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Sample records for absorbed doses estimated

  1. Radiation environments and absorbed dose estimations on manned space missions.

    PubMed

    Curtis, S B; Atwell, W; Beever, R; Hardy, A

    1986-01-01

    In order to make an assessment of radiation risk during manned missions in space, it is necessary first to have as accurate an estimation as possible of the radiation environment within the spacecraft to which the astronauts will be exposed. Then, with this knowledge and the inclusion of body self-shielding, estimations can be made of absorbed doses for various body organs (skin, eye, blood-forming organs, etc.). A review is presented of our present knowledge of the radiation environments and absorbed doses expected for several space mission scenarios selected for our development of the new radiation protection guidelines. The scenarios selected are a 90-day mission at an altitude (450 km) and orbital inclinations (28.5 degrees, 57 degrees and 90 degrees) appropriate for NASA's Space Station, a 15-day sortie to geosynchronous orbit and a 90-day lunar mission. All scenarios chosen yielded dose equivalents between five and ten rem to the blood forming organs if no large solar particle event were encountered. Such particle events could add considerable exposure particularly to the skin and eye for all scenarios except the one at 28.5 degrees orbital inclination.

  2. Radiation absorbed dose estimates for 18F-BPA PET.

    PubMed

    Kono, Yuzuru; Kurihara, Hiroaki; Kawamoto, Hiroshi; Yasui, Naoko; Honda, Naoki; Igaki, Hiroshi; Itami, Jun

    2017-01-01

    Background Boron neutron capture therapy (BNCT) is a molecular radiation therapy approach based on the (10)B (n, α) (7)Li nuclear reaction in cancer cells. In BNCT, delivery of (10)B in the form of 4-borono-phenylalanine conjugated with fructose (BPA-fr) to the cancer cells is important. The PET tracer 4-borono-2-18F-fluoro-phenylalanine (FBPA) has been used to predict the accumulation of BPA-fr before BNCT. Purpose To determine the biodistribution and dosimetric parameters in 18F-BPA PET/CT studies. Material and Methods Human biokinetic data were obtained during clinical 18F-BPA PET studies between February and June 2015 at one institution. Nine consecutive patients were studied prospectively. The internal radiation dose was calculated on the basis of radioactivity data from blood, urine, and normal tissue of the heart, liver, spleen, kidney, and other parts of the body at each time point using OLINDA/EXM1.1 program. We compared our calculations with published 18F-FDG data. Results Adult patients (3 men, 3 women; age range, 28-68 years) had significantly smaller absorbed doses than pediatric patients (3 patients; age range, 5-12 years) ( P = 0.003). The mean effective dose was 57% lower in adult patients compared with pediatric patients. Mean effective doses for 18F-BPA were 25% lower than those for 18F-FDG presented in International Commission of Radiation Protection (ICRP) publication 106. Conclusion We found significant differences in organ absorbed doses for 18F-BPA against those for 18F-FDG presented in ICRP publication 106. Mean effective doses for 18F-BPA were smaller than those for 18F-FDG in the publication by 0.5-38% (mean difference, 25%).

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

    SciTech Connect

    Norris, Edward T.; Liu, Xin; Hsieh, Jiang

    2015-07-15

    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. The 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

  4. SU-E-I-85: Absorbed Dose Estimation for a Commercially Available MicroCT Scanner

    SciTech Connect

    Lau, A; Ahmad, S; Chen, Y; Ren, L; Liu, H; Yang, K

    2015-06-15

    Purpose: To quantify the simulated absorbed dose delivered for a typical scan from a commercially available microCT scanner in order to aid in the dose estimation. Methods: The simulations were conducted using the Geant4 Monte Carlo Toolkit (version 10) with the standard electromagnetic classes. The Quantum FX microCT scanner (PerkinElmer, Waltham, MA) was modeled incorporating the energy fluence and angular distributions of generated photons, spatial dimensions of nominal source-to-object and source-to-detector distances. The energy distribution was measured using a spectrometer (X-123CdTe, Amptek Inc., Bedford, USA) with a 300 angular spread from the source for the 90 kVp X-ray beams with no additional filtration. The nominal distances from the source to object consisted of three setups: 154.0 mm, 104.0 mm, and 51.96 mm. Our simulations recorded the dose absorbed in a cylindrical phantom of PMMA with a fixed length of 2 cm and varying radii (10, 20, 30 and 40 mm) using 100 million incident photons. The averaged absorbed dose in the object was then quantified for all setups. An exposure measurement of 417 mR was taken using a Radcal 9095 system utilizing 10×9–180 ion chamber with the given technique of 90 kVp, 63 μA, and 12 s. The exposure rate was also simulated with same setup to calculate the conversion factor of the beam current and the number of incident photons. Results: For a typical cone-beam scan with non-filtered 90kVp, the dose coefficients (the absorbed dose per mAs) were 2.614, 2.549 and 2.467 μGy/mAs under source to object distance of 104 mm for the object diameters of 10 mm, 20 mm and 30 mm, respectively. Conclusion: A look-up table was developed where an investigator can estimate the delivered dose using this particular microCT given the scanning protocol (kVp and mAs) as well as the size of the scanned object.

  5. The estimation of absorbed dose rates for non-human biota : an extended inter-comparison.

    SciTech Connect

    Batlle, J. V. I.; Beaugelin-Seiller, K.; Beresford, N. A.; Copplestone, D.; Horyna, J.; Hosseini, A.; Johansen, M.; Kamboj, S.; Keum, D.-K.; Kurosawa, N.; Newsome, L.; Olyslaegers, G.; Vandenhove, H.; Ryufuku, S.; Lynch, S. V.; Wood, M. D.; Yu, C.

    2011-05-01

    An exercise to compare 10 approaches for the calculation of unweighted whole-body absorbed dose rates was conducted for 74 radionuclides and five of the ICRP's Reference Animals and Plants, or RAPs (duck, frog, flatfish egg, rat and elongated earthworm), selected for this exercise to cover a range of body sizes, dimensions and exposure scenarios. Results were analysed using a non-parametric method requiring no specific hypotheses about the statistical distribution of data. The obtained unweighted absorbed dose rates for internal exposure compare well between the different approaches, with 70% of the results falling within a range of variation of {+-}20%. The variation is greater for external exposure, although 90% of the estimates are within an order of magnitude of one another. There are some discernible patterns where specific models over- or under-predicted. These are explained based on the methodological differences including number of daughter products included in the calculation of dose rate for a parent nuclide; source-target geometry; databases for discrete energy and yield of radionuclides; rounding errors in integration algorithms; and intrinsic differences in calculation methods. For certain radionuclides, these factors combine to generate systematic variations between approaches. Overall, the technique chosen to interpret the data enabled methodological differences in dosimetry calculations to be quantified and compared, allowing the identification of common issues between different approaches and providing greater assurance on the fundamental dose conversion coefficient approaches used in available models for assessing radiological effects to biota.

  6. Estimation of the absorbed dose in radiation-processed food. 4. EPR measurements on eggshell

    SciTech Connect

    Desrosiers, M.F.; Le, F.G. ); Harewood, P.M.; Josephson, E.S. ); Montesalvo, M. )

    1993-09-01

    Fresh whole eggs treated with ionizing radiation for Salmonellae control testing. The eggshell was then removed and examined by electron paramagnetic resonance (EPR) spectroscopy to determine if EPR could be used to (1) distinguish irradiated from unirradiated eggs and (2) assess the absorbed dose. No EPR signals were detected in unirradiated eggs, while strong signals were measurable for more than 200 days after irradiation. Although a number of EPR signals were measured, the most intense resonance (g = 2.0019) was used for dosimetry throughout the study. This signal was observed to increase linearly with dose (up to [approximately]6 kGy), which decayed [approximately]20% within the first 5 days after irradiation and remained relatively constant thereafter. The standard added-dose method was used to assess, retrospectively, the dose to eggs processed at 0.2, 0.7, and 1.4 kGy. Relatively good results were obtained when measurement was made on the day the shell was reirradiated; with this procedure estimates were better for shell processed at the lower doses.

  7. Estimates of absorbed dose in different organs in children treated with radium for skin hemangiomas

    SciTech Connect

    Lundell, M.

    1994-12-01

    Between 1930 and 1959, more than 10,000 infants were treated at Radiumhemmet, Stockholm, with radium ({sup 226}Ra) needles and/or tubes for hemangioma of the skin. Absorbed dose to the brain, eye lenses, parotid glands, thyroid gland, breast enlarge, lungs, stomach, intestine, ovaries, testicles and bone marrow were calculated for each individual. The mean absorbed dose to the different organs ranged from 0.06 to 0.48 Gy. The highest absorbed dose was given to the breast (maximum 47.7 Gy). There was a wide dose range for each organ which was due mainly to differences in the distance between the applicator and the organ. The absorbed dose to all organs decreased on average by 32% during the study period. This was due to a 25% decrease in the treatment time and a change in the distribution of the treatment sites. 17 refs., 4 figs., 4 tabs.

  8. ESR spectroscopy for detecting gamma-irradiated dried vegetables and estimating absorbed doses

    NASA Astrophysics Data System (ADS)

    Kwon, Joong-Ho; Chung, Hyung-Wook; Byun, Myung-Woo

    2000-03-01

    In view of an increasing demand for food irradiation technology, the development of a reliable means of detection for the control of irradiated foods has become necessary. Various vegetable food materials (dried cabbage, carrot, chunggyungchae, garlic, onion, and green onion), which can be legally irradiated in Korea, were subjected to a detection study using ESR spectroscopy. Correlation coefficients ( R2) between absorbed doses (2.5-15 kGy) and their corresponding ESR signals were identified from ESR signals. Pre-established threshold values were successfully applied to the detection of 54 coded unknown samples of dried clean vegetables ( chunggyungchae, Brassica camestris var. chinensis), both non-irradiated and irradiated. The ESR signals of irradiated chunggyungchae decreased over a longer storage time, however, even after 6 months of ambient storage, these signals were still distinguishable from those of non-irradiated samples. The most successful estimates of absorbed dose (5 and 8 kGy) were obtained immediately after irradiation using a quadratic fit with average values of 4.85 and 8.65 kGy being calculated.

  9. Improved estimates of the radiation absorbed dose to the urinary bladder wall.

    PubMed

    Andersson, Martin; Minarik, David; Johansson, Lennart; Mattsson, Sören; Leide-Svegborn, Sigrid

    2014-05-07

    Specific absorbed fractions (SAFs) have been calculated as a function of the content in the urinary bladder in order to allow more realistic calculations of the absorbed dose to the bladder wall. The SAFs were calculated using the urinary bladder anatomy from the ICRP male and female adult reference computational phantoms. The urinary bladder and its content were approximated by a sphere with a wall of constant mass, where the thickness of the wall depended on the amount of urine in the bladder. SAFs were calculated for males and females with 17 different urinary bladder volumes from 10 to 800 mL, using the Monte Carlo computer program MCNP5, at 25 energies of mono-energetic photons and electrons ranging from 10 KeV to 10 MeV. The decay was assumed to be homogeneously distributed in the urinary bladder content and the urinary bladder wall, and the mean absorbed dose to the urinary bladder wall was calculated. The Monte Carlo simulations were validated against measurements made with thermoluminescent dosimeters. The SAFs obtained for a urine volume of 200 mL were compared to the values calculated for the urinary bladder wall using the adult reference computational phantoms. The mean absorbed dose to the urinary wall from (18)F-FDG was found to be 77 µGy/MBq formales and 86 µGy/MBq for females, while for (99m)Tc-DTPA the mean absorbed doses were 80 µGy/MBq for males and 86 µGy/MBq for females. Compared to calculations using a constant value of the SAF from the adult reference computational phantoms, the mean absorbed doses to the bladder wall were 60% higher for (18)F-FDG and 30% higher for (99m)Tc-DTPA using the new SAFs.

  10. An estimate by two methods of thyroid absorbed doses due to BRAVO fallout in several northern Marshall Islands

    SciTech Connect

    Musolino, S.V.; Hull, A.P.; Greenhouse, N.A.

    1997-10-01

    Estimates of the thyroid absorbed doses due to fallout originating from the 1 March 1954 BRAVO thermonuclear test on Bikini Atoll have been made for several inhabited locations in the Northern Marshall Islands. Rongelap, Utirik, Rongerik and Ailinginae Atolls were also inhabited on 1 March 1954, where retrospective thyroid absorbed doses have previously been reconstructed. Current estimates are based primarily on external exposure data, which were recorded shortly after each nuclear test in the Castle Series, and secondarily on soil concentrations of {sup 137}Cs in samples collected in 1978 and 1988, along with aerial monitoring done in 1978. External exposures and {sup 137}Cs Soil concentrations were representative of the atmospheric transport and deposition patterns of the entire Castle Series tests and show that the BRAVO test was the major contributor to fallout exposure during the Castle series and other test series which were carried out in the Marshall Islands. These data have been used as surrogates for fission product radioiodines and telluriums in order to estimate the range of thyroid absorbed doses that may have occurred throughout the Marshall Islands. Dosimetry based on these two sets of estimates agreed within a factor of 4 at the locations where BRAVO was the dominant contributor to the total exposure and deposition. Both methods indicate that thyroid absorbed doses in the range of 1 Gy (100 rad) may have been incurred in some of the northern locations, whereas the doses at southern locations did not significantly exceed levels comparable to those from worldwide fallout. The results of these estimates indicate that a systematic medical survey for thyroid disease should be conducted, and that a more definitive dose reconstruction should be made for all the populated atolls and islands in the Northern Marshall Islands beyond Rongelap, Utirik, Rongerik and Ailinginae, which were significantly contaminated by BRAVO fallout. 30 refs., 2 figs., 10 tabs.

  11. An estimate by two methods of thyroid absorbed doses due to BRAVO fallout in several Northern Marshall Islands.

    PubMed

    Musolino, S V; Greenhouse, N A; Hull, A P

    1997-10-01

    Estimates of the thyroid absorbed doses due to fallout originating from the 1 March 1954 BRAVO thermonuclear test on Bikini Atoll have been made for several inhabited locations in the Northern Marshall Islands. Rongelap, Utirik, Rongerik and Ailinginae Atolls were also inhabited on 1 March 1954, where retrospective thyroid absorbed doses have previously been reconstructed. The current estimates are based primarily on external exposure data, which were recorded shortly after each nuclear test in the Castle Series, and secondarily on soil concentrations of 137Cs in samples collected in 1978 and 1988, along with aerial monitoring done in 1978. The external exposures and 137Cs soil concentrations were representative of the atmospheric transport and deposition patterns of the entire Castle Series tests and show that the BRAVO test was the major contributor to fallout exposure during the Castle series and other test series which were carried out in the Marshall Islands. These data have been used as surrogates for fission product radioiodines and telluriums in order to estimate the range of thyroid absorbed doses that may have occurred throughout the Marshall Islands. Dosimetry based on these two sets of estimates agreed within a factor of 4 at the locations where BRAVO was the dominant contributor to the total exposure and deposition. Both methods indicate that thyroid absorbed doses in the range of 1 Gy (100 rad) may have been incurred in some of the northern locations, whereas the doses at southern locations did not significantly exceed levels comparable to those from worldwide fallout. The results of these estimates indicate that a systematic medical survey for thyroid disease should be conducted, and that a more definitive dose reconstruction should be made for all the populated atolls and islands in the Northern Marshall Islands beyond Rongelap, Utirik, Rongerik and Ailinginae, which were significantly contaminated by BRAVO fallout.

  12. Absorbed dose estimates to structures of the brain and head using a high-resolution voxel-based head phantom.

    PubMed

    Evans, J F; Blue, T E; Gupta, N

    2001-05-01

    The purpose of this article is to demonstrate the viability of using a high-resolution 3-D head phantom in Monte Carlo N-Particle (MCNP) for boron neutron capture therapy (BNCT) structure dosimetry. This work describes a high-resolution voxel-based model of a human head and its use for calculating absorbed doses to the structures of the brain. The Zubal head phantom is a 3-D model of a human head that can be displayed and manipulated on a computer. Several changes were made to the original head phantom which now contains over 29 critical structures of the brain and head. The modified phantom is a 85 x 109 x 120 lattice of voxels, where each voxel is 2.2 x 2.2 x 1.4 mm3. This model was translated into MCNP lattice format. As a proof of principle study, two MCNP absorbed dose calculations were made (left and right lateral irradiations) using a uniformly distributed neutron disk source with an 1/E energy spectrum. Additionally, the results of these two calculations were combined to estimate the absorbed doses from a bilateral irradiation. Radiobiologically equivalent (RBE) doses were calculated for all structures and were normalized to 12.8 Gy-Eq. For a left lateral irradiation, the left motor cortex receives the limiting RBE dose. For a bilateral irradiation, the insula cortices receive the limiting dose. Among the nonencephalic structures, the parotid glands receive RBE doses that were within 15% of the limiting dose.

  13. Absorbed dose estimations of 131I for critical organs using the GEANT4 Monte Carlo simulation code

    NASA Astrophysics Data System (ADS)

    Ziaur, Rahman; Shakeel, ur Rehman; Waheed, Arshed; Nasir, M. Mirza; Abdul, Rashid; Jahan, Zeb

    2012-11-01

    The aim of this study is to compare the absorbed doses of critical organs of 131I using the MIRD (Medical Internal Radiation Dose) with the corresponding predictions made by GEANT4 simulations. S-values (mean absorbed dose rate per unit activity) and energy deposition per decay for critical organs of 131I for various ages, using standard cylindrical phantom comprising water and ICRP soft-tissue material, have also been estimated. In this study the effect of volume reduction of thyroid, during radiation therapy, on the calculation of absorbed dose is also being estimated using GEANT4. Photon specific energy deposition in the other organs of the neck, due to 131I decay in the thyroid organ, has also been estimated. The maximum relative difference of MIRD with the GEANT4 simulated results is 5.64% for an adult's critical organs of 131I. Excellent agreement was found between the results of water and ICRP soft tissue using the cylindrical model. S-values are tabulated for critical organs of 131I, using 1, 5, 10, 15 and 18 years (adults) individuals. S-values for a cylindrical thyroid of different sizes, having 3.07% relative differences of GEANT4 with Siegel & Stabin results. Comparison of the experimentally measured values at 0.5 and 1 m away from neck of the ionization chamber with GEANT4 based Monte Carlo simulations results show good agreement. This study shows that GEANT4 code is an important tool for the internal dosimetry calculations.

  14. Radiobiologic risk estimation from dental radiology. Part I. Absorbed doses to critical organs

    SciTech Connect

    Underhill, T.E.; Chilvarquer, I.; Kimura, K.; Langlais, R.P.; McDavid, W.D.; Preece, J.W.; Barnwell, G.

    1988-07-01

    The aim of the present study was to generate one consistent set of data for evaluating and comparing radiobiologic risks from different dental radiographic techniques. To accomplish this goal, absorbed doses were measured in fourteen anatomic sites from (1) five different panoramic machines with the use of rare-earth screens, (2) a twenty-film complete-mouth survey with E-speed film, long round cone, (3) a twenty-film complete-mouth survey with E-speed film, long rectangular cone, (4) a four-film interproximal survey with E-speed film, long round cone, and (5) a four-film interproximal survey with E-speed film, long rectangular cone. The dose to the thyroid gland, the active bone marrow, the brain, and the salivary glands was evaluated by means of exposure of a tissue-equivalent phantom, fitted with lithium fluoride thermoluminescent dosimeters (TLDs) at the relevant locations.

  15. Accidental embryo irradiation during barium enema examinations: An estimation of absorbed dose

    SciTech Connect

    Damilakis, J.; Perisinakis, K.; Grammatikakis, J.

    1996-04-01

    The purpose of this report is to investigate the possibility of an embryo to receive a dose of more than 10 cGy, the threshold of malformation induction in embryos reported by the International Commission on Radiological Protection, during barium enema examinations. Thermoluminescent dosimeters were place in a phantom to calculate the depth-to-skin conversion coefficient needed for dose estimation at the average embryo depth in patients. Barium enema examinations were performed in 20 women of childbearing age with diagnostic problems demanding longer fluoroscopy times. Doses at 6 cm, the average embryo depth, were determined by measurements at the patients` skin followed by dose calculation at the site of interest. The range of doses estimated at embryo depth for patients was 1.9 to 8.2 cGy. The dose always exceeded 5 cGy when fluoroscopy time was longer than 7 minutes. The dose at the embryo depth never exceeded 10 cGy. This study indicates that fluoroscopy time should not exceed 7 minutes in childbearing-age female patients undergoing barium enema examinations. 6 refs., 1 fig., 2 tabs.

  16. Radiation absorbed dose estimates for oxygen-15 radiopharmaceuticals (H2( V)O, C VO, O VO) in newborn infants

    SciTech Connect

    Powers, W.J.; Stabin, M.; Howse, D.; Eichling, J.O.; Herscovitch, P.

    1988-12-01

    In preparation for measurement of regional cerebral oxygen metabolism by positron emission tomography, radiation absorbed dose estimates for 19 internal organs, blood, and total body were calculated for newborn infants following bolus intravenous administration of H2( V)O and brief inhalation of C VO and O VO. Cumulated activity for each radiopharmaceutical was calculated from a compartmental model based on the known biologic behavior of the compound. Values for mean absorbed dose/unit cumulated activity (S) for internal organs and total body were based on a newborn phantom. S was separately calculated for blood. Total radiopharmaceutical absorbed dose estimates necessary to measure cerebral oxygen metabolism in a 3.51-kg infant based on 0.7 mCi/kg H2( V)O and 1 mCi/kg C VO and O VO were determined to be 1.6 rad to the lung (maximum organ dose), 0.28 rad to the marrow, 0.46 rad to the gonads, and 0.22 rad to total body. These values are similar to those for current clinical nuclear medicine procedures employing /sup 99m/Tc in newborn infants.

  17. Estimation of absorbed dose in clinical radiotherapy linear accelerator beams: Effect of ion chamber calibration and long-term stability.

    PubMed

    Ravichandran, Ramamoorthy; Binukumar, Johnson Pichy; Davis, Cheriyathmanjiyil Antony

    2013-10-01

    The measured dose in water at reference point in phantom is a primary parameter for planning the treatment monitor units (MU); both in conventional and intensity modulated/image guided treatments. Traceability of dose accuracy therefore still depends mainly on the calibration factor of the ion chamber/dosimeter provided by the accredited Secondary Standard Dosimetry Laboratories (SSDLs), under International Atomic Energy Agency (IAEA) network of laboratories. The data related to Nd,water calibrations, thermoluminescent dosimetry (TLD) postal dose validation, inter-comparison of different dosimeter/electrometers, and validity of Nd,water calibrations obtained from different calibration laboratories were analyzed to find out the extent of accuracy achievable. Nd,w factors in Gray/Coulomb calibrated at IBA, GmBH, Germany showed a mean variation of about 0.2% increase per year in three Farmer chambers, in three subsequent calibrations. Another ion chamber calibrated in different accredited laboratory (PTW, Germany) showed consistent Nd,w for 9 years period. The Strontium-90 beta check source response indicated long-term stability of the ion chambers within 1% for three chambers. Results of IAEA postal TL "dose intercomparison" for three photon beams, 6 MV (two) and 15 MV (one), agreed well within our reported doses, with mean deviation of 0.03% (SD 0.87%) (n = 9). All the chamber/electrometer calibrated by a single SSDL realized absorbed doses in water within 0.13% standard deviations. However, about 1-2% differences in absorbed dose estimates observed when dosimeters calibrated from different calibration laboratories are compared in solid phantoms. Our data therefore imply that the dosimetry level maintained for clinical use of linear accelerator photon beams are within recommended levels of accuracy, and uncertainties are within reported values.

  18. Accuracy and optimal timing of activity measurements in estimating the absorbed dose of radioiodine in the treatment of Graves' disease

    NASA Astrophysics Data System (ADS)

    Merrill, S.; Horowitz, J.; Traino, A. C.; Chipkin, S. R.; Hollot, C. V.; Chait, Y.

    2011-02-01

    Calculation of the therapeutic activity of radioiodine 131I for individualized dosimetry in the treatment of Graves' disease requires an accurate estimate of the thyroid absorbed radiation dose based on a tracer activity administration of 131I. Common approaches (Marinelli-Quimby formula, MIRD algorithm) use, respectively, the effective half-life of radioiodine in the thyroid and the time-integrated activity. Many physicians perform one, two, or at most three tracer dose activity measurements at various times and calculate the required therapeutic activity by ad hoc methods. In this paper, we study the accuracy of estimates of four 'target variables': time-integrated activity coefficient, time of maximum activity, maximum activity, and effective half-life in the gland. Clinical data from 41 patients who underwent 131I therapy for Graves' disease at the University Hospital in Pisa, Italy, are used for analysis. The radioiodine kinetics are described using a nonlinear mixed-effects model. The distributions of the target variables in the patient population are characterized. Using minimum root mean squared error as the criterion, optimal 1-, 2-, and 3-point sampling schedules are determined for estimation of the target variables, and probabilistic bounds are given for the errors under the optimal times. An algorithm is developed for computing the optimal 1-, 2-, and 3-point sampling schedules for the target variables. This algorithm is implemented in a freely available software tool. Taking into consideration 131I effective half-life in the thyroid and measurement noise, the optimal 1-point time for time-integrated activity coefficient is a measurement 1 week following the tracer dose. Additional measurements give only a slight improvement in accuracy.

  19. Methods of calculating radiation absorbed dose.

    PubMed

    Wegst, A V

    1987-01-01

    The new tumoricidal radioactive agents being developed will require a careful estimate of radiation absorbed tumor and critical organ dose for each patient. Clinical methods will need to be developed using standard imaging or counting instruments to determine cumulated organ activities with tracer amounts before the therapeutic administration of the material. Standard MIRD dosimetry methods can then be applied.

  20. Estimates of radiation absorbed dose for intraperitoneally administered iodine-131 radiolabeled B72. 3 monoclonal antibody in patients with peritoneal carcinomatoses

    SciTech Connect

    Larson, S.M.; Carrasquillo, J.A.; Colcher, D.C.; Yokoyama, K.; Reynolds, J.C.; Bacharach, S.A.; Raubitchek, A.; Pace, L.; Finn, R.D.; Rotman, M. )

    1991-09-01

    Using a newly available model for determining estimates of radiation absorbed dose of radioisotopes administered intraperitoneally, the authors have calculated absorbed dose to tumor and normal tissues based on a surgically controlled study of radiolabeled antibody distribution. Ten patients with peritoneal carcinomatosis received intraperitoneal injections of the murine monoclonal antibody B72.3 radiolabeled with 131I. Biodistribution studies were performed using nuclear medicine methods until laparotomy at 4-14 days after injection. Surgical biopsies of normal tissues and tumor were obtained. The marrow was predicted to be the critical organ, with maximum tolerated dose (200 rad (2 Gy) to marrow) expected at about 200 mCi (7.4 GBq). In patients with large intraperitoneal tumor deposits, the tumor itself is an important source tissue for radiation exposure to normal tissues. Local hot-spots for tumor-absorbed dose were observed, with maximum tumor-absorbed dose calculated at 11,000 rad (11 Gy) per 100 mCi (3.7 GBq) administered intraperitoneal; however, tumor rad dose varied considerably. This may pose serious problems for curative therapy, especially in patients with large tumor burdens.

  1. Assessment of organ absorbed doses and estimation of effective doses from pediatric anthropomorphic phantom measurements for multi-detector row CT with and without automatic exposure control.

    PubMed

    Brisse, Hervé J; Robilliard, Magalie; Savignoni, Alexia; Pierrat, Noelle; Gaboriaud, Geneviève; De Rycke, Yann; Neuenschwander, Sylvia; Aubert, Bernard; Rosenwald, Jean-Claude

    2009-10-01

    This study was designed to measure organ absorbed doses from multi-detector row computed tomography (MDCT) on pediatric anthropomorphic phantoms, calculate the corresponding effective doses, and assess the influence of automatic exposure control (AEC) in terms of organ dose variations. Four anthropomorphic phantoms (phantoms represent the equivalent of a newborn, 1-, 5-, and 10-y-old child) were scanned with a four-channel MDCT coupled with a z-axis-based AEC system. Two CT torso protocols were compared: a first protocol without AEC and constant tube current-time product and a second protocol with AEC using age-adjusted noise indices. Organ absorbed doses were monitored by thermoluminescent dosimeters (LiF: Mg, Cu, P). Effective doses were calculated according to the tissue weighting factors of the International Commission on Radiological Protection (). For fixed mA acquisitions, organ doses normalized to the volume CT dose index in a 16-cm head phantom (CTDIvol16) ranged from 0.6 to 1.5 and effective doses ranged from 8.4 to 13.5 mSv. For the newborn-equivalent phantom, the AEC-modulated scan showed almost no significant dose variation compared to the fixed mA scan. For the 1-, 5- and 10-y equivalent phantoms, the use of AEC induced a significant dose decrease on chest organs (ranging from 61 to 31% for thyroid, 37 to 21% for lung, 34 to 17% for esophagus, and 39 to 10% for breast). However, AEC also induced a significant dose increase (ranging from 28 to 48% for salivary glands, 22 to 51% for bladder, and 24 to 70% for ovaries) related to the high density of skull base and pelvic bones. These dose increases should be considered before using AEC as a dose optimization tool in children.

  2. [Absorbed doses in dental radiology].

    PubMed

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk.

  3. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetite, Bahia, Brazil

    SciTech Connect

    Pereira, Wagner de S; Kelecom, Alphonse

    2008-08-07

    The uranium mining at Caetite (Uranium Concentrate Unit--URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5x10{sup 3} {mu}Gy y{sup -1} has been used. The derived absorbed dose rate calculated for Tilapia was 2.51x10{sup 0} {mu}Gy y{sup -1}, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  4. Using LiF:Mg,Cu,P TLDs to estimate the absorbed dose to water in liquid water around an {sup 192}Ir brachytherapy source

    SciTech Connect

    Lucas, P. Avilés Aubineau-Lanièce, I.; Lourenço, V.; Vermesse, D.; Cutarella, D.

    2014-01-15

    Purpose: The absorbed dose to water is the fundamental reference quantity for brachytherapy treatment planning systems and thermoluminescence dosimeters (TLDs) have been recognized as the most validated detectors for measurement of such a dosimetric descriptor. The detector response in a wide energy spectrum as that of an{sup 192}Ir brachytherapy source as well as the specific measurement medium which surrounds the TLD need to be accounted for when estimating the absorbed dose. This paper develops a methodology based on highly sensitive LiF:Mg,Cu,P TLDs to directly estimate the absorbed dose to water in liquid water around a high dose rate {sup 192}Ir brachytherapy source. Methods: Different experimental designs in liquid water and air were constructed to study the response of LiF:Mg,Cu,P TLDs when irradiated in several standard photon beams of the LNE-LNHB (French national metrology laboratory for ionizing radiation). Measurement strategies and Monte Carlo techniques were developed to calibrate the LiF:Mg,Cu,P detectors in the energy interval characteristic of that found when TLDs are immersed in water around an{sup 192}Ir source. Finally, an experimental system was designed to irradiate TLDs at different angles between 1 and 11 cm away from an {sup 192}Ir source in liquid water. Monte Carlo simulations were performed to correct measured results to provide estimates of the absorbed dose to water in water around the {sup 192}Ir source. Results: The dose response dependence of LiF:Mg,Cu,P TLDs with the linear energy transfer of secondary electrons followed the same variations as those of published results. The calibration strategy which used TLDs in air exposed to a standard N-250 ISO x-ray beam and TLDs in water irradiated with a standard{sup 137}Cs beam provided an estimated mean uncertainty of 2.8% (k = 1) in the TLD calibration coefficient for irradiations by the {sup 192}Ir source in water. The 3D TLD measurements performed in liquid water were obtained with a

  5. Absorbed Dose and Dose Equivalent Calculations for Modeling Effective Dose

    NASA Technical Reports Server (NTRS)

    Welton, Andrew; Lee, Kerry

    2010-01-01

    While in orbit, Astronauts are exposed to a much higher dose of ionizing radiation than when on the ground. It is important to model how shielding designs on spacecraft reduce radiation effective dose pre-flight, and determine whether or not a danger to humans is presented. However, in order to calculate effective dose, dose equivalent calculations are needed. Dose equivalent takes into account an absorbed dose of radiation and the biological effectiveness of ionizing radiation. This is important in preventing long-term, stochastic radiation effects in humans spending time in space. Monte carlo simulations run with the particle transport code FLUKA, give absorbed and equivalent dose data for relevant shielding. The shielding geometry used in the dose calculations is a layered slab design, consisting of aluminum, polyethylene, and water. Water is used to simulate the soft tissues that compose the human body. The results obtained will provide information on how the shielding performs with many thicknesses of each material in the slab. This allows them to be directly applicable to modern spacecraft shielding geometries.

  6. SU-F-18C-08: A Validation Study of a Commercially Available Software Package's Absorbed Dose Estimates in a Physical Phantom

    SciTech Connect

    Supanich, M; Siegelman, J

    2014-06-15

    Purpose: This study assesses the accuracy of the absorbed dose estimates from CT scans generated by Monte Carlo (MC) simulation using a commercially available radiation dose monitoring software program. Methods: Axial CT studies of an anthropomorphic abdomen phantom with dose bores at a central location and 4 peripheral locations were conducted using a fixed tube current at 120 kV. A 100 mm ion chamber and a 0.6 cc ion chamber calibrated at diagnostic energy levels were used to measure dose in the phantom at each of the 5 dose bore locations. Simulations using the software program's Monte Carlo engine were run using a mathematical model of the anthropomorphic phantom to determine conversion coefficients between the CTDIvol used for the study and the dose at the location of the dose bores. Simulations were conducted using both the software's generic CT beam model and a refined model generated using HVL and bow tie filter profile measurements made on the scanner used for the study. Results: Monte Carlo simulations completed using the generalized beam model differed from the measured conversion factors by an absolute value average of 13.0% and 13.8% for the 100 mm and 0.6 cc ion chamber studies, respectively. The MC simulations using the scanner specific beam model generated conversion coefficients that differed from the CTDIvol to measured dose conversion coefficients by an absolute value average of 7.3% and 7.8% for the 100 mm and 0.6 cc ion chamber cases, respectively. Conclusion: A scanner specific beam model used in MC simulations generates more accurate dose conversion coefficients in an anthropomorphic phantom than those generated with a generalized beam model. Agreement between measured conversion coefficients and simulated values were less than 20% for all positions using the universal beam model.

  7. Comparison of mathematical models for red marrow and blood absorbed dose estimation in the radioiodine treatment of advanced differentiated thyroid carcinoma

    NASA Astrophysics Data System (ADS)

    Miranti, A.; Giostra, A.; Richetta, E.; Gino, E.; Pellerito, R. E.; Stasi, M.

    2015-02-01

    Metastatic and recurrent differentiated thyroid carcinoma is preferably treated with 131I, whose administered activity is limited by red marrow (RM) toxicity, originally correlated by Benua to a blood absorbed dose higher than 2 Gy. Afterward a variety of dosimetric approaches has been proposed. The aim of this work is to compare the results of the Benua formula with the ones of other three blood and RM absorbed dose formulae. Materials and methods have been borrowed by the dosimetric protocol of the Italian Internal Dosimetry group and adapted to the routine of our centre. Wilcoxon t-tests and percentage differences have been applied for comparison purposes. Results are significantly different (p < 0.05) from each other, with an average percentage difference between Benua versus other results of -22%. The dosimetric formula applied to determine blood or RM absorbed dose may contribute significantly to increase heterogeneity in absorbed dose and dose-response results. Standardization should be a major objective.

  8. Estimates of lifetime-absorbed daily doses from the use of personal-care products containing polyacrylamide: a Monte Carlo analysis.

    PubMed

    Van Landingham, Cynthia B; Lawrence, Greg A; Shipp, Annette M

    2004-06-01

    Estimates of the lifetime-absorbed daily dose (LADD) of acrylamide resulting from use of representative personal-care products containing polyacrylamides have been developed. All of the parameters that determine the amount of acrylamide absorbed by an individual vary from one individual to another. Moreover, for some parameters there is uncertainty as to which is the correct or representative value from a range of values. Consequently, the parameters used in the estimation of the LADD of acrylamide from usage of a particular product type (e.g., deodorant, makeup, etc.) were represented by distributions evaluated using Monte Carlo analyses.((1-4)) From these data, distributions of values for key parameters, such as the amount of acrylamide in polyacrylamide, absorption fraction, etc., were defined and used to provide a distribution of LADDs for each personal-care product. The estimated total acrylamide LADD (across all products) for males and females at the median, mean, and 95th percentile of the distribution of individual LADD values were 4.7 x 10(-8), 2.3 x 10(-7), and 7.3 x 10(-7) mg/kg/day for females and 3.6 x 10(-8), 1.7 x 10(-7), and 5.4 x 10(-7) mg/kg/day for males. The ratio of the LADDs to risk-specific dose corresponding to a target risk level of 1 x 10(-5), the acceptable risk level for this investigation, derived using approaches typically used by the FDA, the USEPA, and proposed for use by the European Union (EU) were also calculated. All ratios were well below 1, indicating that all the extra lifetime cancer risk from the use of polyacrylamide-containing personal-care products, in the manner assumed in this assessment, are well below acceptable levels. Even if it were assumed that an individual used all of the products together, the estimated LADD would still provide a dose that was well below the acceptable risk levels.

  9. Radiation dose estimates for radiopharmaceuticals

    SciTech Connect

    Stabin, M.G.; Stubbs, J.B.; Toohey, R.E.

    1996-04-01

    Tables of radiation dose estimates based on the Cristy-Eckerman adult male phantom are provided for a number of radiopharmaceuticals commonly used in nuclear medicine. Radiation dose estimates are listed for all major source organs, and several other organs of interest. The dose estimates were calculated using the MIRD Technique as implemented in the MIRDOSE3 computer code, developed by the Oak Ridge Institute for Science and Education, Radiation Internal Dose Information Center. In this code, residence times for source organs are used with decay data from the MIRD Radionuclide Data and Decay Schemes to produce estimates of radiation dose to organs of standardized phantoms representing individuals of different ages. The adult male phantom of the Cristy-Eckerman phantom series is different from the MIRD 5, or Reference Man phantom in several aspects, the most important of which is the difference in the masses and absorbed fractions for the active (red) marrow. The absorbed fractions for flow energy photons striking the marrow are also different. Other minor differences exist, but are not likely to significantly affect dose estimates calculated with the two phantoms. Assumptions which support each of the dose estimates appears at the bottom of the table of estimates for a given radiopharmaceutical. In most cases, the model kinetics or organ residence times are explicitly given. The results presented here can easily be extended to include other radiopharmaceuticals or phantoms.

  10. Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

    NASA Technical Reports Server (NTRS)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

    1989-01-01

    The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

  11. Absorbed doses from temporomandibular joint radiography

    SciTech Connect

    Brooks, S.L.; Lanzetta, M.L.

    1985-06-01

    Thermoluminescent dosimeters were used in a tissue-equivalent phantom to measure doses of radiation absorbed by various structures in the head when the temporomandibular joint was examined by four different radiographic techniques--the transcranial, transorbital, and sigmoid notch (Parma) projections and the lateral tomograph. The highest doses of radiation occurred at the point of entry for the x-ray beam, ranging from 112 mrad for the transorbital view to 990 mrad for the sigmoid notch view. Only the transorbital projection a radiation dose to the lens of the eye. Of the four techniques evaluated, the lateral tomograph produced the highest doses to the pituitary gland and the bone marrow, while the sigmoid notch radiograph produced the highest doses to the parotid gland.

  12. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for 99mTc-hynic-Tyr3-octreotide Imaging

    PubMed Central

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of 99mTc-hydrazinonicotinamide (hynic)-Tyr3-octreotide as a SPECT radiotracer. 99mTc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of 99mhynic-Tyr3-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results. PMID:27134562

  13. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for (99m)Tc-hynic-Tyr(3)-octreotide Imaging.

    PubMed

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of (99m)Tc-hydrazinonicotinamide (hynic)-Tyr(3)-octreotide as a SPECT radiotracer. (99m)Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of (99m)hynic-Tyr(3)-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results.

  14. Bayesian estimation of dose thresholds

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  15. Space radiation absorbed dose distribution in a human phantom

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  16. Space radiation absorbed dose distribution in a human phantom.

    PubMed

    Badhwar, G D; Atwell, W; Badavi, F F; Yang, T C; Cleghorn, T F

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  17. Monte Carlo estimation of radiation dose in organs of female and male adult phantoms due to FDG-F18 absorbed in the lungs

    NASA Astrophysics Data System (ADS)

    Belinato, Walmir; Santos, William S.; Silva, Rogério M. V.; Souza, Divanizia N.

    2014-03-01

    The determination of dose conversion factors (S values) for the radionuclide fluorodeoxyglucose (18F-FDG) absorbed in the lungs during a positron emission tomography (PET) procedure was calculated using the Monte Carlo method (MCNPX version 2.7.0). For the obtained dose conversion factors of interest, it was considered a uniform absorption of radiopharmaceutical by the lung of a healthy adult human. The spectrum of fluorine was introduced in the input data file for the simulation. The simulation took place in two adult phantoms of both sexes, based on polygon mesh surfaces called FASH and MASH with anatomy and posture according to ICRP 89. The S values for the 22 internal organs/tissues, chosen from ICRP No. 110, for the FASH and MASH phantoms were compared with the results obtained from a MIRD V phantoms called ADAM and EVA used by the Committee on Medical Internal Radiation Dose (MIRD). We observed variation of more than 100% in S values due to structural anatomical differences in the internal organs of the MASH and FASH phantoms compared to the mathematical phantom.

  18. Uncertainty analysis for absorbed dose from a brain receptor imaging agent

    SciTech Connect

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

    1999-01-01

    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 was 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.

  19. Absorbed dose to the fetus during bone scintigraphy

    SciTech Connect

    Hedrick, W.R.; DiSimone, R.N.; Wolf, B.H.; Langer, A.

    1988-07-01

    The authors observed the uptake of radiopharmaceutical and calculated absorbed dose in fetuses of two patients who underwent bone scintigraphy with technetium-99m methylene diphosphonate. Dose estimates per administered activity were 17 mrad/mCi (4.6 microGy/MBq) for an 8-week-old fetus and 9.7 mrad/mCi (2.6 microGy/MBq) for an 18-week-old fetus. Neither fetus demonstrated radionuclide uptake above maternal background levels. The uterine activity showed rapid clearance, with an effective half-life of 12 minutes after reaching a maximum within 1 minute after injection. Major contribution to fetal dose comes from the presence of the radionuclide in the maternal bladder. The authors conclude that bone scintigraphy performed unknowingly in pregnant individuals presents negligible increased risk to the fetus.

  20. Direct MC conversion of absorbed dose to graphite to absorbed dose to water for 60Co radiation.

    PubMed

    Lye, J E; Butler, D J; Franich, R D; Harty, P D; Oliver, C P; Ramanathan, G; Webb, D V; Wright, T

    2013-06-01

    The ARPANSA calibration service for (60)Co gamma rays is based on a primary standard graphite calorimeter that measures absorbed dose to graphite. Measurements with the calorimeter are converted to the absorbed dose to water using the calculation of the ratio of the absorbed dose in the calorimeter to the absorbed dose in a water phantom. ARPANSA has recently changed the basis of this calculation from a photon fluence scaling method to a direct Monte Carlo (MC) calculation. The MC conversion uses an EGSnrc model of the cobalt source that has been validated against water tank and graphite phantom measurements, a step that is required to quantify uncertainties in the underlying interaction coefficients in the MC code. A comparison with the Bureau International des Poids et Mesures (BIPM) as part of the key comparison BIPM.RI(I)-K4 showed an agreement of 0.9973 (53).

  1. Absorbed dose from traversing spherically symmetric, Gaussian radioactive clouds

    SciTech Connect

    Thompson, J.M. ); Poston, J.W. . Dept. of Nuclear Engineering)

    1999-06-01

    If a large radioactive cloud is produced, sampling may require that an airplane traverse the cloud. A method to predict the absorbed dose to the aircrew from penetrating the radioactive cloud is needed. Dose rates throughout spherically symmetric Gaussian clouds of various sizes, and the absorbed doses from traversing the clouds, were calculated. Cloud size is a dominant parameter causing dose to vary by orders of magnitude for a given dose rate measured at some distance. A method to determine cloud size, based on dose rate readings at two or more distances from the cloud center, was developed. This method, however, failed to resolve the smallest cloud sizes from measurements made at 1,000 m to 2,000 m from the cloud center.

  2. Estimating γ-rays dose using computer

    NASA Astrophysics Data System (ADS)

    Al-Rawi, Anis M.; Muslih, Raad M.; Al-Harithy, Rafila S.

    When gum arabic is exposed to γ-rays, a change in its reflection and absorption ability for the different wave lengths is obtained. This change is used for estimating the absorbed γ-rays directly. In the present work we are not concerned with the type of components that are chemically formed as emphasis will only be put on the physical changes. The physical state is taken as a potential chemical change since a molecular damage is accumulated as a result of the dose absorbed. The fortran IV data General (Nova 3) designed for estimating colour measurements was connected to a spectrophotometer that enables measuring the changes in both absorbing and reflecting or even diffusing of light through irradiated materials.

  3. Absorbed dose to water reference dosimetry using solid phantoms in the context of absorbed-dose protocols

    SciTech Connect

    Seuntjens, Jan; Olivares, Marina; Evans, Michael; Podgorsak, Ervin

    2005-09-15

    For reasons of phantom material reproducibility, the absorbed dose protocols of the American Association of Physicists in Medicine (AAPM) (TG-51) and the International Atomic Energy Agency (IAEA) (TRS-398) have made the use of liquid water as a phantom material for reference dosimetry mandatory. In this work we provide a formal framework for the measurement of absorbed dose to water using ionization chambers calibrated in terms of absorbed dose to water but irradiated in solid phantoms. Such a framework is useful when there is a desire to put dose measurements using solid phantoms on an absolute basis. Putting solid phantom measurements on an absolute basis has distinct advantages in verification measurements and quality assurance. We introduce a phantom dose conversion factor that converts a measurement made in a solid phantom and analyzed using an absorbed dose calibration protocol into absorbed dose to water under reference conditions. We provide techniques to measure and calculate the dose transfer from solid phantom to water. For an Exradin A12 ionization chamber, we measured and calculated the phantom dose conversion factor for six Solid Water{sup TM} phantoms and for a single Lucite phantom for photon energies between {sup 60}Co and 18 MV photons. For Solid Water{sup TM} of certified grade, the difference between measured and calculated factors varied between 0.0% and 0.7% with the average dose conversion factor being low by 0.4% compared with the calculation whereas for Lucite, the agreement was within 0.2% for the one phantom examined. The composition of commercial plastic phantoms and their homogeneity may not always be reproducible and consistent with assumed composition. By comparing measured and calculated phantom conversion factors, our work provides methods to verify the consistency of a given plastic for the purpose of clinical reference dosimetry.

  4. Evaluation of absorbed dose in Gadolinium neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Abdullaeva, Gayane; Djuraeva, Gulnara; Kim, Andrey; Koblik, Yuriy; Kulabdullaev, Gairatulla; Rakhmonov, Turdimukhammad; Saytjanov, Shavkat

    2015-02-01

    Gadolinium neutron capture therapy (GdNCT) is used for treatment of radioresistant malignant tumors. The absorbed dose in GdNCT can be divided into four primary dose components: thermal neutron, fast neutron, photon and natural gadolinium doses. The most significant is the dose created by natural gadolinium. The amount of gadolinium at the irradiated region is changeable and depends on the gadolinium delivery agent and on the structure of the location where the agent is injected. To de- fine the time dependence of the gadolinium concentration ρ(t) in the irradiated region the pharmacokinetics of gadolinium delivery agent (Magnevist) was studied at intratumoral injection in mice and intramuscular injection in rats. A polynomial approximation was applied to the experimental data and the influence of ρ(t) on the relative change of the absorbed dose of gadolinium was studied.

  5. Internal absorbed dose estimation by a TLD method for -FDG and comparison with the dose estimates from whole body PET

    NASA Astrophysics Data System (ADS)

    Deloar, Hossain M.; Fujiwara, Takehiko; Shidahara, Miho; Nakamura, Takashi; Yamadera, Akira; Itoh, Masatoshi

    1999-02-01

    The thermoluminescent dosimeter (TLD) method has been proposed as a useful tool for estimating internal radiation absorbed dose in nuclear medicine. An efficient approach to verify the accuracy of the TLD method has been performed in this study. Under the standard protocol for 2-[F-18]fluoro-2-deoxy-D-glucose , whole body PET experiments and simultaneous body surface dose measurements by TLDs were performed on six normal volunteers. By using the body surface dose measured with TLDs, the cumulated activities of nine source organs were estimated with a mathematical unfolding technique for three different initial guesses. The accuracy of the results obtained by the TLD method was investigated by comparison with the actual cumulated activity of the same source organs measured by whole body PET. The cumulated activities of the source organs obtained by the TLD method and whole body PET show a significant correlation (correlation coefficient, , level of confidence, ) with each other. The mean effective doses in this study are obtained from the TLD method and obtained from the whole body PET. Good agreement between the results of the TLD method and whole body PET was observed.

  6. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 MgY for the parotid gland, 0.15 MgY for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field.

  7. Tumor-Absorbed Dose Predicts Progression-Free Survival Following 131I-Tositumomab Radioimmunotherapy

    PubMed Central

    Dewaraja, Yuni K.; Schipper, Matthew J.; Shen, Jincheng; Smith, Lauren B.; Murgic, Jure; Savas, Hatice; Youssef, Ehab; Regan, Denise; Wilderman, Scott J.; Roberson, Peter L.; Kaminski, Mark S.; Avram, Anca M.

    2014-01-01

    The study aimed at identifying patient-specific dosimetric and nondosimetric factors predicting outcome of non-Hodgkin lymphoma patients after 131I-tositumomab radioimmunotherapy for potential use in treatment planning. Methods Tumor-absorbed dose measures were estimated for 130 tumors in 39 relapsed or refractory non-Hodgkin lymphoma patients by coupling SPECT/CT imaging with the Dose Planning Method (DPM) Monte Carlo code. Equivalent biologic effect was calculated to assess the biologic effects of nonuniform absorbed dose including the effects of the unlabeled antibody. Evaluated nondosimetric covariates included histology, presence of bulky disease, and prior treatment history. Tumor level outcome was based on volume shrinkage assessed on follow-up CT. Patient level outcome measures were overall response (OR), complete response (CR), and progression-free survival (PFS), determined from clinical assessments that included PET/CT. Results The estimated mean tumor-absorbed dose had a median value of 275 cGy (range, 94–711 cGy). A high correlation was observed between tracer-predicted and therapy-delivered mean tumor-absorbed doses (P < 0.001; r = 0.85). In univariate tumor-level analysis, tumor shrinkage correlated significantly with almost all of the evaluated dosimetric factors, including equivalent biologic effect. Regression analysis showed that OR, CR, and PFS were associated with the dosimetric factors and equivalent biologic effect. Both mean tumor-absorbed dose (P = 0.025) and equivalent biologic effect (P = 0.035) were significant predictors of PFS whereas none of the nondosimetric covariates were found to be statistically significant factors affecting PFS. The most important finding of the study was that in Kaplan–Meier curves stratified by mean dose, longer PFS was observed in patients receiving mean tumor-absorbed doses greater than 200 cGy than in those receiving 200 cGy or less (median PFS, 13.6 vs. 1.9 mo for the 2 dose groups; log-rank P < 0

  8. Assessment of out-of-field absorbed dose and equivalent dose in proton fields

    SciTech Connect

    Clasie, Ben; Wroe, Andrew; Kooy, Hanne; Depauw, Nicolas; Flanz, Jay; Paganetti, Harald; Rosenfeld, Anatoly

    2010-01-15

    Purpose: In proton therapy, as in other forms of radiation therapy, scattered and secondary particles produce undesired dose outside the target volume that may increase the risk of radiation-induced secondary cancer and interact with electronic devices in the treatment room. The authors implement a Monte Carlo model of this dose deposited outside passively scattered fields and compare it to measurements, determine the out-of-field equivalent dose, and estimate the change in the dose if the same target volumes were treated with an active beam scanning technique. Methods: Measurements are done with a thimble ionization chamber and the Wellhofer MatriXX detector inside a Lucite phantom with field configurations based on the treatment of prostate cancer and medulloblastoma. The authors use a GEANT4 Monte Carlo simulation, demonstrated to agree well with measurements inside the primary field, to simulate fields delivered in the measurements. The partial contributions to the dose are separated in the simulation by particle type and origin. Results: The agreement between experiment and simulation in the out-of-field absorbed dose is within 30% at 10-20 cm from the field edge and 90% of the data agrees within 2 standard deviations. In passive scattering, the neutron contribution to the total dose dominates in the region downstream of the Bragg peak (65%-80% due to internally produced neutrons) and inside the phantom at distances more than 10-15 cm from the field edge. The equivalent doses using 10 for the neutron weighting factor at the entrance to the phantom and at 20 cm from the field edge are 2.2 and 2.6 mSv/Gy for the prostate cancer and cranial medulloblastoma fields, respectively. The equivalent dose at 15-20 cm from the field edge decreases with depth in passive scattering and increases with depth in active scanning. Therefore, active scanning has smaller out-of-field equivalent dose by factors of 30-45 in the entrance region and this factor decreases with depth

  9. Weldon Spring historical dose estimate

    SciTech Connect

    Meshkov, N.; Benioff, P.; Wang, J.; Yuan, Y.

    1986-07-01

    This study was conducted to determine the estimated radiation doses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The dose estimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Dose estimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr.

  10. Absorbed Dose in the Uterus of a Three Months Pregnant Woman Due to 131I

    SciTech Connect

    Vega-Carrillo, Hector Rene; Manzanares-Acuna, Eduardo; Hernandez-Davila, Victor Martin; Arcos-Pichardo, Areli; Barquero, Raquel; Iniguez, M. Pilar

    2006-09-08

    The use of 131I is widely used in diagnostic and treatment of patients. If the patient is pregnant the 131I presence in the thyroid it becomes a source of constant exposition to other organs and the fetus. In this study the absorbed dose in the uterus of a 3 months pregnant woman with 131I in her thyroid gland has been calculated. The dose was determined using Monte Carlo methods in which a detailed model of the woman has been developed. The dose was also calculated using a simple procedure that was refined including the photons' attenuation in the woman organs and body. To verify these results an experiment was carried out using a neck phantom with 131I. Comparing the results it was found that the simple calculation tend to overestimate the absorbed dose, by doing the corrections due to body and organs photon attenuation the dose is 0.14 times the Monte Carlo estimation.

  11. Absorbed Dose in the Uterus of a Three Months Pregnant Woman Due to 131I

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, Héctor René; Manzanares-Acuña, Eduardo; Hernández-Dávila, Víctor Martín; Arcos-Pichardo, Areli; Barquero, Raquel; Iñiguez, M. Pilar

    2006-09-01

    The use of 131I is widely used in diagnostic and treatment of patients. If the patient is pregnant the 131I presence in the thyroid it becomes a source of constant exposition to other organs and the fetus. In this study the absorbed dose in the uterus of a 3 months pregnant woman with 131I in her thyroid gland has been calculated. The dose was determined using Monte Carlo methods in which a detailed model of the woman has been developed. The dose was also calculated using a simple procedure that was refined including the photons' attenuation in the woman organs and body. To verify these results an experiment was carried out using a neck phantom with 131I. Comparing the results it was found that the simple calculation tend to overestimate the absorbed dose, by doing the corrections due to body and organs photon attenuation the dose is 0.14 times the Monte Carlo estimation.

  12. Absorbed dose assessment in newborns during x-ray examinations

    NASA Astrophysics Data System (ADS)

    Taipe, Patricia K.; Berrocal, Mariella J.; Carita, Raúl F.

    2012-02-01

    Often a newborn presents breathing problems during the early days of life, i.e. bronchopneumonia, wich are caused in most of cases, by aspirating a mixture of meconium and amniotic fluid. In these cases, it is necessary to make use of a radiograph, requested by the physician to reach a diagnosis. This paper seeks to evaluate the absorbed doses in neonates undergoing a radiograph. For this reason we try to simulate the real conditions in a X-ray room from Lima hospitals. With this finality we perform a simulation made according a questionnaire related to technical data of X-ray equipment, distance between the source and the neonate, and its position to be irradiated. The information obtained has been used to determine the absorbed dose by infants, using the MCNP code. Finally, the results are compared with reference values of international health agencies.

  13. A portable absorbed dose measuring instrument with gamma discrimination

    NASA Technical Reports Server (NTRS)

    Quam, W. M.; Wilde, W. I.

    1972-01-01

    The characteristics of an electronic instrument for measuring the radiation dose absorbed by tissues are presented. The detector is a sphere of tissue-equivalent plastic with a single wire located on a diameter of the sphere. The electronic circuits and method of operation of the detector are described. Advantages are the small size and easy portability plus ability to selectively measure neutron and gamma plus neutron events.

  14. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

  15. The absorbed dose to blood from blood-borne activity

    NASA Astrophysics Data System (ADS)

    Hänscheid, H.; Fernández, M.; Lassmann, M.

    2015-01-01

    The radiation absorbed dose to blood and organs from activity in the blood is relevant for nuclear medicine dosimetry and for research in biodosimetry. The present study provides coefficients for the average absorbed dose rates to the blood from blood-borne activity for radionuclides frequently used in targeted radiotherapy and in PET diagnostics. The results were deduced from published data for vessel radius-dependent dose rate coefficients and reasonable assumptions on the blood-volume distribution as a function of the vessel radius. Different parts of the circulatory system were analyzed separately. Vessel size information for heart chambers, aorta, vena cava, pulmonary artery, and capillaries was taken from published results of morphometric measurements. The remaining blood not contained in the mentioned vessels was assumed to reside in fractal-like vascular trees, the smallest branches of which are the arterioles or venules. The applied vessel size distribution is consistent with recommendations of the ICRP on the blood-volume distribution in the human. The resulting average absorbed dose rates to the blood per nuclear disintegration per milliliter (ml) of blood are (in 10-11 Gy·s-1·Bq-1·ml) Y-90: 5.58, I-131: 2.49, Lu-177: 1.72, Sm-153: 2.97, Tc-99m: 0.366, C-11: 4.56, F-18: 3.61, Ga-68: 5.94, I-124: 2.55. Photon radiation contributes 1.1-1.2·10-11 Gy·s-1·Bq-1·ml to the total dose rate for positron emitters but significantly less for the other nuclides. Blood self-absorption of the energy emitted by ß-particles in the whole blood ranges from 37% for Y-90 to 80% for Tc-99m. The correspondent values in vascular trees, which are important for the absorbed dose to organs, range from 30% for Y-90 to 82% for Tc-99m.

  16. Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

    SciTech Connect

    Willegaignon, J. Sapienza, M. T.; Coura-Filho, G. B.; Buchpiguel, C. A.; Watanabe, T.; Traino, A. C.

    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 measurements 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

  17. Absorbed dose measurements on LDEF and comparisons with predictions.

    PubMed

    Benton, E V; Frank, A L; Benton, E R; Armstrong, T W; Colborn, B L

    1996-11-01

    The radiation environment on LDEF was monitored by cumulative absorbed dose measurements made with TLDs at different locations and shielding depths. The TLDs were included in four experiments: A0015(a) Biostack, P0004 Seeds in Space and P0006 Linear Energy Transfer Spectrum Measurements at the trailing edge (west side) of the satellite; M0004 Fiber Optics Data Link at the leading edge (east side); and A0015(b) Biostack at the Earth side. The shielding depths varied between 0.48 and 15.4 g/cm2, Al equivalent. Both the directional dependence of trapped protons incident on the satellite and the shielding thickness were reflected in absorbed dose values. The trapped proton anisotropy was measured by TLDs at the east and west sides of LDEF. At the east side doses ranged from 2.10 to 2.58 Gy under shielding of 2.90 to 1.37 g/cm2 (M0004) while on the west side doses ranged from 2.66 to 6.48 Gy under shielding of 15.4 to 0.48 g/cm2 (P0006). The west side doses were more than a factor of two higher, where the vertical shielding thicknesses to space were equal. Other west side doses of 3.04 to 4.49 Gy under shielding of 11.7 to 3.85 g/cm2 (A0015(a)) and 2.91 to 6.64 Gy under shielding of 11.1 to 0.48 g/cm2 (P0004) generally agreed with the P0006 results. The Earth side doses of 2.41 to 3.93 Gy under shielding of 10.0 to 1.66 g cm2 (A0015(b)) were intermediate between the east side and west side doses. Calculations utilizing a model of trapped proton spectra were performed by Watts et al. (1993) and comparisons of dose measurement and calculations may be found in a companion paper (Armstrong et al., 1996).

  18. Absorbed dose measurements on LDEF and comparisons with predictions

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Frank, A. L.; Benton, E. R.; Armstrong, T. W.; Colborn, B. L.

    1996-01-01

    The radiation environment on LDEF was monitored by cumulative absorbed dose measurements made with TLDs at different locations and shielding depths. The TLDs were included in four experiments: A0015(a) Biostack, P0004 Seeds in Space and P0006 Linear Energy Transfer Spectrum Measurements at the trailing edge (west side) of the satellite; M0004 Fiber Optics Data Link at the leading edge (east side); and A0015(b) Biostack at the Earth side. The shielding depths varied between 0.48 and 15.4 g/cm2, Al equivalent. Both the directional dependence of trapped protons incident on the satellite and the shielding thickness were reflected in absorbed dose values. The trapped proton anisotropy was measured by TLDs at the east and west sides of LDEF. At the east side doses ranged from 2.10 to 2.58 Gy under shielding of 2.90 to 1.37 g/cm2 (M0004) while on the west side doses ranged from 2.66 to 6.48 Gy under shielding of 15.4 to 0.48 g/cm2 (P0006). The west side doses were more than a factor of two higher, where the vertical shielding thicknesses to space were equal. Other west side doses of 3.04 to 4.49 Gy under shielding of 11.7 to 3.85 g/cm2 (A0015(a)) and 2.91 to 6.64 Gy under shielding of 11.1 to 0.48 g/cm2 (P0004) generally agreed with the P0006 results. The Earth side doses of 2.41 to 3.93 Gy under shielding of 10.0 to 1.66 g cm2 (A0015(b)) were intermediate between the east side and west side doses. Calculations utilizing a model of trapped proton spectra were performed by Watts et al. (1993) and comparisons of dose measurement and calculations may be found in a companion paper (Armstrong et al., 1996).

  19. Specification of absorbed dose to water using model-based dose calculation algorithms for treatment planning in brachytherapy

    NASA Astrophysics Data System (ADS)

    Carlsson Tedgren, Åsa; Alm Carlsson, Gudrun

    2013-04-01

    Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm-10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from 125I, 169Yb and 192Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1-10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies <20 keV. A choice of an appropriate conversion coefficient Dw, med/Dmed is discussed in terms of the cavity size in relation to the size of important cellular targets. Free radicals from DNA bound water of nanometre dimensions contribute to DNA damage and cell killing and may be the most important water compartment in cells implying use of ratios of mass-collision-stopping powers for converting Dmed into Dw,med.

  20. Specification of absorbed dose to water using model-based dose calculation algorithms for treatment planning in brachytherapy.

    PubMed

    Tedgren, Åsa Carlsson; Carlsson, Gudrun Alm

    2013-04-21

    Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm-10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from (125)I, (169)Yb and (192)Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1-10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies <20 keV. A choice of an appropriate conversion coefficient Dw, med/Dmed is discussed in terms of the cavity size in relation to the size of important cellular targets. Free radicals from DNA bound water of nanometre dimensions contribute to DNA damage and cell killing and may be the most important water compartment in cells implying use of ratios of mass-collision-stopping powers for converting Dmed into Dw,med.

  1. Calculation of the absorbed dose and dose equivalent induced by medium energy neutrons and protons and comparison with experiment

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Bishop, B. L.

    1972-01-01

    Monte Carlo calculations have been carried out to determine the absorbed dose and dose equivalent for 592-MeV protons incident on a cylindrical phantom and for neutrons from 580-MeV proton-Be collisions incident on a semi-infinite phantom. For both configurations, the calculated depth dependence of the absorbed dose is in good agreement with experimental data.

  2. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy.

    PubMed

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-07

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,θ0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380 MeV) was established by interpolating between G-values obtained for Co-60 and 250 kV x-rays.An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength.Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3 mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%.Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%.The combined standard uncertainty in the determination of absorbed dose to water at

  3. Spectral estimators of absorbed photosynthetically active radiation in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

    1985-01-01

    Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a Landsat MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95 percent of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50 percent of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73 percent of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

  4. Spectral estimators of absorbed photosynthetically active radiation in corn canopies

    NASA Technical Reports Server (NTRS)

    Gallo, K. P.; Daughtry, C. S. T.; Bauer, M. E.

    1984-01-01

    Most models of crop growth and yield require an estimate of canopy leaf area index (LAI) or absorption of radiation. Relationships between photosynthetically active radiation (PAR) absorbed by corn canopies and the spectral reflectance of the canopies were investigated. Reflectance factor data were acquired with a LANDSAT MSS band radiometer. From planting to silking, the three spectrally predicted vegetation indices examined were associated with more than 95% of the variability in absorbed PAR. The relationships developed between absorbed PAR and the three indices were evaluated with reflectance factor data acquired from corn canopies planted in 1979 through 1982. Seasonal cumulations of measured LAI and each of the three indices were associated with greater than 50% of the variation in final grain yields from the test years. Seasonal cumulations of daily absorbed PAR were associated with up to 73% of the variation in final grain yields. Absorbed PAR, cumulated through the growing season, is a better indicator of yield than cumulated leaf area index. Absorbed PAR may be estimated reliably from spectral reflectance data of crop canopies.

  5. 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.

  6. Thyroid absorbed dose for people at Rongelap, Utirik, and Sifo on March 1, 1954

    SciTech Connect

    Lessard, E.T.; Miltenberger, R.P.; Conrad, R.A.; Musoline, S.V.; Naidu, J.R.; Moorthy, A.; Schopfer, C.J.

    1985-03-01

    A study was undertaken to reexamine thyroid absorbed dose estimates for people accidentally exposed to fallout at Rongelap, Sifo, and Utirik Islands from the Pacific weapon test known as Operation Castle BRAVO. The study included: (1) reevaluation of radiochemical analysis, to relate results from pooled urine to intake, retention, and excretion functions; (2) analysis of neutron-irradiation studies of archival soil samples, to estimate areal activities of the iodine isotopes; (3) analysis of source term, weather data, and meteorological functions used in predicting atmospheric diffusion and fallout deposition, to estimate airborne concentrations of the iodine isotopes; and (4) reevaluation of radioactive fallout, which contaminated a Japanese fishing vessel in the vicinity of Rongelap Island on March 1, 1954, to determine fallout components. The conclusions of the acute exposure study were that the population mean thyroid absorbed doses were 21 gray (2100 rad) at Rongelap, 6.7 gray (670 rad) at Sifo, and 2.8 gray (280 rad) at Utirik. The overall thyroid cancer risk we estimated was in agreement with results published on the Japanese exposed at Nagasaki and Hiroshima. We now postulate that the major route for intake of fallout was by direct ingestion of food prepared and consumed outdoors. 66 refs., 13 figs., 25 tabs.

  7. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1).

  8. Neutron dose estimation in a zero power nuclear reactor

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  9. Development of a primary standard for absorbed dose from unsealed radionuclide solutions

    NASA Astrophysics Data System (ADS)

    Billas, I.; Shipley, D.; Galer, S.; Bass, G.; Sander, T.; Fenwick, A.; Smyth, V.

    2016-12-01

    Currently, the determination of the internal absorbed dose to tissue from an administered radionuclide solution relies on Monte Carlo (MC) calculations based on published nuclear decay data, such as emission probabilities and energies. In order to validate these methods with measurements, it is necessary to achieve the required traceability of the internal absorbed dose measurements of a radionuclide solution to a primary standard of absorbed dose. The purpose of this work was to develop a suitable primary standard. A comparison between measurements and calculations of absorbed dose allows the validation of the internal radiation dose assessment methods. The absorbed dose from an yttrium-90 chloride (90YCl) solution was measured with an extrapolation chamber. A phantom was developed at the National Physical Laboratory (NPL), the UK’s National Measurement Institute, to position the extrapolation chamber as closely as possible to the surface of the solution. The performance of the extrapolation chamber was characterised and a full uncertainty budget for the absorbed dose determination was obtained. Absorbed dose to air in the collecting volume of the chamber was converted to absorbed dose at the centre of the radionuclide solution by applying a MC calculated correction factor. This allowed a direct comparison of the analytically calculated and experimentally determined absorbed dose of an 90YCl solution. The relative standard uncertainty in the measurement of absorbed dose at the centre of an 90YCl solution with the extrapolation chamber was found to be 1.6% (k  =  1). The calculated 90Y absorbed doses from published medical internal radiation dose (MIRD) and radiation dose assessment resource (RADAR) data agreed with measurements to within 1.5% and 1.4%, respectively. This study has shown that it is feasible to use an extrapolation chamber for performing primary standard absorbed dose measurements of an unsealed radionuclide solution. Internal radiation

  10. A Comparison of Model Calculation and Measurement of Absorbed Dose for Proton Irradiation. Chapter 5

    NASA Technical Reports Server (NTRS)

    Zapp, N.; Semones, E.; Saganti, P.; Cucinotta, F.

    2003-01-01

    With the increase in the amount of time spent EVA that is necessary to complete the construction and subsequent maintenance of ISS, it will become increasingly important for ground support personnel to accurately characterize the radiation exposures incurred by EVA crewmembers. Since exposure measurements cannot be taken within the organs of interest, it is necessary to estimate these exposures by calculation. To validate the methods and tools used to develop these estimates, it is necessary to model experiments performed in a controlled environment. This work is such an effort. A human phantom was outfitted with detector equipment and then placed in American EMU and Orlan-M EVA space suits. The suited phantom was irradiated at the LLUPTF with proton beams of known energies. Absorbed dose measurements were made by the spaceflight operational dosimetrist from JSC at multiple sites in the skin, eye, brain, stomach, and small intestine locations in the phantom. These exposures are then modeled using the BRYNTRN radiation transport code developed at the NASA Langley Research Center, and the CAM (computerized anatomical male) human geometry model of Billings and Yucker. Comparisons of absorbed dose calculations with measurements show excellent agreement. This suggests that there is reason to be confident in the ability of both the transport code and the human body model to estimate proton exposure in ground-based laboratory experiments.

  11. Relative Efficiency of TLD-100 to High Linear Energy Transfer Radiation: Correction to Astronaut Absorbed Dose

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Cash, B. L.; Semones, E. J.; Yasuda, H.; Fujitaka, K.

    1999-01-01

    Response of thermoluminescent detectors (TLD-100) to high linear energy transfer (LET) particles has been studied using helium, carbon, silicon, and iron ions from the Heavy Ion Medical Accelerator at Chiba (Japan), iron ions from the Brookhaven National Laboratory (NY) Alternate Gradient Synchrotron, and 53, 134, 185, and 232 MeV protons from the Loma Linda accelerator. Using the measured relative (to 137Cs) dose efficiency, and measured LET spectra from a tissue equivalent proportional counter (TEPC) on 20 Space Shuttle flights, and 7 Mir flights, the underestimation of absorbed dose by these detectors has been evaluated. The dose underestimation is between 15-20% depending upon the flight inclination and shielding location. This has been confirmed by direct correlation of measured dose by TEPC and TLD-100 at a low shielded location in the Shuttle mid-deck. A comparison of efficiency- LET data with a compilation of similar data from TLD-700, shows that shapes of the two curves are nearly identical, but that the TLD-100 curve is systematically lower by about 13%, and is the major cause of dose underestimation. These results strongly suggest that TLDs used for crew dose estimation be regularly calibrated using heavy ions.

  12. Relative Efficiency of TLD-100 to Linear Energy Transfer Radiation: Correction to Astronaut Absorbed Dose

    NASA Technical Reports Server (NTRS)

    Badhwar, Gautam D.; Cash, B. L.; Semones, E. J.; Yasuda, H.; Fujitaka, K.

    1999-01-01

    Response of thermoluminescent detectors (TLD-100) to high linear energy transfer (LET) particles has been studied using helium, carbon, silicon, and iron ions from the Heavy Ion Medical Accelerator at Chiba (Japan), iron ions from the Brookhaven National Laboratory (NY) Alternate Gradient Synchrotron, and 53, 134, 185, and 232 MeV protons from the Loma Linda accelerator. Using the measured relative (to (137)Cs dose efficiency, and measured LET spectra from a tissue equivalent proportional counter (TEPC) on 20 Space Shuttle flights, and 7 Mir flights, the underestimation of absorbed dose by these detectors has been evaluated. The dose underestimation is between 15-20% depending upon the flight inclination and shielding location. This has been confirmed by direct correlation of measured dose by TEPC and TLD-100 at a low shielded location in the Shuttle mid-deck. A comparison of efficiency- LET data with a compilation of similar data from TLD-700, shows that shapes of the two curves are nearly identical, but that the TLD-100 curve is systematically lower by about 13%, and is the major cause of dose underestimation. These results strongly suggest that TLDs used for crew dose estimation be regularly calibrated using heavy ions.

  13. SADDE (Scaled Absorbed Dose Distribution Evaluator): A code to generate input for VARSKIN

    SciTech Connect

    Reece, W.D.; Miller, S.D.; Durham, J.S.

    1989-01-01

    The VARSKIN computer code has been limited to the isotopes for which the scaled absorbed dose distributions were provided by the Medical Internal Radiation Dose (MIRD) Committee or to data that could be interpolated from isotopes that had similar spectra. This document describes the methodology to calculate the scaled absorbed dose distribution data for any isotope (including emissions by the daughter isotopes) and its implementation by a computer code called SADDE (Scaled Absorbed Dose Distribution Evaluator). The SADDE source code is provided along with input examples and verification calculations. 10 refs., 4 figs.

  14. Direct absorbed dose to water determination based on water calorimetry in scanning proton beam delivery

    SciTech Connect

    Sarfehnia, A.; Clasie, B.; Chung, E.; Lu, H. M.; Flanz, J.; Cascio, E.; Engelsman, M.; Paganetti, H.; Seuntjens, J.

    2010-07-15

    Purpose: The aim of this manuscript is to describe the direct measurement of absolute absorbed dose to water in a scanned proton radiotherapy beam using a water calorimeter primary standard. Methods: The McGill water calorimeter, which has been validated in photon and electron beams as well as in HDR {sup 192}Ir brachytherapy, was used to measure the absorbed dose to water in double scattering and scanning proton irradiations. The measurements were made at the Massachusetts General Hospital proton radiotherapy facility. The correction factors in water calorimetry were numerically calculated and various parameters affecting their magnitude and uncertainty were studied. The absorbed dose to water was compared to that obtained using an Exradin T1 Chamber based on the IAEA TRS-398 protocol. Results: The overall 1-sigma uncertainty on absorbed dose to water amounts to 0.4% and 0.6% in scattered and scanned proton water calorimetry, respectively. This compares to an overall uncertainty of 1.9% for currently accepted IAEA TRS-398 reference absorbed dose measurement protocol. The absorbed dose from water calorimetry agrees with the results from TRS-398 well to within 1-sigma uncertainty. Conclusions: This work demonstrates that a primary absorbed dose standard based on water calorimetry is feasible in scattered and scanned proton beams.

  15. SU-FF-T-390: In-Vivo Prostate Brachytherapy Absorbed Dose Measurements

    SciTech Connect

    Gueye, Paul; Velasco, Carlos; Keppel, Cynthia; Murphy, B; Sinesi, C

    2009-06-01

    Purpose: In-vivo prostate brachytherapy absorbed dosimetrydetector using scintillating fibers. Method and Materials: Five pairs of 85.5 {+-} 0.05 cm long blue shifted scintillating fibers (model BCF-10) with 1 mm{sup 2} cross sectional area were placed in a mixture of gelatin (368.6 {+-} 0.5 grams) and water (3.78 {+-} 0.025 liters) to measured the absorbed dose delivered by a 12 Ci {sup 192}Ir HDR source. The fibers were held by a 7 x 7 cm{sup 2} template grid and optically connected to a 16-channel multianode photomultiplier tube (Hamamatsu, model H6568). Each pair consisted of one fiber 4 mm shorter than the other one to extract the dose by the subtraction method. A dose atlas was used for radiation delivered to the phantom. The plans followed delivered 5 and 7 Gy to a point located 2.0 centimeters away from the central dwelling positions. A total of 32 data points were acquired in a plan to assess the linearity and reproducibility of the measurements.Results: Reproducibility of the data was found to be within 5% and the overall accuracy of the system estimated to be {+-}5.5%. The linearity of the data for all 7 measureddose values (ranging from 0.6 to 7 Gy), gives a slope of 312 counts/Gy with a 1.4% relative deviation. Conclusion: This work indicates the possibility of measuring in real-time the dose effectively delivered to a biological system during prostate brachytherapy treatments. The availability of commercially thin (150 {micro}m) scintillating fibers opens the capability of using such system during clinical treatments (by embedding the fibers within the catheters) with the advantage of performing real-time adjustment of the dose delivery.

  16. Photon extremity absorbed dose and kerma conversion coefficients for calibration geometries.

    PubMed

    Veinot, K G; Hertel, N E

    2007-02-01

    Absorbed dose and dose equivalent conversion coefficients are routinely used in personnel dosimetry programs. These conversion coefficients can be applied to particle fluences or to measured air kerma values to determine appropriate operational monitoring quantities such as the ambient dose equivalent or personal dose equivalent for a specific geometry. For personnel directly handling materials, the absorbed dose to the extremities is of concern. This work presents photon conversion coefficients for two extremity calibration geometries using finger and wrist/arm phantoms described in HPS N13.32. These conversion coefficients have been calculated as a function of photon energy in terms of the kerma and the absorbed dose using Monte Carlo techniques and the calibration geometries specified in HPS N13.32. Additionally, kerma and absorbed dose conversion coefficients for commonly used x-ray spectra and calibration source fields are presented. The kerma values calculated in this work for the x-ray spectra and calibration sources compare well to those listed in HPS N13.32. The absorbed dose values, however, differ significantly for higher energy photons because charged particle equilibrium conditions have not been satisfied for the shallow depth. Thus, the air-kerma-to-dose and exposure-to-dose conversion coefficients for Cs and Co listed in HPS N13.32 overestimate the absorbed dose to the extremities. Applying the conversion coefficients listed in HPS N13.32 for Cs, for example, would result in an overestimate of absorbed dose of 62% for the finger phantom and 55% for the wrist phantom.

  17. The changes in optical absorbance of ZrO2 thin film with the rise of the absorbed dose

    NASA Astrophysics Data System (ADS)

    Abayli, D.; Baydogan, N.

    2016-03-01

    In this study, zirconium oxide (ZrO2) thin film samples prepared by sol-gel method were irradiated using Co-60 radioisotope as gamma source. Then, it was investigated the ionizing effect on optical properties of ZrO2 thin film samples with the rise of the absorbed dose. The changes in the optical absorbance of ZrO2 thin films were determined by using optical transmittance and the reflectance measurements in the range between 190 - 1100 nm obtained from PG Instruments T80 UV-Vis spectrophotometer.

  18. Developing population estimates for dose reconstruction projects

    SciTech Connect

    Beck, D.M. )

    1991-01-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project was established in 1987 to estimate radiation doses that people received from nuclear operations at the Hanford site since 1944. To achieve this objective, demographic information was developed that describes the study population in enough detail to allow researchers to identify potentially exposed groups and the number of people in each of those groups. This type of information is central to most dose reconstruction projects. The purpose of this paper is to detail how historical population estimates can be reconstructed in a reliable manner by comparing results using three different estimation methods.

  19. Collective dose-practical ways to estimate a dose matrix.

    PubMed

    Simmonds, Jane; Sihra, Kamaljit; Bexon, Antony

    2006-06-01

    It has been suggested that collective doses should be presented in the form of a 'dose matrix' giving information on the breakdown of collective dose in space and time and by population group. This paper is an initial attempt to provide such a breakdown by geographic region and time, and to give an idea of associated individual doses for routine discharges to atmosphere. This is done through the use of representative per-caput individual doses but these need to be supplemented by information on the individual doses received by the critical group for a full radiological impact assessment. The results show that it is important to distinguish between the different population groups for up to a few hundred years following the discharge. However, beyond this time the main contribution is from global circulation and this distinction is less important. The majority of the collective dose was found to be delivered at low levels of individual doses; the estimated per-caput dose rates were significantly less than 10(-5) Sv y(-1), a level of dose felt to give rise to a trivial risk to the exposed individual.

  20. Fetal dose estimates for CT pelvimetry

    SciTech Connect

    Moore, M.M.; Shearer, D.R.

    1989-04-01

    Fetal and maternal dose estimates for computed tomographic pelvimetry have been obtained from phantom measurements. Use of routine abdomen imaging techniques may result in localized fetal doses in excess of 13 mGy (1.3 rad). With the use of a low-exposure (40-mAs) technique, it is possible to obtain images of acceptable quality for the necessary measurements. The resulting dose to the fetus is approximately 2.3 mGy (0.23 rad).

  1. Estimated radiation dose from timepieces containing tritium

    SciTech Connect

    McDowell-Boyer, L M

    1980-01-01

    Luminescent timepieces containing radioactive tritium, either in elemental form or incorporated into paint, are available to the general public. The purpose of this study was to estimate potential radiation dose commitments received by the public annually as a result of exposure to tritium which may escape from the timepieces during their distribution, use, repair, and disposal. Much uncertainty is associated with final dose estimates due to limitations of empirical data from which exposure parameters were derived. Maximum individual dose estimates were generally less than 3 ..mu..Sv/yr, but ranged up to 2 mSv under worst-case conditions postulated. Estimated annual collective (population) doses were less than 5 person/Sv per million timepieces distributed.

  2. Estimation of photosynthetically active radiation absorbed at the surface

    NASA Astrophysics Data System (ADS)

    Li, Zhanqing; Moreau, Louis; Cihlar, Josef

    1997-12-01

    This paper presents a validation and application of an algorithm by Li and Moreau [1996] for retrieving photosynthetically active radiation (PAR) absorbed at the surface (APARSFC). APARSFC is a key input to estimating PAR absorbed by the green canopy during photosynthesis. Extensive ground-based and space-borne observations collected during the BOREAS experiment in 1994 were processed, colocated, and analyzed. They include downwelling and upwelling PAR observed at three flux towers, aerosol optical depth from ground-based photometers, and satellite reflectance measurements at the top of the atmosphere. The effects of three-dimensional clouds, aerosols, and bidirectional dependence on the retrieval of APARSFC were examined. While the algorithm is simple and has only three input parameters, the comparison between observed and estimated APARSFC shows a small bias error (<10 W m-2) and moderate random error (36 W m-2 for clear, 61 W m-2 for cloudy). Temporal and/or spatial mismatch between satellite and surface observations is a major cause of the random error, especially when broken clouds are present. The algorithm was subsequently employed to map the distribution of monthly mean APARSFC over the 1000×1000 km2 BOREAS region. Considerable spatial variation is found due to variable cloudiness, forest fires, and nonuniform surface albedo.

  3. 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.

  4. Space Radiation Absorbed Dose Distribution in a Human Phantom Torso

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Yang, T.; Atwell, W.

    2000-01-01

    The flight of a human phantom torso with head that containing active dosimeters at 5 organ sites and 1400 TLDs distributed in 34 1" thick sections is described. Experimental dose rates and quality factors are compared with calculations for shielding distributions at the sites using the Computerized Anatomical Male (CAM) model. The measurements were complemented with those obtained from other instruments. These results have provided the most comprehensive data set to map the dose distribution inside a human and to assess the accuracy of radiation transport models and astronaut radiation risk.

  5. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.

    PubMed

    Renner, F; Wulff, J; Kapsch, R-P; Zink, K

    2015-10-07

    There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as

  6. Response functions for computing absorbed dose to skeletal tissues from neutron irradiation.

    PubMed

    Bahadori, Amir A; Johnson, Perry; Jokisch, Derek W; Eckerman, Keith F; Bolch, Wesley E

    2011-11-07

    Spongiosa in the adult human skeleton consists of three tissues-active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM(50)), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM(50) targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM(50) and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM(50) DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 Me

  7. Absorbed dose-to-water protocol applied to synchrotron-generated x-rays at very high dose rates

    NASA Astrophysics Data System (ADS)

    Fournier, P.; Crosbie, J. C.; Cornelius, I.; Berkvens, P.; Donzelli, M.; Clavel, A. H.; Rosenfeld, A. B.; Petasecca, M.; Lerch, M. L. F.; Bräuer-Krisch, E.

    2016-07-01

    Microbeam radiation therapy (MRT) is a new radiation treatment modality in the pre-clinical stage of development at the ID17 Biomedical Beamline of the European synchrotron radiation facility (ESRF) in Grenoble, France. MRT exploits the dose volume effect that is made possible through the spatial fractionation of the high dose rate synchrotron-generated x-ray beam into an array of microbeams. As an important step towards the development of a dosimetry protocol for MRT, we have applied the International Atomic Energy Agency’s TRS 398 absorbed dose-to-water protocol to the synchrotron x-ray beam in the case of the broad beam irradiation geometry (i.e. prior to spatial fractionation into microbeams). The very high dose rates observed here mean the ion recombination correction factor, k s , is the most challenging to quantify of all the necessary corrections to apply for ionization chamber based absolute dosimetry. In the course of this study, we have developed a new method, the so called ‘current ramping’ method, to determine k s for the specific irradiation and filtering conditions typically utilized throughout the development of MRT. Using the new approach we deduced an ion recombination correction factor of 1.047 for the maximum ESRF storage ring current (200 mA) under typical beam spectral filtering conditions in MRT. MRT trials are currently underway with veterinary patients at the ESRF that require additional filtering, and we have estimated a correction factor of 1.025 for these filtration conditions for the same ESRF storage ring current. The protocol described herein provides reference dosimetry data for the associated Treatment Planning System utilized in the current veterinary trials and anticipated future human clinical trials.

  8. Influence of thyroid volume reduction on absorbed dose in 131I therapy studied by using Geant4 Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Ziaur, Rahman; Sikander, M. Mirza; Waheed, Arshed; Nasir, M. Mirza; Waheed, Ahmed

    2014-05-01

    A simulation study has been performed to quantify the effect of volume reduction on the thyroid absorbed dose per decay and to investigate the variation of energy deposition per decay due to β- and γ-activity of 131I with volume/mass of thyroid, for water, ICRP- and ICRU-soft tissue taken as thyroid material. A Monte Carlo model of the thyroid, in the Geant4 radiation transport simulation toolkit was constructed to compute the β- and γ-absorbed dose in the simulated thyroid phantom for various values of its volume. The effect of the size and shape of the thyroid on energy deposition per decay has also been studied by using spherical, ellipsoidal and cylindrical models for the thyroid and varying its volume in 1-25 cm3 range. The relative differences of Geant4 results for different models with each other and MCNP results lie well below 1.870%. The maximum relative difference among the Geant4 estimated results for water with ICRP and ICRU soft tissues is not more than 0.225%. S-values for ellipsoidal, spherical and cylindrical thyroid models were estimated and the relative difference with published results lies within 3.095%. The absorbed fraction values for beta particles show a good agreement with published values within 2.105% deviation. The Geant4 based simulation results of absorbed fractions for gammas again show a good agreement with the corresponding MCNP and EGS4 results (±6.667%) but have 29.032% higher values than that of MIRD calculated values. Consistent with previous studies, the reduction of the thyroid volume is found to have a substantial effect on the absorbed dose. Geant4 simulations confirm dose dependence on the volume/mass of thyroid in agreement with MCNP and EGS4 computed values but are substantially different from MIRD8 data. Therefore, inclusion of size/mass dependence is indicated for 131I radiotherapy of the thyroid.

  9. Absorbed dose simulations in near-surface regions using high dose rate Iridium-192 sources applied for brachytherapy

    NASA Astrophysics Data System (ADS)

    Moura, E. S.; Zeituni, C. A.; Sakuraba, R. K.; Gonçalves, V. D.; Cruz, J. C.; Júnior, D. K.; Souza, C. D.; Rostelato, M. E. C. M.

    2014-02-01

    Brachytherapy treatment with Iridium-192 high dose rate (HDR) sources is widely used for various tumours and it could be developed in many anatomic regions. Iridium-192 sources are inserted inside or close to the region that will be treated. Usually, the treatment is performed in prostate, gynaecological, lung, breast and oral cavity regions for a better clinical dose coverage compared with other techniques, such as, high energy photons and Cobalt-60 machines. This work will evaluate absorbed dose distributions in near-surface regions around Ir-192 HDR sources. Near-surface dose measurements are a complex task, due to the contribution of beta particles in the near-surface regions. These dose distributions should be useful for non-tumour treatments, such as keloids, and other non-intracavitary technique. For the absorbed dose distribution simulations the Monte Carlo code PENELOPE with the general code penEasy was used. Ir-192 source geometry and a Polymethylmethacrylate (PMMA) tube, for beta particles shield were modelled to yield the percentage depth dose (PDD) on a cubic water phantom. Absorbed dose simulations were realized at the central axis to yield the Ir-192 dose fall-off along central axis. The results showed that more than 99.2% of the absorbed doses (relative to the surface) are deposited in 5 cm depth but with slower rate at higher distances. Near-surface treatments with Ir-192 HDR sources yields achievable measurements and with proper clinical technique and accessories should apply as an alternative for treatment of lesions where only beta sources were used.

  10. Graphite calorimetry for absorbed dose measurements in heavy-ion beams

    NASA Astrophysics Data System (ADS)

    Sakama, M.; Kanai, T.; Fukumura, A.

    In order to sophisticate the radiotherapy high accuracy knowledge of the absorbed dose delivered to the patient is essential The main methods of absolute dosimetry are indicated as follows a Dosimetry by ion chamber b Fricke dosimetry and c Calorimetry The calorimetry is most direct method of dosimetry due to direct measurement of energy deposit in principle and no requirement of information of radiation fields for the calibration Many countries tend to adopt the calorimetry to determine the standard absorbed dose to water and become to be capable of deciding the absorbed dose in precision of about 0 6 for photon and electron beams Despite the recent progress of particle therapy the parameters such as w-value and stopping power ratio for ionization chambers in the particles is not obtained accurately Therefore that causes uncertainty in determination of the absolute dose For this reason we developed a graphite calorimeter to obtain high precision absorbed dose and reduce the uncertainty for various beams When the absorbed dose of 1 Gy is irradiated to the sensitive volume the temperature rise is about 1 4 milliKelvins The performance require the resolution of plus or minus 7 micro Kelvins to measure it in precision of plus or minus 0 5 The stability within several micro Kelvins per minute is necessary to obtain measurable background The miniature glass bead thermistors were embedded in the sensitive volume to perform active control of temperature The resistance change of these thermistors is approximately 0 68 Ohms and 488 micro Ohms at

  11. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G.; Poston, J.W. Sr. )

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No penetration of the radionuclide into the blood vessel was assumed nor was cross fire between the vessel assumed. The results are useful in assessing the dose to blood and blood vessel walls for different nuclear medicine procedures.

  12. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G. ); Poston, J.W. . Dept. of Nuclear Engineering)

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No diffusion of the radionuclide into the blood vessel was assumed nor cross fire between vessel was assumed. Results are useful in assessing the dose in blood and blood vessel walls for different nuclear medicine procedures. 6 refs., 6 figs., 5 tabs.

  13. New absorbed dose measurement with cylindrical water phantoms for multidetector CT

    NASA Astrophysics Data System (ADS)

    Ohno, Takeshi; Araki, Fujio; Onizuka, Ryota; Hioki, Kazunari; Tomiyama, Yuuki; Yamashita, Yusuke

    2015-06-01

    The aim of this study was to develop new dosimetry with cylindrical water phantoms for multidetector computed tomography (MDCT). The ionization measurement was performed with a Farmer ionization chamber at the center and four peripheral points in the body-type and head-type cylindrical water phantoms. The ionization was converted to the absorbed dose using a 60Co absorbed-dose-to-water calibration factor and Monte Carlo (MC) -calculated correction factors. The correction factors were calculated from MDCT (Brilliance iCT, 64-slice, Philips Electronics) modeled with GMctdospp (IMPS, Germany) software based on the EGSnrc MC code. The spectrum of incident x-ray beams and the configuration of a bowtie filter for MDCT were determined so that calculated photon intensity attenuation curves for aluminum (Al) and calculated off-center ratio (OCR) profiles in air coincided with those measured. The MC-calculated doses were calibrated by the absorbed dose measured at the center in both cylindrical water phantoms. Calculated doses were compared with measured doses at four peripheral points and the center in the phantom for various beam pitches and beam collimations. The calibration factors and the uncertainty of the absorbed dose determined using this method were also compared with those obtained by CTDIair (CT dose index in air). Calculated Al half-value layers and OCRs in air were within 0.3% and 3% agreement with the measured values, respectively. Calculated doses at four peripheral points and the centers for various beam pitches and beam collimations were within 5% and 2% agreement with measured values, respectively. The MC-calibration factors by our method were 44-50% lower than values by CTDIair due to the overbeaming effect. However, the calibration factors for CTDIair agreed within 5% with those of our method after correction for the overbeaming effect. Our method makes it possible to directly measure the absorbed dose for MDCT and is more robust and accurate than the

  14. Absorbed XFEL Dose in the Components of the LCLS X-Ray Optics

    SciTech Connect

    Hau-Riege, Stefan

    2010-12-03

    There is great concern that the short, intense XFEL pulse of the LCLS will damage the optics that will be placed into the beam. We have analyzed the extent of the problem by considering the anticipated materials and position of the optical components in the beam path, calculated the absorbed dose as a function of photon energy, and compared these doses with the expected doses required (i) to observe rapid degradation due to thermal fatigue, (ii) to reach the melting temperature, or (iii) to actually melt the material. We list the materials that are anticipated to be placed into the Linac Coherent Light Source (LCLS) x-ray free electron laser (XFEL) beam line, their positions, and the absorbed dose, and compare this dose with anticipated damage thresholds.

  15. Air kerma and absorbed dose standards for reference dosimetry in brachytherapy

    PubMed Central

    2014-01-01

    This article reviews recent developments in primary standards for the calibration of brachytherapy sources, with an emphasis on the currently most common photon-emitting radionuclides. The introduction discusses the need for reference dosimetry in brachytherapy in general. The following section focuses on the three main quantities, i.e. reference air kerma rate, air kerma strength and absorbed dose rate to water, which are currently used for the specification of brachytherapy photon sources and which can be realized with primary standards from first principles. An overview of different air kerma and absorbed dose standards, which have been independently developed by various national metrology institutes over the past two decades, is given in the next two sections. Other dosimetry techniques for brachytherapy will also be discussed. The review closes with an outlook on a possible transition from air kerma to absorbed dose to water-based calibrations for brachytherapy sources in the future. PMID:24814696

  16. Calculation of. beta. -ray absorbed dose rate for /sup 131/I applied to the inflorescence of Tradescantia

    SciTech Connect

    Bingo, K.; Tano, S.; Numakunai, T.; Yoshida, Y.; Yamaguchi, H.

    1981-03-01

    Effects of /sup 131/I applied to the inflorescence on the induction of somatic mutations in Tradescantia stamen hairs were previously investigated, and the doubling dose (activity) was estimated to be 4 nCi. In the present paper, the absorbed dose rate in stamen hairs of Tradescantia for ..beta.. rays from the applied /sup 131/I was calculated. The doubling dose for the /sup 131/I (4 nCi) applied to the inflorescence was estimated to be higher than 0.3 rad (assuming uniform distribution of /sup 131/I on the surface of the buds and assuming that the shape of the buds was a sphere) and lower than 1.0 rad.

  17. Monte Carlo Analysis of Pion Contribution to Absorbed Dose from Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Aghara, S.K.; Battnig, S.R.; Norbury, J.W.; Singleterry, R.C.

    2009-01-01

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV - GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  18. Reconstruction of Absorbed Doses to Fibroglandular Tissue of the Breast of Women undergoing Mammography (1960 to the Present)

    PubMed Central

    Thierry-Chef, Isabelle; Simon, Steven L.; Weinstock, Robert M.; Kwon, Deukwoo; Linet, Martha S.

    2013-01-01

    The assessment of potential benefits versus harms from mammographic examinations as described in the controversial breast cancer screening recommendations of the U.S. Preventive Task Force included limited consideration of absorbed dose to the fibroglandular tissue of the breast (glandular tissue dose), the tissue at risk for breast cancer. Epidemiological studies on cancer risks associated with diagnostic radiological examinations often lack accurate information on glandular tissue dose, and there is a clear need for better estimates of these doses. Our objective was to develop a quantitative summary of glandular tissue doses from mammography by considering sources of variation over time in key parameters including imaging protocols, x-ray target materials, voltage, filtration, incident air kerma, compressed breast thickness, and breast composition. We estimated the minimum, maximum, and mean values for glandular tissue dose for populations of exposed women within 5-year periods from 1960 to the present, with the minimum to maximum range likely including 90% to 95% of the entirety of the dose range from mammography in North America and Europe. Glandular tissue dose from a single view in mammography is presently about 2 mGy, about one-sixth the dose in the 1960s. The ratio of our estimates of maximum to minimum glandular tissue doses for average-size breasts was about 100 in the 1960s compared to a ratio of about 5 in recent years. Findings from our analysis provide quantitative information on glandular tissue doses from mammographic examinations which can be used in epidemiologic studies of breast cancer. PMID:21988547

  19. EXPOSURE RELATED DOSE ESTIMATING MODEL (ERDEM)

    EPA Science Inventory

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

  20. Measurement of absorbed dose during the phantom torso experiment on the International Space Station

    NASA Astrophysics Data System (ADS)

    Semones, E.; Gibbons, F.; Golightly, M.; Weyland, M.; Johnson, A.; Smith, G.; Shelfer, T.; Zapp, N.

    The Phantom Torso Experiment (PTE) was flown on the International Space Station (ISS) during Increment 2 (April-August 2001). The experiment was located in the US Lab module Human Research Facility (HRF) rack. The objective of the passive dosimetry portion of the experiment was to measure spatial distributions of absorbed dose in the 34, 1 inch sections of a modified RandoTM phantom. In each section of the phantom, thermoluminescent detectors (TLDs) were placed at various locations (depths) to provide the spatial measurement. TLDs were also located at several radiosensitive organ locations (brain, thyroid, heart/lung, stomach and colon) and two locations on the surface (skin). Active silicon detectors were also placed at these organ locations to provide time resolved results of the absorbed dose rates. Using these detectors, it is possible to separate the trapped and galactic cosmic ray components of the absorbed dose. The TLD results of the spatial and organ dose measurements will be presented and comparisons of the TLD and silicon detector organ absorbed doses will be made.

  1. Study of Fricke-gel dosimeter calibration for attaining precise measurements of the absorbed dose

    SciTech Connect

    Liosi, Giulia Maria; Benedini, Sara; Giacobbo, Francesca; Mariani, Mario; Gambarini, Grazia; Artuso, Emanuele; Gargano, Marco; Ludwig, Nicola; Carrara, Mauro; Pignoli, Emanuele

    2015-07-01

    A method has been studied for attaining, with good precision, absolute measurements of the spatial distribution of the absorbed dose by means of the Fricke gelatin Xylenol Orange dosimetric system. With this aim, the dose response to subsequent irradiations was analyzed. In fact, the proposed modality is based on a pre-irradiation of each single dosimeter in a uniform field with a known dose, in order to extrapolate a calibration image for a subsequent non-uniform irradiation with an un-known dose to be measured. (authors)

  2. Estimation of Photon Specific Absorbed Fractions in Digimouse Voxel Phantom using Monte Carlo Simulation Code FLUKA

    PubMed Central

    Sinha, A.; Patni, H.K.; Dixit, B.M.; Painuly, N.K.; Singh, N.

    2016-01-01

    Background: Most preclinical studies are carried out on mice. For internal dose assessment of a mouse, specific absorbed fraction (SAF) values play an important role. In most studies, SAF values are estimated using older standard human organ compositions and values for limited source target pairs. Objective: SAF values for monoenergetic photons of energies 15, 50, 100, 500, 1000 and 4000 keV were evaluated for the Digimouse voxel phantom incorporated in Monte Carlo code FLUKA. The organ sources considered in this study were lungs, skeleton, heart, bladder, testis, stomach, spleen, pancreas, liver, kidney, adrenal, eye and brain. The considered target organs were lungs, skeleton, heart, bladder, testis, stomach, spleen, pancreas, liver, kidney, adrenal and brain. Eye was considered as a target organ only for eye as a source organ. Organ compositions and densities were adopted from International Commission on Radiological Protection (ICRP) publication number 110. Results: Evaluated organ masses and SAF values are presented in tabular form. It is observed that SAF values decrease with increasing the source-to-target distance. The SAF value for self-irradiation decreases with increasing photon energy. The SAF values are also found to be dependent on the mass of target in such a way that higher values are obtained for lower masses. The effect of composition is highest in case of target organ lungs where mass and estimated SAF values are found to have larger differences. Conclusion: These SAF values are very important for absorbed dose calculation for various organs of a mouse. PMID:28144589

  3. Depth distribution of absorbed dose on the external surface of Cosmos 1887 biosatellite

    SciTech Connect

    Watts, J.W. Jr.; Parnell, T.A.; Akatov, Yu.A.; Dudkin, V.E.; Kovalev, E.E.; Benton, E.V.; Frank, A.L. |

    1995-03-01

    Significant absorbed dose levels exceeding 1.0 Gy day(exp {minus}1) have been measured on the external surface of the Cosmos 1887 biosatellite as functions of depth in stacks of thin thermoluminescent detectors (TLD`s) made in U.S.S.R. and U.S.A. The dose was found to decrease rapidly with increasing absorber thickness, thereby indicating the presence of intensive fluxes of low-energy particles. Comparison between the U.S.S.R. and U.S.A. results and calculations based on the Vette Model environment are in satisfactory agreement. The major contribution to the dose under thin shielding thickness is shown to be from electrons. The fraction of the dose due to protons and heavier charged particles increases with shielding thickness.

  4. Depth distribution of absorbed dose on the external surface of Cosmos 1887 biosatellite

    NASA Technical Reports Server (NTRS)

    Watts, J. W., Jr.; Parnell, T. A.; Akatov, Yu. A.; Dudkin, V. E.; Kovalev, E. E.; Benton, E. V.; Frank, A. L.

    1995-01-01

    Significant absorbed dose levels exceeding 1.0 Gy day(exp -1) have been measured on the external surface of the Cosmos 1887 biosatellite as functions of depth in stacks of thin thermoluminescent detectors (TLD's) made in U.S.S.R. and U.S.A. The dose was found to decrease rapidly with increasing absorber thickness, thereby indicating the presence of intensive fluxes of low-energy particles. Comparison between the U.S.S.R. and U.S.A. results and calculations based on the Vette Model environment are in satisfactory agreement. The major contribution to the dose under thin shielding thickness is shown to be from electrons. The fraction of the dose due to protons and heavier charged particles increases with shielding thickness.

  5. MCNP simulation of absorbed energy and dose by iodinated contrast agent

    NASA Astrophysics Data System (ADS)

    He, Wenjun; Mah, Eugene; Huda, Walter; Yao, Hai

    2012-03-01

    The purpose of this study is to investigate the absorbed dose and energy by iodinated contrast medium in diagnostic radiology. A simulation geometry in which an inner sphere (d = 0.2cm, 1cm, 5cm) filled with iodinated contrast medium (or water) is located at the center of a 20cm diameter water sphere was used in simulations performed with MCNP5 codes. Monoenergetic x-rays with energies ranging from 40 to 80keV from a cone beam source were utilized and contrast medium concentration ranged from 100 to 1mg/ml. Absorbed dose ratio (RD) to inner sphere and total absorbed energies ratio (RE) to the whole phantom with and without iodinated contrast medium were investigated. The maximum RD was ~13 for the 0.2cm diameter sphere with 100mg/ml contrast medium. The maximum RE was ~1.05 for the 5cm diameter contrast sphere at 80keV with 100mg/ml contrast medium. Under the same incident photon energy, increasing the inner sphere size from 0.2cm to 5cm caused a ~63% increase in the RD on average. Decreasing the contrast medium concentration from 100 to 10 mg/ml caused a decrease of RD of ~ 76%. A conclusion was reached that although local absorbed dose increase caused by iodinated contrast agent could be high; the increase in total absorbed energy is negligible.

  6. Diamond detector in absorbed dose measurements in high-energy linear accelerator photon and electron beams.

    PubMed

    Ravichandran, Ramamoorthy; Binukumar, John Pichy; Al Amri, Iqbal; Davis, Cheriyathmanjiyil Antony

    2016-03-08

    Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue-equivalent properties. We investigated a commercially available 'microdiamond' detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1mm, thickness 1 x10(-3) mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17% (1 SD) (n = 11). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stop-ping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long-term stability and reproducibility. Based on micro-dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance.

  7. Dose estimates from the Chernobyl accident

    SciTech Connect

    Lange, R.; Dickerson, M.H.; Gudiksen, P.H.

    1987-11-01

    The Lawrence Livermore National Laboratory Atmospheric Release Advisory Capability (ARAC) responded to the Chernobyl nuclear reactor accident in the Soviet Union by utilizing long-range atmospheric dispersion modeling to estimate the amount of radioactivity released (source term) and the radiation dose distribution due to exposure to the radioactive cloud over Europe and the Northern Hemisphere. In later assessments, after the release of data on the accident by the Soviet Union, the ARAC team used their mesoscale to regional scale model to focus in on the radiation dose distribution within the Soviet Union and the vicinity of the Chernobyl plant. 22 refs., 5 figs., 5 tabs.

  8. Measurements and calculations of the absorbed dose distribution around a 60Co source.

    PubMed

    Tiourina, T B; Dries, W J; van der Linden, P M

    1995-05-01

    The data from Meisberger et al. [Radiology 90, 953-957 (1968)] are often used as a basis for dose calculations in brachytherapy. In order to describe the absorbed dose in water around a brachytherapy point source, Meisberger provided a polynomial fit for different isotopes taking into account the effect of attenuation and scattering. The validity of the Meisberger coefficients is restricted to distances up to 10 cm from the source, which is regarded to be satisfactory for most brachytherapy applications. However, for more distant organs it may lead to errors in calculated absorbed dose. For this reason dose measurements have been performed in air and in water around a high activity 60Co source used in high dose rate brachytherapy. Measurements were carried out to distances of 20 cm, using ionization chambers. These data show that at a distance of about 15 cm the amount of scattered radiation virtually equals the amount of primary radiation. This emphasizes the contribution of scattered radiation to the dose in healthy tissue far from the target volume, even with relatively high energy photon radiation of 60Co. It is also shown that the Meisberger data as well as the approach of Van Kleffens and Star [Int. J. Radiat. Oncol. Phys. 5, 557-563 (1979)] lead to significant errors in absorbed dose between distances of 10 and 20 cm from the source. In addition to these measurements, the Monte Carlo code has been used to calculate separately primary dose and scattered dose from a cobalt point source. The calculated results agree with the experimental data within 1% for a most distant dose scoring region.

  9. Absorbed dose rates in tissue from prompt gamma emissions from near-thermal neutron absorption

    DOE PAGES

    Schwahn, Scott O.

    2015-10-01

    Prompt gamma emission data from the International Atomic Energy Agency s Prompt Gamma-ray Neutron Activation Analysis database are analyzed to determine the absorbed dose rates in tissue to be expected when natural elements are exposed in a near-thermal neutron environment.

  10. Absorbed dose dependence of the correction factors for ionization chamber cable irradiation effects.

    PubMed

    Campos, L L; Caldas, L V

    1991-03-01

    A simple method was developed, for possible use by hospital physicists, to evaluate the irradiation effects on cables and connectors during large-radiation-field dosimetry with ionization chambers and to determine correction factors for the used system or geometry. This method was based on the absorbed dose dependence of the correction factor.

  11. Estimation of RF energy absorbed in the brain from mobile phones in the Interphone Study

    PubMed Central

    Varsier, N; Bowman, J D; Deltour, I; Figuerola, J; Mann, S; Moissonnier, M; Taki, M; Vecchia, P; Villegas, R; Vrijheid, M; Wake, K; Wiart, J

    2011-01-01

    Objectives The objective of this study was to develop an estimate of a radio frequency (RF) dose as the amount of mobile phone RF energy absorbed at the location of a brain tumour, for use in the Interphone Epidemiological Study. Methods We systematically evaluated and quantified all the main parameters thought to influence the amount of specific RF energy absorbed in the brain from mobile telephone use. For this, we identified the likely important determinants of RF specific energy absorption rate during protocol and questionnaire design, we collected information from study subjects, network operators and laboratories involved in specific energy absorption rate measurements and we studied potential modifiers of phone output through the use of software-modified phones. Data collected were analysed to assess the relative importance of the different factors, leading to the development of an algorithm to evaluate the total cumulative specific RF energy (in joules per kilogram), or dose, absorbed at a particular location in the brain. This algorithm was applied to Interphone Study subjects in five countries. Results The main determinants of total cumulative specific RF energy from mobile phones were communication system and frequency band, location in the brain and amount and duration of mobile phone use. Though there was substantial agreement between categorisation of subjects by cumulative specific RF energy and cumulative call time, misclassification was non-negligible, particularly at higher frequency bands. Factors such as adaptive power control (except in Code Division Multiple Access networks), discontinuous transmission and conditions of phone use were found to have a relatively minor influence on total cumulative specific RF energy. Conclusions While amount and duration of use are important determinants of RF dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain. It is important to take

  12. Verification of absorbed dose using diodes in cobalt-60 radiation therapy.

    PubMed

    Gadhi, Muhammad Asghar; Fatmi, Shahab; Chughtai, Gul M; Arshad, Muhammad; Shakil, Muhammad; Rahmani, Uzma Mahmood; Imran, Malik Younas; Buzdar, Saeed Ahmad

    2016-03-01

    The objective of this work was to enhance the quality and safety of dose delivery in the practice of radiation oncology. To achieve this goal, the absorbed dose verification program was initiated by using the diode in vivo dosimetry (IVD) system (for entrance and exit). This practice was implemented at BINO, Bahawalpur, Pakistan. Diodes were calibrated for making absorbed dose measurements. Various correction factors (SSD, dose non-linearity, field size, angle of incidence, and wedge) were determined for diode IVD system. The measurements were performed in phantom in order to validate the IVD procedure. One hundred and nineteen patients were monitored and 995 measurements were performed. For phantom, the percentage difference between measured and calculated dose for entrance setting remained within ±2% and for exit setting ±3%. For patient measurements, the percentage difference between measured and calculated dose remained within ±5% for entrance/open fields and ±7% for exit/wedge/oblique fields. One hundred and nineteen patients and 995 fields have been monitored during the period of 6 months. The analysis of all available measurements gave a mean percent deviation of ±1.19% and standard deviation of ±2.87%. Larger variations have been noticed in oblique, wedge and exit measurements. This investigation revealed that clinical dosimetry using diodes is simple, provides immediate results and is a useful quality assurance tool for dose delivery. It has enhanced the quality of radiation dose delivery and increased/improved the reliability of the radiation therapy practice in BINO.

  13. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow

    SciTech Connect

    Ichimaru, M.; Ishimaru, T.; Mikami, M.; Matsunaga, M.

    1982-08-01

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimated risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure.

  14. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow.

    PubMed

    Ichimaru, M; Ishimaru, T; Mikami, M; Matsunaga, M

    1982-08-01

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimated risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure.

  15. Electron absorbed fractions and dose conversion factors for marrow and bone by skeletal regions

    SciTech Connect

    Eckerman, K.F.; Stabin, M.G.

    2000-02-01

    The possible inductions of bone cancer and leukemia are the two health effects of primary concern in the irradiation of the skeleton. The relevant target tissues to consider in the dosimetric evaluation have been the cells on or near endosteal surfaces of bone, from which osteosarcomas are thought to arise, and hematopoietic bone marrow, which is associated with leukemia. The complex geometry of the soft tissue-bone intermixture makes calculations of absorbed doses to these target regions a difficult problem. In the case of photon or neutron radiations, charged particle equilibrium may not exist in the vicinity of a soft tissue-bone mineral interface. In this paper, absorbed fraction data are developed for calculations of the dose in the target tissues from electron emitters deposited within the volume or on the surfaces of trabecular bone. The skeletal average absorbed fractions presented are consistent with usage of this quantity in the contemporary dosimetric formulations of the International Commission on Radiological Protection (ICRP). Implementation of the new bone and marrow model is then developed within the context of the calculational schema of the Medical Internal Radiation Dose (MIRD) Committee. Model parameters relevant to the calculation of dose conversion factors (S values) for different regions of the skeleton of individuals of various age are described, and an example calculation is performed for a monoclonal antibody which localizes in the marrow. The utility of these calculations for radiation dose calculations in nuclear medicine is discussed.

  16. Absorbed dose measurements on external surface of Kosmos-satellites with glass thermoluminescent detectors.

    PubMed

    Akatov YuA; Arkhangelsky, V V; Kovalev, E E; Spurny, F; Votochkova, I

    1989-01-01

    In this paper we present absorbed dose measurements with glass thermoluminescent detectors on external surface of satellites of Kosmos-serie flying in 1983-87. Experiments were performed with thermoluminescent aluminophosphate glasses of thicknesses 0.1, 0.3, 0.4, 0.5, and 1 mm. They were exposed in sets of total thickness between 5 and 20 mm, which were protected against sunlight with thin aluminized foils. In all missions, extremely high absorbed dose values were observed in the first layers of detectors, up to the thickness of 0.2 to 0.5 gcm-2. These experimental results confirm that, during flights at 250 to 400 km, doses on the surface of the satellites are very high, due to the low energy component of the proton and electron radiation.

  17. Uneven surface absorbed dose distribution in electron-accelerator irradiation of rubber items

    SciTech Connect

    Gorbunov, I.F.; Pashinin, V.I.; Vanyushkin, B.M.

    1988-02-01

    Electron accelerators for industrial use are equipped with scanning devices, where the scan frequency or linear velocity along the window may vary. In a flow technology, where the items are transported to the irradiation zone at a set rate, the speed of an item may be comparable with the scan speed, so there is substantial nonuniformity in the absorbed dose, which adversely affects the quality. We have examined the dose nonuniformity for long rubber items during vulcanization by means of LUE-8-5RV and ELV-2 accelerators. The absorbed dose is calculated for an elementary part along which the irradiation is uniform on the assumption that current density distribution in the unswept beam is uniform as a result of scattering in the foil.

  18. Pain and Mean Absorbed Dose to the Pubic Bone After Radiotherapy Among Gynecological Cancer Survivors

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Al-Abany, Massoud; Palm, Asa; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2011-07-15

    Purpose: To analyze the relationship between mean absorbed dose to the pubic bone after pelvic radiotherapy for gynecological cancer and occurrence of pubic bone pain among long-term survivors. Methods and Materials: In an unselected, population-based study, we identified 823 long-term gynecological cancer survivors treated with pelvic radiotherapy during 1991-2003. For comparison, we used a non-radiation-treated control population of 478 matched women from the Swedish Population Register. Pain, intensity of pain, and functional impairment due to pain in the pubic bone were assessed with a study-specific postal questionnaire. Results: We analyzed data from 650 survivors (participation rate 79%) with median follow-up of 6.3 years (range, 2.3-15.0 years) along with 344 control women (participation rate, 72 %). Ten percent of the survivors were treated with radiotherapy; ninety percent with surgery plus radiotherapy. Brachytherapy was added in 81%. Complete treatment records were recovered for 538/650 survivors, with dose distribution data including dose-volume histograms over the pubic bone. Pubic bone pain was reported by 73 survivors (11%); 59/517 (11%) had been exposed to mean absorbed external beam doses <52.5 Gy to the pubic bone and 5/12 (42%) to mean absorbed external beam doses {>=}52.5 Gy. Thirty-three survivors reported pain affecting sleep, a 13-fold increased prevalence compared with control women. Forty-nine survivors reported functional impairment measured as pain walking indoors, a 10-fold increased prevalence. Conclusions: Mean absorbed external beam dose above 52.5 Gy to the pubic bone increases the occurrence of pain in the pubic bone and may affect daily life of long-term survivors treated with radiotherapy for gynecological cancer.

  19. Dose to medium versus dose to water as an estimator of dose to sensitive skeletal tissue

    NASA Astrophysics Data System (ADS)

    Walters, B. R. B.; Kramer, R.; Kawrakow, I.

    2010-08-01

    The purpose of this study is to determine whether dose to medium, Dm, or dose to water, Dw, provides a better estimate of the dose to the radiosensitive red bone marrow (RBM) and bone surface cells (BSC) in spongiosa, or cancellous bone. This is addressed in the larger context of the ongoing debate over whether Dm or Dw should be specified in Monte Carlo calculated radiotherapy treatment plans. The study uses voxelized, virtual human phantoms, FAX06/MAX06 (female/male), incorporated into an EGSnrc Monte Carlo code to perform Monte Carlo dose calculations during simulated irradiation by a 6 MV photon beam from an Elekta SL25 accelerator. Head and neck, chest and pelvis irradiations are studied. FAX06/MAX06 include precise modelling of spongiosa based on µCT images, allowing dose to RBM and BSC to be resolved from the dose to bone. Modifications to the FAX06/MAX06 user codes are required to score Dw and Dm in spongiosa. Dose uncertainties of ~1% (BSC, RBM) or ~0.5% (Dm, Dw) are obtained after up to 5 days of simulations on 88 CPUs. Clinically significant differences (>5%) between Dm and Dw are found only in cranial spongiosa, where the volume fraction of trabecular bone (TBVF) is high (55%). However, for spongiosa locations where there is any significant difference between Dm and Dw, comparisons of differential dose volume histograms (DVHs) and average doses show that Dw provides a better overall estimate of dose to RBM and BSC. For example, in cranial spongiosa the average Dm underestimates the average dose to sensitive tissue by at least 5%, while average Dw is within ~1% of the average dose to sensitive tissue. Thus, it is better to specify Dw than Dm in Monte Carlo treatment plans, since Dw provides a better estimate of dose to sensitive tissue in bone, the only location where the difference is likely to be clinically significant.

  20. Dose Estimation in Pediatric Nuclear Medicine.

    PubMed

    Fahey, Frederic H; Goodkind, Alison B; Plyku, Donika; Khamwan, Kitiwat; O'Reilly, Shannon E; Cao, Xinhua; Frey, Eric C; Li, Ye; Bolch, Wesley E; Sgouros, George; Treves, S Ted

    2017-03-01

    The practice of nuclear medicine in children is well established for imaging practically all physiologic systems but particularly in the fields of oncology, neurology, urology, and orthopedics. Pediatric nuclear medicine yields images of physiologic and molecular processes that can provide essential diagnostic information to the clinician. However, nuclear medicine involves the administration of radiopharmaceuticals that expose the patient to ionizing radiation and children are thought to be at a higher risk for adverse effects from radiation exposure than adults. Therefore it may be considered prudent to take extra care to optimize the radiation dose associated with pediatric nuclear medicine. This requires a solid understanding of the dosimetry associated with the administration of radiopharmaceuticals in children. Models for estimating the internal radiation dose from radiopharmaceuticals have been developed by the Medical Internal Radiation Dosimetry Committee of the Society of Nuclear Medicine and Molecular Imaging and other groups. But to use these models accurately in children, better pharmacokinetic data for the radiopharmaceuticals and anatomical models specifically for children need to be developed. The use of CT in the context of hybrid imaging has also increased significantly in the past 15 years, and thus CT dosimetry as it applies to children needs to be better understood. The concept of effective dose has been used to compare different practices involving radiation on a dosimetric level, but this approach may not be appropriate when applied to a population of children of different ages as the radiosensitivity weights utilized in the calculation of effective dose are not specific to children and may vary as a function of age on an organ-by-organ bias. As these gaps in knowledge of dosimetry and radiation risk as they apply to children are filled, more accurate models can be developed that allow for better approaches to dose optimization. In turn, this

  1. Radiation absorbed doses from iron-52, iron-55, and iron-59 used to study ferrokinetics

    SciTech Connect

    Robertson, J.S.; Price, R.R.; Budinger, T.F.; Fairbanks, V.F.; Pollycove, M.

    1983-04-01

    Biological data obtained principally with Fe-59 citrate are used with physical data to calculate radiation absorbed doses for ionic or weak chelate forms of Fe-52, Fe-55, and Fe-59, administered by intravenous injection. Doses are calculated for normal subjects, primary hemochromatosis (also called idiopathic or hereditary hemochromatosis), pernicious anemia in relapse, iron-deficiency anemia, and polycythemia vera. The Fe-52 doses include the dose from the Mn-52m daughter generated after injection of Fe-52. Special attention has been given to the dose to the spleen, which has a relatively high concentration of RBCs and therefore of radioiron, and which varies significantly in size in both health and disease.

  2. Microdosimetric measurements for neutron-absorbed dose determination during proton therapy

    PubMed Central

    Pérez-Andújar, Angélica; DeLuca, Paul M.; Thornton, Allan F.; Fitzek, Markus; Hecksel, Draik; Farr, Jonathan

    2012-01-01

    This work presents microdosimetric measurements performed at the Midwest Proton Radiotherapy Institute in Bloomington, Indiana, USA. The measurements were done simulating clinical setups with a water phantom and for a variety of stopping targets. The water phantom was irradiated by a proton spread out Bragg peak (SOBP) and by a proton pencil beam. Stopping target measurements were performed only for the pencil beam. The targets used were made of polyethylene, brass and lead. The objective of this work was to determine the neutron-absorbed dose for a passive and active proton therapy delivery, and for the interactions of the proton beam with materials typically in the beam line of a proton therapy treatment nozzle. Neutron doses were found to be higher at 45° and 90° from the beam direction for the SOBP configuration by a factor of 1.1 and 1.3, respectively, compared with the pencil beam. Meanwhile, the pencil beam configuration produced neutron-absorbed doses 2.2 times higher at 0° than the SOBP. For stopping targets, lead was found to dominate the neutron-absorbed dose for most angles due to a large production of low-energy neutrons emitted isotropically. PMID:22334761

  3. Absorbed Dose Determination Using Experimental and Analytical Predictions of X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Edwards, D. L.; Carruth, Ralph (Technical Monitor)

    2001-01-01

    Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the U.S. Space Shuttle. This series of experiments was named the international space welding experiment (ISWE). The hardware associated with the ISWE was leased to NASA by the Paton Welding Institute (PWI) in Ukraine for ground-based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used thermoluminescence dosimeters (TLD's) shielded with material currently used by astronauts during extravehicular activities to measure the radiation dose. The TLD's were exposed to x-ray radiation generated by operation of the ISWE in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure, then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the ISWE in-vacuum electron beam welding tool. The calculated absorbed dose

  4. An international dosimetry exchange for boron neutron capture therapy. Part I: Absorbed dose measurements.

    PubMed

    Binns, P J; Riley, K J; Harling, O K; Kiger, W S; Munck af Rosenschöld, P M; Giusti, V; Capala, J; Sköld, K; Auterinen, I; Serén, T; Kotiluoto, P; Uusi-Simola, J; Marek, M; Viererbl, L; Spurny, F

    2005-12-01

    An international collaboration was organized to undertake a dosimetry exchange to enable the future combination of clinical data from different centers conducting neutron capture therapy trials. As a first step (Part I) the dosimetry group from the Americas, represented by MIT, visited the clinical centers at Studsvik (Sweden), VTT Espoo (Finland), and the Nuclear Research Institute (NRI) at Rez (Czech Republic). A combined VTT/NRI group reciprocated with a visit to MIT. Each participant performed a series of dosimetry measurements under equivalent irradiation conditions using methods appropriate to their clinical protocols. This entailed in-air measurements and dose versus depth measurements in a large water phantom. Thermal neutron flux as well as fast neutron and photon absorbed dose rates were measured. Satisfactory agreement in determining absorbed dose within the experimental uncertainties was obtained between the different groups although the measurement uncertainties are large, ranging between 3% and 30% depending upon the dose component and the depth of measurement. To improve the precision in the specification of absorbed dose amongst the participants, the individually measured dose components were normalized to the results from a single method. Assuming a boron concentration of 15 microg g(-1) that is typical of concentrations realized clinically with the boron delivery compound boronophenylalanine-fructose, systematic discrepancies in the specification of the total biologically weighted dose of up to 10% were apparent between the different groups. The results from these measurements will be used in future to normalize treatment plan calculations between the different clinical dosimetry protocols as Part II of this study.

  5. Radioimmunotherapy treatment planning based on radiation absorbed dose or patient size

    SciTech Connect

    Eary, J.F.; Krohn, K.A.; Press, O.W. |

    1996-05-01

    Several approaches have been used to plan treatment doses for patients undergoing radioimmunotherapy. Investigators often use fixed doses, or doses based on patient size (mCi/kg or mCi/m{sup 2}). Our treatment protocols for lymphoma and leukemia involved calculation of tissue radiation absorbed dose based on images from a trace labeled infusion of antibody prior to treatment. In a recent analysis of patients treated in the Phase I and II dose escalation trial for treatment of non-Hodgkin`s lymphoma with I-131 anti-CD20 antibody (B1), we investigated the relationship between our dosimetry based treatment and dose based on patient size. Tissue radiation dose for several normal organs and for tumors were plotted versus the mCi administered per kg or m{sup 2} of the patient to evaluate the relationship between the two treatment approaches. These graphs showed correlation coefficients ranging from 0.021 to 0.684, demonstrating the variability in antibody catabolism between patients. This means that fixed doses or administrations based on patient size do not deliver consistent radiation doses to normal organs or tumors. This finding was extrapolated to show that toxicity from doses based on patient size di not correlate with treatment dose; those based on calculated rad/organ did. Phase I clinical trials using treatment doses based on patient size where there are likely to be variations in patient antibody catabolism will result in confounding toxicities at apparently similar mCi dose levels. Use of pre-treatment scans for treatment dose planning are worth the additional effort by normalizing the normal tissue toxicity.

  6. Determination of the absorbed dose and the average LET of space radiation in dependence on shielding conditions.

    PubMed

    Vana, N; Schoner, W; Noll, M; Fugger, M; Akatov, Y; Shurshakov, V

    1999-01-01

    The HTR method, developed for determination of absorbed dose and average LET of mixed radiation fields in space, was applied during several space missions on space station MIR, space shuttles and satellites. The method utilises the changes of peak height ratios in the glow curves in dependence on the linear energy transfer LET. Due to the small size of the dosemeters the evaluation of the variation of absorbed dose and average LET in dependence on the position of the dosemeters inside the space station is possible. The dose and LET distribution was determined during the experiment ADLET where dosemeters were exposed in two positions with different shielding conditions and during two following experiments (MIR-95, MIR-96) using six positions inside the space station. The results were compared with the shielding conditions of the positions. Calculations of the absorbed dose were carried out for comparison. Results have shown that the average LET increases with increasing absorbing thickness while the absorbed dose decreases.

  7. Calculation of absorbed dose and biological effectiveness from photonuclear reactions in a bremsstrahlung beam of end point 50 MeV.

    PubMed

    Gudowska, I; Brahme, A; Andreo, P; Gudowski, W; Kierkegaard, J

    1999-09-01

    The absorbed dose due to photonuclear reactions in soft tissue, lung, breast, adipose tissue and cortical bone has been evaluated for a scanned bremsstrahlung beam of end point 50 MeV from a racetrack accelerator. The Monte Carlo code MCNP4B was used to determine the photon source spectrum from the bremsstrahlung target and to simulate the transport of photons through the treatment head and the patient. Photonuclear particle production in tissue was calculated numerically using the energy distributions of photons derived from the Monte Carlo simulations. The transport of photoneutrons in the patient and the photoneutron absorbed dose to tissue were determined using MCNP4B; the absorbed dose due to charged photonuclear particles was calculated numerically assuming total energy absorption in tissue voxels of 1 cm3. The photonuclear absorbed dose to soft tissue, lung, breast and adipose tissue is about (0.11-0.12)+/-0.05% of the maximum photon dose at a depth of 5.5 cm. The absorbed dose to cortical bone is about 45% larger than that to soft tissue. If the contributions from all photoparticles (n, p, 3He and 4He particles and recoils of the residual nuclei) produced in the soft tissue and the accelerator, and from positron radiation and gammas due to induced radioactivity and excited states of the nuclei, are taken into account the total photonuclear absorbed dose delivered to soft tissue is about 0.15+/-0.08% of the maximum photon dose. It has been estimated that the RBE of the photon beam of 50 MV acceleration potential is approximately 2% higher than that of conventional 60Co radiation.

  8. Dose reconstruction for real-time patient-specific dose estimation in CT

    SciTech Connect

    De Man, Bruno Yin, Zhye; Wu, Mingye; FitzGerald, Paul; Kalra, Mannudeep

    2015-05-15

    Purpose: Many recent computed tomography (CT) dose reduction approaches belong to one of three categories: statistical reconstruction algorithms, efficient x-ray detectors, and optimized CT acquisition schemes with precise control over the x-ray distribution. The latter category could greatly benefit from fast and accurate methods for dose estimation, which would enable real-time patient-specific protocol optimization. Methods: The authors present a new method for volumetrically reconstructing absorbed dose on a per-voxel basis, directly from the actual CT images. The authors’ specific implementation combines a distance-driven pencil-beam approach to model the first-order x-ray interactions with a set of Gaussian convolution kernels to model the higher-order x-ray interactions. The authors performed a number of 3D simulation experiments comparing the proposed method to a Monte Carlo based ground truth. Results: The authors’ results indicate that the proposed approach offers a good trade-off between accuracy and computational efficiency. The images show a good qualitative correspondence to Monte Carlo estimates. Preliminary quantitative results show errors below 10%, except in bone regions, where the authors see a bigger model mismatch. The computational complexity is similar to that of a low-resolution filtered-backprojection algorithm. Conclusions: The authors present a method for analytic dose reconstruction in CT, similar to the techniques used in radiation therapy planning with megavoltage energies. Future work will include refinements of the proposed method to improve the accuracy as well as a more extensive validation study. The proposed method is not intended to replace methods that track individual x-ray photons, but the authors expect that it may prove useful in applications where real-time patient-specific dose estimation is required.

  9. Calculation of fluence and absorbed dose in head tissues due to different photon energies.

    PubMed

    Azorín, C; Vega-Carrillo, H R; Rivera, T; Azorín, J

    2014-01-01

    Calculations of fluence and absorbed dose in head tissues due to different photon energies were carried out using the MCNPX code, to simulate two models of a patient's head: one spherical and another more realistic ellipsoidal. Both head models had concentric shells to describe the scalp skin, the cranium and the brain. The tumor was located at the center of the head and it was a 1 cm-radius sphere. The MCNPX code was run for different energies. Results showed that the fluence decreases as the photons pass through the different head tissues. It can be observed that, although the fluence into the tumor is different for both head models, absorbed dose is the same.

  10. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator

    NASA Astrophysics Data System (ADS)

    Puchalska, Monika; Sihver, Lembit

    2015-06-01

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  11. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator.

    PubMed

    Puchalska, Monika; Sihver, Lembit

    2015-06-21

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  12. On the suitability of ultrathin detectors for absorbed dose assessment in the presence of high-density heterogeneities

    SciTech Connect

    Bueno, M. Duch, M. A.; Carrasco, P.; Jornet, N.; Muñoz-Montplet, C.

    2014-08-15

    Purpose: The aim of this study was to evaluate the suitability of several detectors for the determination of absorbed dose in bone. Methods: Three types of ultrathin LiF-based thermoluminescent dosimeters (TLDs)—two LiF:Mg,Cu,P-based (MCP-Ns and TLD-2000F) and a{sup 7}Li-enriched LiF:Mg,Ti-based (MTS-7s)—as well as EBT2 Gafchromic films were used to measure percentage depth-dose distributions (PDDs) in a water-equivalent phantom with a bone-equivalent heterogeneity for 6 and 18 MV and a set of field sizes ranging from 5×5 cm{sup 2} to 20×20 cm{sup 2}. MCP-Ns, TLD-2000F, MTS-7s, and EBT2 have active layers of 50, 20, 50, and 30 μm, respectively. Monte Carlo (MC) dose calculations (PENELOPE code) were used as the reference and helped to understand the experimental results and to evaluate the potential perturbation of the fluence in bone caused by the presence of the detectors. The energy dependence and linearity of the TLDs’ response was evaluated. Results: TLDs exhibited flat energy responses (within 2.5%) and linearity with dose (within 1.1%) within the range of interest for the selected beams. The results revealed that all considered detectors perturb the electron fluence with respect to the energy inside the bone-equivalent material. MCP-Ns and MTS-7s underestimated the absorbed dose in bone by 4%–5%. EBT2 exhibited comparable accuracy to MTS-7s and MCP-Ns. TLD-2000F was able to determine the dose within 2% accuracy. No dependence on the beam energy or field size was observed. The MC calculations showed that a50 μm thick detector can provide reliable dose estimations in bone regardless of whether it is made of LiF, water or EBT’s active layer material. Conclusions: TLD-2000F was found to be suitable for providing reliable absorbed dose measurements in the presence of bone for high-energy x-ray beams.

  13. [Development of the 60Co gamma-ray standard field for therapy-level dosimeter calibration in terms of absorbed dose to water (N(D,w))].

    PubMed

    Fukumura, Akifumi; Mizuno, Hideyuki; Fukahori, Mai; Sakata, Suoh

    2012-01-01

    A primary standard for the absorbed dose rate to water in a 60Co gamma-ray field was established at National Metrology Institute of Japan (NMIJ) in fiscal year 2011. Then, a 60Co gamma-ray standard field for therapy-level dosimeter calibration in terms of absorbed dose to water was developed at National Institute of Radiological Sciences (NIRS) as a secondary standard dosimetry laboratory (SSDL). The results of an IAEA/WHO TLD SSDL audit demonstrated that there was good agreement between NIRS stated absorbed dose to water and IAEA measurements. The IAEA guide based on the ISO standard was used to estimate the relative expanded uncertainty of the calibration factor for a therapy-level Farmer type ionization chamber in terms of absorbed dose to water (N(D,w)) with the new field. The uncertainty of N(D,w) was estimated to be 1.1% (k = 2), which corresponds to approximately one third of the value determined in the existing air kerma field. The dissemination of traceability of the calibration factor determined in the new field is expected to diminish the uncertainty of dose delivered to patients significantly.

  14. Assessment of the Absorbed Dose in the Kidney of Nuclear Nephrology Paediatric Patients using ICRP Biokinetic Data and Monte Carlo Simulations with Mass-Scaled Paediatric Voxel Phantoms.

    PubMed

    Teles, P; Mendes, M; Zankl, M; de Sousa, V; Santos, A I; Vaz, P

    2016-04-21

    The aim of this work is to use Monte Carlo simulations and VOXEL phantoms to estimate the absorbed dose in paediatric patients (aged from 2 weeks to 16 y), with normal renal function, to whom technetium-99m-dimercaptosuccinic acid ((99m)Tc-DMSA) was administered, for diagnostic renal scintigraphy purposes; and compare them with values obtained using the International Commission on Radiological Protection (ICRP) methodology. In the ICRP methodology, the cumulated absorbed dose in the kidneys is estimated by multiplying the administered activity with the corresponding given dose coefficients. The other methods were based on Monte Carlo simulations performed on two paediatric voxel phantoms ( ITALIC! CHILDand ITALIC! BABY), and another three phantoms, which were modified to suit the mass of the patients' kidneys, and other anatomical factors. Different ITALIC! S-values were estimated using this methodology, which together with solving the ICRP biokinetic model to determine the cumulated activities, allowed for the estimation of absorbed doses different from those obtained with the ICRP method, together with new dose coefficients. The obtained values were then compared. The deviations suggest that the ITALIC! S-values are strongly dependent on the patient's total body weight, which could be in contrast with the ICRP data, which is provided by age, regardless of other anatomical parameters.

  15. Absorbed doses and energy imparted from radiographic examination of velopharyngeal function during speech

    SciTech Connect

    Isberg, A.; Julin, P.; Kraepelien, T.; Henrikson, C.O. )

    1989-04-01

    Absorbed doses of radiation were measured by thermoluminescent dosimeters (TLDs) using a skull phantom during simulated cinefluorographic and videofluorographic examination of velopharyngeal function in frontal and lateral projections. Dosages to the thyroid gland, the parotid gland, the pituitary gland, and ocular lens were measured. Radiation dosage was found to be approximately 10 times less for videofluoroscopy when compared with that of cinefluoroscopy. In addition, precautionary measures were found to reduce further the exposure of radiation-sensitive tissues. Head fixation and shielding resulted in dose reduction for both video- and cinefluoroscopy. Pulsing exposure for cinefluoroscopy also reduced the dosage.

  16. Absorbed Dose Calculations Using Mesh-based Human Phantoms And Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Kramer, Richard

    2011-08-01

    Health risks attributable to the exposure to ionizing radiation are considered to be a function of the absorbed or equivalent dose to radiosensitive organs and tissues. However, as human tissue cannot express itself in terms of equivalent dose, exposure models have to be used to determine the distribution of equivalent dose throughout the human body. An exposure model, be it physical or computational, consists of a representation of the human body, called phantom, plus a method for transporting ionizing radiation through the phantom and measuring or calculating the equivalent dose to organ and tissues of interest. The FASH2 (Female Adult meSH) and the MASH2 (Male Adult meSH) computational phantoms have been developed at the University of Pernambuco in Recife/Brazil based on polygon mesh surfaces using open source software tools and anatomical atlases. Representing standing adults, FASH2 and MASH2 have organ and tissue masses, body height and body mass adjusted to the anatomical data published by the International Commission on Radiological Protection for the reference male and female adult. For the purposes of absorbed dose calculations the phantoms have been coupled to the EGSnrc Monte Carlo code, which can transport photons, electrons and positrons through arbitrary media. This paper reviews the development of the FASH2 and the MASH2 phantoms and presents dosimetric applications for X-ray diagnosis and for prostate brachytherapy.

  17. [Absorbed dose conversion factors obtained from X-ray spectra measured at water phantom surface].

    PubMed

    Aoki, Kiyoshi; Koyama, Masaki

    2005-03-20

    The absorbed dose conversion factor for X-rays at the water phantom surface has been obtained from the measured spectra. These measurements have been made at tube voltages of 60 kV to 120 kV and field sizes ranging from 5 x 5 cm(2) to 30 x 30 cm(2) with and without additional 2 mm aluminium filtration. A small silicon diode detector with little angular dependence was used for this measurement. The absorbed dose conversion factor obtained was 0.03-0.43% smaller than that obtained from the primary X-ray spectrum. The difference was large for high-voltage and heavily filtered X-rays. As field size increases, the conversion factor decreases, but the decrease is slight when field size exceeds 20 x 20 cm(2). The absorbed dose conversion factor obtained from the primary or surface X-ray spectrum is 0.4-1.8% larger than that obtained from the effective energy of primary X-rays. The difference is large in high-voltage X-rays and decreases slightly with increases in field size.

  18. Influence of lead apron shielding on absorbed doses from cone-beam computed tomography.

    PubMed

    Rottke, Dennis; Andersson, Jonas; Ejima, Ken-Ichiro; Sawada, Kunihiko; Schulze, Dirk

    2016-09-24

    The aim of the present work was to investigate absorbed and to calculate effective doses (EDs) in cone-beam computed tomography (CBCT). The study was conducted using examination protocols with and without lead apron shielding. A full-body male RANDO(®) phantom was loaded with 110 GR200A thermoluminescence dosemeter chips at 55 different sites and set up in two different CBCT systems (CS 9500(®), ProMax(®) 3D). Two different protocols were performed: the phantom was set up (1) with and (2) without a lead apron. No statistically significant differences in organ and absorbed doses from regions outside the primary beam could be found when comparing results from exposures with and without lead apron shielding. Consequently, calculating the ED showed no significant differences between the examination protocols with and without lead apron shielding. For the ProMax(®) 3D with shielding, the ED was 149 µSv, and for the examination protocol without shielding 148 µSv (SD = 0.31 µSv). For the CS 9500(®), the ED was 88 and 86 µSv (SD = 0.95 µSv), respectively, with and without lead apron shielding. The results revealed no statistically significant differences in the absorbed doses between examination with and without lead apron shielding, especially in organs outside the primary beam.

  19. Mycosis Fungoides electron beam absorbed dose distribution using Fricke xylenol gel dosimetry

    NASA Astrophysics Data System (ADS)

    da Silveira, Michely C.; Sampaio, Francisco G. A.; Petchevist, Paulo C. D.; de Oliveira, André L.; Almeida, Adelaide de

    2011-12-01

    Radiotherapy uses ionizing radiation to destroy tumor cells. The absorbed dose control in the target volume is realized through radiation sensors, such as Fricke dosimeters and radiochromic film, which permit to realize bi-dimensional evaluations at once and because of that, they will be used in this study as well. Among the several types of cancer suitable for ionizing radiation treatment, the Mycosis Fungoides, a lymphoma that spreads on the skin surface and depth, requires for its treatment total body irradiation by high-energy electrons. In this work the Fricke xylenol gel (FXG) was used in order to obtain information about the absorbed dose distribution induced by the electron interactions with the irradiated tissues and to control this type of treatment. FXG can be considered as an alternative dosimeter, since up to now only films have been used. FXG sample cuvettes, simulating two selected tomos (cranium and abdomen) of the Rando anthropomorphic phantom, were positioned along with radiochromic films for comparison. The phantom was subjected to Stanford total body irradiation using 6 MeV electrons. Tomographic images were acquired for both dosimeters and evaluated through horizontal and vertical profiles along the tomographic centers. These profiles were obtained through a Matlab routine developed for this purpose. From the obtained results, one could infer that, for a superficial and internal patient irradiation, the FXG dosimeter showed an absorbed dose distribution similar to the one of the film. These results can validate the FXG dosimeter as an alternative dosimeter for the Mycosis Fungoides treatment planning.

  20. Development of modern approach to absorbed dose assessment in radionuclide therapy, based on Monte Carlo method simulation of patient scintigraphy

    NASA Astrophysics Data System (ADS)

    Lysak, Y. V.; Klimanov, V. A.; Narkevich, B. Ya

    2017-01-01

    One of the most difficult problems of modern radionuclide therapy (RNT) is control of the absorbed dose in pathological volume. This research presents new approach based on estimation of radiopharmaceutical (RP) accumulated activity value in tumor volume, based on planar scintigraphic images of the patient and calculated radiation transport using Monte Carlo method, including absorption and scattering in biological tissues of the patient, and elements of gamma camera itself. In our research, to obtain the data, we performed modeling scintigraphy of the vial with administered to the patient activity of RP in gamma camera, the vial was placed at the certain distance from the collimator, and the similar study was performed in identical geometry, with the same values of activity of radiopharmaceuticals in the pathological target in the body of the patient. For correct calculation results, adapted Fisher-Snyder human phantom was simulated in MCNP program. In the context of our technique, calculations were performed for different sizes of pathological targets and various tumors deeps inside patient’s body, using radiopharmaceuticals based on a mixed β-γ-radiating (131I, 177Lu), and clear β- emitting (89Sr, 90Y) therapeutic radionuclides. Presented method can be used for adequate implementing in clinical practice estimation of absorbed doses in the regions of interest on the basis of planar scintigraphy of the patient with sufficient accuracy.

  1. A geochemical assessment of terrestrial gamma-ray absorbed dose rates.

    PubMed

    Wollenberg, H A; Smith, A R

    1990-02-01

    A survey of the geochemical literature and unpublished data has resulted in the classification of the concentrations of the naturally occurring radioelements U, Th, and K by their associated rock types. A data base of over 2500 entries has been compiled, permitting calculation of terrestrial gamma-ray absorbed dose rates. The general lithology of terrains may be distinguished by their radioelement ratios, relative abundances, and total gamma radioactivities. The gamma-ray absorbed dose rates in air above igneous rocks generally vary with their silica contents, and with the exception of shale, sedimentary rocks have lower K:U and K:Th ratios than most igneous rocks. The appreciable difference between the overall mean terrestrial gamma-ray dose rate for rock of the continental surface (approximately 7 X 10(-8) Gy h-1) and the mean dose rate from field measurements over soil (approximately 5 X 10(-8) Gy h-1) is explained by the substantial differences between radioelement concentrations of soil and rock, differences that may vary markedly with rock type.

  2. High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin's Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes

    SciTech Connect

    Rajendran, Joseph G.; Fisher, Darrell R.; Gopal, A K.; Durack, L. D.; Press, O. W.; Eary, Janet F.

    2004-06-01

    Radioimmunotherapy (RIT) using 131I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on radiation absorbed close to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific absorbed dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 131I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar -camera images and whole-body Nal probe counts were obtained to estimate 131I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean radiation absorbed doses (in mGy/MBq) for our data using the MIRD model were lungs= 1.67; liver= 1.03; kidneys= 1.08; spleen= 2.67; and whole body= 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs= 1.30; liver= 0.92; kidneys= 0.76; spleen= 1.40; and whole body= 0.22. We determined the following correlation coefficients between the 2 methods for the various organs; lungs, 0.49; (P= 0.0001); liver, 0.64 (P= 0.004); kidneys, 0.45 (P= 0.0001), for the residence times. For therapy, patients received mean 131I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes--a statistically significant difference (P= 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated radiation dose to the dose-limiting normal organ. This work provides a simplified method for calculating patient-specific radiation

  3. Detailed Distribution Map of Absorbed Dose Rate in Air in Tokatsu Area of Chiba Prefecture, Japan, Constructed by Car-Borne Survey 4 Years after the Fukushima Daiichi Nuclear Power Plant Accident.

    PubMed

    Inoue, Kazumasa; Arai, Moeko; Fujisawa, Makoto; Saito, Kyouko; Fukushi, Masahiro

    2017-01-01

    A car-borne survey was carried out in the northwestern, or Tokatsu, area of Chiba Prefecture, Japan, to make a detailed distribution map of absorbed dose rate in air four years after the Fukushima Daiichi Nuclear Power Plant accident. This area was chosen because it was the most heavily radionuclide contaminated part of Chiba Prefecture and it neighbors metropolitan Tokyo. Measurements were performed using a 3-in × 3-in NaI(Tl) scintillation spectrometer in June 2015. The survey route covered the whole Tokatsu area which includes six cities. A heterogeneous distribution of absorbed dose rate in air was observed on the dose distribution map. Especially, higher absorbed dose rates in air exceeding 80 nGy h-1 were observed along national roads constructed using high porosity asphalt, whereas lower absorbed dose rates in air were observed along local roads constructed using low porosity asphalt. The difference between these asphalt types resulted in a heterogeneous dose distribution in the Tokatsu area. The mean of the contribution ratio of artificial radionuclides to absorbed dose rate in air measured 4 years after the accident was 29% (9-50%) in the Tokatsu area. The maximum absorbed dose rate in air, 201 nGy h-1 was observed at Kashiwa City. Radiocesium was deposited in the upper 1 cm surface layer of the high porosity asphalt which was collected in Kashiwa City and the environmental half-life of the absorbed dose rate in air was estimated to be 1.7 years.

  4. Differential absorbed dose distributions in lineal energy for neutrons and gamma rays at the mono-energetic neutron calibration facility.

    PubMed

    Takada, M; Baba, M; Yamaguchi, H; Fujitaka, K

    2005-01-01

    Absorbed dose distributions in lineal energy for neutrons and gamma rays of mono-energetic neutron sources from 140 keV to 15 MeV were measured in the Fast Neutron Laboratory at Tohoku University. By using both a tissue-equivalent plastic walled counter and a graphite-walled low-pressure proportional counter, absorbed dose distributions in lineal energy for neutrons were obtained separately from those for gamma rays. This method needs no knowledge of energy spectra and dose distributions for gamma rays. The gamma-ray contribution in this neutron calibration field >1 MeV neutron was <3%, while for <550 keV it was >40%. The measured neutron absolute absorbed doses per unit neutron fluence agreed with the LA150 evaluated kerma factors. By using this method, absorbed dose distributions in lineal energy for neutrons and gamma rays in an unknown neutron field can be obtained separately.

  5. Distribution of absorbed doses in the materials irradiated by ''RHODOTRON'' electron accelerator: Experiment and Monte Carlo simulations

    SciTech Connect

    Oleg E. Krivosheev et al.

    2001-07-02

    This paper describes the experimental setup and presents studies of absorbed doses in different metals and dielectrics along with corresponding Monte Carlo energy deposition simulations. Experiments were conducted using a 5 MeV electron accelerator. We used several Monte Carlo code systems, namely MARS, MCNP, and GEANT to simulate the absorbed doses under the same conditions as in experiment. We compare calculated and measured high and low absorbed doses (from few kGy to hundreds kGy) and discuss the applicability of these computer codes for applied accelerator dosimetry.

  6. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    SciTech Connect

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-21

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely {sup 40}K, {sup 232}Th and {sup 238}U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

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

    PubMed

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

    2016-08-20

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

  8. Estimated radiation dose to the newborn in FDG-PET studies

    SciTech Connect

    Ruotsalainen, U.; Suhonen-Polvi, H.; Eronen, E.; Kinnala, A.

    1996-02-01

    The aim of this study was to estimate the radiation dose due to intravenous injection of 2-[{sup 18}F]fluoro-2-deoxy-D-glucose (FDG) for infants studied with PET. The radioactivity concentration in the brain and bladder content was measured with PET to determine the cumulated activity in these organs in 21 infant FDG studies. The individual organ masses were estimated according to the whole-body and brain masses, and they were used to calculate the absorbed dose per unit cumulated activity (S values). For organs other than brain and bladder, the cumulated activity was defined from adult studies. For each individual patient, the absorbed dose to the brain, bladder wall and selected organs were calculated. An estimation of the effective dose was determined. Whole-body distribution of FDG in the infants differed from adults: a greater proportion of the injected activity accumulated into the brain (9% versus 7%) and less was excreted to urine (7% versus 20% respectively). The measured cumulated activity in the brain was 0.25 MBq {center_dot} h/MBq and in the bladder content 0.04 MBq {center_dot}h/MBq with a large individual variation in latter. The calculated absorbed dose was 0.24 mGy/MBq to the brain and 1.03 mGy/MBq to the bladder wall. The estimated effective dose was 0.43 mSv/MBq. The dose to the bladder wall was lower in infants as compared to adults with ordinary amounts of injected activity. The greater amount of activity remaining in the body may increase the dose to other organs. The effective dose was lower compared to adults and conventional nuclear medicine studies of infants. PET can be a valuable tool in pediatric nuclear medicine because of good resolution images, sensitive radiation measurement and a variety of tracers labeled with short-lived isotopes. 27 refs., 4 figs., 2 tabs.

  9. Absorbed dose determination in kilovoltage X-ray synchrotron radiation using alanine dosimeters.

    PubMed

    Butler, D J; Lye, J E; Wright, T E; Crossley, D; Sharpe, P H G; Stevenson, A W; Livingstone, J; Crosbie, J C

    2016-12-01

    Alanine dosimeters from the National Physical Laboratory (NPL) in the UK were irradiated using kilovoltage synchrotron radiation at the imaging and medical beam line (IMBL) at the Australian Synchrotron. A 20 × 20 mm(2) area was irradiated by scanning the phantom containing the alanine through the 1 mm × 20 mm beam at a constant velocity. The polychromatic beam had an average energy of 95 keV and nominal absorbed dose to water rate of 250 Gy/s. The absorbed dose to water in the solid water phantom was first determined using a PTW Model 31014 PinPoint ionization chamber traceable to a graphite calorimeter. The alanine was read out at NPL using correction factors determined for (60)Co, traceable to NPL standards, and a published energy correction was applied to correct for the effect of the synchrotron beam quality. The ratio of the doses determined by alanine at NPL and those determined at the synchrotron was 0.975 (standard uncertainty 0.042) when alanine energy correction factors published by Waldeland et al. (Waldeland E, Hole E O, Sagstuen E and Malinen E, Med. Phys. 2010, 37, 3569) were used, and 0.996 (standard uncertainty 0.031) when factors by Anton et al. (Anton M, Büermann L., Phys Med Biol. 2015 60 6113-29) were used. The results provide additional verification of the IMBL dosimetry.

  10. Technique-dependent decrease in thyroid absorbed dose for dental radiography.

    PubMed

    Wood, R E; Bristow, R G; Clark, G M; Nussbaum, C; Taylor, K W

    1989-06-01

    A LiF thermoluminescent dosimetry (TLD) system, calibrated in the tissue of interest with the beam used for experimentation, was employed to investigate dosages (muGy) to the thyroid region of an anthropomorphic phantom resultant from two dental complete-mouth radiographic procedures. Both techniques were compared in terms of dosages associated with combinations of lead apron and thyroid collar shielding while using a 70-kVp or 90-kVp x-ray beam for a 20-film complete-mouth series. Lead shielding significantly decreased the dose to the thyroid using both techniques (p less than 0.05). The use of the 90-kVp beam resulted in a significant reduction in the thyroid absorbed dose when using the bisecting angle technique (p less than 0.05) but caused a significant increase in the thyroid absorbed dose when the paralleling technique was used (p less than 0.05). The implementation of higher kilovoltage techniques in dental offices must therefore be dependent on the radiographic technique employed.

  11. Technique-dependent decrease in thyroid absorbed dose for dental radiography

    SciTech Connect

    Wood, R.E.; Bristow, R.G.; Clark, G.M.; Nussbaum, C.; Taylor, K.W.

    1989-06-01

    A LiF thermoluminescent dosimetry (TLD) system, calibrated in the tissue of interest with the beam used for experimentation, was employed to investigate dosages (muGy) to the thyroid region of an anthropomorphic phantom resultant from two dental complete-mouth radiographic procedures. Both techniques were compared in terms of dosages associated with combinations of lead apron and thyroid collar shielding while using a 70-kVp or 90-kVp x-ray beam for a 20-film complete-mouth series. Lead shielding significantly decreased the dose to the thyroid using both techniques (p less than 0.05). The use of the 90-kVp beam resulted in a significant reduction in the thyroid absorbed dose when using the bisecting angle technique (p less than 0.05) but caused a significant increase in the thyroid absorbed dose when the paralleling technique was used (p less than 0.05). The implementation of higher kilovoltage techniques in dental offices must therefore be dependent on the radiographic technique employed.

  12. Contribution to Neutron Fluence and Neutron Absorbed Dose from Double Scattering Proton Therapy System Components

    PubMed Central

    Pérez-Andújar, A.; Newhauser, W. D.; DeLuca, P. M.

    2010-01-01

    Proton therapy offers low integral dose and good tumor comformality in many deep-seated tumors. However, secondary particles generated during proton therapy, such as neutrons, are a concern, especially for passive scattering systems. In this type of system, the proton beam interacts with several components of the treatment nozzle that lie along the delivery path and can produce secondary neutrons. Neutron production along the beam's central axis in a double scattering passive system was examined using Monte Carlo simulations. Neutron fluence and energy distribution were determined downstream of the nozzle's major components at different radial distances from the central axis. In addition, the neutron absorbed dose per primary proton around the nozzle was investigated. Neutron fluence was highest immediately downstream of the range modulator wheel (RMW) but decreased as distance from the RMW increased. The nozzle's final collimator and snout also contributed to the production of high-energy neutrons. In fact, for the smallest treatment volume simulated, the neutron absorbed dose per proton at isocenter increased by a factor of 20 due to the snout presence when compared with a nozzle without a snout. The presented results can be used to design more effective local shielding components inside the treatment nozzle as well as to better understand the treatment room shielding requirements. PMID:20871789

  13. [National primary standard of absorbed dose rate to water using a graphite calorimeter].

    PubMed

    Morishita, Yuichiro

    2013-01-01

    The calibration service in terms of absorbed dose to water started from 2011 after establishment of the national primary standard using a graphite calorimeter at the national metrology institute of Japan (NMIJ) and JCSS accreditation of the association for nuclear technology in medicine (ANTM). Accordingly, a new dosimetry protocol was introduced as JSMP12, in which details of the national standard were also described. This report presents a short review of the standard, a key comparison result, and a comparison result of calibration coefficients by JSMP01 and JSMP12.

  14. Estimating the Radiation Dose to the Fetus in Prophylactic Internal Iliac Artery Balloon Occlusion: Three Cases

    PubMed Central

    Kai, Kentaro; Hamada, Tomohiro; Yuge, Akitoshi; Kiyosue, Hiro; Nishida, Yoshihiro; Nasu, Kaei; Narahara, Hisashi

    2015-01-01

    Background. Although radiation exposure is of great concern to expecting patients, little information is available on the fetal radiation dose associated with prophylactic internal iliac artery balloon occlusion (IIABO). Here we estimated the fetal radiation dose associated with prophylactic IIABO in Caesarean section (CS). Cases. We report our experience with the IIABO procedure in three consecutive patients with suspected placenta previa/accreta. Fetal radiation dose measurements were conducted prior to each CS by using an anthropomorphic phantom. Based on the simulated value, we calculated the fetal radiation dose as the absorbed dose. We found that the fetal radiation doses ranged from 12.88 to 31.6 mGy. The fetal radiation dose during the prophylactic IIABOs did not exceed 50 mGy. Conclusion. The IIABO procedure could result in a very small increase in the risk of harmful effects to the fetus. PMID:26180648

  15. Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film.

    PubMed

    Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

    2016-01-01

    Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were -32.336 and -33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.

  16. Radiation dose estimate in small animal SPECT and PET.

    PubMed

    Funk, Tobias; Sun, Mingshan; Hasegawa, Bruce H

    2004-09-01

    Calculations of radiation dose are important in assessing the medical and biological implications of ionizing radiation in medical imaging techniques such as SPECT and PET. In contrast, radiation dose estimates of SPECT and PET imaging of small animals are not very well established. For that reason we have estimated the whole-body radiation dose to mice and rats for isotopes such as 18F, 99mTc, 201Tl, (111)In, 123I, and 125I that are used commonly for small animal imaging. We have approximated mouse and rat bodies with uniform soft tissue equivalent ellipsoids. The mouse and rat sized ellipsoids had a mass of 30 g and 300 g, respectively, and a ratio of the principal axes of 1:1:4 and 0.7:1:4. The absorbed fractions for various photon energies have been calculated using the Monte Carlo software package MCNP. Using these values, we then calculated MIRD S-values for two geometries that model the distribution of activity in the animal body: (a) a central point source and (b) a homogeneously distributed source, and compared these values against S-value calculations for small ellipsoids tabulated in MIRD Pamphlet 8 to validate our results. Finally we calculated the radiation dose taking into account the biological half-life of the radiopharmaceuticals and the amount of activity administered. Our calculations produced S-values between 1.06 x 10(-13) Gy/Bq s and 2.77 x 10(-13) Gy/Bq s for SPECT agents, and 15.0 x 10(-13) Gy/Bq s for the PET agent 18F, assuming mouse sized ellipsoids with uniform source distribution. The S-values for a central point source in an ellipsoid are about 10% higher than the values obtained for the uniform source distribution. Furthermore, the S-values for mouse sized ellipsoids are approximately 10 times higher than for the rat sized ellipsoids reflecting the difference in mass. We reviewed published data to obtain administered radioactivity and residence times for small animal imaging. From these values and our computed S-values we estimated

  17. Radiation-induced biomarkers for the detection and assessment of absorbed radiation doses

    PubMed Central

    Rana, Sudha; Kumar, Raj; Sultana, Sarwat; Sharma, Rakesh Kumar

    2010-01-01

    Radiation incident involving living organisms is an uncommon but a very serious situation. The first step in medical management including triage is high-throughput assessment of the radiation dose received. Radiation exposure levels can be assessed from viability of cells, cellular organelles such as chromosome and different intermediate metabolites. Oxidative damages by ionizing radiation result in carcinogenesis, lowering of the immune response and, ultimately, damage to the hematopoietic system, gastrointestinal system and central nervous system. Biodosimetry is based on the measurement of the radiation-induced changes, which can correlate them with the absorbed dose. Radiation biomarkers such as chromosome aberration are most widely used. Serum enzymes such as serum amylase and diamine oxidase are the most promising biodosimeters. The level of gene expression and protein are also good biomarkers of radiation. PMID:21829314

  18. Comparison of Accuracy in Calculation of Absorbed Dose to Patients Following Bone Scan with 99mTc-Marked Diphosphonates by Two Different Background Correction Methods

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Damoori, Mehri; Tavakoli, Mohammad Bagher; Moslehi, Masoud

    2016-01-01

    To improve the accuracy of the activity quantification and the image quality in scintigraphy, scatter correction is a vital procedure. The aim of this study is to compare the accuracy in calculation of absorbed dose to patients following bone scan with 99mTc-marked diphosphonates (99mTc-MDP) by two different methods of background correction in conjugate view method. This study involved 22 patients referring to the Nuclear Medicine Center of Shahid Chamran Hospital, Isfahan, Iran. After the injection of 99mTc-MDP, whole-body images from patients were acquired at 10, 60, 90, and 180 min. Organ activities were calculated using the conjugate view method by Buijs and conventional background correction. Finally, the absorbed dose was calculated using the Medical Internal Radiation Dosimetry (MIRD) technique. The results of this study showed that the absorbed dose per unit of injected activity (rad/mCi) ± standard deviation for pelvis bone, bladder, and kidneys by Buijs method was 0.19 ± 0.05, 0.08 ± 0.01, and 0.03 ± 0.01 and by conventional method was 0.13 ± 0.04, 0.08 ± 0.01, and 0.024 ± 0.01, respectively. This showed that Buijs background correction method had a high accuracy compared to conventional method for the estimated absorbed dose of bone and kidneys whereas, for the bladder, its accuracy was low. PMID:27014610

  19. Human absorbed dose calculations for iodine-131 and iodine-123 labeled meta-iodobenzyl-guanidine (mIBG): a potential myocardial and adrenal medulla imaging agent

    SciTech Connect

    Swanson, D.P.; Carey, J.E.; Brown, L.E.; Kline, R.C.; Wieland, D.M.; Thrall, J.H.; Beierwaltes, W.H.

    1981-06-01

    Tissue distribution studies with radiolabeled meta-iodobenzyl-guanidine (mIBG), an analog of the adrenergic neuronal blocking agent-guanethidine, suggest that this radiotracer may be useful for both myocardial imaging (labeled with I-123) and adrenal medulla imaging (labeled with I-131). Total body elimination was determined by whole body counting (well-type ionization chamber) of rats administered /sup 131/I-mIBG and time-activity tissue distribution data was obtained in dogs using /sup 125/I-mIBG. Using the MIRD formalism, researchers have estimated the human absorbed dose from /sup 131/I-mIBG, radionuclidically pure /sup 123/I-mIBG, and /sup 1/''/sup 3/I-mIBG contaminated with 4.8% /sup 125/I-mIBG (based on /sup 123/I radionuclidic purity specification of 1.4% I-125 at calibration). The largest absorbed dose from /sup 131/I-mIBG was delivered to the adrenals. For pure /sup 123/I-mIBG the largest absorbed dose was delivered to the thyroid (unblocked). The /sup 125/I contamination increased the absorbed dose to the adrenal medulla by a factor of 3.5.

  20. Development and characterization of an interferometer for calorimeter-based absorbed dose to water measurements in a medical linear accelerator

    NASA Astrophysics Data System (ADS)

    Flores-Martinez, Everardo; Malin, Martha J.; DeWerd, Larry A.

    2016-11-01

    The quantity of relevance for external beam radiotherapy is absorbed dose to water (ADW). An interferometer was built, characterized, and tested to measure ADW within the dose range of interest for external beam radiotherapy using the temperature dependence of the refractive index of water. The interferometer was used to measure radiation-induced phase shifts of a laser beam passing through a (10 × 10 × 10) cm3 water-filled glass phantom, irradiated with a 6 MV photon beam from a medical linear accelerator. The field size was (7 × 7) cm2 and the dose was measured at a depth of 5 cm in the water phantom. The intensity of the interference pattern was measured with a photodiode and was used to calculate the time-dependent phase shift curve. The system was thermally insulated to achieve temperature drifts of less than 1.5 mK/min. Data were acquired 60 s before and after the irradiation. The radiation-induced phase shifts were calculated by taking the difference in the pre- and post-irradiation drifts extrapolated to the midpoint of the irradiation. For 200, 300, and 400 monitor units, the measured doses were 1.6 ± 0.3, 2.6 ± 0.3, and 3.1 ± 0.3 Gy, respectively. Measurements agreed within the uncertainty with dose calculations performed with a treatment planning system. The estimated type-A, k = 1 uncertainty in the measured doses was 0.3 Gy which is an order of magnitude lower than previously published interferometer-based ADW measurements.

  1. Development and characterization of an interferometer for calorimeter-based absorbed dose to water measurements in a medical linear accelerator.

    PubMed

    Flores-Martinez, Everardo; Malin, Martha J; DeWerd, Larry A

    2016-11-01

    The quantity of relevance for external beam radiotherapy is absorbed dose to water (ADW). An interferometer was built, characterized, and tested to measure ADW within the dose range of interest for external beam radiotherapy using the temperature dependence of the refractive index of water. The interferometer was used to measure radiation-induced phase shifts of a laser beam passing through a (10 × 10 × 10) cm(3) water-filled glass phantom, irradiated with a 6 MV photon beam from a medical linear accelerator. The field size was (7 × 7) cm(2) and the dose was measured at a depth of 5 cm in the water phantom. The intensity of the interference pattern was measured with a photodiode and was used to calculate the time-dependent phase shift curve. The system was thermally insulated to achieve temperature drifts of less than 1.5 mK/min. Data were acquired 60 s before and after the irradiation. The radiation-induced phase shifts were calculated by taking the difference in the pre- and post-irradiation drifts extrapolated to the midpoint of the irradiation. For 200, 300, and 400 monitor units, the measured doses were 1.6 ± 0.3, 2.6 ± 0.3, and 3.1 ± 0.3 Gy, respectively. Measurements agreed within the uncertainty with dose calculations performed with a treatment planning system. The estimated type-A, k = 1 uncertainty in the measured doses was 0.3 Gy which is an order of magnitude lower than previously published interferometer-based ADW measurements.

  2. Estimating radiation effective doses from whole body computed tomography scans based on U.S. soldier patient height and weight

    PubMed Central

    2011-01-01

    Background The purpose of this study is to explore how a patient's height and weight can be used to predict the effective dose to a reference phantom with similar height and weight from a chest abdomen pelvis computed tomography scan when machine-based parameters are unknown. Since machine-based scanning parameters can be misplaced or lost, a predictive model will enable the medical professional to quantify a patient's cumulative radiation dose. Methods One hundred mathematical phantoms of varying heights and weights were defined within an x-ray Monte Carlo based software code in order to calculate organ absorbed doses and effective doses from a chest abdomen pelvis scan. Regression analysis was used to develop an effective dose predictive model. The regression model was experimentally verified using anthropomorphic phantoms and validated against a real patient population. Results Estimates of the effective doses as calculated by the predictive model were within 10% of the estimates of the effective doses using experimentally measured absorbed doses within the anthropomorphic phantoms. Comparisons of the patient population effective doses show that the predictive model is within 33% of current methods of estimating effective dose using machine-based parameters. Conclusions A patient's height and weight can be used to estimate the effective dose from a chest abdomen pelvis computed tomography scan. The presented predictive model can be used interchangeably with current effective dose estimating techniques that rely on computed tomography machine-based techniques. PMID:22004072

  3. Response functions for computing absorbed dose to skeletal tissues from photon irradiation.

    PubMed

    Eckerman, K F; Bolch, W E; Zankl, M; Petoussi-Henss, N

    2007-01-01

    The calculation of absorbed dose in skeletal tissues at radiogenic risk has been a difficult problem because the relevant structures cannot be represented in conventional geometric terms nor can they be visualised in the tomographic image data used to define the computational models of the human body. The active marrow, the tissue of concern in leukaemia induction, is present within the spongiosa regions of trabecular bone, whereas the osteoprogenitor cells at risk for bone cancer induction are considered to be within the soft tissues adjacent to the mineral surfaces. The International Commission on Radiological Protection (ICRP) recommends averaging the absorbed energy over the active marrow within the spongiosa and over the soft tissues within 10 microm of the mineral surface for leukaemia and bone cancer induction, respectively. In its forthcoming recommendation, it is expected that the latter guidance will be changed to include soft tissues within 50 microm of the mineral surfaces. To address the computational problems, the skeleton of the proposed ICRP reference computational phantom has been subdivided to identify those voxels associated with cortical shell, spongiosa and the medullary cavity of the long bones. It is further proposed that the Monte Carlo calculations with these phantoms compute the energy deposition in the skeletal target tissues as the product of the particle fluence in the skeletal subdivisions and applicable fluence-to-dose-response functions. This paper outlines the development of such response functions for photons.

  4. Secondary absorbed doses from light ion irradiation in anthropomorphic phantoms representing an adult male and a 10 year old child

    NASA Astrophysics Data System (ADS)

    Hultqvist, Martha; Gudowska, Irena

    2010-11-01

    Secondary organ absorbed doses were calculated by Monte Carlo simulations with the SHIELD-HIT07 code coupled with the mathematical anthropomorphic phantoms CHILD-HIT and ADAM-HIT. The simulated irradiations were performed with primary 1H, 4He, 7Li, 12C and 16O ion beams in the energy range 100-400 MeV/u which were directly impinging on the phantoms, i.e. approximating scanned beams, and with a simplified beamline for 12C irradiation. The evaluated absorbed doses to the out-of-field organs were in the range 10-6 to 10-1 mGy per target Gy and with standard deviations 0.5-20%. While the contribution to the organ absorbed doses from secondary neutrons dominated in the ion beams of low atomic number Z, the produced charged fragments and their subsequent charged secondaries of higher generations became increasingly important for the secondary dose delivery as Z of the primary ions increased. As compared to the simulated scanned 12C ion beam, the implementation of a simplified beamline for prostate irradiation with 12C ions resulted in an increase of 2-50 times in the organ absorbed doses depending on the distance from the target volume. Comparison of secondary organ absorbed doses delivered by 1H and 12C beams showed smaller differences when the RBE for local tumor control of the ions was considered and normalization to the RBE-weighted dose to the target was performed.

  5. Dose estimates of alternative plutonium pyrochemical processes.

    SciTech Connect

    Kornreich, D. E.; Jackson, J. W.; Boerigter, S. T.; Averill, W. A.; Fasel, J. H.

    2002-01-01

    We have coupled our dose calculation tool Pandemonium with a discrete-event, object-oriented, process-modeling system ProMosO to analyze a set of alternatives for plutonium purification operations. The results follow expected trends and indicate, from a dose perspective, that an experimental flowsheet may warrant further research to see if it can be scaled to industrial levels. Flowsheets that include fluoride processes resulted in the largest doses.

  6. Whole organ and islet of Langerhans dosimetry for calculation of absorbed doses resulting from imaging with radiolabeled exendin

    PubMed Central

    van der Kroon, Inge; Woliner-van der Weg, Wietske; Brom, Maarten; Joosten, Lieke; Frielink, Cathelijne; Konijnenberg, Mark W.; Visser, Eric P.; Gotthardt, Martin

    2017-01-01

    Radiolabeled exendin is used for non-invasive quantification of beta cells in the islets of Langerhans in vivo. High accumulation of radiolabeled exendin in the islets raised concerns about possible radiation-induced damage to these islets in man. In this work, islet absorbed doses resulting from exendin-imaging were calculated by combining whole organ dosimetry with small scale dosimetry for the islets. Our model contains the tissues with high accumulation of radiolabeled exendin: kidneys, pancreas and islets. As input for the model, data from a clinical study (radiolabeled exendin distribution in the human body) and from a preclinical study with Biobreeding Diabetes Prone (BBDP) rats (islet-to-exocrine uptake ratio, beta cell mass) were used. We simulated 111In-exendin and 68Ga-exendin absorbed doses in patients with differences in gender, islet size, beta cell mass and radiopharmaceutical uptake in the kidneys. In all simulated cases the islet absorbed dose was small, maximum 1.38 mGy for 68Ga and 66.0 mGy for 111In. The two sources mainly contributing to the islet absorbed dose are the kidneys (33–61%) and the islet self-dose (7.5–57%). In conclusion, all islet absorbed doses are low (<70 mGy), so even repeated imaging will hardly increase the risk on diabetes. PMID:28067253

  7. Towards a comprehensive CT image segmentation for thoracic organ radiation dose estimation and reporting

    NASA Astrophysics Data System (ADS)

    Lorenz, Cristian; Ruppertshofen, Heike; Vik, Torbjörn; Prinsen, Peter; Wiegert, Jens

    2014-03-01

    Administered dose of ionizing radiation during medical imaging is an issue of increasing concern for the patient, for the clinical community, and for respective regulatory bodies. CT radiation dose is currently estimated based on a set of very simplifying assumptions which do not take the actual body geometry and organ specific doses into account. This makes it very difficult to accurately report imaging related administered dose and to track it for different organs over the life of the patient. In this paper this deficit is addressed in a two-fold way. In a first step, the absorbed radiation dose in each image voxel is estimated based on a Monte-Carlo simulation of X-ray absorption and scattering. In a second step, the image is segmented into tissue types with different radio sensitivity. In combination this allows to calculate the effective dose as a weighted sum of the individual organ doses. The main purpose of this paper is to assess the feasibility of automatic organ specific dose estimation. With respect to a commercially applicable solution and respective robustness and efficiency requirements, we investigated the effect of dose sampling rather than integration over the organ volume. We focused on the thoracic anatomy as the exemplary body region, imaged frequently by CT. For image segmentation we applied a set of available approaches which allowed us to cover the main thoracic radio-sensitive tissue types. We applied the dose estimation approach to 10 thoracic CT datasets and evaluated segmentation accuracy and administered dose and could show that organ specific dose estimation can be achieved.

  8. A Feasibility Study of Fricke Dosimetry as an Absorbed Dose to Water Standard for 192Ir HDR Sources

    PubMed Central

    deAlmeida, Carlos Eduardo; Ochoa, Ricardo; de Lima, Marilene Coelho; David, Mariano Gazineu; Pires, Evandro Jesus; Peixoto, José Guilherme; Salata, Camila; Bernal, Mario Antônio

    2014-01-01

    High dose rate brachytherapy (HDR) using 192Ir sources is well accepted as an important treatment option and thus requires an accurate dosimetry standard. However, a dosimetry standard for the direct measurement of the absolute dose to water for this particular source type is currently not available. An improved standard for the absorbed dose to water based on Fricke dosimetry of HDR 192Ir brachytherapy sources is presented in this study. The main goal of this paper is to demonstrate the potential usefulness of the Fricke dosimetry technique for the standardization of the quantity absorbed dose to water for 192Ir sources. A molded, double-walled, spherical vessel for water containing the Fricke solution was constructed based on the Fricke system. The authors measured the absorbed dose to water and compared it with the doses calculated using the AAPM TG-43 report. The overall combined uncertainty associated with the measurements using Fricke dosimetry was 1.4% for k = 1, which is better than the uncertainties reported in previous studies. These results are promising; hence, the use of Fricke dosimetry to measure the absorbed dose to water as a standard for HDR 192Ir may be possible in the future. PMID:25521914

  9. Measurement of absorbed dose-to-water for an HDR {sup 192}Ir source with ionization chambers in a sandwich setup

    SciTech Connect

    Araki, Fujio; Kouno, Tomohiro; Ohno, Takeshi; Kakei, Kiyotaka; Yoshiyama, Fumiaki; Kawamura, Shinji

    2013-09-15

    Purpose: In this study, a dedicated device for ion chamber measurements of absorbed dose-to-water for a Nucletron microSelectron-v2 HDR {sup 192}Ir brachytherapy source is presented. The device uses two ionization chambers in a so-called sandwich assembly. Using this setup and by taking the average reading of the two chambers, any dose error due to difficulties in absolute positioning (centering) of the source in between the chambers is cancelled to first order. The method's accuracy was examined by comparing measurements with absorbed dose-to-water determination based on the AAPM TG-43 protocol.Methods: The optimal source-to-chamber distance (SCD) for {sup 192}Ir dosimetry was determined from ion chamber measurements in a water phantom. The {sup 192}Ir source was sandwiched between two Exradin A1SL chambers (0.057 cm{sup 3}) at the optimal SCD separation. The measured ionization was converted to the absorbed dose-to-water using a {sup 60}Co calibration factor and a Monte Carlo-calculated beam quality conversion factor, k{sub Q}, for {sup 60}Co to {sup 192}Ir. An uncertainty estimate of the proposed method was determined based on reproducibility of measurements at different institutions for the same type of source.Results: The optimal distance for the A1SL chamber measurements was determined to be 5 cm from the {sup 192}Ir source center, considering the depth dependency of k{sub Q} for {sup 60}Co to {sup 192}Ir and the chamber positioning. The absorbed dose to water measured at (5 cm, 90°) on the transverse axis was 1.3% lower than TG-43 values and its reproducibility and overall uncertainty were 0.8% and 1.7%, respectively. The measurement doses at anisotropic points agreed within 1.5% with TG-43 values.Conclusions: The ion chamber measurement of absorbed dose-to-water with a sandwich method for the {sup 192}Ir source provides a more accurate, direct, and reference dose compared to the dose-to-water determination based on air-kerma strength in the TG-43 protocol

  10. The experimental determination of C lambda using an absorbed dose calorimeter.

    PubMed

    Williams, P C

    1980-01-01

    The absorbed dose conversion factors, C lambda, were introduced, by Greene and Massey, as an interim measure until a primary standard for high energy photon dosimetry could be established. The theoretical basis of these factors has been discussed extensively and a more rigorous definition has emerged. Experiments have been carried out to determine the values of C lambda, for a Tufnol walled, Baldwin-Farmer ionisation chamber over a range of energies from cobalt-60 to 12 MV. The experimental results, based on measurements with a calorimeter, presented here support the more rigorous definition but it is shown that the values obtained depend, to a small extent, on the assumptions made about the detailed construction of the ionisation chamber for which C lambda is measured.

  11. Ingestion of Nevada Test Site Fallout: Internal dose estimates

    SciTech Connect

    Whicker, F.W.; Kirchner, T.B.; Anspaugh, L.R.

    1996-10-01

    This paper summarizes individual and collective dose estimates for the internal organs of hypothetical yet representative residents of selected communities that received measurable fallout from nuclear detonations at the Nevada Test Site. The doses, which resulted from ingestion of local and regional food products contaminated with over 20 radionuclides, were estimated with use of the PATHWAY food-chain-transport model to provide estimates of central tendency and uncertainty. The thyroid gland received much higher doses than other internal organs and tissues. In a avery few cases, infants might have received thyroid doses in excess of 1 Gy, depending on location, diet, and timing of fallout. {sup 131}I was the primary thyroid dose contributor, and fresh milk was the main exposure pathway. With the exception of the thyroid, organ doses from the ingestion pathway were much smaller (<3%) than those from external gamma exposure to deposited fallout. Doses to residents living closest to the Nevada Test Site were contributed mainly by a few fallout events; doses to more distantly located people were generally smaller, but a greater number of events provided measurable contributions. The effectiveness of different fallout events in producing internal organ doses through ingestion varied dramatically with seasonal timing of the test, with maximum dose per unit fallout occurring for early summer depositions when milk cows were on pasture and fresh, local vegetables were used. Within specific communities, internal doses differed by age, sex, and lifestyle. Collective internal dose estimates for specific geographic areas are provided.

  12. Direct measurement of absorbed dose to water in HDR {sup 192}Ir brachytherapy: Water calorimetry, ionization chamber, Gafchromic film, and TG-43

    SciTech Connect

    Sarfehnia, Arman; Kawrakow, Iwan; Seuntjens, Jan

    2010-04-15

    Purpose: Gafchromic film and ionometric calibration procedures for HDR {sup 192}Ir brachytherapy sources in terms of dose rate to water are presented and the experimental results are compared to the TG-43 protocol as well as with the absolute dose measurement results from a water calorimetry-based primary standard. Methods: EBT-1 Gafchromic films, an A1SL Exradin miniature Shonka thimble type chamber, and an SI HDR 1000 Plus well-type chamber (Standard Imaging, Inc., Middleton, WI) with an ADCL traceable S{sub k} calibration coefficient (following the AAPM TG-43 protocol) were used. The Farmer chamber and Gafchromic film measurements were performed directly in water. All results were compared to direct and absolute absorbed dose to water measurements from a 4 deg. C stagnant water calorimeter. Results: Based on water calorimetry, the authors measured the dose rate to water to be 361{+-}7 {mu}Gy/(h U) at a 55 mm source-to-detector separation. The dose rate normalized to air-kerma strength for all the techniques agree with the water calorimetry results to within 0.83%. The overall 1-sigma uncertainty on water calorimetry, ionization chamber, Gafchromic film, and TG-43 dose rate measurement amounts to 1.90%, 1.44%, 1.78%, and 2.50%, respectively. Conclusions: This work allows us to build a more realistic uncertainty estimate for absorbed dose to water determination using the TG-43 protocol. Furthermore, it provides the framework necessary for a shift from indirect HDR {sup 192}Ir brachytherapy dosimetry to a more accurate, direct, and absolute measurement of absorbed dose to water.

  13. Radiation Dosimetry for (177)Lu-PSMA I&T in Metastatic Castration-Resistant Prostate Cancer: Absorbed Dose in Normal Organs and Tumor Lesions.

    PubMed

    Okamoto, Shozo; Thieme, Anne; Allmann, Jakob; D'Alessandria, Calogero; Maurer, Tobias; Retz, Margitta; Tauber, Robert; Heck, Matthias M; Wester, Hans-Juergen; Tamaki, Nagara; Fendler, Wolfgang P; Herrmann, Ken; Pfob, Christian H; Scheidhauer, Klemens; Schwaiger, Markus; Ziegler, Sibylle; Eiber, Matthias

    2017-03-01

    Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy is increasingly used in metastatic castration-resistant prostate cancer. We aimed to estimate the absorbed doses for normal organs and tumor lesions using (177)Lu-PSMA I&T (I&T is imaging and therapy) in patients undergoing up to 4 cycles of radioligand therapy. Results were compared with pretherapeutic Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBEDCC)] ((68)Ga-PSMA-HBED-CC) PET. Methods: A total of 34 cycles in 18 patients were analyzed retrospectively. In 15 patients the first, in 9 the second, in 5 the third, and in 5 the fourth cycle was analyzed, respectively. Whole-body scintigraphy was performed at least between 30-120 min, 24 h, and 6-8 d after administration. Regions of interest covering the whole body, organs, and up to 4 tumor lesions were drawn. Organ and tumor masses were derived from pretherapeutic (68)Ga-PSMA-HBED-CC PET/CT. Absorbed doses for individual cycles were calculated using OLINDA/EXM. SUVs from pretherapeutic PET were compared with absorbed doses and with change of SUV. Results: The mean whole-body effective dose for all cycles was 0.06 ± 0.03 Sv/GBq. The mean absorbed organ doses were 0.72 ± 0.21 Gy/GBq for the kidneys; 0.12 ± 0.06 Gy/GBq for the liver; and 0.55 ± 0.14 Gy/GBq for the parotid, 0.64 ± 0.40 Gy/GBq for the submandibular, and 3.8 ± 1.4 Gy/GBq for the lacrimal glands. Absorbed organ doses were relatively constant among the 4 different cycles. Tumor lesions received a mean absorbed dose per cycle of 3.2 ± 2.6 Gy/GBq (range, 0.22-12 Gy/GBq). Doses to tumor lesions gradually decreased, with 3.5 ± 2.9 Gy/GBq for the first, 3.3 ± 2.5 Gy/GBq for the second, 2.7 ± 2.3 Gy/GBq for the third, and 2.4 ± 2.2 Gy/GBq for the fourth cycle. SUVs of pretherapeutic PET moderately correlated with absorbed dose (r = 0.44, P < 0.001 for SUVmax; r = 0.43, P < 0.001 for SUVmean) and moderately correlated with the change of SUV (r = 0.478, P < 0.001 for SUVmax, and r = 0.50, P < 0

  14. Simple methods for the estimation of dose distributions, organ doses and energy imparted in paediatric radiology.

    PubMed

    Almén, A; Nilsson, M

    1996-07-01

    The energy imparted and the effective dose can both be used to describe the risk to the patient in diagnostic radiology. Simple methods must be employed to determine these quantities in clinical situations. Methods using measured relative depth-dose distributions are presented and evaluated here. Measurements of depth-dose distributions for x-ray beams were performed with an ionization chamber, a diode and a number of TL dosimeters. The energy imparted was calculated from measurements with both phantoms and patients. The method of calculating the mean absorbed dose to organs was applied to pelvis and lumbar spine examinations. TL dosimeters were found to be an appropriate detector for measuring depth-dose distributions. When calculating the energy imparted the entrance beam area must be accurately known. The mean absorbed dose to organs can be derived from measured relative depth-dose curves if accurate information on entrance beam position and area is available for the particular examination technique used. The advantage of these methods is that the dose distribution is measured for the photon beam used for the examination of the patients.

  15. Long-term stability of liquid ionization chambers with regard to their qualification as local reference dosimeters for low dose-rate absorbed dose measurements in water.

    PubMed

    Bahar-Gogani, J; Grindborg, J E; Johansson, B E; Wickman, G

    2001-03-01

    The long-term sensitivity and calibration stability of liquid ionization chambers (LICs) has been studied at a local and a secondary standards dosimetry laboratory over a period of 3 years. The chambers were transported several times by mail between the two laboratories for measurements. The LICs used in this work are designed for absorbed dose measurements in the dose rate region of 0.1-100 mGy min(-1) and have a liquid layer thickness of 1 mm and a sensitive volume of 16.2 mm3. The liquids used as sensitive media in the chambers are mixtures of isooctane (C8H18) and tetramethylsilane (Si(CH3)4) in different proportions (about 2 to 1). Operating at a polarizing voltage of 300 V the leakage current of the chambers was stable and never exceeded 3% of the observable current at a dose rate of about 1 mGy min(-1). The volume sensitivity of the chambers was measured to be of the order of 10(-9) C Gy(-1) mm3. No systematic changes in the absorbed dose to water calibration was observed for any of the chambers during the test period (sigma < 0.2%). Variations in chamber dose response with small changes in the polarizing voltage as well as sensitivity changes with accumulated absorbed dose were also investigated. Measurements showed that the LIC response varies by 0.15% per 1% change in applied voltage around 300 V. No significant change could be observed in the LIC sensitivity after a single absorbed dose of 15 kGy. The results indicate that the LIC can be made to serve as a calibration transfer instrument and a reference detector for absorbed dose to water determinations providing good precision and long-term reproducibility.

  16. A graphite calorimeter for absolute measurements of absorbed dose to water: application in medium-energy x-ray filtered beams.

    PubMed

    Pinto, M; Pimpinella, M; Quini, M; D'Arienzo, M; Astefanoaei, I; Loreti, S; Guerra, A S

    2016-02-21

    The Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI) has designed and built a graphite calorimeter that, in a water phantom, has allowed the determination of the absorbed dose to water in medium-energy x-rays with generating voltages from 180 to 250 kV. The new standard is a miniaturized three-bodies calorimeter, with a disc-shaped core of 21 mm diameter and 2 mm thickness weighing 1.134 g, sealed in a PMMA waterproof envelope with air-evacuated gaps. The measured absorbed dose to graphite is converted into absorbed dose to water by means of an energy-dependent conversion factor obtained from Monte Carlo simulations. Heat-transfer correction factors were determined by FEM calculations. At a source-to-detector distance of 100 cm, a depth in water of 2 g cm(-2), and at a dose rate of about 0.15 Gy min(-1), results of calorimetric measurements of absorbed dose to water, D(w), were compared to experimental determinations, D wK, obtained via an ionization chamber calibrated in terms of air kerma, according to established dosimetry protocols. The combined standard uncertainty of D(w) and D(wK) were estimated as 1.9% and 1.7%, respectively. The two absorbed dose to water determinations were in agreement within 1%, well below the stated measurement uncertainties. Advancements are in progress to extend the measurement capability of the new in-water-phantom graphite calorimeter to other filtered medium-energy x-ray qualities and to reduce the D(w) uncertainty to around 1%. The new calorimeter represents the first implementation of in-water-phantom graphite calorimetry in the kilovoltage range and, allowing independent determinations of D(w), it will contribute to establish a robust system of absorbed dose to water primary standards for medium-energy x-ray beams.

  17. MO-AB-BRA-03: Calorimetry-Based Absorbed Dose to Water Measurements Using Interferometry

    SciTech Connect

    Flores-Martinez, E; Malin, M; DeWerd, L

    2015-06-15

    Purpose: Interferometry-based calorimetry is a novel technique to measure radiation-induced temperature changes allowing the measurement of absorbed dose to water (ADW). There are no mechanical components in the field. This technique also has the possibility of obtaining 2D dose distributions. The goal of this investigation is to calorimetrically-measure doses between 2.5 and 5 Gy over a single projection in a photon beam using interferometry and compare the results with doses calculated using the TG-51 linac calibration. Methods: ADW was determined by measuring radiation-induced phase shifts (PSs) of light passing through water irradiated with a 6 MV photon beam. A 9×9×9 cm{sup 3} glass phantom filled with water and placed in an arm of a Michelson interferometer was irradiated with 300, 400, 500 and 600 monitor units. The whole system was thermally insulated to achieve sufficient passive temperature control. The depth of measurement was 4.5 cm with a field size of 7×7 cm{sup 2}. The intensity of the fringe pattern was monitored with a photodiode and used to calculate the time-dependent PS curve. Data was acquired 60 s before and after the irradiation. The radiation-induced PS was calculated by taking the difference in the pre- and post-irradiation drifts extrapolated to the midpoint of the irradiation. Results were compared to computed doses. Results: Average comparison of calculated ADW values with interferometry-measured values showed an agreement to within 9.5%. k=1 uncertainties were 4.3% for calculations and 14.7% for measurements. The dominant source of uncertainty for the measurements was a temperature drift of about 30 µK/s caused by heat conduction from the interferometer’s surroundings. Conclusion: This work presented the first absolute ADW measurements using interferometry in the dose range of linac-based radiotherapy. Future work to improve measurements’ reproducibility includes the implementation of active thermal control techniques.

  18. Boundary Electron and Beta Dosimetry-Quantification of the Effects of Dissimilar Media on Absorbed Dose

    NASA Astrophysics Data System (ADS)

    Nunes, Josane C.

    1991-02-01

    This work quantifies the changes effected in electron absorbed dose to a soft-tissue equivalent medium when part of this medium is replaced by a material that is not soft -tissue equivalent. That is, heterogeneous dosimetry is addressed. Radionuclides which emit beta particles are the electron sources of primary interest. They are used in brachytherapy and in nuclear medicine: for example, beta -ray applicators made with strontium-90 are employed in certain ophthalmic treatments and iodine-131 is used to test thyroid function. More recent medical procedures under development and which involve beta radionuclides include radioimmunotherapy and radiation synovectomy; the first is a cancer modality and the second deals with the treatment of rheumatoid arthritis. In addition, the possibility of skin surface contamination exists whenever there is handling of radioactive material. Determination of absorbed doses in the examples of the preceding paragraph requires considering boundaries of interfaces. Whilst the Monte Carlo method can be applied to boundary calculations, for routine work such as in clinical situations, or in other circumstances where doses need to be determined quickly, analytical dosimetry would be invaluable. Unfortunately, few analytical methods for boundary beta dosimetry exist. Furthermore, the accuracy of results from both Monte Carlo and analytical methods has to be assessed. Although restricted to one radionuclide, phosphorus -32, the experimental data obtained in this work serve several purposes, one of which is to provide standards against which calculated results can be tested. The experimental data also contribute to the relatively sparse set of published boundary dosimetry data. At the same time, they may be useful in developing analytical boundary dosimetry methodology. The first application of the experimental data is demonstrated. Results from two Monte Carlo codes and two analytical methods, which were developed elsewhere, are compared

  19. Verification of absorbed dose rates in reference beta radiation fields: Measurements with an extrapolation chamber and radiochromic film.

    PubMed

    Reynaldo, S R; Benavente, J A; Da Silva, T A

    2016-11-01

    Beta Secondary Standard 2 (BSS 2) provides beta radiation fields with certified values of absorbed dose to tissue and the derived operational radiation protection quantities. As part of the quality assurance, the reliability of the CDTN BSS2 system was verified through measurements in the (90)Sr/(90)Y and (85)Kr beta radiation fields. Absorbed dose rates and their angular variation were measured with a 23392 model PTW extrapolation chamber and with Gafchromic radiochromic films on a PMMA slab phantom. The feasibility of using both methods was analyzed.

  20. Transcriptional Response in Mouse Thyroid Tissue after 211At Administration: Effects of Absorbed Dose, Initial Dose-Rate and Time after Administration

    PubMed Central

    Rudqvist, Nils; Spetz, Johan; Schüler, Emil; Parris, Toshima Z.; Langen, Britta; Helou, Khalil; Forssell-Aronsson, Eva

    2015-01-01

    Background 211At-labeled radiopharmaceuticals are potentially useful for tumor therapy. However, a limitation has been the preferential accumulation of released 211At in the thyroid gland, which is a critical organ for such therapy. The aim of this study was to determine the effect of absorbed dose, dose-rate, and time after 211At exposure on genome-wide transcriptional expression in mouse thyroid gland. Methods BALB/c mice were i.v. injected with 1.7, 7.5 or 100 kBq 211At. Animals injected with 1.7 kBq were killed after 1, 6, or 168 h with mean thyroid absorbed doses of 0.023, 0.32, and 1.8 Gy, respectively. Animals injected with 7.5 and 100 kBq were killed after 6 and 1 h, respectively; mean thyroid absorbed dose was 1.4 Gy. Total RNA was extracted from pooled thyroids and the Illumina RNA microarray platform was used to determine mRNA levels. Differentially expressed transcripts and enriched GO terms were determined with adjusted p-value <0.01 and fold change >1.5, and p-value <0.05, respectively. Results In total, 1232 differentially expressed transcripts were detected after 211At administration, demonstrating a profound effect on gene regulation. The number of regulated transcripts increased with higher initial dose-rate/absorbed dose at 1 or 6 h. However, the number of regulated transcripts decreased with mean absorbed dose/time after 1.7 kBq 211At administration. Furthermore, similar regulation profiles were seen for groups administered 1.7 kBq. Interestingly, few previously proposed radiation responsive genes were detected in the present study. Regulation of immunological processes were prevalent at 1, 6, and 168 h after 1.7 kBq administration (0.023, 0.32, 1.8 Gy). PMID:26177204

  1. A Bayesian Semiparametric Model for Radiation Dose-Response Estimation.

    PubMed

    Furukawa, Kyoji; Misumi, Munechika; Cologne, John B; Cullings, Harry M

    2016-06-01

    In evaluating the risk of exposure to health hazards, characterizing the dose-response relationship and estimating acceptable exposure levels are the primary goals. In analyses of health risks associated with exposure to ionizing radiation, while there is a clear agreement that moderate to high radiation doses cause harmful effects in humans, little has been known about the possible biological effects at low doses, for example, below 0.1 Gy, which is the dose range relevant to most radiation exposures of concern today. A conventional approach to radiation dose-response estimation based on simple parametric forms, such as the linear nonthreshold model, can be misleading in evaluating the risk and, in particular, its uncertainty at low doses. As an alternative approach, we consider a Bayesian semiparametric model that has a connected piece-wise-linear dose-response function with prior distributions having an autoregressive structure among the random slope coefficients defined over closely spaced dose categories. With a simulation study and application to analysis of cancer incidence data among Japanese atomic bomb survivors, we show that this approach can produce smooth and flexible dose-response estimation while reasonably handling the risk uncertainty at low doses and elsewhere. With relatively few assumptions and modeling options to be made by the analyst, the method can be particularly useful in assessing risks associated with low-dose radiation exposures.

  2. Radiation dose estimates for C-11 iomazenil, a benzodiazepine receptor radioligand

    SciTech Connect

    Sparks, R.B.; Dey, H.M.; Siebyl, I.B.

    1994-05-01

    SPECT imaging of the brain with I-123 iomazenil has shown avid uptake of the radioligand in a distribution consistent with benzodiazepine receptor binding. It was desirable to radiolabel this compound with a positron emitting radionuclide so that quantitation of the receptor density could be assessed with PET imaging. Radiation dose estimates for C-11 iomazenil were calculated prior to obtaining Institutional Review Board approval of this procedure. A previously published multicompartmental model was used as the biological model for estimating residence times associated with the C-11 labeled iomazenil. According to this model, 85-90% is excreted in the urine and 10-15% in the feces. A dynamic, voiding urinary bladder model was utilized for activity excreted renally and the ICRP 30 gastrointestinal tract kinetic model was used for activity excreted via the hepatobiliary system. Absorbed doses from C-11 (I-123) iomazenil to the urinary bladder were calculated to be 0.099 mGy/MBq (0.19 mGy/MBq) for a 4.8 hour bladder voiding interval. Shortening the bladder voiding interval to 2.0 hours had little effect on the bladder wall dose (0.095 mGy/MBq). However, a 30-minute void interval was estimated to lower the bladder wall dose substantially (0.045 mGy/MBq). Absorbed dose to the kidney was higher for C-11 iomazenil (0.054 vs 0.031 mGy/MBq) than for I-123 iomazenil due to rapid, early renal excretion of this very short-lived positron emitter. Doses to the gastrointestinal tract were estimated to be 4- to 20-fold lower for C-11 iomazenil compared to I-123 iomazenil. Overall, labeling iomazenil with C-11 rather than I-123 greatly reduces the radiation dose, per unit administered, to all organs except the kidneys.

  3. Analysis of the Body Distribution of Absorbed Dose in the Organs of Three Species of Fish from Sepetiba Bay

    NASA Astrophysics Data System (ADS)

    Pereira, Wagner de S.; Kelecom, Alphonse; dos Santos Gouvea, Rita de Cássia; Py Júnior, Delcy de Azevedo

    2008-08-01

    The body distribution of Polonium-210 in three fishes from the Sepetiba Bay (Macrodon ancylodon, Micropogonias furnieri and Mugil curema) has been studied under the approach of the Department of Energy of the United States of America (DOE) that set the limit of absorbed dose rate in biota equal to 3.5×103 μGy/y, and that also established the relation between dose rate (D) and radionuclide concentration (c) on a fish muscle fresh weight basis, as follows: D = 5.05 E×N×C, assuming that the radionuclide distribution is homogenous among organs. Two hypotheses were tested here, using statistical tools: 1) is the body distribution of absorbed dose homogenous among organs? and 2) is the body distribution of absorbed dose identical among studied fishes? It was concluded, as expected, that the distribution among organs is heterogeneous; but, unexpectedly, that the three fishes display identical body distribution pattern, although they belong to different trophic levels. Hence, concerning absorbed dose calculation, the statement that data distribution is homogenous must be understood merely as an approximation, at least in the case of Polonium-210.

  4. Analysis of the Body Distribution of Absorbed Dose in the Organs of Three Species of Fish from Sepetiba Bay

    SciTech Connect

    Pereira, Wagner de S; Kelecom, Alphonse; Santos Gouvea, Rita de Cassia dos; Azevedo Py Junior, Delcy de

    2008-08-07

    The body distribution of Polonium-210 in three fishes from the Sepetiba Bay (Macrodon ancylodon, Micropogonias furnieri and Mugil curema) has been studied under the approach of the Department of Energy of the United States of America (DOE) that set the limit of absorbed dose rate in biota equal to 3.5x10{sup 3} {mu}Gy/y, and that also established the relation between dose rate (D) and radionuclide concentration (c) on a fish muscle fresh weight basis, as follows: D = 5.05 ExNxC, assuming that the radionuclide distribution is homogenous among organs. Two hypotheses were tested here, using statistical tools: 1) is the body distribution of absorbed dose homogenous among organs? and 2) is the body distribution of absorbed dose identical among studied fishes? It was concluded, as expected, that the distribution among organs is heterogeneous; but, unexpectedly, that the three fishes display identical body distribution pattern, although they belong to different trophic levels. Hence, concerning absorbed dose calculation, the statement that data distribution is homogenous must be understood merely as an approximation, at least in the case of Polonium-210.

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

    SciTech Connect

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

    2014-07-15

    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. The 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

  6. Methodology for Estimating Ingestion Dose for Emergency Response at SRS

    SciTech Connect

    Simpkins, A.A.

    2003-07-21

    At the Savannah River Site (SRS), emergency response computer models are used to estimate dose following releases of radioactive materials to the environment. Downwind air and ground concentrations and their associated doses from inhalation and ground shine pathways are estimated. The emergency response model (PUFF-PLUME) uses real-time data to track either instantaneous (puff) or continuous (plume) releases. A site-specific ingestion dose model was developed for use with PUFF-PLUME that includes the following ingestion dose pathways pertinent to the surrounding SRS area: milk, beef, water, and fish. The model is simplistic and can be used with existing code output.

  7. Detailed Distribution Map of Absorbed Dose Rate in Air in Tokatsu Area of Chiba Prefecture, Japan, Constructed by Car-Borne Survey 4 Years after the Fukushima Daiichi Nuclear Power Plant Accident

    PubMed Central

    Inoue, Kazumasa; Arai, Moeko; Fujisawa, Makoto; Saito, Kyouko; Fukushi, Masahiro

    2017-01-01

    A car-borne survey was carried out in the northwestern, or Tokatsu, area of Chiba Prefecture, Japan, to make a detailed distribution map of absorbed dose rate in air four years after the Fukushima Daiichi Nuclear Power Plant accident. This area was chosen because it was the most heavily radionuclide contaminated part of Chiba Prefecture and it neighbors metropolitan Tokyo. Measurements were performed using a 3-in × 3-in NaI(Tl) scintillation spectrometer in June 2015. The survey route covered the whole Tokatsu area which includes six cities. A heterogeneous distribution of absorbed dose rate in air was observed on the dose distribution map. Especially, higher absorbed dose rates in air exceeding 80 nGy h-1 were observed along national roads constructed using high porosity asphalt, whereas lower absorbed dose rates in air were observed along local roads constructed using low porosity asphalt. The difference between these asphalt types resulted in a heterogeneous dose distribution in the Tokatsu area. The mean of the contribution ratio of artificial radionuclides to absorbed dose rate in air measured 4 years after the accident was 29% (9–50%) in the Tokatsu area. The maximum absorbed dose rate in air, 201 nGy h-1 was observed at Kashiwa City. Radiocesium was deposited in the upper 1 cm surface layer of the high porosity asphalt which was collected in Kashiwa City and the environmental half-life of the absorbed dose rate in air was estimated to be 1.7 years. PMID:28129382

  8. Absorbed dose measurements of a handheld 50 kVP X-ray source in water with thermoluminescence dosemeters.

    PubMed

    Soares, Christopher; Drupieski, Chris; Wingert, Brian; Pritchett, Garey; Pagonis, Vasilis; O'Brien, Michelle; Sliski, Alan; Bilski, Pawel; Olko, Pawel

    2006-01-01

    Absorbed dose rate measurements of a 50 kV(p) handheld X-ray probe source in a water phantom are described. The X-ray generator is capable of currents of up to 40 microA, and is designed for cranial brachytherapy and intraoperative applications with applicators. The measurements were performed in a computer-controlled water phantom in which both the source and the detectors are mounted. Two different LiF thermoluminescence dosemeter (TLD) phosphors were employed for the measurements, MTS-N (LiF:Mg,Ti) and MCP-N (LiF:Mg,Cu,P). Two small ionisation chambers (0.02 and 0.0053 cm(3)) were also employed. The TLDs and chambers were positioned in watertight mounts made of water-equivalent plastic. The chambers were calibrated in terms of air-kerma rate, and conventional protocols were used to convert the measurements to absorbed dose rate. The TLDs were calibrated at National Institute of Standards and Technology (NIST) in terms of absorbed dose rate using a (60)Co teletherapy beam and narrow-spectrum X-ray beams. For the latter, absorbed dose was inferred from air-kerma rate using calculated air-kerma-to-dose conversion factors. The reference points of the various detectors were taken as the center of the TLD volumes and the entrance windows of the ionisation chambers. Measurements were made at distances of 3-45 mm from the detector reference point to the source center. In addition, energy dependence of response measurements of the TLDs used was made using NIST reference narrow spectrum X-ray beams. Measurement results showed reasonable agreement in absorbed dose rate determined from the energy dependence corrected TLD readings and from the ionisation chambers. Volume averaging effects of the TLDs at very close distances to the source were also evident.

  9. 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.

  10. Sample Based Unit Liter Dose Estimates

    SciTech Connect

    JENSEN, L.

    2000-04-13

    The Tank Waste Characterization Program has taken many core samples, grab samples, and auger samples from the single-shell and double-shell tanks during the past 10 years. Consequently, the amount of sample data available has increased, both in terms of quantity of sample results and the number of tanks characterized. More and better data is available than when the current radiological and toxicological source terms used in the Basis for Interim Operation (BIO) (FDH 1999a) and the Final Safety Analysis Report (FSAR) (FDH 1999b) were developed. The Nuclear Safety and Licensing (NS and L) organization wants to use the new data to upgrade the radiological and toxicological source terms used in the BIO and FSAR. The NS and L organization requested assistance in producing a statistically based process for developing the source terms. This report describes the statistical techniques used and the assumptions made to support the development of a new radiological source term for liquid and solid wastes stored in single-shell and double-shell tanks. The results given in this report are a revision to similar results given in an earlier version of the document (Jensen and Wilmarth 1999). The main difference between the results in this document and the earlier version is that the dose conversion factors (DCF) for converting {mu}Ci/g or {mu}Ci/L to Sv/L (sieverts per liter) have changed. There are now two DCFs, one based on ICRP-68 and one based on ICW-71 (Brevick 2000).

  11. The multichannel clinic dosimeter for the multiparameter direct control system of absorbed dose in areas of medical interest

    NASA Astrophysics Data System (ADS)

    Sumin, A. V.; Abalakin, I. N.; Medvedkov, A. M.; Smirnova, M. O.; Chernyaev, A. P.; Samosadny, V. T.

    2017-01-01

    The basic principle of radiation therapy is the treatment of a tumor with the maximum reduction in radiation doses to normal organs and tissues. You must implement a plan of irradiation, which will provide the recommended absorbed dose of ionizing radiation in the tumor volume and minimal dose to the tumor surrounding normal tissues and critical organs, at least, less than the tolerant dose for these tissues. There are very stringent requirements on the accuracy of realization of the values of doses. Therefore, the value of the dose must be controlled during the irradiation session. In this case, we will have the opportunity to interrupt the session, and to adjust the program of irradiation to avoid bad consequences. For these purposes, “NIITFA” has developed and manufactured multi-channel dosimeter MKD-04. Specialists Held the first technical and clinical testing of the device, the results confirm the high level capabilities of the dosimeter.

  12. Effective dose estimation during conventional and CT urography

    NASA Astrophysics Data System (ADS)

    Alzimami, K.; Sulieman, A.; Omer, E.; Suliman, I. I.; Alsafi, K.

    2014-11-01

    Intravenous urography (IVU) and CT urography (CTU) are efficient radiological examinations for the evaluation of the urinary system disorders. However patients are exposed to a significant radiation dose. The objectives of this study are to: (i) measure and compare patient radiation dose by computed tomography urography (CTU) and conventional intravenous urography (IVU) and (ii) evaluate organ equivalent dose and cancer risks from CTU and IVU imaging procedures. A total of 141 patients were investigated. A calibrated CT machine (Siemens-Somatom Emotion duo) was used for CTU, while a Shimadzu X ray machine was used for IVU. Thermoluminescence dosimeters (TLD-GR200A) were used to measure patients' entrance surface doses (ESD). TLDs were calibrated under reproducible reference conditions. Patients radiation dose values (DLP) for CTU were 172±61 mGy cm, CTDIvol 4.75±2 mGy and effective dose 2.58±1 mSv. Patient cancer probabilities were estimated to be 1.4 per million per CTU examination. Patients ESDs values for IVU were 21.62±5 mGy, effective dose 1.79±1 mSv. CT involves a higher effective dose than IVU. In this study the radiation dose is considered low compared to previous studies. The effective dose from CTU procedures was 30% higher compared to IVU procedures. Wide dose variation between patient doses suggests that optimization is not fulfilled yet.

  13. Size estimates for intervening CIV absorbers from high-resolution spectroscopy of APM 0827+5255

    NASA Astrophysics Data System (ADS)

    Tzanavaris, Panayiotis; Carswell, Robert F.

    2003-04-01

    A new analysis of Keck/HIRES observations of the broad absorption line quasi-stellar object (QSO) APM 0827+5255 indicates that a number of intervening CIV absorbers give rise to absorption lines for which the observed optical depths for the 1548, 1550 Å doublet components are not in the expected 2:1 ratio. To compensate for the effect, a local adjustment of the zero-level is required. We model this effect as coverage of one line of sight to this gravitationally lensed QSO and perform a set of simulations to select a sample of lines for which our model provides an explanation for the effect. We use lines in this sample to obtain estimates for minimum CIV absorber sizes from total coverage and the separations of the lines of sight for a range of lens redshifts, zl, and two cosmologies. We also obtain best estimates for overall sizes from a statistical `hit and miss' approach. For zl= 0.7 our results set a lower limit to sizes of CIV absorbers of ~0.3 h-172 kpc (~0.5 h-172 kpc) for ΩM= 1, ΩΛ= 0 (ΩM= 0.3, ΩΛ= 0.7), in agreement with other results from similar work but are limited by sample size and the uncertainty in zl. Our method can be used to detect lensed QSOs and to probe absorber sizes when separate spectra cannot be obtained for each line of sight.

  14. 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.

  15. A new gel using super absorbent polymer for mapping the spatial dose distributions of electron beams by MR imager.

    PubMed

    Hiraoka, T; Hoshino, K; Kawashima, K; Kato, H; Tateno, Y

    1993-01-01

    A technique for mapping the spatial dose distribution with a magnetic resonance imager is presented. A ferrous sulphate solution with sulfuric acid was used as the detecting medium for radiation dose. To make a gel of the solution for filling up a cubic phantom, we developed a new gel component that is combined with a super absorbent polymer (Sumikagel N-100) and a cross-linked dextran gel (Sephadex G-200). In order to make the application for radiation treatment planning, mapping of the dose distribution was carried out using a Unix computer.

  16. Absorbed dose distributions for X-ray beams and beams of electrons from the Therac 20 Saturne linear accelerator.

    PubMed

    Tronc, D; Noël, A

    1978-11-01

    After a brief description of the Therac 20 Saturne linear accelerator a complete set of absorbed-dose distribution values is given. These values define the depths on the axis as a function of the depth dose and define the penumbra (as characterized by the positions of the intersections of the isodose curves with planes parallel to the phantom surface) for beams of X-rays and for beams of electrons. Tissue-maximum ratios are given for beams of X-rays. Analytical values for the electron depth dose curve are compared with the values obtained on the Sagittaire linear accelerator.

  17. Method for Fast CT/SPECT-Based 3D Monte Carlo Absorbed Dose Computations in Internal Emitter Therapy

    PubMed Central

    Wilderman, S. J.; Dewaraja, Y. K.

    2010-01-01

    The DPM (Dose Planning Method) Monte Carlo electron and photon transport program, designed for fast computation of radiation absorbed dose in external beam radiotherapy, has been adapted to the calculation of absorbed dose in patient-specific internal emitter therapy. Because both its photon and electron transport mechanics algorithms have been optimized for fast computation in 3D voxelized geometries (in particular, those derived from CT scans), DPM is perfectly suited for performing patient-specific absorbed dose calculations in internal emitter therapy. In the updated version of DPM developed for the current work, the necessary inputs are a patient CT image, a registered SPECT image, and any number of registered masks defining regions of interest. DPM has been benchmarked for internal emitter therapy applications by comparing computed absorption fractions for a variety of organs using a Zubal phantom with reference results from the Medical Internal Radionuclide Dose (MIRD) Committee standards. In addition, the β decay source algorithm and the photon tracking algorithm of DPM have been further benchmarked by comparison to experimental data. This paper presents a description of the program, the results of the benchmark studies, and some sample computations using patient data from radioimmunotherapy studies using 131I. PMID:20305792

  18. Absorbed photon dose measurement and calculation for some patient organs examined by computed tomography

    NASA Astrophysics Data System (ADS)

    Shousha, Hany A.

    Patient doses from computed tomography (CT) examinations are usually expressed in terms of dose index, organ doses, and effective dose. The CT dose index (CTDI) can be measured free-in-air or in a CT dosimetry phantom. Organ doses can be measured directly in anthropomorphic Rando phantoms using thermoluminescent detectors. Organ doses can also be calculated by the Monte Carlo method utilizing measured CTDI values. In this work, organ doses were assessed for three main CT examinations: head, chest, and abdomen, using the different mentioned methods. Results of directly measured doses were compared with calculated doses for different organs in the study, and also compared with published international studies.

  19. Evaluation of absorbed dose in irradiated sugar-containing plant material (peony roots) by an ESR method

    NASA Astrophysics Data System (ADS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2015-12-01

    The relationship between electron spin resonance (ESR) signal intensity of irradiated plant materials and sugar content was investigated by spectral analysis using peony roots. A weak background signal near g=2.005 was observed in the roots. After a 10 kGy irradiation, the ESR line broadened and the intensity increased, and the spectral characteristics were similar to a typical spectrum of irradiated food containing crystalline sugars. The free radical concentration was nearly stable 30 days after irradiation. The spectrum of peony root 30 days after irradiation was simulated using the summation of the intensities of six assumed components: radical signals derived from (a) sucrose, (b) glucose, (c) fructose, (d) cellulose, (e) the background signal near g=2.005 and (f) unidentified component. The simulated spectra using the six components were in agreement with the observed sample spectra. The intensity of sucrose radical signal in irradiated samples increased proportionally up to 20 kGy. In addition, the intensity of sucrose radical signals was strongly correlated with the sucrose contents of the samples. The results showed that the radiation sensitivity of sucrose in peony roots was influenced little by other plant constituents. There was also a good correlation between the total area of the spectra and the sucrose content, because the sucrose content was higher than that of other sugars in the samples. In peony roots, estimation of the absorbed dose from the ESR signal intensity may be possible by a calibration method based on the sucrose content.

  20. Treatment of small-cell lung cancer xenografts with iodine-313-anti-neural cell adhesion molecule monoclonal antibody and evaluation of absorbed dose in tissue

    SciTech Connect

    Hosono, Makoto; Endo, Keigo; Hosono, Masako N.

    1994-02-01

    Human small-cell lung cancer (SCLC) is considered a feasible target for immunotherapy using a radiolabeled monoclonal antibody (Mab). A murine Mab, NE150 (IgG1), reacts with the neural cell adhesion molecule, which is identical to cluster 1 antigen of SCLC. To estimate their therapeutic effects, NE150 and an isotype-matched control Mab were labeled with {sup 131}I and administered intravenously as a single dose into athymic mice inoculated with a NCI-H69 SCLC xenograft. The absorbed dose in organs was also examined based upon a long-term biodistribution study of {sup 131}I-NE150. Tumors initial volume 563.4 {plus_minus} 223.5 mm{sup 3} treated with 11.1 MBq (300 {mu}Ci) of {sup 131}I-NE150 diminished and became invisible at days 30-33, demonstrating a 60-day mean growth delay to reach a tripled initial volume compared with sham-treated tumors. Cumulative absorbed doses were estimated to be 2310, 410, 500, 330, and 790 cGy for the tumor, liver, kidney, spleen and lung, respectively. Iodine-131-NE150 had potent therapeutic effects against SCLC transplants in athymic mice, however, careful assessment of the side effects, improvement of radioiodination and chimerization of the Mab might be necessary to achieve efficient targeting in clinical therapeutic applications. 25 refs., 2 figs., 3 tabs.

  1. Estimation of dose to man from environmental tritium

    SciTech Connect

    Rohwer, P S; Etnier, E L

    1980-01-01

    Factors important for characterization of tritium in environmental pathways leading to exposure of man are reviewed and quantification of those factors is discussed. Parameters characterizing the behavior of tritium in man are also subjected to review. Factors to be discussed include organic binding, bioaccumulation, quality factor and transmutation. A variety of models are presently in use to estimate dose to man from environmental releases of tritium. Results from four representative models are compared and discussed. Site-specific information is always preferable when parameterizing models to estimate dose to man. There may be significant differences in dose potential among geographic regions due to variable factors. An example of one such factor examined is absolute humidity. It is concluded that adequate methodologies exist for estimation of dose to man from environmental tritium although a number of areas are identified where additional tritium research is desirable.

  2. First international comparison of primary absorbed dose to water standards in the medium-energy X-ray range

    NASA Astrophysics Data System (ADS)

    Büermann, Ludwig; Guerra, Antonio Stefano; Pimpinella, Maria; Pinto, Massimo; de Pooter, Jacco; de Prez, Leon; Jansen, Bartel; Denoziere, Marc; Rapp, Benjamin

    2016-01-01

    This report presents the results of the first international comparison of primary measurement standards of absorbed dose to water for the medium-energy X-ray range. Three of the participants (VSL, PTB, LNE-LNHB) used their existing water calorimeter based standards and one participant (ENEA) recently developed a new standard based on a water-graphite calorimeter. The participants calibrated three transfer chambers of the same type in terms of absorbed dose to water (NDw) and in addition in terms of air kerma (NK) using the CCRI radiation qualities in the range 100 kV to 250 kV. The additional NK values were intended to be used for a physical analysis of the ratios NDw/NK. All participants had previously participated in the BIPM.RI(I)-K3 key comparison of air kerma standards. Ratios of pairs of NMI's NK results of the current comparison were found to be consistent with the corresponding key comparison results within the expanded uncertainties of 0.6 % - 1 %. The NDw results were analysed in terms of the degrees of equivalence with the comparison reference values which were calculated for each beam quality as the weighted means of all results. The participant's results were consistent with the reference value within the expanded uncertainties. However, these expanded uncertainties varied significantly and ranged between about 1-1.8 % for the water calorimeter based standards and were estimated at 3.7 % for the water-graphite calorimeter. It was shown previously that the ratios NDw/NK for the type of ionization chamber used as transfer chamber in this comparison were very close (within less than 1 %) to the calculated values of (bar muen/ρ)w,ad, the mean values of the water-to-air ratio of the mass-energy-absorption coefficients at the depth d in water. Some of the participant's results deviated significantly from the expected behavior. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of

  3. Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU adult reference computational phantoms.

    PubMed

    Sato, Tatsuhiko; Endo, Akira; Sihver, Lembit; Niita, Koji

    2011-03-01

    Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients in the units of Gy.cm(2) and Sv.cm(2), respectively, and cosmic-ray fluxes around spacecrafts in the unit of cm(-2) s(-1). The dose conversion coefficients employed in the calculation were evaluated using the general-purpose particle and heavy ion transport code system PHITS coupled to the male and female adult reference computational phantoms, which were released as a common ICRP/ICRU publication. The cosmic-ray fluxes inside and near to spacecrafts were also calculated by PHITS, using simplified geometries. The accuracy of the obtained absorbed-dose and dose-equivalent rates was verified by various experimental data measured both inside and outside spacecrafts. The calculations quantitatively show that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents, because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors. These results demonstrate the usefulness of dose conversion coefficients in space dosimetry.

  4. A robust method for determining the absorbed dose to water in a phantom for low-energy photon radiation

    NASA Astrophysics Data System (ADS)

    Schneider, T.

    2011-06-01

    The application of more and more low-energy photon radiation in brachytherapy—either in the form of low-dose-rate radioactive seeds such as Pd-103 or I-125 or in the form of miniature x-ray tubes—has induced greater interest in determining the absorbed dose to water in water in this energy range. As it seems to be hardly feasible to measure the absorbed dose with calorimetric methods in this low energy range, ionometric methods are the preferred choice. However, the determination of the absorbed dose to water in water by ionometric methods is difficult in this energy range. With decreasing energy, the relative uncertainty of the photon cross sections increases and as the mass energy transfer coefficients show a steep gradient, the spectra of the radiation field must be known precisely. In this work two ionometric methods to determine the absorbed dose to water are evaluated with respect to their sensitivity to the uncertainties of the spectra and of the atomic database. The first is the measurement of the air kerma free in air and the application of an MC-based conversion factor to the absorbed dose to water. The second is the determination of the absorbed dose to water by means of an extrapolation chamber as an integral part of a phantom. In the complementing MC-calculations, two assortments of spectra each of which is based on a separate unfolding procedure were used as well as two kinds of databases: the standard PEGS and the recently implemented NIST database of EGSnrc. Experimental results were obtained by using a parallel-plate graphite extrapolation chamber and a free-air chamber. In the case when the water kerma in a phantom is determined from the measurements of air kerma free in air, differences in the order of 10% were found, according to which the database or the kind of spectrum is used. In contrast to this, for the second method, the differences found were about 0.5%.

  5. Determination of the Absorbed Dose Rate to Water for the 18-mm Helmet of a Gamma Knife

    SciTech Connect

    Chung, Hyun-Tai; Park, Youngho; Hyun, Sangil; Choi, Yongsoo; Kim, Gi Hong; Kim, Dong Gyu; Chun, Kook Jin

    2011-04-01

    Purpose: To measure the absorbed dose rate to water of {sup 60}Co gamma rays of a Gamma Knife Model C using water-filled phantoms (WFP). Methods and Materials: Spherical WFP with an equivalent water depth of 5, 7, 8, and 9 cm were constructed. The dose rates at the center of an 18-mm helmet were measured in an 8-cm WFP (WFP-3) and two plastic phantoms. Two independent measurement systems were used: one was calibrated to an air kerma (Set I) and the other was calibrated to the absorbed dose to water (Set II). The dose rates of WFP-3 and the plastic phantoms were converted to dose rates for an 8-cm water depth using the attenuation coefficient and the equivalent water depths. Results: The dose rate measured at the center of WFP-3 using Set II was 2.2% and 1.0% higher than dose rates measured at the center of the two plastic phantoms. The measured effective attenuation coefficient of Gamma Knife photon beam in WFPs was 0.0621 cm{sup -1}. After attenuation correction, the difference between the dose rate at an 8-cm water depth measured in WFP-3 and dose rates in the plastic phantoms was smaller than the uncertainty of the measurements. Conclusions: Systematic errors related to the characteristics of the phantom materials in the dose rate measurement of a Gamma Knife need to be corrected for. Correction of the dose rate using an equivalent water depth and attenuation provided results that were more consistent.

  6. Absorbed dose measurements for kV-cone beam computed tomography in image-guided radiation therapy

    NASA Astrophysics Data System (ADS)

    Hioki, Kazunari; Araki, Fujio; Ohno, Takeshi; Nakaguchi, Yuji; Tomiyama, Yuuki

    2014-12-01

    In this study, we develope a novel method to directly evaluate an absorbed dose-to-water for kilovoltage-cone beam computed tomography (kV-CBCT) in image-guided radiation therapy (IGRT). Absorbed doses for the kV-CBCT systems of the Varian On-Board Imager (OBI) and the Elekta X-ray Volumetric Imager (XVI) were measured by a Farmer ionization chamber with a 60Co calibration factor. The chamber measurements were performed at the center and four peripheral points in body-type (30 cm diameter and 51 cm length) and head-type (16 cm diameter and 33 cm length) cylindrical water phantoms. The measured ionization was converted to the absorbed dose-to-water by using a 60Co calibration factor and a Monte Carlo (MC)-calculated beam quality conversion factor, kQ, for 60Co to kV-CBCT. The irradiation for OBI and XVI was performed with pelvis and head modes for the body- and the head-type phantoms, respectively. In addition, the dose distributions in the phantom for both kV-CBCT systems were calculated with MC method and were compared with measured values. The MC-calculated doses were calibrated at the center in the water phantom and compared with measured doses at four peripheral points. The measured absorbed doses at the center in the body-type phantom were 1.96 cGy for OBI and 0.83 cGy for XVI. The peripheral doses were 2.36-2.90 cGy for OBI and 0.83-1.06 cGy for XVI. The doses for XVI were lower up to approximately one-third of those for OBI. Similarly, the measured doses at the center in the head-type phantom were 0.48 cGy for OBI and 0.21 cGy for XVI. The peripheral doses were 0.26-0.66 cGy for OBI and 0.16-0.30 cGy for XVI. The calculated peripheral doses agreed within 3% in the pelvis mode and within 4% in the head mode with measured doses for both kV-CBCT systems. In addition, the absorbed dose determined in this study was approximately 4% lower than that in TG-61 but the absorbed dose by both methods was in agreement within their combined

  7. Estimating thyroid dose in pediatric CT exams from surface dose measurement

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  8. Estimation of food consumption. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Callaway, J.M. Jr.

    1992-04-01

    The research reported in this document was conducted as a part of the Hanford Environmental Dose Reconstruction (HEDR) Project. The objective of the HEDR Project is to estimate the radiation doses that people could have received from operations at the Hanford Site. Information required to estimate these doses includes estimates of the amounts of potentially contaminated foods that individuals in the region consumed during the study period. In that general framework, the objective of the Food Consumption Task was to develop a capability to provide information about the parameters of the distribution(s) of daily food consumption for representative groups in the population for selected years during the study period. This report describes the methods and data used to estimate food consumption and presents the results developed for Phase I of the HEDR Project.

  9. Spreadsheet calculations of absorbed dose to water for photons and electrons according to established dosimetry protocols.

    PubMed

    Cederbaum, M; Kuten, A

    1999-01-01

    The calculation of absorbed dose to water according to a Code of Practice demands a strict adherence to the rules and data of the protocol. To ease the calculations and to avoid computational and methodological errors, we have developed a number of spreadsheets to perform the calculations in accordance with an established dosimetry protocol-in our case those of the International Atomic Energy Agency (IAEA) and the Institution of Physics and Engineering in Medicine and Biology (IPEMB). The spreadsheets are implemented as Microsoft Excel V5.0 worksheets. Only a limited selection of dosimetry equipment is used for calibration, which is performed according to only one of the methods allowed by the protocol. This voluntary limitation of equipment and methods is reflected in a spreadsheet that is beam-specific, compact, focused, and very practical. There are four main spreadsheets: high-energy photons (IAEA), high-energy electrons (IAEA), medium energy X rays (IPEMB), and low-energy X rays (IPEMB). The sheets allow the input of setup and measured data, but tabulated data and formulas are protected. Parameter values are copied from the protocols, and the relevant value is found by linear interpolation. Once the spreadsheets are drawn up correctly and thoroughly checked, protocol calculations are performed easily and accurately. The spreadsheets presented are tailored to suit our specific needs but can easily be modified to conform to the practices of any other institution. They are not intended as "cookbooks" but need to be filled in by a radiation physicist with the input data checked by a second professional. The same method is also used for calculating the Reference Air Kerma Rate of brachytherapy sources.

  10. Dose-response curve estimation: a semiparametric mixture approach.

    PubMed

    Yuan, Ying; Yin, Guosheng

    2011-12-01

    In the estimation of a dose-response curve, parametric models are straightforward and efficient but subject to model misspecifications; nonparametric methods are robust but less efficient. As a compromise, we propose a semiparametric approach that combines the advantages of parametric and nonparametric curve estimates. In a mixture form, our estimator takes a weighted average of the parametric and nonparametric curve estimates, in which a higher weight is assigned to the estimate with a better model fit. When the parametric model assumption holds, the semiparametric curve estimate converges to the parametric estimate and thus achieves high efficiency; when the parametric model is misspecified, the semiparametric estimate converges to the nonparametric estimate and remains consistent. We also consider an adaptive weighting scheme to allow the weight to vary according to the local fit of the models. We conduct extensive simulation studies to investigate the performance of the proposed methods and illustrate them with two real examples.

  11. Applicability of Fluorescence and Absorbance Spectroscopy to Estimate Organic Pollution in Rivers.

    PubMed

    Knapik, Heloise Garcia; Fernandes, Cristovão Vicente Scapulatempo; de Azevedo, Júlio Cesar Rodrigues; do Amaral Porto, Monica Ferreira

    2014-12-01

    This article explores the applicability of fluorescence and absorbance spectroscopy for estimating organic pollution in polluted rivers. The relationship between absorbance, fluorescence intensity, dissolved organic carbon, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and other water quality parameters were used to characterize and identify the origin and the spatial variability of the organic pollution in a highly polluted watershed. Analyses were performed for the Iguassu River, located in southern Brazil, with area about 2,700 km(2) and ∼3 million inhabitants. Samples were collect at six monitoring sites covering 107 km of the main river. BOD, COD, nitrogen, and phosphorus concentration indicates a high input of sewage to the river. Specific absorbance at 254 and 285 nm (SUVA254 and A285/COD) did not show significant variation between sites monitored, indicating the presence of both dissolved compounds found in domestic effluents and humic and fulvic compounds derived from allochthonous organic matter. Correlations between BOD and tryptophan-like fluorescence peak (peak T2, r=0.7560, and peak T1, r=0.6949) and tyrosine-like fluorescence peak (peak B, r=0.7321) indicated the presence of labile organic matter and thus confirmed the presence of sewage in the river. Results showed that fluorescence and absorbance spectroscopy provide useful information on pollution in rivers from critical watersheds and together are a robust method that is simpler and more rapid than traditional methods employed by regulatory agencies.

  12. Development of a water calorimetry-based standard for absorbed dose to water in HDR {sup 192}Ir brachytherapy

    SciTech Connect

    Sarfehnia, Arman; Seuntjens, Jan

    2010-04-15

    Purpose: The aim of this article is to develop and evaluate a primary standard for HDR {sup 192}Ir brachytherapy based on 4 deg. C stagnant water calorimetry. Methods: The absolute absorbed dose to water was directly measured for several different Nucletron microSelectron {sup 192}Ir sources of air kerma strength ranging between 21 000 and 38 000 U and for source-to-detector separations ranging between 25 and 70 mm. The COMSOL MULTIPHYSICS software was used to accurately calculate the heat transport in a detailed model geometry. Through a coupling of the ''conduction and convection'' module with the ''Navier-Stokes incompressible fluid'' module in the software, both the conductive and convective effects were modeled. Results: A detailed uncertainty analysis resulted in an overall uncertainty in the absorbed dose of 1.90%(1{sigma}). However, this includes a 1.5% uncertainty associated with a nonlinear predrift correction which can be substantially reduced if sufficient time is provided for the system to come to a new equilibrium in between successive calorimetric runs, an opportunity not available to the authors in their clinical setting due to time constraints on the machine. An average normalized dose rate of 361{+-}7 {mu}Gy/(h U) at a source-to-detector separation of 55 mm was measured for the microSelectron {sup 192}Ir source based on water calorimetry. The measured absorbed dose per air kerma strength agreed to better than 0.8%(1{sigma}) with independent ionization chamber and EBT-1 Gafchromic film reference dosimetry as well as with the currently accepted AAPM TG-43 protocol measurements. Conclusions: This work paves the way toward a primary absorbed dose to water standard in {sup 192}Ir brachytherapy.

  13. Radiation dose estimates for copper-64 citrate in man

    SciTech Connect

    Crook, J.E.; Carlton, J.E.; Stabin, M.; Watson, E.

    1985-01-01

    Tumor imaging agents suitable for use with positron emission tomographs are constantly sought. We have performed studies with animal-tumor-bearing models that have demonstrated the rapid uptake of copper-64. The radiation dose estimates for man indicate that the intravenous administration of 7.0 mCi would result in radiation doses to the kidney of 9.8 to 10.5 rads with other organs receiving substantially less radiation. 5 refs., 3 tabs.

  14. 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.

  15. Traversal of cells by radiation and absorbed fraction estimates for electrons and alpha particles

    SciTech Connect

    Eckerman, K.F.; Ryman, J.C.; Taner, A.C.; Kerr, G.D.

    1985-01-01

    Consideration of the pathlength which radiation traverses in a cell is central to algorithms for estimating energy deposition on a cellular level. Distinct pathlength distributions occur for radionuclides: (1) uniformly distributed in space about the cell (referred to as -randomness); (2) uniformly distributed on the surface of the cell (S-randomness); and (3) uniformly distributed within the cell volume (I-randomness). For a spherical cell of diameter d, the mean pathlengths are 2/3d, 1/2d, and 3/4d, respectively, for these distributions. Algorithms for simulating the path of radiation through a cell are presented and the absorbed fraction in the cell and its nucleus are tabulated for low energy electrons and alpha particles emitted on the surface of spherical cells. The algorithms and absorbed fraction data should be of interest to those concerned with the dosimetry of radionuclide-labeled monoclonal antibodies. 8 refs., 3 figs., 2 tabs.

  16. Estimate of doses to the fetus during commercial flights.

    PubMed

    Chen, Jing; Mares, Vladimir

    2008-10-01

    This study assesses the radiation exposure from cosmic rays to fetuses of pregnant aircrew and air travelers. Combining the particle fluence spectra of various cosmic radiations at aircraft altitudes with the fetal fluence-to-dose conversion coefficients calculated for different cosmic ray radiations, the doses to the fetal body were estimated for three prenatal ages. From the five major particle types present during commercial flights, neutrons contribute about 54% of the total fetal dose, followed by protons 22%, photons 11%, electrons 7%, and muons 6%. The results indicate that the dose to the fetus can exceed a recommended fetal dose limit of 1 mSv after 10 round trips on commercial flights between Toronto and Frankfurt.

  17. Maximum likelihood estimation for cytogenetic dose-response curves

    SciTech Connect

    Frome, E.L.; DuFrain, R.J.

    1986-03-01

    In vitro dose-response curves are used to describe the relation between chromosome aberrations and radiation dose for human lymphocytes. The lymphocytes are exposed to low-LET radiation, and the resulting dicentric chromosome aberrations follow the Poisson distribution. The expected yield depends on both the magnitude and the temporal distribution of the dose. A general dose-response model that describes this relation has been presented by Kellerer and Rossi (1972, Current Topics on Radiation Research Quarterly 8, 85-158; 1978, Radiation Research 75, 471-488) using the theory of dual radiation action. Two special cases of practical interest are split-dose and continuous exposure experiments, and the resulting dose-time-response models are intrinsically nonlinear in the parameters. A general-purpose maximum likelihood estimation procedure is described, and estimation for the nonlinear models is illustrated with numerical examples from both experimental designs. Poisson regression analysis is used for estimation, hypothesis testing, and regression diagnostics. Results are discussed in the context of exposure assessment procedures for both acute and chronic human radiation exposure.

  18. Comparison of various techniques for the exact determination of absorbed dose in heavy ion fields using passive detectors

    NASA Astrophysics Data System (ADS)

    Berger, T.; Reitz, G.; Hajek, M.; Vana, N.

    Passive thermoluminescent detectors (TLDs) are commonly applied for the determination of absorbed dose in routine radiation protection. The usage of TLDs in heavy ion fields, e.g. for treatment planing in radiotherapy or in space dosimetry, requires the detailed knowledge of the efficiency of these detectors to the ion under study in dependence on the LET of the ion. This is due to the fact, that the detection efficiency of TLDs changes with increasing LET. This would lead - if the changing efficiency of the TL- material is not taken into account - to a measured deviation of the absorbed dose. In the framework of the ICCHIBAN project - which was started as an intercomparison of passive and active detector systems used for dose determination in space - "Blind" exposures were carried out. No information about dose and ion species was given for the investigators. Three different methods were used for the efficiency correction of TLDs after the BLIND exposures. The first method used the different LET efficiency of the TL-materials LiF: Mg, Ti and LiF:Mg, Cu,P to determine the LET and based on this value the efficiency of the LiF: Mg, Ti dosemeters. The second method used the high temperature emissions in LiF: Mg, Ti for the efficiency correction. The third method applied used a combination of TLDs and CR-39 track etch detectors to determine the total absorbed dose during the BLIND exposures. The paper will discuss the threee methods, and focus on the applicability for the usage of these methods for dose determination and recalculation in space dosimetry.

  19. Comparison of various techniques for the exact determination of absorbed dose in heavy ion fields using passive detectors

    NASA Astrophysics Data System (ADS)

    Berger, T.; Reitz, G.; Hajek, M.; Vana, N.

    Passive thermoluminescent detectors (TLDs) are commonly applied for the determination of absorbed dose in routine radiation protection. The usage of TLDs in heavy ion fields, e.g., in space dosimetry or for treatment planing in radiotherapy, requires the detailed knowledge of the efficiency of these detectors to the ion under study in dependence on the LET of the ion. This is due to the fact, that the detection efficiency of TLDs changes with increasing LET. If the changing efficiency of the TL-material is not taken into account, this would lead to a deviation of the measured absorbed dose. In the framework of the ICCHIBAN project - which was started as an intercomparison of passive and active detector systems used for dose determination in space - "BLIND" exposures were carried out. No information about dose and ion species was given to the investigators. Three different methods were used for the efficiency correction of TLDs after the BLIND exposures. The first method used the different LET efficiency of the TL-materials LiF:Mg, Ti and LiF:Mg, Cu, P to determine the LET and from this LET the efficiency of the LiF:Mg, Ti dosemeters. The second method used the high temperature emissions in LiF:Mg, Ti for the efficiency correction. The third method used a combination of TLDs and CR-39 track etch detectors to determine the total absorbed dose during the BLIND exposures. The paper will discuss the three methods, and focus on their applicability to precise dose determination and recalculation in space dosimetry.

  20. Analytic estimates of secondary neutron dose in proton therapy.

    PubMed

    Anferov, V

    2010-12-21

    Proton beam losses in various components of a treatment nozzle generate secondary neutrons, which bring unwanted out of field dose during treatments. The purpose of this study was to develop an analytic method for estimating neutron dose to a distant organ at risk during proton therapy. Based on radiation shielding calculation methods proposed by Sullivan, we developed an analytical model for converting the proton beam losses in the nozzle components and in the treatment volume into the secondary neutron dose at a point of interest. Using the MCNPx Monte Carlo code, we benchmarked the neutron dose rates generated by the proton beam stopped at various media. The Monte Carlo calculations confirmed the validity of the analytical model for simple beam stop geometry. The analytical model was then applied to neutron dose equivalent measurements performed on double scattering and uniform scanning nozzles at the Midwest Proton Radiotherapy Institute (MPRI). Good agreement was obtained between the model predictions and the data measured at MPRI. This work provides a method for estimating analytically the neutron dose equivalent to a distant organ at risk. This method can be used as a tool for optimizing dose delivery techniques in proton therapy.

  1. Patient-specific dose estimation for pediatric chest CT

    SciTech Connect

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

    2008-12-15

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

  2. Assessment of breast absorbed doses during thoracic computed tomography scan to evaluate the effectiveness of bismuth shielding.

    PubMed

    Alonso, Thessa C; Mourão, Arnaldo P; Santana, Priscila C; da Silva, Teógenes A

    2016-11-01

    During a lung computed tomography (CT) examination, breast and nearby radiosensitive organs are unnecessarily irradiated because they are in the path of the primary beam. The purpose of this paper is to determine the absorbed dose in breast and nearby organs for unshielded and shielded exposures with bismuth. The experiment was done with a female anthropomorphic phantom undergoing a typical thoracic CT scan, with TLD-100 thermoluminescent detectors insert at breast, lung and thyroid positions. Results showed that dose reduction due to bismuth shielding was approximately 30% and 50% for breast and thyroid, respectively; however, the influence of the bismuth on the image quality needs to be considered.

  3. Dose estimates in a loss of lead shielding truck accident.

    SciTech Connect

    Dennis, Matthew L.; Osborn, Douglas M.; Weiner, Ruth F.; Heames, Terence John

    2009-08-01

    The radiological transportation risk & consequence program, RADTRAN, has recently added an updated loss of lead shielding (LOS) model to it most recent version, RADTRAN 6.0. The LOS model was used to determine dose estimates to first-responders during a spent nuclear fuel transportation accident. Results varied according to the following: type of accident scenario, percent of lead slump, distance to shipment, and time spent in the area. This document presents a method of creating dose estimates for first-responders using RADTRAN with potential accident scenarios. This may be of particular interest in the event of high speed accidents or fires involving cask punctures.

  4. Mean Absorbed Dose to the Anal-Sphincter Region and Fecal Leakage among Irradiated Prostate Cancer Survivors

    SciTech Connect

    Alsadius, David; Hedelin, Maria; Lundstedt, Dan; Pettersson, Niclas; Wilderaeng, Ulrica; Steineck, Gunnar

    2012-10-01

    Purpose: To supplement previous findings that the absorbed dose of ionizing radiation to the anal sphincter or lower rectum affects the occurrence of fecal leakage among irradiated prostate-cancer survivors. We also wanted to determine whether anatomically defining the anal-sphincter region as the organ at risk could increase the degree of evidence underlying clinical guidelines for restriction doses to eliminate this excess risk. Methods and Materials: We identified 985 men irradiated for prostate cancer between 1993 and 2006. In 2008, we assessed long-term gastrointestinal symptoms among these men using a study-specific questionnaire. We restrict the analysis to the 414 men who had been treated with external beam radiation therapy only (no brachytherapy) to a total dose of 70 Gy in 2-Gy daily fractions to the prostate or postoperative prostatic region. On reconstructed original radiation therapy dose plans, we delineated the anal-sphincter region as an organ at risk. Results: We found that the prevalence of long-term fecal leakage at least once per month was strongly correlated with the mean dose to the anal-sphincter region. Examining different dose intervals, we found a large increase at 40 Gy; {>=}40 Gy compared with <40 Gy gave a prevalence ratio of 3.8 (95% confidence interval 1.6-8.6). Conclusions: This long-term study shows that mean absorbed dose to the anal-sphincter region is associated with the occurrence of long-term fecal leakage among irradiated prostate-cancer survivors; delineating the anal-sphincter region separately from the rectum and applying a restriction of a mean dose <40 Gy will, according to our data, reduce the risk considerably.

  5. Application of airborne gamma spectrometric survey data to estimating terrestrial gamma-ray dose rates: an example in California.

    PubMed

    Wollenberg, H A; Revzan, K L; Smith, A R

    1994-01-01

    We examined the applicability of radioelement data from the National Aerial Radiometric Reconnaissance, an element of the National Uranium Resource Evaluation, to estimate terrestrial gamma-ray absorbed dose rates, by comparing dose rates calculated from aeroradiometric surveys of uranium, thorium, and potassium concentrations with dose rates calculated from a radiogeologic data base and the distribution of lithologies in California. Gamma-ray dose rates increase generally from north to south following lithological trends, with low values of 25-30 nGy h-1 in the northernmost 1 x 2 degrees quadrangles between 41 and 42 degrees N to high values of 75-100 nGy h-1 in southeastern California. Lithologic-based estimates of mean dose rates in the quadrangles generally match those from aeroradiometric data, with statewide means of 63 and 60 nGy h-1, respectively. These are intermediate between a population-weighted global average of 51 nGy h-1 reported in 1982 by UNSCEAR and a weighted continental average of 70 nGy h-1, based on the global distribution of rock types. The concurrence of lithologically and aeroradiometrically determined dose rates in California, with its varied geology and topography encompassing settings representative of the continents, indicates that the National Aerial Radiometric Reconnaissance data are applicable to estimates of terrestrial absorbed dose rates from natural gamma emitters.

  6. SU-E-T-30: Absorbed Doses Determined by Texture Analysis of Gafchromic EBT3 Films Using Scanning Electron Microscopy: A Feasibility Study

    SciTech Connect

    Park, S; Kim, H; Ye, S

    2014-06-01

    Purpose: The texture analysis method is useful to estimate structural features of images as color, size, and shape. The study aims to determine a dose-response curve by texture analysis of Gafchromic EBT3 film images using scanning electron microscopy (SEM). Methods: The uncoated Gafchromic EBT3 films were prepared to directly scan over the active surface layer of EBT3 film using SEM. The EBT3 films were exposed at a dose range of 0 to 10 Gy using a 6 MV photon beam. The exposed film samples were SEM-scanned at 100X, 1000X, and 3000X magnifications. The four texture features (Homogeneity, Correlation, Contrast, and Energy) were calculated based on the gray level co-occurrence matrix (GLCM) derived from the SEM images at each dose. To validate a correlation between delivered doses and texture features, an R-squared value in linear regression was tested. Results: The results showed that the Correlation index was more suitable as dose indices than the other three texture features due to higher linearity and sensitivity of the dose response curves. Further the Correlation index of 3000X magnified SEM images with 9 pixel offsets had an R-squared value of 0.964. The differences between the delivered doses and the doses measured by this method were 0.9, 1.2, 0.2, and 0.2 Gy at 5, 10, 15, and 20 Gy, respectively. Conclusion: It seems to be feasible to convert micro-scale structural features of {sub χ}t{sub χχχ}he EBT3 films to absorbed doses using the texture analysis method.

  7. [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.

  8. Depth dependence of absorbed dose, dose equivalent and linear energy transfer spectra of galactic and trapped particles in polyethylene and comparison with calculations of models

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Cucinotta, F. A.; Wilson, J. W. (Principal Investigator)

    1998-01-01

    A matched set of five tissue-equivalent proportional counters (TEPCs), embedded at the centers of 0 (bare), 3, 5, 8 and 12-inch-diameter polyethylene spheres, were flown on the Shuttle flight STS-81 (inclination 51.65 degrees, altitude approximately 400 km). The data obtained were separated into contributions from trapped protons and galactic cosmic radiation (GCR). From the measured linear energy transfer (LET) spectra, the absorbed dose and dose-equivalent rates were calculated. The results were compared to calculations made with the radiation transport model HZETRN/NUCFRG2, using the GCR free-space spectra, orbit-averaged geomagnetic transmission function and Shuttle shielding distributions. The comparison shows that the model fits the dose rates to a root mean square (rms) error of 5%, and dose-equivalent rates to an rms error of 10%. Fairly good agreement between the LET spectra was found; however, differences are seen at both low and high LET. These differences can be understood as due to the combined effects of chord-length variation and detector response function. These results rule out a number of radiation transport/nuclear fragmentation models. Similar comparisons of trapped-proton dose rates were made between calculations made with the proton transport model BRYNTRN using the AP-8 MIN trapped-proton model and Shuttle shielding distributions. The predictions of absorbed dose and dose-equivalent rates are fairly good. However, the prediction of the LET spectra below approximately 30 keV/microm shows the need to improve the AP-8 model. These results have strong implications for shielding requirements for an interplanetary manned mission.

  9. Developing milk industry estimates for dose reconstruction projects

    SciTech Connect

    Beck, D.M.; Darwin, R.F. )

    1991-01-01

    One of the most important contributors to radiation doses from hanford during the 1944-1947 period was radioactive iodine. Consumption of milk from cows that ate vegetation contaminated with iodine is likely the dominant pathway of human exposure. To estimate the doses people could have received from this pathway, it is necessary to reconstruct the amount of milk consumed by people living near Hanford, the source of the milk, and the type of feed that the milk cows ate. This task is challenging because the dairy industry has undergone radical changes since the end of World War 2, and records that document the impact of these changes on the study area are scarce. Similar problems are faced by researchers on most dose reconstruction efforts. The purpose of this work is to document and evaluate the methods used on the Hanford Environmental Dose Reconstruction (HEDR) Project to reconstruct the milk industry and to present preliminary results.

  10. Estimation of the Warfarin Dose with Clinical and Pharmacogenetic Data

    PubMed Central

    2009-01-01

    BACKGROUND Genetic variability among patients plays an important role in determining the dose of warfarin that should be used when oral anticoagulation is initiated, but practical methods of using genetic information have not been evaluated in a diverse and large population. We developed and used an algorithm for estimating the appropriate warfarin dose that is based on both clinical and genetic data from a broad population base. METHODS Clinical and genetic data from 4043 patients were used to create a dose algorithm that was based on clinical variables only and an algorithm in which genetic information was added to the clinical variables. In a validation cohort of 1009 subjects, we evaluated the potential clinical value of each algorithm by calculating the percentage of patients whose predicted dose of warfarin was within 20% of the actual stable therapeutic dose; we also evaluated other clinically relevant indicators. RESULTS In the validation cohort, the pharmacogenetic algorithm accurately identified larger proportions of patients who required 21 mg of warfarin or less per week and of those who required 49 mg or more per week to achieve the target international normalized ratio than did the clinical algorithm (49.4% vs. 33.3%, P<0.001, among patients requiring ≤21 mg per week; and 24.8% vs. 7.2%, P<0.001, among those requiring ≥49 mg per week). CONCLUSIONS The use of a pharmacogenetic algorithm for estimating the appropriate initial dose of warfarin produces recommendations that are significantly closer to the required stable therapeutic dose than those derived from a clinical algorithm or a fixed-dose approach. The greatest benefits were observed in the 46.2% of the population that required 21 mg or less of warfarin per week or 49 mg or more per week for therapeutic anticoagulation. PMID:19228618

  11. Organ doses for reference pediatric and adolescent patients undergoing computed tomography estimated by Monte Carlo simulation

    SciTech Connect

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.; Bolch, Wesley E.

    2012-04-15

    Purpose: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model. Methods: The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs/tissues normalized to the product of 100 mAs and CTDI{sub vol} (mGy/100 mAs mGy) was established by coupling the CT scanner model with age-dependent reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI{sub vol}- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP). Results: Organ and effective doses were calculated and normalized to 100 mAs and CTDI{sub vol} for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and/or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose

  12. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow

    SciTech Connect

    Ichimaru, M.; Ishimaru, T.; Mikami, M.; Matsunaga, M.

    1982-08-01

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimaged risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure.

  13. Measurement-based estimates of direct radiative effects of absorbing aerosols above clouds

    NASA Astrophysics Data System (ADS)

    Feng, Nan; Christopher, Sundar A.

    2015-07-01

    The elevated layers of absorbing smoke aerosols from western African (e.g., Gabon and Congo) biomass burning activities have been frequently observed above low-level stratocumulus clouds off the African coast, which presents an excellent natural laboratory for studying the effects of aerosols above clouds (AAC) on regional energy balance in tropical and subtropical environments. Using spatially and temporally collocated Moderate Resolution Imaging Spectroradiometer, Ozone Monitoring Instrument (OMI), and Clouds and the Earth's Radiant Energy System data sets, the top-of-atmosphere shortwave aerosol direct shortwave radiative effects (ARE) of absorbing aerosols above low-level water clouds in the southeast Atlantic Ocean was examined in this study. The regional averaged instantaneous ARE has been estimated to be 36.7 ± 20.5 Wm-2 (regional mean ± standard deviation) along with a mean positive OMI Aerosol Index at 1.3 in August 2006 based on multisensors measurements. The highest magnitude of instantaneous ARE can even reach 138.2 Wm-2. We assess that the 660 nm cloud optical depth (COD) values of 8-12 is the critical value above (below) which aerosol absorption (scattering) effect dominates and further produces positive (negative) ARE values. The results further show that ARE values are more sensitive to aerosols above lower COD values than cases for higher COD values. This is among the first studies to provide quantitative estimates of shortwave ARE due to AAC events from an observational perspective.

  14. Study of the spatial distribution of the absorbed dose in blood volumes irradiated using a teletherapy unit

    NASA Astrophysics Data System (ADS)

    Góes, E. G.; Nicolucci, P.; Nali, I. C.; Pelá, C. A.; Bruço, J. L.; Borges, J. C.; Covas, D. T.

    2010-06-01

    Blood irradiation can be performed using a dedicated blood irradiator or a teletherapy unit. A thermal device providing appropriate storage conditions during blood components irradiation with a teletherapy unit has been recently proposed. However, the most appropriated volume of the thermal device was not indicated. The goal of this study was to indicate the most appropriated blood volume for irradiation using a teletherapy unit in order to minimize both the dose heterogeneity in the volume and the blood irradiation time using these equipments. Theoretical and experimental methods were used to study the dose distribution in the blood volume irradiated using a linear accelerator and a cobalt-60 therapy machine. The calculation of absorbed doses in the middle plane of cylindrical acrylic volumes was accomplished by a treatment planning system. Experimentally, we also used cylindrical acrylic phantoms and thermoluminescent dosimeters to confirm the calculated doses. The data obtained were represented by isodose curves. We observed that an irradiation volume should have a height of 28 cm and a diameter of 28 cm and a height of 35 cm and a diameter of 35 cm, when the irradiation is to be performed by a linear accelerator and a cobalt-60 teletherapy unit, respectively. Calculated values of relative doses varied from 93% to 100% in the smaller volume, and from 66% to 100% in the largest one. A difference of 5.0%, approximately, was observed between calculated and experimental data. The size of these volumes permits the irradiation of blood bags in only one bath without compromising the homogeneity of the absorbed dose over the irradiated volume. Thus, these irradiation volumes can be recommend to minimize the irradiation time when a teletherapy unit is used to irradiate blood.

  15. A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources.

    PubMed

    Sliski, Alan; Soares, Christopher; Mitch, Michael G

    2006-01-01

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a (103)Pd source of air-kerma strength 3.4 U (1 U = 1 microGy m(2) h(-1)), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries such as eye applicators for treating macular degeneration.

  16. Influence of DTPA Treatment on Internal Dose Estimates.

    PubMed

    Davesne, Estelle; Blanchardon, Eric; Peleau, Bernadette; Correze, Philippe; Bohand, Sandra; Franck, Didier

    2016-06-01

    In case of internal contamination with plutonium materials, a treatment with diethylene triamine pentaacetic acid (DTPA) can be administered in order to reduce plutonium body burden and consequently avoid some radiation dose. DTPA intravenous injections or inhalation can start almost immediately after intake, in parallel with urinary and fecal bioassay sampling for dosimetric follow-up. However, urine and feces excretion will be significantly enhanced by the DTPA treatment. As internal dose is calculated from bioassay results, the DTPA effect on excretion has to be taken into account. A common method to correct bioassay data is to divide it by a factor representing the excretion enhancement under DTPA treatment by intravenous injection. Its value may be based on a nominal reference or observed after a break in the treatment. The aim of this study was to estimate the influence of this factor on internal dose by comparing the dose estimated using default or upper and lower values of the enhancement factor for 11 contamination cases. The observed upper and lower values of the enhancement factor were 18.7 and 63.0 for plutonium and 24.9 and 28.8 for americium. For americium, a default factor of 25 is proposed. This work demonstrates that the use of a default DTPA enhancement factor allows the determination of the magnitude of the contamination because dose estimated could vary by a factor of 2 depending on the value of the individual DTPA enhancement factor. In case of significant intake, an individual enhancement factor should be determined to obtain a more reliable dose assessment.

  17. Methodology for estimating radiation dose rates to freshwater biota exposed to radionuclides in the environment

    SciTech Connect

    Blaylock, B.G.; Frank, M.L.; O`Neal, B.R.

    1993-08-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

  18. Absorbed dose measurements in dual energy X-ray absorptiometry (DXA).

    PubMed

    Bezakova, E; Collins, P J; Beddoe, A H

    1997-02-01

    In this study a predominantly film dosimetric method was used to measure the effective dose from posteroanterior (PA) lumbar spine and proximal femur scans performed on a Lunar DPX-L machine. Because of the very low dose rate in scanning mode, the depth dose data were determined using a stationary detector configuration. The characteristic curve for the film (Kodak TMAT-H) was obtained and depth dose measurements were made using slabs of "solid water". The film was calibrated using a superficial X-ray unit (calibrated against a standard traceable to a national standard). To assess the change in film response with beam hardening at depth, the film was exposed to calibration beams of different half value layer (HVL). The HVL of the DXA beam was determined for surface and depth doses using aluminium filters and a diamond detector (an energy independent device). All measurements were performed three times. Beam size was measured using film, and the scan areas and times were determined by scanning phantoms. The dose from a scan was calculated using Dsc = DTscAb/Asc, where D = dose rate (stationary), Tsc = scan time, Ab = beam area, and Asc = scan area. Organ doses were determined using an anatomical atlas and ICRP 23 female reference. All film measurements had good precision (coefficient of variation < 4%). There was little variation in film sensitivity with change in HVL (< 1% change for the first three HVLs) and consequently no corrections were applied to the depth dose data. Skin entrance dose was 11.5 microGy. Effective dose in females was 0.19 microSv for the PA lumbar spine. For the proximal femur scan, the effective dose was 0.14 microSv (ovaries included) and 0.023 microSv (ovaries excluded) for pre-menopausal and pos-menopausal women, respectively.

  19. Dose estimates for the heavy concrete ratchet wall configuration

    SciTech Connect

    Knott, M.J.; Moe, H.J.

    1988-09-01

    The recalculation of the estimated doses due to a beam loss at a single point in the storage-ring system indicates that the redesigned shielding geometry, using heavy concrete for the ratchet walls, is generally adequate for the parameters of no local lead shielding and an operating current of 0.1 A. For operation at 0.3 A, additional local lead shielding of 8 cm of lead will assure that all doses outside the ratchet wall shield from a beam loss at a given point will be {lt} 1 mSv.

  20. Dose estimates for the solid waste performance assessment

    SciTech Connect

    Rittman, P.D.

    1994-08-30

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

  1. Estimation of Secondary Neutron Dose during Proton Therapy

    NASA Astrophysics Data System (ADS)

    Urban, Tomas; Klusoň, Jaroslav

    2014-06-01

    During proton radiotherapy, secondary neutrons are produced by nuclear interactions in the material along the beam path, in the treatment nozzle (including the fixed scatterer, range modulator, etc.) and, of course, after entering the patient. The dose equivalent deposited by these neutrons is usually not considered in routine treatment planning. In this study, there has been estimated the neutron dose in patient (in as well as around the target volume) during proton radiotherapy using scattering and scanning techniques. The proton induced neutrons (and photons) have been simulated in the simple geometry of the single scattering and the pencil beam scanning universal nozzles and in geometry of the plastic phantom (made of tissue equivalent material - RW3 - imitate the patient). In simulations of the scattering nozzle, different types of brass collimators have been used as well. Calculated data have been used as an approximation of the radiation field in and around the chosen/potential target volume in the patient (plastic phantom). For the dose equivalent evaluation, fluence-to-dose conversion factors from ICRP report have been employed. The results of calculated dose from neutrons in various distances from the spot for different treatment technique and for different energies of incident protons have been compared and evaluated in the context of the dose deposited in the target volume. This work was supported by RVO: 68407700 and Grant Agency of the CTU in Prague, grant No. SGS12/200/OHK4/3T/14.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2016-04-21

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

  4. The use of high spectral resolution bands for estimating absorbed photosynthetically active radiation (A par)

    NASA Technical Reports Server (NTRS)

    Kim, Moon S.; Daughtry, C. S. T.; Chappelle, E. W.; Mcmurtrey, J. E.; Walthall, C. L.

    1994-01-01

    Most remote sensing estimations of vegetation variables such as Leaf Area Index (LAI), Absorbed Photosynthetically Active Radiation (APAR), and phytomass are made using broad band sensors with a bandwidth of approximately 100 nm. However, high resolution spectrometers are available and have not been fully exploited for the purpose of improving estimates of vegetation variables. A study directed to investigate the use of high spectral resolution spectroscopy for remote sensing estimates of APAR in vegetation canopies in the presence of nonphotosynthetic background materials such as soil and leaf litter is presented. A high spectral resolution method defined as the Chlorophyll Absorption Ratio Index (CARI) was developed for minimizing the effects of nonphotosynthetic materials in the remote estimates of APAR. CARI utilizes three bands at 550, 670, and 700 nm with bandwidth of 10 nm. Simulated canopy reflectance of a range of LAI were generated with the SAIL model using measurements of 42 different soil types as canopy background. CARI obtained from the simulated canopy reflectance was compared with the broad band vegetation indices (Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), and Simple Ratio (SR)). CARI reduced the effect of nonphotosynthetic background materials in the assessment of vegetation canopy APAR more effectively than broad band vegetation indices.

  5. Evaluation of a deterministic grid-based Boltzmann solver (GBBS) for voxel-level absorbed dose calculations in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Mikell, Justin; Cheenu Kappadath, S.; Wareing, Todd; Erwin, William D.; Titt, Uwe; Mourtada, Firas

    2016-06-01

    To evaluate the 3D Grid-based Boltzmann Solver (GBBS) code ATTILA ® for coupled electron and photon transport in the nuclear medicine energy regime for electron (beta, Auger and internal conversion electrons) and photon (gamma, x-ray) sources. Codes rewritten based on ATTILA are used clinically for both high-energy photon teletherapy and 192Ir sealed source brachytherapy; little information exists for using the GBBS to calculate voxel-level absorbed doses in nuclear medicine. We compared DOSXYZnrc Monte Carlo (MC) with published voxel-S-values to establish MC as truth. GBBS was investigated for mono-energetic 1.0, 0.1, and 0.01 MeV electron and photon sources as well as 131I and 90Y radionuclides. We investigated convergence of GBBS by analyzing different meshes ({{M}0},{{M}1},{{M}2} ), energy group structures ({{E}0},{{E}1},{{E}2} ) for each radionuclide component, angular quadrature orders (≤ft. {{S}4},{{S}8},{{S}16}\\right) , and scattering order expansions ({{P}0} -{{P}6} ); higher indices imply finer discretization. We compared GBBS to MC in (1) voxel-S-value geometry for soft tissue, lung, and bone, and (2) a source at the interface between combinations of lung, soft tissue, and bone. Excluding Auger and conversion electrons, MC agreed within  ≈5% of published source voxel absorbed doses. For the finest discretization, most GBBS absorbed doses in the source voxel changed by less than 1% compared to the next finest discretization along each phase space variable indicating sufficient convergence. For the finest discretization, agreement with MC in the source voxel ranged from  -3% to  -20% with larger differences at lower energies (-3% for 1 MeV electron in lung to  -20% for 0.01 MeV photon in bone); similar agreement was found for the interface geometries. Differences between GBBS and MC in the source voxel for 90Y and 131I were  -6%. The GBBS ATTILA was benchmarked against MC in the nuclear medicine regime. GBBS can be a viable

  6. Equivalent normalized total dose estimates in cyberknife radiotherapy dose delivery in prostate cancer hypofractionation regimens.

    PubMed

    Sudahar, H; Kurup, P G G; Murali, V; Mahadev, P; Velmurugan, J

    2012-04-01

    As the α/β value of prostate is very small and lower than the surrounding critical organs, hypofractionated radiotherapy became a vital mode of treatment of prostate cancer. Cyberknife (Accuray Inc., Sunnyvale, CA, USA) treatment for localized prostate cancer is performed in hypofractionated dose regimen alone. Effective dose escalation in the hypofractionated regimen can be estimated if the corresponding conventional 2 Gy per fraction equivalent normalized total dose (NTD) distribution is known. The present study aims to analyze the hypofractionated dose distribution of localized prostate cancer in terms of equivalent NTD. Randomly selected 12 localized prostate cases treated in cyberknife with a dose regimen of 36.25 Gy in 5 fractions were considered. The 2 Gy per fraction equivalent NTDs were calculated using the formula derived from the linear quadratic (LQ) model. Dose distributions were analyzed with the corresponding NTDs. The conformity index for the prescribed target dose of 36.25 Gy equivalent to the NTD dose of 90.63 Gy (α/β = 1.5) or 74.31 Gy (α/β = 3) was ranging between 1.15 and 1.73 with a mean value of 1.32 ± 0.15. The D5% of the target was 111.41 ± 8.66 Gy for α/β = 1.5 and 90.15 ± 6.57 Gy for α/β = 3. Similarly, the D95% was 91.98 ± 3.77 Gy for α/β = 1.5 and 75.35 ± 2.88 Gy for α/β = 3. The mean values of bladder and rectal volume receiving the prescribed dose of 36.25 Gy were 0.83 cm3 and 0.086 cm3, respectively. NTD dose analysis shows an escalated dose distribution within the target for low α/β (1.5 Gy) with reasonable sparing of organs at risk. However, the higher α/β of prostate (3 Gy) is not encouraging the fact of dose escalation in cyberknife hypofractionated dose regimen of localized prostate cancer.

  7. Imaging of Absorbed Dose in Radiotherapy by a Polymer Gel Dosimeter

    NASA Astrophysics Data System (ADS)

    Vanossi, E.; Gambarini, G.; Carrara, M.; Mariani, M.; Negri, A.

    2008-06-01

    Optical imaging of polymer gel dosimeters in form of layers was investigated to enquire their reliability for in-phantom dose measurements in photon or thermal neutron fields. The obtained dose measurements were compared with those achieved by means of Fricke gel dosimeters. Reliability of Fricke gel dosimeters was confirmed, whereas it has been shown that a conspicuous improvement of the adopted polymer gel dosimeters is necessary.

  8. 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

  9. Estimating solar radiation absorbed by live phytoplankton from satellite ocean-color data

    NASA Astrophysics Data System (ADS)

    Frouin, Robert J.; Ruddorff, Natalia M.; Kampel, Milton

    2014-11-01

    Primary production, PP, or the quantity of organic matter synthesized by phytoplankton per unit of surface and time, depends on the photo-synthetically available radiation absorbed by live phytoplankton, APAR. Computing APAR requires knowledge of the absorption coefficient of live phytoplankton and the total absorption coefficient, quantities that are difficult to retrieve accurately from satellite ocean-color data. In the proposed approach, APAR is estimated directly from a linear combination of marine reflectance in the PAR spectral range. Feasibility is demonstrated theoretically from simulations using a marine reflectance model, and experimentally using data collected at 19 biooptical stations during the February-March 2011 R/V Melville oceanographic cruise in the Southern Atlantic and Southeastern Pacific. Improvements in APAR accuracy are quantified in comparisons with estimates obtained from absorption coefficients or chlorophyll concentration determined from marine reflectance via standard satellite algorithms. The linear combination of marine reflectance is fairly robust to atmospheric correction errors. Due to the linear nature of the algorithm, their impact may be further reduced when using space- or time-averaged reflectance. The methodology is applied to actual MODIS imagery over the Southern Atlantic, and variability in the resulting APAR field is analyzed. The study suggests that determining APAR directly from marine reflectance has the potential to improve PP estimates from space.

  10. Current activities in the ICRP concerning estimation of radiation doses to patients from radiopharmaceuticals for diagnostic use

    NASA Astrophysics Data System (ADS)

    Mattsson, S.; Johansson, L.; Leide-Svegborn, S.; Liniecki, J.; Nosske, D.; Riklund, K.; Stabin, M.; Taylor, D.

    2011-09-01

    A Task Group within the ICRP Committees 2 and 3 is continuously working to improve absorbed dose estimates to patients investigated with radiopharmaceuticals. The work deals with reviews of the literature, initiation of new or complementary studies of the biokinetics of a compound and dose estimates. Absorbed dose calculations for organs and tissues have up to now been carried out using the MIRD formalism. There is still a lack of necessary biokinetic data from measurements in humans. More time series obtained by nuclear medicine imaging techniques such as whole-body planar gamma-camera imaging, SPECT or PET are highly desirable for this purpose. In 2008, a new addendum to ICRP Publication 53 was published under the name of ICRP Publication 106 containing biokinetic data and absorbed dose information to organs and tissues of patients of various ages for radiopharmaceuticals in common use. That report also covers a number of generic models and realistic maximum models covering other large groups of substances (e.g. "123I-brain receptor substances"). Together with ICRP Publication 80, most radiopharmaceuticals in clinical use at the time of publication were covered except the radioiodine labeled compounds for which the ICRP dose estimates are still found in Publication 53. There is an increasing use of new radiopharmaceuticals, especially PET-tracers and the TG has recently finished its work with biokinetic and dosimetric data for 18F-FET, 18F-FLT and 18F-choline. The work continues now with new data for 11C-raclopride, 11C-PiB and 123I-ioflupan as well as re-evaluation of published data for 82Rb-chloride, 18F-fluoride and radioiodide. This paper summarises published ICRP-information on dose to patients from radiopharmaceuticals and gives some preliminary data for substances under review.

  11. Calculation of the absorbed dose for the overexposed patients at the JCO criticality accident in Tokai-mura.

    PubMed

    Ishigure, N; Endo, A; Yamaguchi, Y; Kawachi, K

    2001-09-01

    The doses for the overexposed patients were estimated by the measurement result of specific activity of 24Na in blood. The present method is almost based on documents of the International Atomic Energy Agency (IAEA) and the Oak Ridge National Laboratory. The neutron energy spectrum obtained using the ANISN code (Multigroup One-Dimensional Discrete Ordinates Transport Code System with Anisotropic Scattering) was assumed. The values in ICRP Publication 74 were applied for the doses in each organ per unit neutron fluence. Gamma-ray dose was indirectly estimated based on (a) the result of environmental monitoring around the accident site and (b) a graph in IAEA manual, which gives the kerma ratio of neutrons and gamma-rays as a function of the critical volume or the atomic ratio of hydrogen to 235U. The estimated neutron doses were 5.4 Gy for patient A. 2.9 Gy for patient B and 0.81 Gy for patient C. The estimated gamma-ray doses were 8.5 or 13 Gy for patient A, 4.5 or 6.9 Gy for patient B, and 1.3 or 2.0 Gy for patient C.

  12. Evaluation of the breast absorbed dose distribution using the Fricke Xylenol Gel

    NASA Astrophysics Data System (ADS)

    Czelusniak, C.; Del Lama, L. S.; Moreira, M. V.; De Almeida, A.

    2010-11-01

    During a breast cancer radiotherapy treatment, several issues have to be taken into account, among them, hot spots, gradient of doses delivered over the breast, as well as in the lungs and the heart. The present work aims to apply the Fricke Xylenol Gel (FXG) dosimeter in the study of these issues, using a CCD camera to analyse the dose deposited distribution. Thus, the CCD was used to capture the images of different cuvettes that were filled with FXG and irradiated considering analogous setups employed in breast cancer radiotherapy treatments. Thereafter, these pictures where processed in a MatLab routine and the spatial dose distributions could be evaluated. These distributions were compared with the ones that were obtained from dedicated treatment planning's softwares. According to the results obtained, the FXG, allied with the CCD system, has shown to be a complementary tool in dosimetry, helping to prevent possible complications during breast cancer treatments.

  13. Methodology for Estimating Radiation Dose Rates to Freshwater Biota Exposed to Radionuclides in the Environment

    SciTech Connect

    Blaylock, B.G.

    1993-01-01

    The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiation dose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiation doses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiation dose rate to biota to the U.S. Department of Energy's (DOE's) recommended dose rate limit of 0.4 mGy h{sup -1} (1 rad d{sup -1}). A dose rate no greater than 0.4 mGy h{sup -1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE's recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). The literature identifies the developing eggs and young of some species of teleost fish as the most radiosensitive organisms. DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiation dose rate of 0.1 mGy h{sup -1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be

  14. An estimation of radiation doses to benthic invertebrates from sediments collected near a Canadian uranium mine.

    PubMed

    Thomas, P; Liber, K

    2001-10-01

    A new method is described for calculating radiation doses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiation doses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects.

  15. Space radiation dose estimates on the surface of Mars.

    PubMed

    Simonsen, L C; Nealy, J E; Townsend, L W; Wilson, J W

    1990-01-01

    A future goal of the U.S. space program is a commitment to the manned exploration and habitation of Mars. An important consideration of such missions is the exposure of crew members to the damaging effects of ionizing radiation from high-energy galactic cosmic ray fluxes and solar proton flares. The crew will encounter the most harmful radiation environment in transit to Mars from which they must be adequately protected. However, once on the planet's surface, the Martian environment should provide a significant amount of protection from free-space radiative fluxes. In current Mars scenario descriptions, the crew flight time to Mars is estimated to be anywhere from 7 months to over a year each way, with stay times on the surface ranging from 20 days to 2 years. To maintain dose levels below established astronaut limits, dose estimates need to be determined for the entire mission length. With extended crew durations on the surface anticipated, the characterization of the Mars radiation environment is important in assessing all radiation protection requirements. This synopsis focuses on the probable doses incurred by surface inhabitants from the transport of galactic cosmic rays and solar protons through the Mars atmosphere.

  16. Contrast-enhanced radiotherapy: feasibility and characteristics of the physical absorbed dose distribution for deep-seated tumors

    NASA Astrophysics Data System (ADS)

    Garnica-Garza, H. M.

    2009-09-01

    Radiotherapy using kilovoltage x-rays in conjunction with contrast agents incorporated into the tumor, gold nanoparticles in particular, could represent a potential alternative to current techniques based on high-energy linear accelerators. In this paper, using the voxelized Zubal phantom in conjunction with the Monte Carlo code PENELOPE to model a prostate cancer treatment, it is shown that in combination with a 360° arc delivery technique, tumoricidal doses of radiation can be delivered to deep-seated tumors while still providing acceptable doses to the skin and other organs at risk for gold concentrations in the tumor within the range of 7-10 mg-Au per gram of tissue. Under these conditions and using a x-ray beam with 90% of the fluence within the range of 80-200 keV, a 72 Gy physical absorbed dose to the prostate can be delivered, while keeping the rectal wall, bladder, skin and femoral heads below 65 Gy, 55 Gy, 40 Gy and 30 Gy, respectively. However, it is also shown that non-uniformities in the contrast agent concentration lead to a severe degradation of the dose distribution and that, therefore, techniques to locally quantify the presence of the contrast agent would be necessary in order to determine the incident x-ray fluence that best reproduces the dosimetry obtained under conditions of uniform contrast agent distribution.

  17. A practical method for skin dose estimation in interventional cardiology based on fluorographic DICOM information.

    PubMed

    Matthews, Lucy; Dixon, Matthew; Rowles, Nick; Stevens, Greg

    2016-03-01

    A practical method for skin dose estimation for interventional cardiology patients has been developed to inform pre-procedure planning and post-procedure patient management. Absorbed dose to the patient skin for certain interventional radiology procedures can exceed thresholds for deterministic skin injury, requiring documentation within the patient notes and appropriate patient follow-up. The primary objective was to reduce uncertainty associated with current methods, particularly surrounding field overlap. This was achieved by considering rectangular field geometry incident on a spherical patient model in a polar coordinate system. The angular size of each field was quantified at surface of the sphere, i.e. the skin surface. Computer-assisted design software enabled the modelling of a sufficient dataset that was subsequently validated with radiochromic film. Modelled overlap was found to agree with overlap measured using film to within 2.2° ± 2.0°, showing that the overall error associated with the model was < 1 %. Mathematical comparison against exposure data extracted from procedural Digital Imaging and Communication in Medicine files was used to generate a graphical skin dose map, demonstrating the dose distribution over a sphere centred at the interventional reference point. Dosimetric accuracy of the software was measured as between 3.5 and 17 % for different variables.

  18. MONTE CARLO STUDY OF THE CARDIAC ABSORBED DOSE DURING X-RAY EXAMINATION OF AN ADULT PATIENT.

    PubMed

    Kadri, O; Manai, K; Alfuraih, A

    2016-12-01

    The computational voxel phantom 'High-Definition Reference Korean-Man (HDRK-Man)' was implemented into the Monte Carlo transport toolkit Geant4. The voxel model, adjusted to the Reference Korean Man, is 171 cm in height and 68 kg in weight and composed of ∼30 million voxels whose size is 1.981 × 1.981 × 2.0854 mm(3) The Geant4 code is then utilised to compute the dose conversion coefficients (DCCs) expressed in absorbed dose per air kerma free in air for >30 tissues and organs, including almost all organs required in the new recommendation of the ICRP 103, due to a broad parallel beam of monoenergetic photons impinging in antero-postero direction with energy ranging from 10 to 150 keV. The computed DCCs of different organs are found to be in good agreement with data published using other simulation codes. Also, the influence of patient size on DCC values was investigated for a representative body size of the adult Korean patient population. The study was performed using five different sizes covering the range of 0.8-1.2 magnification order of the original HDRK-Man. It focussed on the computation of DCC for the human heart. Moreover, the provided DCCs were used to present an analytical parameterisation for the calculation of the cardiac absorbed dose for any arbitrary X-ray spectrum and for those patient sizes. Thus, the present work can be considered as an enhancement of the continuous studies performed by medical physicist as part of quality control tests and radiation protection dosimetry.

  19. Quantification of absorbed doses to urine bladder depending on drinking water during radioiodine therapy to thyroid cancer patients: a clinical study using MIRDOSE3.

    PubMed

    Sabbir Ahmed, A S M; Demir, M; Yasar, D; Uslu, I

    2003-07-01

    The object of the study was to quantify the absorbed doses to urinary bladder using MIRDOSE3 (medical internal radiation dose package program) depending on drinking water after giving radioiodine dose to thyroid cancer patients. Twenty-nine female thyroid cancer patients (aged 40-60 years, mean 50 years) were selected. The therapeutic doses ranged from 3700 to 7400 MBq of 131I. The radioiodine uptake was measured at 1 cm distance from three organs (previously marked), the thyroid, thigh and stomach, by using a calibrated Eberline ESP-2 GM counter, with a special arrangement of each patient. Urine samples were collected every 12 h for first 72 h, and then every 24 h for the next 96 h. The individual biological half-life of excreted urine was calculated using individual effective half-life. Absorbed doses were calculated for an adult female phantom using the dynamic bladder model of MIRDOSE3 program in two phases: firstly, for different voiding intervals; and secondly, depending on individual drinking water. An average of 85% of the total dose passed through the urinary tract within the first 72 h, with a biological half-life of 28.5+/-0.747 h, and 9% for the next 96 h with a biological half life of 118.43+/-0.645 h. The voiding interval shows great impact on total absorbed dose to bladder and water supplementation needs to be intensified to reduce absorbed doses to bladder wall for the first 3 days.

  20. Reducing absorbed dose to eye lenses in head CT examinations: the effect of bismuth shielding.

    PubMed

    Ciarmatori, Alberto; Nocetti, L; Mistretta, G; Zambelli, G; Costi, T

    2016-06-01

    The eye lens is considered to be among the most radiosensitive human tissues. Brain CT scans may unnecessarily expose it to radiation even if the area of clinical interest is far from the eyes. The aim of this study is to implement a bismuth eye lens shielding system for Head-CT acquisitions in these cases. The study is focused on the assessment of the dosimetric characteristics of the shielding system as well as on its effect on image quality. The shielding system was tested in two set-ups which differ for distance ("contact" and "4 cm" Set up respectively). Scans were performed on a CTDI phantom and an anthropomorphic phantom. A reference set up without shielding system was acquired to establish a baseline. Image quality was assessed by signal (not HU converted), noise and contrast-to-noise ratio (CNR) evaluation. The overall dose reduction was evaluated by measuring the CTDIvol while the eye lens dose reduction was assessed by placing thermoluminescent dosimeters (TLDs) on an anthropomorphic phantom. The image quality analysis exhibits the presence of an artefact that mildly increases the CT number up to 3 cm below the shielding system. Below the artefact, the difference of the Signal and the CNR are negligible between the three different set-ups. Regarding the CTDI, the analysis demonstrates a decrease by almost 12 % (in the "contact" set-up) and 9 % (in the "4 cm" set-up). TLD measurements exhibit an eye lens dose reduction by 28.5 ± 5 and 21.1 ± 5 % respectively at the "contact" and the "4 cm" distance. No relevant artefact was found and image quality was not affected by the shielding system. Significant dose reductions were measured. These features make the shielding set-up useful for clinical implementation in both studied positions.

  1. Measuring radon concentrations and estimating dose in tourist caves.

    PubMed

    Martín Sánchez, A; de la Torre Pérez, J; Ruano Sánchez, A B; Naranjo Correa, F L

    2015-11-01

    Caves and mines are considered to be places of especial risk of exposure to (222)Rn. This is particularly important for guides and workers, but also for visitors. In the Extremadura region (Spain), there are two cave systems in which there are workers carrying out their normal everyday tasks. In one, visits have been reduced to maintain the conditions of temperature and humidity. The other comprises several caves frequently visited by school groups. The caves were radiologically characterised in order to estimate the dose received by workers or possible hazards for visitors.

  2. Tumoral fibrosis effect on the radiation absorbed dose of (177)Lu-Tyr(3)-octreotate and (177)Lu-Tyr(3)-octreotate conjugated to gold nanoparticles.

    PubMed

    Azorín-Vega, E P; Zambrano-Ramírez, O D; Rojas-Calderón, E L; Ocampo-García, B E; Ferro-Flores, G

    2015-06-01

    The aim of this work was to evaluate the tumoral fibrosis effect on the radiation absorbed dose of the radiopharmaceuticals (177)Lu-Tyr(3)-octreotate (monomeric) and (177)Lu-Tyr(3)-octreotate-gold nanoparticles (multimeric) using an experimental HeLa cells tumoral model and the Monte Carlo PENELOPE code. Experimental and computer micro-environment models with or without fibrosis were constructed. Results showed that fibrosis increases up to 33% the tumor radiation absorbed dose, although the major effect on the dose was produced by the type of radiopharmaceutical (112Gy-multimeric vs. 43Gy-monomeric).

  3. Radiation Dose Estimation for Pediatric Patients Undergoing Cardiac Catheterization

    NASA Astrophysics Data System (ADS)

    Wang, Chu

    Patients undergoing cardiac catheterization are potentially at risk of radiation-induced health effects from the interventional fluoroscopic X-ray imaging used throughout the clinical procedure. The amount of radiation exposure is highly dependent on the complexity of the procedure and the level of optimization in imaging parameters applied by the clinician. For cardiac catheterization, patient radiation dosimetry, for key organs as well as whole-body effective, is challenging due to the lack of fixed imaging protocols, unlike other common X-ray based imaging modalities. Pediatric patients are at a greater risk compared to adults due to their greater cellular radio-sensitivities as well as longer remaining life-expectancy following the radiation exposure. In terms of radiation dosimetry, they are often more challenging due to greater variation in body size, which often triggers a wider range of imaging parameters in modern imaging systems with automatic dose rate modulation. The overall objective of this dissertation was to develop a comprehensive method of radiation dose estimation for pediatric patients undergoing cardiac catheterization. In this dissertation, the research is divided into two main parts: the Physics Component and the Clinical Component. A proof-of-principle study focused on two patient age groups (Newborn and Five-year-old), one popular biplane imaging system, and the clinical practice of two pediatric cardiologists at one large academic medical center. The Physics Component includes experiments relevant to the physical measurement of patient organ dose using high-sensitivity MOSFET dosimeters placed in anthropomorphic pediatric phantoms. First, the three-dimensional angular dependence of MOSFET detectors in scatter medium under fluoroscopic irradiation was characterized. A custom-made spherical scatter phantom was used to measure response variations in three-dimensional angular orientations. The results were to be used as angular dependence

  4. Evaluation of absorbed doses in voxel-based and simplified models for small animals.

    PubMed

    Mohammadi, Akram; Kinase, Sakae; Saito, Kimiaki

    2012-07-01

    Internal dosimetry in non-human biota is desirable from the viewpoint of radiation protection of the environment. The International Commission on Radiological Protection (ICRP) proposed Reference Animals and Plants using simplified models, such as ellipsoids and spheres and calculated absorbed fractions (AFs) for whole bodies. In this study, photon and electron AFs in whole bodies of voxel-based rat and frog models have been calculated and compared with AFs in the reference models. It was found that the voxel-based and the reference frog (or rat) models can be consistent for the whole-body AFs within a discrepancy of 25%, as the source was uniformly distributed in the whole body. The specific absorbed fractions (SAFs) and S values were also evaluated in whole bodies and all organs of the voxel-based frog and rat models as the source was distributed in the whole body or skeleton. The results demonstrated that the whole-body SAFs reflect SAFs of all individual organs as the source was uniformly distributed per mass within the whole body by about 30% uncertainties with exceptions for body contour (up to -40%) for both electrons and photons due to enhanced radiation leakages, and for the skeleton for photons only (up to +185%) due to differences in the mass attenuation coefficients. For nuclides such as (90)Y and (90)Sr, which were concentrated in the skeleton, there were large differences between S values in the whole body and those in individual organs, however the whole-body S values for the reference models with the whole body as the source were remarkably similar to those for the voxel-based models with the skeleton as the source, within about 4 and 0.3%, respectively. It can be stated that whole-body SAFs or S values in simplified models without internal organs are not sufficient for accurate internal dosimetry because they do not reflect SAFs or S values of all individual organs as the source was not distributed uniformly in whole body. Thus, voxel-based models

  5. Perspectives on radiation dose estimates for A-bomb survivors

    SciTech Connect

    Loewe, W.E.

    1986-12-01

    Four decades after the actual events, quantitative characterization of the radiation fields at Hiroshima and Nagasaki continues to be sought, with high accuracy a goal justified by the unique contribution to radiation protection standards that is represented by the medical records of exposed survivors. The most recent effort is distinguished by its reliance on computer modeling and concomitant detail, and by its decentralized direction, both internationally and internally to the US and Japan, with resultant ongoing peer review and wide scope of inquiry. A new system for individual dose estimation has been agreed upon, and its scientific basis has been elaborated in the literature as well as in a comprehensive treatise to be published in the Spring of 1987. In perspective, this new system appears to be an unusually successful achievement that offers the expectation of reliable estimates with the desired accuracy. Some aspects leading to this expectation, along with a caveat, are discussed here. 4 refs., 8 figs., 3 tabs.

  6. 324 Building life cycle dose estimates for planned work

    SciTech Connect

    Landsman, S.D.; Peterson, C.A.; Thornhill, R.E.

    1995-09-01

    This report describes a tool for use by organizational management teams to plan, manage, and oversee personnel exposures within their organizations. The report encompasses personnel radiation exposures received from activities associated with the B-Cell Cleanout Project, Surveillance and Maintenance Project, the Mk-42 Project, and other minor activities. It is designed to provide verifiable Radiological Performance Reports. The primary area workers receive radiation exposure is the Radiochemical Engineering Complex airlock. Entry to the airlock is necessary for maintenance of cranes and other equipment, and to set up the rail system used to move large pieces of equipment and shipping casks into and out of the airlock. Transfers of equipment and materials from the hot cells in the complex to the airlock are required to allow dose profiles of waste containers, shuffling of waste containers to allow grouting activities to go on, and to allow maintenance of in-cell cranes. Both DOE and the Pacific Northwest Laboratory (PNL) are currently investing in state-of-the-art decontamination equipment. Challenging goals for exposure reduction were established for several broad areas of activity. Exposure estimates and goals developed from these scheduled activities will be compared against actual exposures for scheduled and unscheduled activities that contributed to exposures received by personnel throughout the year. Included in this report are life cycle exposure estimates by calendar year for the B-Cell Cleanout project, a three-year estimate of exposures associated with Surveillance and Maintenance, and known activities for Calendar Year (CY) 1995 associated with several smaller projects. These reports are intended to provide a foundation for future dose estimates, by year, requiring updating as exposure conditions change or new avenues of approach to performing work are developed.

  7. A radiochromic folm dosimeter for gamma radiation in the absorbed-dose range 0.1-10 kGy

    NASA Astrophysics Data System (ADS)

    Khan, Hasan M.; Farahani, Mahnaz; William L., McLaughlin

    A commercially available leuco-dye film (FWT-63-02), having a thickness of 0.55 mm, has been investigated spectrophotometrically for its characteristics as a radiochromic dosimeter and for its potential use in food-irradiation applications. The γ-ray irradiation of the nearly colorless, transparent film induces blue color with an absorption maximum at 600 nm. The increase in absorbance at 600 nm per unit thickness of film (Δ A mm -1) is linear with dose in the dose range up to 8 kGy, with a slope of 0.91 mm -1·kGy -1. After a modest additional increase during the first day following irradiation, the radiation-induced color is stable when stored at room temperature at least for 5 weeks. The response slope is 16% higher when stored at 60°C, however, after the initial 1-day increase it is stable for several weeks when stored at that temperature. The response of the dosimeter is independent of dose rate in the range 0.5-170 Gy min -1.

  8. 32 CFR 218.4 - Dose estimate reporting standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., and neutron doses, when applicable. In determining the veteran's dose, initial neutron, initial gamma..., doses will be reported as gamma dose, neutron dose, and internal dose. To the extent to which the... of a neutron or internal exposure? What is the reconstruction? Upon request, the participant or...

  9. 32 CFR 218.4 - Dose estimate reporting standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., and neutron doses, when applicable. In determining the veteran's dose, initial neutron, initial gamma..., doses will be reported as gamma dose, neutron dose, and internal dose. To the extent to which the... of a neutron or internal exposure? What is the reconstruction? Upon request, the participant or...

  10. 32 CFR 218.4 - Dose estimate reporting standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., and neutron doses, when applicable. In determining the veteran's dose, initial neutron, initial gamma..., doses will be reported as gamma dose, neutron dose, and internal dose. To the extent to which the... of a neutron or internal exposure? What is the reconstruction? Upon request, the participant or...

  11. 32 CFR 218.4 - Dose estimate reporting standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., and neutron doses, when applicable. In determining the veteran's dose, initial neutron, initial gamma..., doses will be reported as gamma dose, neutron dose, and internal dose. To the extent to which the... of a neutron or internal exposure? What is the reconstruction? Upon request, the participant or...

  12. 32 CFR 218.4 - Dose estimate reporting standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., and neutron doses, when applicable. In determining the veteran's dose, initial neutron, initial gamma..., doses will be reported as gamma dose, neutron dose, and internal dose. To the extent to which the... of a neutron or internal exposure? What is the reconstruction? Upon request, the participant or...

  13. Recent Updates to Radiation Organ Dose Estimation Tool PIMAL

    SciTech Connect

    Akkurt, Hatice; Wiarda, Dorothea; Eckerman, Keith F

    2011-01-01

    A computational phantom with moving arms and legs and an accompanying graphical user interface, PIMAL, was previously developed to enable radiation dose estimation for different postures in a user-friendly manner. This initial version of the software was useful in adjusting the posture, generating the corresponding MCNP input file, and performing the radiation transport simulations for dose calculations using MCNP5 or MCNPX. However, it only included one mathematical phantom model (hermaphrodite) and allowed only isotropic point sources. Recently, the software was enhanced by adding two more mathematical phantom models, a male and female, and the source features were enhanced significantly by adding internal and external source options in a pull-down menu. Although the initial version of the software included only a mathematical hermaphrodite phantom, the features and models in the software are constantly being enhanced by adding more phantoms as well as other options to enable dose assessment for different configurations/cases in a user-friendly manner. In this latest version of the software, ICRP's recently released reference male and female voxel phantoms are included in a pull-down menu. The male and female models are described using 7 and 14 million voxels, respectively. Currently, the software is being modified further to include the International Commission on Radiation Protection's (ICRP) reference male and female voxel phantoms. Additionally, some case studies are being implemented and included in a library of input files. This paper describes recent updates to the software.

  14. Absorbed radiation dosimetry of the D3-specific PET radioligand [18F]FluorTriopride estimated using rodent and nonhuman primate

    PubMed Central

    Laforest, Richard; Karimi, Morvarid; Moerlein, Stephen M; Xu, Jinbin; Flores, Hubert P; Bognar, Christopher; Li, Aixiao; Mach, Robert H; Perlmutter, Joel S; Tu, Zhude

    2016-01-01

    [18F]FluorTriopride ([18F]FTP) is a dopamine D3-receptor preferring radioligand with potential for investigation of neuropsychiatric disorders including Parkinson disease, dystonia and schizophrenia. Here we estimate human radiation dosimetry for [18F]FTP based on the ex-vivo biodistribution in rodents and in vivo distribution in nonhuman primates. Biodistribution data were generated using male and female Sprague-Dawley rats injected with ~370 KBq of [18F]FTP and euthanized at 5, 30, 60, 120, and 240 min. Organs of interest were dissected, weighed and assayed for radioactivity content. PET imaging studies were performed in two male and one female macaque fascicularis administered 143-190 MBq of [18F]FTP and scanned whole-body in sequential sections. Organ residence times were calculated based on organ time activity curves (TAC) created from regions of Interest. OLINDA/EXM 1.1 was used to estimate human radiation dosimetry based on scaled organ residence times. In the rodent, the highest absorbed radiation dose was the upper large intestines (0.32-0.49 mGy/MBq), with an effective dose of 0.07 mSv/MBq in males and 0.1 mSv/MBq in females. For the nonhuman primate, however, the gallbladder wall was the critical organ (1.81 mGy/MBq), and the effective dose was 0.02 mSv/MBq. The species discrepancy in dosimetry estimates for [18F]FTP based on rat and primate data can be attributed to the slower transit of tracer through the hepatobiliary track of the primate compared to the rat, which lacks a gallbladder. Out findings demonstrate that the nonhuman primate model is more appropriate model for estimating human absorbed radiation dosimetry when hepatobiliary excretion plays a major role in radiotracer elimination. PMID:28078183

  15. Absorbed radiation dosimetry of the D3-specific PET radioligand [(18)F]FluorTriopride estimated using rodent and nonhuman primate.

    PubMed

    Laforest, Richard; Karimi, Morvarid; Moerlein, Stephen M; Xu, Jinbin; Flores, Hubert P; Bognar, Christopher; Li, Aixiao; Mach, Robert H; Perlmutter, Joel S; Tu, Zhude

    2016-01-01

    [(18)F]FluorTriopride ([(18)F]FTP) is a dopamine D3-receptor preferring radioligand with potential for investigation of neuropsychiatric disorders including Parkinson disease, dystonia and schizophrenia. Here we estimate human radiation dosimetry for [(18)F]FTP based on the ex-vivo biodistribution in rodents and in vivo distribution in nonhuman primates. Biodistribution data were generated using male and female Sprague-Dawley rats injected with ~370 KBq of [(18)F]FTP and euthanized at 5, 30, 60, 120, and 240 min. Organs of interest were dissected, weighed and assayed for radioactivity content. PET imaging studies were performed in two male and one female macaque fascicularis administered 143-190 MBq of [(18)F]FTP and scanned whole-body in sequential sections. Organ residence times were calculated based on organ time activity curves (TAC) created from regions of Interest. OLINDA/EXM 1.1 was used to estimate human radiation dosimetry based on scaled organ residence times. In the rodent, the highest absorbed radiation dose was the upper large intestines (0.32-0.49 mGy/MBq), with an effective dose of 0.07 mSv/MBq in males and 0.1 mSv/MBq in females. For the nonhuman primate, however, the gallbladder wall was the critical organ (1.81 mGy/MBq), and the effective dose was 0.02 mSv/MBq. The species discrepancy in dosimetry estimates for [(18)F]FTP based on rat and primate data can be attributed to the slower transit of tracer through the hepatobiliary track of the primate compared to the rat, which lacks a gallbladder. Out findings demonstrate that the nonhuman primate model is more appropriate model for estimating human absorbed radiation dosimetry when hepatobiliary excretion plays a major role in radiotracer elimination.

  16. The development of early pediatric models and their application to radiation absorbed dose calculations

    SciTech Connect

    Poston, J.W.

    1989-01-01

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The pediatric'' models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing individual'' pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed.

  17. The development of early pediatric models and their application to radiation absorbed dose calculations

    SciTech Connect

    Poston, J.W.

    1989-12-31

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The ``pediatric`` models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing ``individual`` pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed.

  18. Influence of the electron energy and number of beams on the absorbed dose distributions in radiotherapy of deep seated targets.

    PubMed

    Garnica-Garza, H M

    2014-12-01

    With the advent of compact laser-based electron accelerators, there has been some renewed interest on the use of such charged particles for radiotherapy purposes. Traditionally, electrons have been used for the treatment of fairly superficial lesions located at depths of no more than 4cm inside the patient, but lately it has been proposed that by using very high energy electrons, i.e. those with an energy in the order of 200-250MeV it should be possible to safely reach deeper targets. In this paper, we used a realistic patient model coupled with detailed Monte Carlo simulations of the electron transport in such a patient model to examine the characteristics of the resultant absorbed dose distributions as a function of both the electron beam energy as well as the number of beams for a particular type of treatment, namely, a prostate radiotherapy treatment. Each treatment is modeled as consisting of nine, five or three beam ports isocentrically distributed around the patient. An optimization algorithm is then applied to obtain the beam weights in each treatment plan. It is shown that for this particularly challenging case, both excellent target coverage and critical structure sparing can be obtained for energies in the order of 150MeV and for as few as three treatment ports, while significantly reducing the total energy absorbed by the patient with respect to a conventional megavoltage x-ray treatment.

  19. A dosimetric evaluation of tissue equivalent phantom prepared using 270 Bloom gelatin for absorbed dose imaging in Gamma knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Cavinato, C. C.; Rodrigues, O., Jr.; Cervantes, J. H.; Rabbani, S. R.; Campos, L. L.

    2009-05-01

    Tissue equivalent gel phantoms have been widely studied in radiation therapy for both relative and reference dosimetry. A Fricke xylenol gel (FXG) spherical phantom was evaluated by means of magnetic resonance image method (MRI) to measure absorbed dose distribution resulted from gamma knife irradiation. The FXG phantom was prepared using 270 Bloom gelatin. The gelatin is a tissue equivalent material, of easy preparation, can be used to mold phantoms into different shapes and volumes, is commercially available and inexpensive. The results show that the Fricke gel phantom prepared with 270 Bloom gelatin satisfy the requirements to be used for the quality control in stereotactic radiosurgery using Gamma Knife technique and may constitute one more option of dosimeter in radiation therapy applications.

  20. Estimation of organ and effective dose to the patient during spinal surgery with a cone-beam O-arm system

    NASA Astrophysics Data System (ADS)

    Söderberg, Marcus; Abul-Kasim, Kasim; Ohlin, Acke; Gunnarsson, Mikael

    2011-03-01

    The purpose of this study was to estimate organ and effective dose to the patient during spinal surgery with a cone-beam O-arm system. The absorbed dose to radiosensitive organs and effective dose were calculated on mathematically simulated phantom corresponding to a 15-year-old patient using PCXMC 2.0. Radiation doses were calculated at every 15° of the x-ray tube projection angle at two regions: thoracic spine and lumbar spine. Two different scan settings were investigated: 120 kV/128 mAs (standard) and 80 kV/80 mAs (low-dose). The effect on effective dose by changing the number of simulated projection angles (24, 12 and 4) was investigated. Estimated effective dose with PCXMC was compared with calculated effective dose using conversion factors between dose length product (DLP) and effective dose. The highest absorbed doses were received by the breast, lungs (thoracic spine) and stomach (lumbar spine). The effective doses using standard settings were 5 times higher than those delivered with low-dose settings (2-3 scans: 7.9-12 mSv versus 1.5-2.4 mSv). There was no difference in estimated effective dose using 24 or 12 projection angles. Using 4 projection angles at every 90° was not enough to accurate simulate the x-ray tube rotating around the patient. Conversion factors between DLP and effective dose were determined. Our conclusion is that the O-arm has the potential to deliver high radiation doses and consequently there is a strong need to optimize the clinical scan protocols.

  1. Estimation of columnar concentrations of absorbing and scattering fine mode aerosol components using AERONET data

    NASA Astrophysics Data System (ADS)

    Choi, Yongjoo; Ghim, Young Sung

    2016-11-01

    Columnar concentrations of absorbing and scattering components of fine mode aerosols were estimated using Aerosol Robotic Network (AERONET) data for a site downwind of Seoul. The study period was between March 2012 and April 2013 including the period of the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-Asia campaign in March to May 2012. The Maxwell Garnett mixing rule was assumed for insoluble components embedded in a host solution, while the volume average mixing rule was assumed for the aqueous solution of soluble components. During the DRAGON-Asia campaign the surface concentrations of major components of fine particles were measured. The columnar mass fractions of black carbon (BC), organic carbon (OC), mineral dust (MD), and ammonium sulfate (AS) were 1.5, 5.9, 6.6, and 52%, respectively, which were comparable to the mass fractions measured at the surface for BC, OC, and secondary inorganic aerosols at 2.3, 18, and 55%. The vertical distributions of BC and AS were investigated by employing the concept of a column height. While the column height for BC was similar to the planetary boundary layer (PBL) height, that for AS was 4.4 times higher than the PBL height and increased with air temperature from March to May. The monthly variations of the columnar mass concentrations during the study period were generally well explained in term of meteorology and emission characteristics. However, certain variations of MD were different from those typically observed primarily because only fine mode aerosols were considered.

  2. Absorbed dose evaluation of Auger electron-emitting radionuclides: impact of input decay spectra on dose point kernels and S-values

    NASA Astrophysics Data System (ADS)

    Falzone, Nadia; Lee, Boon Q.; Fernández-Varea, José M.; Kartsonaki, Christiana; Stuchbery, Andrew E.; Kibédi, Tibor; Vallis, Katherine A.

    2017-03-01

    The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model BrIccEmis on dose point kernels (DPKs - radial dose distribution around a unit point source) and S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely 67Ga, 80mBr, 89Zr, 90Nb, 99mTc, 111In, 117mSn, 119Sb, 123I, 124I, 125I, 135La, 195mPt and 201Tl. Radiation spectra were based on the nuclear decay data from the medical internal radiation dose (MIRD) RADTABS program and the BrIccEmis code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. S-values for concentric spherical cells of various sizes were derived from these DPKs using appropriate geometric reduction factors. The number of Auger and Coster–Kronig (CK) electrons and x-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using BrIccEmis. DPKs for the electron spectra from BrIccEmis were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. S-values were, however, not significantly impacted as the differences in DPKs in the sub-micrometre dimension were quickly diminished in larger dimensions. Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions.

  3. Absorbed dose evaluation of Auger electron-emitting radionuclides: impact of input decay spectra on dose point kernels and S-values.

    PubMed

    Falzone, Nadia; Lee, Boon Q; Fernández-Varea, José M; Kartsonaki, Christiana; Stuchbery, Andrew E; Kibédi, Tibor; Vallis, Katherine A

    2017-03-21

    The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model BrIccEmis on dose point kernels (DPKs - radial dose distribution around a unit point source) and S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely (67)Ga, (80m)Br, (89)Zr, (90)Nb, (99m)Tc, (111)In, (117m)Sn, (119)Sb, (123)I, (124)I, (125)I, (135)La, (195m)Pt and (201)Tl. Radiation spectra were based on the nuclear decay data from the medical internal radiation dose (MIRD) RADTABS program and the BrIccEmis code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. S-values for concentric spherical cells of various sizes were derived from these DPKs using appropriate geometric reduction factors. The number of Auger and Coster-Kronig (CK) electrons and x-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using BrIccEmis. DPKs for the electron spectra from BrIccEmis were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. S-values were, however, not significantly impacted as the differences in DPKs in the sub-micrometre dimension were quickly diminished in larger dimensions. Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions.

  4. Development of in vivo tooth EPR for individual radiation dose estimation and screening.

    PubMed

    Williams, Benjamin B; Dong, Ruhong; Kmiec, Maciej; Burke, Greg; Demidenko, Eugene; Gladstone, David; Nicolalde, Roberto J; Sucheta, Artur; Lesniewski, Piotr; Swartz, Harold M

    2010-02-01

    The development of in vivo EPR has made it feasible to perform tooth dosimetry measurements in situ, greatly expanding the potential for using this approach for immediate screening after radiation exposures. The ability of in vivo tooth dosimetry to provide estimates of absorbed dose has been established through a series of experiments using unirradiated volunteers with specifically irradiated molar teeth placed in situ within gaps in their dentition and in natural canine teeth of patients who have completed courses of radiation therapy for head and neck cancers. Multiple measurements in patients who have received radiation therapy demonstrate the expected heterogeneous dose distributions. Dose-response curves have been generated using both populations and, using the current methodology and instrument, the standard error of prediction based on single 4.5-min measurements is approximately 1.5 Gy for inserted molar teeth and between 2.0 and 2.5 Gy in the more irregularly shaped canine teeth. Averaging of independent measurements can reduce this error significantly to values near 1 Gy. Developments to reduce these errors are underway, focusing on geometric optimization of the resonators, detector positioning techniques, and optimal data averaging approaches. In summary, it seems plausible that the EPR dosimetry techniques will have an important role in retrospective dosimetry for exposures involving large numbers of individuals.

  5. Development of In Vivo Tooth EPR for Individual Radiation Dose Estimation and Screening

    PubMed Central

    Williams, Benjamin B.; Dong, Ruhong; Kmiec, Maciej; Burke, Greg; Demidenko, Eugene; Gladstone, David; Nicolalde, Roberto J; Sucheta, Artur; Lesniewski, Piotr; Swartz, Harold M

    2009-01-01

    The development of in vivo EPR has made it feasible to perform tooth dosimetry measurements in situ, greatly expanding the potential for using this approach for immediate screening after radiation exposures. The ability of in vivo tooth dosimetry to provide estimates of absorbed dose has been established through a series of experiments using unirradiated volunteers with specifically irradiated molar teeth placed in situ within gaps in their dentition and in natural canine teeth of patients who have completed courses of radiation therapy for head and neck cancers. Multiple measurements in patients who have received radiation therapy demonstrate the expected heterogeneous dose distributions. Dose response curves have been generated using both populations and, using the current methodology and instrument, the standard error of prediction based on single 4.5 minute measurements is approximately 1.5 Gy for inserted molar teeth and between 2.0 and 2.5 Gy in the more irregularly shaped canine teeth. Averaging of independent measurements can reduce this error significantly to values near 1 Gy. Developments to reduce these errors are underway, focusing on geometric optimization of the resonators, detector positioning techniques, and optimal data averaging approaches. In summary, it seems plausible that the EPR dosimetry techniques will have an important role in retrospective dosimetry for exposures involving large numbers of individuals. PMID:20065702

  6. Effect of Anatomical Modeling on Space Radiation Dose Estimates: A Comparison of Doses for NASA Phantoms and 5th, 50th, and 95th Percentile UF Hybrid Phantoms

    NASA Technical Reports Server (NTRS)

    Bahadori, A.; VanBaalen, M.; Shavers, M.; Semones, E.; Dodge, C.; Bolch, W.

    2010-01-01

    The estimate of absorbed dose to individual organs of a space crewmember is affected by the geometry of the anatomical model of the astronaut used in the radiation transport calculation. For astronaut dosimetry, NASA currently uses the computerized anatomical male (CAM) and computerized anatomical female (CAF) stylized phantoms to represent astronauts in its operational radiation dose analyses. These phantoms are available in one size and in two body positions. In contrast, the UF Hybrid Adult Male and Female (UFHADM and UFHADF) phantoms have organ shapes based on actual CT data. The surfaces of these phantoms are defined by non-uniform rational B-spline surfaces, and are thus flexible in terms of body morphometry and extremity positioning. In this study, UFHADM and UFHADF are scaled to dimensions corresponding to 5th, 50th, and 95th percentile (PCTL) male and female astronauts. A ray-tracing program is written in Visual Basic 2008, which is then used to create areal density maps for dose points corresponding to various organs within the phantoms. The areal density maps, along with appropriate space radiation spectra, are input into the NASA program couplet HZETRN/BRYNTRN, and organ doses are calculated. The areal density maps selected tissues and organs of the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared. In addition, the organ doses for the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared to organ doses for CAM and CAF.

  7. Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Hasanzadeh, H.; Sharafi, A.; Allah Verdi, M.; Nikoofar, A.

    2006-09-01

    Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 ± 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 ± 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 ± 15.1 cGy, 9.15 ± 3.89 cGy, 0.47 ± 0.3 cGy and 0.53 ± 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours.

  8. Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery.

    PubMed

    Hasanzadeh, H; Sharafi, A; Allah Verdi, M; Nikoofar, A

    2006-09-07

    Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 +/- 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 +/- 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 +/- 15.1 cGy, 9.15 +/- 3.89 cGy, 0.47 +/- 0.3 cGy and 0.53 +/- 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours.

  9. Organ/Tissue absorbed doses measured with a human phantom torso in the 9th Shuttle-Mir Mission (STS-91).

    PubMed

    Yasuda, H; Komiyama, T; Fujitaka, K

    1999-09-01

    Organ/Tissue absorbed doses were measured with a life-size human phantom torso in the 9th Shuttle/Mir Mission (STS-91) from June 2 to 12, 1998. This is the first attempt to measure directly organ/tissue doses over a whole human body in space. The absorbed dose was measured by combination of two integrating detectors: thermo- luminescent dosemeter of Mg2SiO4: Tb (TDMS) and plastic nuclear track detector (PNTD). Both detectors were calibrated on ground using high-energy charged-particle beams. The detectors were packed in 59 cases of tissue-equivalent resin; and put into the positions of radiologically important organs and tissues in the phantom. Efficiency reductions of TDMS for high-LET particles were corrected based on the LET-differential particle fluence of space radiation measured with PNTDs. The accumulated absorbed doses during this 9.8-days mission at low-earth orbit (400 km x 51.6 degrees) ranged from 1.6 mGy at colon to 2.6 mGy at bone surface (shoulder) with a variation factor of 1.6. The absorbed doses at some internal organs were higher than the skin dose. This fact is important from the viewpoint of radiological protection for astronauts.

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

    PubMed

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

    2015-05-01

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

  11. Estimated radiation dose to breast feeding infant following maternal administration of 57Co labelled to vitamin B12.

    PubMed

    Pomeroy, Kay M; Sawyer, Laura J; Evans, Martyn J

    2005-09-01

    Administration of a radiopharmaceutical may result in a radiation dose to an infant due to ingestion of the radiopharmaceutical secreted in the breast milk. Following a maternal administration of Co labelled to vitamin B12 (cyanocobalamin) as part of a Schilling test an estimate of the absorbed dose to a breast feeding infant was calculated. Milk samples were collected from every feed in the first 24 h, and at approximately 48 and 72 h post-administration. The absorbed dose to the infant's liver (the organ receiving the highest dose) was calculated to be 0.23 mGy. The effective dose to the infant was calculated to be 0.025 mSv, which is considerably lower than the current regulatory limit of 1 mSv. The Administration of Radioactive Substances Advisory Committee advise that the first feed, at approximately 4 h after administration, be discarded. The data show that this was unwarranted, and that the peak concentration of Co in the breast milk occurred at around 24 h.

  12. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    SciTech Connect

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A'aisah; Ahmad, Pauzi

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  13. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    NASA Astrophysics Data System (ADS)

    Bakar, Khomsaton Abu; Ahmad, Pauzi; Zulkafli, Hashim, Siti A'aisah

    2014-09-01

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  14. Radiation signature on exposed cells: Relevance in dose estimation.

    PubMed

    Perumal, Venkatachalam; Gnana Sekaran, Tamizh Selvan; Raavi, Venkateswarlu; Basheerudeen, Safa Abdul Syed; Kanagaraj, Karthik; Chowdhury, Amith Roy; Paul, Solomon Fd

    2015-09-28

    The radiation is considered as a double edged sword, as its beneficial and detrimental effects have been demonstrated. The potential benefits are being exploited to its maximum by adopting safe handling of radionuclide stipulated by the regulatory agencies. While the occupational workers are monitored by personnel monitoring devices, for general publics, it is not a regular practice. However, it can be achieved by using biomarkers with a potential for the radiation triage and medical management. An ideal biomarker to adopt in those situations should be rapid, specific, sensitive, reproducible, and able to categorize the nature of exposure and could provide a reliable dose estimation irrespective of the time of the exposures. Since cytogenetic markers shown to have many advantages relatively than other markers, the origins of various chromosomal abnormalities induced by ionizing radiations along with dose-response curves generated in the laboratory are presented. Current status of the gold standard dicentric chromosome assay, micronucleus assay, translocation measurement by fluorescence in-situ hybridization and an emerging protein marker the γ-H2AX assay are discussed with our laboratory data. With the wide choice of methods, an appropriate assay can be employed based on the net.

  15. Radiation signature on exposed cells: Relevance in dose estimation

    PubMed Central

    Perumal, Venkatachalam; Gnana Sekaran, Tamizh Selvan; Raavi, Venkateswarlu; Basheerudeen, Safa Abdul Syed; Kanagaraj, Karthik; Chowdhury, Amith Roy; Paul, Solomon FD

    2015-01-01

    The radiation is considered as a double edged sword, as its beneficial and detrimental effects have been demonstrated. The potential benefits are being exploited to its maximum by adopting safe handling of radionuclide stipulated by the regulatory agencies. While the occupational workers are monitored by personnel monitoring devices, for general publics, it is not a regular practice. However, it can be achieved by using biomarkers with a potential for the radiation triage and medical management. An ideal biomarker to adopt in those situations should be rapid, specific, sensitive, reproducible, and able to categorize the nature of exposure and could provide a reliable dose estimation irrespective of the time of the exposures. Since cytogenetic markers shown to have many advantages relatively than other markers, the origins of various chromosomal abnormalities induced by ionizing radiations along with dose-response curves generated in the laboratory are presented. Current status of the gold standard dicentric chromosome assay, micronucleus assay, translocation measurement by fluorescence in-situ hybridization and an emerging protein marker the γ-H2AX assay are discussed with our laboratory data. With the wide choice of methods, an appropriate assay can be employed based on the net. PMID:26435777

  16. Dose estimation using dicentric chromosome assay and cytokinesis block micronucleus assay: comparison between manual and automated scoring in triage mode.

    PubMed

    De Amicis, Andrea; De Sanctis, Stefania; Di Cristofaro, Sara; Franchini, Valeria; Regalbuto, Elisa; Mammana, Giacomo; Lista, Florigio

    2014-06-01

    In cases of an accidental overexposure to ionizing radiation, it is essential to estimate the individual absorbed dose of a potentially radiation-exposed person. For this purpose, biological dosimetry can be performed to confirm, complement or even replace physical dosimetry when this proves to be unavailable. The most validated biodosimetry techniques for dose estimation are the dicentric chromosome assay, the "gold standard" for individual dose assessment, and cytokinesis-block micronucleus assay. However, both assays are time consuming and require skilled scorers. In case of large-scale accidents, different strategies have been developed to increase the throughput of cytogenetic service laboratories. These are the decrease of cell numbers to be scored for triage dosimetry; the automation of procedures including the scoring of, for example, aberrant chromosomes and micronuclei; and the establishment of laboratory networks in order to enable mutual assistance if necessary. In this study, the authors compared the accuracy of triage mode biodosimetry by dicentric chromosome analysis and the cytokinesis block micronucleus assay performing both the manual and the automated scoring mode. For dose estimation using dicentric chromosome assay of 10 blind samples irradiated up to 6.4 Gy of x-rays, a number of metaphase spreads were analyzed ranging from 20 up to 50 cells for the manual and from 20 up to 500 cells for the automatic scoring mode. For dose estimation based on the cytokinesis block micronucleus assay, the micronucleus frequency in both 100 and 200 binucleated cells was determined by manual and automatic scoring. The results of both assays and scoring modes were compared and analyzed considering the sensitivity, specificity, and accuracy of dose estimation with regard to the discrimination power of clinically relevant binary categories of exposure doses.

  17. Optimizing CT radiation dose based on patient size and image quality: the size-specific dose estimate method.

    PubMed

    Larson, David B

    2014-10-01

    The principle of ALARA (dose as low as reasonably achievable) calls for dose optimization rather than dose reduction, per se. Optimization of CT radiation dose is accomplished by producing images of acceptable diagnostic image quality using the lowest dose method available. Because it is image quality that constrains the dose, CT dose optimization is primarily a problem of image quality rather than radiation dose. Therefore, the primary focus in CT radiation dose optimization should be on image quality. However, no reliable direct measure of image quality has been developed for routine clinical practice. Until such measures become available, size-specific dose estimates (SSDE) can be used as a reasonable image-quality estimate. The SSDE method of radiation dose optimization for CT abdomen and pelvis consists of plotting SSDE for a sample of examinations as a function of patient size, establishing an SSDE threshold curve based on radiologists' assessment of image quality, and modifying protocols to consistently produce doses that are slightly above the threshold SSDE curve. Challenges in operationalizing CT radiation dose optimization include data gathering and monitoring, managing the complexities of the numerous protocols, scanners and operators, and understanding the relationship of the automated tube current modulation (ATCM) parameters to image quality. Because CT manufacturers currently maintain their ATCM algorithms as secret for proprietary reasons, prospective modeling of SSDE for patient populations is not possible without reverse engineering the ATCM algorithm and, hence, optimization by this method requires a trial-and-error approach.

  18. Environmental radioactivity in the UK: the airborne geophysical view of dose rate estimates.

    PubMed

    Beamish, David

    2014-12-01

    This study considers UK airborne gamma-ray data obtained through a series of high spatial resolution, low altitude surveys over the past decade. The ground concentrations of the naturally occurring radionuclides Potassium, Thorium and Uranium are converted to air absorbed dose rates and these are used to assess terrestrial exposure levels from both natural and technologically enhanced sources. The high resolution airborne information is also assessed alongside existing knowledge from soil sampling and ground-based measurements of exposure levels. The surveys have sampled an extensive number of the UK lithological bedrock formations and the statistical information provides examples of low dose rate lithologies (the formations that characterise much of southern England) to the highest sustained values associated with granitic terrains. The maximum dose rates (e.g. >300 nGy h(-1)) encountered across the sampled granitic terrains are found to vary by a factor of 2. Excluding granitic terrains, the most spatially extensive dose rates (>50 nGy h(-1)) are found in association with the Mercia Mudstone Group (Triassic argillaceous mudstones) of eastern England. Geological associations between high dose rate and high radon values are also noted. Recent studies of the datasets have revealed the extent of source rock (i.e. bedrock) flux attenuation by soil moisture in conjunction with the density and porosity of the temperate latitude soils found in the UK. The presence or absence of soil cover (and associated presence or absence of attenuation) appears to account for a range of localised variations in the exposure levels encountered. The hypothesis is supported by a study of an extensive combined data set of dose rates obtained from soil sampling and by airborne geophysical survey. With no attenuation factors applied, except those intrinsic to the airborne estimates, a bias to high values of between 10 and 15 nGy h(-1) is observed in the soil data. A wide range of

  19. Angular distributions of absorbed dose of Bremsstrahlung and secondary electrons induced by 18-, 28- and 38-MeV electron beams in thick targets.

    PubMed

    Takada, Masashi; Kosako, Kazuaki; Oishi, Koji; Nakamura, Takashi; Sato, Kouichi; Kamiyama, Takashi; Kiyanagi, Yoshiaki

    2013-03-01

    Angular distributions of absorbed dose of Bremsstrahlung photons and secondary electrons at a wide range of emission angles from 0 to 135°, were experimentally obtained using an ion chamber with a 0.6 cm(3) air volume covered with or without a build-up cap. The Bremsstrahlung photons and electrons were produced by 18-, 28- and 38-MeV electron beams bombarding tungsten, copper, aluminium and carbon targets. The absorbed doses were also calculated from simulated photon and electron energy spectra by multiplying simulated response functions of the ion chambers, simulated with the MCNPX code. Calculated-to-experimental (C/E) dose ratios obtained are from 0.70 to 1.57 for high-Z targets of W and Cu, from 15 to 135° and the C/E range from 0.6 to 1.4 at 0°; however, the values of C/E for low-Z targets of Al and C are from 0.5 to 1.8 from 0 to 135°. Angular distributions at the forward angles decrease with increasing angles; on the other hand, the angular distributions at the backward angles depend on the target species. The dependences of absorbed doses on electron energy and target thickness were compared between the measured and simulated results. The attenuation profiles of absorbed doses of Bremsstrahlung beams at 0, 30 and 135° were also measured.

  20. SU-E-CAMPUS-I-06: Y90 PET/CT for the Instantaneous Determination of Both Target and Non-Target Absorbed Doses Following Hepatic Radioembolization

    SciTech Connect

    Pasciak, A; Kao, J

    2014-06-15

    Purpose The process of converting Yttrium-90 (Y90) PET/CT images into 3D absorbed dose maps will be explained. The simple methods presented will allow the medical physicst to analyze Y90 PET images following radioembolization and determine the absorbed dose to tumor, normal liver parenchyma and other areas of interest, without application of Monte-Carlo radiation transport or dose-point-kernel (DPK) convolution. Methods Absorbed dose can be computed from Y90 PET/CT images based on the premise that radioembolization is a permanent implant with a constant relative activity distribution after infusion. Many Y90 PET/CT publications have used DPK convolution to obtain 3D absorbed dose maps. However, this method requires specialized software limiting clinical utility. The Local Deposition method, an alternative to DPK convolution, can be used to obtain absorbed dose and requires no additional computer processing. Pixel values from regions of interest drawn on Y90 PET/CT images can be converted to absorbed dose (Gy) by multiplication with a scalar constant. Results There is evidence that suggests the Local Deposition method may actually be more accurate than DPK convolution and it has been successfully used in a recent Y90 PET/CT publication. We have analytically compared dose-volume-histograms (DVH) for phantom hot-spheres to determine the difference between the DPK and Local Deposition methods, as a function of PET scanner point-spread-function for Y90. We have found that for PET/CT systems with a FWHM greater than 3.0 mm when imaging Y90, the Local Deposition Method provides a more accurate representation of DVH, regardless of target size than DPK convolution. Conclusion Using the Local Deposition Method, post-radioembolization Y90 PET/CT images can be transformed into 3D absorbed dose maps of the liver. An interventional radiologist or a Medical Physicist can perform this transformation in a clinical setting, allowing for rapid prediction of treatment efficacy by

  1. Estimation of beta-ray skin dose from exposure to fission fallout from the Hiroshima atomic bomb.

    PubMed

    Endo, Satoru; Tanaka, Kenichi; Shizuma, Kiyoshi; Hoshi, Masaharu; Imanaka, Tetsuji

    2012-03-01

    Beta-ray skin dose due to the fission fallout from the Hiroshima atomic bomb is potentially related to the epilation in the black rain area. The absorbed dose to the skin from beta-rays emitted by fission fallout has been estimated for an initial ¹³⁷Cs deposition of 1 kBq m⁻² on the ground at 0.5 h after the explosion. The estimated skin dose takes into account both external exposure from fission fallout radionuclides uniformly distributed in 1 mm of soil on the surface of the ground and from a 26 μm thickness of contaminated soil on the skin, using the Monte Carlo radiation transport code MCNP-4C. The cumulative skin dose for 1 month after the explosion is taken as the representative value. The estimated skin dose for an initial ¹³⁷Cs deposition of 1 kBq m⁻² was determined to be about 500 mSv.

  2. SU-E-T-204: Comparison of Absorbed-Dose to Water in High-Energy Photon Beams Based On Addendum AAPM TG-51, IAEA TRS-398, and JSMP 12

    SciTech Connect

    Kinoshita, N; Kita, A; Yoshioka, C; Sasamoto, K; Nishimoto, Y; Adachi, T; Oguchi, H; Shioura, H; Kimura, H

    2015-06-15

    Purpose: Several clinical reference dosimetry protocols for absorbed-dose to water have recently been published: The American Association of Physicists in Medicine (AAPM) published an Addendum to the AAPM’s TG-51 (Addendum TG-51) in April 2014, and the Japan Society of Medical Physics (JSMP) published the Japan Society of Medical Physics 12 (JSMP12), a clinical reference dosimetry protocol, in September 2012. This investigation compared and evaluated the absorbed-dose to water of high-energy photon beams according to Addendum TG-51, International Atomic Energy Agency Technical Report Series No. 398 (TRS-398), and JSMP12. Methods: Differences in the respective beam quality conversion factors with Addendum TG-51, TRS-398, and JSMP12 were analyzed and the absorbed-dose to water using 6- and 10-MV photon beams was measured according to the protocols recommended in Addendum TG-51, TRS-398, and JSMP12. The measurements were conducted using two Farmer-type ionization chambers, Exradin A12 and PTW 30013. Results: The beam quality conversion factors for both the 6- and 10-MV photon beams with Addendum TG-51 were within 0.6%, in agreement with the beam quality conversion factors with TRS-398 and JSMP12. The Exradin A12 provided an absorbed-dose to water ratio from 1.003 to 1.006 with TRS-398 / Addendum TG-51 and from 1.004 to 1.005 with JSMP 12 / Addendum TG-51, whereas the PTW 30013 provided a ratio of 1.001 with TRS-398 / Addendum TG-51 and a range from 0.997 to 0.999 with JSMP 12 / Addendum TG-51. Conclusion: Despite differences in the beam quality conversion factor, no major differences were seen in the absorbed-dose to water with Addendum TG-51, TRS-398, and JSMP12. However, Addendum TG-51 provides the most recent data for beam quality conversion factors based on Monte Carlo simulation and greater detail for the measurement protocol. Therefore, the absorbed-dose to water measured with Addendum TG-51 is an estimate with less uncertainty.

  3. Deuterons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2011-01-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons ((2)H(+)) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by <3%. The greatest difference, 47%, occurred at 30 MeV.

  4. SU-E-T-516: Measurement of the Absorbed Dose Rate in Water Under Reference Conditions in a CyberKnife Unit

    SciTech Connect

    Aragon-Martinez, N; Hernandez-Guzman, A; Gomez-Munoz, A; Massillon-JL, G

    2014-06-01

    Purpose: This paper aims to measure the absorbed-dose-rate in a CyberKnife unit reference-field (6cm diameter) using three ionization chambers (IC) following the new IAEA/AAPM formalism and Gafchromic film (MD-V3-55 and EBT3) protocol according to our work reported previously. Methods: The absorbed-dose-rates were measured at 90cm and 70cm SSD in a 10cmx10cm field and at 70cm SSD in a 5.4cmx5.4cm equivalent to 6cm diameter field using a linac Varian iX. All measurements were performed at 10cm depth in water. The correction factors that account for the difference between the IC response on the reference field and the CyberKnife reference field, k-(Q-msr,Q)^(f-msr,f-ref), were evaluated and Gafchromic film were calibrated using the results obtained above. Under the CyberKnife reference conditions, the factors were used to measure the absorbed-dose-rate with IC according to the new formalism and the calibrated film was irradiated in water. The film calibration curve was used to evaluate the absorbed-dose-rate in the CyberKnife unit. Results: Difference up to 2.56% is observed between dose-rate measured with IC in the reference 10cmx10cm field, depending where the chamber was calibrated, which was not reflected in the correction factor k-(Q-msr,Q)^(f-msr,f-ref ) where variations of ~0.15%-0.5% were obtained. Within measurements uncertainties, maximum difference of 1.8% on the absorbed-dose-rate in the CyberKnife reference field is observed between all IC and the films Conclusion: Absorbed-dose-rate to water was measured in a CyberKnife reference field with acceptable accuracy (combined uncertainties ~1.32%-1.73%, k=1) using three IC and films. The MD-V3-55 film as well as the new IAEA/AAPM formalism can be considered as a suitable dosimetric method to measure absorbed-dose-rate to water in small and non-standard CyberKnife fields used in clinical treatments However, the EBT3 film is not appropriated due to the high uncertainty provided (combined uncertainty ~9%, k=1

  5. Relative Importance of Hip and Sacral Pain Among Long-Term Gynecological Cancer Survivors Treated With Pelvic Radiotherapy and Their Relationships to Mean Absorbed Doses

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Alevronta, Eleftheria; Al-Abany, Massoud; Tucker, Susan; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2012-10-01

    Purpose: To investigate the relative importance of patient-reported hip and sacral pain after pelvic radiotherapy (RT) for gynecological cancer and its relationship to the absorbed doses in these organs. Methods and Materials: We used data from a population-based study that included 650 long-term gynecological cancer survivors treated with pelvic RT in the Gothenburg and Stockholm areas in Sweden with a median follow-up of 6 years (range, 2-15) and 344 population controls. Symptoms were assessed through a study-specific postal questionnaire. We also analyzed the hip and sacral dose-volume histogram data for 358 of the survivors. Results: Of the survivors, one in three reported having or having had hip pain after completing RT. Daily pain when walking was four times as common among the survivors compared to controls. Symptoms increased in frequency with a mean absorbed dose >37.5 Gy. Also, two in five survivors reported pain in the sacrum. Sacral pain also affected their walking ability and tended to increase with a mean absorbed dose >42.5 Gy. Conclusions: Long-term survivors of gynecological cancer treated with pelvic RT experience hip and sacral pain when walking. The mean absorbed dose was significantly related to hip pain and was borderline significantly related to sacral pain. Keeping the total mean absorbed hip dose below 37.5 Gy during treatment might lower the occurrence of long-lasting pain. In relation to the controls, the survivors had a lower occurrence of pain and pain-related symptoms from the hips and sacrum compared with what has previously been reported for the pubic bone.

  6. Estimates of radiation doses in tissue and organs and risk of excess cancer in the single-course radiotherapy patients treated for ankylosing spondylitis in England and Wales

    SciTech Connect

    Fabrikant, J.I.; Lyman, J.T.

    1982-02-01

    The estimates of absorbed doses of x rays and excess risk of cancer in bone marrow and heavily irradiated sites are extremely crude and are based on very limited data and on a number of assumptions. Some of these assumptions may later prove to be incorrect, but it is probable that they are correct to within a factor of 2. The excess cancer risk estimates calculated compare well with the most reliable epidemiological surveys thus far studied. This is particularly important for cancers of heavily irradiated sites with long latent periods. The mean followup period for the patients was 16.2 y, and an increase in cancers of heavily irradiated sites may appear in these patients in the 1970s in tissues and organs with long latent periods for the induction of cancer. The accuracy of these estimates is severely limited by the inadequacy of information on doses absorbed by the tissues at risk in the irradiated patients. The information on absorbed dose is essential for an accurate assessment of dose-cancer incidence analysis. Furthermore, in this valuable series of irradiated patients, the information on radiation dosimetry on the radiotherapy charts is central to any reliable determination of somatic risks of radiation with regard to carcinogenesis in man. The work necessary to obtain these data is under way; only when they are available can more precise estimates of risk of cancer induction by radiation in man be obtained.

  7. The effect of systematic set-up deviations on the absorbed dose distribution for left-sided breast cancer treated with respiratory gating

    NASA Astrophysics Data System (ADS)

    Edvardsson, A.; Ceberg, S.

    2013-06-01

    The aim of this study was 1) to investigate interfraction set-up uncertainties for patients treated with respiratory gating for left-sided breast cancer, 2) to investigate the effect of the inter-fraction set-up on the absorbed dose-distribution for the target and organs at risk (OARs) and 3) optimize the set-up correction strategy. By acquiring multiple set-up images the systematic set-up deviation was evaluated. The effect of the systematic set-up deviation on the absorbed dose distribution was evaluated by 1) simulation in the treatment planning system and 2) measurements with a biplanar diode array. The set-up deviations could be decreased using a no action level correction strategy. Not using the clinically implemented adaptive maximum likelihood factor for the gating patients resulted in better set-up. When the uncorrected set-up deviations were simulated the average mean absorbed dose was increased from 1.38 to 2.21 Gy for the heart, 4.17 to 8.86 Gy to the left anterior descending coronary artery and 5.80 to 7.64 Gy to the left lung. Respiratory gating can induce systematic set-up deviations which would result in increased mean absorbed dose to the OARs if not corrected for and should therefore be corrected for by an appropriate correction strategy.

  8. Transfer of the UK absorbed dose primary standard for photon beams from the research linac to the clinical linac at NPL

    NASA Astrophysics Data System (ADS)

    Pearce, J. A. D.; Shipley, D. R.; Duane, S.

    2011-10-01

    An Elekta Synergy clinical linac facility is now in routine use at the National Physical Laboratory (NPL). For the purpose of therapy-level dosimetry, this has replaced the NPL research linac, which is over 40 years old, and in which the NPL absorbed dose primary standard for high-energy photons was established. This standard has been disseminated to clinical beams by interpolation of the calibration factor as a function of tissue phantom ratio TPR20/10. In this work the absorbed dose standard has been commissioned in all the beams produced by the Elekta Synergy linac. Reference standard ionization chambers have been calibrated in terms of absorbed dose to graphite and this calibration has been converted to one in terms of absorbed dose to water. The results have been combined with the calibration in 60Co γ-rays to obtain measured values for the quality-dependent correction, kQ, for these reference standard chambers used in the Elekta beams. The resulting data are consistent with the interpolated kQ to within 0.4%, which is less than the combined standard uncertainty of kQ, 0.56%.

  9. Time-dependent radiation dose estimations during interplanetary space flights

    NASA Astrophysics Data System (ADS)

    Dobynde, M. I.; Shprits, Y.; Drozdov, A.

    2015-12-01

    Time-dependent radiation dose estimations during interplanetary space flights 1,2Dobynde M.I., 2,3Drozdov A.Y., 2,4Shprits Y.Y.1Skolkovo institute of science and technology, Moscow, Russia 2University of California Los Angeles, Los Angeles, USA 3Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, Russia4Massachusetts Institute of Technology, Cambridge, USASpace radiation is the main restriction for long-term interplanetary space missions. It induces degradation of external components and propagates inside providing damage to internal environment. Space radiation particles and induced secondary particle showers can lead to variety of damage to astronauts in short- and long- term perspective. Contribution of two main sources of space radiation- Sun and out-of-heliosphere space varies in time in opposite phase due to the solar activity state. Currently the only habituated mission is the international interplanetary station that flights on the low Earth orbit. Besides station shell astronauts are protected with the Earth magnetosphere- a natural shield that prevents significant damage for all humanity. Current progress in space exploration tends to lead humanity out of magnetosphere bounds. With the current study we make estimations of spacecraft parameters and astronauts damage for long-term interplanetary flights. Applying time dependent model of GCR spectra and data on SEP spectra we show the time dependence of the radiation in a human phantom inside the shielding capsule. We pay attention to the shielding capsule design, looking for an optimal geometry parameters and materials. Different types of particles affect differently on the human providing more or less harm to the tissues. Incident particles provide a large amount of secondary particles while propagating through the shielding capsule. We make an attempt to find an optimal combination of shielding capsule parameters, namely material and thickness, that will effectively decrease

  10. Comparison of the NMIJ and the ARPANSA standards for absorbed dose to water in high-energy photon beams.

    PubMed

    Shimizu, M; Morishita, Y; Kato, M; Tanaka, T; Kurosawa, T; Takata, N; Saito, N; Ramanathan, G; Harty, P D; Oliver, C; Wright, T; Butler, D J

    2015-04-01

    The authors report the results of an indirect comparison of the standards of absorbed dose to water in high-energy photon beams from a clinical linac and (60)Co radiation beam performed between the National Metrology Institute of Japan (NMIJ) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Three ionisation chambers were calibrated by the NMIJ in April and June 2013 and by the ARPANSA in May 2013. The average ratios of the calibration coefficients for the three ionisation chambers obtained by the NMIJ to those obtained by the ARPANSA were 0.9994, 1.0040 and 1.0045 for 6-, 10- and 15-MV (18 MV at the ARPANSA) high-energy photon beams, respectively. The relative standard uncertainty of the value was 7.2 × 10(-3). The ratio for (60)Co radiation was 0.9986(66), which is consistent with the results published in the key comparison of BIPM.RI(I)-K4.

  11. Tritons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-12-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons ((3)H(+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV.

  12. Helions at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-12-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent, for isotropic exposure of an adult male and an adult female to helions ((3)He(2+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Calculations were performed using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP), and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 2%. The greatest difference, 62%, occurred at 100 MeV.

  13. Absorbance correction method for estimation of telmisartan and metoprolol succinate in combined tablet dosage forms

    PubMed Central

    Patel, Komal; Patel, Amit; Dave, Jayant; Patel, Chaganbhai

    2012-01-01

    Aim and Background: The present manuscript describes simple, sensitive, rapid, accurate, precise and economical spectrophotometric method for the simultaneous determination of telmisartan and metoprolol succinate in combined tablet dosage form. Materials and Methods: The method is based on the absorbance correction equations for analysis of both the drugs using methanol as solvent. Telmisartan has absorbance maxima at 296 nm and metoprolol succinate has absorbance maxima at 223 nm in methanol. The linearity was obtained in the concentration range of 2-16 μg/ ml and 3-24 μg/ml for telmisartan and metoprolol succinate, respectively. The concentrations of the drugs were determined by using absorbance correction method at both the wavelengths. The method was successfully applied to pharmaceutical dosage form because no interference from the tablet excipients was found. The suitability of this method for the quantitative determination of telmisartan and metoprolol succinate was proved by validation. The proposed method was found to be simple and sensitive for the quality control application of telmisartan and metoprolol succinate in pharmaceutical dosage form. Result: The result of analysis has been validated statistically and by recovery studies. Recoveries were found in the range of 98.08-100.55% of telmisartan and 98.41-101.87% of metoprolol succinate. PMID:23781489

  14. Compartmental modeling of and radiation dose estimates for {sup 186}Re NR-LU-10 monoclonal antibody

    SciTech Connect

    Stubbs, J.B.; Beaumier, P.L.; Breitz, H.B.

    1994-05-01

    A clinical data set developed using {sup 186}Re labeled NR-LU-10, a pancarcinoma monoclonal antibody utilized for radioimmunotherapy, has been reanalyzed by compartmental modeling techniques. The pharmacokinetics and dosimetry estimates, derived from standard exponential curve filling, have been reported previously. In this work, we describe an 18-compartment model that integrates all measured biological data into a comprehensive biokinetic model. The model was developed with the SAAM (Simulation Analysis and Modeling) software. Residence times were calculated by integrating model-predicted time activity curves in tumor and 10 organs or tissues. Activity excreted via the hepatobiliary route was assumed to follow the ICRP 30 GI tract model, and a dynamic urinary bladder model (void interval = 4.8 hr) was used to simulate excretion via the urinary pathway. Dose estimates for 24 organs were calculated using the MIRD formalism. Tumor doses were estimated using absorbed fractions for electron sources uniformly distributed in small spheres. The model predicts that most activity is excreted (70% urine, 27% feces) by 300 hours post injection with the highest absorbed dose received by the excretory organs: lower large intestine (2.6 mGy/MBq), kidneys (1.4 mGy/MBq), upper large intestine (1.1 mGy/MBq). Tumor doses ranged from 180-1.8 mGy/MBq, depending on size (assuming tumor masses ranging from 1-100 grams). This multicompartmental model is comprehensive, provides conservation of activity, enables the modeling of hypothetical conditions (e.g., effect of plasma immunopheresis), and permits insight into the biological system.

  15. Estimation of Weapon Yield From Inversion of Dose Rate Contours

    DTIC Science & Technology

    2009-03-01

    Zucchini .................................................................................... 76 Operation PLUMBBOB—Priscilla...Appendix E: ESS FOM ....................................................................................................112 Appendix F: Zucchini FOM...Relationship of Dose Rate Contour Area, Weather Grid, and AOI ............... 57 23. Zucchini FDC, DNA-EX, and HPAC Dose Rate Contours at 28KT

  16. Determination of absorbed dose to water around a clinical HDR {sup 192}Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response

    SciTech Connect

    Carlsson Tedgren, Aasa; Elia, Rouba; Hedtjaern, Haakan; Olsson, Sara; Alm Carlsson, Gudrun

    2012-02-15

    Purpose: Experimental radiation dosimetry with thermoluminescent dosimeters (TLDs), calibrated in a {sup 60}Co or megavoltage (MV) photon beam, is recommended by AAPM TG-43U1for verification of Monte Carlo calculated absorbed doses around brachytherapy sources. However, it has been shown by Carlsson Tedgren et al.[Med. Phys. 38, 5539-5550 (2011)] that for TLDs of LiF:Mg,Ti, detector response was 4% higher in a {sup 137}Cs beam than in a {sup 60}Co one. The aim of this work was to investigate if similar over-response exists when measuring absorbed dose to water around {sup 192}Ir sources, using LiF:Mg,Ti dosimeters calibrated in a 6 MV photon beam. Methods: LiF dosimeters were calibrated to measure absorbed dose to water in a 6 MV photon beam and used to measure absorbed dose to water at distances of 3, 5, and 7 cm from a clinical high dose rate (HDR) {sup 192}Ir source in a polymethylmethacrylate (PMMA) phantom. Measured values were compared to values of absorbed dose to water calculated using a treatment planning system (TPS) including corrections for the difference in energy absorption properties between calibration quality and the quality in the users'{sup 192}Ir beam and for the use of a PMMA phantom instead of the water phantom underlying dose calculations in the TPS. Results: Measured absorbed doses to water around the {sup 192}Ir source were overestimated by 5% compared to those calculated by the TPS. Corresponding absorbed doses to water measured in a previous work with lithium formate electron paramagnetic resonance (EPR) dosimeters by Antonovic et al. [Med. Phys. 36, 2236-2247 (2009)], using the same irradiation setup and calibration procedure as in this work, were 2% lower than those calculated by the TPS. The results obtained in the measurements in this work and those obtained using the EPR lithium formate dosimeters were, within the expanded (k = 2) uncertainty, in agreement with the values derived by the TPS. The discrepancy between the results using

  17. Radioactivity levels of limestone and gypsum used as building raw materials in Turkey and estimation of exposure doses.

    PubMed

    Turhan, Seref

    2010-08-01

    The natural radionuclide contents of limestone and gypsum samples used as building raw materials in Turkey were measured by means of gamma spectrometer system with HPGe detector. The measured activity concentrations of (226)Ra, (232)Th and (40)K radionuclide were compared with the reported data from other countries. Radium equivalent activity and internal hazard index, absorbed gamma dose rate in indoor due to the external exposure and corresponding annual effective dose were determined to estimate the exposure risk arising due to the use of these raw materials. This study has shown that examined gypsum and limestone raw materials do not pose any excess radiological health problem and are safe for use in the construction of buildings.

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

    SciTech Connect

    Geneser, S; Paulsson, A; Sneed, P; Braunstein, S; Ma, L

    2015-06-15

    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 the 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.

  19. Estimation of effective doses to adult and pediatric patients from multislice computed tomography: A method based on energy imparted

    SciTech Connect

    Theocharopoulos, Nicholas; Damilakis, John; Perisinakis, Kostas; Tzedakis, Antonis; Karantanas, Apostolos; Gourtsoyiannis, Nicholas

    2006-10-15

    The purpose of this study is to provide a method and required data for the estimation of effective dose (E) values to adult and pediatric patients from computed tomography (CT) scans of the head, chest abdomen, and pelvis, performed on multi-slice scanners. Mean section radiation dose (d{sub m}) to cylindrical water phantoms of varying radius normalized over CT dose index free-in-air (CTDI{sub F}) were calculated for the head and body scanning modes of a multislice scanner with use of Monte Carlo techniques. Patients were modeled as equivalent water phantoms and the energy imparted ({epsilon}) to simulated pediatric and adult patients was calculated on the basis of measured CTDI{sub F} values. Body region specific energy imparted to effective dose conversion coefficients (E/{epsilon}) for adult male and female patients were generated from previous data. Effective doses to patients aged newborn to adult were derived for all available helical and axial beam collimations, taking into account age specific patient mass and scanning length. Depending on high voltage, body region, and patient sex, E/{epsilon} values ranged from 0.008 mSv/mJ for head scans to 0.024 mSv/mJ for chest scans. When scanned with the same technique factors as the adults, pediatric patients absorb as little as 5% of the energy imparted to adults, but corresponding effective dose values are up to a factor of 1.6 higher. On average, pediatric patients absorb 44% less energy per examination but have a 24% higher effective dose, compared with adults. In clinical practice, effective dose values to pediatric patients are 2.5 to 10 times lower than in adults due to the adaptation of tube current. A method is provided for the calculation of effective dose to adult and pediatric patients on the basis of individual patient characteristics such as sex, mass, dimensions, and density of imaged anatomy, and the technical features of modern multislice scanners. It allows the optimum selection of scanning

  20. Radiation Leukemogenesis: Applying Basic Science of Epidemiological Estimates of Low Dose Risks and Dose-Rate Effects

    SciTech Connect

    Hoel, D. G.

    1998-11-01

    The next stage of work has been to examine more closely the A-bomb leukemia data which provides the underpinnings of the risk estimation of CML in the above mentioned manuscript. The paper by Hoel and Li (Health Physics 75:241-50) shows how the linear-quadratic model has basic non-linearities at the low dose region for the leukemias including CML. Pierce et. al., (Radiation Research 123:275-84) have developed distributions for the uncertainty in the estimated exposures of the A-bomb cohort. Kellerer, et. al., (Radiation and Environmental Biophysics 36:73-83) has further considered possible errors in the estimated neutron values and with changing RBE values with dose and has hypothesized that the tumor response due to gamma may not be linear. We have incorporated his neutron model and have constricted new A-bomb doses based on his model adjustments. The Hoel and Li dose response analysis has also been applied using the Kellerer neutron dose adjustments for the leukemias. Finally, both Pierce's dose uncertainties and Kellerer neutron adjustments are combined as well as the varying RBE with dose as suggested by Rossi and Zaider and used for leukemia dose-response analysis. First the results of Hoel and Li showing a significantly improved fit of the linear-quadratic dose response by the inclusion of a threshold (i.e. low-dose nonlinearity) persisted. This work has been complete for both solid tumor as well as leukemia for both mortality as well as incidence data. The results are given in the manuscript described below which has been submitted to Health Physics.

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

    PubMed Central

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

    2016-01-01

    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 (hOrgan) 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 (CTDIvol)organ, convolution values that quantified the regional dose field for each organ. The organ dose was estimated by multiplying (CTDIvol)organ, convolution with the organ dose coefficients (hOrgan). 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

  2. 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

  3. Calorimetric determination of the absorbed dose to water for medium-energy x-rays with generating voltages from 70 to 280 kV.

    PubMed

    Krauss, A; Büermann, L; Kramer, H-M; Selbach, H-J

    2012-10-07

    For medium energy x-rays produced with tube voltages from 70 to 280 kV, the absorbed dose to water, D(w), has been determined by means of water calorimetry with relative standard uncertainties ranging from 0.45% to 0.98% at 280 and 70 kV. The results were confirmed by Monte Carlo calculations, in which the ratios of D(w) at 5 cm depth in a reference water phantom to the air kerma free in air, K(a), at the same point in space were compared to the corresponding ratios determined experimentally. The general agreement between measurement and calculation was better than 1%. These results confirm earlier investigations in which the absorbed dose to graphite was determined by means of a graphite extrapolation chamber. For the Monte Carlo calculations, an attempt was made to present a complete uncertainty budget, taking into account type B contributions also.

  4. Optimum combinations of visible and near-infrared reflectances for estimating the fraction of photosynthetically available radiation absorbed by plants

    NASA Technical Reports Server (NTRS)

    Podaire, Alain; Deschamps, Pierre-Yves; Frouin, R.; Asrar, Ghassem

    1991-01-01

    A useful parameter to estimate terrestrial primary productivity, that can be sensed from space, is the daily averaged fraction of Photosynthetically Available Radiation (PAR) absorbed by plants. To evaluate this parameter, investigators have relied on the fact that the relative amount of radiation reflected by a vegetated surface in the visible and near infrared depends on the fraction of the surface covered by the vegetation and therefore, correlates with absorbed PAR. They have used vegetation indices, namely normalized difference and simple ratio, to derive absorbed PAR. The problem with normalized difference and simple ratio is first, they are non linear functions of radiance or reflectance and therefore, cannot be readily applied to heterogeneous targets, second, they are used in generally nonlinear relationships, which make time integrals of the indices not proportional to primary productivity, and third, the relationships depend strongly on the type of canopy and background. To remove these limitations, linear combinations of visible and near infrared reflectances at optimum (one or two) viewing zenith angles are proposed.

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

    PubMed Central

    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. PMID:23591638

  6. Computer subroutines for the estimation of nuclear reaction effects in proton-tissue-dose calculations

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Khandelwal, G. S.

    1976-01-01

    Calculational methods for estimation of dose from external proton exposure of arbitrary convex bodies are briefly reviewed. All the necessary information for the estimation of dose in soft tissue is presented. Special emphasis is placed on retaining the effects of nuclear reaction, especially in relation to the dose equivalent. Computer subroutines to evaluate all of the relevant functions are discussed. Nuclear reaction contributions for standard space radiations are in most cases found to be significant. Many of the existing computer programs for estimating dose in which nuclear reaction effects are neglected can be readily converted to include nuclear reaction effects by use of the subroutines described herein.

  7. 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...

  8. 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...

  9. Depth absorbed dose and LET distributions of therapeutic {sup 1}H, {sup 4}He, {sup 7}Li, and {sup 12}C beams

    SciTech Connect

    Kempe, Johanna; Gudowska, Irena; Brahme, Anders

    2007-01-15

    The depth absorbed dose and LET (linear energy transfer) distribution of different ions of clinical interest such as {sup 1}H, {sup 4}He, {sup 7}Li, and {sup 12}C ions have been investigated using the Monte Carlo code SHIELD-HIT. The energies of the projectiles correspond to ranges in water and soft tissue of approximately 260 mm. The depth dose distributions of the primary particles and their secondaries have been calculated and separated with regard to their low and high LET components. A LET value below 10 eV/nm can generally be regarded as low LET and sparsely ionizing like electrons and photons. The high LET region may be assumed to start at 20 eV/nm where on average two double-strand breaks can be formed when crossing the periphery of a nucleosome, even though strictly speaking the LET limits are not sharp and ought to vary with the charge and mass of the ion. At the Bragg peak of a monoenergetic high energy proton beam, less than 3% of the total absorbed dose is comprised of high LET components above 20 eV/nm. The high LET contribution to the total absorbed dose in the Bragg peak is significantly larger with increasing ion charge as a natural result of higher stopping power and lower range straggling. The fact that the range straggling and multiple scattering are reduced by half from hydrogen to helium increases the possibility to accurately deposit only the high LET component in the tumor with negligible dose to organs at risk. Therefore, the lateral penumbra is significantly improved and the higher dose gradients of {sup 7}Li and {sup 12}C ions both longitudinally and laterally will be of major advantage in biological optimized radiation therapy. With increasing charge of the ion, the high LET absorbed dose in the beam entrance and the plateau regions where healthy normal tissues are generally located is also increased. The dose distribution of the high LET components in the {sup 7}Li beam is only located around the Bragg peak, characterized by a Gaussian

  10. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    NASA Astrophysics Data System (ADS)

    Shtejer, K.; Arruda-Neto, J. D. T.; Schulte, R.; Wroe, A.; Rodrigues, T. E.; de Menezes, M. O.; Moralles, M.; Guzmán, F.; Manso, M. V.

    2008-08-01

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, α3He to the total dose compared to the GEANT4 physical models chosen in this work.

  11. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    SciTech Connect

    Shtejer, K.; Arruda-Neto, J. D. T.; Rodrigues, T. E.; Schulte, R.; Wroe, A.; Menezes, M. O. de; Moralles, M.

    2008-08-11

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, {alpha}{sup 3}He to the total dose compared to the GEANT4 physical models chosen in this work.

  12. The LNE-LNHB water calorimeter for primary measurement of absorbed dose at low depth in water: application to medium-energy x-rays.

    PubMed

    Rapp, B; Perichon, N; Denoziere, M; Daures, J; Ostrowsky, A; Bordy, J-M

    2013-05-07

    Water calorimeters are used to establish absorbed dose standards in several national metrology laboratories involved in ionizing radiation dosimetry. These calorimeters have been first used in high-energy photons of (60)Co or accelerator beams, where the depth of measurement in water is large (5 or 10 cm). The LNE-LNHB laboratory has developed a specific calorimeter which makes measurements at low depth in water (down to 0.5 cm) easier, in order to fulfil the reference conditions required by the international dosimetry protocols for medium-energy x-rays. This new calorimeter was first used to measure the absorbed dose rate in water at a depth of 2 cm for six medium-energy x-ray reference beams with a tube potential from 80 to 300 kV. The relative combined standard uncertainty obtained on the absorbed dose rate to water is lower than 0.8%. An overview of the design of the calorimeter is given, followed by a detailed description of the calculation of the correction factors and the calorimetric measurements.

  13. Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

    SciTech Connect

    Power, S.; Mirza, M.; Thakorlal, A.; Ganai, B.; Gavagan, L. D.; Given, M. F.; Lee, M. J.

    2015-06-15

    PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

  14. Use of Monte Carlo simulations with a realistic rat phantom for examining the correlation between hematopoietic system response and red marrow absorbed dose in Brown Norway rats undergoing radionuclide therapy with {sup 177}Lu- and {sup 90}Y-BR96 mAbs

    SciTech Connect

    Larsson, Erik; Ljungberg, Michael; Martensson, Linda; Nilsson, Rune; Tennvall, Jan; Strand, Sven-Erik; Joensson, Bo-Anders

    2012-07-15

    weight, ranging from 225 g to 300 g, appeared to have no substantial effect for the estimated absorbed dose.

  15. Estimating scattered and absorbed radiation in plant canopies by remote sensing

    NASA Technical Reports Server (NTRS)

    Daughtry, G. S. T.; Ranson, K. J.

    1987-01-01

    Several research avenues are summarized. The relationships of canopy characteristics to multispectral reflectance factors of vegetation are reviewed. Several alternative approaches for incorporating spectrally derived information into plant models are discussed, using corn as the main example. A method is described and evaluated whereby a leaf area index is estimated from measurements of radiation transmitted through plant canopies, using soybeans as an example. Albedo of a big bluestem grass canopy is estimated from 60 directional reflectance factor measurements. Effects of estimating albedo with substantially smaller subsets of data are evaluated.

  16. SU-F-207-05: Excess Heat Corrections in a Prototype Calorimeter for Direct Realization of CT Absorbed Dose to Phantom

    SciTech Connect

    Chen-Mayer, H; Tosh, R

    2015-06-15

    Purpose: To reconcile air kerma and calorimetry measurements in a prototype calorimeter for obtaining absorbed dose in diagnostic CT beams. While corrections for thermal artifacts are routine and generally small in calorimetry of radiotherapy beams, large differences in relative stopping powers of calorimeter materials at the lower energies typical of CT beams greatly magnify their effects. Work-to-date on the problem attempts to reconcile laboratory measurements with modeling output from Monte Carlo and finite-element analysis of heat transfer. Methods: Small thermistor beads were embedded in a polystyrene (PS) core element of 1 cm diameter, which was inserted into a cylindrical HDPE phantom of 30 cm diameter and subjected to radiation in a diagnostic CT x-ray imaging system. Resistance changes in the thermistors due to radiation heating were monitored via lock-in amplifier. Multiple 3-second exposures were recorded at 8 different dose-rates from the CT system, and least-squares fits to experimental data were compared to an expected thermal response obtained by finite-element analysis incorporating source terms based on semi-empirical modeling and Monte Carlo simulation. Results: Experimental waveforms exhibited large thermal artifacts with fast time constants, associated with excess heat in wires and glass, and smaller steps attributable to radiation heating of the core material. Preliminary finite-element analysis follows the transient component of the signal qualitatively, but predicts a slower decay of temperature spikes. This was supplemented by non-linear least-squares fits incorporating semi-empirical formulae for heat transfer, which were used to obtain dose-to-PS in reasonable agreement with the output of Monte Carlo calculations that converts air kerma to absorbed dose. Conclusion: Discrepancies between the finite-element analysis and our experimental data testify to the very significant heat transfer correction required for absorbed dose calorimetry of

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

    PubMed Central

    Huang, Hongtai; Barzyk, Timothy M.

    2016-01-01

    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 impacts of EJ factors on dose-related variables. The purpose of this study is to identify quantitative approaches that incorporate conventional risk assessment (RA) dose modeling and cumulative risk assessment (CRA) considerations of disproportionate environmental exposure. We apply the Average Daily Dose (ADD) model, which has been commonly used in RA, to better understand impacts of EJ indicators upon exposure dose estimates and dose-related variables, termed the Environmental-Justice-Average-Daily-Dose (EJ-ADD) approach. On the U.S. nationwide census tract-level, we defined and quantified two EJ indicators (poverty and race/ethnicity) using an EJ scoring method to examine their relation to census tract-level multi-chemical exposure dose estimates. Pollutant doses for each tract were calculated using the ADD model, and EJ scores were assigned to each tract based on poverty- or race-related population percentages. Single- and multiple-chemical ADD values were matched to the tract-level EJ scores to analyze disproportionate dose relationships and contributing EJ factors. We found that when both EJ indicators were examined simultaneously, ADD for all pollutants generally increased with larger EJ scores. To demonstrate the utility of using EJ-ADD on the local scale, we approximated ADD levels of lead via soil/dust ingestion for simulated communities with different EJ-related scenarios. The local-level simulation indicates a substantial difference in exposure-dose levels between wealthy and EJ communities. The application of the EJ-ADD approach can link EJ factors to exposure dose estimate and identify potential EJ impacts on dose-related variables. PMID:28036053

  18. Evaluation of absorbed and effective doses to patients from radiopharmaceuticals using the ICRP 110 reference computational phantoms and ICRP 103 formulation.

    PubMed

    Hadid, Lama; Gardumi, Anna; Desbrée, Aurélie

    2013-09-01

    In diagnostic nuclear medicine, mean absorbed doses to patients' organs and effective doses are published for standard stylised anatomic models. To provide more realistic and detailed geometries of the human morphology, the International Commission on Radiological Protection (ICRP) has recently adopted male and female voxel phantoms to represent the reference adult. This work investigates the impact of the use of these new computational phantoms. The absorbed doses were calculated for 11 different radiopharmaceuticals currently used in diagnostic nuclear medicine. They were calculated for the ICRP 110 reference computational phantoms using the OEDIPE software and the MCNP extended Monte Carlo code. The biokinetic models were issued from ICRP Publications 53, 80 and 106. The results were then compared with published values given in these ICRP Publications. To discriminate the effect of anatomical differences on organ doses from the effect of the calculation method, the Monte Carlo calculations were repeated for the reference adult stylised phantom. The voxel effect, the influence of the use of different densities and nuclear decay data were also investigated. Effective doses were determined for the ICRP 110 adult reference computational phantom with the tissue weighting factor of ICRP Publication 60 and the tissue weighting factors of ICRP Publication 103. The calculation method and, in particular, the simulation of the electron transport have a significant influence on the calculated doses, especially, for small and walled organs. Overestimates of >200 % were observed for the urinary bladder wall of the stylised phantom compared with the computational phantoms. The unrealistic organ topology of the stylised phantom leads to important dose differences, sometimes by an order of magnitude. The effective doses calculated using the new computational phantoms and the new tissue weighting factors are globally lower than the published ones, except for some

  19. An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals.

    PubMed

    Andersson, M; Johansson, L; Minarik, D; Mattsson, S; Leide-Svegborn, S

    2014-12-01

    The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.

  20. RADIANCE: An automated, enterprise-wide solution for archiving and reporting CT radiation dose estimates.

    PubMed

    Cook, Tessa S; Zimmerman, Stefan L; Steingall, Scott R; Maidment, Andrew D A; Kim, Woojin; Boonn, William W

    2011-01-01

    There is growing interest in the ability to monitor, track, and report exposure to radiation from medical imaging. Historically, however, dose information has been stored on an image-based dose sheet, an arrangement that precludes widespread indexing. Although scanner manufacturers are beginning to include dose-related parameters in the Digital Imaging and Communications in Medicine (DICOM) headers of imaging studies, there remains a vast repository of retrospective computed tomographic (CT) data with image-based dose sheets. Consequently, it is difficult for imaging centers to monitor their dose estimates or participate in the American College of Radiology (ACR) Dose Index Registry. An automated extraction software pipeline known as Radiation Dose Intelligent Analytics for CT Examinations (RADIANCE) has been designed that quickly and accurately parses CT dose sheets to extract and archive dose-related parameters. Optical character recognition of information in the dose sheet leads to creation of a text file, which along with the DICOM study header is parsed to extract dose-related data. The data are then stored in a relational database that can be queried for dose monitoring and report creation. RADIANCE allows efficient dose analysis of CT examinations and more effective education of technologists, radiologists, and referring physicians regarding patient exposure to radiation at CT. RADIANCE also allows compliance with the ACR's dose reporting guidelines and greater awareness of patient radiation dose, ultimately resulting in improved patient care and treatment.

  1. 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

  2. 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.

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

    PubMed

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

    2010-07-01

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

  4. The biodistribution and dosimetry of {sup 117m}Sn DTPA with special emphasis on active marrow absorbed doses

    SciTech Connect

    Stubbs, J.; Atkins, H.

    1999-01-01

    {sup 117m}Sn(4+) DTPA is a new radiopharmaceutical for the palliation of pain associated with metastatic bone cancer. Recently, the Phase 2 clinical trials involving 47 patients were completed. These patients received administered activities in the range 6.7--10.6 MBq/kg of body mass. Frequent collections of urine were acquired over the first several hours postadministration and daily cumulative collections were obtained for the next 4--10 days. Anterior/posterior gamma camera images were obtained frequently over the initial 10 days. Radiation dose estimates were calculated for 8 of these patients. Each patient`s biodistribution data were mathematically simulated using a multicompartmental model. The model consisted of the following compartments: central, bone, kidney, other tissues, and cumulative urine. The measured cumulative urine data were used as references for the cumulative urine excretion compartment. The total-body compartment (sum of the bone surfaces, central, kidney, and other tissues compartments) was reference to all activity not excreted in the urine.

  5. MIRD pamphlet no. 16: Techniques for quantitative radiopharmaceutical biodistribution data acquisition and analysis for use in human radiation dose estimates.

    PubMed

    Siegel, J A; Thomas, S R; Stubbs, J B; Stabin, M G; Hays, M T; Koral, K F; Robertson, J S; Howell, R W; Wessels, B W; Fisher, D R; Weber, D A; Brill, A B

    1999-02-01

    This report describes recommended techniques for radiopharmaceutical biodistribution data acquisition and analysis in human subjects to estimate radiation absorbed dose using the Medical Internal Radiation Dose (MIRD) schema. The document has been prepared in a format to address two audiences: individuals with a primary interest in designing clinical trials who are not experts in dosimetry and individuals with extensive experience with dosimetry-based protocols and calculational methodology. For the first group, the general concepts involved in biodistribution data acquisition are presented, with guidance provided for the number of measurements (data points) required. For those with expertise in dosimetry, highlighted sections, examples and appendices have been included to provide calculational details, as well as references, for the techniques involved. This document is intended also to serve as a guide for the investigator in choosing the appropriate methodologies when acquiring and preparing product data for review by national regulatory agencies. The emphasis is on planar imaging techniques commonly available in most nuclear medicine departments and laboratories. The measurement of the biodistribution of radiopharmaceuticals is an important aspect in calculating absorbed dose from internally deposited radionuclides. Three phases are presented: data collection, data analysis and data processing. In the first phase, data collection, the identification of source regions, the determination of their appropriate temporal sampling and the acquisition of data are discussed. In the second phase, quantitative measurement techniques involving imaging by planar scintillation camera, SPECT and PET for the calculation of activity in source regions as a function of time are discussed. In addition, nonimaging measurement techniques, including external radiation monitoring, tissue-sample counting (blood and biopsy) and excreta counting are also considered. The third phase, data

  6. In vitro dissolution study of plutonium in aerosol particles from the Mayak PA: a tool for individualised dose estimates.

    PubMed

    Aladova, E E; Romanov, S A; Guilmette, R A; Khokhryakov, V F; Suslova, K G

    2007-01-01

    Chronic inhalation of Pu particles during Mayak processing is a potential concern for workers. Of the many particle properties that affect individualised dose estimates, particle solubility in lung fluids can be most important. This study compares in vitro dissolution rates of several plutonium industrial compounds present at different stages of the Mayak processing cycle using three different solvents. The results are then used to develop values of absorption parameters for individual dose assessments. In this study, the dissolution rates of nitrate, oxide and mixed plutonium aerosols were determined using a serum ultrafiltrate stimulant (SUF), phagolysosomal simulant fluid and Ringer's solution, all using a static system. According to the results obtained with SUF, Pu nitrate is absorbed into the blood to a larger extent than predicted using model parameters currently applied for Mayak workers. Absorption into the blood of 21.5 vs. 3% of deposited nuclide as current model predicts results in underestimation of systemic burden and overestimation of the lung dose. These data are being used to provide improved retrospective dose assessments for inhaled plutonium aerosols.

  7. Absorbed photosynthetically active radiation of steppe vegetation and sun-view geometry effects on APAR estimates

    NASA Technical Reports Server (NTRS)

    Walter-Shea, E. A.; Blad, B. L.; Mesarch, M. A.; Hays, C. J.; Deering, D. W.; Eck, T. F.

    1992-01-01

    Instantaneous fractions of absorbed photosynthetically active radiation (APAR) were measured at the Streletskaya Steppe Reserve in conjunction with canopy bidirectional-reflected radiation measured at solar zenith angles ranging between 37 and 74 deg during the Kursk experiment (KUREX-91). APAR values were higher for KUREX-91 than those for the first ISLSCP field experiment (FIFE-89) and the amount of APAR of a canopy was a function of solar zenith angle, decreasing as solar zenith angle increased at the resrve. Differences in absorption are attributed to leaf area index (LAI) and leaf angle distribution and subsequently transmitted radiation interactions. LAIs were considerably higher at the reserve than those at the FIFE site. Leaf angle distributions of the reserve approach a uniform distribution while distributions at the FIFE site more closely approximate erectophile distributions. Reflected photosynthetically active radiation (PAR) components at KUREX-91 and FIFE-89 were similar in magnitude and in their response to solar zenith angle. Transmitted PAR increased with increasing solar zenith angle at KUREX-91 and decreased with increasing solar zenith angle at FIFE-89. Transmitted PAR at FIFE-89 was considerably larger than those at KUREX-91.

  8. Integrated Codes for Estimating Environmental Accumulation and Individual Dose from Past Hanford Atmospheric Releases: Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Ikenberry, T. A.; Burnett, R. A.; Napier, B. A.; Reitz, N. A.; Shipler, D. B.

    1992-02-01

    Preliminary radiation doses were estimated and reported during Phase I of the Hanford Environmental Dose Reconstruction (HEDR) Project. As the project has progressed, additional information regarding the magnitude and timing of past radioactive releases has been developed, and the general scope of the required calculations has been enhanced. The overall HEDR computational model for computing doses attributable to atmospheric releases from Hanford Site operations is called HEDRIC (Hanford Environmental Dose Reconstruction Integrated Codes). It consists of four interrelated models: source term, atmospheric transport, environmental accumulation, and individual dose. The source term and atmospheric transport models are documented elsewhere. This report describes the initial implementation of the design specifications for the environmental accumulation model and computer code, called DESCARTES (Dynamic EStimates of Concentrations and Accumulated Radionuclides in Terrestrial Environments), and the individual dose model and computer code, called CIDER (Calculation of Individual Doses from Environmental Radionuclides). The computations required of these models and the design specifications for their codes were documented in Napier et al. (1992). Revisions to the original specifications and the basis for modeling decisions are explained. This report is not the final code documentation but gives the status of the model and code development to date. Final code documentation is scheduled to be completed in FY 1994 following additional code upgrades and refinements. The user's guide included in this report describes the operation of the environmental accumulation and individual dose codes and associated pre- and post-processor programs. A programmer's guide describes the logical structure of the programs and their input and output files.

  9. Age- and sex-dependent model for estimating radioiodine dose to a normal thyroid

    SciTech Connect

    Killough, G.G.; Eckerman, K.F.

    1985-01-01

    This paper describes the derivation of an age- and sex-dependent model of radioiodine dosimetry in the thyroid and the application of the model to estimating the thyroid dose for each of 4215 patients who were exposed to /sup 131/I in diagnostic and therapeutic procedures. The model was made to conform to these data requirements by the use of age-specific estimates of the biological half-time of iodine in the thyroid and an age- and sex-dependent representation of the mass of the thyroid. Also, it was assumed that the thyroid burden was maximum 24 hours after administration (the /sup 131/I dose is not critically sensitive to this assumption). The metabolic model is of the form A(t) = K(exp(-..mu../sub 1/t) - exp(-..mu../sub 2/t)) (..mu..Ci), where ..mu../sub 1/ = lambda/sub r/ + lambda/sub i//sup b/ (i = 1, 2), lambda/sub r/ is the radiological decay-rate coefficient, and lambda/sub i//sup b/ are biological removal rate coefficients. The values of lambda/sub i//sup b/ are determined by solving a nonlinear equation that depends on assumptions about the time of maximum uptake and the eventual biological loss rate (through which age dependence enters). The value of K may then be calculated from knowledge of the uptake at a particular time. The dosimetric S-factor (rad/..mu..Ci-day) is based on specific absorbed fractions for photons of energy ranging from 0.01 to 4.0 MeV for thyroid masses from 1.29 to 19.6 g; the functional form of the S-factor also involves the thyroid mass explicitly, through which the dependence on age and sex enters. An analysis of sensitivity of the model to uncertainties in the thyroid mass and the biological removal rate for several age groups is reported. The model could prove useful in the dosimetry of very short-lived radioiodines. Tables of age- and sex-dependent coefficients are provided to enable readers to make their own calculations. 12 refs., 5 figs., 4 tabs.

  10. Verification of absorbed dose determined with plane-parallel chambers in clinical electron beams following AAPM Task Group 39 protocol using ferrous sulphate dosimetry.

    PubMed

    Xu, Z; Li, H; Almond, P R; Guan, T Y

    1996-03-01

    The absorbed dose values determined with the Exradin and PTW-Markus plane-parallel chambers were compared to the values obtained with the ferrous sulphate dosimetry for a number of the Philips SL25 and the Therac 20 electron beams. For the plane-parallel chambers, the cavity-gas calibration factor Ngaspp, was derived by a direct comparison with a calibrated cylindrical chamber using the three different calibration methods as proposed by the newly published AAPM TG 39 protocol. For the ferrous sulphate dosimetry, an epsilon mG value of 352 x 10(-6) m-2 kg-1 Gy-1 was adopted from ICRU Report No. 35. The average ratio of the dose values determined with the plane-parallel chambers and the dose values determined with the Fricke dosimetry system was 1.001 +/- 1.4%. These measurements are consistent with the AAPM TG 39 protocol.

  11. Probability Estimates of Solar Proton Doses During Periods of Low Sunspot Number for Short Duration Missions

    NASA Technical Reports Server (NTRS)

    Atwell, William; Tylka, Allan J.; Dietrich, William F.; Rojdev, Kristina; Matzkind, Courtney

    2016-01-01

    In an earlier paper presented at ICES in 2015, we investigated solar particle event (SPE) radiation exposures (absorbed dose) to small, thinly-shielded spacecraft during a period when the monthly smoothed sunspot number (SSN) was less than 30. Although such months are generally considered "solar-quiet", SPEs observed during these months even include Ground Level Events, the most energetic type of SPE. In this paper, we add to previous study those SPEs that occurred in 1973-2015 when the SSN was greater than 30 but less than 50. Based on the observable energy range of the solar protons, we classify the event as GLEs, sub-GLEs, and sub-sub-GLEs, all of which are potential contributors to the radiation hazard. We use the spectra of these events to construct a probabilistic model of the absorbed dose due to solar protons when SSN < 50 at various confidence levels for various depths of shielding and for various mission durations. We provide plots and tables of solar proton-induced absorbed dose as functions of confidence level, shielding thickness, and mission-duration that will be useful to system designers.

  12. 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.

  13. Estimation of the collective dose in the Portuguese population due to medical procedures in 2010.

    PubMed

    Teles, Pedro; Carmen de Sousa, M; Paulo, Graciano; Santos, Joana; Pascoal, Ana; Cardoso, Gabriela; Lança, Isabel; Matela, Nuno; Janeiro, Luís; Sousa, Patrick; Carvoeiras, Pedro; Parafita, Rui; Santos, Ana Isabel; Simãozinho, Paula; Vaz, Pedro

    2013-05-01

    In a wide range of medical fields, technological advancements have led to an increase in the average collective dose in national populations worldwide. Periodic estimations of the average collective population dose due to medical exposure is, therefore of utmost importance, and is now mandatory in countries within the European Union (article 12 of EURATOM directive 97/43). Presented in this work is a report on the estimation of the collective dose in the Portuguese population due to nuclear medicine diagnostic procedures and the Top 20 diagnostic radiology examinations, which represent the 20 exams that contribute the most to the total collective dose in diagnostic radiology and interventional procedures in Europe. This work involved the collaboration of a multidisciplinary taskforce comprising representatives of all major Portuguese stakeholders (universities, research institutions, public and private healthcare providers, administrative services of the National Healthcare System, scientific and professional associations and private service providers). This allowed us to gather a comprehensive amount of data necessary for a robust estimation of the collective effective dose to the Portuguese population. The methodology used for data collection and dose estimation was based on European Commission recommendations, as this work was performed in the framework of the European wide Dose Datamed II project. This is the first study estimating the collective dose for the population in Portugal, considering such a wide national coverage and range of procedures and consisting of important baseline reference data. The taskforce intends to continue developing periodic collective dose estimations in the future. The estimated annual average effective dose for the Portuguese population was of 0.080±0.017 mSv caput(-1) for nuclear medicine exams and of 0.96±0.68 mSv caput(-1) for the Top 20 diagnostic radiology exams.

  14. Alpha particles at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, effective dose, and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.A.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-03-01

    Conversion coefficients have been calculated for fluence to absorbed dose, fluence to effective dose and fluence to gray equivalent, for isotropic exposure to alpha particles in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for effective dose are within 30 % of those calculated using ICRP 1990 recommendations.

  15. Fluence to absorbed dose, effective dose and gray equivalent conversion coefficients for iron nuclei from 10 MeV to 1 TeV, calculated using Monte Carlo radiation transport code MCNPX 2.7.A.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-03-01

    Conversion coefficients have been calculated for fluence-to-absorbed dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult male and an adult female to (56)Fe(26+) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). The coefficients were calculated using Monte Carlo transport code MCNPX 2.7.A and BodyBuilder 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Calculations using ICRP 2007 recommendations result in fluence-to-effective dose conversion coefficients that are almost identical at most energies to those calculated using ICRP 1990 recommendations.

  16. Effects of the loss of correlation structure on Phase 1 dose estimates. Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Simpson, J.C.

    1991-11-01

    In Phase I of the Hanford Environmental Dose Reconstruction Project, a step-by-step (modular) calculational structure was used. This structure was intended (1) to simplify the computational process, (2) to allow storage of intermediate calculations for later analyses, and (3) to guide the collection of data by presenting understandable structures for its use. The implementation of this modular structure resulted in the loss of correlation among inputs and outputs of the code, resulting in less accurate dose estimates than anticipated. The study documented in this report investigated two types of correlations in the Phase I model: temporal and pathway. Temporal correlations occur in the simulation when, in the calculation, data estimated for a previous time are used in a subsequent calculation. If the various portions of the calculation do not use the same realization of the earlier estimate, they are no longer correlated with respect to time. Similarly, spatial correlations occur in a simulation when, in the calculation, data estimated for a particular location are used in estimates for other locations. If the various calculations do not use the same value for the original location, they are no longer correlated with respect to location. The loss of the correlation structure in the Phase I code resulted in dose estimates that are biased. It is recommended that the air pathway dose model be restructured and the intermediate histograms eliminated. While the restructured code may still contain distinct modules, all input parameters to each module and all out put from each module should be retained in a database such that subsequent modules can access all the information necessary to retain the correlation structure.

  17. Evaluation of factors to convert absorbed dose calibrations from graphite to water for the NPL high-energy photon calibration service.

    PubMed

    Nutbrown, R F; Duane, S; Shipley, D R; Thomas, R A S

    2002-02-07

    The National Physical Laboratory (NPL) provides a high-energy photon calibration service using 4-19 MV x-rays and 60Co gamma-radiation for secondary standard dosemeters in terms of absorbed dose to water. The primary standard used for this service is a graphite calorimeter and so absorbed dose calibrations must be converted from graphite to water. The conversion factors currently in use were determined prior to the launch of this service in 1988. Since then, it has been found that the differences in inherent filtration between the NPL LINAC and typical clinical machines are large enough to affect absorbed dose calibrations and, since 1992, calibrations have been performed in heavily filtered qualities. The conversion factors for heavily filtered qualities were determined by interpolation and extrapolation of lightly filtered results as a function of tissue phantom ratio 20,10 (TPR20,10). This paper aims to evaluate these factors for all mega-voltage photon energies provided by the NPL LINAC for both lightly and heavily filtered qualities and for 60Co y-radiation in two ways. The first method involves the use of the photon fluence-scaling theorem. This states that if two blocks of different material are irradiated by the same photon beam, and if all dimensions are scaled in the inverse ratio of the electron densities of the two media, then, assuming that all photon interactions occur by Compton scatter the photon attenuation and scatter factors at corresponding scaled points of measurement in the phantom will be identical. The second method involves making in-phantom measurements of chamber response at a constant target-chamber distance. Monte Carlo techniques are then used to determine the corresponding dose to the medium in order to determine the chamber calibration factor directly. Values of the ratio of absorbed dose calibration factors in water and in graphite determined in these two ways agree with each other to within 0.2% (1sigma uncertainty). The best fit

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

  19. Dose estimation of animal experiments at the THOR BNCT beam by NCTPlan and Xplan.

    PubMed

    Liu, Yuan-Hao; Lee, Pei-Yi; Lin, Yu-Chuan; Chou, Fong-In; Chen, Wei-Lin; Huang, Yu-Shiang; Jiang, Shiang-Huei

    2014-06-01

    Dose estimation of animal experiments affects many subsequent derived quantities, such as RBE and CBE values. It is important to ensure the trustiness of calculated dose of the irradiated animals. However, the dose estimation was normally calculated using simplified geometries and tissue compositions, which led to rough results. This paper introduces the use of treatment planning systems NCTplan and Xplan for the dose estimation. A mouse was taken as an example and it was brought to hospital for micro-PET/CT scan. It was found that the critical organ doses of an irradiated mouse calculated by simplified model were unreliable in comparison to Xplan voxel model. The difference could reach the extent of several tenths percent. It is recommended that a treatment planning system should be introduced to future animal experiments to upgrade the data quality.

  20. The cytokinesis-blocked micronucleus assay: dose-response calibration curve, background frequency in the population and dose estimation.

    PubMed

    Rastkhah, E; Zakeri, F; Ghoranneviss, M; Rajabpour, M R; Farshidpour, M R; Mianji, F; Bayat, M

    2016-03-01

    An in vitro study of the dose responses of human peripheral blood lymphocytes was conducted with the aim of creating calibrated dose-response curves for biodosimetry measuring up to 4 Gy (0.25-4 Gy) of gamma radiation. The cytokinesis-blocked micronucleus (CBMN) assay was employed to obtain the frequencies of micronuclei (MN) per binucleated cell in blood samples from 16 healthy donors (eight males and eight females) in two age ranges of 20-34 and 35-50 years. The data were used to construct the calibration curves for men and women in two age groups, separately. An increase in micronuclei yield with the dose in a linear-quadratic way was observed in all groups. To verify the applicability of the constructed calibration curve, MN yields were measured in peripheral blood lymphocytes of two real overexposed subjects and three irradiated samples with unknown dose, and the results were compared with dose values obtained from measuring dicentric chromosomes. The comparison of the results obtained by the two techniques indicated a good agreement between dose estimates. The average baseline frequency of MN for the 130 healthy non-exposed donors (77 men and 55 women, 20-60 years old divided into four age groups) ranged from 6 to 21 micronuclei per 1000 binucleated cells. Baseline MN frequencies were higher for women and for the older age group. The results presented in this study point out that the CBMN assay is a reliable, easier and valuable alternative method for biological dosimetry.

  1. A Minute Dose of 14C-b-Carotene is Absorbed and Converted to Retinoids in Humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We dosed 8 adults with 14C-all-trans [10,10',11,11'-14C]-B-carotene (1.01 nmol) to quantify its absorption and metabolism. We used accelerator mass spectrometry (AMS) to measure 14C eliminated in feces over 14 days, in urine over 30 days, and that was retained in plasma over 166 days since dose. We...

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

    SciTech Connect

    Damilakis, John; Tzedakis, Antonis; Perisinakis, Kostas; Papadakis, Antonios E.

    2010-12-15

    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, simulating 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

  3. UNCERTAINTY ANALYSIS OF TCE USING THE DOSE EXPOSURE ESTIMATING MODEL (DEEM) IN ACSL

    EPA Science Inventory

    The ACSL-based Dose Exposure Estimating Model(DEEM) under development by EPA is used to perform art uncertainty analysis of a physiologically based pharmacokinetic (PSPK) model of trichloroethylene (TCE). This model involves several circulating metabolites such as trichloroacet...

  4. Anticipated Dose Estimate and Historical Documentation and Excel Files for Project W-460

    SciTech Connect

    LILLY, J.T.

    1999-12-07

    Document provides Excel Spreadsheets which form the basis for estimates of the expected whole body and extremity radiological dose to workers conducting planned plutonium stabilization and packaging operations at Hanford Plutonium Finishing Plant.

  5. Estimation of organ dose equivalents from residents of radiation-contaminated buildings with Rando phantom measurements.

    PubMed

    Lee, J S; Dong, S L; Wu, T H

    1999-05-01

    Since August 1996, a dose reconstruction model has been conducted with thermoluminescent dosimeter (TLD)-embedded chains, belts and badges for external dose measurements on the residents in radiation-contaminated buildings. The TLD dosimeters, worn on the front of the torso, would not be adequate for dose measurement in cases when the radiation is anisotropic or the incident angles of radiation sources are not directed in the front-to-back direction. The shielding and attenuation by the body would result in the dose equivalent estimation being somewhat skewed. An organ dose estimation method with a Rando phantom under various exposure geometries is proposed. The conversion factors, obtained from the phantom study, may be applicable to organ dose estimations for residents in the contaminated buildings if the incident angles correspond to the phantom simulation results. There is a great demand for developing a mathematical model or Monte Carlo calculation to deal with complicated indoor layout geometry problems involving ionizing radiation. Further research should be directed toward conducting laboratory simulation by investigating the relationship between doses delivered from multiple radiation sources. It is also necessary to collaborate with experimental biological dosimetry, such as chromosome aberration analysis, fluorescence in situ hybridization (FISH) and retrospective ESR-dosimetry with teeth, applied to the residents, so that the organ dose equivalent estimations may be more reliable for radio-epidemiological studies.

  6. Simplified estimation method for dose distributions around field junctions in proton craniospinal irradiation.

    PubMed

    Yamashita, Haruo; Kase, Yuki; Murayama, Shigeyuki

    2017-03-01

    In radiotherapy involving craniospinal irradiation (CSI), field junctions of therapeutic beams are necessary, because a CSI target is generally several times larger than the maximum field size of the beams. The purpose of this study was to develop a simplified method for estimating dose uniformity around the field junctions in proton CSI. We estimated the dose profiles around the field junctions of proton beams using a simplified field-junction model, in which partial lateral dose distributions around the field edge were assumed to be approximated using the error function. We measured the lateral dose distributions of the proton beams planned for the CSI treatment using a two-dimensional (2D) ionization chamber array. Although dose hot spots and cold spots tend to be underestimated by a chamber array because of the partial volume effect of the sensitive volume and discrete chamber positions, the model estimation results were fairly consistent with the measurements obtained using a 2D chamber array subjected to CSI-simulated serial irradiation. The simplified junction model enabled us to estimate the dose distributions and dependence of the setup position gap on the dose uniformity around the field junctions on the basis of the field-by-field dose profiles measured using the 2D chamber array.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  8. Dose estimation derived from the exposure to radon, thoron and their progeny in the indoor environment

    PubMed Central

    Ramola, R. C.; Prasad, Mukesh; Kandari, Tushar; Pant, Preeti; Bossew, Peter; Mishra, Rosaline; Tokonami, S.

    2016-01-01

    The annual exposure to indoor radon, thoron and their progeny imparts a major contribution to inhalation doses received by the public. In this study, we report results of time integrated passive measurements of indoor radon, thoron and their progeny concentrations that were carried out in Garhwal Himalaya with the aim of investigating significant health risk to the dwellers in the region. The measurements were performed using recently developed LR-115 detector based techniques. The experimentally determined values of radon, thoron and their progeny concentrations were used to estimate total annual inhalation dose and annual effective doses. The equilibrium factors for radon and thoron were also determined from the observed data. The estimated value of total annual inhalation dose was found to be 1.8 ± 0.7 mSv/y. The estimated values of the annual effective dose were found to be 1.2 ± 0.5 mSv/y and 0.5 ± 0.3 mSv/y, respectively. The estimated values of radiation doses suggest no important health risk due to exposure of radon, thoron and progeny in the study area. The contribution of indoor thoron and its progeny to total inhalation dose ranges between 13–52% with mean value of 30%. Thus thoron cannot be neglected when assessing radiation doses. PMID:27499492

  9. Dose estimation derived from the exposure to radon, thoron and their progeny in the indoor environment

    NASA Astrophysics Data System (ADS)

    Ramola, R. C.; Prasad, Mukesh; Kandari, Tushar; Pant, Preeti; Bossew, Peter; Mishra, Rosaline; Tokonami, S.

    2016-08-01

    The annual exposure to indoor radon, thoron and their progeny imparts a major contribution to inhalation doses received by the public. In this study, we report results of time integrated passive measurements of indoor radon, thoron and their progeny concentrations that were carried out in Garhwal Himalaya with the aim of investigating significant health risk to the dwellers in the region. The measurements were performed using recently developed LR-115 detector based techniques. The experimentally determined values of radon, thoron and their progeny concentrations were used to estimate total annual inhalation dose and annual effective doses. The equilibrium factors for radon and thoron were also determined from the observed data. The estimated value of total annual inhalation dose was found to be 1.8 ± 0.7 mSv/y. The estimated values of the annual effective dose were found to be 1.2 ± 0.5 mSv/y and 0.5 ± 0.3 mSv/y, respectively. The estimated values of radiation doses suggest no important health risk due to exposure of radon, thoron and progeny in the study area. The contribution of indoor thoron and its progeny to total inhalation dose ranges between 13–52% with mean value of 30%. Thus thoron cannot be neglected when assessing radiation doses.

  10. A new reference point for patient dose estimation in neurovascular interventional radiology.

    PubMed

    Kawasaki, Kohei; Imazeki, Masaharu; Hasegawa, Ryota; Shiba, Shinichi; Takahashi, Hiroyuki; Sato, Kazuhiko; Ota, Jyoji; Suzuki, Hiroaki; Awai, Kazuo; Sakamoto, Hajime; Tajima, Osamu; Tsukamoto, Atsuko; Kikuchi, Tatsuya; Kageyama, Takahiro; Kato, Kyoichi

    2013-07-01

    In interventional radiology, dose estimation using the interventional reference point (IRP) is a practical method for obtaining the real-time skin dose of a patient. However, the IRP is defined in terms of adult cardiovascular radiology and is not suitable for dosimetry of the head. In the present study, we defined a new reference point (neuro-IRP) for neuro-interventional procedures. The neuro-IRP was located on the central ray of the X-ray beam, 9 cm from the isocenter, toward the focal spot. To verify whether the neuro-IRP was accurate in dose estimation, we compared calculated doses at the neuro-IRP and actual measured doses at the surface of the head phantom for various directions of the X-ray projection. The resulting calculated doses were fairly consistent with actual measured doses, with the error in this estimation within approximately 15%. These data suggest that dose estimation using the neuro-IRP for the head is valid.

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

    PubMed

    Moriña, David; Grellier, James; Carnicer, Adela; Pernot, Eileen; Ryckx, Nick; Cardis, Elisabeth

    2016-09-01

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

  12. Determination of absorbed dose in water at the reference point d(r0, theta0) for an 192Ir HDR brachytherapy source using a Fricke system.

    PubMed

    Austerlitz, C; Mota, H C; Sempau, J; Benhabib, S M; Campos, D; Allison, R; DeAlmeida, C E; Zhu, D; Sibata, C H

    2008-12-01

    A ring-shaped Fricke device was developed to measure the absolute dose on the transverse bisector of a 192Ir high dose rate (HDR) source at 1 cm from its center in water, D(r0, theta0). It consists of a polymethylmethacrylate (PMMA) rod (axial axis) with a cylindrical cavity at its center to insert the 192Ir radioactive source. A ring cavity around the source with 1.5 mm thickness and 5 mm height is centered at 1 cm from the central axis of the source. This ring cavity is etched in a disk shaped base with 2.65 cm diameter and 0.90 cm thickness. The cavity has a wall around it 0.25 cm thick. This ring is filled with Fricke solution, sealed, and the whole assembly is immersed in water during irradiations. The device takes advantage of the cylindrical geometry to measure D(r0, theta0). Irradiations were performed with a Nucletron microselectron HDR unit loaded with an 192Ir Alpha Omega radioactive source. A Spectronic 1001 spectrophotometer was used to measure the optical absorbance using a 1 mL quartz cuvette with 1.00 cm light pathlength. The PENELOPE Monte Carlo code (MC) was utilized to simulate the Fricke device and the 192Ir Alpha Omega source in detail to calculate the perturbation introduced by the PMMA material. A NIST traceable calibrated well type ionization chamber was used to determine the air-kerma strength, and a published dose-rate constant was used to determine the dose rate at the reference point. The time to deliver 30.00 Gy to the reference point was calculated. This absorbed dose was then compared to the absorbed dose measured by the Fricke solution. Based on MC simulation, the PMMA of the Fricke device increases the D(r0, theta0) by 2.0%. Applying the corresponding correction factor, the D(r0, theta0) value assessed with the Fricke device agrees within 2.0% with the expected value with a total combined uncertainty of 3.43% (k=1). The Fricke device provides a promising method towards calibration of brachytherapy radiation sources in terms of D(r0

  13. Role of shielding in modulating the effects of solar particle events: Monte Carlo calculation of absorbed dose and DNA complex lesions in different organs

    NASA Technical Reports Server (NTRS)

    Ballarini, F.; Biaggi, M.; De Biaggi, L.; Ferrari, A.; Ottolenghi, A.; Panzarasa, A.; Paretzke, H. G.; Pelliccioni, M.; Sala, P.; Scannicchio, D.; Zankl, M.; Townsend, L. W. (Principal Investigator)

    2004-01-01

    Distributions of absorbed dose and DNA clustered damage yields in various organs and tissues following the October 1989 solar particle event (SPE) were calculated by coupling the FLUKA Monte Carlo transport code with two anthropomorphic phantoms (a mathematical model and a voxel model), with the main aim of quantifying the role of the shielding features in modulating organ doses. The phantoms, which were assumed to be in deep space, were inserted into a shielding box of variable thickness and material and were irradiated with the proton spectra of the October 1989 event. Average numbers of DNA lesions per cell in different organs were calculated by adopting a technique already tested in previous works, consisting of integrating into "condensed-history" Monte Carlo transport codes--such as FLUKA--yields of radiobiological damage, either calculated with "event-by-event" track structure simulations, or taken from experimental works available in the literature. More specifically, the yields of "Complex Lesions" (or "CL", defined and calculated as a clustered DNA damage in a previous work) per unit dose and DNA mass (CL Gy-1 Da-1) due to the various beam components, including those derived from nuclear interactions with the shielding and the human body, were integrated in FLUKA. This provided spatial distributions of CL/cell yields in different organs, as well as distributions of absorbed doses. The contributions of primary protons and secondary hadrons were calculated separately, and the simulations were repeated for values of Al shielding thickness ranging between 1 and 20 g/cm2. Slight differences were found between the two phantom types. Skin and eye lenses were found to receive larger doses with respect to internal organs; however, shielding was more effective for skin and lenses. Secondary particles arising from nuclear interactions were found to have a minor role, although their relative contribution was found to be larger for the Complex Lesions than for the

  14. Use of narrow-band spectra to estimate the fraction of absorbed photosynthetically active radiation

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G.; Huemmrich, Karl F.; Goward, Samuel N.

    1990-01-01

    A novel approach is proposed for using high-spectral resolution imagers to estimate the fraction of photosynthetically active radiation adsorbed, f(apar), by vegetated land surfaces. In comparison to approaches using broad-band vegetation indices, the proposed method appears to be relatively insensitive to the reflectance of nonphotosynthetically active material beneath the canopy, such as leaf litter or soil. The method is based on a relationship between the second derivative of the reflectance vs wavelength function for terrestrial vegetation and f(apar). The relationship can be defined by the second derivatives in either of two windows, one in the visible region centered at 0.69 micron, another in the near-infrared region centered at 0.74 micron.

  15. Sensitivity and uncertainty investigations for Hiroshima dose estimates and the applicability of the Little Boy mockup measurements

    SciTech Connect

    Bartine, D.E.; Cacuci, D.G.

    1983-09-13

    This paper describes sources of uncertainty in the data used for calculating dose estimates for the Hiroshima explosion and details a methodology for systematically obtaining best estimates and reduced uncertainties for the radiation doses received. (ACR)

  16. Decoloration and mineralization of reactive dyes using electron beam irradiation, Part I: Effect of the dye structure, concentration and absorbed dose (single, binary and ternary systems)

    NASA Astrophysics Data System (ADS)

    Vahdat, Ali; Bahrami, S. Hajir; Arami, M.; Bahjat, A.; Tabakh, F.; Khairkhah, M.

    2012-07-01

    In this study, three different reactive dyes (C.I. Reactive Red 4, C.I. Reactive Blue 2 and C.I. Reactive Yellow 4) and their blend solutions were irradiated with 10 MeV electron beam. Effect of absorbed dose, dye structure and primary solution concentrations on the pH value changes, degree of decoloration and chemical oxygen demand (COD) removal of solutions were investigated. Results show that this method is effective in decomposition and decoloration of the dyes solutions. This method can be applied in mineralization of wastewater containing different dyes.

  17. Update on the Code Intercomparison and Benchmark for Muon Fluence and Absorbed Dose Induced by an 18 GeV Electron Beam After Massive Iron Shielding

    SciTech Connect

    Fasso, A.; Ferrari, A.; Ferrari, A.; Mokhov, N. V.; Mueller, S. E.; Nelson, W. R.; Roesler, S.; Sanami, t.; Striganov, S. I.; Versaci, R.

    2016-12-01

    In 1974, Nelson, Kase and Svensson published an experimental investigation on muon shielding around SLAC high-energy electron accelerators [1]. They measured muon fluence and absorbed dose induced by 14 and 18 GeV electron beams hitting a copper/water beamdump and attenuated in a thick steel shielding. In their paper, they compared the results with the theoretical models available at that time. In order to compare their experimental results with present model calculations, we use the modern transport Monte Carlo codes MARS15, FLUKA2011 and GEANT4 to model the experimental setup and run simulations. The results are then compared between the codes, and with the SLAC data.

  18. 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.

  19. Evaluation of the accuracy of fetal dose estimates using TG-36 data

    SciTech Connect

    Kry, Stephen F.; Starkschall, George; Antolak, John A.; Salehpour, Mohammad

    2007-04-15

    The American Association of Physicists in Medicine Radiation Therapy Committee Task Group 36 report (TG-36) provides guidelines for managing radiation therapy of pregnant patients. Included in the report are data that can be used to estimate the dose to the fetus. The purpose of this study is to evaluate the accuracy of these fetal dose estimates as compared to clinically measured values. TG-36 calculations were performed and compared with measurements of the fetal dose made in vivo or in appropriately-designed phantoms. Calculation and measurement data was collected for eight pregnant patients who underwent radiation therapy at the MD Anderson Cancer Center as well as for several fetal dose studies in the literature. The maximum measured unshielded fetal dose was 47 cGy, which was 1.5% of the prescription dose. For all cases, TG-36 calculations and measured fetal doses differed by up to a factor of 3--the ratio of the calculated to measured dose ranged from 0.34 to 2.93. On average, TG-36 calculations underestimated the measured dose by 31%. No significant trends in the relationship between the calculated and measured fetal doses were found based on the distance from, or the size of, the treatment field.

  20. Slide Rule for Rapid Response Estimation of Radiological Dose from Criticality Accidents

    SciTech Connect

    Broadhead, B L; Childs, R L; Hopper, C M; Parks, C V

    1999-09-20

    This paper describes a functional slide rule that provides a readily usable "in-hand" method for estimating nuclear criticality accident information from sliding graphs, thereby permitting (1) the rapid estimation of pertinent criticality accident information without laborious or sophisticated calculations in a nuclear criticality emergency situation, (2) the appraisal of potential fission yields and external personnel radiation exposures for facility safety analyses, and (3) a technical basis for emergency preparedness and training programs at nonreactor nuclear facilities. The slide rule permits the estimation of neutron and gamma dose rates and integrated doses based upon estimated fission yields, distance from the fission source, and time-after criticality accidents for five different critical systems. Another sliding graph permits the estimation of critical solution fission yields based upon fissile material concentration, critical vessel geometry, and solution addition rate. Another graph provides neutron and gamma dose-reduction factors for water, steel, and concrete shields.

  1. Role of cardiac ultrafast cameras with CZT solid-state detectors and software developments on radiation absorbed dose reduction to the patients.

    PubMed

    Gunalp, Bengul

    2015-07-01

    Myocardial perfusion imaging (MPI) is one the most contributing nuclear medicine technique to the annual population dose. The purpose of this study is to compare radiation-absorbed doses to the patients examined by conventional cardiac SPECT (CSPECT) camera and ultrafast cardiac (UFC) camera with cadmium-zinc-telluride (CZT) solid-state detectors. Total injected activity was reduced by 50 % when both stress and rest images were acquired and by 75 % when only stress images were taken with UFC camera. As a result of this, the mean total effective dose was found significantly lower with UFC camera (2.2 ± 1.2 mSv) than CSPECT (7.7 ± 3.8 mSv) (p < 0.001). Further dose reduction was obtained by reducing equivocal test results and unnecessary additional examinations with UFC camera. Using UFC camera, MPI can be conveniently used for the detection of coronary artery disease (CAD) much less increasing annual population radiation dose as it had been before.

  2. Non-parametric estimators of a monotonic dose-response curve and bootstrap confidence intervals.

    PubMed

    Dilleen, Maria; Heimann, Günter; Hirsch, Ian

    2003-03-30

    In this paper we consider study designs which include a placebo and an active control group as well as several dose groups of a new drug. A monotonically increasing dose-response function is assumed, and the objective is to estimate a dose with equivalent response to the active control group, including a confidence interval for this dose. We present different non-parametric methods to estimate the monotonic dose-response curve. These are derived from the isotonic regression estimator, a non-negative least squares estimator, and a bias adjusted non-negative least squares estimator using linear interpolation. The different confidence intervals are based upon an approach described by Korn, and upon two different bootstrap approaches. One of these bootstrap approaches is standard, and the second ensures that resampling is done from empiric distributions which comply with the order restrictions imposed. In our simulations we did not find any differences between the two bootstrap methods, and both clearly outperform Korn's confidence intervals. The non-negative least squares estimator yields biased results for moderate sample sizes. The bias adjustment for this estimator works well, even for small and moderate sample sizes, and surprisingly outperforms the isotonic regression method in certain situations.

  3. Comparison of Radiation Dose Estimation for Myeloablative Radioimmunotherapy for Relapsed or Recurrent Mantle Cell Lymphoma using 131I Tositumomab to that of Other Types of Non-Hodgkin's Lymphoma

    SciTech Connect

    Rajendran, Joseph G.; Gopal, Ajay K.; Durack, Larry; Fisher, Darrell R.; Press, Oliver W.; Eary, Janet F.

    2004-12-01

    Patients with relapsed or refractory mantle cell lymphoma (MCL) demonstrate poor survival after standard treatment. Myeloablative radioimmunotherapy (RIT) using 131I tositumomab (anti-CD20) has the ability to deliver specific radiation absorbed dose to antigen bearing tumor. We reviewed normal organ radiation absorbed doses in MCL patients. METHODS: Records of patients with MCL (n = 25), who received myeloablative RIT between January 1996 and December 2003 were reviewed. Individual patient radiation dosimetry was performed on all patients after a trace labeled infusion of 131I tositumomab (mean = 348 MBq), to calculate the required amount of radioactivity for therapy, based on MIRD schema. RESULTS: Mean organ residence times (hr) corrected for CT derived organ volumes for MCL, were as follows: Lungs:9.0; Liver:12.4; Kidneys:1.7; Spleen:2.17; Whole Body:62.4 and mean radiation absorbed doses mGy/Mbq were: Lungs:1.2; Liver:1.1; Kidneys:0.85; Spleen:1.7; Whole Body: 0.21. This is similar to patients with other NHL. Patients received a mean activity of 21 GBq of 131I (range = 11.5 - 41.4) for therapy estimated to deliver 25 Gy to the normal organ receiving the highest radiation absorbed dose. CONCLUSION: Myeloablative RIT using 131I tositumomab results in normal organ radiation absorbed doses similar to those in patients with other non-Hodgkin's lymphoma, and is suitable for treating patients with relapsed or refractory MCL.

  4. Dose estimation for internal organs during boron neutron capture therapy for body-trunk tumors.

    PubMed

    Sakurai, Y; Tanaka, H; Suzuki, M; Masunaga, S; Kinashi, Y; Kondo, N; Ono, K; Maruhashi, A

    2014-06-01

    Radiation doses during boron neutron capture therapy for body-trunk tumors were estimated for various internal organs, using data from patients treated at Kyoto University Research Reactor Institute. Dose-volume histograms were constructed for tissues of the lung, liver, kidney, pancreas, and bowel. For pleural mesothelioma, the target total dose to the normal lung tissues on the diseased side is 5Gy-Eq in average for the whole lung. It was confirmed that the dose to the liver should be carefully considered in cases of right lung disease.

  5. 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

  6. A strategy to model nonmonotonic dose-response curve and estimate IC50.

    PubMed

    Zhang, Hui; Holden-Wiltse, Jeanne; Wang, Jiong; Liang, Hua

    2013-01-01

    The half-maximal inhibitory concentration IC[Formula: see text] is an important pharmacodynamic index of drug effectiveness. To estimate this value, the dose response relationship needs to be established, which is generally achieved by fitting monotonic sigmoidal models. However, recent studies on Human Immunodeficiency Virus (HIV) mutants developing resistance to antiviral drugs show that the dose response curve may not be monotonic. Traditional models can fail for nonmonotonic data and ignore observations that may be of biologic significance. Therefore, we propose a nonparametric model to describe the dose response relationship and fit the curve using local polynomial regression. The nonparametric approach is shown to be promising especially for estimating the IC[Formula: see text] of some HIV inhibitory drugs, in which there is a dose-dependent stimulation of response for mutant strains. This model strategy may be applicable to general pharmacologic, toxicologic, or other biomedical data that exhibits a nonmonotonic dose response relationship for which traditional parametric models fail.

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

    SciTech Connect

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

    1993-07-01

    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. The 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.

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

    SciTech Connect

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

    1993-03-01

    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. The 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.

  9. Estimate of Dose and Residual Activity in the SNS Ring Collimation Straight

    NASA Astrophysics Data System (ADS)

    Ludewig, H.; Simos, N.; Davino, D.; Cousineau, S.; Catalan-Lasheras, N.; Brodowski, J.; Tuozzolo, J.; Longo, C.; Mullany, B.; Raparia, D.

    2003-12-01

    The collimation system in the SNS ring includes a two-stage collimator consisting of a halo scraper and an appropriate fixed aperture collimator. This unit is placed between the first quadru-pole and the first doublet in the collimation straight section of the ring. The entire structure is surrounded by an outer shield structure. The downstream dose to the doublet and the attached corrector magnet will be estimated for normal operating conditions. In addition, the activities of cooling water, tunnel air, and dose to cables will be estimated. The dose at the flange locations will be estimated following machine shutdown. Finally, the implied dose to surroundings during the removal of an exposed collimator will be made.

  10. Estimating the predictive quality of dose-response after model selection.

    PubMed

    Hu, Chuanpu; Dong, Yingwen

    2007-07-20

    Prediction of dose-response is important in dose selection in drug development. As the true dose-response shape is generally unknown, model selection is frequently used, and predictions based on the final selected model. Correctly assessing the quality of the predictions requires accounting for the uncertainties caused by the model selection process, which has been difficult. Recently, a new approach called data perturbation has emerged. It allows important predictive characteristics be computed while taking model selection into consideration. We study, through simulation, the performance of data perturbation in estimating standard error of parameter estimates and prediction errors. Data perturbation was found to give excellent prediction error estimates, although at times large Monte Carlo sizes were needed to obtain good standard error estimates. Overall, it is a useful tool to characterize uncertainties in dose-response predictions, with the potential of allowing more accurate dose selection in drug development. We also look at the influence of model selection on estimation bias. This leads to insights into candidate model choices that enable good dose-response prediction.

  11. Efficacy and immunogenicity of single-dose AdVAV intranasal anthrax vaccine compared to anthrax vaccine absorbed in an aerosolized spore rabbit challenge model.

    PubMed

    Krishnan, Vyjayanthi; Andersen, Bo H; Shoemaker, Christine; Sivko, Gloria S; Tordoff, Kevin P; Stark, Gregory V; Zhang, Jianfeng; Feng, Tsungwei; Duchars, Matthew; Roberts, M Scot

    2015-04-01

    AdVAV is a replication-deficient adenovirus type 5-vectored vaccine expressing the 83-kDa protective antigen (PA83) from Bacillus anthracis that is being developed for the prevention of disease caused by inhalation of aerosolized B. anthracis spores. A noninferiority study comparing the efficacy of AdVAV to the currently licensed Anthrax Vaccine Absorbed (AVA; BioThrax) was performed in New Zealand White rabbits using postchallenge survival as the study endpoint (20% noninferiority margin for survival). Three groups of 32 rabbits were vaccinated with a single intranasal dose of AdVAV (7.5 × 10(7), 1.5 × 10(9), or 3.5 × 10(10) viral particles). Three additional groups of 32 animals received two doses of either intranasal AdVAV (3.5 × 10(10) viral particles) or intramuscular AVA (diluted 1:16 or 1:64) 28 days apart. The placebo group of 16 rabbits received a single intranasal dose of AdVAV formulation buffer. All animals were challenged via the inhalation route with a targeted dose of 200 times the 50% lethal dose (LD50) of aerosolized B. anthracis Ames spores 70 days after the initial vaccination and were followed for 3 weeks. PA83 immunogenicity was evaluated by validated toxin neutralizing antibody and serum anti-PA83 IgG enzyme-linked immunosorbent assays (ELISAs). All animals in the placebo cohort died from the challenge. Three of the four AdVAV dose cohorts tested, including two single-dose cohorts, achieved statistical noninferiority relative to the AVA comparator group, with survival rates between 97% and 100%. Vaccination with AdVAV also produced antibody titers with earlier onset and greater persistence than vaccination with AVA.

  12. A Novel Method of Estimating Dose Responses for Polymer Gels Using Texture Analysis of Scanning Electron Microscopy Images

    PubMed Central

    Shih, Cheng-Ting; Hsu, Jui-Ting; Han, Rou-Ping; Hsieh, Bor-Tsung; Chang, Shu-Jun; Wu, Jay

    2013-01-01

    Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM) images. The modified N-isopropyl-acrylamide (NIPAM) gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM). The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R2 value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were −7.60%, 5.80%, 2.53%, and −0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection. PMID:23843998

  13. A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

    PubMed

    Shih, Cheng-Ting; Hsu, Jui-Ting; Han, Rou-Ping; Hsieh, Bor-Tsung; Chang, Shu-Jun; Wu, Jay

    2013-01-01

    Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM) images. The modified N-isopropyl-acrylamide (NIPAM) gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM). The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2) value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

  14. TU-F-CAMPUS-T-05: Replacement Computational Phantoms to Estimate Dose in Out-Of-Field Organs and Tissues

    SciTech Connect

    Gallagher, K; Tannous, J; Nabha, R; Feghali, J; Ayoub, Z; Jalbout, W; Youssef, B; Taddei, P

    2015-06-15

    Purpose: To estimate the absorbed dose in organs and tissues at risk for radiogenic cancer for children receiving photon radiotherapy for localized brain tumors (LBTs) by supplementing their missing body anatomies with those of replacement computational phantoms. Applied beyond the extent of the RT Images collected by computed tomography simulation, these phantoms included RT Image and RT Structure Set objects that encompassed sufficient extents and contours for dosimetric calculations. Method: Nine children, aged 2 to 14 years, who received three-dimensional conformal radiotherapy for low-grade LBTs, were randomly selected for this study under Institutional-Review-Board protocol. Because the extents of their RT Images were cranial only, they were matched for size and sex with patients from a previous study with larger extents and for whom contours of organs at risk for radiogenic cancer had already been delineated. Rigid fusion was performed between the patients’ data and those of the replacement computational phantoms using commercial software. In-field dose was calculated with a clinically-commissioned treatment planning system, and out-of-field dose was estimated with an analytical model. Results: Averaged over all nine children and normalized for a therapeutic dose of 54 Gy prescribed to the PTV, where the PTV is the GTV, the highest mean organ doses were 3.27, 2.41, 1.07, 1.02, 0.24, and 0.24 Gy in the non-tumor remainder, red bone marrow, thyroid, skin, breasts, and lungs, respectively. The mean organ doses ranged by a factor of 3 between the smallest and largest children. Conclusion: For children receiving photon radiotherapy for LBTs, we found their doses in organs at risk for second cancer to be non-negligible, especially in the non-tumor remainder, red bone marrow, thyroid, skin, breasts, and lungs. This study demonstrated the feasibility for patient dosimetry studies to augment missing patient anatomy by applying size- and sex-matched replacement

  15. 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.

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

    SciTech Connect

    Alva-Sánchez, Héctor

    2014-11-07

    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.

  17. Estimation of radionuclide ingestion: Lessons from dose reconstruction for fallout from the Nevada Test Site

    SciTech Connect

    Breshears, D.D.; Whicker, F.W.; Kirchner, T.B.; Anspaugh, L.R.

    1994-09-01

    The United States conducted atmospheric testing of nuclear devices at the Nevada Test Site from 1951 through 1963. In 1979 the U.S. Department of Energy established the Off-Site Radiation Exposure Review Project to compile a data base related to health effects from nuclear testing and to reconstruct doses to public residing off of the Nevada Test Site. This project is the most comprehensive dose reconstruction project to date, and, since similar assessments are currently underway at several other locations within and outside the U.S., lessons from ORERP can be valuable. A major component of dose reconstruction is estimation of dose from radionuclide ingestion. The PATHWAY food-chain model was developed to estimate the amount of radionuclides ingested. For agricultural components of the human diet, PATHWAY predicts radionuclide concentrations and quantities ingested. To improve accuracy and model credibility, four components of model analysis were conducted: estimation of uncertainty in model predictions, estimation of sensitivity of model predictions to input parameters, and testing of model predictions against independent data (validation), and comparing predictions from PATHWAY with those from other models. These results identified strengths and weaknesses in the model and aided in establishing the confidence associated with model prediction, which is a critical component risk assessment and dose reconstruction. For fallout from the Nevada Test Site, by far, the largest internal doses were received by the thyroid. However, the predicted number of fatal cancers from ingestion dose was generally much smaller than the number predicted from external dose. The number of fatal cancers predicted from ingestion dose was also orders of magnitude below the normal projected cancer rate. Several lessons were learned during the study that are relevant to other dose reconstruction efforts.

  18. A method for estimating occupational radiation dose to individuals, using weekly dosimetry data

    SciTech Connect

    Mitchell, T.J.; Ostrouchov, G.; Frome, E.L.; Kerr, G.D.

    1993-12-01

    Statistical analyses of data from epidemiologic studies of workers exposed to radiation have been based on recorded annual radiation doses. It is usually assumed that the annual dose values are known exactly, although it is generally recognized that the data contain uncertainty due to measurement error and bias. We propose the use of a probability distribution to describe an individual`s dose during a specific period of time. Statistical methods for estimating this dose distribution are developed. The methods take into account the ``measurement error`` that is produced by the dosimetry system, and the bias that was introduced by policies that lead to right censoring of small doses as zero. The method is applied to a sample of dose histories obtained from hard copy dosimetry records at Oak Ridge National Laboratory (ORNL). The result of this evaluation raises serious questions about the validity of the historical personnel dosimetry data that is currently being used in low-dose studies of nuclear industry workers. In particular, it appears that there was a systematic underestimation of doses for ORNL workers. This could result in biased estimates of dose-response coefficients and their standard errors.

  19. 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...

  20. Occurrence of UV-Absorbing, Mycosporine-Like Compounds among Cyanobacterial Isolates and an Estimate of Their Screening Capacity

    PubMed Central

    Garcia-Pichel, Ferran; Castenholz, Richard W.

    1993-01-01

    A survey of 20 strains of cyanobacteria (belonging to 13 genera) isolated from habitats exposed to strong insolation revealed that 13 strains contained one or more water-soluble, UV-absorbing, mycosporine amino acid (MAA)-like compounds. Some of the compounds were identical in several strains. In all, 13 distinct compounds were found. The UV absorption spectra of MAAs complemented well that of the extracellular sunscreen pigment scytonemin, which many of the strains also produced. Even though the specific MAA contents were variable among strains, they were invariably higher when the cultures were grown with UV radiation than when it was absent. In five strains tested, the MAA complement accumulated as a solute in the cytoplasmic cell fraction. The sunscreen capacities of MAA and scytonemin and their combined capacity were estimated for each strain and condition on the basis of the specific contents, cell size, and cellular location of the compounds. The estimates suggested that significant, albeit not complete, protection from UV photodamage could be gained from the possession of either MAA or scytonemin but especially from simultaneous screening by both types of compounds. PMID:16348839

  1. Absorbed dose assessment of 177Lu-zoledronate and 177Lu-EDTMP for human based on biodistribution data in rats

    PubMed Central

    Yousefnia, Hassan; Zolghadri, Samaneh; Jalilian, Amir Reza

    2015-01-01

    Over the past few decades, several bone-seeking radiopharmaceuticals including various bisphosphonate ligands and β-emitting radionuclides have been developed for bone pain palliation. Recently, 177Lu was successfully labeled with zoledronic acid (177Lu-ZLD) as a new generation potential bisphosphonate and demonstrated significant accumulation in bone tissue. In this work, the absorbed dose to each organ of human for 177Lu-ZLD and 177Lu-ethylenediaminetetramethylene phosphonic acid (177Lu-EDTMP;as the only clinically bone pain palliation agent) was investigated based on biodistribution data in rats by medical internal radiation dosimetry (MIRD) method. 177Lu-ZLD and 177Lu-EDTMP were prepared in high radiochemical purity (>99%, instant thin layer chromatography (ITLC)) at the optimized condition. The biodistribution of the complexes demonstrated fast blood clearance and major accumulation in the bone tissue. The highest absorbed dose for both 177Lu-ZLD and 177Lu-EDTMP is observed in trabecular bone surface with 12.173 and 10.019 mSv/MBq, respectively. The results showed that 177Lu-ZLD has better characteristics compared to 177Lu-EDTMP and can be a good candidate for bone pain palliation. PMID:26170557

  2. Comparison of the calculated absorbed dose using the Cadplan™ treatment planning software and Tld-100 measurements in an Alderson-Rando phantom for a bronchogenic treatment

    SciTech Connect

    Gutiérrez Castillo, J. G.; Álvarez Romero, J. T. E-mail: fisarmandotorres@gmail.com Calderón, A. Torres E-mail: fisarmandotorres@gmail.com M, V. Tovar E-mail: fisarmandotorres@gmail.com

    2014-11-07

    To verify the accuracy of the absorbed doses D calculated by a TPS Cadplan for a bronchogenic treatment (in an Alderson-Rando phantom) are chosen ten points with the following D's and localizations. Point 1, posterior position on the left edge with 136.4 Gy. Points: 2, 3 and 4 in the left lung with 104.9, 104.3 and 105.8 Gy, respectively; points 5 and 6 at the mediastinum with 192.4 and 173.5 Gy; points 7, 8 and 9 in the right lung with 105.8, 104.2 and 104.7 Gy, and 10 at posterior position on right edge with 143.7 Gy. IAEA type capsules with TLD 100 powder are placed, planned and irradiated. The evaluation of the absorbed dose is carried out a curve of calibration for the LiF response (nC) {sup vs} {sup DW}, to several cavity theories. The traceability for the DW is obtained with a secondary standard calibrated at the NRC (Canada). The dosimetric properties for the materials considered are determined from the Hounsfield numbers reported by the TPS. The stopping power ratios are calculated for nominal spectrum to 6 MV photons. The percent variations among the planned and determined D in all the cases they are < ± 3%.

  3. Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the PTB, Germany and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D. T.; Kapsch, R.-P.; Krauss, A.

    2016-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Physikalisch-Technische Bundesanstalt, (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in October 2015. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the PTB and the BIPM standards for absorbed dose to water, is 0.9977 with a combined standard uncertainty of 3.8 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  4. Structural changes caused by radiation-induced reduction and radiolysis: the effect of X-ray absorbed dose in a fungal multicopper oxidase.

    PubMed

    De la Mora, Eugenio; Lovett, Janet E; Blanford, Christopher F; Garman, Elspeth F; Valderrama, Brenda; Rudino-Pinera, Enrique

    2012-05-01

    X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O(2). In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UV-Vis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O(2) reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account.

  5. Structural changes caused by radiation-induced reduction and radiolysis: the effect of X-ray absorbed dose in a fungal multicopper oxidase

    PubMed Central

    De la Mora, Eugenio; Lovett, Janet E.; Blanford, Christopher F.; Garman, Elspeth F.; Valderrama, Brenda; Rudino-Pinera, Enrique

    2012-01-01

    X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O2. In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UV–Vis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-­ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O2 reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account. PMID:22525754

  6. Sinogram smoothing techniques for myocardial blood flow estimation from dose-reduced dynamic computed tomography

    PubMed Central

    Modgil, Dimple; Alessio, Adam M.; Bindschadler, Michael D.; La Rivière, Patrick J.

    2014-01-01

    Abstract. Dynamic contrast-enhanced computed tomography (CT) could provide an accurate and widely available technique for myocardial blood flow (MBF) estimation to aid in the diagnosis and treatment of coronary artery disease. However, one of its primary limitations is the radiation dose imparted to the patient. We are exploring techniques to reduce the patient dose by either reducing the tube current or by reducing the number of temporal frames in the dynamic CT sequence. Both of these dose reduction techniques result in noisy data. In order to extract the MBF information from the noisy acquisitions, we have explored several data-domain smoothing techniques. In this work, we investigate two specific smoothing techniques: the sinogram restoration technique in both the spatial and temporal domains and the use of the Karhunen–Loeve (KL) transform to provide temporal smoothing in the sinogram domain. The KL transform smoothing technique has been previously applied to dynamic image sequences in positron emission tomography. We apply a quantitative two-compartment blood flow model to estimate MBF from the time-attenuation curves and determine which smoothing method provides the most accurate MBF estimates in a series of simulations of different dose levels, dynamic contrast-enhanced cardiac CT acquisitions. As measured by root mean square percentage error (% RMSE) in MBF estimates, sinogram smoothing generally provides the best MBF estimates except for the cases of the lowest simulated dose levels (tube current=25  mAs, 2 or 3 s temporal spacing), where the KL transform method provides the best MBF estimates. The KL transform technique provides improved MBF estimates compared to conventional processing only at very low doses (<7  mSv). Results suggest that the proposed smoothing techniques could provide high fidelity MBF information and allow for substantial radiation dose savings. PMID:25642441

  7. Adaptive sampling of CT data for myocardial blood flow estimation from dose-reduced dynamic CT

    NASA Astrophysics Data System (ADS)

    Modgil, Dimple; Bindschadler, Michael D.; Alessio, Adam M.; La Rivière, Patrick J.

    2015-03-01

    Quantification of myocardial blood flow (MBF) can aid in the diagnosis and treatment of coronary artery disease (CAD). However, there are no widely accepted clinical methods for estimating MBF. Dynamic CT holds the promise of providing a quick and easy method to measure MBF quantitatively, however the need for repeated scans has raised concerns about the potential for high radiation dose. In our previous work, we explored techniques to reduce the patient dose by either uniformly reducing the tube current or by uniformly reducing the number of temporal frames in the dynamic CT sequence. These dose reduction techniques result in very noisy data, which can give rise to large errors in MBF estimation. In this work, we seek to investigate whether nonuniformly varying the tube current or sampling intervals can yield more accurate MBF estimates. Specifically, we try to minimize the dose and obtain the most accurate MBF estimate through addressing the following questions: when in the time attenuation curve (TAC) should the CT data be collected and at what tube current(s). We hypothesize that increasing the sampling rate and/or tube current during the time frames when the myocardial CT number is most sensitive to the flow rate, while reducing them elsewhere, can achieve better estimation accuracy for the same dose. We perform simulations of contrast agent kinetics and CT acquisitions to evaluate the relative MBF estimation performance of several clinically viable adaptive acquisition methods. We found that adaptive temporal and tube current sequences can be performed that impart an effective dose of about 5 mSv and allow for reductions in MBF estimation RMSE on the order of 11% compared to uniform acquisition sequences with comparable or higher radiation doses.

  8. Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

    SciTech Connect

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel; Fisher, Ryan; Tien, Chris; Simon, Steven L.; Bouville, Andre; Bolch, Wesley E.

    2011-03-15

    Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different

  9. Absorbed dose distribution for X-ray beams and beams of electrons from the Therac 10 Neptune linear accelerator.

    PubMed

    Tronc, D; Gayet, P

    1980-02-01

    After a brief presentation of the Therac 10 Neptune linear accelerator a complete set of dose distribution numerical values is given. These values define the depths on the axis as a function of the depth dose and define the penumbra (as characterized by the positions of the isodose curve intersections with parallel planes to the phantom surface) for beams of X-rays and for beams of electrons. Measurements of residual X-rays are given for a 10 MeV beam of electrons.

  10. In vivo dosimetry for estimation of effective doses in multislice CT coronary angiography

    SciTech Connect

    De Denaro, M.; Bregant, P.; Severgnini, M.; De Guarrini, F.

    2007-10-15

    In vivo dosimetry represents a technique that has been widely employed to evaluate the dose to the patient mainly in radiotherapy. Considering the increment in dose to the population due to new high-dose multislice CT examinations, such as coronary angiography, it is becoming important to more accurately know the dose to the patient. The desire to know patient dose extends even to radiological examinations. Thermoluminescent dosimeters are considered the gold standard for in vivo dosimetry, but their use is time consuming. A rapid, less labor-intensive method has been developed to perform in vivo dosimetry using radiochromic film positioned next to the patient's skin. Multislice CT scanners allow the estimation of the effective dose to the patient from the dose length product (DLP) parameter, the value of which is displayed on the acquisition console, simply multiplying the DLP by published conversion factors. The method represents only an approximation based on standard size circular phantoms and neglects the actual size of the patient. More accurate evaluations can be carried out using software-based Monte Carlo simulations. However, these methods do not consider possible dose reduction techniques, such as automatic tube-current modulation. For 22 patients effective doses measured by in vivo dosimetry and calculated by software were compared. The technique of using in vivo dosimetry measured with radiochromic film appears a promising procedure for improving the assessment of the effective dose to the patient.

  11. [Estimation of the committed effective dose of radioactive cesium and potassium by the market basket method].

    PubMed

    Tsutsumi, Tomoaki; Nabeshi, Hiromi; Ikarashi, Atsuko; Hachisuka, Akiko; Matsuda, Rieko

    2013-01-01

    The Tokyo Electric Power Company's Fukushima Daiichi nuclear power plant disaster after the Great East Japan Earthquake has caused radioactive contamination in food. Using the market basket method, total diet samples in Tokyo, Miyagi prefecture and Fukushima prefecture were analyzed for cesium-134 and -137 (radioactive cesium) and naturally occurring potassium-40 (radioactive potassium) in order to estimate the committed effective doses of these radioactive materials from food. Doses were calculated on the assumption that "not detected" corresponded to zero or to half the limit of detection (values in brackets). The estimated doses of radioactive cesium in Tokyo, Miyagi and Fukushima were 0.0021 (0.0024), 0.017 (0.018) and 0.019 (0.019) mSv/year, respectively. Although the doses in Miyagi and Fukushima were more than 8 times the dose in Tokyo, they were significantly lower than the maximum permissible dose (1 mSv/year) determined by the Ministry of Health, Labour and Welfare, Japan. The estimated doses of naturally occurring radioactive potassium in these areas were in the range of 0.17-0.20 (0.18-0.20) mSv/year, and there were no significant differences between the areas.

  12. Dose estimation based on a behavior survey of residents around the JCO facility.

    PubMed

    Fujimoto, K; Yonehara, H; Yamaguchi, Y; Endo, A

    2001-09-01

    The NIRS staff interviewed the residents in the evacuated zone around the JCO facility in Tokai-mura on 19 and 20 November, 1999, to obtain the following parameters every 30 minutes starting from 10:35 A.M. on 30 September to 6:15 A.M. on 1 October: the distance from the precipitation tank, the type of the house, positions in the house, wall materials and their thickness in order to estimate individual doses due to the accident. The ambient dose equivalents were obtained based on monitoring data during the accident. In addition, computer calculations were conducted to evaluate the conversion factor from ambient dose equivalent to effective dose equivalent as well as the shielding effect of the house or factory to estimate the effective dose equivalent to the residents. The estimated individual doses based on the behavior survey were in the range from zero to 21 mSv. The individual doses were reported to the residents during the second visit to each house and factory at the end of January, 2000.

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

    SciTech Connect

    Humphreys, S.L.; Miller, L.A.; Monroe, D.K.; Heames, T.J.

    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 the 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.

  14. Estimation of organ and effective dose due to Compton backscatter security scans

    SciTech Connect

    Hoppe, Michael E.; Schmidt, Taly Gilat

    2012-06-15

    Purpose: To estimate organ and effective radiation doses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set. Methods: Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was modeled based on specifications available in the literature. The simulations modeled a 50 kVp spectrum with 1.0 mm-aluminum-equivalent filtration and a previously measured exposure of approximately 4.6 {mu}R at 30 cm from the source. Photons and secondary interactions were tracked from the source until they reached zero kinetic energy or exited from the simulation's boundaries. The energy deposited in the phantoms' respective organs was tallied and used to calculate total organ dose and total effective dose for frontal, rear, and full scans with subjects located 30 and 75 cm from the source. Results: For a full screen, all phantoms' total effective doses were below the established 0.25 {mu}Sv standard, with an estimated maximum total effective dose of 0.07 {mu}Sv for full screen of a male child. The estimated maximum organ dose due to a full screen was 1.03 {mu}Gy, deposited in the adipose tissue of the male child phantom when located 30 cm from the source. All organ dose estimates had a coefficient of variation of less than 3% for a frontal scan and less than 11% for a rear scan. Conclusions: Backscatter security scanners deposit dose in organs beyond the skin. The effective dose is below recommended standards set by the Health Physics Society (HPS) and the American National Standards Institute (ANSI) assuming the system provides a maximum exposure of approximately 4.6 {mu}R at 30 cm.

  15. Variability in dose estimates associated with the food-chain transport and ingestion of selected radionuclides

    SciTech Connect

    Hoffman, F.O.; Gardner, R.H.; Eckerman, K.F.

    1982-06-01

    Dose predictions for the ingestion of /sup 90/Sr and /sup 137/Cs, using aquatic and terrestrial food chain transport models similar to those in the Nuclear Regulatory Commission's Regulatory Guide 1.109, are evaluated through estimating the variability of model parameters and determining the effect of this variability on model output. The variability in the predicted dose equivalent is determined using analytical and numerical procedures. In addition, a detailed discussion is included on /sup 90/Sr dosimetry. The overall estimates of uncertainty are most relevant to conditions where site-specific data is unavailable and when model structure and parameter estimates are unbiased. Based on the comparisons performed in this report, it is concluded that the use of the generic default parameters in Regulatory Guide 1.109 will usually produce conservative dose estimates that exceed the 90th percentile of the predicted distribution of dose equivalents. An exception is the meat pathway for /sup 137/Cs, in which use of generic default values results in a dose estimate at the 24th percentile. Among the terrestrial pathways of exposure, the non-leafy vegetable pathway is the most important for /sup 90/Sr. For /sup 90/Sr, the parameters for soil retention, soil-to-plant transfer, and internal dosimetry contribute most significantly to the variability in the predicted dose for the combined exposure to all terrestrial pathways. For /sup 137/Cs, the meat transfer coefficient the mass interception factor for pasture forage, and the ingestion dose factor are the most important parameters. The freshwater finfish bioaccumulation factor is the most important parameter for the dose prediction of /sup 90/Sr and /sup 137/Cs transported over the water-fish-man pathway.

  16. Comprehensive assessment of radiation dose estimates for the CORE320 study.

    PubMed

    Rybicki, Frank J; Mather, Richard T; Kumamaru, Kanako K; Brinker, Jeffrey; Chen, Marcus Y; Cox, Christopher; Matheson, Matthew B; Dewey, Marc; DiCarli, Marcelo F; Miller, Julie M; Geleijns, Jacob; George, Richard T; Paul, Narinder; Texter, John; Vavere, Andrea; Yaw, Tan Swee; Lima, Joao A C; Clouse, Melvin E

    2015-01-01

    OBJECTIVE. The purpose of this study was to comprehensively study estimated radiation doses for subjects included in the main analysis of the Combined Non-invasive Coronary Angiography and Myocardial Perfusion Imaging Using 320 Detector Computed Tomography (CORE320) study ( ClinicalTrials.gov identifier NCT00934037), a clinical trial comparing combined CT angiography (CTA) and perfusion CT with the reference standard catheter angiography plus myocardial perfusion SPECT. SUBJECTS AND METHODS. Prospectively acquired data on 381 CORE320 subjects were analyzed in four groups of testing related to radiation exposure. Radiation dose estimates were compared between modalities for combined CTA and perfusion CT with respect to covariates known to influence radiation exposure and for the main clinical outcomes defined by the trial. The final analysis assessed variations in radiation dose with respect to several factors inherent to the trial. RESULTS. The mean radiation dose estimate for the combined CTA and perfusion CT protocol (8.63 mSv) was significantly (p < 0.0001 for both) less than the average dose delivered from SPECT (10.48 mSv) and the average dose from diagnostic catheter angiography (11.63 mSv). There was no significant difference in estimated CTA-perfusion CT radiation dose for subjects who had false-positive or false-negative results in the CORE320 main analyses in a comparison with subjects for whom the CTA-perfusion CT findings were in accordance with the reference standard SPECT plus catheter angiographic findings. CONCLUSION. Radiation dose estimates from CORE320 support clinical implementation of a combined CT protocol for assessing coronary anatomy and myocardial perfusion.

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

    NASA Astrophysics Data System (ADS)

    Tian, Xiaoyu; Segars, W. P.; Dixon, R. L.; Samei, Ehsan

    2015-03-01

    Among the various metrics that quantify radiation dose in computed tomography (CT), organ dose is one of the most representative quantities reflecting patient-specific radiation burden.1 Accurate estimation of organ dose requires one to effectively model the patient anatomy and the irradiation field. As illustrated in previous studies, the patient anatomy factor can be modeled using a library of computational phantoms with representative body habitus.2 However, the modeling of irradiation field can be practically challenging, especially for CT exams performed with tube current modulation. The central challenge is to effectively quantify the scatter irradiation field created by the dynamic change of tube current. In this study, we present a convolution-based technique to effectively quantify the primary and scatter irradiation field for TCM examinations. The organ dose for a given clinical patient can then be rapidly determined using the convolution-based method, a patient-matching technique, and a library of computational phantoms. 58 adult patients were included in this study (age range: 18-70 y.o., weight range: 60-180 kg). One computational phantom was created based on the clinical images of each patient. Each patient was optimally matched against one of the remaining 57 computational phantoms using a leave-one-out strategy. For each computational phantom, the organ dose coefficients (CTDIvol-normalized organ dose) under fixed tube current were simulated using a validated Monte Carlo simulation program. Such organ dose coefficients were multiplied by a scaling factor, (CTDIvol )organ, convolution that quantifies the regional irradiation field. The convolution-based organ dose was compared with the organ dose simulated from Monte Carlo program with TCM profiles explicitly modeled on the original phantom created based on patient images. The estimation error was within 10% across all organs and modulation profiles for abdominopelvic examination. This strategy

  18. 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

  19. Development of a kinetic model and calculation of radiation dose estimates for sodium iodide-{sup 131}I in athyroid individuals

    SciTech Connect

    Rodriguez, M.

    1997-07-01

    The treatment for some thyroid carcinomas involves surgically removing the thyroid gland and administering the radiopharmaceutical Sodium iodide-{sup 131}I (NaI). A diagnostic dose of NaI is given to the patient to determine if remnant tissue from the gland remains or larger doses are administered in order to treat the malignant tissue. Past research regarding NaI uptake and retention in euthyroid individuals (normal functioning thyroid) reveal that radioiodine concentrates mainly in the thyroid tissue and the remaining material is excreted from the body. The majority of radioiodine in athyroid (without thyroid) individuals is also eliminated from the body; however, there has been recent evidence of a long-term retention phase for individuals with no radioiodine concentrating tissue. The general purpose of this study was to develop a kinetic model and estimate the absorbed dose to athyroid individuals regarding the distribution and retention of NaI.

  20. Estimation of the effects of normal tissue sparing using equivalent uniform dose-based optimization

    PubMed Central

    Senthilkumar, K.; Maria Das, K. J.; Balasubramanian, K.; Deka, A. C.; Patil, B. R.

    2016-01-01

    In this study, we intend to estimate the effects of normal tissue sparing between intensity modulated radiotherapy (IMRT) treatment plans generated with and without a dose volume (DV)-based physical cost function using equivalent uniform dose (EUD). Twenty prostate cancer patients were retrospectively selected for this study. For each patient, two IMRT plans were generated (i) EUD-based optimization with a DV-based physical cost function to control inhomogeneity (EUDWith DV) and (ii) EUD-based optimization without a DV-based physical cost function to allow inhomogeneity (EUDWithout DV). The generated plans were prescribed a dose of 72 Gy in 36 fractions to planning target volume (PTV). Mean dose, D30%, and D5% were evaluated for all organ at risk (OAR). Normal tissue complication probability was also calculated for all OARs using BioSuite software. The average volume of PTV for all patients was 103.02 ± 27 cm3. The PTV mean dose for EUDWith DV plans was 73.67 ± 1.7 Gy, whereas for EUDWithout DV plans was 80.42 ± 2.7 Gy. It was found that PTV volume receiving dose more than 115% of prescription dose was negligible in EUDWith DV plans, whereas it was 28% in EUDWithout DV plans. In almost all dosimetric parameters evaluated, dose to OARs in EUDWith DV plans was higher than in EUDWithout DV plans. Allowing inhomogeneous dose (EUDWithout DV) inside the target would achieve better normal tissue sparing compared to homogenous dose distribution (EUDWith DV). Hence, this inhomogeneous dose could be intentionally dumped on the high-risk volume to achieve high local control. Therefore, it was concluded that EUD optimized plans offer added advantage of less OAR dose as well as selectively boosting dose to gross tumor volume. PMID:27217624

  1. Calculation of absorbed dose around a facility for disposing of low activity natural radioactive waste (C3-dump).

    PubMed

    Jansen, J T M; Zoetelief, J

    2005-01-01

    A C3-dump is a facility for disposing of low activity natural radioactive waste containing the uranium series 238U, the thorium series 232Th and 40K. Only the external radiation owing to gamma rays, X-rays and annihilation photons is considered in this study. For two situations--the semi-infinite slab and the tourist geometry--the conversion coefficients from specific activity to air kerma rate at 1 m above the relevant level are calculated. In the first situation the waste material is in contact with the air but in the tourist geometry it is covered with a 1.35 m thick layer. For the calculations, the Monte Carlo radiation transport code MCNP is used. The yield and photon energy for each radionuclide are according to the database of Oak Ridge National Laboratory. For the tourist situation, the depth-dose distribution through the covering layer is calculated and extrapolated to determine the exit dose.

  2. Experimental assessment of absorbed dose to mineralized bone tissue from internal emitters: An electron paramagnetic resonance study

    SciTech Connect

    Desrosiers, M.F.

    1994-12-31

    EPR resonances attributable to radiation-induced centers in hydroxyapatite were not detectable in bone samples supplied by the USTUR. These centers are the basis for imaging and dose assessment. Presumable, the short range of the alpha particles emitted precluded the formation of appreciable amounts of hydroxyapatite centers. However, one bone sample did offer a suggestion of hydroxyapatite centers and newly-developed methods to extract this information will be pursued.

  3. PHITS simulations of the Protective curtain experiment onboard the Service module of ISS: Comparison with absorbed doses measured with TLDs

    NASA Astrophysics Data System (ADS)

    Ploc, Ondřej; Sihver, Lembit; Kartashov, Dmitry; Shurshakov, Vyacheslav; Tolochek, Raisa

    2013-12-01

    "Protective curtain" was the physical experiment onboard the International Space Station (ISS) aimed on radiation measurement of the dose - reducing effect of the additional shielding made of hygienic water-soaked wipes and towels placed on the wall in the crew cabin of the Service module Zvezda. The measurements were performed with 12 detector packages composed of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs) placed at the Protective curtain, so that they created pairs of shielded and unshielded detectors.

  4. Gold nanoparticle-aided brachytherapy with vascular dose painting: Estimation of dose enhancement to the tumor endothelial cell nucleus

    SciTech Connect

    Ngwa, Wilfred; Makrigiorgos, G. Mike; Berbeco, Ross I.

    2012-01-15

    Purpose: Theoretical microdosimetry at the subcellular level is employed in this study to estimate the dose enhancement to tumor endothelial cell nuclei, caused by radiation-induced photo/Auger electrons originating from gold nanoparticles (AuNPs) targeting the tumor endothelium, during brachytherapy. Methods: A tumor vascular endothelial cell (EC) is modeled as a slab of 2 {mu}m (thickness) x 10 {mu}m (length) x 10 {mu}m (width). The EC contains a nucleus of 5 {mu}m diameter and thickness of 0.5-1 {mu}m, corresponding to nucleus size 5%-10% of cellular volume, respectively. Analytic calculations based on the electron energy loss formula of Cole were carried out to estimate the dose enhancement to the nucleus caused by photo/Auger electrons from AuNPs attached to the exterior surface of the EC. The nucleus dose enhancement factor (nDEF), representing the ratio of the dose to the nucleus with and without the presence of gold nanoparticles was calculated for different AuNP local concentrations. The investigated concentration range considers the potential for significantly higher local concentration near the EC due to preferential accumulation of AuNP in the tumor vasculature. Four brachytherapy sources: I-125, Pd-103, Yb-169, and 50 kVp x-rays were investigated. Results: For nucleus size of 10% of the cellular volume and AuNP concentrations ranging from 7 to 140 mg/g, brachytherapy sources Pd-103, I-125, 50 kVp, and Yb-169 yielded nDEF values of 5.6-73, 4.8-58.3, 4.7-56.6, and 3.2-25.8, respectively. Meanwhile, for nucleus size 5% of the cellular volume in the same concentration range, Pd-103, I-125, 50 kVp, and Yb-169 yielded nDEF values of 6.9-79.2, 5.1-63.2, 5.0-61.5, and 3.3-28.3, respectively. Conclusions: The results predict that a substantial dose boost to the nucleus of endothelial cells can be achieved by applying tumor vasculature-targeted AuNPs in combination with brachytherapy. Such vascular dose boosts could induce tumor vascular shutdown, prompting

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

    SciTech Connect

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

    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, 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 (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

  6. MAXINE: An improved methodology for estimating maximum individual dose from chronic atmospheric radioactive releases

    SciTech Connect

    Hamby, D.M.

    1994-02-01

    An EXCEL{reg_sign} spreadsheet has been developed that, when combined with the PC version of XOQDOQ, will generate estimates of maximum individual dose from routine atmospheric releases of radionuclides. The spreadsheet, MAXINE, utilizes a variety of atmospheric dispersion factors to calculate radiation dose as recommended by the US Nuclear Regulatory Commission in Regulatory Guide 1.109 [USNRC 1977a]. The methodology suggested herein includes use of both the MAXINE spreadsheet and the PC version of XOQDOQ.

  7. Programmable flow system for automation of oxygen radical absorbance capacity assay using pyrogallol red for estimation of antioxidant reactivity.

    PubMed

    Ramos, Inês I; Gregório, Bruno J R; Barreiros, Luísa; Magalhães, Luís M; Tóth, Ildikó V; Reis, Salette; Lima, José L F C; Segundo, Marcela A

    2016-04-01

    An automated oxygen radical absorbance capacity (ORAC) method based on programmable flow injection analysis was developed for the assessment of antioxidant reactivity. The method relies on real time spectrophotometric monitoring (540 nm) of pyrogallol red (PGR) bleaching mediated by peroxyl radicals in the presence of antioxidant compounds within the first minute of reaction, providing information about their initial reactivity against this type of radicals. The ORAC-PGR assay under programmable flow format affords a strict control of reaction conditions namely reagent mixing, temperature and reaction timing, which are critical parameters for in situ generation of peroxyl radical from 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH). The influence of reagent concentrations and programmable flow conditions on reaction development was studied, with application of 37.5 µM of PGR and 125 mM of AAPH in the flow cell, guaranteeing first order kinetics towards peroxyl radicals and pseudo-zero order towards PGR. Peroxyl-scavenging reactivity of antioxidants, bioactive compounds and phenolic-rich beverages was estimated employing the proposed methodology. Recovery assays using synthetic saliva provided values of 90 ± 5% for reduced glutathione. Detection limit calculated using the standard antioxidant compound Trolox was 8 μM. RSD values were <3.4 and <4.9%, for intra and inter-assay precision, respectively. Compared to previous batch automated ORAC assays, the developed system also accounted for high sampling frequency (29 h(-1)), low operating costs and low generation of waste.

  8. Estimation of Radiobiologic Parameters and Equivalent Radiation Dose of Cytotoxic Chemotherapy in Malignant Glioma

    SciTech Connect

    Jones, Bleddyn . E-mail: b.jones.1@bham.ac.uk; Sanghera, Paul

    2007-06-01

    Purpose: To determine the radiobiologic parameters for high-grade gliomas. Methods and Materials: The biologic effective dose concept is used to estimate the {alpha}/{beta} ratio and K (dose equivalent for tumor repopulation/d) for high-grade glioma patients treated in a randomized fractionation trial. The equivalent radiation dose of temozolomide (Temodar) chemotherapy was estimated from another randomized study. The method assumes that the radiotherapy biologic effective dose is proportional to the adjusted radiotherapy survival duration of high-grade glioma patients. Results: The median tumor {alpha}/{beta} and K estimate is 9.32 Gy and 0.23 Gy/d, respectively. Using the published surviving fraction after 2-Gy exposure (SF{sub 2}) data, and the above {alpha}/{beta} ratio, the estimated median {alpha} value was 0.077 Gy{sup -1}, {beta} was 0.009 Gy{sup -2}, and the cellular doubling time was 39.5 days. The median equivalent biologic effective dose of temozolomide was 11.03 Gy{sub 9.3} (equivalent to a radiation dose of 9.1 Gy given in 2-Gy fractions). Random sampling trial simulations based on a cure threshold of 70 Gy in high-grade gliomas have shown the potential increase in tumor cure with dose escalation. Partial elimination of hypoxic cells (by chemical hypoxic cell sensitizers or carbon ion therapy) has suggested that considerable gains in tumor control, which are further supplemented by temozolomide, are achievable. Conclusion: The radiobiologic parameters for human high-grade gliomas can be estimated from clinical trials and could be used to inform future clinical trials, particularly combined modality treatments with newer forms of radiotherapy. Other incurable cancers should be studied using similar radiobiologic analysis.

  9. Childhood leukaemia incidence around French nuclear installations using geographic zoning based on gaseous discharge dose estimates

    PubMed Central

    Evrard, A-S; Hémon, D; Morin, A; Laurier, D; Tirmarche, M; Backe, J-C; Chartier, M; Clavel, J

    2006-01-01

    The present study investigated for the first time the incidence of childhood leukaemia (1990–2001) around French nuclear installations using a geographic zoning based on estimated doses to the red bone marrow due to gaseous radioactive discharges. The observed number of cases of acute leukaemia (O=750) in 40 km2 centred on 23 French nuclear installations between 1990 and 2001 was lower than expected (E=795.01), although not significantly so (standardised incidence ratio SIR=0.94, 95% confidence interval=(0.88–1.01)). In none of the five zones defined on the basis of the estimated doses was the SIR significantly >1. There was no evidence of a trend in SIR with the estimated doses for all the children or for any of the three age groups studied. This study confirmed that there was no evidence of an increased incidence of childhood leukaemia around the 23 French nuclear sites. PMID:16622448

  10. Fetal radiation dose estimates for I-131 sodium iodide in cases where conception occurs after administration

    SciTech Connect

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

    1999-01-01

    After administration of I-131 to the female patient, the possibility of radiation exposure of the embryo/fetus exists if the patient becomes pregnant while radioiodine remains in the body. Fetal radiation dose estimates for such cases were calculated. Doses were calculated for various maternal thyroid uptakes and time intervals between administration and conception, including euthyroid and hyperthyroid cases. The maximum fetal dose calculating was about 9.8E-03 mGy/MBq, which occurred with 100% maternal thyroid uptake and a 1 week interval between administration and conception. Placental crossover of the small amount of radioiodine remaining 90 days after conception was also considered. Such crossover could result in an additional fetal dose of 9.8E-05 mGy/MBq and a maximum fetal thyroid self dose of 3.5E-04 mGy/MBq.

  11. Parameterizing dose-response models to estimate relative potency functions directly.

    PubMed

    Dinse, Gregg E; Umbach, David M

    2012-10-01

    Many comparative analyses of toxicity assume that the potency of a test chemical relative to a reference chemical is constant, but employing such a restrictive assumption uncritically may generate misleading conclusions. Recent efforts to characterize non-constant relative potency rely on relative potency functions and estimate them secondarily after fitting dose-response models for the test and reference chemicals. We study an alternative approach of specifying a relative potency model a priori and estimating it directly using the dose-response data from both chemicals. We consider a power function in dose as a relative potency model and find that it keeps the two chemicals' dose-response functions within the same family of models for families typically used in toxicology. When differences in the response limits for the test and reference chemicals are attributable to the chemicals themselves, the older two-stage approach is the more convenient. When differences in response limits are attributable to other features of the experimental protocol or when response limits do not differ, the direct approach is straightforward to apply with nonlinear regression methods and simplifies calculation of simultaneous confidence bands. We illustrate the proposed approach using Hill models with dose-response data from U.S. National Toxicology Program bioassays. Though not universally applicable, this method of estimating relative potency functions directly can be profitably applied to a broad family of dose-response models commonly used in toxicology.

  12. 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

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

    PubMed

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

    2015-01-01

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

  14. Patient-specific dose estimation for pediatric abdomen-pelvis CT

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  15. Radiation dose estimates for typical piloted NTR lunar and Mars mission engine operations

    SciTech Connect

    Schnitzler, B.G. ); Borowski, S.K. . Lewis Research Center)

    1991-01-01

    The natural and manmade radiation environments to be encountered during lunar and Mars missions are qualitatively summarized. The computational methods available to characterize the radiation environment produced by an operating nuclear propulsion system are discussed. Mission profiles and vehicle configurations are presented for a typical all-propulsive, fully reusable lunar mission and for a typical all-propulsive Mars mission. Estimates of crew location biological doses are developed for all propulsive maneuvers. Post-shutdown dose rates near the nuclear engine are estimated at selected mission times. 15 refs., 4 figs.

  16. Calibration of GafChromic EBT3 for absorbed dose measurements in 5 MeV proton beam and {sup 60}Co γ-rays

    SciTech Connect

    Vadrucci, M. Ronsivalle, C.; Marracino, F.; Montereali, R. M.; Picardi, L.; Piccinini, M.; Vincenti, M. A.; Esposito, G.; De Angelis, C.; Cherubini, R.; Pimpinella, M.

    2015-08-15

    Purpose: To study EBT3 GafChromic film in low-energy protons, and for comparison purposes, in a reference {sup 60}Co beam in order to use it as a calibrated dosimetry system in the proton irradiation facility under construction within the framework of the Oncological Therapy with Protons (TOP)-Intensity Modulated Proton Linear Accelerator for RadioTherapy (IMPLART) Project at ENEA-Frascati, Italy. Methods: EBT3 film samples were irradiated at the Istituto Nazionale di Fisica Nucleare—Laboratori Nazionali di Legnaro, Italy, with a 5 MeV proton beam generated by a 7 MV Van de Graaff CN accelerator. The nominal dose rates used were 2.1 Gy/min and 40 Gy/min. The delivered dose was determined by measuring the particle fluence and the energy spectrum in air with silicon surface barrier detector monitors. A preliminary study of the EBT3 film beam quality dependence in low-energy protons was conducted by passively degrading the beam energy. EBT3 films were also irradiated at ENEA-National Institute of Ionizing Radiation Metrology with gamma radiation produced by a {sup 60}Co source characterized by an absorbed dose to water rate of 0.26 Gy/min as measured by a calibrated Farmer type ionization chamber. EBT3 film calibration curves were determined by means of a set of 40 film pieces irradiated to various doses ranging from 0.5 Gy to 30 Gy absorbed dose to water. An EPSON Expression 11000XL color scanner in transmission mode was used for film analysis. Scanner response stability, intrafilm uniformity, and interfilm reproducibility were verified. Optical absorption spectra measurements were performed on unirradiated and irradiated EBT3 films to choose the most sensitive color channel to the dose range used. Results: EBT3 GafChromic films show an under response up to about 33% for low-energy protons with respect to {sup 60}Co gamma radiation, which is consistent with the linear energy transfer dependence already observed with higher energy protons, and a negligible dose

  17. Combined methodology for estimating dose rates and health effects from exposure to radioactive pollutants

    SciTech Connect

    Dunning, D.E. Jr.; Leggett, R.W.; Yalcintas, M.G.

    1980-12-01

    The work described in the report is basically a synthesis of two previously existing computer codes: INREM II, developed at the Oak Ridge National Laboratory (ORNL); and CAIRD, developed by the Environmental Protection Agency (EPA). The INREM II code uses contemporary dosimetric methods to estimate doses to specified reference organs due to inhalation or ingestion of a radionuclide. The CAIRD code employs actuarial life tables to account for competing risks in estimating numbers of health effects resulting from exposure of a cohort to some incremental risk. The combined computer code, referred to as RADRISK, estimates numbers of health effects in a hypothetical cohort of 100,000 persons due to continuous lifetime inhalation or ingestion of a radionuclide. Also briefly discussed in this report is a method of estimating numbers of health effects in a hypothetical cohort due to continuous lifetime exposure to external radiation. This method employs the CAIRD methodology together with dose conversion factors generated by the computer code DOSFACTER, developed at ORNL; these dose conversion factors are used to estimate dose rates to persons due to radionuclides in the air or on the ground surface. The combination of the life table and dosimetric guidelines for the release of radioactive pollutants to the atmosphere, as required by the Clean Air Act Amendments of 1977.

  18. A novel method of estimating effective dose from the point dose method: a case study—parathyroid CT scans

    NASA Astrophysics Data System (ADS)

    Januzis, Natalie; Nguyen, Giao; Hoang, Jenny K.; Lowry, Carolyn; Yoshizumi, Terry T.

    2015-02-01

    The purpose of this study was to validate a novel approach of applying a partial volume correction factor (PVCF) using a limited number of MOSFET detectors in the effective dose (E) calculation. The results of the proposed PVCF method were compared to the results from both the point dose (PD) method and a commercial CT dose estimation software (CT-Expo). To measure organ doses, an adult female anthropomorphic phantom was loaded with 20 MOSFET detectors and was scanned using the non-contrast and 2 phase contrast-enhanced parathyroid imaging protocols on a 64-slice multi-detector computed tomography scanner. E was computed by three methods: the PD method, the PVCF method, and the CT-Expo method. The E (in mSv) for the PD method, the PVCF method, and CT-Expo method was 2.6  ±  0.2, 1.3  ±  0.1, and 1.1 for the non-contrast scan, 21.9  ±  0.4, 13.9  ±  0.2, and 14.6 for the 1st phase of the contrast-enhanced scan, and 15.5  ±  0.3, 9.8  ±  0.1, and 10.4 for the 2nd phase of the contrast-enhanced scan, respectively. The E with the PD method differed from the PVCF method by 66.7% for the non-contrast scan, by 44.9% and by 45.5% respectively for the 1st and 2nd phases of the contrast-enhanced scan. The E with PVCF was comparable to the results from the CT-Expo method with percent differences of 15.8%, 5.0%, and 6.3% for the non-contrast scan and the 1st and 2nd phases of the contrast-enhanced scan, respectively. To conclude, the PVCF method estimated E within 16% difference as compared to 50-70% in the PD method. In addition, the results demonstrate that E can be estimated accurately from a limited number of detectors.

  19. Estimation of doses to personnel and patients during endovascular brachytherapy applications.

    PubMed

    Kirisits, Christian; Hefner, Alfred; Wexberg, Paul; Pokrajac, Boris; Glogar, Dietmar; Pötter, Richard; Georg, Dietmar

    2004-01-01

    In the last few years coronary endovascular brachytherapy using gamma- and beta-emitting radionuclides has been established as a standard treatment procedure to prevent restenosis after percutaneous coronary interventions. Direct measurements and calculations were made to determine personnel doses and organ doses of patients due to gamma rays of 192Ir and beta rays of 90Sr/90Y and 32P sources. In general, our results show that the dose levels are low compared with the X-ray exposure from angiography. The dose rate from bremsstrahlung at 1 m distance from a device containing a 90Sr/90Y source of 2.3 GBq is 4 micro Sv h(-1). The skin dose from beta rays during source transfer into and from the patient was estimated with the directional dose equivalent H'(0.07) of 10 micro Sv at 1 m distance from the catheter. By maintaining safe distances, the dose levels can be kept well within annual dose limits.

  20. Estimated Fluoride Doses from Toothpastes Should be Based on Total Soluble Fluoride

    PubMed Central

    Oliveira, Maria José L.; Martins, Carolina C.; Paiva, Saul M.; Tenuta, Livia M. A.; Cury, Jaime A.

    2013-01-01

    The fluoride dose ingested by young children may be overestimated if based on levels of total fluoride (TF) rather than levels of bioavailable fluoride (total soluble fluoride—TSF) in toothpaste. The aim of the present study was to compare doses of fluoride intake based on TF and TSF. Fluoride intake in 158 Brazilian children aged three and four years was determined after tooth brushing with their usual toothpaste (either family toothpaste (n = 80) or children’s toothpaste (n = 78)). The estimated dose (mg F/day/Kg of body weight) of TF or TSF ingested was calculated from the chemical analysis of the toothpastes. Although the ingested