use of multiple detection methods. When multiple methods or devices are used at the same sample sites, animals can be detected by more than one method.We develop occupancy models for multiple detection methods that permit simultaneous use of data from all methods for inference about method-specific detection probabilities. Moreover, the approach permits estimation of occupancy at two spatial scales: the larger scale corresponds to species’ use of a sample unit, whereas the smaller scale corresponds to presence of the species at the local sample station or site.We apply the models to data collected on two different vertebrate species: striped skunks Mephitis mephitis and red salamanders Pseudotriton ruber. For striped skunks, large-scale occupancy estimates were consistent between two sampling seasons. Small-scale occupancy probabilities were slightly lower in the late winter/spring when skunks tend to conserve energy, and movements are limited to males in search of females for breeding. There was strong evidence of method-specific detection probabilities for skunks. As anticipated, large- and small-scale occupancy areas completely overlapped for red salamanders. The analyses provided weak evidence of method-specific detection probabilities for this species.Synthesis and applications. Increasingly, many studies are utilizing multiple detection methods at sampling locations. The modelling approach presented here makes efficient use of detections from multiple methods to estimate occupancy probabilities at two spatial scales and to compare detection probabilities associated with different detection methods. The models can be

[Estimates of Attributable Fraction of occupational cancers in the recent epidemiological literature].

PubMed

Merler, Enzo

2009-01-01

The article reviews the estimates of Attributable Fraction (AF) of occupational cancers. Because of their relevance, it starts with a synthesis and a comment on the estimates of avoidable cancers, and among these of cancers due to occupation, as expressed in 1981 by Doll and Peto. The main studies that have brought back into the epidemiological pathway the exercise of producing FA are quoted and the results of the new studies reviewed. The dimension of occupational cancers is of public health importance, because caused by exposures assumed to be avoidable. However, the estimates of AF are prone to uncertainties and limitations. Occupational cancers represent the major killer among deaths due to occupational diseases and injuries and a relevant fraction, especially among males, of total cancers. When related to developed countries, estimates may underestimate the risks, because of the insufficient data on exposures for workers in small firms, the lack of information on exposures in agriculture, the scanty availability of epidemiological studies on cancer risks among women. The trend towards a reduction of employees in industrial activities, the elimination or control of some exposures should suggest, instead, a reduction for occupational cancer. However, the more recent estimates of AF of occupational cancers are still in line with the estimates expressed more that 20 years ago. In developing countries, the estimates of AF are plenty of assumptions. In addition, some characteristics (i.e. the younger age of starting work, the extension of work at older age) suggest the need of better data, whereas information on exposures and events are dramatically lacking.

Fuzzy approach for reducing subjectivity in estimating occupational accident severity.

PubMed

Pinto, Abel; Ribeiro, Rita A; Nunes, Isabel L

2012-03-01

Quantifying or, more generally, estimating the severity of the possible consequences of occupational accidents is a decisive step in any occupational risk assessment process. Because of the lack of historic information (accident data collection and recording are incipient and insufficient, particularly in construction) and the lack of practical tools in the construction industry, the estimation/quantification of occupational accident severity is a notably arbitrary process rather than a systematic and rigorous assessment. This work proposes several severity functions (based on a safety risk assessment) to represent biomechanical knowledge with the aim of determining the severity level of occupational accidents in the construction industry and, consequently, improving occupational risk assessment quality. We follow a fuzzy approach because it makes it possible to capture and represent imprecise knowledge in a simple and understandable way for users and specialists. Copyright © 2011 Elsevier Ltd. All rights reserved.

Estimating site occupancy rates when detection probabilities are less than one

USGS Publications Warehouse

MacKenzie, D.I.; Nichols, J.D.; Lachman, G.B.; Droege, S.; Royle, J. Andrew; Langtimm, C.A.

2002-01-01

Nondetection of a species at a site does not imply that the species is absent unless the probability of detection is 1. We propose a model and likelihood-based method for estimating site occupancy rates when detection probabilities are 0.3). We estimated site occupancy rates for two anuran species at 32 wetland sites in Maryland, USA, from data collected during 2000 as part of an amphibian monitoring program, Frogwatch USA. Site occupancy rates were estimated as 0.49 for American toads (Bufo americanus), a 44% increase over the proportion of sites at which they were actually observed, and as 0.85 for spring peepers (Pseudacris crucifer), slightly above the observed proportion of 0.83.

Evaluation of scattered radiation emitted from X-ray security scanners on occupational dose to airport personnel

NASA Astrophysics Data System (ADS)

Dalah, Entesar; Fakhry, Angham; Mukhtar, Asma; Al Salti, Farah; Bader, May; Khouri, Sara; Al-Zahmi, Reem

2017-06-01

Based on security issues and regulations airports are provided with luggage cargo scanners. These scanners utilize ionizing radiation that in principle present health risks toward humans. The study aims to investigate the amount of backscatter produced by passenger luggage and cargo toward airport personnel who are located at different distances from the scanners. To approach our investigation a Thermo Electron Radeye-G probe was used to quantify the backscattered radiation measured in terms of dose-rate emitted from airport scanners, Measurements were taken at the entrance and exit positions of the X-ray tunnel at three different distances (0, 50, and 100 cm) for two different scanners; both scanners include shielding curtains that reduce scattered radiation. Correlation was demonstrated using the Pearson coefficient test. Measurements confirmed an inverse relationship between dose rate and distance. An estimated occupational accumulative dose of 0.88 mSv/y, and 2.04 mSv/y were obtained for personnel working in inspection of carry-on, and cargo, respectively. Findings confirm that the projected dose of security and engineering staff are being well within dose limits.

Higher serotonin transporter occupancy after multiple dose administration of escitalopram compared to citalopram: an [123I]ADAM SPECT study.

PubMed

Klein, Nikolas; Sacher, Julia; Geiss-Granadia, Thomas; Mossaheb, Nilufar; Attarbaschi, Trawat; Lanzenberger, Rupert; Spindelegger, Christoph; Holik, Alexander; Asenbaum, Susanne; Dudczak, Robert; Tauscher, Johannes; Kasper, Siegfried

2007-04-01

Previous studies have investigated the occupancy of the serotonin reuptake transporter (SERT) after clinical doses of citalopram and other selective serotonin reuptake inhibitors. In the present study, the occupancies of SERT after multiple doses of escitalopram and citalopram were compared using the radioligand [(123)I]ADAM and single photon emission computed tomography (SPECT). Fifteen healthy subjects received escitalopram 10 mg/day (n = 6) or citalopram 20 mg/day (n = 9) for a total of 10 days. SERT occupancies in midbrain were determined with SPECT and [(123)I]ADAM at three different time points: at baseline (no medication) and at 6 and 54 h after last drug intake. At 6 h after the last dose, mean SERT occupancies were 81.5 +/- 5.4% (mean+/-SD) for escitalopram and 64.0 +/- 12.7% for citalopram (p < 0.01). At 54 h after the last dose, mean SERT occupancies were 63.3 +/- 12.1% for escitalopram and 49.0 +/- 11.7% for citalopram (p < 0.05). The plasma concentrations of the S-enantiomer were of the same magnitude in both substances. For both drugs, the elimination rate of the S-enantiomer in plasma was markedly higher than the occupancy decline rate in the midbrain. The significantly higher occupancy of SERT after multiple doses of escitalopram compared to citalopram indicates an increased inhibition of SERT by escitalopram. The results can also be explained by an attenuating effect of R-citalopram on the occupancy of S-citalopram at the SERT.

Estimation of background radiation doses for the Peninsular Malaysia's population by ESR dosimetry of tooth enamel.

PubMed

Rodzi, Mohd; Zhumadilov, Kassym; Ohtaki, Megu; Ivannikov, Alexander; Bhattacharjee, Deborshi; Fukumura, Akifumi; Hoshi, Masaharu

2011-08-01

Background radiation dose is used in dosimetry for estimating occupational doses of radiation workers or determining radiation dose of an individual following accidental exposure. In the present study, the absorbed dose and the background radiation level are determined using the electron spin resonance (ESR) method on tooth samples. The effect of using different tooth surfaces and teeth exposed with single medical X-rays on the absorbed dose are also evaluated. A total of 48 molars of position 6-8 were collected from 13 district hospitals in Peninsular Malaysia. Thirty-six teeth had not been exposed to any excessive radiation, and 12 teeth had been directly exposed to a single X-ray dose during medical treatment prior to extraction. There was no significant effect of tooth surfaces and exposure with single X-rays on the measured absorbed dose of an individual. The mean measured absorbed dose of the population is 34 ± 6.2 mGy, with an average tooth enamel age of 39 years. From the slope of a regression line, the estimated annual background dose for Peninsular Malaysia is 0.6 ± 0.3 mGy y(-1). This value is slightly lower than the yearly background dose for Malaysia, and the radiation background dose is established by ESR tooth measurements on samples from India and Russia.

Hierarchical Bayes estimation of species richness and occupancy in spatially replicated surveys

USGS Publications Warehouse

Kery, M.; Royle, J. Andrew

2008-01-01

1. Species richness is the most widely used biodiversity metric, but cannot be observed directly as, typically, some species are overlooked. Imperfect detectability must therefore be accounted for to obtain unbiased species-richness estimates. When richness is assessed at multiple sites, two approaches can be used to estimate species richness: either estimating for each site separately, or pooling all samples. The first approach produces imprecise estimates, while the second loses site-specific information. 2. In contrast, a hierarchical Bayes (HB) multispecies site-occupancy model benefits from the combination of information across sites without losing site-specific information and also yields occupancy estimates for each species. The heart of the model is an estimate of the incompletely observed presence-absence matrix, a centrepiece of biogeography and monitoring studies. We illustrate the model using Swiss breeding bird survey data, and compare its estimates with the widely used jackknife species-richness estimator and raw species counts. 3. Two independent observers each conducted three surveys in 26 1-km(2) quadrats, and detected 27-56 (total 103) species. The average estimated proportion of species detected after three surveys was 0.87 under the HB model. Jackknife estimates were less precise (less repeatable between observers) than raw counts, but HB estimates were as repeatable as raw counts. The combination of information in the HB model thus resulted in species-richness estimates presumably at least as unbiased as previous approaches that correct for detectability, but without costs in precision relative to uncorrected, biased species counts. 4. Total species richness in the entire region sampled was estimated at 113.1 (CI 106-123); species detectability ranged from 0.08 to 0.99, illustrating very heterogeneous species detectability; and species occupancy was 0.06-0.96. Even after six surveys, absolute bias in observed occupancy was estimated at up to 0

Does the Level of Occupational Aggregation Affect Estimates of the Gender Wage Gap?

ERIC Educational Resources Information Center

Kidd, Michael P.; Shannon, Michael

1996-01-01

Using data from the 1989 Canadian Labour-Market Activity Survey, when occupation is treated as a productivity-related characteristic, gender wage gap estimates are distorted. Using a larger number of occupations, the occupational aggregation by gender reflects barriers women face in attempting to enter male-dominated occupations. (SK)

Estimating site occupancy and abundance using indirect detection indices

USGS Publications Warehouse

Stanley, T.R.; Royle, J. Andrew

2005-01-01

Knowledge of factors influencing animal distribution and abundance is essential in many areas of ecological research, management, and policy-making. Because common methods for modeling and estimating abundance (e.g., capture-recapture, distance sampling) are sometimes not practical for large areas or elusive species, indices are sometimes used as surrogate measures of abundance. We present an extension of the Royle and Nichols (2003) generalization of the MacKenzie et al. (2002) site-occupancy model that incorporates length of the sampling interval into the, model for detection probability. As a result, we obtain a modeling framework that shows how useful information can be extracted from a class of index methods we call indirect detection indices (IDIs). Examples of IDIs include scent station, tracking tube, snow track, tracking plate, and hair snare surveys. Our model is maximum likelihood, and it can be used to estimate site occupancy and model factors influencing patterns of occupancy and abundance in space. Under certain circumstances, it can also be used to estimate abundance. We evaluated model properties using Monte Carlo simulations and illustrate the method with tracking tube and scent station data. We believe this model will be a useful tool for determining factors that influence animal distribution and abundance.

Evaluating health risks from occupational exposure to pesticides and the regulatory response.

PubMed Central

Woodruff, T J; Kyle, A D; Bois, F Y

1994-01-01

In this study, we used measurements of occupational exposures to pesticides in agriculture to evaluate health risks and analyzed how the federal regulatory program is addressing these risks. Dose estimates developed by the State of California from measured occupational exposures to 41 pesticides were compared to standard indices of acute toxicity (LD50) and chronic effects (reference dose). Lifetime cancer risks were estimated using cancer potencies. Estimated absorbed daily doses for mixers, loaders, and applicators of pesticides ranged from less than 0.0001% to 48% of the estimated human LD50 values, and doses for 10 of 40 pesticides exceeded 1% of the estimated human LD50 values. Estimated lifetime absorbed daily doses ranged from 0.1% to 114,000% of the reference doses developed by the U.S. Environmental Protection Agency, and doses for 13 of 25 pesticides were above them. Lifetime cancer risks ranged from 1 per million to 1700 per million, and estimates for 12 of 13 pesticides were above 1 per million. Similar results were obtained for field workers and flaggers. For the pesticides examined, exposures pose greater risks of chronic effects than acute effects. Exposure reduction measures, including use of closed mixing systems and personal protective equipment, significantly reduced exposures. Proposed regulations rely primarily on requirements for personal protective equipment and use restrictions to protect workers. Chronic health risks are not considered in setting these requirements. Reviews of pesticides by the federal pesticide regulatory program have had little effect on occupational risks. Policy strategies that offer immediate protection for workers and that are not dependent on extensive review of individual pesticides should be pursued. Images Figure 1. PMID:7713022

Quantitative PET Imaging in Drug Development: Estimation of Target Occupancy.

PubMed

Naganawa, Mika; Gallezot, Jean-Dominique; Rossano, Samantha; Carson, Richard E

2017-12-11

Positron emission tomography, an imaging tool using radiolabeled tracers in humans and preclinical species, has been widely used in recent years in drug development, particularly in the central nervous system. One important goal of PET in drug development is assessing the occupancy of various molecular targets (e.g., receptors, transporters, enzymes) by exogenous drugs. The current linear mathematical approaches used to determine occupancy using PET imaging experiments are presented. These algorithms use results from multiple regions with different target content in two scans, a baseline (pre-drug) scan and a post-drug scan. New mathematical estimation approaches to determine target occupancy, using maximum likelihood, are presented. A major challenge in these methods is the proper definition of the covariance matrix of the regional binding measures, accounting for different variance of the individual regional measures and their nonzero covariance, factors that have been ignored by conventional methods. The novel methods are compared to standard methods using simulation and real human occupancy data. The simulation data showed the expected reduction in variance and bias using the proper maximum likelihood methods, when the assumptions of the estimation method matched those in simulation. Between-method differences for data from human occupancy studies were less obvious, in part due to small dataset sizes. These maximum likelihood methods form the basis for development of improved PET covariance models, in order to minimize bias and variance in PET occupancy studies.

[Dosimetric system for assessing doses received by people occupationally exposed to external sources of ionizing radiation].

PubMed

Brodecki, Marcin; Domienik, Joanna U; Zmyślony, Marek

2012-01-01

The current system of dosimetric quantities has been defined by the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU). Complexity of the system implies the physical nature of ionizing radiation, resulting from the presence of different types of radiation of different ionization capabilities, as well as the individual radiation sensitivity of biological material exposed. According to the latest recommendations, there are three types of dosimeter quantities relevant to radiation protection and radiological assessment of occupational exposure. These are the basic quantities, safety quantities and operational quantities. Dose limits for occupational exposure relate directly to the protection quantities, i.e. the equivalent dose and effective dose, while these quantities are practically unmeasurable in real measurement conditions. For this reason, in the system of dosimetric quantities directly measurable operating volumes were defined. They represent equivalents of the protection quantities that allow for a reliable assessment of equivalent and effective dose by conducting routine monitoring of occupational exposure. This paper presents the characteristics of these quantities, their relationships and importance in assessing individual effects of radiation. Also the methods for their implementation in personal and environmental dosimetry were showcased. The material contained in the article is a compendium of essential information about dosimetric quantities with reference to the contemporary requirements of the law, including the changed annual occupational exposure limit for the lens of the eye. The material is especially addressed to those responsible for dosimetry monitoring in the workplace, radiation protection inspectors and occupational health physicians.

Survey on low-dose medical radiation exposure in occupational workers: the effect on hematological change

NASA Astrophysics Data System (ADS)

Ryu, J. K.; Cho, S. M.; Cho, J. H.; Dong, K. R.; Chung, W. K.; Lee, J. W.

2013-03-01

This study examined the changes in the hematological index caused by low-dose medical radiation exposure in workers in a medical radiation-exposed environment. The cumulative dose was obtained using thermoluminescent dosimeters over a 9-year period, and the changes in hematological index count (red blood cells (RBCs), hemoglobin, platelets, white blood cells (WBCs), monocytes, lymphocytes, neutrophils, basophils, and eosinophils) were examined in both the occupational workers and controls. In total, 370 occupational workers and 335 controls were compared. The analysis led to the following observations: (1) The average cumulative dose in males and females was 9.65±15.2 and 4.82±5.55 mSv, respectively. (2) In both males and females, there was a very low correlation between the occupation period and the cumulative dose (r<±0.25). (3) When the occupation period was longer, the WBC counts both decreased and increased in the male workers and the RBC counts were lower in the workers than in the control group (p<0.05). In females, the WBC counts both decreased and increased in the workers and the eosinophil counts were lower in the workers than in the control group (p<0.01). (4) When the cumulative dose was large, the lymphocyte counts decreased in male workers and the platelet count was lower in the workers than in the control group (p<0.05). In females, the lymphocyte count and RBC count were lower in the workers than in the control group (p<0.05). Abnormal distributions of some blood indices were observed in the occupational radiation workers compared with the controls. Attempts were made to limit radiation exposure to personnel, but the employees did not always follow the preset rules. Actually, the adverse effects of low-level radiation were attributed to probability. Overall, workers should obey the radiation protection regulations provided by the government and a national system of radiation protection is needed.

Reprint of 'Evaluation of Scattered Radiation Emitted From X-ray Security Scanners on Occupational Dose to Airport Personnel'

NASA Astrophysics Data System (ADS)

Dalah, Entesar; Fakhry, Angham; Mukhtar, Asma; Al Salti, Farah; Bader, May; Khouri, Sara; Al-Zahmi, Reem

2017-11-01

Based on security issues and regulations airports are provided with luggage cargo scanners. These scanners utilize ionizing radiation that in principle present health risks toward humans. The study aims to investigate the amount of backscatter produced by passenger luggage and cargo toward airport personnel who are located at different distances from the scanners. To approach our investigation a Thermo Electron Radeye-G probe was used to quantify the backscattered radiation measured in terms of dose-rate emitted from airport scanners, Measurements were taken at the entrance and exit positions of the X-ray tunnel at three different distances (0, 50, and 100 cm) for two different scanners; both scanners include shielding curtains that reduce scattered radiation. Correlation was demonstrated using the Pearson coefficient test. Measurements confirmed an inverse relationship between dose rate and distance. An estimated occupational accumulative dose of 0.88 mSv/y, and 2.04 mSv/y were obtained for personnel working in inspection of carry-on, and cargo, respectively. Findings confirm that the projected dose of security and engineering staff are being well within dose limits.

SOME PROBLEMS OF "SAFE DOSE" ESTIMATION

EPA Science Inventory

In environmental carcinogenic risk assessment, the usually defined "safe doses" appear subjective in some sense. n this paper a method of standardizing "safe doses" based on some objective parameters is introduced and a procedure of estimating safe doses under the competing risks...

Estimating occupancy dynamics in an anuran assemblage from Louisiana, USA

USGS Publications Warehouse

Walls, Susan C.; Waddle, J. Hardin; Dorazio, Robert M.

2011-01-01

Effective monitoring programs are designed to track changes in the distribution, occurrence, and abundance of species. We developed an extension of Royle and Kéry's (2007) single species model to estimate simultaneously temporal changes in probabilities of detection, occupancy, colonization, extinction, and species turnover using data on calling anuran amphibians, collected from 2002 to 2006 in the Lower Mississippi Alluvial Valley of Louisiana, USA. During our 5-year study, estimates of occurrence probabilities declined for all 12 species detected. These declines occurred primarily in conjunction with variation in estimates of local extinction probabilities (cajun chorus frog [Pseudacris fouquettei], spring peeper [P. crucifer], northern cricket frog [Acris crepitans], Cope's gray treefrog [Hyla chrysoscelis], green treefrog [H. cinerea], squirrel treefrog [H. squirella], southern leopard frog [Lithobates sphenocephalus], bronze frog [L. clamitans], American bullfrog [L. catesbeianus], and Fowler's toad [Anaxyrus fowleri]). For 2 species (eastern narrowmouthed toad [Gastrophryne carolinensis] and Gulf Coast toad [Incilius nebulifer]), declines in occupancy appeared to be a consequence of both increased local extinction and decreased colonization events. The eastern narrow-mouthed toad experienced a 2.5-fold increase in estimates of occupancy in 2004, possibly because of the high amount of rainfall received during that year, along with a decrease in extinction and increase in colonization of new sites between 2003 and 2004. Our model can be incorporated into monitoring programs to estimate simultaneously the occupancy dynamics for multiple species that show similar responses to ecological conditions. It will likely be an important asset for those monitoring programs that employ the same methods to sample assemblages of ecologically similar species, including those that are rare. By combining information from multiple species to decrease the variance on estimates

Development of a Job-Exposure Matrix (AsbJEM) to Estimate Occupational Exposure to Asbestos in Australia.

PubMed

van Oyen, Svein C; Peters, Susan; Alfonso, Helman; Fritschi, Lin; de Klerk, Nicholas H; Reid, Alison; Franklin, Peter; Gordon, Len; Benke, Geza; Musk, Arthur W

2015-07-01

Occupational exposure data on asbestos are limited and poorly integrated in Australia so that estimates of disease risk and attribution of disease causation are usually calculated from data that are not specific for local conditions. To develop a job-exposure matrix (AsbJEM) to estimate occupational asbestos exposure levels in Australia, making optimal use of the available exposure data. A dossier of all available exposure data in Australia and information on industry practices and controls was provided to an expert panel consisting of three local industrial hygienists with thorough knowledge of local and international work practices. The expert panel estimated asbestos exposures for combinations of occupation, industry, and time period. Intensity and frequency grades were estimated to enable the calculation of annual exposure levels for each occupation-industry combination for each time period. Two indicators of asbestos exposure intensity (mode and peak) were used to account for different patterns of exposure between occupations. Additionally, the probable type of asbestos fibre was determined for each situation. Asbestos exposures were estimated for 537 combinations of 224 occupations and 60 industries for four time periods (1943-1966; 1967-1986; 1987-2003; ≥2004). Workers in the asbestos manufacturing, shipyard, and insulation industries were estimated to have had the highest average exposures. Up until 1986, 46 occupation-industry combinations were estimated to have had exposures exceeding the current Australian exposure standard of 0.1 f ml(-1). Over 90% of exposed occupations were considered to have had exposure to a mixture of asbestos varieties including crocidolite. The AsbJEM provides empirically based quantified estimates of asbestos exposure levels for Australian jobs since 1943. This exposure assessment application will contribute to improved understanding and prediction of asbestos-related diseases and attribution of disease causation. © The

Dose-volume histogram prediction using density estimation.

PubMed

Skarpman Munter, Johanna; Sjölund, Jens

2015-09-07

Knowledge of what dose-volume histograms can be expected for a previously unseen patient could increase consistency and quality in radiotherapy treatment planning. We propose a machine learning method that uses previous treatment plans to predict such dose-volume histograms. The key to the approach is the framing of dose-volume histograms in a probabilistic setting.The training consists of estimating, from the patients in the training set, the joint probability distribution of some predictive features and the dose. The joint distribution immediately provides an estimate of the conditional probability of the dose given the values of the predictive features. The prediction consists of estimating, from the new patient, the distribution of the predictive features and marginalizing the conditional probability from the training over this. Integrating the resulting probability distribution for the dose yields an estimate of the dose-volume histogram.To illustrate how the proposed method relates to previously proposed methods, we use the signed distance to the target boundary as a single predictive feature. As a proof-of-concept, we predicted dose-volume histograms for the brainstems of 22 acoustic schwannoma patients treated with stereotactic radiosurgery, and for the lungs of 9 lung cancer patients treated with stereotactic body radiation therapy. Comparing with two previous attempts at dose-volume histogram prediction we find that, given the same input data, the predictions are similar.In summary, we propose a method for dose-volume histogram prediction that exploits the intrinsic probabilistic properties of dose-volume histograms. We argue that the proposed method makes up for some deficiencies in previously proposed methods, thereby potentially increasing ease of use, flexibility and ability to perform well with small amounts of training data.

78 FR 64030 - Monitoring Criteria and Methods To Calculate Occupational Radiation Doses

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-25

... NUCLEAR REGULATORY COMMISSION [NRC-2013-0234] Monitoring Criteria and Methods To Calculate... regulatory guide (DG), DG-8031, ``Monitoring Criteria and Methods to Calculate Occupational Radiation Doses.'' This guide describes methods that the NRC staff considers acceptable for licensees to use to determine...

Quantification of residual dose estimation error on log file-based patient dose calculation.

PubMed

Katsuta, Yoshiyuki; Kadoya, Noriyuki; Fujita, Yukio; Shimizu, Eiji; Matsunaga, Kenichi; Matsushita, Haruo; Majima, Kazuhiro; Jingu, Keiichi

2016-05-01

The log file-based patient dose estimation includes a residual dose estimation error caused by leaf miscalibration, which cannot be reflected on the estimated dose. The purpose of this study is to determine this residual dose estimation error. Modified log files for seven head-and-neck and prostate volumetric modulated arc therapy (VMAT) plans simulating leaf miscalibration were generated by shifting both leaf banks (systematic leaf gap errors: ±2.0, ±1.0, and ±0.5mm in opposite directions and systematic leaf shifts: ±1.0mm in the same direction) using MATLAB-based (MathWorks, Natick, MA) in-house software. The generated modified and non-modified log files were imported back into the treatment planning system and recalculated. Subsequently, the generalized equivalent uniform dose (gEUD) was quantified for the definition of the planning target volume (PTV) and organs at risks. For MLC leaves calibrated within ±0.5mm, the quantified residual dose estimation errors that obtained from the slope of the linear regression of gEUD changes between non- and modified log file doses per leaf gap are in head-and-neck plans 1.32±0.27% and 0.82±0.17Gy for PTV and spinal cord, respectively, and in prostate plans 1.22±0.36%, 0.95±0.14Gy, and 0.45±0.08Gy for PTV, rectum, and bladder, respectively. In this work, we determine the residual dose estimation errors for VMAT delivery using the log file-based patient dose calculation according to the MLC calibration accuracy. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Hard beta and gamma emissions of 124I. Impact on occupational dose in PET/CT.

PubMed

Kemerink, G J; Franssen, R; Visser, M G W; Urbach, C J A; Halders, S G E A; Frantzen, M J; Brans, B; Teule, G J J; Mottaghy, F M

2011-01-01

The hard beta and gamma radiation of 124I can cause high doses to PET/CT workers. In this study we tried to quantify this occupational exposure and to optimize radioprotection. Thin MCP-Ns thermoluminescent dosimeters suitable for measuring beta and gamma radiation were used for extremity dosimetry, active personal dosimeters for whole-body dosimetry. Extremity doses were determined during dispensing of 124I and oral administration of the activity to the patient, the body dose during all phases of the PET/CT procedure. In addition, dose rates of vials and syringes as used in clinical practice were measured. The procedure for dispensing 124I was optimized using newly developed shielding. Skin dose rates up to 100 mSv/min were measured when in contact with the manufacturer's vial containing 370 MBq of 124I. For an unshielded 5 ml syringe the positron skin dose was about seven times the gamma dose. Before optimization of the preparation of 124I, using an already reasonably safe technique, the highest mean skin dose caused by handling 370 MBq was 1.9 mSv (max. 4.4 mSv). After optimization the skin dose was below 0.2 mSv. The highly energetic positrons emitted by 124I can cause high skin doses if radioprotection is poor. Under optimized conditions occupational doses are acceptable. Education of workers is of paramount importance.

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

PubMed

O'Connor, U; Gallagher, A; Malone, L; O'Reilly, G

2013-02-01

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

Bayesian dose-response analysis for epidemiological studies with complex uncertainty in dose estimation.

PubMed

Kwon, Deukwoo; Hoffman, F Owen; Moroz, Brian E; Simon, Steven L

2016-02-10

Most conventional risk analysis methods rely on a single best estimate of exposure per person, which does not allow for adjustment for exposure-related uncertainty. Here, we propose a Bayesian model averaging method to properly quantify the relationship between radiation dose and disease outcomes by accounting for shared and unshared uncertainty in estimated dose. Our Bayesian risk analysis method utilizes multiple realizations of sets (vectors) of doses generated by a two-dimensional Monte Carlo simulation method that properly separates shared and unshared errors in dose estimation. The exposure model used in this work is taken from a study of the risk of thyroid nodules among a cohort of 2376 subjects who were exposed to fallout from nuclear testing in Kazakhstan. We assessed the performance of our method through an extensive series of simulations and comparisons against conventional regression risk analysis methods. When the estimated doses contain relatively small amounts of uncertainty, the Bayesian method using multiple a priori plausible draws of dose vectors gave similar results to the conventional regression-based methods of dose-response analysis. However, when large and complex mixtures of shared and unshared uncertainties are present, the Bayesian method using multiple dose vectors had significantly lower relative bias than conventional regression-based risk analysis methods and better coverage, that is, a markedly increased capability to include the true risk coefficient within the 95% credible interval of the Bayesian-based risk estimate. An evaluation of the dose-response using our method is presented for an epidemiological study of thyroid disease following radiation exposure. Copyright © 2015 John Wiley & Sons, Ltd.

Occupational dose reduction in cardiac catheterisation laboratory: a randomised trial using a shield drape placed on the patient.

PubMed

Ordiales, J M; Nogales, J M; Vano, E; López-Mínguez, J R; Alvarez, F J; Ramos, J; Martínez, G; Sánchez, R M

2017-04-25

The aim of this study was to evaluate the occupational radiation dose in interventional cardiology by using a shielding drape on the patient. A random study with and without the protective material was conducted. The following control parameters were registered: demographic data, number of stents, contrast media volume, fluoroscopy time, number of cine images, kerma-area product and cumulative air kerma. Occupational dose data were obtained by electronic active dosemeters. No statistically significant differences in the analysed control parameters were registered. The median dose value received by the interventional cardiologist was 50% lower in the group with a shielding drape with a statistically significant p-value <0.001. In addition, the median value of the maximum scatter radiation dose was 31% lower in this group with a statistically significant p-value <0.001. This study showed that a shielding drape is a useful tool for reducing the occupational radiation dose in a cardiac catheterisation laboratory. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Eye Lens Opacities Among Physicians Occupationally Exposed to Ionizing Radiation.

PubMed

Auvinen, Anssi; Kivelä, Tero; Heinävaara, Sirpa; Mrena, Samy

2015-08-01

We compared the frequency of lens opacities among physicians with and without occupational exposure to ionizing radiation, and estimated dose-response between cumulative dose and opacities. We conducted ophthalmologic examinations of 21 physicians with occupational exposure to radiation and 16 unexposed physicians. Information on cumulative radiation doses (mean 111 mSv) was based on dosimeter readings recorded in a national database on occupational exposures. Lens changes were evaluated using the Lens Opacities Classification System II, with an emphasis on posterior subcapsular (PSC) and cortical changes. Among the exposed physicians, the prevalences of cortical and PSC changes were both 11% (3/21), and the corresponding frequencies in the unexposed group were 44% (n = 7) and 6% (n = 1). For dose-response analysis, the data were pooled with 29 exposed physicians from our previous study. No association of either type of lens changes with cumulative recorded dose was observed. Our findings do not indicate an increased frequency of lens opacities in physicians with occupational exposure to ionizing radiation. However, the subjects in this study have received relatively low doses and therefore the results do not exclude small increases in lens opacities or contradict the studies reporting increases among interventional cardiologists with materially higher cumulative doses. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Linking occupancy surveys with habitat characteristics to estimate abundance and distribution in an endangered cryptic bird

USGS Publications Warehouse

Crampton, Lisa H.; Brinck, Kevin W.; Pias, Kyle E.; Heindl, Barbara A. P.; Savre, Thomas; Diegmann, Julia S.; Paxton, Eben H.

2017-01-01

Accurate estimates of the distribution and abundance of endangered species are crucial to determine their status and plan recovery options, but such estimates are often difficult to obtain for species with low detection probabilities or that occur in inaccessible habitats. The Puaiohi (Myadestes palmeri) is a cryptic species endemic to Kauaʻi, Hawai‘i, and restricted to high elevation ravines that are largely inaccessible. To improve current population estimates, we developed an approach to model distribution and abundance of Puaiohi across their range by linking occupancy surveys to habitat characteristics, territory density, and landscape attributes. Occupancy per station ranged from 0.17 to 0.82, and was best predicted by the number and vertical extent of cliffs, cliff slope, stream width, and elevation. To link occupancy estimates with abundance, we used territory mapping data to estimate the average number of territories per survey station (0.44 and 0.66 territories per station in low and high occupancy streams, respectively), and the average number of individuals per territory (1.9). We then modeled Puaiohi occupancy as a function of two remote-sensed measures of habitat (stream sinuosity and elevation) to predict occupancy across its entire range. We combined predicted occupancy with estimates of birds per station to produce a global population estimate of 494 (95% CI 414–580) individuals. Our approach is a model for using multiple independent sources of information to accurately track population trends, and we discuss future directions for modeling abundance of this, and other, rare species.

Estimated radiation exposure of German commercial airline cabin crew in the years 1960-2003 modeled using dose registry data for 2004-2015.

PubMed

Wollschläger, Daniel; Hammer, Gaël Paul; Schafft, Thomas; Dreger, Steffen; Blettner, Maria; Zeeb, Hajo

2018-05-01

Exposure to ionizing radiation of cosmic origin is an occupational risk factor in commercial aircrew. In a historic cohort of 26,774 German aircrew, radiation exposure was previously estimated only for cockpit crew using a job-exposure matrix (JEM). Here, a new method for retrospectively estimating cabin crew dose is developed. The German Federal Radiation Registry (SSR) documents individual monthly effective doses for all aircrew. SSR-provided doses on 12,941 aircrew from 2004 to 2015 were used to model cabin crew dose as a function of age, sex, job category, solar activity, and male pilots' dose; the mean annual effective dose was 2.25 mSv (range 0.01-6.39 mSv). In addition to an inverse association with solar activity, exposure followed age- and sex-dependent patterns related to individual career development and life phases. JEM-derived annual cockpit crew doses agreed with SSR-provided doses for 2004 (correlation 0.90, 0.40 mSv root mean squared error), while the estimated average annual effective dose for cabin crew had a prediction error of 0.16 mSv, equaling 7.2% of average annual dose. Past average annual cabin crew dose can be modeled by exploiting systematic external influences as well as individual behavioral determinants of radiation exposure, thereby enabling future dose-response analyses of the full aircrew cohort including measurement error information.

Meta-analysis on occupational exposure to pesticides--neurobehavioral impact and dose-response relationships.

PubMed

Meyer-Baron, Monika; Knapp, Guido; Schäper, Michael; van Thriel, Christoph

2015-01-01

While the health impact of high exposures to pesticides is acknowledged, the impact of chronic exposures in the absence of acute poisonings is controversial. A systematic analysis of dose-response relationships is still missing. Its absence may provoke alternative explanations for altered performances. Consequently, opportunities for health prevention in the occupational and environmental field may be missed. Objectives were (1) quantification of the neurotoxic impact of pesticides by an analysis of functional alterations in workers measured by neuropsychological performance tests, (2) estimates of dose-response relationships on the basis of exposure duration, and (3) exploration of susceptible subgroups. The meta-analysis employed a random effects model to obtain overall effects for individual performance tests. Twenty-two studies with a total of 1758 exposed and 1260 reference individuals met the inclusion criteria. At least three independent outcomes were available for twenty-six performance variables. Significant performance effects were shown in adults and referred to both cognitive and motor performances. Effect sizes ranging from dRE=-0.14 to dRE=-0.67 showed consistent outcomes for memory and attention. Relationships between effect sizes and exposure duration were indicated for individual performance variables and the total of measured performances. Studies on adolescents had to be analyzed separately due to numerous outliers. The large variation among outcomes hampered the analysis of the susceptibility in this group, while data on female workers was too scant for the analysis. Relationships exist between the impact of pesticides on performances and exposure duration. A change in test paradigms would help to decipher the impact more specifically. The use of biomarkers appropriate for lower exposures would allow a better prevention of neurotoxic effects due to occupational and environmental exposure. Intervention studies in adolescents seem warranted to

Influences of Availability on Parameter Estimates from Site Occupancy Models with Application to Submersed Aquatic Vegetation

USGS Publications Warehouse

Gray, Brian R.; Holland, Mark D.; Yi, Feng; Starcevich, Leigh Ann Harrod

2013-01-01

Site occupancy models are commonly used by ecologists to estimate the probabilities of species site occupancy and of species detection. This study addresses the influence on site occupancy and detection estimates of variation in species availability among surveys within sites. Such variation in availability may result from temporary emigration, nonavailability of the species for detection, and sampling sites spatially when species presence is not uniform within sites. We demonstrate, using Monte Carlo simulations and aquatic vegetation data, that variation in availability and heterogeneity in the probability of availability may yield biases in the expected values of the site occupancy and detection estimates that have traditionally been associated with low-detection probabilities and heterogeneity in those probabilities. These findings confirm that the effects of availability may be important for ecologists and managers, and that where such effects are expected, modification of sampling designs and/or analytical methods should be considered. Failure to limit the effects of availability may preclude reliable estimation of the probability of site occupancy.

Fast skin dose estimation system for interventional radiology

PubMed Central

Takata, Takeshi; Kotoku, Jun’ichi; Maejima, Hideyuki; Kumagai, Shinobu; Arai, Norikazu; Kobayashi, Takenori; Shiraishi, Kenshiro; Yamamoto, Masayoshi; Kondo, Hiroshi; Furui, Shigeru

2018-01-01

Abstract To minimise the radiation dermatitis related to interventional radiology (IR), rapid and accurate dose estimation has been sought for all procedures. We propose a technique for estimating the patient skin dose rapidly and accurately using Monte Carlo (MC) simulation with a graphical processing unit (GPU, GTX 1080; Nvidia Corp.). The skin dose distribution is simulated based on an individual patient’s computed tomography (CT) dataset for fluoroscopic conditions after the CT dataset has been segmented into air, water and bone based on pixel values. The skin is assumed to be one layer at the outer surface of the body. Fluoroscopic conditions are obtained from a log file of a fluoroscopic examination. Estimating the absorbed skin dose distribution requires calibration of the dose simulated by our system. For this purpose, a linear function was used to approximate the relation between the simulated dose and the measured dose using radiophotoluminescence (RPL) glass dosimeters in a water-equivalent phantom. Differences of maximum skin dose between our system and the Particle and Heavy Ion Transport code System (PHITS) were as high as 6.1%. The relative statistical error (2 σ) for the simulated dose obtained using our system was ≤3.5%. Using a GPU, the simulation on the chest CT dataset aiming at the heart was within 3.49 s on average: the GPU is 122 times faster than a CPU (Core i7–7700K; Intel Corp.). Our system (using the GPU, the log file, and the CT dataset) estimated the skin dose more rapidly and more accurately than conventional methods. PMID:29136194

Fast skin dose estimation system for interventional radiology.

PubMed

Takata, Takeshi; Kotoku, Jun'ichi; Maejima, Hideyuki; Kumagai, Shinobu; Arai, Norikazu; Kobayashi, Takenori; Shiraishi, Kenshiro; Yamamoto, Masayoshi; Kondo, Hiroshi; Furui, Shigeru

2018-03-01

To minimise the radiation dermatitis related to interventional radiology (IR), rapid and accurate dose estimation has been sought for all procedures. We propose a technique for estimating the patient skin dose rapidly and accurately using Monte Carlo (MC) simulation with a graphical processing unit (GPU, GTX 1080; Nvidia Corp.). The skin dose distribution is simulated based on an individual patient's computed tomography (CT) dataset for fluoroscopic conditions after the CT dataset has been segmented into air, water and bone based on pixel values. The skin is assumed to be one layer at the outer surface of the body. Fluoroscopic conditions are obtained from a log file of a fluoroscopic examination. Estimating the absorbed skin dose distribution requires calibration of the dose simulated by our system. For this purpose, a linear function was used to approximate the relation between the simulated dose and the measured dose using radiophotoluminescence (RPL) glass dosimeters in a water-equivalent phantom. Differences of maximum skin dose between our system and the Particle and Heavy Ion Transport code System (PHITS) were as high as 6.1%. The relative statistical error (2 σ) for the simulated dose obtained using our system was ≤3.5%. Using a GPU, the simulation on the chest CT dataset aiming at the heart was within 3.49 s on average: the GPU is 122 times faster than a CPU (Core i7-7700K; Intel Corp.). Our system (using the GPU, the log file, and the CT dataset) estimated the skin dose more rapidly and more accurately than conventional methods.

42 CFR 82.3 - What Are the Requirements for Dose Reconstruction Under EEOICPA?

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES METHODS FOR CONDUCTING DOSE... unrecorded doses, which are estimated using commonly practiced dose reconstruction methods and would have to...

A Bayesian Machine Learning Model for Estimating Building Occupancy from Open Source Data

DOE PAGES

Stewart, Robert N.; Urban, Marie L.; Duchscherer, Samantha E.; ...

2016-01-01

Understanding building occupancy is critical to a wide array of applications including natural hazards loss analysis, green building technologies, and population distribution modeling. Due to the expense of directly monitoring buildings, scientists rely in addition on a wide and disparate array of ancillary and open source information including subject matter expertise, survey data, and remote sensing information. These data are fused using data harmonization methods which refer to a loose collection of formal and informal techniques for fusing data together to create viable content for building occupancy estimation. In this paper, we add to the current state of the artmore » by introducing the Population Data Tables (PDT), a Bayesian based informatics system for systematically arranging data and harmonization techniques into a consistent, transparent, knowledge learning framework that retains in the final estimation uncertainty emerging from data, expert judgment, and model parameterization. PDT probabilistically estimates ambient occupancy in units of people/1000ft2 for over 50 building types at the national and sub-national level with the goal of providing global coverage. The challenge of global coverage led to the development of an interdisciplinary geospatial informatics system tool that provides the framework for capturing, storing, and managing open source data, handling subject matter expertise, carrying out Bayesian analytics as well as visualizing and exporting occupancy estimation results. We present the PDT project, situate the work within the larger community, and report on the progress of this multi-year project.Understanding building occupancy is critical to a wide array of applications including natural hazards loss analysis, green building technologies, and population distribution modeling. Due to the expense of directly monitoring buildings, scientists rely in addition on a wide and disparate array of ancillary and open source information

Occupational exposure to radon for underground tourist routes in Poland: Doses to lung and the risk of developing lung cancer.

PubMed

Walczak, Katarzyna; Olszewski, Jerzy; Politański, Piotr; Zmyślony, Marek

2017-07-14

Radon concentrations for 31 Polish underground tourist routes were analyzed. The equivalent dose to the lung, the effective dose and the relative risk were calculated for employees of the analyzed routes on the grounds of information on radon concentrations, work time, etc. The relative risk for lung cancers was calculated using the Biological Effects of Ionizing Radiation (BEIR) VI Committee model. Equivalent doses to the lungs of workers were determined using the coefficients calculated by the Kendall and Smith. The conversion coefficient proposed by the International Atomic Energy Agency (IAEA) in the report No. 33 was used for estimating the effective doses. In 13 routes, the effective dose was found to be above 1 mSv/year, and in 3 routes, it exceeded 6 mSv/year. For 5 routes, the equivalent dose to lungs was higher than 100 mSv/year, and in 1 case it was as high as 490 mSv/year. In 22.6% of underground workplaces the risk of developing lung cancer among employees was about 2 times higher than that for the general population, and for 1 tourist route it was about 5 times higher. The geometric mean of the relative risk of lung cancer for all workers of underground tourist routes was 1.73 (95% confidence interval (CI): 1.6-1.87). Routes were divided into: caves, mines, post-military underground constructions and urban underground constructions. The difference between levels of the relative risk of developing lung cancer for all types of underground tourist routes was not found to be significant. If we include the professional group of the employees of underground tourist routes into the group of occupational exposure, the number of persons who are included in the Category A due to occupational exposure may increase by about 3/4. The professional group of the employees of underground tourist routes should be monitored for their exposure to radon. Int J Occup Med Environ Health 2017;30(5):687-694. This work is available in Open Access model and licensed under a CC

42 CFR 82.26 - How will NIOSH report dose reconstruction results?

Code of Federal Regulations, 2014 CFR

2014-10-01

... OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER... dose reconstruction, justification for the decision, and if possible, a quantitative estimate of the...

42 CFR 82.26 - How will NIOSH report dose reconstruction results?

Code of Federal Regulations, 2010 CFR

2010-10-01

... OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER... dose reconstruction, justification for the decision, and if possible, a quantitative estimate of the...

42 CFR 82.26 - How will NIOSH report dose reconstruction results?

Code of Federal Regulations, 2012 CFR

2012-10-01

... OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER... dose reconstruction, justification for the decision, and if possible, a quantitative estimate of the...

42 CFR 82.26 - How will NIOSH report dose reconstruction results?

Code of Federal Regulations, 2013 CFR

2013-10-01

... OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER... dose reconstruction, justification for the decision, and if possible, a quantitative estimate of the...

42 CFR 82.26 - How will NIOSH report dose reconstruction results?

Code of Federal Regulations, 2011 CFR

2011-10-01

... OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER... dose reconstruction, justification for the decision, and if possible, a quantitative estimate of the...

Advances in Inhalation Dosimetry Models and Methods for Occupational Risk Assessment and Exposure Limit Derivation

PubMed Central

Kuempel, Eileen D.; Sweeney, Lisa M.; Morris, John B.; Jarabek, Annie M.

2015-01-01

The purpose of this article is to provide an overview and practical guide to occupational health professionals concerning the derivation and use of dose estimates in risk assessment for development of occupational exposure limits (OELs) for inhaled substances. Dosimetry is the study and practice of measuring or estimating the internal dose of a substance in individuals or a population. Dosimetry thus provides an essential link to understanding the relationship between an external exposure and a biological response. Use of dosimetry principles and tools can improve the accuracy of risk assessment, and reduce the uncertainty, by providing reliable estimates of the internal dose at the target tissue. This is accomplished through specific measurement data or predictive models, when available, or the use of basic dosimetry principles for broad classes of materials. Accurate dose estimation is essential not only for dose-response assessment, but also for interspecies extrapolation and for risk characterization at given exposures. Inhalation dosimetry is the focus of this paper since it is a major route of exposure in the workplace. Practical examples of dose estimation and OEL derivation are provided for inhaled gases and particulates. PMID:26551218

The effect of rate denominator source on US fatal occupational injury rate estimates.

PubMed

Richardson, David; Loomis, Dana; Bailer, A John; Bena, James

2004-09-01

The Current Population Survey (CPS) is often used as a source of denominator information for analyses of US fatal occupational injury rates. However, given the relatively small sample size of the CPS, analyses that examine the cross-classification of occupation or industry with demographic or geographic characteristics will often produce highly imprecise rate estimates. The Decennial Census of Population provides an alternative source for rate denominator information. We investigate the comparability of fatal injury rates derived using these two sources of rate denominator information. Information on fatal occupational injuries that occurred between January 1, 1983 and December 31, 1994 was obtained from the National Traumatic Occupational Fatality surveillance system. Annual estimates of employment by occupation, industry, age, and sex were derived from the CPS, and by linear interpolation and extrapolation from the 1980 and 1990 Census of Population. Fatal injury rates derived using these denominator data were compared. Fatal injury rates calculated using Census-based denominator data were within 10% of rates calculated using CPS data for all major occupation groups except farming/forestry/fishing, for which the fatal injury rate calculated using Census-based denominator data was 24.69/100,000 worker-years and the rate calculated using CPS data was 19.97/100,000 worker-years. The choice of denominator data source had minimal influence on estimates of trends over calendar time in the fatal injury rates for most major occupation and industry groups. The Census offers a reasonable source for deriving fatal injury rate denominator data in situations where the CPS does not provide sufficiently precise data, although the Census may underestimate the population-at-risk in some industries as a consequence of seasonal variation in employment.

Comparing estimates of population change from occupancy and mark-recapture models for a territorial species

Treesearch

Mary M. Conner; John J. Keane; Claire V. Gallagher; Thomas E. Munton; Paula A. Shaklee

2016-01-01

Monitoring studies often use marked animals to estimate population abundance at small spatial scales. However, at smaller scales, occupancy sampling, which uses detection/nondetection data, may be useful where sites are approximately territories, and occupancy dynamics should be strongly correlated with population dynamics. Occupancy monitoring has advantages...

Dose — response relationship between noise exposure and the risk of occupational injury

PubMed Central

Yoon, Jin-Ha; Hong, Jeong-Suk; Roh, Jaehoon; Kim, Chi-Nyon; Won, Jong-Uk

2015-01-01

Many workers worldwide experience fatality and disability caused by occupational injuries. This study examined the relationship between noise exposure and occupational injuries at factories in Korea. A total of 1790 factories located in northern Gyeonggi Province, Korea was evaluated. The time-weighted average levels of dust and noise exposure were taken from Workplace Exposure Assessment data. Apart occupational injuries, sports events, traffic accidents, and other accidents occurring outside workplaces were excluded. The incidences of occupational injury in each factory were calculated by data from the Korea Workers’ Compensation and Welfare Services. Workplaces were classified according to the incidence of any occupational injuries (incident or nonincident workplaces, respectively). Workplace dust exposure was classified as <1 or ≥1 mg/m3, and noise exposure as <80, 80-89, or >90 dB. Workplaces with high noise exposure were significantly associated with being incident workplaces, whereas workplaces with high dust exposure were not. The odds ratios (95% confidence intervals) derived from a logistic regression model were 1.68 (1.27-2.24) and 3.42 (2.26-5.17) at 80-89 dB and ≥90 dB versus <80 dB. These associations remained significant when in a separate analysis according to high or low dust exposure level. Noise exposure increases the risk of occupational injury in the workplace. Furthermore, the risk of occupational injury increases with noise exposure level in a dose-response relationship. Therefore, strategies for reducing noise exposure level are required to decrease the risk of occupational injury. PMID:25599757

Estimating site occupancy rates for aquatic plants using spatial sub-sampling designs when detection probabilities are less than one

USGS Publications Warehouse

Nielson, Ryan M.; Gray, Brian R.; McDonald, Lyman L.; Heglund, Patricia J.

2011-01-01

Estimation of site occupancy rates when detection probabilities are <1 is well established in wildlife science. Data from multiple visits to a sample of sites are used to estimate detection probabilities and the proportion of sites occupied by focal species. In this article we describe how site occupancy methods can be applied to estimate occupancy rates of plants and other sessile organisms. We illustrate this approach and the pitfalls of ignoring incomplete detection using spatial data for 2 aquatic vascular plants collected under the Upper Mississippi River's Long Term Resource Monitoring Program (LTRMP). Site occupancy models considered include: a naïve model that ignores incomplete detection, a simple site occupancy model assuming a constant occupancy rate and a constant probability of detection across sites, several models that allow site occupancy rates and probabilities of detection to vary with habitat characteristics, and mixture models that allow for unexplained variation in detection probabilities. We used information theoretic methods to rank competing models and bootstrapping to evaluate the goodness-of-fit of the final models. Results of our analysis confirm that ignoring incomplete detection can result in biased estimates of occupancy rates. Estimates of site occupancy rates for 2 aquatic plant species were 19–36% higher compared to naive estimates that ignored probabilities of detection <1. Simulations indicate that final models have little bias when 50 or more sites are sampled, and little gains in precision could be expected for sample sizes >300. We recommend applying site occupancy methods for monitoring presence of aquatic species.

Dose-Response Relationship between Cumulative Occupational Lead Exposure and the Associated Health Damages: A 20-Year Cohort Study of a Smelter in China

PubMed Central

Wu, Yue; Gu, Jun-Ming; Huang, Yun; Duan, Yan-Ying; Huang, Rui-Xue; Hu, Jian-An

2016-01-01

Long-term airborne lead exposure, even below official occupational limits, has been found to cause lead poisoning at higher frequencies than expected, which suggests that China’s existing occupational exposure limits should be reexamined. A retrospective cohort study was conducted on 1832 smelting workers from 1988 to 2008 in China. These were individuals who entered the plant and came into continuous contact with lead at work for longer than 3 months. The dose-response relationship between occupational cumulative lead exposure and lead poisoning, abnormal blood lead, urinary lead and erythrocyte zinc protoporphyrin (ZPP) were analyzed and the benchmark dose lower bound confidence limits (BMDLs) were calculated. Statistically significant positive correlations were found between cumulative lead dust and lead fumes exposures and workplace seniority, blood lead, urinary lead and ZPP values. A dose-response relationship was observed between cumulative lead dust or lead fumes exposure and lead poisoning (p < 0.01). The BMDLs of the cumulative occupational lead dust and fumes doses were 0.68 mg-year/m3 and 0.30 mg-year/m3 for lead poisoning, respectively. The BMDLs of workplace airborne lead concentrations associated with lead poisoning were 0.02 mg/m3 and 0.01 mg/m3 for occupational exposure lead dust and lead fume, respectively. In conclusion, BMDLs for airborne lead were lower than occupational exposure limits, suggesting that the occupational lead exposure limits need re-examination and adjustment. Occupational cumulative exposure limits (OCELs) should be established to better prevent occupational lead poisoning. PMID:26999177

Nonparametric estimation of benchmark doses in environmental risk assessment

PubMed Central

Piegorsch, Walter W.; Xiong, Hui; Bhattacharya, Rabi N.; Lin, Lizhen

2013-01-01

Summary An important statistical objective in environmental risk analysis is estimation of minimum exposure levels, called benchmark doses (BMDs), that induce a pre-specified benchmark response in a dose-response experiment. In such settings, representations of the risk are traditionally based on a parametric dose-response model. It is a well-known concern, however, that if the chosen parametric form is misspecified, inaccurate and possibly unsafe low-dose inferences can result. We apply a nonparametric approach for calculating benchmark doses, based on an isotonic regression method for dose-response estimation with quantal-response data (Bhattacharya and Kong, 2007). We determine the large-sample properties of the estimator, develop bootstrap-based confidence limits on the BMDs, and explore the confidence limits’ small-sample properties via a short simulation study. An example from cancer risk assessment illustrates the calculations. PMID:23914133

The effect of voice amplification on occupational vocal dose in elementary school teachers.

PubMed

Gaskill, Christopher S; O'Brien, Shenendoah G; Tinter, Sara R

2012-09-01

Two elementary school teachers, one with and one without a history of vocal complaints, wore a vocal dosimeter all day at school for a 3-week period. In the second week, each teacher wore a portable voice amplifier. Each teacher showed a reduction in vocal intensity during the week of amplification, with a larger effect for the teacher with vocal difficulties. This teacher also showed a decrease in hourly vocal fold distance dose as measured by the dosimeter despite incurring longer phonation times. Fundamental frequency and vocal fold cycle dose did not appear to be affected by the use of amplification during the teaching day. Both teachers showed evidence of a possible moderate effect of adjusting vocal intensity in the week after amplification, possibly as a means to recalibrate their perceived vocal loudness. This study demonstrates the usefulness of both vocal dosimetry and amplification in monitoring and modifying vocal dose in an occupational setting and reinforces previous data suggesting the effectiveness of amplification in reducing the vocal load in schoolteachers. Implications of the data for future research regarding prevention and treatment of occupational voice disorders are discussed. Copyright © 2012 The Voice Foundation. Published by Mosby, Inc. All rights reserved.

SU-F-P-19: Fetal Dose Estimate for a High-Dose Fluoroscopy Guided Intervention Using Modern Data Tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moirano, J

Purpose: An accurate dose estimate is necessary for effective patient management after a fetal exposure. In the case of a high-dose exposure, it is critical to use all resources available in order to make the most accurate assessment of the fetal dose. This work will demonstrate a methodology for accurate fetal dose estimation using tools that have recently become available in many clinics, and show examples of best practices for collecting data and performing the fetal dose calculation. Methods: A fetal dose estimate calculation was performed using modern data collection tools to determine parameters for the calculation. The reference pointmore » air kerma as displayed by the fluoroscopic system was checked for accuracy. A cumulative dose incidence map and DICOM header mining were used to determine the displayed reference point air kerma. Corrections for attenuation caused by the patient table and pad were measured and applied in order to determine the peak skin dose. The position and depth of the fetus was determined by ultrasound imaging and consultation with a radiologist. The data collected was used to determine a normalized uterus dose from Monte Carlo simulation data. Fetal dose values from this process were compared to other accepted calculation methods. Results: An accurate high-dose fetal dose estimate was made. Comparison to accepted legacy methods were were within 35% of estimated values. Conclusion: Modern data collection and reporting methods ease the process for estimation of fetal dose from interventional fluoroscopy exposures. Many aspects of the calculation can now be quantified rather than estimated, which should allow for a more accurate estimation of fetal dose.« less

Dose conversion factors for radon: recent developments.

PubMed

Marsh, James W; Harrison, John D; Laurier, Dominique; Blanchardon, Eric; Paquet, François; Tirmarche, Margot

2010-10-01

Epidemiological studies of the occupational exposure of miners and domestic exposures of the public have provided strong and complementary evidence of the risks of lung cancer following inhalation of radon progeny. Recent miner epidemiological studies, which include low levels of exposure, long duration of follow-up, and good quality of individual exposure data, suggest higher risks of lung cancer per unit exposure than assumed previously by the International Commission on Radiological Protection (ICRP). Although risks can be managed by controlling exposures, dose estimates are required for the control of occupational exposures and are also useful for comparing sources of public exposure. Currently, ICRP calculates doses from radon and its progeny using dose conversion factors from exposure (WLM) to dose (mSv) based on miner epidemiological studies, referred to as the epidemiological approach. Revision of these dose conversion factors using risk estimates based on the most recent epidemiological data gives values that are in good agreement with the results of calculations using ICRP biokinetic and dosimetric models, the dosimetric approach. ICRP now proposes to treat radon progeny in the same way as other radionuclides and to publish dose coefficients calculated using models, for use within the ICRP system of protection.

Bayesian estimation of dose thresholds

NASA Technical Reports Server (NTRS)

Groer, P. G.; Carnes, B. A.

2003-01-01

An example is described of Bayesian estimation of radiation absorbed dose thresholds (subsequently simply referred to as dose thresholds) using a specific parametric model applied to a data set on mice exposed to 60Co gamma rays and fission neutrons. A Weibull based relative risk model with a dose threshold parameter was used to analyse, as an example, lung cancer mortality and determine the posterior density for the threshold dose after single exposures to 60Co gamma rays or fission neutrons from the JANUS reactor at Argonne National Laboratory. The data consisted of survival, censoring times and cause of death information for male B6CF1 unexposed and exposed mice. The 60Co gamma whole-body doses for the two exposed groups were 0.86 and 1.37 Gy. The neutron whole-body doses were 0.19 and 0.38 Gy. Marginal posterior densities for the dose thresholds for neutron and gamma radiation were calculated with numerical integration and found to have quite different shapes. The density of the threshold for 60Co is unimodal with a mode at about 0.50 Gy. The threshold density for fission neutrons declines monotonically from a maximum value at zero with increasing doses. The posterior densities for all other parameters were similar for the two radiation types.

A Web-Based System for Bayesian Benchmark Dose Estimation.

PubMed

Shao, Kan; Shapiro, Andrew J

2018-01-11

Benchmark dose (BMD) modeling is an important step in human health risk assessment and is used as the default approach to identify the point of departure for risk assessment. A probabilistic framework for dose-response assessment has been proposed and advocated by various institutions and organizations; therefore, a reliable tool is needed to provide distributional estimates for BMD and other important quantities in dose-response assessment. We developed an online system for Bayesian BMD (BBMD) estimation and compared results from this software with U.S. Environmental Protection Agency's (EPA's) Benchmark Dose Software (BMDS). The system is built on a Bayesian framework featuring the application of Markov chain Monte Carlo (MCMC) sampling for model parameter estimation and BMD calculation, which makes the BBMD system fundamentally different from the currently prevailing BMD software packages. In addition to estimating the traditional BMDs for dichotomous and continuous data, the developed system is also capable of computing model-averaged BMD estimates. A total of 518 dichotomous and 108 continuous data sets extracted from the U.S. EPA's Integrated Risk Information System (IRIS) database (and similar databases) were used as testing data to compare the estimates from the BBMD and BMDS programs. The results suggest that the BBMD system may outperform the BMDS program in a number of aspects, including fewer failed BMD and BMDL calculations and estimates. The BBMD system is a useful alternative tool for estimating BMD with additional functionalities for BMD analysis based on most recent research. Most importantly, the BBMD has the potential to incorporate prior information to make dose-response modeling more reliable and can provide distributional estimates for important quantities in dose-response assessment, which greatly facilitates the current trend for probabilistic risk assessment. https://doi.org/10.1289/EHP1289.

beta- and gamma-Comparative dose estimates on Enewetak Atoll.

PubMed

Crase, K W; Gudiksen, P H; Robison, W L

1982-05-01

Enewetak Atoll is one of the Pacific atolls used for atmospheric testing of U.S. nuclear weapons. Beta dose and gamma-ray exposure measurements were made on two islands of the Enewetak Atoll during July-August 1976 to determine the beta and low energy gamma-contribution to the total external radiation doses to the returning Marshallese. Measurements were made at numerous locations with thermoluminescent dosimeters (TLD), pressurized ionization chambers, portable NaI detectors, and thin-window pancake GM probes. Results of the TLD measurements with and without a beta-attenuator indicate that approx. 29% of the total dose rate at 1 m in air is due to beta- or low energy gamma-contribution. The contribution at any particular site, however, is somewhat dependent on ground cover, since a minimal amount of vegetation will reduce it significantly from that over bare soil, but thick stands of vegetation have little effect on any further reductions. Integral 30-yr external shallow dose estimates for future inhabitants were made and compared with external dose estimates of a previous large scale radiological survey (En73). Integral 30-yr shallow external dose estimates are 25-50% higher than whole body estimates. Due to the low penetrating ability of the beta's or low energy gamma's, however, several remedial actions can be taken to reduce the shallow dose contribution to the total external dose.

Occupational injury and illness in the United States. Estimates of costs, morbidity, and mortality.

PubMed

Leigh, J P; Markowitz, S B; Fahs, M; Shin, C; Landrigan, P J

1997-07-28

To estimate the annual incidence, the mortality and the direct and indirect costs associated with occupational injuries and illnesses in the United States in 1992. Aggregation and analysis of national and large regional data sets collected by the Bureau of Labor Statistics, the National Council on Compensation Insurance, the National Center for Health Statistics, the Health Care Financing Administration, and other governmental bureaus and private firms. To assess incidence of and mortality from occupational injuries and illnesses, we reviewed data from national surveys and applied an attributable risk proportion method. To assess costs, we used the human capital method that decomposes costs into direct categories such as medical and insurance administration expenses as well as indirect categories such as lost earnings, lost home production, and lost fringe benefits. Some cost estimates were drawn from the literature while others were generated within this study. Total costs were calculated by multiplying average costs by the number of injuries and illnesses in each diagnostic category. Approximately 6500 job-related deaths from injury, 13.2 million nonfatal injuries, 60,300 deaths from disease, and 862,200 illnesses are estimated to occur annually in the civilian American workforce. The total direct ($65 billion) plus indirect ($106 billion) costs were estimated to be $171 billion. Injuries cost $145 billion and illnesses $26 billion. These estimates are likely to be low, because they ignore costs associated with pain and suffering as well as those of within-home care provided by family members, and because the numbers of occupational injuries and illnesses are likely to be undercounted. The costs of occupational injuries and illnesses are high, in sharp contrast to the limited public attention and societal resources devoted to their prevention and amelioration. Occupational injuries and illnesses are an insufficiently appreciated contributor to the total burden of

Convolution-based estimation of organ dose in tube current modulated CT

NASA Astrophysics Data System (ADS)

Tian, Xiaoyu; Segars, W. Paul; Dixon, Robert L.; Samei, Ehsan

2016-05-01

Estimating organ dose for clinical patients requires accurate modeling of the patient anatomy and the dose field of the CT exam. The modeling of patient anatomy can be achieved using a library of representative computational phantoms (Samei et al 2014 Pediatr. Radiol. 44 460-7). The modeling of the dose field can be challenging for CT exams performed with a tube current modulation (TCM) technique. The purpose of this work was to effectively model the dose field for TCM exams using a convolution-based method. A framework was further proposed for prospective and retrospective organ dose estimation in clinical practice. The study included 60 adult patients (age range: 18-70 years, weight range: 60-180 kg). Patient-specific computational phantoms were generated based on patient CT image datasets. A previously validated Monte Carlo simulation program was used to model a clinical CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). A practical strategy was developed to achieve real-time organ dose estimation for a given clinical patient. CTDIvol-normalized organ dose coefficients ({{h}\\text{Organ}} ) under constant tube current were estimated and modeled as a function of patient size. Each clinical patient in the library was optimally matched to another computational phantom to obtain a representation of organ location/distribution. The patient organ distribution was convolved with a dose distribution profile to generate {{≤ft(\\text{CTD}{{\\text{I}}\\text{vol}}\\right)}\\text{organ, \\text{convolution}}} values that quantified the regional dose field for each organ. The organ dose was estimated by multiplying {{≤ft(\\text{CTD}{{\\text{I}}\\text{vol}}\\right)}\\text{organ, \\text{convolution}}} with the organ dose coefficients ({{h}\\text{Organ}} ). To validate the accuracy of this dose estimation technique, the organ dose of the original clinical patient was estimated using Monte Carlo program with TCM profiles explicitly modeled. The

The application of drug dose equivalence in the quantitative analysis of receptor occupation and drug combinations

PubMed Central

Tallarida, Ronald J.; Raffa, Robert B.

2014-01-01

In this review we show that the concept of dose equivalence for two drugs, the theoretical basis of the isobologram, has a wider use in the analysis of pharmacological data derived from single and combination drug use. In both its application to drug combination analysis with isoboles and certain other actions, listed below, the determination of doses, or receptor occupancies, that yield equal effects provide useful metrics that can be used to obtain quantitative information on drug actions without postulating any intimate mechanism of action. These other drug actions discussed here include (1) combinations of agonists that produce opposite effects, (2) analysis of inverted U-shaped dose effect curves of single agents, (3) analysis on the effect scale as an alternative to isoboles and (4) the use of occupation isoboles to examine competitive antagonism in the dual receptor case. New formulas derived to assess the statistical variance for additive combinations are included, and the more detailed mathematical topics are included in the appendix. PMID:20546783

Estimating occupancy dynamics for large-scale monitoring networks: amphibian breeding occupancy across protected areas in the northeast United States

USGS Publications Warehouse

Miller, David A.W.; Grant, Evan H. Campbell

2015-01-01

Regional monitoring strategies frequently employ a nested sampling design where a finite set of study areas from throughout a region are selected within which intensive sub-sampling occurs. This sampling protocol naturally lends itself to a hierarchical analysis to account for dependence among sub-samples. Implementing such an analysis within a classic likelihood framework is computationally prohibitive with species occurrence data when accounting for detection probabilities. Bayesian methods offer an alternative framework to make this analysis feasible. We demonstrate a general approach for estimating occupancy when data come from a nested sampling design. Using data from a regional monitoring program of wood frogs (Lithobates sylvaticus) and spotted salamanders (Ambystoma maculatum) in vernal pools, we analyzed data using static and dynamic occupancy frameworks. We analyzed observations from 2004-2013collected within 14 protected areas located throughout the northeast United States . We use the data set to estimate trends in occupancy at both the regional and individual protected area level. We show that occupancy at the regional level was relatively stable for both species. Much more variation occurred within individual study areas, with some populations declining and some increasing for both species. We found some evidence for a latitudinal gradient in trends among protected areas. However, support for this pattern is overestimated when the hierarchical nature of the data collection is not controlled for in the analysis. For both species, occupancy appeared to be declining in the most southern areas, while occupancy was stable or increasing in more northern areas. These results shed light on the range-level population status of these pond-breeding amphibians and our approach provides a framework that can be used to examine drivers of change including among-year and among-site variation in occurrence dynamics, while properly accounting for nested structure of

Site-occupancy distribution modeling to correct population-trend estimates derived from opportunistic observations

USGS Publications Warehouse

Kery, M.; Royle, J. Andrew; Schmid, Hans; Schaub, M.; Volet, B.; Hafliger, G.; Zbinden, N.

2010-01-01

Species' assessments must frequently be derived from opportunistic observations made by volunteers (i.e., citizen scientists). Interpretation of the resulting data to estimate population trends is plagued with problems, including teasing apart genuine population trends from variations in observation effort. We devised a way to correct for annual variation in effort when estimating trends in occupancy (species distribution) from faunal or floral databases of opportunistic observations. First, for all surveyed sites, detection histories (i.e., strings of detection-nondetection records) are generated. Within-season replicate surveys provide information on the detectability of an occupied site. Detectability directly represents observation effort; hence, estimating detectablity means correcting for observation effort. Second, site-occupancy models are applied directly to the detection-history data set (i.e., without aggregation by site and year) to estimate detectability and species distribution (occupancy, i.e., the true proportion of sites where a species occurs). Site-occupancy models also provide unbiased estimators of components of distributional change (i.e., colonization and extinction rates). We illustrate our method with data from a large citizen-science project in Switzerland in which field ornithologists record opportunistic observations. We analyzed data collected on four species: the widespread Kingfisher (Alcedo atthis. ) and Sparrowhawk (Accipiter nisus. ) and the scarce Rock Thrush (Monticola saxatilis. ) and Wallcreeper (Tichodroma muraria. ). Our method requires that all observed species are recorded. Detectability was <1 and varied over the years. Simulations suggested some robustness, but we advocate recording complete species lists (checklists), rather than recording individual records of single species. The representation of observation effort with its effect on detectability provides a solution to the problem of differences in effort encountered

Occupancy of Norepinephrine Transporter by Duloxetine in Human Brains Measured by Positron Emission Tomography with (S,S)-[18F]FMeNER-D2.

PubMed

Moriguchi, Sho; Takano, Harumasa; Kimura, Yasuyuki; Nagashima, Tomohisa; Takahata, Keisuke; Kubota, Manabu; Kitamura, Soichiro; Ishii, Tatsuya; Ichise, Masanori; Zhang, Ming-Rong; Shimada, Hitoshi; Mimura, Masaru; Meyer, Jeffrey H; Higuchi, Makoto; Suhara, Tetsuya

2017-12-01

The norepinephrine transporter in the brain has been targeted in the treatment of psychiatric disorders. Duloxetine is a serotonin and norepinephrine reuptake inhibitor that has been widely used for the treatment of depression. However, the relationship between dose and plasma concentration of duloxetine and norepinephrine transporter occupancy in the human brain has not been determined. In this study, we examined norepinephrine transporter occupancy by different doses of duloxetine. We calculated norepinephrine transporter occupancies from 2 positron emission tomography scans using (S,S)-[18F]FMeNER-D2 before and after a single oral dose of duloxetine (20 mg, n = 3; 40 mg, n = 3; 60 mg, n =2). Positron emission tomography scans were performed from 120 to 180 minutes after an i.v. bolus injection of (S,S)-[18F]FMeNER-D2. Venous blood samples were taken to measure the plasma concentration of duloxetine just before and after the second positron emission tomography scan. Norepinephrine transporter occupancy by duloxetine was 29.7% at 20 mg, 30.5% at 40 mg, and 40.0% at 60 mg. The estimated dose of duloxetine inducing 50% norepinephrine transporter occupancy was 76.8 mg, and the estimated plasma drug concentration inducing 50% norepinephrine transporter occupancy was 58.0 ng/mL. Norepinephrine transporter occupancy by clinical doses of duloxetine was approximately 30% to 40% in human brain as estimated using positron emission tomography with (S,S)-[18F]FMeNER-D2. © The Author 2017. Published by Oxford University Press on behalf of CINP.

Prevalence and pattern of occupational exposure to whole body vibration in Great Britain: findings from a national survey

PubMed Central

Palmer, K.; Griffin, M.; Bendall, H.; Pannett, B.; Coggon, D.

2000-01-01

OBJECTIVES—To estimate the number of workers in Great Britain with significant occupational exposure to whole body vibration (WBV) and to identify the common sources of exposure and the occupations and industries where such exposures arise.
METHODS—A postal questionnaire was posted to a random community sample of 22 194 men and women of working age. Among other things, the questionnaire asked about exposure to WBV in the past week, including occupational and common non-occupational sources. Responses were assessed by occupation and industry, and national prevalence estimates were derived from census information. Estimates were also made of the average estimated daily personal dose of vibration (eVDV).
RESULTS—From the 12 907 responses it was estimated that 7.2 million men and 1.8 million women in Great Britain are exposed to WBV at work in a 1 week period if the occupational use of cars, vans, buses, trains, and motor cycles is included within the definition of exposure. The eVDV of >374 000 men and 9000 women was estimated to exceed a proposed British Standard action level of 15 ms-1.75. Occupations in which the estimated exposures most often exceeded 15 ms-1.75 included forklift truck and mechanical truck drivers, farm owners and managers, farm workers, and drivers of road goods vehicles. These occupations also contributed the largest estimated numbers of workers in Great Britain with such levels of exposure. The highest estimated median occupational eVDVs were found in forklift truck drivers, drivers of road goods vehicles, bus and coach drivers, and technical and wholesale sales representatives, among whom a greater contribution to total dose was received from occupational exposures than from non-occupational ones; but in many other occupations the reverse applied. The most common sources of occupational exposure to WBV are cars, vans, forklift trucks, lorries, tractors, buses, and loaders.
CONCLUSIONS—Exposure to whole body vibration is

In vivo imaging of serotonin transporter occupancy by means of SPECT and [123I]ADAM in healthy subjects administered different doses of escitalopram or citalopram.

PubMed

Klein, N; Sacher, J; Geiss-Granadia, T; Attarbaschi, T; Mossaheb, N; Lanzenberger, R; Pötzi, C; Holik, A; Spindelegger, C; Asenbaum, S; Dudczak, R; Tauscher, J; Kasper, S

2006-10-01

Escitalopram is a dual serotonin reuptake inhibitor (SSRI) approved for the treatment of depression and anxiety disorders. It is the S-enantiomer of citalopram, and is responsible for the serotonin reuptake activity, and thus for its pharmacological effects. Previous studies pointed out that clinically efficacious doses of other SSRIs produce an occupancy of the serotonin reuptake transporter (SERT) of about 80% or more. The novel radioligand [123I]ADAM and single photon emission computer tomography (SPECT) were used to measure midbrain SERT occupancies for different doses of escitalopram and citalopram. Twenty-five healthy subjects received a single dose of escitalopram [5 mg (n=5), 10 mg (n=5), and 20 mg (n=5)] or citalopram [(10 mg (n=5) and 20 mg (n=5)]. Midbrain SERT binding was measured with [(123)I]ADAM and SPECT on two study days, once without study drug and once 6 h after single dose administration of the study drug. The ratio of midbrain-cerebellum/cerebellum was the outcome measure (V3") for specific binding to SERT in midbrain. Subsequently, SERT occupancy levels were calculated using the untreated baseline level for each subject. An Emax model was used to describe the relationship between S-citalopram concentrations and SERT occupancy values. Additionally, four subjects received placebo to determine test-retest variability. Single doses of 5, 10, or 20 mg escitalopram led to a mean SERT occupancy of 60+/-6, 64+/-6, and 75+/-5%, respectively. SERT occupancies for subjects treated with single doses of 10 and 20 mg citalopram were 65+/-10 and 70+/-6%, respectively. A statistically significant difference was found between SERT occupancies after application of 10 and 20 mg escitalopram, but not for 10 and 20 mg citalopram. There was no statistically significant difference between the SERT occupancies of either 10 mg citalopram or 10 mg escitalopram, or between 20 mg citalopram and 20 mg escitalopram. Emax was slightly higher after administration of

Dose estimation of eye lens for interventional procedures in diagnosis

NASA Astrophysics Data System (ADS)

Liu, Yu-Rong; Huang, Chia-Yu; Hsu, Ching-Han; Hsu, Fang-Yuh

2017-11-01

The International Commission on Radiological Protection (ICRP) recommended that the equivalent dose limit for the lens of the eye be decreased from 150 mSv/y (ICRP, 2007) to 20 mSv/y averaged over five years (ICRP, 2011). How to accurately measure the eye-lens dose has, therefore, been an issue of interest recently. Interventional radiologists are at a higher risk of radiation-induced eye injury, such as cataracts, than all other occupational radiation workers. The main objective of this study is to investigate the relationship between the doses to the eye lenses of interventional radiologists measured by different commercial eye-lens dosimeters. This study measured a reference eye-lens dose, which involved placing thermoluminescent dosimeter (TLD) chips at the surface of the eye of the Rando Phantom, and the TLD chips were covered by a 3-mm-thick tissue-equivalent bolus. Commercial eye-lens dosimeters, such as a headband dosimeter and standard personnel dose badges, were placed at the positions recommended by the manufacturers. The results show that the personnel dose badge is not an appropriate dosimeter for evaluating eye-lens dose. Dose deviations for different dosimeters are discussed and presented in this study.

Estimating site occupancy and detection probability parameters for meso- and large mammals in a coastal eosystem

USGS Publications Warehouse

O'Connell, Allan F.; Talancy, Neil W.; Bailey, Larissa L.; Sauer, John R.; Cook, Robert; Gilbert, Andrew T.

2006-01-01

Large-scale, multispecies monitoring programs are widely used to assess changes in wildlife populations but they often assume constant detectability when documenting species occurrence. This assumption is rarely met in practice because animal populations vary across time and space. As a result, detectability of a species can be influenced by a number of physical, biological, or anthropogenic factors (e.g., weather, seasonality, topography, biological rhythms, sampling methods). To evaluate some of these influences, we estimated site occupancy rates using species-specific detection probabilities for meso- and large terrestrial mammal species on Cape Cod, Massachusetts, USA. We used model selection to assess the influence of different sampling methods and major environmental factors on our ability to detect individual species. Remote cameras detected the most species (9), followed by cubby boxes (7) and hair traps (4) over a 13-month period. Estimated site occupancy rates were similar among sampling methods for most species when detection probabilities exceeded 0.15, but we question estimates obtained from methods with detection probabilities between 0.05 and 0.15, and we consider methods with lower probabilities unacceptable for occupancy estimation and inference. Estimated detection probabilities can be used to accommodate variation in sampling methods, which allows for comparison of monitoring programs using different protocols. Vegetation and seasonality produced species-specific differences in detectability and occupancy, but differences were not consistent within or among species, which suggests that our results should be considered in the context of local habitat features and life history traits for the target species. We believe that site occupancy is a useful state variable and suggest that monitoring programs for mammals using occupancy data consider detectability prior to making inferences about species distributions or population change.

Dynamic N -occupancy models: estimating demographic rates and local abundance from detection-nondetection data

Treesearch

Sam Rossman; Charles B. Yackulic; Sarah P. Saunders; Janice Reid; Ray Davis; Elise F. Zipkin

2016-01-01

Occupancy modeling is a widely used analytical technique for assessing species distributions and range dynamics. However, occupancy analyses frequently ignore variation in abundance of occupied sites, even though site abundances affect many of the parameters being estimated (e.g., extinction, colonization, detection probability). We introduce a new model (“dynamic

Summary of retrospective asbestos and welding fume exposure estimates for a nuclear naval shipyard and their correlation with radiation exposure estimates.

PubMed

Zaebst, D D; Seel, E A; Yiin, J H; Nowlin, S J; Chen, P

2009-07-01

In support of a nested case-control study at a U.S. naval shipyard, the results of the reconstruction of historical exposures were summarized, and an analysis was undertaken to determine the impact of historical exposures to potential chemical confounders. The nested case-control study (N = 4388) primarily assessed the relationship between lung cancer and external ionizing radiation. Chemical confounders considered important were asbestos and welding fume (as iron oxide fume), and the chromium and nickel content of welding fume. Exposures to the potential confounders were estimated by an expert panel based on a set of quantitatively defined categories of exposure. Distributions of the estimated exposures and trends in exposures over time were examined for the study population. Scatter plots and Spearman rank correlation coefficients were used to assess the degree of association between the estimates of exposure to asbestos, welding fume, and ionizing radiation. Correlation coefficients were calculated separately for 0-, 15-, 20-, and 25-year time-lagged cumulative exposures, total radiation dose (which included medical X-ray dose) and occupational radiation dose. Exposed workers' estimated cumulative exposures to asbestos ranged from 0.01 fiber-days/cm(3) to just under 20,000 fiber-days/cm(3), with a median of 29.0 fiber-days/cm(3). Estimated cumulative exposures to welding fume ranged from 0.16 mg-days/m(3) to just over 30,000 mg-days/m(3), with a median of 603 mg-days/m(3). Spearman correlation coefficients between cumulative radiation dose and cumulative asbestos exposures ranged from 0.09 (occupational dose) to 0.47 (total radiation dose), and those between radiation and welding fume from 0.14 to 0.47. The estimates of relative risk for ionizing radiation and lung cancer were unchanged when lowest and highest estimates of asbestos and welding fume were considered. These results suggest a fairly large proportion of study population workers were exposed to

Inference for occupancy and occupancy dynamics

USGS Publications Warehouse

O'Connell, Allan F.; Bailey, Larissa L.; O'Connell, Allan F.; Nichols, James D.; Karanth, K. Ullas

2011-01-01

This chapter deals with the estimation of occupancy as a state variable to assess the status of, and track changes in, species distributions when sampling with camera traps. Much of the recent interest in occupancy estimation and modeling originated from the models developed by MacKenzie et al. (2002, 2003), although similar methods were developed independently (Azuma et al. 1990; Bayley and Petersen 2001; Nichols and Karanth, 2002; Tyre et al. 2003), all of which deal with species occurrence information and imperfect detection. Less than a decade after these publications, the modeling and estimation of species occurrence and occupancy dynamics have increased significantly. Special features of scientific journals have explored innovative uses of detection–nondetection data with occupancy models (Vojta 2005), and an entire volume has synthesized the use and application of occupancy estimation methods (MacKenzie et al. 2006). Reviews of the topical concepts, philosophical considerations, and various sampling designs that can be used for occupancy estimation are now readily available for a range of audiences (MacKenzie and Royle 2005; MacKenzie et al. 2006; Bailey et al. 2007; Royle and Dorazio 2008; Conroy and Carroll 2009; Kendall and White 2009; Hines et al. 2010; Link and Barker 2010). As a result, it would be pointless here to recast all that these publications have so eloquently articulated, but that said, a review of any scientific topic requires sufficient context and relevant background information, especially when relatively new methodologies and techniques such as occupancy estimation and camera traps are involved. This is especially critical in a digital age where new information is published at warp speed, making it increasingly difficult to stay abreast of theoretical advances and research developments.

A rapid assessment method to estimate the distribution of juvenile Chinook Salmon in tributary habitats using eDNA and occupancy estimation

USGS Publications Warehouse

Matter, A.; Falke, Jeffrey A.; López, J. Andres; Savereide, James W.

2018-01-01

Identification and protection of water bodies used by anadromous species are critical in light of increasing threats to fish populations, yet often challenging given budgetary and logistical limitations. Noninvasive, rapid‐assessment, sampling techniques may reduce costs and effort while increasing species detection efficiencies. We used an intrinsic potential (IP) habitat model to identify high‐quality rearing habitats for Chinook Salmon Oncorhynchus tshawytscha and select sites to sample throughout the Chena River basin, Alaska, for juvenile occupancy using an environmental DNA (eDNA) approach. Water samples were collected from 75 tributary sites in 2014 and 2015. The presence of Chinook Salmon DNA in water samples was assessed using a species‐specific quantitative PCR (qPCR) assay. The IP model predicted over 900 stream kilometers in the basin to support high‐quality (IP ≥ 0.75) rearing habitat. Occupancy estimation based on eDNA samples indicated that 80% and 56% of previously unsampled sites classified as high or low IP (IP < 0.75), respectively, were occupied. The probability of detection (p) of Chinook Salmon DNA from three replicate water samples was high (p = 0.76) but varied with drainage area (km2). A power analysis indicated high power to detect proportional changes in occupancy based on parameter values estimated from eDNA occupancy models, although power curves were not symmetrical around zero, indicating greater power to detect positive than negative proportional changes in occupancy. Overall, the combination of IP habitat modeling and occupancy estimation provided a useful, rapid‐assessment method to predict and subsequently quantify the distribution of juvenile salmon in previously unsampled tributary habitats. Additionally, these methods are flexible and can be modified for application to other species and in other locations, which may contribute towards improved population monitoring and management.

Assessment of the benefits and impacts in the U.S. Nuclear Power Industry of hypothesized lower occupational dose limits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, R.L.; Schmitt, J.F.

1995-03-01

The International Commission on Radiological Protection and the National Council on Radiation Protection and Measurements have issued recommendations that would limit occupational exposure of individuals to doses lower than regulatory limits contained in the Nuclear Regulatory Commission`s 10 CFR Part 20, {open_quotes}Standards for Protection Against Radiation{close_quotes}. Because of this situation, there is interest in the potential benefits and impacts that would be associated with movement of the NRC regulatory limits toward the advisory bodies recommendations. The records of occupational worker doses in the U.S. commercial nuclear power industry show that the vast majority of these workers have doses that aremore » significantly below the regulatory limit of 50 mSv (5 rem) per year. Some workers doses do approach the limits, however. This is most common in the case of specially skilled workers, especially those with skills utilized in support of plant outage work. Any consideration of the potential benefits and impacts of hypothesized lower dose limits must address these workers as an important input to the overall assessment. There are also, of course, many other areas in which the benefits and impacts must be evaluated. To prepare to provide valid, constructive input on this matter, the U.S. nuclear power industry is undertaking an assessment, facilitated by the Nuclear Energy Institute (NEI), of the potential benefits and impacts at its facilities associated with hypothesized lower occupational dose limits. Some preliminary results available to date from this assessment are provided.« less

Space radiation dose estimates on the surface of Mars

NASA Technical Reports Server (NTRS)

Simonsen, Lisa C.; Nealy, John E.; Townsend, Lawrence W.; Wilson, John W.

1990-01-01

The Langley cosmic ray transport code and the Langley nucleon transport code (BRYNTRN) are used to quantify the transport and attenuation of galactic cosmic rays (GCR) and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low density and a high density carbon dioxide model of the atmosphere which, in the vertical direction, provides a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose equivalents which would have been incurred from the three large solar flare events of August 1972, November 1960, and February 1956 are also calculated at the surface. Results indicate surface BFO dose equivalents of approximately 2 to 5, 5 to 7, and 8 to 10 rem per event, respectively. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

The Magnitude of Mortality from Ischemic Heart Disease Attributed to Occupational Factors in Korea - Attributable Fraction Estimation Using Meta-analysis.

PubMed

Ha, Jaehyeok; Kim, Soo-Geun; Paek, Domyung; Park, Jungsun

2011-03-01

Ischemic heart disease (IHD) is a major cause of death in Korea and known to result from several occupational factors. This study attempted to estimate the current magnitude of IHD mortality due to occupational factors in Korea. After selecting occupational risk factors by literature investigation, we calculated attributable fractions (AFs) from relative risks and exposure data for each factor. Relative risks were estimated using meta-analysis based on published research. Exposure data were collected from the 2006 Survey of Korean Working Conditions. Finally, we estimated 2006 occupation-related IHD mortality. FOR THE FACTORS CONSIDERED, WE ESTIMATED THE FOLLOWING RELATIVE RISKS: noise 1.06, environmental tobacco smoke 1.19 (men) and 1.22 (women), shift work 1.12, and low job control 1.15 (men) and 1.08 (women). Combined AFs of those factors in the IHD were estimated at 9.29% (0.3-18.51%) in men and 5.78% (-7.05-19.15%) in women. Based on these fractions, Korea's 2006 death toll from occupational IHD between the age of 15 and 69 was calculated at 353 in men (total 3,804) and 72 in women (total 1,246). We estimated occupational IHD mortality of Korea with updated data and more relevant evidence. Despite the efforts to obtain reliable estimates, there were many assumptions and limitations that must be overcome. Future research based on more precise design and reliable evidence is required for more accurate estimates.

Occupational Asthma

MedlinePlus

... The rate of occupational asthma varies within individual industries. Irritants in high doses that induce occupational asthma ... which is found in the petroleum or chemical industries. If you are exposed to any of these ...

A novel approach for estimating ingested dose associated with paracetamol overdose

PubMed Central

Zurlinden, Todd J.; Heard, Kennon

2015-01-01

Aim In cases of paracetamol (acetaminophen, APAP) overdose, an accurate estimate of tissue‐specific paracetamol pharmacokinetics (PK) and ingested dose can offer health care providers important information for the individualized treatment and follow‐up of affected patients. Here a novel methodology is presented to make such estimates using a standard serum paracetamol measurement and a computational framework. Methods The core component of the computational framework was a physiologically‐based pharmacokinetic (PBPK) model developed and evaluated using an extensive set of human PK data. Bayesian inference was used for parameter and dose estimation, allowing the incorporation of inter‐study variability, and facilitating the calculation of uncertainty in model outputs. Results Simulations of paracetamol time course concentrations in the blood were in close agreement with experimental data under a wide range of dosing conditions. Also, predictions of administered dose showed good agreement with a large collection of clinical and emergency setting PK data over a broad dose range. In addition to dose estimation, the platform was applied for the determination of optimal blood sampling times for dose reconstruction and quantitation of the potential role of paracetamol conjugate measurement on dose estimation. Conclusions Current therapies for paracetamol overdose rely on a generic methodology involving the use of a clinical nomogram. By using the computational framework developed in this study, serum sample data, and the individual patient's anthropometric and physiological information, personalized serum and liver pharmacokinetic profiles and dose estimate could be generated to help inform an individualized overdose treatment and follow‐up plan. PMID:26441245

A novel approach for estimating ingested dose associated with paracetamol overdose.

PubMed

Zurlinden, Todd J; Heard, Kennon; Reisfeld, Brad

2016-04-01

In cases of paracetamol (acetaminophen, APAP) overdose, an accurate estimate of tissue-specific paracetamol pharmacokinetics (PK) and ingested dose can offer health care providers important information for the individualized treatment and follow-up of affected patients. Here a novel methodology is presented to make such estimates using a standard serum paracetamol measurement and a computational framework. The core component of the computational framework was a physiologically-based pharmacokinetic (PBPK) model developed and evaluated using an extensive set of human PK data. Bayesian inference was used for parameter and dose estimation, allowing the incorporation of inter-study variability, and facilitating the calculation of uncertainty in model outputs. Simulations of paracetamol time course concentrations in the blood were in close agreement with experimental data under a wide range of dosing conditions. Also, predictions of administered dose showed good agreement with a large collection of clinical and emergency setting PK data over a broad dose range. In addition to dose estimation, the platform was applied for the determination of optimal blood sampling times for dose reconstruction and quantitation of the potential role of paracetamol conjugate measurement on dose estimation. Current therapies for paracetamol overdose rely on a generic methodology involving the use of a clinical nomogram. By using the computational framework developed in this study, serum sample data, and the individual patient's anthropometric and physiological information, personalized serum and liver pharmacokinetic profiles and dose estimate could be generated to help inform an individualized overdose treatment and follow-up plan. © 2015 The British Pharmacological Society.

Estimation of occupancy, breeding success, and predicted abundance of golden eagles (Aquila chrysaetos) in the Diablo Range, California, 2014

USGS Publications Warehouse

Wiens, J. David; Kolar, Patrick S.; Fuller, Mark R.; Hunt, W. Grainger; Hunt, Teresa

2015-01-01

We used a multistate occupancy sampling design to estimate occupancy, breeding success, and abundance of territorial pairs of golden eagles (Aquila chrysaetos) in the Diablo Range, California, in 2014. This method uses the spatial pattern of detections and non-detections over repeated visits to survey sites to estimate probabilities of occupancy and successful reproduction while accounting for imperfect detection of golden eagles and their young during surveys. The estimated probability of detecting territorial pairs of golden eagles and their young was less than 1 and varied with time of the breeding season, as did the probability of correctly classifying a pair’s breeding status. Imperfect detection and breeding classification led to a sizeable difference between the uncorrected, naïve estimate of the proportion of occupied sites where successful reproduction was observed (0.20) and the model-based estimate (0.30). The analysis further indicated a relatively high overall probability of landscape occupancy by pairs of golden eagles (0.67, standard error = 0.06), but that areas with the greatest occupancy and reproductive potential were patchily distributed. We documented a total of 138 territorial pairs of golden eagles during surveys completed in the 2014 breeding season, which represented about one-half of the 280 pairs we estimated to occur in the broader 5,169-square kilometer region sampled. The study results emphasize the importance of accounting for imperfect detection and spatial heterogeneity in studies of site occupancy, breeding success, and abundance of golden eagles.

Estimating thyroid dose in pediatric CT exams from surface dose measurement

NASA Astrophysics Data System (ADS)

Al-Senan, Rani; Mueller, Deborah L.; Hatab, Mustapha R.

2012-07-01

The purpose of this study was to investigate the possibility of estimating pediatric thyroid doses from CT using surface neck doses. Optically stimulated luminescence dosimeters were used to measure the neck surface dose of 25 children ranging in ages between one and three years old. The neck circumference for each child was measured. The relationship between obtained surface doses and thyroid dose was studied using acrylic phantoms of various sizes and with holes of different depths. The ratios of hole-to-surface doses were used to convert patients' surface dose to thyroid dose. ImPACT software was utilized to calculate thyroid dose after applying the appropriate age correction factors. A paired t-test was performed to compare thyroid doses from our approach and ImPACT. The ratio of thyroid to surface dose was found to be 1.1. Thyroid doses ranged from 20 to 80 mGy. Comparison showed no statistical significance (p = 0.18). In addition, the average of surface dose variation along the z-axis in helical scans was studied and found to range between 5% (in 10 cm diameter phantom/24 mm collimation/pitch 1.0) and 8% (in 16 cm diameter phantom/12 mm collimation/pitch 0.7). We conclude that surface dose is an acceptable predictor for pediatric thyroid dose from CT. The uncertainty due to surface dose variability may be reduced if narrower collimation is used with a pitch factor close to 1.0. Also, the results did not show any effect of thyroid depth on the measured dose.

Distribution of boreal toad populations in relation to estimated UV-B dose in Glacier National Park, Montana, USA

USGS Publications Warehouse

Hossack, B.R.; Diamond, S.A.; Corn, P.S.

2006-01-01

A recent increase in ultraviolet B radiation is one hypothesis advanced to explain suspected or documented declines of the boreal toad (Bufo boreas Baird and Girard, 1852) across much of the western USA, where some experiments have shown ambient UV-B can reduce embryo survival. We examined B. boreas occupancy relative to daily UV-B dose at 172 potential breeding sites in Glacier National Park, Montana, to assess whether UV-B limits the distribution of toads. Dose estimates were based on ground-level UV-B data and the effects of elevation, local topographic and vegetative features, and attenuation in the water column. We also examined temporal trends in surface UV-B and spring snowpack to determine whether populations are likely to have experienced increased UV-B exposure in recent decades. We found no support for the hypothesis that UV-B limits the distribution of populations in the park, even when we analyzed high-elevation ponds separately. Instead, toads were more likely to breed in water bodies with higher estimated UV-B doses. The lack of a detectable trend in surface UV-B since 1979, combined with earlier snow melt in the region and increasing forest density at high elevations, suggests B. boreas embryos and larvae likely have not experienced increased UV-B.

Serotonin transporter occupancy by escitalopram and citalopram in the non-human primate brain: a [(11)C]MADAM PET study.

PubMed

Finnema, Sjoerd J; Halldin, Christer; Bang-Andersen, Benny; Bundgaard, Christoffer; Farde, Lars

2015-11-01

A number of serotonin receptor positron emission tomography (PET) radioligands have been shown to be sensitive to changes in extracellular serotonin concentration, in a generalization of the well-known dopamine competition model. High doses of selective serotonin reuptake inhibitors (SSRIs) decrease serotonin receptor availability in monkey brain, consistent with increased serotonin concentrations. However, two recent studies on healthy human subjects, using a single, lower and clinically relevant SSRI dose, showed increased cortical serotonin receptor radioligand binding, suggesting potential decreases in serotonin concentration in projection regions when initiating treatment. The cross-species differential SSRI effect may be partly explained by serotonin transporter (SERT) occupancy in monkey brain being higher than is clinically relevant. We here determine SERT occupancy after single doses of escitalopram or citalopram by conducting PET measurements with [(11)C]MADAM in monkeys. Relationships between dose, plasma concentration and SERT occupancy were estimated by one-site binding analyses. Binding affinity was expressed as dose (ID50) or plasma concentration (K i) where 50 % SERT occupancy was achieved. Estimated ID50 and K i values were 0.020 mg/kg and 9.6 nmol/L for escitalopram and 0.059 mg/kg and 9.7 nmol/L for citalopram, respectively. Obtained K i values are comparable to values reported in humans. Escitalopram or citalopram doses nearly saturated SERT in previous monkey studies which examined serotonin sensitivity of receptor radioligands. PET-measured cross-species differential effects of SSRI on cortical serotonin concentration may thus be related to SSRI dose. Future monkey studies using SSRI doses inducing clinically relevant SERT occupancy may further illuminate the delayed onset of SSRI therapeutic effects.

A Bayesian Model and Stochastic Exposure (Dose) Estimation for Relative Exposure Risk Comparison Involving Asbestos-Containing Dropped Ceiling Panel Installation and Maintenance Tasks.

PubMed

Boelter, Fred W; Xia, Yulin; Persky, Jacob D

2017-09-01

Assessing exposures to hazards in order to characterize risk is at the core of occupational hygiene. Our study examined dropped ceiling systems commonly used in schools and commercial buildings and lay-in ceiling panels that may have contained asbestos prior to the mid to late 1970s. However, most ceiling panels and tiles do not contain asbestos. Since asbestos risk relates to dose, we estimated the distribution of eight-hour TWA concentrations and one-year exposures (a one-year dose equivalent) to asbestos fibers (asbestos f/cc-years) for five groups of workers who may encounter dropped ceilings: specialists, generalists, maintenance workers, nonprofessional do-it-yourself (DIY) persons, and other tradespersons who are bystanders to ceiling work. Concentration data (asbestos f/cc) were obtained through two exposure assessment studies in the field and one chamber study. Bayesian and stochastic models were applied to estimate distributions of eight-hour TWAs and annual exposures (dose). The eight-hour TWAs for all work categories were below current and historic occupational exposure limits (OELs). Exposures to asbestos fibers from dropped ceiling work would be categorized as "highly controlled" for maintenance workers and "well controlled" for remaining work categories, according to the American Industrial Hygiene Association exposure control rating system. Annual exposures (dose) were found to be greatest for specialists, followed by maintenance workers, generalists, bystanders, and DIY. On a comparative basis, modeled dose and thus risk from dropped ceilings for all work categories were orders of magnitude lower than published exposures for other sources of banned friable asbestos-containing building material commonly encountered in construction trades. © 2016 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

Estimating occupancy and abundance using aerial images with imperfect detection

USGS Publications Warehouse

Williams, Perry J.; Hooten, Mevin B.; Womble, Jamie N.; Bower, Michael R.

2017-01-01

Species distribution and abundance are critical population characteristics for efficient management, conservation, and ecological insight. Point process models are a powerful tool for modelling distribution and abundance, and can incorporate many data types, including count data, presence-absence data, and presence-only data. Aerial photographic images are a natural tool for collecting data to fit point process models, but aerial images do not always capture all animals that are present at a site. Methods for estimating detection probability for aerial surveys usually include collecting auxiliary data to estimate the proportion of time animals are available to be detected.We developed an approach for fitting point process models using an N-mixture model framework to estimate detection probability for aerial occupancy and abundance surveys. Our method uses multiple aerial images taken of animals at the same spatial location to provide temporal replication of sample sites. The intersection of the images provide multiple counts of individuals at different times. We examined this approach using both simulated and real data of sea otters (Enhydra lutris kenyoni) in Glacier Bay National Park, southeastern Alaska.Using our proposed methods, we estimated detection probability of sea otters to be 0.76, the same as visual aerial surveys that have been used in the past. Further, simulations demonstrated that our approach is a promising tool for estimating occupancy, abundance, and detection probability from aerial photographic surveys.Our methods can be readily extended to data collected using unmanned aerial vehicles, as technology and regulations permit. The generality of our methods for other aerial surveys depends on how well surveys can be designed to meet the assumptions of N-mixture models.

Evaluation of an artificial intelligence program for estimating occupational exposures.

PubMed

Johnston, Karen L; Phillips, Margaret L; Esmen, Nurtan A; Hall, Thomas A

2005-03-01

Estimation and Assessment of Substance Exposure (EASE) is an artificial intelligence program developed by UK's Health and Safety Executive to assess exposure. EASE computes estimated airborne concentrations based on a substance's vapor pressure and the types of controls in the work area. Though EASE is intended only to make broad predictions of exposure from occupational environments, some occupational hygienists might attempt to use EASE for individual exposure characterizations. This study investigated whether EASE would accurately predict actual sampling results from a chemical manufacturing process. Personal breathing zone time-weighted average (TWA) monitoring data for two volatile organic chemicals--a common solvent (toluene) and a specialty monomer (chloroprene)--present in this manufacturing process were compared to EASE-generated estimates. EASE-estimated concentrations for specific tasks were weighted by task durations reported in the monitoring record to yield TWA estimates from EASE that could be directly compared to the measured TWA data. Two hundred and six chloroprene and toluene full-shift personal samples were selected from eight areas of this manufacturing process. The Spearman correlation between EASE TWA estimates and measured TWA values was 0.55 for chloroprene and 0.44 for toluene, indicating moderate predictive values for both compounds. For toluene, the interquartile range of EASE estimates at least partially overlapped the interquartile range of the measured data distributions in all process areas. The interquartile range of EASE estimates for chloroprene fell above the interquartile range of the measured data distributions in one process area, partially overlapped the third quartile of the measured data in five process areas and fell within the interquartile range in two process areas. EASE is not a substitute for actual exposure monitoring. However, EASE can be used in conditions that cannot otherwise be sampled and in preliminary

Age- and gender-specific estimates of cumulative CT dose over 5 years using real radiation dose tracking data in children.

PubMed

Lee, Eunsol; Goo, Hyun Woo; Lee, Jae-Yeong

2015-08-01

It is necessary to develop a mechanism to estimate and analyze cumulative radiation risks from multiple CT exams in various clinical scenarios in children. To identify major contributors to high cumulative CT dose estimates using actual dose-length product values collected for 5 years in children. Between August 2006 and July 2011 we reviewed 26,937 CT exams in 13,803 children. Among them, we included 931 children (median age 3.5 years, age range 0 days-15 years; M:F = 533:398) who had 5,339 CT exams. Each child underwent at least three CT scans and had accessible radiation dose reports. Dose-length product values were automatically extracted from DICOM files and we used recently updated conversion factors for age, gender, anatomical region and tube voltage to estimate CT radiation dose. We tracked the calculated CT dose estimates to obtain a 5-year cumulative value for each child. The study population was divided into three groups according to the cumulative CT dose estimates: high, ≥30 mSv; moderate, 10-30 mSv; and low, <10 mSv. We reviewed clinical data and CT protocols to identify major contributors to high and moderate cumulative CT dose estimates. Median cumulative CT dose estimate was 5.4 mSv (range 0.5-71.1 mSv), and median number of CT scans was 4 (range 3-36). High cumulative CT dose estimates were most common in children with malignant tumors (57.9%, 11/19). High frequency of CT scans was attributed to high cumulative CT dose estimates in children with ventriculoperitoneal shunt (35 in 1 child) and malignant tumors (range 18-49). Moreover, high-dose CT protocols, such as multiphase abdomen CT (median 4.7 mSv) contributed to high cumulative CT dose estimates even in children with a low number of CT scans. Disease group, number of CT scans, and high-dose CT protocols are major contributors to higher cumulative CT dose estimates in children.

Location Modification Factors for Potential Dose Estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snyder, Sandra F.; Barnett, J. Matthew

2017-01-01

A Department of Energy facility must comply with the National Emission Standard for Hazardous Air Pollutants for radioactive air emissions. The standard is an effective dose of less than 0.1 mSv yr-1 to the maximum public receptor. Additionally, a lower dose level may be assigned to a specific emission point in a State issued permit. A method to efficiently estimate the expected dose for future emissions is described. This method is most appropriately applied to a research facility with several emission points with generally low emission levels of numerous isotopes.

A novel in vivo receptor occupancy methodology for the glucocorticoid receptor: toward an improved understanding of lung pharmacokinetic/pharmacodynamic relationships.

PubMed

Boger, Elin; Ewing, Pär; Eriksson, Ulf G; Fihn, Britt-Marie; Chappell, Michael; Evans, Neil; Fridén, Markus

2015-05-01

Investigation of pharmacokinetic/pharmacodynamic (PK/PD) relationships for inhaled drugs is challenging because of the limited possibilities of measuring tissue exposure and target engagement in the lung. The aim of this study was to develop a methodology for measuring receptor occupancy in vivo in the rat for the glucocorticoid receptor (GR) to allow more informative inhalation PK/PD studies. From AstraZeneca's chemical library of GR binders, compound 1 [N-(2-amino-2-oxo-ethyl)-3-[5-[(1R,2S)-2-(2,2-difluoropropanoylamino)-1-(2,3-dihydro-1,4-benzodioxin-6-yl)propoxy]indazol-1-yl]-N-methyl-benzamide] was identified to have properties that are useful as a tracer for GR in vitro. When given at an appropriate dose (30 nmol/kg) to rats, compound 1 functioned as a tracer in the lung and spleen in vivo using liquid chromatography-tandem mass spectrometry bioanalysis. The methodology was successfully used to show the dose-receptor occupancy relationship measured at 1.5 hours after intravenous administration of fluticasone propionate (20, 150, and 750 nmol/kg) as well as to characterize the time profile for receptor occupancy after a dose of 90 nmol/kg i.v. The dose giving 50% occupancy was estimated as 47 nmol/kg. The methodology is novel in terms of measuring occupancy strictly in vivo and by using an unlabeled tracer. This feature confers key advantages, including occupancy estimation not being influenced by drug particle dissolution or binding/dissociation taking place postmortem. In addition, the tracer may be labeled for use in positron emission tomography imaging, thus enabling occupancy estimation in humans as a translatable biomarker of target engagement. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Dosing of cytotoxic chemotherapy: impact of renal function estimates on dose.

PubMed

Dooley, M J; Poole, S G; Rischin, D

2013-11-01

Oncology clinicians are now routinely provided with an estimated glomerular filtration rate on pathology reports whenever serum creatinine is requested. The utility of using this for the dose determination of renally excreted drugs compared with other existing methods is needed to inform practice. Renal function was determined by [Tc(99m)]DTPA clearance in adult patients presenting for chemotherapy. Renal function was calculated using the 4-variable Modification of Diet in Renal Disease (4v-MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockcroft and Gault (CG), Wright and Martin formulae. Doses for renal excreted cytotoxic drugs, including carboplatin, were calculated. The concordance of the renal function estimates according to the CKD classification with measured Tc(99m)DPTA clearance in 455 adults (median age 64.0 years: range 17-87 years) for the 4v-MDRD, CKD-EPI, CG, Martin and Wright formulae was 47.7%, 56.3%, 46.2%, 56.5% and 60.2%, respectively. Concordance for chemotherapy dose for these formulae was 89.0%, 89.5%, 85.1%, 89.9% and 89.9%, respectively. Concordance for carboplatin dose specifically was 66.4%, 71.4%, 64.0%, 73.8% and 73.2%. All bedside formulae provide similar levels of concordance in dosage selection for the renal excreted chemotherapy drugs when compared with the use of a direct measure of renal function.

32 CFR 218.4 - Dose estimate reporting standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) MISCELLANEOUS GUIDANCE FOR THE DETERMINATION AND REPORTING OF NUCLEAR RADIATION DOSE FOR DOD PARTICIPANTS IN THE ATMOSPHERIC NUCLEAR TEST PROGRAM (1945-1962) § 218.4 Dose estimate reporting standards. The following minimum... of the radiation environment to which the veteran was exposed and shall include inhaled, ingested...

32 CFR 218.4 - Dose estimate reporting standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) MISCELLANEOUS GUIDANCE FOR THE DETERMINATION AND REPORTING OF NUCLEAR RADIATION DOSE FOR DOD PARTICIPANTS IN THE ATMOSPHERIC NUCLEAR TEST PROGRAM (1945-1962) § 218.4 Dose estimate reporting standards. The following minimum... of the radiation environment to which the veteran was exposed and shall include inhaled, ingested...

32 CFR 218.4 - Dose estimate reporting standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) MISCELLANEOUS GUIDANCE FOR THE DETERMINATION AND REPORTING OF NUCLEAR RADIATION DOSE FOR DOD PARTICIPANTS IN THE ATMOSPHERIC NUCLEAR TEST PROGRAM (1945-1962) § 218.4 Dose estimate reporting standards. The following minimum... of the radiation environment to which the veteran was exposed and shall include inhaled, ingested...

32 CFR 218.4 - Dose estimate reporting standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) MISCELLANEOUS GUIDANCE FOR THE DETERMINATION AND REPORTING OF NUCLEAR RADIATION DOSE FOR DOD PARTICIPANTS IN THE ATMOSPHERIC NUCLEAR TEST PROGRAM (1945-1962) § 218.4 Dose estimate reporting standards. The following minimum... of the radiation environment to which the veteran was exposed and shall include inhaled, ingested...

32 CFR 218.4 - Dose estimate reporting standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) MISCELLANEOUS GUIDANCE FOR THE DETERMINATION AND REPORTING OF NUCLEAR RADIATION DOSE FOR DOD PARTICIPANTS IN THE ATMOSPHERIC NUCLEAR TEST PROGRAM (1945-1962) § 218.4 Dose estimate reporting standards. The following minimum... of the radiation environment to which the veteran was exposed and shall include inhaled, ingested...

Occupancy Estimation and Modeling : Inferring Patterns and Dynamics of Species Occurrence

USGS Publications Warehouse

MacKenzie, D.I.; Nichols, J.D.; Royle, J. Andrew; Pollock, K.H.; Bailey, L.L.; Hines, J.E.

2006-01-01

This is the first book to examine the latest methods in analyzing presence/absence data surveys. Using four classes of models (single-species, single-season; single-species, multiple season; multiple-species, single-season; and multiple-species, multiple-season), the authors discuss the practical sampling situation, present a likelihood-based model enabling direct estimation of the occupancy-related parameters while allowing for imperfect detectability, and make recommendations for designing studies using these models. It provides authoritative insights into the latest in estimation modeling; discusses multiple models which lay the groundwork for future study designs; addresses critical issues of imperfect detectibility and its effects on estimation; and explores the role of probability in estimating in detail.

Exposure-Response Estimates for Diesel Engine Exhaust and Lung Cancer Mortality Based on Data from Three Occupational Cohorts

PubMed Central

Silverman, Debra T.; Garshick, Eric; Vlaanderen, Jelle; Portengen, Lützen; Steenland, Kyle

2013-01-01

Background: Diesel engine exhaust (DEE) has recently been classified as a known human carcinogen. Objective: We derived a meta-exposure–response curve (ERC) for DEE and lung cancer mortality and estimated lifetime excess risks (ELRs) of lung cancer mortality based on assumed occupational and environmental exposure scenarios. Methods: We conducted a meta-regression of lung cancer mortality and cumulative exposure to elemental carbon (EC), a proxy measure of DEE, based on relative risk (RR) estimates reported by three large occupational cohort studies (including two studies of workers in the trucking industry and one study of miners). Based on the derived risk function, we calculated ELRs for several lifetime occupational and environmental exposure scenarios and also calculated the fractions of annual lung cancer deaths attributable to DEE. Results: We estimated a lnRR of 0.00098 (95% CI: 0.00055, 0.0014) for lung cancer mortality with each 1-μg/m3-year increase in cumulative EC based on a linear meta-regression model. Corresponding lnRRs for the individual studies ranged from 0.00061 to 0.0012. Estimated numbers of excess lung cancer deaths through 80 years of age for lifetime occupational exposures of 1, 10, and 25 μg/m3 EC were 17, 200, and 689 per 10,000, respectively. For lifetime environmental exposure to 0.8 μg/m3 EC, we estimated 21 excess lung cancer deaths per 10,000. Based on broad assumptions regarding past occupational and environmental exposures, we estimated that approximately 6% of annual lung cancer deaths may be due to DEE exposure. Conclusions: Combined data from three U.S. occupational cohort studies suggest that DEE at levels common in the workplace and in outdoor air appear to pose substantial excess lifetime risks of lung cancer, above the usually acceptable limits in the United States and Europe, which are generally set at 1/1,000 and 1/100,000 based on lifetime exposure for the occupational and general population, respectively. Citation

EXPOSURE RELATED DOSE ESTIMATING MODEL (ERDEM)

EPA Science Inventory

ERDEM is a physiologically-based pharmacokinetic (PBPK) model with a graphical user interface (GUI) front end. Such a mathematical model was needed to make reliable estimates of the chemical dose to organs of animals or humans because of uncertainties of making route-to route, lo...

Dose Estimating Application Software Modification: Additional Function of a Size-Specific Effective Dose Calculator and Auto Exposure Control.

PubMed

Kobayashi, Masanao; Asada, Yasuki; Matsubara, Kosuke; Suzuki, Shouichi; Matsunaga, Yuta; Haba, Tomonobu; Kawaguchi, Ai; Daioku, Tomihiko; Toyama, Hiroshi; Kato, Ryoichi

2017-05-01

Adequate dose management during computed tomography is important. In the present study, the dosimetric application software ImPACT was added to a functional calculator of the size-specific dose estimate and was part of the scan settings for the auto exposure control (AEC) technique. This study aimed to assess the practicality and accuracy of the modified ImPACT software for dose estimation. We compared the conversion factors identified by the software with the values reported by the American Association of Physicists in Medicine Task Group 204, and we noted similar results. Moreover, doses were calculated with the AEC technique and a fixed-tube current of 200 mA for the chest-pelvis region. The modified ImPACT software could estimate each organ dose, which was based on the modulated tube current. The ability to perform beneficial modifications indicates the flexibility of the ImPACT software. The ImPACT software can be further modified for estimation of other doses. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Uncertainties in estimating heart doses from 2D-tangential breast cancer radiotherapy.

PubMed

Lorenzen, Ebbe L; Brink, Carsten; Taylor, Carolyn W; Darby, Sarah C; Ewertz, Marianne

2016-04-01

We evaluated the accuracy of three methods of estimating radiation dose to the heart from two-dimensional tangential radiotherapy for breast cancer, as used in Denmark during 1982-2002. Three tangential radiotherapy regimens were reconstructed using CT-based planning scans for 40 patients with left-sided and 10 with right-sided breast cancer. Setup errors and organ motion were simulated using estimated uncertainties. For left-sided patients, mean heart dose was related to maximum heart distance in the medial field. For left-sided breast cancer, mean heart dose estimated from individual CT-scans varied from <1Gy to >8Gy, and maximum dose from 5 to 50Gy for all three regimens, so that estimates based only on regimen had substantial uncertainty. When maximum heart distance was taken into account, the uncertainty was reduced and was comparable to the uncertainty of estimates based on individual CT-scans. For right-sided breast cancer patients, mean heart dose based on individual CT-scans was always <1Gy and maximum dose always <5Gy for all three regimens. The use of stored individual simulator films provides a method for estimating heart doses in left-tangential radiotherapy for breast cancer that is almost as accurate as estimates based on individual CT-scans. Copyright © 2016. Published by Elsevier Ireland Ltd.

Occupational Exposure to Diesel Motor Exhaust and Lung Cancer: A Dose-Response Relationship Hidden by Asbestos Exposure Adjustment? The ICARE Study

PubMed Central

Matrat, Mireille; Guida, Florence; Cénée, Sylvie; Févotte, Joelle; Carton, Matthieu; Cyr, Diane; Menvielle, Gwenn; Paget-Bailly, Sophie; Radoï, Loredana; Schmaus, Annie; Bara, Simona; Velten, Michel; Luce, Danièle; Stücker, Isabelle; The Icare Study Group

2015-01-01

Background. In a French large population-based case-control study we investigated the dose-response relationship between lung cancer and occupational exposure to diesel motor exhaust (DME), taking into account asbestos exposure. Methods. Exposure to DME was assessed by questionnaire. Asbestos was taken into account through a global indicator of exposure to occupational carcinogens or by a specific JEM. Results. We found a crude dose response relationship with most of the indicators of DME exposure, including with the cumulative exposure index. All results were affected by adjustment for asbestos exposure. The dose response relationships between DME and lung cancer were observed among subjects never exposed to asbestos. Conclusions. Exposure to DME and to asbestos is frequently found among the same subjects, which may explain why dose-response relationships in previous studies that adjusted for asbestos exposure were inconsistent. PMID:26425123

Dose estimates for the 1104 m APS storage ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moe, H.J.

1989-06-01

The estimated dose equivalent rates outside the shielded storage ring, and the estimated annual dose equivalent to members of the public due to direct radiation and skyshine from the ring, have been recalculated. The previous estimates found in LS-84 (MOE 87) and cited in the 1987 Conceptual Design Report of the APS (ANL 87) required revision because of changes in the ring circumference and in the proposed location of the ring with respect to the nearest site boundary. The values assumed for the neutron quality factors were also overestimated (by a factor of 2) in the previous computation, and themore » correct values have been used for this estimate. The methodology used to compute dose and dose rate from the storage ring is the same as that used in LS-90 (MOE 87a). The calculations assumed 80 cm thick walls of ordinary concrete (or the shielding equivalent of this) and a roof thickness of 1 meter of ordinary concrete. The circumference of the ring was increased to 1,104 m, and the closest distance to the boundary was taken as 140 m. The recalculation of the skyshine component used the same methodology as that used in LS-84.« less

CALCULATIONAL TOOL FOR SKIN CONTAMINATION DOSE ESTIMATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

HILL, R.L.

2005-03-31

A spreadsheet calculational tool was developed to automate the calculations performed for estimating dose from skin contamination. This document reports on the design and testing of the spreadsheet calculational tool.

Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Porto, L. E.; Ledesma, J. A.; Nascimento, E. X.; Legnani, A.; Andrade, M. E. A.; Khoury, H. J.

2015-11-01

This study investigates patient and staff dose measurements in pediatric barium meal series fluoroscopic procedures. It aims to analyze radiographic techniques, measure the air kerma-area product (PKA), and estimate the staff's eye lens, thyroid and hands equivalent doses. The procedures of 41 patients were studied, and PKA values were calculated using LiF:Mg,Ti thermoluminescent dosimeters (TLDs) positioned at the center of the patient's upper chest. Furthermore, LiF:Mg,Cu,P TLDs were used to estimate the equivalent doses. The results showed a discrepancy in the radiographic techniques when compared to the European Commission recommendations. Half of the results of the analyzed literature presented lower PKA and dose reference level values than the present study. The staff's equivalent doses strongly depends on the distance from the beam. A 55-cm distance can be considered satisfactory. However, a distance decrease of ~20% leads to, at least, two times higher equivalent doses. For eye lenses this dose is significantly greater than the annual limit set by the International Commission on Radiological Protection. In addition, the occupational doses were found to be much higher than in the literature. Changing the used radiographic techniques to the ones recommended by the European Communities, it is expected to achieve lower PKA values ​​and occupational doses.

Patient-specific dose estimation for pediatric chest CT

PubMed Central

Li, Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P.

2008-01-01

Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9–18.2kg) were created based on the patients’ actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structures were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120kVp, 70 or 75mA, 0.4s gantry rotation period, pitch of 1.375, 20mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7–5.3mSv∕100mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4–12.6mGy∕100mAs and 11.2–13.3mGy∕100mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%–18%) and for partially or indirectly exposed organs (11%–77%). Normalized effective dose correlated weakly with body weight (correlation coefficient:r=−0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=−0.99, heart: r=−0.93); these strong correlation relationships can be used to estimate patient

Patient-specific dose estimation for pediatric chest CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Xiang; Samei, Ehsan; Segars, W. Paul

2008-12-15

Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9-18.2 kg) were created based on the patients' actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structuresmore » were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120 kVp, 70 or 75 mA, 0.4 s gantry rotation period, pitch of 1.375, 20 mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7-5.3 mSv/100 mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4-12.6 mGy/100 mAs and 11.2-13.3 mGy/100 mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%-18%) and for partially or indirectly exposed organs (11%-77%). Normalized effective dose correlated weakly with body weight (correlation coefficient: r=-0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=-0.99, heart: r=-0.93); these strong correlation relationships can be used to estimate patient-specific organ

Current situations and discussions in Japan in relation to the new occupational equivalent dose limit for the lens of the eye.

PubMed

Yokoyama, Sumi; Hamada, Nobuyuki; Hayashida, Toshiyuki; Tsujimura, Norio; Tatsuzaki, Hideo; Kurosawa, Tadahiro; Nabatame, Kuniaki; Ohguchi, Hiroyuki; Ohno, Kazuko; Yamauchi-Kawaura, Chiyo; Iimoto, Takeshi; Ichiji, Takeshi; Hotta, Yutaka; Iwai, Satoshi; Akahane, Keiichi

2017-09-25

Since the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens of the eye in 2011, there have been extensive discussions in various countries. This paper reviews the current situation in radiation protection of the ocular lens and the discussions on the potential impact of the new lens dose limit in Japan. Topics include historical changes to the lens dose limit, the current situation with occupational lens exposures (e.g., in medical workers, nuclear workers, and Fukushima nuclear power plant workers) and measurements, and the current status of biological studies and epidemiological studies on radiation cataracts. Our focus is on the situation in Japan, but we believe such information sharing will be useful in many other countries.

Sampling scales define occupancy and underlying occupancy-abundance relationships in animals.

PubMed

Steenweg, Robin; Hebblewhite, Mark; Whittington, Jesse; Lukacs, Paul; McKelvey, Kevin

2018-01-01

Occupancy-abundance (OA) relationships are a foundational ecological phenomenon and field of study, and occupancy models are increasingly used to track population trends and understand ecological interactions. However, these two fields of ecological inquiry remain largely isolated, despite growing appreciation of the importance of integration. For example, using occupancy models to infer trends in abundance is predicated on positive OA relationships. Many occupancy studies collect data that violate geographical closure assumptions due to the choice of sampling scales and application to mobile organisms, which may change how occupancy and abundance are related. Little research, however, has explored how different occupancy sampling designs affect OA relationships. We develop a conceptual framework for understanding how sampling scales affect the definition of occupancy for mobile organisms, which drives OA relationships. We explore how spatial and temporal sampling scales, and the choice of sampling unit (areal vs. point sampling), affect OA relationships. We develop predictions using simulations, and test them using empirical occupancy data from remote cameras on 11 medium-large mammals. Surprisingly, our simulations demonstrate that when using point sampling, OA relationships are unaffected by spatial sampling grain (i.e., cell size). In contrast, when using areal sampling (e.g., species atlas data), OA relationships are affected by spatial grain. Furthermore, OA relationships are also affected by temporal sampling scales, where the curvature of the OA relationship increases with temporal sampling duration. Our empirical results support these predictions, showing that at any given abundance, the spatial grain of point sampling does not affect occupancy estimates, but longer surveys do increase occupancy estimates. For rare species (low occupancy), estimates of occupancy will quickly increase with longer surveys, even while abundance remains constant. Our results

Internal thyroid doses to Fukushima residents—estimation and issues remaining

PubMed Central

Kim, Eunjoo; Kurihara, Osamu; Kunishima, Naoaki; Momose, Takumaro; Ishikawa, Tetsuo; Akashi, Makoto

2016-01-01

Enormous quantities of radionuclides were released into the environment following the disastrous accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011. It is of great importance to determine the exposure doses received by the populations living in the radiologically affected areas; however, there has been significant difficulty in estimating the internal thyroid dose received through the intake of short-lived radionuclides (mainly, 131I), because of the lack of early measurements on people. An estimation by the National Institute of Radiological Sciences for 1 April 2012 to 31 March 2013 was thus performed using a combination of the following three sources: thyroid measurement data (131I) for 1080 children examined in the screening campaign, whole-body counter measurement data (134Cs, 137Cs) for 3000 adults, and atmospheric transport dispersion model simulations. In this study, the residents of Futaba town, Iitate village and Iwaki city were shown to have the highest thyroid equivalent dose, and their doses were estimated to be mostly below 30 mSv. However, this result involved a lot of uncertainties and provided only representative values for the residents. The present paper outlines a more recent dose estimation and preliminary analyses of personal behavior data used in the new method. PMID:27538842

Simplification of an MCNP model designed for dose rate estimation

NASA Astrophysics Data System (ADS)

Laptev, Alexander; Perry, Robert

2017-09-01

A study was made to investigate the methods of building a simplified MCNP model for radiological dose estimation. The research was done using an example of a complicated glovebox with extra shielding. The paper presents several different calculations for neutron and photon dose evaluations where glovebox elements were consecutively excluded from the MCNP model. The analysis indicated that to obtain a fast and reasonable estimation of dose, the model should be realistic in details that are close to the tally. Other details may be omitted.

An atlas-based organ dose estimator for tomosynthesis and radiography

NASA Astrophysics Data System (ADS)

Hoye, Jocelyn; Zhang, Yakun; Agasthya, Greeshma; Sturgeon, Greg; Kapadia, Anuj; Segars, W. Paul; Samei, Ehsan

2017-03-01

The purpose of this study was to provide patient-specific organ dose estimation based on an atlas of human models for twenty tomosynthesis and radiography protocols. The study utilized a library of 54 adult computational phantoms (age: 18-78 years, weight 52-117 kg) and a validated Monte-Carlo simulation (PENELOPE) of a tomosynthesis and radiography system to estimate organ dose. Positioning of patient anatomy was based on radiographic positioning handbooks. The field of view for each exam was calculated to include relevant organs per protocol. Through simulations, the energy deposited in each organ was binned to estimate normalized organ doses into a reference database. The database can be used as the basis to devise a dose calculator to predict patient-specific organ dose values based on kVp, mAs, exposure in air, and patient habitus for a given protocol. As an example of the utility of this tool, dose to an organ was studied as a function of average patient thickness in the field of view for a given exam and as a function of Body Mass Index (BMI). For tomosynthesis, organ doses can also be studied as a function of x-ray tube position. This work developed comprehensive information for organ dose dependencies across tomosynthesis and radiography. There was a general exponential decrease dependency with increasing patient size that is highly protocol dependent. There was a wide range of variability in organ dose across the patient population, which needs to be incorporated in the metrology of organ dose.

Size-specific dose estimate (SSDE) provides a simple method to calculate organ dose for pediatric CT examinations

PubMed Central

Moore, Bria M.; Brady, Samuel L.; Mirro, Amy E.; Kaufman, Robert A.

2014-01-01

Purpose: To investigate the correlation of size-specific dose estimate (SSDE) with absorbed organ dose, and to develop a simple methodology for estimating patient organ dose in a pediatric population (5–55 kg). Methods: Four physical anthropomorphic phantoms representing a range of pediatric body habitus were scanned with metal oxide semiconductor field effect transistor (MOSFET) dosimeters placed at 23 organ locations to determine absolute organ dose. Phantom absolute organ dose was divided by phantom SSDE to determine correlation between organ dose and SSDE. Organ dose correlation factors (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}${\\rm CF}_{{\\rm SSDE}}^{{\\rm organ}}$\\end{document} CF SSDE organ ) were then multiplied by patient-specific SSDE to estimate patient organ dose. The \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}${\\rm CF}_{{\\rm SSDE}}^{{\\rm organ}}$\\end{document} CF SSDE organ were used to retrospectively estimate individual organ doses from 352 chest and 241 abdominopelvic pediatric CT examinations, where mean patient weight was 22 kg ± 15 (range 5–55 kg), and mean patient age was 6 yrs ± 5 (range 4 months to 23 yrs). Patient organ dose estimates were compared to published pediatric Monte Carlo study results. Results: Phantom effective diameters were matched with patient population effective diameters to within 4 cm; thus, showing appropriate scalability of the phantoms across the entire pediatric population in this study. Individual\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage

Relationship between cocaine-induced subjective effects and dopamine transporter occupancy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Volkow, N.D.; Fischman, M.; Wang, G.J.

The ability of cocaine to occupy the dopamine transporter has been linked to its reinforcing properties. However, such a relationship has not been demonstrated in humans. Methods: Positron Emission Tomography and [C-11]cocaine were used to estimate dopamine transporter occupancies after different doses of cocaine in 18 active cocaine abusers. The ratio of the distribution volume of [C-11]cocaine in striatum to that in cerebellum, which corresponds to Bmax/Kd +1 and is insensitive to changes in cerebral blood flow, was our measure of dopamine transporter availability. In parallel subjective effects were measured to assess the relationship between dopamine transporter occupancy and cocainesmore » behavioral effects. Intravenous cocaine produced a significant dose,-dependent blockade of dopamine transporters: 73 % for 0.6 mg/kg; 601/6 for 0.3 mg/kg; 48 % for 0.1 mg/kg iv and 40 % for 0.05 mg/kg. In addition, dopamine transporter occupancies were significantly correlated with cocaine plasma concentration (r = 0.55 p < 0.001). Cocaine also produced dose-dependent increases in self-reported ratings of {open_quotes}high{close_quotes} which were significantly correlated with the levels of dopamine transporter blockade. Discussion: These results provide the first documentation in humans that dopamine transporter occupancy is associated with cocaine induced subjective effects. They also suggest that dopamine transporter occupancies equal to or greater than 60% are required to produce significant effects on ratings of {open_quotes}high{close_quotes}.« less

Estimating organ doses from tube current modulated CT examinations using a generalized linear model.

PubMed

Bostani, Maryam; McMillan, Kyle; Lu, Peiyun; Kim, Grace Hyun J; Cody, Dianna; Arbique, Gary; Greenberg, S Bruce; DeMarco, John J; Cagnon, Chris H; McNitt-Gray, Michael F

2017-04-01

Currently, available Computed Tomography dose metrics are mostly based on fixed tube current Monte Carlo (MC) simulations and/or physical measurements such as the size specific dose estimate (SSDE). In addition to not being able to account for Tube Current Modulation (TCM), these dose metrics do not represent actual patient dose. The purpose of this study was to generate and evaluate a dose estimation model based on the Generalized Linear Model (GLM), which extends the ability to estimate organ dose from tube current modulated examinations by incorporating regional descriptors of patient size, scanner output, and other scan-specific variables as needed. The collection of a total of 332 patient CT scans at four different institutions was approved by each institution's IRB and used to generate and test organ dose estimation models. The patient population consisted of pediatric and adult patients and included thoracic and abdomen/pelvis scans. The scans were performed on three different CT scanner systems. Manual segmentation of organs, depending on the examined anatomy, was performed on each patient's image series. In addition to the collected images, detailed TCM data were collected for all patients scanned on Siemens CT scanners, while for all GE and Toshiba patients, data representing z-axis-only TCM, extracted from the DICOM header of the images, were used for TCM simulations. A validated MC dosimetry package was used to perform detailed simulation of CT examinations on all 332 patient models to estimate dose to each segmented organ (lungs, breasts, liver, spleen, and kidneys), denoted as reference organ dose values. Approximately 60% of the data were used to train a dose estimation model, while the remaining 40% was used to evaluate performance. Two different methodologies were explored using GLM to generate a dose estimation model: (a) using the conventional exponential relationship between normalized organ dose and size with regional water equivalent diameter

42 CFR 82.27 - How can claimants obtain reviews of their NIOSH dose reconstruction results by NIOSH?

Code of Federal Regulations, 2011 CFR

2011-10-01

... METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER THE ENERGY EMPLOYEES OCCUPATIONAL ILLNESS COMPENSATION... estimated in the completed dose reconstructions; or (2) NIOSH changes a scientific element underlying dose..., the methods employed in the review, and the review findings to the claimant, DOL, and DOE. ...

42 CFR 82.27 - How can claimants obtain reviews of their NIOSH dose reconstruction results by NIOSH?

Code of Federal Regulations, 2014 CFR

2014-10-01

... METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER THE ENERGY EMPLOYEES OCCUPATIONAL ILLNESS COMPENSATION... estimated in the completed dose reconstructions; or (2) NIOSH changes a scientific element underlying dose..., the methods employed in the review, and the review findings to the claimant, DOL, and DOE. ...

42 CFR 82.27 - How can claimants obtain reviews of their NIOSH dose reconstruction results by NIOSH?

Code of Federal Regulations, 2012 CFR

2012-10-01

... METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER THE ENERGY EMPLOYEES OCCUPATIONAL ILLNESS COMPENSATION... estimated in the completed dose reconstructions; or (2) NIOSH changes a scientific element underlying dose..., the methods employed in the review, and the review findings to the claimant, DOL, and DOE. ...

42 CFR 82.27 - How can claimants obtain reviews of their NIOSH dose reconstruction results by NIOSH?

Code of Federal Regulations, 2013 CFR

2013-10-01

... METHODS FOR CONDUCTING DOSE RECONSTRUCTION UNDER THE ENERGY EMPLOYEES OCCUPATIONAL ILLNESS COMPENSATION... estimated in the completed dose reconstructions; or (2) NIOSH changes a scientific element underlying dose..., the methods employed in the review, and the review findings to the claimant, DOL, and DOE. ...

Proof of concept and dose estimation with binary responses under model uncertainty.

PubMed

Klingenberg, B

2009-01-30

This article suggests a unified framework for testing Proof of Concept (PoC) and estimating a target dose for the benefit of a more comprehensive, robust and powerful analysis in phase II or similar clinical trials. From a pre-specified set of candidate models, we choose the ones that best describe the observed dose-response. To decide which models, if any, significantly pick up a dose effect, we construct the permutation distribution of the minimum P-value over the candidate set. This allows us to find critical values and multiplicity adjusted P-values that control the familywise error rate of declaring any spurious effect in the candidate set as significant. Model averaging is then used to estimate a target dose. Popular single or multiple contrast tests for PoC, such as the Cochran-Armitage, Dunnett or Williams tests, are only optimal for specific dose-response shapes and do not provide target dose estimates with confidence limits. A thorough evaluation and comparison of our approach to these tests reveal that its power is as good or better in detecting a dose-response under various shapes with many more additional benefits: It incorporates model uncertainty in PoC decisions and target dose estimation, yields confidence intervals for target dose estimates and extends to more complicated data structures. We illustrate our method with the analysis of a Phase II clinical trial. Copyright (c) 2008 John Wiley & Sons, Ltd.

Estimating Toxicity Pathway Activating Doses for High Throughput Chemical Risk Assessments

EPA Science Inventory

Estimating a Toxicity Pathway Activating Dose (TPAD) from in vitro assays as an analog to a reference dose (RfD) derived from in vivo toxicity tests would facilitate high throughput risk assessments of thousands of data-poor environmental chemicals. Estimating a TPAD requires def...

An integrated data model to estimate spatiotemporal occupancy, abundance, and colonization dynamics

USGS Publications Warehouse

Williams, Perry J.; Hooten, Mevin B.; Womble, Jamie N.; Esslinger, George G.; Bower, Michael R.; Hefley, Trevor J.

2017-01-01

Ecological invasions and colonizations occur dynamically through space and time. Estimating the distribution and abundance of colonizing species is critical for efficient management or conservation. We describe a statistical framework for simultaneously estimating spatiotemporal occupancy and abundance dynamics of a colonizing species. Our method accounts for several issues that are common when modeling spatiotemporal ecological data including multiple levels of detection probability, multiple data sources, and computational limitations that occur when making fine-scale inference over a large spatiotemporal domain. We apply the model to estimate the colonization dynamics of sea otters (Enhydra lutris) in Glacier Bay, in southeastern Alaska.

DOE 2011 occupational radiation exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

2012-12-01

The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2011 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protectionmore » of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. The occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site over the past five years.« less

Single point estimation of phenytoin dosing: a reappraisal.

PubMed

Koup, J R; Gibaldi, M; Godolphin, W

1981-11-01

A previously proposed method for estimation of phenytoin dosing requirement using a single serum sample obtained 24 hours after intravenous loading dose (18 mg/Kg) has been re-evaluated. Using more realistic values for the volume of distribution of phenytoin (0.4 to 1.2 L/Kg), simulations indicate that the proposed method will fail to consistently predict dosage requirements. Additional simulations indicate that two samples obtained during the 24 hour interval following the iv loading dose could be used to more reliably predict phenytoin dose requirement. Because of the nonlinear relationship which exists between phenytoin dose administration rate (RO) and the mean steady state serum concentration (CSS), small errors in prediction of the required RO result in much larger errors in CSS.

Tritium internal dose estimation from measurements with liquid scintillators.

PubMed

Pántya, A; Dálnoki, Á; Imre, A R; Zagyvai, P; Pázmándi, T

2018-07-01

Tritium may exist in several chemical and physical forms in workplaces, common occurrences are in vapor or liquid form (as tritiated water) and in organic form (e.g. thymidine) which can get into the body by inhalation or by ingestion. For internal dose assessment it is usually assumed that urine samples for tritium analysis are obtained after the tritium concentration inside the body has reached equilibrium following intake. Comparison was carried out for two types of vials, two efficiency calculation methods and two available liquid scintillation devices to highlight the errors of the measurements. The results were used for dose estimation with MONDAL-3 software. It has been shown that concerning the accuracy of the final internal dose assessment, the uncertainties of the assumptions used in the dose assessment (for example the date and route of intake, the physical and chemical form) can be more influential than the errors of the measured data. Therefore, the improvement of the experimental accuracy alone is not the proper way to improve the accuracy of the internal dose estimation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Estimating occupancy in large landscapes: evaluation of amphibian monitoring in the greater Yellowstone ecosystem

USGS Publications Warehouse

Gould, William R.; Patla, Debra A.; Daley, Rob; Corn, Paul Stephen; Hossack, Blake R.; Bennetts, Robert E.; Peterson, Charles R.

2012-01-01

Monitoring of natural resources is crucial to ecosystem conservation, and yet it can pose many challenges. Annual surveys for amphibian breeding occupancy were conducted in Yellowstone and Grand Teton National Parks over a 4-year period (2006–2009) at two scales: catchments (portions of watersheds) and individual wetland sites. Catchments were selected in a stratified random sample with habitat quality and ease of access serving as strata. All known wetland sites with suitable habitat were surveyed within selected catchments. Changes in breeding occurrence of tiger salamanders, boreal chorus frogs, and Columbia-spotted frogs were assessed using multi-season occupancy estimation. Numerous a priori models were considered within an information theoretic framework including those with catchment and site-level covariates. Habitat quality was the most important predictor of occupancy. Boreal chorus frogs demonstrated the greatest increase in breeding occupancy at the catchment level. Larger changes for all 3 species were detected at the finer site-level scale. Connectivity of sites explained occupancy rates more than other covariates, and may improve understanding of the dynamic processes occurring among wetlands within this ecosystem. Our results suggest monitoring occupancy at two spatial scales within large study areas is feasible and informative.

Probability Distribution of Dose and Dose-Rate Effectiveness Factor for use in Estimating Risks of Solid Cancers From Exposure to Low-Let Radiation.

PubMed

Kocher, David C; Apostoaei, A Iulian; Hoffman, F Owen; Trabalka, John R

2018-06-01

This paper presents an analysis to develop a subjective state-of-knowledge probability distribution of a dose and dose-rate effectiveness factor for use in estimating risks of solid cancers from exposure to low linear energy transfer radiation (photons or electrons) whenever linear dose responses from acute and chronic exposure are assumed. A dose and dose-rate effectiveness factor represents an assumption that the risk of a solid cancer per Gy at low acute doses or low dose rates of low linear energy transfer radiation, RL, differs from the risk per Gy at higher acute doses, RH; RL is estimated as RH divided by a dose and dose-rate effectiveness factor, where RH is estimated from analyses of dose responses in Japanese atomic-bomb survivors. A probability distribution to represent uncertainty in a dose and dose-rate effectiveness factor for solid cancers was developed from analyses of epidemiologic data on risks of incidence or mortality from all solid cancers as a group or all cancers excluding leukemias, including (1) analyses of possible nonlinearities in dose responses in atomic-bomb survivors, which give estimates of a low-dose effectiveness factor, and (2) comparisons of risks in radiation workers or members of the public from chronic exposure to low linear energy transfer radiation at low dose rates with risks in atomic-bomb survivors, which give estimates of a dose-rate effectiveness factor. Probability distributions of uncertain low-dose effectiveness factors and dose-rate effectiveness factors for solid cancer incidence and mortality were combined using assumptions about the relative weight that should be assigned to each estimate to represent its relevance to estimation of a dose and dose-rate effectiveness factor. The probability distribution of a dose and dose-rate effectiveness factor for solid cancers developed in this study has a median (50th percentile) and 90% subjective confidence interval of 1.3 (0.47, 3.6). The harmonic mean is 1.1, which

Brain Serotonin Transporter Occupancy by Oral Sibutramine Dosed to Steady State: A PET Study Using 11C-DASB in Healthy Humans

PubMed Central

Talbot, Peter S; Bradley, Stefan; Clarke, Cyril P; Babalola, Kola O; Philipp, Andrew W; Brown, Gavin; McMahon, Adam W; Matthews, Julian C

2010-01-01

Sibutramine is a centrally acting monoamine reuptake inhibitor prescribed as an appetite suppressant in the management of obesity. Its effects are mostly attributable to serotonin and norepinephrine transporter (SERT and NET, respectively) inhibition by its potent metabolites mono-desmethylsibutramine (M1) and di-desmethylsibutramine (M2). However, there is a paucity of in vivo data in humans about mechanisms underlying both clinical efficacy and the dose-independent non-response observed in a minority of patients. Twelve healthy male patients (mean age 41 years) completed a double-blind, placebo-controlled, within-subject crossover investigation of brain SERT occupancy by sibutramine 15 mg daily at steady state. Correlations were measured between occupancy and (i) plasma concentrations of sibutramine, M1 and M2; (ii) appetite suppression. 11C-DASB PET scans were performed on the HRRT camera. Binding potentials (BPND) were calculated by the Logan reference tissue (cerebellum) method. SERT occupancy was modest (mean 30±10%), was similar across brain regions, but varied widely across subjects (15–46%). Occupancy was correlated positively (p=0.09) with M2 concentration, but not with sibutramine or M1. No significant appetite suppression was seen at <25% occupancy and greatest suppression was associated with highest occupancy (25–46%). However, several subjects with occupancy (36–39%) in the higher range had no appetite suppression. SERT occupancy by clinical doses of sibutramine is of modest magnitude and may be mediated predominantly by M2 in humans. 5-HT reuptake inhibition may be necessary but is not sufficient for sibutramine's efficacy in humans, supporting preclinical data suggesting that the hypophagic effect requires the co-inhibition of both SERT and NET. PMID:19890256

Radiation dose to physicians’ eye lens during interventional radiology

NASA Astrophysics Data System (ADS)

Bahruddin, N. A.; Hashim, S.; Karim, M. K. A.; Sabarudin, A.; Ang, W. C.; Salehhon, N.; Bakar, K. A.

2016-03-01

The demand of interventional radiology has increased, leading to significant risk of radiation where eye lens dose assessment becomes a major concern. In this study, we investigate physicians' eye lens doses during interventional procedures. Measurement were made using TLD-100 (LiF: Mg, Ti) dosimeters and was recorded in equivalent dose at a depth of 0.07 mm, Hp(0.07). Annual Hp(0.07) and annual effective dose were estimated using workload estimation for a year and Von Boetticher algorithm. Our results showed the mean Hp(0.07) dose of 0.33 mSv and 0.20 mSv for left and right eye lens respectively. The highest estimated annual eye lens dose was 29.33 mSv per year, recorded on left eye lens during fistulogram procedure. Five physicians had exceeded 20 mSv dose limit as recommended by international commission of radiological protection (ICRP). It is suggested that frequent training and education on occupational radiation exposure are necessary to increase knowledge and awareness of the physicians’ thus reducing dose during the interventional procedure.

Occupational Exposure of the Eye Lens in Interventional Procedures: How to Assess and Manage Radiation Dose.

PubMed

Ciraj-Bjelac, Olivera; Carinou, Eleftheria; Ferrari, Paolo; Gingaume, Merce; Merce, Marta Sans; O'Connor, Una

2016-11-01

Occupational exposure from interventional x-ray procedures is one of the areas in which increased eye lens exposure may occur. Accurate dosimetry is an important element to investigate the correlation of observed radiation effects with radiation dose, to verify the compliance with regulatory dose limits, and to optimize radiation protection practice. The objective of this work is to review eye lens dose levels in clinical practice that may occur from the use of ionizing radiation. The use of a dedicated eye lens dosimeter is the recommended methodology; however, in practice it cannot always be easily implemented. Alternatively, the eye lens dose could be assessed from measurements of other dosimetric quantities or other indirect parameters, such as patient dose. The practical implementation of monitoring eye lens doses and the use of adequate protective equipment still remains a challenge. The use of lead glasses with a good fit to the face, appropriate lateral coverage, and/or ceiling-suspended screens is recommended in workplaces with potential high eye lens doses. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Estimated ultraviolet radiation doses in wetlands in six national parks

USGS Publications Warehouse

Diamond, S.A.; Trenham, P.C.; Adams, Michael J.; Hossack, B.R.; Knapp, R.A.; Stark, L.; Bradford, D.; Corn, P.S.; Czarnowski, K.; Brooks, P.D.; Fagre, D.B.; Breen, B.; Dentenbeck, N.E.; Tonnessen, K.

2005-01-01

Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B dose estimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m−2 (range of 3.4–32.1 W-h m−2). The mean dose was lowest in Acadia (13.7 W-h m−2) and highest in Rocky (24.4 W-h m−2). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 μW cm−2 (range 21.4–194.7 μW cm−2) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L−1 over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B on aquatic organisms.

Internal thyroid doses to Fukushima residents-estimation and issues remaining.

PubMed

Kim, Eunjoo; Kurihara, Osamu; Kunishima, Naoaki; Momose, Takumaro; Ishikawa, Tetsuo; Akashi, Makoto

2016-08-01

Enormous quantities of radionuclides were released into the environment following the disastrous accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011. It is of great importance to determine the exposure doses received by the populations living in the radiologically affected areas; however, there has been significant difficulty in estimating the internal thyroid dose received through the intake of short-lived radionuclides (mainly, (131)I), because of the lack of early measurements on people. An estimation by the National Institute of Radiological Sciences for 1 April 2012 to 31 March 2013 was thus performed using a combination of the following three sources: thyroid measurement data ((131)I) for 1080 children examined in the screening campaign, whole-body counter measurement data ((134)Cs, (137)Cs) for 3000 adults, and atmospheric transport dispersion model simulations. In this study, the residents of Futaba town, Iitate village and Iwaki city were shown to have the highest thyroid equivalent dose, and their doses were estimated to be mostly below 30 mSv. However, this result involved a lot of uncertainties and provided only representative values for the residents. The present paper outlines a more recent dose estimation and preliminary analyses of personal behavior data used in the new method. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Occupational radon exposure and lung cancer mortality: estimating intervention effects using the parametric g-formula.

PubMed

Edwards, Jessie K; McGrath, Leah J; Buckley, Jessie P; Schubauer-Berigan, Mary K; Cole, Stephen R; Richardson, David B

2014-11-01

Traditional regression analysis techniques used to estimate associations between occupational radon exposure and lung cancer focus on estimating the effect of cumulative radon exposure on lung cancer. In contrast, public health interventions are typically based on regulating radon concentration rather than workers' cumulative exposure. Estimating the effect of cumulative occupational exposure on lung cancer may be difficult in situations vulnerable to the healthy worker survivor bias. Workers in the Colorado Plateau Uranium Miners cohort (n = 4,134) entered the study between 1950 and 1964 and were followed for lung cancer mortality through 2005. We use the parametric g-formula to compare the observed lung cancer mortality to the potential lung cancer mortality had each of 3 policies to limit monthly radon exposure been in place throughout follow-up. There were 617 lung cancer deaths over 135,275 person-years of follow-up. With no intervention on radon exposure, estimated lung cancer mortality by age 90 was 16%. Lung cancer mortality was reduced for all interventions considered, and larger reductions in lung cancer mortality were seen for interventions with lower monthly radon exposure limits. The most stringent guideline, the Mine Safety and Health Administration standard of 0.33 working-level months, reduced lung cancer mortality from 16% to 10% (risk ratio = 0.67 [95% confidence interval = 0.61 to 0.73]). This work illustrates the utility of the parametric g-formula for estimating the effects of policies regarding occupational exposures, particularly in situations vulnerable to the healthy worker survivor bias.

An integrated data model to estimate spatiotemporal occupancy, abundance, and colonization dynamics.

PubMed

Williams, Perry J; Hooten, Mevin B; Womble, Jamie N; Esslinger, George G; Bower, Michael R; Hefley, Trevor J

2017-02-01

Ecological invasions and colonizations occur dynamically through space and time. Estimating the distribution and abundance of colonizing species is critical for efficient management or conservation. We describe a statistical framework for simultaneously estimating spatiotemporal occupancy and abundance dynamics of a colonizing species. Our method accounts for several issues that are common when modeling spatiotemporal ecological data including multiple levels of detection probability, multiple data sources, and computational limitations that occur when making fine-scale inference over a large spatiotemporal domain. We apply the model to estimate the colonization dynamics of sea otters (Enhydra lutris) in Glacier Bay, in southeastern Alaska. © 2016 by the Ecological Society of America.

Estimating Radiation Dose Metrics for Patients Undergoing Tube Current Modulation CT Scans

NASA Astrophysics Data System (ADS)

McMillan, Kyle Lorin

Computed tomography (CT) has long been a powerful tool in the diagnosis of disease, identification of tumors and guidance of interventional procedures. With CT examinations comes the concern of radiation exposure and the associated risks. In order to properly understand those risks on a patient-specific level, organ dose must be quantified for each CT scan. Some of the most widely used organ dose estimates are derived from fixed tube current (FTC) scans of a standard sized idealized patient model. However, in current clinical practice, patient size varies from neonates weighing just a few kg to morbidly obese patients weighing over 200 kg, and nearly all CT exams are performed with tube current modulation (TCM), a scanning technique that adjusts scanner output according to changes in patient attenuation. Methods to account for TCM in CT organ dose estimates have been previously demonstrated, but these methods are limited in scope and/or restricted to idealized TCM profiles that are not based on physical observations and not scanner specific (e.g. don't account for tube limits, scanner-specific effects, etc.). The goal of this work was to develop methods to estimate organ doses to patients undergoing CT scans that take into account both the patient size as well as the effects of TCM. This work started with the development and validation of methods to estimate scanner-specific TCM schemes for any voxelized patient model. An approach was developed to generate estimated TCM schemes that match actual TCM schemes that would have been acquired on the scanner for any patient model. Using this approach, TCM schemes were then generated for a variety of body CT protocols for a set of reference voxelized phantoms for which TCM information does not currently exist. These are whole body patient models representing a variety of sizes, ages and genders that have all radiosensitive organs identified. TCM schemes for these models facilitated Monte Carlo-based estimates of fully

TU-H-207A-08: Estimating Radiation Dose From Low-Dose Lung Cancer Screening CT Exams Using Tube Current Modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardy, A; Bostani, M; McMillan, K

Purpose: The purpose of this work is to estimate effective and lung doses from a low-dose lung cancer screening CT protocol using Tube Current Modulation (TCM) across patient models of different sizes. Methods: Monte Carlo simulation methods were used to estimate effective and lung doses from a low-dose lung cancer screening protocol for a 64-slice CT (Sensation 64, Siemens Healthcare) that used TCM. Scanning parameters were from the AAPM protocols. Ten GSF voxelized patient models were used and had all radiosensitive organs identified to facilitate estimating both organ and effective doses. Predicted TCM schemes for each patient model were generatedmore » using a validated method wherein tissue attenuation characteristics and scanner limitations were used to determine the TCM output as a function of table position and source angle. The water equivalent diameter (WED) was determined by estimating the attenuation at the center of the scan volume for each patient model. Monte Carlo simulations were performed using the unique TCM scheme for each patient model. Lung doses were tallied and effective doses were estimated using ICRP 103 tissue weighting factors. Effective and lung dose values were normalized by scanspecific 32 cm CTDIvol values based upon the average tube current across the entire simulated scan. Absolute and normalized doses were reported as a function of WED for each patient. Results: For all ten patients modeled, the effective dose using TCM protocols was below 1.5 mSv. Smaller sized patient models experienced lower absolute doses compared to larger sized patients. Normalized effective and lung doses showed some dependence on patient size (R2 = 0.77 and 0.78, respectively). Conclusion: Effective doses for a low-dose lung screening protocol using TCM were below 1.5 mSv for all patient models used in this study. Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America

Assessment of occupational cosmic radiation exposure of flight attendants using questionnaire data.

PubMed

Anderson, Jeri L; Waters, Martha A; Hein, Misty J; Schubauer-Berigan, Mary K; Pinkerton, Lynne E

2011-11-01

Female flight attendants may have a higher risk of breast and other cancers than the general population because of routine exposure to cosmic radiation. As part of a forthcoming study of breast and other cancer incidence, occupational cosmic radiation exposure of a cohort of female flight attendants was estimated. Questionnaire data were collected from living female cohort members who were formerly employed as flight attendants with Pan American World Airways. These data included airline at which the flight attendant was employed, assigned domicile, start and end dates for employment at domicile, and number of block hours and commuter segments flown per month. Questionnaire respondents were assigned daily absorbed and effective doses using a time-weighted dose rate specific to the domicile and/or work history era combined with self-reported work history information. Completed work history questionnaires were received from 5898 living cohort members. Mean employment time as a flight attendant was 7.4 yr at Pan Am and 12 yr in total. Estimated mean annual effective dose from all sources of occupational cosmic radiation exposure was 2.5 +/- 1.0 mSv, with a mean career dose of 30 mSv. Annual effective doses were similar to doses assessed for other flight attendant cohorts; however, questionnaire-based cumulative doses assessed in this study were on average higher than those assessed for other flight attendant cohorts using company-based records. The difference is attributed to the inclusion of dose from work at other airlines and commuter flights, which was made possible by using questionnaire data.

Connecting the Dots: Linking Environmental Justice Indicators to Daily Dose Model Estimates

EPA Science Inventory

Many different quantitative techniques have been developed to either assess Environmental Justice (EJ) issues or estimate exposure and dose for risk assessment. However, very few approaches have been applied to link EJ factors to exposure dose estimate and identify potential impa...

SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geneser, S; Paulsson, A; Sneed, P

Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to themore » thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low.« less

Occupational radiation dose to eyes from interventional radiology procedures in light of the new eye lens dose limit from the International Commission on Radiological Protection

PubMed Central

Walsh, C; Gallagher, A; Dowling, A; Guiney, M; Ryan, J M; McEniff, N; O'Reilly, G

2015-01-01

Objective: In 2011, the International Commission on Radiological Protection (ICRP) recommended a substantial reduction in the equivalent dose limit for the lens of the eye, in line with a reduced threshold of absorbed dose for radiation-induced cataracts. This is of particular relevance in interventional radiology (IR) where it is well established that staff doses can be significant, however, there is a lack of data on IR eye doses in terms of Hp(3). Hp(3) is the personal dose equivalent at a depth of 3 mm in soft tissue and is used for measuring lens dose. We aimed to obtain a reliable estimate of eye dose to IR operators. Methods: Lens doses were measured for four interventional radiologists over a 3-month period using dosemeters specifically designed to measure Hp(3). Results: Based on their typical workloads, two of the four interventional radiologists would exceed the new ICRP dose limit with annual estimated doses of 31 and 45 mSv to their left eye. These results are for an “unprotected” eye, and for IR staff who routinely wear lead glasses, the dose beneath the glasses is likely to be significantly lower. Staff eye dose normalized to patient kerma–area product and eye dose per procedure have been included in the analysis. Conclusion: Eye doses to IR operators have been established using a dedicated Hp(3) dosemeter. Estimated annual doses have the potential to exceed the new ICRP limit. Advances in knowledge: We have estimated lens dose to interventional radiologists in terms of Hp(3) for the first time in an Irish hospital setting. PMID:25761211

Estimating open population site occupancy from presence-absence data lacking the robust design.

PubMed

Dail, D; Madsen, L

2013-03-01

Many animal monitoring studies seek to estimate the proportion of a study area occupied by a target population. The study area is divided into spatially distinct sites where the detected presence or absence of the population is recorded, and this is repeated in time for multiple seasons. However, when occupied sites are detected with probability p < 1, the lack of a detection does not imply lack of occupancy. MacKenzie et al. (2003, Ecology 84, 2200-2207) developed a multiseason model for estimating seasonal site occupancy (ψt ) while accounting for unknown p. Their model performs well when observations are collected according to the robust design, where multiple sampling occasions occur during each season; the repeated sampling aids in the estimation p. However, their model does not perform as well when the robust design is lacking. In this paper, we propose an alternative likelihood model that yields improved seasonal estimates of p and Ψt in the absence of the robust design. We construct the marginal likelihood of the observed data by conditioning on, and summing out, the latent number of occupied sites during each season. A simulation study shows that in cases without the robust design, the proposed model estimates p with less bias than the MacKenzie et al. model and hence improves the estimates of Ψt . We apply both models to a data set consisting of repeated presence-absence observations of American robins (Turdus migratorius) with yearly survey periods. The two models are compared to a third estimator available when the repeated counts (from the same study) are considered, with the proposed model yielding estimates of Ψt closest to estimates from the point count model. Copyright © 2013, The International Biometric Society.

Estimation Of Organ Doses From Solar Particle Events For Future Space Exploration Missions

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee; Cucinotta, Francis A.

2006-01-01

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major organ sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of the effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. If sufficient protection is not provided near solar maximum, the radiation risk can be significant due to exposure to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR) on future exploratory-class and long-duration missions. For accurate estimates of overall fatal cancer risks from SPEs, the specific doses at various blood forming organs (BFOs) were considered, because proton fluences and doses vary considerably across marrow regions. Previous estimates of BFO doses from SPEs have used an average body-shielding distribution for the bone marrow based on the computerized anatomical man model (CAM). With the development of an 82-point body-shielding distribution at BFOs, the mean and variance of SPE doses in the major active marrow regions (head and neck, chest, abdomen, pelvis and thighs) will be presented. Consideration of the detailed distribution of bone marrow sites is one of many requirements to improve the estimation of effective doses for radiation cancer risks.

New Fetal Dose Estimates from 18F-FDG Administered During Pregnancy: Standardization of Dose Calculations and Estimations with Voxel-Based Anthropomorphic Phantoms.

PubMed

Zanotti-Fregonara, Paolo; Chastan, Mathieu; Edet-Sanson, Agathe; Ekmekcioglu, Ozgul; Erdogan, Ezgi Basak; Hapdey, Sebastien; Hindie, Elif; Stabin, Michael G

2016-11-01

Data from the literature show that the fetal absorbed dose from 18 F-FDG administration to the pregnant mother ranges from 0.5E-2 to 4E-2 mGy/MBq. These figures were, however, obtained using different quantification techniques and with basic geometric anthropomorphic phantoms. The aim of this study was to refine the fetal dose estimates of published as well as new cases using realistic voxel-based phantoms. The 18 F-FDG doses to the fetus (n = 19; 5-34 wk of pregnancy) were calculated with new voxel-based anthropomorphic phantoms of the pregnant woman. The image-derived fetal time-integrated activity values were combined with those of the mothers' organs from the International Commission on Radiological Protection publication 106 and the dynamic bladder model with a 1-h bladder-voiding interval. The dose to the uterus was used as a proxy for early pregnancy (up to 10 wk). The time-integrated activities were entered into OLINDA/EXM 1.1 to derive the dose with the classic anthropomorphic phantoms of pregnant women, then into OLINDA/EXM 2.0 to assess the dose using new voxel-based phantoms. The average fetal doses (mGy/MBq) with OLINDA/EXM 2.0 were 2.5E-02 in early pregnancy, 1.3E-02 in the late part of the first trimester, 8.5E-03 in the second trimester, and 5.1E-03 in the third trimester. The differences compared with the doses calculated with OLINDA/EXM 1.1 were +7%, +70%, +35%, and -8%, respectively. Except in late pregnancy, the doses estimated with realistic voxelwise anthropomorphic phantoms are higher than the doses derived from old geometric phantoms. The doses remain, however, well below the threshold for any deterministic effects. Thus, pregnancy is not an absolute contraindication of a clinically justified 18 F-FDG PET scan. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America

USGS Publications Warehouse

Chestnut, Tara E.; Anderson, Chauncey; Popa, Radu; Blaustein, Andrew R.; Voytek, Mary; Olson, Deanna H.; Kirshtein, Julie

2014-01-01

Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. Occupancy models have been used to investigate diseases where the focus was on pathogen occurrence in the host. We applied occupancy models to investigate free-living Bd in North American surface waters to determine Bd seasonality, relationships between Bd site occupancy and habitat attributes, and probability of detection from water samples as a function of the number of samples, sample volume, and water quality. We also report on the temporal patterns of Bd density from a 4-year case study of a Bd-positive wetland. We provide evidence that Bd occurs in the environment year-round. Bd exhibited temporal and spatial heterogeneity in density, but did not exhibit seasonality in occupancy. Bd was detected in all months, typically at less than 100 zoospores L−1. The highest density observed was ∼3 million zoospores L−1. We detected Bd in 47% of sites sampled, but estimated that Bd occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When Bd was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure

Uncertainties in estimating health risks associated with exposure to ionising radiation.

PubMed

Preston, R Julian; Boice, John D; Brill, A Bertrand; Chakraborty, Ranajit; Conolly, Rory; Hoffman, F Owen; Hornung, Richard W; Kocher, David C; Land, Charles E; Shore, Roy E; Woloschak, Gayle E

2013-09-01

-rate occupational and perhaps environmental exposures and for exposures to x rays and high-LET radiations used in medicine. The development of models for more reliably combining the epidemiology data with experimental laboratory animal and cellular data can enhance the overall risk assessment approach by providing biologically refined data to strengthen the estimation of effects at low doses as opposed to the sole use of mathematical models of epidemiological data that are primarily driven by medium/high doses. NASA's approach to radiation protection for astronauts, although a unique occupational group, indicates the possible applicability of estimates of risk and their uncertainty in a broader context for developing recommendations on: (1) dose limits for occupational exposure and exposure of members of the public; (2) criteria to limit exposures of workers and members of the public to radon and its short-lived decay products; and (3) the dosimetric quantity (effective dose) used in radiation protection.

Patient-specific dose estimation for pediatric abdomen-pelvis CT

NASA Astrophysics Data System (ADS)

Li, Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P.

2009-02-01

The purpose of this study is to develop a method for estimating patient-specific dose from abdomen-pelvis CT examinations and to investigate dose variation across patients in the same weight group. Our study consisted of seven pediatric patients in the same weight/protocol group, for whom full-body computer models were previously created based on the patients' CT data obtained for clinical indications. Organ and effective dose of these patients from an abdomen-pelvis scan protocol (LightSpeed VCT scanner, 120-kVp, 85-90 mA, 0.4-s gantry rotation period, 1.375-pitch, 40-mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated for the same CT system. The seven patients had effective dose of 2.4-2.8 mSv, corresponding to normalized effective dose of 6.6-8.3 mSv/100mAs (coefficient of variation: 7.6%). Dose variations across the patients were small for large organs in the scan coverage (mean: 6.6%; range: 4.9%-9.2%), larger for small organs in the scan coverage (mean: 10.3%; range: 1.4%-15.6%), and the largest for organs partially or completely outside the scan coverage (mean: 14.8%; range: 5.7%-27.7%). Normalized effective dose correlated strongly with body weight (correlation coefficient: r = -0.94). Normalized dose to the kidney and the adrenal gland correlated strongly with mid-liver equivalent diameter (kidney: r = -0.97; adrenal glands: r = -0.98). Normalized dose to the small intestine correlated strongly with mid-intestine equivalent diameter (r = -0.97). These strong correlations suggest that patient-specific dose may be estimated for any other child in the same size group who undergoes the abdomen-pelvis scan.

NEUROTOXIC EFFECTS OF ENVIRONMENTAL AGENTS: DATA GAPS THAT CHALLENGE DOSE-RESPONSE ESTIMATION

EPA Science Inventory

Neurotoxic effects of environmental agents: Data gaps that challenge dose-response estimation
S Gutter*, P Mendola+, SG Selevan**, D Rice** (*UNC Chapel Hill; +US EPA, NHEERL; **US EPA, NCEA)

Dose-response estimation is a critical feature of risk assessment. It can be...

The Fukushima Health Management Survey: estimation of external doses to residents in Fukushima Prefecture

NASA Astrophysics Data System (ADS)

Ishikawa, Tetsuo; Yasumura, Seiji; Ozasa, Kotaro; Kobashi, Gen; Yasuda, Hiroshi; Miyazaki, Makoto; Akahane, Keiichi; Yonai, Shunsuke; Ohtsuru, Akira; Sakai, Akira; Sakata, Ritsu; Kamiya, Kenji; Abe, Masafumi

2015-08-01

The Fukushima Health Management Survey (including the Basic Survey for external dose estimation and four detailed surveys) was launched after the Fukushima Dai-ichi Nuclear Power Plant accident. The Basic Survey consists of a questionnaire that asks Fukushima Prefecture residents about their behavior in the first four months after the accident; and responses to the questionnaire have been returned from many residents. The individual external doses are estimated by using digitized behavior data and a computer program that included daily gamma ray dose rate maps drawn after the accident. The individual external doses of 421,394 residents for the first four months (excluding radiation workers) had a distribution as follows: 62.0%, <1 mSv 94.0%, <2 mSv 99.4%, <3 mSv. The arithmetic mean and maximum for the individual external doses were 0.8 and 25 mSv, respectively. While most dose estimation studies were based on typical scenarios of evacuation and time spent inside/outside, the Basic Survey estimated doses considering individually different personal behaviors. Thus, doses for some individuals who did not follow typical scenarios could be revealed. Even considering such extreme cases, the estimated external doses were generally low and no discernible increased incidence of radiation-related health effects is expected.

The Fukushima Health Management Survey: estimation of external doses to residents in Fukushima Prefecture

PubMed Central

Ishikawa, Tetsuo; Yasumura, Seiji; Ozasa, Kotaro; Kobashi, Gen; Yasuda, Hiroshi; Miyazaki, Makoto; Akahane, Keiichi; Yonai, Shunsuke; Ohtsuru, Akira; Sakai, Akira; Sakata, Ritsu; Kamiya, Kenji; Abe, Masafumi

2015-01-01

The Fukushima Health Management Survey (including the Basic Survey for external dose estimation and four detailed surveys) was launched after the Fukushima Dai-ichi Nuclear Power Plant accident. The Basic Survey consists of a questionnaire that asks Fukushima Prefecture residents about their behavior in the first four months after the accident; and responses to the questionnaire have been returned from many residents. The individual external doses are estimated by using digitized behavior data and a computer program that included daily gamma ray dose rate maps drawn after the accident. The individual external doses of 421,394 residents for the first four months (excluding radiation workers) had a distribution as follows: 62.0%, <1 mSv; 94.0%, <2 mSv; 99.4%, <3 mSv. The arithmetic mean and maximum for the individual external doses were 0.8 and 25 mSv, respectively. While most dose estimation studies were based on typical scenarios of evacuation and time spent inside/outside, the Basic Survey estimated doses considering individually different personal behaviors. Thus, doses for some individuals who did not follow typical scenarios could be revealed. Even considering such extreme cases, the estimated external doses were generally low and no discernible increased incidence of radiation-related health effects is expected. PMID:26239643

Accuracy of patient-specific organ dose estimates obtained using an automated image segmentation algorithm.

PubMed

Schmidt, Taly Gilat; Wang, Adam S; Coradi, Thomas; Haas, Benjamin; Star-Lack, Josh

2016-10-01

The overall goal of this work is to develop a rapid, accurate, and automated software tool to estimate patient-specific organ doses from computed tomography (CT) scans using simulations to generate dose maps combined with automated segmentation algorithms. This work quantified the accuracy of organ dose estimates obtained by an automated segmentation algorithm. We hypothesized that the autosegmentation algorithm is sufficiently accurate to provide organ dose estimates, since small errors delineating organ boundaries will have minimal effect when computing mean organ dose. A leave-one-out validation study of the automated algorithm was performed with 20 head-neck CT scans expertly segmented into nine regions. Mean organ doses of the automatically and expertly segmented regions were computed from Monte Carlo-generated dose maps and compared. The automated segmentation algorithm estimated the mean organ dose to be within 10% of the expert segmentation for regions other than the spinal canal, with the median error for each organ region below 2%. In the spinal canal region, the median error was [Formula: see text], with a maximum absolute error of 28% for the single-atlas approach and 11% for the multiatlas approach. The results demonstrate that the automated segmentation algorithm can provide accurate organ dose estimates despite some segmentation errors.

Accuracy of patient-specific organ dose estimates obtained using an automated image segmentation algorithm

PubMed Central

Schmidt, Taly Gilat; Wang, Adam S.; Coradi, Thomas; Haas, Benjamin; Star-Lack, Josh

2016-01-01

Abstract. The overall goal of this work is to develop a rapid, accurate, and automated software tool to estimate patient-specific organ doses from computed tomography (CT) scans using simulations to generate dose maps combined with automated segmentation algorithms. This work quantified the accuracy of organ dose estimates obtained by an automated segmentation algorithm. We hypothesized that the autosegmentation algorithm is sufficiently accurate to provide organ dose estimates, since small errors delineating organ boundaries will have minimal effect when computing mean organ dose. A leave-one-out validation study of the automated algorithm was performed with 20 head-neck CT scans expertly segmented into nine regions. Mean organ doses of the automatically and expertly segmented regions were computed from Monte Carlo-generated dose maps and compared. The automated segmentation algorithm estimated the mean organ dose to be within 10% of the expert segmentation for regions other than the spinal canal, with the median error for each organ region below 2%. In the spinal canal region, the median error was −7%, with a maximum absolute error of 28% for the single-atlas approach and 11% for the multiatlas approach. The results demonstrate that the automated segmentation algorithm can provide accurate organ dose estimates despite some segmentation errors. PMID:27921070

Establishing the value of occupational health nurses' contributions to worker health and safety: a pilot test of a user-friendly estimation tool.

PubMed

Graeve, Catherine; McGovern, Patricia; Nachreiner, Nancy M; Ayers, Lynn

2014-01-01

Occupational health nurses use their knowledge and skills to improve the health and safety of the working population; however, companies increasingly face budget constraints and may eliminate health and safety programs. Occupational health nurses must be prepared to document their services and outcomes, and use quantitative tools to demonstrate their value to employers. The aim of this project was to create and pilot test a quantitative tool for occupational health nurses to track their activities and potential cost savings for on-site occupational health nursing services. Tool developments included a pilot test in which semi-structured interviews with occupational health and safety leaders were conducted to identify currents issues and products used for estimating the value of occupational health nursing services. The outcome was the creation of a tool that estimates the economic value of occupational health nursing services. The feasibility and potential value of this tool is described.

Fetus dose estimation in thyroid cancer post-surgical radioiodine therapy.

PubMed

Mianji, Fereidoun A; Diba, Jila Karimi; Babakhani, Asad

2015-01-01

Unrecognised pregnancy during radioisotope therapy of thyroid cancer results in hardly definable embryo/fetus exposures, particularly when the thyroid gland is already removed. Sources of such difficulty include uncertainty in data like pregnancy commencing time, amount and distribution of metastasized thyroid cells in body, effect of the thyroidectomy on the fetus dose coefficient etc. Despite all these uncertainties, estimation of the order of the fetus dose in most cases is enough for medical and legal decision-making purposes. A model for adapting the dose coefficients recommended by the well-known methods to the problem of fetus dose assessment in athyrotic patients is proposed. The model defines a correction factor for the problem and ensures that the fetus dose in athyrotic pregnant patients is less than the normal patients. A case of pregnant patient undergone post-surgical therapy by I-131 is then studied for quantitative comparison of the methods. The results draw a range for the fetus dose in athyrotic patients using the derived factor. This reduces the concerns on under- or over-estimation of the embryo/fetus dose and is helpful for personal and/or legal decision-making on abortion. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dose-Related Target Occupancy and Effects on Circuitry, Behavior, and Neuroplasticity of the Glycine Transporter-1 Inhibitor PF-03463275 in Healthy and Schizophrenia Subjects.

PubMed

D'Souza, Deepak Cyril; Carson, Richard E; Driesen, Naomi; Johannesen, Jason; Ranganathan, Mohini; Krystal, John H

2018-01-31

Glycine transporter-1 (GlyT1) inhibitors may ameliorate cognitive impairments associated with schizophrenia. The dose-related occupancy and target engagement of the GlyT1 inhibitor PF-03463275 were studied to inform optimal dose selection for a clinical trial for cognitive impairments associated with schizophrenia. In substudy 1, the effects of PF-03463275 (10, 20, and 40 mg twice a day) on occupancy of GlyT1 were tested using positron emission tomography and 18 F-MK-6577, and visual long-term potentiation (LTP) in schizophrenia patients (SZs) and healthy control subjects. Furthermore, the capacity of PF-03463275 to attenuate ketamine-induced disruption of working memory-related activation of a "working memory" circuit was tested only in healthy control subjects using functional magnetic resonance imaging. Subsequently, the effects of PF-03463275 (60 mg twice a day) on occupancy of GlyT1 and long-term potentiation were examined only in SZs (substudy 2). PF-03463275 at 10, 20, 40, and 60 mg twice a day produced ∼44%, 61%, 76%, and 83% GlyT1 occupancy, respectively, in SZs with higher ligand binding to GlyT1 in subcortical versus cortical regions. PF-03463275 did not attenuate any ketamine-induced effects but did improve working memory accuracy in healthy control subjects. PF-03463275 increased long-term potentiation only in SZs with peak effects at 40 mg twice a day (∼75% GlyT1 occupancy) and with a profile suggestive of an inverted U dose response. PF-03463275 was well-tolerated. The dose-related GlyT1 occupancy of PF-03463275 is linear. While PF-03463275 did not show evidence of facilitating N-methyl-D-aspartate receptor function in the ketamine assay, it enhanced neuroplasticity in SZs. These findings provide support for a clinical trial to test the ability of PF-03463275 to enhance cognitive remediation toward addressing cognitive impairments associated with schizophrenia. Published by Elsevier Inc.

Pediatric chest and abdominopelvic CT: organ dose estimation based on 42 patient models.

PubMed

Tian, Xiaoyu; Li, Xiang; Segars, W Paul; Paulson, Erik K; Frush, Donald P; Samei, Ehsan

2014-02-01

To estimate organ dose from pediatric chest and abdominopelvic computed tomography (CT) examinations and evaluate the dependency of organ dose coefficients on patient size and CT scanner models. The institutional review board approved this HIPAA-compliant study and did not require informed patient consent. A validated Monte Carlo program was used to perform simulations in 42 pediatric patient models (age range, 0-16 years; weight range, 2-80 kg; 24 boys, 18 girls). Multidetector CT scanners were modeled on those from two commercial manufacturers (LightSpeed VCT, GE Healthcare, Waukesha, Wis; SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). Organ doses were estimated for each patient model for routine chest and abdominopelvic examinations and were normalized by volume CT dose index (CTDI(vol)). The relationships between CTDI(vol)-normalized organ dose coefficients and average patient diameters were evaluated across scanner models. For organs within the image coverage, CTDI(vol)-normalized organ dose coefficients largely showed a strong exponential relationship with the average patient diameter (R(2) > 0.9). The average percentage differences between the two scanner models were generally within 10%. For distributed organs and organs on the periphery of or outside the image coverage, the differences were generally larger (average, 3%-32%) mainly because of the effect of overranging. It is feasible to estimate patient-specific organ dose for a given examination with the knowledge of patient size and the CTDI(vol). These CTDI(vol)-normalized organ dose coefficients enable one to readily estimate patient-specific organ dose for pediatric patients in clinical settings. This dose information, and, as appropriate, attendant risk estimations, can provide more substantive information for the individual patient for both clinical and research applications and can yield more expansive information on dose profiles across patient populations within a practice. �

Pediatric Chest and Abdominopelvic CT: Organ Dose Estimation Based on 42 Patient Models

PubMed Central

Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Paulson, Erik K.; Frush, Donald P.

2014-01-01

Purpose To estimate organ dose from pediatric chest and abdominopelvic computed tomography (CT) examinations and evaluate the dependency of organ dose coefficients on patient size and CT scanner models. Materials and Methods The institutional review board approved this HIPAA–compliant study and did not require informed patient consent. A validated Monte Carlo program was used to perform simulations in 42 pediatric patient models (age range, 0–16 years; weight range, 2–80 kg; 24 boys, 18 girls). Multidetector CT scanners were modeled on those from two commercial manufacturers (LightSpeed VCT, GE Healthcare, Waukesha, Wis; SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). Organ doses were estimated for each patient model for routine chest and abdominopelvic examinations and were normalized by volume CT dose index (CTDIvol). The relationships between CTDIvol-normalized organ dose coefficients and average patient diameters were evaluated across scanner models. Results For organs within the image coverage, CTDIvol-normalized organ dose coefficients largely showed a strong exponential relationship with the average patient diameter (R2 > 0.9). The average percentage differences between the two scanner models were generally within 10%. For distributed organs and organs on the periphery of or outside the image coverage, the differences were generally larger (average, 3%–32%) mainly because of the effect of overranging. Conclusion It is feasible to estimate patient-specific organ dose for a given examination with the knowledge of patient size and the CTDIvol. These CTDIvol-normalized organ dose coefficients enable one to readily estimate patient-specific organ dose for pediatric patients in clinical settings. This dose information, and, as appropriate, attendant risk estimations, can provide more substantive information for the individual patient for both clinical and research applications and can yield more expansive information on dose profiles

The estimation of galactic cosmic ray penetration and dose rates

NASA Technical Reports Server (NTRS)

Burrell, M. O.; Wright, J. J.

1972-01-01

This study is concerned with approximation methods that can be readily applied to estimate the absorbed dose rate from cosmic rays in rads - tissue or rems inside simple geometries of aluminum. The present work is limited to finding the dose rate at the center of spherical shells or behind plane slabs. The dose rate is calculated at tissue-point detectors or for thin layers of tissue. This study considers cosmic-rays dose rates for both free-space and earth-orbiting missions.

Accuracy of patient specific organ-dose estimates obtained using an automated image segmentation algorithm

NASA Astrophysics Data System (ADS)

Gilat-Schmidt, Taly; Wang, Adam; Coradi, Thomas; Haas, Benjamin; Star-Lack, Josh

2016-03-01

The overall goal of this work is to develop a rapid, accurate and fully automated software tool to estimate patient-specific organ doses from computed tomography (CT) scans using a deterministic Boltzmann Transport Equation solver and automated CT segmentation algorithms. This work quantified the accuracy of organ dose estimates obtained by an automated segmentation algorithm. The investigated algorithm uses a combination of feature-based and atlas-based methods. A multiatlas approach was also investigated. We hypothesize that the auto-segmentation algorithm is sufficiently accurate to provide organ dose estimates since random errors at the organ boundaries will average out when computing the total organ dose. To test this hypothesis, twenty head-neck CT scans were expertly segmented into nine regions. A leave-one-out validation study was performed, where every case was automatically segmented with each of the remaining cases used as the expert atlas, resulting in nineteen automated segmentations for each of the twenty datasets. The segmented regions were applied to gold-standard Monte Carlo dose maps to estimate mean and peak organ doses. The results demonstrated that the fully automated segmentation algorithm estimated the mean organ dose to within 10% of the expert segmentation for regions other than the spinal canal, with median error for each organ region below 2%. In the spinal canal region, the median error was 7% across all data sets and atlases, with a maximum error of 20%. The error in peak organ dose was below 10% for all regions, with a median error below 4% for all organ regions. The multiple-case atlas reduced the variation in the dose estimates and additional improvements may be possible with more robust multi-atlas approaches. Overall, the results support potential feasibility of an automated segmentation algorithm to provide accurate organ dose estimates.

Dose estimates for the solid waste performance assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rittman, P.D.

1994-08-30

The Solid Waste Performance Assessment calculations by PNL in 1990 were redone to incorporate changes in methods and parameters since then. The ten scenarios found in their report were reduced to three, the Post-Drilling Resident, the Post-Excavation Resident, and an All Pathways Irrigator. In addition, estimates of population dose to people along the Columbia River are also included. The attached report describes the methods and parameters used in the calculations, and derives dose factors for each scenario. In addition, waste concentrations, ground water concentrations, and river water concentrations needed to reach the performance objectives of 100 mrem/yr and 500 person-rem/yrmore » are computed. Internal dose factors from DOE-0071 were applied when computing internal dose. External dose rate factors came from the GENII Version 1.485 software package. Dose calculations were carried out on a spreadsheet. The calculations are described in detail in the report for 63 nuclides, including 5 not presently in the GENII libraries. The spreadsheet calculations were checked by comparison with GENII, as described in Appendix D.« less

Estimating adolescent sleep need using dose-response modeling.

PubMed

Short, Michelle A; Weber, Nathan; Reynolds, Chelsea; Coussens, Scott; Carskadon, Mary A

2018-04-01

This study will (1) estimate the nightly sleep need of human adolescents, (2) determine the time course and severity of sleep-related deficits when sleep is reduced below this optimal quantity, and (3) determine whether sleep restriction perturbs the circadian system as well as the sleep homeostat. Thirty-four adolescents aged 15 to 17 years spent 10 days and nine nights in the sleep laboratory. Between two baseline nights and two recovery nights with 10 hours' time in bed (TIB) per night, participants experienced either severe sleep restriction (5-hour TIB), moderate sleep restriction (7.5-hour TIB), or no sleep restriction (10-hour TIB) for five nights. A 10-minute psychomotor vigilance task (PVT; lapse = response after 500 ms) and the Karolinska Sleepiness Scale were administered every 3 hours during wake. Salivary dim-light melatonin onset was calculated at baseline and after four nights of each sleep dose to estimate circadian phase. Dose-dependent deficits to sleep duration, circadian phase timing, lapses of attention, and subjective sleepiness occurred. Less TIB resulted in less sleep, more lapses of attention, greater subjective sleepiness, and larger circadian phase delays. Sleep need estimated from 10-hour TIB sleep opportunities was approximately 9 hours, while modeling PVT lapse data suggested that 9.35 hours of sleep is needed to maintain optimal sustained attention performance. Sleep restriction perturbs homeostatic and circadian systems, leading to dose-dependent deficits to sustained attention and sleepiness. Adolescents require more sleep for optimal functioning than typically obtained.

Maxine: A spreadsheet for estimating dose from chronic atmospheric radioactive releases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jannik, Tim; Bell, Evaleigh; Dixon, Kenneth

MAXINE is an EXCEL© spreadsheet, which is used to estimate dose to individuals for routine and accidental atmospheric releases of radioactive materials. MAXINE does not contain an atmospheric dispersion model, but rather doses are estimated using air and ground concentrations as input. Minimal input is required to run the program and site specific parameters are used when possible. Complete code description, verification of models, and user’s manual have been included.

Estimation of breast dose reduction potential for organ-based tube current modulated CT with wide dose reduction arc

NASA Astrophysics Data System (ADS)

Fu, Wanyi; Sturgeon, Gregory M.; Agasthya, Greeshma; Segars, W. Paul; Kapadia, Anuj J.; Samei, Ehsan

2017-03-01

This study aimed to estimate the organ dose reduction potential for organ-dose-based tube current modulated (ODM) thoracic CT with wide dose reduction arc. Twenty-one computational anthropomorphic phantoms (XCAT, age range: 27- 75 years, weight range: 52.0-105.8 kg) were used to create a virtual patient population with clinical anatomic variations. For each phantom, two breast tissue compositions were simulated: 50/50 and 20/80 (glandular-to-adipose ratio). A validated Monte Carlo program was used to estimate the organ dose for standard tube current modulation (TCM) (SmartmA, GE Healthcare) and ODM (GE Healthcare) for a commercial CT scanner (Revolution, GE Healthcare) with explicitly modeled tube current modulation profile, scanner geometry, bowtie filtration, and source spectrum. Organ dose was determined using a typical clinical thoracic CT protocol. Both organ dose and CTDIvol-to-organ dose conversion coefficients (h factors) were compared between TCM and ODM. ODM significantly reduced all radiosensitive organ doses (p<0.01). The breast dose was reduced by 30+/-2%. For h factors, organs in the anterior region (e.g. thyroid, stomach) exhibited substantial decreases, and the medial, distributed, and posterior region either saw an increase or no significant change. The organ-dose-based tube current modulation significantly reduced organ doses especially for radiosensitive superficial anterior organs such as the breasts.

Estimating occupancy probability of moose using hunter survey data

USGS Publications Warehouse

Crum, Nathan J.; Fuller, Angela K.; Sutherland, Christopher S.; Cooch, Evan G.; Hurst, Jeremy E.

2017-01-01

Monitoring rare species can be difficult, especially across large spatial extents, making conventional methods of population monitoring costly and logistically challenging. Citizen science has the potential to produce observational data across large areas that can be used to monitor wildlife distributions using occupancy models. We used citizen science (i.e., hunter surveys) to facilitate monitoring of moose (Alces alces) populations, an especially important endeavor because of their recent apparent declines in the northeastern and upper midwestern regions of the United States. To better understand patterns of occurrence of moose in New York, we used data collected through an annual survey of approximately 11,000 hunters between 2012 and 2014 that recorded detection–non-detection data of moose and other species. We estimated patterns of occurrence of moose in relation to land cover characteristics, climate effects, and interspecific interactions using occupancy models to analyze spatially referenced moose observations. Coniferous and deciduous forest with low prevalence of white-tailed deer (Odocoileus virginianus) had the highest probability of moose occurrence. This study highlights the potential of data collected using citizen science for understanding the spatial distribution of low-density species across large spatial extents and providing key information regarding where and when future research and management activities should be focused.

Estimated collective effective dose to the population from nuclear medicine examinations in Slovenia

PubMed Central

Skrk, Damijan; Zontar, Dejan

2013-01-01

Background A national survey of patient exposure from nuclear medicine diagnostic procedures was performed by Slovenian Radiation Protection Administration in order to estimate their contribution to the collective effective dose to the population of Slovenia. Methods A set of 36 examinations with the highest contributions to the collective effective dose was identified. Data about frequencies and average administered activities of radioisotopes used for those examinations were collected from all nuclear medicine departments in Slovenia. A collective effective dose to the population and an effective dose per capita were estimated from the collected data using dose conversion factors. Results The total collective effective dose to the population from nuclear medicine diagnostic procedures in 2011 was estimated to 102 manSv, giving an effective dose per capita of 0.05 mSv. Conclusions The comparison of results of this study with studies performed in other countries indicates that the nuclear medicine providers in Slovenia are well aware of the importance of patient protection measures and of optimisation of procedures. PMID:24133396

Estimation of benefit of prevention of occupational cancer for comparative risk assessment: methods and examples.

PubMed

Lee, Lukas Jyuhn-Hsiarn; Chang, Yu-Yin; Liou, Saou-Hsing; Wang, Jung-Der

2012-08-01

To quantify the life years gained and financial savings by preventing a case of occupational cancer. The authors retrieved data from the Taiwan Cancer Registry and linked them with the National Mortality Registry to estimate the survival functions for major occupational cancers: lung, pleural mesothelioma, urinary bladder and leukaemia. Assuming a constant excess hazard for each type of cancer, the authors extrapolated lifetime survival functions by the Monte Carlo method. For each patient with cancer, the authors simulated an age- and gender-matched person without cancer based on vital statistics of Taiwan to estimate life expectancy and expected years of life lost (EYLL). By using the reimbursement data from the National Health Insurance Research Database, the authors calculated the average monthly healthcare expenditures, which were summed to estimate the lifetime healthcare expenditures after adjusting for the corresponding monthly survival probability. A total of 51,408, 136, 12,891 and 5285 new cases of lung, pleural mesothelioma, bladder and leukaemia cancers, respectively, were identified during 1997-2005 and followed until the end of 2007. The EYLL was predicted to be 13.7±0.1, 18.9±0.7, 4.7±0.3 and 19.4±0.5 years for these cancers, respectively, and the lifetime healthcare expenditures with a 3% annual discount were predicted to be US$22,359, US$14,900, US$51,987 and US$59,741, respectively. The burden of these occupational cancers, in terms of EYLL and lifetime healthcare expenditures, was substantial. Such estimates may provide useful empirical evidence for comparative risk assessment that can be applied in health policy-making and clinical decision-making.

Data linkage to estimate the extent and distribution of occupational disease: new onset adult asthma in Alberta, Canada.

PubMed

Cherry, Nicola; Beach, Jeremy; Burstyn, Igor; Fan, Xiangning; Guo, Na; Kapur, Nitin

2009-11-01

Although occupational asthma is a well recognized and preventable disease, the numbers of cases presenting for compensation may be far lower than the true incidence. Workers' Compensation Board (WCB) claims for any reason 1995-2004 were linked to physician billing data. New onset adult asthma (NOAA) was defined as a billing for asthma (ICD-9 code of 493) in the 12 months prior to a WCB claim without asthma in the previous 3 years. Incidence was calculated by occupation, industry and, in a case-referent analysis, exposures estimated from an asthma specific job exposure matrix. There were 782,908 WCB eligible claims, with an incidence rate for NOAA of 1.6%: 23 occupations and 21 industries had a significantly increased risk. Isocyanates (OR 1.54: 95% CI 1.01-2.36) and exposure to mixed agricultural allergens (OR = 1.59: 95% CI 1.17-2.18) were related to NOAA overall, as were exposures to cleaning chemicals in men (OR = 1.91:95% CI 1.34-2.73). Estimates of the number of cases of occupational asthma suggested a range of 4% to about half for the proportion compensated. Data linkage of administrative records can demonstrate under-reporting of occupational asthma and indicate areas for prevention. (c) 2009 Wiley-Liss, Inc.

Deterministic absorbed dose estimation in computed tomography using a discrete ordinates method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norris, Edward T.; Liu, Xin, E-mail: xinliu@mst.edu; Hsieh, Jiang

Purpose: Organ dose estimation for a patient undergoing computed tomography (CT) scanning is very important. Although Monte Carlo methods are considered gold-standard in patient dose estimation, the computation time required is formidable for routine clinical calculations. Here, the authors instigate a deterministic method for estimating an absorbed dose more efficiently. Methods: Compared with current Monte Carlo methods, a more efficient approach to estimating the absorbed dose is to solve the linear Boltzmann equation numerically. In this study, an axial CT scan was modeled with a software package, Denovo, which solved the linear Boltzmann equation using the discrete ordinates method. Themore » CT scanning configuration included 16 x-ray source positions, beam collimators, flat filters, and bowtie filters. The phantom was the standard 32 cm CT dose index (CTDI) phantom. Four different Denovo simulations were performed with different simulation parameters, including the number of quadrature sets and the order of Legendre polynomial expansions. A Monte Carlo simulation was also performed for benchmarking the Denovo simulations. A quantitative comparison was made of the simulation results obtained by the Denovo and the Monte Carlo methods. Results: The difference in the simulation results of the discrete ordinates method and those of the Monte Carlo methods was found to be small, with a root-mean-square difference of around 2.4%. It was found that the discrete ordinates method, with a higher order of Legendre polynomial expansions, underestimated the absorbed dose near the center of the phantom (i.e., low dose region). Simulations of the quadrature set 8 and the first order of the Legendre polynomial expansions proved to be the most efficient computation method in the authors’ study. The single-thread computation time of the deterministic simulation of the quadrature set 8 and the first order of the Legendre polynomial expansions was 21 min on a personal

Estimating the social cost of respiratory cancer cases attributable to occupational exposures in France.

PubMed

Serrier, Hassan; Sultan-Taieb, Hélène; Luce, Danièle; Bejean, Sophie

2014-07-01

The objective of this article was to estimate the social cost of respiratory cancer cases attributable to occupational risk factors in France in 2010. According to the attributable fraction method and based on available epidemiological data from the literature, we estimated the number of respiratory cancer cases due to each identified risk factor. We used the cost-of-illness method with a prevalence-based approach. We took into account the direct and indirect costs. We estimated the cost of production losses due to morbidity (absenteeism and presenteeism) and mortality costs (years of production losses) in the market and nonmarket spheres. The social cost of lung, larynx, sinonasal and mesothelioma cancer caused by exposure to asbestos, chromium, diesel engine exhaust, paint, crystalline silica, wood and leather dust in France in 2010 were estimated at between 917 and 2,181 million euros. Between 795 and 2,011 million euros (87-92%) of total costs were due to lung cancer alone. Asbestos was by far the risk factor representing the greatest cost to French society in 2010 at between 531 and 1,538 million euros (58-71%), ahead of diesel engine exhaust, representing an estimated social cost of between 233 and 336 million euros, and crystalline silica (119-229 million euros). Indirect costs represented about 66% of total costs. Our assessment shows the magnitude of the economic impact of occupational respiratory cancers. It allows comparisons between countries and provides valuable information for policy-makers responsible for defining public health priorities.

The Dose Response Relationship between In Ear Occupational Noise Exposure and Hearing Loss

PubMed Central

Rabinowitz, Peter M.; Galusha, Deron; Dixon-Ernst, Christine; Clougherty, Jane E.; Neitzel, Richard L.

2014-01-01

Objectives Current understanding of the dose-response relationship between occupational noise and hearing loss is based on cross-sectional studies prior to the widespread use hearing protection and with limited data regarding noise exposures below 85dBA. We report on the hearing loss experience of a unique cohort of industrial workers with daily monitoring of noise inside of hearing protection devices. Methods At an industrial facility, workers exhibiting accelerated hearing loss were enrolled in a mandatory program to monitor daily noise exposures inside of hearing protection. We compared these noise measurements (as time-weighted LAVG) to interval rates of high frequency hearing loss over a six year period using a mixed effects model, adjusting for potential confounders. Results Workers’ high frequency hearing levels at study inception averaged more than 40 dB hearing threshold level (HTL). Most noise exposures were less than 85dBA (mean LAVG 76 dBA, interquartile range 74 to 80 dBA). We found no statistical relationship between LAvg and high frequency hearing loss (p = 0.53). Using a metric for monthly maximum noise exposure did not improve model fit. Conclusion At-ear noise exposures below 85dBA did not show an association with risk of high frequency hearing loss among workers with substantial past noise exposure and hearing loss at baseline. Therefore, effective noise control to below 85dBA may lead to significant reduction in occupational hearing loss risk in such individuals. Further research is needed on the dose response relationship of noise and hearing loss in individuals with normal hearing and little prior noise exposure. PMID:23825197

Estimating the Occupational Morbidity for Migrant and Seasonal Farmworkers in New York State: a Comparison of Two Methods

PubMed Central

Earle-Richardson, Giulia B.; Brower, Melissa A.; Jones, Amanda M.; May, John J.; Jenkins, Paul L.

2008-01-01

Purpose To compare occupational morbidity estimates for migrant and seasonal farmworkers obtained from survey methods versus chart review methods, and to estimate the proportion of morbidity treated at federally recognized migrant health centers (MHCs) in a highly agricultural region of New York. Methods Researchers simultaneously conducted: a) an occupational injury and illness survey among agricultural workers; b) MHC chart review; and c) hospital emergency room (ER) chart reviews. Results Of the 24 injuries reported by 550 survey subjects, 54.2% received treatment MHCs 16.7% at ERs, 16.7% at some other facility, and 12.5% were untreated. For injuries treated at MHCs or ERs, the incidence density based on survey methods was 29.3 injuries per 10,000 worker-weeks versus 27.4 by chart review. The standardized morbidity ratio (SMR) for this comparison was 1.07 (95% CI = 0.65 – 1.77). Conclusion Survey data indicate that 71% of agricultural injury and illness can be captured with MHC and ER chart review. MHC and ER incidence density estimates show strong correspondence between the two methods. A chart review-based surveillance system, in conjunction with a correction factor based on periodic worker surveys, would provide a cost-effective estimate of the occupational illness and injury rate in this population. PMID:18063238

Estimation of external dose by car-borne survey in Kerala, India.

PubMed

Hosoda, Masahiro; Tokonami, Shinji; Omori, Yasutaka; Sahoo, Sarata Kumar; Akiba, Suminori; Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Nair, Raghu Ram; Jayalekshmi, Padmavathy Amma; Sebastian, Paul; Iwaoka, Kazuki; Akata, Naofumi; Kudo, Hiromi

2015-01-01

A car-borne survey was carried out in Kerala, India to estimate external dose. Measurements were made with a 3-in × 3-in NaI(Tl) scintillation spectrometer from September 23 to 27, 2013. The routes were selected from 12 Panchayats in Karunagappally Taluk which were classified into high level, mid-level and low level high background radiation (HBR) areas. A heterogeneous distribution of air kerma rates was seen in the dose rate distribution map. The maximum air kerma rate, 2.1 μGy/h, was observed on a beach sand surface. 232Th activity concentration for the beach sand was higher than that for soil and grass surfaces, and the range of activity concentration was estimated to be 0.7-2.3 kBq/kg. The contribution of 232Th to air kerma rate was over 70% at the measurement points with values larger than 0.34 μGy/h. The maximum value of the annual effective dose in Karunagappally Taluk was observed around coastal areas, and it was estimated to be 13 mSv/y. More than 30% of all the annual effective doses obtained in this survey exceeded 1 mSv/y.

Estimates of internal-dose equivalent from inhalation and ingestion of selected radionuclides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunning, D.E.

1982-01-01

This report presents internal radiation dose conversion factors for radionuclides of interest in environmental assessments of nuclear fuel cycles. This volume provides an updated summary of estimates of committed dose equivalent for radionuclides considered in three previous Oak Ridge National Laboratory (ORNL) reports. Intakes by inhalation and ingestion are considered. The International Commission on Radiological Protection (ICRP) Task Group Lung Model has been used to simulate the deposition and retention of particulate matter in the respiratory tract. Results corresponding to activity median aerodynamic diameters (AMAD) of 0.3, 1.0, and 5.0 ..mu..m are given. The gastorintestinal (GI) tract has been representedmore » by a four-segment catenary model with exponential transfer of radioactivity from one segment to the next. Retention of radionuclides in systemic organs is characterized by linear combinations of decaying exponential functions, recommended in ICRP Publication 30. The first-year annual dose rate, maximum annual dose rate, and fifty-year dose commitment per microcurie intake of each radionuclide is given for selected target organs and the effective dose equivalent. These estimates include contributions from specified source organs plus the systemic activity residing in the rest of the body; cross irradiation due to penetrating radiations has been incorporated into these estimates. 15 references.« less

Neutron track length estimator for GATE Monte Carlo dose calculation in radiotherapy.

PubMed

Elazhar, H; Deschler, T; Létang, J M; Nourreddine, A; Arbor, N

2018-06-20

The out-of-field dose in radiation therapy is a growing concern in regards to the late side-effects and secondary cancer induction. In high-energy x-ray therapy, the secondary neutrons generated through photonuclear reactions in the accelerator are part of this secondary dose. The neutron dose is currently not estimated by the treatment planning system while it appears to be preponderant for distances greater than 50 cm from the isocenter. Monte Carlo simulation has become the gold standard for accurately calculating the neutron dose under specific treatment conditions but the method is also known for having a slow statistical convergence, which makes it difficult to be used on a clinical basis. The neutron track length estimator, a neutron variance reduction technique inspired by the track length estimator method has thus been developped for the first time in the Monte Carlo code GATE to allow a fast computation of the neutron dose in radiotherapy. The details of its implementation, as well as the comparison of its performances against the analog MC method, are presented here. A gain of time from 15 to 400 can be obtained by our method, with a mean difference in the dose calculation of about 1% in comparison with the analog MC method.

The relative importance of whole body vibration and occupational lifting as risk factors for low-back pain

PubMed Central

Palmer, K; Griffin, M; Syddall, H; Pannett, B; Cooper, C; Coggon, D

2003-01-01

Aims: To explore the impact of occupational exposure to whole body vibration (WBV) on low back pain (LBP) in the general population and to estimate the burden of LBP attributable to occupational WBV in comparison with that due to occupational lifting. Methods: A questionnaire including sections on WBV at work, LBP, and potential risk factors was mailed to a community sample of 22 194 men and women of working age. Sources and durations of exposure to occupational WBV were ascertained for the past week and personal vibration doses (eVDV) were estimated. Analysis was confined to subjects reporting exposures in the past week as typical of their work. Associations of LBP with eVDV, driving industrial vehicles, and occupational lifting were explored by logistic regression and attributable numbers were calculated. Results: Significant associations were found between daily lifting of weights greater than 10 kg at work and LBP, troublesome LBP (which made it difficult to put on hosiery), and sciatica (prevalence ratios 1.3 to 1.7); but the risk of these outcomes in both sexes varied little by eVDV and only weak associations were found with riding on industrial vehicles. Assuming causal associations, the numbers of cases of LBP in Britain attributable to occupational WBV were estimated to be 444 000 in men and 95 000 in women. This compared with an estimated 940 000 male cases and 370 000 female cases of LBP from occupational lifting. Conclusions: The burden of LBP in Britain from occupational exposure to WBV is smaller than that attributable to lifting at work. PMID:14504358

A Discordance Weighting Approach Estimating Occupational and Income Returns to Education.

PubMed

Andersson, Matthew A

2018-04-23

Schooling differences between identical twins are often utilized as a natural experiment to estimate returns to education. Despite longstanding doubts about the truly random nature of within-twin-pair schooling discordance, such discordance has not yet been understood comprehensively, in terms of diverse between- and within-family peer, academic, familial, social, and health exposures. Here, a predictive analysis using national U.S. midlife twin data shows that within-pair schooling differences are endogenous to a variety of childhood exposures. Using discordance propensities, returns to education under a true natural experiment are simulated. Results for midlife occupation and income reveal differences in estimated returns to education that are statistically insignificant, suggesting that twin-based estimates of causal effects are robust. Moreover, identical and fraternal twins show similar levels of discordance endogeneity and similar responses to propensity weighting, suggesting that the identical twins may not provide demonstrably better leverage in the causal identification of educational returns.

Absence from work due to occupational and non-occupational accidents.

PubMed

Jørgensen, Kirsten; Laursen, Bjarne

2013-02-01

The aim of the present study was to investigate absence from work in Denmark due to occupational and non-occupational accidents. Since the beginning of the last decade, political focus has been placed on the population's working capacity and the scope of absence due to illness. Absence from work is estimated at between 3% and 6% of working hours in the EU and costs are estimated at approximately 2.5% of GNP. Victims of accidents treated at two emergency departments were interviewed regarding absence for the injured, the family and others. All answers were linked to the hospital information on the injury, so that it was possible to examine the relation between absence and injury type, and cause of the accident. In total, 1,479 injured persons were interviewed. 36% of these reported absence from work by themselves or others. In mean, an injury caused 3.21 days of absence. Based on this the total absence due to injuries in Denmark was estimated to 1,822,000 workdays, corresponding to approximately 6% of the total absence from work due to all types of illness. Non-occupational injuries resulted in more absence than did occupational injuries. Absence due to accidents contributed to a considerable part of the total absence from work, and non-occupational accidents caused more absence than did occupational accidents.

Grid occupancy estimation for environment perception based on belief functions and PCR6

NASA Astrophysics Data System (ADS)

Moras, Julien; Dezert, Jean; Pannetier, Benjamin

2015-05-01

In this contribution, we propose to improve the grid map occupancy estimation method developed so far based on belief function modeling and the classical Dempster's rule of combination. Grid map offers a useful representation of the perceived world for mobile robotics navigation. It will play a major role for the security (obstacle avoidance) of next generations of terrestrial vehicles, as well as for future autonomous navigation systems. In a grid map, the occupancy of each cell representing a small piece of the surrounding area of the robot must be estimated at first from sensors measurements (typically LIDAR, or camera), and then it must also be classified into different classes in order to get a complete and precise perception of the dynamic environment where the robot moves. So far, the estimation and the grid map updating have been done using fusion techniques based on the probabilistic framework, or on the classical belief function framework thanks to an inverse model of the sensors. Mainly because the latter offers an interesting management of uncertainties when the quality of available information is low, and when the sources of information appear as conflicting. To improve the performances of the grid map estimation, we propose in this paper to replace Dempster's rule of combination by the PCR6 rule (Proportional Conflict Redistribution rule #6) proposed in DSmT (Dezert-Smarandache) Theory. As an illustrating scenario, we consider a platform moving in dynamic area and we compare our new realistic simulation results (based on a LIDAR sensor) with those obtained by the probabilistic and the classical belief-based approaches.

Estimation of 1945 to 1957 food consumption. Hanford Environmental Dose Reconstruction Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, D.M.; Bates, D.J.; Marsh, T.L.

This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. Themore » report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.« less

Estimation of benefit of prevention of occupational cancer for comparative risk assessment: methods and examples

PubMed Central

Lee, Lukas Jyuhn-Hsiarn; Chang, Yu-Yin; Liou, Saou-Hsing

2012-01-01

Objectives To quantify the life years gained and financial savings by preventing a case of occupational cancer. Methods The authors retrieved data from the Taiwan Cancer Registry and linked them with the National Mortality Registry to estimate the survival functions for major occupational cancers: lung, pleural mesothelioma, urinary bladder and leukaemia. Assuming a constant excess hazard for each type of cancer, the authors extrapolated lifetime survival functions by the Monte Carlo method. For each patient with cancer, the authors simulated an age- and gender-matched person without cancer based on vital statistics of Taiwan to estimate life expectancy and expected years of life lost (EYLL). By using the reimbursement data from the National Health Insurance Research Database, the authors calculated the average monthly healthcare expenditures, which were summed to estimate the lifetime healthcare expenditures after adjusting for the corresponding monthly survival probability. Results A total of 51 408, 136, 12 891 and 5285 new cases of lung, pleural mesothelioma, bladder and leukaemia cancers, respectively, were identified during 1997–2005 and followed until the end of 2007. The EYLL was predicted to be 13.7±0.1, 18.9±0.7, 4.7±0.3 and 19.4±0.5 years for these cancers, respectively, and the lifetime healthcare expenditures with a 3% annual discount were predicted to be US$22 359, US$14 900, US$51 987 and US$59 741, respectively. Conclusions The burden of these occupational cancers, in terms of EYLL and lifetime healthcare expenditures, was substantial. Such estimates may provide useful empirical evidence for comparative risk assessment that can be applied in health policy-making and clinical decision-making. PMID:22576592

SU-E-T-129: Are Knowledge-Based Planning Dose Estimates Valid for Distensible Organs?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalonde, R; Heron, D; Huq, M

2015-06-15

Purpose: Knowledge-based planning programs have become available to assist treatment planning in radiation therapy. Such programs can be used to generate estimated DVHs and planning constraints for organs at risk (OARs), based upon a model generated from previous plans. These estimates are based upon the planning CT scan. However, for distensible OARs like the bladder and rectum, daily variations in volume may make the dose estimates invalid. The purpose of this study is to determine whether knowledge-based DVH dose estimates may be valid for distensible OARs. Methods: The Varian RapidPlan™ knowledge-based planning module was used to generate OAR dose estimatesmore » and planning objectives for 10 prostate cases previously planned with VMAT, and final plans were calculated for each. Five weekly setup CBCT scans of each patient were then downloaded and contoured (assuming no change in size and shape of the target volume), and rectum and bladder DVHs were recalculated for each scan. Dose volumes were then compared at 75, 60,and 40 Gy for the bladder and rectum between the planning scan and the CBCTs. Results: Plan doses and estimates matched well at all dose points., Volumes of the rectum and bladder varied widely between planning CT and the CBCTs, ranging from 0.46 to 2.42 for the bladder and 0.71 to 2.18 for the rectum, causing relative dose volumes to vary between planning CT and CBCT, but absolute dose volumes were more consistent. The overall ratio of CBCT/plan dose volumes was 1.02 ±0.27 for rectum and 0.98 ±0.20 for bladder in these patients. Conclusion: Knowledge-based planning dose volume estimates for distensible OARs are still valid, in absolute volume terms, between treatment planning scans and CBCT’s taken during daily treatment. Further analysis of the data is being undertaken to determine how differences depend upon rectum and bladder filling state. This work has been supported by Varian Medical Systems.« less

Ladtap XL Version 2017: A Spreadsheet For Estimating Dose Resulting From Aqueous Releases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minter, K.; Jannik, T.

LADTAP XL© is an EXCEL© spreadsheet used to estimate dose to offsite individuals and populations resulting from routine and accidental releases of radioactive materials to the Savannah River. LADTAP XL© contains two worksheets: LADTAP and IRRIDOSE. The LADTAP worksheet estimates dose for environmental pathways including external exposure resulting from recreational activities on the Savannah River and internal exposure resulting from ingestion of water, fish, and invertebrates originating from the Savannah River. IRRIDOSE estimates offsite dose to individuals and populations from irrigation of foodstuffs with contaminated water from the Savannah River. In 2004, a complete description of the LADTAP XL© codemore » and an associated user’s manual was documented in LADTAP XL©: A Spreadsheet for Estimating Dose Resulting from Aqueous Release (WSRC-TR-2004-00059) and revised input parameters, dose coefficients, and radionuclide decay constants were incorporated into LADTAP XL© Version 2013 (SRNL-STI-2011-00238). LADTAP XL© Version 2017 is a slight modification to Version 2013 with minor changes made for more user-friendly parameter inputs and organization, updates in the time conversion factors used within the dose calculations, and fixed an issue with the expected time build-up parameter referenced within the population shoreline dose calculations. This manual has been produced to update the code description, verification of the models, and provide an updated user’s manual. LADTAP XL© Version 2017 has been verified by Minter (2017) and is ready for use at the Savannah River Site (SRS).« less

Potential uncertainty reduction in model-averaged benchmark dose estimates informed by an additional dose study.

PubMed

Shao, Kan; Small, Mitchell J

2011-10-01

A methodology is presented for assessing the information value of an additional dosage experiment in existing bioassay studies. The analysis demonstrates the potential reduction in the uncertainty of toxicity metrics derived from expanded studies, providing insights for future studies. Bayesian methods are used to fit alternative dose-response models using Markov chain Monte Carlo (MCMC) simulation for parameter estimation and Bayesian model averaging (BMA) is used to compare and combine the alternative models. BMA predictions for benchmark dose (BMD) are developed, with uncertainty in these predictions used to derive the lower bound BMDL. The MCMC and BMA results provide a basis for a subsequent Monte Carlo analysis that backcasts the dosage where an additional test group would have been most beneficial in reducing the uncertainty in the BMD prediction, along with the magnitude of the expected uncertainty reduction. Uncertainty reductions are measured in terms of reduced interval widths of predicted BMD values and increases in BMDL values that occur as a result of this reduced uncertainty. The methodology is illustrated using two existing data sets for TCDD carcinogenicity, fitted with two alternative dose-response models (logistic and quantal-linear). The example shows that an additional dose at a relatively high value would have been most effective for reducing the uncertainty in BMA BMD estimates, with predicted reductions in the widths of uncertainty intervals of approximately 30%, and expected increases in BMDL values of 5-10%. The results demonstrate that dose selection for studies that subsequently inform dose-response models can benefit from consideration of how these models will be fit, combined, and interpreted. © 2011 Society for Risk Analysis.

ICRP Publication 139: Occupational Radiological Protection in Interventional Procedures.

PubMed

López, P Ortiz; Dauer, L T; Loose, R; Martin, C J; Miller, D L; Vañó, E; Doruff, M; Padovani, R; Massera, G; Yoder, C

2018-03-01

In recent publications, such as Publications 117 and 120, the Commission provided practical advice for physicians and other healthcare personnel on measures to protect their patients and themselves during interventional procedures. These measures can only be effective if they are encompassed by a framework of radiological protection elements, and by the availability of professionals with responsibilities in radiological protection. This framework includes a radiological protection programme with a strategy for exposure monitoring, protective garments, education and training, and quality assurance of the programme implementation. Professionals with responsibilities in occupational radiological protection for interventional procedures include: medical physicists; radiological protection specialists; personnel working in dosimetry services; clinical applications support personnel from the suppliers and maintenance companies; staff engaged in training, standardisation of equipment, and procedures; staff responsible for occupational health; hospital administrators responsible for providing financial support; and professional bodies and regulators. This publication addresses these elements and these audiences, and provides advice on specific issues, such as assessment of effective dose from dosimeter readings when an apron is worn, estimation of exposure of the lens of the eye (with and without protective eyewear), extremity monitoring, selection and testing of protective garments, and auditing the interventional procedures when occupational doses are unusually high or low (the latter meaning that the dosimeter may not have been worn).

Technical note: estimating absorbed doses to the thyroid in CT.

PubMed

Huda, Walter; Magill, Dennise; Spampinato, Maria V

2011-06-01

To describe a method for estimating absorbed doses to the thyroid in patients undergoing neck CT examinations. Thyroid doses in anthropomorphic phantoms were obtained for all 23 scanner dosimetry data sets in the ImPACT CT patient dosimetry calculator. Values of relative thyroid dose [R(thy)(L)], defined as the thyroid dose for a given scan length (L) divided by the corresponding thyroid dose for a whole body scan, were determined for neck CT scans. Ratios of the maximum thyroid dose to the corresponding CTDI(vol) and [D'(thy)], were obtained for two phantom diameters. The mass-equivalent water cylinder of any patient can be derived from the neck cross-sectional area and the corresponding average Hounsfield Unit, and compared to the 16.5-cm diameter water cylinder that models the ImPACT anthropomorphic phantom neck. Published values of relative doses in water cylinders of varying diameter were used to adjust thyroid doses in the anthropomorphic phantom to those of any sized patient. Relative thyroid doses R(thy)(L) increase to unity with increasing scan length and with very small difference between scanners. A 10-cm scan centered on the thyroid would result in a dose that is, nearly 90% of the thyroid dose from a whole body scan when performed using the constant radiographic techniques. At 120 kV, the average value of D'(thy) for the 16-cm diameter was 1.17 +/- 0.05 and was independent of CT vendor and year of CT scanner, and choice of x-ray tube voltage. The corresponding average value of D'(thy) in the 32-cm diameter phantom was 2.28 +/- 0.22 and showed marked variations depending on vendor, year of introduction into clinical practice as well as x-ray tube voltage. At 120 kV, a neck equivalent to a 10-cm diameter cylinder of water would have thyroid doses 36% higher than those in the ImPACT phantom, whereas a neck equivalent to a 25-cm cylinder diameter would have thyroid doses 35% lower. Patient thyroid doses can be estimated by taking into account the amount of

Estimating occupancy and predicting numbers of gray wolf packs in Montana using hunter surveys

USGS Publications Warehouse

Rich, Lindsey N.; Russell, Robin E.; Glenn, Elizabeth M.; Mitchell, Michael S.; Gude, Justin A.; Podruzny, Kevin M.; Sime, Carolyn A.; Laudon, Kent; Ausband, David E.; Nichols, James D.

2013-01-01

Reliable knowledge of the status and trend of carnivore populations is critical to their conservation and management. Methods for monitoring carnivores, however, are challenging to conduct across large spatial scales. In the Northern Rocky Mountains, wildlife managers need a time- and cost-efficient method for monitoring gray wolf (Canis lupus) populations. Montana Fish, Wildlife and Parks (MFWP) conducts annual telephone surveys of >50,000 deer and elk hunters. We explored how survey data on hunters' sightings of wolves could be used to estimate the occupancy and distribution of wolf packs and predict their abundance in Montana for 2007–2009. We assessed model utility by comparing our predictions to MFWP minimum known number of wolf packs. We minimized false positive detections by identifying a patch as occupied if 2–25 wolves were detected by ≥3 hunters. Overall, estimates of the occupancy and distribution of wolf packs were generally consistent with known distributions. Our predictions of the total area occupied increased from 2007 to 2009 and predicted numbers of wolf packs were approximately 1.34–1.46 times the MFWP minimum counts for each year of the survey. Our results indicate that multi-season occupancy models based on public sightings can be used to monitor populations and changes in the spatial distribution of territorial carnivores across large areas where alternative methods may be limited by personnel, time, accessibility, and budget constraints.

Occupancy estimation and modeling with multiple states and state uncertainty

USGS Publications Warehouse

Nichols, J.D.; Hines, J.E.; MacKenzie, D.I.; Seamans, M.E.; Gutierrez, R.J.

2007-01-01

The distribution of a species over space is of central interest in ecology, but species occurrence does not provide all of the information needed to characterize either the well-being of a population or the suitability of occupied habitat. Recent methodological development has focused on drawing inferences about species occurrence in the face of imperfect detection. Here we extend those methods by characterizing occupied locations by some additional state variable ( e. g., as producing young or not). Our modeling approach deals with both detection probabilities,1 and uncertainty in state classification. We then use the approach with occupancy and reproductive rate data from California Spotted Owls (Strix occidentalis occidentalis) collected in the central Sierra Nevada during the breeding season of 2004 to illustrate the utility of the modeling approach. Estimates of owl reproductive rate were larger than naive estimates, indicating the importance of appropriately accounting for uncertainty in detection and state classification.

Neutron dose estimation in a zero power nuclear reactor

NASA Astrophysics Data System (ADS)

Triviño, S.; Vedelago, J.; Cantargi, F.; Keil, W.; Figueroa, R.; Mattea, F.; Chautemps, A.; Santibañez, M.; Valente, M.

2016-10-01

This work presents the characterization and contribution of neutron and gamma components to the absorbed dose in a zero power nuclear reactor. A dosimetric method based on Fricke gel was implemented to evaluate the separation between dose components in the mixed field. The validation of this proposed method was performed by means of direct measurements of neutron flux in different positions using Au and Mg-Ni activation foils. Monte Carlo simulations were conversely performed using the MCNP main code with a dedicated subroutine to incorporate the exact complete geometry of the nuclear reactor facility. Once nuclear fuel elements were defined, the simulations computed the different contributions to the absorbed dose in specific positions inside the core. Thermal/epithermal contributions of absorbed dose were assessed by means of Fricke gel dosimetry using different isotopic compositions aimed at modifying the sensitivity of the dosimeter for specific dose components. Clear distinctions between gamma and neutron capture dose were obtained. Both Monte Carlo simulations and experimental results provided reliable estimations about neutron flux rate as well as dose rate during the reactor operation. Simulations and experimental results are in good agreement in every positions measured and simulated in the core.

Cardiac-Specific Conversion Factors to Estimate Radiation Effective Dose From Dose-Length Product in Computed Tomography.

PubMed

Trattner, Sigal; Halliburton, Sandra; Thompson, Carla M; Xu, Yanping; Chelliah, Anjali; Jambawalikar, Sachin R; Peng, Boyu; Peters, M Robert; Jacobs, Jill E; Ghesani, Munir; Jang, James J; Al-Khalidi, Hussein; Einstein, Andrew J

2018-01-01

This study sought to determine updated conversion factors (k-factors) that would enable accurate estimation of radiation effective dose (ED) for coronary computed tomography angiography (CTA) and calcium scoring performed on 12 contemporary scanner models and current clinical cardiac protocols and to compare these methods to the standard chest k-factor of 0.014 mSv·mGy -1 cm -1 . Accurate estimation of ED from cardiac CT scans is essential to meaningfully compare the benefits and risks of different cardiac imaging strategies and optimize test and protocol selection. Presently, ED from cardiac CT is generally estimated by multiplying a scanner-reported parameter, the dose-length product, by a k-factor which was determined for noncardiac chest CT, using single-slice scanners and a superseded definition of ED. Metal-oxide-semiconductor field-effect transistor radiation detectors were positioned in organs of anthropomorphic phantoms, which were scanned using all cardiac protocols, 120 clinical protocols in total, on 12 CT scanners representing the spectrum of scanners from 5 manufacturers (GE, Hitachi, Philips, Siemens, Toshiba). Organ doses were determined for each protocol, and ED was calculated as defined in International Commission on Radiological Protection Publication 103. Effective doses and scanner-reported dose-length products were used to determine k-factors for each scanner model and protocol. k-Factors averaged 0.026 mSv·mGy -1 cm -1 (95% confidence interval: 0.0258 to 0.0266) and ranged between 0.020 and 0.035 mSv·mGy -1 cm -1 . The standard chest k-factor underestimates ED by an average of 46%, ranging from 30% to 60%, depending on scanner, mode, and tube potential. Factors were higher for prospective axial versus retrospective helical scan modes, calcium scoring versus coronary CTA, and higher (100 to 120 kV) versus lower (80 kV) tube potential and varied among scanner models (range of average k-factors: 0.0229 to 0.0277 mSv·mGy -1 cm -1 ). Cardiac k

Exposure to potential occupational asthmogens: prevalence data from the National Occupational Exposure Survey.

PubMed

de la Hoz, R E; Young, R O; Pedersen, D H

1997-02-01

Few data are available about the prevalence of occupational exposures to agents which can cause occupational asthma or aggravate preexisting asthma (asthmogens). Using potential occupational exposure data from the National Occupational Exposure Survey (NOES) of 1980-1983, we investigated the number of asthmogen exposures, asthmogen-exposure(s) per production worker, and unprotected occupational asthmogen exposures in different industries and occupations. Data for the entire United States were used to generate estimates of occupational exposure at two selected state and local levels. It was estimated that 7,864,000 workers in the surveyed industries were potentially exposed to one or more occupational asthmogen(s) in the United States. The average number of observed potential exposures per asthmogen-exposed worker was 4.4, and varied from 11.9, in the Water Transportation industry, to 1.2 in Local and Suburban transportation. The largest number of observed potential exposures was recorded in the Apparel and Other Finished Products (garment) industry. This work and further analyses using this approach are expected to contribute to a better understanding of the epidemiology of occupational asthma, and to serve as a guide to target future occupational asthma surveillance efforts.

Estimation of neutron dose equivalent at the mezzanine of the Advanced Light Source and the laboratory boundary using the ORNL program MORSE.

PubMed

Sun, R K

1990-12-01

To investigate the radiation effect of neutrons near the Advanced Light Source (ALS) at Lawrence Berkeley Laboratory (LBL) with respect to the neutron dose equivalents in nearby occupied areas and at the site boundary, the neutron transport code MORSE, from Oak Ridge National Laboratory (ORNL), was used. These dose equivalents result from both skyshine neutrons transported by air scattering and direct neutrons penetrating the shielding. The ALS neutron sources are a 50-MeV linear accelerator and its transfer line, a 1.5-GeV booster, a beam extraction line, and a 1.9-GeV storage ring. The most conservative total occupational-dose-equivalent rate in the center of the ALS mezzanine, 39 m from the ALS center, was found to be 1.14 X 10(-3) Sv y-1 per 2000-h "occupational" year, and the total environmental-dose-equivalent rate at the ALS boundary, 125 m from the ALS center, was found to be 3.02 X 10(-4) Sv y-1 per 8760-h calendar year. More realistic dose-equivalent rates, using the nominal (expected) storage-ring current, were calculated to be 1.0 X 10(-4) Sv y-1 and 2.65 X 10(-5) Sv y-1 occupational year and calendar year, respectively, which are much lower than the DOE reporting levels.

Incorporating a Capability for Estimating Inhalation Doses in ...

EPA Pesticide Factsheets

Report and Data Files This report presents the approach to be used to incorporate in the U.S. Environmental Protection Agency’s TEVA-SPOT software (U.S.EPA 2014) a capability for estimating inhalation doses that result from the most important sources of contaminated aerosols and volatile contaminants during a contamination event.

Occupational cancer in Britain

PubMed Central

Van Tongeren, Martie; Jimenez, Araceli S; Hutchings, Sally J; MacCalman, Laura; Rushton, Lesley; Cherrie, John W

2012-01-01

To estimate the current occupational cancer burden due to past exposures in Britain, estimates of the number of exposed workers at different levels are required, as well as risk estimates of cancer due to the exposures. This paper describes the methods and results for estimating the historical exposures. All occupational carcinogens or exposure circumstances classified by the International Agency for Research on Cancer as definite or probable human carcinogens and potentially to be found in British workplaces over the past 20–40 years were included in this study. Estimates of the number of people exposed by industrial sector were based predominantly on two sources of data, the CARcinogen EXposure (CAREX) database and the UK Labour Force Survey. Where possible, multiple and overlapping exposures were taken into account. Dose–response risk estimates were generally not available in the epidemiological literature for the cancer–exposure pairs in this study, and none of the sources available for obtaining the numbers exposed provided data by different levels of exposure. Industrial sectors were therefore assigned using expert judgement to ‘higher'- and ‘lower'-exposure groups based on the similarity of exposure to the population in the key epidemiological studies from which risk estimates had been selected. Estimates of historical exposure prevalence were obtained for 41 carcinogens or occupational circumstances. These include exposures to chemicals and metals, combustion products, other mixtures or groups of chemicals, mineral and biological dusts, physical agents and work patterns, as well as occupations and industries that have been associated with increased risk of cancer, but for which the causative agents are unknown. There were more than half a million workers exposed to each of six carcinogens (radon, solar radiation, crystalline silica, mineral oils, non-arsenical insecticides and 2,3,7,8-tetrachlorodibenzo-p-dioxin); other agents to which a large

NIRS external dose estimation system for Fukushima residents after the Fukushima Dai-ichi NPP accident.

PubMed

Akahane, Keiichi; Yonai, Shunsuke; Fukuda, Shigekazu; Miyahara, Nobuyuki; Yasuda, Hiroshi; Iwaoka, Kazuki; Matsumoto, Masaki; Fukumura, Akifumi; Akashi, Makoto

2013-01-01

The great east Japan earthquake and subsequent tsunamis caused Fukushima Dai-ichi Nuclear Power Plant (NPP) accident. National Institute of Radiological Sciences (NIRS) developed the external dose estimation system for Fukushima residents. The system is being used in the Fukushima health management survey. The doses can be obtained by superimposing the behavior data of the residents on the dose rate maps. For grasping the doses, 18 evacuation patterns of the residents were assumed by considering the actual evacuation information before using the survey data. The doses of the residents from the deliberate evacuation area were relatively higher than those from the area within 20 km radius. The estimated doses varied from around 1 to 6 mSv for the residents evacuated from the representative places in the deliberate evacuation area. The maximum dose in 18 evacuation patterns was estimated to be 19 mSv.

NIRS external dose estimation system for Fukushima residents after the Fukushima Dai-ichi NPP accident

NASA Astrophysics Data System (ADS)

Akahane, Keiichi; Yonai, Shunsuke; Fukuda, Shigekazu; Miyahara, Nobuyuki; Yasuda, Hiroshi; Iwaoka, Kazuki; Matsumoto, Masaki; Fukumura, Akifumi; Akashi, Makoto

2013-04-01

The great east Japan earthquake and subsequent tsunamis caused Fukushima Dai-ichi Nuclear Power Plant (NPP) accident. National Institute of Radiological Sciences (NIRS) developed the external dose estimation system for Fukushima residents. The system is being used in the Fukushima health management survey. The doses can be obtained by superimposing the behavior data of the residents on the dose rate maps. For grasping the doses, 18 evacuation patterns of the residents were assumed by considering the actual evacuation information before using the survey data. The doses of the residents from the deliberate evacuation area were relatively higher than those from the area within 20 km radius. The estimated doses varied from around 1 to 6 mSv for the residents evacuated from the representative places in the deliberate evacuation area. The maximum dose in 18 evacuation patterns was estimated to be 19 mSv.

Radiotherapy for glioma during pregnancy: fetal dose estimates, risk assessment and clinical management.

PubMed

Haba, Y; Twyman, N; Thomas, S J; Overton, C; Dendy, P; Burnet, N G

2004-05-01

Cancer in pregnancy is relatively uncommon, but constitutes a major problem. We report the measurement of scatter dose to the fetus and the estimated fetal risk from that exposure in an illustrative case of a patient, 20 weeks pregnant, with a grade 3 anaplastic astrocytoma. A clinical decision was made to withhold radiotherapy, if possible, until after delivery. Sequential magnetic resonance imaging (MRI) showed no progression during the pregnancy. In the event, she was managed conservatively until the successful completion of her pregnancy. In case radiotherapy was required, an estimation of the fetal risk was made. Phantom measurements were undertaken to assess the likely fetal dose. Film badges were used to estimate the scattered radiation energy. Measurements were made on a Varian 600C at 6 MV and Asea Brown Boveri (ABB) accelerator at 8 and 16 MV. Doses were measured at 30, 45 and 60 cm from the isocentre; the fetus was assumed to lie at about 60 cm and not closer than 45 cm from the isocentre. Estimated doses to the position of the fetus were lowest with the 6 MV Varian accelerator. Using this machine without additional abdominal shielding, the estimated dose on the surface at 45 cm from the tumour volume was 2.2 cGy for a tumour dose of 54 Gy; using the ABB accelerator, the dose varied between 49-59 cGy. The energy of scattered radiation was in the range 208-688 keV, so that additional shielding would be practical to further reduce the fetal dose. The risk of cancer up to the age of 15 years attributable to radiation is 1 in 1700 per cGy, of which half will be fatal (i.e. 1 in 3300 per cGy). A dose of 2.2 cGy adds a risk of fatal cancer by the age 15 years of only 1 in 1500. Because the addition of shielding might halve the fetal dose, this risk should be reduced to 1 in 3000. For comparison, the overall UK risk of cancer up to the age 15 years is 1 in 650. In conclusion, careful choice of linear accelerator for the treatment of a pregnant woman and the use

Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

NASA Astrophysics Data System (ADS)

Alva-Sánchez, Héctor; Reynoso-Mejía, Alberto; Casares-Cruz, Katiuzka; Taboada-Barajas, Jesús

2014-11-01

In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

Radiation dose to workers due to the inhalation of dust during granite fabrication.

PubMed

Zwack, L M; McCarthy, W B; Stewart, J H; McCarthy, J F; Allen, J G

2014-03-01

There has been very little research conducted to determine internal radiation doses resulting from worker exposure to ionising radiation in granite fabrication shops. To address this issue, we estimated the effective radiation dose of granite workers in US fabrication shops who were exposed to the maximum respirable dust and silica concentrations allowed under current US regulations, and also to concentrations reported in the literature. Radiation doses were calculated using standard methods developed by the International Commission on Radiological Protection. The calculated internal doses were very low, and below both US occupational standards (50 mSv yr(-1)) and limits applicable to the general public (1 mSv yr(-1)). Workers exposed to respirable granite dust concentrations at the US Occupational Safety and Health Administration (OSHA) respirable dust permissible exposure limit (PEL) of 5 mg m(-3) over a full year had an estimated radiation dose of 0.062 mSv yr(-1). Workers exposed to respirable granite dust concentrations at the OSHA silica PEL and at the American Conference of Governmental Industrial Hygienists Threshold Limit Value for a full year had expected radiation doses of 0.007 mSv yr(-1) and 0.002 mSv yr(-1), respectively. Using data from studies of respirable granite dust and silica concentrations measured in granite fabrication shops, we calculated median expected radiation doses that ranged from <0.001 to 0.101 mSv yr(-1).

How safe are federal regulations on occupational alcohol use?

PubMed

Howland, Jonathan; Almeida, Alissa; Rohsenow, Damaris; Minsky, Sara; Greece, Jacey

2006-01-01

Current US federal regulations on occupational alcohol use for safety-sensitive jobs do not account for impairment from low doses of alcohol and next day effects of heavy drinking. Research on the effects of low doses of alcohol on neurocognitive and simulated occupational tasks suggests that the current per se level of these regulations is set too high. Research on the effects of heavy drinking on next-day neurocognitive and simulated occupational performance is mixed and suggests that further research is needed to determine the safety of current "bottle-to-throttle" times. Although low-dose and residual drinking effects may pose low relative risk for occupational error, the aggregate contribution of these exposures to workplace problems may be substantial, given the number of people exposed.

Patient-based estimation of organ dose for a population of 58 adult patients across 13 protocol categories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahbaee, Pooyan, E-mail: psahbae@ncsu.edu; Segars, W. Paul; Samei, Ehsan

2014-07-15

Purpose: This study aimed to provide a comprehensive patient-specific organ dose estimation across a multiplicity of computed tomography (CT) examination protocols. Methods: A validated Monte Carlo program was employed to model a common CT system (LightSpeed VCT, GE Healthcare). The organ and effective doses were estimated from 13 commonly used body and neurological CT examination. The dose estimation was performed on 58 adult computational extended cardiac-torso phantoms (35 male, 23 female, mean age 51.5 years, mean weight 80.2 kg). The organ dose normalized by CTDI{sub vol} (h factor) and effective dose normalized by the dose length product (DLP) (k factor)more » were calculated from the results. A mathematical model was derived for the correlation between the h and k factors with the patient size across the protocols. Based on this mathematical model, a dose estimation iPhone operating system application was designed and developed to be used as a tool to estimate dose to the patients for a variety of routinely used CT examinations. Results: The organ dose results across all the protocols showed an exponential decrease with patient body size. The correlation was generally strong for the organs which were fully or partially located inside the scan coverage (Pearson sample correlation coefficient (r) of 0.49). The correlation was weaker for organs outside the scan coverage for which distance between the organ and the irradiation area was a stronger predictor of dose to the organ. For body protocols, the effective dose before and after normalization by DLP decreased exponentially with increasing patient's body diameter (r > 0.85). The exponential relationship between effective dose and patient's body diameter was significantly weaker for neurological protocols (r < 0.41), where the trunk length was a slightly stronger predictor of effective dose (0.15 < r < 0.46). Conclusions: While the most accurate estimation of a patient dose requires specific modeling of the

SU-F-P-44: A Direct Estimate of Peak Skin Dose for Interventional Fluoroscopy Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weir, V; Zhang, J

Purpose: There is an increasing demand for medical physicist to calculate peak skin dose (PSD) for interventional fluoroscopy procedures. The dose information (Dose-Area-Product and Air Kerma) displayed in the console cannot directly be used for this purpose. Our clinical experience shows that the use of the existing methods may overestimate or underestimate PSD. This study attempts to develop a direct estimate of PSD from the displayed dose metrics. Methods: An anthropomorphic torso phantom was used for dose measurements for a common fluoroscopic procedure. Entrance skin doses were measured with a Piranha solid state point detector placed on the table surfacemore » below the torso phantom. An initial “reference dose rate” (RE) measurement was conducted by comparing the displayed dose rate (mGy/min) to the dose rate measured. The distance from table top to focal spot was taken as the reference distance (RD at the RE. Table height was then adjusted. The displayed air kerma and DAP were recorded and sent to three physicists to estimate PSD. An inverse square correction was applied to correct displayed air kerma at various table heights. The PSD estimated by physicists and the PSD by the proposed method were then compared with the measurements. The estimated DAPs were compared to displayed DAP readings (mGycm2). Results: The difference between estimated PSD by the proposed method and direct measurements was less than 5%. For the same set of data, the estimated PSD by each of three physicists is different from measurements by ±52%. The DAP calculated by the proposed method and displayed DAP readings in the console is less than 20% at various table heights. Conclusion: PSD may be simply estimated from displayed air kerma or DAP if the distance between table top and tube focal spot or if x-ray beam area on table top is available.« less

Occupational radiation doses during interventional procedures

NASA Astrophysics Data System (ADS)

Nuraeni, N.; Hiswara, E.; Kartikasari, D.; Waris, A.; Haryanto, F.

2016-03-01

Digital subtraction angiography (DSA) is a type of fluoroscopy technique used in interventional radiology to clearly visualize blood vessels in a bony or dense soft tissue environment. The use of DSA procedures has been increased quite significantly in the Radiology departments in various cities in Indonesia. Various reports showed that both patients and medical staff received a noticeable radiation dose during the course of this procedure. A study had been carried out to measure these doses among interventionalist, nurse and radiographer. The results show that the interventionalist and the nurse, who stood quite close to the X-ray beams compared with the radiographer, received radiation higher than the others. The results also showed that the radiation dose received by medical staff were var depending upon the duration and their position against the X-ray beams. Compared tothe dose limits, however, the radiation dose received by all these three medical staff were still lower than the limits.

Patient dose estimation from CT scans at the Mexican National Neurology and Neurosurgery Institute

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alva-Sánchez, Héctor, E-mail: halva@ciencias.unam.mx; Reynoso-Mejía, Alberto; Casares-Cruz, Katiuzka

In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guidemore » provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimated radiation dose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiation dose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.« less

Establishing bounding internal dose estimates for thorium activities at Rocky Flats.

PubMed

Ulsh, Brant A; Rich, Bryce L; Chew, Melton H; Morris, Robert L; Sharfi, Mutty; Rolfes, Mark R

2008-07-01

As part of an evaluation of a Special Exposure Cohort petition filed on behalf of workers at the Rocky Flats Plant, the National Institute for Occupational Safety and Health (NIOSH) was required to demonstrate that bounding values could be established for radiation doses due to the potential intake of all radionuclides present at the facility. The main radioactive elements of interest at Rocky Flats were plutonium and uranium, but much smaller quantities of several other elements, including thorium, were occasionally handled at the site. Bounding potential doses from thorium has proven challenging at other sites due to the early historical difficulty in detecting this element through urinalysis methods and the relatively high internal dose delivered per unit intake. This paper reports the results of NIOSH's investigation of the uses of thorium at Rocky Flats and provides bounding dose reconstructions for these operations. During this investigation, NIOSH reviewed unclassified reports, unclassified extracts of classified materials, material balance and inventory ledgers, monthly progress reports from various groups, and health physics field logbooks, and conducted interviews with former Rocky Flats workers. Thorium operations included: (1) an experimental metal forming project with 240 kg of thorium in 1960; (2) the use of pre-formed parts in weapons mockups; (3) the removal of Th from U; (4) numerous analytical procedures involving trace quantities of thorium; and (5) the possible experimental use of thorium as a mold coating compound. The thorium handling operations at Rocky Flats were limited in scope, well-monitored and documented, and potential doses can be bounded.

Estimating patient dose from CT exams that use automatic exposure control: Development and validation of methods to accurately estimate tube current values.

PubMed

McMillan, Kyle; Bostani, Maryam; Cagnon, Christopher H; Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H; McNitt-Gray, Michael F

2017-08-01

The vast majority of body CT exams are performed with automatic exposure control (AEC), which adapts the mean tube current to the patient size and modulates the tube current either angularly, longitudinally or both. However, most radiation dose estimation tools are based on fixed tube current scans. Accurate estimates of patient dose from AEC scans require knowledge of the tube current values, which is usually unavailable. The purpose of this work was to develop and validate methods to accurately estimate the tube current values prescribed by one manufacturer's AEC system to enable accurate estimates of patient dose. Methods were developed that took into account available patient attenuation information, user selected image quality reference parameters and x-ray system limits to estimate tube current values for patient scans. Methods consistent with AAPM Report 220 were developed that used patient attenuation data that were: (a) supplied by the manufacturer in the CT localizer radiograph and (b) based on a simulated CT localizer radiograph derived from image data. For comparison, actual tube current values were extracted from the projection data of each patient. Validation of each approach was based on data collected from 40 pediatric and adult patients who received clinically indicated chest (n = 20) and abdomen/pelvis (n = 20) scans on a 64 slice multidetector row CT (Sensation 64, Siemens Healthcare, Forchheim, Germany). For each patient dataset, the following were collected with Institutional Review Board (IRB) approval: (a) projection data containing actual tube current values at each projection view, (b) CT localizer radiograph (topogram) and (c) reconstructed image data. Tube current values were estimated based on the actual topogram (actual-topo) as well as the simulated topogram based on image data (sim-topo). Each of these was compared to the actual tube current values from the patient scan. In addition, to assess the accuracy of each method in estimating

Estimation of 1945 to 1957 food consumption. Hanford Environmental Dose Reconstruction Project: Draft

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, D.M.; Bates, D.J.; Marsh, T.L.

This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. Themore » report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.« less

The Global Burden of Occupational Disease.

PubMed

Rushton, Lesley

2017-09-01

Burden of occupational disease estimation contributes to understanding of both magnitude and relative importance of different occupational hazards and provides essential information for targeting risk reduction. This review summarises recent key findings and discusses their impact on occupational regulation and practice. New methods have been developed to estimate burden of occupational disease that take account of the latency of many chronic diseases and allow for exposure trends and workforce turnover. Results from these studies have shown in several countries and globally that, in spite of improvements in workplace technology, practices and exposures over the last decades, occupational hazards remain an important cause of ill health and mortality worldwide. Major data gaps have been identified particularly regarding exposure information. Reliable data on employment and disease are also lacking especially in developing countries. Burden of occupational disease estimates form an important part of decision-making processes.

Automated face detection for occurrence and occupancy estimation in chimpanzees.

PubMed

Crunchant, Anne-Sophie; Egerer, Monika; Loos, Alexander; Burghardt, Tilo; Zuberbühler, Klaus; Corogenes, Katherine; Leinert, Vera; Kulik, Lars; Kühl, Hjalmar S

2017-03-01

Surveying endangered species is necessary to evaluate conservation effectiveness. Camera trapping and biometric computer vision are recent technological advances. They have impacted on the methods applicable to field surveys and these methods have gained significant momentum over the last decade. Yet, most researchers inspect footage manually and few studies have used automated semantic processing of video trap data from the field. The particular aim of this study is to evaluate methods that incorporate automated face detection technology as an aid to estimate site use of two chimpanzee communities based on camera trapping. As a comparative baseline we employ traditional manual inspection of footage. Our analysis focuses specifically on the basic parameter of occurrence where we assess the performance and practical value of chimpanzee face detection software. We found that the semi-automated data processing required only 2-4% of the time compared to the purely manual analysis. This is a non-negligible increase in efficiency that is critical when assessing the feasibility of camera trap occupancy surveys. Our evaluations suggest that our methodology estimates the proportion of sites used relatively reliably. Chimpanzees are mostly detected when they are present and when videos are filmed in high-resolution: the highest recall rate was 77%, for a false alarm rate of 2.8% for videos containing only chimpanzee frontal face views. Certainly, our study is only a first step for transferring face detection software from the lab into field application. Our results are promising and indicate that the current limitation of detecting chimpanzees in camera trap footage due to lack of suitable face views can be easily overcome on the level of field data collection, that is, by the combined placement of multiple high-resolution cameras facing reverse directions. This will enable to routinely conduct chimpanzee occupancy surveys based on camera trapping and semi

The dosimetric impact of including the patient table in CT dose estimates

NASA Astrophysics Data System (ADS)

Nowik, Patrik; Bujila, Robert; Kull, Love; Andersson, Jonas; Poludniowski, Gavin

2017-12-01

The purpose of this study was to evaluate the dosimetric impact of including the patient table in Monte Carlo CT dose estimates for both spiral scans and scan projection radiographs (SPR). CT scan acquisitions were simulated for a Siemens SOMATOM Force scanner (Siemens Healthineers, Forchheim, Germany) with and without a patient table present. An adult male, an adult female and a pediatric female voxelized phantom were simulated. The simulated scans included tube voltages of 80 and 120 kVp. Spiral scans simulated without a patient table resulted in effective doses that were overestimated by approximately 5% compared to the same simulations performed with the patient table present. Doses in selected individual organs (breast, colon, lung, red bone marrow and stomach) were overestimated by up to 8%. Effective doses from SPR acquired with the x-ray tube stationary at 6 o’clock (posterior-anterior) were overestimated by 14-23% when the patient table was not included, with individual organ dose discrepancies (breast, colon, lung red bone marrow and stomach) all exceeding 13%. The reference entrance skin dose to the back were in this situation overestimated by 6-15%. These results highlight the importance of including the patient table in patient dose estimates for such scan situations.

Model Uncertainty and Bayesian Model Averaged Benchmark Dose Estimation for Continuous Data

EPA Science Inventory

The benchmark dose (BMD) approach has gained acceptance as a valuable risk assessment tool, but risk assessors still face significant challenges associated with selecting an appropriate BMD/BMDL estimate from the results of a set of acceptable dose-response models. Current approa...

Derivation of an occupational exposure level for manganese in welding fumes.

PubMed

Bailey, Lisa A; Kerper, Laura E; Goodman, Julie E

2018-01-01

Exposure to high levels of manganese (Mn) in occupational settings is known to lead to adverse neurological effects. Since Mn is an essential nutrient, there are mechanisms that maintain its homeostatic control in the body, and there is some level of Mn in air that does not perturb Mn homeostasis. However, the Mn exposure concentrations at which no adverse effects are expected in occupational settings vary considerably across regulatory agencies. We set out to derive a Mn Occupational Exposure Level (OEL) for welders based on a review of studies that evaluated Mn exposure concentrations from welding fumes and: (1) neurological effects in welders; (2) levels of Mn in the brains of welders (via pallidal index [PI] estimated from magnetic resonance imaging [MRI]); (3) other biomarkers of Mn exposure in welders (i.e., blood and urine); and (4) Mn brain concentrations, PI, and corresponding neurological effects in non-human primates. Our analysis suggests uncertainty in quantifying dose-response associations for Mn from many of the occupational welding studies. The few welding studies that adequately estimate exposure suggest a possible OEL of 100-140μg/m 3 for respirable Mn. This range is consistent with other epidemiology studies, studies of biomarkers of Mn exposure in welders, and with studies in non-human primates, though future studies could provide a stronger basis for deriving a Mn occupational guideline for welders. Copyright © 2017 Elsevier B.V. All rights reserved.

Cardiovascular conditions, hearing difficulty, and occupational noise exposure within US industries and occupations.

PubMed

Kerns, Ellen; Masterson, Elizabeth A; Themann, Christa L; Calvert, Geoffrey M

2018-06-01

The purpose of this study was to estimate the prevalence of occupational noise exposure, hearing difficulty and cardiovascular conditions within US industries and occupations, and to examine any associations of these outcomes with occupational noise exposure. National Health Interview Survey data from 2014 were examined. Weighted prevalence and adjusted prevalence ratios of self-reported hearing difficulty, hypertension, elevated cholesterol, and coronary heart disease or stroke were estimated by level of occupational noise exposure, industry, and occupation. Twenty-five percent of current workers had a history of occupational noise exposure (14% exposed in the last year), 12% had hearing difficulty, 24% had hypertension, 28% had elevated cholesterol; 58%, 14%, and 9% of these cases can be attributed to occupational noise exposure, respectively. Hypertension, elevated cholesterol, and hearing difficulty are more prevalent among noise-exposed workers. Reducing workplace noise levels is critical. Workplace-based health and wellness programs should also be considered. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

A comparison study of size-specific dose estimate calculation methods.

PubMed

Parikh, Roshni A; Wien, Michael A; Novak, Ronald D; Jordan, David W; Klahr, Paul; Soriano, Stephanie; Ciancibello, Leslie; Berlin, Sheila C

2018-01-01

The size-specific dose estimate (SSDE) has emerged as an improved metric for use by medical physicists and radiologists for estimating individual patient dose. Several methods of calculating SSDE have been described, ranging from patient thickness or attenuation-based (automated and manual) measurements to weight-based techniques. To compare the accuracy of thickness vs. weight measurement of body size to allow for the calculation of the size-specific dose estimate (SSDE) in pediatric body CT. We retrospectively identified 109 pediatric body CT examinations for SSDE calculation. We examined two automated methods measuring a series of level-specific diameters of the patient's body: method A used the effective diameter and method B used the water-equivalent diameter. Two manual methods measured patient diameter at two predetermined levels: the superior endplate of L2, where body width is typically most thin, and the superior femoral head or iliac crest (for scans that did not include the pelvis), where body width is typically most thick; method C averaged lateral measurements at these two levels from the CT projection scan, and method D averaged lateral and anteroposterior measurements at the same two levels from the axial CT images. Finally, we used body weight to characterize patient size, method E, and compared this with the various other measurement methods. Methods were compared across the entire population as well as by subgroup based on body width. Concordance correlation (ρ c ) between each of the SSDE calculation methods (methods A-E) was greater than 0.92 across the entire population, although the range was wider when analyzed by subgroup (0.42-0.99). When we compared each SSDE measurement method with CTDI vol, there was poor correlation, ρ c <0.77, with percentage differences between 20.8% and 51.0%. Automated computer algorithms are accurate and efficient in the calculation of SSDE. Manual methods based on patient thickness provide acceptable dose

Eye lens dose in interventional cardiology.

PubMed

Principi, S; Delgado Soler, C; Ginjaume, M; Beltran Vilagrasa, M; Rovira Escutia, J J; Duch, M A

2015-07-01

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. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The conversion of exposures due to radon into the effective dose: the epidemiological approach.

PubMed

Beck, T R

2017-11-01

The risks and dose conversion coefficients for residential and occupational exposures due to radon were determined with applying the epidemiological risk models to ICRP representative populations. The dose conversion coefficient for residential radon was estimated with a value of 1.6 mSv year -1 per 100 Bq m -3 (3.6 mSv per WLM), which is significantly lower than the corresponding value derived from the biokinetic and dosimetric models. The dose conversion coefficient for occupational exposures with applying the risk models for miners was estimated with a value of 14 mSv per WLM, which is in good accordance with the results of the dosimetric models. To resolve the discrepancy regarding residential radon, the ICRP approaches for the determination of risks and doses were reviewed. It could be shown that ICRP overestimates the risk for lung cancer caused by residential radon. This can be attributed to a wrong population weighting of the radon-induced risks in its epidemiological approach. With the approach in this work, the average risks for lung cancer were determined, taking into account the age-specific risk contributions of all individuals in the population. As a result, a lower risk coefficient for residential radon was obtained. The results from the ICRP biokinetic and dosimetric models for both, the occupationally exposed working age population and the whole population exposed to residential radon, can be brought in better accordance with the corresponding results of the epidemiological approach, if the respective relative radiation detriments and a radiation-weighting factor for alpha particles of about ten are used.

Comparison of internal dose estimates obtained using organ-level, voxel S value, and Monte Carlo techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grimes, Joshua, E-mail: grimes.joshua@mayo.edu; Celler, Anna

2014-09-15

Purpose: The authors’ objective was to compare internal dose estimates obtained using the Organ Level Dose Assessment with Exponential Modeling (OLINDA/EXM) software, the voxel S value technique, and Monte Carlo simulation. Monte Carlo dose estimates were used as the reference standard to assess the impact of patient-specific anatomy on the final dose estimate. Methods: Six patients injected with{sup 99m}Tc-hydrazinonicotinamide-Tyr{sup 3}-octreotide were included in this study. A hybrid planar/SPECT imaging protocol was used to estimate {sup 99m}Tc time-integrated activity coefficients (TIACs) for kidneys, liver, spleen, and tumors. Additionally, TIACs were predicted for {sup 131}I, {sup 177}Lu, and {sup 90}Y assuming themore » same biological half-lives as the {sup 99m}Tc labeled tracer. The TIACs were used as input for OLINDA/EXM for organ-level dose calculation and voxel level dosimetry was performed using the voxel S value method and Monte Carlo simulation. Dose estimates for {sup 99m}Tc, {sup 131}I, {sup 177}Lu, and {sup 90}Y distributions were evaluated by comparing (i) organ-level S values corresponding to each method, (ii) total tumor and organ doses, (iii) differences in right and left kidney doses, and (iv) voxelized dose distributions calculated by Monte Carlo and the voxel S value technique. Results: The S values for all investigated radionuclides used by OLINDA/EXM and the corresponding patient-specific S values calculated by Monte Carlo agreed within 2.3% on average for self-irradiation, and differed by as much as 105% for cross-organ irradiation. Total organ doses calculated by OLINDA/EXM and the voxel S value technique agreed with Monte Carlo results within approximately ±7%. Differences between right and left kidney doses determined by Monte Carlo were as high as 73%. Comparison of the Monte Carlo and voxel S value dose distributions showed that each method produced similar dose volume histograms with a minimum dose covering 90% of the volume

Gamma-H2AX-based dose estimation for whole and partial body radiation exposure.

PubMed

Horn, Simon; Barnard, Stephen; Rothkamm, Kai

2011-01-01

Most human exposures to ionising radiation are partial body exposures. However, to date only limited tools are available for rapid and accurate estimation of the dose distribution and the extent of the body spared from the exposure. These parameters are of great importance for emergency triage and clinical management of exposed individuals. Here, measurements of γ-H2AX immunofluorescence by microscopy and flow cytometry were compared as rapid biodosimetric tools for whole and partial body exposures. Ex vivo uniformly X-irradiated blood lymphocytes from one donor were used to generate a universal biexponential calibration function for γ-H2AX foci/intensity yields per unit dose for time points up to 96 hours post exposure. Foci--but not intensity--levels remained significantly above background for 96 hours for doses of 0.5 Gy or more. Foci-based dose estimates for ex vivo X-irradiated blood samples from 13 volunteers were in excellent agreement with the actual dose delivered to the targeted samples. Flow cytometric dose estimates for X-irradiated blood samples from 8 volunteers were in excellent agreement with the actual dose delivered at 1 hour post exposure but less so at 24 hours post exposure. In partial body exposures, simulated by mixing ex vivo irradiated and unirradiated lymphocytes, foci/intensity distributions were significantly over-dispersed compared to uniformly irradiated lymphocytes. For both methods and in all cases the estimated fraction of irradiated lymphocytes and dose to that fraction, calculated using the zero contaminated Poisson test and γ-H2AX calibration function, were in good agreement with the actual mixing ratios and doses delivered to the samples. In conclusion, γ-H2AX analysis of irradiated lymphocytes enables rapid and accurate assessment of whole body doses while dispersion analysis of foci or intensity distributions helps determine partial body doses and the irradiated fraction size in cases of partial body exposures.

Perturbation analysis for patch occupancy dynamics

USGS Publications Warehouse

Martin, Julien; Nichols, James D.; McIntyre, Carol L.; Ferraz, Goncalo; Hines, James E.

2009-01-01

Perturbation analysis is a powerful tool to study population and community dynamics. This article describes expressions for sensitivity metrics reflecting changes in equilibrium occupancy resulting from small changes in the vital rates of patch occupancy dynamics (i.e., probabilities of local patch colonization and extinction). We illustrate our approach with a case study of occupancy dynamics of Golden Eagle (Aquila chrysaetos) nesting territories. Examination of the hypothesis of system equilibrium suggests that the system satisfies equilibrium conditions. Estimates of vital rates obtained using patch occupancy models are used to estimate equilibrium patch occupancy of eagles. We then compute estimates of sensitivity metrics and discuss their implications for eagle population ecology and management. Finally, we discuss the intuition underlying our sensitivity metrics and then provide examples of ecological questions that can be addressed using perturbation analyses. For instance, the sensitivity metrics lead to predictions about the relative importance of local colonization and local extinction probabilities in influencing equilibrium occupancy for rare and common species.

Estimating radiation dose to organs of patients undergoing conventional and novel multidetector CT exams using Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Angel, Erin

Advances in Computed Tomography (CT) technology have led to an increase in the modality's diagnostic capabilities and therefore its utilization, which has in turn led to an increase in radiation exposure to the patient population. As a result, CT imaging currently constitutes approximately half of the collective exposure to ionizing radiation from medical procedures. In order to understand the radiation risk, it is necessary to estimate the radiation doses absorbed by patients undergoing CT imaging. The most widely accepted risk models are based on radiosensitive organ dose as opposed to whole body dose. In this research, radiosensitive organ dose was estimated using Monte Carlo based simulations incorporating detailed multidetector CT (MDCT) scanner models, specific scan protocols, and using patient models based on accurate patient anatomy and representing a range of patient sizes. Organ dose estimates were estimated for clinical MDCT exam protocols which pose a specific concern for radiosensitive organs or regions. These dose estimates include estimation of fetal dose for pregnant patients undergoing abdomen pelvis CT exams or undergoing exams to diagnose pulmonary embolism and venous thromboembolism. Breast and lung dose were estimated for patients undergoing coronary CTA imaging, conventional fixed tube current chest CT, and conventional tube current modulated (TCM) chest CT exams. The correlation of organ dose with patient size was quantified for pregnant patients undergoing abdomen/pelvis exams and for all breast and lung dose estimates presented. Novel dose reduction techniques were developed that incorporate organ location and are specifically designed to reduce close to radiosensitive organs during CT acquisition. A generalizable model was created for simulating conventional and novel attenuation-based TCM algorithms which can be used in simulations estimating organ dose for any patient model. The generalizable model is a significant contribution of this

A bounding estimate of neutron dose based on measured photon dose around single pass reactors at the Hanford site.

PubMed

Taulbee, Timothy D; Glover, Samuel E; Macievic, Gregory V; Hunacek, Mickey; Smith, Cheryl; DeBord, Gary W; Morris, Donald; Fix, Jack

2010-07-01

Neutron and photon radiation survey records have been used to evaluate and develop a neutron to photon (NP) ratio to reconstruct neutron doses to workers around Hanford's single pass reactors that operated from 1945 to 1972. A total of 5,773 paired neutron and photon measurements extracted from 57 boxes of survey records were used in the development of the NP ratio. The development of the NP ratio enables the use of the recorded dose from an individual's photon dosimeter badge to be used to estimate the unmonitored neutron dose. The Pearson rank correlation between the neutron and photon measurements was 0.71. The NP ratio best fit a lognormal distribution with a geometric mean (GM) of 0.8, a geometric standard deviation (GSD) of 2.95, and the upper 95 th % of this distribution was 4.75. An estimate of the neutron dose based on this NP ratio is considered bounding due to evidence that up to 70% of the total photon exposure received by workers around the single pass reactors occurs during shutdown maintenance and refueling activities when there is no significant neutron exposure. Thus when this NP ratio is applied to the total measured photon dose from an individual film badge dosimeter, the resulting neutron dose is considered bounded.

Radiation dose from MDCT using Monte Carlo simulations: estimating fetal dose due to pulmonary embolism scans accounting for overscan

NASA Astrophysics Data System (ADS)

Angel, E.; Wellnitz, C.; Goodsitt, M.; DeMarco, J.; Cagnon, C.; Ghatali, M.; Cody, D.; Stevens, D.; McCollough, C.; Primak, A.; McNitt-Gray, M.

2007-03-01

Pregnant women with shortness of breath are increasingly referred for CT Angiography to rule out Pulmonary Embolism (PE). While this exam is typically focused on the lungs, extending scan boundaries and overscan can add to the irradiated volume and have implications on fetal dose. The purpose of this work was to estimate radiation dose to the fetus when various levels of overscan were encountered. Two voxelized models of pregnant patients derived from actual patient anatomy were created based on image data. The models represent an early (< 7 weeks) and late term pregnancy (36 weeks). A previously validated Monte Carlo model of an MDCT scanner was used that takes into account physical details of the scanner. Simulated helical scans used 120 kVp, 4x5 mm beam collimation, pitch 1, and varying beam-off locations (edge of the irradiated volume) were used to represent different protocols plus overscan. Normalized dose (mGy/100mAs) was calculated for each fetus. For the early term and the late term pregnancy models, fetal dose estimates for a standard thoracic PE exam were estimated to be 0.05 and 0.3 mGy/100mAs, respectively, increasing to 9 mGy/100mAs when the beam-off location was extended to encompass the fetus. When performing PE exams to rule out PE in pregnant patients, the beam-off location may have a large effect on fetal dose, especially for late term pregnancies. Careful consideration of ending location of the x-ray beam - and not the end of image data - could result in significant reduction in radiation dose to the fetus.

SU-F-I-33: Estimating Radiation Dose in Abdominal Fat Quantitative CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, X; Yang, K; Liu, B

Purpose: To compare size-specific dose estimate (SSDE) in abdominal fat quantitative CT with another dose estimate D{sub size,L} that also takes into account scan length. Methods: This study complied with the requirements of the Health Insurance Portability and Accountability Act. At our institution, abdominal fat CT is performed with scan length = 1 cm and CTDI{sub vol} = 4.66 mGy (referenced to body CTDI phantom). A previously developed CT simulation program was used to simulate single rotation axial scans of 6–55 cm diameter water cylinders, and dose integral of the longitudinal dose profile over the central 1 cm length wasmore » used to predict the dose at the center of one-cm scan range. SSDE and D{sub size,L} were assessed for 182 consecutive abdominal fat CT examinations with mean water-equivalent diameter (WED) of 27.8 cm ± 6.0 (range, 17.9 - 42.2 cm). Patient age ranged from 18 to 75 years, and weight ranged from 39 to 163 kg. Results: Mean SSDE was 6.37 mGy ± 1.33 (range, 3.67–8.95 mGy); mean D{sub size,L} was 2.99 mGy ± 0.85 (range, 1.48 - 4.88 mGy); and mean D{sub size,L}/SSDE ratio was 0.46 ± 0.04 (range, 0.40 - 0.55). Conclusion: The conversion factors for size-specific dose estimate in AAPM Report No. 204 were generated using 15 - 30 cm scan lengths. One needs to be cautious in applying SSDE to small length CT scans. For abdominal fat CT, SSDE was 80–150% higher than the dose of 1 cm scan length.« less

Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses

PubMed Central

2014-01-01

Carbon nanotubes are commercially-important products of nanotechnology; however, their low density and small size makes carbon nanotube respiratory exposures likely during their production or processing. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to single-walled carbon nanotubes (SWCNT). In this study, we examined whether multi-walled carbon nanotubes (MWCNT) cause mitotic spindle damage in cultured cells at doses equivalent to 34 years of exposure at the NIOSH Recommended Exposure Limit (REL). MWCNT induced a dose responsive increase in disrupted centrosomes, abnormal mitotic spindles and aneuploid chromosome number 24 hours after exposure to 0.024, 0.24, 2.4 and 24 μg/cm2 MWCNT. Monopolar mitotic spindles comprised 95% of disrupted mitoses. Three-dimensional reconstructions of 0.1 μm optical sections showed carbon nanotubes integrated with microtubules, DNA and within the centrosome structure. Cell cycle analysis demonstrated a greater number of cells in S-phase and fewer cells in the G2 phase in MWCNT-treated compared to diluent control, indicating a G1/S block in the cell cycle. The monopolar phenotype of the disrupted mitotic spindles and the G1/S block in the cell cycle is in sharp contrast to the multi-polar spindle and G2 block in the cell cycle previously observed following exposure to SWCNT. One month following exposure to MWCNT there was a dramatic increase in both size and number of colonies compared to diluent control cultures, indicating a potential to pass the genetic damage to daughter cells. Our results demonstrate significant disruption of the mitotic spindle by MWCNT at occupationally relevant exposure levels. PMID:24479647

An estimate of the U.S. government's undercount of nonfatal occupational injuries and illnesses in agriculture.

PubMed

Leigh, J Paul; Du, Juan; McCurdy, Stephen A

2014-04-01

Debate surrounds the accuracy of U.S. government's estimates of job-related injuries and illnesses in agriculture. Whereas studies have attempted to estimate the undercount for all industries combined, none have specifically addressed agriculture. Data were drawn from the U.S. government's premier sources for workplace injuries and illnesses and employment: the Bureau of Labor Statistics databanks for the Survey of Occupational Injuries and Illnesses (SOII), the Quarterly Census of Employment and Wages, and the Current Population Survey. Estimates were constructed using transparent assumptions; for example, that the rate (cases-per-employee) of injuries and illnesses on small farms was the same as on large farms (an assumption we altered in sensitivity analysis). We estimated 74,932 injuries and illnesses for crop farms and 68,504 for animal farms, totaling 143,436 cases in 2011. We estimated that SOII missed 73.7% of crop farm cases and 81.9% of animal farm cases for an average of 77.6% for all agriculture. Sensitivity analyses suggested that the percent missed ranged from 61.5% to 88.3% for all agriculture. We estimate considerable undercounting of nonfatal injuries and illnesses in agriculture and believe the undercounting is larger than any other industry. Reasons include: SOII's explicit exclusion of employees on small farms and of farmers and family members and Quarterly Census of Employment and Wages's undercounts of employment. Undercounting limits our ability to identify and address occupational health problems in agriculture, affecting both workers and society. Copyright © 2014 Elsevier Inc. All rights reserved.

Occupancy models to study wildlife

USGS Publications Warehouse

Bailey, Larissa; Adams, Michael John

2005-01-01

Many wildlife studies seek to understand changes or differences in the proportion of sites occupied by a species of interest. These studies are hampered by imperfect detection of these species, which can result in some sites appearing to be unoccupied that are actually occupied. Occupancy models solve this problem and produce unbiased estimates of occupancy and related parameters. Required data (detection/non-detection information) are relatively simple and inexpensive to collect. Software is available free of charge to aid investigators in occupancy estimation.

Estimations of the lethal and exposure doses for representative methanol symptoms in humans.

PubMed

Moon, Chan-Seok

2017-01-01

The aim of this review was to estimate the lethal and exposure doses of a representative symptom (blindness) of methanol exposure in humans by reviewing data from previous articles. Available articles published from 1970 to 2016 that investigated the dose-response relationship for methanol exposure (i.e., the exposure concentration and the biological markers/clinical symptoms) were evaluated; the MEDLINE and RISS (Korean search engine) databases were searched. The available data from these articles were carefully selected to estimate the range and median of a lethal human dose. The regression equation and correlation coefficient (between the exposure level and urinary methanol concentration as a biological exposure marker) were assumed from the previous data. The lethal human dose of pure methanol was estimated at 15.8-474 g/person as a range and as 56.2 g/person as the median. The dose-response relationship between methanol vapor in ambient air and urinary methanol concentrations was thought to be correlated. An oral intake of 3.16-11.85 g/person of pure methanol could cause blindness. The lethal dose from respiratory intake was reported to be 4000-13,000 mg/l. The initial concentration of optic neuritis and blindness were shown to be 228.5 and 1103 mg/l, respectively, for a 12-h exposure. The concentration of biological exposure indices and clinical symptoms for methanol exposure might have a dose-response relationship according to previous articles. Even a low dose of pure methanol through oral or respiratory exposure might be lethal or result in blindness as a clinical symptom.

Adenosine 2A receptor occupancy by tozadenant and preladenant in rhesus monkeys.

PubMed

Barret, Olivier; Hannestad, Jonas; Alagille, David; Vala, Christine; Tavares, Adriana; Papin, Caroline; Morley, Thomas; Fowles, Krista; Lee, Hsiaoju; Seibyl, John; Tytgat, Dominique; Laruelle, Marc; Tamagnan, Gilles

2014-10-01

Motor symptoms in Parkinson disease (PD) are caused by a loss of dopamine input from the substantia nigra to the striatum. Blockade of adenosine 2A (A(2A)) receptors facilitates dopamine D(2) receptor function. In phase 2 clinical trials, A(2A) antagonists (istradefylline, preladenant, and tozadenant) improved motor function in PD. We developed a new A(2A) PET radiotracer, (18)F-MNI-444, and used it to investigate the relationship between plasma levels and A(2A) occupancy by preladenant and tozadenant in nonhuman primates (NHP). A series of 20 PET experiments was conducted in 5 adult rhesus macaques. PET data were analyzed with both plasma-input (Logan graphical analysis) and reference-region-based (simplified reference tissue model and noninvasive Logan graphical analysis) methods. Whole-body PET images were acquired for radiation dosimetry estimates. Human pharmacokinetic parameters for tozadenant and preladenant were used to predict A(2A) occupancy in humans, based on median effective concentration (EC(50)) values estimated from the NHP PET measurements. (18)F-MNI-444 regional uptake was consistent with A(2A) receptor distribution in the brain. Selectivity was demonstrated by dose-dependent blocking by tozadenant and preladenant. The specific-to-nonspecific ratio was superior to that of other A(2A) PET radiotracers. Pharmacokinetic modeling predicted that tozadenant and preladenant may have different profiles of A(2A) receptor occupancy in humans. (18)F-MNI-444 appears to be a better PET radiotracer for A(2A) imaging than currently available radiotracers. Assuming that EC(50) in humans is similar to that in NHP, it appears that tozadenant will provide a more sustained A(2A) receptor occupancy than preladenant in humans at clinically tested doses. © 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Small field depth dose profile of 6 MV photon beam in a simple air-water heterogeneity combination: A comparison between anisotropic analytical algorithm dose estimation with thermoluminescent dosimeter dose measurement.

PubMed

Mandal, Abhijit; Ram, Chhape; Mourya, Ankur; Singh, Navin

2017-01-01

To establish trends of estimation error of dose calculation by anisotropic analytical algorithm (AAA) with respect to dose measured by thermoluminescent dosimeters (TLDs) in air-water heterogeneity for small field size photon. TLDs were irradiated along the central axis of the photon beam in four different solid water phantom geometries using three small field size single beams. The depth dose profiles were estimated using AAA calculation model for each field sizes. The estimated and measured depth dose profiles were compared. The over estimation (OE) within air cavity were dependent on field size (f) and distance (x) from solid water-air interface and formulated as OE = - (0.63 f + 9.40) x2+ (-2.73 f + 58.11) x + (0.06 f2 - 1.42 f + 15.67). In postcavity adjacent point and distal points from the interface have dependence on field size (f) and equations are OE = 0.42 f2 - 8.17 f + 71.63, OE = 0.84 f2 - 1.56 f + 17.57, respectively. The trend of estimation error of AAA dose calculation algorithm with respect to measured value have been formulated throughout the radiation path length along the central axis of 6 MV photon beam in air-water heterogeneity combination for small field size photon beam generated from a 6 MV linear accelerator.

Prospective estimation of organ dose in CT under tube current modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Xiaoyu, E-mail: xt3@duke.edu; Li, Xiang; Segars, W. Paul

Purpose: Computed tomography (CT) has been widely used worldwide as a tool for medical diagnosis and imaging. However, despite its significant clinical benefits, CT radiation dose at the population level has become a subject of public attention and concern. In this light, optimizing radiation dose has become a core responsibility for the CT community. As a fundamental step to manage and optimize dose, it may be beneficial to have accurate and prospective knowledge about the radiation dose for an individual patient. In this study, the authors developed a framework to prospectively estimate organ dose for chest and abdominopelvic CT examsmore » under tube current modulation (TCM). Methods: The organ dose is mainly dependent on two key factors: patient anatomy and irradiation field. A prediction process was developed to accurately model both factors. To model the anatomical diversity and complexity in the patient population, the authors used a previously developed library of computational phantoms with broad distributions of sizes, ages, and genders. A selected clinical patient, represented by a computational phantom in the study, was optimally matched with another computational phantom in the library to obtain a representation of the patient’s anatomy. To model the irradiation field, a previously validated Monte Carlo program was used to model CT scanner systems. The tube current profiles were modeled using a ray-tracing program as previously reported that theoretically emulated the variability of modulation profiles from major CT machine manufacturers Li et al., [Phys. Med. Biol. 59, 4525–4548 (2014)]. The prediction of organ dose was achieved using the following process: (1) CTDI{sub vol}-normalized-organ dose coefficients (h{sub organ}) for fixed tube current were first estimated as the prediction basis for the computational phantoms; (2) each computation phantom, regarded as a clinical patient, was optimally matched with one computational phantom in the

Estimation of eye lens doses received by pediatric interventional cardiologists.

PubMed

Alejo, L; Koren, C; Ferrer, C; Corredoira, E; Serrada, A

2015-09-01

Maximum Hp(0.07) dose to the eye lens received in a year by the pediatric interventional cardiologists has been estimated. Optically stimulated luminescence dosimeters were placed on the eyes of an anthropomorphic phantom, whose position in the room simulates the most common irradiation conditions. Maximum workload was considered with data collected from procedures performed in the Hospital. None of the maximum values obtained exceed the dose limit of 20 mSv recommended by ICRP. Copyright © 2015 Elsevier Ltd. All rights reserved.

The economic burden of lung cancer and mesothelioma due to occupational and para-occupational asbestos exposure

PubMed Central

Tompa, Emile; Kalcevich, Christina; McLeod, Chris; Lebeau, Martin; Song, Chaojie; McLeod, Kim; Kim, Joanne; Demers, Paul A

2017-01-01

Objectives To estimate the economic burden of lung cancer and mesothelioma due to occupational and para-occupational asbestos exposure in Canada. Methods We estimate the lifetime cost of newly diagnosed lung cancer and mesothelioma cases associated with occupational and para-occupational asbestos exposure for calendar year 2011 based on the societal perspective. The key cost components considered are healthcare costs, productivity and output costs, and quality of life costs. Results There were 427 cases of newly diagnosed mesothelioma cases and 1904 lung cancer cases attributable to asbestos exposure in 2011 for a total of 2331 cases. Our estimate of the economic burden is $C831 million in direct and indirect costs for newly identified cases of mesothelioma and lung cancer and $C1.5 billion in quality of life costs based on a value of $C100 000 per quality-adjusted life year. This amounts to $C356 429 and $C652 369 per case, respectively. Conclusions The economic burden of lung cancer and mesothelioma associated with occupational and para-occupational asbestos exposure is substantial. The estimate identified is for 2331 newly diagnosed, occupational and para-occupational exposure cases in 2011, so it is only a portion of the burden of existing cases in that year. Our findings provide important information for policy decision makers for priority setting, in particular the merits of banning the mining of asbestos and use of products containing asbestos in countries where they are still allowed and also the merits of asbestos removal in older buildings with asbestos insulation. PMID:28756416

Global trend according to estimated number of occupational accidents and fatal work-related diseases at region and country level.

PubMed

Hämäläinen, Päivi; Leena Saarela, Kaija; Takala, Jukka

2009-01-01

Although occupational accidents and work-related diseases have been of interest for a long time, due to lack of proper recording and notification systems the official numbers of occupational accidents and work-related diseases are missing for many countries. Presently, the demand for effectiveness and an interest in the economic aspects of accidents have increased prevention activities at company and country levels. Occupational accident data of selected countries and of World Health Organization regional divisions together with the global burden of disease were used in estimating global occupational accidents and fatal work-related diseases. The trend of global occupational accidents and work-related diseases is presented at region and country levels. The years 1998, 2001, and 2003 are compared in the case of occupational accidents and the years 2000 and 2002 in the case of work-related diseases. The total number of occupational accidents and fatal work-related diseases has increased, but the fatality rates per 100,000 workers have decreased. There were almost 360,000 fatal occupational accidents in 2003 and almost 2 million fatal work-related diseases in 2002. Every day more than 960,000 workers get hurt because of accidents. Each day 5,330 people die because of work-related diseases. Information on occupational accidents and work-related diseases is needed so that countries may understand better the importance of occupational health and safety at country and company level. Especially companies in developing countries are not familiar with occupational safety and health. Statistical data is essential for accident prevention; it is a starting point for the safety work.

Dupuytren's contracture and occupational exposure to hand-transmitted vibration

PubMed Central

Palmer, Keith T; D'Angelo, Stefania; Syddall, Holly; Griffin, Michael J; Cooper, Cyrus; Coggon, David

2014-01-01

Aims The relation between Dupuytren's contracture and occupational exposure to hand-transmitted vibration (HTV) has frequently been debated. We explored associations in a representative national sample of workers with well-characterised exposure to HTV. Methods We mailed a questionnaire to 21 201 subjects aged 16–64 years, selected at random from the age-sex registers of 34 general practices in Great Britain and to 993 subjects chosen randomly from military pay records, asking about occupational exposure to 39 sources of HTV and about fixed flexion contracture of the little or ring finger. Analysis was restricted to men at work in the previous week. Estimates were made of average daily vibration dose (A(8) root mean squared velocity (rms)) over that week. Associations with Dupuytren's contracture were estimated by Poisson regression, for lifetime exposure to HTV and for exposures in the past week >A(8) of 2.8 ms−2 rms. Estimates of relative risk (prevalence ratio (PR)) were adjusted for age, smoking status, social class and certain manual activities at work. Results In all 4969 eligible male respondents supplied full information on the study variables. These included 72 men with Dupuytren's contracture, 2287 with occupational exposure to HTV and 409 with A(8)>2.8 ms−2 in the past week. PRs for occupational exposure to HTV were elevated 1.5-fold. For men with an A(8)>2.8 ms−2 in the past week, the adjusted PR was 2.85 (95% CI 1.37 to 5.97). Conclusions Our findings suggest that risk of Dupuytren's contracture is more than doubled in men with high levels of weekly exposure to HTV. PMID:24449599

Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John's wort: an [11C]-harmine PET study.

PubMed

Sacher, Julia; Houle, Sylvain; Parkes, Jun; Rusjan, Pablo; Sagrati, Sandra; Wilson, Alan A; Meyer, Jeffrey H

2011-11-01

Monoamine oxidase A (MAO-A) inhibitor antidepressants raise levels of multiple monoamines, whereas the selective serotonin reuptake inhibitors (SSRIs) only raise extracellular serotonin. Despite this advantage of MAO-A inhibitors, there is much less frequent development of MAO inhibitors compared with SSRIs. We sought to measure brain MAO-A occupancy after 6 weeks of treatment in depressed patients with a clinically effective dose of a selective MAO-A inhibitor and measure MAO-A occupancy after repeated administration of St. John's wort, an herb purported to have MAO-A inhibitor properties. Participants underwent 2 [(11)C]-harmine positron emission tomography scans. Healthy controls completed a test-retest condition, and depressed patients were scanned before and after repeated administration of moclobemide or St. John's wort for 6 weeks at the assigned dose. We measured MAO-A VT, an index of MAO-A density, in the prefrontal, anterior cingulate and anterior temporal cortices, putamen, thalamus, midbrain and hippocampus. We included 23 participants (10 controls and 13 patients with major depressive disorder [MDD]) in our study. Monoamine oxidase A VT decreased significantly throughout all regions after moclobemide treatment in patients with MDD compared with controls (repeated-measures analysis of variance, F1,15 = 71.08-130.06, p < 0.001 for all regions, mean occupancy 74% [standard deviation 6%]). Treatment with St. John's wort did not significantly alter MAO-A VT. The occupancy estimates are limited by the sample size of each treatment group; hence, our estimate for the overall moclobemide occupancy of 74% has a 95% confidence interval of 70%-78%, and we can estimate with 95% certainty that the occupancy of St. John's wort is less than 5%. For new MAO-A inhibitors, about 74% occupancy at steady-state dosing is desirable. Consistent with this, St. John's wort should not be classified as an MAO-A inhibitor. The magnitude of MAO-A blockade during moclobemide

[Estimation of Maximum Entrance Skin Dose during Cerebral Angiography].

PubMed

Kawauchi, Satoru; Moritake, Takashi; Hayakawa, Mikito; Hamada, Yusuke; Sakuma, Hideyuki; Yoda, Shogo; Satoh, Masayuki; Sun, Lue; Koguchi, Yasuhiro; Akahane, Keiichi; Chida, Koichi; Matsumaru, Yuji

2015-09-01

Using radio-photoluminescence glass dosimeter, we measured the entrance skin dose (ESD) in 46 cases and analyzed the correlations between maximum ESD and angiographic parameters [total fluoroscopic time (TFT); number of digital subtraction angiography (DSA) frames, air kerma at the interventional reference point (AK), and dose-area product (DAP)] to estimate the maximum ESD in real time. Mean (± standard deviation) maximum ESD, dose of the right lens, and dose of the left lens were 431.2 ± 135.8 mGy, 33.6 ± 15.5 mGy, and 58.5 ± 35.0 mGy, respectively. Correlation coefficients (r) between maximum ESD and TFT, number of DSA frames, AK, and DAP were r=0.379 (P<0.01), r=0.702 (P<0.001), r=0.825 (P<0.001), and r=0.709 (P<0.001), respectively. AK was identified as the most useful parameter for real-time prediction of maximum ESD. This study should contribute to the development of new diagnostic reference levels in our country.

A comprehensive dose reconstruction methodology for former rocketdyne/atomics international radiation workers.

PubMed

Boice, John D; Leggett, Richard W; Ellis, Elizabeth Dupree; Wallace, Phillip W; Mumma, Michael; Cohen, Sarah S; Brill, A Bertrand; Chadda, Bandana; Boecker, Bruce B; Yoder, R Craig; Eckerman, Keith F

2006-05-01

Incomplete radiation exposure histories, inadequate treatment of internally deposited radionuclides, and failure to account for neutron exposures can be important uncertainties in epidemiologic studies of radiation workers. Organ-specific doses from lifetime occupational exposures and radionuclide intakes were estimated for an epidemiologic study of 5,801 Rocketdyne/Atomics International (AI) radiation workers engaged in nuclear technologies between 1948 and 1999. The entire workforce of 46,970 Rocketdyne/AI employees was identified from 35,042 Kardex work histories cards, 26,136 electronic personnel listings, and 14,189 radiation folders containing individual exposure histories. To obtain prior and subsequent occupational exposure information, the roster of all workers was matched against nationwide dosimetry files from the Department of Energy, the Nuclear Regulatory Commission, the Landauer dosimetry company, the U.S. Army, and the U.S. Air Force. Dosimetry files of other worker studies were also accessed. Computation of organ doses from radionuclide intakes was complicated by the diversity of bioassay data collected over a 40-y period (urine and fecal samples, lung counts, whole-body counts, nasal smears, and wound and incident reports) and the variety of radionuclides with documented intake including isotopes of uranium, plutonium, americium, calcium, cesium, cerium, zirconium, thorium, polonium, promethium, iodine, zinc, strontium, and hydrogen (tritium). Over 30,000 individual bioassay measurements, recorded on 11 different bioassay forms, were abstracted. The bioassay data were evaluated using ICRP biokinetic models recommended in current or upcoming ICRP documents (modified for one inhaled material to reflect site-specific information) to estimate annual doses for 16 organs or tissues taking into account time of exposure, type of radionuclide, and excretion patterns. Detailed internal exposure scenarios were developed and annual internal doses were derived

Occupational exposures to antineoplastic drugs and ionizing radiation in Canadian veterinary settings: findings from a national surveillance project.

PubMed

Hall, Amy L; Davies, Hugh W; Demers, Paul A; Nicol, Anne-Marie; Peters, Cheryl E

2013-11-01

Although veterinary workers may encounter various occupational health hazards, a national characterization of exposures is lacking in Canada. This study used secondary data sources to identify veterinary exposure prevalence for ionizing radiation and antineoplastic agents, as part of a national surveillance project. For ionizing radiation, data from the Radiation Protection Bureau of Health Canada were used to identify veterinarians and veterinary technicians monitored in 2006. This was combined with Census statistics to estimate a prevalence range and dose levels. For antineoplastic agents, exposure prevalence was estimated using statistics on employment by practice type and antineoplastic agent usage rates, obtained from veterinary licensing bodies and peer-reviewed literature. In 2006, 7,013 (37% of all) Canadian veterinary workers were monitored for ionizing radiation exposure. An estimated 3.3% to 8.2% of all veterinarians and 2.4% to 7.2% of veterinary technicians were exposed to an annual ionizing radiation dose above 0.1 mSv, representing a total of between 536 and 1,450 workers. All monitored doses were below regulatory limits. For antineoplastic agents, exposure was predicted in up to 5,300 (23%) of all veterinary workers, with an estimated prevalence range of 22% to 24% of veterinarians and 20% to 21% of veterinary technicians. This is the first national-level assessment of exposure to ionizing radiation and antineoplastic agents in Canadian veterinary settings. These hazards may pose considerable health risks. Exposures appeared to be low, however our estimates should be validated with comprehensive exposure monitoring and examination of determinants across practice areas, occupations, and tasks.

Estimating occupational illness, injury, and mortality in food production in the United States: A farm-to-table analysis

PubMed Central

Leon, Juan S.; Newman, Lee S.

2015-01-01

Objectives The study provides a novel model and more comprehensive estimates of the burden of occupational morbidity and mortality in food-related industries, using a farm-to-table approach. Methods The authors analyzed 2008–2010 US Bureau of Labor Statistics data for private industries in the different stages of the farm-to-table model (production; processing; distribution and storage; retail and preparation). Results The morbidity rate for food system industries were significantly higher than the morbidity rate for non-food system industries (Rate Ratio (RR)=1.62, 95% Confidence Interval (CI): 1.30–2.01). Furthermore, the occupational mortality rate for food system industries was significantly higher than the national non-food occupational mortality rate (RR=9.51, 95% CI: 2.47–36.58). Conclusions This is the first use of the farm-to-table model to assess occupational morbidity and mortality, and these findings highlighting specific workplace hazards across food system industries. PMID:25970031

Military Participants at U.S. Atmospheric Nuclear Weapons Testing— Methodology for Estimating Dose and Uncertainty

PubMed Central

Till, John E.; Beck, Harold L.; Aanenson, Jill W.; Grogan, Helen A.; Mohler, H. Justin; Mohler, S. Shawn; Voillequé, Paul G.

2014-01-01

Methods were developed to calculate individual estimates of exposure and dose with associated uncertainties for a sub-cohort (1,857) of 115,329 military veterans who participated in at least one of seven series of atmospheric nuclear weapons tests or the TRINITY shot carried out by the United States. The tests were conducted at the Pacific Proving Grounds and the Nevada Test Site. Dose estimates to specific organs will be used in an epidemiological study to investigate leukemia and male breast cancer. Previous doses had been estimated for the purpose of compensation and were generally high-sided to favor the veteran's claim for compensation in accordance with public law. Recent efforts by the U.S. Department of Defense (DOD) to digitize the historical records supporting the veterans’ compensation assessments make it possible to calculate doses and associated uncertainties. Our approach builds upon available film badge dosimetry and other measurement data recorded at the time of the tests and incorporates detailed scenarios of exposure for each veteran based on personal, unit, and other available historical records. Film badge results were available for approximately 25% of the individuals, and these results assisted greatly in reconstructing doses to unbadged persons and in developing distributions of dose among military units. This article presents the methodology developed to estimate doses for selected cancer cases and a 1% random sample of the total cohort of veterans under study. PMID:24758578

[An investigation of ionizing radiation dose in a manufacturing enterprise of ion-absorbing type rare earth ore].

PubMed

Zhang, W F; Tang, S H; Tan, Q; Liu, Y M

2016-08-20

Objective: To investigate radioactive source term dose monitoring and estimation results in a manufacturing enterprise of ion-absorbing type rare earth ore and the possible ionizing radiation dose received by its workers. Methods: Ionizing radiation monitoring data of the posts in the control area and supervised area of workplace were collected, and the annual average effective dose directly estimated or estimated using formulas was evaluated and analyzed. Results: In the control area and supervised area of the workplace for this rare earth ore, α surface contamination activity had a maximum value of 0.35 Bq/cm 2 and a minimum value of 0.01 Bq/cm 2 ; β radioactive surface contamination activity had a maximum value of 18.8 Bq/cm 2 and a minimum value of 0.22 Bq/cm 2 . In 14 monitoring points in the workplace, the maximum value of the annual average effective dose of occupational exposure was 1.641 mSv/a, which did not exceed the authorized limit for workers (5 mSv/a) , but exceeded the authorized limit for general personnel (0.25 mSv/a) . The radionuclide specific activity of ionic mixed rare earth oxides was determined to be 0.9. Conclusion: The annual average effective dose of occupational exposure in this enterprise does not exceed the authorized limit for workers, but it exceeds the authorized limit for general personnel. We should pay attention to the focus of the radiation process, especially for public works radiation.

Estimation of Occupational Test Norms from Job Analysis Data.

ERIC Educational Resources Information Center

Mecham, Robert C.

Occupational norms exist for some tests, and differences in the distributions of test scores by occupation are evident. Sampling error (SE), situationally specific factors (SSFs), and differences in job content (DIJCs) were explored as possible reasons for the observed differences. SE was explored by analyzing 742 validity studies performed by the…

Estimation of the total effective dose from low-dose CT scans and radiopharmaceutical administrations delivered to patients undergoing SPECT/CT explorations.

PubMed

Montes, Carlos; Tamayo, Pilar; Hernandez, Jorge; Gomez-Caminero, Felipe; García, Sofia; Martín, Carlos; Rosero, Angela

2013-08-01

Hybrid imaging, such as SPECT/CT, is used in routine clinical practice, allowing coregistered images of the functional and structural information provided by the two imaging modalities. However, this multimodality imaging may mean that patients are exposed to a higher radiation dose than those receiving SPECT alone. The study aimed to determine the radiation exposure of patients who had undergone SPECT/CT examinations and to relate this to the Background Equivalent Radiation Time (BERT). 145 SPECT/CT studies were used to estimate the total effective dose to patients due to both radiopharmaceutical administrations and low-dose CT scans. The CT contribution was estimated by the Dose-Length Product method. Specific conversion coefficients were calculated for SPECT explorations. The radiation dose from low-dose CTs ranged between 0.6 mSv for head and neck CT and 2.6 mSv for whole body CT scan, representing a maximum of 1 year of background radiation exposure. These values represent a decrease of 80-85% with respect to the radiation dose from diagnostic CT. The radiation exposure from radiopharmaceutical administration varied from 2.1 mSv for stress myocardial perfusion SPECT to 26 mSv for gallium SPECT in patients with lymphoma. The BERT ranged from 1 to 11 years. The contribution of low-dose CT scans to the total radiation dose to patients undergoing SPECT/CT examinations is relatively low compared with the effective dose from radiopharmaceutical administration. When a CT scan is only acquired for anatomical localization and attenuation correction, low-dose CT scan is justified on the basis of its lower dose.

Dose rate estimation of the Tohoku hynobiid salamander, Hynobius lichenatus, in Fukushima.

PubMed

Fuma, Shoichi; Ihara, Sadao; Kawaguchi, Isao; Ishikawa, Takahiro; Watanabe, Yoshito; Kubota, Yoshihisa; Sato, Youji; Takahashi, Hiroyuki; Aono, Tatsuo; Ishii, Nobuyoshi; Soeda, Haruhi; Matsui, Kumi; Une, Yumi; Minamiya, Yukio; Yoshida, Satoshi

2015-05-01

The radiological risks to the Tohoku hynobiid salamanders (class Amphibia), Hynobius lichenatus due to the Fukushima Dai-ichi Nuclear Power Plant accident were assessed in Fukushima Prefecture, including evacuation areas. Aquatic egg clutches (n = 1 for each sampling date and site; n = 4 in total), overwintering larvae (n = 1-5 for each sampling date and site; n = 17 in total), and terrestrial juveniles or adults (n = 1 or 3 for each sampling date and site; n = 12 in total) of H. lichenatus were collected from the end of April 2011 to April 2013. Environmental media such as litter (n = 1-5 for each sampling date and site; n = 30 in total), soil (n = 1-8 for each sampling date and site; n = 31 in total), water (n = 1 for each sampling date and site; n = 17 in total), and sediment (n = 1 for each sampling date and site; n = 17 in total) were also collected. Activity concentrations of (134)Cs + (137)Cs were 1.9-2800, 0.13-320, and 0.51-220 kBq (dry kg) (-1) in the litter, soil, and sediment samples, respectively, and were 0.31-220 and <0.29-40 kBq (wet kg)(-1) in the adult and larval salamanders, respectively. External and internal absorbed dose rates to H. lichenatus were calculated from these activity concentration data, using the ERICA Assessment Tool methodology. External dose rates were also measured in situ with glass dosimeters. There was agreement within a factor of 2 between the calculated and measured external dose rates. In the most severely contaminated habitat of this salamander, a northern part of Abukuma Mountains, the highest total dose rates were estimated to be 50 and 15 μGy h(-1) for the adults and overwintering larvae, respectively. Growth and survival of H. lichenatus was not affected at a dose rate of up to 490 μGy h(-1) in the previous laboratory chronic gamma-irradiation experiment, and thus growth and survival of this salamander would not be affected, even in the most severely contaminated habitat in Fukushima Prefecture. However, further

Estimation of parameters of dose volume models and their confidence limits

NASA Astrophysics Data System (ADS)

van Luijk, P.; Delvigne, T. C.; Schilstra, C.; Schippers, J. M.

2003-07-01

Predictions of the normal-tissue complication probability (NTCP) for the ranking of treatment plans are based on fits of dose-volume models to clinical and/or experimental data. In the literature several different fit methods are used. In this work frequently used methods and techniques to fit NTCP models to dose response data for establishing dose-volume effects, are discussed. The techniques are tested for their usability with dose-volume data and NTCP models. Different methods to estimate the confidence intervals of the model parameters are part of this study. From a critical-volume (CV) model with biologically realistic parameters a primary dataset was generated, serving as the reference for this study and describable by the NTCP model. The CV model was fitted to this dataset. From the resulting parameters and the CV model, 1000 secondary datasets were generated by Monte Carlo simulation. All secondary datasets were fitted to obtain 1000 parameter sets of the CV model. Thus the 'real' spread in fit results due to statistical spreading in the data is obtained and has been compared with estimates of the confidence intervals obtained by different methods applied to the primary dataset. The confidence limits of the parameters of one dataset were estimated using the methods, employing the covariance matrix, the jackknife method and directly from the likelihood landscape. These results were compared with the spread of the parameters, obtained from the secondary parameter sets. For the estimation of confidence intervals on NTCP predictions, three methods were tested. Firstly, propagation of errors using the covariance matrix was used. Secondly, the meaning of the width of a bundle of curves that resulted from parameters that were within the one standard deviation region in the likelihood space was investigated. Thirdly, many parameter sets and their likelihood were used to create a likelihood-weighted probability distribution of the NTCP. It is concluded that for the

Fatality reduction by safety belts for front-seat occupants of cars and light trucks : updated and expanded estimates based on 1986-99 FARS data

DOT National Transportation Integrated Search

2000-12-01

The National Highway Traffic Safety Administration estimated in 1984 that manual 3-point safety belts : reduce the fatality risk of front-seat occupants of passenger cars by 45 percent relative to the unrestrained : occupant. The agency still relies ...

Estimation of dose-response models for discrete and continuous data in weed science

USDA-ARS?s Scientific Manuscript database

Dose-response analysis is widely used in biological sciences and has application to a variety of risk assessment, bioassay, and calibration problems. In weed science, dose-response methodologies have typically relied on least squares estimation under an assumption of normality. Advances in computati...

Occupation and cancer in Britain

PubMed Central

Rushton, L; Bagga, S; Bevan, R; Brown, T P; Cherrie, J W; Holmes, P; Fortunato, L; Slack, R; Van Tongeren, M; Young, C; Hutchings, S J

2010-01-01

Background: Prioritising control measures for occupationally related cancers should be evidence based. We estimated the current burden of cancer in Britain attributable to past occupational exposures for International Agency for Research on Cancer (IARC) group 1 (established) and 2A (probable) carcinogens. Methods: We calculated attributable fractions and numbers for cancer mortality and incidence using risk estimates from the literature and national data sources to estimate proportions exposed. Results: 5.3% (8019) cancer deaths were attributable to occupation in 2005 (men, 8.2% (6362); women, 2.3% (1657)). Attributable incidence estimates are 13 679 (4.0%) cancer registrations (men, 10 063 (5.7%); women, 3616 (2.2%)). Occupational attributable fractions are over 2% for mesothelioma, sinonasal, lung, nasopharynx, breast, non-melanoma skin cancer, bladder, oesophagus, soft tissue sarcoma, larynx and stomach cancers. Asbestos, shift work, mineral oils, solar radiation, silica, diesel engine exhaust, coal tars and pitches, occupation as a painter or welder, dioxins, environmental tobacco smoke, radon, tetrachloroethylene, arsenic and strong inorganic mists each contribute 100 or more registrations. Industries and occupations with high cancer registrations include construction, metal working, personal and household services, mining, land transport, printing/publishing, retail/hotels/restaurants, public administration/defence, farming and several manufacturing sectors. 56% of cancer registrations in men are attributable to work in the construction industry (mainly mesotheliomas, lung, stomach, bladder and non-melanoma skin cancers) and 54% of cancer registrations in women are attributable to shift work (breast cancer). Conclusion: This project is the first to quantify in detail the burden of cancer and mortality due to occupation specifically for Britain. It highlights the impact of occupational exposures, together with the occupational circumstances and industrial

Occupation and cancer in Britain.

PubMed

Rushton, L; Bagga, S; Bevan, R; Brown, T P; Cherrie, J W; Holmes, P; Fortunato, L; Slack, R; Van Tongeren, M; Young, C; Hutchings, S J

2010-04-27

Prioritising control measures for occupationally related cancers should be evidence based. We estimated the current burden of cancer in Britain attributable to past occupational exposures for International Agency for Research on Cancer (IARC) group 1 (established) and 2A (probable) carcinogens. We calculated attributable fractions and numbers for cancer mortality and incidence using risk estimates from the literature and national data sources to estimate proportions exposed. 5.3% (8019) cancer deaths were attributable to occupation in 2005 (men, 8.2% (6362); women, 2.3% (1657)). Attributable incidence estimates are 13 679 (4.0%) cancer registrations (men, 10 063 (5.7%); women, 3616 (2.2%)). Occupational attributable fractions are over 2% for mesothelioma, sinonasal, lung, nasopharynx, breast, non-melanoma skin cancer, bladder, oesophagus, soft tissue sarcoma, larynx and stomach cancers. Asbestos, shift work, mineral oils, solar radiation, silica, diesel engine exhaust, coal tars and pitches, occupation as a painter or welder, dioxins, environmental tobacco smoke, radon, tetrachloroethylene, arsenic and strong inorganic mists each contribute 100 or more registrations. Industries and occupations with high cancer registrations include construction, metal working, personal and household services, mining, land transport, printing/publishing, retail/hotels/restaurants, public administration/defence, farming and several manufacturing sectors. 56% of cancer registrations in men are attributable to work in the construction industry (mainly mesotheliomas, lung, stomach, bladder and non-melanoma skin cancers) and 54% of cancer registrations in women are attributable to shift work (breast cancer). This project is the first to quantify in detail the burden of cancer and mortality due to occupation specifically for Britain. It highlights the impact of occupational exposures, together with the occupational circumstances and industrial areas where exposures to carcinogenic agents

Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John’s wort: an [11C]-harmine PET study

PubMed Central

Sacher, Julia; Houle, Sylvain; Parkes, Jun; Rusjan, Pablo; Sagrati, Sandra; Wilson, Alan A.; Meyer, Jeffrey H.

2011-01-01

Background Monoamine oxidase A (MAO-A) inhibitor antidepressants raise levels of multiple monoamines, whereas the selective serotonin reuptake inhibitors (SSRIs) only raise extracellular serotonin. Despite this advantage of MAO-A inhibitors, there is much less frequent development of MAO inhibitors compared with SSRIs. We sought to measure brain MAO-A occupancy after 6 weeks of treatment in depressed patients with a clinically effective dose of a selective MAO-A inhibitor and measure MAO-A occupancy after repeated administration of St. John’s wort, an herb purported to have MAO-A inhibitor properties. Methods Participants underwent 2 [11C]-harmine positron emission tomography scans. Healthy controls completed a test–retest condition, and depressed patients were scanned before and after repeated administration of moclobemide or St. John’s wort for 6 weeks at the assigned dose. We measured MAO-A VT, an index of MAO-A density, in the prefrontal, anterior cingulate and anterior temporal cortices, putamen, thalamus, midbrain and hippocampus. Results We included 23 participants (10 controls and 13 patients with major depressive disorder [MDD]) in our study. Monoamine oxidase A VT decreased significantly throughout all regions after moclobemide treatment in patients with MDD compared with controls (repeated-measures analysis of variance, F1,15 = 71.08–130.06, p < 0.001 for all regions, mean occupancy 74% [standard deviation 6%]). Treatment with St. John’s wort did not significantly alter MAO-A VT. Limitations The occupancy estimates are limited by the sample size of each treatment group; hence, our estimate for the overall moclobemide occupancy of 74% has a 95% confidence interval of 70%–78%, and we can estimate with 95% certainty that the occupancy of St. John’s wort is less than 5%. Conclusion For new MAO-A inhibitors, about 74% occupancy at steady-state dosing is desirable. Consistent with this, St. John’s wort should not be classified as an MAO

In-flight measured and predicted ambient dose equivalent and latitude differences on effective dose estimates.

PubMed

Saez Vergara, J C; Romero Gutiérrez, A M; Rodriguez Jiménez, R; Dominguez-Mompell Román, R

2004-01-01

The results from 2 years (2001-2002) of experimental measurements of in-board radiation doses received at IBERIA commercial flights are presented. The routes studied cover the most significant destinations and provide a good estimate of the route doses as required by the new Spanish regulations on air crew radiation protection. Details on the experimental procedures and calibration methods are given. The experimental measurements from the different instruments (Tissue Equivalent Proportional Counter and the combination of a high pressure ion chamber and a high-energy neutron compensated rem-counter) and their comparison with the predictions from some route-dose codes (CARI-6, EPCARD 3.2) are discussed. In contrast with the already published data, which are mainly focused on North latitudes over parallel 50, many of the data presented in this work have been obtained for routes from Spain to Central and South America.

Asthma caused by occupational exposures is common – A systematic analysis of estimates of the population-attributable fraction

PubMed Central

Torén, Kjell; Blanc, Paul D

2009-01-01

Background The aim of this paper is to highlight emerging data on occupational attributable risk in asthma. Despite well documented outbreaks of disease and the recognition of numerous specific causal agents, occupational exposures previously had been relegated a fairly minor role relative to other causes of adult onset asthma. In recent years there has been a growing recognition of the potential importance of asthma induced by work-related exposures Methods We searched Pub Med from June 1999 through December 2007. We identified six longitudinal general population-based studies; three case-control studies and eight cross-sectional analyses from seven general population-based samples. For an integrated analysis we added ten estimates prior to 1999 included in a previous review. Results The longitudinal studies indicate that 16.3% of all adult-onset asthma is caused by occupational exposures. In an overall synthesis of all included studies the overall median PAR value was 17.6%. Conclusion Clinicians should consider the occupational history when evaluating patients in working age who have asthma. At a societal level, these findings underscore the need for further preventive action to reduce the occupational exposures to asthma-causing agents. PMID:19178702

Occupational seafood allergy: a review

PubMed Central

Jeebhay, M; Robins, T; Lehrer, S; Lopata, A

2001-01-01

BACKGROUND—Recent years have seen increased levels of production and consumption of seafood, leading to more frequent reporting of allergic reactions in occupational and domestic settings. This review focuses on occupational allergy in the fishing and seafood processing industry.
REVIEW—Workers involved in either manual or automated processing of crabs, prawns, mussels, fish, and fishmeal production are commonly exposed to various constituents of seafood. Aerosolisation of seafood and cooking fluid during processing are potential occupational situations that could result in sensitisation through inhalation. There is great variability of aerosol exposure within and among various jobs with reported allergen concentrations ranging from 0.001 to 5.061(µg/m3). Occupational dermal exposure occurs as a result of unprotected handling of seafood and its byproducts. Occupational allergies have been reported in workers exposed to arthropods (crustaceans), molluscs, pisces (bony fish) and other agents derived from seafood. The prevalence of occupational asthma ranges from 7% to 36%, and for occupational protein contact dermatitis, from 3% to 11%. These health outcomes are mainly due to high molecular weight proteins in seafood causing an IgE mediated response. Cross reactivity between various species within a major seafood grouping also occurs. Limited evidence from dose-response relations indicate that development of symptoms is related to duration or intensity of exposure. The evidence for atopy as a risk factor for occupational sensitisation and asthma is supportive, whereas evidence for cigarette smoking is limited. Disruption of the intact skin barrier seems to be an important added risk factor for occupational protein contact dermatitis.
CONCLUSION—The range of allergic disease associated with occupational exposure to crab is well characterised, whereas for other seafood agents the evidence is somewhat limited. There is a need for further epidemiological

Estimating Upper Bounds for Occupancy and Number of Manatees in Areas Potentially Affected by Oil from the Deepwater Horizon Oil Spill

PubMed Central

Martin, Julien; Edwards, Holly H.; Bled, Florent; Fonnesbeck, Christopher J.; Dupuis, Jérôme A.; Gardner, Beth; Koslovsky, Stacie M.; Aven, Allen M.; Ward-Geiger, Leslie I.; Carmichael, Ruth H.; Fagan, Daniel E.; Ross, Monica A.; Reinert, Thomas R.

2014-01-01

The explosion of the Deepwater Horizon drilling platform created the largest marine oil spill in U.S. history. As part of the Natural Resource Damage Assessment process, we applied an innovative modeling approach to obtain upper estimates for occupancy and for number of manatees in areas potentially affected by the oil spill. Our data consisted of aerial survey counts in waters of the Florida Panhandle, Alabama and Mississippi. Our method, which uses a Bayesian approach, allows for the propagation of uncertainty associated with estimates from empirical data and from the published literature. We illustrate that it is possible to derive estimates of occupancy rate and upper estimates of the number of manatees present at the time of sampling, even when no manatees were observed in our sampled plots during surveys. We estimated that fewer than 2.4% of potentially affected manatee habitat in our Florida study area may have been occupied by manatees. The upper estimate for the number of manatees present in potentially impacted areas (within our study area) was estimated with our model to be 74 (95%CI 46 to 107). This upper estimate for the number of manatees was conditioned on the upper 95%CI value of the occupancy rate. In other words, based on our estimates, it is highly probable that there were 107 or fewer manatees in our study area during the time of our surveys. Because our analyses apply to habitats considered likely manatee habitats, our inference is restricted to these sites and to the time frame of our surveys. Given that manatees may be hard to see during aerial surveys, it was important to account for imperfect detection. The approach that we described can be useful for determining the best allocation of resources for monitoring and conservation. PMID:24670971

Occupational dose constraints for the lens of the eye for interventional radiologists and interventional cardiologists in the UK.

PubMed

Mairs, William DA

2016-06-01

The International Commission on Radiological Protection (ICRP) has recommended a 20 mSv year(-1) dose limit for the lens of the eye, which has been adopted in the European Union Basic Safety Standards. Interventional radiologists (IRs) and interventional cardiologists (ICs) are likely to be affected by this. The effects of radiation in the lens are somewhat uncertain, and the ICRP explicitly recommend optimization. Occupational dose constraints are part of the optimization process and define a level of dose which ought to be achievable in a well-managed practice. This commentary calls on the professional bodies to review a need for national constraints to guide local decisions. Consideration is given to developing such constraints using maximum expected doses in high-workload facilities with good radiation protection practices and application of a factor allowing for attenuation by lead glasses (LG). Doses are based on a Public Health England survey of eye dose in the UK. Maximum expected doses for ICs are approximately 21 mSv year(-1), neglecting LG. However, the extent of IR exposure is not yet fully known, and further evidence is required before conclusions are drawn. A Health and Safety Laboratory review of LG established a conservative dose reduction factor of 3 for models available in 2012. Application of this factor provides a dose constraint of 7 mSv year(-1) to the eye for ICs. To achieve this constraint, those employers with the most exposed ICs will have to provide and ensure the correct use of a ceiling-suspended eye shield and LG.

Estimating site occupancy, colonization, and local extinction when a species is detected imperfectly

USGS Publications Warehouse

MacKenzie, D.I.; Nichols, J.D.; Hines, J.E.; Knutson, M.G.; Franklin, A.B.

2003-01-01

Few species are likely to be so evident that they will always be detected when present. Failing to allow for the possibility that a target species was present, but undetected, at a site will lead to biased estimates of site occupancy, colonization, and local extinction probabilities. These population vital rates are often of interest in long-term monitoring programs and metapopulation studies. We present a model that enables direct estimation of these parameters when the probability of detecting the species is less than 1. The model does not require any assumptions of process stationarity, as do some previous methods, but does require detection/nondetection data to be collected in a manner similar to Pollock's robust design as used in mark?recapture studies. Via simulation, we show that the model provides good estimates of parameters for most scenarios considered. We illustrate the method with data from monitoring programs of Northern Spotted Owls (Strix occidentalis caurina) in northern California and tiger salamanders (Ambystoma tigrinum) in Minnesota, USA.

Estimating site occupancy, colonization, and local extinction when a species is detected imperfectly

USGS Publications Warehouse

MacKenzie, D.I.; Nichols, J.D.; Hines, J.E.; Knutson, M.G.; Franklin, A.B.

2003-01-01

Few species are likely to be so evident that they will always be defected when present: Failing to allow for the possibility that a target species was present, but undetected at a site will lead to biased estimates of site occupancy, colonization,and local extinction probabilities. These population vital rates are often of interest in long-term monitoring programs and metapopulation studies. We present a model that enables direct estimation of these parameters when the probability of detecting the species is less than 1. The model does not require any assumptions-of process stationarity, as do some previous methods, but does require detection/nondetection data to be collected in a-manner similar to. Pollock's robust design as used-in mark-recapture studies. Via simulation, we,show that the model provides good estimates of parameters for most scenarios considered. We illustrate the method with data from monitoring programs of Northern Spotted Owls (Strix occidentalis caurina) in northern California and tiger salamanders (Ambystoma tigrinum) in Minnesota, USA.

Estimation of Effective Dose from External Exposure in The Six Prefectures adjacent to Fukushima Prefecture

NASA Astrophysics Data System (ADS)

Miyatake, Hirokazu; Yoshizawa, Nobuaki; Hirakawa, Sachiko; Murakami, Kana; Takizawa, Mari; Kawai, Masaki; Sato, Osamu; Takagi, Shunji; Suzuki, Gen

2017-09-01

The Fukushima Daiichi Nuclear Power Plant accident caused a release of radionuclides. Radionuclides were deposited on the ground not only in Fukushima prefecture but also in nearby prefectures. Since the accident, measurement of radiation in environment such as air dose rate and deposition density of radionuclides has been performed by many organizations and universities. In particular, Japan Atomic Energy Agency (JAEA) has been performing observations of air dose rate using a car-borne survey system continuously and over wide areas. In our study, using the data measured by JAEA, we estimated effective dose from external exposure in the six prefectures adjacent to Fukushima prefecture. Since car-borne survey was started a few months later after the accident, measured air dose rate in this method is mainly contributed by 137Cs and 134Cs whose half-lives are relatively long. Therefore, based on air dose rate of 137Cs and 134Cs and the ratio of deposition density of short-half-life nuclides to that of 137Cs and 134Cs, we also estimated effective dose contributed from not only 137Cs and 134Cs but also other short-half-life nuclides. We compared the effective dose estimated by the method above with that of UNSCEAR and measured data using personal dosimeters in some areas.

Supplemental computational phantoms to estimate out-of-field absorbed dose in photon radiotherapy

NASA Astrophysics Data System (ADS)

Gallagher, Kyle J.; Tannous, Jaad; Nabha, Racile; Feghali, Joelle Ann; Ayoub, Zeina; Jalbout, Wassim; Youssef, Bassem; Taddei, Phillip J.

2018-01-01

The purpose of this study was to develop a straightforward method of supplementing patient anatomy and estimating out-of-field absorbed dose for a cohort of pediatric radiotherapy patients with limited recorded anatomy. A cohort of nine children, aged 2-14 years, who received 3D conformal radiotherapy for low-grade localized brain tumors (LBTs), were randomly selected for this study. The extent of these patients’ computed tomography simulation image sets were cranial only. To approximate their missing anatomy, we supplemented the LBT patients’ image sets with computed tomography images of patients in a previous study with larger extents of matched sex, height, and mass and for whom contours of organs at risk for radiogenic cancer had already been delineated. Rigid fusion was performed between the LBT patients’ data and that of the supplemental computational phantoms using commercial software and in-house codes. In-field dose was calculated with a clinically commissioned treatment planning system, and out-of-field dose was estimated with a previously developed analytical model that was re-fit with parameters based on new measurements for intracranial radiotherapy. Mean doses greater than 1 Gy were found in the red bone marrow, remainder, thyroid, and skin of the patients in this study. Mean organ doses between 150 mGy and 1 Gy were observed in the breast tissue of the girls and lungs of all patients. Distant organs, i.e. prostate, bladder, uterus, and colon, received mean organ doses less than 150 mGy. The mean organ doses of the younger, smaller LBT patients (0-4 years old) were a factor of 2.4 greater than those of the older, larger patients (8-12 years old). Our findings demonstrated the feasibility of a straightforward method of applying supplemental computational phantoms and dose-calculation models to estimate absorbed dose for a set of children of various ages who received radiotherapy and for whom anatomies were largely missing in their original

ESTIMATION OF EXPOSURE DOSES FOR THE SAFE MANAGEMENT OF NORM WASTE DISPOSAL.

PubMed

Jeong, Jongtae; Ko, Nak Yul; Cho, Dong-Keun; Baik, Min Hoon; Yoon, Ki-Hoon

2018-03-16

Naturally occurring radioactive materials (NORM) wastes with different radiological characteristics are generated in several industries. The appropriate options for NORM waste management including disposal options should be discussed and established based on the act and regulation guidelines. Several studies calculated the exposure dose and mass of NORM waste to be disposed in landfill site by considering the activity concentration level and exposure dose. In 2012, the Korean government promulgated an act on the safety control of NORM around living environments to protect human health and the environment. For the successful implementation of this act, we suggest a reference design for a landfill for the disposal of NORM waste. Based on this reference landfill, we estimate the maximum exposure doses and the relative impact of each pathway to exposure dose for three scenarios: a reference scenario, an ingestion pathway exclusion scenario, and a low leach rate scenario. Also, we estimate the possible quantity of NORM waste disposal into a landfill as a function of the activity concentration level of U series, Th series and 40K and two kinds of exposure dose levels, 1 and 0.3 mSv/y. The results of this study can be used to support the establishment of technical bases of the management strategy for the safe disposal of NORM waste.

Comparison of Measured and Estimated CT Organ Doses for Modulated and Fixed Tube Current:: A Human Cadaver Study.

PubMed

Padole, Atul; Deedar Ali Khawaja, Ranish; Otrakji, Alexi; Zhang, Da; Liu, Bob; Xu, X George; Kalra, Mannudeep K

2016-05-01

The aim of this study was to compare the directly measured and the estimated computed tomography (CT) organ doses obtained from commercial radiation dose-tracking (RDT) software for CT performed with modulated tube current or automatic exposure control (AEC) technique and fixed tube current (mAs). With the institutional review board (IRB) approval, the ionization chambers were surgically implanted in a human cadaver (88 years old, male, 68 kg) in six locations such as liver, stomach, colon, left kidney, small intestine, and urinary bladder. The cadaver was scanned with routine abdomen pelvis protocol on a 128-slice, dual-source multidetector computed tomography (MDCT) scanner using both AEC and fixed mAs. The effective and quality reference mAs of 100, 200, and 300 were used for AEC and fixed mAs, respectively. Scanning was repeated three times for each setting, and measured and estimated organ doses (from RDT software) were recorded (N = 3*3*2 = 18). Mean CTDIvol for AEC and fixed mAs were 4, 8, 13 mGy and 7, 14, 21 mGy, respectively. The most estimated organ doses were significantly greater (P < 0.01) than the measured organ doses for both AEC and fixed mAs. At AEC, the mean estimated organ doses (for six organs) were 14.7 mGy compared to mean measured organ doses of 12.3 mGy. Similarly, at fixed mAs, the mean estimated organ doses (for six organs) were 24 mGy compared to measured organ doses of 22.3 mGy. The differences among the measured and estimated organ doses were higher for AEC technique compared to the fixed mAs for most organs (P < 0.01). The most CT organ doses estimated from RDT software are greater compared to directly measured organ doses, particularly when AEC technique is used for CT scanning. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

A framework for organ dose estimation in x-ray angiography and interventional radiology based on dose-related data in DICOM structured reports

NASA Astrophysics Data System (ADS)

Omar, Artur; Bujila, Robert; Fransson, Annette; Andreo, Pedro; Poludniowski, Gavin

2016-04-01

Although interventional x-ray angiography (XA) procedures involve relatively high radiation doses that can lead to deterministic tissue reactions in addition to stochastic effects, convenient and accurate estimation of absorbed organ doses has traditionally been out of reach. This has mainly been due to the absence of practical means to access dose-related data that describe the physical context of the numerous exposures during an XA procedure. The present work provides a comprehensive and general framework for the determination of absorbed organ dose, based on non-proprietary access to dose-related data by utilizing widely available DICOM radiation dose structured reports. The framework comprises a straightforward calculation workflow to determine the incident kerma and reconstruction of the geometrical relation between the projected x-ray beam and the patient’s anatomy. The latter is difficult in practice, as the position of the patient on the table top is unknown. A novel patient-specific approach for reconstruction of the patient position on the table is presented. The proposed approach was evaluated for 150 patients by comparing the estimated position of the primary irradiated organs (the target organs) with their position in clinical DICOM images. The approach is shown to locate the target organ position with a mean (max) deviation of 1.3 (4.3), 1.8 (3.6) and 1.4 (2.9) cm for neurovascular, adult and paediatric cardiovascular procedures, respectively. To illustrate the utility of the framework for systematic and automated organ dose estimation in routine clinical practice, a prototype implementation of the framework with Monte Carlo simulations is included.

Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT.

PubMed

Paul, Jijo; Banckwitz, Rosemarie; Krauss, Bernhard; Vogl, Thomas J; Maentele, Werner; Bauer, Ralf W

2012-04-01

To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation. Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120kV, (2) single-source 100kV, (3) high-pitch 120kV, and (4) dual-energy with 100/Sn140kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived. DLP-based estimates differed by 4.5-16.56% and 5.2-15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04mSv. Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04mSv. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The economic burden of lung cancer and mesothelioma due to occupational and para-occupational asbestos exposure.

PubMed

Tompa, Emile; Kalcevich, Christina; McLeod, Chris; Lebeau, Martin; Song, Chaojie; McLeod, Kim; Kim, Joanne; Demers, Paul A

2017-11-01

To estimate the economic burden of lung cancer and mesothelioma due to occupational and para-occupational asbestos exposure in Canada. We estimate the lifetime cost of newly diagnosed lung cancer and mesothelioma cases associated with occupational and para-occupational asbestos exposure for calendar year 2011 based on the societal perspective. The key cost components considered are healthcare costs, productivity and output costs, and quality of life costs. There were 427 cases of newly diagnosed mesothelioma cases and 1904 lung cancer cases attributable to asbestos exposure in 2011 for a total of 2331 cases. Our estimate of the economic burden is $C831 million in direct and indirect costs for newly identified cases of mesothelioma and lung cancer and $C1.5 billion in quality of life costs based on a value of $C100 000 per quality-adjusted life year. This amounts to $C356 429 and $C652 369 per case, respectively. The economic burden of lung cancer and mesothelioma associated with occupational and para-occupational asbestos exposure is substantial. The estimate identified is for 2331 newly diagnosed, occupational and para-occupational exposure cases in 2011, so it is only a portion of the burden of existing cases in that year. Our findings provide important information for policy decision makers for priority setting, in particular the merits of banning the mining of asbestos and use of products containing asbestos in countries where they are still allowed and also the merits of asbestos removal in older buildings with asbestos insulation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Dose estimation to eye lens of industrial gamma radiography workers using the Monte Carlo method.

PubMed

de Lima, Alexandre Roza; Hunt, John Graham; Da Silva, Francisco Cesar Augusto

2017-12-01

The ICRP Statement on Tissue Reactions (2011), based on epidemiological evidence, recommended a reduction for the eye lens equivalent dose limit from 150 to 20 mSv per year. This paper presents mainly the dose estimations received by industrial gamma radiography workers, during planned or accidental exposure to the eye lens, Hp(10) and effective dose. A Brazilian Visual Monte Carlo Dose Calculation program was used and two relevant scenarios were considered. For the planned exposure situation, twelve radiographic exposures per day for 250 days per year, which leads to a direct exposure of 10 h per year, were considered. The simulation was carried out using a 192 Ir source with 1.0 TBq of activity; a source/operator distance between 5 and 10 m and placed at heights of 0.02 m, 1 m and 2 m, and an exposure time of 12 s. Using a standard height of 1 m, the eye lens doses were estimated as being between 16.3 and 60.3 mGy per year. For the accidental exposure situation, the same radionuclide and activity were used, but in this case the doses were calculated with and without a collimator. The heights above ground considered were 1.0 m, 1.5 m and 2.0 m; the source/operator distance was 40 cm, and the exposure time 74 s. The eye lens doses at 1.5 m were 12.3 and 0.28 mGy without and with a collimator, respectively. The conclusions were that: (1) the estimated doses show that the 20 mSv annual limit for eye lens equivalent dose can directly impact industrial gamma radiography activities, mainly in industries with high number of radiographic exposures per year; (2) the risk of lens opacity has a low probability for a single accident, but depending on the number of accidental exposures and the dose levels found in planned exposures, the threshold dose can easily be exceeded during the professional career of an industrial radiography operator, and; (3) in a first approximation, Hp(10) can be used to estimate the equivalent dose to the eye lens.

Occupational fatalities in Jordan.

PubMed

Al-Abdallat, Emad M; Oqailan, Ahmad Mohammad A; Al Ali, Rayyan; Hudaib, Arwa A; Salameh, Ghada A M

2015-01-01

Occupational fatalities are a worldwide problem. Certain occupations pose a greater risk than others. Recent statistics on global occupational injuries and diseases that might lead to temporary or permanent disability and even worse might lead to death, are staggering. The purpose of this study was to estimate the death rates from occupational injuries in Jordan over a period of four years; to estimate occupational fatality rate that results from accidental injuries and identify the most risky concurrent occupations with the type of injuries, the age and nationality of the victims. A total of 88 work related fatalities were admitted to three hospitals in Amman through 2008-2012 and were examined by a forensic (occupational) physician at the time. They were categorized according to, age, nationality, occupation, type of injury and were all tested for toxic substances. The occupation with the most fatalities was construction (44%); falling from a height was the commonest type of accident (44%) and head injuries were the leading injury type (21.6%); 9.1% of the deaths were positive for alcohol. Moreover, 22.7% of deaths were between ages of 25-29. Consequently, the mean occupational fatality rate was 2 per 100.000 workers during 2008-2012. Constructions and other types of occupations are more extensive problems than what is usually anticipated, especially when safety precautions are not effective or implemented. They may cause injuries and death, which will have a socioeconomic burden on families, society, governments and industries. Not to mention the grief that is associated with the death of a worker at his work site to all concerned parties. Copyright © 2014 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Occupational Choice: A Conditional Logit Model with Special Reference to Wage Subsidies and Occupational Choice. Final Report.

ERIC Educational Resources Information Center

Boskin, Michael J.

A model of occupational choice based on the theory of human capital is developed and estimated by conditional logit analysis. The empirical results estimated the probability of individuals with certain characteristics (such as race, sex, age, and education) entering each of 11 occupational groups. The results indicate that individuals tend to…

[Fatal occupational accidents: estimates based on more data sources].

PubMed

Baldasseroni, A; Chellini, E; Zoppi, O; Giovannetti, L

2001-01-01

The data reported by INAIL (Istituto Nazionale Assicurazione Infortuni sul Lavoro) on fatal occupational injuries have always been considered complete and reliable. The authors of this article verified the completeness of this information source crossing it with data bases existing in different registration systems (Regional Mortality Registry of Tuscany--RMR; registers and data of the Operative Units of Prevention, Hygiene and Safety in the Workplace--UOPISLL) for the period between 1992 and 1996. In the five years concerned, a total of 458 cases were reported. These cases could be considered fatal injuries at work without taking into account traffic accidents, which were not included in the present study. The results show that the most complete information source was RMR, reporting 80% of the total data, while INAIL reports only 62.2% of the total cases. On the contrary, the UOPISLL source is the least reliable. Using the capture/recapture method, the estimate of events in the period concerned (1992-1996) amounts to nearly 500 (499.8 LC 475.9-523.7), while the three sources systematically explored for the whole period (INAIL, RMR, UOSPILL) report 458 cases. An additional information source, the daily press, which could be systematically tested only two months for each of the five years, reports 10 additional cases, which were ignored by the 3 other sources, indirectly confirming in this way how reliable the performed estimate was. The main cases among the 157 fatal accidents reported by RMR, but not by INAIL, occurred among farmers (70), most of them already retired, but there were several fatal accidents reported in the construction sector (30). Other categories were included only in the RMR data because, in the period concerned, they were not covered by INAIL insurance (18 cases in the Army and Police, 7 on the railways). The survey that was carried out confirms the essential importance of INAIL data for the surveillance system applied to this phenomenon. This

Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

PubMed Central

Li, Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Toncheva, Greta; Yoshizumi, Terry T.; Frush, Donald P.

2011-01-01

Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient’s clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDIvol) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller patients

PET measurement of receptor occupancy as a tool to guide dose selection in neuropharmacology: are we asking the right questions?

PubMed

Barrett, Jeffrey S; McGuire, Jennifer; Vezina, Heather; Spitsin, Serguei; Douglas, Steven D

2013-12-01

Receptor occupancy studies are becoming commonplace for verifying drug mechanism of action and selecting early development candidates. Positron emission tomography (PET) has been applied to pharmacodynamic (PD) studies in several therapeutic areas including neurology, cardiology, and oncology. Prospective use of PET to define dosing requirements has been proposed particularly for central nervous system (CNS)-targeted drugs; however, correlations with clinical outcomes have been mostly anecdotal and not causally established.

Occupational cancer in Britain. Preventing occupational cancer.

PubMed

Chen, Yiqun; Osman, John

2012-06-19

Although only a relatively small proportion of cancer is attributable to occupational exposure to carcinogenic agents, the estimated number of deaths due to occupational cancer is high when compared to other deaths due to work-related ill health and injury. However, risk from occupational exposure to carcinogens can be minimised through proportionate but effective risk management. The Health and Safety Executive (HSE) is the regulator of workplace health and safety in Great Britain. As part of its aim to reduce ill health arising from failures to control properly exposure to hazards at work, HSE commissioned the research presented elsewhere in this supplement to enable it to identify priorities for preventing occupational cancer. The research has shown that occupational cancer remains a key health issue and that low-level exposure of a large number of workers to carcinogens is important. The finding that a small number of carcinogens have been responsible for the majority of the burden of occupational cancer provides key evidence in the development of priorities for significant reduction of occupational cancer. Although the research presented in this supplement reflects the consequences of past exposures to carcinogens, occupational cancer remains a problem. The potential for exposure to the agents considered in this research is still present in the workplace and the findings are relevant to prevention of future disease. In this article, the principle approaches for risk reduction are described. It provides supporting information on some of the initiatives already being undertaken, or those being put in place, to reduce occupational cancer in Great Britain. The need also for systematic collection of exposure information and the importance of raising awareness and changing behaviours are discussed.

Risk of injury for occupants of motor vehicle collisions from unbelted occupants.

PubMed

MacLennan, P A; McGwin, G; Metzger, J; Moran, S G; Rue, L W

2004-12-01

Unbelted occupants may increase the risk of injury for other occupants in a motor vehicle collision (MVC). This study evaluated the association between occupant restraint use and the risk of injury (including death) to other vehicle occupants. A population based cohort study. United States. MVC occupants (n = 152 191 unweighted, n = 18 426 684 weighted) seated between a belted or unbelted occupant and the line of the principal direction of force in frontal, lateral, and rear MVCs were sampled from the 1991-2002 National Automotive Sampling System General Estimates System. Offset MVCs were not included in the study. Risk ratios and 95% confidence intervals for injury (including death) for occupants seated contiguous to unbelted occupants compared to occupants seated contiguous to belted occupants. Risk ratios were adjusted for at risk occupant's sex, age, seating position, vehicle type, collision type, travel speed, crash severity, and at risk occupants' own seat belt use. Exposure to unbelted occupants was associated with a 40% increased risk of any injury. Belted at risk occupants were at a 90% increased risk of injury but unbelted occupants were not at increased risk. Risks were similar for non-incapacitating and capacitating injuries. There was a 4.8-fold increased risk of death for exposed belted occupants but no increased risk of death for unbelted occupants. Belted occupants are at an increased risk of injury and death in the event of a MVC from unbelted occupants.

Methodologies for the quantitative estimation of toxicant dose to cigarette smokers using physical, chemical and bioanalytical data.

PubMed

St Charles, Frank Kelley; McAughey, John; Shepperd, Christopher J

2013-06-01

Methodologies have been developed, described and demonstrated that convert mouth exposure estimates of cigarette smoke constituents to dose by accounting for smoke spilled from the mouth prior to inhalation (mouth-spill (MS)) and the respiratory retention (RR) during the inhalation cycle. The methodologies are applicable to just about any chemical compound in cigarette smoke that can be measured analytically and can be used with ambulatory population studies. Conversion of exposure to dose improves the relevancy for risk assessment paradigms. Except for urinary nicotine plus metabolites, biomarkers generally do not provide quantitative exposure or dose estimates. In addition, many smoke constituents have no reliable biomarkers. We describe methods to estimate the RR of chemical compounds in smoke based on their vapor pressure (VP) and to estimate the MS for a given subject. Data from two clinical studies were used to demonstrate dose estimation for 13 compounds, of which only 3 have urinary biomarkers. Compounds with VP > 10(-5) Pa generally have RRs of 88% or greater, which do not vary appreciably with inhalation volume (IV). Compounds with VP < 10(-7) Pa generally have RRs dependent on IV and lung exposure time. For MS, mean subject values from both studies were slightly greater than 30%. For constituents with urinary biomarkers, correlations with the calculated dose were significantly improved over correlations with mouth exposure. Of toxicological importance is that the dose correlations provide an estimate of the metabolic conversion of a constituent to its respective biomarker.

Performance of species occurrence estimators when basic assumptions are not met: a test using field data where true occupancy status is known

USGS Publications Warehouse

Miller, David A. W.; Bailey, Larissa L.; Grant, Evan H. Campbell; McClintock, Brett T.; Weir, Linda A.; Simons, Theodore R.

2015-01-01

Our results demonstrate that even small probabilities of misidentification and among-site detection heterogeneity can have severe effects on estimator reliability if ignored. We challenge researchers to place greater attention on both heterogeneity and false positives when designing and analysing occupancy studies. We provide 9 specific recommendations for the design, implementation and analysis of occupancy studies to better meet this challenge.

Study of the Phototransference in GR-200 Dosimetric Material and its Convenience for Dose Re-estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baly, L.; Otazo, M. R.; Molina, D.

2006-09-08

A study of the phototransference of charges from deep to dosimetric traps in GR-200 material is presented and its convenience for dose re-estimation in the dose range between 2 and 100mSv is also analyzed. The recovering coefficient (RC) defined as the ratio between the phototransferred thermoluminescence (PTTL) and the original thermoluminescence (TL) of the dosimetric trap was used to evaluate the ratio of phototransferred charges from deep traps and the original charges in the dosimetric traps. The results show the convenience of this method for dose re-estimation for this material in the selected range of doses.

Phantom-derived estimation of effective dose equivalent from X rays with and without a lead apron.

PubMed

Mateya, C F; Claycamp, H G

1997-06-01

Organ dose equivalents were measured in a humanoid phantom in order to estimate effective dose equivalent (H(E)) and effective dose (E) from low-energy x rays and in the presence or absence of a protective lead apron. Plane-parallel irradiation conditions were approximated using direct x-ray beams of 76 and 104 kVp and resulting dosimetry data was adjusted to model exposures conditions in fluoroscopy settings. Values of H(E) and E estimated under-shielded conditions were compared to the results of several recent studies that used combinations of measured and calculated dosimetry to model exposures to radiologists. While the estimates of H(E) and E without the lead apron were within 0.2 to 20% of expected values, estimates based on personal monitors worn at the (phantom) waist (underneath the apron) underestimated either H(E) or E while monitors placed at the neck (above the apron) significantly overestimated both quantities. Also, the experimentally determined H(E) and E were 1.4 to 3.3 times greater than might be estimated using recently reported "two-monitor" algorithms for the estimation of effective dose quantities. The results suggest that accurate estimation of either H(E) or E from personal monitors under conditions of partial body exposures remains problematic and is likely to require the use of multiple monitors.

A method of estimating conceptus doses resulting from multidetector CT examinations during all stages of gestation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Damilakis, John; Tzedakis, Antonis; Perisinakis, Kostas

Purpose: Current methods for the estimation of conceptus dose from multidetector CT (MDCT) examinations performed on the mother provide dose data for typical protocols with a fixed scan length. However, modified low-dose imaging protocols are frequently used during pregnancy. The purpose of the current study was to develop a method for the estimation of conceptus dose from any MDCT examination of the trunk performed during all stages of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study to model the Siemens Sensation 16 and Sensation 64 MDCT scanners. Four mathematical phantoms were used, simulatingmore » women at 0, 3, 6, and 9 months of gestation. The contribution to the conceptus dose from single simulated scans was obtained at various positions across the phantoms. To investigate the effect of maternal body size and conceptus depth on conceptus dose, phantoms of different sizes were produced by adding layers of adipose tissue around the trunk of the mathematical phantoms. To verify MCNP results, conceptus dose measurements were carried out by means of three physical anthropomorphic phantoms, simulating pregnancy at 0, 3, and 6 months of gestation and thermoluminescence dosimetry (TLD) crystals. Results: The results consist of Monte Carlo-generated normalized conceptus dose coefficients for single scans across the four mathematical phantoms. These coefficients were defined as the conceptus dose contribution from a single scan divided by the CTDI free-in-air measured with identical scanning parameters. Data have been produced to take into account the effect of maternal body size and conceptus position variations on conceptus dose. Conceptus doses measured with TLD crystals showed a difference of up to 19% compared to those estimated by mathematical simulations. Conclusions: Estimation of conceptus doses from MDCT examinations of the trunk performed on pregnant patients during all stages of gestation can be

Designing occupancy studies when false-positive detections occur

USGS Publications Warehouse

Clement, Matthew

2016-01-01

1.Recently, estimators have been developed to estimate occupancy probabilities when false-positive detections occur during presence-absence surveys. Some of these estimators combine different types of survey data to improve estimates of occupancy. With these estimators, there is a tradeoff between the number of sample units surveyed, and the number and type of surveys at each sample unit. Guidance on efficient design of studies when false positives occur is unavailable. 2.For a range of scenarios, I identified survey designs that minimized the mean square error of the estimate of occupancy. I considered an approach that uses one survey method and two observation states and an approach that uses two survey methods. For each approach, I used numerical methods to identify optimal survey designs when model assumptions were met and parameter values were correctly anticipated, when parameter values were not correctly anticipated, and when the assumption of no unmodelled detection heterogeneity was violated. 3.Under the approach with two observation states, false positive detections increased the number of recommended surveys, relative to standard occupancy models. If parameter values could not be anticipated, pessimism about detection probabilities avoided poor designs. Detection heterogeneity could require more or fewer repeat surveys, depending on parameter values. If model assumptions were met, the approach with two survey methods was inefficient. However, with poor anticipation of parameter values, with detection heterogeneity, or with removal sampling schemes, combining two survey methods could improve estimates of occupancy. 4.Ignoring false positives can yield biased parameter estimates, yet false positives greatly complicate the design of occupancy studies. Specific guidance for major types of false-positive occupancy models, and for two assumption violations common in field data, can conserve survey resources. This guidance can be used to design efficient

Modeling estimates of the effect of acid rain on background radiation dose.

PubMed Central

Sheppard, S C; Sheppard, M I

1988-01-01

Acid rain causes accelerated mobilization of many materials in soils. Natural and anthropogenic radionuclides, especially 226Ra and 137Cs, are among these materials. Okamoto is apparently the only researcher to date who has attempted to quantify the effect of acid rain on the "background" radiation dose to man. He estimated an increase in dose by a factor of 1.3 following a decrease in soil pH of 1 unit. We reviewed literature that described the effects of changes in pH on mobility and plant uptake of Ra and Cs. Generally, a decrease in soil pH by 1 unit will increase mobility and plant uptake by factors of 2 to 7. Thus, Okamoto's dose estimate may be too low. We applied several simulation models to confirm Okamoto's ideas, with most emphasis on an atmospherically driven soil model that predicts water and nuclide flow through a soil profile. We modeled a typical, acid-rain sensitive soil using meteorological data from Geraldton, Ontario. The results, within the range of effects on the soil expected from acidification, showed essentially direct proportionality between the mobility of the nuclides and dose. This supports some of the assumptions invoked by Okamoto. We conclude that a decrease in pH of 1 unit may increase the mobility of Ra and Cs by a factor of 2 or more. Our models predict that this will lead to similar increases in plant uptake and radiological dose to man. Although health effects following such a small increase in dose have not been statistically demonstrated, any increase in dose is probably undesirable. PMID:3203639

Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit

NASA Astrophysics Data System (ADS)

El-Jaby, Samy; Richardson, Richard B.

2015-07-01

Occupational exposures from ionizing radiation are currently regulated for airline travel (<20 km) and for missions to low-Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit.

Estimating Toxicity-Related Biological Pathway Altering Doses for High-Throughput Chemical Risk Assessment

EPA Science Inventory

We describe a framework for estimating the human dose at which a chemical significantly alters a biological pathway in vivo, making use of in vitro assay data and an in vitro derived pharmacokinetic model, coupled with estimates of population variability and uncertainty. The q...

The Effects of Metal on Size Specific Dose Estimation (SSDE) in CT: A Phantom Study

NASA Astrophysics Data System (ADS)

Alsanea, Maram M.

Over the past number of years there has been a significant increase in the awareness of radiation dose from use of computed tomography (CT). Efforts have been made to reduce radiation dose from CT and to better quantify dose being delivered. However, unfortunately, these dose metrics such as CTDI vol are not a specific patient dose. In 2011, the size-specific dose estimation (SSDE) was introduced by AAPM TG-204 which accounts for the physical size of the patient. However, the approach presented in TG-204 ignores the importance of the attenuation differences in the body. In 2014, a newer methodology that accounted for tissue attenuation was introduced by the AAPM TG-220 based on the concept of water equivalent diameter, Dw. One of the limitation of TG-220 is that there is no estimation of the dose while highly attenuating objects such as metal is present in the body. The purpose of this research is to evaluate the accuracy of size-specific dose estimates in CT in the presence of simulated metal prostheses using a conventional PMMA CTDI phantom at different phantom diameter (body and head) and beam energy. Titanium, Cobalt- chromium and stainless steel alloys rods were used in the study. Two approaches were used as introduced by AAPM TG-204 and 220 utilizing the effective diameter and the Dw calculations. From these calculations, conversion factors have been derived that could be applied to the measured CTDIvol to convert it to specific patient dose, or size specific dose estimate, (SSDE). Radiation dose in tissue (f-factor = 0.94) was measured at various chamber positions with the presence of metal. Following, an average weighted tissue dose (AWTD) was calculated in a manner similar to the weighted CTDI (CTDIw). In general, for the 32 cm body phantom SSDE220 provided more accurate estimates of AWTD than did SSDE204. For smaller patient size, represented by the 16 cm head phantom, the SSDE204 was a more accurate estimate of AWTD that that of SSDE220. However, as the

IDENTIFICATION OF OFF-FARM AGRICULTURAL OCCUPATIONS AND THE EDUCATION NEEDED FOR EMPLOYMENT IN THESE OCCUPATIONS IN DELAWARE.

ERIC Educational Resources Information Center

BARWICK, RALPH P.

THE PURPOSES OF THE STUDY WERE TO (1) IDENTIFY PRESENT AND EMERGING OFF-FARM AGRICULTURAL OCCUPATIONS, (2) ESTIMATE THE NUMBER EMPLOYED, (3) ESTIMATE THE NUMBER TO BE EMPLOYED IN THE FUTURE, AND (4) DETERMINE COMPETENCIES NEEDED IN SELECTED OCCUPATIONAL FAMILIES. A DISPROPORTIONATE RANDOM SAMPLE OF 267 BUSINESSES OR SERVICES WAS DRAWN FROM A LIST…

Comparison of measured and estimated maximum skin doses during CT fluoroscopy lung biopsies.

PubMed

Zanca, F; Jacobs, A; Crijns, W; De Wever, W

2014-07-01

To measure patient-specific maximum skin dose (MSD) associated with CT fluoroscopy (CTF) lung biopsies and to compare measured MSD with the MSD estimated from phantom measurements, as well as with the CTDIvol of patient examinations. Data from 50 patients with lung lesions who underwent a CT fluoroscopy-guided biopsy were collected. The CT protocol consisted of a low-kilovoltage (80 kV) protocol used in combination with an algorithm for dose reduction to the radiology staff during the interventional procedure, HandCare (HC). MSD was assessed during each intervention using EBT2 gafchromic films positioned on patient skin. Lesion size, position, total fluoroscopy time, and patient-effective diameter were registered for each patient. Dose rates were also estimated at the surface of a normal-size anthropomorphic thorax phantom using a 10 cm pencil ionization chamber placed at every 30°, for a full rotation, with and without HC. Measured MSD was compared with MSD values estimated from the phantom measurements and with the cumulative CTDIvol of the procedure. The median measured MSD was 141 mGy (range 38-410 mGy) while the median cumulative CTDIvol was 72 mGy (range 24-262 mGy). The ratio between the MSD estimated from phantom measurements and the measured MSD was 0.87 (range 0.12-4.1) on average. In 72% of cases the estimated MSD underestimated the measured MSD, while in 28% of the cases it overestimated it. The same trend was observed for the ratio of cumulative CTDIvol and measured MSD. No trend was observed as a function of patient size. On average, estimated MSD from dose rate measurements on phantom as well as from CTDIvol of patient examinations underestimates the measured value of MSD. This can be attributed to deviations of the patient's body habitus from the standard phantom size and to patient positioning in the gantry during the procedure.

Simple Method to Estimate Mean Heart Dose From Hodgkin Lymphoma Radiation Therapy According to Simulation X-Rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nimwegen, Frederika A. van; Cutter, David J.; Oxford Cancer Centre, Oxford University Hospitals NHS Trust, Oxford

Purpose: To describe a new method to estimate the mean heart dose for Hodgkin lymphoma patients treated several decades ago, using delineation of the heart on radiation therapy simulation X-rays. Mean heart dose is an important predictor for late cardiovascular complications after Hodgkin lymphoma (HL) treatment. For patients treated before the era of computed tomography (CT)-based radiotherapy planning, retrospective estimation of radiation dose to the heart can be labor intensive. Methods and Materials: Patients for whom cardiac radiation doses had previously been estimated by reconstruction of individual treatments on representative CT data sets were selected at random from a case–controlmore » study of 5-year Hodgkin lymphoma survivors (n=289). For 42 patients, cardiac contours were outlined on each patient's simulation X-ray by 4 different raters, and the mean heart dose was estimated as the percentage of the cardiac contour within the radiation field multiplied by the prescribed mediastinal dose and divided by a correction factor obtained by comparison with individual CT-based dosimetry. Results: According to the simulation X-ray method, the medians of the mean heart doses obtained from the cardiac contours outlined by the 4 raters were 30 Gy, 30 Gy, 31 Gy, and 31 Gy, respectively, following prescribed mediastinal doses of 25-42 Gy. The absolute-agreement intraclass correlation coefficient was 0.93 (95% confidence interval 0.85-0.97), indicating excellent agreement. Mean heart dose was 30.4 Gy with the simulation X-ray method, versus 30.2 Gy with the representative CT-based dosimetry, and the between-method absolute-agreement intraclass correlation coefficient was 0.87 (95% confidence interval 0.80-0.95), indicating good agreement between the two methods. Conclusion: Estimating mean heart dose from radiation therapy simulation X-rays is reproducible and fast, takes individual anatomy into account, and yields results comparable to the labor

Simple method to estimate mean heart dose from Hodgkin lymphoma radiation therapy according to simulation X-rays.

PubMed

van Nimwegen, Frederika A; Cutter, David J; Schaapveld, Michael; Rutten, Annemarieke; Kooijman, Karen; Krol, Augustinus D G; Janus, Cécile P M; Darby, Sarah C; van Leeuwen, Flora E; Aleman, Berthe M P

2015-05-01

To describe a new method to estimate the mean heart dose for Hodgkin lymphoma patients treated several decades ago, using delineation of the heart on radiation therapy simulation X-rays. Mean heart dose is an important predictor for late cardiovascular complications after Hodgkin lymphoma (HL) treatment. For patients treated before the era of computed tomography (CT)-based radiotherapy planning, retrospective estimation of radiation dose to the heart can be labor intensive. Patients for whom cardiac radiation doses had previously been estimated by reconstruction of individual treatments on representative CT data sets were selected at random from a case-control study of 5-year Hodgkin lymphoma survivors (n=289). For 42 patients, cardiac contours were outlined on each patient's simulation X-ray by 4 different raters, and the mean heart dose was estimated as the percentage of the cardiac contour within the radiation field multiplied by the prescribed mediastinal dose and divided by a correction factor obtained by comparison with individual CT-based dosimetry. According to the simulation X-ray method, the medians of the mean heart doses obtained from the cardiac contours outlined by the 4 raters were 30 Gy, 30 Gy, 31 Gy, and 31 Gy, respectively, following prescribed mediastinal doses of 25-42 Gy. The absolute-agreement intraclass correlation coefficient was 0.93 (95% confidence interval 0.85-0.97), indicating excellent agreement. Mean heart dose was 30.4 Gy with the simulation X-ray method, versus 30.2 Gy with the representative CT-based dosimetry, and the between-method absolute-agreement intraclass correlation coefficient was 0.87 (95% confidence interval 0.80-0.95), indicating good agreement between the two methods. Estimating mean heart dose from radiation therapy simulation X-rays is reproducible and fast, takes individual anatomy into account, and yields results comparable to the labor-intensive representative CT-based method. This simpler method may produce a

Occupational and patient exposure as well as image quality for full spine examinations with the EOS imaging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Damet, J., E-mail: jerome.damet@chuv.ch; Fournier, P.; Monnin, P.

Purpose: EOS (EOS imaging S.A, Paris, France) is an x-ray imaging system that uses slot-scanning technology in order to optimize the trade-off between image quality and dose. The goal of this study was to characterize the EOS system in terms of occupational exposure, organ doses to patients as well as image quality for full spine examinations. Methods: Occupational exposure was determined by measuring the ambient dose equivalents in the radiological room during a standard full spine examination. The patient dosimetry was performed using anthropomorphic phantoms representing an adolescent and a five-year-old child. The organ doses were measured with thermoluminescent detectorsmore » and then used to calculate effective doses. Patient exposure with EOS was then compared to dose levels reported for conventional radiological systems. Image quality was assessed in terms of spatial resolution and different noise contributions to evaluate the detector's performances of the system. The spatial-frequency signal transfer efficiency of the imaging system was quantified by the detective quantum efficiency (DQE). Results: The use of a protective apron when the medical staff or parents have to stand near to the cubicle in the radiological room is recommended. The estimated effective dose to patients undergoing a full spine examination with the EOS system was 290μSv for an adult and 200 μSv for a child. MTF and NPS are nonisotropic, with higher values in the scanning direction; they are in addition energy-dependent, but scanning speed independent. The system was shown to be quantum-limited, with a maximum DQE of 13%. The relevance of the DQE for slot-scanning system has been addressed. Conclusions: As a summary, the estimated effective dose was 290μSv for an adult; the image quality remains comparable to conventional systems.« less

[A procedure for estimating the rate of occupational accidents in non-European-Union workers with irregular immigrant status].

PubMed

Marchiori, L; Marangi, G; Mazzoccoli, P; Scoizzato, L; Buja, Alessandra; Mastrangelo, G

2008-01-01

Statistics on occupational accidents provided by the Italian Institute for Occupational Diseases and Accidents (INAIL, Italian acronym) include only events that occurred in workers with regular employment status. The aim of the study was to establish a procedure in order to estimate the rate of occupational accidents in non-European-Union (non-EU) workers with irregular employment status and/or irregular immigrant status. The sources of data were the clinical records of the Emergency Department of San Bonifacio Hospital, and the population data of District 4 of Local Health Authority 20 of Verona, which was considered the catchment area of this hospital. Among 419 cases of accidents occurred in the numerator of the rate. The denominator of the rate was estimated by calculating: (1) the subjects of working age resident in District 4 (= 83714); (2) the total number of non-EU workers, assuming that the percentage was similar to that in San Bonifacio Municipality (= 0.115); the number of irregular non-EU workers, assuming that the percentage was similar to that in north-eastern Italy (= 0.103). Non-EU workers with irregular employment status and/or irregular immigrant status should, according to these calculations, be 992 (= 83714 x 0.115 x 0.103). The rate--147.2 (= 146/992) occupational accidents per 1000 irregular non-EU workers--is more than twice as high as that calculated in 2004 in Italy in regular non-EU workers (approximately 65 accidents per 1000). The difference can be explained by the fact that irregular workers find employment mainly in agriculture, building and the metallurgic industry, which have a high frequency of accidents, and are more willing to accept risky work and longer work shifts. On the assumption that the rate of occupational accidents in the 500,000 irregular workers living in Italy in 2004 was 147.2 per 1000 (as in the catchment area of the San Bonifacio Hospital), the number of accidents would be 73,600, against the 116,000 that occurred

Patient-specific radiation dose and cancer risk estimation in pediatric chest CT: a study in 30 patients

NASA Astrophysics Data System (ADS)

Li, Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P.

2010-04-01

Radiation-dose awareness and optimization in CT can greatly benefit from a dosereporting system that provides radiation dose and cancer risk estimates specific to each patient and each CT examination. Recently, we reported a method for estimating patientspecific dose from pediatric chest CT. The purpose of this study is to extend that effort to patient-specific risk estimation and to a population of pediatric CT patients. Our study included thirty pediatric CT patients (16 males and 14 females; 0-16 years old), for whom full-body computer models were recently created based on the patients' clinical CT data. Using a validated Monte Carlo program, organ dose received by the thirty patients from a chest scan protocol (LightSpeed VCT, 120 kVp, 1.375 pitch, 40-mm collimation, pediatric body scan field-of-view) was simulated and used to estimate patient-specific effective dose. Risks of cancer incidence were calculated for radiosensitive organs using gender-, age-, and tissue-specific risk coefficients and were used to derive patientspecific effective risk. The thirty patients had normalized effective dose of 3.7-10.4 mSv/100 mAs and normalized effective risk of 0.5-5.8 cases/1000 exposed persons/100 mAs. Normalized lung dose and risk of lung cancer correlated strongly with average chest diameter (correlation coefficient: r = -0.98 to -0.99). Normalized effective risk also correlated strongly with average chest diameter (r = -0.97 to -0.98). These strong correlations can be used to estimate patient-specific dose and risk prior to or after an imaging study to potentially guide healthcare providers in justifying CT examinations and to guide individualized protocol design and optimization.

Measurement of soil contamination by radionuclides due to the Fukushima Dai-ichi Nuclear Power Plant accident and associated estimated cumulative external dose estimation.

PubMed

Endo, S; Kimura, S; Takatsuji, T; Nanasawa, K; Imanaka, T; Shizuma, K

2012-09-01

Soil sampling was carried out at an early stage of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Samples were taken from areas around FDNPP, at four locations northwest of FDNPP, at four schools and in four cities, including Fukushima City. Radioactive contaminants in soil samples were identified and measured by using a Ge detector and included (129 m)Te, (129)Te, (131)I, (132)Te, (132)I, (134)Cs, (136)Cs, (137)Cs, (140)Ba and (140)La. The highest soil depositions were measured to the northwest of FDNPP. From this soil deposition data, variations in dose rates over time and the cumulative external doses at the locations for 3 months and 1y after deposition were estimated. At locations northwest of FDNPP, the external dose rate at 3 months after deposition was 4.8-98 μSv/h and the cumulative dose for 1 y was 51 to 1.0 × 10(3)mSv; the highest values were at Futaba Yamada. At the four schools, which were used as evacuation shelters, and in the four urban cities, the external dose rate at 3 months after deposition ranged from 0.03 to 3.8μSv/h and the cumulative doses for 1 y ranged from 3 to 40 mSv. The cumulative dose at Fukushima Niihama Park was estimated as the highest in the four cities. The estimated external dose rates and cumulative doses show that careful countermeasures and remediation will be needed as a result of the accident, and detailed measurements of radionuclide deposition densities in soil will be important input data to conduct these activities. Copyright © 2011 Elsevier Ltd. All rights reserved.

Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Xiang; Samei, Ehsan; Segars, W. Paul

2011-01-15

Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GEmore » Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller