Cytogenetic damages in peripheral blood of monkey lymphocytes under simulation of cosmonauts irradiation.

NASA Astrophysics Data System (ADS)

Petrov, Vladislav; Ivanov, Alexandr; Barteneva, Svetlana; Snigiryeva, Galina; Shafirkin, Alexandr

Earth modeling of crewmember exposure should be performed for correct estimating radiation hazard during the flight. Such modeling was planned in a monkey experiment for investigating consequences of exposure to a man during an interplanetary flight. It should reflect a chronic impact of galactic cosmic rays and acute and fractional irradiation specified for solar cosmic rays and radiation belts respectively. Due to the difficulty of modeling a chronic impact with the help of a charged particles accelerator it can be used the gamma source. While irradiating big animal groups during a long-term period of time it is preferably to replace chronic irradiation by an equal fractional one. In this case the chosen characteristics of fractional irradiation should ensure the appearances of radiobiological consequences equal to the ones caused by the modeled chronic exposure. So for developing an exposure scheme in the monkey experiment (with Macaca -Rhesus) the model of the acting residual dose, that takes into account repair and recovery processes in the exposed body was used. The total dose value was in the limits from 2.32 Gy up to 3.5 Gy depending on the exposure character. The acting residual dose in all versions of exposure was 2.0 Gy for every monkey. While performing the experiment all the requirements of bioethics for the work with animals were observed. The objects of interest were genomic damages in lymphocytes of monkey's peripheral blood. The data about the CAF during the exposure and at various time moments after exposure particularly directly after the completion of chronicle and fractional irradiation were analyzed. CAF -dose of acute single gamma-irradiation in the range 0 -1.5Gy relationship (calibration curve) was defined in vitro. In addition the rate of the aberrant cells elimination within three months after the irradiation completion was estimated. On the basis of the obtained CAF data we performed verification of applicability of cytogenetic analysis for estimating the monkey gamma -dose exposure in the experiment It was obtained that this method permits to estimate the acting residual dose with accuracy of 30

Assessing human health response in life cycle assessment using ED10s and DALYs: part 2--Noncancer effects.

PubMed

Pennington, David; Crettaz, Pierre; Tauxe, Annick; Rhomberg, Lorenz; Brand, Kevin; Jolliet, Olivier

2002-10-01

In Part 1 of this article we developed an approach for the calculation of cancer effect measures for life cycle assessment (LCA). In this article, we propose and evaluate the method for the screening of noncancer toxicological health effects. This approach draws on the noncancer health risk assessment concept of benchmark dose, while noting important differences with regulatory applications in the objectives of an LCA study. We adopt the centraltendency estimate of the toxicological effect dose inducing a 10% response over background, ED10, to provide a consistent point of departure for default linear low-dose response estimates (betaED10). This explicit estimation of low-dose risks, while necessary in LCA, is in marked contrast to many traditional procedures for noncancer assessments. For pragmatic reasons, mechanistic thresholds and nonlinear low-dose response curves were not implemented in the presented framework. In essence, for the comparative needs of LCA, we propose that one initially screens alternative activities or products on the degree to which the associated chemical emissions erode their margins of exposure, which may or may not be manifested as increases in disease incidence. We illustrate the method here by deriving the betaED10 slope factors from bioassay data for 12 chemicals and outline some of the possibilities for extrapolation from other more readily available measures, such as the no observable adverse effect levels (NOAEL), avoiding uncertainty factors that lead to inconsistent degrees of conservatism from chemical to chemical. These extrapolations facilitated the initial calculation of slope factors for an additional 403 compounds; ranging from 10(-6) to 10(3) (risk per mg/kg-day dose). The potential consequences of the effects are taken into account in a preliminary approach by combining the betaED10 with the severity measure disability adjusted life years (DALY), providing a screening-level estimate of the potential consequences associated with exposures, integrated over time and space, to a given mass of chemical released into the environment for use in LCA.

Assessing human health response in life cycle assessment using ED10s and DALYs: part 1--Cancer effects.

PubMed

Crettaz, Pierre; Pennington, David; Rhomberg, Lorenz; Brand, Kevin; Jolliet, Olivier

2002-10-01

Life cycle assessment (LCA) is a framework for comparing products according to their total estimated environmental impact, summed over all chemical emissions and activities associated with a product at all stages in its life cycle (from raw material acquisition, manufacturing, use, to final disposal). For each chemical involved, the exposure associated with the mass released into the environment, integrated over time and space, is multiplied by a toxicological measure to estimate the likelihood of effects and their potential consequences. In this article, we explore the use of quantitative methods drawn from conventional single-chemical regulatory risk assessments to create a procedure for the estimation of the cancer effect measure in the impact phase of LCA. The approach is based on the maximum likelihood estimate of the effect dose inducing a 10% response over background, ED10, and default linear low-dose extrapolation using the slope betaED10 (0.1/ED10). The calculated effects may correspond to residual risks below current regulatory compliance requirements that occur over multiple generations and at multiple locations; but at the very least they represent a "using up" of some portion of the human population's ability to accommodate emissions. Preliminary comparisons are performed with existing measures, such as the U.S. Environmental Protection Agency's (U.S. EPA's) slope factor measure q1*. By analyzing bioassay data for 44 chemicals drawn from the EPA's Integrated Risk Information System (IRIS) database, we explore estimating ED10 from more readily available information such as the median tumor dose rate TD50 and the median single lethal dose LD50. Based on the TD50, we then estimate the ED10 for more than 600 chemicals. Differences in potential consequences, or severity, are addressed by combining betaED10 with the measure disability adjusted life years per affected person, DALYp. Most of the variation among chemicals for cancer effects is found to be due to differences in the slope factors (betaED10) ranging from 10(-4) up to 10(4) (risk of cancer/mg/kg-day).

Influence of measurement frequency on the evaluation of short-term dose of sub-micrometric particles during indoor and outdoor generation events

NASA Astrophysics Data System (ADS)

Manigrasso, M.; Stabile, L.; Avino, P.; Buonanno, G.

2013-03-01

Aerosol generation events due to combustion processes are characterized by high particle emissions in the nucleation mode range. Such particles are characterized by very short atmospheric lifetimes, leading to rapid decay in time and space from the emission point. Therefore, the deposited fraction of inhaled particles (dose) also changes. In fact, close to the emission source, high short-term peak exposures occur. The related exposure estimates should therefore rely on measurements of aerosol number-size distributions able to track rapid aerosol dynamics. In order to study the influence of the time resolution on such estimates, simultaneous measurements were carried out via Scanning Mobility Particle Sizer (SMPS) and Fast Mobility Particle Sizer (FMPS) spectrometers during particle generation events in both indoor (cooking activities) and outdoor (airstrip and urban street canyons) microenvironments. Aerosol size distributions in the range 16-520 nm were measured by SMPS and FMPS at frequencies of 0.007 s-1 and 1 s-1, respectively. Based on the two datasets, respiratory dosimetry estimates were made on the basis of the deposition model of the International Commission on Radiological Protection. During cooking activities, SMPS measurements give an approximate representation of aerosol temporal evolution. Consequently, the related instant doses can be approximated to a fair degree. In the two outdoor microenvironments considered, aerosol size distributions change rapidly: the FMPS is able to follow such evolution, whereas the SMPS is not. The high short-term peak concentrations, and the consequent respiratory doses, evidenced by FMPS data are hardly described by SMPS, which is unable to track the fast aerosol changes. The health relevance of such short peak exposures has not been thoroughly investigated in scientific literature, therefore, in the present paper highly time-resolved and size-resolved dosimetry estimates were provided in order to deepen this aspect.

²¹⁰Po in the diet at Seville (Spain) and its contribution to the dose by ingestion.

PubMed

Díaz-Francés, I; Mantero, J; Díaz-Ruiz, J; Manjón, G; García-Tenorio, R

2016-02-01

The activity concentrations of (210)Po have been determined in a total of 24 representative diet samples from Seville (south of Spain), inferring from the obtained values the annual intakes of (210)Po by ingestion of the affected population and the corresponding committed effective doses. The annual intakes of (210)Po and, consequently, the corresponding doses of this radionuclide show a high variability in correspondence with the variability in the composition of the analysed samples over time, and their magnitude is comparable with the estimated ones in other regions/countries of the world with similar diet habits (countries where the marine products have a considerable weight in the diets). Committed effective doses by ingestion higher than 0.1 mSv y(-1) have been estimated exclusively for (210)Po, reflecting the importance of this radionuclide and this route of incorporation in the magnitude of the total doses received by the affected population from natural sources. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

PubMed

Drozdovitch, Vladimir; Chumak, Vadim; Kesminiene, Ausrele; Ostroumova, Evgenia; Bouville, André

2016-09-01

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

Radiation exposure related to the shipment of fertilisers to and from commercial ports: the case study of the seaport of Ravenna (Italy).

PubMed

Righi, Serena; Lucialli, Patrizia; Pollini, Elisa

2014-03-01

This paper presents the results of a study of radiological impacts related to the shipment of fertilisers to and from the commercial port of Ravenna (NE Italy). In particular, the effective doses to the port workers and members of the population surrounding the port area have been estimated. The study has included different types of measurement and assessment. First, the natural radioactivity of different fertilisers moving through the port has been determined: (40)K, (226)Ra, (210)Pb, (228)Ra and (228)Th concentrations have been analysed using γ-ray spectrometry, while (238)U and (232)Th concentrations have been determined by ICP-MS. At the same time, a dose rate meter and electret ion chambers were used to measure the external irradiation and the radon concentrations, respectively. Then, air pollutant dispersion models have been applied in order to assess particulate matter concentration in the port site and the surrounding residential areas, and consequently the inhalation doses. Finally, the annual effective doses to workers and local residents have been estimated. The effective doses to workers and the population have been estimated to be 0.9 mSv yr(-1) and 0.07 μSv yr(-1), respectively.

Environmental consequences of postulated plutonium releases from Westinghouse PFDL, Cheswick, Pennsylvania, as a result of severe natural phenomena

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

McPherson, R.B.; Watson, E.C.

1979-06-01

Potential environmental consequences in terms of radiation dose to people are presented for postulated accidents due to earthquakes, tornadoes, high straight-line winds, and floods. Maximum plutonium deposition values are given for significant locations around the site. All important potential exposure pathways are examined. The most likely calculated 50-year collective committed dose equivalents are all much lower than the collective dose equivalent expected from 50 years of exposure to natural background radiation and medical x-rays except Earthquake No. 4 and the 260-mph tornado. The most likely maximum residual plutonium contamination estimated to be deposited offsite following Earthquake No. 4, and themore » 200-mph and 260-mph tornadoes are above the Environmental Protection Agency's (EPA) proposed guideline for plutonium in the general environment of 0.2 ..mu..Ci/m/sup 2/. The deposition values following the other severe natural phenomena are below the EPA proposed guideline.« less

Risk of Lung Cancer Mortality in Nuclear Workers from Internal Exposure to Alpha Particle-emitting Radionuclides

PubMed Central

Atkinson, Will; Bérard, Philippe; Bingham, Derek; Birchall, Alan; Blanchardon, Eric; Bull, Richard; Guseva Canu, Irina; Challeton-de Vathaire, Cécile; Cockerill, Rupert; Do, Minh T.; Engels, Hilde; Figuerola, Jordi; Foster, Adrian; Holmstock, Luc; Hurtgen, Christian; Laurier, Dominique; Puncher, Matthew; Riddell, Anthony E.; Samson, Eric; Thierry-Chef, Isabelle; Tirmarche, Margot; Vrijheid, Martine; Cardis, Elisabeth

2017-01-01

Background: Carcinogenic risks of internal exposures to alpha-emitters (except radon) are poorly understood. Since exposure to alpha particles—particularly through inhalation—occurs in a range of settings, understanding consequent risks is a public health priority. We aimed to quantify dose–response relationships between lung dose from alpha-emitters and lung cancer in nuclear workers. Methods: We conducted a case–control study, nested within Belgian, French, and UK cohorts of uranium and plutonium workers. Cases were workers who died from lung cancer; one to three controls were matched to each. Lung doses from alpha-emitters were assessed using bioassay data. We estimated excess odds ratio (OR) of lung cancer per gray (Gy) of lung dose. Results: The study comprised 553 cases and 1,333 controls. Median positive total alpha lung dose was 2.42 mGy (mean: 8.13 mGy; maximum: 316 mGy); for plutonium the median was 1.27 mGy and for uranium 2.17 mGy. Excess OR/Gy (90% confidence interval)—adjusted for external radiation, socioeconomic status, and smoking—was 11 (2.6, 24) for total alpha dose, 50 (17, 106) for plutonium, and 5.3 (−1.9, 18) for uranium. Conclusions: We found strong evidence for associations between low doses from alpha-emitters and lung cancer risk. The excess OR/Gy was greater for plutonium than uranium, though confidence intervals overlap. Risk estimates were similar to those estimated previously in plutonium workers, and in uranium miners exposed to radon and its progeny. Expressed as risk/equivalent dose in sieverts (Sv), our estimates are somewhat larger than but consistent with those for atomic bomb survivors. See video abstract at, http://links.lww.com/EDE/B232. PMID:28520643

Holick's rule and vitamin D from sunlight.

PubMed

Dowdy, John C; Sayre, Robert M; Holick, Michael F

2010-07-01

Holick's rule says that sun exposure 1/4 of a minimal erythemal dose (MED) over 1/4 of a body is equivalent to 1000 International Units (IU) oral vitamin D3. Webb and Engelsen recently commented that the ultraviolet (UV) spectrum used to establish Holick's rule is unknown. They consequently used a spring midday Boston solar spectrum to estimate ample sunlight exposures for previtamin D3 (preD3) at various locations. Literature review found the source upon which this rule is based was a fluorescent sunlamp (FS lamp). The FS spectrum is known and its relative weighting against the action spectra for erythema and the preD3 is significantly different from the solar spectrum used to derive the standard vitamin D effective dose (SDD). The preD3 effectiveness of the solar spectrum per unit erythemal hazard is greater than the FS lamp by a factor of 1.32. Consequently, UV exposure estimates based on Boston reference sunlight, instead of the UV lamp employed in the originating experiments, over estimate UV exposure equivalent to approximately 1000 IU orally by approximately 1/3. This redefinition of SDD impacts risk/benefit assessments of optimal/feasible sun exposure for vitamin D maintenance and the application of Holick's rule to rational public health messages. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

An updated dose assessment for resettlement options at Bikini Atoll--a U.S. nuclear test site.

PubMed

Robison, W L; Bogen, K T; Conrado, C L

1997-07-01

On 1 March 1954, a nuclear weapon test, code-named BRAVO, conducted at Bikini Atoll in the northern Marshall Islands contaminated the major residence island. There has been a continuing effort since 1977 to refine dose assessments for resettlement options at Bikini Atoll. Here we provide a radiological dose assessment for the main residence island, Bikini, using extensive radionuclide concentration data derived from analysis of food crops, ground water, cistern water, fish and other marine species, animals, air, and soil collected at Bikini Island as part of our continuing research and monitoring program that began in 1978. The unique composition of coral soil greatly alters the relative contribution of 137Cs and 90Sr to the total estimated dose relative to expectations based on North American and European soils. Without counter measures, 137Cs produces 96% of the estimated dose for returning residents, mostly through uptake from the soil to terrestrial food crops but also from external gamma exposure. The doses are calculated assuming a resettlement date of 1999. The estimated maximum annual effective dose for current island conditions is 4.0 mSv when imported foods, which are now an established part of the diet, are available. The 30-, 50-, and 70-y integral effective doses are 91 mSv, 130 mSv, and 150 mSv, respectively. A detailed uncertainty analysis for these dose estimates is presented in a companion paper in this issue. We have evaluated various countermeasures to reduce 137Cs in food crops. Treatment with potassium reduces the uptake of 137Cs into food crops, and therefore the ingestion dose, to about 5% of pretreatment levels and has essentially no negative environmental consequences. We have calculated the dose for the rehabilitation scenario where the top 40 cm of soil is removed in the housing and village area, and the rest of the island is treated with potassium fertilizer; the maximum annual effective dose is 0.41 mSv and the 30-, 50-, and 70-y integral effective doses are 9.8 mSv, 14 mSv, and 16 mSv, respectively.

Remanent dose rates around the collimators of the LHC beam cleaning insertions.

PubMed

Brugger, M; Roesler, S

2005-01-01

The LHC will require an extremely powerful and unprecedented collimation system. As approximately 30% of the LHC beam is lost in the cleaning insertions, these will become some of the most radioactive locations around the entire LHC ring. Thus, remanent dose rates to be expected during later repair or maintenance interventions must be considered in the design phase itself. As a consequence, the beam cleaning insertions form a unique test bed for a recently developed approach to calculate remanent dose rates. A set of simulations, different in complexity, is used in order to evaluate methods for the estimation of remanent dose rates. The scope, as well as the restrictions, of the omega-factor method are shown and compared with the explicit simulation approach. The latter is then used to calculate remanent dose rates in the beam cleaning insertions. Furthermore, a detailed example for maintenance dose planning is given.

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

PIEPHO, M.G.

Four bounding accidents postulated for the K West Basin integrated water treatment system are evaluated against applicable risk evaluation guidelines. The accidents are a spray leak during fuel retrieval, spray leak during backflushing a hydrogen explosion, and a fire breaching filter vessel and enclosure. Event trees and accident probabilities are estimated. In all cases, the unmitigated dose consequences are below the risk evaluation guidelines.

Vaccine-associated paralytic poliomyelitis in India during 1999: decreased risk despite massive use of oral polio vaccine.

PubMed Central

Kohler, Kathryn A.; Banerjee, Kaushik; Gary Hlady, W.; Andrus, Jon K.; Sutter, Roland W.

2002-01-01

OBJECTIVE: Vaccine-associated paralytic poliomyelitis (VAPP) is a rare but serious consequence of the administration of oral polio vaccine (OPV). Intensified OPV administration has reduced wild poliovirus transmission in India but VAPP is becoming a matter of concern. METHODS: We analysed acute flaccid paralysis (AFP) surveillance data in order to estimate the VAPP risk in this country. VAPP was defined as occurring in AFP cases with onset of paralysis in 1999, residual weakness 60 days after onset, and isolation of vaccine-related poliovirus. Recipient VAPP cases were a subset with onset of paralysis between 4 and 40 days after receipt of OPV. FINDINGS: A total of 181 AFP cases met the case definition. The following estimates of VAPP risk were made: overall risk, 1 case per 4.1 to 4.6 million OPV doses administered; recipient risk,1 case per 12.2 million; first-dose recipient risk, 1 case per 2.8 million; and subsequent-dose recipient risk, 1 case per 13.9 million. CONCLUSION: On the basis of data from a highly sensitive surveillance system the estimated VAPP risk in India is evidently lower than that in other countries, notwithstanding the administration of multiple OPV doses to children in mass immunization campaigns. PMID:11984607

SU-F-J-14: Kilovoltage Cone-Beam CT Dose Estimation of Varian On-Board Imager Using GMctdospp Monte Carlo Framework

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

Kim, S; Rangaraj, D

2016-06-15

Purpose: Although cone-beam CT (CBCT) imaging became popular in radiation oncology, its imaging dose estimation is still challenging. The goal of this study is to assess the kilovoltage CBCT doses using GMctdospp - an EGSnrc based Monte Carlo (MC) framework. Methods: Two Varian OBI x-ray tube models were implemented in the GMctpdospp framework of EGSnrc MC System. The x-ray spectrum of 125 kVp CBCT beam was acquired from an EGSnrc/BEAMnrc simulation and validated with IPEM report 78. Then, the spectrum was utilized as an input spectrum in GMctdospp dose calculations. Both full and half bowtie pre-filters of the OBI systemmore » were created by using egs-prism module. The x-ray tube MC models were verified by comparing calculated dosimetric profiles (lateral and depth) to ion chamber measurements for a static x-ray beam irradiation to a cuboid water phantom. An abdominal CBCT imaging doses was simulated in GMctdospp framework using a 5-year-old anthropomorphic phantom. The organ doses and effective dose (ED) from the framework were assessed and compared to the MOSFET measurements and convolution/superposition dose calculations. Results: The lateral and depth dose profiles in the water cuboid phantom were well matched within 6% except a few areas - left shoulder of the half bowtie lateral profile and surface of water phantom. The organ doses and ED from the MC framework were found to be closer to MOSFET measurements and CS calculations within 2 cGy and 5 mSv respectively. Conclusion: This study implemented and validated the Varian OBI x-ray tube models in the GMctdospp MC framework using a cuboid water phantom and CBCT imaging doses were also evaluated in a 5-year-old anthropomorphic phantom. In future study, various CBCT imaging protocols will be implemented and validated and consequently patient CT images will be used to estimate the CBCT imaging doses in patients.« less

Quantities for assessing high photon doses to the body: a calculational approach.

PubMed

Eakins, Jonathan S; Ainsbury, Elizabeth A

2018-06-01

Tissue reactions are the most clinically significant consequences of high-dose exposures to ionising radiation. However, currently there is no universally recognized dose quantity that can be used to assess and report generalised risks to individuals following whole body exposures in the high-dose range. In this work, a number of potential dose quantities are presented and discussed, with mathematical modelling techniques employed to compare them and explore when their differences are most or least manifest. The results are interpreted to propose the average (D GRB ) of the absorbed doses to the stomach, small intestine, red bone marrow, and brain as the optimum quantity for informing assessments of risk. A second, maximally conservative dose quantity (D Max ) is also suggested, which places limits on any under-estimates resulting from the adoption of D GRB . The primary aim of this work is to spark debate, with further work required to refine the final choice of quantity or quantities most appropriate for the full range of different potential exposure scenarios.

Assessment of environmental consequences of the normal operations of the ESS facility

NASA Astrophysics Data System (ADS)

Ene, D.; Avila, R.; Hjerpe, T.; Bugay, D.; Stenberg, K.

2018-06-01

As other accelerator based facilities, the European Spallation Source ESS facility will interact with the environment. The Swedish legislation requires a demonstration that the sum of the doses resulting from the exposure of any member of the public to ionizing radiation dose does not exceed the specified limit of 50 μSv/year. A radiological assessment has been produced to provide that demonstration. This evaluation was based upon the actual status of the ESS design. A graded approach was adopted through over the assessment allowing estimating dose for all radionuclides and exposure pathways, but the degree of detail in the assessment depend upon their relative radiological importance. The total dose was obtained making the sum of the contribution of all-important radionuclides treated realistically with that of all screened out radionuclides, derived by means a conservative method.

Toward endobronchial Ir-192 high-dose-rate brachytherapy therapeutic optimization

NASA Astrophysics Data System (ADS)

Gay, H. A.; Allison, R. R.; Downie, G. H.; Mota, H. C.; Austerlitz, C.; Jenkins, T.; Sibata, C. H.

2007-06-01

A number of patients with lung cancer receive either palliative or curative high-dose-rate (HDR) endobronchial brachytherapy. Up to a third of patients treated with endobronchial HDR die from hemoptysis. Rather than accept hemoptysis as an expected potential consequence of HDR, we have calculated the radial dose distribution for an Ir-192 HDR source, rigorously examined the dose and prescription points recommended by the American Brachytherapy Society (ABS), and performed a radiobiological-based analysis. The radial dose rate of a commercially available Ir-192 source was calculated with a Monte Carlo simulation. Based on the linear quadratic model, the estimated palliative, curative and blood vessel rupture radii from the center of an Ir-192 source were obtained for the ABS recommendations and a series of customized HDR prescriptions. The estimated radius at risk for blood vessel perforation for the ABS recommendations ranges from 7 to 9 mm. An optimized prescription may in some situations reduce this radius to 4 mm. The estimated blood perforation radius is generally smaller than the palliative radius. Optimized and individualized endobronchial HDR prescriptions are currently feasible based on our current understanding of tumor and normal tissue radiobiology. Individualized prescriptions could minimize complications such as fatal hemoptysis without sacrificing efficacy. Fiducial stents, HDR catheter centering or spacers and the use of CT imaging to better assess the relationship between the catheter and blood vessels promise to be useful strategies for increasing the therapeutic index of this treatment modality. Prospective trials employing treatment optimization algorithms are needed.

Genetic effects of radiotherapy for childhood cancer: gonadal dose reconstruction.

PubMed

Stovall, Marilyn; Donaldson, Sarah S; Weathers, Rita E; Robison, Leslie L; Mertens, Ann C; Winther, Jeanette Falck; Olsen, Jorgen H; Boice, John D

2004-10-01

To estimate the doses of radiation to organs of interest during treatment of childhood cancer for use in an epidemiologic study of possible heritable diseases, including birth defects, chromosomal abnormalities, cancer, stillbirth, and neonatal and premature death. The study population was composed of more than 25,000 patients with cancer in Denmark and the United States who were survivors of childhood cancer and subsequently had nearly 6,500 children of their own. Radiation therapy records were sought for the survivors who parented offspring who had adverse pregnancy outcomes (>300 offspring), and for a sample of all survivors in a case-cohort design. The records were imaged and centrally abstracted. Water phantom measurements were made to estimate doses for a wide range of treatments. Mathematical phantoms were used to apply measured results to estimate doses to ovaries, uterus, testes, and pituitary for patients ranging in age from newborn to 25 years. Gonadal shielding, ovarian pinning (oophoropexy), and field blocking were taken into account. Testicular radiation doses ranged from <1 to 700 cGy (median, 7 cGy) and ovarian doses from <1 to >2,500 cGy (median, 13 cGy). Ten percent of the records were incomplete, but sufficient data were available for broad characterizations of gonadal dose. More than 49% of the gonadal doses were >10 cGy and 16% were >100 cGy. Sufficient radiation therapy data exist as far back as 1943 to enable computation of gonadal doses administered for curative therapy for childhood cancer. The range of gonadal doses is broad, and for many cancer survivors, is high and just below the threshold for infertility. Accordingly, the epidemiologic study has >90% power to detect a 1.3-fold risk of an adverse pregnancy outcome associated with radiation exposure to the gonads. This study should provide important information on the genetic consequences of radiation exposure to humans.

A geometric model for evaluating the effects of inter-fraction rectal motion during prostate radiotherapy

NASA Astrophysics Data System (ADS)

Pavel-Mititean, Luciana M.; Rowbottom, Carl G.; Hector, Charlotte L.; Partridge, Mike; Bortfeld, Thomas; Schlegel, Wolfgang

2004-06-01

A geometric model is presented which allows calculation of the dosimetric consequences of rectal motion in prostate radiotherapy. Variations in the position of the rectum are measured by repeat CT scanning during the courses of treatment of five patients. Dose distributions are calculated by applying the same conformal treatment plan to each imaged fraction and rectal dose-surface histograms produced. The 2D model allows isotropic expansion and contraction in the plane of each CT slice. By summing the dose to specific volume elements tracked by the model, composite dose distributions are produced that explicitly include measured inter-fraction motion for each patient. These are then used to estimate effective dose-surface histograms (DSHs) for the entire treatment. Results are presented showing the magnitudes of the measured target and rectal motion and showing the effects of this motion on the integral dose to the rectum. The possibility of using such information to calculate normal tissue complication probabilities (NTCP) is demonstrated and discussed.

Environmental consequences of postulate plutonium releases from Atomics International's Nuclear Materials Development Facility (NMDF), Santa Susana, California, as a result of severe natural phenomena

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

Jamison, J.D.; Watson, E.C.

1982-02-01

Potential environmental consequences in terms of radiation dose to people are presented for postulated plutonium releases caused by severe natural phenomena at the Atomics International's Nuclear Materials Development Facility (NMDF), in the Santa Susana site, California. The severe natural phenomena considered are earthquakes, tornadoes, and high straight-line winds. Plutonium deposition values are given for significant locations around the site. All important potential exposure pathways are examined. The most likely 50-year committed dose equivalents are given for the maximum-exposed individual and the population within a 50-mile radius of the plant. The maximum plutonium deposition values likely to occur offsite are alsomore » given. The most likely calculated 50-year collective committed dose equivalents are all much lower than the collective dose equivalent expected from 50 years of exposure to natural background radiation and medical x-rays. The most likely maximum residual plutonium contamination estimated to be deposited offsite following the earthquake, and the 150-mph and 170-mph tornadoes are above the Environmental Protection Agency's (EPA) proposed guideline for plutonium in the general environment of 0.2 ..mu..Ci/m/sup 2/. The deposition values following the 110-mph and the 130-mph tornadoes are below the EPA proposed guideline.« less

Environmental consequences of postulated plutonium releases from General Electric Company Vallecitos Nuclear Center, Vallecitos, California, as a result of severe natural phenomena

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

Jamison, J.D.; Watson, E.C.

1980-11-01

Potential environmental consequences in terms of radiation dose to people are presented for postulated plutonium releases caused by severe natural phenomena at the General Electric Company Vallecitos Nuclear Center, Vallecitos, California. The severe natural phenomena considered are earthquakes, tornadoes, and high straight-line winds. Maximum plutonium deposition values are given for significant locations around the site. All important potential exposure pathways are examined. The most likely 50-year committed dose equivalents are given for the maximum-exposed individual and the population within a 50-mile radius of the plant. The maximum plutonium deposition values likely to occur offsite are also given. The most likelymore » calculated 50-year collective committed dose equivalents are all much lower than the collective dose equivalent expected from 50 years of exposure to natural background radiation and medical x-rays. The most likely maximum residual plutonium contamination estimated to be deposited offsite following the earthquakes, and the 180-mph and 230-mph tornadoes are above the Environmental Protection Agency's (EPA) proposed guideline for plutonium in the general environment of 0.2 ..mu..Ci/m/sup 2/. The deposition values following the 135-mph tornado are below the EPA proposed guidelines.« less

SU-E-T-248: An Extended Generalized Equivalent Uniform Dose Accounting for Dose-Range Dependency of Radio-Biological Parameters.

PubMed

Troeller, A; Soehn, M; Yan, D

2012-06-01

Introducing an extended, phenomenological, generalized equivalent uniform dose (eEUD) that incorporates multiple volume-effect parameters for different dose-ranges. The generalized EUD (gEUD) was introduced as an estimate of the EUD that incorporates a single, tissue-specific parameter - the volume-effect-parameter (VEP) 'a'. As a purely phenomenological concept, its radio-biological equivalency to a given inhomogeneous dose distribution is not a priori clear and mechanistic models based on radio-biological parameters are assumed to better resemble the underlying biology. However, for normal organs mechanistic models are hard to derive, since the structural organization of the tissue plays a significant role. Consequently, phenomenological approaches might be especially useful in order to describe dose-response for normal tissues. However, the single parameter used to estimate the gEUD may not suffice in accurately representing more complex biological effects that have been discussed in the literature. For instance, radio-biological parameters and hence the effects of fractionation are known to be dose-range dependent. Therefore, we propose an extended phenomenological eEUD formula that incorporates multiple VEPs accounting for dose-range dependency. The eEUD introduced is a piecewise polynomial expansion of the gEUD formula. In general, it allows for an arbitrary number of VEPs, each valid for a certain dose-range. We proved that the formula fulfills required mathematical and physical criteria such as invertibility of the underlying dose-effect and continuity in dose. Furthermore, it contains the gEUD as a special case, if all VEPs are equal to 'a' from the gEUD model. The eEUD is a concept that expands the gEUD such that it can theoretically represent dose-range dependent effects. Its practicality, however, remains to be shown. As a next step, this will be done by estimating the eEUD from patient data using maximum-likelihood based NTCP modelling in the same way it is commonly done for the gEUD. © 2012 American Association of Physicists in Medicine.

Development of Northeast Asia Nuclear Power Plant Accident Simulator.

PubMed

Kim, Juyub; Kim, Juyoul; Po, Li-Chi Cliff

2017-06-15

A conclusion from the lessons learned after the March 2011 Fukushima Daiichi accident was that Korea needs a tool to estimate consequences from a major accident that could occur at a nuclear power plant located in a neighboring country. This paper describes a suite of computer-based codes to be used by Korea's nuclear emergency response staff for training and potentially operational support in Korea's national emergency preparedness and response program. The systems of codes, Northeast Asia Nuclear Accident Simulator (NANAS), consist of three modules: source-term estimation, atmospheric dispersion prediction and dose assessment. To quickly assess potential doses to the public in Korea, NANAS includes specific reactor data from the nuclear power plants in China, Japan and Taiwan. The completed simulator is demonstrated using data for a hypothetical release. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Pharmacokinetics of paracetamol (acetaminophen) after intravenous and oral administration.

PubMed

Rawlins, M D; Henderson, D B; Hijab, A R

1977-04-20

Plasma paracetamol concentrations were measured in 6 volunteers after single intravenous (1000 mg) and oral (500 mg, 1000 mg and 2000 mg) doses of the drug. Paracetamol levels declined multiphasically with a mean clearance after intravenous administration of 352 +/- 40 ml/min. A two-compartment open model appeared to describe the decline adequately. Comparison of the areas under the plasma concentration-time curves (AUC) indicated that oral bioavailability increased from 0.63 +/- 0.02 after 500 mg, to 0.89 +/- 0.04 and 0.87 +/- 0.08 after 1000 mg and 2000 mg, respectively. As a consequence of the incomplete bioavailability of paracetamol, as well as its multicompartmental distribution, accurate estimates of its distribution volume and clearance cannot be obtained if the drug is given orally. However, an estimate of its total plasma clearance may be derived from the AUC after a 500 mg oral dose.

Cancer risk above 1 Gy and the impact for space radiation protection

NASA Astrophysics Data System (ADS)

Schneider, Uwe; Walsh, Linda

2009-07-01

Analyses of the epidemiological data on the Japanese A-bomb survivors, who were exposed to γ-rays and neutrons, provide most current information on the dose-response of radiation-induced cancer. Since the dose span of main interest is usually between 0 and 1 Gy, for radiation protection purposes, the analysis of the A-bomb survivors is often focused on this range. However, estimates of cancer risk for doses larger than 1 Gy are becoming more important for long-term manned space missions. Therefore in this work, emphasis is placed on doses larger than 1 Gy with respect to radiation-induced solid cancer and leukemia mortality. The present analysis of the A-bomb survivors data was extended by including two extra high-dose categories and applying organ-averaged dose instead of the colon-weighted dose. In addition, since there are some recent indications for a high neutron dose contribution, the data were fitted separately for three different values for the relative biological effectiveness (RBE) of the neutrons (10, 35 and 100) and a variable RBE as a function of dose. The data were fitted using a linear and a linear-exponential dose-response relationship using a dose and dose-rate effectiveness factor (DDREF) of both one and two. The work presented here implies that the use of organ-averaged dose, a dose-dependent neutron RBE and the bending-over of the dose-response relationship for radiation-induced cancer could result in a reduction of radiation risk by around 50% above 1 Gy. This could impact radiation risk estimates for space crews on long-term mission above 500 days who might be exposed to doses above 1 Gy. The consequence of using a DDREF of one instead of two increases cancer risk by about 40% and would therefore balance the risk decrease described above.

Organ biodistribution of Germanium-68 in rat in the presence and absence of [68Ga]Ga-DOTA-TOC for the extrapolation to the human organ and whole-body radiation dosimetry

PubMed Central

Velikyan, Irina; Antoni, Gunnar; Sörensen, Jens; Estrada, Sergio

2013-01-01

Positron Emission Tomography (PET) and in particular gallium-68 (68Ga) applications are growing exponentially worldwide contributing to the expansion of nuclear medicine and personalized management of patients. The significance of 68Ga utility is reflected in the implementation of European Pharmacopoeia monographs. However, there is one crucial point in the monographs that might limit the use of the generators and consequently expansion of 68Ga applications and that is the limit of 0.001% of Germanium-68 (68Ge(IV)) radioactivity content in a radiopharmaceutical. We have investigated the organ distribution of 68Ge(IV) in rat and estimated human dosimetry parameters in order to provide experimental evidence for the determination and justification of the 68Ge(IV) limit. Male and female rats were injected in the tail vein with formulated [68Ge]GeCl4 in the absence or presence of [68Ga]Ga-DOTA-TOC. The tissue radioactivity distribution data was extrapolated for the estimation of human organ equivalent doses and total effective dose using Organ Level Internal Dose Assessment Code software (OLINDA/EXM). 68Ge(IV) was evenly distributed among the rat organs and fast renal excretion prevailed. Human organ equivalent dose and total effective dose estimates indicated that the kidneys were the dose-limiting organs (185±54 μSv/MBq for female and 171±38 μSv/MBq for male) and the total effective dose was 15.5±0.1 and 10.7±1.2 μSv/MBq, respectively for female and male. The results of this dosimetry study conclude that the 68Ge(IV) limit currently recommended by monographs could be increased considerably (>100 times) without exposing the patient to harm given the small absorbed doses to normal organs and fast excretion. PMID:23526484

Thermoluminescence characteristics of Israeli household salts for retrospective dosimetry in radiological events

NASA Astrophysics Data System (ADS)

Druzhyna, S.; Datz, H.; Horowitz, Y. S.; Oster, L.; Orion, I.

2016-06-01

Following a nuclear accident or terror attack involving the dispersal of radioactive substances, radiation dose assessment to first responders and the members of the public is essential. The need for a retrospective assessment of the radiation dose to those possibly affected is, therefore, obligatory. The present study examines the potential use of Israeli household salt as a retrospective dosimeter (RD). The experiments were carried out on Israeli salt samples (NaCl) following a Nielsen market track survey based on scanning data representing the barcoded market, including organized and independent retail chains and a sample of private minimarkets and supermarkets. The technique used was thermoluminescence (TL) dosimetry. Salt samples were exposed to levels of dose from 0.5 mGy to 300 Gy at the Israeli Secondary Standard Dosimetry Laboratory of the Soreq Nuclear Research Center using a calibrated 137Cs source. Our emphasis has been on a detailed investigation of the basic dosimetric characteristics of the salts including: (i) glow curve analysis (ii) individual glow peak dose response (iii) reproducibility (iv) estimation of minimal measurable dose (v) effect of nitrogen readout, (vi) influence of humidity during pre-irradiation storage and (vii) light induced fading. The results are sufficiently favorable to lead to the conclusion that the Israeli household salts can serve as a pragmatic potential candidate for RD under certain restricted conditions. Occasional pre-calibration of the major salt brands in a dedicated laboratory may be essential depending on the required accuracy in the estimation of dose and consequent clinical evaluation.

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 markedly reduced the external dose to technologists. The doses to technologists varied significantly for different diagnostic applications. Consequently, the estimated annual dose to a technologist performing only a particular scintigraphic procedure is very different from one type of procedure to another. The results of this study should help in determining the rotation time of technologists in different procedures and differences in their individual techniques.

SU-F-J-87: Impact Of The Dosimetric Consequences From Minimal Displacements Throughout The Treatment Time In APBI With SAVI Applicators

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

Chandrasekara, S; Pella, S; Hyvarinen, M

2016-06-15

Purpose: To assess the variation in dose received by the organs at risk (OARs) due to inter-fractional motion by SAVI to determine the importance of providing proper immobilization Methods: An analysis of 15 patients treated with SAVI applicators were considered for this study. Treatment planning teams did not see significant changes in their CT scans through scout images and initial treatment plan was used for the entire treatment. These scans, taken before each treatment were imported in to the treatment planning system and were fused together with respective to the applicator, using landmark registration. Dosimetric evaluations were performed. Dose receivedmore » by skin, ribs and PTV(Planning target volume) respect to the initial treatment plan were measured. Results: Contours of the OARs were not similar with the initial image. Deduction in volumes of PTV and cavity, small deviations in displacements from the applicator to the OARs, difference in doses received by the OARs between treatments were noticed. The maximum, minimum, average doses varied between 10% to 20% 5% to 8% and 15% to 20% in ribs and skin. The 0.1cc doses to OARs showed an average change of 10% of the prescribed dose. PTV was receiving a different dose than the estimated dose Conclusion: The variation in volumes and isodoses related to the OARs, PTV receiving a lesser dose than the prescribed dose indicate that the estimated doses are different from the received dose. This study reveals the urgent need of improving the immobilization methods. Taking a CT scan before each treatment and replanning is helpful to minimize the risk of delivering undesired high doses to the OARs. Patient positioning, motion, respiration, observer differences and time lap between the planning and treating can arise more complications. VacLock, Positioning cushions, Image guided brachytherapy and adjustable registration should be used for further improvements.« less

Assessment of dose rate to terrestrial biota in the area around coal fired power plant applying ERICA tool and RESRAD BIOTA code.

PubMed

Ćujić, Mirjana; Dragović, Snežana

2018-08-01

This paper presents the environmental radiation risk assessment based on two software program approaches ERICA Tool (version 1.2) and RESRAD BIOTA (version 1.5) to estimate dose rates to terrestrial biota in the area around the largest coal fired power plant in Serbia. For dose rate assessment software's default reference animals and plants and the best estimated values of activity concentrations of 238 U, 234 U, 234 Th, 232 Th, 230 Th, 226 Ra, 210 Pb, 210 Po, 137 Cs in soil were used. Both approaches revealed the highest contribution to the internal dose rate due to 226 Ra and 210 Po, while 137 Cs contributed the most to the external dose rate. In the investigated area total dose rate to biota derived using ERICA Tool ranged from 0.3 to 14.4 μGy h -1 . The natural radionuclides exhibited significantly higher contribution to the total dose rate than the artificial one. In the investigated area, only dose rate for lichens and bryophytes exceeded ERICA Tool screening value of total dose rate of 10 μGy h -1 suggested as confident that environmental risks are negligible. The assessed total dose rates for reference animals and plants using RESRAD BIOTA were found to be 7 and 3 μGy h -1 , respectively. In RESRAD BIOTA - Level 3, 10 species (Lumbricus terrestris, Rana lessonae, Sciurus vulgaris, Anas platyrhynchos, Lepus europaeus, Vulpes vulpes, Capreolus capreolus, Suss crofa, Quercu srobur, Tilia spp.) representative for the study area were modeled. Among them the highest total dose rate (4.5 μGy h -1 ) was obtained for large mammals. Differences in the predicted dose rates to biota using the two software programs are the consequence of the difference in the values of transfer parameters used to calculate activity concentrations in biota. Doses of ionizing radiation estimated in this study will not exhibit deterministic effects at the population level. Thus, the obtained results indicate no significant radiation impact of coal fired power plant operation on terrestrial biota. This paper confirms the use ERICA Tool and RESRAD BIOTA softwares as flexible and effective means of radiation impact assessment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risk analysis in cohort studies with heterogeneous strata. A global chi2-test for dose-response relationship, generalizing the Mantel-Haenszel procedure.

PubMed

Ahlborn, W; Tuz, H J; Uberla, K

1990-03-01

In cohort studies the Mantel-Haenszel estimator ORMH is computed from sample data and is used as a point estimator of relative risk. Test-based confidence intervals are estimated with the help of the asymptotic chi-squared distributed MH-statistic chi 2MHS. The Mantel-extension-chi-squared is used as a test statistic for a dose-response relationship. Both test statistics--the Mantel-Haenszel-chi as well as the Mantel-extension-chi--assume homogeneity of risk across strata, which is rarely present. Also an extended nonparametric statistic, proposed by Terpstra, which is based on the Mann-Whitney-statistics assumes homogeneity of risk across strata. We have earlier defined four risk measures RRkj (k = 1,2,...,4) in the population and considered their estimates and the corresponding asymptotic distributions. In order to overcome the homogeneity assumption we use the delta-method to get "test-based" confidence intervals. Because the four risk measures RRkj are presented as functions of four weights gik we give, consequently, the asymptotic variances of these risk estimators also as functions of the weights gik in a closed form. Approximations to these variances are given. For testing a dose-response relationship we propose a new class of chi 2(1)-distributed global measures Gk and the corresponding global chi 2-test. In contrast to the Mantel-extension-chi homogeneity of risk across strata must not be assumed. These global test statistics are of the Wald type for composite hypotheses.(ABSTRACT TRUNCATED AT 250 WORDS)

[Genetic effects in the liquidators of consequences of Chernobyl Nuclear Power Plant accident].

PubMed

Liaginskaia, A M; Tukov, A R; Osipov, V A; Prokhorova, O N

2007-01-01

The purpose of the present research was the estimation of probable genetic consequences at the liquidators of the consequences of Chernobyl accident in 1986-1987. The research is made on two groups of the liquidators. The first group included the liquidators taking place on the account in the branch register and working now at the enterprises of a nuclear industry. The second group included 902 liquidators of consequences of Chernobyl accident in 1986 constantly living in the Ryazan area and which are taking place on permanent observation the account in regional hospital. For an estimation of probable genetic effects analyzed the data on frequency and outcomes pregnancy of the wives of the liquidators, on condition and on diseases of newborn, on switching intrauterine development defects (IDD). The analysis carried out depending on dozes of an irradiation: up to 5 cGy; 5-10 cGy and 10-25 cGy. Received materials testify, that at the liquidators, at a doze of an external irradiation 10-25 cGy, the determined effects--period long sterility, kept at a part them till 3 years come to light. The set of the received data, such as depending from the dose increase of frequency of spontaneous abortions and of inherent defects of development of newborn, the increase of frequency diseases of newborn and share newborn with low weight, allows to make a conclusion about an induction of genetic effects in sexual cells of the liquidators of consequences of Chernobyl accident at dozes of an external irradiation more than 10 cGy. Taking into account high biological efficiency of alpha-radiation (K = 20), and of beta-radiation (K = 2-4), the equivalent effective doze male gonads (testes) in 3-5 times is higher, than estimated only from external gamma-radiation.

In vivo urethral dose measurements: a method to verify high dose rate prostate treatments.

PubMed

Brezovich, I A; Duan, J; Pareek, P N; Fiveash, J; Ezekiel, M

2000-10-01

Radiation doses delivered in high dose rate (HDR) brachytherapy are susceptible to many inaccuracies and errors, including imaging, planning and delivery. Consequently, the dose delivered to the patient may deviate substantially from the treatment plan. We investigated the feasibility of using TLD measurements in the urethra to estimate the discrepancy in treatments for prostate cancer. The dose response of the 1 mm diam, 6 mm long LiF rods that we used for the in vivo measurements was calibrated with the 192Ir HDR source, as well as a 60Co teletherapy unit. A train of 20 rods contained in a sterile plastic tube was inserted into the urethral (Foley) catheter for the duration of a treatment fraction, and the measured doses were compared to the treatment plan. Initial results from a total of seven treatments in four patients show good agreement between theory and experiment. Analysis of any one treatment showed agreement within 11.7% +/- 6.2% for the highest dose encountered in the central prostatic urethra, and within 10.4% +/- 4.4% for the mean dose. Taking the average over all seven treatments shows agreement within 1.7% for the maximum urethral dose, and within 1.5% for the mean urethral dose. Based on these initial findings it seems that planned prostate doses can be accurately reproduced in the clinic.

The influence of bone density on the radiotherapy of cervix cancer

NASA Astrophysics Data System (ADS)

Soares, M. R.; Souza, D. N.

2011-10-01

Until the 1970s the irradiated region of a patient undergoing external beam radiotherapy was considered a homogeneous volume and a regular surface, with physical characteristics similar to water. With the improvement of medical imaging equipment, it has become possible to conduct planning in radiotherapy treatment that considers the heterogeneities and irregularities of a patient's anatomy. Consequently, such technological resources have brought greater accuracy to radiotherapy. In this study, we determined the variation in the average amount of absorbed dose on the target volume and at the point of prescription treatment by comparing the doses which were calculated in a planning system considering the patient both as a homogeneous, and as a heterogeneous medium. The results showed that when we take into account the volume of the upper vagina and cervix, and consider the pelvis as a heterogeneous medium, the calculated dose was under-estimated at some points in the studied volume with respect to the dose when this region was considered homogeneous.

Offsite radiological consequence analysis for the bounding flammable gas accident

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

CARRO, C.A.

2003-03-19

The purpose of this analysis is to calculate the offsite radiological consequence of the bounding flammable gas accident. DOE-STD-3009-94, ''Preparation Guide for U.S. Department of Energy Nonreactor Nuclear Facility Documented Safety Analyses'', requires the formal quantification of a limited subset of accidents representing a complete set of bounding conditions. The results of these analyses are then evaluated to determine if they challenge the DOE-STD-3009-94, Appendix A, ''Evaluation Guideline,'' of 25 rem total effective dose equivalent in order to identify and evaluate safety class structures, systems, and components. The bounding flammable gas accident is a detonation in a single-shell tank (SST).more » A detonation versus a deflagration was selected for analysis because the faster flame speed of a detonation can potentially result in a larger release of respirable material. As will be shown, the consequences of a detonation in either an SST or a double-shell tank (DST) are approximately equal. A detonation in an SST was selected as the bounding condition because the estimated respirable release masses are the same and because the doses per unit quantity of waste inhaled are generally greater for SSTs than for DSTs. Appendix A contains a DST analysis for comparison purposes.« less

TH-AB-207A-01: Contrast-Enhanced CT: Correlation of Radiation Dose and Biological Effect

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

Abadi, E; Sanders, J; Agasthya, G

2016-06-15

Purpose: The potential risk from CT is generally characterized in terms of radiation dose. The presence of iodinated-contrast medium increases radiation dose. However, it is unclear how much of this increase is biologically relevant. The purpose of this study was to establish the contribution of dose increase from iodine to biological effect. Methods: Radiation organ dose was estimated in 58 human (XCAT) phantoms “undergoing” chest CT examination (120 kVp, 9 mGy CTDI) on a simulated CT system (Definition Flash, Siemens) with and without iodinated-contrast agent (62.5 mL of iodine per subject). The dose without and with the presence of iodinemore » was compared to the increase in foci per cell (a surrogate of DNA damage) measured before and after similar CT exams without and with contrast agent (Piechowiak et al. 2015). The data were analyzed to ascertain how the enhancement in biological effect in contrast-enhanced CTs correlated with the increase in dose due to the presence of iodine. Results: The presence of iodinated-contrast in CT increased the organ doses by 2% to 50% on average. Typical values were heart (50%±7%), kidney (19%±7%), and liver (2%±3%). The corresponding increase in the average foci per cell was 107%±19%, indicating biological effect of iodine was greater than what would be anticipated from the iodine-initiated increase in radiation dose alone. Conclusion: Mean foci per cell and organ dose both increase in the presence of contrast agent. The former, however, is at least twice as large as the latter, indicating that iodine contributes to an increase in the probability of DNA damage not only as a consequence of increased x-ray energy deposition but also from other mechanisms. Hence iodine radiation dose, while relevant to be included in estimating the risk associated with contrast-enhanced CT, still can underestimate the biological effects.« less

Human exposure and internal dose assessments of acrylamide in food.

PubMed

Dybing, E; Farmer, P B; Andersen, M; Fennell, T R; Lalljie, S P D; Müller, D J G; Olin, S; Petersen, B J; Schlatter, J; Scholz, G; Scimeca, J A; Slimani, N; Törnqvist, M; Tuijtelaars, S; Verger, P

2005-03-01

This review provides a framework contributing to the risk assessment of acrylamide in food. It is based on the outcome of the ILSI Europe FOSIE process, a risk assessment framework for chemicals in foods and adds to the overall framework by focusing especially on exposure assessment and internal dose assessment of acrylamide in food. Since the finding that acrylamide is formed in food during heat processing and preparation of food, much effort has been (and still is being) put into understanding its mechanism of formation, on developing analytical methods and determination of levels in food, and on evaluation of its toxicity and potential toxicity and potential human health consequences. Although several exposure estimations have been proposed, a systematic review of key information relevant to exposure assessment is currently lacking. The European and North American branches of the International Life Sciences Institute, ILSI, discussed critical aspects of exposure assessment, parameters influencing the outcome of exposure assessment and summarised data relevant to the acrylamide exposure assessment to aid the risk characterisation process. This paper reviews the data on acrylamide levels in food including its formation and analytical methods, the determination of human consumption patterns, dietary intake of the general population, estimation of maximum intake levels and identification of groups of potentially high intakes. Possible options and consequences of mitigation efforts to reduce exposure are discussed. Furthermore the association of intake levels with biomarkers of exposure and internal dose, considering aspects of bioavailability, is reviewed, and a physiologically-based toxicokinetic (PBTK) model is described that provides a good description of the kinetics of acrylamide in the rat. Each of the sections concludes with a summary of remaining gaps and uncertainties.

Effects of incomplete residential histories on studies of environmental exposure with application to childhood leukaemia and background radiation.

PubMed

Nikkilä, Atte; Kendall, Gerald; Raitanen, Jani; Spycher, Ben; Lohi, Olli; Auvinen, Anssi

2018-06-22

When evaluating environmental exposures, residential exposures are often most relevant. In most countries, it is impossible to establish full residential histories. In recent publications, childhood leukaemia and background radiation have been studied with and without full residential histories. This paper investigates the consequences of lacking such full data. Data from a nationwide Finnish Case-Control study of Childhood Leukaemia and gamma rays were analysed. This included 1093 children diagnosed with leukaemia in Finland in 1990-2011. Each case was matched by gender and year of birth to three controls. Full residential histories were available. The dose estimates were based on outdoor background radiation measurements. The indoor dose rates were obtained with a dwelling type specific conversion coefficient and the individual time-weighted mean red bone marrow dose rates were calculated using age-specific indoor occupancy and the age and gender of the child. Radiation from Chernobyl fallout was included and a 2-year latency period assumed. The median separation between successive dwellings was 3.4 km and median difference in red bone marrow dose 2.9 nSv/h. The Pearson correlation between the indoor red bone marrow dose rates of successive dwellings was 0.62 (95% CI 0.60, 0.64). The odds ratio for a 10 nSv/h increase in dose rate with full residential histories was 1.01 (95% CI 0.97, 1.05). Similar odds ratios were calculated with dose rates based on only the first dwelling (1.02, 95% CI 0.99, 1.05) and only the last dwelling (1.00, 95% CI 0.98, 1.03) and for subjects who had lived only in a single dwelling (1.05, 95% CI 0.98, 1.10). Knowledge of full residential histories would always be the option of choice. However, due to the strong correlation between exposure estimates in successive dwellings and the uncertainty about the most relevant exposure period, estimation of overall exposure level from a single address is also informative. Error in dose estimation is likely to cause some degree of classical measurement error resulting in bias towards the null. Copyright © 2018 Elsevier Inc. All rights reserved.

Radon induced hyperplasia: effective adaptation reducing the local doses in the bronchial epithelium.

PubMed

Madas, Balázs G

2016-09-01

There is experimental and histological evidence that chronic irritation and cell death may cause hyperplasia in the exposed tissue. As the heterogeneous deposition of inhaled radon progeny results in high local doses at the peak of the bronchial bifurcations, it was proposed earlier that hyperplasia occurs in these deposition hot spots upon chronic radon exposure. The objective of the present study is to quantify how the induction of basal cell hyperplasia modulates the microdosimetric consequences of a given radon exposure. For this purpose, computational epithelium models were constructed with spherical cell nuclei of six different cell types based on histological data. Basal cell hyperplasia was modelled by epithelium models with additional basal cells and increased epithelium thickness. Microdosimetry for alpha-particles was performed by an own-developed Monte-Carlo code. Results show that the average tissue dose, and the average hit number and dose of basal cells decrease by the increase of the measure of hyperplasia. Hit and dose distribution reveal that the induction of hyperplasia may result in a basal cell pool which is shielded from alpha-radiation. It highlights that the exposure history affects the microdosimetric consequences of a present exposure, while the biological and health effects may also depend on previous exposures. The induction of hyperplasia can be considered as a radioadaptive response at the tissue level. Such an adaptation of the tissue challenges the validity of the application of the dose and dose rate effectiveness factor from a mechanistic point of view. As the location of radiosensitive target cells may change due to previous exposures, dosimetry models considering the tissue geometry characteristic of normal conditions may be inappropriate for dose estimation in case of protracted exposures. As internal exposures are frequently chronic, such changes in tissue geometry may be highly relevant for other incorporated radionuclides.

[Medical and biological consequences of nuclear disasters].

PubMed

Stalpers, Lukas J A; van Dullemen, Simon; Franken, N A P Klaas

2012-01-01

Medical risks of radiation exaggerated; psychological risks underestimated. The discussion about atomic energy has become topical again following the nuclear accident in Fukushima. There is some argument about the gravity of medical and biological consequences of prolonged exposure to radiation. The risk of cancer following a low dose of radiation is usually estimated by linear extrapolation of the incidence of cancer among survivors of the atomic bombs dropped on Hiroshima and Nagasaki in 1945. The radiobiological linear-quadratic model (LQ-model) gives a more accurate description of observed data, is radiobiologically more plausible and is better supported by experimental and clinical data. On the basis of this model there is less risk of cancer being induced following radiation exposure. The gravest consequence of Chernobyl and Fukushima is not the medical and biological damage, but the psychological and economical impact on rescue workers and former inhabitants.

Evaluation of human body irradiation caused by radionuclides deposited in the filtration unit of gas mask.

PubMed

Cerny, R; Johnova, K; Otahal, P; Thinova, L; Kluson, J

2017-12-01

Radioactive aerosol particles represent a serious risk for people facing the consequences of nuclear accident of any kind. The first responders to emergency situation need to be protected by personal protective equipment which includes radiation protection suit supplemented with gas mask. The purpose of this work is to estimate the dose to the organs of responder's body as a result of radionuclide deposition in the filtration unit of the gas mask. The problem was analyzed using Monte Carlo simulations. The dose absorbed by different organs for five representative radionuclides and the dose distribution over the responder's body are presented in this paper. Based on presented MC simulations, we suggest a method of evaluating the irradiation of the responder by the radionuclides deposited in the filtration unit of the gas mask. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

MIRD Pamphlet No. 23: Quantitative SPECT for Patient-Specific 3-Dimensional Dosimetry in Internal Radionuclide Therapy

PubMed Central

Dewaraja, Yuni K.; Frey, Eric C.; Sgouros, George; Brill, A. Bertrand; Roberson, Peter; Zanzonico, Pat B.; Ljungberg, Michael

2012-01-01

In internal radionuclide therapy, a growing interest in voxel-level estimates of tissue-absorbed dose has been driven by the desire to report radiobiologic quantities that account for the biologic consequences of both spatial and temporal nonuniformities in these dose estimates. This report presents an overview of 3-dimensional SPECT methods and requirements for internal dosimetry at both regional and voxel levels. Combined SPECT/CT image-based methods are emphasized, because the CT-derived anatomic information allows one to address multiple technical factors that affect SPECT quantification while facilitating the patient-specific voxel-level dosimetry calculation itself. SPECT imaging and reconstruction techniques for quantification in radionuclide therapy are not necessarily the same as those designed to optimize diagnostic imaging quality. The current overview is intended as an introduction to an upcoming series of MIRD pamphlets with detailed radionuclide-specific recommendations intended to provide best-practice SPECT quantification–based guidance for radionuclide dosimetry. PMID:22743252

Indoor and outdoor radon measurements at lung cancer patients' homes in the dwellings of Rize Province in Turkey.

PubMed

Özen, Songül Akbulut; Celik, Necati; Dursun, Emrehan; Taskın, Halim

2018-06-01

In this study, indoor and outdoor radon ( 222 Rn) surveys were carried out in the summer and winter seasons in homes of one hundred lung cancer patients in the year 2013-2014. The aim was to investigate the relationship between radon and cancer patients. Lung cancer patients completed a questionnaire concerning their living environment, various physical parameters and living habits. Pearson correlation and t tests revealed no meaningful results between radon concentrations, on one hand, and environmental and personal living habits, on the other hand. Consequently, the BEIR VI model was adapted and 222 Rn exposure was estimated to be responsible for about 12% of the lung cancer incidences in the winter season and around 5% in the summer season in the Rize Province. However, due to the limited number of data and numerous parameters that could lead to lung cancer, the estimations done with the model should be taken very lightly. The annual effective doses due to inhalation of indoor and outdoor 222 Rn were estimated to be, respectively, 1.43 and 0.94 mSv y -1 . The indoor and outdoor annual effective doses were, respectively, close and below the world annual effective dose (1.3 mSv y -1 ). At the district level, the indoor annual effective dose equivalent in the İyidere district was 4.52 mSv y -1 , which was 3.5 times greater than the world average. The number of patients in the majority of the houses in this district was more than one.

Reduction of the estimated radiation dose and associated patient risk with prospective ECG-gated 256-slice CT coronary angiography

NASA Astrophysics Data System (ADS)

Efstathopoulos, E. P.; Kelekis, N. L.; Pantos, I.; Brountzos, E.; Argentos, S.; Grebáč, J.; Ziaka, D.; Katritsis, D. G.; Seimenis, I.

2009-09-01

Computed tomography (CT) coronary angiography has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but high radiation doses have been reported. Prospective ECG-gating using a 'step-and-shoot' axial scanning protocol has been shown to reduce radiation exposure effectively while maintaining diagnostic accuracy. 256-slice scanners with 80 mm detector coverage have been currently introduced into practice, but their impact on radiation exposure has not been adequately studied. The aim of this study was to assess radiation doses associated with CT coronary angiography using a 256-slice CT scanner. Radiation doses were estimated for 25 patients scanned with either prospective or retrospective ECG-gating. Image quality was assessed objectively in terms of mean CT attenuation at selected regions of interest on axial coronary images and subjectively by coronary segment quality scoring. It was found that radiation doses associated with prospective ECG-gating were significantly lower than retrospective ECG-gating (3.2 ± 0.6 mSv versus 13.4 ± 2.7 mSv). Consequently, the radiogenic fatal cancer risk for the patient is much lower with prospective gating (0.0176% versus 0.0737%). No statistically significant differences in image quality were observed between the two scanning protocols for both objective and subjective quality assessments. Therefore, prospective ECG-gating using a 'step-and-shoot' protocol that covers the cardiac anatomy in two axial acquisitions effectively reduces radiation doses in 256-slice CT coronary angiography without compromising image quality.

Feasibility study of veterinary antibiotic consumption in Germany--comparison of ADDs and UDDs by animal production type, antimicrobial class and indication.

PubMed

Merle, Roswitha; Robanus, Matthias; Hegger-Gravenhorst, Christine; Mollenhauer, Yvonne; Hajek, Peter; Käsbohrer, Annemarie; Honscha, Walther; Kreienbrock, Lothar

2014-01-08

Within a feasibility study the use of antibiotics in pigs and cattle was determined in 24 veterinary practices in Lower Saxony and on 66 farms in North Rhine-Westphalia in Germany. Focus was laid on the comparison of the Used Daily Doses (UDD) (dose per animal and day prescribed by the veterinarians) with the Defined Animal Daily Doses (ADD) (dose per animal and day calculated by means of recommended dosages and estimated live weights). For piglets and calves most of the UDD (50% and 46% of nUDD, respectively) were above the ADD (i.e. UDD/ADD-ratio above 1.25). Regarding sows, fattening pigs, dairy and beef cattle, most of the UDDs (49% to 65% of nUDD) were lower than the respective ADD (i.e. UDD/ADD-ratio below 0.8). In pigs, the UDDs of beta-lactams, fluoroquinolones and cephalosporins, and in cattle, those of macrolides and beta-lactams were often below the ADDs. Tetracyclines were frequently used above the recommended dose.Enteric diseases were more often treated below the recommended dose than respiratory diseases, possibly due to overestimation of the live weight (diarrhea in young animals, respiratory diseases in elder animals) and consequently overestimation of the recommended dose. Comparisons between UDD and ADD can be used to observe differences between antimicrobials and trends in the usage of antibiotics. But individual treatment comparisons of UDD and ADD must be interpreted carefully, because they may be due to lower live weights than estimated. Correlating such data with data on the occurrence of resistant bacteria in future may help to improve resistance prevention and control.

Feasibility study of veterinary antibiotic consumption in Germany - comparison of ADDs and UDDs by animal production type, antimicrobial class and indication

PubMed Central

2014-01-01

Background Within a feasibility study the use of antibiotics in pigs and cattle was determined in 24 veterinary practices in Lower Saxony and on 66 farms in North Rhine-Westphalia in Germany. Focus was laid on the comparison of the Used Daily Doses (UDD) (dose per animal and day prescribed by the veterinarians) with the Defined Animal Daily Doses (ADD) (dose per animal and day calculated by means of recommended dosages and estimated live weights). Results For piglets and calves most of the UDD (50% and 46% of nUDD, respectively) were above the ADD (i.e. UDD/ADD-ratio above 1.25). Regarding sows, fattening pigs, dairy and beef cattle, most of the UDDs (49% to 65% of nUDD) were lower than the respective ADD (i.e. UDD/ADD-ratio below 0.8). In pigs, the UDDs of beta-lactams, fluoroquinolones and cephalosporins, and in cattle, those of macrolides and beta-lactams were often below the ADDs. Tetracyclines were frequently used above the recommended dose. Enteric diseases were more often treated below the recommended dose than respiratory diseases, possibly due to overestimation of the live weight (diarrhea in young animals, respiratory diseases in elder animals) and consequently overestimation of the recommended dose. Conclusion Comparisons between UDD and ADD can be used to observe differences between antimicrobials and trends in the usage of antibiotics. But individual treatment comparisons of UDD and ADD must be interpreted carefully, because they may be due to lower live weights than estimated. Correlating such data with data on the occurrence of resistant bacteria in future may help to improve resistance prevention and control. PMID:24401194

Savings from the use of a probiotic formula in the prophylaxis of antibiotic-associated diarrhea.

PubMed

Kamdeu Fansi, Alvine Adrienne; Guertin, Jason Robert; LeLorier, Jacques

2012-01-01

Antibiotic-associated diarrhea (AAD) and particularly Clostridium difficile-associated diarrhea (CDAD) are the most common causes of healthcare associated infectious diarrhea. A double-blind, dose response, placebo-controlled trial of the probiotic formula (Bio-K+ Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R formula) for prophylaxis of AAD and CDAD was published in 2010. The Bio-K+ Lactobacillus acidophilus CL1285 and Lactobacillus casei LBC80R formula is a registered trademark of Bio-K Plus International Inc. (Laval, Québec, Canada). Results indicated that the incidence of AAD and CDAD were lower for patients assigned to the probiotic formula compared with the placebo option. The present study aims to estimate the savings in direct medical costs that might result from the use of two different doses of the probiotic formula vs placebo. A cost-consequence analysis was conducted to compare the two doses of the probiotic formula compared to placebo. The analysis was based upon published data and adjusted to the North American context. Economic analyses showed that the use of the probiotic formula would result in estimated mean per patients savings of US$1968 for the single dose and US$2661 for the double dose compared with the placebo option if used an average of 13 days by all patients at risk of developing AAD and CDAD. Several key parameters considered within the economic model were not captured within the Gao et al. study. Numerous sensitivity analyses were conducted to address this issue. The use of the probiotic formula in prophylaxis of AAD and CDAD would lead to estimated savings in direct medical costs that would substantially offset its acquisition cost. Treating 1000 hospitalized patients on antibiotics with the double dose of the product compared to current practice would save a single payer system the sum of $2,661,218.

A highly infective plant-associated bacterium influences reproductive rates in pea aphids

PubMed Central

Hendry, Tory A.; Clark, Kelley J.; Baltrus, David A.

2016-01-01

Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction. PMID:26998321

A highly infective plant-associated bacterium influences reproductive rates in pea aphids.

PubMed

Hendry, Tory A; Clark, Kelley J; Baltrus, David A

2016-02-01

Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction.

Evaluation of effective dose with chest digital tomosynthesis system using Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Kim, Dohyeon; Jo, Byungdu; Lee, Youngjin; Park, Su-Jin; Lee, Dong-Hoon; Kim, Hee-Joung

2015-03-01

Chest digital tomosynthesis (CDT) system has recently been introduced and studied. This system offers the potential to be a substantial improvement over conventional chest radiography for the lung nodule detection and reduces the radiation dose with limited angles. PC-based Monte Carlo program (PCXMC) simulation toolkit (STUK, Helsinki, Finland) is widely used to evaluate radiation dose in CDT system. However, this toolkit has two significant limits. Although PCXMC is not possible to describe a model for every individual patient and does not describe the accurate X-ray beam spectrum, Geant4 Application for Tomographic Emission (GATE) simulation describes the various size of phantom for individual patient and proper X-ray spectrum. However, few studies have been conducted to evaluate effective dose in CDT system with the Monte Carlo simulation toolkit using GATE. The purpose of this study was to evaluate effective dose in virtual infant chest phantom of posterior-anterior (PA) view in CDT system using GATE simulation. We obtained the effective dose at different tube angles by applying dose actor function in GATE simulation which was commonly used to obtain the medical radiation dosimetry. The results indicated that GATE simulation was useful to estimate distribution of absorbed dose. Consequently, we obtained the acceptable distribution of effective dose at each projection. These results indicated that GATE simulation can be alternative method of calculating effective dose in CDT applications.

[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.

The Effect of Ingested Glucose Dose on the Suppression of Endogenous Glucose Production in Humans.

PubMed

Kowalski, Greg M; Moore, Samantha M; Hamley, Steven; Selathurai, Ahrathy; Bruce, Clinton R

2017-09-01

Insulin clamp studies have shown that the suppressive actions of insulin on endogenous glucose production (EGP) are markedly more sensitive than for stimulating glucose disposal ( R d ). However, clamp conditions do not adequately mimic postprandial physiological responses. Here, using the variable infusion dual-tracer approach, we used a threefold range of ingested glucose doses (25, 50, and 75 g) to investigate how physiological changes in plasma insulin influence EGP in healthy subjects. Remarkably, the glucose responses were similar for all doses tested, yet there was a dose-dependent increase in insulin secretion and plasma insulin levels. Nonetheless, EGP was suppressed with the same rapidity and magnitude (∼55%) across all doses. The progressive hyperinsulinemia, however, caused a dose-dependent increase in the estimated rates of R d , which likely accounts for the lack of a dose effect on plasma glucose excursions. This suggests that after glucose ingestion, the body preferentially permits a transient and optimal degree of postprandial hyperglycemia to efficiently enhance insulin-induced changes in glucose fluxes, thereby minimizing the demand for insulin secretion. This may represent an evolutionarily conserved mechanism that not only reduces the secretory burden on β-cells but also avoids the potential negative consequences of excessive insulin release into the systemic arterial circulation. © 2017 by the American Diabetes Association.

Analytical probabilistic proton dose calculation and range uncertainties

NASA Astrophysics Data System (ADS)

Bangert, M.; Hennig, P.; Oelfke, U.

2014-03-01

We introduce the concept of analytical probabilistic modeling (APM) to calculate the mean and the standard deviation of intensity-modulated proton dose distributions under the influence of range uncertainties in closed form. For APM, range uncertainties are modeled with a multivariate Normal distribution p(z) over the radiological depths z. A pencil beam algorithm that parameterizes the proton depth dose d(z) with a weighted superposition of ten Gaussians is used. Hence, the integrals ∫ dz p(z) d(z) and ∫ dz p(z) d(z)2 required for the calculation of the expected value and standard deviation of the dose remain analytically tractable and can be efficiently evaluated. The means μk, widths δk, and weights ωk of the Gaussian components parameterizing the depth dose curves are found with least squares fits for all available proton ranges. We observe less than 0.3% average deviation of the Gaussian parameterizations from the original proton depth dose curves. Consequently, APM yields high accuracy estimates for the expected value and standard deviation of intensity-modulated proton dose distributions for two dimensional test cases. APM can accommodate arbitrary correlation models and account for the different nature of random and systematic errors in fractionated radiation therapy. Beneficial applications of APM in robust planning are feasible.

Retrospective dosimetry of Iodine-131 exposures using Iodine-129 and Caesium-137 inventories in soils--A critical evaluation of the consequences of the Chernobyl accident in parts of Northern Ukraine.

PubMed

Michel, R; Daraoui, A; Gorny, M; Jakob, D; Sachse, R; Romantschuk, L D; Alfimov, V; Synal, H-A

2015-12-01

The radiation exposure of thyroid glands due to (131)I as a consequence of the Chernobyl accident was investigated retrospectively based on (129)I and (137)Cs inventories in soils in Northern Ukraine. To this end, soil samples from 60 settlements were investigated for (129)I, (127)I, and (137)Cs by AMS, ICP-MS and gamma-spectrometry, respectively. Sampling was performed between 2004 und 2007. In those parts of Northern Ukraine investigated here the (129)I and (137)Cs inventories are well correlated, the variability of the individual (129)I/(137)Cs ratios being, however, high. Both the (129)I and (137)Cs inventories in the individual 5 samples for each settlement allowed estimating the uncertainties of the inventories due to the variability of the radionuclide deposition and consequently of the retrospective dosimetry. Thyroid equivalent doses were calculated from the (129)I and the (137)Cs inventories using aggregated dose coefficients for 5-year old and 10-year-old children as well as for adults. The highest thyroid equivalent doses (calculated from (129)I inventories) were calculated for Wladimirowka with 30 Gy for 5-years-old children and 7 Gy for adults. In 35 settlements of contamination zone II the geometric mean of the thyroid equivalent doses was 2.0 Gy for 5-years-old children with a geometric standard deviation (GSD) of 3.0. For adults the geometric mean was 0.47 Gy also with a GSD of 3.0. In more than 25 settlements of contamination zone III the geometric means were 0.82 Gy for 5-years old children with a GSD of 1.8 and 0.21 Gy for adults (GSD 1.8). For 45 settlements, the results of the retrospective dosimetry could be compared with thyroid equivalent doses calculated using time-integrated (131)I activities of thyroids which were measured in 1986. Thus, a critical evaluation of the results was possible which demonstrated the general feasibility of the method, but also the associated uncertainties and limitations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Genomic instability, bystander effect, cytoplasmic irradiation and other phenomena that may achieve fame without fortune.

PubMed

Hall, E J

2001-01-01

The possible risk of induced malignancies in astronauts, as a consequence of the radiation environment in space, is a factor of concern for long term missions. Cancer risk estimates for high doses of low LET radiation are available from the epidemiological studies of the A-bomb survivors. Cancer risks at lower doses cannot be detected in epidemiological studies and must be inferred by extrapolation from the high dose risks. The standard setting bodies, such as the ICRP recommend a linear, no-threshold extrapolation of risks from high to low doses, but this is controversial. A study of mechanisms of carcinogenesis may shed some light on the validity of a linear extrapolation. The multi-step nature of carcinogenesis suggests that the role of radiation may be to induce a mutation leading to a mutator phenotype. High energy Fe ions, such as those encountered in space are highly effective in inducing genomic instability. Experiments involving the single particle microbeam have demonstrated a "bystander effect", ie a biological effect in cells not themselves hit, but in close proximity to those that are, as well as the induction of mutations in cells where only the cytoplasm, and not the nucleus, have been traversed by a charged particle. These recent experiments cast doubt on the validity of a simple linear extrapolation, but the data are so far fragmentary and conflicting. More studies are necessary. While mechanistic studies cannot replace epidemiology as a source of quantitative risk estimates, they may shed some light on the shape of the dose response relationship and therefore on the limitations of a linear extrapolation to low doses.

Genomic instability, bystander effect, cytoplasmic irradiation and other phenomena that may achieve fame without fortune

NASA Technical Reports Server (NTRS)

Hall, E. J.

2001-01-01

The possible risk of induced malignancies in astronauts, as a consequence of the radiation environment in space, is a factor of concern for long term missions. Cancer risk estimates for high doses of low LET radiation are available from the epidemiological studies of the A-bomb survivors. Cancer risks at lower doses cannot be detected in epidemiological studies and must be inferred by extrapolation from the high dose risks. The standard setting bodies, such as the ICRP recommend a linear, no-threshold extrapolation of risks from high to low doses, but this is controversial. A study of mechanisms of carcinogenesis may shed some light on the validity of a linear extrapolation. The multi-step nature of carcinogenesis suggests that the role of radiation may be to induce a mutation leading to a mutator phenotype. High energy Fe ions, such as those encountered in space are highly effective in inducing genomic instability. Experiments involving the single particle microbeam have demonstrated a "bystander effect", ie a biological effect in cells not themselves hit, but in close proximity to those that are, as well as the induction of mutations in cells where only the cytoplasm, and not the nucleus, have been traversed by a charged particle. These recent experiments cast doubt on the validity of a simple linear extrapolation, but the data are so far fragmentary and conflicting. More studies are necessary. While mechanistic studies cannot replace epidemiology as a source of quantitative risk estimates, they may shed some light on the shape of the dose response relationship and therefore on the limitations of a linear extrapolation to low doses.

The polonium-210 poisoning of Mr Alexander Litvinenko

DOE PAGES

Harrison, John; Fell, Tim; Leggett, Rich; ...

2017-02-28

Mr Litvinenko died on 23rd November 2006 after having been poisoned with polonium-210 on 1st November. Measurements of the polonium-210 content of post-mortem tissue samples and samples of urine and blood showed the presence of large amounts of 210Po. Furthermore, autoradiography of hair samples showed two regions of 210Po activity, providing evidence of an earlier poisoning attempt during October 2006, resulting in absorption to blood of about one-hundredth of that estimated for 1st November. Intake by ingestion on 1st November was estimated to be around 4 GBq, assuming 10% absorption to blood, and the resulting organ doses reached estimatedmore » values that were generally in a range from about 20 Gy to over 100 Gy. In comparison with estimates of protracted alpha particle the doses required to cause irreversible organ damage support the conclusion that death was the inevitable consequence of multiple organ failure, with destruction of the haemopoietic bone marrow, as well as damage to kidneys and liver, being important contributors. If the earlier poisoning during October 2006 had not been followed by a second major intake on 1st November, it is possible that the earlier intake of around 40 MBq, with absorption of 4 MBq to blood, might have proved fatal over a prolonged period of months or years, primarily as a result of kidney damage following a dose of approaching 3 Gy.« less

The polonium-210 poisoning of Mr Alexander Litvinenko

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

Harrison, John; Fell, Tim; Leggett, Rich

Mr Litvinenko died on 23rd November 2006 after having been poisoned with polonium-210 on 1st November. Measurements of the polonium-210 content of post-mortem tissue samples and samples of urine and blood showed the presence of large amounts of 210Po. Furthermore, autoradiography of hair samples showed two regions of 210Po activity, providing evidence of an earlier poisoning attempt during October 2006, resulting in absorption to blood of about one-hundredth of that estimated for 1st November. Intake by ingestion on 1st November was estimated to be around 4 GBq, assuming 10% absorption to blood, and the resulting organ doses reached estimatedmore » values that were generally in a range from about 20 Gy to over 100 Gy. In comparison with estimates of protracted alpha particle the doses required to cause irreversible organ damage support the conclusion that death was the inevitable consequence of multiple organ failure, with destruction of the haemopoietic bone marrow, as well as damage to kidneys and liver, being important contributors. If the earlier poisoning during October 2006 had not been followed by a second major intake on 1st November, it is possible that the earlier intake of around 40 MBq, with absorption of 4 MBq to blood, might have proved fatal over a prolonged period of months or years, primarily as a result of kidney damage following a dose of approaching 3 Gy.« less

Long-term fate of depleted uranium at Aberdeen and Yuma Proving Grounds: Human health and ecological risk assessments

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

Ebinger, M.H.; Beckman, R.J.; Myers, O.B.

1996-09-01

The purpose of this study was to evaluate the immediate and long-term consequences of depleted uranium (DU) in the environment at Aberdeen Proving Ground (APG) and Yuma Proving Ground (YPG) for the Test and Evaluation Command (TECOM) of the US Army. Specifically, we examined the potential for adverse radiological and toxicological effects to humans and ecosystems caused by exposure to DU at both installations. We developed contaminant transport models of aquatic and terrestrial ecosystems at APG and terrestrial ecosystems at YPG to assess potential adverse effects from DU exposure. Sensitivity and uncertainty analyses of the initial models showed the portionsmore » of the models that most influenced predicted DU concentrations, and the results of the sensitivity analyses were fundamental tools in designing field sampling campaigns at both installations. Results of uranium (U) isotope analyses of field samples provided data to evaluate the source of U in the environment and the toxicological and radiological doses to different ecosystem components and to humans. Probabilistic doses were estimated from the field data, and DU was identified in several components of the food chain at APG and YPG. Dose estimates from APG data indicated that U or DU uptake was insufficient to cause adverse toxicological or radiological effects. Dose estimates from YPG data indicated that U or DU uptake is insufficient to cause radiological effects in ecosystem components or in humans, but toxicological effects in small mammals (e.g., kangaroo rats and pocket mice) may occur from U or DU ingestion. The results of this study were used to modify environmental radiation monitoring plans at APG and YPG to ensure collection of adequate data for ongoing ecological and human health risk assessments.« less

Chlorine truck attack consequences and mitigation.

PubMed

Barrett, Anthony Michael; Adams, Peter J

2011-08-01

We develop and apply an integrated modeling system to estimate fatalities from intentional release of 17 tons of chlorine from a tank truck in a generic urban area. A public response model specifies locations and actions of the populace. A chemical source term model predicts initial characteristics of the chlorine vapor and aerosol cloud. An atmospheric dispersion model predicts cloud spreading and movement. A building air exchange model simulates movement of chlorine from outdoors into buildings at each location. A dose-response model translates chlorine exposures into predicted fatalities. Important parameters outside defender control include wind speed, atmospheric stability class, amount of chlorine released, and dose-response model parameters. Without fast and effective defense response, with 2.5 m/sec wind and stability class F, we estimate approximately 4,000 (half within ∼10 minutes) to 30,000 fatalities (half within ∼20 minutes), depending on dose-response model. Although we assume 7% of the population was outdoors, they represent 60-90% of fatalities. Changing weather conditions result in approximately 50-90% lower total fatalities. Measures such as sheltering in place, evacuation, and use of security barriers and cryogenic storage can reduce fatalities, sometimes by 50% or more, depending on response speed and other factors. © 2011 Society for Risk Analysis.

Radiation protection recommendations as applied to the disposal of long-lived solid radioactive waste. A report of The International Commission on Radiological Protection.

PubMed

1998-01-01

(79) Waste, by definition, has no benefit. It should be viewed as one aspect of the beneficial practice that gave rise to it. Furthermore, radioactive waste management should be placed in the context of the management of society's waste in general. (80) A major issue in evaluating the acceptability of a disposal system for long-lived solid radioactive waste is that doses or risks may arise from exposures in the distant future. There is uncertainty surrounding any estimate of these doses or risks due to lack of knowledge about future conditions. Such exposures are treated as potential exposures as their magnitude depends on future processes and conditions that have probabilities associated with them. (81) Nevertheless, the Commission recognises a basic principle that individuals and populations in the future should be afforded at least the same level of protection from the action of disposing of radioactive waste today as is the current generation. This implies use of the current quantitative dose and risk criteria derived from considering associated health detriment. Therefore, protection of future generations should be achieved by applying these dose or risk criteria to the estimated future doses or risks in appropriately defined critical groups. These estimates should not be regarded as measures of health detriment beyond times of around several hundreds of years into the future. In the case of these longer time periods, they represent indicators of the protection afforded by the disposal system. (82 Constrained optimisation is the central approach to evaluating the radiological acceptability of a waste disposal system; dose or risk constraints are used rather than dose or risk limits. By this transition from limitation to optimisation, the needs of practical application of the radiological protection system to the disposal of long-lived solid waste disposal are met: determination of acceptability now for exposures that may occur in the distant future. Optimisation should be applied in an iterative manner during the disposal system development process and should particularly cover both site selection and repository design. (83) Two broad categories of exposure situations should be considered: natural processes and human intrusion. The latter only refers to intrusion that is inadvertent. The radiological implications of deliberate intrusion into a repository are the responsibility of the intruder. Assessed doses or risks arising from natural processes should be compared with a dose constraint of 0.3 mSv per year or its risk equivalent of around 10(-5) per year. With regard to human intrusion, the consequences from one or more plausible stylized scenarios should be considered in order to evaluate the resilience of the repository to such events. (84) The Commission considers that in circumstances where human intrusion could lead to doses to those living around the site sufficiently high that intervention on current criteria would almost always be justified, reasonable efforts should be made at the repository development stage to reduce the probability of human intrusion or to limit its consequences. In this respect, the Commission has previously advised that an existing annual dose of around 10 mSv per year may be used as a generic reference level below which intervention is not likely to be justifiable. Conversely, an existing annual dose of around 100 mSv per year may be used as a generic reference level above which intervention should be considered almost always justifiable. Similar considerations apply in situations where the thresholds for deterministic effects in relevant organs are exceeded. (85) Compliance with the constraints can be assessed by utilising either an aggregated risk-oriented approach, with a risk constraint, or a disaggregated dose/probability approach, with a dose constraint, or a combination of both. A similar level of protection can be achieved by any of these approaches; however, more information may

[Study of the consequences to the health of the Urkutsk Region's population from nuclear explosions at the Semipalatinsk testing site].

PubMed

Rukavishnikov, V S; Efimova, N V; Katul'skaia, O Iu; Cherniago, B P; Matorova, N I; Beliaeva, T A; Medvedev, V I

2009-01-01

Analysis of archival records on the activity of diurnal plane-tables from the region's weather stations revealed local radioactive fall-out in the near-Baikal areas from the nuclear weapon tests carried out at the Semipalatinsk testing site. Examination of mortality rates in the settlements exposed to the tests showed that the maximum rates of overall and lung malignancy mortalities were observed in 1960-1979; the mean radiation dose in the exposed settlements were estimated to be 580-850 MeV.

Potential for intensity-modulated radiation therapy to permit dose escalation for canine nasal cancer.

PubMed

Vaudaux, Catherine; Schneider, Uwe; Kaser-Hotz, Barbara

2007-01-01

We evaluated the impact of inverse planned intensity-modulated radiation therapy (IMRT) on the dose-volume histograms (DVHs) and on the normal tissue complication probabilities (NTCPs) of brain and eyes in dogs with nasal tumors. Nine dogs with large, caudally located nasal tumors were planned using conventional techniques and inverse planned IMRT for a total prescribed dose of 52.5 Gy in 3.5 Gy fractions. The equivalent uniform dose for brain and eyes was calculated to estimate the normal tissue complication probability (NTCP) of these organs. The NTCP values as well as the DVHs were used to compare the treatment plans. The dose distribution in IMRT plans was more conformal than in conventional plans. The average dose delivered to one-third of the brain was 10 Gy lower with the IMRT plan compared with conventional planning. The mean partial brain volume receiving 43.6 Gy or more was reduced by 25.6% with IMRT. As a consequence, the NTCPs were also significantly lower in the IMRT plans. The mean NTCP of brain was two times lower and at least one eye could be saved in all patients planed with IMRT. Another possibility with IMRT is dose escalation in the target to improve tumor control while keeping the NTCPs at the same level as for conventional planning. Veterinary

The cost of implementing inpatient bar code medication administration.

PubMed

Sakowski, Julie Ann; Ketchel, Alan

2013-02-01

To calculate the costs associated with implementing and operating an inpatient bar-code medication administration (BCMA) system in the community hospital setting and to estimate the cost per harmful error prevented. This is a retrospective, observational study. Costs were calculated from the hospital perspective and a cost-consequence analysis was performed to estimate the cost per preventable adverse drug event averted. Costs were collected from financial records and key informant interviews at 4 not-for profit community hospitals. Costs included direct expenditures on capital, infrastructure, additional personnel, and the opportunity costs of time for existing personnel working on the project. The number of adverse drug events prevented using BCMA was estimated by multiplying the number of doses administered using BCMA by the rate of harmful errors prevented by interventions in response to system warnings. Our previous work found that BCMA identified and intercepted medication errors in 1.1% of doses administered, 9% of which potentially could have resulted in lasting harm. The cost of implementing and operating BCMA including electronic pharmacy management and drug repackaging over 5 years is $40,000 (range: $35,600 to $54,600) per BCMA-enabled bed and $2000 (range: $1800 to $2600) per harmful error prevented. BCMA can be an effective and potentially cost-saving tool for preventing the harm and costs associated with medication errors.

Biokinetics and internal dosimetry of inhaled metal tritide particles

NASA Astrophysics Data System (ADS)

Wang, Yansheng

1998-12-01

Metal tritides (MT), stable chemical compounds of tritium, are widely used in nuclear engineering facilities. MT particles can be released as aerosols. Inhaling MT particles is a potential occupational radiation hazard. Little information is available on their dissolution behavior, biokinetics, and dosimetry. The objectives of present dissertation are to estimate dissolution rates, to develop biokinetic models, to improve internal dosimetric considerations, and to classify MT materials. This study consisted of three phases: In vitro dissolution in a simulated lung fluid, In vivo rat experiments on retention and clearance, and biokinetic modeling and dosimetric evaluation. There was a supporting study on self- absorption of tritium beta in MT particles. MT materials used in this study were titanium (Ti) and zirconium (Zr) tritides. Results shows considerable self-absorption of beta particles and their energy, even for respirable MT particles smaller than 5 μm. The self-absorption factors should be required for counting MT particle samples and for estimating absorbed dose to tissues. In vitro and in vivo dissolution data indicate that Ti and Zr tritides are poorly soluble materials. Ti tritide belongs to the W class or M type while Zr tritide can be classified as Y class or S type. Due to long retention time of the MT particles, tritium betas directly from the particles contribute over 90% of the absorbed dose to lung. The lung dose contributes most of the effective dose to the whole body. Dissolved tritium including tritiated water (HTO) and organically bound tritium (OBT) has less effect on the lung dose and effective dose. Results on the annual limit on intake (ALI) indicate that the current radiation protection guideline based on HTO is not adequate for inhalation exposure to MT particles and needs to be modified. The biokinetic models developed in this study have predictive powers to estimate the consequences of a human inhalation exposure to MT aerosols. The animal excretory patterns found from in vivo rat studies may provide useful information for nuclear engineering facilities to setup bioassay program in workplace. The applications of the results from this research are limited in their scopes.

Quantifying annual internal effective 137Cesium dose utilizing direct body-burden measurement and ecological dose modeling.

PubMed

Jelin, Benjamin A; Sun, Wenjie; Kravets, Alexandra; Naboka, Maryna; Stepanova, Eugenia I; Vdovenko, Vitaliy Y; Karmaus, Wilfried J; Lichosherstov, Alex; Svendsen, Erik R

2016-11-01

The Chernobyl Nuclear Power Plant (CNPP) accident represents one of the most significant civilian releases of 137 Cesium ( 137 Cs, radiocesium) in human history. In the Chernobyl-affected region, radiocesium is considered to be the greatest on-going environmental hazard to human health by radiobiologists and public health scientists. The goal of this study was to characterize dosimetric patterns and predictive factors for whole-body count (WBC)-derived radiocesium internal dose estimations in a CNPP-affected children's cohort, and cross-validate these estimations with a soil-based ecological dose estimation model. WBC data were used to estimate the internal effective dose using the International Commission on Radiological Protection (ICRP) 67 dose conversion coefficient for 137 Cs and MONDAL Version 3.01 software. Geometric mean dose estimates from each model were compared utilizing paired t-tests and intra-class correlation coefficients. Additionally, we developed predictive models for WBC-derived dose estimation in order to determine the appropriateness of EMARC to estimate dose for this population. The two WBC-derived dose predictive models identified 137 Cs soil concentration (P<0.0001) as the strongest predictor of annual internal effective dose from radiocesium validating the use of the soil-based EMARC model. The geometric mean internal effective dose estimate of the EMARC model (0.183 mSv/y) was the highest followed by the ICRP 67 dose estimates (0.165 mSv/y) and the MONDAL model estimates (0.149 mSv/y). All three models yielded significantly different geometric mean dose (P<0.05) estimates for this cohort when stratified by sex, age at time of exam and season of exam, except for the mean MONDAL and EMARC estimates for 15- and 16-year olds and mean ICRP and MONDAL estimates for children examined in Winter. Further prospective and retrospective radio-epidemiological studies utilizing refined WBC measurements and ecological model dose estimations, in conjunction with findings from animal toxicological studies, should help elucidate possible deterministic radiogenic health effects associated with chronic low-dose internal exposure to 137 Cs.

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 implies that the arithmetic mean of an uncertain estimate of the risk of a solid cancer per Gy at low acute doses or low dose rates of low linear energy transfer radiation is only about 10% less than the mean risk per Gy at higher acute doses. Data were also evaluated to define a low acute dose or low dose rate of low linear energy transfer radiation, i.e., a dose or dose rate below which a dose and dose-rate effectiveness factor should be applied in estimating risks of solid cancers.

A photon recycling approach to the denoising of ultra-low dose X-ray sequences.

PubMed

Hariharan, Sai Gokul; Strobel, Norbert; Kaethner, Christian; Kowarschik, Markus; Demirci, Stefanie; Albarqouni, Shadi; Fahrig, Rebecca; Navab, Nassir

2018-06-01

Clinical procedures that make use of fluoroscopy may expose patients as well as the clinical staff (throughout their career) to non-negligible doses of radiation. The potential consequences of such exposures fall under two categories, namely stochastic (mostly cancer) and deterministic risks (skin injury). According to the "as low as reasonably achievable" principle, the radiation dose can be lowered only if the necessary image quality can be maintained. Our work improves upon the existing patch-based denoising algorithms by utilizing a more sophisticated noise model to exploit non-local self-similarity better and this in turn improves the performance of low-rank approximation. The novelty of the proposed approach lies in its properly designed and parameterized noise model and the elimination of initial estimates. This reduces the computational cost significantly. The algorithm has been evaluated on 500 clinical images (7 patients, 20 sequences, 3 clinical sites), taken at ultra-low dose levels, i.e. 50% of the standard low dose level, during electrophysiology procedures. An average improvement in the contrast-to-noise ratio (CNR) by a factor of around 3.5 has been found. This is associated with an image quality achieved at around 12 (square of 3.5) times the ultra-low dose level. Qualitative evaluation by X-ray image quality experts suggests that the method produces denoised images that comply with the required image quality criteria. The results are consistent with the number of patches used, and they demonstrate that it is possible to use motion estimation techniques and "recycle" photons from previous frames to improve the image quality of the current frame. Our results are comparable in terms of CNR to Video Block Matching 3D-a state-of-the-art denoising method. But qualitative analysis by experts confirms that the denoised ultra-low dose X-ray images obtained using our method are more realistic with respect to appearance.

Estimation of occupational cosmic radiation exposure among airline personnel: Agreement between a job-exposure matrix, aggregate, and individual dose estimates.

PubMed

Talibov, Madar; Salmelin, Raili; Lehtinen-Jacks, Susanna; Auvinen, Anssi

2017-04-01

Job-exposure matrices (JEM) are used for exposure assessment in occupational studies, but they can involve errors. We assessed agreement between the Nordic Occupational Cancer Studies JEM (NOCCA-JEM) and aggregate and individual dose estimates for cosmic radiation exposure among Finnish airline personnel. Cumulative cosmic radiation exposure for 5,022 airline crew members was compared between a JEM and aggregate and individual dose estimates. The NOCCA-JEM underestimated individual doses. Intraclass correlation coefficient was 0.37, proportion of agreement 64%, kappa 0.46 compared with individual doses. Higher agreement was achieved with aggregate dose estimates, that is annual medians of individual doses and estimates adjusted for heliocentric potentials. The substantial disagreement between NOCCA-JEM and individual dose estimates of cosmic radiation may lead to exposure misclassification and biased risk estimates in epidemiological studies. Using aggregate data may provide improved estimates. Am. J. Ind. Med. 60:386-393, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A method for estimating dry forage intake by sheep using polyethylene glycol as a faecal marker measured with NIRS.

PubMed

Hassoun, P; Viudes, G; Autran, P; Bastianelli, D; Bocquier, F

2013-08-01

In experiments based on ruminants' individual dry matter intake (DMI) assessment, several external markers can be used to estimate faecal output when total faeces collection is not possible. However, preparation of the markers to be administered and analytical procedures used for marker content determination are time-consuming thus strongly limiting the number of animals involved in the experiments. In this paper, polyethylene glycol (PEG, molecular weight 6000 da) was tested as a faecal marker. Four trials were conducted on dry, non-lactating ewes kept in digestibility crates that allowed individual measurements. The overall experiment was designed to assess the major factors that could lessen the effectiveness of this method, assuming that the use of grab samples of faeces is sufficient. Trial 1 was designed to test two levels of PEG (20 and 40 g/day) administered in two equal amounts. Trial 2 was designed to test the effect of either a single morning (0800 h) dose (20 g/day) or a twice daily administration (0800 and 1600 h) of the same fractionated dose. Trial 3 was designed to test a 20 g/day dose of PEG administered once daily to ewes fed with hays of different qualities: medium (MH) and low (LH). In trial 4, a lower dose of PEG (10 g/day) was administered once a day to ewes fed with fresh oat-vetch forage. It was demonstrated that PEG could be precisely estimated (average prediction error = 3.47 g/kg) with near-infrared reflectance spectroscopy (NIRS). On the basis of the four trials, it has been proved that PEG administration (20 and 40 g/day) did not significantly affect the DMI of ewes fed dry diets (trials 1, 2 and 3), whereas there was an unexpected increase of DMI for ewes fed exclusively with green feed (trial 4) without DM digestibility modification. Providing PEG as a single dose (0800 h) or split into two equal parts (0800 and 1600 h) did not alter the estimated DMI. Considering the interest of grab sampling, there were clear variations of PEG in faeces with higher concentrations observed at 0800 and 1600 h and lower concentrations at 1400 h. Consequently, with PEG (measured with NIRS) administered once and using the grab sampling procedure (morning collection), it is possible to estimate the DMI of dry feeds with good accuracy. For green feeds, more research is needed as the estimated results are still highly variable.

Cancer risk estimation in Belarussian children due to thyroid irradiation as a consequence of the Chernobyl nuclear accident

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

Buglova, E.; Kenigsberg, J.E.; Sergeeva, N.V.

1996-07-01

The thyroid doses received by the juvenile population of Belarus following the Chernobyl accident ranged up to about 10 Gy. The thyroid cancer risk estimate recommended in NCRP Report No. 80 was used to predict the number of thyroid cancer cases among children during 1990-1992 in selected Belarussian regions and cities. The results obtained using this risk estimate show an excess of thyroid cancer cases being registered vs. the predicted cases. Thyroid cancer incidence rate among boys under investigation is higher than among girls in the postaccident period. The excess of the observed over the expected incidence in the generalmore » juvenile population is caused by the high thyroid cancer incidence rate among boys. These results, which can be considered part of the first stage of a thorough thyroid cancer risk estimation after the Chernobyl accident, demonstrate the critical need to complete these studies in depth. 6 refs., 5 figs., 3 tabs.« less

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.

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 (WED) and regional CTDI vol as variables and (b) using the same exponential relationship with the addition of categorical variables such as scanner model and organ to provide a more complete estimate of factors that may affect organ dose. Finally, estimates from generated models were compared to those obtained from SSDE and ImPACT. The Generalized Linear Model yielded organ dose estimates that were significantly closer to the MC reference organ dose values than were organ doses estimated via SSDE or ImPACT. Moreover, the GLM estimates were better than those of SSDE or ImPACT irrespective of whether or not categorical variables were used in the model. While the improvement associated with a categorical variable was substantial in estimating breast dose, the improvement was minor for other organs. The GLM approach extends the current CT dose estimation methods by allowing the use of additional variables to more accurately estimate organ dose from TCM scans. Thus, this approach may be able to overcome the limitations of current CT dose metrics to provide more accurate estimates of patient dose, in particular, dose to organs with considerable variability across the population. © 2017 American Association of Physicists in Medicine.

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

Economic evaluation of health consequences of prenatal methylmercury exposure in France.

PubMed

Pichery, Céline; Bellanger, Martine; Zmirou-Navier, Denis; Fréry, Nadine; Cordier, Sylvaine; Roue-Legall, Anne; Hartemann, Philippe; Grandjean, Philippe

2012-08-10

Evidence of a dose-response relationship between prenatal exposure to methylmercury (MeHg) and neurodevelopmental consequences in terms of IQ reduction, makes it possible to evaluate the economic consequences of MeHg exposures. To perform an economic evaluation of annual national benefits of reduction of the prenatal MeHg exposure in France. We used data on hair-Hg concentrations in French women of childbearing age (18-45 years) from a national sample of 126 women and from two studies conducted in coastal regions (n = 161and n = 503). A linear dose response function with a slope of 0.465 IQ point reduction per μg/g increase in hair-Hg concentration was used, along with a log transformation of the exposure scale, where a doubling of exposure was associated with a loss of 1.5 IQ points. The costs calculations utilized an updated estimate of €2008 17,363 per IQ point decrement, with three hypothetical exposure cut-off points (hair-Hg of 0.58, 1.0, and 2.5 μg/g). Because of higher exposure levels of women in coastal communities, the annual economic impacts based on these data were greater than those using the national data, i.e., € 1.62 billion (national), and € 3.02 billion and € 2.51 billion (regional), respectively, with the linear model, and € 5.46 billion (national), and € 9.13 billion and € 8.17 billion (regional), with the log model, for exposures above 0.58 μg/g. These results emphasize that efforts to reduce MeHg exposures would have high social benefits by preventing the serious and lifelong consequences of neurodevelopmental deficits in children.

SU-E-T-365: Estimation of Neutron Ambient Dose Equivalents for Radioprotection Exposed Workers in Radiotherapy Facilities Based On Characterization Patient Risk Estimation

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

Irazola, L; Terron, J; Sanchez-Doblado, F

2015-06-15

Purpose: Previous measurements with Bonner spheres{sup 1} showed that normalized neutron spectra are equal for the majority of the existing linacs{sup 2}. This information, in addition to thermal neutron fluences obtained in the characterization procedure{sup 3}3, would allow to estimate neutron doses accidentally received by exposed workers, without the need of an extra experimental measurement. Methods: Monte Carlo (MC) simulations demonstrated that the thermal neutron fluence distribution inside the bunker is quite uniform, as a consequence of multiple scatter in the walls{sup 4}. Although inverse square law is approximately valid for the fast component, a more precise calculation could bemore » obtained with a generic fast fluence distribution map around the linac, from MC simulations{sup 4}. Thus, measurements of thermal neutron fluences performed during the characterization procedure{sup 3}, together with a generic unitary spectra{sup 2}, would allow to estimate the total neutron fluences and H*(10) at any point{sup 5}. As an example, we compared estimations with Bonner sphere measurements{sup 1}, for two points in five facilities: 3 Siemens (15–23 MV), Elekta (15 MV) and Varian (15 MV). Results: Thermal neutron fluences obtained from characterization, are within (0.2–1.6×10{sup 6}) cm−{sup 2}•Gy{sup −1} for the five studied facilities. This implies ambient equivalent doses ranging from (0.27–2.01) mSv/Gy 50 cm far from the isocenter and (0.03–0.26) mSv/Gy at detector location with an average deviation of ±12.1% respect to Bonner measurements. Conclusion: The good results obtained demonstrate that neutron fluence and H*(10) can be estimated based on: (a) characterization procedure established for patient risk estimation in each facility, (b) generic unitary neutron spectrum and (c) generic MC map distribution of the fast component. [1] Radiat. Meas (2010) 45: 1391 – 1397; [2] Phys. Med. Biol (2012) 5 7:6167–6191; [3] Med. Phys (2015) 42:276 - 281. [4] IFMBE (2012) 39: 1245–1248. [5] ICRU Report 57 (1998)« less

A radiological assessment of nuclear power and propulsion operations near Space Station Freedom

NASA Technical Reports Server (NTRS)

Bolch, Wesley E.; Thomas, J. Kelly; Peddicord, K. Lee; Nelson, Paul; Marshall, David T.; Busche, Donna M.

1990-01-01

Scenarios were identified which involve the use of nuclear power systems in the vicinity of Space Station Freedom (SSF) and their radiological impact on the SSF crew was quantified. Several of the developed scenarios relate to the use of SSF as an evolutionary transportation node for lunar and Mars missions. In particular, radiation doses delivered to SSF crew were calculated for both the launch and subsequent return of a Nuclear Electric Propulsion (NEP) cargo vehicle and a Nuclear Thermal Rocket (NTR) personnel vehicle to low earth orbit. The use of nuclear power on co-orbiting platforms and the storage and handling issues associated with radioisotope power systems were also explored as they relate to SSF. A central philosophy in these analyses was the utilization of a radiation dose budget, defined as the difference between recommended dose limits from all radiation sources and estimated doses received by crew members from natural space radiations. Consequently, for each scenario examined, the dose budget concept was used to identify and quantify constraints on operational parameters such as launch separation distances, returned vehicle parking distances, and reactor shutdown times prior to vehicle approach. The results indicate that realistic scenarios do not exist which would preclude the use of nuclear power sources in the vicinity of SSF. The radiation dose to the SSF crew can be maintained at safe levels solely by implementing proper and reasonable operating procedures.

Emergency department management of patients internally contaminated with radioactive material

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

Kazzi, Ziad; Buzzell, Jennifer; Bertelli, Luiz

After a radiation emergency that involves the dispersal of radioactive material, patients can become externally and internally contaminated with one or more radionuclides. Internal contamination can lead to the delivery of harmful ionizing radiation doses to various organs and tissues or the whole body. The clinical consequences can range from acute radiation syndrome (ARS) to the long term development of cancer. Estimating the amount of radioactive material absorbed into the body can guide the management of patients. Treatment includes, in addition to supportive care and long term monitoring, certain medical countermeasures like Prussian blue, Calcium DTPA and Zinc DTPA.

Emergency department management of patients internally contaminated with radioactive material

DOE PAGES

Kazzi, Ziad; Buzzell, Jennifer; Bertelli, Luiz; ...

2014-11-15

After a radiation emergency that involves the dispersal of radioactive material, patients can become externally and internally contaminated with one or more radionuclides. Internal contamination can lead to the delivery of harmful ionizing radiation doses to various organs and tissues or the whole body. The clinical consequences can range from acute radiation syndrome (ARS) to the long term development of cancer. Estimating the amount of radioactive material absorbed into the body can guide the management of patients. Treatment includes, in addition to supportive care and long term monitoring, certain medical countermeasures like Prussian blue, Calcium DTPA and Zinc DTPA.

Emergency Department Management of Patients Internally Contaminated with Radioactive Material

PubMed Central

Kazzi, Ziad; Buzzell, Jennifer; Bertelli, Luiz; Christensen, Doran

2017-01-01

SUMMARY Internal contamination with radioactive material can expose patients to radiation leading to short- and long-term clinical consequences. After the patient’s emergency conditions are addressed and the skin is decontaminated, the treating physicians assess the amount of radioactive material that has been internalized. This evaluation allows the estimation of the radiation dose that is delivered the specific radionuclide inside the body and supports the need for additional therapies and monitoring. These complex assessments warrant the reliance on a multidisciplinary approach that incorporates local, regional, and national experts in radiation medicine and emergencies. PMID:25455668

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.

National Environmental Policy Act Hazards Assessment for the TREAT Alternative

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

Boyd D. Christensen; Annette L. Schafer

2013-11-01

This document provides an assessment of hazards as required by the National Environmental Policy Act for the alternative of restarting the reactor at the Transient Reactor Test (TREAT) facility by the Resumption of Transient Testing Program. Potential hazards have been identified and screening level calculations have been conducted to provide estimates of unmitigated dose consequences that could be incurred through this alternative. Consequences considered include those related to use of the TREAT Reactor, experiment assembly handling, and combined events involving both the reactor and experiments. In addition, potential safety structures, systems, and components for processes associated with operating TREAT andmore » onsite handling of nuclear fuels and experiments are listed. If this alternative is selected, a safety basis will be prepared in accordance with 10 CFR 830, “Nuclear Safety Management,” Subpart B, “Safety Basis Requirements.”« less

National Environmental Policy Act Hazards Assessment for the TREAT Alternative

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

Christensen, Boyd D.; Schafer, Annette L.

2014-02-01

This document provides an assessment of hazards as required by the National Environmental Policy Act for the alternative of restarting the reactor at the Transient Reactor Test (TREAT) facility by the Resumption of Transient Testing Program. Potential hazards have been identified and screening level calculations have been conducted to provide estimates of unmitigated dose consequences that could be incurred through this alternative. Consequences considered include those related to use of the TREAT Reactor, experiment assembly handling, and combined events involving both the reactor and experiments. In addition, potential safety structures, systems, and components for processes associated with operating TREAT andmore » onsite handling of nuclear fuels and experiments are listed. If this alternative is selected, a safety basis will be prepared in accordance with 10 CFR 830, “Nuclear Safety Management,” Subpart B, “Safety Basis Requirements.”« less

The 2015 global production capacity of seasonal and pandemic influenza vaccine.

PubMed

McLean, Kenneth A; Goldin, Shoshanna; Nannei, Claudia; Sparrow, Erin; Torelli, Guido

2016-10-26

A global shortage and inequitable access to influenza vaccines has been cause for concern for developing countries who face dire consequences in the event of a pandemic. The Global Action Plan for Influenza Vaccines (GAP) was launched in 2006 to increase global capacity for influenza vaccine production to address these concerns. It is widely recognized that well-developed infrastructure to produce seasonal influenza vaccines leads to increased capacity to produce pandemic influenza vaccines. This article summarizes the results of a survey administered to 44 manufacturers to assess their production capacity for seasonal influenza and pandemic influenza vaccine production. When the GAP was launched in 2006, global production capacity for seasonal and pandemic vaccines was estimated to be 500million and 1.5billion doses respectively. Since 2006 there has been a significant increase in capacity, with the 2013 survey estimating global capacity at 1.5billion seasonal and 6.2billion pandemic doses. Results of the current survey showed that global seasonal influenza vaccine production capacity has decreased since 2013 from 1.504billion doses to 1.467billion doses. However, notwithstanding the overall global decrease in seasonal vaccine capacity there were notable positive changes in the distribution of production capacity with increases noted in South East Asia (SEAR) and the Western Pacific (WPR) regions, albeit on a small scale. Despite a decrease in seasonal capacity, there has been a global increase of pandemic influenza vaccine production capacity from 6.2 billion doses in 2013 to 6.4 billion doses in 2015. This growth can be attributed to a shift towards more quadrivalent vaccine production and also to increased use of adjuvants. Pandemic influenza vaccine production capacity is at its highest recorded levels however challenges remain in maintaining this capacity and in ensuring access in the event of a pandemic to underserved regions. Copyright © 2016. Published by Elsevier Ltd.

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 work as it lays the foundation for the future of simulating TCM using Monte Carlo methods. As a result of this research organ dose can be estimated for individual patients undergoing specific conventional MDCT exams. This research also brings understanding to conventional and novel close reduction techniques in CT and their effect on organ dose.

Occupational exposures in two industrial plants devoted to the production of ammonium phosphate fertilisers.

PubMed

Bolívar, J P; García-Tenorio, R; Mosqueda, F; Gázquez, M J; López-Coto, I; Adame, J A; Vaca, F

2013-03-01

In order to fill a gap in the open literature, occupational exposures and activity concentrations have been assessed in two NORM industrial plants, located in the south-west of Spain, devoted to the production of mono-ammonium phosphate (MAP) and di-ammonium phosphate (DAP) fertilisers. The annual effective doses received by the workers from these plants are clearly below 1 mSv yr(-1) and the contribution due to external radiation is similar to that due to inhalation. The contribution to the maximum effective doses due to inhalation of particulate matter has been estimated to be about 0.12 mSv yr(-1), while the (222)Rn concentrations inside the plants are of no concern. Consequently, no additional actions or radiological protection measures need to be taken to decrease the natural radiation received by the workers in these facilities.

Determinants of Antibiotic Consumption - Development of a Model using Partial Least Squares Regression based on Data from India.

PubMed

Tamhankar, Ashok J; Karnik, Shreyasee S; Stålsby Lundborg, Cecilia

2018-04-23

Antibiotic resistance, a consequence of antibiotic use, is a threat to health, with severe consequences for resource constrained settings. If determinants for human antibiotic use in India, a lower middle income country, with one of the highest antibiotic consumption in the world could be understood, interventions could be developed, having implications for similar settings. Year wise data for India, for potential determinants and antibiotic consumption, was sourced from publicly available databases for the years 2000-2010. Data was analyzed using Partial Least Squares regression and correlation between determinants and antibiotic consumption was evaluated, formulating 'Predictors' and 'Prediction models'. The 'prediction model' with the statistically most significant predictors (root mean square errors of prediction for train set-377.0 and test set-297.0) formulated from a combination of Health infrastructure + Surface transport infrastructure (HISTI), predicted antibiotic consumption within 95% confidence interval and estimated an antibiotic consumption of 11.6 standard units/person (14.37 billion standard units totally; standard units = number of doses sold in the country; a dose being a pill, capsule, or ampoule) for India for 2014. The HISTI model may become useful in predicting antibiotic consumption for countries/regions having circumstances and data similar to India, but without resources to measure actual data of antibiotic consumption.

Food Stabilizing Antioxidants Increase Nutrient Bioavailability in the in Vitro Model.

PubMed

Mika, Magdalena; Wikiera, Agnieszka; Antończyk, Anna; Grabacka, Maja

2017-01-01

We investigated whether antioxidants may enhance bioavailability of lipids and carbohydrates and therefore increase the risk of obesity development. We tested how supplementation with antioxidants (0.01% butylated hydroxytoluene [BHT], α-tocopherol, and green tea catechins) of a diet containing butter and wheat bread affects bioavailability of fats and carbohydrates. The absorption of the in vitro digested diet was estimated in the intestinal epithelia model of the Caco-2 cells cultured in Transwell chambers. In the case of the antioxidant-supplemented diets, we observed increased bioavailability of glucose, cholesterol, and lipids, as well as elevated secretion of the main chylomicron protein apoB-48 to the basal compartment. Importantly, we did not detect any rise in the concentrations of lipid peroxidation products (malondialdehyde, MDA) in the control samples prepared without antioxidants. Addition of antioxidants (in particular BHT) to the diet increases bioavailability of lipids and carbohydrates, which consequently may increase the risk of obesity development. The dose of antioxidants is a factor of fundamental importance, particularly for catechins: low doses increase absorption of lipids, whereas high doses exert the opposite effect.

Whole-body to tissue concentration ratios for use in biota dose assessments for animals.

PubMed

Yankovich, Tamara L; Beresford, Nicholas A; Wood, Michael D; Aono, Tasuo; Andersson, Pål; Barnett, Catherine L; Bennett, Pamela; Brown, Justin E; Fesenko, Sergey; Fesenko, J; Hosseini, Ali; Howard, Brenda J; Johansen, Mathew P; Phaneuf, Marcel M; Tagami, Keiko; Takata, Hyoe; Twining, John R; Uchida, Shigeo

2010-11-01

Environmental monitoring programs often measure contaminant concentrations in animal tissues consumed by humans (e.g., muscle). By comparison, demonstration of the protection of biota from the potential effects of radionuclides involves a comparison of whole-body doses to radiological dose benchmarks. Consequently, methods for deriving whole-body concentration ratios based on tissue-specific data are required to make best use of the available information. This paper provides a series of look-up tables with whole-body:tissue-specific concentration ratios for non-human biota. Focus was placed on relatively broad animal categories (including molluscs, crustaceans, freshwater fishes, marine fishes, amphibians, reptiles, birds and mammals) and commonly measured tissues (specifically, bone, muscle, liver and kidney). Depending upon organism, whole-body to tissue concentration ratios were derived for between 12 and 47 elements. The whole-body to tissue concentration ratios can be used to estimate whole-body concentrations from tissue-specific measurements. However, we recommend that any given whole-body to tissue concentration ratio should not be used if the value falls between 0.75 and 1.5. Instead, a value of one should be assumed.

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 patient anatomy, a first order approximation of organ and effective doses from routine CT scan protocols can be reasonably estimated using size specific factors. Estimation accuracy is generally poor for organ outside the scan range and for neurological protocols. The dose calculator designed in this study can be used to conveniently estimate and report the dose values for a patient across a multiplicity of CT scan protocols.« less

Estimated rate of fatal automobile accidents attributable to acute solvent exposure at low inhaled concentrations.

PubMed

Benignus, Vernon A; Bushnell, Philip J; Boyes, William K

2011-12-01

Acute solvent exposures may contribute to automobile accidents because they increase reaction time and decrease attention, in addition to impairing other behaviors. These effects resemble those of ethanol consumption, both with respect to behavioral effects and neurological mechanisms. These observations, along with the extensive data on the relationship between ethanol consumption and fatal automobile accidents, suggested a way to estimate the probability of fatal automobile accidents from solvent inhalation. The problem can be approached using the logic of the algebraic transitive postulate of equality: if A=B and B=C, then A=C. We first calculated a function describing the internal doses of solvent vapors that cause the same magnitude of behavioral impairment as ingestion of ethanol (A=B). Next, we fit a function to data from the literature describing the probability of fatal car crashes for a given internal dose of ethanol (B=C). Finally, we used these two functions to generate a third function to estimate the probability of a fatal car crash for any internal dose of organic solvent vapor (A=C). This latter function showed quantitatively (1) that the likelihood of a fatal car crash is increased by acute exposure to organic solvent vapors at concentrations less than 1.0 ppm, and (2) that this likelihood is similar in magnitude to the probability of developing leukemia from exposure to benzene. This approach could also be applied to other potentially adverse consequences of acute exposure to solvents (e.g., nonfatal car crashes, property damage, and workplace accidents), if appropriate data were available. © 2011 Society for Risk Analysis Published 2011. This article is a U.S. Government work and is in the public domain for the U.S.A.

The interaction of natural background gamma radiation with depleted uranium micro-particles in the human body.

PubMed

Pattison, John E

2013-03-01

In this study, some characteristics of the photo-electrons produced when natural background gamma radiation interacts with micron-sized depleted uranium (DU) particles in the human body have been estimated using Monte Carlo simulations. In addition, an estimate has been made of the likelihood of radiological health effects occurring due to such an exposure. Upon exposure to naturally occurring background gamma radiation, DU particles in the body will produce an enhancement of the dose to the tissue in the immediate vicinity of the particles due to the photo-electric absorption of the radiation in the particle. In this study, the photo-electrons produced by a 10 μm-size particle embedded in tissue at the centre of the human torso have been investigated. The mean energies of the photo-electrons in the DU particle and in the two consecutive immediately surrounding 2 μm-wide tissue shells around the particle were found to be 38, 49 and 50 keV, respectively, with corresponding ranges of 1.3, 38 and 39 μm, respectively. The total photo-electron fluence-rates in the two consecutive 2 μm-wide tissue layers were found to be 14% and 7% of the fluence-rate in the DU particle, respectively. The estimated dose enhancement due to one 10 μm-sized DU particle in 1 cm(3) of tissue was less than 2 in 10 million of the dose received by the tissue without a particle being present. The increase in risk of death from cancer due to this effect is consequently insignificant.

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 discrepancy between the estimated organ dose and dose simulated using TCM Monte Carlo program was quantified. We further compared the convolution-based organ dose estimation method with two other strategies with different approaches of quantifying the irradiation field. The proposed convolution-based estimation method showed good accuracy with the organ dose simulated using the TCM Monte Carlo simulation. The average percentage error (normalized by CTDIvol) was generally within 10% across all organs and modulation profiles, except for organs located in the pelvic and shoulder regions. This study developed an improved method that accurately quantifies the irradiation field under TCM scans. The results suggested that organ dose could be estimated in real-time both prospectively (with the localizer information only) and retrospectively (with acquired CT data).

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

Health effects model for nuclear power plant accident consequence analysis. Part I. Introduction, integration, and summary. Part II. Scientific basis for health effects models

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

Evans, J.S.; Moeller, D.W.; Cooper, D.W.

1985-07-01

Analysis of the radiological health effects of nuclear power plant accidents requires models for predicting early health effects, cancers and benign thyroid nodules, and genetic effects. Since the publication of the Reactor Safety Study, additional information on radiological health effects has become available. This report summarizes the efforts of a program designed to provide revised health effects models for nuclear power plant accident consequence modeling. The new models for early effects address four causes of mortality and nine categories of morbidity. The models for early effects are based upon two parameter Weibull functions. They permit evaluation of the influence ofmore » dose protraction and address the issue of variation in radiosensitivity among the population. The piecewise-linear dose-response models used in the Reactor Safety Study to predict cancers and thyroid nodules have been replaced by linear and linear-quadratic models. The new models reflect the most recently reported results of the follow-up of the survivors of the bombings of Hiroshima and Nagasaki and permit analysis of both morbidity and mortality. The new models for genetic effects allow prediction of genetic risks in each of the first five generations after an accident and include information on the relative severity of various classes of genetic effects. The uncertainty in modeloling radiological health risks is addressed by providing central, upper, and lower estimates of risks. An approach is outlined for summarizing the health consequences of nuclear power plant accidents. 298 refs., 9 figs., 49 tabs.« less

The two-dimensional Monte Carlo: a new methodologic paradigm for dose reconstruction for epidemiological studies.

PubMed

Simon, Steven L; Hoffman, F Owen; Hofer, Eduard

2015-01-01

Retrospective dose estimation, particularly dose reconstruction that supports epidemiological investigations of health risk, relies on various strategies that include models of physical processes and exposure conditions with detail ranging from simple to complex. Quantification of dose uncertainty is an essential component of assessments for health risk studies since, as is well understood, it is impossible to retrospectively determine the true dose for each person. To address uncertainty in dose estimation, numerical simulation tools have become commonplace and there is now an increased understanding about the needs and what is required for models used to estimate cohort doses (in the absence of direct measurement) to evaluate dose response. It now appears that for dose-response algorithms to derive the best, unbiased estimate of health risk, we need to understand the type, magnitude and interrelationships of the uncertainties of model assumptions, parameters and input data used in the associated dose estimation models. Heretofore, uncertainty analysis of dose estimates did not always properly distinguish between categories of errors, e.g., uncertainty that is specific to each subject (i.e., unshared error), and uncertainty of doses from a lack of understanding and knowledge about parameter values that are shared to varying degrees by numbers of subsets of the cohort. While mathematical propagation of errors by Monte Carlo simulation methods has been used for years to estimate the uncertainty of an individual subject's dose, it was almost always conducted without consideration of dependencies between subjects. In retrospect, these types of simple analyses are not suitable for studies with complex dose models, particularly when important input data are missing or otherwise not available. The dose estimation strategy presented here is a simulation method that corrects the previous deficiencies of analytical or simple Monte Carlo error propagation methods and is termed, due to its capability to maintain separation between shared and unshared errors, the two-dimensional Monte Carlo (2DMC) procedure. Simply put, the 2DMC method simulates alternative, possibly true, sets (or vectors) of doses for an entire cohort rather than a single set that emerges when each individual's dose is estimated independently from other subjects. Moreover, estimated doses within each simulated vector maintain proper inter-relationships such that the estimated doses for members of a cohort subgroup that share common lifestyle attributes and sources of uncertainty are properly correlated. The 2DMC procedure simulates inter-individual variability of possibly true doses within each dose vector and captures the influence of uncertainty in the values of dosimetric parameters across multiple realizations of possibly true vectors of cohort doses. The primary characteristic of the 2DMC approach, as well as its strength, are defined by the proper separation between uncertainties shared by members of the entire cohort or members of defined cohort subsets, and uncertainties that are individual-specific and therefore unshared.

Dose-rate effect of ultrashort electron beam radiation on DNA damage and repair in vitro.

PubMed

Babayan, Nelly; Hovhannisyan, Galina; Grigoryan, Bagrat; Grigoryan, Ruzanna; Sarkisyan, Natalia; Tsakanova, Gohar; Haroutiunian, Samvel; Aroutiounian, Rouben

2017-11-01

Laser-generated electron beams are distinguished from conventional accelerated particles by ultrashort beam pulses in the femtoseconds to picoseconds duration range, and their application may elucidate primary radiobiological effects. The aim of the present study was to determine the dose-rate effect of laser-generated ultrashort pulses of 4 MeV electron beam radiation on DNA damage and repair in human cells. The dose rate was increased via changing the pulse repetition frequency, without increasing the electron energy. The human chronic myeloid leukemia K-562 cell line was used to estimate the DNA damage and repair after irradiation, via the comet assay. A distribution analysis of the DNA damage was performed. The same mean level of initial DNA damages was observed at low (3.6 Gy/min) and high (36 Gy/min) dose-rate irradiation. In the case of low-dose-rate irradiation, the detected DNA damages were completely repairable, whereas the high-dose-rate irradiation demonstrated a lower level of reparability. The distribution analysis of initial DNA damages after high-dose-rate irradiation revealed a shift towards higher amounts of damage and a broadening in distribution. Thus, increasing the dose rate via changing the pulse frequency of ultrafast electrons leads to an increase in the complexity of DNA damages, with a consequent decrease in their reparability. Since the application of an ultrashort pulsed electron beam permits us to describe the primary radiobiological effects, it can be assumed that the observed dose-rate effect on DNA damage/repair is mainly caused by primary lesions appearing at the moment of irradiation. © The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

Dynamics of Cellular Responses to Radiation

PubMed Central

Wodarz, Dominik; Sorace, Ron; Komarova, Natalia L.

2014-01-01

Understanding the consequences of exposure to low dose ionizing radiation is an important public health concern. While the risk of low dose radiation has been estimated by extrapolation from data at higher doses according to the linear non-threshold model, it has become clear that cellular responses can be very different at low compared to high radiation doses. Important phenomena in this respect include radioadaptive responses as well as low-dose hyper-radiosensitivity (HRS) and increased radioresistance (IRR). With radioadaptive responses, low dose exposure can protect against subsequent challenges, and two mechanisms have been suggested: an intracellular mechanism, inducing cellular changes as a result of the priming radiation, and induction of a protected state by inter-cellular communication. We use mathematical models to examine the effect of these mechanisms on cellular responses to low dose radiation. We find that the intracellular mechanism can account for the occurrence of radioadaptive responses. Interestingly, the same mechanism can also explain the existence of the HRS and IRR phenomena, and successfully describe experimentally observed dose-response relationships for a variety of cell types. This indicates that different, seemingly unrelated, low dose phenomena might be connected and driven by common core processes. With respect to the inter-cellular communication mechanism, we find that it can also account for the occurrence of radioadaptive responses, indicating redundancy in this respect. The model, however, also suggests that the communication mechanism can be vital for the long term survival of cell populations that are continuously exposed to relatively low levels of radiation, which cannot be achieved with the intracellular mechanism in our model. Experimental tests to address our model predictions are proposed. PMID:24722167

Final safety analysis report for the Galileo mission: Volume 3 (Book 2), Nuclear risk analysis document: Appendices: Revision 1

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

Not Available

1989-01-25

It is the purpose of the NRAD to provide an analysis of the range of potential consequences of accidents which have been identified that are associated with the launching and deployment of the Galileo mission spacecraft. The specific consequences analyzed are those associated with the possible release of radioactive material (fuel) of the Radioisotope Thermoelectric Generators (RTGs). They are in terms of radiation doses to people and areas of deposition of radioactive material. These consequence analyses can be used in several ways. One way is to identify the potential range of consequences which might have to be dealt with ifmore » there were to be an accident with a release of fuel, so as to assure that, given such an accident, the health and safety of the public will be reasonably protected. Another use of the information, in conjunction with accident and release probabilities, is to estimate the risks associated with the mission. That is, most space launches occur without incident. Given an accident, the most probable result relative to the RTGs is complete containment of the radioactive material. Only a small fraction of accidents might result in a release of fuel and subsequent radiological consequences. The combination of probability with consequence is risk, which can be compared to other human and societal risks to assure that no undue risks are implied by undertaking the mission. Book 2 contains eight appendices.« less

Safety analysis report for the Galileo Mission. Volume 3, book 2: Nuclear risk analysis document. Appendices, revision 1

NASA Astrophysics Data System (ADS)

1989-01-01

It is the purpose of the NRAD to provide an analysis of the range of potential consequences of accidents which have been identified that are associated with the launching and deployment of the Galileo mission spacecraft. The specific consequences analyzed are those associated with the possible release of radioactive material (fuel) of the Radioisotope Thermoelectric Generators (RTGs). They are in terms of radiation doses to people and areas of deposition of radioactive material. These consequence analyses can be used in several ways. One way is to identify the potential range of consequences which might have to be dealt with if there were to be an accident with a release of fuel, so as to assure that, given such an accident, the health and safety of the public will be reasonably protected. Another use of the information, in conjunction with accident and release probabilities, is to estimate the risks associated with the mission. That is, most space launches occur without incident. Given an accident, the most probable result relative to the RTGs is complete containment of the radioactive material. Only a small fraction of accidents might result in a release of fuel and subsequent radiological consequences. The combination of probability with consequence is risk, which can be compared to other human and societal risks to assure that no undue risks are implied by undertaking the mission. Book 2 contains eight appendices.

Spatial distribution of uranium and basic water quality parameter in the capital of Bihar and consequent ingestion dose.

PubMed

Kumar, Deepak; Singh, Anshuman; Jha, Rishi Kumar

2018-04-21

Investigation of presence of Uranium (U) in groundwater/drinking water is an active are of research due to its chemical and radiological toxicity as well as long-term health effects. The current study had the objective of estimating U as a naturally occurring radioactive element in groundwater samples and assessment of ingestion dose, when groundwater is the source of drinking water. The random sampling method was chosen for the collection of samples based on population density. The estimation of U was done using LED fluorimeter. Statistical tools were applied to analyze the data and its spatial distribution. The U concentrations in three blocks of urban Patna were well below the permissible limits suggested by different health agencies of the world. A correlation test was performed to analyze the association of U with other physiochemical parameters of water samples. It was found that the sulfate, chloride, calcium, hardness, alkalinity, TDS, salinity, and ORP were positively correlated, whereas fluoride, phosphate, magnesium, dissolved oxygen, and pH were negatively correlated with U concentrations. The ingestion dose due to U, occurring in groundwater, was found to vary from 0.2-27.0 μSv y -1 with a mean of 4.2 μSv y - 1 , which was well below the recommended limit of 0.1 mSv (WHO WHO Chron 38:104-108, 2012).Therefore, the water in this region is fit for drinking purposes.

Radiation sterilization of skin allograft

NASA Astrophysics Data System (ADS)

Kairiyama, E.; Horak, C.; Spinosa, M.; Pachado, J.; Schwint, O.

2009-07-01

In the treatment of burns or accidental loss of skin, cadaveric skin allografts provide an alternative to temporarily cover a wounded area. The skin bank facility is indispensable for burn care. The first human skin bank was established in Argentina in 1989; later, 3 more banks were established. A careful donor selection is carried out according to the national regulation in order to prevent transmissible diseases. As cadaveric human skin is naturally highly contaminated, a final sterilization is necessary to reach a sterility assurance level (SAL) of 10 -6. The sterilization dose for 106 batches of processed human skin was determined on the basis of the Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control (2004) and ISO 11137-2 (2006). They ranged from 17.6 to 33.4 kGy for bioburdens of >10-162.700 CFU/100 cm 2. The presence of Gram negative bacteria was checked for each produced batch. From the analysis of the experimental results, it was observed that the bioburden range was very wide and consequently the estimated sterilization doses too. If this is the case, the determination of a tissue-specific dose per production batch is necessary to achieve a specified requirement of SAL. Otherwise if the dose of 25 kGy is preselected, a standardized method for substantiation of this dose should be done to confirm the radiation sterilization process.

Costs of diarrheal disease and the cost-effectiveness of a rotavirus vaccination program in kyrgyzstan.

PubMed

Flem, Elmira T; Latipov, Renat; Nurmatov, Zuridin S; Xue, Yiting; Kasymbekova, Kaliya T; Rheingans, Richard D

2009-11-01

We examined the cost-effectiveness of a rotavirus immunization program in Kyrgyzstan, a country eligible for vaccine funding from the GAVI Alliance. We estimated the burden of rotavirus disease and its economic consequences by using national and international data. A cost-effectiveness analysis was conducted from government and societal perspectives, along with a range of 1-way sensitivity analyses. Rotavirus-related hospitalizations and outpatient visits cost US$580,864 annually, of which $421,658 (73%) is direct medical costs and $159,206 (27%) is nonmedical and indirect costs. With 95% coverage, vaccination could prevent 75% of rotavirus-related hospitalizations and deaths and 56% of outpatient visits and could avert $386,193 (66%) in total costs annually. The medical break-even price at which averted direct medical costs equal vaccination costs is $0.65/dose; the societal break-even price is $1.14/dose for a 2-dose regimen. At the current GAVI Alliance-subsidized vaccine price of $0.60/course, rotavirus vaccination is cost-saving for the government. Vaccination is cost-effective at a vaccine price $9.41/dose, according to the cost-effectiveness standard set by the 2002 World Health Report. Addition of rotavirus vaccines to childhood immunization in Kyrgyzstan could substantially reduce disease burden and associated costs. Vaccination would be cost-effective from the national perspective at a vaccine price $9.41 per dose.

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.

Lifetimes and spatio-temporal response of protein crystals in intense X-ray microbeams

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

Warkentin, Matthew A.; Atakisi, Hakan; Hopkins, Jesse B.

Serial synchrotron-based crystallography using intense microfocused X-ray beams, fast-framing detectors and protein microcrystals held at 300 K promises to expand the range of accessible structural targets and to increase overall structure-pipeline throughputs. To explore the nature and consequences of X-ray radiation damage under microbeam illumination, the time-, dose- and temperature-dependent evolution of crystal diffraction have been measured with maximum dose rates of 50 MGy s −1 . At all temperatures and dose rates, the integrated diffraction intensity for a fixed crystal orientation shows non-exponential decays with dose. Non-exponential decays are a consequence of non-uniform illumination and the resulting spatial evolution of diffracted intensitymore » within the illuminated crystal volume. To quantify radiation-damage lifetimes and the damage state of diffracting crystal regions, a revised diffraction-weighted dose (DWD) is defined and it is shown that for Gaussian beams the DWD becomes nearly independent of actual dose at large doses. An apparent delayed onset of radiation damage seen in some intensity–dose curves is in fact a consequence of damage. Intensity fluctuations at high dose rates may arise from the impulsive release of gaseous damage products. Accounting for these effects, data collection at the highest dose rates increases crystal radiation lifetimes near 300 K (but not at 100 K) by a factor of ∼1.5–2 compared with those observed at conventional dose rates. Improved quantification and modeling of the complex spatio-temporal evolution of protein microcrystal diffraction in intense microbeams will enable more efficient data collection, and will be essential in improving the accuracy of structure factors and structural models.« less

Lifetimes and spatio-temporal response of protein crystals in intense X-ray microbeams

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

Warkentin, Matthew A.; Atakisi, Hakan; Hopkins, Jesse B.

Serial synchrotron-based crystallography using intense microfocused X-ray beams, fast-framing detectors and protein microcrystals held at 300 K promises to expand the range of accessible structural targets and to increase overall structure-pipeline throughputs. To explore the nature and consequences of X-ray radiation damage under microbeam illumination, the time-, dose- and temperature-dependent evolution of crystal diffraction have been measured with maximum dose rates of 50 MGy s –1. At all temperatures and dose rates, the integrated diffraction intensity for a fixed crystal orientation shows non-exponential decays with dose. Non-exponential decays are a consequence of non-uniform illumination and the resulting spatial evolution ofmore » diffracted intensity within the illuminated crystal volume. To quantify radiation-damage lifetimes and the damage state of diffracting crystal regions, a revised diffraction-weighted dose (DWD) is defined and it is shown that for Gaussian beams the DWD becomes nearly independent of actual dose at large doses. An apparent delayed onset of radiation damage seen in some intensity–dose curves is in fact a consequence of damage. Intensity fluctuations at high dose rates may arise from the impulsive release of gaseous damage products. Accounting for these effects, data collection at the highest dose rates increases crystal radiation lifetimes near 300 K (but not at 100 K) by a factor of ~1.5–2 compared with those observed at conventional dose rates. As a result, improved quantification and modeling of the complex spatio-temporal evolution of protein microcrystal diffraction in intense microbeams will enable more efficient data collection, and will be essential in improving the accuracy of structure factors and structural models.« less

Lifetimes and spatio-temporal response of protein crystals in intense X-ray microbeams

DOE PAGES

Warkentin, Matthew A.; Atakisi, Hakan; Hopkins, Jesse B.; ...

2017-10-13

Serial synchrotron-based crystallography using intense microfocused X-ray beams, fast-framing detectors and protein microcrystals held at 300 K promises to expand the range of accessible structural targets and to increase overall structure-pipeline throughputs. To explore the nature and consequences of X-ray radiation damage under microbeam illumination, the time-, dose- and temperature-dependent evolution of crystal diffraction have been measured with maximum dose rates of 50 MGy s –1. At all temperatures and dose rates, the integrated diffraction intensity for a fixed crystal orientation shows non-exponential decays with dose. Non-exponential decays are a consequence of non-uniform illumination and the resulting spatial evolution ofmore » diffracted intensity within the illuminated crystal volume. To quantify radiation-damage lifetimes and the damage state of diffracting crystal regions, a revised diffraction-weighted dose (DWD) is defined and it is shown that for Gaussian beams the DWD becomes nearly independent of actual dose at large doses. An apparent delayed onset of radiation damage seen in some intensity–dose curves is in fact a consequence of damage. Intensity fluctuations at high dose rates may arise from the impulsive release of gaseous damage products. Accounting for these effects, data collection at the highest dose rates increases crystal radiation lifetimes near 300 K (but not at 100 K) by a factor of ~1.5–2 compared with those observed at conventional dose rates. As a result, improved quantification and modeling of the complex spatio-temporal evolution of protein microcrystal diffraction in intense microbeams will enable more efficient data collection, and will be essential in improving the accuracy of structure factors and structural models.« less

Lifetimes and spatio-temporal response of protein crystals in intense X-ray microbeams

DOE PAGES

Warkentin, Matthew A.; Atakisi, Hakan; Hopkins, Jesse B.; ...

2017-10-13

Serial synchrotron-based crystallography using intense microfocused X-ray beams, fast-framing detectors and protein microcrystals held at 300 K promises to expand the range of accessible structural targets and to increase overall structure-pipeline throughputs. To explore the nature and consequences of X-ray radiation damage under microbeam illumination, the time-, dose- and temperature-dependent evolution of crystal diffraction have been measured with maximum dose rates of 50 MGy s −1 . At all temperatures and dose rates, the integrated diffraction intensity for a fixed crystal orientation shows non-exponential decays with dose. Non-exponential decays are a consequence of non-uniform illumination and the resulting spatial evolution of diffracted intensitymore » within the illuminated crystal volume. To quantify radiation-damage lifetimes and the damage state of diffracting crystal regions, a revised diffraction-weighted dose (DWD) is defined and it is shown that for Gaussian beams the DWD becomes nearly independent of actual dose at large doses. An apparent delayed onset of radiation damage seen in some intensity–dose curves is in fact a consequence of damage. Intensity fluctuations at high dose rates may arise from the impulsive release of gaseous damage products. Accounting for these effects, data collection at the highest dose rates increases crystal radiation lifetimes near 300 K (but not at 100 K) by a factor of ∼1.5–2 compared with those observed at conventional dose rates. Improved quantification and modeling of the complex spatio-temporal evolution of protein microcrystal diffraction in intense microbeams will enable more efficient data collection, and will be essential in improving the accuracy of structure factors and structural models.« less

Cytogenetic Reconstruction of Gamma-Ray Doses Delivered to Atomic Bomb Survivors: Dealing with Wide Distributions of Photon Energies and Contributions from Hematopoietic Stem/Progenitor Cells.

PubMed

Nakamura, Nori; Hirai, Yuko; Kodama, Yoshiaki; Hamasaki, Kanya; Cullings, Harry M; Cordova, Kismet A; Awa, Akio

2017-10-01

Retrospective estimation of the doses received by atomic bomb (A-bomb) survivors by cytogenetic methods has been hindered by two factors: One is that the photon energies released from the bomb were widely distributed, and since the aberration yield varies depending on the energy, the use of monoenergetic 60 Co gamma radiation to construct a calibration curve may bias the estimate. The second problem is the increasing proportion of newly formed lymphocytes entering into the lymphocyte pool with increasing time intervals since the exposures. These new cells are derived from irradiated precursor/stem cells whose radiosensitivity may differ from that of blood lymphocytes. To overcome these problems, radiation doses to tooth enamel were estimated using the electron spin resonance (ESR; or EPR, electron paramagnetic resonance) method and compared with the cytogenetically estimated doses from the same survivors. The ESR method is only weakly dependent on the photon energy and independent of the years elapsed since an exposure. Both ESR and cytogenetic doses were estimated from 107 survivors. The latter estimates were made by assuming that although a part of the cells examined could be lymphoid stem or precursor cells at the time of exposure, all the cells had the same radiosensitivity as blood lymphocytes, and that the A-bomb gamma-ray spectrum was the same as that of the 60 Co gamma rays. Subsequently, ESR and cytogenetic endpoints were used to estimate the kerma doses using individual DS02R1 information on shielding conditions. The results showed that the two sets of kerma doses were in close agreement, indicating that perhaps no correction is needed in estimating atomic bomb gamma-ray doses from the cytogenetically estimated 60 Co gamma-ray equivalent doses. The present results will make it possible to directly compare cytogenetic doses with the physically estimated doses of the survivors, which would pave the way for testing whether or not there are any systematic trends or factors affecting physically estimated doses.

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

CANCER RISKS ATTRIBUTABLE TO LOW DOSES OF IONIZING RADIATION - ASSESSING WHAT WE REALLY KNOW?

EPA Science Inventory

Cancer Risks Attributable to Low Doses of Ionizing Radiation - What Do We Really Know?

Abstract
High doses of ionizing radiation clearly produce deleterious consequences in humans including, but not exclusively, cancer induction. At very low radiation doses the situatio...

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.

An assessment of the doses received by members of the public in Japan following the nuclear accident at Fukushima Daiichi nuclear power plant.

PubMed

Bedwell, P; Mortimer, K; Wellings, J; Sherwood, J; Leadbetter, S J; Haywood, S M; Charnock, T; Jones, A R; Hort, M C

2015-12-01

The earthquake and tsunami on 11 March 2011, centred off the east coast of Japan, caused considerable destruction and substantial loss of life along large swathes of the Japanese coastline. The tsunami damaged the Fukushima Daiichi nuclear power plant (NPP), resulting in prolonged releases of radioactive material into the environment. This paper assesses the doses received by members of the public in Japan. The assessment is based on an estimated source term and atmospheric dispersion modelling rather than monitoring data. It is evident from this assessment that across the majority of Japan the estimates of dose are very low, for example they are estimated to be less than the annual average dose from natural background radiation in Japan. Even in the regions local to Fukushima Daiichi NPP (and not affected by any form of evacuation) the maximum lifetime effective dose is estimated to be well below the cumulative natural background dose over the same period. The impact of the urgent countermeasures on the estimates of dose was considered. And the relative contribution to dose from the range of exposure pathways and radionuclides were evaluated. Analysis of estimated doses focused on the geographic irregularity and the impact of the meteorological conditions. For example the dose to an infant's thyroid received over the first year was estimated to be greater in Hirono than in the non-evacuated region of Naraha, despite Hirono being further from the release location. A number of factors were identified and thought to contribute towards this outcome, including the local wind pattern which resulted in the recirculation of part of the release. The non-uniform nature of dose estimates strengthens the case for evaluations based on dispersion modelling.

Comparing risk estimates following diagnostic CT radiation exposures employing different methodological approaches.

PubMed

Kashcheev, Valery V; Pryakhin, Evgeny A; Menyaylo, Alexander N; Chekin, Sergey Yu; Ivanov, Viktor K

2014-06-01

The current study has two aims: the first is to quantify the difference between radiation risks estimated with the use of organ or effective doses, particularly when planning pediatric and adult computed tomography (CT) examinations. The second aim is to determine the method of calculating organ doses and cancer risk using dose-length product (DLP) for typical routine CT examinations. In both cases, the radiation-induced cancer risks from medical CT examinations were evaluated as a function of gender and age. Lifetime attributable risk values from CT scanning were estimated with the use of ICRP (Publication 103) risk models and Russian national medical statistics data. For populations under the age of 50 y, the risk estimates based on organ doses usually are 30% higher than estimates based on effective doses. In older populations, the difference can be up to a factor of 2.5. The typical distributions of organ doses were defined for Chest Routine, Abdominal Routine, and Head Routine examinations. The distributions of organ doses were dependent on the anatomical region of scanning. The most exposed organs/tissues were thyroid, breast, esophagus, and lungs in cases of Chest Routine examination; liver, stomach, colon, ovaries, and bladder in cases of Abdominal Routine examination; and brain for Head Routine examinations. The conversion factors for calculation of typical organ doses or tissues at risk using DLP were determined. Lifetime attributable risk of cancer estimated with organ doses calculated from DLP was compared with the risk estimated on the basis of organ doses measured with the use of silicon photodiode dosimeters. The estimated difference in LAR is less than 29%.

Estimation of Potential Population Level Effects of Contaminants on Wildlife

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

Loar, J.M.

2001-06-11

The objective of this project is to provide DOE with improved methods to assess risks from contaminants to wildlife populations. The current approach for wildlife risk assessment consists of comparison of contaminant exposure estimates for individual animals to literature-derived toxicity test endpoints. These test endpoints are assumed to estimate thresholds for population-level effects. Moreover, species sensitivities to contaminants is one of several criteria to be considered when selecting assessment endpoints (EPA 1997 and 1998), yet data on the sensitivities of many birds and mammals are lacking. The uncertainties associated with this approach are considerable. First, because toxicity data are notmore » available for most potential wildlife endpoint species, extrapolation of toxicity data from test species to the species of interest is required. There is no consensus on the most appropriate extrapolation method. Second, toxicity data are represented as statistical measures (e.g., NOAEL s or LOAELs) that provide no information on the nature or magnitude of effects. The level of effect is an artifact of the replication and dosing regime employed, and does not indicate how effects might increase with increasing exposure. Consequently, slight exceedance of a LOAEL is not distinguished from greatly exceeding it. Third, the relationship of toxic effects on individuals to effects on populations is poorly estimated by existing methods. It is assumed that if the exposure of individuals exceeds levels associated with impaired reproduction, then population level effects are likely. Uncertainty associated with this assumption is large because depending on the reproductive strategy of a given species, comparable levels of reproductive impairment may result in dramatically different population-level responses. This project included several tasks to address these problems: (1) investigation of the validity of the current allometric scaling approach for interspecies extrapolation an d development of new scaling models; (2) development of dose-response models for toxicity data presented in the literature; and (3) development of matrix-based population models that were coupled with dose-response models to provide realistic estimation of population-level effects for individual responses.« less

Properties of model-averaged BMDLs: a study of model averaging in dichotomous response risk estimation.

PubMed

Wheeler, Matthew W; Bailer, A John

2007-06-01

Model averaging (MA) has been proposed as a method of accounting for model uncertainty in benchmark dose (BMD) estimation. The technique has been used to average BMD dose estimates derived from dichotomous dose-response experiments, microbial dose-response experiments, as well as observational epidemiological studies. While MA is a promising tool for the risk assessor, a previous study suggested that the simple strategy of averaging individual models' BMD lower limits did not yield interval estimators that met nominal coverage levels in certain situations, and this performance was very sensitive to the underlying model space chosen. We present a different, more computationally intensive, approach in which the BMD is estimated using the average dose-response model and the corresponding benchmark dose lower bound (BMDL) is computed by bootstrapping. This method is illustrated with TiO(2) dose-response rat lung cancer data, and then systematically studied through an extensive Monte Carlo simulation. The results of this study suggest that the MA-BMD, estimated using this technique, performs better, in terms of bias and coverage, than the previous MA methodology. Further, the MA-BMDL achieves nominal coverage in most cases, and is superior to picking the "best fitting model" when estimating the benchmark dose. Although these results show utility of MA for benchmark dose risk estimation, they continue to highlight the importance of choosing an adequate model space as well as proper model fit diagnostics.

Dose-response relationships and extrapolation in toxicology - Mechanistic and statistical considerations

EPA Science Inventory

Controversy on toxicological dose-response relationships and low-dose extrapolation of respective risks is often the consequence of misleading data presentation, lack of differentiation between types of response variables, and diverging mechanistic interpretation. In this chapter...

Single-hit mechanism of tumour cell killing by radiation.

PubMed

Chapman, J D

2003-02-01

To review the relative importance of the single-hit mechanism of radiation killing for tumour response to 1.8-2.0 Gy day(-1) fractions and to low dose-rate brachytherapy. Tumour cell killing by ionizing radiation is well described by the linear-quadratic equation that contains two independent components distinguished by dose kinetics. Analyses of tumour cell survival curves that contain six or more dose points usually provide good estimates of the alpha- and beta-inactivation coefficients. Superior estimates of tumour cell intrinsic radiosensitivity are obtained when synchronized populations are employed. The characteristics of single-hit inactivation of tumour cells are reviewed and compared with the characteristics of beta-inactivation. Potential molecular targets associated with single-hit inactivation are discussed along with strategies for potentiating cell killing by this mechanism. The single-hit mechanism of tumour cell killing shows no dependence on dose-rate and, consequently, no evidence of sublethal damage repair. It is uniquely potentiated by high linear-energy-transfer radiation, exhibits a smaller oxygen enhancement ratio and exhibits a larger indirect effect by hydroxyl radicals than the beta-mechanism. alpha-inactivation coefficients vary slightly throughout interphase but mitotic cells exhibit extremely high alpha-coefficients in the range of those observed for lymphocytes and some repair-deficient cells. Evidence is accumulating to suggest that chromatin in compacted form could be a radiation-hypersensitive target associated with single-hit radiation killing. Analyses of tumour cell survival curves demonstrate that it is the single-hit mechanism (alpha) that determines the majority of cell killing after doses of 2Gy and that this mechanism is highly variable between tumour cell lines. The characteristics of single-hit inactivation are qualitatively and quantitatively distinct from those of beta-inactivation. Compacted chromatin in tumour cells should be further investigated as a radiation-hypersensitive target that could be modulated for therapeutic advantage.

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.

Normalized dose data for upper gastrointestinal tract contrast studies performed to infants

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

Damilakis, John; Stratakis, John; Raissaki, Maria

The aim of the current study was to (a) provide normalized dose data for the estimation of the radiation dose from upper gastrointestinal tract contrast (UGIC) studies carried out to infants and (b) estimate the average patient dose and risks associated with radiation from UGIC examinations performed in our institution. Organ and effective doses, normalized to entrance skin dose (ESD) and dose area product (DAP) were estimated for UGIC procedures utilizing the Monte Carlo N-particle (MCNP) transport code and two mathematical phantoms, one corresponding to the size of a newborn and one to the size of a 1-year-old child. Themore » validity of the MCNP results was verified by comparison with dose data obtained in physical anthropomorphic phantoms simulating a newborn and a 1-year-old infant using thermoluminescence dosimetry (TLD). Data were also collected from 25 consecutive UGIC examinations performed to infants. Study participants were (a) 12 infants aged from 0.5 to 5.9 months (group 1) and (b) 13 infants aged from 6 to 15 months (group 2). For each examination, ESD and dose to comforters were measured using TLD. Patient effective doses were estimated using normalized dose data obtained in the simulation study. The risk for fatal cancer induction was estimated using appropriate coefficients. The results consist of tabulated dose data normalized to ESD or DAP for the estimation of patient dose. Conversion coefficients were estimated for various tube potentials and beam filtration values. The mean total fluoroscopy time was 1.26 and 1.62 min for groups 1 and 2, respectively. The average effective dose was 1.6 mSv for group 1 and 1.9 mSv for group 2. The risk of cancer attributable to the radiation exposure associated with a typical UGIC study was found to be up to 3 per 10 000 infants undergoing an UGIC examination. The mean radiation dose absorbed by the hands of comforters was 47 {mu}Gy. In conclusion, estimation of radiation doses associated with UGIC studies performed to infants can be made using the normalized dose data provided in the current study. Radiation dose values associated with UGIC examinations carried out to infants are not low and should be minimized as much as possible.« less

Patient doses in the healing arts

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

NONE

Determinations of radiation doses to patients from x-ray procedures and radiopharmaceuticals are detailed in this chapter. Instructions are given for estimating doses from x-ray procedures. For selected pediatric procedures, the methodology developed by the Food and Drug Administration is presented. The effect of testicular and ovarian shielding is illustrated in tabular form. Estimates of the Genetically Significant Dose (GSD) and mean annual bone marrow dose from diagnostic x-ray examinations are presented for the US populations (1990). This chapter also provides tables of patient doses from selected nuclear medicine procedures and estimates of fetal doses from {sup 131}I.

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

Simon, S.L.; Kerber, R.L.; Stevens, W.

This paper discusses the dosimetry methodology used to estimate bone marrow dose and the results of dosimetry calculations for 6,507 subjects in an epidemiologic case. control study of leukemia among Utah residents. The estimated doses were used to determine if a higher incidence of leukemia among residents of Utah could have been attributed to exposure to radioactive fallout from above-ground nuclear weapons tests conducted at the Nevada Test Site. The objective of the dosimetry methodology was to estimate absorbed dose to active marrow specific to each case and each control subject. Data on the residence of each subject were availablemore » from records of the Church of Jesus Christ of Latter-day Saints. Deposition of fallout was determined from databases developed using historical measurements and exposure for each subject from each test was estimated using those data. Exposure was converted to dose by applying an age-dependent dose conversion factor and a factor for shielding. The median dose for all case and control subjects was 3.2 mGy. The maximum estimated mean dose for any case or control was 29 {plus_minus} 5.6 mGy (a resident of Washington County, UT). Uncertainties were estimated for each estimated dose. The results of the dosimetry calculations were applied in an epidemiological analysis.« less

The Russian radiation legacy: its integrated impact and lessons.

PubMed

Goldman, M

1997-12-01

Information about the consequences of human exposure to radiation in the former Soviet Union has recently become available. These data add new insights and provide possible answers to several important questions regarding radiation and its impact on occupational and public health. The 1986 Chernobyl accident initiated a major and early increase in childhood thyroid cancer that resulted from ingestion of iodine-131 (131I) by young children living in the most heavily contaminated areas of Belarus, Ukraine, and Russia. No significant additional cancer or other adverse medical effects have yet been reported in the affected populations and among clean-up workers. Major psychological stress independent of radiation dose has been observed in those people thought to be exposed. During the early days of the atomic energy program in the former Soviet Union, some unfortunate events occurred. The country's first atomic test in Semipalatinsk in 1949 exposed over 25,000 people downwind from the blast to significant doses of fission products, especially 131I. During the late 1940s and the early 1950s nuclear material production facilities were developed near Chelyabinsk in the South Ural Mountains, which resulted in major releases into the environment and significant overexposures for thousands of workers and nearby populations. Chronic radiation sickness was observed early in exposed workers, and increases in leukemia and other cancers were also reported. The series of plutonium inhalation-related lung cancers and fatalities among workers exposed in that first decade appears to be unique. Long-term consequences of chronic radiation sickness and four decades of follow-up are being described for the first time. Villagers downstream from the plant consumed high levels of 137Cs and 90Sr and, it is reported, manifested increases in leukemia from internal and external exposures. Although the 40-year databases for retrospective dosimetry epidemiology studies are just beginning to be integrated and evaluated, preliminary evaluations suggest that there may be graded, significant dose-rate amelioration factors for cancer and leukemia risks in workers and the general population relative to the risk data on the Japanese atomic bomb survivors. Even for plutonium-induced lung cancers in workers, such a dose-rate effect may be evident. These experiences give us insight into the consequences of protracted radiation at high and low doses and rates. If these findings are validated and confirmed, they can provide information that reduces some of the uncertainties in retrospective radiation dosimetry and radiation risk estimates (especially for low-level, chronic exposures) for activities related to medicine as well as the handling of nuclear materials and nuclear facility decommissioning, decontamination, and demilitarization.

(⁹⁹m)Tc-MAA overestimates the absorbed dose to the lungs in radioembolization: a quantitative evaluation in patients treated with ¹⁶⁶Ho-microspheres.

PubMed

Elschot, Mattijs; Nijsen, Johannes F W; Lam, Marnix G E H; Smits, Maarten L J; Prince, Jip F; Viergever, Max A; van den Bosch, Maurice A A J; Zonnenberg, Bernard A; de Jong, Hugo W A M

2014-10-01

Radiation pneumonitis is a rare but serious complication of radioembolic therapy of liver tumours. Estimation of the mean absorbed dose to the lungs based on pretreatment diagnostic (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) imaging should prevent this, with administered activities adjusted accordingly. The accuracy of (99m)Tc-MAA-based lung absorbed dose estimates was evaluated and compared to absorbed dose estimates based on pretreatment diagnostic (166)Ho-microsphere imaging and to the actual lung absorbed doses after (166)Ho radioembolization. This prospective clinical study included 14 patients with chemorefractory, unresectable liver metastases treated with (166)Ho radioembolization. (99m)Tc-MAA-based and (166)Ho-microsphere-based estimation of lung absorbed doses was performed on pretreatment diagnostic planar scintigraphic and SPECT/CT images. The clinical analysis was preceded by an anthropomorphic torso phantom study with simulated lung shunt fractions of 0 to 30 % to determine the accuracy of the image-based lung absorbed dose estimates after (166)Ho radioembolization. In the phantom study, (166)Ho SPECT/CT-based lung absorbed dose estimates were more accurate (absolute error range 0.1 to -4.4 Gy) than (166)Ho planar scintigraphy-based lung absorbed dose estimates (absolute error range 9.5 to 12.1 Gy). Clinically, the actual median lung absorbed dose was 0.02 Gy (range 0.0 to 0.7 Gy) based on posttreatment (166)Ho-microsphere SPECT/CT imaging. Lung absorbed doses estimated on the basis of pretreatment diagnostic (166)Ho-microsphere SPECT/CT imaging (median 0.02 Gy, range 0.0 to 0.4 Gy) were significantly better predictors of the actual lung absorbed doses than doses estimated on the basis of (166)Ho-microsphere planar scintigraphy (median 10.4 Gy, range 4.0 to 17.3 Gy; p < 0.001), (99m)Tc-MAA SPECT/CT imaging (median 2.5 Gy, range 1.2 to 12.3 Gy; p < 0.001), and (99m)Tc-MAA planar scintigraphy (median 5.5 Gy, range 2.3 to 18.2 Gy; p < 0.001). In clinical practice, lung absorbed doses are significantly overestimated by pretreatment diagnostic (99m)Tc-MAA imaging. Pretreatment diagnostic (166)Ho-microsphere SPECT/CT imaging accurately predicts lung absorbed doses after (166)Ho radioembolization.

Hanford Environmental Dose Reconstruction Project

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

Cannon, S.D.; Finch, S.M.

1992-10-01

The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The independent Technical Steering Panel (TSP) provides technical direction. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates):Source Terms, Environmental Transport, Environmental Monitoring Data, Demography, Food Consumption, and Agriculture, and Environmental Pathways and Dose Estimates.

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.

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.

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.

A pharmacometric case study regarding the sensitivity of structural model parameter estimation to error in patient reported dosing times.

PubMed

Knights, Jonathan; Rohatagi, Shashank

2015-12-01

Although there is a body of literature focused on minimizing the effect of dosing inaccuracies on pharmacokinetic (PK) parameter estimation, most of the work centers on missing doses. No attempt has been made to specifically characterize the effect of error in reported dosing times. Additionally, existing work has largely dealt with cases in which the compound of interest is dosed at an interval no less than its terminal half-life. This work provides a case study investigating how error in patient reported dosing times might affect the accuracy of structural model parameter estimation under sparse sampling conditions when the dosing interval is less than the terminal half-life of the compound, and the underlying kinetics are monoexponential. Additional effects due to noncompliance with dosing events are not explored and it is assumed that the structural model and reasonable initial estimates of the model parameters are known. Under the conditions of our simulations, with structural model CV % ranging from ~20 to 60 %, parameter estimation inaccuracy derived from error in reported dosing times was largely controlled around 10 % on average. Given that no observed dosing was included in the design and sparse sampling was utilized, we believe these error results represent a practical ceiling given the variability and parameter estimates for the one-compartment model. The findings suggest additional investigations may be of interest and are noteworthy given the inability of current PK software platforms to accommodate error in dosing times.

Health effects models for nuclear power plant accident consequence analysis: Low LET radiation

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

Evans, J.S.

1990-01-01

This report describes dose-response models intended to be used in estimating the radiological health effects of nuclear power plant accidents. Models of early and continuing effects, cancers and thyroid nodules, and genetic effects are provided. Weibull dose-response functions are recommended for evaluating the risks of early and continuing health effects. Three potentially lethal early effects -- the hematopoietic, pulmonary, and gastrointestinal syndromes -- are considered. In addition, models are included for assessing the risks of several nonlethal early and continuing effects -- including prodromal vomiting and diarrhea, hypothyroidism and radiation thyroiditis, skin burns, reproductive effects, and pregnancy losses. Linear andmore » linear-quadratic models are recommended for estimating cancer risks. Parameters are given for analyzing the risks of seven types of cancer in adults -- leukemia, bone, lung, breast, gastrointestinal, thyroid, and other.'' The category, other'' cancers, is intended to reflect the combined risks of multiple myeloma, lymphoma, and cancers of the bladder, kidney, brain, ovary, uterus and cervix. Models of childhood cancers due to in utero exposure are also developed. For most cancers, both incidence and mortality are addressed. The models of cancer risk are derived largely from information summarized in BEIR III -- with some adjustment to reflect more recent studies. 64 refs., 18 figs., 46 tabs.« less

[Solar exposure time for sunburn in Mexican population].

PubMed

Castanedo Cázares, Juan Pablo; Torres Álvarez, Bertha; Sobrevilla Ondarza, Salvador; Ehnis Pérez, Adriana; Gordillo Moscoso, Antonio

2012-01-01

THe minimal erythemal dose (MED) quantifies an individual's sensitivity to UV radiation (UVR). To estimate it in our population and establish the time of exposure inducing it during daily activities would allow us to calculate risk intervals. From 2005-2012, the UV solar radiation was measured with terrestrial radiometry and compared to public UV index (UVI). We determined the MED in 90 individuals with the prevalent phototypes in Mexico (III, IV, V), and estimated the time needed for the development of sunburn. The average MED for phototype III was 39 (IC 95%: 35-42) mJ/cm2, for IV 48 (IC 95%:42-53) mJ/cm2, and for V was 84 (IC 95%:75-92) mJ/cm2 (ANOVA, p ≤ 0.001). Approximately, 80% of the daily UVR was accumulated between 10:00-16:00 h, and 77% of the annual UV dose is received between March-October. The public UVI had a high correlation with the one quantified at terrestrial level (r = 0.89; p ≤ 0.001). Mexico receives continuously high levels of UVR. Phototype III will present sunburn after 22-33 min in a summer day, while phototype V will require over one hour of exposure. This last group is at risk of chronic exposure without considering consequences.

Measurement of dose distribution in the spherical phantom onboard the ISS-KIBO module -MATROSHKA-R in KIBO-

NASA Astrophysics Data System (ADS)

Kodaira, Satoshi; Kawashima, Hajime; Kurano, Mieko; Uchihori, Yukio; Nikolaev, Igor; Ambrozova, Iva; Kitamura, Hisashi; Kartsev, Ivan; Tolochek, Raisa; Shurshakov, Vyacheslav

The measurement of dose equivalent and effective dose during manned space missions on the International Space Station (ISS) is important for evaluating the risk to astronaut health and safety when exposed to space radiation. The dosimetric quantities are constantly changing and strongly depend on the level of solar activity and the various spacecraft- and orbit-dependent parameters such as the shielding distribution in the ISS module, location of the spacecraft within its orbit relative to the Earth, the attitude (orientation) and altitude. Consequently, the continuous monitoring of dosimetric quantities is required to record and evaluate the personal radiation dose for crew members during spaceflight. The dose distributions in the phantom body and on its surface give crucial information to estimate the dose equivalent in the human body and effective dose in manned space mission. We have measured the absorbed dose and dose equivalent rates using passive dosimeters installed in the spherical phantom in Japanese Experiment Module (“KIBO”) of the ISS in the framework of Matroshka-R space experiment. The exposure duration was 114 days from May 21 to September 12, 2012. The phantom consists of tissue-equivalent material covered with a poncho jacket with 32 pockets on its surface and 20 container rods inside of the phantom. The phantom diameter is 35 cm and the mass is 32 kg. The passive dosimeters consisted of a combination of luminescent detectors of Al _{2}O _{3};C OSL and CaSO _{4}:Dy TLD and CR-39 plastic nuclear track detectors. As one of preliminary results, the dose distribution on the phantom surface measured with OSL detectors installed in the jacket pockets is found to be ranging from 340 muGy/day to 260 muGy/day. In this talk, we will present the detail dose distributions, and variations of LET spectra and quality factor obtained outside and inside of the spherical phantom installed in the ISS-KIBO.

German cardiac CT registry: indications, procedural data and clinical consequences in 7061 patients undergoing cardiac computed tomography.

PubMed

Marwan, Mohamed; Achenbach, Stephan; Korosoglou, Grigorios; Schmermund, Axel; Schneider, Steffen; Bruder, Oliver; Hausleiter, Jörg; Schroeder, Stephen; Barth, Sebastian; Kerber, Sebastian; Leber, Alexander; Moshage, Werner; Senges, Jochen

2018-05-01

Cardiac computed tomography permits quantification of coronary calcification as well as detection of coronary artery stenoses after contrast enhancement. Moreover, cardiac CT offers high-resolution morphologic and functional imaging of cardiac structures which is valuable for various structural heart disease interventions and electrophysiology procedures. So far, only limited data exist regarding the spectrum of indications, image acquisition parameters as well as results and clinical consequences of cardiac CT examinations using state-of-the-art CT systems in experienced centers. Twelve cardiology centers with profound expertise in cardiovascular imaging participated in the German Cardiac CT Registry. Criteria for participation included adequate experience in cardiac CT as well of the availability of a 64-slice or newer CT system. Between 2009 and 2014, 7061 patients were prospectively enrolled. For all cardiac CT examinations, patient parameters, procedural data, indication and clinical consequences of the examination were documented. Mean patient age was 61 ± 12 years, 63% were males. The majority (63%) of all cardiac CT examinations were performed in an outpatient setting, 37% were performed during an inpatient stay. 91% were elective and 9% were scheduled in an acute setting. In most examinations (48%), reporting was performed by cardiologists, in 4% by radiologists and in 47% of the cases as a consensus reading. Cardiac CT was limited to native acquisitions for assessment of coronary artery calcification in 9% of patients, only contrast-enhanced coronary CT angiography was performed in 16.6% and combined native and contrast-enhanced coronary CT angiography was performed in 57.7% of patients. Non-coronary cardiac CT examinations constituted 16.6% of all cases. Coronary artery calcification assessment was performed using prospectively ECG-triggered acquisition in 76.9% of all cases. The median dose length product (DLP) was 42 mGy cm (estimated effective radiation dose of 0.6 mSv). Coronary CT angiography was performed using prospectively ECG-triggered acquisition in 77.3% of all cases. Tube voltage was 120 kV in 67.8% of patients and 100 kV in 30.7% of patients, with a resultant median DLP of 256 mGy cm (estimated effective dose of 3.6 mSv). Clinical consequences of cardiac CT were as follows: in 46.8% of the cases, invasive coronary angiography could be avoided; ischemia testing was recommended in 4.7% of the cases, invasive coronary angiography was recommended in 16.4% of the cases and change in medication in 21.6% of the examinations. Cardiac CT is performed in the majority of patients for non-invasive evaluation of the coronary arteries. CT frequently resulted in medication change, and otherwise planned downstream testing including invasive angiography could be avoided in a high percentage of patients. Radiation exposure in experienced centers is relatively low.

Space: The Final Frontier-Research Relevant to Mars.

PubMed

Boice, John D

2017-04-01

A critically important gap in knowledge surrounds the health consequences of exposure to radiation received gradually over time. Much is known about the health effects of brief high-dose exposures, such as from the atomic bombings in Japan, but the concerns today focus on the frequent low-dose exposures received by members of the public, workers, and, as addressed in this paper, astronauts. Additional guidance is needed by the National Aeronautics and Space Administration (NASA) for planning long-term missions where the rate of radiation exposure is gradual over years and the cumulative amounts high. The direct study of low doses and low-dose rates is of immeasurable value in understanding the possible range of health effects from gradual exposures and in providing guidance for radiation protection, not only of workers and the public but also astronauts. The ongoing Million Person Study (MPS) is 10 times larger than the study of the Japanese atomic bomb survivors of 86,000 survivors with estimated doses. The number of workers with >100 mSv career dose is substantially greater. The large study size, broad range of doses, and long follow-up indicate substantial statistical ability to quantify the risk of exposures that are received gradually over time. The study consists of 360,000 U.S. Department of Energy workers from the Manhattan Project; 150,000 nuclear utility workers from the inception of the nuclear age; 115,000 atomic veterans who participated in above-ground atmospheric tests at the Nevada Test Site and the Bikini and Enewetak Atolls and Johnston Island in the Pacific Proving Grounds (PPG); 250,000 radiologists and medical workers; and 130,000 industrial radiographers. NASA uses an individual risk-based system for radiation protection in contrast to the system of dose limits for occupational exposures used by terrestrial-based organizations. The permissible career exposure limit set by NASA for each astronaut is a 3% risk of exposure-induced death (REID) from cancer at a 95% confidence level to account for uncertainties in risk projections. The large size of the MPS will reduce the uncertainty in the risk estimates, narrowing the 95% confidence interval, and thus allow more time in space for astronauts. Further differences between men and women in their response to radiation can be more fully examined, and non-cancer outcomes, such as neurological disorders and cardiovascular disease, can be evaluated in a way not hitherto possible.

Application of the Bulgarian emergency response system in case of nuclear accident in environmental assessment study

NASA Astrophysics Data System (ADS)

Syrakov, Dimiter; Veleva, Blagorodka; Georgievs, Emilia; Prodanova, Maria; Slavov, Kiril; Kolarova, Maria

2014-05-01

The development of the Bulgarian Emergency Response System (BERS) for short term forecast in case of accidental radioactive releases to the atmosphere has been started in the mid 1990's [1]. BERS comprises of two main parts - operational and accidental, for two regions 'Europe' and 'Northern Hemisphere'. The operational part runs automatically since 2001 using the 72 hours meteorological forecast from DWD Global model, resolution in space of 1.5o and in time - 12 hours. For specified Nuclear power plants (NPPs), 3 days trajectories are calculated and presented on NIMH's specialized Web-site (http://info.meteo.bg/ews/). The accidental part is applied when radioactive releases are reported or in case of emergency exercises. BERS is based on numerical weather forecast information and long-range dispersion model accounting for the transport, dispersion, and radioactive transformations of pollutants. The core of the accidental part of the system is the Eulerian 3D dispersion model EMAP calculating concentration and deposition fields [2]. The system is upgraded with a 'dose calculation module' for estimation of the prognostic dose fields of 31 important radioactive gaseous and aerosol pollutants. The prognostic doses significant for the early stage of a nuclear accident are calculated as follows: the effective doses from external irradiation (air submersion + ground shinning); effective dose from inhalation; summarized effective dose and absorbed thyroid dose [3]. The output is given as 12, 24, 36, 48, 60 and 72 hours prognostic dose fields according the updated meteorology. The BERS was upgraded to simulate the dispersion of nuclear materials from Fukushima NPP [4], and results were presented in NIMH web-site. In addition BERS took part in the respective ENSEMBLE exercises to model 131I and 137Cs in Fukushima source term. In case of governmental request for expertise BERS was applied for environmental impact assessment of hypothetical accidental transboundary radioactive pollution. The consequences were estimated based on the worst emission scenario for the existing basic reactor type, selection of real meteorological forecast conditions, favoring the direct transport of the contaminated air masses to the territory of the country in consideration. In the present work BERS is used to estimate the worst case accidental scenario impact from a possible new unit of Paks Nuclear Power Plant, Hungary over the territory of Bulgaria. 1. D.Syrakov, M.Prodanova, 1998, Atmospheric Environment, 32 (24), 4367-4375. 2. D. Syrakov, M. Prodanova, K. Slavov, Inernationsal J. Environment and Pollution, 20, 1-6 (2003) 286-296. 3. D. Syrakov, B. Veleva, M. Prodanova, T. Popova, M. Kolarova, Journal of Environmental Radioactivity 100 (2009) 151-156. 4. D.Syrakov, M Prodanova, J. Intern. Sci. Publ.: Ecology & Safety Vol. 6 Part 1 (2011) 94-102. www.scientific-publications.net.

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...

Linear No-Threshold Model VS. Radiation Hormesis

PubMed Central

Doss, Mohan

2013-01-01

The atomic bomb survivor cancer mortality data have been used in the past to justify the use of the linear no-threshold (LNT) model for estimating the carcinogenic effects of low dose radiation. An analysis of the recently updated atomic bomb survivor cancer mortality dose-response data shows that the data no longer support the LNT model but are consistent with a radiation hormesis model when a correction is applied for a likely bias in the baseline cancer mortality rate. If the validity of the phenomenon of radiation hormesis is confirmed in prospective human pilot studies, and is applied to the wider population, it could result in a considerable reduction in cancers. The idea of using radiation hormesis to prevent cancers was proposed more than three decades ago, but was never investigated in humans to determine its validity because of the dominance of the LNT model and the consequent carcinogenic concerns regarding low dose radiation. Since cancer continues to be a major health problem and the age-adjusted cancer mortality rates have declined by only ∼10% in the past 45 years, it may be prudent to investigate radiation hormesis as an alternative approach to reduce cancers. Prompt action is urged. PMID:24298226

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.

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.

Hanford Environmental Dose Reconstruction Project. Monthly report

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

Cannon, S.D.; Finch, S.M.

1992-10-01

The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The independent Technical Steering Panel (TSP) provides technical direction. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates):Source Terms, Environmental Transport, Environmental Monitoring Data, Demography, Food Consumption, and Agriculture, and Environmental Pathways and Dose Estimates.

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

Statistical methods for biodosimetry in the presence of both Berkson and classical measurement error

NASA Astrophysics Data System (ADS)

Miller, Austin

In radiation epidemiology, the true dose received by those exposed cannot be assessed directly. Physical dosimetry uses a deterministic function of the source term, distance and shielding to estimate dose. For the atomic bomb survivors, the physical dosimetry system is well established. The classical measurement errors plaguing the location and shielding inputs to the physical dosimetry system are well known. Adjusting for the associated biases requires an estimate for the classical measurement error variance, for which no data-driven estimate exists. In this case, an instrumental variable solution is the most viable option to overcome the classical measurement error indeterminacy. Biological indicators of dose may serve as instrumental variables. Specification of the biodosimeter dose-response model requires identification of the radiosensitivity variables, for which we develop statistical definitions and variables. More recently, researchers have recognized Berkson error in the dose estimates, introduced by averaging assumptions for many components in the physical dosimetry system. We show that Berkson error induces a bias in the instrumental variable estimate of the dose-response coefficient, and then address the estimation problem. This model is specified by developing an instrumental variable mixed measurement error likelihood function, which is then maximized using a Monte Carlo EM Algorithm. These methods produce dose estimates that incorporate information from both physical and biological indicators of dose, as well as the first instrumental variable based data-driven estimate for the classical measurement error variance.

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 Medical Systems; Consultant, Samsung Electronics.« less

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

Ene, D.; Andersson, K.; Jensen, M.

The European Spallation Source (ESS) will produce tritium via spallation and activation processes during operational activities. Within the location of ESS facility in Lund, Sweden site it is mandatory to demonstrate that the management strategy of the produced tritium ensures the compliance with the country regulation criteria. The aim of this paper is to give an overview of the different aspects of the tritium management in ESS facility. Besides the design parameter study of the helium coolant purification system of the target the consequences of the tritium releasing into the environment were also analyzed. Calculations show that the annual releasemore » of tritium during the normal operations represents a small fraction from the estimated total dose. However, more refined calculations of migration of activated-groundwater should be performed for higher hydraulic conductivities, with the availability of the results on soil examinations. With the assumption of 100% release of tritium to the atmosphere during the occurring of the extreme accidents, it was found as well that the total dose complies with the constraint. (authors)« less

Severity of killer whale behavioral responses to ship noise: a dose-response study.

PubMed

Williams, Rob; Erbe, Christine; Ashe, Erin; Beerman, Amber; Smith, Jodi

2014-02-15

Critical habitats of at-risk populations of northeast Pacific "resident" killer whales can be heavily trafficked by large ships, with transits occurring on average once every hour in busy shipping lanes. We modeled behavioral responses of killer whales to ship transits during 35 "natural experiments" as a dose-response function of estimated received noise levels in both broadband and audiogram-weighted terms. Interpreting effects is contingent on a subjective and seemingly arbitrary decision about severity threshold indicating a response. Subtle responses were observed around broadband received levels of 130 dB re 1 μPa (rms); more severe responses are hypothesized to occur at received levels beyond 150 dB re 1 μPa, where our study lacked data. Avoidance responses are expected to carry minor energetic costs in terms of increased energy expenditure, but future research must assess the potential for reduced prey acquisition, and potential population consequences, under these noise levels. Copyright © 2013 Elsevier Ltd. All rights reserved.

Are Evidence Standards Different for Genomic- vs. Clinical-Based Precision Medicine? A Quantitative Analysis of Individualized Warfarin Therapy.

PubMed

Dhanda, D S; Guzauskas, G F; Carlson, J J; Basu, A; Veenstra, D L

2017-11-01

Evidence requirements for implementation of precision medicine (PM), whether informed by genomic or clinical data, are not well defined. Evidence requirements are driven by uncertainty and its attendant consequences; these aspects can be quantified by a novel technique in health economics: value of information analysis (VOI). We utilized VOI analysis to compare the evidence levels over time for warfarin dosing based on pharmacogenomic vs. amiodarone-warfarin drug-drug interaction information. The primary outcome was the expected value of perfect information (EVPI), which is an estimate of the upper limit of the societal value of conducting future research. Over the past decade, the EVPI for the pharmacogenomic strategy decreased from $1,550 to $140 vs. $1,220 to $280 per patient for the drug-interaction strategy. Evidence levels thus appear to be higher for pharmacogenomic-guided vs. drug-interaction-guided warfarin dosing. Clinical guidelines and reimbursement policies for warfarin PM could be informed by these findings. © 2017 American Society for Clinical Pharmacology and Therapeutics.

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...

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...

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.

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 (D90) agreeing within ±3%, on average. Conclusions: Several aspects of OLINDA/EXM dose calculation were compared with patient-specific dose estimates obtained using Monte Carlo. Differences in patient anatomy led to large differences in cross-organ doses. However, total organ doses were still in good agreement since most of the deposited dose is due to self-irradiation. Comparison of voxelized doses calculated by Monte Carlo and the voxel S value technique showed that the 3D dose distributions produced by the respective methods are nearly identical.« less

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.

Consequences of synergy between environmental carcinogens

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

Berenbaum, M.C.

1985-12-01

As it is generally impossible to determine dose-response relationships for carcinogens at the low concentrations in which they occur in the environment, risk-benefit considerations are by consensus based on the linear, no-threshold model, on the assumption that this represents the worst case. However, this assumption does not take into account the possibility of synergistic interactions between carcinogens. It is shown here that, as a result of such interactions, the dose-response curve for added risk due to any individual carcinogen will generally be steeper at lower doses than at higher doses, and consequently the risk at low environmental levels will bemore » higher than would be expected from a linear response. Moreover, this excess risk at low doses is shown to increase as the general level of environmental carcinogens rises and, independently of this effect, it may also increase with the number of carcinogens present.« less

A cost effectiveness analysis of thiopurine methyltransferase testing for guiding 6-mercaptopurine dosing in children with acute lymphoblastic leukemia.

PubMed

Donnan, Jennifer R; Ungar, Wendy J; Mathews, Maria; Hancock-Howard, Rebecca L; Rahman, Proton

2011-08-01

An increased understanding of the genetic basis of disease creates a demand for personalized medicine and more genetic testing for diagnosis and treatment. The objective was to assess the incremental cost-effectiveness per life-month gained of thiopurine methyltransferase (TPMT) genotyping to guide doses of 6-mercaptopurine (6-MP) in children with acute lymphoblastic leukemia (ALL) compared to enzymatic testing and standard weight-based dosing. A cost-effectiveness analysis was conducted from a health care system perspective comparing costs and consequences over 3 months. Decision analysis was used to evaluate the impact of TPMT tests on preventing myelosuppression and improving survival in ALL patients receiving 6-MP. Direct medical costs included laboratory tests, medications, physician services, pharmacy and inpatient care. Probabilities were derived from published evidence. Survival was measured in life-months. The robustness of the results to variable uncertainty was tested in one-way sensitivity analyses. Probabilistic sensitivity analysis examined the impact of parameter uncertainty and generated confidence intervals around point estimates. Neither of the testing interventions showed a benefit in survival compared to weight-based dosing. Both test strategies were more costly compared to weight-based dosing. Incremental costs per child (95% confidence interval) were $277 ($112, $442) and $298 ($392, $421) for the genotyping and phenotyping strategies, respectively, compared to weight-based dosing. The present analysis suggests that screening for TPMT mutations using either genotype or enzymatic laboratory tests prior to the administration of 6-MP in pediatric ALL patients is not cost-effective. Copyright © 2011 Wiley-Liss, Inc.

The Need for Antiepileptic Drug Chronotherapy to Treat Selected Childhood Epilepsy Syndromes and Avert the Harmful Consequences of Drug Resistance

PubMed Central

Manganaro, Sheryl; Loddenkemper, Tobias; Rotenberg, Alexander

2017-01-01

Antiepileptic drug (AED) chronotherapy involves the delivery of a greater AED dose at the time of greatest seizure susceptibility usually associated with predictable seizure peaks. Although research has proven AED chronotherapy, commonly known as differential dosing, to be safe, well tolerated, and highly effective in managing cyclic seizure patterns in selected childhood epilepsies, conventional, equally divided AED dosing remains the standard of care. Differential dosing is more often applied in the emergency management of acute seizure clustering resulting from drug resistance—a harmful epilepsy-related consequence that affects 30% of children. Moreover, drug resistance is a major risk factor in status epilepticus and sudden, unexpected death in epilepsy. Although these facts should promote the wider use of differential dosing in selected cases, a credible hypothesis is needed that defines the differential dosing strategy and application in cyclic epilepsy and for the greater purpose of preventing harmful outcomes. PMID:29308021

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...

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.

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. © RSNA, 2013.

[Radiation conditions and radiation risks for cosmonauts flying to Mars using electrical jet microthrusters].

PubMed

Shafirkin, A V; Kolomenskiĭ, A V

2008-01-01

According to recent workups, the Mars mission spacecraft will be designed with an electrical jet microthrusters rather than a power reactor facility. The article contains analysis of the main sources of radiation hazard during the exploration mission using this cost-efficient, ecological, easy-to-operate propulsion powered by solar arrays. In addition, the authors make predictions of the generalized doses of ionizing radiation for mission durations of 730 and 900 days behind various shielding thicknesses, and on the Martian surface. Calculation algorithms are described and radiation risks are estimated for the crew life span and possible life time reduction in consequence of participation in the mission.

A summary of evidence on radiation exposures received near to the Semipalatinsk nuclear weapons test site in Kazakhstan.

PubMed

Simon, Steven L; Baverstock, Keith F; Lindholm, Carita

2003-06-01

The presently available evidence about the magnitude of doses received by members of the public living in villages in the vicinity of Semipalatinsk nuclear test in Kazakhstan, particularly with respect to external radiation, while preliminary, is conflicting. The village of Dolon, in particular, has been identified for many years as the most highly exposed location in the vicinity of the test site. Previous publications cited external doses of more than 2 Gy to residents of Dolon while an expert group assembled by the WHO in 1997 estimated that external doses were likely to have been less than 0.5 Gy. In 2001, a larger expert group workshop was held in Helsinki jointly by the WHO, the National Cancer Institute of the United States, and the Radiation and Nuclear Safety Authority of Finland, with the expressed purpose to acquire data to evaluate the state of knowledge concerning doses received in Kazakhstan. This paper summarizes evidence presented at that workshop. External dose estimates from calculations based on sparse physical measurements and bio-dosimetric estimates based on chromosome abnormalities and electron paramagnetic resonance from a relatively small sample of teeth do not agree well. The physical dose estimates are generally higher than the biodosimetric estimates (1 Gy or more compared to 0.5 Gy or less). When viewed in its entirety, the present body of evidence does not appear to support external doses greater than 0.5 Gy; however, research is continuing to try and resolve the difference in dose estimates from the different methods. Thyroid doses from internal irradiation, which can only be estimated via calculation, are expected to have been several times greater than the doses from external irradiation, especially where received by small children.

Assessment of radiation doses from residential smoke detectors that contain americium-241

NASA Astrophysics Data System (ADS)

Odonnell, F. R.; Etnier, E. L.; Holton, G. A.; Travis, C. C.

1981-10-01

External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv to 20 nSv for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 micro-Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 micro-Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft squared.

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

Accounting for shared and unshared dosimetric uncertainties in the dose response for ultrasound-detected thyroid nodules after exposure to radioactive fallout.

PubMed

Land, Charles E; Kwon, Deukwoo; Hoffman, F Owen; Moroz, Brian; Drozdovitch, Vladimir; Bouville, André; Beck, Harold; Luckyanov, Nicholas; Weinstock, Robert M; Simon, Steven L

2015-02-01

Dosimetic uncertainties, particularly those that are shared among subgroups of a study population, can bias, distort or reduce the slope or significance of a dose response. Exposure estimates in studies of health risks from environmental radiation exposures are generally highly uncertain and thus, susceptible to these methodological limitations. An analysis was published in 2008 concerning radiation-related thyroid nodule prevalence in a study population of 2,994 villagers under the age of 21 years old between August 1949 and September 1962 and who lived downwind from the Semipalatinsk Nuclear Test Site in Kazakhstan. This dose-response analysis identified a statistically significant association between thyroid nodule prevalence and reconstructed doses of fallout-related internal and external radiation to the thyroid gland; however, the effects of dosimetric uncertainty were not evaluated since the doses were simple point "best estimates". In this work, we revised the 2008 study by a comprehensive treatment of dosimetric uncertainties. Our present analysis improves upon the previous study, specifically by accounting for shared and unshared uncertainties in dose estimation and risk analysis, and differs from the 2008 analysis in the following ways: 1. The study population size was reduced from 2,994 to 2,376 subjects, removing 618 persons with uncertain residence histories; 2. Simulation of multiple population dose sets (vectors) was performed using a two-dimensional Monte Carlo dose estimation method; and 3. A Bayesian model averaging approach was employed for evaluating the dose response, explicitly accounting for large and complex uncertainty in dose estimation. The results were compared against conventional regression techniques. The Bayesian approach utilizes 5,000 independent realizations of population dose vectors, each of which corresponds to a set of conditional individual median internal and external doses for the 2,376 subjects. These 5,000 population dose vectors reflect uncertainties in dosimetric parameters, partly shared and partly independent, among individual members of the study population. Risk estimates for thyroid nodules from internal irradiation were higher than those published in 2008, which results, to the best of our knowledge, from explicitly accounting for dose uncertainty. In contrast to earlier findings, the use of Bayesian methods led to the conclusion that the biological effectiveness for internal and external dose was similar. Estimates of excess relative risk per unit dose (ERR/Gy) for males (177 thyroid nodule cases) were almost 30 times those for females (571 cases) and were similar to those reported for thyroid cancers related to childhood exposures to external and internal sources in other studies. For confirmed cases of papillary thyroid cancers (3 in males, 18 in females), the ERR/Gy was also comparable to risk estimates from other studies, but not significantly different from zero. These findings represent the first reported dose response for a radiation epidemiologic study considering all known sources of shared and unshared errors in dose estimation and using a Bayesian model averaging (BMA) method for analysis of the dose response.

SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

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

Supanich, MP

2015-06-15

Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in themore » central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG.« less

The pharmacokinetics of ketoconazole and its effects on the pharmacokinetics of midazolam and fentanyl in dogs.

PubMed

KuKanich, B; Hubin, M

2010-02-01

Ketoconazole inhibits the Cytochrome P450 3A12 (CYP3A12) metabolizing enzyme as well as the p-glycoprotein efflux pump. The extent and clinical consequence of these effects are poorly understood in dogs. The objective was to assess the pharmacokinetics of ketoconazole after single and multiple doses and the effect of multiple doses of ketoconazole on midazolam (a known CYP3A12 substrate) and the opioid fentanyl. Six greyhound dogs were studied. The study consisted of three phases. Phase 1 consisted of i.v. midazolam (0.23 mg/kg base) and fentanyl (15.71 microg/kg base). Phase 2 consisted of a single oral dose of ketoconazole (mean dose 12.34 mg/kg). Phase 3 consisted of i.v. midazolam (0.23 mg/kg) and fentanyl (10 microg/kg) after 5 days of oral ketoconazole (12.25 mg/kg/day). Ketoconazole significantly inhibited its own elimination with the mean residence time (MRT) increasing from 6.24 h in Phase 1 to 12.54 h in Phase 3. Ketoconazole significantly decreased the elimination of midazolam, as expected, with the MRT increasing from 0.81 to 1.49 h. The elimination of fentanyl was not significantly altered by co-administration of ketoconazole with the MRT being 3.90 and 6.35 h. The MRT was the most robust estimate of decreased drug elimination.

Radiological assessment. A textbook on environmental dose analysis

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

Till, J.E.; Meyer, H.R.

1983-09-01

Radiological assessment is the quantitative process of estimating the consequences to humans resulting from the release of radionuclides to the biosphere. It is a multidisciplinary subject requiring the expertise of a number of individuals in order to predict source terms, describe environmental transport, calculate internal and external dose, and extrapolate dose to health effects. Up to this time there has been available no comprehensive book describing, on a uniform and comprehensive level, the techniques and models used in radiological assessment. Radiological Assessment is based on material presented at the 1980 Health Physics Society Summer School held in Seattle, Washington. Themore » material has been expanded and edited to make it comprehensive in scope and useful as a text. Topics covered include (1) source terms for nuclear facilities and Medical and Industrial sites; (2) transport of radionuclides in the atmosphere; (3) transport of radionuclides in surface waters; (4) transport of radionuclides in groundwater; (5) terrestrial and aquatic food chain pathways; (6) reference man; a system for internal dose calculations; (7) internal dosimetry; (8) external dosimetry; (9) models for special-case radionuclides; (10) calculation of health effects in irradiated populations; (11) evaluation of uncertainties in environmental radiological assessment models; (12) regulatory standards for environmental releases of radionuclides; (13) development of computer codes for radiological assessment; and (14) assessment of accidental releases of radionuclides.« less

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.

An influential factor for external radiation dose estimation for residents after the Fukushima Daiichi Nuclear Power Plant accident-time spent outdoors for residents in Iitate Village.

PubMed

Ishikawa, Tetsuo; Yasumura, Seiji; Ohtsuru, Akira; Sakai, Akira; Akahane, Keiichi; Yonai, Shunsuke; Sakata, Ritsu; Ozasa, Kotaro; Hayashi, Masayuki; Ohira, Tetsuya; Kamiya, Kenji; Abe, Masafumi

2016-06-01

Many studies have been conducted on radiation doses to residents after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Time spent outdoors is an influential factor for external dose estimation. Since little information was available on actual time spent outdoors for residents, different values of average time spent outdoors per day have been used in dose estimation studies on the FDNPP accident. The most conservative value of 24 h was sometimes used, while 2.4 h was adopted for indoor workers in the UNSCEAR 2013 report. Fukushima Medical University has been estimating individual external doses received by residents as a part of the Fukushima Health Management Survey by collecting information on the records of moves and activities (the Basic Survey) after the accident from each resident. In the present study, these records were analyzed to estimate an average time spent outdoors per day. As an example, in Iitate Village, its arithmetic mean was 2.08 h (95% CI: 1.64-2.51) for a total of 170 persons selected from respondents to the Basic Survey. This is a much smaller value than commonly assumed. When 2.08 h is used for the external dose estimation, the dose is about 25% (23-26% when using the above 95% CI) less compared with the dose estimated for the commonly used value of 8 h.

[The concept of risk and its estimation].

PubMed

Zocchetti, C; Della Foglia, M; Colombi, A

1996-01-01

The concept of risk, in relation to human health, is a topic of primary interest for occupational health professionals. A new legislation recently established in Italy (626/94) according to European Community directives in the field of Preventive Medicine, called attention to this topic, and in particular to risk assessment and evaluation. Motivated by this context and by the impression that the concept of risk is frequently misunderstood, the present paper has two aims: the identification of the different meanings of the term "risk" in the new Italian legislation and the critical discussion of some commonly used definitions; and the proposal of a general definition, with the specification of a mathematical expression for quantitative risk estimation. The term risk (and risk estimation, assessment, or evaluation) has mainly referred to three different contexts: hazard identification, exposure assessment, and adverse health effects occurrence. Unfortunately, there are contexts in the legislation in which it is difficult to identify the true meaning of the term. This might cause equivocal interpretations and erroneous applications of the law because hazard evaluation, exposure assessment, and adverse health effects identification are completely different topics that require integrated but distinct approaches to risk management. As far as a quantitative definition of risk is of concern, we suggest an algorithm which connects the three basic risk elements (hazard, exposure, adverse health effects) by means of their probabilities of occurrence: the probability of being exposed (to a definite dose) given that a specific hazard is present (Pr(e[symbol: see text]p)), and the probability of occurrence of an adverse health effect as a consequence of that exposure (Pr(d[symbol: see text]e)). Using these quantitative components, risk can be defined as a sequence of measurable events that starts with hazard identification and terminates with disease occurrence; therefore, the following formal definition of risk is proposed: the probability of occurrence, in a given period of time, of an adverse health effect as a consequence of the existence of an hazard. In formula: R(d[symbol: see text]p) = Pr(e[symbol: see text]p) x Pr(d[symbol: see text]e). While Pr(e[symbol: see text]p) (exposure given hazard) must be evaluated in the situation under study, two alternatives exist for the estimation of the occurrence of adverse health effects (Pr(d[symbol: see text]e)): a "direct" estimation of the damage (Pr(d[symbol: see text]e) through formal epidemiologic studies conducted in the situation under observation; and an "indirect" estimation of Pr(d[symbol: see text]e) using information taken from the scientific literature (epidemiologic evaluations, dose-response relationships, extrapolations, ...). Both conditions are presented along with their respective advantages, disadvantages, and uncertainties. The usefulness of the proposed algorithm is discussed with respect to commonly used applications of risk assessment in occupational medicine; the relevance of time for risk estimation (both in the term of duration of observation, duration of exposure, and latency of effect) is briefly explained; and how the proposed algorithm takes into account (in terms of prevention and public health) both the etiologic relevance of the exposure and the consequences of exposure removal is highlighted. As a last comment, it is suggested that the diffuse application of good work practices (technical, behavioral, organizational, ...), or the exhaustive use of check lists, can be relevant in terms of improvement of prevention efficacy, but does not represent any quantitative procedure of risk assessment which, in any circumstance, must be considered the elective approach to adverse health effect prevention.

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

Acute toxicity, biochemical and histopathological responses of endosulfan in Chanos chanos.

PubMed

Kumar, Neeraj; Ambasankar, K; Krishnani, K K; Gupta, S K; Bhushan, Shashi; Minhas, P S

2016-09-01

This study investigated 96h median lethal concentration of endosulfan (99%, pure α: β ratio of 7:3) by conducting static non-renewable acute toxicity bio-assay in Chanos chanos juvenile with average weight (110±5.65g). Further, the effect of different definitive doses (18.5, 19.5, 20.5, 21.5 and 22.5µg/L) of endosulfan on metabolic, heamato-immunoligcal and histopathological response were probed. Anti-oxidative enzymes CAT, SOD and GST showed significant (p<0.01) increase of activity in the liver, gill and brain during exposure to endosulfan in a dose and time dependent manner. The brain AChE activity showed significant (p<0.01) inhibition from 18.5 to 22.5µg/L exposure of endosulfan than the control group. LDH and MDH activity gradually increased with consequent increasing dose of endosulfan exposure in the liver, gill and brain. Similarly, ALT, AST and G6PDH activities in both liver and gill increased with consequent increases in the dose of endosulfan exposure. Immunological profile such as blood glucose and serum cortisol level significantly enhanced while respiratory burst activity declined with consequent increasing doses of endosulfan exposure. Histopathological alteration in the gill demonstrated curling of secondary lamellae, thickening of primary epithelium, shorting of secondary lamellae, epithelial hyperplasia, fusion of secondary lamellae, aneurism, and collapsed secondary lamellae due to dose dependent exposure of endosulfan. Liver histology illustrated cloudy swelling and necrosis with pyknotic nuclei to the moderate dose of endosulfan, whereas higher dose of endosulfan (21.5µg/L) displayed severe necrosis of hepatic cells. Overall results clearly indicate that acute exposure of endosulfan led to pronounced deleterious alterations on biochemical, heamato-immunological, and histopathological responses of C. chanos juvenile. Copyright © 2016 Elsevier Inc. All rights reserved.

Assessment of simulated high-dose partial-body irradiation by PCC-R assay.

PubMed

Romero, Ivonne; García, Omar; Lamadrid, Ana I; Gregoire, Eric; González, Jorge E; Morales, Wilfredo; Martin, Cécile; Barquinero, Joan-Francesc; Voisin, Philippe

2013-09-01

The estimation of the dose and the irradiated fraction of the body is important information in the primary medical response in case of a radiological accident. The PCC-R assay has been developed for high-dose estimations, but little attention has been given to its applicability for partial-body irradiations. In the present work we estimated the doses and the percentage of the irradiated fraction in simulated partial-body radiation exposures at high doses using the PCC-R assay. Peripheral whole blood of three healthy donors was exposed to doses from 0-20 Gy, with ⁶⁰Co gamma radiation. To simulate partial body irradiations, irradiated and non-irradiated blood was mixed to obtain proportions of irradiated blood from 10-90%. Lymphocyte cultures were treated with Colcemid and Calyculin-A before harvest. Conventional and triage scores were performed for each dose, proportion of irradiated blood and donor. The Papworth's u test was used to evaluate the PCC-R distribution per cell. A dose-response relationship was fitted according to the maximum likelihood method using the frequencies of PCC-R obtained from 100% irradiated blood. The dose to the partially irradiated blood was estimated using the Contaminated Poisson method. A new D₀ value of 10.9 Gy was calculated and used to estimate the initial fraction of irradiated cells. The results presented here indicate that by PCC-R it is possible to distinguish between simulated partial- and whole-body irradiations by the u-test, and to accurately estimate the dose from 10-20 Gy, and the initial fraction of irradiated cells in the interval from 10-90%.

Biological dosimetry in a group of radiologists by the analysis of dicentrics and translocations.

PubMed

Montoro, A; Rodríguez, P; Almonacid, M; Villaescusa, J I; Verdú, G; Caballín, M R; Barrios, L; Barquinero, J F

2005-11-01

The results of a cytogenetic study carried out in a group of nine radiologists are presented. Chromosome aberrations were detected by fluorescence plus Giemsa staining and fluorescence in situ hybridization. Dose estimates were obtained by extrapolating the yield of dicentrics and translocations to their respective dose-effect curves. In seven individuals, the 95% confidence limits of the doses estimated by dicentrics did not include 0 Gy. The 99 dicentrics observed in 17,626 cells gave a collective estimated dose of 115 mGy (95% confidence limits 73-171). For translocations, five individuals had estimated doses that were clearly higher than the total accumulated recorded dose. The 82 total apparently simple translocations observed in 9722 cells gave a collective estimated dose of 275 mGy (132-496). The mean genomic frequencies (x100 +/- SE) of complete and total apparently simple translocations observed in the group of radiologists (1.91 +/- 0.30 and 2.67 +/- 0.34, respectively) were significantly higher than those observed in a matched control group (0.53 +/- 0.10 and 0.87 +/- 0.13, P < 0.01 in both cases) and in another occupationally exposed matched group (0.79 +/- 0.12 and 1.14 +/-0.14, P < 0.03 and P < 0.01, respectively). The discrepancies observed between the physically recorded doses and the biologically estimated doses indicate that the radiologists did not always wear their dosimeters or that the dosimeters were not always in the radiation field.

Temporal analysis of the October 1989 proton flare using computerized anatomical models

NASA Technical Reports Server (NTRS)

Simonsen, L. C.; Cucinotta, F. A.; Atwell, W.; Nealy, J. E.

1993-01-01

The GOES-7 time history data of hourly averaged integral proton fluxes at various particle kinetic energies are analyzed for the solar proton event that occurred between October 19 and 29, 1989. By analyzing the time history data, the dose rates which may vary over many orders of magnitude in the early phases of the flare can be estimated as well as the cumulative dose as a function of time. Basic transport calculations are coupled with detailed body organ thickness distributions from computerized anatomical models to estimate dose rates and cumulative doses to 20 critical body organs. For a 5-cm-thick water shield, cumulative skin, eye, and blood-forming-organ dose equivalents of 1.27, 1.23, and 0.41 Sv, respectively, are estimated. These results are approximately 40-50 percent less than the widely used 0- and 5-cm slab dose estimates. The risk of cancer incidence and mortality are also estimated for astronauts protected by various water shield thicknesses.

Radiation dose optimization in the decommissioning plan for Loviisa NPP

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

Holmberg, R.; Eurajoki, T.

1995-03-01

Finnish rules for nuclear power require a detailed decommissioning plan to be made and kept up to date already during plant operation. The main reasons for this {open_quotes}premature{close_quotes} plan, is, firstly, the need to demonstrate the feasibility of decommissioning, and, secondly, to make realistic cost estimates in order to fund money for this future operation. The decomissioning for Lovissa Nuclear Power Plant (NPP) (2{times}445 MW, PWR) was issued in 1987. It must be updated about every five years. One important aspect of the plant is an estimate of radiation doses to the decomissioning workers. The doses were recently re-estimated becausemore » of a need to decrease the total collective dose estimate in the original plan, 23 manSv. In the update, the dose was reduced by one-third. Part of the reduction was due to changes in the protection and procedures, in which ALARA considerations were taken into account, and partly because of re-estimation of the doses.« less

Shared Dosimetry Error in Epidemiological Dose-Response Analyses

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

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail

2015-03-23

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of "possible" dose history to workers given dose determinants. This paper takesmore » up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. Use of these methods for several studies, including the Mayak Worker Cohort and the U.S. Atomic Veterans Study, is discussed.« less

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.

Radiation response of industrial materials: Dose-rate and morphology implications

NASA Astrophysics Data System (ADS)

Berejka, Anthony J.

2007-08-01

Industrial uses of ionizing radiation mostly rely upon high current, high dose-rate (100 kGy/s) electron beam (EB) accelerators. To a lesser extent, industry uses low dose-rate (2.8 × 10-3 kGy/s) radioactive Cobalt-60 as a gamma source, generally for some rather specific purposes, as medical device sterilization and the treatment of food and foodstuffs. There are nearly nine times as many (∼1400) high current EB units in commercial operation than gamma sources (∼160). However, gamma sources can be easily scaled-down so that much research on materials effects is conducted using gamma radiation. Likewise, laboratories are more likely to have very low beam current and consequently low dose-rate accelerators such as Van de Graaff generators and linear accelerators. With the advent of very high current EB accelerators, X-ray processing has become an industrially viable option. With X-rays from high power sources, dose-rates can be modulated based upon accelerator power and the attenuation of the X-ray by the distance of the material from the X-ray target. Dose and dose-rate dependence has been found to be of consequence in several commercial applications which can employ the use of ionizing radiation. The combination of dose and dose-rate dependence of the polymerization and crosslinking of wood impregnants and of fiber composite matrix materials can yield more economically viable results which have promising commercial potential. Monomer and oligomer structure also play an important role in attaining these desirable results. The influence of morphology is shown on the radiation response of olefin polymers, such as ethylene, propylene and isobutylene polymers and their copolymers. Both controlled morphology and controlled dose-rate have commercial consequences. These are also impacted both by the adroit selection of materials and through the possible use of X-ray processing.

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

A tiered asthma hazard characterization and exposure assessment approach for evaluation of consumer product ingredients.

PubMed

Maier, Andrew; Vincent, Melissa J; Parker, Ann; Gadagbui, Bernard K; Jayjock, Michael

2015-12-01

Asthma is a complex syndrome with significant consequences for those affected. The number of individuals affected is growing, although the reasons for the increase are uncertain. Ensuring the effective management of potential exposures follows from substantial evidence that exposure to some chemicals can increase the likelihood of asthma responses. We have developed a safety assessment approach tailored to the screening of asthma risks from residential consumer product ingredients as a proactive risk management tool. Several key features of the proposed approach advance the assessment resources often used for asthma issues. First, a quantitative health benchmark for asthma or related endpoints (irritation and sensitization) is provided that extends qualitative hazard classification methods. Second, a parallel structure is employed to include dose-response methods for asthma endpoints and methods for scenario specific exposure estimation. The two parallel tracks are integrated in a risk characterization step. Third, a tiered assessment structure is provided to accommodate different amounts of data for both the dose-response assessment (i.e., use of existing benchmarks, hazard banding, or the threshold of toxicological concern) and exposure estimation (i.e., use of empirical data, model estimates, or exposure categories). Tools building from traditional methods and resources have been adapted to address specific issues pertinent to asthma toxicology (e.g., mode-of-action and dose-response features) and the nature of residential consumer product use scenarios (e.g., product use patterns and exposure durations). A case study for acetic acid as used in various sentinel products and residential cleaning scenarios was developed to test the safety assessment methodology. In particular, the results were used to refine and verify relationships among tiered approaches such that each lower data tier in the approach provides a similar or greater margin of safety for a given scenario. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Experimental determination of particle range and dose distribution in thick targets through fragmentation reactions of stable heavy ions.

PubMed

Inaniwa, Taku; Kohno, Toshiyuki; Tomitani, Takehiro; Urakabe, Eriko; Sato, Shinji; Kanazawa, Mitsutaka; Kanai, Tatsuaki

2006-09-07

In radiation therapy with highly energetic heavy ions, the conformal irradiation of a tumour can be achieved by using their advantageous features such as the good dose localization and the high relative biological effectiveness around their mean range. For effective utilization of such properties, it is necessary to evaluate the range of incident ions and the deposited dose distribution in a patient's body. Several methods have been proposed to derive such physical quantities; one of them uses positron emitters generated through projectile fragmentation reactions of incident ions with target nuclei. We have proposed the application of the maximum likelihood estimation (MLE) method to a detected annihilation gamma-ray distribution for determination of the range of incident ions in a target and we have demonstrated the effectiveness of the method with computer simulations. In this paper, a water, a polyethylene and a polymethyl methacrylate target were each irradiated with stable (12)C, (14)N, (16)O and (20)Ne beams. Except for a few combinations of incident beams and targets, the MLE method could determine the range of incident ions R(MLE) with a difference between R(MLE) and the experimental range of less than 2.0 mm under the circumstance that the measurement of annihilation gamma rays was started just after the irradiation of 61.4 s and lasted for 500 s. In the process of evaluating the range of incident ions with the MLE method, we must calculate many physical quantities such as the fluence and the energy of both primary ions and fragments as a function of depth in a target. Consequently, by using them we can obtain the dose distribution. Thus, when the mean range of incident ions is determined with the MLE method, the annihilation gamma-ray distribution and the deposited dose distribution can be derived simultaneously. The derived dose distributions in water for the mono-energetic heavy-ion beams of four species were compared with those measured with an ionization chamber. The good agreement between the derived and the measured distributions implies that the deposited dose distribution in a target can be estimated from the detected annihilation gamma-ray distribution with a positron camera.

Effective dose estimation for pediatric upper gastrointestinal examinations using an anthropomorphic phantom set and metal oxide semiconductor field-effect transistor (MOSFET) technology.

PubMed

Emigh, Brent; Gordon, Christopher L; Connolly, Bairbre L; Falkiner, Michelle; Thomas, Karen E

2013-09-01

There is a need for updated radiation dose estimates in pediatric fluoroscopy given the routine use of new dose-saving technologies and increased radiation safety awareness in pediatric imaging. To estimate effective doses for standardized pediatric upper gastrointestinal (UGI) examinations at our institute using direct dose measurement, as well as provide dose-area product (DAP) to effective dose conversion factors to be used for the estimation of UGI effective doses for boys and girls up to 10 years of age at other centers. Metal oxide semiconductor field-effect transistor (MOSFET) dosimeters were placed within four anthropomorphic phantoms representing children ≤10 years of age and exposed to mock UGI examinations using exposures much greater than used clinically to minimize measurement error. Measured effective dose was calculated using ICRP 103 weights and scaled to our institution's standardized clinical UGI (3.6-min fluoroscopy, four spot exposures and four examination beam projections) as determined from patient logs. Results were compared to Monte Carlo simulations and related to fluoroscope-displayed DAP. Measured effective doses for standardized pediatric UGI examinations in our institute ranged from 0.35 to 0.79 mSv in girls and were 3-8% lower for boys. Simulation-derived and measured effective doses were in agreement (percentage differences <19%, T > 0.18). DAP-to-effective dose conversion factors ranged from 6.5 ×10(-4) mSv per Gy-cm(2) to 4.3 × 10(-3) mSv per Gy-cm(2) for girls and were similarly lower for boys. Using modern fluoroscopy equipment, the effective dose associated with the UGI examination in children ≤10 years at our institute is < 1 mSv. Estimations of effective dose associated with pediatric UGI examinations can be made for children up to the age of 10 using the DAP-normalized conversion factors provided in this study. These estimates can be further refined to reflect individual hospital examination protocols through the use of direct organ dose measurement using MOSFETs, which were shown to agree with Monte Carlo simulated doses.

Radiation Exposure and Attributable Cancer Risk in Patients With Esophageal Atresia.

PubMed

Yousef, Yasmine; Baird, Robert

2018-02-01

Cases of esophageal carcinoma have been documented in survivors of esophageal atresia (EA). Children with EA undergo considerable amounts of diagnostic imaging and consequent radiation exposure potentially increasing their lifetime cancer mortality risk. This study evaluates the radiological procedures performed on patients with EA and estimates their cumulative radiation exposure and attributable lifetime cancer mortality risk. Medical records of patients with EA managed at a tertiary care center were reviewed for demographics, EA subtype, and number and type of radiological investigations. Existing normative data were used to estimate the cumulative radiation exposure and lifetime cancer risk per patient. The present study included 53 patients with a mean follow-up of 5.7 years. The overall median and maximum estimated effective radiation dose in the neonatal period was 5521.4 μSv/patient and 66638.6 μSv/patient, respectively. This correlates to a median and maximum estimated cumulative lifetime cancer mortality risk of 1:1530 and 1:130, respectively. Hence, radiation exposure in the neonatal period increased the cumulative cancer mortality risk a median of 130-fold and a maximum of 1575-fold in EA survivors. Children with EA are exposed to significant amounts of radiation and an increased estimated cumulative cancer mortality risk. Efforts should be made to eliminate superfluous imaging.

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.

Uncertainty of fast biological radiation dose assessment for emergency response scenarios.

PubMed

Ainsbury, Elizabeth A; Higueras, Manuel; Puig, Pedro; Einbeck, Jochen; Samaga, Daniel; Barquinero, Joan Francesc; Barrios, Lleonard; Brzozowska, Beata; Fattibene, Paola; Gregoire, Eric; Jaworska, Alicja; Lloyd, David; Oestreicher, Ursula; Romm, Horst; Rothkamm, Kai; Roy, Laurence; Sommer, Sylwester; Terzoudi, Georgia; Thierens, Hubert; Trompier, Francois; Vral, Anne; Woda, Clemens

2017-01-01

Reliable dose estimation is an important factor in appropriate dosimetric triage categorization of exposed individuals to support radiation emergency response. Following work done under the EU FP7 MULTIBIODOSE and RENEB projects, formal methods for defining uncertainties on biological dose estimates are compared using simulated and real data from recent exercises. The results demonstrate that a Bayesian method of uncertainty assessment is the most appropriate, even in the absence of detailed prior information. The relative accuracy and relevance of techniques for calculating uncertainty and combining assay results to produce single dose and uncertainty estimates is further discussed. Finally, it is demonstrated that whatever uncertainty estimation method is employed, ignoring the uncertainty on fast dose assessments can have an important impact on rapid biodosimetric categorization.

Chernobyl accident: reconstruction of thyroid dose for inhabitants of the Republic of Belarus.

PubMed

Gavrilin, Y I; Khrouch, V T; Shinkarev, S M; Krysenko, N A; Skryabin, A M; Bouville, A; Anspaugh, L R

1999-02-01

The Chernobyl accident in April 1986 resulted in widespread contamination of the environment with radioactive materials, including (131)I and other radioiodines. This environmental contamination led to substantial radiation doses in the thyroids of many inhabitants of the Republic of Belarus. The reconstruction of thyroid doses received by Belarussians is based primarily on exposure rates measured against the neck of more than 200,000 people in the more contaminated territories; these measurements were carried out within a few weeks after the accident and before the decay of (131)I to negligible levels. Preliminary estimates of thyroid dose have been divided into 3 classes: Class 1 ("measured" doses), Class 2 (doses "derived by affinity"), and Class 3 ("empirically-derived" doses). Class 1 doses are estimated directly from the measured thyroidal (131)I content of the person considered, plus information on lifestyle and dietary habits. Such estimates are available for about 130,000 individuals from the contaminated areas of the Gomel and Mogilev Oblasts and from the city of Minsk. Maximum individual doses are estimated to range up to about 60 Gy. For every village with a sufficient number of residents with Class 1 doses, individual thyroid dose distributions are determined for several age groups and levels of milk consumption. These data are used to derive Class 2 thyroid dose estimates for unmeasured inhabitants of these villages. For any village where the number of residents with Class 1 thyroid doses is small or equal to zero, individual thyroid doses of Class 3 are derived from the relationship obtained between the mean adult thyroid dose and the deposition density of (131)I or 137Cs in villages with Class 2 thyroid doses presenting characteristics similar to those of the village considered. In order to improve the reliability of the Class 3 thyroid doses, an extensive program of measurement of (129)I in soils is envisaged.

Plasma induced DNA damage: Comparison with the effects of ionizing radiation

NASA Astrophysics Data System (ADS)

Lazović, S.; Maletić, D.; Leskovac, A.; Filipović, J.; Puač, N.; Malović, G.; Joksić, G.; Petrović, Z. Lj.

2014-09-01

We use human primary fibroblasts for comparing plasma and gamma rays induced DNA damage. In both cases, DNA strand breaks occur, but of fundamentally different nature. Unlike gamma exposure, contact with plasma predominantly leads to single strand breaks and base-damages, while double strand breaks are mainly consequence of the cell repair mechanisms. Different cell signaling mechanisms are detected confirming this (ataxia telangiectasia mutated - ATM and ataxia telangiectasia and Rad3 related - ATR, respectively). The effective plasma doses can be tuned to match the typical therapeutic doses of 2 Gy. Tailoring the effective dose through plasma power and duration of the treatment enables safety precautions mainly by inducing apoptosis and consequently reduced frequency of micronuclei.

SU-E-J-14: A Novel Approach to Evaluate the Dosimetric Effect of Rectal Variation During Image Guided Prostate Radiotherapy

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

Murray, J; McQuaid, D; Dunlop, A

2014-06-01

Purpose: Deformable registration establishes the spatial correspondence back to the reference image in order to accumulate dose. However, in prostate radiotherapy the changing shape and volume of the rectum present a challenge to accurate deformable registration and consequently calculation of delivered dose. We explored an alternative approach to calculating accumulated dose to the rectum, independent of deformable registration. Methods: This study was performed on three patients who received online image-guided radiotherapy (IGRT) with daily CBCT (XVI-system,Elekta) and target localization using intraprostatic fiducials. On each CBCT, the rectum was manually contoured and bulk density assignments were made allowing dose to bemore » calculated for each fraction. Dose-surface maps (DSM) were generated (MATLAB,Mathworks,Natick,MA) by considering the rectum as a cylinder and sampling the dose at 21-equispaced points on each CT slice. The cylinder was “cut” at the posterior-most position on each CT and unfolded to generate a DSM. These were normalised in the longitudinal direction by interpolation creating maps of 21×21 pixels. A DSM was produced for each CBCT and the dose was accumulated. Results: The mean accumulated delivered rectal surface dose was on average 7.5(+/−3.5)% lower than the planned dose. The dose difference maps consistently show that the greatest variation in dose between planned and delivered dose is away from where the rectal surface is adjacent to the prostate. Conclusion: Estimation of dose accumulation using DSM provides an alternative method for determining actual delivered dose to the rectum. The dose difference is greatest in areas away from the region where the rectal surface abuts the prostate, the region where set-up is verified. The change in size and shape of the rectum was shown to resultin a change in the accumulated dose compared to the planned dose and this will have an impact on determining the relationships between dose delivered and toxicity. We acknowledge funding from CRUK and acknowledge NHS funding to the NIHR Biomedical Research Centre for Cancer. Patients were treated within the CHHiP IGRT sub-study (CRUK/06/016, ISRCTN:97182923) funded by CRUK. RayStation was used under an evaluation agreement with RaySearch Laboratories AB.« less

Impact of the Revised 10 CFR 835 on the Neutron Dose Rates at LLNL

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

Radev, R

2009-01-13

In June 2007, 10 CFR 835 [1] was revised to include new radiation weighting factors for neutrons, updated dosimetric models, and dose terms consistent with the newer ICRP recommendations. A significant aspect of the revised 10 CFR 835 is the adoption of the recommendations outlined in ICRP-60 [2]. The recommended new quantities demand a review of much of the basic data used in protection against exposure to sources of ionizing radiation. The International Commission on Radiation Units and Measurements has defined a number of quantities for use in personnel and area monitoring [3,4,5] including the ambient dose equivalent H*(d) tomore » be used for area monitoring and instrument calibrations. These quantities are used in ICRP-60 and ICRP-74. This report deals only with the changes in the ambient dose equivalent and ambient dose rate equivalent for neutrons as a result of the implementation of the revised 10 CFR 835. In the report, the terms neutron dose and neutron dose rate will be used for convenience for ambient neutron dose and ambient neutron dose rate unless otherwise stated. This report provides a qualitative and quantitative estimate of how much the neutron dose rates at LLNL will change with the implementation of the revised 10 CFR 835. Neutron spectra and dose rates from selected locations at the LLNL were measured with a high resolution spectroscopic neutron dose rate system (ROSPEC) as well as with a standard neutron rem meter (a.k.a., a remball). The spectra obtained at these locations compare well with the spectra from the Radiation Calibration Laboratory's (RCL) bare californium source that is currently used to calibrate neutron dose rate instruments. The measurements obtained from the high resolution neutron spectrometer and dose meter ROSPEC and the NRD dose meter compare within the range of {+-}25%. When the new radiation weighting factors are adopted with the implementation of the revised 10 CFR 835, the measured dose rates will increase by up to 22%. The health physicists should consider this increase for any areas that have dose rates near a posting limit, such as near the 100 mrem/hr for a high radiation area, as this increase in measured dose rate may result in some changes to postings and consequent radiological controls.« less

Peak skin and eye lens radiation dose from brain perfusion CT based on Monte Carlo simulation.

PubMed

Zhang, Di; Cagnon, Chris H; Villablanca, J Pablo; McCollough, Cynthia H; Cody, Dianna D; Stevens, Donna M; Zankl, Maria; Demarco, John J; Turner, Adam C; Khatonabadi, Maryam; McNitt-Gray, Michael F

2012-02-01

The purpose of our study was to accurately estimate the radiation dose to skin and the eye lens from clinical CT brain perfusion studies, investigate how well scanner output (expressed as volume CT dose index [CTDI(vol)]) matches these estimated doses, and investigate the efficacy of eye lens dose reduction techniques. Peak skin dose and eye lens dose were estimated using Monte Carlo simulation methods on a voxelized patient model and 64-MDCT scanners from four major manufacturers. A range of clinical protocols was evaluated. CTDI(vol) for each scanner was obtained from the scanner console. Dose reduction to the eye lens was evaluated for various gantry tilt angles as well as scan locations. Peak skin dose and eye lens dose ranged from 81 mGy to 348 mGy, depending on the scanner and protocol used. Peak skin dose and eye lens dose were observed to be 66-79% and 59-63%, respectively, of the CTDI(vol) values reported by the scanners. The eye lens dose was significantly reduced when the eye lenses were not directly irradiated. CTDI(vol) should not be interpreted as patient dose; this study has shown it to overestimate dose to the skin or eye lens. These results may be used to provide more accurate estimates of actual dose to ensure that protocols are operated safely below thresholds. Tilting the gantry or moving the scanning region further away from the eyes are effective for reducing lens dose in clinical practice. These actions should be considered when they are consistent with the clinical task and patient anatomy.

DOSE COEFFICIENTS FOR LIVER CHEMOEMBOLISATION PROCEDURES USING MONTE CARLO CODE.

PubMed

Karavasilis, E; Dimitriadis, A; Gonis, H; Pappas, P; Georgiou, E; Yakoumakis, E

2016-12-01

The aim of the present study is the estimation of radiation burden during liver chemoembolisation procedures. Organ dose and effective dose conversion factors, normalised to dose-area product (DAP), were estimated for chemoembolisation procedures using a Monte Carlo transport code in conjunction with an adult mathematical phantom. Exposure data from 32 patients were used to determine the exposure projections for the simulations. Equivalent organ (H T ) and effective (E) doses were estimated using individual DAP values. The organs receiving the highest amount of doses during these exams were lumbar spine, liver and kidneys. The mean effective dose conversion factor was 1.4 Sv Gy -1 m -2 Dose conversion factors can be useful for patient-specific radiation burden during chemoembolisation procedures. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A database for estimating organ dose for coronary angiography and brain perfusion CT scans for arbitrary spectra and angular tube current modulation

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

Rupcich, Franco; Badal, Andreu; Kyprianou, Iacovos

Purpose: The purpose of this study was to develop a database for estimating organ dose in a voxelized patient model for coronary angiography and brain perfusion CT acquisitions with any spectra and angular tube current modulation setting. The database enables organ dose estimation for existing and novel acquisition techniques without requiring Monte Carlo simulations. Methods: The study simulated transport of monoenergetic photons between 5 and 150 keV for 1000 projections over 360 Degree-Sign through anthropomorphic voxelized female chest and head (0 Degree-Sign and 30 Degree-Sign tilt) phantoms and standard head and body CTDI dosimetry cylinders. The simulations resulted in tablesmore » of normalized dose deposition for several radiosensitive organs quantifying the organ dose per emitted photon for each incident photon energy and projection angle for coronary angiography and brain perfusion acquisitions. The values in a table can be multiplied by an incident spectrum and number of photons at each projection angle and then summed across all energies and angles to estimate total organ dose. Scanner-specific organ dose may be approximated by normalizing the database-estimated organ dose by the database-estimated CTDI{sub vol} and multiplying by a physical CTDI{sub vol} measurement. Two examples are provided demonstrating how to use the tables to estimate relative organ dose. In the first, the change in breast and lung dose during coronary angiography CT scans is calculated for reduced kVp, angular tube current modulation, and partial angle scanning protocols relative to a reference protocol. In the second example, the change in dose to the eye lens is calculated for a brain perfusion CT acquisition in which the gantry is tilted 30 Degree-Sign relative to a nontilted scan. Results: Our database provides tables of normalized dose deposition for several radiosensitive organs irradiated during coronary angiography and brain perfusion CT scans. Validation results indicate total organ doses calculated using our database are within 1% of those calculated using Monte Carlo simulations with the same geometry and scan parameters for all organs except red bone marrow (within 6%), and within 23% of published estimates for different voxelized phantoms. Results from the example of using the database to estimate organ dose for coronary angiography CT acquisitions show 2.1%, 1.1%, and -32% change in breast dose and 2.1%, -0.74%, and 4.7% change in lung dose for reduced kVp, tube current modulated, and partial angle protocols, respectively, relative to the reference protocol. Results show -19.2% difference in dose to eye lens for a tilted scan relative to a nontilted scan. The reported relative changes in organ doses are presented without quantification of image quality and are for the sole purpose of demonstrating the use of the proposed database. Conclusions: The proposed database and calculation method enable the estimation of organ dose for coronary angiography and brain perfusion CT scans utilizing any spectral shape and angular tube current modulation scheme by taking advantage of the precalculated Monte Carlo simulation results. The database can be used in conjunction with image quality studies to develop optimized acquisition techniques and may be particularly beneficial for optimizing dual kVp acquisitions for which numerous kV, mA, and filtration combinations may be investigated.« less

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.

Testing equality and interval estimation in binary responses when high dose cannot be used first under a three-period crossover design.

PubMed

Lui, Kung-Jong; Chang, Kuang-Chao

2015-01-01

When comparing two doses of a new drug with a placebo, we may consider using a crossover design subject to the condition that the high dose cannot be administered before the low dose. Under a random-effects logistic regression model, we focus our attention on dichotomous responses when the high dose cannot be used first under a three-period crossover trial. We derive asymptotic test procedures for testing equality between treatments. We further derive interval estimators to assess the magnitude of the relative treatment effects. We employ Monte Carlo simulation to evaluate the performance of these test procedures and interval estimators in a variety of situations. We use the data taken as a part of trial comparing two different doses of an analgesic with a placebo for the relief of primary dysmenorrhea to illustrate the use of the proposed test procedures and estimators.

Global trends in antimicrobial use in food animals

PubMed Central

Van Boeckel, Thomas P.; Brower, Charles; Gilbert, Marius; Grenfell, Bryan T.; Levin, Simon A.; Robinson, Timothy P.; Teillant, Aude; Laxminarayan, Ramanan

2015-01-01

Demand for animal protein for human consumption is rising globally at an unprecedented rate. Modern animal production practices are associated with regular use of antimicrobials, potentially increasing selection pressure on bacteria to become resistant. Despite the significant potential consequences for antimicrobial resistance, there has been no quantitative measurement of global antimicrobial consumption by livestock. We address this gap by using Bayesian statistical models combining maps of livestock densities, economic projections of demand for meat products, and current estimates of antimicrobial consumption in high-income countries to map antimicrobial use in food animals for 2010 and 2030. We estimate that the global average annual consumption of antimicrobials per kilogram of animal produced was 45 mg⋅kg−1, 148 mg⋅kg−1, and 172 mg⋅kg−1 for cattle, chicken, and pigs, respectively. Starting from this baseline, we estimate that between 2010 and 2030, the global consumption of antimicrobials will increase by 67%, from 63,151 ± 1,560 tons to 105,596 ± 3,605 tons. Up to a third of the increase in consumption in livestock between 2010 and 2030 is imputable to shifting production practices in middle-income countries where extensive farming systems will be replaced by large-scale intensive farming operations that routinely use antimicrobials in subtherapeutic doses. For Brazil, Russia, India, China, and South Africa, the increase in antimicrobial consumption will be 99%, up to seven times the projected population growth in this group of countries. Better understanding of the consequences of the uninhibited growth in veterinary antimicrobial consumption is needed to assess its potential effects on animal and human health. PMID:25792457

Global trends in antimicrobial use in food animals.

PubMed

Van Boeckel, Thomas P; Brower, Charles; Gilbert, Marius; Grenfell, Bryan T; Levin, Simon A; Robinson, Timothy P; Teillant, Aude; Laxminarayan, Ramanan

2015-05-05

Demand for animal protein for human consumption is rising globally at an unprecedented rate. Modern animal production practices are associated with regular use of antimicrobials, potentially increasing selection pressure on bacteria to become resistant. Despite the significant potential consequences for antimicrobial resistance, there has been no quantitative measurement of global antimicrobial consumption by livestock. We address this gap by using Bayesian statistical models combining maps of livestock densities, economic projections of demand for meat products, and current estimates of antimicrobial consumption in high-income countries to map antimicrobial use in food animals for 2010 and 2030. We estimate that the global average annual consumption of antimicrobials per kilogram of animal produced was 45 mg⋅kg(-1), 148 mg⋅kg(-1), and 172 mg⋅kg(-1) for cattle, chicken, and pigs, respectively. Starting from this baseline, we estimate that between 2010 and 2030, the global consumption of antimicrobials will increase by 67%, from 63,151 ± 1,560 tons to 105,596 ± 3,605 tons. Up to a third of the increase in consumption in livestock between 2010 and 2030 is imputable to shifting production practices in middle-income countries where extensive farming systems will be replaced by large-scale intensive farming operations that routinely use antimicrobials in subtherapeutic doses. For Brazil, Russia, India, China, and South Africa, the increase in antimicrobial consumption will be 99%, up to seven times the projected population growth in this group of countries. Better understanding of the consequences of the uninhibited growth in veterinary antimicrobial consumption is needed to assess its potential effects on animal and human health.

DOSESCREEN: a computer program to aid dose placement

Treesearch

Kimberly C. Smith; Jacqueline L. Robertson

1984-01-01

Careful selection of an experimental design for a bioassay substantially improves the precision of effective dose (ED) estimates. Design considerations typically include determination of sample size, dose selection, and allocation of subjects to doses. DOSESCREEN is a computer program written to help investigators select an efficient design for the estimation of an...

Assessment of radiation doses from residential smoke detectors that contain americium-241

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

O'Donnell, F.R.; Etnier, E.L.; Holton, G.A.

1981-10-01

External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq (3 ..mu..Ci) americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv (0.4 prem) to 20 nSv (2 ..mu..rem) for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 ..mu..Svmore » (0.0006 to 8 mrem) to total body and from 0.06 to 800 ..mu..Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft/sup 2/).« less

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.

ESR dosimetry for atomic bomb survivors and radiologic technologists

NASA Astrophysics Data System (ADS)

Tatsumi-Miyajima, Junko

1987-06-01

An individual absorbed dose for atomic bomb (A-bomb) survivors and radiologic technologists has been estimated using a new personal dosimetry. This dosimetry is based on the electron spin resonance (ESR) spectroscopy of the CO 33- radicals, which are produced in their teeth by radiation. Measurements were carried out to study the characteristics of the dosimetry; the ESR signals of the CO 33- radicals were stable and increased linearly with the radiation dose. In the evaluation of the absorbed dose, the ESR signals were considered to be a function of photon energy. The absorbed doses in ten cases of A-bomb victims and eight cases of radiologic technologists were determined. For A-bomb survivors, the adsorbed doses, which were estimated using the ESR dosimetry, were consistent with the ones obtained using the calculations of the tissue dose in air of A-bomb, and also with the ones obtained using the chromosome measurements. For radiologic technologists, the absorbed doses, which were estimated using the ESR dosimetry, agreed with the ones calculated using the information on the occupational history and conditions. The advantages of this method are that the absorbed dose can be directly estimated by measuring the ESR signals obtained from the teeth of persons, who are exposed to radiation. Therefore, the ESR dosimetry is useful to estimate the accidental exposure and the long term cumulative dose.

Statistical strategies for averaging EC50 from multiple dose-response experiments.

PubMed

Jiang, Xiaoqi; Kopp-Schneider, Annette

2015-11-01

In most dose-response studies, repeated experiments are conducted to determine the EC50 value for a chemical, requiring averaging EC50 estimates from a series of experiments. Two statistical strategies, the mixed-effect modeling and the meta-analysis approach, can be applied to estimate average behavior of EC50 values over all experiments by considering the variabilities within and among experiments. We investigated these two strategies in two common cases of multiple dose-response experiments in (a) complete and explicit dose-response relationships are observed in all experiments and in (b) only in a subset of experiments. In case (a), the meta-analysis strategy is a simple and robust method to average EC50 estimates. In case (b), all experimental data sets can be first screened using the dose-response screening plot, which allows visualization and comparison of multiple dose-response experimental results. As long as more than three experiments provide information about complete dose-response relationships, the experiments that cover incomplete relationships can be excluded from the meta-analysis strategy of averaging EC50 estimates. If there are only two experiments containing complete dose-response information, the mixed-effects model approach is suggested. We subsequently provided a web application for non-statisticians to implement the proposed meta-analysis strategy of averaging EC50 estimates from multiple dose-response experiments.

Comparison of Individual Radiosensitivity to γ-Rays and Carbon Ions.

PubMed

Shim, Grace; Normil, Marie Delna; Testard, Isabelle; Hempel, William M; Ricoul, Michelle; Sabatier, Laure

2016-01-01

Carbon ions are an up-and-coming ion species, currently being used in charged particle radiotherapy. As it is well established that there are considerable interindividual differences in radiosensitivity in the general population that can significantly influence clinical outcomes of radiotherapy, we evaluate the degree of these differences in the context of carbon ion therapy compared with conventional radiotherapy. In this study, we evaluate individual radiosensitivity following exposure to carbon-13 ions or γ-rays in peripheral blood lymphocytes of healthy individuals based on the frequency of ionizing radiation (IR)-induced DNA double strand breaks (DSBs) that was either misrepaired or left unrepaired to form chromosomal aberrations (CAs) (simply referred to here as DSBs for brevity). Levels of DSBs were estimated from the scoring of CAs visualized with telomere/centromere-fluorescence in situ hybridization (TC-FISH). We examine radiosensitivity at the dose of 2 Gy, a routinely administered dose during fractionated radiotherapy, and we determined that a wide range of DSBs were induced by the given dose among healthy individuals, with highly radiosensitive individuals harboring more IR-induced breaks in the genome than radioresistant individuals following exposure to the same dose. Furthermore, we determined the relative effectiveness of carbon irradiation in comparison to γ-irradiation in the induction of DSBs at each studied dose (isodose effect), a quality we term "relative dose effect" (RDE). This ratio is advantageous, as it allows for simple comparison of dose-response curves. At 2 Gy, carbon irradiation was three times more effective in inducing DSBs compared with γ-irradiation (RDE of 3); these results were confirmed using a second cytogenetic technique, multicolor-FISH. We also analyze radiosensitivity at other doses (0.2-15 Gy), to represent hypo- and hyperfractionation doses and determined that RDE is dose dependent: high ratios at low doses, and approaching 1 at high doses. These results could have clinical implications as IR-induced DNA damage and the ensuing CAs and genomic instability can have significant cellular consequences that could potentially have profound implications for long-term human health after IR exposure, such as the emergence of secondary cancers and other pathobiological conditions after radiotherapy.

Biodosimetry estimate for high-LET irradiation.

PubMed

Wang, Z Z; Li, W J; Zhi, D J; Jing, X G; Wei, W; Gao, Q X; Liu, B

2007-08-01

The purpose of this paper is to prepare for an easy and reliable biodosimeter protocol for radiation accidents involving high-linear energy transfer (LET) exposure. Human peripheral blood lymphocytes were irradiated using carbon ions (LET: 34.6 keV microm(-1)), and the chromosome aberrations induced were analyzed using both a conventional colcemid block method and a calyculin A induced premature chromosome condensation (PCC) method. At a lower dose range (0-4 Gy), the measured dicentric (dics) and centric ring chromosomes (cRings) provided reasonable dose information. At higher doses (8 Gy), however, the frequency of dics and cRings was not suitable for dose estimation. Instead, we found that the number of Giemsa-stained drug-induced G2 prematurely condensed chromosomes (G2-PCC) can be used for dose estimation, since the total chromosome number (including fragments) was linearly correlated with radiation dose (r = 0.99). The ratio of the longest and the shortest chromosome length of the drug-induced G2-PCCs increased with radiation dose in a linear-quadratic manner (r = 0.96), which indicates that this ratio can also be used to estimate radiation doses. Obviously, it is easier to establish the dose response curve using the PCC technique than using the conventional metaphase chromosome method. It is assumed that combining the ratio of the longest and the shortest chromosome length with analysis of the total chromosome number might be a valuable tool for rapid and precise dose estimation for victims of radiation accidents.

Estimation of thyroid radiation doses for the hanford thyroid disease study: results and implications for statistical power of the epidemiological analyses.

PubMed

Kopecky, Kenneth J; Davis, Scott; Hamilton, Thomas E; Saporito, Mark S; Onstad, Lynn E

2004-07-01

Residents of eastern Washington, northeastern Oregon, and western Idaho were exposed to I released into the atmosphere from operations at the Hanford Nuclear Site from 1944 through 1972, especially in the late 1940's and early 1950's. This paper describes the estimated doses to the thyroid glands of the 3,440 evaluable participants in the Hanford Thyroid Disease Study, which investigated whether thyroid morbidity was increased in people exposed to radioactive iodine from Hanford during 1944-1957. The participants were born during 1940-1946 to mothers living in Benton, Franklin, Walla Walla, Adams, Okanogan, Ferry, or Stevens Counties in Washington State. Whenever possible someone with direct knowledge of the participant's early life (preferably the participant's mother) was interviewed about the participant's individual dose-determining characteristics (residence history, sources and quantities of food, milk, and milk products consumed, production and processing techniques for home-grown food and milk products). Default information was used if no interview respondent was available. Thyroid doses were estimated using the computer program Calculation of Individual Doses from Environmental Radionuclides (CIDER) developed by the Hanford Environmental Dose Reconstruction Project. CIDER provided 100 sets of doses to represent uncertainty of the estimates. These sets were not generated independently for each participant, but reflected the effects of uncertainties in characteristics shared by participants. Estimated doses (medians of each participant's 100 realizations) ranged from 0.0029 mGy to 2823 mGy, with mean and median of 174 and 97 mGy, respectively. The distribution of estimated doses provided the Hanford Thyroid Disease Study with sufficient statistical power to test for dose-response relationships between thyroid outcomes and exposure to Hanford's I.

Estimating cancer risk from dental cone-beam CT exposures based on skin dosimetry

NASA Astrophysics Data System (ADS)

Pauwels, Ruben; Cockmartin, Lesley; Ivanauskaité, Deimante; Urbonienė, Ausra; Gavala, Sophia; Donta, Catherine; Tsiklakis, Kostas; Jacobs, Reinhilde; Bosmans, Hilde; Bogaerts, Ria; Horner, Keith; SEDENTEXCT Project Consortium, The

2014-07-01

The aim of this study was to measure entrance skin doses on patients undergoing cone-beam computed tomography (CBCT) examinations, to establish conversion factors between skin and organ doses, and to estimate cancer risk from CBCT exposures. 266 patients (age 8-83) were included, involving three imaging centres. CBCT scans were acquired using the SCANORA 3D (Soredex, Tuusula, Finland) and NewTom 9000 (QR, Verona, Italy). Eight thermoluminescent dosimeters were attached to the patient's skin at standardized locations. Using previously published organ dose estimations on various CBCTs with an anthropomorphic phantom, correlation factors to convert skin dose to organ doses were calculated and applied to estimate patient organ doses. The BEIR VII age- and gender-dependent dose-risk model was applied to estimate the lifetime attributable cancer risk. For the SCANORA 3D, average skin doses over the eight locations varied between 484 and 1788 µGy. For the NewTom 9000 the range was between 821 and 1686 µGy for Centre 1 and between 292 and 2325 µGy for Centre 2. Entrance skin dose measurements demonstrated the combined effect of exposure and patient factors on the dose. The lifetime attributable cancer risk, expressed as the probability to develop a radiation-induced cancer, varied between 2.7 per million (age >60) and 9.8 per million (age 8-11) with an average of 6.0 per million. On average, the risk for female patients was 40% higher. The estimated radiation risk was primarily influenced by the age at exposure and the gender, pointing out the continuing need for justification and optimization of CBCT exposures, with a specific focus on children.

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-, partially- and indirectly-irradiated organ dose from TCM CT exams. By accounting for the effects of patient size in the organ dose estimates, a comprehensive set of patient-specific dose estimates from TCM CT exams was developed. These patient-specific organ dose estimates from TCM CT exams will provide a more complete understanding of the dose impact and risks associated with modern body CT scanning protocols.

Analysis of EPR and FISH studies of radiation doses in persons who lived in the upper reaches of the Techa River.

PubMed

Degteva, M O; Shagina, N B; Shishkina, E A; Vozilova, A V; Volchkova, A Y; Vorobiova, M I; Wieser, A; Fattibene, P; Della Monaca, S; Ainsbury, E; Moquet, J; Anspaugh, L R; Napier, B A

2015-11-01

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949-1956 resulted in significant doses to about 30,000 persons who lived in downstream settlements. The residents were exposed to internal and external radiation. Two methods for reconstruction of the external dose are considered in this paper, electron paramagnetic resonance (EPR) measurements of teeth, and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. The main issue in the application of the EPR and FISH methods for reconstruction of the external dose for the Techa Riverside residents was strontium radioisotopes incorporated in teeth and bones that act as a source of confounding local exposures. In order to estimate and subtract doses from incorporated (89,90)Sr, the EPR and FISH assays were supported by measurements of (90)Sr-body burdens and estimates of (90)Sr concentrations in dental tissues by the luminescence method. The resulting dose estimates derived from EPR to FISH measurements for residents of the upper Techa River were found to be consistent: The mean values vary from 510 to 550 mGy for the villages located close to the site of radioactive release to 130-160 mGy for the more distant villages. The upper bound of individual estimates for both methods is equal to 2.2-2.3 Gy. The EPR- and FISH-based dose estimates were compared with the doses calculated for the donors using the most recent Techa River Dosimetry System (TRDS). The TRDS external dose assessments are based on the data on contamination of the Techa River floodplain, simulation of air kerma above the contaminated soil, age-dependent lifestyles and individual residence histories. For correct comparison, TRDS-based doses were calculated from two sources: external exposure from the contaminated environment and internal exposure from (137)Cs incorporated in donors' soft tissues. It is shown here that the TRDS-based absorbed doses in tooth enamel and muscle are in agreement with EPR- and FISH-based estimates within uncertainty bounds. Basically, this agreement between the estimates has confirmed the validity of external doses calculated with the TRDS.

Electron spin resonance analysis of tooth enamel does not indicate exposures to large radiation doses in a large proportion of distally-exposed A-bomb survivors.

PubMed

Hirai, Yuko; Kodama, Yoshiaki; Cullings, Harry M; Miyazawa, Chuzo; Nakamura, Nori

2011-01-01

The atomic bombs in Hiroshima and Nagasaki led to two different types of radiation exposure; one was direct and brief and the other was indirect and persistent. The latter (so-called exposure to residual radiation) resulted from the presence of neutron activation products in the soil, or from fission products present in the fallout. Compared with the doses from direct exposures, estimations of individual doses from residual radiation have been much more complicated, and estimates vary widely among researchers. The present report bases its conclusions on radiation doses recorded in tooth enamel from survivors in Hiroshima. Those survivors were present at distances of about 3 km or greater from the hypocenter at the time of the explosion, and have DS02 estimated doses (direct exposure doses) of less than 5 mGy (and are regarded as control subjects). Individual doses were estimated by measuring CO(2)(-) radicals in tooth enamel with the electron spin resonance (ESR; or electron paramagnetic resonance, EPR) method. The results from 56 molars donated by 49 survivors provided estimated doses which vary from -200 mGy to 500 mGy, and the median dose was 17 mGy (25% and 75% quartiles are -54 mGy and 137 mGy, respectively) for the buccal parts and 13 mGy (25% and 75% quartiles: -49 mGy and 87 mGy, respectively) for the lingual parts of the molars. Three molars had ESR-estimated doses of 300 to 400 mGy for both the buccal and lingual parts, which indicates possible exposures to excess doses of penetrating radiation, although the origin of such radiation remains to be determined. The results did not support claims that a large fraction of distally-exposed survivors received large doses (e.g. 1 Gy) of external penetrating radiation resulting from residual radiation.

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.

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 across patient populations within a practice. © RSNA, 2013 PMID:24126364

Radiation exposure assessment for portsmouth naval shipyard health studies.

PubMed

Daniels, R D; Taulbee, T D; Chen, P

2004-01-01

Occupational radiation exposures of 13,475 civilian nuclear shipyard workers were investigated as part of a retrospective mortality study. Estimates of annual, cumulative and collective doses were tabulated for future dose-response analysis. Record sets were assembled and amended through range checks, examination of distributions and inspection. Methods were developed to adjust for administrative overestimates and dose from previous employment. Uncertainties from doses below the recording threshold were estimated. Low-dose protracted radiation exposures from submarine overhaul and repair predominated. Cumulative doses are best approximated by a hybrid log-normal distribution with arithmetic mean and median values of 20.59 and 3.24 mSv, respectively. The distribution is highly skewed with more than half the workers having cumulative doses <10 mSv and >95% having doses <100 mSv. The maximum cumulative dose is estimated at 649.39 mSv from 15 person-years of exposure. The collective dose was 277.42 person-Sv with 96.8% attributed to employment at Portsmouth Naval Shipyard.

The Russian radiation legacy: its integrated impact and lessons.

PubMed Central

Goldman, M

1997-01-01

Information about the consequences of human exposure to radiation in the former Soviet Union has recently become available. These data add new insights and provide possible answers to several important questions regarding radiation and its impact on occupational and public health. The 1986 Chernobyl accident initiated a major and early increase in childhood thyroid cancer that resulted from ingestion of iodine-131 (131I) by young children living in the most heavily contaminated areas of Belarus, Ukraine, and Russia. No significant additional cancer or other adverse medical effects have yet been reported in the affected populations and among clean-up workers. Major psychological stress independent of radiation dose has been observed in those people thought to be exposed. During the early days of the atomic energy program in the former Soviet Union, some unfortunate events occurred. The country's first atomic test in Semipalatinsk in 1949 exposed over 25,000 people downwind from the blast to significant doses of fission products, especially 131I. During the late 1940s and the early 1950s nuclear material production facilities were developed near Chelyabinsk in the South Ural Mountains, which resulted in major releases into the environment and significant overexposures for thousands of workers and nearby populations. Chronic radiation sickness was observed early in exposed workers, and increases in leukemia and other cancers were also reported. The series of plutonium inhalation-related lung cancers and fatalities among workers exposed in that first decade appears to be unique. Long-term consequences of chronic radiation sickness and four decades of follow-up are being described for the first time. Villagers downstream from the plant consumed high levels of 137Cs and 90Sr and, it is reported, manifested increases in leukemia from internal and external exposures. Although the 40-year databases for retrospective dosimetry epidemiology studies are just beginning to be integrated and evaluated, preliminary evaluations suggest that there may be graded, significant dose-rate amelioration factors for cancer and leukemia risks in workers and the general population relative to the risk data on the Japanese atomic bomb survivors. Even for plutonium-induced lung cancers in workers, such a dose-rate effect may be evident. These experiences give us insight into the consequences of protracted radiation at high and low doses and rates. If these findings are validated and confirmed, they can provide information that reduces some of the uncertainties in retrospective radiation dosimetry and radiation risk estimates (especially for low-level, chronic exposures) for activities related to medicine as well as the handling of nuclear materials and nuclear facility decommissioning, decontamination, and demilitarization. PMID:9467049

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.

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

The Impact of Acquisition Dose on Quantitative Breast Density Estimation with Digital Mammography: Results from ACRIN PA 4006.

PubMed

Chen, Lin; Ray, Shonket; Keller, Brad M; Pertuz, Said; McDonald, Elizabeth S; Conant, Emily F; Kontos, Despina

2016-09-01

Purpose To investigate the impact of radiation dose on breast density estimation in digital mammography. Materials and Methods With institutional review board approval and Health Insurance Portability and Accountability Act compliance under waiver of consent, a cohort of women from the American College of Radiology Imaging Network Pennsylvania 4006 trial was retrospectively analyzed. All patients underwent breast screening with a combination of dose protocols, including standard full-field digital mammography, low-dose digital mammography, and digital breast tomosynthesis. A total of 5832 images from 486 women were analyzed with previously validated, fully automated software for quantitative estimation of density. Clinical Breast Imaging Reporting and Data System (BI-RADS) density assessment results were also available from the trial reports. The influence of image acquisition radiation dose on quantitative breast density estimation was investigated with analysis of variance and linear regression. Pairwise comparisons of density estimations at different dose levels were performed with Student t test. Agreement of estimation was evaluated with quartile-weighted Cohen kappa values and Bland-Altman limits of agreement. Results Radiation dose of image acquisition did not significantly affect quantitative density measurements (analysis of variance, P = .37 to P = .75), with percent density demonstrating a high overall correlation between protocols (r = 0.88-0.95; weighted κ = 0.83-0.90). However, differences in breast percent density (1.04% and 3.84%, P < .05) were observed within high BI-RADS density categories, although they were significantly correlated across the different acquisition dose levels (r = 0.76-0.92, P < .05). Conclusion Precision and reproducibility of automated breast density measurements with digital mammography are not substantially affected by variations in radiation dose; thus, the use of low-dose techniques for the purpose of density estimation may be feasible. (©) RSNA, 2016 Online supplemental material is available for this article.

The Impact of Acquisition Dose on Quantitative Breast Density Estimation with Digital Mammography: Results from ACRIN PA 4006

PubMed Central

Chen, Lin; Ray, Shonket; Keller, Brad M.; Pertuz, Said; McDonald, Elizabeth S.; Conant, Emily F.

2016-01-01

Purpose To investigate the impact of radiation dose on breast density estimation in digital mammography. Materials and Methods With institutional review board approval and Health Insurance Portability and Accountability Act compliance under waiver of consent, a cohort of women from the American College of Radiology Imaging Network Pennsylvania 4006 trial was retrospectively analyzed. All patients underwent breast screening with a combination of dose protocols, including standard full-field digital mammography, low-dose digital mammography, and digital breast tomosynthesis. A total of 5832 images from 486 women were analyzed with previously validated, fully automated software for quantitative estimation of density. Clinical Breast Imaging Reporting and Data System (BI-RADS) density assessment results were also available from the trial reports. The influence of image acquisition radiation dose on quantitative breast density estimation was investigated with analysis of variance and linear regression. Pairwise comparisons of density estimations at different dose levels were performed with Student t test. Agreement of estimation was evaluated with quartile-weighted Cohen kappa values and Bland-Altman limits of agreement. Results Radiation dose of image acquisition did not significantly affect quantitative density measurements (analysis of variance, P = .37 to P = .75), with percent density demonstrating a high overall correlation between protocols (r = 0.88–0.95; weighted κ = 0.83–0.90). However, differences in breast percent density (1.04% and 3.84%, P < .05) were observed within high BI-RADS density categories, although they were significantly correlated across the different acquisition dose levels (r = 0.76–0.92, P < .05). Conclusion Precision and reproducibility of automated breast density measurements with digital mammography are not substantially affected by variations in radiation dose; thus, the use of low-dose techniques for the purpose of density estimation may be feasible. © RSNA, 2016 Online supplemental material is available for this article. PMID:27002418

Assessment of the point-source method for estimating dose rates to members of the public from exposure to patients with 131I thyroid treatment

DOE PAGES

Dewji, Shaheen Azim; Bellamy, Michael B.; Hertel, Nolan E.; ...

2015-09-01

The U.S. Nuclear Regulatory Commission (USNRC) initiated a contract with Oak Ridge National Laboratory (ORNL) to calculate radiation dose rates to members of the public that may result from exposure to patients recently administered iodine-131 ( 131I) as part of medical therapy. The main purpose was to compare dose rate estimates based on a point source and target with values derived from more realistic simulations that considered the time-dependent distribution of 131I in the patient and attenuation of emitted photons by the patient’s tissues. The external dose rate estimates were derived using Monte Carlo methods and two representations of themore » Phantom with Movable Arms and Legs, previously developed by ORNL and the USNRC, to model the patient and a nearby member of the public. Dose rates to tissues and effective dose rates were calculated for distances ranging from 10 to 300 cm between the phantoms and compared to estimates based on the point-source method, as well as to results of previous studies that estimated exposure from 131I patients. The point-source method overestimates dose rates to members of the public in very close proximity to an 131I patient but is a broadly accurate method of dose rate estimation at separation distances of 300 cm or more at times closer to administration.« less

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.

Guidelines for Use of the Approximate Beta-Poisson Dose-Response Model.

PubMed

Xie, Gang; Roiko, Anne; Stratton, Helen; Lemckert, Charles; Dunn, Peter K; Mengersen, Kerrie

2017-07-01

For dose-response analysis in quantitative microbial risk assessment (QMRA), the exact beta-Poisson model is a two-parameter mechanistic dose-response model with parameters α>0 and β>0, which involves the Kummer confluent hypergeometric function. Evaluation of a hypergeometric function is a computational challenge. Denoting PI(d) as the probability of infection at a given mean dose d, the widely used dose-response model PI(d)=1-(1+dβ)-α is an approximate formula for the exact beta-Poisson model. Notwithstanding the required conditions α<β and β>1, issues related to the validity and approximation accuracy of this approximate formula have remained largely ignored in practice, partly because these conditions are too general to provide clear guidance. Consequently, this study proposes a probability measure Pr(0 < r < 1 | α̂, β̂) as a validity measure (r is a random variable that follows a gamma distribution; α̂ and β̂ are the maximum likelihood estimates of α and β in the approximate model); and the constraint conditions β̂>(22α̂)0.50 for 0.02<α̂<2 as a rule of thumb to ensure an accurate approximation (e.g., Pr(0 < r < 1 | α̂, β̂) >0.99) . This validity measure and rule of thumb were validated by application to all the completed beta-Poisson models (related to 85 data sets) from the QMRA community portal (QMRA Wiki). The results showed that the higher the probability Pr(0 < r < 1 | α̂, β̂), the better the approximation. The results further showed that, among the total 85 models examined, 68 models were identified as valid approximate model applications, which all had a near perfect match to the corresponding exact beta-Poisson model dose-response curve. © 2016 Society for Risk Analysis.

Consequences of additional use of PET information for target volume delineation and radiotherapy dose distribution for esophageal cancer.

PubMed

Muijs, Christina T; Schreurs, Liesbeth M; Busz, Dianne M; Beukema, Jannet C; van der Borden, Arnout J; Pruim, Jan; Van der Jagt, Eric J; Plukker, John Th; Langendijk, Johannes A

2009-12-01

To determine the consequences of target volume (TV) modifications, based on the additional use of PET information, on radiation planning, assuming PET/CT-imaging represents the true extent of the tumour. For 21 patients with esophageal cancer, two separate TV's were retrospectively defined based on CT (CT-TV) and co-registered PET/CT images (PET/CT-TV). Two 3D-CRT plans (prescribed dose 50.4 Gy) were constructed to cover the corresponding TV's. Subsequently, these plans were compared for target coverage, normal tissue dose-volume histograms and the corresponding normal tissue complication probability (NTCP) values. The addition of PET led to the modification of CT-TV with at least 10% in 12 of 21 patients (57%) (reduction in 9, enlargement in 3). PET/CT-TV was inadequately covered by the CT-based treatment plan in 8 patients (36%). Treatment plan modifications resulted in significant changes (p<0.05) in dose distributions to heart and lungs. Corresponding changes in NTCP values ranged from -3% to +2% for radiation pneumonitis and from -0.2% to +1.2% for cardiac mortality. This study demonstrated that TV's based on CT might exclude PET-avid disease. Consequences are under dosing and thereby possibly ineffective treatment. Moreover, the addition of PET in radiation planning might result in clinical important changes in NTCP.

Evaluation of targeted drenching using Famacha method in Creole goat: reduction of anthelmintic use, and effects on kid production and pasture contamination.

PubMed

Mahieu, Maurice; Arquet, Rémy; Kandassamy, Tony; Mandonnet, Nathalie; Hoste, Hervé

2007-05-15

Haemonchus infection was monitored for 2 years (six kidding periods) in a Creole goat flock grazing under oceanic-tropical climate. Two hundred and thirty individual does were involved from late pregnancy to weaning. Anaemia diagnoses using Famacha method and packed cell volume (PCV) were compared. The best agreement (Kappa=0.33) was found if anaemia was declared when PCV values fell to 16 or below and Famacha score was 4 or 5. Drenching policy according to Famacha method was compared to systematic drenching policy. Using the Famacha method allowed a dramatic decrease in anthelmintic use during the periparturient period (0.57 individual dose instead of three doses for the control). The proportion of the nematode population on the pasture not derived from previously-treated goats (in refugia) was estimated to about 79% (65-90%) of the pasture contamination derived from the Famacha group. On the average, goats which needed to be drenched produced less than the control or undrenched goats (kid average daily gain was decreased by about 15%). The repeatability of the need for drenching individual does was estimated to 0.41. The older goats or the goats in poorer body condition at kidding needed more drenching than the younger animals and the animals in good body condition. Consequently the Famacha method may be used as an additional tool for the culling management.

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.

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.

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.

Calibration of helical tomotherapy machine using EPR/alanine dosimetry.

PubMed

Perichon, Nicolas; Garcia, Tristan; François, Pascal; Lourenço, Valérie; Lesven, Caroline; Bordy, Jean-Marc

2011-03-01

Current codes of practice for clinical reference dosimetry of high-energy photon beams in conventional radiotherapy recommend using a 10 x 10 cm2 square field, with the detector at a reference depth of 10 cm in water and 100 cm source to surface distance (SSD) (AAPM TG-51) or 100 cm source-to-axis distance (SAD) (IAEA TRS-398). However, the maximum field size of a helical tomotherapy (HT) machine is 40 x 5 cm2 defined at 85 cm SAD. These nonstandard conditions prevent a direct implementation of these protocols. The purpose of this study is twofold: To check the absorbed dose in water and dose rate calibration of a tomotherapy unit as well as the accuracy of the tomotherapy treatment planning system (TPS) calculations for a specific test case. Both topics are based on the use of electron paramagnetic resonance (EPR) using alanine as transfer dosimeter between the Laboratoire National Henri Becquerel (LNHB) 60Co-gamma-ray reference beam and the Institut Curie's HT beam. Irradiations performed in the LNHB reference 60Co-gamma-ray beam allowed setting up the calibration method, which was then implemented and tested at the LNHB 6 MV linac x-ray beam, resulting in a deviation of 1.6% (at a 1% standard uncertainty) relative to the reference value determined with the standard IAEA TRS-398 protocol. HT beam dose rate estimation shows a difference of 2% with the value stated by the manufacturer at a 2% standard uncertainty. A 4% deviation between measured dose and the calculation from the tomotherapy TPS was found. The latter was originated by an inadequate representation of the phantom CT-scan values and, consequently, mass densities within the phantom. This difference has been explained by the mass density values given by the CT-scan and used by the TPS which were not the true ones. Once corrected using Monte Carlo N-Particle simulations to validate the accuracy of this process, the difference between corrected TPS calculations and alanine measured dose values was then found to be around 2% (with 2% standard uncertainty on TPS doses and 1.5% standard uncertainty on EPR measurements). Beam dose rate estimation results were found to be in good agreement with the reference value given by the manufacturer at 2% standard uncertainty. Moreover, the dose determination method was set up with a deviation around 2% (at a 2% standard uncertainty).

Estimation of thyroid doses received by the population of Belarus as a result of the Chernobyl accident

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

Gavrilin, Y.; Khrouch, V.; Shinkarev, S.

Within weeks of the Chernobyl accident ABOUT 300,000 measurements of human thyroidal iodine-131 content were conducted in the more contaminated areas of Belarus. Results of these and other measurements form the basis of thyroid-dose reconstruction for the residents. For Class 1 (measured dose), individual doses are estimated directly from measured thyroidal iodine content plus information on life style and dietary habits. Such estimates are available for about 130,000 individuals from Gomel and Mogilev Oblasts and Minsk City. For Class 2 (passport doses), every settlement with a sufficient number of residents with measured doses, individual thyroid-dose distributions were determined for severalmore » age groups and levels of milk consumption. A population of about 2.7 million resides in the passport settlements.« less

Front-line, dose-escalated immunochemotherapy is associated with a significant progression-free survival advantage in patients with double-hit lymphomas: a systematic review and meta-analysis.

PubMed

Howlett, Christina; Snedecor, Sonya J; Landsburg, Daniel J; Svoboda, Jakub; Chong, Elise A; Schuster, Stephen J; Nasta, Sunita Dwivedy; Feldman, Tatyana; Rago, Allison; Walsh, Kristy M; Weber, Scott; Goy, Andre; Mato, Anthony

2015-08-01

'Double-hit lymphomas' (DHL), defined by concurrent MYC and BCL2 (or, alternatively, BCL6) rearrangements, have a very poor outcome compared to standard-risk, diffuse large B-cell lymphomas (DLBCL). Consequently, dose-intensive (DI) therapies and/or consolidation with high-dose therapy and transplant have been explored in DHL, although benefit has been debated. This meta-analysis compared survival outcomes in DHL patients receiving dose-escalated regimens [DI: R-Hyper-CVAD (rituximab, cyclophosphamide, vincristine, doxorubicin, dexamethasone) or R-CODOX-M/IVAC (rituximab, cyclophosphamide, doxorubicin, vincristine, methotrexate/ifosfamide, etoposide, high dose cytarabine); or intermediate-dose: R-EPOCH (rituximab, etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone)] versus standard-dose regimens (R-CHOP; rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) in the first-line setting. Data were synthesized to estimate hazard ratios of dose-escalated treatments versus R-CHOP using a Weibull proportional hazards model within a Bayesian meta-analysis framework. Eleven studies examining 394 patients were included. Patients were treated with either front-line R-CHOP (n = 180), R-EPOCH (n = 91), or R-Hyper-CVAD/rituximab, methotrexate, cytarabine (R-M/C), R-CODOX-M/R-IVAC (DI) (n = 123). Our meta-analysis revealed that median progression-free survival (n = 350) for the R-CHOP, R-EPOCH and DI groups was 12·1, 22·2, and 18·9 months, respectively. First-line treatment with R-EPOCH significantly reduced the risk of a progression compared with R-CHOP (relative risk reduction of 34%; P = 0·032); however, overall survival (n = 374) was not significantly different across treatment approaches. A subset of patients might benefit from intensive induction with/without transplant. Further investigation into the role of transplant and novel therapy combinations is necessary. © 2015 John Wiley & Sons Ltd.

Effect of blood activity on dosimetric calculations for radiopharmaceuticals

NASA Astrophysics Data System (ADS)

Zvereva, Alexandra; Petoussi-Henss, Nina; Li, Wei Bo; Schlattl, Helmut; Oeh, Uwe; Zankl, Maria; Graner, Frank Philipp; Hoeschen, Christoph; Nekolla, Stephan G.; Parodi, Katia; Schwaiger, Markus

2016-11-01

The objective of this work was to investigate the influence of the definition of blood as a distinct source on organ doses, associated with the administration of a novel radiopharmaceutical for positron emission tomography-computed tomography (PET/CT) imaging—(S)-4-(3-18F-fluoropropyl)-L-glutamic acid (18F-FSPG). Personalised pharmacokinetic models were constructed based on clinical PET/CT images from five healthy volunteers and blood samples from four of them. Following an identifiability analysis of the developed compartmental models, person-specific model parameters were estimated using the commercial program SAAM II. Organ doses were calculated in accordance to the formalism promulgated by the Committee on Medical Internal Radiation Dose (MIRD) and the International Commission on Radiological Protection (ICRP) using specific absorbed fractions for photons and electrons previously derived for the ICRP reference adult computational voxel phantoms. Organ doses for two concepts were compared: source organ activities in organs parenchyma with blood as a separate source (concept-1); aggregate activities in perfused source organs without blood as a distinct source (concept-2). Aggregate activities comprise the activities of organs parenchyma and the activity in the regional blood volumes (RBV). Concept-1 resulted in notably higher absorbed doses for most organs, especially non-source organs with substantial blood contents, e.g. lungs (92% maximum difference). Consequently, effective doses increased in concept-1 compared to concept-2 by 3-10%. Not considering the blood as a distinct source region leads to an underestimation of the organ absorbed doses and effective doses. The pronounced influence of the blood even for a radiopharmaceutical with a rapid clearance from the blood, such as 18F-FSPG, suggests that blood should be introduced as a separate compartment in most compartmental pharmacokinetic models and blood should be considered as a distinct source in dosimetric calculations. Hence, blood samples should be included in all pharmacokinetic and dosimetric studies for new tracers if possible.

Solid Cancer Incidence in the Techa River Incidence Cohort: 1956-2007.

PubMed

Davis, F G; Yu, K L; Preston, D; Epifanova, S; Degteva, M; Akleyev, A V

2015-07-01

Previously reported studies of the Techa River Cohort have established associations between radiation dose and the occurrence of solid cancers and leukemia (non-CLL) that appear to be linear in dose response. These analyses include 17,435 cohort members alive and not known to have had cancer prior to January 1, 1956 who lived in areas near the river or Chelyabinsk City at some time between 1956 and the end of 2007, utilized individualized dose estimates computed using the Techa River Dosimetry System 2009 and included five more years of follow-up. The median and mean dose estimates based on these doses are consistently higher than those based on earlier Techa River Dosimetry System 2000 dose estimates. This article includes new site-specific cancer risk estimates and risk estimates adjusted for available information on smoking. There is a statistically significant (P = 0.02) linear trend in the smoking-adjusted all-solid cancer incidence risks with an excess relative risk (ERR) after exposure to 100 mGy of 0.077 with a 95% confidence interval of 0.013-0.15. Examination of site-specific risks revealed statistically significant radiation dose effects only for cancers of the esophagus and uterus with an ERR per 100 mGy estimates in excess of 0.10. Esophageal cancer risk estimates were modified by ethnicity and sex, but not smoking. While the solid cancer rates are attenuated when esophageal cancer is removed (ERR = 0.063 per 100 mGy), a dose-response relationship is present and it remains likely that radiation exposure has increased the risks for most solid cancers in the cohort despite the lack of power to detect statistically significant risks for specific sites.

Fukushima Daiichi Radionuclide Inventories

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

Cardoni, Jeffrey N.; Jankovsky, Zachary Kyle

Radionuclide inventories are generated to permit detailed analyses of the Fukushima Daiichi meltdowns. This is necessary information for severe accident calculations, dose calculations, and source term and consequence analyses. Inventories are calculated using SCALE6 and compared to values predicted by international researchers supporting the OECD/NEA's Benchmark Study on the Accident at Fukushima Daiichi Nuclear Power Station (BSAF). Both sets of inventory information are acceptable for best-estimate analyses of the Fukushima reactors. Consistent nuclear information for severe accident codes, including radionuclide class masses and core decay powers, are also derived from the SCALE6 analyses. Key nuclide activity ratios are calculated asmore » functions of burnup and nuclear data in order to explore the utility for nuclear forensics and support future decommissioning efforts.« less

Dose limits for astronauts

NASA Technical Reports Server (NTRS)

Sinclair, W. K.

2000-01-01

Radiation exposures to individuals in space can greatly exceed natural radiation exposure on Earth and possibly normal occupational radiation exposures as well. Consequently, procedures limiting exposures would be necessary. Limitations were proposed by the Radiobiological Advisory Panel of the National Academy of Sciences/National Research Council in 1970. This panel recommended short-term limits to avoid deterministic effects and a single career limit (of 4 Sv) based on a doubling of the cancer risk in men aged 35 to 55. Later, when risk estimates for cancer had increased and were recognized to be age and sex dependent, the NCRP, in Report No. 98 in 1989, recommended a range of career limits based on age and sex from 1 to 4 Sv. NCRP is again in the process of revising recommendations for astronaut exposure, partly because risk estimates have increased further and partly to recognize trends in limiting radiation exposure occupationally on the ground. The result of these considerations is likely to be similar short-term limits for deterministic effects but modified career limits.

A decade of changes in radiation protection.

PubMed

Moulder, J E

1992-04-01

Although radiation protection standards have changed remarkably little over the past decade, there have been changes in our understanding of radiation hazards that may affect the practice of radiation medicine over the next decade. With recognition of indoor radon exposure has come a new focus for public health concerns, because it is now clear that radon rather than medical exposure is the largest controllable source of radiation exposure to the general public. Continued follow-up of irradiated populations has led to an increase in our estimate of the cancer risk for high-dose exposures; this increased risk estimate is, in turn, leading to decreases in radiation exposure limits. Although our concern about the carcinogenic risk for radiation exposure has increased, our concern about genetic consequences has decreased, because no genetic effects have yet been observed in the offspring of atomic bomb survivors. Studies of atomic bomb survivors have also led to a change in the focus of concern over prenatal radiation exposure; the principle risk now appears to be mental retardation rather than childhood cancer.

Comparison of Individual Radiosensitivity to γ-Rays and Carbon Ions

PubMed Central

Shim, Grace; Normil, Marie Delna; Testard, Isabelle; Hempel, William M.; Ricoul, Michelle; Sabatier, Laure

2016-01-01

Carbon ions are an up-and-coming ion species, currently being used in charged particle radiotherapy. As it is well established that there are considerable interindividual differences in radiosensitivity in the general population that can significantly influence clinical outcomes of radiotherapy, we evaluate the degree of these differences in the context of carbon ion therapy compared with conventional radiotherapy. In this study, we evaluate individual radiosensitivity following exposure to carbon-13 ions or γ-rays in peripheral blood lymphocytes of healthy individuals based on the frequency of ionizing radiation (IR)-induced DNA double strand breaks (DSBs) that was either misrepaired or left unrepaired to form chromosomal aberrations (CAs) (simply referred to here as DSBs for brevity). Levels of DSBs were estimated from the scoring of CAs visualized with telomere/centromere-fluorescence in situ hybridization (TC-FISH). We examine radiosensitivity at the dose of 2 Gy, a routinely administered dose during fractionated radiotherapy, and we determined that a wide range of DSBs were induced by the given dose among healthy individuals, with highly radiosensitive individuals harboring more IR-induced breaks in the genome than radioresistant individuals following exposure to the same dose. Furthermore, we determined the relative effectiveness of carbon irradiation in comparison to γ-irradiation in the induction of DSBs at each studied dose (isodose effect), a quality we term “relative dose effect” (RDE). This ratio is advantageous, as it allows for simple comparison of dose–response curves. At 2 Gy, carbon irradiation was three times more effective in inducing DSBs compared with γ-irradiation (RDE of 3); these results were confirmed using a second cytogenetic technique, multicolor-FISH. We also analyze radiosensitivity at other doses (0.2–15 Gy), to represent hypo- and hyperfractionation doses and determined that RDE is dose dependent: high ratios at low doses, and approaching 1 at high doses. These results could have clinical implications as IR-induced DNA damage and the ensuing CAs and genomic instability can have significant cellular consequences that could potentially have profound implications for long-term human health after IR exposure, such as the emergence of secondary cancers and other pathobiological conditions after radiotherapy. PMID:27379201

Shared dosimetry error in epidemiological dose-response analyses

DOE PAGES

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail; ...

2015-03-23

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of "possible" dose history to workers given dose determinants. This paper takesmore » up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. The use of these methods in the context of several studies including, the Mayak Worker Cohort, and the U.S. Atomic Veterans Study, is discussed.« less

Perfusion CT of the Brain and Liver and of Lung Tumors: Use of Monte Carlo Simulation for Patient Dose Estimation for Examinations With a Cone-Beam 320-MDCT Scanner.

PubMed

Cros, Maria; Geleijns, Jacob; Joemai, Raoul M S; Salvadó, Marçal

2016-01-01

The purpose of this study was to estimate the patient dose from perfusion CT examinations of the brain, lung tumors, and the liver on a cone-beam 320-MDCT scanner using a Monte Carlo simulation and the recommendations of the International Commission on Radiological Protection (ICRP). A Monte Carlo simulation based on the Electron Gamma Shower Version 4 package code was used to calculate organ doses and the effective dose in the reference computational phantoms for an adult man and adult woman as published by the ICRP. Three perfusion CT acquisition protocols--brain, lung tumor, and liver perfusion--were evaluated. Additionally, dose assessments were performed for the skin and for the eye lens. Conversion factors were obtained to estimate effective doses and organ doses from the volume CT dose index and dose-length product. The sex-averaged effective doses were approximately 4 mSv for perfusion CT of the brain and were between 23 and 26 mSv for the perfusion CT body protocols. The eye lens dose from the brain perfusion CT examination was approximately 153 mGy. The sex-averaged peak entrance skin dose (ESD) was 255 mGy for the brain perfusion CT studies, 157 mGy for the lung tumor perfusion CT studies, and 172 mGy for the liver perfusion CT studies. The perfusion CT protocols for imaging the brain, lung tumors, and the liver performed on a 320-MDCT scanner yielded patient doses that are safely below the threshold doses for deterministic effects. The eye lens dose, peak ESD, and effective doses can be estimated for other clinical perfusion CT examinations from the conversion factors that were derived in this study.

Plasma induced DNA damage: Comparison with the effects of ionizing radiation

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

Lazović, S.; Maletić, D.; Puač, N.

2014-09-22

We use human primary fibroblasts for comparing plasma and gamma rays induced DNA damage. In both cases, DNA strand breaks occur, but of fundamentally different nature. Unlike gamma exposure, contact with plasma predominantly leads to single strand breaks and base-damages, while double strand breaks are mainly consequence of the cell repair mechanisms. Different cell signaling mechanisms are detected confirming this (ataxia telangiectasia mutated - ATM and ataxia telangiectasia and Rad3 related - ATR, respectively). The effective plasma doses can be tuned to match the typical therapeutic doses of 2 Gy. Tailoring the effective dose through plasma power and duration of themore » treatment enables safety precautions mainly by inducing apoptosis and consequently reduced frequency of micronuclei.« less

The internal dosimetry of Rubidium-82 based on dynamic PET/CT imaging in humans

NASA Astrophysics Data System (ADS)

Hunter, Chad R.

Rubidium-82 (Rb-82) is a useful blood flow tracer, and has become important in recent years due to the shutdown of the Chalk River reactor. Published effective dose estimates for Rb-82 vary widely, and as yet no comprehensive study in man has been conducted with PET/CT, and no effective dose estimates for Rb-82 during pharmacological stress testing has been published. 30 subjects were recruited for rest, and 25 subjects were recruited for stress. The subjects consisted of both cardiac patients and normal subjects. For rest, a total of 283 organs were measured across 60 scans. For stress, a total of 171 organs were measured across 25 scans. Effective dose estimates were calculated using the ICRP 60, 80, and 103 tissue weighting factors. Relative differences between this study and the published in-vivo estimates showed agreement for the lungs. Relative differences between this study and the blood flow models showed differences> 5 times in the thyroid contribution to the effective dose demonstrating a limitation in these models. Comparisons between rest and stress effective dose estimates revealed no significant difference. The average 'adult' effective dose for Rb-82 was found to be 0.00084+/-0.00018 mSv/MBq. The highest dose organs were the lungs, kidneys and stomach wall. These dose estimates for Rb-82 are the first to be measured directly with PET/CT in humans, and are 4 times lower than previous ICRP 60 values based on a theoretical blood flow model. The total adult effective dose from a typical Rb-82 study including CT for attenuation correction and potential Sr-85 breakthrough is 1.5 +/- 0.4 mSv.

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.

Comparison of behavioral effects of the NMDA receptor channel blockers memantine and ketamine in rats

PubMed Central

Kotermanski, Shawn E.; Johnson, Jon W.; Thiels, Edda

2013-01-01

Memantine and ketamine block N-methyl-D-aspartate (NMDA) receptors with similar affinity and kinetics, yet their behavioral consequences differ: e.g., memantine is used to alleviate symptoms of Alzheimer’s disease, whereas ketamine reproduces symptoms of schizophrenia. The two drugs exhibit different pharmacokinetics, which may play a principal role in their differential behavioral effects. To gain insight into the drugs’ behavioral consequences, we treated adult male rats acutely with varying doses (0–40 mg/kg i.p.) of memantine or ketamine and assessed exploratory behavior and spatial working memory. To examine the importance of pharmacokinetics, we assessed behavior either 15 or 45 min after drug administration. Both drugs decreased ambulation, fine movements, and rearing at the beginning of the exploratory activity test; however, at the end of the test, high doses of only memantine increased ambulation and fine movements. High doses of both drugs disrupted spontaneous alternation, a measure of working memory, but high doses of only memantine elicited perseverative behavior. Surprisingly, ketamine’s effects were influenced by the delay between drug administration and testing no more frequently than were mematine’s. Our findings show that, regardless of test delay, memantine and ketamine evoke similar behavioral effects at lower doses, consistent with NMDA receptors being both drugs’ principal site of action, but can have divergent effects at higher doses. Our results suggest that the divergence of mematine’s and ketamine’s behavioral consequences is likely to result from differences in mechanisms of NMDA receptor antagonism or actions at other receptors. PMID:23665480

Accounting for Shared and Unshared Dosimetric Uncertainties in the Dose Response for Ultrasound-Detected Thyroid Nodules after Exposure to Radioactive Fallout

PubMed Central

Hoffman, F. Owen; Moroz, Brian; Drozdovitch, Vladimir; Bouville, André; Beck, Harold; Luckyanov, Nicholas; Weinstock, Robert M.; Simon, Steven L.

2015-01-01

Dosimetic uncertainties, particularly those that are shared among subgroups of a study population, can bias, distort or reduce the slope or significance of a dose response. Exposure estimates in studies of health risks from environmental radiation exposures are generally highly uncertain and thus, susceptible to these methodological limitations. An analysis was published in 2008 concerning radiation-related thyroid nodule prevalence in a study population of 2,994 villagers under the age of 21 years old between August 1949 and September 1962 and who lived downwind from the Semi-palatinsk Nuclear Test Site in Kazakhstan. This dose-response analysis identified a statistically significant association between thyroid nodule prevalence and reconstructed doses of fallout-related internal and external radiation to the thyroid gland; however, the effects of dosimetric uncertainty were not evaluated since the doses were simple point “best estimates”. In this work, we revised the 2008 study by a comprehensive treatment of dosimetric uncertainties. Our present analysis improves upon the previous study, specifically by accounting for shared and unshared uncertainties in dose estimation and risk analysis, and differs from the 2008 analysis in the following ways: 1. The study population size was reduced from 2,994 to 2,376 subjects, removing 618 persons with uncertain residence histories; 2. Simulation of multiple population dose sets (vectors) was performed using a two-dimensional Monte Carlo dose estimation method; and 3. A Bayesian model averaging approach was employed for evaluating the dose response, explicitly accounting for large and complex uncertainty in dose estimation. The results were compared against conventional regression techniques. The Bayesian approach utilizes 5,000 independent realizations of population dose vectors, each of which corresponds to a set of conditional individual median internal and external doses for the 2,376 subjects. These 5,000 population dose vectors reflect uncertainties in dosimetric parameters, partly shared and partly independent, among individual members of the study population. Risk estimates for thyroid nodules from internal irradiation were higher than those published in 2008, which results, to the best of our knowledge, from explicitly accounting for dose uncertainty. In contrast to earlier findings, the use of Bayesian methods led to the conclusion that the biological effectiveness for internal and external dose was similar. Estimates of excess relative risk per unit dose (ERR/Gy) for males (177 thyroid nodule cases) were almost 30 times those for females (571 cases) and were similar to those reported for thyroid cancers related to childhood exposures to external and internal sources in other studies. For confirmed cases of papillary thyroid cancers (3 in males, 18 in females), the ERR/Gy was also comparable to risk estimates from other studies, but not significantly different from zero. These findings represent the first reported dose response for a radiation epidemiologic study considering all known sources of shared and unshared errors in dose estimation and using a Bayesian model averaging (BMA) method for analysis of the dose response. PMID:25574587

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

Gearhart, A; Carver, D; Stabin, M

Purpose: To validate a radiographic simulation in order to estimate patient dose due to clinically-used radiography protocols. Methods: A Monte Carlo simulation was created to simulate a radiographic x-ray beam using GEANT4. Initial validation was performed according to a portion of TG 195. Computational NURBS-based phantoms were used simulate patients of varying ages and sizes. The deposited energy in the phantom is output by the simulation. The exposure in air from a clinically used radiography unit was measured at 100 cm for various tube potentials. 10 million photons were simulated with 1 cubic centimeter of air located 100 cm frommore » the source, and the total absorbed dose was noted. The normalization factor was determined by taking a ratio of the measured dose in air to the simulated dose in air. Dose to individual voxels is calculated using the energy deposition map along with the voxelized and segmented phantom and the normalization factor. Finally, the effective dose is calculated using the ICRP methodology and tissue weighting factors. Results: This radiography simulation allows for the calculation and visualization of the energy deposition map within a voxelized phantom. The ratio of exposure, measured using an ionization chamber, to air in the simulation was determined. Since the simulation output is calibrated to match the exposure of a given clinical radiographic x-ray tube, the dose map may be visualized. This will also allow for absorbed dose estimation in specific organs or tissues as well as a whole body effective dose estimation. Conclusion: This work indicates that our Monte Carlo simulation may be used to estimate the radiation dose from clinical radiographic protocols. This will allow for an estimate of radiographic dose from various examinations without the use of traditional methods such as thermoluminescent dosimeters and body phantoms.« less

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

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.

Fukushima radionuclides in the NW Pacific, and assessment of doses for Japanese and world population from ingestion of seafood

PubMed Central

Povinec, Pavel P.; Hirose, Katsumi

2015-01-01

Variations of Fukushima-derived radionuclides (90Sr, 134Cs and 137Cs) in seawater and biota offshore Fukushima and in the NW Pacific Ocean were investigated and radiation doses to the Japanese and world population from ingestion of seafood contaminated by Fukushima radionuclides were estimated and compared with those from other sources of anthropogenic and natural radionuclides. The total effective dose commitment from ingestion of radionuclides in fish, shellfish and seaweed caught in coastal waters off Fukushima was estimated to be 0.6 ± 0.4 mSv/y. The individual effective dose commitment from consumption of radioactive-contaminated fish caught in the open Pacific Ocean was estimated to be 0.07 ± 0.05 mSv/y. These doses are comparable or much lower than doses delivered from the consumption of natural 210Po in fish and in shellfish (0.7 mSv/y). The estimated individual doses have been below the levels when any health damage of the Japanese and world population could be expected. PMID:25761420

ESTIMATION OF EARLY INTERNAL DOSES TO FUKUSHIMA RESIDENTS AFTER THE NUCLEAR DISASTER BASED ON THE ATMOSPHERIC DISPERSION SIMULATION.

PubMed

Kim, Eunjoo; Tani, Kotaro; Kunishima, Naoaki; Kurihara, Osamu; Sakai, Kazuo; Akashi, Makoto

2016-11-01

Estimating the early internal doses to residents in the Fukushima Daiichi Nuclear Power Station accident is a difficult task because limited human/environmental measurement data are available. Hence, the feasibility of using atmospheric dispersion simulations created by the Worldwide version of System for Prediction of Environmental Emergency Dose Information 2nd Version (WSPEEDI-II) in the estimation was examined in the present study. This examination was done by comparing the internal doses evaluated based on the human measurements with those calculated using time series air concentration maps ( 131 I and 137 Cs) generated by WSPEEDI-II. The results showed that the latter doses were several times higher than the former doses. However, this discrepancy could be minimised by taking into account personal behaviour data that will be available soon. This article also presents the development of a prototype system for estimating the internal dose based on the simulations. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Fukushima radionuclides in the NW Pacific, and assessment of doses for Japanese and world population from ingestion of seafood.

PubMed

Povinec, Pavel P; Hirose, Katsumi

2015-03-12

Variations of Fukushima-derived radionuclides ((90)Sr, (134)Cs and (137)Cs) in seawater and biota offshore Fukushima and in the NW Pacific Ocean were investigated and radiation doses to the Japanese and world population from ingestion of seafood contaminated by Fukushima radionuclides were estimated and compared with those from other sources of anthropogenic and natural radionuclides. The total effective dose commitment from ingestion of radionuclides in fish, shellfish and seaweed caught in coastal waters off Fukushima was estimated to be 0.6 ± 0.4 mSv/y. The individual effective dose commitment from consumption of radioactive-contaminated fish caught in the open Pacific Ocean was estimated to be 0.07 ± 0.05 mSv/y. These doses are comparable or much lower than doses delivered from the consumption of natural (210)Po in fish and in shellfish (0.7 mSv/y). The estimated individual doses have been below the levels when any health damage of the Japanese and world population could be expected.

Doses from external irradiation to Marshall Islanders from Bikini and Enewetak nuclear weapons tests.

PubMed

Bouville, André; Beck, Harold L; Simon, Steven L

2010-08-01

Annual doses from external irradiation resulting from exposure to fallout from the 65 atmospheric nuclear weapons tests conducted in the Marshall Islands at Bikini and Enewetak between 1946 and 1958 have been estimated for the first time for Marshallese living on all inhabited atolls. All tests that deposited fallout on any of the 23 inhabited atolls or separate reef islands have been considered. The methodology used to estimate the radiation doses at the inhabited atolls is based on test- and location-specific radiation survey data, deposition density estimates of 137Cs, and fallout times-of-arrival provided in a companion paper (Beck et al.), combined with information on the radionuclide composition of the fallout at various times after each test. These estimates of doses from external irradiation have been combined with corresponding estimates of doses from internal irradiation, given in a companion paper (Simon et al.), to assess the cancer risks among the Marshallese population (Land et al.) resulting from exposure to radiation from the nuclear weapons tests.

Dose commitments due to radioactive releases from nuclear power plant sites in 1989

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

Baker, D.A.

Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1989. Fifty-year dose commitments for a one-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses which are compared with 10 CFR Partmore » 50, Appendix I design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 14 person-rem to a low of 0.005 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 1.2 person-rem. The total population dose for all sites was estimated at 84 person-rem for the 140 million people considered at risk. The individual dose commitments estimated for all sites were below the Appendix I design objectives.« less

Dose commitments due to radioactive releases from nuclear power plant sites in 1989. Volume 11

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

Baker, D.A.

Population and individual radiation dose commitments have been estimated from reported radionuclide releases from commercial power reactors operating during 1989. Fifty-year dose commitments for a one-year exposure from both liquid and atmospheric releases were calculated for four population groups (infant, child, teen-ager and adult) residing between 2 and 80 km from each of 72 reactor sites. This report tabulates the results of these calculations, showing the dose commitments for both water and airborne pathways for each age group and organ. Also included for each of the sites is an estimate of individual doses which are compared with 10 CFR Partmore » 50, Appendix I design objectives. The total collective dose commitments (from both liquid and airborne pathways) for each site ranged from a high of 14 person-rem to a low of 0.005 person-rem for the sites with plants in operation and producing power during the year. The arithmetic mean was 1.2 person-rem. The total population dose for all sites was estimated at 84 person-rem for the 140 million people considered at risk. The individual dose commitments estimated for all sites were below the Appendix I design objectives.« less

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

Moore, Bria M.; Brady, Samuel L., E-mail: samuel.brady@stjude.org; Kaufman, Robert A.

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 (CF{sub SSDE}{sup organ}) were then multiplied by patient-specific SSDE to estimate patient organ dose. Themore » CF{sub SSDE}{sup 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. IndividualCF{sub SSDE}{sup organ} were determined for a total of 23 organs in the chest and abdominopelvic region across nine weight subcategories. For organs fully covered by the scan volume, correlation in the chest (average 1.1; range 0.7–1.4) and abdominopelvic region (average 0.9; range 0.7–1.3) was near unity. For organ/tissue that extended beyond the scan volume (i.e., skin, bone marrow, and bone surface), correlation was determined to be poor (average 0.3; range: 0.1–0.4) for both the chest and abdominopelvic regions, respectively. A means to estimate patient organ dose was demonstrated. Calculated patient organ dose, using patient SSDE and CF{sub SSDE}{sup organ}, was compared to previously published pediatric patient doses that accounted for patient size in their dose calculation, and was found to agree in the chest to better than an average of 5% (27.6/26.2) and in the abdominopelvic region to better than 2% (73.4/75.0). Conclusions: For organs fully covered within the scan volume, the average correlation of SSDE and organ absolute dose was found to be better than ±10%. In addition, this study provides a complete list of organ dose correlation factors (CF{sub SSDE}{sup organ}) for the chest and abdominopelvic regions, and describes a simple methodology to estimate individual pediatric patient organ dose based on patient SSDE.« less

Neutrons in active proton therapy: Parameterization of dose and dose equivalent.

PubMed

Schneider, Uwe; Hälg, Roger A; Lomax, Tony

2017-06-01

One of the essential elements of an epidemiological study to decide if proton therapy may be associated with increased or decreased subsequent malignancies compared to photon therapy is an ability to estimate all doses to non-target tissues, including neutron dose. This work therefore aims to predict for patients using proton pencil beam scanning the spatially localized neutron doses and dose equivalents. The proton pencil beam of Gantry 1 at the Paul Scherrer Institute (PSI) was Monte Carlo simulated using GEANT. Based on the simulated neutron dose and neutron spectra an analytical mechanistic dose model was developed. The pencil beam algorithm used for treatment planning at PSI has been extended using the developed model in order to calculate the neutron component of the delivered dose distribution for each treated patient. The neutron dose was estimated for two patient example cases. The analytical neutron dose model represents the three-dimensional Monte Carlo simulated dose distribution up to 85cm from the proton pencil beam with a satisfying precision. The root mean square error between Monte Carlo simulation and model is largest for 138MeV protons and is 19% and 20% for dose and dose equivalent, respectively. The model was successfully integrated into the PSI treatment planning system. In average the neutron dose is increased by 10% or 65% when using 160MeV or 177MeV instead of 138MeV. For the neutron dose equivalent the increase is 8% and 57%. The presented neutron dose calculations allow for estimates of dose that can be used in subsequent epidemiological studies or, should the need arise, to estimate the neutron dose at any point where a subsequent secondary tumour may occur. It was found that the neutron dose to the patient is heavily increased with proton energy. Copyright © 2016. Published by Elsevier GmbH.

Estimation of dose rates at the entrance surface for exposure scenarios of total body irradiation using MCNPX code

NASA Astrophysics Data System (ADS)

Cunha, J. S.; Cavalcante, F. R.; Souza, S. O.; Souza, D. N.; Santos, W. S.; Carvalho Júnior, A. B.

2017-11-01

One of the main criteria that must be held in Total Body Irradiation (TBI) is the uniformity of dose in the body. In TBI procedures the certification that the prescribed doses are absorbed in organs is made with dosimeters positioned on the patient skin. In this work, we modelled TBI scenarios in the MCNPX code to estimate the entrance dose rate in the skin for comparison and validation of simulations with experimental measurements from literature. Dose rates were estimated simulating an ionization chamber laterally positioned on thorax, abdomen, leg and thigh. Four exposure scenarios were simulated: ionization chamber (S1), TBI room (S2), and patient represented by hybrid phantom (S3) and water stylized phantom (S4) in sitting posture. The posture of the patient in experimental work was better represented by S4 compared with hybrid phantom, and this led to minimum and maximum percentage differences of 1.31% and 6.25% to experimental measurements for thorax and thigh regions, respectively. As for all simulations reported here the percentage differences in the estimated dose rates were less than 10%, we considered that the obtained results are consistent with experimental measurements and the modelled scenarios are suitable to estimate the absorbed dose in organs during TBI procedure.

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

Doses and risks from the ingestion of Dounreay fuel fragments.

PubMed

Darley, P J; Charles, M W; Fell, T P; Harrison, J D

2003-01-01

The radiological implications of ingestion of nuclear fuel fragments present in the marine environment around Dounreay have been reassessed by using the Monte Carlo code MCNP to obtain improved estimates of the doses to target cells in the walls of the lower large intestine resulting from the passage of a fragment. The approach takes account of the reduction in dose due to attenuation within the intestinal wall and self-absorption of radiation in the fuel fragment itself. In addition, dose is calculated on the basis of a realistic estimate of the anatomical volume of the lumen, rather than being based on the average mass of the contents, as in the current ICRP model. Our best estimates of doses from the ingestion of the largest Dounreay particles are at least a factor of 30 lower than those predicted using the current ICRP model. The new ICRP model will address the issues raised here and provide improved estimates of dose.

Using machine learning to model dose-response relationships.

PubMed

Linden, Ariel; Yarnold, Paul R; Nallamothu, Brahmajee K

2016-12-01

Establishing the relationship between various doses of an exposure and a response variable is integral to many studies in health care. Linear parametric models, widely used for estimating dose-response relationships, have several limitations. This paper employs the optimal discriminant analysis (ODA) machine-learning algorithm to determine the degree to which exposure dose can be distinguished based on the distribution of the response variable. By framing the dose-response relationship as a classification problem, machine learning can provide the same functionality as conventional models, but can additionally make individual-level predictions, which may be helpful in practical applications like establishing responsiveness to prescribed drug regimens. Using data from a study measuring the responses of blood flow in the forearm to the intra-arterial administration of isoproterenol (separately for 9 black and 13 white men, and pooled), we compare the results estimated from a generalized estimating equations (GEE) model with those estimated using ODA. Generalized estimating equations and ODA both identified many statistically significant dose-response relationships, separately by race and for pooled data. Post hoc comparisons between doses indicated ODA (based on exact P values) was consistently more conservative than GEE (based on estimated P values). Compared with ODA, GEE produced twice as many instances of paradoxical confounding (findings from analysis of pooled data that are inconsistent with findings from analyses stratified by race). Given its unique advantages and greater analytic flexibility, maximum-accuracy machine-learning methods like ODA should be considered as the primary analytic approach in dose-response applications. © 2016 John Wiley & Sons, Ltd.

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

PubMed Central

McAughey, John; Shepperd, Christopher J.

2013-01-01

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. PMID:23742081

[ESTIMATION OF IONIZING RADIATION EFFECTIVE DOSES IN THE INTERNATIONAL SPACE STATION CREWS BY THE METHOD OF CALCULATION MODELING].

PubMed

Mitrikas, V G

2015-01-01

Monitoring of the radiation loading on cosmonauts requires calculation of absorbed dose dynamics with regard to the stay of cosmonauts in specific compartments of the space vehicle that differ in shielding properties and lack means of radiation measurement. The paper discusses different aspects of calculation modeling of radiation effects on human body organs and tissues and reviews the effective dose estimates for cosmonauts working in one or another compartment over the previous period of the International space station operation. It was demonstrated that doses measured by a real or personal dosimeters can be used to calculate effective dose values. Correct estimation of accumulated effective dose can be ensured by consideration for time course of the space radiation quality factor.

Examining Radiation-Induced In Vivo and In Vitro Gene Expression Changes of the Peripheral Blood in Different Laboratories for Biodosimetry Purposes: First RENEB Gene Expression Study.

PubMed

Abend, M; Badie, C; Quintens, R; Kriehuber, R; Manning, G; Macaeva, E; Njima, M; Oskamp, D; Strunz, S; Moertl, S; Doucha-Senf, S; Dahlke, S; Menzel, J; Port, M

2016-02-01

The risk of a large-scale event leading to acute radiation exposure necessitates the development of high-throughput methods for providing rapid individual dose estimates. Our work addresses three goals, which align with the directive of the European Union's Realizing the European Network of Biodosimetry project (EU-RENB): 1. To examine the suitability of different gene expression platforms for biodosimetry purposes; 2. To perform this examination using blood samples collected from prostate cancer patients (in vivo) and from healthy donors (in vitro); and 3. To compare radiation-induced gene expression changes of the in vivo with in vitro blood samples. For the in vitro part of this study, EDTA-treated whole blood was irradiated immediately after venipuncture using single X-ray doses (1 Gy/min(-1) dose rate, 100 keV). Blood samples used to generate calibration curves as well as 10 coded (blinded) samples (0-4 Gy dose range) were incubated for 24 h in vitro, lysed and shipped on wet ice. For the in vivo part of the study PAXgene tubes were used and peripheral blood (2.5 ml) was collected from prostate cancer patients before and 24 h after the first fractionated 2 Gy dose of localized radiotherapy to the pelvis [linear accelerator (LINAC), 580 MU/min, exposure 1-1.5 min]. Assays were run in each laboratory according to locally established protocols using either microarray platforms (2 laboratories) or qRT-PCR (2 laboratories). Report times on dose estimates were documented. The mean absolute difference of estimated doses relative to the true doses (Gy) were calculated. Doses were also merged into binary categories reflecting aspects of clinical/diagnostic relevance. For the in vitro part of the study, the earliest report time on dose estimates was 7 h for qRT-PCR and 35 h for microarrays. Methodological variance of gene expression measurements (CV ≤10% for technical replicates) and interindividual variance (≤twofold for all genes) were low. Dose estimates based on one gene, ferredoxin reductase (FDXR), using qRT-PCR were as precise as dose estimates based on multiple genes using microarrays, but the precision decreased at doses ≥2 Gy. Binary dose categories comprising, for example, unexposed compared with exposed samples, could be completely discriminated with most of our methods. Exposed prostate cancer blood samples (n = 4) could be completely discriminated from unexposed blood samples (n = 4, P < 0.03, two-sided Fisher's exact test) without individual controls. This could be performed by introducing an in vitro-to-in vivo correction factor of FDXR, which varied among the laboratories. After that the in vitro-constructed calibration curves could be used for dose estimation of the in vivo exposed prostate cancer blood samples within an accuracy window of ±0.5 Gy in both contributing qRT-PCR laboratories. In conclusion, early and precise dose estimates can be performed, in particular at doses ≤2 Gy in vitro. Blood samples of prostate cancer patients exposed to 0.09-0.017 Gy could be completely discriminated from pre-exposure blood samples with the doses successfully estimated using adjusted in vitro-constructed calibration curves.

[Brain metastases: Focal treatment (surgery and radiation therapy) and cognitive consequences].

PubMed

Reygagne, Emmanuelle; Du Boisgueheneuc, Foucaud; Berger, Antoine

2017-04-01

Brain metastases represent the first cause of malignant brain tumor. Without radiation therapy, prognosis was poor with fast neurological deterioration, and a median overall survival of one month. Nowadays, therapeutic options depend on brain metastases presentation, extra brain disease, performance status and estimated prognostic (DS GPA). Therefore, for oligometastatic brain patients with a better prognosis, this therapeutic modality is controversial. In fact, whole-brain radiation therapy improves neurological outcomes, but it can also induce late neuro-cognitive sequelae for long-term survivors of brain metastases. Thus, in this strategy for preserving good cognitive functions, stereotactic radiation therapy is a promising treatment. Delivering precisely targeted radiation in few high-doses in one to four brain metastases, allows to reduce radiation damage to normal tissues and it should allow to decrease radiation-induced cognitive decline. In this paper, we will discuss about therapeutic strategies (radiation therapy and surgery) with their neuro-cognitive consequences for brain metastases patients and future concerning preservation of cognitive functions. Copyright © 2016 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.

Patient-specific radiation dose and cancer risk for pediatric chest CT.

PubMed

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

2011-06-01

To estimate patient-specific radiation dose and cancer risk for pediatric chest computed tomography (CT) and to evaluate factors affecting dose and risk, including patient size, patient age, and scanning parameters. The institutional review board approved this study and waived informed consent. This study was HIPAA compliant. The study included 30 patients (0-16 years old), for whom full-body computer models were recently created from clinical CT data. A validated Monte Carlo program was used to estimate organ dose from eight chest protocols, representing clinically relevant combinations of bow tie filter, collimation, pitch, and tube potential. Organ dose was used to calculate effective dose and risk index (an index of total cancer incidence risk). The dose and risk estimates before and after normalization by volume-weighted CT dose index (CTDI(vol)) or dose-length product (DLP) were correlated with patient size and age. The effect of each scanning parameter was studied. Organ dose normalized by tube current-time product or CTDI(vol) decreased exponentially with increasing average chest diameter. Effective dose normalized by tube current-time product or DLP decreased exponentially with increasing chest diameter. Chest diameter was a stronger predictor of dose than weight and total scan length. Risk index normalized by tube current-time product or DLP decreased exponentially with both chest diameter and age. When normalized by DLP, effective dose and risk index were independent of collimation, pitch, and tube potential (<10% variation). The correlations of dose and risk with patient size and age can be used to estimate patient-specific dose and risk. They can further guide the design and optimization of pediatric chest CT protocols. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101900/-/DC1. RSNA, 2011

Biological Consequences and Health Risks Of Low-Level Exposure to Ionizing Radiation: Commentary on the Workshop

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

Feinendegen, Ludwig E.; Brooks, Antone L.; Morgan, William F.

2011-03-01

This paper provides an integration and discussion of the information presented at the workshop held from May 2 to 5, 2010, in Richland, WA, adjacent to the Pacific Northwest National Laboratory (PNNL). Consequently, this is commentary and not necessarily a consensus document. This workshop was in honor of Dr. Victor P. Bond in celebration of his numerous contributions to the radiation sciences. Internationally recognized experts in biophysics, experimental radiation biology, epidemiology, and risk assessment were invited to discuss all issues of low-dose risk. This included the physics of track structure and its consequences to dosimetry, primary and secondary responses atmore » the molecular, cellular, and tissue biology levels, epidemiology, definitions of risk, and the practical and regulatory applications of these issues including their biomedical and social consequences. Of major concern was the present state of knowledge about cancer risk and other risks in humans following intentional or accidental exposures to low doses and low dose-rates of ionizing radiation (below about 100 mSv accumulated dose). This includes low dose exposures which occur during radiation therapy in tissues located outside of the irradiated volume. The interdisciplinary approach of this workshop featured discussions rather than formal presentations in ten separate consecutive sessions. Each session was led by chairpersons, listed in the opening of the workshop, which introduced topics, facts and posed relevant questions. The content of each session is given by a brief summary followed by the abstracts from the primary discussants in the session as has been presented in the previous section. This manuscript provides additional review and discussion of the sessions and tracks the topics and issues discussed as follows: • Energy deposition through particle tracks in tissues. • Energy deposition and primary effects in tissues. • Consequences of experimental advances in radiobiology • Non-targeted radiation effects. • System biological considerations. • Propagation of perturbations in the system. • Immediately operating protections. • Delayed stress response protections • Low-dose induced adaptive protections. • Integrated defenses against cancer. • Endogenous versus radiogenic cancer. • The epidemiological dilemma. • Dose-risk functions for different exposure modalities. • Implications for research. • Implications for regulation and protection. A brief summary of the discussions and results on each of these topics and issues is presented in this paper. Additional details of these discussions are provided in the workshop session summaries grouped into topics and followed by applicable abstracts/synopses submitted by the workshop participants.« less

Development of the Updated Environmental Protection Agency Manual of Protective Action Guides (PAGS) and Protective Actions for Nuclear Incidents

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

Carter, L.M.

2008-07-01

As a student intern with the United States Environmental Protection Agency (EPA) Headquarters, the author was trained in the National Response Plan (NRP) and assisted in the editing of the new (unpublished) EPA Protective Action Guides (PAGs) [1] which has been revised in light of the perceived post 9/11 potential for 'Dirty Bomb' and 'Improvised Nuclear Device' attacks on civilian areas. Technical aspects and the public policy aspects of developing the new guides are discussed. Early Phase initial responses discussed include: Notification of state and/or local authorities, immediate evacuation/sheltering prior to release information or measurements, monitoring of releases and exposuremore » rate measurements, estimation of dose consequences, implementation of protective actions in other areas. The new PAG clarifies the use of 1992 PAGs [2] for incidents other than nuclear power plant accidents, lowers projected thyroid dose for potassium iodine (KI), provides drinking water guidance, includes guidance for long-term site restoration, and updates dosimetry from ICRP 26 to ICRP 60. (authors)« less

Risks from Radon: Reconciling Miner and Residential Epidemiology

NASA Astrophysics Data System (ADS)

Chambers, Douglas B.; Harley, Naomi H.

2008-08-01

Everyone is exposed to radon, an inert radioactive gas that occurs naturally and is present everywhere in the atmosphere. The annual dose from radon and its (short-lived) decay products is typically about one-half of the dose received by members of the public from all natural sources of ionizing radiation. Data on exposures and consequent effects have recently been reviewed by the National Council on Radiation Protection and Measurements (NCRP) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Studies of underground miners provides a well-established basis for estimating risks from occupational exposures to radon and for studying factors that may affect the dose response relationship such as the reduction of risk (coefficients) with increasing time since exposure. Miners' studies previously formed the basis for estimating risks to people exposed to radon at home, with downward extrapolation from exposures in mines to residential levels of radon. Presently, the risk estimates from residential studies are adequate to estimate radon risks in homes. Although there are major uncertainties in extrapolating the risks of exposure to radon from the miner studies to assessing risks in the home, there is remarkably good agreement between the average of risk factors derived from miner studies and those from pooled residential case-control studies. There are now over 20 analytical studies of residential radon and lung cancer. These studies typically assess the relative risk from exposure to radon based on estimates of residential exposure over a period of 25 to 30 years prior to diagnosis of lung cancer. Recent pooled analyses of residential case-control studies support a small but detectable lung cancer risk from residential exposure, and this risk increases with increasing concentrations. The excess relative risk of lung cancer from long-term residential exposure is about the same for both smokers and non-smokers; however, because the baseline lung cancer rate for smokers is much higher than for non or never smokers, smokers account for nearly 90% of the population risk from residential exposure to radon. As described in the paper, an excess relative risk (ERR) of 0.12(95% CI: 0.08-0.2)per 100 Bq m-3 (radon gas) can be estimated from combined miner studies. This compares well with the ERR from pooled residential case-control studies (for restricted analysis) for Europe of 0.16(95% CI: 0.05-0.31)[1] and for North America of 0.11(95% CI: 0.0-0.28)[2].

Assessment of Intrafraction Breathing Motion on Left Anterior Descending Artery Dose During Left-Sided Breast Radiation Therapy

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

El-Sherif, Omar, E-mail: Omar.ElSherif@lhsc.on.ca; Department of Physics, London Regional Cancer Program, London, Ontario; Yu, Edward

Purpose: To use 4-dimensional computed tomography (4D-CT) imaging to predict the level of uncertainty in cardiac dose estimates of the left anterior descending artery that arises due to breathing motion during radiation therapy for left-sided breast cancer. Methods and Materials: The fast helical CT (FH-CT) and 4D-CT of 30 left-sided breast cancer patients were retrospectively analyzed. Treatment plans were created on the FH-CT. The original treatment plan was then superimposed onto all 10 phases of the 4D-CT to quantify the dosimetric impact of respiratory motion through 4D dose accumulation (4D-dose). Dose-volume histograms for the heart, left ventricle (LV), and left anteriormore » descending (LAD) artery obtained from the FH-CT were compared with those obtained from the 4D-dose. Results: The 95% confidence interval of 4D-dose and FH-CT differences in mean dose estimates for the heart, LV, and LAD were ±0.5 Gy, ±1.0 Gy, and ±8.7 Gy, respectively. Conclusion: Fast helical CT is a good approximation for doses to the heart and LV; however, dose estimates for the LAD are susceptible to uncertainties that arise due to intrafraction breathing motion that cannot be ascertained without the additional information obtained from 4D-CT and dose accumulation. For future clinical studies, we suggest the use of 4D-CT–derived dose-volume histograms for estimating the dose to the LAD.« less

Organ dose conversion coefficients for tube current modulated CT protocols for an adult population

NASA Astrophysics Data System (ADS)

Fu, Wanyi; Tian, Xiaoyu; Sahbaee, Pooyan; Zhang, Yakun; Segars, William Paul; Samei, Ehsan

2016-03-01

In computed tomography (CT), patient-specific organ dose can be estimated using pre-calculated organ dose conversion coefficients (organ dose normalized by CTDIvol, h factor) database, taking into account patient size and scan coverage. The conversion coefficients have been previously estimated for routine body protocol classes, grouped by scan coverage, across an adult population for fixed tube current modulated CT. The coefficients, however, do not include the widely utilized tube current (mA) modulation scheme, which significantly impacts organ dose. This study aims to extend the h factors and the corresponding dose length product (DLP) to create effective dose conversion coefficients (k factor) database incorporating various tube current modulation strengths. Fifty-eight extended cardiac-torso (XCAT) phantoms were included in this study representing population anatomy variation in clinical practice. Four mA profiles, representing weak to strong mA dependency on body attenuation, were generated for each phantom and protocol class. A validated Monte Carlo program was used to simulate the organ dose. The organ dose and effective dose was further normalized by CTDIvol and DLP to derive the h factors and k factors, respectively. The h factors and k factors were summarized in an exponential regression model as a function of body size. Such a population-based mathematical model can provide a comprehensive organ dose estimation given body size and CTDIvol. The model was integrated into an iPhone app XCATdose version 2, enhancing the 1st version based upon fixed tube current modulation. With the organ dose calculator, physicists, physicians, and patients can conveniently estimate organ dose.

SU-E-I-57: Estimating the Occupational Eye Lens Dose in Interventional Radiology Using Active Personal Dosimeters Worn On the Chest

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

Omar, A; Marteinsdottir, M; Kadesjo, N

Purpose: To provide a general formalism for determination of occupational eye lens dose based on the response of an active personal dosimeter (APD) worn at chest level above the radiation protection apron. Methods: The formalism consists of three factors: (1) APD conversion factor converting the reading at chest level (APDchest) to the corresponding personal dose equivalent at eye level, (2) Dose conversion factor transferring the measured dose quantity, Hp(10), into a dose quantity relevant for the eye lens dose, (3) Correction factor accounting for differences in exposure of the eye(s) compared to the exposure at chest level (e.g., due tomore » protective lead glasses).The different factors were investigated and evaluated based on phantom and clinical measurements performed in an x-ray angiography suite for interventional cardiology. Results: The eye lens dose can be conservatively estimated by assigning an appropriate numerical value to each factor entering the formalism that in most circumstances overestimates the dose. Doing so, the eye lens dose to the primary operator and assisting staff was estimated in this work as D-eye,primary = 2.0 APDchest and D-eye,assisting = 1.0 APDchest, respectively.The annual eye lens dose to three nurses and one cardiologist was estimated to be 2, 2, 2, and 13 mSv (Hp(0.07)), respectively, using a TLD dosimeter worn at eye level. In comparison, using the formalism and APDchest measurements, the respective doses were 2, 2, 2, and 16 mSv (Hp(3)). Conclusion: The formalism outlined in this work can be used to estimate the occupational eye lens dose from the response of an APD worn on the chest. The formalism is general and could be applied also to other types of dosimeters. However, the numerical value of the different factors may differ from those obtained with the APD’s used in this work due to differences in dosimeter properties.« less

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 made using the method developed in the current study.« less

Individual Radiological Protection Monitoring of Utrok Atoll Residents Based on Whole Body Counting of Cesium-137 (137Cs) and Plutonium Bioassay

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

Hamilton, T; Kehl, S; Brown, T

2007-06-08

This report contains individual radiological protection surveillance data developed during 2006 for adult members of a select group of families living on Utrok Atoll. These Group I volunteers all underwent a whole-body count to determine levels of internally deposited cesium-137 ({sup 137}Cs) and supplied a bioassay sample for analysis of plutonium isotopes. Measurement data were obtained and the results compared with an equivalent set of measurement data for {sup 137}Cs and plutonium isotopes from a second group of adult volunteers (Group II) who were long-term residents of Utrok Atoll. For the purposes of this comparison, Group II volunteers were consideredmore » representative of the general population on Utrok Atoll. The general aim of the study was to determine residual systemic burdens of fallout radionuclides in each volunteer group, develop data in response to addressing some specific concerns about the preferential uptake and potential health consequences of residual fallout radionuclides in Group I volunteers, and generally provide some perspective on the significance of radiation doses delivered to volunteers (and the general Utrok Atoll resident population) in terms of radiological protection standards and health risks. Based on dose estimates from measurements of internally deposited {sup 137}Cs and plutonium isotopes, the data and information developed in this report clearly show that neither volunteer group has acquired levels of internally deposited fallout radionuclides specific to nuclear weapons testing in the Marshall Islands that are likely to have any consequence on human health. Moreover, the dose estimates are well below radiological protection standards as prescribed by U.S. regulators and international agencies, and are very small when compared to doses from natural sources of radiation in the Marshall Islands and the threshold where radiation health effects could be either medically diagnosed in an individual or epidemiologically discerned in a group of people. In general, the results from the whole-body counting measurements of 137Cs are consistent with our knowledge that a key pathway for exposure to residual fallout contamination on Utrok Atoll is low-level chronic uptake of {sup 137}Cs from the consumption of locally grown produce (Robison et al., 1999). The error-weighted, average body burden of {sup 137}Cs measured in Group I and Group II volunteers was 0.31 kBq and 0.62 kBq, respectively. The associated average, annual committed effective dose equivalent (CEDE) delivered to Group I and Group II volunteers from {sup 137}Cs during the year of measurement was 2.1 and 4.0 mrem. For comparative purposes, the annual dose limit for members of the public as recommended by the National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP) is 100 mrem. Consequently, specific concerns about elevated levels of {sup 137}Cs uptake and higher risks from radiation exposure to Group I volunteers would be considered unfounded. Moreover, the urinary excretion of plutonium-239 ({sup 239}Pu) from Group I and Group II volunteers is statistically indistinguishable. In this case, the error-weighted, average urinary excretion of {sup 239}Pu from Group I volunteers of 0.10 {mu}Bq per 24-h void with a range between -0.01 and 0.23 {mu}Bq per 24-h void compares with an error-weighted average from Group II volunteers of 0.11 {mu}Bq per 24-h void with a range between -0.20 and 0.47 {mu}Bq per 24-h void. The range in urinary excretion of {sup 239}Pu from Utrok Atoll residents is very similar to that observed for other population groups in the Marshall Islands (Bogen et al., 2006; Hamilton et al., 2006a; 2006b; 2006c, 2007a; 2007b; 2007c) and is generally considered representative of worldwide background.« less

Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

PubMed

Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

2010-03-01

The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry.

Estimating peak skin and eye lens dose from neuroperfusion examinations: use of Monte Carlo based simulations and comparisons to CTDIvol, AAPM Report No. 111, and ImPACT dosimetry tool values.

PubMed

Zhang, Di; Cagnon, Chris H; Villablanca, J Pablo; McCollough, Cynthia H; Cody, Dianna D; Zankl, Maria; Demarco, John J; McNitt-Gray, Michael F

2013-09-01

CT neuroperfusion examinations are capable of delivering high radiation dose to the skin or lens of the eyes of a patient and can possibly cause deterministic radiation injury. The purpose of this study is to: (a) estimate peak skin dose and eye lens dose from CT neuroperfusion examinations based on several voxelized adult patient models of different head size and (b) investigate how well those doses can be approximated by some commonly used CT dose metrics or tools, such as CTDIvol, American Association of Physicists in Medicine (AAPM) Report No. 111 style peak dose measurements, and the ImPACT organ dose calculator spreadsheet. Monte Carlo simulation methods were used to estimate peak skin and eye lens dose on voxelized patient models, including GSF's Irene, Frank, Donna, and Golem, on four scanners from the major manufacturers at the widest collimation under all available tube potentials. Doses were reported on a per 100 mAs basis. CTDIvol measurements for a 16 cm CTDI phantom, AAPM Report No. 111 style peak dose measurements, and ImPACT calculations were performed for available scanners at all tube potentials. These were then compared with results from Monte Carlo simulations. The dose variations across the different voxelized patient models were small. Dependent on the tube potential and scanner and patient model, CTDIvol values overestimated peak skin dose by 26%-65%, and overestimated eye lens dose by 33%-106%, when compared to Monte Carlo simulations. AAPM Report No. 111 style measurements were much closer to peak skin estimates ranging from a 14% underestimate to a 33% overestimate, and with eye lens dose estimates ranging from a 9% underestimate to a 66% overestimate. The ImPACT spreadsheet overestimated eye lens dose by 2%-82% relative to voxelized model simulations. CTDIvol consistently overestimates dose to eye lens and skin. The ImPACT tool also overestimated dose to eye lenses. As such they are still useful as a conservative predictor of dose for CT neuroperfusion studies. AAPM Report No. 111 style measurements are a better predictor of both peak skin and eye lens dose than CTDIvol and ImPACT for the patient models used in this study. It should be remembered that both the AAPM Report No. 111 peak dose metric and CTDIvol dose metric are dose indices and were not intended to represent actual organ doses.

Estimating peak skin and eye lens dose from neuroperfusion examinations: Use of Monte Carlo based simulations and comparisons to CTDIvol, AAPM Report No. 111, and ImPACT dosimetry tool values

PubMed Central

Zhang, Di; Cagnon, Chris H.; Villablanca, J. Pablo; McCollough, Cynthia H.; Cody, Dianna D.; Zankl, Maria; Demarco, John J.; McNitt-Gray, Michael F.

2013-01-01

Purpose: CT neuroperfusion examinations are capable of delivering high radiation dose to the skin or lens of the eyes of a patient and can possibly cause deterministic radiation injury. The purpose of this study is to: (a) estimate peak skin dose and eye lens dose from CT neuroperfusion examinations based on several voxelized adult patient models of different head size and (b) investigate how well those doses can be approximated by some commonly used CT dose metrics or tools, such as CTDIvol, American Association of Physicists in Medicine (AAPM) Report No. 111 style peak dose measurements, and the ImPACT organ dose calculator spreadsheet. Methods: Monte Carlo simulation methods were used to estimate peak skin and eye lens dose on voxelized patient models, including GSF's Irene, Frank, Donna, and Golem, on four scanners from the major manufacturers at the widest collimation under all available tube potentials. Doses were reported on a per 100 mAs basis. CTDIvol measurements for a 16 cm CTDI phantom, AAPM Report No. 111 style peak dose measurements, and ImPACT calculations were performed for available scanners at all tube potentials. These were then compared with results from Monte Carlo simulations. Results: The dose variations across the different voxelized patient models were small. Dependent on the tube potential and scanner and patient model, CTDIvol values overestimated peak skin dose by 26%–65%, and overestimated eye lens dose by 33%–106%, when compared to Monte Carlo simulations. AAPM Report No. 111 style measurements were much closer to peak skin estimates ranging from a 14% underestimate to a 33% overestimate, and with eye lens dose estimates ranging from a 9% underestimate to a 66% overestimate. The ImPACT spreadsheet overestimated eye lens dose by 2%–82% relative to voxelized model simulations. Conclusions: CTDIvol consistently overestimates dose to eye lens and skin. The ImPACT tool also overestimated dose to eye lenses. As such they are still useful as a conservative predictor of dose for CT neuroperfusion studies. AAPM Report No. 111 style measurements are a better predictor of both peak skin and eye lens dose than CTDIvol and ImPACT for the patient models used in this study. It should be remembered that both the AAPM Report No. 111 peak dose metric and CTDIvol dose metric are dose indices and were not intended to represent actual organ doses. PMID:24007152

ANALYSIS OF EPR AND FISH STUDIES OF RADIATION DOSES IN PERSONS WHO LIVED IN THE UPPER REACHES OF THE TECHA RIVER

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

Degteva, M. O.; Shagina, N. B.; Shishkina, Elena A.

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949–1956 resulted in significant doses to about 30,000 persons who lived in downstream settlements. The residents were exposed to internal and external radiation. Two methods for reconstruction of the external dose are considered in this paper, electron paramagnetic resonance (EPR) measurements of teeth and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. The main issue in the application of the EPR and FISH methods for reconstruction of the external dose for the Techa Riverside residents was strontium radioisotopes incorporated in teethmore » and bones that served as a source of confounding local exposures. In order to estimate and subtract doses from incorporated 89,90Sr, the EPR and FISH assays were supported by measurements of 90Sr-body burdens and estimates of 90Sr concentrations in dental tissues by the luminescence method. The resulting dose estimates derived from EPR and FISH measurements for residents of the upper Techa River were found to be consistent: the mean values vary from 510 – 550 mGy for the villages located close to the site of radioactive release to 130 – 160 mGy for the more distant villages. The upper bound of individual estimates for both methods is equal to 2.2 – 2.3 Gy. The EPR- and FISH-based dose estimates were compared with the doses calculated for the donors using the Techa River Dosimetry System (TRDS). The TRDS external dose assessments were based on the data on contamination of the Techa River floodplain, simulation of ai r kerma above the contaminated soil, age-dependent life-styles and individual residence histories. For correct comparison TRDS-based doses were calculated from two sources: external exposure from the contaminated environment and internal exposure from 137Cs incorporated in donors’ soft tissues. The TRDS-based absorbed doses in tooth enamel and muscle were in agreement with with EPR- and FISH-based estimates within uncertainty bounds. Basically, the agreement between the estimates has confirmed the validity of external doses calculated with the Techa River Dosimetry System.« less

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...

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...

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

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-intensive representative CT-based method. This simpler method may produce a meaningful measure of mean heart dose for use in studies of late cardiac complications.« less

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 meaningful measure of mean heart dose for use in studies of late cardiac complications. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

An estimation of Canadian population exposure to cosmic rays from air travel.

PubMed

Chen, Jing; Newton, Dustin

2013-03-01

Based on air travel statistics in 1984, it was estimated that less than 4 % of the population dose from cosmic ray exposure would result from air travel. In the present study, cosmic ray doses were calculated for more than 3,000 flights departing from more than 200 Canadian airports using actual flight profiles. Based on currently available air travel statistics, the annual per capita effective dose from air transportation is estimated to be 32 μSv for Canadians, about 10 % of the average cosmic ray dose received at ground level (310 μSv per year).

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.

PARMA: PHITS-based Analytical Radiation Model in the Atmosphere--Verification of Its Accuracy in Estimating Cosmic Radiation Doses

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

Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira

Estimation of cosmic-ray spectra in the atmosphere has been an essential issue in the evaluation of the aircrew doses. We therefore developed an analytical model that can predict the terrestrial neutron, proton, He nucleus, muon, electron, positron and photon spectra at altitudes below 20 km, based on the Monte Carlo simulation results of cosmic-ray propagation in the atmosphere performed by the PHITS code. The model was designated PARMA. In order to examine the accuracy of PARMA in terms of the neutron dose estimation, we measured the neutron dose rates at the altitudes between 20 to 10400 m, using our developedmore » dose monitor DARWIN mounted on an aircraft. Excellent agreement was observed between the measured dose rates and the corresponding data calculated by PARMA coupled with the fluence-to-dose conversion coefficients, indicating the applicability of the model to be utilized in the route-dose calculation.« less

Patient-specific Radiation Dose and Cancer Risk for Pediatric Chest CT

PubMed Central

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

2011-01-01

Purpose: To estimate patient-specific radiation dose and cancer risk for pediatric chest computed tomography (CT) and to evaluate factors affecting dose and risk, including patient size, patient age, and scanning parameters. Materials and Methods: The institutional review board approved this study and waived informed consent. This study was HIPAA compliant. The study included 30 patients (0–16 years old), for whom full-body computer models were recently created from clinical CT data. A validated Monte Carlo program was used to estimate organ dose from eight chest protocols, representing clinically relevant combinations of bow tie filter, collimation, pitch, and tube potential. Organ dose was used to calculate effective dose and risk index (an index of total cancer incidence risk). The dose and risk estimates before and after normalization by volume-weighted CT dose index (CTDIvol) or dose–length product (DLP) were correlated with patient size and age. The effect of each scanning parameter was studied. Results: Organ dose normalized by tube current–time product or CTDIvol decreased exponentially with increasing average chest diameter. Effective dose normalized by tube current–time product or DLP decreased exponentially with increasing chest diameter. Chest diameter was a stronger predictor of dose than weight and total scan length. Risk index normalized by tube current–time product or DLP decreased exponentially with both chest diameter and age. When normalized by DLP, effective dose and risk index were independent of collimation, pitch, and tube potential (<10% variation). Conclusion: The correlations of dose and risk with patient size and age can be used to estimate patient-specific dose and risk. They can further guide the design and optimization of pediatric chest CT protocols. © RSNA, 2011 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101900/-/DC1 PMID:21467251

SU-F-T-258: Efficacy of Exit Fluence-Based Dose Calculation for Prostate Radiation Therapy

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

Siebers, J; Gardner, J; Neal, B

Purpose: To investigate the efficacy of exit-fluence-based dose computation for prostate radiotherapy by determining if it estimates true dose more accurately than the original planning dose. Methods: Virtual exit-fluencebased dose computation was performed for 19 patients, each with 9–12 repeat CT images. For each patient, a 78 Gy treatment plan was created utilizing 5 mm CTV-to-PTV and OAR-to-PRV margins. A Monte Carlo framework was used to compute dose and exit-fluence images for the planning image and for each repeat CT image based on boney-anatomyaligned and prostate-centroid-aligned CTs. Identical source particles were used for the MC dose-computations on the planning andmore » repeat CTs to maximize correlation. The exit-fluence-based dose and image were computed by multiplying source particle weights by FC(x,y)=FP(x,y)/FT(x,y), where (x,y) are the source particle coordinates projected to the exit-fluence plane and we denote the dose/fluence from the plan by (DP,FP), from the repeat-CT as (DT,FT), and the exit-fluence computation by (DFC,FFC). DFC mimics exit-fluence backprojection through the planning image as FT=FFC. Dose estimates were intercompared to judge the efficacy of exit-fluence-based dose computation. Results: Boney- and prostate-centroid aligned results are combined as there is no statistical difference between them, yielding 420 dose comparisons per dose-volume metric. DFC is more accurate than DP for 46%, 33%, and 44% of cases in estimating CTV D98, D50, and D2 respectively. DFC improved rectum D50 and D2 estimates 54% and 49% respectively and bladder D50 and D2 47 and 49% respectively. While averaged over all patients and images DFC and DP were within 3.1% of DT, they differed from DT by as much as 22% for GTV D98, 71% for the Bladder D50, 17% for Bladder D2, 19% for Rectum D2. Conclusion: Exit-fluence based dose computations infrequently improve CTV or OAR dose estimates and should be used with caution. Research supported in part by Varian Medical Systems.« less

USE OF EXPOSURE RELATED DOSE ESTIMATING MODEL ( ERDEM ) TO CONSTRUCT A PBPK /MODEL FOR CARBOFURAN WITH THE REPORTED EXPERIMENTAL DATA IN THE RAT

EPA Science Inventory

To better understand the relationships among carbofuran exposure, dose, and effects, a physiologically-based pharmacokinetic and pharmacodynamic (PBPK/PD) model was developed for the rat using the Exposure Related Dose Estimating Model (ERDEM) framework.

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...

Development of a dosimeter for distributed body organs

NASA Technical Reports Server (NTRS)

Khandelwal, G. S.

1976-01-01

Calculational methods for estimation of dose from external proton exposure of aribtrary convex bodies is briefly reviewed and all of the necessary information for the estimation of dose in soft tissue is presented. Special emphasis is on retaining the effects of nuclear reaction especially in relation to the dose equivalent.

Optimal mapping of terrestrial gamma dose rates using geological parent material and aerogeophysical survey data.

PubMed

Rawlins, B G; Scheib, C; Tyler, A N; Beamish, D

2012-12-01

Regulatory authorities need ways to estimate natural terrestrial gamma radiation dose rates (nGy h⁻¹) across the landscape accurately, to assess its potential deleterious health effects. The primary method for estimating outdoor dose rate is to use an in situ detector supported 1 m above the ground, but such measurements are costly and cannot capture the landscape-scale variation in dose rates which are associated with changes in soil and parent material mineralogy. We investigate the potential for improving estimates of terrestrial gamma dose rates across Northern Ireland (13,542 km²) using measurements from 168 sites and two sources of ancillary data: (i) a map based on a simplified classification of soil parent material, and (ii) dose estimates from a national-scale, airborne radiometric survey. We used the linear mixed modelling framework in which the two ancillary variables were included in separate models as fixed effects, plus a correlation structure which captures the spatially correlated variance component. We used a cross-validation procedure to determine the magnitude of the prediction errors for the different models. We removed a random subset of 10 terrestrial measurements and formed the model from the remainder (n = 158), and then used the model to predict values at the other 10 sites. We repeated this procedure 50 times. The measurements of terrestrial dose vary between 1 and 103 (nGy h⁻¹). The median absolute model prediction errors (nGy h⁻¹) for the three models declined in the following order: no ancillary data (10.8) > simple geological classification (8.3) > airborne radiometric dose (5.4) as a single fixed effect. Estimates of airborne radiometric gamma dose rate can significantly improve the spatial prediction of terrestrial dose rate.

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.

Long-term erythemal UV doses at Sodankylä estimated using total ozone, sunshine duration and snow depth

NASA Astrophysics Data System (ADS)

Lindfors, A. V.; Arola, A.; Kaurola, J.; Taalas, P.; Svenøe, T.

2003-04-01

A method for estimating daily erythemal UV doses using total ozone, sunshine duration and snow depth has been developed. The method consists of three steps: (1) daily clear-sky UV doses were simulated using the UVSPEC radiative transfer program, with daily values of total ozone as input data, (2) an empirical relationship was sought between the simulated clear-sky UV doses, the measured UV doses and the duration of bright sunshine, (3) daily erythemal UV doses were estimated using this relationship. The method accounts for the varying surface albedo by dividing the period of interest into winter and summer days, depending on the snow depth. Using this method, the daily erythemal UV doses at Sodankylä were estimated for the period 1950--99. This was done using Tromsø's total ozone together with Sodankylä's own sunshine duration and snow depth as input data. Although the method is fairly simple, the results are in good agreement, even on the daily scale, with the UV radiation measured with the Brewer spectrophotometer at Sodankylä. Statistically significant increasing trends in erythemal UV doses of a few percents per decade over the period 1950--99 were found for March and April, suggesting a connection to the stratospheric ozone depletion. For July, on the other hand, a significant decreasing trend of about 3% per decade, supported by the changes in both total ozone and sunshine duration, was found. The produced data set of erythemal UV doses is the longest time series of estimated UV known to the authors.

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.

Evaluation of potential hazard exposure resulting from DOE waste treatment and disposal at Rollins Environmental Services, Baton Rouge, LA

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

Not Available

1992-04-01

The equivalent dose rate to populations potentially exposed to wastes shipped to Rollins Environmental Services, Baton Rouge, LA from Oak Ridge and Savannah River Operations of the Department of Energy was estimated. Where definitive information necessary to the estimation of a dose rate was unavailable, bounding assumptions were employed to ensure an overestimate of the actual dose rate experienced by the potentially exposed population. On this basis, it was estimated that a total of about 3.85 million pounds of waste was shipped from these DOE operations to Rollins with a maximum combined total activity of about 0.048 Curies. Populations nearmore » the Rollins site could potentially be exposed to the radionuclides in the DOE wastes via the air pathway after incineration of the DOE wastes or by migration from the soil after landfill disposal. AIRDOS was used to estimate the dose rate after incineration. RESRAD was used to estimate the dose rate after landfill disposal. Calculations were conducted with the estimated radioactive specie distribution in the wastes and, as a test of the sensitivity of the results to the estimated distribution, with the entire activity associated with individual radioactive species such as Cs-137, Ba-137, Sr-90, Co-60, U-234, U-235 and U-238. With a given total activity, the dose rates to nearby individuals were dominated by the uranium species.« less

ACUTE AND CHRONIC INTAKES OF FALLOUT RADIONUCLIDES BY MARSHALLESE FROM NUCLEAR WEAPONS TESTING AT BIKINI AND ENEWETAK AND RELATED INTERNAL RADIATION DOSES

PubMed Central

Simon, Steven L.; Bouville, André; Melo, Dunstana; Beck, Harold L.; Weinstock, Robert M.

2014-01-01

Annual internal radiation doses resulting from both acute and chronic intakes of all important dose-contributing radionuclides occurring in fallout from nuclear weapons testing at Bikini and Enewetak from 1946 through 1958 have been estimated for the residents living on all atolls and separate reef islands of the Marshall Islands. Internal radiation absorbed doses to the tissues most at risk to cancer induction (red bone marrow, thyroid, stomach, and colon) have been estimated for representative persons of all population communities for all birth years from 1929 through 1968, and for all years of exposure from 1948 through 1970. The acute intake estimates rely on a model using, as its basis, historical urine bioassay data, for members of the Rongelap Island and Ailinginae communities as well as for Rongerik residents. The model also utilizes fallout times of arrival and radionuclide deposition densities estimated for all tests and all atolls. Acute intakes of 63 radionuclides were estimated for the populations of the 20 inhabited atolls and for the communities that were relocated during the testing years for reasons of safety and decontamination. The model used for chronic intake estimates is based on reported whole-body, urine, and blood counting data for residents of Utrik and Rongelap. Dose conversion coefficients relating intake to organ absorbed dose were developed using internationally accepted models but specifically tailored for intakes of particulate fallout by consideration of literature-based evidence to choose the most appropriate alimentary tract absorption fraction (f1) values. Dose estimates were much higher for the thyroid gland than for red marrow, stomach wall, or colon. The highest thyroid doses to adults were about 7,600 mGy for the people exposed on Rongelap; thyroid doses to adults were much lower, by a factor of 100 or more, for the people exposed on the populated atolls of Kwajalein and Majuro. The estimates of radionuclide intake and internal radiation dose to the Marshallese that are presented in this paper are the most complete available anywhere and were used to make projections of lifetime cancer risks to the exposed populations, which are presented in a companion paper in this volume. PMID:20622550

Acute and chronic intakes of fallout radionuclides by Marshallese from nuclear weapons testing at Bikini and Enewetak and related internal radiation doses.

PubMed

Simon, Steven L; Bouville, André; Melo, Dunstana; Beck, Harold L; Weinstock, Robert M

2010-08-01

Annual internal radiation doses resulting from both acute and chronic intakes of all important dose-contributing radionuclides occurring in fallout from nuclear weapons testing at Bikini and Enewetak from 1946 through 1958 have been estimated for the residents living on all atolls and separate reef islands of the Marshall Islands. Internal radiation absorbed doses to the tissues most at risk to cancer induction (red bone marrow, thyroid, stomach, and colon) have been estimated for representative persons of all population communities for all birth years from 1929 through 1968, and for all years of exposure from 1948 through 1970. The acute intake estimates rely on a model using, as its basis, historical urine bioassay data, for members of the Rongelap Island and Ailinginae communities as well as for Rongerik residents. The model also utilizes fallout times of arrival and radionuclide deposition densities estimated for all tests and all atolls. Acute intakes of 63 radionuclides were estimated for the populations of the 20 inhabited atolls and for the communities that were relocated during the testing years for reasons of safety and decontamination. The model used for chronic intake estimates is based on reported whole-body, urine, and blood counting data for residents of Utrik and Rongelap. Dose conversion coefficients relating intake to organ absorbed dose were developed using internationally accepted models but specifically tailored for intakes of particulate fallout by consideration of literature-based evidence to choose the most appropriate alimentary tract absorption fraction (f1) values. Dose estimates were much higher for the thyroid gland than for red marrow, stomach wall, or colon. The highest thyroid doses to adults were about 7,600 mGy for the people exposed on Rongelap; thyroid doses to adults were much lower, by a factor of 100 or more, for the people exposed on the populated atolls of Kwajalein and Majuro. The estimates of radionuclide intake and internal radiation dose to the Marshallese that are presented in this paper are the most complete available anywhere and were used to make projections of lifetime cancer risks to the exposed populations, which are presented in a companion paper in this volume.

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

The Internet's role in a biodosimetric response to a radiation mass casualty event.

PubMed

Sugarman, S L; Livingston, G K; Stricklin, D L; Abbott, M G; Wilkins, R C; Romm, H; Oestreicher, U; Yoshida, M A; Miura, T; Moquet, J E; Di Giorgio, M; Ferrarotto, C; Gross, G A; Christiansen, M E; Hart, C L; Christensen, D M

2014-05-01

Response to a large-scale radiological incident could require timely medical interventions to minimize radiation casualties. Proper medical care requires knowing the victim's radiation dose. When physical dosimetry is absent, radiation-specific chromosome aberration analysis can serve to estimate the absorbed dose in order to assist physicians in the medical management of radiation injuries. A mock exercise scenario was presented to six participating biodosimetry laboratories as one individual acutely exposed to Co under conditions suggesting whole-body exposure. The individual was not wearing a dosimeter and within 2-3 h of the incident began vomiting. The individual also had other medical symptoms indicating likelihood of a significant dose. Physicians managing the patient requested a dose estimate in order to develop a treatment plan. Participating laboratories in North and South America, Europe, and Asia were asked to evaluate more than 800 electronic images of metaphase cells from the patient to determine the dicentric yield and calculate a dose estimate with 95% confidence limits. All participants were blind to the physical dose until after submitting their estimates based on the dicentric chromosome assay (DCA). The exercise was successful since the mean biological dose estimate was 1.89 Gy whereas the actual physical dose was 2 Gy. This is well within the requirements for guidance of medical management. The exercise demonstrated that the most labor-intensive step in the entire process (visual evaluation of images) can be accelerated by taking advantage of world-wide expertise available on the Internet.

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

Validation of ELDO approaches for retrospective assessment of cumulative eye lens doses of interventional cardiologists-results from DoReMi project.

PubMed

Domienik, J; Farah, J; Struelens, L

2016-12-01

The first validation results of the two approaches developed in the ELDO project for retrospective assessment of eye lens doses for interventional cardiologists (ICs) are presented in this paper. The first approach (a) is based on both the readings from the routine whole body dosimeter worn above the lead apron and procedure-dependent conversion coefficients, while the second approach (b) is based on detailed information related to the occupational exposure history of the ICs declared in a questionnaire and eye lens dose records obtained from the relevant literature. The latter approach makes use of various published eye lens doses per procedure as well as the appropriate correction factors which account for the use of radiation protective tools designed to protect the eye lens. To validate both methodologies, comprehensive measurements were performed in several Polish clinics among recruited physicians. Two dosimeters measuring whole body and eye lens doses were worn by every physician for at least two months. The estimated cumulative eye lens doses, calculated from both approaches, were then compared against the measured eye lens dose value for every physician separately. Both approaches results in comparable estimates of eye lens doses and tend to overestimate rather than underestimate the eye lens doses. The measured and estimated doses do not differ, on average, by a factor higher than 2.0 in 85% and 62% of the cases used to validate approach (a) and (b), respectively. In specific cases, however, the estimated doses differ from the measured ones by as much as a factor of 2.7 and 5.1 for method (a) and (b), respectively. As such, the two approaches can be considered accurate when retrospectively estimating the eye lens doses for ICs and will be of great benefit for ongoing epidemiological studies.

Conceptus radiation dose and risk from chest screen-film radiography.

PubMed

Damilakis, John; Perisinakis, Kostas; Prassopoulos, Panos; Dimovasili, Evangelia; Varveris, Haralambos; Gourtsoyiannis, Nicholas

2003-02-01

The objectives of the present study were to (a) estimate the conceptus radiation dose and risks for pregnant women undergoing posteroanterior and anteroposterior (AP) chest radiographs, (b) study the conceptus dose as a function of chest thickness of the patient undergoing chest radiograph, and (c) investigate the possibility of a conceptus to receive a dose of more than 10 mGy, the level above which specific measurements of conceptus doses may be necessary. Thermoluminescent dosimeters were used for dose measurements in anthropomorphic phantoms simulating pregnancy at the three trimesters of gestation. The effect of chest thickness on conceptus dose and risk was studied by adding slabs of lucite on the anterior and posterior surface of the phantom chest. The conceptus risk for radiation-induced childhood fatal cancer and hereditary effects was calculated based on appropriate risk factors. The average AP chest dimension (d(a)) was estimated for 51 women of childbearing age from chest CT examinations. The value of d(a) was estimated to be 22.3 cm (17.4-27.2 cm). The calculated maximum conceptus dose was 107 x 10(-3) mGy for AP chest radiographs performed during the third trimester of pregnancy with maternal chest thickness of 27.2 cm. This calculation was based on dose data obtained from measurements in the phantoms and d(a) estimated from the patient group. The corresponding average excess of childhood cancer was 10.7 per million patients. The risk for hereditary effects was 1.1 per million births. Radiation dose for a conceptus increases exponentially as chest thickness increases. The conceptus dose at the third trimester is higher than that of the second and first trimesters. The results of the current study suggest that chest radiographs carried out in women at any time during gestation will result in a negligible increase in risk of radiation-induced harmful effects to the unborn child. After a properly performed maternal chest X-ray, there is no need for individual conceptus dose estimations.

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 suggest that optimizing procedure protocols and proper use of protective devices and shields might reduce occupational radiation dose substantially. PMID:22647920

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.

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.

Eye lens dose correlations with personal dose equivalent and patient exposure in paediatric interventional cardiology performed with a fluoroscopic biplane system.

PubMed

Alejo, L; Koren, C; Corredoira, E; Sánchez, F; Bayón, J; Serrada, A; Guibelalde, E

2017-04-01

To analyse the correlations between the eye lens dose estimates performed with dosimeters placed next to the eyes of paediatric interventional cardiologists working with a biplane system, the personal dose equivalent measured on the thorax and the patient dose. The eye lens dose was estimated in terms of H p (0.07) on a monthly basis, placing optically stimulated luminescence dosimeters (OSLDs) on goggles. The H p (0.07) personal dose equivalent was measured over aprons with whole-body OSLDs. Data on patient dose as recorded by the kerma-area product (P KA ) were collected using an automatic dose management system. The 2 paediatric cardiologists working in the facility were involved in the study, and 222 interventions in a 1-year period were evaluated. The ceiling-suspended screen was often disregarded during interventions. The annual eye lens doses estimated on goggles were 4.13±0.93 and 4.98±1.28mSv. Over the aprons, the doses obtained were 10.83±0.99 and 11.97±1.44mSv. The correlation between the goggles and the apron dose was R 2 =0.89, with a ratio of 0.38. The correlation with the patient dose was R 2 =0.40, with a ratio of 1.79μSvGy -1 cm -2 . The dose per procedure obtained over the aprons was 102±16μSv, and on goggles 40±9μSv. The eye lens dose normalized to P KA was 2.21±0.58μSvGy -1 cm -2 . Measurements of personal dose equivalent over the paediatric cardiologist's apron are useful to estimate eye lens dose levels if no radiation protection devices are typically used. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Hanford Environmental Dose Reconstruction Project monthly report

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

McMakin, A.H., Cannon, S.D.; Finch, S.M.

1992-09-01

The objective of the Hanford Environmental Dose Reconstruction MDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The TSP consists of experts in envirorunental pathways. epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering. radiation dosimetry. and cultural anthropology. Included are appointed members representing the states of Oregon, Washington, and Idaho, a representative of Native American tribes, and an individual representing the public. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact onmore » humans (dose estimates): Source Terms; Environmental Transport; Environmental Monitoring Data Demography, Food Consumption, and Agriculture; and Environmental Pathways and Dose Estimates.« less

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.

The linearized multistage model and the future of quantitative risk assessment.

PubMed

Crump, K S

1996-10-01

The linearized multistage (LMS) model has for over 15 years been the default dose-response model used by the U.S. Environmental Protection Agency (USEPA) and other federal and state regulatory agencies in the United States for calculating quantitative estimates of low-dose carcinogenic risks from animal data. The LMS model is in essence a flexible statistical model that can describe both linear and non-linear dose-response patterns, and that produces an upper confidence bound on the linear low-dose slope of the dose-response curve. Unlike its namesake, the Armitage-Doll multistage model, the parameters of the LMS do not correspond to actual physiological phenomena. Thus the LMS is 'biological' only to the extent that the true biological dose response is linear at low dose and that low-dose slope is reflected in the experimental data. If the true dose response is non-linear the LMS upper bound may overestimate the true risk by many orders of magnitude. However, competing low-dose extrapolation models, including those derived from 'biologically-based models' that are capable of incorporating additional biological information, have not shown evidence to date of being able to produce quantitative estimates of low-dose risks that are any more accurate than those obtained from the LMS model. Further, even if these attempts were successful, the extent to which more accurate estimates of low-dose risks in a test animal species would translate into improved estimates of human risk is questionable. Thus, it does not appear possible at present to develop a quantitative approach that would be generally applicable and that would offer significant improvements upon the crude bounding estimates of the type provided by the LMS model. Draft USEPA guidelines for cancer risk assessment incorporate an approach similar to the LMS for carcinogens having a linear mode of action. However, under these guidelines quantitative estimates of low-dose risks would not be developed for carcinogens having a non-linear mode of action; instead dose-response modelling would be used in the experimental range to calculate an LED10* (a statistical lower bound on the dose corresponding to a 10% increase in risk), and safety factors would be applied to the LED10* to determine acceptable exposure levels for humans. This approach is very similar to the one presently used by USEPA for non-carcinogens. Rather than using one approach for carcinogens believed to have a linear mode of action and a different approach for all other health effects, it is suggested herein that it would be more appropriate to use an approach conceptually similar to the 'LED10*-safety factor' approach for all health effects, and not to routinely develop quantitative risk estimates from animal data.

Median infectious dose (ID₅₀) of porcine reproductive and respiratory syndrome virus isolate MN-184 via aerosol exposure.

PubMed

Cutler, Timothy D; Wang, Chong; Hoff, Steven J; Kittawornrat, Apisit; Zimmerman, Jeffrey J

2011-08-05

The median infectious dose (ID(50)) of porcine reproductive and respiratory syndrome (PRRS) virus isolate MN-184 was determined for aerosol exposure. In 7 replicates, 3-week-old pigs (n=58) respired 10l of airborne PRRS virus from a dynamic aerosol toroid (DAT) maintained at -4°C. Thereafter, pigs were housed in isolation and monitored for evidence of infection. Infection occurred at virus concentrations too low to quantify by microinfectivity assays. Therefore, exposure dose was determined using two indirect methods ("calculated" and "theoretical"). "Calculated" virus dose was derived from the concentration of rhodamine B monitored over the exposure sequence. "Theoretical" virus dose was based on the continuous stirred-tank reactor model. The ID(50) estimate was modeled on the proportion of pigs that became infected using the probit and logit link functions for both "calculated" and "theoretical" exposure doses. Based on "calculated" doses, the probit and logit ID(50) estimates were 1 × 10(-0.13)TCID(50) and 1 × 10(-0.14)TCID(50), respectively. Based on "theoretical" doses, the probit and logit ID(50) were 1 × 10(0.26)TCID(50) and 1 × 10(0.24)TCID(50), respectively. For each point estimate, the 95% confidence interval included the other three point estimates. The results indicated that MN-184 was far more infectious than PRRS virus isolate VR-2332, the only other PRRS virus isolate for which ID(50) has been estimated for airborne exposure. Since aerosol ID(50) estimates are available for only these two isolates, it is uncertain whether one or both of these isolates represent the normal range of PRRS virus infectivity by this route. Copyright © 2011 Elsevier B.V. All rights reserved.

On-line estimations of delivered radiation doses in three-dimensional conformal radiotherapy treatments of carcinoma uterine cervix patients in linear accelerator

PubMed Central

Putha, Suman Kumar; Saxena, P. U.; Banerjee, S.; Srinivas, Challapalli; Vadhiraja, B. M.; Ravichandran, Ramamoorthy; Joan, Mary; Pai, K. Dinesh

2016-01-01

Transmission of radiation fluence through patient's body has a correlation to the planned target dose. A method to estimate the delivered dose to target volumes was standardized using a beam level 0.6 cc ionization chamber (IC) positioned at electronic portal imaging device (EPID) plane from the measured transit signal (St) in patients with cancer of uterine cervix treated with three-dimensional conformal radiotherapy (3DCRT). The IC with buildup cap was mounted on linear accelerator EPID frame with fixed source to chamber distance of 146.3 cm, using a locally fabricated mount. Sts were obtained for different water phantom thicknesses and radiation field sizes which were then used to generate a calibration table against calculated midplane doses at isocenter (Diso,TPS), derived from the treatment planning system. A code was developed using MATLAB software which was used to estimate the in vivo dose at isocenter (Diso,Transit) from the measured Sts. A locally fabricated pelvic phantom validated the estimations of Diso,Transit before implementing this method on actual patients. On-line dose estimations were made (3 times during treatment for each patient) in 24 patients. The Diso,Transit agreement with Diso,TPS in phantom was within 1.7% and the mean percentage deviation with standard deviation is −1.37% ±2.03% (n = 72) observed in patients. Estimated in vivo dose at isocenter with this method provides a good agreement with planned ones which can be implemented as part of quality assurance in pelvic sites treated with simple techniques, for example, 3DCRT where there is a need for documentation of planned dose delivery. PMID:28144114

On-line estimations of delivered radiation doses in three-dimensional conformal radiotherapy treatments of carcinoma uterine cervix patients in linear accelerator.

PubMed

Putha, Suman Kumar; Saxena, P U; Banerjee, S; Srinivas, Challapalli; Vadhiraja, B M; Ravichandran, Ramamoorthy; Joan, Mary; Pai, K Dinesh

2016-01-01

Transmission of radiation fluence through patient's body has a correlation to the planned target dose. A method to estimate the delivered dose to target volumes was standardized using a beam level 0.6 cc ionization chamber (IC) positioned at electronic portal imaging device (EPID) plane from the measured transit signal (S t ) in patients with cancer of uterine cervix treated with three-dimensional conformal radiotherapy (3DCRT). The IC with buildup cap was mounted on linear accelerator EPID frame with fixed source to chamber distance of 146.3 cm, using a locally fabricated mount. S t s were obtained for different water phantom thicknesses and radiation field sizes which were then used to generate a calibration table against calculated midplane doses at isocenter (D iso,TPS ), derived from the treatment planning system. A code was developed using MATLAB software which was used to estimate the in vivo dose at isocenter (D iso,Transit ) from the measured S t s. A locally fabricated pelvic phantom validated the estimations of D iso,Transit before implementing this method on actual patients. On-line dose estimations were made (3 times during treatment for each patient) in 24 patients. The D iso,Transit agreement with D iso,TPS in phantom was within 1.7% and the mean percentage deviation with standard deviation is -1.37% ±2.03% ( n = 72) observed in patients. Estimated in vivo dose at isocenter with this method provides a good agreement with planned ones which can be implemented as part of quality assurance in pelvic sites treated with simple techniques, for example, 3DCRT where there is a need for documentation of planned dose delivery.

Effectiveness of Haemophilus influenzae type b vaccines administered according to various schedules: systematic review and meta-analysis of observational data.

PubMed

Jackson, Charlotte; Mann, Andrea; Mangtani, Punam; Fine, Paul

2013-11-01

Conjugate vaccines against Haemophilus influenzae type b (Hib) are widely used. The full implications of Hib vaccination schedule for vaccine effectiveness (VE) are unclear. We searched the literature for observational studies reporting the effectiveness of conjugate Hib vaccines administered according to different schedules. We summarized dose-specific VE estimates, where appropriate, using random effects meta-analysis. Thirty-one eligible articles (reporting 30 studies conducted in 17 countries) were identified. Meta-analysis of case-control studies using community controls produced VE estimates against Hib meningitis of 55% (95% confidence interval: 2-80%, based on 3 studies), 96% (86-99%, 3 studies) and 96% (86-99%, 4 studies) after 1, 2 and 3 doses of vaccines other than the polyribosyl ribitol phosphate outer membrane protein vaccine. Estimates were similar using hospital controls. VE against invasive Hib disease in case-control studies was estimated as 59% (30-76%, 3 studies) and 97% (87-99%, 3 studies) for 1 and 3 doses (insufficient data were identified to estimate 2-dose VE). Point estimates from 2 studies suggested VE>90% after 1 dose of the polyribosyl ribitol phosphate outer membrane protein vaccine, but meta-analysis was not possible. Using data from 4 cohort studies, 3-dose VE was estimated as 94% (88-97%). There was some evidence that Hib vaccine was less effective when administered with acellular (rather than whole cell) pertussis vaccine. Weak evidence from 2 studies suggested that a booster confers some additional protection following full primary vaccination and may compensate for an incomplete primary series. Observational data suggest that ≥2 doses of Hib vaccine are required for high effectiveness, but do not strongly favor any particular schedule.

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

Dosimetry in MARS spectral CT: TOPAS Monte Carlo simulations and ion chamber measurements.

PubMed

Lu, Gray; Marsh, Steven; Damet, Jerome; Carbonez, Pierre; Laban, John; Bateman, Christopher; Butler, Anthony; Butler, Phil

2017-06-01

Spectral computed tomography (CT) is an up and coming imaging modality which shows great promise in revealing unique diagnostic information. Because this imaging modality is based on X-ray CT, it is of utmost importance to study the radiation dose aspects of its use. This study reports on the implementation and evaluation of a Monte Carlo simulation tool using TOPAS for estimating dose in a pre-clinical spectral CT scanner known as the MARS scanner. Simulated estimates were compared with measurements from an ionization chamber. For a typical MARS scan, TOPAS estimated for a 30 mm diameter cylindrical phantom a CT dose index (CTDI) of 29.7 mGy; CTDI was measured by ion chamber to within 3% of TOPAS estimates. Although further development is required, our investigation of TOPAS for estimating MARS scan dosimetry has shown its potential for further study of spectral scanning protocols and dose to scanned objects.

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.

Estimation of Effective Doses for Radiation Cancer Risks on ISS, Lunar, and Mars Missions with Space Radiation Measurement

NASA Technical Reports Server (NTRS)

Kim, M.Y.; Cucinotta, F.A.

2005-01-01

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. The Phantom Torso Experiment (PTE) of NASA s Operational Radiation Protection Program has provided the actual flight measurements of active and passive dosimeters which were placed throughout the phantom on STS-91 mission for 10 days and on ISS Increment 2 mission. For the PTE, the variation in organ doses, which is resulted by the absorption and the changes in radiation quality with tissue shielding, was considered by measuring doses at many tissue sites and at several critical body organs including brain, colon, heart, stomach, thyroid, and skins. These measurements have been compared with the organ dose calculations obtained from the transport models. Active TEPC measurements of lineal energy spectra at the surface of the PTE also provided the direct comparison of galactic cosmic ray (GCR) or trapped proton dose and dose equivalent. It is shown that orienting the phantom body as actual in ISS is needed for the direct comparison of the transport models to the ISS data. One of the most important observations for organ dose equivalent of effective dose estimates on ISS is the fractional contribution from trapped protons and GCR. We show that for most organs over 80% is from GCR. The improved estimation of effective doses for radiation cancer risks will be made with the resultant tissue weighting factors and the modified codes.

Radiation exposure from consumer products and miscellaneous sources

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

Not Available

1977-01-01

This review of the literature indicates that there is a variety of consumer products and miscellaneous sources of radiation that result in exposure to the U.S. population. A summary of the number of people exposed to each such source, an estimate of the resulting dose equivalents to the exposed population, and an estimate of the average annual population dose equivalent are tabulated. A review of the data in this table shows that the total average annual contribution to the whole-body dose equivalent of the U.S. population from consumer products is less than 5 mrem; about 70 percent of this arisesmore » from the presence of naturally-occurring radionuclides in building materials. Some of the consumer product sources contribute exposure mainly to localized tissues or organs. Such localized estimates include: 0.5 to 1 mrem to the average annual population lung dose equivalent (generalized); 2 rem to the average annual population bronchial epithelial dose equivalent (localized); and 10 to 15 rem to the average annual population basal mucosal dose equivalent (basal mucosa of the gum). Based on these estimates, these sources may be grouped or classified as those that involve many people and the dose equivalent is relative large or those that involve many people but the dose equivalent is relatively small, or the dose equivalent is relatively large but the number of people involved is small.« less

Analysis of current assessments and perspectives of ESR tooth dosimetry for radiation dose reconstruction of the population residing near the Semipalatinsk nuclear test site.

PubMed

Romanyukha, Alex; Schauer, David A; Malikov, Yurii K

2006-02-01

Between 1949 and 1989 the Semipalatinsk nuclear test site (SNTS), an area of 19,000 square km in northeastern Kazakhstan, was the location of over 400 nuclear test explosions with a total explosive energy of 6.6 Mt TNT (trinitrotoluene or trotyl) equivalent. It is estimated that the bulk of the radiation exposure to the population resulted from three tests, conducted in 1949, 1951, and 1953 although estimations of radiation doses received by the local population have varied significantly. Analysis of the published ESR dose reconstruction results for residents of the villages near the SNTS show that they do not correlate well with other methods of dose assessment (e.g. model dose calculation and thermo luminescence dosimetry (TLD) in bricks). The most significant difference in dose estimations was found for the population of Dolon, which was exposed as result of the first Soviet nuclear test in 1949. Published results of ESR measurements in tooth enamel are considerably lower than other dose estimations. Detailed analysis of these results is provided and a possible explanation for this discrepancy and ways to eliminate it are suggested.

Determination of the uncertainties in radiation doses from ingestion of strontium-90

NASA Astrophysics Data System (ADS)

Apostoaei, Andrei Iulian

Quantification of the uncertainties in the internal dosimetry is important because it can impact the outcome of dose reconstruction, risk assessment or epidemiological studies. This research focused on determination of the uncertainties in the dose factors from a single ingestion of 90Sr by adults, and analyzed the changes with age and the effect of gender. The uncertainties in the estimated dose factors are a factor of 6 for the bone surface, 5 for the red bone marrow, 2.5 for bladder and stomach, 2.2 for the small intestine, 2.1 for the upper large intestine and 2.7 for the lower large intestine. For the rest of the organs the uncertainty is a factor of 3. Only four parameters of the biokinetic model showed an age-dependency within the adult age group: the fractional transfers of strontium from plasma to cortical and trabecular bone, and the removal rates from the cortical and trabecular bone, respectively. When age-dependent biokinetic parameters were used, the estimated dose-factors are very close to the dose factors obtained using age-independent kinetics (within 40%). Thus, the dose factors based on age-independent parameters should suffice for most practical purposes. The dose factors and the associated uncertainties were also calculated as a function of age-at-exposure and attained age. These age dependent curves can be used for estimating doses from continuous intakes, or doses delivered over a limited portion of time. In addition to the committed dose, an expected dose is also estimated in this work. The expected dose is calculated using the dose rate weighted by the probability of surviving up to the age when the dose-rate is delivered. For exposure at young ages the expected dose and the committed dose are similar, but the committed dose decreases to zero when exposure occurs close to age 70, while the expected dose has elevated values pass age 70. No gender differences were found for bone surface, for red bone marrow, and the large intestine. The doses to the soft tissues for females are larger by 20% than the doses for males, because of the differences in the whole-body mass between males and females.

Thyroid Consequences of the Fukushima Nuclear Reactor Accident

PubMed Central

Nagataki, Shigenobu

2012-01-01

Background A special report, ‘The Fukushima Accident’, was delivered at the 35th Annual Meeting of the European Thyroid Association in Krakow on September 11, 2011, and this study is the follow-up of the special report. Objectives To present a preliminary review of potential thyroid consequences of the 2011 Fukushima nuclear reactor accident. Methods Numerous new data have been presented in Japanese, and most of them are available on the website from each research institute and/or from each municipality. The review was made using these data from the website. Results When individual radiation doses were expressed as values in more than 99% of residents, radiation doses by behavior survey in evacuation and deliberate evacuation areas were less than 10 mSv in the first 4 months, and internal radiation doses measured by whole body counters were less than 1 mSv/year. Individual thyroid radiation doses were less than 50 mSv (intervention levels) even in evacuation areas. As for health consequences, no one died and no one suffered from acute effects. The thyroid ultrasound examination is in progress and following examination of almost 40,000 children, 35% of them have nodules and/or cysts but no cancers. Conclusions Countermeasures against radiation must consider current individual measured values, although every effort must be taken to reconstruct radiation doses as precisely as possible. At present, the difference of thyroid radiation dose between Chernobyl and Fukushima appears to be due to the strict control of milk started within a week after the accident in Fukushima. Since the iodine-131 plume moved around in wide areas and for a long time, the method of thyroid protection must be reconsidered. PMID:24783014

Missing doses in the life span study of Japanese atomic bomb survivors.

PubMed

Richardson, David B; Wing, Steve; Cole, Stephen R

2013-03-15

The Life Span Study of atomic bomb survivors is an important source of risk estimates used to inform radiation protection and compensation. Interviews with survivors in the 1950s and 1960s provided information needed to estimate radiation doses for survivors proximal to ground zero. Because of a lack of interview or the complexity of shielding, doses are missing for 7,058 of the 68,119 proximal survivors. Recent analyses excluded people with missing doses, and despite the protracted collection of interview information necessary to estimate some survivors' doses, defined start of follow-up as October 1, 1950, for everyone. We describe the prevalence of missing doses and its association with mortality, distance from hypocenter, city, age, and sex. Missing doses were more common among Nagasaki residents than among Hiroshima residents (prevalence ratio = 2.05; 95% confidence interval: 1.96, 2.14), among people who were closer to ground zero than among those who were far from it, among people who were younger at enrollment than among those who were older, and among males than among females (prevalence ratio = 1.22; 95% confidence interval: 1.17, 1.28). Missing dose was associated with all-cancer and leukemia mortality, particularly during the first years of follow-up (all-cancer rate ratio = 2.16, 95% confidence interval: 1.51, 3.08; and leukemia rate ratio = 4.28, 95% confidence interval: 1.72, 10.67). Accounting for missing dose and late entry should reduce bias in estimated dose-mortality associations.

Missing Doses in the Life Span Study of Japanese Atomic Bomb Survivors

PubMed Central

Richardson, David B.; Wing, Steve; Cole, Stephen R.

2013-01-01

The Life Span Study of atomic bomb survivors is an important source of risk estimates used to inform radiation protection and compensation. Interviews with survivors in the 1950s and 1960s provided information needed to estimate radiation doses for survivors proximal to ground zero. Because of a lack of interview or the complexity of shielding, doses are missing for 7,058 of the 68,119 proximal survivors. Recent analyses excluded people with missing doses, and despite the protracted collection of interview information necessary to estimate some survivors' doses, defined start of follow-up as October 1, 1950, for everyone. We describe the prevalence of missing doses and its association with mortality, distance from hypocenter, city, age, and sex. Missing doses were more common among Nagasaki residents than among Hiroshima residents (prevalence ratio = 2.05; 95% confidence interval: 1.96, 2.14), among people who were closer to ground zero than among those who were far from it, among people who were younger at enrollment than among those who were older, and among males than among females (prevalence ratio = 1.22; 95% confidence interval: 1.17, 1.28). Missing dose was associated with all-cancer and leukemia mortality, particularly during the first years of follow-up (all-cancer rate ratio = 2.16, 95% confidence interval: 1.51, 3.08; and leukemia rate ratio = 4.28, 95% confidence interval: 1.72, 10.67). Accounting for missing dose and late entry should reduce bias in estimated dose-mortality associations. PMID:23429722

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 patient organ doses, Monte Carlo simulations were performed by creating voxelized models of each patient, identifying key organs and incorporating tube current values into the simulations to estimate dose to the lungs and breasts (females only) for chest scans and the liver, kidney, and spleen for abdomen/pelvis scans. Organ doses from simulations using the actual tube current values were compared to those using each of the estimated tube current values (actual-topo and sim-topo). When compared to the actual tube current values, the average error for tube current values estimated from the actual topogram (actual-topo) and simulated topogram (sim-topo) was 3.9% and 5.8% respectively. For Monte Carlo simulations of chest CT exams using the actual tube current values and estimated tube current values (based on the actual-topo and sim-topo methods), the average differences for lung and breast doses ranged from 3.4% to 6.6%. For abdomen/pelvis exams, the average differences for liver, kidney, and spleen doses ranged from 4.2% to 5.3%. Strong agreement between organ doses estimated using actual and estimated tube current values provides validation of both methods for estimating tube current values based on data provided in the topogram or simulated from image data. © 2017 American Association of Physicists in Medicine.

Radiation doses for pediatric nuclear medicine studies: comparing the North American consensus guidelines and the pediatric dosage card of the European Association of Nuclear Medicine.

PubMed

Grant, Frederick D; Gelfand, Michael J; Drubach, Laura A; Treves, S Ted; Fahey, Frederic H

2015-04-01

Estimated radiation dose is important for assessing and communicating the risks and benefits of pediatric nuclear medicine studies. Radiation dose depends on the radiopharmaceutical, the administered activity, and patient factors such as age and size. Most radiation dose estimates for pediatric nuclear medicine have not been based on administered activities of radiopharmaceuticals recommended by established practice guidelines. The dosage card of the European Association of Nuclear Medicine (EANM) and the North American consensus guidelines each provide recommendations of administered activities of radiopharmaceuticals in children, but there are substantial differences between these two guidelines. For 12 commonly performed pediatric nuclear medicine studies, two established pediatric radiopharmaceutical administration guidelines were used to calculate updated radiation dose estimates and to compare the radiation exposure resulting from the recommendations of each of the guidelines. Estimated radiation doses were calculated for 12 common procedures in pediatric nuclear medicine using administered activities recommended by the dosage card of the EANM (version 1.5.2008) and the 2010 North American consensus guidelines for radiopharmaceutical administered activities in pediatrics. Based on standard models and nominal age-based weights, radiation dose was estimated for typical patients at ages 1, 5, 10 and 15 years and adult. The resulting effective doses were compared, with differences greater than 20% considered significant. Following either the EANM dosage card or the 2010 North American guidelines, the highest effective doses occur with radiopharmaceuticals labeled with fluorine-18 and iodine-123. In 24% of cases, following the North American consensus guidelines would result in a substantially higher radiation dose. The guidelines of the EANM dosage card would lead to a substantially higher radiation dose in 39% of all cases, and in 62% of cases in which patients were age 5 years or younger. For 12 commonly performed pediatric nuclear medicine studies, updated radiation dose estimates can guide efforts to reduce radiation exposure and provide current information for discussing radiation exposure and risk with referring physicians, patients and families. There can be substantial differences in radiation exposure for the same procedure, depending upon which of these two guidelines is followed. This discordance identifies opportunities for harmonization of the guidelines, which may lead to further reduction in nuclear medicine radiation doses in children.

Gamma-ray and neutron dosimetry by EPR and AMS, using tooth enamel from atomic-bomb survivors: a mini review.

PubMed

Nakamura, Nori; Hirai, Yuko; Kodama, Yoshiaki

2012-03-01

The electron paramagnetic resonance (EPR, or electron spin resonance) method was used to measure CO₂⁻· radicals recorded in tooth enamel by exposure to atomic-bomb gamma rays. The EPR-estimated doses (i.e. ⁶⁰Co gamma-ray equivalent dose) were generally in good correlation with cytogenetic data of the same survivors, whereas plots of EPR-estimated dose or cytogenetically estimated dose against DS02 doses turned out to scatter more widely. Because those survivors whose EPR doses were higher (or lower) than DS02 doses tended to show also higher (or lower) responses for cytogenetic responses, the apparent variation appears primarily due to problems in individual DS02 doses rather than the measurement errors associated with the EPR or cytogenetic technique. A part of the enamel samples were also used for evaluation of neutron doses by measuring ⁴¹Ca/⁴⁰Ca ratios using the accelerator mass spectrometry technique. The results for the measured ratios were on average ~85 % of the calculated ratios by DS02 (but within the 95 % confidence bounds of the simulated results), which lends support to DS02-derived neutron doses to the survivors.

Entrance radiation doses during paediatric cardiac catheterisations performed for diagnosis or the treatment of congenital heart disease.

PubMed

Papadopoulou, D; Yakoumakis, Em; Sandilos, P; Thanopoulos, V; Makri, Tr; Gialousis, G; Houndas, D; Yakoumakis, N; Georgiou, Ev

2005-01-01

The purpose of this study was to estimate the radiation exposure of children, during cardiac catheterisations for the diagnosis or treatment of congenital heart disease. Radiation doses were estimated for 45 children aged from 1 d to 13 y old. Thermoluminescent dosemeters (TLDs) were used to estimate the posterior entrance dose (DP), the lateral entrance dose (DLAT), the thyroid dose and the gonads dose. A dose-area product (DAP) meter was also attached externally to the tube of the angiographic system and gave a direct value in mGy cm2 for each procedure. Posterior and lateral entrance dose values during cardiac catheterisations ranged from 1 to 197 mGy and from 1.1 to 250.3 mGy, respectively. Radiation exposure to the thyroid and the gonads ranged from 0.3 to 8.4 mGy to 0.1 and 0.7 mGy, respectively. Finally, the DAP meter values ranged between 360 and 33,200 mGy cm2. Radiation doses measured in this study are comparable with those reported to previous studies. Moreover, strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs.

Estimation of patient radiation dose from whole body 18F- FDG PET/CT examination in cancer imaging: a preliminary study

NASA Astrophysics Data System (ADS)

Mahmud, M. H.; Nordin, A. J.; Saad, F. F. Ahmad; Fattah Azman, A. Z.

2014-11-01

This study aims to estimate the radiation effective dose resulting from whole body fluorine-18 flourodeoxyglucose Positron Emission Tomography (18F-FDG PET) scanning as compared to conservative Computed Tomography (CT) techniques in evaluating oncology patients. We reviewed 19 oncology patients who underwent 18F-FDG PET/CT at our centre for cancer staging. Internal and external doses were estimated using radioactivity of injected FDG and volume CT Dose Index (CTDIvol), respectively with employment of the published and modified dose coefficients. The median differences of dose among the conservative CT and PET protocols were determined using Kruskal Wallis test with p < 0.05 considered as significant. The median (interquartile range, IQR) effective doses of non-contrasted CT, contrasted CT and PET scanning protocols were 7.50 (9.35) mSv, 9.76 (3.67) mSv and 6.30 (1.20) mSv, respectively, resulting in the total dose of 21.46 (8.58) mSv. Statistically significant difference was observed in the median effective dose between the three protocols (p < 0.01). The effective doses of whole body 18F-FDG PET technique may be effective the lowest amongst the conventional CT imaging techniques.

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.

Mental disorders in current and former heavy ecstasy (MDMA) users.

PubMed

Thomasius, R; Petersen, K U; Zapletalova, P; Wartberg, L; Zeichner, D; Schmoldt, A

2005-09-01

Ecstasy use has often been found to be associated with psychopathology, yet this research has so far been based largely on subjective symptom ratings. To investigate whether ecstasy users suffered from long-term psychopathological consequences. We compared the prevalence of Diagnostic and Statistical Manual version IV (DSM-IV) mental disorders in 30 current and 29 former ecstasy users, 29 polydrug and 30 drug-naive controls. Groups were approximately matched by age, gender and level of education. The current ecstasy users reported a life-time dose of an average of 821 and the former ecstasy users of 768 ecstasy tablets. Ecstasy users did not significantly differ from controls in the prevalence of mental disorders, except those related to substance use. Substance-induced affective, anxiety and cognitive disorders occurred more frequently among ecstasy users than polydrug controls. The life-time prevalence of ecstasy dependence amounted to 73% in the ecstasy user groups. More than half of the former ecstasy users and nearly half of the current ecstasy users met the criteria of substance-induced cognitive disorders at the time of testing. Logistic regression analyses showed the estimated life-time doses of ecstasy to be predictive of cognitive disorders, both current and life-time. The motivation for ecstasy use is not likely to be self-medication of pre-existing depressive or anxiety disorders as these did not occur more frequently in the ecstasy users than in control groups or in the general population. Cognitive disorders still present after over 5 months of ecstasy abstinence may well be functional consequences of serotonergic neurotoxicity of 3,4-methylenedioxymethamphetamine (MDMA).

SU-E-T-561: Monte Carlo-Based Organ Dose Reconstruction Using Pre-Contoured Human Model for Hodgkins Lymphoma Patients Treated by Cobalt-60 External Beam Therapy

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

Jung, J; Pelletier, C; Lee, C

Purpose: Organ doses for the Hodgkin’s lymphoma patients treated with cobalt-60 radiation were estimated using an anthropomorphic model and Monte Carlo modeling. Methods: A cobalt-60 treatment unit modeled in the BEAMnrc Monte Carlo code was used to produce phase space data. The Monte Carlo simulation was verified with percent depth dose measurement in water at various field sizes. Radiation transport through the lung blocks were modeled by adjusting the weights of phase space data. We imported a precontoured adult female hybrid model and generated a treatment plan. The adjusted phase space data and the human model were imported to themore » XVMC Monte Carlo code for dose calculation. The organ mean doses were estimated and dose volume histograms were plotted. Results: The percent depth dose agreement between measurement and calculation in water phantom was within 2% for all field sizes. The mean organ doses of heart, left breast, right breast, and spleen for the selected case were 44.3, 24.1, 14.6 and 3.4 Gy, respectively with the midline prescription dose of 40.0 Gy. Conclusion: Organ doses were estimated for the patient group whose threedimensional images are not available. This development may open the door to more accurate dose reconstruction and estimates of uncertainties in secondary cancer risk for Hodgkin’s lymphoma patients. This work was partially supported by the intramural research program of the National Institutes of Health, National Cancer Institute, Division of Cancer Epidemiology and Genetics.« less

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 asbestos and welding fume, that the absolute level of confounding exposure did not affect the risk estimates, and that weak relationships existed between monitored lifetime cumulative occupational radiation dose and asbestos or welding fume.

A generic biokinetic model for carbon-14 labelled compounds

NASA Astrophysics Data System (ADS)

Manger, Ryan Paul

Carbon-14, a radioactive nuclide, is used in many industrial applications. Due to its wide range of uses in industry, many workers are at risk of accidental internal exposure to 14C. Being a low energy beta emitter, 14C is not a significant external radiation hazard, but the internal consequences posed by 14C are important, especially because of its long half life of 5730 years [46]. The current biokinetic model recommended by the International Commission on Radiological Protection (ICRP) is a conservative estimate of how radiocarbon is treated by the human body. The ICRP generic radiocarbon model consists of a single compartment representing the entire human body. This compartment has a biological half life of 40 days yielding an effective dose coefficient of 5.8x10-10 Sv B q-1 [44, 45, 49, 53, 54]. This overestimates the dose of all radiocarbon compounds that have been studied [96]. An improved model has been developed that includes and alimentary tract, a urinary bladder, CO2 model, and an "Other" compartment used to model systemic tissues. The model can be adapted to replicate any excretion curve and excretion pattern. In addition, the effective dose coefficient produced by the updated model is near the mean effective dose coefficient of carbon compounds that have been considered in this research. The major areas of improvement are: more anatomically significant, a less conservative dose coefficient, and the ability to manipulate the model for known excretion data. Due to the wide variety of carbon compounds, it is suggested that specific biokinetic models be implemented for known radiocarbon substances. If the source of radiocarbon is dietary, then the physiologically based model proposed by Whillans [102] that splits all ingested radiocarbon compounds into carbohydrates, fats, and proteins should be used.

Active transport of cimetidine into human milk.

PubMed

Oo, C Y; Kuhn, R J; Desai, N; McNamara, P J

1995-11-01

Most xenobiotics are transferred from blood into breast milk by passive diffusion. However, an active transport mechanism has been speculated for cimetidine, and the purpose of this study was to characterize cimetidine transfer into human milk. Twelve healthy lactating volunteers received single oral doses of 100, 600, and 1200 mg cimetidine in a randomized, crossover design on 3 different days. Blood and milk specimens were collected and assayed for cimetidine. In vitro measurements, including skim to whole milk concentration ratio, milk pH, and free fractions in serum and milk were used for a diffusion model prediction of milk to serum concentration ratio of cimetidine; the mean milk/serum ratio (+/- SD) was 1.05 +/- 0.18. The observed milk/serum ratio (5.77 +/- 1.24) was 5.5 times higher than the milk/serum ratio predicted by diffusion. The observed milk/serum ratio for the three dosing regimens were not significantly different from one another. Time of peak concentration (tmax) in milk (3.3 +/- 0.7 hours) displayed a delay compared with serum tmax (1.7 +/- 0.6 hours). Oral clearance for 1200 mg cimetidine dose (0.47 +/- 0.11 L/hr/kg) was significantly lower compared with oral clearance values for 100 and 600 mg cimetidine doses (0.59 +/- 0.11 and 0.57 +/- 0.13 L/hr/kg, respectively). The maternal dose of cimetidine ingested by a suckling infant based on body weight was estimated to be 6.7%, which appears to be safe under normal conditions. This study provides the first definitive evidence of an active transport system for drug transfer into human milk, which may have broader consequences for the suckling infant.

Ecdysteroids affect in vivo protein metabolism of the flight muscle of the tobacco hornworm (Manduca sexta)

NASA Technical Reports Server (NTRS)

Tischler, M. E.; Wu, M.; Cook, P.; Hodsden, S.

1990-01-01

Ecdysteroid growth promotion of the dorsolongitudinal flight muscle of Manduca sexta was studied by measuring in vivo protein metabolism using both "flooding-dose" and "non-carrier" techniques. These procedures differ in that the former method includes injection of non-labelled phenylalanine (30 micromoles/insect) together with the [3H]amino acid. Injected radioactivity plateaued in the haemolymph within 7 min. With the flooding-dose method, haemolymph and intramuscular specific radioactivities were similar between 15 min and 2 h. Incorporation of [3H]phenylalanine into muscle protein was linear with either method between 30 and 120 min. Fractional rates (%/12 h) of synthesis with the flooding-dose technique were best measured after 1 h because of the initial delay in radioactivity equilibration. Estimation of body phenylalanine turnover with the non-carrier method showed 24-53%/h which was negligible with the flooding-dose method. Since the two methods yielded similar rates of protein synthesis, the large injection of non-labelled amino acid did not alter the rate of synthesis. Because the flooding-dose technique requires only a single time point measurement, it is the preferred method. The decline and eventual cessation of flight-muscle growth was mostly a consequence of declining protein synthesis though degradation increased between 76-86 h before eclosion and was relatively rapid. This decline in muscle growth could be prevented by treating pupae with 20-hydroxyecdysone (10 micrograms/insect). Protein accretion was promoted by a decline of up to 80% in protein breakdown, which was offset in part by a concurrent though much smaller decrease in protein synthesis. Therefore, ecdysteroids may increase flight-muscle growth by inhibiting proteolysis.

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.

SU-G-IeP3-12: Preliminary Report On the Experience of Patient Radiation Dose Monitoring and Tracking Systems; PEMNET, Radimetrics and DoseWatch

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

Lin, P; Corwin, F; Ghita, M

Purpose: Three patient radiation dose monitoring and tracking (PRDMT) systems have been in operation at this institution for the past 6 months. There are useful information that should be disseminated to those who are considering installation of PRDMT programs. In addition, there are “problems” uncovered in the process of estimating fluoroscopic “peak” skin dose (PSD), especially, for those patients who received interventional angiographic studies and in conjunction with surgical procedures. Methods: Upon exporting the PRDMT data to Microsoft Excel program, the peak skin dose can be estimated by applying various correction factors including; attenuation due to the tabletop and examinationmore » mattress, table height, tabletop translation, backscatter, etc. A procedure was established to screen and divide the PRDMT reported radiation dose and estimated PSD to three different levels of threshold to assess the potential skin injuries, to assist patient follow-up, risk management and provide radiation dosimetry information in case of “Sentinel Event”. Results: The Radiation Dose Structured Report (RDSR) was found to be the prerequisite for the PRDMT systems to work seamlessly. And, the geometrical parameters (gantry and table orientation) displayed by the equipment are not necessarily implemented in the “patient centric” manner which could result in a large error in the PSD estimation. Since, the PRDMT systems obtain their pertinent data from the DICOM tags including the polarity (+ and − signs), the geometrical parameters need to be verified. Conclusion: PRDMT systems provide a more accurate PSD estimation than previously possible as the air-kerma-area dose meter become widely implemented. However, care should be exercised to correctly apply the geometrical parameters in estimating the patient dose. In addition, further refinement is necessary for these software programs to account for all geometrical parameters such as the tabletop translation in the z-direction in particular.« less

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

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

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

Radiation dose rates now and in the future for residents neighboring restricted areas of the Fukushima Daiichi Nuclear Power Plant

PubMed Central

Harada, Kouji H.; Niisoe, Tamon; Imanaka, Mie; Takahashi, Tomoyuki; Amako, Katsumi; Fujii, Yukiko; Kanameishi, Masatoshi; Ohse, Kenji; Nakai, Yasumichi; Nishikawa, Tamami; Saito, Yuuichi; Sakamoto, Hiroko; Ueyama, Keiko; Hisaki, Kumiko; Ohara, Eiji; Inoue, Tokiko; Yamamoto, Kanako; Matsuoka, Yukiyo; Ohata, Hitomi; Toshima, Kazue; Okada, Ayumi; Sato, Hitomi; Kuwamori, Toyomi; Tani, Hiroko; Suzuki, Reiko; Kashikura, Mai; Nezu, Michiko; Miyachi, Yoko; Arai, Fusako; Kuwamori, Masanori; Harada, Sumiko; Ohmori, Akira; Ishikawa, Hirohiko; Koizumi, Akio

2014-01-01

Radiation dose rates were evaluated in three areas neighboring a restricted area within a 20- to 50-km radius of the Fukushima Daiichi Nuclear Power Plant in August–September 2012 and projected to 2022 and 2062. Study participants wore personal dosimeters measuring external dose equivalents, almost entirely from deposited radionuclides (groundshine). External dose rate equivalents owing to the accident averaged 1.03, 2.75, and 1.66 mSv/y in the village of Kawauchi, the Tamano area of Soma, and the Haramachi area of Minamisoma, respectively. Internal dose rates estimated from dietary intake of radiocesium averaged 0.0058, 0.019, and 0.0088 mSv/y in Kawauchi, Tamano, and Haramachi, respectively. Dose rates from inhalation of resuspended radiocesium were lower than 0.001 mSv/y. In 2012, the average annual doses from radiocesium were close to the average background radiation exposure (2 mSv/y) in Japan. Accounting only for the physical decay of radiocesium, mean annual dose rates in 2022 were estimated as 0.31, 0.87, and 0.53 mSv/y in Kawauchi, Tamano, and Haramachi, respectively. The simple and conservative estimates are comparable with variations in the background dose, and unlikely to exceed the ordinary permissible dose rate (1 mSv/y) for the majority of the Fukushima population. Health risk assessment indicates that post-2012 doses will increase lifetime solid cancer, leukemia, and breast cancer incidences by 1.06%, 0.03% and 0.28% respectively, in Tamano. This assessment was derived from short-term observation with uncertainties and did not evaluate the first-year dose and radioiodine exposure. Nevertheless, this estimate provides perspective on the long-term radiation exposure levels in the three regions. PMID:24567380

Uncertainty analysis for absorbed dose from a brain receptor imaging agent

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

Aydogan, B.; Miller, L.F.; Sparks, R.B.

Absorbed dose estimates are known to contain uncertainties. A recent literature search indicates that prior to this study no rigorous investigation of uncertainty associated with absorbed dose has been undertaken. A method of uncertainty analysis for absorbed dose calculations has been developed and implemented for the brain receptor imaging agent {sup 123}I-IPT. The two major sources of uncertainty considered were the uncertainty associated with the determination of residence time and that associated with the determination of the S values. There are many sources of uncertainty in the determination of the S values, but only the inter-patient organ mass variation wasmore » considered in this work. The absorbed dose uncertainties were determined for lung, liver, heart and brain. Ninety-five percent confidence intervals of the organ absorbed dose distributions for each patient and for a seven-patient population group were determined by the ``Latin Hypercube Sampling`` method. For an individual patient, the upper bound of the 95% confidence interval of the absorbed dose was found to be about 2.5 times larger than the estimated mean absorbed dose. For the seven-patient population the upper bound of the 95% confidence interval of the absorbed dose distribution was around 45% more than the estimated population mean. For example, the 95% confidence interval of the population liver dose distribution was found to be between 1.49E+0.7 Gy/MBq and 4.65E+07 Gy/MBq with a mean of 2.52E+07 Gy/MBq. This study concluded that patients in a population receiving {sup 123}I-IPT could receive absorbed doses as much as twice as large as the standard estimated absorbed dose due to these uncertainties.« less

Patient-specific FDG dosimetry for adult males, adult females, and very low birth weight infants

NASA Astrophysics Data System (ADS)

Niven, Erin

Fluorodeoxyglucose is the most commonly used radiopharmaceutical in Positron Emission Tomography, with applications in neurology, cardiology, and oncology. Despite its routine use worldwide, the radiation absorbed dose estimates from FDG have been based primarily on data obtained from two dogs studied in 1977 and 11 adults (most likely males) studied in 1982. In addition, the dose estimates calculated for FDG have been centered on the adult male, with little or no mention of variations in the dose estimates due to sex, age, height, weight, nationality, diet, or pathological condition. Through an extensive investigation into the Medical Internal Radiation Dose schema for calculating absorbed doses, I have developed a simple patient-specific equation; this equation incorporates the parameters necessary for alterations to the mathematical values of the human model to produce an estimate more representative of the individual under consideration. I have used this method to determine the range of absorbed doses to FDG from the collection of a large quantity of biological data obtained in adult males, adult females, and very low birth weight infants. Therefore, a more accurate quantification of the dose to humans from FDG has been completed. My results show that per unit administered activity, the absorbed dose from FDG is higher for infants compared to adults, and the dose for adult women is higher than for adult men. Given an injected activity of approximately 3.7 MBq kg-1, the doses for adult men, adult women, and full-term newborns would be on the order of 5.5, 7.1, and 2.8 mSv, respectively. These absorbed doses are comparable to the doses received from other nuclear medicine procedures.

Radiation monitoring systems as a tool for assessment of accidental releases at the Chernobyl and Fukushima NPPs

NASA Astrophysics Data System (ADS)

Shershakov, Vjacheslav; Bulgakov, Vladimir

2013-04-01

The experience gained during mitigation of the consequences of the accidents at the Chernobyl and Fukushima NPPs has shown that what makes different the decision-making in case of nuclear accidents is that the greatest benefit from decision-making can be achieved in the early phase of an accident. Support to such process can be provided only by a real-time decision-making support system. In case of a nuclear accident the analysis of the situation and decision-making is not feasible without an operational radiation monitoring system, international data exchange and automated data processing, and the use of computerized decision-making support systems. With this in mind, in the framework of different international programs on the Chernobyl-related issues numerous projects were undertaken to study and develop a set of methods, algorithms and programs providing effective support to emergency response decision-making, starting from accident occurrence to decision-making regarding countermeasures to mitigate effects of radioactive contamination of the environment. The presentation focuses results of the analysis of radiation monitoring data and, on this basis, refining or, for many short-lived radionuclides, reconstructing the source term, modeling dispersion of radioactivity in the environment and assessing its impacts. The obtained results allowed adding and refining the existing estimates and in some cases reconstructing doses for the public on the territories contaminated as a result of the Chernobyl accident. The activities were implemented in two stages. In the first stage, several scenarios for dispersion of Chernobyl-related radioactivity were developed. For each scenario cesium-137 dispersion was estimated and these estimates were compared with measurement data. In the second stage, the scenario which showed the best agreement of calculations and measurements was used for modeling the dispersion of iodine-131and other short-lived radionuclides. The described approach was used for assessing the consequences at the Fukushima NPP. These results are also provided in the presentation. References 1. Kelly G.N., Ehrhardt J., Shershakov V.M.. Decision Support for Off-Site Emergency Preparedness in Europe. Radiation Protection Dosimetry, Vol. 64 Nos. 1-2, 1996, pp. 129-142. 2. Ehrhardt J., Shershakov V.M. Real-time on-line decision support systems (RODOS) for off-site emergency management following a nuclear accident. EUR 16533, 1996 3. Kelly G.N., Shershakov V.M. (Editors). Environmental contamination, radiation doses and health consequences after the ?hernobyl accident. Radiation Protection Dosimetry. Special Commemorative Issue.Vol. 64, 1996 4. Shershakov V.M. Computer information technology for support of radiation monitoring problems. OECD Proceedings of an International Workshop «Nuclear Emergency Data Management», Zurich, Switzerland, 1998, pp. 377-388 5. Pitkevich V.A., Duba V.V., Ivanov V.K., Tsyb A.F., Shershakov V.M., Golubenkov A.V., Borodin R.V., V.A., Kosykh V.S. Reconstruction of External Dose to the Inhabitants Living in the Contaminated Territory of Russia by the Results of the Accident at the Chernobyl NPP. Health Phys., Vol. 30, No. 1, pp. 54-68, 1995. 6. Shershakov V., Fesenko S., Kryshev I., Semioshkina T. Decision-Aiding Tools for Remediation Strategies. In: Radioactivity in the Environment, Volume 14, Remediation of Contaminated Environments, 2009, pp 41- 120, Elsevier Ltd.

Determination of a quantitative relationship between hepatic CYP3A5*1/*3 and CYP3A4 expression for use in the prediction of metabolic clearance in virtual populations.

PubMed

Barter, Z E; Perrett, H F; Yeo, K Rowland; Allorge, D; Lennard, M S; Rostami-Hodjegan, A

2010-11-01

The creation of virtual populations allows the estimation of pharmacokinetic parameters, such as metabolic clearance in extreme individuals rather than the 'average human'. Prediction of variability in metabolic clearance within genetically diverse populations relies on understanding the covariation in the expression of enzymes. A number of statistically significant positive correlations have been observed in the hepatic expression of cytochrome P450 drug metabolising enzymes. However, these rarely provided a quantitative description of the relationships which is required in creating virtual populations. Collation of data from 40 human liver microsomal samples in the current study indicated a significant positive relationship between hepatic microsomal CYP3A5*1/*3 and CYP3A4 content. Having developed a model describing the relationship between hepatic CYP3A4 and CYP3A5*1/*3, the Simcyp Population-based Simulator(®) was used to investigate the consequences of either incorporating or ignoring the relationship between the two enzymes on estimates of drug clearance. Simulations indicated that for a compound with greater metabolism by CYP3A5 than CYP3A4, such as tacrolimus, incorporation of the correlation between CYP3A4 and CYP3A5 does have an impact on the prediction of oral clearance. Failure to consider the relationship between CYP3A4 and CYP3A5 when creating the virtual population led to a 32% lower estimate of oral clearance in individuals possessing both the CYP3A5*1/*3 genotype and high basal concentrations of CYP3A4. Potential clinical implications may include an inadequate dose estimation during clinical study design, the consequences of which may include organ rejection in transplant recipients using immunosuppressants such as tacrolimus or toxicity due to elevated concentrations of circulating metabolites. Copyright © 2010 John Wiley & Sons, Ltd.

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...

a Biokinetic Model for CESIUM-137 in the Fetus

NASA Astrophysics Data System (ADS)

Jones, Karen Lynn

1995-01-01

Previously, there was no method to determine the dose to the embryo, fetus, fetal organs or placenta from radionuclides within the embryo, fetus, or placenta. In the past, the dose to the fetus was assumed to be equivalent to the dose to the uterus. Watson estimated specific absorbed fractions from various maternal organs to the uterine contents which included the fetus, placenta, and amniotic fluid and Sikov estimated the absorbed dose to the embryo/fetus after assuming 1 uCi of radioactivity was made available to the maternal blood.^{1,2} However, this method did not allow for the calculation of a dose to individual fetal organs or the placenta. The radiation dose to the embryo or fetus from Cs-137 in the fetus and placenta due to a chronic ingestion by the mother was determined. The fraction of Cs-137 in the maternal plasma crossing the placenta to the fetal plasma was estimated. The absorbed dose from Cs-137 in each modelled fetal organ was estimated. Since there has been more research regarding potassium in the human body, and particularly in the pregnant woman, a biokinetic model for potassium was developed first and used as a basis and confirmation of the cesium model. Available pertinent information in physiology, embryology, biokinetics, and radiation dosimetry was utilized. Due to the rapid growth of the fetus and placenta, the pregnancy was divided into four gestational periods. The numerous physiological changes that occurred during pregnancy were considered and an appropriate biokinetic model was developed for each of the gestational periods. The amount of cesium in the placenta, embryo, and fetus was estimated for each period. The dose to the fetus from cesium deposited in the embryo or fetus and in the placenta was determined for each period using Medical Internal Radiation Dosimetry (MIRD) methodology. An uncertainty analysis was also performed to account for the variability of the parameters in the biokinetic model based on the experimental data. The uncertainty in the dose estimate was calculated by propagation of errors after determining the uncertainty in the fetal and placenta mass estimates and the effective half-life.

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.

Comparison of modeled estimates of inhalation exposure to aerosols during use of consumer spray products.

PubMed

Park, Jihoon; Yoon, Chungsik; Lee, Kiyoung

2018-05-30

In the field of exposure science, various exposure assessment models have been developed to complement experimental measurements; however, few studies have been published on their validity. This study compares the estimated inhaled aerosol doses of several inhalation exposure models to experimental measurements of aerosols released from consumer spray products, and then compares deposited doses within different parts of the human respiratory tract according to deposition models. Exposure models, including the European Center for Ecotoxicology of Chemicals Targeted Risk Assessment (ECETOC TRA), the Consumer Exposure Model (CEM), SprayExpo, ConsExpo Web and ConsExpo Nano, were used to estimate the inhaled dose under various exposure scenarios, and modeled and experimental estimates were compared. The deposited dose in different respiratory regions was estimated using the International Commission on Radiological Protection model and multiple-path particle dosimetry models under the assumption of polydispersed particles. The modeled estimates of the inhaled doses were accurate in the short term, i.e., within 10 min of the initial spraying, with a differences from experimental estimates ranging from 0 to 73% among the models. However, the estimates for long-term exposure, i.e., exposure times of several hours, deviated significantly from the experimental estimates in the absence of ventilation. The differences between the experimental and modeled estimates of particle number and surface area were constant over time under ventilated conditions. ConsExpo Nano, as a nano-scale model, showed stable estimates of short-term exposure, with a difference from the experimental estimates of less than 60% for all metrics. The deposited particle estimates were similar among the deposition models, particularly in the nanoparticle range for the head airway and alveolar regions. In conclusion, the results showed that the inhalation exposure models tested in this study are suitable for estimating short-term aerosol exposure (within half an hour), but not for estimating long-term exposure. Copyright © 2018 Elsevier GmbH. All rights reserved.

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

The information for the present discussion on the uncertainties associated with estimation of radiation risks and probability of disease causation was assembled for the recently published NCRP Report No. 171 on this topic. This memorandum provides a timely overview of the topic, given that quantitative uncertainty analysis is the state of the art in health risk assessment and given its potential importance to developments in radiation protection. Over the past decade the increasing volume of epidemiology data and the supporting radiobiology findings have aided in the reduction of uncertainty in the risk estimates derived. However, it is equally apparent that there remain significant uncertainties related to dose assessment, low dose and low dose-rate extrapolation approaches (e.g. the selection of an appropriate dose and dose-rate effectiveness factor), the biological effectiveness where considerations of the health effects of high-LET and lower-energy low-LET radiations are required and the transfer of risks from a population for which health effects data are available to one for which such data are not available. The impact of radiation on human health has focused in recent years on cancer, although there has been a decided increase in the data for noncancer effects together with more reliable estimates of the risk following radiation exposure, even at relatively low doses (notably for cataracts and cardiovascular disease). New approaches for the estimation of hereditary risk have been developed with the use of human data whenever feasible, although the current estimates of heritable radiation effects still are based on mouse data because of an absence of effects in human studies. Uncertainties associated with estimation of these different types of health effects are discussed in a qualitative and semi-quantitative manner as appropriate. The way forward would seem to require additional epidemiological studies, especially studies of low dose and low dose-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.

Hanford Environmental Dose Reconstruction Project

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

McMakin, A.H.; Cannon, S.D.; Finch, S.M.

1992-07-01

The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The TSP consists of experts in environmental pathways, epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering, radiation dosimetry, and cultural anthropology. Included are appointed technical members representing the states of Oregon, Washington, and Idaho, a representative of Native American tribes, and an individual representing the public. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impactmore » on humans (dose estimates): Source terms, environmental transport, environmental monitoring data, demography, food consumption, and agriculture, and environmental pathways and dose estimates. Progress is discussed.« less

Hanford Environmental Dose Reconstruction Project. Monthly report

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

McMakin, A.H.; Cannon, S.D.; Finch, S.M.

1992-07-01

The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The TSP consists of experts in environmental pathways, epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering, radiation dosimetry, and cultural anthropology. Included are appointed technical members representing the states of Oregon, Washington, and Idaho, a representative of Native American tribes, and an individual representing the public. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impactmore » on humans (dose estimates): Source terms, environmental transport, environmental monitoring data, demography, food consumption, and agriculture, and environmental pathways and dose estimates. Progress is discussed.« less

Calculations of individual doses for Techa River Cohort members exposed to atmospheric radioiodine from Mayak releases.

PubMed

Napier, Bruce A; Eslinger, Paul W; Tolstykh, Evgenia I; Vorobiova, Marina I; Tokareva, Elena E; Akhramenko, Boris N; Krivoschapov, Victor A; Degteva, Marina O

2017-11-01

Time-dependent thyroid doses were reconstructed for over 29,000 Techa River Cohort members living near the Mayak production facilities from 131 I released to the atmosphere for all relevant exposure pathways. The calculational approach uses four general steps: 1) construct estimates of releases of 131 I to the air from production facilities; 2) model the transport of 131 I in the air and subsequent deposition on the ground and vegetation; 3) model the accumulation of 131 I in environmental media; and 4) calculate individualized doses. The dose calculations are implemented in a Monte Carlo framework that produces best estimates and confidence intervals of dose time-histories. Other radionuclide contributors to thyroid dose were evaluated. The 131 I contribution was 75-99% of the thyroid dose. The mean total thyroid dose for cohort members was 193 mGy and the median was 53 mGy. Thyroid doses for about 3% of cohort members were larger than 1 Gy. About 7% of children born in 1940-1950 had doses larger than 1 Gy. The uncertainty in the 131 I dose estimates is low enough for this approach to be used in regional epidemiological studies. Copyright © 2017. Published by Elsevier Ltd.

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.

Dose in x-ray computed tomography

NASA Astrophysics Data System (ADS)

Kalender, Willi A.

2014-02-01

Radiation dose in x-ray computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. This review aims to present an overview of current concepts for both scanner output metrics and for patient dosimetry and will comment on their strengths and weaknesses. Controversial issues such as the appropriateness of the CT dose index (CTDI) are discussed in detail. A review of approaches to patient dose assessment presently in practice, of the dose levels encountered and options for further dose optimization are also given and discussed. Patient dose assessment remains a topic for further improvement and for international consensus. All approaches presently in use are based on Monte Carlo (MC) simulations. Estimates for effective dose are established, but they are crude and not patient-specific; organ dose estimates are rarely available. Patient- and organ-specific dose estimates can be provided with adequate accuracy and independent of CTDI phantom measurements by fast MC simulations. Such information, in particular on 3D dose distributions, is important and helpful in optimization efforts. Dose optimization has been performed very successfully in recent years and even resulted in applications with effective dose values of below 1 mSv. In general, a trend towards lower dose values based on technical innovations has to be acknowledged. Effective dose values are down to clearly below 10 mSv on average, and there are a number of applications such as cardiac and pediatric CT which are performed routinely below 1 mSv on modern equipment.

Browns Ferry Nuclear Plant radiological impact assessment report, January-June 1988

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

Lee, B.E.

1988-01-01

Potential doses to maximum individuals and the population around Browns Ferry are calcuated for each quarter. Measured plant releases for the reporting period are used to estimate these doses. Dispersion of radioactive effluents in the environment is estimated in accordance with the guidance provided and measuring during the period. Using dose calculation methodologies which are described in detail in the Browns Ferry Offsite Dose Calculation Manual, the doses are calculated and used to determine compliance with the dose limits contained in Browns Ferry's Operating License. In this report, the doses resulting from releases are described and compared to quarterly andmore » annual limits established for Browns Ferry.« less

A framework for estimating radiation-related cancer risks in Japan from the 2011 Fukushima nuclear accident.

PubMed

Walsh, L; Zhang, W; Shore, R E; Auvinen, A; Laurier, D; Wakeford, R; Jacob, P; Gent, N; Anspaugh, L R; Schüz, J; Kesminiene, A; van Deventer, E; Tritscher, A; del Rosarion Pérez, M

2014-11-01

We present here a methodology for health risk assessment adopted by the World Health Organization that provides a framework for estimating risks from the Fukushima nuclear accident after the March 11, 2011 Japanese major earthquake and tsunami. Substantial attention has been given to the possible health risks associated with human exposure to radiation from damaged reactors at the Fukushima Daiichi nuclear power station. Cumulative doses were estimated and applied for each post-accident year of life, based on a reference level of exposure during the first year after the earthquake. A lifetime cumulative dose of twice the first year dose was estimated for the primary radionuclide contaminants ((134)Cs and (137)Cs) and are based on Chernobyl data, relative abundances of cesium isotopes, and cleanup efforts. Risks for particularly radiosensitive cancer sites (leukemia, thyroid and breast cancer), as well as the combined risk for all solid cancers were considered. The male and female cumulative risks of cancer incidence attributed to radiation doses from the accident, for those exposed at various ages, were estimated in terms of the lifetime attributable risk (LAR). Calculations of LAR were based on recent Japanese population statistics for cancer incidence and current radiation risk models from the Life Span Study of Japanese A-bomb survivors. Cancer risks over an initial period of 15 years after first exposure were also considered. LAR results were also given as a percentage of the lifetime baseline risk (i.e., the cancer risk in the absence of radiation exposure from the accident). The LAR results were based on either a reference first year dose (10 mGy) or a reference lifetime dose (20 mGy) so that risk assessment may be applied for relocated and non-relocated members of the public, as well as for adult male emergency workers. The results show that the major contribution to LAR from the reference lifetime dose comes from the first year dose. For a dose of 10 mGy in the first year and continuing exposure, the lifetime radiation-related cancer risks based on lifetime dose (which are highest for children under 5 years of age at initial exposure), are small, and much smaller than the lifetime baseline cancer risks. For example, after initial exposure at age 1 year, the lifetime excess radiation risk and baseline risk of all solid cancers in females were estimated to be 0.7 · 10(-2) and 29.0 · 10(-2), respectively. The 15 year risks based on the lifetime reference dose are very small. However, for initial exposure in childhood, the 15 year risks based on the lifetime reference dose are up to 33 and 88% as large as the 15 year baseline risks for leukemia and thyroid cancer, respectively. The results may be scaled to particular dose estimates after consideration of caveats. One caveat is related to the lack of epidemiological evidence defining risks at low doses, because the predicted risks come from cancer risk models fitted to a wide dose range (0-4 Gy), which assume that the solid cancer and leukemia lifetime risks for doses less than about 0.5 Gy and 0.2 Gy, respectively, are proportional to organ/tissue doses: this is unlikely to seriously underestimate risks, but may overestimate risks. This WHO-HRA framework may be used to update the risk estimates, when new population health statistics data, dosimetry information and radiation risk models become available.

Placental transfer of radiopharmaceuticals and dosimetry in pregnancy

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

Russell, J.R.; Stabin, M.G.; Sparks, R.B.

The calculation of radiation dose estimates to the fetus is often important in nuclear medicine. To obtain the best estimates of radiation dose to the fetus, the best biological and physical models should be employed. In this paper, after identification of radiopharmaceuticals often administered to women of childbearing age, the most recent data available on the placental crossover of these radiopharmaceuticals was used (with standard kinetic models describing the maternal distribution and retention and with the best available physical models) to obtain fetal dose estimates for these radiopharmaceuticals were identified as those most commonly administered to women of childbearing years.more » The literature yielded information on placental crossover of 15 radiopharmaceuticals, from animal or human data. Radiation dose estimates are presented in early pregnancy and at 3-, 6-, and 9-months gestation for these radiopharmaceuticals, as well as for many others used in nuclear medicine (the latter considering only maternal organ contributions to fetal dose). 46 refs., 1 fig., 5 tabs.« less

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 of additional shielding is valuable, as this can dramatically affect fetal dose.

Non-Targeted Effects and the Dose Response for Heavy Ion Tumorigenesis

NASA Technical Reports Server (NTRS)

Chappell, Lori J.; Cucinotta, Francis A.

2010-01-01

There is no human epidemiology data available to estimate the heavy ion cancer risks experienced by astronauts in space. Studies of tumor induction in mice are a necessary step to estimate risks to astronauts. Previous experimental data can be better utilized to model dose response for heavy ion tumorigenesis and plan future low dose studies.

The Impact of a One-Dose versus Two-Dose Oral Cholera Vaccine Regimen in Outbreak Settings: A Modeling Study

PubMed Central

Azman, Andrew S.; Luquero, Francisco J.; Ciglenecki, Iza; Grais, Rebecca F.; Sack, David A.; Lessler, Justin

2015-01-01

Background In 2013, a stockpile of oral cholera vaccine (OCV) was created for use in outbreak response, but vaccine availability remains severely limited. Innovative strategies are needed to maximize the health impact and minimize the logistical barriers to using available vaccine. Here we ask under what conditions the use of one dose rather than the internationally licensed two-dose protocol may do both. Methods and Findings Using mathematical models we determined the minimum relative single-dose efficacy (MRSE) at which single-dose reactive campaigns are expected to be as or more effective than two-dose campaigns with the same amount of vaccine. Average one- and two-dose OCV effectiveness was estimated from published literature and compared to the MRSE. Results were applied to recent outbreaks in Haiti, Zimbabwe, and Guinea using stochastic simulations to illustrate the potential impact of one- and two-dose campaigns. At the start of an epidemic, a single dose must be 35%–56% as efficacious as two doses to avert the same number of cases with a fixed amount of vaccine (i.e., MRSE between 35% and 56%). This threshold decreases as vaccination is delayed. Short-term OCV effectiveness is estimated to be 77% (95% CI 57%–88%) for two doses and 44% (95% CI −27% to 76%) for one dose. This results in a one-dose relative efficacy estimate of 57% (interquartile range 13%–88%), which is above conservative MRSE estimates. Using our best estimates of one- and two-dose efficacy, we projected that a single-dose reactive campaign could have prevented 70,584 (95% prediction interval [PI] 55,943–86,205) cases in Zimbabwe, 78,317 (95% PI 57,435–100,150) in Port-au-Prince, Haiti, and 2,826 (95% PI 2,490–3,170) cases in Conakry, Guinea: 1.1 to 1.2 times as many as a two-dose campaign. While extensive sensitivity analyses were performed, our projections of cases averted in past epidemics are based on severely limited single-dose efficacy data and may not fully capture uncertainty due to imperfect surveillance data and uncertainty about the transmission dynamics of cholera in each setting. Conclusions Reactive vaccination campaigns using a single dose of OCV may avert more cases and deaths than a standard two-dose campaign when vaccine supplies are limited, while at the same time reducing logistical complexity. These findings should motivate consideration of the trade-offs between one- and two-dose campaigns in resource-constrained settings, though further field efficacy data are needed and should be a priority in any one-dose campaign. PMID:26305226

A broadly neutralizing human monoclonal antibody is effective against H7N9.

PubMed

Tharakaraman, Kannan; Subramanian, Vidya; Viswanathan, Karthik; Sloan, Susan; Yen, Hui-Ling; Barnard, Dale L; Leung, Y H Connie; Szretter, Kristy J; Koch, Tyree J; Delaney, James C; Babcock, Gregory J; Wogan, Gerald N; Sasisekharan, Ram; Shriver, Zachary

2015-09-01

Emerging strains of influenza represent a significant public health threat with potential pandemic consequences. Of particular concern are the recently emerged H7N9 strains which cause pneumonia with acute respiratory distress syndrome. Estimates are that nearly 80% of hospitalized patients with H7N9 have received intensive care unit support. VIS410, a human antibody, targets a unique conserved epitope on influenza A. We evaluated the efficacy of VIS410 for neutralization of group 2 influenza strains, including H3N2 and H7N9 strains in vitro and in vivo. VIS410, administered at 50 mg/kg, protected DBA mice infected with A/Anhui/2013 (H7N9), resulting in significant survival benefit upon single-dose (-24 h) or double-dose (-12 h, +48 h) administration (P < 0.001). A single dose of VIS410 at 50 mg/kg (-12 h) combined with oseltamivir at 50 mg/kg (-12 h, twice daily for 7 d) in C57BL/6 mice infected with A/Shanghai 2/2013 (H7N9) resulted in significant decreased lung viral load (P = 0.002) and decreased lung cytokine responses for nine of the 11 cytokines measured. Based on these results, we find that VIS410 may be effective either as monotherapy or combined with antivirals in treating H7N9 disease, as well as disease from other influenza strains.

The cross-cut statistic and its sensitivity to bias in observational studies with ordered doses of treatment.

PubMed

Rosenbaum, Paul R

2016-03-01

A common practice with ordered doses of treatment and ordered responses, perhaps recorded in a contingency table with ordered rows and columns, is to cut or remove a cross from the table, leaving the outer corners--that is, the high-versus-low dose, high-versus-low response corners--and from these corners to compute a risk or odds ratio. This little remarked but common practice seems to be motivated by the oldest and most familiar method of sensitivity analysis in observational studies, proposed by Cornfield et al. (1959), which says that to explain a population risk ratio purely as bias from an unobserved binary covariate, the prevalence ratio of the covariate must exceed the risk ratio. Quite often, the largest risk ratio, hence the one least sensitive to bias by this standard, is derived from the corners of the ordered table with the central cross removed. Obviously, the corners use only a portion of the data, so a focus on the corners has consequences for the standard error as well as for bias, but sampling variability was not a consideration in this early and familiar form of sensitivity analysis, where point estimates replaced population parameters. Here, this cross-cut analysis is examined with the aid of design sensitivity and the power of a sensitivity analysis. © 2015, The International Biometric Society.

The effect of uterine motion and uterine margins on target and normal tissue doses in intensity modulated radiation therapy of cervical cancer

NASA Astrophysics Data System (ADS)

Gordon, J. J.; Weiss, E.; Abayomi, O. K.; Siebers, J. V.; Dogan, N.

2011-05-01

In intensity modulated radiation therapy (IMRT) of cervical cancer, uterine motion can be larger than cervix motion, requiring a larger clinical target volume to planning target volume (CTV-to-PTV) margin around the uterine fundus. This work simulates different motion models and margins to estimate the dosimetric consequences. A virtual study used image sets from ten patients. Plans were created with uniform margins of 1 cm (PTVA) and 2.4 cm (PTVC), and a margin tapering from 2.4 cm at the fundus to 1 cm at the cervix (PTVB). Three inter-fraction motion models (MM) were simulated. In MM1, all structures moved with normally distributed rigid body translations. In MM2, CTV motion was progressively magnified as one moved superiorly from the cervix to the fundus. In MM3, both CTV and normal tissue motion were magnified as in MM2, modeling the scenario where normal tissues move into the void left by the mobile uterus. Plans were evaluated using static and percentile DVHs. For a conventional margin (PTVA), quasi-realistic uterine motion (MM3) reduces fundus dose by about 5 Gy and increases normal tissue volumes receiving 30-50 Gy by ~5%. A tapered CTV-to-PTV margin can restore fundus and CTV doses, but will increase normal tissue volumes receiving 30-50 Gy by a further ~5%.

Estimation of effective dose and lifetime attributable risk from multiple head CT scans in ventriculoperitoneal shunted children.

PubMed

Aw-Zoretic, J; Seth, D; Katzman, G; Sammet, S

2014-10-01

The purpose of this review is to determine the averaged effective dose and lifetime attributable risk factor from multiple head computed tomography (CT) dose data on children with ventriculoperitoneal shunts (VPS). A total of 422 paediatric head CT exams were found between October 2008 and January 2011 and retrospectively reviewed. The CT dose data was weighted with the latest IRCP 103 conversion factor to obtain the effective dose per study and the averaged effective dose was calculated. Estimates of the lifetime attributable risk were also calculated from the averaged effective dose using a conversion factor from the latest BEIR VII report. Our study found the highest effective doses in neonates and the lowest effective doses were observed in the 10-18 years age group. We estimated a 0.007% potential increase risk in neonates and 0.001% potential increased risk in teenagers over the base risk. Multiple head CTs in children equates to a slight potential increase risk in lifetime attributable risk over the baseline risk for cancer, slightly higher in neonates relative to teenagers. The potential risks versus clinical benefit must be assessed. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry.

PubMed

Bostani, Maryam; Mueller, Jonathon W; McMillan, Kyle; Cody, Dianna D; Cagnon, Chris H; DeMarco, John J; McNitt-Gray, Michael F

2015-02-01

The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for all exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. The calculated mean percent difference between TLD measurements and Monte Carlo simulations was -4.9% with standard deviation of 8.7% and a range of -22.7% to 5.7%. The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.

Assessing doses to terrestrial wildlife at a radioactive waste disposal site: inter-comparison of modelling approaches.

PubMed

Johansen, M P; Barnett, C L; Beresford, N A; Brown, J E; Černe, M; Howard, B J; Kamboj, S; Keum, D-K; Smodiš, B; Twining, J R; Vandenhove, H; Vives i Batlle, J; Wood, M D; Yu, C

2012-06-15

Radiological doses to terrestrial wildlife were examined in this model inter-comparison study that emphasised factors causing variability in dose estimation. The study participants used varying modelling approaches and information sources to estimate dose rates and tissue concentrations for a range of biota types exposed to soil contamination at a shallow radionuclide waste burial site in Australia. Results indicated that the dominant factor causing variation in dose rate estimates (up to three orders of magnitude on mean total dose rates) was the soil-to-organism transfer of radionuclides that included variation in transfer parameter values as well as transfer calculation methods. Additional variation was associated with other modelling factors including: how participants conceptualised and modelled the exposure configurations (two orders of magnitude); which progeny to include with the parent radionuclide (typically less than one order of magnitude); and dose calculation parameters, including radiation weighting factors and dose conversion coefficients (typically less than one order of magnitude). Probabilistic approaches to model parameterisation were used to encompass and describe variable model parameters and outcomes. The study confirms the need for continued evaluation of the underlying mechanisms governing soil-to-organism transfer of radionuclides to improve estimation of dose rates to terrestrial wildlife. The exposure pathways and configurations available in most current codes are limited when considering instances where organisms access subsurface contamination through rooting, burrowing, or using different localised waste areas as part of their habitual routines. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

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 computer. Conclusions: The simulation results showed that the deterministic method can be effectively used to estimate the absorbed dose in a CTDI phantom. The accuracy of the discrete ordinates method was close to that of a Monte Carlo simulation, and the primary benefit of the discrete ordinates method lies in its rapid computation speed. It is expected that further optimization of this method in routine clinical CT dose estimation will improve its accuracy and speed.« less

The effect of Haemophilus influenzae type B and pneumococcal conjugate vaccines on childhood meningitis mortality: a systematic review.

PubMed

Davis, Stephanie; Feikin, Daniel; Johnson, Hope L

2013-01-01

Two of the most prevalent causes of severe bacterial meningitis in children, Haemophilus influenzae type B (Hib) and Streptococcus pneumoniae, are preventable by existing vaccines increasingly available in developing countries. Our objective was to estimate the dose-specific effect of Hib and pneumococcal conjugate vaccines (PCV) on childhood meningitis mortality in low-income countries for use in the Lives Saved Tool (LiST). We systematically searched and reviewed published vaccine efficacy trials and observational studies reporting the effect of Hib or PCV vaccines on organism-specific meningitis, bacterial meningitis and all-cause meningitis incidence and mortality among children less than five years old in low- and middle-income countries. Data collection and quality assessments were performed using standardized guidelines. For outcomes available across multiple studies (≥ 2) and approximating meningitis mortality, we pooled estimates reporting dose-specific effects using random effects meta-analytic methods, then combined these with meningitis etiology data to determine the preventable fraction of childhood meningitis mortality for inclusion in LiST. We identified 18 studies of Hib conjugate vaccines reporting relevant meningitis morbidity and mortality outcomes (2 randomized controlled trials [RCTs], 16 observational studies) but few provided dose-specific effects. A meta-analysis of four case-control studies examined the dose-specific effect of Hib conjugate vaccines on Hib meningitis morbidity (1 dose: RR=0.64, 95% CI 0.38-1.06; 2 doses: RR=0.09, 95% CI 0.03-0.27; 3 doses: RR=0.06, 95% CI 0.02-0.22), consistent with results from single RCTs. Pooled estimates of two RCTs provided evidence for the effect of three doses of PCV on vaccine-serotype meningitis morbidity (RR=0.16, 95% CI 0.02-1.20). We considered these outcomes of severe disease as proxy estimates for meningitis mortality and combined the estimates of protective effects with meningitis etiology data to provide an estimate of the preventable fraction of childhood meningitis mortality with three doses of Hib (38-43%) and pneumococcal conjugate vaccines (28-35%) for use in LiST. Few RCTs or vaccine effectiveness studies evaluated the dose-specific impact of Hib and PCV vaccines on childhood meningitis mortality, necessitating use of proxy measures to estimate population impact in LiST. Our analysis indicates that approximately three-quarters of meningitis deaths are preventable with existing Hib and PCV vaccines.

A Monte Carlo study of the impact of the choice of rectum volume definition on estimates of equivalent uniform doses and the volume parameter

NASA Astrophysics Data System (ADS)

Kvinnsland, Yngve; Muren, Ludvig Paul; Dahl, Olav

2004-08-01

Calculations of normal tissue complication probability (NTCP) values for the rectum are difficult because it is a hollow, non-rigid, organ. Finding the true cumulative dose distribution for a number of treatment fractions requires a CT scan before each treatment fraction. This is labour intensive, and several surrogate distributions have therefore been suggested, such as dose wall histograms, dose surface histograms and histograms for the solid rectum, with and without margins. In this study, a Monte Carlo method is used to investigate the relationships between the cumulative dose distributions based on all treatment fractions and the above-mentioned histograms that are based on one CT scan only, in terms of equivalent uniform dose. Furthermore, the effect of a specific choice of histogram on estimates of the volume parameter of the probit NTCP model was investigated. It was found that the solid rectum and the rectum wall histograms (without margins) gave equivalent uniform doses with an expected value close to the values calculated from the cumulative dose distributions in the rectum wall. With the number of patients available in this study the standard deviations of the estimates of the volume parameter were large, and it was not possible to decide which volume gave the best estimates of the volume parameter, but there were distinct differences in the mean values of the values obtained.

Dosimetric evaluation of nanotargeted (188)Re-liposome with the MIRDOSE3 and OLINDA/EXM programs.

PubMed

Chang, Chih-Hsien; Chang, Ya-Jen; Lee, Te-Wei; Ting, Gann; Chang, Kwo-Ping

2012-06-01

The OLINDA/EXM computer code was created as a replacement for the widely used MIRDOSE3 code for radiation dosimetry in nuclear medicine. A dosimetric analysis with these codes was performed to evaluate nanoliposomes as carriers of radionuclides ((188)Re-liposomes) in colon carcinoma-bearing mice. Pharmacokinetic data for (188)Re-N, N-bis (2-mercaptoethyl)-N',N'-diethylethylenediamine ((188)Re-BMEDA) and (188)Re-liposome were obtained for estimation of absorbed doses in normal organs. Radiation dose estimates for normal tissues were calculated using the MIRDOSE3 and OLINDA/EXM programs for a colon carcinoma solid tumor mouse model. Mean absorbed doses derived from(188)Re-BMEDA and (188)Re-liposome in normal tissues were generally similar as calculated by MIRDOSE3 and OLINDA/EXM programs. One notable exception to this was red marrow, wherein MIRDOSE3 resulted in higher absorbed doses than OLINDA/EXM (1.53- and 1.60-fold for (188)Re-BMEDA and (188)Re-liposome, respectively). MIRDOSE3 and OLINDA have very similar residence times and organ doses. Bone marrow doses were estimated by designating cortical bone rather than bone marrow as a source organ. The bone marrow doses calculated by MIRDOSE3 are higher than those by OLINDA. If the bone marrow is designated as a source organ, the doses estimated by MIRDOSE3 and OLINDA programs will be very similar.

SU-E-T-769: T-Test Based Prior Error Estimate and Stopping Criterion for Monte Carlo Dose Calculation in Proton Therapy

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

Hong, X; Gao, H; Schuemann, J

2015-06-15

Purpose: The Monte Carlo (MC) method is a gold standard for dose calculation in radiotherapy. However, it is not a priori clear how many particles need to be simulated to achieve a given dose accuracy. Prior error estimate and stopping criterion are not well established for MC. This work aims to fill this gap. Methods: Due to the statistical nature of MC, our approach is based on one-sample t-test. We design the prior error estimate method based on the t-test, and then use this t-test based error estimate for developing a simulation stopping criterion. The three major components are asmore » follows.First, the source particles are randomized in energy, space and angle, so that the dose deposition from a particle to the voxel is independent and identically distributed (i.i.d.).Second, a sample under consideration in the t-test is the mean value of dose deposition to the voxel by sufficiently large number of source particles. Then according to central limit theorem, the sample as the mean value of i.i.d. variables is normally distributed with the expectation equal to the true deposited dose.Third, the t-test is performed with the null hypothesis that the difference between sample expectation (the same as true deposited dose) and on-the-fly calculated mean sample dose from MC is larger than a given error threshold, in addition to which users have the freedom to specify confidence probability and region of interest in the t-test based stopping criterion. Results: The method is validated for proton dose calculation. The difference between the MC Result based on the t-test prior error estimate and the statistical Result by repeating numerous MC simulations is within 1%. Conclusion: The t-test based prior error estimate and stopping criterion are developed for MC and validated for proton dose calculation. Xiang Hong and Hao Gao were partially supported by the NSFC (#11405105), the 973 Program (#2015CB856000) and the Shanghai Pujiang Talent Program (#14PJ1404500)« less

Do fungi need to be included within environmental radiation protection assessment models?

PubMed

Guillén, J; Baeza, A; Beresford, N A; Wood, M D

2017-09-01

Fungi are used as biomonitors of forest ecosystems, having comparatively high uptakes of anthropogenic and naturally occurring radionuclides. However, whilst they are known to accumulate radionuclides they are not typically considered in radiological assessment tools for environmental (non-human biota) assessment. In this paper the total dose rate to fungi is estimated using the ERICA Tool, assuming different fruiting body geometries, a single ellipsoid and more complex geometries considering the different components of the fruit body and their differing radionuclide contents based upon measurement data. Anthropogenic and naturally occurring radionuclide concentrations from the Mediterranean ecosystem (Spain) were used in this assessment. The total estimated weighted dose rate was in the range 0.31-3.4 μGy/h (5 th -95 th percentile), similar to natural exposure rates reported for other wild groups. The total estimated dose was dominated by internal exposure, especially from 226 Ra and 210 Po. Differences in dose rate between complex geometries and a simple ellipsoid model were negligible. Therefore, the simple ellipsoid model is recommended to assess dose rates to fungal fruiting bodies. Fungal mycelium was also modelled assuming a long filament. Using these geometries, assessments for fungal fruiting bodies and mycelium under different scenarios (post-accident, planned release and existing exposure) were conducted, each being based on available monitoring data. The estimated total dose rate in each case was below the ERICA screening benchmark dose, except for the example post-accident existing exposure scenario (the Chernobyl Exclusion Zone) for which a dose rate in excess of 35 μGy/h was estimated for the fruiting body. Estimated mycelium dose rate in this post-accident existing exposure scenario was close to the 400 μGy/h benchmark for plants, although fungi are generally considered to be less radiosensitive than plants. Further research on appropriate mycelium geometries and their radionuclide content is required. Based on the assessments presented in this paper, there is no need to recommend that fungi should be added to the existing assessment tools and frameworks; if required some tools allow a geometry representing fungi to be created and used within a dose assessment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimated dose rates to members of the public from external exposure to patients with 131I thyroid treatment

DOE PAGES

Dewji, S.; Bellamy, M.; Hertel, N.; ...

2015-03-25

The purpose of this study is to estimate dose rates that may result from exposure to patients who had been administered iodine-131 ( 131I) as part of medical therapy were calculated. These effective dose rate estimates were compared with simplified assumptions under United States Nuclear Regulatory Commission Regulatory Guide 8.39, which does not consider body tissue attenuation nor time-dependent redistribution and excretion of the administered 131I. Methods: Dose rates were estimated for members of the public potentially exposed to external irradiation from patients recently treated with 131I. Tissue attenuation and iodine biokinetics were considered in the patient in a largermore » comprehensive effort to improve external dose rate estimates. The external dose rate estimates are based on Monte Carlo simulations using the Phantom with Movable Arms and Legs (PIMAL), previously developed by Oak Ridge National Laboratory and the United States Nuclear Regulatory Commission. PIMAL was employed to model the relative positions of the 131I patient and members of the public in three exposure scenarios: (1) traveling on a bus in a total of six seated or standing permutations, (2) two nursing home cases where a caregiver is seated at 30 cm from the patient’s bedside and a nursing home resident seated 250 cm away from the patient in an adjacent bed, and (3) two hotel cases where the patient and a guest are in adjacent rooms with beds on opposite sides of the common wall, with the patient and guest both in bed and either seated back-to-back or lying head to head. The biokinetic model predictions of the retention and distribution of 131I in the patient assumed a single voiding of urinary bladder contents that occurred during the trip at 2, 4, or 8 h after 131I administration for the public transportation cases, continuous first-order voiding for the nursing home cases, and regular periodic voiding at 4, 8, or 12 h after administration for the hotel room cases. Organ specific activities of 131I in the thyroid, bladder, and combined remaining tissues were calculated as a function of time after administration. Exposures to members of the public were considered for 131I patients with normal thyroid uptake (peak thyroid uptake of ~27% of administered 131I), differentiated thyroid cancer (DTC, 5% uptake), and hyperthyroidism (80% uptake). Results: The scenario with the patient seated behind the member of the public yielded the highest dose rate estimate of seated public transportation exposure cases. The dose rate to the adjacent room guest was highest for the exposure scenario in which the hotel guest and patient are seated by a factor of ~4 for the normal and differentiated thyroid cancer uptake cases and by a factor of ~3 for the hyperthyroid case. Conclusions: It was determined that for all modeled cases, the DTC case yielded the lowest external dose rates, whereas the hyperthyroid case yielded the highest dose rates. In estimating external dose to members of the public from patients with 131I therapy, consideration must be given to (patient- and case-specific) administered 131I activities and duration of exposure for a more complete estimate. The method implemented here included a detailed calculation model, which provides a means to determine dose rate estimates for a range of scenarios. Finally, the method was demonstrated for variations of three scenarios, showing how dose rates are expected to vary with uptake, voiding pattern, and patient location.« less

Estimated dose rates to members of the public from external exposure to patients with 131I thyroid treatment

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

Dewji, S.; Bellamy, M.; Hertel, N.

The purpose of this study is to estimate dose rates that may result from exposure to patients who had been administered iodine-131 ( 131I) as part of medical therapy were calculated. These effective dose rate estimates were compared with simplified assumptions under United States Nuclear Regulatory Commission Regulatory Guide 8.39, which does not consider body tissue attenuation nor time-dependent redistribution and excretion of the administered 131I. Methods: Dose rates were estimated for members of the public potentially exposed to external irradiation from patients recently treated with 131I. Tissue attenuation and iodine biokinetics were considered in the patient in a largermore » comprehensive effort to improve external dose rate estimates. The external dose rate estimates are based on Monte Carlo simulations using the Phantom with Movable Arms and Legs (PIMAL), previously developed by Oak Ridge National Laboratory and the United States Nuclear Regulatory Commission. PIMAL was employed to model the relative positions of the 131I patient and members of the public in three exposure scenarios: (1) traveling on a bus in a total of six seated or standing permutations, (2) two nursing home cases where a caregiver is seated at 30 cm from the patient’s bedside and a nursing home resident seated 250 cm away from the patient in an adjacent bed, and (3) two hotel cases where the patient and a guest are in adjacent rooms with beds on opposite sides of the common wall, with the patient and guest both in bed and either seated back-to-back or lying head to head. The biokinetic model predictions of the retention and distribution of 131I in the patient assumed a single voiding of urinary bladder contents that occurred during the trip at 2, 4, or 8 h after 131I administration for the public transportation cases, continuous first-order voiding for the nursing home cases, and regular periodic voiding at 4, 8, or 12 h after administration for the hotel room cases. Organ specific activities of 131I in the thyroid, bladder, and combined remaining tissues were calculated as a function of time after administration. Exposures to members of the public were considered for 131I patients with normal thyroid uptake (peak thyroid uptake of ~27% of administered 131I), differentiated thyroid cancer (DTC, 5% uptake), and hyperthyroidism (80% uptake). Results: The scenario with the patient seated behind the member of the public yielded the highest dose rate estimate of seated public transportation exposure cases. The dose rate to the adjacent room guest was highest for the exposure scenario in which the hotel guest and patient are seated by a factor of ~4 for the normal and differentiated thyroid cancer uptake cases and by a factor of ~3 for the hyperthyroid case. Conclusions: It was determined that for all modeled cases, the DTC case yielded the lowest external dose rates, whereas the hyperthyroid case yielded the highest dose rates. In estimating external dose to members of the public from patients with 131I therapy, consideration must be given to (patient- and case-specific) administered 131I activities and duration of exposure for a more complete estimate. The method implemented here included a detailed calculation model, which provides a means to determine dose rate estimates for a range of scenarios. Finally, the method was demonstrated for variations of three scenarios, showing how dose rates are expected to vary with uptake, voiding pattern, and patient location.« less

Fetal radiation monitoring and dose minimization during intensity modulated radiation therapy for glioblastoma in pregnancy.

PubMed

Horowitz, David P; Wang, Tony J C; Wuu, Cheng-Shie; Feng, Wenzheng; Drassinower, Daphnie; Lasala, Anita; Pieniazek, Radoslaw; Cheng, Simon; Connolly, Eileen P; Lassman, Andrew B

2014-11-01

We examined the fetal dose from irradiation of glioblastoma during pregnancy using intensity modulated radiation therapy (IMRT), and describe fetal dose minimization using mobile shielding devices. A case report is described of a pregnant woman with glioblastoma who was treated during the third trimester of gestation with 60 Gy of radiation delivered via a 6 MV photon IMRT plan. Fetal dose without shielding was estimated using an anthropomorphic phantom with ion chamber and diode measurements. Clinical fetal dose with shielding was determined with optically stimulated luminescent dosimeters and ion chamber. Clinical target volume (CTV) and planning target volume (PTV) coverage was 100 and 98 % receiving 95 % of the prescription dose, respectively. Normal tissue tolerances were kept below quantitative analysis of normal tissue effects in the clinic (QUANTEC) recommendations. Without shielding, anthropomorphic phantom measurements showed a cumulative fetal dose of 0.024 Gy. In vivo measurements with shielding in place demonstrated a cumulative fetal dose of 0.016 Gy. The fetal dose estimated without shielding was 0.04 % and with shielding was 0.026 % of the target dose. In vivo estimation of dose equivalent received by the fetus was 24.21 mSv. Using modern techniques, brain irradiation can be delivered to pregnant patients in the third trimester with very low measured doses to the fetus, without compromising target coverage or normal tissue dose constraints. Fetal dose can further be reduced with the use of shielding devices, in keeping with the principle of as low as reasonably achievable.

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.

NCICT: a computational solution to estimate organ doses for pediatric and adult patients undergoing CT scans.

PubMed

Lee, Choonsik; Kim, Kwang Pyo; Bolch, Wesley E; Moroz, Brian E; Folio, Les

2015-12-01

We developed computational methods and tools to assess organ doses for pediatric and adult patients undergoing computed tomography (CT) examinations. We used the International Commission on Radiological Protection (ICRP) reference pediatric and adult phantoms combined with the Monte Carlo simulation of a reference CT scanner to establish comprehensive organ dose coefficients (DC), organ absorbed dose per unit volumetric CT Dose Index (CTDIvol) (mGy/mGy). We also developed methods to estimate organ doses with tube current modulation techniques and size specific dose estimates. A graphical user interface was designed to obtain user input of patient- and scan-specific parameters, and to calculate and display organ doses. A batch calculation routine was also integrated into the program to automatically calculate organ doses for a large number of patients. We entitled the computer program, National Cancer Institute dosimetry system for CT(NCICT). We compared our dose coefficients with those from CT-Expo, and evaluated the performance of our program using CT patient data. Our pediatric DCs show good agreements of organ dose estimation with those from CT-Expo except for thyroid. Our results support that the adult phantom in CT-Expo seems to represent a pediatric individual between 10 and 15 years rather than an adult. The comparison of CTDIvol values between NCICT and dose pages from 10 selected CT scans shows good agreements less than 12% except for two cases (up to 20%). The organ dose comparison between mean and modulated mAs shows that mean mAs-based calculation significantly overestimates dose (up to 2.4-fold) to the organs in close proximity to lungs in chest and chest-abdomen-pelvis scans. Our program provides more realistic anatomy based on the ICRP reference phantoms, higher age resolution, the most up-to-date bone marrow dosimetry, and several convenient features compared to previous tools. The NCICT will be available for research purpose in the near future.

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.

Case Example of Dose Optimization Using Data From Bortezomib Dose-Finding Clinical Trials

PubMed Central

Backenroth, Daniel; Cheung, Ying Kuen Ken; Hershman, Dawn L.; Vulih, Diana; Anderson, Barry; Ivy, Percy; Minasian, Lori

2016-01-01

Purpose The current dose-finding methodology for estimating the maximum tolerated dose of investigational anticancer agents is based on the cytotoxic chemotherapy paradigm. Molecularly targeted agents (MTAs) have different toxicity profiles, which may lead to more long-lasting mild or moderate toxicities as well as to late-onset and cumulative toxicities. Several approved MTAs have been poorly tolerated during long-term administration, leading to postmarketing dose optimization studies to re-evaluate the optimal treatment dose. Using data from completed bortezomib dose-finding trials, we explore its toxicity profile, optimize its dose, and examine the appropriateness of current designs for identifying an optimal dose. Patients and Methods We classified the toxicities captured from 481 patients in 14 bortezomib dose-finding studies conducted through the National Cancer Institute Cancer Therapy Evaluation Program, computed the incidence of late-onset toxicities, and compared the incidence of dose-limiting toxicities (DLTs) among groups of patients receiving different doses of bortezomib. Results A total of 13,008 toxicities were captured: 46% of patients’ first DLTs and 88% of dose reductions or discontinuations of treatment because of toxicity were observed after the first cycle. Moreover, for the approved dose of 1.3 mg/m2, the estimated cumulative incidence of DLT was > 50%, and the estimated cumulative incidence of dose reduction or treatment discontinuation because of toxicity was nearly 40%. Conclusions When considering the entire course of treatment, the approved bortezomib dose exceeds the conventional ceiling DLT rate of 20% to 33%. Retrospective analysis of trial data provides an opportunity for dose optimization of MTAs. Future dose-finding studies of MTAs should take into account late-onset toxicities to ensure that a tolerable dose is identified for future efficacy and comparative trials. PMID:26926682

Case Example of Dose Optimization Using Data From Bortezomib Dose-Finding Clinical Trials.

PubMed

Lee, Shing M; Backenroth, Daniel; Cheung, Ying Kuen Ken; Hershman, Dawn L; Vulih, Diana; Anderson, Barry; Ivy, Percy; Minasian, Lori

2016-04-20

The current dose-finding methodology for estimating the maximum tolerated dose of investigational anticancer agents is based on the cytotoxic chemotherapy paradigm. Molecularly targeted agents (MTAs) have different toxicity profiles, which may lead to more long-lasting mild or moderate toxicities as well as to late-onset and cumulative toxicities. Several approved MTAs have been poorly tolerated during long-term administration, leading to postmarketing dose optimization studies to re-evaluate the optimal treatment dose. Using data from completed bortezomib dose-finding trials, we explore its toxicity profile, optimize its dose, and examine the appropriateness of current designs for identifying an optimal dose. We classified the toxicities captured from 481 patients in 14 bortezomib dose-finding studies conducted through the National Cancer Institute Cancer Therapy Evaluation Program, computed the incidence of late-onset toxicities, and compared the incidence of dose-limiting toxicities (DLTs) among groups of patients receiving different doses of bortezomib. A total of 13,008 toxicities were captured: 46% of patients' first DLTs and 88% of dose reductions or discontinuations of treatment because of toxicity were observed after the first cycle. Moreover, for the approved dose of 1.3 mg/m(2), the estimated cumulative incidence of DLT was > 50%, and the estimated cumulative incidence of dose reduction or treatment discontinuation because of toxicity was nearly 40%. When considering the entire course of treatment, the approved bortezomib dose exceeds the conventional ceiling DLT rate of 20% to 33%. Retrospective analysis of trial data provides an opportunity for dose optimization of MTAs. Future dose-finding studies of MTAs should take into account late-onset toxicities to ensure that a tolerable dose is identified for future efficacy and comparative trials. © 2016 by American Society of Clinical Oncology.

Sci—Fri PM: Dosimetry—04: Radiation out-of-field dose in the treatment of pediatric central nervous system malignancies

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

Taddei, P J; Tannous, J; Nabha, R

Children diagnosed with central nervous system (CNS) malignancies often receive radiotherapy, which can cause radiogenic late effects. In order to identify and reduce the risk of these late effects, we must understand the radiation doses that these children receive. Modern treatment planning systems accurately estimate the absorbed dose within the treatment fields but poorly estimate the dose outside them. The purpose of our study was to measure the out-of-field dose for children receiving localized radiotherapy for CNS cancer and apply an analytical model for estimating dose as a function of distance from the field edge. Radiation fields designed for amore » 12-year-old boy treated in our clinic were applied to an anthropomorphic phantom containing more than 200 thermoluminescent dosimeters. A double-Gaussian function of absorbed dose versus distance from the field edge (i.e., 50% isodose line) was applied, and parameters were allowed to vary and were fit to the model by minimizing the root mean square deviation, RMSD. The fitted model accurately predicted the dose from distances of 4 cm to 50 cm (RMSD = 0.54 cGy/Gy), but the model was not useful in estimating dose for distances less than 4 cm because of wide variation in measured dose, and the double-Gaussian model failed by systematically underestimating the dose beyond 50 cm. In conclusion, the double-Gaussian model may be applicable for points at distances from the field edge between 4 cm and 50 cm, where most children's radiosensitive tissues are located, but for points beyond 50 cm, an improvement should be investigated.« less

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.

Application of computational models to estimate organ radiation dose in rainbow trout from uptake of molybdenum-99 with comparison to iodine-131.

PubMed

Martinez, N E; Johnson, T E; Pinder, J E

2016-01-01

This study compares three anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ radiation dose and dose rates from molybdenum-99 ((99)Mo) uptake in the liver and GI tract. Model comparison and refinement is important to the process of determining accurate doses and dose rates to the whole body and the various organs. Accurate and consistent dosimetry is crucial to the determination of appropriate dose-effect relationships for use in environmental risk assessment. The computational phantoms considered are (1) a geometrically defined model employing anatomically relevant organ size and location, (2) voxel reconstruction of internal anatomy obtained from CT imaging, and (3) a new model utilizing NURBS surfaces to refine the model in (2). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling and combined with empirical models for predicting activity concentration to estimate dose rates and ultimately determine cumulative radiation dose (μGy) to selected organs after several half-lives of (99)Mo. The computational models provided similar results, especially for organs that were both the source and target of radiation (less than 30% difference between all models). Values in the empirical model as well as the 14 day cumulative organ doses determined from (99)Mo uptake are compared to similar models developed previously for (131)I. Finally, consideration is given to treating the GI tract as a solid organ compared to partitioning it into gut contents and GI wall, which resulted in an order of magnitude difference in estimated dose for most organs. Copyright © 2015 Elsevier Ltd. All rights reserved.

An analysis of the equivalent dose calculation for the remainder tissues

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

Zankl, M.; Drexler, G.

1995-09-01

In the 1990 Recommendations of the International Commission on Radiological Protection, the risk-weighted quantity {open_quotes}effective dose equivalent{close_quotes} was replaced by a similar quantity, {open_quotes}effective dose.{close_quotes} Among other alterations, the selection of the organs and tissues contributing to the risk-weighted quantity and their respective weighting factors were changed, including a modified definition of the so-called {open_quotes}remainder.{close_quotes} Close consideration of this latter definition shows that is causes certain ambiguities are unexpected effects which are dealt with in the following. For several geometries of external photon irradiation, the numerical differences of two possible methods of evaluating the remainder dose from the doses tomore » ten single organs, namely as arithmetic mean or as mass weighted average, are assessed. It is shown that deviation from these averaging procedures, as prescribed for these cases where a remainder organ receives a higher dose than an organ with a specified weighting factor, cause discontinuities in the energy dependence of the remainder dose and, consequently, also non-additivity of this quantity. These problems are discussed, and it is shown that, although the numerical consequences for the calculation of the effective dose are small, this unsatisfactory situation needs clarification. One approach might be to abolish some of the ICRP guidance relating to the appropriate tissue weighting factors for the remainder tissues and organs and to make other guidance more precise. 14 refs., 12 figs., 2 tabs.« less

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children

PubMed Central

Balaguru, Duraisamy; Rodriguez, Matthew; Leon, Stephanie; Wagner, Louis K; Beasley, Charles W; Sultzer, Andrew; Numan, Mohammed T

2018-01-01

Objectives: Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot® (Landauer, Glenwood, IL, USA). Background: Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate. Materials and Methods: The nanoDot® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor. Results: A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3–86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values (R2 = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards. Conclusions: Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients. PMID:29440825

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children.

PubMed

Balaguru, Duraisamy; Rodriguez, Matthew; Leon, Stephanie; Wagner, Louis K; Beasley, Charles W; Sultzer, Andrew; Numan, Mohammed T

2018-01-01

Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot ® (Landauer, Glenwood, IL, USA). Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate. The nanoDot ® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot ® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor. A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3-86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values ( R 2 = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards. Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients.

THYROID CANCER STUDY AMONG UKRAINIAN CHILDREN EXPOSED TO RADIATION AFTER THE CHORNOBYL ACCIDENT: IMPROVED ESTIMATES OF THE THYROID DOSES TO THE COHORT MEMBERS

PubMed Central

Likhtarov, Ilya; Kovgan, Lina; Masiuk, Sergii; Talerko, Mykola; Chepurny, Mykola; Ivanova, Olga; Gerasymenko, Valentina; Boyko, Zulfira; Voillequé, Paul; Drozdovitch, Vladimir; Bouville, André

2013-01-01

In collaboration with the Ukrainian Research Center for Radiation Medicine, the U.S. National Cancer Institute initiated a cohort study of children and adolescents exposed to Chornobyl fallout in Ukraine to better understand the long-term health effects of exposure to radioactive iodines. All 13,204 cohort members were subjected to at least one direct thyroid measurement between 30 April and 30 June 1986 and resided at the time of the accident in the northern part of Kyiv, Zhytomyr, or Chernihiv Oblasts, which were the most contaminated territories of Ukraine as a result of radioactive fallout from the Chornobyl accident. Thyroid doses for the cohort members, which had been estimated following the first round of interviews, were re-evaluated following the second round of interviews. The revised thyroid doses range from 0.35 mGy to 42 Gy, with 95 percent of the doses between 1 mGy and 4.2 Gy, an arithmetic mean of 0.65 Gy, and a geometric mean of 0.19 Gy. These means are 70% of the previous estimates, mainly because of the use of country-specific thyroid masses. Many of the individual thyroid dose estimates show substantial differences because of the use of an improved questionnaire for the second round of interviews. Limitations of the current set of thyroid dose estimates are discussed. For the epidemiologic study, the most notable improvement is a revised assessment of the uncertainties, as shared and unshared uncertainties in the parameter values were considered in the calculation of the 1,000 stochastic estimates of thyroid dose for each cohort member. This procedure makes it possible to perform a more realistic risk analysis. PMID:25208014

32 CFR 218.1 - Policies.

Code of Federal Regulations, 2011 CFR

2011-07-01

... radiation environment to which the veteran was exposed and shall include inhaled, ingested and neutron doses. In determining the veteran's dose, initial neutron, initial gamma, residual gamma, and internal... dose, neutron dose, and internal dose. The minimum standards for reporting dose estimates are set forth...

32 CFR 218.1 - Policies.

Code of Federal Regulations, 2010 CFR

2010-07-01

... radiation environment to which the veteran was exposed and shall include inhaled, ingested and neutron doses. In determining the veteran's dose, initial neutron, initial gamma, residual gamma, and internal... dose, neutron dose, and internal dose. The minimum standards for reporting dose estimates are set forth...

32 CFR 218.1 - Policies.

Code of Federal Regulations, 2012 CFR

2012-07-01

... radiation environment to which the veteran was exposed and shall include inhaled, ingested and neutron doses. In determining the veteran's dose, initial neutron, initial gamma, residual gamma, and internal... dose, neutron dose, and internal dose. The minimum standards for reporting dose estimates are set forth...

32 CFR 218.1 - Policies.

Code of Federal Regulations, 2014 CFR

2014-07-01

... radiation environment to which the veteran was exposed and shall include inhaled, ingested and neutron doses. In determining the veteran's dose, initial neutron, initial gamma, residual gamma, and internal... dose, neutron dose, and internal dose. The minimum standards for reporting dose estimates are set forth...

32 CFR 218.1 - Policies.

Code of Federal Regulations, 2013 CFR

2013-07-01

... radiation environment to which the veteran was exposed and shall include inhaled, ingested and neutron doses. In determining the veteran's dose, initial neutron, initial gamma, residual gamma, and internal... dose, neutron dose, and internal dose. The minimum standards for reporting dose estimates are set forth...

Calculations of individual doses for Techa River Cohort members exposed to atmospheric radioiodine from Mayak releases

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

Napier, Bruce A.; Eslinger, Paul W.; Tolstykh, Evgenia I.

Time-dependent thyroid doses were reconstructed for Techa River Cohort members living near the Mayak production facilities from 131I released to the atmosphere for all relevant exposure pathways. The calculational approach uses four general steps: 1) construct estimates of releases of 131I to the air from production facilities; 2) model the transport of 131I in the air and subsequent deposition on the ground and vegetation; 3) model the accumulation of 131I in soil, water, and food products (environmental media); and 4) calculate individual doses by matching appropriate lifestyle and consumption data for the individual to concentrations of 131I in environmental media.more » The dose calculations are implemented in a Monte Carlo framework that produces best estimates and confidence intervals of dose time-histories. The 131I contribution was 75-99% of the thyroid dose. The mean total thyroid dose for cohort members was 193 mGy and the median was 53 mGy. Thyroid doses for about 3% of cohort members were larger than 1 Gy. About 7% of children born in 1940-1950 had doses larger than 1 Gy. The uncertainty in the 131I dose estimates is low enough for this approach to be used in regional epidemiological studies.« less

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

Risk of solid cancer in low dose-rate radiation epidemiological studies and the dose-rate effectiveness factor.

PubMed

Shore, Roy; Walsh, Linda; Azizova, Tamara; Rühm, Werner

2017-10-01

Estimated radiation risks used for radiation protection purposes have been based primarily on the Life Span Study (LSS) of atomic bomb survivors who received brief exposures at high dose rates, many with high doses. Information is needed regarding radiation risks from low dose-rate (LDR) exposures to low linear-energy-transfer (low-LET) radiation. We conducted a meta-analysis of LDR epidemiologic studies that provide dose-response estimates of total solid cancer risk in adulthood in comparison to corresponding LSS risks, in order to estimate a dose rate effectiveness factor (DREF). We identified 22 LDR studies with dose-response risk estimates for solid cancer after minimizing information overlap. For each study, a parallel risk estimate was derived from the LSS risk model using matching values for sex, mean ages at first exposure and attained age, targeted cancer types, and accounting for type of dosimetric assessment. For each LDR study, a ratio of the excess relative risk per Gy (ERR Gy -1 ) to the matching LSS ERR risk estimate (LDR/LSS) was calculated, and a meta-analysis of the risk ratios was conducted. The reciprocal of the resultant risk ratio provided an estimate of the DREF. The meta-analysis showed a LDR/LSS risk ratio of 0.36 (95% confidence interval [CI] 0.14, 0.57) for the 19 studies of solid cancer mortality and 0.33 (95% CI 0.13, 0.54) when three cohorts with only incidence data also were added, implying a DREF with values around 3, but statistically compatible with 2. However, the analyses were highly dominated by the Mayak worker study. When the Mayak study was excluded the LDR/LSS risk ratios increased: 1.12 (95% CI 0.40, 1.84) for mortality and 0.54 (95% CI 0.09, 0.99) for mortality + incidence, implying a lower DREF in the range of 1-2. Meta-analyses that included only cohorts in which the mean dose was <100 mGy yielded a risk ratio of 1.06 (95% CI 0.30, 1.83) for solid cancer mortality and 0.58 (95% CI 0.10, 1.06) for mortality + incidence data. The interpretation of a best estimate for a value of the DREF depends on the appropriateness of including the Mayak study. This study indicates a range of uncertainty in the value of DREF between 1 and about 2 after protracted radiation exposure. The LDR data provide direct evidence regarding risk from exposures at low dose rates as an important complement to the LSS risk estimates used for radiation protection purposes.

SU-G-206-16: Investigation of Dosimetric Consequence Via Cone-Beam CT Based Dose Reconstruction in Hepatocellular Carcinoma Radiotherapy

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

Huang, P; Gang, Y; Qin, S

2016-06-15

Purpose: Many patients with technically unresectable or medically inoperable hepatocellular carcinoma (HCC) had hepatic dosimetric variations as a result of inter-fraction anatomical deformation. This study was conducted to assess the hepatic dosimetric consequences via reconstructing weekly dose in HCC patients receiving three dimensional conformal radiation therapy. Methods: Twenty-one HCC patients with 21 planning CT (pCT) scans and 63 weekly Cone-beam CT (CBCT) scans were enrolled in this investigation. Among them, six patients had been diagnosed of radiation induced liver disease (RILD) and the other fifteen patients had good prognosis after treatment. And each patient had three weekly CBCT before re-planning.more » In reconstructing CBCT-based weekly dose, we registered pCT to CBCT to provide the correct Hounsfield units for the CBCT using gradient-based deformable image registration (DIR), and this modified CBCT (mCBCT) were introduced to enable dose calculation.To obtain the weekly dosimetric consequences, the initial plan beam configurations and dose constraints were re-applied to mCBCT for performing dose calculation, and the mCBCT were extrapolated to 25 fractions. Besides, the manually delineated contour was propagated automatically onto the mCBCT of the new patient by exploiting the deformation vectors field, and the reconstructed weekly dose was mapped back to pCT to understand the dose distribution difference. Also, weekly dosimetric variations were compared with the hepatic radiation tolerance in terms of D50 and Dmean. Results: Among the twenty-one patients, the three weekly D50 increased by 0.7Gy, 5.1Gy and 6.1Gy, respectively, and Dmean increased by 0.9%, 4.7% and 5.5%, respectively. For patients with RILD, the average values of the third weekly D50 and Dmean were both high than hepatic radiation tolerance, while the values of patients without RILD were below. Conclusion: The planned dose on pCT was not a real dose to the liver, and the liver overdose increased the risk of RILD. The author would like to express great thanks to Lei Xing, Daniel S Kapp and Yong Yang in the Stanford University School of Medicine for their valuable suggestions to this work. This work is supported by NSFC(61471226), China Postdoctoral Science Foundation (2015T80739,2014M551949) and research funding from Shandong Province (JQ201516).« less

[BIOLOGICAL EFFECTIVENESS OF FISSION SPECTRUM NEUTRONS AND PROTONS WITH ENERGIES OF 60-126 MEV DURING ACUTE AND PROLONGED IRRADIATION].

PubMed

Shafirkin, A V

2015-01-01

Neutrons of the fission spectrum are characterized by relatively high values of linear energy transfer (LET). Data about their effects on biological objects are used to evaluate the risk of delayed effects of accelerated ions within the same LET range that serve as an experimental model of the nuclei component of galactic cosmic rays (GCR). Additionally, risks of delayed consequences to cosmonaut's health and average lifetime from certain GCR fluxes and secondary neutrons can be also prognosticated. The article deals with comparative analysis of the literature on reduction of average lifespan (ALS) of animals exposed to neutron reactor spectrum, 60-126 MeV protons, and X- and γ-rays in a broad range of radiation intensity and duration. It was shown that a minimal lifespan reduction by 5% occurs due to a brief exposure to neutrons with the absorbed dose of 5 cGy, whereas same lifespan reduction due to hard X- and γ-radiation occurs after absorption of a minimal dose of 100 cGy. Therefore, according to the estimated minimal ALS reduction in mice, neutron effectiveness is 20-fold higher. Biological effectiveness of protons as regards ALS reduction is virtually equal to that of standard types of radiation. Exposure to X- and γ-radiation with decreasing daily doses, and increasing number of fractions and duration gives rise to an apparent trend toward a less dramatic ALS reduction in mice; on the contrary, exposure to neutrons of varying duration had no effect on threshold doses for the specified ALS reductions. Factors of relative biological effectiveness of neutrons reached 40.

Estimation of 1945 to 1957 food consumption

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

Sensitivity of NTCP parameter values against a change of dose calculation algorithm.

PubMed

Brink, Carsten; Berg, Martin; Nielsen, Morten

2007-09-01

Optimization of radiation treatment planning requires estimations of the normal tissue complication probability (NTCP). A number of models exist that estimate NTCP from a calculated dose distribution. Since different dose calculation algorithms use different approximations the dose distributions predicted for a given treatment will in general depend on the algorithm. The purpose of this work is to test whether the optimal NTCP parameter values change significantly when the dose calculation algorithm is changed. The treatment plans for 17 breast cancer patients have retrospectively been recalculated with a collapsed cone algorithm (CC) to compare the NTCP estimates for radiation pneumonitis with those obtained from the clinically used pencil beam algorithm (PB). For the PB calculations the NTCP parameters were taken from previously published values for three different models. For the CC calculations the parameters were fitted to give the same NTCP as for the PB calculations. This paper demonstrates that significant shifts of the NTCP parameter values are observed for three models, comparable in magnitude to the uncertainties of the published parameter values. Thus, it is important to quote the applied dose calculation algorithm when reporting estimates of NTCP parameters in order to ensure correct use of the models.

Sensitivity of NTCP parameter values against a change of dose calculation algorithm

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

Brink, Carsten; Berg, Martin; Nielsen, Morten

2007-09-15

Optimization of radiation treatment planning requires estimations of the normal tissue complication probability (NTCP). A number of models exist that estimate NTCP from a calculated dose distribution. Since different dose calculation algorithms use different approximations the dose distributions predicted for a given treatment will in general depend on the algorithm. The purpose of this work is to test whether the optimal NTCP parameter values change significantly when the dose calculation algorithm is changed. The treatment plans for 17 breast cancer patients have retrospectively been recalculated with a collapsed cone algorithm (CC) to compare the NTCP estimates for radiation pneumonitis withmore » those obtained from the clinically used pencil beam algorithm (PB). For the PB calculations the NTCP parameters were taken from previously published values for three different models. For the CC calculations the parameters were fitted to give the same NTCP as for the PB calculations. This paper demonstrates that significant shifts of the NTCP parameter values are observed for three models, comparable in magnitude to the uncertainties of the published parameter values. Thus, it is important to quote the applied dose calculation algorithm when reporting estimates of NTCP parameters in order to ensure correct use of the models.« less

Celecoxib interferes to a limited extent with aspirin‐mediated inhibition of platelets aggregation

PubMed Central

Ruzov, Mark; Rimon, Gilad; Pikovsky, Oleg

2015-01-01

Aims The aim of the study was to analyze the interaction between celecoxib and low dose aspirin for COX‐1 binding and its consequences on the aspirin‐mediated antiplatelet effects. Methods We investigated ex vivo the interaction between celecoxib and aspirin for COX‐1 binding and measured the resulting antiplatelet effects. We applied mechanism‐based pharmacokinetic−pharmacodynamic (PKPD) modelling to analyze these data and to predict in vivo platelet aggregation for different doses and administration schedules of aspirin and celecoxib. Results The predictions of the PK‐PD model were consistent with results from previous studies that investigated interaction between aspirin and celecoxib. The modelling results indicate that celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. The extent of this interaction can be substantial (up to 15% increase in platelet aggregation by 200 mg day−1 celecoxib when combined with low dose aspirin) during the first days of aspirin administration in patients who are already treated with celecoxib, and it cannot be prevented by separate administration of the interacting drugs. Conclusions At the recommended therapeutic doses, celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. Patients receiving a combination of low dose aspirin and the recommended doses of celecoxib were not identified to have increased risk of cardiovascular and cerebrovascular events due to competition between these drugs for COX‐1 binding. Interaction between low dose aspirin and other COX‐2 inhibitors and its clinical consequences requires further investigation. PMID:26456703

Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

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

Willegaignon, J., E-mail: j.willegaignon@gmail.com; Sapienza, M. T.; Coura-Filho, G. B.

Purpose: The precise determination of organ mass (m{sub th}) and total number of disintegrations within the thyroid gland (A{sup ~}) are essential for thyroid absorbed-dose calculations for radioiodine therapy. Nevertheless, these parameters may vary according to the method employed for their estimation, thus introducing uncertainty in the estimated thyroid absorbed dose and in any dose–response relationship derived using such estimates. In consideration of these points, thyroid absorbed doses for Graves’ disease (GD) treatment planning were calculated using different approaches to estimating the m{sub th} and the A{sup ~}. Methods: Fifty patients were included in the study. Thyroid{sup 131}I uptake measurementsmore » were performed at 2, 6, 24, 48, 96, and 220 h postadministration of a tracer activity in order to estimate the effective half-time (T{sub eff}) of {sup 131}I in the thyroid; the thyroid cumulated activity was then estimated using the T{sub eff} thus determined or, alternatively, calculated by numeric integration of the measured time-activity data. Thyroid mass was estimated by ultrasonography (USG) and scintigraphy (SCTG). Absorbed doses were calculated with the OLINDA/EXM software. The relationships between thyroid absorbed dose and therapy response were evaluated at 3 months and 1 year after therapy. Results: The average ratio (±1 standard deviation) betweenm{sub th} estimated by SCTG and USG was 1.74 (±0.64) and that between A{sup ~} obtained by T{sub eff} and the integration of measured activity in the gland was 1.71 (±0.14). These differences affect the calculated absorbed dose. Overall, therapeutic success, corresponding to induction of durable hypothyroidism or euthyroidism, was achieved in 72% of all patients at 3 months and in 90% at 1 year. A therapeutic success rate of at least 95% was found in the group of patients receiving doses of 200 Gy (p = 0.0483) and 330 Gy (p = 0.0131) when m{sub th} was measured by either USG or SCTG and A{sup ~} was determined by the integration of measured {sup 131}I activity in the thyroid gland and based on T{sub eff}, respectively. No statistically significant relationship was found between therapeutic response and patients’ age, administered {sup 131}I activity (MBq), 24-h thyroid {sup 131}I uptake (%) or T{sub eff} (p ≥ 0.064); nonetheless, a good relationship was found between the therapeutic response and m{sub th} (p ≤ 0.035). Conclusions: According to the results of this study, the most effective thyroid absorbed dose to be targeted in GD therapy should not be based on a fixed dose but rather should be individualized based on the patient'sm{sub th} and A{sup ~}. To achieve a therapeutic success (i.e., durable euthyroidism or hypothyroidism) rate of at least 95%, a thyroid absorbed dose of 200 or 330 Gy is required depending on the methodology used for estimating m{sub th} and A{sup ~}.« less

Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

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

Willegaignon, J., E-mail: j.willegaignon@gmail.com; Sapienza, M. T.; Coura-Filho, G. B.

2014-01-15

Purpose: The precise determination of organ mass (m{sub th}) and total number of disintegrations within the thyroid gland (A{sup ~}) are essential for thyroid absorbed-dose calculations for radioiodine therapy. Nevertheless, these parameters may vary according to the method employed for their estimation, thus introducing uncertainty in the estimated thyroid absorbed dose and in any dose–response relationship derived using such estimates. In consideration of these points, thyroid absorbed doses for Graves’ disease (GD) treatment planning were calculated using different approaches to estimating the m{sub th} and the A{sup ~}. Methods: Fifty patients were included in the study. Thyroid{sup 131}I uptake measurementsmore » were performed at 2, 6, 24, 48, 96, and 220 h postadministration of a tracer activity in order to estimate the effective half-time (T{sub eff}) of {sup 131}I in the thyroid; the thyroid cumulated activity was then estimated using the T{sub eff} thus determined or, alternatively, calculated by numeric integration of the measured time-activity data. Thyroid mass was estimated by ultrasonography (USG) and scintigraphy (SCTG). Absorbed doses were calculated with the OLINDA/EXM software. The relationships between thyroid absorbed dose and therapy response were evaluated at 3 months and 1 year after therapy. Results: The average ratio (±1 standard deviation) betweenm{sub th} estimated by SCTG and USG was 1.74 (±0.64) and that between A{sup ~} obtained by T{sub eff} and the integration of measured activity in the gland was 1.71 (±0.14). These differences affect the calculated absorbed dose. Overall, therapeutic success, corresponding to induction of durable hypothyroidism or euthyroidism, was achieved in 72% of all patients at 3 months and in 90% at 1 year. A therapeutic success rate of at least 95% was found in the group of patients receiving doses of 200 Gy (p = 0.0483) and 330 Gy (p = 0.0131) when m{sub th} was measured by either USG or SCTG and A{sup ~} was determined by the integration of measured {sup 131}I activity in the thyroid gland and based on T{sub eff}, respectively. No statistically significant relationship was found between therapeutic response and patients’ age, administered {sup 131}I activity (MBq), 24-h thyroid {sup 131}I uptake (%) or T{sub eff} (p ≥ 0.064); nonetheless, a good relationship was found between the therapeutic response and m{sub th} (p ≤ 0.035). Conclusions: According to the results of this study, the most effective thyroid absorbed dose to be targeted in GD therapy should not be based on a fixed dose but rather should be individualized based on the patient'sm{sub th} and A{sup ~}. To achieve a therapeutic success (i.e., durable euthyroidism or hypothyroidism) rate of at least 95%, a thyroid absorbed dose of 200 or 330 Gy is required depending on the methodology used for estimating m{sub th} and A{sup ~}.« less

Measuring dose from radiotherapy treatments in the vicinity of a cardiac pacemaker.

PubMed

Peet, Samuel C; Wilks, Rachael; Kairn, Tanya; Crowe, Scott B

2016-12-01

This study investigated the dose absorbed by tissues surrounding artificial cardiac pacemakers during external beam radiotherapy procedures. The usefulness of out-of-field reference data, treatment planning systems, and skin dose measurements to estimate the dose in the vicinity of a pacemaker was also examined. Measurements were performed by installing a pacemaker onto an anthropomorphic phantom, and using radiochromic film and optically stimulated luminescence dosimeters to measure the dose in the vicinity of the device during the delivery of square fields and clinical treatment plans. It was found that the dose delivered in the vicinity of the cardiac device was unevenly distributed both laterally and anteroposteriorly. As the device was moved distally from the square field, the dose dropped exponentially, in line with out-of-field reference data in the literature. Treatment planning systems were found to substantially underestimate the dose for volumetric modulated arc therapy, helical tomotherapy, and 3D conformal treatments. The skin dose was observed to be either greater or lesser than the dose received at the depth of the device, depending on the treatment site, and so care should be if skin dose measurements are to be used to estimate the dose to a pacemaker. Square field reference data may be used as an upper estimate of absorbed dose per monitor unit in the vicinity of a cardiac device for complex treatments involving multiple gantry angles. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A simplified technique for delivering total body irradiation (TBI) with improved dose homogeneity

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

Yao Rui; Bernard, Damian; Turian, Julius

2012-04-15

Purpose: Total body irradiation (TBI) with megavoltage photon beams has been accepted as an important component of management for a number of hematologic malignancies, generally as part of bone marrow conditioning regimens. The purpose of this paper is to present and discuss the authors' TBI technique, which both simplifies the treatment process and improves the treatment quality. Methods: An AP/PA TBI treatment technique to produce uniform dose distributions using sequential collimator reductions during each fraction was implemented, and a sample calculation worksheet is presented. Using this methodology, the dosimetric characteristics of both 6 and 18 MV photon beams, including lungmore » dose under cerrobend blocks was investigated. A method of estimating midplane lung doses based on measured entrance and exit doses was proposed, and the estimated results were compared with measurements. Results: Whole body midplane dose uniformity of {+-}10% was achieved with no more than two collimator-based beam modulations. The proposed model predicted midplane lung doses 5% to 10% higher than the measured doses for 6 and 18 MV beams. The estimated total midplane doses were within {+-}5% of the prescribed midplane dose on average except for the lungs where the doses were 6% to 10% lower than the prescribed dose on average. Conclusions: The proposed TBI technique can achieve dose uniformity within {+-}10%. This technique is easy to implement and does not require complicated dosimetry and/or compensators.« less

Dosimetric verification of lung cancer treatment using the CBCTs estimated from limited-angle on-board projections.

PubMed

Zhang, You; Yin, Fang-Fang; Ren, Lei

2015-08-01

Lung cancer treatment is susceptible to treatment errors caused by interfractional anatomical and respirational variations of the patient. On-board treatment dose verification is especially critical for the lung stereotactic body radiation therapy due to its high fractional dose. This study investigates the feasibility of using cone-beam (CB)CT images estimated by a motion modeling and free-form deformation (MM-FD) technique for on-board dose verification. Both digital and physical phantom studies were performed. Various interfractional variations featuring patient motion pattern change, tumor size change, and tumor average position change were simulated from planning CT to on-board images. The doses calculated on the planning CT (planned doses), the on-board CBCT estimated by MM-FD (MM-FD doses), and the on-board CBCT reconstructed by the conventional Feldkamp-Davis-Kress (FDK) algorithm (FDK doses) were compared to the on-board dose calculated on the "gold-standard" on-board images (gold-standard doses). The absolute deviations of minimum dose (ΔDmin), maximum dose (ΔDmax), and mean dose (ΔDmean), and the absolute deviations of prescription dose coverage (ΔV100%) were evaluated for the planning target volume (PTV). In addition, 4D on-board treatment dose accumulations were performed using 4D-CBCT images estimated by MM-FD in the physical phantom study. The accumulated doses were compared to those measured using optically stimulated luminescence (OSL) detectors and radiochromic films. Compared with the planned doses and the FDK doses, the MM-FD doses matched much better with the gold-standard doses. For the digital phantom study, the average (± standard deviation) ΔDmin, ΔDmax, ΔDmean, and ΔV100% (values normalized by the prescription dose or the total PTV) between the planned and the gold-standard PTV doses were 32.9% (±28.6%), 3.0% (±2.9%), 3.8% (±4.0%), and 15.4% (±12.4%), respectively. The corresponding values of FDK PTV doses were 1.6% (±1.9%), 1.2% (±0.6%), 2.2% (±0.8%), and 17.4% (±15.3%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.3% (±0.2%), 0.9% (±0.6%), 0.6% (±0.4%), and 1.0% (±0.8%), respectively. Similarly, for the physical phantom study, the average ΔDmin, ΔDmax, ΔDmean, and ΔV100% of planned PTV doses were 38.1% (±30.8%), 3.5% (±5.1%), 3.0% (±2.6%), and 8.8% (±8.0%), respectively. The corresponding values of FDK PTV doses were 5.8% (±4.5%), 1.6% (±1.6%), 2.0% (±0.9%), and 9.3% (±10.5%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.4% (±0.8%), 0.8% (±1.0%), 0.5% (±0.4%), and 0.8% (±0.8%), respectively. For the 4D dose accumulation study, the average (± standard deviation) absolute dose deviation (normalized by local doses) between the accumulated doses and the OSL measured doses was 3.3% (±2.7%). The average gamma index (3%/3 mm) between the accumulated doses and the radiochromic film measured doses was 94.5% (±2.5%). MM-FD estimated 4D-CBCT enables accurate on-board dose calculation and accumulation for lung radiation therapy. It can potentially be valuable for treatment quality assessment and adaptive radiation therapy.

Estimation of Organ Absorbed Doses in Patients from 99mTc-diphosphonate Using the Data of MIRDose Software

PubMed Central

Shahbazi-Gahrouei, Daryoush; Cheki, Mohsen; Moslehi, Masoud

2012-01-01

The purpose of this study was to compare estimation of radiation absorbed doses to patients following bone scans with technetium-99m-labeled methylene diphosphonate (MDP) with the estimates given in MIRDose software. In this study, each patient was injected 25 mCi of 99mTc-MDP. Whole-body images from thirty patients were acquired by gamma camera at 10, 60, 90, 180 minutes after 99mTc-MDP injection. To determine the amount of activity in each organ, conjugate view method was applied on images. MIRD equation was then used to estimate absorbed doses in different organs of patients. At the end, absorbed dose values obtained in this study were compared with the data of MIRDose software. The absorbed doses per unit of injected activity (mGy/MBq × 10–4) for liver, kidneys, bladder wall and spleen were 3.86 ± 1.1, 38.73 ± 4.7, 4.16 ± 1.8 and 3.91 ± 1.3, respectively. The results of this study may be useful to estimate the amount of activity that can be administered to the patient and also showed that methods used in the study for absorbed dose calculation is in good agreement with the data of MIRDose software and it is possible to use by a clinician. PMID:23724374

The impact of variation in scaling factors on the estimation of ...

EPA Pesticide Factsheets

Many physiologically based pharmacokinetic (PBPK) models include values for metabolic rate parameters extrapolated from in vitro metabolism studies using scaling factors such as mg of microsomal protein per gram of liver (MPPGL) and liver mass (FVL). Variation in scaling factor values impacts metabolic rate parameter estimates (Vmax) and hence estimates of internal dose used in dose response analysis. The impacts of adult human variation in MPPGL and FVL on estimates of internal dose were assessed using a human PBPK model for BDCM for several internal dose metrics for two exposure scenarios (single 0.25 liter drink of water or 10 minute shower) under plausible (5 micrograms/L) and high level (20 micrograms/L) water concentrations. For both concentrations, all internal dose metrics were changed less than 5% for the showering scenario (combined inhalation and dermal exposure). In contrast, a 27-fold variation in area under the curve for BDCM in venous blood was observed at both oral exposure concentrations, whereas total amount of BDCM metabolized in liver was relatively unchanged. This analysis demonstrates that variability in the scaling factors used for in vitro to in vivo extrapolation (IVIVE) for metabolic rate parameters can have a significant route-dependent impact on estimates of internal dose under environmentally relevant exposure scenarios. This indicates the need to evaluate both uncertainty and variability for scaling factors used for IVIVE. Sca

Multiple Testing, Cumulative Radiation Dose, and Clinical Indications in Patients Undergoing Myocardial Perfusion Imaging

PubMed Central

Einstein, Andrew J.; Weiner, Shepard D.; Bernheim, Adam; Kulon, Michal; Bokhari, Sabahat; Johnson, Lynne L.; Moses, Jeffrey W.; Balter, Stephen

2013-01-01

Context Myocardial perfusion imaging (MPI) is the single medical test with the highest radiation burden to the US population. While many patients undergoing MPI receive repeat MPI testing, or additional procedures involving ionizing radiation, no data are available characterizing their total longitudinal radiation burden and relating radiation burden with reasons for testing. Objective To characterize procedure counts, cumulative estimated effective doses of radiation, and clinical indications, for patients undergoing MPI. Design, Setting, Patients Retrospective cohort study evaluating, for 1097 consecutive patients undergoing index MPI during the first 100 days of 2006 at Columbia University Medical Center, all preceding medical imaging procedures involving ionizing radiation undergone beginning October 1988, and all subsequent procedures through June 2008, at that center. Main Outcome Measures Cumulative estimated effective dose of radiation, number of procedures involving radiation, and indications for testing. Results Patients underwent a median (interquartile range, mean) of 15 (6–32, 23.9) procedures involving radiation exposure; 4 (2–8, 6.5) were high-dose (≥3 mSv, i.e. one year's background radiation), including 1 (1–2, 1.8) MPI studies per patient. 31% of patients received cumulative estimated effective dose from all medical sources >100mSv. Multiple MPIs were performed in 39% of patients, for whom cumulative estimated effective dose was 121 (81–189, 149) mSv. Men and whites had higher cumulative estimated effective doses, and there was a trend towards men being more likely to undergo multiple MPIs than women (40.8% vs. 36.6%, Odds ratio 1.29, 95% confidence interval 0.98–1.69). Over 80% of initial and 90% of repeat MPI exams were performed in patients with known cardiac disease or symptoms consistent with it. Conclusion In this institution, multiple testing with MPI was very common, and in many patients associated with very high cumulative estimated doses of radiation. PMID:21078807

Thermally assisted OSL application for equivalent dose estimation; comparison of multiple equivalent dose values as well as saturation levels determined by luminescence and ESR techniques for a sedimentary sample collected from a fault gouge

NASA Astrophysics Data System (ADS)

Şahiner, Eren; Meriç, Niyazi; Polymeris, George S.

2017-02-01

Equivalent dose estimation (De) constitutes the most important part of either trap-charge dating techniques or dosimetry applications. In the present work, multiple, independent equivalent dose estimation approaches were adopted, using both luminescence and ESR techniques; two different minerals were studied, namely quartz as well as feldspathic polymineral samples. The work is divided into three independent parts, depending on the type of signal employed. Firstly, different De estimation approaches were carried out on both polymineral and contaminated quartz, using single aliquot regenerative dose protocols employing conventional OSL and IRSL signals, acquired at different temperatures. Secondly, ESR equivalent dose estimations using the additive dose procedure both at room temperature and at 90 K were discussed. Lastly, for the first time in the literature, a single aliquot regenerative protocol employing a thermally assisted OSL signal originating from Very Deep Traps was applied for natural minerals. Rejection criteria such as recycling and recovery ratios are also presented. The SAR protocol, whenever applied, provided with compatible De estimations with great accuracy, independent on either the type of mineral or the stimulation temperature. Low temperature ESR signals resulting from Al and Ti centers indicate very large De values due to bleaching in-ability, associated with large uncertainty values. Additionally, dose saturation of different approaches was investigated. For the signal arising from Very Deep Traps in quartz saturation is extended almost by one order of magnitude. It is interesting that most of De values yielded using different luminescence signals agree with each other and ESR Ge center has very large D0 values. The results presented above highly support the argument that the stability and the initial ESR signal of the Ge center is highly sample-dependent, without any instability problems for the cases of quartz resulting from fault gouge.

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.

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

Bogen, K.T.; Conrado, C.L.; Robison, W.L.

A detailed analysis of uncertainty and interindividual variability in estimated doses was conducted for a rehabilitation scenario for Bikini Island at Bikini Atoll, in which the top 40 cm of soil would be removed in the housing and village area, and the rest of the island is treated with potassium fertilizer, prior to an assumed resettlement date of 1999. Predicted doses were considered for the following fallout-related exposure pathways: ingested Cesium-137 and Strontium-90, external gamma exposure, and inhalation and ingestion of Americium-241 + Plutonium-239+240. Two dietary scenarios were considered: (1) imported foods are available (IA), and (2) imported foods aremore » unavailable (only local foods are consumed) (IUA). Corresponding calculations of uncertainty in estimated population-average dose showed that after {approximately}5 y of residence on Bikini, the upper and lower 95% confidence limits with respect to uncertainty in this dose are estimated to be approximately 2-fold higher and lower than its population-average value, respectively (under both IA and IUA assumptions). Corresponding calculations of interindividual variability in the expected value of dose with respect to uncertainty showed that after {approximately}5 y of residence on Bikini, the upper and lower 95% confidence limits with respect to interindividual variability in this dose are estimated to be approximately 2-fold higher and lower than its expected value, respectively (under both IA and IUA assumptions). For reference, the expected values of population-average dose at age 70 were estimated to be 1.6 and 5.2 cSv under the IA and IUA dietary assumptions, respectively. Assuming that 200 Bikini resettlers would be exposed to local foods (under both IA and IUA assumptions), the maximum 1-y dose received by any Bikini resident is most likely to be approximately 2 and 8 mSv under the IA and IUA assumptions, respectively.« less

A gradient of radioactive contamination in Dolon village near the SNTS and comparison of computed dose values with instrumental estimates for the 29 August, 1949 nuclear test.

PubMed

Stepanenko, Valeriy F; Hoshi, Masaharu; Dubasov, Yuriy V; Sakaguchi, Aya; Yamamoto, Masayoshi; Orlov, Mark Y; Bailiff, Ian K; Ivannikov, Alexander I; Skvortsov, Valeriy G; Iaskova, Elena K; Kryukova, Irina G; Zhumadilov, Kassym S; Endo, Satoru; Tanaka, Kenichi; Apsalikov, Kazbek N; Gusev, Boris I

2006-02-01

Spatial distributions of soil contamination by 137Cs (89 sampling points) and 239+240Pu (76 points) near and within Dolon village were analyzed. An essential exponential decrease of contamination was found in Dolon village: the distance of a half reduction in contamination is about 0.87-1.25 km (in a northwest-southeast direction from the supposed centerline of the radioactive trace). This fact is in agreement with the available exposure rate measurements near Dolon (September 1949 archive data): on the basis of a few measurements the pattern of the trace was estimated to comprise a narrow 2 km corridor of maximum exposure rate. To compare computed external doses in air with local dose estimates by retrospective luminescence dosimetry (RLD) the gradient of radioactive soil contamination within the village was accounted for. The computed dose associated with the central axis of the trace was found to be equal to 2260 mGy (calculations based on archive exposure rate data). Local doses near the RLD sampling points (southeast of the village) were calculated to be in the range 466-780 mGy (averaged value: 645+/-70 mGy), which is comparable with RLD data (averaged value 460+/-92 mGy with range 380-618 mGy). A comparison of the computed mean dose in the settlement with dose estimates by ESR tooth enamel dosimetry makes it possible to estimate the "upper level" of the "shielding and behavior" factor in dose reduction for inhabitants of Dolon village which was found to be 0.28+/-0.068.

The Model Averaging for Dichotomous Response Benchmark Dose (MADr-BMD) Tool

EPA Pesticide Factsheets

Providing quantal response models, which are also used in the U.S. EPA benchmark dose software suite, and generates a model-averaged dose response model to generate benchmark dose and benchmark dose lower bound estimates.

Estimating effective dose to pediatric patients undergoing interventional radiology procedures using anthropomorphic phantoms and MOSFET dosimeters.

PubMed

Miksys, Nelson; Gordon, Christopher L; Thomas, Karen; Connolly, Bairbre L

2010-05-01

The purpose of this study was to estimate the effective doses received by pediatric patients during interventional radiology procedures and to present those doses in "look-up tables" standardized according to minute of fluoroscopy and frame of digital subtraction angiography (DSA). Organ doses were measured with metal oxide semiconductor field effect transistor (MOSFET) dosimeters inserted within three anthropomorphic phantoms, representing children at ages 1, 5, and 10 years, at locations corresponding to radiosensitive organs. The phantoms were exposed to mock interventional radiology procedures of the head, chest, and abdomen using posteroanterior and lateral geometries, varying magnification, and fluoroscopy or DSA exposures. Effective doses were calculated from organ doses recorded by the MOSFET dosimeters and are presented in look-up tables according to the different age groups. The largest effective dose burden for fluoroscopy was recorded for posteroanterior and lateral abdominal procedures (0.2-1.1 mSv/min of fluoroscopy), whereas procedures of the head resulted in the lowest effective doses (0.02-0.08 mSv/min of fluoroscopy). DSA exposures of the abdomen imparted higher doses (0.02-0.07 mSv/DSA frame) than did those involving the head and chest. Patient doses during interventional procedures vary significantly depending on the type of procedure. User-friendly look-up tables may provide a helpful tool for health care providers in estimating effective doses for an individual procedure.

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{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}${\\rm CF}_{{\\rm SSDE}}^{{\\rm organ}}$\\end{document} CF SSDE organ were determined for a total of 23 organs in the chest and abdominopelvic region across nine weight subcategories. For organs fully covered by the scan volume, correlation in the chest (average 1.1; range 0.7–1.4) and abdominopelvic region (average 0.9; range 0.7–1.3) was near unity. For organ/tissue that extended beyond the scan volume (i.e., skin, bone marrow, and bone surface), correlation was determined to be poor (average 0.3; range: 0.1–0.4) for both the chest and abdominopelvic regions, respectively. A means to estimate patient organ dose was demonstrated. Calculated patient organ dose, using patient SSDE and \\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 , was compared to previously published pediatric patient doses that accounted for patient size in their dose calculation, and was found to agree in the chest to better than an average of 5% (27.6/26.2) and in the abdominopelvic region to better than 2% (73.4/75.0). Conclusions: For organs fully covered within the scan volume, the average correlation of SSDE and organ absolute dose was found to be better than ±10%. In addition, this study provides a complete list of 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 ) for the chest and abdominopelvic regions, and describes a simple methodology to estimate individual pediatric patient organ dose based on patient SSDE. PMID:24989395

Evaluating biomarkers to model cancer risk post cosmic ray exposure

PubMed Central

Sridhara, Deepa M.; Asaithamby, Aroumougame; Blattnig, Steve R.; Costes, Sylvain V.; Doetsch, Paul W.; Dynan, William S.; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D.; Peterson, Leif E.; Plante, Ianik; Ponomarev, Artem L.; Saha, Janapriya; Snijders, Antoine M.; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M.

2017-01-01

Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing biomarkers and to evaluate the potential for biomarkers to inform models of post exposure cancer risk. Because cellular stress response pathways to space radiation and environmental carcinogens share common nodes, biomarker-driven risk models may be broadly applicable for estimating risks for other carcinogens. PMID:27345199

Evaluating biomarkers to model cancer risk post cosmic ray exposure

NASA Astrophysics Data System (ADS)

Sridharan, Deepa M.; Asaithamby, Aroumougame; Blattnig, Steve R.; Costes, Sylvain V.; Doetsch, Paul W.; Dynan, William S.; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D.; Peterson, Leif E.; Plante, Ianik; Ponomarev, Artem L.; Saha, Janapriya; Snijders, Antoine M.; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M.

2016-06-01

Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing biomarkers and to evaluate the potential for biomarkers to inform models of post exposure cancer risk. Because cellular stress response pathways to space radiation and environmental carcinogens share common nodes, biomarker-driven risk models may be broadly applicable for estimating risks for other carcinogens.

Evaluating biomarkers to model cancer risk post cosmic ray exposure.

PubMed

Sridharan, Deepa M; Asaithamby, Aroumougame; Blattnig, Steve R; Costes, Sylvain V; Doetsch, Paul W; Dynan, William S; Hahnfeldt, Philip; Hlatky, Lynn; Kidane, Yared; Kronenberg, Amy; Naidu, Mamta D; Peterson, Leif E; Plante, Ianik; Ponomarev, Artem L; Saha, Janapriya; Snijders, Antoine M; Srinivasan, Kalayarasan; Tang, Jonathan; Werner, Erica; Pluth, Janice M

2016-06-01

Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing biomarkers and to evaluate the potential for biomarkers to inform models of post exposure cancer risk. Because cellular stress response pathways to space radiation and environmental carcinogens share common nodes, biomarker-driven risk models may be broadly applicable for estimating risks for other carcinogens. Copyright © 2016 The Committee on Space Research (COSPAR). All rights reserved.

Dose rate prediction methodology for remote handled transuranic waste workers at the waste isolation pilot plant.

PubMed

Hayes, Robert

2002-10-01

An approach is described for estimating future dose rates to Waste Isolation Pilot Plant workers processing remote handled transuranic waste. The waste streams will come from the entire U.S. Department of Energy complex and can take on virtually any form found from the processing sequences for defense-related production, radiochemistry, activation and related work. For this reason, the average waste matrix from all generator sites is used to estimate the average radiation fields over the facility lifetime. Innovative new techniques were applied to estimate expected radiation fields. Non-linear curve fitting techniques were used to predict exposure rate profiles from cylindrical sources using closed form equations for lines and disks. This information becomes the basis for Safety Analysis Report dose rate estimates and for present and future ALARA design reviews when attempts are made to reduce worker doses.

Effects of body and organ size on absorbed dose: there is no standard patient. [Radiation dose distribution in patients following radionuclide administration

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

Poston, J.W.

1976-01-01

The problem of estimating the absorbed dose to organs and tissues of the human body due to the presence of a radiopharmaceutical in one or more organs is discussed. Complications are introduced by the fact that the body is not homogeneous and in many cases the organ shapes are not regular. Publications of the MIRD Committee have provided a direct means of estimating the absorbed dose (or absorbed fraction) for a number of radioisotopes. These estimates are based on Monte Carlo calculations for monoenergetic photons distributed uniformly in organs of an adult phantom. The medical physicist finds that his patientmore » does not resemble the adult phantom. In addition, the absorbed fractions for the adult are not reasonable values for the child. This paper examines how these absorbed fraction estimates apply to a nonstandard patient. (auth)« less

Robust optimization based upon statistical theory.

PubMed

Sobotta, B; Söhn, M; Alber, M

2010-08-01

Organ movement is still the biggest challenge in cancer treatment despite advances in online imaging. Due to the resulting geometric uncertainties, the delivered dose cannot be predicted precisely at treatment planning time. Consequently, all associated dose metrics (e.g., EUD and maxDose) are random variables with a patient-specific probability distribution. The method that the authors propose makes these distributions the basis of the optimization and evaluation process. The authors start from a model of motion derived from patient-specific imaging. On a multitude of geometry instances sampled from this model, a dose metric is evaluated. The resulting pdf of this dose metric is termed outcome distribution. The approach optimizes the shape of the outcome distribution based on its mean and variance. This is in contrast to the conventional optimization of a nominal value (e.g., PTV EUD) computed on a single geometry instance. The mean and variance allow for an estimate of the expected treatment outcome along with the residual uncertainty. Besides being applicable to the target, the proposed method also seamlessly includes the organs at risk (OARs). The likelihood that a given value of a metric is reached in the treatment is predicted quantitatively. This information reveals potential hazards that may occur during the course of the treatment, thus helping the expert to find the right balance between the risk of insufficient normal tissue sparing and the risk of insufficient tumor control. By feeding this information to the optimizer, outcome distributions can be obtained where the probability of exceeding a given OAR maximum and that of falling short of a given target goal can be minimized simultaneously. The method is applicable to any source of residual motion uncertainty in treatment delivery. Any model that quantifies organ movement and deformation in terms of probability distributions can be used as basis for the algorithm. Thus, it can generate dose distributions that are robust against interfraction and intrafraction motion alike, effectively removing the need for indiscriminate safety margins.

Assessment of the dose distribution inside a cardiac cath lab using TLD measurements and Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Baptista, M.; Teles, P.; Cardoso, G.; Vaz, P.

2014-11-01

Over the last decade, there was a substantial increase in the number of interventional cardiology procedures worldwide, and the corresponding ionizing radiation doses for both the medical staff and patients became a subject of concern. Interventional procedures in cardiology are normally very complex, resulting in long exposure times. Also, these interventions require the operator to work near the patient and, consequently, close to the primary X-ray beam. Moreover, due to the scattered radiation from the patient and the equipment, the medical staff is also exposed to a non-uniform radiation field that can lead to a significant exposure of sensitive body organs and tissues, such as the eye lens, the thyroid and the extremities. In order to better understand the spatial variation of the dose and dose rate distributions during an interventional cardiology procedure, the dose distribution around a C-arm fluoroscopic system, in operation in a cardiac cath lab at Portuguese Hospital, was estimated using both Monte Carlo (MC) simulations and dosimetric measurements. To model and simulate the cardiac cath lab, including the fluoroscopic equipment used to execute interventional procedures, the state-of-the-art MC radiation transport code MCNPX 2.7.0 was used. Subsequently, Thermo-Luminescent Detector (TLD) measurements were performed, in order to validate and support the simulation results obtained for the cath lab model. The preliminary results presented in this study reveal that the cardiac cath lab model was successfully validated, taking into account the good agreement between MC calculations and TLD measurements. The simulated results for the isodose curves related to the C-arm fluoroscopic system are also consistent with the dosimetric information provided by the equipment manufacturer (Siemens). The adequacy of the implemented computational model used to simulate complex procedures and map dose distributions around the operator and the medical staff is discussed, in view of the optimization principle (and the associated ALARA objective), one of the pillars of the international system of radiological protection.

Modeling the economic and health consequences of managing chronic osteoarthritis pain with opioids in Germany: comparison of extended-release oxycodone and OROS hydromorphone.

PubMed

Ward, Alexandra; Bozkaya, Duygu; Fleischmann, Jochen; Dubois, Dominique; Sabatowski, Rainer; Caro, J Jaime

2007-10-01

The Osmotic controlled-Release Oral delivery System (OROS) hydromorphone ensures continuous release of hydromorphone over 24 hours. It is anticipated that this will facilitate optimal pain relief, improve quality of sleep and compliance. This simulation compared managing chronic osteoarthritis pain with once-daily OROS hydromorphone with an equianalgesic dose of extended-release (ER) oxycodone administered two or three times a day. This discrete event simulation follows patients for a year after initiating opioid treatment. Pairs of identical patients are created; one receives OROS hydromorphone the other ER oxycodone; undergo dose adjustments and after titration can be dissatisfied or satisfied, suffer adverse events, pain recurrence, or discontinue the opioid. Each is assigned an initial sleep problems score, and an improved score from a treatment dependent distribution at the end of titration; these are translated to a utility value. Utilities are assigned pre-treatment, updated until the patient reaches the optimal dose or is non-compliant or dissatisfied. The OROS hydromorphone and ER oxycodone doses are converted to equianalgesic morphine doses using the following ratios: hydromorphone to morphine ratio; 1:5, oxycodone to morphine ratio; 1:2. Sensitivity analyses explored uncertainty in the conversion ratios and other key parameters. Direct medical costs are in 2005 euros. Over 1 year on a mean daily morphine-equivalent dose of 90 mg, 14% were estimated to be dissatisfied with each opioid. OROS hydromorphone was predicted to yield 0.017 additional quality-adjusted life years (QALYs)/patient for a small additional annual cost (E141/patient), yielding an incremental cost-effectiveness ratio (ICER) of E8343/QALY gained. Changing the assumed conversion ratio for oxycodone:morphine to 1:1.5 led to lower net costs of E68 per patient, E3979/QALY, and for hydromorphone to 1:7.5 to savings. Based on these analyses, OROS hydromorphone is expected to yield health benefits at reasonable cost in Germany.

Dosimetric and radiobiological consequences of computed tomography-guided adaptive strategies for intensity modulated radiation therapy of the prostate.

PubMed

Battista, Jerry J; Johnson, Carol; Turnbull, David; Kempe, Jeff; Bzdusek, Karl; Van Dyk, Jacob; Bauman, Glenn

2013-12-01

To examine a range of scenarios for image-guided adaptive radiation therapy of prostate cancer, including different schedules for megavoltage CT imaging, patient repositioning, and dose replanning. We simulated multifraction dose distributions with deformable registration using 35 sets of megavoltage CT scans of 13 patients. We computed cumulative dose-volume histograms, from which tumor control probabilities and normal tissue complication probabilities (NTCPs) for rectum were calculated. Five-field intensity modulated radiation therapy (IMRT) with 18-MV x-rays was planned to achieve an isocentric dose of 76 Gy to the clinical target volume (CTV). The differences between D95, tumor control probability, V70Gy, and NTCP for rectum, for accumulated versus planned dose distributions, were compared for different target volume sizes, margins, and adaptive strategies. The CTV D95 for IMRT treatment plans, averaged over 13 patients, was 75.2 Gy. Using the largest CTV margins (10/7 mm), the D95 values accumulated over 35 fractions were within 2% of the planned value, regardless of the adaptive strategy used. For tighter margins (5 mm), the average D95 values dropped to approximately 73.0 Gy even with frequent repositioning, and daily replanning was necessary to correct this deficit. When personalized margins were applied to an adaptive CTV derived from the first 6 treatment fractions using the STAPLE (Simultaneous Truth and Performance Level Estimation) algorithm, target coverage could be maintained using a single replan 1 week into therapy. For all approaches, normal tissue parameters (rectum V(70Gy) and NTCP) remained within acceptable limits. The frequency of adaptive interventions depends on the size of the CTV combined with target margins used during IMRT optimization. The application of adaptive target margins (<5 mm) to an adaptive CTV determined 1 week into therapy minimizes the need for subsequent dose replanning. Copyright © 2013 Elsevier Inc. All rights reserved.

Effect of Acute Gamma Irradiation on Curcuma alismatifolia Varieties and Detection of DNA Polymorphism through SSR Marker

PubMed Central

Taheri, Sima; Abdullah, Thohirah Lee; Ahmad, Zaiton; Abdullah, Nur Ashikin Psyquay

2014-01-01

The effects of eight different doses (0, 10, 20, 25, 35, 40, 60, and 100 Gy) of acute gamma irradiation on 44 (three varieties of Curcuma alismatifolia: Chiang Mai Red, Sweet Pink, Kimono Pink, and one Curcuma hybrid (Doi Tung 554) individual plants were investigated. Radiation sensitivity tests revealed that the LD50 values of the varieties were achieved at 21 Gy for Chiang Mai Red, 23 Gy for Sweet Pink, 25 Gy for Kimono Pink, and 28 Gy for Doi Tung 554. From the analysis of variance (ANOVA), significant variations were observed for vegetative traits, flowering development, and rhizome characteristics among the four varieties of Curcuma alismatifolia and dose levels as well as the dose × variety interaction. In irradiated plants, the leaf length, leaf width, inflorescence length, the number of true flowers, the number of pink bracts, number of shoots, plant height, rhizome size, number of storage roots, and number of new rhizomes decreased significantly (P < 0.05) as the radiation dose increased. The cophenetic correlation coefficient (CCC) between genetic dissimilarity matrix estimated from the morphological characters and the UPGMA clustering method was r = 0.93, showing a proof fit. In terms of genetic variation among the acutely irradiated samples, the number of presumed alleles revealed by simple sequence repeats ranged from two to seven alleles with a mean value of 3.1, 4.5, and 5.3 alleles per locus for radiation doses of 0, 10, and 20 Gy, respectively. The average values of the effective number of alleles, Nei's gene diversity, and Shannon's information index were 2.5–3.2, 0.51–0.66, and 0.9–1.3, respectively. The constructed dendrogram grouped the entities into seven clusters. Principal component analysis (PCA) supported the clustering results. Consequently, it was concluded that irradiation with optimum doses of gamma rays efficiently induces mutations in Curcuma alismatifolia varieties. PMID:24719878

Effect of acute gamma irradiation on Curcuma alismatifolia varieties and detection of DNA polymorphism through SSR marker.

PubMed

Taheri, Sima; Abdullah, Thohirah Lee; Ahmad, Zaiton; Abdullah, Nur Ashikin Psyquay

2014-01-01

The effects of eight different doses (0, 10, 20, 25, 35, 40, 60, and 100 Gy) of acute gamma irradiation on 44 (three varieties of Curcuma alismatifolia: Chiang Mai Red, Sweet Pink, Kimono Pink, and one Curcuma hybrid (Doi Tung 554) individual plants were investigated. Radiation sensitivity tests revealed that the LD50 values of the varieties were achieved at 21 Gy for Chiang Mai Red, 23 Gy for Sweet Pink, 25 Gy for Kimono Pink, and 28 Gy for Doi Tung 554. From the analysis of variance (ANOVA), significant variations were observed for vegetative traits, flowering development, and rhizome characteristics among the four varieties of Curcuma alismatifolia and dose levels as well as the dose × variety interaction. In irradiated plants, the leaf length, leaf width, inflorescence length, the number of true flowers, the number of pink bracts, number of shoots, plant height, rhizome size, number of storage roots, and number of new rhizomes decreased significantly (P < 0.05) as the radiation dose increased. The cophenetic correlation coefficient (CCC) between genetic dissimilarity matrix estimated from the morphological characters and the UPGMA clustering method was r = 0.93, showing a proof fit. In terms of genetic variation among the acutely irradiated samples, the number of presumed alleles revealed by simple sequence repeats ranged from two to seven alleles with a mean value of 3.1, 4.5, and 5.3 alleles per locus for radiation doses of 0, 10, and 20 Gy, respectively. The average values of the effective number of alleles, Nei's gene diversity, and Shannon's information index were 2.5-3.2, 0.51-0.66, and 0.9-1.3, respectively. The constructed dendrogram grouped the entities into seven clusters. Principal component analysis (PCA) supported the clustering results. Consequently, it was concluded that irradiation with optimum doses of gamma rays efficiently induces mutations in Curcuma alismatifolia varieties.

TU-H-CAMPUS-IeP1-03: Comparison of Monte Carlo Simulation and Conversion Factor Based Method On Estimation of Effective Dose in Pediatric Patients Undergoing Interventional Cardiac Procedures

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

Leung, K; Wong, M; Ng, Y

Purpose: Interventional cardiac procedures utilize frequent fluoroscopy and cineangiography, which impose considerable radiation risk to patients, especially pediatric patients. Accurate calculation of effective dose is important in order to estimate cancer risk over the rest of their lifetime. This study evaluates the difference in effective dose calculated by Monte Carlo simulation with those estimated by locally-derived conversion factors (CF-local) and by commonly quoted conversion factors from Karambatsakidou et al (CF-K). Methods: Effective dose (E),of 12 pediatric patients, age between 2.5–19 years old, who had undergone interventional cardiac procedures, were calculated using PCXMC-2.0 software. Tube spectrum, irradiation geometry, exposure parameters andmore » dose-area product (DAP) of each projection were included in the software calculation. Effective doses for each patient were also estimated by two Methods: 1) CF-local: conversion factor derived locally by generalizing results of 12 patients, multiplied by DAP of each patient gives E-local. 2) CF-K: selected factor from above-mentioned literature, multiplied by DAP of each patient gives E-K. Results: Mean of E, E-local and E-K were 16.01 mSv, 16.80 mSv and 22.25 mSv respectively. A deviation of −29.35% to +34.85% between E and E-local, while a greater deviation of −28.96% to +60.86% between E and EK were observed. E-K overestimated the effective dose for patients at age 7.5–19. Conclusion: Effective dose obtained by conversion factors is simple and quick to estimate radiation risk of pediatric patients. This study showed that estimation by CF-local may bear an error of 35% when compared with Monte Carlo calculation. If using conversion factors derived by other studies may result in an even greater error, of up to 60%, due to factors that are not catered for in the estimation, including patient size, projection angles, exposure parameters, tube filtration, etc. Users must be aware of these potential inaccuracies when simple conversion method is employed.« less

ESTIMATION OF EFFECTIVE DOSE FROM EXTERNAL EXPOSURE DUE TO SHORT-LIVED NUCLIDES IN THE PREFECTURES SURROUNDING FUKUSHIMA.

PubMed

Miyatake, Hirokazu; Yoshizawa, Nobuaki; Suzuki, Gen

2018-05-11

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted in a release of radionuclides into the environment. Since the accident, measurements of radiation in the environment such as air dose rate and deposition density of radionuclides have been performed by various 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 over widespread areas. Based on the data measured by JAEA, we estimated effective dose from external exposure in the prefectures surrounding Fukushima. Since car-borne survey started a few months after the accident, the main contribution to measured data comes from 137Cs and 134Cs whose half-lives are relatively long. Using air dose rate of 137Cs and 134Cs and the ratio of deposition density of short-lived nuclides to that of 137Cs and 134Cs, we also estimated contributions to the effective dose from other short-lived nuclides.

Space Radiation Organ Doses for Astronauts on Past and Future Missions

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.

2007-01-01

We review methods and data used for determining astronaut organ dose equivalents on past space missions including Apollo, Skylab, Space Shuttle, NASA-Mir, and International Space Station (ISS). Expectations for future lunar missions are also described. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra, or a related quantity, the lineal energy (y) spectra that is measured by a tissue equivalent proportional counter (TEPC). These data are used in conjunction with space radiation transport models to project organ specific doses used in cancer and other risk projection models. Biodosimetry data from Mir, STS, and ISS missions provide an alternative estimate of organ dose equivalents based on chromosome aberrations. The physical environments inside spacecraft are currently well understood with errors in organ dose projections estimated as less than plus or minus 15%, however understanding the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons for which there are no human data to estimate risks. The accuracy of projections of organ dose equivalents described here must be supplemented with research on the health risks of space exposure to properly assess crew safety for exploration missions.

Radiation exposure to foetus and breasts from dental X-ray examinations: effect of lead shields.

PubMed

Kelaranta, Anna; Ekholm, Marja; Toroi, Paula; Kortesniemi, Mika

2016-01-01

Dental radiography may involve situations where the patient is known to be pregnant or the pregnancy is noticed after the X-ray procedure. In such cases, the radiation dose to the foetus, though low, needs to be estimated. Uniform and widely used guidance on dental X-ray procedures during pregnancy are presently lacking, the usefulness of lead shields is unclear and practices vary. Upper estimates of radiation doses to the foetus and breasts of the pregnant patient were estimated with an anthropomorphic female phantom in intraoral, panoramic, cephalometric and CBCT dental modalities with and without lead shields. The upper estimates of foetal doses varied from 0.009 to 6.9 μGy, and doses at the breast level varied from 0.602 to 75.4 μGy. With lead shields, the foetal doses varied from 0.005 to 2.1 μGy, and breast doses varied from 0.002 to 10.4 μGy. The foetal dose levels without lead shielding were <1% of the annual dose limit of 1 mSv for a member of the public. Albeit the relative shielding effect, the exposure-induced increase in the risk of breast cancer death for the pregnant patient (based on the breast dose only) and the exposure-induced increase in the risk of childhood cancer death for the unborn child are minimal, and therefore, need for foetal and breast lead shielding was considered irrelevant. Most important is that pregnancy is never a reason to avoid or to postpone a clinically justified dental radiographic examination.

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.

Effective Dose Equivalent due to Cosmic Ray Particles and Their Secondary Particles on the Moon

NASA Astrophysics Data System (ADS)

Hayatsu, Kanako; Hareyama, Makoto; Kobayashi, Shingo; Karouji, Yuzuru; Sakurai, K.; Sihver, Lembit; Hasebe, N.

Estimation of radiation dose on and under the lunar surface is quite important for human activity on the Moon and for the future lunar bases construction. Radiation environment on the Moon is much different from that on the Earth. Galactic cosmic rays (GCRs) and solar energetic particles (SEPs) directly penetrate the lunar surface because of no atmosphere and no magnetic field around the Moon. Then, they generate many secondary particles such as neutrons, gamma rays and other charged particles by nuclear interactions with soils and regolith breccias under the lunar surface. Therefore, the estimation of radiation dose from them on the surface and the underground of the Moon are essential for safety human activities. In this study, the effective dose equivalents at the surface and various depths of the Moon were estimated using by the latest cosmic rays observation and developed calculation code. The largest contribution to the dose on the surface is primary charged particles in GCRs and SEPs, while in the ground, secondary neutrons are the most dominant. In particular, the dose from neutrons becomes maximal at 70-80 g/cm2 in depth of lunar soil, because fast neutrons with about 1.0 MeV are mostly produced at this depth and give the largest dose. On the lunar surface, the doses originated from large SEPs are very hazardous. We estimated the effective dose equivalents due to such large SEPs and the effects of aluminum shield for the large flare on the human body. In the presentation, we summarize and discuss the improved calculation results of radiation doses due to GCR particles and their secondary particles in the lunar subsurface. These results will provide useful data for the future exploration of the Moon.

Effect of Study Design on Sample Size in Studies Intended to Evaluate Bioequivalence of Inhaled Short‐Acting β‐Agonist Formulations

PubMed Central

Zeng, Yaohui; Singh, Sachinkumar; Wang, Kai

2017-01-01

Abstract Pharmacodynamic studies that use methacholine challenge to assess bioequivalence of generic and innovator albuterol formulations are generally designed per published Food and Drug Administration guidance, with 3 reference doses and 1 test dose (3‐by‐1 design). These studies are challenging and expensive to conduct, typically requiring large sample sizes. We proposed 14 modified study designs as alternatives to the Food and Drug Administration–recommended 3‐by‐1 design, hypothesizing that adding reference and/or test doses would reduce sample size and cost. We used Monte Carlo simulation to estimate sample size. Simulation inputs were selected based on published studies and our own experience with this type of trial. We also estimated effects of these modified study designs on study cost. Most of these altered designs reduced sample size and cost relative to the 3‐by‐1 design, some decreasing cost by more than 40%. The most effective single study dose to add was 180 μg of test formulation, which resulted in an estimated 30% relative cost reduction. Adding a single test dose of 90 μg was less effective, producing only a 13% cost reduction. Adding a lone reference dose of either 180, 270, or 360 μg yielded little benefit (less than 10% cost reduction), whereas adding 720 μg resulted in a 19% cost reduction. Of the 14 study design modifications we evaluated, the most effective was addition of both a 90‐μg test dose and a 720‐μg reference dose (42% cost reduction). Combining a 180‐μg test dose and a 720‐μg reference dose produced an estimated 36% cost reduction. PMID:29281130

Comparison of estimated human dose of (68)Ga-MAA with (99m)Tc-MAA based on rat data.

PubMed

Shanehsazzadeh, Saeed; Lahooti, Afsaneh; Yousefnia, Hassan; Geramifar, Parham; Jalilian, Amir Reza

2015-10-01

(99m)Tc macroaggregated albumin ((99m)Tc-MAA) that had been used as a perfusion agent has been evaluated. In this study, we tried to estimate human absorbed dose of ⁶⁸Ga-MAA via commercially available kit from Pars-Isotopes, based on biodistribution data in wild-type rats, and compare our estimation with the available absorbed dose data from (99m)Tc-MAA. For biodistribution of ⁶⁸Ga-MAA, three rats were sacrificed at each selected times after injection (15, 30, 45, 60, and 120 min) and the percentage of injected dose per gram of each organ was measured by direct counting from rats data from 11 harvested organs. The medical internal radiation dose formulation was applied to extrapolate from rats to human and to project the absorbed radiation dose for various organs in humans. The biodistribution data for ⁶⁸Ga-MAA showed that the most of the activity was taken up by the lung (more than 97 %) in no time. Our dose prediction shows that a 185-MBq injection of ⁶⁸Ga-MAA into humans might result in an estimated absorbed dose of 4.31 mGy in the whole body. The highest absorbed doses are observed in the adrenals, spleen, pancreas, and red marrow with 0.36, 0.34, 0.26, and 0.19 mGy, respectively. Since the (99m)Tc-MAA remains longer than ⁶⁸Ga-MAA in the lung and ⁶⁸Ga-MAA has good image qualities and results in lower amounts of dose delivery to the critical organs such as gonads, red marrow, and adrenals, the use of ⁶⁸Ga-MAA is recommended.

The dose from Compton backscatter screening.

PubMed

Rez, Peter; Metzger, Robert L; Mossman, Kenneth L

2011-04-01

Systems based on the detection of Compton backscattered X rays have been deployed for screening personnel for weapons and explosives. Similar principles are used for screening vehicles at border-crossing points. Based on well-established scattering cross sections and absorption coefficients in conjunction with reasonable estimates of the image contrast and resolution, the entrance skin dose and the dose at a depth of 1 cm can be calculated. The effective dose can be estimated using the same conversion coefficients as used to convert exposure measurements to the effective dose. It is shown that the effective dose is highly dependent on image resolution (i.e. pixel size).The effective doses for personnel screening systems are unlikely to be in compliance with the American National Standards Institute standard NS 43.17 unless the pixel sizes are >4 mm. Nevertheless, calculated effective doses are well below doses associated with health effects.

A macroscopic and microscopic study of radon exposure using Geant4 and MCNPX to estimate dose rates and DNA damage

NASA Astrophysics Data System (ADS)

van den Akker, Mary Evelyn

Radon is considered the second-leading cause of lung cancer after smoking. Epidemiological studies have been conducted in miner cohorts as well as general populations to estimate the risks associated with high and low dose exposures. There are problems with extrapolating risk estimates to low dose exposures, mainly that the dose-response curve at low doses is not well understood. Calculated dosimetric quantities give average energy depositions in an organ or a whole body, but morphological features of an individual can affect these values. As opposed to human phantom models, Computed Tomography (CT) scans provide unique, patient-specific geometries that are valuable in modeling the radiological effects of the short-lived radon progeny sources. Monte Carlo particle transport code Geant4 was used with the CT scan data to model radon inhalation in the main bronchial bifurcation. The equivalent dose rates are near the lower bounds of estimates found in the literature, depending on source volume. To complement the macroscopic study, simulations were run in a small tissue volume in Geant4-DNA toolkit. As an expansion of Geant4 meant to simulate direct physical interactions at the cellular level, the particle track structure of the radon progeny alphas can be analyzed to estimate the damage that can occur in sensitive cellular structures like the DNA molecule. These estimates of DNA double strand breaks are lower than those found in Geant4-DNA studies. Further refinements of the microscopic model are at the cutting edge of nanodosimetry research.

Development of posture-specific computational phantoms using motion capture technology and application to radiation dose-reconstruction for the 1999 Tokai-Mura nuclear criticality accident

NASA Astrophysics Data System (ADS)

Vazquez, Justin A.; Caracappa, Peter F.; Xu, X. George

2014-09-01

The majority of existing computational phantoms are designed to represent workers in typical standing anatomical postures with fixed arm and leg positions. However, workers found in accident-related scenarios often assume varied postures. This paper describes the development and application of two phantoms with adjusted postures specified by data acquired from a motion capture system to simulate unique human postures found in a 1999 criticality accident that took place at a JCO facility in Tokai-Mura, Japan. In the course of this accident, two workers were fatally exposed to extremely high levels of radiation. Implementation of the emergent techniques discussed produced more accurate and more detailed dose estimates for the two workers than were reported in previous studies. A total-body dose of 6.43 and 26.38 Gy was estimated for the two workers, who assumed a crouching and a standing posture, respectively. Additionally, organ-specific dose estimates were determined, including a 7.93 Gy dose to the thyroid and 6.11 Gy dose to the stomach for the crouching worker and a 41.71 Gy dose to the liver and a 37.26 Gy dose to the stomach for the standing worker. Implications for the medical prognosis of the workers are discussed, and the results of this study were found to correlate better with the patient outcome than previous estimates, suggesting potential future applications of such methods for improved epidemiological studies involving next-generation computational phantom tools.

Development of posture-specific computational phantoms using motion capture technology and application to radiation dose-reconstruction for the 1999 Tokai-Mura nuclear criticality accident.

PubMed

Vazquez, Justin A; Caracappa, Peter F; Xu, X George

2014-09-21

The majority of existing computational phantoms are designed to represent workers in typical standing anatomical postures with fixed arm and leg positions. However, workers found in accident-related scenarios often assume varied postures. This paper describes the development and application of two phantoms with adjusted postures specified by data acquired from a motion capture system to simulate unique human postures found in a 1999 criticality accident that took place at a JCO facility in Tokai-Mura, Japan. In the course of this accident, two workers were fatally exposed to extremely high levels of radiation. Implementation of the emergent techniques discussed produced more accurate and more detailed dose estimates for the two workers than were reported in previous studies. A total-body dose of 6.43 and 26.38 Gy was estimated for the two workers, who assumed a crouching and a standing posture, respectively. Additionally, organ-specific dose estimates were determined, including a 7.93 Gy dose to the thyroid and 6.11 Gy dose to the stomach for the crouching worker and a 41.71 Gy dose to the liver and a 37.26 Gy dose to the stomach for the standing worker. Implications for the medical prognosis of the workers are discussed, and the results of this study were found to correlate better with the patient outcome than previous estimates, suggesting potential future applications of such methods for improved epidemiological studies involving next-generation computational phantom tools.

Olfactory deposition of inhaled nanoparticles in humans

PubMed Central

Garcia, Guilherme J. M.; Schroeter, Jeffry D.; Kimbell, Julia S.

2016-01-01

Context Inhaled nanoparticles can migrate to the brain via the olfactory bulb, as demonstrated in experiments in several animal species. This route of exposure may be the mechanism behind the correlation between air pollution and human neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. Objectives This manuscript aims to (1) estimate the dose of inhaled nanoparticles that deposit in the human olfactory epithelium during nasal breathing at rest and (2) compare the olfactory dose in humans with our earlier dose estimates for rats. Materials and methods An anatomically-accurate model of the human nasal cavity was developed based on computed tomography scans. The deposition of 1–100 nm particles in the whole nasal cavity and its olfactory region were estimated via computational fluid dynamics (CFD) simulations. Our CFD methods were validated by comparing our numerical predictions for whole-nose deposition with experimental data and previous CFD studies in the literature. Results In humans, olfactory dose of inhaled nanoparticles is highest for 1–2 nm particles with approximately 1% of inhaled particles depositing in the olfactory region. As particle size grows to 100 nm, olfactory deposition decreases to 0.01% of inhaled particles. Discussion and conclusion Our results suggest that the percentage of inhaled particles that deposit in the olfactory region is lower in humans than in rats. However, olfactory dose per unit surface area is estimated to be higher in humans due to their larger minute volume. These dose estimates are important for risk assessment and dose-response studies investigating the neurotoxicity of inhaled nanoparticles. PMID:26194036

Benchmark dose analysis via nonparametric regression modeling

PubMed Central

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

2013-01-01

Estimation of benchmark doses (BMDs) in quantitative risk assessment traditionally is based upon parametric dose-response modeling. It is a well-known concern, however, that if the chosen parametric model is uncertain and/or misspecified, inaccurate and possibly unsafe low-dose inferences can result. We describe a nonparametric approach for estimating BMDs with quantal-response data based on an isotonic regression method, and also study use of corresponding, nonparametric, bootstrap-based confidence limits for the BMD. We explore the confidence limits’ small-sample properties via a simulation study, and illustrate the calculations with an example from cancer risk assessment. It is seen that this nonparametric approach can provide a useful alternative for BMD estimation when faced with the problem of parametric model uncertainty. PMID:23683057

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...

Patient-specific dose calculations for pediatric CT of the chest, abdomen and pelvis

PubMed Central

Fraser, Nicholas D.; Carver, Diana E.; Pickens, David R.; Price, Ronald R.; Hernanz-Schulman, Marta; Stabin, Michael G.

2015-01-01

Background Organ dose is essential for accurate estimates of patient dose from CT. Objective To determine organ doses from a broad range of pediatric patients undergoing diagnostic chest–abdomen–pelvis CT and investigate how these relate to patient size. Materials and methods We used a previously validated Monte Carlo simulation model of a Philips Brilliance 64 multi-detector CT scanner (Philips Healthcare, Best, The Netherlands) to calculate organ doses for 40 pediatric patients (M:F=21:19; range 0.6–17 years). Organ volumes and positions were determined from the images using standard segmentation techniques. Non-linear regression was performed to determine the relationship between volume CT dose index (CTDIvol)-normalized organ doses and abdominopelvic diameter. We then compared results with values obtained from independent studies. Results We found that CTDIvol-normalized organ dose correlated strongly with exponentially decreasing abdominopelvic diameter (R2>0.8 for most organs). A similar relationship was determined for effective dose when normalized by dose-length product (R2=0.95). Our results agreed with previous studies within 12% using similar scan parameters (i.e. bowtie filter size, beam collimation); however results varied up to 25% when compared to studies using different bowtie filters. Conclusion Our study determined that organ doses can be estimated from measurements of patient size, namely body diameter, and CTDIvol prior to CT examination. This information provides an improved method for patient dose estimation. PMID:26142256

Shot noise in radiobiological systems.

PubMed

Datesman, A

2016-11-01

As a model for human tissue, this report considers the rate of free radical generation in a dilute solution of water in which a beta-emitting radionuclide is uniformly dispersed. Each decay dissipates a discrete quantity of energy, creating a large number of free radicals in a short time within a small volume determined by the beta particle range. Representing the instantaneous dissipated power as a train of randomly-spaced pulses, the time-averaged dissipated power p¯ and rate of free radical generation g¯ are derived. The analogous result in the theory of electrical circuits is known as the shot noise theorem. The reference dose of X-rays D ref producing an identical rate of free radical generation and level of oxidative stress is shown a) to increase with the square root of the absorbed dose, D, and b) to be far larger than D. This finding may have important consequences for public health in cases where the level of shot noise exceeds some noise floor corresponding to equilibrium biological processes. An estimate of this noise floor is made using the example of potassium-40, a beta-emitting radioisotope universally present in living tissue. Copyright © 2016 Elsevier Ltd. All rights reserved.

Use of probability analysis to establish routine bioassay screening levels

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

Carbaugh, E.H.; Sula, M.J.; McFadden, K.M.

1990-09-01

Probability analysis was used by the Hanford Internal Dosimetry Program to establish bioassay screening levels for tritium and uranium in urine. Background environmental levels of these two radionuclides are generally detectable by the highly sensitive urine analysis procedures routinely used at Hanford. Establishing screening levels requires balancing the impact of false detection with the consequence of potentially undetectable occupation dose. To establish the screening levels, tritium and uranium analyses were performed on urine samples collected from workers exposed only to environmental sources. All samples were collected at home using a simulated 12-hour protocol for tritium and a simulated 24-hour collectionmore » protocol for uranium. Results of the analyses of these samples were ranked according to tritium concentration or total sample uranium. The cumulative percentile was calculated and plotted using log-probability coordinates. Geometric means and screening levels corresponding to various percentiles were estimated by graphical interpolation and standard calculations. The potentially annual internal dose associated with a screening level was calculated. Screening levels were selected corresponding to the 99.9 percentile, implying that, on the average, 1 out of 1000 samples collected from an unexposed worker population would be expected to exceed the screening level. 4 refs., 2 figs.« less

Radiation protection issues in galactic cosmic ray risk assessment

NASA Technical Reports Server (NTRS)

Sinclair, W. K.

1994-01-01

Radiation protection involves the limitation of exposure to below threshold doses for direct (or deterministic) effects and a knowledge of the risk of stochastic effects after low doses. The principal stochastic risk associated with low dose rate galactic cosmic rays is the increased risk of cancer. Estimates of this risk depend on two factors (a) estimates of cancer risk for low-LET radiation and (b) values of the appropriate radiation weighting factors, WR, for the high-LET radiations of galactic cosmic rays. Both factors are subject to considerable uncertainty. The low-LET cancer risk derived from the late effects of the atomic bombs is vulnerable to a number of uncertainties including especially that from projection in time, and from extrapolation from high to low dose rate. Nevertheless, recent low dose studies of workers and others tend to confirm these estimates. WR, relies on biological effects studied mainly in non-human systems. Additional laboratory studies could reduce the uncertainties in WR and thus produce a more confident estimate of the overall risk of galactic cosmic rays.

Radiation protection issues in galactic cosmic ray risk assessment.

PubMed

Sinclair, W K

1994-01-01

Radiation protection involves the limitation of exposure to below threshold doses for direct (or deterministic) effects and a knowledge of the risk of stochastic effects after low doses. The principal stochastic risk associated with low dose rate galactic cosmic rays is the increased risk of cancer. Estimates of this risk depend on two factors (a) estimates of cancer risk for low-LET radiation and (b) values of the appropriate radiation weighting factors, WR, for the high-LET radiations of galactic cosmic rays. Both factors are subject to considerable uncertainty. The low-LET cancer risk derived from the late effects of the atomic bombs is vulnerable to a number of uncertainties including especially that from projection in time, and from extrapolation from high to low dose rate. Nevertheless, recent low dose studies of workers and others tend to confirm these estimates. WR, relies on biological effects studied mainly in non-human systems. Additional laboratory studies could reduce the uncertainties in WR and thus produce a more confident estimate of the overall risk of galactic cosmic rays.

Accuracy of Monte Carlo simulations compared to in-vivo MDCT dosimetry

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

Bostani, Maryam, E-mail: mbostani@mednet.ucla.edu; McMillan, Kyle; Cagnon, Chris H.

Purpose: The purpose of this study was to assess the accuracy of a Monte Carlo simulation-based method for estimating radiation dose from multidetector computed tomography (MDCT) by comparing simulated doses in ten patients to in-vivo dose measurements. Methods: MD Anderson Cancer Center Institutional Review Board approved the acquisition of in-vivo rectal dose measurements in a pilot study of ten patients undergoing virtual colonoscopy. The dose measurements were obtained by affixing TLD capsules to the inner lumen of rectal catheters. Voxelized patient models were generated from the MDCT images of the ten patients, and the dose to the TLD for allmore » exposures was estimated using Monte Carlo based simulations. The Monte Carlo simulation results were compared to the in-vivo dose measurements to determine accuracy. Results: The calculated mean percent difference between TLD measurements and Monte Carlo simulations was −4.9% with standard deviation of 8.7% and a range of −22.7% to 5.7%. Conclusions: The results of this study demonstrate very good agreement between simulated and measured doses in-vivo. Taken together with previous validation efforts, this work demonstrates that the Monte Carlo simulation methods can provide accurate estimates of radiation dose in patients undergoing CT examinations.« less

Hanford Environmental Dose Reconstruction Project. Monthly report, December 1991

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

Finch, S.M.; McMakin, A.H.

1991-12-31

The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The TSP consists of experts in environmental pathways, epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering, radiation dosimetry, and cultural anthropology. Included are appointed technical members representing the states of Oregon and Washington, a representative of Native American tribes, and an individual representing the public.more » The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on human (dose estimates): Source Terms; Environmental Transport; Environmental Monitoring Data; Demographics, Agriculture, Food Habits and; Environmental Pathways and Dose Estimates.« less

Hanford Environmental Dose Reconstruction Project

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

Finch, S.M.; McMakin, A.H.

1991-01-01

The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The TSP consists of experts in environmental pathways, epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering, radiation dosimetry, and cultural anthropology. Included are appointed technical members representing the states of Oregon and Washington, a representative of Native American tribes, and an individual representing the public.more » The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on human (dose estimates): Source Terms; Environmental Transport; Environmental Monitoring Data; Demographics, Agriculture, Food Habits and; Environmental Pathways and Dose Estimates.« less

Dose Assessment of Los Alamos National Laboratory-Derived Residual Radionuclides in Soils within Tract A-18-2 for Land Conveyance and Transfer Decisions

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

Ruedig, Elizabeth; Whicker, Jeffrey Jay

In 2017, soil sampling for radiological materials was conducted within Tract A-18-2 specifically for land conveyance decisions. Measurements of radionuclides in soil samples were evaluated against a recreational use scenario, and all measurements were below screening action levels for each radionuclide. The total estimated dose was less than 1 mrem/y (< 10 μSv/y) for a hypothetical recreational user (compared to a dose limit of 25 mrem/y (250 μSv/y)). Dose estimates were based on the 95% upper confidence limits for radionuclide concentrations within the Tract. Additionally, dose estimates less than 3 mrem/y are considered to be As Low As Reasonably Achievable,more » so no follow-up analysis was conducted. Release of this property is consistent with the requirements of DOE Order 458.1 and Policy 412.« less

Practical applications of internal dose calculations

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

Carbaugh, E.H.

1994-06-01

Accurate estimates of intake magnitude and internal dose are the goal for any assessment of an actual intake of radioactivity. When only one datum is available on which to base estimates, the choices for internal dose assessment become straight-forward: apply the appropriate retention or excretion function, calculate the intake, and calculate the dose. The difficulty comes when multiple data and different types of data become available. Then practical decisions must be made on how to interpret conflicting data, or how to adjust the assumptions and techniques underlying internal dose assessments to give results consistent with the data. This article describesmore » nine types of adjustments which can be incorporated into calculations of intake and internal dose, and then offers several practical insights to dealing with some real-world internal dose puzzles.« less

Risks of secondary malignancies with heterotopic bone radiation therapy for patients younger than 40 years

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

Cadieux, Catherine L., E-mail: ccadieux@umail.iu.edu; DesRosiers, Colleen; McMullen, Kevin

Heterotopic ossification (HO) of the bone is defined as a benign condition in which abnormal bone formation occurs in soft tissue. One of the most common prophylactic treatments for HO is radiation therapy (RT). This study retrospectively reviewed 20 patients younger than the age of 40 who received radiation to prevent HO in a single fraction of 7 Gray. The purpose of this study is to assess the risk of a second malignancy in these patients by recreating their treatment fields and contouring organs at risk to estimate the radiation dose absorbed by normal tissues outside the radiation treatment field.more » Diagnostic computed tomography (CT) scans for each patient were used to recreate treatment fields and to calculate dose to structures of interest. The distance from the field edge to each structure and its depth was recorded. Dose measurements in a water phantom were performed for the range of depths, distances, and field sizes used in the actual treatment plans. Computer-generated doses were compared to estimates based on measurement. The structure dose recorded was the higher dose generated between the 2 methods. Scatter dose was recorded to the rectum, bladder, sigmoid colon, small bowel, ovaries and utero-cervix in female patients, and prostate and gonads in male patients. In some patients, there is considerable dose received by certain organs from scatter because of their proximity to the radiation field. The average dose to the ovarian region was 4.125 Gy with a range of 1.085 to 6.228 Gy. The risk estimate for these patients ranged from 0.16% to 0.93%. The average total lifetime risk estimate for the bladder in all patients is 0.22% and the average total lifetime risk estimate for the remainder organs in all patients is 1.25%. In conclusions, proper shielding created from multileaf collimators (MLCs), blocks, and shields should always be used when possible.« less

Fluence-to-dose conversion coefficients for heavy ions calculated using the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Niita, Koji

2010-04-21

The fluence to organ-absorbed-dose and effective-dose conversion coefficients for heavy ions with atomic numbers up to 28 and energies from 1 MeV/nucleon to 100 GeV/nucleon were calculated using the PHITS code coupled to the ICRP/ICRU adult reference computational phantoms, following the instruction given in ICRP Publication 103 (2007 (Oxford: Pergamon)). The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. The calculation results indicate that the effective dose can generally give a conservative estimation of the effective dose equivalent for heavy-ion exposure, although it is occasionally too conservative especially for high-energy lighter-ion irradiations. It is also found from the calculation that the conversion coefficients for the Q(y)-based effective dose equivalents are generally smaller than the corresponding Q(L)-based values because of the conceptual difference between LET and y as well as the numerical incompatibility between the Q(L) and Q(y) relationships. The calculated data of these dose conversion coefficients are very useful for the dose estimation of astronauts due to cosmic-ray exposure.

The effect of Haemophilus influenzae type B and pneumococcal conjugate vaccines on childhood meningitis mortality: a systematic review

PubMed Central

2013-01-01

Background Two of the most prevalent causes of severe bacterial meningitis in children, Haemophilus influenzae type B (Hib) and Streptococcus pneumoniae, are preventable by existing vaccines increasingly available in developing countries. Our objective was to estimate the dose-specific effect of Hib and pneumococcal conjugate vaccines (PCV) on childhood meningitis mortality in low-income countries for use in the Lives Saved Tool (LiST). Methods We systematically searched and reviewed published vaccine efficacy trials and observational studies reporting the effect of Hib or PCV vaccines on organism-specific meningitis, bacterial meningitis and all-cause meningitis incidence and mortality among children less than five years old in low- and middle-income countries. Data collection and quality assessments were performed using standardized guidelines. For outcomes available across multiple studies (≥2) and approximating meningitis mortality, we pooled estimates reporting dose-specific effects using random effects meta-analytic methods, then combined these with meningitis etiology data to determine the preventable fraction of childhood meningitis mortality for inclusion in LiST. Results We identified 18 studies of Hib conjugate vaccines reporting relevant meningitis morbidity and mortality outcomes (2 randomized controlled trials [RCTs], 16 observational studies) but few provided dose-specific effects. A meta-analysis of four case-control studies examined the dose-specific effect of Hib conjugate vaccines on Hib meningitis morbidity (1 dose: RR=0.64, 95% CI 0.38-1.06; 2 doses: RR=0.09, 95% CI 0.03-0.27; 3 doses: RR=0.06, 95% CI 0.02-0.22), consistent with results from single RCTs. Pooled estimates of two RCTs provided evidence for the effect of three doses of PCV on vaccine-serotype meningitis morbidity (RR=0.16, 95% CI 0.02-1.20). We considered these outcomes of severe disease as proxy estimates for meningitis mortality and combined the estimates of protective effects with meningitis etiology data to provide an estimate of the preventable fraction of childhood meningitis mortality with three doses of Hib (38-43%) and pneumococcal conjugate vaccines (28-35%) for use in LiST. Conclusions Few RCTs or vaccine effectiveness studies evaluated the dose-specific impact of Hib and PCV vaccines on childhood meningitis mortality, necessitating use of proxy measures to estimate population impact in LiST. Our analysis indicates that approximately three-quarters of meningitis deaths are preventable with existing Hib and PCV vaccines. PMID:24564188

Human papillomavirus (HPV) vaccination coverage in young Australian women is higher than previously estimated: independent estimates from a nationally representative mobile phone survey.

PubMed

Brotherton, Julia M L; Liu, Bette; Donovan, Basil; Kaldor, John M; Saville, Marion

2014-01-23

Accurate estimates of coverage are essential for estimating the population effectiveness of human papillomavirus (HPV) vaccination. Australia has a purpose built National HPV Vaccination Program Register for monitoring coverage, however notification of doses administered to young women in the community during the national catch-up program (2007-2009) was not compulsory. In 2011, we undertook a population-based mobile phone survey of young women to independently estimate HPV vaccination coverage. Randomly generated mobile phone numbers were dialed to recruit women aged 22-30 (age eligible for HPV vaccination) to complete a computer assisted telephone interview. Consent was sought to validate self reported HPV vaccination status against the national register. Coverage rates were calculated based on self report and weighted to the age and state of residence structure of the Australian female population. These were compared with coverage estimates from the register using Australian Bureau of Statistics estimated resident populations as the denominator. Among the 1379 participants, the national estimate for self reported HPV vaccination coverage for doses 1/2/3, respectively, weighted for age and state of residence, was 64/59/53%. This compares with coverage of 55/45/32% and 49/40/28% based on register records, using 2007 and 2011 population data as the denominators respectively. Some significant differences in coverage between the states were identified. 20% (223) of women returned a consent form allowing validation of doses against the register and provider records: among these women 85.6% (538) of self reported doses were confirmed. We confirmed that coverage rates for young women vaccinated in the community (at age 18-26 years) are underestimated by the national register and that under-notification is greater for second and third doses. Using 2011 population estimates, rather than estimates contemporaneous with the program rollout, reduces register-based coverage estimates further because of large population increases due to immigration since the program. Copyright © 2013 Elsevier Ltd. All rights reserved.

SU-E-J-66: Significant Anatomical and Dosimetric Changes Observed with the Pharyngeal Constrictor During Head and Neck Radiotherapy Elicited From Daily Deformable Image Registration and Dose Accumulation

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

Kumarasiri, A; Siddiqui, F; Liu, C

2015-06-15

Purpose: To evaluate the anatomical changes and associated dosimetric consequences to the pharyngeal constrictor (PC) that occurs during head and neck radiotherapy (H&N RT). Methods: A cohort of 13 oro-pharyngeal cancer patients, who had daily CBCT’s for localization, was retrospectively studied. On every 5th CBCT, PC was manually delineated by a radiation oncologist. The anterior-posterior PC thickness was measured at the C3 level. Delivered dose to PC was estimated by calculating daily doses on CBCT’s, and accumulating to corresponding planning CT images. For accumulation, a parameter-optimized B- spline-based deformable image registration algorithm (Elastix) was used, in conjunction with an energy-massmore » mapping dose transfer algorithm. Mean and maximum dose (Dmean, Dmax) to PC was determined and compared with corresponding planned quantities. Results: The mean (±standard deviation) volume increase (ΔV) and thickness increase (Δt) over the course of 35 total fractions were 54±33% (11.9±7.6 cc), and 63±39% (2.9±1.9 mm), respectively. The resultant cumulative mean dose increase from planned dose to PC (ΔDmean) was 1.4±1.3% (0.9±0.8 Gy), while the maximum dose increase (ΔDmax) was 0.0±1.6% (0.0±1.1 Gy). Patients with adaptive replanning (n=6) showed a smaller mean dose increase than those without (n=7); 0.5±0.2% (0.3±0.1 Gy) vs. 2.2±1.4% (1.4±0.9 Gy). There was a statistically significant (p<0.0001) strong correlation between ΔDmean and Δt (Pearson coefficient r=0.78), and a moderate-to-strong correlation (r=0.52) between ΔDmean and ΔV. Correlation between ΔDmean and weight loss ΔW (r=0.1), as well as ΔV and ΔW (r=0.2) were negligible. Conclusion: Patients were found to undergo considerable anatomical changes to pharyngeal constrictor during H&N RT, resulting in non-negligible dose deviations from intended dose. Results are indicative that pharyngeal constrictor thickness, measured at C3 level, is a good predictor for the dose change to the organ. Daily deformable registration and dose accumulation provide a reliable means to assess important anatomical and dosimetric changes to pharyngeal constrictor occurring during treatment. This work was supported in part by a research grant from Varian Medical Systems, Palo Alto, CA.« less

Radiation leukaemogenesis at low doses DE-FG02-05 ER 63947 Final Technical Report 15 May 2005; 14 May 2010

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

Bouffler, Simon

2010-07-28

This report provides a complete summary of the work undertaken and results obtained under US Department of Energy grant DF-FG02-05 ER 63947, Radiation leukaemogenesis at low doses. There is ample epidemiological evidence indicating that ionizing radiation is carcinogenic in the higher dose range. This evidence, however, weakens and carries increasing uncertainties at doses below 100-200 mSv. At these low dose levels the form of the dose-response curve for radiation-induced cancer cannot be determined reliably or directly from studies of human populations. Therefore animal, cellular and other experimental systems must be employed to provide supporting evidence on which to base judgementsmore » of risk at low doses. Currently in radiological protection a linear non-threshold (LNT) extrapolation of risk estimates derived from human epidemiological studies is used to estimate risks in the dose range of interest for protection purposes. Myeloid leukaemias feature prominently among the cancers associated with human exposures to ionising radiation (eg UNSCEAR 2006; IARC 2000). Good animal models of radiation-induced acute myeloid leukaemia (AML) are available including strains such as CBA, RFM and SJL (eg Major and Mole 1978; Ullrich et al 1976; Resnitzky et al 1985). Early mechanistic studies using cytogenetic methods in these mouse models established that the majority of radiation-induced AMLs carried substantial interstitial deletions in one copy of chromosome (chr) 2 (eg Hayata et al 1983; Trakhtenbrot et al 1988; Breckon et al 1991; Rithidech et al 1993; Bouffler et al 1996). Chr2 aberrations are known to occur in bone marrow cells as early as 24 hours after in vivo irradiation (Bouffler et al 1997). Subsequent molecular mapping studies defined a distinct region of chr2 that is commonly lost in AMLs (Clark et al 1996; Silver et al 1999). Further, more detailed, analysis identified point mutations at a specific region of the Sfpi1/PU.1 haemopoietic transcription factor gene which lies in the commonly deleted region of chr2 (Cook et al 2004; Suraweera et al 2005). These lines of evidence strongly implicate the Sfpi1/PU.1 gene as a tumour suppressor gene, dysregulation of which leads to myeloid leukaemia. The main focus of this project was to utilize the CBA mouse model of radiation leukaemogenesis to explore mechanisms of low dose and low dose-rate leukaemogenesis. A series of mechanistic investigations were undertaken, the central aim of which was to identify the events that convert normal cells into myeloid leukaemia cells and explore the dose-response relationships for these. Much of the work centred on the Sfpi1/PU.1 gene and its role in leukaemogenesis. Specific studies considered the dose-response and time-course relationships for loss of the gene, the functional consequences of Sfpi1/PU.1 loss and mutation on transcriptional programmes and developing an in vivo reporter gene system for radiation-induced alterations to PU.1 expression. Additional work sought further genetic changes associated with radiation-induced AMLs and a better characterization of the cell of origin or 'target cell' for radiation-induced AML. All the information gathered is of potential use in developing biologically realistic mathematical models for low dose cancer risk projection.« less

Statistical analysis of nonmonotonic dose-response relationships: research design and analysis of nasal cell proliferation in rats exposed to formaldehyde.

PubMed

Gaylor, David W; Lutz, Werner K; Conolly, Rory B

2004-01-01

Statistical analyses of nonmonotonic dose-response curves are proposed, experimental designs to detect low-dose effects of J-shaped curves are suggested, and sample sizes are provided. For quantal data such as cancer incidence rates, much larger numbers of animals are required than for continuous data such as biomarker measurements. For example, 155 animals per dose group are required to have at least an 80% chance of detecting a decrease from a 20% incidence in controls to an incidence of 10% at a low dose. For a continuous measurement, only 14 animals per group are required to have at least an 80% chance of detecting a change of the mean by one standard deviation of the control group. Experimental designs based on three dose groups plus controls are discussed to detect nonmonotonicity or to estimate the zero equivalent dose (ZED), i.e., the dose that produces a response equal to the average response in the controls. Cell proliferation data in the nasal respiratory epithelium of rats exposed to formaldehyde by inhalation are used to illustrate the statistical procedures. Statistically significant departures from a monotonic dose response were obtained for time-weighted average labeling indices with an estimated ZED at a formaldehyde dose of 5.4 ppm, with a lower 95% confidence limit of 2.7 ppm. It is concluded that demonstration of a statistically significant bi-phasic dose-response curve, together with estimation of the resulting ZED, could serve as a point-of departure in establishing a reference dose for low-dose risk assessment.

Converging stereotactic radiotherapy using kilovoltage X-rays: experimental irradiation of normal rabbit lung and dose-volume analysis with Monte Carlo simulation.

PubMed

Kawase, Takatsugu; Kunieda, Etsuo; Deloar, Hossain M; Tsunoo, Takanori; Seki, Satoshi; Oku, Yohei; Saitoh, Hidetoshi; Saito, Kimiaki; Ogawa, Eileen N; Ishizaka, Akitoshi; Kameyama, Kaori; Kubo, Atsushi

2009-10-01

To validate the feasibility of developing a radiotherapy unit with kilovoltage X-rays through actual irradiation of live rabbit lungs, and to explore the practical issues anticipated in future clinical application to humans through Monte Carlo dose simulation. A converging stereotactic irradiation unit was developed, consisting of a modified diagnostic computed tomography (CT) scanner. A tiny cylindrical volume in 13 normal rabbit lungs was individually irradiated with single fractional absorbed doses of 15, 30, 45, and 60 Gy. Observational CT scanning of the whole lung was performed every 2 weeks for 30 weeks after irradiation. After 30 weeks, histopathologic specimens of the lungs were examined. Dose distribution was simulated using the Monte Carlo method, and dose-volume histograms were calculated according to the data. A trial estimation of the effect of respiratory movement on dose distribution was made. A localized hypodense change and subsequent reticular opacity around the planning target volume (PTV) were observed in CT images of rabbit lungs. Dose-volume histograms of the PTVs and organs at risk showed a focused dose distribution to the target and sufficient dose lowering in the organs at risk. Our estimate of the dose distribution, taking respiratory movement into account, revealed dose reduction in the PTV. A converging stereotactic irradiation unit using kilovoltage X-rays was able to generate a focused radiobiologic reaction in rabbit lungs. Dose-volume histogram analysis and estimated sagittal dose distribution, considering respiratory movement, clarified the characteristics of the irradiation received from this type of unit.

Evaluation of the annual Canadian biodosimetry network intercomparisons

PubMed Central

Wilkins, Ruth C.; Beaton-Green, Lindsay A.; Lachapelle, Sylvie; Kutzner, Barbara C.; Ferrarotto, Catherine; Chauhan, Vinita; Marro, Leonora; Livingston, Gordon K.; Boulay Greene, Hillary; Flegal, Farrah N.

2015-01-01

Abstract Purpose: To evaluate the importance of annual intercomparisons for maintaining the capacity and capabilities of a well-established biodosimetry network in conjunction with assessing efficient and effective analysis methods for emergency response. Materials and methods: Annual intercomparisons were conducted between laboratories in the Canadian National Biological Dosimetry Response Plan. Intercomparisons were performed over a six-year period and comprised of the shipment of 10–12 irradiated, blinded blood samples for analysis by each of the participating laboratories. Dose estimates were determined by each laboratory using the dicentric chromosome assay (conventional and QuickScan scoring) and where possible the cytokinesis block micronucleus (CBMN) assay. Dose estimates were returned to the lead laboratory for evaluation and comparison. Results: Individual laboratories performed comparably from year to year with only slight fluctuations in performance. Dose estimates using the dicentric chromosome assay were accurate about 80% of the time and the QuickScan method for scoring the dicentric chromosome assay was proven to reduce the time of analysis without having a significant effect on the dose estimates. Although analysis with the CBMN assay was comparable to QuickScan scoring with respect to speed, the accuracy of the dose estimates was greatly reduced. Conclusions: Annual intercomparisons are necessary to maintain a network of laboratories for emergency response biodosimetry as they evoke confidence in their capabilities. PMID:25670072

Assessing vaccination coverage in infants, survey studies versus the Flemish immunisation register: achieving the best of both worlds.

PubMed

Braeckman, Tessa; Lernout, Tinne; Top, Geert; Paeps, Annick; Roelants, Mathieu; Hoppenbrouwers, Karel; Van Damme, Pierre; Theeten, Heidi

2014-01-09

Infant immunisation coverage in Flanders, Belgium, is monitored through repeated coverage surveys. With the increased use of Vaccinnet, the web-based ordering system for vaccines in Flanders set up in 2004 and linked to an immunisation register, this database could become an alternative to quickly estimate vaccination coverage. To evaluate its current accuracy, coverage estimates generated from Vaccinnet alone were compared with estimates from the most recent survey (2012) that combined interview data with data from Vaccinnet and medical files. Coverage rates from registrations in Vaccinnet were systematically lower than the corresponding estimates obtained through the survey (mean difference 7.7%). This difference increased by dose number for vaccines that require multiple doses. Differences in administration date between the two sources were observed for 3.8-8.2% of registered doses. Underparticipation in Vaccinnet thus significantly impacts on the register-based immunisation coverage estimates, amplified by underregistration of administered doses among vaccinators using Vaccinnet. Therefore, survey studies, despite being labour-intensive and expensive, currently provide more complete and reliable results than register-based estimates alone in Flanders. However, further improvement of Vaccinnet's completeness will likely allow more accurate estimates in the nearby future. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dentalmaps: Automatic Dental Delineation for Radiotherapy Planning in Head-and-Neck Cancer

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

Thariat, Juliette, E-mail: jthariat@hotmail.com; Ramus, Liliane; INRIA

Purpose: To propose an automatic atlas-based segmentation framework of the dental structures, called Dentalmaps, and to assess its accuracy and relevance to guide dental care in the context of intensity-modulated radiotherapy. Methods and Materials: A multi-atlas-based segmentation, less sensitive to artifacts than previously published head-and-neck segmentation methods, was used. The manual segmentations of a 21-patient database were first deformed onto the query using nonlinear registrations with the training images and then fused to estimate the consensus segmentation of the query. Results: The framework was evaluated with a leave-one-out protocol. The maximum doses estimated using manual contours were considered as groundmore » truth and compared with the maximum doses estimated using automatic contours. The dose estimation error was within 2-Gy accuracy in 75% of cases (with a median of 0.9 Gy), whereas it was within 2-Gy accuracy in 30% of cases only with the visual estimation method without any contour, which is the routine practice procedure. Conclusions: Dose estimates using this framework were more accurate than visual estimates without dental contour. Dentalmaps represents a useful documentation and communication tool between radiation oncologists and dentists in routine practice. Prospective multicenter assessment is underway on patients extrinsic to the database.« less

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.

Reconstruction of limited-angle dual-energy CT using mutual learning and cross-estimation (MLCE)

NASA Astrophysics Data System (ADS)

Zhang, Huayu; Xing, Yuxiang

2016-03-01

Dual-energy CT (DECT) imaging has gained a lot of attenuation because of its capability to discriminate materials. We proposes a flexible DECT scan strategy which can be realized on a system with general X-ray sources and detectors. In order to lower dose and scanning time, our DECT acquires two projections data sets on two arcs of limited-angular coverage (one for each energy) respectively. Meanwhile, a certain number of rays from two data sets form conjugate sampling pairs. Our reconstruction method for such a DECT scan mainly tackles the consequent limited-angle problem. Using the idea of artificial neural network, we excavate the connection between projections at two different energies by constructing a relationship between the linear attenuation coefficient of the high energy and that of the low one. We use this relationship to cross-estimate missing projections and reconstruct attenuation images from an augmented data set including projections at views covered by itself (projections collected in scanning) and by the other energy (projections estimated) for each energy respectively. Validated by our numerical experiment on a dental phantom with rather complex structures, our DECT is effective in recovering small structures in severe limited-angle situations. This DECT scanning strategy can much broaden DECT design in reality.

Trends in calcium supplementation, National Health and Nutrition Examination Survey (NHANES) 1999-2014.

PubMed

Rooney, Mary R; Michos, Erin D; Hootman, Katie C; Harnack, Lisa; Lutsey, Pamela L

2018-06-01

Long-term outcomes of supplemental calcium are inadequately understood. Recent research suggests that calcium from supplements may not be entirely free from unintended health consequences. Consequently, it is important to understand patterns and trends in use of calcium supplements. To report trends in supplemental calcium intake between 1999 and 2014, using NHANES data, overall and stratified by sex, race/ethnicity and age. A total of 42,038 adult NHANES participants were included in this analysis. For each survey period, we calculated the prevalence of calcium supplement use exceeding the Estimated Average Requirement (EAR) and Tolerable Upper Intake Levels (UL), and mean daily supplemental calcium dose among calcium-containing supplement users. Sample weights were applied. Linear regression was used to examine trends. Overall, the prevalence of calcium supplement use at a dose ≥EAR increased between 1999 and 2000 and 2013-2014, from 2.5% (95% CI: 1.9-3.3%) to 4.6% (3.8-5.5%). Use ≥EAR peaked in 2003-2004 at 6.7% (5.3-8.5%) (p-quadratic trend<0.001). Mean supplemental calcium intake peaked in 2007-2008, thereafter decreasing (p-quadratic trend<0.001). The overall prevalence of intake ≥UL from supplemental calcium in 2013-2014 was 0.4% (0.2-0.8%). Use of supplemental calcium ≥UL peaked during 2007-2008 at 1.2% (0.7-2.0%). In all time periods, supplemental calcium intake tended to be greater among women, non-Hispanic whites and adults >60years. We described the prevalence of U.S. adults consuming supplemental calcium ≥UL and ≥ EAR. While few were consuming supplemental calcium ≥UL, consumption ≥EAR was not uncommon, especially among women, non-Hispanic whites and older adults. Copyright © 2018 Elsevier Inc. All rights reserved.

Investigation of the exposure to radon and progeny in the thermal spas of Loutraki (Attica-Greece): results from measurements and modelling.

PubMed

Nikolopoulos, Dimitrios; Vogiannis, Efstratios; Petraki, Ermioni; Zisos, Athanasios; Louizi, Anna

2010-01-01

Radon and progeny ((218)Po, (214)Pb, (214)Bi and (214)Po) in thermal spas are well known radioactive pollutants identified for additional radiation burden of patients due to the activity concentration peaks which appear during bath treatment or due to drinking of waters of high radon content. This burden affects additionally the working personnel of the spas. The present paper has focused on the thermal spas of Loutraki (Attica-Greece). The aim was the investigation of the health impact for patients and working personnel due to radon and progeny. Attention has been paid to radon and progeny transient concentration peaks (for bath treatment) and to radon of thermal waters (both for bath treatment and drinking therapy). Designed experiments have been carried out, which included radon and progeny activity concentration measurements in thermal waters and ambient air. Additionally, published models for description of radon and progeny transient concentration peaks were employed. The models were based on physicochemical processes involved and employed non linear first order derivative mass balance differential equations which were solved numerically with the aid of specially developed computer codes. The collected measurements were analysed incorporating these models. Results were checked via non linear statistical tests. Predictions and measurements were found in close agreement. Non linear parameters were estimated. The models were employed for dosimetric estimations of patients and working personnel. The effective doses of patients receiving bath treatment were found low but not negligible. The corresponding doses to patients receiving potable treatment were found high but below the proposed international limits. It was found that the working personnel are exposed to considerable effective doses, however well below the acceptable limits for workers. It was concluded that treatment and working in the Loutraki spas leads to intense variations of radon and progeny and consequently additional health impact both to patients and working personnel.

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. However, the overall risk of cancer incidence attributable to the CT examination was much higher for the newborn (2.4 in 1000) than for the teenager (0.7 in 1000). For the two pediatric-aged patients in our study, CTDIvol underestimated dose to large organs in the scan coverage by 30%–48%. The effective dose derived from DLP using published conversion coefficients differed from that calculated using patient-specific organ dose values by −57% to 13%, when the tissue weighting factors of ICRP 60 were used, and by −63% to 28%, when the tissue weighting factors of ICRP 103 were used. Conclusions: It is possible to estimate patient-specific radiation dose and cancer risk from CT examinations by combining a validated Monte Carlo program with patient-specific anatomical models that are derived from the patients’ clinical CT data and supplemented by transformed models of reference adults. With the construction of a large library of patient-specific computer models encompassing patients of all ages and weight percentiles, dose and risk can be estimated for any patient prior to or after a CT examination. Such information may aid in decisions for image utilization and can further guide the design and optimization of CT technologies and scan protocols. PMID:21361209

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 patients. However, the overall risk of cancer incidence attributable to the CT examination was much higher for the newborn (2.4 in 1000) than for the teenager (0.7 in 1000). For the two pediatric-aged patients in our study, CTDI{sub vol} underestimated dose to large organs in the scan coverage by 30%-48%. The effective dose derived from DLP using published conversion coefficients differed from that calculated using patient-specific organ dose values by -57% to 13%, when the tissue weighting factors of ICRP 60 were used, and by -63% to 28%, when the tissue weighting factors of ICRP 103 were used. Conclusions: It is possible to estimate patient-specific radiation dose and cancer risk from CT examinations by combining a validated Monte Carlo program with patient-specific anatomical models that are derived from the patients' clinical CT data and supplemented by transformed models of reference adults. With the construction of a large library of patient-specific computer models encompassing patients of all ages and weight percentiles, dose and risk can be estimated for any patient prior to or after a CT examination. Such information may aid in decisions for image utilization and can further guide the design and optimization of CT technologies and scan protocols.« 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.

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

Sun, Li-Min, E-mail: limin.sun@yahoo.com; Huang, Chih-Jen; Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan

Acute skin reaction during adjuvant radiotherapy for breast cancer is an inevitable process, and its severity is related to the skin dose. A high–skin dose area can be speculated based on the isodose distribution shown on a treatment planning. To determine whether treatment planning can reflect high–skin dose location, 80 patients were collected and their skin doses in different areas were measured using a thermoluminescent dosimeter to locate the highest–skin dose area in each patient. We determined whether the skin dose is consistent with the highest-dose area estimated by the treatment planning of the same patient. The χ{sup 2} andmore » Fisher exact tests revealed that these 2 methods yielded more consistent results when the highest-dose spots were located in the axillary and breast areas but not in the inframammary area. We suggest that skin doses shown on the treatment planning might be a reliable and simple alternative method for estimating the highest skin doses in some areas.« less

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.

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.