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Sample records for absorbed doses

  1. [Absorbed doses in dental radiology].

    Science.gov (United States)

    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.

  2. Absorbed dose by a CMOS in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Valero L, C. Y.; Guzman G, K. A.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L. C., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-10-15

    Absorbed dose by a complementary metal oxide semiconductor (CMOS) circuit as part of a pacemaker, has been estimated using Monte Carlo calculations. For a cancer patient who is a pacemaker carrier, scattered radiation could damage pacemaker CMOS circuits affecting patient's health. Absorbed dose in CMOS circuit due to scattered photons is too small and therefore is not the cause of failures in pacemakers, but neutron calculations shown an absorbed dose that could cause damage in CMOS due to neutron-hydrogen interactions. (Author)

  3. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: fermineutron@yahoo.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-06-15

    The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor (CMOS), has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1.522 x 10{sup -17} Gy per neutron emitted by the source. (Author)

  4. Methods of calculating radiation absorbed dose.

    Science.gov (United States)

    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.

  5. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C. Y.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-11-15

    The absorbed dose due to neutrons by a Complementary Metal Oxide Semiconductor (CMOS) has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes a patient that must be treated by radiotherapy with a linear accelerator; the pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. When the Linac is working in Bremsstrahlung mode an undesirable neutron field is produced due to photoneutron reactions; these neutrons could damage the CMOS putting the patient at risk during the radiotherapy treatment. In order to estimate the neutron dose in the CMOS a Monte Carlo calculation was carried out where a full radiotherapy vault room was modeled with a W-made spherical shell in whose center was located the source term of photoneutrons produced by a Linac head operating in Bremsstrahlung mode at 18 MV. In the calculations a phantom made of tissue equivalent was modeled while a beam of photoneutrons was applied on the phantom prostatic region using a field of 10 x 10 cm{sup 2}. During simulation neutrons were isotropically transported from the Linac head to the phantom chest, here a 1 {theta} x 1 cm{sup 2} cylinder made of polystyrene was modeled as the CMOS, where the neutron spectrum and the absorbed dose were estimated. Main damages to CMOS are by protons produced during neutron collisions protective cover made of H-rich materials, here the neutron spectrum that reach the CMOS was calculated showing a small peak around 0.1 MeV and a larger peak in the thermal region, both connected through epithermal neutrons. (Author)

  6. Measurement of absorbed dose and proposed radiation exposure level

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Takayuki; Koizumi, Masayuki; Furukawa, Tomo [Tokai Univ., Isehara, Kanagawa (Japan). Hospital

    2003-03-01

    Absorbed dose was measured in clinical X-ray examinations using thermoluminescence dosimeter (TLD). Moreover, we distributed the levels of radiation exposure into 3 classes. The presumed dose of the internal organs, e.g., uterus dose, was computed to depth doses with a surface dose. This information provides a prediction of the influence of radiation, and the examination can be performed with the informed consent of the patient. Moreover, we examined the distribution of the level of absorbed dose. We proposed two kinds of radiation exposure level, one to the fetus in a pregnant woman and a general level of radiation exposure that is not applied to pregnant women. The levels were as follows: 0.5 mGy and 100 mGy were considered the boundaries for fetal radiation exposure in a pregnant woman, and 200 mGy and 3 Gy were considered the boundaries for the general level of radiation exposure (excluding pregnant women). (author)

  7. Thyroid absorbed dose using TLDs during mammography

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez A, M.; Melendez L, M. [IPN, Centro de Investigacion y de Estudios Avanzados, Av. IPN 2508, Col. San Pedro Zacatenco, 07360 Mexico D. F. (Mexico); Davila M, P., E-mail: biomedica.sst@gmail.com [UNEME-DEDICAM de Ciudad Victoria, Circuito Medico s/n, 87087 Ciudad Victoria, Tamaulipas (Mexico)

    2015-10-15

    Full text: In this study, the mean glandular dose (MGD) and the thyroid dose (D Thy) were measured in 200 women screened with mammography in Cranio caudal (Cc) and mediolateral oblique projections. All mammograms were performed with Giotto-Ims (6000-14-M2 Model) equipment, which was verified to meet the criteria of quality of NOM-229-Ssa-2002. During audits performance and HVL, for each anode filter combinations was measured with the camera Radcal mammography equipment 10 X 6-6M (HVL = 0.26 mm Al). D Thy measurements were performed with TLD dosimeters (LiF:Mn) , that were read with the Harshaw 3500 TLD reader. The MGD, was obtained according to the UK and European protocols for mammographic dosimetry using a plane parallel chamber (Standard Imaging, Model A-600) calibrated by a radiation beam UW-23-Mo (= 0.279 mm Al HVL). A comparative statistical analysis was carried out with the measured MGD and D thy. The thyroid mean dose was 0.063 mGy and 0.078 mGy for Cc and mediolateral oblique respectively. There is a linear correlation between the MGD and the D Thy slightly influenced by the anode-filter combination. Using a 95% for the confidence interval in MGD (1.07 mGy), the 90% of measurements are in agreement with the established uncertainty limits. The D Thy are lower than the MGD. There is no risk for cancer induction in thyroid in women due to mammography screening. (Author)

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

    Science.gov (United States)

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

    2005-09-01

    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 phantoms and for a single Lucite phantom for photon energies between 60Co and 18 MV photons. For Solid Water 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.

  9. Absorbed Dose Distribution in a Pulse Radiolysis Optical Cell

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    When a liquid solution in an optical cell is irradiated by an intense pulsed electron beam, it may be important in the chemical analysis of the solution to know the distribution of energy deposited throughout the cell. For the present work, absorbed dose distributions were measured by thin...

  10. Absorbed Doses to Patients in Nuclear Medicine; Doskatalogen foer nukleaermedicin

    Energy Technology Data Exchange (ETDEWEB)

    Leide-Svegborn, Sigrid; Mattsson, Soeren; Nosslin, Bertil [Universitetssjukhuset MAS, Malmoe (Sweden). Avd. foer radiofysik; Johansson, Lennart [Norrlands Universitetssjukhus, Umeaa (Sweden). Avd. foer radiofysik

    2004-09-01

    The work with a Swedish catalogue of radiation absorbed doses to patients undergoing nuclear medicine investigations has continued. After the previous report in 1999, biokinetic data and dose estimates (mean absorbed dose to various organs and tissues and effective dose) have been produced for a number of substances: {sup 11}C- acetate, {sup 11}C- methionine, {sup 18}F-DOPA, whole antibody labelled with either {sup 99m}Tc, {sup 111}In, {sup 123}I or {sup 131}I, fragment of antibody, F(ab'){sub 2} labelled with either {sup 99m}Tc, {sup 111}In, {sup 123}I or {sup 131}I and fragment of antibody, Fab' labelled with either {sup 99m}Tc, {sup 111}In, {sup 123}I or {sup 131}I. The absorbed dose estimates for these substances have been made from published biokinetic information. For other substances of interest, e.g. {sup 14}C-urea (children age 3-6 years), {sup 14}C-glycocholic acid, {sup 14}C-xylose and {sup 14}C-triolein, sufficient literature data have not been available. Therefore, a large number of measurements on patients and volunteers have been carried out, in order to determine the biokinetics and dosimetry for these substances. Samples of breast milk from 50 mothers, who had been subject to nuclear medicine investigations, have been collected at various times after administration of the radiopharmaceutical to the mother. The activity concentration in the breast milk samples has been measured. The absorbed dose to various organs and tissues and the effective dose to the child who ingests the milk have been determined for 17 different radiopharmaceuticals. Based on these results revised recommendations for interruption of breast-feeding after nuclear medicine investigations are suggested.

  11. Space radiation absorbed dose distribution in a human phantom

    Science.gov (United States)

    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

  12. Photon spectrum and absorbed dose in brain tumor

    Energy Technology Data Exchange (ETDEWEB)

    Silva S, A. [General Electric Healthcare, Antonio Dovali Jaime 70, Torre A 3er. piso, Col. Santa Fe, 01210 Mexico D. F. (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico); Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    Using Monte Carlo methods a BOMAB phantom inside a treatment hall with a brain tumor nearby the pituitary gland was treated with photons produced by a Varian 6 MV linac. The photon spectrum and the absorbed dose were calculated in the tumor, pituitary gland and the head. The treatment beam was collimated to illuminate only the tumor volume; however photons were noticed in the gland. Photon fluence reaching the tumor is 78.1 times larger than the fluence in the pituitary gland, on the other hand the absorbed dose in the tumor is 188 times larger than the dose in the gland because photons that reach the pituitary gland are scattered, by the head and the tumor, through Compton effect. (Author)

  13. Sensors of absorbed dose of ionizing radiation based on mosfet

    Directory of Open Access Journals (Sweden)

    Perevertaylo V. L.

    2010-10-01

    Full Text Available The requirements to technology and design of p-channel and n-channel MOS transistors with a thick oxide layer designed for use in the capacity of integral dosimeters of absorbed dose of ionizing radiation are defined. The technology of radiation-sensitive MOS transistors with a thick oxide in the p-channel and n-channel version is created.

  14. Maximum embryo absorbed dose from intravenous urography: interhospital variations

    Energy Technology Data Exchange (ETDEWEB)

    Damilakis, J.; Perisinakis, K. [University of Crete (Greece). Dept. of Medical Physics; Koukourakis, M. [University of Crete (Greece). Dept. of Radiology; Gourtsoyiannis, N. [University Hospital of Iraklion, Crete (Greece). Dept. of Radiotherapy

    1997-12-01

    The purpose of this study was to determine the maximum embryo dose during intravenous urography (IVU) examinations, when inadvertent irradiation of a pregnant woman occurs, and to investigate the variation of doses received from different institutions. Doses at average embryo depth from IVU examinations have been measured in four institutions using a Rando phantom and thermoluminescent crystals. In order to estimate the maximum range of embryo doses, radiologists were asked to carry out the examinations with the same technique as in female patients with acute ureteral obstruction. The range of doses estimated at embryo depth for the institutions participating in this study was 5.77 to 35.2 mGy. The considerable interhospital variation found in dose can be explained by different equipment and techniques used. A simple method of estimating embryo dose from pelvic radiographs reported previously was found to be also applicable to IVU examinations. Absorbed dose at 6 cm, the average embryo depth, was found significantly less than 50 mGy. (Author).

  15. Radiochromic Plastic Films for Accurate Measurement of Radiation Absorbed Dose and Dose Distributions

    DEFF Research Database (Denmark)

    McLaughlin, W. L.; Miller, Arne; Fidan, S.

    1977-01-01

    of many polymeric systems in industrial radiation processing. The result is that errors due to energy dependence of response of the radiation sensor are effectively reduced, since the spectral sensitivity of the dose meter matches that of the polymer of interest, over a wide range of photon and electron...... in polymeric solutions can be cast into flexible free-standing thin films of uniform thickness and reproducible response to ultraviolet and ionizing radiation. The increase in optical density versus energy deposited by radiation is linear over a wide range of doses and is for practical purposes independent......Thin radiochromic dye films are useful for measuring large radiation absorbed doses (105–108 rads) and for high-resolution imaging of dose patterns produced by penetrating radiation beams passing through non-homogeneous media. Certain types of amino-substituted triarylmethane cyanides dissolved...

  16. Absorbed dose determination in photon fields using the tandem method

    CERN Document Server

    Marques-Pachas, J F

    1999-01-01

    The purpose of this work is to develop an alternative method to determine the absorbed dose and effective energy of photons with unknown spectral distributions. It includes a 'tandem' system that consists of two thermoluminescent dosemeters with different energetic dependence. LiF: Mg, Ti, CaF sub 2 : Dy thermoluminescent dosemeters and a Harshaw 3500 reading system are employed. Dosemeters are characterized with sup 9 sup 0 Sr- sup 9 sup 0 Y, calibrated with the energy of sup 6 sup 0 Co and irradiated with seven different qualities of x-ray beams, suggested by ANSI No. 13 and ISO 4037. The answers of each type of dosemeter are adjusted to a function that depends on the effective energy of photons. The adjustment is carried out by means of the Rosenbrock minimization algorithm. The mathematical model used for this function includes five parameters and has a gauss and a straight line. Results show that the analytical functions reproduce the experimental data of the answers, with a margin of error of less than ...

  17. Blood compounds irradiation process: assessment of absorbed dose using Fricke and Thermoluminescent dosimetric systems

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Gabriela de Amorim; Squair, Peterson Lima; Pinto, Fausto Carvalho; Belo, Luiz Claudio Meira; Grossi, Pablo Andrade [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN/MG), Belo Horizonte, MG (Brazil)], e-mail: gas@cdtn.br, e-mail: pls@cdtn.br, e-mail: fcp@cdtn.br, e-mail: lcmb@cdtn.br, e-mail: pabloag@cdtn.br

    2009-07-01

    The assessment of gamma absorbed doses in irradiation facilities allows the quality assurance and control of the irradiation process. The liability of dose measurements is assign to the metrological procedures adopted including the uncertainty evaluation. Fricke and TLD 800 dosimetric systems were used to measure absorbed dose in the blood compounds using the methodology presented in this paper. The measured absorbed doses were used for evaluating the effectiveness of the irradiation procedure and the gamma dose absorption inside the irradiation room of a gamma irradiation facility. The radiation eliminates the functional and proliferative capacities of donor T-lymphocytes, preventing Transfusion associated graft-versus-host disease (TA-GVHD), a possible complication of blood transfusions. The results show the applicability of such dosimetric systems in quality assurance programs, assessment of absorbed doses in blood compounds and dose uniformity assign to the blood compounds irradiation process by dose measurements in a range between 25 Gy and 100 Gy. (author)

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

    Science.gov (United States)

    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).

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Aydogan, B.; Miller, L.F. [Univ. of Tennessee, Knoxville, TN (United States). Nuclear Engineering Dept.; Sparks, R.B. [Oak Ridge Inst. for Science and Education, TN (United States); Stubbs, J.B. [Radiation Dosimetry Systems of Oak Ridge, Inc., Knoxville, TN (United States)

    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.

  1. Isoeffective dose: a concept for biological weighting of absorbed dose in proton and heavier-ion therapies

    CERN Document Server

    Wambersie, A; Menzel, H G; Gahbauer, R; DeLuca, P M; Hendry, J H; Jones, D T L

    2011-01-01

    When reporting radiation therapy procedures, International Commission on Radiation Units and Measurements (ICRU) recommends specifying absorbed dose at/in all clinically relevant points and/or volumes. In addition, treatment conditions should be reported as completely as possible in order to allow full understanding and interpretation of the treatment prescription. However, the clinical outcome does not only depend on absorbed dose but also on a number of other factors such as dose per fraction, overall treatment time and radiation quality radiation biology effectiveness (RBE). Therefore, weighting factors have to be applied when different types of treatments are to be compared or to be combined. This had led to the concept of `isoeffective absorbed dose', introduced by ICRU and International Atomic Energy Agency (IAEA). The isoeffective dose D(IsoE) is the dose of a treatment carried out under reference conditions producing the same clinical effects on the target volume as those of the actual treatment. It i...

  2. Absorbed doses on patients undergoing tomographic exams for pre-surgery planning of dental implants

    Energy Technology Data Exchange (ETDEWEB)

    Zenobio, M.A.F. [Centro de Desenvolvimento da Tecnologia Nuclear, Comissao Nacional de Energia Nuclear, Caixa Postal 941, CEP 30123-970 Belo Horizonte, MG (Brazil)]. E-mail: silvata@cdtn.br; da Silva, T.A. [Centro de Desenvolvimento da Tecnologia Nuclear, Comissao Nacional de Energia Nuclear, Caixa Postal 941, CEP 30123-970 Belo Horizonte, MG (Brazil)]. E-mail: madelon@cdtn.br

    2007-06-15

    The thermoluminescent (TL) dosimetry was used to measure entrance skin absorbed doses at anatomical points close to critical organs of patients undergoing tomographic techniques as part of a pre-surgery planning for dental implants. The dosimetric procedure was applied in 19 patients, and absorbed doses could be measured with a combined uncertainty down to 14%. Results showed that patient doses may be increased by a factor of 20 in the helical computed tomography compared to panoramic and spiral conventional tomographic exams.

  3. Absorbed Dose Distributions in Irradiated Plastic Tubing and Wire Insulation

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1979-01-01

    Plastic tubing and wire insulation were simulated by radiochromic dye dosimeter films having electron absorbing properties similar to the materials of interest (polyethylene and PVC). A 400-keV electron accelerator was used to irradiate from 1, 2, 3 and 4 sides simulating possible industrial...

  4. Absorbed dose evaluations in retrospective dosimetry: Methodological developments using quartz

    DEFF Research Database (Denmark)

    Bailiff, I.K.; Bøtter-Jensen, L.; Correcher, V.

    2000-01-01

    Dose evaluation procedures based on luminescence techniques were applied to 50 quartz samples extracted from bricks that had been obtained from populated or partly populated settlements in Russia and Ukraine downwind of the Chernobyl NPP. Determinations of accrued dose in the range similar to 30-...

  5. Evaluation of the absorbed dose in odontological computerized tomography; Avaliacao da dose absorvida em tomografia computadorizada odontologica

    Energy Technology Data Exchange (ETDEWEB)

    Legnani, Adriano; Schelin, Hugo R.; Rocha, Anna Silvia P.S. da, E-mail: schelin@utfpr.edu.b, E-mail: anna@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2011-10-26

    This paper evaluated the absorbed dose at the surface entry known as 'cone beam computed tomography' (CBCT) in odontological computerized tomography. Examination were simulated with CBCT for measurements of dose. A phantom were filled with water, becoming scatter object of radiation. Thermoluminescent dosemeters were positioned on points correspondent to eyes and salivary glands

  6. Plastic film materials for dosimetry of very large absorbed doses

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne; Abdel-Rahim, F.

    1985-01-01

    Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up...... to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response at such high doses are polyethylene terephthalate, high-density polyethylene, dyed polyvinylchloride...

  7. Patient absorbed radiation doses estimation related to irradiation anatomy; Estimativa de dose absorvida pelo paciente relacionada a anatomia irradiada

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Flavio Augusto Penna; Soares, Amanda Anastacio; Kahl, Gabrielly Gomes, E-mail: prof.flavio@gmail.com, E-mail: amanda-a-soares@hotmail.com, E-mail: gabriellygkahl@gmail.com [Instituto Federal de Eduacao, Ciencia e Tecnologia de Santa Catarina (IFSC), Florianopolis, SC (Brazil)

    2014-07-01

    Developed a direct equation to estimate the absorbed dose to the patient in x-ray examinations, using electric, geometric parameters and filtering combined with data from irradiated anatomy. To determine the absorbed dose for each examination, the entrance skin dose (ESD) is adjusted to the thickness of the patient's specific anatomy. ESD is calculated from the estimated KERMA greatness in the air. Beer-Lambert equations derived from power data mass absorption coefficients obtained from the NIST / USA, were developed for each tissue: bone, muscle, fat and skin. Skin thickness was set at 2 mm and the bone was estimated in the central ray of the site, in the anteroposterior view. Because they are similar in density and attenuation coefficients, muscle and fat are treated as a single tissue. For evaluation of the full equations, we chose three different anatomies: chest, hand and thigh. Although complex in its shape, the equations simplify direct determination of absorbed dose from the characteristics of the equipment and patient. The input data is inserted at a single time and total absorbed dose (mGy) is calculated instantly. The average error, when compared with available data, is less than 5% in any combination of device data and exams. In calculating the dose for an exam and patient, the operator can choose the variables that will deposit less radiation to the patient through the prior analysis of each combination of variables, using the ALARA principle in routine diagnostic radiology sector.

  8. DETERMINATION OF SUPERFICIAL ABSORBED DOSE FROM EXTERNAL EXPOSURE OF WEAKLY PENETRATING RADIATIONS

    Institute of Scientific and Technical Information of China (English)

    陈丽姝

    1994-01-01

    The methods of determining the superficial absorbed dose distributions in a water phantom by means of the experiments and available theories have been reported.The distributions of beta dose were measured by an extrapolation ionization chamber at definite depthes corresponding to some superficial organs and tissues such as the radiosensitive layer of the skin,cornea,sclera,anterior chamber and lens of eyeball.The ratios among superficial absorbed dose D(0.07) and average absorbed doses at the depthes 1,2,3,4,5 and 6mm are also obtained with Cross's methods.They can be used for confining the deterministic effects of some superficial tissues and organs such as the skin and the components of eyeball for weakly penetrating radiations.

  9. Evaluation of the distribution of absorbed dose in child phantoms exposed to diagnostic medical x rays

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W. L.; Poston, J. W.; Warner, G. G.

    1978-04-01

    The purpose of this study was to determine, by theoretical calculation and experimental measurement, the absorbed dose distributions in two heterogeneous phantoms representing one-year- and five-year-old children from typical radiographic examinations for those ages. Theoretical work included the modification of an existing internal dose code which uses Monte Carlo methods to determine doses within the Snyder-Fisher mathematical phantom. A Ge(Li) detector and a pinhole collimator were used to measure x-ray spectra which served as input to the modified Monte Carlo codes which were used to calculate organ doses in children. The calculated and measured tissue-air values were compared for a number of organs. For most organs, the results of the calculated absorbed doses agreed with the measured absorbed doses within twice the coefficient of variation of the calculated value. The absorbed dose to specific organs for several selected radiological examinations are given for one-year-old, five-year-old, and adult phantoms.

  10. Absorbed Doses to Patients in Nuclear Medicine; Doskatalogen foer nukleaermedicin

    Energy Technology Data Exchange (ETDEWEB)

    Leide-Svegborn, Sigrid; Mattsson, Soeren; Johansson, Lennart; Fernlund, Per; Nosslin, Bertil

    2007-04-15

    The Swedish radiation protection authority, (SSI), has supported work on estimates of radiation doses to patients from nuclear medicine examinations since more than 20 years. A number of projects have been reported. The results are put together and published under the name 'Doskatalogen' which contains data on doses to different organs and tissues from radiopharmaceuticals used for diagnostics and research. This new report contains data on: {sup 11}C-labelled substances (realistic maximum model), amino acids labelled with {sup 11}C, {sup 18}F or {sup 75}Se, {sup 99m}Tc-apcitide, {sup 123}I-labelled fatty acids ({sup 123}I- BMIPP and {sup 123}I-IPPA) and revised models for previously reported {sup 15}O-labelled water, {sup 99m}Tc-tetrofosmin (rest as well as exercise) and {sup 201}Tl-ion Data for almost 200 substances and radionuclides are included in the 'Doskatalogen' today. Since the year 2001 the 'Doskatalogen' is available on the authority's home page (www.ssi.se)

  11. Absorbed dose and dose rate using the Varian OBI 1.3 and 1.4 CBCT system.

    Science.gov (United States)

    Palm, Asa; Nilsson, Elisabeth; Herrnsdorf, Lars

    2010-01-28

    According to published data, the absorbed dose used for a CBCT image acquisition with Varian OBI v1.3 can be as high as 100 mGy. In 2008 Varian released a new OBI version (v1.4), which promised to reduce the imaging dose. In this study, absorbed doses used for CBCT image acquisitions with the default irradiation techniques of Varian OBI v1.3 and v1.4 are measured. TLDs are used to derive dose distributions at three planes inside an anthropomorphic phantom. In addition, point doses and dose profiles inside a 'stack' of three CTDI body phantoms are measured using a new solid state detector, the CT Dose Profiler. With the CT Dose Profiler, the individual pulses from the X-ray tube are also studied. To verify the absorbed dose measured with the CT Dose Profiler, it is compared to TLD. The image quality is evaluated using a Catphan phantom. For OBI v1.3, doses measured in transverse planes of the Alderson phantom range between 64 mGy and 144 mGy. The average dose is around 100 mGy. For OBI v1.4, doses measured in transverse planes of the Alderson phantom range between 1 mGy and 51 mGy. Mean doses range between 3-35 mGy depending on CBCT mode. CT Dose Profiler data agree with TLD measurements in a CTDI phantom within the uncertainty of the TLD measurements (estimated SD +/- 10%). Instantaneous dose rate at the periphery of the phantom can be higher than 20 mGy/s, which is 10 times the dose rate at the center. The spatial resolution in v1.4 is not as high as in v1.3. In conclusion, measurements show that the imaging doses for default modes in Varian OBI v1.4 CBCT system are significantly lower than in v1.3. The CT Dose Profiler is proven fast and accurate for CBCT applications.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  14. The 1997 determination of the Australian standards of exposure and absorbed dose at {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Huntley, R.B.; Boas, J.F. [Australian Radiation Laboratory, Yallambie, VIC (Australia); Van der Gaast, H. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1998-05-01

    The arrangements for the maintenance of the Australian standards for {sup 60}Co are described in detail. The primary standards are a graphite cavity chamber for exposure/air kerma and a graphite calorimeter for absorbed dose. These secondary standards are described and their responses in corresponding {sup 90}Sr reference sources are reported. Accurate ratios between the Australian Radiation Laboratory (ARL) and Australian Nuclear Science and Technology (ANSTO) {sup 90}Sr reference sources are derived for use in future calibrations. The value of 28.8 years for the half-life of {sup 90}Sr is confirmed. The usefulness of {sup 90}Sr reference source measurements in quality assurance is discussed. The charge sensitivity and linearity of the ANSTO electrometers are reported by two different methods and are compared with previous results. Calibration factors for all the secondary standard ionization chambers are given, in terms of exposure, air kerma and absorbed dose to water. Calibration factors are also given for most of the chambers in terms of absorbed dose to graphite. The methods of deriving the calibration factors are explained in detail, including all the corrections applied to both the primary and secondary standard measurements. Three alternative methods of deriving the absorbed dose to water calibration factors are compared. The reported calibration factors are compared with previous results. Changes in the Australian units of exposure, air kerma and absorbed dose to graphite and water are derived from changes in the corresponding calibration factors. The Australian units of exposure and air kerma have not changed significantly since 1990. The Australian unit of absorbed dose to graphite is now 1.1 % smaller than in 1993 and 1.3 % smaller than in 1990. The Australian unit of absorbed dose to water is now 1.4 % smaller than in 1993, but is only 0.9 % smaller than in 1990. Comparisons of the Australian standards of exposure/air kerma and absorbed dose with

  15. Dose determination with nitro blue tetrazolium containing radiochromic dye films by measuring absorbed and reflected light

    DEFF Research Database (Denmark)

    Kovács, A.; Baranyai, M.; Wojnárovits, L.

    2000-01-01

    Tetrazolium salts as heterocyclic organic compounds are known to form highly coloured, water insoluble formazans by reduction, which can be utilized in radiation processing dosimetry. Radiochromic films containing nitro blue tetrazolium dissolved in a polymer matrix were found suitable for dose...... determination in a wide dose range both by absorbance and reflectance measurements. The concept of measuring reflected light from dose labels has been discussed earlier and emerged recently due to the requirement of introducing semiquantitative label dose indicators for quarantine control. The usefulness...

  16. Estimation of eye absorbed doses in head & neck radiotherapy practices using thermoluminescent detectors

    Directory of Open Access Journals (Sweden)

    Gh Bagheri

    2011-09-01

    Full Text Available  Determination of eye absorbed dose during head & neck radiotherapy is essential to estimate the risk of cataract. Dose measurements were made in 20 head & neck cancer patients undergoing 60Co radiotherapy using LiF(MCP thermoluminescent dosimeters. Head & neck cancer radiotherapy was delivered by fields using SAD & SSD techniques. For each patient, 3 TLD chips were placed on each eye. Head & neck dose was about 700-6000 cGy in 8-28 equal fractions. The range of eye dose is estimated to be (3.49-639.1 mGy with a mean of maximum dose (98.114 mGy, which is about 3 % of head & neck dose. Maximum eye dose was observed for distsnces of about 3 cm from edge of the field to eye.

  17. Evaluation of bismuth shielding effectiveness in reducing breast absorbed dose during thoracic CT scan

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, T. C.; Mourao, A. P.; Santana, P. C.; Silva, T. A. [Federal University of Minas Gerais, Program of Nuclear Science and Techniques, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    Computed Tomography (CT) is an essential method for tracking neoplasia and efficiently diagnosing a wide variety of thoracic diseases. CT is generally considered the most accurate choice for lung examination. Due to the growing use of CT, breast and other superficial and radiosensitive organs are unnecessarily irradiated during radiological procedures, thus requiring the development of strategies appropriate to optimize and, if possible, to reduce the radiation dose. The use of bismuth shielding to reduce radiation dose absorbed by breast during thoracic CT examinations has been the subject of many studies recently published by Brazilian and foreign authors of various fields. The purpose of this paper is both to accurately determine the glandular dose when breast is exposed to radiation and to assess the reduction in absorbed dose during thoracic CT examinations, using a set of Thermoluminescent Dosimeters, an anthropomorphic phantom and bismuth shielding. (Author)

  18. Radiation-Induced Color Centers in LiF for Dosimetry at High Absorbed Dose Rates

    DEFF Research Database (Denmark)

    McLaughlin, W. L.; Miller, Arne; Ellis, S. C.

    1980-01-01

    Color centers formed by irradiation of optically clear crystals of pure LiF may be analyzed spectrophotometrically for dosimetry in the absorbed dose range from 102 to 107 Gy. Routine monitoring of intense electron beams is an important application. Both 6LiF and 7LiF forms are commercially avail...... available, and when used with filters as albedo dosimeters in pairs, they provide discrimination of neutron and gamma-ray doses....

  19. Determination of Absorbed dose of patients organs under kidney Scintigraphy by using the MIRD Dosimetry method

    Directory of Open Access Journals (Sweden)

    Shokofeh Pirdomooie

    2016-07-01

    13±0.66, 2.1±0.24, 2.2±0.38, 335.43±3.3 mrad/mCi respectively. Conclusion: in this study, Bladder and liver received highest and lowest absorbed doses respectively. Also, the results of this study, showed good agreement with ICRP no.106 report.

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

    Science.gov (United States)

    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.

  1. Measurement of absorbed dose with a bone-equivalent extrapolation chamber.

    Science.gov (United States)

    DeBlois, François; Abdel-Rahman, Wamied; Seuntjens, Jan P; Podgorsak, Ervin B

    2002-03-01

    A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water and bone-equivalent material was used for determining absorbed dose in a bone-equivalent phantom irradiated with clinical radiation beams (cobalt-60 gamma rays; 6 and 18 MV x rays; and 9 and 15 MeV electrons). The dose was determined with the Spencer-Attix cavity theory, using ionization gradient measurements and an indirect determination of the chamber air-mass through measurements of chamber capacitance. The collected charge was corrected for ionic recombination and diffusion in the chamber air volume following the standard two-voltage technique. Due to the hybrid chamber design, correction factors accounting for scatter deficit and electrode composition were determined and applied in the dose equation to obtain absorbed dose in bone for the equivalent homogeneous bone phantom. Correction factors for graphite electrodes were calculated with Monte Carlo techniques and the calculated results were verified through relative air cavity dose measurements for three different polarizing electrode materials: graphite, steel, and brass in conjunction with a graphite collecting electrode. Scatter deficit, due mainly to loss of lateral scatter in the hybrid chamber, reduces the dose to the air cavity in the hybrid PEEC in comparison with full bone PEEC by 0.7% to approximately 2% depending on beam quality and energy. In megavoltage photon and electron beams, graphite electrodes do not affect the dose measurement in the Solid Water PEEC but decrease the cavity dose by up to 5% in the bone-equivalent PEEC even for very thin graphite electrodes (<0.0025 cm). In conjunction with appropriate correction factors determined with Monte Carlo techniques, the uncalibrated hybrid PEEC can be used for measuring absorbed dose in bone material to within 2% for high-energy photon and electron beams.

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

    Science.gov (United States)

    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.

  3. Fetus absorbed dose evaluation in head and neck radiotherapy procedures of pregnant patients

    Energy Technology Data Exchange (ETDEWEB)

    Camargo da C, E.; Ribeiro da R, L. A.; Santos B, D. V., E-mail: etieli@ird.gov.br [Instituto de Radioprotecao e Dosimetria / CNEN, Av. Salvador Allende s/n, Barra de Tijuca, 22783-127 Rio de Janeiro (Brazil)

    2014-08-15

    Each year a considerable amount of pregnant women needs to be submitted to radiotherapeutic procedures to combat malignant tumors. Radiation therapy is often a treatment of choice for these patients. It is possible to use shielding and beam positioning such that the potential dose to the fetus can be minimized. In this work the head and neck cancer treatment of a pregnant patient was experimentally simulated. The patient was simulated by an anthropomorphic Alderson phantom and the absorbed dose to the fetus was evaluated using micro-rod TLD-100 detectors in two conditions, namely protecting the patients abdomen with a 7 cm lead layer and using no abdomen shielding. The aim of this experiment was to evaluate the efficiency of the abdomen protection in reducing the fetus absorbed dose. Irradiations were performed with a Trilogy linear accelerator using x-rays of 6 MV. A total dose of 50 Gy to the target volume was delivered. The fetus doses evaluated with and without the lead shielding were, respectively, 0.52±0.039 and (0.88±0.052) c Gy, corresponding to a dose reduction of 59%. The dose (0.52±0.039) c Gy is within the zone of biological tolerance for the fetus. (Author)

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Willegaignon, J., E-mail: j.willegaignon@gmail.com; Sapienza, M. T.; Coura-Filho, G. B.; Buchpiguel, C. A. [Cancer Institute of São Paulo State (ICESP), Clinical Hospital, School of Medicine, University of São Paulo, São Paulo 01246-000 (Brazil); Nuclear Medicine Service, Department of Radiology, School of Medicine, University of São Paulo, Sao Paulo 01246-000 (Brazil); Watanabe, T. [Nuclear Medicine Service, Department of Radiology, School of Medicine, University of São Paulo, São Paulo 01246-000 (Brazil); Traino, A. C. [Unit of Medical Physics, Azienda Ospedaliero-Universitaria Pisana, Pisa 56126 (Italy)

    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

  6. Absorbed dose by thyroid in case of nuclear accidents; Dose absorvida pela tireoide em casos de acidentes nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Laelia; Attie, Marcia Regina Pereira [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Fisica; Lima, Fernando Roberto de Andrade, E-mail: falima@cnen.gov.b [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Amaral, Ademir [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2011-07-01

    Radioisotopes of iodine are produced in abundance in nuclear fission reactions, and great amounts of radioiodine may be released into the environment in case of a nuclear reactor accident. Thyroid gland is among the most radiosensitive organs due to its capacity to concentrate iodine. The aim of this work was to evaluate the importance of contributions of internally deposited iodines ({sup 131}I, {sup 132}I, {sup 133}I, {sup 134}I and {sup 135}I) to the dose absorbed to thyroid follicle and to the whole organ, after internal contamination by those isotopes. For internal dose calculation, the code of particles transport MCNP4C was employed. The results showed that, in case of nuclear accidents, the contribution of short-lived iodines for total dose is about 45% for thyroid of newborn and about 40% for thyroid of adult. Thus, these contributions should not be neglected in a prospective evaluation of risks associated to internal contamination by radioactive iodine. (author)

  7. Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom

    CERN Document Server

    Job, P K; Semones, E

    1999-01-01

    High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mmx300 mmx300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cro...

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

    Science.gov (United States)

    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.

  9. Standard Guide for Absorbed-Dose Mapping in Radiation Processing Facilities

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This document provides guidance in determining absorbed-dose distributions in products, materials or substances irradiated in gamma, X-ray (bremsstrahlung) and electron beam facilities. Note 1—For irradiation of food and the radiation sterilization of health care products, other specific ISO and ISO/ASTM standards containing dose mapping requirements exist. For food irradiation, see ISO/ASTM 51204, Practice for Dosimetry in Gamma Irradiation Facilities for Food Processing and ISO/ASTM 51431, Practice for Dosimetry in Electron and Bremsstrahlung Irradiation Facilities for Food Processing. For the radiation sterilization of health care products, see ISO 11137: 1995, Sterilization of Health Care Products Requirements for Validation and Routine Control Radiation Sterilization. In those areas covered by ISO 11137, that standard takes precedence. ISO/ASTM Practice 51608, ISO/ASTM Practice 51649, and ISO/ASTM Practice 51702 also contain dose mapping requirements. 1.2 Methods of analyzing the dose map data ar...

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Michely C. da [FFCLRP, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Sampaio, Francisco G.A., E-mail: francisampaio@pg.ffclrp.usp.br [FFCLRP, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Petchevist, Paulo C.D., E-mail: petchevist12@yahoo.com.br [FFCLRP, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Instituto de Radioterapia e Megavoltagem, Ribeirao Preto, Sao Paulo (Brazil); Oliveira, Andre L. de [Servico de Radioterapia do Hospital das Clinicas da Unicamp, Campinas, Sao Paulo (Brazil); Almeida, Adelaide de, E-mail: dalmeida@ffclrp.usp.br [FFCLRP, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil)

    2011-12-15

    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.

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

    Science.gov (United States)

    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.

  13. Utilization of radiation protection gear for absorbed dose reduction: an integrative literature review

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Flavio Augusto Penna; Flor, Rita de Cassia [Instituto Federal de Santa Catarina (IFSC), Florianopolis, SC (Brazil); Pereira, Aline Garcia, E-mail: aalinegp@gmail.co [Sinan Project - Sistema de Informacao de Agravos de Notificacao, Florianopolis, SC (Brazil)

    2011-03-15

    Objective: The present study was aimed at evaluating the relation between the use of radiation protection gear and the decrease in absorbed dose of ionizing radiation, thereby reinforcing the efficacy of its use by both the patients and occupationally exposed personnel. Materials and Methods: The integrative literature review method was utilized to analyze 21 articles, 2 books, 1 thesis, 1 monograph, 1 computer program, 4 pieces of database research (Instituto Brasileiro de Geografia e Estatistica and Departamento de Informatica do Sistema Unico de Saude) and 2 sets of radiological protection guidelines. Results: Theoretically, a reduction of 86% to 99% in the absorbed dose is observed with the use of radiation protection gear. In practice, however, the reduction may achieve 88% in patients submitted to conventional radiology, and 95% in patients submitted to computed tomography. In occupationally exposed individuals, the reduction is around 90% during cardiac catheterization, and 75% during orthopedic surgery. Conclusion: According to findings of several previous pieces of research, the use of radiation protection gear is a low-cost and effective way to reduce absorbed dose both for patients and occupationally exposed individuals. Thus, its use is necessary for the implementation of effective radioprotection programs in radiodiagnosis centers. (author)

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

    Science.gov (United States)

    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.

  15. Preliminary Study on the Quantitative Value Transfer Method of Absorbed Dose to Water in 60Co γ Radiation

    Directory of Open Access Journals (Sweden)

    SONG Ming-zhe

    2015-01-01

    Full Text Available Absorbed dose to water in 60Co γ radiation is the basic physics quantity in the quantitative value system of radiation therapy, it is very necessary for radiation therapy. The study on the quantitative value transfer method of absorbed dose to water in 60Co γ Radiation could provide important technical support to the establishment of Chinese absorbed dose to water quantity system. Based on PTW-30013 ionization chamber, PMMA water phantom and 3D mobile platform, quantitative value transfer standard instrument was established, combined with the requirement of IAEA-TRS398, developed preliminary study of 60Co absorbed dose to water quantity value transfer method. After the quantity value transfer, the expanded uncertainty of absorbed dose to water calibration factor of PTW-30013 was 0.90% (k=2, the expanded uncertainty of absorbed dose to water of 60Co γ reference radiation in Radiation Metrology Center (SSDL of IAEA was 1.4% (k=2. The results showed that, this value transfer method can reduce the uncertainty of 60Co absorbed dose to water effectively in Secondary Standard Dosimetry Laboratory.

  16. Determination of Absorbed and Effective Dose from Natural Background Radiation around a Nuclear Research Facility

    Directory of Open Access Journals (Sweden)

    M. A. Musa

    2011-01-01

    Full Text Available Problem statement: This study presents result of outdoor absorbed dose rate and estimated effective dose from the naturally occurring radionuclides 232Th and 238U series 40K, around a Nuclear Research Reactor at the Centre for Energy Research and Training (CERT, Zaria, Nigeria. Approach: A high-resolution in situ ?-ray spectrometry was used to carry out the study. CERT houses a 30Kw Research Reactor and other neutron and gamma sources for Research and Training. Results: The values of absorbed dose rate in air for 232Th, 238U and 40K range from 8.2 ± 2.5-24.5 ± 3.6 nGy h?1, 1.9 ± 1.2-4.6 ± 2.5 nGy h?1 and 12.2 ± 5-38 ± 6.7n Gy h?1 respectively . The estimated total annual effective dose outdoor for the sites range from 27.3-79.9 ?Sv y?1.Conclusions: This showed that radiation exposure level for the public is lower than the recommended value of 1 mSv y?1.Hence, the extensive usage of radioactive materials within and around CERT does not appear to have any impact on the radiation burden of the environment.

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

    Energy Technology Data Exchange (ETDEWEB)

    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. (Environmental Science Division); (Westlakes Scientific Consulting Ltd.); (Inst. de Radioprotection et de Surete Nucleaire); (Centre for Ecology & Hydrology); (Norwegian Radiation Protection Authority); (State Office for Nuclear Safety); (Korea Atomic Energy Research Institute); (Visible Information Centre Inc.); (Belgian Nuclear Research Centre); (University of Liverpool)

    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.

  18. Analysis of contrast and absorbed doses in mammography; Analise de contraste e doses absorvidas em mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Augusto, F.M. [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Hospital das Clinicas. Centro de Ciencias das Imagens e Fisica Medica]. E-mail: fernando@fmrp.usp.br; Dias, T.S.K. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil); Ghilardi Netto, T.; Subtil, L.J.; Silva, R. da [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica

    2001-07-01

    One of the great causes of mortality between women in the world is the breast cancer. The mammograms are the method most efficient to detect some cases of cancer of breast before this to be clinically concrete. The quality of a picture system must be determined by the ability to detect tissue soft masses, cyst or tumors, but also calcifications. This detection is directly connected with the contrast obtained in these pictures. This work has for objective to develop a method for the analysis of this contrast in mammograms verifying the doses referred to these mammograms and comparing them with national and international levels of reference. (author)

  19. Studies of the sensitivity dependence of float zone silicon diodes on gamma absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Pascoalino, K.C.S.; Santos, T.C. dos; Barbosa, R.F.; Camargo, F. de; Goncalves, J.A.C.; Bueno, C.C. [Instituto de Pesquisas Energeticas e Nucleares (CTR/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Tecnologia das Radiacoes

    2011-07-01

    Full text: Several advantages of silicon diodes which include small size, low cost, high sensitivity and wide availability, make them suitable for dosimetry and for radiation field mapping. However, the small radiation tolerance of ordinary silicon devices has imposed constraints on their application in intense radiation fields such as found in industrial radiation processes. This scenario has been changed with the development of radiation hard silicon devices to be used as track detectors in high-energy physics experiments. Particularly, in this work it is presented the dosimetric results obtained with a batch of nine junction silicon diodes developed, in the framework of CERN RD50 Collaboration, as good candidates for improved radiation hardness. These diodes were produced with 300 micrometer n-type silicon substrate grown by standard float zone technique and processed by the Microelectronics Center of Helsinki University of Technology. The samples irradiation was performed using a Co-60 irradiator (Gammacell 220) which delivers a dose-rate of 2 kGy/h. During the irradiation, the unbiased diodes were connected through low-noise coaxial cables to the input of a KEITHLEY 617 electrometer, in order to monitor the devices photocurrent as a function of the exposure time. To study the response uniformity of the batch of nine diodes as well the sensitivity dependence on the absorbed dose, they were irradiated with different doses from 5 kGy up to 50 kGy. The sensitivity response of each device was investigated through the on-line measurements of the current signals as a function of the exposure time. For doses up to 5 kGy, all diodes exhibited a current decay of almost six percent in comparison with the value registered at the start-time of the irradiation. However, this decrease in the current sensitivity is much smaller than those observed with ordinary diodes for the same absorbed dose. The dose-response curves of the devices were also investigated through the plot

  20. Calculation of absorbed doses to water pools in severe accident sequences

    Energy Technology Data Exchange (ETDEWEB)

    Weber, C.F. [Oak Ridge National Lab., TN (United States)

    1991-12-01

    A methodology is presented for calculating the radiation dose to a water pool from the decay of uniformly distributed nuclides in that pool. Motivated by the need to accurately model radiolysis reactions of iodine, direct application is made to fission product sources dissolved or suspended in containment sumps or pools during a severe nuclear reactor accident. Two methods of calculating gamma absorption are discussed - one based on point-kernal integration and the other based on Monte Carlo techniques. Using least-squares minimization, the computed results are used to obtain a correlation that relates absorbed dose to source energy and surface-to-volume ratio of the pool. This correlation is applied to most relevant fission product nuclides and used to actually calculate transient sump dose rate in a pressurized-water reactor (PWR) severe accident sequence.

  1. Dose evaluation of therapeutic radiolabeled bleomycin complexes based on biodistribution data in wild-type rats:Effect of radionuclides in absorbed dose of different organs

    Institute of Scientific and Technical Information of China (English)

    Hassan Yousefnia; Samaneh Zolghadri; Amir Reza Jalilian; Mohammad Ghannadi-Maragheh

    2015-01-01

    Bleomycins (BLMs), as tumor-seeking antibiotics, have been used for over 20 years in treatment of several types of cancers. Several radioisotopes are used in radiolabeling of BLMs for therapeutic and diagnostic purpos-es. An important points in developing new radiopharmaceuticals, especially therapeutic agents, is the absorbed dose delivered in critical organs. In this work, absorbed dose to organs after injection of 153Sm-, 177Lu-and 166Ho-labeled BLM was investigated by radiation dose assessment resource (RADAR) method based on biodis-tribution data in wild-type rats. The absorbed dose effect of the radionuclides was evaluated. The maximum absorbed dose for the complexes was observed in the kidneys, liver and lungs. For all the radiolabeled BLMs, bone and red marrow received considerable absorbed dose. Due to the high energy beta particles emitted by 166Ho, higher absorbed dose is observed for 166Ho-BLM in the most organs. The reported data can be useful for the determination of the maximum permissible injected activity of the radiolabeled BLMs in the treatment planning programs.

  2. Radioiodine Therapy of Hyperthyroidism. Simplified patient-specific absorbed dose planning

    Energy Technology Data Exchange (ETDEWEB)

    Joensson, Helene

    2003-10-01

    Radioiodine therapy of hyperthyroidism is the most frequently performed radiopharmaceutical therapy. To calculate the activity of {sup 131}I to be administered for giving a certain absorbed dose to the thyroid, the mass of the thyroid and the individual biokinetic data, normally in the form of uptake and biologic half-time, have to be determined. The biologic half-time is estimated from several uptake measurements and the first one is usually made 24 hours after the intake of the test activity. However, many hospitals consider it time-consuming since at least three visits of the patient to the hospital are required (administration of test activity, first uptake measurement, second uptake measurement plus treatment). Instead, many hospitals use a fixed effective half-time or even a fixed administered activity, only requiring two visits. However, none of these methods considers the absorbed dose to the thyroid of the individual patient. In this work a simplified patient-specific method for treating hyperthyroidism is proposed, based on one single uptake measurement, thus requiring only two visits to the hospital. The calculation is as accurate as using the individual biokinetic data. The simplified method is as patient-convenient and time effective as using a fixed effective half-time or a fixed administered activity. The simplified method is based upon a linear relation between the late uptake measurement 4-7 days after intake of the test activity and the product of the extrapolated initial uptake and the effective half-time. Treatments not considering individual biokinetics in the thyroid result in a distribution of administered absorbed dose to the thyroid, with a range of -50 % to +160 % compared to a protocol calculating the absorbed dose to the thyroid of the individual patient. Treatments with a fixed administered activity of 370 MBq will in general administer 250 % higher activity to the patient, with a range of -30 % to +770 %. The absorbed dose to other

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

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Perry B; Bahadori, Amir A [Nuclear and Radiological Engineering, University of Florida, Gainesville, FL 32611 (United States); Eckerman, Keith F [Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Lee, Choonsik [Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892 (United States); Bolch, Wesley E, E-mail: wbolch@ufl.edu [Nuclear and Radiological/Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2011-04-21

    A comprehensive set of photon fluence-to-dose response functions (DRFs) is presented for two radiosensitive skeletal tissues-active and total shallow marrow-within 15 and 32 bone sites, respectively, of the ICRP reference adult male. The functions were developed using fractional skeletal masses and associated electron-absorbed fractions as reported for the UF hybrid adult male phantom, which in turn is based upon micro-CT images of trabecular spongiosa taken from a 40 year male cadaver. The new DRFs expand upon both the original set of seven functions produced in 1985, and a 2007 update calculated under the assumption of secondary electron escape from spongiosa. In this study, it is assumed that photon irradiation of the skeleton will yield charged particle equilibrium across all spongiosa regions at energies exceeding 200 keV. Kerma coefficients for active marrow, inactive marrow, trabecular bone and spongiosa at higher energies are calculated using the DRF algorithm setting the electron-absorbed fraction for self-irradiation to unity. By comparing kerma coefficients and DRF functions, dose enhancement factors and mass energy-absorption coefficient (MEAC) ratios for active marrow to spongiosa were derived. These MEAC ratios compared well with those provided by the NIST Physical Reference Data Library (mean difference of 0.8%), and the dose enhancement factors for active marrow compared favorably with values calculated in the well-known study published by King and Spiers (1985 Br. J. Radiol. 58 345-56) (mean absolute difference of 1.9 percentage points). Additionally, dose enhancement factors for active marrow were shown to correlate well with the shallow marrow volume fraction (R{sup 2} = 0.91). Dose enhancement factors for the total shallow marrow were also calculated for 32 bone sites representing the first such derivation for this target tissue.

  4. Uncertainties in electron-absorbed fractions and lung doses from inhaled beta-emitters.

    Science.gov (United States)

    Farfán, Eduardo B; Bolch, Wesley E; Huston, Thomas E; Rajon, Didier A; Huh, Chulhaeng; Bolch, W Emmett

    2005-01-01

    The computer code LUDUC (Lung Dose Uncertainty Code), developed at the University of Florida, was originally used to investigate the range of potential doses from the inhalation of either plutonium or uranium oxides. The code employs the ICRP Publication 66 Human Respiratory Tract model; however, rather than using simple point estimates for each of the model parameters associated with particle deposition, clearance, and lung-tissue dosimetry, probability density functions are ascribed to these parameters based upon detailed literature review. These distributions are subsequently sampled within LUDUC using Latin hypercube sampling techniques to generate multiple (e.g., approximately 1,000) sets of input vectors (i.e., trials), each yielding a unique estimate of lung dose. In the present study, the dosimetry component of the ICRP-66 model within LUDUC has been extended to explicitly consider variations in the beta particle absorbed fraction due to corresponding uncertainties and biological variabilities in both source and target tissue depths and thicknesses within the bronchi and bronchioles of the thoracic airways. Example dose distributions are given for the inhalation of absorption Type S compounds of 90Sr (Tmax = 546 keV) and 90Y (Tmax = 2,284 keV) as a function of particle size. Over the particle size range of 0.001 to 1 microm, estimates of total lung dose vary by a factor of 10 for 90Sr particles and by a factor of 4 to 10 for 90Y particles. As the particle size increases to 10 microm, dose uncertainties reach a factor of 100 for both radionuclides. In comparisons to identical exposures scenarios run by the LUDEP 2.0 code, Reference Man doses for inhaled beta-emitters were shown to provide slightly conservative estimates of lung dose compared to those in this study where uncertainties in lung airway histology are considered.

  5. FLUKA predictions of the absorbed dose in the HCAL Endcap scintillators using a Run1 (2012) CMS FLUKA model

    CERN Document Server

    CMS Collaboration

    2016-01-01

    Estimates of absorbed dose in HCAL Endcap (HE) region as predicted by FLUKA Monte Carlo code. Dose is calculated in an R-phi-Z grid overlaying HE region, with resolution 1cm in R, 1mm in Z, and a single 360 degree bin in phi. This allows calculation of absorbed dose within a single 4mm thick scintillator layer without including other regions or materials. This note shows estimates of the cumulative dose in scintillator layers 1 and 7 during the 2012 run.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. Boundary electron and beta dosimetry-quantification of the effects of dissimilar media on absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, J.C.

    1991-01-01

    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 radiommunotherapy 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 had 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 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 are compared with experimental data. Monte Carlo results compare satisfactory with experimental results for the boundaries considered.

  10. Determination of Radiation Absorbed Dose to Primary Liver Tumors and Normal Liver Tissue Using Post Radioembolization 90Y PET

    Directory of Open Access Journals (Sweden)

    Shyam Mohan Srinivas

    2014-10-01

    Full Text Available Background: Radioembolization with Yttrium-90 (90Y microspheres is becoming a more widely used transcatheter treatment for unresectable hepatocellular carcinoma (HCC. Using post-treatment 90Y PET/CT scans,the distribution of microspheres within the liver can be determined and quantitatively assessesed . We studied the radiation dose of 90Y delivered to liver and treated tumors.Methods: This retrospective study of 56 patients with HCC, including analysis of 98 liver tumors, measured and correlated the dose of radiation delivered to liver tumors and normal liver tissue using glass microspheres (TheraSpheres® to the frequency of complications with mRECIST. 90Y PET/CT and triphasic liver CT scans were used to contour treated tumor and normal liver regions and determine their respective activity concentrations. An absorbed dose factor was used to convert the measured activity concentration (Bq/mL to an absorbed dose (Gy.Results: The 98 studied tumors received a mean dose of 169 Gy (mode 90-120 Gy;range 0-570 Gy. Tumor response by mRECIST criteria was performed for 48 tumors that had follow up scans. There were 21 responders (mean dose 215 Gy and 27 nonresponders (mean dose 167 Gy. The association between mean tumor absorbed dose and response suggests a trend but did not reach statistical significance (p=0.099. Normal liver tissue received a mean dose of 67 Gy (mode 60-70 Gy; range 10-120 Gy. There was a statistically significant association between absorbed dose to normal liver and the presence of two or more severe complications (p=0.036.Conclusion: Our cohort of patients showed a possible dose response trend for the tumors. Collateral dose to normal liver is nontrivial and can have clinical implications. These methods help us understand whether patient adverse events, treatment success, or treatment failure can be attributed to the dose which the tumor or normal liver received.

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

    Science.gov (United States)

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

    2015-10-01

    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

  12. Spatial accuracy of 3D reconstructed radioluminographs of serial tissue sections and resultant absorbed dose estimates

    Energy Technology Data Exchange (ETDEWEB)

    Petrie, I.A.; Flynn, A.A.; Pedley, R.B.; Green, A.J.; El-Emir, E.; Dearling, J.L.J.; Boxer, G.M.; Boden, R.; Begent, R.H.J. [Cancer Research UK Targeting and Imaging Group, Department of Oncology, Royal Free and University College Medical School, Royal Free Campus, London (United Kingdom)

    2002-10-21

    Many agents using tumour-associated characteristics are deposited heterogeneously within tumour tissue. Consequently, tumour heterogeneity should be addressed when obtaining information on tumour biology or relating absorbed radiation dose to biological effect. We present a technique that enables radioluminographs of serial tumour sections to be reconstructed using automated computerized techniques, resulting in a three-dimensional map of the dose-rate distribution of a radiolabelled antibody. The purpose of this study is to assess the reconstruction accuracy. Furthermore, we estimate the potential error resulting from registration misalignment, for a range of beta-emitting radionuclides. We compare the actual dose-rate distribution with that obtained from the same activity distribution but with manually defined translational and rotational shifts. As expected, the error produced with the short-range {sup 14}C is much larger than that for the longer range {sup 90}Y; similarly values for the medium range {sup 131}I are between the two. Thus, the impact of registration inaccuracies is greater for short-range sources. (author)

  13. Measurements of spatial distribution of absorbed dose in proton therapy with Gafchromic EBT3

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Regazzoni, V.; Grisotto, S.; Artuso, E.; Giove, D. [Universita degli Studi di Milano, Department of Physics, via Celoria 16, 20133 Milano (Italy); Borroni, M.; Carrara, M.; Pignoli, E. [Fondazione IRCCS, Istituto Nazionale dei Tumori di Milano, Medical Physics Unit, via Giacomo Venezian 16, 20133 Milano (Italy); Mirandola, A.; Ciocca, M., E-mail: grazia.gambarini@mi.infn.it [Centro Nazionale Adroterapia Oncologica, Medical Physics Unit, Strada Campeggi 53, 27100 Pavia (Italy)

    2014-08-15

    A study of the response of EBT3 films has been carried out. Light transmittance images (around 630 nm) were acquired by means of a Ccd camera. The difference of optical density was assumed as dosimeter response. Calibration was performed by means of {sup 60}Co photons, at a radiotherapy facility. A study of the response variation during the time after exposure has been carried out. EBT3 films were exposed, in a solid-water phantom, to proton beams of various energies and the obtained depth-dose profiles were compared with those measured with a ionization chamber. As expected, in the Bragg peak region the values obtained with EBT3 films were lower than those obtained with the ionization chamber. The ratio of such values was evaluated, along dose profiles, for each utilized energy. A method for correcting the data measured with EBT3 has been proposed and tested. The results confirm that the method can be advantageously applied for obtaining spatial distribution of the absorbed dose in proton therapy. (author)

  14. A feasibility study of Fricke dosimetry as an absorbed dose to water standard for 192Ir HDR sources.

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo deAlmeida

    Full Text Available 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.

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

    Science.gov (United States)

    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

  16. Absorbed dose distributions in a tissue-equivalent absorber for Bremsstrahlung produced at the beamlines of the European Synchrotron Radiation Facility

    CERN Document Server

    Pisharody, M; Berkvens, P; Colomp, P

    2000-01-01

    The absorbed-dose distributions for Bremsstrahlung, incident on a tissue-equivalent phantom, were measured with LiF : Mg,Ti thermoluminescent dosimeters at two insertion device beamlines of the European Synchrotron Radiation Facility (ESRF). The measurements were carried out for two different electron beam energies of 4 and 6 GeV. The corresponding Bremsstrahlung spectra and power were measured using a high-resolution lead glass total absorption calorimeter. The results are compared with similar measurements carried out at other facilities. The normalized Bremsstrahlung absorbed dose in a cross-sectional area of 100 mm sup sup 2 , at a depth of 150 mm of the phantom, was measured as 6.1 and 3.6 kGy h sup sup - sup sup 1 W sup sup - sup sup 1 for the corresponding Bremsstrahlung spectra of 4 and 6 GeV.

  17. Concentration activities of natural radionuclides in three fish species in Brazilian coast and their contributions to the absorbed doses

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de S.; Py Junior, Delcy de A., E-mail: wspereira@inb.gov.b, E-mail: delcy@inb.gov.b [Industrias Nucleares do Brasil SA, Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerios. Coordenacao de Protecao Radiologica; Kelecom, Alphonse, E-mail: kelecom@uol.com.b [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Curso de Pos-Graduacao em Biologia Marinha

    2009-07-01

    Activity concentrations of U-238, Ra-226, Pb-210, Th-232 e Ra-228 were analysed in three fish species at the Brasilian Coast. The fish 'Cubera snapper' (Lutjanus cyanopterus, Cuvier, 1828), in the region of Ceara and 'Whitemouth croaker' (Micropogonias furnieri, Desmarest, 1823) and 'Lebranche mullet' (Mugil liza, Valenciennes, 1836) in the region of Rio de Janeiro. These concentrations were transformed in absorbed dose rate using a dose conversion factor in unit of gray per year (muGy y{sup -1}), per becquerel per kilogram (Bq kg{sup -1}). Only the absorbed dose due to intake of radionuclides was examined, and the contributions due to radionuclides present in water and sediment were disregarded. The radionuclides were considered to be uniformly distributed in the fish body. The limit of the dose rate used, proposed by the Department of Energy of the USA, is equal to 3.65 10{sup 03} mGy y{sup -1}. The average dose rate due to the studied radionuclides is equal to 6.09 10{sup 00} muGy y{sup -1}, a value minor than 0.1% than the limits indicated by DOE, and quite similar to that found in the literature for 'benthic' fish. The most important radionuclides were the alpha emitters Ra-226 having 61 % of absorbed dose rate. U-238 and Th-232, each contributes with approximately 20 % of the absorbed dose rate. These three radionuclides are responsible for almost 100% of the dose rate received by the studied organisms. The beta emitters Ra-228 and Pb-210 account for approximately 1 % of the absorbed dose rate. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Martinez, E; Malin, M; DeWerd, L [University of WI-Madison/ADCL, Madison, WI (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  1. Decomposition of the absorbed dose by LET in tissue-equivalent materials within the SHIELD-HIT transport code

    CERN Document Server

    Sobolevsky, N; Buyukcizmeci, N; Ergun, A; Latysheva, L; Ogul, R

    2015-01-01

    The SHIELD-HIT transport code, in several versions, has been used for modeling the interaction of therapeutic beams of light nuclei with tissue-equivalent materials for a long time. All versions of the code include useful option of decomposition of the absorbed dose by the linear energy transfer (LET), but this option has not been described and published so far. In this work the procedure of decomposition of the absorbed dose by LET is described and illustrated by using the decomposition of the Bragg curve in water phantom, irradiated by beams of protons, alpha particles, and of ions lithium, carbon and oxygen.

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

    Directory of Open Access Journals (Sweden)

    Nils Rudqvist

    Full Text Available 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.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 1.5, and p-value <0.05, respectively.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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bahadori, Amir A; Johnson, Perry; Bolch, Wesley E [Department of Biomedical Engineering, University of Florida, Gainesville, FL (United States); Jokisch, Derek W [Department of Physics and Astronomy, Francis Marion University, Florence, SC (United States); Eckerman, Keith F, E-mail: wbolch@ufl.edu [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    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{sub 50}), defined as all tissues lying within the first 50 {mu}m 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{sub 50} targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM{sub 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{sub 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Reynaldo, S. R. [Development Centre of Nuclear Technology, Posgraduate Course in Science and Technology of Radiations, Minerals and Materials / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Benavente C, J. A.; Da Silva, T. A., E-mail: sirr@cdtn.br [Development Centre of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    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, metrology laboratories are required to verify the reliability of the Bss-2 system by performing additional verification measurements. In the CDTN Calibration Laboratory, the absorbed dose rates and their angular variation in the {sup 90}Sr/{sup 90}Y and {sup 85}Kr beta radiation fields were studied. Measurements were done with a 23392 model PTW extrapolation chamber and with Gafchromic radiochromic films on a PMMA slab phantom. In comparison to the certificate values provided by the Bss-2, absorbed dose rates measured with the extrapolation chamber differed from -1.4 to 2.9% for the {sup 90}Sr/{sup 90}Y and -0.3% for the {sup 85}Kr fields; their angular variation showed differences lower than 2% for incidence angles up to 40-degrees and it reached 11% for higher angles, when compared to ISO values. Measurements with the radiochromic film showed an asymmetry of the radiation field that is caused by a misalignment. Differences between the angular variations of absorbed dose rates determined by both dosimetry systems suggested that some correction factors for the extrapolation chamber that were not considered should be determined. (Author)

  5. Absorbed dose evaluation based on a computational voxel model incorporating distinct cerebral structures

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Samia de Freitas; Trindade, Bruno; Campos, Tarcisio P.R. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)]. E-mail: samiabrandao@gmail.com; bmtrindade@yahoo.com; campos@nuclear.ufmg.br

    2007-07-01

    Brain tumors are quite difficult to treat due to the collateral radiation damages produced on the patients. Despite of the improvements in the therapeutics protocols for this kind of tumor, involving surgery and radiotherapy, the failure rate is still extremely high. This fact occurs because tumors can not often be totally removed by surgery since it may produce some type of deficit in the cerebral functions. Radiotherapy is applied after the surgery, and both are palliative treatments. During radiotherapy the brain does not absorb the radiation dose in homogeneous way, because the various density and chemical composition of tissues involved. With the intention of evaluating better the harmful effects caused by radiotherapy it was developed an elaborated cerebral voxel model to be used in computational simulation of the irradiation protocols of brain tumors. This paper presents some structures function of the central nervous system and a detailed cerebral voxel model, created in the SISCODES program, considering meninges, cortex, gray matter, white matter, corpus callosum, limbic system, ventricles, hypophysis, cerebellum, brain stem and spinal cord. The irradiation protocol simulation was running in the MCNP5 code. The model was irradiated with photons beam whose spectrum simulates a linear accelerator of 6 MV. The dosimetric results were exported to SISCODES, which generated the isodose curves for the protocol. The percentage isodose curves in the brain are present in this paper. (author)

  6. Absorbed Dose in Ion Beams: Comparison of Ionization and Fluence-based Measurements

    CERN Document Server

    Osinga, Julia-Maria; Bartz, James A; Akselrod, Mark S; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    We present a direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionization chamber. Irradiations were performed at the Heidelberg Ion-Beam Therapy Center (HIT) using monoenergetic protons (142.66 MeV, 3x10^6 1/cm2) and carbon ions (270.55 MeV/u, 3x10^6 1/cm2) in the entrance channel of the ion beam. We found that absorbed dose to water values as determined by fluence measurements using FNTDs are in case of protons in good agreement (2.2 %) with ionization chamber measurements when including slower protons and Helium secondaries by an effective stopping power. For carbon, however, we found a discrepancy of 4.6 %. This deviation is significant considering both the uncertainties for ionization chambers as given in the TRS 398 and from experimental design (e.g. inhomogeneous irradiation, machine stability, beam direction). Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not seen.

  7. Calculation of Absorbed Dose in Target Tissue and Equivalent Dose in Sensitive Tissues of Patients Treated by BNCT Using MCNP4C

    Science.gov (United States)

    Zamani, M.; Kasesaz, Y.; Khalafi, H.; Pooya, S. M. Hosseini

    Boron Neutron Capture Therapy (BNCT) is used for treatment of many diseases, including brain tumors, in many medical centers. In this method, a target area (e.g., head of patient) is irradiated by some optimized and suitable neutron fields such as research nuclear reactors. Aiming at protection of healthy tissues which are located in the vicinity of irradiated tissue, and based on the ALARA principle, it is required to prevent unnecessary exposure of these vital organs. In this study, by using numerical simulation method (MCNP4C Code), the absorbed dose in target tissue and the equiavalent dose in different sensitive tissues of a patiant treated by BNCT, are calculated. For this purpose, we have used the parameters of MIRD Standard Phantom. Equiavelent dose in 11 sensitive organs, located in the vicinity of target, and total equivalent dose in whole body, have been calculated. The results show that the absorbed dose in tumor and normal tissue of brain equal to 30.35 Gy and 0.19 Gy, respectively. Also, total equivalent dose in 11 sensitive organs, other than tumor and normal tissue of brain, is equal to 14 mGy. The maximum equivalent doses in organs, other than brain and tumor, appear to the tissues of lungs and thyroid and are equal to 7.35 mSv and 3.00 mSv, respectively.

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

    Science.gov (United States)

    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. Renal function affects absorbed dose to the kidneys and haematological toxicity during {sup 177}Lu-DOTATATE treatment

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Johanna; Berg, Gertrud [Sahlgrenska University Hospital, Department of Oncology, Goeteborg (Sweden); Waengberg, Bo [Sahlgrenska University Hospital, Department of Surgery, Goeteborg (Sweden); Larsson, Maria [University of Gothenburg, Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy, Goeteborg (Sweden); Forssell-Aronsson, Eva; Bernhardt, Peter [University of Gothenburg, Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy, Goeteborg (Sweden); Sahlgrenska University Hospital, Department of Medical Physics and Medical Bioengineering, Goeteborg (Sweden)

    2015-05-01

    Peptide receptor radionuclide therapy (PRRT) has become an important treatment option in the management of advanced neuroendocrine tumours. Long-lasting responses are reported for a majority of treated patients, with good tolerability and a favourable impact on quality of life. The treatment is usually limited by the cumulative absorbed dose to the kidneys, where the radiopharmaceutical is reabsorbed and retained, or by evident haematological toxicity. The aim of this study was to evaluate how renal function affects (1) absorbed dose to the kidneys, and (2) the development of haematological toxicity during PRRT treatment. The study included 51 patients with an advanced neuroendocrine tumour who received {sup 177}Lu-DOTATATE treatment during 2006 - 2011 at Sahlgrenska University Hospital in Gothenburg. An average activity of 7.5 GBq (3.5 - 8.2 GBq) was given at intervals of 6 - 8 weeks on one to five occasions. Patient baseline characteristics according to renal and bone marrow function, tumour burden and medical history including prior treatment were recorded. Renal and bone marrow function were then monitored during treatment. Renal dosimetry was performed according to the conjugate view method, and the residence time for the radiopharmaceutical in the whole body was calculated. A significant correlation between inferior renal function before treatment and higher received renal absorbed dose per administered activity was found (p < 0.01). Patients with inferior renal function also experienced a higher grade of haematological toxicity during treatment (p = 0.01). The residence time of {sup 177}Lu in the whole body (range 0.89 - 3.0 days) was correlated with grade of haematological toxicity (p = 0.04) but not with renal absorbed dose (p = 0.53). Patients with inferior renal function were exposed to higher renal absorbed dose per administered activity and developed a higher grade of haematological toxicity during {sup 177}Lu-DOTATATE treatment. The study confirms the

  10. Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828) on the coast of Ceara, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de S., E-mail: wspereira@inb.gov.br [Industrias Nucleares do Brasil (INB), Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerios. Coordenacao de Protecao Radiologica de Caldas; Kelecom, Alphonsem [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Lab. de Radiobiologia e Radiometria; Py Junior, Delcy de A. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Geociencias. Programa de Pos-Graduacao em Ciencia Ambiental

    2010-07-01

    A methodology was developed for converting the activity concentration of radionuclides (Bq kg{sup -1}) into absorbed dose rate (Gy y{sup -1}), aiming an approach to environmental radioprotection based on the concept of standard dose limit. The model considers only the internal absorbed dose rate. This methodology was applied to the cubera snapper fish (Lutjanus cyanopterus, Cuvier, 1828) caught off the coast of Ceara. The natural radionuclides considered were uranium-238, radium-226, lead-210, thorium-232 and radium-228. The absorbed dose rates were calculated for individual radionuclides and the type of emitted radiation. The average dose rate due to these radionuclides was 5.36 {mu}Gy y{sup -1}, a value six orders of magnitude smaller than the threshold value of absorbed dose rate used in this study (3.65 10{sup 3} mGy y{sup -1}), and similar to that found in the literature for benthic fish. Ra-226 and U- 238 contributed 67% and 22% of the absorbed dose rate, followed by Th-232 with 10%. Ra-228 and Pb-210, in turn, accounted for less than 1% of the absorbed dose rate. This distribution is somewhat different from that reported in the literature, where the Ra-226 accounts for 86% of the absorbed dose rate. (author)

  11. Analyse of the international recommendations on the calculation of absorbed dose in the biota; Analise das recomendacoes internacionais sobre calculo de dose absorvida na biota

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de S.; Py Junior, Delcy de A., E-mail: wspereira@inb.gov.b, E-mail: delcy@inb.gov.b [Industrias Nucleares do Brasil (UTM/INB), Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerios; Universidade Federal Fluminense (LARARA/UFF), Niteroi, RJ (Brazil). Lab. de Radiobiologia e Radiometria; Kelecom, Alphonse [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Ciencia Ambiental

    2011-10-26

    This paper evaluates the recommendations of ICRP which has as objective the environmental radioprotection. It was analysed the recommendations 26, 60, 91, 103 and 108 of the ICRP. The ICRP-103 defined the concept of animal and plant of reference (APR) to be used in the RAP based on the calculation of absorbed dose based on APR concept. This last view allows to build a legal framework of environmental protection with a etic, moral and scientific visualization, more defensible than the anthropomorphic concept

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

    Energy Technology Data Exchange (ETDEWEB)

    Elschot, Mattijs; Nijsen, Johannes F.W.; Lam, Marnix G.E.H.; Smits, Maarten L.J.; Prince, Jip F.; Bosch, Maurice A.A.J. van den; Zonnenberg, Bernard A.; Jong, Hugo W.A.M. de [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine, Utrecht (Netherlands); Viergever, Max A. [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine, Utrecht (Netherlands); University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands)

    2014-10-15

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

  13. Supplementary comparison CCRI(I)-S2 of standards for absorbed dose to water in 60Co gamma radiation at radiation processing dose levels

    DEFF Research Database (Denmark)

    Burns, D. T.; Allisy-Roberts, P. J.; Desrosiers, M. F.

    2011-01-01

    rate effect is presented and discussed briefly. 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......Eight national standards for absorbed dose to water in 60Co gamma radiation at the dose levels used in radiation processing have been compared over the range from 1 kGy to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer dosimeters. The comparison was organized...

  14. Supplementary comparison CCRI(I)-S2 of standards for absorbed dose to water in {sup 60}Co gamma radiation at radiation processing dose levels

    Energy Technology Data Exchange (ETDEWEB)

    Burns, D.T.; Allisy-Roberts, P.J. [Bureau International des Poids et Mesures, Pavillon de Breteuil, F-92312 Sevres cedex (France); Desrosiers, M.F. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Sharpe, P.H.G. [National Physical Laboratory, Teddington, Middlesex (United Kingdom); Pimpinella, M. [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, Rome (Italy); Lourenco, V. [CEA Saclay, LIST, Laboratoire National Henri Becquerel, Gif-sur-Yvette (France); Zhang, Y.L. [National Institute of Metrology, Beijing (China); Miller, A. [Riso High Dose reference Laboratory, Riso DTU, Roskilde (Denmark); Generalova, V. [Institute for Physical-Technical and Radiotechnical Measurements, Moscow (Russian Federation); Sochor, V. [Czech Metrology Institute, Brno (Czech Republic)

    2011-06-15

    Eight national standards for absorbed dose to water in {sup 60}Co gamma radiation at the dose levels used in radiation processing have been compared over the range from 1 kGy to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer dosimeters. The comparison was organized by the Bureau International des Poids et Mesures, who also participated at the lowest dose level using their radiotherapy-level standard for the same quantity. The national standards are in general agreement within the standard uncertainties, which are in the range from 1 to 2 parts in 10{sup 2}. Evidence of a dose rate effect is presented and discussed briefly. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

    Alsadius, David, E-mail: david.alsadius@oncology.gu.se [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg (Sweden); Hedelin, Maria [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, Karolinska Institute, Stockholm (Sweden); Lundstedt, Dan [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg (Sweden); Pettersson, Niclas [Department of Radiophysics, Sahlgrenska Academy at University of Gothenburg (Sweden); Wilderaeng, Ulrica [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg (Sweden); Steineck, Gunnar [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, Karolinska Institute, Stockholm (Sweden)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-02-07

    Metastatic and recurrent differentiated thyroid carcinoma is preferably treated with (131)I, 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 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, M., E-mail: marta.bueno@upc.edu; Duch, M. A. [Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain); Carrasco, P.; Jornet, N. [Servei de Radiofísica i Radioprotecció, Hospital de la Santa Creu i de Sant Pau, 08025 Barcelona (Spain); Muñoz-Montplet, C. [Servei de Física Mèdica i Protecció Radiològica, Institut Català d’Oncologia—Girona, 17007 Girona (Spain)

    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.

  19. Absorbed dose due to radioiodine therapy by organs of patients with hyperthyroidism; Dose absorvida em orgaos de pacientes com hipertiroidismo devido a radioiodoterapia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, F.F.; Khoury, H.J.; Bertelli Neto, L. [Pernambuco Univ., Recife, PE (Brazil); Laboratorios CERPE, Recife, PE (Brazil); Bertelli Neto, L. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)

    1999-07-01

    The dose absorbed by organs of patients with hyperthyroidism treated with {sup 131} I was estimated by using the MIRDOSE computer program and data from ICRP-53. The calculation were performed using effective half-life and uptake average values, which were determined for 17 patients treated with 370 MBq and 555MBq of {sup 131} I. The results shown that the dose in the thyroid, for a 370 MBq administrated activity, was of 99 Gy and 49.5 Gy for 60 g and 80 g thyroid respectively. The average dose estimated in other organs were relatively low, presenting values lower than 0.1 Gy in the kidneys, bone marrow and ovaries and 0.19 Gy in the stomach.

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

    Institute of Scientific and Technical Information of China (English)

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

    2012-01-01

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Goes, E.G., E-mail: eggoes@terra.com.b [Regional Blood Center of Ribeirao Preto, Ribeirao Preto, SP (Brazil); Nicolucci, P.; Nali, I.C. [Physics and Mathematics Department, University of Sao Paulo, Ribeirao Preto, SP (Brazil); Pela, C.A.; Bruco, J.L. [Physics and Mathematics Department, University of Sao Paulo, Ribeirao Preto, SP (Brazil); Center of Instrumentation, Dosimetry and Radioprotection, University of Sao Paulo, Ribeirao Preto, SP (Brazil); Borges, J.C. [Center of Instrumentation, Dosimetry and Radioprotection, University of Sao Paulo, Ribeirao Preto, SP (Brazil); Covas, D.T. [Regional Blood Center of Ribeirao Preto, Ribeirao Preto, SP (Brazil); Center for Cell-Based Therapy, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP (Brazil)

    2010-06-15

    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.

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

    Science.gov (United States)

    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.

  4. Absorbed dose at subcellular level by Monte Carlo simulation for a {sup 99m}Tc-peptide with nuclear internalization

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E. L.; Ferro F, G. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Santos C, C. L., E-mail: leticia.rojas@inin.gob.m [Universidad Autonoma del Estado de Mexico, Paseo Tollocan esquina Paseo Colon s/n, Toluca 50120, Estado de Mexico (Mexico)

    2010-10-15

    The utility of radiolabeled peptides for the early and specific diagnosis of cancer is being investigated around the world. Recent investigations have demonstrated the specificity of {sup 99m}Tc-bombesin conjugates to target breast and prostate cancer cells. The novel idea of adding the Tat (49-57) peptide to the radiopharmaceutical in order to penetrate the cell nucleus is a new proposal for therapy at cellular level. {sup 99m}Tc radionuclide produces Auger energy of 0.9 keV/decay and internal conversion electron energy of 15.4 keV/decay, which represent 11.4% of the total {sup 99m}Tc energy released per decay. It is expected that the dose delivered at specific microscopic levels in cancer cells induce a therapeutic effect. The aim of this research was to assess in vitro internalization kinetics in breast and prostate cancer cells of {sup 99m}Tc-Tat(49-57)-bombesin and to evaluate the radiation absorbed dose at subcellular level simulating the electron transport. The pen main program from the 2006 version of the Penelope code was used to simulate and calculate the absorbed dose by Auger and internal conversion electron contribution in the membrane, cytoplasm and nucleus of Pc-3 prostate cancer and MCF7 and MDA human breast cancer cell lines. Nuclear data were obtained from the 2002 BNM-LNHB {sup 99m}Tc decay scheme. The spatial distribution of the absorbed doses to the membrane, cytoplasm and nucleus were calculated using a geometric model built from real images of cancer cells. The elemental cell composition was taken from the literature. The biokinetic data were obtained evaluating total disintegrations in each subcellular compartment by integration of the time-activity curves acquired from experimental data. Results showed that 61, 63 and 46% of total disintegrations per cell-bound {sup 99m}Tc-Tat-Bn activity unit occurred in the nucleus of Pc-3, MCF7 and MDA-MB231 respectively. {sup 99m}Tc--Tat-Bn absorbed doses were 1.78, 5.76 and 2.59 Gy/Bq in the nucleus of

  5. COMPARISON BETWEEN ABSORBED DOSES IN TARGET ORGANS IN PANORAMIC RADIOGRAPHY, USING SINGLE EMULSION AND DOUBLE EMULSION FILMS

    Directory of Open Access Journals (Sweden)

    A. R. Talaeipour

    2007-07-01

    Full Text Available "nThe use of panoramic radiography, due to its numerous advantages, is increasing. Radiographic films used in this technique are of double emulsion (DE type which are used with intensifying screens. Single emulsion (SE films can also be used. The purpose of this study was to determine the exposure parameters to achieve an appropriate optical density in these two types of films, and to estimate under such parameters, radiation doses to mandibular bone marrow (MBM, thyroid gland and parotid gland. This study was performed through a tissue equivalent phantom. First, with various tube voltage and tube current, 128 radiographs were taken of phantom with these two types of films. After examining the optical densities, the exposure parameters under which both films have the same density, were determined. Then, phantom again was exposed and MBM, thyroid gland and parotid gland absorbed doses were measured, using TLDs. It was demonstrated that: 1 SE films, in order to provide appropriate optical density, require two times radiation in comparison with double emulsion film; 2 using SE films increases MBM dose, up to 2-2.5 times, thyroid gland dose up to 1.7-2 times and parotid gland dose up to 1.3 times, in comparison with DE films; 3 in DE films, under lower exposure parameters and desirable processing, MBM dose up to 3.5 times, thyroid gland dose up to 1.5 times and parotid gland dose up to 2.5 times will increase. Considering that the risk of radiation induced cancers increases with repeated radiation doses, using SE films is not recommended.

  6. Co-trial on ESR identification and estimates of. gamma. -ray and electron absorbed doses given to meat and bones

    Energy Technology Data Exchange (ETDEWEB)

    Desrosiers, M.F.; McLaughlin, W.L.; Sheahen, L.A. (National Inst. of Standards and Technology (NCTL), Gaithersburg, MD (United States)); Dodd, N.J.F.; Lea, J.S. (Paterson Inst. for Cancer Research, Manchester (UK)); Evans, J.C.; Rowlands, C.C. (School of Chemistry and Applied Chemistry, Cardiff (UK)); Raffi, J.J.; Agnel, J.-P.L. (Laboratoire de Radiochemie des Constituants des Aliments, Cadarache (France))

    1990-01-01

    A multinational co-trial was organized to determine if electron spin resonance (ESR) spectroscopy could be used to monitor foods exposed to ionizing radiation. The bones of chicken legs, frog legs and pork rib bones were prepared and distributed as unknowns to the participating laboratories. In every instance, non-irradiated bones were correctly identified as such. Moreover, irradiated bones were not only correctly identified, but relatively good estimates of the absorbed dose were obtained. An intercomparison of the different approaches used by each laboratory is discussed, and recommendations for future trials are presented. (author).

  7. Methodology for calibration of ionization chambers for X-ray of low energy in absorbed dose to water

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, C.T.; Vivolo, V.; Potiens, M.P.A., E-mail: camila_fmedica@hotmail.com [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The beams of low energy X-ray (10 to 150 kV) are used in several places in the world to treat a wide variety of surface disorders, and between these malignancies. As in Brazil, at this moment, there is no calibration laboratory providing the control service or calibration of parallel plate ionization chambers, the aim of this project was to establish a methodology for calibration of this kind of ionization chambers at low energy X-ray beams in terms of absorbed dose to water using simulators in the LCI. (author)

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

    Science.gov (United States)

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

    2016-06-21

    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 (192)Ir 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 (131)I and (90)Y radionuclides. We investigated convergence of GBBS by analyzing different meshes ([Formula: see text]), energy group structures ([Formula: see text]) for each radionuclide component, angular quadrature orders ([Formula: see text], and scattering order expansions ([Formula: see text]-[Formula: see text]); 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 (90)Y and (131)I were  -6%. The GBBS ATTILA was benchmarked against MC in the nuclear medicine regime. GBBS can be a

  9. The role of nuclear reactions in Monte Carlo calculations of absorbed and biological effective dose distributions in hadron therapy

    CERN Document Server

    Brons, S; Elsässer, T; Ferrari, A; Gadioli, E; Mairani, A; Parodi, K; Sala, P; Scholz, M; Sommerer, F

    2010-01-01

    Monte Carlo codes are rapidly spreading among hadron therapy community due to their sophisticated nuclear/electromagnetic models which allow an improved description of the complex mixed radiation field produced by nuclear reactions in therapeutic irradiation. In this contribution results obtained with the Monte Carlo code FLUKA are presented focusing on the production of secondary fragments in carbon ion interaction with water and on CT-based calculations of absorbed and biological effective dose for typical clinical situations. The results of the simulations are compared with the available experimental data and with the predictions of the GSI analytical treatment planning code TRiP.

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

    Science.gov (United States)

    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

  11. Absorbed dose distribution of brachytherapy sources through Fricke xylenol gel dosimetry; Distribuicao da dose absorvida de fontes braquiterapicas atraves da dosimetria bidimensional Fricke xylenol gel

    Energy Technology Data Exchange (ETDEWEB)

    Mangueira, T.F.; Almeida, A. de [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Departamento de Fisica e Matematica; Costa, J.J.L., E-mail: lucas@ifg.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFG), Inhumas, GO (Brazil); Caldas, Linda V.E.; Oliveira, L.N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Moreira, M.V. [Instituto Ribeiraopretano de Combate ao Cancer (IRPCC), Ribeirao Preto, SP (Brazil)

    2013-07-15

    brachytherapy techniques used throughout the world is derived, or has as a principle the method Paterson-Parker (PP), which ensures the homogeneity of 10% of the treatment plan (target volume), the distance 'h' from the plane formed the source distribution brachytherapy irradiation. Thus, the method ensures that the maximum dose does not exceed 10% of the dose set to satisfy the criteria for uniformity. In this study, we evaluated the method PP measures in dose distribution, having as the Fricke Xylenol Gel dosimeter (FXG), which was irradiated with an orderly distribution of sources of treatment. The distribution was made with eight sources of {sup 137}Cs, distributed in the rules of the PP method, with h = 5.75 mm. The phantom was a distribution of 5 x 5 cm{sup 2} standard spectrophotometer cuvettes (each 1.25 x 1.25 x 3.5 cm{sup 3} optical path length) FXG filled with a total volume of 5 x 5 x 3.5 cm{sup 3}. The phantom was irradiated in a time of 3.3 h resulting in an absorbed dose of 10 Gy in the treatment plan. Then, the FXG was read in a monospectrophotometer and their results were processed in a routine MATLAB Registered-Sign thereby obtaining the dose distribution. The homogeneity was calculated at 7.8% in the treatment plan, which is in accordance with the protocols of IAEA-TECDOC-602. (author)

  12. ON THE RELATIONSHIP BETWEEN AMBIENT DOSE EQUIVALENT AND ABSORBED DOSE IN AIR IN THE CASE OF LARGE-SCALE CONTAMINATION OF THE ENVIRONMENT BY RADIOACTIVE CESIUM

    Directory of Open Access Journals (Sweden)

    V. P. Ramzaev

    2015-01-01

    Full Text Available One of the main aims of the study was an experimental determination of the conversion coefficient from ambient dose equivalent rate, Н*(10, to absorbed dose rate in air, D, in the case of radioactive contamination of the environment following the Chernobyl accident. More than 800 measurements of gamma-dose rates in air were performed at the typical locations (one-storey residential house, street, yard, kitchen-garden, ploughed field, undisturbed grassland, forest of rural settlements and their surroundings in the heavily contaminated areas of the Bryansk region, Russia in the period of 1996–2010. Five commercially available models of portable gamma-ray dosimeters were employed in the investigation. All tested dosimeters were included into the State register of approved measuring instruments of Russia. In all dosimeters, scintillation detectors are used as detection elements. A photon spectrometry technique is applied in the dosimeters to determine gamma dose rate in air. The dosimeters are calibrated in terms of exposure rate, X, absorbed dose rate in air, D, and ambient dose equivalent rate, Н*(10. A very good agreement was found between different dosimeters calibrated in the same units; the reading ratios were close to 1 and the correlation coefficients (Pearson’s or Spearman’s were higher than 0.99. The Н*(10/D ratio values were location-specific ranging from 1.23 Sv/Gy for undisturbed grasslands and forests to 1.47 Sv/Gy for wooden houses and asphalted streets. A statistically significant negative correlation (Spearman’s coefficient = -0.833; P<0.01; n=9 was found between the Н*(10/D ratio and the average energy of gamma-rays determined with a NaI(Tl-based gamma-ray monitor. For the whole area of a settlement and its surroundings, the average ratio of Н*(10 to D was calculated as 1.33 Sv/Gy. The overall conversion coefficient from ambient dose equivalent rate, Н*(10, to external effective dose rate, Ė, for adults was estimated

  13. Standard Practice for Application of Thermoluminescence-Dosimetry (TLD) Systems for Determining Absorbed Dose in Radiation-Hardness Testing of Electronic Devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for the use of thermoluminescence dosimeters (TLDs) to determine the absorbed dose in a material irradiated by ionizing radiation. Although some elements of the procedures have broader application, the specific area of concern is radiation-hardness testing of electronic devices. This practice is applicable to the measurement of absorbed dose in materials irradiated by gamma rays, X rays, and electrons of energies from 12 to 60 MeV. Specific energy limits are covered in appropriate sections describing specific applications of the procedures. The range of absorbed dose covered is approximately from 10−2 to 104 Gy (1 to 106 rad), and the range of absorbed dose rates is approximately from 10−2 to 1010 Gy/s (1 to 1012 rad/s). Absorbed dose and absorbed dose-rate measurements in materials subjected to neutron irradiation are not covered in this practice. Further, the portion of these procedures that deal with electron irradiation are primarily intended for use in parts testin...

  14. Absorbed dose measurements in mammography using Monte Carlo method and ZrO{sub 2}+PTFE dosemeters

    Energy Technology Data Exchange (ETDEWEB)

    Duran M, H. A.; Hernandez O, M. [Departamento de Investigacion en Polimeros y Materiales, Universidad de Sonora, Blvd. Luis Encinas y Rosales s/n, Col. Centro, 83190 Hermosillo, Sonora (Mexico); Salas L, M. A.; Hernandez D, V. M.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Pinedo S, A.; Ventura M, J.; Chacon, F. [Hospital General de Zona No. 1, IMSS, Interior Alameda 45, 98000 Zacatecas (Mexico); Rivera M, T. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, IPN, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F.(Mexico)], e-mail: hduran20_1@hotmail.com

    2009-10-15

    Mammography test is a central tool for breast cancer diagnostic. In addition, programs are conducted periodically to detect the asymptomatic women in certain age groups; these programs have shown a reduction on breast cancer mortality. Early detection of breast cancer is achieved through a mammography, which contrasts the glandular and adipose tissue with a probable calcification. The parameters used for mammography are based on the thickness and density of the breast, their values depend on the voltage, current, focal spot and anode-filter combination. To achieve an image clear and a minimum dose must be chosen appropriate irradiation conditions. Risk associated with mammography should not be ignored. This study was performed in the General Hospital No. 1 IMSS in Zacatecas. Was used a glucose phantom and measured air Kerma at the entrance of the breast that was calculated using Monte Carlo methods and ZrO{sub 2}+PTFE thermoluminescent dosemeters, this calculation was completed with calculating the absorbed dose. (author)

  15. Standardisation and Validation of Cytogenetic Markers to Quantify Radiation Absorbed Dose

    Directory of Open Access Journals (Sweden)

    Venkatachalam Perumal

    2011-02-01

    Full Text Available The amounts of radiation exposure received by radiation workers are monitored generally by physical dosimeters like thermoluminescence dosimeter (TLD and film badge. However, in practice the over-exposure recorded by physical dosimeters need to be confirmed with biological dosimeters. In addition to confirming the dose recorded by physical dosimeters, biological dosimeters play an important role in estimating the doses received during accidental exposures. Exposure to high levels of radiation induces certain  biochemical, biophysical, and immunological changes (biomarkers in a cell. Measurement of these changes are generally precise but cannot be effectively used to assess the dose, as the level of these changes return to normalcy within hours to months after exposure. Thus, among various biological indicators, cytogenetic indicators are considered practical and reliable for dose estimation. The paper highlights the importance and establishment of biodosimetry facility using genetic markers such as the sensitive dicentric chromosomes, rapid micronucleus assay and stable translocations measured using fluorescence in situ hybridisation and GTG banding for retrospective dose estimation. Finally, the development of gH2AX assay, as a potential marker of triage dosimeter, is discussed.Defence Science Journal, 2011, 61(2, pp.125-132, DOI:http://dx.doi.org/10.14429/dsj.61.832

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

    Science.gov (United States)

    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.

  17. Development of methodology for assessment of absorbed dose and stopping power for low energy conversion electrons; Desenvolvimento de uma metodologia para estimativa da dose absorvida e do poder de freamento para eletrons de conversao de baixa energia

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Ivan Pedro Salati de

    1995-08-01

    The evaluation of absorbed dose in the case of external and internalcontamination due to radionuclides is sometimes hard, because of the difficulties in the assessment of the absorbed dose caused by electrons with energy less than 100 KeV in mucous membrane. In this work, a methodology for assessment of absorbed dose and stopping power in VYNS (co-polymer of polivinyl chloride - acetate) absorbers, for the 62.5 KeV and 84-88 KeV energy {sup 109} Cd conversion electrons, working with a 4 {pi} proportional pressurized detector, is presented. In order to assure the reproducibility of measurement conditions, one of the detector halves has been used to obtain a spectrum of a thin {sup 109} Cd source, without absorber. The other half of the detector was used in concomitance to obtain spectra with different thicknesses if absorber. The absorbed energy was obtained subtracting each spectrum with absorber from the spectrum without absorber, which were stored in a microcomputer connected to signal processing systems by ACE type interface. The VYNS weight and thickness were evaluated using common radionuclide metrology procedures. As VYNS has characteristics similar to a tissue equivalent material, the results obtained are consistent with dosimetric concepts and have a good agreement with those of the literature. (author)

  18. Detector photon response and absorbed dose and their applications to rapid triage techniques

    Science.gov (United States)

    Voss, Shannon Prentice

    As radiation specialists, one of our primary objectives in the Navy is protecting people and the environment from the effects of ionizing and non-ionizing radiation. Focusing on radiological dispersal devices (RDD) will provide increased personnel protection as well as optimize emergency response assets for the general public. An attack involving an RDD has been of particular concern because it is intended to spread contamination over a wide area and cause massive panic within the general population. A rapid method of triage will be necessary to segregate the unexposed and slightly exposed from those needing immediate medical treatment. Because of the aerosol dispersal of the radioactive material, inhalation of the radioactive material may be the primary exposure route. The primary radionuclides likely to be used in a RDD attack are Co-60, Cs-137, Ir-192, Sr-90 and Am-241. Through the use of a MAX phantom along with a few Simulink MATLAB programs, a good anthropomorphic phantom was created for use in MCNPX simulations that would provide organ doses from internally deposited radionuclides. Ludlum model 44-9 and 44-2 detectors were used to verify the simulated dose from the MCNPX code. Based on the results, acute dose rate limits were developed for emergency response personnel that would assist in patient triage.

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

    Science.gov (United States)

    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

  20. Optimization of Parameters in 16-slice CT-‌‌scan Protocols for Reduction of the Absorbed Dose

    Directory of Open Access Journals (Sweden)

    Shahrokh Naseri

    2014-08-01

    Full Text Available Introduction In computed tomography (CT technology, an optimal radiation dose can be achieved via changing radiation parameters such as mA, pitch factor, rotation time and tube voltage (kVp for diagnostic images. Materials and Methods In this study, the brain, abdomen, and thorax scaning was performed using Toshiba 16-slice scannerand standard AAPM and CTDI phantoms. AAPM phantom was used for the measurement of image-related parameters and CTDI phantom was utilized for the calculation of absorbed dose to patients. Imaging parameters including mA (50-400 mA, pitch factor (1 and 1.5 and rotation time (range of 0.5, 0.75, 1, 1.5 and 2 seconds were considered as independent variables. The brain, abdomen and chest imaging was performed multi-slice and spiral modes. Changes in image quality parameters including contrast resolution (CR and spatial resolution (SR in each condition were measured and determined by MATLAB software. Results After normalizing data by plotting the full width at half maximum (FWHM of point spread function (PSF in each condition, it was observed that image quality was not noticeably affected by each cases. Therefore, in brain scan, the lowest patient dose was in 150 mA and rotation time of 1.5 seconds. Based on results of scanning of the abdomen and chest, the lowest patient dose was obtained by 100 mA and pitch factors of 1 and 1.5. Conclusion It was found that images with acceptable quality and reliable detection ability could be obtained using smaller doses of radiation, compared to protocols commonly used by operators.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  3. Modeling the absorbed dose to the common carotid arteries following radioiodine treatment of benign thyroid disease

    DEFF Research Database (Denmark)

    la Cour, Jeppe Lerche; Hedemann-Jensen, Per; Søgaard-Hansen, Jens

    2013-01-01

    External fractionated radiotherapy of cancer increases the risk of cardio- and cerebrovascular events, but less attention has been paid to the potential side effects on the arteries following internal radiotherapy with radioactive iodine (RAI), i.e. 131-iodine. About 279 per million citizens...... in the western countries are treated each year with RAI for benign thyroid disorders (about 140,000 a year in the EU), stressing that it is of clinical importance to be aware of even rare radiation-induced side effects. In order to induce or accelerate atherosclerosis, the dose to the carotid arteries has...

  4. CALCULATION STUDIES OF SPATIAL DISTRIBUTION OF THE ABSORBED DOSE RATE FOR VARIOUS SEEDS

    Directory of Open Access Journals (Sweden)

    N. A. Nerozin

    2015-01-01

    Full Text Available Purpose. Conducting computational studies of dosimetric characteristics of microsources with the radionuclide I‑125, pilot production of which is established in the research and production complex of isotope and radiopharmaceuticals, JSC “State Scientific Centre of the Russian Federation — Institute for Physics and Power Engineering named after A. I. Leypunsky” (SSC RF IPPE. Sources of production IPPE are similar to the model 6711 of the company Nicomed Amersham, dosimetric characteristics of which are standardized in accordance with the TG43 AAPM formalism.Materials and methods. Microsourse «SEED No. 6711» (model of the company Nicomed Amersham is hermetically sealed in a titanium capsule silver rod covered with a thin layer of radioactive I‑125. The half-life of iodine‑125 is 59,43 days. In the process of decay of I‑125 is converted into the Te‑125.Calculation of parameters of microsources and their comparison with the standard model 6711 is carried out with use of the computer code MCNP.Results. The method of calculation of the basic dosimetric characteristics of the microsourse SSC RF-IPPE in accordance with the TG43 formalism is developed. A comparative analysis of experimental data and calculated results by MCNP code, which allowed to identify possible reasons for differences, is performed. The estimated dose characteristics and recommended standard data for dose characteristics of micro «SEED No. 6711» are compared.Conclusions. There are two possible reasons for the differences between experimental and calculated results. The first one may be the roughness of the surface of a silver rod or diffusion of radioactive iodine in silver. The second reason might be the difference of the cross sections of the characteristic radiation of silver used in MCNP code. In the comparison of calculated dose characteristics and recommended standard the role of the application activity is very important. In compliance with the standard

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

    Science.gov (United States)

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

    2016-02-01

    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.

  6. Estimation of organ-absorbed radiation doses during 64-detector CT coronary angiography using different acquisition techniques and heart rates: a phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, Kosuke; Koshida, Kichiro; Kawashima, Hiroko (Dept. of Quantum Medical Technology, Faculty of Health Sciences, Kanazawa Univ., Kanazawa (Japan)), email: matsuk@mhs.mp.kanazawa-u.ac.jp; Noto, Kimiya; Takata, Tadanori; Yamamoto, Tomoyuki (Dept. of Radiological Technology, Kanazawa Univ. Hospital, Kanazawa (Japan)); Shimono, Tetsunori (Dept. of Radiology, Hoshigaoka Koseinenkin Hospital, Hirakata (Japan)); Matsui, Osamu (Dept. of Radiology, Faculty of Medicine, Kanazawa Univ., Kanazawa (Japan))

    2011-07-15

    Background: Though appropriate image acquisition parameters allow an effective dose below 1 mSv for CT coronary angiography (CTCA) performed with the latest dual-source CT scanners, a single-source 64-detector CT procedure results in a significant radiation dose due to its technical limitations. Therefore, estimating the radiation doses absorbed by an organ during 64-detector CTCA is important. Purpose: To estimate the radiation doses absorbed by organs located in the chest region during 64-detector CTCA using different acquisition techniques and heart rates. Material and Methods: Absorbed doses for breast, heart, lung, red bone marrow, thymus, and skin were evaluated using an anthropomorphic phantom and radiophotoluminescence glass dosimeters (RPLDs). Electrocardiogram (ECG)-gated helical and ECG-triggered non-helical acquisitions were performed by applying a simulated heart rate of 60 beats per minute (bpm) and ECG-gated helical acquisitions using ECG modulation (ECGM) of the tube current were performed by applying simulated heart rates of 40, 60, and 90 bpm after placing RPLDs on the anatomic location of each organ. The absorbed dose for each organ was calculated by multiplying the calibrated mean dose values of RPLDs with the mass energy coefficient ratio. Results: For all acquisitions, the highest absorbed dose was observed for the heart. When the helical and non-helical acquisitions were performed by applying a simulated heart rate of 60 bpm, the absorbed doses for heart were 215.5, 202.2, and 66.8 mGy for helical, helical with ECGM, and non-helical acquisitions, respectively. When the helical acquisitions using ECGM were performed by applying simulated heart rates of 40, 60, and 90 bpm, the absorbed doses for heart were 178.6, 139.1, and 159.3 mGy, respectively. Conclusion: ECG-triggered non-helical acquisition is recommended to reduce the radiation dose. Also, controlling the patients' heart rate appropriately during ECG-gated helical acquisition with

  7. The analysis of impact of irregularity in radionuclide coating of scaffold on the distribution of absorbed dose produced by grid of microsources

    Directory of Open Access Journals (Sweden)

    N. A. Nerosin

    2015-01-01

    Full Text Available The impact of irregularity in radionuclide coating of scaffold on the distribution of absorbed dose produced by grid of microsources was analyzed. On engineering software MATHCAD the program for calculation of absorbed dose produced by grid of microsources was created. To verify this algorithm the calculation model for MCNP code was established and represented the area consisted of soft biological tissue or any other tissue in which the grid of microsources was incorporated. Using the developed system the value of possible systematic irregular coating of radioactivity on the microsource’s core was analyzed. The distribution of activity along the surface of microsource was simulated to create distribution of absorbed dose rate corresponding to experimental data on radiation injury. The obtained model of microsource with irregular distribution of activity was compared to conventional microsource with core coated regularly along the entire area of the silver stem by main dosimetry characteristics. The results showed that even for extremely irregular distribution of activity the distribution of dose rate produced by microsource in the tumor area was not substantially different from dose-rate field obtained for microsource with regularly coated activity. The differences in dose rates (up to 10% in areas which were the nearest to the center of the grid were significantly lower than its decline from center to periphery of the grid. For spatial distribution of absorbed dose for specific configuration of microsource set and tracing of curves of equal level by selected cut-off the program SEEDPLAN was developed. The developed program represents precisely enough the spatial distribution of selected configuration set of microsources using results of calculation data for absorbed dose around the single microsource as basic data and may be used for optimal planning of brachytherapy with microsources. 

  8. Effect of absorbed dose and storage length on electron paramagnetic resonance (EPR) signal strength in irradiated alfalfa seeds

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A kind of alfalfa seeds was irradiated by 1, 2, 3, 4 and 5 kGy at a dose rate of 6.288 kGy. h-1 in a self-shielded irradiator of 137Cs gamma rays. The EPR spectra, which were measured subsequently between 0.3401and 0.3501 T, showed that there was a direct proportional relationship between the EPR signal strength of free radicals produced by gamma irradiation in the alfalfa seeds and absorbed dose. The first derivative EPR spectra of the alfalfa seeds were very clear and easy to identify. However, the EPR signal strength of the peak-to-peak amplitude decreased rapidly and most of them decayed beyond 50% within 3 days after the seeds were irradiated. It tended to stabilize after half a month since the seeds were irradiated. The differences of the EPR signal strength between the irradiated and unirradiated alfalfa seeds still remained. All seeds were stored at ambient temperature for more than 3months. Therefore, using EPR spectrometry technique to measure free radicals in alfalfa seeds as a means to determine whether the seeds have been irradiated or not is feasible, relatively fast and simple.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A' aisah [Malaysian Nuclear Agency (Nuclear Malaysia), Bangi 43000 Kajang Selangor (Malaysia); Ahmad, Pauzi [Universiti Kebangsaan Malaysia, 43600 UKM, Bangi Selangor (Malaysia)

    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.

  10. Absorbed dose calculation from beta and gamma rays of 131I in ellipsoidal thyroid and other organs of neck with MCNPX code

    Directory of Open Access Journals (Sweden)

    Mohammad Mirzaie

    2012-09-01

    Full Text Available Background: The 131I radioisotope is used for diagnosis and treatment of hyperthyroidism and thyroid cancer. In optimized Iodine therapy, a specific dose must be reached to the thyroid gland with minimum radiation to the cervical spine, cervical vertebrae, neck tissue, subcutaneous fat and skin. Dose measurement inside the alive organ is difficult therefore the aim of this research was dose calculation in the organs by MCNPX code. Materials and Methods: First of all, the input file for MCNPX code has been prepared to calculate F6 and F8 tallies for ellipsoidal thyroid lobes with long axes is tow times of short axes which the 131I is distributed uniformly inside the lobes. Then the code has been run for F6 and F8 tallies for variation of lobe volume from 1 to 25 milliliters. From the output file of tally F6, the gamma absorbed dose in ellipsoidal thyroid, spinal neck, neck bone, neck tissue, subcutaneous fat layer and skin for the volume lobe variation from 1 ml to 25 ml have been derived and the graphs are drew. As well as, form the output of F8 tally the absorbed energy of beta in thyroid and soft tissue of neck is obtained and listed in the table and then absorbed dose of bate has been calculated. Results: The results of this research show that for constant activity in thyroid, the absorbed dose of gamma decreases about 88.3% in thyroid, 6.9% at soft tissue, 19.3% in adipose layer and 17.4% in skin, but it increases 32.1% in spinal of neck and 32.3% in neck bone when the lobe volume varied from 1 to 25 milliliters. For the same situation, the beta absorbed dose decreases 95.9% in thyroid and 64.2% in soft tissue. Conclusion: For the constant activity in thyroid by increasing the thyroid volume, absorbed dose of gamma in thyroid and soft tissue of neck, adipose layer under the skin and skin of neck decreased, but it increased at spinal of neck and neck bone. Also, by increasing of the lobe volume in constant activity, the beta absorbed dose

  11. Comparison beta absorbed dose from 203Hg, 166Ho and 177LU isotopes in cortex and medulla in tree part kidney and integrated kidney using Monte Carlo method

    Directory of Open Access Journals (Sweden)

    Mohammad Mirzaei

    2015-04-01

    Full Text Available Background: Large quantities of radiopharmaceuticals prescribed for treatment and diagnosis are excreted through kidney. Therefore, radiation unwanted dose is created in kidney. As a result, exact calculation of prescribed medicine amount is important. In Mird pamphlet, 5 kidneys have considered in ellipsoidal shape that radiopharmaceutical is uniform distributed in them and gamma absorption fraction is calculated and recorded in the tables and the fraction of beta absorption is considered unit. While, kidney has internal organs and radioisotope is not uniform distributed in and beta absorbed fraction is not unit. Material and method: In this research, for the first time kidney is considered integrated shape and for the second time has been considered that it is consisted of three areas, pelvis, medulla and cortex. It is supposed that radiopharmaceutical is distributed in medulla. Then, beta absorbed dose is calculated in medulla and cortex using MCNPX code and is compared with integrated kidney results. Resuts: This research has been showed that beta absorbed dose from 203Hg, 166Ho and 177Lu isotopes in medulla is four times as much as dose in integrated kidney and beta dose in cortex is 0.004 to 0.012 times as much as beta dose in integrated kidney. Conclusion: Internal structure of kidney should be considered in simulation to achieve a more accurate prescribed dose. It is recommended that simulation results of three areas kidney are replaced with integrated kidney to prevent from renal toxicity.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pasciak, A; Kao, J [University of Tennessee Medical Center, Knoxville, TN (United States)

    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

  13. Absorbed Doses and Risk Estimates of (211)At-MX35 F(ab')2 in Intraperitoneal Therapy of Ovarian Cancer Patients

    DEFF Research Database (Denmark)

    Cederkrantz, Elin; Andersson, Håkan; Bernhardt, Peter

    2015-01-01

    dose associated with i.p. administration of (211)At-MX35 F(ab')2. METHODS AND MATERIALS: Patients in clinical remission after salvage chemotherapy for peritoneal recurrence of ovarian cancer underwent i.p. infusion of (211)At-MX35 F(ab')2. Potassium perchlorate was given to block unwanted accumulation...... 100 MBq/L, organ equivalent doses were less than 10% of the estimated tolerance dose. CONCLUSION: Intraperitoneal (211)At-MX35 F(ab')2 treatment is potentially a well-tolerated therapy for locally confined microscopic ovarian cancer. Absorbed doses to normal organs are low, but because the effective...

  14. 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.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  16. Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828 on the coast of Ceara, Brazil

    Directory of Open Access Journals (Sweden)

    Wagner de S. Pereira

    2010-01-01

    Full Text Available A methodology was developed for converting the activity concentration of radionuclides (Bq kg-1 into absorbed dose rate (Gy y-1, aiming an approach to environmental radioprotection based on the concept of standard dose limit. The model considers only the internal absorbed dose rate. This methodology was applied to the cubera snapper fish (Lutjanus cyanopterus, Cuvier, 1828 caught off the coast of Ceará. The natural radionuclides considered were uranium-238, radium-226, lead-210, thorium-232 and radium-228. The absorbed dose rates were calculated for individual radionuclides and the type of emitted radiation. The average dose rate due to these radionuclides was 5.36 µGy y-1, a value six orders of magnitude smaller than the threshold value of absorbed dose rate used in this study (3.65 10³ mGy y-1, and similar to that found in the literature for benthic fish. Ra-226 and U-238 contributed 67% and 22% of the absorbed dose rate, followed by Th-232 with 10%. Ra-228 and Pb-210, in turn, accounted for less than 1% of the absorbed dose rate. This distribution is somewhat different from that reported in the literature, where the Ra-226 accounts for 86% of the absorbed dose rate.Visando a radioproteção ambiental, baseada no conceito de limite de taxa de dose absorvida, foi desenvolvida uma metodologia de conversão da concentração de atividade de radionuclídeos (Bq kg-1 em taxa de dose absorvida (Gy a-1. O modelo considera apenas a taxa de dose absorvida interna. Essa metodologia foi aplicada ao peixe vermelho-caranho (Lutjanus cyanopterus, Cuvier, 1828 capturado na costa do Ceará e aos radionuclídeos naturais: urânio-238, rádio-226, chumbo-210, tório-232 e rádio-228. As taxas de dose absorvidas foram calculadas por radionuclídeo e por tipo de radiação emitida. A taxa de dose média devida a esses radionuclídeos foi de 5.36 µGy a-1, valor seis ordens de grandeza menor que o valor de limite de taxa de dose absorvida utilizada no presente

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

    Energy Technology Data Exchange (ETDEWEB)

    Aragon-Martinez, N; Hernandez-Guzman, A [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico City, DF (Mexico); Gomez-Munoz, A [Centro Medico Nacional Siglo XXI, Mexico City, DF (Mexico); 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Waldenstroem, Ann-Charlotte, E-mail: ann-charlotte.waldenstrom@oncology.gu.se [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg (Sweden); Department of Oncology, Sahlgrenska University Hospital, Gothenburg (Sweden); Olsson, Caroline [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg (Sweden); Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg (Sweden); Wilderaeng, Ulrica [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg (Sweden); Dunberger, Gail; Lind, Helena; Alevronta, Eleftheria [Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, Karolinska Institute, Stockholm (Sweden); Al-Abany, Massoud [Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, Karolinska Institute, Stockholm (Sweden); Department of Hospital Physics, Karolinska University Hospital, Stockholm (Sweden); Tucker, Susan [Department of Bioinformatics and Computational Biology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Avall-Lundqvist, Elisabeth [Department of Gynecologic Oncology, Karolinska University Hospital, Stockholm (Sweden); Johansson, Karl-Axel [Department of Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg (Sweden); Steineck, Gunnar [Division of Clinical Cancer Epidemiology, Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg (Sweden); Division of Clinical Cancer Epidemiology, Department of Oncology-Pathology, Karolinska Institute, Stockholm (Sweden)

    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.

  19. 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.

    Science.gov (United States)

    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.

  20. 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.

    Science.gov (United States)

    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.

  1. Absorbed doses received by infants subjected to panoramic dental and cephalic radiographs; Dosis absorbida recibida por infantes sometidos a radiografias dentales panoramicas y cefalicas

    Energy Technology Data Exchange (ETDEWEB)

    Carrizales, L.; Carreno, S. [Instituto Venezolano de Investigaciones Cientificas. Laboratorio Secundario de Calibracion Dosimetrica. Carretera Panamericana Km. 11. Apartado Postal 21827, Caracas (Venezuela)

    1998-12-31

    The IAEA Report No. 115 recommends that each country or region can establish levels of absorbed doses for each radiographic technique employed in diagnostic. assuming the extended and expensive of this purpose, we have been to begin in a first step with the dentistry area, in order to estimate the dose levels received at crystalline and thyroid level in infants that go to an important public institution in our country to realize panoramic and cephalic radiographs. This work will serve to justify and impel a quality assurance program in Venezuela on the dentistry area which includes aspects such as training for the medical lap referring the justification of the radiological practice, optimization of X-ray units to produce an adequate image quality that delivers to patient an absorbed dose as much lower as reasonably it can be reached without diagnostic detriment. (Author)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Pereira, Wagner de S.; Kelecom, Alphonse; Py Júnior, Delcy de Azevedo

    2008-08-01

    The uranium mining at Caetité (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 3.5×103 μGy y-1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51×100 μGy y-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. Absorbed dose in AgBr in direct film for photon energies ( < 150 keV): relation to optical density. Theoretical calculation and experimental evaluation.

    Science.gov (United States)

    Helmrot, E; Alm Carlsson, G

    1996-01-01

    In the radiological process it is necessary to develop tools so as to explore how X-rays can be used in the most effective way. Evaluation of models to derive measures of image quality and risk-related parameters is one possibility of getting such a tool. Modelling the image receptor, an important part of the imaging chain, is then required. The aim of this work was to find convenient and accurate ways of describing the blackening of direct dental films by X-rays. Since the beginning of the 20th century, the relation between optical density and photon interactions in the silver bromide in X-ray films has been investigated by many authors. The first attempts used simple quantum theories with no consideration of underlying physical interaction processes. The theories were gradually made more realistic by the introduction of dosimetric concepts and cavity theory. A review of cavity theories for calculating the mean absorbed dose in the AgBr grains of the film emulsion is given in this work. The cavity theories of GREENING (15) and SPIERS-CHARLTON (37) were selected for calculating the mean absorbed dose in the AgBr grains relative to the air collision kerma (Kc,air) of the incident photons of Ultra-speed and Ektaspeed (intraoral) films using up-to-date values of interaction coefficients. GREENING'S theory is a multi-grain theory and the results depend on the relative amounts of silver bromide and gelatine in the emulsion layer. In the single grain theory of SPIERS-CHARLTON, the shape and size of the silver bromide grain are important. Calculations of absorbed dose in the silver bromide were compared with measurements of optical densities in Ultra-speed and Ektaspeed films for a broad range (25-145 kV) of X-ray energy. The calculated absorbed dose values were appropriately averaged over the complete photon energy spectrum, which was determined experimentally using a Compton spectrometer. For the whole range of tube potentials used, the measured optical densities of the

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

    Science.gov (United States)

    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.

  6. 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.

    Science.gov (United States)

    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.

  7. Absorbed Dose Distributions in Small Copper Wire Insulation due to Multiple-Sided Irradiations by 0.4 MeV Electrons

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.; Pedersen, Walther Batsberg

    1979-01-01

    When scanned electron beams are used to crosslink polymeric insulation of wire and cable, an important goal is to achieve optimum uniformity of absorbed dose distributions. Accurate measurements of dose distributions in a plastic dosimeter simulating a typical insulating material (polyethylene....... and insulation thicknesses between 0.4 and 0.8 mm. The plastic dosimeter simulating polyethylene insulations was a thin radiochromic polyvinyl butyral film wrapped several times around the copper wire, such that when unwrapped and analyzed optically on a scanning microspectrophotometer, high-resolution radial...

  8. Measurement of absorbed radiation doses during whole body irradiation for bone marrow transplants using thermoluminescent dosimeters; Verificacao das doses de radiacao absorvidas durante a tecnica de irradiacao de corpo inteiro nos transplantes de medula ossea, por meio de dosimetros termoluminescentes

    Energy Technology Data Exchange (ETDEWEB)

    Giordani, Adelmo Jose; Segreto, Helena Cristina Comodo; Segreto, Roberto Araujo; Medeiros, Regina Bitelli; Oliveira, Jose Salvador R. de [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Setor de Radioterapia]. E-mail: adelmogiordani@ig.com.br

    2004-10-01

    The objective was to evaluate the precision of the absorbed radiation doses in bone marrow transplant therapy during whole body irradiation. Two-hundred CaSO{sub 4}:Dy + teflon tablets were calibrated in air and in 'phantom'. These tablets were randomly selected and divided in groups of five in the patients' body. The dosimetric readings were obtained using a Harshaw 4000A reader. Nine patients had their entire bodies irradiated in parallel and opposite laterals in a cobalt-60 Alcion II model, with a dose rate of 0.80 Gy/min at 80.5 cm, {l_brace}(10 ? 10) cm{sup 2} field. The dosimetry of this unit was performed using a Victoreen 500 dosimeter. For the determination of the mean dose at each point evaluated, the individual values of the tablets calibrated in air or 'phantom' were used, resulting in a build up of 2 mm to superficialize the dose at a distance of 300 cm. In 70% of the patients a variation of less than 5% in the dose was obtained. In 30% of the patients this variation was less than 10%, when values obtained were compared to the values calculated at each point. A mean absorption of 14% was seen in the head, and an increase of 2% of the administered dose was seen in the lungs. In patients with latero-lateral distance greater than 35 cm the variation between the calculated doses and the measured doses reached 30% of the desired dose, without the use of compensation filters. The measured values of the absorbed doses at the various anatomic points compared to the desired doses (theoretic) presented a tolerance of {+-} 10%, considering the existent anatomical differences and when using the individual calibration factors of the tablets. (author)

  9. KEY COMPARISON: Comparison of the standards for absorbed dose to water of the BNM-LNHB and the BIPM for 60Co γ rays

    Science.gov (United States)

    Allisy-Roberts, P. J.; Burns, D. T.; Kessler, C.; Delaunay, F.; Leroy, E.

    2005-01-01

    A comparison of the standards for absorbed dose to water of the Bureau National de Métrologie - Laboratoire National Henri Becquerel (BNM-LNHB), Saclay, France and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co radiation under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result expressed as a ratio of the BNM-LNHB and the BIPM standards for absorbed dose to water is 0.9970 (0.0053). The degrees of equivalence between the BNM-LNHB and the other participants in this comparison have been calculated and the results are given in the form of a matrix for the 12 national metrology institutes (NMIs) that have taken part in the ongoing comparison for absorbed dose to water. A graphical presentation is also given. 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 Section I of the Consultative Committee for Ionizing Radiation (CCRI(I)), according to the provisions of the Mutual Recognition Arrangement (MRA).

  10. Comparison of the standards for absorbed dose to water of the NRC and the BIPM for {sup 60}Co gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C.; Allisy-Roberts, P.J.; Burns, D.T. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); McCaffrey, J.P.; McEwen, M.R.; Ross, C.K. [National Research Council of Canada, Ottawa (Canada)

    2010-06-15

    A comparison of the standards for absorbed dose to water of the National Research Council of Canada (NRC) and of the Bureau International des Poids et Mesures (BIPM) was carried out in the {sup 60}Co radiation beam of the BIPM in May 2009 under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result, based on the calibration coefficients for two transfer standards and expressed as a ratio of the NRC and the BIPM standards for absorbed dose to water, is 0.9980(52). This result replaces the 1998 NRC value of 0.9976(51) in this key comparison. The degrees of equivalence between the NRC and the other participants in this comparison have been calculated and the results are given in the form of a matrix for the ten national metrology institutes (NMIs) with published results that have taken part in the ongoing comparison for absorbed dose to water. A graphical presentation is also given. (authors)

  11. Absorbed dose rate due to intake of natural radionuclides by Tilapia fish (Tilapia nilotica, Linnaeus, 1758) estimated near uranium anomaly at Santa Quiteria, Ceara, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de [Industrias Nucleares do Brasil S.A. (INB), Pocos de Caldas, MG (Brazil). Coordenacao de Protecao Radiologica. Unidade de Tratamento de Minerios], E-mail: wspereira@inb.gov.br; Kelecom, Alphonse [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Ciencia Ambiental; Py Junior, Delcy de Azevedo [Industrias Nucleares do Brasil S.A. (INB), Caetite, BA (Brazil). Coordenacao de Protecao Radiologica. Unidade de Concentrado de Uranio], E-mail: Delcy@inb.gov.br

    2007-07-01

    The uranium mining at Santa Quiteria (Santa Quiteria Unit - USQ) is in its environmental licensing phase. Aiming to estimate the radiological environmental impact of the USQ, a monitoring program is underway. However, radioprotection of biota is not explicitly mentioned in Brazilian norms. In order to preserve the biota of the deleterious effects from radiation and to behave in a pro-active way as expected by licensing organs, the present work aims to use an environmental protection methodology, based on the calculation of absorbed dose rate in biota. Thus, selected biomarker was the fish tilapia (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). Since there are no exposition limits for biota, in Brazil, the value proposed by the Department of Energy (DOE) of the United States of 3.5 x 10{sup 3} {mu}Gy/y has been used. The derived absorbed dose rate calculated for tilapia was 2.76 x 10{sup 0} {mu}Gy/y, that is less than 0.1 % of the limit established by DOE. The critical radionuclide was U-238, with 99% of the absorbed dose rate. This value of 0.1% of the limit allows to state that in pre-operational conditions analyzed natural radionuclides do not represent a radiological problem to the biota. (author)

  12. Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Power, S.; Mirza, M.; Thakorlal, A.; Ganai, B.; Gavagan, L. D.; Given, M. F.; Lee, M. J., E-mail: mlee@rcsi.ie [Beaumont Hospital, Imaging and Interventional Radiology Department (Ireland)

    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.

  13. Calculation of absorbed doses in sphere volumes around the Mammosite using the Monte Carlo simulation code MCNPX; Calculo de dosis absorbida en volumenes esfericos alrededor del Mammosite utilizando el codigo de simulacion Monte Carlo MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E. L. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2008-07-01

    The objective of this study is to investigate the changes observed in the absorbed doses in mammary gland tissue when irradiated with a equipment of high dose rate known as Mammosite and introducing material resources contrary to the tissue that constitutes the mammary gland. The modeling study is performed with the code MCNPX, 2005 version, the equipment and the mammary gland and calculating the absorbed doses in tissue when introduced small volumes of air or calcium in the system. (Author)

  14. Absorbed radiation doses in women undergone to PET-CT exams for cancer diagnosis; Dose absorvida e efetiva em mulheres submetidas a exames de PET-CT para diagnostico oncologico

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Priscila do Carmo; Bernardes, Felipe Dias; Mamede, Marcelo, E-mail: pridili@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Oliveira, Paulo Marcio Campos de; Silva, Teogenes Augusto da [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Mourao FIlho, Arnaldo Prata [Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil)

    2014-07-01

    The absorbed dose in several organs and the effective dose in patients submitted to PET-CT exams with the radiopharmaceutical {sup 18}F-FDG were assessed. The ICRP-106 biokinetic model and thermoluminescent detectors in a anthropomorphic phantom were used. The use of the PET-CT image acquisition protocol, with the CT protocol for anatomical mapping, showed that 60% of effective dose was from the radiotracer administration, being the effective dose values for a female patient of (5.80 ± 1.57) mSv. In conclusion, patient doses can be reduced by using appropriate imaging acquisition in {sup 18}F-FDG PET-CT examinations and promoting the compliance with the radiation protection principles. (author)

  15. Evaluation of the dose absorbed by the thyroid of patients undergoing treatment of Graves disease;Avaliacao da dose absorvida pela tireoide de pacientes submetidos ao tratamento da doenca de Graves

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Tiago L.; Filho, Joao A. [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil). Dept. de Fisica; Silva, Jose M.F. da [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2009-07-01

    The radioiodine is used as complementary treatment of thyroid cancer and as first choice for the treatment of Graves' disease, being efficient, safe and easy administration, but without there is a protocol defined. This work was evaluated the thyroid absorbed dose from its mass and maximum uptake of I-131 obtained in the examination of diagnostic radiology of radiotherapeutic patients undergoing treatment of Graves' disease. Based on the results, it is observed that the thyroid absorbed dose, as much in terms of mass as the maximum uptake of I-131 for different values of administered activity, varies significantly. The analysis of these parameters is an excellent indicator for the pre-define quantity of radionuclide that is administered to the patient in terms of the radiation dose required to achieve an efficient therapeutic treatment. Moreover, it was observed that the thyroid absorbed dose depends on the degree of pathology of the disease, its mass and of the maximum uptake of I-131. (author)

  16. Quantitative assessment of selective in-plane shielding of tissues in computed tomography through evaluation of absorbed dose and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Geleijns, J.; Veldkamp, W.J.H. [Leiden University Medical Center, Radiology Department, ZA Leiden (Netherlands); Salvado Artells, M.; Lopez Tortosa, M. [Universitat Rovira i Virgili, Facultat de Medicina i Ciencies de la Salut, Departament de Ciencies Mediques Basiques, Reus, Tarragona (Spain); Calzado Cantera, A. [Universidad Complutense de Madrid, Departamento de Radiologia, Madrid (Spain)

    2006-10-15

    This study aimed at assessment of efficacy of selective in-plane shielding in adults by quantitative evaluation of the achieved dose reduction and image quality. Commercially available accessories for in-plane shielding of the eye lens, thyroid and breast, and an anthropomorphic phantom were used for the evaluation of absorbed dose and image quality. Organ dose and total energy imparted were assessed by means of a Monte Carlo technique taking into account tube voltage, tube current, and scanner type. Image quality was quantified as noise in soft tissue. Application of the lens shield reduced dose to the lens by 27% and to the brain by 1%. The thyroid shield reduced thyroid dose by 26%; the breast shield reduced dose to the breasts by 30% and to the lungs by 15%. Total energy imparted (unshielded/shielded) was 88/86 mJ for computed tomography (CT) brain, 64/60 mJ for CT cervical spine, and 289/260 mJ for CT chest scanning. An increase in image noise could be observed in the ranges were bismuth shielding was applied. The observed reduction of organ dose and total energy imparted could be achieved more efficiently by a reduction of tube current. The application of in-plane selective shielding is therefore discouraged. (orig.)

  17. Differences among Monte Carlo codes in the calculations of voxel S values for radionuclide targeted therapy and analysis of their impact on absorbed dose evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Pacilio, M.; Lanconelli, N.; Lo Meo, S.; Betti, M.; Montani, L.; Torres Aroche, L. A.; Coca Perez, M. A. [Department of Medical Physics, Azienda Ospedaliera S. Camillo Forlanini, Piazza Forlanini 1, Rome 00151 (Italy); Department of Physics, Alma Mater Studiorum University of Bologna, Viale Berti-Pichat 6/2, Bologna 40127 (Italy); Department of Medical Physics, Azienda Ospedaliera S. Camillo Forlanini, Piazza Forlanini 1, Rome 00151 (Italy); Department of Medical Physics, Azienda Ospedaliera Sant' Andrea, Via di Grotarossa 1035, Rome 00189 (Italy); Department of Medical Physics, Center for Clinical Researches, Calle 34 North 4501, Havana 11300 (Cuba)

    2009-05-15

    Several updated Monte Carlo (MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim of this work is to analyze the differences in the calculations obtained by different MC codes and their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S values for monoenergetic sources (electrons and photons) and different radionuclides ({sup 90}Y, {sup 131}I, and {sup 188}Re) were calculated. Simulations were performed in soft tissue. Three general-purpose MC codes were employed for simulating radiation transport: MCNP4C, EGSnrc, and GEANT4. The data published by the MIRD Committee in Pamphlet No. 17, obtained with the EGS4 MC code, were also included in the comparisons. The impact of the differences (in terms of voxel S values) among the MC codes was also studied by convolution calculations of the absorbed dose in a volume of interest. For uniform activity distribution of a given radionuclide, dose calculations were performed on spherical and elliptical volumes, varying the mass from 1 to 500 g. For simulations with monochromatic sources, differences for self-irradiation voxel S values were mostly confined within 10% for both photons and electrons, but with electron energy less than 500 keV, the voxel S values referred to the first neighbor voxels showed large differences (up to 130%, with respect to EGSnrc) among the updated MC codes. For radionuclide simulations, noticeable differences arose in voxel S values, especially in the bremsstrahlung tails, or when a high contribution from electrons with energy of less than 500 keV is involved. In particular, for {sup 90}Y the updated codes showed a remarkable divergence in the bremsstrahlung region (up to about 90% in terms of voxel S values) with respect to the EGS4 code. Further, variations were observed up to about 30%, for small source-target voxel distances, when low-energy electrons cover an important part of the emission spectrum of the radionuclide

  18. Evaluation of the lens absorbed dose of MVCT and kV-CBCT use for IMRT to the nasopharyngeal cancer patients

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Won; Kim, Cheol Chong; Park, Su Yeon; Song, Ki Weon [Dept. of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of)

    2013-09-15

    Quantitative comparative evaluation of the difference in eye lens absorbed dose when measured by MVCT and kV-CBCT, though such a dose was not included in the original IMRT treatment plan for the nasopharyngeal cancer patient. We used CT (Lightspeed Ultra 16, General Electric, USA) against an Anderson rando phantom (Alderson Research Laboratories Inc, USA) and established the plan for tomotherapy treatment (Tomotherapy, Inc, USA) and linear accelerator treatment (Pinnacle 8.0, Philips Medicle System) for the achieved CT images on the same condition with the nasopharyngeal cancer patient treatment plan. Then, align the thermoluminescence dosimeter (TLD100 Harshaw, USA) with the eye lens, shot the lens with Tomotherapy MVCT under 3 conditions (Fine, Normal, and Coarse), and shot both lenses with kV-CBCT under 2 conditions (Low Dose Head and Standard Dose Head) 3 times each. When we analyzed the eye lens absorbed dose according to MVCT and kV-CBCT images by using both Tomotherapy and Pinacle 8.0, we achieved the following result; According to Tomotherapy MVCT, RT 0.8257 cGy in the Coarse mode, LT 0.8137 cGy, RT 1.089 cGy and LT 1.188 cGy in the Normal mode, and RT 2.154 cGy and LT 2.082 cGy in the Fine mode. According to Pinacle 8.0 kV-CBCT, RT 0.2875 cGy and LT 0.1676 cGy in the Standard Dose mode and RT 0.1648 cGy and LT 0.1212 cGy in the Low-Dose mode. In short, the MVCT result was significantly different from that of kV-CBCT, up to 20 times. We think kV-CBCT is more effective for reducing the amount of radiation which a patient is receiving during intensity modulated radiation treatment for other purposes than treatment than MVCT, when we consider the absorbed dose only from the viewpoint of image-guided radiation therapy. Besides, we understood the amount of radiation is too sensitive to the shooting condition, even when we use the same equipment.

  19. The influence of the patient's posture on organ and tissue absorbed doses caused by radiodiagnostic examinations; Influencia da postura do paciente na dose absorvida em orgaos e tecidos causada por exames radiologicos

    Energy Technology Data Exchange (ETDEWEB)

    Cassola, Vagner F.; Kramer, Richard; Khoury, Helen J.; Lira, Carlos A.B.O., E-mail: vagner.cassola@gmail.co [Universidade Federal de Pernambuco (DEN/UFPE), Recife (Brazil). Dept. de Energia Nuclear

    2011-07-01

    Due to the gravitational force, organ positions and subcutaneous fat distribution change when a standing person lies down on her/his back, which is called 'supine posture'. Both postures, standing and supine, are very common in X-ray diagnosis, however, phantoms used for the simulation of patients for organ and tissue absorbed dose assessments normally represent humans either in standing or in supine posture. Consequently, the exposure scenario simulated sometimes does not match the real X-ray examination with respect to the patient's posture. Using standing and supine versions of mesh-based female and male adult phantoms, this study investigates the 'posture-effect' on organ and tissue absorbed doses for radiographs of the pelvis and the lumbar spine in order to find out if the errors from simulating the false posture are significant. (author)

  20. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Farah, Khaled, E-mail: kafarah@gmail.com [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); ISTLS, University of Sousse (Tunisia); Hosni, Faouzi [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); Academie Militaire de Fondouk Jedid, 8012 Nabeul (Tunisia); Mejri, Arbi [Unité de recherche: Maîtrise et développement des techniques nucléaires à caractère pacifique, Centre National des Sciences et Technologie Nucléaires, 2020 Sidi-Thabet (Tunisia); Boizot, Bruno [Laboratoire des Solides Irradiés, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Hamzaoui, Ahmed Hichem [Centre National de Recherche en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Ben Ouada, Hafedh [Laboratoire des Interfaces et Matériaux Avancés, Faculté des Sciences, University of Monastir, Avenue de l’environnement, 5019 Monastir (Tunisia)

    2014-03-15

    Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO{sub 3} and NaNO{sub 3} with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy.

  1. Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

    Science.gov (United States)

    Farah, Khaled; Hosni, Faouzi; Mejri, Arbi; Boizot, Bruno; Hamzaoui, Ahmed Hichem; Ben Ouada, Hafedh

    2014-03-01

    Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO3 and NaNO3 with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1-250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV-Vis range of the Ag-Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, P. Avilés, E-mail: paz.aviles@ciemat.es; Aubineau-Lanièce, I.; Lourenço, V.; Vermesse, D.; Cutarella, D. [CEA, LIST, Laboratoire National Henri Becquerel, 91191 Gif-sur-Yvette (France)

    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

  3. 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.

    Science.gov (United States)

    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.

  4. 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.

    Science.gov (United States)

    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.

  5. Quantification of micronuclei in blood lymphocytes of patients exposed to gamma radiation for dose absorbed assessment; Quantificacao de micronucleos em linfocitos de pacientes expostas a radiacao gama para a avaliacao da dose absorvida

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Isvania Maria Serafim da Silva

    2003-02-15

    Dose assessment in an important step to evaluate biological effects as a result of individual exposure to ionizing radiation. The use of cytogenetic dosimetry based on the quantification of micronuclei in lymphocytes is very important to complement physical dosimetry, since the measurement of absorbed dose cannot be always performed. In this research, the quantification of micronuclei was carried out in order to evaluate absorbed dose as a result of radiotherapy with {sup 60}Co, using peripheral blood samples from 5 patients with cervical uterine cancer. For this purpose, an aliquot of whole blood from the individual patients was added in culture medium RPMI 1640 supplemented with fetal calf serum and phytohaemagglutinin. The culture was incubated for 44 hours. Henceforth, cytochalasin B was added to block the dividing lymphocytes in cytokinesis. The culture was returned to the incubator for further of 28 hours. Thus, cells were harvested, processed and analyzed. Values obtained considering micronuclei frequency after pelvis irradiation with absorption of 0,08 Gy and 1,8 Gy were, respectively, 0,0021 and 0,052. These results are in agreement with some recent researches that provided some standard values related to micronuclei frequency induced by gamma radiation exposure in different exposed areas for the human body. The results presented in this report emphasizes biological dosimetry as an important tool for dose assessment of either total or partial-body exposure to ionizing radiation, mainly in retrospective dose investigation. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Park, S [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of); Kim, H [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Ye, S [Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul (Korea, Republic of); Department of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of); Program in Biomedical Radiation Sciences, Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon (Korea, Republic of)

    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. Absorbed doses received by patients submitted to chest radiographs in hospitals of the city of Sao Paulo, Brazil; Doses absorvidas pelos pacientes submetidos a radiografias toracicas em hospitais do municipio de Sao Paulo

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Marcelo Baptista de

    2000-07-01

    Medical irradiation contributes with a significant amount to the dose received by the population. Here, this contribution was evaluated in a survey of absorbed doses received by patients submitted to chest radiological examinations (postero-anterior (PA) and lateral (LAT) projections) in hospitals of the city of Sao Paulo. Due to the variety of equipment and procedures used in radiological examinations, a selection of hospitals was made (12, totalizing 27 X-ray facilities), taking into account their representativeness as medical institutions in the city, in terms of characteristics and number of radiographs carried out. An anthropomorphic phantom, provided with thermoluminescent dosemeters (TLD-1 00), was irradiated simulating the patient, and the radiographic image quality was evaluated. Absorbed doses were determined to the thoracic region (entrance and exit skin and lung doses), and to some important organs from the radiation protection point of view (lens of the eye, thyroid and gonads). The great variation on the exposure parameters (kV, mA.s, beam size) leads to a large interval of entrance skin doses-ESD (coefficients of variation, CV, of 60% and 76%, for PA and LAT projections, respectively, were found) and of organ doses (CV of 60% and 46%. for thyroid and lung respectively). Mean values of ESD for LAT and PA projections were 0.22 and 0.98 mGy, respectively. The average absorbed doses per exam (PA and LAT) to thyroid and lung, 0.15 and 0.24 mGy respectively,showed that the thyroid was irradiated by the primary beam in many cases. Values of lens of the eye and gonad absorbed doses were below 30 {mu}Gy. Comparison of the lung doses obtained in this study with values in the literature, calculated by Monte Carlo simulation, showed good agreement. On the other hand, the comparison shows significant differences in the dose values to organs outside the chest region (thyroid, lens of eye and gonads). The effective dose calculated for a chest examination, PA and

  8. A Minute Dose of 14C-b-Carotene is Absorbed and Converted to Retinoids in Humans

    Science.gov (United States)

    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...

  9. Image-Based Assessment and Clinical Significance of Absorbed Radiation Dose to Tumor in Repeated High-Dose {sup 131}I Anti-CD20 Monoclonal Antibody (Rituximab) Radioimmunotherapy for Non-Hodgkin's Lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Byung Hyun; Kim, Kyeong Min; Woo, Sang Keun; Choi, Tae Hyun; Kang, Hye Jin; Oh, Dong Hyun; Kim, Byeong Il; Choen, Gi Jeong; Choi, Chang Woon; Lim, Sang Moo [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2009-02-15

    We assessed the absorbed dose to the tumor (Dose tumor) by using pretreatment FDG-PET and whole-body (WB) planar images in repeated radioimmunotherapy (RIT) with {sup 131}I rituximab for NHL. Patients with NHL (n=4) were administered a therapeutic dose of {sup 131}I rituximab. Serial WB planar images after RIT were acquired and overlaid to the coronal maximum intensity projection (MIP) PET image before RIT. On registered MIP PET and WB planar images, 2D-ROIs were drawn on the region of tumor (n=7) and left medial thigh as background, and Dosetumor was calculated. The correlation between Dosetumor and the CT-based tumor volume change after RIT was analyzed. The differences of Dosetumor and the tumor volume change according to the number of RIT were also assessed. The values of absorbed dose were 397.7{+-}646.2cGy (53.0{approx}2853.0cGy). The values of CT-based tumor volume were 11.3{+-}9.1 cc (2.9{approx}34.2cc), and the % changes of tumor volume before and after RIT were -29.8{+-}44.3% (-100.0%{approx}+42.5%), respectively. Dosetumor and the tumor volume change did not show the linear relationship (p>0.05). Dosetumor and the tumor volume change did not correlate with the number of repeated administration (p>0.05). We could determine the position and contour of viable tumor by MIP PET image. And, registration of PET and gamma camera images was possible to estimate the quantitative values of absorbed dose to tumor.

  10. Determination of absorbed dose in water at the reference point d(r0, theta0) for an 192Ir HDR brachytherapy source using a Fricke system.

    Science.gov (United States)

    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

  11. Code intercomparison and benchmark for muon fluence and absorbed dose induced by an 18-GeV electron beam after massive iron shielding

    CERN Document Server

    Fasso, Alberto; Ferrari, Anna; Mokhov, Nikolai V; Mueller, Stefan E; Nelson, Walter Ralph; Roesler, Stefan; Sanami, Toshiya; Striganov, Sergei I; Versaci, Roberto

    2015-01-01

    In 1974, Nelson, Kase, and Svenson published an experimental investigation on muon shielding using the SLAC high energy LINAC. They measured muon fluence and absorbed dose induced by a 18 GeV electron beam hitting a copper/water beam dump and attenuated in a thick steel shielding. In their paper, they compared the results with the theoretical mode ls available at the 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 will then be compared between the codes, and with the SLAC data.

  12. SU-F-19A-02: Comparison of Absorbed Dose to Water Standards for HDR Ir-192 Brachytherapy Between the LCR, Brazil and NRC, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Salata, C; David, M; Almeida, C de [Universidade do Estado do Rio de Janeiro, Rio De Janeiro, RJ (Brazil); El Gamal, I; Cojocaru, C; Mainegra-Hing, E; McEwen, M [National Research Council, Ottawa, ON (Canada)

    2014-06-15

    Purpose: To compare absorbed dose to water standards for HDR brachytherapy dosimetry developed by the Radiological Science Laboratory of Rio de Janeiro State University (LCR) and the National Research Council, Canada (NRC). Methods: The two institutions have separately developed absorbed dose standards based on the Fricke dosimetry system. There are important differences between the two standards, including: preparation and read-out of the Fricke solution, irradiation geometry of the Fricke holder in relation to the Ir-192 source, and determination of the G-value to be used at Ir-192 energies. All measurements for both standards were made directly at the NRC laboratory (i.e., no transfer instrument was used) using a single Ir-192 source (microSelectron v2). In addition, the NRC group has established a self-consistent method to determine the G-value for Ir-192, based on an interpolation between G-values obtained at Co-60 and 250kVp X-rays, and this measurement was repeated using the LCR Fricke solution to investigate possible systematic uncertainties. Results: G-values for Co-60 and 250 kVp x-rays, obtained using the LCR Fricke system, agreed with the NRC values within 0.5 % and 1 % respectively, indicating that the general assumption of universal G-values is appropriate in this case. The standard uncertainty in the determination of G for Ir-192 is estimated to be 0.6 %. For the comparison of absorbed dose measurements at the reference point for Ir-192 (1 cm depth in water, perpendicular to the seed long-axis), the ratio Dw(NRC)/Dw(LCR) was found to be 1.011 with a combined standard uncertainty of 1.7 %, k=1. Conclusion: The agreement in the absorbed dose to water values for the LCR and NRC systems is very encouraging. Combined with the lower uncertainty in this approach compared to the present air-kerma approach, these results reaffirm the use of Fricke solution as a potential primary standard for HDR Ir-192 brachytherapy.

  13. Update on the Code Intercomparison and Benchmark for Muon Fluence and Absorbed Dose Induced by an 18 GeV Electron Beam After Massive Iron Shielding

    Energy Technology Data Exchange (ETDEWEB)

    Fasso, A. [SLAC; Ferrari, A. [CERN; Ferrari, A. [HZDR, Dresden; Mokhov, N. V. [Fermilab; Mueller, S. E. [HZDR, Dresden; Nelson, W. R. [SLAC; Roesler, S. [CERN; Sanami, t.; Striganov, S. I. [Fermilab; Versaci, R. [Unlisted, CZ

    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.

  14. Evaluation of variation of voltage (kV) absorbed dose in chest CT scans; Avaliacao da variacao da tensao (kV) na dose absorvida em varreduras de TC torax

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Bruna G.A.; Mourao, Arnaldo P., E-mail: brunabgam@gmail.com [Centro Federal de Educacao Tecnologica de Minas Gerais (CENEB/CEFET-MG), Belo Horionte, MG, (Brazil)

    2013-07-01

    Computed tomography (CT) is one of the most important diagnostic techniques images today. The increasing utilization of CT implies a significant increase of population exposure to ionizing radiation. Optimization of practice aims to reduce doses to patients because the image quality is directly related to the diagnosis. You can decrease the amount of dose to the patient, and maintain the quality of the image. There are several parameters that can be manipulated in a CT scan and these parameters can be used to reduce the energy deposited in the patient. Based on this, we analyzed the variation of dose deposited in the lungs, breasts and thyroid, by varying the supply voltage of the tube. Scans of the thorax were performed following the protocol of routine chest with constant and variable current for the same applied voltage. Moreover, a female phantom was used and thermoluminescent dosimeters (TLD-100), model bat, were used to record the specific organ doses. Scans were performed on a GE CT scanner, model 64 Discovery channels. Higher doses were recorded for the voltage of 120 kV with 200 mAs in the lungs (22.46 mGy) and thyroid (32.22 mGy). For scans with automatic mAs, variable between 100 and 440, this same tension contributed to the higher doses. The best examination in terms of the dose that was used with automatic 80 kV mAs, whose lungs and thyroid received lower dose. For the best breast exam was 100 kV. Since the increase in the 80 kV to 100 kV no impact so much the dose deposited in the lungs, it can be concluded that lowering the applied voltage to 100 kV resulted in a reduction in the dose absorbed by the patient. These results can contribute to optimizing scans of the chest computed tomography.

  15. 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

    Science.gov (United States)

    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

  16. The absorbed dose to the blood is a better predictor of ablation success than the administered {sup 131}I activity in thyroid cancer patients

    Energy Technology Data Exchange (ETDEWEB)

    Verburg, Frederik A.; Lassmann, Michael; Reiners, Christoph; Haenscheid, Heribert [University of Wuerzburg, Department of Nuclear Medicine, Wuerzburg (Germany); Maeder, Uwe [University of Wuerzburg, Comprehensive Cancer Center Mainfranken, Wuerzburg (Germany); Luster, Markus [University of Ulm, Department of Nuclear Medicine, Ulm (Germany)

    2011-04-15

    The residence time of {sup 131}I in the blood is likely to be a measure of the amount of {sup 131}I that is available for uptake by thyroid remnant tissue and thus the radiation absorbed dose to the target tissue in {sup 131}I ablation of patients with differentiated thyroid cancer (DTC). This hypothesis was tested in an investigation on the dependence of the success rate of radioiodine remnant ablation on the radiation absorbed dose to the blood (BD) as a surrogate for the amount of {sup 131}I available for iodine-avid tissue uptake. This retrospective study included 449 DTC patients who received post-operative {sup 131}I ablation in our centre in the period from 1993 to 2007 and who returned to us for diagnostic whole-body scintigraphy. The BD was calculated based on external dose rate measurements using gamma probes positioned in the ceiling. Success of ablation was defined as a negative diagnostic {sup 131}I whole-body scan and undetectable thyroglobulin levels at 6 months follow-up. Ablation was successful in 56.6% of the patients. The rate of successful ablation correlated significantly with BD but not with the administered activity. Patients with blood doses exceeding 350 mGy (n = 144) had a significantly higher probability for successful ablation (63.9%) than the others (n = 305, ablation rate 53.1%, p = 0.03). In contrast, no significant dependence of the ablation rate on the administered activity was observed. The BD is a more powerful predictor of ablation success than the administered activity. (orig.)

  17. Evaluation of the absorbed dose to the lungs due to Xe{sup 133} and Tc{sup 99m} (MAA); Evaluacion de la dosis absorbida en los pulmones debido al Xe{sup 133} y Tc{sup 99m} (MAA)

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez A, M.; Murillo C, F.; Castillo D, C.; Sifuentes D, Y.; Sanchez S, P. [Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Trujillo (Peru); Rojas P, E. [Instituto Peruano de Energia Nuclear, Av. Canada 1470, Lima (Peru); Marquez P, F., E-mail: marvva@hotmail.com [Instituto Nacional de Enfermedades Neoplasicas, Av. Angamos 2520, Lima (Peru)

    2015-10-15

    The absorbed dose in lungs of an adult patient has been evaluated using the biokinetics of radiopharmaceuticals containing Xe{sup 133} or Tc{sup 99m} (MAA). The absorbed dose was calculated using the MIRD formalism, and the Cristy-and Eckerman lungs model. The absorbed dose in the lungs due to {sup 133}Xe is 0.00104 mGy/MBq. Here, the absorbed dose due to remaining tissue, included in the {sup 133}Xe biokinetics is not significant. The absorbed dose in the lungs, due Tc{sup 99m} (MAA), is 0.065 mGy/MBq. Approximately, 4.6% of the absorbed dose is due to organs like liver, kidneys, bladder, and the rest of tissues, included in the Tc{sup 99m} biokinetics. Here, the absorbed dose is very significant to be overlooked. The dose contribution is mainly due to photons emitted by the liver. (Author)

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

    Science.gov (United States)

    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.

  19. Assessment of absorbed dose and therapeutic response of tumor in repeated high-dose I-131 anti-CD20 monoclonal antibody (rituximab) radioimmunotherapy for non-Hodgkin's lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Byung Hyun; Lim, Sang Moo; Kim, Kyeong Min [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)] (and others)

    2007-07-01

    We assessed the therapeutic dose absorbed to the tumor and response in repeated RIT with I-131 rituximab for NHL. Patients with NHL (n=6) were administered a therapeutic dose of I-131 rituximab (192.527.0 mCi). The number of repeated administration was 3 for all patients. Total 12 measurable tumor regions were assessed at the time of each RIT. Whole-body (WB) planar images with anterior and posterior views were acquired sequentially at 5 min, 5hr, 24hr, 48hr, and 72hr post-injection using gamma camera. F-18-FDG PET/CT was performed before (within 7 days) and after (on Day 30) RIT. From PET/CT image acquired before RIT, maximum intensity projection (MIP) image of coronal view was acquired. Serial WB planar images were overlaid to the coronal MIP PET image, respectively, by means of registration using 4 fiducial marks (bilateral shoulder and buttock) implemented in AMIDE software. On registered MIP PET and WB planar images, both 2D-ROIs were drawn on the region of tumor and background nearby tumor. The shape of 2D-ROI of tumor was determined from the MIP PET image. The volume of tumor was measured from the CT image, the % change of tumor volume before and after RIT was used in evaluation of the therapeutic response. The values of CT-based tumor volume were 8.216.3cc. The values of absorbed dose for tumor and the % changes of tumor volume before and after RIT were 231.8603.0rad, and 55.548.7%, respectively, and did not show the linear relationship (r=0.2787). The values of absorbed dose for tumor and the % changes of tumor volume did not correlate with the number of repeated administration (p>0.05, ANOVA). Aligning PET and planar images could estimate the quantitative values of absorbed dose to tumor. The data suggest that repeated RIT with I-131 rituximab is necessary for NHL, because single-RIT is insufficient to achieve remission of disease.

  20. 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

    Energy Technology Data Exchange (ETDEWEB)

    Gutiérrez Castillo, J. G., E-mail: jggc59@hotmail.com [Departamento de Física, Hospital de Oncología, IMSS, CMN Siglo XXI, Cuauhtémoc 330 Col. Doctores (Mexico); Álvarez Romero, J. T., E-mail: trinidad.alvarez@inin.gob.mx, E-mail: fisarmandotorres@gmail.com, E-mail: victor.tovar@inin.gob.mx; Calderón, A. Torres, E-mail: trinidad.alvarez@inin.gob.mx, E-mail: fisarmandotorres@gmail.com, E-mail: victor.tovar@inin.gob.mx; M, V. Tovar, E-mail: trinidad.alvarez@inin.gob.mx, E-mail: fisarmandotorres@gmail.com, E-mail: victor.tovar@inin.gob.mx [SSDL, Departamento de Metrología ININ, Salazar, Estado de México 15245 (Mexico)

    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%.

  1. Assessment of Brain absorbed X-ray dose during CT- Scan using ImPACT software in Tehran Univeristy hospitals

    Directory of Open Access Journals (Sweden)

    Khalilpour M

    2009-07-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 st1":*{behavior:url(#ieooui } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: CT scan was first introduced into clinical practice in 1972, and since then has grown into one of the predominant diagnostic procedures. In 1998, the UK National Radiological Protection Board reported that 20% of the national collective dose from medical X-ray examinations derived from CT-scans, although it represented only 2% of all X- ray examinations the aim of this study was to determine the X-ray dosage received by patients in brain CT scan."n"n Methods: In this work, we have estimated patient dose arising from CT examination of brain in five hospitals in Tehran. Organ and effective doses were estimated for 150 patients who underwent CT examination of brain. "ImPACT" version 0.99v was used to estimate organ and effective dose. Brain examinations were performed with fixed Kvp, mAs and T (slice thickness for each scanner. "n"n Results: Patients, who were scanned by CT of emam Khomeini center (Toshiba Xvision /EX Scanner, received maximum organ dose (brain and minimum organ dose was delivered to patients who were scanned by CT of amir alam center (Toshiba Xvision /EX Scanner. Maximum effective dose was 1.7 mSv acquired in this study for emam Khomeini haspital, smaller than

  2. Radioiodine therapy in Graves' disease based on tissue-absorbed dose calculations: effect of pre-treatment thyroid volume on clinical outcome

    Energy Technology Data Exchange (ETDEWEB)

    Reinhardt, Michael J.; Joe, Alexius Y.; Mallek, Dirk von; Ezziddin, Samer; Palmedo, Holger [Department of Nuclear Medicine, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Brink, Ingo [Department of Nuclear Medicine, University Hospital of Freiburg (Germany); Krause, Thomas M. [Department of Nuclear Medicine, Inselspital Bern (Switzerland)

    2002-09-01

    This study was performed with three aims. The first was to analyse the effectiveness of radioiodine therapy in Graves' disease patients with and without goitres under conditions of mild iodine deficiency using several tissue-absorbed doses. The second aim was to detect further parameters which might be predictive for treatment outcome. Finally, we wished to determine the deviation of the therapeutically achieved dose from that intended. Activities of 185-2,220 MBq radioiodine were calculated by means of Marinelli's formula to deliver doses of 150, 200 or 300 Gy to the thyroids of 224 patients with Graves' disease and goitres up to 130 ml in volume. Control of hyperthyroidism, change in thyroid volume and thyrotropin-receptor antibodies were evaluated 15{+-}9 months after treatment for each dose. The results were further evaluated with respect to pre-treatment parameters which might be predictive for therapy outcome. Thyroidal radioiodine uptake was measured every day during therapy to determine the therapeutically achieved target dose and its coefficient of variation. There was a significant dose dependency in therapeutic outcome: frequency of hypothyroidism increased from 27.4% after 150 Gy to 67.7% after 300 Gy, while the frequency of persistent hyperthyroidism decreased from 27.4% after 150 Gy to 8.1% after 300 Gy. Patients who became hypothyroid had a maximum thyroid volume of 42 ml and received a target dose of 256{+-}80 Gy. The coefficient of variation for the achieved target dose ranged between 27.7% for 150 Gy and 17.8% for 300 Gy. When analysing further factors which might influence therapeutic outcome, only pre-treatment thyroid volume showed a significant relationship to the result of treatment. It is concluded that a target dose of 250 Gy is essential to achieve hypothyroidism within 1 year after radioiodine therapy in Graves' disease patients with goitres up to 40 ml in volume. Patients with larger goitres might need higher doses

  3. Comparison between Radiology Science Laboratory, Brazil (LCR) and National Research Council, Canada (NRC) of the absorbed dose in water using Fricke dosimetry; Comparacao entre o LCR/Brasil e o NRC/Canada da dose absorvida na agua usando a dosimetria Fricke

    Energy Technology Data Exchange (ETDEWEB)

    Salata, Camila; David, Mariano Gazineu; Almeida, Carlos Eduardo de [Universidade do Estado do Rio de Janeiro (UERJ/LCR), Rio de Janeiro (Brazil). Lab. de Ciencias Radiologicas; El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcom, E-mail: mila.salata@gmail.com [National Research Council, Ottawa (Canada)

    2014-07-01

    The absorbed dose to water standards for HDR brachytherapy dosimetry developed by the Radiology Science Laboratory, Brazil (LCR) and the National Research Council, Canada (NRC), were compared. The two institutions have developed absorbed dose standards based on the Fricke dosimetry system. There are significant differences between the two standards as far as the preparation and readout of the Fricke solution and irradiation geometry of the holder. Measurements were done at the NRC laboratory using a single Ir-192 source. The comparison of absorbed dose measurements was expressed as the ratio Dw(NRC)/Dw(LCR), which was found to be 1.026. (author)

  4. Taking into account absorbed doses in tooth enamel due to internal irradiation of human body by radioactive cesium isotopes at analysis EPR dosimetry data: Calculation by Monte-Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Borysheva, N. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249020 (Russian Federation); Ivannikov, A. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249020 (Russian Federation)], E-mail: Ivannikov-Alexander@yandex.ru; Tikunov, D.; Orlenko, S.; Skvortsov, V.; Stepanenko, V. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249020 (Russian Federation); Hoshi, M. [Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan)

    2007-07-15

    By Monte-Carlo simulation of ionizing particles transport, for a realistic mathematical phantom of a man supplemented by a dental region, absorbed doses in teeth enamel and whole body doses are calculated for cases of internal irradiation by {sup 137}Cs and {sup 134}Cs isotopes incorporated in the human body resulted from staying in radioactive contaminated territory. It is shown that dose in enamel constitutes (40{+-}4)% and (59{+-}6)% of whole body dose resulted from the decay of {sup 137}Cs and {sup 134}Cs isotopes, respectively. The results of calculations may be used for conversion of absorbed dose in enamel obtained by the tooth enamel EPR spectroscopy method to whole body dose for dosimetric investigation of population of territories contaminated by the radioactive cesium, which is specific for the Chernobyl accident.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Belinato Walmir

    2014-03-01

    Full Text Available 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.

  7. Structural changes caused by radiation-induced reduction and radiolysis: the effect of X-ray absorbed dose in a fungal multicopper oxidase

    Energy Technology Data Exchange (ETDEWEB)

    De la Mora, Eugenio [Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210 (Mexico); Lovett, Janet E. [University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); University of Oxford, South Parks Road, Oxford OX1 3RE (United Kingdom); EaStCHEM School of Chemistry, Joseph Black Building, The King’s Buildings, Edinburgh EH9 3JJ, Scotland (United Kingdom); Blanford, Christopher F. [University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Manchester Interdisciplinary Biocentre, 131 Princess Street, Manchester M1 7DN (United Kingdom); Garman, Elspeth F. [University of Oxford, South Parks Road, Oxford OX1 3QU (United Kingdom); Valderrama, Brenda; Rudino-Pinera, Enrique, E-mail: rudino@ibt.unam.mx [Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210 (Mexico)

    2012-05-01

    Radiation-induced reduction, radiolysis of copper sites and the effect of pH value together with the concomitant geometrical distortions of the active centres were analysed in several fungal (C. gallica) laccase structures collected at cryotemperature. This study emphasizes the importance of careful interpretation when the crystallographic structure of a metalloprotein is described. 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{sub 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{sub 2} reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account.

  8. The biodistribution and dosimetry of {sup 117m}Sn DTPA with special emphasis on active marrow absorbed doses

    Energy Technology Data Exchange (ETDEWEB)

    Stubbs, J. [Radiation Dosimetry Systems of Oak Ridge Inc., Knoxville, TN (United States); Atkins, H. [Brookhaven National Lab., Upton, NY (United States)

    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.

  9. EURAMET.RI(I)-S7 comparison of alanine dosimetry systems for absorbed dose to water measurements in gamma- and x-radiation at radiotherapy levels

    Science.gov (United States)

    Garcia, Tristan; Anton, Mathias; Sharpe, Peter

    2012-01-01

    The National Physical Laboratory (NPL), the Physikalisch-Technische Bundesanstalt (PTB) and the Laboratoire National Henri Becquerel (LNE-LNHB) are involved in the European project 'External Beam Cancer Therapy', a project of the European Metrology Research Programme. Within this project, the electron paramagnetic resonance (EPR)/alanine dosimetric method has been chosen for performing measurements in small fields such as those used in IMRT (intensity modulated radiation therapy). In this context, these three National Metrology Institutes (NMI) wished to compare the result of their alanine dosimetric systems (detector, modus operandi etc) at radiotherapy dose levels to check their consistency. This EURAMET.RI(I)-S7 comparison has been performed with the support of the Bureau International des Poids et Mesures (BIPM) which collected and distributed the results as a neutral organization, to ensure the comparison was 'blind'. Irradiations have been made under reference conditions by each laboratory in a 60Co beam and in an accelerator beam (10 MV or 12 MV) in a water phantom of 30 cm × 30 cm × 30 cm in a square field of 10 cm × 10 cm at the reference depth. Irradiations have been performed at known values of absorbed dose to water (Dw) within 10% of nominal doses of 5 Gy and 10 Gy, i.e. between 4.5 Gy and 5.5 Gy and between 9 Gy and 11 Gy, respectively. Each participant read out their dosimeters and assessed the doses using their own protocol (calibration curve, positioning device etc) as this comparison aims at comparing the complete dosimetric process. The results demonstrate the effectiveness of the EPR/alanine dosimetry systems operated by National Metrology Institutes as a method of assuring therapy level doses with the accuracy required. The maximum deviation in the ratio of measured to applied dose is less than 1%. 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

  10. Absorbed doses profiles vs Synovia tissue depth for the Y-90 and P-32 used in radiosynoviortesis treatment; Perfiles de dosis absorbida vs profundidad de tejido sinovial para el Y-90 y el P-32 empleados en tratamiento de radiosinoviortesis

    Energy Technology Data Exchange (ETDEWEB)

    Torres B, M.B.; Ayra P, F.E. [Centro de Isotopos (Cuba); Garcia R, E. [Hospital General Docente Enrique Cabrera (Cuba); Cornejo D, N. [CPHR, (Cuba); Yoriyaz, H. [IPEN, (Brazil)]. e-mail: nestor@cphr.edu.cu

    2006-07-01

    The radiosynoviortesis treatment has been used during more of 40 years as an alternative to the chemical and surgical synovectomy to alleviate the pain and to reduce the inflammation in suffered patients of rheumatic arthropathies, haemophilic arthropathies and other articulation disorders. It consists on the injection of radioactive isotopes inside a synovial cavity. For to evaluate the dosimetry of the radiosynoviortesis treatment is of great interest to know the absorbed dose in the volume of the target (synovia). The precise calculation of the absorbed dose in the inflamed synovia it is difficult, for numerous reasons, since the same one will depend on the thickness of the synovial membrane, the size of the articular space, the structure of the synovial membrane, the distribution in the articulation, the nature of the articular liquid, etc. Also the presence of the bone and the articular cartilage, components also of the articulation, it even complicated more the calculations. The method used to evaluate the dosimetry in radioactive synovectomy is known as the Monte Carlo method. The objective of our work consists on estimating with the Monte Carlo code MCNP4B the absorbed dose of the Y-90 and the P-32 in the depth of the synovial tissue. The results are presented as absorbed dose for injected millicurie (Gy/mCi) versus depth of synovial tissue. The simulation one carries out keeping in mind several synovia areas, of 50 cm{sup 2} to 250 cm{sup 2} keeping in mind three states of progression of the illness. Those obtained values of absorbed dose using the MCNP4B code will allow to introduce in our country an optimized method of dose prescription to the patient, to treat the rheumatic arthritis in medium and big articulations using the Y-90 and the P-32, eliminating the fixed doses and fixed radionuclides for each articulation like it happens in many clinics of Europe, as well as the empiric doses. (Author)

  11. Fishes of water bodies within the Ukrainian part of the Chernobyl exclusion zone: current levels of radioactive contamination and absorbed dose rate

    Energy Technology Data Exchange (ETDEWEB)

    Kaglyan, Alexander Ye.; Gudkov, Dmitri I. [Institute of Hydrobiology of the NAS of Ukraine, Geroyiv Stalingrada Ave. 12, UA- 04210, Kyiv (Ukraine)

    2014-07-01

    The results of studies of radioactive contamination of ichthyofauna of water bodies of the Chernobyl exclusion zone (ChEZ) during 2012-2013 are presented. The fish sampled from water bodies with different hydrological mode was used: (1) stagnant lakes (Vershyna, Glyboke, Azbuchyn, Daleke); (2) reservoir with slow water exchange (cooling pond of the Chernobyl NPP); (3) conditionally stagnant water bodies (separated from the main riverbed of the Pripyat River - Yanovsky and Novoshepelichesky Crawls and part of the Krasnensky former river bed); (4) semi-flowing water body (Krasnensky former river bed located outside of the dammed territory); (5) open crawls of the Pripyat river ('Schepochka' and Chernobylsky) and (6) waterway (riverbed sites of the Pripyat River). The highest levels of radionuclide concentrations were determined in fish of the stagnant water objects - 937-25907 Bq/kg (w.w.) of {sup 137}Cs and 1845-101220 Bq/kg of {sup 90}Sr. In fish of cooling pond the concentration of {sup 137}Cs registered in range 750-4200 and {sup 90}Sr - 41-512 Bq/kg. In ichthyofauna of water bodies which concern to the third group, specific activity of {sup 137}Cs and {sup 90}Sr fluctuated accordingly within range of 520-3385 and 722-6210, and in a semi-flowing reservoir - 573-2948 and 97-4484 Bq/kg. The concentrations of {sup 137}Cs in fish of the fifth and sixth groups were accordingly 25-159 and 11-224 as well as {sup 90}Sr - 36-174 and 3-14 Bq/kg. The ratio of specific activity of {sup 90}Sr/{sup 137}Cs for pray fish from all studied groups of water bodies, except the second and the sixth ones, was in range 1.5-39.7. Thus intensity of water exchange is one of the defining factors, influencing on level of radionuclide specific activity in fish, especially {sup 90}Sr - the higher the flow age, the lower the level of radioactive contamination of fish inhabiting it. Calculation of the absorbed dose rate has shown that highest radiation dose was in fish inhabiting lake

  12. Comparison between absorbed dose to water standards established by water calorimetry at the LNE-LNHB and by application of international air-kerma based protocols for kilovoltage medium energy x-rays.

    Science.gov (United States)

    Perichon, N; Rapp, B; Denoziere, M; Daures, J; Ostrowsky, A; Bordy, J-M

    2013-05-07

    Nowadays, the absorbed dose to water for kilovoltage x-ray beams is determined from standards in terms of air-kerma by application of international dosimetry protocols. New standards in terms of absorbed dose to water has just been established for these beams at the LNE-LNHB, using water calorimetry, at a depth of 2 cm in water in accordance with protocols. The aim of this study is to compare these new standards in terms of absorbed dose to water, to the dose values calculated from the application of four international protocols based on air-kerma standards (IAEA TRS-277, AAPM TG-61, IPEMB and NCS-10). The acceleration potentials of the six beams studied are between 80 and 300 kV with half-value layers between 3.01 mm of aluminum and 3.40 mm of copper. A difference between the two methods smaller than 2.1% was reported. The standard uncertainty of water calorimetry being below 0.8%, and the one associated with the values from protocols being around 2.5%, the results are in good agreement. The calibration coefficients of some ionization chambers in terms of absorbed dose to water, established by application of calorimetry and air-kerma based dosimetry protocols, were also compared. The best agreement with the calibration coefficients established by water calorimetry was found for those established with the AAPM TG-61 protocol.

  13. On the implementation of new versions of the algorithms of calculation of dose absorbed in radiotherapy external; Sobre la implementacion de nuevas versiones de los algoritmos de calculo de dosis absorbida en radioterapia externa

    Energy Technology Data Exchange (ETDEWEB)

    Latorre-Musoll, A.; Carrasco de Fez, P.; Lizondo Gisbert, M.; Jordi-Ollero, O.; Jornet Sala, N.; Eudaldo Puell, T.; Ruiz Martinez, A.; Ribas Morales, M.

    2015-07-01

    The changes of version of the algorithms of calculation of dose absorbed in radiotherapy external should implement in a time reduced due to the pressure care. A set reduced of checks could pass by high discrepancies significant between the stones and the measures experimental, as illustrate in this work. (Author)

  14. APMP supplementary comparison report of absorbed dose rate in tissue for beta radiation (BIPM KCDB: APMP.RI(I)-S2)

    Science.gov (United States)

    Kato, M.; Kurosawa, T.; Saito, N.; Kadni, T. B.; Kim, I. J.; Kim, B. C.; Yi, C.-Y.; Pungkun, V.; Chu, C.-H.

    2017-01-01

    The supplementary comparison of absorbed dose rate in tissue for beta radiation (APMP.RI(I)-S2) was performed with five national metrology institutes in 2013 and 2014. Two commercial thin window ionization chambers were used as transfer instruments and circulated among the participants. Two of the NMIs measured the calibration coefficients of the chambers in reference fields produced from Pm-147, Kr-85 and Sr-90/Y-90, while the other three measured those only in Sr-90/Y-90 beta-particle field. The degree of equivalence for the participants was determined and this comparison verifies the calibration capabilities of the participating laboratories. In addition, most of the results of this comparison are consistent with another international comparison (EUROMET.RI(I)-S2) reported before this work. 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).

  15. Análise da distribuição espacial de dose absorvida em próton terapia ocular Spatial distribution analysis of absorbed dose in ocular proton radiation therapy

    Directory of Open Access Journals (Sweden)

    Marília Tavares Christóvão

    2010-08-01

    of proton therapy were performed based on preexisting facilities. RESULTS: Simulation data were integrated into SISCODES on the eye's model generating spatial dose distributions. Dose depth profiles reproducing the pure and modulated Bragg peaks are presented. Relevant aspects of proton beam radiotherapy planning are considered such as material absorber, modulation, collimator dimensions, incident proton energy and isodose generation. CONCLUSION: The conclusion is that proton therapy when properly modulated and directed can reproduce the ideal conditions for the dose deposition in the treatment of ocular tumors.

  16. Characterization of an absorbed dose standard in water through ionometric methods; Caracterizacion de un patron de dosis absorbida en agua mediante metodos ionometricos

    Energy Technology Data Exchange (ETDEWEB)

    Vargas V, M.X

    2003-07-01

    In this work the unit of absorbed dose at the Secondary Standard Dosimetry Laboratory (SSDL) of Mexico, is characterized by means of the development of a primary standard of absorbed dose to water, D{sub agua}. The main purpose is to diminish the uncertainty in the service of dosimetric calibration of ionization chambers (employed in radiotherapy of extemal beams) that offers this laboratory. This thesis is composed of seven chapters: In Chapter 1 the position and justification of the problem is described, as well as the general and specific objectives. In Chapter 2, a presentation of the main quantities and units used in dosimetry is made, in accordance with the recommendations of the International Commission on Radiation Units and Measurements (ICRU) that establish the necessity to have a coherent system with the international system of units and dosimetric quantities. The concepts of equilibrium and transient equilibrium of charged particles (TCPE) are also presented, which are used later in the quantitative determination of D{sub agua}. Finally, since the proposed standard of D{sub agua} is of ionometric type, an explanation of the Bragg-Gray and Spencer-Attix cavity theories is made. These theories are the foundation of this type of standards. On the other hand, to guarantee the complete validity of the conditions demanded by these theories it is necessary to introduce correction factors. These factors are determined in Chapters 5 and 6. Since for the calculation of the correction factors Monte Carlo (MC) method is used in an important way, in Chapter 3 the fundamental concepts of this method are presented; in particular the principles of the code MCNP4C [Briesmeister 2000] are detailed, making emphasis on the basis of electron transport and variance reduction techniques used in this thesis. Because a phenomenological approach is carried out in the development of the standard of D{sub agua}, in Chapter 4 the characteristics of the Picker C/9 unit, the

  17. A water calorimeter for on-site absorbed dose to water calibrations in 60Co and MV-photon beams including MRI incorporated treatment equipment

    Science.gov (United States)

    de Prez, Leon; de Pooter, Jacco; Jansen, Bartel; Aalbers, Tony

    2016-07-01

    In reference dosimetry the aim is to establish the absorbed dose to water, D w, under reference conditions. However, existing dosimetry protocols are not always applicable for rapidly emerging new treatment modalities. For primary standard dosimetry laboratories it is generally not feasible to acquire such modalities. Therefore it is strongly desired that D w measurements with primary standards can be performed on-site in clinical beams for the new treatment modalities in order to characterize and calibrate detectors. To serve this need, VSL has developed a new transportable water calorimeter serving as a primary D w standard for 60Co and MV-photons including MRI incorporated treatment equipment. Special attention was paid to its operation in different beam geometries and beam modalities including the application in magnetic fields. The new calorimeter was validated in the VSL 60Co beam and on-site in clinical MV-photon beams. Excellent agreement of 0.1% was achieved with previous 60Co field calibrations, i.e. well within the uncertainty of the previous calorimeter, and with measurements performed in horizontal and vertical MV-photon beams. k Q factors, determined for two PTW 30013 ionization chambers, agreed very well with available literature data. The relative combined standard uncertainty (k  =  1) for D w measurements in 60Co and MV-photons is 0.37%. Calibrations are carried out with a standard uncertainty of 0.42% and k Q -factors are determined with a relative standard uncertainty of 0.40%.

  18. 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

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, N; Kita, A; Yoshioka, C; Sasamoto, K; Nishimoto, Y; Adachi, T [University of Fukui Hospital, Eiheiji, Fukui (Japan); Oguchi, H [Nagoya University Graduate School of Medicine, Nagoya, Aichi (Japan); Shioura, H; Kimura, H [University of Fukui, Eiheiji, Fukui (Japan)

    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.

  19. Evaluation of absorbed effective dose and treatment conditions for a brain tumor outside of the head phantom center in treatment by Boron Neutron Capture Therapy Using Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Samira Mirzaiee

    2016-04-01

    (including 252Cf source, moderator, refelector and neutron and photon filters was simulated. A spherical-shaped tumor was considered outside of the phantom center. The head phantom consists of three parts of the skin, skull and brain. The simulation was done by the MCNPX 2.6.0 computational code. In this simulation, the tumor with a radius of 1.5 cm at a depth of 2 cm inside the brain was considered. Results: Tumor treatment was investigated with different boron concentrations in the head phantom. The maximum dose is approximately 0.055 Sv/hr, and is related to the conditions that Boron is not absorbed in healthy tissue. The absorbed dose amount of the epithermal neutrons, under the conditions that Boron is not absorbed in healthy tissue, at the entrance of the skull and in brain tissue extremily drops, and gradually decreases. Conclusion: The calculations showed when a patient receives radiation about 5 minutes, the received dose equals approximately 4.6 mSv.Under these treatment conditions, the whole body equivalent dose  does not exceed 5 mSv per year.

  20. Characterization of an absorbed dose standard in water through ionometric methods; Caracterizacion de un patron de dosis absorbida en agua mediante metodos ionometricos

    Energy Technology Data Exchange (ETDEWEB)

    Vargas V, M.X

    2003-07-01

    In this work the unit of absorbed dose at the Secondary Standard Dosimetry Laboratory (SSDL) of Mexico, is characterized by means of the development of a primary standard of absorbed dose to water, D{sub agua}. The main purpose is to diminish the uncertainty in the service of dosimetric calibration of ionization chambers (employed in radiotherapy of extemal beams) that offers this laboratory. This thesis is composed of seven chapters: In Chapter 1 the position and justification of the problem is described, as well as the general and specific objectives. In Chapter 2, a presentation of the main quantities and units used in dosimetry is made, in accordance with the recommendations of the International Commission on Radiation Units and Measurements (ICRU) that establish the necessity to have a coherent system with the international system of units and dosimetric quantities. The concepts of equilibrium and transient equilibrium of charged particles (TCPE) are also presented, which are used later in the quantitative determination of D{sub agua}. Finally, since the proposed standard of D{sub agua} is of ionometric type, an explanation of the Bragg-Gray and Spencer-Attix cavity theories is made. These theories are the foundation of this type of standards. On the other hand, to guarantee the complete validity of the conditions demanded by these theories it is necessary to introduce correction factors. These factors are determined in Chapters 5 and 6. Since for the calculation of the correction factors Monte Carlo (MC) method is used in an important way, in Chapter 3 the fundamental concepts of this method are presented; in particular the principles of the code MCNP4C [Briesmeister 2000] are detailed, making emphasis on the basis of electron transport and variance reduction techniques used in this thesis. Because a phenomenological approach is carried out in the development of the standard of D{sub agua}, in Chapter 4 the characteristics of the Picker C/9 unit, the

  1. Comparison in the determination of absorbed dose by biological and physical methods to patients in treatment of cardiac intervention; Comparacion en la determinacion de dosis absorbida por metodos biologicos y fisicos a pacientes en tratamiento de intervencionismo cardiaco

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero C, C.; Arceo M, C., E-mail: citlali.guerrero@inin.gob.mx [ININ, Departamento de Biologia, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    The use of less invasive procedures, lower risk and quick recovery as cardiac intervention have proven to be an efficient alternative to reestablish the correct bloodstream of the patient. In this case the patient is subjected to values of absorbed dose above to which is subjected in a study with X-rays for medical diagnosis, and this can cause radiation injuries to the skin. The target organ, in this case can be exposed to doses of 2 Gy above. Different methods to estimate the dose were use, physical by Radiochromic film, as biological by dicentric analysis. Both methods provided additional information demonstrating thus the risk in the target organ and the patient. The most reliable biological indicator of exposure to ionizing radiation is the study of chromosomal aberrations, specifically dicentric in human lymphocytes. This test allowed establishing the exposure dose depending of the damage. (Author)

  2. Regression models in the determination of the absorbed dose with extrapolation chamber for ophthalmological applicators; Modelos de regresion en la determinacion de la dosis absorbida con camara de extrapolacion para aplicadores oftalmologicos

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, J.T.; Morales P, R

    1992-06-15

    The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, ({sup 90} Sr/{sup 90} Y, 1850 MBq) using an extrapolation chamber of variable electrodes; when estimating the slope of the extrapolation curve using a simple lineal regression model is observed that the dose values are underestimated from 17.7 percent up to a 20.4 percent in relation to the estimate of this dose by means of a regression model polynomial two grade, at the same time are observed an improvement in the standard error for the quadratic model until in 50%. Finally the global uncertainty of the dose is presented, taking into account the reproducibility of the experimental arrangement. As conclusion it can infers that in experimental arrangements where the source is to contact with the extrapolation chamber, it was recommended to substitute the lineal regression model by the quadratic regression model, in the determination of the slope of the extrapolation curve, for more exact and accurate measurements of the absorbed dose. (Author)

  3. 电离法校准低能质子剂量技术%Calibration Method of Absorbed Dose for Low Energy Proton Using Ionization Method

    Institute of Scientific and Technical Information of China (English)

    陈义珍; 林敏; 陈克胜; 徐利军; 夏文; 崔莹; 肖振红

    2012-01-01

    本工作建立1套电离室绝对剂量测量系统,对自制石墨电离室性能进行研究,实验结果表明自制电离室系统满足标准电离室的要求.设计了1套基于同向测量的透射电离室,用于在线监测束流变化,为剂量测量的准确性提供了依据,解决了替代法校准时束流波动对测量结果造成较大不确定度的问题.对已建立的电离室测量低能质子吸收剂量绝对测量系统进行不确定度评估,合成标准不确定度约4%.最后,以自行研制的质子剂量测量系统(电离室系统、透射电离室系统)在HI-13串列加速器上开展了对丙氨酸剂量计校准技术的研究,获得了不同能量质子辐照下的RE值.%A set of dosimetry system with graphite ionization chamber for low energy proton beams was set up. The characteristics of self-developed graphite ionization chamber were studied. The results show that the self-developed graphite ionization chamber meets the requirement of standard ionization chamber. Transmission ionization chamber was designed and used to monitor the change of proton beams online, which increased the accuracy of results when calibrating the other dosimetry systems. Absorbed dose of low energy proton was measured by using self-developed dosimetry system with ionization chamber, and the composed standard uncertainty is 4%. The calibration method of alanine dosimeter was researched in the HI-13 Tandem Accelerator, and the RE specific values were obtained for the different proton energy.

  4. Rastreabilidade das referências metrológicas em dose absorvida na água do Programa de Qualidade em Dosimetria Traceability of metrologic references of dose absorbed to water used in a Dosimetry Quality Assurance Program

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo de Almeida

    2005-06-01

    Full Text Available OBJETIVO: Este trabalho tem por objetivo apresentar a estrutura solidamente estabelecida de rastreabilidade dos padrões ionométricos e do sistema de medidas com dosímetros termoluminescentes, como parte da confiabilidade do Programa de Qualidade em Dosimetria (PQD, que visa a garantir o mais elevado nível de exatidão às suas medidas. MATERIAIS E MÉTODOS: A exemplo de outros programas, usaram-se dosímetros termoluminescentes (DTL 937 na forma de pó, colocados em uma cápsula de plástico, em "kits" específicos para cada aplicação, os quais foram enviados, por via postal, aos centros participantes. RESULTADOS: Os resultados da intercomparação realizada entre o Laboratório de Ciências Radiológicas da Universidade do Estado do Rio de Janeiro e o EQUAL-ESTRO para o feixe de raios gama de 60Co, expressos para (1sigma, e os resultados das medidas de dose absorvida, obtidos com as câmaras dp Programa EQUAL e as câmaras do PQD, apresentaram discordância menor que 0,5%. CONCLUSÃO: Dos resultados conclui-se que o PQD alcançou o nível desejado de confiabilidade, necessário à implementação do Programa.OBJECTIVE: To present the solidly established traceability structure for ionometric standards and for thermoluminescent dosimetry system that ensures reliability of the Dosimetry Quality Assurance Program and is aimed to certify the highest level of accuracy of the measurements. MATERIALS AND METHODS: Thermoluminescent powder dosimeters (DTL 937 placed into plastic capsules and packed in specific kits for each intended application were mailed to the participant centers. RESULTS: The results of the intercomparisons performed between "Laboratório de Ciências Radiológicas da Universidade do Estado do Rio de Janeiro" and EQUAL-ESTRO for the beam of 60Co gamma rays, expressed for (1sigma, and the results of the dose absorbed measurements obtained with the chambers of the Program EQUAL and the chambers of the Dosimetry Quality Assurance

  5. Measuring the absorbed dose in critical organs during low rate dose brachytherapy with {sup 137} Cs using thermoluminescent dosemeters; Medicion de la dosis absorbida en organos criticos durante braquiterapia de baja tasa de dosis con {sup 137} Cs usando dosimetros termoluminiscentes

    Energy Technology Data Exchange (ETDEWEB)

    Torres, A. [UAEM, Fac. de Medicina, 50180 Toluca, Estado de Mexico (Mexico); Gonzalez, P.R. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Furetta, C.; Azorin, J. [UAM-I, 09340 Mexico D.F. (Mexico); Andres, U.; Mendez, G. [Centro Estatal de Cancerologia de Tabasco, A. Gregorio Mendez No. 2838, Col. Atasta, 86100 Villahermosa, Tabasco (Mexico)

    2003-07-01

    Intracavitary Brachytherapy is one of the most used methods for the treatment of the cervical-uterine cancer. This treatment consists in the insertion of low rate dose {sup 137}Cs sources into the patient. The most used system for the treatment dose planning is that of Manchester. This planning is based on sources, which are considered fixed during the treatment. However, the experience has shown that, during the treatment, the sources could be displaced from its initial position, changing the dose from that previously prescribed. For this reason, it is necessary to make measurements of the absorbed dose to the surrounding organs (mainly bladder and rectum). This paper presents the results of measuring the absorbed dose using home-made LiF: Mg, Cu, P + Ptfe thermoluminescent dosimeters (TLD). Measurements were carried out in-vivo during 20 minutes at the beginning and at the end of the treatments. Results showed that the absorbed dose to the critical organs vary significantly due to the movement of the patient during the treatment. (Author)

  6. Estimation of absorbed and effective dose in {sup 18}F-FDG em PET- CT exams for diagnosis of lung cancer; Estimativa de dose absorvida e efetiva em exames de {sup 18}F-FDG em PET- CT para diagnostico de cancer de pulmao

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Guilherme Neto de Pinho; Santana, Priscila do Carmo, E-mail: guinpc1@ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem; Oliveira, Paulo Marcio Campos de; Reis, Lucas Paixao dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-04-15

    This paper presents an evaluation of tissues and organs absorbed doses as well as the effective dose resulting from PET-CT scans performed with {sup 18}F-FDG radiopharmaceutical for lung cancer diagnosis in whole body scans. The ICRP-106 biokinetic model was used to estimate the absorbed and effective doses from the radiopharmaceutical for both male and female patient according to the characteristics of anthropomorphic Alderson Rando® simulators. Computer Tomography doses were evaluated using thermoluminescent detectors inserted in the same anthropomorphic simulators. Optimization protocols for image acquisition and the use of automatic exposure control were used in order to reduce patient doses, taking into account the equipment model and its system. The effective dose in female patients was 5.8 mSv. The effective dose in male patients was 8.4 mSv. The dose values estimated for the {sup 18}F-FDG PET-CT scan are below the values described in the literature. This is because the CT was not used for diagnostic but for morphological mapping. (author)

  7. Data on biodistribution and radiation absorbed dose profile of a novel 64Cu-labeled high affinity cell-specific peptide for positron emission tomography imaging of tumor vasculature

    Directory of Open Access Journals (Sweden)

    Joseph R. Merrill

    2016-06-01

    Full Text Available New peptide-based diagnostic and therapeutic approaches hold promise for highly selective targeting of cancer leading to more precise and effective diagnostic and therapeutic modalities. An important feature of these approaches is to reach the tumor tissue while limiting or minimizing the dose to normal organs. In this context, efforts to design and engineer materials with optimal in vivo targeting and clearance properties are important. This Data In Brief article reports on biodistribution and radiation absorbed dose profile of a novel high affinity radiopeptide specific for bone marrow-derived tumor vasculature. Background information on the design, preparation, and in vivo characterization of this peptide-based targeted radiodiagnostic is described in the article “Synthesis and comparative evaluation of novel 64Cu-labeled high affinity cell-specific peptides for positron emission tomography of tumor vasculature” (Merrill et al., 2016 [1]. Here we report biodistribution measurements in mice and calculate the radiation absorbed doses to normal organs using a modified Medical Internal Radiation Dosimetry (MIRD methodology that accounts for physical and geometric factors and cross-organ beta doses.

  8. Dose absorbed in adults and children thyroid due to the I{sup 123} using the dosimetry MIRD and Marinelli; Dosis absorbida en tiroides de adultos y ninos debido al I{sup 123} utilizando las dosimetrias MIRD y Marinelli

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, M.; Castillo, C.; Cabrera, C.; Sarachaga, R.; Castaneda, J. [Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Ciudad Universitaria, Trujillo (Peru); Diaz, E., E-mail: marvva@hotmail.com [Universidade Federal do Rio Grande do Sul, Av. Paulo Gamma 110, Bairro Farropilhas, Porto Alegre, RS 90040-060 (Brazil)

    2014-08-15

    Using the dosimetry MIRD, and representation Cristy-Eckerman in the thyroid gland and organs of their bio-kinetics when I{sup 123} (Iodine) is used, the study demonstrates that the absorbed dose by the gland of an adult, children, and newly born, is their auto-dose, independent of the compartments number of their bio-kinetics. The dosimetric contributions of the organs of their bio-kinetics are insignificant. Their results are not significantly different to those obtained by the formalism MARINELLI (auto-dose) when it uses a sphere like glandular representation. In consequence, the kinetic model corresponding to the glandular representation decreases to a compartment, where the gland can also be represented like a sphere. (Author)

  9. Sound Absorbers

    Science.gov (United States)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  10. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD; Cartas de control e incertidumbres de los patrones de kerma en aire, dosis absorbida en agua y dosis absorbida en aire del LSCD

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, M.T.; Tovar M, V.M.; Cejudo A, J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2005-12-15

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air {kappa}{sub {alpha}}{sub {center_dot}}, dose speed absorbed in water D{alpha}{sub {center_dot}}, and speed absorbed dose in air D{alpha}{sub {center_dot}}, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups {sigma}{sub {omega}} and that of long term by means of the standard deviation among groups {sigma}{sub {beta}}, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) {kappa}{sub {alpha}}{sub {center_dot}}, in radiation field of {sup 60}Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) D{alpha}),en radiation field of {sup 60}Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of {sup 90}Sr-{sup 90}Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases {sigma}{sub {beta}}, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of {sigma}{sub {beta}}. For example with sizes of subgroup {eta}{sub {approx}} 30 data, or with a number of subgroups {kappa}{sub {>=}}. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the

  11. Tumoral fibrosis effect on the radiation absorbed dose of {sup 177}Lu-Tyr{sup 3}-octreotate-gold nanoparticles and {sup 177}Lu-Tyr{sup 3}-octreotate radiopharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Zambrano R, O. D.

    2015-07-01

    In this work was comparatively evaluated the effect of tumoral fibrosis in the radiation absorbed dose of the radiopharmaceutical {sup 177}Lu-Tyr{sup 3}-octreotate with and without gold nanoparticles. For this, was used an experimental array of tumoral fibrosis and computer models based on Monte Carlo calculations to simulate tumoral micro environments without fibrosis and with fibrosis. The computer simulation code Penelope (Penetration Energy Loss of Positron and Electrons) and MCNP (Monte Carlo N-particle Transport Code System) which are based on the Monte Carlo methodology were used to create the computer models for the simulation of the transport of particles (emitted by {sup 177}Lu) in the micro environments (without fibrosis and with fibrosis) with the purpose of calculating the radiation absorbed dose in the interstitial space and in the nucleus of cancer cells. The first computational model consisted of multiple concentric spheres (as onion shells) with the radioactive source homogeneously distributed in the shell between 5 and 10 μm in diameter which represents the internalization of the radioactive source into the cell cytoplasm as it occurs in target specific radiotherapy. The concentric spheres were useful to calculate the radiation absorbed dose in depth in the models without fibrosis and with fibrosis. Furthermore, there were constructed other computer models using two different codes that simulate the transport of radiation (Penelope and MCNP). These models consist of seven spheres that represent cancer cells (HeLa cells) of 10 μm in diameter and each one of them contain another smaller sphere in the center that represents the cell nucleus. A comparison was done of the radiation absorbed dose in the nucleus of the cells, calculated with both codes, Penelope and MCNP. The radioactive source ({sup 177}Lu) used for the simulations was given to the codes by means of a convoluted spectrum of the most important beta particles (high percentage emission

  12. Determination of absorbed dose in water at the reference point D(r{sub 0},{theta}{sub 0}) for an {sup 192}Ir HDR brachytherapy source using a Fricke system

    Energy Technology Data Exchange (ETDEWEB)

    Austerlitz, C.; Mota, H. C.; Sempau, J.; Benhabib, S. M.; Campos, D.; Allison, R.; Almeida, C. E. de; Zhu, D.; Sibata, C. H. [Department of Radiation Oncology, East Carolina University, Greenville, North Carolina 27834 (United States); Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya, 08028 Barcelona (Spain); Department of Radiation Oncology, East Carolina University, Greenville, North Carolina 27834 (United States); Laboratorio de Cie circumflex ncias Radiologicas, Universidade do Estado do Rio de Janeiro, 20550 Rio de Janeiro (Brazil); Department of Radiation Oncology, East Carolina University, Greenville, North Carolina 27834 (United States)

    2008-12-15

    A ring-shaped Fricke device was developed to measure the absolute dose on the transverse bisector of a {sup 192}Ir high dose rate (HDR) source at 1 cm from its center in water, D(r{sub 0},{theta}{sub 0}). It consists of a polymethylmethacrylate (PMMA) rod (axial axis) with a cylindrical cavity at its center to insert the {sup 192}Ir 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(r{sub 0},{theta}{sub 0}). Irradiations were performed with a Nucletron microselectron HDR unit loaded with an {sup 192}Ir 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 {sup 192}Ir 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(r{sub 0},{theta}{sub 0}) by 2.0%. Applying the corresponding correction factor, the D(r{sub 0},{theta}{sub 0}) 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

  13. Spectra and absorbed dose by photo-neutrons in a solid water mannequin exposed to a Linac of 15 MV; Espectros y dosis absorbida por fotoneutrones en un maniqui de agua solida expuesta a una Linac de 15 MV

    Energy Technology Data Exchange (ETDEWEB)

    Benites R, J. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calz. de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Velazquez F, J., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado en Ciencias Biologico Agropecuarias, Carretera Tepic-Compostela Km 9, 63780 Jalisco-Nayarit (Mexico)

    2012-10-15

    Using Monte Carlo methods was modeled a solid water mannequin; according to the ICRU 44 (1989), Tissue substitutes in radiation dosimetry and measurements, of the International Commission on Radiation Units and Measurements; Report 44. This material Wt 1 is made of H (8.1%), C (67.2%), N (2.4%), O (19.9%), Cl (0.1%), Ca (2.3%) and its density is of 1.02 gr/cm{sup 3}. The mannequin was put instead of the patient, inside the treatment room and the spectra and absorbed dose were determined by photo-neutrons exposed to a Linac of 15 MV. (Author)

  14. Three-dimensional assessment of the effects of high-density embolization material on the absorbed dose in the target for Gamma Knife radiosurgery of arteriovenous malformations.

    Science.gov (United States)

    Watanabe, Yoichi; Sandhu, Divyajot; Warmington, Leighton; Moen, Sean; Tummala, Ramachandra

    2016-12-01

    OBJECTIVE Arteriovenous malformation (AVM) is an intracranial vascular disorder. Gamma Knife radiosurgery (GKRS) is used in conjunction with intraarterial embolization to eradicate the nidus of AVMs. Clinical results indicate that patients with prior embolization tend to gain less benefit from GKRS. The authors hypothesized that this was partly caused by dosimetric deficiency. The actual dose delivered to the target may be smaller than the intended dose because of increased photon attenuation by high-density embolic materials. The authors performed a phantom-based study to quantitatively evaluate the 3D dosimetric effect of embolic material on GKRS. METHODS A 16-cm-diameter and 12-cm-long cylindrical phantom with a 16-cm-diameter hemispherical dome was printed by a 3D printer. The phantom was filled with radiologically tissue-equivalent polymer gel. To simulate AVM treatment with embolization, phantoms contained Onyx 18. The material was injected into an AVM model, which was suspended in the polymer gel. The phantom was attached to a Leksell frame by standard GK fixation method, using aluminum screws, for imaging. The phantom was scanned by a Phillips CT scanner with the standard axial-scanning protocol (120 kV and 1.5-mm slice thickness). CT-based treatment planning was performed with the GammaPlan treatment planning system (version 10.1.1). The plan was created to cover a fictitious AVM target volume near the embolization areas with eleven 8-mm shots and a prescription dose of 20 Gy to 50% isodose level. Dose distributions were computed using both tissue maximum ratio (TMR) 10 and convolution dose-calculation algorithms. These two 3D dose distributions were compared using an in-house program. Additionally, the same analysis method was applied to evaluate the dosimetric effects for 2 patients previously treated by GKRS. RESULTS The phantom-based analyses showed that the mean dose difference between TMR 10 and convolution doses of the AVM target was no larger than

  15. Investigation of conformal and intensity-modulated radiation therapy techniques to determine the absorbed fetal dose in pregnant patients with breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Öğretici, Akın, E-mail: akinogretici@gmail.com; Akbaş, Uğur; Köksal, Canan; Bilge, Hatice

    2016-07-01

    The aim of this research was to investigate the fetal doses of pregnant patients undergoing conformal radiotherapy or intensity-modulated radiation therapy (IMRT) for breast cancers. An Alderson Rando phantom was chosen to simulate a pregnant patient with breast cancer who is receiving radiation therapy. This phantom was irradiated using the Varian Clinac DBX 600 system (Varian Medical System, Palo Alto, CA) linear accelerator, according to the standard treatment plans of both three-dimensional conformal radiation therapy (3-D CRT) and IMRT techniques. Thermoluminescent dosimeters were used to measure the irradiated phantom's virtually designated uterus area. Thermoluminescent dosimeter measurements (in the phantom) revealed that the mean cumulative fetal dose for 3-D CRT is 1.39 cGy and for IMRT it is 8.48 cGy, for a pregnant breast cancer woman who received radiation treatment of 50 Gy. The fetal dose was confirmed to increase by 70% for 3-D CRT and 40% for IMRT, if it is closer to the irradiated field by 5 cm. The mean fetal dose from 3-D CRT is 1.39 cGy and IMRT is 8.48 cGy, consistent with theoretic calculations. The IMRT technique causes the fetal dose to be 5 times more than that of 3-D CRT. Theoretic knowledge concerning the increase in the peripheral doses as the measurements approached the beam was also practically proven.

  16. Point absorbed dose verification for volumetric modulated arc therapy plans. A comparative study between ionization microchamber and chamber array; Verificacion de dosis absorbida en un punto para planes de arcoterapia volumetrica modulada. Estudio comparativo entre microcamara de ionizacion y matriz de camaras

    Energy Technology Data Exchange (ETDEWEB)

    Caudepon Moreno, F.; Pizarro Trigo, F.; Sanchez Jimenez, J.; Nunez Martinez, L.; Morillas Ruiz, J.; Palomo Llinares, R.

    2016-10-01

    According to the international recommendations a quality control must be made for IMRT treatments before these can be delivered. These recommendations are applied to volumetric modulated arc therapy treatments in our Department. As a part of the verifications chain, measurements of absorbed dose in a phantom point and in the phantom volume are made for a specific patient with ionization chamber and ionization chambers array, respectively. The aim of this issue is to compare measurements of absorbed dose between these two kinds of detectors. The predictions of absorbed dose from Treatment Planning System are taken as the reference one. The differences among these measurements and the reference are calculated for 105 specific patients. A statistical analysis shows that the measurements of absorbed dose with chamber and array are strongly correlated. This result allows us to eliminate from our verifications chain the measurements of absorbed dose in a phantom point with ionization chamber because these ones are included in measurements of absorbed dose in the volume with a very small statistic risk. As a result, much time can be saved in the verifications process without any lack of quality. (Author)

  17. Evaluation of the absorbed dose to the kidneys due to Tc{sup 99m} (DTPA) / Tc{sup 99m} (Mag3) and Tc{sup 99m} (Dmsa); Evaluacion de la dosis absorbida en los rinones debido al Tc{sup 99m} (DTPA) / Tc{sup 99m} (MAG3) y Tc{sup 99m} (DMSA)

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez A, M.; Murillo C, F.; Castillo D, C.; Rocha J, J.; Sifuentes D, Y.; Sanchez S, P. [Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Trujillo (Peru); Idrogo C, J.; Marquez P, F., E-mail: marvva@hotmail.com [Instituto Nacional de Enfermedades Neoplasicas, Av. Angamos 2520, Lima (Peru)

    2015-10-15

    The absorbed dose in the kidneys of adult patients has been assessed using the biokinetics of radiopharmaceuticals containing Tc{sup 99m} (DTPA) / Tc{sup 99m} (Mag3) or Tc{sup 99m} (Dmsa).The absorbed dose was calculated using the formalism MIRD and the Cristy-Eckerman representation for the kidneys. The absorbed dose to the kidneys due to Tc{sup 99m} (DTPA) / Tc{sup 99m} (Mag3), are given by 0.00466 mGy.MBq{sup -1} / 0.00339 mGy.MBq{sup -1}. Approximately 21.2% of the absorbed dose is due to the bladder (content) and the remaining tissue, included in biokinetics of Tc{sup 99m} (DTPA) / Tc{sup 99m} (Mag3). The absorbed dose to the kidneys due to Tc{sup 99m} (Dmsa) is 0.17881 mGy.MBq{sup -1}. Here, 1.7% of the absorbed dose is due to the bladder, spleen, liver and the remaining tissue, included in biokinetics of Tc{sup 99m} (Dmsa). (Author)

  18. Dosimetry for patients with differentiated thyroid cancer in therapy with {sup 131} (Nal) preceded by rec-hTSH and establishment of a correlation between absorbed dose and cytogenetic effects of radiation in humans

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, J.A.; Guimaraes, M.I.C.C.; Buchpiguel, C.A., E-mail: jgonzalez@usp.br [Universidade de Sao Paulo (CMN/InRad/HCFM/USP), SP (Brazil). Centro de Medicina Nuclear. Instituto de Radiologia. Hospital das Clinicas; Da Silva, M.A.; Okazaki, K.; Yoriyaz, H.; Bartolini, P., E-mail: masilva@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-11-01

    The objective of this study was to calculate the dosimetry for thyroid remnants and other organs of 22 patients with differentiated thyroid cancer and compare the dosimetric results with the genetic effects that may occur due the introduction of ionizing radiation in the human body. The patients were divided in two groups: group A included the patients that went through the interruption of the thyroid hormone reposition and group B included the ones that received the recombinant human Thyroid Stimulating Hormone (rec-hTSH). Blood samples were collected at predetermined intervals and analyzed with the conventional chromosomal aberrations technique. Patients collected their own urine during 24 hours after the administration of the radioiodine. For internal dosimetry calculations it is being used MlRD methodology and software MIRDOSE-3 and MlRDOSE-OLINDA. Preliminary results of the absorbed dose of 12 patients (6 from each group) show the normal pattern of this type of absorption in treatment of thyroid remnants ablation with a mean effective dose of 3 3.2 {+-} 6.4 mSv/MBq (group A) and 15.0 {+-} 4.5 mSv/MBq (group B). In the cytogenetic results for 5 patients (4 from group A and 1 from group B), the microscopic analysis showed the presence of various types of chromosomal aberrations. The dicentric chromosome was the most frequently found and is considered the most sensitive indicator of radiation damage. The correlation between the absorbed dose and the cytogenetic dosimetry appears to be in good agreement so far, since the doses are consistent with the genetic damage found. (author)

  19. Interlaboratory comparisons in kerma in the air measures and absorbed dose in water using {sup 6}0Co beams in radiotherapy; Comparacoes interlaboratoriais nas medidas de kerma no ar e dose absorvida na agua utilizando feixes de {sup 60}Co em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, Paulo Henrique Goncalves; Silva, Cosme Norival Mello da, E-mail: phrosado@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    In order to ensure that the measures of a quantity have high reliability and traceability interlaboratory comparisons are performed. The LNMRI has participated in several these interlaboratory comparisons. In the period 2000-2013 the LNMRI participated in 5 interlaboratory comparisons for measurement of kerma coefficients in the air and absorbed dose coefficients in the water. The results of interlaboratory comparisons indicate that the measures taken are appropriate to the LNMRI regarding the accuracy and precision measuring of these quantities.

  20. Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the LNE-LNHB, France and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Delaunay, F.; Donois, M.

    2013-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB), France and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in April 2013. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the LNE-LNHB and the BIPM standards for absorbed dose to water, is 0.9971 with a combined standard uncertainty of 3.9 × 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).

  1. Alanine-EPR dosimetry for measurements of ionizing radiation absorbed doses in the range 0.5-10 kGy

    CERN Document Server

    Peimel-Stuglik, Z

    2001-01-01

    The usefulness of two, easy accessible alanine dosimeters (ALANPOL from IChTJ and foil dosimeter from Gamma Service, Radeberg, Germany) to radiation dose measurement in the range of 0.5-10 kGy, were investigated. In both cases, the result of the test was positive. The foil dosemeter from Gamma Service is recommended for dose distribution measurements in fantoms or products, ALANPOL - for routine measurements. The EPR-alanine method based on the described dosimeters can be successfully used, among others, in the technology of radiation protection of food.

  2. Thyroid dose of I-131 absorbed by the internal organs of a pregnant woman; Dosis tiroidea de I-131 absorbida por los organos internos de una embarazada

    Energy Technology Data Exchange (ETDEWEB)

    Arcos P, A.; Manzanares A, E.; Vega C, H.R.; Leon, C.L. de [Cuerpo Academico de Radiobiologia de la Universidad Autonoma de Zacatecas (Mexico)]. e-mail: emanz_44@yahoo.com

    2007-07-01

    The use of nuclear techniques, for diagnosis or treatment, generates stress in the patient and its relatives. During the pregnancy some sufferings related with the thyroid gland can be presented. If the patient is pregnant, OEP or NOEP, the stress comes from the fear to that the product can it turns affected. The dose is calculated that the Iodine 131, captured by the thyroid of a woman with three months of pregnancy, it deposits in the brain, stomach, heart, kidneys, liver, lungs, ovaries, pancreas, thymus, spleen and in the uterus. The thymus is the organ that receives the biggest dose. (Author)

  3. Procedure and data evaluation to evaluate fetal absorbed dose in clinical radiated (X-ray) pregnant women; Descripcion del procedimiento y evaluacion de datos de estimacion de dosis absorbidas en feto para pacientes gestantes como consecuencia de la realizacion de pruebas radiodiagnosticas

    Energy Technology Data Exchange (ETDEWEB)

    Calama Santiago, J. A.; Gonzalez Ruiz, C.; Olivares Munoz, M. P.

    2006-07-01

    This paper details the procedure followed in our hospital to evaluate fetal absorbed dose in clinical radiated (X-ray) pregnant women. The description covers data request, calculations and report generation, and show the estimated dose since year 2000, comparing the results with the published data in the literature. (Author)

  4. Determination of absorbed dose distribution in water for COC ophthalmic applicator of {sup 106}Ru/{sup 106}Rh using Monte Carlo code-MCNPX; Determinacao da distribuicao de dose absorvida na agua para o aplicador oftalmico COC de {sup 106}Ru/{sup 106}Rh utilizando o codigo de Monte Carlo - MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Nilseia A.; Rosa, Luiz A. Ribeiro da, E-mail: nilseia@ird.gov.br, E-mail: lrosa@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ),Rio de Janeiro, RJ (Brazil); Braz, Delson, E-mail: delson@nuclear.ufrj.br [Coordenacao dos programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2014-07-01

    The COC ophthalmic applicators using beta radiation source of {sup 106}Ru/{sup 106}Rh are used in the treatment of intraocular tumors near the optic nerve. In this type of treatment is very important to know the dose distribution in order to provide the best possible delivery of prescribed dose to the tumor, preserves the optic nerve region extremely critical, that if damaged, can compromise the patient's visual acuity, and cause brain sequelae. These dose distributions are complex and doctors, who will have the responsibility on the therapy, only have the source calibration certificate provided by the manufacturer Eckert and Ziegler BEBIG GmbH. These certificates provide 10 absorbed dose values at water depth along the central axis applicator with the uncertainties of the order of 20% isodose and in a plane located 1 mm from the applicator surface. Thus, it is important to know with more detail and precision the dose distributions in water generated by such applicators. To this end, the Monte Carlo simulation was used using MCNPX code. Initially, was validated the simulation by comparing the obtained results to the central axis of the applicator with those provided by the certificate. The different percentages were lower than 5%, validating the used method. Lateral dose profile was calculated for 6 different depths in intervals of 1 mm and the dose rates in mGy.min{sup -1} for the same depths.

  5. The influence of saliva flow stimulation on the absorbed radiation dose to the salivary glands during radioiodine therapy of thyroid cancer using {sup 124}I PET(/CT) imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jentzen, Walter; Schmitz, Jochen; Freudenberg, Lutz; Eising, Ernst; Bockisch, Andreas; Stahl, Alexander [Universitaet Duisburg-Essen, Klinik fuer Nuklearmedizin, Essen (Germany); Balschuweit, Dorothee; Hilbel, Thomas [Fachhochschule Gelsenkirchen, Fachbereich Physikalische Technik, Gelsenkirchen (Germany)

    2010-12-15

    A serious side effect of high-activity radioiodine therapy in the treatment of differentiated thyroid cancer is radiogenic salivary gland damage. This damage may be diminished by lemon-juice-induced saliva flow immediately after {sup 131}I administration. The aim of this study was to assess the effect of chewing lemon slices on the absorbed (radiation) doses to the salivary glands. Ten patients received (pretherapy) {sup 124}I PET(/CT) dosimetry before their first radioiodine therapy. The patients underwent a series of six PET scans at 0.5, 1, 2, 4, 48 and {>=}96 h and one PET/CT scan at 24 h after administration of 27 MBq {sup 124}I. Blood samples were also collected at about 2, 4, 24, 48, and 96 h. Contrary to the standard radioiodine therapy protocol, the patients were not stimulated with lemon juice. Specifically, the patients chewed no lemon slices during the pretherapy procedure and neither ate food nor drank fluids until after completion of the last PET scan on the first day. Organ absorbed doses per administered {sup 131}I activity (ODpAs) as well as gland and blood uptake curves were determined and compared with published data from a control patient group, i.e. stimulated per the standard radioiodine therapy protocol. The calculations for both groups used the same methodology. A within-group comparison showed that the mean ODpA for the submandibular glands was not significantly different from that for the parotid glands. An intergroup comparison showed that the mean ODpA in the nonstimulation group averaged over both gland types was reduced by 28% compared to the mean ODpA in the stimulation group (p=0.01). Within each gland type, the mean ODpA reductions in the nonstimulation group were statistically significant for the parotid glands (p=0.03) but not for the submandibular glands (p=0.23). The observed ODpAs were higher in the stimulation group because of increased initial gland uptake rather than group differences in blood kinetics. The {sup 124}I PET

  6. Aerial gamma spectrometry of the uranium province of Lagoa Real (Caetite, BA, Brazil): go environmental aspects and distribution of the absorbed dose in the air; Espectrometria gama aerea da provincia uranifera de Lagoa Real (Caetite, BA): aspectos geoambientais e distribuicao da dose absorvida no ar

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Esau Francisco Sena

    2006-07-01

    In the present study, it was analyzed the surface concentrations of the natural radioelements K, U and Th, as well as the absorbed dose rate in air caused by gamma radiation from the Lagoa Real uranium province, which is located at the center southern portion of Bahia State and comprises an area of approximately 4.600 Km{sup 2}. Data from the airborne gamma ray spectrometric survey of the region (Sao Timoeo Project) carried out in 1979, was used in this study. Besides, recent data of U, Th and absorbed dose rates from the Environmental Monitoring Program of the uranium concentration plant (URA), operated in the region by the Brazilian Nuclear Industries (INB), were used with the aim of inter compare the sampling points in the same geo referenced area. Imaging geo processing software's give support to frame maps of surface concentrations and ternary maps, as well as allow the integration of these with other themes (e.g. hydrology, geology, pedology) favouring the interpretation of geo environmental process from the radioactive cartography. Considering the whole study area, it was obtained the following mean values: absorbed dose rate in air (61,08 nGy.h{sup -1}), Potassium (1,65 % K) , Uranium (3,02 ppm eU) and thorium (18,26 ppm eTh). The geological unities bounding the uranium anomalies were placed in the areas characterized by the highest values of radioelements and, as expected, the major dose levels. The use of ternary maps coupled with the geology and hydrology allowed distinguishing the relationship between the surface distribution of natural radioelements and the geo environmental aspects, including the influence of the catchment in their transport and migration. (author)

  7. 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

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Erik; Ljungberg, Michael; Martensson, Linda; Nilsson, Rune; Tennvall, Jan; Strand, Sven-Erik; Joensson, Bo-Anders [Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund (Sweden); Department of Oncology, Clinical Sciences, Lund University, Lund (Sweden); Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund (Sweden)

    2012-07-15

    Purpose: Biokinetic and dosimetry studies in laboratory animals often precede clinical radionuclide therapies in humans. A reliable evaluation of therapeutic efficacy is essential and should be based on accurate dosimetry data from a realistic dosimetry model. The aim of this study was to develop an anatomically realistic dosimetry model for Brown Norway rats to calculate S factors for use in evaluating correlations between absorbed dose and biological effects in a preclinical therapy study. Methods: A realistic rat phantom (Roby) was used, which has some flexibility that allows for a redefinition of organ sizes. The phantom was modified to represent the anatomic geometry of a Brown Norway rat, which was used for Monte Carlo calculations of S factors. Kinetic data for radiolabeled BR96 monoclonal antibodies were used to calculate the absorbed dose. Biological data were gathered from an activity escalation study with {sup 90}Y- and {sup 177}Lu-labeled BR96 monoclonal antibodies, in which blood cell counts and bodyweight were examined up to 2 months follow-up after injection. Reductions in white blood cell and platelet counts and declines in bodyweight were quantified by four methods and compared to the calculated absorbed dose to the bone marrow or the total body. Results: A red marrow absorbed dose-dependent effect on hematological parameters was observed, which could be evaluated by a decrease in blood cell counts. The absorbed dose to the bone marrow, corresponding to the maximal tolerable activity that could safely be administered, was determined to 8.3 Gy for {sup 177}Lu and 12.5 Gy for {sup 90}Y. Conclusions: There was a clear correlation between the hematological effects, quantified with some of the studied parameters, and the calculated red marrow absorbed doses. The decline in body weight was stronger correlated to the total body absorbed dose, rather than the red marrow absorbed dose. Finally, when considering a constant activity concentration, the phantom

  8. Applicability of a prototype for determination of absorbed dose using brachytherapy equipment with Ir-192 sources; Aplicabilidade de um prototipo para determinacao da dose absorvida utilizando equipamentos de braquiterapia com fontes de IR-192

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Vivianne Lucia Bormann; Almeida, Mayara Gabriella Oliveira de; Vieira, Rafaela Etelvina de Amorim; Silva, Waldecy Ananias da; Nascimento, Rizia Keila, E-mail: vlsouza@cnen.gov.br, E-mail: mayaradqf@hotmail.com, E-mail: rodriguesss@hootmail.com, E-mail: waldecy@cnen.gov.br, E-mail: riziakeila@hotmail.com [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2014-07-01

    This work aims at the development and improvement of a device to perform the absolute dosimetry sources of Ir-192 using the Fricke solution contained in a flask. The Fricke solution used was prepared using amounts of ferrous ammonium sulfate, sodium chloride and sulfuric acid, diluted with water tri distilled pre-established in the literature. The spectrophotometer used was a UV-VIS spectrophotometer (Beckman DU-640 Counter) for measuring the optical density at wavelength 304 nm. The calculation for determining the radial dose takes into account the radial distance and the angle formed with the transverse axis of the source. As the results obtained can be seen that the states of Pernambuco, Ceara, Paraiba e Piaui are in accordance with the recommendations of international standards of the International Atomic Energy Agency (IAEA), which considers not acceptable a difference greater than 5% of prescribed dose and measured dose.

  9. Development of a multi-electrode extrapolation chamber as a prototype of a primary standard for the realization of the unit of the absorbed dose to water for beta brachytherapy sources

    CERN Document Server

    Bambynek, M

    2002-01-01

    The prototype of a primary standard has been developed, built and tested, which enables the realization of the unit of the absorbed dose to water for beta brachytherapy sources. In the course of the development of the prototype, the recommendations of the American Association of Physicists in Medicine (AAPM) Task Group 60 (TG60) and the Deutsche Gesellschaft fuer Medizinische Physik (DGMP) Arbeitskreis 18 (AK18) were taken into account. The prototype is based on a new multi-electrode extrapolation chamber (MEC) which meets, in particular, the requirements on high spatial resolution and small uncertainty. The central part of the MEC is a segmented collecting electrode which was manufactured in the clean room center of PTB by means of electron beam lithography on a wafer. A precise displacement device consisting of three piezoelectric macrotranslators has been incorporated to move the wafer collecting electrode against the entrance window. For adjustment of the wafer collecting electrode parallel to the entranc...

  10. Report on EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 (EUROMET project no. 813): Comparison of air kerma and absorbed dose to water measurements of {sup 60}Co radiation beams for radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Csete, I. [National Office of Measures (OMH) - pilot laboratory and corresponding author (Hungary); Leiton, A.G. [Research Centre for Energy, Environment and Technology (CMRI-CIEMAT) (Spain); Sochor, V. [Czech Metrology Institute (CMI) (Czech Republic); Lapenas, A. [Latvian National Metrology Center (LNMC-RMTC) (Latvia); Grindborg, J.E. [Swedish Radiation Protection Authority (SSI) (Sweden); Jokelainen, I. [Radiation and Nuclear Safety Authority (STUK) (Finland); Bjerke, H. [Norwegian Radiation Protection Authority (NRPA) (Norway); Dobrovodsky, J. [Slovak Institute of Metrology (SMU) (Slovakia); Megzifene, A. [International Atomic Energy Agency, IAEA, Vienna (Austria); Hourdakis, C.J. [Hellenic Atomic Energy Committee (HAEC-HIRCL) (Greece); Ivanov, R. [National Centre of Metrology (NCM) (Bulgaria); Vekic, B. [Rudjer Boskovic Institute (IRB) (Croatia); Kokocinski, J. [Central Office of Measures (GUM) (Poland); Cardoso, J. [Institute for Nuclear Technology (ITN-LMRIR) (Portugal); Buermann, L. [Physikalisch Technische Bundesanstalt (PTB) (Germany); Tiefenboeck, W. [Bundesamt fur Eich und Vermesungswesen (BEV) (Austria); Stucki, G. [17 Bundesamt fur Metrologie (METAS) (Switzerland); Van Dijk, E. [NMi Van Swinden Laboratorium (NMi) (Netherlands); Toni, M.P. [ENEA-CR Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti (ENEA) (Italy); Minniti, R. [20 National Institute of Standards and Technology (NIST) (United States); McCaffrey, J.P. [National Research Council Canada (NRC) (Canada); Silva, C.N.M. [National Metrology Laboratory of Ionizing Radiation (LNMRI-IRD) (Brazil); Kharitonov, I. [D I Mendeleyev Institute for Metrology (VNIIM) (RU); Webb, D. [Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) (Australia); Saravi, M. [National Atomic Energy Commission (CNEA-CAE) (Argentina); Delaunay, F. [Laboratoire National Henri Becquerel (LNE-LNHB) (France)

    2010-06-15

    The results of an unprecedented international effort involving 26 countries are reported. The EUROMET.RI(I)-K1 and EUROMET.RI(I)-K4 key comparisons were conducted with the goal of supporting the relevant calibration and measurement capabilities (CMC) planned for publication by the participant laboratories. The measured quantities were the air kerma (K{sub air}) and the absorbed dose to water (Dw) in {sup 60}Co radiotherapy beams. The comparison was conducted by the pilot laboratory MKEH (Hungary), in a star-shaped arrangement from January 2005 to December 2008. The calibration coefficients of four transfer ionization chambers were measured using two electrometers. The largest deviation between any two calibration coefficients for the four chambers in terms of air kerma and absorbed dose to water was 2.7% and 3.3% respectively. An analysis of the participant uncertainty budgets enabled the calculation of degrees of equivalence (DoE), in terms of the deviations of the results and their associated uncertainties. As a result of this EUROMET project 813 comparison, the BIPM key comparison database (KCDB) will include eleven new Kair and fourteen new D{sub w} DoE values of European secondary standard dosimetry laboratories (SSDLs), and the KCDB will be updated with the new DoE values of the other participant laboratories. The pair-wise degrees of equivalence of participants were also calculated. In addition to assessing calibration techniques and uncertainty calculations of the participants, these comparisons enabled the experimental determinations of N{sub Dw}/N{sub Kair} ratios in the {sup 60}Co gamma radiation beam for the four radiotherapy transfer chambers. (authors)

  11. Biological assay of chromatin dispersal simplified for determining absorbed dose of ionizing radiation; Ensayo biologico simplificado de dispersion de cromatina para la determinacion de dosis de radiacion ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Galaz, S.; Perez, G.; Stockert, J. C.; Blazquez-Castro, A.

    2011-07-01

    Currently, the production of nuclear halos chromatin dispersion methods is a good procedure for nuclear analysis by in situ hybridization (Wiegant et al., 1992, Gerdes et al. 1994), to detect apoptosis, DNA fragmentation and cell death rates in cell cultures (Fernandez et al., 2005, Enciso et al. 2006). It is customary to display the nuclear halos by fluorescence microscopy using propidium iodide, ethidium bromide or DAPI (Gerdes et al., 1994, Sestili et al. 2006). Using this technique based on a modified protocol of fast halo assay [FHA],(Sestili et al. 2006), has developed a simplified method to quantify the cytogenetic damage induced by ionizing radiation (dispersion test chromatin in agarose thin smear), which allows visualization of halos after staining for light microscopy or fluorescence and correlating the ratio: total area occuped by the halo nucleus / nucleus (halo-core index [IHN] ) with radiation dose.

  12. QUANTITATIVE DETECTION OF ABSORBED DOSE OF IRRADIATED DRIED FRUIT BY ESR SPECTROSCOPY METHOD%ESR法定量检测干果类辐照食品

    Institute of Scientific and Technical Information of China (English)

    李伟明; 哈益明; 赵永富; 张彦立

    2011-01-01

    以葵花籽、核桃、开心果和榛子为试验材料,研究在0、1.0、3.0、5.0和10.0kGy剂量范围内4种样品辐照剂量与信号强度的关系以及相关性.结果表明:4种样品在辐照前后ESR波谱有明显区别,其信号强度与辐照剂量均呈正相关.辐照后样品的ESR强度和谱形都发生变化,应用ESR法能够鉴定4种食品是否经过辐照.其中核桃和开心果的ESR谱线中心信号左右两侧出现的2个对称小峰证明了纤维素自由基的存在.研究得出核桃的最低检出剂量接近1kGy,其余3种样品的检出剂量更低.本研究证明,应用ESR法能够定量检测干果类食品的吸收剂量.%Sunflower seeds, walnuts, pistachios, and hazelnuts were used as experimental materials which were irradiated at 1.0, 3.0, 5.0 and 10. 0kGy, respectively. The relationships and correlations between ESR signal intensity and irradiation dosages were studied. The results showed that ESR spectra of irradiated samples were obviously different from that of CK, and the ESR signal intensity was positively related with the irradiation dose. After irradiation, the ESR intensity and spectrum shapes all changed, and all four samples were clearly identified irradiated or unirradiated. The appearances of the two weak satellite lines which situated left and right to the intense singlet line in walnuts and pistachios proved the existence of cellulose radical. The detection dose limit of irradiated walnut was 1 kGy, and the detection limits of the other three samples were lower than 1 kGy. In conclusion, the ESR method could be used to irradiated.

  13. Comparação entre fatores de calibração em termos de dose absorvida no ar para uma câmara de ionização de placas paralelas Comparison of absorbed dose to air calibration factors for a parallel plate ionization chamber

    Directory of Open Access Journals (Sweden)

    Roseli T. Bulla

    2006-06-01

    Full Text Available OBJETIVO: O objetivo deste trabalho foi realizar uma comparação entre os fatores de calibração em termos de dose absorvida no ar determinados em feixes gama (60Co e de elétrons. MATERIAIS E MÉTODOS: Foram utilizados um irradiador de 60Co e um acelerador linear Varian, modelo Clinac 2100C, com feixes de fótons e de elétrons. Foram testadas uma câmara de ionização cilíndrica e três de placas paralelas. RESULTADOS: Os sistemas de medidas foram submetidos aos testes preliminares (estabilidade de resposta e corrente de fuga, com resultados muito bons. Os fatores de calibração em termos de dose absorvida no ar foram determinados utilizando-se quatro sistemas de medidas e dois tipos de objetos simuladores, com a obtenção de resultados dentro das recomendações internacionais. CONCLUSÃO: Os resultados mostraram que os fatores de calibração em termos de dose absorvida no ar obtidos para câmaras de ionização de placas paralelas, determinados em feixes de 60Co, são no máximo 1,2% mais altos que os valores obtidos em feixes de elétrons de altas energias.OBJECTIVE: The objective of this study was to compare the absorbed dose to air calibration factors determined in gamma (60Co and electron beams. MATERIALS AND METHODS: An irradiator with a 60Co source and a Varian, Clinac 2100C linear accelerator with photon and electron beams were utilized. One thimble-type and three parallel-plate ionization chambers were tested. RESULTS: The measurement systems were submitted to preliminary tests (response stability and leakage current, with quite good results. The absorbed dose to air calibration factors were determined using four measurement systems and two types of phantoms. Results were obtained in compliance with the international recommendations. CONCLUSION: Absorbed dose to air calibration factors obtained for parallel plate ionization chambers, determined in 60Co beams, at maximum, are 1.2% higher than the values obtained in high energy

  14. Determination of absorbed dose in water: evaluation of dosimetric factors calibration sets used in radiotherapy; Determinacao da dose absorvida na agua: avaliacao dos fatores de calibracao de conjuntos dosimetricos de uso em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Marco A.R. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil). Faculdade de Medicina. Departamento de Dermatologia e Radioterapia; Fontana, Julia M.; Santos, Vitor H.P.; Nunes, Isabella P.F.; Okawabata, Francine S., E-mail: marfernandes@fmb.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil). Instituto de Biociencia

    2014-12-15

    This paper presents a methodology for measuring the dose rate (cGy/min) in a telecobaltotherapy beam, looking emphasize the need for calibration of dosimetric set used and the importance of conducting periodic clinical megavoltage dosimetry of these beams. Two dosimetric set with their respective calibration factors were used. The correction parameters indicated in dosimetry protocols were determined by ionization chambers used. The difference between the value of the dose rate used in the calculation of the service routine and the values obtained in this work with both dosimetric sets proved to be less than 1.5%, and therefore satisfies the maximum recommended tolerance on quality control protocols for this type of therapeutic beam. (author)

  15. Study of the heterogeneity effects of lung in the evaluation of absorbed dose in radiotherapy; Estudo dos efeitos da heterogeneidade de pulmao na avaliacao da dose absorvida em radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Luciana Tourinho

    2006-02-15

    The main objective of radiotherapy is to deliver the highest possible dose to the tumour, in order to destroy it, reducing as much as possible the doses to healthy tissues adjacent to the target volume. Therefore, it is necessary to do a planning of the treatment. The more complex is the treatment, the more difficult the planning will be, demanding computation sophisticated methods in its execution, in order to consider the heterogeneities present in the human body. Additionally, with the appearing of new radiotherapeutic techniques, that used irradiation fields of small area, for instance, the intensity modulated radiotherapy, the difficulties for the execution of a reliable treatment planning, became still larger. In this work it was studied the influence of the lung heterogeneity in the planning of the curves of percentage depth dose, PDP, obtained with the Eclipse{sup R} planning system for different sizes of irradiation fields, using the correction algorithms for heterogeneities available in the planning system: modified Batho, general Batho and equivalent tissue-air ratio. A thorax phantom, manufactured in acrylic, containing a region made of cork to simulate the lung tissue, was used. The PDP curves generated by the planning system were compared to those obtained by Monte Carlo simulation and with the use of thermoluminescent, TL, dosimetry. It was verified that the algorithms used by the Eclipse{sup R} system for the correction of heterogeneity effects are not able to generate correct results for PDP curves in the case of small fields, occurring differences of up to 100%, when the 1x1 cm{sup 2} treatment field is considered. These differences can cause a considerable subdosage in the lung tissue, reducing the possibility of the patient cure. (author)

  16. Study of dose levels absorbed by members of the public in the nuclear medicine departments; Estudo dos niveis de dose em individuos do publico nos servicos de medicina nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Geovanna Oliveira de Mello

    2001-03-01

    In nuclear Medicine, radioisotopes are bound to various compounds (called radiopharmaceuticals) for use in various diagnostic and therapeutic applications. These unsealed sources are administered in various forms to patients, who remain radioactive for hours or days, and represent a source of potential radiation exposure for others. Thus, in nuclear medicine departments, radiation protection of workers and members of the public, especially persons accompanying patients, must consider, this exposure. In Brazil, the Comissao Nacional de Energia Nuclear (CNEN) establishes that, in nuclear medicine departments, the patients and persons accompanying should be separated each other. However, this rule is not always followed due to many factors such as physical and emotional conditions of patients. In this context, the aim of this study was the investigation of dose levels, which the persons accompanying patients are exposed to. For monitoring, thermoluminescent dosimeters were employed. The dosimeters were given to 380 persons who were accompanying patients in nuclear medicine departments. Exposure results were lower than 1 mSv. On the basis of CNEN rules, issues regarding stay conditions for members of the public in these departments are discussed. (author)

  17. Verificação das doses de radiação absorvidas durante a técnica de irradiação de corpo inteiro nos transplantes de medula óssea, por meio de dosímetros termoluminescentes Measurement of absorbed radiation doses during whole body irradiation for bone marrow transplants using thermoluminescent dosimeters

    Directory of Open Access Journals (Sweden)

    Adelmo José Giordani

    2004-10-01

    Full Text Available OBJETIVO: Avaliar a precisão das doses de radiação absorvidas na terapia de transplantes de medula óssea durante a técnica de irradiação de corpo inteiro. MATERIAIS E MÉTODOS: Utilizaram-se 200 pastilhas de sulfato de cálcio com disprósio compactado com teflon (CaSO4 + teflon, calibradas no ar e no "phantom", selecionadas aleatoriamente e dispostas em grupos de cinco no corpo dos pacientes. As leituras dosimétricas foram efetuadas pela leitora Harshaw 4000A. Nove pacientes foram irradiados no corpo inteiro em paralelos e em opostos laterais, utilizando-se unidade de cobalto-60, modelo Alcion II, com taxa de dose de 0,80 Gy/min a 80,5 cm, {campo (10 × 10 cm²}. A dosimetria dessa unidade foi realizada com dosímetro Victoreen 500. Para a determinação da dose média em cada ponto avaliado usaram-se os fatores individuais de calibração das pastilhas no ar e no "phantom", colocando-se um "build up" de 2 mm para superficializar a dose à distância de 300 cm. RESULTADOS: Em 70% dos pacientes obteve-se variação de dose menor que 5% e em 30% dos pacientes essa variação foi inferior a 10%, quando comparados os valores medidos com aqueles calculados em cada ponto. Na cabeça ocorre absorção, em média, de 14% da dose administrada, e nos pulmões, acréscimo de 2% na dose administrada. Nos pacientes com distância látero-lateral maior que 35 cm as variações entre as doses calculadas e medidas podem chegar a 30% da dose desejada, sem o uso de filtros compensadores. CONCLUSÃO: Os valores medidos das doses absorvidas nos diversos pontos anatômicos, comparados aos valores desejados (teóricos, apresentam tolerância de ±10%, considerando-se as diferenças anatômicas existentes, quando utilizados os fatores de calibração individuais das pastilhas.OBJECTIVE: To evaluate the precision of the absorbed radiation doses in bone marrow transplant therapy during whole body irradiation. MATERIALS AND METHODS: Two-hundred CaSO4:Dy + teflon

  18. Key comparison BIPM.RI(I)-K6 of the standards for absorbed dose to water of the LNE-LNHB, France and the BIPM in accelerator photon beams

    Science.gov (United States)

    Picard, S.; Burns, D. T.; Roger, P.; Delaunay, F.; Gouriou, J.; Le Roy, M.; Ostrowsky, A.; Sommier, L.; Vermesse, D.

    2013-01-01

    A comparison of the dosimetry for accelerator photon beams was carried out between the Laboratoire National de Métrologie et d'Essais-Laboratoire National Henri Becquerel (LNE-LNHB) and the Bureau International des Poids et Mesures (BIPM) in March 2012. The comparison was based on the determination of absorbed dose to water for three radiation qualities at the LNE-LNHB. The comparison result, reported as a ratio of the LNE-LNHB and the BIPM evaluations, is 0.995 at 6 MV and 12 MV; 0.994 at 20 MV, with a combined standard uncertainty of 5 parts in 103 at all three energies. This result is the fourth in the on-going BIPM.RI(I)-K6 series of comparisons. 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).

  19. Determination of absorbed dose in crystalline and thyroid gland with irradiation protocols applied in orthopantomography equipment for dental examination; Determinacion de dosis absorbida en cristalino y glandula tiroides con protocolos de irradiacion aplicados en equipos de ortopantomografia para panoramica dental

    Energy Technology Data Exchange (ETDEWEB)

    Munoz A, A. A.; Ramirez A, L. M. [Instituto Tecnologico Metropolitano, Grupo de Investigacion e Innovacion Biomedica, Medellin, Antioquia (Colombia); Sosa A, M. A.; Azorin V, J. C.; Vallejo H, M. A. [Universidad de Guanajuato, Departamento de Fisica, Loma del Bosque 103, Lomas del Campestre, 37150 Leon, Guanajuato (Mexico)

    2016-10-15

    Ionizing radiations are very useful in the medical field for the diagnostic use of different pathologies. Currently there are different technologies for diagnostic imaging using conventional X-ray, computed tomography, mammography, angiography, dental panoramic X-ray, among others. However, it should be noted that exposure to radiation in this type of diagnostic tests has increased considerably in recent years, because radiological examinations are not always carried out according to the actual clinical needs of each patient, increasing the risk to develop cancer. In this paper, the absorbed dose in the lens and thyroid gland was measured with the help of TLD-100 dosimeters located in a PMMA phantom adapted for orthopantomography (dental panoramic X-ray) equipment in 5 hospitals; using the parameters pre-configured for normal adult for irradiation. A Harshaw 3500 equipment was used to read the dosimeters, obtaining a value of 1.324 ± Sd 0.01 mGy for crystalline and 1.044 ± Sd 0.03 mGy values which are intended to be validated under other conditions and protocols. (Author)

  20. Calculus of the fluence and the absorbed dose by the different head tissues before photons of distinct energies; Calculo de la fluencia y la dosis absorbida por los diferentes tejidos de la cabeza ante fotones de distintas energias

    Energy Technology Data Exchange (ETDEWEB)

    Azorin V, C.; Rivera M, T. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, IPN, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Azorin N, J. [Departamento de Fisica, Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)], e-mail: claudiaazorin@yahoo.com.mx

    2009-10-15

    Two models were used, in the first one the head was built with the scalp that includes the skin and the adipose tissue, the skull, the brain and the tumor, it is modeled as a sphere of 1 cm of radius that be places in the center of the head pattern. The spherical models of the scalp, the skull and the brain were built respectively with spheres of 8.5, 8 and 7 cm of radius. The tumor was irradiated with an unidirectional beam of photons, the calculated cases were photons of {sup 6}0Co and monoenergetic photons beams of 6, 8, 10 and 15 MeV. For each case be calculated the total photons fluence to 5, 10 and 15 cm in air and to 20.5 cm that is the interface between the air and head. This calculus included values of photons fluence halfway the scalp, halfway the skull, halfway the brain and in the tumor center. Also is calculated the total absorbed dose by the scalp, the skull, the brain and the tumor. (author)

  1. Effect of absorbed dose on radiation crosslinking polyhedral oligomeric silsesquioxane/poly (urethane-imide) nano-composite foam%吸收剂量对多面体低聚倍半硅氧烷/聚(氨酯-酰亚胺)辐射共交联纳米复合泡沫材料的影响

    Institute of Scientific and Technical Information of China (English)

    周成飞; 曹巍; 翟彤; 曾心苗; 郭建梅

    2013-01-01

    以甲基丙烯酸β-羟乙酯和乙烯基多面体低聚倍半硅氧烷(POSS)为原料,采用一步法制得POSS/聚(氨酯-酰亚胺)纳米复合泡沫材料,研究了γ射线吸收剂量对纳米复合泡沫材料性能的影响.结果表明,在吸收剂量为50 kGy的条件下辐照,材料表现出最好的热稳定性;纳米复合泡沫材料玻璃态区的储能模量最高,损耗模量也遵循同样规律,但在75 kGy条件下损耗峰值最高.另外,吸声性能、阻燃性能和压缩强度都随着吸收剂量的增大而提高.%The polyhedral oligomeric silsesquioxane ( POSS)/poly( urethane-imide) ( PUI) was prepared by one-step method with 2-hydrooxyethyl methacrylate and vinyl-POSS as materials. The effect of absorbed dose of γ-ray on the properties of the nano-composite foam was investigated. The results showed that the thermal stability of radiation crosslinking POSS/PUI nano-composite foam was the best when absorbed dose was 50 kGy. The storage modulus in glassy zone of nano-composite foam was the hightest when absorbed dose was 50 kGy, while the loss modulus in glassy zone followed the same rule, but the loss peak value reached the maximun when absorbed dose was 75 kGy. Besides, the acoustic properties, flame retardance and compressive strength of nano-composite foam increased with the increase of absorbed dose.

  2. Adaptation of penelope Monte Carlo code system to the absorbed dose metrology: characterization of high energy photon beams and calculations of reference dosimeter correction factors; Adaptation du code Monte Carlo penelope pour la metrologie de la dose absorbee: caracterisation des faisceaux de photons X de haute energie et calcul de facteurs de correction de dosimetres de reference

    Energy Technology Data Exchange (ETDEWEB)

    Mazurier, J

    1999-05-28

    This thesis has been performed in the framework of national reference setting-up for absorbed dose in water and high energy photon beam provided with the SATURNE-43 medical accelerator of the BNM-LPRI (acronym for National Bureau of Metrology and Primary standard laboratory of ionising radiation). The aim of this work has been to develop and validate different user codes, based on PENELOPE Monte Carlo code system, to determine the photon beam characteristics and calculate the correction factors of reference dosimeters such as Fricke dosimeters and graphite calorimeter. In the first step, the developed user codes have permitted the influence study of different components constituting the irradiation head. Variance reduction techniques have been used to reduce the calculation time. The phase space has been calculated for 6, 12 and 25 MV at the output surface level of the accelerator head, then used for calculating energy spectra and dose distributions in the reference water phantom. Results obtained have been compared with experimental measurements. The second step has been devoted to develop an user code allowing calculation correction factors associated with both BNM-LPRI's graphite and Fricke dosimeters thanks to a correlated sampling method starting with energy spectra obtained in the first step. Then the calculated correction factors have been compared with experimental and calculated results obtained with the Monte Carlo EGS4 code system. The good agreement, between experimental and calculated results, leads to validate simulations performed with the PENELOPE code system. (author)

  3. Composite absorbing potentials

    CERN Document Server

    Palao, J P; Sala, P R

    1998-01-01

    The multiple scattering interferences due to the addition of several contiguous potential units are used to construct composite absorbing potentials that absorb at an arbitrary set of incident momenta or for a broad momentum interval.

  4. The ALICE absorbers

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Weighing more than 400 tonnes, the ALICE absorbers and the surrounding support structures have been installed and aligned with a precision of 1-2 mm, hardly an easy task but a very important one. The ALICE absorbers are made of three parts: the front absorber, a 35-tonne cone-shaped structure, and two small-angle absorbers, long straight cylinder sections weighing 18 and 40 tonnes. The three pieces lined up have a total length of about 17 m.

  5. Absolute absorbed dose measurements with an array of ionization chambers as part of a routine procedure of quality control for the VMAT technique; Medidas de dosis absorbida absoluta con un array de camaras de ionizacion como parte de un procedimiento rutinario de control de calidad para la tecnica VMAT

    Energy Technology Data Exchange (ETDEWEB)

    Clemente Gutierrez, F.; Cabello Murillo, E.; Ramirez Ros, J. C.; Casa de Julian, M. A. de la

    2011-07-01

    Arcotheraphy techniques volumetric modulated (VMAT) treatments involve continuous variation of the gantry rotation speed, positions of the sheets and dose rate. Since all treatments are administered by continuous arcs, these techniques require quality control procedures to ensure quick and easy constancy of the calibration factor (total absorbed dose) for any gantry angle. We report here a simple method of quality control for the measurement of the calibration factor using an array of ionization chambers. The measurements were performed on a unit of 6 MV Elekta Synergy with VMAT, belonging to the Radiation Oncology service of the Defense Central Hospital Gomez Ulla.

  6. Calculation of the absorbed dose for contamination in skin imparted by beta radiation through the Varskin code modified for 122 isotopes of interest for nuclear medicine, nuclear plants and research; Calculo de dosis absorbida para contaminacion en piel impartida por radiacion beta mediante el codigo Varskin modificado para 122 isotopos de interes para medicina nuclear, plantas nucleares e investigacion

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, J.T

    1992-06-15

    In this work the implementation of a modification of the Varskin code for calculation of absorbed dose by contamination in skin imparted by external radiation fields generated by beta emitting is presented. The necessary data for the execution of the code are: isotope, dose depth, isotope activity, geometry type, source radio and time of integration of the isotope, being able to execute combinations of up to five radionuclides. This program it was implemented in Fortran 5 by means of the FFSKIN source program and the executable one in binary language BFFSKIN being the maximum execution time of 5 minutes. (Author)

  7. Characterization of the exradin A18 chamber ionization according to the IEC70631 standards. This work aims at the characterization of the Exradin model (Standard Imaging) A18 ionization chamber, according to the international standard IEC 607311. Intends to use the camera Exradin A18 for the quality control of a linear accelerator VARIAN model TrueBeam with capacity to produce beams of photons of high energy, unfiltered flatter (in later FFF) with high dose absorbed by pulse rate, why is verified, according to the mentioned standard IEC 60731, even under conditions of high dose absorbed by pulse rate, the efficiency of ion collection from this camera is within tolerances; Caracterizacion de la camara de ionizacion exradin A18 segun el estandar IEC70631. Estudio para haces de fotones sin filtro aplanador

    Energy Technology Data Exchange (ETDEWEB)

    Onses Segarra, A.; Puxeu Vaque, J.; Sancho Kolster, I.; Lizuain Arroyo, M. C.; Picon Olmos, C.

    2013-07-01

    This work aims at the characterization of the Exradin model (Standard Imaging) A18 ionization chamber, according to the international standard IEC 607311. Intends to use the camera Exradin A18 for the quality control of a linear accelerator VARIAN model TrueBeam with capacity to produce beams of photons of high energy, unfiltered flatter (in later FFF) with high dose absorbed by pulse rate, why is verified, according to the mentioned standard IEC 60731, even under conditions of high dose absorbed by pulse rate, the efficiency of ion collection from this camera is within tolerances. (Author)

  8. Advanced neutron absorber materials

    Science.gov (United States)

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  9. Absorbing Outflows in AGN

    Science.gov (United States)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  10. Evaluation of the absorbed dose during studies of the renal function due to I{sup 123} / I{sup 131} (hippuran) and In{sup 111} (DTPA); Evaluacion de la dosis absorbida durante estudios de la funcion renal debido a I{sup 123} / I{sup 131} (hippuran) e In{sup 111} (DPTA)

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, M.; Castillo, C.; Sarachaga, R.; Rojas, R.; Zelada, L.; Melendez, J.; Gomez, M. [Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Ciudad Universitaria, Trujillo (Peru); Diaz, E., E-mail: marvva@hotmail.com [Universidade Federal do Rio Grande do Sul, Av. Paulo Gamma 110, Bairro Farropilhas, Porto Alegre, RS 90040-060 (Brazil)

    2014-08-15

    Using the methodology MIRD and representation Cristy-Eckerman for kidneys, bladder, and whole body as organs of the bio-kinetics of I{sup 123} / I{sup 131} (hippuran) and the In{sup 111} (D PTA), the absorbed dose for studies of the renal function of adults due to the I{sup 123} is 0,0071 mGy/MBq where 88.16% corresponds to its auto-dose and 11,96% to the organs of their bio-kinetics; while for the I{sup 131} their dose is 0,032 mGy/MBq where 95,03% corresponds to its auto-dose and 4,97% to the organs of their bio-kinetics. For the In{sup 111} their dose is 0,0168 mGy/MBq where 71,68% corresponds to their auto-dose and 28,32% to the organs of their bio-kinetics. In all the cases the dosimetric contributions of the organs of the bio-kinetics (whole body and urinary bladder) are very significant, and this fundamentally is due to the photons of the whole body. (Author)

  11. Analysis of the absorbed dose in skin for head and neck intensity modulated radiation therapy treatments; Analisis de la dosis absorbida en piel en tratamientos de radioterapia de intensidad modulada en cabeza y cuello

    Energy Technology Data Exchange (ETDEWEB)

    Llorente Manso, M.; Vicente Toribio, T.

    2009-07-01

    Intensity Modulated Radiation Therapy is becoming a common technique for treatment of head and neck tumours. The use of inverse planning techniques can lead to an unwanted skin dose and toxicity increase. In this study we present a quantitative evaluation of such phenomenon and propose an optimization method for skin dose reduction to the level usual in conventional Conformal Radiotherapy. (Author) 10 refs.

  12. Measurement of extrapolation curves for the secondary pattern of beta radiation Nr. 86 calibrated in rapidity of absorbed dose for tissue equivalent by the Physikalisch Technische Bundesanstalt; Medicion de curvas de extrapolacion para el patron secundario de radiacion beta Nr. 86 calibrado en rapidez de dosis absorbida para tejido equivalente por el Physikalisch Technische Bundesanstalt

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, J.T

    1988-10-15

    The following report has as objective to present the obtained results of measuring - with a camera of extrapolation of variable electrodes (CE) - the dose speed absorbed in equivalent fabric given by the group of sources of the secondary pattern of radiation Beta Nr. 86, (PSB), and to compare this results with those presented by the calibration certificates that accompany the PSB extended by the primary laboratory Physikalisch Technische Bundesanstalt, (PTB), of the R.F.A. as well as the uncertainties associated to the measure process. (Author)

  13. TOMS Absorbing Aerosol Index

    Data.gov (United States)

    Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

  14. Multiband terahertz metamaterial absorber

    Institute of Scientific and Technical Information of China (English)

    Gu Chao; Qu Shao-Bo; Pei Zhi-Bin; Xu Zhuo; Liu Jia; Gu Wei

    2011-01-01

    This paper reports the design of a multiband metamaterial (MM) absorber in the terahertz region. Theoretical and simulated results show that the absorber has four distinct and strong absorption points at 1.69, 2.76, 3.41 and that the impedance of MM could be tuned to match approximately the impedance of the free space to minimise the reflectance at absorption frequencies and large power loss exists at absorption frequencies. The distribution of the power loss indicates that the absorber is an excellent electromagnetic wave collector: the wave is first trapped and reinforced in certain specific locations and then consumed. This multiband absorber has applications in the detection of explosives and materials characterisation.

  15. Electrodynamic absorber theory

    OpenAIRE

    Deckert, Dirk-André

    2010-01-01

    This work deals with questions that arise in classical and quantum electrodynamics when describing the phenomena of radiation reaction and pair creation. The two guiding ideas are the absorber idea of Wheeler and Feynman (i.e. all emitted radiation will be again be absorbed by matter) and the electron sea idea of Dirac. In the first part classical dynamics are studied which allow for a description of radiation reaction without the need of renormalization. The starting point are the couple...

  16. Evaluation of absorbed dose in studies of renal function due to {sup 123}I/{sup 131}I (hippuran) e {sup 111}In (DPTA); Evaluacion de la dosis absorbida durante estudios de la funcion renal debido al {sup 123}I/{sup 131}I (hippuran) e {sup 111}In (DPTA)

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, M.V.; Castillo, C.E.; Rojas, R.; Cabrera, C.; Abanto, D.; Morgan, A. [Universidad Nacional de Trujillo (UNT), Area de Fisica Medica, Trujillo (Peru); Diaz, E.E., E-mail: marvva@hotmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre (Brazil)

    2015-07-01

    The absorbed dose of the kidneys during renal function studies of adult patients is estimated through biokinetics of radiopharmaceuticals containing the {sup 123}I/{sup 131}I (hippuran) e {sup 111}In (DPTA). Using the methodology MIRD and representation Cristy-Eckerman for adult kidneys, it is shown that dosimetric contributions of organs of biokinetics {sup 123}I/{sup 131}I (hippuran) e {sup 111}In (DPTA) are significant, in estimative of dose for renal function studies. Dosimetric contributions (body and whole bladder, kidneys excluding) are given by 11.90% (for {sup 123}I), 4.97% (for {sup 131}I) and 28.32% (for {sup 111}In). In all cases, the dosimetric contributions are mainly due to photons issued by the whole body.

  17. Neutron absorbing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Masayuki

    1998-12-04

    The neutron absorbing alloy of the present invention comprises Ti or an alloy thereof as a mother material, to which from 2 to 40% by weight of Hf and Gd within a range of from 4 to 50% by weight in total are added respectively. Ti is excellent in specific strength, corrosion resistance and workability, and produces no noxious intermetallic compound with Hf and Gd. In addition, since the alloy can incorporate a great quantity of Hf and Gd, a neutron absorbing material having excellent neutron absorbing performance than usual and excellent in specific strength, corrosion resistance and workability can be manufactured conveniently and economically not by a special manufacturing method. (T.M.)

  18. Metasurface Broadband Solar Absorber

    CERN Document Server

    Azad, A K; Sykora, M; Weisse-Bernstein, N R; Luk, T S; Taylor, A J; Dalvit, D A R; Chen, H -T

    2015-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. Furthermore, we discuss the potential use of our metasurface absorber design in solar thermophotovoltaics by exploiting refractory plasmonic materials.

  19. Unidirectional perfect absorber

    Science.gov (United States)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  20. Differences in absorbed doses at risk organs and target tumoral of planning(PTV) in lung treatments using two algorithms of different calculations; Diferencias en las dosis absorbidas en organos de riesgo y volumen tumoral de planificacion (PTV) en tratamientos de pulmon usando dos algoritmos de calculo diferentes: pencil beam y collpased cone

    Energy Technology Data Exchange (ETDEWEB)

    Uruena Llinares, A.; Santos Rubio, A.; Luis Simon, F. J.; Sanchez Carmona, G.; Herrador Cordoba, M.

    2006-07-01

    The objective of this paper is to compare, in thirty treatments for lung cancer,the absorbed doses at risk organs and target volumes obtained between the two used algorithms of calculation of our treatment planning system Oncentra Masterplan, that is, Pencil Beams vs Collapsed Cone. For it we use a set of measured indicators (D1 and D99 of tumor volume, V20 of lung, homogeneity index defined as (D5-D95)/D prescribed, and others). Analysing the dta, making a descriptor analysis of the results, and applying the non parametric test of the ranks with sign of Wilcoxon we find that the use of Pencil Beam algorithm underestimates the dose in the zone of the PTV including regions of low density as well as the values of maximum dose in spine cord. So, we conclude that in those treatments in which the spine dose is near the maximum permissible limit or those in which the PTV it includes a zone with pulmonary tissue must be used the Collapse Cone algorithm systematically and in any case an analysis must become to choose between time and precision in the calculation for both algorithms. (Authors)

  1. Calculus of spatial distribution of absorbed dose to cellular level by Monte Carlo simulation for a radio-labelled peptide with {sup 188}Re and with nuclear internalization : preliminary results; Calculo de la distribucion espacial de dosis absorbida a nivel celular por simulacion Monte Carlo para un peptido radiomarcado con {sup 188}Re y con internalizacion nuclear : resultados preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E. L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Santos C, C. L. [Universidad Autonoma del Estado de Mexico, Paseo Tollocan y Jesus Carranza, Toluca 50120, Estado de Mexico (Mexico)], e-mail: leticia.rojas@inin.gob.mx

    2009-10-15

    The {sup 188}Re is a radionuclide of radiation gamma emitter, useful in obtaining of gamma-graphic images, but it is also emitter of beta radiations and Auger electrons. A bio-molecule directed to a specific receptor of a cancer cell labeled with a emitter radionuclide of beta particles and Auger electrons, as the {sup 188}Re-Tat-Bombesin, it has the potential to be used in radiotherapy of molecular targets for its capacity to penetrate to cellular nucleus. In this system, the radiation dose is distributed in way located at microscopic levels in sub cellular specific places, where Auger emissions contributes of significant way in absorbed dose. The cellular dosimetry is realized in most of cases, using analytic or semi analytical methods, for example the cellular MIRD methodology. However, it is required to complement these calculations simulating the electrons transport and considering experimental bio kinetics data. Therefore, in this work preliminary results are presented of dosimetric calculation to sub cellular level for {sup 188}Re-Tat-Bombesin by Monte Carlo simulation, using the 2008 version of PENELOPE: PENEASY code. The spatial distribution of absorbed dose in membrane, cytoplasm and nucleus, was calculated with geometry of a cell of 10 {mu}m of diameter, a nucleus of 2 {mu}m of ratio and membrane of 0.2 {mu}m of thickness, considering elementary constitution for each cellular compartment proposal in literature. The total number of disintegrations at sub cellular level was evaluated integrating the activity in function of time starting from experimental bio kinetics data in mamma cancer cells MDA-MB231. The preliminary results show that 46.4% of total disintegrations for unit of captured activity by cell occurs in nucleus, 38.4% in membrane and 15.2% in cytoplasm. The due absorbed dose to Auger electrons for 1 Bq of {sup 188}Re located in cellular membrane were respectively of 1.32E-1 and 1.43E-1 Gy in cytoplasm and nucleus. (Author)

  2. Absorbed dose in the fetus of a pregnant patient when I{sup 131} (iodide/Tc{sup 99m} (pertechnetate) is administered during thyroid studies; Dosis absorbida en el feto de una paciente embarazada cuando se administra I{sup 131} (yoduro)/Tc{sup 99m} (pertecnetato) durante estudios tiroideos

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez A, M.; Murillo C, V.; Arbayza F, J.; Sanchez S, P.; Cabrera S, C., E-mail: marvva@hotmail.com [Universidad Nacional de Trujillo, Laboratorio de Fisica Nuclear, Trujillo (Peru)

    2016-10-15

    The radiation absorbed dose in the fetus of a pregnant woman during thyroid studies is estimated through the analysis of the bio-kinetics of radiopharmaceuticals containing I{sup 131} (iodide) or Tc{sup 99m} (pertechnetate). MIRD formalism and its representation Cristy-Eckerman are used. The results indicate that the absorbed dose by the fetus of a woman of 3, 6 and 9 months of gestation due to Tc{sup 99m} emissions is lower than that obtained by I{sup 131}; represent 34.7%, 6% and 3.5% of the dose generate by the iodide. The auto-dose in the fetus of a pregnant woman is mainly due to the local energy deposition of the beta and gamma emissions of I{sup 131}, being greater than the one reported by the gamma emissions and conversion electrons of the Tc{sup 99m}, for fetuses of 6 and 9 months. The dose incorporated to the fetus due to the organs of the maternal tissues, which are part of the bio-kinetics, are basically due to the emission of its gamma photons and correspond to 38.50% /60.52% in fetuses of 3 months, 64.71% /12.43% in fetuses of 6 months and 69.79% /10.97% in fetuses of 9 months for the radiopharmaceuticals Tc{sup 99m} (pertechnetate) / I{sup 131} (iodide). The organs of bio-kinetics that contribute to the fetus dose are mainly due to the bladder, followed by the rest, and small intestine (fetuses of 3 months); of the rest, followed by the small intestine and bladder (fetuses of 6 months); of the bladder, followed by the small intestine and stomach (fetuses of 9 months) when using I{sup 131}; while for the Tc{sup 99m} the bladder and rest contribute (fetuses of 3 months); of the placenta, followed by the rest and bladder (fetuses of 6 and 9 months). (Author)

  3. Solar concentrator/absorber

    Science.gov (United States)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  4. Universal metamaterial absorbe

    CERN Document Server

    Smaali, Rafik; Moreau, Antoine; Taliercio, Thierry; Centeno, Emmanuel

    2016-01-01

    We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\\lambda/100$ thickness by a metamaterial layer and a mirror. An extraordinary large funneling through nano-slits explains how light can be trapped in the structure. Simple scaling laws can be used as a recipe to design ultra-thin perfect absorbers whatever the materials and the desired resonance wavelength, making our design truly universal.

  5. Optimal Sound Absorbing Structures

    CERN Document Server

    Yang, Min; Fu, Caixing; Sheng, Ping

    2016-01-01

    Causal nature of the acoustic response, for any materials or structures, dictates an inequality that relates the absorption spectrum of the sample to its thickness. We present a general recipe for constructing sound-absorbing structures that can attain near-equality for the causal relation with very high absorption performance; such structures are denoted optimal. Our strategy involves using carefully designed acoustic metamaterials as backing to a thin layer of conventional sound absorbing material, e.g., acoustic sponge. By using this design approach, we have realized a 12 cm-thick structure that exhibits broadband, near-perfect flat absorption spectrum starting at around 400 Hz. From the causal relation, the calculated minimum sample thickness is 11.5 cm for the observed absorption spectrum. We present the theory that underlies such absorption performance, involving the evanescent waves and their interaction with a dissipative medium, and show the excellent agreement with the experiment.

  6. Metamaterial Absorbers in Terahertz Band

    Institute of Scientific and Technical Information of China (English)

    Qi-Ye Wen; Huai-Wu Zhang; Qing-Hui Yang; Man-Man Mo

    2013-01-01

    In recent years, a great deal of effort has been made to a create terahertz (THz) wave absorber based on metamaterials (MM). Metamaterials absorbers have a variety of potential applications including thermal emitters, detector, stealth technology, phase imaging, etc. In this paper, we firstly introduce the basic structure and work principle of the THz MM absorbers, and a transmission line model is developed for devices analysis. To expand the application of THz absorbers, dual-band and broadband THz MM absorbers are designed, fabricated, and measured. At the end of this article, the future development trends of MM absorbers are discussed.

  7. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  8. The Flexible Bass Absorber

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contains high levels of bass sou...... has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design....

  9. The Flexible Bass Absorber

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian

    2007-01-01

    Multi-purpose concert halls face a dilemma. They host different performance types that require significantly different acoustic conditions in order to provide the best sound quality to both the performers, sound engineers and the audience. Pop and rock music often contain high levels of bass soun...... has been developed. Measurements were made on a variable and mobile low-frequency absorber. The paper presents the results of prototype sound absorption measurements as well as elements of the design....

  10. Clustering of Absorbers

    CERN Document Server

    Cristiani, S; D'Odorico, V; Fontana, A; Giallongo, E; Moscardini, L; Savaglio, S

    1997-01-01

    The observed clustering of Lyman-$\\alpha$ lines is reviewed and compared with the clustering of CIV systems. We argue that a continuity of properties exists between Lyman-$\\alpha$ and metal systems and show that the small-scale clustering of the absorbers is consistent with a scenario of gravitationally induced correlations. At large scales statistically significant over and under-densities (including voids) are found on scales of tens of Mpc.

  11. Ionized Absorbers in AGN

    Science.gov (United States)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  12. Theory of microslit absorbers

    Institute of Scientific and Technical Information of China (English)

    MAA Dah-You

    2001-01-01

    It is well known that narrow slit may be used as acoustical element. The exact formulae of the acoustical impedance of a narrow slit and its low-frequency approximation are available. The theory of slit is extended and a simple and practical formula is derived for the single slit. It is found that the resistance-to-reactance ratio of the slit increases to larger than one when the slit width is decreased to submillimeter range, and a panel with extremely narrow slits plus a back cavity will make an absorber with good absorption in a wide frequency range,without any porous or fibrous material. A complete theory of the microslit absorber (MSA) is, thus, presented and its absorption characteristics discussed. It is found that the MSA has essentially the same formulae as the microperforate absorber (MPA), except that the numerical coefficient of the resistance is smaller and the end correction for the mass reactance is larger for the MSA, resulting a performance inferior to that of MPA, ordinarily. Measures are proposed to compensate for these.

  13. Automation of the monitoring in real time of the absorbed dose rate in air due to the environmental gamma radiation in Cuba; Automatizacion del monitoreo en tiempo real de la tasa de dosis absorbida en aire debido a la radiacion gamma ambiental en Cuba

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez L, O.; Capote F, E.; Carrazana G, J.A.; Manzano de Armas, J.F.; Alonso A, D.; Prendes A, M.; Zerquera, J.T.; Caveda R, C.A. [CPHR, Calle 20, No. 4113 e/41 y 47, Playa, La Habana, 11300, A.P. 6195 C.P. 10600 (Cuba); Kalberg, O. [Swedish Radiation Protection Institute (SSI) (Sweden); Fabelo B, O.; Montalvan E, A. [CIAC, Camaguey (Cuba); Cartas A, H. [CEAC, Cienfuegos (Cuba); Leyva F, J.C. [CISAT (Cuba)]. e-mail: orlando@cphr.edu.cu

    2006-07-01

    The Center of Protection and Hygiene of the Radiations (CPHR) like center rector of the National Net of Environmental Radiological Surveillance (RNVRA), it has strengthened their detection capacity and of answer before a situation of radiological emergency. The measurements of the absorbed dose rate in air due to the environmental gamma radiation in the main stations of the Net are obtained in real time and the CPHR receives the data coming from these posts at one time relatively short. To improve the operability of the RNVRA it was necessary to complete the facilities of existent monitoring using 4 automatic measurement stations with probes of gamma detection, implementing in this way a measurement system on real time. On the other hand the software were developed: GenironProbeFech, to obtain the data of the probes, DataMail for the shipment of the same ones by electronic mail and GammaRed that receives and processes the data in the rector center. (Author)

  14. 应用Alexa Fluor 488与BHQ1双标记寡核苷酸荧光探针测量辐射吸收剂量的可行性研究%The feasibility study of radiation absorbed dose measurement using oligonucleotide dually labeled with Alexa Fluor 488 and BHQ1 probe

    Institute of Scientific and Technical Information of China (English)

    林温文; 史盼影; 张保国

    2016-01-01

    目的 研究荧光探针Alexa Fluor 488-DNA-BHQ1用于辐射吸收剂量测量的可行性.方法 在寡核苷酸的5 '与3’端分别标记荧光分子Alexa Fluor 488与其特异性荧光抑制剂BHQ1,制备Alexa Fluor 488-DNA-BHQ1的DNA双标记荧光探针.用X射线照射其水溶液,检测照射后溶液的荧光强度.结果 浓度为0.5~1 μmol/L时,该荧光探针对剂量0.1~30 Gy之间线性响应最好(R2=0.99).在辐照后40~80 min检测探针,荧光强度基本不变.4℃条件下保存受照后的荧光探针的荧光稳定性较好.结论 荧光探针Alexa Fluor 488-DNA-BHQ1可以应用于0.1 ~30 Gy范围内辐射吸收剂量的测量.%Objective To study the feasibility of measuring radiation absorbed dose with the fluorescent probe Alexa Fluor 488-DNA-BHQ1.Methods An oligonucleotide dually labeled at its 5'-and 3'-end with fluorescent molecular Alexa Fluor 488 and specific fluorescence inhibitors BHQ1 was prepared.The Alexa Fluor 488-DNA-BHQ1 aqueous solution was exposed with X-ray and its fluorescence intensity was measured.Results When the concentration of Alexa Fluor 488-DNA-BHQ1 was between 0.5 and 1 μmol/L,the fluorescence intensity of its aqueous solution had excellent linear dose response from 0.1 to 30 Gy (R2 =0.99) and it was stably maintained after 40-80 min of irradiation especially at 4℃.Conclusions In the dose range of 0.1-30 Gy,the Alexa Fluor 488-DNA-BHQ1 fluorescent probe can be used to measure radiation absorbed dose.

  15. Absorber for terahertz radiation management

    Science.gov (United States)

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  16. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  17. 基于统一计算架构的人体受照剂量实时仿真评估方法%Real-time absorbed dose simulation assessment method for the maintenance workers of nuclear facilities based on compute unified device architecture

    Institute of Scientific and Technical Information of China (English)

    杨子辉; 王静; 何桃; 宋婧; 龙鹏程

    2015-01-01

    基于统一计算架构(Compute unified device architecture, CUDA),利用GPU的流多处理器和共享显存实现了辐射环境中人体体素级受照剂量的并行计算。通过加速器驱动次临界系统散裂靶质子束窗的维修更换仿真例题的测试,百万量级体素人体受照剂量计算时间降低到10 ms的量级,能够保持与实时维修仿真同步。该方法能够满足维修仿真对维修人员的器官当量剂量和人体有效剂量计算的实时性要求,可应用到维修方案的实时仿真推演,对提高维修方案的设计与验证效率,辅助优化方案和保障人员辐射安全具有重要意义。%The absorbed dose assessment method was developed based on compute unified device architecture parallel architecture and human voxel model, to realize the parallel computing of radiation dose for human body in the radiation environment using the GPU processors and shared memory. The maintenance strategy simulation dose assessment of the spallation target proton beam window for accelerator driven system was tested by this method. The results showed that the computing time can reach 10 ms level with millions of voxel and the dose calculation can synchronize with real-time simulation of maintenance process.This method could realize the requirement of organ equivalent dose and effective dose calculation for maintenance worker. In the simulation deduction of maintenance strategy, this method is of great significance in protecting personnel radiation safety and improving the efficiency for  the design and validation of maintenance scheme.

  18. Sensing with THz metamaterial absorbers

    CERN Document Server

    Cong, Longqing

    2014-01-01

    Metamaterial perfect absorbers from microwaves to optical part of the electromagnetic spectrum has been intensely studied for its ability to absorb electromagnetic radiation. Perfect absorption of light by metamaterials have opened up new opportunities for application oriented functionalities such as efficient sensors and emitters. We present an absorber based sensing scheme at the terahertz frequencies and discuss optimized designs to achieve high frequency and amplitude sensitivities. The major advantage of a perfect metamaterial absorber as a sensor is the sensitive shift in the absorber resonance frequency along with the sharp change in the amplitude of the resonance due to strong interaction of the analyte with the electric and the magnetic fields at resonant perfect absorption frequency. We compare the sensing performance of the perfect metamaterial absorber with its complementary structural design and planar metasurface with identical structure. The best FoM values obtained for the absorber sensor here...

  19. Ferroelectrics based absorbing layers

    Science.gov (United States)

    Hao, Jianping; Sadaune, Véronique; Burgnies, Ludovic; Lippens, Didier

    2014-07-01

    We show that ferroelectrics-based periodic structure made of BaSrTiO3 (BST) cubes, arrayed onto a metal plate with a thin dielectric spacer film exhibit a dramatic enhancement of absorbance with value close to unity. The enhancement is found around the Mie magnetic resonance of the Ferroelectrics cubes with the backside metal layer stopping any transmitted waves. It also involves quasi-perfect impedance matching resulting in reflection suppression via simultaneous magnetic and electrical activities. In addition, it was shown numerically the existence of a periodicity optimum, which is explained from surface waves analysis along with trade-off between the resonance damping and the intrinsic loss of ferroelectrics cubes. An experimental verification in a hollow waveguide configuration with a good comparison with full-wave numerical modelling is at last reported by measuring the scattering parameters of single and dual BST cubes schemes pointing out coupling effects for densely packed structures.

  20. Absorbed fractions for electrons in ellipsoidal volumes

    Science.gov (United States)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  1. Liquid Hydrogen Absorber for MICE

    Energy Technology Data Exchange (ETDEWEB)

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  2. Measurement of dose speed absorbed in depth imparted by sources external secondary patterns of beta radiation. Part 1 Measurement of dose speed absorbed in the surface of soft fabric for isotopes of {sup 90}Sr/{sup 90}Y, {sup 147}Pm and {sup 204}TI; Medicion de rapidez de dosis absorbida en profundidad impartida por fuentes patrones secundarios de radiacion beta externos. Parte 1. Medicion de rapidez de dosis absorbida en la superficie de tejido blando para isotopos de {sup 90}Sr/{sup 90}Y, {sup 147}Pm y {sup 204}TI

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, J.T. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1993-01-15

    The dose speed was measured absorbed for depth zero, (superficial) in soft equivalent fabric, for the secondary pattern{sup s} four sources of beta radiation, (Nr. 86): {sup 90}Sr/{sup 90}Y, (1850 MBq and 74 MBq respectively); {sup 147}Pm, (518 MBq) and {sup 204}TI, (18.5 MBq). The measurement is carried out to different distances of source-detecting separation, (11.0, 30.0 and 50.0 cm for the source of 1850 MBq, 30.0 cm for that of 74 MBq; 11.00 cm for the source of {sup 147}Pmand to contact for all the sources); maintaining the radiation sheaf aligned the one axis of symmetry of the detector, ({alpha} 0 degrees). The detector employed was a extrapolation chambers of variable electrodes and electrode fixed collector, (30 mm of diameter). In accordance with the principle of Bragg-Gray the volume of the chambers is varied and they register the variations of the current of collected ionization, correcting until for a maximum of thirteen correction factors that take into account the deviation to the suppositions that it establishes this principle. The certain values of the speed of superficial absorbed dose are in the following intervals: {sup 90}Sr/{sup 90}Y, (1850 MBq, 0.0, 11.0, 30.0 and 50.0 cm): 43.164 mGy S-t, 0.544 mGy s-1 ,0.075 mGy s{sup -1} and 0.027 mGy s{sup -1}, respectively, with a Global Analysis of the order of 1.17%, 1.17%, 1.14% and 1.66%, K J; {sup 90}Sr / {sup 90}Y, (74 MBq, 0.0 and 30 cm): 1.536 mGy s{sup -1} and 0.002 mGy s{sup -1}, with Global Analysis of 1.19.0% and 5.22%, (K = 1) respectively, for the {sup 147}Pm, (0.0 and 11.0 in the interval of: 0.36 {mu}Gy s{sup -1} and 0.43 {mu}Gy s{sup -1}, with one Global Analysis of 1 .42% and 4.28%, (K = 1), respectively; and finally for the {sup 204}TI, (0.0 cm) in the interval of 0.10 {mu}Gy s{sup -1} with a Global Analysis of 1.27%. He calculates of the Global Analysis one carries out of agreement with those recommendations of the BIPM. In all the cases of source-detecting arrangement with

  3. Absorbed radiation by various tissues during simulated endodontic radiography

    Energy Technology Data Exchange (ETDEWEB)

    Torabinejad, M.; Danforth, R.; Andrews, K.; Chan, C.

    1989-06-01

    The amount of absorbed radiation by various organs was determined by placing lithium fluoride thermoluminescent chip dosimeters at selected anatomical sites in and on a human-like X-ray phantom and exposing them to radiation at 70- and 90-kV X-ray peaks during simulated endodontic radiography. The mean exposure dose was determined for each anatomical site. The results show that endodontic X-ray doses received by patients are low when compared with other radiographic procedures.

  4. Metamaterial Absorbers for Microwave Detection

    Science.gov (United States)

    2015-06-01

    ABSORBERS FOR MICROWAVE DETECTION by Michael T. McMahan June 2015 Thesis Advisor: Dragoslav Grbovic Co-Advisor: Richard C. Olsen THIS PAGE......presented. 14. SUBJECT TERMS metamaterials, metamaterial absorbers , metamaterial detectors 15. NUMBER OF PAGES 65 16. PRICE

  5. Improvement Of The Helmholtz Absorber

    Science.gov (United States)

    Morrow, Duane L.

    1992-01-01

    Helmholtz-resonator system improved to enable it to absorb sound at more than one frequency without appreciable loss of effectiveness at primary frequency. Addition of annular cavities enables absorption of sound at harmonic frequencies in addition to primary frequency. Improved absorber designed for use on structures of high transmission loss. Applied to such machines as fixed-speed engines and fans.

  6. Leaf absorbance and photosynthesis

    Science.gov (United States)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  7. Absorbent product to absorb fluids. [for collection of human wastes

    Science.gov (United States)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  8. Performance evaluation of the QC-6PLUS quality control system in terms of photons and electrons absorbed doses to water; Avaliacao do desempenho do sistema de controle da qualidade QC-6Plus em termos de dose absorvida na agua para fotons e eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Flavia Cristina da Silva

    2004-06-15

    The quality of the treatment in radiotherapy depends on the necessary knowledge of the liberated dose in the tumor and of several other physical parameters and dosimetric that characterize the profile of the radiation field. Worrying about the reliability of some commercial equipment that aim at determining the main parameters of a radiation field in a practical way for daily checks in an institution with radiotherapy service, in this work a study of the performance of the quality assurance system, QC6-Plus manufactured by PTW-Freiburg for daily checks, was developed, in order to assure the use of this equipment with larger reliability level in the routine of quality assurance of the hospitals as well as to make possible its use in the Program of Regulatory Inspections of the Services of Radiotherapy of the Country accomplished by IRD/CNEN. The found results indicate that the system QC6-Plus is perfectly adapted and practical for relative measures of daily and weekly control of the main parameters of clinical beans in agreement with reference values recommended in TECDOC 1151. However for measurements of absolute dose it should not be used because, for beams of electrons the system does not present the necessary characteristics to execute this measure type in agreement with the reference protocol, TRS 398, and for photons of energy 15 MV presented a deviation in relation to the conventional method of absolute dosimetry of 7,7%, that it is a lot above the expected in agreement with TRS 398. (author)

  9. An introduction to absorbent dressings.

    Science.gov (United States)

    Jones, Menna Lloyd

    2014-12-01

    Exudate bathes the wound bed with a serous fluid that contains essential components that promote wound healing. However, excess exudate is often seen as a challenge for clinicians. Absorbent dressings are often used to aid in the management of exudate, with the aim of providing a moist but unmacerated environment. With so many different types of absorbent dressings available today-alongside making a holistic assessment-it is essential that clinicians also have the knowledge and skill to select the most appropriate absorbent dressing for a given patient.

  10. Spontaneous emission and absorber theory

    Science.gov (United States)

    Pegg, David T.

    1997-01-01

    One of the long term interests of George Series was the construction of a theory of spontaneous emission which does not involve field quantisation. His approach was written in terms of atomic operators only and he drew a parallel with the Wheeler-Feynman absorber theory of radiation. By making a particular extra postulate, he was able to obtain the correct spontaneous emission rate and the Lamb shift reasonably simply and directly. An examination of his approach indicates that this postulate is physically reasonable and the need for it arises because quantisation in his theory occurs after the response of the absorber has been accounted for by means of the radiative reaction field. We review briefly an alternative absorber theory approach to spontaneous emission based on the direct action between the emitting atom and a quantised absorber, and outline some applications to more recent effects of interest in quantum optics.

  11. Broadband fast semiconductor saturable absorber.

    Science.gov (United States)

    Jacobovitz-Veselka, G R; Kellerm, U; Asom, T

    1992-12-15

    Kerr lens mode-locked (KLM) solid-state lasers are typically not self-starting. We address this problem by introducing a broadband semiconductor saturable absorber that could be used as a tunable, all-solid-state, passive starting mechanism. We extend the wavelength tunability of a semiconductor saturable absorber to more than 100 nm using a band-gap-engineered low-temperature molecular-beam-epitaxy (MBE)-grown bulk AlGaAs semiconductor saturable absorber in which the absorption edge of the saturable absorber has been artificially broadened by continuously reducing the Al concentration during the MBE growth. We demonstrate its tunability and its feasibility as a starting mechanism for KLM with a picosecond resonant passive mode-locked Ti:sapphire laser. The extension to femtosecond KLM lasers has been discussed previously.

  12. Guided tissue regeneration. Absorbable barriers.

    Science.gov (United States)

    Wang, H L; MacNeil, R L

    1998-07-01

    Over the past 15 years, techniques aimed at regeneration of lost periodontal tissue have become widely used and accepted in clinical practice. Among these techniques are those which use the principles of guided tissue regeneration (GTR), wherein barriers (i.e., membranes) are used to control cell and tissue repopulation of the periodontal wound. A variety of non-absorbable and absorbable barriers have been developed and used for this purpose, with a trend in recent years toward increased use of absorbable GTR materials. This article describes the evolution of absorbable barrier materials and overview materials available for clinical use today. In addition, advantages and disadvantages of these materials are discussed, as well as possible new developments in barrier-based GTR therapy.

  13. Test Facility for Volumetric Absorber

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, M.; Dibowski, G.; Pfander, M.; Sack, J. P.; Schwarzbozl, P.; Ulmer, S.

    2006-07-01

    Long-time testing of volumetric absorber modules is an inevitable measure to gain the experience and reliability required for the commercialization of the open volumetric receiver technology. While solar tower test facilities are necessary for performance measurements of complete volumetric receivers, the long-term stability of individual components can be tested in less expensive test setups. For the qualification of the aging effects of operating cycles on single elements of new absorber materials and designs, a test facility was developed and constructed in the framework of the KOSMOSOL project. In order to provide the concentrated solar radiation level, the absorber test facility is integrated into a parabolic dish system at the Plataforma Solar de Almeria (PSA) in Spain. Several new designs of ceramic absorbers were developed and tested during the last months. (Author)

  14. Mushroom plasmonic metamaterial infrared absorbers

    Science.gov (United States)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  15. Carbon Absorber Retrofit Equipment (CARE)

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Eric [Neumann Systems Group, Incorporated, Colorado Springs, CO (United States)

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  16. Mushroom plasmonic metamaterial infrared absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Shinpei, E-mail: Ogawa.Shimpei@eb.MitsubishiElectric.co.jp; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji [Advanced Technology R and D Center, Mitsubishi Electric Corporation, 8-1-1 Tsukaguchi-Honmachi, Amagasaki, Hyogo 661-8661 (Japan); Kimata, Masafumi [College of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577 (Japan)

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  17. Study of an electroacoustic absorber

    OpenAIRE

    Rodríguez de Antonio, Javier

    2008-01-01

    El problema de la atenuación del ruido de baja frecuencia todavía persiste pese a que ha sido ampliamente estudiado. Las técnicas para absorber ruido de alta frecuencia (superior a 500 Hz), como son los materiales porosos, resonadores de Helmholtz o espumas no ofrecen resultados aceptables a bajas frecuencias. Serían necesarios volúmenes impracticables de materiales porosos para intentar absorber frecuencias menores a 500 Hz, y lo mismo ocurre con los resonadores de Helmholtz. Esta ineficacia...

  18. Waveform-dependent absorbing metasurfaces

    CERN Document Server

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  19. Irradiation dose determination below room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Bernal, S. E-mail: ramos@nuclecu.unam.mx; Cruz, E.; Negron-Mendoza, A.; Bustos, E

    2002-03-01

    The measurements presented were undertaken to provide quantitative information on the low temperature irradiation of thermoluminiscence phosphors. The crystals used were (a) LiF co-doped with Mg, Cu and P, and (b) CaSO{sub 4} doped with Dy. The absorbed dose values in the interval studied showed a linear behavior at low doses and low temperature. The aim of this work is to test if these crystals can be used to measure the dose absorbed by solids at low temperature.

  20. Radiation dose estimates for radiopharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Stabin, M.G.; Stubbs, J.B.; Toohey, R.E. [Oak Ridge Inst. of Science and Education, TN (United States). Radiation Internal Dose Information Center

    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.

  1. Oil and fat absorbing polymers

    Science.gov (United States)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  2. The Clinical Research on Prevention Effects of Uterine Cavity Absorbed Biological Antiblocking Membrane Implantation plus Large Dose Estrogenic Administration plus Imitable Bioelectricity Stimulation Therapy for Uterine CavityAdhesion after TCRA%宫腔粘连分离术后宫腔放置可吸生物防粘连膜+大剂量雌激素+仿生物电疗预防再次粘连的临床研究

    Institute of Scientific and Technical Information of China (English)

    李艳虹; 梁晓斯; 林东红

    2016-01-01

    目的:探讨生物防粘连膜宫腔放置联合大剂量雌激素治疗,再给予仿生物电刺激治疗对宫腔粘连分离术后的再粘连防治的临床疗效。方法:选取2014年2月-2016年2月本院收治的经TCRA成功分离的中、重度宫腔粘连患者48例作为研究对象,随机分为观察组25例和对照组23例。观察组给予防粘连膜宫腔放置联合大剂量雌激素治疗,再给予仿生物电治疗,对照组则给予防粘连膜宫腔放置联合大剂量雌激素治疗,两组均以30 d为1个疗程,共进行3个疗程,B超检查子宫内膜修复程度。结果:治疗2个疗程后,两组子宫内膜均较治疗前增厚,且观察组优于对照组,比较差异均有统计学意义(P<0.05);观察组治疗总有效率为92.00%,明显高于对照组的56.52%,比较差异有统计学意义(P<0.05)。结论:防粘连膜宫腔放置联合大剂量雌激素治疗,再给予仿生物电刺激疗法能够有效防治宫腔粘连分离术后的再粘连。%Objective:To discuss the clinical effects of uterine cavity absorbed biological antiblocking membrane implantation plus large dose estrogenic administration plus imitable bioelectricity stimulation therapy for uterine cavity adhesion after TCRA.Method:From February 2014 to February 2016,48 cases of successfully separated by TCRA middle and severe uterine cavity adhesion in our hospital were selected as the research objects, they were randomly divided into the observation group of 25 cases and the control group of 23 cases.The observation group was given absorbed biological antiblocking membrane implantation plus large dose estrogenic administration plus imitable bioelectricity stimulation therapy,the control group was given absorbed biological antiblocking membrane implantation plus large dose estrogenic administration,two groups were treated with 30 d for 1 treatment course,a total of 3 courses,the degree of endometrial repair was inspected

  3. Insight into magnetorheological shock absorbers

    CERN Document Server

    Gołdasz, Janusz

    2015-01-01

    This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston.

  4. Optimum thickness of Mossbauer absorber

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a function of the thickness, and then fitting Qexp by its theoretical expression gives fa value. At last the dopt value is deduced from a maximum on the fitted curve. In such a way, thicknesses of six specimens with quadrupole or magnetic hyperfine splitting were optimized.

  5. Plasmonic titanium nitride nanostructures for perfect absorbers

    DEFF Research Database (Denmark)

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  6. Remarks on Wheeler-Feynman absorber theory

    OpenAIRE

    Gründler, Gerold

    2014-01-01

    The derivation of absorber theory is outlined in very detail. Absorber theory is based on classical action-at-a-distance electrodynamics, but it deviates from that theory at a crucial point. It is shown that (a) absorber theory cannot achieve any of it's essential results without this deviation, and that (b) this deviation restricts the application range of absorber theory to stationary radiation processes. Furthermore an error which crept into Wheeler's and Feynman's interpretation of their ...

  7. Synchrotron radiation absorber for high density loads

    Science.gov (United States)

    Anashin, V. V.; Kuzminych, V. S.; Trakhtenberg, E. M.; Zholents, A. A.

    1991-10-01

    A design of a special synchrotron radiation absorber for the storage ring VEPP-4M is presented. The density of the synchrotron radiation power on the absorber surface is up to 500 W/mm 2. The absorber is made from a beryllium plate, brazed inside to the copper vacuum chamber, which is intensively water-cooled from outside.

  8. Porcelain enamel neutron absorbing material

    Science.gov (United States)

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  9. Carbon dioxide absorbents for rebreather diving.

    Science.gov (United States)

    Pennefather, John

    2016-09-01

    Firstly I would like to thank SPUMS members for making me a Life Member of SPUMS; I was surprised and greatly honoured by the award. I also want to confirm and expand on the findings on carbon dioxide absorbents reported by David Harvey et al. For about 35 years, I was the main player in deciding which absorbent went into Australian Navy and Army diving sets. On several occasions, suppliers of absorbents to the anaesthesia market tried to supply the Australian military market. On no occasion did they provide absorbent that came close to the minimum absorbent capacity required, generally being 30-40% less efficient than diving-grade absorbents. Because I regard lives as being more important than any likely dollar saving, the best absorbent was always selected unless two suppliers provided samples with the same absorbent capacity. On almost every occasion, there was a clear winner and cost was never considered. I suggest the same argument for the best absorbent should be used by members and their friends who dive using rebreather sets. I make this point because of my findings on a set that was brought to me after the death of its owner. The absorbent was not the type or grain size recommended by the manufacturer of the set and did not resemble any of the diving grade absorbents I knew of. I suspected by its appearance that it was anaesthetic grade absorbent. When I tested the set, the absorbent system failed very quickly so it is likely that carbon dioxide toxicity contributed to his death. The death was not the subject of an inquest and I have no knowledge of how the man obtained the absorbent. Possibly there was someone from an operating theatre staff who unintentionally caused their friend's death by supplying him with 'borrowed absorbent'. I make this point as I would like to discourage members from making a similar error.

  10. Remarks on Wheeler-Feynman absorber theory

    CERN Document Server

    Gründler, Gerold

    2015-01-01

    The derivation of absorber theory is outlined in very detail. Absorber theory is based on classical action-at-a-distance electrodynamics, but it deviates from that theory at a crucial point. It is shown that (a) absorber theory cannot achieve any of it's essential results without this deviation, and that (b) this deviation restricts the application range of absorber theory to stationary radiation processes. Furthermore an error which crept into Wheeler's and Feynman's interpretation of their equation (19) is pointed out. These shortcomings can probably be eliminated by a quantum-theoretical formulation of absorber theory.

  11. A polarization-independent broadband terahertz absorber

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Cheng; Zang, XiaoFei, E-mail: xfzang@usst.edu.cn, E-mail: ymzhu@usst.edu.cn; Wang, YiQiao; Chen, Lin; Cai, Bin; Zhu, YiMing, E-mail: xfzang@usst.edu.cn, E-mail: ymzhu@usst.edu.cn [Shanghai Key Laboratory of Modern Optical System and Engineering Research Center of Optical Instrument and System, Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093 (China)

    2014-07-21

    A highly efficient broadband terahertz absorber is designed, fabricated, and experimentally as well as theoretically evaluated. The absorber comprises a heavily doped silicon substrate and a well-designed two-dimensional grating. Due to the destructive interference of waves and diffraction, the absorber can achieve over 95% absorption in a broad frequency range from 1 to 2 THz and for angles of incidence from 0° to 60°. Such a terahertz absorber is also polarization-independent due to its symmetrical structure. This omnidirectional and broadband absorber have potential applications in anti-reflection coatings, imaging systems, and so on.

  12. Multi-channel coherent perfect absorbers

    KAUST Repository

    Bai, Ping

    2016-05-18

    The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

  13. Dose reader of dosimetric foil; Czytnik dawki folii dozymetrycznej

    Energy Technology Data Exchange (ETDEWEB)

    Machaj, B.; Strzalkowski, J.; Smolko, K.

    1997-12-31

    Read out the absorbance of a dosimetric foil is accomplished by two beam spectrophotometer. Such a solution makes possible the compensation of light source instabilities and ensures higher stability of the dose reader. The error of absorbance measurement caused by the instabilities does not exceed 0.0004 A. (author). 3 refs, 3 figs.

  14. Numerical simulations of quasar absorbers

    CERN Document Server

    Theuns, T

    2005-01-01

    The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the matter-power spectrum, reionisation history, ionising background and the nature of the dark matter. The spectra also contain metal lines, which can be used to constrain the star formation history and the feedback processes acting in large and small galaxies. Simulations have been instrumental in investigating to what extent these parameters can be unambiguously constrained with current and future data. This paper is meant as an introduction to this subject, and reviews techniques and methods for simulating the intergalactic medium.

  15. Warm Absorbers in Active Galactic Nuclei

    CERN Document Server

    Komossa, S

    2000-01-01

    We first provide a review of the properties of warm absorbers concentrating on what we have learned from ROSAT and ASCA. This includes dusty and dust-free warm absorbers, non-X-ray emission and absorption features of warm absorbers, and the possible warm absorber interpretation of the peculiar 1.1 keV features. We then discuss facets of warm absorbers by a more detailed investigation of individual objects: In a first part, we discuss several candidates for dusty warm absorbers. In a second part, we review and extend our earlier study of a possible relation between warm absorber and CLR in NGC 4051, and confirm that both components are of different origin (the observed coronal lines are underpredicted by the models, the warm absorber is too highly ionized). We then suggest that a potential overprediction of these lines in more lowly ionized absorbers can be avoided if these warm absorbers are dusty. In a third part, we present first results of an analysis of a deep ROSAT PSPC observation of the quasar MR2251-1...

  16. Conformal radiotherapy made easy through gravity oriented absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Proimos, B.S. [Patras Univ. (Greece). Dept. of Medical Physics

    1995-12-01

    In the 50`s and the 60`s simple techniques modulating the beam intensity in synchronism with the rotation, either of the vertical patient or of the machine around the horizontal patient were developed. An absorber, which is similar in shape to a vital organ, intercepts the beam, casting its protective `shade` over the organ, for all positions of rotation. In this way, the organ is protected during the irradiation time. On any transverse cross, any point outside of the organ`s cross-section is protected for only a fraction of T, which is decreasing with the distance of that point from the organ. Consequently, the dose to the protected organ is smaller than (a) the dose it would absorb without protection (b) the dose to the surrounding (less vital) healthy tissue and (c), the dose to the neighbouring tumour. Consider a plane perpendicular to the principal plane and passing through the source. It cuts the organ and its protector in two cross-sections, which remain always homiotheta, with centre of homiothesis the source. In this way, the protector`s cross-section is projected by the beam on the organ`s cross-section for all positions of rotation. The larger the cross-section of the organ and the smaller the required protection, the smaller must be the attenuation coefficient of the material the protector is made of. The dose distributions in a series of actual cases, such as head tumours with eyes protection, neck or chest tumours with spinal cord protection, cervix tumours with rectum and bladder protection, are discussed. In most cases, if the vital organs are not overprotected, the 90% or 80% isodose surface fits to or conforms with the surface of the Planning Target Volume (PTV) no matter how irregular (convex and concave) it is.

  17. Effects of dose and dose protraction on embryotoxicity of 14.1 MeV neutron irradiation in rats

    Energy Technology Data Exchange (ETDEWEB)

    Beckman, D.A.; Buck, S.J. [Alfred I. duPont Institute, Wilmington, DE (United States)]|[Thomas Jefferson Univ., Philadelphia, PA (United States); Solomon, H.M. [SmithKline and Beecham Pharmaceuticals, King of Prussia, PA (United States); Gorson, R.O. [Thomas Jefferson Univ., Philadelphia, PA (United States); Mills, R.E. [Brookhaven National Lab., Upton, NY (United States); Brent, R.L. [Alfred I. duPont Institute, Wilmington, DE (United States)]|[Thomas Jefferson Univ., Philadelphia, PA (United States)

    1994-06-01

    The embryotoxic effects of neutron radiation on rodent embryos are documented, but there is disagreement about the dose-response relationship and the impact of protracting the dose. Pregnant rats were exposed to total absorbed doses of 0.15 to 1.50 Gy 14.1 MeV neutrons on day 9.5 after conception, coincident with the most sensitive stage of embryonic development for the induction of major congenital malformations. In general terms, the incidence of embryotoxic effects increased with increasing total absorbed dose. However, the dose-response relationship differed depending on the parameter of embryotoxicity chosen, namely, intrauterine death, malformations or very low body weight. In a second study, embryos were exposed to a single embryotoxic absorbed dose (0.75 Gy) administered at a range of dose rates, from 0.10 to 0.50 Gy/h. The results offer no evidence that protraction of this selected dose significantly increased or decreased the incidence or pattern of embryotoxicity of the neutron exposure used in this study. The results do not support the hypothesis of a linear dose-response relationship for the effects of prenatal neutron irradiation that contribute to embryotoxicity for total absorbed doses of 0.15 to 1.50 Gy. 23 refs., 8 tabs.

  18. Calculation of dose absorbed for the verification of the calibration curves UH-Density electronic relative obtained with various mannequins; Calculo de dosis absorbida para la verificacion de las curvas de calibracion UH-Densidad electronica relativa obtenidas con distintos maniquies

    Energy Technology Data Exchange (ETDEWEB)

    Perez Alvarez, M. E.; Sena Espinel, E. de; Delgado Aparicio, J. M.; Martin Rincon, C.; Garcia Repiso, S.; Ramos Pacho, J. A.; Verde Velasco, J. M.; Gomez Gonzalez, N.; Cons Perez, N.; Saez Beltran, M.

    2013-07-01

    In order to discern with what calibration curve is obtained a more accurate dosimetry distribution, dose measurements are carried out on the treatment unit and the values found are evaluated. (Author)

  19. Multiband Negative Permittivity Metamaterials and Absorbers

    Directory of Open Access Journals (Sweden)

    Yiran Tian

    2013-01-01

    Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

  20. Multiobjective Topology Optimization of Energy Absorbing Materials

    Science.gov (United States)

    2015-08-01

    125–143 DOI 10.1007/s00158-014-1117-8 RESEARCH PAPER Multiobjective topology optimization of energy absorbing materials Raymond A. Wildman · George A...recent developments. J Multiscale Model 3(4):1–42 Qiao P, Yang M, Bobaru F (2008) Impact mechanics and high-energy absorbing materials: review . J Aerosp...ARL-RP-0533 ● AUG 2015 US Army Research Laboratory Multiobjective Topology Optimization of Energy Absorbing Materials by

  1. A Six-Fold Symmetric Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Humberto Fernández Álvarez

    2015-04-01

    Full Text Available A novel microwave metamaterial absorber design is introduced along with its manufacturing and characterization. Significant results considering both bandwidth and angular stability are achieved. Parametric analysis and simplified equivalent circuit are provided to give an insight on the key elements influencing the absorber performance. In addition, the constitutive parameters of the effective medium model are obtained and related to the absorber resonant behavior. Moreover, a new thinner and more flexible absorber version, preserving broad bandwidth and angular insensitive performance, is simulated, and an 8 × 8 unit-cells prototype is manufactured and measured for a limited angular margin in an anechoic chamber.

  2. Tuned mass absorber on a flexible structure

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    2014-01-01

    The classic design of a tuned mass absorber is based on a simple two-mass analogy in which the tuned mass is connected to the structural mass with a spring and a viscous damper. In a flexible multi-degree-of-freedom structure the tuned mass absorber is typically introduced to provide damping...... of a specific mode. The motion of the point of attachment of the tuned mass absorber to the structure has not only a contribution from the targeted mode, but also a background contribution from other non-resonant modes. Similarly, the force provided by the tuned mass absorber is distributed between the targeted...

  3. Absorbent product and articles made therefrom

    Science.gov (United States)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  4. Metamaterial absorber with random dendritic cells

    Science.gov (United States)

    Zhu, Weiren; Zhao, Xiaopeng

    2010-05-01

    The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

  5. Polystyrene calorimeter for electron beam dose measurements

    DEFF Research Database (Denmark)

    Miller, A.

    1995-01-01

    Calorimeters from polystrene have been constructed for dose measurement at 4-10 MeV electron accelerators. These calorimeters have been used successfully for a few years, and polystyrene calorimeters for use at energies down to 1 MeV and being tested. Advantage of polystyrene as the absorbing...

  6. Dose calculation using a numerical method based on Haar wavelets integration

    Energy Technology Data Exchange (ETDEWEB)

    Belkadhi, K., E-mail: khaled.belkadhi@ult-tunisie.com [Unité de Recherche de Physique Nucléaire et des Hautes Énergies, Faculté des Sciences de Tunis, Université Tunis El-Manar (Tunisia); Manai, K. [Unité de Recherche de Physique Nucléaire et des Hautes Énergies, Faculté des Sciences de Tunis, Université Tunis El-Manar (Tunisia); College of Science and Arts, University of Bisha, Bisha (Saudi Arabia)

    2016-03-11

    This paper deals with the calculation of the absorbed dose in an irradiation cell of gamma rays. Direct measurement and simulation have shown that they are expensive and time consuming. An alternative to these two operations is numerical methods, a quick and efficient way can furnish an estimation of the absorbed dose by giving an approximation of the photon flux at a specific point of space. To validate the numerical integration method based on the Haar wavelet for absorbed dose estimation, a study with many configurations was performed. The obtained results with the Haar wavelet method showed a very good agreement with the simulation highlighting good efficacy and acceptable accuracy. - Highlights: • A numerical integration method using Haar wavelets is detailed. • Absorbed dose is estimated with Haar wavelets method. • Calculated absorbed dose using Haar wavelets and Monte Carlo simulation using Geant4 are compared.

  7. 21 CFR 872.6050 - Saliva absorber.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  8. An ultrathin dual-band metamaterial absorber

    Science.gov (United States)

    Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun; Zhang, Binzhen

    2016-10-01

    The design and preparation of an ultrathin dual-band metamaterial absorber whose resonant frequency located at radar wave (20 GHz-60 GHz) is presented in this paper. The absorber is composed of a 2-D periodic sandwich featured with two concentric annuluses. The influence on the absorber's performance produced by resonant cell's structure size and material parameters was numerically simulated and analyzed based on the standard full wave finite integration technology in CST. Laser ablation process was adopted to prepare the designed absorber on epoxy resin board coated with on double plane of copper with a thickness that is 1/30 and 1/50 of the resonant wavelength at a resonant frequency of 30.51 GHz and 48.15 GHz. The full width at half maximum (FWHM) reached 2.2 GHz and 2.35 GHz and the peak of the absorptance reached 99.977%. The ultrathin absorber is nearly omnidirectional for all polarizations. The test results of prepared sample testify the designed absorber's excellent absorbing performance forcefully. The absorber expands inspirations of radar stealth in military domain due to its flexible design, cost-effective and other outstanding properties.

  9. Comments on liquid hydrogen absorbers for MICE

    Energy Technology Data Exchange (ETDEWEB)

    Green, Michael A.

    2003-02-01

    This report describes the heat transfer problems associatedwith a liquid hydrogen absorber for the MICE experiment. This reportdescribes a technique for modeling heat transfer from the outside world,to the abosrber case and in its vacuum vessel, to the hydrogen and theninto helium gas at 14 K. Also presented are the equation for freeconvection cooling of the liquid hydrogen in the absorber.

  10. Doses in sensitive organs during prostate treatment with a 60Co unit.

    Science.gov (United States)

    Vega-Carrillo, H R; Navarro Becerra, J A; Pérez Arrieta, M L; Pérez-Landeros, L H

    2014-01-01

    Using thermoluminiscent dosimeters the absorbed dose in the bladder, rectum and thyroid have been evaluated when 200 cGy was applied to the prostate. The treatment was applied with a (60)Co unit. A water phantom was built and thermoluminiscent dosimeters were located in the position where the prostate, bladder, rectum and thyroid are located. The therapeutic beam was applied in 4 irradiations at 0, 90, 180 and 270° with the prostate at the isocenter. The TLDs readouts were used to evaluate the absorbed dose in each organ. The absorbed doses were used to estimate the effective doses and the probability of developing secondary malignacies in thyroid, rectum and bladder.

  11. Practical absorption limits of MPP absorber

    Institute of Scientific and Technical Information of China (English)

    MAA Dah-You

    2006-01-01

    The construction and properties of microperforated panel (MPP) absorber are discussed. The absorption limit of the absorber had been shown that low values of the perforate constant k = d(f/10)1/2 and the orifice diameter d (in mm) are essential for MPP to have high absorption in wide frequency band. To find the exact limits, take 1 for k as a start, because both specific resistance and high absorption require k around one. And the orifice diameter d is chosen as 0.1 mm, so that the peak absorption coefficient (resonance absorption) is at 1000 Hz,and high sound frequency may be in the absorption region. Is it possible for a single layer of such an MPP to cover the whole absorption region required in practice? The half-absorption limit is not a good criterion, because low absorption comes in also in some cases. The 0.5 absorption coefficient limit is suggested for practical region, as a standard for comparison. Absorption curves were drawn for different load resistances, of absorption coefficients versus frequency.Ordinary MPP absorber absorbs in slightly over two octaves, and the new absorber with r = 1 (specific resistance equal to the characteristic impedance in air)is slightly better than these, 2.5 octaves. The new absorbers with r > 1, are much better than these, and some satisfies high absorption in broad frequency range. Realization of these will mean great progress of MPP absorbers.

  12. Dose reduction factors from a radioactive cloud for large buildings

    Energy Technology Data Exchange (ETDEWEB)

    Grand, J. le; Roux, Y.; Patau, J.P.

    1986-01-01

    A set of complex and accurate computer codes has been established to determine the transport of photons emitted from a radioactive cloud through various media. The geometrical and physical description of large buildings with various numbers of floors and rooms can be done by the user. The codes can calculate, in any room or apartment, the characteristics of the photon fields (photon flux, energy flux and distribution, direction distribution) and whole-body absorbed dose rates in a phantom standing or lying on the floor. The dose reduction factor is then the quotient of the mean absorbed dose rate in the apartment to the absorbed dose rate in the phantom standing on the ground outdoors. Applications to several modern multistorey buildings are presented. The results show the influence of various parameters such as density and composition of building materials, the fraction of the external building surface containing apertures and initial photon energy.

  13. Design and application of functional absorbers

    Institute of Scientific and Technical Information of China (English)

    WANG Jiqing

    2004-01-01

    This paper gives an overview of the research at Institute of Acoustics, Tongji University, on functional absorbers and experience acquired in practical applications over the past three decades. Experiments and analysis of the absorption characteristics of three different geometrical forms of functional absorbers, i.e., panels, cubes and tubes, were conducted with different arrangements. The resulting esthetical effects are illustrated with pictures. Several non-fiber materials are used to compose functional absorbers with advantages both in acoustic properties and in architectural features. Cost effectiveness analysis is also given in order to provide design guidelines.

  14. Absorbed Energy in Ship Collisions and Grounding

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    is that the absorbed energy does not depend on the arrangement of the structure, the material properties, and the damage mode.The purpose of the present paper is to establish a new simple relation between the absorbed energy and the destroyed material volume, which can be used as a design tool for analysis of ship......Minorsky's well-known empirical formula, which relates the absorbed energy to the destroyed material volume, has been widely used in analyses of high energy collision and grounding accidents for nearly 40 years. The advantage of the method is its apparent simplcity. Obviously, its drawback...

  15. Graphene and Graphene Metamaterials for Terahertz Absorbers

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows...... for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present our recent experimental results on the graphene absorbers characterization....

  16. Dose estimative in operators during petroleum wells logging with nuclear wireless probes through computer modelling; Estimativa da dose em operadores durante procedimentos de perfilagem de pocos de petroleo com sondas wireless nucleares atraves de modelagem computacional

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Edmilson Monteiro de; Silva, Ademir Xavier da; Lopes, Ricardo T., E-mail: emonteiro@nuclear.ufrj.b, E-mail: ademir@nuclear.ufrj.b, E-mail: ricardo@lin.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Lima, Inaya C.B., E-mail: inaya@lin.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Instituto Politecnico do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil); Correa, Samanda Cristine Arruda, E-mail: scorrea@cnen.gov.b [Comissao Nacional de Energia Nuclear (DIAPI/CGMI/CNEN), Rio de Janeiro, RJ (Brazil); Rocha, Paula L.F., E-mail: ferrucio@acd.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ)., RJ (Brazil). Dept. de Geologia

    2011-10-26

    This paper evaluates the absorbed dose and the effective dose on operators during the petroleum well logging with nuclear wireless that uses gamma radiation sources. To obtain the data, a typical scenery of a logging procedure will be simulated with MCNPX Monte Carlo code. The simulated logging probe was the Density Gamma Probe - TRISOND produced by Robertson Geolloging. The absorbed dose values were estimated through the anthropomorphic simulator in male voxel MAX. The effective dose values were obtained using the ICRP 103

  17. Specific absorbed fraction of X-ray in tissues from human organs

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, H.C. [Department of Physics, Government College for Women, Karnalaka (India)

    2013-07-01

    Full text: X- rays are widely used in medical imaging and radiation therapy. The user of radioisotopes must have knowledge about how radiation interacts with matter, especially with the human body, because when photons enter the medium/body, they degrade their energy and build up in the medium, giving rise to secondary radiation. Calculations of the energy absorbed in a medium include not only the contribution of the uncollided photons from the source, but must also include the contributions from collided and secondary photons. In practice, this is done by multiplying the contribution of the uncollided photons by the energy absorption buildup factor. An accurate absorbed dose calculation needs specific absorbed fraction of energy. Geometric progression (GP) fitting method has been used to compute energy absorption build-up factor of Human organs such as brain, breast, eye lens, GI track, heart, kidney, liver, lung, lymph, ovary, pancreas, testis and skeleton-femur. The computed absorption build-up factor is used to estimate specific absorbed fraction of energy. The thickness of the medium up to 10mm and with penetration depth up to 40 mean free paths considered. The dependence of specific absorbed fraction of energy on incident photon energy, penetration and the thickness of the medium have also been studied. The specific absorbed fraction of energy increases up to the E{sub pe} and then decreases. Here E{sub pe} is the energy value at which the photo electric interaction coefficients matches with Compton interaction coefficients for a given value of effective atomic number (Z{sub eff}). The variation of specific absorbed fractions with energy is due to dominance of photoelectric absorption in the lower end and dominance of pair production in the higher photon energy region. In the lower energy end photoelectric absorption is dominant photon interaction process; hence specific absorbed fractions values minimum. As the energy of incident photon increases, Compton

  18. ABSORBABLE IRON IN BREAD: PROCEDURES OF ITS AUGMENTATION

    Directory of Open Access Journals (Sweden)

    M SABZEVARY

    2001-12-01

    Full Text Available Introduction: As many as 35 percent of the world population suffer from some degree of iron deficiency anemia. According to recent reports published by WHO and ICN (International Congress of Nutrition 20-40 percent of women are suffering from iron deficiency. Iron deficiency anemia is caused by lack of intake of the necessary doses of Fe+2 called Heme. The recommended intake dose is 10-17 mg Fe + 2/day. In Iran, bread is the main source of daily iron intake. However, the iron content of bread is Fe+3 which is not absorbable. The objectives of this study is to determine the levels of absorbable iron (Fe + 2 in two common types of Iranian bread and identify the means of raising these to an adequate levels.
    Methods: Random sampling method together with the normal distribution curve was employed in testing 120 samples of flour and bread. Quantification was carried out on each sample in duplicate using spectrophotometer at 510 mu, micrometer wave length. The effect of three organic acids (lactic ascorbic and acetic acid converting of Fe+3 to Fe + 2 was investigated. Two groups of bread was tested. One group was baked in tratitional oven (Noon-e-Tanoori and the second group through the common Iranian hot rotating iron plate baking machine (Noon-e-Machini.
    Results: Our results showed that the amount of absorbable Fe+2 in breads baked in rotatory oven (Noon-e-Tanoori is 0.8 ± 0.32 mg and the amount of unabsorbable Fe+3 in dried bread is 2.34 ± 0.25 mg/100 gm while the amount of absorbable Fe + 2 baked in traditional ovens is only 0.3±0.11 mg versus of unabsorbable Fe  + 3 1.9±0.13 mg/100 gm of dried bread. Meanwhile it was found that lactic and ascorbic acids can convert Fe+3 to Fe+2. Therefore, addition of one of these two acids to bread can catalyze conversion of unabsorbable Fe+3 to absorbable Fe + 2.
    Discussion: On the average an Iranian consumes 370 gm of

  19. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

  20. Space Compatible Radar Absorbing Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 1 project shall investigate novel radar absorbing materials (RAM) for use in space or simulated space environments. These materials are lightweight...

  1. Semiconductor saturable absorbers for ultrafast THz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths.......We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths....

  2. Taming electromagnetic metamaterials for isotropic perfect absorbers

    Directory of Open Access Journals (Sweden)

    Doan Tung Anh

    2015-07-01

    Full Text Available Conventional metamaterial absorbers, which consist of a dielectric spacer sandwiched between metamaterial resonators and a metallic ground plane, have been inherently anisotropic. In this paper, we present an alternative approach for isotropic perfect absorbers using symmetric metamaterial structures. We show that by systematically manipulating the electrically and magnetically induced losses, one can achieve a desired absorption without breaking the structural homogeneity. Finite integration simulations and standard retrieval method are performed to elaborate on our idea.

  3. Graphene and Graphene Metamaterials for Terahertz Absorbers

    OpenAIRE

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim; Bøggild, Peter

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present...

  4. Absorbing Boundary Conditions for Hyperbolic Systems

    Institute of Scientific and Technical Information of China (English)

    Matthias Ehrhardt

    2010-01-01

    This paper deals with absorbing boundary conditions for hyperbolic systems in one and two space dimensions. We prove the strict well-posedness of the resulting initial boundary value problem in 1D. Afterwards we establish the GKS-stability of the corresponding Lax-Wendroff-type finite difference scheme. Hereby, we have to extend the classical proofs, since the (discretized) absorbing boundary conditions do not fit the standard form of boundary conditions for hyperbolic systems.

  5. Accredited dose measurements for validation of radiation sterilized products

    DEFF Research Database (Denmark)

    Miller, A.

    1993-01-01

    The activities and services of the accredited Risø High Dose Reference Laboratory are described. The laboratory operates according to the European standard EN 45001 regarding Operation of Testing Laboratories, and it fulfills the requirements of being able to deliver traceable dose measurements f...... of the dosimetric parameters of an irradiation facility. 5. 5. Measurement of absorbed dose distribution in irradiated products. The paper describes these services and the procedures necessary for their execution....

  6. Perfect terahertz absorber using fishnet based metafilm

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul Kalam [Los Alamos National Laboratory; Shchegolkov, Dmitry Yu [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; Smirnova, E I [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  7. Advances in micro-perforated panel absorbers

    Institute of Scientific and Technical Information of China (English)

    LIU Ke; TIAN Jing; JIAO Fenglei; L(U) Yadong

    2006-01-01

    Theoretical and experimental investigations on the performance of micro-perforated-panel absorbers are reviewed in this paper. By reviewing recent research work, this paper reveals a relationship between the maximum absorption coefficient and the limit of the absorption frequency bandwidth. It has been demonstrated that the absorption frequency bandwidth can be extended up to 3 or 4 octaves as the diameters of the micro-holes decrease. This has become possible with the development of the technologies for manufacturing micro-perforated panels,such as laser drilling, powder metallurgy, welded meshing and electro-etching to form micrometer order holes. In this paper, absorption characteristics of such absorbers in random fields and in high sound intensity are discussed both theoretically and experimentally. A new absorbing structure based on micro-perforated-panel absorbers demonstrate experimentally high sound absorption capability. This review shows that the micro-perforated-panel absorber has potentials to be one of ideal absorbing materials in the 21st century.

  8. Adaptive Piezoelectric Absorber for Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Sven Herold

    2016-02-01

    Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

  9. A dose-effect correlation for radioiodine ablation in differentiated thyroid cancer

    Energy Technology Data Exchange (ETDEWEB)

    Flux, Glenn D.; Chittenden, Sarah J.; Buckley, Susan; Hindorf, Cecilia [Royal Marsden NHS Foundation Trust, Department of Physics, Sutton, Surrey (United Kingdom); Haq, Masud; Newbold, Kate; Harmer, Clive L. [Royal Marsden NHS Foundation Trust, Thyroid Unit, Sutton, Surrey (United Kingdom)

    2010-02-15

    The aim of this study was to determine the range of absorbed doses delivered to thyroid remnants, blood, and red marrow from fixed administrations of radioiodine and to ascertain whether the success of ablation is more dependent on these absorbed doses than on the administered activity. Twenty-three patients received 3,000 MBq radioiodine following near-total thyroidectomy. The maximum absorbed dose to remnants was calculated from subsequent single photon emission tomography scans. Absorbed doses delivered to blood and red marrow were calculated from blood samples and from whole-body retention measurements. The protein bound iodine (PBI) was also calculated. Maximum absorbed doses to thyroid remnants ranged from 7 to 570 Gy. Eighteen of the 23 patients had a successful ablation. A significant difference was seen between the absorbed doses delivered to thyroid remnants, blood, and red marrow for those patients that had a successful ablation compared to those with a failed ablation (p = 0.030, p = 0.043 and p = 0.048, respectively). The difference between the PBI values acquired at day 1 and day 6 were also indicative of response (p = 0.074). A successful ablation is strongly dependent on the absorbed dose to the thyroid remnant. Dosimetry-based personalized treatment can prevent both sub-optimal administrations, which entails further radioiodine therapy, and excessive administration of radioactivity, which increases the potential for radiation toxicity. (orig.)

  10. Megagray Dosimetry (or Monitoring of Very Large Radiation Doses)

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Uribe, R.M.; Miller, Arne

    1983-01-01

    A number of suitably calibrated plastic and dyed films and solid-state systems can provide mapping of very intense radiation fields with high spatial resolution and reasonable limits of uncertainty of absorbed dose assessment. Although most systems of this type suffer from rate dependence...... and temperature dependence of response when irradiated with charged particle beams at high dose rates, a few are stable, easily calibrated, and capable of faithful imaging of detailed dose profiles, even at doses up to 106 Gy and dose rates up to 108 Gy·s−1. Candidates include certain undyed plastic films (e...

  11. Organ dose and effective dose with the EOS scanner in spine deformity surgery

    DEFF Research Database (Denmark)

    Heide Pedersen, Peter; Eiskjær, Søren Peter; Petersen, Asger Greval

    2016-01-01

    leads to tissue damage. It has been documented in large cohort studies that radiographic imaging during childhood for spinal deformities eg. scoliosis, increases the lifetime risk of breast cancer. The EOS biplane x-ray imaging system (EOS Imaging S.A, Paris France) has been developed to produce high...... factors. These findings and image quality will be compared to previously reported findings in standard settings and to conventional digital x-ray(CR) Results: Our preliminary studies have shown a significant reduction in absorbed organ dose. In AP position we found a mean liver organ dose of 0.03m...... year old and an adolescent. Thermoluminiscent detectors are used to measure organ dose. A first time measurement with micro-dose settings in both AP and PA will be performed in addition to standard settings in AP and PA positions. Effective dose is calculated using mean organ doses and tissue weighting...

  12. Local skin and eye lens equivalent doses in interventional neuroradiology

    Energy Technology Data Exchange (ETDEWEB)

    Sandborg, Michael [Linkoeping University, Department of Radiological Sciences, Radiation Physics and Center for Medical Image Science and Visualisation (CMIV), Linkoeping (Sweden); Linkoeping University Hospital, Department of Medical Physics, Linkoeping (Sweden); Rossitti, Sandro [Linkoeping University Hospital, Department of Neurosurgery, Linkoeping (Sweden); Pettersson, Haakan [Linkoeping University Hospital, Department of Medical Physics, Linkoeping (Sweden)

    2010-03-15

    To assess patient skin and eye lens doses in interventional neuroradiology and to assess both stochastic and deterministic radiation risks. Kerma-area product (P{sub KA}) was recorded and skin doses measured using thermoluminescence dosimeters. Estimated dose at interventional reference point (IRP) was compared with measured absorbed doses. The average and maximum fluoroscopy times were 32 and 189 min for coiling and 40 and 144 min for embolisation. The average and maximum P{sub KA} for coiling were 121 and 436 Gy cm{sup 2}, respectively, and 189 and 677 Gy cm{sup 2} for embolisation. The average and maximum values of the measured maximum absorbed skin doses were 0.72 and 3.0 Sv, respectively, for coiling and 0.79 and 2.1 Sv for embolisation. Two out of the 52 patients received skin doses in excess of 2 Sv. The average and maximum doses to the eye lens (left eye) were 51 and 515 mSv (coiling) and 71 and 289 mSv (embolisation). The ratio between the measured dose and the dose at the IRP was 0.44 {+-} 0.18 mSv/mGy indicating that the dose displayed by the x-ray unit overestimates the maximum skin dose but is still a valuable indication of the dose. The risk of inducing skin erythema and lens cataract during our hospital procedures is therefore small. (orig.)

  13. National pattern for the realization of the unit of the dose speed absorbed in air for beta radiation. (Method: Ionometer, cavity of Bragg-Gray implemented in an extrapolation chamber with electrodes of variable separation, exposed to a field of beta radiation of {sup 90}Sr/{sup 90}Y); Patron Nacional para la realizacion de la unidad de la rapidez de dosis absorbida en aire para radiacion beta. (Metodo: Ionometrico, cavidad de Bragg-Gray implementada en una camara de extrapolacion con electrodos de separacion variable, expuesta a un campo de radiacion beta de {sup 90}Sr/{sup 90}Y)

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez R, M. T.; Morales P, J. R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2001-01-15

    From the year of 1987 the Department of Metrology of the ININ, in their Secondary Laboratory of Calibration Dosimetric, has a patron group of sources of radiation beta and an extrapolation chamber of electrodes of variable separation.Their objective is to carry out of the unit of the dose speed absorbed in air for radiation beta. It uses the ionometric method, cavity Bragg-Gray in the extrapolation chamber with which it counts. The services that offers are: i) it Calibration : Radioactive Fuentes of radiation beta, isotopes: {sup 90}Sr/{sup 90}Y; Ophthalmic applicators {sup 9}0{sup S}r/{sup 90}Y; Instruments for detection of beta radiation with to the radiological protection: Ionization chambers, Geiger-Muller, etc.; Personal Dosemeters. ii) Irradiation with beta radiation of materials to the investigation. (Author)

  14. Calibration of TLD-100 powder for energies of {sup 60} Co, {sup 137} Cs, {sup 192} Ir and RX of 250, 50 kV{sub p} in absorbed dose in water with dosimetric quality control purposes for brachytherapy of high dose rate; Calibracion de polvo TLD-100 para energias de {sup 60} Co, {sup 137} Cs, {sup 192} Ir y RX de 250, 50 kVp en dosis absorbida en agua con fines de control de calidad dosimetrico para braquiterapia de alta tasa de dosis

    Energy Technology Data Exchange (ETDEWEB)

    Loaiza C, S.P. [Programa de Maestria en Fisica Medica, Universidad Autonoma del Estado de Mexico, Paseo Tollocan S/N, esquina con Jesus Carranza, Colonia Moderna de la Cruz, 50180 Toluca, Edo. de Mexico (Mexico); Alvarez R, J.T. [Laboratorio Secundario de Calibracion Dosimetrica LSCD, Departamento de Metrologia, ININ, Carretera Federal Mexico Toluca S/N, La Marquesa, 52750 Ocoyoacac, Edo. de Mexico (Mexico)

    2006-07-01

    To help solve the traceability and quality control dosimetric problems for the users of {sup 192} Ir sources in the Mexican Republic, the Secondary Standard Dosimetric Laboratory at ININ to calibrated a batch of powder TLD- 100 (LiF: Mg,Ti) in terms of absorbed dose to water D{sub w} for the following radiation sources: {sup 60} Co, {sup 137C}s and RX 250 and 50 k Vp. Later on, the calibration is interpolated to obtain the {sup 192} Ir. The calibration radiation field is carried out with the following protocols: For the {sup 60} Co, IAEA TRS 398 protocol employing a secondary standard Farmer chamber PTW N30013, calibrated on D{sub w} at the NRC (Canada). For {sup 137} Cs the AAPM TG 43 protocol is used, in terms of air kerma strength S{sub k} determined by the air kerma K{sub a}, measured with a secondary standard chamber type thimble NE2611 traceable to the NIST (USA). For Rays X 250 and 50 k Vp, the protocol AAPM TG 61 using a tertiary standard Farmer chamber PTW 30001, with traceability to the LCIE (France) on air kerma K{sub a}. The calibration curves are built for the TLD response R{sub TLD} vs D{sub w}, they are fitted by means of a least squares fit technique with a second degree polynomial that corrects the supra linearity response. The curves are validated by the lack of fit test, and the Anderson Darling normality test. Later on, the sensibility factors are interpolated for the sources of {sup 192} Ir: Micro Selectron and Vari Source. Two capsules are sent to two hospitals to verify a nominal D{sub w} = 2 Gy, in the first one an underestimate of the D{sub w} is obtained, and in other one an overestimation is presented. Finally, the expanded uncertainty associated to D{sub w} and the F{sub s} are calculated. (Author)

  15. Warm Absorber Diagnostics of AGN Dynamics

    Science.gov (United States)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  16. Detecting and interpreting statistical lensing by absorbers

    CERN Document Server

    Ménard, B

    2004-01-01

    We propose a method for detecting gravitational magnification of distant sources, like quasars, due to absorber systems detected in their spectra. We first motivate the use of metal absorption lines rather than Lyman-alpha lines, then we show how to relate the observed moments of the source magnitude distribution to the mass distribution of absorbers. In order to illustrate the feasibility of the method, we use a simple model to estimate the amplitude of the effect expected for MgII absorption lines, and show that their lensing signal might already be detectable in large surveys like the SDSS. Our model suggests that quasars behind strong MgII absorbers are in average brightened by -0.05 to -0.2 magnitude due to magnification. One must therefore revisit the claim that, in magnitude limited surveys, quasars with strong absorbers tend to be missed due to extinction effects. In addition to constraining the mass of absorber systems, applying our method will allow for the quantification of this bias.

  17. Ultrathin flexible dual band terahertz absorber

    Science.gov (United States)

    Shan, Yan; Chen, Lin; Shi, Cheng; Cheng, Zhaoxiang; Zang, Xiaofei; Xu, Boqing; Zhu, Yiming

    2015-09-01

    We propose an ultrathin and flexible dual band absorber operated at terahertz frequencies based on metamaterial. The metamaterial structure consists of periodical split ring resonators with two asymmetric gaps and a metallic ground plane, separated by a thin-flexible dielectric spacer. Particularly, the dielectric spacer is a free-standing polyimide film with thickness of 25 μm, resulting in highly flexible for our absorber and making it promising for non-planar applications such as micro-bolometers and stealth aircraft. Experimental results show that the absorber has two resonant absorption frequencies (0.41 THz and 0.75 THz) with absorption rates 92.2% and 97.4%, respectively. The resonances at the absorption frequencies come from normal dipole resonance and high-order dipole resonance which is inaccessible in the symmetrical structure. Multiple reflection interference theory is used to analyze the mechanism of the absorber and the results are in good agreement with simulated and experimental results. Furthermore, the absorption properties are studied under various spacer thicknesses. This kind of metamaterial absorber is insensitive to polarization, has high absorption rates (over 90%) with wide incident angles range from 0° to 45° and the absorption rates are also above 90% when wrapping it to a curved surface.

  18. Oxygen absorbers in food preservation: a review.

    Science.gov (United States)

    Cichello, Simon Angelo

    2015-04-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world.

  19. Distributed Absorber for Noise and Vibration Control

    Directory of Open Access Journals (Sweden)

    Michel Azoulay

    2011-01-01

    Full Text Available An approach to a wide-band frequency passive vibration attenuation is introduced in this paper. This aims to suppress noise and vibration of extended multimode objects like plates, panels and shells. The absorber is arranged in the form of a single-layer assembly of small inertial bodies (balls being distributed and moulded within the light visco-elastic media (e.g. silicone resin. The absorber as a whole is embedded into object face covering the critical patches of the system surface. For the purpose of characterization, the authors introduced the complex frequency response function relating the volume velocity produced by the vibrating object surface (response stimulated by a point-wise force (stimulus applied to a particular point. The simulation and optimization of the main frequency characteristics has been performed using a full scale 3-dimensional Finite Element model. These revealed some new dynamic features of absorber's structures, which can contribute to vibration attenuation. A full-scale physical experimentation with synthesised absorber's structures confirmed the main results of simulation and has shown significant noise reduction over a staggering 0–20 kHz frequency band. This was achieved with a negligible weight and volume penalty due to the addition of the absorber. The results can find multiple applications in noise and vibration control of different structures. Some examples of such applications are presented.

  20. Thyroid dose distribution in dental radiography

    Energy Technology Data Exchange (ETDEWEB)

    Bristow, R.G.; Wood, R.E.; Clark, G.M. (Ontario Cancer Institute, Toronto (Canada))

    1989-10-01

    The anatomic position and proven radiosensitivity of the thyroid gland make it an organ of concern in dental radiography. A calibrated thermoluminescent dosimetry system was used to investigate the absorbed dose (microGy) to the thyroid gland resultant from a minimum irradiated volume, intraoral full-mouth radiography technique with the use of rectangular collimation with a lead-backed image receptor, and conventional panoramic radiography performed with front and rear lead aprons. Use of the minimum irradiated volume technique resulted in a significantly decreased absorbed dose over the entire thyroid region ranging from 100% to 350% (p less than 0.05). Because this intraoral technique results in radiographs with greater image quality and also exposes the thyroid gland to less radiation than the panoramic, this technique may be an alternative to the panoramic procedure.

  1. Evaluation of X ray radiation doses in pediatric examinations of cranial computerized tomography based on optimization studies; Avaliacao das doses de radiacao X em exames pediatricos de tomografia computadorizada de cranio com base em estudos de otimizacao

    Energy Technology Data Exchange (ETDEWEB)

    Daros, Kellen Adriana Curci

    2005-07-01

    This paper identifies the technical conditions for CT examination which offers lowest absorbed dose and to attend the manufacturer recommendations as far the spatial resolution is concerned. The paper evaluates the absorbed dose during cranial CT in up to 6 years children satisfying the technical condition recommended by the manufacturer and routine clinical conditions. The paper also established a quantitative relationship among the absorbed dose and its distribution in the cranial regions of pediatric patients up to 6 years old in a way to estimate the doses subject to optimized conditions

  2. Absorbing material based on starch having improved absorbent properties and process for the preparation thereof

    NARCIS (Netherlands)

    Feil, H.; Soest, van J.J.G.; Schijndel, van R.J.G.

    1999-01-01

    A biodegradable, highly water-absorbing polymer based on starch or derivatives thereof is described, wherein the starch has not been chemically modified or only to a degree of substitution below 0.2, and has a water-absorbing power of at least 10 times its own weight, half of the water absorption be

  3. Non-Absorbable Gas Behavior in the Absorber/Evaporator of a Absorption Chiller

    Science.gov (United States)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional numerical study on non-absorbable gas behavior in the absorber/evaporator of an absorption chiller has been performed. In the present study, the effect of the pitch-to-diameter ratio of a cylinder bundle in the absorber was highlighted. From the results, a sudden decrease of the overall heat transfer coefficient of the absorber was observed at a certain mean concentration of non-absorbable gas for each pitch-to-diameter ratio. Such a critical concentration was also found to decrease as the pitch-to- diameter ratio increased. The sudden decrease occurs due to the sudden disappearance of recirculating region, which is formed between the absorber and the evaporator, and where most of non-absorbable gas stays when it exists. As the pitch-to-diameter ratio increases, the recirculating region becomes weak because the velocity of the high velocity region supporting the recirculating flow decreases. Then, the critical mean concentration of non-absorbable gas is found to decrease as pitch-to-ratio increases.

  4. Interference theory of metamaterial perfect absorbers

    CERN Document Server

    Chen, Hou-Tong

    2011-01-01

    The impedance matching in metamaterial perfect absorbers has been believed to involve and rely on magnetic resonant response, with a direct evidence from the anti-parallel directions of surface currents in the metal structures. Here we present a different theoretical interpretation based on interferences, which shows that the two layers of metal structure in metamaterial absorbers are linked only by multiple reflections with negligible near-field interactions or magnetic resonances. This is further supported by the out-of-phase surface currents derived at the interfaces of resonator array and ground plane through multiple reflections and superpositions. The theory developed here explains all features observed in narrowband metamaterial absorbers and therefore provides a profound understanding of the underlying physics.

  5. Absorber Materials at Room and Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  6. Ferrite HOM Absorber for the RHIC ERL

    Energy Technology Data Exchange (ETDEWEB)

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  7. On the warm absorber in AGN outflow

    CERN Document Server

    Adhikari, T P; Sobolewska, M; Czerny, B

    2016-01-01

    Warm absorber (WA) is an ionised gas present in the line of sight to the AGN central engine. The effect of the absorber is imprinted in the absorption lines observed in X-ray spectra of AGN. In this work, we model the WA in Seyfert 1 galaxy Mrk 509 using its recently published shape of broad band spectral energy distribution (SED) as a continuum illuminating the absorber. Using the photoionization code {\\sc Titan}, recently we have shown that the absorption measure distribution (AMD) found for this object can be successfully modelled as a single slab of gas in total pressure (radiation+gas) equilibrium, contrary to the usual models of constant density multiple slabs. We discuss the transmitted spectrum that would be recorded by an observer after the radiation from the nucleus passes through the WA.

  8. Broadband plasmonic absorber for photonic integrated circuits

    CERN Document Server

    Xiong, Xiao; Ren, Xi-Feng; Guo, Guang-Can

    2013-01-01

    The loss of surface plasmon polaritons has long been considered as a fatal shortcoming in information transport. Here we propose a plasmonic absorber utilizing this "shortcoming" to absorb the stray light in photonic integrated circuits (PICs). Based on adiabatic mode evolution, its performance is insensitive to incident wavelength with bandwidth larger than 300nm, and robust against surrounding environment and temperature. Besides, the use of metal enables it to be very compact and beneficial to thermal dissipation. With this 40um-long absorber, the absorption efficiency can be over 99.8% at 1550nm, with both the reflectivity and transmittance of incident light reduced to less than 0.1%. Such device may find various applications in PICs, to eliminate the residual strong pump laser or stray light.

  9. Precise dispersion equations of absorbing filter glasses

    Science.gov (United States)

    Reichel, S.; Biertümpfel, Ralf

    2014-05-01

    The refractive indices versus wavelength of optical transparent glasses are measured at a few wavelengths only. In order to calculate the refractive index at any wavelength, a so-called Sellmeier series is used as an approximation of the wavelength dependent refractive index. Such a Sellmeier representation assumes an absorbing free (= loss less) material. In optical transparent glasses this assumption is valid since the absorption of such transparent glasses is very low. However, optical filter glasses have often a rather high absorbance in certain regions of the spectrum. The exact description of the wavelength dependent function of the refractive index is essential for an optimized design for sophisticated optical applications. Digital cameras use an IR cut filter to ensure good color rendition and image quality. In order to reduce ghost images by reflections and to be nearly angle independent absorbing filter glass is used, e.g. blue glass BG60 from SCHOTT. Nowadays digital cameras improve their performance and so the IR cut filter needs to be improved and thus the accurate knowledge of the refractive index (dispersion) of the used glasses must be known. But absorbing filter glass is not loss less as needed for a Sellmeier representation. In addition it is very difficult to measure it in the absorption region of the filter glass. We have focused a lot of effort on measuring the refractive index at specific wavelength for absorbing filter glass - even in the absorption region. It will be described how to do such a measurement. In addition we estimate the use of a Sellmeier representation for filter glasses. It turns out that in most cases a Sellmeier representation can be used even for absorbing filter glasses. Finally Sellmeier coefficients for the approximation of the refractive index will be given for different filter glasses.

  10. Shock-Absorbent Ball-Screw Mechanism

    Science.gov (United States)

    Hirr, Otto A., Jr.; Meneely, R. W.

    1986-01-01

    Actuator containing two ball screws in series employs Belleville springs to reduce impact loads, thereby increasing life expectancy. New application of springs increases reliability of equipment in which ball screws commonly used. Set of three springs within lower screw of ball-screw mechanism absorbs impacts that result when parts reach their upper and lower limits of movement. Mechanism designed with Belleville springs as shock-absorbing elements because springs have good energy-to-volume ratio and easily stacked to attain any stiffness and travel.

  11. Optically Modulated Multiband Terahertz Perfect Absorber

    DEFF Research Database (Denmark)

    Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue

    2014-01-01

    response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented....... Utilizing photo-excited free carriers in silicon padsplaced in the capacitive gaps of split ring resonators, a dynamically modu-lated perfect absorber is designed and fabricated to operate in reflection.Large modulation depth (38% and 91%) in two absorption bands (with 97%and 92% peak absorption...

  12. Quantum walk with one variable absorbing boundary

    Science.gov (United States)

    Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli

    2017-01-01

    Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks.

  13. Spin Particle in an Absorbing Environment

    Science.gov (United States)

    Amooshahi, M.

    2015-10-01

    The quantum dynamics of a localized spin Particle interacting with an absorbing environment is investigated. The quantum Langevin-Schrödinger equation for spin is obtained. The susceptibility function of the environment is calculated in terms of the coupling function of the spin and the environment. it is shown that the susceptibility function satisfies the Kramers-Kronig relations. Spontaneous emission and the shift frequency of the spin is obtained in terms of the imaginary part of the susceptibility function in frequency domain. Some transition probabilities between the spin states are calculated when the absorbing environment is in the thermal state.

  14. Timing the warm absorber in NGC 4051

    Science.gov (United States)

    Silva, C. V.; Uttley, P.; Costantini, E.

    2016-12-01

    We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results of the extensive 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051 whose spectrum has revealed a complex multicomponent wind. Making use of both RGS and EPIC-pn data, we performed a detailed analysis through a time-dependent photoionization code in combination with spectral and Fourier spectral-timing techniques. The source light curves and the warm absorber parameters obtained from the data were used to simulate the response of the gas to variations in the ionizing flux of the central source. The resulting time variable spectra were employed to predict the effects of the warm absorber on the time lags and coherence of the energy dependent light curves. We have found that, in the absence of any other lag mechanisms, a warm absorber with the characteristics of the one observed in NGC 4051, is able to produce soft lags, up to 100 s, on timescales of hours. The time delay is associated with the response of the gas to changes in the ionizing source, either by photoionization or radiative recombination, which is dependent on its density. The range of radial distances that, under our assumptions, yield longer time delays are distances r 0.3-1.0 × 1016 cm, and hence gas densities n 0.4-3.0 × 107 cm-3. Since these ranges are comparable to the existing estimates of the location of the warm absorber in NGC 4051, we suggest that it is likely that the observed X-ray time lags may carry a signature of the warm absorber response time to changes in the ionizing continuum. Our results show that the warm absorber in NGC 4051 does not introduce lags on the short timescales associated with reverberation, but will likely modify the hard continuum lags seen on longer timescales, which in this source have been measured to be on the order of 50 s. Hence, these

  15. Durability of Polymeric Glazing and Absorber Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  16. 21 CFR 880.6025 - Absorbent tipped applicator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbent tipped applicator. 880.6025 Section 880... Devices § 880.6025 Absorbent tipped applicator. (a) Identification. An absorbent tipped applicator is a device intended for medical purposes that consists of an absorbent swab on a wooden, paper, or...

  17. 21 CFR 880.5300 - Medical absorbent fiber.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical absorbent fiber. 880.5300 Section 880.5300... Devices § 880.5300 Medical absorbent fiber. (a) Identification. A medical absorbent fiber is a device...'s body surface. Absorbent fibers intended solely for cosmetic purposes are not included in...

  18. Can polar bear hairs absorb environmental energy?

    OpenAIRE

    He Ji-Huan; Wang Qing-Li; Sun Jie

    2011-01-01

    A polar bear (Ursus maritimus) has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  19. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  20. Timing the warm absorber in NGC 4051

    CERN Document Server

    Silva, Catia; Costantini, Elisa

    2016-01-01

    We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results on the extensive ~ 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051, whose spectrum has revealed a complex multicomponent wind. Making use of both RGS and EPIC-pn data, we performed a detailed analysis through a time-dependent photoionization code in combination with spectral and Fourier spectral-timing techniques. The source light curves and the warm absorber parameters obtained from the data were used to simulate the response of the gas due to variations in the ionizing flux of the central source. The resulting time variable spectra were employed to predict the effects of the warm absorber on the time lags and coherence of the energy dependent light curves. We have found that, in the absence of any other lag mechanisms, a warm absorber with the characteristics of the one observed ...

  1. Tunable metamaterial dual-band terahertz absorber

    Science.gov (United States)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.

    2015-11-01

    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  2. Review of Plasmonic Nanocomposite Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Mehdi Keshavarz Hedayati

    2014-02-01

    Full Text Available Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon. These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented.

  3. Microstructured extremely thin absorber solar cells

    DEFF Research Database (Denmark)

    Biancardo, Matteo; Krebs, Frederik C

    2007-01-01

    In this paper we present the realization of extremely thin absorber (ETA) solar cells employing conductive glass substrates functionalized with TiO2 microstructures produced by embossing. Nanocrystalline or compact TiO2 films on Indium doped tin oxide (ITO) glass substrates were embossed...

  4. A variable passive low-frequency absorber

    DEFF Research Database (Denmark)

    Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders

    2005-01-01

    typically been too expensive or requires too much space to be practical for multi-purpose halls. Measurements were made on a variable low-frequency absorber to develop a practical solution to the dilemma. The paper will present the results of the measurements as well as a possible design....

  5. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    2010-01-01

    We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

  6. Moving core beam energy absorber and converter

    Science.gov (United States)

    Degtiarenko, Pavel V.

    2012-12-18

    A method and apparatus for the prevention of overheating of laser or particle beam impact zones through the use of a moving-in-the-coolant-flow arrangement for the energy absorbing core of the device. Moving of the core spreads the energy deposition in it in 1, 2, or 3 dimensions, thus increasing the effective cooling area of the device.

  7. Measurement of the primary and scatter dose in high energy photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Van der Linden, P.M. [Catharina Ziekenhuis, Eindhoven (Netherlands). Radiotherapy Dept.; Tiourina, T.B.; Dries, W.

    1995-12-01

    A method is presented to measure the primary and scatter components separately in a water tank using a small cylindrical absorber. Results from this experiment are compared with Monte Carlo calculations. The measurement setup consists of a small cylindrical absorber placed on a central axis of the beam a few centimetres above the radiation detector. Both absorber and detector move along the central axis while absorbed dose is registered. As the primary radiation is fully blocked, only scatter component is measured when a cylindrical absorber is used. Measurements in open fields result in the total absorbed dose being the sum of primary and scatter components. The primary dose component can be derived by substraction. Absorbers with different diameters are used. With decreasing dimensions the relative contribution of the dose due to scatter radiation increases. A steep increase is observed when the range of laterally scattered electrons becomes comparable with the radius of the absorber. Two different Monte Carlo simulations have been performed: with and without secondary electron transport. The data obtained for the former case perfectly agrees with the experiment. The situation where the secondary electron is assumed zero (i.e. local energy deposition) simulates the Cunningham model. Our results show that the Cunningham model predicts lower scatter component under the block edge which can be important for these applications.

  8. Neutron dose estimation in a zero power nuclear reactor

    Science.gov (United States)

    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. Dose and volume specification for reporting interstitial therapy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-30

    The ICRU has previously published reports dealing with Dose Specification for Reporting External Beam Therapy with Photons and Electrons (ICRU Report 29, ICRU, 1978), Dose Specification for Reporting External Beam Therapy (ICRU Report 50, ICRU, 1993) and Dose and Volume Specification for Reporting Intracavitary Therapy in Gynecology (ICRU Report 38, ICRU, 1985). The present report addresses the problem of absorbed dose specification for report interstitial therapy. Although specific to interstitial therapy, many of the concepts developed in this report are also applicable to certain other kinds of brachytherapy applications. In particular, special cases of intraluminal brachytherapy and plesio-brachytherapy via surface molds employing x or gamma emitters are addressed in this report.

  10. Prompt-gamma detection towards absorbed energy monitoring during hadrontherapy

    Energy Technology Data Exchange (ETDEWEB)

    Krimmer, J.; Balleyguier, L.; Dauvergne, D.; Mathez, H.; Pinto, M.; Testa, E.; Zoccarato, Y. [Institut de Physique Nucleaire de Lyon, Universite de Lyon, Universite de Lyon 1, IN2P3/CNRS, UMR 5822, F-69622 Villeurbanne cedex (France); Krimmer, J.; Freud, N.; L' etang, J.M. [Universite de Lyon, CREATIS, CNRS UMR 5220, Inserm U1044, INSA - Lyon, Universite Lyon 1, Centre Leon Berard (France); Herault, J.; Amblard, R.; Angellier, G. [Centre Antoine Lacassagne, Cyclotron Biomedical, 227 Avenue de la Lanterne, 06200 Nice (France)

    2015-07-01

    Hadrontherapy is an emerging technique which exploits the fact that a large quantity of the energy of the incident particles is deposited at the end of their flight path. This allows a conformation of the applied dose to the tumor volume and a simultaneous sparing of surrounding healthy tissue. A real-time control of the ion range during the treatment is possible via the detection of prompt secondary radiation (gamma rays or charged particles). Besides a monitoring of the ion range, the knowledge of the total energy absorbed inside the patient is also of importance for an improvement of the treatment quality. It has been shown that the ambient dose in a treatment room is correlated to the monitoring units, i.e. the number of protons of the beam delivery system. The present study consists in applying time-of-flight (TOF) information to identify prompt gamma-rays generated by interactions inside the patient which provides a direct information on the energy imparted. Results from test measurements will be given, which show that events generated in the nozzle and the target phantom can be discriminated. Furthermore, a standalone detection system is being developed which will be read out by a standard PC. The status of the developments for the corresponding electronics will be presented. (authors)

  11. Method for calculating dose when lung tissue lies in the treatment field

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, S.C.; Keller, B.E.; Rubin, P.

    1976-07-01

    The absorbed dose in lung and beyond lung as a result of increased lung transmission of x and ..gamma.. irradiation is described. The correction factor used to calculate the absorbed dose is a function of beam energy, field area, lung density, and lung and soft tissue depth. Agreement between measurements and calculations in the Alderson phantom is within 3%. An example of how this technique can be used is described. (AIP)

  12. Analytical evaluation of dose measurement of critical accident at SILENE (Contract research)

    CERN Document Server

    Nakamura, T; Tonoike, K

    2003-01-01

    Institute for Radioprotection and Nuclear Safety (IRSN) and the OECD Nuclear Energy Agency (NEA) jointly organized SILENE Accident Dosimetry Intercomparison Exercise to intercompare the dose measurement systems of participating countries. Each participating country carried out dose measurements in the same irradiation field, and the measurement results were mutually compared. The participated in the exercise to measure the doses of gamma rays and neutron from SILENE by using thermoluminescence dosimeters (TLD's) and an alanine dosimeter. In this examination, the derived evaluation formulae for obtaining a tissue-absorbed dose from measured value (ambient dose equivalent) of TLD for neutron. We reported the tissue-absorbed dose computed using this evaluation formula to OECD/NEA. TLD's for neutron were irradiated in the TRACY facility to verify the evaluation formulae. The results of TLD's were compared with the calculations of MCNP and measurements with alanine dose meter. We found that the ratio of the dose b...

  13. Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yang; Xu, Yonggang, E-mail: xuyonggang221@163.com; Cai, Jun; Yuan, Liming; Zhang, Deyuan

    2015-09-01

    Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1–4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches −7.8 dB), and as the RL was less than −10 dB the absorption band was widest (2.1–3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band. - Graphical abstract: Morphology of composites filled with flaky CIPs and the bio-absorbent. The enhancement of bio-absorbent on the electromagnetic absorption property of composites filled with flaky carbonyl iron particles (CIPs) is attributed to the interaction of the two absorbents. The volume content of the FCMPs with the larger shape CIPs play an important role in this effects, the composites filled with irons and bio-absorbents can achieve wider-band and thinner-thickness absorbing materials. - Highlights: • Absorbers filled with bio-absorbents and CIPs was fabricated. • Bio-absorbents enhanced the permittivity and permeability of the composites. • The absorbent interactions play a key role in the enhancement mechanism. • Bio-absorbents enhanced the composite RL in 1–4 GHz.

  14. Acoustic dose and acoustic dose-rate.

    Science.gov (United States)

    Duck, Francis

    2009-10-01

    Acoustic dose is defined as the energy deposited by absorption of an acoustic wave per unit mass of the medium supporting the wave. Expressions for acoustic dose and acoustic dose-rate are given for plane-wave conditions, including temporal and frequency dependencies of energy deposition. The relationship between the acoustic dose-rate and the resulting temperature increase is explored, as is the relationship between acoustic dose-rate and radiation force. Energy transfer from the wave to the medium by means of acoustic cavitation is considered, and an approach is proposed in principle that could allow cavitation to be included within the proposed definitions of acoustic dose and acoustic dose-rate.

  15. A quality index for equivalent uniform dose

    Science.gov (United States)

    Henríquez, Francisco Cutanda; Castrillón, Silvia Vargas

    2011-01-01

    Equivalent uniform dose (EUD) is the absorbed dose that, when homogeneously given to a tumor, yields the same mean surviving clonogen number as the given non-homogeneous irradiation. EUD is used as an evaluation tool under the assumption that two plans with the same value of EUD are equivalent, and their biological effect on the tumor (clonogen survival) would be the same as the one of a homogeneous irradiation of absorbed dose EUD. In this work, this assumption has been studied, and a figure of merit of its applicability has been obtained. Distributions of surviving clonogen number for homogeneous and non-homogeneous irradiations are found to be different even if their mean values are the same, the figure of merit being greater when there is a wider difference, and the equivalence assumption being less valid. Therefore, EUD can be closer to a uniform dose for some cases than for other ones (high α values, extreme heterogeneity), and the accuracy of the radiobiological indices obtained for evaluation, could be affected. Results show that the equivalence is very sensitive to the choice of radiobiological parameters, and this conclusion has been derived from mathematical properties of EUD. PMID:21897557

  16. A sound absorbing metasurface with coupled resonators

    Science.gov (United States)

    Li, Junfei; Wang, Wenqi; Xie, Yangbo; Popa, Bogdan-Ioan; Cummer, Steven A.

    2016-08-01

    An impedance matched surface is able, in principle, to totally absorb the incident sound and yield no reflection, and this is desired in many acoustic applications. Here we demonstrate a design of impedance matched sound absorbing surface with a simple construction. By coupling different resonators and generating a hybrid resonance mode, we designed and fabricated a metasurface that is impedance-matched to airborne sound at tunable frequencies with subwavelength scale unit cells. With careful design of the coupled resonators, over 99% energy absorption at central frequency of 511 Hz with a 50% absorption bandwidth of 140 Hz is achieved experimentally. The proposed design can be easily fabricated, and is mechanically stable. The proposed metasurface can be used in many sound absorption applications such as loudspeaker design and architectural acoustics.

  17. Absorbing angles, Steiner minimal trees, and antipodality

    CERN Document Server

    Martini, Horst; de Wet, P Oloff; 10.1007/s10957-009-9552-1

    2011-01-01

    We give a new proof that a star $\\{op_i:i=1,...,k\\}$ in a normed plane is a Steiner minimal tree of its vertices $\\{o,p_1,...,p_k\\}$ if and only if all angles formed by the edges at o are absorbing [Swanepoel, Networks \\textbf{36} (2000), 104--113]. The proof is more conceptual and simpler than the original one. We also find a new sufficient condition for higher-dimensional normed spaces to share this characterization. In particular, a star $\\{op_i: i=1,...,k\\}$ in any CL-space is a Steiner minimal tree of its vertices $\\{o,p_1,...,p_k\\}$ if and only if all angles are absorbing, which in turn holds if and only if all distances between the normalizations $\\frac{1}{\\|p_i\\|}p_i$ equal 2. CL-spaces include the mixed $\\ell_1$ and $\\ell_\\infty$ sum of finitely many copies of $R^1$.

  18. Preparation of perlite-based carbon dioxide absorbent.

    Science.gov (United States)

    He, H; Wu, L; Zhu, J; Yu, B

    1994-02-01

    A new highly efficient carbon dioxide absorbent consisting of sodium hydroxide, expanded perlite and acid-base indicator was prepared. The absorption efficiency, absorption capacity, flow resistance and color indication for the absorbent were tested and compared with some commercial products. The absorbent can reduce the carbon dioxide content in gases to 3.3 ppb (v/v) and absorbs not less than 35% of its weight of carbon dioxide. Besides its large capacity and sharp color indication, the absorbent has an outstanding advantage of small flow resistance in comparison with other commercial carbon dioxide absorbents. Applications in gas analysis and purification were also investigated.

  19. VUV Absorbing Vapours in n-Perfluorocarbons

    CERN Document Server

    Albrecht, E; Bellunato, T F; Bressan, A; Dalla Torre, S; D'Ambrosio, C; Davenport, M; Dragicevic, M; Duarte-Pinto, S; Fauland, P; Ilie, S; Lenzen, Georg; Pagano, P; Piedigrossi, D; Tessarotto, F; Ullaland, O

    2003-01-01

    The optical transparency of perfluorocarbons used as Cherenkov media is of prime importance to many Ring Imaging Cherenkov detectors. We will in this paper show that the main photon absorbers in these fluids are hydrocarbons with double or triple bonds. We will moreover discuss a process which can eliminate these pollutants and restore the intrinsic excellent optical transparency of these fluids in the VUV range.

  20. 2D Saturable Absorbers for Fibre Lasers

    Directory of Open Access Journals (Sweden)

    Robert I. Woodward

    2015-11-01

    Full Text Available Two-dimensional (2D nanomaterials are an emergent and promising platform for future photonic and optoelectronic applications. Here, we review recent progress demonstrating the application of 2D nanomaterials as versatile, wideband saturable absorbers for Q-switching and mode-locking fibre lasers. We focus specifically on the family of few-layer transition metal dichalcogenides, including MoS2, MoSe2 and WS2.

  1. Oxygen absorbers in food preservation: a review

    OpenAIRE

    Cichello, Simon Angelo

    2014-01-01

    The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen imperme...

  2. Dose reconstruction of X-ray irradiation of the larynx

    Energy Technology Data Exchange (ETDEWEB)

    Takacsi-Nagy, L.; Weisz, C.; Zarand, P.; Nemeth, G.

    1987-05-01

    The authors have determined the dose distribution in the neck for parallel opposed and three field orthovoltage X-ray irradiation techniques of cc. laringis. LiF:Mg, Ti rods and pellets combined with film densitometry were used. Absorbed dose measured in the region of vocal chords is about 20% lower than that assessed by assuming full backscatter (perpendicular incidence) and by using standard isodose tables.

  3. Collision-kerma conversion between dose-to-tissue and dose-to-water by photon energy-fluence corrections in low-energy brachytherapy

    Science.gov (United States)

    Giménez-Alventosa, Vicent; Antunes, Paula C. G.; Vijande, Javier; Ballester, Facundo; Pérez-Calatayud, José; Andreo, Pedro

    2017-01-01

    The AAPM TG-43 brachytherapy dosimetry formalism, introduced in 1995, has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations, except in the vicinity of the source capsule. Subsequent dosimetry developments, based on Monte Carlo calculations or analytical solutions of transport equations, do not rely on the CPE assumption and determine directly the dose to different tissues. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seeds is proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences. State-of-the art Monte Carlo calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone), which in all cases include a realistic modelling of low-energy brachytherapy sources in order to benchmark the formalism proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases (e.g. bone tissue).

  4. An example of problems in dose reconstruction from doses formed by electromagnetic irradiation by different energy sources.

    Science.gov (United States)

    Kirillov, Vladimir; Kuchuro, Joseph; Tolstik, Sergey; Leonova, Tatyana

    2010-02-01

    Dose reconstruction for citizens of Belarus affected by the Chernobyl accident showed an unexpectedly wide range of doses. Using the EPR tooth enamel dosimetry method, it has been demonstrated that when the tooth enamel dose was formed due to x-rays with effective energy of 34 keV and the additional irradiation of enamel samples was performed by gamma radiation with mean energy of 1,250 keV, it led to a considerable increase in the reconstructed absorbed dose as compared with the applied. In the case when the dose was formed due to gamma radiation and the additional irradiation was performed by x-rays, it led to a considerable decrease in the reconstructed dose as compared with the applied. When the dose formation and the additional irradiation were carried out from external sources of electromagnetic radiation of equal energy, the reconstructed dose value was close to that of the applied. The obtained data show that for adequate reconstruction of individual absorbed doses by the EPR tooth enamel spectra, it is necessary to take into account the contribution from diagnostic x-ray examination of the teeth, jaw, and skull of some individuals who were exposed to a combined effect of the external gamma radiation and x-rays.

  5. Prediction of in-phantom dose distribution using in-air neutron beam characteristics for BNCS

    Energy Technology Data Exchange (ETDEWEB)

    Verbeke, Jerome M.

    1999-12-14

    A monoenergetic neutron beam simulation study is carried out to determine the optimal neutron energy range for treatment of rheumatoid arthritis using radiation synovectomy. The goal of the treatment is the ablation of diseased synovial membranes in joints, such as knees and fingers. This study focuses on human knee joints. Two figures-of-merit are used to measure the neutron beam quality, the ratio of the synovium absorbed dose to the skin absorbed dose, and the ratio of the synovium absorbed dose to the bone absorbed dose. It was found that (a) thermal neutron beams are optimal for treatment, (b) similar absorbed dose rates and therapeutic ratios are obtained with monodirectional and isotropic neutron beams. Computation of the dose distribution in a human knee requires the simulation of particle transport from the neutron source to the knee phantom through the moderator. A method was developed to predict the dose distribution in a knee phantom from any neutron and photon beam spectra incident on the knee. This method was revealed to be reasonably accurate and enabled one to reduce by a factor of 10 the particle transport simulation time by modeling the moderator only.

  6. Using the Monte Carlo method for assessing the tissue and organ doses of patients in dental radiography

    Science.gov (United States)

    Makarevich, K. O.; Minenko, V. F.; Verenich, K. A.; Kuten, S. A.

    2016-05-01

    This work is dedicated to modeling dental radiographic examinations to assess the absorbed doses of patients and effective doses. For simulating X-ray spectra, the TASMIP empirical model is used. Doses are assessed on the basis of the Monte Carlo method by using MCNP code for voxel phantoms of ICRP. The results of the assessment of doses to individual organs and effective doses for different types of dental examinations and features of X-ray tube are presented.

  7. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    Science.gov (United States)

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  8. Radiation dose reduction efficiency of buildings after the accident at the Fukushima Daiichi Nuclear Power Station.

    Directory of Open Access Journals (Sweden)

    Satoru Monzen

    Full Text Available Numerous radionuclides were released from the Fukushima Daiichi Nuclear Power Station (F1-NPS in Japan following the magnitude 9.0 earthquake and tsunami on March 11, 2011. Local residents have been eager to calculate their individual radiation exposure. Thus, absorbed dose rates in the indoor and outdoor air at evacuation sites in the Fukushima Prefecture were measured using a gamma-ray measuring devices, and individual radiation exposure was calculated by assessing the radiation dose reduction efficiency (defined as the ratio of absorbed dose rate in the indoor air to the absorbed dose rate in the outdoor air of wood, aluminum, and reinforced concrete buildings. Between March 2011 and July 2011, dose reduction efficiencies of wood, aluminum, and reinforced concrete buildings were 0.55 ± 0.04, 0.15 ± 0.02, and 0.19 ± 0.04, respectively. The reduction efficiency of wood structures was 1.4 times higher than that reported by the International Atomic Energy Agency. The efficiency of reinforced concrete was similar to previously reported values, whereas that of aluminum structures has not been previously reported. Dose reduction efficiency increased in proportion to the distance from F1-NPS at 8 of the 18 evacuation sites. Time variations did not reflect dose reduction efficiencies at evacuation sites although absorbed dose rates in the outdoor air decreased. These data suggest that dose reduction efficiency depends on structure types, levels of contamination, and evacuee behaviors at evacuation sites.

  9. Benchmark Dose Modeling

    Science.gov (United States)

    Finite doses are employed in experimental toxicology studies. Under the traditional methodology, the point of departure (POD) value for low dose extrapolation is identified as one of these doses. Dose spacing necessarily precludes a more accurate description of the POD value. ...

  10. Slow and Fast Light in an Electro-Absorber

    DEFF Research Database (Denmark)

    Öhman, Filip; Bermejo Ramirez, Andres; Sales, Salvador

    2006-01-01

    We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated.......We demonstrate controllable and large time delay in cascaded semiconductor saturable absorbers and amplifiers. The possibility of further increasing the tuneable phase shift by utilizing field screening effects in the quantum well absorber is demonstrated....

  11. Method for absorbing an ion from a fluid

    Science.gov (United States)

    Gao, Huizhen; Wang, Yifeng; Bryan, Charles R.

    2007-07-03

    A method for absorbing an ion from a fluid by using dispersing an organic acid into an anion surfactant solution, mixing in a divalent-metal containing compound and a trivalent-metal containing compound and calcining the resulting solid layered double hydroxide product to form an absorbent material and then contacting the absorbent material with an aqueous solution of cations or anions to be absorbed.

  12. Effect of inclusions' distribution on microwave absorbing properties of composites

    Science.gov (United States)

    Qin, Siliang; Wang, Qingguo; Qu, Zhaoming

    2013-03-01

    Effect of inclusions' spatial distributions on the permeability and permittivity of composites is studied using the generalized Maxwell-Garnett equations. The result indicates that inclusions' orientation distribution can increase the longitudinal electromagnetic parameters. For inclusions' random and orientation distribution, single and three-layer absorbers are designed and optimized using genetic algorithm. The result shows that under a given absorbing requirement, absorber with inclusions' orientation distribution is lighter and thinner than absorber with inclusions' random distribution.

  13. 21 CFR 868.5300 - Carbon dioxide absorbent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorbent. 868.5300 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5300 Carbon dioxide absorbent. (a) Identification. A carbon dioxide absorbent is a device intended for medical purposes that consists of...

  14. 21 CFR 868.5310 - Carbon dioxide absorber.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carbon dioxide absorber. 868.5310 Section 868.5310...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5310 Carbon dioxide absorber. (a) Identification. A carbon dioxide absorber is a device that is intended for medical purposes and that is used in...

  15. Adaptive Seat Energy Absorbers for Enhanced Crash Safety: Technology Demonstration

    Science.gov (United States)

    2016-08-01

    ARL-TR-7743 ● AUG 2016 US Army Research Laboratory Adaptive Seat Energy Absorbers for Enhanced Crash Safety: Technology...AUG 2016 US Army Research Laboratory Adaptive Seat Energy Absorbers for Enhanced Crash Safety: Technology Demonstration by Muthuvel...COVERED (From - To) 10 January 2012–29 February 2016 4. TITLE AND SUBTITLE Adaptive Seat Energy Absorbers for Enhanced Crash Safety: Technology

  16. About sound mufflers sound-absorbing panels aircraft engine

    Science.gov (United States)

    Dudarev, A. S.; Bulbovich, R. V.; Svirshchev, V. I.

    2016-10-01

    The article provides a formula for calculating the frequency of sound absorbed panel with a perforated wall. And although the sound absorbing structure is a set of resonators Helmholtz, not individual resonators should be considered in acoustic calculations, and all the perforated wall panel. The analysis, showing how the parameters affect the size and sound-absorbing structures in the absorption rate.

  17. A MICROGAP SURGE ABSORBER FABRICATED USING CONVENTIONAL SEMICONDUCTOR TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    李宏; 阮航宇

    2001-01-01

    A new type microgap surge absorber fabricated by only semiconductor technique has in it a special structure silicon chip which forms microgaps for gas discharge with electrodes, and has advantages such as small size, low cost, suitability for mass production besides the desirable characteristics that common microgap surge absorbers have. Applications of this absorber in communication facilities are discussed.

  18. 21 CFR 886.3300 - Absorbable implant (scleral buckling method).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Absorbable implant (scleral buckling method). 886... SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Prosthetic Devices § 886.3300 Absorbable implant (scleral buckling method). (a) Identification. An absorbable implant (scleral buckling method) is a...

  19. Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach.

    Science.gov (United States)

    Andryieuski, Andrei; Lavrinenko, Andrei V

    2013-04-08

    In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers.

  20. Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Lavrinenko, Andrei

    2013-01-01

    In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity...... we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers....

  1. [Absorbable coronary stents. New promising technology].

    Science.gov (United States)

    Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

    2007-06-01

    Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal. The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated. Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion

  2. [Performance of desulfurizing absorbent of roasted navajoite].

    Science.gov (United States)

    Chen, Fang; Yang, Chun-ping; Gan, Hai-ming; Wu, Ting; Chen, Hai-lin; Chen, Hong; Xu, Ke-hui; Xie, Geng-xin

    2010-04-01

    An innovative flue gas desulfurization (FGD) coupling process was proposed in this study to overcome the problems in wet-type limestone/lime processes which include fouling, clogging, and difficulty of selling the by-products and the problems in traditional process for vanadium extraction from navajoite ore such as excessive consumption of sulfuric acid and emissions of pollutants. The performance of a jet bubbling reactor (JBR) at pilot-scale was evaluated using navajoite ore produced in the process of extracting vanadium pentoxide as desulfurization absorbent. Results showed that navajoite ore slurry achieved better desulfurization performance than limestone slurry. When the inlet flue gas pressure drop was 3.0 kPa, the gas flow was about 2350 m3 x h(-1) and the pH of the navajoite ore slurry was higher than 4.5, the desulfurization efficiency was stable about 90%. The SO2 removal efficiency appeared to increase along with the increasing of absorbent cycle-index. The efficiency of the second circulation was improved 3.5% compared to the first circulation. After an operating duration of 40 minutes, the leaching rate of vanadium pentoxide was about 20%, and reached 60% when the by-products were leached with 5% dilute sulfuric acid for 10 hours. The by-product from this process not only could be used to produce vanadium pentoxide which is a valuable industrial product, but also could significantly overcome the pollution problem existing in the traditional refining process of vanadium pentoxide when navajoite ore is used as the feed material. This FGD process using roasted navajoite slurry as absorbent is environmental sound and cost-effective, and shows the potential for application in the field of flue gas desulfurization as well as hydrometallurgy.

  3. Radiation Dose Risk and Diagnostic Benefit in Imaging Investigations

    CERN Document Server

    Dobrescu, Lidia

    2015-01-01

    The paper presents many facets of medical imaging investigations radiological risks. The total volume of prescribed medical investigations proves a serious lack in monitoring and tracking of the cumulative radiation doses in many health services. Modern radiological investigations equipment is continuously reducing the total dose of radiation due to improved technologies, so a decrease in per caput dose can be noticed, but the increasing number of investigations has determined a net increase of the annual collective dose. High doses of radiation are cumulated from Computed Tomography investigations. An integrated system for radiation safety of the patients investigated by radiological imaging methods, based on smart cards and Public Key Infrastructure allow radiation absorbed dose data storage.

  4. Acoustical model of a Shoddy fibre absorber

    Science.gov (United States)

    Manning, John Peter

    Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz

  5. A novel broadband waterborne acoustic absorber

    Science.gov (United States)

    Wang, Changxian; Wen, Weibin; Huang, Yixing; Chen, Mingji; Lei, Hongshuai; Fang, Daining

    2016-07-01

    In this paper, we extended the ray tracing theory in polar coordinate system, and originally proposed the Snell-Descartes law in polar coordinates. Based on these theories, a novel broadband waterborne acoustic absorber device was proposed. This device is designed with gradient-distributing materials along radius, which makes the incidence acoustic wave ray warps. The echo reduction effects of this device were investigated by finite element analysis, and the numerical results show that the reflectivity of acoustic wave for the new device is lower than that of homogenous and Alberich layers in almost all frequency 0-30 kHz at the same loss factor.

  6. DHCAL with Minimal Absorber: Measurements with Positrons

    CERN Document Server

    Freund, B; Repond, J.; Schlereth, J.; Xia, L.; Dotti, A.; Grefe, C.; Ivantchenko, V.; Antequera, J.Berenguer; Calvo Alamillo, E.; Fouz, M.C.; Marin, J.; Puerta-Pelayo, J.; Verdugo, A.; Brianne, E.; Ebrahimi, A.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Irles, A.; Krivan, F.; Krüger, K.; Kvasnicka, J.; Lu, S.; Lutz, B.; Morgunov, V.; Provenza, A.; Reinecke, M.; Sefkow, F.; Schuwalow, S.; Tran, H.L.; Garutti, E.; Laurien, S.; Matysek, M.; Ramilli, M.; Schroeder, S.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kovalcuk, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; van Doren, B.; Wilson, G.W.; Kawagoe, K.; Hirai, H.; Sudo, Y.; Suehara, T.; Sumida, H.; Takada, S.; Tomita, T.; Yoshioka, T.; Bilokin, S.; Bonis, J.; Cornebise, P.; Pöschl, R.; Richard, F.; Thiebault, A.; Zerwas, D.; Hostachy, J.Y.; Morin, L.; Besson, D.; Chadeeva, M.; Danilov, M.; Markin, O.; Popova, E.; Gabriel, M.; Goecke, P.; Kiesling, C.; Kolk, N.van der; Simon, F.; Szalay, M.; Corriveau, F.; Blazey, G.C.; Dyshkant, A.; Francis, K.; Zutshi, V.; Kotera, K.; Ono, H.; Takeshita, T.; Ieki, S.; Kamiya, Y.; Ootani, W.; Shibata, N.; Jeans, D.; Komamiya, S.; Nakanishi, H.

    2016-01-01

    In special tests, the active layers of the CALICE Digital Hadron Calorimeter prototype, the DHCAL, were exposed to low energy particle beams, without being interleaved by absorber plates. The thickness of each layer corresponded approximately to 0.29 radiation lengths or 0.034 nuclear interaction lengths, defined mostly by the copper and steel skins of the detector cassettes. This paper reports on measurements performed with this device in the Fermilab test beam with positrons in the energy range of 1 to 10 GeV. The measurements are compared to simulations based on GEANT4 and a standalone program to emulate the detailed response of the active elements.

  7. Absorbency of Superabsorbent Polymers in Cementitious Environments

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro; Jensen, Ole Mejlhede

    2012-01-01

    Optimal use of superabsorbent polymers (SAP) in cement-based materials relies on knowledge on how SAP absorbency is influenced by different physical and chemical parameters. These parameters include salt concentration in the pore fluid, temperature of the system and SAP particle size. The present...... composition of the exposure liquid is investigated with atomic absorption spectroscopy. The paper provides the reader with knowledge about the absorption capacity of SAP in a cementitious environment, and how the absorption process may influence the cement pore fluid....

  8. Heat Transfer Performance of Absorber of Absorption Refrigerating Machine

    Science.gov (United States)

    Kunugi, Yoshifumi; Ouchi, Tomihisa; Usui, Sanpei; Fukuda, Tamio

    Experimental studies on heat transfer performance of absorber for lithium bromide-water absorption refrigerating machine are presented in this paper. Experimental apparatus for 35 kW evaporator and absorber, and outer grooved tubes are used. As a result, over-al1 coefficient of heat transmission of absorber has a maximum value, in the case of heat transfer area ratio of absorber to evaporator, is about 0.8. Heat transfer rate of absorber is increased by 60% by using the outer grooved tube compared with the plane surfaced tube.

  9. Tracking Performances of Several Front-Absorber Designs

    CERN Document Server

    Lautridou, P; CERN. Geneva; Métivier, V; Rahmani, A; Ramillien, V; Reposeur, T; Morsch, Andreas; Cussonneau, J P

    1998-01-01

    The tracking performances of the ALICE forward muon spectrometer are investigated for several front-absorbers designs. The obtained mass resolution is compared to the one of the absorber proposed in the LOI. Out of punchthrough considerations, two absorbers compositions, including a Carbon+Concrete sandwich design, allow to reach the requested mass resolution for the Y's. Almost identical behaviours are observed versus rapidity and transverse momentum of resonances for both new candidates. These proposed designs improve the mass resolution performances and could stand as suitable absorber options for the forward muon spectrometer of ALICE. The Carbon+Concrete absorber has been retained for the Technical Proposal [1].

  10. Background study of absorbed dose in biological experiments at the Modane Underground Laboratory

    Science.gov (United States)

    Lampe, Nathanael; Marin, Pierre; Castor, Jean; Warot, Guillaume; Incerti, S.; Maigne, Lydia; Sarramia, David; Breton, Vincent

    2016-09-01

    Aiming to explore how biological systems respond to ultra-low background environ-ments, we report here our background studies for biological experiments in the Modane Under-ground Laboratory. We find that the minimum radioactive background for biology experiments is limited by the potassium content of the biological sample itself, coming from its nutritive me-dium, which we find in our experimental set-up to be 26 nGy hr-1. Compared to our reference radiation environment in Clermont-Ferrand, biological experiments can be conducted in the Modane laboratory with a radiation background 8.2 times lower than the reference above-ground level. As the radiation background may be further reduced by using different nutritive media, we also provide measurements of the potassium concentration by gamma spectroscopy of yeast extract (63.3±1.2 mg g-1) and tryptone (2.5±0.2 mg g-1) in order to guide media selection in future experiments.

  11. Fetal and Maternal Absorbed Dose Estimates for Positron-Emitting Molecular Imaging Probes

    NARCIS (Netherlands)

    Xie, Tianwu; Zaidi, Habib

    2014-01-01

    PET and hybrid (PET/CT and PET/MR) imaging currently play a pivotal role in clinical diagnosis, staging and restaging, treatment, and surveillance of several diseases. As such, limiting the radiation exposure of special patients, such as pregnant women, from PET procedures is an important challenge

  12. Absorbed doses and radiation damage during the 11 years of LEP operation

    CERN Document Server

    Schönbacher, H

    2004-01-01

    During the 11 years of operation of the Large Electron Positron Collider (LEP), synchrotron radiation was emitted in the tunnel. This ionizing radiation induced degradation in organic insulators and structural materials, as well as in electronics. Annual dosimetric measurements have shown that the level of radiation increased with the ninth power of the beam energy. During the machine shut-downs and at the end of the operation, samples of rigid and flexible polymeric insulators (magnet-coil resins and cable insulations) were taken out and checked for their integrity. The test results are compared with the results obtained during the qualification of the materials, 12 to 15 years ago. At that time, lifetime predictions were done; they are now compared with the real time aged materials.

  13. Absorbed doses and radiation damage during the 11 years of LEP operation

    Science.gov (United States)

    Schönbacher, H.; Tavlet, M.

    2004-03-01

    During the 11 years of operation of the large electron-positron collider (LEP), synchrotron radiation was emitted in the tunnel. This ionizing radiation induced degradation in organic insulators and structural materials, as well as in electronics. Annual dosimetric measurements have shown that the level of radiation increased with the ninth power of the beam energy. During the machine shutdowns and at the end of the operation, samples of rigid and flexible polymeric insulators (magnet-coil resins and cable insulations) were taken out and checked for their integrity. The test results are compared with the results obtained during the qualification of the materials, 12-15 years ago. At that time, lifetime predictions were made; they are now compared with the real time-aged materials.

  14. An Energy Absorber with Force Modificator

    Institute of Scientific and Technical Information of China (English)

    SU Hao; ZHANG Xiaowei; YU Tongxi

    2006-01-01

    Thin-walled tubes are extensively applied in engineering,especially in vehicle structures to resist axial or traversal impact loads,for their excellent energy absorbing capacity.However,in the axial deformation mode,the force history has an extremely high peak force which may bring not only fatal injury to occupants but also damage to structures,cargo and environment.Aiming to develop energy absorbers with impact-force modificator,square metal tube with force modificator is investigated which can monitor the force-deformation history of the tube.A small device is designed to serve as an impact-force modificator,which introduces desired imperfections to the square tube just before the impact happens between the impactor and the tube,so as to reduce the peak force.Prototypes with various governing parameters were manufactured and tested both quasi-statically and dynamically to study the effects of these parameters on the characteristics of energy absorption.The results show that the force modificator can achieve the desired reduction of the peak force well whilst remaining the specific energy absorption capacity of the original square tube.With future improvements,it could be applied to vehicles or roadside safety hardware to mitigate the consequences produced by traffic accidents.

  15. Warm absorbers in active galactic nuclei

    CERN Document Server

    Reynolds, C S; Reynolds, C S; Fabian, A C

    1995-01-01

    Recent {\\it ASCA} observations confirm the presence of X-ray absorption due to partially ionized gas in many Seyfert 1 galaxies; the so-called warm absorber. Constraints on the location of the warm material are presented with the conclusion that this material lies at radii coincident with, or just outside, the broad-line region. The stability of this warm material to isobaric perturbations under the assumptions of thermal and photoionization equilibrium is also studied. It is shown that there is a remarkably small range of ionization parameter, \\xi, for which the warm absorber state is stable. The robustness of this result to changes in the shape of the primary continuum, the assumed density and optical depth is investigated. Given the constraints on the location and the stability properties of the material, several models for the environments of Seyfert nuclei are discussed. These attempt to explain the presence of significant amounts of partially ionized material. In particular, various models of the broad-...

  16. Possible Quantum Absorber Effects in Cortical Synchronization

    Science.gov (United States)

    Kämpf, Uwe

    The Wheeler-Feynman transactional "absorber" approach was proposed originally to account for anomalous resonance coupling between spatio-temporally distant measurement partners in entangled quantum states of so-called Einstein-Podolsky-Rosen paradoxes, e.g. of spatio-temporal non-locality, quantum teleportation, etc. Applied to quantum brain dynamics, however, this view provides an anticipative resonance coupling model for aspects of cortical synchronization and recurrent visual action control. It is proposed to consider the registered activation patterns of neuronal loops in so-called synfire chains not as a result of retarded brain communication processes, but rather as surface effects of a system of standing waves generated in the depth of visual processing. According to this view, they arise from a counterbalance between the actual input's delayed bottom-up data streams and top-down recurrent information-processing of advanced anticipative signals in a Wheeler-Feynman-type absorber mode. In the framework of a "time-loop" model, findings about mirror neurons in the brain cortex are suggested to be at least partially associated with temporal rather than spatial mirror functions of visual processing, similar to phase conjugate adaptive resonance-coupling in nonlinear optics.

  17. Randomized comparison of operator radiation exposure comparing transradial and transfemoral approach for percutaneous coronary procedures: Rationale and design of the minimizing adverse haemorrhagic events by TRansradial access site and systemic implementation of angioX - RAdiation Dose study (RAD-MATRIX)

    NARCIS (Netherlands)

    A. Sciahbasi (Alessandro); A. Calabrò (Anna); A. Sarandrea (Alessandro); S. Rigattieri (Stefano); F. Tomassini (Francesco); G. Sardella (Gennaro); D. Zavalloni (Dennis); B. Cortese (Bernardo); U. Limbruno (Ugo); M. Tebaldi (Matteo); A. Gagnor (Andrea); P. Rubartelli (Paolo); A. Zingarelli (Antonio); M. Valgimigli (Marco)

    2014-01-01

    textabstractBackground: Radiation absorbed by interventional cardiologists is a frequently under-evaluated important issue. Aim is to compare radiation dose absorbed by interventional cardiologists during percutaneous coronary procedures for acute coronary syndromes comparing transradial and transfe

  18. Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stynes, J. K.; Ihas, B.

    2012-04-01

    As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

  19. Nano-Composite Superfine Nickel Powder Double Absorbent Coating Designing

    Institute of Scientific and Technical Information of China (English)

    LU Yan-hong; WANG Zhi-hui; HUANG Dong-zhen; HU Chuan-xin; ZHANG Chen-jia; LI Wan-zhi; LIANG Wen-ting

    2004-01-01

    We adopt a definite procedure to compound traditional absorbing material-superfine powder nickel and nano -SiC powder to obtain the nano-composite nickel powder, then testing the absorbing speciality of the composite powder. In virtue of computer assistant designing, we apply double-deck absorbent structure to improve absorbent effect and widen wave band. The experiment indicated that it is possible to achieve the anticipative object to improve the absorbing capability by adopting nano-composite absorbing material, but each component of the composite material must have matched electromagnetic parameter with another. For matching double-coating structure, it ought to modulate the correlativity of each factor to achieve the most matching in order to optimise the absorbent speciality.

  20. Radiation doses and risks from internal emitters

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, John [Health Protection Agency, Radiation Protection Division, CRCE, Chilton, Didcot, Oxon OX11 0RQ (United Kingdom); Day, Philip [School of Chemistry, University of Manchester, Manchester M13 9PL (United Kingdom)], E-mail: john.harrison@hpa.org.uk, E-mail: philip.day@manchester.ac.uk

    2008-06-01

    This review updates material prepared for the UK Government Committee Examining Radiation Risks from Internal Emitters (CERRIE) and also refers to the new recommendations of the International Commission on Radiological Protection (ICRP) and other recent developments. Two conclusions from CERRIE were that ICRP should clarify and elaborate its advice on the use of its dose quantities, equivalent and effective dose, and that more attention should be paid to uncertainties in dose and risk estimates and their implications. The new ICRP recommendations provide explanations of the calculation and intended purpose of the protection quantities, but further advice on their use would be helpful. The new recommendations refer to the importance of understanding uncertainties in estimates of dose and risk, although methods for doing this are not suggested. Dose coefficients (Sv per Bq intake) for the inhalation or ingestion of radionuclides are published as reference values without uncertainty. The primary purpose of equivalent and effective dose is to enable the summation of doses from different radionuclides and from external sources for comparison with dose limits, constraints and reference levels that relate to stochastic risks of whole-body radiation exposure. Doses are calculated using defined biokinetic and dosimetric models, including reference anatomical data for the organs and tissues of the human body. Radiation weighting factors are used to adjust for the different effectiveness of different radiation types, per unit absorbed dose (Gy), in causing stochastic effects at low doses and dose rates. Tissue weighting factors are used to take account of the contribution of individual organs and tissues to overall detriment from cancer and hereditary effects, providing a simple set of rounded values chosen on the basis of age- and sex-averaged values of relative detriment. While the definition of absorbed dose has the scientific rigour required of a basic physical quantity

  1. Active packaging using ethylene absorber to extend shelf-life

    Energy Technology Data Exchange (ETDEWEB)

    Ponce, Patricia; Carbonari, Guilherme L.R.; Lugao, Ademar B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: patponce@iq.usp.br, e-mail: guilacaz@uol.com.br, e-mail: ablugao@ipen.br

    2009-07-01

    Ethylene gas is a plant hormone which is produced by fruits and vegetables during ripening and it is also found in the environment. It plays an essential role in normal ripening, but excessive exposure can radically reduce the shelf-life of the product, in some cases inducing undesirable reactions such as development of bitter flavors and loss of chlorophyll (yellowing of greens). The objectives of our work were: to test an active packaging of polyvinyl alcohol (PVA) for apple stored; to test the effect of ethylene absorber agent, impregnated in plastic film, to reduce decay of fresh apple; to study the influence of radiation on the barrier properties, mechanical properties and biodegradability of PVA films. This study evaluated the effect of coating produced from PVA and polyol (glycerol and sorbitol) as plasticizer on apple conservation (75 deg F (24 deg C); 70%RH). The coated product was analyzed for mass loss, color alterations and fungi. The PVA films were produced by casting process (dehydration of a filmogenic solution on Petriplastic dishes) and were irradiated at low doses of 2, 5 and 10 kGy, commonly used in food irradiation. The resulting films were transparent and homogeneous. The active packaged fruits presented higher acceptance, lower microbiological growth, less alterations in acidity, lower weight loss rate during the storage time and an extended shelf-life as compared to the control fruits (without plastic films). (author)

  2. Dose spectra from energetic particles and neutrons

    Science.gov (United States)

    Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

    2013-10-01

    spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

  3. A chiral microwave absorbing absorbent of Fe–CoNiP coated on spirulina

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang, E-mail: xuyonggang221@163.com [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Yuan, Liming [Science and Technology on Electromagnetic Scattering Laboratory, Shanghai, 200438 (China); Zhang, Deyuan [School of Mechanical Engineering and Automation, Beihang University, Beijing, 100191 (China)

    2015-11-15

    A chiral bio-absorbent of Fe–CoNiP coated on the spirulina was fabricated by the electroless and chemical vapor decomposition. The scanning electron microscopy (SEM) was used to evaluate the spirulina cells particle morphology. X-ray diffraction (XRD) patterns were done to analyze the particle crystal grain structure. The permittivity and permeability was measured by a vector network analyzer in frequency 8–18 GHz, and the reflection loss (RL) was calculated. The results showed the carbonyl iron particles (CIPs) and CoNiP were bonded to the spirulina surface, the permittivity and permeability could be enlarged as Fe films coated on the particles compared with the CoNiP spirulina, it was attributed to the excellent electromagnetic property of CIPs. The chiral Fe–CoNiP composites had a better absorbing property at 8–18 GHz than the CoNiP spirulina composite, the RL was −16.26 dB at 10.48 GHz, the absorbing band was 9.5–11.5 GHz of RL less than −10 dB, which indicated the Fe–CoNiP spirulina could be an effective absorbent used in 8–18 GHz. - Highlights: • Absorbers filled with Fe–CoNiP coating on the spirulina were fabricated. • The permittivity and permeability increased as CIPs coated. • The Fe material enhanced the electromagnetic property. • The spirulina coated Fe–CoNiP was effective in 8–18 GHz.

  4. Assessment of fetal radiation dose to patients and staff in diagnostic radiology

    Energy Technology Data Exchange (ETDEWEB)

    Osei, E.K

    2000-07-01

    A major source of uncertainty in the estimation of fetal absorbed radiation dose is the influence of fetal size and position as these change with gestational age. Consequently, dose to the fetus is related to gestational age. Most studies of fetal dose estimation during pregnancy assume that the uterus dose is equal to fetal dose. These dose estimates do not take account of gestational age and individual fetal depth, factors which are significant when calculating dose. To establish both positional and size data for estimation of fetal absorbed dose from radiological examinations, the depths from the mother's anterior surface to the mid-line of the fetal head and abdomen were measured from ultrasound scans in 215 pregnant women. Depths were measured along a ray path projected in the anterior-posterior direction from the mother's abdomen. The fetal size was estimated from measurements of the fetal abdominal and head circumference, femur length and the biparietal diameter. The effects of fetal presentation, maternal bladder volume, placenta location, gestational age and maternal AP thickness on fetal depth and size were analysed. A Monte Carlo (MC) model was developed, and used to derive factors for converting dose-area product and free-in-air entrance surface dose from medical exposure of a pregnant patient to absorbed dose to the uterus/embryo, and for converting uterus dose to fetal dose in the later stages of pregnancy. Also presented are factors for converting thermoluminescence dosimeter reading from occupational exposure of a pregnant worker to equivalent dose to the fetus. The MC model was verified experimentally by direct measurement of uterus depth dose in a female Rando phantom, and also by comparison with other experimental work and MC results in the literature. The application of the various conversion factors is demonstrated by a review of the dose estimation process in 50 cases of fetal irradiation from medical exposures. (author)

  5. Skin interaction with absorbent hygiene products.

    Science.gov (United States)

    Runeman, Bo

    2008-01-01

    Skin problems due to the use of absorbent hygiene products, such as diapers, incontinence pads, and feminine sanitary articles, are mostly due to climate or chafing discomfort. If these conditions are allowed to prevail, these may develop into an irritant contact dermatitis and eventually superficial skin infections. Skin humidity and aging skin are among the most significant predisposing and aggravating factors for dermatitis development. Improved product design features are believed to explain the decline in observed diaper dermatitis among infants. Where adult incontinence-related skin problems are concerned, it is very important to apply a holistic perspective to understand the influences due to the individual's incontinence level and skin condition, as well as the hygiene and skin care measures provided. Individuals with frail, sensitive skin or with skin diseases may preferably have to use high-quality products, equipped with superabsorbent polymers and water vapor-permeable back sheets, to minimize the risk of skin complications.

  6. Post-treatments of Super Absorbent Polymer

    Institute of Scientific and Technical Information of China (English)

    LIU Song; ZHOU Xiang; XING Zhi-qi

    2002-01-01

    Properties of high absorbency and modulus (gel rength) were both needed in applications of superabsorbent polymer (SAP). Generally, the absorption characteristic and gel strength reach a crossover point for a given system. Beyond this point, a given property will show improvement at the expense of another property. To synthesize SAP with properties superior to this optimum value, further modification in the process becomes essential. In our post-treatment modification of superabsorbent polymer, neither the variety of the crosslinkers, nor their amount was found the effective factors to the polymer performance, but the liquor ratio of the treating liquid to polymer. The combination of the chemical treating and heat-treating method was also explored. But this didn't put any positive effect on SAP's properties.

  7. Hot Carrier extraction with plasmonic broadband absorbers

    CERN Document Server

    Ng, Charlene; Dligatch, Svetlana; Roberts, Ann; Davis, Timothy J; Mulvaney, Paul; Gomez, Daniel E

    2016-01-01

    Hot charge carrier extraction from metallic nanostructures is a very promising approach for applications in photo-catalysis, photovoltaics and photodetection. One limitation is that many metallic nanostructures support a single plasmon resonance thus restricting the light-to-charge-carrier activity to a spectral band. Here we demonstrate that a monolayer of plasmonic nanoparticles can be assembled on a multi-stack layered configuration to achieve broad-band, near-unit light absorption, which is spatially localised on the nanoparticle layer. We show that this enhanced light absorbance leads to $\\sim$ 40-fold increases in the photon-to-electron conversion efficiency by the plasmonic nanostructures. We developed a model that successfully captures the essential physics of the plasmonic hot-electron charge generation and separation in these structures. This model also allowed us to establish that efficient hot carrier extraction is limited to spectral regions where the photons possessing energies higher than the S...

  8. Ultrathin microwave absorber based on metamaterial

    Science.gov (United States)

    Kim, Y. J.; Yoo, Y. J.; Hwang, J. S.; Lee, Y. P.

    2016-11-01

    We suggest that ultrathin broadband metamaterial is a perfect absorber in the microwave regime by utilizing the properties of a resistive sheet and metamaterial. Meta-atoms are composed of four-leaf clover-shape metallic patterns and a metal plane separated by three intermediate resistive sheet layers between four dielectric layers. We interpret the absorption mechanism of the broadband by using the distribution of surface currents at specific frequencies. The simulated absorption was over 99% in 1.8-4.2 GHz. The corresponding experimental absorption was also over 99% in 2.62-4.2 GHz; however, the absorption was slightly lower than 99% in 1.8-2.62 GHz because of the sheet resistance and the changed values for the dielectric constant. Furthermore, it is independent of incident angle. The results of this research indicate the possibility of applications, due to the suppression of noxious exposure, in cell phones, computers and microwave equipments.

  9. Corundum-based transparent infrared absorbers

    KAUST Repository

    Schwingenschlögl, Udo

    2009-10-01

    Hypothetical corundum-based compounds are studied by electronic structure calculations. One quarter of the Al atoms in Al2O3 is replaced by a 3d transition metal from the M = Ti, ..., Zn (d1, ..., d9) series. Structure optimisations are performed for all the M-Al2O3 compounds and the electronic states are evaluated. Due to the M substitutes, narrow partially filled bands are formed at the Fermi energy. Beyond, for M = Ni and M = Cu the optical properties of Al2O3 in the visible range are conserved, while for M = Ti, ..., Co the systems form high accuracy optical filters. Since the compounds absorb the infrared radiation, the M = Ni and M = Cu systems are good candidates for heat-protective coatings. © 2009 Elsevier B.V. All rights reserved.

  10. PLD-grown thin film saturable absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Tellkamp, Friedjof

    2012-11-01

    The subject of this thesis is the preparation and characterization of thin films made of oxidic dielectrics which may find their application as saturable absorber in passively Q-switched lasers. The solely process applied for fabrication of the thin films was the pulsed laser deposition (PLD) which stands out against other processes by its flexibility considering the composition of the systems to be investigated. Within the scope of this thesis the applied saturable absorbers can be divided into two fundamentally different kinds of functional principles: On the one hand, saturable absorption can be achieved by ions embedded in a host medium. Most commonly applied bulk crystals are certain garnets like YAG (Y{sub 3}Al{sub 5}O{sub 12}) or the spinel forsterite (Mg{sub 2}SiO{sub 4}), in each case with chromium as dopant. Either of these media was investigated in terms of their behavior as PLD-grown saturable absorber. Moreover, experiments with Mg{sub 2}GeO{sub 4}, Ca{sub 2}GeO{sub 4}, Sc{sub 2}O{sub 3}, and further garnets like YSAG or GSGG took place. The absorption coefficients of the grown films of Cr{sup 4+}:YAG were determined by spectroscopic investigations to be one to two orders of magnitude higher compared to commercially available saturable absorbers. For the first time, passive Q-switching of a Nd:YAG laser at 1064 nm with Cr{sup 4+}:YAG thin films could be realized as well as with Cr:Sc{sub 2}O{sub 3} thin films. On the other hand, the desirable effect of saturable absorption can also be generated by quantum well structures. For this purpose, several layer system like YAG/LuAG, Cu{sub 2}O/MgO, and ZnO/corumdum were investigated. It turned out that layer systems with indium oxide (In{sub 2}O{sub 3}) did not only grew in an excellent way but also showed up a behavior regarding their photo luminescence which cannot be explained by classical considerations. The observed luminescence at roughly 3 eV (410 nm) was assumed to be of excitonic nature and its

  11. Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Calcina, Carmen S Guzman [Departamento de FIsica e Matematica, FFCLRP, Universidade de Sao Paulo, Av Bandeirantes 3900, 14040-901, Ribeirao Preto, SP (Brazil); Almeida, Adelaide de [Departamento de FIsica e Matematica, FFCLRP, Universidade de Sao Paulo, Av Bandeirantes 3900, 14040-901, Ribeirao Preto, SP (Brazil); Rocha, Jose R Oliveira [Setor de FIsica Medica-CEB-UNICAMP e Setor de Radioterapia-CAISM-UNICAMP (Brazil); Abrego, Felipe Chen [Departamento de FIsica e Matematica, FFCLRP, Universidade de Sao Paulo, Av Bandeirantes 3900, 14040-901, Ribeirao Preto, SP (Brazil); Baffa, Oswaldo [Departamento de FIsica e Matematica, FFCLRP, Universidade de Sao Paulo, Av Bandeirantes 3900, 14040-901, Ribeirao Preto, SP (Brazil)

    2005-03-21

    Source positioning close to the tumour in high dose rate (HDR) brachytherapy is not instantaneous. An increment of dose will be delivered during the movement of the source in the trajectory to its static position. This increment is the transit dose, often not taken into account in brachytherapeutic treatment planning. The transit dose depends on the prescribed dose, number of treatment fractions, velocity and activity of the source. Combining all these factors, the transit dose can be 5% higher than the prescribed absorbed dose value (Sang-Hyun and Muller-Runkel, 1994 Phys. Med. Biol. 39 1181-8, Nath et al 1995 Med. Phys. 22 209-34). However, it cannot exceed this percentage (Nath et al 1995). In this work, we use the alanine-EPR (electron paramagnetic resonance) dosimetric system using analysis of the first derivative of the signal. The transit dose was evaluated for an HDR system and is consistent with that already presented for TLD dosimeters (Bastin et al 1993 Int. J. Radiat. Oncol. Biol. Phys. 26 695-702). Also using the same dosimetric system, the radial dose function, used to evaluate the geometric dose degradation around the source, was determined and its behaviour agrees better with those obtained by Monte Carlo simulations (Nath et al 1995, Williamson and Nath 1991 Med. Phys. 18 434-48, Ballester et al 1997 Med. Phys. 24 1221-8, Ballester et al 2001 Phys. Med. Biol. 46 N79-90) than with TLD measurements (Nath et al 1990 Med. Phys. 17 1032-40)

  12. Flexor Tenorrhaphy Using Absorbable Suture Materials

    Directory of Open Access Journals (Sweden)

    Hyung Joo Kang

    2012-07-01

    Full Text Available Background Nonabsorbable sutures are favorable for repairing flexor tendons. However,absorbable sutures have performed favorably in an animal model.Methods Two-strand sutures using the interlocking modified Kessler method with polydioxanoneabsorbable sutures 4-0 were used to repair completely ruptured flexor tendons in 55 fingersfrom 41 consecutive patients. The medical records of average 42 follow up weeks were analyzedretrospectively. The data analyzed using the chi-squared test, and Fisher’s exact test was used forpostoperative complications. The results were compared with those of other studies.Results Among the index, middle, ring, and little fingers were injured in 9, 17, 16, and13 fingers, respectively. The injury levels varied from zone 1 to 5. Of the 55 digits in ourstudy, there were 26 (47% isolated flexor digitorum profundus (FDP injuries and 29 (53%combined FDP and with flexor digitorum superficialis injuries. Pulley repair was also conducted.Concomitant injuries of blood vessels and nerves were found in 17 patients (23 fingers; nerveinjuries occurred in 5 patients (10 fingers. Two patients had ruptures (3.6%, and one patienthad two adhesions (3.6%. Using the original Strickland criteria, all the patients were assessedto be excellent or good. Also, fibrosis and long-term foreign body tissue reactions such as stitchgranuloma were less likely occurred in our study. Compared to the Cullen’s report that usednonabsorbable sutures, there was no significant difference in the rupture or adhesion rates.Conclusions Therefore, this study suggests that appropriate absorbable core sutures can beused safely for flexor tendon repairs.

  13. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Ary A. [Universidade Estadual de Londrina-Depto de Fisica, Rodovia Celso Garcia Cid, km 38, 086051-990 Londrina (Brazil); Vieira, Jose M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Hamada, Margarida M. [Instituto de Pesquisas Energeticas e Nucleares-IPEN/CNEN-SP, Prof. Lineu Prestes, 2242-Cidade Universitaria, 05508-900 Sao Paulo (Brazil)], E-mail: mmhamada@ipen.br

    2010-04-15

    A 1 cm{sup 3} cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a {sup 60}Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  14. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators.

    Science.gov (United States)

    Rodrigues, Ary A; Vieira, Jose M; Hamada, Margarida M

    2010-01-01

    A 1 cm(3) cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a (60)Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  15. Polyvinyl butyral films containing leuco-malachite green as low-dose dosimeters

    Science.gov (United States)

    Mai, Hoang Hoa; Solomon, H. M.; Taguchi, M.; Kojima, T.

    2008-04-01

    Thin films containing leuco-malachite green (LMG) dye in polyvinyl butyral (PVB) have been developed for dose measurements of a few hundreds Gy level. The film shows significant color change in the visible range, and the sensitivity of the film to absorbed dose was enhanced by addition of chloride-containing compounds, such as chloral hydrate or 2,2,2-trichloroethanol. The film is suitable as dosimeters for dose measurements, e.g. in food irradiation and environmental protection.

  16. Polyvinyl butyral films containing leuco-malachite green as low-dose dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Hoang Hoa Mai [Institute for Nuclear Science Technique, Vietnam Atomic Energy Commission (VAEC), 59 Ly Thuong Kiet, Hanoi (Viet Nam); Solomon, H.M. [Philippine Nuclear Research Institute (PNRI), Commonwealth Avenue, Diliman Quezon City (Philippines); Taguchi, M. [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki-shi. Gunma 370-1292 (Japan); Kojima, T. [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki-shi. Gunma 370-1292 (Japan)], E-mail: kojima.takuji@jaea.go.jp

    2008-04-15

    Thin films containing leuco-malachite green (LMG) dye in polyvinyl butyral (PVB) have been developed for dose measurements of a few hundreds Gy level. The film shows significant color change in the visible range, and the sensitivity of the film to absorbed dose was enhanced by addition of chloride-containing compounds, such as chloral hydrate or 2,2,2-trichloroethanol. The film is suitable as dosimeters for dose measurements, e.g. in food irradiation and environmental protection.

  17. Heat and mass transfer characteristics of a small helical absorber

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung-In [College of Engineering, School of Mechanical Engineering, Pukyong National University, San 100, Yongdang-dong, Nam-gu, Pusan 608-739 (Korea, Republic of); Kwon, Oh-Kyung [KITECH, 35-3 Hongchon-ri, Ipjang-meon, Chonan, Chungnam 330-825 (Korea, Republic of); Bansal, P.K. [Department of Mechanical Engineering, The University of Auckland, Private bag 92019, Auckland (New Zealand); Moon, Choon-Geun; Lee, Ho-Saeng [Department of Refrigeration and Air-conditioning Engineering, Graduate School, Pukyong National University, San 100, Yongdang-dong, Nam-gu, Pusan 608-739 (Korea, Republic of)

    2006-02-01

    This paper presents experimental results of heat and mass transfer investigation of the falling film absorber (with strong lithium bromide solution) for a small household absorption chiller/heater. Various components (e.g. low temperature generator, absorber and evaporator) were arranged concentrically in cylindrical form such that the helical-arrangement of the heat exchangers allowed the system to be more compact than the conventional system. Measurements from the helical absorber were compared with data from the literature. The comparison revealed that the heat and mass transfer performance of the helical absorber tube is similar to the existing tube bundle absorber. As a result, the proposed helical absorber shows a good potential due its reduced size and weight for the future designs of small capacity absorption chillers/heaters. (author)

  18. Large area bismuth absorbers for X-ray microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Vaillancourt, J.E. E-mail: vaillancourt@wisp.physics.wisc.edu; Allen, C.A.; Brekosky, R.; Dosaj, A.; Galeazzi, M.; Kelley, R.; Liu, D.; McCammon, D.; Porter, F.S.; Rocks, L.E.; Sanders, W.T.; Stahle, C.K

    2004-03-11

    Two challenges facing the use of large area (2 mmx2 mm) bismuth absorbers for microcalorimetry are uncertainties in the heat capacity of bismuth and the effects of lateral heat conduction and position dependence due to the absorber's large size. We have measured the heat capacity of three Bi samples to be 0.3-0.6 J K{sup -1} m{sup -3} at 100 mK. These absorbers also exhibit response variations as phonons created by an X-ray event at an absorber edge will take longer to propagate to the thermometer attachment point than those at the absorber center. This effect may degrade the detector's energy resolution if the propagation time is not very short compared to the thermometer time constant. We show that the response of the largest absorber varies by {approx}4% across its area.

  19. Errors and Uncertainties in Dose Reconstruction for Radiation Effects Research

    Energy Technology Data Exchange (ETDEWEB)

    Strom, Daniel J.

    2008-04-14

    Dose reconstruction for studies of the health effects of ionizing radiation have been carried out for many decades. Major studies have included Japanese bomb survivors, atomic veterans, downwinders of the Nevada Test Site and Hanford, underground uranium miners, and populations of nuclear workers. For such studies to be credible, significant effort must be put into applying the best science to reconstructing unbiased absorbed doses to tissues and organs as a function of time. In many cases, more and more sophisticated dose reconstruction methods have been developed as studies progressed. For the example of the Japanese bomb survivors, the dose surrogate “distance from the hypocenter” was replaced by slant range, and then by TD65 doses, DS86 doses, and more recently DS02 doses. Over the years, it has become increasingly clear that an equal level of effort must be expended on the quantitative assessment of uncertainty in such doses, and to reducing and managing uncertainty. In this context, this paper reviews difficulties in terminology, explores the nature of Berkson and classical uncertainties in dose reconstruction through examples, and proposes a path forward for Joint Coordinating Committee for Radiation Effects Research (JCCRER) Project 2.4 that requires a reasonably small level of effort for DOSES-2008.

  20. Local Structure Analysis of Materials for Solar Cell Absorber Layer

    OpenAIRE

    Jewell, Leila Elizabeth

    2016-01-01

    This dissertation examines solar cell absorber materials that have the potential to replace silicon in solar cells, including several copper-based sulfides and perovskites. Earth-abundant absorbers such as these become even more cost-effective when used in a nanostructured solar cell. Atomic layer deposition (ALD) and chemical vapor deposition (CVD) deposit highly conformal films and hence are important tools for developing extremely thin absorber solar cells with scalability. Thus, the prima...

  1. Design and Implementation of a Regenerative Shock Absorber

    OpenAIRE

    Maravandi, Amir

    2015-01-01

    In this thesis, the development of a novel regenerative shock absorber sized for a passengercar suspension system is studied. In the first phase, DC and AC rotary machines along with charging circuits, to be used in the energy conversion stage of the proposed shock absorber are analyzed. In this analysis, the rotary damping coefficients provided by these systems are obtained following by experimental results.In the second phase, the development of a novel regenerative shock absorber in a proo...

  2. Effect of UV absorbers on UV-induced mutagenesis in E. coli B/r

    Energy Technology Data Exchange (ETDEWEB)

    Shimoi, Kayoko; Nakamura, Yoshiyuki; Tomita, Isao

    1988-01-01

    Effects of cosmetic UV absorbers on UV-induced mutagenesis in E. coli B/r strains were studied. Among 8 substances tested, cinoxate (2-ethoxyethyl p-methoxycinnamate) enhanced UV (254 nm)-induced mutation at non-lethal toxic doses. This adverse effect was also observed when the mid and near-UV (295 nm - 400 nm) irradiated cells of WP2 were used. This effect, however, was not observed in WP2s uvrA, a DNA excision repair deficient strain of E. coli B/r. It is thus assumed that cinoxate inhibited DNA excision repair system and consequently increased UV-induced mutation.

  3. Light-absorbing impurities in Arctic snow

    Directory of Open Access Journals (Sweden)

    S. J. Doherty

    2010-08-01

    Full Text Available Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983–1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 2005–2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland ice sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study.

    The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC, the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow: Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, Subarctic Canada 14, Svalbard 13, Northern Norway 21, Western Arctic Russia 26, Northeastern Siberia 17. Concentrations are more variable in the European Arctic than in Arctic Canada or the Arctic Ocean, probably because of the proximity

  4. Optimal active vibration absorber - Design and experimental results

    Science.gov (United States)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1993-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  5. Optimal active vibration absorber: Design and experimental results

    Science.gov (United States)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1992-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  6. ABSORBENCY CHARACTERISTICS OF PESHTAMALS: TRADITIONAL TURKISH WOVEN CLOTHES

    Directory of Open Access Journals (Sweden)

    KESKIN Reyhan

    2014-05-01

    Full Text Available Absorbency of textiles is defined as the ability of taking in a fluid in the manner of a sponge. Absorbency is required for comfort properties in so me clothes such as sportswear and underwear clothing, for drying properties in napkins, towels and bathrobes, for health concerns in some medical textiles such as bandages, gauze and absorbent cotton, and for cleaning properties in washclothes and mops. In this study five different fabric samples (three woven 100% cotton fabrics A, B and P respectively at plain, twill, and peshtamal weaving patterns and two 100% cotton terry towels T1 and T2 were tested. The absorbency properties of the samples were evaluated according to the droplet test, sinking time test and wicking height tests (pottasium chromate test. Peshtamal samples showed better absorbency results than plain and twill weaves and lower but close results to towel samples according to the droplet test, sinking time test and wicking height tests. The absorbency properties of peshtamals showed results close to towel samples. The void content of peshtamals is higher than plain and twill samples but closer and lower than towel samples. The good absorbency results of peshtamals might be due to the void content of peshtamals which is higher than plain and twill samples but closer and lower than towel samples. Peshtamals which are good in absorbency and light in weight might be used widespreadly in daily life for their high absorbency, and on travel for weight saving purposes.

  7. Simulated mixed absorbers and effective atomic numbers for attenuation

    Indian Academy of Sciences (India)

    K Karunakaran Nair; N Ramachandran; K K Abdullah; K M Varier

    2006-09-01

    The total -ray interaction crosss-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for -ray absorption under narrow beam good geometry set-up. The measurements were taken for the combination of metallic absorbers like aluminium, copper, lead and mercury and also for the simulated absorbers by rotating the targets. ORTEC HPGe and NaI(Tl) detectors were used for detection of -rays.The experimental results compare favourably with theoretical values derived from XCOM package and suggest the usefulness of the concept of effective atomic numbers and the utility of the rotating absorbers technique.

  8. Radiation dose study in nuclear medicine using GATE

    Science.gov (United States)

    Aguwa, Kasarachi

    Dose as a result of radiation exposure is the notion generally used to disclose the imparted energy in a volume of tissue to a potential biological effect. The basic unit defined by the international system of units (SI system) is the radiation absorbed dose, which is expressed as the mean imparted energy in a mass element of the tissue known as "gray" (Gy) or J/kg. The procedure for ascertaining the absorbed dose is complicated since it involves the radiation transport of numerous types of charged particles and coupled photon interactions. The most precise method is to perform a full 3D Monte Carlo simulation of the radiation transport. There are various Monte Carlo toolkits that have tool compartments for dose calculations and measurements. The dose studies in this thesis were performed using the GEANT4 Application for Emission Tomography (GATE) software (Jan et al., 2011) GATE simulation toolkit has been used extensively in the medical imaging community, due to the fact that it uses the full capabilities of GEANT4. It also utilizes an easy to-learn GATE macro language, which is more accessible than learning the GEANT4/C++ programming language. This work combines GATE with digital phantoms generated using the NCAT (NURBS-based cardiac-torso phantom) toolkit (Segars et al., 2004) to allow efficient and effective estimation of 3D radiation dose maps. The GATE simulation tool has developed into a beneficial tool for Monte Carlo simulations involving both radiotherapy and imaging experiments. This work will present an overview of absorbed dose of common radionuclides used in nuclear medicine and serve as a guide to a user who is setting up a GATE simulation for a PET and SPECT study.

  9. Computational assessment of effective dose and patient specific doses for kilovoltage stereotactic radiosurgery of wet age-related macular degeneration

    Science.gov (United States)

    Hanlon, Justin Mitchell

    Age-related macular degeneration (AMD) is a leading cause of vision loss and a major health problem for people over the age of 50 in industrialized nations. The current standard of care, ranibizumab, is used to help slow and in some cases stabilize the process of AMD, but requires frequent invasive injections into the eye. Interest continues for stereotactic radiosurgery (SRS), an option that provides a non-invasive treatment for the wet form of AMD, through the development of the IRay(TM) (Oraya Therapeutics, Inc., Newark, CA). The goal of this modality is to destroy choroidal neovascularization beneath the pigment epithelium via delivery of three 100 kVp photon beams entering through the sclera and overlapping on the macula delivering up to 24 Gy of therapeutic dose over a span of approximately 5 minutes. The divergent x-ray beams targeting the fovea are robotically positioned and the eye is gently immobilized by a suction-enabled contact lens. Device development requires assessment of patient effective dose, reference patient mean absorbed doses to radiosensitive tissues, and patient specific doses to the lens and optic nerve. A series of head phantoms, including both reference and patient specific, was derived from CT data and employed in conjunction with the MCNPX 2.5.0 radiation transport code to simulate treatment and evaluate absorbed doses to potential tissues-at-risk. The reference phantoms were used to evaluate effective dose and mean absorbed doses to several radiosensitive tissues. The optic nerve was modeled with changeable positions based on individual patient variability seen in a review of head CT scans gathered. Patient specific phantoms were used to determine the effect of varying anatomy and gaze. The results showed that absorbed doses to the non-targeted tissues were below the threshold levels for serious complications; specifically the development of radiogenic cataracts and radiation induced optic neuropathy (RON). The effective dose

  10. Radiation doses to aquatic organisms from natural radionuclides.

    Science.gov (United States)

    Brown, J E; Jones, S R; Saxén, R; Thørring, H; Vives i Batlle, J

    2004-12-01

    A framework for protection of the environment is likely to require a methodology for assessing dose rates arising from naturally occurring radionuclides. This paper addresses this issue for European aquatic environments through a process of (a) data collation, mainly with respect to levels of radioactivity in water sediments and aquatic flora and fauna, (b) the use of suitable distribution coefficients, concentration factors and global data where data gaps are present and (c) the utilisation of a reference organism approach whereby a finite number of suitable geometries are selected to allow dose per unit concentration factors to be derived and subsequent absorbed dose calculations (weighted or unweighted) to be made. The majority of the calculated absorbed dose, for both marine and freshwater organisms, arises from internally incorporated alpha emitters, with 210Po and 226Ra being the major contributors. Calculated doses are somewhat higher for freshwater compared to marine organisms, and the range of doses is also much greater. This reflects both the much greater variability of radionuclide concentrations in freshwater as compared to seawater, and also variability or uncertainty in concentration factor values. This work has revealed a number of substantial gaps in published empirical data especially for European aquatic environments.

  11. Light absorbing carbon emissions from commercial shipping

    Science.gov (United States)

    Lack, Daniel; Lerner, Brian; Granier, Claire; Baynard, Tahllee; Lovejoy, Edward; Massoli, Paola; Ravishankara, A. R.; Williams, Eric

    2008-07-01

    Extensive measurements of the emission of light absorbing carbon aerosol (LAC) from commercial shipping are presented. Vessel emissions were sampled using a photoacoustic spectrometer in the Gulf of Mexico region. The highest emitters (per unit fuel burnt) are tug boats, thus making significant contributions to local air quality in ports. Emission of LAC from cargo and non cargo vessels in this study appears to be independent of engine load. Shipping fuel consumption data (2001) was used to calculate a global LAC contribution of 133(+/-27) Ggyr-1, or ~1.7% of global LAC. This small fraction could have disproportionate effects on both air quality near port areas and climate in the Arctic if direct emissions of LAC occur in that region due to opening Arctic sea routes. The global contribution of this LAC burden was investigated using the MOZART model. Increases of 20-50 ng m-3 LAC (relative increases up to 40%) due to shipping occur in the tropical Atlantic, Indonesia, central America and the southern regions of South America and Africa.

  12. Absorber Coatings for Mid-Infrared Astrophysics

    Science.gov (United States)

    Baker, Dahlia Anne; Wollack, Edward; Rostem, Karwan

    2017-01-01

    Control over optical response is an important aspect of instrument design for astrophysical imaging. Here we consider a mid-infrared absorber coating proposed for use on HIRMES (High Resolution Mid-Infrared Spectrometer), a cryogenic spectrometer which will fly on the SOFIA (Stratospheric Observatory for Infrared Astronomy) aircraft. The aim of this effort is to develop an absorptive coating for the 20-200 microns spectral range based on a graphene loaded epoxy binder (Epotek 377H) and glass microsphere scatterers (3M K1). The coatings electromagnetic response was modeled using a Matlab script and the glass microspheres were characterized by the measured size distribution, the dielectric constant, and the filling fraction. Images of the microspheres taken by a microscope were used to determine the size distribution with an ImageJ particle analysis program. Representative test samples for optical evaluation were fabricated for characterization via infrared Fourier transform spectroscopy. The optical tests will determine the material’s absorptance and reflectance. These test results will be compared to the modeled response.

  13. Semiconductor nanowire optical antenna solar absorbers.

    Science.gov (United States)

    Cao, Linyou; Fan, Pengyu; Vasudev, Alok P; White, Justin S; Yu, Zongfu; Cai, Wenshan; Schuller, Jon A; Fan, Shanhui; Brongersma, Mark L

    2010-02-10

    Photovoltaic (PV) cells can serve as a virtually unlimited clean source of energy by converting sunlight into electrical power. Their importance is reflected in the tireless efforts that have been devoted to improving the electrical and structural properties of PV materials. More recently, photon management (PM) has emerged as a powerful additional means to boost energy conversion efficiencies. Here, we demonstrate an entirely new PM strategy that capitalizes on strong broad band optical antenna effects in one-dimensional semiconductor nanostructures to dramatically enhance absorption of sunlight. We show that the absorption of sunlight in Si nanowires (Si NWs) can be significantly enhanced over the bulk. The NW's optical properties also naturally give rise to an improved angular response. We propose that by patterning the silicon layer in a thin film PV cell into an array of NWs, one can boost the absorption for solar radiation by 25% while utilizing less than half of the semiconductor material (250% increase in the light absorption per unit volume of material). These results significantly advance our understanding of the way sunlight is absorbed by one-dimensional semiconductor nanostructures and provide a clear, intuitive guidance for the design of efficient NW solar cells. The presented approach is universal to any semiconductor and a wide range of nanostructures; as such, it provides a new PV platform technology.

  14. Effects of Root-Growing Space on Its Absorbing Characteristics

    Institute of Scientific and Technical Information of China (English)

    SONG Hai-xing; LI Sheng-xiu

    2003-01-01

    Influences of root-growing space of maize upon root physiological characteristics, nutrient uptake and crop yields were studied under conditions with and without supply of water and N. Results showed that limitation of the root-growing space greatly affected root growth, decreased total root-absorbing area and TTC-reductive amounts. However, it obviously increased the root active-absorbing area, specific absorbing area (absorbing area per gram root weight) and specific active-absorbing area (actively absorbing area per gram root weight) in addition to promoting the TTC-reductive intensity. This clearly showed that plants were not passively tolerant to stress, but actively regulated their physiological metabolic processes, and strengthened their absorbing ability to increase water and nutrient uptake so that root injury by the environmental stress could be reduced. Supply of water and N stimulated root growth, increased root-absorbing area and activity, promoted nutrient uptake, and therefore increased crop yield and decreased the detrimental effects resulting from the limitation of roots-growing space.

  15. Preparation of Superabsorbent Polymers with Increased Saline Absorbency

    Institute of Scientific and Technical Information of China (English)

    LIU Song; JIN Yi-fen; ZHOU Xiang

    2002-01-01

    Superabsorbent having enhanced absorbency of 0.9%NaCl solution was synthesized on one basis of incorporating zwitterionic (sulfobetaine) monomer into the previous monomer mixture, which comprises ionic (AA) and nonionic monomers, and another basis of introducing inorganic salt B. As far as saline absorbency is concerned, introduction of inorganic salt B is more useful than the sulfobetaine monomer.

  16. A blast absorber test: measurement and model results

    NARCIS (Netherlands)

    Eerden, F.J.M. van der; Berg, F. van den; Hof, J. van 't; Arkel, E. van

    2006-01-01

    A blast absorber test was conducted at the Aberdeen Test Centre from 13 to 17 June 2005. The test was set up to determine the absorbing and shielding effect of a gravel pile, of 1.5 meters high and 15 by 15 meters wide, on blasts from large weapons: e.g. armor, artillery or demolition. The blast was

  17. 14 CFR 29.475 - Tires and shock absorbers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 29.475 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must...

  18. 14 CFR 27.475 - Tires and shock absorbers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tires and shock absorbers. 27.475 Section... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.475 Tires and shock absorbers. Unless otherwise prescribed, for each specified landing condition, the tires must be assumed...

  19. Performance of Closely Spaced Point Absorbers with Constrained Floater Motion

    DEFF Research Database (Denmark)

    De Backer, G.; Vantorre, M.; Beels, C.;

    2009-01-01

    The performance of a wave energy converter array of twelve heaving point absorbers has been assessed numerically in a frequency domain model. Each point absorber is assumed to have its own linear power take-off. The impact of slamming, stroke and force restrictions on the power absorption...

  20. Photochromic And Thermochromic Pigments For Solar Absorbing-Reflecting Coatings

    Science.gov (United States)

    Novinson, Thomas

    1987-11-01

    Both photochromic and thermochromic compounds were synthesized and physical measurements were made to determine coefficients of relectance, absorbance and emission. The most interesting group of thermochromic compounds are related to silver tctraiodomercurate and the most interesting photochromic compounds are substituted benzoindolinopyrospirans. The synthesis and optical reflectance and absorbance properties of other classes of compounds are also reported.

  1. Primordial Radionuclides Distribution and dose Evaluation in Udagamandalam Region of Nilgiris in India

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, N. Muguntha; Selvasekarapandian, S.; Sivakumar, R.; Meenakshisundaram, V. [Bharathiar Univ., Coimbatore (India); Raghunath, V. M. [Indira Gandhi Center for Atomic Research, Kalpakkam (India)

    2001-09-15

    The activity concentration of primordial radionuclides i.e., {sup 238}U series, {sup 232}Th series and {sup 40}K, in soil samples collected from Udagamandalam environment, have been measured by employing NaI (TI) Gamma ray Spectrometer. The absorbed gamma dose rate has also been simultaneously measured by using both environmental radiation dosimeter at each soil sampling location (ambient gamma dose) as well as from the gamma dose derived from the activity concentration of the primordial radionuclides. The results of activity concentration of each radionuclides in soil, absorbed dose rate in air due to soil activity and possible cosmic radiation at each location along with human effective dose equivalent for Udagamandalam environment are presented and discussed.

  2. Why muscle is an efficient shock absorber.

    Directory of Open Access Journals (Sweden)

    Michael A Ferenczi

    Full Text Available Skeletal muscles power body movement by converting free energy of ATP hydrolysis into mechanical work. During the landing phase of running or jumping some activated skeletal muscles are subjected to stretch. Upon stretch they absorb body energy quickly and effectively thus protecting joints and bones from impact damage. This is achieved because during lengthening, skeletal muscle bears higher force and has higher instantaneous stiffness than during isometric contraction, and yet consumes very little ATP. We wish to understand how the actomyosin molecules change their structure and interaction to implement these physiologically useful mechanical and thermodynamical properties. We monitored changes in the low angle x-ray diffraction pattern of rabbit skeletal muscle fibers during ramp stretch compared to those during isometric contraction at physiological temperature using synchrotron radiation. The intensities of the off-meridional layer lines and fine interference structure of the meridional M3 myosin x-ray reflection were resolved. Mechanical and structural data show that upon stretch the fraction of actin-bound myosin heads is higher than during isometric contraction. On the other hand, the intensities of the actin layer lines are lower than during isometric contraction. Taken together, these results suggest that during stretch, a significant fraction of actin-bound heads is bound non-stereo-specifically, i.e. they are disordered azimuthally although stiff axially. As the strong or stereo-specific myosin binding to actin is necessary for actin activation of the myosin ATPase, this finding explains the low metabolic cost of energy absorption by muscle during the landing phase of locomotion.

  3. Graphene Based Terahertz Absorber Designed With Effective Surface Conductivity Approach

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

    Young field of terahertz (THz) science and technology demands new materials and devices, such as filters, modulators, polarization converters and absorbers. Graphene, a recently discovered single-atom-thick material, provides exciting properties for functional terahertz applications. Graphene...... conductivity and how to use it in optical design. We demonstrate a tunable THz perfect absorber, which consists of continuous graphene various structured graphene metamaterials above a metal mirror. Changing the Fermi level from 0 eV to 0.5 eV allows for drastic changes in absorbance from less than 0.1 to 1...... in the working range. We demonstrate the possibility of the absorber bandwidth control with the metamaterial’s unit cell geometry. The results of fabrication and characterization of the THz graphene metamaterials based absorbers will be presented at the conference....

  4. Structure and Performance Analysis of Regenerative Electromagnetic Shock Absorber

    Directory of Open Access Journals (Sweden)

    Longxin Zhen

    2010-12-01

    Full Text Available This paper analyzed the structure and principle of a regenerative electromagnetic shock absorber in detail. The innovative shock absorber resembles linear generator in principle and can generate electric power through the relative reciprocating motion between coil assembly and permanent magnet assembly. At the same time, the damping can remove discomfort caused by road roughness. The regenerated electric power can be recovered through battery. Analysis of magnetic flux density of the permanent magnet array of the innovative shock absorber was performed using ANSYS software based on the structure parameters given in the paper,then the performance parameters of the shock absorber was determined . Analysis and calculation results prove the viability of this shock absorber.

  5. Magnetically rotational reactor for absorbing benzene emissions by ionic liquids

    Institute of Scientific and Technical Information of China (English)

    Yangyang; Jiang; Chen; Guo; Huizhou; Liu

    2007-01-01

    A magnetically rotational reactor (MRR) has been developed and used in absorbing benzene emissions. The MRR has a permanent magnet core and uses magnetic ionic liquid [bmim]FeCl4 as absorbent. Benzene emissions were carried by N2 into the MRR and were absorbed by the magnetic ionic liquid. The rotation of the permanent magnet core provided impetus for the agitation of the magnetic ionic liquid, enhancing mass transfer and making benzene better dispersed in the absorbent. 0.68 g benzene emissions could be absorbed by a gram of [bmim]FeCl4, 0.27 and 0.40 g/ghigher than that by [bmim]PF6 and [bmim]BF4, respectively. The absorption rate increased with increasing rotation rate of the permanent magnet.

  6. Absorber-evaporator unit for an absorption-refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Hallatt, R.J.; Rorschach, R.L.

    1965-01-26

    This low temperature absorption-refrigeration system uses an absorber-evaporator. A conduit is connected between the upper portion of the absorber and the lower portion of the evaporator to conduct inert gas from the absorber to the evaporator. A second conduit connects the upper portion of the evaporator to the lower portion of the absorber and a blower in this conduit circulates the inert gas through the closed system. By placing the blower between the evaporator ad the absorber, the pressure in the evaporator is maintained at a minimum so that the working temperature is as low as possible. The medium to be cooled by the refrigerant is circulated through a heat exchanger located within the evaporator, whereby the latent heat of vaporization of the liquid refrigerant is employed to cool the outside medium. (2 claims)

  7. Performance evaluation of CFRP-rubber shock absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Lamanna, Giuseppe, E-mail: giuseppe.lamanna@unina2.it; Sepe, Raffaele, E-mail: giuseppe.lamanna@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, via Roma, 29 - 81031 Aversa (Italy)

    2014-05-15

    In the present work a numerical investigation on the energy absorbing capability of dedicated structural components made of a carbon fiber reinforced polymer and an emulsion polymerised styrene butadiene rubber is reported. The shock absorbers are devices designed to absorb large amounts of energy by sacrificing their own structural integrity. Their aim is to cushion the effects of an impact phenomenon with the intent to preserve other structures from global failure or local damaging. Another important role of shock absorbers is reducing the peak of the acceleration showed during an impact phenomenon. This effect is of considerable interest in the case of vehicles to preserve passengers’ safety. Static and dynamic numerical results are compared with experimental ones in terms of mean crushing forces, energy and peak crushing. The global performance of the absorbers has been evaluated by referencing to a proposed quality index.

  8. Tunable THz perfect absorber using graphene-based metamaterials

    Science.gov (United States)

    Faraji, Mahboobeh; Moravvej-Farshi, Mohammad Kazem; Yousefi, Leila

    2015-11-01

    A tunable THz absorber, with absorbance more than 90% is proposed, and numerically characterized. The absorber structure is based on metamaterials with unit cells consisting of two patterned graphene layers separated by a 5-nm thick layer of Al2O3. Numerical results show that when the chemical potential of the top graphene microribbons are tuned by an external variable bias and that of the lower graphene fishnet is kept at μC=0, frequency of the absorption peaks can be tuned as desired, therefore we can have a tunable or switchable absorber. The proposed absorber can have applications in designing tunable reflective THz filters or tunable THz switches and modulators. It can also be used for cloaking objects in THz range.

  9. Thermally Induced Nonlinear Optical Absorption in Metamaterial Perfect Absorbers

    CERN Document Server

    Guddala, Sriram; Ramakrishna, S Anantha

    2015-01-01

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks is fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.

  10. Dynamic Vibration Absorber with Negative Stiffness for Rotor System

    Directory of Open Access Journals (Sweden)

    Hongliang Yao

    2016-01-01

    Full Text Available To suppress the vibration of a rotor system, a vibration absorber combining negative stiffness with positive stiffness together is proposed in this paper. Firstly, the negative stiffness producing mechanism using ring type permanent magnets is presented and the characteristics of the negative stiffness are analyzed. Then, the structure of the absorber is proposed; the principles and nonlinear dynamic characteristics of the absorber-rotor system are studied numerically. Finally, experiments are carried out to verify the numerical conclusions. The results show that the proposed vibration absorber is effective to suppress the vibration of the rotor system, the nonlinearity of the negatives stiffness affects the vibration suppression effect little, and the negative stiffness can broaden the effective vibration control frequency range of the absorber.

  11. New Technology in Hydrogen Absorbers for Muon Cooling Channels

    CERN Document Server

    Cummings, M A C

    2005-01-01

    Ionization cooling is the only technique fast enough to cool and focus muons for neutrino factories and muon colliders, and hydrogen is the optimal material for maximum cooling and minimal multiple scattering. Liquid hydrogen absorber R&D for the Muon Collaboration has proceeded on parallel and complementary fronts. The continuing LH2 absorber engineering and technical developments by the MuCool group conducted by ICAR* institutions (NIU, IIT and UIUC), the University of Mississippi and Oxford University, in cooperation with Fermilab, will be summarized, including results from the first hydrogen absorber tests at the newly constructed FNAL Mucool Test Area (MTA). The program includes designs for the high-powered test of an absorber prototype (external heat exchange) at the MTA which are nearing completion to be installed by summer 2005, an alternative absorber design (internal heat exchange) being finalized for the approved cooling experiment (MICE) at Rutherford-Appleton Laboratory, and a novel idea for ...

  12. Multilayer metamaterial absorbers inspired by perfectly matched layers

    CERN Document Server

    Pastuszczak, Anna; Antosiewicz, Tomasz J; Kotynski, Rafal

    2014-01-01

    We derive periodic multilayer absorbers with effective uniaxial properties similar to perfectly matched layers (PML). This approximate representation of PML is based on the effective medium theory and we call it an effective medium PML (EM-PML). We compare the spatial reflection spectrum of the layered absorbers to that of a PML material and demonstrate that after neglecting gain and magnetic properties, the absorber remains functional. This opens a route to create electromagnetic absorbers for real and not only numerical applications and as an example we introduce a layered absorber for the wavelength of $8$~$\\mu$m made of SiO$_2$ and NaCl. We also show that similar cylindrical core-shell nanostructures derived from flat multilayers also exhibit very good absorptive and reflective properties despite the different geometry.

  13. Application of combined TLD and CR-39 PNTD method for measurement of total dose and dose equivalent on ISS

    Energy Technology Data Exchange (ETDEWEB)

    Benton, E.R. [Eril Research, Inc., Stillwater, Oklahoma (United States); Deme, S.; Apathy, I. [KFKI Atomic Energy Research Institute, Budapest (Hungary)

    2006-07-01

    To date, no single passive detector has been found that measures dose equivalent from ionizing radiation exposure in low-Earth orbit. We have developed the I.S.S. Passive Dosimetry System (P.D.S.), utilizing a combination of TLD in the form of the self-contained Pille TLD system and stacks of CR-39 plastic nuclear track detector (P.N.T.D.) oriented in three mutually orthogonal directions, to measure total dose and dose equivalent aboard the International Space Station (I.S.S.). The Pille TLD system, consisting on an on board reader and a large number of Ca{sub 2}SO{sub 4}:Dy TLD cells, is used to measure absorbed dose. The Pille TLD cells are read out and annealed by the I.S.S. crew on orbit, such that dose information for any time period or condition, e.g. for E.V.A. or following a solar particle event, is immediately available. Near-tissue equivalent CR-39 P.N.T.D. provides Let spectrum, dose, and dose equivalent from charged particles of LET{sub {infinity}}H{sub 2}O {>=} 10 keV/{mu}m, including the secondaries produced in interactions with high-energy neutrons. Dose information from CR-39 P.N.T.D. is used to correct the absorbed dose component {>=} 10 keV/{mu}m measured in TLD to obtain total dose. Dose equivalent from CR-39 P.N.T.D. is combined with the dose component <10 keV/{mu}m measured in TLD to obtain total dose equivalent. Dose rates ranging from 165 to 250 {mu}Gy/day and dose equivalent rates ranging from 340 to 450 {mu}Sv/day were measured aboard I.S.S. during the Expedition 2 mission in 2001. Results from the P.D.S. are consistent with those from other passive detectors tested as part of the ground-based I.C.C.H.I.B.A.N. intercomparison of space radiation dosimeters. (authors)

  14. Mathematical models and specific absorbed fractions of photon energy in the nonpregnant adult female and at the end of each trimester of pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Stabin, M.G.; Watson, E.E.; Cristy, M.; Ryman, J.C.; Eckerman, K.F. [Oak Ridge National Lab., TN (United States); Davis, J.L. [Tennessee Univ., Chattanooga, TN (United States); Marshall, D. [Florida Univ., Gainesville, FL (United States). Dept. of Nuclear Engineering; Gehlen, M.K. [San Diego State Univ., CA (United States)

    1995-05-08

    Mathematical phantoms representing the adult female at three, six, and nine months of gestation are described. They are modifications of the 15-year-old male/adult female phantom (15-AF phantom) of Cristy and Eckerman (1987). The model of uterine contents includes the fetus, fetal skeleton, and placenta. The model is suitable for dose calculations for the fetus as a whole; individual organs within the fetus (other than the skeleton) are not modeled. A new model for the nonpregnant adult female is also described, comprising (1) the 15-AF phantom; (2) an adjustment to specific absorbed fractions for organ self-dose from photons to better match Reference Woman masses; and (3) computation of specific absorbed fractions with Reference Woman masses from ICRP Publication 23 for both penetrating and nonpenetrating radiations. Specific absorbed fractions for photons emitted from various source regions are tabulated for the new non;pregnant adult female model and the three pregnancy models.

  15. Comparison of Dose When Prescribed to Point A and Point H for Brachytherapy in Cervical Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Gang, Ji Hyeong; Gim, Il Hwan; Hwang, Seon Boong; Kim, Woong; Im, Hyeong Seo; Gang, Jin Mook; Gim, Gi Hwan; Lee, Ah Ram [Dept. of Radiation Oncology, Korea Institute of Radiological and Medical Sciences, Seou (Korea, Republic of)

    2012-09-15

    The purpose of this study is to compare plans prescribed to point A with these prescribed to point H recommended by ABS (American Brachytherapy Society) in high dose rate intracavitary brachytherapy for cervical carcinoma. This study selected 103 patients who received HDR (High Dose Rate) brachytherapy using tandem and ovoids from March 2010 to January 2012. Point A, bladder point, and rectal point conform with Manchester System. Point H conforms with ABS recommendation. Also Sigmoid colon point, and vagina point were established arbitrarily. We examined distance between point A and point H. The percent dose at point A was calculated when 100% dose was prescribed to point H. Additionally, the percent dose at each reference points when dose is prescribed to point H and point A were calculated. The relative dose at point A was lower when point H was located inferior to point A. The relative doses at bladder, rectal, sigmoid colon, and vagina points were higher when point H was located superior to point A, and lower when point H was located inferior to point A. This study found out that as point H got located much superior to point A, the absorbed dose of surrounding normal organs became higher, and as point H got located much inferior to point A, the absorbed dose of surrounding normal organs became lower. This differences dose not seem to affect the treatment. However, we suggest this new point is worth being considered for the treatment of HDR if dose distribution and absorbed dose at normal organs have large differences between prescribed to point A and H.

  16. Improvement on the wave absorbing property of a lossy frequency selective surface absorber using a magnetic substrate

    Institute of Scientific and Technical Information of China (English)

    Sun Liang-Kui; Cheng Hai-Feng; Zhou Yong-Jiang; Wang Jun

    2012-01-01

    An equivalent-circuit model is used to analyse the improvement of the wave absorbing performance of the lossy frequency selective surface(FSS)absorber by using a magnetic substrate,showing that it is possible to widen the wave absorbing bandwidth.Three pieces of magnetic substrates are prepared.According to the complex permittivity and permeability,the reflectivity of the corresponding absorber is calculated by the finite difference time-domain(FDTD)method,and the bandwidth of the reflectivity below-10 dB is optimized by genetic algorithm.The calculated results indicate that the wave absorbing performance is significantly improved by increasing the complex permeability of the substrate; the reflectivity bandwidth below-10 dB of the single layer FSS absorber can reach 3.6-18 GHz with a thickness of 5 mm,which is wider than that with a dielectric substrate.The density of the FSS absorber is only 0.92 g/cm3.Additionally,the absorption band can be further widened by inserting a second lossy FSS.Finally,a double layer lossy FSS absorber with a magnetic substrate is fabricated based on the design result.The experimental result is consistent with the design one.

  17. Imaging and Measuring Electron Beam Dose Distributions Using Holographic Interferometry

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    Holographic interferometry was used to image and measure ionizing radiation depth-dose and isodose distributions in transparent liquids. Both broad and narrowly collimated electron beams from accelerators (2–10 MeV) provided short irradiation times of 30 ns to 0.6 s. Holographic images and measur......Holographic interferometry was used to image and measure ionizing radiation depth-dose and isodose distributions in transparent liquids. Both broad and narrowly collimated electron beams from accelerators (2–10 MeV) provided short irradiation times of 30 ns to 0.6 s. Holographic images...... and measurements of absorbed dose distributions were achieved in liquids of various densities and thermal properties and in water layers thinner than the electron range and with backings of materials of various densities and atomic numbers. The lowest detectable dose in some liquids was of the order of a few k...

  18. Microwave absorbance properties of zirconium–manganese substituted cobalt nanoferrite as electromagnetic (EM) wave absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Kishwar, E-mail: kknano@hotmail.com; Rehman, Sarish

    2014-02-01

    Highlights: • Good candidates for EM materials with low reflectivity. • Good candidates for broad bandwidth at microwave frequency. • Microwave absorbing bandwidth was modulated simply by manipulating the Zr–Mn. • Higher the Zr–Mn content, the higher absorption rates for the electromagnetic radiation. • The predicted reflection loss shows that this can be used for thin ferrite absorber. - Abstract: Nanocrystalline Zr–Mn (x) substituted Co ferrite having chemical formula CoFe{sub 2−2x}Zr{sub x}Mn{sub x}O{sub 4} (x = 0.1–0.4) was prepared by co-precipitation technique. Combining properties such as structural, electrical, magnetic and reflection loss characteristics. Crystal structure and surface morphology of the calcined samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). By using two point probe homemade resistivity apparatus to find resistivity of the sample. Electromagnetic (EM) properties are measured through RF impedance/materials analyzer over 1 MHz–3 GHz. The room-temperature dielectric measurements show dispersion behavior with increasing frequency from 100 Hz to 3 MHz. Magnetic properties confirmed relatively strong dependence of saturation magnetization on Zr–Mn composition. Curie temperature is also found to decrease linearly with addition of Zr–Mn. Furthermore, comprehensive analysis of microwave reflection loss (RL) is carried out as a function of substitution, frequency, and thickness. Composition accompanying maximum microwave absorption is suggested.

  19. AAPM/RSNA Physics Tutorial for Residents: Topics in CT. Radiation dose in CT.

    Science.gov (United States)

    McNitt-Gray, Michael F

    2002-01-01

    This article describes basic radiation dose concepts as well as those specifically developed to describe the radiation dose from computed tomography (CT). Basic concepts of radiation dose are reviewed, including exposure, absorbed dose, and effective dose. Radiation dose from CT demonstrates variations within the scan plane and along the z axis because of its unique geometry and usage. Several CT-specific dose descriptors have been developed: the Multiple Scan Average Dose descriptor, the Computed Tomography Dose Index (CTDI) and its variations (CTDI(100), CTDI(w), CTDI(vol)), and the dose-length product. Factors that affect radiation dose from CT include the beam energy, tube current-time product, pitch, collimation, patient size, and dose reduction options. Methods of reducing the radiation dose to a patient from CT include reducing the milliampere-seconds value, increasing the pitch, varying the milliampere-seconds value according to patient size, and reducing the beam energy. The effective dose from CT can be estimated by using Monte Carlo methods to simulate CT of a mathematical patient model, by estimating the energy imparted to the body region being scanned, or by using conversion factors for general anatomic regions. Issues related to radiation dose from CT are being addressed by the Society for Pediatric Radiology, the American Association of Physicists in Medicine, the American College of Radiology, and the Center for Devices and Radiological Health of the Food and Drug Administration.

  20. Ultrathin planar broadband absorber through effective medium design

    Institute of Scientific and Technical Information of China (English)

    Dong Liu; Haitong Yu; Zhen Yang; Yuanyuan Duan

    2016-01-01

    Ultrathin planar absorbers hold promise in solar energy systems because they can reduce the material,fabrication,and system cost.Here,we present a general strategy of effective medium design to realize ultrathin planar broadband absorbers.The absorber consists of two ultrathin absorbing dielectrics to designan effective absorbing medium,a transparent layer,and metallic substrate.Compared with previous studies,this strategy provides another dimension of freedom to enhance optical absorption;therefore,destructive interference can be realized over a broad spectrum.To demonstrate the power and simplicity of this strategy,we both experimentally and theoretically characterized an absorber with 5-nm-thick Ge,10-nm-thick Ti,and 50-nm-thick SiO2 films coated on an Ag substrate fabricated using simple deposition methods.Absorptivity higher than 80% was achieved in 15-nm-thick (1/50 of the center wavelength) Ge and Ti films from 400 nm to near 1 μm.As an application example,we experimentally demonstrated that the absorber exhibited a normal solar absorptivity of 0.8 with a normal emittance of 0.1 at 500 ℃,thus demonstrating its potential in solar thermal systems.The effective medium design strategy is general and allows material versatility,suggesting possible applications in real-time optical manipulation using dynamic materials.