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Sample records for absorbed dose determination

  1. Determination of absorbed dose in reactors

    International Nuclear Information System (INIS)

    There are many areas in the use and operation of research reactors where the absorbed dose and the neutron fluence are required. These include work on the determination of the radiolytic stability of the coolant and moderator and on the determination of radiation damage in structural materials, and reactor experiments involving radiation chemistry and radiation biology. The requirements range from rough estimates of the total heating due to radiation to precise values specifying the contributions of gamma rays, thermal neutrons and fast neutrons. To meet all these requirements a variety of experimental measurements and calculations as well as a knowledge of reactor radiations and their interactions is necessary. Realizing the complexity and importance of this field, its development at widely separated laboratories and the need to bring the experts in this work together, the IAEA has convened three panel meetings. These were: 'In-pile dosimetry', held in July 1964 (published by the Agency as Technical Reports Series No. 46); 'Neutron fluence measurements', in October 1965; and 'In-pile dosimetry', in November 1966. The recommendations of these three panels led the Agency to form a Working Group on Reactor Radiation Measurements and to commission the writing of this book and a book on Neutron Fluence Measurements. The latter was published in May 1970 (Technical Reports Series No. 107). The material on neutron fluence and absorbed dose measurements is widely scattered in reports and reviews. It was considered that it was time for all relevant information to be evaluated and put together in the form of a practical guide that would be valuable both to experienced workers and beginners in the field

  2. Neutron absorbed dose determination by calculations of recoil energy.

    Science.gov (United States)

    Wrobel, F; Benabdesselam, M; Iacconi, P; Lapraz, D

    2004-01-01

    The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy. PMID:15353750

  3. Determination of neutron absorbed doses in lithium aluminates.

    Science.gov (United States)

    Delfín Loya, A; Carrera, L M; Ureña-Núñez, F; Palacios, O; Bosch, P

    2003-04-01

    Lithium-based ceramics have been proposed as tritium breeders for fusion reactors. The lithium aluminate (gamma phase) seems to be thermally and structurally stable, the damages produced by neutron irradiation depend on the absorbed dose. A method based on the measurement of neutron activation of foils through neutron capture has been developed to obtain the neutron absorbed dose in lithium aluminates irradiated in the thermal column facility and in the fixed irradiation system of a Triga Mark III Nuclear Reactor. PMID:12672632

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

    International Nuclear Information System (INIS)

    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, CaF2: Dy thermoluminescent dosemeters and a Harshaw 3500 reading system are employed. Dosemeters are characterized with 90Sr-90Y, calibrated with the energy of 60Co 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 5%. The reason of the answers of the CaF2: Dy and LiF: Mg, Ti, according to the energy of the radiation, allows us to establish the effective energy of photons and the absorbed dose, with a margin of error of less than 10% and 20% respectively

  5. 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 ...

  6. 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.

  7. Radiation absorbed dose estimate for rubidium-82 determined from in vivo measurements in human subjects

    International Nuclear Information System (INIS)

    Radiation absorbed doses from rubidium-82 injected intravenously were determined in two young men, aged 23 and 27, using a dynamic conjugate counting technique to provide data for the net organ integrated time-activity curves in five organs: kidneys, lungs, liver, heart, and testes. This technique utilized a tungsten collimated Anger camera and the accuracy was validated in a prestwood phantom. The data for each organ were compared with conjugate count rates of a reference Ge-68/Ga-68 standard which had been calibrated against the Rb-82 injected. The effects of attenuation in the body were eliminated. The MIRD method was used to calculate the organ self absorbed doses and the total organ absorbed doses. The mean total absorbed doses were as follows (mrads/mCi injected): kidneys 30.9, heart walls 7.5, lungs 6.0, liver 3.0, testes 2.0 (one subject only), red marrow 1.3, remainder of body 1.3 and, extrapolating to women, ovaries 1.2. This absorbed dose to the kidney is significantly less than the pessimistic estimate of 59.4 mrads/mCi, made assuming instantaneous uptake and complete extraction of activity with no excretion by the kidneys, which receive 20% of the cardiac output. Further, in a 68 year old man the renal self absorbed dose was approximately 40% less than the mean renal self absorbed dose of the younger men. This decrease is probably related to the decline in renal blood flow which occurs with advancing age but other factors may also contribute to the observed difference. 14 references, 4 figures, 2 tables

  8. Regression models in the determination of the absorbed dose with extrapolation chamber for ophthalmological applicators

    International Nuclear Information System (INIS)

    The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, (90 Sr/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)

  9. Code of practice for absorbed dose determination in photon and electron beams

    International Nuclear Information System (INIS)

    An advisory group was set up by the IAEA to suggest measures to be taken for the production of a dosimetry protocol. The authors of the paper were chosen to be authors. The Agency was of the opinion that such a protocol would be of great value not only to the network of Secondary Standard Dosimetry Laboratories (SSDL) but also to hospitals providing radiation treatment for cancer patients. The report includes recommendations on the procedure for determining the absorbed dose at low and medium energy X-rays, and high energy photon and electron radiation. Advice on equipment, measurement geometry and quality assurance is given. It was decided that the symbols and formalism should follow the ICRU recommendations. The numerical data on interaction coefficients follow the recommendations of the standards laboratories (i.e. CCEMRI). Correction factors (i.e. katt and km) to be applied for about 40 types of commercial ionization chambers were computed as it was considered that it would be difficult to restrict the use to a few types of chambers, as in the NACP protocol, or advise the users on how to carry out complicated computations, as in the AAPM protocol. A part of the report is devoted to conventional X-rays. In this case a very general type of formalism is suggested. It was found that there is a lack of information on the correction factors to be applied for different types of chambers. Furthermore, it was found that conventional dosimetry procedures, often used in determining the absorbed dose at the medium energy range of X-rays, underestimate the absorbed dose by several per cent. More work is needed in this field. An independent evaluation of the dosimetry resulting from the application of this protocol has been carried out for high energy photon and electron radiation using the FeSO4 dosimeter as a reference. The agreement in absorbed dose values was generally within fractions of one per cent. The conclusion is, therefore, that use of this report can give an

  10. Genetic effects induced by neutrons in Drosophila melanogaster I. Determination of absorbed dose.

    Science.gov (United States)

    Delfin, A; Paredes, L C; Zambrano, F; Guzmán-Rincón, J; Ureña-Nuñez, F

    2001-12-01

    A method to obtain the absorbed dose in Drosophila melanogaster irradiated in the thermal column facility of the Triga Mark III Reactor has been developed. The method is based on the measurements of neutron activation of gold foils produced by neutron capture to obtain the neutron fluxes. These fluxes, combined with the calculations of kinetic energy released per unit mass, enables one to obtain the absorbed doses in Drosophila melanogaster. PMID:11761104

  11. Influence analysis of the variations on quality control parameters in determination of absorbed dose in water

    International Nuclear Information System (INIS)

    The reference condition established to determine the absorbed dose in water of a linear accelerator, according to TRS-398, depends on some electro-mechanics parameters. Furthermore, in principle, uncertainties in the parameters settings may results in dosimetry variations. The goal of this study is to analyze the influence in quality control parameters changes, which tolerance limits are established by TECDOC-1151, in the dosimetry result of photon beam. For this, some parameters (gantry and collimator angle, field size and source to surface distance) and chamber position were changed. The results of these changes were evaluated. For the variation range of quality control items (that went beyond the tolerance limits established by TECDOC-1151), the deviations got less than 1 % of reference for all analyzed parameters; the deviations for the ionization chamber position variation were less than 0,2 % for lateral and longitudinal variations although almost got to 3 % for depth alterations. (author)

  12. Influence analysis of the variations on quality control parameters in determination of absorbed dose in water

    International Nuclear Information System (INIS)

    The reference condition established to determine the absorbed dose in water of a linear accelerator, according to Tars-398, depends on some electro-mechanics parameters. Furthermore, in principle, uncertainties in the parameters settings may results in dosimetry variations. The goal of this study is to analyze the influence in quality control parameters changes, which tolerance limits are established by TECDOC-1151, in the dosimetry result of photon beam. For this, some parameters (gantry and collimator angle, field size and source to surface distance) and chamber position were changed. The results of these changes were evaluated. For the variation range of quality control items (that went beyond the tolerance limits established by TECDOC-1151), the deviations got less than 1 % of reference for all analyzed parameters; the deviations for the ionization chamber position variation were less than 0,2 % for lateral and longitudinal variations although almost got to 3% for depth alterations. (author)

  13. Validation of a MOSFET dosemeter system for determining the absorbed and effective radiation doses in diagnostic radiology.

    Science.gov (United States)

    Manninen, A-L; Kotiaho, A; Nikkinen, J; Nieminen, M T

    2015-04-01

    This study aimed to validate a MOSFET dosemeter system for determining absorbed and effective doses (EDs) in the dose and energy range used in diagnostic radiology. Energy dependence, dose linearity and repeatability of the dosemeter were examined. The absorbed doses (ADs) were compared at anterior-posterior projection and the EDs were determined at posterior-anterior, anterior-posterior and lateral projections of thoracic imaging using an anthropomorphic phantom. The radiation exposures were made using digital radiography systems. This study revealed that the MOSFET system with high sensitivity bias supply set-up is sufficiently accurate for AD and ED determination. The dosemeter is recommended to be calibrated for energies 80 kVp. The entrance skin dose level should be at least 5 mGy to minimise the deviation of the individual dosemeter dose. For ED determination, dosemeters should be implanted perpendicular to the surface of the phantom to prevent the angular dependence error. PMID:25213263

  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. Determination of human absorbed dose of cocktail of 153Sm/177Lu-EDTMP, based on biodistribution data in rats

    International Nuclear Information System (INIS)

    The aim of this work was to estimate the absorbed dose due to compositional radiopharmaceutical of 153Sm/177Lu-EDTMP in human organs based on biodistribution data of rats by using OLINDA/EXM software. The absorbed dose was determined by the Radiation Dose Assessment Resource (RADAR) formulation after calculating cumulated activities in each organ. The results show that the organs that received the highest absorbed dose were the bone surface and red marrow (1.51 and 7.99 mGy/ MBq for 153Sm, and 1.98 and 10.76 mGy/MBq for 177Lu, respectively). According to the results, using of cocktail of 153Sm/177Lu-EDTMP has considerable characteristics as compared to 153Sm-EDTMP and 177Lu-EDTMP alone. (author)

  16. Research on the determination of 235U fission number by delayed γ-rays absorbed dose rates

    International Nuclear Information System (INIS)

    Background: The determination method of 235U fission number by detecting fission products using HPGe detector has been established before. But in some special cases, we need to get the fission number in-time in high intensity radiation environment. HPGe detector has its limitation due to the complex y spectrum accompany with high flux. Purpose: To get rid of the limitation mentioned above, a new method is introduced by detecting the delayed γ-rays absorbed dose rates. Methods: By using independent fission yield together with radioactive decay dates from CENDL 3.0 and ENDF BVII.1, dynamic calculation for total absorbed dose rate in air 1 meter from the source whose compositions were thermal neutron-induced fission products of 235U has been done. Results: A set of absorbed dose rate data of 235U fission products irradiated through fast rabbit irradiation system on Xi'an pulse reactor was recorded. The deviation of the fission neutron number between method by γ-rays absorbed dose rates and method by HPGe detector is 7%. Conclusion: It's feasible to determine the fission neutron number of 235U using delayed γ-rays absorbed dose rates in a high intensity radiated environment. (authors)

  17. 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.

  18. Identification and absorbed dose determination in irradiated kiwi by electron paramagnetic resonance; Identificacao e medida de dose absorvida em kiwi irradiado utilizando ressonancia paramagnetica eletronica

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Edgar F.O. de; Lopes, Ricardo T. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Rossi, Alexandre M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    1997-12-01

    A methodology for identification and absorbed dose determination in irradiated Kiwi with doses between 200 and 1000 Gy is present. Measurement are performed by Electron Paramagetic Resonance (ESR) in the flesh of the fruit after alcohol extration that removes water and soluble substances. The signal used is the radial produced in cellulose by radiation that shows to be stable during the usefull life of the fruit and that is not present in non-irradiated samples. Reference samples are not necessary to dose determination and the results shows that 85% of the calculated values are found to be within {+-} 15% of the applied initial dose. (author). 9 refs., 5 figs., 2 tabs.

  19. Ionization current measurements using and extrapolation chamber for the determination of the absorbed dose from β emitters

    International Nuclear Information System (INIS)

    In order to obtain the beta response of survey instruments, the working group no.5 of the C.E.A. Radiation Offices has studied an extrapolation chamber as reference apparatus. The value of the different correcting factors which modify the number of ions pairs collected per mass of air, in other words, the absorbed dose in the air of the cavity is reported. Then, the physical constants (transmission, back-scattering...) which are necessary to pass from the absorbed dose in the air of the cavity, to the absorbed dose in the tissue for a semi-infinite medium below a thickness of 7.5mg/cm2 are given. The absorbed dose in tissue, to within an error of about 4%, can be estimated

  20. 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...

  1. Determination of an Absorbed Dose of MOSFET Dosimeter using Monte Carlo N-Particle Simulation with Different Tallies and Response Functions

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Hae Ri; Hong, Ser Gi [Kyung Hee University, Yongin (Korea, Republic of); Kim, Yong Nam; Kim, Soo Kon [Kangwon National University Hospital, Chuncheon (Korea, Republic of)

    2015-05-15

    In this paper, we performed MOSFET dosimeter simulation using the latest MCNP version code (MCNP 6). In order to determine the absorbed dose, we set the four source positions of 0 .deg. , 90 .deg. , 180 .deg. and 270 .deg. directions as in the previous study2. And, the absorbed dose traversed by electrons in the sensitive volume of extremely thin layer (1..m) was determined by both F4 tally (i.e., track length estimator) and F8 tally (i.e., energy deposition tally). However, the accurate determination of the absorbed dose in the very small volume is quite difficult due to the extremely small sensitive volume, which results a large variance in the tally with the typical number of source particles. To resolve this difficulty, we used MCNP [ESTEP] option and F4 tally. In this paper, we performed Monte Carlo simulation of MOSFET dosimeter using MCNP6. In particular, the F4 track length and*F8 energy deposition estimators coupled with the ESTEP option in MCNP [Material data card] were used to accurately estimate the absorbed doses in the extremely small sensitive volume. In order to calculate the absorbed dose in the sensitive volume, we used MCNP F4 tally which is referred to the track length estimator and F8 tally. The ESTEP option in MCNP accommodates enough number of sub-steps for an accurate simulation of the electron's trajectory. Also, MCNP [DE card] and [DF card] are used in the track length estimator to determine the absorbed dose over the sensitive volume. Also, we considered two different response functions in the F4 track length tally to calculate the absorbed doses. The first one is calculated with the formulations suggested by Schaart et al and the second one is the mass electronic collision stopping power which was extracted from MCNP output.

  2. 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...

  3. Correction factors for Farmer-type chambers for absorbed dose determination in 60Co and 192Ir brachytherapy dosimetry

    International Nuclear Information System (INIS)

    This paper presents experimentally determined correction factors for Farmer-type chambers for absorbed dose determination in 60Co and 192Ir brachytherapy dosimetry. The correction factors were determined from measurements made in a PMMA phantom and calculation of ratios of measured charges. The ratios were corrected for the different volumes of the ionization chambers, determined in external high-energy electron beams. The correction factors for the central electrode effect and the wall material dependency in 60Co brachytherapy dosimetry agree with those used in external 60Co beam dosimetry. In 192Ir dosimetry, the central aluminium electrode increases the response of an NE2571 chamber compared with that of a chamber with a central graphite electrode. The increase is 1.1 and 2.1% at 1.5 and 5.0 g cm-2 distance, respectively. Similar values are obtained with an NE2577 chamber. The wall correction factor in 192Ir dosimetry for a chamber with an A-150 wall has been determined to be 1.018, independent of the measurement distance. For a graphite walled chamber, the correction factor is 0.996 and 1.001 at 1.5 and 5.0 g cm-2 distance, respectively. The values of the wall correction factors are evaluated by a theory presented. If the chamber is used according to the 'large cavity' principle, the correction factor to account for the replacement of the phantom material by the ionization chamber was determined to be 0.982 for an NE2571 chamber when used with a Delrin cap, and 0.978 for an NE2581 when used with a polystyrene cap. The correction factors for the 'large cavity' principle are valid at both 60Co and 192Ir qualities. (author)

  4. Determination of absorbed dose of ozone (O3) in animals and humans using stable-isotope (oxygen-18) tracing

    Energy Technology Data Exchange (ETDEWEB)

    Hatch, G.E.; Aissa, M.

    1987-05-01

    A method for the determination of absorbed dose of ozone (O3) in animals and humans using oxygen-18 YO as a physiological tracer is presented. The experimental aspects of the method are based on the instantaneous pyrolysis of tissue samples and subsequent conversion of the sample oxygen to carbon monoxide then to carbon dioxide whose isotopic composition is determined by isotope-ratio mass spectrometry. A mathematical procedure is then used to correct the isotopic data for interferences from the blank and memory effects and from the iodine pentoxide oxidation of CO to CO2. Laboratory animals were exposed to YO3 (1 ppm, 1 hr) then tissues were dried and processed for YO measurement. Enrichments in YO over natural abundance YO was observed in lung homogenates, nasal cavities, trachea, and pulmonary lavage fluids but not in blood of mice, rats, and rabbits. Thus, the YO tracing method appears to be sensitive enough to detect the reaction products of YO in animals exposed to near environmental concentrations of this gas.

  5. 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

  6. The MIRD method of estimating absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Weber, D.A.

    1991-01-01

    The estimate of absorbed radiation dose from internal emitters provides the information required to assess the radiation risk associated with the administration of radiopharmaceuticals for medical applications. The MIRD (Medical Internal Radiation Dose) system of dose calculation provides a systematic approach to combining the biologic distribution data and clearance data of radiopharmaceuticals and the physical properties of radionuclides to obtain dose estimates. This tutorial presents a review of the MIRD schema, the derivation of the equations used to calculate absorbed dose, and shows how the MIRD schema can be applied to estimate dose from radiopharmaceuticals used in nuclear medicine.

  7. On the definition of absorbed dose

    International Nuclear Information System (INIS)

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before. - Highlights: • A stringent definition of absorbed dose is given. • This requires the definition of an irradiation and a suitable probability space. • A stringent definition is important for an understanding of the concept absorbed dose

  8. 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)

  9. On the definition of absorbed dose

    Science.gov (United States)

    Grusell, Erik

    2015-02-01

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before.

  10. Experimental and theoretical determination of absorbed microwave dose rate distributions in phantom heads irradiated by an aperture source

    International Nuclear Information System (INIS)

    A thermographic technique is used to determine absorbed microwave energy distribution in phantom monkey and human heads irradiated by an aperture source. The phantom heads are brain equivalent tissue spheres and a bone and brain tissue geometric model of a monkey head. The results of the experiment are compared to patterns obtained from theoretical calculations, indicating good general agreement between experimental and theoretical data. The penetration of microwave energy is less for the phantom human head than for the monkey head. The overall poor penetration of the radiation due to the 2450 MHz aperture source used in this experiment indicates a need for further research using frequency and aperture dimensions as parameters to obtain desired microwave absorption patterns for both biological experiments and therapeutic applications. (author)

  11. 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)

  12. Determination of Absorbed Dose to Water in Megavoltage Electron Beams Using a Calorimeter-Fricke Hybrid System

    International Nuclear Information System (INIS)

    A water calorimeter-Fricke solution hybrid dosimetry system was developed at the National Research Council of Canada to be used for reference dosimetry for high energy electron beams in the energy range produced by medical linear accelerators. The system uses water calorimetry for higher energy beams of 18 MeV and 22 MeV, while Fricke dosimetry is used for the lower energies of 4 MeV, 8 MeV and 12 MeV. Fricke solution dosimetry was also used for 18 MeV and 22 MeV to determine the Fricke solution's ε·G(Fe3+) coefficient needed for calculations at lower energies. The deviation from linearity of the system in the dose range from 6 to 52 Gy was typically 0.2-0.3% for all energies, while the average repeatability for a single dosimeter was about 1%. As a practical application, the energy dependence of the response of a parallel-plate ionization chamber was investigated. It was found that at higher energies, the predictions were similar to those calculated by TG-51 and TRS 398, while for lower energies, differences were observed of up to 1%, consistent with new Monte Carlo and experimental investigations of chamber perturbation corrections,. (author)

  13. Patient absorbed radiation doses estimation related to irradiation anatomy

    International Nuclear Information System (INIS)

    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

  14. Determination of absorbed dose of ozone (03) in animals and humans using stable isotope (oxygen-18) tracing

    Energy Technology Data Exchange (ETDEWEB)

    Hatch, G.E. (U.S. Environmental Protection Agency, Research Triangle Park, NC (US)); Aissa, M. (Northrop Services, Inc., Research Triangle Park, NC (USA))

    1987-01-01

    Ozone (O{sub 3}) is one of the most common photochemical oxidants and it also appears to be the most toxic. Its toxicity most likely arises from either direct reaction with tissue constituents or initiation of free radical-induced autoxidation. The toxicology data base on O{sub 3} is extensive, particularly with regard to animal inhalation studies. There is a need to relate the animal toxicology data to human exposure conditions in order to provide more accurate risk assessments. Estimates for the dose of O{sub 3} to specific sites along the respiratory tract following inhalation have been attempted based on mathematical models which account for both transport and absorption of oxidants in respiratory airways. These models agreed with experimental results in that the most likely sites of damage were the respiratory bronchioles and alveolar ducts, but quantitative verification of the predicted dose has not been possible. Previous studies funded by the EPA made a significant contribution to this problem by tracing O{sub 3} using the stable isotope, {sup 18}O. Preliminary work on the implementation and improvement of this technique is presented.

  15. 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)

  16. 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.

  17. Problems in radiation absorbed dose estimation from positron emitters

    International Nuclear Information System (INIS)

    The positron emitters commonly used in clinical imaging studies for the most part are short-lived, so that when they are distributed in the body the radiation absorbed dose is low even though most of the energy absorbed is from the positrons themselves rather than the annihilation radiation. These considerations do not apply to the administration pathway for a radiopharmaceutical where the activity may be highly concentrated for a brief period rather than distributed in the body. Thus, high local radiation absorbed doses to the vein for an intravenous administration and to the upper airways during administration by inhalation can be expected. For these geometries, beta point source functions (FPS's) have been employed to estimate the radiation absorbed dose in the present study. Physiologic measurements were done to determine other exposure parameters for intravenous administration of O-15 and Rb-82 and for administration of O-15-CO2 by continuous breathing. Using FPS's to calculate dose rates to the vein wall from O-15 and Rb-82 injected into a vein having an internal radius of 1.5 mm yielded dose rates of 0.51 and 0.46 (rad x g/μCi x h), respectively. The dose gradient in the vein wall and surrounding tissues was also determined using FPS's. Administration of O-15-CO2 by continuous breathing was also investigated. Using ultra-thin thermoluninescent dosimeters (TLD's) having the effective thickness of normal tracheal mucosa, experiments were performed in which 6 dosimeters were exposed to known concentrations of O-15 positrons in a hemicylindrical tracheal phantom having an internal radius of 0.96 cm and an effective length of 14 cm. The dose rate for these conditions was 3.4 (rads/h)/(μCi/cm3). 15 references, 7 figures, 6 tables

  18. Determination of the optimal statistical uncertainty to perform electron-beam Monte Carlo absorbed dose estimation in the target volume; Determination de l'incertitude statistique optimale pour realiser un calcul de dose dans le volume cible en utilisant la methode de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Isambert, A.; Lefkopoulos, D. [Institut Gustave-Roussy, Medical Physics Dept., 94 - Villejuif (France); Brualla, L. [NCTeam, Strahlenklinik, Universitatsklinikum Essen (Germany); Benkebil, M. [DOSIsoft, 94 - Cachan (France)

    2010-04-15

    Purpose of study Monte Carlo based treatment planning system are known to be more accurate than analytical methods for performing absorbed dose estimation, particularly in and near heterogeneities. However, the required computation time can still be an issue. The present study focused on the determination of the optimum statistical uncertainty in order to minimise computation time while keeping the reliability of the absorbed dose estimation in treatments planned with electron-beams. Materials and methods Three radiotherapy plans (medulloblastoma, breast and gynaecological) were used to investigate the influence of the statistical uncertainty of the absorbed dose on the target volume dose-volume histograms (spinal cord, intra-mammary nodes and pelvic lymph nodes, respectively). Results The study of the dose-volume histograms showed that for statistical uncertainty levels (1 S.D.) above 2 to 3%, the standard deviation of the mean dose in the target volume calculated from the dose-volume histograms increases by at least 6%, reflecting the gradual flattening of the dose-volume histograms. Conclusions This work suggests that, in clinical context, Monte Carlo based absorbed dose estimations should be performed with a maximum statistical uncertainty of 2 to 3%. (authors)

  19. 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.

  20. Specification of absorbed dose for reporting a therapeutic irradiation

    International Nuclear Information System (INIS)

    The problem of dose specification in external beam therapy with photons and electrons has been dealt with in ICRU Report 29 (1978). This problem arises from the fact that the absorbed dose distribution is usually not uniform in the target volume and that for the purpose of treatment reporting a nominal absorbed dose - which will be called target absorbed dose - has to be selected. When comparing the clinical results obtained between radiotherapy centres, the differences in the reported target absorbed doses which can be introduced by differences in the methods of dose specification often are much larger than the differences related to the dosimetric procedures themselves. This shows the importance of the problem. In this paper, some definitions of terms and concepts currently used in radiotherapy are first recalled: tumour volume, target volume, treatment volume, etc. These definitions have been proposed in ICRU Report 29 for photon and electron beams; they can be extended to any kind of irradiation. For external beam therapy with photons and electrons, the target absorbed dose is defined as the absorbed dose at selected point(s) (specification point(s)) having a meaningful relation to the target volume and/or the irradiation beams. Examples are discussed for typical cases. As far as interstitial and intracavitary therapy is concerned, the problem is more complex and no recommendations have so far been made by the ICRU Commission. A major difficulty arises from the sharp dose gradient as a function of the distance to the sources. The particular case of the treatment of cervix carcinoma is considered and some possible methods of specification are discussed: (1) the indication of the sources (in adequate units) and the duration of the application, (2) the absorbed doses at selected reference points (bladder, rectum, bony structures) and (3) the description of the tissue volume (height, width, thickness) encompassed by a given isodose surface (60Gy). (author)

  1. 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)

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

    Science.gov (United States)

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

    2013-06-01

    The ARPANSA calibration service for (60)Co gamma rays is based on a primary standard graphite calorimeter that measures absorbed dose to graphite. Measurements with the calorimeter are converted to the absorbed dose to water using the calculation of the ratio of the absorbed dose in the calorimeter to the absorbed dose in a water phantom. ARPANSA has recently changed the basis of this calculation from a photon fluence scaling method to a direct Monte Carlo (MC) calculation. The MC conversion uses an EGSnrc model of the cobalt source that has been validated against water tank and graphite phantom measurements, a step that is required to quantify uncertainties in the underlying interaction coefficients in the MC code. A comparison with the Bureau International des Poids et Mesures (BIPM) as part of the key comparison BIPM.RI(I)-K4 showed an agreement of 0.9973 (53). PMID:23152147

  3. Phantoms for calculations of absorbed organ dose

    International Nuclear Information System (INIS)

    We have developed a computer code IDES (Internal Dose Estimation System). In this code, MIRD Transformation Method is used and photon simulation by Monte Carlo method is also possible. We have studied Japanese phantoms in two procedures, mathematical phantom and 'symbol phantoms'. Our mathematical phantoms realize their height and body weights but does not hold some of organ weights, which were measured by TANAKA and KAWAMURA. The symbol phantom can solve this discrepancy and realize a realistic phantom, although it remains problems of authorization and normalization. Errors were estimated for internal dose calculations and it was pointed out that to use realistic organ weights and parameters of kinetics was important competitively to reduce uncertainty of the results. (author)

  4. Importance of pre-treatment radiation absorbed dose estimation for radioimmunotherapy of non-Hodgkin's lymphoma

    International Nuclear Information System (INIS)

    Non-Hodgkin's lymphoma I-131 radioimmunotherapy data were analyzed to determine whether a predictive relationship exists between radiation absorbed doses calculated from biodistribution studies and doses derived from patient size. Radioactivity treatment administrations scaled to patient size (MBq/kg or MBq/m2) or fixed MBq doses do not produce consistent radiation absorbed dose to critical organs. Treatment trials that do not provide dose estimates for critical normal organs are less likely to succeed in identifying a clinical role for radioimmunotherapy

  5. 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)

  6. Electron scattering effects on absorbed dose measurements with LiF-dosemeters

    International Nuclear Information System (INIS)

    The investigation deals with absorbed dose measurements with solid wall-less dosemeters. Electron scattering complicates both measurement of absorbed dose and its theoretical interpretation. The introduction of the dosemeter in a medium causes perturbations of the radiation field. This perturbation and its effect on the distribution of the absorbed dose inside the dosemeter is studied. Plane-parallel LiF-teflon dosemeters (0.005 - 0.1 g.cm-2) are irradiated by a photon beam (137Cs) in different media. The investigation shows that corrections must be made for perturbations caused by electron scattering phenomena. Correction factors are given for use in accurate absorbed dose determinations with thermoluminescent dosemeters. (Auth.)

  7. Calibration procedure for thermoluminescent dosemeters in water absorbed doses for Iridium-192 high dose rate sources

    International Nuclear Information System (INIS)

    Thermoluminescent dosimeters are used in brachytherapy services quality assurance programs, with the aim of guaranteeing the correct radiation dose supplied to cancer patients, as well as with the purpose of evaluating new clinical procedures. This work describes a methodology for thermoluminescent dosimeters calibration in terms of absorbed dose to water for 192Ir high dose rate sources. The reference dose used is measured with an ionization chamber previously calibrated for 192Ir energy quality, applying the methodology proposed by Toelli. This methodology aims to standardizing the procedure, in a similar form to that used for external radiotherapy. The work evolves the adaptation of the TRS-277 Code of the International Atomic Energy Agency, for small and big cavities, through the introduction for non-uniform experimental factor, for the absorbed dose in the neighborhood of small brachytherapy sources. In order to simulate a water medium around the source during the experimental work, an acrylic phantom was used. It guarantees the reproducibility of the ionization chamber and the thermoluminescent dosimeter's location in relation to the radiation source. The values obtained with the ionization chamber and the thermoluminescent dosimeters, exposed to a 192Ir high dose rate source, were compared and correction factors for different source-detector distances were determined for the thermoluminescent dosimeters. A numeric function was generated relating the correction factors and the source-detector distance. These correction factors are in fact the thermoluminescent dosimeter calibration factors for the 192Ir source considered. As a possible application of this calibration methodology for thermoluminescent dosimeters, a practical range of source-detector distances is proposed for quality control of 192Ir high dose rate sources. (author)

  8. Standardization of high-dose measurement of electron and gamma ray absorbed doses and dose rates

    International Nuclear Information System (INIS)

    Intense electron beams and gamma radiation fields are used for sterilizing medical devices, treating municipal wastes, processing industrial goods, controlling parasites and pathogens, and extending the shelf-life of foods. Quality control of such radiation processes depends largely on maintaining measurement quality assurance through sound dosimetry procedures in the research leading to each process, in the commissioning of that process, and in the routine dose monitoring practices. This affords documentation as to whether satisfactory dose uniformity is maintained throughout the product and throughout the process. Therefore, dosimetry at high doses and dose rates must in many radiation processes be standardized carefully, so that 'dosimetry release' of a product is verified. This standardization is initiated through preliminary dosimetry intercomparison studies such as those sponsored recently by the IAEA. This is followed by establishing periodic exercises in traceability to national or international standards of absorbed dose and dose rate. Traceability is achieved by careful selection of dosimetry methods and proven reference dosimeters capable of giving sufficiently accurate and precise 'transfer' dose assessments: (1) they must be calibrated or have well-established radiation-yield indices; (2) their radiation response characteristics must be reproducible and cover the dose range of interest; (3) they must withstand the rigours of back-and-forth mailing between a central standardizing laboratory and radiation processing facilities, without excessive errors arising due to instabilities, dosimeter batch non-uniformities, and environmental and handling stresses. (author)

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

    OpenAIRE

    Perevertaylo V. L.

    2010-01-01

    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.

  10. 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

  11. Photon spectrum and absorbed dose in brain tumor

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    Öğretici, Akın; Akbaş, Uğur; Köksal, Canan; Bilge, Hatice

    2016-01-01

    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 1.39cGy and for IMRT it is 8.48cGy, for a pregnant breast cancer woman who received radiation treatment of 50Gy. 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 5cm. The mean fetal dose from 3-D CRT is 1.39cGy and IMRT is 8.48cGy, 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. PMID:26831923

  14. Evaluation of lens absorbed dose with Cone Beam IGRT procedures.

    Science.gov (United States)

    Palomo, R; Pujades, M C; Gimeno-Olmos, J; Carmona, V; Lliso, F; Candela-Juan, C; Vijande, J; Ballester, F; Perez-Calatayud, J

    2015-12-01

    The purpose of this work is to evaluate the absorbed dose to the eye lenses due to the cone beam computed tomography (CBCT) system used to accurately position the patient during head-and-neck image guided procedures. The on-board imaging (OBI) systems (v.1.5) of Clinac iX and TrueBeam (Varian) accelerators were used to evaluate the imparted dose to the eye lenses and some additional points of the head. All CBCT scans were acquired with the Standard-Dose Head protocol from Varian. Doses were measured using thermoluminescence dosimeters (TLDs) placed in an anthropomorphic phantom. TLDs were calibrated at the beam quality used to reduce their energy dependence. Average dose to the lens due to the OBI systems of the Clinac iX and the TrueBeam were 0.71  ±  0.07 mGy/CBCT and 0.70  ±  0.08 mGy/CBCT, respectively. The extra absorbed dose received by the eye lenses due to one CBCT acquisition with the studied protocol is far below the 500 mGy threshold established by ICRP for cataract formation (ICRP 2011 Statement on Tissue Reactions). However, the incremental effect of several CBCT acquisitions during the whole treatment should be taken into account. PMID:26457404

  15. 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.

  16. 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.

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

    International Nuclear Information System (INIS)

    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

  18. 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.

  19. Some comments on the concept of absorbed dose

    International Nuclear Information System (INIS)

    The main physical quantity for the evaluation of the induced effects by radiation ionizing is absorbed dose. ICRU report 51 defines this concept as quantity dε divided by dm, where dε is the mean energy imparted by radiation ionizing to matter of mass dm. However, nothing is said about the average operation concerning the stochastic energy imparted ε. Nevertheless, because considers the sum of all changes of rest mass of the involved nuclei and elementary particles in all interactions which occur within the mass (i.e. nuclear reactions and transformations of elementary particles), the average operation can not be done with an equilibrium statistical operator, rather, this has to be defined with a non-equilibrium statistical operator, therefore, absorbed dose is a function dependent on time. Furthermore, we present a discussion to clarify the equilibrium radiation and charged particle equilibrium within the context of thermodynamic equilibrium. (Author)

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

    International Nuclear Information System (INIS)

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

  1. 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.

  2. 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...... radiochromic dye film dosimeters placed at various depths in a quartz glass pulse radiolysis cell. The cell was irradiated with 30 ns pulses from a field-emission electron accelerator having a broad spectrum with a maximum energy of ≈MeV. The measured three-dimensional dose distributions showed sharp gradients...

  3. Specific absorbed fractions and S-factors for calculating absorbed dose to embryo and fetus

    International Nuclear Information System (INIS)

    The variation of specific absorbed fractions from maternal tissues to embryo/fetus is investigated for four different target masses and geometries. S-factors are calculated for selected radionuclides assumed to be distributed uniformly in fetal tissues represented by spheres from 1 mg to 4 kg. As an example, the dose to fetal tissues for iodine-131 and iron-59 is estimated based on human biokinetic data for various stages of pregnancy. 24 references, 4 tables

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

    Energy Technology Data Exchange (ETDEWEB)

    Clasie, Ben; Wroe, Andrew; Kooy, Hanne; Depauw, Nicolas; Flanz, Jay; Paganetti, Harald; Rosenfeld, Anatoly [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States) and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, 2522 (Australia); Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, New South Wales, 2522 (Australia)

    2010-01-15

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

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

    Science.gov (United States)

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

    2015-01-01

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

  6. 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)

  7. Variations in absorbed doses from 59Fe in different diseases

    International Nuclear Information System (INIS)

    The biokinetics of radiopharmaceuticals administered in vivo may vary considerably with changes in organ functions. They studied the variations in absorbed doses from 59Fe in 207 patients with different diseases, in whom ferrokinetic investigations were performed for diagnostic purposes. Radiation doses to the bone marrow were highest in patients with deserythropoietic anemias (mean 38 nSv/Bq, range 19 - 57 nSv/Bq) and in hemolytic anemias (mean 21 nSv/Bq, range 7 - 35 nSv/Bq), whereas lower and rather constant values were found in other diseases (mean values between 9 and 13 nSv/Bq). The highest organ doses, the greatest differences with respect to diagnosis and also the largest variations within each group of patients were found for liver and spleen (e. g. in aplastic anemia; liver: 66 nSv/Bq, range 29 - 104 nSv/Bq; spleen: 57 nSv/Bq, range 34 - 98 nSv/Bq. In iron deficiency; liver: 13 nSv/Bq range 12 - 14 nSv/q; spleen: 19 nSv/Bq, range 18 - 20 nSv/Bq). Lower organ doses and smaller variations within and between the groups of patients were found for the gonads (means 3 - 7 nSv/Bq), the kidneys (means 10 - 13 nSv/Bq), the bone (means 4 - 7 nSv/Bq), the lung (means 8 - 12 nSv/Bq), and the total body (means 6 - 8 nSv/Bq). In patients with chronic bleeding absorbed doses decrease concomitantly to the extent of blood loss. The D/sub E/ is not markedly affected by the variations in organ doses but is fairly constant for different diseases. 16 references, 1 figure, 3 tables

  8. 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-...

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

    International Nuclear Information System (INIS)

    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)

  10. 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)

  11. 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.

  12. Influence of radioactive contaminants on absorbed dose estimates for radiopharmaceuticals

    International Nuclear Information System (INIS)

    Several popular radiopharmaceutical products contain low levels of radioactive contaminants. These contaminants increase the radiation absorbed dose to the patient without any increased benefit and, in some cases, with a decrease in image quality. The importance of a contaminant to the radiation dosimetry picture is a function of 1) the contaminant level, 2) the physical half-life of the contaminant, 3) the organ uptake and the biological half-time of the contaminant in the various body systems, and 4) the decay mode, energy, etc. of the contaminant. The general influence of these parameters is discussed in this paper; families of curves are included that reflect the changing importance of contaminant dosimetry with respect to the primary radionuclide as a function of these variables. Several specific examples are also given of currently used radiopharmaceutical products which can contain radioactive contaminants (I-123, In-111, Tl-201, Ir-191m, Rb-82, Au-195m). 7 references, 8 figures, 4 tables

  13. 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.

  14. 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)

  15. External Auditing on Absorbed Dose Using a Solid Water Phantom for Domestic Radiotherapy Facilities

    International Nuclear Information System (INIS)

    We report the results of an external audit on the absorbed dose of radiotherapy beams independently performed by third parties. For this effort, we developed a method to measure the absorbed dose to water in an easy and convenient setup of solid water phantom. In 2008, 12 radiotherapy centers voluntarily participated in the external auditing program and 47 beams of X-ray and electron were independently calibrated by the third party's American Association of Physicists in Medicine (AAPM) task group (TG)-51 protocol. Even though the AAPM TG-51 protocol recommended the use of water, water as a phantom has a few disadvantages, especially in a busy clinic. Instead, we used solid water phantom due to its reproducibility and convenience in terms of setup and transport. Dose conversion factors between solid water and water were determined for photon and electron beams of various energies by using a scaling method and experimental measurements. Most of the beams (74%) were within ±2% of the deviation from the third party's protocol. However, two of 20 X-ray beams and three of 27 electron beams were out of the tolerance (±3%), including two beams with a >10% deviation. X-ray beams of higher than 6 MV had no conversion factors, while a 6 MV absorbed dose to a solid water phantom was 0.4% less than the dose to water. The electron dose conversion factors between the solid water phantom and water were determined: The higher the electron energy, the less is the conversion factor. The total uncertainty of the TG-51 protocol measurement using a solid water phantom was determined to be ±1.5%. The developed method was successfully applied for the external auditing program, which could be evolved into a credential program of multi-institutional clinical trials. This dosimetry saved time for measuring doses as well as decreased the uncertainty of measurement possibly resulting from the reference setup in water.

  16. External Auditing on Absorbed Dose Using a Solid Water Phantom for Domestic Radiotherapy Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chang Heon; Kim, Jung In; Park, Jong Min; Park, Yang Kyun; Ye, Sung Joon [Medical Research Center, Seoul National University College of Medicine, Seoul (Korea, Republic of); Cho, Kun Woo; Cho, Woon Kap [Radiation Research, Korean Institute of Nuclear Safety, Daejeon (Korea, Republic of); Lim, Chun Il [Korea Food and Drug Administration, Seoul (Korea, Republic of)

    2010-11-15

    We report the results of an external audit on the absorbed dose of radiotherapy beams independently performed by third parties. For this effort, we developed a method to measure the absorbed dose to water in an easy and convenient setup of solid water phantom. In 2008, 12 radiotherapy centers voluntarily participated in the external auditing program and 47 beams of X-ray and electron were independently calibrated by the third party's American Association of Physicists in Medicine (AAPM) task group (TG)-51 protocol. Even though the AAPM TG-51 protocol recommended the use of water, water as a phantom has a few disadvantages, especially in a busy clinic. Instead, we used solid water phantom due to its reproducibility and convenience in terms of setup and transport. Dose conversion factors between solid water and water were determined for photon and electron beams of various energies by using a scaling method and experimental measurements. Most of the beams (74%) were within {+-}2% of the deviation from the third party's protocol. However, two of 20 X-ray beams and three of 27 electron beams were out of the tolerance ({+-}3%), including two beams with a >10% deviation. X-ray beams of higher than 6 MV had no conversion factors, while a 6 MV absorbed dose to a solid water phantom was 0.4% less than the dose to water. The electron dose conversion factors between the solid water phantom and water were determined: The higher the electron energy, the less is the conversion factor. The total uncertainty of the TG-51 protocol measurement using a solid water phantom was determined to be {+-}1.5%. The developed method was successfully applied for the external auditing program, which could be evolved into a credential program of multi-institutional clinical trials. This dosimetry saved time for measuring doses as well as decreased the uncertainty of measurement possibly resulting from the reference setup in water.

  17. Analysis of surface absorbed dose in X-ray grating interferometry

    International Nuclear Information System (INIS)

    Highlights: • Theoretical framework for dose estimation in X-ray grating interferometry. • Potential dose reduction of X-ray grating interferometry compared to conventional radiography. • Guidelines for optimization of X-ray grating interferometry for dose-sensitive applications. • Measure to compare various existing X-ray phase contrast imaging techniques. - Abstract: X-ray phase contrast imaging using grating interferometry has shown increased contrast over conventional absorption imaging, and therefore the great potential of dose reduction. The extent of the dose reduction depends on the geometry of grating interferometry, the photon energy, the properties of the sample under investigation and the utilized detector. These factors also determine the capability of grating interferometry to distinguish between different tissues with a specified statistical certainty in a single raw image. In this contribution, the required photon number for imaging and the resulting surface absorbed dose are determined in X-ray grating interferometry, using a two-component imaging object model. The presented results confirm that compared to conventional radiography, phase contrast imaging using grating interferometry indeed has the potential of dose reduction. And the extent of dose reduction is strongly dependent on the imaging conditions. Those results provide a theoretical framework for dose estimation under given imaging conditions before experimental trials, and general guidelines for optimization of grating interferometry for those dose-sensitive applications

  18. Scaling neutron absorbed dose distributions from one medium to another

    International Nuclear Information System (INIS)

    Central axis depth dose (CADD) and off-axis absorbed dose ratio (OAR) measurements were made in water, muscle and whole skeletal bone TE-solutions, mineral oil and glycerin with a clinical neutron therapy beam. These measurements show that, for a given neutron beam quality and field size, there is a universal CADD distribution at infinity if the depth in the phantom is expressed in terms of appropriate scaling lengths. These are essentially the kerma-weighted neutron mean free paths in the media. The method used in ICRU No. 26 to scale the CADD by the ratio of the densities is shown to give incorrect results. the OAR's measured in different media at depths proportional to the respective mean free paths were also found to be independent of the media to a good approximation. It is recommended that relative CADD and OAR measurements be performed in water because of its universality and convenience. A table of calculated scaling lengths is given for various neutron energy spectra and for various tissues and materials of practical importance in neutron dosimetry

  19. 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

  20. 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.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2005-12-01

    An international collaboration was organized to undertake a dosimetry exchange to enable the future combination of clinical data from different centers conducting neutron capture therapy trials. As a first step (Part I) the dosimetry group from the Americas, represented by MIT, visited the clinical centers at Studsvik (Sweden), VTT Espoo (Finland), and the Nuclear Research Institute (NRI) at Rez (Czech Republic). A combined VTT/NRI group reciprocated with a visit to MIT. Each participant performed a series of dosimetry measurements under equivalent irradiation conditions using methods appropriate to their clinical protocols. This entailed in-air measurements and dose versus depth measurements in a large water phantom. Thermal neutron flux as well as fast neutron and photon absorbed dose rates were measured. Satisfactory agreement in determining absorbed dose within the experimental uncertainties was obtained between the different groups although the measurement uncertainties are large, ranging between 3% and 30% depending upon the dose component and the depth of measurement. To improve the precision in the specification of absorbed dose amongst the participants, the individually measured dose components were normalized to the results from a single method. Assuming a boron concentration of 15 microg g(-1) that is typical of concentrations realized clinically with the boron delivery compound boronophenylalanine-fructose, systematic discrepancies in the specification of the total biologically weighted dose of up to 10% were apparent between the different groups. The results from these measurements will be used in future to normalize treatment plan calculations between the different clinical dosimetry protocols as Part II of this study. PMID:16475772

  3. 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...

  4. Absorbed XFEL dose in the components of the LCLS X-Ray Optics

    Energy Technology Data Exchange (ETDEWEB)

    Hau-Riege, S

    2005-09-27

    We list the materials that are anticipated to be placed into the Linac Coherent Light Source (LCLS) x-ray free electron laser (XFEL) beam line, their positions, and the absorbed dose, and compare this dose with anticipated damage thresholds.

  5. 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)

  6. Simultaneous measurements of absorbed dose and linear energy transfer in therapeutic proton beams

    Science.gov (United States)

    Granville, Dal A.; Sahoo, Narayan; Sawakuchi, Gabriel O.

    2016-02-01

    The biological response resulting from proton therapy depends on both the absorbed dose in the irradiated tissue and the linear energy transfer (LET) of the beam. Currently, optimization of proton therapy treatment plans is based only on absorbed dose. However, recent advances in proton therapy delivery have made it possible to vary the LET distribution for potential therapeutic gain, leading to investigations of using LET as an additional parameter in plan optimization. Having a method to measure and verify both absorbed dose and LET as part of a quality assurance program would be ideal for the safe delivery of such plans. Here we demonstrated the potential of an optically stimulated luminescence (OSL) technique to simultaneously measure absorbed dose and LET. We calibrated the ratio of ultraviolet (UV) to blue emission intensities from Al2O3:C OSL detectors as a function of LET to facilitate LET measurements. We also calibrated the intensity of the blue OSL emission for absorbed dose measurements and introduced a technique to correct for the LET-dependent dose response of OSL detectors exposed to therapeutic proton beams. We demonstrated the potential of our OSL technique by using it to measure LET and absorbed dose under new irradiation conditions, including patient-specific proton therapy treatment plans. In the beams investigated, we found the OSL technique to measure dose-weighted LET within 7.9% of Monte Carlo-simulated values and absorbed dose within 2.5% of ionization chamber measurements.

  7. Absorbed dose due to radioiodine therapy by organs of patients with hyperthyroidism

    International Nuclear Information System (INIS)

    The dose absorbed by organs of patients with hyperthyroidism treated with 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 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

  8. Influence of absorbed dose and deep traps on thermoluminescence response: A numerical simulation

    International Nuclear Information System (INIS)

    Numerical simulations based on standard rate equations are carried out to study the dependence of the thermoluminescence (TL) response on the absorbed dose. The model, which includes thermally stimulated exo-electronic emission (TSEE), uses three electron traps - two active and one thermally disconnected (TD) - and one deep hole trap acting as a recombination centre. After instantaneous creation of a given dose of electron-hole pairs, one first follows isothermal recombination and trap filling before simulating the TL readout. Influence of TD traps and specific effects due to trap saturation are illustrated. A systematic study of the TL response is performed in wide ranges of the determining parameters. The dose dependence is found to be quadratic, linear or intermediate according to their relative values. Results are explained in terms of recombination-trapping competition, trap occupancy and in relation with the presence of TSEE. (authors)

  9. 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...

  10. Thermoluminescent dosemeters for determining the energy absorbed during X-ray radiography of the vertebral column

    International Nuclear Information System (INIS)

    The dose and absorbed energy during normal diagnostic X-ray of various sections of the vertebral column were determined with LiF-dosemeters in a phantom. The paper describes a method to be used to determine integral doses from the dose measurements. The energy absorbed for one X-ray picture of the vertebral column is between 5 and 30 mJ. Compared to other diagnostical X-rays the quantity of the energy absorbed during X-ray of the vertebral column is rather high and is only reached by X-rays in the pelvic region. The speculations on the rate of incidence of malignent neoplasms on the basis of diagnostical X-ray of the vertebral column reveal a value of 50 per 60 x 106 persons. This value is likely to overestimate the risk, seems, however, to be low in comparison to other risks of every day life (traffic accident, mountainering, etc). (orig./HP)

  11. 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...

  12. Determination of the effective dose equivalent in gynecologic radium therapy

    International Nuclear Information System (INIS)

    In this study, the authors describe how to determine the effective dose equivalent absorbed by occupationally exposed persons during a gynecologic radium therapy. The observed irradiation conditions of the physician and the medical staff are approximated by a standard geometry, for which conversion factors between the measured personal dose, the effective dose equivalent and different organ doses, respectively, are calculated. The results are job-specific conversion factors between dose to a personal dosimeter and the effective dose equivalent for the occupationally exposed persons involved. According to the individual tasks, these factors are between 0.59 and 1.13. (orig.)

  13. 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.

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

    International Nuclear Information System (INIS)

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

  15. Biological indicators for radiation absorbed dose: a review

    International Nuclear Information System (INIS)

    Biological dosimetry has an important role to play in assessing the cumulative radiation exposure of persons working with radiation and also in estimating the true dose received during accidents involving external and internal exposure. Various biodosimetric methods have been tried to estimate radiation dose for the above purposes. Biodosimetric methods include cytogenetic, immunological and mutational assays. Each technique has certain advantages and disadvantages. We present here a review of each technique, the actual method used for detection of dose, the sensitivity of detection and its use in long term studies. (author)

  16. 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...

  17. Measurement of absorbed dose to water for low and medium energy x-rays

    International Nuclear Information System (INIS)

    Full text: Over the last decade, the treatment of superficial or intercavitary malignancies with medium-energy x-rays has regained popularity. This development puts renewed and increased emphasis on the importance of accurate dosimetry in this energy range. An appreciable number of publications dealing with various aspects of dosimetry in medium-energy x-ray beams has appeared and several protocols for the dosimetry of medium-energy x-ray appeared which led to the publication of a comparison between the various protocols. Attempts were made to model x-ray radiotherapy units by Monte Carlo methods, a method originally developed for high-energy treatment systems. In-phantom dosimetry for medium-energy x-rays suffers from the lack of a primary standard which would allow direct determination of the water absorbed dose. Attempts at a direct measurement of the water absorbed dose were made employing water calorimetry. These attempts suffered from the unknown energy dependence of the chemical yield for ferrous sulfate dosimetry, or from insufficient knowledge of the calorimetric heat defect. In the absence of a direct method, two different approaches have mainly been made. In one of these an ionisation chamber calibrated in free air in terms of air kerma is positioned at reference depth inside the water phantom. The absorbed dose to water is obtained by conversion of the air kerma measured in the water phantom to water kerma or, which is essentially equivalent in this energy range, to absorbed dose to water. When this method is used, correction factors have to be applied, which have to take into account i) the differences in the properties of the radiation field used for calibration in free air and of that inside the phantom and ii) the modification of the in-phantom radiation field caused by the presence of the ionisation chamber with its air cavity and with non water-equivalent walls and chamber stem. The other approach is to start with the measurement of absorbed dose

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

    International Nuclear Information System (INIS)

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

  19. 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

  20. Evaluation of the absorbed dose to the lungs due to Xe133 and Tc99m (MAA)

    International Nuclear Information System (INIS)

    The absorbed dose in lungs of an adult patient has been evaluated using the biokinetics of radiopharmaceuticals containing Xe133 or Tc99m (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 133Xe is 0.00104 mGy/MBq. Here, the absorbed dose due to remaining tissue, included in the 133Xe biokinetics is not significant. The absorbed dose in the lungs, due Tc99m (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 Tc99m biokinetics. Here, the absorbed dose is very significant to be overlooked. The dose contribution is mainly due to photons emitted by the liver. (Author)

  1. Effects of body and organ size on absorbed dose: there is no standard patient

    International Nuclear Information System (INIS)

    The problem of estimating the absorbed dose to organs and tissues of the human body due to the presence of a radiopharmaceutical in one or more organs is discussed. Complications are introduced by the fact that the body is not homogeneous and in many cases the organ shapes are not regular. Publications of the MIRD Committee have provided a direct means of estimating the absorbed dose (or absorbed fraction) for a number of radioisotopes. These estimates are based on Monte Carlo calculations for monoenergetic photons distributed uniformly in organs of an adult phantom. The medical physicist finds that his patient does not resemble the adult phantom. In addition, the absorbed fractions for the adult are not reasonable values for the child. This paper examines how these absorbed fraction estimates apply to a nonstandard patient

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

    International Nuclear Information System (INIS)

    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

  3. 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.

  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. {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

  6. Preclinical Studies of 68Ga-DOTATOC: Biodistribution Assessment in Syrian Rats and Evaluation of Absorbed Dose in Human Organs

    Directory of Open Access Journals (Sweden)

    mojdeh naderi

    2016-01-01

    Full Text Available Objective(s: Gallium-68 DOTA-DPhe1-Tyr3-Octreotide (68Ga-DOTATOC has been applied by several European centers for the treatment of a variety of human malignancies. Nevertheless, definitive dosimetric data are yet unavailable. According to the Society of Nuclear Medicine and Molecular Imaging, researchers are investigating the safety and efficacy of this radiotracer to meet Food and Drug Administration requirements. The aim of this study was to introduce the optimized procedure for 68Ga-DOTATOC preparation, using a novel germanium-68 (68Ge/68Ga generator in Iran and evaluate the absorbed doses in numerous organs with high accuracy. Methods: The optimized conditions for preparing the radiolabeled complex were determined via several experiments by changing the ligand concentration, pH, temperature and incubation time. Radiochemical purity of the complex was assessed, using high-performance liquid chromatography and instant thin-layer chromatography. The absorbed dose of human organs was evaluated, based on biodistribution studies on Syrian rats via Radiation Absorbed Dose Assessment Resource Method. Results: 68Ga-DOTATOC was prepared with radiochemical purity of >98% and specific activity of 39.6 MBq/nmol. The complex demonstrated great stability at room temperature and in human serum at 37°C at least two hours after preparation. Significant uptake was observed in somatostatin receptor-positive tissues such as pancreatic and adrenal tissues (12.83 %ID/g and 0.91 %ID/g, respectively. Dose estimations in human organs showed that the pancreas, kidneys and adrenal glands received the maximum absorbed doses (0.105, 0.074 and 0.010 mGy/MBq, respectively. Also, the effective absorbed dose was estimated at 0.026 mSv/MBq for 68Ga-DOTATOC. Conclusion: The obtained results showed that 68Ga-DOTATOC can be considered as an effective agent for clinical PET imaging in Iran.

  7. 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)

  8. 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.

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

    International Nuclear Information System (INIS)

    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

  10. 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

  11. 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.

  12. 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

    2016-07-21

    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. PMID:27366861

  13. Determining factors for high performance silicone rubber microwave absorbing materials

    International Nuclear Information System (INIS)

    Silicone rubber microwave absorbing materials (RMAMs) based on ferrite as the major absorbent were prepared by the mechanical blending method. The determining factors for the complex permittivity, complex permeability, and reflectivity of RMAM were thoroughly investigated with various samples including different crystal structures of Ba-ferrite (M-type, W-type, and Y-type), the ferrite with doped elements (Ba, Sr), the materials' thickness, the combination ratio of ferrite and carbonyl iron. The effects of surface modification and loading amount of ferrite on the mechanical properties, processing performance, and absorbing property of RMAM were also assessed. The results show that W-type Ba-ferrite based RMAM exhibits better absorbing property at high frequencies (8-18 GHz) than the other two barium ferrites (M-type and Y-type) based ones, and the absorbing property of RMAM based on Sr-ferrite is best. As the thickness of RMAM and the amount of absorbents increase, the absorption peak moves toward low frequency, the absorption frequency bandwidth is narrowed, and the reflectivity first decreases and later increases. The optimum thickness is 1.5-1.7 mm, and the amount of ferrite is 450 parts per hundreds of rubber (phr). Surface modification of the absorbent with silane coupling agent could improve the mechanical properties and processing performance of RMAM. It is concluded that there will be a synergistic effect when carbonyl iron (CI) is used in combination with Sr-ferrite (Sr-W) in an appropriate proportion. When the total volume fraction of absorbents is 51%, the optimum ratio of Cl to Sr-W is 17:34, the absorption frequency bandwidth (<-10 dB) is about 8 GHz, and the absorption area is -99 dB. - Highlights: → W-type ferrite exhibits better absorbing property than M-type and Y-type at 8-18 GHz. → Sr-W based RMAM has best absorbing property of Ba- and Sr-ferrite. → The optimum thickness of RMAM is 1.5-1.7 mm, and the amount of ferrite is 450 phr.

  14. 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.

  15. Independent absorbed-dose calculation using the Monte Carlo algorithm in volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    To report the result of independent absorbed-dose calculations based on a Monte Carlo (MC) algorithm in volumetric modulated arc therapy (VMAT) for various treatment sites. All treatment plans were created by the superposition/convolution (SC) algorithm of SmartArc (Pinnacle V9.2, Philips). The beam information was converted into the format of the Monaco V3.3 (Elekta), which uses the X-ray voxel-based MC (XVMC) algorithm. The dose distribution was independently recalculated in the Monaco. The dose for the planning target volume (PTV) and the organ at risk (OAR) were analyzed via comparisons with those of the treatment plan. Before performing an independent absorbed-dose calculation, the validation was conducted via irradiation from 3 different gantry angles with a 10- × 10-cm2 field. For the independent absorbed-dose calculation, 15 patients with cancer (prostate, 5; lung, 5; head and neck, 3; rectal, 1; and esophageal, 1) who were treated with single-arc VMAT were selected. To classify the cause of the dose difference between the Pinnacle and Monaco TPSs, their calculations were also compared with the measurement data. In validation, the dose in Pinnacle agreed with that in Monaco within 1.5%. The agreement in VMAT calculations between Pinnacle and Monaco using phantoms was exceptional; at the isocenter, the difference was less than 1.5% for all the patients. For independent absorbed-dose calculations, the agreement was also extremely good. For the mean dose for the PTV in particular, the agreement was within 2.0% in all the patients; specifically, no large difference was observed for high-dose regions. Conversely, a significant difference was observed in the mean dose for the OAR. For patients with prostate cancer, the mean rectal dose calculated in Monaco was significantly smaller than that calculated in Pinnacle. There was no remarkable difference between the SC and XVMC calculations in the high-dose regions. The difference observed in the low-dose regions may

  16. A study on absorbed dose in the breast tissue using geant4 simulation for mammography

    International Nuclear Information System (INIS)

    As the breast cancer rate is increasing fast in Korean women, people pay more attention to mammography and number of mammography have been increasing dramatically over the last few years. Mammography is the only means to diagnose breast cancer early, but harms caused by radiation exposure shouldn't be overlooked. Therefore, it is important to calculate the radiation dose being absorbed into the breast tissue during the process of mammography for a protective measure against radiation exposure. Because it is impossible to directly measure the radiation dose being absorbed into the human body, statistical calculation methods are commonly used, and most of them are supposed to simulate the interaction between radiation and matter by describing the human body internal structure with anthropomorphic phantoms. However, a simulation using Geant4 Code of Monte Carlo Method, which is well-known as most accurate in calculating the absorbed dose inside the human body, helps calculate exact dose by recreating the anatomical human body structure as it is through the DICOM file of CT. To calculate the absorbed dose in the breast tissue, therefore, this study carried out a simulation using Geant4 Code, and by using the DICOM converted file provided by Geant4, this study changed the human body structure expressed on the CT image data into geometry needed for this simulation. Besides, this study attempted to verify if the dose calculation of Geant4 interlocking with the DICOM file is useful, by comparing the calculated dose provided by this simulation and the measured dose provided by the PTW ion chamber. As a result, under the condition of 28kVp/190mAs, the Difference(%) between the measured dose and the calculated dose was found to be 0.08 %∼0.33 %, and at 28 kVp/70 mAs, the Difference(%) of dose was 0.01 %∼0.16 %, both of which showed results within 2%, the effective difference range. Therefore, this study found out that calculation of the absorbed dose using Geant4

  17. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Hau-Riege, Stefan

    2010-12-03

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

  19. Relationship between biologic tissue heterogeneity and absorbed dose distribution in therapy of oncologic patients with cyclotron U-120 fast neutrons

    International Nuclear Information System (INIS)

    Effect of biological tissue heterogeneity on the absorbed dose distribution of U-120 cyclotron fast neutron beam was studied by estimation and experimental method. It was found that adipose and bone tissues significantly changes the pattern of neutron absorbed dose distribution in patient body. Absorbed dose in adipose layer increase by 20% as compared to the dose in soft biological tissue. Approximation method for estimation of the absorbed dose distribution of fast neutrons in heterogeneities was proposed which could be applied in the dosimetric planning of U-120 cyclotron neutron therapy of neoplasms

  20. A study on the absolute measurement of β-ray absorbed dose in the skin depth

    International Nuclear Information System (INIS)

    The absolute measurement of β ray absorbed dose in the skin depth located at the certain distance from the radiation source (90Sr + 90Y, 204TI, 147Pm) recommended by the International Standardization Organization is performed by using an extrapolation chamber in the range of several mGy/h. Since one of critical points in measuring of absorbed dose is to make the environment in chamber similar to tissue, a new approach to the measurement of absorbed dose is proposed. The attenuation difference is minimized by deciding a window thickness such as the attenuation effect in chamber window becomes similar to that in the skin depth. A-150 tissue equivalent plastic, whose structure and density is very similar to tissue, is used for back material. The back scattering effect of both media is measured using the proposed method to calibrate the difference in back scattering effect between back material and tissue. For the measurement of back scattering effect of each material, an ionization chamber, whose structure is very similar to the extrapolation chamber and back material is replaceable, is made. Based on the results, β ray absorbed dose in the skin depth of 70 μm was measured as follows : 0.759 μGy/s (±3.78% ) for 90Sr + 90Y, 0.173 μGy/s (±4.17%) for 204TI and 0.088 μGy/s (±7.70%) for 147Pm. In order to evaluate the reliability of the proposed method, the absorbed dose measured in this study is compared to that measured in PTB (Physikalisch Technische Bundesanstalt) for the same β ray source. Although the proposed method gives slightly higher value, the difference is within 1%. In conclusion, the proposed method seems to make the measuring environment closer to tissue, even though the calibration factor yielded by the proposed method has a little effect on evaluation of absorbed dose

  1. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation

    International Nuclear Information System (INIS)

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of 192Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results indicate an

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

    International Nuclear Information System (INIS)

    Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm–10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from 125I, 169Yb and 192Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1–10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies w,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. (paper)

  3. Absorbed dose in ion beams: comparison of ionisation- and fluence-based measurements

    International Nuclear Information System (INIS)

    A direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionisation chamber is presented. Irradiations were performed using monoenergetic protons (142.66 MeV, φ=3x106 cm-2) and carbon ions (270.55 MeV u-1, φ=3x106 cm-2). It was found that absorbed dose to water values as determined by fluence measurements using FNTDs are, in case of protons, in good agreement (2.4 %) with ionisation chamber measurements, if slower protons and Helium secondaries were accounted for by an effective stopping power. For carbon, however, a significant discrepancy of 4.5 % was seen, which could not be explained by fragmentation, uncertainties or experimental design. The results rather suggest a W-value of 32.10 eV±2.6 %. Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not observed. FNTDs are able to yield correct dose estimation for protons. The assumption of a monoenergetic beam, even in the entrance channel, is invalid since slower protons and secondaries contribute significantly and an effective stopping power has to be employed. These corrections account for the discrepancies seen in the authors' previous experiments. Since the FNTD fluorescent track amplitude depends on the particle species and energy, the effective stopping power might be estimated from the intensity histogram of the particle tracks. For carbon ions, however, secondary particles did not fully account for the discrepancies found. Considering the detection efficiency of FNTD technology, it seems unlikely that a significant portion of tracks were not registered. This might stimulate discussions on the accuracy of the kQ,Q0 factor for carbon beams. Since the stopping power in this energy range is known quite accurately (1-2 %), one might question the currently used constant Wair value of 34.50 ± 0.52 eV (1.5 %)(14). The presented findings would imply a Wair value of 32.10±0.83 eV (2.6 %). This uncertainty includes all

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

    Science.gov (United States)

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

    2016-01-01

    Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue-equivalent properties. We investigated a commercially available 'microdiamond' detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1mm, thickness 1 x10(-3) mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17% (1 SD) (n = 11). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stop-ping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long-term stability and reproducibility. Based on micro-dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance. PMID:27074452

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

    OpenAIRE

    Bueno Vizcarra, Marta; Carrasco, P. (Paula); Jornet, N.; Muñoz Montplet, C.; Duch Guillen, María Amor

    2014-01-01

    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 Li-7-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 f...

  6. A method to efficiently simulate absorbed dose in radio-sensitive instrumentation components

    International Nuclear Information System (INIS)

    Components installed in tunnels of high-power accelerators are prone to radiation-induced damage and malfunction. Such machines are usually modeled in detail and the radiation cascades are transported through the three-dimensional models in Monte Carlo codes. Very often those codes are used to compute energy deposition in beam components or radiation fields to the public and the environment. However, sensitive components such as electronic boards or insulator cables are less easily simulated, as their small size makes dose scoring a (statistically) inefficient process. Moreover the process to decide their location is iterative, as in order to define where these will be safely installed, the dose needs to be computed, but to do so the location needs to be known. This note presents a different approach to indirectly asses the potential absorbed dose by certain components when those are installed within a given radiation field. The method consists first in finding the energy and particle-dependent absorbed dose to fluence response function, and then programming those in a radiation transport Monte Carlo code, so that fluences in vacuum/air can be automatically converted real-time into potential absorbed doses and then mapped in the same way as fluences or dose equivalent magnitudes

  7. 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...

  8. Exposure distribution, absorbed doses, and energy imparted for panoramic radiography using Orthopantomograph model OP 5

    International Nuclear Information System (INIS)

    The absorbed doses and energy imparted for the Orthopantomograph model OP 5 using two different collimators (0.9-1.3 X 33 mm2 and 0.6-0.9 X 39.5 mm2, respectively) were examined at 70 and 75 kV. The absorbed doses were estimated by thermoluminescence dosimetry in a sectioned phantom and by the energy imparted from measurements of areal exposure using a plane parallel transmission ionization chamber. The exposure distribution was surveyed on radiographic film. The anterior part of the parotid glands received the highest absorbed doses (2.4-3.2 mGy) when the wider collimator was used, with a decrease of two to three times when the narrower collimator was used. Other areas received absorbed doses of about 1.0 to 1.5 mGy or below. An increase of the kV from 70 to 75 had a minor influence. The energy imparted for the wider collimator was 0.6-0.8 and for the narrower collimator, 0.4-0.6 mJ

  9. Internal radiation absorbed dose estimation in human brain due to technetium-99m and iodine-131

    International Nuclear Information System (INIS)

    Internal dosimetry is a branch of medical physics that deals with the measurement of the internally absorbed dose by an organ after applying isotopes. In this study, internal radiation absorbed dose has been calculated for 99mTc and 131I, which are frequently used for functioning tests and therapeutic treatments of thyroid, respectively in these cases, some amount of isotopes are accumulated in other tissues like brain, which are very soft and cannot be regenerated if they are damaged. Using ionizing radiation inside the body and to ensure the safety of brain, the internal radiation absorbed dose has been calculated applying direct counting measurement. Accumulation of isotopes to target organ has been measured and this target organ is considered as primary target organ; also this organ is considered as source with respect to other organs. These organ counts have, been measured by computer-based scintillation system. The amount of exposure in brain has been measured with the help of the data obtained from the special set-up equipment, including NaI detector, radiation survey meter and water phantoms of various sizes. Absorbed dose in brain for each isotope has been calculated by applying time-activity curve analysis. Finally, these results have been compared with the data in ICRP l Reports 53 and 71. (author)

  10. Axial distribution of absorbed doses in fast neutron field at the RB reactor

    International Nuclear Information System (INIS)

    The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)

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

    Science.gov (United States)

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

    2014-12-01

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

  12. Absorbed 18F-FDG Dose to the Fetus During Early Pregnancy

    International Nuclear Information System (INIS)

    We describe a rare case of a woman who underwent 18F-FDG PET/CT during early pregnancy (fetus age, 10 wk). The fetal absorbed dose was calculated by taking into account the 18F-FDG fetal self-dose, photon dose coming from the maternal tissues, and CT dose received by both mother and fetus. Methods: The patient (weight, 71 kg) had received 296 MBq of 18F-FDG. Imaging started at 1 h, with unenhanced CT acquisition, followed by PET acquisition. From the standardized uptake value measured in fetal tissues, we calculated the total number of disintegrations per unit of injected activity. Monte Carlo analysis was then used to derive the fetal 18F-FDG self-dose, including positrons and self-absorbed photons. Photon dose from maternal tissues and CT dose were added to obtain the final dose. Results: The maximum standardized uptake value in fetal tissues was 4.5. Monte Carlo simulation showed that the fetal self-dose was 3.0 * 10-2 mGy/MBq (2.7 * 10-2 mGy/MBq from positrons and 0.3 * 10-2 mGy/MBq from photons). The estimated photon dose to the fetus from maternal tissues was 1.04*10-2 mGy/MBq. Accordingly, the specific 18F-FDG dose to the fetus was about 4.0 *10-2 mGy/MBq (11.8 mGy in this patient). The CT scan added a further 10 mGy. Conclusion: The dose to the fetus during early pregnancy can be as high as 4.0*10-2 mGy/MBq of 18F-FDG. Current dosimetric standards in early pregnancy may need to be revised. (authors)

  13. Adiabatic calorimeter for measuring absorbed dose of IHEP synchrotron secondary radiation

    International Nuclear Information System (INIS)

    An adiabatic calorimeter for measuring the value of absorbed dose of mixed radiation generated by 70 GeV proton synchrotron is described. The calorimetric system consists of a working body (a core) and a shell (a screen). The calorimeter adiabaticity is provided by the absence of the core-shell heat exchange by maintaining the shell temperature equal to the core temperature and, consequently, the whole energy generated in the core goes for its heating. The work showed the possibility of carrying out the adiabatic calorimetric measurements of absorbed dose of secondary radiation generated by un accelerated proton beam under the conditions of alternating magnetic and electric fields at the IHEP proton synchrotron at the average dose rate not less than 5x10-3 Wxkg-1

  14. Absorbed doses received by infants subjected to panoramic dental and cephalic radiographs

    International Nuclear Information System (INIS)

    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)

  15. 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)

  16. 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.

  17. 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. PMID:6339690

  18. Absorbed radiation doses in women undergone to PET-CT exams for cancer diagnosis

    International Nuclear Information System (INIS)

    The absorbed dose in several organs and the effective dose in patients submitted to PET-CT exams with the radiopharmaceutical 18F-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 18F-FDG PET-CT examinations and promoting the compliance with the radiation protection principles. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. 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.

  1. Comparison of the standards of absorbed dose to water of the OMH and the BIPM for 60Co γ rays

    International Nuclear Information System (INIS)

    A comparison of the standards of absorbed dose to water of the Orszagos Meresugyi Hivatal (OMH), Budapest, Hungary and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co radiation. The results show that the OMH and the BIPM standards for absorbed dose to water are in close agreement, the difference being within the estimated uncertainty. (authors)

  2. 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.

  3. Physiologically based pharmacokinetic modeling of inhaled radon to calculate absorbed doses in mice, rats, and humans

    International Nuclear Information System (INIS)

    This is the first report to provide radiation doses, arising from inhalation of radon itself, in mice and rats. To quantify absorbed doses to organs and tissues in mice, rats, and humans, we computed the behavior of inhaled radon in their bodies on the basis of a physiologically based pharmacokinetic (PBPK) model. It was assumed that radon dissolved in blood entering the gas exchange compartment is transported to any tissue by the blood circulation to be instantaneously distributed according to a tissue/blood partition coefficient. The calculated concentrations of radon in the adipose tissue and red bone marrow following its inhalation were much higher than those in the others, because of the higher partition coefficients. Compared with a previous experimental data for rats and model calculation for humans, the present calculation was proved to be valid. Absorbed dose rates to organs and tissues were estimated to be within the range of 0.04-1.4 nGy (Bqm-3)-1 day-1 for all the species. Although the dose rates are not so high, it may be better to pay attention to the dose to the red bone marrow from the perspective of radiation protection. For more accurate dose assessment, it is necessary to update tissue/blood partition coefficients of radon that strongly govern the result of the PBPK modeling. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Edward T.; Liu, Xin, E-mail: xinliu@mst.edu [Nuclear Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States); Hsieh, Jiang [GE Healthcare, Waukesha, Wisconsin 53188 (United States)

    2015-07-15

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

  5. The Effect of the Size of Radiotherapy Photon Beams on the Absorbed Dose to an Al2O3 Dosimeter

    Institute of Scientific and Technical Information of China (English)

    陈少文; 张文澜; 范丽仙; 唐强; 刘小伟

    2012-01-01

    The effect of the size of radiotherapy photon beams on the absorbed dose to an Al2O3 dosimeter was investigated using the Monte Carlo method. The EGSnrc/DOSRZnrc program code was used to simulate the absorbed dose to the Al2O3 dosimeter, as well as the absorbed dose to water at the corresponding position in the absence of the dosimeter. The incident beams were 60Co γ and 6 MV with a different beam radius ranging from 0.1 cm to 2 cm. Results revealed that the absorbed dose ratio factor depends on the size of the incident photon beam. When the radius of the incident beam is smaller than that of the dosimeter, the absorbed dose ratio factor decreases as the incident beam size increases. The absorbed dose ratio factor reaches its minimum when the radius of the incident beam is almost the same as that of the dosimeter. When the radius of the incident beam is larger than that of the dosimeter, the absorbed dose ratio factor increases as the incident beam size increases. The maximum difference among these absorbed dose ratio factors can be up to 14% in 60Co γ beams and 23% in 6 MV beams. However, when the size of the incident beam is much larger than that of the dosimeter, the effect of the incident beam size on the absorbed dose ratio factor becomes quite small. The maximum discrepancy between the absorbed dose ratio factors and the average value is not more than 1%.

  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. 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. Absorbed dose assessment in particle-beam irradiated metal-oxide and metal-nonmetal memristors

    Directory of Open Access Journals (Sweden)

    Knežević Ivan D.

    2012-01-01

    Full Text Available Absorbed dose was estimated after Monte Carlo simulation of proton and ion beam irradiation on metal-oxide and metal-nonmetal memristors. A memristive device comprises two electrodes, each of a nanoscale width, and a double-layer active region disposed between and in electrical contact with electrodes. Following materials were considered for the active region: titanium dioxide, zirconium dioxide, hafnium dioxide, strontium titanium trioxide and galium nitride. Obtained results show that significant amount of oxygen ion - oxygen and nonmetal ion - nonmetal vacancy pairs is to be generated. The loss of such vacancies from the device is believed to deteriorate the device performance over time. Estimated absorbed dose values in the memristor for different constituting materials are of the same order of magnitude because of the close values of treshold displacement energies for the investigated materials.

  9. 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)

  10. Distribution of absorbed dose in human eye simulated by SRNA-2KG computer code

    International Nuclear Information System (INIS)

    Rapidly increasing performances of personal computers and development of codes for proton transport based on Monte Carlo methods will allow, very soon, the introduction of the computer planning proton therapy as a normal activity in regular hospital procedures. A description of SRNA code used for such applications and results of calculated distributions of proton-absorbed dose in human eye are given in this paper. (author)

  11. Measurement of absorbed dose rate of gamma radiation for lead compounds

    Science.gov (United States)

    Rudraswamy, B.; Dhananjaya, N.; Manjunatha, H. C.

    2010-07-01

    An attempt has been made to estimate the absorbed dose rate using both theoretical and measured mass energy attenuation coefficient of gamma for the lead compounds such as PbNO 3, PbCl 2, PbO 2 and PbO using various gamma sources such as 22Na (511, 1274), 137Cs (661.6), 54Mn (835) and 60Co (1173, 1332 keV).

  12. 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.

  13. Calculation of the internal radiation absorbed dose of 123I-Annexin V

    International Nuclear Information System (INIS)

    To estimate absorbed doses by 123I-Annexin V in human, 125I-Annexin V was used as a radiotracer for measuring the distribution of radiolabeled Annexin V in mice. The standard Medical Internal Radiation Dose (MIRD) method was used by Mirdose-3 software in dosimetry estimation. The results show that liver and kidney received 2.77 x 10-3 and 2.71 x 10-3 mGy/MBq, respectively. The red marrow received 1.78 x 10-5 mGy/MBq, and the other organs received doses between 1.5 x 10-4 and 10.5 x 10-4 mGy/MBq. The effective dose was estimated at 5.55 x 10-4 mSv/MBq. Human radiation dosimetry can be performed by the mice biodistribution data and important data for clinical safe trial of 123I-Annexin V are provided. (authors)

  14. Absorbed doses received by patients submitted to chest radiographs in hospitals of the city of Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    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 μGy. 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 LAT

  15. Quantification of micronuclei in blood lymphocytes of patients exposed to gamma radiation for dose absorbed assessment

    International Nuclear Information System (INIS)

    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 60Co, 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)

  16. 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)

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

    International Nuclear Information System (INIS)

    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. - Highlights: • A Monte Carlo algorithm to simulate the passage of photons through a homogeneous material was developed. • Two models of a patient's head, one spherical and another more realistic ellipsoidal model, were simulated using the Monte Carlo code. • The fluence into the tumor is different for both head models, but absorbed dose in the tumor is the same

  18. 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.

  19. 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.

  20. 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.

  1. The effect of breast composition on absorbed dose and image contrast

    International Nuclear Information System (INIS)

    We have studied the effect of breast composition on the average whole breast dose, average glandular dose, and image contrast in mammography, using both computational and experimental methods. Three glandular/adipose compositions were considered: 30/70, 50/50, and 70/30 by weight, for both 3- and 5-cm breast thickness. Absorbed dose was found to increase with greater glandular content and this increase is more pronounced for thick breasts and softer beams. For typical screen-film x-ray beams, the average dose to a highly glandular breast is nearly twice the dose to a highly adipose breast and the average glandular dose about 40% higher. Dose was reduced when higher energy beams were employed. The use of a grid increased the dose by a factor of 2.0 to 2.6. Finally, the measured image contrast decreases with increasing breast glandularity, to a greater extent in small breasts and when low energy beams were employed

  2. Absorbed dose to active red bone marrow from diagnostic and therapeutic uses of radiation

    International Nuclear Information System (INIS)

    The bone-marrow dose arising from radiological procedures as carried out in Australia have been determined as part of a survey of population doses. This paper describes the method of calculation of the radiation doses to the active bone marrow from diagnostic radiography, fluoroscopy and radiotherapy. The results of the calculations are compared with the results of other models of bone-marrow dose for a number of diagnostic X-ray procedures

  3. 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).

  4. Comparison of the standards for absorbed dose to water of the NRC and the BIPM for accelerator photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Picard, S.; Burns, D.T.; Roger, P.; Allisy-Roberts, P.J. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); McEwen, M.R.; Cojocaru, C.D.; Ross, C.K. [National Research Council of Canada, Ionizing Radiation Standards, Ottawa, ON (Canada)

    2010-12-15

    A comparison of the dosimetry for high-energy accelerator photon beams was carried out between the National Research Council of Canada (NRC) and the Bureau International des Poids et Mesures (BIPM) in June 2009. The comparison was based on the determination of absorbed dose to water for three radiation qualities. The comparison result, reported as a ratio of the NRC and the BIPM evaluations, is 0.997 at 6 MV, 1.001 at 10 MV and 0.994 at 25 MV, each with a relative standard uncertainty of 6 * 10{sup -3}. This result is the first of the ongoing BIPM.RI(I)-K6 comparison. (authors)

  5. Spectra and absorbed dose by photo-neutrons in a solid water mannequin exposed to a Linac of 15 MV

    International Nuclear Information System (INIS)

    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/cm3. 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)

  6. 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.

  7. Characterization of an absorbed dose standard in water through ionometric methods

    International Nuclear Information System (INIS)

    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, Dagua. 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 Dagua. Finally, since the proposed standard of Dagua 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 Dagua, in Chapter 4 the characteristics of the Picker C/9 unit, the ionization chamber type CC01

  8. 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.

  9. The estimation of absorbed dose rates for non-human biota: an extended intercomparison.

    Science.gov (United States)

    Vives i Batlle, J; 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; Vives Lynch, S; Wood, M D; Yu, C

    2011-05-01

    An exercise to compare 10 approaches for the calculation of unweighted whole-body absorbed dose rates was conducted for 74 radionuclides and five of the ICRP's Reference Animals and Plants, or RAPs (duck, frog, flatfish egg, rat and elongated earthworm), selected for this exercise to cover a range of body sizes, dimensions and exposure scenarios. Results were analysed using a non-parametric method requiring no specific hypotheses about the statistical distribution of data. The obtained unweighted absorbed dose rates for internal exposure compare well between the different approaches, with 70% of the results falling within a range of variation of ±20%. The variation is greater for external exposure, although 90% of the estimates are within an order of magnitude of one another. There are some discernible patterns where specific models over- or under-predicted. These are explained based on the methodological differences including number of daughter products included in the calculation of dose rate for a parent nuclide; source-target geometry; databases for discrete energy and yield of radionuclides; rounding errors in integration algorithms; and intrinsic differences in calculation methods. For certain radionuclides, these factors combine to generate systematic variations between approaches. Overall, the technique chosen to interpret the data enabled methodological differences in dosimetry calculations to be quantified and compared, allowing the identification of common issues between different approaches and providing greater assurance on the fundamental dose conversion coefficient approaches used in available models for assessing radiological effects to biota. PMID:21113609

  10. 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

  11. Evaluation of variation of voltage (kV) absorbed dose in chest CT scans

    International Nuclear Information System (INIS)

    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

  12. The study on quality control for absorbed dose measurement in radiation therapy (II)

    International Nuclear Information System (INIS)

    This study concern the quality system of rod type 7LiF TLD for intercomparison by mail of absorbed doses from 60Co γ-radiation. The system employes 12 7LiF rods in a polystyrene capsule, which are placed at 5 cm depth in water and irradiated to doses to 2.0 Gy. The precision of the readout technique, using 24 capsules and the readout of 12 rods per capsule, is characterized by 1.2% standard error of resulting mean which are less than the EC criteria. By means of two-way TLD postal dose intercomparison with IAEA and IGR, the result of standard deviation are obtained less than 1.0% for each cases

  13. Assessment of absorbed dose to the ovaries of patients undergoing pelvic CT examination

    International Nuclear Information System (INIS)

    Full text of publication follows: Introduction: Although Computed Tomography (CT) procedures constitute about 5% of the total diagnostic radiology procedures but are responsible for about 40% of the total ionizing radiation dose to the general population. As the dose is high especially in the CT of female pelvis, genetic radiation risk is also considerable. Materials and Methods: Radiation doses to the ovaries of the patients undergoing CT examination of the pelvis were measured from 9 different CT scanners available in Isfahan city. For each CT scanner 20 patients were selected. Measurement of organ dose was performed using TLD method. Results and Discussions: Mean and S.D. of absorbed dose to the ovaries from Shimadzo 2500 were 56.6 2.8; from GE Max 640 were 36.8 1.7; from GE Sytec 3000 were 36.6 1.8; from GE Sytec 4000 were 36.6 2.6; from Piker were 38.4 2.1; from Shimadzo 4500 were 36.4 1.2 and from Shimadzo 7800TE 28.2 1.5. Associated risks due to the measured dose are discussed. (author)

  14. 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

  15. Selective fallopian tube catheterisation in female infertility: clinical results and absorbed radiation dose

    International Nuclear Information System (INIS)

    Clinical results of fluoroscopic fallopian tube catheterisation and absorbed radiation doses during the procedure were evaluated in 30 infertility patients with unilateral or bilateral tubal obstruction documented on hysterosalpingography. The staged technique consisted of contrast injection through an intrauterine catheter with a vacuum cup device, ostial salpingography with the wedged catheter, and selective salpingography with a coaxial microcatheter. Of 45 fallopian tubes examined, 35 (78 %) were demonstrated by the procedure, and at least one tube was newly demonstrated in 26 patients (87 %). Six of these patients conceived spontaneously in the follow-up period of 1-11 months. Four pregnancies were intrauterine and 2 were ectopic. This technique provided accurate and detailed information in the diagnosis and treatment of tubal obstruction in infertility patients. The absorbed radiation dose to the ovary in the average standardised procedure was estimated to be 0.9 cGy. Further improvement in the X-ray equipment and technique is required to reduce the radiation dose. (orig.). With 3 figs., 3 tabs

  16. Absorbed and effective dose from spiral and computed tomography for the dental implant planning

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Beong Hee; Han, Won Jeong; Kim, Eun Kyung [Dankook Univ. School of Dentistry, Seoul (Korea, Republic of)

    2001-09-15

    To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. For radiographic projection. TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophages. Effective dose was calculated, using the method suggested by Frederiksen at al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planning.

  17. Absorbed and effective dose from spiral and computed tomography for the dental implant planning

    International Nuclear Information System (INIS)

    To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. For radiographic projection. TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophages. Effective dose was calculated, using the method suggested by Frederiksen at al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planning

  18. 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.

  19. The international protocol for the dosimetry of external radiotherapy beams based on standards of absorbed dose to water

    International Nuclear Information System (INIS)

    An International Code of Practice (CoP, or dosimetry protocol) for external beam radiotherapy dosimetry based on standards of absorbed dose to water has been published by the IAEA on behalf of IAEA, WHO, PAHO and ESTRO. The CoP provides a systematic and internationally unified approach for the determination of the absorbed dose to water in reference conditions with radiotherapy beams. The development of absorbed-dose-to-water standards for high-energy photons and electrons offers the possibility of reducing the uncertainty in the dosimetry of radiotherapy beams. Many laboratories already provide calibrations at the radiation quality of 60Co gamma-rays and some have extended calibrations to high-energy photon and electron beams. The dosimetry of kilovoltage x-rays, as well as that of proton and ion beams can also be based on these standards. Thus, a coherent dosimetry system based on the same formalism is achieved for practically all radiotherapy beams. The practical use of the CoP as simple. The document is formed by a set of different CoPs for each radiation type, which include detailed procedures and worksheets. All CoPs are based on ND,w chamber calibrations at a reference beam quality Qo, together with radiation beam quality correction factors kQ preferably measured directly for the user's chamber in a standards laboratory. Calculated values of kQ are provided together with their uncertainty estimates. Beam quality specifiers are 60Co, TPR20,10 (high-energy photons), R50 (electrons), HVL and kV (x-rays) and Rres (protons and ions)

  20. 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.

  1. Theory, performance, and measured results with an improved absorbed dose water calorimeter. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Domen, S.T.

    1982-01-01

    The feasibility of this calorimeter is mainly the result of the low thermal diffusivity of water that retards a temperature change at a point along a temperature profile. The temperature change is sensed by two calibrated thermistors sandwiched between two polyethylene films that electrically insulate the thermistors from water. The product of the temperature rise and the specific heat of water gives the combined effect of the absorbed dose and any heat defect. Temperature drifts are quickly controlled by making slight changes in electrical power dissipated in the water. Compared to solid-bodied calorimeters requiring vacuum systems, it was easy to construct, to get into operation, and to operate.

  2. Discrimination of various contributions to the absorbed dose in BNCT: Fricke-gel imaging and intercomparison with other experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G. E-mail: grazia.gambarini@mi.infn.it; Agosteo, S.; Marchesi, P.; Nava, E.; Palazzi, P.; Pecci, A.; Rosi, G.; Tinti, R

    2000-11-15

    A method is described for the 3D measurements of absorbed dose in a ferrous sulphate gel phantom, exposed in the thermal column of a nuclear reactor. The method, studied for Boron Neutron Capture Therapy (BNCT) purposes, allows absorbed dose imaging and profiling, with the separation of different contributions coming from different secondary radiations, generated from thermal neutrons. In fact, the biological effectiveness of the different radiations is different. Tests with conventional dosimeters were performed too.

  3. 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.

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Sudha Rana

    2010-01-01

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

  6. CALDoseX: a software tool for absorbed dose calculations in diagnostic radiology

    International Nuclear Information System (INIS)

    Conversion coefficients (CCs) between absorbed dose to organs and tissues at risk and measurable quantities commonly used in X-ray diagnosis have been calculated for the last 30 years mostly with mathematical MIRD5-type phantoms, in which organs are represented by simple geometrical bodies, like ellipsoids, tori, truncated cylinders, etc. In contrast, voxel-based phantoms are true to nature representations of human bodies. The purpose of this study is therefore to calculate CCs for common examinations in X-ray diagnosis with the recently developed MAX06 (Male Adult voXel) and FAX06 (Female Adult voXel) phantoms for various projections and different X-ray spectra and to make these CCs available to the public through a software tool, called CALDoseX (CALculation of Dose for X-ray diagnosis). (author)

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

    Science.gov (United States)

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

    2003-01-01

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

  8. Absorbed dose measurements of mixed pile radiation in aqueous radiation chemistry

    International Nuclear Information System (INIS)

    To use a nuclear reactor as a radiation source in the radiation chemistry of water and aqueous solutions, reliable routine dosimetry techniques are of basic importance. For this purpose we have tried to develop a calorimetric device and a chemical system. The differential calorimeter described here permits simultaneous measurements of energy absorption in different materials. From these values the relative contributions from gammas and non-thermalized neutrons to the total absorbed dose can be calculated. The possibility of inserting a liquid sample into the calorimeter makes it very convenient for radiation chemical studies of aqueous solutions or, generally, liquid systems. For a period of about two years, reliable values for the absorbed doses in different materials have been obtained, which are in good agreement with other physical measurements in the RA research reactor at Vinca. The chemical system described is an aqueous solution of oxalic acid. Its advantages are: the possibility of measurements in the multi-megarad region and negligible induced radioactivity. The results of calorimetric and chemical measurements are presented

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

    Energy Technology Data Exchange (ETDEWEB)

    Garnica-Garza, H M [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional Unidad Monterrey, Via del Conocimiento 201 Parque de Investigacion e Innovacion Tecnologica, Apodaca NL C.P. 66600 (Mexico)], E-mail: hgarnica@cinvestav.mx

    2009-09-21

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

  10. The sensitivity analysis of tooth enamel to the absorbed dose for the application to EPR dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Dae Seok; Lee, Kun Jai [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Cho, Young Hwan [KAERI, Taejon (Korea, Republic of)

    2002-10-01

    Electron Paramagnetic Resonance (EPR) spectroscopy is one of the methods applicable to retrospective dosimetry. The retrospective dosimetry is a process that is a part of dose reconstruction for estimation of exposed dose occurred years before the estimation. Many techniques can be used to the retrospective dosimetry. As a physical method, EPR analysis of biological material measures the quantity of free radicals generated in the material from the interaction of radiation and material. Since the later 80s, in many countries, EPR dosimetry with tooth enamel has been studied and applied for the retrospective dosimetry. In the consideration of the biological materials for EPR dosimetry, human fingernail, hair, bone and tooth are generally considered. The tooth can be separated as enamel, dentine and cementum. Among the three parts, enamel shows the best sensitivity to the absorbed dose and is most widely used. In this study, the characteristics of tooth enamel for EPR dosimetry is examined and experimented. At the experiment, for easy separation, tooth was cut into 4 parts and then each part is treated by ultrasonic vibration in NaOH liquid to reduce mechanically induced noise in the corresponding signal. After the separation of the enamel from dentine, background EPR signal is measured and then radiation-induced EPR spectrum is estimated.

  11. 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)

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

    International Nuclear Information System (INIS)

    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 60Co 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)

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  15. 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)

  16. 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)

  17. Magnetic Resonance Imaging-Based Radiation-Absorbed Dose Estimation of {sup 166}Ho Microspheres in Liver Radioembolization

    Energy Technology Data Exchange (ETDEWEB)

    Seevinck, Peter R., E-mail: p.seevinck@umcutrecht.nl [Image Sciences Institute, University Medical Center Utrecht, Utrecht (Netherlands); Maat, Gerrit H. van de [Image Sciences Institute, University Medical Center Utrecht, Utrecht (Netherlands); Wit, Tim C. de [Department of Nuclear Medicine, Amsterdam Medical Centre, Amsterdam (Netherlands); Vente, Maarten A.D.; Nijsen, Johannes F.W. [Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht (Netherlands); Bakker, Chris J.G. [Image Sciences Institute, University Medical Center Utrecht, Utrecht (Netherlands); Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Utrecht (Netherlands)

    2012-07-01

    Purpose: To investigate the potential of magnetic resonance imaging (MRI) for accurate assessment of the three-dimensional {sup 166}Ho activity distribution to estimate radiation-absorbed dose distributions in {sup 166}Ho-loaded poly (L-lactic acid) microsphere ({sup 166}Ho-PLLA-MS) liver radioembolization. Methods and Materials: MRI, computed tomography (CT), and single photon emission CT (SPECT) experiments were conducted on an anthropomorphic gel phantom with tumor-simulating gel samples and on an excised human tumor-bearing liver, both containing known amounts of {sup 166}Ho-PLLA-MS. Three-dimensional radiation-absorbed dose distributions were estimated at the voxel level by convolving the {sup 166}Ho activity distribution, derived from quantitative MRI data, with a {sup 166}Ho dose point-kernel generated by MCNP (Monte Carlo N-Particle transport code) and from Medical Internal Radiation Dose Pamphlet 17. MRI-based radiation-absorbed dose distributions were qualitatively compared with CT and autoradiography images and quantitatively compared with SPECT-based dose distributions. Both MRI- and SPECT-based activity estimations were validated against dose calibrator measurements. Results: Evaluation on an anthropomorphic phantom showed that MRI enables accurate assessment of local {sup 166}Ho-PLLA-MS mass and activity distributions, as supported by a regression coefficient of 1.05 and a correlation coefficient of 0.99, relating local MRI-based mass and activity calculations to reference values obtained with a dose calibrator. Estimated MRI-based radiation-absorbed dose distributions of {sup 166}Ho-PLLA-MS in an ex vivo human liver visually showed high correspondence to SPECT-based radiation-absorbed dose distributions. Quantitative analysis revealed that the differences in local and total amounts of {sup 166}Ho-PLLA-MS estimated by MRI, SPECT, and the dose calibrator were within 10%. Excellent agreement was observed between MRI- and SPECT-based dose

  18. Secondary neutron dose measurement for proton eye treatment using an eye snout with a borated neutron absorber

    International Nuclear Information System (INIS)

    We measured and assessed ways to reduce the secondary neutron dose from a system for proton eye treatment. Proton beams of 60.30 MeV were delivered through an eye-treatment snout in passive scattering mode. Allyl diglycol carbonate (CR-39) etch detectors were used to measure the neutron dose in the external field at 0.00, 1.64, and 6.00 cm depths in a water phantom. Secondary neutron doses were measured and compared between those with and without a high-hydrogen–boron-containing block. In addition, the neutron energy and vertices distribution were obtained by using a Geant4 Monte Carlo simulation. The ratio of the maximum neutron dose equivalent to the proton absorbed dose (H(10)/D) at 2.00 cm from the beam field edge was 8.79 ± 1.28 mSv/Gy. The ratio of the neutron dose equivalent to the proton absorbed dose with and without a high hydrogen-boron containing block was 0.63 ± 0.06 to 1.15 ± 0.13 mSv/Gy at 2.00 cm from the edge of the field at depths of 0.00, 1.64, and 6.00 cm. We found that the out-of-field secondary neutron dose in proton eye treatment with an eye snout is relatively small, and it can be further reduced by installing a borated neutron absorbing material

  19. Influence of high absorbed irradiation doses on conversion of CO2-H2S mixtures

    International Nuclear Information System (INIS)

    It was investigated the CO2-H2S mixture radiolysis at large absorbed irradiation doses. The observed high yield of final products in this system (Gpr.≥10.0) gives the possibility to consider the radiolytic hydrogen sulphide decomposition as one of the variants of purification of hydrogen sulphide containing residues of natural gas with a simultaneous production of sulphur and synthesis-gas (CO2). It has been show that at dose MGy∼16 % of initial product convert into synthesis-gas and sulfur. The mechanism of radiolytic conversion is discussed and the observed yield of hydrogen made G0(H2)=11.0±0.8 that considerably excesses G0(H2) at radiolysis of pure H2S(G0(H2)=7.5±0.5). Accumulation of carbon monoxide is described with 5 % accuracy with parabola of the second order: [CO] (-0.00082+0.359D-0.0013D2)·1019 mol/cm3 the initial yield of CO production for the given mixture is equal 3.59 which is G0(CO) = 4.5 in recalculation upon pure carbon dioxide. It has been established that the radiolytic reprocessing of acidic components of natural gas (CO2, H2S) gives the possibility to product sulphur and synthesis gas with yield to 30 vol.% (D=10 MGy), and the opportunity of simultaneous decision of ecological problems

  20. Dependence of TLD thermoluminescence yield on absorbed dose in a thermal neutron field.

    Science.gov (United States)

    Gambarini, G; Roy, M S

    1997-01-01

    The emission from 6LiF and 7LiF thermoluminescence dosimeters (TLDs) exposed to the mixed field of thermal neutrons and gamma-rays of the thermal facility of a TRIGA MARK II nuclear reactor has been investigated for various thermal neutron fluences of the order of magnitude of those utilised in radiotherapy, with the purpose of investigating the reliability of TLD readouts in such radiation fields and of giving some information for better obtainment of the absorbed dose values. The emission after exposure in this mixed field is compared with the emission after gamma-rays only. The glow curves have been deconvoluted into gaussian peaks, and the differences in the characteristics of the peaks observed for the two radiation fields, having different linear energy transfers, and for different doses are shown. Irreversible radiation damage in dosimeters having high sensitivity to thermal neutrons is also reported, showing a memory effect of the previous thermal neutron irradiation history which is not restored by anneal treatment. PMID:9463872

  1. Study of natural radionuclide and absorbed gamma dose in Ukhimath area of Garhwal Himalaya, India.

    Science.gov (United States)

    Rautela, B S; Yadav, M; Bourai, A A; Joshi, V; Gusain, G S; Ramola, R C

    2012-11-01

    Natural radiation is the largest contributor to the collective radiation dose of the world population. It is widely distributed in different geological formations such as soil, rocks, air and groundwater. In the present investigation, (226)Ra, (232)Th and (40)K were measured in soil samples of the Ukhimath region of Garhwal Himalaya, India using NaI(Tl) gamma-ray spectrometry. The activity concentrations of naturally occurring radionuclides (226)Ra, (232)Th and (40)K were found to vary from 38.4 ± 6.1 to 141.7 ± 11.9 Bq kg(-1) with an average of 80.5 Bq kg(-1), 57.0 ± 7.5 to 155.9 ± 12.4 Bq kg(-1) with an average of 118.9 Bq kg(-1) and 9.0 ± 3.0 to 672.8 ± 25.9 Bq kg(-1) with an average of 341 Bq kg(-1), respectively. The total absorbed gamma dose rate varies from 70.4 to 169.1 nGy h(-1) with an average of 123.4 nGy h(-1). This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details. PMID:22908360

  2. Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Aghara, S.K. [Prairie View A and M University, Chemical Engineering (Nuclear Program), P.O. Box 519, MS 2505, Prairie View, TX 77446 (United States)], E-mail: Sukesh.K.Aghara@nasa.gov; Blattnig, S.R.; Norbury, J.W.; Singleterry, R.C. [NASA Langley Research Center, Hampton, VA 23681 (United States)

    2009-04-15

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

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

    Science.gov (United States)

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

    2009-01-01

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

  4. Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays

    Science.gov (United States)

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

    2009-04-01

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

  5. Relationship of tumor absorbed doses of 177Lu-DOTA-TATE treatment and uptake in pre-therapeutic Ga68 DOTA-TATE PET/CT imaging

    International Nuclear Information System (INIS)

    Full text of publication follows. Introduction/Background: Peptide Receptor Radionuclide Therapy (PRRT) with labeled Lu177 labeled peptide in patients with neuroendocrine tumors (NETs) aroused great interest. An estimation of actual radiation doses to tumors is very important for therapy planning. It is well known that uptake of Ga-68 DOTATATE very well correlated with sst2 expression. The uptake of radio-labelled peptides calculated from SUV max values may predict the radiation-absorbed dosimetry of lesions treated with PRRT. Aim: the aim of the study was to evaluate the relationship between the tumor absorbed doses and pre-therapeutic Ga68 DOTA-TATE PET/CT uptake calculated from SUV values. Materials and methods: PRRT results of patients (M/F: 8/5, mean age: 55.5 ± 12.5 years) with histologically proven inoperable NETs were retrospectively analyzed. Dosimetric calculations were performed using MIRD scheme and lesion doses were calculated using post therapy whole body images obtained at 4, 20, 44, and 68 hours after injection. Calculated tumor absorbed doses were compared with SUVmax of 68Ga-DOTA-TATE PET/CT, which were performed before the therapy. Tumor volumes were determined from CT images. Thirteen blood samples beginning from time zero to 4 days after injection were obtained for bone marrow and whole body dosimetry. Results: there were 38 lesions in 13 patients. Lesions were selected according to lesion delineation and superimposed lesions were excluded. Mean lesion volume was 19.58 ± 25 cm3. Median tumor dose for all lesions, bone lesions, lesions on other sites (lung, liver, lymph nodes) were 15.08 Gy, 19.34 Gy, 14.05 Gy per 370 MBq respectively. Median SUVmax values of those were 25.8, 13.7, 23.05, respectively. Correlation between calculated tumor dose and uptake of 68Ga-DOTA-TATE was moderate (R=0.42). Also a moderate correlation was found for radiation absorbed doses of bone metastases. A very low correlation was found for radiation absorbed doses of

  6. 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.

  7. Calorimetry for absorbed dose measurement at 1-4 MeV electron accelerators

    International Nuclear Information System (INIS)

    Calorimeters are used for dose measurement, calibration and intercomparisons at industrial electron accelerators, and their use at 10 MeV electron accelerators is well documented. The work under this research agreement concerns development of calorimeters for use at electron accelerators with energies in the range of 2-4 MeV. The dose range of the calorimeters is 3-40 kGy, and their temperature stability after irradiation was found to be sufficient for practical use in an industrial environment. Measurement uncertainties were determined to be 5% at k = 2. (author)

  8. Variations in absorbed doses from 51Cr in investigations with labelled erythrocytes

    International Nuclear Information System (INIS)

    In nuclear medicine 51Cr labelled red blood cells are used to determine erythrocyte volume, red cell survival, or the site of red cell destruction. The author examined the variations in adsorbed doses from 51Cr in 77 patients with various diseases in whom erythrokinetic investigations were performed for diagnostic purposes. Autologous erythrocytes were incubated with Na2CrO4 (37 kBq (1.0 uCi) 51Cr/kg body weight) and injected intravenously. 51Cr activity in blood was then followed for 10 weeks. 51Cr activity over liver, spleen, and sacrum and whole-body retention of 51Cr were measured for the same period. A compartmental model was assumed to describe the kinetics of 51Cr tagged to red blood cells. It is a noncirculating linear model with the compartments represented by organs (spleen, liver, bone, residual body) rather than physiological compartments. The computer program SAAM-25 was used to provide the kinetic parameters and the organ retention functions. From the cumulated activities of the source regions, organ doses and effective dose equivalents were calculated according to the MIRD concepts. The highest organ doses were found for spleen, liver, and red marrow. The calculated dose values for 51Cr found in this study confirm only partly the values reported in ICRP Publication 17, but are higher up to a factor of 9 for some organs. 16 references, 1 figure, 3 tables

  9. The provision of national standards of absorbed dose for radiation processing. The role of NPL in the United Kingdom

    International Nuclear Information System (INIS)

    The system of national and international standardization is examined, particularly with respect to the problems of standardizing high absorbed dose measurements required in processing with photons from cobalt-60 and electrons. The need for development of primary standards specifically dedicated to this application versus the possibility of extrapolation from standards in use at lower dose levels is considered together with means for dissemination and intercomparison. The present status of standards at NPL and the future programme are outlined. (author)

  10. 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

  11. Absolute dose determinations in electron beams - Intercomparison of methodologies

    International Nuclear Information System (INIS)

    The use of plane parallel ionization chambers for the dosimetry of electron beams has been extensively recognized in national and international recommendations and codes of practice. The construction details of different chambers and their influence on the measure, which should be converted in suitable perturbation factors, have also been published. Updated information, new data, refined investigations have recently been gathered in IAEA TRS 398 where the major efforts of Primary Standard Dosimetry Laboratories (PSDLs) in providing calibration factors in terms of absorbed dose to water at a reference quality is reflected. From the users point of view, and specially concerning electron beams, one can probably get confused with different methodologies and procedures in order to accurately determine absorbed dose to water. The aim of this work is to explore the different methodologies and procedures concerning absolute dose determinations, in a hospital and using different chambers, in order to appreciate the relative deviations in absolute dose values. Despite the fact that Markus chamber does not meet all the minimum requirements namely concerning scattering perturbation effects due to the geometry and dimensions of the guard electrode, it is still a quite used chamber type in current clinical practice. So we have included dose determinations with this plane parallel chamber (PTW 23343) and also with a Roos chamber (PTW 34001). Markus chamber is provided with a standard calibration certificate in terms of absorbed dose to water (NW) and also in terms of absorbed dose to air (NA), referred to a high energy electron beam whereas Roos chamber has a calibration factor in terms of absorbed dose to water referred to 60Co. Starting from these materials different methodologies have been applied: i) Using NA of Markus chamber according to the users instruction manual which refers DGMP Report No.6 Praktische Dosimetrie von Elektronenstrahlung und ultraharter Rontgenstrahlung

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

    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 0.3401 and 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 3 months. 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. (authors)

  15. Simulation of absorbed dose rate due to synchrotron radiation and shielding thickness for radiation safety at Indus-2 using FLUKA

    International Nuclear Information System (INIS)

    Indus-2 is a 2.5 GeV electron synchrotron radiation source at Raja Ramanna Centre for Advanced Technology (RRCAT), India. 26 synchrotron radiation (SR) beam lines are planned in Indus-2 for various research applications, of several are in operation and many are in installation stage. For experiments SR beam is brought in air. Due to intense flux of SR and low energy, the dose rate in the direct beam is high and there is a potential for radiation exposure. Appropriate shielding hutches are needed to house the beamlines and protect the workers from the radiation hazard. Simulations were carried out using computer code FLUKA to find out the absorbed dose in water due to SR and required shielding thickness in the forward direction to reduce dose within acceptable limits. SR spectrum from Indus-2 in the range 4-100 keV was used for simulating the absorbed dose and shielding thickness. It was found that the absorbed dose rate is of the order of 105 Gy/h for the design parameters of Indus-2 (2.5 GeV and 300 mA). Forward shielding thickness of 3 mm lead was found to be sufficient to reduce the dose rate to acceptable level for continuously occupied area (<1μSv/h). The details of the simulation and results are presented in the paper. (author)

  16. ESR Evaluation of stable free radicals produced by ionizing radiation in multifunctional substances. Application for absorbed dose measurements in radiotherapy

    International Nuclear Information System (INIS)

    Electron Spin Resonance dosimetry is a useful system for measuring absorbed dose in radiotherapy. This work describes the results obtained at the University of Palermo regarding an experimental study aimed to optimize the properties of alanine based dosimeters and to analyze other materials, that could be alternatives to alanine

  17. 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)

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

    Science.gov (United States)

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

    2010-03-01

    The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry. PMID:19889800

  19. Absorbed dose distributions in patients with bone metastases from hormone refractory prostate cancer treated with Re-186 HEDP

    International Nuclear Information System (INIS)

    Full text of publication follows. Aim: intravenous administration of Re-186 hydroxyethylidene-diphosphonate (HEDP) is used for metastatic bone pain palliation in hormone refractory prostate cancer patients. Dosimetry for bone seeking radionuclides is challenging due to the complex structure with osteoblastic, osteolytic and mixed lesions. The aim of this study was to perform image-based patient-specific 3D convolution dosimetry to obtain a distribution of the absorbed doses to each lesion and estimate inter- and intra-patient variations. Materials and methods: 28 patients received a fixed 5 GBq activity of Re-186 HEDP followed by peripheral blood stem cell rescue at 14 days in a phase II trial. A FORTE dual-headed gamma camera was used to acquire sequential Single-Photon-Emission Computed Tomography (SPECT) data of the thorax and pelvis area at 1, 4, 24, 48 and 72 hours following administration. The projection data were reconstructed using filtered-back projection and were corrected for attenuation and scatter. Voxelised cumulated activity distributions were obtained with two different methods. First, the scans were co-registered and the time-activity curves were obtained on a voxel-by-voxel basis. Second, the clearance curve was obtained from the mean number of counts in each individual lesion and used to scale the uptake distribution taken at 24 hours. The calibration factors required for image quantification were obtained from a phantom experiment. An in-house developed EGSnrc Monte Carlo code was used for the calculation of dose voxel kernels for soft-tissue and cortical/trabecular bone used to perform convolution dosimetry. Cumulative dose-volume histograms were produced and mean absorbed doses calculated for each spinal and pelvic lesion. Results: preliminary results show that the lesion mean absorbed doses ranged from 25 to 55 Gy when the medium was soft tissue and decreased by 40% if bone was considered. The use of the cumulated activity distribution

  20. Determinants of thiopental induction dose requirements.

    Science.gov (United States)

    Avram, M J; Sanghvi, R; Henthorn, T K; Krejcie, T C; Shanks, C A; Fragen, R J; Howard, K A; Kaczynski, D A

    1993-01-01

    Dose requirements for thiopental anesthetic induction have significant age- and gender-related variability. We studied the association of the patient characteristics age, gender, weight, lean body mass, and cardiac output with thiopental requirements. Doses of thiopental, infused at 150 mg/min, required to reach both a clinical end-point and an electroencephalographic (EEG) end-point were determined in 30 males and 30 females, aged 18-83 yr. Univariate least squares linear regression analysis revealed outliers in the relationships of age, weight, lean body mass, and cardiac output to thiopental dose at clinical and EEG endpoints. Differential weighting of data points minimized the effect of outliers in the construction of a robust multiple linear regression model of the relationship between several selected independent variables and the dependent variables thiopental dose at clinical and EEG endpoints. The multiple linear regression model for thiopental dose at the clinical end-point selecting the regressor variables age, weight, and gender (R2 = 0.76) was similar to that for age, lean body mass, and gender (R2 = 0.75). Thiopental dose at the EEG endpoint was better described by models selecting the variables age, weight, and cardiac output (R2 = 0.88) or age, lean body mass, and cardiac output (R2 = 0.87). Although cardiac output varied with age, age always remained a selected variable. Because weight and lean body mass differed with gender, their selection as variables in the model eliminated gender as a selected variable or minimized its importance.

  1. Determinants of thiopental induction dose requirements.

    Science.gov (United States)

    Avram, M J; Sanghvi, R; Henthorn, T K; Krejcie, T C; Shanks, C A; Fragen, R J; Howard, K A; Kaczynski, D A

    1993-01-01

    Dose requirements for thiopental anesthetic induction have significant age- and gender-related variability. We studied the association of the patient characteristics age, gender, weight, lean body mass, and cardiac output with thiopental requirements. Doses of thiopental, infused at 150 mg/min, required to reach both a clinical end-point and an electroencephalographic (EEG) end-point were determined in 30 males and 30 females, aged 18-83 yr. Univariate least squares linear regression analysis revealed outliers in the relationships of age, weight, lean body mass, and cardiac output to thiopental dose at clinical and EEG endpoints. Differential weighting of data points minimized the effect of outliers in the construction of a robust multiple linear regression model of the relationship between several selected independent variables and the dependent variables thiopental dose at clinical and EEG endpoints. The multiple linear regression model for thiopental dose at the clinical end-point selecting the regressor variables age, weight, and gender (R2 = 0.76) was similar to that for age, lean body mass, and gender (R2 = 0.75). Thiopental dose at the EEG endpoint was better described by models selecting the variables age, weight, and cardiac output (R2 = 0.88) or age, lean body mass, and cardiac output (R2 = 0.87). Although cardiac output varied with age, age always remained a selected variable. Because weight and lean body mass differed with gender, their selection as variables in the model eliminated gender as a selected variable or minimized its importance. PMID:8418708

  2. Determination of Entrance Skin Doses and Organ Doses for Medical X Ray Examinations

    International Nuclear Information System (INIS)

    A national survey of patient doses for diagnostic X ray radiographs is planned in Taiwan. Entrance skin doses and organ doses for all installed X ray machines will be investigated. A pilot study has been carried out for the national survey to develop a protocol for the dose assessment. Entrance skin doses and organ doses were measured by thermoluminescence dosemeters and calculated by Monte Carlo simulations for several X ray examinations. The conversion factor from free air entrance absorbed dose to entrance skin dose was derived. A formula for the computation of entrance skin doses from inputs of kVp, mA.s, source to skin distance, aluminium filtration, and generator rectifying was constructed. Organ doses were measured using a RANDO phantom and calculated using a mathematical phantom. All data will be passed to the Atomic Energy Council for developing a programme of national survey and regulatory controls for diagnostic X ray examinations. (author)

  3. Risk- and cost-benefit analyses of breast screening programs derived from absorbed dose measurements in the Netherlands

    International Nuclear Information System (INIS)

    Risk- and cost benefit analyses for breast screening programs are being performed, employing the risk-factors for induction of breast cancer from six extensive follow-up studies. For women of the age group above 35 years and for a risk period of 30 years after a 10-year latency period, a factor of extra cases of 20 x 10-6 mGy-1 can be estimated. Measurements are being performed in Dutch hospitals to determine the mean absorbed tissue dose. These doses vary from 0.6 to 4.4 mGy per radiography. For a dose of 1 mGy per radiograph and yearly screening of women between 35 and 75 years, the risk of radiogenic breast cancer is about 1% of the natural incidence (85,000 per 106 women) in this group. A recommended frequency of screening has to be based on medical, social and financial considerations. The gain in woman years and in completely cured women is being estimated for screening with intervals of 12 instead of 24 months. The medical and social benefit is 1,520 years life-time and 69 more cases completely cured per 1,000 breast cancer patients. The financial profit of a completely cured instead of an ultimately fatal cancer can be roughly estimated at 55,000 guilders. In addition the costs per gained woman-year are about 5,000 guilders. In consequence, the extra costs of annual additional rounds of mammographic screening are balanced by the benefit. (Auth.)

  4. 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)

  5. 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.

  6. Estimation of kidney depth effective renal plasmatic flux and absorbed dose, from a radio isotopic renogram

    International Nuclear Information System (INIS)

    A technique for the estimation of kidney depth is described. It is based on a comparison between the measurements obtained in a radioisotopic renogram carried out for two specific energies and the same measurements made with a phanto-kidney at different depths. Experiments performed with kidney and abdomen phantoms provide calibration curves which are obtained by plotting the photopeak to scatter ratio for 131I pulse height spectrum against depth. Through this technique it is possible to obtain the Hippuran-131I kidney uptake with external measurements only. In fact it introduces a correction in the measurements for the depth itself and for the attenuation and scattering effects due to the tissues interposed between the kidney and the detector. When the two kidneys are not equidistant from the detector, their respective renograms are different and it is therefore very important to introduce a correction to the measurements according to the organ depth in order to obtain the exact information on Hippuran partition between the kidneys. The significative influence of the extrarenal activity is analyzed in the renogram by monitoring the praecordial region after 131I-human serum albumin injection and establishing a calibration factor relating the radioactivity level of this area to that present in each kidney area. It is shown that it is possible to obtain the values for the clearance of each kidney from the renogram once the alteration in efficiency due to the organ depth and to non-renal tissue interference in the renal area is considered. This way, values for the effective renal plasma flow were obtained, which are comparable to those obtained with other techniques, estimating the total flow of the kidneys. Finally the mean absorbed dose of the kidneys in a renography is also estimated. (Author)

  7. DOSE-Analyzer. A computer program with graphical user interface to analyze absorbed dose inside a body of mouse and human upon external neutron exposure

    International Nuclear Information System (INIS)

    DOSE-Analyzer is a computer program to retrieve the dose information from a database and generate a graph through a graphical user interface (GUI). The database is constructed for absorbed dose, fluence, and energy distribution inside a body of mouse and human exposed upon external neutrons, which is calculated by our developed Monte-Carlo simulation method using voxel-based phantom and particle transport code PHITS. The input configurations of irradiation geometry, subject, and energy are set by GUI. The results are tabulated at particle types, i.e. electron, proton, deuteron, triton, and alpha particle, and target organs on a data sheet of Microsoft Office ExcelTM. Simple analysis to compare the output values for two subjects is also performed on DOSE-Analyzer. This report is a user manual of DOSE-Analyzer. (author)

  8. 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

  9. Determination of the dose index in computerized tomography using thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    In this work the obtained results of the determination of the dose index are presented in thorax studies in computed tomography and helical tomography carried out in Mexico using thermoluminescent dosemeters of LiF: Mg,Cu,P + Ptfe developed and manufactured in our country. The results showed that under similar conditions of irradiation and operation (pitch = 1), significant differences don't exist among the doses absorbed measures in the phantom due to the two types of used tomographs. (Author)

  10. 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

    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 by the B......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...... 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 102. Evidence of a dose...

  11. Glucocorticoid dose determines osteocyte cell fate

    OpenAIRE

    Jia, Junjing; Yao, Wei; Guan, Min; Dai, WeiWei; Shahnazari, Mohammad; Kar, Rekha; Bonewald, Lynda; Jiang, Jean X.; Lane, Nancy E.

    2011-01-01

    In response to cellular insult, several pathways can be activated, including necrosis, apoptosis, and autophagy. Because glucocorticoids (GCs) have been shown to induce both osteocyte apoptosis and autophagy, we sought to determine whether osteocyte cell fate in the presence of GCs was dose dependent by performing in vivo and in vitro studies. Male Swiss-Webster mice were treated with slow-release prednisolone pellets at 1.4, 2.8, and 5.6 mg/kg/d for 28 d. An osteocyte cell line, MLO-Y4 cells...

  12. 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)

  13. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation; Comparacao da dose absorvida no tratamento do cancer ginecologico por braquiterapia de alta taxa de dose utilizando o planejamento convencional do tratamento e simulacao de Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Aneli Oliveira da

    2010-07-01

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of {sup 192}Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results

  14. 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

  15. Measurement of patient skin absorbed dose in ablation of paroxysmal atrial fibrillation, and examination of treatment protocol

    International Nuclear Information System (INIS)

    The ablation for atrial fibrillation minute movement done in our hospital is 250 minutes or less, within an average time of 150 minutes during a fluoroscopic time of about 7 hours, with very large average inspection times numerical values. However, the skin-absorbed dose could be understood only from the numerical value of the area dosimeter. It was considered that the total dose that reached the threshold was sufficient, although radiation injury would not be reported from the ablation currently done at our hospital. Therefore, we aimed to examine the inspection protocol in this hospital, and to request the patient be given an inspection dose that was the average skin-absorbed dose by using the acryl board. The amount of a total dose for an inspection of 150 minutes of fluoroscopic time was about 2.7 Gy. Moreover, a value of 1.5 Gy was indicated in the hot spot as a result of repetition in some exposure fields. However, it was thought that the possibility of exceeding the threshold of 2 Gy depending on the inspection situation in the future and other factors was tolerable because these measurements were done so as not to overvalue it more than the necessary. (author)

  16. The Effects on Absorbed Dose Distribution in Intraoral X-ray Imaging When Using Tube Voltages of 60 and 70 kV for Bitewing Imaging

    OpenAIRE

    Kristina Hellén-Halme; Mats Nilsson

    2013-01-01

    ABSTRACT Objectives Efforts are made in radiographic examinations to obtain the best image quality with the lowest possible absorbed dose to the patient. In dental radiography, the absorbed dose to patients is very low, but exposures are relatively frequent. It has been suggested that frequent low-dose exposures can pose a risk for development of future cancer. It has previously been reported that there was no significant difference in the diagnostic accuracy of approximal carious lesions in ...

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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 uncertainities are within reported values. (author)

  19. 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.

  20. Glass Detectors for Dose Determination in a Flower Irradiation Process

    Energy Technology Data Exchange (ETDEWEB)

    Quezada, V.A.C.; Caldas, L.V.E. [Sao Paulo (Brazil)

    1999-07-01

    A routine dosimetric system was developed using commercial glass samples. Using the optical absorption technique, the dosimetric characteristics of Brazilian glass samples, batch uniformity, response reproducibility, re-use, absorbed dose response, detection range, response stability, were studied. As an application, the dosimetric system was tested in a flower irradiation process. All the obtained results show the usefulness of the proposed system for high dose dosimetry. (author)

  1. 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.

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  5. 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.

  6. Comparison between Radiology Science Laboratory, Brazil (LCR) and National Research Council, Canada (NRC) of the absorbed dose in water using Fricke dosimetry

    International Nuclear Information System (INIS)

    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)

  7. 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.

  8. Estimated fluence-to-absorbed dose conversion coefficients for use in radiological protection of embryo and foetus against external exposure to photons from 50 keV to 10 GeV

    International Nuclear Information System (INIS)

    In the literature, no conversion coefficients are available for use in radiological protection of the embryo and foetus against external exposure to photons. This study used the Monte-Carlo code MCNPX to determine mean absorbed doses to the embryo and foetus when the mother is exposed to external photon fields. Monoenergetic photons ranging from 50 keV to 10 GeV were considered. The irradiation geometries included antero-posterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT), and isotropic (ISO). At each of these standard irradiation geometries, absorbed doses to the foetal brain and body were calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months. Photon fluence-to-absorbed-dose conversion coefficients were estimated for the four prenatal ages. (authors)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Supanich, M [Rush University Medical Center, Chicago, IL (United States); Siegelman, J [Brigham and Women' s Hospital Harvard Medical School, Boston, MA (United States)

    2014-06-15

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

  11. 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

  12. Measurement and modeling of gamma-absorbed doses due to atmospheric releases from Los Alamos Meson Physics Facility

    International Nuclear Information System (INIS)

    Short-term gamma-absorbed doses were measured by one high-pressure ionization chamber (HPIC) at an azimuth of 120 from the Los Alamos Meson Physics Facility (LAMPF) stack during the January 1 through February 8 operating cycle. Two HPICs were in the field during the September 8 through December 31 operating cycle, one north and the other north-northeast of the LAMPF stack, but they did not provide reliable data. Meteorological data were also measured at both East Gate and LAMPF. Airborne emission data were taken at the stack. Daily model predictions, based on the integration of modeled 15-min periods, were made for the first LAMPF operating cycle and were compared with the measured data. A comparison of the predicted and measured daily gamma doses due to LAMPF emissions is presented. There is very good correlation between measured and predicted values. During 39-day operating cycles, the model predicted an absorbed dose of 10.3 mrad compared with the 8.8 mrad that was measured, an overprediction of 17%

  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

    , intraperitoneal (i.p.) targeted α therapy has been proposed as an adjuvant treatment for minimal residual disease after successful primary treatment. In the present study, we calculated absorbed and relative biological effect (RBE)-weighted (equivalent) doses in relevant normal tissues and estimated the effective...... of the infused therapy solution. RESULTS: The urinary bladder, thyroid, and kidneys (1.9, 1.8, and 1.7 mGy per MBq/L) received the 3 highest estimated absorbed doses. When the tissue-weighting factors were applied, the largest contributors to the effective dose were the lungs, stomach, and urinary bladder. Using...... 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. 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%.

  15. 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

  16. 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)

  17. 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

  18. 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.

  19. Hormone regulation system and cyclic nucleotids in the Chernobyl accident liquidators with doses absorbed less then 1 Gy

    International Nuclear Information System (INIS)

    During 6 years after the accident (1987-1992) a functional state of endocrine system that regulate the adaptation, reproduction, metabolism, vessels tonicity and water-electrolyte balance were investigated in 249 liquidators with doses absorbed less then 1 Gy. The changes of these systems activity in state of basal secretion and peculiarities of their reactions under influence of perturbation (adrenaline, insulin) were revealed. Post-irradiation endocrinopathy was characterized and its role in decrease of the organism's adaptation and in mechanism of sanogenesis and pathogenesis was found. (author)

  20. 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)

  1. Evaluation of absorbed dose in studies of renal function due to 123I/131I (hippuran) e 111In (DPTA)

    International Nuclear Information System (INIS)

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

  2. 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

  3. 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

    2013-05-01

    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.

  4. Thyroid dose of I-131 absorbed by the internal organs of a pregnant woman

    International Nuclear Information System (INIS)

    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)

  5. Determining organ dose: the holy grail

    Energy Technology Data Exchange (ETDEWEB)

    Samei, Ehsan; Tian, Xiaoyu; Segars, W.P. [Duke University, Carl E. Ravin Advanced Imaging Laboratories, Departments of Radiology, Biomedical Engineering, Physics, and Electrical Engineering, Durham, NC (United States)

    2014-10-15

    Among the various metrics to quantify CT radiation dose, organ dose is generally regarded as one of the best to reflect patient radiation burden. Organ dose is dependent on two main factors, namely patient anatomy and irradiation field. An accurate estimation of organ dose requires detailed modeling of both factors. The modeling of patient anatomy needs to reflect the anatomical diversity and complexity across the population so that the attributes of a given clinical patient can be properly accounted for. The modeling of the irradiation field needs to accurately reflect the CT system condition, especially the tube current modulation (TCM) technique. We present an atlas-based method to model patient anatomy via a library of computational phantoms with representative ages, sizes and genders. A clinical patient is matched with a corresponding computational phantom to obtain a representation of patient anatomy. The irradiation field of the CT system is modeled using a validated Monte Carlo simulation program. The tube current modulation profiles are simulated using a manufacturer-generalizable ray-tracing algorithm. Combining the patient model, Monte Carlo results, and TCM profile, organ doses are obtained by multiplying organ dose values from a fixed mA scan (normalized to CTDI{sub vol}-normalized, denoted as h{sub organ}) and an adjustment factor that reflects the specific irradiation of each organ. The accuracy of the proposed method was quantified by simulating clinical abdominopelvic examinations of 58 patients. The predicted organ doses showed good agreement with simulated organ dose across all organs and modulation schemes. For an average CTDI{sub vol} of a CT exam of 10 mGy, the absolute median error across all organs was 0.64 mGy (-0.21 and 0.97 for 25th and 75th percentiles, respectively). The percentage differences were within 15%. The study demonstrates that it is feasible to estimate organ doses in clinical CT examinations for protocols without and with

  6. 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.

  7. TLD estimation of absorbed dose for 131I on the surface of biological organs of REMCAL phantom

    International Nuclear Information System (INIS)

    In nuclear medicine, the accuracy of absorbed dose of an internally distributed radiopharmaceuticals estimated by the MIRD (medical internal radiation dose) method depends on the cumulated activity of the source organs and their mass. The usual method for obtaining the cumulated activities are: 1) direct measurements by a) positron emission tomography (PET) and b) single photon emission computed tomography (SPECT) 2) extrapolation from animal data and 3) calculations based on the mathematical biokinetic model. Among these methods, extrapolation of animal data to humans includes inevitable inaccuracy due to large interspecies metabolic differences with regard to the administered radiochemical. Biokinetic modeling requires adequate knowledge of various kinetic parameters, which is based on some biological assumptions. Direct measurements can provide cumulated distributions with fewer biological assumptions. But direct measurements of PET/SPECT are difficult to perform routinely. A method has been developed to obtain the surface dose of different biological organs by using TLDs. Here, a number of TLDs are placed just above the surface of the biological organs of the REMCAL Alderson human phantom filled with water. Firstly, investigation of the accuracy of this method by calibration studies using the said phantom, which is having the entire biological organ intact and simulate the organs as human body is done. These organs are filled with the known activity of the radioisotope. In the present study, estimation of radiation dose received by fifteen different target organs, when the known activity was filled in the three major organs of interest was carried out

  8. The Effects on Absorbed Dose Distribution in Intraoral X-ray Imaging When Using Tube Voltages of 60 and 70 kV for Bitewing Imaging

    Directory of Open Access Journals (Sweden)

    Kristina Hellén-Halme

    2013-10-01

    Full Text Available Objectives: Efforts are made in radiographic examinations to obtain the best image quality with the lowest possible absorbed dose to the patient. In dental radiography, the absorbed dose to patients is very low, but exposures are relatively frequent. It has been suggested that frequent low-dose exposures can pose a risk for development of future cancer. It has previously been reported that there was no significant difference in the diagnostic accuracy of approximal carious lesions in radiographs obtained using tube voltages of 60 and 70 kV. The aim of this study was, therefore, to evaluate the patient dose resulting from exposures at these tube voltages to obtain intraoral bitewing radiographs.Material and Methods: The absorbed dose distributions resulting from two bitewing exposures were measured at tube voltages of 60 and 70 kV using Gafchromic® film and an anatomical head phantom. The dose was measured in the occlusal plane, and ± 50 mm cranially and caudally to evaluate the amount of scattered radiation. The same entrance dose to the phantom was used. The absorbed dose was expressed as the ratio of the maximal doses, the mean doses and the integral doses at tube voltages of 70 and 60 kV.Results: The patient receives approximately 40 - 50% higher (mean and integral absorbed dose when a tube voltage of 70 kV is used.Conclusions: The results of this study clearly indicate that 60 kV should be used for dental intraoral radiographic examinations for approximal caries detection.

  9. Determination of the conversion coefficient for ambient dose equivalent, H(10), from air kerma measurements

    International Nuclear Information System (INIS)

    Namely the operational magnitudes can be determined by the product of a conversion coefficient by exposure air kerma or fluence, etc. In particular in Mexico for the first time is determined the conversion coefficient (Cc) for operational magnitude Environmental Dose Equivalent H(10) by thermoluminescence dosimetry (TLD) technique. First 30 TLD-100 dosimeters are calibrated in terms of air kerma, then these dosimeters are irradiated inside a sphere ICRU type of PMMA and with the aid of theory cavity the absorbed dose in PMMA is determined at a depth of 10 mm within the sphere DPMMA(10), subsequently absorbed dose to ICRU tissue is corrected and the dose equivalent H(10) is determined. The Cc is determined as the ratio of H(10)/Ka obtaining a value of 1.20 Sv Gy-1 with a uc= 3.66%, this being consistent with the published value in ISO-4037-3 of 1.20 Sv Gy-1 with a uc= 2%. (Author)

  10. 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

  11. 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)

  12. 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.

  13. 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) s...

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

    International Nuclear Information System (INIS)

    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 90Y and 90Sr, 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

  15. Study of the heterogeneity effects of lung in the evaluation of absorbed dose in radiotherapy

    International Nuclear Information System (INIS)

    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 EclipseR 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 EclipseR 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 cm2 treatment field is considered. These differences can cause a considerable subdosage in the lung tissue, reducing the possibility of the patient cure. (author)

  16. 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...

  17. Measurement of absorbed doses near metal and dental material interfaces irradiated by x- and gamma-ray therapy beams

    International Nuclear Information System (INIS)

    Soft-tissue damage adjacent to dental restorations is a deleterious side effect of radiation therapy associated with low-energy electron scatter from dental materials of high electron density. This study was designed to investigate the enhancement of dose to soft tissue (or water) close to high electron-density materials and to measure the detailed lateral and depth-dose profiles in soft-tissue-simulating polymer adjacent to planar interfaces of several higher atomic-number materials: 18-carat gold dental casting alloy; Ag-Hg dental amalgam alloy; Ni-Cr dental casting alloy; and natural human tooth structure. Results indicate that the dose-enhancement in 'tissue' is as great as a factor of 2 on the backscatter side adjacent to gold and a factor of 1.2 adjacent to tooth tissue, but is insignificant on the forward-scatter side because of the predominant effect of attenuation by the high-density, high atomic-number absorbing material. (author)

  18. Physical methods for dose determinations in mammography

    International Nuclear Information System (INIS)

    There is small but significant risk of radiation induced carcinogenesis associated with mammography. High quality mammography is the best method of early breast cancer detection. Besides, image as a basic requirement for an effective diagnosis, radiation protection principles require the radiation dose to the imaged tissue to be as low as compatible with required image quality. Glandular tissues is the most radiosensitive, thus the evaluation of Mean Glandular Dose (MGD) is the most relevant factor for estimation of radiation risk as well as the comparison of performance at different mammographic machines. MGD was estimated using Entrance Surface Air KERMA at the breast surface Kf measured free in air and appropriate conversation factors. Under evaluation were eight mammographic machines at institute of radiology, Skopje and mammographic machines at the Health's centers in Vevchani, Bitola, Prilep, Negotino and Shtip. Estimated values of MGD do not exceed the European reference level (<2mGy), but it can not be generally concluded for all mammography units in Macedonia, until their examination. In the near future all mammography units will be subject of Q C tests and dose measurements. (Author)

  19. The distribution of absorbed dose from x-rays as a function of depth

    Science.gov (United States)

    Cummings, Frederick

    2000-08-01

    Organizations responsible for monitoring the occupational exposure to radiation workers in the U.S. are directed to measure the dose to specific depths in tissue. The knowledge of the depth distribution of energy deposited by radiation in materials is essential to the interpretation of devices used to measure occupational exposure In this work, the quantities used to convert the reference transfer quantity for x-ray fields, air kerma, to the regulatory quantity, dose equivalent, for mono- energetic x-ray fields and poly-energetic x-ray fields specified by the National Institute of Standards and Technology are cogenerated for European x-ray fields are indicated and consistent conversion factors for use in the U.S. are recommended. For the mono-energetic x-ray beams conversion factors ranged from 0.9 to 1.7 at the 7 mg/cm2 depth and from 0.03 to 1.9 at the 1000 mg/cm2 depth in tissue specified by the International Commission of Radiation Units and Measurements. The conversion factors for the NIST x-ray fields were reasonably consistent with values in an unpublished draft standard by the American National Standards Institute, but exhibited sufficient disagreement to warrant a re-evaluation of the factors in that document prior to publication.

  20. Human absorbed dose calculations for 123I labeled phenyl pentadecanoic acid

    International Nuclear Information System (INIS)

    I-123 labeled fatty acids have been proposed for studying myocardial metabolism by scintigraphic methods. With the availability of clean I-123 and the advent of single photon emission tomography, I-123 labeled fatty acids would be well suited to study regional myocardial viability or metabolism in humans. The authors have studied I-125 and I-123 labeled iodophenyl pentadecanoic acid (IPPA) in rats and dogs. Clinical studies are in progress with I-123 (IPPA). They have studied the pharmacokinetics of this tracer in male Sprague-Dawley rats at 0.25, 0.5, 1, 3, 6, and 24 hours postinjection. The cumulated doses, due to both pure I-123 and a version contaminated with 1.4% I-125, in various organs and the total body in humans are estimated. The average dose to organs for humans injected with I-123 IPPA with pure I-123 and contaminated I-123 respectively, are (rads to organ per mCi injected): heart wall (0.0507, 0.0514), liver (0.0792, 0.0875), kidneys (0.0479, 0.0561), thyroid (0.0517, 0.0638), ovaries (0.0427, 0.0561), testes (0.0307, 0.0309), total body (0.0386, 0.0392). 12 references, 9 figures, 5 tables

  1. 131 iodine gamma dose determination in the thyroid gland using two geometrical shapes: a comparative study

    Science.gov (United States)

    Betka, A.; Bentabet, A.; Azbouche, A.; Fenineche, N.; Adjiri, A.; Dib, A.

    2015-05-01

    In order to study the internal gamma dose, we used a Monte Carlo code ‘Penelope’ simulation with two geometrical models (cylindrical and spherical). The deposited energy was determined via the loss of energy calculated from the quantum theory for inelastic collisions based on the first-order (plane-wave) Born approximation for charged particles with individual atoms and molecules. Our results show that the cylindrical geometry is more suitable for carrying out such a study. Moreover, we developed an analytical expression for the 131 iodine gamma dose (the energy deposited per photon absorbed dose). This latter could be considered as an important tool for evaluating the gamma dose without going through stochastic models.

  2. 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

  3. Estimation of absorbed radiation dose rates in wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi nuclear power plant accident

    International Nuclear Information System (INIS)

    The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium (134Cs and 137Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h−1 (1.2 mGy d−1), even 3 years after

  4. Direct determination of internal radiation dose in human blood

    CERN Document Server

    Tanır, Ayse Güneş

    2014-01-01

    The purpose of this study is to measure the internal radiation dose using a human blood sample. In the literature, there is no process that allows the direct measurement of the internal radiation dose received by a person. The luminescence counts from a blood sample having a laboratory-injected radiation dose and the waste blood of the patient injected with a radiopharmaceutical for diagnostic purposes were both measured. The decay and dose-response curves were plotted for the different doses. The doses received by the different blood aliquots can be determined by interpolating the luminescence counts to the dose-response curve. This study shows that the dose received by a person can be measured directly, simply and retrospectively by using only a very small amount of blood sample. The results will have important ramifications for the medicine and healthcare fields in particular. This will also be very important in cases of suspicion of radiation poisoning, malpractice and so on.

  5. A new method for evaluating annual absorbed gamma dose rates in an archaeological site by combining the SSNTD technique with Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Misdaq, M.A.; Fahde, K.; Erramli, H. [Nuclear Physics and Techniques Laboratory, Faculty of Sciences Semlalia, B.P. S15, University Cadi Ayyad, Marrakech (Morocco); Mikdad, A. [National Institute of Archaeology and Patrimony, Rabat (Morocco); Rzama, A.; Yousif Charif, M.L. [National Centre of Radioprotection, Rabat (Morocco)

    1998-10-01

    Uranium and thorium contents in different layers of an archaeological site have been determined by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and calculating the probabilities for {alpha}-particles emitted by the uranium and thorium series to reach and be registered on the SSNTD films. A new method has been developed based on calculating the self-absorption coefficient of the gamma-photons emitted by the uranium ({sup 238}U), thorium ({sup 232}Th) and their corresponding decay products as well as the potassium-40 ({sup 40}K) isotope for evaluating the annual absorbed gamma dose rates in the considered material samples. Results obtained have been compared with data obtained by using the TL dosimetry and Bell's methods. Ceramic samples belonging to the studied archaeological site have been dated.

  6. A new method for evaluating annual absorbed gamma dose rates in an archaeological site by combining the SSNTD technique with Monte Carlo simulations

    CERN Document Server

    Misdaq, M A; Erramli, H; Mikdad, A; Rzama, A; Yousif-Charif, M L

    1998-01-01

    Uranium and thorium contents in different layers of an archaeological site have been determined by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) and calculating the probabilities for alpha-particles emitted by the uranium and thorium series to reach and be registered on the SSNTD films. A new method has been developed based on calculating the self-absorption coefficient of the gamma-photons emitted by the uranium ( sup 2 sup 3 sup 8 U), thorium ( sup 2 sup 3 sup 2 Th) and their corresponding decay products as well as the potassium-40 ( sup 4 sup 0 K) isotope for evaluating the annual absorbed gamma dose rates in the considered material samples. Results obtained have been compared with data obtained by using the TL dosimetry and Bell's methods. Ceramic samples belonging to the studied archaeological site have been dated.

  7. Study of dose levels absorbed by members of the public in the nuclear medicine departments

    International Nuclear Information System (INIS)

    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)

  8. 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

  9. 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. 

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

    Science.gov (United States)

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

    2006-09-01

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

  11. Experimental ratio between the 'real' dose per organ and the calculated dose determined by means of the Embalse nuclear power plant's personal dosimeter

    International Nuclear Information System (INIS)

    The specific purpose of the study was to determine the experimental ratio between the reading of dosimeters used by the personnel of the Embalse nuclear power plant and the 'real' dose absorbed by the worker in different organs. An anthropomorphic phantom ALDERSON internal and externally loaded with approximately 150 TLD crystals was used. This phantom was placed in five enclosures that were usually occupied by workers of the Embalse nuclear power plant. In this way, the average dose per organ and the effective equivalent dosis in each enclosure could be calculated and compared with the personal dosimeters placed over the thorax and the conversion factor rem/rem for each enclosure was determined. The average factor resulting from the five considered enclosures was 0.73 rem/rem. This means that the personal dosimeters over value the real dosis absorbed by the personnel of the Embalse nuclear power plant in approximately 37%. (Author)

  12. 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.

  13. Comparison of radiation absorbed dose in target organs in maxillofacial imaging with panoramic, conventional linear tomography, cone beam computed tomography and computed tomography

    Directory of Open Access Journals (Sweden)

    Panjnoush M.

    2009-12-01

    Full Text Available "nBackground and Aim: The objective of this study was to measure and compare the tissue absorbed dose in thyroid gland, salivary glands, eye and skin in maxillofacial imaging with panoramic, conventional linear tomography, cone beam computed tomography (CBCT and computed tomography (CT."nMaterials and Methods: Thermoluminescent dosimeters (TLD were implanted in 14 sites of RANDO phantom to measure average tissue absorbed dose in thyroid gland, parotid glands, submandibular glands, sublingual gland, lenses and buccal skin. The Promax (PLANMECA, Helsinki, Finland unit was selected for Panoramic, conventional linear tomography and cone beam computed tomography examinations and spiral Hispeed/Fxi (General Electric,USA was selected for CT examination. The average tissue absorbed doses were used for the calculation of the equivalent and effective doses in each organ."nResults: The average absorbed dose for Panoramic ranged from 0.038 mGY (Buccal skin to 0.308 mGY (submandibular gland, linear tomography ranged from 0.048 mGY (Lens to 0.510 mGY (submandibular gland,CBCT ranged from 0.322 mGY (thyroid glad to 1.144 mGY (Parotid gland and in CT ranged from 2.495 mGY (sublingual gland to 3.424 mGY (submandibular gland. Total effective dose in CBCT is 5 times greater than Panoramic and 4 times greater than linear tomography, and in CT, 30 and 22 times greater than Panoramic and linear tomography, respectively. Total effective dose in CT is 6 times greater than CBCT."nConclusion: For obtaining 3-dimensional (3D information in maxillofacial region, CBCT delivers the lower dose than CT, and should be preferred over a medical CT imaging. Furthermore, during maxillofacial imaging, salivary glands receive the highest dose of radiation.

  14. Quantum size effects in Pb layers with absorbed Kondo adatoms: Determination of the exchange coupling constant

    KAUST Repository

    Schwingenschlögl, Udo

    2009-07-01

    We consider the magnetic interaction of manganese phtalocyanine (MnPc) absorbed on Pb layers that were grown on a Si substrate. We perform an ab initio calculation of the density of states and Kondo temperature as a function of the number of Pb monolayers. Comparison to experimental data [Y.-S. Fu et al., Phys. Rev. Lett. 99, 256601 (2007)] then allows us to determine the exchange coupling constant J between the spins of the adsorbed molecules and those of the Pb host. This approach gives rise to a general and reliable method for obtaining J by combining experimental and numerical results.

  15. 10 CFR 20.2104 - Determination of prior occupational dose.

    Science.gov (United States)

    2010-01-01

    ... annual occupational dose requiring monitoring under § 20.1502, the licensee shall determine the occupational radiation dose received during the current year. (b) Prior to permitting an individual to... must show each period in which the individual received occupational exposure to radiation...

  16. Determining effective radiation mutagen dose for garlic (Allium sativum L.)

    International Nuclear Information System (INIS)

    This study was carried out to get database for future garlic mutation breeding studies. For this aim, 0, 5, 10, 15, 20, 25 and 30 Gy doses of Cs137 (gamma-ray) were applied on garlic cloves as a physical mutagen. 50 cloves were used for each dose. Sixty days after treatment, germination rate and shoot development of cloves were determined. The Effective Mutagen Dose (ED50) was calculated by regression analyses. According to the results, 4.455 Gy dose was found to be effective as ED50. (author)

  17. 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

  18. Development and verification of an analytical algorithm to predict absorbed dose distributions in ocular proton therapy using Monte Carlo simulations.

    Science.gov (United States)

    Koch, Nicholas C; Newhauser, Wayne D

    2010-02-01

    Proton beam radiotherapy is an effective and non-invasive treatment for uveal melanoma. Recent research efforts have focused on improving the dosimetric accuracy of treatment planning and overcoming the present limitation of relative analytical dose calculations. Monte Carlo algorithms have been shown to accurately predict dose per monitor unit (D/MU) values, but this has yet to be shown for analytical algorithms dedicated to ocular proton therapy, which are typically less computationally expensive than Monte Carlo algorithms. The objective of this study was to determine if an analytical method could predict absolute dose distributions and D/MU values for a variety of treatment fields like those used in ocular proton therapy. To accomplish this objective, we used a previously validated Monte Carlo model of an ocular nozzle to develop an analytical algorithm to predict three-dimensional distributions of D/MU values from pristine Bragg peaks and therapeutically useful spread-out Bragg peaks (SOBPs). Results demonstrated generally good agreement between the analytical and Monte Carlo absolute dose calculations. While agreement in the proximal region decreased for beams with less penetrating Bragg peaks compared with the open-beam condition, the difference was shown to be largely attributable to edge-scattered protons. A method for including this effect in any future analytical algorithm was proposed. Comparisons of D/MU values showed typical agreement to within 0.5%. We conclude that analytical algorithms can be employed to accurately predict absolute proton dose distributions delivered by an ocular nozzle.

  19. Development and verification of an analytical algorithm to predict absorbed dose distributions in ocular proton therapy using Monte Carlo simulations

    International Nuclear Information System (INIS)

    Proton beam radiotherapy is an effective and non-invasive treatment for uveal melanoma. Recent research efforts have focused on improving the dosimetric accuracy of treatment planning and overcoming the present limitation of relative analytical dose calculations. Monte Carlo algorithms have been shown to accurately predict dose per monitor unit (D/MU) values, but this has yet to be shown for analytical algorithms dedicated to ocular proton therapy, which are typically less computationally expensive than Monte Carlo algorithms. The objective of this study was to determine if an analytical method could predict absolute dose distributions and D/MU values for a variety of treatment fields like those used in ocular proton therapy. To accomplish this objective, we used a previously validated Monte Carlo model of an ocular nozzle to develop an analytical algorithm to predict three-dimensional distributions of D/MU values from pristine Bragg peaks and therapeutically useful spread-out Bragg peaks (SOBPs). Results demonstrated generally good agreement between the analytical and Monte Carlo absolute dose calculations. While agreement in the proximal region decreased for beams with less penetrating Bragg peaks compared with the open-beam condition, the difference was shown to be largely attributable to edge-scattered protons. A method for including this effect in any future analytical algorithm was proposed. Comparisons of D/MU values showed typical agreement to within 0.5%. We conclude that analytical algorithms can be employed to accurately predict absolute proton dose distributions delivered by an ocular nozzle.

  20. 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

  1. 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

  2. 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

    International Nuclear Information System (INIS)

    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 (2H+) 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 BodyBuilderTM 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. (authors)

  3. Relation between absorbed dose, charged particle equilibrium and nuclear transformations: a non-equilibrium thermodynamics point of view.

    Science.gov (United States)

    Alvarez-Romero, J T

    2006-01-01

    We present a discussion to show that the absorbed dose D is a time-dependent function. This time dependence is demonstrated based on the concepts of charged particle equilibrium and on radiation equilibrium within the context of thermodynamic non-equilibrium. In the latter, the time dependence is due to changes of the rest mass energy of the nuclei and elementary particles involved in the terms summation operator Q and Q that appear in the definitions of energy imparted epsilon and energy deposit epsilon(i), respectively. In fact, nothing is said about the averaging operation of the non-stochastic quantity mean energy imparted epsilon, which is used in the definition of D according to ICRU 60. It is shown in this research that the averaging operation necessary to define the epsilon employed to get D cannot be performed with an equilibrium statistical operator rho(r) as could be expected. Rather, the operation has to be defined with a time-dependent non-equilibrium statistical operator rho(r, t); therefore, D is a time-dependent function D(r,t). PMID:16731692

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

    Science.gov (United States)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2015-12-01

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

  5. Air kerma and absorbed dose on the torso of a patient during a mammography study;Kerma en aire y dosis absorbida en el torso de una paciente durante un estudio mastografico

    Energy Technology Data Exchange (ETDEWEB)

    Hernadez O, M.; Duran M, H. A.; Pinedo S, A.; Gonzalez G, R.; Guerra M, J. A.; Salas L, M. A.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, 11500 Mexico D. F. (Mexico); Azorin N, J., E-mail: mar_h2o@hotmail.co [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, 09340 Mexico D. F. (Mexico)

    2009-10-15

    Two dosimetric magnitudes, due to the dispersed radiation, have been determined during a mammography study. The magnitudes that were determined are the kerma at the entrance of the torso and the absorbed dose by the torso. This determination was made in a paraffin phantom and with thermoluminescent dosemeters. One of the important parameters in the radiological protection of a patient to which is practiced a mammography is the value of the media glandular dose. However, during the taking of the X-ray a radiation portion that impacts on the mammary gland it is dispersed toward the patient's torso. In this work thermoluminescent dosemeters of ZrO{sub 2} has been used to determine the kerma at the entrance of the torso like the absorbed dose. The dosemeters was placed on the surface of the torso phantom while to the mamma phantom was made the mammography. As mamma phantom was used glucose serum to 5%. Of the obtained results we find that 3% of the air kerma at the entrance of the mamma it corresponds at the air kerma that receives the torso and 3.2% of the media glandular dose it is the absorbed dose of the same one. Another important result is the percentage value of the air kerma on the entrance of the thyroid area during a mammography, due to the dispersed radiation, it is 4% of the kerma at the entrance of the mamma. The air kerma at the entrance of the thyroid is of 0.41 +-0.07 mGy, 10% of this value corresponds to the absorbed dose by the thyroid. Therefore, it is observed that the media glandular dose and the air kerma at the entrance of the mamma they influence on the dispersed radiation toward the torso. Also, the superior part of the torso has less attenuation capacity to the dispersed radiation that those located in the inferior part. Therefore, the thyroid receives the major quantity of air kerma at the entrance. (Author)

  6. 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

    International Nuclear Information System (INIS)

    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 (3He2+) 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 BodyBuilderTM 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. Published by Oxford Univ. Press on behalf of the U.S. Government 2010. (authors)

  7. 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

    International Nuclear Information System (INIS)

    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 (3H+) 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 BodyBuilderTM 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. Published by Oxford Univ. Press on behalf of the US Government 2010. (authors)

  8. Determination of crossed gamma doses for garlic improvement (Allium Sativum)

    International Nuclear Information System (INIS)

    The determination of four Cuban varieties of garlic was made so as to optimized the use of ionizing radiations in Cuba to breed vegetatively propagated crops such as garlic. The dose-effect regresion equation characterizing the radioinhibition zone of each crop was presented. We used a criteria to select the irradiation dose to be used in mutation breeding techniques based on obtaining height variability in the productive indicators, a survival and a number of garlic cloves high enough to allow and adequate reproduction of M1 plants. It was verified that this small inhibitor doses of radiations produced a higher percentage of good variability than the medium and high doses. With the use of small inhibitor doses (GR10-GR20) on the Guadalupe-15 garlic variety, 65 variety plants were obtained., 93.7% out of this number is higher than the control in the indicators considered

  9. 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)

  10. 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

  11. Standardized methods to verify absorbed dose in irradiated food for insect control. Proceedings of a final research co-ordination meeting

    International Nuclear Information System (INIS)

    Irradiation to control insect infestation of food is increasingly accepted and applied, especially as a phytosanitary treatment of food as an alternative to fumigation. However, unlike other processes for insect control, irradiation does not always result in immediate insect death. Thus, it is conceivable that fresh and dried fruits and tree nuts, which have been correctly irradiated to meet insect disinfestation/quarantine requirements, may still contain live insects at the time of importation. There is, however, a movement by plant quarantine authorities away from inspecting to ensure the absence of live insects in imported consignments towards examining through administrative procedures that a treatment required by law has been given. Nevertheless, there is a need to provide plant quarantine inspectors with a reliable objective method to verify that a minimum absorbed dose of radiation was given to supplement administrative procedures. Such an objective method is expected to bolster the confidence of the inspectors in clearing the consignment without delay and to facilitate trade in irradiated commodities. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture initiated a co-ordinated research project (CRP) in 1994 to generate data on the verification of absorbed dose of irradiation in fresh, dried fruits and tree nuts for insect disinfestation/quarantine purposes. A standardized label dose indicator available commercially was used to verify the minimum/maximum absorbed dose of the irradiated commodities for these purposes as required by regulations in certain countries. It appears that such a label dose indicator with certain modifications could be made available to assist national authorities and the food industry to verify the absorbed dose of irradiation to facilitate trade in such irradiated commodities. This TECDOC reports on the accomplishments of this co-ordinated research project and includes the papers presented by the participants

  12. Direct determination of radiation dose in human blood

    CERN Document Server

    Tanir, Ayse Gunes; Sahiner, Eren; Bolukdemir, Mustafa Hicabi; Koc, Kemal; Meric, Niyazi; Kelec, Sule Kaya

    2014-01-01

    Our purpose is to measure the internal radiation dose (ID) using human blood sample. In the literature, there is no process that allows the direct measurement of ID received by a person. This study has shown that it is possible to determine ID in human blood exposed to internal or external ionizing radiation treatment both directly and retrospectively. OSL technique was used to measure the total dose from the blood sample. OSL counts from the waste blood of the patient injected with a radiopharmaceutical for diagnostic or treatment purposes and from a blood sample having a laboratory-injected radiation dose were both used for measurements. The decay and dose-response curves (DRC) were plotted for different doses. The doses received by different blood aliquots have been determined by interpolating the natural luminescence counts to DRC. In addition, OSL counts from a healthy blood sample exposed to an external radiation source were measured. The blood aliquots were given different 0-200Gy beta doses and their ...

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

    International Nuclear Information System (INIS)

    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 137Cs and 1845-101220 Bq/kg of 90Sr. In fish of cooling pond the concentration of 137Cs registered in range 750-4200 and 90Sr - 41-512 Bq/kg. In ichthyofauna of water bodies which concern to the third group, specific activity of 137Cs and 90Sr 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 137Cs in fish of the fifth and sixth groups were accordingly 25-159 and 11-224 as well as 90Sr - 36-174 and 3-14 Bq/kg. The ratio of specific activity of 90Sr/137Cs 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 90Sr - 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 ecosystems where it makes for different species from 2.8 (pelagic fish) to

  14. Dose distribution determination of ruthenium-106 ophthalmic applicators

    International Nuclear Information System (INIS)

    Full text: Dose distributions of COB and CCA type ruthenium-106 ophthalmic applicators (15 and 20 mm diameter) were investigated using small thin CaSO4:Dy thermoluminescent dosimeters with dimensions of approximately 2 x 3 x 0.05 mm3. TLD characteristics, namely linearity, reproducibility and sensitivity were studied. Measured sensitivities (variations in response to a nominal dose due to differences in size, homogeneity, etc) of individual TLD discs ranged from approximately -20% to +17%. TLDs were then placed at different positions in a water equivalent eye phantom. Dose points in planes at 1 to 10 mm depths from the plaque active surface were measured. Hot spots and cold spots (up to 50% difference from the dose on the central axis) were found in various positions throughout the plaques. The depth dose values provided by the manufacturer agreed well with the measured ones, but the standard errors for TLD measurements were considerably less than that of manufacturer. The percentage uncertainty obtained with proposed method was on average better than 5% compared to 30% indicated by manufacturer. MOSFET semiconductor detector was also employed in determination of Percentage Depth Dose (PDD) of the plaques. This was found to be a very feasible dosimetry method providing fast readout and high sensitivity to low radiation doses. The measurements agreed within a few percent with TLD results and manufacturer provided data. Determination of dose distributions of ruthenium-106 applicators using small CaSO4:Dy TLDs proved to be a useful technique for estimation of 2D dose distributions resulting from plaque treatments. On the other hand, fast measurement of PDD using MOSFET detector can be used for regular quality assurance and acceptance testing of the plaques

  15. Calculation of absorbed dose for skin contamination imparted by beta radiation through the VARSKIN modified code for 122 interesting isotopes for nuclear medicine, nuclear power plants and research

    International Nuclear Information System (INIS)

    In this work the implementation of a modification of the VARSKIN code for calculation of absorbed dose for contamination in skin imparted by external radiation fields generated by Beta emitting is presented. The modification consists on the inclusion of 47 isotopes of interest even Nuclear Plants for the dose evaluation in skin generated by 'hot particles'. The approach for to add these isotopes is the correlation parameter F and the average energy of the Beta particle, with relationship to those 75 isotopes of the original code. The methodology of the dose calculation of the VARSKIN code is based on the interpolation, (and integration of the interest geometries: punctual or plane sources), of the distribution functions scaled doses in water for beta and electrons punctual sources, tabulated by Berger. Finally a brief discussion of the results for their interpretation and use with purposes of radiological protection (dose insurance in relation to the considered biological effects) is presented

  16. 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.

  17. 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. PMID:27134562

  18. Games with gammas: problems in environmental gamma dose determination

    International Nuclear Information System (INIS)

    The evaluation of the environmental dose rate is fundamental to ESR, OTL and TL dating, but results from different measurement methods, independently calibrated, are not always consistent. Some field measurements of environmental dose rate using a Canberra field gamma spectrometer are compared with those obtained using TLD and show a systematic discrepancy close to a factor of two. Possible reasons for the discrepancy are discussed but none offers a sufficiently substantial adjustment to reconcile the disagreement in the results given by the two methods. Comparison with dose rates estimated from radionuclide concentrations could not determine which method was more accurate as the correlation between these estimates and the previous ones was negligible, casting some doubt on the accuracy of the concentration estimates. The danger of relying on a single method of estimating dose rate without careful cross-calibration is highlighted. (author)

  19. Determination of dose equivalent via linear energy transfer (LET) spectrometry using CR-39 detectors

    International Nuclear Information System (INIS)

    For neutron dosimetry, the measurement of detailed energy distribution is preferred which is then converted to dose by folding with suitable conversion coefficients. This approach needs the detectors capable of discriminating different types of radiations and also the use of complex mathematical procedures (unfolding) to generate the neutron spectra. However, in situations where the energy distribution is difficult to measure and/or as a supplement to the above method, the dose values can also be determined by measuring the absorbed dose and the linear energy transfer (LET) in the medium, and convening to equivalent dose with conversion coefficients based on relative biological effectiveness (RBE). Since RBE depends on the LET of the ionizing radiation, analysis of the LET spectrum is a more direct way of defining the radiation quality. This method is simpler and convenient as it neither requires the discrimination of different radiation components nor the unfolding procedures. In this work, the LET spectrum in water in the range of 12 keV/μm to 382 keV/μm due to 14 MeV (D-T) neutrons is estimated using the track size parameters in different types of CR-39 track detectors. The effect of additional polyethylene (PE) radiator on the LET spectrum is also studied. The detection sensitivity, LET spectra and microdosimetric characteristics are presented and the dose equivalent values are compared with that obtained using a neutron rem meter. (author)

  20. Calculations radiobiological using the quadratic lineal model in the use of the medium dose rate absorbed in brachytherapy. Pt. 3

    International Nuclear Information System (INIS)

    Calculations with the quadratic lineal model for medium rate using the equation dose-effect. Several calculations for system of low dose rate brachytherapy plus teletherapy, calculations for brachytherapy with medium dose rate together with teletherapy, dose for fraction and the one numbers of fractions in medium rate

  1. Synthesis of poly (acrylamide-co-metacrylic acid) hydrogels By means of gamma irradiation techniques: influence of Absorbed dose on the swelling process

    International Nuclear Information System (INIS)

    In this report gamma radiation techniques were performed a double function of proceeding the processes of polymerization and crosslinking with the advantage of avoid the uses of chemicals crosslinks. The influence of absorbed dose on the swelling ratio as a function of pH have been presented. For these hydrogels, swelling studies indicated that swelling decrease with the increase of the absorbed dose from 10 to 50 kGy. It was confirmed that at the firsts stages (100-150 min) the diffusion studies were in accordance with Fickian behavior and the diffusion coefficients were obtained, whereas the latest stages were in good agreement with second-order diffusion kinetics proposed by Schott 1 .These news hydrogels exhibit a higher degree of swelling, a factor that, a priori, assures high biocompatibility because it increases the similarity with living tissues

  2. Absorbed dose assessment of 177Lu-zoledronate and 177Lu-EDTMP for human based on biodistribution data in rats

    OpenAIRE

    Yousefnia, Hassan; Zolghadri, Samaneh; Jalilian, Amir Reza

    2015-01-01

    Over the past few decades, several bone-seeking radiopharmaceuticals including various bisphosphonate ligands and β-emitting radionuclides have been developed for bone pain palliation. Recently, 177Lu was successfully labeled with zoledronic acid (177Lu-ZLD) as a new generation potential bisphosphonate and demonstrated significant accumulation in bone tissue. In this work, the absorbed dose to each organ of human for 177Lu-ZLD and 177Lu-ethylenediaminetetramethylene phosphonic acid (177Lu-EDT...

  3. Statistical methodology to determine kinetically derived maximum tolerated dose in repeat dose toxicity studies.

    Science.gov (United States)

    McFadden, Lisa G; Bartels, Michael J; Rick, David L; Price, Paul S; Fontaine, Donald D; Saghir, Shakil A

    2012-07-01

    Several statistical approaches were evaluated to identify an optimum method for determining a point of nonlinearity (PONL) in toxicokinetic data. (1) A second-order least squares regression model was fit iteratively starting with data from all doses. If the second order term was significant (αmodel was fit iteratively starting with data from all doses except the highest. The mean response for the omitted dose was compared to the 95% prediction interval. If the omitted dose falls outside the confidence interval it is an estimate of the PONL. (3) Slopes of least squares linear regression lines for sections of contiguous doses were compared. Nonlinearity was suggested when slopes of compared sections differed. A total of 33 dose-response datasets were evaluated. For these toxicokinetic data, the best statistical approach was the least squares regression analysis with a second-order term. Changing the α level for the second-order term and weighting the second-order analysis by the inverse of feed consumption were also considered. This technique has been shown to give reproducible identification of nonlinearities in TK datasets.

  4. Equivalent dose determination using a quartz isothermal TL signal

    DEFF Research Database (Denmark)

    Vandenberghe, D.A.G.; Jain, Mayank; Murray, A.S.

    2009-01-01

    We report on further developments in the use of an isothermal thermoluminescence (ITL) signal for determining the equivalent dose (De) in unheated sedimentary quartz. In order to minimise sensitivity change during the first measurement, the ITL signal is measured at 270 °C following a preheat at ...... the same age range as the OSL signal, and it appears especially advantageous for application to quartz samples for which the OSL signal saturates below 500 Gy.......We report on further developments in the use of an isothermal thermoluminescence (ITL) signal for determining the equivalent dose (De) in unheated sedimentary quartz. In order to minimise sensitivity change during the first measurement, the ITL signal is measured at 270 °C following a preheat...... signal can be fully reset by sunlight, and grows with dose over at least the same range as the OSL signal. A single-aliquot regenerative-dose (SAR) protocol can be used with this ITL signal. Dose recovery experiments confirm the suitability of the measurement protocol; the De values are in acceptable...

  5. Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Kleiman, Norman Jay [Columbia University

    2013-11-30

    The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

  6. Measurement of neutron and gamma-ray absorbed doses inside human body in criticality accident situations using phantom and tissue-equivalent dosimeters

    International Nuclear Information System (INIS)

    Personal dosimeters provide a fundamental evaluation of external exposures to human bodies in radiation accidents. For emergency medical treatment to heavily exposed patients, the evaluation of dose distribution inside the body has been tried by computational simulations. Experimental data on dose distributions inside the body are necessary for accurate simulation of human dosimetry, particularly in complex radiation fields of neutrons and gamma-rays such as criticality accidents. A preliminary experiment on the human dosimetry was carried out at the Transient Experiment Critical Facility (TRACY) to acquire such experimental data in criticality accident situations. A combined use of two kinds of tissue-equivalent dosimeters together with a human phantom was employed to measure neutron and gamma-ray absorbed doses inside the body. The neutron and gamma-ray absorbed doses measured on the phantom were found to be in roughly the same level as those averaged over the phantom inside or those measured in free air. The dose distributions measured inside and on the phantom could be qualitatively interpreted from reflection an attenuation of neutrons and gamma-rays in the phantom, neutron-induced secondary gamma-rays emitted in the phantom, and so forth. (author)

  7. KEY COMPARISON: Comparison of the standards for absorbed dose to water of the ENEA-INMRI (Italy) and the BIPM for 60Co γ rays

    Science.gov (United States)

    Kessler, C.; Allisy-Roberts, P. J.; Burns, D. T.; Guerra, A. S.; Laitano, R. F.; Pimpinella, M.

    2010-01-01

    A comparison of the standards for absorbed dose to water of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI), and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co gamma radiation under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result, based on the calibration coefficients for three transfer standards and expressed as a ratio of the ENEA and the BIPM standards for absorbed dose to water, is 0.9999 (0.0044). The present 2007 result replaces the earlier ENEA value in this key comparison. The degrees of equivalence between the ENEA 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) that have published results in this 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 the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  8. 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

    International Nuclear Information System (INIS)

    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 103 μGy/y has been used. The derived absorbed dose rate calculated for tilapia was 2.76 x 100 μGy/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)

  9. Performance evaluation of the QC-6PLUS quality control system in terms of photons and electrons absorbed doses to water

    International Nuclear Information System (INIS)

    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)

  10. 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.

  11. Dose Rate Determination from Airborne Gamma-ray Spectra

    DEFF Research Database (Denmark)

    Bargholz, Kim

    1996-01-01

    The standard method for determination of ground level dose rates from airborne gamma-ray is the integral count rate which for a constant flying altitude is assumed proportional to the dose rate. The method gives reasonably results for natural radioactivity which almost always has the same energy...... distribution. When manmade radioactivity is present, this is no longer the case. Another method based on giving the counts of different channels a different weighting has been examined. The new method is more robust against varying energy distribution, and for energies above 200 keV it gives excellent results....

  12. 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)

  13. 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)

  14. 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

  15. 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)

  16. Monte Carlo simulation methods of determining red bone marrow dose from external radiation

    International Nuclear Information System (INIS)

    Objective: To provide evidence for a more reasonable method of determining red bone marrow dose by analyzing and comparing existing simulation methods. Methods: By utilizing Monte Carlo simulation software MCNPX, the absorbed doses of red hone marrow of Rensselaer Polytechnic Institute (RPI) adult female voxel phantom were calculated through 4 different methods: direct energy deposition.dose response function (DRF), King-Spiers factor method and mass-energy absorption coefficient (MEAC). The radiation sources were defined as infinite plate.sources with the energy ranging from 20 keV to 10 MeV, and 23 sources with different energies were simulated in total. The source was placed right next to the front of the RPI model to achieve a homogeneous anteroposterior radiation scenario. The results of different simulated photon energy sources through different methods were compared. Results: When the photon energy was lower than 100 key, the direct energy deposition method gave the highest result while the MEAC and King-Spiers factor methods showed more reasonable results. When the photon energy was higher than 150 keV taking into account of the higher absorption ability of red bone marrow at higher photon energy, the result of the King-Spiers factor method was larger than those of other methods. Conclusions: The King-Spiers factor method might be the most reasonable method to estimate the red bone marrow dose from external radiation. (authors)

  17. A water calorimeter for on-site absorbed dose to water calibrations in (60)Co 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 (60)Co 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 (60)Co beam and on-site in clinical MV-photon beams. Excellent agreement of 0.1% was achieved with previous (60)Co 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 (60)Co 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%. PMID:27300589

  18. 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%.

  19. 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.)

  20. 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.

  1. Austrian results from Matroshka poncho and organ dose determination

    Science.gov (United States)

    Hajek, M.; Bergmann, R.; Fugger, M.; Vana, N.

    Cosmic rays in low-earth orbits LEO primarily consist of high-energy charged particles originating from galactic cosmic radiation GCR energetic solar particle events SPE and trapped radiation belts These radiations of high linear energy transfer LET generally inflict greater biological damage than that resulting from typical terrestrial radiation hazards Particle and energy spectra are attenuated in interaction processes within shielding structures and within the human body Reliable assessment of health risks to astronaut crews is pivotal in the design of future expeditions into interplanetary space and requires knowledge of absorbed radiation doses in critical radiosensitive organs and tissues The European Space Agency ESA Matroshka experiment---conducted under the aegis of the German Aerospace Center DLR ---is aimed at simulating an astronaut s body during extravehicular activities EVA Matroshka basically consists of a human phantom torso attached to a base structure and covered with a protective carbon-fibre container acting as a spacesuit model The phantom is divided into 33 tissue-equivalent polyurethane slices of specific density for tissue and organs Natural bones are embedded Channels and cut-outs enable accommodation of active and passive radiation monitors The torso is dressed by a skin-equivalent poncho which is also designed for dosimeter integration The phantom houses in total 7 active and more than 6000 passive radiation sensors Thereof the Atomic Institute of the Austrian Universities ATI provided more than

  2. Determinations of H(10) and its dose components onboard aircraft.

    Science.gov (United States)

    Lindborg, L; Beck, P; Bottolier-Depois, J F; Latocha, M; Lillhök, J; Rollet, S; Roos, H; Roth, J; Schraube, H; Spurny, F; Stehno, G; Trompier, F; Wissmann, F

    2007-01-01

    Aircrew is in general receiving a higher average annual dose than other occupationally exposed personnel, and about half of the effective dose is deposited by high-LET neutron secondaries. A recent investigation of the cancer incidence following the atomic bombs at Hiroshima and Nagasaki has put forward the possibility that the relative biological efficiency for neutrons could be underestimated. If so, the effective dose to aircrew from this component would increase and the estimation of this component will become even more important. Different ambient dose equivalent measurement techniques and calculation methods have recently been compared on a dedicated flight. The experimental results are compared with calculations made with the codes EPCARD 3.2 and an updated version of FLUKA and different galactic proton spectra. The aircraft circulated within the target areas at two constant altitudes with a flight route variation of only about 1 degrees in longitude and latitude to reduce the influence from variations in atmospheric and geomagnetic shielding. The instrumentation consisted of tissue-equivalent proportional counters (TEPC) and a silicon diode spectrometer. Measurements were performed for 2 h to reduce the statistical uncertainties in the results. The TEPCs were evaluated either according to single-event analysis techniques or the variance-covariance method. Besides the total ambient dose equivalent, the instruments can be evaluated to reveal the low- and high-LET components. The EPCARD and FLUKA simulations can determine the contribution from each type of particle directly. The ratio between the calculated and the measured average value of the ambient dose equivalent rate was 1.00 +/- 0.08 with all instruments included for EPCARD and 0.97 +/- 0.07 when FLUKA was used. The measured high-LET component and the calculated neutron component are not quite identical, but should be similar. The agreement was always within 20%. The high-LET component contributed with

  3. 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

    International Nuclear Information System (INIS)

    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 Km2. 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-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)

  4. 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)

  5. 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 177Lu- and 90Y-BR96 mAbs

    International Nuclear Information System (INIS)

    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 90Y- and 177Lu-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 177Lu and 12.5 Gy for 90Y. 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 weight, ranging from

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

    International Nuclear Information System (INIS)

    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 an192Ir 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 192Ir 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 an192Ir source. Finally, an experimental system was designed to irradiate TLDs at different angles between 1 and 11 cm away from an 192Ir 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 192Ir 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 standard137Cs beam provided an estimated mean uncertainty of 2.8% (k = 1) in the TLD calibration coefficient for irradiations by the 192Ir source in water. The 3D TLD measurements performed in liquid water were obtained with a maximum uncertainty of 11% (k = 1) found

  7. 空气伽马吸收剂量率影响因素研究%Influencing Factors of the Gamma Air-Absorbed Dose Rate

    Institute of Scientific and Technical Information of China (English)

    殷荫; 王南萍; 付宸; 储星铭

    2012-01-01

    The influencing factors of gamma air-absorbed dose rate are studied to improve the precision of environmental radiation monitoring data. Background radiation measurement, increasing of the radon concentration and changing of humidity are done to discuss the two major influencing factors, I. e. the concentration and relative humidity of radon and radon progeny in the air. The radon concentration in the air are measured with scintillation radon monitor ( ZnS ( Ag) ) , electronic radon detector ( RAD7 ) and ionization chamber radon detector ( Alpha-GUARD) , and gamma air-absorbed dose rate with X--y dose rate meter (CKL-3120). The gamma air-absorbed dose rate, radon concentration, temperature, relative humidity and atmospheric pressure in the air are monitored together. Results show gamma air-absorbed dose rate indicates a poor correlation with radon concentration and relative humidity of the air.%为提高辐射环境监测数据的准确度,对空气伽马吸收剂量率影响因素进行了研究.针对空气伽马吸收剂量率两个主要影响参数一空气氡及其子体浓度和相对湿度,分另別进行了室内外本底测量、增加氡浓度和改变相对湿度实验.采用闪烁室测氡仪(ZnS(Ag)型)、静电收集室测氡仪(RAD7)和电离室测氡仪(AlphaGUARD)测量空气氡浓度,用X-γ剂量率仪( CKL-3120)测量空气伽马吸收剂量率.联合观测空气伽马吸收剂量率、空气氡浓度、温度、相对湿度和大气压强,实验结果表明:空气氡浓度、相对湿度与空气伽马吸收剂量率呈现弱的正相关.

  8. 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)

  9. Dynamic evaluation of absorbed dose to the bladder wall with a balloon-bladder phantom during a study using [(18)F]fluorodeoxyglucose positron emission imaging.

    Science.gov (United States)

    Wu, T H; Liu, R S; Dong, S L; Chung, Y W; Chou, K L; Lee, J S

    2002-08-01

    An accurate evaluation of the absorbed dose to the bladder wall from 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG) is clinically important because the bladder is considered as a critical organ in most positron emission tomography (PET) studies that cumulate about 20% of the total activity injection during image procedures. In the MIRD calculation, no allowance is made for the inclusion of all the dynamic parameters that affect the actual dose to the bladder wall to be taken in the dose assessment. The goal of the study is to propose a dose evaluation model by using a dynamic bladder phantom and time-activity curves from the bladder PET imaging. The proposed model takes all dynamic parameters into account and provides a much more accurate dose estimation to the bladder. In this study, the lowest dose to the bladder wall was obtained at the conditions of having a larger initial volume for the bladder contents and a higher production rate for urine. It is then advised patients to drink a bulk amount of water before the FDG injection or after urine voiding to facilitate urine production and to enlarge the bladder surface area, which are the most crucial steps in reducing the dose to the bladder wall. In our study, the voiding schedule in dose calculation plays certain roles although it is much more critical in the conventional MIRD calculation. The model estimated that the lowest dose to the bladder would occur at an initial void about 40 min after the FDG injection and the urine voiding was as complete as possible. PMID:12124480

  10. Imaging and profiling of absorbed dose in a tissue-equivalent GEL-phantom exposed to epithermal neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Palazzi, P. [Dip. Fisica Univ., Milano (Italy); Agosteo, S.; Mauri, M. [Politecnico, Milano (Italy); Rosi, G.; Nava, E.; Tinti, R. [ENEA, Casaccia (Italy)

    2000-10-01

    Last improvements are presented of the method for dose imaging and profiling in tissue-equivalent phantoms exposed to neutron fields suitable for BNCT. The method brings to separate knowledge of the various dose components of the secondary radiation induced by thermal or epithermal neutrons in tissue. (author)

  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

    ). To this spectrum was added some of the most relevant Auger and internal conversion electron emissions. On the other hand, an experimental array was used to simulate the presence or absence of fibrosis in a tumor of malignant cells (HeLa cells). With this model the retention of the radiopharmaceuticals {sup 177}Lu-Tyr{sup 3}-octreotate-gold nanoparticles (multimeric system) and {sup 177}Lu-Tyr{sup 3}-octreotate (monomeric system) in the micro environments (without fibrosis and with fibrosis) was determined. The experimental tumoral fibrosis array consists of a multilayer repetitive patter of HeLa cells, collagen and gelatin until completing a culture (in a trans well insert) layer by layer (Lbl) of five coatings of HeLa cells. The Lbl cultures were exposed during 24 h, approximate duplicating time of HeLa cells, separately to: {sup 177}LuCl{sub 3}, {sup 177}Lu-Tyr{sup 3}-octreotate, and {sup 177}Lu-Tyr{sup 3}-octreotate-gold nanoparticles with an initial activity of 26 MBq (700 μCi). The radiopharmaceutical retention was calculated by measuring the retained activity in the trans well inserts (radiopharmaceutical retained by HeLa cells and microenvironment) and in the lower chamber where the radiopharmaceutical permeated. The experimental models were essential to determine the radiopharmaceutical permeability which allowed the calculation of the retained activity fraction, and hence the cumulated activity in regions of interest for each of the different cases. This is needed at the same time for the radiation absorbed dose calculation. In this work it was concluded that the presence or absence of fibrosis and yet more, the multimeric and multivalent nature of the radiopharmaceutical had an effect on the radiation absorbed dose in the cell nucleus and in the tumor microenvironment. (Author)

  12. Estimation of absorbed dose using activity measured by PET for continuous inhalation of C{sup 15}O{sub 2} and {sup 15}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hachiya, Takenori [Rehabilitation Center for Physically Disabled Persons and Medical Center for Mental Health, Kyowa, Akita (Japan); Shoji, Yasuaki; Sasaki, Nobuo; Hagami, Eiichi; Toyoshima, Hideto; Hatazawa, Jun; Kanno, Iwao; Uemura, Kazuo

    1998-06-01

    In our positron emission tomography (PET) studies, measurement is carried out during C{sup 15}O{sub 2}, {sup 15}O{sub 2} and C{sup 15}O gas inhalation. The radiation absorbed dose was estimated by the MIRD method from measured cumulative radioactivity in organs and remainder of the body. The radiation absorbed dose in 22 target organs including pharynx, larynx and trachea walls were estimated using the radioactive concentration in 7 source organs (brain, pharynx-larynx, trachea, lung, heart, liver and remainder of the body). These radioactive concentrations in organs were measured by PET scan in a normal volunteer during continuous C{sup 15}O{sub 2} and {sup 15}O{sub 2} inhalation. The effective dose equivalents for 22 minutes of inhalation were found to be 5.81 x 10{sup -4} mSv/MBq for C{sup 15}O{sub 2} at 157 MBq/min and 4.64 x 10{sup -4} mSv/MBq for {sup 15}O{sub 2} inhaled at 294 MBq/min. (author)

  13. Using tissue equivalent proportional counters to determine dose equivalent

    International Nuclear Information System (INIS)

    Tissue equivalent proportional counters (TEPCs) have been used in the laboratory for over 30 years to determine neutron dose in mixed radiation fields, but they are seldom used by operational health physicists. But a number of TEPC-based instruments are being developed in Europe and in the United States. The purpose of this paper is: to introduce operational health physicists to tissue equivalent proportional counters, to examine some of the algorithms used to convert data from TEPCs into dose equivalent, to examine how TEPC measurements meet the requirements of DOE Order 5480.11 (DOE 1988) and 10CFR20, and to examine some of the TEPC-based instruments that are available. Many operational health physicists are not familiar with the concept of microdosimetry and the specialized terms that are used in analyzing the data from TEPCs, so a brief discussion is included. At present, quality factors are defined in terms of linear energy transfer, but TEPCs measure lineal energy

  14. Determination of the dose index in computerized tomography using thermoluminescent dosemeters; Determinacion del indice de dosis en tomografia computada usando dosimetros termoluminiscentes

    Energy Technology Data Exchange (ETDEWEB)

    Azorin, J.C.; Calderon, A. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN, 11500 Mexico D.F. (Mexico); Azorin, J. [UAM-I, 09340 Mexico D.F. (Mexico)

    2004-07-01

    In this work the obtained results of the determination of the dose index are presented in thorax studies in computed tomography and helical tomography carried out in Mexico using thermoluminescent dosemeters of LiF: Mg,Cu,P + Ptfe developed and manufactured in our country. The results showed that under similar conditions of irradiation and operation (pitch = 1), significant differences don't exist among the doses absorbed measures in the phantom due to the two types of used tomographs. (Author)

  15. 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.

  16. Decoloration and mineralization of reactive dyes using electron beam irradiation, Part I: Effect of the dye structure, concentration and absorbed dose (single, binary and ternary systems)

    Science.gov (United States)

    Vahdat, Ali; Bahrami, S. Hajir; Arami, M.; Bahjat, A.; Tabakh, F.; Khairkhah, M.

    2012-07-01

    In this study, three different reactive dyes (C.I. Reactive Red 4, C.I. Reactive Blue 2 and C.I. Reactive Yellow 4) and their blend solutions were irradiated with 10 MeV electron beam. Effect of absorbed dose, dye structure and primary solution concentrations on the pH value changes, degree of decoloration and chemical oxygen demand (COD) removal of solutions were investigated. Results show that this method is effective in decomposition and decoloration of the dyes solutions. This method can be applied in mineralization of wastewater containing different dyes.

  17. Role of cardiac ultrafast cameras with CZT solid-state detectors and software developments on radiation absorbed dose reduction to the patients

    International Nuclear Information System (INIS)

    Myocardial perfusion imaging (MPI) is one the most contributing nuclear medicine technique to the annual population dose. The purpose of this study is to compare radiation-absorbed doses to the patients examined by conventional cardiac SPECT (CSPECT) camera and ultrafast cardiac (UFC) camera with cadmium-zinc-telluride (CZT) solid-state detectors. Total injected activity was reduced by 50 % when both stress and rest images were acquired and by 75 % when only stress images were taken with UFC camera. As a result of this, the mean total effective dose was found significantly lower with UFC camera (2.2 ± 1.2 mSv) than CSPECT (7.7 ± 3.8 mSv) ( p < 0.001). Further dose reduction was obtained by reducing equivocal test results and unnecessary additional examinations with UFC camera. Using UFC camera, MPI can be conveniently used for the detection of coronary artery disease (CAD) much less increasing annual population radiation dose as it had been before. (authors)

  18. Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial artery access

    International Nuclear Information System (INIS)

    The aim of this study was to compare the radiation dose to patients during coronary angiography (CA) and coronary intervention (percutaneous transluminal coronary angioplasty, PTCA) by the femoral or radial artery access routes. A plane-parallel ionisation chamber, mounted on an under-couch X-ray tube (Siemens Coroskop TOP with an optional dose reduction system), recorded the dose-area product (DAP) to the patient from 40 coronary angiographies and 42 coronary interventions by the femoral route. The corresponding numbers for radial access were 36 and 24, respectively. Using a human-shaped phantom, conversion factors between maximum entrance surface dose and DAP were derived for CA and CA plus PTCA, respectively. The dose to the staff was measured with TL dosimeters for 22 examinations. Fluoroscopy time and DAP were significantly (p=0.003) larger using the radial access route for coronary angiography (7.5 min, 51 Gy cm2) than the corresponding values obtained from femoral access route (4.6 min, 38 Gy cm2). For CA plus PTCA the fluoroscopy time and DAP were larger for radial access (18.4 min, 75 Gy cm2) than for femoral access (12.5 min, 47 Gy cm2; p=0.013). In our experience, radial access did significantly prolong the fluoroscopy time and increase the patient doses. (orig.)

  19. Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial artery access

    Energy Technology Data Exchange (ETDEWEB)

    Sandborg, Michael; Pettersson, Haakan [Department of Radiation Physics, Faculty of Health Sciences and University Hospital, 58185, Linkoeping (Sweden); Fransson, Sven-Goeran [Department of Thoracic Radiology, University Hospital, 58185, Linkoeping (Sweden)

    2004-04-01

    The aim of this study was to compare the radiation dose to patients during coronary angiography (CA) and coronary intervention (percutaneous transluminal coronary angioplasty, PTCA) by the femoral or radial artery access routes. A plane-parallel ionisation chamber, mounted on an under-couch X-ray tube (Siemens Coroskop TOP with an optional dose reduction system), recorded the dose-area product (DAP) to the patient from 40 coronary angiographies and 42 coronary interventions by the femoral route. The corresponding numbers for radial access were 36 and 24, respectively. Using a human-shaped phantom, conversion factors between maximum entrance surface dose and DAP were derived for CA and CA plus PTCA, respectively. The dose to the staff was measured with TL dosimeters for 22 examinations. Fluoroscopy time and DAP were significantly (p=0.003) larger using the radial access route for coronary angiography (7.5 min, 51 Gy cm{sup 2}) than the corresponding values obtained from femoral access route (4.6 min, 38 Gy cm{sup 2}). For CA plus PTCA the fluoroscopy time and DAP were larger for radial access (18.4 min, 75 Gy cm{sup 2}) than for femoral access (12.5 min, 47 Gy cm{sup 2}; p=0.013). In our experience, radial access did significantly prolong the fluoroscopy time and increase the patient doses. (orig.)

  20. Determining effective methadone doses for individual opioid-dependent patients.

    Directory of Open Access Journals (Sweden)

    Jodie A Trafton

    2006-03-01

    Full Text Available BACKGROUND: Randomized clinical trials of methadone maintenance have found that on average high daily doses are more effective for reducing heroin use, and clinical practice guidelines recommend 60 mg/d as a minimum dosage. Nevertheless, many clinicians report that some patients can be stably maintained on lower methadone dosages to optimal effect, and clinic dosing practices vary substantially. Studies of individual responses to methadone treatment may be more easily translated into clinical practice. METHODS AND FINDINGS: A volunteer sample of 222 opioid-dependent US veterans initiating methadone treatment was prospectively observed over the year after treatment entry. In the 168 who achieved at least 1 mo of heroin abstinence, methadone dosages on which patients maintained heroin-free urine samples ranged from 1.5 mg to 191.2 mg (median = 69 mg. Among patients who achieved heroin abstinence, higher methadone dosages were predicted by having a diagnosis of posttraumatic stress disorder or depression, having a greater number of previous opioid detoxifications, living in a region with lower average heroin purity, attending a clinic where counselors discourage dosage reductions, and staying in treatment longer. These factors predicted 42% of the variance in dosage associated with heroin abstinence. CONCLUSIONS: Effective and ineffective methadone dosages overlap substantially. Dosing guidelines should focus more heavily on appropriate processes of dosage determination rather than solely specifying recommended dosages. To optimize therapy, methadone dosages must be titrated until heroin abstinence is achieved.

  1. Monte Carlo investigation of backscatter factors for skin dose determination in interventional neuroradiology procedures

    Science.gov (United States)

    Omar, Artur; Benmakhlouf, Hamza; Marteinsdottir, Maria; Bujila, Robert; Nowik, Patrik; Andreo, Pedro

    2014-03-01

    Complex interventional and diagnostic x-ray angiographic (XA) procedures may yield patient skin doses exceeding the threshold for radiation induced skin injuries. Skin dose is conventionally determined by converting the incident air kerma free-in-air into entrance surface air kerma, a process that requires the use of backscatter factors. Subsequently, the entrance surface air kerma is converted into skin kerma using mass energy-absorption coefficient ratios tissue-to-air, which for the photon energies used in XA is identical to the skin dose. The purpose of this work was to investigate how the cranial bone affects backscatter factors for the dosimetry of interventional neuroradiology procedures. The PENELOPE Monte Carlo system was used to calculate backscatter factors at the entrance surface of a spherical and a cubic water phantom that includes a cranial bone layer. The simulations were performed for different clinical x-ray spectra, field sizes, and thicknesses of the bone layer. The results show a reduction of up to 15% when a cranial bone layer is included in the simulations, compared with conventional backscatter factors calculated for a homogeneous water phantom. The reduction increases for thicker bone layers, softer incident beam qualities, and larger field sizes, indicating that, due to the increased photoelectric crosssection of cranial bone compared to water, the bone layer acts primarily as an absorber of low-energy photons. For neurointerventional radiology procedures, backscatter factors calculated at the entrance surface of a water phantom containing a cranial bone layer increase the accuracy of the skin dose determination.

  2. 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.

  3. 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.)

  4. Efficacy and immunogenicity of single-dose AdVAV intranasal anthrax vaccine compared to anthrax vaccine absorbed in an aerosolized spore rabbit challenge model.

    Science.gov (United States)

    Krishnan, Vyjayanthi; Andersen, Bo H; Shoemaker, Christine; Sivko, Gloria S; Tordoff, Kevin P; Stark, Gregory V; Zhang, Jianfeng; Feng, Tsungwei; Duchars, Matthew; Roberts, M Scot

    2015-04-01

    AdVAV is a replication-deficient adenovirus type 5-vectored vaccine expressing the 83-kDa protective antigen (PA83) from Bacillus anthracis that is being developed for the prevention of disease caused by inhalation of aerosolized B. anthracis spores. A noninferiority study comparing the efficacy of AdVAV to the currently licensed Anthrax Vaccine Absorbed (AVA; BioThrax) was performed in New Zealand White rabbits using postchallenge survival as the study endpoint (20% noninferiority margin for survival). Three groups of 32 rabbits were vaccinated with a single intranasal dose of AdVAV (7.5 × 10(7), 1.5 × 10(9), or 3.5 × 10(10) viral particles). Three additional groups of 32 animals received two doses of either intranasal AdVAV (3.5 × 10(10) viral particles) or intramuscular AVA (diluted 1:16 or 1:64) 28 days apart. The placebo group of 16 rabbits received a single intranasal dose of AdVAV formulation buffer. All animals were challenged via the inhalation route with a targeted dose of 200 times the 50% lethal dose (LD50) of aerosolized B. anthracis Ames spores 70 days after the initial vaccination and were followed for 3 weeks. PA83 immunogenicity was evaluated by validated toxin neutralizing antibody and serum anti-PA83 IgG enzyme-linked immunosorbent assays (ELISAs). All animals in the placebo cohort died from the challenge. Three of the four AdVAV dose cohorts tested, including two single-dose cohorts, achieved statistical noninferiority relative to the AVA comparator group, with survival rates between 97% and 100%. Vaccination with AdVAV also produced antibody titers with earlier onset and greater persistence than vaccination with AVA. PMID:25673303

  5. What Determines the Incidence and Extent of MgII Absorbing Gas Around Galaxies?

    CERN Document Server

    Chen, Hsiao-Wen; Tinker, Jeremy L; Gauthier, Jean-Rene; Helsby, Jennifer E; Shectman, Stephen A; Thompson, Ian B

    2010-01-01

    We study the connections between on-going star formation, galaxy mass, and extended halo gas, in order to distinguish between starburst-driven outflows and infalling clouds that produce the majority of observed MgII absorbers at large galactic radii (>~ 10 h^{-1} kpc) and to gain insights into halo gas contents around galaxies. We present new measurements of total stellar mass (M_star), H-alpha emission line strength (EW(H-alpha)), and specific star formation rate (sSFR) for the 94 galaxies published in H.-W. Chen et al. (2010). We find that the extent of MgII absorbing gas, R_MgII, scales with M_star and sSFR, following R_MgII \\propto M_star^{0.28}\\times sSFR^{0.11}. The strong dependence of R_MgII on M_star is most naturally explained, if more massive galaxies possess more extended halos of cool gas and the observed MgII absorbers arise in infalling clouds which will subsequently fuel star formation in the galaxies. The additional scaling relation of R_MgII with sSFR can be understood either as accounting f...

  6. 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

  7. Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the PTB, Germany and the BIPM in 60Co gamma radiation

    Science.gov (United States)

    Kessler, C.; Burns, D. T.; Kapsch, R.-P.; Krauss, A.

    2016-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Physikalisch-Technische Bundesanstalt, (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in October 2015. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the PTB and the BIPM standards for absorbed dose to water, is 0.9977 with a combined standard uncertainty of 3.8 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  8. 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)

  9. WE-A-17A-01: Absorbed Dose Rate-To-Water at the Surface of a Beta-Emitting Planar Ophthalmic Applicator with a Planar, Windowless Extrapolation Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Riley, A [of Wisconsin Medical Radiation Research Center, Madison, WI (United States); Soares, C [NIST (Retired), Gaithersburg, MD (United States); Micka, J; Culberson, W [University of Wisconsin Medical Radiation Research Center, Madison, WI (United States); DeWerd, L [University of WIMadison/ ADCL, Madison, WI (United States)

    2014-06-15

    Purpose: Currently there is no primary calibration standard for determining the absorbed dose rate-to-water at the surface of β-emitting concave ophthalmic applicators and plaques. Machining tolerances involved in the design of concave window extrapolation chambers are a limiting factor for development of such a standard. Use of a windowless extrapolation chamber avoids these window-machining tolerance issues. As a windowless extrapolation chamber has never been attempted, this work focuses on proof of principle measurements with a planar, windowless extrapolation chamber to verify the accuracy in comparison to initial calibration, which could be extended to the design of a hemispherical, windowless extrapolation chamber. Methods: The window of an extrapolation chamber defines the electrical field, aids in aligning the source parallel to the collector-guard assembly, and decreases the backscatter due to attenuation of lower electron energy. To create a uniform and parallel electric field in this research, the source was made common to the collector-guard assembly. A precise positioning protocol was designed to enhance the parallelism of the source and collector-guard assembly. Additionally, MCNP5 was used to determine a backscatter correction factor to apply to the calibration. With these issues addressed, the absorbed dose rate-to-water of a Tracerlab 90Sr planar ophthalmic applicator was determined using National Institute of Standards and Technology's (NIST) calibration formalism, and the results of five trials with this source were compared to measurements at NIST with a traditional extrapolation chamber. Results: The absorbed dose rate-to-water of the planar applicator was determined to be 0.473 Gy/s ±0.6%. Comparing these results to NIST's determination of 0.474 Gy/s yields a −0.6% difference. Conclusion: The feasibility of a planar, windowless extrapolation chamber has been demonstrated. A similar principle will be applied to developing a

  10. WE-A-17A-01: Absorbed Dose Rate-To-Water at the Surface of a Beta-Emitting Planar Ophthalmic Applicator with a Planar, Windowless Extrapolation Chamber

    International Nuclear Information System (INIS)

    Purpose: Currently there is no primary calibration standard for determining the absorbed dose rate-to-water at the surface of β-emitting concave ophthalmic applicators and plaques. Machining tolerances involved in the design of concave window extrapolation chambers are a limiting factor for development of such a standard. Use of a windowless extrapolation chamber avoids these window-machining tolerance issues. As a windowless extrapolation chamber has never been attempted, this work focuses on proof of principle measurements with a planar, windowless extrapolation chamber to verify the accuracy in comparison to initial calibration, which could be extended to the design of a hemispherical, windowless extrapolation chamber. Methods: The window of an extrapolation chamber defines the electrical field, aids in aligning the source parallel to the collector-guard assembly, and decreases the backscatter due to attenuation of lower electron energy. To create a uniform and parallel electric field in this research, the source was made common to the collector-guard assembly. A precise positioning protocol was designed to enhance the parallelism of the source and collector-guard assembly. Additionally, MCNP5 was used to determine a backscatter correction factor to apply to the calibration. With these issues addressed, the absorbed dose rate-to-water of a Tracerlab 90Sr planar ophthalmic applicator was determined using National Institute of Standards and Technology's (NIST) calibration formalism, and the results of five trials with this source were compared to measurements at NIST with a traditional extrapolation chamber. Results: The absorbed dose rate-to-water of the planar applicator was determined to be 0.473 Gy/s ±0.6%. Comparing these results to NIST's determination of 0.474 Gy/s yields a −0.6% difference. Conclusion: The feasibility of a planar, windowless extrapolation chamber has been demonstrated. A similar principle will be applied to developing a

  11. Review of personal monitoring techniques for the measurement of absorbed dose from external beta and low energy photon radiation

    DEFF Research Database (Denmark)

    Christensen, Poul

    1986-01-01

    The techniques available at present for personal monitoring of doses from external beta and low energy photon radiation are reviewed. The performance of currently used dosimetry systems is compared with that recommended internationally, and developments for improving the actual performance are...... materials and detector/filter geometry. Improvements in the energy and angular response of dosemeters for the measurements of doses from beta and low energy photon radiation can be achieved essentially through two different approaches: either by using thin detectors or multi-element dosemeters. Their...

  12. Effect of absorbed dose rate of ionizing radiation on decomposition of rare earth nitrates disposed in porous corundum foam

    International Nuclear Information System (INIS)

    The influence of irradiation with different dose rates on the process of rare earth nitrate (neodymium) decomposition on corundum foam was studied. By the method of thermal analysis it has been shown that irradiation decreases the temperature of decomposition of neodymium nitrate, while growth of the dose rate increases the depth of Nd(NO3)3·nH2O decomposition process(including denitration). The presence of x-phase of Al2O3 in the samples facilitates irreversible immobilization of fission products, decreasing considerably the temperature of matrix interaction with applied neodymium nitrate with formation of NdAlO3 phase. 5 refs., 3 figs

  13. Using thermoluminescence dosimetry (TLD) to determine the gonadal dose of patients under-going chest X-ray examinations at NKST hospital, Mkar

    International Nuclear Information System (INIS)

    The doses absorbed by the gonads of patients undergoing chest X-ray examinations at NKST Christian Hospital, Mkar was determined using the Thermoluminescence Dosimetry Technique of measurement. Also, the direct X-ray dose to the chest of patients undergoing the routine examinations was also determined using the Thermolumnescence Dosimetry technique of measurement. The mean gonadal dose and the X-ray dose to the patients were found to be 0.03±0.02μSv and 0.04±0.03mSv respectively after exposure. These X-ray doses to the patients is seen to be within the acceptable recommended X -ray dose limits of 1mGy recommended by ICRP.

  14. Ultraviolet absorbance titration for the determination of conditional stability constants of Hg(II) and dissolved organic matter

    Institute of Scientific and Technical Information of China (English)

    BAI Yingchen; WU Fengchang; WAN Guojiang; LIU Congqiang; FU Pingqing; LI Wen

    2008-01-01

    Strong interaction between natural dissolved organic matter (DOM) and Hg(II) may influence the transport, conversion, toxicity and bio-validity of mercury in the environment. In this paper ultraviolet (UV) absorbance titration was employed for the first time for the determination of the conditional stability constants of Hg(II) and (DOM). With increasing Hg(II) concentrations, the UV absorbance of fulvic acid, humic acid, and DOM in river increases progressively. By linear and non-linear model fitting, the conditional stability constants (lgK) of Hg(II) and DOM were worked out to be 3.54-4.93 and 3.64-4.85, respectively. The results are consistent with those acquired by the typical fluorescence quenching titration method, with the maximum relative error of lgK being 2.6% and the average relative error being 0.2%. The UV absorbance titration method has the advantages of rapid determination, simple performance, and it will probably become a new approach to studying interactions between DOM and trace metallic ions.

  15. DOSE TO CURIE DETERMINATION FOR CONTAINERS WITH MEASURABLE CS-137

    International Nuclear Information System (INIS)

    The Next Generation Retrieval (NGR) project will retrieve suspect transuranic (TRU) waste containers from Trenches 17 and 27 in the 218-E-12B (12B) burial ground. The trenches were in operation from May 1970 through October 1972. A portion of the retrieved containers that will require shipment to and acceptance at a treatment, storage, and disposal (TSD) facility and the containers will be either remote-handled (RH) and/or contact-handled (CH). The method discussed in this document will be used for the RH and some of the CH containers to determine the radionuclide inventory. Waste disposition (shipment and TSD acceptance) requires that the radioactive content be characterized for each container. Source-term estimates using high resolution, shielded, gamma-ray scan assay techniques cannot be performed on a number of RH and other containers with high dose rates from 137Cs-137mBa. This document provides the method to quantify the radioactive inventory of fission product gamma emitters within the containers based on the surface dose rate measurements taken in the field with hand-held survey instruments.

  16. Applicability of thermoluminescent dosimeters in X-ray organ dose determination and in the dosimetry of systemic and boron neutron capture radiotherapy

    International Nuclear Information System (INIS)

    The main detectors used for clinical dosimetry are ionisation chambers and semiconductors. Thermoluminescent (TL) dosimeters are also of interest because of their following advantages: (i) wide useful dose range, (ii) small physical size, (iii) no need for high voltage or cables, i.e. stand alone character, and (iv) tissue equivalence (LiF) for most radiation types. TL detectors can particularly be used for the absorbed dose measurements performed with the aim to investigate cases where dose prediction is difficult and not as part of a routine verification procedure. In this thesis, the applicability of TL detectors was studied in different clinical applications. Particularly, the major phenomena (e.g. energy dependence, sensitivity to high LET radiation, reproducibility) affecting on the precision and accuracy of TL detectors in the dose estimations were considered in this work. In organ dose determinations of diagnostic X-ray examinations, the TL detectors were found to be accurate within 5% (1 S.D.). For in viva studies using internal irradiation source, i.e. for systemic radiation therapy, a method for determining the absorbed doses to organs was introduced. The TL method developed was found to be able to estimate the absorbed doses to those critical organs near the body surface within 50%. In the mixed neutron-gamma field of boron neutron capture therapy (BNCT), TL detectors were used for gamma dose and neutron fluence measurements. They were found able to measure the neutron dose component with the accuracy of 16%, and therefore to be a useful addition to the activation foils in BNCT neutron dosimetry. The absorbed gamma doses can be measured with TL detectors within 20% in the mixed neutron-gamma field, which enables in viva measurements at BNCT beams with approximately the same accuracy. In this study, the uncertainties of TL dosimeters were found to be high but not essentially greater than those in other measurement techniques used for clinical dosimetry

  17. Determination of the integral dose in CT of the neurocranium

    International Nuclear Information System (INIS)

    The amount of exposure of the cranium is calculated on the basis of the measured dose distribution in craniocaudal direction and on the axial planes of the Alderson phantom. The integral dose of the cranium and the local dose at sensitive organs are used as a measure of radiation exposure. (orig.)

  18. 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

  19. 高能电子束不同吸收剂量测量方法的比较研究%Comparison of the absorbed dose measurement methods for high-energy electron beams

    Institute of Scientific and Technical Information of China (English)

    郭妍妍; 毕平; 李小东; 戴越

    2013-01-01

    目的 研究国际原子能机构(IAEA)第398号报告和第277号报告在电子线放射治疗剂量测定的差异.方法 采用圆柱型电离室、平行板电离室以及在用户高能电子线射线质下经过交叉校准的平行板电离室,分别依据两个报告,对医科达Precise加速器6档电子线在水中的吸收剂量进行精确测量.结果 用平行板电离室根据两个报告的测量规程测得的吸收剂量的差异为0.4%~2.3%,用圆柱型电离室测出的差异为0.6% ~2.2%,用经过交叉校准的平行板电离室测出的结果是0.5% ~2.0%.依据IAEA TRS-398和TRS-277报告的方法测得的吸收剂量具有较好的一致性.结论 IAEA TRS-398号报告关于电子线的校准方法较TRS-277号报告更精确,更加适用于临床用户进行测量.%Objective To study the difference in the measurement of the absorbed dose in water between the dosimetry protocols of IAEA TRS-398 and TRS-277 for high-energy electron beams.Methods The differences were compare in absorbed doses from 6 kinds of electron beams among the three methods of using cylindrical chamber,plane-parallel chamber and cross-calibrated plane-parallel chamber which was calibrated in user' s high-energy electron beam according to IAEA TRS-398 and IAEA TRS-277.Results The difference in absorbed doses measured,following the two protocols,was 0.4%-2.3% for planeparallel chamber,0.6%-2.2% for cylindrical chamber,and 0.5%-2.0% for cross-calibrated chamber.The differences in measured absorbed doses between the two dosimetry protocols were slight.Conclusions The methods used to determine absorbed dose to water recommanded by IAEA TRS-398 for high-energy beams are more accurate and more suitable for clinical users to measure compared to the TRS-277.

  20. 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)

  1. Super absorbent Prepared by Radiation Induced Graft Copolymerization of Acrylic Acid onto Cassava Starch

    International Nuclear Information System (INIS)

    Full text: Super absorbent was synthesized by radiation-induced graft polymerization of acrylic acid onto cassava starch. Parameters such as the absorbed dose and the amount of monomer were investigated in order to determine the optimum conditions for the grafting polymerization. Water retention, germination percentage and germination energy were determined in order to evaluate the possibility of super absorbent in agricultural applications, especially in arid regions. The graft copolymer was characterized by FTIR. Results indicated that the sand mixed with 0.1%wt super absorbent can absorb more water than the sand without super absorbent. The germination energy of corn seeds mixed with 0.5% super absorbent was obviously higher than those without super absorbent. These experimental results showed that the super absorbent has considerable effect on seed germination and the growth of young plants. Keywords: Super absorbent, Radiation, Acrylic acid, Cassava starch

  2. Reconstruction of the absorbed external doses to the population living in areas of the Russian Federation contaminated as a result of the Chernobyl accident

    International Nuclear Information System (INIS)

    For epidemiological studies aimed at understanding how the radiation factor affected the people living in the areas contaminated following the Chernobyl accident, knowledge is required of radiation loads for human organs and tissues from external and internal exposure. In this respect of great importance are data about absorbed doses received in the first year after the accident. Methods and assessments available in the literature are based on a simple approximation of one time entrance of radionuclides into the environment. Space-time characteristics of depositions have been reconstructed with varying accuracy, primarily for 137Cs and 131I. Therefore, now 8 years after the accident, it seems important to reconstruct the complete dynamic picture of the radioactive contamination of the Russian Federation with consideration of newly published data about the source term. 5 refs, 1 fig, 1 tab

  3. Automation of the monitoring in real time of the absorbed dose rate in air due to the environmental gamma radiation in Cuba

    International Nuclear Information System (INIS)

    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)

  4. Determination of Superficial Dose Profile in Z-Line for Each Slice in CT.Scan Machines

    Directory of Open Access Journals (Sweden)

    V Changizi

    2004-10-01

    Full Text Available CT.Scan examinations cause high patient absorbed dose from x-ray ionizing radiation. Therefore it is necessary to obtain superficial dose profile in Z-line. In this research 11 thermoluminecent dosimeter (TLD, after calibration were located on Z line perpendicular to slice thickness. CT.Scan machines did X-ray exposures. The resultant dose profiles showed gussian shape apperience, which has severed dose reduction off the slice thickness. By attention to high patient absorbed dose in CT.Scan machines, it is better to referre that patients towards any other diagnostic methods with lower risk and reasonable quality.

  5. Determination of the optimum irradiation dose for shelf-life of peas and cherry tomatoes

    International Nuclear Information System (INIS)

    Green peas (Pisum Sativum), cultivar (mangetout) and yellow cherry tomatoes (lycoperscum esculantum), cultivar (cerasiforme) were irradiated for different absorbed doses, and their physical characteristics observed under cold storage conditions, in order to extend their shelf lives. Results suggest that 580 Gy is the maximum optimum dose. At this dose the shelf life of cherry tomatoes is shown to be extended. No beneficial effect was recorded on the storage life of green peas. A good correlation was found between the degradation of chlorophill and the spread of spotting disease for this product. (author)., 19 refs., 2 tab

  6. 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

  7. Determination of the optimal minimum radioiodine dose in patients with Graves' disease: a clinical outcome study

    Energy Technology Data Exchange (ETDEWEB)

    Howarth, D.; Tan, P.; Booker, J. [Pacific Medical Imaging, Newcastle, NSW (Australia); Epstein, M. [Dept. of Endocrinology, John Hunter Hospital, Newcastle, NSW (Australia); Lan, L. [High-Dependency Unit, St. George Hospital, Sydney, NSW (Australia)

    2001-10-01

    The study was performed under the auspices of the International Atomic Energy Commission, Vienna, Austria, with the aim of determining the optimal minimum therapeutic dose of iodine-131 for Graves' disease. The study was designed as a single-blinded randomised prospective outcome trial. Fifty-eight patients were enrolled, consisting of 50 females and 8 males aged from 17 to 75 years. Each patient was investigated by clinical assessment, biochemical and immunological assessment, thyroid ultrasound, technetium-99m thyroid scintigraphy and 24-h thyroid {sup 131}I uptake. Patients were then randomised into two treatment groups, one receiving 60 Gy and the other receiving 90 Gy thyroid tissue absorbed dose of radioiodine. The end-point markers were clinical and biochemical response to treatment. The median follow-up period was 37.5 months (range, 24-48 months). Among the 57 patients who completed final follow-up, a euthyroid state was achieved in 26 patients (46%), 27 patients (47%) were rendered hypothyroid and four patients (7%) remained hyperthyroid. Thirty-four patients (60%) remained hyperthyroid at 6 months after the initial radioiodine dose (median dose 126 MBq), and a total of 21 patients required additional radioiodine therapy (median total dose 640 MBq; range 370-1,485 MBq). At 6-month follow-up, of the 29 patients who received a thyroid tissue dose of 90 Gy, 17 (59%) remained hyperthyroid. By comparison, of the 28 patients who received a thyroid tissue dose of 60 Gy, 17 (61%) remained hyperthyroid. No significant difference in treatment response was found (P=0.881). At 6 months, five patients in the 90-Gy group were hypothyroid, compared to two patients in the 60-Gy group (P=0.246). Overall at 6 months, non-responders to low-dose therapy had a significantly larger thyroid gland mass (respective means: 35.9 ml vs 21.9 ml) and significantly higher levels of serum thyroglobulin (respective means: 597.6 {mu}g/l vs 96.9 {mu}g/l). Where low-dose radioiodine

  8. Development of a diamond dosimeter for measuring the absorbed dose in small beams used in stereotactic radiotherapy

    International Nuclear Information System (INIS)

    Stereotactic radiotherapy is a relatively recent technique used for the treatment of small benign and malignant tumors with small radiation beams. The clinical efficiency of this technique has been proved. However, the measurement of absolute and relative dose in small beams is not possible currently due to the lack of suited detectors for these measurements. In small beam dosimetry, the detector has to be as close as possible to tissue equivalence and exhibit a small detection volume due to the lack of lateral electronic equilibrium. Characteristics of diamond (water equivalent material Z=6, high density) make it an ideal candidate to fulfil most of small beam dosimetry requirements. In this thesis, we developed a dosimeter prototype for small beams, based on CVD synthetic single crystal diamond. The diamond samples were characterized optically and their detection properties were investigated under X-rays and alpha-particles. First diamond dosimeter prototypes were tested with small beams produced by several stereotactic machines. Studies using Monte Carlo simulations were performed in order to optimize the parameters involved in the detector response in small beams. This leaded to a final diamond dosimeter prototype that respects all radiotherapy centers requirements, in both standard and small beams. (author)

  9. The use of solar cells for continuous recording of absorbed dose in the product during radiation sterilization

    International Nuclear Information System (INIS)

    As a result of the rapidly developing space programme, reliable solar panels were needed as an energy source for space capsules. It was found that when a space capsule passed through the Van Allen Belt, the solar panels aged owing to the radiation, and the energy output declined. The United States National Aeronautics and Space Administration investigated the pre-irradiation of solar panels and found that they withstood high doses, such as 20 Mrad, the panels having aged and the energy output having become lower but steady. The response of the solar cells to high levels of radiation caused Gammaster to attempt to use this effect to serve as a check on the operating status of its large 60Co gamma irradiation facility. During γ-irradiation a potential is generated in a p-n silicon solar cell which can be made to drive ancillary equipment. For example, the current from the solar cell can be fed to a pen recorder to assist in process control. The pen recorder can, for example, also act as an automatic logbook by recording the irradiation times. The sensitivity of a cell is such that changes in absorption between homogeneously and inhomogeneously filled containers are clearly shown on the recorder sheets. All source movements are visible, and the timer setting and the number of containers treated, etc. can be monitored. Such a system provides a reliable additional process control at low cost and requests little maintenance. (author)

  10. 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.

  11. Dose determination in breast tumor in brachytherapy using Iridium-192

    International Nuclear Information System (INIS)

    Thermoluminescent dosimetry studies in vivo and in vitro aiming to determing radiation dose in the breast tumor, in brachytherapy using Iridium-192 was done. The correlation between radiation doses in tumor and external surface of the breast was investigated for correcting the time interval of radiation source implantation. (author)

  12. 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)

  13. Determination of water-insoluble light absorbing matter in rainwater using polycarbonate membrane filters and photometric detection

    Directory of Open Access Journals (Sweden)

    J. E. Engström

    2009-02-01

    Full Text Available A method for determination of water-insoluble light absorbing matter in rainwater has been developed. After collection the rainwater samples were filtered using polycarbonate membrane filter in the laboratory. After drying the filter in filtered air, the amount of water-insoluble light absorbing matter (soot on the filters was determined with photometry at a wavelength of 555 nm. The precision for the method was better than 10% calculated as relative standard deviation. The overall loss of soot due to adsorption during collection and filtration was 22±2%. The detection limit was estimated to 0.025 in optical density, or 2 ng/ml expressed as a concentration assuming a filtration volume of 30 ml. Analysis of environmental samples have been successfully performed with the described method at the Maldives Climate Observatory Hanimaadhoo and Nepal Climate Observatory. At Maldives the average soot concentration in rain was 0.048 μg/ml and at the Nepal obseravtory 0.086 μg/ml.

  14. 10 CFR 20.1203 - Determination of external dose from airborne radioactive material.

    Science.gov (United States)

    2010-01-01

    ... RADIATION Occupational Dose Limits § 20.1203 Determination of external dose from airborne radioactive... equivalent to an individual should be based upon measurements using instruments or individual monitoring... 10 Energy 1 2010-01-01 2010-01-01 false Determination of external dose from airborne...

  15. 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

  16. Establishment of a γ-H2AX foci-based assay to determine biological dose of radon to red bone marrow in rats

    Science.gov (United States)

    Wang, Jing; He, Linfeng; Fan, Dunhuang; Ding, Defang; Wang, Xufei; Gao, Yun; Zhang, Xuxia; Li, Qiang; Chen, Honghong

    2016-07-01

    The biodosimetric information is critical for assessment of cancer risk in populations exposed to high radon. However, no tools are available for biological dose estimation following radon exposure. Here, we established a γ-H2AX foci-based assay to determine biological dose to red bone marrow (RBM) in radon-inhaled rats. After 1–3 h of in vitro radon exposure, a specific pattern of γ-H2AX foci, linear tracks with individual p-ATM and p-DNA-PKcs foci, was observed, and the yield of γ-H2AX foci and its linear tracks displayed a linear dose-response manner in both rat peripheral blood lymphocytes (PBLs) and bone-marrow lymphocytes (BMLs). When the cumulative doses of radon inhaled by rats reached 14, 30 and 60 working level months (WLM), the yields of three types of foci markedly increased in both PBLs and BMLs, and γ-H2AX foci-based dose estimates to RBM were 0.97, 2.06 and 3.94 mGy, respectively. Notably, BMLs displayed a more profound increase of three types of foci than PBLs, and the absorbed dose ratio between BMLs and PBLs was similar between rats exposed to 30 and 60 WLM of radon. Taken together, γ-H2AX foci quantitation in PBLs is able to estimate RBM-absorbed doses with the dose-response curve of γ-H2AX foci after in vitro radon exposure and the ratio of RBM- to PBL-absorbed doses in rats following radon exposure.

  17. Establishment of a γ-H2AX foci-based assay to determine biological dose of radon to red bone marrow in rats

    Science.gov (United States)

    Wang, Jing; He, Linfeng; Fan, Dunhuang; Ding, Defang; Wang, Xufei; Gao, Yun; Zhang, Xuxia; Li, Qiang; Chen, Honghong

    2016-01-01

    The biodosimetric information is critical for assessment of cancer risk in populations exposed to high radon. However, no tools are available for biological dose estimation following radon exposure. Here, we established a γ-H2AX foci-based assay to determine biological dose to red bone marrow (RBM) in radon-inhaled rats. After 1–3 h of in vitro radon exposure, a specific pattern of γ-H2AX foci, linear tracks with individual p-ATM and p-DNA-PKcs foci, was observed, and the yield of γ-H2AX foci and its linear tracks displayed a linear dose-response manner in both rat peripheral blood lymphocytes (PBLs) and bone-marrow lymphocytes (BMLs). When the cumulative doses of radon inhaled by rats reached 14, 30 and 60 working level months (WLM), the yields of three types of foci markedly increased in both PBLs and BMLs, and γ-H2AX foci-based dose estimates to RBM were 0.97, 2.06 and 3.94 mGy, respectively. Notably, BMLs displayed a more profound increase of three types of foci than PBLs, and the absorbed dose ratio between BMLs and PBLs was similar between rats exposed to 30 and 60 WLM of radon. Taken together, γ-H2AX foci quantitation in PBLs is able to estimate RBM-absorbed doses with the dose-response curve of γ-H2AX foci after in vitro radon exposure and the ratio of RBM- to PBL-absorbed doses in rats following radon exposure. PMID:27445126

  18. Establishment of a γ-H2AX foci-based assay to determine biological dose of radon to red bone marrow in rats.

    Science.gov (United States)

    Wang, Jing; He, Linfeng; Fan, Dunhuang; Ding, Defang; Wang, Xufei; Gao, Yun; Zhang, Xuxia; Li, Qiang; Chen, Honghong

    2016-01-01

    The biodosimetric information is critical for assessment of cancer risk in populations exposed to high radon. However, no tools are available for biological dose estimation following radon exposure. Here, we established a γ-H2AX foci-based assay to determine biological dose to red bone marrow (RBM) in radon-inhaled rats. After 1-3 h of in vitro radon exposure, a specific pattern of γ-H2AX foci, linear tracks with individual p-ATM and p-DNA-PKcs foci, was observed, and the yield of γ-H2AX foci and its linear tracks displayed a linear dose-response manner in both rat peripheral blood lymphocytes (PBLs) and bone-marrow lymphocytes (BMLs). When the cumulative doses of radon inhaled by rats reached 14, 30 and 60 working level months (WLM), the yields of three types of foci markedly increased in both PBLs and BMLs, and γ-H2AX foci-based dose estimates to RBM were 0.97, 2.06 and 3.94 mGy, respectively. Notably, BMLs displayed a more profound increase of three types of foci than PBLs, and the absorbed dose ratio between BMLs and PBLs was similar between rats exposed to 30 and 60 WLM of radon. Taken together, γ-H2AX foci quantitation in PBLs is able to estimate RBM-absorbed doses with the dose-response curve of γ-H2AX foci after in vitro radon exposure and the ratio of RBM- to PBL-absorbed doses in rats following radon exposure. PMID:27445126

  19. Conversion coefficients for determining organ doses in paediatric spine radiography

    Energy Technology Data Exchange (ETDEWEB)

    Seidenbusch, Michael; Schneider, Karl [Ludwig-Maximilians-University of Munich, Institute of Clinical Radiology - Paediatric Radiology, Muenchen (Germany)

    2014-04-15

    Knowledge of organ and effective doses achieved during paediatric x-ray examinations is an important prerequisite for assessment of radiation burden to the patient. Conversion coefficients for reconstruction of organ and effective doses from entrance doses for segmental spine radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients are provided regarding the Guidelines of Good Radiographic Technique of the European Commission. Using the personal computer program PCXMC developed by the Finnish Centre for Radiation and Nuclear Safety (Saeteilyturvakeskus STUK), conversion coefficients for conventional segmental spine radiographs were calculated performing Monte Carlo simulations in mathematical hermaphrodite phantom models describing patients of different ages. The clinical variation of beam collimation was taken into consideration by defining optimal and suboptimal radiation field settings. Conversion coefficients for the reconstruction of organ doses in about 40 organs and tissues from measured entrance doses during cervical, thoracic and lumbar spine radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients were calculated for the standard sagittal and lateral beam projections and the standard focus detector distance of 115 cm. The conversion coefficients presented may be used for organ dose assessments from entrance doses measured during spine radiographs of patients of all age groups and all field settings within the optimal and suboptimal standard field settings. (orig.)

  20. Comparative evaluation of changes in the absorbed doses of neutron radiation and chromosome aberration frequency in human blood lymphocytes by a water phantom depth during irradiation with a medico-biological beam at the BR-10 reactor

    International Nuclear Information System (INIS)

    Distribution of the chromosome aberration frequency in human blood lymphocyte samples and absorbed doses have been compared by the water phantom depth during irradiation with 1.5 Gy neutrons (mean energy of 0.85 MeV). There is a good concordance of their depth distribution. The half-fall layer of the absorbed dose within the tissue-equivalent medium is similar (∼ 5 cm) with both measurements done. The aberration frequency in the biological samples placed outside the radiation field in the phantom increases which indicates that the neutron beem bounds are indistinct upon passing the tissue-equivalent medium

  1. Natural dose level determination at Johor State with thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    This paperwork presented the results of using thermoluminescence dosimetry (TLD) method in measuring background dose level, which is done at State of Johor, South Malaysia. The problems faced also discussed

  2. Dosimetrically determined doses of radioiodine for the treatment of metastatic thyroid carcinoma.

    Science.gov (United States)

    Van Nostrand, Douglas; Atkins, Frank; Yeganeh, Fred; Acio, Elmo; Bursaw, Randy; Wartofsky, Leonard

    2002-02-01

    In the absence of definitive studies relating radioiodine dose to outcomes, selection of a dose of radioiodine to treat metastatic thyroid carcinoma is problematic, and several approaches have been used. These include empiric fixed doses and doses used on dosimetric approaches specific for each patient. This paper is a review of the rationale and technique for dosimetrically-determined doses of radioiodine for the treatment of metastatic thyroid carcinoma. This review (1) discusses the alternatives for selection of a dose, (2) discusses the two major approaches for determining radioiodine doses dosimetrically, (3) briefly reviews several modifications of these approaches, (4) reviews the literature regarding the results, (5) discusses the side effects of these different approaches, and (6) concludes with recommendations for patient management and future research. This review does not address use of dosimetrically-determined doses of radioiodine for the initial ablation of thyroid tissue postoperatively.

  3. Determining organ doses from computed tomography scanners using cadaveric subjects

    Science.gov (United States)

    Griglock, Thomas M.

    The use of computed tomographic (CT) imaging has increased greatly since its inception in 1972. Technological advances have increased both the applicability of CT exams for common health problems as well as the radiation doses used to perform these exams. The increased radiation exposures have garnered much attention in the media and government agencies, and have brought about numerous attempts to quantify the amount of radiation received by patients. While the overwhelming majority of these attempts have focused on creating models of the human body (physical or computational), this research project sought to directly measure the radiation inside an actual human being. Three female cadaveric subjects of varying sizes were used to represent live patients. Optically-stimulated luminescent (OSL) dosimeters were used to measure the radiation doses. A dosimeter placement system was developed, tested, and optimized to allow accurate and reproducible placement of the dosimeters within the cadaveric subjects. A broad-beam, 320-slice, volumetric CT scanner was utilized to perform all CT exams, including five torso exams, four cardiac exams, and three organ perfusion exams. Organ doses ranged in magnitude from less than 1 to over 120 mGy, with the largest doses measured for perfusion imaging. A methodology has been developed that allows fast and accurate measurement of actual organ doses resulting from CT exams. The measurements made with this methodology represent the first time CT organ doses have been directly measured within a human body. These measurements are of great importance because they allow comparison to the doses measured using previous methods, and can be used to more accurately assess the risks from CT imaging.

  4. 辐照包装箱吸收剂量的检测方法及剂量计的评价%METHODS TO VERIFY ABSORBED DOSE OF IRRADIATED ORANGE CONTAINERS AND EVALUATION OF DOSIMETERS

    Institute of Scientific and Technical Information of China (English)

    高美须; 王传耀; 唐掌雄; 李淑荣

    1998-01-01

    The research on dose distribution on irradiated food containers and evaluation of several methods to verify absorbed dose were carried out. The minimum absorbed dose of treated five orange containers was in the top of the highest or in the bottom of lowest container in a commercial 60Co facility.Dmax/Dmin in this study was 1.45 . The density of orange containers was 0.391g/cm3. The evaluation of dosimeters showed that the PMMA-YL and clear PMMA dosimeters have line relationship with dose response, and the word NOT in STERIN-125 and STERIN-300 indicators were covered completely at the dosage of 125 and 300 Gy, respectively.

  5. Determination of dose rates from natural radionuclides in dental materials

    International Nuclear Information System (INIS)

    Different types of materials used for dental prosthetics restoration, including feldspathic ceramics, glass ceramics, zirconia-based ceramics, alumina-based ceramics, and resin-based materials, were investigated with regard to content of natural radionuclides by means of thermoluminescence beta dosimetry and gamma spectrometry. The gross beta dose rate from feldspathic and glass ceramics was about ten times higher than the background measurement, whereas resin-based materials generated negligible beta dose rate, similarly to natural tooth samples. The specific activity of uranium and thorium was significantly below the levels found in the period when addition of uranium to dental porcelain materials was still permitted. The high-beta dose levels observed in feldspathic porcelains and glass ceramics are thus mainly ascribable to 4K, naturally present in these specimens. Although the measured values are below the recommended limits, results indicate that patients with prostheses are subject to higher dose levels than other members of the population. Alumina- and zirconia-based ceramics might be a promising alternative, as they have generally lower beta dose rates than the conventional porcelain materials. However, the dosimetry results, which imply the presence of inhomogeneously distributed clusters of radionuclides in the sample matrix, and the still unsuitable structural properties call for further optimization of these materials

  6. Determination of aggregation thresholds of UV absorbing anionic surfactants by frontal analysis continuous capillary electrophoresis.

    Science.gov (United States)

    Le Saux, Thomas; Varenne, Anne; Gareil, Pierre

    2004-06-01

    Aggregation of anionic surfactants was investigated by frontal analysis continuous capillary electrophoresis (FACCE), a method involving the continuous electrokinetic introduction of the surfactant sample into the separation capillary. This process results in a partial separation of the monomeric and aggregated forms without perturbing the monomer-aggregate equilibrium. The critical micelle concentration (CMC) can then be easily derived from the height of the firstly detected migration front, corresponding to the monomeric form. This approach is exemplified with octyl and dodecylbenzenesulfonates and compared with conductimetry and surface tension measurements. FACCE turns out to be an effective method for the determination of CMC and intermediate aggregation phenomena with very small sample and short time requirements.

  7. Modernisation of a test rig for determination of vehicle shock absorber characteristics by considering vehicle suspension elements and unsprung masses

    Science.gov (United States)

    Maniowski, M.; Para, S.; Knapczyk, M.

    2016-09-01

    This paper presents a modernization approach of a standard test bench for determination of damping characteristics of automotive shock absorbers. It is known that the real-life work conditions of wheel-suspension dampers are not easy to reproduce in laboratory conditions, for example considering a high frequency damper response or a noise emission. The proposed test bench consists of many elements from a real vehicle suspension. Namely, an original tyre-wheel with additional unsprung mass, a suspension spring, an elastic top mount, damper bushings and a simplified wheel guiding mechanism. Each component was tested separately in order to identify its mechanical characteristics. The measured data serve as input parameters for a numerical simulation of the test bench behaviour by using a vibratory model with 3 degrees of freedom. Study on the simulation results and the measurements are needed for further development of the proposed test bench.

  8. 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)

  9. Brain-Cocaine Concentrations Determine the Dose Self-Administered by Rats on a Novel Behaviorally Dependent Dosing Schedule

    Science.gov (United States)

    Zimmer, Benjamin A; Dobrin, Carson V; Roberts, David C S

    2011-01-01

    A novel behaviorally dependent dosing (BDD) schedule was used to examine the relationship between doses of cocaine self-administered by rats and brain drug levels within a session. The BDD schedule used a hold-down response to activate a syringe pump. The length of time the lever was held down determined the duration that the syringe pump was activated. In the first experiment, rats self-administered cocaine for daily 3 h sessions and brain levels of cocaine were modeled using well-established parameters. Although analysis revealed that rats self-administered doses within a predicted range, one extremely large dose was consistently observed at the beginning of each session when brain levels of cocaine were low. In the second experiment, we introduced a range of timeout periods (10–25 min) in order to produce variability in brain-cocaine concentrations. Animals self-administered larger doses immediately following each timeout period and the dose size was inversely correlated with the length of the timeout. These results show that the dose of cocaine that rats self-administer within a session is inversely related to the amount of drug on board. PMID:21849981

  10. Determination of effective bremsstrahlung spectra and electron contamination for photon dose calculations

    International Nuclear Information System (INIS)

    A method is described for determining an effective, depth dose consistent bremsstrahlung spectra for high-energy photon beams using depth dose curves measured in water. A simple, analytical model with three parameters, together with the nominal accelerating potential is used to characterise the bremsstrahlung spectra. The model is used to compute weights for depth dose curves from monoenergetic photons. These monoenergetic depth doses, calculated with the convolution method from Monte Carlo generated point spread functions (PSF), are added to yield the pure photon depth dose distribution. The parameters of the analytical spectrum model are determined using an iterative technique to minimise the difference between calculated and measured depth dose curves. The influence from contaminant electrons is determined from the difference between the calculated and the measured depth dose. (author)

  11. 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.

  12. Determination of dose equivalent and risk in thorium cycle

    International Nuclear Information System (INIS)

    In these report are presented the calculations of dose equivalent and risk, utilizing the dosimetric model described in publication 30 of the International Comission on Radiological Protection. This information was obtained by the workers of the thorium cycle, employed at the Praia and Santo Amaro Facilities, by assessing the quantity and concentration of thorium in the air. The samples and the number of measurements were established through design of experiments techniques, and the results were evaluated with the aid of variance analysis. The estimater of dose equivalent for internal and external radiation exposure and risk associated were compared with the maximum recommended limits. The results indicate the existence of operation areas whose values were above those limits, requiring so an improvement in the procedures and services in order to meet the requirements of the radiological protetion. (author)

  13. Determination of Appropriate Dosing of Influenza Drugs in Pediatric Patients

    OpenAIRE

    Acosta, EP; Kimberlin, DW

    2010-01-01

    Dose-finding studies of influenza antiviral drugs are challenging because it is difficult to enroll subjects in pediatric interventional studies and also because of the lack of concentration (or toxicity)–response relationships, the short duration of antiviral therapy, and the continually developing metabolic profiles of infants and young children. The evaluation of influenza antiviral agents in premature infants adds even more complexity. Recent advances in exposure-targeted study designs an...

  14. Determination of tetracycline dose in treatment of advanced periodontitis

    Directory of Open Access Journals (Sweden)

    Tabatabaei E.

    1999-07-01

    Full Text Available This study is for appointment the dose of systemic 4 groups of patients selected for this study."nFirst group had sealling, root planing and planing and periodontal surgery and no drugs. Second group"nhad sealling, root planing and periodontal surgery with 1 gr per day of tetracycline for two weeks and"nthird group for 3 weeks and fourth group for 4 weeks."nThe fourth group was.the best clinical improvement. The indexes were PPD, CAL, PI, GI.

  15. Determination of skin dose reduction by lead equivalent gloves

    International Nuclear Information System (INIS)

    Radiation protective gloves are always used in medical facilities to protect radiation workers from unnecessary radiation exposure. A study on radiation protection gloves which are produced by local company had been performed by the Medical Physics Group, MINT. The gloves were made of lead equivalent material, as the attenuating element. The gloves were evaluated in term of the percentage of skin dose reduction by using a newly developed procedure and facilities in MINT. Attenuation measurements of the gloves had been carried out using direct beams and scattered radiations of different qualities. TLD rings were fitted on finger phantom; and water phantom were used in the measurement. The result were obtained and analysed based on data supplied by manufacturer. (Author)

  16. Subtle variations in Pten dose determine cancer susceptibility.

    Science.gov (United States)

    Alimonti, Andrea; Carracedo, Arkaitz; Clohessy, John G; Trotman, Lloyd C; Nardella, Caterina; Egia, Ainara; Salmena, Leonardo; Sampieri, Katia; Haveman, William J; Brogi, Edi; Richardson, Andrea L; Zhang, Jiangwen; Pandolfi, Pier Paolo

    2010-05-01

    Cancer susceptibility has been attributed to at least one heterozygous genetic alteration in a tumor suppressor gene (TSG). It has been hypothesized that subtle variations in TSG expression can promote cancer development. However, this hypothesis has not yet been definitively supported in vivo. Pten is a TSG frequently lost in human cancer and mutated in inherited cancer-predisposition syndromes. Here we analyze Pten hypermorphic mice (Pten(hy/+)), expressing 80% normal levels of Pten. Pten(hy/+) mice develop a spectrum of tumors, with breast tumors occurring at the highest penetrance. All breast tumors analyzed here retained two intact copies of Pten and maintained Pten levels above heterozygosity. Notably, subtle downregulation of Pten altered the steady-state biology of the mammary tissues and the expression profiles of genes involved in cancer cell proliferation. We present an alterative working model for cancer development in which subtle reductions in the dose of TSGs predispose to tumorigenesis in a tissue-specific manner.

  17. TLD determination of neutron dose contribution in medical linac

    International Nuclear Information System (INIS)

    The increased use of Linacs with accelerating voltage higher than 10 MV in clinical radiotherapy is producing and increasing demand of accurate dosimetric measurements of the photon induced neutron contamination of the radiotherapy beams, due that the associated Bremsstrahlung X rays may produce neutrons as a result of subsequent photonuclear reactions with the different materials constituting the accelerator head. Thermal neutron fluences can be measured with TLD-600/TLD-700 pairs arranged in both a bare and a cadmium (Cd) foil covered methacry-late box. Neutron response of Tl dosemeters irradiated with two different neutron sources has been investigated. The shape of the glow curve of these TLDs after irradiation in a medical Linac and in a Pu Be neutron source has been studied to verify the contribution of neutrons to an additional dose to staff, patients and the general public, due to photonuclear reactions generating neutrons from medical Linacs. (Author)

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

    OpenAIRE

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

    2014-01-01

    International audience Samples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO 3 and NaNO 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 s...

  19. A METHOD OF DETERMINING THE ABILITY OF THE ARRESTER TO ABSORB ENERGY WITHOUT BREAKING THE HEAT BALANCE

    Directory of Open Access Journals (Sweden)

    S.Yu. Shevchenko

    2015-08-01

    Full Text Available Purpose.The aim of this study is to obtain a method for determining the capacity surge arrester nonlinear absorb energy without breaking the heat balance in modes of long-term application of operating voltage, which allows for analysis of their work in terms of violations as electricity. Methodology. For values of the energy passing through the arrester must be able to determine the current value for the voltage value in the area of leakage current-voltage characteristics. We have carried out calculations of the energy passing everywhere arrester for certain periods of time based on the current-voltage characteristics obtained experimentally. Analysis of the experimental current-voltage characteristics of resistors and literature led to the important conclusion that the dielectric properties of the ceramic varistor affect the value of active power losses in the arrester only when the active component of the leakage current is very small. This is confirmed by the characteristics of different classes of varistor voltage. This property of varistors and surge arresters shows the need to consider how the dielectric and conductive properties of the varistor ceramics in the analysis of work in the area of the arrester leakage current-voltage characteristic. These results demonstrate the need to clarify the mathematical model and the method for determining the energy dissipates in the area of the arrester leakage current CVC with their account. Results. The study, an improved mathematical model for calculating energy affects surge arrester during its working life. The study obtained the method, of evaluation capacity surge arrester, maintains heat balance throughout working life. Based on experimentally obtained current-voltage characteristic of the varistors is defined voltage at which surge arrester starts conducting active current. This allowed to receive specified mathematical model for calculating energy affects surge arrester and develop a method

  20. Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    LIU,Yan; XU,Jin-Zhong; DING,Tao; LI,Gong-Hai

    2007-01-01

    A determination method has been optimized and validated for the simultaneous analysis of tetracycline (TC),oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DC) in honey. Tetracyclines (TCs) were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction (SPE), while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile,and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 μg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% (n= 18). Detection limits of 5,5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey (2-50 ng/g) was realized by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r>0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey.

  1. Subtle variations in Pten dose determine cancer susceptibility

    Science.gov (United States)

    Alimonti, Andrea; Carracedo, Arkaitz; Clohessy, John G; Trotman, Lloyd C; Nardella, Caterina; Egia, Ainara; Salmena, Leonardo; Sampieri, Katia; Haveman, William J; Brogi, Edi; Richardson, Andrea L; Zhang, Jiangwen; Pandolfi, Pier Paolo

    2010-01-01

    Cancer susceptibility has been attributed to at least one heterozygous genetic alteration in a tumor suppressor gene (TSG)1. It has been hypothesized that subtle variations in TSG expression can promote cancer development2,3. However, this hypothesis has not yet been definitively supported in vivo. PTEN is a TSG frequently lost in human cancer and mutated in inherited cancer-predisposition syndromes4. Here, we analyze Pten hypermorphic mice (Ptenhy/+), expressing 80% normal levels of Pten. Ptenhy/+ mice develop a spectrum of tumors, with breast tumors occurring at the highest penetrance. All breast tumors analyzed here retained two intact copies of Pten and maintained Pten levels above heterozygosis. Notably, subtle downregulation of Pten altered the steady-state biology of the mammary tissues and the expression profiles of genes involved in cancer cell proliferation. We present an alterative working model for cancer development in which subtle reductions in the dose of TSGs predispose to tumorigenesis in a tissue-specific manner. PMID:20400965

  2. The 90Sr +90Y kinetics investigation exchange and absorbed doses formation after acute internal irradiation of the rats in model experiment

    International Nuclear Information System (INIS)

    The possibility of the camera model theory application for the description of metabolic processes in the living organisms has been analyzed. The type of transport matrix of the model has been determined according to physical and biological limits for the system. It has been shown that camera model is stable. It is able to describe uniquely the processes in the living organisms. Model of 10 cameral has been proposed in order to describe 90Sr + 90Y exchange in the laboratory rats organism. The functions of isotope retention and kinetic constants needed for the practical application of the camera model theory have been determined for each camera. The doses of exposure of the experimental animals' organs ant tissues have been calculated

  3. Determination of γ-hydroxybutyric acid in saliva by capillary electrophoresis coupled with contactless conductivity and indirect UV absorbance detectors.

    Science.gov (United States)

    Mazina, Jekaterina; Saar-Reismaa, Piret; Kulp, Maria; Kaljurand, Mihkel; Vaher, Merike

    2015-12-01

    The aim of the current study was to optimise and validate the methodology for determination of γ-hydroxybutyric acid (GHB) in saliva by CE combined with a contactless conductivity detector (C(4)D) and indirect UV absorbance detection (λ(ABS) = 210 nm). The optimized BGE, consisting of 8.5 mM maleic acid, 17 mM arginine, 255 μM cetyltrimethylammonium bromide (CTAB), and 15% acetonitrile, was evaluated for the separation of GHB in saliva within 6 min. The performance characteristics of the CE-C(4)D-indirect UV methodology was validated. The instrument detection and quantification limits were 0.49 and 1.6 mg/L for C(4)D, and 5.1 mg/L and 17.0 mg/L for indirect UV, respectively. The linearity was obtained over the range from 2.5 to 400 mg/L for C(4)D and from 12.5 to 400 mg/L for indirect UV. The interday precisions were within 2.3-5.7% and intraday precisions were within 1.6-9.0% for C(4)D as well as 2.1-9.3%, 5.6-10.1% for indirect UV in spiked saliva, respectively. The recoveries were within 87.2-104.4%. The matrix effects were +53.2% for small concentrations up to 25 mg/L for C(4)D and +23.6% for concentrations up to 75 for mg/L for indirect UV detection. No matrix effects were observed for higher concentration levels. In conclusion, CE-C4D-indirect UV can offer a rapid, accurate, sensitive, and definitive method for the determination of GHB abuse in saliva samples as a forensic screening tool.

  4. 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

    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, {(10 × 10 cm² 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. RESULTS: 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. CONCLUSION: 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.

  5. Key comparison BIPM.RI(I)-K6 of the standards for absorbed dose to water at 10 g cm-2 of the NMIJ, Japan and the BIPM in accelerator photon beams

    Science.gov (United States)

    Picard, S.; Burns, D. T.; Roger, P.; Shimizu, M.; Morishita, Y.; Kato, M.; Tanaka, T.; Kurosawa, T.; Saito, N.

    2016-01-01

    A comparison of the dosimetry for accelerator photon beams was carried out between the National Metrology Institute of Japan (NMIJ) and the Bureau International des Poids et Mesures (BIPM) from 9 to 23 April 2015. The comparison was based on the determination of absorbed dose to water at 10 g cm-2 for three radiation qualities at the NMIJ. The results, reported as ratios of the NMIJ and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9966 (47) at 6 MV, 0.9965 (60) at 10 MV and 0.9953 (50) at 15 MV. This result is the eighth 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).

  6. Determination of transit dose profile for a {sup 192}Ir HDR source

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, G. P. [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP, Sao Paulo 05508-000, Brazil and Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Rubo, R. A.; Santos, G. R. dos [Hospital das Clinicas da Universidade de Sao Paulo - HC/FMUSP, Sao Paulo 05403-900 (Brazil); Minamisawa, R. A. [Laboratory for Micro- and Nanotechnology Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Antunes, P. C. G.; Yoriyaz, H. [Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP, Sao Paulo 05508-000 (Brazil)

    2013-05-15

    Purpose: Several studies have reported methodologies to calculate and correct the transit dose component of the moving radiation source for high dose rate (HDR) brachytherapy planning systems. However, most of these works employ the average source speed, which varies significantly with the measurement technique used, and does not represent a realistic speed profile, therefore, providing an inaccurate dose determination. In this work, the authors quantified the transit dose component of a HDR unit based on the measurement of the instantaneous source speed to produce more accurate dose values. Methods: The Nucletron microSelectron-HDR Ir-192 source was characterized considering the Task Group 43 (TG-43U1) specifications. The transit dose component was considered through the calculation of the dose distribution using a Monte Carlo particle transport code, MCNP5, for each source position and correcting it by the source speed. The instantaneous source speed measurements were performed in a previous work using two optical fibers connected to a photomultiplier and an oscilloscope. Calculated doses were validated by comparing relative dose profiles with those obtained experimentally using radiochromic films. Results: TG-43U1 source parameters were calculated to validate the Monte Carlo simulations. These agreed with the literature, with differences below 1% for the majority of the points. Calculated dose profiles without transit dose were also validated by comparison with ONCENTRA{sup Registered-Sign} Brachy v. 3.3 dose values, yielding differences within 1.5%. Dose profiles obtained with MCNP5 corrected using the instantaneous source speed profile showed differences near dwell positions of up to 800% in comparison to values corrected using the average source speed, but they are in good agreement with the experimental data, showing a maximum discrepancy of approximately 3% of the maximum dose. Near a dwell position the transit dose is about 22% of the dwell dose delivered

  7. Chewing-gum stimulation did not reduce the absorbed dose to salivary glands during radioiodine treatment of thyroid cancer as inferred from pre-therapy 124I PET/CT imaging

    OpenAIRE

    Jentzen, Walter; Richter, Marion; Nagarajah, James; Poeppel, Thorsten Dirk; Brandau, Wolfgang; Dawes, Colin; Bockisch, Andreas; Binse, Ina

    2014-01-01

    Background The goal of this prospective study was to estimate the absorbed (radiation) doses to salivary glands in radioiodine therapy of thyroid cancer under chewing-gum stimulation using 124I positron emission tomography (PET)/computed tomography (CT) imaging. Methods Duplex ultrasonography was conducted in three test persons for visual comparison of the glandular blood flow with three different stimulation types (no stimulation, chewing tasteless gum base, sucking on lemon slices). Ten pat...

  8. 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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    Apostoaei, Andrei Iulian

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

  10. 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.

  11. 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.

  12. Absorbed radiation by various tissues during simulated endodontic radiography

    International Nuclear Information System (INIS)

    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

  13. Determination and reliability of dose coefficients for radiopharmaceuticals; Ermittlung der Zuverlaessigkeit von Dosiskoeffizienten fuer Radiopharmaka

    Energy Technology Data Exchange (ETDEWEB)

    Spielmann, V.; Li, W.B.; Zankl, M.; Oeh, U.

    2015-11-15

    The dose coefficients used in nuclear medicine for dose calculations of radiopharmaceuticals are based on recommendations by ICRP (International Commission on radiological protection) and the MIRD (Medical Internal Radiation Dose Committee) using mathematical models for the temporal activity distributions in organs and tissues (biokinetic models) and mathematical models of the human body. These models using an idealized human body do not include uncertainty estimations. The research project is aimed to determine the uncertainties and thus the reliability of the dose coefficients for radiopharmaceuticals and to identify the biokinetic and dosimetric parameters that contribute most of the uncertainties.

  14. Determination of optical constants n and k of thin films from absorbance data using Kramers-Kronig relationship.

    Science.gov (United States)

    Rocha, W R M; Pilling, S

    2014-04-01

    We present a code, called NKABS, to determine optical constants (complex refractive index) of thin films directly from the absorbance data in the infrared. The code is written in the Python language, which is more accurate and faster than previous methods in the literature. For solving the Kramers-Kronig relationship, we used the Maclaurin's methodology. Unlike other codes, which found convergence in 30-40 iterations, the NKABS reach the convergence in just 4 or 5 iterations. Additionally, to evaluate the error, this code calculates the MAPE (Mean Absolute Percentage Error) and the chi-square χ(2). The typical MAPE error obtained using NKABS is less than 1×10(-3)%. To illustrate the functionality of this code, we calculate the optical constants in the infrared spectral region of 28 different samples of astrophysical interest at different temperatures (10-300K), which simulates molecules in space environments, mostly the ones called astrophysical ices. The samples were obtained from the condensation of pure gases (e.g. CO, CO2, NH3, SO2), from the sublimation in vacuum of pure liquids (e.g. water, acetone, acetonitrile, acetic acid, formic acid, ethanol and methanol) and from mixtures of different species (e.g. H2O:CO2, H2O:CO:NH3, H2O:CO2:NH3:CH4). Additionally films of solid biomolecules samples of astrochemistry/astrobiology interest (e.g. glycine, adenine) were probed. The code and the data-base obtained here are available on-line. The NKABS can also be employed to calculate refractive index of processed samples (by heating or radiation). Such data and the refractive index of virgin samples are required as input in several astrophysical models that calculate the radiative transfer in dusty astrophysical environments such as protoplanetary disks and circumstellar environments as well as dense molecular clouds.

  15. Determination of dose to patient in different teams of TC and assessment with international reference levels

    International Nuclear Information System (INIS)

    The increase in CT studies and the differences observed between the different equipment used in our hospital prompted us to determine the doses to patients in different studies and check the results obtained with the reference values published internationally. (Author)

  16. Determination of sterilization dose of cellulose microbial membrane by electron beam irradiation using ISO 11137

    International Nuclear Information System (INIS)

    The calculation of sterilization dose of cellulose microbial by electron beam irradiation has been done based on International Organization for Standardization (ISO) 11137. Cellulose microbial pellicle was prepared by static fermentation of A. xylinum in a medium containing coconut water as a micro nutrient source. The pellicle was then hand pressed at ambient temperature in order to get membrane with thickness of 0.03 ± 0.01 mm. Sterilization dose of electron beam was determined based on ISO 11137 through three steps: calculation of bioburden, determination of verification dose and sterilization dose based on Table 2. The results showed that the average bioburden of batch 1, 2 and 3 were 67.4; 92.6; 91 cfu, respectively and overall average bioburden was 83.7 cfu. The batch average bioburden was smaller than twice of overall average bioburden, so overall average of bioburden was used to determine the verification dose. Based on ISO 11137, the verification dose was at 7.8 kGy. The results of sterility test on 100 pieces of membranes after irradiated at verification dose, showed that only one membrane had positive bacteria growth. From these results, it can be concluded that sterilization dose of cellulose microbial membrane irradiated by electron beam with the SAL of 10-6 was 21 kGy. (author)

  17. Methodology for determining doses to in-field, out-of-field and partially in-field organs for late effects studies in photon radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Howell, Rebecca M; Scarboro, Sarah B; Kry, Stephen F; Newhauser, Wayne D [Graduate School of Biomedical Sciences, University of Texas Health Science Center, 6767 Bertner Avenue, Houston, TX 77030 (United States); Taddei, Phillip J [Department of Radiation Physics, Unit 94, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030 (United States); Krishnan, Sunil, E-mail: rhowell@mdanderson.or [Department of Radiation Oncology, Unit 97, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030 (United States)

    2010-12-07

    An important but little examined aspect of radiation dosimetry studies involving organs outside the treatment field is how to assess dose to organs that are partially within a treatment field; this question is particularly important for studies intended to measure total absorbed dose in order to predict the risk of radiogenic late effects, such as second cancers. The purpose of this investigation was therefore to establish a method to categorize organs as in-field, out-of-field or partially in-field that would be applicable to both conventional and modern radiotherapy techniques. In this study, we defined guidelines to categorize the organs based on isodose inclusion criteria, developed methods to assess doses to partially in-field organs, and then tested the methods by applying them to a case of intensity-modulated radiotherapy for hepatocellular carcinoma based on actual patient data. For partially in-field organs, we recommend performing a sensitivity test to determine whether potential inaccuracies in low-dose regions of the DVH (from the treatment planning system) have a substantial effect on the mean organ dose, i.e. >5%. In such cases, we suggest supplementing calculated DVH data with measured dosimetric data using a volume-weighting technique to determine the mean dose.

  18. Methodology for determining doses to in-field, out-of-field and partially in-field organs for late effects studies in photon radiotherapy

    Science.gov (United States)

    Howell, Rebecca M.; Scarboro, Sarah B.; Taddei, Phillip J.; Krishnan, Sunil; Kry, Stephen F.; Newhauser, Wayne D.

    2010-12-01

    An important but little examined aspect of radiation dosimetry studies involving organs outside the treatment field is how to assess dose to organs that are partially within a treatment field; this question is particularly important for studies intended to measure total absorbed dose in order to predict the risk of radiogenic late effects, such as second cancers. The purpose of this investigation was therefore to establish a method to categorize organs as in-field, out-of-field or partially in-field that would be applicable to both conventional and modern radiotherapy techniques. In this study, we defined guidelines to categorize the organs based on isodose inclusion criteria, developed methods to assess doses to partially in-field organs, and then tested the methods by applying them to a case of intensity-modulated radiotherapy for hepatocellular carcinoma based on actual patient data. For partially in-field organs, we recommend performing a sensitivity test to determine whether potential inaccuracies in low-dose regions of the DVH (from the treatment planning system) have a substantial effect on the mean organ dose, i.e. >5%. In such cases, we suggest supplementing calculated DVH data with measured dosimetric data using a volume-weighting technique to determine the mean dose.

  19. Determination of the equivalent of environmental dose, H*(d), in a radiotherapy installation; Determinacao do equivalente de dose ambiental, H*(d), em uma instalacao de radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Lima, M.A.F.; Borges, J.C. [Universidade Federal de Rio de Janeiro, PEN/COPPE/UFRJ Caixa Postal 68509 21945-970, Rio de Janeiro (Brazil); Mota, H.C. [Instituto de Radio Protecao e Dosimetria, IRD/CNEN Caixa Postal 37750 22780-160, Rio de Janeiro (Brazil)

    1998-12-31

    In order to put into practice radiological protection has been required conversion factors for environmental dose equivalent determination to air kerma value for different kinds of photon and electron beams, such dose values have been determined in a spheric phantom of 30 cm diameter in a alignment field and expanded in a depth of this sphere. Details will be given for determining of equivalent dose distribution calculation using Monte Carlo computational method (ESG4) following the recommendations of ICRU. (Author)

  20. 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

  1. 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)

  2. 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)

  3. Patient-specific CT dose determination from CT images using Monte Carlo simulations

    Science.gov (United States)

    Liang, Qing

    Radiation dose from computed tomography (CT) has become a public concern with the increasing application of CT as a diagnostic modality, which has generated a demand for patient-specific CT dose determinations. This thesis work aims to provide a clinically applicable Monte-Carlo-based CT dose calculation tool based on patient CT images. The source spectrum was simulated based on half-value layer measurements. Analytical calculations along with the measured flux distribution were used to estimate the bowtie-filter geometry. Relative source output at different points in a cylindrical phantom was measured and compared with Monte Carlo simulations to verify the determined spectrum and bowtie-filter geometry. Sensitivity tests were designed with four spectra with the same kVp and different half-value layers, and showed that the relative output at different locations in a phantom is sensitive to different beam qualities. An mAs-to-dose conversion factor was determined with in-air measurements using an Exradin A1SL ionization chamber. Longitudinal dose profiles were measured with thermoluminescent dosimeters (TLDs) and compared with the Monte-Carlo-simulated dose profiles to verify the mAs-to-dose conversion factor. Using only the CT images to perform Monte Carlo simulations would cause dose underestimation due to the lack of a scatter region. This scenario was demonstrated with a cylindrical phantom study. Four different image extrapolation methods from the existing CT images and the Scout images were proposed. The results show that performing image extrapolation beyond the scan region improves the dose calculation accuracy under both step-shoot scan mode and helical scan mode. Two clinical studies were designed and comparisons were performed between the current CT dose metrics and the Monte-Carlo-based organ dose determination techniques proposed in this work. The results showed that the current CT dosimetry failed to show dose differences between patients with the same

  4. 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.

  5. 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.

  6. Determination of uranium content in dental porcelains by means of the fission track method and estimation of radiation dose to oral mucosa by radioactive elements

    International Nuclear Information System (INIS)

    Porcelain teeth, some of which contain uranium compounds for aesthetic purpose, have been widely used in dental clinics. Hazardous effects due to uranium radiation have been suggested in recent publications. In the present study uranium concentrations were determined in four major brands of porcelain teeth marketed in Japan using the fission track method, and the absorbed doses to oral tissued were calculated. Average uranium concentrations of the brands studied were determined to be 3.6 ppm (0.33-10 ppm, Japan), 18 ppm (0.69-81 ppm, Japan), 9.4 ppm (2.5-14 ppm, Japan) and 82 ppm (11-205 ppm, U.S.), respectively. The corresponding dose equivalents at the surface of oral mucosal membrane were 2.9 rem yr-1. 14 rem yr-1, 7.6 rem yr-1 and 66 rem yr-1. (author)

  7. Determination of uranium content in dental porcelains by means of the fission track method and estimation of radiation dose to oral mucosa by radioactive elements

    International Nuclear Information System (INIS)

    Porcelain teeth, some of which contained uranium compounds for aesthetic purpose, have been widely used in dental clinics. Recently, the hazardous effects by uranium radiation were suggested. In the present study, the authors carried out the determination of uranium concentrations of four major brands of porcelain teeth marketed in Japan using the fission track method, and the absorbed doses of oral tissues were calculated by the authors' introduced formula for calculation of alpha radiation. Average uranium concentrations of the brands studied were determined 3.6 ppm (0.33 - 10 ppm, Japan), 18 ppm (0.69 - 81 ppm, Japan), 9.4 ppm (2.5 - 14 ppm, Japan) and 82 ppm (11 - 205 ppm, U.S.A.), respectively. The corresponding dose equivalents at the surface of oral mucosal membrane were 2.9 rem y-1, 14 rem y-1, 7.6 rem y-1 and 66 rem y-1. (author)

  8. Traceability of metrological references in absorbed doses from the water of the Dosimetry Postal Program (PPD) of Laboratorio de Ciencias Radiologicas from Universidade do Estado do Rio de Janeiro, LCR/UERJ

    International Nuclear Information System (INIS)

    An experimental group of Quality Assurance for external radiotherapy was formed in Laboratorio de Ciencias Radiologicas/UERJ in agreement with the Institut Gustave-Roussy, European Society for Therapeutic Radiology and Oncology and the International Atomic Energy Agency. This group has as main objective to promote a high and homogeneous standard in the accuracy of the delivered dose, for the hospitals and clinics, to a patient's treatment volume. One of the ways of assurance this accuracy, in a wide country and with smaller costs, is the Postal Evaluation of Doses. This work presents the traceability of metrological references in absorbed dose to water of the Dosimetry Postal Program of LCR/UERJ. (author)

  9. 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)

  10. Determination of gelation dose of poly(vinyl acetate) by a spectrophotometric method

    Energy Technology Data Exchange (ETDEWEB)

    Guven, Olgun; Yigit, Fatma

    1986-01-01

    The gelation point is an important property of polymers undergoing crosslinking when subjected to high energy radiation. This point is generally determined by viscometric and solubility methods or by mechanical measurements. When crosslinking and discoloration take place simultaneously, gelation doses can be determined spectrophotometrically. In this work it is demonstrated that the gelation dose of poly (vinyl acetate) can be determined by simply recording the u.v.-vis. spectra of the solutions of ..gamma..-irradiated polymer. The reliability of the method is verified by viscometric and solubility measurements.

  11. Dose determination in computed tomography; Determinacion de dosis en tomografia computada

    Energy Technology Data Exchange (ETDEWEB)

    Descamps, C.; Garrigo, E.; Venencia, D. [Fundacion Marie Curie, Instituto Privado de Radioterapia, Departamento de Fisica Medica, Obispo Oro 423, X5000BFI Cordoba (Argentina); Gonzalez, M. [Universidad Nacional de Cordoba, Facultad de Ciencias Exactas, Fisicas y Naturales, Av. Velez Sarsfield 299, Corboba (Argentina); Germanier, A., E-mail: agermani@ceprocor.uncor.edu [Ministerio de Ciencia y Tecnologia, Ceprocor, Alvarez de Arenas 230, X5004AAP Barrio Juniors, Cordoba (Argentina)

    2011-10-15

    In the last years the methodologies to determine the dose in computed tomography have been revised. In this work was realized a dosimetric study about the exploration protocols used for simulation of radiotherapy treatments. The methodology described in the Report No. 111 of the American Association of Medical Physiques on a computed tomograph of two cuts was applied. A cylindrical phantom of water was used with dimensions: 30 cm of diameter and 50 cm of longitude that simulates the absorption and dispersion conditions of a mature body of size average. The doses were determined with ionization chamber and thermoluminescent dosimetry. The results indicate that the dose information that provides the tomograph underestimates the dose between 32 and 35%.

  12. Determination of the dose around an ovoid for treatments in intracavitary brachytherapy Hdr

    International Nuclear Information System (INIS)

    On this work the results of the dosimetric measurements are presented around an ovoid of 2 cm diameter. The measurements were carried out using a water mannequin, an ovoid, a radiation gamma source of 192Ir and thermoluminescent dosemeters. The dosimetry was realized in the direction of the rectum and bladder. To know the effect of the shielding of the devices type Manchester in the dose, the thermoluminescent dosemeters were irradiated to a radiation gamma source of 192Ir contained in the Gamma med Plus equipment. The planning was realized normalizing the calculation to 2.5 cm from the applicator center on the transverse plane (2.5, 0, 0). The results show that the dose distribution for an ovoid without shielding is more uniform in the transversal plane to the source axis. The results were compared with the calculated results by means of the planning system BrachyVision. While the absorbed dose distribution around an ovoid with shielding is completely anisotropic. This anisotropic is due to the shielding. (Author)

  13. Impact of photon cross section systematic uncertainties on Monte Carlo-determined depth-dose distributions

    CERN Document Server

    Aguirre, Eder; David, Mariano; deAlmeida, Carlos E

    2016-01-01

    This work studies the impact of systematic uncertainties associated to interaction cross sections on depth dose curves determined by Monte Carlo simulations. The corresponding sensitivity factors are quantified by changing cross sections in a given amount and determining the variation in the dose. The influence of total cross sections for all particles, photons and only for Compton scattering is addressed. The PENELOPE code was used in all simulations. It was found that photon cross section sensitivity factors depend on depth. In addition, they are positive and negative for depths below and above an equilibrium depth, respectively. At this depth, sensitivity factors are null. The equilibrium depths found in this work agree very well with the mean free path of the corresponding incident photon energy. Using the sensitivity factors reported here, it is possible to estimate the impact of photon cross section uncertainties on the uncertainty of Monte Carlo-determined depth dose curves.

  14. International programme on the health effects of the Chernobyl accident (IPHECA). 'Epidemiological registry' Pilot project. Reconstruction of absorbed doses from external exposure of the population living in areas of Russia contaminated as a result of the accident at the Chernobyl nuclear power plant

    International Nuclear Information System (INIS)

    In order to carry out epidemiological research on the influence of radiation factors on the health of people living in centres of population areas contaminated as a result of the Chernobyl accident, a knowledge of the amount of external and internal exposure to the thyroid gland and the whole body is crucial. After seven years of the Chernobyl accident, an attempt was made to reconstruct the complete dynamic picture of radioactive contamination of Russian territory, taking into consideration current data on the temporal behavior of the source of accidental radionuclide emissions from the reactor where the accident occurred, meteorological conditions at the time, detailed measurements of cesium 137 fall-out density on CIS territory, air exposure dose rate measurements. Such an approach will enable to determine absorbed doses in centers of population, where radiation parameters were not measured at all. 17 refs, 6 figs, 6 tabs, 1 map

  15. Determination of conversion factors of kerma and fluence to ambient dose equivalent for X-rays generated between 50 kVp to 125 kVp

    International Nuclear Information System (INIS)

    The ambient dose equivalent was determined experimentally on the interval of energy of X ray applied in diagnostic radiology. A PMMA sphere was used to simulate the trunk human (phantom), based on the definition of the report ICRU 39. The absorbed dose in different positions in the phantom was determined using LiF-TLD 100. The X ray spectra were measured with a high-purity germanium detector (HP Ge). It was also determined the HVL and the effective energy in this energy range. The conversion coefficient of the Kair and Φ to H*(d) were determined to 10, 50 and 60 mm deep in the PMMA sphere. The obtained values were compared with data of the literature. The maximum uncertainty obtained for the coefficients was 7.2%. All parameters were also determined to the X ray quality of the incident and transmitted beam by the patient, according to the recommendation of the standard DIN 6872. The conversion factor was calculated for those situations where the X-ray beam is transmitted by a layer and Pb and it is necessary to estimate the effective dose, as in the case of shielding project of radiology diagnosis room. (author)

  16. Determination of fluence-to-dose conversion coefficients by means of artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Soto B, T. G.; Rivera P, E.; De Leon M, H. 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); Gallego, E.; Lorente, A., E-mail: tzinnia.soto@gmail.com [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, Jose Gutierrez Abascal No. 2, 28006 Madrid (Spain)

    2012-10-15

    In this paper is presented an Artificial Neural Network (Ann) that has been designed, trained and validated to determinate the effective dose e, ambient dose equivalent h(10) and personal dose equivalent hp(10,{theta}) fluence-to-dose conversion coefficients at different positions, having as only input data 7 count rates obtained with a Bonner Sphere Spectrometer (Bss) system. A set of 211 neutron spectra and the fluence-to-dose conversion coefficients published by the International Atomic Energy Agency were used to train and validate the Ann. This set was divided into 2 subsets, one of 181 elements to train the Ann and the remaining 30 to validate it. The Ann was trained using Bss count rates as input data and the fluence-to-dose conversion coefficients as output data. The network was validated and tested with the set of 30 elements that were not used during the training process. Good results were obtained proving that Ann are a good choice for calculating the fluence-to-dose conversion coefficients having as only data the count rates obtained with a Bss. (Author)

  17. Neutron Dose Determination in Criticality Accidents by Gamma Counting of the Patient's Dental Fillings

    International Nuclear Information System (INIS)

    Since most people have some teeth filled with the normal mercury-silver (Hg 50%, Ag 30%) alloy, an attempt has been made to determine the neutron dose received in a criticality accident by counting the activity of the amalgam due to (n, γ) reactions. Thermal neutron doses less than about 10 rads can be estimated by measuring the induced activity in mercury or copper (which is present in trace quantities in the amalgam) and doses less than about 20 rads can be estimated by measuring the induced activity in silver. The method gives an approximate result half a day after the accident and a more accurate result can be obtained after a few days. The method, in combination with the film dosimeter and other standard methods, may help to give a more complete idea of the dose received by a person in a criticality accident. (author)

  18. Determination the lethal dose of ascaris lumbricoides ova by gamma irradiation

    CERN Document Server

    Shamma, M A; Sharabi, N

    2002-01-01

    The lethal gamma irradiation dose of ascaris lumbricoides which collected from Damascus Sewage water Plant was determined. Ascaris lumbricoides ova were treated with several gamma irradiation doses with (0.1, 0.2, 0.3, 0.4,...and 1.5 KGy). No morphological changes were observed on the eggs when directly examined microscopically after irradiation. However after two weeks of incubation at 37 degree centigrade the cell contents of the eggs which irradiated with 0.5 KGy and beyond were fragmented and scattered in the whole eggs and no larvae were observed after eight weeks of incubation. It is concluded that the dose 0.5 my be considered as the dose of choice if sewage water is to be treated by gamma rays.

  19. Determination of surface dose rate from a 90Sr ophthalmic applicator

    International Nuclear Information System (INIS)

    Surface dose rates from two 90Sr ophthalmic applicators were measured using thin thermoluminescent dosimeter (TLD) chips. The TLD's were calibrated against the 90Sr source itself. The calibration technique is described. The results were compared to those obtained by three other techniques. The calibration in terms of roentgen equivalent betas per second provided by the manufacturer was found to be ∼30% lower when compared to our measured dose rates. The surface dose rates obtained with the TLD's calibrated against 6-MV x rays were 18% higher. One of the two sources was sent to both the National Institute of Standards and Technology (NIST) and Amersham International for calibration. NIST and Amersham use extrapolation chambers as a Bragg--Gray cavity to determine the surface dose rate. NIST results gave values higher than ours by ∼5%. The Amersham results were ∼35% lower than ours

  20. 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)

  1. Determination of gamma radiation dose for destruction of Salmonella spp. in chicken flesh

    International Nuclear Information System (INIS)

    The aim of this study was to determinate: 1) the radio sensibility of Salmonella typhimurium ATCC 14028 in soy trypticase broth; 2) the radio sensibility of Salmonella typhimurium ATCC 14028 in chicken thigh and; 3) to recommend a radiation dose which can be non hazardous for human consumption

  2. Pharmacological dose of alpha-tocopherol induces cardiotoxicity in Wistar rats determined by echocardiography and histology

    Science.gov (United States)

    The effect of pharmacological dose of alpha-tocopherol on heart health was determined in Wistar rats. Animals were randomly assigned to either C (control, n = 11) or E (alpha-tocopherol, n = 11) group. Animals received corn oil (C) or alpha-tocopherol dissolved in corn oil (250 mg alpha-tocopherol/[...

  3. Determination of Archaeological Doses for TL Dating Using and Automated TL Apparatus

    DEFF Research Database (Denmark)

    Bøtter-Jensen, Lars; Mejdahl, V.

    1980-01-01

    An automated reader was designed with special regard to TL dating. The reader is a microprocessor-controlled sample changer system that can construct the primary and secondaty response curves required for determination of the archaeological dose of quartz and feldspar extracted from pottery...

  4. Dose determination in interventional procedures at a hospital, using Al2O3:C detectors

    International Nuclear Information System (INIS)

    Full text: Interventional practices have increased in most countries over the past 20 years, combining diagnostic and therapeutic procedures. However, the determination of staff doses in fluoroscopy is difficult, because the examinations are dynamic in nature. Such procedures are complex and they involve prolonged irradiations, providing high radiation doses to patients and to the staff. The effective dose of the staff can be estimated by direct methods, using the optically stimulated luminescence (OSL) technique. In the present work inLight dosimeters and an inLight microstar reader, Landauer, were utilized. These dosimeters are formed by four aluminium oxide (Al2O3:C) detectors and there are aluminium, copper and plastic filters and an open window in each badge. In this work, the dosimeters were utilized for the dose determinations in interventional procedures. Initially the calibration factors and the energy dependence of Al2O3:C dosimeters were obtained in the range of 60 to 120 kV. The doses were evaluated at different positions on the staff during the routine procedures at the Hospital Sao Paulo. The results will be compared with those previously obtained using thermoluminescent CaSO4:Dy

  5. Committed effective dose determination in cereal flours by gamma-ray spectrometry

    International Nuclear Information System (INIS)

    The health impact from radionuclides ingestion of foodstuffs was evaluated by the committed effective doses determined in commercial samples of South-Brazilian cereal flours (soy, wheat, corn, manioc, rye, oat, barley and rice flour). The radioactivity traces of 228Th, 228Ra, 226Ra, 40K, 7Be and 137Cs were measured by gamma-ray spectrometry employing a 66% relative efficiency HPGe detector. The energy resolution for the 1332.46 keV line of 60Co was 2.03 keV. The committed effective doses were calculated with the activities analyzed in the present flour samples, the foodstuff rates of consumption (Brazilian Institute of Geography and Statistics) and the ingestion dose coefficients (International Commission of Radiological Protection). The reliability median activities were verified with χ2 tests, assuring the fittings quality. The highest concentration levels of 228Th and 40K were 3.5 ± 0.4 and 1469 ± 17 Bq.kg-1 for soy flour, respectively, with 95% of confidence level. The lower limit of detection for 137Cs ranged from 0.04 to 0.4 Bq.kg-1. The highest committed effective dose was 0.36 μSv.y-1 for 228Ra in manioc flour (adults). All committed effective doses determined at the present work were lower than the UNSCEAR limits of 140 μSv.y-1 and much lower than the ICRP (1991) limits of 1 mSv.y-1, for general public. There are few literature references for natural and artificial radionuclides in foodstuffs and mainly for committed effective doses. This work brings the barley flour data, which is not present at the literature and 7Be data which is not encountered in foodstuffs at the literature, besides all the other flours data information about activities and committed effective doses. (author)

  6. In-situ determination of the effective absorbance of thin μc-Si:H layers growing on rough ZnO:Al

    Directory of Open Access Journals (Sweden)

    Meier Matthias

    2013-10-01

    Full Text Available In this study optical transmission measurements were performed in-situ during the growth of microcrystalline silicon (μc-Si:H layers by plasma enhanced chemical vapor deposition (PECVD. The stable plasma emission was used as light source. The effective absorption coefficient of the thin μc-Si:H layers which were deposited on rough transparent conductive oxide (TCO surfaces was calculated from the transient transmission signal. It was observed that by increasing the surface roughness of the TCO, the effective absorption coefficient increases which can be correlated to the increased light scattering effect and thus the enhanced light paths inside the silicon. A correlation between the in-situ determined effective absorbance of the μc-Si:H absorber layer and the short-circuit current density of μc-Si:H thin-film silicon solar cells was found. Hence, an attractive technique is demonstrated to study, on the one hand, the absorbance and the light trapping in thin films depending on the roughness of the substrate and, on the other hand, to estimate the short-circuit current density of thin-film solar cells in-situ, which makes the method interesting as a process control tool.

  7. SU-E-T-91: Correction Method to Determine Surface Dose for OSL Detectors

    International Nuclear Information System (INIS)

    Purpose: OSL detectors are commonly used in clinic due to their numerous advantages, such as linear response, negligible energy, angle and temperature dependence in clinical range, for verification of the doses beyond the dmax. Although, due to the bulky shielding envelope, this type of detectors fails to measure skin dose, which is an important assessment of patient ability to finish the treatment on time and possibility of acute side effects. This study aims to optimize the methodology of determination of skin dose for conventional accelerators and a flattening filter free Tomotherapy. Methods: Measurements were done for x-ray beams: 6 MV (Varian Clinac 2300, 10×10 cm2 open field, SSD = 100 cm) and for 5.5 MV (Tomotherapy, 15×40 cm2 field, SAD = 85 cm). The detectors were placed at the surface of the solid water phantom and at the reference depth (dref=1.7cm (Varian 2300), dref =1.0 cm (Tomotherapy)). The measurements for OSLs were related to the externally exposed OSLs measurements, and further were corrected to surface dose using an extrapolation method indexed to the baseline Attix ion chamber measurements. A consistent use of the extrapolation method involved: 1) irradiation of three OSLs stacked on top of each other on the surface of the phantom; 2) measurement of the relative dose value for each layer; and, 3) extrapolation of these values to zero thickness. Results: OSL measurements showed an overestimation of surface doses by the factor 2.31 for Varian 2300 and 2.65 for Tomotherapy. The relationships: SD2300 = 0.68 × M2300-12.7 and SDτoμo = 0.73 × Mτoμo-13.1 were found to correct the single OSL measurements to surface doses in agreement with Attix measurements to within 0.1% for both machines. Conclusion: This work provides simple empirical relationships for surface dose measurements using single OSL detectors

  8. 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.

  9. 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)

  10. Determination of Effect of Low Dose Vs Moderate Dose of Clofibrate on the Decreasing in Serum Bilirubin Level in the Term Healthy Neonate

    OpenAIRE

    Mohammad Ashkan Moslehi; Narges Pishva

    2007-01-01

    Objective: This study was performed to determine the effect of low doses (25 mg/Kg) vs. moderate doses (50 mg/Kg) of clofibrate in treatment of non-hemolytic hyperbilirubin¬emia in healthy term neonates. Material & Methods: A clinical randomized controlled trial was performed in three groups of healthy term neonates. One group was treated with a single low dose of clofibrate (25 mg/Kg) while another group received a single moderate dose (50mg/kg) both orally plus phototherapy; the results wer...

  11. Determination of the conversion coefficient for ambient dose equivalent, H(10), from air kerma measurements; Determinacion del coeficiente de conversion para la dosis equivalente ambiental, H*(10), a partir de mediciones de kerma en aire

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez J, F. [UNAM, Facultad de Ciencias, Circuito Exterior, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Alvarez R, J. T., E-mail: trinidad.alvarez@inin.gob.mx [ININ, Departamento de Metrologia de Radiaciones Ionizantes, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    Namely the operational magnitudes can be determined by the product of a conversion coefficient by exposure air kerma or fluence, etc. In particular in Mexico for the first time is determined the conversion coefficient (Cc) for operational magnitude Environmental Dose Equivalent H(10) by thermoluminescence dosimetry (TLD) technique. First 30 TLD-100 dosimeters are calibrated in terms of air kerma, then these dosimeters are irradiated inside a sphere ICRU type of PMMA and with the aid of theory cavity the absorbed dose in PMMA is determined at a depth of 10 mm within the sphere D{sub PMMA}(10), subsequently absorbed dose to ICRU tissue is corrected and the dose equivalent H(10) is determined. The Cc is determined as the ratio of H(10)/K{sub a} obtaining a value of 1.20 Sv Gy{sup -1} with a u{sub c}= 3.66%, this being consistent with the published value in ISO-4037-3 of 1.20 Sv Gy{sup -1} with a u{sub c}= 2%. (Author)

  12. Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter

    DEFF Research Database (Denmark)

    Borg, J.; Christensen, P.

    1995-01-01

    The extrapolation chamber measurement method is the basic method for the determination of dose rates in beta radiation fields and the method has been used for the establishment of beta calibration fields. The paper describes important details of the method and presents results from the measurement...... of depth-dose profiles from different beta radiation fields with E(max) values down to 156 keV. Results are also presented from studies of GM counters for use as survey instruments for monitoring beta dose rates at the workplace. Advantages of GM counters are a simple measurement technique and high...... sensitivity. GM responses were measured from exposures in different beta radiation fields using different filters in front of the GM detector and the paper discusses the possibility of using the results from GM measurements with two different filters in an unknown beta radiation field to obtain a value of the...

  13. Determination of the delivered hemodialysis dose using standard methods and on-line clearance monitoring

    Directory of Open Access Journals (Sweden)

    Vlatković Vlastimir

    2006-01-01

    Full Text Available Background/aim: Delivered dialysis dose has a cumulative effect and significant influence upon the adequacy of dialysis, quality of life and development of co-morbidity at patients on dialysis. Thus, a great attention is given to the optimization of dialysis treatment. On-line Clearance Monitoring (OCM allows a precise and continuous measurement of the delivered dialysis dose. Kt/V index (K = dialyzer clearance of urea; t = dialysis time; V = patient's total body water, measured in real time is used as a unit for expressing the dialysis dose. The aim of this research was to perform a comparative assessment of the delivered dialysis dose by the application of the standard measurement methods and a module for continuous clearance monitoring. Methods. The study encompassed 105 patients who had been on the chronic hemodialysis program for more than three months, three times a week. By random choice, one treatment per each controlled patient was taken. All the treatments understood bicarbonate dialysis. The delivered dialysis dose was determined by the calculation of mathematical models: Urea Reduction Ratio (URR singlepool index Kt/V (spKt/V and by the application of OCM. Results. Urea Reduction Ratio was the most sensitive parameter for the assessment and, at the same time, it was in the strongest correlation with the other two, spKt/V indexes and OCM. The values pointed out an adequate dialysis dose. The URR values were significantly higher in women than in men, p < 0.05. The other applied model for the delivered dialysis dose measurement was Kt/V index. The obtained values showed that the dialysis dose was adequate, and that, according to this parameter, the women had significantly better dialysis, then the men p < 0.05. According to the OCM, the average value was slightly lower than the adequate one. The women had a satisfactory dialysis according to this index as well, while the delivered dialysis dose was insufficient in men. The difference

  14. Real time determination of dose radiation through artificial intelligence and virtual reality

    International Nuclear Information System (INIS)

    In the last years, a virtual environment of Argonauta research reactor, sited in the Instituto de Engenharia Nuclear (Brazil), has been developed. Such environment, called here Argonauta Virtual (AV), is a 3D model of the reactor hall, in which virtual people (avatar) can navigate. In AV, simulations of nuclear sources and doses are possible. In a recent work, a real time monitoring system (RTMS) was developed to provide (by means of Ethernet TCP/IP) the information of area detectors situated in the reactor hall. Extending the scope of AV, this work is intended to provide a continuous determination of gamma radiation dose in the reactor hall, based in several monitored parameters. To accomplish that a module based in artificial neural network (ANN) was developed. The ANN module is able to predict gamma radiation doses using as inputs: the avatar position (from virtual environment), the reactor power (from RTMS) and information of fixed area detectors (from RTMS). The ANN training data has been obtained by measurements of gamma radiation doses in a mesh of points, with previously defined positions, for different power levels. Through the use of ANN it is possible to estimate, in real time, the dose received by a person at any position in Argonauta reactor hall. Such approach allows tasks simulations and training of people inside the AV system, without exposing them to radiation effects. (author)

  15. Radiation dose determines the method for quantification of DNA double strand breaks

    Energy Technology Data Exchange (ETDEWEB)

    Bulat, Tanja; Keta, Olitija; Korićanac, Lela; Žakula, Jelena; Petrović, Ivan; Ristić-Fira, Aleksandra [University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade (Serbia); Todorović, Danijela, E-mail: dtodorovic@medf.kg.ac.rs [University of Kragujevac, Faculty of Medical Sciences, Kragujevac (Serbia)

    2016-03-15

    Ionizing radiation induces DNA double strand breaks (DSBs) that trigger phosphorylation of the histone protein H2AX (γH2AX). Immunofluorescent staining visualizes formation of γH2AX foci, allowing their quantification. This method, as opposed to Western blot assay and Flow cytometry, provides more accurate analysis, by showing exact position and intensity of fluorescent signal in each single cell. In practice there are problems in quantification of γH2AX. This paper is based on two issues: the determination of which technique should be applied concerning the radiation dose, and how to analyze fluorescent microscopy images obtained by different microscopes. HTB140 melanoma cells were exposed to γ-rays, in the dose range from 1 to 16 Gy. Radiation effects on the DNA level were analyzed at different time intervals after irradiation by Western blot analysis and immunofluorescence microscopy. Immunochemically stained cells were visualized with two types of microscopes: AxioVision (Zeiss, Germany) microscope, comprising an ApoTome software, and AxioImagerA1 microscope (Zeiss, Germany). Obtained results show that the level of γH2AX is time and dose dependent. Immunofluorescence microscopy provided better detection of DSBs for lower irradiation doses, while Western blot analysis was more reliable for higher irradiation doses. AxioVision microscope containing ApoTome software was more suitable for the detection of γH2AX foci. (author)

  16. Real time determination of dose radiation through artificial intelligence and virtual reality

    International Nuclear Information System (INIS)

    In the last years, a virtual environment of Argonauta research reactor, sited in the Instituto de Engenharia Nuclear (Brazil), has been developed. Such environment, called here Argonauta Virtual (AV), is a 3D model of the reactor hall, in which virtual people (avatar) can navigate. In AV, simulations of nuclear sources and doses are possible. In a recent work, a real time monitoring system (RTMS) was developed to provide (by means of Ethernet TCP/I P) the information of area detectors situated in the reactor hall. Extending the scope of AV, this work is intended to provide a continuous determination of gamma radiation dose in the reactor hall, based in several monitored parameters. To accomplish that a module based in artificial neural network (ANN) was developed. The ANN module is able to predict gamma radiation doses using as inputs: the avatar position (from virtual environment), the reactor power (from RTMS) and information of fixed area detectors (from RTMS). The ANN training data has been obtained by measurements of gamma radiation doses in a mesh of points, with previously defined positions, for different power levels. Through the use of ANN it is possible to estimate, in real time, the dose received by a person at any position in Argonauta reactor hall. Such approach allows tasks simulations and training of people inside the AV system, without exposing them to radiation effects. (author)

  17. Evaluation of Absorbed Dose of Critical Organ in Rando Phantom under Head, Abdomen and Pelvis Spiral CT Scan by Thermo Luminescent Dosimetery - TLD

    OpenAIRE

    Gholamhosein Haddadi; Simin Mehdizadeh; Mohammad Bagher Haddadi; Mohammad Hasan Meshkibaf

    2011-01-01

    Background & Objectives: Computed tomography (CT) represents 11% of all diagnostic radiology procedures but it contributes to almost 67% of the total effective dose to the human population. In head and neck CT which consist of 1/3 of total CT scans, other critical organs such as lenses and thyroid are in the radiation field. Also in the abdomen and pelvis scan, irradiation of ovaries is unavoidable. Because of high sensitivity of these organs, the probability of abnormality and cancer in thes...

  18. 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)

  19. Determination of lethal doses of volatile and fixed oils of several plants